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United States Department of Agriculture

Agricultural Research Service

Title: Assessing N Gas Production in Riparian Wetlands by Dissolved Gas Analysis

Authors
item McCarty, Gregory
item Mookherji, Swati
item Angier, Jonathan

Submitted to: Annual American Geophysical Union Hydrology Days
Publication Type: Abstract Only
Publication Acceptance Date: December 20, 2000
Publication Date: N/A

Technical Abstract: Measurement of dissolved N gases permits direct assessments of groundwater denitrification. For shallow wetland groundwater systems, however, significant production of N gas from denitrification will readily cause the total pressure of dissolved gases to exceed the hydrostatic pressure resulting in loss of dissolved gas through bubble formation (degassing). The changes in dissolved Ar content within a flow path of groundwater provides indication of degassing and permits calculation of the amounts of dissolved gas loss by this mechanism. In the wetland ecosystem studied, the flow paths of groundwater which indicated nitrate attenuation also showed attenuation of Ar. The use of Ar attenuation to calculate the amounts of degassed N2 showed that most of the N gas produced by denitrification in the ecosystem was removed from groundwater by degassing. The N gas production calculated by this procedure largely accounted for nitrate N loss within the system indicating that denitrification was the primary mechanism for nitrate removal from water in the wetland.

Last Modified: 11/27/2014
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