HR: 0830h
AN: B21C-0734    [PDF]
TI: Transport of Colloid-Associated Arsenic and Mercury: Column Experiments and Microscopic, Spectroscopic, and Chemical Analyses of Colloidal Material
AU: * Slowey, A J
EM: aslowey@pangea.stanford.edu
AF: Department of Geological and Environmental Sciences, Room 118, Building 320, Stanford, CA 94305-2115 United States
AU: Johnson, S B
EM: stevebj@pangea.stanford.edu
AF: Department of Geological and Environmental Sciences, Room 118, Building 320, Stanford, CA 94305-2115 United States
AU: Rytuba, J J
EM: jrytuba@usgs.gov
AF: U.S. Geological Survey, Geologic Division, 345 Middlefield Rd, MS 901, Menlo Park, CA 94025 United States
AU: Brown, G E
EM: gordon@pangea.stanford.edu
AF: Department of Geological and Environmental Sciences, Room 118, Building 320, Stanford, CA 94305-2115 United States
AB: Heavy metal contaminants in aqueous solutions can be transported as dissolved or particle-associated species. While transport of dissolved species has received more attention, under certain conditions, transport of heavy metals associated with colloidal particles is also significant. Important issues to address are (1) the physicochemical conditions under which colloidal particles are mobilized, (2) the nature of the colloidal particles and the way(s) in which heavy metals are associated with them, and (3) the extent of particle-associated heavy metal transport. In this study, bench-scale column experiments were performed to demonstrate particle-based transport of arsenic and mercury from a calcined ore obtained from the inoperative Sulphur Bank mercury mine in the Northern California coast range. The calcines were exposed to organic acids and electrolyte as a means of simulating environmental perturbations that commonly cause mobilization of colloids in similar matrices. The arsenic and mercury species associated with the mobilized particles were characterized using Hg L(III)- and As K-edge x-ray absorption fine structure (XAFS) spectroscopy, scanning electron microscopy with energy dispersive spectroscopy (SEM-EDS), and analytical transmission electron microscopy (ATEM). Most of the mobilized arsenic and mercury was in particulate forms, comprising As(V)-Fe(oxy)hydroxide surface complexes or coprecipitates, As(V)-substituted jarosite (KFe$_{3}$(SO$_{4}$,AsO$_{4}$)$_{2}$(OH)$_{6}$), HgS (cinnabar and metacinnabar), and corderoite (Hg$_{3}$S$_{2}$Cl$_{2}$).
UR: http://pangea.stanford.edu/research/saag/aaron.htm
DE: 1806 Chemistry of fresh water
DE: 1871 Surface water quality
DE: 3670 Minor and trace element composition
DE: 3954 X ray, neutron, and electron spectroscopy and diffraction
DE: 4809 Colloids
SC: Biogeosciences [B]
MN: 2003 Fall Meeting