Due to the fact that strontium (Sr) is not involved in the scope of supervision of drinking water in China, the Sr concentration in public drinking water and its related health risks have been neglected for a long time. In this research, public drinking water samples were collected from 314 cities across the country to reveal the concentration and spatial distribution of Sr in public drinking water. In addition, the Monte Carlo method (a statistical simulation method) was applied to evaluate the Sr intake from drinking water and human health risks among different age groups and different regions. As shown in the results, the Sr was in the concentration range of 0.005–3.11 mg/L with a mean value of 0.360 mg/L. There were significant differences in the Sr concentration in different regions; in general, it was high in the north and low in the south. The Sr intakes of infants, children, teens, and adults from drinking water were 0.273, 0.503, 0.633, and 0.784 mg/day, respectively. There was a significant positive correlation between Sr concentration in drinking water and bone mineral density (BMD) in the elderly. Especially, the correlation coefficients (r) between Sr concentration and the BMD of the elderly whose age fell in the range of 60–70 years were 0.692 (male) and 0.483 (female). In addition, the Sr concentration in drinking water was positively correlated with the incidence of children’s rickets (r = 0.411), while the Ca/Br ratio was negatively correlated with the incidence of children’s rickets (r = − 0.410). According to the health risk assessment, among people of different ages, infants’ hazard index (HI) value was the highest. The mean value and 95th percentile value were 0.066 and 0.247. Non-carcinogenic risk of Sr through drinking water among different people in different regions was less than 1, which meant no significant damage to human health. This study is the first time to systematically investigate Sr in public drinking water across the whole country. More importantly, the conclusions can be applied to risk control and management of public drinking water.

Tetracycline is one of the most commonly used antibiotics in the world. Eventually, large amounts of this contaminant will enter into the subsurface environment, where a variety of ions exist. In this study, the effects of divalent metal cations (Mg²⁺, Ca²⁺, Pb²⁺ and Cu²⁺) and inorganic anions (Cl⁻, NO₃ ⁻, SO₄ ²⁻ and H₂PO₄ ⁻) on the transport of tetracycline in saturated porous media were investigated. Both batch and column experiments were conducted to determine the interactions between tetracycline and sand. Batch sorption experimental results showed that the presence of divalent metal cations could increase the sorption of tetracycline onto sand due to the cation-bridging mechanism. When Na⁺ was the counterion in the background solution, anions caused a significant decrease in tetracycline sorption owing to the occupation of some adsorption sites by anions and the decrease of electrostatic attraction. Column experiments indicated that the inhibition effects of divalent cations followed the order of Cu²⁺ > Pb²⁺ > Ca²⁺ ≈ Mg²⁺; the regular pattern might be related to their different complexing strengths. The presence of inorganic anions enhanced the mobility of tetracycline following the order of H₂PO₄ ⁻ > SO₄ ²⁻ > NO₃ ⁻ > Cl⁻. Transport-enhancement effects of anions were ascribed to competition between inorganic anions and tetracycline for deposition sites on sand surfaces. However, when Ca²⁺ was the counterion, the differences in the breakthrough curve of tetracycline among three inorganic anions (i.e., SO₄ ²⁻, NO₃ ⁻ and Cl⁻) were very small. In this case, the transport-inhibiting effects of anions could be counterbalanced by the transport-enhancement effects of the cation-bridging effect. Also, the two-site nonequilibrium transport model was applied to analyze the transport data. Findings from this study improve our understanding of the transport of tetracycline in saturated aquifer materials.

Rugao city is a typical longevity area taking shallow groundwater as the primary drinking water source. To determine the relationship between longevity and groundwater conditions, the hydrogeochemical characteristics and related causes of potable groundwater were investigated. On this basis, the water quality index (WQI) and hazard index (HI) of groundwater were evaluated. Meanwhile, the nutrient indicators beneficial to human health, like Ca and Mg concentrations, were also considered to explore the relationship. The results were as following: (1) 91.3% of water samples fell under the Ca/Mg-HCO₃ water type, which resulted from the dissolution of silicate rock. Na, Cl^-, Br, B in groundwater emanated from seawater intrusion. The abnormal concentrations of NO₃^- and As also indicated that anthropogenic activities had exerted significant influences on groundwater quality. (2) The average WQI value was 30.19, which meant that the overall groundwater quality in Rugao city was pretty good. However, 8 water samples were found to have HI values above 1, which might be attributed to the high concentration of As (maximum value 0.0407 mg/L; mean value 0.0076 mg/L). In general, low WQI and HI values corresponded to towns with a high longevity population; what's more, WQI and HI values of Rugao city were lower than those of non-longevity areas. (3) Comparing with adjacent non-longevity areas, the potable groundwater in Rugao city had the characteristics of high Ca (mean value 123.57 mg/L), high Mg (mean value 50.33 mg/L) and high SO₄^2- (mean value 525.19 mg/L). The daily intake of Ca and Mg from drinking water could meet 12.4% and 22.4% of daily Ca and Mg requirements, respectively. Also, the areas where the Sr and B concentrations were higher usually had higher life expectancy. The high concentrations of Ca, Mg, SO₄^2-, Sr and B in drinking water, as well as low WQI and HI values, probably contribute to physical health and longevity. This research helps provide an insight into the relationship between groundwater quality and health and can serve as a reference for drinking water quality management.