Global ETD Search
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Showing 1 to 17 of 17 for “"GEOTRACES"”.
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The Biogeochemistry of iron, zinc and cobalt in the Atlantic Ocean: the Atlantic Meridional Transect and UK GEOTRACES sections
… Atlantic at 40° S were determined during the UK GEOTRACES Section GA10 cruises of October 2010 and December 2011 to January 2012. Iron distributions in North Atlantic surface waters were primarily controlled by the transport and deposition of atmospheric dust particles. In the North Atlantic, …
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The Distribution of Dissolved Barium Along the U.S. Geotraces North Atlantic Transect: Impact of Biogeochemical Processes, Circulation and Phase Association
… were collected during the North Atlantic US GEOTRACES cruises.</p> <p>The cycling of barium in the North Atlantic region was found to be a complex interaction of biological activity and chemical equilibrium combined with an overprinting of ocean circulation. The key findings indicated a …
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The biogeochemistry of marine particulate trace metals
… elements Al, Fe, and Ti in the North Atlantic GEOTRACES section. A one-dimensional multi-box model that describes lithogenic particle distributions is also proposed and its parameter sensitivities and potential implications are discussed. I conclude with presentation of results from a series of …
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Selenium Distribution and Cycling in the Eastern Equatorial Pacific Ocean
… on its chemical speciation. In 2013, the US GEOTRACES program completed the GP16 transect from Peru to Tahiti, going through the oxygen minimum zone off Peru. Dissolved selenate, selenite, and organic selenide, as well as particulate elemental selenium, were determined in water column …
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Anthropogenic and natural radioisotopes as tracers for contaminant sources and particulate fluxes
… 238U:234Th disequilibrium method throughout the GEOTRACES GP15 Pacific Meridional Transect in order o provide basin-scale estimates of POC export and remineralization. There is only limited, recent use of this method to constrain TM fluxes, and as such this study also seeks to further develop …
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The cobalt cycle in the Tropical Pacific Ocean
… are calculated from a global synthesis of recent GEOTRACES data and agree with cobalt accumulation rates in pelagic sediments. Because both sources and sinks are tied to the extent of oxygen minimum zones, oceanic cobalt inventories are likely dynamic on the span of decades. Despite extremely low …
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Understanding Biogeochemical and Physical Controls on Methane Air-Sea Exchange Fluxes in the Pacific Ocean
… and trace element samples were collected on GEOTRACES GP15 Pacific Meridional Transect (PMT) cruise conducted between the Aleutian Islands (57 °N) and Tahiti (20 °S) from September to November 2018. Uncertainty in methane air-sea exchange fluxes was determined using a propagation of errors …
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Anthropogenic and natural radioisotopes as tracers for contaminant sources and particulate fluxes
… 238U:234Th disequilibrium method throughout the GEOTRACES GP15 Pacific Meridional Transect in order to provide basin-scale estimates of POC export and remineralization. There is only limited, recent use of this method to constrain TM fluxes, and as such this study also seeks to further develop …
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The cobalt cycle in the tropical Pacific Ocean
… are calculated from a global synthesis of recent GEOTRACES data and agree with cobalt accumulation rates in pelagic sediments. Because both sources and sinks are tied to the extent of oxygen minimum zones, oceanic cobalt inventories are likely dynamic on the span of decades. Despite extremely low …
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Scavenging and transport of thorium radioisotopes in the North Atlantic Ocean
… as measured or estimated along the GEOTRACES North Atlantic Transect (GA03) and (ii) a model for the reversible exchange of thorium with particles. Model parameters are either estimated by inversion (chapter 2-4), or prescribed in order to simulate 230Th in a circulation model …
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An investigation of basin-scale controls on upper ocean export and remineralization
… using the 234Th-238U method across basin-scale GEOTRACES transects. First, the export and remineralization of POC were examined across large gradients in productivity, upwelling, community structure, and dissolved oxygen in the southeastern tropical Pacific Ocean. Although low oxygen zones are …
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Scavenging and transport of thorium radioisotopes in the North Atlantic Ocean
… as measured or estimated along the GEOTRACES North Atlantic Transect (GA03) and (ii) a model for the reversible exchange of thorium with particles. Model parameters are either estimated by inversion (chapter 2-4), or prescribed in order to simulate 230Th in a circulation model …
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An investigation of basin-scale controls on upper ocean export and remineralization
… using the 234Th- 238U method across basin-scale GEOTRACES transects. First, the export and remineralization of POC were examined across large gradients in productivity, upwelling, community structure, and dissolved oxygen in the southeastern tropical Pacific Ocean. Although low oxygen zones are …
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Marine thorium and protactinium distributions: Tools for past and present chemical flux
… colloidal phases. Finally, results from the U.S. GEOTRACES North Atlantic Transect are used to investigate the relationship between 231Pa and 230Th in the water column and several of their proposed paleoceanographic purposes. The accuracy of 230Th as a proxy for constant sediment flux can be …
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The biogeochemistry of marine particulate trace metals
… elements Al, Fe, and Ti in the North Atlantic GEOTRACES section. Inputs of lithogenic particles from African dust sources, hydrothermal systems, benthic nepheloid layers and laterally-sourced margin influences are observed and discussed. Lithogenic particle residence times, size-fractionation …
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Siderophore cycling in the North Pacific Subtropical Gyre
… of siderophores in the upper 1000 m of the US GEOTRACES GP15 Pacific Meridional Transect. Siderophore concentration ranges from 0-70 pM, and there is no correlation between the concentration of siderophores and dissolved Fe (dFe, <0.2 μm). In contrast, most siderophore hotspots, defined by …
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Distributions and perturbations of the marine dissolved cobalt cycle in a changing ocean
Cobalt is a necessary nutrient for many marine phytoplankton, but its hybrid-type nature results in small marine inventories that make it one of the scarcest bioactive trace metals in the oceans. This study examines the marine dissolved cobalt cycle in two regions: the Pacific Ocean and Antarctic …