Dissertations / Theses on the topic 'Particulate organic carbon'
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1
Kommedal, Roald. "Degradation of polymeric and particulate organic carbon in biofilms." Doctoral thesis, Norwegian University of Science and Technology, Faculty of Natural Sciences and Technology, 2003. http://urn.kb.se/resolve?urn=urn:nbn:no:ntnu:diva-3.
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Polymeric and particulate organic carbon (POM) are fundamental compounds in the global cycling of carbon, and constitute significant amounts of BOD in municipal wastewater.
The main objective of this work is to study molecular size effects on degradation dynamics in biofilm systems. Specifically, the effect of substrate molecular weight on degradation kinetics and transport dynamics, location of depolymerisation enzyme activity and depolymerisation intermediate formation dynamics are assessed. A mathematical model for biofilm degradation dynamics is presented, and used for data interpretation and simulations.
Dextran, an -1,6 Glucan, was used as model substrate during batch degradation in a Rototorque biofilm reactor, in addition to batch tests on biofilm sub samples retrieved from the Rototorque, and during pure endo- and exo-Dextranase studies. Oxygen utilisation rate (OUR) estimates and bulk phase TOC mass balances were used to evaluate the effect of variable initial molecular weight on the observed half order removal coefficient (Harremoës, 1978; Rittmann and McCarty, 1980). Size exclusion-HPLC analysis for determination of bulk phase depolymerisation intermediates, and specific enzyme assays were used to evaluate transport dynamics of polymers and location of enzyme activity in the enhanced mixed population biofilm system.
Dextran removal rate decrease with increasing Dextran molecular weight. The observed areal half order removal rate coefficient, k1/2,A, demonstrate an approximate 10-fold decrease in the 1-500 kDa range, showing negative logarithmic correlation to the initial MW of Dextran. A less distinct correlation is observed above this transition limit (1-10 MDa). Evaluation of the Thiele moduli, from one step depolymerisation modelling, suggests that the logarithmic reduction in observed removal rate is caused by combined reaction rate and transport limitations. Transport limitations dominates as the polymeric substrate size increase and hinders biofilm matrix diffusion, and the removal rate becomes a surface limited process. Removal of Dextran is biomass dependent in what appears to be a non-linear dependency on biofilm thickness. Expressed as biomass areal density (g/m2), no depolymerisation is observed for thin biofilms (0.7 g/m2), slow for medium (3.7 g/m2) and high for thicker biofilms (5.2 g/m2).
Depolymerisation intermediates accumulated in the bulk phase over the entire Dextran size range during pure Dexranase studies, with even size distributions. Final products were oligo-isomaltoses (DP 2-6). Dextran was not depolymerised by -Glucosidase nor Oligo-1,6 Glucosidase. During biofilm reactor and slide sub-sample tests, low MW Dextran intermediates (1-10 kDa) accumulated in the bulk during depolymerisation of 160 kDa Dextran at 250 and 200 mg/l initial concentrations, but were not detected during experiments with 100 mg/l initial concentrations. Intermediate range Dextran (10-100 kDa) did not accumulate in either case. At the same conditions, some assimilable range Dextran (0.2-0.9 kDa) accumulated in the bulk liquid during initial 250 and 200 mg/l batches, but was not detected during 100 mg/l initial Dextran concentrations. The extent of bulk phase accumulation seems to depend on the biofilm growth rate, where more bulk phase accumulation is observed during experiments with starved compared to more actively growing biofilms. More intermediates accumulate during low MW initial standards, compared to higher. These observations indicate that the extent of bulk phase intermediate accumulation is balanced by the rate of depolymerisation, and the substrate uptake rate (growth). Accumulation of intermediate hydrolysis products in biofilm systems is therefore dependent on the slowly biodegradable organic (SBCOD) loading rate.
Dextranase was detected in the cellular fraction of the biofilms. The enzyme activity was not detected in any other biofilm sub compartments, implying that the exogenous enzyme remains attached to the cells while working on polymers. These findings support the conceptual model of Confer and Logan (1998), implying that bulk phase intermediate accumulation observed in this study and by others, is not a result of enzymatic activity in the bulk phase, but transport of intermediates from the biofilm matrix.
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Sparkes, Robert Bryon. "Marine sequestration of particulate organic carbon from mountain belts." Thesis, University of Cambridge, 2013. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.607829.
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Smith, Joanne Caroline. "Particulate organic carbon mobilisation and export from temperate forested uplands." Thesis, University of Cambridge, 2013. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.648250.
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Jorge, Danilo Custódio. "Particulate carbon in the atmosphere: distribution aging and wet deposition." Doctoral thesis, Universidade de Aveiro, 2016. http://hdl.handle.net/10773/16829.
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Doutoramento em Ciências e Engenharia do AmbienteDuring the last decades a significant number of studies was performed about the cycling of carbonaceous matter in the atmosphere. Despite the efforts of the scientific community, a full understanding about the composition and formation of carbonaceous aerosol in ambient air was not yet achieved, reflecting the great variety of emitting sources and the complexity of transformation processes in the atmosphere. In addition, very little is known about a specific type of carbonaceous aerosol: the indoor carbonaceous aerosol. Removal of particulate carbonaceous matter from the atmosphere is another component of the carbon cycle that has received poor attention from researchers. The main aim of this work was to contribute to a better understanding of the sources, transformation processes and removal of atmospheric carbonaceous matter. Particulate matter, organic carbon (OC) and elemental carbon (EC) concentrations were measured simultaneously in the indoor and outdoor air of residences located in urban and sub-urban areas of northwestern Mainland Portugal. Average indoor to outdoor ratios (I/O) for OC were higher than 1 in occupied residences, showing that indoor sources, such as cooking, smoking, biomass burning and movement of people, strongly influenced indoor OC concentrations. In contrast, I/O ratios for EC were close to 1, except for a smokers’ residence, suggesting that indoor concentrations were mainly controlled by outdoor sources, most likely from vehicular emissions and biomass burning. Aerosol composition was also evaluated during one year in a kerbside site located in a busy road of Oporto. Road traffic, local dust and biomass burning were found to be the most important sources of aerosol particles. Most of the aerosol constituents exhibited well-defined temporal variations, which were related with the seasonal variability of source strengths, atmospheric processes and climatic conditions. In addition, precipitation samples were collected and characterized for chemical constituents at a background site in the Azores Islands and an urban site in the city of Oporto. Transport from continental areas bordering the North Atlantic Ocean were the main source of EC in the Azores. Both local emissions and long-range transport explained the levels of water soluble organic carbon found in the same samples. Concentrations of carbonaceous matter in Oporto were considerably higher than those measured before in other background areas in Portugal, indicating a significant atmospheric contamination by anthropogenic activities.
Nas últimas décadas foram desenvolvidos vários estudos sobre a circulação atmosférica da matéria carbonácea. Contudo, apesar dos esforços da comunidade científica, não se conseguiu ainda compreender detalhadamente a composição e a formação do aerossol carbonáceo no ar ambiente, o que reflete a grande variedade de fontes emissoras e a complexidade dos processos de transformação que ocorrem na atmosfera. Acresce ainda que se sabe muito pouco sobre um caso particular do aerossol de carbono: as partículas carbonáceas em suspensão no ar interior. Outra componente do ciclo do carbono que tem merecido pouca atenção da comunidade científica é a remoção das partículas carbonáceas da atmosfera. Este trabalho tem como objetivo principal contribuir para um melhor conhecimento sobre as fontes, processos de transformação e remoção da matéria carbonácea presente na atmosfera. As concentrações de matéria particulada, carbono orgânico (CO) e carbono elementar (CE) foram medidas simultaneamente no ar interior e exterior de residências localizadas em áreas urbanas e sub-urbanas da região nordeste de Portugal Continental. Os valores médios da razão entre as concentrações no ar interior e exterior (I/E) para o CO foram superiores a 1 para as residências com ocupantes, mostrando que as fontes interiores, como a confeção de alimentos, a queima de biomassa e o movimento de pessoas, influenciaram fortemente os teores de CO. Pelo contrário, obtiveram-se valores médios próximos de 1 para a razão I/E do CE, excluindo uma residência de fumadores, sugerindo que as concentrações deste componente eram controladas por fontes externas, muito provavelmente o tráfego automóvel e a queima de biomassa. A composição do aerossol foi também avaliada durante um ano num local confinante com uma estrada de tráfego intenso na cidade do Porto. Verificou-se que as principais fontes emissoras de partículas eram o tráfego automóvel, as poeiras do solo e a queima de biomassa. Muitos dos constituintes do aerossol mostraram variações temporais bem marcadas, as quais foram relacionadas com a variabilidade sazonal das fontes emissoras, dos processos atmosféricos e das condições climáticas. Procedeu-se ainda à recolha de amostras de precipitação e posterior caracterização química num local de fundo do arquipélago dos Açores e num local urbano da cidade do Porto. A principal fonte do CE nos Açores é o transporte a longas distâncias a partir das áreas continentais que envolvem o Atlântico Norte. Os teores de carbono orgânico insolúvel tiveram origem tanto em emissões locais como no transporte a longas distâncias. As concentrações de matéria carbonácea no Porto mostraram-se substancialmente superiores às que tinham sido medidas em áreas remotas de Portugal, indicando uma contaminação significativa por atividades antropogénicas.
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Puigcorbé, Lacueva Viena. "Use of 234Th:238U disequilibrium to estimate particulate organic carbon export in the upper ocean." Doctoral thesis, Universitat Autònoma de Barcelona, 2016. http://hdl.handle.net/10803/399280.
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L’exportació de carboni fixat mitjançant la fotosíntesi pel fitoplàncton, des de la superfície dels oceans a les
capes més profundes, és un component clau de la bomba biològica de carboni i, per extensió, del cicle global del
carboni, ja que manté els nivells de CO2 atmosfèrics per sota d’on es trobarien en l’actualitat si aquest procés no
es donés (Feely et al., 2001; Khatiwala et al., 2009; Parekh et al., 2006). El cicle de les partícules i la seva
exportació són també essencials pels cicles biogeoquímics d’altres macronutrients i espècies químiques de vital
importància per la biota marina, així com metalls i contaminants d’origen antropogènic.
El parell de radiotraçadors 234Th:238U ha estat utilitzat de forma extensa en l’estudi de l’exportació de partícules
i en la determinació de la força de la bomba biològica de carboni en els oceans (Coale and Bruland, 1985; Le
Moigne et al., 2013b). Aquesta tesi avalua els fluxos d’exportació de carboni als oceans i l’eficiència del segrest
de diòxid de carboni mitjançant processos biològics fent ús d’aquest parell de radiotraçadors naturals en diversos
règims oceanogràfics i sota contrastades condicions biogeoquímiques.
En primer lloc, la variabilitat de l’export a escala de conca oceànica va ser examinada a l’Atlàntic Nord-
Occidental al llarg d’un transsecte latitudinal (de 64ºN a l’equador) amb alta resolució espacial, proveint dades
addicionals en zones sub-mostrejades. Els resultats, que coincideixen amb estudis previs que varen tenir lloc al
Nord Atlàntic, van ser comparats amb diferents models d’exportació derivats de satèl·lits. Aquests models tenen
una forta dependència en les estimacions de temperatura superficial del mar i producció primària neta, però
normalment no consideren paràmetres biològics que influencien l’exportació de carboni, com ara l’estructura de
la xarxa tròfica, la intensitat de depredació, l’eficiència de reciclatge, l’activitat bacteriana o l’exportació de
carboni orgànic dissolt (Maiti et al., 2013). Les diferències observades entre les estimacions d’exportació de
carboni derivades dels models de satèl·lits o del mètode del 234Th posen de manifest la necessitat d’incloure
aquest tipus de paràmetres biològics a escala regional, per la qual cosa són necessaris esforços continuats
d’observació. La inclusió d’aquests paràmetres reduiria la incertesa de l’inventari de carboni global i milloraria
el monitoratge del cicle del carboni des de plataformes basades en satèl·lits.
En segon lloc, la zonació de les propietats de les aigües superficials derivades dels diferents fronts localitzats al
llarg d’un transsecte a 10ºE, de 44ºS to 53º S, en el Corrent Circumpolar Antàrtic va ser avaluada en relació amb
l’exportació de partícules. Els nostres resultats mostren com, malgrat el contrast en les xarxes tròfiques
observades al nord i al sud del Front Polar Antàrtic (~49ºS), la magnitud dels fluxos d’exportació de carboni era
similar al llarg del transsecte. Existien diferències, però, en examinar les eficiències de transferència: a la meitat
nord de la secció, la qual estava dominada per nanofitoplàncton, presentava eficiències d’exportació altes i
eficiències de transferència baixes en comparació a la meitat sud de la secció, dominada per microfitoplàncton.
Així doncs, malgrat que els diferents règims de xarxa tròfica donaren lloc a exportacions de carboni similars, el
conjunt de partícules que sedimentaven diferia en la seva composició entre el nord i el sud del Front Polar
Antàrtic (agregats de partícules petites en el nord vs partícules grans de sedimentació ràpida al sud), donant lloc
a dos escenaris diferents pel que fa a la quantitat de carboni exportat que arribà a les capes més profundes.
Per últim, les estimes del flux de partícules i l’eficiència d’exportació van ser examinades a una conca
semitancada (el Golf de California i les aigües adjacents del Pacífic Tropical Nord Oriental) amb una
estacionalitat molt marcada que va acompanyada de canvis en la comunitat fitoplanctònica. Les estimes
d’exportació es varen obtenir mitjançant el mètode del 234Th, juntament amb trampes de sediment. Les dades de
fraccionament per mides i l’alta ressolució vertical obtingudes amb bombes in situ van permetre la comparació
de l’atenuació amb la fondària de les ràtios C/234Th entre partícules petites (1-53 μm) i grans (>53 μm). El
resultats indiquen que, sota el domini de pico- i nanoplàncton i amb la presència de diazotrofs, les partícules
petites juguen un paper important en l’exportació de carboni i que aquest export, en la zona d’estudi en qüestió,
pot ser més eficient que l’export resultant d’una comunitat planctònica dominada per diatomees.The particulate export of photosynthetically fixed carbon from the surface ocean to the ocean interior by marine plankton is a key component of the biological carbon pump and, by extension, of the global carbon cycle as it helps to maintain atmospheric CO2 levels lower than would occur with out this process (Feely et al., 2001; Khatiwala et al., 2009; Parekh et al., 2006). Particle cycling and export are also essential for the biogeochemical cycles of other major nutrients and chemical species of vital importance for marine biota, as well as anthropogenic metals and pollutans. The radiotracer pair 234Th: 238U as been commonly and extensively used to study particle export and determine the strength of the biological carbon pump in the upper ocean (Coale and Bruland, 1985; Le Moigne et al., 2013b). This thesis evaluates oceanic carbon export fluxes and the efficiency of the biologically mediated uptake of atmospheric CO2 using this naturally occurring radiotracer pair in a variety of regimes under contrasting biogeochemical conditions. First, basin-scale export variability was examined in the North Western Atlantic Ocean along a latitudinal transect (from 64ºN to the equator) with high spatial resolution, providing additional data in under sampled areas. The results agreed with previous studies carried out in the North Atlantic and were also compared with different satellite-derived export models. These models have a strong dependence on sea surface temperature and net primary productivity estimates, but they usually do not consider biological parameters that influence carbon export, such as the trophic structure, the grazing intensity, the recycling efficiency, the bacterial activity and the dissolved organic carbon export (Maiti et al., 2013). The differences observed between the satellite-derived and the 234Th-derived carbon export estimates highlights the necessity to include such biological parameters at a regional scale, for which continued observing efforts are needed. This would thereby reduce uncertainty in the global carbon budget and improve carbon cycle monitoring from satellite-based platforms. Second, the zonation of surface properties derived from the various fronts crossed along a 10ºE transect, from 44ºS to 53ºS, in the Antarctic Circumpolar Current were evaluated in relation to particle export. Our results show that, despite the contrasting food webs encountered north and south of the Antarctic Polar Front (~49ºS), the magnitude of the carbon export fluxes were similar along the transect. However, differences appeared when examining transfer efficiencies: in the northern section, which was dominated by nanophytoplankton, presented high export efficiencies and reduced transfer efficiencies in comparison to the southern section, dominated by microphytoplankton. Thus, and although different food web regimes led to similar export of carbon, the sinking particle pools differed in their composition north and south of the Antarctic Polar Front (aggregates of small particles in the north vs fast-sinking large particles in the south), resulting in two different scenarios regarding the amount of exported carbon that reached greater depths. Finally, estimates of particle flux and export efficiency were examined in a semi-enclosed basin (Gulf of California and the surrounding waters of the Eastern Tropical North Pacific), with a strong seasonality that leads to changes in the planktonic community. Export estimates were assessed using the 234Th approach in combination with surface-tethered sediment traps. Data on size fractionation and high vertical resolution of in situ pump deployments allowed a comparison of the C/234Th ratios attenuation with depth between small (1-53 μm) and large (>53 μm) particles. Results indicate that, under dominance of pico- and nanoplankton and with presence of diazotrophs, small particles play and important role in carbon export and that this export might be more efficient than that resulting from a diatom dominated planktonic community in the study area.
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Perez-Castillo, Fernando. "Sedimentation of organic matter on the Hebridean slope." Thesis, Bangor University, 1999. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.287026.
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Ford, William Isaac III. "PARTICULATE ORGANIC CARBON FATE AND TRANSPORT IN A LOWLAND, TEMPERATE WATERSHED." UKnowledge, 2011. http://uknowledge.uky.edu/gradschool_theses/647.
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Small lowland agricultural systems promote conditions where benthic biological communities can thrive. These biogeochemical processes have significant impacts on terrestrial ecosystem processes including POC flux and fate, nutrient balances, water quality budges, and aquatic biological functioning. Limited information is available on coupled biological and hydrologic processes in fluvial systems. This study investigates the mixture of biological and hydrologic processes in the benthic layer in order to understand POC cycling in the South Elkhorn system. Further, comprehensive modeling of POC flux in lowland systems has not been performed previously and the behavior of potentially controlling variables, such as hydrologic forcing and seasonal temperature regimes, is not well understood. Conceptual hydraulic and sediment transport models were simulated for the South Elkhorn. Based on data and model results it was concluded that during a hydrologic event, upland and bank sources produce high variability of POC sources. Likewise, over time, the density of hydrologic events influenced accrual of benthic algal biomass in the POC pool. Environmental variables such as temperature and light availability drove seasonal variations of POC in the streambed. Based on model estimates, around 0.29 metric tCkm-2yr-1 of POC is flushed from the system annually with 13 % coming from autochthonous algae.
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Boubnov, Pavel Vladimirovitch. "Particulate organic carbon variability in the subarctic Pacific based on transmissometer data." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 2001. http://www.collectionscanada.ca/obj/s4/f2/dsk3/ftp04/MQ58527.pdf.
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Belcher, Anna Christine. "Controls on the attenuation of sinking particulate organic carbon in the mesopelagic." Thesis, University of Southampton, 2016. https://eprints.soton.ac.uk/407492/.
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The biological carbon pump plays a key role in regulating the ocean-atmosphere balance of CO2, without it atmospheric CO2 would likely be 200ppm higher than it is today. The most rapid attenuation of downward particulate organic carbon (POC) flux typically occurs in the upper few hundred meters of the water column, yet the practical difficulties of making measurements in this dynamic region of the ocean mean that the processes controlling POC flux attenuation are still poorly understood. In this thesis, Marine Snow Catchers were deployed in the Scotia Sea, Antarctica and the northeast Atlantic to obtain intact sinking particles and investigate the relationship between particle type and attenuation rate. Faecal pellets (FP) were a major component of the flux at all stations, yet total POC attenuation varied between sites in relation to zooplankton composition and bloom timing. A novel method was employed to characterise particle-associated microbial respiration on FP, which is currently a poorly understood term. Oxygen microsensors were used to measure small scale oxygen gradients through the boundary layer at the interface of FP. Rates of particle-associated microbial respiration were too low to account for the observed large decreases in FP flux over the upper 200 m, and evidence suggests that losses via zooplankton grazing and fragmentation are more important. The importance of Antarctic krill for setting the export efficiency of POC in the marginal ice zone (MIZ) of the Scotia Sea is highlighted through unique comparisons between observed mesopelagic krill FP fluxes and predicted surface FP production. Krill FP are transferred through the upper mesopelagic much more efficiently than values of POC attenuation typically used in global biogeochemical models. I conclude that improved, regionally specific knowledge of the zooplankton community composition is vital to understand global variations in POC flux attenuation, and hence allow better predictions of ocean carbon sequestration. Ultimately carbon is lost from the organic carbon pool as CO2 via respiration, and hence in theory, at steady state, the attenuation of POC should be balanced by community respiration. In reality this balance is difficult to achieve, suggesting that our understanding is incomplete. Very low rates of both absolute and carbon specific particle-associated microbial respiration (a term missing from previous budget studies) were measured on marine snow particles collected in the northeast Atlantic and hence cannot resolve imbalances in the upper mesopelagic POC budget. Microbial disaggregation and solubilisation of POC as well as fragmentation of large particles into slowly sinking and non-sinking POC by zooplankton, may help to explain imbalances in the carbon budget, highlighting the need to measure respiration losses on both fast, slow and non-sinking pools of POC.
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Nicoloso, Rodrigo da Silveira. "Estoques e mecanismos de estabilização do carbono orgânico do solo em agroecossistemas de clima temperado e sub-tropical." Universidade Federal de Santa Maria, 2009. http://repositorio.ufsm.br/handle/1/3574.
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Conselho Nacional de Desenvolvimento Científico e TecnológicoSoil carbon (C) sequestration in agriculture soil is a low cost option to mitigate global climatic change. No-till (NT) associated with good husbandry practices could compensate up to 15% of the anthropogenic CO2 emissions by storing the C from atmosphere as soil organic carbon (SOC). To be fully accepted as a mitigation alternative, research must be conducted to improve the accuracy of soil C sequestration estimates on field experiments as well as those made by mathematical models at regional and local scales. Complementarily, is necessary to improve the knowledge about the SOC stabilization mechanisms, delimiting the real soil´s capacity into accumulate C, quantifying how much of the stored C could be re-emitted to the atmosphere by changes in soil management. The present work is divided in four chapters with the objective to answer these questions. The first chapter has the objective to discuss the importance of sampling depth (0-0.30, 0-0.60, and 0-0.90 m) and the definition of a reliable and adequate baseline for the calculation of the C sequestration rates. Two long-term field experiments from a temperate (Mollisol) and a sub-tropical (Oxisol) climate soil were selected for this research. The experiments tested soil tillage systems (conventional tillage (CT) and NT) (Mollisol and Oxisol) and sources and rates of nitrogen amendment on corn in the Mollisol (control without N, 168 kg N ha-1 as ammonium sulfate, and 168 kg N ha-1 as organic fertilizer) and different crop rotation systems in the Oxisol (R0:soybean-wheat, R1:soybean-wheat-soybean-oat, and R2:soybean-oat-soybean-oat+vetch-corn-radish-wheat). The increase of sampling depth provided limited contribution to the estimates of C sequestration rates due to the increase of the error on SOC stocks estimates at deeper soil depths. To improve the C sequestration rate estimates, SOC temporal dynamic analysis should be preferred rather than the comparison of the SOC stocks of paired plots at a unique time point. The second chapter had the objective to apply simple mathematical equations to describe the SOC dynamics and improve the estimates of C sequestration rates and also to understand the role of the macroaggregate formation on SOC accumulation and saturation. The use of linear and kinetic (exponential growth) equation was adequate to describe the SOC dynamics increasing the accuracy of the C sequestration rate estimates by reducing errors promoted by soil spatial variability. The SOC accumulation was a function of the amount of C input to the soil and the macroaggregate formation to protect SOC. The SOC saturation process occurred from the smaller to the larger aggregate size fraction, limiting the capacity of a given superficial soil layer to accumulate SOC. However, the SOC saturation at superficial soil layers did not indicate the end of C sequestration in the soil, since the SOC accumulation occurred at sub-superficial soil layers. In the third chapter, the mathematical approach to determine changes on SOC stocks and the SOC saturation-induced limitation for C sequestration were applied to improve the accuracy of the Hénin e Dupuís (1945) one- 8 compartmental mathematical model into predict future soil C sequestration rates. The long-term field experiment from the Mollisol was selected for this research because of the better data availability (sampling years) and also by the presence of two treatments under CT and NT with SOC saturated soil layers. The mathematical adjustment (by linear equations) of the SOC dynamic coefficients improved the adjustment of the model‟s predictions. The SOC saturation-induced restriction for SOC accumulation on the mathematical model avoided the overestimation of the soil‟s potential for C sequestration. The predictions of the mathematical models indicate that the Mollisol‟s superficial layer (0-0.05 m) under NT could maintain significant C sequestration rates for up to 50 years as a function of the amount of C input to the soil. For the fourth chapter, a detailed study of the SOC pools in water-stable aggregate size fractions by granulometric and densimetric fractionation was carried out. The objective was to identify the pools where SOC accumulation was occurring and what SOC stabilization mechanisms were present. This will provide estimates of the NT potential to promote long-term C sequestration. SOC accumulation occurred preferentially in the more stable and recalcitrant SOC fractions (Mollisol and Oxisol) or in microaggregate and macroaggregate physically protected fractions (Mollisol). In the Oxisol, the SOC enrichment occurred mostly in the mineral associated-SOC fractions extra-microaggregates occluded within meso- and macroaggregates, while in the Mollisol, the SOC accumulation occurred in both intra- and extra-microaggregate mineral associated-SOC fractions. More than 78 and 92% of the C sequestration verified in the Mollisol and Oxisol, respectively, were considered as long-term by occurring in stable SOC fractions.
O seqüestro de carbono (C) em solos agrícolas é uma opção de baixo custo para mitigação das mudanças climáticas globais. O plantio direto (PD), associado a boas práticas agronômicas, pode compensar até 15% das emissões antrópicas de CO2 ao armazenar o C drenado da atmosfera na forma de carbono orgânico (CO) do solo. Para ser amplamente aceito como alternativa de mitigação, pesquisas devem ser conduzidas a fim de melhorar a precisão das estimativas de taxas de seqüestro de C em experimentos de campo, assim como as previsões feitas por modelos matemáticos em escalas regionais e locais. Complementarmente, é necessário aprimorar o conhecimento sobre os mecanismos de estabilização do CO, delimitando a capacidade real do solo em acumular C e quantificando quanto do C acumulado no solo pode ser re-emitido para atmosfera por mudança no manejo do solo. Desta maneira, o presente trabalho se divide em quatro capítulos com o objetivo de abordar estas questões. O primeiro capítulo tem por objetivo discutir a importância da profundidade de amostragem (0-0,30; 0-0,60; 0-0,90 m) e da definição de situações de linhas-base confiáveis a adequadas para o cálculo das taxas de seqüestro de C. Para isto, foram utilizados dois experimentos de longa duração sobre um solo de clima temperado (Mollisol) e outro de clima sub-tropical (Oxisol). Os experimentos testaram efeitos de sistema de preparo do solo (preparo convencional (PC) e PD) (Mollisol e Oxisol) e fontes e doses de nitrogênio para o milho no Mollisol (testemunha (T), 168 kg N ha-1 na forma de sulfato de amônia (AM) e 168 kg N ha-1 na forma de adubo orgânico (AO)) e diferentes sistemas de rotação de culturas no Oxisol (R0:soja-trigo, R1:soja-trigo-soja-aveia e R2:soja-aveia-soja-aveia+ervilhaca-milho-nabo-trigo). O aumento da profundidade de amostragem não contribuiu com a melhoria das estimativas de taxas de seqüestro de C devido ao aumento do erro nas estimativas dos estoques de CO nas camadas mais profundas de solo. Para melhoria das estimativas das taxas de seqüestro de C devem-se preferir análises temporais da dinâmica do CO no solo ao invés da comparação de estoques de CO em um único momento. O segundo capítulo tem por objetivo aplicar equações matemáticas simples para descrever a dinâmica do CO e melhorar as estimativas taxas de seqüestro de C e também entender o papel da formação de macroagregados no acúmulo e saturação de CO no solo. O uso de equações lineares e cinéticas (crescimento exponencial) foi adequado para descrever a dinâmica do CO, aumentando a precisão das estimativas de taxas de seqüestro de C ao reduzir os erros de estimativa por variabilidade espacial do solo. O acúmulo de CO no solo mostrou-se uma função da quantidade de C aportada ao solo por resíduos vegetais e a formação de macroagregados no solo para proteção do CO. O processo de saturação do solo ocorreu das menores para as maiores frações de agregados do solo, limitando a capacidade de uma 6 determinada camada de solo em acumular CO. No entanto, verificou-se que a saturação de camadas superficiais de solo não indica o fim do seqüestro de C neste solo, visto que o acúmulo de CO passa a ocorrer em camadas sub-superficiais. No terceiro capítulo, a aproximação matemática para determinar mudanças nos estoques de CO e a limitação na capacidade do solo em acumular CO promovida pelo processo de saturação dos agregados do solo foram aplicados para melhorar a precisão do modelo matemático uni-compartimental de Hénin e Dupuís (1945) em prever futuras taxas de seqüestro de C. O Mollisol foi escolhido para este estudo em função da maior disponibilidade de dados (anos de amostragem) e também pela presença de dois tratamentos em PC e PD com camada de solo saturada por CO. O ajuste matemático (por equações lineares) dos coeficientes da dinâmica do CO melhorou o ajuste das previsões do modelo com os dados observados. A restrição do modelo matemático quanto à capacidade do solo em acumular CO (saturação de CO) evitou a superestimação do potencial de seqüestro de C deste solo. As previsões do modelo matemático indicam que a camada superficial (0-0,05 m) do solo sob PD pode apresentar taxas significativas de seqüestro de C por até 50 anos, em função da quantidade de C adicionada ao solo. No quarto capítulo, foi realizado um estudo detalhado dos compartimentos do CO em função da sua distribuição em classes de tamanhos de agregados estáveis em água e o fracionamento granulométrico e densimétrico do CO. O objetivo foi identificar em quais compartimentos está ocorrendo o acúmulo de CO no solo, os mecanismos de estabilização do CO, estimando o potencial do PD em promover sequestro de C de longa duração. Verificou-se que o acúmulo de C ocorre preferencialmente em frações mais estáveis e recalcitrantes do CO (Mollisol e Oxisol) ou em frações protegidas fisicamente por micro e macroagregados (Mollisol). No Oxisol, o enriquecimento de CO ocorre principalmente nas frações de CO associadas aos minerais extra-microaggregados oclusas em meso e macroagregados de solo, enquanto que no Mollisol, o acumulo de CO ocorre tanto na fração intra como extra microagregados. Mais de 78 e 92% do seqüestro de C verificado no Mollisol e Oxisol, repectivamente, foi considerado de longa duração por ocorrer em frações estáveis do CO.
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Clark, Kathryn Elizabeth. "Patterns and drivers of riverine particulate organic carbon transport in an Andean valley." Thesis, University of Oxford, 2014. http://ora.ox.ac.uk/objects/uuid:caabfe4f-7499-4789-9bdc-e1dc708999a0.
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Physical erosion can mobilise particulate organic carbon (POC) from vegetation and soil, representing an export of primary productivity from ecosystems, and a lateral transfer of carbon recently-derived from the atmosphere. These carbon transfers are thought to be enhanced in mountain forests where erosion rates are high. However, the rates and controls on POC transfer remain poorly constrained, as does the impact of POC export on carbon cycling at regional and global scales. This thesis takes an interdisciplinary approach to address this issue, using remote sensing, river geochemistry, river hydrology, and geomorphic mapping in the Kosñipata Valley, in the Central Andes of Peru. Its main aims are to: 1) estimate stream discharge throughout the year and to evaluate the water balance and sources; 2) quantify the source of riverine POC, accounting for POC derived from sedimentary rocks (POCfossil) to examine the POC eroded from soils and vegetation (POCnon-fossil); 3) quantify river POC yields; 4) assess the hillslope processes that erode POC; and 5) assess how POC export impacts the carbon balance of mountain forest, and how fluvial transfer impacts the wider carbon cycle. Stream flow was monitored from January 2010 to February 2011 at two newly installed river gauging stations in the Kosñipata Valley at 2250 m (Wayqecha, 48.5 km2) and 1360 m (San Pedro, 164.4 km2). Then annual water balance for the San Pedro catchment was quantified. Rainfall inputs of 3028 mm and cloud water inputs of 308 ± 97 mm were balanced by outputs via stream runoff (2721 mm) and actual evapotranspiration (907 mm), leaving a residual of -294 ± 97 mm (< ~10 % of water inputs). The source of POC in river suspended sediment samples was quantified using radiocarbon (Δ14C, ‰), stable carbon isotopes, and the nitrogen to carbon ratio. This revealed that river POCnon-fossil was sourced from very young organic carbon in the valley (Δ14C ~50 ‰) and that POCfossil comprised 43 % of total POC. Combining the hydrometric measurements with river samples, annual particulate load fluxes were quantified. The vast majority (73 % to 77 %) of the annual suspended sediment transfer and POC (both POCfossil and POCnon-fossil) occurred in the wet season over a period of 4 months. The suspended sediment yield for the valley (960 – 1200 t km-2 yr-1) was consistent with those for the Andean portion of the Madre de Dios River into which the Kosñipata River drains. The river POCnon-fossil yield was 5.2 – 6.9 tC km-2 yr-1. Landslides are likely to have played an important role in the mobilisation of POCnon-fossil. A detailed landslide mapping using 25 years of remote sensing data revealed that on average 0.09 % of the valley per year is impacted by this mass-wasting process. These landslides mobilise ~28 tC km-2 yr-1 of soil and vegetation valley-wide. The discrepancy between the landslide erosional flux and fluvial POCnon-fossil export suggests an important fraction of the POCnon-fossil harvested by landslides is either exported as coarse debris (not quantified in the fluvial POCnon-fossil flux), remains buried onsite, or is degraded and respired onsite. Landslides also played an important ecosystem function, turning over some sections of the mountain forest within ~625 years, with a 1200 year valley-wide mean. On the basin scale, the Madre de Dios River drains ~ 6 % of the Amazonian Andes. This study enables estimation of the delivery of POC to the lowland Amazon Basin. Using the observation that POCnon-fossil and POCfossil fluxes were closely linked with suspended sediment transfer, total yields of ~0.22 MtC yr-1 and ~0.17 MtC yr-1, respectively, were estimated from this section of the Andes. The export of POCnon-fossil from mountain forests by rivers represents 0.4 – 1.0 % yr-1 of the net primary productivity of Andean forest and so even if only a small portion of this is buried in sedimentary deposits, it may promote the Andes as a carbon sink. These results demonstrate the long-term influence of erosional processes in the cycling of carbon in the Amazon Basin.
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Cavan, Emma. "Sink or swim : the fate of particulate organic carbon in the interior ocean." Thesis, University of Southampton, 2016. https://eprints.soton.ac.uk/401166/.
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Without small oceanic organisms atmospheric CO2 levels would be about 200 ppm higher than they are today; phytoplankton convert dissolved inorganic carbon (DIC) to particulate organic carbon (POC) during photosynthesis, influencing the air-sea exchange of CO2. Eventually some of this POC is exported out of the upper ocean, often as either phytodetrital aggregates or zooplankton faecal pellets. Because of the complexity of this biological carbon pump (BCP), the fate of the exported POC in the mesopelagic zone is difficult to predict. To make things more complex all of these processes vary temporally and spatially. Marine snow catchers (MSCs) were used to analyse fast and slow sinking particles separately, which is a unique approach as slow sinking POC fluxes are not often quantified. To investigate what controls the fate of particles in the upper mesopelagic zone (50 - 500 m) particles were collected from three contrasting oceanic regions: the Southern Ocean (SO), Equatorial Tropical North Pacific (ETNP) oxygen minimum zone (OMZ) and the temperate North Atlantic. In all sampling areas the slow sinking POC flux was as large if not larger than the fast sinking POC flux. This emphasises the importance of slow sinking particles in the upper mesopelagic zone. The main outcome from this thesis is the importance of the role of zooplankton in BCP processes. For instance the efficiency which particles were exported from the mixed layer varied inversely with primary production in the SO, and was likely due to the zooplankton grazing down the phytoplankton. When extending the data to include the ETNP and the North Atlantic this relationship still held, conflicting the long-standing theory that as primary production increases export efficiency increases. In the ETNP oxygen minimum zone a high proportion of exported POC sank through the mesopelagic zone. Microbial oxygen uptake incubations showed for the first time that fast sinking particles are turned over significantly slower than slow sinking particles (0.13 d?1 and 5 d?1 respectively). Microbial degradation of POC could explain most of the fast sinking POC attenuation with depth, with the remainder lost due to abiotic fragmentation. Therefore it is likely that zooplankton degradation of particles is reduced in OMZs as their abundance and metabolism are lowered. This reduces the overall remineralistion of POC, hence a higher fraction of POC is transferred to depth in OMZs. Phytoplankton lipid biomarkers dominated lipid particle composition throughout the upper mesopelagic zone in the ETNP, further emphasising the minor role of zooplankton in OMZs. Comparing the observations with an ecosystem model output at all three oceanic sites further emphasised the importance of zooplankton in the BCP. The model poorly parameterises zooplankton processing of particles and thus the observations and model matched best in the ETNP, where zooplankton processing of particles is naturally low. Changes in climate will effect the abundance and distribution of these small organisms. Further understanding of how zooplankton community structure and metabolism may change in the future will be important to predict how atmosphericCO2 levels may change.
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Oyelami, Ayodeji Oluwaseun. "Impact of nano- and micro-particulate black carbon on organic contaminant bioaccessibility in soil." Thesis, Lancaster University, 2013. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.663215.
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This thesis investigated the impacts of different forms of black carbon (BC) on the bioavailability and bioaccessibility of phenanthrene in soil for remediation. BC is a general term used to describe various forms of natural and engineered carbonaceous geosorbents, such as activated carbon (AC), biochar and soot. Carbon nanomaterials (CNMs) are generally agreed to be engineered structures with at least one dimension of less than 100 nanometres in length. CNMs are of interest because of their specific physicochemical properties that can be attributed to their small size, chemical composition, surface structure, solubility, shape and aggregation. CNMs could be released into water and soil not only by inadvertent discharge, but also because NPs have applications for groundwater purification and pollutant remediation. Unfortunately, very little is known about the transport of these materials in soil or the resulting ecotoxicity, and only a small number of studies have been carried out in this area. Phenanthrene, a ubiquitous, persistent and hydrophobic contaminant found in all ecosystems worldwide, was used as the target contaminant for the studies carried out in this thesis. Powdered activated carbons (PACs) with different pore volumes and particle size distributions were amended to soil, and used to assess bioaccessibility of phenanthrene to soil. Biochar from the same feedstock was also used, but prepared under different conditions. At low concentrations (0.01 %), the addition of AC to soil did not affect microbial activity, measured by the rates of respiration and overall extents of mineralisation of 14C-phenanthrene. However, the presence of AC at 0.1 and 1 %, respectively, resulted in significant reductions (P < 0.05) in the bioavailability and bioaccessibility of 14C_ phenanthrene. For CNM-amended soils, the addition of>0.01% (w/w) significantly reduced the development of phenanthrene catabolism; the only exception to this was C60, which did not show any significant difference from the control, at all concentrations. Results from this thesis suggest that soils amended with AC provide a potential strategy for in situ environmental remediation, and appropriate selection of adsorbents is a key to realising this remediation potential. The different kinds of BC described in this thesis provide a wide choice; therefore it is reasonable to regard them as a promising amendment technology.
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Tucker, Ashley. "GLOBAL ASSESSMENT OF RADIOCARBON ISOTOPIC ANALYSIS FOR PARTICULATE AND DISSOLVED ORGANIC CARBON IN RIVERINE SYSTEMS." VCU Scholars Compass, 2014. http://scholarscompass.vcu.edu/etd/632.
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Rivers are a significant source of particulate and dissolved organic carbon (POC, DOC) into inland waters and coastal systems and provide a fundamental linkage between the terrestrial, oceanic, and atmospheric carbon reservoirs. Recent studies have examined the relationship between the quantity and form (POC vs. DOC) of carbon delivered to the aquatic system; however, little is known about the age of POC and DOC exported and how the radiocarbon age may vary with latitude, topographic gradient, vegetation, and land use. I provide the first global synthesis of published radiocarbon values of POC and DOC (∆14C). Inclusion of DOC and POC parameters (µM, δ13C, ∆14C) reveal significant driving forces of DOC (µM), latitude, and elevation (m) as capable of explaining 25% of the variability in DO14C in rivers and POC (µM) and latitude accounting for 15% of the variability in PO14C. When δ13C of DOC and POC and latitude were incorporated with ∆14C of DOC observations, 61% of the variability in DOC age was explained revealing the necessity to include dissolved and particulate fractions of organic carbon to yield the most robust predictive models. This study found a global trend of increasing age of DOC and increasing δ13C of DOC and POC with increasing latitude. My study suggests future research should incorporate both particulate and dissolved OC parameters along with elevation, vegetation, land cover, and climate zones to increase understanding of what drives the age of carbon exported in riverine systems.
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Hanks, Karari O. "Water insoluble particulate organic and elemental carbon concentrations and ionic concentrations from snowpits obtained at Summit, Greenland." Thesis, Available online, Georgia Institute of Technology, 2004:, 2003. http://etd.gatech.edu/theses/available/etd-04082004-180212/unrestricted/hanks%5Fkarari%5Fo%5F200312%5Fms.pdf.
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Gelfond, Claudia E. (Claudia Elisabeth). "Photochemical transformation of particulate organic carbon and its impact on mercury cycling in aqueous systems." Thesis, Massachusetts Institute of Technology, 2017. http://hdl.handle.net/1721.1/115459.
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Thesis: S.M. in Environmental Engineering, Massachusetts Institute of Technology, Department of Civil and Environmental Engineering, 2017.Cataloged from PDF version of thesis. Errors in Table of Content. Pagination reflects how thesis was delivered to MIT LIbraries.
Includes bibliographical references (pages 35-37).
Mercury (Hg) is a global pollutant with high toxicity that accumulates in biota and biomagnifies, posing a risk to organisms throughout the food chain. Mercury is known to strongly associate with natural organic matter (NOM), which, in turn, affects its speciation, solubility, mobility and toxicity. Numerous studies have examined Hg coordination with dissolved organic carbon (DOC), an important aqueous constituent that alters the reactivity and fate of Hg primarily through complexation with carboxyl and reduced sulfur (e.g. sulfhydryl) groups. However, less is understood of Hg reactions with particulate organic matter (POM), an important reservoir of NOM found within soils, sediments, and suspended in aqueous systems. Moreover, the chemistry of NOM changes when irradiated by sunlight, altering the composition and distribution of functional groups available for complexation with aqueous Hg. Accordingly, we investigate Hg complexation with POM derived from a natural source, Phragmites australis ("common reed"), and examined how photochemical processes impact Hg adsorption through chemical alteration of POM. Mercury adsorption to irradiated and non-irradiated POM was examined through performing isotherm experiments, using an environmentally-relevant range of Hg concentrations (2-500 ppb). First, we find that non-irradiated POM is a powerful sorbent of Hg²+. Adsorption characteristics are indeed altered during POM photolysis, with a three-fold (based on Kd) increase in Hg adsorption observed for irradiated POM compared to dark controls. Further, we examine the speciation and oxidation state of adsorbed Hg²+, and deciphered functional groups that contribute to mercury association with POM. Measurements of C, S, and Hg speciation and oxidation state were performed using synchrotron-based X-ray adsorption spectroscopy (XAS) and scanning transmission x-ray microscopy (STXM). These revealed a marked decrease in POM-reduced sulfur following irradiation, leading to fewer R-SH groups capable of strongly binding Hg. However, decreased Hg binding to irradiated POM was not observed owing to a large increase in the quantity of carboxyl groups formed through photochemical processes, which resulted in a higher overall capacity of irradiated POM to bind Hg. The large capacity of POM for binding Hg, as well as enhanced Hg binding following irradiation illustrates that POM is a chemically dynamic pool of NOM that warrants consideration when evaluating reservoirs and processes governing the global Hg cycle.
by Claudia E. Gelfond.
S.M. in Environmental Engineering
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Condon, Katherine Elyse. "Quantifying Catchment-Scale Particulate Organic Matter (POM) Loss Following Fire, Relative to Background POM Fluxes." Thesis, The University of Arizona, 2013. http://hdl.handle.net/10150/301557.
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This study investigates translocation of particulate carbon and nitrogen from burned and unburned catchments within New Mexico's Valles Caldera National Preserve following severe wildfire. My research questions are: (1) how much carbon and nitrogen is eroded from burned slopes and re-deposited in debris fans? and (2) how do these quantities compare to fluvial export of particulate carbon and nitrogen from nearby unburned catchments? Results indicate that the ~200 kg ha⁻¹ of nitrogen per depositional area on the debris fans represents ~50 to 100 years' worth of atmospheric inputs. In total, 124 times more carbon and 21 times more nitrogen were deposited on the two fans than was exported in particulate form from all three unburned catchments combined in water year 2012. My findings suggest that post-fire erosion may increase nitrogen loading to downslope environments, with the potential to alter the biogeochemical budgets of both aquatic and terrestrial systems.
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Kelsey, Scott Alan. "Impact of Land Use on Headwater Stream Organic and Inorganic Carbon Export in a Temperate Midwestern Experimental Watershed." The Ohio State University, 2016. http://rave.ohiolink.edu/etdc/view?acc_num=osu1460651004.
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Estrela, Sílvia Regina Marques Faria. "Wildfire effects on forest soil organic matter stocks and losses by runoff." Doctoral thesis, Universidade de Aveiro, 2016. http://hdl.handle.net/10773/19151.
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Doutoramento em Ciências e Engenharia do AmbienteO solo é considerado o maior reservatório de carbono (C) global e, um importante sumidouro de CO2 atmosférico. Os incêndios florestais são um fenómeno frequente nos ecossistemas mediterrânicos, em especial em Portugal. Nas últimas décadas verificou-se um aumento do número de incêndios e os cenários de alterações climáticas sugerem que os regimes de incêndios se poderão intensificar no futuro. Os incêndios florestais podem provocar efeitos importantes a curto e médio prazo em fatores chave da qualidade do solo, tais como a quantidade e qualidade da matéria orgânica (SOM). Devido à grande quantidade de carbono (C) armazenado no solo, mesmo pequenas mudanças na SOM poderão ter um efeito significativo sobre os ciclos biogeoquímicos e, consequentemente, sobre o clima global. Embora existam vários estudos que documentam os efeitos pós-fogo sobre os processos hidrológicos e de erosão, em termos de impactos sobre a quantidade (em termos de stocks e perdas de carbono orgânico (OC) por escorrência superficial), qualidade da SOM e sedimentos exportados, bem como a sua recuperação pós-fogo tem sido pouco estudados. Estes foram os principais objetivos deste estudo, realizado em plantações de eucalipto (Eucalyptus globulus), um dos tipos de vegetação florestal mais suscetíveis ao fogo no centro-norte de Portugal. O efeito dos incêndios florestais na qualidade da SOM do solo foi avaliado na camada superficial do solo (0-2 cm) em 4 períodos de amostragem, imediatamente antes das primeiras chuvas até dois anos após o incêndio. Para tal, foram utilizadas várias técnicas analíticas, tais como a deteção e caraterização de biomarcadores lipídicos por cromatografia gasosa/espetrometria de massa (GC-MS), caraterização de SOM por pirólise acoplada à cromatografia gasosa e à espetrometria de massa (Py-GC/MS) e, por ressonância magnética nuclear 13C de estado sólido (13C NMR). As exportações pós-fogo de OC por escorrência superficial e as respetivas contribuições das frações de carbono orgânico dissolvido (DOC), carbono orgânico particulado (POC) e carbono inorgânico dissolvido (DIC) foram também determinados em amostras de escorrência superficial recolhidas em intervalos de 1 a 2 semanas ao longo do primeiro ano após o incêndio. Os resultados mostraram que o incêndio provocou mudanças consideráveis na quantidade e qualidade da SOM. Estas incluíram a degradação térmica e quebra de compostos de n-alquilo. Aumentaram os rácios das cadeias curto-longo de n-alcanos e das cadeias de n- FAMEs, assim como a alteração dos respetivos índices. Além disso, a abundância relativa de certos biomarcadores específicos de determinadas plantas foram modificados, especialmente diminuição de terpenóides, tais como epiglobulol, ledol e globulol que são característicos do Eucalyptus globulus. Outras diferenças observadas no solo queimado foram a presença de levoglucosano, um marcador típico para a alteração térmica de polissacarídeos, maior abundância relativa de compostos derivados da lenhina (vanilina e metoxifenol) e a presença de estruturas de N-heteroaromáticos. Os espetros de 13C NMR também indicaram que o fogo produziu um aumento considerável na aromaticidade e condensação aromática da SOM. Estas diferenças verificaram-se durante o período de estudo, sugerindo uma lenta recuperação das propriedades do solo, possivelmente influenciadas, quer por uma recuperação limitada da vegetação, quer pela intensificação das perda de solo após o incêndio. O presente trabalho abordou também um tema pouco estudado como são os efeitos pós-fogo nas perdas de OC no solo por escorrência superficial. Os principais resultados apontaram para (i) uma maior quantidades de cinzas na encosta orientada a norte do que na encosta orientada a sul, enquanto que para a quantidade total de carbono orgânico (TOC) nas cinzas, estas não apresentaram diferenças; (ii) quer a perda total de sedimentos, quer a quantidade TOC do solo apresentouse maior na encosta orientada a norte do que a sul; (iii) a fração de OC que apresentou as maiores perdas, para ambas as encostas, foi a particulada. A quantificação das perdas de OC pós-fogo podem contribuir de forma relevante para a proteção dos ecossistemas, nomeadamente em termos da fertilidade do solo.
Soil is considered the largest carbon reservoir and an important global sink for atmospheric CO2. Wildfires are frequent in Mediterranean ecosystems, especially in Portugal. In recent decades there has been an increase in the number of fires and climate change scenarios suggest that the fire regimes are likely to increase in the future. Forest fires can have important short−to long−term implications for key aspects of soil quality, such as the quantity and quality of soil organic matter (SOM). Due to high amount of carbon (C) stored in soil, even slight alterations of SOM can affect significantly biogeochemical cycles, hence, affecting the whole global climate. Although numerous studies have documented the effects of wildfires on hydrological and erosion processes, the effects of fire on the quantity (in terms of stocks and losses of OC content by overland flow) and quality of SOM and in the sediments eroded, as well on postfire SOM recovery, have received considerably less research attention. These were the principal goals of the present study conducted on eucalypt plantations, one of the most fire-prone forest types in northcentral Portugal. The effects of wildfires on quality of SOM was evaluated in topsoil samples (0-2 cm) on four sampling occasions, starting immediately after the first post-fire rain till two years later. It was necessary a combination of multi-analytical techniques, such as lipid-biomarker analysis by gas chromatography-mass spectrometry (GC-MS), SOM characterization by pyrolysis-gas chromatography/mass spectrometry (Py-GC/MS) and solid state 13C nuclear magnetic resonance (13C NMR) spectroscopy. Post-fire OC exports by overland flow and the contributions of the dissolved organic carbon (DOC), particulate organic carbon (POC) and dissolved inorganic carbon (DIC) fractions were measured in runoff samples collected at 1- to 2- weekly intervals during the first year after the wildfire. The results showed that wildfire produced substantial changes in the quantity and quality of SOM. These included the thermal breakdown and cracking of n-alkyl compounds. Ratios of short-to-long n-alkanes and n-fatty acid methyl esters (FAMEs) increased and typical carbon number predominance indexes for n-alkanes (odd-to-even) and n-FAMEs (evento- odd) were altered. Furthermore, the relative abundances of certain markers, which are plantspecies specific were modified, especially by decreasing terpenoids such as epiglobulol, ledol and globulol, which are characteristic of Eucalyptus globulus. Other differences observed in the burnt soil were the appearance of levoglucosan, a typical marker for the thermal alteration of polysaccharides, larger relative abundances of lignin-derived compounds (vanillin and methoxyphenols) and the presence of N-heteroaromatic structures. The 13C NMR spectra also indicated that the wildfire produced a considerable increase in the aromaticity and aromatic condensation of the topsoil SOM. The continuation of these differences in SOM quality during the period of this study, suggested a slow recovery of soil properties, possibly influenced by a limited recovery of the vegetation after the fire combined with the fire-enhanced losses of soil. The present work also evaluated post-fire soil OC losses by overland flow in recently two burnt eucalypt plantations, addressing a topic that has seldom been investigated. The main findings were that: (i) the amount of deposited ashes was higher at the NW slope than at the SE slope, while ashes total organic carbon (TOC) content revealed no differences; (ii) total sediment losses and also the TOC export were higher at the NW slope than at the SE slope; (iii) particulate organic carbon fraction showed the highest loss at the both topsoil sites. In addition, this study provides some insight into post-fire organic carbon losses in the recently burnt areas, which is crucial information for ecosystem management, especially in terms of soil fertility.
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Li, Jinling. "Effects of Biosolids on Carbon Sequestration and Nitrogen Cycling." Diss., Virginia Tech, 2013. http://hdl.handle.net/10919/49585.
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Land application of biosolids has been demonstrated to improve nutrient availability (mainly N and P) and improve organic matter in soils, but the effects of biosolids on C sequestration and N cycling in the Mid-Atlantic region is not well understood. The objectives were: 1) to investigate soil C sequestration at sites with a long-term history of biosolids either in repeated application or single large application; 2) to characterize and compare soil C chemistry using advanced 13C nuclear magnetic resonance (NMR) and C (1s) near edge x-ray absorption fine structure (NEXAFS) spectroscopic techniques; and 3) to compare biosolids types and tillage practices on short-term N availability in the Coastal Plain soils. Biosolids led to C accumulation in the soil surface (< 15 cm) after long-time application in both Piedmont and Coastal Plain soils. The C saturation phenomenon occurred in Coastal Plain soils, thus additional soil C accumulation was not achieved by increasing C inputs from biosolids to the Coastal Plain. Soil organic C from profiles in the field sites was not different at depths below the plow layer (15-60 cm). The quantitative NMR analyses concluded that O-alkyl C was the dominant form in the particulate organic matter (POM), followed by aromatic C, alkyl C, COO/N-C=O, aromatic C-O, OCH3 / NCH and ketones and aldehydes. The aliphatic C and aromatic C were enriched but the O-alkyl C was decreased in the biosolids-amended soils. The changes indicated that the biosolids-derived soil C was more decomposed and, thus, more stable than the control. The NEXAFS spectra showed that O-alkyl C was the dominant form in the POM extracted from biosolids-amended soils, followed by aromatic C, alkyl C, carboxylic C and phenolic C groups. These results were similar to those from NMR analysis. The regression and correlation analyses of C functional groups in the POM between NEXAFS and NMR indicated that both techniques had good sensitivity for the characterization of C from biosolids-amended soils. To evaluate short-term biosolids N availability, a three-year field study to investigate the effects of lime-stabilized (LS) and anaerobically digested (AD) biosolids on N availability in a corn-soybean rotation under conventional tillage and no-tillage practices was set up in 2009-2011. Results showed that both LS and AD biosolids increased spring soil nitrate N, plant tissue N at silking, post-season corn stalk nitrate N, grain yield, and soil total N by the end of the growing season. The same factors used to calculate plant available N for incorporated biosolids can be used on biosolids applied to no-till systems in coarse-textured soils. All these results indicated that the application of biosolids affects the long-term quantification and qualification of soil organic C and also improve short-term N availability in the Mid-Atlantic region.Ph. D.
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Lee, Mi-Hee [Verfasser], and Egbert [Akademischer Betreuer] Matzner. "Dynamics of dissolved and particulate organic carbon and nitrogen in forest ecosystems / Mi-Hee Lee. Betreuer: Egbert Matzner." Bayreuth : Universität Bayreuth, 2016. http://d-nb.info/1095663623/34.
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Thomalla, S. J. "Particulate organic carbon and mineral export from the North and South Atlantic gyres : the 234Th/238U disequilibrium approach." Doctoral thesis, University of Cape Town, 2007. http://hdl.handle.net/11427/6452.
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Includes bibliographical references (leaves 228-270).Subtropical ocean gyres are typically characterised by low carbon export into the deep ocean. However, due to their large area, even relatively small average carbon export may be globally significant. Strong correlations observed between deep-sea organic carbon, calcite and opal suggest that mineral phases may enhance the export and survival of organic matter as it sinks (the 'ballast effect'). However, the processes underlying these correlations are not well understood and remain key uncertainties in models that predict global carbon cycling. To better constrain carbon and mineral export from the surface ocean of subtropical gyres, radioactive disequilibria between 234Th and 238U were used to estimate fluxes of particulate organic carbon (POe), calcite and opal in the North and South Atlantic subtropical gyres.
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Vonk, Jorien Elisabeth. "Molecular and isotopic characterization of terrestrial organic carbon released to (sub-)Arctic coastal waters." Doctoral thesis, Stockholm : Department of Applied Environmental Science (ITM), Stockholm University, 2010. http://urn.kb.se/resolve?urn=urn:nbn:se:su:diva-38589.
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Diss. (sammanfattning) Stockholm : Stockholms universitet, 2010.At the time of the doctoral defense, the following paper was unpublished and had a status as follows: Paper 3: Accepted. Paper 4: Manuscript. Härtill 4 uppsatser.
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Kuppili, Sudheer Kumar. "Biodiesel Properties and Characterization of Particulate Matter Emissions from TARTA Buses Fueled by B20 Biodiesel." University of Toledo / OhioLINK, 2016. http://rave.ohiolink.edu/etdc/view?acc_num=toledo1471631394.
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Guse, Paige Marie. "VOC Interference with Standard Diesel Particulate Analysis for Mine Samples: Exploring Sources and Possible Solutions." Thesis, Virginia Tech, 2020. http://hdl.handle.net/10919/97993.
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Exposure to diesel engine exhaust is linked to chronic and acute illness. In underground mines, workers can be exposed to high concentrations for extended periods of time. Therefore, Mine Safety and Health Administration (MSHA) enforces personal exposure and engine emission limits. These regulations target just the solid portion of diesel exhaust, known as diesel particulate matter (DPM). The majority of DPM mass is attributed to particulate organic carbon (POC) and elemental carbon (EC). Total carbon (TC) is the sum of POC and EC and currently used as the surrogate to represent DPM as a whole.
The NIOSH Method 5040 is the standard sample collection and analysis procedure. It outlines collection of submicron particulate matter samples on a quartz filter then measurement of POC and EC using a thermal-optical analysis. Error in DPM measurement occurs when volatile organic carbon (VOC) sorbs onto the particulate matter deposit and filter resulting in a positive sampling artifact. To correct for this, a dynamic blank method with two quartz filters (i.e., primary and secondary) in tandem is used. However, the accuracy of the dynamic blank correction method is dependent on equal sorption of VOC onto each filter. Observed instances of higher VOC on the secondary filter result in underestimated POC measurements and in some cases negative POC.
The work presented in this thesis investigates the sources of VOC interference in particulate matter sampling and possible solutions. Three existing datasets containing information from blank samples and laboratory and field DPM samples were analyzed to look into instances of higher VOC sorption onto the secondary filter. Negative total POC results were limited to blank samples, but negative results for the POC of individual isotherms were observed in blank and DPM samples. A follow-up study looked into the possibility of sampling materials as a source of VOC that preferentially sorbs onto the secondary filter. Blank samples were assembled to test five sampling materials (i.e., two types of sample cassette, cellulose support pads, impactor cassettes, and impactors). In addition, sample storage conditions (i.e., temperature and duration) were tested for their impact on VOC sorption. It was discovered that all of the sample materials tested contributed VOC and, as expected, higher storage temperatures and longer storage durations increase the amount of VOC. Preferential sorption onto the secondary filter was observed in most conditions as well.
A field study explored thermal separation of VOC and POC as a possible alternative to the dynamic blank correction method. Two sets of DPM samples were collected from two locations in an underground stone mine and one set of ambient particulate matter samples was collected from a highly trafficked truck stop. The temperature of 175°C was used for this preliminary investigation. The effectiveness of a temperature separation may depend on sample location. To better understand VOC and POC evolution characteristic, further testing with a wide range of sample mass and composition as well as different temperatures is suggested. It seems unlikely that a correction method using a separation temperature would be more effective than the standard dynamic blank in occupational DPM monitoring. The work presented in this thesis highlights the difficulty in accurately measuring POC.Master of Science
Diesel Particulate matter (DPM) is the solid portion of diesel exhaust and can cause chronic and acute illness. Underground miners can regularly be exposed to high concentrations of DPM over long periods of time, therefore DPM must be monitored. Total Carbon (TC) is the sum of particulate organic and elemental carbon (POC and EC) and is used as the surrogate measurement to represent DPM. The standard method of DPM sample analysis is subject to volatile organic carbon (VOC) interference, therefore a dynamic blank correction is used. However, in some cases, the dynamic blank over- or under-corrects. This thesis presents studies to better understand the source(s) of VOC interference and possible solutions. Three existing datasets containing information from blank samples and laboratory and field DPM samples were investigated for instances of VOC interference resulting in an overcorrection. Such instances were limited to blank and low mass samples. A field study looked into the possibility of sampling materials as a source of VOC that may cause overcorrection when using the dynamic blank method. Blank samples were assembled to test five sampling materials as well as various sample storage conditions. It was discovered that all of the sample materials tested contributed VOC and, as expected, higher storage temperatures and longer storage durations increase the amount of VOC. A second field study explored thermal separation of VOC and POC as a possible alternative to the dynamic blank correction method. Two sets of DPM samples were collected from two locations in an underground stone mine and one set of ambient particulate matter samples was collected from a highly trafficked truck stop. The temperature of 175°C was used for this preliminary investigation. Results indicate that the effectiveness of temperature separation may depend on sample concentration and composition. To better understand VOC and POC evolution characteristic, further testing with a wide range of sample mass and composition, as well as, different temperatures is suggested. The work presented in this thesis highlights the difficulty in accurately measuring POC.
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Ferreira, Ademir de Oliveira. "COMPARTIMENTOS DA MATÉRIA ORGÂNICA DO SOLO COMO INDICADORES DO SEQÜESTRO DE CARBONO EM SISTEMA PLANTIO DIRETO DE LONGA DURAÇÃO." UNIVERSIDADE ESTADUAL DE PONTA GROSSA, 2009. http://tede2.uepg.br/jspui/handle/prefix/2199.
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Previous issue date: 2009-07-13Decrease in soil organic carbon (SOC) content of the surface layer into deeper layers indicates the occurrence of the stratification in the profile due to continuous C addition of crop residues enriching the soil surface layer. The objective of this study was: in Chapter 3 the relationship of stratification (RE) of C of the soil organic matter (SOM) pools can be an indicator of C sequestration in no-tillage soils? In the chapter 4 the tensile strength of aggregates is affected by the C content of Pedosequence of Latosol with medium and clay texture? in Chapter 5 which is the C balance and the amount of crop residue needed to maintain a stable C balance in a Latosol with a medium and clay texture? The experimental design was a completely randomized 2x2x2 factorial with 12 treatments. Treatments consisted of: a) an Oxisol (Red Latosol) with medium and clayey texture, b) two soil sampling periods (T1 and T2) with one year interval between them, and c) two soil sampling depths (0-5 and 5-20 cm). The soil attributes assessed were: the separation of water stable aggregates classes (19-8, 8-4, 4-2, 2-1, 1-0,5 and 05-0,25 mm), particulate organic carbon (POC), total particulate nitrogen (TPN) in the aggregate classes. Also was determined total organic carbon (TOC) and total nitrogen (NT) in the whole sample and in the aggregates sizes classes and tensile strength of aggregates. The relationship of stratification was calculated by dividing the TOC and TN values of 0-5 cm layer by the values of the same attributes of 5-20 cm layer. The C sequestration rate and the stratification ratio changes were calculated by the difference between the T2 values minus T1. The tensile strength was measured in soil aggregates and assessed in 1920 aggregates for each sampling time. Also TOC and NT content were measured in aggregates. The aggregates greater than 8 mm represented more than 70 of the total mass in both the clay and in sandy soil. The relationship of stratification ratio (0-5:5-20 cm) of SOC, TN, POC and TPN soil indicated the improvement of the surface layer. A significant linear relationship between the SR and C sequestration rate in both textural classes showed an increase in C sequestration and was more evident in LV with medium texture. The increase in TOC content resulted in decreased tensile strength (TS) of the aggregates and was more evident in the 0-5 cm layer. The TS showed inverse relationship with the soil density and was higher in the LV medium texture. The rate of sequestration of C was 0.86 for the LV with medium texture and 0.76 Mg ha-1 for the clay texture and to maintain the stable balance of C is required an input of 8.6 Mg ha-1 of crop residues. The results presented confirm the hypothesis of SR to be a sensitive indicator for the rate of carbon sequestration in no-tillage soil. Key-words: Carbon stock, Carbon balance, Carbon sequestration, Soil management systems, particulate organic carbon, particulate nitrogen.
A redução no conteúdo de carbono (C) da camada superficial em direção as camadas mais profundas do solo indica a formação da estratificação no perfil devido à adição contínua de C pelos resíduos orgânicos resultando no enriquecendo a camada superficial do solo. O objetivo deste trabalho foi avaliar os seguintes assuntos: a) a relação de estratificação (RE) de C dos compartimentos da matéria orgânica do solo (MOS) pode ser um indicador do seqüestro de C no sistema plantio direto. b) a resistência tênsil dos gregados pode ser afetada pelo conteúdo de C em Pedossequencia de Latossolo com textura média e argilosa. c) o balanço de C e a quantidade de resíduos culturais necessária para manter o equilíbrio estável de C em um Latossolo com textura média e argilosa. O delineamento experimental foi um fatorial 2x2x2 inteiramente casualizado com 12 tratamentos. Os tratamentos constituíram-se de: a) um Latossolo Vermelho com textura média e argilosa, duas épocas de amostragem do solo (E1 e E2) com um ano de intervalo entre si e duas profundidades de amostragem (0-5 e 5-20 cm). Os atributos avaliados foram: a separação das classes de agregados do tamisamento úmido (19-8, 8-4, 4-2, 2-1, 1-0,5 e 05-0,25 mm), o carbono orgânico particulado (COP), o nitrogênio total particulado (NTP) nas classes de agregado, o C orgânico total (COT) e o nitrogênio total (NT) na amostra integral e nas classes de agregados e a resistência tênsil dos agregados. A relação de estratificação (RE) foi calculada dividindo-se o valor de COT e NT da camada de 0-5 cm pelo valor na camada 5-20 cm. A taxa de seqüestro de C e a variação da relação de estratificação foram calculadas através da diferença (D) entre os valores da E2 menos o da E1. A resistência tênsil (RT) do solo foi avaliada em 1920 agregados de cada época de coleta, determinando-se, também o conteúdo de COT e NT. A classe de agregado > 8 mm representou mais de 70% da massa dos agregados tanto na textura argilosa como na arenosa. Da mesma forma, o conteúdo de COT e NT foram maiores na classe de agregado > do que 4 mm comparado as demais classes nas duas classes texturais. A relação de estratificação 5:5-20 cm) de COT, NT, COP e NTP do solo indicou a melhoria da qualidade do solo da camada superficial. A relação linear e significativa entre o DRE com a taxa de seqüestro de carbono nas duas classes texturais mostrou o aumento no seqüestro de C e foi mais evidente no LV com textura média. O incremento do conteúdo de COT resultou na diminuição da resistência tênsil (RT) dos agregados e foi mais evidente na camada de 0-5 cm. A RT apresentou relação inversa com a densidade do solo e foi superior no LV textura média. A taxa de seqüestro de C foi de 0,86 para o LV textura média e 0,76 Mg ha-1 para o textura argilosa e para manter o equilíbrio estável de C é necessário o aporte de 8,6 Mg ha-1 de resíduos culturais. Os resultados apresentados confirmaram a hipótese da RE ser um indicador sensível para a taxa de seqüestro de carbono no solo em um sistema sob plantio direto consolidado.
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Sabetraftar, Karim, and Karim Sabetraftar@anu edu au. "The hydrological flux of organic carbon at the catchment scale: a case study in the Cotter River catchment, Australia." The Australian National University. Centre for Resource and Environmental Studies, 2005. http://thesis.anu.edu.au./public/adt-ANU20070502.141450.
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Existing terrestrial carbon accounting models have mainly investigated atmosphere-vegetationsoil
stocks and fluxes but have largely ignored the hydrological flux of organic carbon. It is
generally assumed that biomass and soil carbon are the only relevant pools in a landscape
ecosystem. However, recent findings have suggested that significant amounts of organic carbon
can dissolve (dissolved organic carbon or DOC) or particulate (particulate organic carbon or
POC) in water and enter the hydrological flux at the catchment scale. A significant quantity of
total organic carbon (TOC) sequestered through photosynthesis may be exported from the
landscape through the hydrological flux and stored in downstream stocks.¶
This thesis presents a catchment-scale case study investigation into the export of organic carbon
through a river system in comparison with carbon that is produced by vegetation through
photosynthesis. The Cotter River Catchment was selected as the case study. It is a forested
catchment that experienced a major wildfire event in January 2003. The approach is based on an
integration of a number of models. The main input data were time series of in-stream carbon
measurements and remotely sensed vegetation greenness. The application of models to
investigate diffuse chemical substances has dramatically increased in the past few years because
of the significant role of hydrology in controlling ecosystem exchange. The research firstly
discusses the use of a hydrological simulation model (IHACRES) to analyse organic carbon
samples from stream and tributaries in the Cotter River Catchment case study. The IHACRES
rainfall-runoff model and a regionalization method are used to estimate stream-flow for the 75
sub-catchments. The simulated streamflow data were used to calculate organic carbon loads
from concentrations sampled at five locations in the catchment.¶
The gross primary productivity (GPP) of the vegetation cover in the catchment was estimated
using a radiation use efficiency (RUE) model driven by MODIS TERRA data on vegetation
greenness and modeled surface irradiance (RS). The relationship between total organic carbon
discharged in-stream and total carbon uptake by plants was assessed using a cross-correlation
analysis.¶
The IHACRES rainfall-runoff model was successfully calibrated at three gauged sites and
performed well. The results of the calibration procedure were used in the regionalization method
that enabled streamflow to be estimated at ungauged locations including the seven sampling
sites and the 75 sub-catchment areas. The IHACRES modelling approach was found appropriate
for investigating a wide range of issues related to the hydrological export of organic carbon at
the catchment scale. A weekly sampling program was implemented to provide estimates of
TOC, DOC and POC concentrations in the Cotter River Catchment between July 2003 and June
2004. The organic carbon load was estimated using an averaging method.¶
The rate of photosynthesis by vegetation (GPP) was successfully estimated using the radiation
use efficiency model to discern general patterns of vegetation productivity at sub-catchment
scales. This analysis required detailed spatial resolution of the GPP across the entire catchment
area (comprising 75 sub-catchment areas) in addition to the sampling locations. Important
factors that varied at the catchment scale during the sampling period July 2003 June 2004,
particularly the wildfire impacts, were also considered in this assessment.
¶
The results of the hydrologic modelling approach and terrestrial GPP outcome were compared
using cross correlation and regression analysis. This comparison revealed the likely proportion
of catchment GPP that contributes to in-stream hydrological flux of organic carbon. TOC Load
was 0.45% of GPP and 22.5 - 25% of litter layer. As a result of this investigation and giving due
consideration to the uncertainties in the approach, it can be concluded that the hydrological flux
of organic carbon in a forested catchment is a function of gross primary productivity.
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Jiang, Mei. "Mobile Laboratory Measurement of Black Carbon, Particulate Polycyclic Aromatic Hydrocarbons and Other Exhaust Emissions in Mexico City." Thesis, Virginia Tech, 2005. http://hdl.handle.net/10919/41133.
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Black carbon (BC) and polycyclic aromatic hydrocarbons (PAHs) are two atmospheric pollutants produced by motor vehicles using carbonaceous fuels. As a part of the Mexico City Project, measurements of BC, PPAHs and many other gas- and particle-phase emissions were measured in Mexico City using a mobile laboratory during the Mexico City Metropolitan Area field campaign in April 2003 (MCMA-2003). The main goal of this research is to estimate emissions of BC and particulate PAHs (PPAHs) for Mexico Cityâ s vehicle fleet. The emissions of gas-phase pollutants such as carbon monoxide (CO), total nitrogen oxides (NOy) and volatile organic compounds (VOC) are also estimated. The mobile lab has previously been used to chase vehicles and measure their emissions, but analysis has traditionally focused on determining emission factors of individual vehicles associated with specific chasing events. The laboratory continuously samples ambient air from an inlet at the front of the van, and it is always â seeingâ exhaust plumes from the vehicles around it while driving through traffic. We have developed an algorithm that automatically identifies the exhaust plume measurement points, which are then used as the basis for calculation of emission factors. In the nearly 90 hours of on-road sampling during the field campaign, we have identified ~30,000 exhaust measurement points. The large sample size enables us to estimate fleet-average emission factors and thus the emission inventory. Motor vehicles are estimated to emit annually 1,960 tons of BC, 56.2 tons of PPAHs, 1,320,000 tons of CO, 125,000 tons of NOy and 2440 tons of VOCs. The spatial and temporal patterns of BC and PPAHs in different locations with in MCMA are also studied.Master of Science
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Silva, Lênin de Matos. "Avaliação da qualidade ambiental: mercado municipal de São Carlos/SP." Universidade de São Paulo, 2012. http://www.teses.usp.br/teses/disponiveis/18/18138/tde-06062013-160039/.
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O Mercado Municipal de São Carlos é um centro comercial bastante importante, reunindo diversos tipos de lojas e serviços. Um grande número de pessoas frequenta o local diariamente, além de ser o ambiente de trabalho de vários comerciantes. Foi realizado diagnóstico da qualidade do ambiente interno do Mercado Municipal da cidade de São Carlos/SP, através do monitoramento dos seguintes parâmetros: MP10; MP2,5; \'CO IND.2\'; CO; COV; temperatura; umidade relativa e ruído. As coletas de dados foram realizadas durante o ano de 2011. Para todos os parâmetros analisados foram escolhidos 12 pontos amostrais internos e um ponto amostral externo, com exceção do ruído, que teve 9 pontos internos. Os dados amostrais internos de MP10 e de MP2,5 revelaram concentrações médias de 44,55 \'mü\'g/m³ e 31,96 \'mü\'g/m³, respectivamente. As concentrações externas médias foram de 35,60 \'mü\'g/m³ para MP10 e de 25,91 \'mü\'g/m³ para MP2,5. As concentrações médias observadas de material particulado estiveram abaixo dos valores recomendados pela OMS. A razão MP2,5/MP10 esteve acima de 70% indicando predominância de particulado superfino na fração MP10 do material particulado em suspensão. Análises químicas por fluorescência de raios-X foram realizadas no material particulado coletado e os elementos químicos identificados foram: Si, Al, S, Ca, Fe, Ti, Cu, Zn e V. Observou-se que os dados de \'CO IND.2\' ficaram abaixo do limite recomendado pela Resolução ANVISA 09, que é de 800 ppm, os dados internos também foram maiores que os externos. Para o CO e COV, os pontos com maiores concentrações foram os próximos dos acessos ao Mercado pela Rua Episcopal, sendo também maiores os dados internos que o externos. Os dados de temperatura e umidade relativa se mostraram, em geral, fora das faixas de recomendações da Resolução ANVISA 09, o que indica que o ambiente interno do Mercado pode ser desconfortável em relação a esses dois parâmetros. Os níveis internos de ruído observados estiveram acima daqueles recomendados pela Norma Técnica L11.032 (CETESB), que é de 50 dBA. Obteve-se pontos com médias acima de 70 dBA, evidenciando que o local é ruidoso, o que pode acarretar problemas à saúde de seus frequentadores.The Municipal Market of São Carlos city is a very important commercial center, bringing together different types of shops and services. A large number of people attends the local daily, and it is the work environment of several merchants. A diagnostic of the quality of the indoor environment of the Municipal Market of Sao Carlos/SP was conduct, by monitoring the following parameters: PM10, PM2,5; \'CO IND.2\', CO, VOCs, temperature, humidity and noise. The data collections were performed during the year 2011. For all analyzed parameters were chosen 12 sampling indoor points and an outdoor point, with the exception of noise, which had 9 indoor points. The indoor data of PM10 and PM2,5 showed average concentrations of 44.55 \'mü\'g/m³ and 31.96 \'mü\'g/m³, respectively. The outdoor medium concentrations were 35.60 \'mü\'g/m³ for PM10 and 25.91 \'mü\'g/m³ for PM2,5. The average concentrations of particulate matter observed were below the values recommended by WHO. The reason MP2,5/MP10 was above 70%, indicating the predominance of fine particulate matter at the PM10 fraction. Chemical analysis by X-rays fluorescence was performed in the particulate matter collected and the chemicals identified were: Si, Al, S, Ca, Fe, Ti, Cu, Zn and V. It was observed that the \'CO IND.2\' data were below the limit recommended by ANVISA Resolution 09 which is 800 ppm, the indoor data were also higher than outdoor data. For CO and VOCs, the points with the highest concentrations were the ones near the accesses to the Market by the Episcopal Street, and also higher indoor data that the outdoor. The data of temperature and relative humidity proved generally outside the ranges of the recommendations ANVISA Resolution 09, which indicates that the indoor environment of the market may be uncomfortable considering these two parameters. The indoor noise levels were observed above those recommended by the Technical Standard L11.032 (CETESB), which is 50 dBA. There were some points with averages above 70 dBA, showing that the Market can be a noisy environment, which can cause health problems for their users.
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Loh, Ai Ning. "Distribution, Partitioning and Fluxes of Dissolved and Particulate Organic Carbon, Nitrogen and Phosphorus in the Eastern North Pacific and Southern Oceans." W&M ScholarWorks, 1998. https://scholarworks.wm.edu/etd/1539617737.
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Evans, Samantha Lorraine. "Carbon and Nitrogen Stable Isotopic Patterns in South Florida Coastal Ecosystems: Modern and Paleoceanographic Perspectives." FIU Digital Commons, 2008. http://digitalcommons.fiu.edu/etd/189.
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Long term management plans for restoration of natural flow conditions through the Everglades increase the importance of understanding potential nutrient impacts of increased freshwater delivery on coastal biogeochemistry. The present study sought to increase understanding of the coastal marine system of South Florida under modern conditions and through the anthropogenic changes in the last century, on scales ranging from individual nutrient cycle processes to seasonal patterns in organic material (OM) under varying hydrodynamic regime, to century scale analysis of sedimentary records. In all applications, carbon and nitrogen stable isotopic compositions of OM were examined as natural recorders of change and nutrient cycling in the coastal system. High spatial and temporal variability in stable isotopic compositions were observed on all time scales. During a transient phytoplankton bloom, ä15N values suggested nitrogen fixation as a nutrient source supporting enhanced productivity. Seasonally, particulate organic material (POM) from ten sites along the Florida Reef Tract and in Florida Bay demonstrated variable fluctuations dependent on hydrodynamic setting. Three separate intra-annual patterns were observed, yet statistical differences were observed between groupings of Florida Bay and Atlantic Ocean sites. The POM ä15N values ranged on a quarterly basis by 7‰, while ä13C varied by 22‰. From a sediment history perspective, four cores collected from Florida Bay further demonstrated the spatial and temporal variability of the system in isotopic composition of bulk OM over time. Source inputs of OM varied with location, with terrestrial inputs dominating proximal to Everglades freshwater discharge, seagrasses dominating in open estuary cores, and a marine mixture of phytoplankton and seagrass in a core from the boundary zone between Florida Bay and the Gulf of Mexico. Significant shifts in OM geochemistry were observed coincident with anthropogenic events of the 20th century, including railroad and road construction in the Florida Keys and Everglades, and also the extensive drainage changes in Everglades hydrology. The sediment record also preserved evidence of the major hurricanes of the last century, with excursions in geochemical composition coincident with Category 4-5 storms.
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Chu, Housen. "Response and Biophysical Regulation of Carbon Fluxes to Climate Variability and Anomaly in Contrasting Ecosystems." University of Toledo / OhioLINK, 2014. http://rave.ohiolink.edu/etdc/view?acc_num=toledo1418393261.
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Wagner, Hannes [Verfasser]. "Particulate organic matter fluxes and carbon cycling at cold-water coral reefs A three years study at the Tisler Reef, Norway / Hannes Wagner." Bremen : IRC-Library, Information Resource Center der Jacobs University Bremen, 2013. http://d-nb.info/1035269929/34.
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Havens, Julie Ann. "A Stable Isotopic Examination of Particulate Organic Matter During Karenia brevis Blooms on the Central West Florida Shelf: Hints at Nitrogen Sources in Oligotrophic Waters." [Tampa, Fla.] : University of South Florida, 2004. http://purl.fcla.edu/fcla/etd/SFE0000463.
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Hoffmann, Helene [Verfasser], and Ingeborg [Akademischer Betreuer] Levin. "Micro radiocarbon dating of the particulate organic carbon fraction in Alpine glacier ice: method refinement, critical evaluation and dating applications / Helene Margarethe Hoffmann ; Betreuer: Ingeborg Levin." Heidelberg : Universitätsbibliothek Heidelberg, 2016. http://d-nb.info/1180611837/34.
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Niederndorfer, Katharina Róisín [Verfasser]. "Proposal of a practical method to estimate the ecological carrying capacity for finfish mariculture with respect to particulate organic carbon deposition to the seafloor / Katharina Róisín Niederndorfer." Kiel : Universitätsbibliothek Kiel, 2017. http://d-nb.info/1127044249/34.
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Bachmann, Jennifer Eva-Maria [Verfasser], Astrid [Akademischer Betreuer] Gärdes, Astrid [Gutachter] Gärdes, and Dieter [Gutachter] Wolf-Gladrow. "Particulate organic matter : Vector for carbon export, indicator for aquaculture impact and microbial hotspot / Jennifer Eva-Maria Bachmann ; Gutachter: Astrid Gärdes, Dieter Wolf-Gladrow ; Betreuer: Astrid Gärdes." Bremen : Staats- und Universitätsbibliothek Bremen, 2019. http://d-nb.info/1186248653/34.
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Grimm, Christian. "Charge particulaire fluviale : effet sur productivité primaire et implications sur le cycle global du carbone organique." Thesis, Toulouse 3, 2017. http://www.theses.fr/2017TOU30322/document.
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L'apport de matière particulaire fluviale (MPF) aux eaux naturelles joue un rôle essentiel dans le cycle global des éléments et influence le cycle du carbone organique (Corg) de deux façons: 1°, les MPF comprennent une source importante d'éléments nutritifs qui peuvent augmenter la production primaire dans les océans. Par exemple, le flux global de MPF de nutriments tels que Si, P et Fe dépasse son flux dissous par des facteurs de 50, 100 et 350. 2°, l'apport de MPF des continents aux océans est un contrôle majeur de la séquestration du Corg, un processus essentiel dans la réduction du CO2 à long terme par le cycle de Corg. Pour explorer le lien entre l'apport de MPF et la production primaire dans les eaux naturelles, une série d'expériences de croissance a été réalisée impliquant deux producteurs primaires abondants: la cyanobactérie d'eau douce Synechococcus sp. (SYN), et la diatomée marine Thalassiosira weissflogii (TW). Des expériences ont été réalisées en présence et en l'absence de différentes MPF et à différents niveaux nutritifs initiaux. Les résultats démontrent que les MPF augmentent nettement la croissance de la biomasse en fonction de la concentration du MPF. Dans les expériences menées avec la cyanobactérie SYN, la présence de MPF a 1) déclenché une croissance bactérienne dans des conditions pourtant défavorables, 2) augmenté la concentration totale de biomasse et 3) déclenché une croissance bactérienne même après la consommation des nutriments initiaux. L'effet positif des MPF sur la croissance de la diatomée marine TW a été le plus évident pour les expériences n'impliquant pas de nutriments, où les diatomées se sont multipliées linéairement en présence de MPF alors que ces cultures sont mortes en absence des MPF. De plus, des études MEB ont montré un contact physique direct entre les microbes ou les substances organiques excrétées par les microbes et les MPF. Conformément aux travaux issus de la littérature, nous suggérons que les microbes peuvent acquérir des nutriments directement à partir des minéraux, ce qui augmenterait le potentiel des MPF en tant que source de nutriments. Le contact direct suggère aussi une augmentation de l'efficacité de piégeage du Corg par l'augmentation 1) du contenu de Corg absorbé sur les surfaces minérales, 2) de l'agglomération des particules organiques et inorganiques et donc la formation de neige marine ou 3) des vitesses de chute de Corg par "mineral ballasting". La fixation directe des microbes sur les surfaces minérales a également été observée dans les échantillons naturels obtenus au cours d'une étude de terrain sur la côte sud islandaise. Dans l'ensemble, cette étude fournit des preuves expérimentales de l'importance des MPF dans le cycle de Corg grâce à son impact sur la production primaire. En outre, ces travaux rassemblent des preuves que les MPF peuvent faciliter l'inhumation de Corg grâce à la fixation de microbes sur les surfaces ou à la formation des agglomérats minéraux- microbes qui chutent rapidement dans la colonne d´eau. Des études complémentaires ont été effectuées pour évaluer la qualité des compositions isotopiques du carbone, afin de préserver les estimations des taux de séquestration du Corg à travers une période géologique donnée. Les variations du degré de production primaire et du piégeage du Corg au cours des temps géologiques sont conservées dans la signature isotopique du C des carbonates. L'utilisation de ces signatures pour reconstruire les conditions environnementales passées exige cependant que ces signatures soient conservées pour des vastes échelles de temps. Les résultats expérimentaux démontrent que la composition isotopique du C de la calcite évolue continuellement vers l'équilibre isotopique entre les fluides et les minéraux. Cette observation suggère que les compositions isotopiques de C dans la calcite pourraient changer notablement si la calcite était constamment dans un déséquilibre isotopique avec son fluide coexistantThe supply of riverine particulate material (RPM) to natural waters plays a vital role in the global cycle of the elements and is considered to influence the organic carbon cycle in two ways. First, RPM comprise a vast source of nutrients which can increase primary production in the oceans. For example, the global RPM flux of nutrients such as Si, P and Fe exceeds its corresponding dissolved flux by factors of 50, 100 and 350. Second, the supply of RPM to the oceans is a major control of organic matter (Corg) burial, an essential process in the long term CO2 drawdown via the organic pathway. To explore the link between RPM supply and primary production in natural waters, a series of microcosm growth experiments was performed with two common primary producing microbes, the freshwater cyanobacteria Synechococcus sp. and the marine diatom Thalassiosira weissflogii. Experiments were performed in the presence and absence of different RPM at different initial nutrient levels. Results demonstrate that RPM significantly increase bacterial biomass growth as a function of RPM concentration. Notably, in experiments conducted with the freshwater cyanobacteria Synechococcus sp., the presence of RPM 1) triggered bacterial growth in otherwise unfavorable conditions, 2) increased total biomass concentration, and 3) induced steady bacterial growth even after consumption of the initial nutrients. The positive effect of RPM on the growth of the marine diatom Thalassiosira weissflogii was most obvious in nutrient free experiments where cultures grew linearly with time in the presence of RPM, whereas these cultures died in RPM free controls. Furthermore, SEM investigations showed direct physical contact between microbes or microbially excreted organic substances and the particulates. In accord with reports in the literature, we suggest that microbes may acquire nutrients directly from the rock, which would again enhance the potential of RPM as source of limiting nutrients. The direct physical contact also suggests an increase in the burial efficiency of Corg through either 1) increasing Corg content absorbed on mineral surfaces, 2) increasing agglomeration and marine snow formation of organic and inorganic particles or 3) increasing organic matter settling velocities through mineral ballasting. The direct attachment of microbes on mineral surfaces was also observed in natural samples obtained from a field study at the Icelandic South coast. The positive effect of RPM on microbial growth and its effect on Corg burial are complimentary. Agglomeration is a function of suspended particle concentration, organic or inorganic. An elevated biomass concentration induced by the presence of RPM results in a high total suspended matter concentration, thus increasing the particle agglomeration rate. Taken together, this study provides experimental evidence for the importance of RPM in the organic C-cycle through its positive impact on primary production. Furthermore, it compiles evidence that particulates may facilitate organic matter burial through direct attachment of microbes on sediment surfaces or the formation of fast settling mineral/microbe agglomerations. Complimentary studies were performed to assess the quality of carbon isotope compositions to preserve estimates of Corg burial rates over geological time. Variations in the degree of primary production and Corg burial during Earths' history are recorded in the C-isotopic signature of marine carbonates. The use of carbon isotopic signatures in carbonates to reconstruct past environmental conditions, however, requires that these signatures are preserved over vast timescales. Experimental results demonstrate, that the carbon isotopic composition of calcite continuously evolves towards mineral-fluid isotopic equilibrium. This observation suggests that calcite C-isotopic compositions might change noticeably if the calcite were continuously in isotopic disequilibria with its co-existing fluid
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Almeida, Antoine Simões. "Assessment of the inflamatory potential of inhalable organic aerosols present in an urban atmosphere." Master's thesis, Universidade de Aveiro, 2017. http://hdl.handle.net/10773/22707.
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Mestrado em Bioquímica - Bioquímica ClínicaA matéria particulada (sigla inglesa, PM) é definida como uma suspensão de partículas sólidas ou líquidas num gás (i.e., atmosfera), sendo estas tipicamente classificadas de acordo com o seu tamanho: PM10 (diâmetro aerodinâmico < 10μm), PM2.5 (diâmetro aerodinâmico < 2.5μm) e PM1.0 (diâmetro aerodinâmico <1.0μm). Estas partículas podem ser emitidas diretamente para a atmosfera através de fontes antropogénicas ou naturais, ou formadas in situ na atmosfera através de processos físico-químicos. A PM tem impacto relevante não só em processos atmosféricos e climáticos, mas também na saúde humana, onde se destaca o aumento de risco de doenças pulmonares e cardiovasculares, o aumento de suscetibilidade a infeções, e efeitos carcinogénicos e mutagénicos. Particularmente, ao nível pulmonar, os principais efeitos da PM descritos na literatura incluem a indução de stress oxidativo e da inflamação, podendo levar a danos pulmonares. O conhecimento dos efeitos nocivos das PM para a saúde pública resulta fundamentalmente de estudos realizados com as partículas, sendo a contribuição da fração de matéria orgânica solúvel em água (sigla inglesa, WSOM) pouco abordada. Neste sentido, o presente trabalho procura caracterizar a fração WSOM de PM2.5, recolhida durante o período de outono, e avaliar os seus efeitos em macrófagos. A caracterização estrutural, com recurso à técnica de espectroscopia de ressonância magnética nuclear de protão (RMN 1H), mostra que as amostras WSOM recolhidas no período noturno apresentam um maior conteúdo de estruturas aromáticas e oxigenadas do que as amostras recolhidas no período diurno, com estas últimas a apresentarem maior conteúdo em estruturas alifáticas. Adicionalmente, a caracterização das amostras WSOM com recurso à espectroscopia de RMN bidimensional (2D) permitiu identificar diferentes componentes estruturais e determinar possíveis fontes destas estruturas. Os ensaios biológicos de exposição aguda (24h) de macrófagos às amostras WSOM demonstraram que tanto as amostras diurnas como noturnas induzem um aumento da transcrição da enzima destoxificante Hmox, como das moléculas pro-inflamatórias Il1b, Il6 e Nos2. Observou-se também que os extratos apresentam atividade antioxidante in chemico e in vitro. Em ensaios de exposição prolongada (3 semanas) a concentrações fisiologicamente relevantes observou-se um pequeno aumento na transcrição dos genes estudados. No entanto, verificou-se que estes macrófagos apresentavam uma capacidade limitada de resposta a um agente inflamatório como o Lipopolissacarídeo bacteriano (LPS). De uma forma geral, os resultados obtidos indicam que a exposição prolongada a WSOM presente nas partículas atmosféricas pode provocar um ligeiro estado inflamatório a nível pulmonar, limitando, no entanto, a capacidade de resposta dos macrófagos a agentes invasores, o que pode originar um aumento da suscetibilidade a infeções.
Airborne particulate matter (PM), are defined as solid or liquid particles suspended in a gas (i.e., atmosphere), and are typically distributed in three sizeranges: PM10 (coarse PM, aerodynamic diameter < 10μm), PM2.5 (fine PM, aerodynamic diameter < 2.5μm) and PM1.0 (ultrafine PM, aerodynamic diameter < 1.0μm). These particles can be emitted directly into the atmosphere from both anthropogenic and natural sources, or formed in situ in the atmosphere through physico-chemical processes. The PM plays a significant role in diverse atmospheric and climatic processes, as well as on human health by increasing the risk of cardiovascular and pulmonary diseases, the susceptibility to infections, and having carcinogenic and mutagenic effects. Particularly, in the lungs, the main effects of PM described in the literature include the induction of oxidative stress and inflammation, occasionally leading to lung injury. The knowledge of the harmful effects of PM on public health is fundamentally due to studies carried out with particles, being the contribution of the fraction of watersoluble organic matter (WSOM) largely unknown. Therefore, the present work aims to characterize the WSOM fraction of PM2.5, collected during autumn season, and assess its effects on macrophages. The structural characterization of the WSOM from atmospheric particles, by means of proton nuclear magnetic resonance (1H NMR) spectroscopy, showed that samples collected during the night have higher content of aromatic and oxygenated structures than those collected during the day, with the later exhibiting higher content of aliphatic structures. Furthermore, the structural characterization of the WSOM samples by means of two-dimensional (2D) NMR spectroscopy also allowed the identification of different structural components and the tentative assignment of their sources. The biological assays on the effect of an acute exposure (24h) to the WSOM samples showed that both day and night samples induced an increase in the transcription of the detoxifying enzyme Hmox, and the proinflammatory molecules Il1b, Il6 and Nos2. It was also observed that these extracts present antioxidant activity in chemico and in vitro. In the biological assays of prolonged exposure (3 weeks) at physiologically relevant concentrations, it was observed a small increase in the transcription of the studied genes. However, the obtained data show that these macrophages present a limited capacity to respond to an inflammatory agent such as bacterial lipopolysaccharide (LPS). In general, the obtained results show that a prolonged exposure to WSOM present in atmospheric particles can induce or worsen an inflammatory response at the pulmonary level, leading however, to a limited capacity of response of the macrophages to invading agents which could increase the susceptibility to infections.
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Botero, Avila Manuel Fernando. "Fluxo de carbono de zooplâncton e pelotas fecais coletados com armadilhas de sedimentação no sistema de ressurgência de Cabo Frio (RJ)." Niterói, 2017. https://app.uff.br/riuff/handle/1/3354.
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Coordenação de Aperfeiçoamento de Pessoal Nível Superior
Universidade Federal Fluminense. Instituto de Química. Programa de Pós-Graduação em Geociências- Geoquímica, Niterói, RJ
Os oceanos exportam o CO2 atmosférico para o fundo na forma de carbono orgânico particulado (COP) através da sedimentação de partículas planctônicas: detrito, fitoplâncton e pelotas fecais (PF). Em Cabo frio, sudeste da costa Brasileira, os eventos de ressurgência da ACAS ricas em nutrientes possibilitam o aumento na produtividade de comunidades fito e zooplanctônicas, COP e PFs. As PFs exportam carbono (C) para o fundo marinho e seu aporte para o fluxo de COP é variável, afetado pela natureza da rede trófica e a remineralização na coluna de água. O estudo do fluxo de COP é realizado mediante armadilhas de sedimentação que coletam partículas em intervalos pré-programados na parte externa da plataforma continental de Cabo Frio. Um fator de interferência no cálculo de COP é o zooplâncton ou swimmer (SW) que entra ativamente nas armadilhas de sedimentos através da migração vertical, causando uma superestimação no fluxo de partículas. As coletas de SWs e PFs foram realizadas com duas armadilhas de sedimentação em 50 e 100 m de profundidade, equipadas com 13 garrafas coletoras. Os intervalos de coleta foram de 5-7 dias por garrafa durante outono e inverno de 2011 e verão 2012. O material coletado nas garrafas foi passado através de peneiras de 1 mm e 500 μm de malha para separar os SWs. As PFs foram triadas a partir de uma aliquota da amostra peneirada. Os SWs e PFs foram separados, classificados e seu teor de C foi analisado. O fluxo de COP foi entre 0,2 e 4,4 mg C m-2 dia-1 sendo superior durante o verão, épocas de maior produtividade primária, produto de uma maior intrusão da ACAS na camada fótica. Os SWs representaram 63-94 % do C coletado na armadilha e foram constituídos principalmente por copépodos e pterópodos. O fluxo da maioria dos grupos de SWs aumentou no verão, produto de uma maior disponibilidade de alimento e diminuíram com a profundidade. O fluxo de C de PFs representou uma média de 1,5 % do fluxo de COP na maioria dos intervalos o que sugere a predominância de processos de remineralização na coluna d‟água. As variáveis medidas, não explicam os aumentos de PF em dois intervalos do inverno (até 56 % do COP), portanto se verifica uma alta dinâmica física das massas d‟água no ponto de coleta do sistema de ressurgência de Cabo Frio. A alta presença de SWs e o baixo fluxo de PFs descrevem uma área de baixa produtividade e altos processos de remineralização
The oceans export atmospheric CO2 to deep in the form of particulate organic carbon (POC) through the sedimentation of planktonic particles: detritus, phytoplankton and fecal pellets (FP). At Cabo Frio, southeast of Brazil margin coast, upwelling events of rich nutrients waters from South Atlantic Central Water (SACW) allow an increase in productivity of phyto and zooplankton communities, POC and FPs. The FPs can export carbon (C) to depth and their contribution to the POC flux is variable and is affected by the configuration of the food chain and remineralization in the water column. The study of the POC flux its made by sedimentation traps, that collect particles in pre-programmed time intervals on the outer continental shelf of Cabo Frio. The swimmers (SW) are zooplankton that interference on POC flux calculation. The SWs enter actively into the sediment traps through vertical migration, causing an overestimation of particle flux. The sampling of FPs and SWs were performed with two sediment traps with 13 sampler bottles at 50 and 100 m depth. The sampling intervals were 5-7 days per bottle during fall and winter of 2011 and summer of 2012. The collected material in the bottles was sieved with 1 mm and 500 μm sieves to separate SWS. The FPs were picked from an aliquot of the sieved sample. SWs and PFs were separated, sorted and their C content was analyzed. The POC flux oscillated between 0.2 and 4,4 mg C m-2 day-1 being higher during the summer, this is a season with higher primary production due to a higher frequency of intrusions of SAWC in the photic layer. The SWs accounted for 63-94 % of C collected in the trap and were composed mainly of copepods and pteropods. The flux of most groups of SWs increased during summer product of mayor food availability and decrease with depth. The C flux of PFs represents an average of 1.5 % of COP in the most of intervals, which suggests predominance of remineralization processes in the water column. The measured variables did not explain the increase of FPs in two intervals of winter (45-56 % of POC), therefore there is a high physical dynamics of water masses at the collection point in the Cabo Frio upwelling system. The high presence of SWs and low flux of PFs and POC describes an area of with low productivity and high remineralization processes
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Hoare, Ana Maria. "From Source to Sink: An Isotopic Perspective on the Biogeochemical Relationship between the Everglades and Florida Bay." Scholar Commons, 2011. http://scholarcommons.usf.edu/etd/3151.
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Increasing human populations and activities in coastal areas have led to high nutrient loading and estuarine ecosystem decline. Natural hydrological patterns in South Florida have been drastically altered by changes in water management and land use practices. As a result Florida Bay has experienced a series of negative ecosystem effects including hypersalinity events, degradation of water quality, and harmful algal blooms and declines in upper trophic level populations. To remediate ecosystem decline in Florida's coastal ecosystems, the Comprehensive Everglades Restoration Plan proposes to restore a more natural hydrologic flow in the Everglades. It is expected hydrologic restoration efforts will change the amount, sources and ratios of dissolved nutrients (organic and inorganic) delivered to the bay potentially inducing an ecosystem response of changing structure and function in both planktic and benthic habitats.
Identifying biogeochemical linkages between external nutrient inputs from the Everglades and internal cycling processes of Florida Bay is critical to understanding the effects of hydrological restoration and changing nutrient regimes on Florida Bay. A nitrogen (δ15N) and carbon (δ13C ) stable isotopic approach affords an effective means of assessing the fate of varying nutrient sources and delineating the dominant biogeochemical processes governing nutrient cycling in the bay. This study's main goals were to use stable isotopic analyses of C and N in dissolved and particulate materials to determine spatial and seasonal relationships between Everglades nutrient sources and their biological sinks in Florida Bay, examine the biogeochemical relationships among inorganic and organic components of the water column and benthos in Florida Bay, and assess future ecological response to changing nutrient inputs resulting from restoration efforts.
A large east to west gradient from more enriched to more depleted δ15N values was noted in both dissolved nitrogen pools and organic components of the bay. This trend indicates that there are differing nutrient sources and biogeochemical processes influencing the various regions of the bay. Isotopic similarity of the dissolved nitrogen pools from the Everglades and particulate organic matter in the bay points to a strong relationship between both ecosystems. Everglades nutrient inputs delivered to the bay in the wet season directly influence ecological responses in the bay, in some cases increases in algal biomass. Seasonality also influences nitrogen transformations in the dissolved nitrogen pools and the sediments. During dry periods when there is little or no hydrologic flow from the Everglades into the bay, denitrification is a major process affecting nitrogen cycling in the eastern and central regions of the bay. During the wet periods, denitrification becomes suppressed and dissimilatory nitrate reduction (DNRA) is favored. Increased hydrologic flow brings fresh organic matter that fuels DNRA. There was a consistent spatial pattern from more depleted to more enriched δ13C values, onshore to offshore relative to the mainland which indicates strong terrestrial influence on Florida Bay sites along the mangrove boundary with the Everglades. Particulate organic matter exhibited a shift to more enriched δ13C values during the wet season which reflects an increase in algal biomass. A shift to more depleted δ13C values of DOM indicated increased terrestrial influence from the Everglades during the wet season.
The approach undertaken in this study identifies a strong linkage between nutrient inputs from the Everglades and biogeochemical processes in the bay. These findings underscore the need to consider the impact of both allochtonous nutrient inputs and the dominant processes governing cycling in the bay when making management decisions that continue to refine hydrologic restoration plans.
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Karlsson, Emma. "Compositional clues to sources and sinks of terrestrial organic matter transported to the Eurasian Arctic shelf." Doctoral thesis, Stockholms universitet, Institutionen för miljövetenskap och analytisk kemi, 2015. http://urn.kb.se/resolve?urn=urn:nbn:se:su:diva-116876.
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The amount of organic carbon (OC) present in Siberian Arctic permafrost soils is estimated at twice the amount of carbon currently in the atmosphere. The shelf seas of the Arctic Ocean receive large amounts of this terrestrial OC from Eurasian Arctic rivers and from coastal erosion. Degradation of this land-derived material in the sea would result in the production of dissolved carbon dioxide and may then add to the atmospheric carbon dioxide reservoir. Observations from the Siberian Arctic suggest that transfer of carbon from land to the marine environment is accelerating. However, it is not clear how much of the transported OC is degraded and oxidized, nor how much is removed from the active carbon cycle by burial in marine sediment. Using bulk geochemical parameters, total OC, d13C and D14C isotope composition, and specific molecular markers of plant wax lipids and lignin phenols, the abundance and composition of OC was determined in both dissolved and particulate carrier phases: the colloidal OC (COC; part of the dissolved OC), particulate OC (POC), and sedimentary OC (SOC). Statistical modelling was used to quantify the relative contribution of OC sources to these phases. Terrestrial OC is derived from the seasonally thawing top layer of permafrost soil (topsoil OC) and frozen OC derived from beneath the active layer eroded at the coast, commonly identified as yedoma ice complex deposit OC (yedoma ICD-OC). These carbon pools are transported differently in the aquatic conduits. Topsoil OC was found in young DOC and POC, in the river water, and the shelf water column, suggesting long-distance transport of this fraction. The yedoma ICD-OC was found as old particulate OC that settles out rapidly to the underlying sediment and is laterally transported across the shelf, likely dispersed by bottom nepheloid layer transport or via ice rafting. These two modes of OC transport resulted in different degradation states of topsoil OC and yedoma ICD-OC. Terrestrial CuO oxidation derived biomarkers indicated a highly degraded component in the COC. In contrast, the terrestrial component of the SOC was much less degraded. In line with earlier suggestions the mineral component in yedoma ICD functions as weight and surface protection of the associated OC, which led to burial in the sediment, and limited OC degradation. The degradability of the terrestrial OC in shelf sediment was also addressed in direct incubation studies. Molecular markers indicate marine OC (from primary production) was more readily degraded than terrestrial OC. Degradation was also faster in sediment from the East Siberian Sea, where the marine contribution was higher compared to the Laptev Sea. Although terrestrial carbon in the sediment was degraded slower, the terrestrial component also contributed to carbon dioxide formation in the incubations of marine sediment. These results contribute to our understanding of the marine fate of land-derived OC from the Siberian Arctic. The mobilization of topsoil OC is expected to grow in magnitude with climate warming and associated active layer deepening. This translocated topsoil OC component was found to be highly degraded, which suggests degradation during transport and a possible contribution to atmospheric carbon dioxide. Similarly, the yedoma ICD-OC (and or old mineral soil carbon) may become a stronger source with accelerated warming, but slow degradation may limit its impact on active carbon cycling in the Siberian Shelf Seas.At the time of the doctoral defense, the following papers were unpublished and had a status as follows: Paper 3: Manuscript. Paper 4: Manuscript.
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Ribeiro, Ana Renata Louzada. "Distribuição de carbono e nitrogênio orgânicos particulados em duas enseadas do estuário da Lagoa dos Patos- RS." reponame:Repositório Institucional da FURG, 2006. http://repositorio.furg.br/handle/1/3508.
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Dissertação(mestrado) - Universidade Federal do Rio Grande, Programa de Pós-Graduação em Oceanografia Física, Química e Geológica, Instituto de Oceanografia, 2006.Submitted by Cristiane Silva (cristiane_gomides@hotmail.com) on 2013-02-18T14:26:38Z No. of bitstreams: 1 2007_ana_renata.pdf: 1874697 bytes, checksum: bf17d3113d513b65a1b3794a25a72638 (MD5)
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Em estuários, o carbono e o nitrogênio orgânicos particulados (COP e NOP) estão entre os principais constituintes do material em suspensão (MS). O carbono orgânico pode provir de fontes naturais em muitas áreas costeiras, porém tem-se observado processos de eutrofização originados de intensos aportes antrópicos de COP e NOP. Pesquisas relativas à fração orgânica do MS no estuário da Lagoa dos Patos são escassas para o carbono e nitrogênio. Em função de sua importância o presente trabalho estuda este aspecto, sendo parte do grupo temático “Qualidade Ambiental e Biodiversidade”, que se enquadrada no projeto “Uso e Apropriação dos Recursos Costeiros (RECOS)”, do Instituto do Milênio. O presente estudo tem como objetivo avaliar a distribuição de COP e NOP nas enseadas Saco da Mangueira (impactada) e Saco do Arraial (menos impactada), através do desenvolvimento do método de análise elementar CHNS, para avaliar o estado de contaminação orgânica das referidas enseadas e compará-lo com outros ambientes aquáticos. O presente estudo ocorreu de outubro/03 a junho/04, nas duas enseadas, com coletas bimensais da água de superfície em 4 locais de cada uma. As amostras foram filtradas, após os filtros foram secos a 60°C por 24 horas, descarbonatados com vapor de HCl concentrado e novamente secos a 60°C por 24 horas. As amostras foram analisadas para carbono e nitrogênio no equipamento Perkin Elmer CHN/S modelo 2400. Os resultados revelaram variações nas concentrações de COP e NOP na água de superfície, com maiores valores encontrados em dezembro/03 (primavera) e fevereiro/04 (verão). A enseada do Saco do Arraial mostrou características aproximadamente constantes nos níveis de COP (344 a 2354 μg L-1) e NOP (130 a 836 μg L-1), quando comparado com o Saco da Mangueira, sendo que as concentrações mais elevadas estão associadas a contribuições autóctones de produtores primários, destacando-se o fitoplâncton. Entretanto, a enseada do Saco da Mangueira apresentou influência provável de fatores antrópicos nos níveis de COP (193 a 2794 μg L-1) e NOP (72 a 2386 μg L-1) sendo mais expressivos no final da primavera e verão. Em ambas regiões, a participação média do fitoplâncton ao COP menor que 30%, associada aos baixos valores de relação C/N (4–5), confirmam a participação das bactérias juntamente com o fitoplâncton nos níveis de COP e NOP. Os valores mínimos e máximos de COP foram semelhantes entre os dois locais pesquisados, mas a concentração máxima de NOP esteve aproximadamente três vezes maior no Saco da Mangueira, sendo o parâmetro que melhor caracterizou sua eutrofização. Os elementos particulados apresentaram concentrações mínimas e máximas maiores que os valores obtidos nos demais estuários que participaram do Programa RECOS, e semelhantes aos níveis encontrados em outros ambientes aquáticos. Exceção foi encontrada para o valor máximo de NOP no Saco da Mangueira que ficou com concentrações acima dos demais estuários, devido à possibilidade do nitrogênio constituinte do MS ressuspendido ter uma origem não apenas orgânica, mas também inorgânica. Isso se deve ao longo histórico de efeitos humanos no Saco da Mangueira, com elevados aportes de nutrientes e materiais particulados provenientes da área urbana e industrial da cidade de Rio Grande.
In estuaries, the particulate organic carbon and nitrogen (POC and PON) are one of the main constituents of the material in suspension (MS). The organic carbon can come from natural sources in many coastal areas, however it has observed eutrofization processes originated of intense antropic input of POC and PON. Research about the organic fraction of the MS in the estuary of the Patos Lagoon is scarce for carbon and nitrogen. In function of its importance the present work study this subject, being part of the thematic group "Quality Ambient and Biodiversity", that belongs in the project "Use and Appropriation of Recursos Costeiros (RECOS)", of the Institute of the Milênio. The present study has as objective to evaluate the distribution of POC and PON in the Saco da Mangueira (impacted) and Saco do Arraial (less impacted), through the development of the method of elementary analysis CHNS, to evaluate the state of organic contamination of the mentioned embayments and to compare it with other aquatic environments. The present study occurred from outubro/03 to junho/04, in both embayments, with semimonthly collections of surface water in 4 places of each one. The samples were filtered, then the filters were dry at 60°C for 24 hours, exposed to a vapor of HCl and again dried at 60°C for 24 hours. The samples were analyzed for carbon and nitrogen in the equipment Perkin Elmer CHN/S model 2400. The results showed variations in the concentrations of POC and PON in the surface water, with higher values found in dezembro/03 (spring) and fevereiro/04 (summer). The Saco do Arraial showed approximate3ly constant characteristics in the levels of POC (344 the 2354 μg L-1) and PON (130 the 836 μg L-1), when compared with the Saco da Mangueira, being high concentrations associated with autoctones contributions of primary producers, distinguishing the phytoplankton. However, the Saco da Mangueira presented likely influence of antropic factors in the levels of POC (193 the 2794 μg L-1) and PON (72 the 2386 μg L-1) being expressive at the end of the spring and summer. In both regions, the average participation of phytoplankton to the POC lesser that 30%, associated to the low values of relation C/N (4-5), confirm the participation of the bacteria with phytoplankton in the levels of POC and PON. The minimum and maximum values of POC were similar between the two study places, but the maximum concentration of PON was approximately three times bigger in the Saco da Mangueira, being the parameter that better characterized its eutrofization. These particulate elements presented minimum and maximum concentrations greater that values of other estuaries, which participated of Program RECOS, and similar to the levels found in other aquatic environments. Exception was found for the maximum value of PON in the Saco da Mangueira that had concentrations higher than other estuaries, due to the nitrogen constituent of the ressuspended MS to have not only an organic origin, but also inorganic. This should be due to the long historic of human effect in the Saco da Mangueira, with high inputs of nutrients and particulate materials proceeding from urban and industrial areas of the city of Rio Grande.
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Barkle, Gregory Francis. "The fate of carbon and nitrogen from an organic effluent irrigated onto soil : process studies, model development and testing." Lincoln University, 2001. http://hdl.handle.net/10182/1959.
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The fate of the carbon and nitrogen in dairy farm effluent (DFE) applied onto soil was investigated through laboratory experiments and field lysimeter studies. They resulted in the development and testing of a complex carbon (C) and nitrogen (N) simulation model (CaNS-Eff) of the soil-plant-microbial system. To minimise the risk of contamination of surface waters, regulatory authorities in New Zealand promote irrigation onto land as the preferred treatment method for DFE. The allowable annual loading rates for DFE, as defined in statutory regional plans are based on annual N balance calculations, comparing N inputs to outputs from the farming system. Little information is available, however, to assess the effects that these loading rates have on the receiving environment. It is this need, to understand the fate of land-applied DFE and develop a tool to describe the process, that is addressed in this research. The microbially mediated net N mineralisation from DFE takes a central role in the turnover of DFE, as the total N in DFE is dominated by organic N. In a laboratory experiment, where DFE was applied at the standard farm loading rate of 68 kg N ha⁻¹, the net C mineralisation from the DFE was finished 13 days after application and represented 30% of the applied C, with no net N mineralisation being measured by Day 113. The soluble fraction of DFE appeared to have a microbial availability similar to that of glucose. The low and gradually changing respiration rate measured from DFE indicated a semi-continuous substrate supply to the microbial biomass, reflecting the complex nature and broad range of C compounds in DFE. The repeated application of DFE will gradually enhance the mineralisable fraction of the total soil organic N and in the long term increase net N mineralisation. To address the lack of data on the fate of faecal-N in DFE, a ¹⁵N-labelled faecal component of DFE was applied under two different water treatments onto intact soil cores with pasture growing on them. At the end of 255 days, approximately 2% of the applied faecal ¹⁵N had been leached, 11 % was in plant material, 11 % was still as effluent on the surface, and 40% remained in the soil (39% as organic N). Unmeasured gaseous losses and physical losses from the soil surface of the cores supposedly account for the remaining ¹⁵N (approximately 36%). Separate analysis of the total and ammonium nitrogen contents and ¹⁵N enrichments of the DFE and filtered sub-samples (0.5 mm, 0.2µm) showed that the faecal-N fraction was not labelled homogeneously. Due to this heterogeneity, which was exacerbated by the filtration of DFE on the soil surface, it was difficult to calculate the turnover of the total faecal-N fraction based on ¹⁵N results. By making a simplifying assumption about the enrichment of the ¹⁵N in the DFE that infiltrated the soil, the contribution from DFE-N to all plant available N fractions including soil inorganic N was estimated to have been approximately 11 % of the applied DFE-N. An initial two-year study investigating the feasibility of manipulating soil water conditions through controlled drainage to enhance denitrification from irrigated DFE was extended a further two years for this thesis project. The resulting four-year data set provided the opportunity to evaluate the sustainability of DFE application onto land, an extended data set against which to test the adequacy of CaNS-Eff, and to identify the key processes in the fate of DFE irrigated onto soil under field conditions. In the final year of DFE irrigation, 1554 kg N ha⁻¹ of DFE-N was applied onto the lysimeters, with the main removal mechanism being pasture uptake (700 kg N ha⁻¹ yr⁻¹ removed). An average of 193 kg N ha⁻¹ yr⁻¹ was leached, with 80% of this being organic N. The nitrate leaching decreased with increasing soil moisture conditions through controlled drainage. At the high DFE loading rate used, the total soil C and N, pH and the microbial biomass increased at different rates over the four years. The long-term sustainability of the application of DFE can only be maintained when the supply of inorganic N is matched by the demand of the pasture. The complex simulation model (CaNS-Eff) of the soil-plant-microbial system was developed to describe the transport and transformations of C and N components in effluents applied onto the soil. The model addresses the shortcomings in existing models and simulates the transport, adsorption and filtration of both dissolved and particulate components of an effluent. The soil matrix is divided into mobile and immobile flow domains with convective flow of solutes occurring in the mobile fraction only. Diffusion is considered to occur between the micropore and mesopore domains both between and within a soil layer, allowing dissolved material to move into the immobile zone. To select an appropriate sub-model to simulate the water fluxes within CaNS-Eff, the measured drainage volumes and water table heights from the lysimeters were compared to simulated values over four years. Two different modelling approaches were compared, a simpler water balance model, DRAINMOD, and a solution to Richards' equation, SWIM. Both models provided excellent estimation of the total amount of drainage and water table height. The greatest errors in drainage volume were associated with rain events over the summer and autumn, when antecedent soil conditions were driest. When soil water and interlayer fluxes are required at small time steps such as during infiltration under DFE-irrigation, SWIM's more mechanistic approach offered more flexibility and consequently was the sub-model selected to use within CaNS-Eff. Measured bromide leaching from the lysimeters showed that on average 18% of the bromide from an irrigation event bypassed the soil matrix and was leached in the initial drainage event. This bypass mechanism accounted for the high amount of organic N leached under DFE-irrigation onto these soils and a description of this bypass process needed to be included in CaNS-Eff. Between 80 and 90% of the N and C leached from the lysimeters was particulate (> 0.2 µm in size), demonstrating the need to describe transport of particulate material in CaNS-Eff. The filtration behaviour of four soil horizons was measured by characterising the size of C material in a DFE, applying this DFE onto intact soil cores, and collecting and analyzing the resulting leachate using the same size characterisation. After two water flushes, an average of 34% of the applied DFE-C was leached through the top 0-50 mm soil cores, with a corresponding amount of 27% being leached from the 50-150 mm soil cores. Most of the C leaching occurred during the initial DFE application onto the soil. To simulate the transport and leaching of particulate C, a sub-model was developed and parameterised that describes the movement of the effluent in terms of filtering and trapping the C within a soil horizon and then washing it out with subsequent flow events. The microbial availability of the various organic fractions within the soil system are described in CaNS-Eff by availability spectra of multiple first-order decay functions. The simulation of microbial dynamics is based on actual consumption of available C for three microbial biomass populations: heterotrophs, nitrifiers and denitrifiers. The respiration level of a population is controlled by the amount of C that is available to that population. This respiration rate can vary between low level maintenance requirements, when very little substrate is available, and higher levels when excess substrate is available to an actively growing population. The plant component is described as both above and below-ground fractions of a rye grass-clover pasture. The parameter set used in CaNS-Eff to simulate the fate of DFE irrigated onto the conventionally drained lysimeter treatments over three years with a subsequent 10 months non-irrigation period was derived from own laboratory studies, field measurements, experimental literature data and published model studies. As no systematic calibration exercise was undertaken to optimise these parameters, the parameter set should be considered as "initial best estimates" and not as a calibrated data set on which a full validation of CaNS-Eff could be based. Over the 42 months of simulation, the cumulative drainage from CaNS-Eff for the conventionally drained DFE lysimeter was always within the 95% CI of the measured value. On the basis of individual drainage bulking periods, CaNS-Eff was able to explain 92% of the variation in the measured drainage volumes. On an event basis the accuracy of the simulated water filled pore space (WFPS) was better than that of the drainage volume, with an average of 70% of the simulated WFPS values being within the 95% CI for the soil layers investigated, compared to 44% for the drainage volumes. Overall the hydrological component of CaNS-Eff, which is based on the SWIM model, could be considered as satisfactory for the purposes of predicting the soil water status and drainage volume from the conventionally drained lysimeter treatment for this study. The simulated cumulative nitrate leaching of 4.7 g NO₃-N m⁻² over the 42 months of lysimeter operation was in good agreement to the measured amount of 3.0 (± 2.7) g NO₃-N m⁻². Similarly, the total simulated ammonium leaching of 2.7g NH₄- N m⁻² was very close to the measured amount of 2.5 (± 1.35) g NH₄- N m⁻² , however the dynamics were not as close to the measured values as with the nitrate leaching. The simulated amount of organic N leached was approximately double that measured, and most of the difference originated from the simulated de-adsorption of the dissolved fraction of organic N during the l0-month period after the final DFE irrigation. The 305 g C m⁻² of simulated particulate C leached was close to the measured amount of 224 g C m⁻² over the 31 months of simulation. The dissolved C fraction was substantially over-predicted. There was good agreement in the non-adsorbed and particulate fractions of the leached C and N in DFE. However, the isothermic behaviour of the adsorbed pools indicated that a non-reversible component needed to be introduced or that the dynamics of the de-adsorption needed to be improved. Taking into account that the parameters were not calibrated but only "initial best estimates", the agreement in the dynamics and the absolute amounts between the measured and simulated values of leached C and N demonstrated that CaNS-Eff contains an adequate description of the leaching processes following DFE irrigation onto the soil. The simulated pasture N production was in reasonable agreement with the measured data. The simulated dynamics and amounts of microbial biomass in the topsoil layers were in good agreement with the measured data. This is an important result as the soil microbial biomass is the key transformation station for organic materials. Excepting the topsoil layer, the simulated total C and N dynamics were close to the measured values. The model predicted an accumulation of C and N in the topsoil layer as expected, but not measured. Although no measurements were available to compare the dynamics and amounts of the soil NO₃-N and NH₄-N, the simulated values appear realistic for an effluent treatment site and are consistent with measured pasture data. Considering the large amount of total N and C applied onto the lysimeters over the 42 months of operation (4 t ha⁻¹ of N and 42 t ha⁻¹0f C), the various forms of C and N in dissolved and particulate DFE as well as in returned pasture, and that the parameters used in the test have not been calibrated, the simulated values from CaNS-Eff compared satisfactorily to the measured data.
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CHIMENTO, CARLO. "ASSESSMENT OF THE CARBON SEQUESTRATION POTENTIAL IN SOIL AND IN BELOWGROUND BIOMASS OF SIX PERENNIAL BIOMASS CROP." Doctoral thesis, Università Cattolica del Sacro Cuore, 2015. http://hdl.handle.net/10280/6072.
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L'obiettivo della ricerca è stato quello di identificare la coltura bioenergetica con il maggior potenziale di sequestro del carbonio (C); sono state considerate tre colture perenni arboree (pioppo, robinia e salice) e tre colture erbacee perenni (canna comune , miscanto e panico ) al sesto anno dal loro impianto e coltivate nello stesso ambiente.
In primo luogo sono state misurate le variazioni dei tassi del C organico del suolo (COS) per il primo 1 m, mentre per i primi 30 cm di suolo è stato stimato il grado di stabilita del COS valutando sette frazioni di COS che presentano differenti gradi di stabilizzazione; in secondo luogo, sono stati caratterizzati gli apparati radicali delle sei specie per la stessa profondità di suolo, per valutare dove le specie accumulano la biomassa radicale lungo il profilo di suolo. I risultati confermano che l’impianto di colture bioenergetiche perenni su superfici precedentemente dedite a colture annuali gestite convenzionalmente rappresenta una opzione valida per sequestrare C nel soulo. Tuttavia, è stata osservata una diversa capacità di sequestro di C tra specie arboree ed erbacee: le specie arboree hanno dimostrato aumentre il contenuto di COS nel primo strato di suolo ( 0-10 cm di suolo), ma la loro capacità di allocare biomassa radicale negli strati profondi del suolo è limitata; mentre, la specie erbacee allocano un’alta quantità di biomassa radicale negli strati profondi del suolo, ma solo il panico ed il miscanto hanno aumentato il contenuto di C nel primo strato di suolo.The objective of the present research was to identify the bioenergy crop with the greatest carbon sequestration potential among three perennial woody crops (poplar, black locust and willow) and three perennial herbaceous crops (giant reed, miscanthus and switchgrass) at the sixth year from plantation and in the same location. First of all the SOC stock variations for the first 1 m soil depth and the quantification of seven soil C fractions related to SOC stabilization level of the first 30 cm of soil were assessed; secondly, a characterization of the root system and the traits which affect the carbon allocation in soil were considered. The results confirm that the establishment of perennial bioenergy crops in previous arable fields can be a suitable option to sequester carbon (C) belowground. However, a different C sequestration capacity was observed between woody and herbaceous crops: woody species showed the greatest SOC sequestration potential in the first soil layer (0-10 cm of soil) but their ability to allocate root biomass in the deeper soil layers was limited; while, the herbaceous species allocated a high amount of root biomass in the deeper soil layers, but only switchgrass and miscanthus sequester C in the first soil layer.
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Stefani, Faé Giovani. "Integrating Livestock And Winter Annual Forages Into A No-Till Corn Silage System." The Ohio State University, 2008. http://rave.ohiolink.edu/etdc/view?acc_num=osu1228162408.
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Bond, William E. "THE FORESTRY RECLAMATION APPROACH: MEASURING SEDIMENT MASS ACCUMULATION RATES IN RECLAIMED MINE LANDS AND NATURALLY REGENERATED LOGGED FORESTS OF EASTERN KENTUCKY." UKnowledge, 2019. https://uknowledge.uky.edu/ees_etds/75.
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The spread of surface coal mining has resulted in loss of forests in the Appalachian region. The Forestry Reclamation Approach (FRA) was developed to provide guidance for restoring forests on reclaimed mined land. This study hypothesizes that the FRA will result in larger magnitude of sediment accumulation rates in reclaimed mine sites compared to those reclaimed using grassland reclamation. Three sediment cores and six trenches were sampled within four reclaimed mined and three previously logged sites in eastern Kentucky. Samples were processed for radionuclides, grain-size, stable isotopes (δ13C), and POC. LIDAR data were used to identify valley fills, while historical aerial photography was used to identify changes in vegetative cover from 1994 to 2016. Radionuclide dating was used to determine sediment accumulation rates over the previous 100 years. Results from logged sites are inconclusive. δ13C data for all sites fall within the range expected for forested landscapes (C3), and do not show any transitions from grassland to forests. POC data indicates that inventories and fluxes were the same for mined and logged sites. Sediment accumulation rates for reclaimed mined lands show elevated values after the implementation of the FRA, compared to grassland reclamation, thus supporting the hypothesis for previously mined sites.
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Winterfeld, Maria [Verfasser], Gesine [Akademischer Betreuer] Mollenhauer, and Hans-Wolfgang [Akademischer Betreuer] Hubberten. "Biomarker and carbon isotope constraints (δ13C, Δ14C) on sources and cycling of particulate organic matter discharged by large Siberian rivers draining permafrost areas / Maria Winterfeld. Gutachter: Gesine Mollenhauer ; Hans-Wolfgang Hubberten. Betreuer: Gesine Mollenhauer." Bremen : Staats- und Universitätsbibliothek Bremen, 2014. http://d-nb.info/1072303914/34.
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Ravagnani, Elizabethe de Campos. "Dinâmica do nitrogênio e carbono em rios da bacia do Alto Paraíba do Sul, Estado de São Paulo." Universidade de São Paulo, 2015. http://www.teses.usp.br/teses/disponiveis/64/64135/tde-27012016-101247/.
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A Mata Atlântica sofreu e ainda sofre forte pressão antrópica. Atualmente, ocupa no Estado de São Paulo o equivalente a 15% de sua cobertura original. O rio Paraíba do Sul é um dos mais importantes rios da Floresta Atlântica, localizado na região mais desenvolvida do país. Há uma falta de investigações aprofundadas sobre a estruturação e o funcionamento desse rio e de outros rios localizados nessa floresta, como rios de 1ª ordem, que são extremamente importantes, pois conseguem conectar o ambiente terrestre com os rios maiores. Assim, esse trabalho objetivou investigar a distribuição de C e N e outras variáveis físico-químicas nos principais rios localizados na Bacia do Alto Paraíba do Sul: o Rio Paraíba do Sul (RPS) e seus formadores, os rios Paraibuna (RPB) e Paraitinga (RPT), além de investigar a composição química de pequenos rios localizados nas áreas preservadas da Mata Atlântica, comparando-os com os rios de 3ª ordem, e também verificar como a conversão de floresta a pastagem afeta a distribuição de carbono e nitrogênio nesses riachos. Foram realizadas coletas mensais de água durante fevereiro de 2012 a janeiro de 2013, onde foram verificados os valores de pH, condutividade elétrica, oxigênio dissolvido e temperatura, além da determinação das concentrações de nitrogênio dissolvido total, nitrogênio inorgânico dissolvido, nitrogênio orgânico dissolvido, nitrato, amônio, carbono orgânico dissolvido e carbono inorgânico dissolvido. Foi amostrado, também o material particulado em suspensão nos rios de 3ª ordem e o sedimento de fundo em alguns desses rios, onde foram realizadas análises de ?13C e ?15N, conteúdos de C e N e relação C:N. Quase a totalidade das amostras de amônio apresentaram concentrações abaixo do limite de detecção. Os resultados encontrados mostram diferenças estatísticas entre o rio Paraibuna e os rios Paraitinga e Paraíba do Sul, no que se refere aos valores de condutividade elétrica, oxigênio dissolvido, temperatura, nitrato, nitrogênio dissolvido total e carbono inorgânico dissolvido. Esses rios apresentaram valores de nitrato, nitrogênio inorgânico, nitrogênio orgânico, nitrogênio dissolvido total, carbono inorgânico dissolvido, pH, condutividade elétrica, oxigênio dissolvido e temperatura diferentes dos rios de 1ª ordem. Entre rios de floresta e pastagem as variáveis carbono inorgânico dissolvido, condutividade elétrica e temperatura foram diferentes. Esses resultados sugerem que o rio Paraibuna difere-se dos outros rios de 3ª ordem, provavelmente porque 55% da área total de sua bacia é ocupada por floresta, enquanto os rios Paraitinga e Paraíba do Sul apresentam grande parte de suas bacias ocupada por pastagem, 57% e 42%, respectivamente. Entretanto, esses rios não apresentam características de rios extremamente alterados, como é o caso de outros rios do estado de São Paulo, localizados em áreas urbanas ou de cana-de-açúcar, que são muito mais impactantes que pastagens. Tanto os rios de 3ª ordem quanto os rios de 1ª ordem apresentam pastagens subutilizadas e que não recebem fertilizantes ou insumos, fazendo, dessa maneira, com que os rios de pastagem não apresentem características tão diferentes dos rios de florestaThe Atlantic Forest suffered and continues suffering anthropogenic pressure. Nowadays, it occupies 15% of its original coverage in the state of São Paulo. The Paraíba do Sul River is one of the most important rivers of the Atlantic Forest, located in the most developed region of the country. There is a lack of deeper studies of the structure and functioning of this and other rivers of this forest, as first order rivers, that are extremely important, because they can connect terrestrial environment to larger rivers. Therefore, the present study aimed to investigate the distribution of C and N and other physicochemical variables of the main rivers located at the Alto Paraíba do Sul Basin: the Paraíba do Sul River (RPS) an its formers, the Paraibuna (RPB) and Paraitinga (RPT) rivers, also investigating the chemical composition of small rivers located in preserved areas of Atlantic Forest, comparing them with third order rivers, and also focused on the verification of how the conversion of forest to pasture affects the distribution of carbon and nitrogen in these streams. Monthly samples of water were taken from February 2012 to January 2013, for verification of pH, electrical conductivity, dissolved oxygen and temperature values, plus the determination of total dissolved nitrogen, inorganic dissolved nitrogen, organic dissolved nitrogen, nitrate, ammonium, organic dissolved carbon and inorganic dissolved carbon concentrations. Suspended particulate material of the 3rd order rivers and their bottom sediment were sampled, for determination of ?13C, ?15N and C and N content, besides the C:N ratio. The majority of ammonium samples presented concentrations below detection limit. The results show significant statistical differences between the Paraibuna and the Paraitinga and Paraiba do Sul rivers, concerning the values of electrical conductivity, dissolved oxygen, temperature, nitrate, total dissolved nitrogen and inorganic dissolved carbon. These 3rd order rivers presented nitrate, inorganic nitrogen, organic nitrogen, total dissolved nitrogen and dissolved inorganic carbon concentrations, plus pH, electrical conductivity, dissolved oxygen and temperature values different from 1st order rivers. Among the forest and pasture rivers the dissolved inorganic carbon concentration, electrical conductivity and temperature values were different. The results suggest that the Paraibuna River differs from the other two 3rd order rivers, probably because 55% of its total basin area is covered with forest, while the Paraitinga and Paraiba do Sul rivers present a great part of their basin area occupied with pastures, 57% and 42%, respectively. Nevertheless, these rivers did not present characteristics of extremely altered rivers, which is the reality of other rivers of the State of São Paulo, located in urban or sugar cane crop areas, which can cause much more impacts to rivers than pasture. The 3rd and 1st order rivers present sub utilized pasture that do not receive fertilizers, thereby, being the probable cause why pasture rivers are not so different from the forest rivers
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Tomashefski, David J. "An Erodibility Assessment of Central Ohio Cropland Soils." The Ohio State University, 2016. http://rave.ohiolink.edu/etdc/view?acc_num=osu1460994636.
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