DESIGN AND EVALUATION OF A LONG-TERM SOIL GAS FLUX SAMPLER

The development and evaluation of a device for measuring soil-air fluxes of organic contaminants is presented. The sampler is deployed at the ground surface and measures fluxes coming to the surface by using a passive sampling element. A computer model is used to aid the design and calibration of the sampler. Laboratory tests of prototype samplers are used to verify the model and to determine the accuracy and precision of measurements. Several field demonstrations are conducted in which results are compared to conventional measurement approaches. Measurements were obtained at fuel-contaminated soils near a leaking underground storage tank and at a land treatment unit for refinery wastes. Long-term fluxes estimated using the passive sampler closely matched results obtained by a series of emission isolation flux chamber measurements. The passive sampler offers several advantages as compared to other measurement approaches. It is considerably simpler to use and more cost-effective than active samplers, yet may offer comparable performance in many environments.