Cd/Zn 及Cd /Zn/Ni复合污染对胡萝卜生长吸收特征的影响

利用盆栽试验对胡萝卜在不同浓度Cd/Zn及Cd/Zn/Ni复合作用下的重金属吸收效应进行了研究。结果表明，在Cd/Zn/Ni和Cd/Zn复合污染条件下，胡萝卜茎叶和块茎干重与对照土壤比较均受到显著影响（P＜0.05），尤其是含Ni组合，在Ni浓度达到250 mg·kg-1后，胡萝卜块茎和茎叶生物量都锐降（P＜0.01）。对比不同剂量下两组合富集系数（EF）和转运系数（TF）的结果发现，含Ni组合中， Cd、Zn、Ni 3种重金属在不同迁移界面以及不同浓度水平时的活性不同：在土壤-胡萝卜块茎迁移界面，当土壤中Cd、Zn、Ni浓度分别在0.35～1.8、50～300 mg·kg-1以及60～250 mg·kg-1之间时，活性大小为Cd〉Zn〉Ni；当其浓度分别达到3.5 mg·kg-1（Cd）、600 mg·kg-1（Zn）以及500 mg·kg-1（Ni）时，活性大小变为 Zn〉 Ni 〉Cd ；而在胡萝卜块茎－茎叶界面，Cd的活性在任何浓度水平下始终最大，当Zn、Ni浓度分别在50～180 mg·kg-1以及 60～170 mg·kg-1之间时，活性大小为Zn＞Ni ,但在此浓度之后Ni的作用突显，活性大小变为Ni＞Zn。非含Ni组合中，在两迁移界面和不同浓度水平下，两种重金属的迁移能力始终为Cd＞Zn。此外，在碱性较高的绿洲灌淤土中，Cd、Zn、Ni之间的交互作用表

Growth and Absorption Responses of Carrots to Cd/Zn and Cd/Zn/Ni Stress

A pot experiment was conducted to observe the effects of the bioavailability and uptake of heavy metals in different parts of carrots. This research tested 2 different combinations of heavy metals Cd/Zn/Ni and Cd/Zn. For each combination 8 different concentration scenarios were tested. The results showed that carrots＇shoots and roots biomass were affected significantly （P〈0.05） by the Cd/Zn/Ni and Cd/Zn cocontamination combinations.For the Cd/Zn/Ni combination, all tissues of the carrots decreased sharply （P〈0.01）when the concentration of Ni reached 250 mg·kg-1. This result exhibited Ni significant influence on carrots＇growth. The calculated transfer ratio from roots to soil（EF） and the transfer ratio of shoots to roots （TF） showed that the activity level（ or bioavailability ） of these heavy metals varied with the concentration of the co-contaminant combination within the soil. For the Cd/Zn/Ni combinations with concentrations of 0.35〈Cd〈1.8 mg·kg^-1, 50〈 Zn〈300 mg·kg^-1 and 60〈Ni〈250 mg·kg^-1, Cd was the most bioavailable in the soil-roots interface. Zn was the next most bioavailable followed by Ni, i.e. in terms of bioavailability Cd〉Zn〉Ni. At a different concentration of the co-contaminants in the soil-roots interface, 3.5 mg·kg^-1 Cd, 600 mg·kg^-1 Zn and 500 mg-kg-lNi, the bioavailability followed this order Zn〉Ni〉Cd. While in the roots-shoots interface, the bioavailability was from greatest to least Cd〉Zn〉Ni at concentrations of 0.35〈Cd〈 1.25 mg·kg^-1, 50〈Zn〈 180 mg·kg^-1 and 60〈Ni〈 170 mg·kg^-1, but at higher concentrations for each heavy metal the bioavailability followed this order Cd〉Ni〉Zn. For co-contamination with the Cd-Zn combination, the bioavailability of these two heavy metals was always Cd〉Zn at all concentrations and interfaces. In addition, the interactions between Cd, Zn, and Ni were observed. Cd and Ni acted antagonistically and Zn and Ni acted synergistically with regards to uptake.