Geochemical distribution of selected elements in serpentinite deposit in ginigalpelessa, Sri Lanka

Abstract

Serpentinite deposits are well known for their natural enrichments of heavy metals (Ni, Cr, Co) and depletions of macro nutrients (Ca, Mg), which have caused different ecological and health impacts in the surrounding areas. In addition, they are considered as potential sources for rare earth elements (REEs). While Ginigalpelessa, the largest serpentinite deposit in Sri Lanka, has been the focus of several toxicological studies, to date, there have been no significant studies related to geochemical distribution of heavy metals, macro nutrients, and REEs in the deposit. Therefore, the present study is focused on the assessment of geochemical distribution of selected elements (Ni, Cr, Co, Ca, Mg, and REEs) in the deposit. Accordingly, concentrations of these elements in 30 rock and soil samples were analyzed and their geochemical distributions were studied using the results of the present study and literature. Ni (6629 ppm) and Cr (35875 ppm) showed the highest enrichments in the deposit, whereas all the studied heavy metals have exceeded the permissible levels of the World Health Organization. In addition, a low Ca/Mg ratio was observed in the deposit, which explains the inhibition of plant growth in the deposit. Moreover, the identified areas with high enrichments of Ni, Cr, and Co using the prepared geochemical distribution maps will be useful in the spot remediation for toxicity in the deposit. Since serpentine soil is recognized as a low-grade source for Ni, low-grade extraction techniques such as phytomining and bioleaching are recommended to extract valuable metals from the Ginigalpelessa deposit.