Predicting heavy metal concentrations in the surface sediments of Norwegian headwater lakes from atmospheric deposition: An application of a simple sediment-water partitioning model

Data from 96 headwater lakes from Norway are used to model heavy metal conc entrations in surficial lake sediments in relation to atmospheric depositio n. The study evaluates the application of sediment-water partitioning model s at the field scale and finds optimum values for the partition coefficient s. The impact of environment (sediment type, lake water pH, etc.) on K-D va lues is explored directly by comparing K-D estimates with environmental var iables. K-D values for each metal are found by optimising the fit between p redicted and observed surface-sediment concentrations. The sensitivity of t he K-D estimates to data structure is examined by bootstrapping. K-D values of 10(5.8) and 10(6.2) were calculated for cadmium (Cd) and lead (Pb), res pectively, comparable to recent direct observations. Biogenic silica influe nced K-D values for Cd, Pb and Zn, whereas lake depth influenced Pb. pH did not have any detectable effect. K-D for zinc (Zn) was less well defined, b ut higher than indicated by published experimental measurements. The result s suggest that sediment-water partitioning models have an important contrib ution to make to field-scale lake studies of sediment heavy metals, and hav e important implications for palaeolimnological evaluations of heavy metal deposition.