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

It is well documented that synthetic chlorinated hydrocarbon residues are widespread through the oceanic ecosystem. The Adriatic Sea, as a semi-enclosed body of water, is of special interest for an evaluation of the entry, extent and fate of the pollution by chlorinated hydrocarbons. An investigation of levels of chlorinated hydrocarbons in mussels in the eastern Adriatic coastal waters, off Croatia was performed. Samples were collected between 1972 and 1992 at a large number of stations. All these samples were analyzed by a single analytical group (mostly by the same analyst), using a uniform methodology which inter calibrated during seven international inter-calibration exercises. Mass fractions of chlorinated insecticides and polychlorinated biphenyls in mussels ranged from ND (<0.1) to 107.3 for DDTʹs and from ND (<0.5) to 1072 × 109 wet weight for PCBs and from 19 to 35,600 for DDTʹs and from 52 to 103.000 × 109 on an extracted organic matter basis. Averages and ranges of chlorinated hydrocarbons mass fractions in mussels from the Adriatic are compared with the data of mussels obtained in other Mediterranean areas. In all four investigated areas of the Mediterranean (II, IV, VI, and VIII) DDT total mass fractions in mussel are higher than those for the Adriatic. In areas (II, IV, and VIII) the PCB values are higher compared to the Adriatic. Linear regression analysis of pollutant mass fractions in the mussel samples from the eastern Adriatic coastal waters collected during the 20-year period with the years of collection show that a statistically significant negative correlation coefficient is obtained by comparing the values of total DDT mass fractions. For PCBs, a slight negative correlation coefficient is obtained but it is not statistically significant. In the Pula area this correlation coefficient is positive, but it is also statistically non-significant.