Detection of Persistent Organic Pollutants in the Mississippi Delta Using Semipermeable Membrane Devices

Abstract

Persistent organic pollutants (POPs) are hazardous chemicals, with moderate to low volatility, that resist degradation and tend to accumulate in living tissues. Their persistence in various media facilitates their transport over long distances to remote regions where they have never been used. They have been found to present risks to human health and the environment in polar and other regions. In February 1997, a United Nations Environmental Program Governing Council Decision identified 12 persistent organic pollutants (aldrin, chlordane, DDT, dieldrin, dioxins, endrin, furans, heptachlor, hexachlorobenzene, polychlorinated biphenyls, mirex, and toxaphene) for which international action was deemed necessary to protect human health and the environment. Semipermeable membrane devices (SPMDs) are passive sampling devices designed to sample POPs. They consist of a low-density polyethylene (LDPE) lay-flat membrane filled with 1 gram of a high molecular weight lipid, triolein, that cannot diffuse through the membrane. When placed in an aquatic environment, SPMDs passively accumulate hydrophobic organic compounds. The LDPE tubing mimics a biological membrane in its ability to allow selective diffusion of organic compounds. After the deployment period, SPMDs are retrieved from the stream, dialyzed, cleaned up with gel permeation chromatography and silica gel, and analyzed using gas chromatography/mass spectrometry (GC/MS). From SPMDs placed in five Mississippi Delta streams, the POPs DDT, endrin, dieldrin, and toxaphene were detected. In addition, two insecticides still in use, the organophosphate chlorpyriphos and the organochlorine endosulfan, were detected. Two low-solubility herbicides not commonly detected in surface water, pendimethalin and trifluralin, also were detected.

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Zimmerman, L.R., Thurman, E.M., and Bastian, K.C., 1999, Detection of persistent organic pollutants in the Mississippi Delta using semipermeable membrane devices, in Daniel, B.J., ed., Proceedings of the Twenty-Ninth Mississippi Water Resources Conference, April 7-8, 1999, Raymond, Mississippi: Mississippi State, Mississippi Water Resources Research Institute, p. 97-109.

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