In Situ Measurement Of Total Organic Carbon In Seawater Based On Chemiluminescence

Total organic carbon(TOC)in seawater is a comprehensive index reflecting the degree of organic pollution in water.It represents the total amount of organic matter in seawater by carbon content,and is an important part of marine environmental observation elements.At present,the TOC detection of seawater still relies on the method of on-site sampling to the laboratory for analysis.The analysis method under laboratory conditions has the disadvantages of complex operation,time-consuming and poor timeliness.With the implementation of the national marine strategy and the emphasis on the marine environment,new TOC detection methods are needed to overcome the long-standing problems of insufficient sampling and in-situ monitoring.Therefore,the research of TOC in situ monitoring technology is of great significance to the observation of marine ecological environment.In this paper,the principle of ozone oxidation chemiluminescence is applied to the in-situ monitoring and analysis of seawater TOC,and the in-situ measurement of seawater TOC is realized.By studying the chemiluminescence system of ozonation,the mathematical model of correlation between the integral value of kinetic curve and TOC content in seawater was deduced.Based on the model,a low light level signal processing module is designed.By amplifying,filtering,AD conversion processing,the low light level signal is effectively collected.At the same time,the wavelet threshold de-noising algorithm of improved threshold function is used to de noise the in-situ monitoring data of TOC,which solves the influence of the peak signal caused by the formation of large particles of algae in water samples,and improves the accuracy and representativeness of the data.Finally,a prototype based on ozonation chemiluminescence method was built and performance verification test was carried out.The performance index of the prototype is proved by sea test,the measurement range is 0.1 mg/L～7 mg/L,the measurement accuracy is(0.1 mg/L～1 mg/L)± 0.05 mg/L,(1mg/L～7 mg/L)± 5%,the precision(RSD%)is less than 5%,and the detection limit is 0.05mg/L.The experimental results show that the chemiluminescence principle of ozonation can be applied to the in situ monitoring of TOC in seawater.