Groundwater contamination at the Kesterson Reservoir, California. 2. Geochemical parameters influencing selenium mobility

Journal Article · Sat Jun 01 04:00:00 EDT 1991 · Water Resources Research; (United States)

DOI:https://doi.org/10.1029/91WR00264· OSTI ID:5745805

White, A F; Benson, S M; Yee, A W; Wollenberg, Jr, H A; Flexser, S ^[1]

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1. Univ. of California, Berkeley (United States)

Transport of selenium in groundwater at the Kesterson Reservoir in the Central Valley of California was strongly retarded because of chemical reduction and precipitation mediated by microbial activity. Under such conditions, negative correlations were documented between aqueous Se and Fe{sup 2+}, Mn, and H{sub 2}S. Locally, the presence of oxidizing species, notably O{sub 2} and NO{sub 3}, suppressed this reduction, permitting Se mobilization in the shallow aquifer. Selenate, the dominant and most oxidized form of Se, was in electrochemical disequilibrium with subordinate concentrations of selenite. Normally slow inorganic reduction rates were accelerated by microbial activity which utilizes oxidized chemical species including selenate as electron donors during the oxidation of organic matter. Two stratified redox barriers to selenium migration were documented beneath Kesterson: an underlying shallow anoxic zone underlying most of the pond bottom, characterized by high organic content and sulfate reduction, and a deeper dynamic front established by localized O{sub 2} infiltration from the overlying ponds and Fe{sup 2+} release from aquifer materials. The reducing nature of this deeper aquifer ultimately precludes Se transport to regional groundwater.

• OSTI ID: 5745805
• Journal Information: Water Resources Research; (United States), Journal Name: Water Resources Research; (United States) Vol. 27:6; ISSN 0043-1397; ISSN WRERA
• Country of Publication: United States
• Language: English

Related Subjects

54 ENVIRONMENTAL SCIENCES
540320* -- Environment
Aquatic-- Chemicals Monitoring & Transport-- (1990-)
AQUIFERS
BIODEGRADATION
BIOGEOCHEMISTRY
CALIFORNIA
CHALCOGENIDES
CHEMICAL REACTIONS
CHEMISTRY
CONTAMINATION
DECOMPOSITION
DEVELOPED COUNTRIES
ELEMENTS
ENVIRONMENTAL TRANSPORT
GEOCHEMISTRY
GROUND WATER
HYDROGEN COMPOUNDS
HYDROGEN SULFIDES
IRON COMPOUNDS
MANGANESE
MASS TRANSFER
MATTER
METALS
NITRATES
NITROGEN COMPOUNDS
NONMETALS
NORTH AMERICA
ORGANIC MATTER
OXYGEN
OXYGEN COMPOUNDS
REDOX REACTIONS
SELENIUM
SEMIMETALS
SULFATES
SULFIDES
SULFUR COMPOUNDS
SURFACE WATERS
TRANSITION ELEMENT COMPOUNDS
TRANSITION ELEMENTS
USA
WATER
WATER RESERVOIRS