Publication Details

Isotopic signals of summer denitrification in a northern hardwood forested catchment

Publication Toolbox

  • Download PDF (1093863)
  • This publication is available only online.
Wexler, Sarah K.; Goodale, Christine L.; McGuire, Kevin J.; Bailey, Scott W.; Groffman, Peter M.

Year Published

2014

Publication

Proceedings of the National Academy of Sciences. 111(46): 16413-16418.

Abstract

Despite decades of measurements, the nitrogen balance of temperate forest catchments remains poorly understood. Atmospheric nitrogen deposition often greatly exceeds streamwater nitrogen losses; the fate of the remaining nitrogen is highly uncertain. Gaseous losses of nitrogen to denitrification are especially poorly documented and are often ignored. Here, we provide isotopic evidence (δ15NNO3 and δ18ONO3) from shallow groundwater at the Hubbard Brook Experimental Forest indicating extensive denitrification during midsummer, when transient, perched patches of saturation developed in hillslopes, with poor hydrological connectivity to the stream, while streamwater showed no isotopic evidence of denitrification. During small rain events, precipitation directly contributed up to 34% of streamwater nitrate, which was otherwise produced by nitrification. Together, these measurements reveal the importance of denitrification in hydrologically disconnected patches of shallow groundwater during midsummer as largely overlooked control points for nitrogen loss from temperate forest catchments.

Keywords

nitrogen cycle, denitrification, stable isotopes, forested watershed, streamwater chemistry

Citation

Wexler, Sarah K.; Goodale, Christine L.; McGuire, Kevin J.; Bailey, Scott W.; Groffman, Peter M. 2014. Isotopic signals of summer denitrification in a northern hardwood forested catchment. Proceedings of the National Academy of Sciences. 111(46): 16413-16418. https://doi.org/10.1073/pnas.1404321111.

Last updated on: December 17, 2014