Integrating pollution indices and multivariate statistics to assess heavy and trace element contamination and human health risks in a tropical coal mining region.

Heavy and trace elements (HTEs), including Aluminium (Al), molybdenum (Mo), rubidium (Rb), strontium (Sr), titanium (Ti), barium (Ba), gallium (Ga), tin (Sn), and vanadium (V) are naturally present in the Earth's crust; however, their concentrations in soils may increase in areas affected by intensive mining activities. This study investigated the distribution of these HTEs in soils collected at increasing distances (20, 50, 300, and 700 m) from an open-cast coal mine in the Mahanadi Coalfields Limited (MCL), Talcher, Odisha, India, at two soil depths (0-15 and 15-30 cm). Soil contamination was evaluated using the contamination factor (Cf) and geo-accumulation index (Igeo), while ecological and human health risks were assessed using standard risk assessment approaches. The contamination indices generally decreased with increasing distance from the mine, indicating a spatial pattern of relative enrichment. Among the investigated elements, Sn and Ga exhibited the highest relative enrichment with respect to the selected local background, whereas the interpretation of Al and Ti was made cautiously because of their predominantly lithogenic origin. Multivariate statistical analyses (PCA and HCA) identified distinct associations among trace elements, suggesting the combined influence of natural geological factors and possible mining-related inputs. Human health risk assessment indicated that soil ingestion was the dominant exposure pathway, with children exhibiting higher average daily intake (ADI), hazard quotient (HQ), and hazard index (HI) values than adults. Vanadium contributed most to the non-carcinogenic risk through ingestion and dermal exposure, whereas Al was the major contributor through inhalation. Overall, the study provides baseline information on the distribution, relative enrichment, ecological risk, and screening-level human health risks of HTEs in soils of the Talcher coalfield and supports future environmental monitoring and detailed source apportionment studies.