Heavy metal migration in soil. An experimental evaluation at two metal recycling industries

摘要

Laboratory and field investigations were made at two metal recycling sites in order to evaluate the risk of heavy metal migration to groundwater. The top soils at both sites contained very high concentrations of lead, copper, and zinc, high concentrations of nickel, cadmium, and chromium and somewhat elevated concentrations of many other metals. Investigations focused on lead, copper, and zinc. The leachate from soils representing different metal recycling activities at the sites (scrap cutting, car-battery destruction, cable burning, and general activities including storage) as obtained from column leaching test in the laboratory showed in most cases only slightly elevated concentrations of dissolved metals (< 10 times) as compared to the leachates from uncontaminated reference soils. Soil and soil water sampled at several profiles at the two metal recycling sites confirmed the indications obtained from the leaching tests: The metals had migrated less than 0.5 m below the surface during approximately 25 years of activity at the sites, except at the car-battery destruction locations. The investigation concludes that the risk of metal migration to the groundwater is limited as long as pH stays high in the top soils containing very high metal concentrations. The now abandoned car-battery destruction directly on the ground surface has lead to very high concentrations of metals in the soil and migration of metals that may affect the groundwater. However, the extend of the metal plume in the groundwater was not investigated. (EG)