Research And Design Of A Submersible In-situ Fluorescence Array Organic Matter High Precision Detecting System

Precise in-situ monitoring of chlorophyll-α(Chl-α) and colored dissolved organic matter (CDOM) has important scientific and practical value. The main challenge of Chl-αand CDOM in-situ measurement is the stable long-term low concerntration precise monitoring in natual enviornment. Devices suitable for such in-situ applications shall meet the requirement of high precision, high sensitivity, high stablility, low power comsumption and small size.Combining the modern low power technology and the results of submersible organic matter in-situ measurement researches in recent years, this dissertation proposed a methord of multiple excitation and emission array fluorescence in-situ detection. With the controlling and acquisition circuits and water tight enclosure, a submersible fluorescence detecting system is designed, which is capable of multi-component organic matter concernctration monitoring and features high precision, low power, small size and high pressure resistance.The main tasks and results of this dissertation are summarized as following:1. The fluorescence characteristics of Chl-αand CDOM was analyzed, beased on the principle of three-dimension fluorescence spectrum, a methord of a methord of multiple excitation and emission array fluorescence in-situ detection was proposed.2. The noise model of photoelectric detection circuit and the influence to the measurement result by the environment interefence was investigated, a design of high dynamic range, high presicion photoelectric detection was presented.3. The power comsumption of the modules in the system was analyzed, a way to calculating a new coefficient named power contribution coefficient (PCC) was presented. PCC was used to reduce the total power of the system, prolonging the battery duration.4. A submersible in-situ fluorescence array organic matter detecting system was developed. Laboratory and field tests were made to fully evaluate the performance of the system. The effective measurement range of Chl-a was 0.02～100μg/L, and the effective measurement range of CDOM was 0.1～500QSU. Battery life with 10s interval was up to 3 months.The measurement results were compared with the global famous submersible fluorometer products duiring the tests in the West Lake (Hangzhou) and Xiangshan harbor (Ningbo), which showed high consistency. The measurement accuracy, battery life had reached the highest level of the contemporaneous commercial products.