Distribution of Trace Metals in Sediments and the Relationship with their Accumulation in Earthworms

Abstract

Concentrations of Cd, Pb, Cu and Zn and their speciation in river sediments (Guadalquivir River, Spain), were determined. Relationships between trace metal concentrations in sediments and earthworms were studied in order to estimate the rate at which metals accumulated in organisms living in sediments.

The bioavailable fraction of Cd represented more than 50 % of the total Cd found in sediments, and this percentage was much greater than those of the other elements examined. Most of the Cu was present in the organic and residual fractions. Lead and Zn were mainly associated with the crystalline iron oxide fraction.

The application of factorial analysis to the total heavy metal concentrations and some soil properties reduced the number of original variables to only three, namely factors, which explained the total variance of 94 %.

Metals accumulated in earthworms were related by a second grade polynomial equation with fractions where the metals were mainly bound. Cd exhibited the highest accumulation factor, followed by Zn, Pb, and Cu, respectively.

Key Words:

• Heavy metal speciation
• Cd
• Cu
• Pb
• Zn
• sediments
• earthworms
• factorial analysis
• regression