An Investigation Into The Purfication Effect Of Aquatic Plants On Landscape Waters

With the continuously rapid social development, landscape waters have been widely applied to urban construction in recent years. How to guarantee the quality of the landscape waters becomes a crucial issue. This study investigated and analyzed the landscape waters of several residence communities. An experiment was carried out to examine the purification effect of several kinds of common aquatic plants on the eutrophic waters.(1)The author did field research on the landscape waters of 20 residence communities in Changsha. I found that about 72% landscape waters are eutrophic. The main reasons are as follows:the stereoplasm of the revetment and the bottom of the pool, the inappropriate application of the aquatic plants and the problems in maintenance management of the waters. Then the paper gives some suggestions on the application of the aquatic plants in the landscape waters.(2) Five common aquatic plants are selected for the experiment of comparing the purification effect on eutrophic waters, namely, grassleaf sweelflag rhizome, purple lythrum herb, water arum, water lily and hydrilla verticillata. After 15 days of purification, the order of the absorption rates of TP by the five aquatic plants is Calla palustris 98.2%>Acorus tatarinowii 93.3%>Lythrum salicaria 75%>Hydrilla verticillata 35.7%>Nymphaea tetragona 16.5%;the order of absorption rates of TN by the five aquatic plants is Calla palustris 70.2%>Lythrum salicaria 70.1%> Acorus tatarinowii 69.4%>Hydrilla verticillata 65.8%>Nymphaea tetragona 57.4%; the order of the COD removal rates of the five aquatic plants is Acorus tatarinowii 57.3%>Calla palustris 56.3%>Lythrum salicaria 52.2%>Nymphaea tetragona 49.8%>Hydrilla verticillata 48.8; the order of the BOD5 removal rates of the five aquatic plants is Acorus tatarinowii 61.1%>Hydrilla verticillata 59.3%>Lythrum salicaria 58.9%>Nymphaea tetragona 57.9%>Calla palustris 57.8%;the order of the amount of DO conditioned by the five aquatic plants is Nymphaea tetragona> Lythrum salicaria>Calla palustris>Hydrilla verticillata>Acorus tatarinowii. During the experiment, each kind of plants can keep the pH value of the water at 6.5-7.5.The data on every aspect of the waters meet the standard on the quality of landscape waters. This study verified that the aquatic plants can purify the eutrophic waters to a large extent.