EFFECTS OF SEWAGE SLUDGES CONTAMINATED WITH POLYCHLORINATED DIBENZO-P-DIOXINS, DIBENZOFURANS, AND BIPHENYLS ON AGRICULTURAL SOILS

The fate of polychlorinated dibenzo-p-dioxins (PCDDs), polychlorinated dibenzofurans (PCDFs), and polychlorinated biphenyls (PCBs) in sewage sludges after agricultural application was analyzed. This study was b ased on the experiments designed for two soils with different agronomi cal characteristics after applying different rates of sewage sludge. T he concentrations of PCDDs, PCDFs, and PCBs in soils were determined b efore and after the application of sewage sludges, and a general incre ase was observed with the applied rate, especially in the case of the PCDDs. The values of sludge-treated areas were 1.2-11.6 times higher t han the respective values of the noncontaminated areas. Changes observ ed in the ratio between PCDD and PCDF levels and in the isomeric distr ibution also suggest the influence of the sewage sludge on the soil. T he values of sludge-treated areas were compared with the limits propos ed in Germany for agricultural and horticultural land uses. The result s of the soil investigation showed that, in the case of an initial soi l with low contamination, the final soil did not exceed the limit; but , in the case of an initial soil with considerable contamination, the final soil exceed the limit, which restricts the cultivation of certai n vegetables.