| Chlorophyll a was regarded as the important indicator to describe the marine primary production because of that the chlorophyll a content of plants in the ocean is related to its photosynthesis production. The concentration of chlorophyll a is a major parameter to evaluate marine organic pollution, water quality and detect the fishing ground, even the temporal and spatial variation of chlorophyll a contains the basic information of sea areas.Now, the developing trend of chlorophyll a fluorometer was low consumption miniaturization, and modularity. And the fluorescence analysis is suitable for the developing. The system is based on the fluorescence analysis, by controlling the ultra-high brightness LED which wavelength is 460nm to excite chlorophyll a to produce the fluorescent signal, and adopt the high performance photo sensor S8745-01 as the induction system of the fluorescent signal. The system uses active low-pass filter to reject noise, and amplifying signal through two stage amplifying circuit, and input the microcontroller after analog-digital conversion, and completes the sampling and integral of measurements many times to filter the noisy signal valid. The sampled data would upload to the computer with RS-232 and display on real-time.The data of the result shows the concentration of chlorophyll a measured by the system has smaller detection limit and has the linear relation with the fluorescence intensity and lower consumption. The system adopts the modularity, lower consumption, small volume design decision, so to the benefit of integration of the system and the other sensors, also to the benefit of installation, maintain and debugging. In addition, Chlorophyll a fluorometer could be used in mooring measurement and profile measurement, so it could measure the vertical distribution of chlorophyll a in one point of sea area, also could measure the spatial distribution of sea area, thus it has important significance for researches of chlorophyll a distribution in the sea areas. |
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