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Occurrence and turnover of nitric oxide in a nitrogen-impacted sand and gravel aquifer

Environmental Science and Technology

By:
and
DOI: 10.1021/es801290v

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Abstract

Little is known about nitric oxide (NO) production or consumption in the subsurface, an environment which may be conducive to NO accumulation. A study conducted in a nitrogen-contaminated aquifer on Cape Cod, Massachusetts assessed the occurrence and turnover of NO within a contaminant plume in which nitrification and denitrification were known to occur. NO (up to 8.6 nM) was detected in restricted vertical zones located within a nitrate (NO 3-) gradient and characterized by low dissolved oxygen (<10 ??M). NO concentrations correlated best with nitrite (NO 2-) (up to 35 ??M), but nitrous oxide (N2O) (up to 1 ??M) also was present. Single-well injection tests were used to determine NO production and consumption in situ within these zones. First-order rate constants for NO consumption were similar (0.05-0.08 h-1) at high and low (260 and 10 nM) NO concentrations, suggesting a turnover time at in situ concentrations of 10-20 h. Tracer tests with 15N[NO] demonstrated that oxidation to 15N[NO2-] occurred only during the initial stages, but after 4 h reduction to 15N[N2O] was the primary reaction product Added NO 2- (31 ??M) or NO3- (53 ??M) resulted in a linear NO accumulation at 2.4 and 1.0 nM h-1 for the first 6 h of in situ tests. These results suggest that NO was primarily produced by denitrification within this aquifer. ?? 2008 American Chemical Society.

Additional Publication Details

Publication type:
Article
Publication Subtype:
Journal Article
Title:
Occurrence and turnover of nitric oxide in a nitrogen-impacted sand and gravel aquifer
Series title:
Environmental Science and Technology
DOI:
10.1021/es801290v
Volume
42
Issue:
22
Year Published:
2008
Language:
English
Larger Work Type:
Article
Larger Work Subtype:
Journal Article
Larger Work Title:
Environmental Science and Technology
First page:
8245
Last page:
8251
Number of Pages:
7