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The fate of fixed n...
The fate of fixed nitrogen in marine sediments with low organic loading : an in situ study
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- Bonaglia, Stefano (author)
- Stockholm University,Lund University,Lunds universitet,Stockholms universitet,Institutionen för geologiska vetenskaper,Kvartärgeologi,Geologiska institutionen,Naturvetenskapliga fakulteten,Quaternary Sciences,Department of Geology,Faculty of Science
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- Hylén, Astrid, 1991 (author)
- Gothenburg University,Göteborgs universitet,University of Gothenburg,Institutionen för marina vetenskaper,Department of marine sciences
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- Rattray, Jayne E. (author)
- Stockholm University
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- Kononets, Mikhail Y, 1978 (author)
- Gothenburg University,Göteborgs universitet,University of Gothenburg,Institutionen för marina vetenskaper,Department of marine sciences
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- Ekeroth, N. (author)
- Gothenburg University,Göteborgs universitet,University of Gothenburg,Calluna AB,Institutionen för marina vetenskaper,Department of marine sciences
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- Roos, Per (author)
- Technical University of Denmark
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- Thamdrup, Bo (author)
- University of Southern Denmark
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- Brüchert, Volker (author)
- Stockholm University
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- Hall, Per, 1954 (author)
- Gothenburg University,Göteborgs universitet,University of Gothenburg,Institutionen för marina vetenskaper,Department of marine sciences
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(creator_code:org_t)
- 2017-01-19
- 2017
- English.
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In: Biogeosciences. - : Copernicus GmbH. - 1726-4170 .- 1726-4189. ; 14:2, s. 285-300
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Abstract
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- 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 (N-2) production by denitrification and anammox (range: 53-360 mu mol Nm(-2) day(-1)) were comparable to those from Arctic and subarctic sediments worldwide (range: 34-344 mu mol Nm(-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.
Subject headings
- NATURVETENSKAP -- Geovetenskap och miljövetenskap -- Geokemi (hsv//swe)
- NATURAL SCIENCES -- Earth and Related Environmental Sciences -- Geochemistry (hsv//eng)
- NATURVETENSKAP -- Geovetenskap och miljövetenskap -- Oceanografi, hydrologi och vattenresurser (hsv//swe)
- NATURAL SCIENCES -- Earth and Related Environmental Sciences -- Oceanography, Hydrology and Water Resources (hsv//eng)
- NATURVETENSKAP -- Geovetenskap och miljövetenskap -- Multidisciplinär geovetenskap (hsv//swe)
- NATURAL SCIENCES -- Earth and Related Environmental Sciences -- Geosciences, Multidisciplinary (hsv//eng)
- NATURVETENSKAP -- Geovetenskap och miljövetenskap -- Geologi (hsv//swe)
- NATURAL SCIENCES -- Earth and Related Environmental Sciences -- Geology (hsv//eng)
Keyword
- Biogeochemistry
- biogeokemi
- Oceanography
- oceanografi
- Marine Geoscience
- marin geovetenskap
Publication and Content Type
- ref (subject category)
- art (subject category)
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- By the author/editor
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Bonaglia, Stefan ...
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Hylén, Astrid, 1 ...
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Rattray, Jayne E ...
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Kononets, Mikhai ...
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Ekeroth, N.
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Roos, Per
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Thamdrup, Bo
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Brüchert, Volker
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Hall, Per, 1954
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- About the subject
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- NATURAL SCIENCES
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NATURAL SCIENCES
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and Earth and Relate ...
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and Geochemistry
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- NATURAL SCIENCES
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NATURAL SCIENCES
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and Earth and Relate ...
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and Oceanography Hyd ...
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- NATURAL SCIENCES
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NATURAL SCIENCES
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and Earth and Relate ...
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and Geosciences Mult ...
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- NATURAL SCIENCES
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NATURAL SCIENCES
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and Earth and Relate ...
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and Geology
- Articles in the publication
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Biogeosciences
- By the university
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Stockholm University
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Lund University
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University of Gothenburg