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Seasonal and event variations in ??34S values of stream sulfate in a Vermont forested catchment: Implications for sulfur sources and cycling

Science of the Total Environment

By:
, , ,
DOI: 10.1016/j.scitotenv.2008.03.020

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Abstract

Stable sulfur (S) isotope ratios can be used to identify the sources of sulfate contributing to streamwater. We collected weekly and high-flow stream samples for S isotopic analysis of sulfate through the entire water year 2003 plus the snowmelt period of 2004. The study area was the 41-ha forested W-9 catchment at Sleepers River Research Watershed, Vermont, a site known to produce sulfate from weathering of sulfide minerals in the bedrock. The ??34S values of streamwater sulfate followed an annual sinusoidal pattern ranging from about 6.5??? in early spring to about 10??? in early fall. During high-flow events, ??34S values typically decreased by 1 to 3??? from the prevailing seasonal value. The isotopic evidence suggests that stream sulfate concentrations are controlled by: (1) an overall dominance of bedrock-derived sulfate (??34S ~ 6-14???); (2) contributions of pedogenic sulfate (??34S ~ 5-6???) during snowmelt and storms with progressively diminishing contributions during base flow recession; and (3) minor effects of dissimilatory bacterial sulfate reduction and subsequent reoxidation of sulfides. Bedrock should not be overlooked as a source of S in catchment sulfate budgets.

Additional Publication Details

Publication type:
Article
Publication Subtype:
Journal Article
Title:
Seasonal and event variations in ??34S values of stream sulfate in a Vermont forested catchment: Implications for sulfur sources and cycling
Series title:
Science of the Total Environment
DOI:
10.1016/j.scitotenv.2008.03.020
Volume
404
Issue:
2-3
Year Published:
2008
Language:
English
Larger Work Type:
Article
Larger Work Subtype:
Journal Article
Larger Work Title:
Science of the Total Environment
First page:
262
Last page:
268
Number of Pages:
7