| With the rapid development of industrialization and urbanization, more and more heavy metals are transferred into the natural soil. The heavy metal pollution will cause a great harm to the environment and humans, because of it is stable and cannot be degraded, able to be biological enriched through the food chain as well, Therefore, it is necessary to repair of heavy metals pollution. Phytoremediation becomes a research hotspot as its advantages of low cost, green sustainable. However it will inevitably exists some limitations, such as low biomass, enrichment and transfer ability of heavy metals of plants. Thus the key to the widely use of phytoremediation is to find some ways that could improve those limitations. In this paper, two subjects of plants were used, the one was tobacco(solanaceae), the other was rush(juncaceae), to research the effects of direct current electrical fields(DC) on growth, enrichment, and transfer ability of heavy metal cadmium of plants, and finally to explore the feasibility of DC to improve phytoremediation. Reached the following conclusions:1) The application of DC have a different influence on plant growth of tobacco and rush. DC can significantly improve the fresh weight, height and biomass(dry weight) of two different subject plants, and with the increase of DC, it will inhibit the growth and development of plants. For the tobacco, the fresh weight, biomass, root length and height reach the maximum in U15, is 1.98 g、0.21 g、10.84 cm and 18.98 cm respectively, and reach the minimum in U35 or U45, is 1.32 g、0.12 g、5.23 cm and 10.68 cm respectively. For the rush, the height and biomass reach the maximum in U25, is 20.05 cm and 01.14 g respectively, and reach the minimum in U45, is 13.34 cm and 0.07 g respectively.This shows that for the tobacco, the optimum voltage is 15 V, that is 0.60 V/cm; For the rush, the optimum voltage is 25 V, that is 1 V/cm.2) The application of DC have a different influence on translocation factor(TF) and bioconcentration factor(BCF) of plants. The tobacco TF in U15(1.6)、U25(1.7)、U35(3.4) and U45(3.5) are increase significantly compared to the control(1.1); the BCF in U5(53.6)、U15(51.3)、U25(40.7)、U35(51.9) and U45(47.5) are decrease significantly compared to the control(58.7). the rush TF in U15(2.0)、U25(1.9) are increase significantly compared to the control(1.5), and TF in U35 is decrease significantly compared to the control; the BCF in U15(0.5) and U25(0.6) are increase significantly compared to the control(0.4).This shows that the application of DC can improve the ability of transfer and accumulate heavy metal for tobacco and rush, and the influence of tobacco and rush are different.3) The application of DC effects the total cadmium in plants. For the tobacco, the total cadmium in shoot and root in U15 reach the maximum, is 233.57 μg and 23.67 μg respectively, and increase significantly compared to the control(shoot 170.18 μg, root 11.20 μg), but the total cadmium in shoot and root in U45 reach the minimum are 97.38 μg and 3.57 μg respectively, and decrease significantly compared to the control. For the rush, the total cadmium in shoot and root in U25 reach the maximum are 2.08 μg and 0.19 μg respectively, and increase significantly compared to the control(shoot 0.95 μg, root 0.14 μg), but the total cadmium in shoot and root in U45 reach the minimum are 0.68 μg and 0.10 μg respectively, and decrease significantly compared to the control.This shows that the application of DC can improve the ability of transfer and accumulate heavy metal for tobacco and rush, and the influence of tobacco and rush are different. Furthermore the total cadmium in plants decreases significantly in the high DC.4) The current time can also effects rush growth and the ability of transfer and accumulate heavy metal. When the DC is 1 V/cm, the biomass, height and the total cadmium of rush reach the maximum in T8, is 0.12 g, 20.05 cm, 270.19 μg(shoot 2.08 μg, root 0.19 μg) respectively, and increase significantly compared to the control T0, however the TF and BCF of rush reach the maximum in T12, is 2.0 and 0.6 respectively, and increase significantly compared to the control.This shows that the optimum current time of rush is 8~12 h/d when the DC is 1 V/cm. |
PDF Full Text Request