02505nas a2200325   4500008004100000022001400041245012700055210006900182260001200251300001800263490000800281520146500289653001701754653003701771653002401808653002401832100002701856700002101883700002301904700002201927700002201949700002501971700002001996700002202016700002202038700002202060700002202082700001402104856006102118       2023                        eng d  a2169-900300aCauses and characteristics of electrical resistivity variability in shallow (<4 m) soils in Taylor Valley, East Antarctica0 aCauses and characteristics of electrical resistivity variability  c02/2023  ae2022JF0066960 v1283 a<p>Airborne electromagnetic surveys collected in December 2011 and November 2018 and three soil sampling transects were used to analyze the spatial heterogeneity of shallow (&lt;4 m) soil properties in lower Taylor Valley (TV), East Antarctica. Soil resistivities from 2011 to 2018 ranged from &sim;33 Ωm to &sim;3,500 Ωm with 200 Ωm assigned as an upper boundary for brine-saturated sediments. Elevations below &sim;50 m above sea level (masl) typically exhibit the lowest resistivities with resistivity increasing at high elevations on steeper slopes. Soil water content was empirically estimated from electrical resistivities using Archie&#39;s Law and range from &sim;&lt;1% to &sim;68% by volume. An increase in silt- and clay-sized particles at low elevations increases soil porosity but decreases hydraulic conductivity, promoting greater residence times of soil water at low elevations near Lake Fryxell. Soil resistivity variability between 2011 and 2018 shows soils at different stages of soil freeze-thaw cycles, which are caused predominantly by solar warming of soils as opposed to air temperature. This study furthers the understanding of the hydrogeologic structure of the shallow subsurface in TV and identifies locations of soils that are potentially prone to greater rates of thaw and resulting ecosystem homogenization of soil properties from projected increases in hydrological connectivity across the region over the coming decades.</p>10aactive layer10aairborne electromagnetic surveys10aMcMurdo Dry Valleys10apermafrost dynamics1 aGutterman, William, S.1 aDoran, Peter, T.1 aVirginia, Ross, A.1 aBarrett, John, E.1 aMyers, Krista, F.1 aTulaczyk, Slawek, M.1 aFoley, Neil, T.1 aMikucki, Jill, A.1 aDugan, Hilary, A.1 aGrombacher, Denys1 aBording, Thue, S.1 aAuken, E.  uhttps://onlinelibrary.wiley.com/doi/10.1029/2022JF00669602179nas a2200121   4500008004100000245012700041210006900168260005300237490000900290520167300299100002701972856005801999       2021                        eng d00aCauses and characteristics of electrical resistivity variability in shallow (<4 m) soils in Taylor Valley, East Antarctica0 aCauses and characteristics of electrical resistivity variability  aBaton RougebLouisiana State Universityc07/20210 vM.S.3 a<p>The McMurdo Dry Valleys are the largest ice-free region in Antarctica and are characterized as a polar desert environment. Soils in the region are typically very dry (&lt;1% soil water by weight) and remain frozen for most of the year. Increases in air temperature and incoming solar radiation during the austral summer generate meltwater from glaciers, ground ice, and snow patches supplying moisture to soils and altering the physical and chemical makeup of the subsurface. Previous studies have utilized airborne electromagnetic surveys (AEM) to analyze groundwater systems in the deep subsurface but have not yet examined soil moisture in the shallow (&lt;4 m) subsurface. Here, I used electrical resistivity data from two AEM surveys (2011 and 2018) and soil geochemical data from three transects to characterize the spatial heterogeneity of soil properties in the near-subsurface of lower Taylor Valley. Soil resistivities from 2011 and 2018 range from 33.2 Ωm to 3535 Ωm with low elevations of &lt;100 meters above sea level (masl) typically displaying the lowest resistivities and high elevations displaying greater resistivities. Liquid brine fractions were empirically estimated from electrical resistivity values using Archie&rsquo;s Law and range from 0.3% to 68.2% for soils with resistivities &lt;200 Ωm. Additionally, soil transect data show greater percentages of fine-grained sediments (&lt;63 &micro;m) exist at elevations &lt;100 masl where soil resistivities begin decreasing. Resistivity variability in the subsurface is ultimately controlled by the site history, local and regional climate, soil salinity, soil moisture, soil lithology.</p>1 aGutterman, William, S.  uhttps://digitalcommons.lsu.edu/gradschool_theses/5411