Atmospheric Deposition of Nutrients and Excess N Formation in the North Atlantic
Anthropogenic emissions of nitrogen (N) to the atmosphere have been strongly increasing during the last century, leading to greater atmospheric N deposition to the oceans. The North Atlantic subtropical gyre (NASTG) is particularly impacted. Here, upwind sources of anthropogenic N from North America...
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2010
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ftjrc:oai:publications.jrc.ec.europa.eu:JRC54350 2024-09-15T18:22:54+00:00 Atmospheric Deposition of Nutrients and Excess N Formation in the North Atlantic ZAMORRA L.M. LANDOLFI A. OSCHLIES A. HANSELL D.A. DIETZE H. DENTENER Franciscus 2010 Print https://publications.jrc.ec.europa.eu/repository/handle/JRC54350 eng eng COPERNICUS PUBLICATIONS JRC54350 2010 ftjrc 2024-07-22T04:42:14Z Anthropogenic emissions of nitrogen (N) to the atmosphere have been strongly increasing during the last century, leading to greater atmospheric N deposition to the oceans. The North Atlantic subtropical gyre (NASTG) is particularly impacted. Here, upwind sources of anthropogenic N from North American and European sources have raised atmospheric N deposition to rates comparable with N2 fixation in the gyre. However, the biogeochemical fate of the deposited N is unclear because there is no detectable accumulation in the surface waters. Most likely, deposited N accumulates in the main thermocline instead, where there is a globally unique pool of N in excess of the canonical Redfield ratio of 16N:1 phosphorus (P). To investigate this depth zone as a sink for atmospheric N, we used a biogeochemical ocean transport model and year 2000 nutrient deposition data. We examined the maximum effects of three mechanisms that may transport excess N from the ocean surface to the main thermocline: physical transport, preferential P remineralization of sinking particles, and nutrient uptake and export by phytoplankton at higher than Redfield N:P ratios. Our results indicate that atmospheric deposition may contribute 13�19% of the annual excess N input to the main thermocline. Modeled nutrient distributions in the NASTG were comparable to observations only when non-Redfield dynamics were invoked. Preferential P remineralization could not produce realistic results on its own; if it is an important contributor to ocean biogeochemistry, it must co-occur with N2 fixation. The results suggest that: 1) the main thermocline is an important sink for anthropogenic N deposition, 2) non-Redfield surface dynamics determine the biogeochemical fate of atmospherically deposited nutrients, and 3) atmospheric N accumulation in the main thermocline has long term impacts on surface ocean biology. JRC.H.2 - Air and Climate Other/Unknown Material North Atlantic Joint Research Centre, European Commission: JRC Publications Repository |
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Open Polar |
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Joint Research Centre, European Commission: JRC Publications Repository |
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ftjrc |
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English |
description |
Anthropogenic emissions of nitrogen (N) to the atmosphere have been strongly increasing during the last century, leading to greater atmospheric N deposition to the oceans. The North Atlantic subtropical gyre (NASTG) is particularly impacted. Here, upwind sources of anthropogenic N from North American and European sources have raised atmospheric N deposition to rates comparable with N2 fixation in the gyre. However, the biogeochemical fate of the deposited N is unclear because there is no detectable accumulation in the surface waters. Most likely, deposited N accumulates in the main thermocline instead, where there is a globally unique pool of N in excess of the canonical Redfield ratio of 16N:1 phosphorus (P). To investigate this depth zone as a sink for atmospheric N, we used a biogeochemical ocean transport model and year 2000 nutrient deposition data. We examined the maximum effects of three mechanisms that may transport excess N from the ocean surface to the main thermocline: physical transport, preferential P remineralization of sinking particles, and nutrient uptake and export by phytoplankton at higher than Redfield N:P ratios. Our results indicate that atmospheric deposition may contribute 13�19% of the annual excess N input to the main thermocline. Modeled nutrient distributions in the NASTG were comparable to observations only when non-Redfield dynamics were invoked. Preferential P remineralization could not produce realistic results on its own; if it is an important contributor to ocean biogeochemistry, it must co-occur with N2 fixation. The results suggest that: 1) the main thermocline is an important sink for anthropogenic N deposition, 2) non-Redfield surface dynamics determine the biogeochemical fate of atmospherically deposited nutrients, and 3) atmospheric N accumulation in the main thermocline has long term impacts on surface ocean biology. JRC.H.2 - Air and Climate |
author |
ZAMORRA L.M. LANDOLFI A. OSCHLIES A. HANSELL D.A. DIETZE H. DENTENER Franciscus |
spellingShingle |
ZAMORRA L.M. LANDOLFI A. OSCHLIES A. HANSELL D.A. DIETZE H. DENTENER Franciscus Atmospheric Deposition of Nutrients and Excess N Formation in the North Atlantic |
author_facet |
ZAMORRA L.M. LANDOLFI A. OSCHLIES A. HANSELL D.A. DIETZE H. DENTENER Franciscus |
author_sort |
ZAMORRA L.M. |
title |
Atmospheric Deposition of Nutrients and Excess N Formation in the North Atlantic |
title_short |
Atmospheric Deposition of Nutrients and Excess N Formation in the North Atlantic |
title_full |
Atmospheric Deposition of Nutrients and Excess N Formation in the North Atlantic |
title_fullStr |
Atmospheric Deposition of Nutrients and Excess N Formation in the North Atlantic |
title_full_unstemmed |
Atmospheric Deposition of Nutrients and Excess N Formation in the North Atlantic |
title_sort |
atmospheric deposition of nutrients and excess n formation in the north atlantic |
publisher |
COPERNICUS PUBLICATIONS |
publishDate |
2010 |
url |
https://publications.jrc.ec.europa.eu/repository/handle/JRC54350 |
genre |
North Atlantic |
genre_facet |
North Atlantic |
op_relation |
JRC54350 |
_version_ |
1810462940284846080 |