Study On Water Improvement Effect On Polluted Water By Submerged Macrophytes

Submerged macrophytes is the foundation of maintaining creature multiplicity in water body. The instauration of submerged macrophytes is the key of ecological restoration.The environmental effect created by submerged macrophytes is the important basis of ecosystem stabilization and water environmental quality booster. So it is necessary to study synthetically the water effect made by submerged macrophytes on polluted water body. Based on the previous studies and combined with the fifteenth national important scientific special item "863"-the item of water environmental quality improvement and synthesis demonstration about Suzhou City,the research in this paper was carried out. The main work in the thesis is summarized as follows:(1)The frost resisting submerged macrophytes- Elodea nuttallii was chosen as investigated. Based on indoor static experiments, their water improvement effect in different seasons is revealed.(2)Study the biomass impact on water improvement effect by different kinds of submerged macrophytes.The results interpreted from the experiments provide the reference to project.(3)The water improvement effects from different kinds of submerged macrophytes were studied according to contrastive experiments.(4)Due to the different requirements on habitat condition from different submerged macrophytes, the water improvement effects were studied by making artificial waste water charactered with different ratio of nitrogen and phosphorus in different water quality.Through the above studies,the following conclusions were gained:(1)Elodea nuttallii can survive through a year and the maximal biomass appears in autumn. The seasons representing better water improvement effect were autumn and summer;(2)In a given range of biomass with the increase of biomass,the water improvement effects by Elodea nuttallii ,Potamogetor crispus and Hydrillaverticillata become more obviously.(3)Compare the water improvement effects from Hydrilla verticillata,Vallisneria spiralis,Elodea nuttallii and Ceratophyllum demersum.The conclusion showed that Hydrilla verticillata gives the best choice for improving water quality of polluted water.(4)Water improvement effect of submerged macrophytes varies with the different water quality.The adaptive faculty of Hydrilla verticillata and Ceratophyllum demersum is higher than that of Vallisneria spiralis and Elodea nuttallii.