夏季巢湖入湖河流溶解性有机质来源及其空间变化

Sources and Spatial Variation of Dissolved Organic Matter in Summer Water of Inflow Rivers Along Chaohu Lake Watershed

使用紫外-可见光吸收光谱(UV-vis)和三维荧光光谱-平行因子分析法(EEM-PARAFAC),分析了2019年夏季巢湖流域丰乐河、杭埠河、岐阳河、兆河和南淝河水体溶解性有机质(dissolved organic matter,DOM)的来源及其空间变化.结果表明,南淝河DOM吸收特征参数SUVA254显著低于其它河流,而光谱斜率比SR显著高于杭埠河,表明城市污染物径流排入降低了南淝河水体DOM的芳香性,但对其分子量影响较低.南淝河DOM荧光指数(FI)和生物源指数(BIX)大于其它河流,而腐殖化指数(HIX)低于其它河流,指示其DOM自生源高于其它河流.使用EEM-PARAFAC从河流DOM中提取出4种类腐殖质组分(C1~C4)和2种内源类蛋白荧光组分(C5、C6),其中,类腐殖质组分包括陆源有机质(C1、C3和C4)和微生物降解产物(C2).沿河流方向,5条河流河水溶解性有机碳(dissolved organic carbon,DOC)、a(355)和DOM荧光组分呈不同的空间变化特征,其中丰乐河、杭埠河、岐阳河和兆河DOM受农田土壤径流输入影响明显,而南淝河DOM主要受城市污染物径流和污水处理厂出水影响.

The sources and spatial variations of dissolved organic matter(DOM) in summer water of inflow rivers(FL,HB,QY,ZH,and NF) along the Chaohu Lake watershed were analyzed using the ultraviolet-visible absorption spectrum(UV-vis) method and threedimensional excitation emission matrix fluorescence spectroscopy-parallel factor analysis(EEM-PARAFAC).The specific ultraviolet absorbance of DOM at 254 nm in the NF river was lower than in other rivers,and the spectral slope ratio(SR) of the NF river was higher than that of the HB river.This showed that the urban runoff inputs reduce the aromaticity of DOM in the NF river water,but has little effect on the molecular weight.The high fluorescence index(FI) and biological index,and the low humification index,indicated the main autochthonous sources of the DOM in the NF river.Four humic-like components(C1-C4),comprising terrestrial organic matter(C1,C3,and C4) and microbial degradation products(C2),and two protein-like components(C5 and C6) were identified as the main sources of DOM in the inflow rivers along the Chaohu Lake watershed.The dissolved organic carbon and DOM fluorescence components in the river water exhibited spatial variation along the direction of flow.The DOM in water from FL,HB,QY,and ZH was sourced from soil runoff inputs,whereas in NF water,it was mainly sourced from urban runoff and wastewater treatment plant effluents.