Preprints
https://doi.org/10.5194/bg-2020-20
https://doi.org/10.5194/bg-2020-20
31 Jan 2020
 | 31 Jan 2020
Status: this preprint has been withdrawn by the authors.

Oxygen and light determine the pathways of nitrate reduction in a highly saline lake

Nicolás Valiente, Franz Jirsa, Thomas Hein, Wolfgang Wanek, Patricia Bonin, and Juan José Gómez-Alday

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This preprint has been withdrawn.

Nicolás Valiente, Franz Jirsa, Thomas Hein, Wolfgang Wanek, Patricia Bonin, and Juan José Gómez-Alday

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Status: closed
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Interactive discussion

Status: closed
Status: closed
AC: Author comment | RC: Referee comment | SC: Short comment | EC: Editor comment
Printer-friendly Version - Printer-friendly version Supplement - Supplement
Nicolás Valiente, Franz Jirsa, Thomas Hein, Wolfgang Wanek, Patricia Bonin, and Juan José Gómez-Alday
Nicolás Valiente, Franz Jirsa, Thomas Hein, Wolfgang Wanek, Patricia Bonin, and Juan José Gómez-Alday

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Short summary
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.
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