平寨水库荧光溶解性有机质的来源、特征及其动态转化

利用三维激发发射矩阵光谱(3-D EEM)和平行因子分析,研究了三岔河流域平寨水库溶解有机质的来源、组成和转化情况。在平寨水库的入库水、表层水(0～5 m)、深层水(10～60 m)和出库水中,检测到了几种荧光溶解有机质组分,分别为陆源类腐殖质、自源类腐殖质和浮游植物源的类蛋白质(或类色氨酸或类酪氨酸)。陆源类腐殖质的荧光强度在入库水中略高于出库水,表明陆源类腐殖质在水库系统中相对稳定,大坝截流对其影响不大。自源类腐殖质的荧光强度在库区明显高于入库水和出库水,表明自源类腐殖质既由自源有机物分解产生,又在光化学、微生物和大坝物理拦截过程的影响下发生分解;其他荧光组分中也检测到相似的结果。水温、pH、溶解氧和有色溶解有机质表现出相似的季节变化,光化学和微生物以及大坝拦截是引起水库入库水、库区表层水、库区深层水和出库水中荧光溶解有机质时空动态变化的主要原因。

Sources, Characteristics and Transformation of Fluorescent Dissolved Organic Matter in the Pingzhai Reservoir

This study investigated sources, characteristics and transformation of dissolved organic matter (DOM) in the Pingzhai Reservoir along the Sancha River Basin, SW China, by using fluorescence properties of three-dimensional excitation emission matrix (3-D EEM) spectroscopy and parallel factor (PARAFAC) analysis. The results demonstrated that several fluorescent DOM (FDOM) components were identified in waters of incoming, surface layer (0-5 m), deeper layer (10-60 m) and outgoing of the Pingzhai reservoir and they could be denoted as terrestrial humic-like substances, autochthonous humic-like substances, protein-like substances, tryptophan-like substances, tyrosine-like substances. The fluorescence intensity of terrestrial humic-like substances in outgoing waters decreased slightly in comparison with that in incoming waters, suggesting that the terrestrial humic-like substances are relatively recalcitrant to degradation during the transportation from inflowing to reservoir and then outgoing water. Conversely, the fluorescence intensity of the autochthonous humic-like substances was higher in the reservoir than in the incoming and outgoing waters, suggesting that the autochthonous humic-like substances are simultaneously produced from autochthonous organic matter and then degraded under influences of photochemical, microbial and dam-barrier physical processes. Similar results were also observed for other fluorescent substances. Temperature, pH, DO and CDOM showed the similarseasonal change. These results suggest that the influences of photochemical and microbial processes along with dam-barrier physical processes are responsible for space-time transformation dynamics of FDOM components in the incoming, reservoir area surface water, reservoir area deeper water and outgoing waters of the Pingzhai reservoir.