Studies On The Speciation Diversification And Transformation And Transport Of Heavy Metals In Rhizosphere Microzone

Rhizosphere soil and deposits near the shore is influenced by the plant roots and its active micro-zone, the areas is provided with special physical, biological characters. The distribution, accumulation and biological effectiveness of heavy metals in the rhizosphere environment are affected by the hydrological conditions of wetland, the iron plaque in the root of the wetland plants and root exudates.The objects of this paper were about the wetland plants (ash carex) and wetland soils in Nanji Hill in Poyang lake.Using the method of investigation, sampling, rhizospere box experiment, aquiculture experiment and mathematical statistics, this paper studied on the diversification of heavy metals speciation. transport discipline of heavy metals on the conditions of water level and the heavy metal stress (including single Pb stress, single Cu stree and compound Pb/Cu stree). The paper also discussed the iron plaque absorption characters of heavy metal and the correlation between iron plaque and the speciation of heavy metals in rhizospere.The results were:(1) In the rhizosphere box experiment.added single Cu or Pb,the Cu or Pb content in the plant was increased; added Cu and Pb together,the contents of Pb or Cu were more than the contents under the condition on added single Cu or Pb,it showed the synergistic effect. Compared with the control blank group, added single Cu or Pb/Cu together, the Cu element was transported to the ground part of the plants; added single Cu, the Pb element was transported to the ground part of the plants.It was good for the enrichment of heavy metal in the plants. Added single Cu or Pb and added Cu/Pb together, the element of Mn and Fe were transported to the ground part of the plants. It was bad for the enrichment of heavy metal in the plants. The total content of Cu in soil correlated with the content of Cu in the underground part of the plant.The Fe content in the iron plaque correlated with the Fe content in the underground part of the plants.(2)In aquiculture experiment, added single Cu or Pb. the Cu or Pb content in the plant was increased; added Cu and Pb together, the contents of Pb or Cu were less than the contents under the condition on added single Cu or Pb, it showed the antagonistic effect. Compared with the control blank group, added single Cu or Pb and Pb/Cu together, the Cu and Mn elements were restrained to transport to the ground part of the plants, but the Fe element was promoted to transport to the ground part of the plants. Added Pb or Pb/Cu together, the Pb element was promoted to transport to the ground part of the plants. The Pb content in solution correlated the Pb content in iron plaque. The Fe content in the ground part correlated with the Fe content in the underground part in the plants. There was no correlation about Mn.The Cu content in iron plaque correlated with the Cu content in the solution and Fe content in iron plaque.(3)Added Pb, in the rhizosphere (0～4.5mm) environment, it showed that Cu reducible fraction>Cu oxidative fraction>Cu acid soluble fraction and Fe acid soluble fraction> Fe oxidative fraction>Fe reducible fraction.Added Cu, the content of Cu acid soluble fraction was the most near the middle of the root box for1.5～3mm, but the content of Fe reducible fraction is the most for3～4.5mm. The content of Fe oxidative fraction was probably the same. And it also showed that Fe acid soluble fraction>Fe oxidative fraction>Fe reducible fraction.Added Cu and Pb together, it showed that Cu acid soluble fraction>Cu oxidative fraction>Cu reducible fraction fluctuant and unstable. Fe acid soluble fraction>≈Fe oxidative fraction>Fe reducible fraction.Added Pb or Cu or Pb/Cu together, it showed that Mn acid soluble fraction>Mn oxidative fraction>Mn reducible fraction; Pb reducible fraction>Pb oxidative fraction>Pb acid soluble fraction.(4)On the condition of different water level, the content of Cu, Fe, Mn in iron plaque were affect and.The contents were the most on the water lever of2～3cm, it is illustrated that iron plaque can absorb heavy metal Cu, Fe. Mn. However. Pb was not affected by the water lever of2～3cm.On the water level of2～3cm. the Fe content in iron plaque correlated with the Cu content in iron plaque, the Cu content of acid soluble fraction in soil and the Cu content of reducible fraction.The Fe content in the iron plaque correlate with the Fe content of reducible fraction.,but they didn’t correlate with the Fe content of oxidative fraction and reducible fraction.The Fe content in iron plaque correlated with the Mn content in iron plaque.the Mn content of oxidative fraction and the Mn content of reducible fraction.The Pb content in iron plaque correlated with the Pb content of oxidative fraction.