Sustainable groundwater quality in southeast coastal Bangladesh: co-dispersions, sources, and probabilistic health risk assessment

Groundwater quality is a serious environmental concern that links to sustainable development in Bangladesh, particularly in the southeast coastal region to guarantee drinking water safety. Groundwater quality, co-dispersions, sources, and probabilistic health risk were assessed simultaneously using multiple approaches and indexes including the entropy water quality index, groundwater quality index (GWQI), Moran’s spatial autocorrelation index, fuzzy logic GIS, principal component analysis (PCA), the correlation matrix (CM), hazard index (HI), carcinogenic risk (CR), and stochastic uncertainty analysis. The average concentrations of EC (781.66 μS/cm), Mg2+ (40.75 mg/L), K + (11.96 mg/L), NO2− (3.57 mg/L), Fe (1950.76 μg/L), Mn (130.04 μg/L), Cd (1.75 μg/L) and Pb (42.22 μg/L) were identified in groundwater and surpassed the water quality limits from 25 to 100% based on the sampling sites. SO42−, NO2− and NO3− were the priority contributors affecting water quality degradation. Approximately 30 and 33% of samples were unfit for drinking use employing the EWQI and GWQI, respectively. Spatially, groundwater quality is degraded from southwest to northeast area inundating by saline water. PCA and CM disclosed that Fe, Mn, and Cu had geogenic origins from the dissolution of weathering and leaching; Pb and Zn were primarily from nonpoint sources; Cd, and As were dominated by the mixed sources. Based on the non-carcinogenic risk (NCR), the HI values were above the permissible limit (> 1) for both adults and children, except for a few sites, indicating harmful health risks on humans. The attribution of the analyzed metals did not outweigh the CR range (10–6–10–4) with an elevated risk of children. Uncertainty analysis identified As concentration, exposure duration, and exposure frequency as the most significant parameters affecting the probabilistic health risk results. The outcome of this study can provide the baseline data for sustainable groundwater management and human health protection in the coastal region.