Recent dioxin levels in zone A of Seveso: northern part of the 'Bosco delle Querce' and the soil coverign the landfills 'Collina di Meda' and 'Collina di Seveso'

摘要

In order to avoid any risk associated with the reopening of the Bosco delle Querce to the public, the Fondazione Lombardia per l'Ambiente decided to investigate the present PCDD/F concentratiosn in the soil and the biota of this area. In 1995, soil sampling sites were selected according to the peak concentrations measured before the remediation of the area and the subdivision into two depths, 0-15 and 15-30 cm. Additionally, samples of conifer needles, leaves, grass, mushrooms, moss and earth worms were taken in 1994 and 1995. The samples were extracted in Soxhlet apparatus. The extraction was followed by a liquid chromatographic cleanup using an automated instrument from Fluid Management Systems. The measurements were made using a high resolution gaschromatograph (HP-5980) coupled with a double focusing high resolution sector field mass spectrometer (VG AUTOSPEC Ultima). All 2,3,7,8-substituted PCDD/Fs, including 2,3,7,8-TCDD, were analyzed and the toxicity equivalents (Int-TE) were calculated. Most of the soil measurements showed no great differences between topsoil and underlying soil. Generally the Int-TE levels in 32 soil samples were within the range of industrial regions not exceeding the concentration of 16 pg/g dry soil, and more than 70