A Technique for Hydrocarbon Soil Assessments in Katrina Impacted Areas and in other Large Site Characterization Programs

摘要

Government personnel and private property owners have analyzed hundreds of sediment and soil samples in areas impacted by Hurricane Katrina and thousands more analyses are likely in coming years. Outside of Katrina-impacted areas, hydrocarbon soil assessments are routinely performed at Superfund sites, during UST closures, at large and small DOD ranges, and at locations of fuel and chemical spills. Many of the quantitative and semi-quantitative assessment methods used in the field are expensive, require skilled technicians, or are time consuming. The objective of this research was to develop a soil field test for gasoline hydrocarbons that was inexpensive, easy to use, and provided same-day results. A battery-operated sampling pump was used to pull air through gasoline-contaminated soil samples held in small plastic cassettes. The air and hydrocarbon vapors were directed through glass detector tubes filled with color-changing adsorbents. In the detector tubes, hydrocarbon vapors convert chromic oxide [CrO3] coated on silica gel particles into chromium sulfate [Cr2(SO4)3], a conversion that changes the particles' color from orange to yellow-green. The length of color change is proportional to the mass of hydrocarbon vapors sampled. This technique had a limit of detection of 20 to 50 ppm by mass for gasoline hydrocarbons in soil and it was sensitive to fresh and 50% weathered gasoline. The technique had high precision, with a coefficient of variation of approximately 5% between tests. A cost analysis indicated that soils could be tested for less than