WasserCluster Lunz – Inter-university Center for Aquatic Ecosystem Research, Lunz am See, Dr. Carl Kupelwieser Prom. 5, 3293 Lunz/See, Austria
Institute of Hydrobiology and Aquatic Ecosystem Management, Department of Water, Atmosphere and Environment, University of Natural Resources and Life Sciences, Gregor-Mendel-Str. 33, 1180 Vienna, Austria
Aix-Marseille Université, CNRS, Université de Toulon, IRD, MIO UMR 110, 13288 Marseille, France
Juan José Gómez-Alday
Biotechnology and Natural Resources Section, Institute for Regional Development (IDR), University of Castilla–La Mancha (UCLM), Campus Universitario s/n, 02071 Albacete, Spain
Abstract. Nitrate (NO3−) removal from aquatic ecosystems involves several microbially mediated processes including denitrification, dissimilatory nitrate reduction to ammonium (DNRA), and anaerobic ammonium oxidation (anammox) regulated by slight changes in environmental gradients. Saline lakes are prone to the accumulation of anthropogenic contaminants, making them highly vulnerable environments to NO3− pollution. We investigated nitrate removal pathways in mesocosm experiments using lacustrine, undisturbed, organic-rich sediments from Pétrola Lake (Spain), a highly saline waterbody subject to anthropogenic NO3− pollution. We used the revised 15N-isotope pairing technique (15N-IPT) to determine NO3− sink processes. Our results demonstrate the coexistence of denitrification, DNRA, and anammox processes, and their contribution was determined by environmental conditions (oxygen and light). DNRA and N2O-denitrification were the dominant nitrogen (N) removal pathways when oxygen and/or light were present (up to 82 %). In contrast, anoxia and darkness promoted NO3− reduction by DNRA (52 %) and N loss by anammox (28 %). Our results highlight the role of coupled DNRA-anammox, as yet has never been investigated in hypersaline lake ecosystems. We conclude that anoxia and darkness favored DNRA and anammox processes over denitrification and therefore reduce N2O emissions to the atmosphere.
This preprint has been withdrawn.
How to cite. Valiente, N., Jirsa, F., Hein, T., Wanek, W., Bonin, P., and Gómez-Alday, J. J.: Oxygen and light determine the pathways of nitrate reduction in a highly saline lake, Biogeosciences Discuss. [preprint], https://doi.org/10.5194/bg-2020-20, 2020.
Received: 22 Jan 2020 – Discussion started: 31 Jan 2020
Saline lakes are prone to the accumulation of anthropogenic contaminants, making them highly vulnerable environments to nitrate pollution. We used the revised 15N-isotope pairing technique with sediments from a eutrophic hypersaline lake to unravel the nitrate removal pathways carrying on. Our work shows for the first time the coexistence of denitrification, DNRA and anammox in a highly saline/hypersaline lake, with extraordinarily high rates of coupled DNRA-anammox.
Saline lakes are prone to the accumulation of anthropogenic contaminants, making them highly...