Theoretical And Experimental Studies Of Online Water Quality Analytical Method For Seawater

In recent decades,the environmental pollution,especially water pollution,have became a hot spot of the society.In our country,there are large areas of coastal waters been contaminated,red tides occur frequently and eutrophication is constantly appearing,all of them make The ocean environment facing a grim circumstance.To protect our environment,we need to realize long-term sea water pollution monitoring in-situ.At present,most of the detection use chemical measurements to gain parameters of water pollution in seawater,which costs a long time and needs lot of reagents which can cause secondary pollution at the meantime.So it's not suitable for batch and long-term measurements of water samples.As a purely physical optics method,UV water quality testing method does not require chemical reagents and never product secondary pollution.It can provides continuous real-time monitoring and response to dynamic changes of water quality parameters in time.In this paper,the full UV absorption spectrum obtained for one time can reflect the water pollution more comprehensively.The method,using a combination between principal component scores and euclidean distance,is proposed to classify water samples in this paper,the feasibility of which is verified by applying it for classification different types of water,such as rivers,lakes and oceans.Depending on the absorption characteristics of organic and inorganic substances,making potassium hydrogen phthalate representing chemical oxygen demand(COD)and potassium nitrate representing nitrate nitrogen as models,this paper discusses the main component trends for the same kinds of solutions with different concentrations.Then this paper use a variety of models,for example single wavelength,dual-wavelength,multi-wavelength,spectral area and scores based on the full spectrum of the principal component,to analyze the COD concentration,proposes the method of using the combination between principal component scores based on UV absorption spectrum and the least squares for predicting the COD concentration,which is showed good feasibility of water quality testing by the analysis of COD and nitrate nitrogen in actual sea water samples,the results of which are reliable.Using principal component analysis(PCA)based on UV absorption spectrummodeling can take more influence of components variation into account and remove the external interference in maximum.It also can obtain more exact concentration of water quality parameters.So the PCA provides a more suitable method for water quality monitoring.