Transport of PCBs with leachate water from contaminated soil.

Natural soil contaminated with PCBs was used in this study. The soil was excavated from the area around the damaged capacitor of an electrical transformer station in Zadar (ETS 110/35 kV). A lysimeter experiment was conducted for 17 months under natural climatic conditions and designed to measure the concentration of PCB in the soil and leachates. Our research field was composed of four plots and there were three lysimeters on each plot. After 12 months, a negligible quantity of Aroclor 1248 (an average of 0.24%) and the Sigma 7 key PCB congeners (SigmaPCB(7); IUPAC No.: PCB 28, PCB 52, PCB 101, PCB 118, PCB 138, PCB 153 and PCB 180) were leached from the soils into the water collected under the lysimeters (an average of 0.32%). During two soil samplings, the soil was taken at three depths from each lysimeter. The distribution of Aroclor 1248 and 7 individual PCB congeners in the soil layers was determined before and after planting. Plot No. 1 had the highest percentage of contaminant removal after 12 months. The data indicate that the Sigma 7 key PCBs in the surface soil layers of all the plots decreased and the removal percentages ranged between 19.0% (Plot No. 2) and 47.6% (Plot No. 1). Volatilization from the soil surface may be the most important mechanism for the loss of these "more volatile" PCB congeners. The results showed an accumulation of PCBs in the deepest level of the soil plots, probably due to the vertical transfer of the PCBs and the lack of volatilization.