Lead Contamination of the Elbe catchment via atmospheric deposition and overland transport over four decades (1958-1995)

Abstract

The neurotoxin lead has been emitted in large amounts into the environment over decades. To which extent this long-term pollution affects environmental systems is relatively unknown. Despite decreasing atmospheric pollution, soil and freshwater systems still indicate high lead concentrations. This study provides a first estimation of annual overland lead fluxes originating from atmospheric pollution in the Elbe basin in Central Europe during the period 1958-1995. The transport into aquatic systems of lead originally deposited in the soil is assessed. Three pathways from rural areas into the river system were considered: erosion, direct runoff and direct atmospheric deposition. For this purpose, a modified mesoscale empirical-conceptual model for heavy metal transport was applied. The results indicated that the total lead fluxes decreased after a peak in the 1970s. The emissions into the Elbe and its tributaries due to direct deposition showed a clear decline caused by decreasing atmospheric pollution since the 1970s. On the contrary, overland lead fluxes via erosion and direct runoff slightly increased. They were mostly influenced by the hydrometeorological and topographical conditions and less by the intensity of atmospheric input in a given year. Model results showed a steady background accumulation in the soils for the investigation period with a positive temporal and spatial correlation to atmospheric deposition. We conclude that lead control policies were only successful to a certain degree. In order to reduce pollution by highly sorptive, particle-bound substances such as lead, effort should not only focus on minimizing atmospheric emissions, but also on minimizing soil erosion.