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Tracing sources of nitrate in snowmelt runoff using a high-resolution isotopic technique

Geophysical Research Letters

By:
, , , , , ,
DOI: 10.1029/2004GL020908

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Abstract

The denitrifier method to determine the dual isotopic composition (??15N and ??18O) of nitrate is well suited for studies of nitrogen contributions to streams during runoff events. This method requires only 70 nmol of NO3- and enables high throughput of samples. We studied nitrate sources to a headwater stream during snowmelt by generating a high-temporal resolution dataset at the Sleepers River Research Watershed in Vermont, USA. In the earliest phase of runoff, stream NO3- concentrations were highest and stream discharge, NO3- concentrations, and ??18O of NO 3- generally tracked one another during diurnal melting. The isotopic composition of stream NO3- varied in-between atmospheric and groundwater NO 3- end members indicating a direct contribution of atmospherically-derived NO3- from the snow pack to the stream. During the middle to late phases of snowmelt, the source shifted toward soil NO3- entering the stream via shallow subsurface flow paths. Copyright 2004 by the American Geophysical Union.

Additional Publication Details

Publication type:
Article
Publication Subtype:
Journal Article
Title:
Tracing sources of nitrate in snowmelt runoff using a high-resolution isotopic technique
Series title:
Geophysical Research Letters
DOI:
10.1029/2004GL020908
Volume
31
Issue:
21
Year Published:
2004
Language:
English
Larger Work Type:
Article
Larger Work Subtype:
Journal Article
Larger Work Title:
Geophysical Research Letters