Abstract
ABSTRACT
In the evaluation of hazardous waste sites, soil gas sampling for volatile compounds can be used to delineate the extent of underground contamination. Methods for sampling soil gas generally involve active extraction of soil gas samples or passively collecting the contaminant with adsorbents. This paper describes a set of experiments to evaluate the 3M badge passive soil gas sampler. Each trial in this set of experiments consisted of exposing 3M badge samplers to soil gas of known hexane or toluene concentration for defined periods of time. The experiments were divided into two phases. Phase I consisted of nine trials for each contaminant. Each trial had a different integrated exposure (1 to 7000 ppm•days) at a soil moisture 10% and mean temperature of 23 °C). Phase II consisted of three trials for each contaminant. Integrated exposure and temperature (mean of 23 °C) were kept relatively constant and soil moisture (approximately 1%, 10% and 14% by weight) was changed. In general, the response of the 3M badge sampler increased with increasing exposure over the entire integrated exposure range for both hexane and toluene. Pearson r = 0.87 (p<0.001) for hexane and 0.90 (p<0.001) for toluene. The samplers showed possible saturation at exposures above 2500 ppm•days for hexane and 7000 ppm•days for toluene. All of the 3M badges showed much lower contaminant adsorption than was predicted by theoretical calculation. 3M badge samplers exposed under low soil moisture conditions adsorbed 1.5-3 times more hexane or toluene than badges exposed at higher soil moistures.
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