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Nitrogen and oxygen availabilities control water column nitrous oxide production during seasonal anoxia in the Chesapeake Bay

Ji, Qixing and Frey, Claudia and Sun, Xin and Jackson, Melanie and Lee, Yea-Shine and Jayakumar, Amal and Cornwell, Jeffrey C. and Ward, Bess B.. (2018) Nitrogen and oxygen availabilities control water column nitrous oxide production during seasonal anoxia in the Chesapeake Bay. BIOGEOSCIENCES, 15 (20). pp. 6127-6138.

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Official URL: https://edoc.unibas.ch/66980/

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Abstract

Nitrous oxide (N2O) is a greenhouse gas and an ozone depletion agent. Estuaries that are subject to seasonal anoxia are generally regarded as N2O sources. However, insufficient understanding of the environmental controls on N2O production results in large uncertainty about the estuarine contribution to the global N2O budget. Incubation experiments with nitrogen stable isotope tracer were used to investigate the geochemical factors controlling N2O production from denitrification in the Chesapeake Bay, the largest estuary in North America. The highest potential rates of water column N2O production via denitrification (7.5 +/- 1.2 nmol-N L(-1 )h(-1)) were detected during summer anoxia, during which oxidized nitrogen species (nitrate and nitrite) were absent from the water column. At the top of the anoxic layer, N2O production from denitrification was stimulated by addition of nitrate and nitrite. The relative contribution of nitrate and nitrite to N2O production was positively correlated with the ratio of nitrate to nitrite concentrations. Increased oxygen availability, up to 7 mu mol L-1 oxygen, inhibited both N2O production and the reduction of nitrate to nitrite. In spring, high oxygen and low abundance of denitrifying microbes resulted in undetectable N2O production from denitrification. Thus, decreasing the nitrogen input into the Chesapeake Bay has two potential impacts on the N2O production: a lower availability of nitrogen substrates may mitigate short-term N2O emissions during summer anoxia; and, in the long-run (timescale of years), eutrophication will be alleviated and subsequent reoxygenation of the bay will further inhibit N2O production.
Faculties and Departments:05 Faculty of Science
05 Faculty of Science > Departement Umweltwissenschaften
05 Faculty of Science > Departement Umweltwissenschaften > Geowissenschaften > Geochemie Stoffkreisläufe (Lehmann)
UniBasel Contributors:Frey, Claudia
Item Type:Article, refereed
Article Subtype:Research Article
Publisher:COPERNICUS GESELLSCHAFT MBH
ISSN:1726-4170
Note:Publication type according to Uni Basel Research Database: Journal article
Identification Number:
Last Modified:26 Apr 2020 19:06
Deposited On:26 Apr 2020 19:06

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