碱性土壤盐化过程中阴离子对土壤中镉有效态和植物吸收镉的影响  

Impact of inorganic anions on the cadmium effective fraction in soil and its phytoavailability during salinization in alkaline soils

作　　者：王祖伟[1] 弋良朋[1] 高文燕[1] 曾祥峰[1] 王中良[1] 

机构地区：[1]天津师范大学城市与环境科学学院,天津300387

出　　处：《生态学报》2012年第23期7512-7518,共7页Acta Ecologica Sinica

基　　金：国家自然科学基金(40973078;40830746);973计划前期研究专项(2010CB434806);天津市科技计划项目(10SYSYJC27400)

摘　　要：镉是土壤环境中对土壤质量有着极其重要影响的污染物之一,低含量下就能对人体和动物产生危害。镉在土壤中的有效态既决定了它的生物有效性及对环境的危害程度,又是人们对受污染土壤进行治理和修复的基础。作为盐化土壤中的典型组分,无机盐不可避免对镉的有效态及生物有效性等地球化学行为产生明显影响。研究了碱性土壤盐化过程中无机盐阴离子对土壤中镉有效态和植物吸收镉影响。研究方法为:以钠盐为例,实验研究了碱性土壤盐化过程中无机盐阴离子对土壤中镉有效态的影响;通过油菜种植试验,分析了无机盐阴离子对土壤中镉生物有效性的影响。研究结果表明,土壤盐化过程中,土壤溶液中Cl-浓度较低时,土壤中镉的有效态含量随Cl-浓度增加而增大,但当土壤中Cl-/Cd的比值大于100∶1时,土壤中镉的有效态含量达到最大值。土壤溶液中SO24-含量对土壤中镉有效态含量的影响不明显;随着土壤溶液中HCO-3含量的增加,土壤中镉的有效态含量明显减少。由于Cl-、SO24-是土壤溶液中的主要成分,随着盐度的增加,镉的有效态含量增加。油菜种植试验显示,当土壤中Cl-的含量增加时,土壤中镉的有效态含量增加,有利于植物对镉的吸收,因此油菜中镉的含量随土壤中Cl-的含量增加而增加,但当土壤有效态含量超过2 mg/kg后,油菜吸收镉已经达到最大。随着土壤溶液中SO24-浓度的增加,油菜中镉含量基本不变;土壤溶液中HCO-3的含量增加,植物中镉的含量随土壤中HCO-3含量增加而减少。这些特征与土壤镉有效态变化相吻合。通过各种措施控制土壤盐度和调节阴离子类型和含量,有利于降低土壤中镉的有效态含量,减轻镉的活化;农业生产中适当调整无机肥料的种类,可以减少农作物对镉的吸收。Cadmium （Cd） is one of the main heavy metal pollutants in the soil environment. It has an important influence on soil quality and can cause harm to humans and animals at low concentrations. The Cd effective fraction （dissolved ＋ exchangeable ） in soil is important in determining its bioavailability and harmful levels in the soil environment, but it is also the foundation of contaminated soil treatment and remediation. There are many soil factors which influence concentrations of the Cd effective fraction. As a typical component of salinization in soil, inorganic salts inevitably have an obvious impact on the geochemical behavior of Cd in soil such as Cd fractions and their bioavailability. In this paper, the impact of inorganic salt anions such as CI-, SOl- and HC03 on the concentrations of the Cd effective fraction in soil and its phytoavailability wasstudied in order to understand the influence of inorganic salts on Cd geochemistry during the process of salinization in alkaline soils. Using sodium salts as the example, the impact of inorganic anions such as CI-, SO24- and HCO-3 on concentrations of the Cd effective fraction was studied experimentally and the impact of inorganic anions on Cd phytoavailability was studied in a rape cultivation experiment. The Cd effective fraction in soil was extracted using the Tessilar method, and concentrations of the Cd effective fraction in soil and Cd concentrations in rape were measured by Inductively Coupled Plasma Mass Spectrometry. The experiments investigating the impact of inorganic anions on the cadmium effective fraction showed that concentrations of the Cd effective fraction in soil increased with increasing C1- concentration in soil solutions and reached a maximum when the concentration ratio of C1-/Cd exceeded 100 ： 1. For soZ4-, no obvious effect was observed on the concentrations of Cd effective fraction, while increasing HCO3 concentration in soil solutions significantly reduced concentrations of the Cd effective fraction. The rape cultivation expe

关 键 词：碱性盐化土壤 无机盐阴离子 镉有效态 植物有效性 

分 类 号：X131.3[环境科学与工程—环境科学]