Soil carbon distribution and site characteristics in hyper-arid soils of the Atacama Desert: A site with Mars-like soils
Introduction
The Atacama Desert is located along the western coast of South America throughout the shore region of southern Peru and northern Chile covering about 3500 km, between 10°S to 35°S latitude, and 70°W to 72°W longitude. Because the average values of precipitation in the complete region are less than 200 mm/y, Houston and Hartley (2003) divided this desert according to the aridity index (AI) as semiarid (0.2 < P/PET < 0.5), arid (0.05 < P/PET < 0.2), and hyper-arid (P/PET < 0.05) regions (Fig. 1, Table 1, and Table 1S). This index was calculated as the ratio of precipitation and potential evapotranspiration (P/PET) using Thornthwaite’s equations as a function of mean monthly temperatures and mean monthly number of daylight hours (Thornwaite, 1948, UNEP, 1997). Hyper-arid areas emerge independent of human activities under a natural development and evolution of drier climates denominated “aridization”. This process takes place much more slowly than the processes of “desertification” (Kottek et al., 2006), which are defined as the land degradation in dry areas resulting from climatic variations and human activities (Houerou, 1996). Thus, hyper-arid lands are usually excluded from the consideration of desertification (Schlesinger, 1997). The combined effects of a high pressure system located on the western Pacific Ocean, the cold north-flowing Humboldt Current, and the rain shadow of the Andean Cordillera intercepting precipitation from the inter-tropical convergence are the main factors involved in the hyper-arid climate formation in this region (Arroyo et al., 1988, Houston and Hartley, 2003). These factors have been used in support of geological evidence that the Atacama Desert has remained hyper-arid between 9 and 25 Ma (Alpers and Brimhall, 1988, Dunai et al., 2005, Evenstar et al., 2005). Studies based on sedimentologic evidence estimate that the beginning of continuous hyper-aridity occurred until the Late Pliocene (Hartley and Chong, 2002, Hartley et al., 2005, Houston and Hartley, 2003), a conclusion supported by the end of supergene enrichment of copper deposits in the Atacama Desert (Arancibia and Matthews, 2006). However, this region seems to have had rainfall oscillations throughout its Quaternary history (Betancourt et al., 2000, Latorre et al., 2003). Currently, the mean values of mean annual precipitation recorded between 15°S and 27°S latitude are less than 100 mm/y, for this reason this particular area is considered one of the driest regions on the world (Dillon and Hoffmann, 1997, McKay et al., 2003), and is the object of our principal analysis in this study.
Soil carbon concentrations to a specified depth are needed for calculating current soil C stores (Feng et al., 2002, Kern, 1994, Schlesinger et al., 1990). A shift towards a greater area of arid land potentially represents a permanent loss in the productive capacity of the biosphere (Schlesinger et al., 1990). In addition, relating soil carbon to site characteristics may help in formulating and evaluating static and dynamic models of pedogenic processes (Burke et al., 1989), and in assessing the effect of land use and climate change on soil C stores (Bon, 1982, Feng et al., 2002, Grigal and Ohmann, 1992, Plante et al., 2006, Turner et al., 1993). In this context, few analyses have been made showing the relationship between soil carbon and environmental site characteristics for hyper-arid soils, and even for arid–semiarid regions. Indeed, although other authors have calculated the organic or inorganic carbon concentrations in samples of soils from the Atacama Desert (e.g. Navarro-González et al., 2003, Navarro-González et al., 2006, Ewing et al., 2006, Ewing et al., 2008, Lester et al., 2007), the importance of the total carbon distribution and its relationship with in situ characteristics have not been completely evaluated, perhaps due to the small number of samples used in those works (Ewing et al., 2008, Ewing et al., 2006).
The purpose of this study determines the surface and subsurface soil carbon concentration until one meter deep in the hyper-arid soils of the Atacama Desert in order (a) to evaluate the distribution and deposition of organic and inorganic forms of carbon present there, (b) to compare to arid and semiarid deposits in surrounding areas, (c) to analyze any relationship between carbon concentrations and some geomorphological and climatological variables “in situ”, and (d) to seek differences between the driest areas of Yungay and Pampas de La Joya located in Chile and Peru respectively, which have showed the lowest levels of organic carbon in previous studies (Ewing et al., 2008, Navarro-González et al., 2009, Navarro-González et al., 2006, Navarro-González et al., 2003, Valdivia-Silva, 2009b). Additionally, the predominant abiotic geochemical processes and eolic transportation observed in this region could be used as an excellent analogue in order to understand the carbon cycle present in other hyper-arid environments on Earth and/or Mars.
Section snippets
Site description
The Atacama Desert is located between 10°S and 35°S latitude in Peru and Chile, bounded on the east by the front ranges of the Andes and on the west by the Coast Range. Hyper-arid areas considered in this study were focused between 15°S and 27°S latitude because this encompasses the driest areas of the desert. Chilean and Peruvian areas, Yungay region and Pampas de La Joya respectively, present interesting geomorphological differences caused by variations on the tectonic uplift of the desert
Soil organic carbon (SOC)
Table 2 and Fig. 3 show the soil organic carbon concentrations in the surface and the first meter of depth from three different climatic regions in the Atacama Desert, respectively. For 485 samples of hyper-arid soils, SOC ranged from 1.8 μg C to 50.9 μg C per g of soil in the 0–0.1 m profile and from 1.8 μg C to 125.2 μg C per g of soil in the 0–1 m layer. Interestingly, the lowest values on surface SOC (2.14 ± 0.8 μg C) were found on the site named “Mar de Cuarzo”, located in the Peruvian region (16° 44′
Mars-like soils and perspectives
The role of the geochemical cycle of carbon into processes which have extremely limited amounts of water on Earth and Mars remain poorly studied and understood. The recent identification of calcium carbonate (∼3–5 wt.%) in the soils around the Phoenix landing site (Boynton et al., 2009) has increased interest in understanding these processes and has led, as the present study, to seek a better explanation of the carbon geochemistry on hyper-arid soils and environments considered analogues to the
Conclusions
The purpose of this study was to determine the surface and subsurface soil carbon concentration until one meter deep in the hyper-arid soils of the Atacama Desert in order (a) to evaluate the distribution and deposition of organic and inorganic forms of carbon present there, (b) to compare to arid and semiarid deposits in surrounding areas, (c) to analyze any relationship between carbon concentrations and some geomorphological and climatological variables “in situ”, and (d) to seek differences
Acknowledgments
Funding for this research comes from Grants from the Universidad Nacional Autónoma de México (DGAPA IN107107, IN109110), Consejo Nacional de Ciencia y Tecnología de México (CONACyT 45810-F, 98466, 121479), fellowship from NASA Postdoctoral Program, and by the National Aeronautics and Space Administration Astrobiology Science and Technology for Exploring Planets Program.
References (97)
- et al.
Advective, orographic and radiation fog in the Tarapacá region, Chile
Atmos. Res.
(2002) - et al.
Chemistry and mineralogy of outcrops at Meridiani Planum
Earth Planet. Sci. Lett.
(2005) - et al.
Rain infiltration and crust formation in the extreme arid zone of the Atacama Desert, Chile
Planet. Space Sci.
(2010) - et al.
Infrared imaging spectroscopy of Mars: H2O mapping and determination of CO2 isotopic ratios
Icarus
(2005) - et al.
A threshold in soil formation at Earth’s arid-hyperarid transition
Geochim. Cosmochim. Acta
(2006) - et al.
Phosphourus content in five representative landscapes units of the Lomas de Arequipa (Atacama Desert-Peru)
Catena
(2006) - et al.
Soil carbon in desertified land in relation to site characteristics
Geoderma
(2002) - et al.
Variability of organic material in surface horizons of the hyper-arid mars-like soils of the Atacama Desert
Adv. Space Res.
(2012) - et al.
Microflora of extreme arid Atacama Desert soils
Soil Biol. Biochem.
(2007) - et al.
The Mars Oxidant experiment (MOx) for Mars ‘96
Planet. Space Sci.
(1998)
High-frequency rock temperature data from hyper-arid desert environments in the Atacama and the Antarctic Dry Valleys and implications for rock weathering
Geomorphology
Long term atmospheric deposition as the source of nitrate and other salts in the Atacama desert, Chile: new evidence from mass-independent oxygen isotopic compositions
Geochemica et Cosmochemica Acta
Remnants of a fossil alluvial fan landscape of Miocene age in the Atacama Desert of northern chile using cosmogenic nuclide exposure age dating
Earth Planet. Sci. Lett.
Isotopic evidence for the source of Ca and S in soil gypsum, anhydrite and calcite in the Atacama Desert, Chile
Geochim. Cosmochim. Acta
Soil organic matter dynamics in paired rangeland and cropland topo-sequences in North Dakota
Geoderma
Thermally evolved gas analysis (TEGA) of hyperarid soils doped with microorganisms from the Atacama Desert in southern Peru: implications for the Phoenix mission
Adv. Space Res.
Multidisciplinary approach of the hyperarid desert of Pampas de La Joya in southern Peru as a new Mars-like soil analogue
Geochim. Cosmochim. Acta
Decomposition of Sodium formate and L- and D- alanine in the Pampas de La Joya soils: Implications as a new geochemical analogue to Martian regolith
Adv. Space Res.
The chemical-reactivity of the Martian soil and implications for future missions
Icarus
Middle Miocene climatic change in the Atacama Desert, northern Chile: evidence from supergene mineralization at La Escondida
Geol. Soc. Am. Bull.
The carbon budget in soils
Annual Rev Earth Planetary Sci.
Pedogenic evidence for climate change and aridification on Mars
Geochim. Cosmochim. Acta
The climatic and biotic thresholds on soil elemental cycling along an arid and to hyperarid rainfall gradient
Geochim. Cosmochim. Acta
K–Ar and 40Ar/39Ar geochronology of supergene processes in the Atacama Desert, Northern Chile: tectonic and climatic relations
J. Geol. Soc.
Effects of aridity on plant diversity in the northern Chilean Andes: results of a natural experiment
Ann. Mo. Bot. Garden
Oxidant enhancement in martian dust devils and storms: implications for life and habitability
Astrobiology
A 22,000-year record of monsoonal precipitation from northern Chile’s Atacama Desert
Science
Implications and limitations of the findings of the Viking Organic-analysis experiment
J. Mol. Evol.
On the ability of the Viking gas chromatography–mass spectrometer to detect organic matter
Proc. Natl. Acad. Sci. USA
Estimate of organic carbon in world soils (II)
Soil Sci. Soc. Am. J.
Evidence for calcium carbonate at the Mars phoenix landing site
Science
Texture, climate, and cultivation effects on soil organic matter content in US grassland soils
Soil Sci. Soc. Am. J.
Origin and distribution of soil organic matter in Taylor Valley, Antarctica
Ecology
Organic carbon cycling in Taylor Valley, Antarctica: quantifying soil reservoirs and soil respiration
Global Change Biol.
Carbon Dioxide Equilibria and Their Applications
Lomas formations of the Atacama Desert, northern Chile
Bacterial community structure in the hyperarid core of the Atacama Desert, Chile
Appl. Environ. Microbiol.
Oligocene-Miocene age of aridity in the Atacama Desert revealed by exposure dating of erosion-sensitive landforms
Geology
Chemometrix in Environmental Analysis
Geology and Origin of the Chilean Nitrate Deposits, Geological Society Professional Paper 1188
The Chilean nitrate deposits
Am. Sci
Determination of low bacterial concentrations in hyper-arid Atacama soils: comparison of biochemical and microscopy methods with real-time Quantitative-PCR
Can. J. Microbiol.
The delivery of organic matter from asteroids and comets to the early surface of Mars
Earth Moon Planet.
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