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Seasonal and event variations in δ34S values of stream sulfate in a Vermont forested catchment: Implications for sulfur sources and cycling

Science of the Total Environment

By:
, , , and
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 δ34S 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, δ34S 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 (δ34S ~ 6–14‰); (2) contributions of pedogenic sulfate (δ34S ~ 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.

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Additional Publication Details

Publication type:
Article
Publication Subtype:
Journal Article
Title:
Seasonal and event variations in δ34S 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
Publisher:
Elsevier
Description:
7 p.
First page:
262
Last page:
268
Country:
United States
State:
Vermont
Other Geospatial:
Sleepers River
Online Only (Y/N):
N
Additional Online Files(Y/N):
N