Seasonal variation of heavy metals (Cd, Pb and Hg) in sediments and in mullet, Mugil cephalus (Mugilidae), from the Ghar El Melh Lagoon (Tunisia)

Abstract

1 - This study investigates the toxic contaminants cadmium (Cd), lead (Pb) and mercury (Hg) in surface sediments and in the fish species Mugil cephalus of the lagoon of Ghar El Melh (GEM), Tunisia. 2 - Sampling was conducted seasonally during 2003 and 2004. The results of this study indicated that levels of Cd and Pb varied in sediment from 0.4 to 0.9µgg-1dw and 25 to 70µgg-1dw, respectively. Mercury concentrations in sediment were generally below 1µgg-1dw. The highest level was observed in the north-east of lagoon. In fish muscle, concentrations of Cd, Pb and Hg varied between 0.013 to 0.025µgg-1dw, 0.048 to 0.422µgg-1dw and 0.222 to 0.409µgg-1dw, respectively. 3 - Results of heavy metal analyses in sediment and fish indicated that there were relatively metal contamination problems in GEM lagoon near the harbour due to the anthropogenic activities, notably from the Medjerda River and wastewater from the coastal towns around the lagoon.