GEOC 47 |
| Aaron J. Slowey1, Stephen B. Johnson1, James J. Rytuba2, and Gordon E. Brown Jr.1. (1) Geological & Environmental Sciences, Stanford University, Room 118, Building 320, Stanford, CA 94305-2115, (2) Mineral Resources Program, United States Geological Survey, 345 Middlefield Rd, MS 901, Menlo Park, CA 94025 |
| Inoperative mercury mines contaminate surrounding ecosystems via transport of dissolved and particle-associated species of mercury and other heavy metal(loid)s. By leaching columns of a calcined mercury ore with organic acid solutions, simulating infiltration through the rooting zone of revegetated mine waste, this study addresses (1) the physicochemical conditions under which colloids are mobilized, (2) the speciation of mercury and arsenic in mobilized colloids, and (3) the extent of colloidal mercury and arsenic transport. Mercury and arsenic speciation was performed using Hg L- and As K-edge X-ray absorption fine structure (XAFS) spectroscopy, SEM-EDS, and TEM. Chemical analysis of eluted colloids and 0.02-mm filtrates of column effluent indicates that 98% of mercury and all arsenic mobilized from the column were in particulate forms. HgS minerals (cinnabar and metacinnabar) constitute the majority of mercury species in the mobilized colloids. Arsenic species comprise both As(V)-Fe(oxy)hydroxide surface complexes and detrital and authigenic minerals. |
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Colloid-Facilitated Transport of Contaminants in the Subsurface: The Life and Death of a Colloid
1:00 PM-5:20 PM, Monday, March 29, 2004 Marriott -- Marquis NW, Oral
Division of Geochemistry |