Environment And RemoTe sensing researcH (EARTH) Laboratory, Physics Department, College of Science, De La Salle University Manila, 1004 Taft Avenue, Manila 0922, Philippines.
Division of Physical Sciences and Mathematics, College of Arts and Sciences, Miagao Campus, University of the Philippines Visayas, Miagao 5023, Philippines.
Sensors (Basel). 2022 Apr 12;22(8):2940. doi: 10.3390/s22082940.
Chlorophyll-a measurement is important in algal growth and water quality monitoring in natural waters. A portable pulsed LED fluorescence lidar system based on the preliminary algal organic matter and pigments excitation-emission matrix (EEM) of commercialized AZTEC Spirulina powder at varying concentrations was developed. Fluorescence peaks from EEMs showed increasing intensity as the Spirulina concentration increases. Using this information, an LED fluorescence lidar with a wavelength of 385 nm, pulse width of 10 ns, and repetition frequency of 500 kHz was constructed for chlorophyll detection at 680 nm. Turbidity measurements were also conducted at 700 nm emission wavelength at the same excitation wavelength. Range-resolved fluorescence lidar signals from the portable pulsed LED fluorescence lidar system are highly correlated with the standard methods such as optical density at 680 nm (R = 0.87), EEM fluorescence chlorophyll-a pigment at 680 nm (R = 0.89), and corrected chlorophyll-a concentration (R =0.92). The F680/F700 lidar ratio was measured to provide a linear relationship of chlorophyll-a and turbidity in waters. The F680/F700 measurement showed strong correlations with Spirulina concentration (R = 0.94), absorbance at 680 nm (R = 0.84), EEM chlorophyll-a pigment at 680 nm (R = 0.83), and corrected chlorophyll-a concentration (R = 0.86). Results revealed that this new technique of chlorophyll-a measurement can be used as an alternative to other standard methods in algal growth monitoring.
叶绿素-a 测量在自然水域中的藻类生长和水质监测中很重要。本研究开发了一种基于商用 AZTEC 螺旋藻粉在不同浓度下的初步藻有机物和色素激发-发射矩阵（EEM）的便携式脉冲 LED 荧光激光雷达系统。EEM 的荧光峰随着螺旋藻浓度的增加而增加。利用这一信息，构建了一个波长为 385nm、脉冲宽度为 10ns、重复频率为 500kHz 的 LED 荧光激光雷达，用于在 680nm 处检测叶绿素。在相同的激发波长下，还在 700nm 发射波长处进行了浊度测量。便携式脉冲 LED 荧光激光雷达系统的距离分辨荧光激光雷达信号与标准方法（如 680nm 处的光密度（R = 0.87）、680nm 处的 EEM 荧光叶绿素-a 色素（R = 0.89）和校正后的叶绿素-a 浓度（R = 0.92））高度相关。测量 F680/F700 激光雷达比，提供水中叶绿素-a 和浊度的线性关系。F680/F700 测量值与螺旋藻浓度（R = 0.94）、680nm 处的吸光度（R = 0.84）、680nm 处的 EEM 叶绿素-a 色素（R = 0.83）和校正后的叶绿素-a 浓度（R = 0.86）呈强相关性。结果表明，这种新的叶绿素-a 测量技术可作为藻类生长监测中其他标准方法的替代方法。
