Characteristics of DDTs in fish from Lake Taihu: an indicator of continual DDTs input in China.

Four typical freshwater fish species in Lake Taihu (TH), China, were collected and analyzed for the residue levels of DDT and its metabolites DDD and DDE (sum of o,p'- and p,p'-DDT, DDD, and DDE is designated as DDTs). The DDTs concentrations ranged from 3.24 to 37.1 ng/g, and p,p'-DDE was the dominant isomer, followed by p,p'-DDD and o,p'-DDT. Source identification indicated that DDTs in TH was mostly stemmed from the historical usage of technical DDT mixture, but a new source of DDT, i.e., dicofol-type DDT, also occurred. The results from the present work, together with previously published data, clearly indicate that dicofol-type DDT was widespread and was an important continual source of DDTs in China.