Study On Nitrogen Flow And Nitrogen Loading In Water Environmental In The Yangtze River Basin

Nitrogen,in various forms are widespread in the natural environment system of the essential elements,but excessive nitrogen can produce harm to water environment,this article analyzes the in farmland,livestock,human cascade flow law and the characteristics of nitrogen in the system,using time series method to predict the future reactive nitrogen in Yangtze river basin cascade flow water environmental load,The countermeasures to reduce the water environmental load of each system are put forward.In this thesis,the material flow analysis method was used to successfully construct the reactive nitrogen flow model,and comprehensively analyze the nitrogen flow rules and water environmental load changes of agriculture,livestock and human systems in the Yangtze River Basin from 2008 to 2016.The research results are as follows:(1)From 2008 to 2016,the total input of reactive nitrogen from farmland,livestock and human systems in the Yangtze River Basin was increasing,while the output of reactive nitrogen from farmland,livestock and human systems was less than the input,and nitrogen was accumulated into the environment.(2)From 2008 to 2016,the nitrogen use efficiency in the Yangtze River Basin was31%-35% in the farmland system,16.95%-18% in the livestock system,24.5%-22.5%in the human system,and the nitrogen recycling efficiency in the three systems were21%,32% and 60%,respectively.The human system has the highest value of nitrogen use efficiency index,and the water environment loss rate caused by farmland and livestock system is decreasing year by year.The driving factor of the cascade flow of reactive nitrogen is productivity factor.After monte Carlo simulation sampling of the model coefficients,the simulation results are not significantly different from the actual calculated values.In the model,the parameters with extremely sensitive sensitivity were soybean yield,crop sown area and corn yield.The sensitive parameters were nitrogen content of crops and nitrogen content of urine and feces of livestock.Sensitivity grade is general sensitivity parameter is the amount of compound fertilizer.(3)From 2008 to 2016,the nitrogen entering the water environment through runoff from farmland system increased by 9.7%,and the nitrogen entering the water environment through leaching increased by 11.3%.Compared with 2008,the nitrogen load of livestock system in 2016 increased by 12.44%,12.7% and 12.7% respectively through volatilization of manure,runoff of manure and leaching of manure.The change trend of the treated wastewater discharge in human system is generally consistent with that of the human excrement nitrogen after it enters the water environment,which is a decreasing trend in general.From 116,600 tons and 1,133,900 tons in 2008 to 107,500 tons and 719,800 tons in 2016,respectively.After calculating the proportion of nitrogen load of each system into the water environment,it can be seen that the livestock breeding system is the most important source.It is predicted that in 2026,nitrogen into the water environment will reach 22.694 million t N.The management strategy of reactive nitrogen in the Yangtze River Basin is rational diet;Strengthen the utilization of waste,improve the recycling and cascade utilization of waste;Optimize nitrogen use and reduce nitrogen loss.The results of this thesis provide a theoretical basis for the management of water environment nitrogen load in the Yangtze River Basin.