基于DO和ORP考量水生植物的生态修复效果

Ecological Restoration Performance of Aquatic Plants Based on DO and ORP Consideration

目前,我国城市黑臭水体整治初见成效,开展水体生态修复成为实现城市水体长制久清目标的重要措施,其中水生植物在提升水体溶解氧(DO)和氧化还原电位(ORP)方面具有重要作用。但在实际工程中,普遍存在对水生植物水体生态修复功能特征不明确、选取盲目性较大等问题,备受推崇的“生态浮岛”难以独立支撑水体修复目标。基于此,以城市水体重要考核指标DO和ORP为研究对象,结合挺水植物、沉水植物、漂浮植物(含“浮岛型”植物)和浮叶植物释放氧气的部位进行特征测试,在自然光条件下观察水体上下层DO和ORP随时间变化的情况。结果表明,沉水植物增氧效果最佳,主要依靠叶片提升水体DO,其余类型水生植物仅通过根部对水体释氧,增氧效果微弱,沉水植物对水体上层DO增幅分别是挺水植物、漂浮植物、“浮岛型”植物和浮叶植物的7.4、4.1、14.8和11.6倍;除“浮岛型”植物外,其余4类水生植物对水体ORP均有较好的保持能力,尤其沉水植物可使水体上层ORP增加约200 mV。综上所述,以DO和ORP为考核指标考察城市水体生态修复时,可以沉水植物为主导,并联用其他类型水生植物。

At present,preliminary progress has been made in the restoration of urban black and odorous water bodies in China.The implementation of water ecological restoration has become an important measure to achieve the goal of long‑term clean‑up of urban water bodies,of which aquatic plants play an important role in improving dissolved oxygen(DO)and oxidation reduction potential(ORP)of water bodies.However,in practical projects,there are widespread problems such as unclear functional characteristics of aquatic plant for ecological restoration and great blindness in plant selection.The highly respected“ecological floating island”is difficult to support the objective of water restoration independently.Based on this,the characteristics of oxygen released from emergent plants,submerged plants,floating plants(including“floating island”plants)and floating‑leaved plants were tested,and the changes of DO and ORP in upper and lower water bodies over time were observed under the condition of natural light.The submerged plants had the best performance of increasing oxygen,mainly relying on leaves to increase the DO in water.By contrast,other aquatic plants only released oxygen to the water through roots,and the oxygen increasing performance was weak.The increase of DO released from submerged plants to the upper water body was 7.4 times,4.1 times,14.8 times and 11.6 times of that of emergent plants,floating plants,“floating island”plants and floating‑leaved plants,respectively.Except for“floating island”plants,the other four aquatic plants all had a good ability to maintain ORP in the water bodies,and the submerged plants in particular increased the ORP in the upper water body by approximately 200 mV.In conclusion,urban water ecological restoration can be carried out by adopting a lot of submerged plants combined with a small amount of other aquatic plants when DO and ORP are used as assessment indicators.