不同浓度柠檬酸影响茶园土壤氟释放的动力学研究

营 浩; 张显晨; 郜红建; 宛晓春

文章摘要

营浩,张显晨,郜红建,宛晓春.不同浓度柠檬酸影响茶园土壤氟释放的动力学研究[J].农业环境科学学报,2014,33(7):1372-1378.

不同浓度柠檬酸影响茶园土壤氟释放的动力学研究

Kinetics of Fluoride Release from a Tea Garden Soil Under Different Concentrations of Citric Acid

DOI：10.11654/jaes.2014.07.017

中文关键词: 柠檬酸茶园土壤氟形态动力学

英文关键词: citric acid tea garden soil fluorine fractions kinetics

基金项目:

作者	单位
营浩	安徽农业大学资源与环境学院，合肥 230036
张显晨	安徽农业大学茶叶生物化学与生物技术教育部重点实验室，合肥 230036
郜红建	安徽农业大学资源与环境学院，合肥 230036；安徽农业大学茶叶生物化学与生物技术教育部重点实验室，合肥 230036
宛晓春	安徽农业大学茶叶生物化学与生物技术教育部重点实验室，合肥 230036

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中文摘要:

为阐明茶树高富集土壤氟的化学机制，采用动力学方法研究了茶树根系分泌柠檬酸对茶园土壤氟形态及其在土壤固-液相分配的影响。结果表明，土壤溶出液的pH和电导率随溶出时间的增加而逐渐减小。土壤氟的释放存在快速释放和慢速释放两个阶段，呈现初始（0~6 h）溶出浓度较高，而后（6~10 h）逐渐减缓的趋势。一级动力学方程、Elovich方程、扩散方程、双常数方程均对土壤氟的溶出过程有较好的拟合，决定系数（R2）均大于0.91。土壤溶出液中的游离态氟和总氟的释放量随柠檬酸浓度的升高而增加，反应开始前2 h的高浓度柠檬酸溶出液中Al-F络合物的浓度较大，反应开始前1 h的Al-F络合物主要以AlF3为主，占氟溶出总量的90%左右；随着溶出时间的延长，AlF+2的溶出量逐渐增大，并逐渐超过AlF3。高浓度柠檬酸促进土壤氟的溶出释放，有利于Al-F络合物向AlF2+、AlF+2 形态转化。

英文摘要:

Citric acid is one of organic acids excreted by tea plants. Here, the effects of citric acid on F forms and partition between solid and solution phases in a tea garden soil were investigated using a kinetic method. Soil solution pH and electric conductivity decreased with increasing reaction time. Release of F from the soil was quick at the beginning and then slowed down. Concentrations of F in soil solution were higher from 0 to 6 h than from 6 h to 10 h. Kinetic process of F release from tea garden soil fitted the first-order reaction kinetics and Elovich, diffusion and double constant equations as well, with all the coefficients of determination（R2） greater than 0.91. Amount of free F and total F in soil solution increased with increasing concentrations of citric acid. Amount of Al-F complexes released during the first two hours were greater under high than under low concentrations of citric acid. During the first 1 hour, AlF3 was the main form of Al-F complexes, accounting for 90% of the total F released from the tea garden soil. With increasing reaction time, however, amount of AlF+2 released from the tea garden soil increased and finally surpassed AlF3. High concentrations of citric acid promoted F release from the soil and facilitated the conversion of Al-F complexes into AlF2+ and AlF+2. These results provide insights into the chemistry of high F accumulation in tea tree plants from soils.

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