Study On Speciation Characteristics Of Phosphorus In Overlaying Water And Sediment And Eutrophication Of Jiuli Lake

This paper takes the Jiuli Lake National Wetland Park as the research object.Through the 7-month monitoring,it’s spatial and temporal distribution characteristics of water quality indicators are studied.The morphological distribution characteristics and migration and transformation of phosphorus in sediments and water bodies are analyzed.Analysis(RDA)sorts and screens the relationship between various water quality indicators and phosphorus forms in overlying water and sediments,and selects accelerated genetic projection pursuit model(RAGA-PPE)for water quality and eutrophication of Jiuli Lake.Evaluation.(1)The monitoring data indicates that the water quality of Jiuli Lake is poor,and the total water level of surface water is Class IV.The spatial and temporal distribution of water quality indicators is quite different,and there is a strong correlation between water quality indicators.The pH value is significantly correlated with most water quality indicators,indicating that the pH value is an important factor in the water quality of Jiuli Lake.(2)The content and proportion of various phosphorus forms in the overlying water and sediment are quite different.The results of RDA show that there is a strong correlation between various forms of phosphorus in the overlying water and sediments,and the water quality index of the overlying water is an important factor affecting the migration and transformation of phosphorus in Jiuli Lake.(3)The average moisture content of sediments in Jiuli Lake is 38.74%,and the average loss rate is 8.41%.The water content and the loss rate of the deposits between the points differ greatly.The TC/TP ratio of Jiuli Lake is low and negatively correlated with the TP content in sediments,indicating that most of the TP in the sediments of Jiuli Lake originates from the input of agricultural activities.(4)The evaluation results of RAGA-PPE model indicate that the water quality of Jiuli Lake is Class IV water.For the eutrophication degree of Jiuli Lake,the linear interpolation method evaluates to moderate eutrophication,and the RAGA-PPE evaluation results are mild to moderate eutrophication.Compared with the traditional method,the RAGA-PPE model is more in line with the actual situation,and its objectivity and precision are better.(5)During the monitoring period,the ratio of TN/TP in Jiuli Lake was 18.36,and the coefficient of variation was 0.46.The change was more obvious.54.41% of the samples were in the phosphorus-restricted state,and 13.24% of the samples were in the nitrogen-restricted state,indicating that phosphorus is the most important limiting factor for algae growth and eutrophication in Jiuli Lake.