Load estimation of agricultural non-point source pollution in source area of Liaohe River

Non-point source pollution has became a major source of water body pollution in China in recent years,in which the largest contribution is agricultural non-point source pollution. In order to explore agricultural non-point source pollution levels of the source area of Liaohe River,the paper used pollutant emission coefficient to estimate non-point source pollution load in the area from 1999 to 2009and analyze the variation trend of COD,TN,TP and ammonium nitrogen pollution load. The equivalent standard pollution load method was applied to evaluate agricultural non-point source pollution status. The results showed that the total export of chemical oxygen demand( COD),total nitrogen( TN),total phosphorus( TP) and ammonium nitrogen( NH 3-N) were 35899. 67,10402. 40,1258. 56 and 4306. 22 tons per year from 1999 to 2009 in the source area of Liaohe River watershed,respectively. Among all different pollutants,TN is the major pollutants of non-point source pollution in the source area of Liaohe River watershed,which accounts for 47. 21% of all pollutants. Among all different sources,the pollution load ratio of livestock and poultry breeding is 70. 56% witch is far more than the sum of the other three types of non-point source pollution load. Livestock pollution is the main source of non-point source pollution in Liaohe River basin. The ratio of rural life source pollution load is 19. 33% which is higher than the farming and aquaculture. By comparison of different areas,the non-point source pollution load of Lishu,Gongzhuling,Dongliao and Shuangliao is greater than that of other areas and the four cities / counties are the major pollution areas.