Papers by Stephanie Ewing
Soil Science Society of America Journal, 2007
Journal of Geophysical Research, 2006
Global Biogeochemical Cycles, 2007
In most climates on Earth, biological processes control soil N. In the Atacama Desert of Chile, a... more In most climates on Earth, biological processes control soil N. In the Atacama Desert of Chile, aridity severely limits biology, and soils accumulate atmospheric NO3−. We examined this apparent transformation of the soil N cycle using a series of ancient Atacama Desert soils (>2 My) that vary in rainfall (21 to <2 mm yr−1). With decreasing rainfall, soil organic C decreases to 0.3 kg C m−2 and biological activity becomes minimal, while soil NO3− and organic N increase to 4 kg N m−2 and 1.4 kg N m−2, respectively. Atmospheric NO3− (Δ17O = 23.0‰) increases from 39% to 80% of total soil NO3− as rainfall decreases. These soils capture the transition from a steady state, biologically mediated soil N cycle to a dominantly abiotic, transient state of slowly accumulating atmospheric N. This transition suggests that oxidized soil N may be present in an even more arid and abiotic environment: Mars.
Geological Society of America Bulletin, 2012
Geochimica et Cosmochimica Acta, 2008
Geochimica et Cosmochimica Acta, 2012
Environmental Science & Technology, 2010
Hypolithic autotrophs inhabit translucent rocks in the world`&#39;s most extreme hot and cold... more Hypolithic autotrophs inhabit translucent rocks in the world`&#39;s most extreme hot and cold deserts. Across a rainfall gradient in the Atacama, we measured a three-fold decline in the molecular diversity of cyanobacterial communities and a drop in their abundance from 28% in relatively wet sites to 0.08% in the driest core. Like plants, hypoliths appear to exhibit traits of self-organized
Geochimica et Cosmochimica Acta, 2006
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Papers by Stephanie Ewing