Biogeochemistry of Aquifer Systems

Cozzarelli, Isabelle M.; Weiss, Johanna V.

doi:10.1128/9781555815882.ch68

Cited by 9 publications

(3 citation statements)

References 137 publications

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“…The existence of different diversity and development of microbial communities that depend on the granulometric and textural characteristics of the media highlights the need to analyze the samples of different granulometries (Albrechtsen, 1994 andHurst et al, 2002). Further down, microbial diversity increases and there is greater variability depending on the predominant lithology and the geochemical characteristics (Cozzarelli and Weiss, 2007). Thus, the microbial diversity is greater and the communities are often more developed where fine granulometry levels predominate (silt and clay, as in the case of samples M4 and M5).…”

Section: Microbial Heterogeneitymentioning

confidence: 99%

Subsoil heterogeneities controlling porewater contaminant mass and microbial diversity at a site with a complex pollution history

Puigserver

Carmona

Cortés

et al. 2013

Journal of Contaminant Hydrology

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Section: Microbial Heterogeneitymentioning

confidence: 99%

Subsoil heterogeneities controlling porewater contaminant mass and microbial diversity at a site with a complex pollution history

Puigserver

Carmona

Cortés

et al. 2013

Journal of Contaminant Hydrology

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“…Aquifers are commonly segmented into geochemical zones within which the activity of a single functional group, such as the sulfate reducers or iron reducers, is thought to predominate [ Chapelle , 2001; Cozzarelli and Weiss , 2007]. Many researchers have attributed this apparent segregation to competitive exclusion.…”

Section: Introductionmentioning

confidence: 99%

The active bacterial community in a pristine confined aquifer

Flynn

Sanford

Domingo

et al. 2012

Water Resources Research

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[1] This study of the active bacteria residing in a pristine confined aquifer provides unexpected insights into the ecology of iron-reducing and sulfate-reducing bacteria in the subsurface. At 18 wells, we trapped the microbes that attached to aquifer sediment and used molecular techniques to examine the bacterial populations. We used multivariate statistics to compare the composition of bacterial communities among the wells with respect to the chemistry of the groundwater. We found groundwater at each well was considerably richer in ferrous iron than sulfide, indicating iron-reducing bacteria should, by established criteria, dominate the sulfate reducers. Our results show, however, that areas where groundwater contains more than a negligible amount of sulfate (>0.03 mM), populations related to sulfate reducers of the genera Desulfobacter and Desulfobulbus were of nearly equal abundance with putative iron reducers related to Geobacter, Geothrix, and Desulfuromonas. Whereas sulfate is a key discriminant of bacterial community structure, we observed no statistical relationship between the distribution of bacterial populations in this aquifer and the concentration of either ferrous iron or dissolved sulfide. These results call into question the validity of using the relative concentration of these two ions to predict the nature of bacterial activity in an aquifer. Sulfate reducers and iron reducers do not appear to be segregated into discrete zones in the aquifer, as would be predicted by the theory of competitive exclusion. Instead, we find the two groups coexist in the subsurface in what we suggest is a mutualistic relationship.

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“…Previous research on soils experiencing fluctuating redox conditions and active iron cycling have shown they frequently lack ‘typical’ Fe(III)-respiring bacteria (65), being outcompeted by sulfate respiration (66). Despite Fe(III) being a more thermodynamically favourable electron acceptor it is commonly acknowledged that sulfate respiration often outcompetes Fe(III) respiration in both high and low sulfate environments (66, 67). High levels of sulfate reduction in low-sulfate environments, akin to the LFLS trenches, has been previously observed to occur in the presence of crystalline Fe(III) oxyhydroxides that partially re-oxidise sulfide generated by SRB to elemental sulfur (67).…”

Section: Resultsmentioning

confidence: 99%

Response of microbial community function to fluctuating geochemical conditions within a legacy radioactive waste trench environment

Vázquez-Campos

Kinsela

Bligh

et al. 2017

Preprint

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During the 1960s, small quantities of radioactive materials were co-disposed with chemical waste at the Little Forest Legacy Site (Sydney, Australia) in three-metre-deep, unlined trenches. Chemical and microbial analyses, including functional and taxonomic information derived from shotgun metagenomics, were collected across a six-week period immediately after a prolonged rainfall event to assess how changing water levels impact upon the microbial ecology and contaminant mobility. Collectively, results demonstrated that oxygen-laden rainwater rapidly altered the redox balance in the trench water, strongly impacting microbial functioning as well as the radiochemistry. Two contaminants of concern, plutonium and americium, were shown to transition from solid-iron-associated species immediately after the initial rainwater pulse, to progressively more soluble moieties as reducing conditions were enhanced. Functional metagenomics revealed the potentially important role that the taxonomically-diverse microbial community played in this transition. In particular, aerobes dominated in the first day followed by an increase of facultative anaerobes/denitrifiers at day four. Towards the mid-end of the sampling period, the functional and taxonomic profiles depicted an anaerobic community distinguished by a higher representation of dissimilatory sulfate reduction and methanogenesis pathways. Our results have important implications to similar near-surface environmental systems in which redox cycling occurs.ImportanceThe role of chemical and microbiological factors in mediating the biogeochemistry of groundwaters from trenches used to dispose of radioactive materials during the 1960s is examined in this study. Specifically, chemical and microbial analyses, including functional and taxonomic information derived from shotgun metagenomics, were collected across a six-week period immediately after a prolonged rainfall event to assess how changing water levels influence microbial ecology and contaminant mobility.Results demonstrate that oxygen-laden rainwater rapidly altered the redox balance in the trench water, strongly impacting microbial functioning as well as the radiochemistry. Two contaminants of concern, plutonium and americium, were shown to transition from solidiron-associated species immediately after the initial rainwater pulse, to progressively more soluble moieties as reducing conditions were enhanced. Functional metagenomics revealed the important role that the taxonomically-diverse microbial community played in this transition. Our results have important implications to similar near-surface environmental systems in which redox cycling occurs.

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Biogeochemistry of Aquifer Systems

Cited by 9 publications

References 137 publications

Subsoil heterogeneities controlling porewater contaminant mass and microbial diversity at a site with a complex pollution history

Subsoil heterogeneities controlling porewater contaminant mass and microbial diversity at a site with a complex pollution history

The active bacterial community in a pristine confined aquifer

Response of microbial community function to fluctuating geochemical conditions within a legacy radioactive waste trench environment

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