Studyonthe Phytoremediation By Sedum Plumbizincicola And Safety Utilization For Cd Contaminated Farmland Soil

Heave metals could be removed from the soil by phytoextractiony environmentally and effectively.The advantages of the remediation Cd-contaminated soils by Cd hyperaccumulator Sedum plumbizincicola have become a public concern.How to proper improve the phytoextraction efficiency and achieve safety production attracted more and more attention.Rapid seedling,improve the remediation efficiency in field experiments and safety utilization of the restored soils were conducted in the Cd contaminated soils.The effects of substrates on the growth of S.plumbizincicola seedlings,fertilizer ratio on Cd remediation efficiency and stabilization on the safety production of Brassia chinensis were studied,which to provide a theoretical basis for the safe and effective production on Cd contaminated soils.The main result are as follows:?1?Using the paddy soils,river sand,perlite and vermiculite as raw materials,seven kind of the substrates with the different proportions of components were conducted for the seedling experiment of S.plumbizincicola and the analysis method of subordinate function and principal component was used to evaluate the pros and cons of different substrates.The results showed that the best growth performance of S.plumbizincicola seedlings was attained in the substrate of T2?river sand?,T4?paddy soil:perlite=1:1,by volume?,T7?perlite:vermiculite=1:1,by volume?,and indicated that T2,T4 or T7 was optimum to be seedling substrate for S.plumbizincicola.The aeration porosity,AP/WHP and pH of the substrates had significantly influence on the growth of S.plumbizincicola.We observed that the aeration porosity of substrates had closely related to the growth of S.plumbizincicola in the AP/WHP range of 0.23⁰.79.?2?An orthogonally designed experiment was conducted to investigate the effects of different N,P and K levels on S.plumbizincicola growth and the uptake of Cd in the field experiment.The results showed that the fertilization promoted the growth of S.plumbizincicola,and increased 33.8%available Cd with decreased soil pH by 0.08⁰.50.Increasing the application N was a slightly beneficial to the absorption of Cd of S.plumbizincicola,while Cd extraction capacity be inhibited after P application.The Cd extraction capacity by S.plumbizincicola were221.61 g/hm² with N₃P₂K₁ treatment.It was indicated that the best treatment was N₂P₁K₂?200 mg/kg N,40 mg/kg P,160 mg/kg K?considering the remediation efficiency.?3?Brassia chinensis was grown in the soils which has been double or triple phytoextraction by S.plumbizincicola after sepiolite and lime amendment.Compared with the control,pot experiments showed that the maximum increase of soil pH was 2.18,2.56 and 2.33,respectively,and the available Cd decreased by 76.2%,77.9%and 68.7%under sepiolite and lime treatment.The Cd concentrations in Brassia chinensis under the treatments combined 2%sepiolite and lime or the single treatments were lower than the Chinese safe standard for cadmium in foods?GB 2762—2012?compared with the unrepaired soils.Brassia chinensis could achieve safety production on the soils of triple phytoextraction by S.plumbizincicola with 2%sepiolite or lime treatment.