engleski

Levels and long term trends of some high molecular chlorinated hydrocarbons in bivalves collected from the south Adriatic coastal waters

Numerous chlorinated insecticides and industrial chlorinated hydrocarbons are extremely resistant to degradation in the environment. The toxicological and other harmful effects of these compounds on an aquatic and terrestrial ecosystem have been well documented. The Adriatic Sea, as semienclosed 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 bivalves in the southern Adriatic coastal waters, Croatia was performed. Samples were collected between 1976 and 1990 at several stations located in the Adriatic coastal waters. It is very important to stress that all these samples were analyzed from a single analytical group (mostly by the same analyst), using a uniform methodology which was very successfully intercalibrated during seven international intercalibration exercises. Mass fractions of DDTs and PCBs in mussels ranged from ND (<0.1) to 172.4; in oysters from ND (<0.1) to 46.7 for DDTs and from ND (<0.5) to 467.2 in mussels and in oysters from ND (<0.5) to 113.1 x 10(9) wet weight for PCBs Total DDT and PCB mass fractions do not exhibit Gaussian distribution in the investigated area and collection period. This signifies that median and geometric means better indicate the central tendency of the investigated chlorinated hydrocarbon mass fractions than the arithmetic mean. Transforming the data to log values has the advantage of further normalizing the data, a prerequisite for the use of parametric statistics.

long term trends; chlorinated hydrocarbons; PCB; DDT; bivalves; Adriatic

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