Southern Research Station

Title: Nitrogen trace gas emissions from a riparian ecosystem in southern Appalachia

Author: Walker, John T.; Geron, Christopher D.; Vose, James M.; Swank, Wayne T.

Date: 2002

Source: Chemosphere 49 (2002) 1389-1398

Description: In this paper, we present two years of seasonal nitric oxide (NO), ammonia (NH₃), and nitrous oxide (N₂O) trace gas fluxes measured in a recovering riparian zone with cattle excluded and adjacent riparian zone grazed by cattle. In the recovering riparian zone, average NO, NH₃, and N₂O fluxes were 5.8, 2.0, and 76.7 m^-2 s^-1 (1.83,0.63, and 24.19 kg N ha^-1 y^-1), respectively. Fluxes in the grazed riparian zone were larger, especially for NO and NH₃, measuring 9.1, 4.3, and 77.6 ng N m^-2 s^-1 (2.87, 1.35, and 24.50 kg N ha^-1 y^-1) for NO, NH₃, and N₂O, respectively. On average, N₂O accounted for greater than 85% of total trace gas flux in both the recovering and grazed riparian zones, though N₂O fluxes were highly variable temporally. In the recovering riparian zone, variability in seasonal average fluxes was explained by variability in soil nitrogen (N) concentrations. Nitric oxide flux was positively correlated with soil ammonium (NH⁺₄) concentration, while N₂O flux was positively correlated with soil nitrate (NO^-₄) concentration. Ammonia flux was positively correlated with the ratio of NH⁺₄ to NO^-₃. In the grazed riparian zone, average NH₃ and N₂O fluxes were not correlated with soil temperature, N concentrations, or moisture. This was likely due to high variability in soil microsite conditions related to cattle effects such as compaction and N input. Nitric oxide flux in the grazed riparian zone was positively correlated with soil temperature and NO^-₃ concentration. Restoration appeared to significantly affect NO flux, which increased ~600% during the first year following restoration and decreased during the second year to levels encountered at the onset of restoration. By comparing the ratio of total trace gas flux to soil N concentration, we show that the restored riparian zone is likely more efficient than the grazed riparian zone at diverting upper-soil N from the receiving stream to the atmosphere. This is likely due to the recovery of microbiological communities following changes in soil physical characteristics.

Keywords: Nitrogen, Restoration, Agriculture, Cattle, Riparian buffers

View and Print this Publication (336 KB)

Pristine Version:  An uncaptured or "pristine" version of this publication is available. It has not been subjected to OCR (Optical Character Recognition) and therefore does not have any errors in the text. However it is a larger file size and some people may experience long download times. The "pristine" version of this publication is available here:

View and Print the PRISTINE copy of this Publication (1.5 MB)

Publication Notes: 

• We recommend that you also print this page and attach it to the printout of the article, to retain the full citation information.
• This article was written and prepared by U.S. Government employees on official time, and is therefore in the public domain.

 Get the latest version of the Adobe Acrobat reader or Acrobat Reader for Windows with Search and Accessibility

Citation

Walker, John T.; Geron, Christopher D.; Vose, James M.; Swank, Wayne T.  2002.  Nitrogen trace gas emissions from a riparian ecosystem in southern Appalachia.   Chemosphere 49 (2002) 1389-1398