Construction And Software Realization Of Characterization Parameters Of Comprehensive Toxicity In Water Based On The Algal Photosynthetic Inhibition

With the intensification of human activities and the rapid development of industry and agriculture,the problem of water pollution has become more and more prominent,posing a serious threat to the safety of human life and aquatic ecosystems.The toxicity detection of water traditionally is complicated in operation and has poor timeliness,which cannot meet the requirements of rapid detection;the photosynthetic fluorescence parameters based on the algal photosynthetic inhibition method have a fast and sensitive response to the comprehensive toxicity in water,but due to the use of complex biological theories,they cannot fully and accurately reflect the causes of different types of toxic substances.The current photosynthetic fluorescence parameters as toxicity response indicators to detect pollutants are limited and the stability of measurement results is insufficient.Therefore,it is an urgent problem to construct characterization parameters that quickly and accurately reflect the comprehensive toxicity in water.In this paper,based on the photosynthetic inhibition effect of algae,the commonly used photosynthetic fluorescence parameters Fv/Fm and PIABS can only reflect the photochemical information of PSII under dark adaptation,and have low sensitivity and poor stability for the detection of comprehensive toxicity in water,as well as limited types of toxic substances that can be detected.Based on the extracted point information of the Chlorophyll Fluorescence Induction Curve(OJIP)and the analysis of the overall difference of curves respectively,the comprehensive toxicity characterization parameters PICTE and PIFCD were constructed.On this basis,the performance of photosynthetic fluorescence parameters Fv/Fm and PIABS in detecting comprehensive toxicity of water was compared and analyzed to verify the validity and advantages of the constructed parameters PICTE and PIFCD.The key parameters were provided for the rapid online analysis of water comprehensive toxicity based on the photo synthetic inhibition effect of algae.The main research work completed in this paper is as follows:(1)The response characteristics of algal OJIP curves under the stress of five different kinds of toxic substances(DCMU,DBMIB,MV,Malathion and Carbofuran)were measured and analyzed.The results show that the characteristic points of the OJIP curve are sensitive to the response of toxic substances,there are obvious differences between the overall OJIP curves,and the degree of difference is positively correlated with the intensity of toxic substances.Based on this,it is proposed to construct the characterization parameters of comprehensive toxicity in water from two perspectives:the extraction of characteristic point information of the OJIP curve and the analysis of the difference of the overall curve.(2)The characterization parameter of comprehensive toxicity in water PICTE based on the characteristic point information of the OJIP curve was constructed.Based on the feature extraction of J,I feature point fluorescence and curve enclosing information of OJIP curve,combined with the time information of feature point for data correction,the characterization parameter of comprehensive toxicity in water PICTE was constructed.The results show that:PICTE has a sensitive response to five toxic substances,and the stability is less than 5%;the minimum detection limit is lower than PIABS by 79.7%,72.82%,61.24%,56.1%and 46.12%,and it can detect high concentration toxic substances.Compared with Fv/Fm,it can detect more types of toxic substances;this study provides a important parameter for the rapid and accurate detection of comprehensive toxicity in water.(3)The characterization parameter of comprehensive toxicity in water PIFCD based on the overall difference of the OJIP curve was constructed.To make full use of the OJIP curve information,the Euclidean distance,the improved piecewise Frechet distance and the cosine similarity feature were extracted respectively,the differences between the OJIP curves of the control group and the experimental group were analyzed,and the differences were evaluated combined with the KNN classification algorithm.Based on the classification accuracy of toxicity intensity with different characteristics,the best combination characteristics were selected.On this basis,the feature weight was adjusted adaptively based on the feature contribution rate algorithm,and the characterization parameter of comprehensive toxicity in water PIFCD was constructed.The results showed that compared with Fv/Fm and PIABS,PIFCD was sensitive to the five toxic substances,and the lowest detection limit was lower than that of PIABS by 90.34%,41.66%,81.91%,95.43%and 77.66%;compared with PICTE,the detection limit was lower,and the relative standard deviation of the stability is about 10%;this study provides a sensitive characterization parameter for the rapid detection of comprehensive toxicity in water.(4)Design and implement the software of a comprehensive water toxicity detection system based on the algae photosynthesis inhibition method.Through the analysis of requirements and the design of software function,the core functions such as serial communication,the assessment of comprehensive toxicity in water,storage and query of data are realized,which provides an operating software for the rapid and accurate measurement of the comprehensive toxicity in water.The results of the paper show that the constructed characterization parameters of comprehensive toxicity in water provide an effective method for the rapid detection and application of comprehensive toxicity in water based on the algal photosynthesis inhibition method.