Impact of clay minerals on sulfate-reducing activity in aquifers
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Abstract
Previous studies have shown that sulfate-reduction activity occurs in a heterogeneous manner throughout the terrestrial subsurface. Low-activity regions are often observed in the presence of clay minerals. Here we report that clays inhibit sulfate reduction activity in sediments and in a pure culture of Desulfovibriovulgaris. Clay minerals including bentonite and kaolinite inhibited sulfate reduction by 70–90% in sediments. Intact clays and clay colloids or soluble components, capable of passing through a 0.2-µm filter, were also inhibitory to sulfate-reducing bacteria. Other adsorbent materials, including anion or cation exchangers and a zeolite, did not inhibit sulfate reduction in sediments, suggesting that the effect of clays was not due to their cation-exchange capacity. We observed a strong correlation between the Al2O3content of clays and their relative ability to inhibit sulfate reduction in sediments (r2 = 0.82). This suggested that inhibition might be a direct effect of Al3+ (aq) on the bacteria. We then tested pure aluminum oxide (Al2O3) and showed it to act in a similar manner to clay. As dissolved aluminum is known to be toxic to a variety of organisms at low concentrations, our results suggest that the effects of clay on sulfate-reducing bacteria may be directly due to aluminum. Thus, our experiments provide an explanation for the lack of sulfate-reduction activity in clay-rich regions and presents a mechanism for the effect.
Publication type | Article |
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Publication Subtype | Journal Article |
Title | Impact of clay minerals on sulfate-reducing activity in aquifers |
Series title | Microbial Ecology |
DOI | 10.1007/s00248-003-1021-z |
Volume | 47 |
Issue | 1 |
Year Published | 2004 |
Language | English |
Publisher | Springer-Verlag |
Contributing office(s) | Toxic Substances Hydrology Program |
Description | 7 p. |
First page | 80 |
Last page | 86 |
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