Lack of an aging effect on the soil-air partitioning of polychlorinated biphenyls

Two different laboratory experiments were undertaken to investigate whether the aging of polychlorinated biphenyls (PCBs) in soils affects their soil-air partitioning behavior. In the first, portions of a sandy loam soil were spiked and stored in glass jars for 3-392 days to artificially age the PCB residues. Soil-air partition coefficients (K-SA) were then determined using a solid-phase fugacity meter. In the second experiment, a sewage sludge that had been highly contaminated with PCBs more than 30 years ago and stored in a lagoon was obtained and blended with soil. An additional 10 PCB congeners, which were shown not to be naturally present in the sludge-amended soil, were added. Aliquots of the spiked sludge-amended soil were stored for 1-42 days. After each storage period, the relative partitioning of the native and spiked congeners from the sludge-amended soil into the air was measured. Results from the two experiments showed that aging, by either storage in glass jars or exposure to natural processes in a lagoon for 30 years, did not affect the soil-air partitioning behavior of PCBs. There was a short period after spiking (2-12 weeks) in which the spiked PCBs were more readily partitioned into the air, but after this initial effect, there were no further changes in soil-air partitioning behavior.