Passive sampling is a well-known method of sampling water, air and soil gas. Adsorbent-based passive samplers effectively collect volatile organic contaminants due to the concentration gradient that the sampler establishes when exposed to contaminated media. VOCs diffuse from areas of higher concentration to the relatively low concentration surface of the sampler. Samplers collect a mass of contaminant at a rate that is directly related to the concentration that the sampler is exposed to. In air and water, the rate of collection is directly measurable. Due to the heterogeneity of soil and the variability of air-filled interconnected pores, however, uptake rates in soil must be determined using indirect means.
groundwater passive samplers, concentration values
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