Clarification efficiency of vegetative filter strips to several pollutants in surface runoff

Vegetative filter strip (VFS) is a main kind of Best Management Practices for the control of non-point pollution. For investigating the practical use of VFS in Chinese northwest, three VFSs with different vegetation planting patterns have been constructed in the bank slop of Xiaohuashan Reservoir, Huaxian County, Shanxi Province. Clarification effects of VFSs to pollutants in surface runoff and influencing factors have been analyzed based on the measured data of plot experiments. Results show that the concentration reduction rate of particulate N, particulate P, total N, total P and COD in surface runoff by VFS reached 82.0%, 77.13%, 46.05%, 73.28% and 60.48%, respectively, under the test conditions; and load reduction rate for these pollutants achieved 89.98%, 87.25%, 69.93%, 85.11% and 77.97%, respectively; In addition, the load of dissolved N and dissolved P could be decreased effectively. The experiment also shows that the most pollutants were entrapped in the first 10 m of the grassed strip and the Hippophae rhamnoides sub.sinensis/grass strips. The main factors influencing clarification efficiency of VFS include vegetation conditions, inflow rate and inflow pollutant concentration.