Research On ROL Of Wetland Plants And Its Impact On Removal Of N,P Nutrient In Dianchi

With the increase of population, the development of industy and agriculture and the aggravation of irrational human exploiting activities, numbers of lakes and coastal zones degenerated severely and its ecological functions weakened because of human disturbance, becoming a direct threat to the environment on which humans and aquatic organisms rely. The degradation of lakes and coastal zones will easily lead to the destruction of vegetation, decline of biodiversity, deterioration of water quality, decrease of aesthetic values and floods frequently, further affect people's health and property, so the importance of wetlands to lakes and coastal zonesthe could be seen evident. Wetland plants played an important role to wetland treatment system, such as removing pollutants, radial oxygen loss, strengthening and sustaining the hydraulic transmission, providing micro-habitats, improving ecological aesthetic and economic value, so the selection of wetland plants in the construction of wetland treatment system was particularly important. The selection of wetland plants tend to focus on biomass, purification ability and landscape effects, but because their characteristic of radial oxygen loss could form the oxidation state micro-environment at the roots of the plant, provide the micro-living environment for the aerobic microorganisms, promote the absorption and degradation of the pollutants, also can oxidize the toxic substances which have reducing property due to the oxygen poor during long period, and promote the absorption of the nutrients of the plant, result in the radial oxygen loss into the focal point of wetland plants in recent years.The characteristics of radial oxygen loss of eight kinds of wetland plant along with Dianchi Lake were studied in this paper, and the effect of the wetland plants to the removal of TN,TP from the Dianchi Lake were researched through the static hydroponic and puring experiments, and further draw on the correlation of radial oxygen loss and the removal of TN,TP, to make the wetlands to maximize pollution control function.Contents and results of this research are as follows:(1) Eight kinds of wetland plants, The C.indica, Zantedeschia aethiopica Spreng, Zizania Caduciflora, Acorus calamus Linn, Typhaangustifolia, Arundo donax, Sagittaria pygmaee Miq and Oenanthe stolonifera D.C were acclimated hypoxia, the radial oxygen loss of wetland plants were studied by using the method of citric acid titanium, and determined rates of radial oxygen loss of wetland plants described under different environmental conditions, the influence of the light intensity and environmental temperature on radial oxygen loss of wetland plant were studied. The results showed that: the rate of the radial oxygen loss of wetland plants increased with the light intensity, decreased with the temperature rised. Under the condition of light intensity at 30μmol ? m-2 ? s-1, the ambient temperature at 25℃, humidity at 50%, In the eight kinds of wetland plants, the largest radial oxygen loss rate from the roots was Acorus calamus Linn, which was 6.736μmolO2 ? h-1 ? groot-1, the smallest was Arundo donax at 1.208μmolO2 ? h-1 ? groot-1, the order arranged by descending the rate of the radial oxygen loss was: Acorus calamus Linn>Sagittaria pygmaee Miq> Zantedeschia aethiopica Spreng>Zizania Caduciflora>Typhaangustifolia> Oenanthe stolonifera D.C.> C.indica > Arundo donax.(2) The results of purifing N,P nutrients of Dianchi Lake by wetland plants were discussed and compared with control system without plants, the results showed that: the removal effects of TN, TP from each plant system were higher than the control system except Sagittaria pygmaee Miq, the TN removal rate of C.indica,Acorus calamus Linn,Arundo donax,Typhaangustifolia,Zantedeschia aethiopica Spreng were all above 70%, the TN removal efficiency by Zizania Caduciflora and Oenanthe stolonifera D.C. were poor, only 53.04% and 36.15% respectively, the removal efficiency of TN by each plant system were arranged as: C.indica> Acorus calamus Linn>Arundo donax>Typhaangustifolia>Zantedeschia aethiopica Spreng>Zizania Caduciflora>Oenanthe stolonifera D.C.; Oenanthe stolonifera D.C. was ineffective on the removal of TN, but had strong absorption for TP, the removal rate reached 74.8%, the removal rate of TP by C.indica, Zantedeschia aethiopica Spreng were all reached 60%, the removal rate of TP by Zizania Caduciflora,Acorus calamus Linn and Typhaangustifolia were all above 40%, the worst effects on TP was Arundo donax, only 36.24%. The effect of removal TP of every plant systems was, Oenanthe stolonifera D.C.> Zantedeschia aethiopica Spreng>C.indica>Zizania Caduciflora>Acorus calamus Linn> Typhaangustifolia > Arundo donax.(3)The data of the rate of the radial oxygen loss of wetland plant and the N,P nutrient removal in Dianchi Lake were analysised by Origin software, the results showed that the rate of the radial oxygen loss of wetland plant were existed a positive correlation with the removal of TN,TP nutrients from the plants in Dianchi Lake, that is to say, with the increase of ROL, the removal of TN,TP increase.