地下水氟含量在一定程度上受控于钙离子含量，钙离子浓度越高，氟离子浓度就越低，反之亦然。可以认为，任何影响水中钙离子浓度的因素均有可能间接影响氟离子浓度。钙沉淀菌广泛存在于自然环境中，它能诱导碳酸钙沉淀的产生。高氟地下水中钙沉淀菌的分布如何，该类菌是否可以通过调节碳酸钙的沉淀反应速率来控制水中钙离子的浓度并最终影响水中氟离子的含量，人为抑制钙沉淀菌活性是否可以提高水中钙离子浓度进而降低氟离子浓度，针对这些问题展开研究有助于从另一各角度揭示高氟水的形成机制，有望为高氟地下水的治理提供新的选择。本课题拟从内蒙古镶黄旗高氟区地下水中分离钙沉淀菌，研究不同浓度的碳源条件下钙沉淀菌对碳酸钙沉淀动力学的影响，揭示钙沉淀菌对氟离子的沉淀和溶解反应平衡的控制规律及影响因素，结合高氟地下水水化学指标，微生物群落结构以及钙沉淀菌丰度等的时间和空间变化特征，探讨钙沉淀菌在高氟地下水的形成过程中的作用。

Fluorine is an essential trace element for human health. However, too much intake of fluoride would cause harmful effects on human health. Many parts of the world are suffering from fluoride pollution of drinking water. The content of fluoride in groundwater is in part controlled by the content of calcium ion. In most cases, the higher the concentration of calcium ion, the lower the concentration of fluoride ion, and vice versa. From this point of view, any factors that can affect the concentration of calcium ions in water may indirectly affect the concentration of fluoride ions. Calcium precipitating bacteria widely exist in natural environment, which can induce calcium carbonate precipitation. It is valuable to know how the calcium-precipitating bacteria distribute in high-fluorine groundwater, whether these bacteria can control the concentration of calcium ion by adjusting the precipitation kinetics of calcium carbonate and finally affect the content of fluoride ion, and whether inhibition of the activity of calcium-precipitating bacteria can increase the concentration of calcium ion and reduce the concentration of fluoride ion. A research work on these problems will help to reveal the formation mechanism of high fluorine water from a different perspective and is expected to provide a new choice for the treatment of high fluorine groundwater. This project plans to isolate different types of calcium precipitating bacteria from Xianghuangqi county of Inner Mongolia, a typical high fluoride area, and study the effect of calcium precipitating bacteria on the precipitation rate of calcium carbonate under varying concentration of carbon source to understand the nature of bacterial induced calcium precipitating under nutrient poor condition, and reveal the effect of calcium precipitating bacteria on the precipitation and dissolution equilibrium of fluoride ion. Finally, a survey would be conducted to assess the temporal and special variation of hydrochemistry index, microbial community structural and abundance of calcium precipitation bacteria in groundwater of this area. Based on these results the role of calcium precipitating bacteria in the formation of high fluoride groundwater will be evaluated.