Extractability and mobility of heavy metals in Flanders sediments

For many years, wastes from industries and households were disposed into rivers and canals of Flanders. Sediments are dredged from canals, Scheldt and Leie rivers and disposed into open lands.The study was conducted to assess the extractability and bioavailability of Cd and Pb by using HCl and the chelating agent EDTA as single extractants. Total metal contents were measured using aqua regia digestion.Soil physico chemical properties were considered.The mobility of Cd and Pb in both contaminated sediments and non-contaminated soils were discussed. In all extractants the proportion of extractability of Cd and Pb was higher in the contaminated dredged sediment derived soils than non-contaminated soils. Regardless of soils and extractants, relative extractability was higher for Cd as compared to Pb. This may imply the more availability of Cd than Pb.The use of 0.5 mole/Liter HCl may be recommended for first level screening of soil contamination of heavy metals. EDTA (0.05 mole/Liter) was believed to provide a better assessment of bioavailable/mobile metals content in soils than 0.5 mole/Liter HCl extractant. However, 0.5 mole/Liter HCl mobilized Cd and Pb irrespective of soil types.