Dioxinegehalten in grond van weilanden in de omgeving van de afvalverbrandingsinstallatie te Zaandam

Abstract

This report describes the results of analyses of dioxin levels in soil of five pastures in the vicinity of the municipal waste incinerator of Zaandam. Isomer specific analysis of dioxins were conducted by high resolution gas chromatography-mass spectrometry using a polar chromatographic capillary column. Dioxin levels are expressed in toxic equivalence per kg of dry soil, per kg of organic carbon as well as per unit of volume of soil using the international toxicity equivalence factors (ITEF) of individual congeners. Samples consisted of blends of frequent samplings of five pastures in the layer at 0-2 cm and 2-10 cm, respectively and of two pastures also in the layer at 10-50 cm below the surface. Dioxin levels in the layer of 10 - 50 cm were 2 and 5 ng/kg dry soil, respectively. Levels in the layer of 2-10 cm were between 12 and 48 ng TEQ/kg dry soil and in the surface layer of 0-2 cm between 13 and 252 ng TEQ/kg dry soil. The lower surface values (13, 60 and 82 ng TEQ/kg dry soil) correspond to pastures located close (<500 m) to the MSW near or inside the wet deposition region of the incinerator. The value of 13 ng TEQ/kg dry soil in the surface layer corresponds to a pasture, of which the soil has been mechanically treated in 1989. High values in the surface layer (207 and 252 ng TEQ/kg dry soil) were found in pastures located near the maximum dry deposition region at larger distances to the MSW (>1000 m North East). Estimates based on dioxin levels in soil of dioxin deposition during the entire life time of the installation indicate average rates of approx. 300 ng/m2/y if no degradation of dioxins in soil is assumed to 430 ng/m2/y when a half life of dioxins in soil of 10 y is assumed. These values are 2-8 fold higher compared to calculated deposition rates using results of a recent emission measurement of the MSW.<br>