title: Ionic strength reduction and flow interruption enhanced colloid-facilitated Hg transport in contaminated soils.
abstract: 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.
authors: Soil and Water Science Department, University of Florida, Gainesville, FL 32611, USA.
authors: Yingjia
authors: Y
authors: Zhu
authors: 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. Electronic address: lqma@ufl.edu.
authors: Lena Q
authors: LQ
authors: Ma
authors: Soil and Water Science Department, University of Florida, Gainesville, FL 32611, USA.
authors: Xiaoling
authors: X
authors: Dong
authors: Soil and Water Science Department, University of Florida, Gainesville, FL 32611, USA.
authors: Willie G
authors: WG
authors: Harris
authors: Department of Environmental Engineering and Sciences, University of Florida, Gainesville, FL 32611, USA.
authors: J C
authors: JC
authors: Bonzongo
authors: Department of Chemistry and Biochemistry, Jackson State University, MS 39217, USA.
authors: Fengxiang
authors: F
authors: Han
mesh_terms: D003102:Colloids; D008628:Mercury / Q000737:chemistry*; D009994:Osmolar Concentration; D012989:Soil Pollutants / Q000737:chemistry*
chemical_list: D003102:Colloids; D012989:Soil Pollutants; D008628:Mercury
keywords: Colloidal Hg; Flow interruption; Ionic strength reduction; Iron oxide; Organic matter