Modelling of soil contamination by airborne lead and cadmium around several emission sources

A survey was made of the concentration of total cadmium and lead in the topsoil at 125 sites surrounding several emission sources in northern France; one of the most important lead-zinc smelters in Europe was among those sources. A non-linear regression model was evaluated for a single emission source. The concentrations of both metals in soil were almost proportional to the inverse of the distance from the source and to the square root of the wind frequency. As several pollution sources were present in the area, an additive linear model was tested and a satisfactory adequacy between predicted and observed values was obtained. Thus, it was possible to draw a precise mapping of isoconcentration contour plots for both pollutants and to estimate the total burden of lead and cadmium in the topsoil of that area, as well as the relative contribution of each source to the global pollution. It was also possible to give guidelines for a more adequate sampling design.