Cd Repairing Performance And Strengthening Measures Of Celosia Argentea Linn. For Phytoremediation Of Cd-contaminated Soil

Cadmium?Cd?is considered to be one of the most toxic heavy metals and it is also one of the main heavy metal pollution.Therefore,treatment of Cd contaminated soil has become a major issue to be solved in the current.Compared with the traditional physical and chemical methods to remedy heavy metals contaminated soil,phytoremediation of heavy metal Cd in contaminated soil by hyperaccumulators has the advantages of simple operation,economy and technology to the implementation of a large area,will cause two pollution and other advantages to the repair area,has a broad application prospects in remedy heavy metals contaminated soil.But at present,there are fewer species of Cd hyperaccumulators be found at home and abroad,hyperaccumulators have the defects of low biomass,slow growth and weak environmental resistance under natural conditions.It is difficult to be applied to the rapid remediation of heavy metal contaminated soil,which limits the efficiency of phytoremediation.Therefore,hyperaccumulators screening and enhancement effect is the foundation and the core problem of heavy metal contaminated soil plant extraction and remediation and also is the difficulty of phytoremediation of polluted environment.Our research group has a field investigation in Daxin Manganese Mine in Guangxi,found a Amaranthaceae annual herb—Celosia argentea Linn..It can grow abundantly in heavy metal environment that exceed the standard.The experimental results show that Celosia argentea Linn.has strong tolerance in the single Cd pollution soil and has a higher BCF.For that reason,on the basis of this research we study on remediation of soil Cd by C.Argentea and use a series of studies on different measures to strengthen C.argentea remediation of Cd contaminated soil.Following is major results of this paper:?1?The Cd content in C.argentea leaves in water-soluble Cd compound was up to 208mg·kg^-1 by Cd SO₄.Leaves of C.argentea accumulation of water-insoluble cadmium content with the Cd?OH?2,Cd S,Cd CO3 and Cd O enrichment of content reached 134,102,100 and 90.2 mg·kg^-1,respectively.This shows that in different chemical states of C.argentea Cd had stronger enrichment ability.This characteristic can greatly improve the efficiency of phytoremediation of Cd contaminated soil.?2?Light Cd stress(1¹5 mg·kg^-1)can promote C.argentea seed germination energy,germination percentage and germination index and vigor index.A pot experiment was conducted to study on Cd get rid of the apical dominance of C.argentea.It showed that the number of leaves and collars increased significantly,and the increase of biomass and the increase of total transpiration in the shoots of C.argentea could be improved.The increase of transpiration increased the transport of cadmium to the aerial parts,and increased the accumulation of cadmium on the aerial parts of C.argentea.Therefore,the removal of the top edge is a highly efficient way to improve plant remediation of heavy metal contaminated soils.?3?As soon as possible in order to be able to apply research results to practical soil heavy metals pollution treatment.This research through the static absorption of pot experiment and use tailings pollution soil as the research object.We found that the total Cd content of farmland soil is 5.72 mg·kg^-1.This final value is below the artificial addition of the same Cd concentrations of Cd uptake.Thus addition citric acid?CA?,malic acid?D-MA?,oxalic acid?OA?,tartaric acid?TA?,EDTA,humic acid?HA?and sodium dodecyl benzene sulfonate?SDBS?which concentration is 1,2.5,5,8,10 and 15 mmol·kg^-1 as analytical enhancer for soil Cd.When concentration enhancer concentration is 5 mmol·kg^-1 makes leaves of C.argentea has a large numerical value,it is 2.72 times times that of control group.From the experiment and the security considerations,we can optional application 5mmol·kg^-1 CA can significantly strengthen the C.argentea capacity of absorption and accumulation effect by actual heavy metals contaminated soil.?4?Through C.argentea on Cd pollution farmland soil that accumulative kinetics experiment,C.argentea on Cd accumulation increased with time but in the 8th to 12 th weekthe accumulation of Cd in the aboveground part was not significant?p>0.05?.In the 8th to12 th week,C.argentea on the amount of enrichment of Cd growth cycle reaches the maximum value.From this judgment,is the 8th week of C.argentea good time to harve.?5?To enrich the basic theory of C.argentea on Cd tolerance of histology,this research uses the Cd concentration of 10 mg·kg^-1 Cd Cl2 for Cd source after 50 d,the plant as the experimental material.Observation under Cd stress,the changes of cell structure in root,stem and leaf in Cd-contaminated pollution condition or non-pollution condition.We found when Cd concentration is 10 mg·kg^-1,its organization did not change significantly.This experiment indicates that the Cd did not destroy plant's normal tissue.This experiment shows that under Cd stress C.argentea has maintain the stability of good organizational form.