Health risks from groundwater arsenic on residents in northern China coal-rich region

Determination of high-risk factors and related spatially influencing variables of heavy metals in groundwater

Identifying high-risk factors (heavy metals (HMs) and pollution sources) by coupling receptor models and health risk assessment model (HRA) is a novel approach within the field of risk assessment. However, this coupled model ignores the contribution of spatial differentiation to high-risk factors, resulting in the assessment being subjective. Taking Dongting Plain (DTP) as an example, a coupling framework by jointly using the positive matrix factorization model (PMF), HRA, Monte Carlo simulation, and geo-detector was developed, aiming to identify high-risk factors in groundwater, and further explore key environmental variables influencing the spatial heterogeneity of high-risk factors. The results showed that at least 82.86 % of non-carcinogenic risks and 97.41 % of carcinogenic risks were unacceptable for people of all ages, especially infants and children. According to the relationships among HMs, pollution sources, and health risks, As and natural sources were defined as high-risk HMs and sources, respectively. The interactions among Holocene thickness, oxidation-reduction potential, and dissolved organic carbon emerged as the primary drivers of spatial variability in high-risk factors, with their combined explanatory power reaching up to 74%. This proposed framework provides a scientific reference for future studies and a practical reference for environmental authorities in developing effective pollution management measures.

Steady-state analysis of social responsibility strategy of coal power enterprises from the perspective of game theory

Under the dual-carbon background, coal power enterprises are required to actively fulfill their social responsibility in order to achieve energy saving and emission reduction as soon as possible. Considering the uncertainty of the external environment and the potential conflict of interest of the key stakeholders in the fulfillment of corporate social responsibility, coal power enterprises are not always positive in fulfilling their social responsibility. This paper combines prospect theory and mental account theory with evolutionary game to construct an evolutionary game model involving coal power enterprises, government regulators and the public to study the social responsibility behavior of coal power enterprises. The results of the study show that: (1) The social responsibility behavior of coal power enterprises under the dual-carbon background is a typical cost-driven behavior, and coal power enterprises are more sensitive to costs compared to benefits. (2) The formulation of regulatory policies by government regulators largely depends on the decision inertia of coal power enterprises, and the formulation of regulatory policies by government regulators will also affect the decision inertia of coal power enterprises. (3) The public's strategic choices do not entirely depend on the strategic choices of coal and power enterprises and government regulators, and are more closely related to the setting of the reference point. (4) In addition to the realistic factors, the subjective factors of decision makers are also important factors affecting the fulfillment of social responsibility of coal and power enterprises. Based on the results of the study, this paper proposes countermeasures to enhance the internal driving force of coal power enterprises to fulfill their social responsibility behaviors from the aspects of establishing a communication mechanism, improving the reward and punishment system, and strengthening risk management.

Monthly variations of groundwater arsenic risk under future climate scenarios in 2081-2100

The seasonal variations of shallow groundwater arsenic have been widely documented. To gain insight into the monthly variations and mechanisms behind high groundwater arsenic and arsenic exposure risk in different climate scenarios, the monthly probability of high groundwater arsenic in Hetao Basin was simulated through random forest model. The model was based on arsenic concentrations obtained from 566 groundwater sample sites, and the variables considered included soil properties, climate, topography, and landform parameters. The results revealed that spatial patterns of high groundwater arsenic showed some fluctuations among months under different future climate scenarios. The probability of high total arsenic and trivalent arsenic was found to be elevated at the start of the rainy season, only to rapidly decrease with increasing precipitation and temperature. The probability then increased again after the rainy season. The areas with an increased probability of high total arsenic and trivalent arsenic and arsenic exposure risk under SSP126 were typically found in the high-arsenic areas of 2019, while those with decreased probabilities were observed in low-arsenic areas. Under SSP585, which involves a significant increase in precipitation and temperature, the probability of high total arsenic and trivalent arsenic and arsenic exposure risk was widely reduced. However, the probability of high total arsenic and trivalent arsenic and arsenic exposure risk was mainly observed in low-arsenic areas from SSP126 to SSP585. In conclusion, the consumption of groundwater for human and livestock drinking remains a threat to human health due to high arsenic exposure under future climate scenarios.

Hydrochemical characteristics and water quality assessment of natural water in the South China Mountains: the case in Lianzhou

South China Mountain Region has a well-developed water system with the most abundant water in China. Untreated natural water is the main source of drinking water for the local people. This study aimed to investigate the hydrochemical characteristics and trace element concentrations of natural water in the mountainous regions of South China. In this study, 116 water samples were collected. Traditional hydrochemical methods, water quality index (WQI), hazard index (HI), and nutrient speciation of trace elements (NSTE) were used for analysis. In general, the hydrochemical type was mainly Ca-HCO3- type. The hydrochemical characteristics were mainly influenced by the weathering of calcite and silicate rocks. Overall total dissolved solids (TDS) were low, indicating mainly soft and very soft water. The water that met the standards for mineral water had an average concentration of 59.69 mg/L for Sr (strontium) and an average concentration of 0.46 mg/L for H2SiO3 (silicic acid). Although the water quality index (WQI) indicated that 91.3% of the water samples in the study area were of good quality (WQI < 25), 2.58% of the water samples had significant non-carcinogenic risk (HI > 1) due to the high As and Pb concentrations. The water in the study area contributed significantly to human intake of Sr, Cr, and V, accounting for 8.4, 8.3, and 7.7% of the required daily intake for adults, respectively. It is recommended that a comprehensive water quality evaluation system be constructed to ensure that mountain water is managed for development and safe to drink.

A hydrochemical and isotopic approach for source identification and health risk assessment of groundwater arsenic pollution in the central Yinchuan basin

Arsenic contamination of groundwater is becoming a major global issue as it can severely affect the safety of drinking water and human health. In this paper, 448 water samples were investigated to study the spatiotemporal distribution, source identification and human health risk of groundwater arsenic pollution in the central Yinchuan basin by applying a hydrochemical and isotopic approach. The results showed that arsenic concentrations in groundwater ranged from 0.7 μg/L to 26 μg/L with a mean of 2.19 μg/L, and 5.9% of samples were above 5 μg/L, indicating the arsenic pollution of groundwater in the study area. High arsenic groundwater was mainly distributed in the northern and eastern areas along the Yellow river. The main hydrochemistry type of high arsenic groundwater was HCO3·SO4-Na·Mg, and the dissolution of arsenic-bearing minerals in sediment, irrigation water infiltration and aquifer recharge from the Yellow river were the main sources of arsenic in groundwater. The arsenic enrichment was dominantly controlled by the TMn redox reaction and the competitive adsorption of HCO3-, and the influence of anthropogenic activities was limited. The health risk assessment suggested that the carcinogenic risk of As for children and adults greatly exceeded the acceptable risk threshold of 1E-6, displaying a high carcer risk, while the non-carcinogenic risks of As, F-, TFe, TMn and NO3- in 2019 were largely higher than the acceptable risk threshold (HQ > 1). The present study provides insight into the occurrence, hydrochemical processes and potential health risk of arsenic pollution in groundwater.

Spatio-temporal variation of groundwater pollution in urban wetlands and management strategies for zoning

Groundwater is an important resource to maintain the sustainable development of urban wetlands. The Jixi National Wetland Park (JNWP) was studied to realize the refined prevention and control of groundwater. The self-organizing map-K-means algorithm (SOM-KM), improved water quality index (IWQI), health risk assessment model and forward model were used comprehensively to evaluate the groundwater status and solute sources in different periods. The results showed that the groundwater chemical type in most areas was the HCO₃-Ca type. Groundwater chemistry data from different periods were clustered into five groups. Groups 1 and 5 are affected by agricultural and industrial activities, respectively. The IWQI value in the normal period was higher in most areas due to the influence of spring ploughing. The east side of the JNWP was disturbed by human activities, and the quality of drinking water continued to deteriorate from the wet period to the dry period. 64.29% of the monitoring points showed good irrigation suitability. The health risk assessment model showed that the health risk was the largest in the dry period and the smallest in the wet period. The main factors causing health risks in the wet period and other periods were NO₃^- and F^-, respectively. The overall cancer risk was within acceptable limits. The forward model and ion ratio analysis showed that the weathering of carbonate rocks was the main factor affecting the evolution of groundwater chemistry, accounting for 67.16%. The high-risk areas of pollution were mainly concentrated in the east of the JNWP. K⁺ and Cl^- were the key monitoring ions in the risk-free zone and potential risk zone, respectively. The research can be used to help decision-makers carry out fine zoning control of groundwater.

Impacts of high-quality coal mine drainage recycling for replenishment of aquatic ecosystems in arid regions of China: Bacterial community responses

Coal mine water is usually recycled as supplementary water for aquatic ecosystems in arid and semiarid mining regions of China. To ensure ecosystem health, the coal mine water is rigorously treated using several processes, including reverse osmosis, to meet surface water quality standards. However, the potential environmental impacts of this management pattern on the ecological function of receiving water bodies are unclear. In this study, we built several microcosm water ecosystems to simulate the receiving water bodies. High-quality treated coal mine drainage was mixed into the model water bodies at different concentrations, and the sediment bacterial community response and functional changes were systematically investigated. The results showed that the high-quality coal mine drainage could still shape bacterial taxonomic diversity, community composition and structure, with a concentration threshold of approximately 50%. Moreover, both the Mantel test and the structural equation model indicated that the salinity fluctuation caused by the receiving of coal mine drainage was the primary factor shaping the bacterial communities. 10 core taxa in the molecular ecological network influenced by coal mine drainage were identified, with the most critical taxa being patescibacteria and g_Geothermobacter. Furthermore, the pathway of carbohydrate metabolism as well as signaling molecules and interactions was up-regulated, whereas amino acid metabolism showed the opposite trend. All results suggested that the complex physical-chemical and biochemical processes in water ecosystems may be affected by the coal mine drainage. The bacterial community response and underlying functional changes may accelerate internal nutrient cycling, which may have a potential impact on algal bloom outbreaks.

Characterizing spatial dependence of boron, arsenic, and other trace elements for Permian groundwater in Northern Anhui plain coal mining area, China, using spatial autocorrelation index and geostatistics

Anthropogenic and geological factors play an essential role in the variability of groundwater quality, resulting in a weak spatial dependence of groundwater trace elements. Thus, it is an essential study to investigate the factors affecting groundwater quality and its spatial abundance of trace elements (including As, B, and other metalloids). In this study, samples are obtained from a Permian sandstone fracture aquifer in a coal mining area. A multivariate statistical analysis, hydrogeochemistry modeling, and spatial autocorrelation analysis were used to analyze the data. The results showed that Moran index was positive for all trace elements, which had good spatial autocorrelation. The Local indicators of spatial association (LISA) indicated that trace elements were clustered. The hydrogeochemical modeling results indicated that the precipitation and stability of iron-phase minerals, such as rhodochrosite and arsenic (As) absorption on the surface of iron-phase minerals in the aquifer, may limit concentrations in the southern region. The spatial autocorrelations of both As and Boron (B) were positive (high-high) in the western areas, indicating that As contamination occurred from both natural geological causes and human coal mining activities. In contrast, B contamination was mainly linked to the influence of human agricultural or industrial activities. Over 96% of the groundwater concentrations of As (10 μg/L) and B (300 μg/L) in the study area exceeded World Health Organization (WHO) limits. Overall, the results of this work could help decision-makers involved in regional water quality management visualize disperse zones where specific anthropogenic and geological processes may threaten groundwater quality.

Health risks of shallow groundwater in the five basins of Shanxi, China: Geographical, geological and human activity roles

Rapid economic development often leads to groundwater degradation, posing health risks to those who rely on it. The groundwater discharge conditions in basins are poor. The health risk of shallow groundwater in basins needs more attentions. The health risk of shallow groundwater in the five basins of Shanxi Province, China was discussed based on the hydrochemical evolution of shallow groundwater and the water quality assessment. The results showed that arsenic (As) and chromium (Cr) in the shallow groundwater of the basins caused prominent health risks followed by fluoride (F) and nitrate (NO₃^-). The non-carcinogenic risks of As, F and NO₃- to children were higher than that to adults, and the carcinogenic risks of As and Cr were higher for adults than children. Various hydrogeochemical reactions, geological conditions, climatic factors, and human activities are closely related to groundwater health risks, and basin topography is considered as one of key factors. Water-rock interaction, dedolomitization and cation exchange are the natural processes in the evolution of groundwater hydrochemistry, while agricultural and mining activities are the anthropogenic factors causing groundwater degradation. The leaching/dilution effects of infiltration precipitation in the basin-mountain systems cause distinct temporal changes in the chemical composition and health risks of the groundwater in the basins. Differences in climate and farming practices among the basins further complicate the spatio-temporal changes. The basin-mountain system is conducive to the convergence and enrichment of water flow and solutes in the basins, which aggravates the degradation of groundwater quality. This study highlights that the combined influences of geographical and geological factors and anthropogenic activities amplify the human health risks of groundwater in the basins.

Association between gestational arsenic exposure and intrauterine growth restriction: the role of folate content

Gestational arsenic (As) exposure is associated with intrauterine growth restriction (IUGR). This study explored the association among gestational As exposure, IUGR, and reduction of folate content in maternal and umbilical plasma from 530 mother-and-singleton-offspring pairs. Birth weight (BW) was negatively correlated with As in maternal plasma (r=-0.194, P<0.001) and umbilical plasma (r=-0.235, P<0.001). By contrast, a positive correlation was found between BW and maternal folate content (r=0.198, P<0.001). The subjects were divided into As-L and As-H groups. The influence of As-H on small for gestational age (SGA) infants, a marker of IUGR, was evaluated by multivariate logistic regression that excludes interferences of gestational age, infant sex, and other confounding factors. Mothers with As-H had an elevated risk of SGA infants (adjusted OR, 2.370; P<0.05). Interestingly, maternal folate content was lower in subjects with As-H than those with As-L (22.4±10.7 vs 11.2±6.7 nmol/L, P<0.001). Linear correlation models show that As level was negatively correlated with folate content in maternal plasma (r=-0.615, P<0.001) and umbilical plasma (r=-0.209, P<0.001). Moreover, maternal folate reduction has an obvious mediating effect between increased As and decreased BW (β=-0.078, P<0.05). Our results indicate that folate reduction may be a mediator between gestational As exposure and IUGR.

Remote-Sensing Evaluation and Temporal and Spatial Change Detection of Ecological Environment Quality in Coal-Mining Areas

The large-scale development and utilization of coal resources have brought great challenges to the ecological environment of coal-mining areas. Therefore, this paper has used scientific and effective methods to monitor and evaluate whether changes in ecological environment quality in coal-mining areas are helpful to alleviate the contradiction between human and nature and realize the sustainable development of such coal-mining areas. Firstly, in order to quantify the degree of coal dust pollution in coal-mining areas, an index-based coal dust index (ICDI) is proposed. Secondly, based on the pressure-state-response (PSR) framework, a new coal-mine ecological index (CMEI) was established by using the principal component analysis (PCA) method. Finally, the coal-mine ecological index (CMEI) was used to evaluate and detect the temporal and spatial changes of the ecological environment quality of the Ningwu Coalfield from 1987 to 2021. The research shows that ICDI has a strong ability to extract coal dust with an overall accuracy of over 96% and a Kappa coefficient of over 0.9. As a normalized difference index, ICDI can better quantify the pollution degree of coal dust. The effectiveness of CMEI was evaluated by four methods: sample image-based, classification-based, correlation-based, and distance-based. From 1987 to 2021, the ecological environment quality of Ningwu Coalfield was improved, and the mean of CMEI increased by 0.1189. The percentages of improvement and degradation of ecological environment quality were 71.85% and 27.01%, respectively. The areas with obvious degradation were mainly concentrated in coal-mining areas and built-up areas. The ecological environment quality of Pingshuo Coal Mine, Shuonan Coal Mine, Xuangang Coal Mine, and Lanxian Coal Mine also showed improvement. The results of Moran’s Index show that CMEI has a strong positive spatial correlation, and its spatial distribution is clustered rather than random. Coal-mining areas and built-up areas showed low–low clustering (LL), while other areas showed high–high clustering (HH). The utilization and popularization of CMEI provides an important reference for decision makers to formulate ecological protection policies and implement regional coordinated development strategies.

Arsenic exposure analysis for children living in central China: From ingestion exposure to biomarkers

Emerging evidence indicates that chronic low-dose arsenic (As) exposure can pose adverse health effects to children. This study aimed to systematically study the exposure risk induced by As ingestion in children living in Hubei Province, central China. The feasibility of first morning spot urine instead of 24-h urine as an environmental exposure biomarker was also explored. A total of 120 children aged 2-17 years were recruited from an urban area for the collection of biomarker samples (first morning and 24-h urine samples), environmental exposure samples (duplicate diets, drinking water, and soil), and related child-specific exposure factors. The external exposure risk, internal exposure level, and source of exposure to As in children were analyzed. The results indicated that As concentration in duplicated diets, water, and soil were 29.2 μg kg^-1, 1.3 μg L^-1, and 9.3 mg kg^-1, respectively; these were all below the corresponding maximum allowable levels in China (the threshold value of As in most food, drinking water and soil are 0.5 mg⸱kg^-1, 0.01 mg L^-1, and 20 mg⸱kg^-1, respectively). Dietary intake was the predominant exposure route, accounting for 90% of the total daily dose. The combined oral non-carcinogenic and carcinogenic risks all exceeded the corresponding maximum acceptable risk level. Therefore, As bioavailability should be investigated and used in health risk assessment. Multiple linear regression analysis indicated that urinary As was positively associated with dietary As, with a one-unit increase in daily As intake from the diet associating with 4.82 and 5.21 μg g^-1 increases in 24-h urine and first morning urine, respectively. Furthermore, significant correlations with 24-h urine and external exposure metrics suggested that creatine-adjusted As concentrations in first morning urine could be an appropriate substitute of 24-h urine as exposure biomarkers.

Pedo-geochemical background and sediment contamination of metal(loid)s in the old mining-district of Salsigne (Orbiel valley, France)

The mining district of Salsigne in the Orbiel valley (Aude, France) was at one time the first gold mine in Europe and the first arsenic mine in the world. However, no scientific studies have evaluated the magnitude of its environmental impact. In this study, the pedo-geochemical background (PGB) was determined for 14 metal (loid) elements, including As. It appears that the PGB values for As and Sb are relatively high with 44±12 and 0.9±1.2 mg kg^-1, respectively, because of the geological particularities of this area. In a second step, these PGB values (normalized with Ti concentrations) were used as local references to determine enrichment factors (EFs) of bed river sediments for the Orbiel River and two of its major tributaries (Gresillou and Russec rivers) collected between November 2018 and July 2020. Results showed that riverine sediments are contaminated by past mining activity and/or current storage areas. If we except the major elements (Fe, Ti and at a lesser extent Mn), we observed that As, Cu, Sb, Pb present the highest concentrations relative to the remaining elements (Cd, Co, V, Ni and Cr). In the case of As, EFs can reach 74 in the Orbiel River, 1000 in the Gresillou River and 27 in the Russec River. These calculations were also performed for sediments transported by the extreme flood of October 14, 2018, that killed 15 people and potentially remobilized contamination in the valley. We observed that the As concentrations of suspended samples from Grésillou and Russec rivers have reached 870 mg kg^-1. Finally, the As concentrations measured in the river sediments of this valley are of the same order of magnitude than those published in the literature for environments strongly impacted by mining or mineral processing activities.

Ultra-Performance Liquid Chromatography-Tandem Mass Spectrometry for the Analysis of Complex Compounds in Serum and Its Application in Accurate Detection of Early Arsenic Exposure

With the acceleration of industrialization, environmental arsenic pollution is threatening human health. However, by the time clinical symptoms appear, arsenic toxicity has usually caused irreversible damage to the body, so it is important to establish a rapid and accurate screening method for early arsenic exposure. In this work, 32 female C57BL/6 mice were exposed to different concentrations of inorganic arsenic in drinking water for a week. By analyzing the changes in serum, more than 20 compounds were detected to increase or decrease with the increase of arsenic intake. The abnormal increase in inosine, xanthine, xanthosine, and hypoxanthine and the abnormal purine pathway were found at the same time. Dimethylarsenic acid, an important inorganic arsenic metabolite in the body, was also found in serum. Combined with statistical analysis, early arsenic exposure can be easily and quickly detected, and the potential health risks of short-term exposure can be revealed simultaneously.