The distribution of mercury in the surficial sediments of the northern Tyrrhenian sea

Marine sediments are the ultimate recipient of mercury introduced into aquatic ecosystem either by man or by weathering. In the surficial sediments of the northern Tyrrhenian sea high concentrations of this metal were found in an area close to the effluent of a chlor-alkali plant and in the bays of La Spezia and Leghorn, which receive wastes from numerous industries and from port activities.The sediments of a much larger marine area off the mouths of the Ombrone, Albegna and Fiora rivers also contain high levels of Hg, part of which derives from the weathering of the rich cinnabar deposits of Mount Amiata and part from mining and processing the cinnabar.     

Toxicity of three oils to bivalve gametes and larvae

Water soluble extracts of three crude oils, Kuwait, Nigerian and Prudhoe Bay have been tested using the sperm and eggs of two marine bivalves. Fertilization is depressed and developmental abnormalities sometimes appear after exposure to these toxins. The spermatozoa, in particular, are very sensitive to the water-soluble fractions of these oils. Nigerian crude is particularly toxic.     

Influence of crude oil,derivatives and dispersants on larvae

Crude oils, oil derivatives and especially mixtures of oil and dispersant are harmful to larvae of some marine bivalve molluscs, but high concentrations are needed to cause death. Such high concentrations are unlikely to be reached in the open sea but are possible inshore or in estuaries which are the site of commercial shell-fisheries. The fact that spermatozoa are particularly sensitive to these compounds may have important consequences for the breeding success of contaminated bivalve populations.