Legacy persistent organic pollutants in Mytilus galloprovincialis from the Sochi River estuary (Russian black sea coast): A mussel watch monitoring study.

This study presents current data on POP levels in the soft tissues of Mytilus galloprovincialis from the Sochi River estuary on the Russian Black Sea coast. Our results revealed a predominance of degradation products (β-HCH, DDE, and DDD), indicating the long-term environmental persistence of these substances. However, the presence of parent pesticide compounds (lindane, o,p'-DDT, and p,p'-DDT) in some samples could suggest a possible recent local influx. Among PCBs, highly chlorinated congeners (PCBs 118, 153, and 138) were prevalent, implying a historical contribution of these xenobiotics. Significant intersex differences in ∑PCB accumulation were found, with males accumulating higher levels than females, which may be attributed to reproductive traits and the elimination of lipophilic compounds with gametes. An inverse relationship between mussel shell size and ∑PCB tissue concentrations was established, attributable to the growth dilution effect in actively growing young individuals. A comparative analysis showed that current POP levels in the study area are lower than the historical maxima recorded in the Black Sea in the late 20th century. However, the contaminant profile, characterized by a high proportion of HCH isomers, differs from those typical of other contemporary Black Sea studies (e.g., in Bulgaria and Turkey), where DDT metabolites dominate. This mixed profile shows a qualitative resemblance to findings from some developing nations in the Asia-Pacific region, although cross-study comparisons are complicated by methodological differences. These findings underscore the necessity for further monitoring of POPs in this area and highlight the need for wider spatial surveys along the Russian Black Sea coast.