Pollutant Accounting and Source Analyses in the Yangtze River Basin

The output process of pollutants in the Yangtze River basin was studied using a model including five processes for the pollutants,generation,emission,pouring into the river,degradation and output.The Yangtze River basin was divided into 114 units and 195 reaches in this study in order to investigate the temporal and special change of the pollutants in this area.According to the data on socio-economic and hydrological conditions of four monthly monitoring sites from 2004 to 2007,the pollutant output process of each reach of the Yangtze River basin was calculated through output balance analysis.The pollutant output process of the section of Yaogang at the Yangtze River estuary,was further estimated.The differences between the estimated and investigated values were less than 20%.Simulation results showed that the CODMn flux was mainly impacted by the point source pollution which accounted for 56.4%,and fluxes of the total nitrogen(TN) and the total phosphorus(TP) were mainly impacted by the non-point source pollution which accounted for 74.3% and 92.1% respectively.Four provinces,Jiangxi,Sichuan,Hunan and Hubei were the key areas of pollution control of the river basin,since they contributed more than 60% of the total pollutant output loads of the whole river basin.