Levels and long-term trends of polychlorinated biphenyls and DDT in mussels collected from the middle Adriatic coastal waters

Mussels were collected from several stations in middle Adriatic coastal waters during the period 1974 and 1990 and analysed for organochlorine content. Contaminant concentrations varied widely in samples collected at the same time from nearby stations. Total PCB and DDT mass fractions did not exhibit Gaussian distribution for area or collecting period, but logarithmic transformation of the data showed a significant relationship between area and mass fraction for both pollutants. DDT showed a seasonal change in concentration. There was a significant negative correlation between DDT mass fraction and collection time.