广东省典型湖泊叶绿素浓度垂向变化模型及影响机制

叶绿素浓度垂向变化影响遥感反演精度和富营养化评价。湖泊水体叶绿素浓度影响因子众多,其垂向变化规律仍是当前的研究难点。以广东省3个典型湖泊的叶绿素浓度、营养盐浓度、藻种及粒径结构等数据,分析了叶绿素浓度垂向变化规律与影响机制,并用不同函数来拟合建模。结果表明：各水体不同时期拟合函数各异,需要分时间、分区域讨论;浅水区域（或浅水湖泊）叶绿素浓度自上而下先减后增,用傅立叶变换拟合效果佳;深水区域的规律是自上而下递减明显,用高斯函数拟合效果较好。浅水区域,光照和水温对垂向浓度的影响在本研究中体现不明显,但营养盐及底泥对其影响较明显;深水区域的垂向浓度变化是藻种、水温、营养盐等因子共同作用的结果。

Vertical variation model and influence mechanism of chlorophyll concentration in typical lakes of Guangdong province

The vertical variation of chlorophyll concentration influences the accuracy of remote sensing inversion and the result of eutrophication evaluation. The law of vertical variation of lake water’s chlorophyll concentration is still a difficult problem in current study because of the complexity of its influencing factors. In this study, we firstly collected water samples from Xinfengjiang Reservoir, Dongshan Lake and Liuhua Lake in Guangdong province to count the species and particle size of algae on the basis of eliminating the disturbance of water body, turbulence and bad weather conditions. Meanwhile, the chlorophyll concentration, temperature, sediments and the nutrients at different depths of each station were measured, respectively. Then several different functions were used to model the rule of vertical variation of the chlorophyll concentration in different parts of lakes. The results show that the fitting function varies with different conditions of lakes, especially for large lakes which may contain various water types: For the shallow lakes, such as Dongshan Lake and Liuhua Lake, the average concentration of chlorophyll is high. And the differences among those samples of shallow lakes are small. With the increase of water depth, the chlorophyll concentration decreases firstly, then increases. The minimum value was observed at the middle of depth. Thus, the Fourier functions perform the best at modeling the rule of vertical variation. The phenomena occur in the shallow region of Xinfengjiang Reservoir which belongs to deep lakes. For the deep lakes, such as Xinfengjiang Reservoir, the average concentration of chlorophyll is low in deep region. The chlorophyll concentration descends obviously with the increase of water depth in the deep region of Xinfengjiang Reservoir, and the Gauss function can express this variation well with the small residual. Finally, we analyze the effect of nutrients, light, water temperature and sediments on the vertical distribution of chlorophyll concentration. For shallow lakes and the shallow regions of deep lakes, the delamination of algae is not obvious. Nutrients and sediments have obvious effects on the vertical concentration of chlorophyll, while the effects of light and water temperature are not clear. In the deep regions of deep lakes, the law of delamination of algae can be seen clearly. The vertical concentration of chlorophyll in deep water area is the result of a combination of algae species, water temperature, nutrients and other factors.