| This simulation experiments in order to study the effect of artificial additive different concentrations of hexavalent chromium(0,5,20,40,60mg/L)on wastewater of and vertical flow Coix aquatica Roxb constructed wetlands(YMW) and no Coix aquatica Roxb constructed wetlands(NPW), nutrientsource by1/2hoagland’s nutrient solution. Study the effects of Coix aquatica Roxb growth and development trends、respond of physiology and uptake microelement such as Fe、Mn、Cr and so on, and meanwhile study the effects of two types constructed wetlands purification hexavalent chromium effects、microbiologic community population and so on. The results showed:1The effect of purification of Ammoniacal Nitrogen(NH3-N), total Nitrogen (TN),Hexavalent chromium(Cr6+)in YMW better than NPW, the lower Cr6+concent-ration(5mg/L) would enhance uptake NH3-N,higher Cr6+(40,60mg/L)treating show inhibition effects following treating times extend in YMW and NPW. As treating time extend showed rise then reduce effects purification of TN in YMW, Cr6+treating showed purification TN significance inhibition effects in NPW.There is no different effect purification TP in two types of constructed wetlands,other treating stages removal rate hold90%except NPW purification TP showed reduce effects.The lower and middle Cr6+concentrations(5,20mg/L) treating showed better effects purification Cr6+in YMW, the removal rate reach99%,but higher Cr6+concentrations(40mg/L) treating showed inhibition effects.2The effects of SOD activity of Coix aquatica Roxb leaf rise with constant extend growth stages,5mg/LCr6+concentration treating showed enhelped SOD activity in earlier growth stage of Coix aquatica Roxb,40mg/LCr6+concentration treating showed promoting enhance SOD activity in varying degrees as treating time extend.The different Cr6+concentration treating showed enhance POD activity,MDA content of Coix aquatica Roxb leaf, POD activity rise with Cr6+concentration treating at earlier and middle growth stage of Coix aquatica Roxb,and MDA content rise with Cr6+concentration treating at whole stages.The lower and middle Cr6+concent-ration(5,20mg/L) treating showed enhanced SP content of Coix aquatica Roxb leaf,and SP content rise with treating times extend,but higher Cr6+concentration (40mg/L) treating showed inhibition effects at later stages.3Lower Cr6+concentration(5mg/L) treating showed enhance Pn,Gs,Tr of Coix aquatica Roxb leaf,other Cr6+concentration treating showed inhibition effects. Ci of Coix aquatica Roxb leaf appear reduce with Cr6+treating times, middle and higher Cr6+concentration(20,40,60mg/L) treating showed significance promoting enhance Ci,and rise with Cr6+concentration treating rise.4Microorganism communities population showed YMW more than NPW, the effect of fungi,bacteria,actinomycetes communities population showed similar as treating effect.The fungi population variation trend appear constant increase with treating times extend, the bacteria population in YMW showed constant increase with treating times,but the actinomycetes population appear increase then reduce effects with treating times extend.The different Cr6+concentration treating showed enhanced bacteria,actinomycetes communities population,and also enhanced fungi population of NPW; the lower and middle Cr6+concentration(5,20mg/L) treating showed enhanced fungi population of YMW, higher Cr6+concentration(40,60mg/L) treating showed inhibition effects, bacteria population of NPW and actinomycetes population of YMW showed all increase with Cr6+concentration treating increase.5The urease activit and catalase activit of constructed wetlands matrix showed NPW more than YMW, urease activit in the two types of constructed wetlands matrix showed constant decreased along with treating times extend. The lower Cr6+concentration(5mg/L) treating appear enhance effects for urease activit of YMW and catalase activit of NPW, meanwhile also enhance effects for urease activit of NPW in May and July,middle and higher Cr6+concentration(40,60mg/L) treating showed inhibition effects of urease activit for two types of constructed wetlands, catalase activit appeared similar as effects,but different Cr6+concentrations showed enhanced urease activit of NPW in Juiy. The lower and middle Cr6+concentrations(5,20mg/L) treating showed inhibition effects for catalase activit of YMW,and inhibition effects appeared increase with Cr6+concentrations treating increase,but higher Cr6+concent-rations (40mg/L) treating showed significance promoting effects.6The contents of Mn,Zn,Cu in Coix aquatica Roxb plant were as follows:root> leaf> stem; The contents of Fe and Cr were as follows:root>stem> leave. At the early growth stage Cr6+inhibited the absorption of Fe,Zn,Cu in roots, low concentrations of Cr6+helped to the absorption of Mn and Cr, but higher concentrations inhibited in root; afterward time Fe, Mn, Cu, Cr contents decreased along with concentrations increase, but middle and higher concentrations of chromium promoted the Zn absorption.The absorptions of Fe, Zn, Cu in stems have the varying degree inhibitory action under the Cr6+treatment processing, the Mn absorption promoted under the treatment of5mg/L Cr6+concentration and decreased gradually with the increase of Cr6+concentrations; at the early and middle growth stage,the content of Cr6+in stems gradually increased along with the enhancement of Cr6+concentration, and it was significantly promoted under the treatment of20mg/LCr6+in September. Cr6+helped to the absorption of Zn and Cr in leaves at the early and middle growth times,the contents of Fe,Mn,Cu in leaves decreased with the increase of Cr6+concentrations at some times.7The lower Cr6+concentration (5mg/L)treating showed would be enhance Coix aquatica Roxb height elongation,but higher Cr6+concentrations (20mg/L and above)treating showed inhibition effects, the with inhibition effects showed significance enhance with the increase of Cr6+concentrations;There is no significantly differents that diameter of Coix aquatica Roxb stem base under Cr6+stress. Tillers showed Cr6+concentrations rise then reduce effects from May to July, the lower Cr6+concentration (5mg/L)treating showed would be enhance total length of root, the higher Cr6+concentrations(40mg/L) showed inhibition effects;the surfarea, root volume, dry matter weight showed effects similar as total length of root.8Correlation coefficients between fungi population in YMW and purification of TN、TP have negative contrast, Correlation coefficients between bacteria population in YMW and purification of NH3-N have negative contrast; Correlation coefficients between urease activit in NPW and purification of TN have positive contrast, Correlation coefficients between purification of NH3-N and purification of TN> Cr6+all havepositive contrast, Correlation coefficients between purification of TN in YMW and purification of Cr6+have positive contrast. Correlation coefficients between Fe,Mn,Cu and Zn of Coix aquatica Roxb roots all have positive contrast, There is not antagonism effects between Fe,Mn,Cu and Zn of Coix aquatica Roxb stems,but Correlation Cr and four microelement showed different effects, Correlation coefficients between Fe and Cu of Coix aquatica Roxb leavies have positive contrast, Correlation coefficients between Zn and Cu of Coix aquatica Roxb leavies have positive contrast, Correlation coefficients between Cr and Cu of Coix aquatica Roxb leavies have positive contrast, but Correlation coefficients between Zn and Mn of Coix aquatica Roxb leavies have negative contrast. Correlation, coefficients between SOD、POD and Fe content of Coix aquatica Roxb leavies have positive contrast, Correlation coefficients between POD and Mn,Cr content of Coix aquatica Roxb leavies have positive contrast, Correlation coefficients between SP content and Zn have positive contrast. |
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