Publication Summary

High polychlorinated biphenyl (PCB) concentrations in Spokane River reservoir sediments are related to the type of particulate matter found in the sediment. Microscopical examination showed that the bulk of the organic matter was wood and plant material in varying states of decay. Also present in significant amounts were wood charcoal and partially carbonized plant material. The sediments were separated into charcoal, wood and silt/clay (<38 um) fractions and analyzed for PCBs.

High polychlorinated biphenyl (PCB) concentrations in Spokane River reservoir sediments are related to the type of particulate matter found in the sediment. Microscopical examination showed that the bulk of the organic matter was wood and plant material in varying states of decay. Also present in significant amounts were wood charcoal and partially carbonized plant material. The sediments were separated into charcoal, wood and silt/clay (<38 um) fractions and analyzed for PCBs.

Polychlorinated biphenyl analysis of the less than 38 micrometer fractions from each site and of the charcoal and wood fractions showed that the PCBs are concentrating in the wood and charcoal fractions. The wood and plant material contained higher levels of PCBs than the silt/clay (<38 um) fraction. The charcoal fraction contained significantly greater levels of PCBs and may be the primary component responsible for enrichment of PCBs.

The association of the PCBs with the charcoal fraction is logical when one recognizes the capacity for charcoal to absorb organic compounds. Apparently the reservoir location is acting as a sink for particulate matter. The concentration of PCBs in the organic particulate fraction may also increase the availability of the PCBs for recycling back to the biosphere as the organic matter is consumed or decays.