POLYCHLORINATED-BIPHENYLS (PCBS) IN BULK SOIL AND PARTICLE-SIZE SEPARATES OF SOILS IN A RURAL-COMMUNITY

In a rural community (Stephanskirchen, Southern Germany) situated near a waste incineration plant six A horizons were sampled to determine 1 4 polychlorinated biphenyls (PCBs) in bulk soil and particle size sepa rates (clay, silt, fine and coarse sand) and to test the suitability o f alkaline saponification for PCB extraction. The PCB concentrations w ere higher in alkaline saponification extracts than in Soxhlet extract s. However, the extraction efficiency of up to fourfold chlorinated PC Bs was lower and more than sevenfold chlorinated PCBs were destroyed. Nevertheless, alkaline saponification was suitable to determine the in dicator congeners 28, 52, 101, 138, 152, and 180. The sum of the PCB c oncentrations ranged from 8.4 to 59.5 mu g kg(-1) which was as high as in soils of big cities. However, the concentrations did not reach the threshold value for agricultural purposes of 200 mu g kg(-1) gs propo sed in Literature for the sum of the six indicator congeners. The hexa chlorinated PCBs 138 and 153 mere the most abundant (together > 50% in all samples) whereas PCB 1 could not be detected in any sample. On th e average, PCB concentrations increased as particle size decreased. Wh en normalized to C-org, however, the line sand fraction; had the highe st PCB concentrations. A slight decrease of lower chlorinated PCBs as particle size decreased indicated an increasing state of degradation. The PCB compositions in the emissions of a comparable waste incinerati on plant (Bamberg, Bavaria) and in Stephanskirchen soils differed mark edly. Therefore, we did not get any indications that waste incineratio n was a main source of PCBs in the examined soils. Instead, higher chl orinated technical PCB mixtures such as Clophen A 60 or Aroclor 1260 m ay be the most important sources.