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Groundwater in confined aquifers is the preferred water resource worldwide, and its hydrochemical quality is the premise for sustainable development. A systematic hydrogeochemical research was conducted to get insight into the hydrochemical characteristics, genesis, and potential health threats of confined groundwater, based on analytical data of 45 groundwater samples collected from the urban area of Hengshui, Central North China Plain (NCP). The results showed most groundwater had desirable hydrochemical quality with a nearly neutral to slightly alkaline nature and dominantly soft-fresh Cl-Na face. Solute chemistry was governed by rock-water interaction including minerals dissolution and ion exchange, but out of the anthropogenic influences. All nitrogen pollutants and Zn were within the desirable limit, while F−, Mn, and Fe were beyond the desirable limit recommended by WHO in 28.9%, 15.6%, and 68.9% of samples. Overall chronic health risk from these toxic elements was identified in terms of various populations and mainly contributed by F−. Infants were more prone to the health risks of aqueous pollutants. Differential water supplies based on hydrochemical quality are recommended, and water improvement measures are suggested to be conducted aiming at the harmful fluoride in confined groundwater. The present research could provide valuable references for the health sustainability of confined groundwater utilization in sedimentary plains like NCP worldwide.

Groundwater of alluvial fan plains is the foremost water source, especially in arid/semiarid regions. Its contaminants are big issues for water supply and public health concern. To reveal the groundwater chemistry, contaminants sources and health threats in alluvial aquifers, 81 groundwaters were collected from a typical alluvial fan plain of northern China for nitrogen, fluoride and major ions analysis. Statistical analysis and hydrochemical diagrams as well as human health risk assessment were performed. Nitrate is widely distributed and 53% of groundwaters exceed the permissible limit with the maximum concentration up to 326 mg/L. The distributions of nitrite, ammonia and fluoride contaminants are sporadic in spatial, and the concentrations of fluoride in groundwaters are slightly beyond the permissible limit of 1 mg/L. The hydrochemical facies shift from HCO3-Ca or Mixed HCO3-Na·Ca type to Mixed Cl-Mg·Ca and Cl Ca type with the increase of nitrate content. Two factors (Factor-1 and Factor-2) are extracted by factor analysis and account 63% of the total variances. The positive loading of F− and negative loading of NO3− on Factor-2 reveal geogenic and anthropogenic origins, respectively. The significant positive loadings of TDS, TH, SO42−, Cl−, Ca2+, Mg2+ on Factor-1 reveal the governing mechanisms on groundwater chemistry by intermixed sources of geogenic origins and anthropogenic inputs. Hydrogeochemical evolution in the study area is driven by both water-rock interaction and anthropogenic forces. Anthropogenic inputs/influences are the dominated forces increasing groundwater nitrate content and salinity in the piedmont zone and the residential and industrial zone of the southeastern lower parts, and would pose potential non-carcinogenic risks to various populations via oral intake pathway. Rational measures should be taken to protect groundwater quality out of the threats of anthropogenic pollution. The geogenic fluoride in groundwater would threat the health of children through oral pathway and should be also concerned. Capsule The driving forces of groundwater chemistry in alluvial fan plains were revealed using integrated approach of factor analysis and geostatistical modelling.

Groundwater is an essential resource for sustainable development, whose quality is significant for human health. In the present study, twenty-eight groundwater samples were collected from domestic tube wells and public water supply wells in the Suining area, southwestern China. The integration of statistical analysis, correlations of ions, geomodelling, and entropy-weighted water quality index (EWQI) was carried out to clarify the hydrochemistry and groundwater quality in the study area. By the statistical analysis, the cations followed the concentration order as Ca2+> Na+> Mg2+> K+, while anions’ concentrations were HCO3− > SO42− > Cl− > NO3− > F−. Piper trilinear diagram showed the hydrochemical type was characterized as Ca-HCO3. Correlations of ions and geomodelling revealed the concentrations of major ions were mainly determined by carbonate dissolution and ion exchange process, and NO3− concentrations were controlled by agriculture activities. EWQI computation demonstrated that most of the groundwater samples possessed EWQI values higher than 100. Therefore, groundwater quality is lower than the permissible limit of the World Health Organization (WHO), suitable for drinking purposes in the Suining area. Our study provides vital knowledge for groundwater management in the Suining and other similar areas.

The Yanjing region of Tibet is famous for its saline springs and salt deposits. It is located between the Qiangtang and Lanping-Simao basins that also have saline springs and salt-bearing strata. The hydrochemical and stable water and C-13 isotopes of saline springs, hot springs, surface waters and rocks from Yanjing are reported and compared with data from those basins. Results indicate that 1) the saline springs are high TDS, Na-Cl type waters and brines with unusually high K contents that indicate interaction with evaporite minerals; 2) for the saline springs from Yanjing, the circulation depth is moderate, 3–4 km, and the Late-Triassic strata (T3b) are considered as the salt bearing strata and the aquifer; 3) the hot springs are of two distinct geochemical types, Na·Ca-HCO3 type waters with higher temperature, and Na·Ca-SO4 waters with somewhat higher TDS content; and 4) all waters are of meteoric origin or have a large meteoric component. Furthermore, the lithofacies' evolution of the salt-bearing belt from Lanping-Simao to Qiangtang, and the affinities of Yanjing with these two basins, are also discussed, and it is concluded that the saline water in Yanjing has a good utilization prospect with regard to sylvite.

The Nibashan tunnel is a major project mountain tunnel on Ya’an to Lugu lake expressway in Sichuan province. The tunnel relative elevation of about 2,100 m and the maximum depth of 1,701 m, belongs to the deep buried and extra-long tunnel. The tunnel’s strata are mainly igneous rock of Suxiong Formation, Lower Sinian. The rock type belongs to rhyolite (69 %), andesite (21 %) and a small amount of pyroclastic rocks, dykes and terrigenous clastic rocks. Based on the field investigation and drilling data of Nibashan tunnel, analysis of igneous rock reservoir space and performance factor by the lithology, lithofacies, fractures, structure and diagenesis of igneous rock. It considered that the igneous rock reservoir water storability was mainly affected by tectonism, and the reservoir site is located in the tectonic fracture zone. Finally, through the high pressure water pressure test and pumping test of drilling on Nibashan tunnel, obtaining the water reservoir and water inrush characteristic of igneous rock and geological flaws in tunnel, and providing a theoretical basis to construct safely and smoothly the tunnel.