Long-acting Study On The Absorption And Passivation Of Cadmium-contaminated Acid Red Soil Plants

Control of heavy metal pollution of farmland soil has two ideas: one way is the direct removes heavy metals from the soil,reducing the total amount of heavy metals and remediating soil fundamentally;the second way is to reduce the concentration of the effective state of heavy metals in soil and biological effectiveness,reducing the crop absorption of heavy metals.Based on this,developed based on the plants accumulation of heavy metals to phytoextraction technology and stabilizer to passivation repair technology.This study by the cadmium pollution of acid red soil as the research object,on the basis of early research,continue to evaluate the repair efficiency of the field Sedum plumbizincicola and the safety of the subsequent crops,continue to explore the persistence of the stabilization;compare the effect of the different concentration of potash on the growth the cadmium/ zinc absorption and of Sedum plumbizincicola through the pot and field experiments to at the same time.The research provides theoretical basis and technical support for efficient repair and effect evaluation of cadmium pollution farmland.Restoration demonstration base is located in Xiangtan county of Hunan province,the planting area of Sedum plumbizincicola is about one hectares and a total of 11 field in 2016.The monitoring results show that,by 2016,there is one to three times for planting and harvesting Sedum plumbizincicola each field effective in demonstration fields,the scope of the biomass of Sedum plumbizincicola were1.8~3.1t hm-2,the aboveground biomass reduced gradually compared with 2014 and 2015 years.The scope of cadmium and zinc of Sedum plumbizincicola were 30.4~70.1?1872~3849 mg kg-1,respectively.The cadmium concentration of the soil which repaired for three times decreased from 0.64 by not repair,down to 0.27 mg kg-1,which was below the national secondary standard of soil environmental quality(0.3mg kg-1),the reduction efficiency of cadmium in soil reached 57.8%,but the concentration of the effective state of cadmium concentration is on the rise,there was little effect on the cadmium absorption of Sedum plumbizincicola for different ways of planting.The cadmium concentration of nine kinds of local rice which planted in the standard soil connot produce safely.The results of long-term study on the field test of passivation repair showed that the soil pH was stable in the early and late season of2016(passivation repair of three seasons and four seasons),and the Cadmium concentration of the soil which treat with sepiolite and lime passivation maintain the standard level,while the low passivation treatment of the fourth quarter of brown rice appears excessive cadmium phenomenon.In addition,the results of potash test demonstrated that the effect of potassium fertilizer(96?193?386 mg kg-1)on cadmium absorption was not significant,but the field dry weight could be increased under field test condition.