Study Of Characteristics Of Dom In Urban Runoff And The Mechanism With Typical Heavy Metal

The pollution of surface runoff has become an important part of urban non-point source pollution.With rapid development of urbanization,natural underlying surface has been replaced by impervious material,the sharp increasement of cars as well as the production and living of human beings,results in surface runoff polluted by a lot of organic pollutants,heavy metals,etc.The dissolved organic matter?DOM?is the main component of organic pollutants.Due to a large amount of unsaturated structure,functional group in DOM,including hydroxyl,carboxyl,carbonyl,amino and so on,these structure tends to ocCu²⁺r complexing reaction with heavy metals in runoff,altering the existing 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,with typical trend of more DOC,TP,turbidity,less ammonia nitrogen in winter than summer,the value of pH appears neutral,alkalescence in winter and summer,respectively.Qualitative characterization of surface runoff by using uv-visible spectroscopy,three-dimensional fluorescence spectroscopy,the results show that the green space is proportional to the content of humus in both winter and summer;terrestrial sources is in the leading position in the DOM in winter,however,summer is given priority to a mixture of terrestrial and microbial source.Four components was decomposed by PARAFAC in both winter and summer,including one kind of protein,three kinds of humus.The paper study the different components of DOM in runoff from summer and combination mechanism with heavy metal Cu²⁺,Pb²⁺,Zn 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⁺,Zn decreases successively,and the asynchronous spectrum illustrate that Cu²⁺,Pb²⁺ will react with the protein –like spectral band between 270-300 nm firstly,Zn will prior to react with the humus spectral band near 330 nm.