Evaluation of agricultural non-point source pollution and countermeasures in Shuikou Reservoir Drainage Area

Agricultural non-point sources pollution (including living contaminants, human feces and urine, rural solid trash and living rubbish, chemical fertilizer, livestock and bird aquatics, farm nutrient loss, surface runoff from villages and small towns, aquiculture, etc.) in 18 townships in Shuikou Reservoir Drainage Area were surveyed and evaluated by equivalent standard discharge amount method. The results show that the total discharge of CODcr, TN and TP are 6 288.87 ton, 4 450.07 ton and 1 448.82 ton respectively, with a total equivalent standard discharge of 1.936×10¹⁰m³. The pollution rate index of CODcr, TN and TP is 2.17%, 22.99% and 74.85%, respectively. Therefore, N and P are the primary contaminants in the drainage area. Furthermore, the largest three pollution rate indexes for the pollution sources are farm nutrient loss, aquiculture, livestock and bird feces & urine, with percentages of 41.95%, 36.81% and 10.60% respectively. The cumulative pollution rate index of the three pollution sources is 89.36%, hence they constitute the primary pollution sources in the area. Among the 18 villages and townships surveyed, the total equivalent standard discharge of Huangtian in 2005 is 2.942×10⁹m³, with a pollution rate index of 15.20%, the largest in the basin. Those of Shuikou and Dongqiao are the second and third, in that order. The results also indicate that different villages and townships have different primary pollution sources. For example, living sewage is the leading pollution source in Huangdun and Shuidong, livestock and bird feces & urine is the leading one in Luxia and Dahuang, farm nutrient loss in Meixi and Dongqiao, and aquiculture leads the rating for Shuikou and Youxikou. Therefore, different villages and townships should take varying measures to address agricultural non-point source pollution. Finally, advanced prevention, remediation and other countermeasures to agricultural non-point source pollution in Shuikou Reservoir Drainage Area include improving agricultural legislation and intensifying management measures, strengthening research and technology devoted primarily to agricultural chemical substances, developing all-purpose and comprehensive use of dejecta of livestock and birds, developing ecological and organic agriculture, advocating cleansing production and enhancing rational application of fish feed and medication to reduce losses.