Department of Environmental Sciences, University of Peshawar, Peshawar 25120, Pakistan; Hydrogeochemistry Laboratory, Department of Environmental Sciences, Faculty of Biological Sciences, Quaid-i-Azam University, Islamabad, PO 45320, Pakistan.
Key Laboratory of Surficial Geochemistry, Ministry of Education, School of Earth Sciences and Engineering, Nanjing University, Nanjing 210023, China.
Sci Total Environ. 2018 Sep 1;635:203-215. doi: 10.1016/j.scitotenv.2018.04.064. Epub 2018 Apr 24.
This study investigated the fluoride (F) concentrations and physicochemical parameters of the groundwater in a fluorite mining area of the flood plain region of the River Swat, with particular emphasis on the fate and distribution of F and the hydrogeochemistry. To better understand the groundwater hydrochemical profile and F enrichment, groundwater samples (n=53) were collected from shallow (24-40m), mid-depth (48-65m) and deep (85-120m) aquifers, and then analysed using an ion-selective electrode. The lowest F concentration (0.7mg/L) was recorded in the deep-aquifer groundwater, while the highest (6.4mg/L) was recorded in shallow groundwater. Most groundwater samples (62.2%) exceeded the guideline (1.5mg/L) set by the World Health Organization (WHO); while for individual sources, 73% of shallow-groundwater samples (F concentration up to 6.4mg/L), 42% of mid-depth-groundwater samples, and 17% of deep-groundwater samples had F concentrations that exceeded this permissible limit. Assessment of the overall quality of the groundwater revealed influences of the weathering of granite and gneisses rocks, along with silicate minerals and ion exchange processes. Hydrogeochemical analysis of the groundwater showed that Na is the dominant cation and HCO the major anion. The anionic and cationic concentrations across the entire study area increased in the following order: HCO>SO>Cl>NO>F>PO and Na>Ca>Mg>K, respectively. Relatively higher F toxicity levels were associated with the NaHCO water type, and the chemical facies were found to change from the CaHCO to (NaHCO) type in calcium-poor aquifers. Thermodynamic considerations of saturation indices indicated that fluorite minerals play a vital role in the prevalence of fluorosis, while under-saturation revealed that - besides fluorite minerals - other F minerals that are also present in the region further increase the F concentrations in the groundwater. Finally, a health risk assessment via Dean's classification method identified that the groundwater with relatively higher F concentrations is unfit for drinking purposes.
本研究调查了斯瓦特河洪泛区萤石矿区地下水的氟（F）浓度和理化参数，特别关注 F 的归宿和分布以及水文地球化学。为了更好地了解地下水水化学特征和 F 富集，从浅层（24-40m）、中层（48-65m）和深层（85-120m）含水层中采集了 53 个地下水样本，并使用离子选择性电极进行了分析。深层地下水的 F 浓度最低（0.7mg/L），而浅层地下水的 F 浓度最高（6.4mg/L）。大多数地下水样本（62.2%）超过了世界卫生组织（WHO）设定的指导值（1.5mg/L）；而对于个别来源，浅层地下水样本中有 73%（F 浓度高达 6.4mg/L）、中层地下水样本中有 42%、深层地下水样本中有 17%的 F 浓度超过了这一允许限值。对地下水整体质量的评估表明，花岗岩和片麻岩以及硅酸盐矿物的风化和离子交换过程对地下水质量有影响。地下水的水文地球化学分析表明，Na 是主要阳离子，HCO 是主要阴离子。整个研究区的阴阳离子浓度依次增加：HCO>SO>Cl>NO>F>PO 和 Na>Ca>Mg>K。相对较高的 F 毒性水平与 NaHCO 水型有关，在钙贫含水层中，化学相从 CaHCO 型转变为（NaHCO）型。基于饱和指数的热力学考虑表明，萤石矿物在氟中毒的流行中起着至关重要的作用，而不饱和表明，除了萤石矿物外，该地区还存在其他 F 矿物，这进一步增加了地下水中的 F 浓度。最后，通过 Dean 分类法进行的健康风险评估表明，具有相对较高 F 浓度的地下水不适合饮用。
