INSITU DETERMINATION OF PCB CONGENER-SPECIFIC 1ST ORDER ABSORPTION DESORPTION RATE CONSTANTS USING CHIRONOMUS-TENTANS LARVAE (INSECTA, DIPTERA, CHIRONOMIDAE)

The uptake of polychlorinated biphenyl (PCB) congeners was measured in the larvae of a laboratory-reared chironomid midge, Chironomus tentans, placed in the upper Hudson river, New York during 2 months in 1985. This procedure was investigated as a method for determining water congener concentrations during times of fluctuating PCB levels, and to model uptake of PCBs by river biota. After a 96 h exposure period, total PCB concentrations in the test organisms averaged 6.7 μmgg-1 total PCBs, compared with water concentrations of 67 ng 1-1 (mean value for both months). Uptake and elimination constants, time to equilibrium and concentration factors were calculated for each of 21 selected congeners. Analysis of PCB congeners in insects harvested at intervals during the 96 h period showed that uptake differs with varying degrees of chlorination relative to water concentrations. At the end of the exposure period, concentration factors ranged from 4000 to over 300,000 times the water concentrations. Differences in the replicate indicate potential problems with this method as a field tool; instead of using all congeners separated in analysis, several individual congeners should be selected for use based on their importance to the river fauna and the consistency with which they are analyzed. © 1990.