Amino acid analyses of Antarctic CM2 meteorites using liquid chromatography‐time of flight‐mass spectrometry

Abstract— Amino acid analyses of the Antarctic CM2 chondrites Allan Hills (ALH) 83100 and Lewis Cliff (LEW) 90500 using liquid chromatography‐time of flight‐mass spectrometry (LC‐ToF‐MS) coupled with UV fluorescence detection revealed that these carbonaceous meteorites contain a suite of indigenous amino acids not present in Antarctic ice. Several amino acids were detected in ALH 83100, including glycine, alanine, β‐alanine, γ‐amino‐n‐butyric acid (γ‐ABA), and α‐aminoisobutyric acid (AIB) with concentrations ranging from 250 to 340 parts per billion (ppb). In contrast to ALH 83100, the CM2 meteorites LEW 90500 and Murchison had a much higher total abundance of these amino acids (440–3200 ppb). In addition, ALH 83100 was found to have lower abundances of the α‐dialkyl amino acids AIB and isovaline than LEW 90500 and Murchison. There are three possible explanations for the depleted amino acid content in ALH 83100: 1) amino acid leaching from ALH 83100 during exposure to Antarctic ice meltwater, 2) a higher degree of aqueous alteration on the ALH 83100 parent body, or 3) ALH 83100 originated on a chemically distinct parent body from the other two CM2 meteorites. The high relative abundance of ?‐amino‐n‐caproic acid (EACA) in the ALH 83100 meteorite as well as the Antarctic ice indicates that Nylon‐6 contamination from the Antarctic sample storage bags may have occurred during collection.     

Micro‐PIXE Geochemical Fingerprinting of Nephrite Neolithic Artifacts from Southwest Bulgaria

Neolithic artifacts made of nephrite, □Ca₂(Fe,Mg)₅Si₈O₂₂(OH)_2, are found at prehistoric settlements in Bulgaria. This study investigates these objects based on particle induced X‐ray emission using a scanning nuclear microprobe (micro‐PIXE technique). Seven nephrite artifacts from the Neolithic sites of Kovachevo, Bulgarchevo and Galabnik in southwest Bulgaria were analyzed to quantify their composition and to establish if a correlation exists between the distribution of major and trace elements, color, impurities, and texture. The nephrite artifacts are tremolite in composition, with a proposed ultrabasic origin. Based on the geochemical data obtained by micro‐PIXE, we divide the artifacts into Group 1 objects from the Kovachevo site and Group 2 objects from the Galabnik and Bulgarchevo sites. The analytical data and microprobe analyses are compared with geochemical data of nephrite from across the globe. The results are in a good agreement with previous electron microprobe and electron paramagnetic resonance (EPR) spectroscopy data. Our study provides a better understanding of the mineralogy and geochemistry of nephrite artifacts and helps to address questions regarding origin and the distribution of such materials in Bulgaria and other Balkan countries.     

Analysis and survival of amino acids in Martian regolith analogs

Abstract— We have investigated the native amino acid composition of two analogs of Martian soil, JSC Mars‐1 and Salten Skov. A Mars simulation chamber has been built and used to expose samples of these analogs to temperature and lighting conditions similar to those found at low latitudes on the Martian surface. The effects of the simulated conditions have been examined using high‐performance liquid chromatography (HPLC). Exposure to energetic ultraviolet (UV) light in vacuum appears to cause a modest increase in the concentration of certain amino acids within the materials, which is interpreted as resulting from the degradation of microorganisms. The influence of low temperatures shows that the accretion of condensed water on the soils leads to the destruction of amino acids, supporting the idea that reactive chemical processes involving H₂O are at work within the Martian soil. We discuss the influence of UV radiation, low temperatures, and gaseous CO₂ on the intrinsic amino acid composition of Martian soil analogs and describe, with the help of a simple model, how these studies fit within the framework of life detection on Mars and the practical tasks of choosing and using Martian regolith analogs in planetary research.     

Amino acid analyses of type 3 chondrites Colony,Ornans, Chainpur,and Bishunpur

Abstract– The CO3s Colony and Ornans and LL3s Chainpur and Bishunpur were analyzed for the first time for amino acids using gas chromatography–mass spectrometry (GC‐MS). Type 3 chondrites have relatively unaltered metamorphic and petrological histories. Chainpur was the most amino acid rich of the four type 3 chondrites with a total amino acid abundance of 3330 parts per billion (ppb). The other type 3 chondrites had total amino acid abundances that ranged from 660 to 1110 ppb. A d /l ratio of <0.7 for all proteic amino acids suggests at least some amino acid terrestrial contamination. However, a small fraction of indigenous extraterrestrial amino acids cannot be excluded because of the presence of the nonprotein amino acid α‐aminoisobutyric acid (α‐AIB), and unusually high relative abundances (to glycine) of β‐alanine and γ‐ABA. The comparisons between the free and total amino acid contents of the samples also indicate a low free/total amino acid ratio (ranging from about 1:4 in CO chondrites to about 1:50 in Chainpur), which indicate that amino acids are present mainly in the bound form and were made detectable after acid hydrolysis.     

Amino acids in Antarctic CM1 meteorites and their relationship to other carbonaceous chondrites

Abstract— CM2 carbonaceous chondrites are the most primitive material present in the solar system, and some of their subtypes, the CM and CI chondrites, contain up to 2 wt% of organic carbon. The CM2 carbonaceous chondrites contain a wide variety of complex amino acids, while the CI1 meteorites Orgueil and Ivuna display a much simpler composition, with only glycine and β‐alanine present in significant abundances. CM1 carbonaceous chondrites show a higher degree of aqueous alteration than CM2 types and therefore provide an important link between the CM2 and CI1 carbonaceous chondrites. Relative amino acid concentrations have been shown to be indicative for parent body processes with respect to the formation of this class of compounds. In order to understand the relationship of the amino acid composition between these three types of meteorites, we have analyzed for the first time three Antarctic CM1 chondrites, Meteorite Hills (MET) 01070, Allan Hills (ALH) 88045, and LaPaz Icefield (LAP) 02277, using gas chromatography‐mass spectrometry (GC‐MS) and high performance liquid chromatography‐fluorescence detection (HPLC‐FD). The concentrations of the eight most abundant amino acids in these meteorites were compared to those of the CM2s Murchison, Murray, Mighei, Lewis Cliff (LEW) 90500, ALH 83100, as well as the CI1s Orgueil and Ivuna. The total amino acid concentration in CM1 carbonaceous chondrites was found to be much lower than the average of the CM2s. Relative amino acid abundances were compared in order to identify synthetic relationships between the amino acid compositions in these meteorite classes. Our data support the hypothesis that amino acids in CM‐ and CI‐type meteorites were synthesized under different physical and chemical conditions and may best be explained with differences in the abundances of precursor compounds in the source regions of their parent bodies in combination with the decomposition of amino acids during extended aqueous alteration.     

The amino acid and hydrocarbon contents of the Paris meteorite: Insights into the most primitive CM chondrite

The Paris meteorite is one of the most primitive carbonaceous chondrites. It is reported to be the least aqueously altered CM chondrite, and to have experienced only weak thermal metamorphism. We have analyzed for the first time the amino acid and hydrocarbon contents of this pristine meteorite by gas chromatography–mass spectrometry (GC–MS). When plotting the relative amino acids abundances of several CM chondrites according to the increasing hydrothermal scale (petrologic subtypes), from the CM2.7/2.8 Paris to the CM2.0 MET 01070, Paris has the lowest relative abundance of β‐alanine/glycine (0.15), which fits with the relative abundances of β‐alanine/glycine increasing with increasing aqueous alteration for CM chondrites. These results confirm the influence of aqueous alteration on the amino acid abundances and distribution. The amino acid analysis shows that the isovaline detected in this meteorite is racemic (d /l  = 0.99 ± 0.08; l ‐enantiomer excess = 0.35 ± 0.5%; corrected d /l  = 1.03; corrected l ‐enantiomer excess = ?1.4 ± 2.6%). The identified hydrocarbons show that Paris has n‐alkanes ranging from C₁₆ to C₂₅ and 3‐ to 5‐ring nonalkylated polycyclic aromatic hydrocarbons (PAHs). The lack of alkylated PAHs in Paris seems to be also related to this low degree of aqueous alteration on its parent body. The extraterrestrial hydrocarbon content, suggested by the absence of any biomarker, may well have a presolar origin. The chemistry of the Paris meteorite may thus be closely related to the early stages of the solar nebula with a contribution from interstellar (molecular cloud) precursors.     

Relation entre fabriques de la sanidine et mise en place des magmas trachytiques (exemple de massif de Hradiště, Bohême du nord)

Résumén

La distribution des fabriques dans un dôme trachytique a été analysée sur la base des orientations préférentielles des cristaux de sanidine. L’orientation préférentielle des plans (010) des cristaux de sanidine a été quantifiée par le calcul du tenseur d’orientation. Le sens de cisaillement a été déterminé à l’aide de relations entre les plans S et C.

Les plans (010) des cristaux de sanidine montrent une fabrique résultant d’un aplatissement dans la partie centrale du dôme et d’un cisaillement simple dans les parties marginales. Les critères de cisaillement montrent le mouvement uni forme de magma trachytique à l’échelle de tout le massif. Nous interprétons la disposition des plans S-C et la répartition des fabriques dans le massif à la superposition de lames successives de magma les unes sur les autres. L’acquisition des fabriques dans le massif est comparée aux expériences en compression uniaxiale le Tullis (1976) et la mise en place des magmas trachytiques est assimilée au mouvement d’un piston dans des conditions de basse pression de confinement et de haute vitesse de déformation pendant le stade d’intrusion précuce. Le gonflement faible a modifié tardivement les fabriques initiales surtout dans la partie de déversement et sommitale.     

Polycyclic aromatic hydrocarbons and amino acids in meteorites and ice samples from LaPaz Icefield,Antarctica

Abstract— –We have analyzed ice samples and meteorites from the LaPaz region of Antarctica to investigate the composition of polycyclic aromatic hydrocarbons (PAHs) and amino acids with the goal to understand whether or not there is a compositional relationship between the two reservoirs. Four LL5 ordinary chondrites (OCs) and one CK carbonaceous chondrite were collected as part of the 2003/2004 ANSMET season. Ice samples collected from directly underneath the meteorites were extracted. In addition, exhaust particles from the snowmobiles used during the expedition were collected to investigate possible contributions from this source. The meteorite samples, the particulate matter and solid‐state extracts of the ice samples and the exhaust filters were subjected to two‐step laser mass spectrometry (L2MS) to investigate the PAH composition. For amino acids analysis, the meteorites were extracted with water and acid hydrolyzed, and the extracts were analyzed with offline OPA/NAC derivatization combined with liquid chromatography with UV fluorescence detection and time of flight mass spectrometry (LC‐FD/ToF‐MS). PAHs in the particulate matter of the ice were found to be qualitatively similar to the meteorite samples, indicating that micron‐sized grains of the meteorite may be embedded in the ice samples. The concentration levels of dissolved PAHs in all the ice samples were found to be below the detection limit of the L2MS. The PAH composition of the snowmobile exhaust is significantly different to the one in particulate matter, making it an unlikely source of contamination for Antarctic meteorites. The amino acids glycine, β‐alanine and γ‐amino‐n‐butyric acid that were detected at concentrations of 3 to 19 parts per billion (ppb) are probably indigenous to the Antarctic meteorites. Some of the LaPaz ice samples were also found to contain amino acids at concentration levels of 1 to 33 parts per trillion (ppt), in particular α‐aminoisobutyric acid (AIB), an abundant non‐protein amino acid of extraterrestrial origin found in some carbonaceous chondrites. We hypothesize that this amino acid could have been extracted from Antarctic micrometeorites and the particulate matter of the meteorites during the concentration procedure of the ice samples.     

Role of mysid seasonal migrations in the organic matter transfer in the Curonian Lagoon,south-eastern Baltic Sea

We investigated population dynamics, growth and feeding of an omnivorous mysid, Paramysis lacustris, performing seasonal horizontal migrations in the Curonian Lagoon. In autumn, increased predation pressure and deteriorated feeding conditions, due to zooplankton and phytoplankton decline in the open water, forces mysids to migrate to the shoreline, where large amounts of decaying submersed vegetation occur at the end of plant growth season. Using stable isotope analysis and mixing models, we evaluated relative importance of decaying submersed macrophytes, lagoon phytoplankton and mesozooplankton in the diet of mysids during this period. In September–November, mysids actively grew and produced three cohorts. Specific growth rates of adults (10.9 ± 1.9 mm) and subadults (6 ± 0.5 mm) were 3 and 9% DW d⁻¹, respectively, resulting in population somatic production of 36 g DW m⁻². Both δ¹⁵N and δ¹³C of mysids varied in concert with those in suspended and bottom particulate organic matter (POM) and mesozooplankton. The mixing models estimated that 45% of mysid diets were composed of bottom POM originated from the decaying macrophyte Potamogeton perfoliatus, 45% by suspended POM largely consisting of phytoplankton, while mesozooplankton contributed less than 10% of the diet. This diet composition differs from that in summer, when mysids rely mostly on zooplankton and phytoplankton. Therefore, mysid horizontal migrations and their ability to efficiently utilize littoral detritus improve the efficiency of macrophyte detritus transfer up the food chain and inshore/offshore habitat coupling in the Curonian Lagoon.     

Evidence for Nearly Complete Decoupling of Very Stable Nocturnal Boundary Layer Overland

Concentrations of ²²²Rn at 0.1 m and 6.5 m height above ground level and ²²²Rn flux density were measured during nights characterized by strong cooling, light winds and clear sky conditions in the Carpathian Basin in Hungary. A very stable boundary layer (vSBL) formed on 14 nights between 15 August and 3 September 2009. On 12 nights, an estimated 72% (s.d. 20%) of ²²²Rn emitted from the surface since sunset was retained within the lowest 6.5 m above the ground until sunrise the following morning. On two nights an intermittent increase in wind speed at 9.4 m height was followed by a rise in temperature at 2.0 m height, indicating a larger atmospheric motion that resulted in ²²²Rn at 0.1 m around sunrise being the same as around the preceding sunset. It does not seem to be rare in a large continental basin for a vSBL to be nearly completely decoupled from the atmosphere above for the entire period from sunset to sunrise.