@article {4940, title = {McMurdo Dry Valley lake edge {\textquoteleft}moats{\textquoteright}: The ecological intersection between terrestrial and aquatic polar desert habitat}, journal = {Antarctic Science}, year = {2024}, month = {04/2024}, pages = {1 - 17}, abstract = {

Aquatic ecosystems - lakes, ponds and streams - are hotspots of biodiversity in the cold and arid environment of Continental Antarctica. Environmental change is expected to increasingly alter Antarctic aquatic ecosystems and modify the physical characteristics and interactions within the habitats that they support. Here, we describe physical and biological features of the peripheral \‘moat\’ of a closed-basin Antarctic lake. These moats mediate connectivity amongst streams, lake and soils. We highlight the cyclical moat transition from a frozen winter state to an active open-water summer system, through refreeze as winter returns. Summer melting begins at the lakebed, initially creating an ice-constrained lens of liquid water in November, which swiftly progresses upwards, creating open water in December. Conversely, freezing progresses slowly from the water surface downwards, with water at 1 m bottom depth remaining liquid until May. Moats support productive, diverse benthic communities that are taxonomically distinct from those under the adjacent permanent lake ice. We show how ion ratios suggest that summer exchange occurs amongst moats, streams, soils and sub-ice lake water, perhaps facilitated by within-moat density-driven convection. Moats occupy a small but dynamic area of lake habitat, are disproportionately affected by recent lake-level rises and may thus be particularly vulnerable to hydrological change.

}, keywords = {LTER-MCM, connectivity, ecosystem, ice, microbial mats, transition}, issn = {0954-1020}, doi = {10.1017/S0954102024000087}, url = {https://www.cambridge.org/core/journals/antarctic-science/article/mcmurdo-dry-valley-lake-edge-moats-the-ecological-intersection-between-terrestrial-and-aquatic-polar-desert-habitats/31D94DD51E651603482A3AE6E8A52A57}, author = {Stone, Michael S. and Devlin, Shawn and Ian Hawes and Kathleen A. Welch and Michael N. Gooseff and Cristina D. Takacs-Vesbach and Rachael M. Morgan-Kiss and Byron Adams and John E. Barrett and John C. Priscu and Peter T. Doran} } @article {4845, title = {Spatial patterns of major ions and their relationship to sediment concentration in near surface glacier ice, Taylor Valley Antarctica}, journal = {Journal of Geophysical Research: Earth Surface}, year = {2023}, month = {03/2024}, abstract = {

Glaciers form the headwaters of many watersheds and, in arid polar environments, can provide the vast majority of water to downstream systems. Headwater watersheds are critically important for setting the chemistry for downstream systems, yet we know comparatively little about the patterns and processes that generate the geochemical signature of meltwater on glacier surfaces. Here, we focus on glaciers in the McMurdo Dry Valleys of Antarctica, the largest ice-free area on the continent, characterized by alpine glaciers flowing into broad, rocky valleys. We examine patterns from the coast inland, accumulation to ablation zones, laterally across individual glaciers, and through the zone of meltwater generation. We directly compare solute to sediment concentrations, a major source of dissolved solutes. Our findings agree with previous work that the overall meltwater chemistry of a given glacier is a product local sediment sources and of regional wind patterns: foehn winds moving from the ice sheet to the coast and on-shore sea breezes. Further, these patterns hold across an individual glacier. Finally, we find that the ice chemistry and sediment profiles reflect freeze-thaw and melt processes that occur at depth. This indicates that the transport and weathering of sediment in the ice profile likely has a strong influence on supra- and proglacial stream chemistry. This new understanding strengthens connections between physical and geochemical processes in cold-based polar glacier environments and helps us better understand the processes driving landscape and ecosystem connectivity.

}, keywords = {LTER-MCM}, issn = {2169-9003}, doi = {10.1029/2022JF006980}, url = {https://onlinelibrary.wiley.com/doi/10.1029/2022JF006980}, author = {Bergstrom, Anna J. and Kathleen A. Welch and Michael N. Gooseff} } @article {4586, title = {Diatoms in hyporheic sediments trace organic matter retention and processing in the McMurdo Dry Valleys, Antarctica}, journal = {Journal of Geophysical Research: Biogeosciences}, volume = {126}, year = {2021}, month = {02/2021}, pages = {e2020JG006097}, abstract = {

In low-nutrient streams in cold and arid ecosystems, the spiraling of autochthonous particulate organic matter (POM) may provide important nutrient subsidies downstream. Because of its lability and the spatial heterogeneity of processing in hyporheic sediments, the downstream transport and fate of autochthonous POM can be difficult to trace. In Antarctic McMurdo Dry Valley (MDV) streams, any POM retained in the hyporheic zone is expected to be derived from surface microbial mats that contain diatoms with long-lasting silica frustules. We tested whether diatom frustules can be used to trace the retention of autochthonous POM in the hyporheic zone and whether certain geomorphic locations promote this process. The accumulation of diatom frustules in hyporheic sediments, measured as biogenic silica, was correlated with loss-on-ignition organic matter and sorbed ammonium, suggesting that diatoms can be used to identify locations where POM has been retained and processed over long timescales, regardless of whether the POM remains intact. In addition, by modeling the upstream sources of hyporheic diatom assemblages, we found that POM was predominantly derived from N-fixing microbial mats of the genus Nostoc. In terms of spatial variability, we conclude that the hyporheic sediments adjacent to the stream channel that are regularly inundated by daily flood pulses are where the most POM has been retained over long timescales. Autochthonous POM is retained in hyporheic zones of low-nutrient streams beyond the MDVs, and we suggest that biogenic silica and diatom composition can be used to identify locations where this transfer is most prevalent.

}, keywords = {LTER-MCM, benthic processes, biogenic silica, biogeochemical cycles processes and modeling, carbon cycling, diatoms, groundwater/surface water interactions, hyporheic zone, McMurdo Dry Valleys, nitrogen cycling, particulate organic matter}, doi = {10.1029/2020JG006097}, url = {https://agupubs.onlinelibrary.wiley.com/doi/10.1029/2020JG006097}, author = {Heindel, Ruth C and Darling, Joshua P. and Singley, Joel G. and Bergstrom, Anna J. and Diane M. McKnight and Lukkari, Braeden M. and Kathleen A. Welch and Michael N. Gooseff} } @article {4577, title = {Geochemistry of contrasting stream types, Taylor Valley, Antarctica}, journal = {GSA Bulletin}, volume = {133}, year = {2021}, month = {01/2021}, pages = {425-448}, abstract = {

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.

}, keywords = {LTER-MCM}, doi = {10.1130/B35479.1}, url = {https://pubs.geoscienceworld.org/gsa/gsabulletin/article/133/1-2/425/587799/Geochemistry-of-contrasting-stream-types-Taylor}, author = {Harmon, Russell S. and Leslie, Deborah L. and W. Berry Lyons and Kathleen A. Welch and Diane M. McKnight} } @article {4471, title = {Geochemistry of aeolian material from the McMurdo Dry Valleys, Antarctica: Insights into Southern Hemisphere dust sources}, journal = {Earth and Planetary Science Letters}, volume = {547}, year = {2020}, month = {10/2020}, abstract = {

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.

}, keywords = {LTER-MCM, aeolian material, Antarctica, major oxides, mineralogy, rare earth elements, trace elements}, doi = {10.1016/j.epsl.2020.116460}, url = {https://www.sciencedirect.com/science/article/pii/S0012821X20304040}, author = {Melisa A. Diaz and Welch, Susan A. and Sheets, J. M. and Kathleen A. Welch and Khan, Alia L. and Byron Adams and Diane M. McKnight and Craig S Cary and W. Berry Lyons} } @article {4489, title = {Nutrient uptake in the supraglacial stream network of an Antarctic glacier}, journal = {Journal of Geophysical Research: Biogeosciences}, year = {2020}, month = {08/2020}, abstract = {

In polar regions, where many glaciers are cold-based (frozen to their beds), biological communities on the glacier surface can modulate and transform nutrients, controlling downstream delivery. However, it remains unclear whether supraglacial streams are nutrient sinks or sources and the rates of nutrient processing. In order to test this, we conducted tracer-injections in three supraglacial streams (62 to 123 m long) on Canada Glacier in the Taylor Valley, of the McMurdo Dry Valleys, Antarctica. We conducted a series of additions including: nitrate (N), N + phosphate (P), N+ P + glucose (C), and N+C. In two reaches, N-only additions resulted in N uptake. The third reach showed net N release during the N-only addition, but high N uptake in the N+P addition, indicating P-limitation or N+P co-limitation. Co-injecting C did not increase N-uptake. Additionally, in these systems at low N concentrations the streams can be a net source of nitrogen. We confirmed these findings using laboratory-based nutrient incubation experiments on sediment collected from stream channels on Canada Glacier and two other glaciers in the Taylor Valley. Together, these results suggest there is active biological processing of nutrients occurring in these supraglacial streams despite low sediment cover, high flow velocities and cold temperatures, modifying the input signals to proglacial streams. As glaciers world-wide undergo rapid change, these findings further our understanding of how melt generated on glacier surfaces set the initial nutrient signature for subglacial and downstream environments.

}, keywords = {LTER-MCM, McMurdo Dry Valleys, nitrogen, nutrient tracers, nutrient uptake, sediments, supraglacial streams}, doi = {10.1029/2020JG005679}, url = {https://agupubs.onlinelibrary.wiley.com/doi/abs/10.1029/2020JG005679}, author = {Bergstrom, Anna J. and Michael N. Gooseff and Singley, Joel G. and Cohen, Matthew J. and Kathleen A. Welch} } @article {4244, title = {Diurnal chemistry of two contrasting stream types, Taylor Valley, McMurdo Dry Valley Region, Antarctica}, journal = {E3S Web of Conferences}, volume = {98}, year = {2019}, month = {06/2019}, abstract = {

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.

}, keywords = {LTER-MCM}, doi = {10.1051/e3sconf/20199801020}, url = {https://www.e3s-conferences.org/articles/e3sconf/abs/2019/24/e3sconf_wri-162018_01020/e3sconf_wri-162018_01020.html}, author = {Harmon, Mark E. and Leslie, D.L. and W. Berry Lyons and Kathleen A. Welch and Diane M. McKnight}, editor = {Chudaev, O. and Kharaka, Y. and Harmon, R.S. and Millot, R. and Shouakar-Stash, O.} } @article {4450, title = {The Geochemistry of Englacial Brine From Taylor Glacier, Antarctica}, journal = {Journal of Geophysical Research: Biogeosciences}, volume = {124}, year = {2019}, month = {03/2019}, abstract = {

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.

}, keywords = {LTER-MCM}, doi = {10.1029/2018JG004411}, url = {https://agupubs.onlinelibrary.wiley.com/doi/abs/10.1029/2018JG004411}, author = {W. Berry Lyons and Jill A. Mikucki and German, Laura A. and Kathleen A. Welch and Sue Welch and Christopher B. Gardner and Tulaczyk, Slawek M. and Pettit, Erin C. and Kowalski, Julia and Dachwald, Bernd} } @article {4373, title = {The hydroecology of an ephemeral wetland in the McMurdo Dry Valleys, Antarctica}, journal = {Journal of Geophysical Research: Biogeosciences}, year = {2019}, month = {11/2019}, abstract = {

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.

}, keywords = {LTER-MCM, Antarctica, desert hydrology, diatom biodiversity, hyporheic interactions, wetlands}, doi = {10.1029/2019JG005153}, url = {https://agupubs.onlinelibrary.wiley.com/doi/abs/10.1029/2019JG005153}, author = {Wlostowski, Adam and Schulte, Nicholas O. and Byron Adams and Ball, Becky and Rhea M.M. Esposito and Michael N. Gooseff and W. Berry Lyons and Uffe N. Nielsen and Ross A. Virginia and Diana H. Wall and Kathleen A. Welch and Diane M. McKnight} } @article {4156, title = {Aeolian material transport and its role in landscape connectivity in the McMurdo Dry Valleys, Antarctica}, journal = {Journal of Geophysical Research: Earth Surface}, volume = {123}, year = {2018}, month = {12/2018}, pages = {3323 - 3337}, abstract = {

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.

}, keywords = {LTER-MCM}, doi = {10.1029/2017JF004589}, url = {https://agupubs.onlinelibrary.wiley.com/doi/full/10.1029/2017JF004589}, author = {Melisa A. Diaz and Byron Adams and Kathleen A. Welch and Sue Welch and Opiyo, Stephen O. and Khan, Alia L. and Diane M. McKnight and Craig S Cary and W. Berry Lyons} } @article {4138, title = {Barium and barite dynamics in Antarctic streams}, journal = {Geology}, volume = {46}, year = {2018}, month = {08/2018}, pages = {811 - 814}, abstract = {

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.

}, keywords = {LTER-MCM}, issn = {0091-7613}, doi = {10.1130/G45048.1}, url = {https://pubs.geoscienceworld.org/gsa/geology/article/545184/Barium-and-barite-dynamics-in-Antarctic-streams}, author = {Saelens, Elsa D. and Christopher B. Gardner and Kathleen A. Welch and Sue Welch and W. Berry Lyons} } @article {4157, title = {Fe and Nutrients in Coastal Antarctic Streams: Implications for Primary Production in the Ross Sea}, journal = {Journal of Geophysical Research: Biogeosciences}, volume = {123}, year = {2018}, month = {12/2018}, pages = {3507 - 3522}, abstract = {

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.

}, keywords = {LTER-MCM}, issn = {2169-8953}, doi = {10.1029/2017JG004352}, url = {https://agupubs.pericles-prod.literatumonline.com/doi/full/10.1029/2017JG004352}, author = {Sydney A. Olund and W. Berry Lyons and Sue Welch and Kathleen A. Welch} } @article {4106, title = {The impact of fossil fuel burning related to scientific activities in the McMurdo Dry Valleys, Antarctica: Revisited}, journal = {Elementa: Science of the Anthropocene}, volume = {6}, year = {2018}, month = {04/2018}, abstract = {

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.

}, keywords = {LTER-MCM, carbon dynamics, emissions, fossil fuels, helicopter, management, McMurdo Dry Valleys, nitrogen, science activites}, doi = {10.1525/elementa.288}, url = {https://www.elementascience.org/article/10.1525/elementa.288/}, author = {W. Berry Lyons and Saelens, Elsa D. and Kathleen A. Welch} } @article {4068, title = {Near-surface refractory black carbon observations in the atmosphere and snow in the McMurdo Dry Valleys, Antarctica and potential impacts of foehn winds}, journal = {Journal of Geophysical Research: Atmospheres}, volume = {123}, year = {2018}, month = {01/2018}, pages = {2877 - 2887}, abstract = {

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.\ 

}, keywords = {LTER-MCM}, doi = {10.1002/2017JD027696}, url = {http://doi.wiley.com/10.1002/2017JD027696}, author = {Khan, Alia L. and McMeeking, Gavin and Schwarz, Joshua P. and Xian, Peng and Kathleen A. Welch and W. Berry Lyons and Diane M. McKnight} } @article {4027, title = {Ca isotopic geochemistry of an Antarctic aquatic system}, journal = {Geophysical Research Letters}, volume = {44}, year = {2017}, month = {01/2017}, pages = {882 - 891}, abstract = {

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.\ 

}, keywords = {LTER-MCM}, doi = {10.1002/2016GL071169}, url = {http://onlinelibrary.wiley.com/doi/10.1002/2016GL071169/full}, author = {W. Berry Lyons and Bullen, T and Kathleen A. Welch} } @article {4026, title = {A temporal stable isotopic (δ18O, δD, d-excess) comparison in glacier meltwater streams, Taylor Valley, Antarctica}, journal = {Hydrological Processes}, volume = {31}, year = {2017}, month = {08/2017}, pages = {3069 - 3083}, abstract = {

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.\ 

}, keywords = {LTER-MCM}, doi = {10.1002/hyp.v31.1710.1002/hyp.11245}, url = {http://onlinelibrary.wiley.com/doi/10.1002/hyp.11245/full}, author = {Leslie, D.L. and Kathleen A. Welch and W. Berry Lyons} } @article {3714, title = {Evidence for dispersal and habitat controls on pond diatom communities from the McMurdo Sound Region of Antarctica}, journal = {Polar Biology}, year = {2016}, month = {02/2016}, keywords = {LTER-MCM}, issn = {0722-4060}, doi = {10.1007/s00300-016-1901-6}, url = {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}, author = {Sakaeva, A. and Eric R. Sokol and Tyler J. Kohler and Lee F. Stanish and Sarah A. Spaulding and Howkins, Adrian and Kathleen A. Welch and W. Berry Lyons and John E. Barrett and Diane M. McKnight} } @article {3875, title = {Stream biogeochemical and suspended sediment responses to permafrost degradation in stream banks in Taylor Valley, Antarctica}, journal = {Biogeosciences}, volume = {13}, year = {2016}, month = {03/2016}, pages = {1723 - 1732}, abstract = {

\ 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.

}, keywords = {LTER-MCM}, doi = {10.5194/bg-13-1723-2016}, url = {http://www.biogeosciences.net/13/1723/2016/bg-13-1723-2016.pdf}, author = {Michael N. Gooseff and David J. Van Horn and Sudman, Zachary and Diane M. McKnight and Kathleen A. Welch and W. Berry Lyons} } @article {3306, title = {Antarctic streams as a potential source of iron for the Southern Ocean: Figure 1.}, journal = {Geology}, volume = {43}, year = {2015}, month = {11/2016}, pages = {1003 - 1006}, chapter = {1003}, abstract = {

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\ 

}, keywords = {LTER-MCM}, issn = {0091-7613}, doi = {10.1130/G36989.1}, url = {http://geology.gsapubs.org/lookup/doi/10.1130/G36989.1http://geology.geoscienceworld.org/lookup/doi/10.1130/G36989.1}, author = {W. Berry Lyons and Dailey, Kelsey R. and Kathleen A. Welch and Deuerling, Kelly M. and Sue Welch and Diane M. McKnight} } @article {3204, title = {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}, journal = {Chemical Geology}, volume = {404}, year = {2015}, month = {05/2015}, pages = {110 - 125}, chapter = {110}, abstract = {

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.

}, keywords = {LTER-MCM}, issn = {00092541}, doi = {10.1016/j.chemgeo.2015.03.029}, url = {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}, author = {Yang, Ningfang and Kathleen A. Welch and Mohajerin, T. Jade and Telfeyan, Katherine and Chevis, Darren A. and Grimm, Deborah A. and W. Berry Lyons and White, Christopher D. and Johannesson, Karen H.} } @article {3210, title = {Experimental formation of pore fluids in McMurdo Dry Valleys soils}, journal = {Antarctic Science}, volume = {27}, year = {2015}, month = {04/2015}, pages = {163 - 171}, abstract = {

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.

}, keywords = {LTER-MCM}, issn = {0954-1020}, doi = {10.1017/S0954102014000479}, url = {http://www.journals.cambridge.org/abstract_S0954102014000479}, author = {Joseph S. Levy and Andrew G Fountain and W. Berry Lyons and Kathleen A. Welch} } @article {3205, title = {Patterns and processes of salt efflorescences in the McMurdo region, Antarctica}, journal = {Artic, Antarctic and Alpine Research}, year = {2015}, abstract = {

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.

}, keywords = {LTER-MCM}, url = {http://aaarjournal.org/doi/abs/10.1657/AAAR0014-024}, author = {Bisson, K. M. and Kathleen A. Welch and Sue Welch and Sheets, J. M. and W. Berry Lyons and Joseph S. Levy and Andrew G Fountain} } @article {3189, title = {Pressure-driven, shoreline currents in a perennially ice-covered, pro-glacial lake in Antarctica, identified from a LiCl tracer injected into a pro-glacial stream}, journal = {Hydrological Processes}, volume = {29}, year = {2015}, month = {05-2015}, pages = {2212 - 2231}, abstract = {

The distribution of streamwater within ice-covered lakes influences sub-ice currents, biological activity and shoreline morphology. Perennially ice-covered lakes in the McMurdo Dry Valleys, Antarctica, provide an excellent natural laboratory to study hydrologic\–limnologic interactions under ice cover. For a 2\ h period on 17 December 2012, we injected a lithium chloride tracer into Andersen Creek, a pro-glacial stream flowing into Lake Hoare. Over 4\ h, we collected 182 water samples from five stream sites and 15 ice boreholes. Geochemical data showed that interflow travelled West of the stream mouth along the shoreline and did not flow towards the lake interior. The chemistry of water from Andersen Creek was similar to the chemistry of water below shoreline ice. Additional evidence for Westward flow included the morphology of channels on the ice surface, the orientation of ripple marks in lake sediments at the stream mouth and equivalent temperatures between Andersen Creek and water below shoreline ice. Streamwater deflected to the right of the mouth of the stream, in the opposite direction predicted by the Coriolis force. Deflection of interflow was probably caused by the diurnal addition of glacial runoff and stream discharge to the Eastern edge of the lake, which created a strong pressure gradient sloping to the West. This flow directed stream momentum away from the lake interior, minimizing the impact of stream momentum on sub-ice currents. It also transported dissolved nutrients and suspended sediments to the shoreline region instead of the lake interior, potentially affecting biological productivity and bedform development.

}, keywords = {LTER-MCM}, doi = {10.1002/hyp.v29.910.1002/hyp.10352}, url = {http://doi.wiley.com/10.1002/hyp.v29.9http://doi.wiley.com/10.1002/hyp.10352}, author = {Castendyk, Devin and Diane M. McKnight and Kathleen A. Welch and Niebuhr, Spencer and Chris Jaros} } @article {3203, title = {Boron isotopic geochemistry of the McMurdo Dry Valley lakes, Antarctica}, journal = {Chemical Geology}, volume = {386}, year = {2014}, month = {10/2014}, pages = {152 - 164}, chapter = {152}, abstract = {

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.

}, keywords = {LTER-MCM}, issn = {00092541}, doi = {10.1016/j.chemgeo.2014.08.016}, url = {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}, author = {Leslie, D.L. and W. Berry Lyons and Warner, Nathaniel and Vengosh, Avner and Olesik, J and Kathleen A. Welch and Deuerling, Kelly} } @article {1093, title = {The carbon stable isotope biogeochemistry of streams, Taylor Valley, Antarctica}, journal = {Applied Geochemistry}, volume = {32}, year = {2013}, month = {05/2013}, pages = {26 - 36}, keywords = {LTER-MCM}, doi = {10.1016/j.apgeochem.2012.08.019}, author = {W. Berry Lyons and Leslie, D.L. and Harmon, R.S. and Klaus Neumann and Kathleen A. Welch and Bisson, K. M. and Diane M. McKnight} } @article {1082, title = {Do Cryoconite Holes have the Potential to be Significant Sources of C, N, and P to Downstream Depauperate Ecosystems of Taylor Valley, Antarctica?}, journal = {Arctic, Antarctic, and Alpine Research}, volume = {45}, year = {2013}, month = {11/2013}, pages = {440 - 454}, keywords = {LTER-MCM}, doi = {10.1657/1938-4246-45.4.440}, author = {Bagshaw, Elizabeth and Martyn Tranter and Andrew G Fountain and Kathleen A. Welch and Hassan J. Basagic and W. Berry Lyons} } @article {1086, title = {Garwood Valley, Antarctica: A new record of Last Glacial Maximum to Holocene glaciofluvial processes in the McMurdo Dry Valleys}, journal = {Geological Society of America Bulletin}, volume = {125}, year = {2013}, month = {09/2013}, pages = {1484 - 1502}, keywords = {LTER-MCM}, doi = {10.1130/B30783.1}, url = {http://bulletin.geoscienceworld.org/content/early/2013/06/07/B30783.1.abstract}, author = {Joseph S. Levy and Andrew G Fountain and O{\textquoteright}Connor, J. E. and Kathleen A. Welch and W. Berry Lyons} } @article {1100, title = {Water track modification of soil ecosystems in the Lake Hoare basin, Taylor Valley, Antarctica}, journal = {Antarctic Science}, year = {2013}, pages = {1 - 10}, keywords = {LTER-MCM}, doi = {10.1017/S095410201300045X}, author = {Joseph S. Levy and Andrew G Fountain and Michael N. Gooseff and John E. Barrett and Robert Vantreese and Kathleen A. Welch and W. Berry Lyons and Uffe N. Nielsen and Diana H. Wall} } @article {1104, title = {The geochemistry of upland ponds, Taylor Valley, Antarctica}, journal = {Antarctic Science}, volume = {24}, year = {2012}, month = {2/2012}, pages = {3 - 14}, keywords = {LTER-MCM}, doi = {10.1017/S0954102011000617}, url = {http://journals.cambridge.org/action/displayAbstract?fromPage=online\&aid=8483351}, author = {W. Berry Lyons and Kathleen A. Welch and Christopher B. Gardner and Chris Jaros and Daryl L. Moorhead and Knoepfle, J and Peter T. Doran} } @article {1121, title = {Hypersaline {\textquotedblleft}wet patches{\textquotedblright} in Taylor Valley, Antarctica}, journal = {Geophysical Research Letters}, volume = {39}, year = {2012}, month = {03/2012}, keywords = {LTER-MCM}, doi = {10.1029/2012GL050898}, author = {Joseph S. Levy and Andrew G Fountain and Kathleen A. Welch and W. Berry Lyons} } @article {1133, title = {Water tracks and permafrost in Taylor Valley, Antarctica: Extensive and shallow groundwater connectivity in a cold desert ecosystem}, journal = {Geological Society of America Bulletin}, volume = {123}, year = {2011}, month = {11/2011}, pages = {2295-2311}, keywords = {LTER-MCM}, doi = {10.1130/B30436.1}, url = {http://bulletin.geoscienceworld.org/content/123/11-12/2295.short}, author = {Joseph S. Levy and Andrew G Fountain and Michael N. Gooseff and Kathleen A. Welch and W. Berry Lyons} } @article {1154, title = {Spatial variations in the geochemistry of glacial meltwater streams in the Taylor Valley, Antarctica}, journal = {Antarctic Science}, volume = {22}, year = {2010}, month = {12/2010}, pages = {662 - 672}, keywords = {LTER-MCM}, doi = {10.1017/S0954102010000702}, url = {http://www.montana.edu/lkbonney/DOCS/Publications/WelchEtAl2010Geochemistry.pdf}, author = {Kathleen A. Welch and W. Berry Lyons and Whisner, Carla and Christopher B. Gardner and Michael N. Gooseff and Diane M. McKnight and John C. Priscu} } @article {1185, title = {Composition and Biodegradation of a Synthetic Oil Spilled on the Perennial Ice Cover of Lake Fryxell, Antarctica}, journal = {Environmental Science \& Technology}, volume = {43}, year = {2009}, pages = {2708-2713}, keywords = {LTER-MCM}, doi = {LTER}, author = {Jaraula, C and Kenig, Fabien and Peter T. Doran and John C. Priscu and Kathleen A. Welch} } @article {1223, title = {SPME-GCMS study of the natural attenuation of aviation diesel spilled on the perennial ice cover of Lake Fryxell, Antarctica}, journal = {Science of the Total Environment}, volume = {407}, year = {2008}, pages = {250-262}, keywords = {LTER-MCM}, author = {Jaraula, C and Kenig, Fabien and Peter T. Doran and John C. Priscu and Kathleen A. Welch} } @article {1239, title = {The biogeochemical evolution of cryoconite holes on glaciers in Taylor Valley, Antarctica}, journal = {Journal of Geophysical Research}, volume = {113}, year = {2007}, pages = {G04S35}, keywords = {LTER-MCM}, doi = {LTER}, author = {Bagshaw, Elizabeth and Martyn Tranter and Andrew G Fountain and Kathleen A. Welch and Hassan J. Basagic and W. Berry Lyons} } @article {1247, title = {Organic carbon in Antarctic precipitation}, journal = {Geophysical Research Letters}, volume = {34}, year = {2007}, keywords = {LTER-MCM}, doi = {LTER}, author = {W. Berry Lyons and Kathleen A. Welch and Doggett, J} } @article {1235, title = {Reactivation of a cryptobiotic stream ecosystem in the McMurdo Dry Valleys, Antarctica: A long-term geomorphological experiment}, journal = {Geomorphology}, volume = {89}, year = {2007}, month = {09/2007}, pages = {186-204}, keywords = {LTER-MCM}, doi = {10.1016/j.geomorph.2006.07.025}, author = {Diane M. McKnight and Cathy M. Tate and Edmund D. Andrews and Dev K. Niyogi and Cozzetto, K and Kathleen A. Welch and W. Berry Lyons and D. G. Capone} } @article {1237, title = {Solute and isotope geochemistry of subsurface ice melt seeps in Taylor Valley, Antarctica}, journal = {Geological Society of America Bulletin}, volume = {119}, year = {2007}, month = {01/2007}, pages = {548-555}, keywords = {LTER-MCM, Climate Response}, doi = {10.1130/B25913.1}, url = {http://gsabulletin.gsapubs.org/content/119/5-6/548.short}, author = {Harris, K and Anne E. Carey and Kathleen A. Welch and W. Berry Lyons and Andrew G Fountain} } @article {1259, title = {The aeolian flux of calcium, chloride and nitrate to the McMurdo Dry Valleys landscape: Evidence from snow pit analysis}, journal = {Antarctic Science}, volume = {18}, year = {2006}, pages = {497-505}, keywords = {LTER-MCM}, doi = {LTER}, author = {Witherow, R and Bertler, N and Kathleen A. Welch and W. Berry Lyons and Paul A. Mayewski and Sneed, S and Thomas H. Nylen and Handley, M and Andrew G Fountain} } @inbook {1260, title = {Antarctic lake systems and climate change}, booktitle = {Trends in Antarctic Terrestrial and Limnetic Ecosystems: Antarctica as a Global Indicator}, year = {2006}, publisher = {S}, organization = {S}, address = {Dordrecht, The Netherlands}, keywords = {LTER-MCM}, doi = {LTER}, author = {W. Berry Lyons and Johanna Laybourn-Parry and Kathleen A. Welch and John C. Priscu}, editor = {D.M. Bergstrom and Peter Convey and A.H.L. Huiskes} } @article {1292, title = {The chemical composition of runoff from Canada Glacier, Antarctica: implications for glacier hydrology during a cool summer}, journal = {Annals of Glaciology}, volume = {40}, year = {2005}, pages = {15-19}, keywords = {LTER-MCM}, doi = {LTER}, author = {Martyn Tranter and Andrew G Fountain and W. Berry Lyons and Thomas H. Nylen and Kathleen A. Welch} } @article {1294, title = {Dating water and solute additions to ice-covered Antarctic lakes}, journal = {Geochimica et Cosmochimica Acta}, volume = {69}, year = {2005}, pages = {A720}, keywords = {LTER-MCM}, author = {W. Berry Lyons and Carolyn Dowling and Kathleen A. Welch and Snyder, G and Robert J. Poreda and Peter T. Doran and Andrew G Fountain} } @article {1297, title = {The Geochemistry of Supraglacial Streams of Canada Glacier, Taylor Valley (Antarctica), and their Evolution into Proglacial Waters}, journal = {Aquatic Geochemistry}, volume = {11}, year = {2005}, pages = {391-412}, keywords = {LTER-MCM}, author = {Sarah Fortner and Martyn Tranter and Andrew G Fountain and W. Berry Lyons and Kathleen A. Welch} } @article {1299, title = {Groundwater seeps in Taylor Valley Antarctica: An example of a subsurface melt event}, journal = {Annals of Glaciology}, volume = {40}, year = {2005}, pages = {200-206}, keywords = {LTER-MCM}, doi = {LTER}, author = {W. Berry Lyons and Kathleen A. Welch and Anne E. Carey and Diana H. Wall and Ross A. Virginia and Andrew G Fountain and Peter T. Doran and Csatho, B and Tremper, C} } @article {1300, title = {Halogen geochemistry of the McMurdo Dry Valleys Lakes, Antarctica: clues to the origin of solutes and lake evolution}, journal = {Geochimica et Cosmochimica Acta}, volume = {69}, year = {2005}, pages = {305-323}, keywords = {LTER-MCM}, author = {W. Berry Lyons and Kathleen A. Welch and Snyder, G and Olesik, J and Graham, E and G. M. Marion and Robert J. Poreda} } @article {1305, title = {Perturbation of hydrochemical conditions in natural microcosms entombed within Antarctic ice}, journal = {Ice and Climate News}, volume = {6}, year = {2005}, pages = {22-23}, keywords = {LTER-MCM}, author = {Martyn Tranter and Andrew G Fountain and Christian H. Fritsen and W. Berry Lyons and John C. Priscu and Stratham, P and Kathleen A. Welch} } @article {1324, title = {The Carbon Isotopic Composition of Dissolved Inorganic Carbon in Perennially Ice-Covered Antarctica Lakes: Searching for a Biogenic Signature.}, journal = {Annals of Glaciology}, volume = {39}, year = {2004}, keywords = {LTER-MCM}, author = {Klaus Neumann and W. Berry Lyons and John C. Priscu and David J. DesMarais and Kathleen A. Welch} } @article {1331, title = {Extreme hydrochemical conditions in natural microcosms entombed within Antarctic ice.}, journal = {Hydrological Processes}, volume = {18}, year = {2004}, pages = {379-387}, keywords = {LTER-MCM}, author = {Martyn Tranter and Andrew G Fountain and Christian H. Fritsen and W. Berry Lyons and John C. Priscu and Stathan, P and Kathleen A. Welch} } @article {1358, title = {Biochemistry of Si in the McMurdo Dry Valley lakes, Antarctica}, journal = {The International Journal of Astrobiology}, volume = {1}, year = {2003}, pages = {737-749}, keywords = {LTER-MCM}, author = {Pugh, H and Kathleen A. Welch and W. Berry Lyons and John C. Priscu and Diane M. McKnight} } @inbook {1360, title = {Chemistry and lake dynamics of the Taylor Valley lakes, Antarctica: The importance of long-term monitoring.}, booktitle = {Antarctic Ecosystems: Models for Wider Ecological Understanding}, year = {2003}, publisher = {Caxton Press}, organization = {Caxton Press}, keywords = {LTER-MCM}, author = {Kathleen A. Welch and Klaus Neumann and W. Berry Lyons and Diane M. McKnight}, editor = {Clive Howard-Williams and W. Davidson and P. Broady} } @article {1368, title = {Strontium isotopic signatures of the streams and lakes of Taylor Valley, southern Victoria Land, Antarctica: chemical weathering in a polar climate}, journal = {Aquatic Geochemistry}, volume = {8}, year = {2003}, pages = {875-895}, keywords = {LTER-MCM}, author = {W. Berry Lyons and C. A. Nezat and Benson, L and Bullen, T and Graham, E and Kidd, J and Kathleen A. Welch and Thomas, J} } @article {1369, title = {Surface glaciochemistry of Taylor Valley, southern Victoria Land, Antarctica and its relationship to stream chemistry.}, journal = {Hydrological Processes}, volume = {17}, year = {2003}, pages = {115-130}, keywords = {LTER-MCM}, author = {W. Berry Lyons and Kathleen A. Welch and Andrew G Fountain and Gayle L. Dana and Bruce H. Vaughn and Diane M. McKnight} } @article {1400, title = {Chemical weathering in streams of a polar desert (Taylor Valley, Antarctica).}, journal = {GSA Bulletin}, volume = {113}, year = {2001}, pages = {1401-1408}, keywords = {LTER-MCM}, author = {C. A. Nezat and W. Berry Lyons and Kathleen A. Welch} } @article {1404, title = {The McMurdo Dry Valleys Long-Term Ecological Research Program: new understanding of the biogeochemistry of the Dry Valley lakes: a review.}, journal = {Polar Geography}, volume = {25}, year = {2001}, pages = {202-217}, keywords = {LTER-MCM}, author = {W. Berry Lyons and Kathleen A. Welch and John C. Priscu and Johanna Laybourn-Parry and Daryl L. Moorhead and Diane M. McKnight and Peter T. Doran and Martyn Tranter} } @inbook {1426, title = {Climate and hydrologic variations and implications for lake and stream ecological response in the McMurdo Dry Valleys, Antarctica}, booktitle = {Climate Variability and Ecosystem Response at Long Term Ecological Research Sites}, year = {2000}, pages = {174-195}, publisher = {Oxford University Press}, organization = {Oxford University Press}, keywords = {LTER-MCM}, author = {Kathleen A. Welch and W. Berry Lyons and Diane M. McKnight and Chris Jaros and Andrew G Fountain and Thomas H. Nylen and Peter T. Doran and Clive Howard-Williams}, editor = {D. Greenland and D. G. Goodin and R. C. Smith} } @article {1430, title = {Fossil fuel burning in Taylor Valley, southern Victoria Land, Antarctica: estimating the role of scientific activities on carbon and nitrogen reservoirs and fluxes}, journal = {Environmental Science and Technology}, volume = {34}, year = {2000}, pages = {1659-1662}, keywords = {LTER-MCM}, author = {W. Berry Lyons and C. A. Nezat and Kathleen A. Welch and Kottmeier, S and Peter T. Doran} } @article {1432, title = {The importance of landscape position and legacy: The evolution of the Taylor Valley Lake District, Antarctica.}, journal = {Freshwater Biology}, volume = {43}, year = {2000}, pages = {355-367}, keywords = {LTER-MCM}, author = {W. Berry Lyons and Andrew G Fountain and Peter T. Doran and John C. Priscu and Klaus Neumann and Kathleen A. Welch} } @article {1451, title = {Chlorine-36 in the waters of the McMurdo Dry Valley lakes, southern Victoria Land, Antarctica: revisited}, journal = {Geochimica et Cosmochimica Acta}, volume = {62}, year = {1999}, pages = {185-191}, keywords = {LTER-MCM}, author = {W. Berry Lyons and Kathleen A. Welch and Pankaj Sharma} } @article {1459, title = {Geomicrobiology of sub-glacial ice above Vostok Station}, journal = {Science}, volume = {286}, year = {1999}, pages = {2141-2144}, keywords = {LTER-MCM}, doi = {10.1126/science.286.5447.2141}, author = {John C. Priscu and Edward E. Adams and W. Berry Lyons and Mary A. Voytek and David W. Mogk and Robert L. Brown and Christopher P. McKay and Cristina D. Takacs-Vesbach and Kathleen A. Welch and Craig F. Wolf and Julie D. Kirshtein and Recep Avci} } @article {1460, title = {History of McMurdo Dry Valley Lakes, Antarctica, from stable chlorine isotope data}, journal = {Geology}, volume = {27}, year = {1999}, keywords = {LTER-MCM}, doi = {LTER}, author = {W. Berry Lyons and Frape, S and Kathleen A. Welch} } @article {1467, title = {Mercury in aquatic systems in Antarctica}, journal = {Geophysical Research Letters}, volume = {26}, year = {1999}, pages = {2235-2238}, keywords = {LTER-MCM}, author = {W. Berry Lyons and Kathleen A. Welch and Jean-Claude Bonzongo} } @inbook {1499, title = {Geochemical Linkages Among Glaciers, Streams, and Lakes Within the Taylor Valley, Antarctica}, booktitle = {Ecosystem Processes in a Polar Desert: The McMurdo Dry Valleys, Antarctica}, volume = {72}, year = {1998}, pages = {77-92}, keywords = {LTER-MCM}, author = {W. Berry Lyons and Kathleen A. Welch and Klaus Neumann and Jeffrey K. Toxey and Robyn McArthur and Changela Williams and Diane M. McKnight and Daryl L. Moorhead} } @article {1507, title = {McMurdo Dry Valleys LTER: Density-driven mixing in Lake Hoare?}, journal = {Antarctic Journal of the United States - 1996 Review Issue (NSF 98-28)}, volume = {31}, year = {1998}, pages = {205}, keywords = {LTER-MCM}, author = {W. Berry Lyons and Kathleen A. Welch and Scott W. Tyler and Pankaj Sharma} } @inbook {1549, title = {Chemical weathering rates and reactions in the Lake Fryxell Basin, Taylor Valley : Comparison to temperate river basins}, booktitle = {Ecosystem Processes in Antarctic Ice-free Landscapes}, year = {1997}, pages = {147-154}, publisher = {Balkema Press, Rotterdam}, organization = {Balkema Press, Rotterdam}, keywords = {LTER-MCM}, author = {W. Berry Lyons and Kathleen A. Welch and C. A. Nezat and K. Crick and Jeffrey K. Toxey and J.A. Mastrine and Diane M. McKnight} } @inbook {1552, title = {Determination of rare earth elements in Antarctic lakes and streams of varying ionic strengths}, booktitle = {Plasma Source Mass Spectrometry: Developments and Applications}, year = {1997}, pages = {253-262}, publisher = {Royal Society of Chemistry}, organization = {Royal Society of Chemistry}, address = {London}, keywords = {LTER-MCM}, author = {Graham, E and Ramsey, L. A. and W. Berry Lyons and Kathleen A. Welch} } @inbook {1554, title = {Ecological processes in a cold desert ecosystem: the abundance and species distribution of algal mats in glacial meltwater streams in Taylor Valley}, booktitle = {Institute of Arctic and Alpine Research}, series = {Occasional Paper}, volume = {51}, year = {1997}, pages = {108 pp}, publisher = {University of Colorado}, organization = {University of Colorado}, keywords = {LTER-MCM}, url = {http://instaar.colorado.edu/other/download/OP51-ECOLOGICAL-PROCESSES.pdf}, author = {Alexander S. Alger and Diane M. McKnight and Sarah A. Spaulding and Cathy M. Tate}, editor = {Gordon H Shupe and Kathleen A. Welch and R. L. Edwards and Edmund D. Andrews} } @article {1557, title = {Lithium in waters of a polar desert}, journal = {Geochimica et Cosmochimica Acta}, volume = {61}, year = {1997}, pages = {4309-4319}, keywords = {LTER-MCM}, author = {W. Berry Lyons and Kathleen A. Welch} } @article {1569, title = {Determination of major element chemistry in terrestrial waters from Antarctica by ion chromatography}, journal = {Journal of Chromatography A}, volume = {739}, year = {1996}, pages = {257-263}, keywords = {LTER-MCM}, author = {Kathleen A. Welch and W. Berry Lyons and Graham, E and Klaus Neumann and James M. Thomas and D. Mikesell} } @article {1590, title = {McMurdo LTER: Comparative limnology of the Taylor Valley lakes: The major solutes}, journal = {Antarctic Journal of the U.S.}, volume = {30}, year = {1995}, pages = {292-293}, keywords = {LTER-MCM}, author = {Kathleen A. Welch and W. Berry Lyons} } @article {1617, title = {McMurdo LTER: Inorganic geochemical studies with special reference to calcium carbonate dynamics}, journal = {Antarctic Journal of the U.S.}, volume = {29}, year = {1994}, pages = {237-239}, keywords = {LTER-MCM}, author = {Kathleen A. Welch and W. Berry Lyons and John C. Priscu and R. L. Edwards and Diane M. McKnight and Harold R. House and Robert A. Wharton Jr.} }