径流雨水中溶解性有机质特征演化及其对典型污染物迁移和生物有效性的影响

地表径流污染已经逐渐成为城市面源污染的重要组成部分。其中溶解性有机质DOM (Dissolved organic matter)是有机污染物的主要组成部分。DOM中因为含有大量不饱和结构、官能团,其中包括羟基、羧基、羰基、胺基等,这些结构容易与径流中重金属结合发生络合反应,改变重金属的赋存形态,从而对其迁移转化及其生物有效性产生很大的影响。本文以北京市地表径流为研究对象,研究城市地表径流在冬、夏季不同功能区不同下垫面中溶解性有机质特征及其与典型重金属的作用机制,通过荧光淬灭滴定实验,研究夏季径流雨水中DOM的不同组分与重金属Cu~(2+)、Pb~(2+)、Zn~(2+)之间的结合机制。研究结果显示PARAFAC将获得的样品都分解成2类6个不同的组分,1种腐殖酸,1种类蛋白;类蛋白物质的荧光强度与Cu~(2+)、Pb~(2+)的淬灭率要强于腐殖酸,而Zn~(2+)则呈现相反趋势;通过使用二维相关同步光谱发现DOM对重金属Cu~(2+)、Pb~(2+)、Zn~(2+)的敏感性呈现递减趋势,二维相关异步光谱发现Cu~(2+)、Pb~(2+)会先与位于270—300nm附近类蛋白光谱带反应,Zn~(2+)则会先与330nm附近的腐殖酸光谱带反应。

Study of characteristics of DOM in urban runoff in Beijing and the mechanism with typical heavy metal

The pollution of surface runoff has become an important part of urban non-point source pollution. The dissolved organic matter (DOM) is the main component of organic pollutants. Because DOM contains a large number of unsaturated structures and functional groups, including hydroxyl, carboxyl, carbonyl, amine groups, etc., these structures are easy to complex with heavy metals in runoff, changing the form of heavy metals, affecting the migration and transformation and its bio-availability. Based on surface runoff as the research object in Beijing, this paper studies the characteristics of DOM in different underlying surface in different functional areas in winter as well as summer and its mechanism of complexing with heavy metals,study the different components of DOM in runoff from summer and combination mechanism with heavy metal Cu²⁺, Pb²⁺, Zn²⁺ by fluorescence quenching titration experiments. Research results show that PARAFAC will decompose the samples into 2 types and 6 different components, including one types of humus, one types of protein-like; The quenching rate of fluorescence intensity by Cu²⁺, Pb²⁺ and protein material is stronger than those with humus, while Zn is exactly opposite; Two-dimensional correlation synchronous spectrum reveal the facts that the sensitivity of DOM to heavy metal Cu²⁺, Pb²⁺, Zn²⁺ decreases successively, and the asynchronous spectrum illustrate that Cu²⁺,Pb²⁺ will react with the protein -like spectral band between 270-300nm firstly, Zn will prior to react with the humus spectral band near 330 nm.