The Effects Of Boric Acid On Uranium And Its Associated Heavy Metals Accumulation In Medicago Sativa L.

This paper aimed at improved the enrichment efficiency of U and associated heavy metals in the high biomass Uranium enrichment test plants Medicago sativa L.,Rumex acetosa L.and Cichorium intybus L.by appling boric acid in the Uranium tailings reservoir pollution area for field experiments to analyze the effects of boric acid on the growth and physiological and biochemical indexes of alfalfa under Uranium and associated heavy metals stress and the enrichment characteristics of the three species of Medicago sativa L.,Rumex acetosa L.and Cichorium intybus L.The main conclusions are as follows:1.The effects of boric acid and mowing on the growth and physi-ological and biochemical indexes of alfalfa under U and associated heavy metals were:(a)The plant height,dry weight,leaf area and carbon fixation of Medicago sativa L.planting in applied boric acid and Mowing area were respectively increased by 4.45%/21.94%,5.72%/23.78%,6.93%/9.01%5.71%/24.04%compared with the control.(b)The photosynthetic parameters(Ci,E,Gs,A)of Medicago sativa L.planting in applied boric acid and mowing area were respec-tively increased by 4.45%/21.94%,5.72%/23.78%,6.93%/9.01%,5.71%/24.04%;the fluorescence parameters(Fv/Fm,Fo/Fm,ETo/ABS,ABC/RC.PIABS)were respectively increased by 0.0281/0.1102,-0.0281/-0.1102,0.0151/0.0526,0.0083/-1.8848,0.0812/0.3903;the chlorophyll a,chlorophyll b,carotenoid were respectively increased by 10.79%/6.85%12.51%/3.04%1.28%0.3%;and the SOD,POD,CAT and free proline were respectively increased by 1.98%/9.6%,3.43%/7.99%9.18%/12.78%1.59%/5.09%compared with the control.(c)The enrichment of U,Mn,Co,Ni,Zn and Cd in Medicago sativa L.planting in applied 1.5 Kg/acre of boric acid and Mowing area were respectively increased by 18.8%/11.10%11.01%/8.18%-3.37%/3.17%,-0.20%/2.45%22.9%/14.36%11.3%/5.43%compared with the control.2.The enrichment Characteristics of U and Associated Heavy Metals in Medicago sativa L.,Rumex acetosa L.and Cichorium intybus L.The enrichment of U,Mn,Co,Ni,Zn and Cd in Medicago sativa L.Rumex acetosa L.and Cichorium intybus L.respectively reach the maximum value 9.853/309.014/16.748,101.986/9676.155/393.801,9.607/784.810/35.354,12.096/439.394/31.975,84.817/1809.498/113.004,3.451/56.861/3.408 mg/Kg;and the transfer coefficients respectively were 0.398/0.563/0.188,1.574/1.906/0.366,0.678/0.499/0.256,2.017/0.773/0.223,4.035/1.418/0.552,1.934/0.797/0.351,when the boric acid concentration respectively is 1.0/1.5/0,2.0/1.0/2.0,0/1.0/1.0,2.5/1.0/1.0,2.0/1.5/1.0,2.5/1.5/2.0 Kg/acre.3.The different occurrence of U in rhizosphere soil around Medicago sativa L.,Rumex acetosa L.and Cichorium intybus L..The interchangeable state,carbonate bound state,organic bound state,amorphous iron manganese oxide/hydroxide bound state,crys-talline iron manganese oxide/hydroxide bound state and residual state of U were respectively increased by 10.87%/9.67%/7.06%,11.70%/11.26/7.73%,7.14%/7.73%/5.78%,-0.24%/-8.13%/-6.09%,-6.82%/-4.38%/-5.71%,-6.70%/-6.27%/-5.51%compared with the control in rhizosphere soil around Medicago sativa L.,Rumex acetosa L.and Cichorium intybus L..