CADMIUM, ZINC AND TOTAL MERCURY LEVELS IN THE TISSUES OF SEVERAL FISHSPECIES FROM LA-PLATA RIVER ESTUARY, ARGENTINA

A survey of the concentrations of heavy metals - cadmium, zinc and tot al mercury - in the tissues of fifteen fish species from Samborombon B ay, La Plata river estuary, in Argentina, has been carried out. Liver appeared to be the main organ accumulating cadmium and zinc, while bot h liver and muscle showed a similar ability for accumulating mercury. The bioaccumulation process was verified for the three metals analyzed , even though low concentrations have been determined. The biomagnific ation process of the metals studied was not verified in this environme nt. The highest metal concentrations were recorded in Mugil liza, and particulate matter and sediments - which are closely related to its tr ophic and ecological habits - seemed to be the main source of metals f or this species. Both Micropogonias furnieri and Mugil liza were recog nized as possible indicator species for future monitoring programmes f or heavy metals in Samborombon Bay. Considering the present results, t his area of La Plata river estuary is characterized as a non-polluted environment.