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Mechanisms of iron photoreduction in a metal-rich, acidic stream (St. Kevin Gulch, Colorado, U.S.A.)

Chemical Geology

By:
, , , and
DOI: 10.1016/0009-2541(92)90130-W

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Abstract

Iron photoreduction in metal-rich, acidic streams affected by mine drainage accounts for some of the variability in metal chemistry of such streams, producing diel variations in Fe(II). Differentiation of the mechanisms of the Fe photoreduction reaction by a series of in-stream experiments at St. Kevin Gulch, Colorado, indicates that a homogeneous, solution-phase reaction can occur in the absence of suspended particulate Fe and bacteria, and the rate of reaction is increased by the presence of Fe colloids in the stream water. In-stream Fe photoreduction is limited during the diel cycle by the available Fe(III) in the water column and streambed. The quantum yield of Fe(II) was reproducible in diel measurements: the quantum yield, in mol E-1 (from 300 to 400 nm) was 1.4 ?? 10-3 in 1986, 0.8 ?? 10-3 in 1988 and 1.2 ?? 10-3 in 1989, at the same location and under similar streamflow and stream-chemistry conditions. In a photolysis control experiment, there was no detectable production of Fe(II) above background concentrations in stream-water samples that were experimentally excluded from sunlight. ?? 1992.

Additional Publication Details

Publication type:
Article
Publication Subtype:
Journal Article
Title:
Mechanisms of iron photoreduction in a metal-rich, acidic stream (St. Kevin Gulch, Colorado, U.S.A.)
Series title:
Chemical Geology
DOI:
10.1016/0009-2541(92)90130-W
Volume
96
Issue:
1-2
Year Published:
1992
Language:
English
Publisher:
Elsevier
Larger Work Type:
Article
Larger Work Subtype:
Journal Article
Larger Work Title:
Chemical Geology
First page:
227
Last page:
239