两种漂浮植物的生长特性及其水质净化作用

采用自主研发的漂浮水槽,对两种常用于水体净化与修复的漂浮植物（凤眼莲和水浮莲）在水质净化效果和生长特征等进行了比较研究.结果表明,水浮莲对水体氮磷浓度有更高的要求,对水体中浮游藻类和叶绿素a去除率分别高达94.38%和95.06%,优于凤眼莲;凤眼莲对水体TN的去除率（82.08%）以及其叶片净光合速率（20.28～27.90μmol CO₂/（m²·s））和叶绿素a含量（1.05～1.08mg/g鲜重）均显著高于水浮莲（分别为71.82%、8.64～16.50μmol CO₂/（m²·s）和0.25～0.31mg/g鲜重）（P<0.05）.与凤眼莲共存情况下,水浮莲有更强的扩繁能力,但后者在实际工程应用中更具逃逸风险.为使两种漂浮植物的优势得到充分发挥,我们提出了基于这两种水生植物水体净化的“三明治”模式,为今后选用水生植物进行水体净化与修复的工程实践提供借鉴.

Growth characteristics and water purification of two free-floating macrophytes

Comparative study of the growth characteristics and water purification effects of two free-floating macrophytes, water hyacinth (Eichhornia crassipes) and water lettuce (Pistia stratiotes), on domestic sewage contaminated water had been carried out using self-designed floating sinks. Results showed that the water lettuce has higher requirements on nitrogen and phosphorus concentrations, and the removal rates of phytoplankton and chlorophyll a by the water lettuce were respectively reached to 94.38% and 95.06%, which were significantly higher than those by the water hyacinth. The TN removal rate (82.08%), the net photosynthetic rate (27.90~20.28 μmol CO₂/(m^-2·s)), and the chlorophyll a content (1.05~1.08mg/g fresh weight) of the water hyacinth were respectively higher than those (they were 71.82%, 8.64~16.50 μmol CO₂/(m²·s) and 0.25~0.31mg/g fresh weight, respectively) of the water lettuce (P<0.05). However, when cultivated together with the water hyacinth, the water lettuce has higher reproductive ability and may have the risk of escape in engineering practice. In order to take full advantage of these two free-floating macrophytes in terms of water purification, a "sandwich" pattern for their cultivation was proposed. The results of this study would provide practical and theoretical references for the use of aquatic macrophytes for water purification and restoration in engineering practice.