Fernando Rull

Determination of Chlorinity in Aqueous Fluids Using Raman Spectroscopy of the Stretching Band of Water at Room Temperature: Application to Fluid Inclusions

A new analytical method, based on the Raman spectroscopy of the ν(OH) stretching vibration of water, has been developed for the determination of the concentration of chloride in aqueous solutions with the goal of reconstructing the bulk ion content of fluid inclusions that are relics of paleo-fluid circulation in rocks. The method involves calibrating the area of one band of the spectrum difference between pure water and solutions of appropriate composition with respect to the chloride concentration. Calibration curves were constructed for the major geological chemical salts LiCl, NaCl, KCl, CaCl2, and MgCl2, and NaCl–CaCl2 systems. The application to fluid inclusions has been confirmed using synthetic fluid inclusions. For cubic minerals such as fluorite, the calibration curve for the NaCl system correctly estimates the chlorinity. For birefringent minerals, such as quartz, the Raman spectrum of the aqueous solution depends on the orientation of the host crystal. The crystal must be oriented in such a way that one axis of the ellipse of the indicatrix projects parallel to the spectrometer slit. This method complements micro-thermometric data and allows the determination of chlorinity when ice-melting temperature cannot be used.

FT-RAMAN SPECTROSCOPY OF GUMS OF TECHNOLOGICAL SIGNIFICANCE

Abstract The FT-Raman spectra of four technically important gums, namely, locust bean gum, karaya gum (five varieties), gum tragacanth (nine varieties) and gum ghatti (four varieties), are reported. Bands characteristic of each gum which can be used for their identification are identified and assigned to molecular species where possible. Because the gums contain similar chemical components, an integral part of the current study has been self-deconvolution of the Raman spectra. The spectra provide the first examples of a database for gums using a nondestructive analytical technique.

The 2005 MARTE Robotic Drilling Experiment in Río Tinto, Spain: Objectives, Approach, and Results of a Simulated Mission to Search for Life in the Martian Subsurface

The Mars Astrobiology Research and Technology Experiment (MARTE) simulated a robotic drilling mission to search for subsurface life on Mars. The drill site was on Peña de Hierro near the headwaters of the Río Tinto river (southwest Spain), on a deposit that includes massive sulfides and their gossanized remains that resemble some iron and sulfur minerals found on Mars. The mission used a fluidless, 10-axis, autonomous coring drill mounted on a simulated lander. Cores were faced; then instruments collected color wide-angle context images, color microscopic images, visible-near infrared point spectra, and (lower resolution) visible-near infrared hyperspectral images. Cores were then stored for further processing or ejected. A borehole inspection system collected panoramic imaging and Raman spectra of borehole walls. Life detection was performed on full cores with an adenosine triphosphate luciferin-luciferase bioluminescence assay and on crushed core sections with SOLID2, an antibody array-based instrument. Two remotely located science teams analyzed the remote sensing data and chose subsample locations. In 30 days of operation, the drill penetrated to 6 m and collected 21 cores. Biosignatures were detected in 12 of 15 samples analyzed by SOLID2. Science teams correctly interpreted the nature of the deposits drilled as compared to the ground truth. This experiment shows that drilling to search for subsurface life on Mars is technically feasible and scientifically rewarding.

Novel spectroscopic deconvolution procedure for complex biological systems: vibrational components in the FT-Raman spectra of ice-man and contemporary skin

Skin samples from the corpse of a late-Neolithic man (5200 years BC) found in a glacier in Oetzal, commonly known as the Ice-man, have been analysed using FT-Raman spectroscopy. Good quality spectra have been obtained and compared with those from contemporary freeze-dried stratum corneum, using a time-dependent FT deconvolution method. This provided vibrational spectroscopic information about unresolved or partially resolved features including band halfwidth data, which are particularly useful for identifying membrane order–disorder variations between ancient and modern tissues. At the molecular level, the majority of the vibrational modes present in contemporary tissue were also evident in the spectra of the ancient skin, although Ice-man skin differed from modern skin in the ν(C—H) stretching region, attributable to the oxidation of alkenic bonds. Additionally, some degradation of the protein components (i.e. keratin) was indicated by the reduction in vibrational intensity of the amide I[ν(C—O)] and amide III [ν(C—N) and δ(N—H)] modes.

Habitability on Early Mars and the Search for Biosignatures with the ExoMars Rover

Abstract The second ExoMars mission will be launched in 2020 to target an ancient location interpreted to have strong potential for past habitability and for preserving physical and chemical biosignatures (as well as abiotic/prebiotic organics). The mission will deliver a lander with instruments for atmospheric and geophysical investigations and a rover tasked with searching for signs of extinct life. The ExoMars rover will be equipped with a drill to collect material from outcrops and at depth down to 2 m. This subsurface sampling capability will provide the best chance yet to gain access to chemical biosignatures. Using the powerful Pasteur payload instruments, the ExoMars science team will conduct a holistic search for traces of life and seek corroborating geological context information. Key Words: Biosignatures—ExoMars—Landing sites—Mars rover—Search for life. Astrobiology 17, 471–510.

AstRoMap European Astrobiology Roadmap

Abstract The European AstRoMap project (supported by the European Commission Seventh Framework Programme) surveyed the state of the art of astrobiology in Europe and beyond and produced the first European roadmap for astrobiology research. In the context of this roadmap, astrobiology is understood as the study of the origin, evolution, and distribution of life in the context of cosmic evolution; this includes habitability in the Solar System and beyond. The AstRoMap Roadmap identifies five research topics, specifies several key scientific objectives for each topic, and suggests ways to achieve all the objectives. The five AstRoMap Research Topics are • Research Topic 1: Origin and Evolution of Planetary Systems • Research Topic 2: Origins of Organic Compounds in Space • Research Topic 3: Rock-Water-Carbon Interactions, Organic Synthesis on Earth, and Steps to Life • Research Topic 4: Life and Habitability • Research Topic 5: Biosignatures as Facilitating Life Detection It is strongly recommended that steps be taken towards the definition and implementation of a European Astrobiology Platform (or Institute) to streamline and optimize the scientific return by using a coordinated infrastructure and funding system. Key Words: Astrobiology roadmap—Europe—Origin and evolution of life—Habitability—Life detection—Life in extreme environments. Astrobiology 16, 201–243.

RAMAN SPECTRAL STUDIES ON IONIC INTERACTION IN AQUEOUS ALKALI SULFATE SOLUTIONS

Abstract Raman spectra were measured for aqueous solutions of alkali sulfates, Li 2 SO 4 , Na 2 SO 4 , K 2 SO 4 , Rb 2 SO 4 and Cs 2 SO 4 at various concentrations and at room temperature. The changes in the band parameters and are in the band profiles of the ν 1 (SO 4 2− ) mode were studied as a function of the salt concentration. The band maximum ν max shifts almost linearly with concentration for all the salts. The slope of the lines plotted ν max vs. concentration decreases in the order of Li + > Na + > K + > Rb + > Cs + , and the former two have positive slope, while the last two have a negative one. For the case of K + the line is almost horizontal. The intercept of the lines converges to a single point of 980.8 ± 0.2 cm −1 . The width measured at the half height and the integrated band width given by β = A I(ν max ) , where A denotes the integrated area of the band and I ( ν max ) the intensity at the band maximum, increased with concentration for all the studied salts. Their behaviour is non linear and a polynomial fit on the data shown an intercept at zero concentration of 6.2 ± 0.1 cm −1 for the width measured at the half height and of 7.2 ± 0.1 cm −1 for the integrated band width. The band profiles which have been measured by several methods found and asymmetry in the high wavenumber side of the band for Li + and Na + while for the other salts the profile remain symmetrical. The changes in the band parameters and band profiles observed for ν 1 (SO 4 2− ) mode in the present work are interpreted in terms of two main factors (a) the changes in the local field experienced by sulfate surrounded by the water-screened cations and (b) the perturbation arising from the different dynamic behaviour of hydration water molecules of the cations. In particular, these results are found to be consistent with the concepts of positive and negative hydration proposed by Samoilov.

A study on the structural phase transitions of ferroelastic [N(CH3)4]2CuCl4 from microhardness measurements

Abstract Measurements of Vickers microhardness (MHv) as a function of temperature has been carried out on [N(CH 3 ) 4 ] 2 CuCl 4 single crystals. The suitability of this technique for the determination of transition temperatures in the paraelastic-incommensurate→ferroelastic (commensurate) phase transitions sequence is shown.

A Raman spectral study of stream waters and efflorescent salts in Rio Tinto, Spain.

Acidic waters and sulfate-rich precipitates are found in mine tailings such as Rio Tinto (Huelva, SW, Spain). In this work we have characterized the chemical constituents of stream water and have identified some efflorescent salts and precipitates by means of Raman spectroscopy. Variable amounts of sulfate and bisulfate are found in the aqueous samples, suggesting changes in the acidity of the solutions. An estimation of the sulfate/water relative abundance is also given. Solid samples are readily identified as gypsum and as mixtures of hydrated hydroxysulfates belonging to the copiapite group. These results are consistent with previous works reporting the mineralogy and water composition of acid mine drainage-related sites, and proves the importance of Raman spectroscopy as a tool for accurate and noninvasive analyses of acid waters and associated geochemistry.

Gypsum-carbonate speleothems from Cueva de las Espadas (Naica mine, Mexico): mineralogy and palaeohydrogeological implications

4Centro de Astrobiología (CSIC-INTA). Crta. Ajalvir, 28850. Torrejón de Ardoz, Madrid, Spain (martinezfj@inta.es) Gázquez F., Calaforra J., Forti P., Rull F. and Martínez-Frías J. 2012. Gypsum-carbonate speleothems from Cueva de las Espadas (Naica mine, Mexico): mineralogy and palaeohydrogeological implications. International Journal of Speleology, 41(2), 211-220. Tampa, FL (USA). ISSN 0392-6672. http://dx.doi.org/10.5038/1827-806X.41.2.8