The fate of fixed nitrogen in marine sediments with low organic loading: an in situ study
Over the last decades, the impact of human activities on the global nitrogen (N) cycle has drastically increased. Consequently, benthic N cycling has mainly been studied in anthropogenically impacted estuaries and coasts, while in oligotrophic systems its understanding is still scarce. Here we repor...
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Copernicus Publications
2017
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ftnonlinearchiv:oai:noa.gwlb.de:cop_mods_00042776 2023-05-15T15:19:27+02:00 The fate of fixed nitrogen in marine sediments with low organic loading: an in situ study Bonaglia, Stefano Hylén, Astrid Rattray, Jayne E. Kononets, Mikhail Y. Ekeroth, Nils Roos, Per Thamdrup, Bo Brüchert, Volker Hall, Per O. J. 2017-01 electronic https://doi.org/10.5194/bg-14-285-2017 https://noa.gwlb.de/receive/cop_mods_00042776 https://noa.gwlb.de/servlets/MCRFileNodeServlet/cop_derivate_00042396/bg-14-285-2017.pdf https://bg.copernicus.org/articles/14/285/2017/bg-14-285-2017.pdf eng eng Copernicus Publications Biogeosciences -- http://www.bibliothek.uni-regensburg.de/ezeit/?2158181 -- http://www.copernicus.org/EGU/bg/bg.html -- 1726-4189 https://doi.org/10.5194/bg-14-285-2017 https://noa.gwlb.de/receive/cop_mods_00042776 https://noa.gwlb.de/servlets/MCRFileNodeServlet/cop_derivate_00042396/bg-14-285-2017.pdf https://bg.copernicus.org/articles/14/285/2017/bg-14-285-2017.pdf uneingeschränkt info:eu-repo/semantics/openAccess article Verlagsveröffentlichung article Text doc-type:article 2017 ftnonlinearchiv https://doi.org/10.5194/bg-14-285-2017 2022-02-08T22:40:55Z Over the last decades, the impact of human activities on the global nitrogen (N) cycle has drastically increased. Consequently, benthic N cycling has mainly been studied in anthropogenically impacted estuaries and coasts, while in oligotrophic systems its understanding is still scarce. Here we report on benthic solute fluxes and on rates of denitrification, anammox, and dissimilatory nitrate reduction to ammonium (DNRA) studied by in situ incubations with benthic chamber landers during two cruises to the Gulf of Bothnia (GOB), a cold, oligotrophic basin located in the northern part of the Baltic Sea. Rates of N burial were also inferred to investigate the fate of fixed N in these sediments. Most of the total dissolved fixed nitrogen (TDN) diffusing to the water column was composed of organic N. Average rates of dinitrogen (N2) production by denitrification and anammox (range: 53–360 µmol N m−2 day−1) were comparable to those from Arctic and subarctic sediments worldwide (range: 34–344 µmol N m−2 day−1). Anammox accounted for 18–26 % of the total N2 production. Absence of free hydrogen sulfide and low concentrations of dissolved iron in sediment pore water suggested that denitrification and DNRA were driven by organic matter oxidation rather than chemolithotrophy. DNRA was as important as denitrification at a shallow, coastal station situated in the northern Bothnian Bay. At this pristine and fully oxygenated site, ammonium regeneration through DNRA contributed more than one-third to the TDN efflux and accounted, on average, for 45 % of total nitrate reduction. At the offshore stations, the proportion of DNRA in relation to denitrification was lower (0–16 % of total nitrate reduction). Median value and range of benthic DNRA rates from the GOB were comparable to those from the southern and central eutrophic Baltic Sea and other temperate estuaries and coasts in Europe. Therefore, our results contrast with the view that DNRA is negligible in cold and well-oxygenated sediments with low organic carbon loading. However, the mechanisms behind the variability in DNRA rates between our sites were not resolved. The GOB sediments were a major source (237 kt yr−1, which corresponds to 184 % of the external N load) of fixed N to the water column through recycling mechanisms. To our knowledge, our study is the first to document the simultaneous contribution of denitrification, DNRA, anammox, and TDN recycling combined with in situ measurements. Article in Journal/Newspaper Arctic Subarctic Niedersächsisches Online-Archiv NOA Arctic Biogeosciences 14 2 285 300 |
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English |
topic |
article Verlagsveröffentlichung |
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article Verlagsveröffentlichung Bonaglia, Stefano Hylén, Astrid Rattray, Jayne E. Kononets, Mikhail Y. Ekeroth, Nils Roos, Per Thamdrup, Bo Brüchert, Volker Hall, Per O. J. The fate of fixed nitrogen in marine sediments with low organic loading: an in situ study |
topic_facet |
article Verlagsveröffentlichung |
description |
Over the last decades, the impact of human activities on the global nitrogen (N) cycle has drastically increased. Consequently, benthic N cycling has mainly been studied in anthropogenically impacted estuaries and coasts, while in oligotrophic systems its understanding is still scarce. Here we report on benthic solute fluxes and on rates of denitrification, anammox, and dissimilatory nitrate reduction to ammonium (DNRA) studied by in situ incubations with benthic chamber landers during two cruises to the Gulf of Bothnia (GOB), a cold, oligotrophic basin located in the northern part of the Baltic Sea. Rates of N burial were also inferred to investigate the fate of fixed N in these sediments. Most of the total dissolved fixed nitrogen (TDN) diffusing to the water column was composed of organic N. Average rates of dinitrogen (N2) production by denitrification and anammox (range: 53–360 µmol N m−2 day−1) were comparable to those from Arctic and subarctic sediments worldwide (range: 34–344 µmol N m−2 day−1). Anammox accounted for 18–26 % of the total N2 production. Absence of free hydrogen sulfide and low concentrations of dissolved iron in sediment pore water suggested that denitrification and DNRA were driven by organic matter oxidation rather than chemolithotrophy. DNRA was as important as denitrification at a shallow, coastal station situated in the northern Bothnian Bay. At this pristine and fully oxygenated site, ammonium regeneration through DNRA contributed more than one-third to the TDN efflux and accounted, on average, for 45 % of total nitrate reduction. At the offshore stations, the proportion of DNRA in relation to denitrification was lower (0–16 % of total nitrate reduction). Median value and range of benthic DNRA rates from the GOB were comparable to those from the southern and central eutrophic Baltic Sea and other temperate estuaries and coasts in Europe. Therefore, our results contrast with the view that DNRA is negligible in cold and well-oxygenated sediments with low organic carbon loading. However, the mechanisms behind the variability in DNRA rates between our sites were not resolved. The GOB sediments were a major source (237 kt yr−1, which corresponds to 184 % of the external N load) of fixed N to the water column through recycling mechanisms. To our knowledge, our study is the first to document the simultaneous contribution of denitrification, DNRA, anammox, and TDN recycling combined with in situ measurements. |
format |
Article in Journal/Newspaper |
author |
Bonaglia, Stefano Hylén, Astrid Rattray, Jayne E. Kononets, Mikhail Y. Ekeroth, Nils Roos, Per Thamdrup, Bo Brüchert, Volker Hall, Per O. J. |
author_facet |
Bonaglia, Stefano Hylén, Astrid Rattray, Jayne E. Kononets, Mikhail Y. Ekeroth, Nils Roos, Per Thamdrup, Bo Brüchert, Volker Hall, Per O. J. |
author_sort |
Bonaglia, Stefano |
title |
The fate of fixed nitrogen in marine sediments with low organic loading: an in situ study |
title_short |
The fate of fixed nitrogen in marine sediments with low organic loading: an in situ study |
title_full |
The fate of fixed nitrogen in marine sediments with low organic loading: an in situ study |
title_fullStr |
The fate of fixed nitrogen in marine sediments with low organic loading: an in situ study |
title_full_unstemmed |
The fate of fixed nitrogen in marine sediments with low organic loading: an in situ study |
title_sort |
fate of fixed nitrogen in marine sediments with low organic loading: an in situ study |
publisher |
Copernicus Publications |
publishDate |
2017 |
url |
https://doi.org/10.5194/bg-14-285-2017 https://noa.gwlb.de/receive/cop_mods_00042776 https://noa.gwlb.de/servlets/MCRFileNodeServlet/cop_derivate_00042396/bg-14-285-2017.pdf https://bg.copernicus.org/articles/14/285/2017/bg-14-285-2017.pdf |
geographic |
Arctic |
geographic_facet |
Arctic |
genre |
Arctic Subarctic |
genre_facet |
Arctic Subarctic |
op_relation |
Biogeosciences -- http://www.bibliothek.uni-regensburg.de/ezeit/?2158181 -- http://www.copernicus.org/EGU/bg/bg.html -- 1726-4189 https://doi.org/10.5194/bg-14-285-2017 https://noa.gwlb.de/receive/cop_mods_00042776 https://noa.gwlb.de/servlets/MCRFileNodeServlet/cop_derivate_00042396/bg-14-285-2017.pdf https://bg.copernicus.org/articles/14/285/2017/bg-14-285-2017.pdf |
op_rights |
uneingeschränkt info:eu-repo/semantics/openAccess |
op_doi |
https://doi.org/10.5194/bg-14-285-2017 |
container_title |
Biogeosciences |
container_volume |
14 |
container_issue |
2 |
container_start_page |
285 |
op_container_end_page |
300 |
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1766349637602508800 |