| 污灌区盐分累积对土壤汞吸附行为影响的模拟研究 |
| 摘要点击 2311 全文点击 1517 投稿时间：2013-08-03 修订日期：2013-12-18 |
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| 中文关键词 汞 盐渍化 NaCl Na2SO4 吸附 土壤 |
| 英文关键词 mercury salinization NaCl Na2SO4 adsorption soil |
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| 中文摘要 |
| 以受盐渍化和重金属汞双重胁迫的天津污灌区土壤为研究对象，探讨汞在盐渍化土壤中吸附的热力学及动力学特征. 研究的盐分种类为污灌区土壤盐渍化进程中的主要盐分NaCl和Na2SO4，设置的盐度梯度为7个，添加质量分数为0~5%. 结果表明，Lanmguir方程和Elovich方程可以理想地拟合盐处理下土壤对Hg（Ⅱ）吸附的热力学和动力学过程. 当加入的盐分为NaCl时，随着添加盐度的增长（0~5%），最大吸附量（Langmuir方程的参数qm）、吸附强度（Langmuir方程的参数k）迅速降低，分别由对照的868.64 mg·kg-1和1.32减少至添加5% NaCl的357.48 mg·kg-1和0.63，且使土壤Hg（Ⅱ）的吸附速率（Elovich方程的参数b）显著下降；当加入的盐分为Na2SO4时，随着盐度的增长，最大吸附量和吸附强度小幅下降，由对照降低至添加5% Na2SO4的739.44 mg·kg-1和1.18，对土壤Hg（Ⅱ）吸附速率影响不显著. 土壤中Cl-和SO42-含量对Hg（Ⅱ）最大吸附量之间可以用对数模型刻画，Cl-含量与Hg（Ⅱ）吸附速率之间表现为线性关系. 研究表明，高浓度的NaCl环境极其不利于Hg（Ⅱ）在污灌区土壤中的吸附及固持，用含NaCl较高的污水灌溉作物很有可能会引起汞的二次污染，土壤的盐渍化趋势会使汞污染和释放趋势更趋严重. |
| 英文摘要 |
| This study was designed to pinpoint the impact of salinity (NaCl and Na2SO4, added at salinity levels of 0-5%, respectively) on the adsorption behavior of mercury in wastewater-irrigated areas of Tianjin City by batch and kinetic experiments. The results showed that, the Langmuir isotherm and the Elovich equation can well fitted batch and kinetic experimental data, respectively. As NaCl spiked in soil, Hg(Ⅱ) adsorption capacity and strength had marked decreases, from 868.64 mg·kg-1 and 1.32 at control to 357.48 mg·kg-1 and 0.63 at 5% salinity level of NaCl, respectively. As Na2SO4 spiked in soil, Hg(Ⅱ) adsorption capacity (parameter qm in Langmuir isotherm) and strength (parameter k in Langmuir isotherm) changed slightly, from 868.64 mg·kg-1 and 1.32 at control to 739.44 mg·kg-1 and 1.18 at 5% salinity level of Na2SO4, respectively. Kinetic data showed that, Hg(Ⅱ) adsorption rate (parameter b in Elovich equation) in soil was not influenced by Na2SO4 addition. However, the addition of NaCl had a great effect on mercury adsorption rate. Hg(Ⅱ) adsorption capacity as a function of Cl- or SO42- content in soil could be simulated by the natural logarithm model, while Hg(Ⅱ) adsorption rate as a function of Cl- content in soil could be simulated by the linear model. The study manifested that NaCl can significantly increase migration of Hg(Ⅱ) in the soil irrigated with wastewater, which may enhance Hg(Ⅱ) bioavailability in the soil and cause a hazard to surface water. Especially, it will be harmful to human body through the food chain. |
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