Groundwater In China Research Articles

Groundwater nitrate contamination in China: Spatial distribution, temporal trend, and driver analysis

China's groundwater is facing a significant threat from nitrate pollution. Here we analyzed 2348 regional surveys of groundwater nitrate levels in China from 1990 to 2020, examining distribution, trends, and drivers. This study uncovers a concerning rise in nitrate pollution, with estimated median nitrate levels climbing from 3.84 mg/L in 1990 to 6.94 mg/L in 2020. A stark contrast is observed between regions: the northern areas have a median nitrate concentration of 8.54 mg/L, significantly higher than the southern regions, where the median is just 7.15 mg/L. From 1990 to 2020, agricultural activity consistently emerges as the dominant driver of changes in groundwater nitrate concentrations, while groundwater exploitation, domestic pollution, and industrial production also contribute to varying degrees. This analysis highlights the urgency for region-specific policies and interventions to address the escalating nitrate pollution in China's groundwater.

China's groundwater situation in 2011–2020: Dynamic evolution, Influencing Factors, and sustainable development

Groundwater plays important roles in resource security and ecological maintenance and is sensitive to changes in the natural environment and human activities. It is of paramount importance to investigate the dynamic evolution trend of groundwater and its affecting factors and sustainable development. This paper takes mainland China as the study area, using data sourced from the Groundwater Dynamic Monthly Report, the China Water Resources Bulletin, and the Provincial Water Resources Bulletin. The temporal and space-time evolution trend of groundwater depth in 2011–2020 is determined, along with the correlation between variations in groundwater resources and precipitation, the factors affecting these changes, and the sustainability of groundwater use. The results are as follows: (1) The northern and western regions of mainland China had a greater depth of groundwater compared to the southern and eastern regions. The largest groundwater depth is in the Northwest Rivers Basin (Nw RB), which can reach 17.61–21.10 m, and the shallowest groundwater depth is in the Southeast Rivers Basin (Se RB), only 1.61–5.19 m. (2) Regarding the factors affecting the changes in groundwater resources, precipitation, land use pattern, human activities, and industrial and agricultural water use are highlighted. (3) Overall, the percentage of groundwater in the total water supply has declined. The optimization of groundwater resource allocation and the adjustment of industrial structure have resulted in the coordinated utilization of groundwater resources. The research establishes a scientific foundation for ensuring national water security and promoting sustainable economic and social development.

Critical depths of the vertical transition zone between modern infiltration water and fossil groundwater in China

Older groundwater is generally more susceptible to overdraft and also more difficult to recover once contaminated. To understand the prevalence and vulnerability of fossil groundwater infiltrated before Holocene, a global assessment has been conducted recently, but the analysis results for China have been limited by the collection of data. In this study, we combined the groundwater isotope data from the literature databases of CNKI (China national knowledge infrastructure) and SCIE (Science citation expanded) and established the groundwater age dataset of China by virtue of the water samples from 1441 wells. By reconstructing the historical precipitation 3H records of China and using the late-Quaternary atmospheric 14C, the fractions of the modern groundwater that infiltrated after the year 1953 and the fossil groundwater that infiltrated before 12,000 years in the groundwater samples have been calculated based on the straight-forward mixing models. Then we evaluated the extent and depths of the modern and fossil groundwater in the major 16 groundwater-supply areas of China. The results show that the exploitation of deep groundwater mainly occurs in northern China, such as in the Ordos Basin, the North China Plain, and the Hexi corridor, etc. The average critical depth of the vertical transition zone between modern infiltration water and fossil groundwater in China is about 300 m, beneath which more than half of the water samples are dominated by fossil groundwater. Meanwhile, at depth greater than 420 m, the groundwater can rarely be recharged by the modern precipitation. Besides, in China, modern and fossil groundwater, respectively, share 15–45 % and 20–85 % of the total groundwater storage in the uppermost 1000 m of the crust.

Prioritization of organic contaminants in China's groundwater based on national-scale monitoring data and their persistence, bioaccumulation, and toxicity

There has been increasing concern regarding the adverse environmental and health effects of organic pollutants. A list of priority control organic pollutants (PCOPs) can provide regulatory frameworks for the use and monitoring of organic compounds in the environment. In this study, 20,010 groundwater samples were collected from 15 “first level” groundwater resource zones in China. Fifty (50) organic compounds were analyzed based on their prevalence, occurrence, and physicochemical properties (persistence, bioaccumulation, and toxicity). Results showed that 16 PCOPs, including 12 pesticides, 3 aromatic hydrocarbons (AHs), and 1 phthalate ester, were recognized. Pesticides and AHs accounted for 75 % and 18.75 % of the high-priority pollutants, respectively. There were significant differences in PCOPs between confined and phreatic groundwater. Higher concentrations of pesticides were mainly detected in phreatic groundwater. PCOPs detected in samples from the 15 groundwater resource zones were mainly pesticides and AHs. The groundwater data indicate that the organic compounds detected in the Yellow River Basin (YRB), Yangtze River Basin (YZB), Liaohe River Basin (LRB), and Songhua River Basin (SRB) are mainly categorized as Q1 (high priority) and Q2 (medium priority) pollutants based on the contaminants ranking system in China. The findings from this study offer a snapshot of the wide distribution of PCOPs in the surveyed regions, and are expected to establishing treatment and prevention measures at both the regional and national levels in China.

Influence of Mineral Deposition on the Retention of Potentially Hazardous Elements in Geothermal Spring Sediments

Geothermal springs are known to contain a variety of potentially hazardous elements (PHEs), which may threaten human health. Their release on Earth’s surface is largely dependent on the retention by the sediments at the spring outflux. In this study, the hot spring waters and the sediments at the corresponding sites were collected from the Nagqu geothermal field on the Tibetan Plateau. The water geochemistry and sediment mineralogy were analyzed using inductively coupled plasma mass spectrometry (ICP-MS), X-ray fluorescence (XRF), and X-ray diffraction (XRD). The association of PHEs with minerals was analyzed. The results indicate that while the concentrations of PHEs were highly elevated, Be, As, and Tl in some hot springs exceeded the criteria for class III groundwater in China by up to 2, 2, and 19 times, respectively. Cs occurred at relatively high levels, up to 776 μg/L. As, Co, Se, Tl, and U in the hot spring waters were probably captured by iron sulfide minerals in the sediments, while Be and Cs were strongly retained by the carbonate minerals. The releases of V and Cr were apparently regulated by the clay minerals. Overall, the mobility of PHEs from the geothermal springs is controlled by the deposition of minerals at the spring vents.

Review on Biogeochemical Characteristics of Typical Antibiotics in Groundwater in China

The problem of antibiotic contamination in the environment has attracted much attention in recent years. However, studies on antibiotic contamination in groundwater have only emerged in the last 15 years. In this study, we systematically reviewed the detection methods, distribution characteristics, risk, fate, and sources of antibiotics in groundwater in China, listed the concentrations of the main antibiotic types, and obtained the maximum concentrations by comparing the literature published in the last 10 years. The results show that 65 antibiotics were detected in groundwater in China, with sulfonamides and quinolones receiving the most attention. Antibiotic concentrations are influenced by hydrogeological conditions and seasonal variations, and the ecological risk in most areas is low to medium risk, which is relatively manageable. The highest concentrations found in most of the literatures were in the range of 10–1000 ng/L, but the maximum concentration can reach 47,444.5 ng/L, which requires extra attention. In addition, this study makes recommendations for improving groundwater monitoring surveys and protection measures to prevent the antibiotic contamination of groundwater more effectively.

Occurrence, risk assessment, and in vitro and in vivo toxicity of antibiotics in surface water in China

Antibiotics have been widely detected in the water environment and thus pose a potential threat to human health. Although antibiotics have health-promoting properties, whether and how they affect health at environmental concentrations remains uncharacterised. We detected antibiotics in surface water and groundwater in China. Sulfonamides (851 ng/L) and tetracyclines (1322 ng/L) showed the highest concentrations in surface water, while the highest concentration of sulfonamides detected in groundwater was 250 ng/L. We analysed the distribution of four classes of antibiotics (sulfonamides, tetracyclines, macrolides, and quinolones) and evaluated the associated health risks in the surface water of seven cities. We found that antibiotic pollution caused health risks to the 0–3-months age group, but not to other age groups. We further demonstrated that simulated long-term exposure to environmental concentrations of antibiotics had concentration-dependent toxic effects on L-02 hepatocytes, affected cell proliferation, and induced oxidative damage and DNA damage. Chronic exposure to mixed sulfonamides affected growth, caused liver damage, and reduced the abundance of intestinal flora in mice. Under exposure to antibiotics, the abundance of Helicobacter pylori in the gut flora significantly increased and posed a health risk to humans. These results indicated that exposure to antibiotics at environmental concentrations can cause oxidative damage and inflammation both in vitro and in vivo. These findings add to the body of basic data on the distribution of antibiotics in the water environment, and provide a scientific basis for the evaluation of antibiotic toxicity.

In situ degradation of fluoroquinolone antibiotics in groundwater by CoFe2O4 nanoparticle-activated peroxymonosulfate: Performance, activation mechanism, degradation pathway

For fluoroquinolone antibiotics, which are widely present in groundwater in China and extremely hazardous, highly dispersed CoFe2O4 nanoparticles (NPs) that can efficiently activate peroxymonosulfate (PMS) and rapidly degrade three fluoroquinolone antibiotics, were successfully prepared by the sol-gel method. The presence of Cl− and HCO3− reduced the degradation efficiency of CoFe2O4/PMS system for NOF, while H2PO4− showed a positive effect. The pH range for efficient degradation of fluoroquinolone antibiotics in the CoFe2O4/PMS oxidation system was between 3 and 9. Two reactive radicals, SO4−• and HO•, played an important role in the degradation process. The ability of the catalyst to degrade the antibiotics decreased from the initial 97.12%–88.72% after five repeated uses. The application of density-functional theory (DFT) indicated the chemical bonds in NOF that are vulnerable to free radicals (N13, C5, F19, and O20). Three degradation pathways of NOF were summarized in combination with the LC-MS results. The potential of the CoFe2O4 NPs for practical applications in in situ remediation was verified by testing the migration ability and in situ degradation of NOF in two column experiments. Overall, this paper provides a theoretical basis for the practical application of nanomaterial-activated PMS in ISCO for groundwater remediation.

Fluorine in shallow groundwater in China: A review of distribution, occurrence and environmental effects

With rapid economic development and the increasing demand for drinking water, a large amount of groundwater is exploited, resulting in a high F− content in groundwater, which is harmful to the environment and human body. In this study, 5,464 data points of fluoride in shallow groundwater were collected, and the F− content distribution, occurrence form and environmental impact of shallow groundwater were discussed. The results showed that 1) the F− content in shallow groundwater in China ranged from 0 to 60 mg/L, with a mean content of 0.90 mg/L; the lowest average F− content in shallow groundwater in Southwest China was 0.36 mg/L; South China (1.20 mg/L), Northeast China (1.25 mg/L) and Northwest China (1.25 mg/L) were considered high-fluoride areas, and North China (0.93 mg/L), East China (0.67 mg/L) and Central China (0.80 mg/L) were considered low-fluoride areas. The mean F− content in groundwater differed between provinces and cities. 2) The F− in shallow groundwater mainly occurred in ionic, complex ionic and organic fluoride molecular states. 3) The influence of a high F− content in shallow groundwater on the environment was mainly manifested in the increase in water F− concentration and soil F− and vegetable F− content. The influence of a high F− content on the human body was mainly manifested in an increase in urinary F− content in children, a high prevalence of dental fluorosis in children, an increase in skeletal fluorosis rate in adults with age, and an influence on cognitive function of older adults. These results provide a basis for F− pollution control and high-fluoride water treatment.

Per- and polyfluoroalkyl Substances (PFAS) In China’s Groundwater Resources: Concentration, Composition, and Human Health Risk

As an important class of emerging contaminants, per-and polyfluoroalkyl substances (PFAS) in water resources has been extensively studied. In this study, PFAS contamination in Chinese groundwater was systematically analyzed according to the reported literature. The research on PFAS in groundwater was concentrated in the eastern regions of China and that the concentrations of PFAS in groundwater ranged from N.D. to 26700 ng/L. The detected PFAS were PFBS, PFOA, PFBA, PFHxA, PFHxS, PFHpA, PFOS, PFPeA, PFUnA, PFTeDA, and PFNA. Among them, PFOA, PFBA, and PFBS showed higher concentrations. The concentration and composition of PFAS in groundwater varied significantly across different regions, often attributable to local industrial activities and urbanization. PFOA was the most commonly detected PFAS in the samples and also the primary contaminant in 14 sites. Additionally, PFPeA, PFBA, PFOS, and PFHxA also occupied a significant proportion of the total concentration level. The human health risk of various PFAS was assessed by the value of the predicted no effect concentration (PNEChum). The PNEChum value for PFOS, PFOA, and PFNA is relatively low, indicating a high risk to human health. Combined with the actual detection concentration, PFOS and PFOA are the two highest risk pollutants, which need attention and control. For the last decade, the concentration of PFOS has decreased, but the situation of PFOA was not encouraging. This study reviewed the PFAS contamination in groundwater in China, identified the high-risk substances, confirmed the need for regulation and control, and highlighted the importance of protecting public health during economic development.

Drivers of Groundwater Change in China and Future Projections

Observations worldwide have shown that in recent decades, groundwater depletion intensified notably in many regions. Understanding the interacting drivers of groundwater change enables better human adaptations to climate change and socioeconomic development. Here we use a structural equation model to quantify the contribution of natural and human-induced processes on the groundwater of China by using terrestrial water storage observed by GRACE in combination with climate and socioecological related data at a provincial scale. The results reveal that the influence of climate on groundwater change through indirect impact on the agriculture water consumption is larger than that through direct replenishment. Socioeconomic development contributes in the same order of magnitude as the direct replenishment by climate variabilities to groundwater. In general, forest plays an important role in reserving groundwater at a provincial scale. Based on future climate projections and Shared Socioeconomic Pathways, it is projected that most regions in China will experience a greater groundwater depletion in the future and the variance among regions will become larger.

The Current Status and Prevention of Antibiotic Pollution in Groundwater in China.

The problem of environmental pollution caused by the abuse of antibiotics has received increasing attention. However, only in recent years have antibiotic pollution and its risk assessment to the environment been deeply studied. Although there has been a large number of reports about the input, occurrence, destination, and influence of antibiotics in the past 10 years, systemic knowledge of antibiotics in the groundwater environment is still lacking. This review systematically expounds the sources, migration and transformation, pollution status, and potential risks to the ecological environment of antibiotics in groundwater systems, by integrating 10 years of existing research results. The results showed that 47 kinds of antibiotics in four categories, mainly sulfonamides and fluoroquinolones, have been detected; antibiotics in groundwater species will induce the production of resistance genes and cause ecological harm. In view of the entire process of antibiotics entering groundwater, the current antibiotic control methods at various levels are listed, including the control of the discharge of antibiotics at source, the removal of antibiotics in water treatment plants, and the treatment of existing antibiotic contamination in groundwater. Additionally, the future research direction of antibiotics in groundwater is pointed out, and suggestions and prospects for antibiotic control are put forward.

High abundance of microplastics in groundwater in Jiaodong Peninsula, China

The occurrence of microplastics (MPs, <5 mm) in drinking water has aroused extensive concerns, whereas our understanding of their presence in groundwater, a major source of drinking water, is still limited. The present study investigated the occurrence of microplastics in groundwater sampled from five sites in Jiaodong Peninsula, China. The abundance, type, and size of MPs in the groundwater samples were determined by Laser Direct Infrared following a well-established and quality-controlled analytical route. Notably, MPs were detected in groundwater across all five sampling sites, with high abundances ranging from 87 to 6832 particles/L and an average abundance of 2103 particles/L. The variation of the abundance of MPs was correlated to the distances between sampling sites and anthropogenic activities, which suggested significant impacts of aboveground industry and agriculture on the abundance of MPs in groundwater. Polyethylene terephthalate (PET) and polyurethane (PU) were the dominant polymer types detected in all groundwater samples. The MPs with a size smaller than 100 μm were found to account for >90% of the total MPs detected in four sampling sites, which was likely associated with their migratory routes through surface water runoff and infiltration into the groundwater settings. The results of this study suggest the importance of counting small MPs when determining their abundances in groundwater or their abundances would be considerably underestimated. The present study for the first time demonstrated the occurrence of MPs in groundwater in China, which improves our understanding of the MPs distribution and raises concerns about groundwater safety in terms of MPs pollution.

Hydrogeochemical Processes and Potential Exposure Risk of Arsenic-Rich Groundwater from Huaihe River Plain, China

Arsenic poses a danger to environmental health, and arsenic-rich groundwater is a key exposure risk for humans. The distribution, migration, and enrichment of arsenic in groundwater is an important environmental and public health problem. Currently, the Huaihe River Basin is identified as a region of arsenic-rich groundwater in China. This study aims to assess arsenic-rich groundwater potential pollution risk, analyze the hydrogeochemical processes, and trace the ion source based on an analysis of groundwater hydrogeochemical data. The results show that arsenic is the main inorganic chemical substances affecting the water quality in the study area, which presents a high exposure risk for public health. The arsenic concentration of groundwater was f 5.75 ± 5.42 μg/L, and 23% of the considered samples exceeded the drinking water standards of the World Health Organization. The groundwater in the study area underwent evaporation, halite dissolution, and ion exchange processes. The total alkalinity (HCO3−) of the arsenic-rich groundwater mainly ranged between 400–700 mg/L, and the chemical type was mainly of HCO3-Na. In an alkaline environment, the oxidative dissolution and reductive dissolution of arsenic bearing minerals might be the formation mechanism of arsenic-rich groundwater.

Fluoride contamination, spatial variation, and health risk assessment of groundwater using GIS: a high-density survey sampling in Weifang City, North China.

The present study, with the aid of GIS, utilizes high-density groundwater (GW) sampling data (1398 samples) to analyze the spatial variation characteristics of GW fluoride in Weifang City (WFC), and evaluate the health risks associated with drinking water routes. The concentration of fluoride in the GW of WFC is observed to be between 0.08 and 9.16mg/L, with a mean value of 0.62mg/L. The fluoride concentration of a total of 192 GW samples exceeded the limit of China's GW quality standards (1mg/L), accounting for 14.74%. The GW fluoride concentration in most areas of WFC is less than 1mg/L. However, the relatively high-value zones are mostly concentrated in the upper reaches of Wen River, the east of Shouguang, the southeast of Anqiu, the east of Qingzhou, the east of Fangzi, and the southeast and northwest of Gaomi. The hydrochemical types of GW in WFC are mostly HCO3-Ca·Mg and SO4·Cl-Ca·Mg, while GW samples with hydrochemical types HCO3-Na and SO4·Cl-Na are characterized by high fluoride content. The hydrochemical characteristics of GW in WFC are mostly dominated by rock weathering. In addition, the northern coastal plain is evidently influenced by seawater intrusion. The concentration of fluoride in GW is affected by the dissolution of fluorine-containing minerals, cation exchange, and alkaline environmental factors. The effect of GW by seawater intrusion and very high content of Na+ will decrease the fluoride content of the GW through cation exchange. Health risk assessment demonstrated that the mean values of non-carcinogenic hazard quotient (HQ) for infants, children, teenagers, and adults were 0.52, 0.35, 0.31, and 0.30, respectively. In addition, the distribution characteristics of GW fluoride in high health risk areas (HQ > 1) in WFC are further consistent with the spatial variation of GW fluoride content. Overall, the health risk distribution area of GW fluoride in WFC is decreasing in the following order: infants > children > teenagers > adults.

Prediction modeling of geogenic iodine contaminated groundwater throughout China

Geogenic iodine-contaminated groundwater represents a threat to public health in China. Identifying high-iodine areas is essential to guide the mitigation of this problem. Considering that traditional analytical techniques for iodine testing are generally time-consuming, laborious, and expensive, alternative methods are needed to supplement and enhance existing approaches. Therefore, we developed an artificial neural network (ANN) model and assessed its feasibility in terms of predicting high iodine levels in groundwater in China. A total of 22 indicators (including climate, topography, geology, and soil properties) and 3185 aggregated samples (measured groundwater iodine concentrations) were utilized to develop the ANN model. The results showed that the accuracy and area under the receiver operating characteristic curve of the model on the test dataset are 90.9% and 0.972, respectively, and climate and soil variables are the most effective predictors. Based on the prediction results, a high-resolution (1-km) nationwide prediction map of high-iodine groundwater was produced. The high-risk areas are mainly concentrated in the central provinces of Henan, Shaanxi, and Shanxi, the eastern provinces of Henan, Shandong, and Hebei, and the northeastern provinces of Liaoning, Jilin, and Heilongjiang. The total number of people estimated to potentially be at high-risk areas because they use untreated high-iodine groundwater as drinking water is approximately 30 million. Considering the growing demand for groundwater in China, this work can guide the prioritization of groundwater contamination mitigation efforts based on regional groundwater quality levels to enhance environmental management.

Analysis of Spatiotemporal Groundwater-Storage Variations in China from GRACE

In China, where some regions are over-reliant on groundwater, groundwater consumption is faster than replenishment, which results in a continuous decrease in the groundwater level. Here, we applied spatial and temporal methods to analyze the spatiotemporal variations in groundwater in China from GRACE, GRACE-FO, and GLDAS data. From a national perspective, groundwater storage showed a decreasing trend in northern China and an increasing trend in southern China. The results showed that the rates of groundwater depletion in North China, the Loess Plateau, and Northwest China were −10.09 ± 0.94, −10.05 ± 1.05, and –4.91 ± 0.28 mm y−1 equivalent height of water from 2003 to 2019, respectively. Furthermore, the groundwater in South China, the middle-lower Yangtze River, and the Ch-Yu region had a positive trend, with rates of 7.26 ± 1.51, 7.73 ± 1.35, and 3.61 ± 0.53 mm y−1 equivalent height of water, respectively. We also found that groundwater storage fluctuated slightly before 2016 on the Qinhai-Tibet Plateau and in Northeast China and decreased significantly after 2016. The Yun-Gui Plateau had a fluctuating trend. Investigating the spatiotemporal variation in groundwater storage in China can provide data for initiating regional ecological and environmental protection.

Comparison of characteristics, water quality and health risk assessment of trace elements in surface water and groundwater in China

Water quality is closely associated with human health and socio-economic sustainable development. With the increasingly intensive anthropogenic activities, pollutants especially trace elements, enter water aquatic system and cause harm to humans. This study conducted the first systematic comparison on the pollution status of surface water and groundwater in China. Water quality and health risk assessment of 12 trace elements were evaluated according to the water quality index (WQI), hazard quotient (HQ), hazard index (HI), and carcinogenic risk (CR). The results showed that the average values of trace elements in the majority of surface water were higher than those in groundwater. The WQI values demonstrated that 86.02% of surface water and 83.11% of groundwater were suitable for drinking water. Arsenic served as the predominant pollutant and contributed significantly to cause the non‑carcinogenic risk on human health in both surface water and groundwater, children were more vulnerable to the adverse effects than adults. In surface water, the priority non-carcinogenic risk sites were mainly distributed in Anning River, Taizi River, Middle reaches of Huai River and Jilin section of Songhua River. For groundwater, the high-risk sites were located in Huhhot Basin, Kuitun, Jianghan Plain, Datong Basin and Yucheng County. Arsenic posed potential carcinogenic risk to local resident in some water sites, and it presented higher in groundwater than surface water. More concerns should be paid on Songhua, Yangtze and Huai River Basins, in addition, Pearl, Southeast Coastal, Southwest and Northwest River Basins still need attention. The future work should be carried out more extensive range of the water sites and long-term monitoring in China. In particular, more attention should be dedicated to assess high As water bodies.

Evaluating the genesis and dominant processes of groundwater salinization by using hydrochemistry and multiple isotopes in a mining city

The increasing salinization of groundwater renders it challenging to maintain the water quality. Moreover, knowledge regarding the characteristics and mechanism of groundwater salinization in mining areas remains limited. This study represents the first attempt of combining the hydrochemical, isotope (δD, δ18O, δ37Cl, and 87Sr/86Sr) and multivariate statistical analysis methods to explore the origin, control, and influence of fluoride enrichment in mining cities. The TDS content of groundwater ranged from 275.9 mg/L to 2452.0 mg/L, and 54% of the groundwater samples were classified as class IV water according to China's groundwater quality standards (GB/T 14848–2017), indicating a decline in the water quality of the study area. The results of the groundwater ion ratio and isotope discrimination analysis showed that dissolution and evaporation involving water-rock interactions and halite were the main driving processes for groundwater salinization in the study area. In addition to the hydrogeological and climatic conditions, mine drainage inputs exacerbated the increasing salinity of the groundwater in local areas. The mineral dissolution, cation exchange, and evaporation promoted the F− enrichment, while excessive evaporation and salinity inhibited the F− enrichment. Gangue accumulation and infiltration likely led to considerable F− enrichment in individual groundwater regions. Extensive changes in the groundwater salinity indicated differences in the geochemical processes that controlled the groundwater salinization. Given the particularity of the study area, the enrichment of salinization and fluoride triggered by mining activities cannot be ignored.

The Impacts of the Geographic Distribution of Manufacturing Plants on Groundwater Withdrawal in China

The overexploitation of groundwater in China has raised concern, as it has caused a series of environmental and ecological problems. However, far too little attention has been paid to the relationship between groundwater use and the spatial distribution of water users, especially that of manufacturing factories. In this study, a factory scatter index (FSI) was constructed to represent the spatial dispersion degree of manufacturing factories in China. It was found that counties and border areas between neighboring provinces registered the highest FSI increases. Further non-spatial and spatial regression models using 205 provincial-level secondary river basins in China from 2016 showed that the scattered distribution of manufacturing plants played a key role in groundwater withdrawal in China, especially in areas with a fragile ecological environment. The scattered distribution of manufacturing plants raises the cost of tap water transmission, makes monitoring and supervision more difficult, and increases the possibility of surface water pollution, thereby intensifying groundwater withdrawal. A reasonable spatial adjustment of manufacturing industry through planning and management can reduce groundwater withdrawal and realize the protection of groundwater. Our study may provide a basis for water-demand management through spatial adjustment in areas with high water scarcity and a fragile ecological environment.