黄河流域环境因素对河湖CDOM光学特性影响研究

The optical properties of chromophoric dissolved organic matter (CDOM) and the influences of environmental factors are crucial for the research of carbon cycle process and modeling bio-optical in the aquatic ecosystem. To date, the studies have been widely carried out on CDOM optical properties and the parameterization of remote sensing in inland water. Comparatively, there are less investigations about neither varieties of CDOM optical properties and components due to environmental variation on the basin scales nor CDOM characteristics in urban waters influenced by human activities. The Yellow River basin, water resources system of which is sensitive to environmental changes, is located in the arid and semiarid region with fragile ecological environment. Thus, this research based on the typical areas of the Yellow River basin, proposes to illuminate the temporal-spatial distribution characteristics of water CDOM in different geomorphologic elements with techniques of GIS, RS and environmental sciences. Meanwhile, the correlation between environmental factors and water CDOM optical properties in different sub-basins of study areas will be analyzed in order to determine the main factors acting on CDOM. Furthermore, optical properties, compositions and sources of CDOM in urban waters and transects of Yellow River passing typical cities will also be investigated in this research. The potential findings from the research could be beneficial for further understanding of varieties and transformation mechanism of CDOM optical properties from headstream to estuary of the Yellow River in aquatic ecosystems, providing data support for studying environmental influences on inland water comprehensively and offering important reference for development and perfect of the bio-optical models.

水体CDOM光学特性及环境因素影响研究，对水生态系统碳循环过程以及生物光学模型构建具有至关重要的作用。虽然有关内陆水体CDOM的光学性质及其遥感参数化研究都已大量开展，但对于流域尺度上环境变化引起的CDOM光学特性及其组分变化、受人类活动影响较大的城市水体CDOM特征的认知不够深入。黄河流域地处干旱、半干旱区，生态环境脆弱，水资源系统对环境变化十分敏感。因此，本研究立足于黄河流域典型区，结合GIS、RS及环境理论和方法，分析黄河流域典型区水环境CDOM的生物光学特性，拟明确河湖CDOM的光学特性分布特征，确定流域尺度上环境要素对CDOM的影响作用，分析黄河流经的典型城市的断面及城市内部水体CDOM的光学特征、组成与来源。本研究将有利于深入理解黄河从发源到入海的水生态系统CDOM的光学特性的变化及转化过程，为研究环境影响对内陆水体的作用提供数据支持，也为生物光学模型的发展和完善提供重要借鉴。

本项目在充分了解国内外有关CDOM光学特性研究的基础上，以黄河流域河湖水体为研究对象，以对CDOM光学特征的研究为主线，对内陆水体的CDOM吸收和荧光特征的时空分布、主要组成及来源以及流域内环境影响因素对CDOM的影响进行分析讨论，为研究环境影响对内陆水体的作用提供数据支持，也为生物光学模型的发展和完善提供重要借鉴。通过研究发现，（1）黄河流域河湖水体CDOM的光学特性空间特征明显，各典型子流域水体CDOM光学特性差异较大。湖泊CDOM的吸收和荧光强度明显高于河流。伊洛河CDOM在390 nm处出现吸收峰，与其他水体差别较大。（2）黄河流域河湖水体CDOM的组成和来源存在显著差异。湖泊CDOM的分子量明显小于河流，位于高海拔地区河流小于低海拔地区河流CDOM的分子量。（3）水质参数对CDOM的光学特征作用明显，不同河流的水质参数与CDOM光学特性之间的相互作用差别较大；土地利用、水文条件、人口分布对黄河流域河湖水体CDOM光学特性影响较大，海拔高度对河流CDOM光学特性作用不大，而对湖泊水体CDOM光学特性显著影响。另外建设用地和人口分布是影响CDOM浓度的主要因素之一。