冬季水生高等植物对富营养化湖水的净化作用

The purification ability of aquatic macrophytes for eutrophic lake water in winter

在太湖－湖湾的物理－生态工程围区内，采用覆膜和改变生态位的越冬技术，使喜旱莲子草，凤眼莲等漂浮植物能安全越冬，并有效地改善水体透明度，为水植物生长及种群自我演替提供了保障，静态试验结果表明，采取简易的防寒越冬技术，改变生态位的喜旱莲子草对ＴＮ，ＮＨ＾＋４－Ｎ，Ｃｈｌａ的去除率达７７．２％，９０．１５，５８．３％透明度提高１．５倍；对喜旱莲子草覆膜并间种沉水植物，这一镶嵌组合群落对ＴＮ，ＮＨ＾＋４－

In the enclosures of physical-ecological engineering, floating-plants,such as water peanut and hyacinth,can livethrough the winter with some overwintering techniques. These techniques include covering floating-plants with plasticfilm, changing the niche of floating-plants and rehabilitating the mosaic community of macrophytes (MCM). The ovenwintering water-peanut, Alternanthera philoxeroides Griseb, improves the transparency of the eutrophic lake waterTherefore, the submerged plants can survive in the winter. The removal efficiencies of submersed water-peanut for TN,NH4-N and Chla are 77.2%, 90. 1% and 58.3% in winter, respectively. The transparency in the enclosure of submersedwater-peanut is 1.5 times higher than that in the outside of enclosure. The removal efficiencies of MCM covered withplastic film for TN, NH4-N and Chla are 65.7%,90.7% and 58.7% in winter,respectively.The transparency is heightened1.6 times by MCM in winter.The results of dynamic experiment show that when the retention time of the eutrophic lakewater is 7.33 d in the MCM enclosure, the overwintering MCM can increase the transparency by 2.6-3.0 times(up to90~100cm). The concentrations of TN, TP and NH+-N, decrease by 37.5%,52.0% and 75.4%,respectively. However,when the retention time is shorter than 4.33 d, the purification efficiencies are insignificant.