Source Analysis And Regulation Simulation Of Non-point Source Nitrogen And Phosphorus Pollution In Nansi Lake Basin

Non-point source pollution,also known as non-point source pollution,especially agricultural non-point source pollution,is the biggest factor affecting water quality,and is also a world problem that is difficult to control.Non-point source nitrogen and phosphorus pollution in the Nansi Lake Basin is the main factor affecting the water quality of the South Fourth Lake and the South-to-North Water Transfer Project.It identifies the source of non-point source nitrogen and phosphorus pollution in the Nansi Lake Basin and its main influencing factors,and adopts reasonable and effective regulation.The simulation measures are of decisive significance for the success of water resources management in the basin and the east route of the South-to-North Water Transfer Project.This thesis establishes a non-point source pollution classification method based on hydrology and water quality data,analyzes the temporal and spatial evolution characteristics of non-point source pollution in the Nansi Lake watershed,and improves the export coefficient model by considering the pollutant migration and dissolution process,which is not for the Nansi Lake Basin.The sources of point source nitrogen and phosphorus pollution were quantitatively analyzed,and the non-point source pollution reduction effects and required costs of the control measures under different combinations were simulated and optimized.Through research,the following conclusions are drawn:(1)Non-point source pollution of nitrogen and phosphorus has become the main source of water pollution in the Nansi Lake Basin.The proportion of non-point source pollution of nitrogen and phosphorus in the Nansi Lake Lake Basin is 65.9% and 66.8%,respectively.The contribution rates of non-point source total nitrogen pollution in Zaozhuang City,Heze City,Jining City and Taian City were 14.7%,35.8%,45.4% and 4.1%,respectively.The contribution rate of non-point source total phosphorus pollution was 14.5% and 37.6%,43.8% and 4.1%.(2)Based on the improved export coefficient method,the sources of non-point source nitrogen and phosphorus pollution were analyzed.The proportions of non-point source total nitrogen pollution in land use,livestock breeding and rural life were 33.6%,25.9% and 40.5%,respectively.The proportion of total phosphorus pollution was 31.6%,43.7% and 24.7%.In the analysis of sources of different land use types,the proportion of dry land contribution was 81.3% and 81.9%,respectively.Based on statistical analysis of quantitative analysis of non-point source pollution influencing factors,the main factors of non-point source total nitrogen pollution are annual cattle breeding and annual runoff,the relative contribution rate is 23.57% and 7.52%;the main factor of total phosphorus pollution is annual cattle breeding.At the end of the year,the agricultural population and annual pesticide volume,the relative contribution rate was 39.75%?14.10% and 8.07%;the main inhibitors of non-point source total nitrogen pollution are construction land area,gross domestic product and total population at the end of the year.The relative contribution rates are 35.21%,21.25% and 9.71%.The total phosphorus inhibition factors are construction land area and GDP.The relative contribution rate was 19.19% and 17.57%.(3)By means of restoration of protection costs,opportunity cost and other methods,9 kinds of control measures such as conservation tillage of cultivated land below 6°,high plant hedgerows such as 6-15° planting,and vegetation buffer zone + no-tillage of livestock and poultry free-range household biogas tanks were simulated.The scenario found that the biogas digesters of livestock and poultry,the conservation tillage of cultivated land below 6°,and the non-point source nitrogen and phosphorus pollution load reduction effect of no-tillage were better,and the total nitrogen reduction was 8133.02 t,7642.24 t and 4709.75t;total phosphorus reductions were 1344.41 t,1170.72 t and 2341.45 t,respectively.The economic benefits in the regulation scenario are better soil testing and fertilization techniques and conservation tillage of cultivated land below 6°,respectively,which are 37.39 million yuan and 54.83 million yuan.(4)Through the comprehensive evaluation of pollution reduction effect and economic benefits,this paper first recommends the technical measures of promoting cultivated land conservation tillage and soil testing formula fertilization,followed by livestock and poultry retail farmers biogas digester.In addition,the cost of “coastal vegetation buffer zone + notillage”is lower,the environmental benefits are more significant,and the cost of operation and maintenance is low,which is also worth recommending.