Inputs and Biogeochemical Impacts of Nutrient Deposition on the Subtropical North Atlantic
Atmospheric nitrogen deposition to the ocean has more than doubled in the past 150 years due to anthropogenic activity, reaching levels comparable with nitrogen fixation in the subtropical North Atlantic. Previous studies have suggested that atmospherically deposited N may increase export production...
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ftunivmiamiir:oai:scholarlyrepository.miami.edu:oa_dissertations-1476 2023-05-15T17:27:53+02:00 Inputs and Biogeochemical Impacts of Nutrient Deposition on the Subtropical North Atlantic Zamora, Lauren M. Dennis A. Hansell Rana Fine Donald Olson Joseph Prospero Jia-Zhong Zhang 2010-10-06T07:00:00Z application/pdf https://scholarlyrepository.miami.edu/oa_dissertations/477 https://scholarlyrepository.miami.edu/cgi/viewcontent.cgi?article=1476&context=oa_dissertations unknown Scholarly Repository Open Access Dissertations Nutrients New Production Global Change unrestricted 2010 ftunivmiamiir 2019-09-20T22:47:15Z Atmospheric nitrogen deposition to the ocean has more than doubled in the past 150 years due to anthropogenic activity, reaching levels comparable with nitrogen fixation in the subtropical North Atlantic. Previous studies have suggested that atmospherically deposited N may increase export production, decrease surface water phosphate levels, and substantially impact geochemical estimates of nitrogen fixation. This dissertation reports on the magnitude and biogeochemical fate of soluble N and P deposition in the subtropical North Atlantic. Aerosol and wet deposition time-series samples were used to determine the fluxes, sources, and N:P ratios of atmospheric nutrient deposition. Based on the magnitudes of total soluble N and P deposition, atmospheric nutrients are estimated to supply ~10-50% of allochthonous N to the North Atlantic subtropical gyre. Samples gathered in Barbados, the Canary Islands, and Miami indicate that atmospheric N sources are primarily anthropogenic (and thus, increasing) and that P sources are primarily natural (and thus relatively steady). Because inorganic nutrient concentrations in surface waters are in the low nM range, increasing P stress in surface waters may occur as a result of increasing N deposition. This assessment is supported by modeling studies, which also indicate that deposition would enhance surface P depletion. Inorganic N contributes nearly all (85-87%) of atmospherically deposited soluble N; the majority (~60%) of the remaining soluble organic N is comprised of an incompletely characterized pool of volatile basic organic N. Water soluble organic P contributes ~20-50% of soluble P. Because organic P contributes a relatively higher portion of soluble P as compared to organic N, the inclusion of organic matter in deposition estimates could both enhance the expected level of export production and reduce the predicted levels of P stress induced by atmospheric deposition. Further modeling studies indicate that the fate of atmospheric nutrients in the subtropical North Atlantic is controlled by non-Redfieldian processes, and that atmospheric nutrients eventually accumulate in the main thermocline. The research presented here suggests that future increases in atmospheric N emissions could have long-term impacts on surface ocean biology and nutrient cycles in the subtropical North Atlantic. Other/Unknown Material North Atlantic University of Miami: Scholarly Repository |
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University of Miami: Scholarly Repository |
op_collection_id |
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language |
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topic |
Nutrients New Production Global Change |
spellingShingle |
Nutrients New Production Global Change Zamora, Lauren M. Inputs and Biogeochemical Impacts of Nutrient Deposition on the Subtropical North Atlantic |
topic_facet |
Nutrients New Production Global Change |
description |
Atmospheric nitrogen deposition to the ocean has more than doubled in the past 150 years due to anthropogenic activity, reaching levels comparable with nitrogen fixation in the subtropical North Atlantic. Previous studies have suggested that atmospherically deposited N may increase export production, decrease surface water phosphate levels, and substantially impact geochemical estimates of nitrogen fixation. This dissertation reports on the magnitude and biogeochemical fate of soluble N and P deposition in the subtropical North Atlantic. Aerosol and wet deposition time-series samples were used to determine the fluxes, sources, and N:P ratios of atmospheric nutrient deposition. Based on the magnitudes of total soluble N and P deposition, atmospheric nutrients are estimated to supply ~10-50% of allochthonous N to the North Atlantic subtropical gyre. Samples gathered in Barbados, the Canary Islands, and Miami indicate that atmospheric N sources are primarily anthropogenic (and thus, increasing) and that P sources are primarily natural (and thus relatively steady). Because inorganic nutrient concentrations in surface waters are in the low nM range, increasing P stress in surface waters may occur as a result of increasing N deposition. This assessment is supported by modeling studies, which also indicate that deposition would enhance surface P depletion. Inorganic N contributes nearly all (85-87%) of atmospherically deposited soluble N; the majority (~60%) of the remaining soluble organic N is comprised of an incompletely characterized pool of volatile basic organic N. Water soluble organic P contributes ~20-50% of soluble P. Because organic P contributes a relatively higher portion of soluble P as compared to organic N, the inclusion of organic matter in deposition estimates could both enhance the expected level of export production and reduce the predicted levels of P stress induced by atmospheric deposition. Further modeling studies indicate that the fate of atmospheric nutrients in the subtropical North Atlantic is controlled by non-Redfieldian processes, and that atmospheric nutrients eventually accumulate in the main thermocline. The research presented here suggests that future increases in atmospheric N emissions could have long-term impacts on surface ocean biology and nutrient cycles in the subtropical North Atlantic. |
author2 |
Dennis A. Hansell Rana Fine Donald Olson Joseph Prospero Jia-Zhong Zhang |
format |
Other/Unknown Material |
author |
Zamora, Lauren M. |
author_facet |
Zamora, Lauren M. |
author_sort |
Zamora, Lauren M. |
title |
Inputs and Biogeochemical Impacts of Nutrient Deposition on the Subtropical North Atlantic |
title_short |
Inputs and Biogeochemical Impacts of Nutrient Deposition on the Subtropical North Atlantic |
title_full |
Inputs and Biogeochemical Impacts of Nutrient Deposition on the Subtropical North Atlantic |
title_fullStr |
Inputs and Biogeochemical Impacts of Nutrient Deposition on the Subtropical North Atlantic |
title_full_unstemmed |
Inputs and Biogeochemical Impacts of Nutrient Deposition on the Subtropical North Atlantic |
title_sort |
inputs and biogeochemical impacts of nutrient deposition on the subtropical north atlantic |
publisher |
Scholarly Repository |
publishDate |
2010 |
url |
https://scholarlyrepository.miami.edu/oa_dissertations/477 https://scholarlyrepository.miami.edu/cgi/viewcontent.cgi?article=1476&context=oa_dissertations |
genre |
North Atlantic |
genre_facet |
North Atlantic |
op_source |
Open Access Dissertations |
_version_ |
1766120212366622720 |