Gan Tingting, Yin Gaofang, Zhao Nanjing, Tan Xiaoxuan, Wang Ying
Key Laboratory of Environmental Optics and Technology, Anhui Institute of Optics and Fine Mechanics, Hefei Institutes of Physical Science, Chinese Academy of Sciences, Hefei 230031, China.
Science Island Branch of Graduate School, University of Science and Technology of China, Hefei 230026, China.
Toxics. 2023 May 19;11(5):468. doi: 10.3390/toxics11050468.
Heavy metals as toxic pollutants have important impacts on the photosynthesis of microalgae, thus seriously threatening the normal material circulation and energy flow of the aquatic ecosystem. In order to rapidly and sensitively detect the toxicity of heavy metals to microalgal photosynthesis, in this study, the effects of four typical toxic heavy metals, chromium (Cr(VI)), cadmium (Cd), mercury (Hg), and copper (Cu), on nine photosynthetic fluorescence parameters (φ, Ψ, φ, δ, Ψ, φ, F/F, PI, and S) derived from the chlorophyll fluorescence rise kinetics (OJIP) curve of microalga , were investigated based on the chlorophyll fluorescence induction kinetics technique. By analyzing the change trends of each parameter with the concentrations of the four heavy metals, we found that compared with other parameters, φ (maximum photochemical quantum yield of photosystem II), F/F (photochemical parameter of photosystem II), PI (photosynthetic performance index), and S (normalized area of the OJIP curve) demonstrated the same monotonic change characteristics with an increase in concentration of each heavy metal, indicating that these four parameters could be used as response indexes to quantitatively detect the toxicity of heavy metals. By further comparing the response performances of φ, F/F, PI, and S to Cr(VI), Cd, Hg, and Cu, the results indicated that whether it was analyzed from the lowest observed effect concentration (LOEC), the influence degree by equal concentration of heavy metal, the 10% effective concentration (EC), or the median effective concentration (EC), the response sensitivities of PI to each heavy metal were all significantly superior to those of φ, F/F, and S. Thus, PI was the most suitable response index for sensitive detection of heavy metals toxicity. Using PI as a response index to compare the toxicity of Cr(VI), Cd, Hg, and Cu to photosynthesis within 4 h by EC values, the results indicated that Hg was the most toxic, while Cr(VI) toxicity was the lowest. This study provides a sensitive response index for rapidly detecting the toxicity of heavy metals to microalgae based on the chlorophyll fluorescence induction kinetics technique.
重金属作为有毒污染物，对微藻的光合作用有重要影响，从而严重威胁水生生态系统的正常物质循环和能量流动。为了快速、灵敏地检测重金属对微藻光合作用的毒性，本研究基于叶绿素荧光诱导动力学技术，研究了四种典型有毒重金属，即铬（Cr(VI)）、镉（Cd）、汞（Hg）和铜（Cu）对微藻叶绿素荧光上升动力学（OJIP）曲线得出的九个光合荧光参数（φ、Ψ、φ、δ、Ψ、φ、F/F、PI和S）的影响。通过分析各参数随四种重金属浓度的变化趋势，我们发现与其他参数相比，φ（光系统II的最大光化学量子产率）、F/F（光系统II的光化学参数）、PI（光合性能指数）和S（OJIP曲线的标准化面积）随每种重金属浓度增加呈现相同的单调变化特征，表明这四个参数可作为响应指标来定量检测重金属的毒性。通过进一步比较φ、F/F、PI和S对Cr(VI)、Cd、Hg和Cu的响应性能，结果表明，无论是从最低观察效应浓度（LOEC）、等浓度重金属的影响程度、10%有效浓度（EC）还是半数有效浓度（EC）分析，PI对每种重金属的响应灵敏度均显著优于φ、F/F和S。因此，PI是灵敏检测重金属毒性最合适的响应指标。以PI作为响应指标，通过EC值比较Cr(VI)、Cd、Hg和Cu在4小时内对光合作用的毒性，结果表明Hg毒性最大，而Cr(VI)毒性最低。本研究基于叶绿素荧光诱导动力学技术，为快速检测重金属对微藻的毒性提供了一个灵敏的响应指标。
