An analysis of selenium and chloride movement through a pond sediment at Kesterson Reservoir

Technical Report · Thu Sep 01 04:00:00 EDT 1988

OSTI ID:6709076

Long, R H

Kesterson Reservoir, Merced County, CA, a disposal facility for agricultural drain water, became the object of intense scientific investigation after the discovery in 1983 that the disposal of Se- laden agricultural drain waters was having serious effects on the reproductive success of waterfowl. A remedial measure involving permanent flooding with low-Se water, aimed at taking advantage of low Se solubility under reducing conditions, was proposed as a means of limiting Se movement into groundwater and biota. A field experiment was undertaken to evaluate the feasibility of the proposed remedial measure, its impact on the quality of shallow groundwater and for quantifying Se immobilization and transport through a newly-flooded pond bottom soil. Extensive soil water and groundwater sampling demonstrated that although the soluble Se concentrations in the top 1.22 m of soil were initially as high as 1000s of ..mu..g L/sup /minus/1/, Se concentrations declined dramatically after flooding and elevated concentrations below 1.22 m were observed at only one of five sampling sites. Analysis of the temporal and spatial changes in the distribution of dissolved Se and Cl/sup /minus// indicated that 66--108% of the initial soluble Se present in the top 1.22 m was immobilized shortly after flooding. These estimates were consistent with the low Se concentrations observed in shallow monitoring wells. The extent to which Se immobilization occurred was found to correlate inversely with average pore water velocity. Redox measurements indicated that Eh conditions following flooding shifted sufficiently in magnitude and rate to conceivably account for the observed immobilization of selenium. Data presented suggest that reducing conditions in the newly flooded soils lead to the microbially mediated transformation of selenate to less soluble forms. 129 refs., 50 figs., 9 tabs.

• Research Organization: Lawrence Berkeley Lab., CA (USA)
• DOE Contract Number: AC03-76SF00098
• OSTI ID: 6709076
• Report Number(s): LBL-25874; ON: DE89003036
• Country of Publication: United States
• Language: English

Related Subjects

520200* -- Environment
Aquatic-- Chemicals Monitoring & Transport-- (-1989)
54 ENVIRONMENTAL SCIENCES
CALIFORNIA
CHLORIDES
CHLORINE COMPOUNDS
ECOLOGICAL CONCENTRATION
ELEMENTS
FEDERAL REGION IX
GEOLOGY
GROUND WATER
HALIDES
HALOGEN COMPOUNDS
HYDROGEN COMPOUNDS
HYDROLOGY
MATERIALS
MIGRATION
MODIFICATIONS
NORTH AMERICA
OXYGEN COMPOUNDS
PONDS
SEDIMENTS
SELENIUM
SEMIMETALS
SITE CHARACTERIZATION
SOILS
SOLUBILITY
SURFACE WATERS
TOXIC MATERIALS
USA
WATER