Microbial diversity in contaminated soils along the T22 trench of the Chernobyl experimental platform

The diversity of bacterial communities exposed to radioactive contamination in Chernobyl soils was examined by a combination of molecular and culture-based approaches. A set of six radioactive soil samples, exhibiting high levels of ¹³⁷Cs contamination, were collected from the T22 trench. Three samples were also collected in nearby soils with low contamination. Complex bacterial community structures were observed in both highly and weakly contaminated samples, using a molecular approach targeting the 16S rRNA gene. However, the presence of specific populations within samples from highly contaminated soils could not be revealed by statistical analysis of the DGGE profiles. More than 200 culturable isolates, representative of dominant morphotypes, were grouped into 83 Operational Taxonomic Units (OTUs) and affiliated to Firmicutes, Actinobacteria, Alpha-, Beta-, Gamma-Proteobacteria and Bacteroïdetes. No specific pattern linked to contamination was observed for these culturable bacteria. The results show that both highly and weakly contaminated soils host a wide diversity of bacteria, suggesting that long term exposure to radionuclides does not lead to the extinction of bacterial diversity.     

Groundwater resources of Uzbekistan: an environmental and operational overview

As a result of the massive irrigation development during the Soviet Union era and intensive chemization of agriculture, the surface runoff quality has been degraded in this arid and endorheic region. Moreover hydraulically related groundwater has also been affected. Excessive irrigation has lead to land salinization, which now threatens the soil quality of significant areas where crop yields would be at risk in the future. Since the collapse of the Soviet Union, institutional changes have been undertaken for the management of natural resources and water infrastructure. At present, underdeveloped and inadequate systems have been practiced with respect to groundwater use and management. This paper analyzes the present extent of groundwater resources with consideration to their reserves, quality evolution, and to technical, institutional and transboundary management practices in Uzbekistan.     

The 3D structure of N132D in the LMC: a late-stage young supernova remnant

We have used the Wide Field Spectrograph (WiFeS) on the 2.3 m telescope at Siding Spring Observatory to map the [O III] 5007 Å dynamics of the young oxygen-rich supernova remnant N132D in the Large Magellanic Cloud. From the resultant data cube, we have been able to reconstruct the full 3D structure of the system of [O III] filaments. The majority of the ejecta form a ring of ～12 pc in diameter inclined at an angle of ～25 degrees to the line of sight. We conclude that SNR N132D is approaching the end of the reverse shock phase before entering the fully thermalized Sedov phase of evolution. We speculate that the ring of oxygen-rich material comes from ejecta in the equatorial plane of a bipolar explosion, and that the overall shape of the SNR is strongly influenced by the pre-supernova mass loss from the progenitor star. We find tantalizing evidence of a polar jet associated with a very fast oxygen-rich knot, and clear evidence that the central star has interacted with one or more dense clouds in the surrounding ISM.     

Volcaniclastic habitats for early life on Earth and Mars: A case study from ∼3.5 Ga-old rocks from the Pilbara, Australia

Within the context of present and future in situ missions to Mars to investigate its habitability and to search for traces of life, we studied the habitability and traces of past life in ∼3.5 Ga-old volcanic sands deposited in littoral environments an analogue to Noachian environments on Mars. The environmental conditions on Noachian Mars (4.1-3.7 Ga) and the Early Archaean (4.0-3.3 Ga) Earth were, in many respects, similar: presence of liquid water, dense CO₂ atmosphere, availability of carbon and bio-essential elements, and availability of energy. For this reason, information contained in Early Archaean terrestrial rocks concerning habitable conditions (on a microbial scale) and traces of past life are of relevance in defining strategies to be used to identify past habitats and past life on Mars.One such example is the 3.446 Ga-old Kitty’s Gap Chert in the Pilbara Craton, NW. Australia. This formation consists of volcanic sediments deposited in a coastal mudflat environment and is thus a relevant analogue for sediments deposited in shallow water environments on Noachian Mars. Two main types of habitat are represented, a volcanic (lithic) habitat and planar stabilized sediment surfaces in sunlit shallow waters. The sediments hosted small (<1 μm in size) microorganisms that formed colonies on volcanic particle surfaces and in pore waters within the volcanic sediments, as well as biofilms on stabilised sediment surfaces. The microorganisms included coccoids, filaments and rare rod-shaped organisms associated with microbial polymer (EPS). The preserved microbial community was apparently dominated by chemotrophic organisms but some locally transported filaments and filamentous mat fragments indicate that possibly photosynthetic mats formed nearby. Both microorganisms and sediments were silicified during very early diagenesis.There are no macroscopic traces of fossilised life in these volcanic sediments and sophisticated instrumentation and specialized sample preparation techniques are required to establish the biogenicity and syngenicity of the traces of past life. The fact that the traces of life are cryptic, and the necessity of using sophisticated instrumentation, reinforces the challenges and difficulties of in situ robotic missions to identify past life on Mars. We therefore recommend the return of samples from Mars to Earth for a definitive search for traces of life.     

ANIE: A mathematical algorithm for automated indexing of planar deformation features in quartz grains

Abstract– Planar deformation features (PDFs) in quartz, one of the most commonly used diagnostic indicators of shock metamorphism, are planes of amorphous material that follow crystallographic orientations, and can thus be distinguished from non‐shock‐induced fractures in quartz. The process of indexing data for PDFs from universal‐stage measurements has traditionally been performed using a manual graphical method, a time‐consuming process in which errors can easily be introduced. A mathematical method and computer algorithm, which we call the Automated Numerical Index Executor (ANIE) program for indexing PDFs, was produced, and is presented here. The ANIE program is more accurate and faster than the manual graphical determination of Miller–Bravais indices, as it allows control of the exact error used in the calculation and removal of human error from the process.     

Sequential and climatic framework of the growth and demise of a carbonate platform: implications for the peritidal cycles (Late Jurassic,North‐eastern France)

The Middle Oxfordian of the eastern Paris Basin constitutes a remarkable example of the growth and demise of a carbonate platform. Fischer plots, sedimentary and diagenetic features allow the identification of four depositional cycles (S5 to S8) in the Transversarium Zone; they are inserted in a lower frequency cycle of increased/decreased accommodation space (SoIII). The long‐term period of accommodation creation occurred during the older S5 and S6 cycles, the maximum accommodation zone being located in the lower part of the S6 cycle. This high accommodation period was tectonically controlled and was coeval with local distensive activity of a Hercynian fault. A major minimum accommodation zone exists during the S8 cycle. At that time, the platform was isolated and presented both a windward and a leeward margin. The growth of the platform was favoured by a warm and arid climate, oligotrophic conditions and reduced siliciclastic input during a highstand in relative sea‐level. These palaeoenvironmental features favoured the proliferation of phototrophic organisms producing carbonate material. The death of the platform was generated by a reduction in the carbonate production surface during a lowstand in relative sea‐level and by the appearance of mesotrophic conditions induced by the increase in siliciclastic inputs at the beginning of a period with a cooler and more humid climate. In the eastern Paris Basin, during the Middle Oxfordian, the parasequences are ordered and present ‘greenhouse’ characteristics. In contrast, at the beginning of the S8 cycle, the randomness in the thickness of contiguous parasequences increased. Decreased carbonate production during the lowstand caused by a transition from photozoan to heterozoan benthic communities certainly favoured this randomness and the appearance of catch‐down parasequences.     

Audouin's gull chicks as bioindicators of mercury pollution at different breeding locations in the western Mediterranean

Mercury levels of Audouin's gull are amongst the highest for Mediterranean seabirds, and have been mainly attributed to its piscivorous habits in these naturally Hg rich waters. Moreover, two additional factors could enhance its mercury intake: the consumption of discarded fish (which attain higher concentrations) and/or feeding in areas receiving Hg anthropogenic inputs. In order to differentiate the relevance of both sources we analysed Hg and stable isotopes of chick feathers from different breeding locations in western Mediterranean: one in its northern part (Ebro Delta) and two southern (Chafarinas Isl. and Alborán Isl.). The results from stable isotopes indicate that consumption of discards is higher at Alborán Isl., followed by the Ebro Delta and Chafarinas Isl. Thus, the higher mercury levels found in the Ebro Delta cannot be explained uniquely by the contribution of discarded fish to diet, but local pollution caused by the river Ebro waters accounts for Hg differences observed.     

Groundwater resources use and management in the Amu Darya River Basin (Central Asia)

This paper analyses groundwater resources use and management in the socio-economic context of the Amu Darya River Basin which covers a part of the following landlocked Central Asian countries: Afghanistan, Tajikistan, Turkmenistan and Uzbekistan. These agrarian nations for sustaining their vital agricultural productions started to use groundwater during the recent drought years (1998–2001) because of its relatively good quality and quantity and as an alternative to highly mineralized surface waters. Present extent of groundwater resources use is discussed with consideration to their reserves, quality, and institutional management and transboundary aspects within the basin. After the collapse of the centralized water resources management system and infrastructure of the former Soviet Union, new underdeveloped systems are being practiced over the whole Amu Darya River Basin. The critical situation of groundwater management in Afghanistan is also discussed. This work attempts to document the management and use of groundwater in the Amu Darya Basin and present time management realities, with fragmented and weak national and regional regulation on groundwater. Special attention is given to groundwater resources in irrigated agriculture, which increased use in all countries of the basin is due to quick access to underground resources and relatively good quality and quantity.     

Influence of species and rain event characteristics on stemflow volume in a temperate mixed oak–beech stand

This study aimed at analysing the effects of biological and meteorological factors on stemflow generation in a temperate mixed oak (Quercus petraea Liebl.) and beech (Fagus sylvatica L.) stand. A statistical model was developed to predict single‐event individual stemflow volume from trunk circumference and rainfall depth allowing mechanistic stemflow parameters to be deduced from the model, namely stemflow rates (SF_rate), storage of water on tree organs (S_t) and rainfall thresholds for stemflow (RF_min). SF_rate and S_t increased with increasing trunk circumference while RF_min was not significantly influenced by tree size. RF_min and, for a given tree size, S_t were higher for oak than for beech, and inversely for SF_rate. For each species, RF_min was higher for the leaved season than for the leafless period, while the opposite was found for SF_rate, and S_t was not significantly affected by the season. Increasing wind speed during rain increased SF_rate, lowered RF_min and did not influence S_t. In contrast, S_t and RF_min tended, respectively, to decrease and to increase with increasing values of the ratio between the cumulated potential evaporation during the dry period preceding the rain event and the volume of the preceding rainfall (Eva p_ADP/R_previous). Stemflow volume, which results from the combined effects of the previous parameters, was higher for beech than for oak and also higher during the leafless period than during the leaved period; these differences were large for the smallest events but decreased rapidly as rainfall depth increased. In addition, an enhancing and a depressing effect on stemflow volume were shown for the average wind speed during rain and for the ratio Eva p_ADP/R_previous, respectively. Copyright © 2008 John Wiley & Sons, Ltd.     

Resonances in Multiple Planetary Systems

Since the first extrasolar planet was discovered about 10 years ago, a major point of dynamical investigations was the determination of stable regions in extrasolar planetary systems where additional planets may exist. Using numerical methods, we investigate the dynamical stability in known multiple planetary systems (HD74156, HD38529, HD168443, HD169830) with special interest on the region between the two known planets and on the mean motion resonances inside this region. As a dynamical model we take the restricted 4-body problem containing the host star, the two planets and massless test-planets. For our numerical integrations, we used the Lie-integrator and additionally the Fast Lyapunov Indicators as a tool for detecting chaotic motion. We also investigated the inner resonances with the outer planet and the outer resonances with the inner planet with test-planets located inside the resonances.