Syracuse

Archive ouverte | Oceanologica Acta (0399-1784) (Gauthier-Villars), 1991 , Vol. 14 , N. 5 , P. 459-472

Pena, G | Picot, B

Edité par Gauthier-Villars

Analyses of mineralogy, granulometry and chemistry - aluminium,cadmium, chromium, copper, iron, lead, manganese, mercury, nickel, zinc, organic carbon, total nitrogen and phosphorus - are carried out in a Mediterranean lagoon: Etang de Thau. Shell-fish breeding and tourism make the Thau basin an important place for studying the impact of pollution within a lagoon environment. The spatial distribution of the metallic elements is related to the fine fraction (< 63-mu-m) and to the organic matter concentration of the sediment. Multivariate analysis gives a global picture of the incidence of micropolluants. It reveals a boarder zone poor in metals and organic matter which is greatly eroded by the bottom current. Several zones in the north and centre of the lagoon are highly contaminated areas with important organic matter and very fine particle content. Analyses of the two fractions of sediments - fraction below 2 mm and 63-mu-m - and depth profile studies demonstrate the natural origin of aluminium, chromium, iron, manganese, mercury and nickel, and the anthropic input of cadmium, copper. lead and zinc into the lagoon. The conclusion drawn is that monitoring and control of the quality of the sediment are important if the Thau lagoon is to remain a suitable area for shell-fish breeding.

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