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

Titelangaben

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. Bd. 74 (November 2016) . - S. 122-137.
ISSN 0883-2927
DOI: https://doi.org/10.1016/j.apgeochem.2016.09.007

Abstract

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.

Weitere Angaben

Publikationsform: Artikel in einer Zeitschrift
Begutachteter Beitrag: Ja
Zusätzliche Informationen: BAYCEER137717
Keywords: Mofette; Fluvisol; Carbon Capture and Storage (CCS); Microbial iron reduction; Czech Republic
Institutionen der Universität: Fakultäten > Fakultät für Biologie, Chemie und Geowissenschaften > Fachgruppe Geowissenschaften > Professur Umweltgeochemie
Fakultäten > Fakultät für Biologie, Chemie und Geowissenschaften > Fachgruppe Geowissenschaften > Professur Umweltgeochemie > Professur Umweltgeochemie - Univ.-Prof. Dr. Britta Planer-Friedrich
Forschungseinrichtungen
Forschungseinrichtungen > Forschungszentren
Forschungseinrichtungen > Forschungszentren > Bayreuther Zentrum für Ökologie und Umweltforschung - BayCEER
Fakultäten
Fakultäten > Fakultät für Biologie, Chemie und Geowissenschaften
Fakultäten > Fakultät für Biologie, Chemie und Geowissenschaften > Fachgruppe Geowissenschaften
Titel an der UBT entstanden: Ja
Themengebiete aus DDC: 500 Naturwissenschaften und Mathematik
Eingestellt am: 17 Jan 2018 12:26
Letzte Änderung: 17 Jan 2018 12:26
URI: https://eref.uni-bayreuth.de/id/eprint/41376