Accumulation Characteriacter Of Heavy Metals In Field Rape And Flax And The Subsequent Treatment

Phytoremediation is an effective method to control heavy metal pollution in farmland.However,a large amount of harmful biomass will be produced after harvesting the restored plants,which will cause secondary pollution to the environment.How to dispose of these harmful biomass also becomes an urgent problem to be solved.In this study,heavy metal contaminated farmland in huanggu village was planted with rape and flax,to study the remediation of local farmland soil contaminated by heavy metal.The best extraction conditions for detoxification of seed cake were determined by extracting oil from the seeds of rape and flax and detoxification of seed cake by hydroenzymatic method and hydrochloric acid extraction.The main goal of this study is not only to remove heavy metals by rape and flax from the soil,but also to remove the heavy metals from the meal cake,turning waste into treasure for the remediation of heavy metal pollution in soil to provide new solutions and ways to make phytoremediation technology efficient and sustainable development.It is integrant to dispose seed meal which is a secondary product after phytoremediation in a appropriate modus.This study showed the following:(1)rape and flax both have a high ability to accumulate heavy metal,especially for Cd.The bioconcentraction factors(BCF)of Cd in rape leaves and flax leaves were more than 7.Rape and flax are both crops with large biomass,and the biomass per hectare can reach more than 11,000 kg.(2)The oil extraction rate of Aqueous Enzymatic Method can reach nearly 50%.Aqueous Enzymatic Method can remove a large amount of heavy metals from seed cake at the same time of oil extraction.The concentrations of Pb,Zn,Cu,Cd in rape seed meal is 1.02 mg/kg、28.11 mg/kg、3.22 mg/kg、0.17 mg/kg,respectively,after extracted by Aqueous Enzymatic Method.(3)Removal rate of heavy metals by hydrochloric acid was increased by raising the extractant concentrations,or temperature,or liquid-solid ratio,or reaction time.The lowest concentrations of Pb,Zn,Cu,Cd in rape seed meal is 0.72 mg/kg,11.39 mg/kg,1.31 mg/kg,0.05 mg/kg,respectively.And the lowest concentrations in flax seed meal is 3.51 mg/kg,16.5 mg/kg,4.97 mg/kg,0.29 mg/kg,They all met the standard of Hygienic standard for feeds(GB13078-2001).Therefore,both methods can be used to deal with the remaining seeds produced after phytoremediation,which can not only prevent secondary pollution,but also can be recycled.