Geochemical variation between surface and subsurface soils and relationship to chronic kidney disease in North Central Province, Sri Lanka

Chronic kidney disease (CKD) in the North Central Province (NCP), Sri Lanka, is becoming a major cause of national burden with high mortality and morbidity. The origins of these kidney diseases are unknown, and the exact aetiology is not yet understood. Therefore, as an attempt to understand the effect of soil characteristics towards the disease, soil of surface (n = 25) and subsurface (50 cm depth, n = 25 of each) was collected from Horowpothana (HWP n = 50), Kabithigollawa (KBG n = 50), Medawachchiya (MWC n = 50) and Padaviya (PDW n = 50) of the NCP, where the highest number of patients is recorded. The soil samples were analysed using X-ray fluorescence for 22 major and trace elements, and the pH, electrical conductivity and oxygen reduction potential (ORP) for each sample were measured. The soil of all four villages mainly shows basic conditions. The high concentration of heavy mineral signatures in Horowpothana, Kabithigollawa, Padaviya and Medawachchiya could relate to high CKD patients in these four areas. The 50-cm soils of all four areas are in oxidized condition, while surface soil is in the anoxic condition. High fluctuation between surface and 50 cm may indicate high mobility of ions. According to the current study, P, F- and Fe2O3 ion could easily be mobilized into the groundwater of the area and thereby be related to the highest recorded CKD patients in these areas. Thus, as for the current study the heavy metals and elements that indicate the variations which causes health issues are Fe2O3, Pb, Zn, Cr, F-, Ti, Cu, Ni, V and Zr.