Overview and feature analysis of agricultural non-point source pollution in Guangzhou

In order to understand the characteristics of agricultural non-point source pollution（ANPSP） and make reasonable pollutant control strategies in Guangzhou，taking prefecture city as basic unit，the equivalent standard pollution load method were conducted to the discharge amount and regional difference of chemical oxygen demand（COD），total nitrogen（TN） and total phosphorus（TP） from different types of agricultural non-point source pollutions，including planting，breeding，rural life. And GIS technology was used to assess sensitivity of pollution sources. The results showed that the COD，TN and TP loads of Guangzhou in 2014 were 605 564.60， 21 235.41 and 1 171.60 t，and emission intensities of these pollutants were 814.54，28.56 and 1.58 kg/hm2， respectively. The primary pollution source was livestock breeding whose load ratio in equivalent standard reached 74.37%，and the primary pollutant was COD whose load ratio in equivalent standard reached 52.78%. The highest emission intensity of COD occurred in Huangpu District，the lowest in Liwan District. The highest emission intensity of TN and TP occurred in Tianhe District，the lowerst in Conghua District. The highest sensitive areas and priority control areas were Huadu District，Baiyun District，Huangpu District and Panyu District for the whole Guangzhou.