干旱区绿洲土壤Cd-Zn复合污染下重金属形态及其生物有效性的研究

通过模拟基于Cd-Zn复合污染下干旱区绿洲土壤的胡萝卜盆栽试验,用Tessier连续提取法对胡萝卜土壤中Cd、Zn的形态分布进行分析,同时就生物利用性形态的变化研究了Cd、Zn的生物有效性。结果表明:1)原状土壤中Cd和Zn主要以残渣态存在,随着复合胁迫浓度的增加,Cd的主要赋存形态逐步转变为碳酸盐结合态和可交换态,Zn主要赋存形态逐步转变为以铁锰氧化态和残渣态,但有效态和潜在有效态的比例大大增加。2)胡萝卜对Cd、Zn的富集作用均为地上部分大于地下部分,对Cd的富集能力远远大于Zn。3)胡萝卜吸收的Cd和Zn不仅包括可交换态和碳酸盐结合态,还包括了在一定条件下释放出来的铁锰氧化态和有机结合态。

Chemical forms and bioavailability of heavy metals in the arid oasis soils polluted by Zn and Cd

Pot experiments were conducted based on the arid oasis soils polluted by Zn and Cd,and using Tessier sequential extraction procedure to extract different chemical forms of soil to analyze their distribution is the soil and bioavailability of the heavy metals in soil planted carrot.The study showed that(1)Cd and Zn mainly existed in residual form in the undisturbed soil,but with the increase of Cd and Zn treatment concentration,Cd mainly existed in carbonate form and exchange able form,Zn mainly existed in ferric-manganese oxidation form and residual form,soil microelements-available and potential Cd and Zn was increased.(2)The concentrations of Cd and Zn in above-ground were all higher than that in roots,the carrot showed high accumulation abilities of Cd than Zn.(3)The heavy metals absorbed by carrot included not only exchangeable and carbonate forms,but also ferric-manganese oxidation form and organic combination forms which can be released under certain conditions.