Hydrogeochemical evaluation and nitrate-based non-carcinogenic health risk assessment of groundwater in the southern region of Jinan City, Northern China

Groundwater is a vital resource for ensuring ecosystem balance, urban water quality, and economic development. In this study, an integrated framework was applied to investigate groundwater hydrochemistry, identify its sources, evaluate the water quality, and assess the health risks associated with groundwater chemistry in the southern region of Jinan City (SRJC). The analysis combined mathematical statistics, positive matrix factorization (PMF), and Monte Carlo simulations (MCs). The mean total dissolved solids, total hardness, and pH were 551 mg/L, 412 mg/L, and 7.63, respectively, which confirmed the main property of weakly alkaline hard fresh water. The Ca 2+ and HCO 3 - ions played the dominant roles, and the Piper diagram presented that HCO 3 -Ca was the primary hydrochemical facies. The groundwater hydrochemistry in the SRJC was found to be governed by both natural processes, particularly hydro-rock interactions, and anthropogenic inputs, mainly agricultural activities and wastewater discharge. PMF resolved five major sources, among which carbonate weathering (39.5%) and wastewater/fertilizer inputs (20.1%) were dominant. Most groundwater samples were suitable for both domestic drinking and agricultural irrigation. Compared with simplified models and 1D-MCs, 2D-MCs provided a more robust risk assessment and revealed the possibility of risk underestimation by conventional approaches. The 2D-MCs-based non-carcinogenic risk assessment further showed a markedly higher risk for children (10.7%) than for adults (3.9%). • Natural and anthropogenic factors collectively govern hydrochemical characteristics. • 2. PMF、PCA and hydrochemical analyses revealed groundwater ion sources. • 3. Analysis using both the IWQI and CWQI reveals good water quality conditions. • 4.2D-MCs health risk simulation shows that children are more susceptible to NO 3 - hazards, and the model is more stable compared to 1D MCs.