Heavy metal pollution in northwestern Himalayan groundwater: comprehensive assessment using multiple pollution indices and Monte Carlo simulation for health risk

The ecosystem and human health are seriously at risk from contamination of heavy metals in water. A variety of pollution indices are used in this study to analyze the presence of heavy metal contamination in groundwater and used Monte Carlo simulation to quantify the health hazards associated with it. In two seasons the pre-monsoon and post-monsoon groundwater samples were taken in triplicate from 25 sites in South Kashmir, which is situated in the southern portion of the northwest Himalayas. The research area had higher than average quantities of heavy metals, according to the results. The cold climate probably had no seasonal influence on groundwater quality, but concentrations were generally greater in pre-monsoon than in the post-monsoon. To evaluate contamination, the study employed the following pollution indices: NPI (80%), HEI (76%), MI (80%), CoD (76%), and HPI (0%). There were found to be strong correlations between these indices, with R² values of 0.96, 0.94, 0.96, and 0.95 between HEI and HPI, HEI and MI, HEI and Cd, and HEI and NPI, among other high correlations. The results of the Monte Carlo simulation for many exposure pathways showed that youngsters had a greater 95th percentile of carcinogenic risk than adults. The heavy metals were graded according to their non-carcinogenic risk using the Hazard Index (HI) as follows: Pb > Ni > Mn > Cd > Cu > Fe > Zn. For adults, the non-carcinogenic risk was shown to be 4.92E-01, while for children, it was 1.41E+01. Human health risk evaluations also showed that youngsters had a greater overall cancer risk (OCR) (1.61E-01) than adults (4.74E-03). PRACTITIONER POINTS: Groundwater Quality Monitoring: The study highlights the critical need for regular groundwater quality monitoring, particularly in areas prone to heavy metal contamination, like South Kashmir. This is essential for the early detection of hazardous metal levels and the mitigation of public health risks. Use of Pollution Indices: Pollution indices such as NPI, HEI, MI, and CoD can be effective tools for assessing and quantifying heavy metal contamination in water sources, providing a comprehensive understanding of the contamination levels. Health Risk Assessment: Monte Carlo simulations for human health risk assessments underscore the importance of prioritizing children's health, as they are at greater risk of carcinogenic and non-carcinogenic effects from heavy metal exposure. Seasonal Impact on Contamination: While seasonal variations in groundwater quality were not significant due to the cold climate, higher contamination levels were detected during the pre-monsoon period. This indicates the need for heightened monitoring before monsoon seasons in similar climatic regions.