Study On Endogenous Pollution In Shenwo Reservoir

The reservoir is a large-scale water conservancy project with many functions such as flood control,water storage and power generation,irrigation and aquaculture,and has important social and economic significance.As a large reservoir in Liaoning Province and an important reserve water source,the Shenwo Reservoir has improved the water quality of the reservoir area and improved the water supply function.This is an important issue facing the Shenwo Reservoir.In this thesis,the Shenwo Reservoir was taken as the research object,and six points were set in the reservoir area for water quality sample collection,and three points were set for sediment collection.The various organic substances,heavy metals and typical water quality indicators in the samples were tested to comprehensively analyze the overall water environment pollution of the reservoir.Focus on the study of the internal pollution of the reservoir,identify the typical types of pollutants and pollution,and through the stratified analysis of sediments,explore the distribution of pollutants in sediments and the release of sediments.The main findings were as follows:?1?The water body of the Shenwo Reservoir was alkaline and the dissolved oxygen concentration of the water reached the Class I water standard of surface water.The concentration of BOD₅ in the water fluctuated with time,which was at the lowest point in 2013 and the highest point in 2015.The concentration of ammonia nitrogen in the water showed a downward trend with the year.The total phosphorus content of the reservoir had a strong change with time and higher total phosphorus concentration presented in 2013 and 2014.The total nitrogen concentration in the Shenwo Reservoir exceeded the standard and the annual average concentration reached 2.00 mg/L.The highest concentration was 2016,and the annual average concentration reached 6.00mg/L.The indicators that seriously affect water quality in water bodies were mainly total nitrogen and total phosphorus.A comprehensive evaluation of the water pollution situation in the reservoir area showed that the water pollution in the reservoir area of the Shenwo Reservoir was in a mild to moderate pollution state.?2?Distribution of pollutants in the sediments of the reservoir area:In the spatial distribution,the content of organic naphthalene and anthracene in each point was seriously exceeded,and the content of strontium in the inlet of the river was not detected,and phthalic acid diester?DOP?The content was relatively low at each point,and the mean was slightly larger than the risk control value.The contents of heavy metals such as arsenic,nickel and lead far exceed the risk control value,It was content,Reservoir center>fine river inlet port>Taizi River entrance,the heavy metal copper content was less than the standard.In the time distribution,by analyzing the changes of pollutant concentration at different depths of sediments,it could be seen that the content of naphthalene and anthracene in organic matter was increasing toward the surface layer.The content of phthalic acid diester?DOP?generally fluctuated around the risk control value,and the concentration did not change much over the years.The contents of heavy metals such as copper,nickel and lead were more stable with the increase of sediment depth,and the content of heavy metal arsenic increased toward the surface layer.Correlation analysis between the pollutants in the sediments of the reservoir area showed that the organic naphthalene had a strong positive correlation with the strontium.There was a significant positive correlation between the heavy metals As-Cu.The heavy metals Ni and naphthalene and strontium had A certain positive correlation.?3?Different pH environments had different effects on the release of pollutants in sediments.When pH=9,the release of nitrogen was the largest in the sediment,and the COD concentration in the overlying water reached the highest.When pH=7,the release of phosphorus was the largest in the sediment.Different temperature conditions played an important role in the release of pollutants in sediments.When the ambient temperature rised from 5°C to 30°C,the rate of nitrogen and phosphorus released by the sediment over the water increases significantly,and the COD concentration also increased with temperature.