基于荧光动力学光谱的浮游植物初级生产力准确测量方法研究

The primary productivity of phytoplankton is the basic link of the material circulation and energy flow of the ecosystem, and its rapid and accurate measurement is very important. Compared with traditional methods, chlorophyll fluorescence technique is a fast and real-time measurement method. However, the chlorophyll fluorescence technique faces two problems in the measurement of phytoplankton primary productivity. First, the photosynthetic rate measured using a single-wavelength excitation light source in the fluorescence kinetics technique cannot represent the photosynthetic capacity of phytoplankton under the actual ambient light. Second, the concentration of phytoplankton photosynthetic reaction centers in unknown water cannot be accurately calculated by using the chlorophyll concentration measured by fluorescence spectrum. These two problems make it’s difficult to accurately quantify the primary productivity. .This project proposes a new method for measuring the primary productivity of phytoplankton based on fluorescence kinetic spectra. The spectra of photosynthetic fluorescence parameters would be obtained by using the chlorophyll fluorescence kinetic spectra. The photosynthetic rate measurement method under photosynthetically active radiation would be studied by combining the actual environmental spectrum. By using the spectra of photosynthetic fluorescence parameters and the photosynthetic rate measurement method, the problems in the accurate measurement of the photosynthetic rate of phytoplankton in unknown ambient light conditions would be solved. The direct measurement method of the concentration of photosynthetic reaction centers using directly related photosynthetic fluorescence parameters would be studied to solve the problems in the accurate quantification for photosynthetic reaction centers in unknown waters. A quantitative model of primary productivity of phytoplankton would be established based on fluorescence kinetic spectra to provide a method foundation for the field rapid detection technology.

浮游植物初级生产力快速准确测量对水环境生态质量评价、海洋资源评估及全球气候变化预测具有重要意义。相比气体交换法，叶绿素荧光技术提供了一种快速实时初级生产力分析手段，但在其关键要素测量中，存在实际光照条件下光合作用速率难以准确测量，以及以叶绿素含量推算光合反应中心浓度存在根本性误差的难题，导致初级生产力准确定量化困难。.项目提出基于荧光动力学光谱的浮游植物初级生产力测量新方法。利用多波长可变快速光脉冲技术测量浮游植物叶绿素荧光动力学光谱，反演获得“光合荧光参数谱”，结合环境光谱研究有效光合辐射内的光合作用速率测量方法，解决实际光照条件下光合作用速率准确测量难题；利用光合反应中心相关荧光动力学参数，基于生物膜能流理论研究光合反应中心浓度直接测量方法，实现未知组分浮游植物光合反应中心浓度准确定量测量；建立浮游植物初级生产力荧光动力学光谱定量算法模型，为发展快速原位检测技术提供方法基础。

浮游植物初级生产力是水生态系统物质和能量的基础，快速准确测量初级生产力对提升海洋碳汇和水生态环境监测评估能力重要科学意义和应用价值。本项目通过研究浮游植物光合荧光参数准确测量方法、光合尺寸单元校正方法，以及光吸收系数校正方法，建立了水体初级生产力荧光动力学准确分析模型，发展了一种基于荧光动力学光谱的初级生产力分析方法；在此基础上，研制了水体初级生产力原位监测仪原理样机，并在太平湖、南海东沙海域、大亚湾海域开展了示范应用验证。取得主要研究成果如下： .（1）构建了浮游植物初级生产力荧光动力学测量实验系统，研究了荧光动力学法光合荧光参数准确测量方法，包括基底信号对光合荧光参数测量结果影响校正方法、激发光强自适应调控方法，以及浊度对光合荧光参数测量影响校正方法，在此基础上，建立了初级生产力荧光动力学理论分析模型。.（2）研究了浮游植物初级生产力测量中光合尺寸单元校正方法。基于激发光谱法实现了混合藻各组分占比测量，实现了混合藻光合尺寸单元准确测量。结果表明，纯种蓝藻、绿藻、甲藻和混合藻类初级生产力测量误差由校正前的38.8%、14.3%和13.2%和15.2%下降至3.9%、4.1%、5.2%和5.2%，有效解决了光合尺寸单元使用固定值带来的初级生产力测量偏差问题。 .（3）在藻类初级生产力吸收模型基础上，用藻类荧光激发光谱表征藻类吸收系数，研究了藻类光能吸收系数校正方法，建立了基于藻类荧光动力学光谱的初级生产力分析模型。结果表明，纯种藻和混合藻校正前后初级生产力模型测量相对误差由3.17%、28.43%下降至5.33%、1.83%，大幅提升了初级生产力测量准确性。.（4）研发了水体初级生产力快速原位监测仪原理样机，并在太平湖、南海东沙海域和大亚湾海域开展了外场示范，快速获取了初级生产力时空分布数据，验证了项目研发核心技术在实际水体初级生产力检测应用中的可行性和有效性，为水体藻类初级生产力快速原位观测、水华和赤潮灾害监测预警，以及水生态状况评估提供了先进技术装备。