再生水DOM腐殖质电子穿梭效应对地下水中As释放影响机制研究

Aiming at the uncertainties of As release during the infiltration of reclaimed water DOM, the Beijing Chaobai River reclaimed water utilization area with high As background was selected. This study focus on the effect of electron shuttle of DOM humic substances (HS) on As release. The variation characteristics of groundwater DOM HS under the influence of reclaimed water were analyzed, and the relationship between the release pattern of As and the distribution of DOM HS was discussed. The separation and extraction of DOM HS from reclaimed water and different As content groundwater were carried out, and their electronic acceptance, supply, shuttle capacity and circulation ability were tested. Trying to develop the spectral indicator of electron shuttle capacity which would provide the basis for revealing the relationship between electron shuttle capacity and As release in the field conditions. The experiment of microbial culture of different content DOM HS electron shuttle effect is carried out to determine the influence of concentration effect on electron shuttle capacity. In-situ column simulation of the contribution of DOM HS electron shuttle effect to As release was conducted. Combined with field and simulation results, to explore the effects of different content and properties of reclaimed water DOM HS on electron shuttle and As release, and finally to figure out the main mechanism of action of As release contributed by electron shuttle effect.

针对河道再生水DOM入渗地下后对含水层As释放效应不清的现状，选择具有高As背景的北京潮白河再生水利用区，重点关注输入的DOM腐殖质电子穿梭效应对As释放的影响。分析再生水影响下地下水DOM腐殖质变化特征，探讨As的释放规律与DOM腐殖质分布变化关系；开展再生水及不同As含量DOM腐殖质的分离提取，测试其电子接受、供给、穿梭性能及其循环能力，探索建立电子穿梭能力的光谱指示指标，为揭示野外条件下电子穿梭能力与As释放关系提供基础；开展不同含量DOM腐殖质电子穿梭效应微生物培养实验，明确浓度效应对电子穿梭能力的影响，进行半原位条件下再生水DOM腐殖质入渗柱实验模拟研究，分析DOM腐殖质电子穿梭效应对As释放的贡献，结合野外与模拟实验结果，探讨不同含量与性质的再生水DOM腐殖质对电子穿梭及As释放的影响，揭示电子穿梭效应引起As释放的主要作用机制。

项目基于潮白河再生水利用区及周边等研究区域，开展了野外地表水有机质等组分入渗以及室内模拟条件下，地下水中As释放的演变规律研究，探究了地表有机质腐殖质等组分对地下水中As释放的影响。研究发现，野外再生水河道条件下，地表腐殖质等有机质组分对地下水中As的影响作用不显著，地下水中As的释放主要受控于含水层介质本身的氧化还原条件影响。分析主要受再生水河道回补区域含水层上赋粉质粘土等弱透水层结构，进而对地表有机质的入渗产生明显的阻滞效应。室内的模拟实验发现，外源有机质入渗影响下，含水层介质中的As发生显著释放，在添加腐殖质的实验组，As释放出现显著增加，腐殖质的电子转移效应在其中发挥了显著的作用，增强了微生物异化还原作用的电子传递效率。