太湖秋季入湖水源中DOM的光谱学特征及通量

Various Inflows to Taihu Lake in Autumn:Spectroscopy Characteristics and DOM Flux

秋季是太湖水体DOM含量较高的季节。运用三维荧光光谱和紫外-可见光谱等手段分析了秋季太湖周边不同入湖水源（河水、雨水、污水处理厂水、直排生活污水）中DOM的组成和来源,及对太湖DOM的影响。结果表明：不同入湖水源中DOM的光谱学特征有显著差异。其中污水处理厂进水的ρ（TOC）为（68.5±13.9）mg/L,显著高于其它类型水;而且处理前污水〔ρ（TOC）为（68.5±13.9）mg/L〕、处理后污水〔ρ（TOC）为（21.7±5.15）mg/L〕、直排生活污水〔ρ（TOC）为（25.1±9.74）mg/L〕、河水〔ρ（TOC）为（27.3±1.27）mg/L〕和北太湖湖水〔ρ（TOC）为（27.9±2.35）mg/L〕中DOM浓度高、结构复杂,且均以腐殖质为主,同时类蛋白物质含量也较高;而雨水中的DOM以类富里酸物质为主,且其DOM的f450/500（荧光指数）平均值为1.61,呈现出外源特征,但其DOM结构相对简单。东太湖湖水DOM的f450/500值在1.73~1.92之间,表明其DOM主要为内源生物降解,显示出草型湖区与北太湖藻型湖区DOM组成和来源的显著差异。不同入湖外源DOM相对太湖水体总DOM的贡献为：河水〉雨水〉污水处理厂出水〉直排生活污水。其中河水DOM年入湖总量大（2.42×108kg）且成分复杂,对太湖湖水DOM的组成和含量影响最显著。

It has been noted that higher concentrations of DOM（dissolved organic matter）in Taihu Lake appeared in autumn than usual,so surveys were conducted in this season with respect to the inflow water into the Lake including river water,rainwater,STPs＇（sewage treatment plants）influents/effluents and sewages directly discharged into the Lake,with instruments of three-dimensional fluorescence spectroscopy and UV-visible spectroscopy analyzing DOM components and the relative parameters,tracing their sources and evaluating their impacts on DOM in the lake water. The survey suggested that DOM characteristics of varied water sources differed remarkably in spectroscopy-- concentration of ρ（TOC）（（68.5±13.9）mg/L）of STPs＇ influent（untreated sewage）was significantly higher than other types of water. Furthermore,lake-water in the north part of the Lake（ρ（TOC）=（27.9±2.35）mg/L）had complicated compositions,dominated by humus matters and high level of protein substance. On the other hand,average value of f450/500 of DOM of rainwater was 1.61,indicating the exogenous feature of high fulvic-like substances with relatively simple components and structure;and the value of f450/500 of DOM in the east part of the Lake was within the range from 1.73 to 1.92,showing an origin of endogenous biological degradation,also indicating the essential difference between the phyto-typed lake and algal typed lake in terms of source and composition of DOM. Regardingthe contribution of external sources from different inflows to the DOM in Taihu Lake,the ranking was river water rainwater STPs＇ effluents directly discharged domestic sewage;river water carried the most DOM（2.42×108 kg/a）into the Lake with complicated compositions,impacting water quality in terms of DOM the most of the external sources.