Persistent organochlorine pesticides in sediments of three coastal lakes and one Andean lake in central Chile

We have measured concentrations and distribution of Persistent Organic Comp ounds (POC) in sediment cores from four Chilean lakes: Laguna Chica de San Pedro, Laguna Grande de San Pedro, Lieu-lieu, and Icalma. The organochlorin e compounds were extracted with n-hexane in a soxhlet system and then ident ified and quantified by gas chromatography using a Ni-63 Electron Capture D etector. Statistical analyses were performed using a Principal Components A nalysis (PCA) and the Pearson Correlation. The following pesticides were identified in the sediments: a-HCH, Lindane, Heptachlor, Aldrin, pp ' -DDT, pp ' -DDE, and pp ' -DDD. The results show v ariation in both POC distribution and concentration when comparing pristine and urban lakes. It is important to note that pp ' -DDE (range: b.d.l. - 1 .68 ng g(-1) d.w.) and pp ' -DDT (range: b.d.l. -0.89 ng g-1 d.w.) were pre sent in three of the four lakes in the study. The statistical analyses show ed significant correlations between pp ' -DDE and pp ' -DDD. Correlations b etween pp ' -DDT and its metabolites were not detected. The PCA showed grou pings of some of the organic compounds based on concentration and degradati on over time. It is concluded that Laguna Chica de San Pedro is the lake wi th the highest concentration of POC's, although the levels appear low when compared with those measured in pristine areas in Southern Chile.