不同类型土壤对汞和砷的吸附解吸特征研究

为了探明不同类型土壤对重金属汞和砷吸附、解吸的影响,以性质差异显著的红壤、黑土和潮土为供试土壤,采用批量平衡法,研究了Hg(Ⅱ)和As(Ⅴ)在不同土壤中的吸附-解吸行为。结果表明:(1)Freundlich方程和Langmuir方程均能较好地拟合这3种土壤对Hg(Ⅱ)和As(Ⅴ)的吸附,其中Hg(Ⅱ)的最大吸附量分别为451.33、1699.46和1635.21mg/kg,大小顺序为黑土>潮土>红壤,相关系数(R2)在0.8533～0.9911之间;As(Ⅴ)的最大吸附量分别为818.44、561.87和112.77mg/kg,大小顺序为:红壤>黑土>潮土,相关系数(R2)在0.9223～0.9949之间;而线性方程则不能较好地拟合这3种土壤对Hg(Ⅱ)和As(Ⅴ)的等温吸附。(2)Hg(Ⅱ)和As(Ⅴ)的解吸量随Hg(Ⅱ)和As(Ⅴ)吸附量的增加而增加,两者之间呈显著或极显著的线性正相关,Hg(Ⅱ)的相关系数(R2)分别为0.8668**、0.8971**、0.9969**,As(Ⅴ)的相关系数(R2)分别为0.9987**、0.9964**、0.9858**。研究结果对于探明土壤中汞和砷的环境行为具有重要意义。

MERCURY AND ARSENIC ADSORPTION-DESORPTION BEHAVIORS IN THE DIFFERENT SOILS

In order to illustrate the behavior of adsorption and desorption of heavy metals such as mercury(Hg) and arsenic(As) on soils,three different soils including red soil,black soil and fluvo-aquic soil were applied in the present paper.Adsorption-desorption of mercury and arsenic on these three soils were studied by the method of batch equilibrium experiments.Results showed that Freundlich model and Langmuir model fit adsorption of mercury and arsenic on three soils.The maximum adsorption amounts for mercury were 451.33mg/kg,1699.46mg/kg,and 1635.21mg/kg for red soil,black soil,and fluvo-aquic soil,respectwely.Their correlation coefficient(R2) ranged from 0.8533 to 0.9911.The maximum adsorption amounts for arsenic were 818.44mg/kg,561.87mg/kg and 112.77mg/kg for red soil,black soil,and fluvo-aquic soil,respectively.Their correlation coefficient(R2) ranged from 0.9223 to 0.9949.However,the linear model couldn’t be used to fit mercury and arsenic isothermal adsorption on three soils tested.(2) The desorption amounts of Hg(Ⅱ) and As(Ⅴ) increased with the increases of the adsorption amount of Hg(Ⅱ) and As(Ⅴ) on the three soils increasing.Significant linear correlation was found between desorption and adsorption amount of Hg(Ⅱ) and As(Ⅴ),the correlation coefficients(R2) for Hg(Ⅱ)were 0.8668**,0.8971**,0.9969**,and the correlation coefficients(R2) for As(Ⅴ)were 0.9987**,0.9964**,0.9858**.All the results showed important significance for illustrating environmental fates of mercury and arsenic in soil.