Sediments contamination levels of organochlorine pesticides in Weihe River, Northwestern China

The residual levels of hexachlorocyclohexanes (HCHs), chlordane (CHL), and dichlorodiphenyl trichloroethanes (DDTs) in surficial sediments at 18 sites along 6 typical monitoring sections of the Weihe River, in Northwestern China were investigated. The concentration ranges were 0.087–0.61 ng g−1 for HCHs, 0.10–0.28 ng g−1 for CHL, and 0.030–0.10 ng g−1 for DDTs, respectively. Molecular markers (the concentration ratios of OCPs to their degradation products and the relative contents of the different components of OCPs) suggested that lindane-type HCHs might have been used in or around the Weihe River basin, and there still exists a new pollutant input. DDTs in the Weihe River sediments came from both industrial DDT and dicofol; the industrial DDT made the greatest contribution to total DDTs. The OCPs concentration was negatively correlated with the logarithmic value of annual average flow volume along the six sections, over the years 2006–2009. The potential ecological risk arising from the presence of OCPs was minimal, but their potential harm to human health cannot be ignored due to their accumulative effect through the food chain.