Deposition fluxes of lead, cadmium, copper and polynuclear aromatic hydrocarbons (PAH) on the verges of a major highway.

Deposition fluxes of Pb, Cd, Cu and a range of 11 PAH compounds have been determined at distances of 3.8-220 m from the M6 motorway in northwest England over a period of 21 months. Considerable temporal variation is seen in the deposition fluxes, but time-averaged data show that fluxes of Cd, Cu and the PAH compounds are highly elevated close to the road, decreasing to background levels within 20-40 m. Whilst lead also shows considerable roadside enhancement, its deposition continues to decline over the full 220-m measurement interval. Background deposition levels for all pollutants measured are of the same order as other reported data. Analysis of deposition samples for organic compounds by gas chromatography-mass spectrometry revealed a wide range of mainly hydrocarbon compounds.