| As modern industry and agriculture grow rapidly and the living standard of people rise increasingly,large amounts of industrial effluent,domestic sewage and water contains chemical fertilizer and pesticide pollution is discharged into the rivers and poses a great threat to water environment in our country.At the critical time of entering the 13 th five-year period of construction and development,surface water monitoring and control has become the priority to improve the eco-environment of China.There is no doubt that surface water safety is critical to national health,eco-environment stability and sustainable development of social economy.According to the "13th Five-Year" plan of environmental monitoring quality management published by the Environmental Protection Department,by 2020,our country should fully complete the air,surface water and soil environmental monitoring quality control systems.Among them,to refine the technical system,standard of monitoring system,means of quality control technology innovation,automatic monitoring data collection and system of remote quality control are all dependent on the effectively networking of surface water environment monitoring system.However,distribution of monitoring spots in surface water environment or river basin is still sparse in our country.The blind zones are widely existing.Furthermore,those spots can only obtain the water quality information of zones nearby,which cannot reflect data of other important places of the river.The inefficient monitoring also makes information stagnant,which cannot all-weather response to water pollution typically,immediately and cannot make rapid monitoring and early warning of water pollution disasters in the water body.Therefore,obtaining real-time monitoring water quality parameters of water,being timely or dynamic informed about the condition of water environmental quality and tracking water quality information full-time through the construction of wide area monitoring system is the effective way to realize the pollution monitoring of surface water environment.For the reasons above,funded by the Science and Technology Support Program of Sichuan Province(No.2012SZ0111),Chongqing Municipal Education Commission Science and Technology Innovation Project(No.CYS14039)and Sichuan Belam Technology Co.horizontal cooperation research project(1042012920140453),this dissertation mainly solved the problem of spectrum acquisition,spectral noise reduction,spectral turbidity interference compensation,spectrum compression and long distance wireless transmission.It initially established the theory,instrument and method of real-time and automatic surface water quality measuring and monitoring with distributed UV-Vis spectrum method.The main research contents are as follows:1)Deeply and systematically investigated the development of water quality monitoring theory,instruments and methods at home and abroad;analyzed the main methods of water quality monitoring at home and abroad,especially the characteristics and advantages of the UV-Vis spectroscopy for water quality measuring and monitoring;described the current situation,the challenge,and the national management and control plan of water environment in China;pointed out the situation and problems of the existing distributed water quality monitoring system.On this basis,this dissertation put forward a theory of a new generation of water quality monitoring system that combines UV-Vis spectroscopy water quality measurement technology and distributed online monitoring method.2)Analyzed the fundamental theory of the UV-Vis spectroscopy distributed water quality online monitoring system and designed its instrument system and software architecture.Based on this,it developed the node hardware system,communication protocol,database,man-machine interface,monitoring node instrument and monitoring system experimental platform which met the demands of real-time data acquisition,reliable data transmission,convenient data management and scalable software and hardware.This provides a theoretical and technical basis for the follow-up study.3)Studied the key technologies of the reliability and stability of the spectrum acquisition and data transmission of the water quality monitoring nodes.In view of the optical energy loss in water quality spectrum measurement,it analyzed and designed the optical system of spectrum acquisition,optimized the spectral probe structure to decreased light energy loss in the measurement.Facing the challenge that there is low photon efficiency and strong background noise when industrial grade(with low cost)spectrometer is used,the research developed a dual spectral fusion method which collects the short and long optical spectra at the same time and fuse them after noise variance estimating,double optical path gain matching and weighted averaging according to the noise variance distribution.4)Studied the key technologies of the residual nonlinear spectral noise and the data packet loss in the wireless transmission process.For the nonlinear spectral residual noise,this dissertation constructed a two-dimensional spectral matrix by time axis and spectral axis through interval sampling.It removed noises by using spectral denoising algorithm based on dynamic pane and two-dimensional wavelet transform.During the wireless transmission process,it optimized the compressed data reconstruction quality under the condition of data packet missing and improved the efficiency of wireless transmission through the introduction of spectral compression algorithm based on compressed sensing.5)Studied the key technologies of turbidity interference in water quality calculation and the weak performance of existing COD calculation models.In order to ensure quality of water parameters calculation,especially the accuracy of special organic matter content,it studied a UV-Vis spectrum turbidity compensation algorithm basing on Mie scattering theory,which solves the problem of interference of silt and other suspended particles through establishment of particle size distribution function,inversion of extinction spectra in characteristics spectrum of organic pollutants and turbidity compensation by the differential between the suspended particle extinction spectrum and the original spectrum.The research of this dissertation has already been applied on the engineering operation of sample instrument(being verified by specialists of Sichuan Province Technology Department)taken to Sichuan Belam technology Co.It has put professional knowledge of spectroscopy,optoelectronic technology,environmental science,chemical measurement methods,computer technology,wireless sensor network technology and compressed sensing signal analysis and processing technology together,and constructed the key technologies of the on-line measuring and monitoring system for water quality on the surface water environment in China.It has important theoretical and practical significance on further research to build the unattended,wide-coverage,real-time,online and stable distributed UV-Vis spectroscopy water quality monitoring system,complete the water environment safety monitoring system and help to step on the sustainable development road of water pollution prevention. |
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