Journal articles on the topic 'Particulate organic carbon'
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Mugica-Á lvarez, Violeta, Sandra Ramos-Guízar, Naxieli Santiago-de la Rosa, Miguel Torres-Rodríguez, and Luis Noreña-Franco. "Black Carbon and Particulate Organic Toxics Emitted by Sugarcane Burning in Veracruz, México." International Journal of Environmental Science and Development 7, no. 4 (2016): 290–94. http://dx.doi.org/10.7763/ijesd.2016.v7.786.
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Tiwari, Neha, and Namita Joshi. "Carbon Management Index and Soil Organic Carbon pools of Different land use in Uttarakhand, Western Himalaya." Current World Environment 17, no. 3 (December 30, 2022): 585–91. http://dx.doi.org/10.12944/cwe.17.3.7.
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Himalayan soils are young, unstable and prone to erosion due to its terrain, climate responsive conditions and human activities. Thus, a research was conducted to assess the dynamics of total organic carbon, particulate organic carbon, labile and non-labile carbon, lability index and carbon management index among three distinct landuse at various soil depth in north himalayan region. Mixed forest have considerably more total organic carbon (43.0 g/kg), particulate organic carbon (5.45 g/kg) followed by agricultural total organic carbon (29.58 g/kg), particulate organic carbon (3.51 g/kg) and tea garden total organic carbon (21.96 g/kg), particulate organic carbon (2.42 g/kg). There is a greater accumulation of all the indices and carbon pools at the surface layer in all landuse system. Mixed forest have higher lability index (0.77) and carbon management index (67.76) value indicating better soil health and quality. Therefore mixed forest is considered as the best landuse system in mitigating climate change through carbon storage. This study provides key details for conservation framing and reducing land deterioration in mountainous regions.
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Kumari, Radha Karuna, and P. M. Mohan. "Review on Dissolved Organic Carbon and Particulate Organic Carbon in Marine Environment." ILMU KELAUTAN: Indonesian Journal of Marine Sciences 23, no. 1 (March 3, 2018): 25. http://dx.doi.org/10.14710/ik.ijms.23.1.25-36.
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Quantification the Dissolved and Particulate organic carbon in marine waters is an essential step towards ecosystem modeling and understanding carbon sequestration processes. A detailed view of estimated and recorded carbon concentration from Arctic to Antarctic is the prime goal of this review. This review compiles some of the important research work carried out in quantifying the organic carbon available in off shore and open waters and in coral reef environment. The cited literatures were collected, grouped and carefully analyzed to give a comprehensive view on current status of marine environment with regard to distribution of dissolved and particulate organic carbon. Keywords: DOC, POC, continental shelf waters, open sea waters, coral reef environment.
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Janning, K. F., K. Mesterton, and P. Harremoës. "Hydrolysis and degradation of filtrated organic particulates in a biofilm reactor under anoxic and aerobic conditions." Water Science and Technology 36, no. 1 (July 1, 1997): 279–86. http://dx.doi.org/10.2166/wst.1997.0065.
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Two experiments were performed in order to investigate the anoxic and the aerobic degradation of filtrated organic matter in a biofilter. In submerged lab. scale reactors with Biocarbone media as filter material, accumulated particulate organic matter from pre-settled wastewater served as the only carbon source for anoxic and aerobic degradation respectively. In order to utilise the accumulated organic matter, the bacteria in the biofilm had to produce extracellular hydrolytic enzymes for the hydrolysis process. In the first experiment with anoxic degradation, a significant denitrification occurred. The maximum nitrate removal rate, with particulate organic matter as carbon source, was found to 1 g NO3-N/ (m2d), declining exponentially as rA.NO3-N = 1.04 e −4t g NO3-N/(m2d) (t = days). A significant release of soluble organic matter (< 0.45 μm) and production of inorganic carbon to the bulk liquid was observed as an indication of hydrolysis taking place. The second experiment was designed as a series of on-line OUR batch experiments in a biofilm reactor with recirculation, in order to investigate further the degradation of particulate organic matter. After the biofilm had been starved in order to remove the original organic matter, particulate organic matter was added and the degradation kinetics recorded. The initial removal rate was high, rA.02 = 2.1 g O2/(m2d) though fast declining towards endogenous respiration. The respiration ratio between removed oxygen and produced carbon dioxide was declining from 1.3 to 1.0 g O2/g CO2 during the degradation of organic particulates. The respiration ratio during endogenous respiration was determined to be 0.7 g O2/g CO2 indicating a thorough mineralisation of biomass.
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Zhu, Gen Hai, Yan Lan Liu, Li Hong Chen, Pei Song Yu, Mao Jin, and Zi Lin Liu. "Studies on Phytoplankton and Particulate Organic Carbon in the Southern Ocean." Applied Mechanics and Materials 137 (October 2011): 344–52. http://dx.doi.org/10.4028/www.scientific.net/amm.137.344.
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Using China Southern Ocean’s study data collected from 1989 to 2009 year, this paper analyzed the related characteristics between phytoplankton abundance, Ch1 a concentrations and particulate organic carbon. The average cell abundance of Southern Ocean phytoplankton was 7.38×104 cells/dm3. The dominant species of Southern Ocean phytoplankton were Fragilariopsis kerguelensis, Fragilariopsis curta, Pseudo-nitzschia lineola, Eucampia antarctica, Thalassiosira antarctica and Corethron criophilum and son on. In Prydz Bay of the Southern Ocean, the contribution of phytoplankton cell abundance and phytoplankton carbon toward particulate organic carbon were higher than that in the Northern Gulf Ocean Area. In the upper layer of euphotic zone, the contribution of phytoplankton abundance and phytoplankton carbon toward particulate organic carbon were higher than that in the deep water district. Through analysis of regressive statistics, phytoplankton cell abundance (y) and particulate organic carbon (POC) and chlorophyll a (Chl a) were a remarkable positive correlation.
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Shukla, Pravesh Chandra, Tarun Gupta, Nitin Kumar Labhsetwar, and Avinash Kumar Agarwal. "Development of low cost mixed metal oxide based diesel oxidation catalysts and their comparative performance evaluation." RSC Advances 6, no. 61 (2016): 55884–93. http://dx.doi.org/10.1039/c6ra06021h.
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A four cylinder diesel engine was used to evaluate the performance of two non-noble metal based diesel oxidation catalysts for emission parameters such as particulate mass, elemental/organic carbon (EC/OC), and trace-metal content in particulates.
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Saavedra-Hortua, Daniel A., Daniel A. Friess, Martin Zimmer, and Lucy Gwen Gillis. "Sources of Particulate Organic Matter across Mangrove Forests and Adjacent Ecosystems in Different Geomorphic Settings." Wetlands 40, no. 5 (February 6, 2020): 1047–59. http://dx.doi.org/10.1007/s13157-019-01261-9.
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Abstract Mangrove forests are among the world’s most productive ecosystems and provide essential ecosystem services such as global climate regulation through the sequestration of carbon. A detailed understanding of the influence of drivers of ecosystem connectivity (in terms of exchange of suspended particulate organic matter), such as geomorphic setting and carbon stocks, among coastal ecosystems is important for being able to depict carbon dynamics. Here, we compared carbon stocks, CO2 fluxes at the sediment-air interface, concentrations of dissolved organic carbon and suspended particulate organic carbon across a mangrove-seagrass-tidal flat seascape. Using stable isotope signatures of carbon and nitrogen in combination with MixSIAR models, we evaluated the contribution of organic matter from different sources among the different seascape components. Generally, carbon concentration was higher as dissolved organic carbon than as suspended particulate matter. Geomorphic settings of the different locations reflected the contributions to particulate organic matter of the primary producers. For example, the biggest contributors in the riverine location were mangrove trees and terrestrial plants, while in fringing locations oceanic and macroalgal sources dominated. Anthropogenic induced changes at the coastal level (i.e. reduction of mangrove forests area) may affect carbon accumulation dynamics in adjacent coastal ecosystems.
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Galy, Valier, and Christian France-Lanord. "Particulate organic carbon transport during Himalayan erosion." Geochimica et Cosmochimica Acta 70, no. 18 (August 2006): A191. http://dx.doi.org/10.1016/j.gca.2006.06.385.
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Guzmán-Uria, Fabiola, Isabel Morales-Belpaire, Dario Achá, and Marc Pouilly. "Particulate Mercury and Particulate Organic Matter in the Itenez Basin (Bolivia)." Applied Sciences 10, no. 23 (November 26, 2020): 8407. http://dx.doi.org/10.3390/app10238407.
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In rivers and other freshwater bodies, the presence of mercury can be due to direct contamination by anthropic activities such as gold mining. However, it can also be attributed to atmospheric deposition and erosion, runoff, or lixiviation from surrounding soils. In the case of the Amazon rainforest, high mercury contents have been reported for litter and topsoil, which could affect the mercury concentrations in water bodies. Samples of suspended particulate matter were obtained from a transect of the Itenez River, associated lakes, and some of its tributaries. The aim was to obtain information on particulate mercury’s origin in the study area and determine the relationship between particulate mercury and particulate organic carbon. The concentration of mercury, organic matter, and the C:N ratio of the suspended matter was determined. The concentration of particulate mercury by water volume depended on changes in suspended matter loads, which in turn were mostly affected by the nature of the watershed or sediment resuspension. The observed values for the percentage of organic matter and the C:N ratio suggest that most of the mercury content in rivers and lakes originated from soils. A positive correlation was found between mercury concentration by weight of particulate matter and organic carbon content in particles. This correlation might be due to the direct binding of mercury to organic matter through functional groups like thiols or to an indirect effect of oxyhydroxides that can adsorb mercury and are associated with organic matter.
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Schartau, M., A. Engel, J. Schröter, S. Thoms, C. Völker, and D. Wolf-Gladrow. "Modelling carbon overconsumption and the formation of extracellular particulate organic carbon." Biogeosciences 4, no. 4 (July 2, 2007): 433–54. http://dx.doi.org/10.5194/bg-4-433-2007.
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Abstract. During phytoplankton growth a fraction of dissolved inorganic carbon (DIC) assimilated by phytoplankton is exuded in the form of dissolved organic carbon (DOC), which can be transformed into extracellular particulate organic carbon (POC). A major fraction of extracellular POC is associated with carbon of transparent exopolymer particles (TEP; carbon content = TEPC) that form from dissolved polysaccharides (PCHO). The exudation of PCHO is linked to an excessive uptake of DIC that is not directly quantifiable from utilisation of dissolved inorganic nitrogen (DIN), called carbon overconsumption. Given these conditions, the concept of assuming a constant stoichiometric carbon-to-nitrogen (C:N) ratio for estimating new production of POC from DIN uptake becomes inappropriate. Here, a model of carbon overconsumption is analysed, combining phytoplankton growth with TEPC formation. The model describes two modes of carbon overconsumption. The first mode is associated with DOC exudation during phytoplankton biomass accumulation. The second mode is decoupled from algal growth, but leads to a continuous rise in POC while particulate organic nitrogen (PON) remains constant. While including PCHO coagulation, the model goes beyond a purely physiological explanation of building up carbon rich particulate organic matter (POM). The model is validated against observations from a mesocosm study. Maximum likelihood estimates of model parameters, such as nitrogen- and carbon loss rates of phytoplankton, are determined. The optimisation yields results with higher rates for carbon exudation than for the loss of organic nitrogen. It also suggests that the PCHO fraction of exuded DOC was 63±20% during the mesocosm experiment. Optimal estimates are obtained for coagulation kernels for PCHO transformation into TEPC. Model state estimates are consistent with observations, where 30% of the POC increase was attributed to TEPC formation. The proposed model is of low complexity and is applicable for large-scale biogeochemical simulations.
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Schartau, M., A. Engel, J. Schröter, S. Thoms, C. Völker, and D. Wolf-Gladrow. "Modelling carbon overconsumption and the formation of extracellular particulate organic carbon." Biogeosciences Discussions 4, no. 1 (January 24, 2007): 13–67. http://dx.doi.org/10.5194/bgd-4-13-2007.
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Abstract. During phytoplankton growth a fraction of dissolved inorganic carbon (DIC) assimilated by phytoplankton is exuded in the form of dissolved organic carbon (DOC), which can be transformed into extracellular particulate organic carbon (POC). A major fraction of extracellular POC is associated with carbon of transparent exopolymer particles (TEP; carbon content = TEPC) that form from dissolved polysaccharides (PCHO). The exudation of PCHO is linked to an excessive uptake of DIC that is not directly quantifiable from utilisation of dissolved inorganic nitrogen (DIN), called carbon overconsumption. Given these conditions, the concept of assuming a constant stoichiometric carbon-to-nitrogen (C:N) ratio for estimating new production of POC from DIN uptake becomes inappropriate. Here, a model of carbon overconsumption is analysed, combining phytoplankton growth with TEPC formation. The model describes two modes of carbon overconsumption. The first mode is associated with DOC exudation during phytoplankton biomass accumulation. The second mode is decoupled from algal growth, but leads to a continuous rise in POC while particulate organic nitrogen (PON) remains constant. While including PCHO coagulation, the model goes beyond a purely physiological explanation of building up carbon rich particulate organic matter (POM). The model is validated against observations from a mesocosm study. Maximum likelihood estimates of model parameters, such as nitrogen- and carbon loss rates of phytoplankton, are determined. The optimisation yields results with higher rates for carbon exudation than for the loss of organic nitrogen. It also suggests that the PCHO fraction of exuded DOC was 63±20% during the mesocosm experiment. Optimal estimates are obtained for coagulation kernels for PCHO transformation into TEPC. Model state estimates are consistent with observations, where 30% of the POC increase was attributed to TEPC formation. The proposed model is of low complexity and is applicable for large-scale biogeochemical simulations.
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Mu, Chongjun, and Wendy S. Wolbach. "Particulate carbon at the cretaceous-tertiary boundary." Proceedings, annual meeting, Electron Microscopy Society of America 44 (August 1986): 782–83. http://dx.doi.org/10.1017/s042482010014525x.
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A worldwide Ir layer occurs at the Cretaceous-Tertiary (K-T) boundary, apparently from the impact of a 10 km meteorite that caused the mass extinctions at that time. The same boundary layer also is enriched in carbon showing the characteristic morphology of soot [grape-like, "aciniform" clusters of 0.03 μm spheroids]. Presumably this carbon came from major fires of forests or fossil carbon that were ignited by the impact.Extending the earlier SEM study, we have examined several samples by TEM. All samples were isolated by dissolving inorganic minerals with HCI and HF and removing extractable organics and most of the kerogen with organic solvents and NaOH. Fig. 1 shows a sample from the K-T boundary at Woodside Creek, New Zealand. The aciniform carbon is still covered with films of kerogen. Further extractions eventually yield the material in Fig. 2, which is free of kerogen, and shows the delicate, welded structure of soot
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Ke, Yutian, Damien Calmels, Julien Bouchez, and Cécile Quantin. "MOdern River archivEs of Particulate Organic Carbon: MOREPOC." Earth System Science Data 14, no. 10 (October 28, 2022): 4743–55. http://dx.doi.org/10.5194/essd-14-4743-2022.
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Abstract. Riverine transport of particulate organic carbon (POC) associated with terrigenous solids to the ocean has an important role in the global carbon cycle. To advance our understanding of the source, transport, and fate of fluvial POC from regional to global scales, databases of riverine POC are needed, including elemental and isotope composition data from contrasted river basins in terms of geomorphology, lithology, climate, and anthropogenic pressure. Here, we present a new, open-access, georeferenced, and global database called MOdern River archivEs of Particulate Organic Carbon (MOREPOC) version 1.1, featuring data on POC in suspended particulate matter (SPM) collected at 233 locations across 121 major river systems. This database includes 3546 SPM data entries, among them 3053 with POC content, 3402 with stable carbon isotope (δ13C) values, 2283 with radiocarbon activity (Δ14C) values, 1936 with total nitrogen content, and 299 with an aluminum-to-silicon ratio (Al / Si). The MOREPOC database aims at being used by the Earth system community to build comprehensive and quantitative models for the mobilization, alteration, and fate of terrestrial POC. The database is made available on the Zenodo repository in machine-readable formats as a data table and GIS shapefile at https://doi.org/10.5281/zenodo.7055970 (Ke et al., 2022).
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Nugrahadi, Mochamad Saleh, Tetsuo Yanagi, I. G. Tejakusuma, Seno Adi, and Rahmania A. Darmawan. "DISSOLVED AND PARTICULATE CARBON IN JAKARTA BAY, INDONESIA." Marine Research in Indonesia 34, no. 1 (June 30, 2009): 11–16. http://dx.doi.org/10.14203/mri.v34i1.517.
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In order to investigate spatial and temporal variability of dissolved organic carbon (DOC) and particulate organic carbon (POC), several samples were collected from five estuaries, inner part and outer part of Jakarta Bay. The samples were collected on 15 and 16 February 2007, a week after heavy flood in Jakarta Area, and on 16 May 2007. DOC concentration in February and May in Jakarta Bay ranged between 100-950 µg-C/l and between 0-850 µg-C/l respectively. POC concentrations ranged between 50-650 µg-C /l and 50-900 µg-C /1 in February and May 2007, respectively. Even though the concentrations between both periods were similar, the load of organic carbon from the land to Jakarta Bay showed a large contrast due to the different amount of freshwater input. The Total organic carbon fluxes from the rivers to the bay in February and May 2007 were 107.6 t d-' C-(ton per day Carbon) and 42.7 t d-1 C, respectively.
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Basler, A., M. Dippold, M. Helfrich, and J. Dyckmans. "Microbial carbon recycling: an underestimated process controlling soil carbon dynamics." Biogeosciences Discussions 12, no. 13 (July 1, 2015): 9729–50. http://dx.doi.org/10.5194/bgd-12-9729-2015.
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Abstract. The mean residence times (MRT) of different compound classes of soil organic matter (SOM) do not match their inherent recalcitrance to decomposition. One reason for this is the stabilisation within the soil matrix, but recycling, i.e. the reuse of "old" organic material to form new biomass may also play a role as it uncouples the residence times of organic matter from the lifetime of discrete molecules in soil. We analysed soil sugar dynamics in a natural 30 years old labelling experiment after a~wheat-maize vegetation change to determine the extent of recycling and stabilisation in plant and microbial derived sugars: while plant derived sugars are only affected by stabilisation processes, microbial sugars may be subject to both, stabilisation and recycling. To disentangle the dynamics of soil sugars, we separated different density fractions (free particulate organic matter (fPOM), light occluded particulate organic matter (≤1.6 g cm−3; oPOM1.6), dense occluded particulate organic matter (≤2 g cm−3; oPOM2) and mineral-associated organic matter (>2 g cm−3; Mineral)) of a~silty loam under long term wheat and maize cultivation. The isotopic signature of sugars was measured by high pressure liquid chromatography coupled to isotope ratio mass spectrometry (HPLC/IRMS), after hydrolysis with 4 M Trifluoroacetic acid (TFA). While apparent mean residence times (MRT) of sugars were comparable to total organic carbon in the bulk soil and mineral fraction, the apparent MRT of sugars in the oPOM fractions were considerably lower than those of the total carbon of these fractions. This indicates that oPOM formation was fuelled by microbial activity feeding on new plant input. In the bulk soil, mean residence times of the mainly plant derived xylose (xyl) were significantly lower than those of mainly microbial derived sugars like galactose (gal), rhamnose (rha), fucose (fuc), indicating that recycling of organic matter is an important factor regulating organic matter dynamics in soil.
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Fisher, Thomas R., James D. Hagy, and Emma Rochelle-Newall. "Dissolved and Particulate Organic Carbon in Chesapeake Bay." Estuaries 21, no. 2 (June 1998): 215. http://dx.doi.org/10.2307/1352470.
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Zhu, Z. Y., Y. Wu, S. M. Liu, F. Wenger, J. Hu, J. Zhang, and R. F. Zhang. "Particulate organic matter composition and organic carbon flux in Arctic valley glaciers: examples from the Bayelva River and adjacent Kongsfjorden." Biogeosciences Discussions 12, no. 18 (September 22, 2015): 15655–85. http://dx.doi.org/10.5194/bgd-12-15655-2015.
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Abstract. In the face of ongoing global warming and glacier retreat, the composition and flux of organic matter in glacier–fjord systems are key variables for updating the carbon cycle and budget, whereas the role of Arctic valley glaciers seems unimportant when compared with the huge Greenland Ice Sheet. Our field observations of the glacier-fed Bayelva River, Svalbard, and the adjacent Kongsfjorden allowed us to determine the compositions of particulate organic matter from glacier to fjord and also to estimate the flux of organic carbon, both for the river and for Svalbard in general. Particulate organic carbon (POC) and dissolved organic carbon (DOC) in the Bayelva River averaged 56 and 73 μM, respectively, in August 2012. Amino acids (AAs) and phytoplankton pigments accounted for ~ 10 % of the particulate organic matter (POM) in the Bayelva River, while AAs represented > 90 % of particulate nitrogen in fjord surface water, suggesting the strong in situ assimilation of organic matter. Bacteria accounts for 13 and 19 % of the POC in the Bayelva River and the Kongsfjorden, respectively, while values for particulate nitrogen (PN) are much higher (i.e., 36 % in Kongsfjorden). The total discharge from the Bayelva River in 2012 was 29 × 106 m3. Furthermore, we calculated the annual POC, DOC, and PN fluxes for the river as 20 ± 1.6, 25 ± 5.6, and 4.7 ± 0.75 t, respectively. Using the POC content and DOC concentration data, we then estimated the annual POC and DOC fluxes for Svalbard glaciers. Although the estimated POC (0.056 ± 0.02 × 106 t yr−1) and DOC (0.02 ± 0.01 × 106 t yr−1) fluxes of Svalbard glaciers are small compared with those of the Greenland Ice Sheet, the area-weighted POC flux of Svalbard glaciers is twice that of the Greenland Ice Sheet, while the flux of DOC can be 4 to 7 times higher. Therefore, we propose that valley glaciers are efficient high-latitude sources of organic carbon.
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Dhargalkar, Vinod K., and Narayan B. Bhosle. "Particulate organic matter in shelf waters of Prinsesse Astrid Kyst, Antarctica." Polar Record 25, no. 154 (July 1989): 229–34. http://dx.doi.org/10.1017/s0032247400010846.
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AbstractParticulate matter collected at a single station in waters off the ice shelf of Prinsesse Astrid Kyst (70°S, 11°E), Antarctica, during the austral summer January–February 1986 was analyzed for organic content. Phytoplankton biomass represented by chlorophyll α varied from 0.051 to 3.1 μg dm-3. Values for constituent fractions ranged as follows: adenosine triphosphate 0.33 to 1.81 μg dm-3, particulate organic carbon 305 to 1850 μg dm-3, particulate carbohydrates 8 to 176 μg dm-3, particulate proteins 22 to 132 μg dm-3 and particulate lipids 8 to 209 μg dm-3. Large variation in values suggested patchy distribution. The likely presence of degraded carbon argues in favour of an active microbial community in these waters
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IWATA, BRUNA DE FREITAS, MARIA LETÍCIA STEFANY MONTEIRO BRANDÃO, REGIS DOS SANTOS BRAZ, LUIZ FERNANDO CARVALHO LEITE, and MIRIAN CRISTINA GOMES COSTA. "TOTAL AND PARTICULATE CONTENTS AND VERTICAL STRATIFICATION OF ORGANIC CARBON IN AGROFORESTRY SYSTEM IN CAATINGA." Revista Caatinga 34, no. 2 (June 2021): 443–51. http://dx.doi.org/10.1590/1983-21252021v34n220rc.
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ABSTRACT The objective of this work was to evaluate the variation in total and particulate organic carbon contents, carbon vertical stratification, and sensitivity index of organic matter fractions in soils with organic residues arranged in alleys in an agroforestry system, with and without use of fire, in the Caatinga biome, in Brazil. The experiment was conducted in a split-plot arrangement with four replications, with the factor fire in the plots, and the factor organic residues in the subplots. The organic residues used consisted of Gliricidia sepium plants; G. sepium plants and carnauba processing residue; G. sepium plants and bio-compost; and G. sepium plants, carnauba processing residue, and bio-compost, which were evaluated in three soil layers. The alleys with carnauba processing residue, G. sepium plants, and bio-compost presented a better maintenance of particulate, and mineral-associated organic carbon contents. Thus, the agroforestry management in alleys using these three residues was efficient for the maintenance of labile and recalcitrant organic matter compartments. Particulate organic carbon was more sensitive to changes in soil management than total organic matter content, in all alleys, presenting higher sensitivity indexes.
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Simonsson, Magnus, Holger Kirchmann, Jakob Magid, and Thomas Kätterer. "Can Particulate Organic Matter Reveal Emerging Changes in Soil Organic Carbon?" Soil Science Society of America Journal 78, no. 4 (June 30, 2014): 1279–90. http://dx.doi.org/10.2136/sssaj2013.12.0533.
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Yu, X. Y., R. A. Cary, and N. S. Laulainen. "Primary and secondary organic carbon downwind of Mexico City." Atmospheric Chemistry and Physics Discussions 9, no. 1 (January 8, 2009): 541–93. http://dx.doi.org/10.5194/acpd-9-541-2009.
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Abstract. In order to study particulate matter transport and transformation in the Megacity environment, fine particulate carbons were measured simultaneously at two supersites, suburban T1 and rural T2, downwind of Mexico City during the MILAGRO field campaign in March 2006. Organic carbon (OC), element carbon (EC), and total carbon (TC=OC+EC) were determined in near real-time using a Sunset semi-continuous OC/EC field analyzer. The semi-empirical EC tracer method was used to derive primary organic carbon (POC) and secondary organic carbon (SOC). Diurnal variations of primary and secondary carbons were observed at T1 and T2, which resulted from boundary layer inversion and impacted by local traffic patterns. The majority of organic carbon particles at T1 and T2 were secondary. The SOC% (SOC%=SOC/TC×100%) at T1 ranged from 1.2–100% with an average of 80.7±14.4%. The SOC% at T2 ranged from 12.8–100% with an average of 80.1±14.0%. The average EC to PM2.5 percentage (ECPM%=EC/PM2.5×100%) and OCPM% were 6.0% and 20.0% over the whole sampling time at T1. The POC to PM percentage (POCPM%) and SOCPM% were 3.7% and 16.3%, respectively at the same site. The maximum ECPM% was 21.2%, and the maximum OCPM% was 57.2% at T1. The maximum POCPM% was 12.9%, and the maximum SOCPM% was 49.7% at the suburban site. Comparison of SOC and POC at T1 and T2 showed similar characteristics under favorable meteorological conditions, which indicated that transport between the two supersites took place. Strong correlations between EC and carbon monoxide (CO) and odd nitrogen species (NO and NOx) were observed at T1. This indicated that EC had nearby sources, such as local traffic emissions. The EC/CO ratio derived by linear regression analysis, when parameters in μg C/m3 and μg/m3, respectively, was 0.0045 at T1. Correlations were also seen between OC and SOC vs. the sum of oxidants, such as O3 and NO2, suggesting the secondary nature of carbons observed at T1.
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Charron, A., C. Degrendele, B. Laongsri, and R. M. Harrison. "Receptor modelling of secondary particulate matter at UK sites." Atmospheric Chemistry and Physics Discussions 12, no. 10 (October 17, 2012): 27255–95. http://dx.doi.org/10.5194/acpd-12-27255-2012.
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Abstract. Complementary approaches have been taken to better understand the sources and their spatial distribution for secondary inorganic (nitrate and sulphate) and secondary organic aerosol sampled at a rural site (Harwell) in the southern United Kingdom. A concentration field map method was applied to 1581 daily samples of chloride, nitrate and sulphate from 2006 to 2010, and 982 samples for organic carbon and elemental carbon from 2007 to 2010. This revealed a rather similar pattern of sources for nitrate, sulphate and secondary organic carbon within western/central Europe, which in the case of nitrate and sulphate, correlated significantly with EMEP emissions maps of NOx and SO2. A slightly more southerly source emphasis for secondary organic carbon may reflect the contribution of biogenic sources. Trajectory clusters confirm this pattern of behaviour with a major contribution from mainland European sources. Similar behaviours of, on the one hand, sulphate and organic carbon and, on the other hand, EC and nitrate showed that the former are more subject to regional influence than the latter in agreement with the slower atmospheric formation of sulphate and secondary organic aerosol than for nitrate, and the local/mesoscale influences upon primary EC. In a separate study, measurements of sulphate, nitrate, elemental and organic carbon were made in 100 simultaneously collected samples at Harwell and at a suburban site in Birmingham (UK). This showed a significant correlation in concentrations between the two sites for all of the secondary constituents, further indicating secondary organic aerosol to be a regional pollutant behaving similarly to sulphate and nitrate.
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Agagliate, Jacopo, Rüdiger Röttgers, Kerstin Heymann, and David McKee. "Estimation of Suspended Matter, Organic Carbon, and Chlorophyll-a Concentrations from Particle Size and Refractive Index Distributions." Applied Sciences 8, no. 12 (December 19, 2018): 2676. http://dx.doi.org/10.3390/app8122676.
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Models of particle density and of organic carbon and chlorophyll-a intraparticle concentration were applied to particle size distributions and particle real refractive index distributions determined from flow cytometry measurements of natural seawater samples from a range of UK coastal waters. The models allowed for the estimation of suspended particulate matter, organic suspended matter, inorganic suspended matter, particulate organic carbon, and chlorophyll-a concentrations. These were then compared with independent measurements of each of these parameters. Particle density models were initially applied to a simple spherical model of particle volume, but generally overestimated independently measured values, sometimes by over two orders of magnitude. However, when the same density models were applied to a fractal model of particle volume, successful agreement was reached for suspended particulate matter and both inorganic and organic suspended matter values (RMS%E: 57.4%, 148.5%, and 83.1% respectively). Non-linear organic carbon and chlorophyll-a volume scaling models were also applied to a spherical model of particle volume, and after an optimization procedure achieved successful agreement with independent measurements of particulate organic carbon and chlorophyll-a concentrations (RMS%E: 45.6% and 51.8% respectively). Refractive index-based models of carbon and chlorophyll-a intraparticle concentration were similarly tested, and were also found to require a fractal model of particle volume to achieve successful agreement with independent measurements, producing RMS%E values of 50.2% and 45.2% respectively after an optimization procedure. It is further shown that the non-linear exponents of the volume scaling models are mathematically equivalent to the fractal dimensionality coefficients that link cell volume to mass concentration, reflecting the impact of non-uniform distribution of intracellular carbon within cells. Fractal models of particle volume are thus found to be essential to successful closure between results provided by models of particle mass, intraparticle carbon and chlorophyll content, and bulk measurements of suspended mass and total particulate carbon and chlorophyll when natural mixed particle populations are concerned. The results also further confirm the value of determining both size and refractive index distributions of natural particle populations using flow cytometry.
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Janning, K. F., X. Le Tallec, and P. Harremoës. "Hydrolysis of organic wastewater particles in laboratory scale and pilot scale biofilm reactors under anoxic and aerobic conditions." Water Science and Technology 38, no. 8-9 (October 1, 1998): 179–88. http://dx.doi.org/10.2166/wst.1998.0805.
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Hydrolysis and degradation of particulate organic matter has been isolated and investigated in laboratory scale and pilot scale biofilters. Wastewater was supplied to biofilm reactors in order to accumulate particulates from wastewater in the filter. When synthetic wastewater with no organic matter was supplied to the reactors, hydrolysis of the particulates was the only process occurring. Results from the laboratory scale experiments under aerobic conditions with pre-settled wastewater show that the initial removal rate is high: rV, O2 = 2.1 kg O2/(m3 d) though fast declining towards a much slower rate. A mass balance of carbon (TOC/TIC) shows that only 10% of the accumulated TOC was transformed to TIC during the 12 hour long experiment. The pilot scale hydrolysis experiment was performed in a new type of biofilm reactor - the B2A® biofilter that is characterised by a series of decreasing sized granular media (80-2.5 mm). When hydrolysis experiments were performed on the anoxic pilot biofilter with pre-screened wastewater particulates as carbon source, a rapid (rV, NO3=0.7 kg NO3-N/(m3 d)) and a slowler (rV, NO3 = 0.3 kg NO3-N/(m3 d)) removal rate were observed at an oxygen concentration of 3.5 mg O2/l. It was found that the pilot biofilter could retain significant amounts of particulate organic matter, reducing the porosity of the filter media of an average from 0.35 to 0.11. A mass balance of carbon shows that up to 40% of the total incoming TOC accumulates in the filter at high flow rates. Only up to 15% of the accumulated TOC was transformed to TIC during the 24 hour long experiment.
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Golchin, A., JM Oades, JO Skjemstad, and P. Clarke. "Soil structure and carbon cycling." Soil Research 32, no. 5 (1994): 1043. http://dx.doi.org/10.1071/sr9941043.
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Samples from the surface horizons of six virgin soils were collected and separated into density fractions. Based on the spatial distribution of organic materials within the mineral matrix of soil, the soil organic matter (SOM) contained in various density fractions was classified as: (a) free particulate OM, (b) occluded particulate OM, and (c) colloidal or clay-associated OM. The compositional differences noted among these three components of SOM were used to describe the changes that OM undergoes during decomposition when it enters the soil, is enveloped in aggregates and eventually is incorporated into microbial biomass and metabolites and associated with clay minerals. The occluded organic materials, released as a result of aggregate disruption, were in various stages of decomposition and had different degrees of association with mineral particles. Changes in the degree of association of occluded organic materials and mineral particles with decomposition are discussed and form the basis of a model which illustrates the simultaneous dynamics of microaggregates and their organic cores. This model indicates a major role for carbohydrate-rich plant debris in formation and stabilization of microaggregates.
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Golchin, A., JM Oades, JO Skjemstad, and P. Clarke. "Structural and dynamic properties of soil organic-matter as reflected by 13C natural-abundance, pyrolysis mass-spectrometry and solid-state 13C NMR-spectroscopy in density fractions of an oxisol under forest and pasture." Soil Research 33, no. 1 (1995): 59. http://dx.doi.org/10.1071/sr9950059.
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Changes in the content and isotopic composition of organic carbon as a consequence of deforestation and pasture establishment were studied in three neighbouring areas on an Oxisol from Australia and used to measure the turnover of forest-derived carbon (C3) under pasture (C4) over 35 and 83 year time scales. The results indicated that the quantity of forest-derived carbon declined rapidly during the first 35 years under pasture but the content remained nearly stable thereafter, suggesting the presence of two pools of carbon with different turnover times. The calculated values for turnover time of labile and resistant fractions of forest-derived carbon were 35 and 144 years respectively. The soil samples were separated into five fractions with densities <1.6 (free and occluded), 1.6-1.8, 1.8-2.0 and >2.0 Mg m-3. Based on the spatial distribution of organic materials within the mineral matrix of soil, the soil organic matter contained in different density fractions was classified as free particulate organic matter (1.6 free), occluded particulate organic matter (<1.6 occluded, 1.6-1.8 and 1.8-2.0) and clay associated organic matter (>2.0 Mg m-3). The 13C natural abundance showed that the free particulate organic matter formed a significant pool for soil organic matter turnover when the forest was replaced by pasture. Compared with free particulate organic matter, the organic materials occluded within aggregates had slower turnover times. The occluded organic materials were in different stages of decomposition and had different chemical stabilities. Comparison of the chemistry and isotopic composition of occluded organic materials indicated that the O-alkyl C content of the occluded organic materials was inversely related to their stabilities whereas their aromatic C content was directly related to their stabilities. In soils under pasture, a considerable amount of forest-derived carbon was associated with clay particles in the fractions .2.0 Mg m-3. The rate of accumulation of pasture-derived carbon was also rapid in this fraction, indicating the presence of two different pools of carbon (C3 and C4) associated with clay particles. The forest-derived carbon had the highest stability in the fractions >2.0 Mg m-3, probably due to strong interaction with active aluminium or iron and aluminium oxides associated with clay surfaces.
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Pavia, Frank J., Robert F. Anderson, Phoebe J. Lam, B. B. Cael, Sebastian M. Vivancos, Martin Q. Fleisher, Yanbin Lu, Pu Zhang, Hai Cheng, and R. Lawrence Edwards. "Shallow particulate organic carbon regeneration in the South Pacific Ocean." Proceedings of the National Academy of Sciences 116, no. 20 (April 29, 2019): 9753–58. http://dx.doi.org/10.1073/pnas.1901863116.
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Particulate organic carbon (POC) produced in the surface ocean sinks through the water column and is respired at depth, acting as a primary vector sequestering carbon in the abyssal ocean. Atmospheric carbon dioxide levels are sensitive to the length (depth) scale over which respiration converts POC back to inorganic carbon, because shallower waters exchange with the atmosphere more rapidly than deeper ones. However, estimates of this carbon regeneration length scale and its spatiotemporal variability are limited, hindering the ability to characterize its sensitivity to environmental conditions. Here, we present a zonal section of POC fluxes at high vertical and spatial resolution from the GEOTRACES GP16 transect in the eastern tropical South Pacific, based on normalization to the radiogenic thorium isotope 230Th. We find shallower carbon regeneration length scales than previous estimates for the oligotrophic South Pacific gyre, indicating less efficient carbon transfer to the deep ocean. Carbon regeneration is strongly inhibited within suboxic waters near the Peru coast. Canonical Martin curve power laws inadequately capture POC flux profiles at suboxic stations. We instead fit these profiles using an exponential function with flux preserved at depth, finding shallow regeneration but high POC sequestration below 1,000 m. Both regeneration length scales and POC flux at depth closely track the depths at which oxygen concentrations approach zero. Our findings imply that climate warming will result in reduced ocean carbon storage due to expanding oligotrophic gyres, but opposing effects on ocean carbon storage from expanding suboxic waters will require modeling and future work to disentangle.
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Gehlen, M., L. Bopp, N. Emprin, O. Aumont, C. Heinze, and O. Ragueneau. "Reconciling surface ocean productivity, export fluxes and sediment composition in a global biogeochemical ocean model." Biogeosciences Discussions 3, no. 3 (June 28, 2006): 803–36. http://dx.doi.org/10.5194/bgd-3-803-2006.
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Abstract. This study focuses on an improved representation of the biological soft tissue pump in the global three-dimensional biogeochemical ocean model PISCES. We compare three parameterizations of particle dynamics: (1) the model standard version including two particle size classes, aggregation-disaggregation and prescribed sinking speed; (2) an aggregation-disaggregation model with a particle size spectrum and prognostic sinking speed; (3) a mineral ballast parameterization with no size classes, but prognostic sinking speed. In addition, the model includes a description of surface sediments and organic carbon early diagenesis. The integrated representation of material fluxes from the productive surface ocean down to the sediment-water interface allows taking advantage of surface ocean observations, sediment trap data and exchange fluxes at the sediment-water interface. The capability of the model to reproduce yearly averaged particulate organic carbon fluxes and benthic oxygen demand does at first order not dependent on the resolution of the particle size spectrum. Model results obtained with the standard version and with the one including a particle size spectrum and prognostic sinking speed are not significantly different. Both model versions overestimate particulate organic carbon between 1000 and 2000 m, while deep fluxes are of the correct order of magnitude. Predicted benthic oxygen fluxes correspond with respect to their large scale distribution and magnitude to data based estimates. Modeled particulate organic C fluxes across the mesopelagos are most sensitive to the intensity of zooplankton flux feeding. An increase of the intensity of flux feeding in the standard version results in lower mid- and deep-water particulate organic carbon fluxes, shifting model results to an underestimation of particulate organic carbon fluxes in the deep. The corresponding benthic oxygen fluxes are too low. The model version including the mineral ballast parameterization yields an improved fit between modeled and observed particulate organic carbon fluxes below 2000 m and down to the sediment-water interface. Our results suggest that aggregate formation alone might not be sufficient to drive an intense biological pump. The later is most likely driven by the combined effect of aggregate formation and mineral ballasting.
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Shah, S. R., D. R. Griffith, V. Galy, A. P. McNichol, and T. I. Eglinton. "Prominent bacterial heterotrophy and sources of <sup>13</sup>C-depleted fatty acids to the interior Canada Basin." Biogeosciences Discussions 10, no. 4 (April 11, 2013): 6695–736. http://dx.doi.org/10.5194/bgd-10-6695-2013.
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Abstract. In recent decades, the Canada Basin of the Arctic Ocean has experienced rapidly decreasing summer sea ice coverage and freshening of surface waters. It is unclear how these changes translate to depth, particularly as our baseline understanding of organic carbon cycling in the deep basin is limited. In this study, we describe full-depth profiles of the abundance, distribution and carbon isotopic composition of fatty acids from suspended particulate matter at a seasonally ice-free station and a semi-permanently ice-covered station. Fatty acids, along with suspended particulate organic carbon (POC), are more concentrated under ice cover than in ice-free waters. But this influence, apparent at 50 m depth, does not propagate downward below 150 m depth, likely due to the weak biological pump in the central Canada Basin. Branched fatty acids have δ13C values that are similar to suspended POC at all depths and are 13C-enriched compared to even-numbered saturated fatty acids at depths above 3000 m. These are likely to be produced in situ by heterotrophic bacteria incorporating organic carbon that is isotopically similar to total suspended POC. A source of saturated even-numbered fatty acids is also suggested below surface waters which could represent contributions from laterally advected organic carbon or from chemoautotrophic bacteria. At 3000 m depth and below, a greater relative abundance of long-chain (C20–24), branched and unsaturated fatty acids is consistent with a stronger influence of re-suspended sedimentary organic carbon on benthic particulate matter. At these deep depths, two individual fatty acids (C12 and iso-C17) are significantly depleted in 13C, allowing for the possibility that methane oxidizing bacteria contribute fatty acids, either directly to suspended particulate matter or to shallow sediments that are subsequently mobilized and incorporated into suspended particulate matter within the deep basin.
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Chen, Tzong-Yueh, and Annelie Skoog. "Abiotic Aggregation of Organic Matter in Coastal and Estuarine Waters: Cases in the Eastern Long Island Sound, USA." Water 13, no. 21 (November 2, 2021): 3077. http://dx.doi.org/10.3390/w13213077.
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Organic aggregates, which formed from small particles and dissolved material, were chemically characterized in the Long Island Sound coastal waters. In this study, six aggregation experiments were conducted on low-salinity samples (the Thames River, CT, USA; salinity of 6.3–6.8) and high-salinity samples (the coast of Avery Point, CT, USA; salinity of 21.4–26.7). Water samples were incubated on a roller table for two days under dark conditions to generate laboratory-made aggregates. Particulate organic carbon (POC) concentrations increased 5–39% after two days of rolling. A higher POC increase occurred in low-salinity samples. The concentrations of neutral aldoses and amino acids, as well as their C- and N-yields, decreased during the experiments (except for particulate hydrolysable amino acid in low-salinity samples), while bacterial abundance increased 50–476%, indicating microbial degradation of biologically labile organic matter. Particulate hydrolysable amino acid was preferentially preserved in P-limited systems. An enrichment factor analysis showed the preferential microbial degradation of particulate hydrolysable neutral aldose and glucose appeared as the most labile aldose. The increase in bulk POC and the decrease in the fraction of labile organic carbon (neutral aldose and amino acid) in the particulate phase resulted in an accumulation of uncharacterized (presumably more refractory) particulate organic matter.
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Venkateswaran, K., A. Shimada, A. Maruyama, T. Higashihara, H. Sakou, and T. Maruyama. "Microbial characteristics of Palau Jellyfish Lake." Canadian Journal of Microbiology 39, no. 5 (May 1, 1993): 506–12. http://dx.doi.org/10.1139/m93-072.
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Microbiological examinations of total bacterial population, culturable aerobic heterotrophs, photosynthetic bacteria, and particulate DNA were carried out in Palau Jellyfish Lake. A 2 m thick bacterial plate layer at 13–15 m depth consisting of various components of microbes was observed in Jellyfish Lake. Photosynthetic bacteria, as seen by flow cytometry, were concentrated at 14–15 m depths with a maximal count of 2.2 × 105 cells∙mL−1 and microscopic analysis confirmed that these purple bacteria were Chromatium sp. Peaks in total bacterial counts (8.3 × 106 cells∙mL−1; 13 m), in the Synechococcus spp. population (2.4 × 106 cells∙mL−1; 13 m), in culturable heterotrophs (105 colony-forming units∙mL−1; 15 m), and in particulate DNA (17.8 μg∙L−1; 10 m) were observed either at the bacterial plate layer that was rich in nutrients or just above this layer in the oxic zone. Bacteriochlorophyll and chlorophyll a exhibited peaks at the photosynthetic bacterial plate (14–15 m). A high concentration of particulate organic carbon was also observed at 15 m. The particulate DNA showed a high degree of correlation with the total bacterial cell number. A low ratio of particulate DNA to particulate organic carbon (0.005) in the water column was found at 15 m and suggested that the particulate materials produced by photosynthetic bacteria would have influenced the concentration of particulate organic carbon. Culturable heterotrophs, clustered into nine different groups, were dominated by species of the genera Vibrio, Aeromonas, and Halomonas.Key words: Jellyfish Lake, microbiological characteristics, Chromatium, particulate DNA, heterotrophs.
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Sauzède, R., J. E. Johnson, H. Claustre, G. Camps-Valls, and A. B. Ruescas. "ESTIMATION OF OCEANIC PARTICULATE ORGANIC CARBON WITH MACHINE LEARNING." ISPRS Annals of Photogrammetry, Remote Sensing and Spatial Information Sciences V-2-2020 (August 3, 2020): 949–56. http://dx.doi.org/10.5194/isprs-annals-v-2-2020-949-2020.
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Abstract. Understanding and quantifying ocean carbon sinks of the planet is of paramount relevance in the current scenario of global change. Particulate organic carbon (POC) is a key biogeochemical parameter that helps us characterize export processes of the ocean. Ocean color observations enable the estimation of bio-optical proxies of POC (i.e. particulate backscattering coefficient, bbp) in the surface layer of the ocean quasi-synoptically. In parallel, the Argo program distributes vertical profiles of the physical properties with a global coverage and a high spatio-temporal resolution. Merging satellite ocean color and Argo data using a neural networkbased method has already shown strong potential to infer the vertical distribution of bio-optical properties at global scale with high space-time resolution. This method is trained and validated using a database of concurrent vertical profiles of temperature, salinity, and bio-optical properties, i.e. bbp, collected by Biogeochemical-Argo (BGC-Argo) floats, matched up with satellite ocean color products. The present study aims at improving this method by 1) using a larger dataset from BGC-Argo network since 2016 for training, 2) using additional inputs such as altimetry data, which provide significant information on mesoscale processes impacting the vertical distribution of bbp, 3) improving the vertical resolution of estimation, and 4) examining the potential of alternative machine learning-based techniques. As a first attempt with the new data, we used some feature-specific preprocessing routines followed by a Multi-Output Random Forest algorithm on two regions with different ocean dynamics: North Atlantic and Subtropical Gyres. The statistics and the bbp profiles obtained from the validation floats show promising results and suggest this direction is worth investigating even further at global scale.
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Rosenheim, Brad E., and Valier Galy. "Direct measurement of riverine particulate organic carbon age structure." Geophysical Research Letters 39, no. 19 (October 3, 2012): n/a. http://dx.doi.org/10.1029/2012gl052883.
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Bertoni, Roberto. "Size distribution of particulate organic carbon in Lago Maggiore." SIL Proceedings, 1922-2010 27, no. 5 (December 2000): 2836–39. http://dx.doi.org/10.1080/03680770.1998.11898185.
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Adams, Jessica L., Edward Tipping, Charlotte L. Bryant, Rachel C. Helliwell, Hannah Toberman, and John Quinton. "Aged riverine particulate organic carbon in four UK catchments." Science of The Total Environment 536 (December 2015): 648–54. http://dx.doi.org/10.1016/j.scitotenv.2015.06.141.
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Gardner, Wilford D., Mary Jo Richardson, Craig A. Carlson, Dennis Hansell, and Alexey V. Mishonov. "Determining true particulate organic carbon: bottles, pumps and methodologies." Deep Sea Research Part II: Topical Studies in Oceanography 50, no. 3-4 (March 2003): 655–74. http://dx.doi.org/10.1016/s0967-0645(02)00589-1.
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Simbo, Richard Tamba, Maria Fe Rebecca D. Gueta, Tokunbo Abel Oladejo, and Taoheed Olawale Bello. "Organic Carbon Speciation in Settling Particulate Matter and Sediments." Open Journal of Applied Sciences 12, no. 11 (2022): 1730–39. http://dx.doi.org/10.4236/ojapps.2022.1211118.
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Pulido-Villena, Elvira, Isabel Reche, and Rafael Morales-Baquero. "Food web reliance on allochthonous carbon in two high mountain lakes with contrasting catchments: a stable isotope approach." Canadian Journal of Fisheries and Aquatic Sciences 62, no. 11 (November 1, 2005): 2640–48. http://dx.doi.org/10.1139/f05-169.
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The carbon isotopic signature (δ13C) of dissolved inorganic carbon and food web components was examined in two high mountain lakes. Río Seco Lake is partially surrounded by alpine meadows and has temporal inlets, whereas La Caldera Lake is located on rocky terrain and does not receive inputs from runoff. We assessed whether these contrasting catchments involve differences in the isotopic signature of the food web components and then in the reliance on terrestrial carbon. The δ13C of dissolved inorganic carbon was not significantly different between lakes and reflected an atmospheric gas exchange origin. Unexpectedly, bulk particulate organic matter showed enriched δ13C values in both lakes, suggesting a terrestrial vegetation influence. Bulk particulate organic matter was exploited mostly by the cladoceran Daphnia pulicaria, whereas the copepod Mixodiaptomus laciniatus was 13C depleted relative to particulate organic matter, indicating a selective feeding on an isotopically lighter source, likely phytoplankton. The results obtained show that, despite contrasting catchments, the food web of both lakes might be partially supported by terrestrial carbon for which utilization is species specific.
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Knewtson, Sharon J. B., Rhonda Janke, M. B. Kirkham, Kimberly A. Williams, and Edward E. Carey. "Trends in Soil Quality Under High Tunnels." HortScience 45, no. 10 (October 2010): 1534–38. http://dx.doi.org/10.21273/hortsci.45.10.1534.
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Growers have indicated that changes in soil quality under production in high tunnels is an important problem, but these have not yet been quantified or critically assessed in the central Great Plains of the United States. We conducted surveys of grower perceptions of soil quality in their tunnels (n = 81) and compared selected soil quality indicators (salinity and particulate organic matter carbon) under high tunnels of varying ages with those of adjacent fields at sites in Kansas, Missouri, Nebraska, and Iowa in the United States. Fourteen percent of growers surveyed considered soil quality to be a problem in their high tunnels, and there were significant correlations between grower perceptions of soil quality problems and reported observations of clod formation and surface crusting and to a lesser extent surface mineral deposition. Grower perception of soil quality and grower observation of soil characteristics were not related to high tunnel age. Soil surface salinity was elevated in some high tunnels compared with adjacent fields but was not related to time under the high tunnel. In the soil upper 5 cm, salinity in fields did not exceed 2 dS·m−1 and was less than 2 dS·m−1 under 74% of high tunnels and less than 4 dS·m−1 in 97% of high tunnels. The particulate organic matter carbon fraction was higher in high tunnels than adjacent fields at 73% of locations sampled. Particulate organic matter carbon measured 0.11 to 0.67 g particulate organic matter per g of the total carbon under high tunnels sampled. Particulate organic matter carbon in the soil was also not correlated to age of high tunnel. Soil quality as measured in this study was not negatively impacted by use of high tunnel structures over time.
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Salazar, María Paz, Rafael Villarreal, Luis Alberto Lozano, María Florencia Otero, Nicolás Guillermo Polich, Guido Lautaro Bellora, and Carlos Germán Soracco. "Soil organic carbon." Revista de la Facultad de Agronomía 119, no. 2 (December 7, 2020): 053. http://dx.doi.org/10.24215/16699513e053.
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Soil organic carbon (SOC) is an important factor for soil quality diagnosis. Physical and chemical fractionation of SOC are useful to characterize SOC, because some fractions are more sensitive indicators of the effects of different management practices. The aims of this study were (i) to determine values of SOC and different fractions of SOC at different depths and positions in an Argiudoll of the Argentinian Pampas under NT, and (ii) to determine the relation between physical and chemical fractions of SOC. In an experimental plot located in Chascomús, we determined SOC content, humic acids (HA), fulvic acids (FA), humins, coarse and fine particulate organic carbon (POCc and POCf) and mineral associated organic carbon (MOC), at different depths and in the row and inter-row. The content of SOC and different SOC fractions, as well as the contribution of each fraction to SOC showed a vertical variation. The contribution of HA and POCc (newer and more labile fractions) to SOC was larger in the surface than in deeper layers, while humins’ (older and more recalcitrant fraction) contribution to SOC increased with depth, and the contribution of FA, POCf and MOC to SOC remained relatively constant. There was no effect of row and inter-row in SOC content and composition. FA content was correlated to POCc, HA content to POCc and POCf and humins to MOC.
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Chezganova, E. A., O. S. Efimova, S. A. Sozinov, A. R. Efimova, V. M. Sakharova, A. G. Kutikhin, M. V. Osnova, Z. R. Ismagilov, and E. B. Brusina. "Particulate Matter in a Hospital Environment: as Potential Reservoir for Hospital Strains." Epidemiology and Vaccinal Prevention 18, no. 4 (September 13, 2019): 82–92. http://dx.doi.org/10.31631/2073-3046-2019-18-4-82-92.
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Relevance. For decades, many aspects of aerosol transmission of hospital pathogens have been and remain the subject of scientific debate. Despite fairly detailed studies of the mechanism of microbial aerosols formation, distribution, the role of particulate matter in the formation of antibiotic resistance and multidrug-resistant hospital clones of microorganisms is still unclear. Aim. To investigate physicochemical properties and microbiological diversity of hospital particulate matter. Materials and Methods. Shape and size of particulates was assessed by means of scanning electron microscopy and dynamic light scattering while elemental analysis was performed using energy-dispersive X-ray spectroscopy and high-temperature catalytic oxidation. Microbial profiling was conducted using polymerase chain reaction and Vitek 2 biochemical analyzer. Results. Hospital particulate matter included globular and fibrillary particles consisting of carbon, oxygen, calcium, silicon, aluminium, and sulfur. Intriguingly, microfiber particles had higher oxygen and calcium content along with the lower level of carbon in mineral but not organic component. Differential localisation of silicon and calcium in elemental mapping suggested that hospital particulate matter was composed of aluminosilicate minerals and calcium compounds. Among the microorganisms, we found multidrug-resistant strains Raoultella ornithinolytica, Staphylococcus pseudintermedius, Pantoea spp., Pseudomonas aeruginosa, Enterococcus faecium and additionally Pasteurella canis in hospital particulate matter samples. Conclusions. Particulate matter in the hospital environment might be considered as a potential reservoir for the evolution of antibiotic resistance and multidrug-resistant strains.
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Tserenpil, Shurkhuu, Xing Jung Fan, Atindra Sapkota, Enkhmaa Chinzorig, Jian Zhong Song, and Cong Qiang Liu. "High molecular weight humic-like substances in carboneous aerosol of Ulaanbaatar city." Mongolian Journal of Chemistry 19, no. 45 (December 28, 2018): 5–11. http://dx.doi.org/10.5564/mjc.v19i45.1083.
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Total carbon content of the atmospheric suspended particulate matters consisted of as high as 89-93% organic carbon (OC) in Ulaanbaatar aerosol without showing seasonal variation. However, limited aerosol measurements have been conducted on these OC rich aerosols particularly for high molecular weight constituents. In order to address the gap above, abundance of high molecular weight humic-like substances (HULIS) in total suspended particulates (TSP) from Ulaanbaatar atmospheric aerosol were determined for the first time. HULIS molecular structure was characterised for different seasons using carbon content and UV absorbance measurements coupled with solid phase extraction methods. Although, HULIS contributions to water soluble organic fraction of the winter and summer aerosols were similar HULIS carbon concentration was higher in winter samples (9-37 mg·L-1) than in summer (2-6 mg·L-1). Consequently quantity of aromatic moieties and degree of aromaticity varied between seasons.
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Zuijdgeest, A. L., R. Zurbrügg, N. Blank, R. Fulcri, D. B. Senn, and B. Wehrli. "Seasonal dynamics of carbon and nutrients from two contrasting tropical floodplain systems in the Zambezi River Basin." Biogeosciences Discussions 12, no. 13 (July 9, 2015): 10545–78. http://dx.doi.org/10.5194/bgd-12-10545-2015.
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Abstract. Floodplains are important biogeochemical reactors during fluvial transport of carbon and nutrient species towards the oceans. In the tropics and subtropics pronounced rainfall seasonality results in highly dynamic floodplain biogeochemistry. Massive construction of hydropower dams, however, has significantly altered the hydrography and chemical characteristics of many (sub)tropical rivers. In this study, we compare organic matter and nutrient biogeochemistry of two large, contrasting floodplains in the Zambezi River Basin in Southern Africa, the Barotse Plains and the Kafue Flats. Both systems are of comparable size, but differ in anthropogenic influence: while the Barotse Plains are still relatively pristine, the Kafue Flats are bordered by two hydropower dams. While the Barotse Plains retain particles during the wet season, annual yields of particulate organic carbon and nitrogen are higher than previously reported for the Zambezi and other tropical rivers. Enhanced wet-season runoff adds soil-derived dissolved organic carbon and nitrogen to the Zambezi River, with a corresponding increase in the Barotse Plains. Soil-derived organic matter dominates the particulate phase year-round in the Barotse Plains, and a varying influence of C3- and C4-plant vegetation can be observed throughout the year. In contrast to the Barotse Plains, net export of particulate matter from the Kafue Flats has been observed during the wet season, but over an annual cycle, the Kafue Flats are effectively accumulating dissolved carbon and nutrients. In the Kafue Flats, the runoff-induced increase in dissolved organic carbon and nitrogen concentrations is delayed by the upstream dam operation. The dam reservoir also causes a shift in the source of the particulate organic matter – from soil-derived during the dry season to aquatically produced in the wet season – in the downstream Kafue Flats. Spatial zonation in vegetation and temporal flooding dynamics in the Kafue Flats result in mostly C3-derived particulate organic matter during wet season, and a dominance of C4-derived material during dry season. This pattern results from dam-induced changes in vegetation, as dam construction along the Kafue River has led to encroachment of woody plant species onto the Kafue Flats. The two systems exhibit different flooding dynamics, with a~larger contribution of floodplain-derived water in the Kafue Flats and a stronger peak flow in the Barotse Plains. Differences in the biogeochemistry of the two systems that can be linked to the dams are the timing of the runoff-driven dissolved organic carbon and nitrogen pulses in the wet season and the origin and inputs of particulate organic matter. This study reveals clear effects of dam construction on organic matter and nutrient dynamics on the downstream floodplain. Man-made reservoirs alter the origin of organic matter, and change the timing of precipitation-driven carbon and nitrogen pulses. Environmental assessments of dam impacts should therefore consider changes in water quality.
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Chafiq, Mohamed, Janine Gibert, and Cécile Claret. "Interactions among sediments, organic matter, and microbial activity in the hyporheic zone of an intermittent stream." Canadian Journal of Fisheries and Aquatic Sciences 56, no. 3 (March 1, 1999): 487–95. http://dx.doi.org/10.1139/f98-208.
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Interactions between surface and subsurface water in intermittent streams are poorly understood. We predicted that surface discharge patterns would influence retention and transport of fine sediments and particulate organic matter in a first-order intermittent stream, which in turn would affect microbial activity at different depths in the sediment. We measured sediments, dissolved and particulate organic carbon, and microbial and bacterial biomass and activity at three depths (surface and 20 and 40 cm) over a period spanning low and high flows at five stations on an intermittent stream. Discharge influenced physicochemical and sediment characteristics at the upstream stations with coarse substratum. In the finer sediments of the lower reaches, an active hyporheic microbial assemblage primarily governed sediment and organic dynamics. With decreasing discharge and increasing retention of fine sediments and particulate organic carbon, greater microbial hydrolytic activity in bed-sediments occurred downstream. Dissolved oxygen, organic carbon, fine sediments, microbial biomass, hydrolytic activity, and bacterial biomass declined with depth, and changed over time, apparently in response to varying discharge. We conclude that discharge and substratum particle size may interact to control organic dynamics and hyporheic microbial activity in a 1st order stream.
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Mouw, Colleen B., Audrey Barnett, Galen A. McKinley, Lucas Gloege, and Darren Pilcher. "Global ocean particulate organic carbon flux merged with satellite parameters." Earth System Science Data 8, no. 2 (October 20, 2016): 531–41. http://dx.doi.org/10.5194/essd-8-531-2016.
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Abstract. Particulate organic carbon (POC) flux estimated from POC concentration observations from sediment traps and 234Th are compiled across the global ocean. The compilation includes six time series locations: CARIACO, K2, OSP, BATS, OFP, and HOT. Efficiency of the biological pump of carbon to the deep ocean depends largely on biologically mediated export of carbon from the surface ocean and its remineralization with depth; thus biologically related parameters able to be estimated from satellite observations were merged at the POC observation sites. Satellite parameters include net primary production, percent microplankton, sea surface temperature, photosynthetically active radiation, diffuse attenuation coefficient at 490 nm, euphotic zone depth, and climatological mixed layer depth. Of the observations across the globe, 85 % are concentrated in the Northern Hemisphere with 44 % of the data record overlapping the satellite record. Time series sites accounted for 36 % of the data, while 71 % of the data are measured at ≥ 500 m with the most common deployment depths between 1000 and 1500 m. This data set is valuable for investigations of CO2 drawdown, carbon export, remineralization, and sequestration. The compiled data can be freely accessed at doi:10.1594/PANGAEA.855600.
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Guyennon, A., M. Baklouti, F. Diaz, J. Palmieri, J. Beuvier, C. Lebaupin-Brossier, T. Arsouze, K. Béranger, J. C. Dutay, and T. Moutin. "New insights into the organic carbon export in the Mediterranean Sea from 3-D modeling." Biogeosciences Discussions 12, no. 8 (April 24, 2015): 6147–213. http://dx.doi.org/10.5194/bgd-12-6147-2015.
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Abstract. The Mediterranean Sea is one of the most oligotrophic regions of the oceans, and nutrients have been shown to limit both phytoplankton and bacterial activities. This has direct implications on the stock of dissolved organic carbon (DOC), whose high variability has already been well-documented even if measurements are still sparse and are associated with important uncertainties. We here propose a Mediterranean Basin-scale view of the export of organic carbon, under its dissolved and particulate forms. For this purpose, we have used a coupled model combining a mechanistic biogeochemical model (Eco3M-MED) and a high-resolution (eddy-resolving) hydrodynamic simulation (NEMO-MED12). This is the first Basin-scale application of the biogeochemical model Eco3M-MED and is shown to reproduce the main spatial and seasonal biogeochemical characteristics of the Mediterranean Sea. Model estimations of carbon export are of the same order of magnitude as estimations from in situ observations, and their respective spatial patterns are consistent with each other. As for surface chlorophyll, nutrient concentrations, and productivity, strong differences between the Western and Eastern Basins are evidenced by the model for organic carbon export, with only 39% of organic carbon (particulate and dissolved) export taking place in the Western Basin. The major result is that except for the Alboran Sea, dissolved organic carbon (DOC) contribution to organic carbon export is higher than that of particulate (POC) in the whole Basin, especially in the Eastern Basin. This paper also investigates the seasonality of DOC and POC exports as well as the differences in the processes involved in DOC and POC exports.
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Zuijdgeest, A. L., R. Zurbrügg, N. Blank, R. Fulcri, D. B. Senn, and B. Wehrli. "Seasonal dynamics of carbon and nutrients from two contrasting tropical floodplain systems in the Zambezi River basin." Biogeosciences 12, no. 24 (December 21, 2015): 7535–47. http://dx.doi.org/10.5194/bg-12-7535-2015.
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Abstract. Floodplains are important biogeochemical reactors during fluvial transport of carbon and nutrient species towards the oceans. In the tropics and subtropics, pronounced rainfall seasonality results in highly dynamic floodplain biogeochemistry. The massive construction of dams, however, has significantly altered the hydrography and chemical characteristics of many (sub)tropical rivers. In this study, we compare organic-matter and nutrient biogeochemistry of two large, contrasting floodplains in the Zambezi River basin in southern Africa: the Barotse Plains and the Kafue Flats. Both systems are of comparable size but differ in anthropogenic influence: while the Barotse Plains are still in large parts pristine, the Kafue Flats are bordered by two hydropower dams. The two systems exhibit different flooding dynamics, with a larger contribution of floodplain-derived water in the Kafue Flats and a stronger peak flow in the Barotse Plains. Distinct seasonal differences have been observed in carbon and nutrient concentrations, loads, and export and retention behavior in both systems. The simultaneous retention of particulate carbon and nitrogen and the net export of dissolved organic and inorganic carbon and nitrogen suggested that degradation of particulate organic matter was the dominant process influencing the river biogeochemistry during the wet season in the Barotse Plains and during the dry season in the Kafue Flats. Reverse trends during the dry season indicated that primary production was important in the Barotse Plains, whereas the Kafue Flats seemed to have both primary production and respiration occurring during the wet season, potentially occurring spatially separated in the main channel and on the floodplain. Carbon-to-nitrogen ratios of particulate organic matter showed that soil-derived material was dominant year-round in the Barotse Plains, whereas the Kafue Flats transported particulate organic matter that had been produced in the upstream reservoir during the wet season. Stable carbon isotopes suggested that inputs from the inundated floodplain to the particulate organic-matter pool were important during the wet season, whereas permanent vegetation contributed to the material transported during the dry season. This study revealed effects of dam construction on organic-matter and nutrient dynamics on the downstream floodplain that only become visible after longer periods, and it highlights how floodplains act as large biogeochemical reactors that can behave distinctly differently from the entire catchment.
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Kirchstetter, T. W., and T. L. Thatcher. "Contribution of organic carbon to wood smoke particulate matter absorption of solar radiation." Atmospheric Chemistry and Physics Discussions 12, no. 2 (February 23, 2012): 5803–16. http://dx.doi.org/10.5194/acpd-12-5803-2012.
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Abstract. Spectroscopic analysis shows that 115 residential wood smoke-dominated particulate matter samples absorb light with strong spectral selectivity, consistent with prior work that has demonstrated that organic carbon (OC), in addition to black carbon (BC), appreciably absorbs solar radiation in the visible and ultraviolet spectral regions. Apportionment of light absorption yields the absorption Ångström exponent of the light absorbing OC in these samples, which ranges from 3.0 to 7.4 and averages 5.0, and indicates that OC and BC, respectively, would account for 14% and 86% of solar radiation absorbed by the wood smoke in the atmosphere (integrated over the solar spectrum from 300 to 2500 nm). OC would contribute 49% of the wood smoke particulate matter absorption of ultraviolet solar radiation at wavelengths below 400 nm. These results illustrate that BC is the dominant light absorbing particulate matter species in atmospheres burdened with residential wood smoke and OC absorption is secondary but not insignificant. Further, since biomass combustion generates a major portion of atmospheric particulate matter globally, these results suggest that OC absorption should be included when particulate matter effects on the radiative forcing of climate are considered, and that OC absorption may affect the ultraviolet actinic flux and thus tropospheric photochemistry.
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Toro Araya, Richard, Robert Flocchini, Rául G. E. Morales Segura, and Manuel A. Leiva Guzmán. "Carbonaceous Aerosols in Fine Particulate Matter of Santiago Metropolitan Area, Chile." Scientific World Journal 2014 (2014): 1–12. http://dx.doi.org/10.1155/2014/794590.
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Measurements of carbonaceous aerosols in South American cities are limited, and most existing data are of short term and limited to only a few locations. For 6 years (2002–2007), concentrations of fine particulate matter and organic and elemental carbon were measured continuously in the capital of Chile. The contribution of carbonaceous aerosols to the primary and secondary fractions was estimated at three different sampling sites and in the warm and cool seasons. The results demonstrate that there are significant differences in the levels in both the cold (March to August) and warm (September to February) seasons at all sites studied. The percent contribution of total carbonaceous aerosol fine particulate matter was greater in the cool season (53 ± 41%) than in the warm season (44 ± 18%). On average, the secondary organic carbon in the city corresponded to 29% of the total organic carbon. In cold periods, this proportion may reach an average of 38%. A comparison of the results with the air quality standards for fine particulate matter indicates that the total carbonaceous fraction alone exceeds the World Health Organization standard (10 µg/m3) and the United States Environmental Protection Agency standard (15 µg/m3) for fine particulate matter.
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Schwenke, G. D., M. K. McLeod, S. R. Murphy, S. Harden, A. L. Cowie, and V. E. Lonergan. "The potential for sown tropical perennial grass pastures to improve soil organic carbon in the North-West Slopes and Plains of New South Wales." Soil Research 51, no. 8 (2013): 726. http://dx.doi.org/10.1071/sr13200.
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Sown tropical perennial grass pastures may be a means to restore soil organic carbon (C) lost by cropping with conventional tillage to the levels originally present in native grass pastures. To assess this, total organic carbon and related soil properties were measured under sown tropical pastures, conventionally cultivated cropping, and native pastures on 75 Chromosols and 70 Vertosols to 0.3 m depth in the New South Wales North-West Slopes and Plains region of Australia. The impact of several perennial pasture species on soil organic carbon was also assessed in a 6-year-old, sown pasture experiment on a previously cropped Chromosol. Soil cores in 0.1-m segments to 0.3 m were analysed for total organic carbon, total nitrogen (N), pH, and phosphorus (Colwell-P). Mid-infrared scans were used to predict the particulate, humus, and resistant fractions of the total organic carbon. Bulk density was used to calculate stocks of C, N, and C fractions. In Chromosols, total organic carbon in the surface 0–0.1 m was greater under sown tropical pastures (23.1 Mg ha–1) than conventional tillage cropping (17.7 Mg ha–1), but still less than under native pastures (26.3 Mg ha–1). Similar land-use differences were seen for particulate and resistant organic C, and total N. The proportional differences between land uses were much greater for particulate organic C than other measures, and were also significant at 0.1–0.2 and 0.2–0.3 m. Subsurface bulk density (0.1–0.2 m) was lower under sown tropical pastures (1.42 Mg m–3) than conventionally tilled cropping (1.52 Mg m–3). For Vertosols, total organic carbon in the surface 0–0.1 m was greater under sown tropical pastures (19.0 Mg ha–1) and native pastures (20.5 Mg ha–1) than conventional tillage cropping (14.0 Mg ha–1). Similar land-use effects were seen for the particulate and humus organic C fractions, and total N. In the sown pasture species experiment, there was no significant difference in total N, total organic carbon, or any C fraction between soils under a native-grass species mixture, two improved tropical grass species, or a perennial pasture legume. Regular monitoring is required to better discern whether gradual changes are being masked by spatial and temporal variation. The survey results support previous research on Vertosols within the New South Wales North-West Slopes and Plains that show sown tropical grass pastures can improve total organic carbon. Improvements in total organic carbon on Chromosols have not previously been documented, so further targeted soil monitoring and experimentation is warranted for the region.