Analysis Of Non-point Source Pollution Load And Distribution Of Agricultural Fertilizers In Danjiangkou Reservoir Area

Researching the agricultural fertilizer pollution load and spatial distribution characteristics in Danjiangkou reservoir area is of great value for the scientific formulation of response measures.this paper used the fertilizer pollution environmental risk assessment model to analyze and evaluate the spatiotemporal variation and environmental risk of chemical fertilizer application in reservoir area based on the field investigation and yearbook data of the fertilizers application amount and cultivated land areas from 2002 to2014 at 8 counties of Danjiangkou Reservoir.The concentration of COD,TN,TP and NH3-N in the adjacent farmland in the reservoir area was detected.The graded color representation method of ArcGIS software was used to classify the amount of chemical fertilizer applied,the load of fertilizer application,the risk level and the water pollutant content in different colors that different levels.Clearly reflect the spatial distribution and change characteristics,we can visually see the most polluted areas and the severity of each area,so as to conduct more detailed evaluation and analysis.In addition,the field investigation of farmers'cognition and behavior on non-point source pollution of agricultural chemical fertilizers was conducted to understand the influencing factors so as to control the deterioration of agricultural non-point source pollution more effectively.The main results of this paper are as follows:?1?the total amount of fertilizer application and the fertilizer load per unit area increased year by year in the reservoir area from 2000 to 2014.Among them,the application amount of fertilizer in Dengzhou county accounted for the largest proportion of the total fertilizers,nitrogen fertilizers and phosphate fertilizers in the reservoir area.The fertilizer load of Xiaxian County,Yunxi County and Shiyan county were at a high level,Neixiang county at the lowest level.?2?The overall risk level of fertilizer application was at the middle risk level in the reservoir area from 2000 to 2014.In 2014,the risk level of total fertilizers,nitrogen fertilizers and phosphate fertilizers in the reservoir area was in the middle risk.The risk level in Danjiangkou county was the lowest risk.The risk level of Shiyan county was the highest in total fertilizer and nitrogen fertilizer,and the risk level of Xixia county was the highest in phosphate fertilizer in the total area.?3?By sampling and testing the water quality in the reservoir area,it was found that the water pollutant concentration in dry season was generally higher than that in wet season.Overall,the high water pollutants areas were mainly concentrated in Xichuan county?Xixia county and Yun county.The pollutant concentrations in the inbound rivers were higher than those in the reservoir area.?4?There was a significant correlation between TN,TP,NH₃-N and COD concentrations in water quality and fertilizer application load.The correlation coefficient between annual average concentration of TN and NH₃-N and fertilizer loading was 0.998,which was extremely significant at 0.01 level.The average concentrations of TP and COD were significantly correlated with the fertilizer loading at 0.05 level.?5?According to the investigation and analysis of farmers?cognition and behavior of fertilizer non-point source pollution in Danjiangkou reservoir area,most farmers know some of fertilizer non-point source pollution,but their understanding is not correct and comprehensive enough and few farmers will take practical actions to prevent fertilizer non-point source pollution.The educational level of farmer households have significant correlations with farmers'cognition and behavior,which were important factors to improve farmer's cognition and behavior.