Organochlorinated pesticides in sediments from the Lake Albufera of Valencia (Spain)

Bottom sediment samples from 121 sites of the Lake Albufera of Valencia were analyzed. Dieldrin, endrin, heptachlor and op′-DDT were not detected (<0.01 ng g^?1) in 88–93% of the sites. Aldrin and HCB concentration ranges were between <0.01 and 0.1 ng g^?1 in 86% and 94% of the sites, respectively. Heptachlor-epoxide and lindane 95% confidence intervals were 0.2–0.5 and 0.06–0.12, respectively. The greatest average concentration corresponds to pp′-DDE, pp′-DDD and pp′-DDT. The sum of six isomers and derivatives of the DDT average concentration reaches 2.1 ng g^?1, as opposed to 2.7 ng g^?1 for the sum of 13 pesticides considered. In the site with a major contamination, 27.0 ng g^?1 of pp′-DDD and 12.8 ng g^?1 of pp′-DDT were accumulated. The DDE:DDT proportion average was 0.37, indicating an aged DDT contamination. Concentrations of pesticides in sediments were compared to three sediment quality guidelines, and indicated that a low biological effects level can be expected in either sediments or aquatic organisms.