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Unraveling the impact of high arsenic, fluoride and microbial population in community tubewell water around coal mines in a semiarid region: Insight from health hazards, and geographic information systems.
| Journal of Hazardous Materials | Rashid A, Ayub M, Gao X, Xu Y, Ullah Z, Zhu YG, Ali L, Li C, Ahmad A, Rinklebe J, Khan S, Ahmad P. | 480:136064.
Coal-F Endemic fluorosis areas Groundwater Industry Pakistan Age Arsenic Susceptible Populations Other

Abstract

Highlights

  • 24.6 % and 64 % of groundwater exceeded the WHO limit of As 10 µg/L, and F 1.5 mg/L.
  • High As and F– was observed in shallow aquifers around the coal minefield.
  • PMF model suggested five-factor solutions with better fitting of pollution sources.
  • Children aged between 6-14 years suffer from severe arsenicosis and fluorosis.
  • Montecarlo simulation and QMRI showed that children suffer from bacterial diseases.
High arsenic (As), fluoride (F–), and microbial pathogens coexist in semiarid conditions afflicting > 240 million people worldwide including Pakistan. Groundwater quality has declined due to geogenic and manmade activities providing suitable ground for ubiquity, bioavailability, and toxicity of contaminants. We tested the health hazard, distribution, and apportionment of As, F–, and microbes in groundwater around coal mines in Quetta, Pakistan. The range of As, and F– concentrations in groundwater were 0.2–16.6 µg/L, 0.4–18.5 mg/L. Both, As and F– correlate with high HCO3–, pH, Na+, SO42-, Fe, and Mn, and negatively with Ca2+ water. The coalfield showed many folds higher As 15.8–28.5 µg/L, and F– 10.8–34.5 mg/L compared to groundwater-wells. Geochemical phases revealed saturation of groundwater with calcite, dolomite, fluorite, gypsum, and undersaturation with halite-mirabilite, and arsenopyrite minerals. The positive matrix factorization (PMF) model assessed five-factor solutions: geogenic, industrial, coal mining, sulfide & fluoride-bearing mineral-dissolution, and agriculture pollution delivered As, F–, and microbial contamination. About 24.6 % and 64.4 % of groundwater samples exceeded the WHO guidelines of As 10 µg/L, F– 1.5 mg/L. The carcinogenicity, and non-carcinogenicity of As, and F– were higher in children than adults. Therefore, health hazards in children are of great concern in achieving sustainable management goals.

Introduction

Globally, the quality of groundwater is compromised by increased concentrations of arsenic (As), fluoride (F–), microbial pathogens viz. (T. Coliform, E. Coli, and F. Coli), and heavy metals (HMs), stemming from both geogenic and human-induced activities [1], [2], [3]. The geological release of As and F– is primarily linked to the weathering of granite, gneiss, and pegmatite rocks. Meanwhile, anthropogenic contributions to groundwater pollution include discharge from industrial processes, agricultural runoff, and effluents of coal mine deposits, all contributing to groundwater quality decline and associated health hazards [3], [4], [5]. Near coal mining areas, groundwater is particularly vulnerable to acid-mine drainage (AMD), which carries high concentrations of arsenic and fluoride, deteriorating the quality of water further [6]. The presence of environmental contaminants in groundwater, especially in regions with coal deposits, has been less explored, presenting a gap in understanding their impact on coal-based aquifers [7]. Groundwater, a crucial resource for domestic needs, when contaminated with high levels of As and F–, can lead to arsenicosis and fluorosis health issues. The World Health Organization (WHO) has set the guideline values for As 10 µg/L, F– 1.5 mg/L, and microbial pathogens at 0 CFU/L, to mitigate such risks [8].
More than 240 million people globally suffer from arsenicosis, with over 260 million affected by fluorosis [1], [9]. Notably, countries like Argentina [10], [11], Bangladesh [12], [13], Iran [14], [15], India [3], [16], Kenya [17], [18], Mexico [19], USA [20], and various nations in Africa [21] have reported high concentrations of As and F– in groundwater. In Pakistan alone, these contaminants impact approximately 60 million (As) and 13 million (F–) individuals [9], [22]. The occurrence of As and F– around AMD areas is contingent on the presence of As and F-bearing minerals. In the Quetta region, the local populace, particularly children living near coal mines, often rely on groundwater for drinking, exacerbating their exposure to these toxicants [23].
The quality of groundwater is influenced by several factors including regional geology, hydrogeological conditions, water-rock interactions, ion exchange, industrial effluents, agriculture practices, coal mining, and climatic variables [24], [25], [26], [27]. Approximately 80 % of waterborne diseases are attributed to microbial contamination [28], with around 65 % of water-related illnesses linked to fluoride exposure, leading to neurotoxicity, endocrine disruption, bone fracture, sexual disturbance, kidney failure, thyroid dysfunction, and cardiovascular problems [29], [30]. Microbial activity in groundwater can transform total arsenic into bioavailable and more toxic inorganic arsenic [1], [31], sometimes occurring alongside fluoride to heighten contamination risks during redox conditions influencing the solubility of fluorite minerals [32], [33], [34].
Addressing groundwater contamination by As, F–, and microbial pathogens necessitates comprehensive data evaluation [35], [36], [37]. Techniques such as positive-matrix factorization (PMF), factor analysis (FA), and geographic information system (GIS) are instrumental in deciphering the composition and hydrogeochemical dynamics of groundwater, facilitating the identification of contamination sources and pathways in aquifers around active coalfields [37], [38], [39]. The active coalfields of Degari-Sor are present 12 km to the south and cover an area of 50 km2 area extending up to 28 km towards the southeast side. Our research delves into the groundwater contamination challenges posed by high As, F–, and microbial pathogens in Quetta, Pakistan. We aim to (1) assess groundwater with elevated levels of As, F–, and microbial pollutants; (2) pinpoint the mineral saturation, and contamination sources through PMF modeling; and (3) evaluate spatial distribution patterns, and the health hazards posed by high levels of As, F–, and microbial populations. The insights gained from this study are intended to guide groundwater monitoring, quality, and management strategies to mitigate the prevalence of geogenic and anthropogenic inputs of arsenic, fluoride, and microbial contamination across affected regions.

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Section snippets

Geographic location and climate

Quetta, situated in the Baluchistan province of Pakistan, lies between latitudes 30.00°?30.50° N and longitudes 66.97°?67.15° E (Fig. 1a). This region is bordered by Dera Ismail Khan to the northeast, Dera Ghazi Khan and Sibi to the east, Sukkur and Jacobabad to the southeast, Karachi and Gwadar to the south, and Ziarat to the northeast. The climate of the area is semi-arid with annual precipitation (230–250 mm), and temperatures ranging from ?18.3 °C in winter to 42 °C in summer. The region is

Quantification and hydrogeochemical characteristics of groundwater

Table 1 and Fig. S1a present the hydrogeochemical findings of groundwater and coal-mine water samples from Quetta, Pakistan (Table 1). Groundwater shows variability over time, attributed to changes in various physicochemical parameters. These fluctuations are driven by both natural and human influences including coal mining practices [64]. The study compared groundwater’s hydrogeochemical characteristics, aligning the findings with the World Health Organization (WHO) standards [8].
The major

Conclusion

This study delves into the occurrence, prevalence, and enrichment of arsenic (As), fluoride (F–), and microbial pathogens in groundwater near coal mines in Quetta, Pakistan. It uncovering the unsuitability of shallow groundwater for drinking due to elevated concentrations of As, F–, and microbial pathogens. The investigation revealed that 24.6%, 64.4%, 82%, 72%, and 70% of groundwater samples surpassed the WHO guidelines for F– As, T. Coliform, E. Coli, and F. Coli, respectively. The presence

Environmental Implications

Chronic exposure to high arsenic (As) and fluoride (F–) groundwater has increased community arsenicosis and fluorosis problems in the people of Pakistan. Groundwater quality has declined due to geogenic inputs, industrial pollution, coal mining, sulfide and fluoride-bearing dissolution, and agriculture practices. The polluted groundwater systems with poor and unfit shallow aquifers required special treatment. The excessive ingestion of As>?10?µg/L and F–>?1.5?mg/L is considered detrimental…

CRediT authorship contribution statement

Xubo Gao: Writing – review & editing, Visualization, Supervision, Resources, Project administration, Funding acquisition, Formal analysis, Data curation, Conceptualization. Liaqat Ali: Visualization, Resources, Methodology, Investigation, Formal analysis, Data curation, Conceptualization. Yong Guan Zhu: Software, Project administration, Methodology, Formal analysis, Data curation, Conceptualization. Zahid Ullah: Methodology, Investigation, Formal analysis, Data curation, Conceptualization.

Declaration of Competing Interest

The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.

Acknowledgments

This research work has been financially supported National Natural Science Foundation of China (NSFC) with Young Scientists Programs (No: 42307066; 32301334), the Open Competition Mechanism to Select the Best Candidates Program (No: IUE-JBGS-202203) at the Institute of Urban Environment, Chinese Academy of Sciences (IUE, CAS), and the Ningbo S&T project (No: 2021-DST-004) at the Ningbo Science and Technology Bureau (NSTB), National Natural Science Foundation of China (Grant Nos. 41521001 and