Seasonal hydrochemical characteristics of spring water in Southern Poland: integrating geochemical modeling, health risk analysis and mitigation strategies

This study investigates seasonal hydrochemical characteristics of spring water at six sites in southern Poland (Leśniów, Zygmunt, Halszka, Dobro Woda, Święto Woda, and Zimny Sztok) using integrated geochemical modeling, health risk assessment, and water quality indexing. Seasonal sampling revealed distinct temporal patterns in major ion concentrations. Calcium and magnesium concentrations were significantly higher during winter (Ca 2+ : 90–96 mg/L; Mg 2+ : 5.1–7.2 mg/L) compared to summer (Ca 2+ : 19–45 mg/L; Mg 2+ : 3–5 mg/L), attributed to reduced biological uptake and enhanced carbonate dissolution at lower temperatures. Conversely, sodium (2.5–11 mg/L) and chloride (13–28 mg/L) concentrations peaked during summer due to evaporative concentration and anthropogenic influences. Heavy metals (Fe, Mn, Hg) showed maximum concentrations in summer. Hydrogeochemical analysis identified two water types: Ca–Mg–HCO 2 and Ca–Mg–Cl/SO 4 . PHREEQC modeling revealed undersaturation in calcite (−4.27 to 0.1), dolomite (−9.08 to −1.25), and gypsum (−2.6 to −1.78). Canadian Water Quality Index (CWQI) values (84.57–96.52) classified all samples as “Good,” while Heavy Metal Pollution Index (HPI) values (20.27–120.10) and Metal Index (MI) values (0.58–2.35) indicated highest contamination at Zimny Sztok and Leśniów. Ecological Risk Index (ERI) values (0.18–4.17) suggested low ecological risk. Health risk assessment demonstrated children face 1.5−2× higher non-carcinogenic risks than adults, with maximum hazard index (HI) of 3.37 at Leśniów, primarily from mercury exposure with hazard quotient (HQ) = 3.01. Corrosion indices indicated predominantly corrosive conditions with minimal scaling potential.