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Soil memory in mineral surface coatings; environmental processes recorded at the nanoscale

Michael Schindler and Michael F. Hochella
Soil memory in mineral surface coatings; environmental processes recorded at the nanoscale
Geology (Boulder) (March 2015) 43 (5): 415-418

Abstract

This study shows that mineral surface coatings in upper soil horizons can preserve products of past abiotic and biotic soil processes and are thus able to record environmental changes on the nanoscale. Contrary to studies involving paleosols, the soil memory of coatings can only be deciphered with high-resolution transmission electron microscopy (HRTEM) on samples prepared using focused ion beam technology. To demonstrate this method, mineral grains were collected in the shallow soils of the Greater Sudbury area, Ontario, Canada, where large fluctuations in the soil pH have occurred during emissions of vast amounts of sulfuric acid and particulate matter (a result of decades of smelter activity in the Sudbury mining district) and subsequent reclamation efforts using lime and phosphates. Observations with HRTEM indicate that limited diffusion of elements in silicified Fe-hydroxide coatings has been the key to the preservation of a rarely observed mineralogy and chemistry. The most intriguing features include petrified cocci in proximity to a structural analogue of green rust (formed prior to the peak of smelter emissions), pockets of jarosite encapsulated by amorphous silica (peak of the smelter emissions), chains of biogenic magnetite, and Fe-(hydr)oxides with high amounts of adsorbed phosphate species (during and after reclamation). These observations indicate that chemical processes in confined pore and interface spaces are commonly in disequilibrium with the surrounding soil, and that Fe-silica-bearing coatings can be excellent tracking tools for the evolution of the chemistry of soils and sediments.


ISSN: 0091-7613
EISSN: 1943-2682
Coden: GLGYBA
Serial Title: Geology (Boulder)
Serial Volume: 43
Serial Issue: 5
Title: Soil memory in mineral surface coatings; environmental processes recorded at the nanoscale
Affiliation: Laurentian University, Department of Earth Sciences, Sudbury, ON, Canada
Pages: 415-418
Published: 20150327
Text Language: English
Publisher: Geological Society of America (GSA), Boulder, CO, United States
References: 36
Accession Number: 2015-039982
Categories: Soils
Document Type: Serial
Bibliographic Level: Analytic
Annotation: GSA Data Repository item 2015146
Illustration Description: illus.
N46°15'00" - N47°00'00", W81°34'60" - W80°34'60"
Secondary Affiliation: Virginia Polytechnic Institute and State University, USA, United States
Country of Publication: United States
Secondary Affiliation: GeoRef, Copyright 2017, American Geosciences Institute. Reference includes data from GeoScienceWorld, Alexandria, VA, United States. Reference includes data supplied by the Geological Society of America, Boulder, CO, United States
Update Code: 201519
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