Dissertations / Theses on the topic 'Soil CO₂'
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1
Bi, Yuqiang. "Production of Co-Siderophore Complexes by Ligand-Promoted Dissolution." NCSU, 2009. http://www.lib.ncsu.edu/theses/available/etd-05062009-120031/.
Abstract:
Recent research indicates that siderophores, a class of biogenic ligands with known exceptional affinity for Fe(III), can also strongly complex Co(III), an element essential to normal metabolic function of microbes and animals. This study was conducted to examine the siderophore-promoted dissolution rates and mechanisms of Co from model synthetic Co-bearing minerals to elucidate the role of siderophores in biogeochemical processes of Co. Dissolution of heterogenite (CoOOH) and four Co-goethites (Co-FeOOH) with different levels of Co substitution were investigated in the presence of a trihydroxamate siderophore, desferrioxamine B (DFOB), using batch and flow-through experiments, respectively. By measuring the complex and total metal concentrations in dissolution products, dissolution rates via multiple pathways were measured as a function of pH. Results showed that DFOB promoted dissolution of Co from Co-bearing minerals via pH-dependent mechanisms. For heterogenite, ligand-promoted dissolution was the dominant pathway at neutral to alkaline pH, while reductive dissolution became dominant for pH < 6. Cobalt substitution in Co-goethite resulted in increased total dissolution rates of both Co and Fe, but ligand-promoted and reductive Co dissolution pathways were difficult to examine due to the slow dissolution rates. The fast dissolution rate of heterogenite, coupled with the high affinity of Co(III) for DFOB, suggests that siderophore-promoted dissolution of Co(III) oxides is a biogeochemically favorable process. Although the association of Co with Fe oxide mineral may limit the Co dissolution rate, siderophore-promoted Co dissolution may still be an effective enough way to increase Co bioavailability. The results also suggest the possibility of radionuclide 60Co by siderophores from recalcitrant Fe oxide phases, which may be important to the fate and transport of 60Co in contaminated environments.
2
Wytrykush, Laura G. "Effect of soil loading rate on microbial activity during co-composting of diesel-contaminated clay soil." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 2001. http://www.collectionscanada.ca/obj/s4/f2/dsk3/ftp04/MQ57596.pdf.
3
Johnston, Christopher R. "Soil chemical and physical changes resulting from irrigation with coalbed natural gas co-produced water effects of soil amendments and water treatments /." Laramie, Wyo. : University of Wyoming, 2007. http://proquest.umi.com/pqdweb?did=1445033651&sid=10&Fmt=2&clientId=18949&RQT=309&VName=PQD.
4
Khan, Majid Ali. "Impacts of co-formulants on pesticide sorption and leaching through soil." Thesis, University of York, 2016. http://etheses.whiterose.ac.uk/13468/.
Abstract:
A large variety of co-formulants are added to commercial pesticide formulations to enhance their biological effectiveness, but their impacts on the behaviour of active substances are largely unknown due to lack of regulatory measures concerning their use. The overall aim of this research was to investigate the impacts of co-formulants on pesticide sorption and leaching through soil. Leaching and sorption experiments were carried out using technical grade and commercial formulations of four different pesticides at various intervals from application in two soils from the Blackwood and Bishampton associations. The effects of formulation, residence time and soil type on the leaching behaviour of pesticides were all found to be highly statistically significant (p<0.001). Both solubility of the active substance and the type of formulation also influenced the effect of formulation on leaching behaviour of pesticides. The relative difference in mass leached between formulated and technical material of low solubility pesticides was less than that for pesticides with greater water solubility. Greater leaching losses of pesticide were observed from an emulsifiable concentrate (EC) formulation compared to suspension concentrate (SC) formulation for the fungicide azoxystrobin. Results from sorption and desorption experiments on propyzamide in the two soils showed that the batch-equilibrium method is not suitable to study the effect of formulation on pesticide sorption. Rather it is important to use a centrifugation technique under natural moisture conditions to characterise these interactions. The effect of formulation on sorption of propyzamide was highly significant (p<0.001) in sandy loam soil, but there was no effect of formulation in the sandy silt loam soil when characterised by a centrifugation technique. Results suggested that any effect of formulation on pesticide sorption was not sufficient to explain fully the effect of formulation on leaching behaviour. Two-site and three-site sorption models were applied and fitted the sorption phase of the experiment well. However, the models failed to describe the observed desorption behaviour of propyzamide. These results highlight gaps in the existing knowledge about the formulation effects on pesticide sorption and leaching through soil and suggest that these effects should be considered during the risk assessment of environmental fate and behaviour of pesticides.
5
Ferreira, Oscar G. "Supercritical CO₂ extraction of policyclic aromatic hydrocarbons from a contaminated soil." FIU Digital Commons, 1999. http://digitalcommons.fiu.edu/etd/3312.
Abstract:
Polycyclic Aromatic Hydrocarbons (PAHs) that are generated by diverse anthropogenic sources, are classified by the U.S. Environmental Protection Agency (EPA) as Semivolatile Hazardous Compounds. PAHs are pollutants of great concern due to their toxicity and mobility in the environment; they can be found in air, water, and soil media. Supercritical Fluid Extraction (SFE) is currently an alternative technology for the removal of PAHs from solid matrices. Carbon dioxide, water and organic compounds, above their critical temperature and pressure conditions, have been used as supercritical fluids. This bench-scale study evaluates the influence of temperature and use of modifiers on the extraction efficiency of PAHs in a diesel-contaminated soil sample from the Miami International Airport (MIA). Carbon dioxide at supercritical conditions was used as extraction fluid in most of this research. Subcritical water, in vapor and liquid states, was also used in a preliminary testing as extraction fluids. A conceptual design of a supercritical carbon dioxide extraction plant is suggested.
6
Loick, Nadine. "Bioremediation of poly-aromatic hydrocarbon (PAH) contaminated soil by co-composting." Thesis, Bangor University, 2008. https://research.bangor.ac.uk/portal/en/theses/bioremediation-of-polyaromatic-hydrocarbon-pah-contaminated-soil-by-cocomposting(c9621363-f6c1-438a-a899-f23160ce07c3).html.
7
Strömgren, Monika. "Soil-surface CO₂ flux and growth in a boreal Norway spruce stand : effects of soil warming and nutrition /." Uppsala : Swedish Univ. of Agricultural Sciences (Sveriges lantbruksuniv.), 2001. http://epsilon.slu.se/avh/2001/91-576-6304-1.pdf.
8
Henderson, Rachel. "Partitioning soil CO₂ efflux through vertical profiles of manipulated forests in MOFEP /." Connect to Online Resource-OhioLINK, 2007. http://rave.ohiolink.edu/etdc/view?acc%5Fnum=toledo1177701393.
9
Leighton, Rachel. "A combined plant-microbe system for the remediation of co-contaminated soils." Thesis, University of Oxford, 2002. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.270204.
10
Graouer, Bacart Mareen. "Devenir et transfert de polluants émergents issus du secteur de la santé dans les compartiments sol et eau de l’environnement - Influence de la présence d’éléments traces métalliques." Thesis, Reims, 2014. http://www.theses.fr/2014REIMS008.
Abstract:
L'objectif général de ce projet est d'apporter des données pertinentes sur le devenir de produits pharmaceutiques dans l'environnement, en particulier aux interfaces eau/sol, afin de mieux suivre les conséquences de leurs utilisations et de leurs rejets. A long terme, les enjeux concernent la protection de l'environnement et de la santé publique. Ces travaux portent sur la caractérisation des propriétés de rétention de cinq médicaments dans des sols calcaires de la région Champagne-Ardenne afin d'évaluer notamment leur potentiel transfert vers les milieux aquatiques. Différents paramètres ont été identifiés comme ayant une influence sur leur rétention. La rétention de l'enrofloxacine dépend fortement du pH et de la force ionique, celle du diclofénac des teneurs en CaCO3 et en matière organique des sols qui ont un effet antagoniste sur son adsorption, celle de la carbamazépine et du sulfaméthoxazole est faible sur un sol calcaire, et enfin la rétention du iopamidol est négligeable. Par ailleurs, l'influence des cations métalliques, polluants ubiquistes des sols, sur la rétention des médicaments a également été étudiée. Les expériences de co-adsorption ont montré que la présence de cuivre et de zinc influence significativement la rétention de l'enrofloxacine, conduisant à une augmentation des quantités adsorbées sur le sol via la formation d'un complexe ternaire de surface, et met ainsi en évidence l'importance de prendre en compte l'interaction des médicaments avec les métaux pour une meilleure compréhension de leur comportement dans les sols. Toutefois, aucune influence notable de la présence de cuivre sur la rétention des autres produits pharmaceutiques n'a été observéeThe overall objective of this project is to provide a better knowledge of pharmaceuticals fate in the environment, more particularly at water/soil interfaces, in order to follow the consequences of their use and disposal. The long-term issues concern the protection of the environment and public health. This work focuses on the characterization of retention properties of five pharmaceuticals in calcareous soils of the Champagne-Ardenne region in order to evaluate their potential transfer to water compartments. Various parameters having an influence on their retention were identified. The retention of enrofloxacin is highly affected by pH and ionic strength, diclofenac retention by CaCO3 and organic matter contents of soils which have antagonistic effect on its adsorption, the retention of sulfamethoxazole and carbamazepine is low on a calcareous soil, and iopamidol adsorption is negligible. Moreover, the influence of metal cations, ubiquitous pollutants in soils, on pharmaceuticals retention was also studied. Co-adsorption experiments indicated that the presence of copper and zinc modifies significantly enrofloxacin retention, leading to an increase of adsorbed amounts on the soil via the formation of a ternary surface complex, thus highlighting the importance to take into account the interaction between metals and pharmaceuticals for a better understanding of their behavior in soils. However, no noticeable impact of the presence of copper on other pharmaceuticals retention has been noticed
11
Dowey, Una. "Co-contaminant removal of mercury and hydrocarbons from soil using oxidative free radical reactions." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1998. http://www.collectionscanada.ca/obj/s4/f2/dsk2/tape17/PQDD_0007/MQ28932.pdf.
12
Middleton, Amanda Jo. "Nutrient Availability from Poultry Litter Co-Products." Thesis, Virginia Tech, 2015. http://hdl.handle.net/10919/55126.
Abstract:
Phosphorus (P) is a nutrient of concern in the Chesapeake Bay watershed due to nutrient imbalances in areas with confined animal feeding operations. By converting poultry litter to an ash via thermal conversion, nutrients are concentrated and are economical to ship out of nutrient surplus watersheds to nutrient deficient regions, such as the corn-belt. We initiated incubation and field studies on sandy loam soils to test P and potassium (K) availability from poultry litter ash (PLA). Four PLA products, derived from different sources using different combustion techniques, and 2 biochar products were characterized. Poultry litter (PL) co-products were compared to a no-fertilizer control and inorganic P (triple super phosphate; TSP) and inorganic K (muriate of potash; KCl) fertilizer at similar rates. In the incubation study, standard fertilizers (TSP and PL) had the greatest initial availability for P (55.50% TSP; 9.13% PL) and K (97.99% PL), respectively. The PL co-products varied in availabilities based on thermo-conversion system from 1.60- 8.63% for P to 8.14- 88.10% for K. One ash co-product (ASH4) produced similar availabilities to the industry standard fertilizers after 56 days. In conclusion, co-products from combustion thermo-conversion systems were found be superior to gasification and pyrolysis systems when the desire was to produce the most plant available P and K dense PL co-products. In the field studies, yield, Mehlich-I extractable soil nutrients, plant tissue and grain samples, and organic matter content was used to compare treatments. Poultry litter ash co-products were highly variable due to the thermo-conversion system and feedstock of formation. If all ideal combustion criteria are met, then PL co-products are feasible to use as fertilizer sources, but will need to be individually analyzed for nutrient content before making application recommendations. A greater amount of the co-products will have to be applied to meet the same nutrient availability of the standards due to their lower availability. Fresh PL tends to be the better fertilizer due to its added N content, which is lost in thermo-conversion systems and would have to be supplemented with the ash co-products. Biochars tend to be less available than their ash counter parts. More research using the water soluble availabilities instead of the total concentration nutrients of the co-products are needed to be able to identify stronger relationships with standard fertilizers.Master of Science
13
Goswami, Shinjini. "Investigating nutrient co-limitation in northern hardwood forests." Miami University / OhioLINK, 2017. http://rave.ohiolink.edu/etdc/view?acc_num=miami1501414320563565.
14
Sun, Shan. "Patterns, Processes And Models Of Microbial Recovery In A Chronosequence Following Reforestation Of Reclaimed Mine Soils." Diss., Virginia Tech, 2017. http://hdl.handle.net/10919/87754.
Abstract:
Soil microbial communities mediate important ecological processes and play essential roles in biogeochemical cycling. Ecosystem disturbances such as surface mining significantly alter soil microbial communities, which could lead to changes or impairment of ecosystem functions. Reforestation procedures were designed to accelerate the reestablishment of plant community and the recovery of the forest ecosystem after reclamation. However, the microbial recovery during reforestation has not been well studied even though this information is essential for evaluating ecosystem restoration success. In addition, the similar starting conditions of mining sites of different ages facilitate a chronosequence approach for studying decades-long microbial community change, which could help generalize theories about ecosystem succession. In this study, the recovery of microbial communities in a chronosequence of reclaimed mine sites spanning 30 years post reforestation along with unmined reference sites was analyzed using next-generation sequencing to characterize soil-microbial abundance, richness, taxonomic composition, interaction patterns and functional genes.
Generally, microbial succession followed a trajectory along the chronosequence age, with communities becoming more similar to reference sites with increasing age. However, two major branches of soil microbiota, bacteria and fungi, showed some contrasting dynamics during ecosystem recovery, which are likely related to the difference in their growth rates, tolerance to environmental change and relationships with plants. For example, bacterial communities displayed more intra-annual variability and more complex co-occurrence networks than did fungi. A transition from copiotrophs to oligotrophs during succession, suggested by taxonomic composition shifts, indicated that the nutrient availability is one important factor driving microbial succession.
This theory was also supported by metagenomic analysis of the functional genes. For example, the increased abundance of genes involved in virulence, defense and stress response along ages indicated increased competition between microorganisms, which is likely related to a decrease of available nutrients. Metagenomic analysis also revealed that lower relative abundances of methanotrophs and methane monooxygenase at previously-mined sites compared with unmined sites, which supports previous observations that ecological function of methane sink provided by many forest soils has not recovered after 30 years.
Because of the difficulty identifying in situ functional mechanisms that link soil microorganisms with environmental change, modeling can be a valuable tool to infer those relationships of microbial communities. However, the extremely high richness of soil microbial communities can result in extremely complicated models that are difficult to interpret. Furthermore, uncertainty about the coherence of ecological function at high microbial taxonomic levels, grouping operational taxonomic units (OTUs) based on phylogenetic linkages can mask trends and relationships of some important OTUs. To investigate other ways to simplify soil microbiome data for modeling, I used co-occurrence patterns of bacterial OTUs to construct functional groups. The resulting groups performed better at characterizing age-related microbial community dynamics and predicted community structures and environmental factors with lower error.PHD
15
Sindhøj, Erik. "Elevated atmospheric CO₂ in a semi-natural grassland : root dynamics, decomposition and soil C balances /." Uppsala : Swedish Univ. of Agricultural Sciences (Sveriges lantbruksuniv.), 2001. http://epsilon.slu.se/avh/2001/91-576-5797-1.pdf.
16
Watkins, Cody S. "Hydrocarbon and CO2 Emissions from Oil and Gas Production Well Pad Soils Comparative to Background Soil Emissions in Eastern Utah." DigitalCommons@USU, 2017. https://digitalcommons.usu.edu/etd/5666.
Abstract:
Emissions of methane, non-methane hydrocarbons (NMHC), and carbon dioxide (CO2) at 27 natural gas well pads, 11 non-well locations in oil and gas fields, and 7 hydrocarbon-bearing outcrops in eastern Utah between 2013 and 2016 were measured using a dynamic flux chamber (DFC) in effort to answer the following questions: What effect does the development of oil and gas have on the observed air quality (increased ozone, CO2, volatile organic compounds (VOCs), and/or methane emissions) in northeastern Utah? What percentage of these gases is due to natural background emissions, and what percentage is due to oil and gas development in the region? Methane emissions were the focus of this study, but emissions of other compounds were also measured to better understand the sources and characteristics of emissions. Background methane fluxes were all (mg) meter (m)-2 hour (h)-1. Methane emissions from well pad soils were commonly higher closer to the wellhead, though exceptions existed. Methane fluxes from well pad soils ranged from -5.6 to 70,000 mg m-2h-1. Based on analysis of NMHC emissions data, emissions from 68% of the sampled well pad soils were due to leaks of raw natural gas, whereas the remaining emissions were likely from a combination of raw gas leaks, liquid hydrocarbon spills, and/or methanogenic processes. CO2 emissions were higher than methane emissions 92% of the time at well sites, possibly due to CO2 in natural gas, and/or CO2 emitted from bacterial decomposition of soil organic matter and/or fossil hydrocarbons. Total combustible soil gas concentrations were measured at 21 wells. In summer 2015, soil properties were also analyzed to better understand well leakage. Wells categorized as shut-in had the highest average methane fluxes. Measured methane soil emissions were scaled-up for the entire Uinta Basin to estimate the overall emission from well pad soils, and to compare soil emissions with other natural gas-related sources. Producing and shut-in gas wells were estimated to emit 16.1 ± 4.3 and 8.6 ± 3.2 (90% confidence interval) t y-1 (tonne/year) of methane in the Uinta Basin, respectively, which is
17
Mangum, Lauren Heard. "Treatment of Timtek process water by co-composting and aqueous phytoremediation." Master's thesis, Mississippi State : Mississippi State University, 2009. http://library.msstate.edu/etd/show.asp?etd=etd-04022009-101708.
18
Sheedy, Claudia. "Use of immunoaffinity chromatography to remove co-contaminants from soil extracts prior to residue analysis by immunoassay." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 2000. http://www.collectionscanada.ca/obj/s4/f2/dsk1/tape4/PQDD_0035/MQ47362.pdf.
19
Manunta, Paolo. "Modelling strategies of the soil plant atmosphere continuum in water limited environments and elevated atmospheric CO¦2." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 2000. http://www.collectionscanada.ca/obj/s4/f2/dsk1/tape4/PQDD_0010/NQ59998.pdf.
20
Zhang, Fangmei. "DISTRIBUTION OF METABOLIC CHARACTERISTICS AMONG AEROBIC SOIL BACTERIA AND IMPLICATIONS FOR BIOTRANSFORMATION OF ORGANIC AND METALLIC WASTES." Case Western Reserve University School of Graduate Studies / OhioLINK, 2007. http://rave.ohiolink.edu/etdc/view?acc_num=case1164998429.
21
Liu, Jiang Tao. "Development of soil conditioner from co-granulation of waste material with limestone powder in a high shear mixer." Thesis, Queen's University Belfast, 2016. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.707814.
Abstract:
The main aim of this research was to investigate the feasibility of producing an organic fertiliser using waste materials and limestone powder as the raw materials using the process of high shear granulation. The waste materials are anaerobic digest tea waste and sodium-based lignosulfonate. Successful production of improved soil conditioner would reduce the amount of synthetic fertiliser for farm application. It would also provide a sustainable way of managing waste. Two factorial experimental design was used to determine the effect of process and formulation variables on the strength, size distribution, resistance to attrition yield of the granules and nutrient homogeneity of the granules. Additional understanding of the granulation process in the high shear mixer involving binary powder mixes with different physical characteristics was provided.
22
Tang, Li. "The responses of soil microbes to climatic and anthropological factors in the Tibetan grasslands." Thesis, Griffith University, 2021. http://hdl.handle.net/10072/406524.
Abstract:
It is widely known that soil microbes play an important role in biogeochemical cycling, affecting plant growth, and creating soil structure. Faced with the widespread global changes, unravelling the response of soil microbes is essential for understanding soil feedbacks to climate changes. Therefore, there is an increasing interest in studying soil microbial diversity patterns from local to global spatial scales and in investigating changes in soil microbial community diversity and community structure under global changes. However, how soil microbial communities would be altered by natural environmental changes and/or by human induced environmental changes are still not well understood at the regional scale. The Tibetan plateau is known as ‘the third pole’ because of its high elevation of over 4000 m above sea level. Ecosystems in the Tibetan plateau, dominated by alpine grasslands, are fragile and vulnerable to global changes. The increase rate of air temperature is up to three times the global average level. However, we still lack knowledge on responses of soil microbial community to climate gradient and human-induced environmental changes, e.g. climate warming and grazing. This thesis investigated changes in bacterial and fungal community diversity, composition, and co-occurrence along a hydrothermal gradient in the Tibetan plateau grasslands, and the interactive effects of climate changes (warming) and human activities (grazing) on soil microbial functional communities. Specifically, this thesis includes four experiments:
Experiment 1 studied the changes in soil bacterial community along an environmental gradient in the Tibetan plateau. The hypothesis was that alpha diversity of soil bacterial community would increase with higher precipitation and air temperature. We therefore selected sampling sites distributed in main grassland types in the Tibetan plateau. Microbial DNA extracted from soil samples were subjected to the next-generation sequencing to characterize soil bacterial diversity and community. Meanwhile, information of environmental factors 44 was also collected to clarify the driving forces of changes in soil bacterial communities. These factors included mean manual precipitation (MAP), mean manual temperature (MAT), soil moisture (SM), elevation, soil total organic carbon (SOC), total nitrogen (TN), soil carbon: nitrogen ratio (C/N), available phosphorus (AP), soil pH, plant richness, plant aboveground biomass (plant BiomassA), plant belowground biomass (plant BiomassB), NH4+-N, NO3--N, dissolved organic carbon (DOC), soil dissolved organic nitrogen (DON), soil microbial biomass carbon (MBC) and nitrogen (MBN). We used statistical methods including simple correlation, multivariable analysis and structural equation modelling (SEM) to elucidate spatial pattern and the relative importance of biotic and abiotic factors in structuring soil bacterial communities. In the SEM, climate factors were expected to affect soil microbial communities through their influences on plant and soil properties.
Main findings included: in terms of overall bacterial diversity, the swamp meadow with better water conditions had significantly higher diversity than other habitat types, while the alpine desert had the lowest diversity. The overall alpha diversity was significantly correlated with factors that can indicate soil nutrient status including total soil organic carbon, total nitrogen, plant aboveground biomass, nitrate nitrogen (N) and other factors. The effect of environmental factors on the overall bacterial community structure variation was greater than that of spatial factors. The effects of mean annual precipitation (MAP) on soil bacterial alpha diversity were mostly indirect through affecting soil dissolved organic carbon (DOC) and plant richness based on the SEM. Among the environmental factors, the most influential factor for the differences of bacterial community structure was MAP. Unlike the effects on bacterial alpha diversity, MAP had a strong direct effect on soil bacterial community structure. Other factors such as soil DOC and soil pH affected soil bacterial community structure directly without through mediating intermediate variables. By contrast, mean annual 68 temperature (MAT) was not significantly related to soil bacterial diversity or community composition.
Experiment 2 studied soil fungal community of the same soil samples as described in Experiment 1. We hypothesized that there would be a close association between soil fungal community diversity/composition and plant community diversity or composition. The main findings were: Ascomycetes were the most abundant phylum in all samples (84.56%), followed by Basidiomycetes and the Zygomycota. Significantly positive correlation between the relative abundance of Ascomycota and precipitation was found, while the relative abundance of Glomeromycota was not significantly correlated with precipitation. Based on the best-fitting regression model, the most important predictors of fungal species richness were pH and plant species richness. MAP also had substantial effects on soil fungal richness, mostly through its effects on soil pH and plant richness. Environmental factors and geographic distance can independently explain partial changes of fungal community structure with a higher effect by environmental factors. Compared to strong direct effects of soil pH, MAP affected soil fungal community composition by altering soil pH and plant community structure based on structural equation modeling (SEM).
Experiment 3 studied the microbial co-occurrence network along the transect as described in Experiment 1 and 2 by integrating soil bacterial and fungal community data. In this study, Spearman correlation-based network was constructed, and a set of network topological properties were calculated. In addition, the impact factors of network properties were also investigated.
The main findings were: The microbial network size of alpine meadows was greater than that of the alpine steppes. However, the modularity of alpine steppe was higher compared to alpine meadow. In addition, networks of alpine steppe had a larger average path length. Based on these differences in network topological features, soil microbial communities of alpine steppe were considered more stable under environmental interferences. 93 Fungal networks were found to have larger modularity, but smaller inter-nodes connectivity compared with bacterial networks. Although betweenness centrality of bacterial nodes was higher in the alpine meadows, degree centrality was higher in the alpine steppes. The regional meta-network (integrating bacterial and fungal taxa) structure was mostly related to MAP. However, the network topological features of alpine meadows and alpine steppe were driven by different factors. MAP and soil moisture were the significant impact factors for alpine steppe network but not for alpine meadow. The network of alpine meadows was strongly associated with plant factors including biomass and diversity. Besides, fungal networks were not associated with plant community factors, but related to climate factors and soil properties, suggesting that drivers of soil fungal network were different from that of fungal community diversity and structure.
In Experiment 4, we investigated the effects of warming, grazing and their interaction in a factorial warming (+1.2-1.7 oC) and grazing (moderate intensity with ca. 50% vegetation consumption) experiment in a Tibetan alpine meadow on soil microbial communities by studying functional genes involved in soil carbon and nitrogen cycles. We hypothesize that warming would interact antagonistically with grazing to affect soil microbial functional communities. In this study, soil microbial communities were analysed by Geochip and environmental parameters including temperature, soil properties and plant communities were also collected.
The main findings include: microbial functional gene structure and abundances were largely affected by the interactive effect of grazing and warming, rather than the main effect of warming or grazing. Compared to the control, grazing alone significantly increased the functional gene alpha diversity, changed the overall functional community structure, and increased the abundances of C fixation, C degradation, N mineralization and denitrification genes, likely due to the stimulating impact of urine and 118 dung deposition. Warming alone did not change these microbial properties, possibly related to the unchanged soil nutrient status. Despite an increase in soil NO3- concentrations and the deposition of urine and dung, the combined warming and grazing treatment did not change functional gene alpha diversity, community structure, or C/N cycling gene abundances. Our study revealed antagonistic interactions between warming and grazing on microbial functional gene structure and abundances, which remained stable under moderate intensity of grazing in a future warming scenario in the Tibetan alpine meadow.
In sum, this thesis indicated that diversity, composition, and inter-taxa association of soil microbial communities are sensitive to environmental changes in the Tibetan plateau grassland. Climate changes and human activities affected soil microbial communities through direct and indirect pathways. More importantly, the evaluation of microbial-mediated processes in the Tibetan Plateau grasslands should take interactions between climate changes and anthropogenic activities into account.Thesis (PhD Doctorate)
Doctor of Philosophy (PhD)
School of Environment and Sc
Science, Environment, Engineering and Technology
Full Text
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Onojeghuo, Ajoke Ruth Olorunfemi. "Variability and trends of NO₂ and CO over West Africa from space coupled to climate, fire and soil moisture." Thesis, University of Leicester, 2017. http://hdl.handle.net/2381/40872.
Abstract:
Emissions of ozone precursors from biomass burning, soil microbial processes and gas flaring activities over West Africa play major roles in local, regional and global air quality. This thesis investigates the sources, sinks, annual cycles and decadal trends of atmospheric NO2 and CO over West Africa between December 2004 and November 2014 using freely available remotely sensed data and software. Datasets used were soil moisture from ASCAT (MetOp-A/B), CO from IASI (MetOp-A/B), NO2 from OMI, CO from TES (AURA), FRP from SEVIRI (Meteosat) and burned area generated from MODIS (Terra/Aqua) and other sensors. Major contributors to pollution variability considered were climate, biomass burning, gas flaring, soil moisture and atmospheric transport (in the case of CO seasonality). The Savitzky-Golay smoothing algorithm was applied to eliminate false peaks from each time series to improve the identification of seasonality. The trend analysis showed significant decline in NO2 over areas where biomass burning was the main driver of NO2 variability and a significant increase in areas where soil moisture and urban emissions were main drivers. Overall, CO declined inland but trends between December 2008 and November 2014 showed a strong land-ocean difference in linear trends such that inland, CO declined significantly but increased insignificantly offshore. Pixel-wise seasonal relationships between both ozone precursors, biomass burning and soil moisture were assessed using linear regression models. Granger causal tests were carried out to determine the Granger causality of soil moisture and biomass burning on the annual cycles of NO2 and CO. This showed strong soil moisture Granger causality on atmospheric CO in equatorial winter grasslands and NO2 in arid steppe/desert grasslands/shrublands. Burned area showed a strong causality on CO in equatorial winter grasslands. Finally, the dispersion models indicate that beyond biomass burning, gas flaring may contribute to CO transported from the SHA to West Africa in the SHA biomass burning season.
24
Henriksson, Felix, and Joanna Minta. "Bucket-soil interaction for wheel loaders : An application of the Discrete Element Method." Thesis, Linnéuniversitetet, Institutionen för maskinteknik (MT), 2016. http://urn.kb.se/resolve?urn=urn:nbn:se:lnu:diva-53357.
Abstract:
Wheel loaders are fundamental construction equipment to assist handling of bulk material e.g. gravel and stones. During digging operations, it withstands forces that are both large and very complicated to predict. Moreover, it is very expensive to develop prototypes of wheel loader for verification. Consequently, the Discrete Element Method (DEM) was introduced for gravel modeling a couple of years ago to enable prediction of these forces. The gravel model is connected with a Multibody System (MBS) model of the wheel loader, in this thesis a Volvo L180G. The co-simulation of these two systems is a very computer intensive operation and hence, it is important to investigate which parameters that have the largest influence on the simulation results. The aim of this thesis is to investigate the simulation sensitivity with respect to co-simulation communication interval, collision detection interval and gravel normal stiffness.The simulation results are verified by comparison with measurement data from previous tests performed by Volvo CE. The simulations are compared to investigate the relevant parameters. The conclusion of this thesis is that DEM is a method that in a very good way can predict the draft forces during digging operations.
25
Muddimer, Stephen. "Phosphorus (P) partitioning among co-occurring plants : competition for P acquisition across different forms of P and through soil microbes." Thesis, University of Sheffield, 2016. http://etheses.whiterose.ac.uk/16000/.
26
Kerr, Heather Catharine. "Using a water treatment residual and compost co-amendment as a sustainable soil improvement technology to enhance flood holding capacity." Thesis, Durham University, 2019. http://etheses.dur.ac.uk/12983/.
Abstract:
The recycling of clean wastes, such as those from the treatment of drinking water, has gained importance on the environmental agenda due to rising costs of landfill disposal and movement towards a 'zero' waste economy. More than one third of the globe's soils are degraded and as such policies towards determining soil health parameters and reversing destruction of the globe's most valuable non-renewable source are at the forefront of environmental debate. This thesis questions the opportunity for water treatment residual (WTR) to be used as a beneficial material for the co-amendment of soil with compost to improve the soil's flood holding capacity (Kerr et al., 2016), which includes functions such as the water holding capacity, hydraulic conductivity, soil structure and shear strength. Currently, water treatment residual is typically sent to landfill for disposal, but this research shows that the reuse of WTR as a co-amendment is able to improve the flood holding capacity of soils. This research crosses the boundary between geotechnical and geoenvironmental and provides a holistic approach to quantifying a soil from both perspectives. Iron based water treatment residual from Northumbrian Water Ltd was used in both laboratory and field trials to establish the effect of single WTR and a compost and WTR co-amendment on the water holding capacity (the gravimetric water content, volumetric water content, volume change of samples i.e. swelling and shrinkage), and the effect of amendment on the erosional resistance, hydraulic conductivity and shear strength compared to a control soil. A series of four trials were conducted to develop and establish a novel method to determine the water holding capacity, supplemented by standard geotechnical methods to determine the flood holding capacity. The use of x-ray computed tomography has provided accompanying information on the morphology of dried WTR and changes in the internal characteristics of amended soil between a dry and wet state. The amendment application rate ranges from 10 - 50%. Experiments have shown that the single amendment of WTR, compared to a control soil, yields significant increases in the hydraulic conductivity (by up to a factor of 28), increases the shear strength of soils at low testing pressure (25 kPa) by 129%, increases the maximum gravimetric water content by up to 13.7%, and improves swelling by up to 12% (but only at the highest amendment rate, 30%), increases the maximum void ratio when saturated by 11%, and reduces shrinkage by maintaining porosity by 14%. However the application of WTR as a single amendment has implications for the chemical health of the soil as it is highly effective at immobilising phosphorous as and such cannot not effectively be used as a soil amendment. The single application of compost yielded significant improvement in the water holding capacity (improving gravimetric water content by up to 34.7%, increasing the sample volume by up to 83.3%, and increased the void ratio by 8.2%), however this application reduces the hydraulic conductivity by up to 84.5% and the shear strength by 3% compared to the control soil. Co-amendment using compost and WTR (in two forms, air dried 80% solids and wet at 20% solids, as produced from water treatment works) improved the flood holding capacity of soils by retaining the structural improvements of amendment using WTR and the water holding capacity improvements of compost. Compared to the control soil, for co-amended soils the gravimetric water content was improved by up to 25%, the volume increased by up to 51.7%, experienced 13% less shrinkage and an 11.5% increase in maximum void ratio. The hydraulic conductivity was also improved by up to 475%, and shear strength was increased at both low and high testing pressures by to 53.8%. Taking into account these effects of co-amendment on essential soil functions that determines a soil's flood holding capacity (maximum gravimetric water content, volume change, resistance against shrinkage, void ratio (porosity), hydraulic conductivity and shear strength), the economical and environmental sustainability issues, the co-amendment of soil using compost and WTR may provide a solution to both recycling clean waste product and improving the quality of soil.
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Agnello, Ana Carolina. "Potential of alfalfa for use in chemically and biologically assisted phytoremediation of soil co-contaminated with petroleum hydrocarbons and metals." Thesis, Paris Est, 2014. http://www.theses.fr/2014PEST1087/document.
Abstract:
CONTEXTE GENERAL: En raison des activités anthropiques, les sols sont souvent contaminés par des métaux lourds et des hydrocarbures pétroliers. Le nombre important de sites multi-contaminés dans l'environnement met en lumière la nécessité de trouver des solutions adéquates à ces scénarios complexes d'assainissement, qui, de plus, sont rarement étudiés. Parmi les techniques d'assainissement biologique, la phytoremédiation est une technique qui se base sur les propriétés naturelles des plantes pour assainir les sols. L'utilisation conjointe des plantes et des microorganismes pour dépolluer les sols multi-contaminés est une stratégie de traitement en plein essor. Cependant, l'obstacle majeur qui entrave la réussite de tels traitements est la faible biodisponibilité des polluants dans le sol. Par conséquent, la phytoremédiation peut être assistée par des traitements chimiques et/ou biologiques afin de surmonter cette limitation et d'améliorer l'efficacité de l'assainissement. Dans cette étude, l'approche chimique implique l'ajout d'amendements biodégradables. Enfin, la stratégie biologique retenue dans ce travail est la bioaugmentation qui consiste à ajouter dans le sol des bactéries capables d'améliorer l'assainissement des polluants et/ou favoriser la croissance des plantes. PRINCIPAUX OBJECTIFS: a) Étudier le potentiel de la luzerne pour la phytoremédiation des sols multi-contaminés, b) Étudier les effets de l'acide organique de faible poids moléculaire acide citrique et le tensioactif Tween® 80 sur le processus de phytoremédiation et c) Étudier l'effet de la bioaugmentation avec la bactérie Pseudomonas aeruginosa sur le processus de phytoremédiation. METHODES: Détermination des taux de germination et de mortalité, évaluation des paramètres physiologiques des plantes. Quantification de la biomasse végétale, des métaux lourds dans les plantes, hydrocarbures pétroliers totaux (HCT) dans le sol, et indicateurs microbiologiques du sol. Calcul des paramètres de phytoremediation.RESULTATS REMARQUABLES: La luzerne a présenté une faible tolérance aux HCT du sol à 8400 mg kg-1 de matière sèche (MS). Celle-ci qui a été améliorée lorsque les HCT étaient présents à plus faible concentration (3600 mg kg-1 MS). La luzerne a été en mesure de prendre les métaux dans une proportion limitée (<100 mg kg-1 MS), tandis qu'elle a eu un effet positif sur le nombre de microorganismes du sol capables de dégrader les alcanes et sur l'activité de la lipase dans la rhizosphère. En outre, l'application combinée de l'acide citrique et du Tween® 80 a donné lieu à une amélioration plus importante de nombre et de l'activité microbienne dans la rhizosphère. La bioaugmentation avec P. aeruginosa a eu un effet sur l'amélioration de la biomasse de luzerne (augmentation de la biomasse végétale sèche totale de 71%). En outre, les taux les plus élevés d'élimination des HCT (68%, après 90 jours d'expérience) ont été obtenues dans les sols plantés avec la luzerne et bioaugmentées par P. aeruginosa. CONCLUSION GENERALE: La luzerne pourrait tolérer le sol co-contaminé par des métaux lourds et des hydrocarbures pétroliers, ce qui est une caractéristique essentielle en phytoremédiation. La luzerne ne peut cependant pas être considérée comme une espèce capable d'extraire activement les métaux lourds, même en présence d'amendements chimiques ou par bioaugmentation. Néanmoins, l'augmentation du nombre et de l'activité microbienne dans la rhizosphère a confirmé le potentiel de cette plante à être utilisée avec succès dans le traitement des hydrocarbures pétroliers. Ces effets ont été par ailleurs renforcés par l'application conjointe d'acide citrique et de Tween® 80. Enfin, la combinaison de la phytoremédiation et de la bioaugmentation semble une approche prometteuse pour réaliser l'assainissement des hydrocarbures pétroliers, lorsqu'ils sont présents dans des sols multi-contaminésGENERAL BACKGROUND : As a result of anthropogenic activities, soil resources remain contaminated with heavy metals and petroleum hydrocarbons. The high frequency of occurrence of multi-contaminated soils in the environment brings to light the necessity to find remediation solutions adequate in such complex scenarios, which besides have seldom been studied. Phytoremediation is a biologically based remediation technology, which takes advantage of the intrinsic physiological abilities of plants to remediate contaminated media. Plants and their associated microorganisms perform phytoremediation processes (e.g. phytoextraction and rhizodegradation), which can bring about the clean-up of multi-contaminated soils. However, a major constraint which hinders the success of phytotechnologies is low bioavailability of pollutants in soil. As a result, chemically- and biologically-assisted phytoremediation are possible strategies used to overcome this limitation and improve the remediation efficiency. The chemical approach presented in this study involves the addition of biodegradable soil amendments to increase the ability of contaminants to be transferred from a soil compartment to plants and microorganisms. The biological strategy explored herein consists of inoculating contaminated soils with bacteria (bioaugmentation) able to improve remediation of pollutants and/or promote plant features.MAIN OBJECTIVES: a) To investigate the phytoremediation potential of alfalfa (Medicago sativa) in multi-contaminated soils b) To study the effects of the low molecular weight organic acid citric acid and the surfactant Tween® 80 on the phytoremediation process c) To assist phytoremediation with a bioaugmentation approach using Pseudomonas aeruginosa bacteria. METHODOLOGIES: Determination of germination and mortality rates, assessment of plant physiological parameters. Quantification of plant biomass, heavy metals in plants, total petroleum hydrocarbons (TPH) in soil, soil microbiological indicators. Calculation of phytoremediation parameters. REMARKABLE RESULTS : Alfalfa presented low tolerance to TPH contaminated soil at 8400 mg kg-1 soil, which was improved when TPH were present at lower concentration (3600 mg kg-1 soil). Alfalfa was able to take up metals to a limited extent (<100 mg kg-1 dry matter), while had a positive effect in promoting microbial number of alkane degraders and lipase activity in the rhizosphere. Moreover, the combined application of citric acid and Tween® 80 resulted in a greater improvement of these parameters. Bioaugmentation with P. aeruginosa had a promoting effect on alfalfa biomass (71% increase of plant total dry biomass). In addition, the highest TPH removal rates (68%, after 90 days of experiment) were obtained in soils vegetated with alfalfa and bioaugmented with P. aeruginosa.OVERALL CONCLUSION: Alfalfa could tolerate a heavy metal and petroleum hydrocarbon co-contaminated soil (subject to TPH levels), which is an essential characteristic for any plant species to be used in phytoremediation. Alfalfa could not be considered as an actively heavy metal removal species as it was not able to phytoextract significant amounts of heavy metals (still in the presence of soil amendments or bioaugmentation). Nevertheless, the enhancement of microbial number and activity in the rhizosphere encouraged the potential of this plant species to be successfully used in the remediation of petroleum hydrocarbons. These effects were additionally enhanced by the joint application of soil amendments. Finally, the combination of phytoremediation and bioaugmentation seems a promising approach to achieve the remediation of petroleum hydrocarbons, when present in multi-contaminated soils
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KAKEGAWA, Takeshi, Watanabe Fumiko NARA, Kazuho HORIUCHI, Takahiro SAKAI, Tetsuya MATSUNAKA, Mitsugu NISHIMURA, Toshio NAKAMURA, et al. "チベット高原南東部プマユムツォ湖大島から採取した土壌（陸成堆積物）の^<14>C年代測定." 名古屋大学年代測定資料研究センター, 2010. http://hdl.handle.net/2237/14746.
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Nyagatare, Guillaume. "Effect of soil water regime on spatial and temporal distribution of CO₂, CH₄, N₂O and DOC in the soil pore volume : Case study of a calcaric gleysol in the Southwest of Germany /." Stuttgart : Universität Hohenheim, Institut für Bodenkunde und Standortslehre, 2008. http://opac.nebis.ch/cgi-bin/showAbstract.pl?sys=000252296.
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King, Lyle A. "Land application with saline-sodic coalbed natural gas co-produced waters in Wyoming's Powder River Basin impacts to soil and biological properties /." Laramie, Wyo. : University of Wyoming, 2006. http://proquest.umi.com/pqdweb?did=1221694361&sid=3&Fmt=2&clientId=18949&RQT=309&VName=PQD.
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Bloomberg, Simon. "Looking for Permeability: Mass and Heat Flow Assessment Using High Resolution soil CO₂Flux Surveys within the Taupo Volcanic Zone, New Zealand." Thesis, University of Canterbury. Geological Sciences, 2012. http://hdl.handle.net/10092/7436.
Abstract:
Soil CO2 flux (φCO₂) has increasingly become important as a global exploration and monitoring tool in geothermal and volcanic fields. As CO₂ is the second most abundant gas in magma-hydrothermal systems, its study is vital for the location or management of those systems. Often one of the only surface expressions is the diffuse gas flux streaming through the soil zone. This thesis reports the investigations into heat and mass at the Rotokawa geothermal field’s thermal area, and White Island volcano’s crater floor hydrothermal system. Surface measurements were taken at high spatial resolution across the fields in a large sampling campaign during the summers of 2010/2011 and 2011/2012. A large dataset was built up which allowed for greater accuracy during geospatial modelling. The models are 2d pixel plots of the soil gas flux and temperature and are used to estimate values of heat and mass flow for the respective magma-hydrothermal systems. Both field areas have a large anomalous diffuse gas flux through the soil zone and related conductive heat flow anomaly, which indicates relative permeability from the source to the surface in these areas. That the rising fluids from the deep source can be sampled at the surface simply is a powerful tool for the exploration and management of these systems. Rotokawa has a diffuse gas release of over 600 t d⁻¹ and an associated heat flow through soil of 37 MWt while White Island has a diffuse gas release of 116 t d⁻¹ and 19.5 MWt of heat flow through the soil. Translating these values to total heat and mass flow values: Rotokawa has a mass flow 125 kg s⁻¹ and a heat flow of 314 MWt and White Island’s crater floor has a mass flow of 100 kg s⁻¹ and a heat flow of 22 MWt. Fluid flow pathways are mapped from the surface and show arcuate and hot spot spatiality, controlled by fault related permeability and structure. soil gas and temperature surveying elucidates Shallow structures that otherwise may have been hidden from status quo surface mapping. The method used in this study is applicable to both known thermal areas and blind thermal areas by addressing not only the flux but also the nature of the soil gases. Further study of White Island has found more evidence for the existence of seawater infiltration of the crater magma-hydrothermal system.
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Ekumankama, Chinedu. "Effect of heavy metal co-contamination on the biodegradation of polycyclic aromatic hydrocarbons in an urban soil with high organic carbon content." Thesis, Northumbria University, 2015. http://nrl.northumbria.ac.uk/30323/.
Abstract:
Biodegradation is a commonly used approach for the removal of organic contaminants from soil, relying on naturally present microorganisms that utilise the pollutants as an energy source. Often these sites are co-contaminated with heavy metals and the aim of the current research was to investigate how this affects the biodegradation of 16 US EPA priority polycyclic aromatic hydrocarbons (PAHs), both in terms of removal rates and the overall functioning of the soil microbial community. Soil samples were obtained from a Greenfield site in Newcastle upon Tyne. The soil had a high organic content (11.0 %) and also contained elevated lead concentrations as a result of past atmospheric deposition from adjacent industrial activities. PAHs were applied to the soil using a coal tar source dissolved in acetone, giving a total PAH concentration in the spiked soil of 2166 mg kg-1. Individual PAH concentrations ranged from 1.44 mg kg-1 (acenaphthylene) to 325 mg kg-1 (benzo[b]fluoranthene); the benzo[a]pyrene concentration was 255 mg kg-1. The effect of heavy metal co-contaminants on the biodegradation was investigated using separate amendments of cadmium and lead to give respective total concentrations ranging from 133 to 620 mg kg-1 and 340 to 817 mg kg-1. Mercury amendment was used to give an abiotic control. The study was carried out over 40 weeks. For all treatments, the degradation of PAHs was observed to be biphasic. A novel kinetic model was developed to explain this dependence. In the absence of metal amendment, it was found that PAHs comprising two and three benzene rings generally degrade at a faster rate than four- five and six-membered rings. In the presence of metal amendments, overall % biodegradation after 40 weeks is relatively unaffected for two to four-ring PAHs but shows significant impairment for five and six-ring PAHs. Nevertheless, degradation rates generally decrease with increasing metal concentration, as do soil respiration rate, Shannon Diversity Index, and microbial biomass content. Lead appears to exert the greatest inhibitory effect. The novelty of this study arises from the integrated approach to investigating the effect of metal co-contaminants on the biodegradation of all 16 US EPA priority PAHs together with parameters relating to the functioning and diversity of the soil microbial community.
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Raous, Sophie. "Dynamique du nickel et d’autres éléments en traces métalliques (Co, Cr, Cu et Mn) dans des matériaux miniers ultramafiques." Thesis, Vandoeuvre-les-Nancy, INPL, 2011. http://www.theses.fr/2011INPL004N/document.
Abstract:
Une solution pour stabiliser les résidus d’extraction minière de latérites nickélifères est de les végétaliser avec des plantes natives de ces sols ultramafiques. L’objectif de cette thèse était d’étudier la réactivité géochimique des stériles miniers nickélifères des massifs de Niquelândia et Barro Alto (Goiás) dans l’optique de mettre en œuvre ce procédé de revégétalisation.La minéralogie et la réactivité des phases porteuses d’ETM dans les stériles ont été déterminées. L’influence du transport et de la composition de la solution au contact du stérile sur la mobilisation du Ni ont ensuite été étudiées par des expériences en colonne saturée et insaturée. Enfin, la comparaison de la composition de la solution circulant dans les sols naturels ultramafiques avec celle circulant dans des parcelles expérimentales de minerais types a permis d’obtenir une première évaluation de l’adaptabilité des plantes aux stériles.Deux phases majeures sont présentes dans les stériles : un matériau garniéritique, principalement composé de smectites ferrifères riches en Ni échangeable (1230 mg kg-1) ; et un matériau limonitique, principalement composé de goethite, pauvre en nickel mobile, mais riche en Cr(VI) échangeable (980 mg kg-1) complexé en sphère interne à la surface des goethites. Goethite et smectite ont servi de modèles pour affiner la détermination des mécanismes impliqués dans la mobilisation du nickel (modélisation PHREEQC). Outre les réactions de complexation de sphère externe et interne cette étude montre que la dissolution des phases minérales (phyllosilicates, oxydes de fer et de manganèse) et l’adsorption des complexes métal-(citrate/EDTA) jouent un rôle important dans la composition de la solution dans les stérilesA way to ensure physical and chemical stability of mining spoils heaps from nickeliferous laterites is to revegetate them using the native vegetation of the ultramafic soils. The aim of this work was to study the geochemical reactivity of nickeliferous mining spoils of Niquelândia and Barro Alto complexes (Goiás) for the further application of such a revegetation process. Mineralogy and reactivity of TME bearing phases in the spoils were determined. The influence of transport and percolating solution composition on the Ni mobilisation were then studied using saturated and unsaturated column experiments. Finally, the comparison of the composition of solution circulating in natural ultramafic soils with those circulating in experimental plots composed of typical mining ores allowed us to have a first evaluation of the adaptability of natural vegetation to spoils. Two main phases are present in the spoils: a garnieritic spoil, mainly composed of ferruginous smectites enriched in exchangeable Ni (1230 mg kg-1); and a limonitic spoil, mainly composed of goethite with little mobile Ni but very high exchangeable Cr(VI) contents (980 mg kg-1) located as outer sphere complexes at the goethite surface. Synthetic goethite and purified smectite served as model phases to refine the characterisation of main reactive mechanisms implied in Ni mobilisation (PHREEQC modelling). Besides outer (smectite, garnierite) and inner (goethite, limonite) sphere complexation reactions, we showed that the dissolution of mineral phases (phylosilicates, goethite and manganese oxides) and the adsorption of metal-citrate or metal-EDTA complexes do have an important role in the composition of the solution circulating in the spoils
34
Rimmington, Jonathan Neil. "The element composition of soils from archaeological landscapes in Boeotia, Greece : a critical evaluation of element soil analysis in the investigation landscapes co-ordinated with the archaeological survey of Boeotia, Greece." Thesis, Durham University, 1998. http://etheses.dur.ac.uk/1136/.
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Mostoller, Erin Lynn. "Site characteristics and plant invasion light limitation of invasive establishment and impacts of Elaeagnus umbellata on soil nitrogen availability and co-occurring species /." Connect to this title, 2008. http://scholarworks.umass.edu/theses/183/.
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Bordenave, Alexandre. "Traitement in situ des HAPs par co-injection air-vapeur : mécanismes physico-chimiques et optimisation énergétique." Thesis, Bordeaux 3, 2015. http://www.theses.fr/2015BOR30021/document.
Abstract:
La contamination du milieu naturel, notamment des aquifères, par des hydrocarbures lourds de type HAP (Hydrocarbure Aromatique Polycyclique) se révèle être une pollution pérenne très difficile à traiter. La dépollution de ces sous-sols par un traitement in situ efficace et peu coûteux constitue encore aujourd’hui un challenge. Cette étude cible une technique de co-injection air-vapeur en zone saturée comme alternative aux techniques thermiques et chimiques en vigueur pour le traitement de cette catégorie d’hydrocarbures. Une première partie expérimentale introductive estime l’influence d’un simple traitement vapeur sur la libération de HAPs par les matrices de sol au sein de l’aquifère, montrant la nécessité de coupler à ce procédé une technique d’oxydation chimique. Si le front de vapeur permet de mobiliser totalement les composés légers, les concentrations des composés les plus lourds augmentent en phase dissoute (augmentation des fractions molaires des composés résiduels). Réalisées en milieu fermé, dans des conditions de température dictées par l’injection de vapeur (120 ̊C), des expériences en laboratoire ont permis de caractériser et de quantifier les réactions d’oxydation chimique mises en jeu. Les résultats démontrent une efficacité modérée de l’oxydation à moyenne température. Des sous-produits de réaction sont identifiables et quantifiables à compter de plusieurs semaines de réaction. A l’inverse l’étude met en évidence l’absence totale de minéralisation, démontrant que l’ana- lyse du CO2 ne peut renseigner sur l’évaluation du phénomène d’oxydation. Hormis la réactivité par oxydation, les conclusions de l’étude montrent que la technique favorise la sorption irréversible des composés organiques en surface des matrices de sol. Ces phénomènes de sorption sont très marqués en présence d’argile ou de matière organique naturelle dans le milieu et augmentent au cours du temps. La technique HPO se pose donc en traitement de soutien à l’injection de vapeur par oxydation mais surtout par stabilisation de la zone de contamination. Enfin nous nous sommes intéressés aux problématiques liées à l’injection d’eau chaude et de vapeur dans un sous-sol au travers d’expériences sur site. La technique d’injection de vapeur étant financièrement et énergétiquement coûteuse, des solutions techniques ont été proposées, appliquées et modélisées. Il en ressort une comparaison en bilans énergétiques pour différents modes d’injection, permettant de mieux appréhender les véritables besoins d’une telle technique. Parmi les paramètres influents, le rayon d’influence est un paramètre essentiel qui conditionne la distance entre chaque puits pour une efficacité optimale. Les résultats de l’étude démontrent que dans certains scénarios d’injection (injection à grande profondeur) le préchauffage de la zone d’étude par injection d’eau chaude couplé à un pompage en profondeur permettra d’accroître significativement le rayon d’influence et d’améliorer le bilan énergétique du traitement global. Les principaux résultats de la thèse sont comparés aux autres études sur l’injection de vapeur pour dégager les meilleures conditions d’application de cette technique, et mettre en évidence les verrous techniques ayant pu être levés au cours de la thèsePAHs are the largest, ubiquitous and carcinogenic environmental chemical groups. In a context of polluted soil remediation, today it is still a challenge to reach an effective in situ treatment. This study aims to evaluate as an alternative way the potential of a technology combining a thermal process (injection of steam) and a chemical process (co-injection of air) in the saturated zone. A first introductory experimental section considers the influence of a single steam treatment on the release of PAHs from soil matrices within the aquifer. Results prove the necessity of coupling a chemical oxidation technique with this process. If the steam front allows to recover light com- pounds, concentrations of heavier compounds in the dissolved phase are more important after the steam treatment (molar fractions of residual compounds increase). In order to study the fate of PAHs in polluted soils under medium temperature oxidation, numerous experiments in presence of soil spiked matrices were carried out in closed reactors. The catalytic potential of different mineral surfaces was investigated by studying reactivity of different PAHs. Results demonstrate that the efficiency of oxidation remains moderate. They suggest a lack of mineralization and reactions producing partly polycyclic aromatic compounds (PACs) with equivalent molecular weight as the initial contaminants. Along short term experiments (9 days), the major effect of heating is an increase in irreversible sorption of original compounds. Interestingly, this sorption mostly occurs in presence of natural organic matter and oxygen in the gas phase, suggesting a specific reactivity of the natural organic matter. In long term experiments (6 months), new oxygenated PACs were formed and remained fixed on the solid phase. Consequently, air oxidation catalyzed by minerals and natural organic matter may be a new pathway concerning PAH stabilization in soils. The steam injection technique is still considered as a costly technique. In this last part some technical solutions have been proposed, implemented and modelized. The economic aspect of some injection cases are compared, based on the results of a real field application and some general calculations regarding the costs of wells and energy. Among influential parameters, the radius of influence is a key parameter that determines the distance between each well for an optimum efficiency. The results of this study show that in some scenarios of injection (when the injection takes place in a deeper zone), a preheating phase can be an interesting option to reduce the financial costs of the technique. The main results of the thesis are compared with other steam injection studies to identify the best conditions for the technique application
37
Varol, Murat. "Combustion And Co-combustion Of Olive Cake And Coal In A Fluidized Bed." Master's thesis, METU, 2006. http://etd.lib.metu.edu.tr/upload/12607182/index.pdf.
Abstract:
In this study, combustion performances and emission characteristics of olive cake and olive cake+coal mixture are investigated in a bubbling fluidized bed of 102 mm inside diameter and 900 mm height. The average particle sizes of coal and olive cake used in the experiments were 1.57 mm and 1.52 mm, respectively. Flue gas concentrations of O2, CO, SO2, NOx, and total hydrocarbons (CmHn) were measured during combustion experiments. Operational parameters (excess air ratio, secondary air injection) were changed and variation of pollutant concentrations and combustion efficiency with these operational parameters were studied.
The temperature profiles measured along the combustor column was found higher in the freeboard for olive cake than coal due to combustion of hydrocarbons mostly in the freeboard. The location of the maximum temperature in the freeboard shifted to the upper part of the column, as the volatile matter content in the fuel mixture increased.
Combustion efficiencies in the range of 83.6-90.1% were obtained for olive cake with the excess air ratio of 1.12-2.30. The corresponding combustion efficiency for coal was 98.4-99.7% under the same conditions. As the CO and hydrocarbon concentration in the flue gas increased, the combustion efficiency decreased.
Also co-combustion experiments of olive cake and coal for various mixing ratios were carried out. As the amount of olive cake in the fuel mixture increased, SO2 emissions decreased because of the very low sulfur content of olive cake.
In order to increase the combustion efficiency, secondary air was injected into the freeboard which was a good solution to decrease the CO and hydrocarbon emissions, and to increase the combustion efficiency.
For the setup used in this study, the optimum operating conditions with respect to NOx and SO2 emissions were found as 1.35 for excess air ratio, and 30 L/min for secondary air flowrate for the combustion of 75 wt% olive cake and 25 wt% coal mixture. Highest combustion efficiency of 99.8% was obtained with an excess air ratio of 1.7, secondary air flow rate of 40 L/min for the combustion of 25 wt% olive cake and 75 wt% coal mixture.
38
Dwersteg, Daniela [Verfasser]. "Spatial and temporal variability of soil CO2 efflux in a spruce-dominated forest in the Eifel National Park, Germany / Daniela Dwersteg." Bonn : Universitäts- und Landesbibliothek Bonn, 2012. http://d-nb.info/1043911235/34.
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Moraes, Eduardo Aparecido de. "Estudo da influência do teor de acetato de vinila na morfologia e biodegradabilidade de blendas poli(ácido lático)/polietileno-co-acetato de vinila." Universidade de São Paulo, 2017. http://www.teses.usp.br/teses/disponiveis/18/18158/tde-20022018-081224/.
Abstract:
O descarte inadequado de embalagens poliméricas tem gerado uma grande preocupação mundial. O alto consumo, atrelado ao curto tempo de uso dessas embalagens tem ocasionado um grande passivo ambiental. Diferentemente dos usuais polímeros empregados para este propósito, o poli(ácido lático) ou PLA é de fonte renovável e pode ser degradado no meio ambiente por ação de microrganismos como bactérias e fungos. Possui grande potencial para produzir sustentavelmente novos tipos de embalagens que sejam ambientalmente amigáveis. No entanto, para isso é preciso modificar algumas propriedades mecânicas para satisfazer sua aplicação, como a ductilidade e tenacidade. Uma boa alternativa para superar essas limitações é misturá-lo mecanicamente a um segundo polímero, produzindo blendas com propriedades melhoradas. Neste trabalho foram preparadas blendas poliméricas entre o PLA e o copolímero aleatório poli[(etileno)-co-(acetato de vinila)] (EVA), com teores de acetado de vinila (VA) de 65% (EVA65) e 90% (EVA90). As blendas foram preparadas por extrusão em dupla rosca co-rotacional interpenetrante. A morfologia e miscibilidade das blendas PLA/EVA foram estudadas por microscopia eletrônica de varredura (MEV), calorimetria exploratória diferencial (DSC) e análise termodinâmico-mecânica (DMTA). As propriedades mecânicas foram avaliadas por ensaios de tração, flexão em três pontos e resistência ao impacto Izod com entalhe. A influência do teor de VA na biodegradabilidade do PLA foi avaliada por perda de massa e por propriedades mecânicas em tração dos corpos de prova que foram submetidos ao teste de biodegradação em solo e ficaram enterrados por 0, 30, 90, 120 e 150 dias. As curvas DSC e os resultados de DMA mostram que as blendas PLA/EVA90 apresentam uma única temperatura de transição vítrea (Tg), sendo, portanto, miscíveis. Entretanto, as blendas PLA/EVA65 apresentam duas Tg e nítida separação de fases comprovando que são imiscíveis em todas as frações testadas. Mudanças como deslocamento da temperatura de cristalização do PLA são influenciados pelo aumento do teor de EVA nas blendas. Todas as blendas apresentam melhora nos resultados de flexibilidade e deformação na ruptura, destaque para amostra contendo 20% de EVA65 onde a deformação na ruptura foi 350% maior que o PLA puro. A resistência ao impacto da blenda contendo 30% de EVA65 representou um aumento na tenacidade aproximadamente 2400% em relação ao valor obtido pelo PLA puro. A taxa de biodegradação do PLA foi reduzida com o aumento do teor de EVA nas blendas. Blendas com EVA90 obtiveram maiores perdas de massa que as equivalentes contendo EVA65, revelando também a influência da miscibilidade na taxa de biodegradação do PLA. No entanto, ao final de 180 dias todos os corpos de provas sofreram variação negativa da massa, ou seja, foram biodegradados no solo.The inadequate disposal of packaging materials has led to a major worldwide concern. The high consumption, together with the short usage time of packaging materials, has created a serious environmental issue. Unlike conventional polymers, poly(lactic acid) or PLA comes from a renewable source and can be degraded by microorganisms (e.g., bacteria and fungi) in the environment. PLA has a great potential for the sustainable development of environmentally friendly materials intended for packaging applications. To do so, however, some of its mechanical properties (e.g., ductility and toughness) must be modified to meet the technical requirement for such applications. A feasible alternative of overcoming these limitations is mechanically blending PLA with a second polymer, producing blends featuring improved properties. In this study, we prepared polymer blends by mixing PLA and the random copolymer poly[(ethylene)-co-(vinyl acetate)] (EVA) comprising vinyl acetate (VA) contents of 65% (EVA65) and 90% (EVA90). The blends were prepared through interpenetrating co-rotating twin screw extrusion. PLA/EVA blend morphology and miscibility were investigated through scanning electron microscopy (SEM), differential scanning calorimetry (DSC), and dynamic thermomechanical analysis (DMTA). Mechanical properties were determined through tensile, three-point bending, and notched Izod impact strength tests. The influence of VA content on PLA biodegradability was assessed by weight loss measurements as well as tensile tests in specimens submitted to biodegradation in soil, wherein they remained covered for 0, 30, 90, 120, and 150 days. DSC curves and DMTA data showed that the PLA/EVA90 blends presented a single glass transition temperature (Tg), indicating miscibility. On the other hand, the PLA/EVA65 blends presented two Tg as well as marked phase separation, corroborating the immiscibility of all tested fractions. Shifts on the crystallization temperature of PLA are influenced by increased EVA contents in the blends. All blends showed improved flexibility and deformation at break, particularly that comprising 20% EVA65, which presented an elongation at break 350% higher than pristine PLA. The impact strength of the blend comprising 30% EVA65 evidenced a ca. 2400% increase in toughness in comparison with pure PLA. PLA biodegradation rate was reduced by increased EVA contents. EVA90-containing blends displayed greater weight losses than their EVA65-containing counterparts, also revealing the influence of miscibility on PLA biodegradation rate. Nevertheless, after 180 days, all specimens presented weight loss, that is, were biodegraded in soil.
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Antonio, Leonardo Machado. "Análise da interação solo-estrutura aplicada a riser rígido em catenária através da formulação co-rotacional." [s.n.], 2011. http://repositorio.unicamp.br/jspui/handle/REPOSIP/265171.
Abstract:
Orientador: Renato PavanelloDissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Mecânica
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Resumo: A explotação de petróleo em ambientes off-shore possui inúmeras dificuldades, dentre as quais lâminas d'águas cada vez mais profundas. Neste contexto, as linhas submarinas são componentes de grande importância nesta atividade, pois estabelecem a comunicação entre as unidades de produção e os equipamentos submarinos. Este trabalho estuda a interação solo-estrutura de risers rígidos em catenária utilizando a formulação co-rotacional através de abordagens estática e dinâmica. A abordagem estática trata do equílibrio estático de estruturas não-lineares, no qual utiliza-se a estratégia de controle por carregamento;enquanto a abordagem dinâmica utiliza a discretização temporal de Newmark para resolução do equílibrio dinâmico de estruturas não-lineares. Este estudo mostra a implementação de modelos com um e dois parâmetros baseados das hipóteses de Winkler, Filonenko-Borodich e Pasternak no contexto interação da estrutura do riser com o leito marinho
Abstract: The petroleum explotation on off-shore enviorments has differents dificulties, for example deeper water deths. In this context, the marine pipes are components of extreme importance, since they are the comunication between the production units and the subsea equipaments. This work studies the soil-structure interaction of steel cathenary risers using corotational formulation within static and dynamic approaches of structural calculation. The static approach focus on the non-linear static equilibrium of structures using the load control strategy. On the other side, the dynamic approach uses the Newmark time discretization to solve the non-linear dynamic equilibrium equation. This study shows the implementation of foundation with one and two parameter based on hipotheses of Winkler, Filonenko-Borodich and Pasternak in the riser structure and soil interaction context
Mestrado
Mecanica dos Sólidos e Projeto Mecanico
Mestre em Engenharia Mecânica
41
Hellebrandt, Aniko. "The potential of biodegradation on 1, 1, 1-trichloro-2, 2-bis (p-chlorophenyl) ethane, based upon co-metabolism of indigenous bacteria." Thesis, Mälardalens högskola, Akademin för hållbar samhälls- och teknikutveckling, 2010. http://urn.kb.se/resolve?urn=urn:nbn:se:mdh:diva-10339.
Abstract:
The purpose of this project is to evaluate the potential of a bioreactor system to degrade DDT based upon co-metabolism of indigenous bacteria. The study was performed with soil samples spiked with four different concentrations of DDT. The prepared sludge was circulated at a steady rate of revolution per minute in bioreactors with added M8 solution, cabbage leaf extract and molasses. The experiment was carried out for 7 days and chemical analysis and toxicity testing was accomplished at the beginning and the end of the experiment. The chemical analysis was essential to support the conclusions of the ecotoxicology tests. Ecotoxicology test was performed for the assessment of the toxicity (in terms of bioavailable measures) of the sludge samples, and was carried out with the Ostracodtoxkit sediment toxicity test, with the freshwater benthic crustacean test species Heterocypris incongruens. As part of the project the potential of the bioremediation method phytoremediation have been studied. Brassica Juncea seeds have been cultivated in the soil spiked with four different concentrations of DDT for one month, under stable circumstances. Growth of the plants was measured at the end of the experiment, and a chemical analysis was carried out. A thorough literature review was carried out for both the bioreactor and the phytoremediation experiments in order to obtain information about methods and theoretical background. The ecotoxicology tests and the chemical analysis showed increased p,p’- DDT concentrations in the bioreactors I. and II. at the end of the 7 day experiment, the reasons of which are not known, and require further studies.-
42
Medeiros, Sergio Ricardo Rodrigues de. "Utilização da técnica de co-krigagem com inclinação máxima e altitude do terreno no delineamento de zonas de manejo: granulometria do solo e disponibilidade hídrica." Universidade de São Paulo, 2012. http://www.teses.usp.br/teses/disponiveis/11/11143/tde-10072012-091219/.
Abstract:
No Brasil pouco se estuda sobre as estratégias de amostragem em áreas com mais de um tipo de solo e várias feições de paisagem, estratégias estas, importantes para mapear a variabilidade espacial dos atributos físicos: frações granulométricas, como também a correlação destas com os parâmetros geomorfológicos: altitude e inclinação máxima da área amostrada da extensão multivariada da krigagem, a cokrigagem. Essa extensão multivariada permite a associação de duas variáveis dependentes gerarem novas informações correlacionadas através do modelo de variância cruzada. O objetivo deste trabalho foi avaliar a correlação espacial entre a distribuição da fração granulométrica com os parâmetros de altitude e a inclinação máxima através de uma densidade amostral agregada (100x100 e 50x50m) com dois níveis de densidade amostral, 20x20 e 40x40m. O estudo se deu numa área de 180 ha, onde se coletou frações de solo numa grade amostral agregada, ou seja, um arranjo amostral 100x100m e três sub-grades de 50x50m distribuídas aleatoriamente na área. Foi realizada análise estatística descritiva dos dados processados no laboratório e a análise espacial através de modelos de variância. De posse dos modelos ajustados na análise dos variogramas, realizou a interpolação pela krigagem para as frações granulométricas e através dos variogramas cruzados pela cokrigagem, as correlações dessas frações com os dados, obtidos pelo modelo digital de elevação, da altitude e a inclinação máxima do terreno da área e comparada, através dos mapas, essas mesmas correlações em densidades amostrais diferentes. A partir dos modelos de mapas gerados, chegou aos seguintes resultados: houve uma moderada variabilidade das frações granulométricas e uma moderada dependência espacial. De acordo com os parâmetros da variância cruzada a distribuição espacial da fração areia correlacionada com a altitude e com a inclinação máxima não diferenciou significativamente em relação aos níveis de densidade amostral 20x20m e 40x40m, praticamente não houve correlação entre a fração areia e a altitude, pois não apresentou um padrão definido de distribuição espacial. Pode-se concluir que a declividade influenciou na distribuição dos atributos físicos do solo. Como também foi avaliada a disponibilidade hídrica na área do pivô da Fazenda, foi constatada a forte correlação do atributo argila+silte com a capacidade de água disponível (CAD), enfatizando a dependência da disponibilidade hídrica em relação aos atributos físicos do solo.In Brazil, few studied are related about soil sampling strategies in areas with more than one type soil and various features of the landscape, these strategies are important to map the spatial variability of physical attributes: size fractions, as well as the correlation of these with geomorphologic parameters: altitude and maximum slope of the sampled area of the multivariate extension of kriging, cokriging. This extension allows multivariate combination of two dependent variables to generate new information correlated with the model cross variance. The objective of this study was to evaluate the spatial correlation between the distribution of particle size fraction with the parameters of altitude and terrain slope through a maximum aggregate sample density (100x100 and 50x50m) with two levels of sample density, 20x20 and 40x40m. The study was an area of 180 ha, where fractions of collected soil at a sampling grid aggregate, ie an arrangement 100x100m sample and three sub-grids 50x50m randomly distributed in the area. We performed a descriptive statistical analysis of data processed in the laboratory and spatial analysis through models of variance. In possession of the adjusted models in the analysis of variogram for kriging interpolation performed for the fractions and through the variogram crossed by cokriging, the correlations of these fractions with the data obtained by digital elevation model, altitude and the maximum slope of the land area and compared, through maps, these same correlations in different sampling densities. From the models generated maps, it was reached the following results: there was a moderate variability in size fractions and a moderate spatial dependence. In accordance with parameters of cross (semi)variance the spatial distribution of the sand fraction correlated with altitude and the maximum slope did not differ significantly from the levels of sample density 20x20m and 40x40m, virtually no correlation between the sand fraction and altitude because it did not show a definite pattern of spatial distribution. It can be concluded that the slope influenced the distribution of soil physical attributes studieds. It was also quantified the water availability in the area under the center pivot equipment, it was found a strong correlation of the attribute clay + silt with TAW (total available water), emphasizing the dependence on water availability in relation to soil physical properties.
43
Cai, Tiebo. "Analysis of the net ecosystem exchange of CO₂ in a 56-year-old coastal Douglas-fir stand : its relation to temperature, soil moisture and photosynthetically active radiation." Thesis, University of British Columbia, 2007. http://hdl.handle.net/2429/30753.
Abstract:
The primary goal of this thesis was to investigate the relationship of canopy
photosynthesis (P) to photosynthetically active radiation (PAR) in a 56-year-old coastal
Douglas-fir stand (DF49) located on Vancouver Island. Canopy P was calculated as
daytime NEP + daytime R[sub e], where NEP and R[sub e] are net ecosystem production of CO[sub 2] and
ecosystem respiration, respectively. Half-hourly values of NEP were obtained using an
EC (eddy covariance) system consisting of a 3-D sonic anemometer-thermometer and a
closed-path infrared gas (CO[sub 2]/H[sub2]O) analyzer, and daytime R[sub e] was inferred by obtaining
the intercept of the relationship between half-hourly values of NEP and PAR. Daytime R[sub e]
thus obtained was approximately 71-75% of that calculated by applying the
logarithmically-transformed relationship between nighttime NEE (-NEP) and soil
temperature (T[sub s]) to daytime half hours. Values of R[sub 10] (the rate of R[sub e] at T[sub s] = 10 °C),
obtained from both annual nighttime and daytime R[sub e] – T[sub s] relationships, increased linearly
with increasing soil moisture when averaged over the active growing season (April 1 -
Sept 30). However, the effect of soil moisture on R[sub e] shown on the multi-year scale could
not be detected on the seasonal or annual scale probably as a result of the confounding
effects of other environmental factors on R[sub e].
The effective PAR (Q[sub e]) contributing to canopy P in this Douglas-fir canopy was
well described as Q[sub d0] + kQ[sub b0], with Q[sub d0] and Q[sub b0] being sky diffuse and direct PAR,
respectively. The parameter k, which accounts for the total scattering of Q[sub b0] and the non-scattering
effect (e.g., penumbral light spreading) of the solar rays, was found to be
approximately 0.22 for this stand. While the Michaelis-Menten equation (the MM model)
(i.e., P = αQ[sub t0])A[sub max]/(αQ[sub t0]+A[sub max]), where Q[sub t0] = Q[sub d0] + Q[sub b0]) results in significant
overestimation of P in sunny conditions and significant underestimation of P in cloudy
conditions, its modification into P = αQ[sub e])A[sub max]/(αQ[sub e]+A[sub max]) (the Q[sub e]-MM model)
eliminated these systematic errors. When k = 1, the Q[sub e]-MM model reduces to the MM
model. The Q[sub e] - MM model is a single big-leaf model, but it avoids the type of errors made
in earlier generations of single big leaf models of canopy P, i.e., using APAR (the total
absorbed PAR by the canopy) to calculate P. The simplicity of the Q[sub e]-MM model makes
it convenient to be incorporated into large-scale carbon climate models. This study also shows that the widely used sun/shade model developed by de Pury
and Farquhar (1997) is inadequate, mainly because the sun/shade model fails to account
for the incidence angle between the solar beam and individual sunlit leaves. As with the P
modeled using the MM model, the modeled P obtained using the sun/shade model has
significant systematic errors with respect to Q[sub d0]/Q[sub t0] (the ratio of Q[sub d0] to Q[sub t0]). In contrast,
using the Q[sub e]-MM model to estimate canopy P for this Douglas-fir stand eliminated these
systematic errors with respect to Q[sub d0]/Q[sub t0]. In addition, the Q[sub e] -MM model developed in this
study agrees with the detailed multilayer model of canopy P developed by Norman and
Arkebauer (1991) for agricultural crops (i.e., soybean and corn).Land and Food Systems, Faculty of
Graduate
44
Pereira, Leonardo Regis. "Dinâmica do nitrogênio amídico (15N-uréia) ou amoniacal (15N-aquamônia) no solo aplicado conjuntamente com o co-produto da produção do ácido glutâmico (Ajifer)." Universidade de São Paulo, 2008. http://www.teses.usp.br/teses/disponiveis/64/64134/tde-07122009-164411/.
Abstract:
Com objetivo de estudar o efeito da adubação nitrogenada líquida aplicada sobre a palha em solo cultivado com cana-de-açúcar utilizando o co-produto da fabricação do ácido glutâmico (Ajifer), foi implantado um experimento em tubos de PVC de 100 mm no sistema confinado, simulando área com colheita mecanizada de cana-crua e área com colheita com despalha à fogo na fazenda experimental da Apta, Pólo Regional Centro Sul, em Piracicaba, SP. O fertilizante organomineral: Ajifer foi utilizado como veiculo para as fontes uréia (N-amídico) ou aquamônia (N-amoniacal) marcadas com 15N. Este experimento contou com, (i) fase laboratorial, desenvolvimento de formulações dos fertilizantes líquidos, utilizando o co-produto da fabricação do ácido glutâmico (Ajifer) e água como veículo (solvente), e uma das fontes de N: uréia ou aquamônia (soluto), e (ii) fase de aplicação das formulações em campo, em experimento com cinco tratamentos subdivididos em: aplicação do fertilizante sobre a palhada e aplicação sobre o solo, sendo que, cada tratamento foi implantado na forma confinada, com tubos de 250 mm de comprimento com 100 mm de diâmetro e composto com quatro repetições: (T1) testemunha sem adubação; (T2) Uréia (marcado com 15N) + KCl; (T3) Ajifer + Uréia (marcado com 15N) + KCl; (T4) Ajifer + Aquamônia (marcado com 15N) + KCl; (T5) Ajifer + Uréia (marcado com 15N) + Vinhaça Concentrada. As quantidades de nitrogênio foram corrigidas para que não ocorresse diferença entre os tratamentos. Este trabalho permitiu concluir que: a formulação de fertilizantes líquidos utilizando o Ajifer in natura na mistura com as fontes de nitrogênio amídico (Uréia) ou amoniacal (Aquamônia) é viável e apresenta estabilidade física e química, não ocorrendo perda de nitrogênio até 120 horas após a mistura, e que a formulação contendo Ajifer + Uréia + KCl aplicada sobre a palhada da cana-de-açúcar, apresentou a maior recuperação de nitrogênio total, e isto deveu-se a grande capacidade da palhada da cana-de-açúcar de reter NH4+ de fonte amídicaWith objective of studying the effect of the nitrogen liquid fertilizer applied on the straw in the soil cultivated with sugarcane using the co-product of the production of the glutamic acid (Ajifer), an experiment will be implanted in tubes of pvc of 100mm in the confined system, simulating area with automated crop of cane-raw and area with crop with straw to fire in the experimental farm of APTA/ Center South Regional Pole using the fertilizer organomineral, co-product of the production of the glutamic acid (Ajifer), as vehicle for the sources urea (N-amidic) and aquamônia (N - ammoniacal) labeled with 15N. The experiment will count with, (i) laboratorial phase, development of formulations of liquid fertilizers, using the co-product of the production of the glutamic acid (Ajifer) and water as vehicle (solvent), and two sources of nitrogen (solute), and (ii) field phase of application of the formulations in field, and it is phase will count with five treatments subdivided in: application of the fertilizer on the straw and applied on the soil, and, each treatment will be implanted in the confined form, with tubes of 250 length mm with 100 diameter mm and composed with four repetitions: (T1) without fertilizer, (T2) co-product of the production of the glutamic acid (Ajifer) + urea (labeled with 15N) + KCl; (T3) co-product of the production of the glutamic acid (Ajifer) + aquamônia (labeled with 15N) + KCl; (T4) co-product of the production of the glutamic acid (Ajifer) + urea (marked with 15N) + concentrated vinhaça. The amounts of nitrogen were corrected so that it didn\'t happen difference among the treatments. This work allowed to end that: the formulation of liquid fertilizers using Ajifer in nature in the mixture with the sources of nitrogen amidic (Urea) or ammoniacal (Aquamônia) it is viable and it presents physical and chemical stability, not happening loss of nitrogen up to 120 hours after the mixture, and that the formulation containing Ajifer + Urea + applied KCl on the on the straw of the sugarcane, presented the largest recovery of total nitrogen, and this if the great capacity of the straw of the sugarcane to keep NH4 + of source amidic
45
Pinelli, Milena Santos. "Estimativa de valores de referência para Cd, Co, Cr, Cu, Ni, Pb,e Zn em solos do entorno da Baía do Iguape, Bahia, Brasil." reponame:Repositório Institucional da UFBA, 2012. http://www.repositorio.ufba.br/ri/handle/ri/11731.
Abstract:
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CAPES
Os metais têm origem natural como componentes das rochas e nesta situação não apresentam riscos aos seres vivos. Atualmente existem poucos estudos relacionados à obtenção de valores de referência para concentrações naturais de metais em solos do Brasil, o que dificulta a ação dos órgãos fiscalizadores e algumas instituições em monitorarem os ambientes que podem ter sido contaminados por indústrias ou outros tipos de empreendimentos. Este trabalho teve como objetivo propor valores de referência para concentração dos metais Cd, Co, Cr, Cu, Pb, Mn, Ni e Zn em solo do entorno na Baía do Iguape. As amostras foram digeridas em forno de micro-ondas com cavidade utilizando o procedimento da Agência de Proteção Ambiental, EPA 3051A e para as determinações dos analitos foi empregada a espectrometria de emissão óptica com plasma indutivamente acoplado (ICP OES). As linhas de emissão selecionadas foram, em nm: Cd II 226,502; Co II 228,615 nm; Cr II 267,716; Cu Il 213,598; Mn II 257,610; Ni II 216,555; Pb II 220,353; e Zn I 213,857. A validação foi feita avaliando-se os limites de detecção (LOD) e de quantificação (LOQ), a faixa linear de trabalho, precisão, análise de material de referência certificado e testes de adição e recuperação. O procedimento validado foi aplicado na caracterização dos solos formados a partir de sedimentos da Formação Barreiras, Arenito e Folhelho, quanto às concentrações dos analitos Cd, Co, Cu, Cr, Mn, Ni, Pb e Zn no entorno da Baía de Iguape. As faixas de concentrações obtidas para as áreas estudadas foram, em mg kg-1: Barreiras encosta: Cd (0,57 - 1,7), Co (4,5 - 5,7), Cr (33 - 73), Cu (7,0 - 16), Mn (74 - 123), Ni (5,0 - 13), Pb (4,8 - 16) e Zn (12 - 30); Barreiras plana: Cd (0,20 - 0,67), Co (1,3 - 2,2), Cr (23 - 48), Cu (3,2 - 4,8), Mn (46 - 56), Ni (4,2 - 12), Pb (2,5 - 8,3) e Zn (12 - 24); Arenito 1 Cd (0,12 - 0,43), Co (0,30 - 0,90), Cr (4,9 - 14), Cu (1,7- 4,1), Mn (12 - 30), Ni (1,2 - 3,7), Pb (2,7 - 7,5) e Zn (1,8 - 8,6); Arenito 2 : Co (0,7- 2,0), Cr (5,6 - 19,8), Cu (1,7 - 3,1), Mn (10 - 28), Ni (1,9 - 4,0), Pb (1,7 - 4,4) e Zn (1,7 - 6,5); Arenito 3 Cd (0,10 - 0,23), Co (0,40 - 1,5), Cr (2,9 - 12), Cu (1,2 - 4,5), Mn (15 - 31), Ni (1,0 - 4,0), Pb (2,6 - 6,6) e Zn (2,1 - 7,3); Folhelho Cd (0,32 - 1,1), Co (0,92 - 1,7), Cr (37 - 63), Cu (3,6 - 7,2), Mn (27 - 39), Ni (4,4 - 9,3), Pb (3,2 - 11) e Zn (10 - 18). De um modo geral as concentrações obtidas variaram na seguinte ordem decrescente Barreiras> Folhelho> Arenito. Para propor valores de referência para solos com características similares aos analisados, foram selecionadas as áreas Barreira encosta e Arenito 3 e aplicou-se a correlação linear de Pearson e análise de componentes principais (PCA), para selecionar quais parâmetros (metais e atributos) contribuem de forma efetiva para a elaboração das equações do modelo estatístico. As concentrações das amostras foram estimadas de forma satisfatória com as equações elaboradas. Para os solos de Barreiras encosta apenas Co e Pb não apresentaram valores confiáveis de predição enquanto que para o Arenito 3, somente Ni não apresentou resultados confiáveis, devido ao seu baixo coeficiente de determinação.
Salvador
46
Chelladurai, Jennifer. "Using Keeling Plots to Trace δ13C and δ18O of CO2 Through Processes of Heterotrophic Respiration, Diffusion and Soil Water Equilibration in Artificial C3- and C4-Grassland Soils." Scholar Commons, 2009. https://scholarcommons.usf.edu/etd/1896.
Abstract:
Global carbon cycle dynamics and fluxes of CO2 between biosphere and atmosphere have been progressed through the use of Keeling Plots. Processes that control and effect the isotopic composition of soil-respired CO2, soil CO2, and equilibrated soil carbonate are specifically addressed in this study through the use of Keeling Plots. Replicate grassland soil profiles containing either C3 or C4 homogenized organic matter were constructed and maintained under controlled settings to encourage the production of soil-respired CO2 and the precipitation of pedogenic carbonate. Soil CO2 was sampled over five months and analyzed with IRMS. Keeling Plots illustrated source CO2 affected by mixing with atmospheric CO2 near the surface and equilibration with ¹³C-depleted CO2 at depth in the zone of likely carbonate precipitation. The δ13C Keeling Plot intercepts for the surface horizons (~ -24.7 per mil for C3 profiles and ~ -11.1 per mil for C4 profiles) follow the diffusion-production model when corrected with a constant 4.4 per mil diffusional fractionation, but the Keeling Plot intercepts for developing Bk horizons were curved towards depleted values (~ -36.2 per mil for C3 profiles and ~ -18.4 per mil for C4 profiles). This change in isotopic composition with depth deviates from the usual interpretations of Keeling Plots (steady-state, source to background diffusional mixing). δ13C Keeling Plot intercepts indicated evaporative enrichment in the surface horizons of C3 and C4 profiles). This study uses Keeling Plots as a measure of mixing to assess the efficacy of steady-state diffusion-production models of soil CO2 equilibration with soil carbonate.
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Gryń, Grzegorz. "Mikrobiologiczna ocena skuteczności higienizacji procesu kofermentacji metanowej gnojowicy, substratów roślinnych i odpadów poubojowych." Rozprawa doktorska, Uniwersytet Technologiczno-Przyrodniczy w Bydgoszczy, 2014. http://dlibra.utp.edu.pl/Content/573.
Abstract:
Celem pracy była mikrobiologiczna ocena skuteczności higienizacji procesu kofermentacji metanowej. Dokonano oceny wpływu cieczy pofermentacyjnej na właściwości mikrobiologiczne i fizykochemiczne nawożonych gleb. Materiał do badań stanowiły: gnojowica świńska, kiszonka kukurydziana i opcjonalnie odpady mięsne, które poddano procesowi kofermentacji metanowej w warunkach mezo- i termofilnych. Przeprowadzona została analiza wartości nawozowych pofermentu w oparciu o wzrost i plonowanie gorczycy białej. Wykazano różnice w eliminacji drobnoustrojów patogennych i jaj pasożytów A. suum w trakcie przebiegu procesów kofermentacji gnojowicy
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Lee, Sungeun. "Virus-host interactions across a soil pH gradient at the community and individual scale." Thesis, Lyon, 2020. http://www.theses.fr/2020LYSEC020.
Abstract:
Les virus du sol sont capables d'influencer la structure de la communauté microbienne et le fonctionnement de l'écosystème en affectant l'abondance des cellules hôtes par lyse et par leurs caractéristiques à transférer des gènes entre les hôtes. Bien que notre compréhension sur la diversité et la fonction virales s’améliore, la connaissance des interactions hôte-virus dans le sol reste limitée. Pour mieux comprendre les interactions hôte-virus, un gradient du sol à long terme manipulé par le pH dans lequel la communauté microbienne change à travers, a été étudié. Les principaux objectifs de cette thèse ont consisté à (1) déterminer l'influence de la structure de la communauté microbienne et du pH du soil sur les virus par séquençage d’ADN haut-débit (Chapitre II), (2) déterminer l’infectivité des populations virales à partir de niches de sol co-localisées et non co-localisées avec son hôte grâce à une approche de l’essai de plaque combinée à un séquençage hybride (Chapitre III), (3) identifier les populations virales infectant des groupes fonctionnels microbiens spécifiques du sol, en particulier les méthanotrophes (Chapitre IV) et les nitrifiants (Chapitre V ), à l’aide d’une sonde isotopique stable à l'ADN. Nos premiers résultats ont montré que la structure de la communauté virale change selon le pH du sol, ce qui souligne que la communauté virale est étroitement liée aux populations hôtes. L’analyse de CRISPR systèmes a révélé des interactions virus-hôte dynamiques, avec le nombre et la taille des CRISPR systèmes distincts selon le soil à pH contrasté. L’analyse taxonomique de cette CRISPR systèmes suggère que les virus jouent un rôle essentiel dans la composition et de la fonction de la communauté procaryote du sol. Les processus co-évolutionnaires entre l'hôte (le système de restriction-modification et le CRISPR-Cas système) et les populations virales co-localisées (la mutation d’une séquence espaceur « spacer » et la méthyltransférase codée par le virus) fournissent des preuves de l'adaptation locale et que les interactions virus-hôte jouent un rôle important dans la susceptibilité d'un hôte à l'infection et par conséquent la régulation des populations bactériennes du sol. L'ADN-SIP-métagénomique ciblant des groupes fonctionnels microbiens spécifiques a permis l’analyse des populations hôte-virus individuelles. Le suivi du flux de carbone à travers les populations procaryotes et virales a révélé des interactions actives entre les virus et les hôtes méthanotrophes et nitrifiants, et les préférences de niches de pH du sol. Notre étude a montré une preuve de transfert horizontal de gènes et des gènes métaboliques auxiliaires codés par le virus, indiquant que les virus contribuent de manière significative aux cycles biogéochimiques dans le sol, tels que le carbone (les gènes qui codent pour les familles GH, peptidases et la sous-unité C de méthane monooxygénase particulaire), et l'azote (les gènes qui codent pour la nitrogénase et le cytochrome cd1-nitrite réductase). Dans l’ensemble, ces résultats ont montré que les virus du sol sont des régulateurs importants des communautés microbiennes par la lyse spécifique de l’hôte et des interactions dynamiques virus-hôteSoil viruses have potential to influence microbial community structure and subsequent ecosystem functioning by directly affecting the abundance of host cells by lysis and through their ability to transfer genes between hosts. Although our understanding of soil viral diversity and functioning has increased, the role of viruses and their interactions with prokaryotes in soil is limited. To gain a better understanding of virus-host interactions in soil, a long-term pH-manipulated soil gradient, which microbial community structure changes across, was investigated. The main objectives of this thesis were to 1) determine the influence of microbial community structure and soil pH on viruses using metagenomics and viromics (Chapter II), 2) determine the infectivity of soil viral populations from co-localized and foreign pH soil niches using a plaque assay approach combined with hybrid metagenomics sequencing (Chapter III) and 3) identify virus populations infecting specific soil microbial functional groups, specifically methanotrophs (Chapter IV) and nitrifiers (Chapter V), using DNA stable isotope probing combined with metagenomic deep sequencing. Viral community structure was found to change with soil pH, demonstrating that viral communities are tightly linked to host populations, but also may have narrow host ranges. Analysis of clustered regularly interspaced short palindromic repeats (CRISPR) arrays revealed dynamic virus-host interactions, with the number and size of CRISPR arrays distinct across contrasting pH soil. Profiling of the host-virus linkages between soil pH, suggests that viruses play a critical role in shaping the composition and function of the soil prokaryotic community. Surprisingly, greater infectivity of a host bacterium by virus populations was found when viruses and host bacterium were not co-localized in the same pH soil. Coevolutionary processes between the host and virus populations, such as restriction modification/virus-encoded methyltransferase and CRISPR-Cas system/spacer mutation, provide evidence for local adaptation, and that virus-bacterial host interactions play an integral part in the susceptibility of a host to infection and consequently in the regulation of soil bacterial populations. Targeting specific microbial functional groups via stable isotope probing allowed analysis of individual host-virus populations. Tracking carbon flow through prokaryotic and viral populations revealed active interactions between viruses and methanotroph and nitrifier hosts, and soil pH niche preferences. Evidence of horizontal gene transfer and virus-encoded auxiliary metabolic genes, such as glycoside hydrolase families, peptidases, particulate methane monooxygenase subunit C (pmoC), nitrogenase (nifH) and cytochrome cd1-nitrite reductase, supports that viruses are significant contributors to host functioning and carbon and nitrogen cycling in soil. Overall, this work demonstrated that soil viruses are important regulators of microbial communities through specific host lysis and dynamic virus-host interactions
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Adisaputro, Didi. "Metrology and Monitoring of Gases Transfer (CO₂ and CH₄) Processes within the System of Geosphere and Biosphere." Electronic Thesis or Diss., Université de Lorraine, 2021. http://www.theses.fr/2021LORR0313.
Abstract:
Ce travail de recherche s'inscrit dans le prolongement de différentes études conduites notamment dans le cadre du pilote de Capture Transport et Stockage du CO₂ (pilote Total CCS, Lacq- Rousse, France) relatives au suivi des mécanismes de transfert des gaz (CO₂ et CH₄) dans les compartiments Géosphère/Biosphère/Atmosphère. De ces études, il était ressorti que l'évolution de la fraction molaire de CO₂ (χc) dans le sous-sol karstique du plateau du Jurançon était négativement corrélée aux battements de la nappe phréatique située à -45m via des mécanismes de dissolution/dégazage. Cependant, il n'est pas encore clair si cette relation existe dans l'écosystème forestier, qui représente importante de l'échange de CO₂ atmosphérique. Dans ce contexte, cette thèse se concentre sur la surveillance des échanges gazeux et de leurs processus de transport au sein de la zone critique, entre le sous-sol (-6 m), le sol (-1 m) et le couvert végétal (+50m). Nous avons développé et mis en place un système de surveillance géochimique in situ en puits dédiés pour le suivi continu de la fraction molaire de CO₂ dans le sous-sol et le sol couplé à un système de surveillance micrométéorologique utilisant une tour de flux préétablie dans l'écosystème forestier (Montiers, Région Lorraine, France). Au cours des périodes d'étude allant de Juin 2018 à Décembre 2020, l'écosystème a agi comme un puits de carbone net avec une moyenne annuelle des paramètres d’échange d'écosystème net (NEE), de productivité primaire brute (GPP) et de respiration de l'écosystème (Reco) de -453±122 gC m-2y-1, -1468 ±109 gC m-2y-1, et 1052 ±88 gC m-2y-1 respectivement. L’échange de carbone, les données météorologiques et les facteurs environnementaux durant les épisodes de sécheresse ont été comparés aux données de référence à long terme enregistrées durant les années allant de 2014 à 2017. Contrairement à certaines recherches précédentes où les paramètres NEE et Reco ont diminué parallèlement pendant les épisodes de sécheresse, les données enregistrées sur site ont montré que le paramètre Reco est plus sensible à la sécheresse que le paramètre NEE, ce qui a entraîné une augmentation significative de l'échange net au sein de l'écosystème. Ainsi, durant les périodes de sécheresses d’été et d’automne (2018-2019), le paramètre de respiration de l’écosystème (Reco) a diminué de 20 %, et 26 % par rapport aux années de référence (2014-2017). Les traitement statistique des données comparées sous-sol/sol/couvert végétal, montre des preuves empiriques solides que la turbulence du vent, mesurée au travers du paramètre de vitesse de frottement (u*) joue un rôle important dans la variabilité des concentrations de CO₂ dans les sols même jusqu’à des profondeurs de -6m, ce qui n’avait jamais été établi. Nous supposons que cela pourrait être dû aux effets de pompage de la pression qui diminue la fraction molaire de CO₂ dans le sol lors de fortes turbulences et augmente le stock age du CO₂ dans les sols profonds lors de faibles turbulences. Cette étude a aussi démontre le rôle de l’hydrométrie du sol sur ces processus d’échanges. En effet, en périodes humides, la perméabilité est considérablement réduite ce qui diminue la diffusion et l'advection moléculaires. Cette étude a également révélé une forte influence biotique sur la production de CO₂. Les valeurs de δ¹³CCO₂ dans le sous-sol de notre site peuvent être attribuées à la respiration et à la décomposition des plantes en C3. Ces origines biologiques du CO₂ du sol entraine très probablement des augmentations de la densité de l'air ce qui conduit à faire migrer le CO₂ stocké vers les couches plus profondes du sol par le biais d’un mécanisme de percolation gravitationnelle. La relation des gaz du sous-sol souligne également que les composants biogéniques dominent les origines et le processus de contrôle du CO₂ du sous-sol alors que le processus géochimique joue un rôle insignifiantThis study is a continuation of our previous geochemical monitoring finding at the injection wells of Rousse 1 ( Total CCS pilot, Lacq- Rousse, France) where it was identified that the soil CO₂ mole fraction (χc) evolution in subsoil was negatively correlated with the level of the water table and the CO₂ sources were attributed to the CO₂-rich aquifers. However, it is still unclear whether this relationship exists in the forest ecosystem, representing a significant proportion of the CO₂ atmospheric budget. For this reason, this thesis focuses on monitoring the gas exchange and its main driver of the transport process between soil (-1 m), subsoil (-6 m), and biosphere. We developed and implemented an in-situ geochemical monitoring system for continuous monitoring of CO₂ mole fraction in the subsoil coupled with a micrometeorological monitoring system using a pre-established flux tower in the forest Ecosystem (Montiers, Lorraine Region, France). This soil gas measurement infrastructure combining borehole measurement with micrometeorological measurement offers great possibilities for long-term in-situ and continuous gas monitoring to derive the vertical distribution of CO₂. Thus, this infrastructure allowed the observation of the temporal dynamics in soil-gas CO₂ research. During the study periods, the ecosystem acted as a net carbon sink with a mean annual NEE, GPP, and Reco of -453±122 gC m-2y-1, -1468 ±109 gC m-2y-1, and 1052 ±88 gC m-2y-1 consecutively. The Carbon exchange, climate, and environmental drivers during the drought episodes were compared with long-term reference data recorded from 2014 to 2017. In contrast with some previous research where GPP and Reco parallelly decreased during the drought episodes, our site showed Reco is more sensitive to drought than GPP, resulting in a significant increase in Net Ecosystem exchange. Reco decreased by 20%, and 26% were found in Summer and Autumn (2018-2019) relative to the ref erence years (2014-2017). This study shows strong empirical shreds of evidence that wind turbulence plays a significant role in driving the deep soil CO₂ concentration. We hypothesize that this could be due to pressure pumping effects where it decreases the CO₂ molar fraction in the soil during high turbulence and increasing the CO₂ storage in deep soil during low turbulence. This study also demonstrates that permeability significantly reduced during wet periods diminishing molecular diffusion and advection. This study also revealed a strong biotic influence on CO₂ production. The δ¹³CCO₂ values in our site subsoil can be attributed to respiration and decomposition of the C3 plants. These biological origins of soil CO₂ are highly likely increases air density resulting in gravitational percolation that leads the CO₂ stored in a deeper layer of soil. The relationship of subsoil gases also emphasizes that biogenic components dominate the origins and controlling process of subsoil CO₂ while the geochemical process plays an insignificant role
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Babos, Diêgo Victor de [UNESP]. "Determinação de Co, Mo, Ni e V em material vegetal e solo por espectrometria de absorção atômica com fonte contínua e de alta resolução em forno de grafite empregando amostragem direta de sólidos." Universidade Estadual Paulista (UNESP), 2016. http://hdl.handle.net/11449/142860.
Abstract:
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Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)
Avaliou-se a amostragem direta de sólidos como base de métodos analíticos simples, rápidos e mais limpos para determinar Co, Mo, Ni e V em tecido vegetal e solo empregando a espectrometria de absorção atômica de alta resolução com fonte contínua. Esta técnica foi escolhida devido as suas características peculiares, especialmente a elevada capacidade de correção de fundo. Na determinação de cobalto em material vegetal, a sobreposição espectral de SiO(g) na linha 240,725 nm do Co foi corrigida pelo método dos mínimos quadrados. Curvas de calibração (0–540 pg) com bons coeficientes de correlação lineares (R 0,9993) foram obtidas com padrões sólidos. O limite de detecção (LOD) foi 3 pg Co. Na determinação simultânea de Mo e Ni em material vegetal, empregou-se Co como padrão interno para Ni. Curvas de calibração (0,8-50 ng Ni; 0-0,33 ng Mo) lineares (R 0,9937) foram obtidas com padrões aquosos sem modificador químico. Os LODs foram 0,018 ng Mo e 0,025 ng Ni. A padronização interna aumentou a precisão das medidas para Ni de 62-135% para 94-105%. Vanádio e Co foram determinados em solos empregando NH4F como modificador. As calibrações, com padrões aquosos para V (0-40 ng), e por compatibilização de matriz para Co (0-5,0 ng), forneceram R 0,9979. Os LODs foram 0,044 ng Co e 0,43 ng V. Na determinação de Mo e Ni em solo, o modificador Mg(NO3)2 foi utilizado apenas para Ni. As curvas de calibração aquosas (0-500 ng Ni; 0-0,54 ng Mo) forneceram R 0,9953. Na determinação do Ni foi monitorado o tripleto em 341,377 nm, 341,347 nm e 341,394 nm, permitindo determinar Ni em ampla faixa de concentração. Os LODs foram 0,0082 ng Mo (313,259 nm), 0,021 ng Ni (341,477 nm),1,8 ng Ni (341,347 nm). A exatidão dos métodos foi avaliada via análise de materiais de referência certificados de solos e plantas. De uma forma geral, os resultados obtidos foram concordantes com os valores certificados ao nível de confiança de 95%.
High-resolution continuum source atomic absorption spectrometry with direct solid sampling was employed for the development of simple, fast and clean analytical methods for Co, Mo, Ni and V determination in soil and plant materials. The technique has as main advantages the efficiency to correct background absorption. For cobalt determination in plant material, a spectral overlap of SiO molecular absorption in Co line was corrected by using least squares background correction method. Calibration curves (0-540 pg) with correlation coefficients higher of 0.9993 were obtained with solid standards. The limit of detection was of 3 pg Co. For simultaneous determination of Mo and Ni in plant material Co was employed as internal standard for Ni. Calibration curves (0.8-50 ng Ni; 0-0.33 ng Mo) with correlation coefficients higher of 0.9937 were obtained with aqueous standards without chemical modifier. The LODs were 0.025 and 0.018 ng for Mo and Ni, respectively. The internal standardization increased the accuracy of Ni determinations from 62-135% to 94-105%. For V and Co determinations in soils the NH4F was used as chemical modifier. The calibration with aqueous standards for V (0-40 ng), and compatibility matrix for Co (0-5.0 ng), provided linear correlation coefficients better of 0.9979. The LODs were 0.044 and 0.43 ng for Co and V, respectively. For Mo and Ni determination in soil the Mg(NO3)2 was used as chemical modifier for Ni. The aqueous calibration curves (0-500 ng Ni; 0-0.54 ng Mo) provided linear correlation coefficients higher of 0.9953. For Ni determination were used the triplet lines at 341.377 nm, 341.347 nm and 341.394 nm, allowing the determination of Ni in wide concentration range. The calculated LODs were 0.0082 ng Mo (313.259 nm), 0.021 ng Ni (341.477 nm), 1.8 ng Ni (341.347 nm). The accuracy of the proposed methods was assessed by analysis of certified reference materials of soils and plants. In general, the results were in agreement with the certified values at 95% confidence level (t-test).