Global ETD Search
Search theses and dissertations gathered from participating repositories worldwide. Every result links back to the library that holds it. No account is needed.
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Showing 1 to 20 of 57 for “"particulate organic carbon"”.
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Photochemical transformation of particulate organic carbon and its impact on mercury cycling in aqueous systems
… is known to strongly associate with natural organic matter (NOM), which, in turn, affects its speciation, solubility, mobility and toxicity. Numerous studies have examined Hg coordination with dissolved organic carbon (DOC), an important aqueous constituent that alters the reactivity and fate …
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Particulate organic carbon and mineral export from the North and South Atlantic gyres : the 234Th/238U disequilibrium approach.
… ocean gyres are typically characterised by low carbon export into the deep ocean. However, due to their large area, even relatively small average carbon export may be globally significant. Strong correlations observed between deep-sea organic carbon, calcite and opal suggest that mineral phases …
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Quantifying Rates of Autocompaction in the Pearl River Marsh, Louisiana
… 210Pb, and sedimentary variables, specifically, particulate organic carbon, bulk density, median grain size, porosity, and water content. An upper and an underlying sedimentary unit (named the 137Cs and 210Pb units) were defined between radiometric datum levels, and their sedimentary properties …
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Phytoplankton Dynamics in the Very Low Salinity Region of the James River Estuary, Virginia, U.S.A.
… of dissolved silicate, relatively high ratio of particulate biogenic silica to particulate organic carbon, and relatively low ratio of particulate organic carbon to chlorophyll a in the very low salinity region indicate that diatoms are selectively trapped within this zone.</p> <p>As river …
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Seasonal variability of sediment oxygen demand and biogeochemistry on the Namibian inner shelf
… system. Local biogeochemical remineralization of organic matter mostly related to the primary production in surface waters (Chapman and Shannon, 1985) is thought to drive seasonal variability in sediment oxygen demand. New understanding of the system suggests that shelf hypoxia is driven by a …
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The Role of Autochothnous Production in the Formation of Dissolved and Particulate Organics in Laboratory Streams
… in the formation of dissolved and fine particulate organic carbon (DOC and FPOC) was studied in simplified communities in six laboratory streams. Production of DOC and FPOC by laboratory stream communities exposed to low (170 ft-c), intermediate (260 ft-c), and high (450 ft-c) light …
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Factors Shaping Macrofaunal Polychaete Communities in the Gulf of Mexico
… ranges were examined. Depth, export flux of particulate organic carbon (POC), percent sand and silt were the best predictors of heterogeneity of polychaetes in the GoM. We performed an ecological niche modeling analysis (ENM) based on ?presence-only? data of four cosmopolitan species …
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Analysis of a Middle Pennsylvanian Channel Complex in Pikeville, Kentucky
… the units. This had implications for storage of carbon and paleoclimate studies. Middle Pennsylvanian rivers flowed through tropical rain forests with a high concentration of sediments, and a significant portion of that flux could have been particulate organic carbon derived from the densely …
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Novel analytical strategies for tracing the organic carbon cycle in marine and riverine particles
Particulate organic carbon (POC) in the ocean and mobilized by rivers on land transfers ~0.1% of global primary productivity to the deep ocean sediments. This small fraction regulates the long-term carbon cycle by removing carbon dioxide from the atmosphere for centuries to millennia. This thesis …
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Barium isotope cycling in the marine environment: Pathways of fractionation and implications for paleoceanographic applications
Removal of particulate organic carbon (POC) from sunlit surface waters into the deep ocean represents a climatically important sink of atmospheric carbon dioxide (CO₂), linking the biogeochemical cycling of POC to CO₂-driven climate change. As POC is not well preserved in the sediment record, other …
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Black carbon in the Gulf of Maine : new insights into inputs and cycling of combustion-derived organic carbon
Emissions of black carbon (BC), the soot and char formed during incomplete combustion of fossil and biomass fuels, have increased over the last century and are estimated to be between 8 and 270 Tg BC/yr. BC may affect problems as diverse as global warming, human health, carbon cycling in …
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Novel analytical strategies for tracing the organic carbon cycle in marine and riverine particles
Particulate organic carbon (POC) in the ocean and mobilized by rivers on land transfers -0. 1% of global primary productivity to the deep ocean sediments. This small fraction regulates the long-term carbon cycle by removing carbon dioxide from the atmosphere for centuries to millennia. This thesis …
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Barium isotope cycling in the marine environment: pathways of fractionation and implications for paleoceanographic applications
Removal of particulate organic carbon (POC) from sunlit surface waters into the deep ocean represents a climatically important sink of atmospheric carbon dioxide (CO2), linking the biogeochemical cycling of POC to CO2-driven climate change. As POC is not well preserved in the sediment record, other …
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Anthropogenic and natural radioisotopes as tracers for contaminant sources and particulate fluxes
… into surface export and remineralization of particulate organic carbon (POC) and trace metals (TMs). POC and TMs play a vital role in regulating the biological carbon pump (BCP), which in turn helps to moderate atmospheric CO2 levels by transporting carbon to the deep ocean, where it can be …
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Carbon and Nitrogen Dynamics in High Intensity Minimal Exchange Shrimp (<i>Litopenaeus vannamei</i>) Raceways
… between the 2 density treatments, (2) construct carbon and nitrogen budgets to see where the carbon and nitrogen went in the system for all growouts, (3) determine if plastic media had any effects on water quality parameters and shrimp production, (4) determine if plastic media allowed for a …
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The hydrological flux of organic carbon at the catchment scale: a case study in the Cotter River catchment, Australia
Existing terrestrial carbon accounting models have mainly investigated atmosphere-vegetationsoil stocks and fluxes but have largely ignored the hydrological flux of organic carbon. It is generally assumed that biomass and soil carbon are the only relevant pools in a landscape ecosystem. However, …
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The hydrological flux of organic carbon at the catchment scale: a case study in the Cotter River catchment, Australia
Existing terrestrial carbon accounting models have mainly investigated atmosphere-vegetationsoil stocks and fluxes but have largely ignored the hydrological flux of organic carbon. It is generally assumed that biomass and soil carbon are the only relevant pools in a landscape ecosystem. However, …
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Anthropogenic and natural radioisotopes as tracers for contaminant sources and particulate fluxes
… into surface export and remineralization of particulate organic carbon (POC) and trace metals (TMs). POC and TMs play a vital role in regulating the biological carbon pump (BCP), which in turn helps to moderate atmospheric CO2 levels by transporting carbon to the deep ocean, where it can be …
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An investigation of basin-scale controls on upper ocean export and remineralization
The biological carbon pump (BCP) helps to moderate atmospheric carbon dioxide levels by bringing carbon to the deep ocean, where it can be sequestered on timescales of centuries to millennia. Climate change is predicted to decrease the efficiency of the global BCP, however, the magnitude and …
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Phosphorus Distribution and Partitioning In the Chukchi Sea During Summer 2010
… increase by 0.6 M northwards while dissolved organic P (DOP) concentrations decrease by 0.3 M. However, total P concentrations are similar north (1.34 ├é┬▒ 0.47 M) and south (1.24 ├é┬▒ 0.62 M). P speciation results show that DOP dominates the total (dissolved + particulate) P pool in the …
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