Distributions of pesticides and organic contaminants between water and suspended sediment, San Francisco Bay, California
- Department of the Interior, Sacramento, CA (United States)
Suspended-sediment and water samples were collected from San Francisco Bay in 1991 during low river discharge and after spring rains. All samples were analyzed for organophosphate, carbamate, and organochlorine pesticides; petroleum hydrocarbons; biomarkers; and polynuclear aromatic hydrocarbons. The objective were to determine the concentrations of these contaminants in water and suspended sediment during two different hydrologic conditions and to determine partition coefficients of the contaminants between water and sediment. Concentrations of hydrophobic contaminants, such as polynuclear aromatic hydrocarbons, varied with location of sample collection, riverine discharge, and tidal cycle. Concentrations of hydrophobic contaminants in suspended sediments were highest during low river discharge but became diluted as agricultural soils entered the bay after spring rains. Polynuclear aromatic hydrocarbons defined as dissolved in the water column were not detected. The concentrations sorbed on suspended sediments were variable and were dependent on sediment transport patterns in the bay. In contrast, the relatively hydrophilic organophosphate pesticides, such as chlorpyrifos and diazinon, had a ore uniform concentration in suspended sediment. These pesticides were detected only after spring rains. Most of the measured diazinon, at least 98% for all samples, was in the dissolved phase. Measured partition coefficients for diazinon generally were uniform, which suggest that suspended-sediment concentrations were close to equilibrium with dissolved concentrations. The concentration of diazinon sorbed to suspended sediments, at any given sampling site, was driven primarily by the more abundant solution concentration. The concentrations of diazinon sorbed to suspended sediments, therefore, were independent of the patterns of sediment movement. 27 refs., 5 figs., 4 tabs.
- OSTI ID:
- 7285979
- Journal Information:
- Estuaries; (United States), Vol. 16:3A; ISSN 0160-8347
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
POLLUTANTS
ECOLOGICAL CONCENTRATION
SPATIAL DISTRIBUTION
VARIATIONS
SAN FRANCISCO BAY
CONTAMINATION
PESTICIDES
PETROLEUM FRACTIONS
POLYCYCLIC AROMATIC HYDROCARBONS
AROMATICS
DISTRIBUTION
ENERGY SOURCES
FOSSIL FUELS
FUELS
HYDROCARBONS
ORGANIC COMPOUNDS
PACIFIC OCEAN
PETROLEUM
SEAS
SURFACE WATERS
540320* - Environment
Aquatic- Chemicals Monitoring & Transport- (1990-)