不同生长时间苋菜对土壤中镉的富集特性OA

With heavily Cd-contaminated soil from Liuyang City,Hunan Province,and Amaranthus tricolor L.(red round-leaf amaranth)used as materials,field and pots experiments were conducted to characterize Cd accumulation by amaranth and evaluate the effects of amaranth cultivation on soil Cd content and speciation.In the field,plots without amaranth were used as controls,and amaranth was grown for 15,30,45,and 60 days to compare Cd accumulation among roots,stems,and leaves across growth durations.In plots,we monitored changes in total Cd(w),available Cd,and chemical fractions following amaranth cultivation.The results showed that Cd concentrations differed among plant organs and were consistently highest in roots.The bio-concentration factor(BCF)for Cd followed in the decreasing order in root,leaf,and stem.BCF values in all organs increased initially and then declined,peaking at 45 days(roots 26.61,stems 18.05,leaves 21.85).Across the four growth durations,the stem translocation factor(TF)for Cd did not vary significantly,whereas the leaf TF increased over time,indicating progressive Cd translations within plants toward leaves.In the pot experiment,total soil Cd(w)under amaranth cultivation was 2.96 mg∙kg-1,significantly lower than the 3.15 mg∙kg-1 in the unplanted control.Amaranth cultivation also significantly reduced soil available Cd,increased the acid-soluble Cd fraction,and decreased the residual Cd fraction,indicating both a reduction in the soil Cd mass fraction and a shift in Cd speciation.Overall,A.tricolor L.can grow in heavily Cd-contaminated soil and effectively accumulate Cd.