Published By US Fish and Wildlife Service, Department of the Interior
Issued over 9 years ago
Summary
Description
An investigation was made into chemical contamination at 26 National Wildlife Refuges in the Lower Mississippi River Ecosystem. Samples of water, sediment, and fish were collected, and passive sampling devices that accumulate persistent organic chemicals were deployed. Residues of currentuse pesticides CUPs, organochlorine pesticides OCPs, polychlorinated biphenyls PCBs, polycyclic aromatic hydrocarbons PAHs, and mercury Hg were measured along with limited toxicity testing and exposure biomarkers. Organochlorine pesticides were detected at every refuge, and total DDT and toxaphene exceed published levels for the protection of fish or wildlife at nearly half the refuges. Currentuse pesticides were detected at every refuge, but at only onehalf the frequency as nearby offrefuge areas. Mixtures of multiple pesticides were often detected and their detection frequency was clearly associated with their use and persistence. About 25 of the refuges contained pesticides at concentrations exceeding aquaticlife criteria and over 65 ofthe offrefuge sites exceeded criteria. Concentrations of PCBs were low throughout the region, with no evidence of potential for adverse biological effects. Concentrations of PAHs were low throughout the region, except near oil and gas production facilities were very high concentrations caused I 00 mortality in sediment pore water toxicity tests. Concentrations of Hg in sediment and fish were generally below levels of concern. Overall, there was strong evidence that over onehalf of the refuges are experiencing meaningful adverse biological effects from chemical contamination.