Design Of In-situ Detection System Of CO₂in Seawater

Carbon dioxide (CO2) is the main source of global warming. As the largest store of CO2, ocean plays an extremely important role for regulating the concentration of CO2in the atmosphere. Measuring the spatial and temporal distribution data of CO2in seawater is quite important in the study of marine carbon cycle, marine ecology and global climate change. Therefore, it is important and necessary to develop a high-precision and low-power detecting instrument for in situ measuring of marine CO2.Based on discussions about domestic and international development of the CO2detecting instrument, a new CO2detector which used optical fiber chemical measuring techniques was designed. By integrating the optics, chemistry, mechanics, electronics and computer technology, the paper developed an automatic detector with low-noise, low-power and low reagent consumption.At last, pH detection experiment and CO2calibration experiment were designed to verify system performance. The results show that the change of absorbance is less than0.0005, the working current of circuit is less than20mA, power consumption when busy is only300m W, and during an operating cycle, reagent consumption is less than2mL, which satisfy the request of in-situ detection.The paper included7chapters:Chapter1described the background and significance of the research, and proposed the research objective and content of this topic.Chapter2introduced the principle of CO2detection with optical fiber chemical method. The relationship between the absorbance and CO2concentration was deduced.Chapter3described the structure design of the instrument as a whole and every single part.Chapter4introduced system hardware design.Chapter5described system software design.Chapter6introduced the experiments and result analysis. Chapter7was a summary of the paper and a prospect for the further research.