Groundwater vulnerability to arsenic in semi-arid region of Pakistan: Sources identification, spatial analysis, and public health risks evaluation

The persistence of arsenic (As) contamination in aquifers poses a significant environmental and public health risk in Pakistan, driven by both natural geochemical processes and anthropogenic activities. This research focused on the groundwater of Matiari District, Sindh, Pakistan, by analyzing 52 drinking groundwater samples to evaluate hydrogeochemical characteristics and arsenic contamination, with implications for public health risks, focusing on their behavior, occurrence, and distribution patterns in the semi-arid region. Hydrochemical facies results depicted that groundwater belongs to mixed CaMg-Cl and CaMg-HCO 3 − types. Gibbs plots indicated that water chemistry is primarily governed by rock–water interactions, with minimal influence from evaporation. Principal Component Analysis identified that nearly 80% of the variability in water chemistry could be attributed to both anthropogenic and geogenic sources. Based on the Water Quality Index, 8% of the water samples were deemed unsuitable for drinking. Moreover, 12% were identified as very poor quality, and 15% were categorized as poor. Arsenic levels ranged from 5 to 250 µg/L, averaging 41 µg/L. Alarmingly, 24% of the samples surpassed the drinking level of 10 µg/L established by the World Health Organization, highlighting a significant public health. However, exposure risk assessment revealed significant health concerns from As-contaminated water, with maximum HQ of 9.99 for children and 1.27 for adults, and maximum CR of 3.00 × 10⁻³ for children and 3.81 × 10⁻⁴ for adults. The findings underscore the urgent necessity for detailed arsenic monitoring and the implementation of effective mitigation strategies to reduce exposure. Addressing arsenic contamination is vital to safeguarding public health, as the current levels pose a substantial risk of cancer and other arsenic-related health issues within the affected communities.