Soil and groundwater contamination with heavy metals at two scrap iron andmetal recycling facilities

Field studies were performed at two actual scrap iron and metal recycling f acilities in order to evaluate the extent of heavy metal migration into sub soil and groundwater caused by mon than 25 years of handling scrap directly on the ground without any measures to prevent leaching. Surface soil sampl es, called 'scrap dirt', representing the different activities on the two r ecycling facilities, all showed very high concentrations of lead (Pb), copp er (Cu) and zinc (Zn), high concentrations of cadmium (Cd), chromium (Cr) a nd nickel (Ni) and somewhat elevated concentrations of many other metals. I n particular high concentrations were found for Ph at the car battery salva ge locations (13 to 26 g Ph kg(-1)) and Cu at the cable burning location (2 2 g Cu kg(-1)) at one site. The migration of metals below the surface in ge neral (except at the car-battery salvage locations) was very limited even a fter approximately 25 years of activity. Soil and soil water profiles all s howed elevated concentrations in the upper 40 cm but below this depth the s oil concentrations as well as the soil water concentrations of metals were comparable with the concentrations found in uncontaminated reference profil es. The retention of the metals in the upper part of the profile was suppos edly due to sorption as well as precipitation processes. At one site the me tals had migrated to 80 cm depth at the car battery salvage location and at the other site with coarse sandy subsoils, elevated concentrations of ph, Zn, and Cd were found in the groundwater 3 m below the ground surface. In t he unsaturated soil, FH had decreased to about 3.5, facilitating the migrat ion of the metals. This low FH value was presumably caused by the acids fro m the car batteries. The investigation concluded that the risk of metal mig ration to the groundwater is limited as long as FH stays high (above pH 6.5 ) in the top soils containing very high metal concentrations. The now aband oned car battery salvage operated directly on the ground surface has led to very high concentrations of metals in the soil and migration of metals tha t may affect the groundwater. However, the extent of the metal plume in the groundwater was not investigated.