Heavy metal concentrations in floodplain surface soils, Lahn River, Germany

Abstract

Even relatively pristine drainage basins in industrial countries would appear to have received anthropogenic inputs of heavy metals. Investigation of floodplain surface soils in the Lahn River drainage basin, west-central Germany, indicates that the Cu concentration is 1.5 times the pre-industrial level, Pb and Zn contents twice the pre-industrial level; Cd, Co, and Cr concentrations are nearly equal to background metal values. Based on contamination standards developed for the Lahn River, floodplain soils are moderately contaminated with Pb and Zn, slightly contaminated with Cu. Metal contents are uniform across the floodplain, with the exception of a peak immediately adjacent to the Lahn River. Floodplain surface soil metal contents are less in the Lahn River basin than in larger drainage systems of Germany. Although Lahn River metalliferous sediments are presently immobile, they would, if eroded, contribute to downstream heavy metal concentrations. Consequently, metal storage in smaller drainage basins such as the Lahn should be considered in predictions of future metal loads in major river systems, for aggregate small basins could serve as significant metal contributors.