Situation And Control Effect Of Agricultural Non-point Source Pollution In Typical Small Watershed Of Fengle River

In recent years,the non-point source pollution caused by unreasonable production and lifestyle in agriculture and rural areas has become increasingly serious,and has gradually become an important cause of environmental deterioration in rural areas.Treatment of non-point source pollution in small watershed has gradually become an important measure to control non-point source pollution in agriculture.According to the sources and characteristics of agricultural non-point source pollution,the evaluation of the current situation of agricultural non-point source pollution in small watershed and the comprehensive treatment research are helpful to improve the social,economic and ecological benefits of the watershed.This study for Shucheng Fengle river watershed agricultural non-point source pollution present situation and the characteristic has carried on the investigation and analysis,using the questionnaire investigation in the typical small watershed area of Fengle river field research,and using standard pollution load method in the basin area such as peach brook town and one thousand bridge town agricultural pollution,livestock and poultry breeding pollution,pollution comprehensive analysis and rural life.The small watershed by implementing agricultural non-point source pollution control engineering,livestock and poultry breeding pollution control engineering,surface runoff sewage purification and utilization of engineering,establishing typical watershed agricultural non-point source pollution comprehensive demonstration area,promote agricultural virtuous cycle and in small watershed agricultural non-point source pollution emission reduction.This study further evaluated the implementation effect of the pilot project of comprehensive prevention and control of agricultural non-point source pollution in Shucheng county by monitoring the water quality of ditches and rivers before and after the treatment of this small watershed.The main research conclusions are as follows:（1）In a typical small watershed of Fengle river,the average fertilizer use amount of planting industry reaches 475kg/hm²,which is twice the safety level recommended by developed countries（225kg/hm²）.The resulting non-point source pollutants（TN,TP,COD）are up to 45.77t,of which TN is 44.21t,accoVuIInting for 96.58%of the total loss.The total amount of TN,TP and COD pollutants discharged by livestock and poultry breeding industry is 26.59t.Because there are more duck farms in Qianrenqiao town,the pollution load rate of breeding industry is higher,accounting for 83.73%of the total pollutants.The proportion of COD was the highest in rural pollution,accounting for 90.93%.The second is TN,accounting for 7.73%.TP was the lowest,accounting for 1.34%.（2）In the typical small watershed of Fengle river,the non-point source pollution discharge and pollution load rate are the highest in rural non-point source pollution.The total TN,TP and COD emissions reach 138.14t,and the pollution load rate is 65.62%.The pollution load rate of planting industry was 21.74%,and the total pollutant emission of TN and TP was 45.77t.The lowest pollution load ratio of aquaculture was 12.63%,and the total TN,TP and COD emissions were 26.59t.（3）Among the three evaluation factors of TN,TP and COD,COD has the highest pollution load rate,which is 68%.The second is TN,with a pollution load rate of 29.58%.TP pollution load rate is 2.42%.（4）The results of monitoring the water quality of farmland,rivers,livestock and poultry breeding sewage and domestic sewage showed that the water quality of Fengle river typical small watershed was obviously improved by implementing farmland non-point source pollution prevention project,livestock and poultry breeding pollution treatment project,surface runoff sewage purification and utilization project and other measures.Governance former farmland,rivers,livestock and poultry breeding waste water and sewage water quality indicators in line with the average concentrationⅤclass water standard;After treatment,the water quality standards for the average concentration of total nitrogen,total phosphorus,ammonia nitrogen and COD in farmland drainage were all raised to one level;the water quality standards for the average concentration of ammonia nitrogen,COD and BOD₅in river monitoring were all raised to one level;and the water quality standards for the average concentration of total phosphorus were raised to two levels.Rivers and farmland drainage the overall concentration of the ammonia nitrogen and total phosphorus in appeared a downward trend,rivers and the drainage of ammonia nitrogen and total phosphorus concentration analysis conform toⅢclasses andⅢmore kinds of November 6,2019-about 50%to the total number of sampling,river monitoring,suspended solids and fecal e.group of bacteria number decreased significantly;The improvement of river water quality is more obvious than that of farmland drainage water quality.But in farmland fertilization time,rivers and fields of total nitrogen,total phosphorus,ammonia nitrogen and chemical oxygen demand（cod）concentration increased significantly,achieveⅤclass standard.The comprehensive control measures of environmental pollution in this small watershed enable all the sewage of livestock and poultry breeding and living to reach the standard of discharge,and the whole water body is upgraded to a higher level,which significantly reduces the discharge of pollutants in the watershed and obviously promotes the improvement of water quality in the watershed.However,the pollutants from planting industry also have some environmental risks to the water quality of the river basin.（5）In the governance of small watershed,the treatment effect of life pollution sources and livestock and poultry pollution sources is easy to be obvious in a short time,while the short-term treatment effect of planting pollution sources is not obvious.This indicates that more attention should be paid to the governance of planting pollution sources in the governance of small watershed agricultural non-point source pollution sources.