Mercury Accumulation in the Mussel Mytilus Galloprovincialis, and the Flat Head Grey Mullet Mugil Cephalus, the White Seabream Diplodus Sargus Fish, in the Coast of the Wilaya of Big Casablanca at the Atlantic Site of Morocco

摘要

This study was conducted to evaluate the Mercury (Hg) contamination along the coastline of the Wilaya of Big Casablanca. It investigated the spatio- temporal variation of Hg concentrations in the mussel, Mytilus galloprovincialis, at eight sampling stations, over a period from summer of 1998 to spring of 2002. The maximum Hg concentration measured in the mussel tissue during this study was 7.73 μg/g dry weight. This concentration was measured in a mussel collected near an electrolysis and petrochemical company. Seasonal variations of Hg concentration were evident in the form of an increase during the winter and spring, and a decrease during the summer and autumn. Study of the mussel's organotropism showed that Hg was preferentially accumulated in the viscera. In addition, the Hg concentration increased with the size of the mussel. The mussels were grouped into two sizes, big (～ 5-7 cm), and small (～ 3-5 cm), with respective mean concentrations of 1.05 and 0.40 μg/g dry weights. Hg concentrations, measured in two species of fish that represent a significant source of food for the local population, the flat head grey mullet Mugil cephalus, and the white seabream (Diplodus sargus), had stet means of 0.44 and 0.24 μg/g dry weight. There are lower than the concentrations measured in previous studies in so-called polluted regions throughout the world, and the limit of 0.5 μg/g fresh weight Hg, fixed by the European Commission and the National Inter-Ministerial Commission (Circulaire conjointe, 2001; CEE, 2001 and 2002.).