Accumulation And Biological Cycle Of Mentals In Spartina Alterniflora Vegetation

Wetland is a natural sythesis with particular location that is between ocean and land,it is also a very high-productuve ecosystem in nature. Wetland plays a non-substituted role in source self-restraint,withstanding flood,controlling pollution.The biogeochemistry process in tidalflat is very complicated in that frequent exchange of chemical materials with adjacent ecosystem.Macrophytes in wetland play an importand part in biogeochemistry,Which always absorb all kinds of elements from the sediment,water,and air,including plant nutrient and heavy mentals. Element contents in the sediment also affect element cycle in ecosystem. As one of the important issues of the global elements cycle,nutrient and heavy mentals cycle in wetland is an issue for ecologist all the time.The research on the characteristics of these elements in wetland can contribute to wetland system research and supply the basis for protecting wetland as well as rebuilding degenerative wetland.However,as a high-productive plant in tidalflat,element cycle in Sp.alterniflora community is still limited up to the present.The dissertation was supported by Natural Science Foundation of Zhejiang Province:"Study on tidalflat diking affect wetland system and diking pattern in Zhejiang Province".Sevaral typical Sp.alterniflora communities of tidalflat in Wenzhou were chosen(Sp.alterniflora is sole dominant plant).Sediment and the plant(aboveground part and root) were collected respectively in August,2005,November,2005,April, 2006 and Jannury,2007.According to field work and indoor experiments, the research focus on seasonal biomass dynamics of aboveground part and root,as well as concentration and content seasonal dynamics of K,Ca,Na,Mg,Pb,Cr,Cu,Zn in different part.Eight elememts concentration seasonal dynamics in soil and the circle characteristic of elements in ecosystem are analyzed.According to different circle characteristic of eight elememts,we search after effective approach to fathering and making use of wetland.Major conclusions from the research are as follows:1,During growth seasons of Sp.alterniflora,both aboveground part and root have more high biomass.In four seasons,aboveground biomass is higher than root biomass.Both aboveground and gross biomass seasonal dynamics are summer＞autumm＞spring＞winter.The reason is that in winter most of aboveground part is dead standing resulting in small biomass.In spring,the root always exists in the manner of stem,so for root dynaics,the result is summer＞winter＞autumm＞spring.The biomass disparity between winter and autumm is very small,only is 0.176g/m~2.As concerned as the percentage of different part biomass,in winter,root biomass has the highest ratio to gross biomass,the second is summer,the smallest is spring.2,In aboveground part and root of the plant as well as in soil,different elememts have various seasonal content dynamics.In three plots,the same element content have similar trends.The main types are as follows: (1)handstand "V" type:including K Na Mg content in soil and Cu\Zn in plant;(2)anomalistic "J" type:including Ca and Pb content in plant; (3)handstand "S" type:Mg content in plant\Cu and Zn contents in soil; the remained all show "V" type trend.3,We mainly use absorption coefficient,circulation coefficient and utilization coefficient to token circulation characteristic in elememt circle.The results show:among constant elements,according to numbers,both absorption coefficient and utilization coefficient are Na＞K＞Ca＞Mg;but circulation coefficient is Ca＞Na＞K＞Mg.For heavy mentals,absorption coefficient is Zn(0.01)＞Cu(0.009)＞Pb(0.006)＞Cr(0.003);utilization coefficient is Cr(0.929)＞Cu(0.919)＞Zn(0.88)＞Pb(0.442);circulation coefficient is Zn(0.455)＞Pb (0.339)＞Cu(0.173)＞Cr(0.094).4,In plant body,elememt contents distribution is aboveground part＞root.In aboveground part,mental contents are Na＞Mg＞Ca＞K＞Zn＞Cr＞Pb＞Cu;but in root,mental contents are Na＞K＞Mg＞Ca＞Zn＞Cr＞Pb＞Cu.Different heavy mentals have various accumulation coefficients in Sp.alterniflora.For example,in aboveground part,accummulation coefficient is Zn(0.623)＞Pb(0.515)＞Cu(0.457)＞Cr(0.393)and whichis Zn(1.684)＞Cu(0.743)＞Cr(0.655)＞Pb(0.662)in root.5,In Sp.alterniflora,different heavy mentals have various transfer coefficients,the resultis Pb(0.778)＞Cu(0.615)＞Cr(0.6)＞Zn (0.37).