RELEASE OF CHEMICALS FROM CONTAMINATED SOILS

At sites that contain contaminated soils, there can be questions about the magnitude of risk posed by the chemicals in the soils and about t he cleanup levels that should be achieved. Knowledge about the rate of release of chemicals is important to answers to such questions. This article: (1) describes a laboratory protocol to obtain rate of release information for chemicals in soils, and (2) provides estimates of the rate of release of individual polyaromatic hydrocarbon (PAH) compound s from several manufactured gas plant (MGP) site soils. The data were analyzed using an empirical two-site model. Different fractions of PAH were released rapidly from these soils. For one soil, this fraction w as less than 20%, for others, the fraction ranged from 36 to 85%. The first-order rate constant (k2) of PAH released during the slow phase o f chemical release ranged from 0.0001 to 0.01 per hour.