Halogen geochemistry of the McMurdo dry valleys lakes, Antarctica: Clues to the origin of solutes and lake evolution

Lyons, W. Berry; Welch, Kathleen A.; Snyder, G. T.; Olesik, John W.; Graham, Elizabeth; Marion, G. M.; Poreda, Robert J.

doi:10.1016/j.gca.2004.06.040

Cited by 72 publications

(89 citation statements)

References 86 publications

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“…Hypersaline, iron-rich, liquid brine episodically drains from Taylor Glacier at Blood Falls, which is the end of a conduit where this subglacial brine emerges to meet the atmosphere. The ionic compositions and 36 Cl values for outflow at Blood Falls are consistent with those for marine waters that have experienced cryogenic concentration (41,43). The subglacial brine is thought to be a remnant of seawater originating from the last marine incursion into the McMurdo Dry Valley network during the Pliocene Epoch (ϳ5 million years ago), when the Dry Valleys were fjord lands (17).…”

supporting

confidence: 64%

“…Geochemical analysis of samples collected at Blood Falls allows us to infer the "purity" of our samples from the subglacial source. The chemistry of subglacial brine released at Blood Falls is markedly different from the chemistry of Taylor Glacier ice and the other streams that derive from supraglacial melt during the austral summer (42,43). The chemistry of Blood Falls can vary with the rate of subglacial discharge, with low-discharge waters being diluted with contemporary glacial surface melt.…”

Section: Resultsmentioning

confidence: 97%

“…Ice-penetrating-radar data indicate water or slush below the glacier corresponding to an 80-m depression in the bedrock topology at ϳ4 km up-glacier from the terminus (28). This depression is below sea level and forms what is believed to have been a third lobe of Lake Bonney (43). When the chemically reduced subglacial brine flows from below the glacier and is exposed to the atmosphere, it becomes oxidized and a red salt cone, known as Blood Falls, precipitates at the northern end of the glacier terminus ( Fig.…”

mentioning

confidence: 99%

“…The subglacial brine is thought to be a remnant of seawater originating from the last marine incursion into the McMurdo Dry Valley network during the Pliocene Epoch (ϳ5 million years ago), when the Dry Valleys were fjord lands (17). Although geochemical studies of the subglacial outflow have been conducted sporadically since the early 1960s (4,6,35,43), our study is the first to investigate the microbial diversity associated with Blood Falls. (Fig.…”

mentioning

confidence: 99%

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Bacterial Diversity Associated with Blood Falls, a Subglacial Outflow from the Taylor Glacier, Antarctica

Mikucki

Priscu

2007

Appl Environ Microbiol

167

133

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Blood Falls is the surface manifestation of brine released from below the Taylor Glacier, McMurdo Dry Valleys, Antarctica. Geochemical analyses of Blood Falls show that this brine is of a marine origin. The discovery that 74% of clones and isolates from Blood Falls share high 16S rRNA gene sequence homology with phylotypes from marine systems supports this contention. The bacterial 16S rRNA gene clone library was dominated by a phylotype that had 99% sequence identity with Thiomicrospira arctica (46% of the library), a psychrophilic marine autotrophic sulfur oxidizer. The remainder of the library contained phylotypes related to the classes Betaproteobacteria, Deltaproteobacteria, and Gammaproteobacteria and the division Bacteroidetes and included clones whose closest cultured relatives metabolize iron and sulfur compounds. These findings are consistent with the high iron and sulfate concentrations detected in Blood Falls, which are likely due to the interactions of the subglacial brine with the underlying iron-rich bedrock. Our results, together with previous reports, suggest that the brine below the Taylor Glacier hosts a viable ecosystem with microorganisms capable of growth, supported by chemical energy present in reduced iron and sulfur compounds. The metabolic and phylogenetic structure of this subglacial microbial assemblage appears to be controlled by glacier hydrology, bedrock lithology, and the preglacial ecosystem.Recent changes in our understanding of subglacial environments have led scientists to investigate the role of microorganisms in subglacial processes (65). Though these processes were once thought to be devoid of microbially mediated reactions (51), it is now clear that microorganisms contribute to subglacial weathering and carbon cycling (e.g., references 24, 47, 58, 60, 61, and 68). A growing consensus among these studies is that there is a strong link between geochemical signatures in subglacial materials and the metabolic processes present. The physical isolation, constant low temperatures, and permanent darkness of the subglacial environment make subglacial systems ideal sites for studying the relationship between microbial diversity and ecosystem function.Measurements of diversity in a particular habitat establish the community structure in which the functional or ecological niches of the system are filled (5). Emerging themes in the ecology of the subglacial ecosystem are that glacier hydrology and bedrock lithology control microbial community structure (60, 65). The niche space generated by these controlling factors would clearly affect metabolic community structure by influencing electron acceptor and donor availability in the subglacial setting.

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supporting

confidence: 64%

Section: Resultsmentioning

confidence: 97%

mentioning

confidence: 99%

mentioning

confidence: 99%

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Bacterial Diversity Associated with Blood Falls, a Subglacial Outflow from the Taylor Glacier, Antarctica

Mikucki

Priscu

2007

Appl Environ Microbiol

167

133

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“…The lake occupies a closed basin; meltwater streams flow into the lake during summer, but water is lost only through ablation of ice from the surface and water evaporation from a summer "moat" of melt water around the margins of the lake (Lawrence and Hendy, 1985). Historical imbalances in water supply and loss resulted in evaporation and refilling events, creating density stratification of the lake due to increasing salinity with depth (Lyons et al, 2005). This stratification inhibits as doi:10.1130/G36966.1 Geology, published online on 21 August 2015 mixing, as does the permanent ice cover; solute transport below 5 m is dominated by diffusion.…”

Section: Lake Fryxellmentioning

confidence: 99%

Antarctic microbial mats: A modern analog for Archean lacustrine oxygen oases

Sumner

Hawes

Mackey

et al. 2015

Geology

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The evolution of oxygenic photosynthesis was the most important geochemical event in Earth history, causing the Great Oxidation Event (GOE) ~2.4 b.y. ago. However, evidence is mixed as to whether O 2 production occurred locally as much as 2.8 b.y. ago, creating O 2 oases, or initiated just prior to the GOE. The biogeochemical dynamics of possible O 2 oases have been poorly constrained due to the absence of modern analogs. However, cyanobacteria in microbial mats in a perennially anoxic region of Lake Fryxell, Antarctica, create a 1-2 mm O 2 -containing layer in the upper mat during summer, providing the first known modern analog for formation of benthic O 2 oases. In Lake Fryxell, benthic cyanobacteria are present below the oxycline in the lake. Mat photosynthesis rates were slow due to low photon flux rate (1-2 µmol m -2 s -1) under thick ice cover, but photosynthetic O 2 production was sufficient to sustain up to 50 µmol O 2 L -1

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Subsurface imaging reveals a confined aquifer beneath an ice-sealed Antarctic lake

Dugan

Doran

Tulaczyk

et al. 2015

Geophys. Res. Lett.

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Liquid water oases are rare under extreme cold desert conditions found in the AntarcticMcMurdo Dry Valleys. Here we report geophysical results that indicate that Lake Vida, one of the largest lakes in the region, is nearly frozen and underlain by widespread cryoconcentrated brine. A ground penetrating radar survey profiled 20 m into lake ice and facilitated bathymetric mapping of the upper lake basin. An airborne transient electromagnetic survey revealed a low-resistivity zone 30-100 m beneath the lake surface. Based on previous knowledge of brine chemistry and local geology, we interpret this zone to be a confined aquifer situated in sediments with a porosity of 23-42%. Discovery of this aquifer suggests that subsurface liquid water may be more pervasive in regions of continuous permafrost than previously thought and may represent an extensive habitat for microbial populations.

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Halogen geochemistry of the McMurdo dry valleys lakes, Antarctica: Clues to the origin of solutes and lake evolution

Cited by 72 publications

References 86 publications

Bacterial Diversity Associated with Blood Falls, a Subglacial Outflow from the Taylor Glacier, Antarctica

Bacterial Diversity Associated with Blood Falls, a Subglacial Outflow from the Taylor Glacier, Antarctica

Antarctic microbial mats: A modern analog for Archean lacustrine oxygen oases

Subsurface imaging reveals a confined aquifer beneath an ice-sealed Antarctic lake

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