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Effect of cyanide-mineral interactions on granite weathering in a glacier forefield

Applicant Furrer Gerhard
Number 140857
Funding scheme Interdisciplinary projects
Research institution Institut für Biogeochemie und Schadstoffdynamik ETH Zürich
Institution of higher education ETH Zurich - ETHZ
Main discipline Pedology
Start/End 01.05.2012 - 30.04.2013
Approved amount 54'109.00
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All Disciplines (2)

Discipline
Pedology
Environmental Research

Keywords (7)

Cyanogenic microorganisms; Granite; Nutrients; Organic ligands; Alpine glacier forefield; Initial soil formation; Mineral weathering

Lay Summary (English)

Lead
Lay summary

This is a follow-on of a running SNF project (NSF K-23K1-120601) with the same title. As the previous project it addresses the most important gaps in the knowledge of biogeochemical weathering in alpine areas. Weathering is seen as provision of nutrients that are required by the pioneering life in deglaciated alpine areas, where soil development is at its initial stage. In the course of glacier retrieval and loss of permafrost, rocks become loose and subject to erosion. This development can be limited or prevented only if soil and vegetation cover is developed rapidly. Where terrestrial life has to evolve under harsh conditions, microbial colonization is slow. This is related to the fact that dissolution of most primary rock-forming minerals is limited by slow reaction kinetics. The project is focused on the mineral-water interface, where aqueous solutes act directly as dissolution-promoting agents. The rates are dependent on intrinsic (e.g. mineral-surface properties, weathering state) and extrinsic factors (e.g. temperature, pH, redox conditions, presence of biotic exudates). Fine rock materials, that are most important for nutrient supply can have either freshly exposed or weathered surfaces. Both kind of rock material are studied systematically with respect to proton- and ligand-promoted dissolution, considering cyanide as well as the organic ligands oxalate and citrate (although salicylate has been suggested in the original proposal). In addition to freshly ground granite from the Damma glacier area, we sampled and investigated sediments from differently exposed sites. The fine rock material was exposed to the field conditions in parallel to reference material of mica (in part biotite, K and Fe source), and apatite (accessory mineral, P source).

The main objectives of the running project include the study of (1) intrinsic and (2) extrinsic weathering factors, (3) ligand-promoted dissolution, (4) the weathering potential of cyanide-producing bacteria, and (5) computer modelling of weathering processes in the glacier forefield. In deviation of the original proposal, the extrinsic factor temperature was not investigated, as well as the comparison of flow-through vs. batch experiments. This decision was taken after intense work on the experimental setup, where we experienced serious difficulties to control the partial pressure of the hydrogen cyanide gas in the reactor. Consequently we decided to stick to batch experiments and to use sodium cyanide salt in combination with pH adjustment. The main body of the other tasks are planned to be fulfilled in the course of the remaining project time including the extension period.

Direct link to Lay Summary Last update: 21.02.2013

Responsible applicant and co-applicants

Employees

Name Institute

Collaboration

Group / person Country
Types of collaboration
Prof. Jens Götze, TU Bergakademie Freiberg Germany (Europe)
- in-depth/constructive exchanges on approaches, methods or results
- Publication
- Research Infrastructure

Scientific events

Active participation

Title Type of contribution Title of article or contribution Date Place Persons involved
Eurosoil 2012 02.06.2012 Bari, Italy


Associated projects

Number Title Start Funding scheme
120601 Effect of cyanide-mineral interactions on granite weathering in a glacier forefield 01.05.2009 Interdisciplinary projects
137715 Quantification of environmental effects on the weathering state of rock surfaces 01.11.2011 Project funding (Div. I-III)

Abstract

This is an application for a follow-on of a running SNF project (NSF K-23K1-120601) with the same title. The extension of 12 months is required mainly to accomplish some important parts that will not be finished by the end of the main project’s third year. Most topics listed in the time schedule of the running project were or will be covered by May 2012. However, some additional experiments on the central aspect of phosphate mobilization, the evaluation and interpretation of data, computer modelling, and writing publications will take more time. All costs for equipment, consumables, traveling are covered by the running SNF project and our own funding. We only apply for personal costs of the PhD student during the 12 months of extension.The project addresses some of the most important gaps in the knowledge of biogeochemical weathering in alpine areas. Weathering is seen as provision of nutrients that are required by the pioneering life in deglaciated alpine areas, where soil development is at its initial stage. In the course of glacier retrieval and loss of permafrost, rocks become loose and subject to erosion. This development can be limited or prevented only if soil and vegetation cover is developed rapidly. Where terrestrial life has to evolve under harsh conditions, microbial colonization is slow. This is related to the fact that dissolution of most primary rock-forming minerals is limited by slow reaction kinetics. The project is focused on the mineral-water interface, where aqueous solutes act directly as dissolution-promoting agents.The rates are dependent on intrinsic (e.g. mineral-surface properties, weathering state) and extrinsic factors (e.g. temperature, pH, redox conditions, presence of biotic exudates). Fine rock materials, that are most important for nutrient supply can have either freshly exposed or weathered surfaces. Both kind of rock material are studied systematically with respect to proton- and ligand-promoted dissolution, considering cyanide as well as the organic ligands oxalate and citrate (although salicylate has been suggested in the original proposal). In addition to freshly ground granite from the Damma glacier area, we sampled and investigated sediments from differently exposed sites. The fine rock material was exposed to the field conditions in parallel to reference material of mica (in part biotite, K and Fe source), and apatite (accessory mineral, P source).The main objectives of the running project include the study of (1) intrinsic and (2) extrinsic weathering factors, (3) ligand-promoted dissolution, (4) the weathering potential of cyanide-producing bacteria, and (5) computer modelling of weathering processes in the glacier forefield. In deviation of the original proposal, the extrinsic factor temperature was not investigated, as well as the comparison of flow-through vs. batch experiments. This decision was taken after intense work on the experimental setup, where we experienced serious difficulties to control the partial pressure of the hydrogen cyanide gas in the reactor. Consequently we decided to stick to batch experiments and to use sodium cyanide salt in combination with pH adjustment. The main body of the other tasks are planned to be fulfilled in the course of the remaining project time including the extension period.
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