In a previous study, remediation of anthracene from soil was faster in the top 0-2 cm layer than in the lower soil layers. It was not clear whether this faster decrease was due to biotic or abiotic processes. Anthracene-contaminated soil columns were covered with black or transparent perforated polyethylene so that aeration occurred but that fluctuations in water content were minimal and light could reach (LIGHT treatment) or not reach the soil surface (DARK treatment), or left uncovered so that soil water content fluctuate and light reached the soil surface (OPEN treatment). The amount of anthracene, microbial biomass C, and microbial activity as reflected by the amount of CO2 produced within 3 days were determined in the 0-2 cm, 2-8 cm, and 8-15 cm layer after 0, 3, 7, 14, and 28 days. In the 0-2 cm layer of the OPEN treatment, 17% anthracene remained, 48% in the LIGHT treatment and 61% in the DARK treatment after 28 days. In the 2-8 cm and 8-15 cm layer, treatment had no significant effect on the dissipation of anthracene from soil after 14 and 28 days. It was found that light and fluctuations in water content stimulated the removal of anthracene from the top 0-2 cm soil layer, but not from the lower soil layers. It can be speculated that covering contaminated soil or pilling it up will inhibit the dissipation of the contaminant. [ABSTRACT FROM AUTHOR]