Dehbandi Reza, Moore Farid, Keshavarzi Behnam
Department of Earth Sciences, College of Sciences, Shiraz University, Shiraz, 71454, Iran.
Department of Earth Sciences, College of Sciences, Shiraz University, Shiraz, 71454, Iran.
Chemosphere. 2018 Feb;193:763-776. doi: 10.1016/j.chemosphere.2017.11.021. Epub 2017 Nov 20.
The present study is the first attempt to put forward the possible source(s) and health risk assessment of fluoride in Bahabad, central Iran. Fluoride concentrations ranged from 0.22 to 2.35 mg/L and 292-355 mg/kg in the groundwater and soil samples, respectively. Geochemical provenance techniques using major and rare earth elements in soils revealed that local shale is the most probable source rock of fluoride in the area. A two-step chemical fractionation method applied on soil samples demonstrated that residual and water-soluble fractions were the most probable modes of fluoride in soil, whereas exchangeable fraction had a minor role. The coefficient of aqueous migration showed that fluoride in the studied soils behaved as a mobile element. Moreover, the relative mobility indicated that soils played a more important role than rocks in releasing fluoride into groundwater. In groundwater medium, chemical weathering, evaporation, and ion exchange acted as the main geochemical controlling factors of fluoride enrichment. Findings of this study signify that the role of NaCl and NaSO-type waters should be considered more to recognize susceptible areas to fluoride contamination in groundwater. People in the study area are exposed to high levels of fluoride intake through drinking water, thus making dental fluorosis a major public health concern in the area. Scanning electron microscopy of the dentin's enamel showed morphological modifications (e.g., cracks and fissures) in residents' enamel structures. The results of this study may lead to suitable management strategies to mitigate the endemic fluorosis problem.
本研究首次尝试提出伊朗中部巴哈巴德氟化物的可能来源及健康风险评估。地下水和土壤样品中的氟化物浓度分别为0.22至2.35毫克/升和292 - 355毫克/千克。利用土壤中的主要元素和稀土元素的地球化学溯源技术表明，当地页岩是该地区氟化物最可能的源岩。对土壤样品采用两步化学分级方法表明，残留态和水溶态是土壤中氟化物最可能的存在形态，而交换态的作用较小。水迁移系数表明，研究土壤中的氟化物表现为可移动元素。此外，相对迁移率表明，土壤在向地下水中释放氟化物方面比岩石发挥着更重要的作用。在地下水介质中，化学风化、蒸发和离子交换是氟化物富集的主要地球化学控制因素。本研究结果表明，应更多地考虑NaCl和NaSO型水的作用，以识别易受地下水氟化物污染的区域。研究区域的人们通过饮用水摄入高水平的氟化物，因此氟斑牙成为该地区主要的公共卫生问题。牙本质釉质的扫描电子显微镜显示居民釉质结构存在形态学改变（如裂纹和裂隙）。本研究结果可能会带来合适的管理策略，以减轻地方性氟中毒问题。
