Leachability of potentially toxic elements from soils:New insights into coupled effects of acidification and freeze-thaw
Little was known about the leaching behavior of potentially toxic elements(PTEs)from soils under the interaction between freeze-thaw(F-T)cycle and the solutions of varying pH values.In this study,PTEs leachability from soils before and after F-T tests was evaluated using toxicity characteristics leaching procedure(TCLP)test.The microstructure and mineralogical evolution of soil mineral particles were conducted using pores(particles)and cracks analysis system(PCAS)and PHREEQC.The results indicated that during 30 F-T cycles,the maximum leaching concentrations of PTEs were 0.22 mg/L for As,0.61 mg/L for Cd,2.46 mg/L for Cu,3.08 mg/L for Mn,29.36 mg/L for Pb and 8.07 mg/L for Zn,respectively.Under the coupled effects of F-T cycle and acidification,the porosity of soil particles increased by 4.79%,as confirmed by the microstructure damage caused by the evolution of pores and cracks.The anisotropy of soil particles increased under F-T effects,whereas that decreased under the coupled effects of F-T cycle and acidification.The results from SEM-EDS,PCAS quantification and PHREEQC modeling indicated that the release mechanism of PTEs was not only associated with the microstructure change in mineral particles,but also affected by protonation,as well as the dissolution and precipitation of minerals.Overall,these results would provide an important reference for soil remediation assessments in seasonal frozen areas.
contaminated soilspotentially toxic elements leachabilityfreeze-thaw cyclesacidificationpores(particles)and cracks analysis systemPHREEQC software
付田雨、李捷、付融冰
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State Key Laboratory of Pollution Control and Resources Reuse,College of Environmental Science and Engineering,Tongji University,Shanghai 200092,China
Institute of Environmental and Municipal Engineering,Qingdao University of Technology,Qingdao 266033,China
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