caa a22 4500 605517398 CHVBK 20210128100719.0 cr unu---uuuuu 210128e20151101xx s 000 0 eng 10.1007/s10533-015-0148-6 doi (NATIONALLICENCE)springer-10.1007/s10533-015-0148-6 Oxygenation of an anoxic fjord basin strongly stimulates benthic denitrification and DNRA [Elektronische Daten] [Loreto De Brabandere, Stefano Bonaglia, Mikhail Kononets, Lena Viktorsson, Anders Stigebrandt, Bo Thamdrup, Per Hall] Hypoxia hampers eutrophication reduction efforts by enabling high nutrient fluxes from sediment to bottom waters. Oxygenation of hypoxic water bodies is often proposed to reduce benthic ammonium and phosphate release. This study investigates the functional response of benthic nitrate-reducing processes to a long-term engineered oxygenation effort in a density-stratified fjord with euxinic bottom waters. Oxygenation was achieved by mixing surface water with deep, euxinic water, which increased oxygen and nitrate concentrations in the deep water column. The presence of nitrate instigated benthic nitrate reduction in the newly oxidized sediments by equally stimulating denitrification and dissimilatory nitrate reduction to ammonium (DNRA). DNRA and total nitrate reduction rates, as well as the contribution of DNRA to total nitrate reduction, decreased with increasing exposure time of the sediments to oxygen. The relative importance of DNRA as a nitrate sink was correlated to nitrate concentrations, with more nitrate being reduced to ammonium at higher bottom water nitrate concentrations. Overall, engineered oxygenation decreased the net efflux of dissolved inorganic nitrogen from the sediments by stimulating net nitrate removal through denitrification. Springer International Publishing Switzerland, 2015 Dissimilatory nitrate reduction nationallicence Denitrification nationallicence DNRA nationallicence Anammox nationallicence Engineered oxygenation nationallicence Hypoxia nationallicence By Fjord nationallicence De Brabandere Loreto Analytical and Environmental Geo-Chemistry, Vrije Universiteit Brussel, 1050, Brussels, Belgium aut Bonaglia Stefano Department of Geological Sciences, Stockholm University, 106 91, Stockholm, Sweden aut Kononets Mikhail Department of Marine Sciences, University of Gothenburg, 412 96, Gothenburg, Sweden aut Viktorsson Lena Department of Marine Sciences, University of Gothenburg, Box 460, 405 30, Gothenburg, Sweden aut Stigebrandt Anders Department of Marine Sciences, University of Gothenburg, Box 460, 405 30, Gothenburg, Sweden aut Thamdrup Bo Nordic Center for Earth Evolution, Department of Biology, University of Southern Denmark, 5230, Odense, Denmark aut Hall Per Department of Marine Sciences, University of Gothenburg, 412 96, Gothenburg, Sweden aut Biogeochemistry Springer International Publishing 126/1-2(2015-11-01), 131-152 0168-2563 126:1-2<131 2015 126 10533 https://doi.org/10.1007/s10533-015-0148-6 text/html Onlinezugriff via DOI BK010053 XK010053 XK010000 Metadata rights reserved Springer special CC-BY-NC licence nationallicence 1 research-article jats NATIONALLICENCE NATIONALLICENCE NL-springer NATIONALLICENCE 856 40 https://doi.org/10.1007/s10533-015-0148-6 text/html Onlinezugriff via DOI NATIONALLICENCE 700 1- De Brabandere Loreto Analytical and Environmental Geo-Chemistry, Vrije Universiteit Brussel, 1050, Brussels, Belgium aut NATIONALLICENCE 700 1- Bonaglia Stefano Department of Geological Sciences, Stockholm University, 106 91, Stockholm, Sweden aut NATIONALLICENCE 700 1- Kononets Mikhail Department of Marine Sciences, University of Gothenburg, 412 96, Gothenburg, Sweden aut NATIONALLICENCE 700 1- Viktorsson Lena Department of Marine Sciences, University of Gothenburg, Box 460, 405 30, Gothenburg, Sweden aut NATIONALLICENCE 700 1- Stigebrandt Anders Department of Marine Sciences, University of Gothenburg, Box 460, 405 30, Gothenburg, Sweden aut NATIONALLICENCE 700 1- Thamdrup Bo Nordic Center for Earth Evolution, Department of Biology, University of Southern Denmark, 5230, Odense, Denmark aut NATIONALLICENCE 700 1- Hall Per Department of Marine Sciences, University of Gothenburg, 412 96, Gothenburg, Sweden aut NATIONALLICENCE 773 0- Biogeochemistry Springer International Publishing 126/1-2(2015-11-01), 131-152 0168-2563 126:1-2<131 2015 126 10533