ATMOSPHERIC DISPERSION AND PHYSICOCHEMICAL BEHAVIOR OF CD AND PB IN RAINWATER AFTER EMISSION BY A LEAD WORKS

Here we report the atmospheric dispersion and physicochemical behaviou r of Cd and Pb after emission from the lead works at Stolberg-Binsfeld hammer, Germany. Measurements of wet deposition were made with rain sa mplers between Stolberg and the town of Julich to the north-east durin g the period August 1991-May 1992. Analysis of rainwater after filtrat ion in the rain sampler comprised heavy metal concentrations in the re sidue as well as heavy metal in the filtrate. Conclusions were drawn f rom the regional distribution of deposition data and statistical facto r analysis. Experimental results on deposition show that in the case o f Pb, wet deposition by particulate matter prevails for the emittent a t Stolberg-Binsfeldhammer as far as the station at Stolberg-Werth. In the case of Cd, deposition of Cd dissolved in rainwater dominates. Cad mium and Pb compounds analyzed have total concentrations in the rain s ampler which are smaller than their respective solubilities. It is con cluded that in the stationary state, Cd and Pb must have an insoluble status on the particulate matter. In the case of Pb, elemental Pb coul d also be responsible for the relatively large amount of Pb adsorbed o n solid particles. From the relative contribution of metal deposition on particulate matter and in filtered rainwater in the vicinity of the emitter, there were higher dispersion rates of the particulate matter studied in comparison with the heavy metal species in filtered rainwa ter. Statistical factor analysis of Cd and Pb wet deposition in the re gion investigated revealed the ranking of the influencing factors as: particulate matter dispersion and scavenging, rainfall conditions, dis persion of heavy metals dissolved in rainwater as well as emission of heavy metals. Factor analysis of metal concentrations in the residue a nd proton concentration in the filtrate showed the course of the metal dissolution process throughout dispersion.