丽娃河受损退化生态系统的近自然恢复工程及效果分析

以丽娃河为例,针对其富营养化现状及河道特征,在传统环境工程治理基础上,构建立体植物群落和动物群落,实施近自然恢复工程,通过比较丽娃河在工程前后的水质和动植物群落的变化来验证近自然恢复工程的效果.研究表明,近自然恢复工程实施一年后,总氮和总磷分别降至0.41mg/L和0.03mg/L;叶绿素a降至7.86μg/L,水质从原来的Ⅴ类降至Ⅱ类标准(GB3838-2002),水质在很大程度上得以改善.除此之外,近自然恢复工程通过直接引入滤食藻类的底栖动物和鲢鱼鳙鱼,在调控藻类生物量的同时也在一定程度上增加了动物群落的生物多样性.实践证明,近自然恢复工程在丽娃河案例中是行之有效的,且耗资少,可以在城市生态系统近自然恢复实践中推广.

Approx-natural ecological restoration engineering and effectiveness analysis of degraded Liwa Creek ecosystems

Based on the eutrophication status and river channel characteristics of Liwa Creek, with the establishment of three dimentional plant communities and animal communities, the approx natrual restoration engineering was carried out after traditional environmental engineering techniques. By comparing the changement of water quality, plant and animal communities in Liwa Creek before and after the engineering, the effects of this approx natural restoration engineering were validated in this paper. The results show that after one year’s approx natural restoration engineering measurement, TN and TP dropped respectively to 0.41 mg/L and 0.03 mg/L; contents of chlorophyll a dropped to 7.86 μg/L; Water quality was improved to a large degree, changing from the original class V to class Ⅱ standard. Besides, with the direct introduction of zoo benthos which filter feeding algae, Silver carp and bighead carp, biodiversity of animal communities is improved to a certain degree during the regulation of algae biomass. Practice proves that approx natural restoration engineering is effective in the case of Liwa Creek based on low cost, which can finally be promoted during the approx natural restoration practice of urban ecosystem.