The Role of Oxidation Compounds in Biofilm Growth on Polyethylene Geomembrane Barriers Used in Landfill

In a model study, polyethylene was preoxidized and incubated for a period of 7 months at 40°C in two different municipal solid waste leachates. During the postexperimental analyses, specific attention was paid to the carbonyl species and carboxylic acid depletion during the environmental exposure because it is well known that carboxylic acids are believed to be a potential substrate for the development of microorganisms. The results showed that the carbonyl as well as the carboxylic acid depletion observed follows first-order kinetics. The biofilm formation was characterized using a suite of analytical techniques, and its formation was compared with the carboxylic acid and carbonyl depletion profil

DNA adducts in fish following an oil spill exposure

On 12 December 1999, one third of the load of the Erika tanker, amounting to about 10,000 t crude oil flowed into sea waters close to the French Atlantic Coast. This oil contained polycyclic aromatic compounds (PAC) that are known to be genotoxic. Genotoxic effects induce DNA adducts formation, which can thus be used as pollution biomarkers. Here, we assessed the genotoxic impact of the “Erika” oil spill by DNA adducts detection in the liver of immature fishes (Solea solea) from four locations of the French Brittany coasts. Two months after the spill, a high amount of DNA adducts was found in samples from all locations, amounting to 92–290 DNA adduct per 109 nucleotides. Then total DNA adduct levels decreased to reach about 50 adducts per 109 nucleotides nine months after the spill. In vitro experiments using human cell cultures and fish liver microsomes evidence the genotoxicity of the Erika fuel. They also prove the formation of reactive species able to create DNA adducts. Furthermore, in vitro and in vivo DNA adducts fingerprints are similar, thus confirming that DNA adducts are a result of the oil spill

Background Light in Potential Sites for the ANTARES Undersea Neutrino Telescope

The ANTARES collaboration has performed a series of {\em in situ} measurements to study the background light for a planned undersea neutrino telescope. Such background can be caused by $^{40}$K decays or by biological activity. We report on measurements at two sites in the Mediterranean Sea at depths of 2400~m and 2700~m, respectively. Three photomultiplier tubes were used to measure single counting rates and coincidence rates for pairs of tubes at various distances. The background rate is seen to consist of three components: a constant rate due to $^{40}$K decays, a continuum rate that varies on a time scale of several hours simultaneously over distances up to at least 40~m, and random bursts a few seconds long that are only correlated in time over distances of the order of a meter. A trigger requiring coincidences between nearby photomultiplier tubes should reduce the trigger rate for a neutrino telescope to a manageable level with only a small loss in efficiency.Comment: 18 pages, 8 figures, accepted for publication in Astroparticle Physic

Direct application of compound-specific radiocarbon analysis of leaf waxes to establish lacustrine sediment chronology

Author Posting. © Springer, 2007. This is the author's version of the work. It is posted here by permission of Springer for personal use, not for redistribution. The definitive version was published in Journal of Paleolimnology 39 (2008): 43-60, doi:10.1007/s10933-007-9094-1.This study demonstrates use of compound-specific radiocarbon analysis (CSRA) for dating Holocene lacustrine sediments from carbonate-hosted Ordy Pond, Oahu, Hawaii. Long-chain odd-numbered normal alkanes (n-alkanes), biomarkers characteristic of terrestrial higher plants, were ubiquitous in Ordy Pond sediments. The δ13C of individual n-alkanes ranged from −29.9 to −25.5‰, within the expected range for n-alkanes synthesized by land plants using the C3 or C4 carbon fixation pathway. The 14C ages of n-alkanes determined by CSRA showed remarkably good agreement with 14C dates of rare plant macrofossils obtained from nearby sedimentary horizons. In general, CSRA of n-alkanes successfully refined the age-control of the sediments. The sum of n-alkanes in each sample produced 70–170 μg of carbon (C), however, greater age errors were confirmed for samples containing less than 80 μg of C. The 14C age of n-alkanes from one particular sedimentary horizon was 4,155 years older than the value expected from the refined age-control, resulting in an apparent and arguable age discrepancy. Several lines of evidence suggest that this particular sample was contaminated by introduction of 14C-free C during preparative capillary gas chromatography. This study simultaneously highlighted the promising potential of CSRA for paleo-applications and the risks of contamination associated with micro-scale 14C measurement of individual organic compounds.This project was funded by Petroleum Research Fund (PRF #40088-ACS) and in part by Sigma Xi, The Scientific Research Society (Grants in aid of research, 2003)

Dark Matter Searches with the ANTARES Neutrino Telescope

[EN] The MOSCAB experiment (Materia OSCura A Bolle) uses the Geyser technique for dark matter search. The results of the first 0.5 kg mass prototype detector using superheated C3F8 liquid were very encouraging, achieving a 5 keV nuclear recoil threshold with high insensitivity to gamma radiation. Additionally, the technique seems to be easily scalable to higher masses for both in terms of complexity and costs, resulting in a very competitive technique for direct dark matter search, especially for the spin dependent case. Here, we report as well in the construction and commissioning of the big detector of 40 kg at the Milano-Bicocca University. The detector, the calibration tests and the evaluation of the background will be presented. Once demonstrated the functionality of the detector, it will be operated at the Gran Sasso National Laboratory in 2015.We acknowledge the financial support of the Spanish Ministerio de Ciencia e Innovación (MICINN) and Ministerio de Economía y Competitividad (MINECO), Grants FPA2012-37528-C02-02, and Consolider MultiDark CSD2009-00064, and of the Generalitat Valenciana, Grants ACOMP/2014/153 and PrometeoII/2014/079.Ardid Ramírez, M. (2016). Dark Matter Searches with the ANTARES Neutrino Telescope. Nuclear and Particle Physics Proceedings. 273:378-382. https://doi.org/10.1016/j.nuclphysbps.2015.09.054S37838227

Elaboration of a new compositional kinetic schema for oil cracking

International audienceThe aim of this work is to get new insights into oil cracking mechanisms. The investigation was focused on the thermal stability of the heavy chemical classes such as the C14+ saturates, C14+ aromatics, and the polar fraction (resins + asphaltenes). Artificial maturation was performed in closed pyrolysis system in the temperature range 300375 C for following a large range of conversion for the three initial chemical classes. Pyrolysis products are described as H2S, C1, C2, C3C4 gases, C6C14 saturates, C6C14 aromatics, C14+ saturates, C14+ aromatics, NSOs and prechar. In a first step, the total C14+ aromatics of the initial oil was isolated and artificially matured. They generated a significant part of saturated compounds and new heavy aromatics which were assumed to be methylated structures. The proportion of initial and produced aromatics was determined based on the decrease of the hydrogen content. Then, a kinetic model was elaborated for their specific bulk and compositional kinetic parameters which was taken as an initial guess when optimising the global kinetic model for the total C14+ oil. A tentative global kinetic model for the total C14+ oil was elaborated which well simulated laboratory experiments for both global conversions and yields of generated products. When this model is used for extrapolating laboratory results to natural reservoirs assuming a geothermal heating rate of 2 C/Ma, predicted oil thermal behavior is not in contradiction with observed field data. Indeed, aromaticity is decreasing above 140 C whereas, the yield of C14+ saturates starts to decrease above 170180 C. However this comparison is only qualitative since this model was not integrated into a real case study in which the full process of generationexpulsion and oil cracking must be totally described. The reverse relative thermal stability of the C14+ saturates and aromatics between laboratory and geological conditions is explained by the large difference of A and E of the two chemical classes. Finally, this model was elaborated on a Type II oil only and needs to be tested also on other oils of different chemical composition, either paraffinic or enriched in NSOs

Deciphering uncultured communities of microbes responsible for methanization of cellulose in simulated landfills

International audienceCellulosic materials are important constituent of MSW (paper-cardboard, green waste, some kitchen wastes and textiles…). It is responsible for about 80% of the methane production of landfilled waste (2). Moreover, once methanogenesis is established, hydrolysis of cellulosic material is kinetically limiting the MSW stabilization process in landfills. The overall degradation scheme for cellulose in landfills has been described decades ago. However, more detailed information on the different reactions and microbes involved in the degradation process is still scarce. Microbiologists have indeed to face the problem that most of the microbes inhabiting environmental samples such as those recovered from landfills cannot be isolated and cultivated in the laboratory (1). Culture-independent techniques have therefore to be used to allow accurate description and understanding of these microbial ecosystems. In this framework, rDNA based approaches have become a kind of gold standard for studies on communities of uncultured microbes. However, these methods do not allow to address a key question for the comprehensive understanding of the microbiologically-mediated degradation process: which microbe catalyze which reaction