Spatiotemporal Analysis Of Agricultural Non-point Source Pollution In Jiangxi Province Based On Improved Output Coefficient Model

Due to its universality,randomness,and other characteristics,non-point source pollution has become an obstacle to the rapid development of today’s society,posing a serious threat to people’s lives and health.Agricultural non-point source pollution is its most important component.Jiangxi Province has developed water systems and undulating terrain,with a relatively high proportion of rural agricultural population in the province.At the same time,the Poyang Lake Plain in the north is one of the nine major grain production bases in China.But at the same time,the problem of non-point source pollution in agricultural production is also becoming increasingly serious,which has a serious impact on the water system in Jiangxi Province,especially Poyang Lake.Therefore,exploring the spatiotemporal distribution pattern of non-point source pollution in Jiangxi Province,identifying the main pollution patterns and areas,hoping to provide certain scientific reference opinions for water ecological protection and nonpoint source pollution control in Jiangxi Province.This article takes Jiangxi Province as the research area,takes 100 counties and districts within the province as the research object,uses software such as Arc GIS,Origin,SPSS,and relies on meteorological data,topographic data,and regional related statistical data to divide farmland planting patterns in Jiangxi Province.By assigning different pollution coefficients to different planting patterns,the pollution coefficients of the province’s farmland are spatialized,and the calculation of farmland non-point source pollution load is optimized;At the same time,the river inflow coefficient is introduced to improve the classical output coefficient model,transforming the original pollution load generation amount into the pollution load inflow amount;The agricultural non-point source pollution load in Jiangxi Province during the period from2010 to 2020 was calculated and analyzed in order to identify the agricultural heavily polluted areas and their main pollution types in Jiangxi Province,and propose corresponding treatment methods.The main research results are as follows:(1)Considering that the surface source pollution load is influenced by rainfall scouring and vegetation retention during the process from generation to entry into water bodies,the improved output coefficient model was constructed by introducing various influence factors on the basis of the original output coefficient method,and the improved output coefficient model was used to calculate the agricultural nitrogen and phosphorus pollution load in Jiangxi Province,and the errors were found to be below5% after calibration,indicating that the improved output coefficient model is feasible in the region of Jiangxi Province.(2)The pollutant loads of four main agricultural pollution modes in Jiangxi Province during the period 2010 to 2020 were calculated and analyzed.The results showed that during the past 11 years,the agricultural nitrogen and phosphorus nonpoint source pollution load in Jiangxi Province showed a trend of first increasing and then decreasing,with the overall nitrogen and phosphorus pollution load in planting,aquaculture,and rural life showing a downward trend,while the fishery pollution load showed a slight upward trend;In terms of pollution contribution rate,the pollution contribution rate of livestock and poultry breeding industry and rural life has remained basically unchanged,while the pollution contribution rate of planting industry has shown a rapid downward trend,while the pollution contribution rate of aquaculture industry has increased rapidly,which deserves attention.(3)Analysis of main pollution modes.Taking 2020 as an example,the contribution rate of total nitrogen in the four main pollution modes from high to low is as follows:livestock and poultry breeding>farmland planting>rural life>aquaculture;The contribution rate of total phosphorus from high to low is as follows: livestock and poultry breeding>farmland planting>aquaculture>rural life.It can be seen that aquaculture and planting are the main sources of nitrogen and phosphorus load from agricultural non-point source pollution in Jiangxi Province;Further analysis of the planting and aquaculture industries found that among the 29 planting patterns in farmland in Jiangxi Province,the main sources of total nitrogen pollution were "gentle slope paddy fields" and "flat land paddy fields",while the main sources of total phosphorus pollution were "flat land dry land vegetables" planting patterns;In the aquaculture industry,poultry farming is the main source of total nitrogen pollution in the aquaculture industry,while total phosphorus pollution in the aquaculture industry is mainly contributed by pig farming.(4)Identification of main pollution areas.The spatial distribution of agricultural surface source pollution in Jiangxi Province generally shows the distribution characteristics of high in the middle and low around,and the areas with high intensity of agricultural surface source pollution emission are mainly concentrated in most areas of Nanchang City and northeast of Yichun City.After studying the main pollution patterns for the region,it was found that among the 100 counties(districts)in Jiangxi Province,the regional agricultural pollution load mainly originates from farming-type pollution and mixed-type pollution,while the remaining types,such as planting-type pollution,are more scattered and fishery-type pollution is mainly distributed in some areas in northern Jiangxi Province.