不同坡度缓冲带径流污染净化效果及其最佳宽度

Effects of slope and width of riparian buffer strips on runoff purification

在前期资料调研、小试试验和基地选址的基础上，选择百慕大草皮构建了2％、3％、4％和5％四种不同坡度结构的滨岸缓冲带试验基地，开展径流污染物净化效果现场试验。结果表明，坡度与缓冲带径流悬浮固体颗粒物（SS）截留效果显著相关，19m长的2％坡度缓冲带末端的SS截留率达到84％，而5％坡度只有70％；2％坡度缓冲带末端渗流出水总氮（TN）、总磷（TP）平均浓度分别比5％坡度低1．63mg·L^-1和0．1mg·L^-1，在进水TP平均浓度范围为0．9—1．0mg·L^-1时，4种不同坡度试验带的渗流出水TP浓度均低于《地表水环境质量标准》（GB3838-2002）Ⅳ类水标准；通过计算，末端SS去除率为80％时，2％坡度需要的缓冲带最佳宽度为16．1m，5％坡度则为24．7m，两者相差达8．6m。

A series of pilot experiments of runoff pollution purification were conducted on riparian buffer strips covered with Cynodon dactylon at different slopes of 2, 3, 4, and 5%. Results showed that there is a significant relationship between slope gradient and intercept rate of suspended solid （SS） carried by runoff. 84% of SS was trapped on the 19m long strip with the slope of 2%, while 70% of SS removal on the slope of 5%. TN and TP removal rates were higher at the slope of 2% than that at 5%, in which average concentrations of seepage at the slope of 2% were lowed up to 1.63 mg N·L^-1 and 0.1 P mg·L^-1 respectively, while effluent TPs in all experiment treatments were met surface water criteria Class Ⅳ （GB3838-2002） with influent TPs varied from 0.9 - 1.0 mg·L^-1. Results also showed that the optimal strip width was 16. 1m at the slope of 2% , compared to 24.7m at 5%.