天津市典型排污河水体中溶解性有机质的荧光分布特征分析

利用三维荧光光谱研究了天津市两条典型排污河(大沽排污河和北塘排污河)沿河水体中溶解性有机质(DOM)的荧光分布特征,并通过对荧光参数——紫外区类富里酸峰中心位置的荧光强度与可见区类富里酸峰中心位置的荧光强度比值(r(A,C))和激发光波长370nm时荧光发射光谱强度在450nm与500nm处的比值(f450/500)的分析,探讨了水体中DOM的来源.结果表明,大沽排污河除中游个别位置外,其它位置水体均能检出紫外区类富里酸、类蛋白、可见光区类腐殖质、紫外区类腐殖质,总体上呈中游少、上下游多的特点;而北塘排污河水体中DOM的荧光峰从上游到下游呈增多趋势,但检出数量比较少.两条排污河水体中DOM均以紫外区类腐殖质最强.两条排污河水体中DOM的荧光强度与其水质参数之间存在显著相关性,而大沽排污河的相关系数更大.结合荧光参数r(A,C)和f450/500的分析和现场对入河排污口的调研,发现两条排污河的溶解性有机质来源均以入河排污口排污汇入(陆源)为主,另外还有少量沉积物有机质释放(微生物作用).

Analysis of the fluorescence distribution characteristics of dissolved organic matter in water of two typical drainage rivers in Tianjin

The fluorescent distribution characteristics of dissolved organic matter (DOM) in water of two typical drainage rivers (Dagu and Beitang Drainage Rivers) in Tianjin were analyzed by using three-dimensional fluorescence spectrometry. The sources of DOM were explored through examining the fluorescence parameters, which included the ratio of the fluorescence intensity at the fulvic acid-like peak center in ultraviolet (UV) region to that in visible (Vis) region (i.e., r_(A,C)) and the ratio of the fluorescence emission spectral intensity at 450 nm to that at 500 nm when the excitation wavelength was 370 nm (i.e. f_450/500). The fulvic acid in UV region, protein-like substance, and humus-like substance in both Vis and UV regions could be detected along the entire Dagu Drainage River except at some midstream points. In general, these detected substances were present more in the upstream and downstream than the midstream. In contrast, these characteristic peaks of DOM in Beitang Drainage River increased from upstream to downstream, but were less than those in Dagu Drainage River. The humic-like substance in UV region contributed most to the DOM in the two drainage rivers. Certain correlation was observed between the fluorescence intensity of DOM and the water quality parameters of the two rivers, while Dagu Drainage River exhibited a relatively higher correlation. Combining the analysis of r_{(A, C)} and f_450/500 with the onsite survey on drain outlets along the two rivers, it was found that the DOM in water of the two rivers mainly came from the drain outlets (i.e. land source). Besides, the organic matter released from the river sediments through microbial action also made a certain contribution to the DOM.