基于光敏反应的秸秆分解产物复合化感抑藻机理研究

Using straw to inhibit algae and cyanobacterical growth in water body is an environmentally friendly and low-cost technology, so developing this technology has practical significance for the algae and cyanobacteria control in water environment in our country. The active organic ingredients of straw decomposition products are considered as the major algistatic or algicidal agents, which may imply a complex mechanism involving direct toxic inhibition and indirect photosensitive inhibition for phytoplankton cells. However, at present the poor understanding of indirect photosensitive inhibition mechanism, in particular the position and effect mechanism of photosensitive reactions caused by solar radiation in straw complex allelopathic inhibition mechanism, cannot provide exact theory support for this technology. In this project two common straws in South China, barley and rice straw, will be selected as research materials. A series of methods, such as spectrum analysis of straw decomposition products, determination of apparent quantum yield of reactive oxygen species, phytoplankton photosynthetic yield, characterization of algal cell membrane permeability, reactive oxygen species quenching, intends to be carried out to investigate the complex allelopathic inhibition algae mechanism of straw decomposition products from some terms including the process of straw decomposition and its organic products, photochemical formation of reactive oxygen species from straw decomposition products, mechanism of algae inhibition by reactive oxygen species, and selective effect of inhibition for different algae species, which can provides theoretical basis and guidelines for practical application of algae control in water resource.

秸秆化感抑藻具有绿色环保、成本低廉的优势，深入研究秸秆抑藻机理对于秸秆抑藻技术的应用和推广显得尤为重要。秸秆分解产物中的活性有机成分被认为是抑藻的主要物质，近些年研究表明它们对藻类抑制机理可能是一种包含直接毒性抑制和间接光敏抑制的复合化感抑制机理，然而目前对太阳光辐射所引发的光敏反应在秸秆复合化感抑藻中的作用机理还缺乏认识，秸秆抑藻缺乏明确的理论支持。本项目拟选取我国南方常见的大麦杆和稻杆为材料，在通过光谱分析秸秆分解产物的基础上，采用室内模拟光辐射和室外太阳光辐射对秸秆分解产物对藻类的直接毒性和间接光敏抑制效能进行分析，从活性氧生成速率和表观量子产率角度对分解产物光敏生成活性氧进行评价，进一步采用藻类光合作用产率和藻细胞膜渗透性表征、活性氧淬灭技术来研究秸秆分解产物复合化感抑藻机制，从光敏活性氧选择性抑藻方面揭示秸秆分解产物抑藻差异性，为其更好地在藻类污染水源应用提供理论基础。

本项目针对秸秆分解产物对水华藻类的光化学抑制机理进行研究。对三种常见的农作物秸（稻秆，大麦秆，小麦秆）腐烂分解产物的结构及光化学特性进行了研究发现，秸秆分解产物中均含有醌类和酚类官能团，能够吸收光子能量发生光敏反应，并且证明了秸秆的分解产物在UV光照辐射下对研究对象铜绿微囊藻的生长具有抑制作用。三种秸秆中好氧分解的样品过氧化氢和单线态氧产量均高于自然分解的，大麦秆通过光化学反应产生过氧化氢的能力显著高于小麦和水稻两种秸秆以及标准天然有机物腐殖酸和富里酸，而小麦秆分解产物的单线态氧生成能力则高于其他秸秆分解产物。对铜绿微囊藻的生物测试试验表明，三种秸秆分解产物在模拟太阳光光照下均能通过生成过氧化氢和单线态氧对藻类生长产生抑制，但是由于过氧化氢能够较为稳定的存在于水体，其对铜绿微囊藻的生长抑制占主导作用。本研究揭示了秸秆抑藻过程中光敏反应生产活性氧在藻类抑制中的作用机理，为农作物秸秆在水环境藻类污染治理工程提供了理论依据和新思路。