Cd and Zn concentrations in small mammals and willow leaves on disposal facilities for dredged material

Disposal sites for dredged material are often polluted with heavy metals. T he uptake of Cd and Zn by small mammals and willow trees was assessed on th ree sites with a different pollution degree. Detailed soil sampling showed a huge variation in soil characteristics within the sites, typical for disp osal sites for dredged material. This variation made risk assessment and in terpretation of soil chemical analyses complicated. Small mammals were thou ght to give a more integral description of the contaminant level because th ey cover a large area. Cd concentrations in small mammals were elevated com pared with background levels whereas Zn concentrations were rather low. The re were no significant differences between sites in Cd or Zn levels in anim als. Leaf analysis showed a clear response to the pollution degree of the s ites. The calculations using the BIOMAG model indicated that the Cd of the soil caused low risk for predators. However, the elevated Cd and Zn concent rations in the willow leaves on the polluted sites and the high Cd concentr ations in the small mammals on all sites indicated that ecosystem developme nt should be carefully considered. (C) 2001 Elsevier Science Ltd. All right s reserved.