title: Mobility and speciation of arsenic in the coal fly ashes collected from the Savannah River Site (SRS).
abstract: Arsenic (As) leaching from coal fly ash stockpiled at waste disposal sites is a source of environmental concern. An array of techniques including batch extraction and column leaching tests, in combination with speciation analysis of chemically specific As species, was employed to evaluate the mobility of As in fly ashes collected from the U.S. DOE Savannah River Site. The results obtained using the U.S. EPA Toxicity Characteristic Leaching Procedure (TCLP), a two-step sequential extraction technique, and continuous column leaching experiments suggest that only a small portion of total As in the fly ashes was mobile, but mobilizable As could be a considerable fraction (3.1-43%), varying inversely with alkalinity of fly ash. Speciation analysis by using phosphate extraction suggests that arsenate (As(V)) was the major extractable species in the fly ash samples. During the column leaching experiment, however, it was observed that arsenite (As(III)) was an important species leached out of the fly ashes, indicating species conversion during the leaching process. The matrix-bound As(V) within the fly ash, once being released from the solid matrix, could be converted to As(III) during its transport inside the column. The pHs of leachates and fly ashes (both acidic in column leaching experiments here) could be related to the dominance of As(III) in the effluents.
authors.affiliation: Institute of Environment and Health, Jianghan University, Wuhan, 430056, China; Department of Chemistry & Biochemistry, Southeast Environmental Research Center, Florida International University, Miami, FL, 33199, USA. Electronic address: liug@fiu.edu.
authors.forename: Guangliang
authors.initials: G
authors.lastname: Liu
authors.affiliation: Institute of Environment and Health, Jianghan University, Wuhan, 430056, China; Department of Chemistry & Biochemistry, Southeast Environmental Research Center, Florida International University, Miami, FL, 33199, USA.
authors.forename: Yong
authors.initials: Y
authors.lastname: Cai
authors.affiliation: Department of Chemistry & Biochemistry, Southeast Environmental Research Center, Florida International University, Miami, FL, 33199, USA.
authors.forename: Damaris
authors.initials: D
authors.lastname: Hernandez
authors.affiliation: Department of Chemistry & Biochemistry, Southeast Environmental Research Center, Florida International University, Miami, FL, 33199, USA.
authors.forename: Jill
authors.initials: J
authors.lastname: Schrlau
authors.affiliation: Applied Research Center (ARC), Florida International University, Miami, FL, 33174, USA.
authors.forename: Marshall
authors.initials: M
authors.lastname: Allen
mesh_terms: D001149:Arsenates / Q000032:analysis; D001151:Arsenic / Q000032:analysis*; D060729:Coal Ash / Q000032:analysis*; D004784:Environmental Monitoring; D045483:Rivers; D013022:South Carolina; D064091:Waste Disposal Facilities
chemical_list: D001149:Arsenates; D060729:Coal Ash; D001151:Arsenic; C025657:arsenic acid
keywords: Arsenic; Coal fly ash; Mobility; Savannah River Site; Speciation