Document Detail

Microbial diversity and impact on carbonate geochemistry across a changing geochemical gradient in a karst aquifer.
MedLine Citation:
PMID:  23151637     Owner:  NLM     Status:  MEDLINE    
Although microbes are known to influence karst (carbonate) aquifer ecosystem-level processes, comparatively little information is available regarding the diversity of microbial activities that could influence water quality and geological modification. To assess microbial diversity in the context of aquifer geochemistry, we coupled 16S rRNA Sanger sequencing and 454 tag pyrosequencing to in situ microcosm experiments from wells that cross the transition from fresh to saline and sulfidic water in the Edwards Aquifer of central Texas, one of the largest karst aquifers in the United States. The distribution of microbial groups across the transition zone correlated with dissolved oxygen and sulfide concentration, and significant variations in community composition were explained by local carbonate geochemistry, specifically calcium concentration and alkalinity. The waters were supersaturated with respect to prevalent aquifer minerals, calcite and dolomite, but in situ microcosm experiments containing these minerals revealed significant mass loss from dissolution when colonized by microbes. Despite differences in cell density on the experimental surfaces, carbonate loss was greater from freshwater wells than saline, sulfidic wells. However, as cell density increased, which was correlated to and controlled by local geochemistry, dissolution rates decreased. Surface colonization by metabolically active cells promotes dissolution by creating local disequilibria between bulk aquifer fluids and mineral surfaces, but this also controls rates of karst aquifer modification. These results expand our understanding of microbial diversity in karst aquifers and emphasize the importance of evaluating active microbial processes that could affect carbonate weathering in the subsurface.
Cassie J Gray; Annette S Engel
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Publication Detail:
Type:  Journal Article; Research Support, Non-U.S. Gov't     Date:  2012-11-15
Journal Detail:
Title:  The ISME journal     Volume:  7     ISSN:  1751-7370     ISO Abbreviation:  ISME J     Publication Date:  2013 Feb 
Date Detail:
Created Date:  2013-01-22     Completed Date:  2013-11-14     Revised Date:  2014-02-04    
Medline Journal Info:
Nlm Unique ID:  101301086     Medline TA:  ISME J     Country:  England    
Other Details:
Languages:  eng     Pagination:  325-37     Citation Subset:  IM    
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MeSH Terms
Calcium Carbonate / chemistry
Fresh Water / chemistry,  microbiology
Groundwater / chemistry*,  microbiology*
Magnesium / chemistry
Minerals / chemistry
Models, Chemical
Proteobacteria / classification,  isolation & purification*
RNA, Ribosomal, 16S / analysis
Water Microbiology*
Reg. No./Substance:
0/Minerals; 0/RNA, Ribosomal, 16S; 16389-88-1/dolomite; H0G9379FGK/Calcium Carbonate; I38ZP9992A/Magnesium

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine

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