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Influences of pH and substrate supply on the ratio of iron to sulfate reduction
- Source :
- Geobiology. 19:405-420
- Publication Year :
- 2021
- Publisher :
- Wiley, 2021.
-
Abstract
- Iron reduction and sulfate reduction often occur simultaneously in anoxic systems, and where that is the case, the molar ratio between the reactions (i.e., Fe/SO42- reduced) influences their impact on water quality and carbon storage. Previous research has shown that pH and the supply of electron donors and acceptors affect that ratio, but it is unclear how their influences compare and affect one another. This study examines impacts of pH and the supply of acetate, sulfate, and goethite on the ratio of iron to sulfate reduction in semi-continuous sediment bioreactors. We examined which parameter had the greatest impact on that ratio and whether the parameter influences depended on the state of each other. Results show that pH had a greater influence than acetate supply on the ratio of iron to sulfate reduction, and that the impact of acetate supply on the ratio depended on pH. In acidic reactors (pH 6.0 media), the ratio of iron to sulfate reduction decreased from 3:1 to 2:1 as acetate supply increased (0-1 mM). In alkaline reactors (pH 7.5 media), iron and sulfate were reduced in equal proportions, regardless of acetate supply. Secondly, a comparison of experiments with and without sulfate shows that the extent of iron reduction was greater if sulfate reduction was occurring and that the effect was larger in alkaline reactors than acidic reactors. Thus, the influence of sulfate supply on iron reduction extent also depended on pH and suggests that iron reduction grows more dependent on sulfate reduction as pH increases. Our results compare well to trends in groundwater geochemistry and provide further evidence that pH is a major control on iron and sulfate reduction in systems with crystalline (oxyhydr)oxides. pH not only affects the ratio between the reactions but also the influences of other parameters on that ratio.
- Subjects :
- Goethite
010504 meteorology & atmospheric sciences
Iron
Inorganic chemistry
iron reduction
anoxic environments
010502 geochemistry & geophysics
01 natural sciences
chemistry.chemical_compound
sulfate reduction
Bioreactor
goethite
Sulfate
Groundwater
Ecology, Evolution, Behavior and Systematics
0105 earth and related environmental sciences
General Environmental Science
biology
Sulfates
Substrate (chemistry)
Hydrogen-Ion Concentration
biology.organism_classification
Anoxic waters
Iron reduction
chemistry
visual_art
visual_art.visual_art_medium
General Earth and Planetary Sciences
Water quality
Geobacter
Oxidation-Reduction
Subjects
Details
- ISSN :
- 14724669 and 14724677
- Volume :
- 19
- Database :
- OpenAIRE
- Journal :
- Geobiology
- Accession number :
- edsair.doi.dedup.....993880461f33d946513124500204702c