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Cyanide-promoted mineral weathering in a glacier forefield

Abstract:

Granite rock materials were sampled from the most recent postglacial zone of the Damma glacier, Switzerland, to study the processes at the mineral-water interface where aqueous solutes act directly as dissolution-promoting agents. An interdisciplinary research project was initiated to gain insights on rock weathering through a linkage of mineralogy, chemistry and microbiology with special emphasis on cyanide as ligand and complexing agent. In previous work, Gärtner et al. [1] found the effects of cyanide on granite dissolution using batch reactors at pH 5.5 and pH 6. The presence of cyanide leads to increased dissolution of phosphate and essential trace elements (silica, magnesium, calcium) and precipitation of iron and manganese. Many Pseudomonas species that are able to produce cyanide have been found in soil sampled from the Damma glacier forefield [2]. Hummel [3] suggested that the formation of iron cyanides is an important and strongly pH-depending factor influencing indirectly the concentration of dissolved of phosphate. Therefore, cyanide-producing bacteria might make use of several advantages where cyanide can act as dissolution-promoting ligand in order to mobilize nutrients and trace elements and help to control competitors. This study aims at the chemistry of cyanide and the microbiologal aspects resulting in dissolution of minerals and soil formation. A systematic investigation including modeling will be carrried out under various conditions to study intrinsic effects (dissolution kinetics) and extrinsic effects (pH, Temperature, concentration of cyanide) on the cyanidepromoted dissolution. The weathering potential of biogenic cyanide will be assessed with respect to cyanide-producing microorganisms isolated from glacier forefield soils. [1] Gärtner (2007). Diploma Thesis, Dept. of Env. Engin. Sci., ETH Zurich, Switzerland. [2] Edwards et al. (2006) Microbial Ecology 52, 679-692. [3] Hummel (2004) Environmental Geology 45, 633-646.

Authors:

Wongfun, Nuttakan and Furrer, Gerhard and Plötze, Michael and Brandl, Helmut

Index Terms:

glacier; cyanide; granite; ClayGroup; Damma; weathering; BigLink; Brandl, Helmut; Furrer, Gerhard; Plotze, Michael; Wongfun, Nuttakan

Further Information:

Date published: 2009