水生高等植物对悬浮泥沙的去除研究

REMOVING SUSPENDED SEDIMENT WITH AQUATIC MARCROPHYTES

根据自然水体湿生植物(挺水植物)、浮叶植物以及沉水植物的空间分布规律,利用风车草(Cyperus alterni-folius)、石菖蒲(Acorus tatarinowii)、菱(Trapa japonica)、金鱼藻(Ceratophyllum demersum)、轮叶黑藻(Hydrillaverticillata)和苦草(Vallisneria spiralis)等水生植物构建由挺水植物、浮叶植物到沉水植物的串联系统,含沙水依次流经挺水植物、浮叶植物和沉水植物,测定各级植物对泥沙的去除效果。结果显示,输入悬浮泥沙浓度依次为21.76、37.04、45.097、1.18 mg/L,水力停留时间(HRT)分别为12、16、24、24 h,水生高等植物串联系统对悬浮泥沙的去除率分别为68.1%、71.7%、77.5%、74.0%,表明水生高等植物可有效去除水体中的悬浮泥沙,改善了透明度。水力滞留时间对植物去除悬浮泥沙的效果有较大的影响,水力滞留时间长,即使输入悬浮泥沙浓度很高,去除率和单位时间的净去除量也较高;浅水区的挺水植物对进水高浓度悬浮泥沙的有效过滤作用减缓了悬浮泥沙对深水区沉水植物的胁迫压力;沉水植物能进一步去除悬浮泥沙,抑制再悬浮作用,对水生生态系统的稳定有十分重要的作用。

In order to remove different concentrations of suspended sediment （SS）, a serial connected system of emerging plants, floating-leaved plants and submerged plants based on spatial distribution of natural water body was constructed by aquatic marcrophytes, such as Cyperus alternifolius, Acorus tatarinowii , Trapa japonica, Ceratoph yllurn dernersurn , Hydrilla verticillata and Vallisneria spiralis. Sandy water then flew through emerging plants, floating-leaved plants and submerged plants. The input SS concentrations were 21.76, 37.04, 45.09 and 71.18 mg/L, and the hydraulic retention time （HRT） of each concentration were 12, 16, 24 and 24 h. The removal rates of SS were 68. 1%, 71. 7%, 77. 5% and 74.0%. The aquatic marcrophytes not only removed the SS, but also greatly improved the transparency of water. The HRT obviously influenced the removal effect. While the HRT was long, no matter how high was the input SS concentration, the removal rate and the net removal per unit time could achieve an ideal level. Placing emerging plants in the region with higher input SS concentration could reduce the SS concentration, and palliate the environmental press of deep water area on submerged plants. Therefore, submerged plants were necessary for the stabilization of the whole ecosystem, which further removed the SS that might not be cleaned by emerging plants, and the resuspension of SS was restrained.