Dissolved Organic Matter In Natural Aquatic Environments And Its Complexation With Cu²⁺ A Study Based On Fluorescence Spectroscopy

Dissolved organic matter (DOM), which is ubiquitous in almost all of the naturalwaters(eg. sea and ocean, river, lake, bog water and groud water), was widely studiedbecause of its significant role in shaping the aquatic environments since last decade. DOMinfluences a wide variety physical, chemical and biological processe. Light absorption byDOM has a strong influence on the penetration of ultraviolet and photosyncheticallyactive radiation. DOM mainly comprises organic acids and, therefore, affects pH of thewaters and in some acidic waters acts as a buffer. The interactions between DOM andbioavilabity. DOM acts as a large organic carbon reservoir exchanging with theatmosphere, where carbon (as CO2) plays as important role in climate regulation. All ofthese provide very good reasons for acquiring a better understanding of the origin,composition and structure features of DOM and the role it plays in geochemical processes.The essay chose the above front-edge topic. The Grand East Lake WaterSystem(GELWS) has been studied, which consists of the largest fresh lake and thesurrounding five lakes in Wuhan, namely the consists of East Lake, Yanxi Lake, YandongLake, North Lake, Yangchun Lake and Sha Lake. Three-dimensional excitationemissionmatrix fluorescence spectroscopy, UV-vis and fluorescence quenching titrationhave been applied to this research as analysis methods, while the states of art technologies,PARAFAC and Ryan-Weber Mode as statistic analysis methods.The result suggests:1) The DOM in the East Lake consists mainly of protein-likepeak and folic-like peak, namely C1, C2and C3.2) East lake has the relative lowcontamination. The most contaminated part located at the intersection with Shuiguo Lake.Surrounding industrial sewage, domestic sewage and other human behavior conductedpollution (86.75%) are the major contamination. Natural metabolic pollution (13.25%) byphytoplankton and aquatic microorganisms is light.3) There is a linear correlationbetween the general fluorescence intensity of DOM in East Lake, C1, C2and UV-vis，totalnitrogen, total phosphorus. There is no such linear correlation with C3.4) The generalfluorescence intensity of DOM decreases as Cu ionic concentration increases. C1and C2have obvious decrease while C3gently decreases. The binding coefficient of C1 （tryptophan-like peak）and C2（tyrosine-like peak）is higher than of C3（folic-like peak）5) The binding coefficient of general DOM in Yangchun Lake and Cu ionic concentrationis the highest, suggesting that the lake has the most contamination. The higher theconcentration of DOM, the more active connection with Cu ionic concentration, the higherthe metal ion mobility, toxicity and biological availabity, the worst the damage. Thus, thecontamination degree decreases as: Yangchun Lake, Sha Lake, East Lake, Yanxi Lake,North Lake and Yangdong Lake.