Polyethylene-membrane passive-vapor-diffusion samplers, or PVD samplers, have been shown to be an effective and economical reconnaissance tool for detecting and identifying volatile organic compounds (VOCs) in bottom sediments of surface-water bodies in areas of ground-water discharge. The PVD samplers consist of an empty glass vial enclosed in two layers of polyethylene membrane tubing. When samplers are placed in contaminated sediments, the air in the vial equilibrates with VOCs in pore water. Analysis of the vapor indicates the presence or absence of VOCs and the likely magnitude of concentrations in pore water.
Examples of applications at nine hazardous-waste sites in New England demonstrate the utility of PVD samplers in a variety of hydrologic settings, including rivers, streams, ponds, wetlands, and coastal shorelines. Results of PVD sampling at these sites have confirmed the presence and refined the extent of VOC-contaminated ground-water-discharge areas where contaminated ground water is known, and identified areas of VOC-contaminated ground-water discharge where ground-water contamination was previously unknown. The principal VOCs detected were chlorinated and petroleum hydrocarbons. Vapor concentrations in samplers range from not detected to more than 1,000,000 parts per billion by volume. These results provided insights about contaminant distributions and ground-water-flow patterns in discharge areas, and have guided the design of focused characterization activities.
