TY - JOUR T1 - Barotropic seiches in a perennially ice-covered lake, East Antarctica JF - Limnology and Oceanography Letters Y1 - 2022 A1 - Castendyk, Devin A1 - Hilary A. Dugan A1 - Gallagher, Hugh A. A1 - Pujara, Nimish A1 - Peter T. Doran A1 - John C. Priscu A1 - W. Berry Lyons AB -
Water movement in ice-covered lakes is known to be driven by wind, sediment heat flux, solar radiation, saline density flows, and advective stream discharge. In large ice-covered lakes, wind-induced oscillations have been found to play a major role in horizontal flows. Here, we report recurrent, wind-driven, barotropic seiches in a small lake with a thick (4 m) permanent ice-cover. Between 2010 and 2016, we recorded 10.5- to 13-min oscillations of the hydrostatic water level in Lake Hoare, McMurdo Dry Valleys, East Antarctica, using pressure transducers moored to the lake bottom and suspended from the ice cover. Theoretical calculations showed a barotropic seiche should have a period of 12.6 min. Barotropic seiches were most frequent during high wind events (> 5 m s-1) in winter months (February–November). The period increased during summer months (December–January) when fast ice thinned and melted along the shoreline.
VL - 7 UR - https://aslopubs.onlinelibrary.wiley.com/doi/10.1002/lol2.10226 IS - 1 JO - Limnol Oceanogr Letters ER - TY - JOUR T1 - Elevational constraints on the composition and genomic attributes of microbial communities in Antarctic soils JF - mSystems Y1 - 2022 A1 - Dragone, Nicholas B. A1 - Henley, Jessica B. A1 - Holland-Moritz, Hannah A1 - Melisa A. Diaz A1 - Hogg, Ian D. A1 - W. Berry Lyons A1 - Diana H. Wall A1 - Byron Adams A1 - Noah Fierer ED - Mackelprang, Rachel KW - Antarctica KW - microbial ecology KW - soil microbiology KW - soils AB -The inland soils found on the Antarctic continent represent one of the more challenging environments for microbial life on Earth. Nevertheless, Antarctic soils harbor unique bacterial and archaeal (prokaryotic) communities able to cope with extremely cold and dry conditions. These communities are not homogeneous, and the taxonomic composition and functional capabilities (genomic attributes) of these communities across environmental gradients remain largely undetermined. We analyzed the prokaryotic communities in soil samples collected from across the Shackleton Glacier region of Antarctica by coupling quantitative PCR, marker gene amplicon sequencing, and shotgun metagenomic sequencing. We found that elevation was the dominant factor explaining differences in the structures of the soil prokaryotic communities, with the drier and saltier soils found at higher elevations harboring less diverse communities and unique assemblages of cooccurring taxa. The higher-elevation soil communities also had lower maximum potential growth rates (as inferred from metagenome-based estimates of codon usage bias) and an overrepresentation of genes associated with trace gas metabolism. Together, these results highlight the utility of assessing community shifts across pronounced environmental gradients to improve our understanding of the microbial diversity found in Antarctic soils and the strategies used by soil microbes to persist at the limits of habitability.
VL - 7 UR - https://journals.asm.org/doi/full/10.1128/msystems.01330-21 IS - 1 ER - TY - JOUR T1 - Response of Antarctic soil fauna to climate‐driven changes since the Last Glacial Maximum JF - Global Change Biology Y1 - 2022 A1 - Franco, André L. C. A1 - Byron Adams A1 - Melisa A. Diaz A1 - Lemoine, Nathan P. A1 - Dragone, Nicholas B. A1 - Noah Fierer A1 - W. Berry Lyons A1 - Hogg, Ian D. A1 - Diana H. Wall KW - biodiversity KW - climate change KW - glacial retreat KW - nematodes KW - Shackleton Glacier KW - soil invertebrates AB -Understanding how terrestrial biotic communities have responded to glacial recession since the Last Glacial Maximum (LGM) can inform present and future responses of biota to climate change. In Antarctica, the Transantarctic Mountains (TAM) have experienced massive environmental changes associated with glacial retreat since the LGM, yet we have few clues as to how its soil invertebrate-dominated animal communities have responded. Here, we surveyed soil invertebrate fauna from above and below proposed LGM elevations along transects located at 12 features across the Shackleton Glacier region. Our transects captured gradients of surface ages possibly up to 4.5 million years and the soils have been free from human disturbance for their entire history. Our data support the hypothesis that soils exposed during the LGM are now less suitable habitats for invertebrates than those that have been exposed by deglaciation following the LGM. Our results show that faunal abundance, community composition, and diversity were all strongly affected by climate-driven changes since the LGM. Soils more recently exposed by glacial recession (as indicated by distances from present ice surfaces) had higher faunal abundances and species richness than older exposed soils. Higher abundances of the dominant nematode Scottnema were found in older exposed soils, while Eudorylaimus, Plectus, tardigrades, and rotifers preferentially occurred in more recently exposed soils. Approximately 30% of the soils from which invertebrates could be extracted had only Scottnema, and these single-taxon communities occurred more frequently in soils exposed for longer periods of time. Our structural equation modeling of abiotic drivers highlighted soil salinity as a key mediator of Scottnema responses to soil exposure age. These changes in soil habitat suitability and biotic communities since the LGM indicate that Antarctic terrestrial biodiversity throughout the TAM will be highly altered by climate warming.
VL - 28 UR - https://onlinelibrary.wiley.com/doi/10.1111/gcb.15940 IS - 2 ER - TY - CHAP T1 - Chemical weathering in the McMurdo Dry Valleys, Antarctica T2 - Hydrogeology, Chemical Weathering, and Soil Formation Y1 - 2021 A1 - W. Berry Lyons A1 - Leslie, Deborah L. A1 - Michael N. Gooseff ED - Hunt, Allen ED - Egli, Markus ED - Faybishenko, Boris KW - aluminosilicate weathering KW - CaCO3 dissolution/precipitation KW - chemical weathering KW - hyporheic zone KW - McMurdo Dry Valleys AB -While chemical weathering has not always been considered an active process in the McMurdo Dry Valleys (MDV), Antarctica, long‐term geochemical and hydrological investigations have provided an overall better understanding of chemical weathering in this polar desert environment. Liquid water on the landscape is limited to stream channels as well as shallow subsurface melt features, as there is no overland flow. Stream total suspended sediment loads are low, with the sources of sediment from stream channels, aeolian input, and/or from the surfaces of glaciers. MDV soils contain high concentrations of soluble salts with little clay material, but since absent of water, these soils are a minimal location of chemical weathering. Hyporheic zones exchange water during streamflow, and these areas control the stream geochemistry over various temporal scales. Hyporheic zones promote rapid aluminosilicate weathering by moving dilute glacial meltwater into intimate contact with sediment surfaces. Rapid weathering of the aluminosilicates in the streambed and hyporheic zones is the most plausible explanation for chemostasis observed in these streams, indicating that little to no catchment processes are necessary to explain the observed chemostasis in the MDV. Shallow subsurface waters with distinct geochemical signatures have much higher dissolved Si concentrations than the stream waters and indicate that they are responsible for enhanced aluminosilicate weathering in this polar desert environment. The dissolution of CaCO3 is also a major process in the hyporheic zones as generally the streams are unsaturated with respect to calcite. Cation‐exchange reactions are also important in the evolution from Na‐Cl brines to Ca‐Cl brines within the soil column, while authigenic CaCO3 can both dissolve and precipitate depending on the condition of the system. Recently, stream channel landscapes are changing due to the melting of buried ice, creating thermokarst and water track features, resulting in a sediment and solute influx to the stream.
JF - Hydrogeology, Chemical Weathering, and Soil Formation T3 - Geophysical Monograph Series PB - John Wiley & Sons, Inc. CY - Hoboken, NJ UR - https://agupubs.onlinelibrary.wiley.com/doi/10.1002/9781119563952.ch11 ER - TY - JOUR T1 - Exploring the boundaries of microbial habitability in soil JF - Journal of Geophysical Research: Biogeosciences Y1 - 2021 A1 - Dragone, Nicholas B. A1 - Melisa A. Diaz A1 - Hogg, Ian D. A1 - W. Berry Lyons A1 - W. Andrew Jackson A1 - Diana H. Wall A1 - Adams, Byron J. A1 - Noah Fierer KW - Antarctica KW - astrobiology KW - bacteria KW - extremophiles KW - fungi KW - soils AB -Microbes are widely assumed to be capable of colonizing even the most challenging terrestrial surface environments on Earth given enough time. We would not expect to find surface soils uninhabited by microbes as soils typically harbor diverse microbial communities and viable microbes have been detected in soils exposed to even the most inhospitable conditions. However, if uninhabited soils do exist, we might expect to find them in Antarctica. We analyzed 204 ice-free soils collected from across a remote valley in the Transantarctic Mountains (84–85°S, 174–177°W) and were able to identify a potential limit of microbial habitability. While most of the soils we tested contained diverse microbial communities, with fungi being particularly ubiquitous, microbes could not be detected in many of the driest, higher elevation soils—results that were confirmed using cultivation-dependent, cultivation-independent, and metabolic assays. While we cannot confirm that this subset of soils is completely sterile and devoid of microbial life, our results suggest that microbial life is severely restricted in the coldest, driest, and saltiest Antarctic soils. Constant exposure to these conditions for thousands of years has limited microbial communities so that their presence and activity is below detectable limits using a variety of standard methods. Such soils are unlikely to be unique to the studied region with this work supporting previous hypotheses that microbial habitability is constrained by near-continuous exposure to cold, dry, and salty conditions, establishing the environmental conditions that limit microbial life in terrestrial surface soils.
VL - 126 UR - https://agupubs.onlinelibrary.wiley.com/doi/abs/10.1029/2020JG006052 IS - 6 JO - J Geophys Res Biogeosci ER - TY - JOUR T1 - Geochemical zones and environmental gradients for soils from the central Transantarctic Mountains, Antarctica JF - Biogeosciences Y1 - 2021 A1 - Melisa A. Diaz A1 - Christopher B. Gardner A1 - Welch, Susan A. A1 - W. Andrew Jackson A1 - Adams, Byron J. A1 - Diana H. Wall A1 - Hogg, Ian D. A1 - Noah Fierer A1 - W. Berry Lyons AB -Previous studies have established links between biodiversity and soil geochemistry in the McMurdo Dry Valleys, Antarctica, where environmental gradients are important determinants of soil biodiversity. However, these gradients are not well established in the central Transantarctic Mountains, which are thought to represent some of the least hospitable Antarctic soils. We analyzed 220 samples from 11 ice-free areas along the Shackleton Glacier (~85°S), a major outlet glacier of the East Antarctic Ice Sheet. We established three zones of distinct geochemical gradients near the head of the glacier (upper), its central part (middle), and at the mouth (lower). The upper zone had the highest water-soluble salt concentrations with total salt concentrations exceeding 80 000 µg g-1, while the lower zone had the lowest water-soluble N:P ratios, suggesting that, in addition to other parameters (such as proximity to water and/or ice), the lower zone likely represents the most favorable ecological habitats. Given the strong dependence of geochemistry on geographic parameters, we developed multiple linear regression and random forest models to predict soil geochemical trends given latitude, longitude, elevation, distance from the coast, distance from the glacier, and soil moisture (variables which can be inferred from remote measurements). Confidence in our random forest model predictions was moderately high with R2 values for total water-soluble salts, water-soluble N:P, ClO4-, and ClO3- of 0.81, 0.88, 0.78, and 0.74, respectively. These modeling results can be used to predict geochemical gradients and estimate salt concentrations for other Transantarctic Mountain soils, information that can ultimately be used to better predict distributions of soil biota in this remote region.
VL - 18 UR - https://bg.copernicus.org/articles/18/1629/2021/ IS - 5 JO - Biogeosciences ER - TY - JOUR T1 - Geochemistry of contrasting stream types, Taylor Valley, Antarctica JF - GSA Bulletin Y1 - 2021 A1 - Harmon, Russell S. A1 - Leslie, Deborah L. A1 - W. Berry Lyons A1 - Kathleen A. Welch A1 - Diane M. McKnight AB -The McMurdo Dry Valley region is the largest ice-free area of Antarctica. Ephemeral streams flow here during the austral summer, transporting glacial meltwater to perennially ice-covered, closed basin lakes. The chemistry of 24 Taylor Valley streams was examined over the two-decade period of monitoring from 1993 to 2014, and the geochemical behavior of two streams of contrasting physical and biological character was monitored across the seven weeks of the 2010–2011 flow season. Four species dominate stream solute budgets: HCO3–, Ca2+, Na+, and Cl–, with SO42–, Mg2+, and K+ present in significantly lesser proportions. All streams contain dissolved silica at low concentrations. Across Taylor Valley, streams are characterized by their consistent anionic geochemical fingerprint of HCO3 > Cl > SO4, but there is a split in cation composition between 14 streams with Ca > Na > Mg > K and 10 streams with Na > Ca > Mg > K.
Andersen Creek is a first-order proglacial stream representative of the 13 short streams that flow <1.5 km from source to gage. Von Guerard is representative of 11 long streams 2–7 km in length characterized by extensive hyporheic zones. Both streams exhibit a strong daily cycle for solute load, temperature, dissolved oxygen, and pH, which vary in proportion to discharge. A well-expressed diurnal co-variation of pH with dissolved oxygen is observed for both streams that reflects different types of biological control. The relative consistency of Von Guerard composition over the summer flow season reflects chemostatic regulation, where water in transient storage introduced during times of high streamflow has an extended opportunity for water-sediment interaction, silicate mineral dissolution, and pore-water exchange.
The purpose of this study is to assess the concentrations of Barium (Ba), Copper (Cu), Iron (Fe), Lead (Pb), and Zinc (Zn) in sediment samples obtained from the Wales and Commonwealth streams located in Taylor Valley, Antarctica. These samples were collected at seven sample sites (three in Wales Glacier and four in Commonwealth Glacier) in 0 to 2 cm, 2 to 4 cm, 4 to 6 cm, and 6 to 8 cm depth increments which resulted in 28 total samples. After the collection process, these samples underwent a volumetric 1:5 sediment: 10% HCl leach for 48 hours, filtration through 4-µm pore-size, cellulose acetate membrane filters, and inductively coupled plasma mass spectrometry (ICP-MS) analyses in the Trace Element Research Laboratory at The Ohio State University. Upon completion of the analyses, results showed that the Wales samples had a higher average concentration of every metal element overall and at each depth increment when compared to the Commonwealth samples. In addition to the weak-acid leachate metal analyses, a second aliquot of one sediment profile from each stream was analyzed at Villanova University for the 210Pb activity via gamma spectroscopy. This was done to estimate the sedimentation rates at each of these sites. From the sedimentation rates, sedimentation fluxes were calculated for each element for each sediment profile at each of these sites. The data demonstrated that Fe is the most abundant element while Pb is the least abundant. Lastly, upon examination of results, it was found that the concentrations of these metals are often higher in samples collected closer to the surface. These findings suggest these streams, and their sources, have had little, if any, impact by anthropogenic input of metals, and that metal fluxes to the sediments are low.
JF - School of Earth Sciences PB - The Ohio State University CY - Columbus, OH VL - B.S. UR - http://hdl.handle.net/1811/91772 ER - TY - JOUR T1 - Genetic diversity of soil invertebrates corroborates timing estimates for past collapses of the West Antarctic Ice Sheet JF - Proceedings of the National Academy of Sciences Y1 - 2020 A1 - Gemma E. Collins A1 - Hogg, Ian D. A1 - Convey, Peter A1 - Sancho, Leopoldo G. A1 - Cowan, Don A. A1 - W. Berry Lyons A1 - Byron Adams A1 - Diana H. Wall A1 - Allan Green, T. G. KW - climate change KW - microarthropods KW - molecular clock KW - phylogeography KW - terrestrial biodiversity AB -During austral summer field seasons between 1999 and 2018, we sampled at 91 locations throughout southern Victoria Land and along the Transantarctic Mountains for six species of endemic microarthropods (Collembola), covering a latitudinal range from 76.0°S to 87.3°S. We assembled individual mitochondrial cyto-chrome c oxidase subunit 1 (COI) sequences (n = 866) and found high levels of sequence divergence at both small (<10 km) and large (>600 km) spatial scales for four of the six Collembola species. We applied molecular clock estimates and assessed genetic divergences relative to the timing of past glacial cycles, including collapses of the West Antarctic Ice Sheet (WAIS). We found that genetically distinct lineages within three species have likely been isolated for at least 5.54 My to 3.52 My, while the other three species diverged more recently (<2 My). We suggest that Collembola had greater dispersal opportunities under past warmer climates, via flotation along coastal margins. Similarly increased opportunities for dispersal may occur under contemporary climate warming scenarios, which could influence the genetic structure of extant populations. As Collembola are a living record of past landscape evolution within Antarctica, these findings provide biological evidence to support geological and glaciological estimates of historical WAIS dynamics over the last ca. 5 My.
UR - https://www.pnas.org/content/early/2020/08/19/2007925117 ER - TY - JOUR T1 - Geochemistry of aeolian material from the McMurdo Dry Valleys, Antarctica: Insights into Southern Hemisphere dust sources JF - Earth and Planetary Science Letters Y1 - 2020 A1 - Melisa A. Diaz A1 - Welch, Susan A. A1 - Sheets, J. M. A1 - Kathleen A. Welch A1 - Khan, Alia L. A1 - Byron Adams A1 - Diane M. McKnight A1 - Craig S Cary A1 - W. Berry Lyons KW - aeolian material KW - Antarctica KW - major oxides KW - mineralogy KW - rare earth elements KW - trace elements AB -In the Southern Hemisphere, the major sources of dust and other aeolian materials are from Patagonia, South Africa, Australia, and New Zealand. Dust from Patagonia and New Zealand has been identified in ice cores throughout Antarctica, suggesting that during arid and windy periods, such as glacial periods, dust can be entrained and transported onto the continent. However, little information exists on modern Antarctic dust sources, transport, and its role in the Southern Hemisphere dust cycle. We present the first geochemical characterization of aeolian materials collected at five heights (between 5 cm and 100 cm) above the surface in four valleys within the McMurdo Dry Valleys, the largest ice-free area in Antarctica. Our mineralogy data indicate that these materials are primarily derived from local rocks of the McMurdo Volcanics, Ferrar Dolerite, Beacon Sandstone and Granite Harbor Intrusives, with varying contributions of each rock type dependent on the valley location. While major oxide, trace element and rare earth element data show that low elevation and coastal locations (with respect to the Ross Sea) are dominated by local sources, high elevation and inland locations have accumulated both local materials and dust from other distant Southern Hemisphere sources. This far-traveled material may not be accumulating today, but represents a paleo source that is resuspended from the soils. By geochemically “fingerprinting” aeolian materials from the MDV, we can better inform future studies on the transport of materials within Antarctica and between Southern Hemisphere land masses.
VL - 547 UR - https://www.sciencedirect.com/science/article/pii/S0012821X20304040 ER - TY - JOUR T1 - Silicon isotopes reveal a non-glacial source of silicon to Crescent Stream, McMurdo Dry Valleys, Antarctica JF - Frontiers in Earth Science Y1 - 2020 A1 - Hirst, Catherine A1 - Opfergelt, Sophie A1 - François Gaspard A1 - Hendry, Katharine R. A1 - Hatton, Jade E. A1 - Sue Welch A1 - Diane M. McKnight A1 - W. Berry Lyons AB -In high latitude environments, silicon is supplied to river waters by both glacial and non-glacial chemical weathering. The signal of these two end-members is often obscured by biological uptake and/or groundwater input in the river catchment. McMurdo Dry Valleys streams in Antarctica have no deep groundwater input, no connectivity between streams and no surface vegetation cover, and thus provide a simplified system for us to constrain the supply of dissolved silicon (DSi) to rivers from chemical weathering in a glacial environment. Here we report dissolved Si concentrations, germanium/silicon ratios (Ge/Si) and silicon isotope compositions (δ30SiDSi) in Crescent Stream, McMurdo Dry Valleys for samples collected between December and February in the 2014−2015, 2015−2016, and 2016−2017 austral seasons. The δ30SiDSi compositions and DSi concentrations are higher than values reported in wet-based glacial meltwaters, and form a narrow cluster within the range of values reported for permafrost dominated Arctic Rivers. High δ30SiDSi compositions, ranging from +0.90‰ to +1.39‰, are attributed to (i) the precipitation of amorphous silica during freezing of waters in isolated pockets of the hyporheic zone in the winter and the release of Si from unfrozen pockets during meltwater-hyporheic zone exchange in the austral summer, and (ii) additional Si isotope fractionation via long-term Si uptake in clay minerals and seasonal Si uptake into diatoms superimposed on this winter-derived isotope signal. There is no relationship between δ30SiDSi compositions and DSi concentrations with seasonal and daily discharge, showing that stream waters contain DSi that is in equilibrium with the formation of secondary Si minerals in the hyporheic zone. We show that δ30SiDSi compositions can be used as tracers of silicate weathering in the hyporheic zone and possible tracers of freeze-thaw conditions in the hyporheic zone. This is important in the context of the ongoing warming in McMurdo Dry Valleys and the supply of more meltwaters to the hyporheic zone of McMurdo Dry Valley streams.
VL - 8 UR - https://www.frontiersin.org/articles/10.3389/feart.2020.00229/full ER - TY - JOUR T1 - Silicon isotopic composition of dry and wet-based glaciers in Antarctica JF - Frontiers in Earth Science Y1 - 2020 A1 - Hatton, Jade E. A1 - Hendry, Katharine R. A1 - Hirst, Catherine A1 - Opfergelt, Sophie A1 - Henkel, Susann A1 - Silva-Busso, Adrián A1 - Welch, Susan A. A1 - Wadham, Jemma L. A1 - W. Berry Lyons A1 - Bagshaw, Elizabeth A1 - Staubwasser, Michael A1 - Diane M. McKnight AB -Glaciers and ice sheets export significant amounts of silicon (Si) to downstream ecosystems, impacting local and potentially global biogeochemical cycles. Recent studies have shown Si in Arctic glacial meltwaters to have an isotopically distinct signature when compared to non-glacial rivers. This is likely linked to subglacial weathering processes and mechanochemical reactions. However, there are currently no silicon isotope (δ30Si) data available from meltwater streams in Antarctica, limiting the current inferences on global glacial silicon isotopic composition and its drivers. To address this gap, we present dissolved silicon (DSi), δ30SiDSi, and major ion data from meltwater streams draining a polythermal glacier in the region of the West Antarctic Peninsula (WAP; King George Island) and a cold-based glacier in East Antarctica [Commonwealth Stream, McMurdo Dry Valleys (MDV)]. These data, alongside other global datasets, improve our understanding of how contrasting glacier thermal regime can impact upon Si cycling and therefore the δ30SiDSi composition. We find a similar δ30SiDSi composition between the two sites, with the streams on King George Island varying between -0.23 and +1.23‰ and the Commonwealth stream varying from -0.40 to +1.14‰. However, meltwater streams in King George Island have higher DSi concentrations, and the two glacial systems exhibit opposite DSi – δ30SiDSi trends. These contrasts likely result from differences in weathering processes, specifically the role of subglacial processes (King George Island) and, supraglacial processes followed by in-stream weathering in hyporheic zones (Commonwealth Stream). These findings are important when considering likely changes in nutrient fluxes from Antarctic glaciers under climatic warming scenarios and consequent shifts in glacial thermal regimes.
VL - 8 UR - https://www.frontiersin.org/articles/10.3389/feart.2020.00286/full ER - TY - JOUR T1 - Diurnal chemistry of two contrasting stream types, Taylor Valley, McMurdo Dry Valley Region, Antarctica JF - E3S Web of Conferences Y1 - 2019 A1 - Harmon, Mark E. A1 - Leslie, D.L. A1 - W. Berry Lyons A1 - Kathleen A. Welch A1 - Diane M. McKnight ED - Chudaev, O. ED - Kharaka, Y. ED - Harmon, R.S. ED - Millot, R. ED - Shouakar-Stash, O. AB -Numerous ephemeral streams flow within the McMurdo Dry Valley Region of Antarctica that transport glacial meltwater to perennially ice-covered, closed-basin lakes during the austral summer. The diurnal behavior for two Taylor Valley streams of different character was examined during the summer of 2010-11. Andersen Creek is a short, 1st-order proglacial stream, whereas Von Guerard Stream is a long, high-order stream with an extensive hyporheic zone that has a substantial cyanobacterial algal mat community in its middle reaches. Both streams display strong daily cycles for temperature, electrical conductivity, dissolved oxygen, and pH. Conductivity varies in concert with flow, with solute dilution occurring during the daily high-flow pulse. Dissolved oxygen co-varies strongly with pH at Andersen Creek but not for Von Guerard Stream. Each stream has a distinct geochemical character that for Andersen Creek is a direct reflection of its glacial source, unmodified by secondary effects, whereas that for Von Guerard Stream is modulated by its resident algal mat community and through extensive hyporheic zone interaction and exchange.
VL - 98 UR - https://www.e3s-conferences.org/articles/e3sconf/abs/2019/24/e3sconf_wri-162018_01020/e3sconf_wri-162018_01020.html ER - TY - JOUR T1 - The Geochemistry of Englacial Brine From Taylor Glacier, Antarctica JF - Journal of Geophysical Research: Biogeosciences Y1 - 2019 A1 - W. Berry Lyons A1 - Jill A. Mikucki A1 - German, Laura A. A1 - Kathleen A. Welch A1 - Sue Welch A1 - Christopher B. Gardner A1 - Tulaczyk, Slawek M. A1 - Pettit, Erin C. A1 - Kowalski, Julia A1 - Dachwald, Bernd AB -Blood Falls is a hypersaline, iron‐rich discharge at the terminus of the Taylor Glacier in the McMurdo Dry Valleys, Antarctica. In November 2014, brine in a conduit within the glacier was penetrated and sampled using clean‐entry techniques and a thermoelectric melting probe called the IceMole. We analyzed the englacial brine sample for filterable iron (fFe), total Fe, major cations and anions, nutrients, organic carbon, and perchlorate. In addition, aliquots were analyzed for minor and trace elements and isotopes including δD and δ18O of water, δ34S and δ18O of sulfate, 234U, 238U, δ11B, 87Sr/86Sr, and δ81Br. These measurements were made in order to (1) determine the source and geochemical evolution of the brine and (2) compare the chemistry of the brine to that of nearby hypersaline lake waters and previous supraglacially sampled collections of Blood Falls outflow that were interpreted as end‐member brines. The englacial brine had higher Cl− concentrations than the Blood Falls end‐member outflow; however, other constituents were similar. The isotope data indicate that the water in the brine is derived from glacier melt. The H4SiO4 concentrations and U and Sr isotope suggest a high degree of chemical weathering products. The brine has a low N:P ratio of ~7.2 with most of the dissolved inorganic nitrogen in the form of NH4+. Dissolved organic carbon concentrations are similar to end‐member outflow values. Our results provide strong evidence that the original source of solutes in the brine was ancient seawater, which has been modified with the addition of chemical weathering products.
VL - 124 UR - https://agupubs.onlinelibrary.wiley.com/doi/abs/10.1029/2018JG004411 IS - 3 ER - TY - JOUR T1 - The geochemistry of glacial deposits in Taylor Valley, Antarctica: Comparison to upper continental crustal abundances JF - Applied Geochemistry Y1 - 2019 A1 - Carolyn Dowling A1 - Sue Welch A1 - W. Berry Lyons KW - Antarctica KW - geochemistry KW - glacial deposits KW - polar dry-based glaciers KW - Taylor Valley AB -Wet-based glacial deposits have been used traditionally as an analog for upper continental crust (UCC) abundances. To provide more information on the validity of using glacial deposits from wet-based glaciers, samples deposited by the dry-based polar glaciers located in Taylor Valley, Antarctica, were collected. Stream channel sediments, comprised of igneous, metamorphic, and sedimentary rocks initially deposited as glacial tills by polar glaciers, were analyzed by XRF, ICP-MS, and SEM. Based on the Chemical Index of Alteration values and A–CN–K ternary diagram, there are low levels of chemical weathering in these tills. Additionally, major and trace element geochemical data are compared to the average UCC values. The observed discrepancies between the mean UCC and Antarctic samples develop from the existence of mafic components, most likely the McMurdo Volcanic Group and Ferrar Dolerite, being present in the Taylor Valley tills. Even though the mafic material typically comprises 3–7% of the till, the volcanic rocks have a significant influence on the tills’ bulk geochemistry. The existence of this mafic fraction in the dry-based glacial tills results from the reduced rate of weathering, as compared to wet-based glaciers. Geochemical analyses of the dry-based glacial tills in polar deserts, such as those found in Taylor Valley, may provide a better representative composition of the original material than wet-based glaciers and need to be incorporated into upper continental crust calculations.
UR - https://www.sciencedirect.com/science/article/pii/S0883292719301246 JO - Applied Geochemistry ER - TY - JOUR T1 - The hydroecology of an ephemeral wetland in the McMurdo Dry Valleys, Antarctica JF - Journal of Geophysical Research: Biogeosciences Y1 - 2019 A1 - Wlostowski, Adam A1 - Schulte, Nicholas O. A1 - Byron Adams A1 - Ball, Becky A1 - Rhea M.M. Esposito A1 - Michael N. Gooseff A1 - W. Berry Lyons A1 - Uffe N. Nielsen A1 - Ross A. Virginia A1 - Diana H. Wall A1 - Kathleen A. Welch A1 - Diane M. McKnight KW - Antarctica KW - desert hydrology KW - diatom biodiversity KW - hyporheic interactions KW - wetlands AB -The McMurdo Dry Valleys (MDV) is a polar desert on the coast of East Antarctica where ephemeral wetlands become hydrologically active during warm and sunny summers when sub‐surface flows are generated from melting snowfields. To understand the structure and function of polar wetland ecosystems, we investigated the hydroecology of one such wetland, the Wormherder Creek wetland, during the warm and sunny summer of 2008 – 2009, when the wetland was hydrologically reactivated. Conservative tracer (LiCl) was injected for a 2‐hour period into a stream above the wetland to determine flow path orientations and hydrologic residence times. Tracer results indicated that surface water is rapidly exchanged with wetland groundwater and wetland residence times may exceed two austral summers. Major ion concentrations were uniform in samples from surface water and shallow groundwater throughout the wetland. Microbial mats in the wetland had high autotrophic index values (the ratios of chlorophyll a [Chl‐a]/ash‐free dry mass [AFDM]), ranging from 9‐38 μg Chl‐a/mg AFDM, indicative of actively photosynthesizing mat communities. The diatom communities in the mats were relatively uniform compared to those in mats from regularly flowing MDV streams, with four endemic and one widespread diatom taxa of the genus Luticola accounting for an average of 86% of the community. These results indicate that the hydrologic characteristics of the wetland contribute to uniform geochemical conditions. In turn, uniform geochemical conditions may explain the high autotrophic index values of the microbial mats and relatively low spatial variation of the diatom community.
UR - https://agupubs.onlinelibrary.wiley.com/doi/abs/10.1029/2019JG005153 ER - TY - JOUR T1 - Aeolian material transport and its role in landscape connectivity in the McMurdo Dry Valleys, Antarctica JF - Journal of Geophysical Research: Earth Surface Y1 - 2018 A1 - Melisa A. Diaz A1 - Byron Adams A1 - Kathleen A. Welch A1 - Sue Welch A1 - Opiyo, Stephen O. A1 - Khan, Alia L. A1 - Diane M. McKnight A1 - Craig S Cary A1 - W. Berry Lyons AB -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.
VL - 123 UR - https://agupubs.onlinelibrary.wiley.com/doi/full/10.1029/2017JF004589 IS - 12 JO - J. Geophys. Res. Earth Surf. ER - TY - JOUR T1 - Barium and barite dynamics in Antarctic streams JF - Geology Y1 - 2018 A1 - Saelens, Elsa D. A1 - Christopher B. Gardner A1 - Kathleen A. Welch A1 - Sue Welch A1 - W. Berry Lyons AB -Most natural waters are undersaturated with respect to barite (BaSO4), and while much work has focused on the processes of microbially mediated barite precipitation in undersaturated solutions, particularly in marine environments, little documentation exists on the changes in barite saturation in stream waters. We examined ephemeral glacial meltwater streams in the McMurdo Dry Valleys, Antarctica, that undergo large variations in streamflow and temperature on both a diel and seasonal basis. We measured dissolved Ba in stream water in downstream transects and on a diel cycle, total Ba in stream sediments, algal mats, and lake sediments. Ba concentrations decreased downstream in all four transects, and mineral saturation modeling indicates these waters go from supersaturated to undersaturated with respect to barite in very short distances. Ba is concentrated in stream benthic algal mats at a factor less than observed in marine systems. Both seasonal and diel changes in stream water temperature affect the solubility of barite near glacial sources. Our work shows that both changing stream temperature and the presence of algal materials likely play significant roles in controlling Ba concentrations in polar streams.
VL - 46 UR - https://pubs.geoscienceworld.org/gsa/geology/article/545184/Barium-and-barite-dynamics-in-Antarctic-streams IS - 9 ER - TY - JOUR T1 - Biogeochemical weathering of soil apatite grains in the McMurdo Dry Valleys, Antarctica JF - Geoderma Y1 - 2018 A1 - Heindel, Ruth C A1 - W. Berry Lyons A1 - Sue Welch A1 - Spickard, Angela M A1 - Ross A. Virginia AB -The biogeochemical weathering of the mineral apatite links the lithosphere to the biosphere by releasing the essential nutrient phosphorus (P) into the soil ecosystem. In Taylor Valley, Antarctica, faster rates of apatite weathering may be responsible for the higher concentrations of bioavailable soil P that exist in the Fryxell Basin as compared to the Bonney Basin. In this study, we use scanning electron microscopy to quantify the morphology and surface etching of individual apatite grains to determine whether the degree of apatite weathering differs between the Fryxell and Bonney Basins as well as saturated and dry soil sediments. We show that apatite grains from the Fryxell Basin are rounder, have fewer intact crystal faces, and are more chemically etched than grains from the Bonney Basin. In the Bonney Basin, apatite grains from dry soils show few signs of chemical dissolution, suggesting that soil moisture is a stronger control on the rate of apatite weathering in the Bonney Basin than in the Fryxell Basin. In addition, etch-pit morphologies in the Bonney Basin are more clearly controlled by the hexagonal crystal structure of apatite, while in the Fryxell Basin, etch pits demonstrate a wide range of morphologies without clear crystallographic control. Higher rates of apatite weathering in the Fryxell Basin may be due to the legacy of the physical abrasion of apatite grains during transport by a warm-based ice sheet, as well as the higher levels of precipitation and soil moisture closer to the coast. Our grain-scale approach provides a new perspective on P cycling in the McMurdo Dry Valleys and has implications for apatite weathering and P dynamics in the early stages of soil development.
VL - 320 UR - https://www.sciencedirect.com/science/article/pii/S0016706117320694 JO - Geoderma ER - TY - JOUR T1 - Dissolved Trace and Minor Elements in Cryoconite Holes and Supraglacial Streams, Canada Glacier, Antarctica JF - Frontiers in Earth Science Y1 - 2018 A1 - Sarah Fortner A1 - W. Berry Lyons KW - Antarctica KW - cryoconite holes KW - glacier melt chemistry KW - supraglacial streams KW - trace elements AB -
We present a synthesis of the trace element chemistry in melt on the surface Canada Glacier, Taylor Valley, McMurdo Dry Valleys (MDV), Antarctica (∼78◦S). The MDV is largely ice-free. Low accumulation rates, strong winds, and proximity to the valley floor make these glaciers dusty in comparison to their inland counterparts. This study examines both supraglacial melt streams and cryoconite holes. Supraglacial streams on the lower Canada Glacier have median dissolved (<0.4 μm) concentrations of Fe, Mn, As, Cu, and V of 71.5, 75.5, 3.7, 4.6, and 4.3 nM. All dissolved Cd concentrations and the vast majority of Pb values are below our analytical detection (i.e., 0.4 and 0.06 nM). Chemical behavior did not follow similar trends for eastern and western draining waters. Heterogeneity likely reflects distinctions eolian deposition, rock:water ratios, and hydrologic connectivity. Future increases in wind-delivered sediment will likely drive dynamic responses in melt chemistry. For elements above detection limits, dissolved concentrations in glacier surface melt are within an order of magnitude of concentrations observed in proglacial streams (i.e., flowing on the valley floor). The Fe enrichment of cryoconite water relative to N, P, or Si exceeds enrichment observed in marine phytoplankton. This suggests that the glacier surface is an important source of Fe to downstream ecosystems.
VL - 6 UR - http://journal.frontiersin.org/article/10.3389/feart.2018.00031/full JO - Front. Earth Sci. ER - TY - JOUR T1 - Drivers of solar radiation variability in the McMurdo Dry Valleys, Antarctica JF - Scientific Reports Y1 - 2018 A1 - Maciek K. Obryk A1 - Andrew G Fountain A1 - Peter T. Doran A1 - W. Berry Lyons A1 - Eastman, R. AB -
Annually averaged solar radiation in the McMurdo Dry Valleys, Antarctica has varied by over 20 W m−2 during the past three decades; however, the drivers of this variability are unknown. Because small differences in radiation are important to water availability and ecosystem functioning in polar deserts, determining the causes are important to predictions of future desert processes. We examine the potential drivers of solar variability and systematically eliminate all but stratospheric sulfur dioxide. We argue that increases in stratospheric sulfur dioxide increase stratospheric aerosol optical depth and decrease solar intensity. Because of the polar location of the McMurdo Dry Valleys (77–78°S) and relatively long solar ray path through the stratosphere, terrestrial solar intensity is sensitive to small differences in stratospheric transmissivity. Important sources of sulfur dioxide include natural (wildfires and volcanic eruptions) and anthropogenic emission.
VL - 8 UR - http://www.nature.com/articles/s41598-018-23390-7.pdf JO - Sci Rep ER - TY - JOUR T1 - Fe and Nutrients in Coastal Antarctic Streams: Implications for Primary Production in the Ross Sea JF - Journal of Geophysical Research: Biogeosciences Y1 - 2018 A1 - Sydney A. Olund A1 - W. Berry Lyons A1 - Sue Welch A1 - Kathleen A. Welch AB -
The Southern Ocean (SO) has been an area of biogeochemical interest due to the presence of macronutrients (N, P, and Si) but lack of the expected primary production response, which is thought to be primarily due to Fe limitation. Because primary production is associated with increased drawdown of atmospheric CO2, it is important to quantify the fluxes of Fe and other nutrients into the SO. Here we present data from subaerial streams that flow into the Ross Sea, a sector of the coastal SO. Water samples were collected in the McMurdo Dry Valleys, Antarctica, and analyzed for macronutrients and Fe to determine the potential impact of terrestrial water input on the biogeochemistry of coastal oceanic waters. The physiochemical forms of Fe were investigated through analysis of three operationally defined forms: acid-dissolvable Fe (no filtration), filterable Fe (<0.4 μm), and dissolved Fe (<0.2 μm). The combined average flux from two McMurdo Dry Valley streams was approximately 240 moles of filterable Fe per year. The dissolved fraction of Fe made up 18%–27% of the filterable Fe. The stream data yield an average filterable stoichiometry of N3P1Si100Fe0.8, which is substantially different from the planktonic composition and suggests that these streams are a potential source of Fe and P, relative to N and Si, to coastal phytoplankton communities. While the Fe flux from these streams is orders of magnitude less than estimated eolian and iceberg sources, terrestrial streams are expected to become a more significant source of Fe to the Ross Sea in the future.
VL - 123 UR - https://agupubs.pericles-prod.literatumonline.com/doi/full/10.1029/2017JG004352 IS - 12 JO - J. Geophys. Res. Biogeosci. ER - TY - JOUR T1 - The impact of fossil fuel burning related to scientific activities in the McMurdo Dry Valleys, Antarctica: Revisited JF - Elementa: Science of the Anthropocene Y1 - 2018 A1 - W. Berry Lyons A1 - Saelens, Elsa D. A1 - Kathleen A. Welch KW - carbon dynamics KW - emissions KW - fossil fuels KW - helicopter KW - management KW - McMurdo Dry Valleys KW - nitrogen KW - science activites AB -
Fossil fuel use associated with scienti c activities in the Taylor Valley, Antarctic has been examined to determine the fluxes of particulate organic and elemental carbon and nitrogen as well as NOx for the 2015–2016 austral summer field season. These carbon and nitrogen fluxes are compared to our previously published calculations for the 1997–1998 austral summer. In addition, we compile fossil fuel usage and resulting C and N fluxes from the major field camp in Taylor Valley, Lake Hoare Camp (LHC) from the late 1990’s through 2017. In general, the annual fluxes do vary from year to year, but there is no significant trend, at least during the primary summer field season. There is indication that increasing the length of scientific operations does increase the C and N inputs via fossil fuel burning. This works supports our original results demonstrating that over long periods of time the anthropogenic flux of N from local fossil fuel burning could become quantitatively important in the region. Although the particulate C fluxes remain very low, the recent finding of black carbon in the Taylor Valley landscape indicates more on-going monitoring of the source of this material is merited.
VL - 6 UR - https://www.elementascience.org/article/10.1525/elementa.288/ JO - Elem Sci Anth ER - TY - JOUR T1 - Near-surface refractory black carbon observations in the atmosphere and snow in the McMurdo Dry Valleys, Antarctica and potential impacts of foehn winds JF - Journal of Geophysical Research: Atmospheres Y1 - 2018 A1 - Khan, Alia L. A1 - McMeeking, Gavin A1 - Schwarz, Joshua P. A1 - Xian, Peng A1 - Kathleen A. Welch A1 - W. Berry Lyons A1 - Diane M. McKnight AB -
Measurements of light absorbing particles in the boundary layer of the high southern latitudes are scarce, particularly in the McMurdo Dry Valleys (MDV), Antarctica. During the 2013 - 2014 austral summer near-surface boundary layer refractory black carbon (rBC) aerosols were measured in air by a single particle soot photometer (SP2) at multiple locations in the MDV. Near-continuous rBC atmospheric measurements were collected at Lake Hoare Camp (LH) over two months and for several hours at more remote locations away from established field camps. We investigated periods dominated by both up and down-valley winds to explore the causes of differences in rBC concentrations and size distributions. Snow samples were also collected in a 1m pit on a glacier near the camp. The range of concentrations rBC in snow were 0.3 – 1.2 ± 0.3 μg-rBC/L-H2O, and total organic carbon were 0.3 – 1.4 ± 0.3 mg/L. The rBC concentrations measured in this snow pit are not sufficient to reduce surface albedo, however, there is potential for accumulation of rBC on snow and ice surfaces at low elevation throughout the MDV which were not measured as part of this study. At LH, the average background rBC mass aerosol concentrations was 1.3 ng/m3. rBC aerosol mass concentrations were slightly lower, 0.09 – 1.3 ng/m3, at the most remote sites in the MDV. Concentration spikes as high as 200 ng/m3 were observed at LH, associated with local activities. During a foehn wind event, the average rBC mass concentration increased to 30-50 ng m-3. Here we show the rBC increase could be due to resuspension of locally produced BC from generators, rocket toilets, and helicopters, which may remain on the soil surface until redistributed during high wind events. Quantification of local production and long-range atmospheric transport of rBC to the MDV is necessary for understanding the impacts of this species on regional climate.
VL - 123 UR - http://doi.wiley.com/10.1002/2017JD027696 IS - 5 JO - J. Geophys. Res. Atmos. ER - TY - JOUR T1 - Stable C and N isotope ratios reveal soil food web structure and identify the nematode Eudorylaimus antarcticus as an omnivore–predator in Taylor Valley, Antarctica JF - Polar Biology Y1 - 2018 A1 - Shaw, E. Ashley A1 - Byron Adams A1 - John E. Barrett A1 - W. Berry Lyons A1 - Ross A. Virginia A1 - Diana H. Wall AB -
Soil food webs of the McMurdo Dry Valleys, Antarctica are simple. These include primary trophic levels of mosses, algae, cyanobacteria, bacteria, archaea, and fungi, and their protozoan and metazoan consumers (including relatively few species of nematodes, tardigrades, rotifers, and microarthropods). These biota are patchily distributed across the landscape, with greatest faunal biodiversity associated with wet soil. Understanding trophic structure is critical to studies of biotic interactions and distribution; yet, McMurdo Dry Valley soil food web structure has been inferred from limited laboratory culturing and micro- scopic observations. To address this, we measured stable isotope natural abundance ratios of C (13C/12C) and N (15N/14N) for di erent metazoan taxa (using whole body biomass) to determine soil food web structure in Taylor Valley, Antarctica. Nitrogen isotopes were most useful in di erentiating trophic levels because they fractionated predictably at higher trophic levels. Using 15N/14N, we found that three trophic levels were present in wet soil habitats. While cyanobacterial mats were the primary trophic level, the nematode Plectus murrayi, tardigrade Acutuncus antarcticus, and rotifers composed a secondary trophic level of grazers. Eudorylaimus antarcticus had a 15N/14N ratio that was 2–4‰ higher than that of grazers, indicating that this species is the sole member of a tertiary trophic level. Understanding the trophic positions of soil fauna is critical to predictions of current and future species interactions and their distributions for the McMurdo Dry Valleys, Antarctica.
VL - 41 UR - http://link.springer.com/10.1007/s00300-017-2243-8 IS - 5 JO - Polar Biol ER - TY - JOUR T1 - Transit times and rapid chemical equilibrium explain chemostasis in glacial meltwater streams in the McMurdo Dry Valleys, Antarctica JF - Geophysical Research Letters Y1 - 2018 A1 - Wlostowski, Adam A1 - Michael N. Gooseff A1 - Diane M. McKnight A1 - W. Berry Lyons AB -Fluid transit time is understood to be an important control on the shape of concentration-discharge (C-q) relationships, yet empirical evidence supporting this linkage is limited. We investigated C-q relationships for weathering-derived solutes across seven Antarctic glacial meltwate streams. We hypothesized that (H1) solute fluxes in McMurdo Dry Valley streams are reaction limited so that C-q relationships are characterized by dilution and that (H2) transit time explains between-stream variability in the degree of C-q dilution. Results show that C-q relationships are chemostatic because solute equilibrium times are shorter than stream corridor fluid transit times. Between-stream variability in the efficiency of solute production is positively correlated with transit time, suggesting that transit time is an important control on the solute export regime. These results provide empirical evidence for the controls on weathering-derived C-q relationships and have important implications for Antarctic ecosystems and solute export regimes of watersheds worldwide.
VL - 45 UR - https://agupubs.onlinelibrary.wiley.com/doi/full/10.1029/2018GL080369 IS - 24 JO - Geophys. Res. Lett. ER - TY - JOUR T1 - Ca isotopic geochemistry of an Antarctic aquatic system JF - Geophysical Research Letters Y1 - 2017 A1 - W. Berry Lyons A1 - Bullen, T A1 - Kathleen A. Welch AB -The McMurdo Dry Valleys, Antarctica, are a polar desert ecosystem. The hydrologic system of the dry valleys is linked to climate with ephemeral streams that flow from glacial melt during the austral summer. Past climate variations have strongly influenced the closed-basin, chemically stratified lakes on the valley floor. Results of previous work point to important roles for both in-stream processes (e.g., mineral weathering, precipitation and dissolution of salts) and in-lake processes (e.g., mixing with paleo-seawater and calcite precipitation) in determining the geochemistry of these lakes. These processes have a significant influence on calcium (Ca) biogeochemistry in this aquatic ecosystem, and thus variations in Ca stable isotope compositions of the waters can aid in validating the importance of these processes. We have analyzed the Ca stable isotope compositions of streams and lakes in the McMurdo Dry Valleys. The results validate the important roles of weathering of aluminosilicate minerals and/or CaCO3 in the hyporheic zone of the streams, and mixing of lake surface water with paleo-seawater and precipitation of Ca-salts during cryo-concentration events to form the deep lake waters. The lakes in the McMurdo Dry Valleys evolved following different geochemical pathways, evidenced by their unique, nonsystematic Ca isotope signatures.
VL - 44 UR - http://onlinelibrary.wiley.com/doi/10.1002/2016GL071169/full IS - 2 JO - Geophys. Res. Lett. ER - TY - THES T1 - Comparing the Weathering Environment of Permian and Modern Antarctic Proglacial Lake Sediments: Mineralogical and Geochemical Study T2 - School of Earth Sciences Y1 - 2017 A1 - Brewster, Shelby A. ED - W. Berry Lyons AB -The Antarctic continent has been in a polar to subpolar position since the Permian period. Although it has experienced milder climates over this time period as evidenced by corals in the fossil record, Antarctica did undergo extensive glaciation during the Permian. This is based on the abundance of Permian tillites (sedimentary rocks derived from glacier tills) found in the Transantarctic Mountains. In this research, I have compared Permian age proglacial lake sediments that are associated with tilites to modern proglacial lake siltstones and mudstones from Antarctica. This was done to determine the climate, especially the amount of glacier melt that occurred when these Permian sediments were deposited. The modern lake sediments are deposited in perennially ice-covered lakes by ephemeral streams that only flow 6 to 12 weeks a year. The geochemical analyses of the Permian samples and the modern sediments from Lake Hoare in the McMurdo Dry Valleys suggest that the Permian samples are more highly chemically weathered than the modern sediments. The mineralogy of Lake Hoare sediments contain more primary minerals than chemical weathering produced minerals in the Pagoda Formation rocks, thus supporting the geochemical analysis that the Pagoda Formation minerals have been more weathered. All these data suggest that the Permian lake samples were deposited in a warmer, more hydrogeologically active environment than were the modern lake sediments. These data support previously published sedimentological and paleontological data that the Pagoda samples were deposited under more temperate or warm-based proglacial conditions than what is observed in the McMurdo Dry Valleys today.
JF - School of Earth Sciences PB - The Ohio State University CY - Columbus, OH VL - B.S. UR - http://hdl.handle.net/1811/80763 ER - TY - JOUR T1 - Decadal ecosystem response to an anomalous melt season in a polar desert in Antarctica JF - Nature Ecology & Evolution Y1 - 2017 A1 - Michael N. Gooseff A1 - John E. Barrett A1 - Byron Adams A1 - Peter T. Doran A1 - Andrew G Fountain A1 - W. Berry Lyons A1 - Diane M. McKnight A1 - John C. Priscu A1 - Eric R. Sokol A1 - Cristina D. Takacs-Vesbach A1 - Martijn L. Vandegehuchte A1 - Ross A. Virginia A1 - Diana H. Wall VL - 1 UR - https://www.nature.com/articles/s41559-017-0253-0 IS - 9 JO - Nat Ecol Evol ER - TY - THES T1 - Fe and Nutrients in Coastal Antarctic Streams: Implications for Marine Primary Production in the Ross Sea T2 - Earth Sciences Y1 - 2017 A1 - Sydney A. Olund ED - W. Berry Lyons AB -The Southern Ocean (SO) has been an area of much biogeochemical interest due to the role of Fe limitation for primary production. Primary production is associated with increased carbon sequestration, making it important to characterize and quantify the fluxes of Fe and other nutrients to the ocean. Water samples were collected in the McMurdo Dry Valleys, Antarctica (MDV) from four subaerial streams flowing into the Ross Sea. They were analyzed for macronutrients (N, P, Si) and Fe to determine the potential impact of terrestrial water input on the biogeochemistry of coastal oceanic waters. Our stream data yield an average filterable composition of N3P1 Si100Fe0.8, which is substantially different from the planktonic composition as demonstrated by empirical measurements, and suggests that these streams are a potential source of Fe and P, relative to N and Si, to coastal phytoplankton communities.
Aeolian processes play an important role in the transport of both geological and biological materials globally, on the biogeochemistry of ecosystems, and in landscape evolution. As the largest ice free area on the Antarctic continent (approximately 4800 km2), the McMurdo Dry Valleys (MDV) are potentially a major source of aeolian material for Antarctica, but information on the spatial and temporal variability of this material is needed to understand its soluble and bulk geochemistry, deposition and source, and hence influence on ecosystem dynamics. 53 samples of aeolian material from Alatna Valley, Victoria Valley, Miers Valley, and Taylor Valley (Taylor Glacier, East Lake Bonney, F6 (Lake Fryxell), and Explorer’s Cove) were collected at five heights (5, 10, 20, 50, 100 cm) above the surface seasonally for 2013 through 2015. The sediment was analyzed for soluble solids, total and organic carbon, minerology, and bulk chemistry. Of the soluble component, the major anions varied between Cl- and HCO3-, and the major cation was Na+ for all sites. Soluble N:P ratios in the aeolian material reflect nutrient limitations seen in MDV soils, where younger, coastal soils are N-limited, while older, up valley soils are P-limited. Material from East Lake Bonney was P-limited in the winter samples, but N-limited in the full year samples, suggesting different sources of material based on season. Analysis of soluble salts in aeolian material in Taylor Valley compared to published soil literature demonstrates a primarily down valley transport of materials from Taylor Glacier towards the coast. The bulk chemistry suggests that the aeolian material is highly unweathered (CIA values less than 60 %), but scanning electron microscope images show alteration for some individual sediment grains. The mineralogy was reflective of local rocks, specifically the McMurdo Volcanics, Ferrar Dolerite, Beacon Sandstone and granite, but variations in major oxide percentages and rare earth element signatures could not be explained by mixing lines between these four rock types. This potentially suggests that there may be an additional, and possibly distant, source of aeolian material to the MDV that is not accounted for. This work provides the first fully elevated spatial and temporal analysis of the geochemistry of aeolian material from the Dry Valleys, and contributes to a better understanding of sediment provenance and how aeolian deposition may affect surface biological communities.
JF - Earth Sciences PB - Ohio State University VL - M.S. UR - http://rave.ohiolink.edu/etdc/view?acc_num=osu1500468216147725 ER - TY - JOUR T1 - A temporal stable isotopic (δ18O, δD, d-excess) comparison in glacier meltwater streams, Taylor Valley, Antarctica JF - Hydrological Processes Y1 - 2017 A1 - Leslie, D.L. A1 - Kathleen A. Welch A1 - W. Berry Lyons AB -In this paper, we describe the importance of hyporheic dynamics within Andersen Creek and Von Guerard Stream, Taylor Valley, Antarctica, from the 2010–2011 melt season using natural tracers. Water collection started at flow onset and continued, with weekly hyporheic‐zone sampling. The water δ18O and δD values were isotopically lighter in the beginning and heavier later in the season. D‐excess measurements were used as an indicator of mixing because an evaporative signature was evident and distinguishable between 2 primary end‐members (glacier meltwater and hyporheic zone). Hyporheic‐zone influence on the channel water was variable with a strong control on streamwater chemistry, except at highest discharges. This work supports previous research indicating that Von Guerard Stream has a large, widespread hyporheic zone that varies in size with time and discharge. Andersen Creek, with a smaller hyporheic zone, displayed hyporheic‐zone solute interaction through the influence from subsurface hypersaline flow. Overall, the evolution of Taylor Valley hyporheic‐zone hydrology is described seasonally. In mid‐December, the hyporheic zone is a dynamic system exchanging with the glacier meltwater in the channel, and with diminishing flow in January, the hyporheic zone drains back into the channel flow also impacting stream chemistry. This work adds new information on the role of hyporheic zone–stream interaction in these glacier meltwater streams.
VL - 31 UR - http://onlinelibrary.wiley.com/doi/10.1002/hyp.11245/full IS - 17 JO - Hydrological Processes ER - TY - JOUR T1 - Evidence for dispersal and habitat controls on pond diatom communities from the McMurdo Sound Region of Antarctica JF - Polar Biology Y1 - 2016 A1 - Sakaeva, A. A1 - Eric R. Sokol A1 - Tyler J. Kohler A1 - Lee F. Stanish A1 - Sarah A. Spaulding A1 - Howkins, Adrian A1 - Kathleen A. Welch A1 - W. Berry Lyons A1 - John E. Barrett A1 - Diane M. McKnight UR - http://link.springer.com/10.1007/s00300-016-1901-6http://link.springer.com/content/pdf/10.1007/s00300-016-1901-6http://link.springer.com/content/pdf/10.1007/s00300-016-1901-6.pdfhttp://link.springer.com/article/10.1007/s00300-016-1901-6/fulltext.html JO - Polar Biol ER - TY - JOUR T1 - Hydrological Controls on Ecosystem Dynamics in Lake Fryxell, Antarctica JF - PLOS ONE Y1 - 2016 A1 - Herbei, Radu A1 - Rytel, Alexander L. A1 - W. Berry Lyons A1 - Diane M. McKnight A1 - Chris Jaros A1 - Michael N. Gooseff A1 - John C. Priscu ED - Hewitt, Judi VL - 11 UR - http://dx.plos.org/10.1371/journal.pone.0159038 IS - 7 JO - PLoS ONE ER - TY - JOUR T1 - Patterns of hydrologic connectivity in the McMurdo dry valleys, Antarctica: a synthesis of 20 years of hydrologic data JF - Hydrological Processes Y1 - 2016 A1 - Wlostowski, Adam A1 - Michael N. Gooseff A1 - Diane M. McKnight A1 - Chris Jaros A1 - W. Berry Lyons AB -Streams in the McMurdo Dry Valleys (MDVs) of Antarctica moderate an important hydrologic and biogeochemical connection between upland alpine glaciers, valley-bottom soils, and lowland closed-basin lakes. Moreover, MDV streams are simple but dynamic systems ideal for studying interacting hydrologic and ecological dynamics. This work synthesizes 20 years of hydrologic data, collected as part of the MDVs Long-Term Ecological Research project, to assess spatial and temporal dynamics of hydrologic connectivity between glaciers, streams, and lakes. Long-term records of stream discharge (Q), specific electrical conductance (EC), and water temperature (T) from 18 streams were analysed in order to quantify the magnitude, duration, and frequency of hydrologic connections over daily, annual, and inter-annual timescales. At a daily timescale, we observe predictable diurnal variations in Q, EC, and T. At an annual timescale, we observe longer streams to be more intermittent, warmer, and have higher median EC values, compared to shorter streams. Longer streams also behave chemostatically with respect to EC, whereas shorter streams are more strongly characterized by dilution. Inter-annually, we observe significant variability in annual runoff volumes, likely because of climatic variability over the 20 record years considered. Hydrologic connections at all timescales are vital to stream ecosystem structure and function. This synthesis of hydrologic connectivity in the MDVs provides a useful end-member template for assessing hydrologic connectivity in more structurally complex temperate watersheds.
VL - 30 UR - http://onlinelibrary.wiley.com/doi/10.1002/hyp.10818 IS - 17 JO - Hydrol. Process. ER - TY - JOUR T1 - Stream biogeochemical and suspended sediment responses to permafrost degradation in stream banks in Taylor Valley, Antarctica JF - Biogeosciences Y1 - 2016 A1 - Michael N. Gooseff A1 - David J. Van Horn A1 - Sudman, Zachary A1 - Diane M. McKnight A1 - Kathleen A. Welch A1 - W. Berry Lyons AB -Stream channels in the McMurdo Dry Valleys are characteristically wide, incised, and stable. At typical flows, streams occupy a fraction of the oversized channels, providing habitat for algal mats. In January 2012, we discovered substantial channel erosion and subsurface thermomechanical erosion undercutting banks of the Crescent Stream. We sampled stream water along the impacted reach and compared concentrations of solutes to the long-term data from this stream ( ∼ 20 years of monitoring). Thermokarst-impacted stream water demonstrated higher electrical conductivity, and concentrations of chloride, sulfate, sodium, and nitrate than the long-term medians. These results suggest that this mode of lateral permafrost degradation may substantially impact stream solute loads and potentially fertilize stream and lake ecosystems. The potential for sediment to scour or bury stream algal mats is yet to be determined, though it may offset impacts of associated increased nutrient loads to streams.
VL - 13 UR - http://www.biogeosciences.net/13/1723/2016/bg-13-1723-2016.pdf IS - 6 JO - Biogeosciences ER - TY - JOUR T1 - Antarctic streams as a potential source of iron for the Southern Ocean: Figure 1. JF - Geology Y1 - 2015 A1 - W. Berry Lyons A1 - Dailey, Kelsey R. A1 - Kathleen A. Welch A1 - Deuerling, Kelly M. A1 - Sue Welch A1 - Diane M. McKnight AB -Due to iron’s role in oceanic primary production, there has been great interest in quantifying the importance of Fe in regions where concentrations are very low and macronutrients, nitrate and phosphate, are available. Measurements of filterable (i.e., <0.4 μm) Fe concentrations in streams from Taylor Valley, McMurdo Dry Valleys, Antarctica, suggest that coastal-zone stream Fe input to the Southern Ocean could potentially play an important role in primary production in nearshore regions. Filterable Fe (fFe) data from streams in the McMurdo Dry Valleys were used to represent glacier meltwater that flows through ice-free landscape with the potential of transporting Fe to the Antarctic coastal zone. Estimates of potential fFe flux to the Antarctic Peninsula region using our mean fFe concentration of 10.6 µg L–1 combined with an estimate of ice-free area for the Antarctic Peninsula result in an fFe flux of 1.2 × 107 g yr–1. Although small compared to iceberg and aeolian Fe fluxes, future stream input to the Southern Ocean could increase due to glacier retreat and
VL - 43 UR - http://geology.gsapubs.org/lookup/doi/10.1130/G36989.1http://geology.geoscienceworld.org/lookup/doi/10.1130/G36989.1 IS - 11 JO - Geology ER - TY - THES T1 - Chemical Weathering and Mineralogy of McMurdo Dry Valley Streams: Examining the Controls of Current and Future Ephemeral Stream Geochemistry T2 - School of Earth Sciences Y1 - 2015 A1 - Scheuermann, Jordan A1 - W. Berry Lyons AB -The McMurdo Dry Valleys form the largest ice-free region in Antarctica and are the coldest, driest deserts in the world. But, for approximately 6-12 weeks per year in the austral summer, continuous sunlight and near-freezing temperatures create meltwater streams that descend from the surrounding alpine glaciers. These ephemeral streams are a distinctive feature in the barren dry valley landscape and are important sources of nutrients and solutes from the weathering of streambed and hyporheic zone materials. This setting has been a US National Science Foundation funded Long-Term Ecological Research (LTER) project since 1993. A major goal of the McMurdo LTER is to understand how liquid water, the primary limiting condition for life in Antarctica, is affected by climate variability. The McMurdo Dry Valleys are extremely climate-sensitive and even seemingly small variations in temperature can have a drastic effect on hydrological activity. The McMurdo LTER program has been successful in collecting and analyzing a large amount of stream data pertaining to weathering products but, a more comprehensive analysis and interpretation of the data have yet to be undertaken. Assessment of current and future stream geochemistry is critical to predict the impact of increased water flow due to glacier melt and increasing temperature which could greatly influence the ecological function and biologic diversity in the McMurdo Dry Valleys. Surface sediments were collected at multiple locations from ephemeral streams and analyzed using a scanning electron microscope and x-ray diffraction to determine sediment mineralogy and evidence of chemical weathering. Geochemical reactions were modeled using previously collected stream water data and the USGS PHREEQC software for the speciation calculations and the assessment of the solubility controlling solid phases. Chemical weathering was apparent through visible mineral alteration and the formation of secondary weathering products. Modeling results indicate that stream geochemistry will not significantly be affected by increased water temperature in the future. These results suggest stream geochemistry and chemical weathering may instead be controlled primarily through hydrologic exchange in the hyporheic zone.
JF - School of Earth Sciences CY - Ohio State University VL - Undergraduate Theses UR - http://hdl.handle.net/1811/68887 ER - TY - JOUR T1 - Comparison of arsenic and molybdenum geochemistry in meromictic lakes of the McMurdo Dry Valleys, Antarctica: Implications for oxyanion-forming trace element behavior in permanently stratified lakes JF - Chemical Geology Y1 - 2015 A1 - Yang, Ningfang A1 - Kathleen A. Welch A1 - Mohajerin, T. Jade A1 - Telfeyan, Katherine A1 - Chevis, Darren A. A1 - Grimm, Deborah A. A1 - W. Berry Lyons A1 - White, Christopher D. A1 - Johannesson, Karen H. AB -Water samples were collected for arsenic (As) and molybdenum (Mo) analysis from different depths in Lakes Hoare and Fryxell, both of which are located in the Taylor Valley within the McMurdo Dry Valleys of Antarctica. Sampling depths within each lake were chosen to capture variations in As and Mo concentrations and As speciation in the oxic mixolimnia and anoxic monimolimnia of these meromictic lakes. Arsenic concentrations ranged from 0.67 nmol kg− 1 to 3.54 nmol kg− 1 in Lake Hoare and from 1.69 nmol kg− 1 to 17.5 nmol kg− 1 in Lake Fryxell. Molybdenum concentrations varied between 5.05 nmol kg− 1 and 43 nmol kg− 1 in Lake Hoare, and between 3.52 nmol kg− 1 and 25.5 nmol kg− 1 in Lake Fryxell. Concentrations of As and Mo generally increased with depth in the mixolimnion of each lake, consistent with uptake near the ice–water interface by organic particles and/or Fe/Mn oxides/oxyhydroxides, followed by gravitational settling and regeneration/remineralization at depth in the vicinity of the redoxcline. Arsenic concentrations either remained constant (Hoare) or increased with depth (Fryxell) in the anoxic monimolimnia, whereas Mo exhibited dramatic decreases in concentrations across the redoxcline in both lakes. Geochemical modeling predicts that As and Mo occur as thioanions in the anoxic bottom waters of Lakes Hoare and Fryxell, and further that the contrasting behavior of both trace elements reflects the respective reactivity of their thioanions towards Fe-sulfide minerals such as mackinawite (FeS) and/or pyrite (FeS2). More specifically, the geochemical model suggests that Fe-sulfide mineral precipitation in the anoxic monimolimnia of both lakes regulates dissolved sulfide concentrations at levels that are too low for As-sulfide minerals (e.g., orpiment, realgar) to precipitate, whereas mackinawite and/or pyrite react(s) with particle reactive thiomolybdate anions, possibly forming an Fe–Mo–S mineral that precipitates and, hence, leads to Mo removal from solution.
VL - 404 UR - http://linkinghub.elsevier.com/retrieve/pii/S0009254115001874http://api.elsevier.com/content/article/PII:S0009254115001874?httpAccept=text/xmlhttp://api.elsevier.com/content/article/PII:S0009254115001874?httpAccept=text/plain JO - Chemical Geology ER - TY - JOUR T1 - Experimental formation of pore fluids in McMurdo Dry Valleys soils JF - Antarctic Science Y1 - 2015 A1 - Joseph S. Levy A1 - Andrew G Fountain A1 - W. Berry Lyons A1 - Kathleen A. Welch AB -The 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.
VL - 27 UR - http://www.journals.cambridge.org/abstract_S0954102014000479 IS - 02 JO - Antarctic Science ER - TY - JOUR T1 - Patterns and processes of salt efflorescences in the McMurdo region, Antarctica JF - Artic, Antarctic and Alpine Research Y1 - 2015 A1 - Bisson, K. M. A1 - Kathleen A. Welch A1 - Sue Welch A1 - Sheets, J. M. A1 - W. Berry Lyons A1 - Joseph S. Levy A1 - Andrew G Fountain AB -Evaporite 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.
UR - http://aaarjournal.org/doi/abs/10.1657/AAAR0014-024 ER - TY - JOUR T1 - Potential for real-time understanding of coupled hydrologic and biogeochemical processes in stream ecosystems: Future integration of telemetered data with process models for glacial meltwater streams JF - Water Resources Research Y1 - 2015 A1 - Diane M. McKnight A1 - Cozzetto, K A1 - Cullis, James D.S. A1 - Michael N. Gooseff A1 - Chris Jaros A1 - Koch, J. A1 - W. Berry Lyons A1 - Neupauer, R. M. A1 - Wlostowski, Adam VL - 51 UR - http://doi.wiley.com/10.1002/2015WR017618http://api.wiley.com/onlinelibrary/tdm/v1/articles/10.1002%2F2015WR017618 IS - 8 JO - Water Resour. Res. ER - TY - JOUR T1 - A roadmap for Antarctic and Southern Ocean science for the next two decades and beyond JF - Antarctic Science Y1 - 2015 A1 - Kennicutt, M.C. A1 - Steven L. Chown A1 - Cassano, J.J. A1 - Liggett, D. A1 - Lloyd S. Peck A1 - Massom, R. A1 - Rintoul, S.R. A1 - Storey, J. A1 - Vaughan, D.G. A1 - Wilson, T.J. A1 - Allison, I. A1 - Ayton, J. A1 - Badhe, R. A1 - Baeseman, J. A1 - Barrett, P.J. A1 - Elanor R. Bell A1 - Bertler, N. A1 - Bo, S. A1 - Brandt, A. A1 - David Bromwich A1 - Craig S Cary A1 - Clark, M.S. A1 - Peter Convey A1 - Costa, E.S. A1 - Cowan, D. A1 - Deconto, R. A1 - Dunbar, R. A1 - Elfring, C. A1 - Escutia, C. A1 - Francis, J. A1 - Fricker, H.A. A1 - Fukuchi, M. A1 - Gilbert, N. A1 - Gutt, J. A1 - Havermans, C. A1 - Hik, D. A1 - Hosie, G. A1 - Jones, C. A1 - Kim, Y.D. A1 - Le Maho, Y. A1 - Lee, S.H. A1 - Leppe, M. A1 - Leitchenkov, G. A1 - Li, X. A1 - Lipenkov, V. A1 - Lochte, K. A1 - López-Martínez, J. A1 - üdecke, C. A1 - W. Berry Lyons A1 - Marenssi, S. A1 - Miller, H. A1 - Morozova, P. A1 - Naish, T. A1 - Nayak, S. A1 - Ravindra, R. A1 - Retamales, J. A1 - Ricci, C.A. A1 - Rogan-Finnemore, M. A1 - Ropert-Coudert, Y. A1 - Samah, A.A. A1 - Sanson, L. A1 - Scambos, T. A1 - I.R. Schloss A1 - Shiraishi, K. A1 - Siegert, M.J. A1 - Simões, J.C. A1 - Storey, B. A1 - Sparrow, M.D. A1 - Diana H. Wall A1 - Walsh, J.C. A1 - Wilson, G. A1 - Winther, J.G. A1 - J.C. Xavier A1 - Yang, H. A1 - Sutherland, W.J. AB -Antarctic and Southern Ocean science is vital to understanding natural variability, the processes that govern global change and the role of humans in the Earth and climate system. The potential for new knowledge to be gained from future Antarctic science is substantial. Therefore, the international Antarctic community came together to ‘scan the horizon’ to identify the highest priority scientific questions that researchers should aspire to answer in the next two decades and beyond. Wide consultation was a fundamental principle for the development of a collective, international view of the most important future directions in Antarctic science. From the many possibilities, the horizon scan identified 80 key scientific questions through structured debate, discussion, revision and voting. Questions were clustered into seven topics: i) Antarctic atmosphere and global connections, ii) Southern Ocean and sea ice in a warming world, iii) ice sheet and sea level, iv) the dynamic Earth, v) life on the precipice, vi) near-Earth space and beyond, and vii) human presence in Antarctica. Answering the questions identified by the horizon scan will require innovative experimental designs, novel applications of technology, invention of next-generation field and laboratory approaches, and expanded observing systems and networks. Unbiased, non-contaminating procedures will be required to retrieve the requisite air, biota, sediment, rock, ice and water samples. Sustained year-round access to Antarctica and the Southern Ocean will be essential to increase winter-time measurements. Improved models are needed that represent Antarctica and the Southern Ocean in the Earth System, and provide predictions at spatial and temporal resolutions useful for decision making. A co-ordinated portfolio of cross-disciplinary science, based on new models of international collaboration, will be essential as no scientist, programme or nation can realize these aspirations alone
VL - 27 UR - http://www.journals.cambridge.org/abstract_S0954102014000674 IS - 01 JO - Antarctic Science ER - TY - JOUR T1 - Boron isotopic geochemistry of the McMurdo Dry Valley lakes, Antarctica JF - Chemical Geology Y1 - 2014 A1 - Leslie, D.L. A1 - W. Berry Lyons A1 - Warner, Nathaniel A1 - Vengosh, Avner A1 - Olesik, J A1 - Kathleen A. Welch A1 - Deuerling, Kelly AB -
The geochemistry of boron was investigated in the ice-covered lakes and glacier meltwater streams within Taylor and Wright Valley of the McMurdo Dry Valleys (MCM), Antarctica, in order to achieve a greater understanding of the source of boron to these aquatic systems and how in-lake processes control boron concentration. Selected lake depths (surface and bottom water) and streams were analyzed for boron geochemistry. Boron stable isotope values in these waters span the range of + 12.3‰ to + 51.4‰, which corresponds to the variations from glacier meltwater streams to the hypolimnion of a highly evaporated hypersaline lake. The data demonstrate that the major sources of B to the aquatic system are via terrestrial chemical weathering of aluminosilicates within the stream channels, and a marine source, either currently being introduced by marine-derived aerosols or in the form of ancient seawater. Lakes Fryxell, Hoare, and upper waters of Lake Joyce, which experience more terrestrial influence of aluminosilicate chemical weathering via glacial meltwater streams, display a mixture of these two major sources, while the source of B in the bottom waters of Lake Joyce appears to be primarily of marine origin. Lakes Bonney and Vanda and the Blood Falls brine have a marine-like source whose δ11B values have become more positive by mineral precipitation and/or adsorption. Don Juan Pond displays a terrestrial aluminosilicate influence of a marine-like source. These hypersaline lake waters from Antarctica are similar in δ11B to other hypersaline lake waters globally, suggesting that similar processes control their B geochemistry.
VL - 386 UR - http://linkinghub.elsevier.com/retrieve/pii/S000925411400391Xhttp://api.elsevier.com/content/article/PII:S000925411400391X?httpAccept=text/xmlhttp://api.elsevier.com/content/article/PII:S000925411400391X?httpAccept=text/plain JO - Chemical Geology ER - TY - JOUR T1 - The effects of high meltwater on the limnology of Lake Fryxell and Lake Hoare, Taylor Valley, Antarctica, as shown by dissolved gas, tritium and chlorofluorocarbons JF - Antarctic Science Y1 - 2014 A1 - Carolyn Dowling A1 - Robert J. Poreda A1 - W. Berry Lyons AB -
Small changes in the availability of liquid water can have profound effects on the water levels, aqueous chemistry and biogeochemical dynamics of the closed-basin, perennially ice-covered lakes of the McMurdo Dry Valleys, Antarctica. We have compiled the published and unpublished data on dissolved gas, tritium and chlorofluorocarbons (CFCs) for Lake Fryxell and Lake Hoare to determine the effects of a high meltwater year (2001–02 summer) on the lakes. The dissolved gas, tritium and CFC data indicate that the pulse of freshwater that flowed onto the surfaces of the lakes did not mix extensively with the upper water column. At the bottom of Lake Hoare, the measurable CFC and lower dissolved gas values suggest that the recent meltwater may have mixed with bottom waters. The probable mechanism for this transportation is weak density currents with c. 0.1–1.5% surface water being transported downwards in Lake Hoare. This deep water input, while not constant, may have a significant effect on the chemistry of the bottom waters in Lake Hoare over time. In Lake Fryxell, the tritium and CFC data indicate that the recent meltwater did not significantly affect the bottom water chemistry; therefore, weak density currents may not be present in Lake Fryxell.
VL - 26 UR - http://www.journals.cambridge.org/abstract_S095410201300062X IS - 04 JO - Antarctic Science ER - TY - THES T1 - Elemental Cycling in a Flow-Through Lake in the McMurdo Dry Valleys, Antarctica: Lake Miers T2 - Earth Sciences Y1 - 2014 A1 - Alexandria Corinne Fair A1 - W. Berry Lyons ED - Anne E. Carey ED - Yu-Ping Chin AB -The ice-free area in Antarctica known as the McMurdo Dry Valleys has been monitored biologically, meteorologically, hydrologically, and geochemically continuously since the onset of the MCM-LTER in 1993. This area contains a functioning ecosystem living in an extremely delicate environment. Only a few degrees of difference in air temperature can effect on the hydrologic system, making it a prime area to study ongoing climate change. The unique hydrology of Lake Miers, i.e. its flowthrough nature, makes it an ideal candidate to study the mass balance of a McMurdo Dry Valley lake because both input and output concentrations can be analyzed. This study seeks to understand the physical and geochemical hydrology of Lake Miers relative to other MCMDV lakes. Samples were collected from the two inflowing streams, the outflowing stream, and the lake itself at 11 depths to analyze a suite of major cations (Li+ , Na+ , K+ , Mg+ , Ca2+), major anions (Cl- , Br- , F- , SO4 2- , ΣCO2), nutrients (NO2 - , NO3 - , NH4 + , PO4 3- , Si), trace elements (Mo, Rb, Sr, Ba, U, V, Cu, As), water isotopes (δD, δ 18O), and dissolved organic carbon (DOC). The lake acts as a sink for all constituents analyzed, but by amounts varying from ~10% (DOC, NH4 + , and NO2 - ) to PO4 3- at nearly 100%, indicating this lake may be P-limited. Cl- , a typically conservative element, was only 79% retained, which could be due to the late season sample collection, hyperheic zone influences, or other factors. The hyperheic zone’s role in lake and stream iii geochemistry was analyzed with a 24-hour sampling event. The positive relationships between stream flow and solute concentrations indicate that the delta in Miers Valley plays a role in controlling stream geochemistry and future work could help to explain this relationship. Lake depth profiles of trace elements U, V, Cu, and As decrease relative to Cl in the deepest part of the lake, while non-reducing trace elements show increases with depth. SO4 2- and dissolved O2 lake depth profiles decrease from 53 μM and 22.3 mg/L to 18 μM and 1.8 mg/L, respectively, at depth, indicating that the lake bottom is under reducing and near anoxic conditions. Lake depth profiles show that, while the “biological pump” may be a factor controlling lake chemistry, it is masked by the stronger signal of diffusion from the lake bottom sediments and requires future work to understand fully. The “age” of Lake Miers was calculated with a diffusion model to be 84 years, which agrees with other estimates of 100-300 years. The diffusion of solutes from the lake bottom and the redox conditions at depth are two major processes controlling the geochemistry of Lake Miers, and future work can help determine their extent and relationship with other processes.
JF - Earth Sciences PB - Ohio State University CY - Columbus VL - Master Thesis UR - https://etd.ohiolink.edu/!etd.send_file?accession=osu1413291502&disposition=inline ER - TY - JOUR T1 - Radiocarbon abundance and reservoir effects in lakes of the McMurdo Dry Valleys, Antarctica JF - Limnology and Oceanography Y1 - 2014 A1 - Peter T. Doran A1 - Kenig, Fabien A1 - Lawson Knoepfle A1 - Jill A. Mikucki A1 - W. Berry Lyons VL - 59 IS - 3 ER - TY - JOUR T1 - The spatial structure of Antarctic biodiversity JF - Ecological Monographs Y1 - 2014 A1 - Peter Convey A1 - Steven L. Chown A1 - Clarke, Andrew A1 - Barnes, David K. A. A1 - Bokhorst, Stef A1 - Vonda Cummings A1 - Hugh W. Ducklow A1 - Francesco Frati A1 - Green, T. G. Allan A1 - Shulamit Gordon A1 - Griffiths, Huw J. A1 - Clive Howard-Williams A1 - Huiskes, Ad H. L. A1 - Johanna Laybourn-Parry A1 - W. Berry Lyons A1 - McMinn, Andrew A1 - Morley, Simon A. A1 - Lloyd S. Peck A1 - Quesada, Antonio A1 - Robinson, Sharon A. A1 - Schiaparelli, Stefano A1 - Diana H. Wall AB -Patterns of environmental spatial structure lie at the heart of the most fundamental and familiar patterns of diversity on Earth. Antarctica contains some of the strongest environmental gradients on the planet and therefore provides an ideal study ground to test hypotheses on the relevance of environmental variability for biodiversity. To answer the pivotal question, “How does spatial variation in physical and biological environmental properties across the Antarctic drive biodiversity?” we have synthesized current knowledge on environmental variability across terrestrial, freshwater, and marine Antarctic biomes and related this to the observed biotic patterns. The most important physical driver of Antarctic terrestrial communities is the availability of liquid water, itself driven by solar irradiance intensity. Patterns of biota distribution are further strongly influenced by the historical development of any given location or region, and by geographical barriers. In freshwater ecosystems, free water is also crucial, with further important influences from salinity, nutrient availability, oxygenation, and characteristics of ice cover and extent. In the marine biome there does not appear to be one major driving force, with the exception of the oceanographic boundary of the Polar Front. At smaller spatial scales, ice cover, ice scour, and salinity gradients are clearly important determinants of diversity at habitat and community level. Stochastic and extreme events remain an important driving force in all environments, particularly in the context of local extinction and colonization or recolonization, as well as that of temporal environmental variability. Our synthesis demonstrates that the Antarctic continent and surrounding oceans provide an ideal study ground to develop new biogeographical models, including life history and physiological traits, and to address questions regarding biological responses to environmental variability and change.
My dissertation research utilizes stable isotopes as tracers of water and solute sources to study specific geochemical (solute origin) and hydrological (glacier meltwater source across a season comparing water contributions from hyporheic zone and/or glacier melt and residence time of precipitation within a managed water supply) problems within McMurdo Dry Valleys (MCM), Antarctica, and Central Ohio, USA. In Chapter II, δ11B isotopic and dissolved B measurements are used to infer the origin of B within MCM aquatic system. Boron stable isotopic values span the range of +12.3‰ to +51.4‰, varying from glacier meltwater streams to the hypolimnion of a highly evaporated hypersaline lake. These data demonstrate that the major sources of B are chemical weathering of alumniosilicates within the stream channels, and a marine source, either currently introduced by marine-derived aerosols or from ancient seawater. In-lake processes create a more positive δ11B through adsorption or mineral precipitation. The glacier meltwater streams, Lakes Fryxell, Hoare, and upper waters of Lake Joyce display a mixture of these two sources, with Lake Joyce bottom waters primarily of marine origin. Lakes Bonney and Vanda and Blood Falls brine are interpreted as having a marine-like source changed by in-lake processes to result in a more positive δ11B, while Don Juan Pond displays a more terrestrial influence. In Chapter III, δ18O and δD are used to trace water source variation via hyporheic zone or glacier melt within two MCM streams over an entire melt season. The isotopic variation of these streams was more negative at the beginning of the season and more positive later. D-excess measurements were used to infer mixing between hyporheic storage and glacier meltwater. It was supported that Von Guerard Stream has a large, widespread hyporheic zone that changes with time and discharge amounts. The chemistry of Andersen Creek also displayed hyporheic zone influence at certain times of the year. This work adds important new information on the role of hyperheic zone-stream interactions, and supports the short term, more physically based, descriptions of hyporheic dynamics explained in the past decade. Chapter IV describes water flow and travel time within a human managed watershed-reservoir system by measuring the δ18O and δD of the precipitation source to the reservoirs and finally to the distribution system, the tap. Generally, the tap waters experienced little lag time in the managed system, having a residence time of about two months. Tap and reservoir waters preserved the precipitation signal with the reservoir morphology acting as an important control. These water supply reservoirs functioned more like a river system with a faster throughput of water and larger variations in chemical parameters. Other water supply reservoirs have a greater capacity with a larger amount of water supply usage through a more lacustrine environment, which displays more constant solute concentrations and longer flow-through times. This work provides a basic understanding of a regional water supply system in central Ohio, reservoir isotopic dynamics, and Ohio precipitation sources.
JF - Geological Sciences PB - Ohio State University CY - Columbus, OH VL - Ph.D. UR - http://rave.ohiolink.edu/etdc/view?acc_num=osu1386000037 ER - TY - JOUR T1 - The carbon stable isotope biogeochemistry of streams, Taylor Valley, Antarctica JF - Applied Geochemistry Y1 - 2013 A1 - W. Berry Lyons A1 - Leslie, D.L. A1 - Harmon, R.S. A1 - Klaus Neumann A1 - Kathleen A. Welch A1 - Bisson, K. M. A1 - Diane M. McKnight VL - 32 ER - TY - JOUR T1 - Do Cryoconite Holes have the Potential to be Significant Sources of C, N, and P to Downstream Depauperate Ecosystems of Taylor Valley, Antarctica? JF - Arctic, Antarctic, and Alpine Research Y1 - 2013 A1 - Bagshaw, Elizabeth A1 - Martyn Tranter A1 - Andrew G Fountain A1 - Kathleen A. Welch A1 - Hassan J. Basagic A1 - W. Berry Lyons VL - 45 IS - 4 ER - TY - JOUR T1 - Garwood Valley, Antarctica: A new record of Last Glacial Maximum to Holocene glaciofluvial processes in the McMurdo Dry Valleys JF - Geological Society of America Bulletin Y1 - 2013 A1 - Joseph S. Levy A1 - Andrew G Fountain A1 - O'Connor, J. E. A1 - Kathleen A. Welch A1 - W. Berry Lyons VL - 125 UR - http://bulletin.geoscienceworld.org/content/early/2013/06/07/B30783.1.abstract IS - 9-10 ER - TY - JOUR T1 - Understanding Terrestrial Ecosystem Response to Antarctic Climate Change JF - Eos, Transactions American Geophysical Union Y1 - 2013 A1 - Joseph S. Levy A1 - W. Berry Lyons A1 - Byron Adams VL - 94 UR - http://onlinelibrary.wiley.com/doi/10.1002/2013EO030009/abstract IS - 3 ER - TY - JOUR T1 - Water track modification of soil ecosystems in the Lake Hoare basin, Taylor Valley, Antarctica JF - Antarctic Science Y1 - 2013 A1 - Joseph S. Levy A1 - Andrew G Fountain A1 - Michael N. Gooseff A1 - John E. Barrett A1 - Robert Vantreese A1 - Kathleen A. Welch A1 - W. Berry Lyons A1 - Uffe N. Nielsen A1 - Diana H. Wall ER - TY - JOUR T1 - The geochemistry of upland ponds, Taylor Valley, Antarctica JF - Antarctic Science Y1 - 2012 A1 - W. Berry Lyons A1 - Kathleen A. Welch A1 - Christopher B. Gardner A1 - Chris Jaros A1 - Daryl L. Moorhead A1 - Knoepfle, J A1 - Peter T. Doran VL - 24 UR - http://journals.cambridge.org/action/displayAbstract?fromPage=online&aid=8483351 IS - 01 ER - TY - JOUR T1 - Hypersaline “wet patches” in Taylor Valley, Antarctica JF - Geophysical Research Letters Y1 - 2012 A1 - Joseph S. Levy A1 - Andrew G Fountain A1 - Kathleen A. Welch A1 - W. Berry Lyons VL - 39 IS - 5 ER - TY - JOUR T1 - Perchlorate and chlorate biogeochemistry in ice-covered lakes of the McMurdo Dry Valleys, Antarctica JF - Geochimica et Cosmochimica Acta Y1 - 2012 A1 - W. Andrew Jackson A1 - Alfonso F. Davila A1 - Nubia Estrada A1 - W. Berry Lyons A1 - John D. Coates A1 - John C. Priscu VL - 98 UR - http://www.sciencedirect.com/science/article/pii/S001670371200511X ER - TY - ICOMM T1 - Taylor’s ‘missing’ lake: Integrating history into LTER research in the McMurdo Dry Valley Y1 - 2012 A1 - Khan, A A1 - Howkins, Adrian A1 - W. Berry Lyons PB - LTER News CY - Albuquerque VL - 2013 UR - http://news.lternet.edu/Article2568.html ER - TY - JOUR T1 - Hydrological Connectivity of the Landscape of the McMurdo Dry Valleys, Antarctica JF - Geography Compass Y1 - 2011 A1 - Michael N. Gooseff A1 - Diane M. McKnight A1 - Peter T. Doran A1 - Andrew G Fountain A1 - W. Berry Lyons VL - 5 UR - http://onlinelibrary.wiley.com/doi/10.1111/j.1749-8198.2011.00445.x IS - 9 ER - TY - JOUR T1 - Long-term ecosystem networks to record change: an international imperative JF - Antarctic Science Y1 - 2011 A1 - Diana H. Wall A1 - W. Berry Lyons A1 - Steven L. Chown A1 - Peter Convey A1 - Clive Howard-Williams A1 - Quesada, Antonio A1 - Warwick F. Vincent VL - 23 UR - http://www.journals.cambridge.org/abstract_S0954102011000319 IS - 03 JO - Antarctic Science ER - TY - JOUR T1 - Water tracks and permafrost in Taylor Valley, Antarctica: Extensive and shallow groundwater connectivity in a cold desert ecosystem JF - Geological Society of America Bulletin Y1 - 2011 A1 - Joseph S. Levy A1 - Andrew G Fountain A1 - Michael N. Gooseff A1 - Kathleen A. Welch A1 - W. Berry Lyons VL - 123 UR - http://bulletin.geoscienceworld.org/content/123/11-12/2295.short IS - 11-12 ER - TY - THES T1 - Aeolian sediments of the McMurdo Dry Valleys, Antarctica T2 - Geological Sciences Y1 - 2010 A1 - Deuerling, Kelly M. A1 - W. Berry Lyons KW - aeolian transport KW - Antarctica KW - dust KW - experimental leaching KW - geochemistry KW - McMurdo Dry Valleys KW - sediment provenance KW - weathering AB -The role of dust has become a topic of increasing interest in the interface between climate and geological/ecological sciences. Dust emitted from major sources, the majority of which are desert regions in the Northern Hemisphere, is transported via suspension in global wind systems and incorporated into the biogeochemical cycles of the ecosystems where it is ultimately deposited. While emissions within the McMurdo Dry Valleys (MDV) region of Antarctica are small compared to other source regions, the redistribution of new, reactive material by wind may be important to sustaining life in the ecosystem.
The interaction of the dry, warm foehn winds and the cool, moist coastal breezes “recycles” soil particles throughout the landscape. The bulk of sediment movement occurs during foehn events in the winter that redistribute material throughout the MDV. To understand the source and transfer of this material samples were collected early in the austral summer (November 2008) prior to the initiation of extensive ice melt from glacial and lake surfaces, aeolian landforms, and elevated sediment traps. These were preserved and processed for grain size distribution and major element composition at the sand and silt particle sizes. Major elemental oxide analysis indicated that the silt and sand size particles are of different composition: SiO2 values for silt range from 50 to 59% by weight and for sand range from 59 to 74%. When compared to the elemental oxide composition four rock types present in the MDV, the composition of the silt indicates a mixing influenced mostly by the igneous rock types (Ferrar Dolerite and McMurdo Volcanic basanite) and sand a mixing influenced largely by the sedimentary rocks (Beacon Sandstone and the metasedimentary Basement Complex). This could imply a local source of the aeolian material that is corroborated by low CIA values at both particle sizes (44-57%) indicating low degrees of chemical weathering. In addition, comparison of 87Sr/86Sr and 143Nd/144Nd to values published for the major MDV rock types and ice core dust to values analyzed in 3 silt size glacier sample and one bulk glacier sample also indicates a local source of sediments and that it is not likely to be transferred inland.
During the melt season, the aeolian material is actively solubilized where it interacts with water, releasing solutes and vital bioavailable nutrients throughout the aquatic system. Differences in the chemistry of supra- and proglacial streams as well as lake surface waters may be derived from the deposition and dissolution of these aeolian sediments. To simulate these conditions, a two-step leaching method using deionized water to represent glacial melt in field conditions was employed and leachates analyzed for major ion and nutrient constituents. Leachates represent a small degree (<0.7%) of dissolution of major elements, and are solubilized to a greater extent from samples closer to the coast or with increased silt content. The composition of the leachates reflects the dissolution of the major salts found in the MDV. Leach 1 (cold water) indicates that Na- and Cl-bearing salt phases are dissolved to a greater extent than seen in Leach 2 (freeze-thaw). Conversely, Leach 2 compositions indicate that carbonate mineral dissolution and Mg-bearing silicate weathering are proceeding to a greater extent than in Leach 1.
Inorganic N:P ratios follow the same patterns of nutrient limitations based on the Redfield Ratio found by Priscu (1995) in the terminal lakes of the Taylor Valley: N-limited in the Fryxell and Hoare basins (east) and P-limited in the Bonney basin (west). This is also consistent with the age of the tills in the area, as found by Gudding (2003). The concentration of soluble Fe in the leachates is about the same as soluble inorganic P, and thus is not a limiting nutrient in the leachates. Comparison of total dissolved N and P to their inorganic counterparts reveals increased organic nutrients in the glacier and lake leachates that may indicate the influence of biota. Nutrient fluxes based on known sediment fluxes from elevated sediment traps deployed throughout the MDV and the composition of these leachates range from 0.34-330 g a-1 for N, 0.02-8.3 g a-1 for P, and 0.03-8.6 g a-1 for Fe. These are at least two orders of magnitude less than calculated loads from streams to the lakes in the Taylor Valley and, thus, should be considered underestimations or minima.
This work provides the first investigation into the composition and source of aeolian transported materials in the MDV, as well of what is potentially solubilized from it during the austral summer melt season. In addition, it will contribute to the understanding of the interplay between aeolian and aquatic processes in the MDV and further the understanding of this unique ecosystem.
Among aquatic and terrestrial landscapes of the McMurdo Dry Valleys, Antarctica, ecosystem stoichiometry ranges from values near the Redfield ratios for C:N:P to nutrient concentrations in proportions far above or below ratios necessary to support balanced microbial growth. This polar desert provides an opportunity to evaluate stoichiometric approaches to understand nutrient cycling in an ecosystem where biological diversity and activity are low, and controls over the movement and mass balances of nutrients operate over 10–106 years. The simple organisms (microbial and metazoan) comprising dry valley foodwebs adhere to strict biochemical requirements in the composition of their biomass, and when activated by availability of liquid water, they influence the chemical composition of their environment according to these ratios. Nitrogen and phosphorus varied significantly in terrestrial and aquatic ecosystems occurring on landscape surfaces across a wide range of exposure ages, indicating strong influences of landscape development and geochemistry on nutrient availability. Biota control the elemental ratio of stream waters, while geochemical stoichiometry (e.g., weathering, atmospheric deposition) evidently limits the distribution of soil invertebrates. We present a conceptual model describing transformations across dry valley landscapes facilitated by exchanges of liquid water and biotic processing of dissolved nutrients. We conclude that contemporary ecosystem stoichiometry of Antarctic Dry Valley soils, glaciers, streams, and lakes results from a combination of extant biological processes superimposed on a legacy of landscape processes and previous climates.
VL - 112 ER - TY - JOUR T1 - Organic carbon in Antarctic precipitation JF - Geophysical Research Letters Y1 - 2007 A1 - W. Berry Lyons A1 - Kathleen A. Welch A1 - Doggett, J VL - 34 ER - TY - JOUR T1 - Reactivation of a cryptobiotic stream ecosystem in the McMurdo Dry Valleys, Antarctica: A long-term geomorphological experiment JF - Geomorphology Y1 - 2007 A1 - Diane M. McKnight A1 - Cathy M. Tate A1 - Edmund D. Andrews A1 - Dev K. Niyogi A1 - Cozzetto, K A1 - Kathleen A. Welch A1 - W. Berry Lyons A1 - D. G. Capone VL - 89 IS - 1-2 ER - TY - JOUR T1 - Solute and isotope geochemistry of subsurface ice melt seeps in Taylor Valley, Antarctica JF - Geological Society of America Bulletin Y1 - 2007 A1 - Harris, K A1 - Anne E. Carey A1 - Kathleen A. Welch A1 - W. Berry Lyons A1 - Andrew G Fountain KW - Climate Response VL - 119 UR - http://gsabulletin.gsapubs.org/content/119/5-6/548.short IS - 5-6 ER - TY - Generic T1 - Trends in discharge and flow season timing of the Onyx River, Wright Valley, Antarctica since 1969 T2 - Antarctica; A keystone in a changing world--online proceedings for the tenth international symposium Y1 - 2007 A1 - Michael N. Gooseff A1 - Diane M. McKnight A1 - Peter T. Doran A1 - W. Berry Lyons ED - Alan Cooper ED - Carol Raymond ED - ISAES Editorial Team JF - Antarctica; A keystone in a changing world--online proceedings for the tenth international symposium PB - U.S. Geological Survey Open-File Report 2007-1047 ER - TY - JOUR T1 - The aeolian flux of calcium, chloride and nitrate to the McMurdo Dry Valleys landscape: Evidence from snow pit analysis JF - Antarctic Science Y1 - 2006 A1 - Witherow, R A1 - Bertler, N A1 - Kathleen A. Welch A1 - W. Berry Lyons A1 - Paul A. Mayewski A1 - Sneed, S A1 - Thomas H. Nylen A1 - Handley, M A1 - Andrew G Fountain VL - 18 ER - TY - CHAP T1 - Antarctic lake systems and climate change T2 - Trends in Antarctic Terrestrial and Limnetic Ecosystems: Antarctica as a Global Indicator Y1 - 2006 A1 - W. Berry Lyons A1 - Johanna Laybourn-Parry A1 - Kathleen A. Welch A1 - John C. Priscu ED - D.M. Bergstrom ED - Peter Convey ED - A.H.L. Huiskes JF - Trends in Antarctic Terrestrial and Limnetic Ecosystems: Antarctica as a Global Indicator PB - S CY - Dordrecht, The Netherlands ER - TY - JOUR T1 - Measuring ecosystem response in a rapidly changing environment: the Latitudinal Gradient Project JF - Antarctic Science. Y1 - 2006 A1 - Clive Howard-Williams A1 - Peterson, D A1 - W. Berry Lyons A1 - Cattaneo-Vietti, R A1 - Shulamit Gordon VL - 10 IS - 4 ER - TY - CHAP T1 - Pedogenic carbonate distribution within glacial till in Taylor Valley, Southern Victoria Land, Antarctica T2 - Paleoenvironmental Record and Applications of Calcretes and Palustrine Carbonates Y1 - 2006 A1 - Foley, K A1 - W. Berry Lyons A1 - John E. Barrett A1 - Ross A. Virginia JF - Paleoenvironmental Record and Applications of Calcretes and Palustrine Carbonates PB - Geological Society of America ER - TY - THES T1 - A Qualitative Approach to Understanding the Rate of Weathering, Taylor Valley, Antarctica Y1 - 2006 A1 - Miller, E PB - The Ohio State University ER - TY - JOUR T1 - A stable isotopic investigation of a polar desert hydrologic system, McMurdo Dry Valleys, Antarctica JF - Arctic, Antarctic, and Alpine Research Y1 - 2006 A1 - Michael N. Gooseff A1 - W. Berry Lyons A1 - Diane M. McKnight A1 - Bruce H. Vaughn A1 - Andrew G Fountain A1 - Carolyn Dowling VL - 38 IS - 1 ER - TY - JOUR T1 - Terrestrial ecosystem processes of Victoria Land, Antarctica JF - Soil Biology and Biochemistry Y1 - 2006 A1 - John E. Barrett A1 - Johnson N. Nkem A1 - Sletten, R A1 - Steltzer, H A1 - Diana H. Wall A1 - Wallenstein, M A1 - Ross A. Virginia A1 - D. W. Hopkins A1 - Aislabie, J A1 - Bargagli, R A1 - Bockheim, J A1 - Campbell, I A1 - W. Berry Lyons A1 - Daryl L. Moorhead VL - 38 ER - TY - JOUR T1 - The chemical composition of runoff from Canada Glacier, Antarctica: implications for glacier hydrology during a cool summer JF - Annals of Glaciology Y1 - 2005 A1 - Martyn Tranter A1 - Andrew G Fountain A1 - W. Berry Lyons A1 - Thomas H. Nylen A1 - Kathleen A. Welch VL - 40 ER - TY - JOUR T1 - Comment on ``El Niño suppresses Antarctic warming'' by N. Bertler et al. JF - Geophysical Research Letters Y1 - 2005 A1 - Peter T. Doran A1 - Gary D. Clow A1 - Christian H. Fritsen A1 - Christopher P. McKay A1 - Andrew N. Parsons A1 - John C. Priscu A1 - W. Berry Lyons A1 - Walsh, J A1 - Andrew G Fountain A1 - Diane M. McKnight A1 - Daryl L. Moorhead A1 - Ross A. Virginia A1 - Diana H. Wall KW - Tropical meteorology VL - 32 IS - 7 ER - TY - JOUR T1 - Dating water and solute additions to ice-covered Antarctic lakes JF - Geochimica et Cosmochimica Acta Y1 - 2005 A1 - W. Berry Lyons A1 - Carolyn Dowling A1 - Kathleen A. Welch A1 - Snyder, G A1 - Robert J. Poreda A1 - Peter T. Doran A1 - Andrew G Fountain VL - 69 ER - TY - JOUR T1 - The Geochemistry of Supraglacial Streams of Canada Glacier, Taylor Valley (Antarctica), and their Evolution into Proglacial Waters JF - Aquatic Geochemistry Y1 - 2005 A1 - Sarah Fortner A1 - Martyn Tranter A1 - Andrew G Fountain A1 - W. Berry Lyons A1 - Kathleen A. Welch VL - 11 ER - TY - JOUR T1 - Groundwater seeps in Taylor Valley Antarctica: An example of a subsurface melt event JF - Annals of Glaciology Y1 - 2005 A1 - W. Berry Lyons A1 - Kathleen A. Welch A1 - Anne E. Carey A1 - Diana H. Wall A1 - Ross A. Virginia A1 - Andrew G Fountain A1 - Peter T. Doran A1 - Csatho, B A1 - Tremper, C VL - 40 ER - TY - JOUR T1 - Halogen geochemistry of the McMurdo Dry Valleys Lakes, Antarctica: clues to the origin of solutes and lake evolution JF - Geochimica et Cosmochimica Acta Y1 - 2005 A1 - W. Berry Lyons A1 - Kathleen A. Welch A1 - Snyder, G A1 - Olesik, J A1 - Graham, E A1 - G. M. Marion A1 - Robert J. Poreda VL - 69 ER - TY - THES T1 - Mathematical Modeling of a Hydrocarbon Spill on the Ice Cover of Lake Fryxell, Antarctica T2 - Geological Sciences Y1 - 2005 A1 - Marinko Karnovic A1 - Anne E. Carey A1 - Scott E. Bair A1 - van der Veen, Cornelis AB -Numerous perennially ice-covered lakes exist in the McMurdo Dry Valleys region of Antarctica. Ice cover melting on these lakes and meltwater infiltration are important processes affecting the ecology of these lakes. The three lakes in Taylor Valley, Lakes Bonney, Fryxell and Hoare, have been investigated since 1993 as part of the McMurdo Dry Valleys Long Term Ecological Research (MCM LTER) site. A Bell 212 helicopter flying in support of the National Science Foundation's Antarctic Research Program crashed on the frozen surface of Lake Fryxell on January 17, 2003. This resulted in the release of approximately 731 Liters (193 gallons) of diesel fuel and amounts of engine oil and hydraulic fluid. Two physically based models are developed that simulate heat, meltwater flow and solute transport. The first is a transient, one-dimensional, thermodynamic model, which can predict the temperature distribution in the ice cover, melting rate at the surface and at the bottom of ice cover, and ice thickness. The second model simulates unsaturated flow and solute transport and is used to estimate water content distribution and solute transport through the ice cover. The validation of heat transport model was accomplished by comparing model results with the original measurements of ice temperature at various depth in Lake Fryxell. Because of lack of the field data, validation of the unsaturated flow and solute transport model couldn't been accomplished, instead of model validation, programming code has been verified by comparing results with results generated by the HYDRUS 1D software, developed by U.S. Salinity Laboratory, USDA.
JF - Geological Sciences PB - The Ohio State University CY - Columbus VL - M.S. ER - TY - THES T1 - Mercury Concentrations in Snow and the Modern Mercury Flux to Taylor Valley, Antarctica Y1 - 2005 A1 - Witherow, R PB - The Ohio State University VL - M.S. ER - TY - THES T1 - Pedogenic Carbonate Distribution within Glacial Till in Taylor Valley, Southern Victoria Land, Antarctica Y1 - 2005 A1 - Foley, K PB - The Ohio State University VL - M.S. ER - TY - JOUR T1 - Perturbation of hydrochemical conditions in natural microcosms entombed within Antarctic ice JF - Ice and Climate News Y1 - 2005 A1 - Martyn Tranter A1 - Andrew G Fountain A1 - Christian H. Fritsen A1 - W. Berry Lyons A1 - John C. Priscu A1 - Stratham, P A1 - Kathleen A. Welch VL - 6 ER - TY - JOUR T1 - The Carbon Isotopic Composition of Dissolved Inorganic Carbon in Perennially Ice-Covered Antarctica Lakes: Searching for a Biogenic Signature. JF - Annals of Glaciology Y1 - 2004 A1 - Klaus Neumann A1 - W. Berry Lyons A1 - John C. Priscu A1 - David J. DesMarais A1 - Kathleen A. Welch VL - 39 ER - TY - JOUR T1 - The distribution of microplankton in the McMurdo dry valley lakes, Antarctica: Response to ecosystem legacy or present-day climate controls? JF - Polar Biology Y1 - 2004 A1 - Emily C. Roberts A1 - John C. Priscu A1 - Craig F. Wolf A1 - W. Berry Lyons A1 - Johanna Laybourn-Parry VL - 27 ER - TY - JOUR T1 - Extreme hydrochemical conditions in natural microcosms entombed within Antarctic ice. JF - Hydrological Processes Y1 - 2004 A1 - Martyn Tranter A1 - Andrew G Fountain A1 - Christian H. Fritsen A1 - W. Berry Lyons A1 - John C. Priscu A1 - Stathan, P A1 - Kathleen A. Welch VL - 18 ER - TY - JOUR T1 - Geomicrobiology of Blood Fall: An iron-rich saline discharge at the terminus of the Taylor Glacier, Antarctica JF - Aquatic Geochemistry Y1 - 2004 A1 - Jill A. Mikucki A1 - Christine M. Foreman A1 - Sattler, B A1 - W. Berry Lyons A1 - John C. Priscu VL - 10 ER - TY - CHAP T1 - Paleolimnology of extreme cold terrestrial and extraterrestrial environments. T2 - Long-Term Environmental Change in Arctic and Antarctic Lakes Y1 - 2004 A1 - Peter T. Doran A1 - John C. Priscu A1 - W. Berry Lyons A1 - Powell, R A1 - Robert J. Poreda A1 - Dale T. Andersen JF - Long-Term Environmental Change in Arctic and Antarctic Lakes PB - Kluwer Academic Publishers CY - Dordrecht, The Netherlands SN - 978-1-4020-2125-1 ER - TY - CHAP T1 - Paleolimnology of Ice-covered Environments T2 - Long-term environmental change in Arctic and Antarctic lakes Y1 - 2004 A1 - Peter T. Doran A1 - John C. Priscu A1 - W. Berry Lyons A1 - Powell, R A1 - Robert J. Poreda ED - Pienitz, R ED - Douglas, Marianne S. V. ED - John Smol JF - Long-term environmental change in Arctic and Antarctic lakes PB - Kluwer Academic Publishers ER - TY - JOUR T1 - Biochemistry of Si in the McMurdo Dry Valley lakes, Antarctica JF - The International Journal of Astrobiology Y1 - 2003 A1 - Pugh, H A1 - Kathleen A. Welch A1 - W. Berry Lyons A1 - John C. Priscu A1 - Diane M. McKnight VL - 1 ER - TY - CHAP T1 - Century to millennial scale climate change and ecosystem response in Taylor Valley, Antarctica T2 - Climate Variability and Ecosystem Response at Long-Term Ecological Research Sites Y1 - 2003 A1 - Andrew G Fountain A1 - W. Berry Lyons ED - D. Greenland ED - D. G. Goodin ED - R. C. Smith KW - Climate Response JF - Climate Variability and Ecosystem Response at Long-Term Ecological Research Sites T3 - Long-Term Ecological Research Network PB - Oxford University Press CY - New York City SN - 0195150597 ER - TY - CHAP T1 - Chemistry and lake dynamics of the Taylor Valley lakes, Antarctica: The importance of long-term monitoring. T2 - Antarctic Ecosystems: Models for Wider Ecological Understanding Y1 - 2003 A1 - Kathleen A. Welch A1 - Klaus Neumann A1 - W. Berry Lyons A1 - Diane M. McKnight ED - Clive Howard-Williams ED - W. Davidson ED - P. Broady JF - Antarctic Ecosystems: Models for Wider Ecological Understanding PB - Caxton Press ER - TY - THES T1 - Phosphorus in Taylor Valley, Antarctica: the connection between landscape age and nutrient limitation in aquatic ecosystem components Y1 - 2003 A1 - Gudding, J PB - The Ohio State University VL - M.S. ER - TY - JOUR T1 - Strontium isotopic signatures of the streams and lakes of Taylor Valley, southern Victoria Land, Antarctica: chemical weathering in a polar climate JF - Aquatic Geochemistry Y1 - 2003 A1 - W. Berry Lyons A1 - C. A. Nezat A1 - Benson, L A1 - Bullen, T A1 - Graham, E A1 - Kidd, J A1 - Kathleen A. Welch A1 - Thomas, J VL - 8 ER - TY - JOUR T1 - Surface glaciochemistry of Taylor Valley, southern Victoria Land, Antarctica and its relationship to stream chemistry. JF - Hydrological Processes Y1 - 2003 A1 - W. Berry Lyons A1 - Kathleen A. Welch A1 - Andrew G Fountain A1 - Gayle L. Dana A1 - Bruce H. Vaughn A1 - Diane M. McKnight VL - 17 ER - TY - JOUR T1 - Antarctic climate cooling and terrestrial ecosystem response JF - Nature Y1 - 2002 A1 - Peter T. Doran A1 - John C. Priscu A1 - W. Berry Lyons A1 - John E. Walsh A1 - Andrew G Fountain A1 - Diane M. McKnight A1 - Daryl L. Moorhead A1 - Ross A. Virginia A1 - Diana H. Wall A1 - Gary D. Clow A1 - Christian H. Fritsen A1 - Christopher P. McKay A1 - Andrew N. Parsons KW - Climate Response VL - 415 IS - 6871 ER - TY - THES T1 - The biogeochemistry of Si in the McMurdo Dry Valley Lakes Y1 - 2002 A1 - Pugh, H PB - The Ohio State University VL - B.S. ER - TY - THES T1 - The chemical evolution of Canada Glacier melt: supraglacial and proglacial waters in Taylor Valley, Antarctica Y1 - 2002 A1 - Tegt, S PB - The Ohio State University VL - M.S. ER - TY - JOUR T1 - Recent Temperature Trends in the Antarctic JF - Nature Y1 - 2002 A1 - John E. Walsh A1 - Gary D. Clow A1 - Christian H. Fritsen A1 - Christopher P. McKay A1 - Andrew N. Parsons A1 - Peter T. Doran A1 - John C. Priscu A1 - W. Berry Lyons A1 - Andrew G Fountain A1 - Diane M. McKnight A1 - Daryl L. Moorhead A1 - Ross A. Virginia A1 - Diana H. Wall VL - 418 ER - TY - JOUR T1 - Snow patch influence on soil biogeochemical processes and invertebrate distribution in the McMurdo Dry Valleys, Antarctica JF - Arctic, Antarctic, and Alpine Research Y1 - 2002 A1 - Michael N. Gooseff A1 - John E. Barrett A1 - Peter T. Doran A1 - Andrew G Fountain A1 - W. Berry Lyons A1 - Andrew N. Parsons A1 - Porazinska, D A1 - Ross A. Virginia A1 - Diana H. Wall KW - Biggie VL - 35 UR - http://instaar.metapress.com/content/r086455ju7213711/ IS - 1 ER - TY - JOUR T1 - Valley floor climate observations from the McMurdo Dry Valleys, Antarctica, 1986-2000 JF - Journal of Geophysical Research Y1 - 2002 A1 - Peter T. Doran A1 - Christopher P. McKay A1 - Gary D. Clow A1 - Gayle L. Dana A1 - Andrew G Fountain A1 - Thomas H. Nylen A1 - W. Berry Lyons KW - Biggie AB -Climate observations from the McMurdo dry valleys, East Antarctica are presented from a network of seven valley floor automatic meteorological stations during the period 1986 to 2000. Mean annual temperatures ranged from −14.8°C to −30.0°C, depending on the site and period of measurement. Mean annual relative humidity is generally highest near the coast. Mean annual wind speed increases with proximity to the polar plateau. Site-to-site variation in mean annual solar flux and PAR is due to exposure of each station and changes over time are likely related to changes in cloudiness. During the nonsummer months, strong katabatic winds are frequent at some sites and infrequent at others, creating large variation in mean annual temperature owing to the warming effect of the winds. Katabatic wind exposure appears to be controlled to a large degree by the presence of colder air in the region that collects at low points and keeps the warm less dense katabatic flow from the ground. The strong influence of katabatic winds makes prediction of relative mean annual temperature based on geographical position (elevation and distance from the coast) alone, not possible. During the summer months, onshore winds dominate and warm as they progress through the valleys creating a strong linear relationship (r2 = 0.992) of increasing potential temperature with distance from the coast (0.09°C km−1). In contrast to mean annual temperature, summer temperature lends itself quite well to model predictions, and is used to construct a statistical model for predicting summer dry valley temperatures at unmonitored sites.
VL - 107 IS - 4772 ER - TY - JOUR T1 - Weathering reactions and hyporheic exchange controls on stream water chemistry in a glacial meltwater stream in the McMurdo Dry Valleys JF - Water Resources Research Y1 - 2002 A1 - Michael N. Gooseff A1 - Diane M. McKnight A1 - W. Berry Lyons A1 - Blum, A KW - Biggie VL - 38 UR - http://www.agu.org/pubs/crossref/2002/2001WR000834.shtml IS - 12 ER - TY - JOUR T1 - Chemical weathering in streams of a polar desert (Taylor Valley, Antarctica). JF - GSA Bulletin Y1 - 2001 A1 - C. A. Nezat A1 - W. Berry Lyons A1 - Kathleen A. Welch VL - 113 ER - TY - JOUR T1 - CO2 concentrations in perennially ice-covered lakes of Taylor Valley, Antarctica JF - Biogeochemistry Y1 - 2001 A1 - Klaus Neumann A1 - W. Berry Lyons A1 - John C. Priscu A1 - Donahoe, R VL - 56 ER - TY - JOUR T1 - The McMurdo Dry Valleys Long-Term Ecological Research Program: new understanding of the biogeochemistry of the Dry Valley lakes: a review. JF - Polar Geography Y1 - 2001 A1 - W. Berry Lyons A1 - Kathleen A. Welch A1 - John C. Priscu A1 - Johanna Laybourn-Parry A1 - Daryl L. Moorhead A1 - Diane M. McKnight A1 - Peter T. Doran A1 - Martyn Tranter VL - 25 ER - TY - CHAP T1 - Climate and hydrologic variations and implications for lake and stream ecological response in the McMurdo Dry Valleys, Antarctica T2 - Climate Variability and Ecosystem Response at Long Term Ecological Research Sites Y1 - 2000 A1 - Kathleen A. Welch A1 - W. Berry Lyons A1 - Diane M. McKnight A1 - Chris Jaros A1 - Andrew G Fountain A1 - Thomas H. Nylen A1 - Peter T. Doran A1 - Clive Howard-Williams ED - D. Greenland ED - D. G. Goodin ED - R. C. Smith JF - Climate Variability and Ecosystem Response at Long Term Ecological Research Sites PB - Oxford University Press ER - TY - JOUR T1 - Fossil fuel burning in Taylor Valley, southern Victoria Land, Antarctica: estimating the role of scientific activities on carbon and nitrogen reservoirs and fluxes JF - Environmental Science and Technology Y1 - 2000 A1 - W. Berry Lyons A1 - C. A. Nezat A1 - Kathleen A. Welch A1 - Kottmeier, S A1 - Peter T. Doran VL - 34 ER - TY - JOUR T1 - The importance of landscape position and legacy: The evolution of the Taylor Valley Lake District, Antarctica. JF - Freshwater Biology Y1 - 2000 A1 - W. Berry Lyons A1 - Andrew G Fountain A1 - Peter T. Doran A1 - John C. Priscu A1 - Klaus Neumann A1 - Kathleen A. Welch VL - 43 ER - TY - THES T1 - Carbon dynamics in lakes and streams of Taylor Valley, Antarctica Y1 - 1999 A1 - Klaus Neumann PB - University of Alabama, Tuscaloosa VL - Ph.D. ER - TY - JOUR T1 - Chlorine-36 in the waters of the McMurdo Dry Valley lakes, southern Victoria Land, Antarctica: revisited JF - Geochimica et Cosmochimica Acta Y1 - 1999 A1 - W. Berry Lyons A1 - Kathleen A. Welch A1 - Pankaj Sharma VL - 62 IS - 2 ER - TY - JOUR T1 - Dating quaternary lacustrine sediments in the McMurdo Dry Valleys Antarctica JF - Palaeography, Palaeoclimatology, Palaeoecology Y1 - 1999 A1 - Peter T. Doran A1 - G. W. Berger A1 - W. Berry Lyons A1 - Robert A. Wharton Jr. A1 - M. L. Davisson A1 - J. Southon A1 - J. E. Dibb KW - sediments VL - 147 IS - 3 ER - TY - JOUR T1 - Geomicrobiology of sub-glacial ice above Vostok Station JF - Science Y1 - 1999 A1 - John C. Priscu A1 - Edward E. Adams A1 - W. Berry Lyons A1 - Mary A. Voytek A1 - David W. Mogk A1 - Robert L. Brown A1 - Christopher P. McKay A1 - Cristina D. Takacs-Vesbach A1 - Kathleen A. Welch A1 - Craig F. Wolf A1 - Julie D. Kirshtein A1 - Recep Avci VL - 286 IS - 5447 ER - TY - JOUR T1 - History of McMurdo Dry Valley Lakes, Antarctica, from stable chlorine isotope data JF - Geology Y1 - 1999 A1 - W. Berry Lyons A1 - Frape, S A1 - Kathleen A. Welch VL - 27 IS - 527-530 ER - TY - JOUR T1 - Mercury in aquatic systems in Antarctica JF - Geophysical Research Letters Y1 - 1999 A1 - W. Berry Lyons A1 - Kathleen A. Welch A1 - Jean-Claude Bonzongo VL - 26 IS - 15 ER - TY - JOUR T1 - Physical controls on the Taylor Valley Ecosystem, Antarctica JF - BioScience Y1 - 1999 A1 - Andrew G Fountain A1 - W. Berry Lyons A1 - Melody B. Burkins A1 - Gayle L. Dana A1 - Peter T. Doran A1 - Karen J. Lewis A1 - Diane M. McKnight A1 - Daryl L. Moorhead A1 - Andrew N. Parsons A1 - John C. Priscu A1 - Diana H. Wall A1 - Robert A. Wharton Jr. A1 - Ross A. Virginia KW - Water availability VL - 49 IS - 12 ER - TY - THES T1 - Chemical Weathering in Taylor Valley, Antarctica: Quantity and Quality Y1 - 1998 A1 - C. A. Nezat PB - University of Alabama, Tuscaloosa VL - Ph.D. ER - TY - JOUR T1 - Evidence of deep circulation in two perennially ice-covered Antarctic lakes JF - Limnol. Oceanogr. Y1 - 1998 A1 - Scott W. Tyler A1 - Peter G. Cook A1 - Anya Z. Butt A1 - James M. Thomas A1 - Peter T. Doran A1 - W. Berry Lyons VL - 43 IS - 4 ER - TY - CHAP T1 - Geochemical Linkages Among Glaciers, Streams, and Lakes Within the Taylor Valley, Antarctica T2 - Ecosystem Processes in a Polar Desert: The McMurdo Dry Valleys, Antarctica Y1 - 1998 A1 - W. Berry Lyons A1 - Kathleen A. Welch A1 - Klaus Neumann A1 - Jeffrey K. Toxey A1 - Robyn McArthur A1 - Changela Williams A1 - Diane M. McKnight A1 - Daryl L. Moorhead JF - Ecosystem Processes in a Polar Desert: The McMurdo Dry Valleys, Antarctica VL - 72 ER - TY - JOUR T1 - Inorganic carbon-isotope distribution and budget in the Lake Hoare and Lake Fryxell basins, Taylor Valley, Antarctica JF - Annals of Glaciology Y1 - 1998 A1 - Klaus Neumann A1 - W. Berry Lyons A1 - D.J. Des Marais VL - 27 ER - TY - JOUR T1 - A late holocene dessication of Lake Hoare and Lake Fryxell, McMurdo Dry Valleys, Antarctica JF - Antarctic Science Y1 - 1998 A1 - W. Berry Lyons A1 - Scott W. Tyler A1 - Robert A. Wharton Jr. A1 - Diane M. McKnight A1 - Bruce H. Vaughn VL - 10 IS - 3 ER - TY - JOUR T1 - McMurdo Dry Valleys LTER: Density-driven mixing in Lake Hoare? JF - Antarctic Journal of the United States - 1996 Review Issue (NSF 98-28) Y1 - 1998 A1 - W. Berry Lyons A1 - Kathleen A. Welch A1 - Scott W. Tyler A1 - Pankaj Sharma VL - 31 IS - 2 ER - TY - CHAP T1 - The abundance of planktonic virus-like particles in Antarctic lakes T2 - Ecosystem Processes in Antarctic Ice-free Landscapes Y1 - 1997 A1 - Kepner, R.L. A1 - Robert A. Wharton Jr. A1 - Galchenko, V JF - Ecosystem Processes in Antarctic Ice-free Landscapes PB - Balkema Press CY - Rotterdam ER - TY - CHAP T1 - Carbon dynamics of aquatic microbial mats in the Antarctic dry valleys: A modelling synthesis T2 - Ecosystem Processes in Antarctic Ice-free Landscapes Y1 - 1997 A1 - Daryl L. Moorhead A1 - W. Shane Davis A1 - Robert A. Wharton Jr. JF - Ecosystem Processes in Antarctic Ice-free Landscapes PB - Balkema Press, Rotterdam ER - TY - CHAP T1 - Chemical weathering rates and reactions in the Lake Fryxell Basin, Taylor Valley : Comparison to temperate river basins T2 - Ecosystem Processes in Antarctic Ice-free Landscapes Y1 - 1997 A1 - W. Berry Lyons A1 - Kathleen A. Welch A1 - C. A. Nezat A1 - K. Crick A1 - Jeffrey K. Toxey A1 - J.A. Mastrine A1 - Diane M. McKnight JF - Ecosystem Processes in Antarctic Ice-free Landscapes PB - Balkema Press, Rotterdam ER - TY - CHAP T1 - Climate history of the McMurdo Dry Valleys since the last glacial maximum: A synthesis T2 - Ecosystem Processes in Antarctic Ice-free Landscapes Y1 - 1997 A1 - W. Berry Lyons A1 - Louis R. Bartek A1 - Paul A. Mayewski A1 - Peter T. Doran JF - Ecosystem Processes in Antarctic Ice-free Landscapes PB - Balkema Press, Rotterdam ER - TY - CHAP T1 - Determination of rare earth elements in Antarctic lakes and streams of varying ionic strengths T2 - Plasma Source Mass Spectrometry: Developments and Applications Y1 - 1997 A1 - Graham, E A1 - Ramsey, L. A. A1 - W. Berry Lyons A1 - Kathleen A. Welch JF - Plasma Source Mass Spectrometry: Developments and Applications PB - Royal Society of Chemistry CY - London ER - TY - JOUR T1 - Lithium in waters of a polar desert JF - Geochimica et Cosmochimica Acta Y1 - 1997 A1 - W. Berry Lyons A1 - Kathleen A. Welch VL - 61 IS - 20 ER - TY - CHAP T1 - The microbial loop in Antarctic lakes T2 - Ecosystem Processes in Antarctic Ice-free Landscapes Y1 - 1997 A1 - Johanna Laybourn-Parry JF - Ecosystem Processes in Antarctic Ice-free Landscapes PB - Balkema Press CY - Rotterdam ER - TY - CHAP T1 - Sources and sinks of nutrients in a polar desert stream, the Onyx River, Antarctica T2 - Ecosystem Processes in Antarctic Ice-free Landscapes Y1 - 1997 A1 - Clive Howard-Williams A1 - Ian Hawes A1 - Anne-Maree Schwarz A1 - Julie A. Hall JF - Ecosystem Processes in Antarctic Ice-free Landscapes PB - Balkema Press CY - Rotterdam ER - TY - CHAP T1 - Species composition and primary production of algal communities in Dry Valley streams in Antarctica: Examination of the functional role of biodiversity T2 - Ecosystem Processes in Antarctic Ice-free Landscapes Y1 - 1997 A1 - Dev K. Niyogi A1 - Cathy M. Tate A1 - Diane M. McKnight A1 - John H. Duff A1 - Alexander S. Alger JF - Ecosystem Processes in Antarctic Ice-free Landscapes PB - Balkema Press, Rotterdam ER - TY - JOUR T1 - Determination of major element chemistry in terrestrial waters from Antarctica by ion chromatography JF - Journal of Chromatography A Y1 - 1996 A1 - Kathleen A. Welch A1 - W. Berry Lyons A1 - Graham, E A1 - Klaus Neumann A1 - James M. Thomas A1 - D. Mikesell VL - 739 ER - TY - JOUR T1 - McMurdo LTER: Comparative limnology of the Taylor Valley lakes: The major solutes JF - Antarctic Journal of the U.S. Y1 - 1995 A1 - Kathleen A. Welch A1 - W. Berry Lyons VL - 30 IS - 5 ER - TY - JOUR T1 - McMurdo LTER: Inorganic geochemical studies with special reference to calcium carbonate dynamics JF - Antarctic Journal of the U.S. Y1 - 1994 A1 - Kathleen A. Welch A1 - W. Berry Lyons A1 - John C. Priscu A1 - R. L. Edwards A1 - Diane M. McKnight A1 - Harold R. House A1 - Robert A. Wharton Jr. VL - 29 IS - 5 ER - TY - JOUR T1 - Paleolimnology of the McMurdo Dry Valleys, Antarctica JF - Journal of Paleolimnology Y1 - 1994 A1 - Peter T. Doran A1 - Robert A. Wharton Jr. A1 - W. Berry Lyons VL - 10 IS - 2 ER - TY - JOUR T1 - The geochemical evolution of terrestrial waters in the antarctic: the role of rock-water interactions, in Physical and Biogeochemical Processes in Antarctic Lakes Y1 - 1993 A1 - W. Berry Lyons A1 - Paul A. Mayewski VL - 59 ER - TY - JOUR T1 - Stable isotopic biogeochemistry of carbon and nitrogen in a perennially ice-covered Antarctic lake JF - Chemical Geology Y1 - 1993 A1 - Robert A. Wharton Jr. A1 - W. Berry Lyons A1 - D.J. Des Marais VL - 107 ER -