Source apportionment and spatial heterogeneity of agricultural non-point source pollution in Huangshi, Hubei Province

In order to understand source apportionment and spatial characteristics of agricultural non-point source pollution (NPSP) fully in Huangshi, Hubei, and to further provide evidence to cut it down, the list analysis was conducted to determine the loading of agricultural NPSP in Huangshi. The results showed that the absolute discharge amount of COD, BOD5, total nitrogen (TN) and total phosphorus (TP) from NPSP were 61.2, 35.5, 16.5, 4.3 thousand ton per year, its relevant discharge amount in equivalent standard was 3061, 8874, 16542 and 21726 thousand ton per year. Agriculture NPSP had almost reached water environment capacity and it should be reduced. The main sources of pollution were livestock breeding, chemical fertilizer and domestic sewage and the main pollutants were TN and TP. Discharge concentration of COD, BOD5, TN and TP caused by agriculture NPSP was 26.04, 15.10, 7.04 and 1.85 mg/L, respectively. According to pollution stress, the pollution extent was D