In order to achieve the rational development and utilization of underground water resources in the Dongsheng mining area under coal mining conditions, we selected the upstream area of Beiniuchuan River as a typical region. Through field investigations, sampling tests, and the application of hydrochemical and isotope techniques, we traced the groundwater circulation mechanism in the Dongsheng mining area. The results indicate that the majority of the Quaternary alluvial and Salawusu Formation groundwater is of the HCO₃-Ca type, with a TDS content below 300 mg/L. However, in some areas, the hydrochemical type becomes complex due to anthropogenic contamination. The shallow-buried Yan’an Formation groundwater is either of the HCO₃-Ca·Mg type or the HCO₃·SO₄-Ca·Mg type, with TDS content ranging from 200 to 750 mg/L. The Yan’an Formation at depths greater than 40 m exhibits complex water chemistry, with a TDS content higher than 500 mg/L, and it belongs to the Cl-Na type, with TDS around 700 mg/L. The hydrogen and oxygen isotope results indicate that the local groundwater is primarily recharged via atmospheric precipitation. The ³H and ¹⁴C results show that the Quaternary alluvial and shallow-buried Yan’an Formation groundwater has a fast turnover rate, while the deep-buried Yan’an Formation and Yan’chang Formation groundwater have a slower turnover rate. The regional groundwater circulation can be generalized into three flow systems: shallow, intermediate, and deep. Under the influence of coal mining activities, the water circulation conditions in the study area have undergone significant changes. The sealing integrity of the Yan’an Formation has been compromised, and precipitation and shallow groundwater have enhanced the vertical infiltration capacity of the formation, increasing the proportion of groundwater participating in the intermediate flow system. As a result, the river runoff mainly dependent on the discharge from the shallow flow system has drastically decreased.

The origin and geochemical evolution of formation water trapped in continental shale of the Dameigou Formation in the Northern Qaidam Basin have been investigated for selecting unique signatures of formation water compared with shallow groundwater and conventional oilfield brines (COB). The formation water, which is trapped in a closed shale with no halite and sylvite in it, has a higher Cl/ Br ratio (1183.43) than that of seawater (657.89). Furthermore, delta H-2 (-67%) and delta O-18 (-8.1%) values of the formation water lies near the local evaporation line. These suggest that the formation water originated from evaporated rainwater. The temperature (>120 degrees C) of the Dameigou Formation and the vitrinite reflectance values (1.0-1.3%) of the shale indicate that thermochemical sulfate reduction (TSR) was responsible for the depletion of SO4 in the formation water. The increased CO2 concentration and Mg/Ca ratio in formation water leading by TSR caused kaolinization of plagioclase feldspar and dolomitization, respectively. The formation water depletion in Ca and HCO3 was caused mainly by calcitization. The Na/Ba ion exchange and dissolution of continental borate occurring in the shale-formation water system were vital to the geochemistry of trace elements in formation water. All these geochemical processes have given the formation water distinctive delta S-34-H2S (25.9%), Sr-87/Sr-86 ratio (0.713842), Ba/Ca ratio (2.60x10(-2)) and delta B-11 (1.1%) signatures compared with COB in shallow groundwater.

In the karst regions of Southwest China, groundwater commonly discharges to the surface as springs, which serve as a primary drinking water source for local residents. Accordingly, assessing spring water quality and associated human health risks in karst watersheds is critical to sustainable regional economic development. This study investigated the water source area of the Daotian River in Bijie, Guizhou Province, based on 48 collected spring water samples (comprising 30 from dolomite springs, seven from limestone springs, and 11 from non-karst springs). Hydrochemical parameters derived from field surveys and laboratory analyses were used to identify groundwater hydrochemical facies and determine their underlying controlling factors. Water quality and non-carcinogenic human health risks via oral ingestion were assessed using the integrated-weight water quality index (IWQI) and a human health risk assessment (HHRA) model. The results indicate that the dolomite springs are predominantly of the HCO₃–Ca·Mg and HCO₃·SO₄–Ca·Mg types, the limestone springs exclusively exhibit a hydrochemical type of HCO₃–Ca, while the non-karst springs are primarily of the HCO₃–Ca and HCO₃·SO₄–Ca·Mg types. Rock weathering and agricultural activities serve as the dominant factors governing the groundwater geochemistry across the river basin. The water quality assessment indicates that the spring water samples exhibited IWQI values ranging from 16.02 to 100.91, with those of excellent, good, medium, and poor water quality accounting for 14.58%, 60.42%, 20.83%, and 4.17% of the total samples, respectively. The water quality assessment reveals that the hazard index (HI) values of the spring water samples varied from 0.06 to 3.08. Among the assessed hydrochemical constituents, NO₃⁻ and Cr contributed the most significantly to the HI, accounting for 70.39% and 13.99% of the total risk, respectively. Monte Carlo simulations further indicate that the ingestion rate (IR) and average exposure time (AT) exerted a substantial influence on the resulting HI values. The spatial patterns of the HI for the four target demographic groups (infants, children, adult females, and adult males) align with the spatial distribution of the IWQI values of the river basin, with high-value zones of both metrics concentrated in the lower reaches near the river basin outlet. From the perspective of oral ingestion, springs in the middle and lower reaches of the river basin impose significantly higher potential non-carcinogenic health risks to infants compared to other demographic groups, while the vast majority of springs pose low health risks to adults and children. The results of this study provide a scientific framework to support policymakers in formulating sustainable strategies for water resource management in small karst watersheds.

Climate change and human activities have intensified the imbalance between water supply and demand in the Shule River Basin. Prominent issues such as groundwater over-exploitation and insufficient ecological base flow have significantly constrained the high-quality development of the region. An evaluation system was developed comprising 20 indicators across four subsystems: water resources, society, economy, and ecosystems. The entropy weighting method was employed to determine the weights of each indicator. The coupling coordination degree of the water resource–society–economy–ecosystem system from 2003 to 2022 was assessed using a coupling coordination degree model. Network analysis was applied to evaluate the correlation and connectivity among indicators. A barrier diagnostic model based on indicator deviation was further constructed to identify key constraints within the system. The results showed that the overall coordination degree of the coupled system increased from 0.217 in 2003 to 0.409 in 2022, shifting from a moderately uncoordinated state to a weakly coordinated one. However, the coordination level remained low due to fluctuations in the water resource subsystem. The ecological and economic subsystems functioned as critical coupling hubs, while strong negative interactions within the water resource subsystem emerged as major constraints to coordinated development. Long-term dominant barriers included the proportion of water used for ecological and agricultural purposes, as well as per capita food production. After 2019, water resource-related indicators, such as per capita water availability and water production modulus, showed a marked increase in obstruction levels, highlighting the persistent challenges posed by water scarcity and inefficient utilization.