Discovering the Mineralogy of Nano-sized Particulate Matter in Smelter Impacted Regions: Transmission Electron Microscopy Studies of Focused Ion Beam Sections Taken from Rock Coatings
Jaime Caplette1, Nathalie Mantha
1, Michael Schindler
1 and Michael F Hochella Jr
2, (1)Laurentian University, Earth Science, Sudbury, ON, Canada, (2)Virginia Tech, Blacksburg, VA, United States
Contact First Author: Jaime Caplette; jn_caplette@laurentian.ca
Previously Published Material: Published Journal Articles:Mantha, N. M., Schindler, M., Murayama, M., and Hochella Jr, M. F. 2012a. Silica- and sulphate-bearing rock coatings in smelter areas: Products of chemical weathering and atmospheric pollution I. Formation and mineralogical composition. Geochimica et Cosmochimica Acta 85: 254-274. Mantha, N. M., Schindler, M., and Kyser, K. T. 2012b. Silica- and sulphate-bearing rock coatings in smelter areas: Part II. Forensic tools for atmospheric metal(loid)- and sulphur-isotope compositions. Geochimica et Cosmochimica Acta 90: 221-241.Schindler, M., Mantha, N.M., Kyser, K.T., Murayama, M., and Hochella Jrsim M.F. 2012. Shining Light on Black Rock Coatings in Smelter-Impacted Areas. Geoscience Canada. 39(3): 148-157.CBC Radio interview, June 2012, Sudbury Ontario. URL: http://www.cbc.ca/news/canada/sudbury/scientist-unlocking-secrets-from-sudbury-s-black-rocks-1.1158083
English Abstract:
This study implements the use of High Resolution Transmission Electron Microscopy (HRTEM) and Focused Ion Beam (FIB) techniques for the investigation of nano-sized particulate matter and secondary mineral phases in black-rock coatings. These coatings occur in the vicinity of the smelter centres in Sudbury, Trail and Rouyn-Noranda, Canada, and are products of past emissions of sulphur dioxide (creating sulphuric acid) and particulate matter. HRTEM studies indicate the presence of emitted particulates and aerosols that became trapped in a viscous amorphous silica gel during coating formation. The identification of these phases gives insight on nano-sized particulate matter that is commonly undetected when examining soils and lake sediments. The HRTEM studies also show that the silica-rich coatings (a) suppress the transformation of secondary phases such as Fe-hydroxides and Fe-sulfates (e.g. jarosite minerals) towards thermodynamically stable phases such as goethite and hematite, and (b) limit the equilibration between pore spaces occupied by nano-sized particulate matter, secondary Fe-Cu-sulfates and jarosite group minerals, and trapped phyllosilicates such as clays and chlorite. The preservation and disequilibria of mineral phases in these silica coatings give insight into past environmental conditions during coating formation and the nature of past and present nano-sized particulate matter emitted by smelters.
