Oxygen, carbon, and nutrients in the oligotrophic eastern subtropical North Atlantic
The Beta Triangle, a region of the oligotrophic subtropical eastern North Atlantic Ocean, is notorious for its enigmatic oxygen, carbon, and nitrogen balances, in which nutrient supply is said to explain only a fraction of production necessary for estimated carbon export. Rates of dissolved organic...
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ftdoajarticles:oai:doaj.org/article:4da13d9d29f2472d8ffd55fd7d104345 2023-05-15T17:32:04+02:00 Oxygen, carbon, and nutrients in the oligotrophic eastern subtropical North Atlantic P. Kähler A. Oschlies H. Dietze W. Koeve 2010-03-01T00:00:00Z https://doaj.org/article/4da13d9d29f2472d8ffd55fd7d104345 EN eng Copernicus Publications http://www.biogeosciences.net/7/1143/2010/bg-7-1143-2010.pdf https://doaj.org/toc/1726-4170 https://doaj.org/toc/1726-4189 1726-4170 1726-4189 https://doaj.org/article/4da13d9d29f2472d8ffd55fd7d104345 Biogeosciences, Vol 7, Iss 3, Pp 1143-1156 (2010) Ecology QH540-549.5 Life QH501-531 Geology QE1-996.5 article 2010 ftdoajarticles 2022-12-31T08:46:50Z The Beta Triangle, a region of the oligotrophic subtropical eastern North Atlantic Ocean, is notorious for its enigmatic oxygen, carbon, and nitrogen balances, in which nutrient supply is said to explain only a fraction of production necessary for estimated carbon export. Rates of dissolved organic carbon accumulation and dissolved organic nitrogen utilization in surface water and an assessment of oxygen utilized, organic matter consumed, and nitrate and phosphate regenerated in subsurface water, show that conventional production estimates miss substantial shares of biotic production. The shallow export of total organic carbon, predominantly dissolved (DOC), by subduction is responsible for about 50–70% of apparent oxygen utilization in subsurface water between the base of the surface layer at ca. 140 m and ca. 195 m depth, but it is insignificant below. Additionally, there is an estimated accumulation of 1.0 to 1.75 mol DOC m −2 a −1 in surface water. Including DOC dynamics in its carbon balance reveals the surface of this ultra-oligotrophic part of the ocean to be net autotrophic. Increasing subsurface values of excess nitrogen (DINxs) imply the export of nitrogen from surface water stemming from production not exclusively fuelled by new nitrate supplied from below. Total organic nitrogen (almost exclusively dissolved, DON) is consumed in the surface layer at a rate estimated at 0.13 to 0.23 mol m −2 a −1 . There is no variation in dissolved organic phosphorus (DOP) in the same direction. DON utilization thus contributes to the pronounced subsurface DINxs signature. DOC export and accumulation are important in the carbon balance in surface and near-surface water. DON utilization and, probably, N 2 fixation contribute significant amounts to the nitrogen supply of surface water. These processes can close part of the enigmatic carbon and nitrogen balances in the Beta Triangle. There are, however, no comparable processes which can explain the equally enigmatic situation concerning phosphorus supply in this area. Article in Journal/Newspaper North Atlantic Directory of Open Access Journals: DOAJ Articles |
institution |
Open Polar |
collection |
Directory of Open Access Journals: DOAJ Articles |
op_collection_id |
ftdoajarticles |
language |
English |
topic |
Ecology QH540-549.5 Life QH501-531 Geology QE1-996.5 |
spellingShingle |
Ecology QH540-549.5 Life QH501-531 Geology QE1-996.5 P. Kähler A. Oschlies H. Dietze W. Koeve Oxygen, carbon, and nutrients in the oligotrophic eastern subtropical North Atlantic |
topic_facet |
Ecology QH540-549.5 Life QH501-531 Geology QE1-996.5 |
description |
The Beta Triangle, a region of the oligotrophic subtropical eastern North Atlantic Ocean, is notorious for its enigmatic oxygen, carbon, and nitrogen balances, in which nutrient supply is said to explain only a fraction of production necessary for estimated carbon export. Rates of dissolved organic carbon accumulation and dissolved organic nitrogen utilization in surface water and an assessment of oxygen utilized, organic matter consumed, and nitrate and phosphate regenerated in subsurface water, show that conventional production estimates miss substantial shares of biotic production. The shallow export of total organic carbon, predominantly dissolved (DOC), by subduction is responsible for about 50–70% of apparent oxygen utilization in subsurface water between the base of the surface layer at ca. 140 m and ca. 195 m depth, but it is insignificant below. Additionally, there is an estimated accumulation of 1.0 to 1.75 mol DOC m −2 a −1 in surface water. Including DOC dynamics in its carbon balance reveals the surface of this ultra-oligotrophic part of the ocean to be net autotrophic. Increasing subsurface values of excess nitrogen (DINxs) imply the export of nitrogen from surface water stemming from production not exclusively fuelled by new nitrate supplied from below. Total organic nitrogen (almost exclusively dissolved, DON) is consumed in the surface layer at a rate estimated at 0.13 to 0.23 mol m −2 a −1 . There is no variation in dissolved organic phosphorus (DOP) in the same direction. DON utilization thus contributes to the pronounced subsurface DINxs signature. DOC export and accumulation are important in the carbon balance in surface and near-surface water. DON utilization and, probably, N 2 fixation contribute significant amounts to the nitrogen supply of surface water. These processes can close part of the enigmatic carbon and nitrogen balances in the Beta Triangle. There are, however, no comparable processes which can explain the equally enigmatic situation concerning phosphorus supply in this area. |
format |
Article in Journal/Newspaper |
author |
P. Kähler A. Oschlies H. Dietze W. Koeve |
author_facet |
P. Kähler A. Oschlies H. Dietze W. Koeve |
author_sort |
P. Kähler |
title |
Oxygen, carbon, and nutrients in the oligotrophic eastern subtropical North Atlantic |
title_short |
Oxygen, carbon, and nutrients in the oligotrophic eastern subtropical North Atlantic |
title_full |
Oxygen, carbon, and nutrients in the oligotrophic eastern subtropical North Atlantic |
title_fullStr |
Oxygen, carbon, and nutrients in the oligotrophic eastern subtropical North Atlantic |
title_full_unstemmed |
Oxygen, carbon, and nutrients in the oligotrophic eastern subtropical North Atlantic |
title_sort |
oxygen, carbon, and nutrients in the oligotrophic eastern subtropical north atlantic |
publisher |
Copernicus Publications |
publishDate |
2010 |
url |
https://doaj.org/article/4da13d9d29f2472d8ffd55fd7d104345 |
genre |
North Atlantic |
genre_facet |
North Atlantic |
op_source |
Biogeosciences, Vol 7, Iss 3, Pp 1143-1156 (2010) |
op_relation |
http://www.biogeosciences.net/7/1143/2010/bg-7-1143-2010.pdf https://doaj.org/toc/1726-4170 https://doaj.org/toc/1726-4189 1726-4170 1726-4189 https://doaj.org/article/4da13d9d29f2472d8ffd55fd7d104345 |
_version_ |
1766130004250329088 |