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GLOBAL BIOGEOCHEMICAL CYCLES,
VOL. 21,
GB3009,
doi:10.1029/2006GB002838,
2007
Rainfall limit of the N cycle on Earth
Stephanie A. Ewing
Division of Ecosystem Sciences, Department of Environmental Science Policy and Management, University of California, Berkeley,
California, USA
Greg Michalski
Department of Earth and Atmospheric Sciences, Purdue University, West Lafayette, Indiana, USA
Mark Thiemens
Division of Physical Sciences, University of California, San Diego, La Jolla, California, USA
Richard C. Quinn
SETI Institute, NASA Ames Research Center, Moffett Field, California, USA
Jennifer L. Macalady
Penn State Astrobiology Research Center, Department of Geosciences, Pennsylvania State University, University Park, Pennsylvania,
USA
Steven Kohl
Division of Atmospheric Sciences, Desert Research Institute, Reno, Nevada, USA
Scott D. Wankel
U.S. Geological Survey, Menlo Park, California, USA
Carol Kendall
U.S. Geological Survey, Menlo Park, California, USA
Christopher P. McKay
NASA-Ames Research Center, Moffett Field, California, USA
Ronald Amundson
Division of Ecosystem Sciences, Department of Environmental Science Policy and Management, University of California, Berkeley,
California, USA
Abstract
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.
Received 9
September
2006;
accepted 23
May
2007;
published 8
August
2007.
Index Terms: 0469 Biogeosciences: Nitrogen cycling; 0428 Biogeosciences: Carbon cycling (4806); 0454 Biogeosciences: Isotopic composition and chemistry (1041, 4870); 0486 Biogeosciences: Soils/pedology (1865).
Read Full Article (file size: 498335 bytes) Cited by
Citation: Ewing, S. A., G. Michalski, M. Thiemens, R. C. Quinn, J. L. Macalady, S. Kohl, S. D. Wankel, C. Kendall, C. P. McKay, and R. Amundson
(2007),
Rainfall limit of the N cycle on Earth,
Global Biogeochem. Cycles,
21,
GB3009,
doi:10.1029/2006GB002838.
Copyright 2007 by the American Geophysical Union.
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