Lithological controls on biological activity and groundwater chemistry in Quaternary sediments
Article first published online: 24 NOV 2009
Copyright © 2009 John Wiley & Sons, Ltd.
Volume 24, Issue 6, pages 726–735, 15 March 2010
How to Cite
Bartlett, R., Bottrell, S. H., Sinclair, K., Thornton, S., Fielding, I. D. and Hatfield, D. (2010), Lithological controls on biological activity and groundwater chemistry in Quaternary sediments. Hydrol. Process., 24: 726–735. doi: 10.1002/hyp.7514
- Issue published online: 24 FEB 2010
- Article first published online: 24 NOV 2009
- Manuscript Accepted: 24 SEP 2009
- Manuscript Received: 7 OCT 2008
- Natural Environmental Research Council (NERC). Grant Numbers: GR3/8134, GR9/3492
- bacterial sulfate reduction;
- grain size;
- size exclusion;
- biological activity
Depth profiles of solute chemistry and sulfate isotopic compositions are presented for groundwater and pore water in a sequence of Quaternary glacial outwash sediments. Sand units show evidence for hydraulic connection to the surface and thus modern sources of solutes. Finer-grained sediments show a general pattern of increasing solute concentrations with depth, with sulfate derived from ancient rainwater and pyrite oxidation in the soil/drift. In these sediments sulfate has undergone bacterial sulfate reduction (BSR) to produce biogenic sulfide. In clay sediments, with d10 ≤ 1·6 µm, high concentrations of sulfate and acetate now co-exist, implying that BSR is inhibited. The correlation with smaller sediment grain size indicates that this is due to pore size exclusion of the sulfate reducing bacteria. Mechanical restriction of microbial function thus provides a fundamental limitation on microbial respiration in buried clay-rich sediments, which acts as a control on the chemical evolution of their pore waters. Copyright © 2009 John Wiley & Sons, Ltd.