The budget of lead, copper and cadmium for a major highway.

Data on deposition fluxes and concentrations of lead, cadmium and copper in road drainage water at proximate sites on the M6 motorway in northwest England have been analysed. The integration of fluxes over a year indicates that metal removal in road drainage water exceeds that deposited on the roadside verges, most markedly in the case of copper. From estimates of the source strength for lead, it is concluded that approximately 90% of emissions are dispersed by the atmosphere away from the immediate vicinity of the road. These findings are supported by estimation of integrated deposition since the opening of the road, derived from analysis of roadside soils.