Geochemical evidence for the accumulation of vanadium in soils of chronic kidney disease areas in Sri Lanka

Abstract

Chronic kidney disease (CKD) is a major health problem in the dry zone of Sri Lanka. Although the precise figures are not known, number of patients suffering from CKD has reached a crisis level during the last decade. This study describes soil geochemistry of the affected region to establish the etiology for the unresolved problem of CKD. A field survey was carried out in 88 localities, and concentrations of 16 major and trace elements from soil samples were determined using X-ray fluorescence spectroscopy. It was revealed that the number of CKD patients is high where elevated concentrations of soil vanadium were observed. Further, V levels in nonagricultural soils of CKD-reported sites have significantly exceeded the risk level (200 mg/kg) given by the Canadian Environmental Council. The strong enrichment of V in soil indicates that its bioavailable fraction is also high. Besides the V of soils studied, Fe and Cr contents are also contained to be high. However, the values have not reached up to the threshold levels. Moreover, the presence of lower concentrations of other harmful trace elements (F, As, Pb, Zn, Cu and Ni) in the hotspots does not exhibit a significant impact on CKD. Strong positive correlations of V with Fe, Cr, Ti and Ni indicate that they may have derived from mineral phases of weathered basement rocks. Further, ratios of the immobile trace elements in soils studied illustrate that V is mainly derived from parent meta-igneous rocks of basaltic composition.