Composition And Spectroscopy Characteristi-cs Of Molecular Weight Fractions Of Dissolved Organic Matters In The Sediment From Taihu Lake, China

This paper mainly studies the distribution of molecular features in differentdepth and different particle size of DOM in the sediments from Taihu Lake, and analyses DOMusing three-dimensional fluorescence spectra and UV-visible Spectra methods, combined withcomponents and sources of DOM from various water sources (River water, Rainwater, Wastewaterfrom sewage treatment plant and directly discharged domestic sewage) to Taihu Lake and theirimpacts on DOM of Taihu Lake water. The results show that: Taihu sediment is mainly loose statesediment grain size finer, north Taihu and east Taihu sediment particle size composition is roughlythe same, with silt and very fine sand. However, a higher ratio of east Taihu clay sediments, mainlysilt and very fine sand and silt. It is account for43.27%-70.99%of the total deposits, and very finesand with the ratio of12.48%-19.21%. This shows that east Taihu Lake is mainly composed of fineparticle diameter of soil composition, also shows that the east Taihu Lake was relatively northTaihu is more delicate.There were remarkable differences in spectroscopy characteristics of DOM among various watersources and it was indicated that remarkable differences also existed in the DOM composition ofdifferent water sources to Taihu Lake. Where the drainage dispose factory effluent, forthrightevacuated domestic sewage, river and north of Taihu lake DOM concentration is high, complexstructure, and humus are based, while the class content of protein substancesis higher. The DOM ofrainwater, indicating exogenous features with fulvic-like substances, but with relatively simplecomposite structure. The east Taihu Lake, indicating that the DOM mainly derived fromendogenous biological degradation. It indicated the essential difference in the source andcomposition of DOM between the grass type lake and algal type lake. Comparison of differentsources into Taihu lake DOM and found that the water capacity of all kinds into Taihu Lake in theDOM contribution order: river> rain> directly discharged domestic sewage> sewage treatmentplant effluent.These exogenous large quantity of lotion into the lake and the DOM structure is complex, has a significant influence on the composition and content of Taihu lake DOM.Different molecular size order of different depth of DOM in the sediments of north Taihu:(molecular weight <=500Da)>(molecular weight>5000Da)>(500Da <molecular weight <=2000Da)>(2000Da <molecular weight <=3500Da)>(3500Da <molecular weight <=5000Da); different the molecular weight of different depth of the order of east Taihu sediments DOM:(molecular weight <=500Da)>(500Da <molecular weight <=2000Da)>(2000Da <molecularweight <=3500Da)>(molecular weight>5000Da)>(3500Da <molecular weight <=5000Da).East Taihu Lake in0.063mm,0.125mm,0.25mm and0.5mm in four different size fractions ofsediments DOM different molecular size order as:(molecular weight <=500Da)>(molecularweight>5000Da)>(500Da <molecular weight <=2000Da)>(3500Da <molecular weight <=5000Da)>(2000Da <molecular weight <=3500Da). East Taihu different particle sizedistribution of molecular weight DOM sediments vary greatly. Mainly for the amount of DOM(molecular weight <=500Da) and high molecular weight (molecular weight>5000Da) accountfor the largest proportion; but the molecular range of intermediate quantity (500Da <molecularweight <=2000Da),(2000Da <molecular weight <=3500Da) and (3500Da <molecular weight<=5000Da) accounts for only a small.Taihu different molecular weight components of DOM in sediment samples have fourfluorescence peaks. But the position and strength of fluorescent light peaks of different elememtqualities of three-dimensional fluorescence spectra were different. North and east Taihu Lake insurface sediments DOM content of humic matters are high elememt quality components are multiand complex, comprising humic matters transitional nature, the whole north Taihu fluorescent lightpeak strength to be bigger. East Taihu Lake is relatively simple protein-based substances, humicmatters less content, type of grass belonging to East Taihu Lake, DOM and more from thedegradation of plant; at the same time that compared with the north Taihu, east Taihu Lake frompollution interference is less, the water quality is relatively good. The molecular weight≤500Dacomponents of east Taihu (36-42cm) in the sediments at the bottom of the DOM complexcomponent, content rich, heavily polluted. From0.063,0.125,0.25and0.5mm in four differentelememt quality components, the more the underlying sediments, east Taihu sediments of thematerial composition in the DOM is more complex and serious contamination.Popularly the trend of DOM different depths of sediments in Taihu Lake two typical lakedistricts, A253/A203, SUVA254, A250/A350, E250/E365and ABS285five UV characteristicparameter numerial numbers have a consistent trend in the0-12cm with increasing depth is anincreasing trend, which diminishes with increasing depth of12-45cm trends in this area. In generalterms, the numerial numbers of A253/A203and SUVA254in DOM of east Taihu sediments different molecular sizes are small, and the numerial numbers of A250/A350, E250/E365andABS285to be relatively higher.