Investigation And Evaluation Of Agricultural Non-point Source Pollution In Zhongxing Reservoir Small Watershed In Upper Reaches Of Chaohu Watershed

As the non-point source pollution in the watershed is becoming more and more serious,it poses a serious threat to the safety of water bodies in the basin.As a result,the control of non-point source pollution in the watershed has become a major problem in controlling agricultural non-point source pollution and controlling soil and water loss Important way Agricultural non-point source pollution,as a dissolved or solid pollutant in agricultural production activities,enters the water body from non-specified areas and causes water body pollution due to precipitation and runoff scouring.According to the sources and characteristics of agricultural non-point source pollution in small watershed,the study on the status quo and comprehensive management of agricultural non-point source pollution in small watersheds is beneficial to improve the ecological benefits,economic benefits and social benefits.In this study,we conducted a field survey in the watersheds of Zhongxing Reservoir in Chaohu Lake Basin through questionnaire survey.We conducted a survey on the cultivation,breeding and human-caused non-point source pollution in the three villages around Zhennan,Tongxin and Changwang in the reservoir area.Accounting analysis.This paper evaluates the influence degree of various agricultural factors on the surface water pollution in the small watershed by using the equivalent standard pollution load method to understand the status quo and characteristics of the agricultural non-point source pollution in this area and provides a reference for the formulation of targeted prevention and control measures.Through agricultural non-point source pollution prevention and control projects,livestock and poultry breeding pollution control projects,surface runoff sewage purification project,the beautiful rural sewage treatment facilities and environmentally friendly agricultural measures to promote.To establish an agricultural demonstration zone that combines the control of agricultural non-point source pollution in typical river basins with the improvement of overall agricultural benefits,and promote the virtuous cycle of agriculture and reduction of agricultural non-point source pollution in small watersheds.The main findings are as follows:(1)There is excessive use of chemical fertilizer in crop cultivation in small watershed,unreasonable fertilization structure,and the use of chemical fertilizer is above 530 kg / hm2,which is significantly higher than the recognized safety level of 225 kg / hm2 in developed countries.The total amount of TN and TP pollutants released into the water from plantation fertilizer sources totaled 25.52 t,mainly TN,reaching 25.24 t,accounting for 98.92% of the total loss from planting sources.(2)The pollution sources of aquaculture in three communities in Zhongxing Reservoir are 109.00 t in total.The main pollutants are COD,the pollution load rate of Zhongwang Wangzhong in livestock and poultry breeding industry accounts for the total amount of pollutants in breeding sources Of the 82.14%,mainly due to the modern animal husbandry factory is located in Changwang community,more serious pollution.In Zhennan community,more live chickens were found,which accounted for 17.54% of the total pollution load of breeding farms,and 0.32% of Tonghe communities had lower pollution load of breeding sources.(3)The non-point pollution caused by human living in three communities in Zhongxing Reservoir watershed project area is dominated by COD,accounting for 96.45% of the total discharge of pollutants;followed by TN accounting for 3.06%;TP is the lowest,accounting for 0.49%.(4)Among the sources of agricultural non-point source pollution,the total amount of non-point source pollutants brought by crop fertilizers reached 25.52 tons and the load rate was 13.47%.The pollutant discharge and the pollution load rate of the pollution source of aquaculture are the largest,with the discharge of pollutants reaching 109.00 t and the maximum of 57.52% of the sewage discharge rate,mainly taking COD emissions as the main emission,reaching 90.38 tons.The pollutants produced and produced by residents accounted for 29.01% of the non-point source pollution load in small watershed,the total amount of pollutants reached 54.97 tons,and the pollution source of non-point source pollution in small watershed was 29.01%.(5)Among the three evaluation factors of COD,TN and TP,the COD pollution loading rate was the highest,reaching 74.26%;the TN pollution loading rate was 21.13%;the TP pollution loading rate was 4.61%.(6)The results of soil testing and analysis of precise fertilization soil testing showed that available potassium and slow-acting potassium were abundant in the project area,available boron and available manganese were concentrated at medium level,and other nutrient contents were deficient and deficient.Low overall fertility.(7)Through the monitoring results of farmland and river water quality,the total nitrogen,total phosphorus,and chemical oxygen demand are relatively high.Especially during farmland fertilization,total nitrogen,total phosphorus,and chemical oxygen demand in farmland discharge water bodies and rivers With higher values,the discharged water has reached Class V water quality,and there is a certain risk of environmental pollution to the drinking water source of the downstream Zhongxing Reservoir.