LEVELS AND SOURCES OF PCDDS AND PCDFS IN URBAN BRITISH SOILS

Soil samples from five British cities have been analysed for PCDDs and PCDFs. Mean concentrations for PCDD and PCDF congeners were: TCDD, 65 ng Kg-1; PeCDD, 69 ng Kg-1; HxCDD, 154 ng Kg-1; HpCDD, 817 ng Kg-1; OCDD, 9980 ng Kg-1; TCDF, 232 ng Kg-1; PeCDF, 189 ng Kg-1; HpCDF, 156 ng Kg-1; HpCDF, 152 ng Kg-1; and OCDF, 196 ng Kg-1. The mean levels for urban samples are significantly higher (p < 0.01) than rural and semi-urban samples previously reported. Principal component analysis of isomer distributions for urban samples and those of known origin indicate that combustion processes are the principal source of PCDDs and PCDFs in these soils.