砷、汞在水位波动带中迁移转化规律的试验研究

Experimental study on the migration and transformation patterns of arsenic and mercury in water level fluctuation zone

摘要

【目的】对污染物在地下水位波动带中迁移转化规律的认识是探究地下水污染根源的重要突破口。【方法】以地下水溶质运移理论为基础，通过进行水位波动下的土柱模拟试验，分析了水位波动带中砷、汞在不同水位波动幅度(ΔH=0 cm、10 cm、20 cm)情况下的迁移转化规律。【结果】结果显示：各取样点土壤水中总砷和As(Ⅴ)浓度的变化幅度与水位波动幅度增减趋势相同，整体表现为柱3(ΔH=20 cm)>柱2(ΔH=10 cm),但土壤水中汞的浓度不受水位波动的影响，整体呈上升趋势。【结论】结果表明：水位的周期性波动主要通过影响波动带介质中关键环境要素特征，进而影响砷在波动带中的迁移转化规律，且水位波动幅度与该影响程度呈正相关，故在进行地下水砷污染风险评价时，不可忽视地下水位波动对砷运移的影响。

Abstract

[Objective] Understanding the migration and transformation patterns of contaminants in the groundwater level fluctuation zone is crucial for uncovering the root causes of groundwater pollution. [Methods] Based on the theory of groundwater solute transport, soil column simulation experiments were conducted to investigate the migration and transformation patterns of arsenic and mercury under different water level fluctuation amplitudes(ΔH=0 cm, 10 cm, 20 cm) in the water level fluctuation zone. [Results] The results showed that the variation amplitude of total arsenic and As(V) concentrations in soil solution at sampling points followed the same trend as the water level fluctuation amplitudes, with an overall performance of column 3(ΔH=20 cm)> column 2(ΔH=10 cm). However, the concentration of mercury in the soil solution was not affected by the water level fluctuation and showed an overall increasing trend. [Conclusion] The result indicate that the periodic fluctuation of the water level mainly affects the characteristics of key environmental factors in the medium of the fluctuation zone, which in turn impacts the migration and transformation patterns of arsenic in this zone. The amplitude of water level fluctuation is positively correlated with the degree of this effect. Therefore, in groundwater arsenic pollution risk assessments, the impact of groundwater level fluctuation on arsenic migration should not be overlooked.

关键词

水位波动 / 波动幅度 / 水环境 / 砷 / 汞 / 迁移转化

Key words

water level fluctuation / fluctuation amplitude / water environment / arsenic / mercury / migration and transformation

基金资助

国家重点研发计划(2018YFC0406403)

山西省青年基金项目(202303021222011)

山西省应用基础研究计划项目(20210302123192)

山西省基础研究计划项目(202303021211048)

山西省基础研究计划项目(201901D111059)