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 concentrations in surficial lake sediments in relation to atmospheric deposition. The study evaluates the application of sediment-water partitioning models at the field scale and finds optimum values for the partition coefficients. The impact of environment (sediment type, lake water pH, etc.) on K(D) values is explored directly by comparing K(D) estimates with environmental variables. K(D) values for each metal are found by optimising the fit between predicted and observed surface-sediment concentrations. The sensitivity of the 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), respectively, comparable to recent direct observations. Biogenic silica influenced 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, but higher than indicated by published experimental measurements. The results suggest that sediment-water partitioning models have an important contribution to make to field-scale lake studies of sediment heavy metals, and have important implications for palaeolimnological evaluations of heavy metal deposition.