滇池北部小型封闭水域草藻稳态转换过程中的沉积物-藻-草相互反馈作用机制研究

The feedback among sediment, algae and vegetation is the main reason for the hysteresis of the restoration of eutrophic shallow lakes. While currently there is still absence of deep understanding on the feedback mechanism. The northern region of Dianchi Lake is under serious algal blooms, which is deserved for a deep study. The main environment factors to drive regime shift in high nutrient load and the mechanism of feedback among sediment-algae-vegetation is revealed based on mecosem experiment and field monitoring. Four parts were included in the proposed study. The fist is about the temporal variability and influential factor of the water quality and aquatic ecosystem in the small sealed water body. The second is about the temporal characteristics of the surface sediment microenvironment in "algae-vegetation" regime. The third is about the influence of surface sediment microenvironment on the sediment nutrient release and algae growth kinetics. The fourth is about the temporal variability and key mechanism of the feedback among "algae-vegetation" in small enclosed water body. The proposal aims to reveal the mechanism of the feedback among sediment-algae-vegetation, and to evaluate the function of the mechanism in regime shift of eutrophic shallow lakes. It is believed that the findings and the approach proposed in this study will provide more interesting and useful hints to support restoration ecology of eutrophic shallow lakes.

"沉积物-藻-草"三者之间复杂的相互反馈作用是富营养化浅水湖泊生态修复过程迟滞乃至逆转的重要原因，但三者相互反馈的作用机制尚未有一致性的结论，研究尚不够深入。本项目选择滇池湖区北部蓝藻爆发和堆积区作为研究对象，以围隔实验作为主要的研究手段，研究较高营养负荷条件下驱动湖泊发生藻-草稳态转换的关键环境要素，重点关注富营养化水体中沉积物与藻草稳态转换的驱动-反馈机制。主要研究内容包括：①小型封闭水域水质、水生态特征指标的时间尺度变化及影响因子分析；②"藻-草"共存稳态下表层沉积物微环境的周年性变化规律研究；③微环境理化因子变化对沉积物营养盐释放及藻类生长动力学过程的影响研究；④小型封闭水域"藻-草"相互反馈的关键机制识别及随时间的变异性。本项目旨在通过小型封闭水域的典型案例研究，了解沉积物-藻-草相互反馈作用机制在富营养化浅水湖泊稳态转换过程中的作用，为我国富营养化浅水湖泊生态修复提供理论支持。

本项目分析了滇池北部小型封闭水域内水体和沉积物中氮磷营养盐含量，并进行了对应的藻类和水生植物生长模拟实验，得出以下结论：.1）滇池北部小型封闭水域内沉积物氮磷有潜在释放可能性。.2）上覆水的扰动对沉积物氮磷释放和蓝藻生长有一定促进作用，其中较强的扰动促进效果相对明显。光照对蓝藻生长具有一定促进作用，而相对较高的蓝藻生物量对沉积物中磷的释放有促进作用。上覆水中相对较高的溶解氧对沉积物中氮的释放存在抑制作用，对蓝藻生长的影响比无明显规律。.3）四种选用的水生植物，对水体中氮磷皆有一定吸收作用，其中美人蕉对水体中氮磷营养盐吸收效果最好。水体中氮磷营养盐对美人蕉和水葫芦的生长有促进作用，对旱伞竹和大黑豆的生长有抑制作用。4种水生植物的各组织对氮磷营养盐的贮存能力很弱。