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Chronic Atmospheric Reactive Nitrogen Deposition Suppresses Biological Nitrogen Fixation in Peatlands.

Drijfhout

Chronic Atmospheric Reactive Nitrogen Deposition Suppresses Biological Nitrogen Fixation in Peatlands. Thumbnail


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Abstract

Biological nitrogen fixation (BNF) represents the natural pathway by which mosses meet their demands for bioavailable/reactive nitrogen (Nr) in peatlands. However, following intensification of nitrogen fertilizer and fossil fuel use, atmospheric Nr deposition has increased exposing peatlands to Nr loading often above the ecological threshold. As BNF is energy intensive, therefore, it is unclear whether BNF shuts down when Nr availability is no longer a rarity. We studied the response of BNF under a gradient of Nr deposition extending over decades in three peatlands in the U.K., and at a background deposition peatland in Sweden. Experimental nitrogen fertilization plots in the Swedish site were also evaluated for BNF activity. In situ BNF activity of peatlands receiving Nr deposition of 6, 17, and 27 kg N ha-1 yr-1 was not shut down but rather suppressed by 54, 69, and 74%, respectively, compared to the rates under background Nr deposition of ~2 kg N ha-1 yr-1. These findings were corroborated by similar BNF suppression at the fertilization plots in Sweden. Therefore, contribution of BNF in peatlands exposed to chronic Nr deposition needs accounting when modeling peatland's nitrogen pools, given that nitrogen availability exerts a key control on the carbon capture of peatlands, globally.

Acceptance Date Dec 15, 2020
Publication Date Jan 19, 2021
Publicly Available Date Mar 29, 2024
Journal Environmental Science and Technology
Print ISSN 0013-936X
Publisher American Chemical Society
Pages 1310-1318
DOI https://doi.org/10.1021/acs.est.0c04882
Keywords 15N2 assimilation method, biological nitrogen fixation, Sphagnum mosses, diazotrophs, Nr deposition, peatlands, nitrogen biogeochemistry
Publisher URL https://pubs.acs.org/doi/10.1021/acs.est.0c04882

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