Environmental Quality Laboratory, Building 007, Room 201, BARC-West, 10300 Baltimore Avenue, Beltsville, Maryland 20705 (E-Mail/ McCarty: email@example.com).
DISSOLVED GAS ANALYSIS FOR ASSESSING THE FATE OF NITRATE IN WETLANDS1
Article first published online: 8 JUN 2007
JAWRA Journal of the American Water Resources Association
Volume 39, Issue 2, pages 381–387, April 2003
How to Cite
Mookherji, S., McCarty, G. W. and Angier, J. T. (2003), DISSOLVED GAS ANALYSIS FOR ASSESSING THE FATE OF NITRATE IN WETLANDS. JAWRA Journal of the American Water Resources Association, 39: 381–387. doi: 10.1111/j.1752-1688.2003.tb04392.x
Paper No. 01049 of the Journal of the American Water Resources Association.
- Issue published online: 8 JUN 2007
- Article first published online: 8 JUN 2007
- dissolved gases;
- argon (Ar);
- dinitrogen (N2);
- methane (CH4);
- riparian wetland
ABSTRACT: Dissolved gas analysis permits direct detection of ground water denitrification, a technique we used in this study to assess the fate of nitrate in a riparian wetland. Dissolved argon (Ar) and dinitrogen (N2) were measured in transects of nested piezometers installed at different depths within upwelling regions of a riparian wetland. The method uses the Ar content in the water as a natural inert tracer for assessing background content of N2 from the previous air/water equilibrium. Within the wetland under study, anoxic to suboxic ground water became more oxic in piezometers close to the aquifer layer, indicating upwelling of oxic ground water. Assessment of loss of nitrate and Ar in ground water within an upwelling zone indicated that shallow piezometers had significant N2 loss through degassing. Most of the measured nitrate-nitrogen (NO3−-N) loss of 205 μM in a piezometer nest could be accounted for by total N2-N produced (169 μM N), calculated from changes in dissolved N2 and estimated N2 degassed. Degassing due to methane (CH4) production was also detected in some shallow piezometers within nests. This technique for analysis of dissolved gases in ground water can be applied to detect small changes in N gas concentration and aids in assessing the fate of nitrate along a ground water flow path.