The Correlation Analysis Between Sediment Nutrition And Emergent Hydrophytes Growth Status Of Landscape Waterbody In Shanghai

Sediment as a carrier and nutrition resource of emergent hydrophytes,which is closely related to emergent hydrophytes growth.Thus,it is of great significance to study the relationship between sediment nutrition and the growth status of emergent hydrophytes.In this paper,we focused on typical landscape waterbody in Shanghai,analyzed the sediment nutrition relation with 5 kind of emergent hydrophytes and discussed the effect of biochar on the improvement of the sediment.The main conclusions are as follows:63 species of aquatic plants were observed from 9 typical landscape waterbodies,which belong to 42 genera and 33 families.The main plant is emergent hydrophyte and accounting for 71.4%of total species.The water quality is generally good and it is better in summer than winter,however,it fluctuate obviously in summer.The sediment of landscape waterbody shows weakly alkaline,low phosphorus content,medium to low fertility.The variation coefficient of sediment nutrition performances high in summer and low in winter.K-W test for multiple independent samples of the 5 kind emergent hydrophytes growing conditions shows that there's a significant difference between growth and physiological indexes(p<0.05).Factor analysis and comprehensive method were used to evaluate the growth situation of Iris pseudacorus,Thalia dealbata,Lythrum salicaria,Pontederia cordata and Arundo donax var.versicolor.The growth situation of emergent hydrophytes can be preliminarily classified as individual features,comprehensive features and community features as the 3 main factors.The cumulative variance explained are 92.842%?81.799%?93.045%?87.100%and 84.024%,respectively.Correlation analysis indicates that the growth situation of Iris pseudacorus,Thalia dealbata and Arundo donax var.versicolor are closely related with the total phosphorus content in sediment.Among those,Lythrum salicaria and Pontederia cordata are the most relevant emergent hydrophytes.The releasement of sediment nutrient elements was promoted by adding different proportions of biochar to different nutrition level of sediment.The biochar has great influence on the physical and chemical properties of overlying water at the beginning.It can not only purify nitrogen and phosphorus in the overlying water when it is stable,but also adjust the sediment pH value effectively,inhibit the releasement of alkali-hydro,increase the sediment organic matter,available phosphorus and total nitrogen content.However,there is no significant influence on sediment EC and the effects on total phosphorus needs further research.The growth of Lythrum salicaria is benefit of the addition of biochar added into the low trophic level sediment,while inhibited in high nutrient sediment.