TY - JOUR T1 - Spatial patterns of major ions and their relationship to sediment concentration in near surface glacier ice, Taylor Valley Antarctica JF - Journal of Geophysical Research: Earth Surface Y1 - 2023 A1 - Bergstrom, Anna J. A1 - Kathleen A. Welch A1 - Michael N. Gooseff AB -

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.

UR - https://onlinelibrary.wiley.com/doi/10.1029/2022JF006980 JO - JGR Earth Surface ER - TY - JOUR T1 - Diatoms in hyporheic sediments trace organic matter retention and processing in the McMurdo Dry Valleys, Antarctica JF - Journal of Geophysical Research: Biogeosciences Y1 - 2021 A1 - Heindel, Ruth C A1 - Darling, Joshua P. A1 - Singley, Joel G. A1 - Bergstrom, Anna J. A1 - Diane M. McKnight A1 - Lukkari, Braeden M. A1 - Kathleen A. Welch A1 - Michael N. Gooseff KW - benthic processes KW - biogenic silica KW - biogeochemical cycles processes and modeling KW - carbon cycling KW - diatoms KW - groundwater/surface water interactions KW - hyporheic zone KW - McMurdo Dry Valleys KW - nitrogen cycling KW - particulate organic matter AB -

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.

VL - 126 UR - https://agupubs.onlinelibrary.wiley.com/doi/10.1029/2020JG006097 IS - 2 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.

VL - 133 UR - https://pubs.geoscienceworld.org/gsa/gsabulletin/article/133/1-2/425/587799/Geochemistry-of-contrasting-stream-types-Taylor IS - 1/2 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 - Nutrient uptake in the supraglacial stream network of an Antarctic glacier JF - Journal of Geophysical Research: Biogeosciences Y1 - 2020 A1 - Bergstrom, Anna J. A1 - Michael N. Gooseff A1 - Singley, Joel G. A1 - Cohen, Matthew J. A1 - Kathleen A. Welch KW - McMurdo Dry Valleys KW - nitrogen KW - nutrient tracers KW - nutrient uptake KW - sediments KW - supraglacial streams AB -

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.

UR - https://agupubs.onlinelibrary.wiley.com/doi/abs/10.1029/2020JG005679 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 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 - 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 - 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 - 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 20102011 melt season using natural tracers. Water collection started at flow onset and continued, with weekly hyporheiczone sampling. The water δ18O and δD values were isotopically lighter in the beginning and heavier later in the season. Dexcess measurements were used as an indicator of mixing because an evaporative signature was evident and distinguishable between 2 primary endmembers (glacier meltwater and hyporheic zone). Hyporheiczone 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 hyporheiczone solute interaction through the influence from subsurface hypersaline flow. Overall, the evolution of Taylor Valley hyporheiczone hydrology is described seasonally. In midDecember, 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 zonestream 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 - 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 - 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 - 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 JF - Hydrological Processes Y1 - 2015 A1 - Castendyk, Devin A1 - Diane M. McKnight A1 - Kathleen A. Welch A1 - Niebuhr, Spencer A1 - Chris Jaros AB -

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.

VL - 29 UR - http://doi.wiley.com/10.1002/hyp.v29.9http://doi.wiley.com/10.1002/hyp.10352 IS - 9 JO - Hydrol. Process. 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 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 - 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 - 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 - JOUR T1 - Spatial variations in the geochemistry of glacial meltwater streams in the Taylor Valley, Antarctica JF - Antarctic Science Y1 - 2010 A1 - Kathleen A. Welch A1 - W. Berry Lyons A1 - Whisner, Carla A1 - Christopher B. Gardner A1 - Michael N. Gooseff A1 - Diane M. McKnight A1 - John C. Priscu VL - 22 UR - http://www.montana.edu/lkbonney/DOCS/Publications/WelchEtAl2010Geochemistry.pdf IS - 06 ER - TY - JOUR T1 - Composition and Biodegradation of a Synthetic Oil Spilled on the Perennial Ice Cover of Lake Fryxell, Antarctica JF - Environmental Science & Technology Y1 - 2009 A1 - Jaraula, C A1 - Kenig, Fabien A1 - Peter T. Doran A1 - John C. Priscu A1 - Kathleen A. Welch VL - 43 ER - TY - JOUR T1 - SPME-GCMS study of the natural attenuation of aviation diesel spilled on the perennial ice cover of Lake Fryxell, Antarctica JF - Science of the Total Environment Y1 - 2008 A1 - Jaraula, C A1 - Kenig, Fabien A1 - Peter T. Doran A1 - John C. Priscu A1 - Kathleen A. Welch VL - 407 ER - TY - JOUR T1 - The biogeochemical evolution of cryoconite holes on glaciers in Taylor Valley, Antarctica JF - Journal of Geophysical Research Y1 - 2007 A1 - Bagshaw, Elizabeth A1 - Martyn Tranter A1 - Andrew G Fountain A1 - Kathleen A. Welch A1 - Hassan J. Basagic A1 - W. Berry Lyons VL - 113 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 - 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 - 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 - 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 - 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 - 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 - 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 - 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 - 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 - 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 - 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 - 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 - 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 - 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 - 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 - 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 - 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 - CHAP T1 - Ecological processes in a cold desert ecosystem: the abundance and species distribution of algal mats in glacial meltwater streams in Taylor Valley T2 - Institute of Arctic and Alpine Research Y1 - 1997 A1 - Alexander S. Alger A1 - Diane M. McKnight A1 - Sarah A. Spaulding A1 - Cathy M. Tate ED - Gordon H Shupe ED - Kathleen A. Welch ED - R. L. Edwards ED - Edmund D. Andrews JF - Institute of Arctic and Alpine Research T3 - Occasional Paper PB - University of Colorado VL - 51 UR - http://instaar.colorado.edu/other/download/OP51-ECOLOGICAL-PROCESSES.pdf 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 - 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 -