植物对山地城市雨水花园脱氮除磷效能影响研究

Effects of plants on nitrogen and phosphorus removal efficiency in mountainous urban rain gardens

针对雨水径流中的氮磷污染,采用沟叶结缕草、狗牙根、假俭草、巴哈雀稗、地毯草等5种重庆市常见的本土草本植物,构建雨水花园,通过开展渗透率试验、脱氮试验及除磷试验,考察了这5种植物对初期径流中的氮磷去除效能。结果表明:(1)植被可以有效缓解介质层的堵塞现象;(2)5种草本植物构建的雨水花园均可有效去除雨水径流中的氮素(75%~95%),且干湿条件对植株成熟后的雨水花园脱氮效能影响不大;(3)虽然雨水花园的出水中仍存在较高浓度的总磷,但是出水总磷均为颗粒态磷,其生物可利用性能不高。综合比较,沟叶结缕草和狗牙根组脱氮除磷性能好,植株发育快,可适应不同的干旱湿润条件。

Aiming at reducing the nitrogen and phosphorus pollution brought by rainwater,five native herbaceous plants of Chongqing City,including Zoysia matrella,Cynodon dactylon,Eremochloa ophiuroides,Bahiasgrass,and Axonopus compressus,were selected to investigate the removal efficiency of nitrogen and phosphorus in the initial runoff at rain gardens by leakage rate test and nitrogen and phosphorus removal test.The results showed that plants can ease the blockage in the medium layer.All of the five plants have good nitrogen removal efficiency in the rain gardens(removal rate up to 75%~95%),and the alternating wet and dry conditions have little effect on the denitrification process after the plants became mature.For the phosphorus removal,the discharge water from rain gardens still have high concentration phosphorus,however the form is particulate phosphorus that can hard be utilized by organism.Zoysia matrella and Cynodon dactylon have a good performance in nitrogen and phosphorus removal,and can adapt to the alternating wet and dry conditions.This result can provide technical support for the construction of rain gardens in sponge cities and the theory of nitrogen and phosphorus removal.