东平湖可溶性有机物的荧光特征及环境意义

Fluorescence Features of Chromophoric Dissolved Organic Matter in Dongping Lake and Their Environmental Significance

东平湖作为南水北调东线工程最后一级调水湖泊以及山东省西水东送的水源地,其水质状况对受水区的用水安全起决定性作用。基于2013年8月的东平湖采样,对各水质参数分析发现,东平湖目前仍处于中富—富营养化水平,水质总体接近GB 3838—2002《地表水环境质量标准》IV类水质标准,仍不能满足调水要求,各水质参数表现出强烈的外源性。利用三维荧光光谱(EEMs)并结合平行因子分析法(PARAFAC)解析东平湖有色可溶性有机物的荧光特征,并探讨了荧光组分对东平湖环境污染指示意义的可行性。利用平行因子分析法(PARAFAC)共识别出2类4个荧光组分,分别是类腐殖质荧光组分C1(<225/305,386 nm)、C3(260,432 nm)和类蛋白荧光组分C2(240,360 nm)、C4(<225/275,304 nm)。相关性分析发现,陆源类腐殖质荧光组分C1与间接反映有机污染程度的溶解性有机碳(DOC)和化学耗氧量(COD)具有显著相关性,类蛋白荧光组分C2与总氮具有显著正相关性,可以对东平湖富营养变化情况进行快速、长期的监测。

The Dongping Lake holds a crucial position as the last water-staging lake of the east line of the Project of “ Diverting Water from South to North” of the country and the water source of the project diverting water from west to east in Shandong Province. Its water quality is directly related to water safety of the beneficiaries of the water diversion project. The water in the lake was sampled for analysis in August 2013 and all the water quality parameters indicate that the Lake was moderately or highly eutrophied and its water on the whole was close to Grade IV in quality set in the “Standard for Quality of Surface Water Environment” of the country and failed to meet the requirement of the water diversion project. All the water quality parameters show strong extraneousness. Fluorescent features of the chromophoric dissolved organic matters in the water were analyzed with EEMS and PARAFAC, and feasibility of using fluorescent components of the organic matters as indicators of environment pollution of the lake. PARAFAC analysis detected two classes and four types of fluorescent components, that is, C1 and C3 of the class of humic-like fluorescent components at 〈225/305,386 nm and 260,432 nm, respectively, and C2 and C4 of the class of protein-like fluorescent components at 240,360 nm and 〈225/275,304 nm, respectively. Terrigenous humic-like fluorescent component C1 was significantly related to DOC and COD, which may indirectly reflect degree of the organic pollution of the water, while protein-like fluorescent component C2 was significantly and positively related to TN. Therefore, the two components, C1 and C2 can be used as indicators for rapid determination and long-term monitoring of water eutrophication in the Dongping Lake.