【摘要】 溶解性有机质(Dissolved organic matter,DOM)普遍存在于土壤、沉积物和水体中,在环境地球化学和全球碳循环中发挥重要作用。消落带独特的"干湿交替"使土壤有不同的季节特征,但有关不同季节土壤DOM的性质、组成及来源差异还未见报道。利用紫外-可见光谱、三维荧光光谱(Excitation-emission matrices,EEMs)与平行因子分析模型(Parallel factor analysis,PARAFAC)相结合的方法,分析了丹江口库区消落带表层土壤DOM在不同季节的组成、结构,并对其来源进行解析。结果表明,不同季节消落带土壤DOM的组成特征存在一定差异。冬季土壤的有色溶解性有机物(Chromophoric dissolved organic matter,CDOM)浓度、土壤DOM的芳香性、缩合度、腐殖化程度、所含疏水性组分都高于夏季土壤,但参与光漂白的活性要低于夏季土壤。荧光指数(FI)、腐殖化指数(HIX)和生物源指数(BIX)表明该区土壤DOM的来源在不同季节都有明显的自生源特征,且腐殖化程度和生物可利用性都不高,并未表现显著差异。该区土壤DOM存在两个主要的荧光峰:紫外光区类富里酸峰、可见光区类富里酸峰和类腐殖酸峰。研究提出消落带淹水期间产生的DOM对水环境有很大影响,以内源为主的库区在水质改善的过程中需加强对内源物质的管控。这些研究结果可为消落带的水体修复和污染物的迁移转化提供科学依据。更多还原

【Abstract】 Dissolved organic matter(DOM) is a very important component in terrestrial and aquatic ecosystem, which also plays a key role in geo-environmental chemistry. Soil from water-level fluctuation zones have an important effect on water quality. But there was little qualitative analysis of DOM in soils in different season. In this study, DOM samples were extracted from soils obtained from typical water-level fluctuation zones of Danjiangkou reservoir. Ultraviolet-visible(UV-Vis) absorption spectra and the three-dimensional fluorescence spectrum(EEMs) combined with Parallel factor analysis(PARAFAC) were applied to determine the properties of DOM and its sources in different season. The results showed that the properties of DOM in different season had different changes, and the CDOM concentration, aromaticity, humification and hydrophobicity were much higher in winter than those in summer, but the photo-bleaching was lower. Moreover, the parameters of fluorescence index, humification index and biological index showed the existence of DOM in Danjiangkou reservoir was mainly derived from endogenous sources, which was closely correlated with biological or bacterial activity. Meanwhile, DOM from the Danjiangkou reservoir could be divided into two components: fulvic acid and humic acid. The results suggest that DOM releases during flooding for water-level fluctuation zones should be a crucial source of DOM in waters. The endogenous reservoir should strengthen the control of endogenous substances to improve water quality. The study could provide a theoretical basis for water remediation and the migration and transformation of contaminants in water-level fluctuation zones.更多还原