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Potential for chemical transport beneath a storm-runoff recharge (retention) basin for an industrial catchment in Fresno, California

Water-Resources Investigations Report 93-4140

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Abstract

A wide variety of chemicals from urban runoff were found at elevated concentrations in sediment that accumulated in a storm-runoff recharge basin in an industrial part of the city of Fresno. The chemicals include as many as 20 inorganic elements and about the same number of organic compounds, primarily organochlorine pesticides and polycyclic aromatic hydrocarbons. Most of these contaminants were found to be sorbed to the upper 4 centimeters of sediment, which also is the maximum depth to which atmospheric lead-210 penetrated. None of the contaminants were detected above background concentrations in the sediment at depths greater than 16 centimeters. In shallow sediment, zinc is the inorganic element that showed the greatest enrichment; its concentration was 38 times higher in surface sediment (0-1 centimeter) than in deeper strata (below 16 centi- meters). Organic carbon enrichment in the surface sediment was nearly 1,000 times. Although batch- elutriation experiments demonstrated the potential for leaching of contaminants attached to sediments, a sharp decrease in concentrations with increasing sediment depth, and the extremely low level of contaminants in two monitor wells adjacent to the basin, confirmed the absence of contaminant transport to the water table. Continued long-term protection for ground water is afforded by an approximately 8-meter-thick unsaturated zone beneath the basin. On the basis of its hundredfold-higher concentration in the recharge pond then in ground water, zinc is indicated as the most sensitive surrogate for monitoring possible ground-water degradation by inorganic cations.

Additional Publication Details

Publication type:
Report
Publication Subtype:
USGS Numbered Series
Title:
Potential for chemical transport beneath a storm-runoff recharge (retention) basin for an industrial catchment in Fresno, California
Series title:
Water-Resources Investigations Report
Series number:
93-4140
Edition:
-
Year Published:
1995
Language:
ENGLISH
Publisher:
U.S. Dept. of the Interior, U.S. Geological Survey ; For sale by the U.S. Geological Survey, Earth Science Information Center, Open-File Reports Section,
Description:
vi, 38 p. :ill., map ;28 cm.