Pollution Characteristics Of Sediment Nutrients And Simulation Study Of Nitrogen And Phosphorus Release In Mingcui Lake

In recent years,with the gradual control of lake's exogenous pollution,the endogenous sediments' effect on lake eutrophication become more and more obvious.As a relatively closed inland shallow lake in the northwest city,Mingcui Lake has beard more serious pollution.Therefore,in order to reveal the pollution characteristics of sediment and water nutrition,and the release rule of nitrogen and phosphorus,this paper uses the combination method of actual monitoring and simulation experiments combined to analyze the spatial distribution characteristics and the changing rule of different seasons of sediment,water nitrogen,phosphorus and organic carbon,and to evaluate the pollution of nutrients,to investigate the influence of Mingcui lake sediment through the correlation of nutrients sediment and water nutrition.In order to analyze the release characteristics of nitrogen and phosphorus,to reveal the influence of different hydrodynamic condition and different time on the transport process of nitrogen and phosphorus,the author begin an indoor simulation experiment on the release of nitrogen and phosphorus to prove the main function of endogenous pollution on changing water ecological environment.There are the following conclusions:1)the pollution characteristics of sediment nutrientsThe pollution characteristics of sediment and nutrient changes through seasons.The spatial distribution of pollution concentration has obvious differences.The area near reed and the area of water supplement is higher,then open water area and the east part of the lake is lower.The coupling analysis of nutritive salt shows that there is an obvious correlation of carbon,nitrogen and phosphorus.Because of the C/N value and the characteristics of the lake,it shows that there are two kinds of pollution source of sediment,they are land-based input and higher plant in the lake.The pollution index result of sediment and organics show that the pollution in reed area is the highest and then the water supplement area,the last one is the open area.2)the pollution characteristics of water nutrientsStudy on Mingcui lake nutrient pollution' characteristics showed that the concentration of nutrients in sediment interstitial water was significantly higher than the concentration of the overlying water.The concentration gradient of interstitial water and overlying water is significant,and it has the necessary conditions for the release of nutrients from the sediment to the overlying water.Distribution characteristics and seasonal trend at the same time,sediment and nutrients in the interstitial water has a certain similarity,the content of nutrients in overlying water are affected by the complex outside factors,and interstitial water in the seasonal changes of consistency is not obvious.3)the correlation between sediment and water nutrientsMingcui lake sediment-interstitial water-correlation analysis between overlying water nutrients showed that correlation between sediment and interstitial water nutrients is significant during summer and autumn,and lower in spring and winter.And that means there is a close relationship between the nutriture of Mingcui lake and the release of that of sediment and nutrient.Compared the results of domestic east typical lakes and Mingcui lake,and its characteristics of long-term stability of exogenous supply,that can further explain the role of sediment in water "source".However,the correlation between sediments and nutrients in the overlying water was low,which indicated that the pollutants in the overlying water were affected by various factors,such as lake flow,human and wind waves.4)the release characteristics of nitrogen and phosphorus in sedimentUnder static conditions,the release of nitrogen has a characteristics of:fluctuation,it changes from fast to slow and then relatively stable.The release amount of nitrogen is small,and show a negative release in the simulation experiment.The release rate of phosphorus changed from fast to sharply decrease and then become relatively stable.The total release of nitrogen and phosphorus in one day showed characteristic of the interface and lower part higher than that the middle and upper class;during a long time,the release amount presented from higher release rate in the previous experiment to gradually balance at the end of the experiment.The total phosphorus release was lower,and the adsorption was the main one.That under static condition,Mingcui lake sediments are mainly phosphorus adsorption.Under different hydrodynamic conditions,the release amount of nitrogen and phosphorus in a short period of time showed the characteristics of high speed to middle speed to low speed.The greater the disturbance intensity,the greater the release rate.The release amount and release rate of nitrogen and phosphorus showed different trends under different disturbance.Over a long period of time,the amount of nitrogen and phosphorus released in the early stage of the experiment also showed the characteristics of high speed to medium speed then to low speed,finally gradually in a dynamic equilibrium state.The variation of the amount of nitrogen and phosphorus release caused by different disturbance intensity showed some similarity with the change of time.