Soil and Water Science Department, University of Florida, Gainesville, FL 32611, USA.
State Key Laboratory of Pollution Control and Resource Reuse, School of the Environment, Nanjing University, Jiangsu 210046, China; Soil and Water Science Department, University of Florida, Gainesville, FL 32611, USA.
J Hazard Mater. 2014 Jan 15;264:286-92. doi: 10.1016/j.jhazmat.2013.11.009. Epub 2013 Nov 13.
The effects of ionic strength (IS) reduction (5-0.05mM) and flow interruption (FI, flow stopped for 7d) on colloid and Hg release in the leachate were examined in column experiment. Two Hg contaminated soils (13.9 and 146mg/kg) were used, with Hg concentrations in colloids being 2-4 times greater than bulk soils. Based on sequential extraction, Hg concentrations in organic matter (OM) fraction were the most abundant in soils (31-48%). Column leaching after IS reduction and FI released large amounts of colloidal Hg, accounting for 44-48% of released Hg. The highest colloidal Hg concentrations at 27.8 and 360μg/L were observed at ∼1 pore volume after FI. Concentration distribution of colloidal OM and colloidal Fe was similar to colloidal Hg in the leachate, showing peak concentrations after IS reduction and FI. Most of the released colloidal Hg was in OM fraction (37-53%), with some in Fe/Mn oxide fraction (11-19%). Based on composition of released colloids and Hg fractionation in soils and colloids, colloidal OM could serve as an important carrier for Hg transport in soils.
本柱实验研究了离子强度（IS）降低（5-0.05mM）和流动中断（FI，停止流动 7d）对淋出液中胶体和汞释放的影响。使用了两种 Hg 污染土壤（13.9 和 146mg/kg），胶体中的 Hg 浓度是土壤的 2-4 倍。根据顺序提取，土壤中有机质（OM）部分的 Hg 浓度最为丰富（31-48%）。IS 降低和 FI 后柱淋出释放了大量胶体 Hg，占释放 Hg 的 44-48%。FI 后约 1 个孔隙体积时，胶体 Hg 的浓度达到 27.8 和 360μg/L 的最高值。胶体 OM 和胶体 Fe 的浓度分布与淋出液中的胶体 Hg 相似，在 IS 降低和 FI 后达到峰值。释放的大部分胶体 Hg 存在于 OM 部分（37-53%），部分存在于 Fe/Mn 氧化物部分（11-19%）。基于释放胶体的组成和土壤及胶体中 Hg 的分级，胶体 OM 可能是土壤中 Hg 迁移的重要载体。
