Environmental and Health Risks Posed by Heavy Metal Contamination of Groundwater in the Sunan Coal Mine, China

Multiple stable isotopes and geochemical approaches to elucidate groundwater reactive transport paths in mining cities: A case from the northern Anhui, China

Mining cities are ecotone areas where human and natural components interact. Indeed, the negative effects of mining activities on drinking water quality have become a serious public concern worldwide. To elucidate groundwater genesis and reactive transport path controlling the water pollution, a multi-bodies system in the Sunan Mine area in China was considered in this study. The results of the mineral phase characterizations, hydrochemical analysis, and multiple stable isotopes (δ2H/δ18O, δ34S and 87Sr/86Sr) indicated that calcite, dolomite, gypsum, quartz, halite, organic carbon, and gases (O2, CO2 and H2O) were the primary reactants in the aquifer system, accompanied by dissolution and precipitation of minerals, cation exchange, desulfation, and evaporation. An inverse hydrogeochemical model was employed to identify three paths, Path 1 demonstrated that mine water mainly originated from the Quaternary loose aquifer water (QLA), Permian fractured sandstone aquifer water (PFA), and Carbonifer fractured limestone aquifer water (CFA), accompanied by high K++Na+ and HCO3- concentrations due to the carbonate dissolution, halite dissolution, and cation exchange processes. Path 2 showed that the recharge of the CFA and Ordovician fractured limestone aquifer (OFA) occurred from the shallow recharge zone to the deeper OFA water through faults and fractures, mainly involving halite dissolution, carbonate dissolution, and gypsum dissolution. Path 3 demonstrated the interaction between the Hui River, collapsed pond water, and QLA, accompanied by gypsum dissolution, calcite dissolution, and cation exchange. Although the shallow QLA quality met the WHO drinking water standards, the pollution risk from the surface collapse pit water cannot be ignored. Therefore, effective approaches need to be considered in the study area to reduce the connection between the collapse pit water and QLA. The study results can help decision makers to predict water quality of complex water systems in ecotone areas and other similar regions worldwide.

Geochemical modeling and hydrochemical analysis for water quality determination around mine drainage areas

Water sources in mining areas do not retain their natural quality due to the influence of mine drainage. Water quality test was through hydrochemical analysis, speciation modeling, and saturation indices. Water samples were analyzed for pH, conductivity, nitrate, phosphate, sulfate, chlorite, sodium, magnesium, calcium, turbidity, total hardness, lead, zinc, iron, copper, cadmium, manganese, nickel, and chromium. Mean values of turbidity (0.13 mg/L), lead (0.01 mg/L), and cadmium (6.40 mg/L) exceeded their permissible values for potable water. Multivariate statistical analysis shows geogenic and anthropogenic sources of chemical species. Chemical speciation shows that the cations exist mostly in their soluble and mobile forms as free ions. Water quality index of 35-45.5 shows good water for drinking, irrigation, and industrial uses. The values of 63.8-68.8 and 103-121 reflect suitable water for industrial and irrigation uses. The research is integrated and credible in predicting groundwater pollutants to solve water pollution problems. PRACTITIONER POINTS: The mean value of turbidity, Pb, and Cd exceeded the WHO/NSDWQ standards for potable water. Correlation and principal component analyses show that the chemical species are from both geogenic and anthropogenic sources. Chemical speciation shows that the cations exist in their soluble and mobile forms as free ions except Cr. Saturation indices show that the minerals anhydrite, anglesite, vivianite, langite, larnakite, melanterite, and mirabilite are undersaturated in the water sources. Water quality index shows that the water is more suitable for irrigation than drinking and industrial uses.

Sources, distribution, associated health risks and remedial technologies for inorganic contamination in groundwater: A review in specific context of the state of Haryana, India

Haryana is one of the leading states in India in the agricultural and industrial production. With the expansion of these sectors, a continuous increase in water demand is leading to water crises arising from overexploitation and quality deterioration of the available water. Contamination of aquifer resources is a significant concern, because majority of population depends on the groundwater for various agricultural, industrial, and domestic needs. This review article provides an overview of groundwater contamination, associated health risks with different contaminants with regions severely affected by poor water quality, and delves in identifying the sources, by observing and recognising the types of industries dominant in the state with types of effluents discharge. It further suggests the possible mitigation measures such as advanced remedial technologies and proper management practices from the consequent contamination sources. It has been observed during the perusal of various studies and data that the degree of contamination was considerably higher in districts with heavy agro-industrial activities. The groundwater resources in three highly industrialized districts were found to be gravely contaminated with toxic heavy metals. Alongwith heavy metals, the salinity, hardness, nitrate, and fluoride are also posing significant problems in the aquifer resources of Haryana state. The article also discusses various technologies for remediation of different pollutants from groundwater so it can be made potable after treatment.

Ecological Risk Assessment and Source Identification of Heavy Metals in Soils from Shiyang River Watershed in Northwest China

Shiyang River Watershed is an important ecological barrier and agricultural production area in Northwest China, and the study of soil heavy metal content, distribution, and sources is important for agricultural product safety, pollution control, and ecosystem health. In this paper, 140 soil samples were collected from 28 stations to assess the level of heavy metal (Arsenic (As), Copper (Cu), Lead (Pb), Cadmium (Cd), Chromium (Cr), Mercury (Hg), Nickel (Ni), Zinc (Zn)) contamination, pollutant sources and influencing factors of soil in Shiyang River Watershed through determination of the metal contents and statistical analysis. The results indicated that the soils in the study area are typical saline soils in arid zones. The enrichment factors (EF) of As, Cr, Cu, Ni, Zn, and Pb indicate no contamination, and the EFs of Cd and Hg suggested minor contamination. Although the concentrations of Cd and Hg in soil are lower than others, they are more biotoxic and exhibit a moderate-high ecological risk. The index of geoaccumulation (Igeo) values reflect that most of the stations, especially the three groups of samples from depths of 10-20 cm, 20-40 cm, and 40-80 cm, are below the contamination threshold for all heavy metals. The chemical speciation of heavy metals, principal component analysis, and correlation analysis showed that Cr, Cu, Pb, Cd, Ni, and Zn mainly come from the natural accumulation upon weathering of soil-forming matrices. Hg and As mainly come from anthropogenic contributions. The effect of agricultural crop cultivation on soil heavy metal contamination is mainly through farm irrigation and crop-soil interactions, which accelerate the release of heavy metals through the weathering of soil-forming parent material and irrigation, which transports the heavy metals below the surface. The results of this study can provide a scientific basis for the involved authorities to formulate reasonable policies on environmental protection and pollution control.

Source apportionment and ecological health risks assessment from major ions, metalloids and trace elements in multi-aquifer groundwater near the Sunan mine area, Eastern China

Evaluating the ecological health risks created by major ions, metalloids and trace elements concentrations in groundwater and pollution sources were essential to effectively protect groundwater resources. For this study, A total of 93 samples were collected from multiple aquifers in the Sunan mining area, eastern China. The Positive matrix factorization (PMF) model results revealed the following sources, in percentages. The Quaternary loose aquifer (QLA) water includes CaMg mineral dissolution (30.3 %), salinity (28.2 %), metal industrial wastewater (26.3 %), iron and manganese minerals (8.0 %) and coal gangue (7.2 %). The Permian fractured sandstone aquifer (PFA) water includes CaMg mineral dissolution sources (29.8 %), mine wastewater (28.6 %), aluminosilicate (21.6 %) and pyrite source (20.0 %). The Carbonifer fractured limestone aquifer (CFA) water includes and mine wastewater (34.2 %), CaMg mineral dissolution (25.4 %), pyrite (22.6 %) and aluminosilicate (17.7 %). The Ordovician fractured limestone aquifer (OFA) water includes manganese and aluminum metal minerals (27.9 %), halite dissolution materials (24.9 %), industrial and agricultural waste water (24.0 %) and calcium‑magnesium minerals (23.2 %). A PMF-based assessment of ecological health risk indicates that the concentrations of elements As and Co are the dominant elements impacting non-carcinogenic and carcinogenic risks; and As, Cr, and Cu are the dominant elements impacting potential ecological risks. These mainly originate from geological sources, coal gangue sources, mine drainage sources and agricultural sewage discharge sources. The study showed the sources of groundwater pollution in multiple aquifers and their priority treatment areas, providing a basis for groundwater management and protection.