Temporal And Spatial Variation Characteristics And Evaluation Of Water Environment Quality In Pu River Basin

As a natural river flowing through Shenyang City and the most important ecological landscape water system of Puhe New City,Puhe River is one of the important water supply sources for socially necessary water.It plays a pivotal role in regional water storage,flood control,improving the ecological environment of the park,creating beautiful historical and cultural landscapes.In recent years,in order to control the water environmental pollution of the Puhe River and improve the water ecological functions of the basin,Shenyang has gradually increased its precise and scientific pollution control,established a list of problems,carried out the Puhe River water ecological comprehensive improvement project,built the Puhe River ecological corridor and promulgated daily management and protection measures.Shenyang has also excavated lakes,built constructed wetlands,carried out river widening and dredging,river channel improvement and bank revetment projects,and clarified the responsibility for governance.The water quality of the Puhe River has been steadily improved.It is of great significance to improve the water ecology of the Puhe River Shenyang Section and promote the construction of regional ecological civilization by conducting a scientific and comprehensive evaluation of the current water quality status of the section,visually displaying the current water quality treatment results of the section,determining the focus of the next improvement of the section water quality,and providing data support and treatment basis for the water quality treatment of the Puhe River Shenyang Section.To this end,one provincial and municipal routine monitoring section was selected in the five provinces through which the Puhe River Shenyang Section flowed,and the monthly monitoring data of each indicator on the selected section of the section in the five years from 2018 to 2022 were collected and sorted.On this basis,the temporal and spatial change trend of water environment quality in the Puhe River Shenyang Section was analyzed and evaluated,and the law of water quality change was mastered.The comprehensive pollution index method,Weber-Fichner evaluation method and principal component analysis method were used as research methods to analyze and compare the advantages and disadvantages of each method.Finally,the most suitable evaluation method for the water quality of the Puhe River Shenyang Section was selected.The results of the study show that:1.The water quality evaluation of the five monitoring sections through which the Puhe River Shenyang Section flows sequentially shows that The overall improvement of water quality in the river section has led to a significant increase in the overall cleanliness rate of water quality in all sections,and phased progress has been made in the water quality control work of the river section.However,the evaluation of sub-indicators of each section shows that the water pollution of the Puhe River Shenyang Section has not been eradicated,and there is still a pollution rebound.Microbial contamination dominated by fecal coliform bacteria and nutrient pollution dominated by nitrogen and phosphorus will be the focus of future water quality control in Puhe River Shenyang Section.2.The water quality of the Xingguoqiao section in the Puhe River Shenyang Section was the best,and the water quality of the Zhaojiatao section,the Puheyan section,the Houjitiqiao section and the Guodaqiao section deteriorated,that is,the water quality in the upper reaches of the section was significantly better than the water quality in the middle and lower reaches,and the water quality in the lower reaches was better than the water quality in the middle stream.Because the upstream Xingguoqiao section is located near the Qipanshan Reservoir,the water resources are abundant,the settled population,agriculture and enterprises in the districts and counties are relatively small,the degree of development and utilization of water resources is relatively low,and the water ecology is relatively intact and healthy.The water quality of the middle and lower reaches of the section is mainly linked to the urban construction and regional economic development,and the water pollution may be related to industrial and domestic sewage,freshwater aquaculture wastewater discharge and the use of a large number of chemical fertilizers and pesticides.At the same time,due to the flat terrain,the water flow is small and the self-purification capacity of the water body is poor.3.There are four main types of pollution in the Puhe River Shenyang Section from 2018 to 2022: aerobic organic matter pollution(chemical oxygen demand,biochemical oxygen demand,permanganate index),nutrient pollution(ammonia nitrogen,total phosphorus),toxic organic matter pollution(fluoride)and microbial pollution(fecal coliform).There were spatial differences in the main pollution types of different sections,Xingguoqiao section was dominated by good maintenance organic matter pollution and microbial pollution.Houjitiqiao section was dominated by aerobic organic matter pollution,nutrient pollution and microbial pollution,and Guodaqiao section.Zhaojiatao section and Puheyan section were mainly based on good maintenance organic matter pollution,nutrient pollution,toxic organic matter pollution and microbial pollution.4.Analyzing the evaluation results of the three water quality evaluation methods,the principal component analysis method can simplify the water quality evaluation data by dimensionality reduction,but the evaluation results are more conservative than the comprehensive water quality evaluation method and the Weber-Fichner evaluation method,and the distinction between high-quality and inferior water is small.The evaluation results of the comprehensive pollution index method and the Weber-Fechner evaluation method show certain similarity as a whole,the water quality classification is more detailed,and the evaluation results are more comprehensive,but the Weber-Fechner evaluation method clearly calculates the weight of each index,the evaluation results are more sensitive,and the evaluation results obtained are more accurate,so it is recommended to use the Weber-Fechner evaluation method for water quality evaluation.