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A Tracer Test to Determine the Fate of Nitrate in Shallow Groundwater
Author(s) -
Starr J. L.,
Sadeghi A. M.,
Parkin T. B.,
Meisinger J. J.
Publication year - 1996
Publication title -
journal of environmental quality
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.888
H-Index - 171
eISSN - 1537-2537
pISSN - 0047-2425
DOI - 10.2134/jeq1996.00472425002500040037x
Subject(s) - tracer , groundwater , nitrate , sink (geography) , environmental science , soil water , hydrology (agriculture) , soil science , environmental chemistry , groundwater flow , aquifer , chemistry , geology , geotechnical engineering , physics , cartography , organic chemistry , nuclear physics , geography
The effectiveness of shallow groundwater areas to serve as a sink for NO 3 is affected by many biological and physical properties. However, the direct impact of these properties on the fate of NO 3 in shallow groundwater is not well understood, especially where the soils are intermittently saturated. This study was conducted to assess in situ reaction and transport of NO 3 ‐N in an intermittent shallow groundwater system. Tracer experiments were conducted within an imposed constant flowing shallow groundwater. A constant‐head, single injection well technique was adapted for this study using multilevel soil water samplers placed at 14 locations around the center injection well. The use of Br as a tracer for NO 3 ‐N in these constant‐flow experiments provided the means to assess in situ NO 3 ‐N removal both with and without added C. In experiments without added C, an average NO 3 removal rate of 0.33 g N m −2 d −1 was estimated. In a second experiment with dextrose added as an added C source, an average NO 3 loss rate 1.06 g N m −2 d −1 was observed. The observed response to added dextrose indicates that the N removal processes were primarily microbial in origin, i.e., the NO 3 was denitrifled or immobilized into microbial biomass.