Polychlorinated biphenyls (PCBs) and organochlorine pesticides (OCPs) in the sediments of an Italian drinking water reservoir.

The concentration of 9 polychlorinated biphenyls (PCB 28, 52, 101, 151, 153, 170, 180, 183 and 194) and of 6 micropollutants commonly classified as organochlorine pesticides, or OCPs (alpha-HCH, beta-HCH, gamma-HCH, p,p'-DDT, p,p'-DDE and p,p'-DDD), was determined in 22 sediment samples of lake Simbirizzi, an artificial reservoir supplying drinking water to the city of Cagliari (Sardinia, Italy). The quantification was performed by analysing purified sediment extract with HRGC-ECD. The average concentrations proved to be relatively low. In the case of p,p'-DDE, the contaminant with the highest concentration, a mean value of 0.84 ppb (micrograms/kg d.m.) was found. These relatively low concentrations and the comparison with data relating to other lakes suggest that, as far as PCBs and the majority of OCPs are considered, atmospheric inputs are likely to be the main source of contamination. Only for lindane (gamma-HCH) it is possible to assume a contribution from agricultural activities. The presence of its isomers (alpha-HCH and beta-HCH) was attributed to natural occurring reactions of the gamma-form.