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Regional variability in the atmospheric nitrogen deposition signal and its transfer to the sediment record in Greenland lakes

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posted on 08.08.2018, 14:06 by Nicholas John AndersonNicholas John Anderson, Chris J. Curtis, Erika J. Whiteford, Vivienne J. Jones, Suzanne McGowan, Gavin L. Simpson, Jan Kaiser
Disruption of the nitrogen cycle is a major component of global environmental change. δ15N in lake sediments is increasingly used as a measure of reactive nitrogen input but problematically, the characteristic depleted δ15N signal is not recorded at all sites. We used a regionally replicated sampling strategy along a precipitation and N‐deposition gradient in SW Greenland to assess the factors determining the strength of δ15N signal in lake sediment cores. Analyses of snowpack N and δ15N‐NO3 and water chemistry were coupled with bulk sediment δ15N. Study sites cover a gradient of snowpack δ15N (ice sheet: −6‰; coast urn:x-wiley:00243590:media:lno10936:lno10936-math-000110‰), atmospheric N deposition (ice sheet margin: ∼ 0.2 kg ha−1 yr−1; coast: 0.4 kg ha−1 yr−1) and limnology. Three 210Pb‐dated sediment cores from coastal lakes showed a decline in δ15N of ca. urn:x-wiley:00243590:media:lno10936:lno10936-math-00021‰ from ∼ 1860, reflecting the strongly depleted δ15N of snowpack N, lower in‐lake total N (TN) concentration (∼ 300 μg N L−1) and a higher TN‐load. Coastal lakes have 3.7–7.1× more snowpack input of nitrate than inland sites, while for total deposition the values are 1.7–3.6× greater for lake and whole catchment deposition. At inland sites and lakes close to the ice‐sheet margin, a lower atmospheric N deposition rate and larger in‐lake TN pool resulted in greater reliance on N‐fixation and recycling (mean sediment δ15N is 0.5–2.5‰ in most inland lakes; n = 6). The primary control of the transfer of the atmospheric δ15N deposition signal to lake sediments is the magnitude of external N inputs relative to the in‐lake N‐pool.

Funding

Natural Environment Research Council. Grant Number: NE/G019622/1

History

School

  • Social Sciences

Department

  • Geography and Environment

Published in

Limnology and Oceanography

Citation

ANDERSON, N.J. ... et al., 2018. Regional variability in the atmospheric nitrogen deposition signal and its transfer to the sediment record in Greenland lakes. Limnology and Oceanography, 63(5), pp. 2250-2265.

Publisher

Association for the Sciences of Limnology and Oceanography; Published by Wiley

Version

VoR (Version of Record)

Publisher statement

This work is made available according to the conditions of the Creative Commons Attribution 4.0 International (CC BY 4.0) licence. Full details of this licence are available at: http://creativecommons.org/licenses/ by/4.0/

Acceptance date

24/04/2018

Publication date

2018-07-17

Notes

This is an open access article under the terms of the Creative Commons Attribution License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited.

ISSN

1939-5590

Language

en

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