不同水生植物在暴雨湿地中的水质净化作用

选择菖蒲、芦苇、美人蕉、鸢尾和水花生(空心莲子草)5种典型的湿地水生植物,以武汉动物园猩猩馆流域为研究区域,通过三年的长期定位试验,研究了这5种典型水生植物对暴雨径流湿地中氮、磷等不同污染物的吸收能力、养分负荷变化、吸附解析性能以及去除贡献率。结果表明,水生植物对氮、磷的吸附能力主要与水生植物的生物量有关,随着生物量的增加逐渐升高。在降雨量逐渐减少的情况下,植物体吸收的氮磷占流域年输入总氮的百分比可以从7.8%升高到35.9%,占流域输入总磷的百分比从21.8%升高到69.4%。在这5种典型水生植物中,芦苇对湿地中氮的吸收能力最强,鸢尾对湿地中磷的吸收能力最强;芦苇和菖蒲茎叶中的氮、磷、钾元素含量要高于根系中的养分含量;不同的植物种类在腐烂时污染物的释放量差异较大,其中鸢尾释放量最大,其次是菖蒲和美人蕉,芦苇释放量最少;而菖蒲对水中高锰酸盐指数和TP的吸附量最大,其次是鸢尾、美人蕉和芦苇。

Comparative Study on Different Aquatic Plants' Roles in Purification of Storm Runoff by Wetlands

Five different aquatic plants of a wetland system in Wuhan Zoo were studied with respect to their abilities of absorption of nutrients, nutrient loading and the adsorption/desorption. The investigation concerned showed that the sorption capability of the plants depended on their bio-mass, and that among the five species of plants Phragmites comunis Trin was the best in absorbing nitrogen while Iris tectorum, the best in phosphorus absorption in the wetlands. It has been also found that concentrations of nutrients such as N, P and K were higher in stems and leaves than in roots in the case of Phragmites comunis Trin and Acorus calamus Linn; and Iris tectoru released the most of the nutrients when decaying in the wetlands, meanwhile Acorus calamus Linn excelled in removing COD_(Mn) and TP from water.