Organochlorine pesticides and PCBs in a southern Atlantic coastal lagoon watershed, Argentina

There recently have been increasing interest in South America on organic po llutants from the coastal marine environment. This study intended to seek o ut the occurrence and distribution of persistent organochlorine compounds i n the Mar Chiquita coastal lagoon watershed. The levels were measured in se diments and associated crabs. Though a significant number of PCBs (mainly p enta- and hexachlorinated congeners) were detected, the concentrations were very low (in the order of ppbs), indicative of an estuarine environment wi th little industrial development. On the other hand, pesticide residues wer e higher than PCBs in one or two orders of magnitude, as a result of the im portant agricultural activities in the area. Heptachlor epoxide, DDT and it s metabolites, and gamma -HCH were the predominant OC pesticides in sedimen ts as well as in crabs. Significant differences among geographical areas: C hannel 5 and Vivorata Creek (northern and southern sampling sites, respecti vely) contained detectable pesticide concentrations (heptachlor epoxide, DD E, DDD, and mirex).