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Winter nitrification in ice-covered lakes

With changes in ice cover duration, nutrient loading, and anoxia risk, it is important to understand the mechanisms that control nitrogen cycling and oxygen depletion in lakes through winter. Current understanding is largely limited to description of changes in chemistry, with few measurements of th...

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Autores principales: Cavaliere, Emily, Baulch, Helen M.
Formato: Online Artículo Texto
Lenguaje:English
Publicado: Public Library of Science 2019
Materias:
Acceso en línea:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6837456/
https://www.ncbi.nlm.nih.gov/pubmed/31697768
http://dx.doi.org/10.1371/journal.pone.0224864
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author Cavaliere, Emily
Baulch, Helen M.
author_facet Cavaliere, Emily
Baulch, Helen M.
author_sort Cavaliere, Emily
collection PubMed
description With changes in ice cover duration, nutrient loading, and anoxia risk, it is important to understand the mechanisms that control nitrogen cycling and oxygen depletion in lakes through winter. Current understanding is largely limited to description of changes in chemistry, with few measurements of the processes driving winter changes, how they differ across lakes, and how they are impacted by under-ice conditions. Nitrification is a process which consumes oxygen and ammonium (NH(4)(+)), and supplies nitrate (NO(3)(–)). To date, nitrification has been measured under ice cover in only two lakes globally. Here, we used (15)NH(4)(+) enrichment to measure rates of pelagic nitrification in thirteen water bodies in two ecozones. Our work demonstrates ecologically important rates of nitrification can occur despite low water temperatures, impacting NH(4)(+), NO(3)(–) and, most importantly, oxygen concentrations. However, high rates are not the norm. When, where and why is nitrification important in winter? We found that nitrification rates were highest in a eutrophic lake chain downstream of a wastewater treatment effluent (mean: 226.5 μg N L(-1) d(-1)), and in a semi-saline prairie lake (110.0 μg N L(-1) d(-1)). In the boreal shield, a eutrophic lake had nitrification rates exceeding those of an oligotrophic lake by 6-fold. Supplementing our results with literature data we found NH(4)(+) concentrations were the strongest predictor of nitrification rates across lentic ecosystems in winter. Higher nitrification rates were associated with higher concentrations of NH(4)(+), NO(3)(–) and nitrous oxide (N(2)O). While more work is required to understand the switch between high and low nitrification rates and strengthen our understanding of winter nitrogen cycling, this work demonstrates that high nitrification rates can occur in winter.
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spelling pubmed-68374562019-11-14 Winter nitrification in ice-covered lakes Cavaliere, Emily Baulch, Helen M. PLoS One Research Article With changes in ice cover duration, nutrient loading, and anoxia risk, it is important to understand the mechanisms that control nitrogen cycling and oxygen depletion in lakes through winter. Current understanding is largely limited to description of changes in chemistry, with few measurements of the processes driving winter changes, how they differ across lakes, and how they are impacted by under-ice conditions. Nitrification is a process which consumes oxygen and ammonium (NH(4)(+)), and supplies nitrate (NO(3)(–)). To date, nitrification has been measured under ice cover in only two lakes globally. Here, we used (15)NH(4)(+) enrichment to measure rates of pelagic nitrification in thirteen water bodies in two ecozones. Our work demonstrates ecologically important rates of nitrification can occur despite low water temperatures, impacting NH(4)(+), NO(3)(–) and, most importantly, oxygen concentrations. However, high rates are not the norm. When, where and why is nitrification important in winter? We found that nitrification rates were highest in a eutrophic lake chain downstream of a wastewater treatment effluent (mean: 226.5 μg N L(-1) d(-1)), and in a semi-saline prairie lake (110.0 μg N L(-1) d(-1)). In the boreal shield, a eutrophic lake had nitrification rates exceeding those of an oligotrophic lake by 6-fold. Supplementing our results with literature data we found NH(4)(+) concentrations were the strongest predictor of nitrification rates across lentic ecosystems in winter. Higher nitrification rates were associated with higher concentrations of NH(4)(+), NO(3)(–) and nitrous oxide (N(2)O). While more work is required to understand the switch between high and low nitrification rates and strengthen our understanding of winter nitrogen cycling, this work demonstrates that high nitrification rates can occur in winter. Public Library of Science 2019-11-07 /pmc/articles/PMC6837456/ /pubmed/31697768 http://dx.doi.org/10.1371/journal.pone.0224864 Text en © 2019 Cavaliere, Baulch http://creativecommons.org/licenses/by/4.0/ This is an open access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/4.0/) , which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.
spellingShingle Research Article
Cavaliere, Emily
Baulch, Helen M.
Winter nitrification in ice-covered lakes
title Winter nitrification in ice-covered lakes
title_full Winter nitrification in ice-covered lakes
title_fullStr Winter nitrification in ice-covered lakes
title_full_unstemmed Winter nitrification in ice-covered lakes
title_short Winter nitrification in ice-covered lakes
title_sort winter nitrification in ice-covered lakes
topic Research Article
url https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6837456/
https://www.ncbi.nlm.nih.gov/pubmed/31697768
http://dx.doi.org/10.1371/journal.pone.0224864
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