Multidisciplinary approach of the hyperarid desert of Pampas de La Joya in southern Peru as a new Mars-like soil analog     

Julio E. Valdivia-Silva  Rafael Navarro-González  Lauren E. Fletcher  Reneé Condori-Apaza 《Geochimica et cosmochimica acta》2011,75(7):1975-1991

The distribution of living organisms, organic matter, and chemical properties in Mars-like environments on Earth can be used as a model to guide the investigation of possible habitable environments on Mars. This work aims to demonstrate that the place known informally as the “Mar de Cuarzo” (Sea of Quartz) in the Pampas de La Joya desert southern Peru (between 16°S and 17°S latitude), contains soils with characteristics similar to those found on the Martian surface. Using a multidisciplinary approach, we studied the environmental data, geology, organic matter content, oxidant activity, and microbiology of this area. Our data show that (1) Mar de Cuarzo is a hyper arid area with a lower concentration of organic matter than those found in the Mars-like soils from Yungay area (Atacama Desert in Chile), while at the same time having, comparable extreme environmental conditions, and very low levels of microorganisms. (2) The detrital components of the soils come essentially from the Andean volcanic chain and local outcrops of Precambrian gneisses and Cretaceous granitic batholiths. (3) The presence of microclimates, geomorphological features, and the high influence of the “El Niño Southern Oscillation (ENSO)” allowed the formation of exotic and heterogeneous chemical deposits in these soils, including iron oxides, sulfates, and other evaporites. (4) Thermal volatilization in these soils (using methods similar to the Viking and Phoenix instruments) shows high oxidant activity. (5) Labeled release experiment (similar to the Viking instrument) shows high degradation of nutrients added in these soils.Altogether, the Mar de Cuarzo area in the Pampas de La Joya is an interesting place for astrobiological studies as a new analog to Mars, and for comparative analyses with other hyperarid analogs as Yungay.  相似文献   

Origin of rare earth element anomalies in mangrove sediments,Sepetiba Bay,SE Brazil: used as geochemical tracers of sediment sources     

Emmanoel V. Silva-Filho  Christian J. Sanders  Michel Bernat  Ana M. G. Figueiredo  Silvia M. Sella  Julio Wasserman 《Environmental Earth Sciences》2011,64(5):1257-1267

Elemental contents were determined in two mangrove habitats along Sepetiba Bay, SE Brazil, an area impacted by local industrial activities, as well as hinterland water diversion networks. This study demonstrates how specific REEs (La, Ce, Nd, Sm, Eu, Tb, Yb and Lu) may be used as a sediment source tracer to mangrove-dominated coastlines. From the two stations studied, a pair of cores was collected, one in the mangrove forest and the other in the tidal flat. Station 1 results show a general enrichment in most of the fractioned patterns of the REEs normalised by Post-Archean Australian Shale. The relatively light rare earth elements are similarly enriched in the generally more polluted Station 1. Despite the probable difference in background sediment characteristics, a common sharp increase in mud contents patterns in the upper part of the mangrove sediment core was related to a lower REE content as well as Eu anomalies. With existing knowledge of clockwise water circulation in the bay, these patterns can be explained by man-made water diversion from the São Francisco and Guandu rivers, initiated more than 30 years ago, whereby suspended matter with relatively large contents of REEs and material originating from industrial sources accumulate in the eastern sector of the bay. This is the first comprehensive assessment of REEs as sedimentary tracers in a mangrove ecosystem in Brazil.  相似文献   

Hiding cusps in cores: kinematics of disc galaxies in triaxial dark matter haloes     

Eric Hayashi  Julio F. Navarro † 《Monthly notices of the Royal Astronomical Society》2006,373(3):1117-1124

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The population of faint Jupiter family comets near the Earth     

Julio A. Fernández  Alessandro Morbidelli 《Icarus》2006,185(1):211-222

We study the population of faint Jupiter family comets (JFCs) that approach the Earth (perihelion distances q<1.3 AU) by applying a debiasing technique to the observed sample. We found for the debiased cumulative luminosity function (CLF) of absolute total magnitudes H₁₀ a bimodal distribution in which brighter comets (H₁₀?9) follow a linear relation with a steep slope α=0.65±0.14, while fainter comets follow a much shallower slope α=0.25±0.06 down to H₁₀∼18. The slope can be pushed up to α=0.35±0.09 if a second break in the H₁₀ distribution to a much shallower slope is introduced at H₁₀∼16. We estimate a population of about 10³ faint JFCs with q<1.3 AU and 10<H₁₀<15 (radii ∼0.1-0.5 km). The shallowness of the CLF for faint near-Earth JFCs may be explained either as: (i) the source population (the scattered disk) has an equally very shallow distribution in the considered size range, or (ii) the distribution is flattened by the disintegration of small objects before that they have a chance of being observed. The fact that the slope of the magnitude distribution of the faint active JFCs is very similar to that found for a sample of dormant JFCs candidates suggests that for a surviving (i.e., not disintegrated) object, the probability of becoming dormant versus keeping some activity is roughly size independent.  相似文献   

Petrology,phase equilibria modelling,noble gas chronology and thermal constraints of the El Pozo L5 meteorite     

Pedro Corona-Chávez  María del Sol Hernández-Bernal  Pietro Vignola  Rufino Lozano-Santacruz  Juan Julio Morales-Contreras  Margarita Reyes-Salas  Jesús Solé-Viñas  José F. Molina 《Chemie der Erde / Geochemistry》2018,78(2):248-253

We present the results of physical properties, petrography, bulk chemistry, mineral compositions, phase relations modelling and Noble gases study of the meteorite El Pozo. The petrography and mineral compositions indicate that the meteorite is an L5 chondrite with a low shock stage of S2-S3. Heterogenous weathering was preferentially along shock structures. Thermobarometric calculations indicate thermal equilibrium conditions between 768?°C and 925?°C at ～4 to 6?kb, which are substantially consistent with the petrological metamorphism type 5. A pseudosection phase diagram is relatively consistent with the mineral assemblage observed and PT conditions calculated. Temperature vs. fO₂ diagram shows that plagioclase compositional stability is very sensitive to Tschermack substitution in orthopyroxene, clinopyroxene and X_An plagioclase during the high temperature metamorphic process. Based on noble gases He, Ne, Ar and K contents a cosmogenic exposure age CRE of 1.9?Myr was calculated. The ²¹Ne would be totally cosmogenic, with no primordial Ne. The ²¹Ne/²²Ne value (0.97) is higher than solar value. According to the cosmogenic Ne content, we argue that El Pozo chondrite originally had a pre-atmospheric mass of 9–10?kg, which would have been produced by a later collision after the recognized collision of the L-chondrite parent body ～470?Ma ago.  相似文献   

Multi-approach assessment of the spatial distribution of the specific yield: application to the Crau plain aquifer,France     

Seraphin  Pierre  Gonçalvès  Julio  Vallet-Coulomb  Christine  Champollion  Cédric 《Hydrogeology Journal》2018,26(4):1221-1238

Spatially distributed values of the specific yield, a fundamental parameter for transient groundwater mass balance calculations, were obtained by means of three independent methods for the Crau plain, France. In contrast to its traditional use to assess recharge based on a given specific yield, the water-table fluctuation (WTF) method, applied using major recharging events, gave a first set of reference values. Then, large infiltration processes recorded by monitored boreholes and caused by major precipitation events were interpreted in terms of specific yield by means of a one-dimensional vertical numerical model solving Richards’ equations within the unsaturated zone. Finally, two gravity field campaigns, at low and high piezometric levels, were carried out to assess the groundwater mass variation and thus alternative specific yield values. The range obtained by the WTF method for this aquifer made of alluvial detrital material was 2.9– 26%, in line with the scarce data available so far. The average spatial value of specific yield by the WTF method (9.1%) is consistent with the aquifer scale value from the hydro-gravimetric approach. In this investigation, an estimate of the hitherto unknown spatial distribution of the specific yield over the Crau plain was obtained using the most reliable method (the WTF method). A groundwater mass balance calculation over the domain using this distribution yielded similar results to an independent quantification based on a stable isotope-mixing model. This agreement reinforces the relevance of such estimates, which can be used to build a more accurate transient hydrogeological model.

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Seismic scenario including site-effect determination in Torreperogil and Sabiote,Jaén (Spain), after the 2013 earthquake sequence   总被引：1，自引：1，他引：0  

Juan Rueda  Julio Mezcua  Rosa M. García Blanco  Alberto Núñez  María Fernández de Villalta 《Natural Hazards》2015,79(2):675-697

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Rock-magnetic properties of topsoils and urban dust from Morelia (>800,000 inhabitants), Mexico: Implications for anthropogenic pollution monitoring in Mexico’s medium size cities     

Bertha Aguilar Reyes  Francisco Bautista  Avto Goguitchaichvili  Juan Julio Morales Contreras  Julie Battu  Patricia Quintana Owen  Claire Carvallo 《Geofísica Internacional》2013,52(2):121-133

In this work, we investigate the correlation between some magnetic parameters and the level of contamination by heavy metals in urban soils from Morelia city, western Mexico. The magnetic study was carried out on 98 urban soils samples belonging to distinct land uses. Most of analyzed samples contain ferrimagnetic minerals as the responsible for magnetization, most probably corresponding to the titanomagnetites/ titanomaghemites solid solutions. This is inferred from the susceptibility vs. temperature measurements and the isothermal remanent magnetization (IRM) experiments. These measurements also indicate that most of samples are almost completely saturated before 300 mT. Additionally, the S_-200 values (S_-200 = IRM_-200/ SIRM, where IRM_-200= Back-field of 200 mT after magnetic saturation) are between 0.7 and 1.0, characteristic of low coercivity magnetic minerals. The averaged saturation isothermal remanent magnetization (SIRM) curves can be used as an indicator of pollution level, as these curves show different saturation values according to the level of contamination by heavy metals: Cu, Ni, Cr and Sr. These associations of (titano)magnetite with heavy metals were observed by Scanning Electron Microscope revealing some complex aggregates rather than commonly detected spherules.  相似文献   

Implications of pore space characteristics on diffusive transport in basalts and granites     

Stefan Dultz  Anna V. Simonyan  Julio Pastrana  Harald Behrens  Michael Plötze  Thomas Rath 《Environmental Earth Sciences》2013,69(3):969-985

A detailed characterization of the pore space is crucial for understanding of transport and element transfer in rocks. Here, the effect of differences in texture and content of secondary minerals on transport in pore systems was determined for two rocks of widespread occurrence, mid-ocean ridge basalts (MORB) and granites. Pore space characteristics were analyzed by Hg-porosimetry, intrusion of a molten alloy, and synchrotron-based X-ray tomographic microscopy. For evaluating the role of pore space characteristics for the prediction of diffusive transport, data on porosity, and the effective diffusion coefficient (D _eff) were compared. Extended connective pore systems due to cracks and mineral dissolution are present in samples of both rocks, indicating high internal specific surface area. Uneven pore size distributions in altered MORB samples can be assigned to secondary minerals. Pore spaces determined by X-ray tomography, used to determine main direction of pores in the 3-D orthogonal system, suggest a slight anisotropy. In log–log plots, both rocks show roughly a linear dependence of D _eff for H₂O and compounds with comparable diffusivities (D₂O, monovalent cations, and anions) on porosity, but at same porosity D _eff is clearly higher in granitic than in basaltic samples. This difference is increasing with decreasing porosity, indicating that at low porosities the efficiency of element transport in basaltic samples is diminished, mainly inherited by the presence of small pores slowing down diffusion. The fact that diffusive transport in basaltic rocks is stronger dependent on porosity than in granitic rocks shows that also other rock characteristics such as pore size distribution and tortuosity of the pore network, highly affected by the alteration degree, can markedly affect transport and reactivity of pore solution.  相似文献   

Airports and Environment: Proposal of Wastewater Reclamation at São Paulo International Airport     

Elaine Nolasco Ribeiro  Wilson Cabral de Sousa Jr  Marcelo de Julio  Wilfredo Urruchi Irrazabal  Marcelo Antunes Nolasco 《洁净——土壤、空气、水》2013,41(7):627-634

One way to reduce water consumption in urban areas is by using alternative sources of supply that can be provided by collecting rainwater and reusing wastewater for less restricted purposes. Thus, this study evaluated the characteristics of effluents produced by the wastewater treatment plant (WWTP) of São Paulo International Airport (SPIA), Brazil, in order to reuse it in non‐potable situations. The results achieved, indicated high efficiency in the biological system utilized by SPIA. The removal rates is equal to or >90% for most of the parameters analyzed, among them, fluoride, salinity, nitrite, nitrate, ammonium nitrogen, total nitrogen, phosphorus, sedimentable solids, turbidity, conductivity, apparent color, chemical oxygen demand, biochemical oxygen demand, total organic carbon, fecal coliforms, and oils and greases. Despite the final effluents were good enough to be launched in the local streams, they shall be submitted to a complementary treatment in order to fit some quality parameters to be reused for specific demands (landscape irrigation, toilet flushing, vehicle washing, fire fighting, and dust control).  相似文献