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 diff erent environmental compartments, the detailed environmental monitoring pre sented here focused on the mineralogical and chemical characterization of t he different waste materials, consisting of dumpings with ore fragments, fl otation tailings and medieval metallurgical slags. Leaching experiments wit h these materials, using eluents of different compositions and pHs were car ried out to assess the conditions governing the mobilization and re-fixatio n of these species. It was shown, that the carbonate host rock of the miner alization, the loess blanket covering the area and the organically rich mun icipal sewage sludges deposited on top of the tailings, represent potential barriers to the dispersion of toxic elements over a much larger area. More over, particulate emissions from the steep, unvegetated escarpments of the tailing heaps represent a continuous thread to the environment.