Hg在玲珑金矿区典型农田土壤中的吸附特征研究

Absorption of Hg in Typical Farmland Soils in the Linglong Gold Mining Area

采集烟台玲珑金矿区不同性质的土壤,通过吸附解析实验研究了矿区2种典型农田土壤对重金属汞的吸附特征.等温吸附-解吸实验结果表明,酸性土壤对Hg(Ⅱ)的平均吸附率高于中性土壤,中性土对Hg(Ⅱ)的最大吸附量为156.9μg/g,酸性土达到201.38μg/g.2种土壤结合Hg(Ⅱ)的解吸量和解吸率都较低,且酸性土的解吸率(13%)高于中性土(12%).Langmuir方程和Freundlich方程都能较好地描述酸性土对Hg(Ⅱ)的等温吸附过程,相关系数r分别为0.995 6和0.982 6.对于2个拟合方程,2种土壤更适合用Langmuir方程描述,对应的相关系数分别为0.995 6和0.955 9;Hg(Ⅱ)在土壤中的吸附过程可分为开始的快速吸附和随后的慢速吸附2个阶段,快速反应阶段的吸附量和吸附速率均远大于慢速反应阶段.相比抛物线扩散方程,Elovich方程更适合描述2种土壤的动力吸附过程,所得到的相关系数r为0.971 4和0.967 2;pH 3.0～5.5时,Hg2+在土壤中的平衡吸附量呈上升趋势,继续升高到pH 6.5,则最大吸附量降低.

This study focused on the adsorption properties of Hg in 2 typical farmland soils in the Linglong gold mining area in Yantai area of China.The adsorption-desorption of Hg（Ⅱ） research result showed higher adsorption of Hg in neutral soil with the value of 201.38 μg/g than that in acid soil with the value of 156.9μg/g.The desorption of Hg in both soils was low with neutral soil showing a higher desorption ratio（13%） than acid soil（12%）.Hg（Ⅱ） adsorption isotherms were well fitted by Langmuir and Freundlich equation in the acid soil,with the correlation coefficient r value of 0.995 6 and 0.982 6,respectively.Langmuir equation can best describe Hg（Ⅱ） adsorption isotherm in the neutral soil and acid soil,with the r value of 0.995 6 and 0.955 9,respectively.The adsorption was a bi-phasic process which started with a fast-adsorption phase and a slow-adsorption phase.The adsorption amount and rate of Hg in the fast reaction phase were much larger than that in the slow one.The adsorption kinetic can be better fitted by Elovich equation with correlation coefficient of 0.971 4 and 0.967 2,respectively.At pH 3.0-5.5,the equilibrium adsorption amount of Hg（Ⅱ） increased with higher pH,and then decreased when the pH reached 6.5.