【作者】 米玮洁；

【导师】 朱端卫；

【作者基本信息】 华中农业大学 ， 植物营养， 2008， 博士

【摘要】 沉水植物恢复是富营养化湖泊生态恢复的重要措施,但目前沉水植物很难在富营养湖泊中存活生长,环境中的营养物质水平对沉水植物生长有着重要影响。本文通过在室内进行的太湖、汤逊湖和月湖沉积物中的沉水植物菹草栽培实验,从沉积物矿质营养角度研究了不同富营养化湖泊沉积物中菹草的恢复过程,比较了不同湖泊沉积物中菹草长势的差异,菹草营养含量及变化趋势的差异;在菹草恢复生长后,研究菹草对水体pH的影响及菹草根斑的形成,通过比较种菹草处理和不种菹草对照中沉积物-上覆水营养含量的差异,研究菹草生长过程中对沉积物-上覆水营养水平产生的影响。通过研究,得到如下主要结果:1)通过研究不同底质和上覆水类型中菹草的生长发现,太湖表层沉积物促进菹草的营养生长,对繁殖体的产生有抑制作用;石英砂底质不利于菹草茎叶生长,利于繁殖体产生。菹草体内Ca、Mg含量主要受上覆水营养水平的影响;Fe、Mn含量主要受沉积物营养水平的影响;Cu、Zn含量受上覆水和底质营养水平的共同影响。2)通过比较菹草在太湖、月湖和汤逊湖沉积物中的长势发现,菹草在太湖、月湖和汤逊湖沉积物中均能生长良好,但菹草长势在3个湖泊沉积物中表现出明显差异,太湖沉积物中菹草长势好于月湖,汤逊湖沉积物中菹草长势最差。不同湖泊沉积物中菹草茎叶生物量、根系生物量和繁殖体生物量都表现出明显的差异,且不同湖泊沉积物中菹草繁殖体的发芽率有差异。3)通过研究菹草在太湖和月湖不同样点沉积物中的生长发现,菹草旺盛的营养生长有利于繁殖体产生,但菹草繁殖体发芽率与菹草长势没有表现出相关性。沉积物营养水平与菹草长势具有一定的相关关系:在菹草生长初期沉积物营养丰富抑制菹草生长,随着菹草生长,沉积物营养的影响作用降低;旺盛生长期后,沉积物锰含量丰富促进菹草生物量增加;沉积物中高磷、铜和锌含量会抑制菹草繁殖体产生。4)菹草体内不同营养元素的含量表现出明显而又不同的季节性变化。不同湖泊沉积物中菹草体内相同营养元素含量的季节变化表现出相似性,沉积物对菹草营养含量有影响,但不会改变其季节性变化趋势。不同营养元素在菹草体内的分布具有差异,一般表现为:Fe、Mn、Zn,根系＞茎叶＞繁殖体;Mg,茎叶＞根系＞繁殖体;繁殖体中P、Ca含量低于茎叶和根系;繁殖体Cu含量则居于茎叶和根系之间。菹草不同部位营养含量受沉积物营养水平的影响,相较于茎叶和根系而言,菹草繁殖体营养含量受沉积物营养水平的影响较小。5)随着菹草生长,上覆水pH明显升高,光照对菹草影响水体pH值有重要作用,使得菹草生长的上覆水pH表现出明显的日变化。除菹草生长对上覆水pH有影响外,沉积物类型对上覆水pH也有直接和间接的影响。6)菹草根斑的形成导致根斑处根系表面元素富集,影响根系对营养元素的吸收,进而影响元素在根系截面的分布。菹草根斑形成对菹草根系表面Fe、Mn、Si、P营养有明显影响,对Al、Ca也有一定的影响,而对于Mg、Cu、Zn没有影响。不同沉积物中菹草根斑对根系表面营养元素的富集及含量的影响表现出差异。7)与不种菹草对照相比,菹草生长对沉积物水浸提营养含量、间隙水和上覆水营养含量均有影响,在不同时期对不同营养元素含量的影响表现出了复杂性,在汤逊湖和月湖沉积物不同底质中也表现出了明显的差异。菹草生长后一般在返青期和旺盛生长期对营养含量的季节变化有比较明显的作用。菹草生长对上覆水营养含量的变化趋势影响较小,而对沉积物水浸提营养含量、间隙水营养含量的变化趋势具有明显影响。更多还原

【Abstract】 The recovery and growth of aquatic submersed macrophytes is an important and effective measure for phytoremediation of eutrophic lake ecosystem.But so far it was difficult for aquatic submersed macrophytes to grow successfully in eutrophic lake.In this process,nutritional levels in the environment had great influence on the submersed macrophytes growth.Through the transplanted experiments of submersed macrophyte Potamogeton crispus L.in Taihu Lake,Tangxunhu Lake and Yuehu Lake sediment in the laboratory,from the view of mineral nutrients,we studied the growth of P. crispus in different lake sediment,by comparing the variance of P.crispus growth,nutrients content and seasonal change in different lake sediment.And after P.crispus grew successfully,we kept on the study of the influence of P.crispus growth on water pH,the formation of root plaques around root,the effects of P.crispus growth on nutritional levels in sediment and overlying water by comparing the variance of nutrients content in sediment and overlying water between treatments of P.crispus growth with controls of no P.crispus growth.Through the study,we got the primary results as followed:1) By the study of P.crispus growth in different types of substrate and overlying water,we found that as surface sediment of Taihu Lake was substrate,P.crispus shoots growth was advanced while propagules generation was inhibited.As quartz sand was substrate,P.crispus shoots growth was inhibited while propagules generation was advanced.The concentration of Ca and Mg in P.crispus was mainly influenced by Ca and Mg concentration in overlying water.The concentration of Fe and Mn in P.crispus was mainly influenced by Fe and Mn levels in sediment.The concentration of Cu and Zn in P.crispus was influenced by overlying water and sediment at the same time.2) By comparing P.crispus growth in Taihu Lake,Yuehu Lake and Tangxunhu Lake sediment, we found that P.crispus could grew well in all sediments,but there was difference for P.crispus growth in different sediment.P.crispus grew better in Taihu Lake sediment when compared with that in Yuehu lake sediment;P.crispus grew worst in Tangxunhu Lake sediment.There were significant differences for shoots biomass,roots biomass,propagules biomass and germination rates in different sediments.3) By the study of P.crispus growth in sediment of different sites in Taihu Lake and Yuehu Lake, it was found that flourish shoots growth would be helpful for the generation of propagules of P. crispus,although there was no corresponding relationship between germination rates of propagules with P.crispus growth.The significant relationship existed between sediment nutritional levels and P. crispus growth.In the initial stage of P.crispus growth,the enrichment of nutrients in sediment inhibited shoots growth.With the time gone,influence of sediment nutritional levels became weak gradually.After the period of flourish growth,there was significant positive relationship between Mn content in sediment with biomass of P.crispus.The enrichment of P,Cu and Zn in sediment would inhibit the propagules generation.4) The different nutrients in P.crispus represented obvious and different seasonal changes.The same nutrient had similar seasonal changes in tissue of P.crispus growing in different sediment.The nutritional levels in sediment had influence on the nutrients concentration in P.crispus,while had no influence on the trend of seasonal changes of nutrients in P.crispus.There were differences for the distribution of different nutrient elements in plant tissue.In general,Fe,Mn and Zn conc.were highest in roots,then in shoots,lowest in propagules.Mg conc.was highest in shoots,then in roots,lowest in propagules.Ca and P conc.were lowest in propagules compared with shoots and roots.Cu conc.in propagules was in-between of shoots and roots.Nutrients conc.in different parts of P.crispus was influenced by the nutritional levels in sediment.Compared with shoots and roots,the influence of sediment was less in nutrients concentration in propagules.5) With P.crispus growth,pH of overlying water was significantly elevated.The illumination had great influence on the changes of pH in overlying water,which caused overlying water pH represented diurnal changes.Beside of P.crispus growth,substrate had some influence on the pH changes of overlying water by direct and indirect effects.6) The formation of root plaque around P.crispus root caused elements concentrated in the root surface,further influenced the elements uptook by roots and elements distribution in root section.Root plaque formation around the roots of P.crispus had influence on Fe,Mn,Si and P conc.and distribution in root surface and section,had some effects on Al and Ca,while had no effects on Mg, Cu and Zn in roots.For the different characteristics of root plaque formation around roots in Tangxunhu Lake sediment and Yuehu Lake sediment,the influence of root plaque on nutrient elements uptook by roots was different between P.crispus grew in Tangxunhu Lake sediment with Yuehu Lake sediment.7) Compared with the control,P.crispus growth had influence on the water-extracted nutrients conc.in sediment and nutrients conc.in pore water,overlying water.The effect of P.crispus growth on water-extracted nutrients conc.in sediment,nutrients conc.in pore water and overlying water was complicated for different time,different nutrients and different sediment.Generally,after the period of returning-green and flourish growth,the influence of P.crispus growth became more obvious.P. crispus growth had less influence on the nutrient conc.changes in overlying water,by comparing with the influence on changes in water-extracted nutrient conc.and nutrient conc.in pore water.更多还原