鄱阳湖有色可溶性有机物的光学特性、时空分布及其来源解析

Chromophoric dissolved organic matter (CDOM) was an important part of dissolved organic matter and plays an important role in biogeochemical cycle of bioactive elements in waters, which have indicating significance for water quality and the evolution and development of ecological environment. This program used Poyang Lake with high water level fluctuation as the research object, using ultraviolet--visible spectra, three dimensional excitation-emission matrix fluorescence spectroscopy and parallel factor analysis (PARAFAC) to characterize the optical properties of CDOM and their distributions during the dry season, rising season, flood season and retreating season in Poyang Lake, and to explore the effect of hydrological regime on CDOM. Through studying the concentrations and optical properties of CDOM in rivers and rainfall into lakes, and combining the experiments including the degradation of the dominant species of wetland plant and aquatic plant in Poyang Lake, and the releasing process of typical sediments, the optical properties of extraneous and endogenous CDOM in Poyang Lake were obtained to clarify the source mechanism of CDOM in Poyang Lake. This program would clarify the distribution of CDOM in Poyang Lake, and reveal the characteristics and contribution of the extraneous inputs and endogenous release of CDOM in Poyang Lake, which have guiding significance for tracking the source and transportation behavior of dissolved organic matter, and could provide the theoretical basis for the solvement of water environmental issues in Poyang Lake.

有色可溶性有机物（CDOM）是溶解性有机物库的重要组分，参与湖泊水体生物地球化学循环的关键环节，对湖泊的水质与水生态环境的演化发展具有重大意义。本研究以典型高水位变幅的通江湖泊--鄱阳湖为研究对象，拟采用紫外--可见光谱、三维荧光光谱结合平行因子分析技术，探明枯水期、涨水期、丰水和退水期水体中CDOM的光谱吸收和荧光特性，揭示不同水情条件下CDOM浓度及其荧光组成的分布特征，探究水文情势对CDOM的影响；通过研究五大入湖河流和大气降水输入CDOM的光学特性，探明外源CDOM的贡献；结合野外调查与室内模拟实验，弄清湿生植物和水生植物降解、典型沉积物释放CDOM的过程及其光学特性，明确内源CDOM的贡献。本项目研究将明确高水位变幅鄱阳湖CDOM的时空分布规律，外源输入和内源释放CDOM的特性及其贡献，揭示溶解性有机物的来源及迁移变化规律，为解决鄱阳湖的水生态环境问题采取针对性措施提供理论指导。

本研究以典型高水位变幅的通江湖泊--鄱阳湖为研究对象，采用紫外--可见光谱、三维荧光光谱结合平行因子分析技术，探明枯水期、涨水期、丰水和退水期水体中CDOM的光谱吸收和荧光特性，揭示了不同水情条件下CDOM浓度及其荧光组成的分布特征。研究发现，CDOM的季节变化和时空分布受水文节律的影响有所差异。涨水期和丰水期鄱阳湖含有大量具有高比例类腐殖质物质的CDOM物质，类腐殖质和类酪氨酸物质在两个极端水文条件下表现出截然不同规律。在丰水期时CDOM空间异质性较高，湿地附近水域出现大量具有低芳香性CDOM物质。通过研究外源（包括五大入湖河流、降雨输入）CDOM的光学特性，以及内源（包括植物、沉积物）室内模拟实验释放CDOM的光学特征，将各来源纳入分析端元，鄱阳湖水体作为混合端元，针对不同水文节律筛选指示来源特征的敏感光学参数，应用端元混合法分析量化各来源端元的相对贡献。结果表明，外源输入的相对贡献要大于内源，其中入湖河流在涨水和丰水期的相对贡献较大，从而进一步验证了在涨水期，鄱阳湖CDOM分布主要受入湖河流的影响。研究基于CDOM光学参数揭示并量化了典型水文节律下溶解性有机物各来源的相对贡献，明晰了鄱阳湖CDOM的主要来源，有助于后期解决鄱阳湖水生态环境问题采取针对性措施。