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Time and temperature dependency of carbon dioxide triggered metal(loid) mobilization in soil

Title data

Mehlhorn, Judith ; Byrne, James M. ; Kappler, Andreas ; Planer-Friedrich, Britta:
Time and temperature dependency of carbon dioxide triggered metal(loid) mobilization in soil.
In: Applied Geochemistry. Vol. 74 (November 2016) . - pp. 122-137.
ISSN 0883-2927
DOI: https://doi.org/10.1016/j.apgeochem.2016.09.007

Abstract in another language

Assessing the influence of CO2 on soil and aquifer geochemistry is a task of increasing interest when considering risk assessment for geologic carbon sequestration. Leakage and CO2 ascent can lead to soil acidification and mobilization of potentially toxic metals and metalloids due to desorption or dissolution reactions. We studied the CO2 influence on an Fe(III) (oxyhydr)oxide rich, gleyic Fluvisol sampled in close vicinity to a Czech mofette site and compared the short-term CO2 influence in laboratory experiments with observations on long-term influence at the natural site. Six week batch experiments with/without CO2 gas flow at 3 different temperatures and monitoring of liquid phase metal(loid) concentrations revealed two main short-term mobilization processes. Within 1 h to 1 d after CO2 addition, mobilization of weakly adsorbed metal cations occurred due to surface protonation, most pronounced for Mn (2.5-3.3 fold concentration increase, mobilization rates up to 278±18 µg Mn kgsoil 1 d 1) and strongest at low temperatures. However, total metal(loid) mobilization by abiotic desorption was low. After 1 to 3 d significant Fe mobilization due to microbially-triggered Fe(III) (oxyhydr)oxide dissolution began and continued throughout the experiment (up to 111±24 fold increase or up to 1.9±0.6 mg Fe kgsoil 1 d 1). Rates increased at higher temperature and with a higher content of organic matter. The Fe(III) mineral dissolution was coupled to co-release of incorporated metal(loid)s, shown for As (up to 16±7 fold, 11±8 µg As kgsoil 1 d 1). At high organic matter content, re-immobilization due to resorption reactions could be observed for Cu. The already low pH (4.5-5.0) did not change significantly during Fe(III) reduction due to buffering from sorption and dissolution reactions, but a drop in redox potential (from > +500 mV to minimum +340±20 mV) occurred due to oxygen depletion. We conclude that microbial processes following CO2 induction into a soil can contribute significantly to metal(loid) mobilization, especially at optimal microbial growth conditions (moderate temperature, high organic carbon content) and should be considered for carbon sequestration monitoring and risk assessment.

Further data

Item Type: Article in a journal
Refereed: Yes
Additional notes: BAYCEER137717
Keywords: Mofette; Fluvisol; Carbon Capture and Storage (CCS); Microbial iron reduction; Czech Republic
Institutions of the University: Faculties > Faculty of Biology, Chemistry and Earth Sciences > Department of Earth Sciences > Professorship Environmental Geochemistry Group
Faculties > Faculty of Biology, Chemistry and Earth Sciences > Department of Earth Sciences > Professorship Environmental Geochemistry Group > Professorship Environmental Geochemistry - Univ.-Prof. Dr. Britta Planer-Friedrich
Research Institutions
Research Institutions > Research Centres
Research Institutions > Research Centres > Bayreuth Center of Ecology and Environmental Research- BayCEER
Faculties
Faculties > Faculty of Biology, Chemistry and Earth Sciences
Faculties > Faculty of Biology, Chemistry and Earth Sciences > Department of Earth Sciences
Result of work at the UBT: Yes
DDC Subjects: 500 Science
Date Deposited: 17 Jan 2018 12:26
Last Modified: 17 Jan 2018 12:26
URI: https://eref.uni-bayreuth.de/id/eprint/41376