@article {4942, title = {The distribution of surface soil moisture over space and time in eastern Taylor Valley, Antarctica}, journal = {Remote Sensing}, volume = {15}, year = {2023}, month = {06/2023}, pages = {3170}, abstract = {

Available soil moisture is thought to be the limiting factor for most ecosystem processes in the cold polar desert of the McMurdo Dry Valleys (MDVs) of Antarctica. Previous studies have shown that microfauna throughout the MDVs are capable of biological activity when sufficient soil moisture is available (~2\–10\% gravimetric water content), but few studies have attempted to quantify the distribution, abundance, and frequency of soil moisture on scales beyond that of traditional field work or local field investigations. In this study, we present our work to quantify the soil moisture content of soils throughout the Fryxell basin using multispectral satellite remote sensing techniques. Our efforts demonstrate that ecologically relevant abundances of liquid water are common across the landscape throughout the austral summer. On average, the Fryxell basin of Taylor Valley is modeled as containing 1.5 \± 0.5\% gravimetric water content (GWC) across its non-fluvial landscape with ~23\% of the landscape experiencing an average GWC \> 2\% throughout the study period, which is the observed limit of soil nematode activity. These results indicate that liquid water in the soils of the MDVs may be more abundant than previously thought, and that the distribution and availability of liquid water is dependent on both soil properties and the distribution of water sources. These results can also help to identify ecological hotspots in the harsh polar Antarctic environment and serve as a baseline for detecting future changes in the soil hydrological regime.

}, keywords = {LTER-MCM, Dry valleys, ecology, hydrology, remote sensing, soil moisture}, doi = {10.3390/rs15123170}, url = {https://www.mdpi.com/2072-4292/15/12/3170}, author = {Salvatore, Mark R. and Barrett, John E. and Fackrell, Laura E. and Sokol, Eric R. and Levy, Joseph S. and Kuentz, Lily C. and Gooseff, Michael N. and Adams, Byron J. and Power, Sarah N. and Knightly, J. Paul and Matul, Haley M. and Szutu, Brian and Doran, Peter T.} } @article {4691, title = {Episodic basin-scale soil moisture anomalies associated with high relative humidity events in the McMurdo Dry Valleys, Antarctica}, journal = {Antarctic Science}, year = {2021}, month = {08/2021}, pages = {1-15}, abstract = {

Outside of hydrologically wetted active layer soils and humidity-sensitive soil brines, low soil moisture is a limiting factor controlling biogeochemical processes in the McMurdo Dry Valleys. But anecdotal field observations suggest that episodic wetting and darkening of surface soils in the absence of snowmelt occurs during high humidity conditions. Here, I analyse long-term meteorological station data to determine whether soil-darkening episodes are present in the instrumental record and whether they are, in fact, correlated with relative humidity. A strong linear correlation is found between relative humidity and soil reflectance at the Lake Bonney long-term autonomous weather station. Soil reflectance is found to decrease annually by a median of 27.7\% in response to high humidity conditions. This magnitude of darkening is consistent with soil moisture rising from typical background values of \< 0.5 wt.\% to 2\–3 wt.\%, suggesting that regional atmospheric processes may result in widespread soil moisture generation in otherwise dry surface soils. Temperature and relative humidity conditions under which darkening is observed occur for hundreds of hours per year, but are dominated by episodes occurring between midnight and 07h00 local time, suggesting that wetting events may be common, but are not widely observed during typical diel science operations.

}, keywords = {LTER-MCM, deliquescence, hydrology, microclimate, micrometeorology, pedology, remote sensing}, issn = {0954-1020}, doi = {10.1017/S0954102021000341}, url = {https://www.cambridge.org/core/product/identifier/S0954102021000341/type/journal_article}, author = {Joseph S. Levy} } @article {4449, title = {Remote characterization of photosynthetic communities in the Fryxell basin of Taylor Valley, Antarctica}, journal = {Antarctic Science}, year = {2020}, month = {03/2020}, abstract = {

We investigate the spatial distribution, spectral properties and temporal variability of primary producers (e.g. communities of microbial mats and mosses) throughout the Fryxell basin of Taylor Valley, Antarctica, using high-resolution multispectral remote-sensing data. Our results suggest that photosynthetic communities can be readily detected throughout the Fryxell basin based on their unique near-infrared spectral signatures. Observed intra- and inter-annual variability in spectral signatures are consistent with short-term variations in mat distribution, hydration and photosynthetic activity. Spectral unmixing is also implemented in order to estimate mat abundance, with the most densely vegetated regions observed from orbit correlating spatially with some of the most productive regions of the Fryxell basin. Our work establishes remote sensing as a valuable tool in the study of these ecological communities in the McMurdo Dry Valleys and demonstrates how future scientific investigations and the management of specially protected areas could benefit from these tools and techniques.

}, keywords = {LTER-MCM, ecology, hydrology, McMurdo Dry Valleys, microbiology, remote sensing, spectroscopy}, doi = {10.1017/S0954102020000176}, url = {https://www.cambridge.org/core/journals/antarctic-science/article/remote-characterization-of-photosynthetic-communities-in-the-fryxell-basin-of-taylor-valley-antarctica/8576F6BB1BCFDCA8409F5EA96CA00C6F}, author = {Salvatore, Mark R. and Borges, Schuyler R. and John E. Barrett and Eric R. Sokol and Lee F. Stanish and Power, Sarah N. and Morin, Paul} } @phdthesis {4189, title = {Biogeochemistry, contaminant transport, and atmospheric exchange in glacial cryoconite meltwater of the McMurdo Dry Valleys, Antarctica}, volume = {Ph.D.}, year = {2018}, month = {2018}, pages = {245}, school = {University of Colorado}, type = {doctoral}, address = {Boulder, CO}, abstract = {

Polar regions serve as a global sink for many forms of semi-volatile pollution emitted from low- or midlatitudes of the populated world. This study examined the longrange atmospheric transport, fate, and phase partitioning of semi-volatile organic contaminants from air masses into meltwater and aeolian sediment on six glaciers in the McMurdo Dry Valleys of Antarctica. A novel low-cost, field-portable instrument was developed for the in-situ solid-phase extraction of trace contaminants in extreme environmental conditions without access to electricity or traditional laboratory facilities. Beyond polar research, this equipment is applicable for rapid field extraction and stabilization of samples assessing air and water quality after natural disasters. This is the first published study to identify the presence of anthropogenic perfluorinated compounds in the Transantarctic Mountain region and indicates a longer range of poleward contaminant transport than prior estimates in the Southern Hemisphere. Additional research examined the biochemistry and climatic variability of open and sealed cryoconite holes on glacial surfaces throughout the initial melt, equilibrium, and refreezing periods in 2013\–2015. High solute concentrations relative to glacial ice indicate that the pools can remain isolated from hydrologic connectivity for more than a decade. Microbial carbon cycling in pools enclosed by ice led to atmospheric disequilibrium and extreme pH. Analysis of unique air, liquid, and ice stratification in cryoconite holes revealed vertical patterns representing a highly accurate, multi-year record of past weather conditions sensitive enough to identify individual dates. This research identifies fluctuations in atmospheric contaminant transport, specific timeframes for deposition events, and may be used in back-trajectory models to help identify the source and variability of semi-volatile emissions in the Southern hemisphere.

}, keywords = {LTER-MCM, Antarctica, applied sciences, contaminant transport, cryoconite, earth sciences, glacier, hydrology, melt}, url = {https://search.proquest.com/docview/2048314678}, author = {Mass, Alex Q. and Diane M. McKnight} } @mastersthesis {4162, title = {Modeling nitrate concentrations in an Antarctic glacial meltwater stream under fluctuating hydrologic conditions and nitrate inputs}, volume = {M.S.}, year = {2012}, school = {Pennsylvania State University}, type = {masters}, abstract = {

The McMurdo Dry Valleys comprise a unique polar desert ecosystem in Victoria Land, Antarctica. The hydrologic system in the Dry Valleys is often characterized as being simplified compared to temperate watersheds, due to the ability to identify physical boundaries and nutrient sources and sinks. We seek to characterize the evolution of streamflow, solutes, and nutrients along a glacial meltwater stream in the McMurdo Dry Valleys, and to understand the role of different sources and sinks under varying hydrologic conditions. The study presented here includes streamflow routing, solute modeling, and nitrate concentration modeling in Von Guerard stream, a stream with abundant algal coverage in the McMurdo Dry Valleys region of Antarctica. The streamflow model is a solution to the kinematic wave routing problem. Solute modeling addresses advection, dispersion, as well as hyporheic zone inputs, which are controlled by weathering and hyporheic exchange. Lastly, the nitrate model builds on the solute model with the addition of a gross primary production (GPP) component. Results indicate that the hyporheic source of nitrate is controlling due to rapid exchange with the main channel. GPP impacts are small due to light-saturated conditions for a majority of the season, but provide a consistent sink for nitrate. The role of advective and dispersive transport is highly dependent on flow conditions, with advective transport controlling at high flows and dispersive controlling at low flows.

}, keywords = {LTER-MCM, hydrology, hyporheic zone, nitrate, nutrients, primary productivity, stream}, url = {https://etda.libraries.psu.edu/catalog/15316}, author = {Bernzott, Emily D. and Michael N. Gooseff} } @mastersthesis {4163, title = {Hydrologic controls of nutrient fluxes in glacial meltwater streams at inter-annual, seasonal, and daily timescales in the McMurdo Dry Valleys, Antarctica}, volume = {M.S.}, year = {2011}, school = {Pennsylvania State University}, type = {masters}, abstract = {

In the McMurdo Dry Valleys of Antarctica, glaciers are hydrologically linked to closed-basin lakes at the valley floor by glacial meltwater streams. Streams flow through porous, well-defined channels with extensive chemically active hyporheic zones. Temporally varying dynamics of meltwater generation and sub-stream thaw depth are thought to control the potential for the hyporheic zone and benthic communities to influence transport of nutrients and dissolved ions downstream. Using the McMurdo LTER database, patterns in stream discharge, electrical conductivity (both with 15-minute sampling intervals), and solute chemistry (weekly sampling intervals) were examined on eight MDV streams from 1990-2008. Discharge and electrical conductivity values were highly variable among streams. Discharge values were highly dependent upon glacial source area, but meteorological and topographical complexities create large variability at all time scales. The longer streams were found to have much higher electrical conductivity values than the shorter streams, suggesting that there are more opportunities for hyporheic weathering reactions along longer stream reaches. Weekly sampled water solutes from each stream\&$\#$39;s entire record were plotted against the discharge recorded at the time when the sample was taken. Silicate concentrations displayed a decreasing logarithmic relationship, while nutrient concentrations had no apparent relationship. This suggests that with the exception to bioreactive solutes, the majority of hyporheic interactions could possibly be characterized by electrical conductivity and discharge. To attain information on in-stream nutrient dynamics and nutrient fluxes, glacial source water at the upper reach of Green Creek and stream outlet water at the lower reach of Green Creek were sampled hourly for two separate diel periods during the 2008-09 austral summer. Both dates were in late January under two distinct flow conditions (~0.5 L/s and ~10 L/s). Under low flow conditions, nutrient cycling was found to be uptake dominated. High flow conditions showed both uptake and regeneration with much higher nutrient loads, but as in the low flow conditions, no apparent temporal trends were found. Nutrient concentrations could not be predicted using the two parameters of discharge and electrical conductivity with in-stream nutrient dynamics likely too complicated at the sub-daily scale.

}, keywords = {LTER-MCM, Antarctica, biogeochemistry, chemical weathering, discharge, electrical conductivity, glacial melt, glaciers, hydrology, hyporheic, MCM LTER, McMurdo Dry Valleys, nutrient fluxes, nutrients, polar desert, solute chemistry, stream chemistry, streamflow, water chemistry}, url = {https://etda.libraries.psu.edu/catalog/11568}, author = {Weaver, Mitchell R. and Michael N. Gooseff} }