Soil monitoring in the vicinity of a municipal solid waste incinerator: Temporal variation of PCDD/Fs

To determine the temporal variation in the levels of polychlorinated dibenzo-p-dioxins (PCDDs) and dibenzofurans (PCDFs) in soils in the vicinity of a municipal solid waste incinerator (MSWI), 24 soil samples were collected at the same points in which samples had been taken one year before. In the previous survey, PCDD/F concentrations ranged from 0.22 to 5.80 ng I-TEQ/kg (dry matter) with median and mean values of 0.80 and 1.08 ng I-TEQ/kg (dry matter), respectively. In the present survey, PCDD/F levels ranged from 0.11 to 3.88 ng I-TEQ/kg (dry matter) with a median value of 0.88 ng I-TEQ/kg (dry matter) and a mean value of 1.17 ng I-TEQ/kg (dry matter). It means an increase of 8.3% in the mean PCDD/F levels during the last year. In turn, the mean PCDD/PCDF ratios were 0.62 (previous survey) and 0.55 (current survey), respectively. A comparison of the increases in the quantities of PCDD/Fs found in soils with those estimated according calculations suggests that no remarkable sources of PCDD/F emissions other than the MSWI are present in the area here examined. The differences between the current results and those found in 1996 could be explained by the heterogeneity of the samples.