02600nas a2200217 4500008004100000245010600041210006900147260001200216490000700228520191500235653001502150653001802165653001602183653002202199653001702221100002202238700001702260700002102277700001702298856006702315 2021 eng d00aAntarctic water tracks: Microbial community responses to variation in soil moisture, pH, and salinity0 aAntarctic water tracks Microbial community responses to variatio c01/20210 v123 a
Ice-free soils in the McMurdo Dry Valleys select for taxa able to cope with challenging environmental conditions, including extreme chemical water activity gradients, freeze-thaw cycling, desiccation, and solar radiation regimes. The low biotic complexity of Dry Valley soils makes them well suited to investigate environmental and spatial influences on bacterial community structure. Water tracks are annually wetted habitats in the cold-arid soils of Antarctica that form briefly each summer with moisture sourced from snow melt, ground ice thaw, and atmospheric deposition via deliquescence and vapor flow into brines. Compared to neighboring arid soils, water tracks are highly saline and relatively moist habitats. They represent a considerable area (∼5–10 km2) of the Dry Valley terrestrial ecosystem, an area that is expected to increase with ongoing climate change. The goal of this study was to determine how variation in the environmental conditions of water tracks influences the composition and diversity of microbial communities. We found significant differences in microbial community composition between on- and off-water track samples, and across two distinct locations. Of the tested environmental variables, soil salinity was the best predictor of community composition, with members of the Bacteroidetes phylum being relatively more abundant at higher salinities and the Actinobacteria phylum showing the opposite pattern. There was also a significant, inverse relationship between salinity and bacterial diversity. Our results suggest water track formation significantly alters dry soil microbial communities, likely influencing subsequent ecosystem functioning. We highlight how Dry Valley water tracks could be a useful model system for understanding the potential habitability of transiently wetted environments found on the surface of Mars.
10aAntarctica10aextremophiles10aMars analog10amicrobial ecology10awater tracks1 aGeorge, Scott, F.1 aFierer, Noah1 aLevy, Joseph, S.1 aAdams, Byron uhttps://www.frontiersin.org/articles/10.3389/fmicb.2021.61673002093nas a2200205 4500008004100000022001400041245013400055210006900189260001200258300000900270520139200279653001801671653001401689653001701703653002101720653001301741653001901754100002101773856009301794 2021 eng d a0954-102000aEpisodic basin-scale soil moisture anomalies associated with high relative humidity events in the McMurdo Dry Valleys, Antarctica0 aEpisodic basinscale soil moisture anomalies associated with high c08/2021 a1-153 aOutside of hydrologically wetted active layer soils and humidity-sensitive soil brines, low soil moisture is a limiting factor controlling biogeochemical processes in the McMurdo Dry Valleys. But anecdotal field observations suggest that episodic wetting and darkening of surface soils in the absence of snowmelt occurs during high humidity conditions. Here, I analyse long-term meteorological station data to determine whether soil-darkening episodes are present in the instrumental record and whether they are, in fact, correlated with relative humidity. A strong linear correlation is found between relative humidity and soil reflectance at the Lake Bonney long-term autonomous weather station. Soil reflectance is found to decrease annually by a median of 27.7% in response to high humidity conditions. This magnitude of darkening is consistent with soil moisture rising from typical background values of < 0.5 wt.% to 2–3 wt.%, suggesting that regional atmospheric processes may result in widespread soil moisture generation in otherwise dry surface soils. Temperature and relative humidity conditions under which darkening is observed occur for hundreds of hours per year, but are dominated by episodes occurring between midnight and 07h00 local time, suggesting that wetting events may be common, but are not widely observed during typical diel science operations.
10adeliquescence10ahydrology10amicroclimate10amicrometeorology10apedology10aremote sensing1 aLevy, Joseph, S. uhttps://www.cambridge.org/core/product/identifier/S0954102021000341/type/journal_article01634nas a2200217 4500008004100000245010200041210006900143260001200212300001400224490000600238520092200244100002401166700002901190700002201219700002101241700002501262700002401287700001301311700002101324856007101345 2017 eng d00aHigh-resolution elevation mapping of the McMurdo Dry Valleys, Antarctica, and surrounding regions0 aHighresolution elevation mapping of the McMurdo Dry Valleys Anta c07/2017 a435 - 4430 v93 aWe present detailed surface elevation measurements for the McMurdo Dry Valleys, Antarctica derived from aerial lidar surveys flown in the austral summer of 2014–2015 as part of an effort to understand geomorphic changes over the past decade. Lidar return density varied from 2 to > 10 returns m−2 with an average of about 5 returns m−2. Vertical and horizontal accuracies are estimated to be 7 and 3 cm, respectively. In addition to our intended targets, other ad hoc regions were also surveyed including the Pegasus flight facility and two regions on Ross Island, McMurdo Station, Scott Base (and surroundings), and the coastal margin between Cape Royds and Cape Evans. These data are included in this report and data release. The combined data are freely available at https://doi.org/10.5069/G9D50JX3.
1 aFountain, Andrew, G1 aFernandez-Diaz, Juan, C.1 aObryk, Maciek, K.1 aLevy, Joseph, S.1 aGooseff, Michael, N.1 aVan Horn, David, J.1 aMorin, P1 aShrestha, Ramesh uhttps://www.earth-syst-sci-data.net/9/435/2017/essd-9-435-2017.pdf02255nas a2200193 4500008004100000245007900041210006900120260001200189300001400201490000800215520163600223100002001859700002501879700002401904700002101928700002201949700002401971856006601995 2017 eng d00aImpacts of permafrost degradation on a stream in Taylor Valley, Antarctica0 aImpacts of permafrost degradation on a stream in Taylor Valley A c05/2017 a205 - 2130 v2853 aThe McMurdo Dry Valleys (MDV) of Antarctica are an ice-free landscape that supports a complex, microbially dominated ecosystem despite a severely arid, cold environment (b 5 cm water equivalent/y, − 18 °C mean annual air temperature). Recent observations of permafrost degradation in the coastal zones of the MDV suggest that this region is nearing a threshold of rapid landscape change. In 2012, substantial thermokarst development was observed along several kilometers of the west branch of Crescent Stream in Taylor Valley mostly in the form of bank failures, whereas the adjacent east branch was unaffected. The objective of this study was to quantify the changes to the stream banks of the west branch of Crescent Stream and to determine the impacts on the composition of the stream bed material. Three annually repeated terrestrial LiDAR scans were compared to determine the rates of ground surface change caused by thermokarst formation on the stream bank. The areal extent of the thermokarst was shown to be decreasing; however, the average vertical rate of retreat remained constant. Field measurements of bed materials indicated that the west branch and the reach downstream of the confluence (of east and west branches) consistently contained more fines than the unaffected east branch. This suggests that the finer bed material is a result of the thermokarst development on the west branch. These finer bed material compositions are likely to increase the mobility of the bed material, which will have implications for stream morphology, stream algal mat communities, and downstream aquatic ecosystems.
1 aSudman, Zachary1 aGooseff, Michael, N.1 aFountain, Andrew, G1 aLevy, Joseph, S.1 aObryk, Maciek, K.1 aVan Horn, David, J. uhttp://linkinghub.elsevier.com/retrieve/pii/S0169555X1630846701522nas a2200181 4500008004100000022001400041245007100055210006900126260001200195300001400207490000700221520096100228100002101189700002401210700001701234700002401251856006501275 2015 eng d a0954-102000aExperimental formation of pore fluids in McMurdo Dry Valleys soils0 aExperimental formation of pore fluids in McMurdo Dry Valleys soi c04/2015 a163 - 1710 v273 aThe aim of the study was to determine if soil salt deliquescence and brine hydration can occur under laboratory conditions using natural McMurdo Dry Valleys soils. The experiment was a laboratory analogue for the formation of isolated patches of hypersaline, damp soil, referred to as ‘wet patches’. Soils were oven dried and then hydrated in one of two humidity chambers: one at 100% relative humidity and the second at 75% relative humidity. Soil hydration is highly variable, and over the course of 20 days of hydration, ranged from increases in water content by mass from 0–16% for 122 soil samples from Taylor Valley. The rate and absolute amount of soil hydration correlates well with the soluble salt content of the soils but not with grain size distribution. This suggests that the formation of bulk pore waters in these soils is a consequence of salt deliquescence and hydration of the brine from atmospheric water vapour.
1 aLevy, Joseph, S.1 aFountain, Andrew, G1 aLyons, Berry1 aWelch, Kathleen, A. uhttp://www.journals.cambridge.org/abstract_S095410201400047906572nas a2200169 4500008004100000245008400041210006900125520601300194100001906207700002406226700001506250700001906265700001706284700002106301700002406322856005606346 2015 eng d00aPatterns and processes of salt efflorescences in the McMurdo region, Antarctica0 aPatterns and processes of salt efflorescences in the McMurdo reg3 aEvaporite salts are abundant around the McMurdo region, Antarctica (~78°S) due to very low precipitation, low relative humidity, and limited overland flow. Hygroscopic salts in the McMurdo Dry Valleys (MDVs) are preferentially formed in locations where liquid water is present in the austral summer, including along ephemeral streams, ice-covered lake boundaries, or shallow groundwater tracks. In this study, we collected salts from the Miers, Garwood, and Taylor Valleys on the Antarctic continent, as well as around McMurdo Station on Ross Island in close proximity to water sources with the goal of understanding salt geochemistry in relationship to the hydrology of the area. Halite is ubiquitous; sodium is the major cation (ranging from 70%–90% of cations by meq kg−1 sediment) and chloride is the major anion (>50%) in nearly all samples. However, a wide variety of salt phases and morphologies are tentatively identified through scanning electron microscopy (SEM) and X-ray diffraction (XRD) work. We present new data that identifies trona (Na3(CO3)(HCO3)·2H2O), tentative gaylussite (Na2Ca(CO3)2·5H2O), and tentative glauberite (Na2Ca(SO4)2) in the MDV, of which the later one has not been documented previously. Our work allows for the evaluation of processes that influence brine evolution on a local scale, consequently informing assumptions underlying large-scale processes (such as paleoclimate) in the MDV. Hydrological modeling conducted in FREZCHEM and PHREEQC suggests that a model based on aerosol deposition alone in low elevations on the valley floor inadequately characterizes salt distributions found on the surfaces of the soil because it does not account for other hydrologic inputs/outputs. Implications for the salt distributions include their use as tracers for paleolake levels, geochemical tracers of ephemeral water tracks or “wet patches” in the soil, indicators of chemical weathering products, and potential delineators of ecological communities.
1 aBisson, K., M.1 aWelch, Kathleen, A.1 aWelch, Sue1 aSheets, J., M.1 aLyons, Berry1 aLevy, Joseph, S.1 aFountain, Andrew, G uhttp://aaarjournal.org/doi/abs/10.1657/AAAR0014-02401695nas a2200181 4500008004100000022001400041245013500055210006900190260001200259300001400271490000700285520107500292100002101367700001601388700002401404700002001428856006501448 2014 eng d a0954-102000aHyperspectral measurements of wet, dry and saline soils from the McMurdo Dry Valleys: soil moisture properties from remote sensing0 aHyperspectral measurements of wet dry and saline soils from the c10/2014 a565 - 5720 v263 aSoil moisture is a spatially heterogeneous quantity in the McMurdo Dry Valleys of Antarctica that exerts a large influence on the biological community and on the thermal state of Dry Valleys permafrost. The goal of this project was to determine whether hyperspectral remote sensing techniques could be used to determine soil moisture conditions in the Dry Valleys. We measured the spectral reflectance factors of wetted soil samples from the Dry Valleys under natural light conditions and related diagnostic spectral features to surface layer soil moisture content. Diagnostic water absorption features in the spectra at 1.4 µm and 1.9 µm were present in all samples, including samples doped with high concentrations of chloride salts. The depth of the 1.4 µm absorption is shown to increase linearly with increasing gravimetric water content. These results suggest that airborne hyperspectral imaging of the Dry Valleys could generate soil moisture maps of this environment over large spatial areas using non-invasive remote-sensing techniques.
1 aLevy, Joseph, S.1 aNolin, Anne1 aFountain, Andrew, G1 aHead, James, W. uhttp://www.journals.cambridge.org/abstract_S095410201300097702542nas a2200181 4500008004100000022001300041245006800054210006300122260001200185300001200197490000800209520181900217100002402036700002102060700002502081700002402106856023002130 2014 eng d a0169555X00aThe McMurdo Dry Valleys: A landscape on the threshold of change0 aMcMurdo Dry Valleys A landscape on the threshold of change c11/2014 a25 - 350 v2253 aField observations of coastal and lowland regions in the McMurdo Dry Valleys suggest they are on the threshold of rapid topographic change, in contrast to the high elevation upland landscape that represents some of the lowest rates of surface change on Earth. A number of landscapes have undergone dramatic and unprecedented landscape changes over the past decade including, the Wright Lower Glacier (Wright Valley) — ablated several tens of meters, the Garwood River (Garwood Valley) has incised > 3 m into massive ice permafrost, smaller streams in Taylor Valley (Crescent, Lawson, and Lost Seal Streams) have experienced extensive down-cutting and/or bank undercutting, and Canada Glacier (Taylor Valley) has formed sheer, > 4 meter deep canyons. The commonality between all these landscape changes appears to be sediment on ice acting as a catalyst for melting, including ice-cement permafrost thaw. We attribute these changes to increasing solar radiation over the past decade despite no significant trend in summer air temperature. To infer possible future landscape changes in the McMurdo Dry Valleys, due to anticipated climate warming, we map ‘at risk’ landscapes defined as those with buried massive ice in relative warm regions of the valleys. Results show that large regions of the valley bottoms are ‘at risk’. Changes in surface topography will trigger important responses in hydrology, geochemistry, and biological community structure and function.
1 aFountain, Andrew, G1 aLevy, Joseph, S.1 aGooseff, Michael, N.1 aVan Horn, David, J. uhttp://linkinghub.elsevier.com/retrieve/pii/S0169555X14001780http://api.elsevier.com/content/article/PII:S0169555X14001780?httpAccept=text/xmlhttp://api.elsevier.com/content/article/PII:S0169555X14001780?httpAccept=text/plain00634nas a2200181 4500008004100000245007700041210006900118260001200187490000600199100002100205700002400226700002300250700002000273700001900293700002400312700002000336856009600356 2013 eng d00aAccelerated thermokarst formation in the McMurdo Dry Valleys, Antarctica0 aAccelerated thermokarst formation in the McMurdo Dry Valleys Ant c07/20130 v31 aLevy, Joseph, S.1 aFountain, Andrew, G1 aDickson, James, L.1 aHead, James, W.1 aOkal, Marianne1 aMarchant, David, R.1 aWatters, Jaclyn uhttp://www.nature.com/srep/2013/130724/srep02269/full/srep02269.html?WT.ec_id=SREP-2013073000625nas a2200145 4500008004100000245013000041210006900171260001100240490000600251100002300257700002000280700002100300700002400321856013400345 2013 eng d00aCORRIGENDUM: Don Juan Pond, Antarctica: Near-surface CaCl2-brine feeding Earth’s most saline lake and implications for Mars0 aCORRIGENDUM Don Juan Pond Antarctica Nearsurface CaCl2brine feed c3/20130 v31 aDickson, James, L.1 aHead, James, W.1 aLevy, Joseph, S.1 aMarchant, David, R. uhttps://mcm.lternet.edu/content/corrigendum-don-juan-pond-antarctica-near-surface-cacl2-brine-feeding-earth%E2%80%99s-most-saline00577nas a2200145 4500008004100000245011500041210006900156260001200225490000600237100002300243700002000266700002100286700002400307856010000331 2013 eng d00aDon Juan Pond, Antarctica: Near-surface CaCl2-brine feeding Earth's most saline lake and implications for Mars0 aDon Juan Pond Antarctica Nearsurface CaCl2brine feeding Earths m c01/20130 v31 aDickson, James, L.1 aHead, James, W.1 aLevy, Joseph, S.1 aMarchant, David, R. uhttp://www.nature.com/srep/2013/130130/srep01166/full/srep01166.html?WT.ec_id=SREP-704-2013020100638nas a2200169 4500008004100000245013200041210006900173260001200242300001600254490000800270100002100278700002400299700002100323700002400344700001700368856008300385 2013 eng d00aGarwood Valley, Antarctica: A new record of Last Glacial Maximum to Holocene glaciofluvial processes in the McMurdo Dry Valleys0 aGarwood Valley Antarctica A new record of Last Glacial Maximum t c09/2013 a1484 - 15020 v1251 aLevy, Joseph, S.1 aFountain, Andrew, G1 aO'Connor, J., E.1 aWelch, Kathleen, A.1 aLyons, Berry uhttp://bulletin.geoscienceworld.org/content/early/2013/06/07/B30783.1.abstract00495nas a2200121 4500008004100000245009100041210006900132260001200201300001400213490000700227100002100234856011800255 2013 eng d00aHow big are the McMurdo Dry Valleys? Estimating ice-free area using Landsat image data0 aHow big are the McMurdo Dry Valleys Estimating icefree area usin c02/2013 a119 - 1200 v251 aLevy, Joseph, S. uhttps://mcm.lternet.edu/content/how-big-are-mcmurdo-dry-valleys-estimating-ice-free-area-using-landsat-image-data00493nas a2200145 4500008004100000245007100041210006900112260001200181300001400193490000700207100002500214700002200239700002100261856006500282 2013 eng d00aShallow groundwater systems in a polar desert, McMurdo Dry Valleys0 aShallow groundwater systems in a polar desert McMurdo Dry Valley c02/2013 a171 - 1830 v211 aGooseff, Michael, N.1 aBarrett, John, E.1 aLevy, Joseph, S. uhttp://link.springer.com/article/10.1007%2Fs10040-012-0926-300488nas a2200145 4500008004100000245007700041210006900118260001200187300001200199490000700211100002100218700001700239700001700256856006900273 2013 eng d00aUnderstanding Terrestrial Ecosystem Response to Antarctic Climate Change0 aUnderstanding Terrestrial Ecosystem Response to Antarctic Climat c01/2013 a33 - 330 v941 aLevy, Joseph, S.1 aLyons, Berry1 aAdams, Byron uhttp://onlinelibrary.wiley.com/doi/10.1002/2013EO030009/abstract00730nas a2200193 4500008004100000245009900041210006900140300001100209100002100220700002400241700002500265700002200290700002200312700002400334700001700358700002200375700002000397856011900417 2013 eng d00aWater track modification of soil ecosystems in the Lake Hoare basin, Taylor Valley, Antarctica0 aWater track modification of soil ecosystems in the Lake Hoare ba a1 - 101 aLevy, Joseph, S.1 aFountain, Andrew, G1 aGooseff, Michael, N.1 aBarrett, John, E.1 aVantreese, Robert1 aWelch, Kathleen, A.1 aLyons, Berry1 aNielsen, Uffe, N.1 aWall, Diana, H. uhttps://mcm.lternet.edu/content/water-track-modification-soil-ecosystems-lake-hoare-basin-taylor-valley-antarctica00514nas a2200145 4500008004100000245006300041210005600104260001200160490000700172100002100179700002400200700002400224700001700248856010300265 2012 eng d00aHypersaline “wet patches” in Taylor Valley, Antarctica0 aHypersaline wet patches in Taylor Valley Antarctica c03/20120 v391 aLevy, Joseph, S.1 aFountain, Andrew, G1 aWelch, Kathleen, A.1 aLyons, Berry uhttps://mcm.lternet.edu/content/hypersaline-%E2%80%9Cwet-patches%E2%80%9D-taylor-valley-antarctica00630nas a2200169 4500008004100000245013600041210006900177260001200246300001400258490000800272100002100280700002400301700002500325700002400350700001700374856006900391 2011 eng d00aWater tracks and permafrost in Taylor Valley, Antarctica: Extensive and shallow groundwater connectivity in a cold desert ecosystem0 aWater tracks and permafrost in Taylor Valley Antarctica Extensiv c11/2011 a2295-23110 v1231 aLevy, Joseph, S.1 aFountain, Andrew, G1 aGooseff, Michael, N.1 aWelch, Kathleen, A.1 aLyons, Berry uhttp://bulletin.geoscienceworld.org/content/123/11-12/2295.short