CYCLIC ORGANOCHLORINE COMPOUNDS IN REPRES ENTATIVE ORGANISMS OF THE BIOTA FROM THE VALDIVIA RIVER ESTUARY

A study was done of the bulk, the distribution and seasonal variation of the concentration of 22 cyclic organochlorines in whole soft tissue of five benthic species of the Valdivia river estuary (X Region, 39 d egrees 49'S, 73 degrees 18'W), using capillary gas chromatography-elec tron capture detector. Six seasonal sampling over a two year period al ong the river were done to conduct this research. Low levels of the or ganochlorine compounds, close to the range between the limit of detect ion and the limit of quantification (0,02 ng/g and 0.10 ng/g fora 10 g wet sample, respectively) were determined for most of the samples. In Hemigrapsus crenulatus and Cancer sp, the highest concentrations corr esponded to aldrin, 4,4'-DDE and decachlorobiphenyl (DCB) while in Chi lina ovalis the highest concentrations were due to heptachloro, aldrin , 4,4'-DDE and DCB. Mytilus chilensis showed heptachloro, aldrin, hept achloro epoxide, 4,4'-DDE and DCB and Tagelus dombeii showed aldrin an d DCB. The seasonal variation of the mean concentration of organochlor ines by sample followed the tendency of the seasonal variation of the lipid content.