Tracing the origin of chromium in groundwater. Current and new perspectives

Abstract In this review study, the current and new perspectives in tracing the origin of chromium in groundwater are reviewed. Emphasis is given on the role of fertilizers on the elevated groundwater concentrations of Cr(VI) in ultramafic environments and on the isotope approach in evaluating groundwater contamination by Cr(VI). Phosphorous-bearing fertilizers with high Cr content could be a significant anthropogenic source of Cr(III) in soils and, consequently of Cr(VI) if an oxidizing agent is present. They may also cause anionic Cr(VI) desorption from the iron oxide surfaces by simultaneous PO43- adsorption. Nitrogen-bearing fertilizers are responsible for nitrification, subsequent soil acidification, and increase in the dissolution of Cr-bearing minerals. So far, chromium isotopes that are commonly used to distinguish between geogenic and anthropogenic contamination and to monitor the natural attenuation of Cr(VI) indicate the need for a more systematic research on the Cr isotope fractionation in natural and in any anthropogenic Cr-bearing formations.