紫外线照射对高原湖泊富里酸-重金属相互作用的影响机制

With the development of urbanization and industrialization, a large number of heavy metals and organic pollutants were discharged into lakes. These pollutants interact strongly with natural organic matter. Due to its solubility, fulvic acid is strongly mobile and thus has signifiant effect on heavy metal transport and transformation. Fulvic acid is the key environmental factor controlling heavy metal pollution, and the the interaction between heavy metals and fulvic acid is controlled by the fulvic acid chemical properties. But fulvic acid property may be significantly altered under UV-light irradiation, which consequently change the interactions between heavy metal and fulvic acid. Two kinds of fulvic acid will be used as materials in the research. One fulvic acid will be extracted from the sediment in Dianchi Lake. Another will be extracted from Dianchi Lake water. Suwannee River fulvic acid(SRFA) from International Humic Substances Society (IHSS) will also be studied for compare in the research. The fulvic acid photodegradation under different UV-light strength will be simulated in UV Photolysis reactor. The environmental conditions such as fulvic concentration, dissolved oxygen, ionic strength and heavy metal ion will be altered, and the change of chemical structure, composition and functional groups will be detected for getting the important influence factors on fulvic acid photolysis under UV-light irradiation. By anlyzing free heavy metal ion concentration before and after fulvic acid photolysis, the complexing equilibrium constant and complexing capacity about fulvic acid complexing with heavy metals will be calculated for getting the rules of heavy metals transformation under fulvic acid UV photolysis. Simultaneously ,the heavy metal ions have effect on fulvic acid photolysis, and the mechanism of heavy metals promoting the fulvic acid photolysis will be probed. The research is benefit to understanding the mechanism of degradation of natural organic matters pollutants in natural water, and it is important to explore pollution water remediation mechanism and develop the pollution water repair techniques.It provides a basis law for the effective heavy metal ions treatment. The fulvic interactions with heavy metals under UV-light irradiation will be mastered in order to provide with the law for preventing heavy metal pollution in lake. The results will also be benificial to water environmental pollutants migration and transformation theoretics.

富里酸是控制重金属在水体中的迁移转化重要的环境介质之一, 其与重金属的相互作用受控于富里酸的化学性质. 高原湖泊在紫外线的强烈照射下, 引起富里酸性质的变化，可能成为重金属和富里酸相互作用中的重要动因. 本研究拟从滇池沉积物和水体中提取富里酸, 将其和Suwannee River富里酸对比, 模拟其在不同紫外线强度下光解过程, 分析光解前后富里酸的化学结构、成分和官能团的变化, 获得紫外线照射富里酸光解的重要影响因素, 考察光解前后重金属与富里酸的络合平衡常数和络合容量的变化, 研究富里酸光解对重金属迁移转化规律的影响, 探索重金属对富里酸光解反应的作用及机理. 本项目有助于深入了解天然有机质在自然水体中的降解机理, 为重金属离子的有效治理提供基础数据和规律, 对于探讨湖泊水体修复机理、发展修复技术也具有重要意义.

富里酸是水体重金属迁移的重要环境介质，研究从滇池沉积物和水体中提取富里酸，将其和标准富里酸（Suwannee River FA）对比，利用光解反应器研究滇池富里酸在不同紫外线强度下光解过程, 分析光解前后富里酸的化学结构、成分和官能团的变化, 以及光解前后重金属与富里酸的络合率的变化。课题研究了紫外线照射下富里酸官能团及分子结构变化规律，在紫外线照射下，滇池富里酸分子碎片化，含氧官能团增加，和标准富里酸相比，更易变成小分子有机物，光解影响因素pH值对其影响最大，在酸性条件下，富里酸光解速率较快；研究了紫外线照射前后富里酸与重金属络合平衡的变化，关注pH值、金属离子浓度、离子强度对光解后滇池富里酸与重金属络合率的影响;研究了光解前后官能团的变化以及对金属离子络合官能团变化规律，滇池富里酸发生光解，造成羟基和羧基等官能团的小分子官能团的化合物作为中间产物产生，增加重金属离子和滇池富里酸的络合量；研究了Fe、Pb、Cd三种金属离子共存时，光解后富里酸对Pb络合率最大，对Cd络合有抑制作用。综上所述，本项目研究了滇池富里酸光解以及光解前后对重金属离子络合的变化规律，为滇池重金属离子的有效治理提供基础数据和规律。项目资助发表论文2篇。培养硕士生5名，其中3名已经取得硕士学位，2名在读。项目投入经费49.0000万元，支出19.3038万元，剩余经费29.6962万元，剩余经费计划用于本项目研究后续支出。