The transport of heavy metals within a small urban catchment

A small urban catchment has been monitored for levels of Pb, Zn, Cd and Cu in the atmosphere, deposition, surface dust and stormwater runoff. The contribution of local emissions to total deposition is considered and found to be significant only for Zn. In rainfall, the metals are mainly particulate associated. Wet deposition is more important than dry deposition for Pb and Zn but the processes are comparable for Cd and Cu. The percentage of the dissolved metal level in rainfall which was observed in the storm runoff varied from 92% for Cu to 13% for Pb. A predictive model for metal concentration in runoff is presented and the results obtained for three monitored storms are assessed.