Heavy metals in organisms from the northern Tyrrhenian sea.

The concentrations of zinc, manganese, copper, cadmium, lead and mercury have been determined in soft tissues of four marine organisms (Mytilus galloprovincialis Lmk., Nephrops norvegicus L., Mullus barbatus L., Engraulis encrasicolus L.) collected seasonally from the winter of 1976 to the spring of 1980 in various areas of the Tyrrhenian Sea (western Mediterranean). In all four species levels of all metals, except mercury in all areas are alike while mercury levels vary and, furthermore, are higher than in specimens from other areas of the Mediterranean and also from other seas. The possible natural origin of the mercury from cinnabar (HgS) ore as well as the suitability of the four species as bioindicators is discussed.