Potentially toxic element contamination in earth material and wild flora at the Roşia Montană ancient mining area (Romania)

Potentially Toxic Element (PTE) pollution from mining activities is a significant environmental problem, as mine dumps are source of heavy metal dispersion in the nearby ecosystems. In this work PTE contamination in the mining area of Roşia Montană (Romania) was investigated by bio-geochemical analyses that have affected both the Hop waste-rock dump and the valley of Roşia River. The Roşia Montană hydrothermal ore deposit is hosted in andesites and dacites of Neogene age piercing the prevolcanic sedimentary basement as breccia pipes. They host polymetallic sulphides and Au-Ag-Te mineralizations that present in epithermal veins, mineralizing phreatomagmatic breccias and stockworks (WALLIER et al., 2006). On the Hop waste dump (2.5 ha) 10 plant samples, belonging to Salix spp., Popolus tremula and Betula pendula species, were collected with the corresponding rizosphera. Moreover, other 12 mixed soil and plant samples, belonging to Alnus glutinosa, were collected, starting from the adit of the SF. Cruci din Orlea gallery up to the confluence between Roşia and Abrud Rivers. Results show that the plant species growing on the Hop waste-rock dump can tolerate acid substrates, with pH values ranging from 3 to 5. Results appear interesting for phytoremediation purpose, also for the surrounding areas still not vegetated. On the other hand, they highlight that ecotoxic elements are actually moving from substrates to living beings, resulting in a potential geochemical hazard.