An assessment of the impact of solar degradation of polychlorinated biphenyls in the aquatic environment

The influence of solar radiation on the photochemical degradation of PCB under environmental conditions is investigated, and the extent to which this mechanism contributes to the elimination and possible detoxification of these compounds in the aquatic environment is estimated. For PCB in natural waters, amounts of the order of 10-1000 g per km2 might be transformed annually, and for shallow waters such as Erie lake up to 5 per cent of the lightly chlorinated PCB molecules might lose one atom of chlorine; while for highly chlorinated molecules, the rate of dechlorination would be considerably higher. Experimental data on the absorption spectra of PCB under laboratory conditions, and the intensity of incident and underwater radiation in the visible region are recorded for samples of lake water.