Effect of organic carbon on the uptake of benzene vapor by soil

Abstract

Abstract Batch experiments were conducted to determine the uptake of benzene vapor by soils with difierent organic carbon content (foc), under benzene vapor concentration equal to that of vapor pressure. The time required to reach equilibrium increased with increasing foc and the sorbed equilibrium concentrations (qobs) were 0.44±0.2, 7.1±0.6, 12.3±0.8, 14.8±1.2, and 25.2±1.8 mg g‐1 for sand and soils with foc of 0.39%, 1.54%, 2.09%, and 4.15%, respectively. Vapor uptake due to mono‐layer surface coverage (qm) was less than 4% of qobs. The difference qobg‐qm normalized with respect to foc was several orders of magnitude higher than 20.2 mg g‐l reported for benzene vapor partitioning into soil humic acid, indicating that benzene uptake at saturated vapor pressure was mostly due to condensation rather than partitioning or monolayer sorption. These data would be applicable to soil in close proximity to liquid benzene, such as a spill or a leak.