Interannual variability in the summer dissolved organic matter inventory of the North Sea: implications for the continental shelf pump
We present the distribution and C:N stoichiometry of dissolved organic matter (DOM) in the North Sea in two summers (August 2011 and August 2012), with supporting data from the intervening winter (January 2012). These data demonstrate local variability superimposed on a general pattern of decreasing...
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ftdoajarticles:oai:doaj.org/article:ad59ef6ab0194d13aa3627c596f4312f 2023-05-15T17:32:33+02:00 Interannual variability in the summer dissolved organic matter inventory of the North Sea: implications for the continental shelf pump S. Chaichana T. Jickells M. Johnson 2019-03-01T00:00:00Z https://doi.org/10.5194/bg-16-1073-2019 https://doaj.org/article/ad59ef6ab0194d13aa3627c596f4312f EN eng Copernicus Publications https://www.biogeosciences.net/16/1073/2019/bg-16-1073-2019.pdf https://doaj.org/toc/1726-4170 https://doaj.org/toc/1726-4189 doi:10.5194/bg-16-1073-2019 1726-4170 1726-4189 https://doaj.org/article/ad59ef6ab0194d13aa3627c596f4312f Biogeosciences, Vol 16, Pp 1073-1096 (2019) Ecology QH540-549.5 Life QH501-531 Geology QE1-996.5 article 2019 ftdoajarticles https://doi.org/10.5194/bg-16-1073-2019 2022-12-31T12:12:30Z We present the distribution and C:N stoichiometry of dissolved organic matter (DOM) in the North Sea in two summers (August 2011 and August 2012), with supporting data from the intervening winter (January 2012). These data demonstrate local variability superimposed on a general pattern of decreasing DOM with increasing distance from land, suggesting concentrations of DOM are controlled on large spatial scales by mixing between the open North Atlantic and either riverine sources or high DOM productivity in nearshore coastal waters driven by riverine nutrient discharge. Given the large size and long residence time of water in the North Sea, we find concentrations are commonly modified from simple conservative mixing between two endmembers. We observe differences in dissolved organic carbon (DOC) and dissolved organic nitrogen (DON) concentrations and land–ocean gradients between the two summers, leading to an estimated 10–20 Tg difference in the DOC inventory between the two years, which is of the same order of magnitude as the annual uptake of atmospheric CO 2 by the North Sea system, and thus significant for the carbon budget of the North Sea. This difference is not consistent with additional terrestrial loading and is more likely to be due to balancing of mixing and in situ production and loss processes across the North Sea. Differences were particularly pronounced in the bottom layer of the seasonally stratifying northern North Sea, with higher DOC and C:N ratio in 2011 than in 2012. Using other data, we consider the extent to which these differences in the concentrations and C:N ratio of DOM could be due to changes in the biogeochemistry or physical circulation in the two years, or a combination of both. The evidence we have is consistent with a flushing event in winter 2011/12 exchanging DOM-rich, high C:N shelf waters, which may have accumulated over more than 1 year, with deep North Atlantic waters with lower DOC and marginally higher DON. We discuss the implications of these observations for the shelf sea ... Article in Journal/Newspaper North Atlantic Directory of Open Access Journals: DOAJ Articles Biogeosciences 16 5 1073 1096 |
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Directory of Open Access Journals: DOAJ Articles |
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language |
English |
topic |
Ecology QH540-549.5 Life QH501-531 Geology QE1-996.5 |
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Ecology QH540-549.5 Life QH501-531 Geology QE1-996.5 S. Chaichana T. Jickells M. Johnson Interannual variability in the summer dissolved organic matter inventory of the North Sea: implications for the continental shelf pump |
topic_facet |
Ecology QH540-549.5 Life QH501-531 Geology QE1-996.5 |
description |
We present the distribution and C:N stoichiometry of dissolved organic matter (DOM) in the North Sea in two summers (August 2011 and August 2012), with supporting data from the intervening winter (January 2012). These data demonstrate local variability superimposed on a general pattern of decreasing DOM with increasing distance from land, suggesting concentrations of DOM are controlled on large spatial scales by mixing between the open North Atlantic and either riverine sources or high DOM productivity in nearshore coastal waters driven by riverine nutrient discharge. Given the large size and long residence time of water in the North Sea, we find concentrations are commonly modified from simple conservative mixing between two endmembers. We observe differences in dissolved organic carbon (DOC) and dissolved organic nitrogen (DON) concentrations and land–ocean gradients between the two summers, leading to an estimated 10–20 Tg difference in the DOC inventory between the two years, which is of the same order of magnitude as the annual uptake of atmospheric CO 2 by the North Sea system, and thus significant for the carbon budget of the North Sea. This difference is not consistent with additional terrestrial loading and is more likely to be due to balancing of mixing and in situ production and loss processes across the North Sea. Differences were particularly pronounced in the bottom layer of the seasonally stratifying northern North Sea, with higher DOC and C:N ratio in 2011 than in 2012. Using other data, we consider the extent to which these differences in the concentrations and C:N ratio of DOM could be due to changes in the biogeochemistry or physical circulation in the two years, or a combination of both. The evidence we have is consistent with a flushing event in winter 2011/12 exchanging DOM-rich, high C:N shelf waters, which may have accumulated over more than 1 year, with deep North Atlantic waters with lower DOC and marginally higher DON. We discuss the implications of these observations for the shelf sea ... |
format |
Article in Journal/Newspaper |
author |
S. Chaichana T. Jickells M. Johnson |
author_facet |
S. Chaichana T. Jickells M. Johnson |
author_sort |
S. Chaichana |
title |
Interannual variability in the summer dissolved organic matter inventory of the North Sea: implications for the continental shelf pump |
title_short |
Interannual variability in the summer dissolved organic matter inventory of the North Sea: implications for the continental shelf pump |
title_full |
Interannual variability in the summer dissolved organic matter inventory of the North Sea: implications for the continental shelf pump |
title_fullStr |
Interannual variability in the summer dissolved organic matter inventory of the North Sea: implications for the continental shelf pump |
title_full_unstemmed |
Interannual variability in the summer dissolved organic matter inventory of the North Sea: implications for the continental shelf pump |
title_sort |
interannual variability in the summer dissolved organic matter inventory of the north sea: implications for the continental shelf pump |
publisher |
Copernicus Publications |
publishDate |
2019 |
url |
https://doi.org/10.5194/bg-16-1073-2019 https://doaj.org/article/ad59ef6ab0194d13aa3627c596f4312f |
genre |
North Atlantic |
genre_facet |
North Atlantic |
op_source |
Biogeosciences, Vol 16, Pp 1073-1096 (2019) |
op_relation |
https://www.biogeosciences.net/16/1073/2019/bg-16-1073-2019.pdf https://doaj.org/toc/1726-4170 https://doaj.org/toc/1726-4189 doi:10.5194/bg-16-1073-2019 1726-4170 1726-4189 https://doaj.org/article/ad59ef6ab0194d13aa3627c596f4312f |
op_doi |
https://doi.org/10.5194/bg-16-1073-2019 |
container_title |
Biogeosciences |
container_volume |
16 |
container_issue |
5 |
container_start_page |
1073 |
op_container_end_page |
1096 |
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1766130732316491776 |