Geochemical modeling as a tool to investigate chromium contamination in groundwater

The geochemical modeling is an essential tool to understand the water-rock interaction processes. In this work has been used the reaction path modelling to investigate the release and fate of geogenic Cr in ophiolitic Italian areas. During the water-rock interaction the geogenic trivalent Cr hosted in Cr-bearing minerals (serpentine minerals, spinels, pyroxene, etc.) of serpentinites rocks is oxidized in Cr (VI) highly mobile and toxic, resulting largely dangerous for environment and human health. Although generally accepted hypothesis is that geogenic Cr(III) oxidation is driven by the reduction of trivalent and tetravalent Mn, we performed a modeling varying Fe2O3/(FeO+Fe2O3) weight ratios considering the trivalent Fe the only oxidant present in suitable amounts in serpentinite rock. Indeed , the amount of Mn in studied serpentinites rocks is very low. The reaction paths reproduces the analytical concentrations of relevant solutes, including Cr(VI), in the Mg-HCO3 groundwater hosted in the ophiolitic aquifers of Italy. Although others investigation are need, this result is a new perspective to understand well the environmental issue of Cr-rich groundwater of worldwide.