Groundwater contaminations based on the release and transportation of leachate from municipal solid waste (MSW) landfills are a potential hazard to the ecosystem and its inhabitants. In this study, nine chemical compositions of groundwater quality were collected and analysed from 16 monitoring wells and two ponds around the Diaoyushan MSW landfill in the north of Jiangsu Province, China. Multiple analyses were performed to assess the redox conditions and the groundwater environment. It was indicated that the landfill was in a low and stable biodegradability phase, and the most influential phase was the initial stage of the landfill site; the leachate leakage was the principal pollution source (49.18%) for the local groundwater environment. Artificial drainage of Dongdasha village expanded the contaminant plume scopes and deteriorated water quality further. The polluted groundwater area was provided with high concentrations of total hardness, Cl⁻, SO₄²⁻, total dissolved solids (TDS) and Pb.

Coal mining can cause groundwater pollution, and microorganism may reflect/affect its hydrochemical characteristics, yet little is known about the microorganism’s distribution characteristics and its influence on the formation and evolution of mine water quality in underground coal mines. Here, we investigated the hydrochemical characteristics and microbial communities of six typical zones in a typical North China coalfield. The results showed that hydrochemical compositions and microbial communities of the water samples displayed apparent zone-specific patterns. The microbial community diversity of the six zones followed the order of surface waters > coal roadways > water sumps ≈ rock roadways ≈ goafs > groundwater aquifers. The microbial communities corresponded to the redox sensitive indices’ levels. Coal roadways and goafs were the critical zones of groundwater pollution prevention and control. During tunneling in the panel, pyrite was oxidized by sulfur-oxidizing bacteria leading to SO₄²⁻ increase. With the closure of the panel and formation of the goaf, SO₄²⁻ increased rapidly for a short period. However, with the time since goaf closure, sulfate-reducing bacteria (e.g., c_Thermodesulfovibrionia, Desulfobacterium_catecholicum, etc.) proportion increased significantly, leading to SO₄²⁻ concentration’s decrease by 42% over 12 years, indicating the long-term closed goafs had a certain self-purification ability. These findings would benefit mine water pollution prevention and control by district.

Complex hydrogeological conditions in China’s coal mines have contributed to frequent mine water disasters. A simple and effective method to determine water inflow sources and paths is therefore essential. The Longmen Mine, located in Henan Province, in central China was used as a case study. A Piper diagram and cluster analysis were used to screen the characteristic values of 18 water samples from potential aquifers. A comprehensive fuzzy evaluation of the groundwater ions was carried out to determine the main source of the total mine inflow. Then, based on conservation of ionic masses, a matrix function was established to calculate the groundwater recharge composition. Finally, using measured water inflows for the Cambrian limestone aquifer, the calculated and observed results were compared. The results showed that the Carboniferous Taiyuan Formation limestone aquifer (the L₇ limestone aquifer) accounts for 60.8% of the total mine inflow, while the Cambrian limestone and roof sandstone aquifers account for 34.8 and 4.4% of the inflow, respectively. The normal mine inflow totals about 19,200 m³/day, of which 6,840 m³/day is from the Cambrian limestone aquifer. This agrees well with the calculated value of 6,720 m³/day. Thus, the method is feasible and reliable.

This study analyzes the ability of coal mine underground reservoirs to protect groundwater resources. As the demand for coal mining continues to increase, the potential impact on groundwater resources around mines has become a growing problem. Underground water reservoirs, also known as coal mine underground reservoirs, have been constructed as a solution to protect water wastage in mining operations. However, there is a lack of awareness related to the ability of underground water reservoirs in mines to protect groundwater resources. In this study, we used FLAC^3D software to analyze the formation process, water storage volume, and central storage location of the underground water reservoir in Zhangshuanglou Coal Mine. The results show that the damaged volume is 3.39 × 10⁶ m³, and the groundwater resources that can be protected by coal mine underground reservoirs in the study area amount to 1.98 × 10⁵ m³. We found that the storage capacity of underground reservoirs is more significantly affected by the extent of mining, which can be expressed as y = 49,056.44 + 255.75x + 1.46x² (R² = 0.995) (x ≠ 0). Additionally, the water storage location obtained through simulation can provide a reference for the construction of underground reservoir regulation and water storage projects. The results of the water quality analysis indicate that the concentrations of SO₄²⁻ decreased by 42% with the closure of the mining area, and the pH also gradually converged to neutral. This highlights the significant role of underground water reservoirs in coal mines in promoting green production and protecting water resources and the environment.