Origin of Cr in Alluvial and Aeolian Sediments and Ultramafic Rocks in Sultanate of Oman: Magnetic Fractionation and Sunlight Effect

The changing climatic conditions are imposing a vital re-consideration on the hydro-chemical pathways for contaminants. The circumference Mediterranean countries will be possibly under imminent water stress. The present study attempts to identify the sources and the leaching capacity of Cr(VI) in a coastal alluvial fan and aeolian soil and in a serpentine soil in an area offering an aridity analogue, like Oman. Magnetic separation and different leaching media were applied along with Cr(VI) sorption experiments in daylight (open air) and in laboratory conditions (without direct sunlight). In most of the samples the released Cr(VI) concentration was higher that the drinking water standard (50 μg L⁻¹). Magnetic soil fraction has the highest bulk Cr concentration, however, the leaching of Cr with phosphate extraction solution was high in the no-magnetic fraction. Immobilization of Cr(VI) was higher in the sunlight conditions for the serpentine soil and not for the alluvial/aeolian soils.