Assessment of Ni phytomining potential in Ginigalpelessa serpentinite deposit, Southeast Sri Lanka

Nickel (Ni) phytomining is an emerging mining technique that uses hyperaccumulator plants to recover Ni from low-grade metal-rich soils such as serpentine. The Ginigalpelessa serpentinite deposit in Sri Lanka contains high concentrations of Ni, Cr, and Co where the phytomining potential is not well-documented. Therefore, the present study determines Ni, Cr, and Co contents in the soil and assesses the relationship between Ni content and plant diversity to identify potential areas for phytomining in the deposit. Thirty-one soil and twenty-five rock samples were collected from the deposit to analyze their metal contents. The abundant plant species were recorded at each location to analyze the plant diversity and species evenness using the Shannon Weiner Diversity Index. Based on soil analysis, Ni concentration in Ginigalpelessa serpentine soil ranged from 4,005 to 17,352 mg/kg which is within the range of global Ni phytomining grade (6,000 - 12,000 mg/kg). Moreover, areas having low diversity (0.0919 - 0.3061) showed high enrichment of Ni (7,000 - 12,000 mg/kg), emphasizing that low diversity areas with high Ni-enriched soils are suitable for in-situ Ni phytomining. However, further studies are required to assess the Ni hyperaccumulation ability of the abundant plant species to implement Ni phytomining in the Ginigalpelessa serpentinite deposit.