Abstract
In August 1998 monitoring of throughfall, bulk precipitation and runoff started at two sites in the Netherlands to determine the loads of heavy metals to the verge of motorways. The research was carried out during one year. Strong seasonal variation was found in runoff with highest fluxes in winter. Throughfall measurements showed an exponential decrease of fluxes downwind of the motorways. After about 30 m from the road fluxes dropped to background values, A sound wall at one of the sites had a clear effect on the deposition gradient. Directly behind the wall deposition was much lower and nearly reached background values. Concentrations in the top layer of the soil showed a clear gradient, becoming smaller deeper into the soil. (A)