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COMPARISON OF SOIL VOCS MEASURED BY SOIL GAS, HEATED HEADSPACE, AND METHANOL EXTRACTION TECHNIQUES
Citation:
Minnich, M. M., B. Schumacher, AND J. H. Zimmerman. COMPARISON OF SOIL VOCS MEASURED BY SOIL GAS, HEATED HEADSPACE, AND METHANOL EXTRACTION TECHNIQUES. Journal of Soil Contamination 6(2):187-203, (1997).
Description:
Comparsions of soil volatile organic compound (VOC) measurement techniques and soil properties expected to influence these measurements were performed at two dissimilar sites. A total of 41 soil gas, 52 heated headspace, and 51 methanol extraction/purge-and-trap measurements were obtained on collocated samples. Contaminants present at both sites included cis-1,2-dichloroethene, 1,1,1-trichloroethane, trichloroethene, and tetrachloroethene. Heated headspace offered the highest sensitivity, as indicated by the greatest percentage of detections per number of analyses. The statistical regression between headspace concentrations and methanol extraction concentrations was highly significant (p lt 0.001) with r-2=0.53. Headspace concentrations (range, 7 to 4250 ng/g) ran approximately 20 to 30% of the methanol extraction concentrations (range, 260 to 7300 ng/g), indicating that the methanol was able to extract significantly more of the chlorinated hydrocarons (CHCs) than the headspace extraction, even in soils with relatively low organic carbon contents (1t 0.25%). None of the soil properties (gravimetric moisture content, organic carbon content, percent sand, and percent clay) significantly improved the regression fit. The soil gas responses were unlike either headspace or methanol extraction data. CHC measurements by vapor extraction/soil gas could not be used to predict soil CHC concentrations at these sites.