In Arusha urban, northern Tanzania, groundwater contributes about 80% of the water supply. However, elevated fluoride levels and evidence of anthropogenic pollution have been reported in the groundwater around Mount Meru which is a water source for Arusha urban. This study aims at understanding the recharge areas and flow pathways of groundwater in what has been a poorly monitored area. The study uses the isotopic ratio of oxygen and hydrogen to estimate the groundwater recharge area and flow pathway. The results show the recharge elevation of groundwater is between 1,800 and 3,500 m above mean sea level on the slopes of Mount Meru. The average fluoride contents in the study area are 5.3± 0.4 mg/L greater than the limits of 1.5 mg/L set by the World Health Organization (WHO) and Tanzania. The nitrate concentration of 83.9 mg/L at the lower elevation areas (<1,400 m above mean sea level) exceeds the 50 mg/L WHO limit. The relationship of F with δO and NO3 suggests the leaching of fluoride in high altitudes and dilution in lower altitudes.

中文翻译：

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坦桑尼亚北部阿鲁沙含水层补给区评价：水同位素示踪剂的应用

在坦桑尼亚北部的阿鲁沙市区，地下水约占供水量的 80%。然而，据报道，梅鲁山周围的地下水中氟化物含量升高，并且存在人为污染的证据，梅鲁山是阿鲁沙城市的水源。本研究旨在了解监测不足的地区地下水的补给区和流动路径。该研究利用氧和氢的同位素比来估算地下水补给面积和流动路径。结果表明，梅鲁山斜坡地下水补给高程在平均海平面以上 1,800 至 3,500 m 之间。研究区域的平均氟化物含量为 5.3±0.4 mg/L，高于世界卫生组织 (WHO) 和坦桑尼亚设定的 1.5 mg/L 限值。硝酸盐浓度为83。低海拔地区（平均海平面以上 <1,400 m）的 9 mg/L 超过了 WHO 的 50 mg/L 限值。F 与 δO 和 NO3 的关系表明氟化物在高海拔地区浸出而在低海拔地区稀释。