02506nas a2200289   4500008004100000022001400041245006300055210006300118260001200181490000800193520169900201653001501900653001701915653001301932653001801945653001001963653001001973100002601983700002102009700001802030700001702048700002002065700002002085700002102105700001702126856007302143       2021                        eng d  a2169-895300aExploring the boundaries of microbial habitability in soil0 aExploring the boundaries of microbial habitability in soil  c06/20210 v1263 a<p>Microbes are widely assumed to be capable of colonizing even the most challenging terrestrial surface environments on Earth given enough time. We would not expect to find surface soils uninhabited by microbes as soils typically harbor diverse microbial communities and viable microbes have been detected in soils exposed to even the most inhospitable conditions. However, if uninhabited soils do exist, we might expect to find them in Antarctica. We analyzed 204 ice-free soils collected from across a remote valley in the Transantarctic Mountains (84&ndash;85&deg;S, 174&ndash;177&deg;W) and were able to identify a potential limit of microbial habitability. While most of the soils we tested contained diverse microbial communities, with fungi being particularly ubiquitous, microbes could not be detected in many of the driest, higher elevation soils&mdash;results that were confirmed using cultivation-dependent, cultivation-independent, and metabolic assays. While we cannot confirm that this subset of soils is completely sterile and devoid of microbial life, our results suggest that microbial life is severely restricted in the coldest, driest, and saltiest Antarctic soils. Constant exposure to these conditions for thousands of years has limited microbial communities so that their presence and activity is below detectable limits using a variety of standard methods. Such soils are unlikely to be unique to the studied region with this work supporting previous hypotheses that microbial habitability is constrained by near-continuous exposure to cold, dry, and salty conditions, establishing the environmental conditions that limit microbial life in terrestrial surface soils.</p>10aAntarctica10aastrobiology10abacteria10aextremophiles10afungi10asoils1 aDragone, Nicholas, B.1 aDiaz, Melisa, A.1 aHogg, Ian, D.1 aLyons, Berry1 aJackson, Andrew1 aWall, Diana, H.1 aAdams, Byron, J.1 aFierer, Noah  uhttps://agupubs.onlinelibrary.wiley.com/doi/abs/10.1029/2020JG00605202615nas a2200229   4500008004100000245011400041210006900155260001200224300001600236490000700252520188900259100002102148700002902169700002102198700002002219700002102239700002002260700001802280700001702298700001702315856005302332       2021                        eng d00aGeochemical zones and environmental gradients for soils from the central Transantarctic Mountains, Antarctica0 aGeochemical zones and environmental gradients for soils from the  c03/2021  a1629 - 16440 v183 a<p>Previous studies have established links between biodiversity and soil geochemistry in the McMurdo Dry Valleys, Antarctica, where environmental gradients are important determinants of soil biodiversity. However, these gradients are not well established in the central Transantarctic Mountains, which are thought to represent some of the least hospitable Antarctic soils. We analyzed 220 samples from 11 ice-free areas along the Shackleton Glacier (~85&deg;S), a major outlet glacier of the East Antarctic Ice Sheet. We established three zones of distinct geochemical gradients near the head of the glacier (upper), its central part (middle), and at the mouth (lower). The upper zone had the highest water-soluble salt concentrations with total salt concentrations exceeding 80 000 &micro;g g<sup>-1</sup>, while the lower zone had the lowest water-soluble N:P ratios, suggesting that, in addition to other parameters (such as proximity to water and/or ice), the lower zone likely represents the most favorable ecological habitats. Given the strong dependence of geochemistry on geographic parameters, we developed multiple linear regression and random forest models to predict soil geochemical trends given latitude, longitude, elevation, distance from the coast, distance from the glacier, and soil moisture (variables which can be inferred from remote measurements). Confidence in our random forest model predictions was moderately high with <i>R</i><sup>2</sup> values for total water-soluble salts, water-soluble N:P, ClO<sub>4</sub><sup>-</sup>, and ClO<sub>3</sub><sup>-</sup> of 0.81, 0.88, 0.78, and 0.74, respectively. These modeling results can be used to predict geochemical gradients and estimate salt concentrations for other Transantarctic Mountain soils, information that can ultimately be used to better predict distributions of soil biota in this remote region.</p>1 aDiaz, Melisa, A.1 aGardner, Christopher, B.1 aWelch, Susan, A.1 aJackson, Andrew1 aAdams, Byron, J.1 aWall, Diana, H.1 aHogg, Ian, D.1 aFierer, Noah1 aLyons, Berry  uhttps://bg.copernicus.org/articles/18/1629/2021/00621nas a2200181   4500008004100000245010500041210006900146260001200215300001200227490000700239100002000246700002400266700001900290700001700309700002100326700002100347856007100368       2012                        eng d00aPerchlorate and chlorate biogeochemistry in ice-covered lakes of the McMurdo Dry Valleys, Antarctica0 aPerchlorate and chlorate biogeochemistry in icecovered lakes of   c12/2012  a19 - 300 v981 aJackson, Andrew1 aDavila, Alfonso, F.1 aEstrada, Nubia1 aLyons, Berry1 aCoates, John, D.1 aPriscu, John, C.  uhttp://www.sciencedirect.com/science/article/pii/S001670371200511X