MICROBIAL DEGRADATION OF POLYCHLORINATED BIPHENYLS IN SOIL

Abstract

Removal of PCB-containing sediment (includes Aroclors 1248, 1254, and 1260) from a contaminated pond and placement on land have been suggested to prevent continued pollution of the Housatonic River system in Connecticut. To test if soils differed in their ability to degrade PCBs, we incubated the contaminated pond sediment in shake culture with eight agricultural or forest soils. The rate and degree of degradation of Aroclors 1248, 1254, and 1260 present in the sediment were followed over a 112-d period. All soils but one degraded Aroclor 1248 at least 70% in 14 d and over 90% in 112 d. Aroclor 1254 was degraded by only three soils and a pine litter. The rate of degradation of Aroclor 1254 was much slower than that of Aroclor 1248, and only about 40% of 1254 was degraded in 112 d. Aroclor 1260 was not degraded by any soil sample. As the growth of aerobic organisms in the shake cultures increased, degradation of Aroclor 1248 also increased in parallel. The number of organisms in the shake cultures that were able to use Aroclor 1221 as a carbon source reached a peak at 70 d, indicating a lag of growth of Aroclor-degrading organisms. The use of certain agricultural soils for disposal of PCB-containing sediments may have limitations.