Uptake of cadmium, zinc, lead, and copper by earthworms near a zinc-smelting complex: influence of soil pH and organic matter.

Sampling was done largely in the Dutch Kempen region located south-east of Eindhoven and north to a complex of several large zinc smelting works. Some samples were taken about 10 km north to this region in order to include data on less polluted sites. All sites were situated in either grassland or heathland on sandy podzolic soil. Thirty-one sites were sampled in total, mainly along transects of 1 to 15 km from the nearest zinc smelter in a general north-south direction.