Study On Phosphorus Form Distribution And Adsorption-release Characteristics Of Sediments In The Qiuxi River

The Qiuxi River is located in Renshou County,Sichuan Province.It is a tributary of the tributary of the Minjiang River.The section of the Qiuxi River mouth that merges into the Minjiang River is the national examination section.In recent years,the total phosphorus in the water of the Qiuxi River has exceeded the standard seriously.The phosphorus behavior at the sediment-water interface is one of the important reasons for the change of phosphorus concentration in the overlying water.The physical and chemical properties of the sediments in the dry seasons of the dry,flat and abundance,and the distribution characteristics of various forms of phosphorus There are large differences in the phosphorus concentration of the overlying water and the external environmental factors.These differences will lead to a significant difference in the adsorption and release characteristics of phosphorus in sediments in each water period.Taking the Qiuxi River Region as an example,the phosphorus in the sediments of each water period was taken as the research object,through the detection of the phosphorus concentration in the overlying water and the phosphorus content in the sediments,the phosphorus form analysis of the sediment and the phosphorus adsorption release.The indoor simulation study explored the distribution of phosphorus forms and the adsorption and release of phosphorus in different water periods,and provided scientific basis for controlling the phosphorus concentration in the waters of the Qiuxi River Region and similar small watersheds.The main conclusions are as follows:?1?Phosphorus pollution in the Qiuxi River during the dry season is serious.In the water period of the Qiuxi River Region,the overlying water and sediments are most polluted by phosphorus in the dry season.The TP concentration of the overlying water at each sampling point is 4-8 times higher than the standard phosphorus standard of the Class III water quality.The high total phosphorus content has low ecological risk,and Beidou Town has high ecological risk.The distribution of phosphorus forms in sediments in different water periods is quite different.Calcium and phosphorus?Ca-P?is the main content in dry and flat water period,accounting for more than 50%of total phosphorus content.Calcium and phosphorus?Ca-P?in high water period Organic phosphorus?OP?is dominant,and both accounts for more than 85%of total phosphorus.?2?Sediments are released in each water period.The maximum adsorption of phosphorus on the overlying water by sediments is significantly affected by the different physical and chemical properties of the sediment itself,and is also affected by the phosphorus content of the sediment itself and the distribution of various phosphorus forms.According to the Langmuir formula,the values of EPC₀ in the dry,flat and high water period are larger than the SRP concentration in the overlying water in the actual sampling of each water period,indicating that the sediments in the Qiuxi River Region are generally released in each water period.According to the sediment phosphorus release risk index?ERI?,the sediments in the dry and flat waters of the Qiuxi River are highly risky,and the sediments in the wet season are moderately risky.?3?Environmental factors have different effects on the phosphorus release process of sediments in each water period.Different environmental factors:pH,DO,temperature,and disturbance intensity all affect the release process of sediment phosphorus.The difference in phosphorus distribution in sediments leads to the release rate,maximum release,and equilibrium under different environmental factors.The difference in time and other aspects;the difference in the phosphorus content of sediments will affect the maximum release of sediment and the concentration of phosphorus in the overlying water when equilibrium is reached.The greater the difference in phosphorus distribution of sediments,the release process of phosphorus.The difference in response to different conditions of the same influencing factor is also greater.?4?The maximum release and release rate are related to the distribution of phosphorus forms in sediments.The maximum release of sediments in the Buxi River has a large difference,and there is a significant positive correlation between the maximum release and the phosphorus content,and the release of the sediment with higher phosphorus content is stronger.The quasi-first-order kinetic equation has a good fitting effect on the phosphorus release from sediments.The difference in phosphorus distribution between sediments in each water period leads to a significant difference in the phosphorus release rate at each stage of the reaction.