Modelling the Concentration and Deposition of Heavy Metals in the UK

A relatively simple Lagrangian atmospheric transport model (FRAME) was adapted to simulate the concentration and deposition of nine heavy metals (As, Cd, Cr, Cu, Pb, Ni, Se, V and Zn) in the UK. The modelled data was compared with annually averaged measured wet deposition of metals and concentrations in air. The model obtained good correlation with measurements of metal concentrations in air but with very large underestimates (normalised mean biases in the range -0.64 to -0.93), indicating a major under-estimate in total atmospheric emissions. Wet deposition was less closely correlated to measurements. Inclusion of estimates of spatial re-suspension of wind-driven dust for the UK in the model simulation led to an improvement in agreement with measured concentrations. However the amount of re-suspended material was considered to be highly uncertain due to the limited availability of measurement data of the heavy metal content of surface soil and dust.