The fate of major constituents and chromium and other trace elements when acid waters from the derelict Libiola mine (Italy) are mixed with stream waters

Geochemical modeling was used to investigate the fate of major constituents and Cr and other trace elements when acid waters from the derelict Libiola mine are mixed with the Gromolo creek waters, and related processes. This was carried out in two steps: (1) Mixing between acid waters and stream waters was simulated using the EQ3/6 software package; the results showed that mixing brings about the precipitation of some secondary solid phases, mainly a ferrihydrite-rich solid mixture of hydroxides and basaluminite. (2) The sorption of cations (Cr3+, Cu2+, Zn2+, Mn2+, Ni2+, Ca2+, and Mg2+) and anions (image and image) on ferrihydrite was modeled by means of the code MINTEQA2, treating the concentrations of relevant solutes and the moles of ferrihydrite (computed by means of EQ3/6) as input data.