拉曼散射研究三峡库区支流环境变化对水华藻群落演替的影响与机理

The completion of the Three Gorges project has been changing the reservoir water environment, and which improve the growth of aquatic plant algae. The uncontrolled growth and reproduction of algae has led to the water bloom frequently. Under the condition of eutrophication, taking measures to reduce the influences of water bloom, which is caused by algal community succession, and the water bloom predicting in the tributary of Three Gorges Reservoir, have important significance in ecological and environmental fields. Therefore, based on the Raman analysis technique, differences of the configuration change in algal pigments and lipid, caused by stress between algal cells in community succession, are investigated with the most common water bloom algae in three gorges reservoir. Combining the differences with chemometrics methods, the discrimination of the main algae is modeling with small sample support vector machine for classification. And, the promoting or inhibiting effect of environmental changes on N, P, Heavy metal ions, illumination intensity and water turbulence for community succession on main algae growth in eutrophic water are investigated. Then, the evolution laws of Raman fingerprint characteristics for algal lipid and pigment, which is caused by the community succession, have also been analyzed. Thereafter, based on the kernel partial least squares regression algorithm, quantitative analysis of chlorophyll a in tributary is established with Raman fingerprint characteristics spectroscopy. Moreover, the internal dynamic life characteristics of algae in the community succession, physiological and biochemical characteristics of the dominant algal in species competition are explored to predict tendency for community succession in the tributary of the Three Gorges Reservoir under the conditions of eutrophication. At last, the sufficient conditions for the tributary water bloom are described to forecast and control of water bloom in the Three Gorges Reservoir.

三峡工程的竣工，引起库区水环境发生变化，水生浮游藻类大幅度繁殖，导致近年来频繁水华。研究富营养化条件下群落演替引起的水华机制及预测库区支流水华，进而采取措施减少其带来的影响具有重要的生态和环境意义。本项目拟以三峡库区常见水华优势藻为研究对象，基于拉曼光谱分析技术，挖掘群落藻细胞间胁迫引起的不同色素、脂质构型构象的差异，建立基于小样本支持向量机的优势藻判别分析方法；研究库区支流富营养化条件下环境变化影响因子如含氮磷污染物、重金属离子、光强、水体紊动等对浮游藻群落演替的促进或抑制机制，分析群落藻色素和脂质的拉曼指纹特征演变规律，建立水体叶绿素a含量核偏最小二乘回归分析模型；探讨富营养化条件下群落演替过程藻群落内部动态生命特征及藻类种群竞争中占优的生理生化特征规律，对群落演替趋势进行预测，进而阐述库区支流水华的充分条件，为三峡库区支流水华的预警、防治提供基础和研究依据。

针对三峡库区水华问题，采用拉曼光谱分析方法，开展了水华微囊藻细胞的拉曼指纹表征、藻细胞种类鉴别及藻细胞生长状态的评估研究，探讨库区支流富营养化条件下环境变化影响因子如含氮磷污染物、光强、水体紊动等影响因子对藻细胞胞内色素的影响，分析环境变化影响因子引起的群落藻色素指纹特征的演变规律。基于种群进化优胜劣汰的思想，提出了一种基于遗传算法的拉曼光谱基线校正算法，解决拉曼光谱复杂基线背景干扰问题。基于化学计量学理论基础，采用多元主成分分析、判别式偏最小二乘和小样本支持向量机分类算法，建立了基于共振拉曼光谱的库区支流群落演替过程优势藻种判别分析、藻细胞生长期判别分析、水环境扰动评估分析及藻细胞胞内类胡萝卜的含量评估分析方法，实现了不同藻细胞种类、藻细胞生长阶段的鉴别，并对水环境扰动及藻细胞胞内类胡萝卜素含量进行了评估。此外，项目开展了水华微囊藻细胞凋亡中产生的微囊藻毒素检测技术的研究，评估了水体污染物及微囊藻毒素异构体对微囊藻毒素MC-LR检测的影响，实现了10-6mg/L MC-LR的检测。综上，通过对藻细胞类别的鉴别及藻细胞生长状态的评估及微囊藻毒素MC-LR的检测，可对水体富营养化水平进行预判，监测水华现象，保障饮用水安全，为水华机理研究及其防治提供一定的理论支撑。