| Chlorophyll a was regarded as the important indicator to describe the marine primary production because the chlorophyll a content of phytoplankton in the ocean is related to its photosynthesis production. The concentration of chlorophyll a is also the major parameter to evaluate marine water quality, organic pollution and detect the fishing ground, and the temporal and spatial variation of chlorophyll a contains the basic information of sea areas.Now, the developing trend of chlorophyll a fluorometer was miniaturization, low consumption and modularity. The system is based on the fluorescence analysis, the microcontroller MSP430F2013 as the key control module, 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 photosensor 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 noise signal valid. The sampled data would upload to the computer with RS-232 and display real-time.The experimental result shows the concentration of chlorophyll a measured by the system has the linear relation with the fluorescence intensity, and has smaller detection limit and lower consumption. The system adopts the modularity, lower consumption, small volume design decision, this to the benefit of integration of the system and the other sensors, also to the benefit of maintain, installation 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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