THE USE OF MARINE BIVALVES IN HEAVY-METAL MONITORING NEAR VLADIVOSTOK, RUSSIA

The industrial and domestic wastes of Vladivostok, the biggest city in the Russian Far East, have led to the increasing pollution of neighbo uring coastal waters by heavy metals (Zn, Cn, Pb and Cd), The seasonal and spatial variability of Zn, Cu, Pb, and Cd concentrations in the c ommon molluscs Mizuchopecten yessoensis, Crenomytilus grayanus and Mod iolus kurilensis around Vladivostok were studied, There are large seas onal changes in the metal contents of the molluscs resulting from vari ations of filtration rate (for Zn and Cd) and differences in physiolog ical state (for Cn and Pb), For Modiolus kurilensis the change in tiss ue weight during the reproductive cycle is also significant. Simultane ous sampling during the summer showed that agreement between pollution levels in sediments and in tin molluscs was observed for Cu only, The Pb and Cd concentrations in molluscs reached maximum values in the ou ter zones of the polluted region, but Pb and Cd contents in the mollus cs decreased in the harbour localities where sediment metal loads indi cated heavy pollution. It is supposed that: in such localities with hi gh inputs of metals and organic substances, the molluscs may filter sm aller volumes of the contaminated water and thus accumulate smaller qu antities of metals.