Testing of winter vegetation construction and water purification effect of a cascaded wetland model of Jialu river

In order to test the winter vegetation construction and water purification of wetland in vast northern China, a cascaded surface-flow wetland model with a total area of 7400m² was constructed along the Jialu river floodplain in Zhengzhou city of Henan province. After winter vegetation such as Potamogeton crispus, Elodea Canadensis and Iris. Sibirica were planted, vegetation development and purification effect was observed continuously. Results show that Potamogeton crispus and Elodea Canadensis survived under very low temperature and the vegetation coverage stood at 50percent, Siberian Iris all survived and issued new leaves. Water purification effect indicates that the average removal rates of nitrogen, phosphorus ammonia and COD_Cr were 32%, 67%, 55% and 29% respectively with hydraulic loading of 140mm·d^-1, and the purification efficiency can be strengthened with gradual development of the vegetation. This study demonstrated that wetland with reasonable winter aquatic plants and species composition can ultimately improve the purification effects of wetlands in north China. In addition, waste heat in urban drainage can provide favorable conditions for winter vegetation in cascaded wetland, so it is feasible to increase appropriate water depth to built submerged vegetation with Potamogeton crispus and Elodea Canadensis.