溶解性有机质对水源地微囊藻毒素光敏降解机理及水力调控机制研究

Microcystin-LR (MC-LR) is a highly toxic carcinogenic substance, and seriously threat to drinking water safety. Traditional methods for removing MC-LR mainly depend on oxidation, adsorption and aquatic plants. These methods have disadvantages of small treating scale, and potential environmental risks of chemical drug. This subject is aimed at exploring a new MC-LR situ purifying method in drinking water sources on the basis of reservoir ecological operation theory and the principle of photodegradation. The main idea is to optimize the content and composition of dissolved organic matter (DOM) through use of reservoir ecological operation in drinking water sources, and then promote the photodegradation of MC-LR under natural condition. The contents of this research are shown as follows: extract multicomponent DOM and carry out MC-LR photodegradation experiment under multicomponent DOM to clarify the effect mechanism of multicomponent DOM on the photodegradation of MC-LR; Structure the quantitative relationship between hydrological conditions and DOM content as well as composition, coupling multi-objective ecological scheduling model to reveal the change law of DOM content and composition under reservoir complete scheduling cycle, and then obtain the long term reservoir ecological operation scheme combining power generation, acquisition and drinking water safety, eventually achieve the MC-LR situ purification. This subject has an important significance for protecting drinking water safety.

天然水体中的微囊藻毒素LR（MC-LR）是高毒性的致癌物质，严重威胁饮用水安全。传统的去除MC-LR方法主要有药剂氧化、材料吸附和水生植物作用等，这些方法存在治理规模小、投加的药剂与材料有潜在环境风险等问题。本课题基于水库生态调度理论与光降解原理，探索利用水库生态调度来优化水中溶解性有机质（DOM）含量和组成，进而促进MC-LR光降解的水源地水体原位净化方法及净化机理。通过多种DOM组分的分类提取，多组分DOM影响下的MC-LR光降解实验，水文条件与DOM含量、组成之间定量关系分析，以及多目标生态调度模型构建，揭示水库完整调度周期内水体中DOM含量、组成的变化规律，阐明多组分DOM对MC-LR光降解的影响机理，并由此获取能够兼顾防洪、发电和水质安全的水库常态化生态调度方案，从而实现水源地MC-LR的原位消减。本课题对保障饮用水安全具有重要意义。

天然水体中的微囊藻毒素LR（MC-LR）是高毒性的致癌物质，严重威胁饮用水安全。传统的去除方法主要依靠氧化、吸附以及水生植物等对MC-LR进行去除，这些方法存在成本大、治理规模小、投加的化学药剂有潜在环境风险等问题。本课题利用超滤法对溶解性有机质（DOM）进行分子量分级，结合三维荧光光谱和傅立叶变换红外光谱进行分析，并以分级后的DOM作为光敏剂，通过室内实验对MC-LR进行光敏降解。结果发现，经光屏蔽效应校正后，太阳光照射下不同级分DOM均表现为促进MC-LR的光解，MC-LR在10小时内的去除率均超过50%。DOM光照下产生的两种主要活性氧物种（1O2，•OH）对MC-LR的降解贡献表明，DOM促进污染物光解的主要机制为活性氧物种引发的自由基氧化反应。FT-ICR-MS检测结果发现DOM中类木质素所占比例随其分子量的降低而降低，类木质素比例越低，MC-LR的降解效果越好，这说明小分子量DOM比例高更有利于MC-LR降解。在野外采样的基础上，利用三维荧光结合平行因子分析法对山仔水库中DOM进行分析，结果发现山仔水库DOM组分主要为小分子的类蛋白物质和较大分子的富里酸。相比于枯水期，浮游植物代谢率在丰水期的防洪调度工况下较高，其代谢产物对DOM的组成和分布有较大的贡献。综合光降解实验和DOM采样分析结果，DOM中类蛋白和富里酸的比例为6.5:3.5时为最佳，即更有利于MC-LR光降解。利用Landsat8遥感影像对山仔水库DOM含量进行反演并结合非线性回归分析及DOM最佳组分比例计算出山仔水库最小生态径流量为84.7m3/s。在此基础上构建了促进MC-LR降解的水库生态调度模型并通过蜘蛛改进优化算法计算出山仔水库的生态调度方案为9月份生态补水48.5m3/s。本课题对水源地水质保障和生态调度具有重要指导意义。