| As is well known, the quality and safety of agricultural products is closely related to theorigin of soil. Heavy metal contamination of agricultural land not only led to the decline in thefarmland soil quality, but also affected plant growth, human health and life safety through thefood chain.Therefore, agricultural land soils heavy metal pollution had become an importantenvironmental issue needed to be solved.In this thesis, we focused on soil cadmium (Cd) and antimony (Sb) pollution through thepot experiment of varying degrees of soil Sb pollution on cole growth and enrichment of Sb. Atthe same time, phytohormone, indole-3-acetic acid (IAA) and gibberellic acid (GA3), wereintroduced into phytoremediation, in combination with the biodegradable chelating agentnitrilotriacetic acid and ethylene diamine disuccinic acid, to replaced the ethylene diaminetetraacetic acid (EDTA). Aimed to submit certain assess at the technolgy of enhancedphytoremediation, another pot experiment was conducted to study enhanced phytoremediationefficiency in the removal of cadmium from contaminated soils with chelating agent andphytohormone. The main original innovations of this work were summarized as follows.(1) It was indicated that Sb at a low concentration could promote growth, while highconcentration of Sb is poisonous to plant. The maximum value of cole transfer coefficient couldreach9.608, when the concentration of Sb was low. With the increase of concentration, coleshowed certain tolerance of Sb, depending on the ability of imposing restrictions on rootabsorbtion and transfer to acrial part of plant to alleviate toxic effects of Sb.(2) The extraction and transfer of Cd was effectively enhanced by chelating agent, withthe promote effect: NTA> EDDS. Under the influence of chelating agent, the maximum value oftransfer coefficient reached1.228, which showed property of hyperaccumulator. The mosteffective accumulation concentration of Cd in underground parts and aerial parts of plant were1220.558and95.318mg/kg, respectively, in which compared with control treatment increasedby96.83%and32.77%.(3) Growth of Cd metal-stressed plants and the extraction of Cd were significantlypromoted by phytohormone. In comparison with contrast treatment, under the condition of15mg/kg Cd, the highest accumulation concentration of Cd in underground parts increased by98.17%, while under the condition of55mg/kg Cd, the top accumulation concentration of Cd in aerial parts increased by159.43%.(4) It was observed that the application combined phytohormone with chelating agentscould availably alleviate toxic effects of Cd and significantly increased Cd extraction efficiency,and the effect performed as, at the same treatment with chelating agent, GA3> IAA, while at thesame treatment with phytohormone, NTA> EDDS. In comparison with contrast treatment, thehighest accumulation concentration of Cd in underground parts was markedly increased by128.58%at15mg/kg Cd, while the high-point of Cd accumulation concentration in aerial partswas notablely improved by162.56%at55mg/kg Cd.The potential of cole applied to phytoremediation with mild-to-moderate Sb pollution inreclamation area was shown. And there would be vast prospect for future development, withadded by some appropriate measures to enhance the removal of Sb polluted soil. Theexperiments indicate that phytohormone in combination with chelating agents can increase thebiomass of metal-stressed plants, enhance the capacity of heavy metal accumulation, andimprove the phytoextraction potential of these plants. These work provided an effectivetheoretical foundation for enhanced phytoremediation, and had some definite instruct meaningon the problem of phytoremediation application. |
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