Geochemical, isotopic, and mineralogical constraints on atmospheric deposition in the hyper-arid Atacama Desert, Chile

Fan, Wenjie; Michalski, Greg; Seo, Jungyun; Wen-sheng, GE

doi:10.1016/j.gca.2014.03.017

Cited by 41 publications

(47 citation statements)

References 119 publications

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“…XRD of the clay-size fraction also demonstrated the presence of discrete illite and chlorite. Samples collected from the wet clay-bearing layers also contain halite (NaCl), gypsum (CaSO 4 •2H 2 O), calcium carbonate (calcite, CaCO 3 ), albite (Na(AlSi 3 O 8 )) and quartz (SiO 2 ) (Supplemental Figure S1), all minerals typical of surface soils in this area [39][40][41] .…”

Section: Resultsmentioning

confidence: 99%

Inhabited subsurface wet smectites in the hyperarid core of the Atacama Desert as an analog for the search for life on Mars

Azua‐Bustos

Fairén

González-Silva

et al. 2020

Sci Rep

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The modern Martian surface is unlikely to be habitable due to its extreme aridity among other environmental factors. This is the reason why the hyperarid core of the Atacama Desert has been studied as an analog for the habitability of Mars for more than 50 years. Here we report a layer enriched in smectites located just 30 cm below the surface of the hyperarid core of the Atacama. We discovered the clay-rich layer to be wet (a phenomenon never observed before in this region), keeping a high and constant relative humidity of 78% (aw 0.780), and completely isolated from the changing and extremely dry subaerial conditions characteristic of the Atacama. The smectite-rich layer is inhabited by at least 30 halophilic species of metabolically active bacteria and archaea, unveiling a previously unreported habitat for microbial life under the surface of the driest place on Earth. The discovery of a diverse microbial community in smectite-rich subsurface layers in the hyperarid core of the Atacama, and the collection of biosignatures we have identified within the clays, suggest that similar shallow clay deposits on Mars may contain biosignatures easily reachable by current rovers and landers.

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Section: Resultsmentioning

confidence: 99%

Inhabited subsurface wet smectites in the hyperarid core of the Atacama Desert as an analog for the search for life on Mars

Azua‐Bustos

Fairén

González-Silva

et al. 2020

Sci Rep

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“…The model parameterization for heterogeneous uptake of NO 2 has significant impacts on HONO and oxidants (OH and ozone) in the model. HONO production from this reaction has been suggested to be an important source of OH in Chinese haze due to high NO x and aerosol abundances (Hendrick et al, 2014;Tong et al, 2016;Wang et al, 2017), with implications for the gas-phase formation of sulfate aerosol from the oxidation of sulfur dioxide by OH (Shao et al, 2019;Li et al, 2018b). More recent laboratory studies suggest that the reaction probability of NO 2 on aerosols is lower than that previously used in the model.…”

Section: B Alexander Et Al: Global Inorganic Nitrate Isotopesmentioning

confidence: 99%

Global inorganic nitrate production mechanisms: comparison of a global model with nitrate isotope observations

et al. 2020

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Abstract. The formation of inorganic nitrate is the main sink for nitrogen oxides (NOx = NO + NO2). Due to the importance of NOx for the formation of tropospheric oxidants such as the hydroxyl radical (OH) and ozone, understanding the mechanisms and rates of nitrate formation is paramount for our ability to predict the atmospheric lifetimes of most reduced trace gases in the atmosphere. The oxygen isotopic composition of nitrate (Δ17O(nitrate)) is determined by the relative importance of NOx sinks and thus can provide an observational constraint for NOx chemistry. Until recently, the ability to utilize Δ17O(nitrate) observations for this purpose was hindered by our lack of knowledge about the oxygen isotopic composition of ozone (Δ17O(O3)). Recent and spatially widespread observations of Δ17O(O3) motivate an updated comparison of modeled and observed Δ17O(nitrate) and a reassessment of modeled nitrate formation pathways. Model updates based on recent laboratory studies of heterogeneous reactions render dinitrogen pentoxide (N2O5) hydrolysis as important as NO2 + OH (both 41 %) for global inorganic nitrate production near the surface (below 1 km altitude). All other nitrate production mechanisms individually represent less than 6 % of global nitrate production near the surface but can be dominant locally. Updated reaction rates for aerosol uptake of NO2 result in significant reduction of nitrate and nitrous acid (HONO) formed through this pathway in the model and render NO2 hydrolysis a negligible pathway for nitrate formation globally. Although photolysis of aerosol nitrate may have implications for NOx, HONO, and oxidant abundances, it does not significantly impact the relative importance of nitrate formation pathways. Modeled Δ17O(nitrate) (28.6±4.5 ‰) compares well with the average of a global compilation of observations (27.6±5.0 ‰) when assuming Δ17O(O3) = 26 ‰, giving confidence in the model's representation of the relative importance of ozone versus HOx (= OH + HO2 + RO2) in NOx cycling and nitrate formation on the global scale.

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“…The modulation of annual Δ 17 O NO3atm values by long-term accumulation is exemplified in recent analysis of dust collected for 2.5 years along an east-west transect in the Atacama (Wang et al, 2014). The  17 O values of NO 3 extracted from the seven dust collectors located in the hyper-arid core (~160 km wide) were relatively consistent of 25.8±0.5‰ (Wang et al, 2014), in contrast to the annual Δ 17 O NO3atm variations of ~10‰ for an Andean ice core (Buffen et al, 2014). For its secular variations, the 30-year running average of the Δ 17 O NO3atm values for the Site A, Greenland ice core during 1680-1830 only showed a 2.5‰ variation, with the high values mainly owing to an elevation of O 3 and decrease of •OH in the atmosphere induced by the intense biomass burning recorded in North America (Alexander et al, 2004).…”

Section: No 3 Concentrations and Isotopic Signaturesmentioning

confidence: 94%

“…Temporal variations of Δ 17 O NO3atm also cannot be significant for using the MAP-Δ 17 O NO3soil proxy because these variations would average out over the NO 3 accumulation timescales (100-1000 yrs) (Walvoord et al, 2003;Michalski et al, 2004). The modulation of annual Δ 17 O NO3atm values by long-term accumulation is exemplified in recent analysis of dust collected for 2.5 years along an east-west transect in the Atacama (Wang et al, 2014). The  17 O values of NO 3 extracted from the seven dust collectors located in the hyper-arid core (~160 km wide) were relatively consistent of 25.8±0.5‰ (Wang et al, 2014), in contrast to the annual Δ 17 O NO3atm variations of ~10‰ for an Andean ice core (Buffen et al, 2014).…”

Section: No 3 Concentrations and Isotopic Signaturesmentioning

confidence: 99%

Oxygen-17 anomaly in soil nitrate: A new precipitation proxy for desert landscapes

Wang

Wen-sheng

Luo

et al. 2016

Earth and Planetary Science Letters

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The nitrogen cycle in desert soil ecosystems is particularly sensitive to changes in precipitation, even of relatively small magnitude and short duration, because it is already under water stress. This suggests that desert soils may have preserved past evidence of small variations in continental precipitation. We have measured nitrate (NO 3-) concentrations in soils from the Atacama (Chile), Kumtag (China), Mojave (US), and Thar (India) deserts, and stable nitrogen and oxygen isotope (15 N, 17 O, and 18 O) abundances of the soil NO 3-. 17 O anomalies (Δ 17 O), the deviations from the mass-independent isotopic fractionation, were detected in soil NO 3 from almost all sites of these four deserts. There was a strong negative correlation between the mean annual precipitation (MAP) and soil NO 3-Δ 17 O values (Δ 17 O NO3soil). This MAP-Δ 17 O NO3soil correlation advocated Δ 17 O NO3soil as a new precipitation proxy and was then used to assess precipitation changes in southwestern US at the Pliocene-Pleistocene boundary, in South America during the Miocene, and the Sahara Desert in the past 10 kyr using NO 3-Δ 17 O in paleosols or ancient aquifers. Global and the US maps of surface Δ 17 O NO3soil were also projected with available MAP datasets based on the MAP-Δ 17 O NO3soil model.

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Geochemical, isotopic, and mineralogical constraints on atmospheric deposition in the hyper-arid Atacama Desert, Chile

Cited by 41 publications

References 119 publications

Inhabited subsurface wet smectites in the hyperarid core of the Atacama Desert as an analog for the search for life on Mars

Inhabited subsurface wet smectites in the hyperarid core of the Atacama Desert as an analog for the search for life on Mars

Global inorganic nitrate production mechanisms: comparison of a global model with nitrate isotope observations

Oxygen-17 anomaly in soil nitrate: A new precipitation proxy for desert landscapes

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