Characteristics Analysis And Evaluation On Hyperaccumulator Of Uranium And Its Associated Heavy Metals

This paper aimed at biological treatment technology of radioactive contamination. Experimental material were Bidens pilosa L., Amaranthus retroflexus L. and Abelmoschus esculentus L., which were high biomass uranium enrichment plants, Brassica juncea L. as model plant. Controlled pot experiments were conducted to find that Abelmoschus esculentus L. has the strongest enrichment ability of uranium and associated heavy metal. Then the analysis of the growth index and physiological and biochemical index of Abelmoschus esculentus L. under uranium and associated heavy metal stress to representation resistance characteristics. And the enrichment characteristics of every elements under the pollution of uranium and associated heavy metal under the complex stress. It provided a reference for the phytoremediation of uranium and associated heavy metal tailings of hyperaccumulators.Main conclusions obtained are as follows:(1) Under the single pollution, the metal concentrations of plant increased with the soil heavy metal concentrations. Under 500 mg/kg uranium stress, the shoot uranium concentration of Brassica juncea L. reached 127.09 mg/kg. The TF of Brassica juncea L. and Amaranthus retroflexus L. was greater than 1 with uranium concentration of 25 mg/kg and 50 mg/kg. The shoot manganese concentration of Abelmoschus esculentus L. was 817.50 mg/kg under 1600 mg/kg manganese stress, and the TF exceed 1 under the various manganese processing. Under 50 mg/kg mercury treatment, the shoot mercury concentration of Brassica juncea L. and Abelmoschus esculentus L. were 24.45 mg/kg and 18.08 mg/kg, and TF were greater than 1, respectively. The shoot lead concentrations of Abelmoschus esculentus L. and Bidens pilosa L. were reached 22.2 mg/kg and 18.00 mg/kg respectively with the soil lead concentrations of 150 mg/kg, but the BCF and TF of four plants under each treatment were less than 1. The shoot arsenic concentration of Abelmoschus esculentus L. reach up to 148.42 mg/kg under high concentration arsenic treatment, and its BCF was 1.41, TF up to 9.02. Brassica juncea L. is suitable for phytoremediation of high concentration of uranium pollution, Abelmoschus esculentus L. is suitable for medium concentration by contrast. By comparison of four kinds of plants, Abelmoschus esculentus L. is more suitable for phytoremediation of manganese, mercury, lead and arsenic pollution.(2) Uranium stress promoted biomass and photosynthetic pigment content of Abelmoschus esculentus L.. Under the high concentration(810 mg/kg) of arsenic stress, the dry weight of shoot reduced to 36.45% of control, and the root dry weight decreased to 32.73% of control, the plant height reduced to 46.92% of the control, it severely inhibited plant growth. Antioxidant enzyme activity with concentrations of heavy metals in soil showed after rising first down. SOD activity reduced 35.21 percent under 500 mg/kg of uranium stress. Under 150 mg/kg of lead stress SOD and CAT activity decreased 11.48% and 12.30% respectively. When the arsenic concentration higher than 270 mg/kg, SOD, POD and CAT activity was significantly lower than the control. The proline content of Abelmoschus esculentus L. increased significantly under the Uranium stress, low concentration of manganese stress, mercury stress, 60 mg/kg and 150 mg/kg of lead stress. The MDA content of Abelmoschus esculentus L.increased 17.08% under 100 mg/kg uranium stress, and increased 23.99% under 800 mg/kg of manganese stress, and increased 13.28% under 90 mg/kg arsenic stress. With the stress protein content of uranium and manganese deepening reduce stress. The protein content of Abelmoschus esculentus L. reduced with the deepening uranium and manganese stress. The plant leaves fluorescence value tended to decrease with soil uranium concentration deepening. Vj and PIabs reduced to 71.11% and 41.01% of the control respectively under 810mg/kg arsenic stress.(3) Under the uranium and associated heavy metals combined pollution, the main metals can promote their own absorbing by Abelmoschus esculentus L., and they are represented by very significant positive correlation; uranium enrichment was negatively correlated with manganese stress(r =-0.9165 **) and arsenic stress(r =-0.622 **); manganese enrichment was positively correlated with mercury(r = 0.4332) and lead(r = 0.4802) threat, and it was negatived correlated with arsenic threat; mercury enrichment was positively correlated with uranium stress(r = 0.6117 **), and it was negatively with manganese stress(r =-0.6966 **) and lead stress(r =-0.6127 **); lead enrichment was positively with manganese stress(r =-0.8559 **) and arsenic threat(r =-0.5407 *); arsenic enrichment was negatively with Mn stress(r =-0.7024 **).