Broad-scale evidence that pH influences the balance between microbial iron and sulfate reduction

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dc.contributor.author Kirk, Matthew F. en_US
dc.contributor.author Jin, Qusheng en_US
dc.contributor.author Haller, Ben R. en_US
dc.date.accessioned 2016-01-25T16:37:03Z
dc.date.available 2016-01-25T16:37:03Z
dc.identifier.uri http://hdl.handle.net/2097/27646
dc.description Understanding basic controls on aquifer microbiology is essential to managing water resources and predicting impacts of future environmental change. Previous theoretical and laboratory studies indicate that pH can influence interactions between microorganisms that reduce ferric iron and sulfate. In this study, we test the environmental relevance of this relationship by examining broad-scale geochemical data from anoxic zones of aquifers. We isolated data from the U.S. Geological Survey National Water Information System for 19 principal aquifer systems. We then removed samples with chemical compositions inconsistent with iron- and sulfate-reducing environments and evaluated the relationships between pH and other geochemical parameters using Spearman's rho rank correlation tests. Overall, iron concentration and the iron-sulfide concentration ratio of groundwater share a statistically significant negative correlation with pH (P < 0.0001). These relationships indicate that the significance of iron reduction relative to sulfate reduction tends to increase with decreasing pH. Moreover, thermodynamic calculations show that, as the pH of groundwater decreases, iron reduction becomes increasingly favorable relative to sulfate reduction. Hence, the relative significance of each microbial reaction may vary in response to thermodynamic controls on microbial activity. Our findings demonstrate that trends in groundwater geochemistry across different regional aquifer systems are consistent with pH as a control on interactions between microbial iron and sulfate reduction. Environmental changes that perturb groundwater pH can affect water quality by altering the balance between these microbial reactions. en_US
dc.description Citation: Kirk, M. F., Jin, Q. and Haller, B. R. (2015), Broad-Scale Evidence That pH Influences the Balance Between Microbial Iron and Sulfate Reduction. Groundwater. doi:10.1111/gwat.12364 en_US
dc.relation.uri http://dx.doi.org/10.1111/gwat.12364 en_US
dc.rights This is a post-print version of an article published by Wiley in the journal Groundwater on 18/08/2015, available online: http://dx.doi.org/10.1111/gwat.12364. en_US
dc.rights.uri http://www.sherpa.ac.uk/romeo/issn/0017-467X/ en_US
dc.subject microbiology en_US
dc.subject water quality en_US
dc.subject groundwater en_US
dc.subject geochemistry en_US
dc.subject bioenergetics en_US
dc.subject principal aquifer system en_US
dc.title Broad-scale evidence that pH influences the balance between microbial iron and sulfate reduction en_US
dc.type Text en_US
dc.date.published 2015 en_US
dc.citation.doi 10.1111/gwat.12364 en_US
dc.citation.issn 0017-467X en_US
dc.citation.jtitle Groundwater en_US
dc.contributor.authoreid mfkirk en_US


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