Research On Influence Factors Of Submerged Macrophytes Restoration In Eutrophic Water

Eutrophication is one of the most important environmental problems in our country,which had led to a series of ecological and environmental problems.Until now,there are many ways to control the eutrophication of water.Among them,the technology of aquatic plants remediation,especially the submerged macrophytes remediation,were considered to be one of the most effective methods,and were widely used in the treatment of lakes,rivers and other water bodies.The research on the influence factors of submerged macrophytes restoration in eutrophic water could help to improve the efficiency of submerged macrophytes restoration,which could also help to exert the ecological function of submerged macrophytes and control the eutrophication of water.Domestic and foreign scholars had done a lot of research on the restoration of submerged macrophytes in eutrophic water,those reserach mainly focused on the effect of light intensity and overlying water on the growth of submerged macrophytes.Few studies on the influence of sediment characteristics on submerged plant growth had been conducted.However,sediment is the base of the submerged macrophytes’ roots,and it is also the important source of nutrient which submerged macrophytes need to absorb.As a result,the sediment characteristics would have an important influence on the growth and the physiological characteristics of submerged macrophytes,which should not be ignored.Based on that,this study established an outdoor 70d experiment to examine the effects of sediment properties on the growth and the physiological characteristics of submerged macrophytes.In the experiment,seven submersed macrophytes,Vallisneria natans,Hydrilla verticillata,Potamogeton maackianus,Potamogeton malaianus,Potamogeton lucens,Potamogeton perfoliatus and Myriophyllum spicatum were cultured on five sediment mixtures consisting of different proportions in lake sediment and local soil from the Lake Erhai.The influence mechanism of sediment properties on submerged macrophytes had also been preliminary discussed in this research.The results show that:(1)V.natans,P.malaianus and P.lucens grown on the sediment mixture of 50%deep-layer lake sediment and 50%local soil,which had the highest shoot heights,and so did for H.verticillata,P.maackianus,P.perfoliatus and M.spicatum grown on the 100%deep-layer lake sediment.On the 100%deep-layer lake sediment,V.natans,H.verticillata,P.maackianus,P.malaianus and P.lucens had the highest relative growth rate(RGR)and biomass production,and so did for P.perfoliatus and M.verticillatum grown on the 100%surface lake sediment,and the sediment mixture of 50%surface lake sediment and 50%deep-layer lake sediment respectively.All the plant species did not grown well and got marginal biomass production on the 100%local soil.(2)The water content of the sediment,The concentration of nutrients in the sediment interstitial water and the C,N and P contents of the sediment would all affect the growth and the physiological characteristics of submerged macrophytes.The influence mechanism of sediment properties on submerged macrophytes would be related with the process of absorbing the nutrient.Although the impact mechanism is similar,the effect of sediment properties on the growth of submerged macrophytes may vary depending on the species of submerged plants.(3)All the 7 submerged macrophytes need to grow on the sediment which have the best range of sediment properties.Within the range,the growth of submerged macrophytes would be significantly promoted,while insufficient or beyond this range,the sediment properties would inhibit the growth of the submerged macrophytes,the accumulation of biomass would be inhibited neither.This would even led to the disappearance of submerged macrophytes.