| Cadmium(Cd) pollution resulted from industrial production such as mining, smelting, electroplating, agricultural activities such as sludge irrigation and fertilization and atmospheric sedimentation, which has aroused public concern in the last few years. Due to its strong mobility, high toxicity, non-degradability and easy to concentrate in plants and animals through food chains, Cd can cause various diseases to plants, animals and even human beings. Now therefore, the remediation and abatement of Cd-contaminated soil are of great importance for global sustainable development.Phytoremediation, the use of green plants to extract, sequester and detoxify pollutants, has always been described as an economical, safe and eco-friendly alternate technology. It revolutionized phytoremediation technology by utilizing chelating agents to activate heavy metals in soil, facilitate the heavy metals accumulation and translocation in plant and then enhance the phytoremediation efficiency. Boehmeria nivea(L.) Gaud is one of the best plant fibers for textile in the south of China. It has fast growth, high bio mass, wide distribution, strong tolerance to drought and barren, high economic value, as well as certain endurance to Cd stress, which makes it a good candidate for repairmen of Cd contaminated soils, and potential to apply in remediating soils and water w ith Cd pollution, the ecological restoration of abandoned mine tailings.In this study, we selected ramie as the goal experimental plant, Cd as goal contaminant and biodegradable NTA and CA as the exogenous additives, chose pot experiments to study the tolerance, accumulation and uptake of ramies under Cd stress, aiming to investigate the effects of NTA and CA on soil Cd solubility, Cd phytotoxicity in and ramie, and Cd accumulation in different ramie tissues.At the same time, studied its application to phytoremediation and supplied scientific evidences and theoretical basis the application of phytoremediation technology to treat soils polluted by Cd.The major content and results were summarized as follows:1 Soil cultured experiments were carried out to st udy the enrichment abilities and physiological response of ramie(Bechmeria nivea(L.) Gaud) at different concentration of Cd(0, 5, 10, 25, 50, 100 mg/kg). The results of the study showed as follows: With the increase of Cd concentration, the biomass, roo t activity expressed upward trend firstly and then downward; With the increase of Cd concentration, The activities of superoxide dismutase(SOD), peroxidase(POD) and the content of malondialdehyde(MDA) increased remarkably, but the activities of catalase(CAT) decreased under the Cd stress; The concentration and accumulation of Cd in ramie increased with the increase of the concentration of applied Cd, and the maximum amount of Cd concentration and accumulation could reach up to 86.1mg/kg and 371.9 ug/plant, while the concentration of applied Cd achieved 100mg/kg, respectively. The translocation factor(TF) < 1 and the metal extraction ratio(MER)?0.1% suggested most of the Cd taken up by ramie accumulated in roots and ramie has great stabilization ability.2 Pot experiments were carried out to investigate the influence of citric acid(CA) and nitrilotriacetic acid(NTA) levels(0, 1, 5, 10 mmol/kg) on the ramie biomass, malondialdehyde(MDA) content, antioxidant enzyme activities of shoot, accumulation of cadmium(Cd) in ramie when exposed to Cd(10mg/kg) and Cd(50mg/kg). The results demonstrated that CA and NTA promoted ramie growth and increased Cd uptake in ramie. CA promoted ramie growth and increased Cd accumulation in ramie, but showed no significant effect on Cd transfer. Application with NTA increased Cd uptake and transfer in ramie, and also contributed to phytoextraction of Cd. The activities of CAT, SOD, POD and the content of MDA indicated that CA and NTA relieved oxidative stress and damage of r amie by Cd stress. Overall, exogenous chelates CA and NTA are beneficial for phytoremediation of Cd-contaminated soil. |
PDF Full Text Request