Suspended sediments were obtained at seven stations in San Francisco Bay during the summer of 1974 using a double settling tube device termed the “biosampler.” One tube of the device passively collected suspended sediments which settled from ambient waters at the sampling sites. The top of the second tube contained bay mussels (Mytilus edulis) as biological agents for the active entrapment and deposition of suspended particulates occurring in the water. Presence of the mussels in the sampler was, in most cases, indispensable for collection of sufficient amounts of material for analysis over one-week sampling periods.
A thin-layer chromatographic method was employed for analysis of total alkane and total aromatic hydrocarbons in recovered sediments. The sediments were found to contain 190–6188 ppm dry weight of total hydrocarbons, with alkane-aromatic ratios varying from 1.1 to 5.1. Water separated from recovered sediments after shaking contained from 15 to 450 ° per liter total hydrocarbons. Filtration of these water samples through 0.45 Millipore filters had little or no effect on their hydrocarbon concentration.
Calculations based on minimum possible values suggested that 13.5 or more metric tons of presumably pollutant hydrocarbons were present in association with suspended particulate matter in the bay system at any given time during the sampling period.
Previously published information on bay circulation suggested that suspended particulates, and thus pollutant hydrocarbons, may be accumulated in the shoal areas of the eastern bay margins.