Weyhenmeyer, Gesa
- Department of Aquatic Sciences and Assessment, Swedish University of Agricultural Sciences
Abstract
With a unique data set comprising 1041 boreal forested and low human impacted lakes included in three Swedish lake inventories for 1995, 2000 and 2005 and with time series for 12 of the lakes from 1988 to 2008 we show that nitrate-nitrogen (NO3-N) is accumulated in freshwaters along with increasing atmospheric nitrogen deposition (N-dep). At the same time we observe decreasing DOC : NO3-N ratios in the water column. We suggest that NO3-N is accumulated in freshwaters when denitrifying bacteria are limited by their energy source rather than the availability of NO3-N, i.e. at low DOC : NO3-N ratios. We obtained further support for a close relationship between N-dep driven DOC : NO3-N ratios and the efficiency of nitrate removal by using a published global data set on measured nitrate removal rates in unproductive reference streams. Owing to the currently decreasing N-dep in large regions of, for instance, Northern Europe, this process is now reversed, resulting in increasing DOC : NO3-N ratios and more efficient nitrate removal from freshwaters. Depending on NOx emissions, nitrogen limited regions may expand with an immediate effect on nitrate concentrations in freshwaters.
Keywords
boreal lakes; carbon; climate; denitrification; deposition net ecosystem production; nitrogen saturation
Published in
Global Change Biology
2010, volume: 16, number: 8, pages: 2358-2365
Publisher: WILEY-BLACKWELL
SLU Authors
Associated SLU-program
Eutrophication
Lakes and watercourses
UKÄ Subject classification
Ecology
Fish and Aquacultural Science
Environmental Sciences
Publication identifier
- DOI: https://doi.org/10.1111/j.1365-2486.2009.02100.x
Permanent link to this page (URI)
https://res.slu.se/id/publ/60490