Patterns and Processes of Salt Efflorescences in the McMurdo region, Antarctica

Bisson, Kelsey; Welch, Kathleen A.; Welch, Susan A.; Sheets, J.; Lyons, W. Berry; Levy, Joseph S.; Fountain, Andrew G.

doi:10.1657/aaar0014-024

Cited by 20 publications

(27 citation statements)

References 38 publications

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“…Though there was gypsum observed in grain etch pits from SEM imaging (Figure d), it was not the only salt present at East Lake Bonney, and the leachate from these samples suggests that Cl − is the dominate anion, not SO 4 2− . Bisson et al () also observed sodium bicarbonate in Taylor Valley soils, which may contribute a minor amount of bicarbonate salts to these samples. In general, these studies agreed with the earlier work on MDV soils by Keys and Williams (), who first described the trends of soluble salts in Taylor Valley soils.…”

Section: Discussionmentioning

confidence: 81%

“…The strong association between Na + and Cl − concentrations in F6 and Explorer's Cove samples suggests that these ions are from NaCl dissolution (Figures and ). The noncoastal sites have more Na + and Ca 2+ compared to Cl − and HCO 3 − , likely from sodium and calcium sulfate salts, such as gypsum, mirabilite, and glauberite (Figure ; Bisson et al, ). Nearly all samples, regardless of location, have Na + concentrations above the NaCl dissolution line (Figure ), suggesting a relative enrichment of Na + relative to Cl − .…”

Section: Discussionmentioning

confidence: 99%

“…This relationship was also observed for aeolian samples collected at 30 cm above the surface by Deuerling et al (). Mirabilite is a ubiquitous salt phase within MDV soils (Bisson et al, ), so the additional Na + is thought to be in part from this source (Figure ). Since F6 and Explorer's Cove plot directly on the combined halite and calcium carbonate dissolution line (Figure ), it is possible that some of the Na + is from the dissolution of sodium bicarbonate (NaHCO 3 ), which Toner et al () believes could form in Eastern Taylor Valley soils (i.e., Fryxell and Hoare basins) due to the relatively higher soil moisture content.…”

Section: Discussionmentioning

confidence: 99%

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Aeolian Material Transport and Its Role in Landscape Connectivity in the McMurdo Dry Valleys, Antarctica

et al. 2018

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Arid regions, particularly polar and alpine desert environments, have diminished landscape connectivity compared to temperate regions due to limited and/or seasonal hydrological processes. For these environments, aeolian processes play a particularly important role in landscape evolution and biotic community vitality through nutrient and solute additions. The McMurdo Dry Valleys (MDV) are the largest ice‐free area in Antarctica and are potentially a major source of aeolian material for the continent. From this region, samples were collected at five heights (~5, 10, 20, 50, and 100 cm) above the surface seasonally for 2013 through 2015 from Alatna Valley, Victoria Valley, Miers Valley, and Taylor Valley (Taylor Glacier, East Lake Bonney, F6 (Lake Fryxell), and Explorer's Cove). Despite significant geological separation and varying glacial histories, low‐elevation and coastal sites had similar major ion chemistries, as did high‐elevation and inland locations. This locational clustering of compositions was also evident in scanning electron microscopy images and principal component analyses, particularly for samples collected at ~100 cm above the surface. Compared to published soil literature, aeolian material in Taylor Valley demonstrates a primarily down‐valley transport of material toward the coast. Soluble N:P ratios in the aeolian material reflect relative nutrient enrichments seen in MDV soils and lakes, where younger, coastal soils are relatively N depleted, while older, up‐valley soils are relatively P depleted. The aeolian transport of materials, including water‐soluble nutrients, is an important vector of connectivity within the MDV and provides a mechanism to help “homogenize” the geochemistry of both soil and aquatic ecosystems.

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Section: Discussionmentioning

confidence: 81%

Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

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Aeolian Material Transport and Its Role in Landscape Connectivity in the McMurdo Dry Valleys, Antarctica

et al. 2018

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“…A large portion of DIN supplied to meltwaters in the ice‐marginal system may be sourced from the dissolution of nitrogen‐containing salts. Low precipitation rates, humidity, and overland flow allow salts to accumulate in Dry Valley soils, similar to other arid regions where evaporation and sublimation exceed precipitation (Bisson et al, ). Nitrates of sodium and magnesium, including Darapskite (Na 3 NO 3 SO 4 H 2 O) and soda niter (NaNO 3 ), are widespread in South Victoria Land (Claridge and Campbell, ; Keys and Williams, ), are highly soluble and, if present, could readily contribute NO 3 − to meltwaters.…”

Section: Discussionmentioning

confidence: 92%

Trickle or treat: The dynamics of nutrient export from polar glaciers

et al. 2017

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Cold‐based polar glacier watersheds contain well‐defined supraglacial, ice‐marginal, and proglacial elements that differ in their degree of hydrologic connectivity, sources of water (e.g., snow, ice, and/or sediment pore water), meltwater residence times, allochthonous and autochthonous nutrient, and sediment loads. We investigated 11 distinct hydrological units along the supraglacial, ice marginal, and proglacial flow paths that drain Joyce Glacier in the McMurdo Dry Valleys of Antarctica. We found that these units play unique and important roles as sources and/or sinks for dissolved inorganic nitrogen and dissolved inorganic phosphorus and for specific fractions of dissolved organic matter (DOM) as waters are routed from the glacier into nutrient‐poor downstream ecosystems. Changes in nutrient export from the glacial system as a whole were observed as the routing and residence times of meltwater changed throughout the melt season. The concentrations of major ions in the proglacial stream were inversely proportional to discharge, such that there was a relatively constant “trickle” of these solutes into downstream ecosystems. In contrast, NO3− concentrations generally increased with discharge, resulting in delivery of episodic pulses of dissolved inorganic nitrogen‐rich water (“treats”) into those same ecosystems during high discharge events. DOM concentrations or fluorescence did not correlate with discharge rate, but high variability in DOM concentrations or fluorescence suggests that DOM may be exported downstream as episodic treats, but with spatial and/or temporal patterns that remain poorly understood. The strong, nutrient‐specific responses to changes in hydrology suggest that polar glacier drainage systems may export meltwater with nutrient compositions that vary within and between melt seasons and watersheds. Because nutrient dynamics identified in this study differ between glacier watersheds with broadly similar hydrology, climate, and geology, we emphasize the need to develop conceptual models of nutrient export that thoroughly integrate the biogeochemical and hydrological processes that control the sources, fate, and export of nutrients from each system.

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“…Some studies also reported a high flux of cations (e.g., K + and Ca 2+ ) and relatively low silica flux in polar regions [8]. In previous studies, many factors such as rapid runoff, salt weathering, and micro-organisms have been suggested to promote chemical weathering in polar regions [10][11][12]. Moreover, some studies emphasized the importance of moisture availability to chemical weathering in these regions [13,14].…”

Section: Introductionmentioning

confidence: 98%

Chemical Weathering of Granite in Ice and Its Implication for Weathering in Polar Regions

et al. 2020

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Recently, it has been reported that some chemical reactions are enhanced in below-freezing conditions. Despite the high denudation typical of polar regions, chemical weathering that occurs under ice has not been investigated. In this study, we investigated the dissolution of granite in ice. The mixture of granite and deionized water (DW) or solution adjusted to pH 2 or 3 was split into two groups: the test group was frozen at −20 °C, while the control was maintained at room temperature. After 29 days of batch experiments, the filtrate was analyzed to measure the concentrations of cations and silica. The filtered powder was analyzed to investigate the mineral compositions and crystallinities of the granite before and after the experiments. Despite the low temperature, a significant quantity of cations (Na+, K+, Mg2+, Ca2+) were dissolved out, even from the ice samples. During X-ray diffraction (XRD) analysis, the decreased crystallinities of granite in ice samples were identified regardless of the pH condition. To verify the observed freeze concentration effect, the concentration of granite in the ice grain boundaries was observed using optical microscopy with a cold chamber. The low concentration of silica in the ice samples could explain the silica anomaly in polar regions. This study also provides a new perspective for the dissolution mechanism in polar regions.

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Patterns and Processes of Salt Efflorescences in the McMurdo region, Antarctica

Cited by 20 publications

References 38 publications

Aeolian Material Transport and Its Role in Landscape Connectivity in the McMurdo Dry Valleys, Antarctica

Aeolian Material Transport and Its Role in Landscape Connectivity in the McMurdo Dry Valleys, Antarctica

Trickle or treat: The dynamics of nutrient export from polar glaciers

Chemical Weathering of Granite in Ice and Its Implication for Weathering in Polar Regions

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