Trace metal contamination in core sediments of Pandharabodi Lake, Central India: eco-environmental implications

Freshwater lakes in central India like Pandharabodi Lake (PBL), face escalating environmental pressures due to anthropogenic activities, threatening their ecological conditions. Despite growing concerns, systematic investigations on trace metal pollution in the PBL sediments are so far not done, hindering effective conservation strategies. The present study aims to evaluate temporal distribution, enrichment, and potential eco-environmental risks of 14 trace metals (Al, Fe, Mn, Zn, Cu, Cr, Ni, Pb, Co, U, V, Rb, Th, and Sc) in the PBL core sediments. A sediment core from the deepest part of the PBL along with 06 soil samples around the lake was collected and analyzed for trace metal concentrations using X-ray fluorescence (XRF) technique. The metal pollution was assessed using enrichment factor (EF), Index of geo-accumulation (I_geo), contamination factor (CF), ecological risk factor (E_r), potential ecological risk index (PERI), and multivariate statistical analyses. The geochemical study of trace metals in the vertical profile, pollution indices, and statistical assessment revealed low to moderate pollution in the core sediments of the lake. The highest contamination factor (CF) values were observed at 8 cm core depth for Cu indicating "considerable pollution", while Fe, Mn, Al, Co, Cr, V, Zn, Ni, and Sc show "moderate pollution". The maximum enrichment factor (EF) values were recorded at 32 cm core depth for Rb and at 24 cm for U indicating "moderate enrichment". The mean geo-accummulation index (I_geo) values for Cu show that the PBL core sediments had "low level of pollution" by Cu, while remaining metals show the unpolluted nature of sediments. The estimated potential ecological risk index (PERI) showed "low potential risk" for aquatic organisms and plants due to its low value (< 150), i.e., < 66.80 in 100% of samples in consideration of eco-environmental risk. The principal component analysis (PCA)/factor analysis (FA), correlation coefficients, and hierarchical cluster analysis (HCA) showed that Cu had considerable contamination in the PBL core sediments due to anthropogenic activities like particulate matters released from adjoining iron and steel plant and opencast coal mine in addition to its origin from the geogenic (natural) sources like weathering and erosion of basalts and soils present in the catchment area. The present findings provide valuable insights for policymakers, contributing to the development of effective conservation strategies for freshwater lakes in central India and other tropical regions.