WSO-UV progress and expectations

The World Space Observatory Ultraviolet (WSO-UV) is the space mission that will grant access to the ultraviolet (UV) range in the post Hubble epoch. WSO-UV is equipped with instrumentation for imaging and spectroscopy and it is fully devoted to UV astronomy. In this article, we outline the WSO-UV mission model and present the current status of the project.     

Pleurozium schreberi as bioindicator of mercury pollution in heavily industrialized region

This research is continuation of the investigation of metal accumulation in native and transplanted moss Pleurozium schreberi in the most industrialized and affected region in Poland (Upper Silesia). We tested the hypotheses that in Upper Silesia transplants of P. schreberi may be used in a 90 days bioindication experiment in case native specimens are absent; a 90 days exposure of transplanted P. schreberi was long enough for evaluation of Hg pollution of the environment. An assay was carried out with native mosses at 27 polluted sites and mosses from an uncontaminated control site transplanted to the same 27 polluted sites. P. schreberi collected from the same sites as classified for more and less polluted basing on Pb and Zn concentrations show quite different pattern of pollution with mercury; The accumulation of Hg by the transplants increased much faster in the first 45 days of the experiment (accumulation factor 1.5–6.7; mean 3.4?±?0.5) in comparison with the second period from day 45 to 90 (accumulation factor 1.0–1.6; mean 1.2?±?0.1). The 90 days exposure of transplanted P. schreberi was long enough for evaluation of Hg pollution of the environment. Transplants of P. schreberi may be used in a 90 days bioindication experiment in case native specimens are absent.     

The retention of ammonia and sulfur dioxide during riming of ice particles and dendritic snow flakes: laboratory experiments in the Mainz vertical wind tunnel

Laboratory experiments were carried out in the Mainz vertical wind tunnel to determine the retention of the trace gases ammonia and sulfur dioxide dissolved in supercooled cloud droplets during riming. The conditions during riming were similar to the ones in atmospheric mixed phase clouds: temperatures from ?18 °C to ?5 °C, liquid water contents between 1 and 1.5 g m^?3, liquid drop radii between 10 and 20 μm, liquid phase concentrations from 1 to 22 mg/l. As collectors, floating ice particles and snow flakes with diameters between 6 mm and 1.5 cm were used. After riming the retention coefficients, i.e. the fractions of the species which remained in the ice phase after freezing were determined. Retention coefficients lying between 0.1 and 1.0 were measured depending on the solubility and dissociation of the trace gas, liquid phase concentration, ambient air temperature, and shape of rimed collector. This can be explained from the chemists’ point of view by the effective Henry’s law constant of the species and physically with the rate of latent heat removal from the rimed collector during freezing. Parameterizations derived from the different experimental cases describe the retention coefficients as a function of temperature. In general, an average retention of ammonia of 92?±?21 % was determined independently of liquid phase concentration while mean values for sulfur dioxide were 53?±?10 % at low liquid phase concentrations and 29?±?7 % at high liquid phase concentrations.     

Impact glass spherules in the Chicxulub K‐Pg event bed at Beloc,Haiti: Alteration patterns

We have investigated six impact glass spherules from the K‐Pg event bed at Beloc, Haiti, using optical and electron microscopy, electron microprobe and in situ laser ablation–mass spectrometry (LA‐ICP‐MS; 37 trace elements, spot size 90–35 μm), in order to understand geochemical changes during alteration. The mm‐sized glass spherules are partly or totally altered to smectite, but original textural features are preserved. The average trace‐element composition of glass matches that one of the upper continental crust. Hints for a “meteoritic component” are lacking (Ni/Cr < 1.3; Pt below detection limit). Compared to this fresh glass, smectites are strongly depleted in trace elements, except for Li, Sc, V, Ni, Ga, Ge, and Ba. The chondrite‐normalized REE distribution patterns are flat with subchondritic abundances, related to their very low degree of crystallinity. We observe a positive Eu and a strong negative Ce anomaly; the latter is explained by formation of an organic Ce⁴⁺‐complex, soluble under reducing conditions. Zr/Hf of glasses and smectites is chondritic to superchondritic (35–40), whereas Nb/Ta in smectite is subchondritic (5–12) compared to Nb/Ta in the glass (~14–18). The low Nb/Ta is due to the low Nb concentrations in the smectite. Using in situ techniques with high spatial resolution, we have documented for the first time the significant changes in diagnostic elemental ratios during alteration of glass spherules. This has to be taken into account in the interpretation of geochemical data of not only impact materials but also volcanic glass, especially if bulk rock methods are used.     

Amino acid analyses of R and CK chondrites

Exogenous delivery of amino acids and other organic molecules to planetary surfaces may have played an important role in the origins of life on Earth and other solar system bodies. Previous studies have revealed the presence of indigenous amino acids in a wide range of carbon‐rich meteorites, with the abundances and structural distributions differing significantly depending on parent body mineralogy and alteration conditions. Here we report on the amino acid abundances of seven type 3–6 CK chondrites and two Rumuruti (R) chondrites. Amino acid measurements were made on hot water extracts from these meteorites by ultrahigh‐performance liquid chromatography with fluorescence detection and time‐of‐flight mass spectrometry. Of the nine meteorites analyzed, four were depleted in amino acids, and one had experienced significant amino acid contamination by terrestrial biology. The remaining four, comprised of two R and two CK chondrites, contained low levels of amino acids that were predominantly the straight chain, amino‐terminal (n‐ω‐amino) acids β‐alanine, and γ‐amino‐n‐butyric acid. This amino acid distribution is similar to what we reported previously for thermally altered ureilites and CV and CO chondrites, and these n‐ω‐amino acids appear to be indigenous to the meteorites and not the result of terrestrial contamination. The amino acids may have been formed by Fischer–Tropsch‐type reactions, although this hypothesis needs further testing.     

A search for shocked quartz grains in the Allerød‐Younger Dryas boundary layer

The Younger Dryas impact hypothesis suggests that multiple airbursts or extraterrestrial impacts occurring at the end of the Allerød interstadial resulted in the Younger Dryas cold period. So far, no reproducible, diagnostic evidence has, however, been reported. Quartz grains containing planar deformation features (known as shocked quartz grains), are considered a reliable indicator for the occurrence of an extraterrestrial impact when found in a geological setting. Although alleged shocked quartz grains have been reported at a possible Allerød‐Younger Dryas boundary layer in Venezuela, the identification of shocked quartz in this layer is ambiguous. To test whether shocked quartz is indeed present in the proposed impact layer, we investigated the quartz fraction of multiple Allerød‐Younger Dryas boundary layers from Europe and North America, where proposed impact markers have been reported. Grains were analyzed using a combination of light and electron microscopy techniques. All samples contained a variable amount of quartz grains with (sub)planar microstructures, often tectonic deformation lamellae. A total of one quartz grain containing planar deformation features was found in our samples. This shocked quartz grain comes from the Usselo palaeosol at Geldrop Aalsterhut, the Netherlands. Scanning electron microscopy cathodoluminescence imaging and transmission electron microscopy imaging, however, show that the planar deformation features in this grain are healed and thus likely to be older than the Allerød‐Younger Dryas boundary. We suggest that this grain was possibly eroded from an older crater or distal ejecta layer and later redeposited in the European sandbelt. The single shocked quartz grain at this moment thus cannot be used to support the Younger Dryas impact hypothesis.