dc.citation.doi	10.1111/gwat.12364	en_US
dc.citation.issn	0017-467X	en_US
dc.citation.jtitle	Groundwater	en_US
dc.contributor.author	Kirk, Matthew F.	en_US
dc.contributor.author	Jin, Qusheng	en_US
dc.contributor.author	Haller, Ben R.	en_US
dc.contributor.authoreid	mfkirk	en_US
dc.date.accessioned	2016-01-25T16:37:03Z
dc.date.available	2016-01-25T16:37:03Z
dc.date.published	2015	en_US
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.identifier.uri	http://hdl.handle.net/2097/27646
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

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

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