Environmental monitoring of heavy metals and arsenic from Ag-Pb-Zn mining: a case study over two millennia.

2000 years of mining activity at Wiesloch, Germany left behind a legacy of mining wastes, some of which have extremely high contents of toxic elements like As, Cd, Tl, Sb, Pb and Zn. To evaluate their long-term impact on different environmental compartments, the detailed environmental monitoring presented here focused on the mineralogical and chemical characterization of the different waste materials, consisting of dumpings with ore fragments, flotation tailings and medieval metallurgical slags. Leaching experiments with these materials, using eluents of different compositions and pHs were carried out to assess the conditions governing the mobilization and re-fixation of these species. It was shown, that the carbonate host rock of the mineralization, the loess blanket covering the area and the organically rich municipal sewage sludges deposited on top of the tailings, represent potential barriers to the dispersion of toxic elements over a much larger area. Moreover, particulate emissions from the steep, unvegetated escarpments of the tailing heaps represent a continuous thread to the environment.