| Mercury?Hg?,a non-essential element in the human body,with highly neurotoxic and teratogenic,has been listed as a priority pollutant by the Environmental Protection Agency.Mercury pollution was responsible for minamata disease in Japan in the 1950s and seeds in Iraq in the 1970s.Mercury is also one of the targeted pollutants of the comprehensive prevention and control of heavy metal pollution during the 12th five-year plan.China is rich in mercury resources.Different mercury pollutants will be produced during the process of mercury mining and industrial production.With the effects of atmospheric sedimentation and surface runoff,soil mercury pollution could be a prominent problem,which poses potential harm to organisms.The treatment of mercury in soil is a looming threat to people all over the world.Phytoremediation with green and environmentally friendly has been received significant attention for treatment of mercury in soil.Recently,our research group found that Pteris vittata L.,which grows in the wasteland of typical mercury mining areas,has a strong tolerance and enrichment of mercury.This finding provides a new horizon for mercury soil pollution being repaired,and in-depth exploration of the mercury-rich mechanism of Pteris vittata L.which is an important prerequisite for its future remediation of soil.Therefore,using Pteris vittata L.as the research object,potted planting experiment in the greenhouse were studied to explore the cumulative characteristics and response mechanism of Pteris vittata L.from the angle of plant organs and subcellular by the same concentration of different species of mercury?Hg I2?Hg Cl2?Hg S?Hg?NO3?2?and different concentrations of Hg Cl2(0?1?10?100?500 mg·kg-1).The results are as follows:1.The characteristics Mercury cumulation in Pteris vittata L.with mercury stressThe cumulation and transfer ability of Pteris vittata L.appeared evident difference under different kinds of mercury.It showed that Pteris vittata L.was more resistant to mercury.Meanwhile,up-ground of Pteris vittata L.had the highest total mercury?THg?content and the highest mercury enrichment capacity?BAF??except CK?.The down-ground part of Hg I2 treatment group had the highest THg content and the highest BCF content.The TF was strongest in the Hg S treatment group.With the stress of different concentrations of mercury,THg content in the up-ground and down-ground parts of Pteris vittata L.gradually increased with the increase of soil mercury concentration.Meanwhile,with the increase of mercury concentration in soil,BAF and TF gradually decreased except CK,while BCF was increased gradually,indicating that Pteris vittata L.has stronger cumulation and transfer ability in up-ground part when the mercury concentration is low and stronger cumulation ability in down-ground part when the mercury concentration is high.2.Effects of Pteris vittata L.on soil mercury speciationWith the treatment of different types of mercury,Pteris vittata L.had high removal efficiency of THg during the treatment of Hg Cl2 group.The content of bioavailable mercury in the soil could be reduced by planting Pteris vittata L..And the content of bioavailable mercury in the Hg Cl2 treatment group was reduced the most?about 100.22 mg?,indicating that Pteris vittata L.could absorb bioavailable mercury in the soil more easily during this condition.With the disposal of Hg Cl2,Hg S and Hg?NO3?2,the proportion of mercury content in soil residues had increased,which can reduce the risk of soil mercury pollution.The removal efficiency of THg had increased with the increase of mercury concentration in the soil indicating that Pteris vittata L.can remove mercury effectively from the soil.Mover,Pteris vittata L.could also change the content of bioavailable and residual mercury in the soil.And the 10mg·kg-1 Hg Cl2 treatment group had the best optimal results which had the most reduction of bioavailable mercury and increase of residual mercury,indicating that Pteris vittata L.had the largest utilization degree of bioavailable mercury in the soil and the conversion amount of residual mercury,which was most conducive to reducing the risk of soil mercury pollution.3.The distribution of subcells in the Pteris vittata L.THg content of subcells in the grassland and underground of Centipede under mercury stress was as follows:cell wall>cytoplasm>organelles.There was no significant difference of the content of subcells which is treated by different kinds of mercury group in the up-ground of Pteris vittata L..However,with the treatment of Hg I2,Hg Cl2 and Hg?NO3?2,the THg content in the cytoplasm of down-ground parts was relatively high.With the increase of mercury concentration in soil,THg content of each subcell of Pteris vittata L.showed a trend of gradual increase of cytoplasm and gradual decrease of cell wall. |
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