Groundwater quality evaluation and health risk assessment in coastal lowland areas of the Mekong Delta, Vietnam

This study provides a comprehensive assessment of groundwater quality in the Mekong Delta (Vietnam) and their potential risks to human health. The dataset consists of 282 groundwater samples collected in dry and rainy seasons between 2017 and 2018. Multiple physio-chemical parameters, groundwater quality index (GWQI), and irrigation water quality indices (IWQI) were employed to evaluate the suitability of groundwater resources for drinking and irrigation purposes. Thereupon, the hazard quotient (HQ), and total hazard index (HI) were used to assess the non-carcinogenic risks to different demographic groups. GWQI indicates that groundwater samples are excellent (41.5%), good (40.4%), poor (17%), and very poor (1.1%) classes for drinking purpose. The total hazard index (HI) indicated that 15.2%, 8.5%, 7.4%, and 7.1% of samples express non-carcinogenic health threats to infants, females, children, and males. Irrigation water quality indices (IWQI), namely, EC, sodium adsorption ratio (SAR), residual sodium bicarbonate (RSBC), soluble sodium percent (SSP), permeability index (PI), and magnesium hazard (MH), reveal that 82.2%, 94%, 20.2%, 69.6%, 45.4% and 12.8% of samples have EC < 2250 μS/cm, SAR <26, RSBC <1.25, SSP <60%, PI > 75%, and MH < 50%, respectively, which are suitable for irrigation use. Wilcox diagram shows that 17.54% of total groundwater samples exceed the permissible levels of salt-tolerant crops and solidity hazards in the study area. Furthermore, high concentrations of nitrate (>50 mg/L) and chloride (>1000 mg/L) were detected in the shallow, intermediate, and deep aquifers. GWQI and IWQ maps imply that groundwater in the South-western area is suitable, whereas groundwater in the central area is not recommended for any purpose. These findings provide useful insights into the vulnerable groundwater system of the coastal lowland area of the Mekong Delta related to human activities (agricultural practices, dam construction) and global climate change impacts. Accordingly, appropriate management strategies for water resources and mitigation solutions are imperatively needed to ensure the sustainability of the groundwater resource and the protection of public health in the Mekong Delta.