Comparison Of Sand Culture And Floating-Bed Culture Oenanthe Javanica For Wetland Purification Ability In Winter

The floating bed is widely adopted in the artificial wetland construction technology.Most internal and external researches on the floating bed wetlands are confined within the qualitative analyses or description seldom are quantitative ones.To improve the purification ability of wetland in cold winter and study the impact of culture methods of wetland plants,traditional surface flow constructed wetland and floating bed wetlands are constructed,in Hongze field experiment base.A pilot-scale experiment was conducted to compare the performance of O.javanica(Oenanthe javanica(B1.)DC.)using two culture methods,i.e.sand culture(SC)and floating-bed culture(FBC),in the purification of polluted water during wintering period.the main popuse is probing problems purification ability of artificial wetland,wintering ability of O.javanica,diversity of microbial communities,and absolute abundance of functional genes of nitrogen metabolism The results showed that:(1)Compared with CK,the results showed that the plantation of O.javanica could significantly improve TP and TN removal efficient in cold winter.Compared with FBC,SC had slightly higher removal ability for both TP and TN.There existed significant different removal efficiencies of Total Phosphorous(TP)and Total Nitrogen(TN)between treatments.In the four studied batches,control check(CK),SC and FBC showed an average of(20.17±19.23)%,(59.60±7.54)%and(45.44±29.22)%TP removal efficiency,and an average of(29.83±19.65)%,(64.89±23.01)%and(60.50±25.86)%TN removal efficiency,respectively.(2)O.javanica cultured of both the two methods FBC and SC can survive the winter.Compared with SC,FBC is more advantageous to the increase of total plant biomass,especially the biomass of root system.And root system biomass of FBC have been significantly greater than SC all the time.Meanwhile,the FBC' slitter mass was also significantly higher than SC during batches ?,? and ?.(3)Compared with FBC,traditional culture method SC keep the root activities high and root oxygen release of O.javanica active,within the over-wintering stage.Thus,the TN removal process of SC is smoother than FBC.All the root activities data of SC are higher than FBC except that is significantly lower in SC(FBC(p=1.58E-4),in batches ?.Root oxygen release has a similar variation tendency to the root activities.(4)Both two kinds of wetlands are favorable for bacteria belonging to class Proteobacteria growth,relative abundance of bacteria in S.ro.SC is higher than that in S.st.SC,and is higher than that in S.r.FBC.At the same time Aeromonas spp.in S.st.SC is higher than that in S.ro.SC.and S.r.FBC.16S rRNA results shows that dominant class of samples separated from O.javanica tissue are y-proteobacteria with a testing result of 60.8%(S.st.SC)>41.9%(S.r.FBC)>24.4%(S.ro.SC)and the dominant family Aeromonas spp.with a result of 24.3%(S.st.SC)>2.8%(S.ro.SC)>2.2%(S.r.FBC).(5)The Real-time PCR results shows that in the two types of wetlands,absolute abundance of amoA gene related to ammoxidation showed great discrepancy.In the FBC,amoA gene concentrated in the root.However,in SC it appears in the sand near root system.Test results of amoA gene in samples of O.javanica tissue are S.r.FBC:(9.77E+12±7.78E+12)copies/g;S.ro.SC:(2.20E+12±3.71E+11)copies/g;S.st.SC:(1.41E+12±8.49E+11)copies/g;and sand results are S.s.FBC:(6.20E±11±1.07E+12)copies/g;S.sa.SC:(1.38E+12±2.32E+12)copies/g;S.sr.SC:(2.03E+13±1.46E+13)copies/g.Therefore,considering the engineering costs,the traditional sand(or sediment)culture method is recommended at the shallow water areas where O.javanica can survive using either SC or FBC.For the deep water areas where O.javanica can't survive using SC,we can use FBC which can also perform relative high purification ability and make O.javanica survive in the temperate winter.