Caractérisation des sédiments des retenues pour la prévision des risques écotoxicologiques liés aux vidanges

L'acumulation de sédiments dans les retenues de barrages hydro-électriques nécessite de procéder à des opérations régulières de désenvasement indispensables à leur bon fonctionnement.Ces opérations de vidange ont le plus souvent un effet destructeur sur la faune et la flore aquatique.Cet effet destructeur est principalement lié à une diminution de la concentration en oxygène dissous et une augmentation de la teneur en matières en suspension.La méthodologie présentée a pour but d'estimer préalablement à toute vidange les risques écotoxicologlques correspondant à une telle opération. Elle implique d'une part la description et l'analyse physico-chimique des sédiments en place, d'autre part la mesure en laboratoire de la consommation en oxygène dissous des matériaux remis en suspension au cours du temps.La fiabilité d'une telle procédure a été montrée en particulier à l'occasion de vidanges de retenues situées sur le cours de l'Isère.Le protocole est décrit précisément de façon à pouvoir guider les exploitants de retenues à l'occasion des opérations de vidange qu'ils dirigent.Sediment silting up in hydroelectric dams Implies regular draining operations in order to prevent disfunction of the dams.These operations often lead to drastic lethal affects on aquatic fauna and flora.A toxicological study has clearly shown two main factors responsible for acute toxicological effects : dissolved oxygen deficit and suspended solids increase.These effects have been quantified by experimental tests on Brown trout fry (Salmo trutta fario) the results of which are summarized.The second step consisted in the prediction of water quality evolution downstream during dam draining operation, regarding both factors suspected, in order to assess ecotoxicological hazard.The proposed methodology based on a sedimentological study made in Grangent dam, located on river Loire and immediately downstream of St. Etienne urban area, and in St. Hilaire dam situated on the river Isère downstream partIt consists in sampling cored sediments and in measuring dissolved oxygen kinetic by mixing sediments with water In a reactor.The sample conservation as carried out in jar glasses kept at 4 °C.Results are reproducible as long as residual dissolved oxygen concentration is higher than 3 mg/l. If this condition is respected, oxygen consumption is strictly dependent on suspended sediment concentration.An increase in test water temperature makes the oxygen consumption rise.In accordance with these results, recommendations for dissolved oxygen measures are about 5 g/l suspended sediment concentration, with an experimental temperature reaching the temperature observed during dam draining.The variability of the results for different samples depends on the dam studied. Surface tore samples collected in St. Hilaire dam consume dissolved oxygen faster than the same bottom tore samples.However, in Grangent dam, only one surface core sample collected near the dam construction has clearly shown reducing properties. The difference between two dam sediments is very important : Grangent dam sediment have, on average, dissolved oxygen consumption three more times higher than St. Hilaire in the same duration.Taking into account dissolved oxygen kinetics by mixed sediments, and a simple aeration model using water and sediment deposits from downstream dam, may expert both suspended sediment and oxygen consumption evolution.Hazardous mortality of trout fario fry in downstream dam are quickly graphically visualized.Dam draining operator may so assess, for different suspended sediment land the harmful exposition to fish at any distance from it.This knowledge allows him to plan more strictly floodgate working : pointly dissolved oxygen continuous measurement on downstream dam is sufficient to give a mark related to model hazard assessment.The model reliability has been demonstrated by the examination of data collected during St. Hilaire dam draining operation

Investigating Project Success Factors in Post-Disaster Rebuilding Efforts in NYC

On October 29, 2012, Superstorm Sandy caused nearly $19 billion in damages in New York City including damage to 69,000 residential units. A precipitated amount of roughly$4.2 billion in Community Development Block Grant was allocated towards PDR construction. These funds addressed a range of needs, including rebuilding and rehabilitating housing, assisting displaced tenants, and providing aid to businesses. Post-Disaster Rebuilding (PDR) is similar to construction in the modification of an existing facility that involves either renovation, additions, or subtractions to scopes of work to assist the overall performance of the facility. However, PDR goes further in a highly coordinated process involving planning for future disaster events, integrating a temporary facility plan for those displaced, and tackling housing issues for all those affected by natural disasters. PSF (project success factors) consist of activities or elements that are required to ensure the successful completion of the project. Researchers have discussed literature PSF for PDR projects on topics including the importance of shared data modeling for interdisciplinary exchange of information for effective communication and risk reduction, formulating a holistic PDR approach that can be effective and adaptable to future reconstruction efforts (and inclusive of all stakeholders), and assessing the experience levels of all team members. However, existing research into the assessment of the goals for PDR projects is limited, warranting an investigation of construction success factors as it applies to PDR efforts to improve equitable community resettlement and sustainable and resilient structure. A review of the literature was generated to identify accepted project success factors in construction projects, such as the case study of PDR response to Hurricane Sandy in New York City, in helping to identify common themes for success factors. Specifically, three areas will be examined from the case study: 1) Strategy/planning, 2) Resiliency and 3) Communication. Implementing these strategies in PDR projects will assist in the further understanding and success of reconstruction projects in this field of work

The Chlamydomonas genome project: A decade on

The green alga Chlamydomonas reinhardtii is a popular unicellular organism for studying photosynthesis, cilia biogenesis, and micronutrient homeostasis. Ten years since its genome project was initiated an iterative process of improvements to the genome and gene predictions has propelled this organism to the forefront of the omics era. Housed at Phytozome, the plant genomics portal of the Joint Genome Institute (JGI), the most up-to-date genomic data include a genome arranged on chromosomes and high-quality gene models with alternative splice forms supported by an abundance of whole transcriptome sequencing (RNA-Seq) data. We present here the past, present, and future of Chlamydomonas genomics. Specifically, we detail progress on genome assembly and gene model refinement, discuss resources for gene annotations, functional predictions, and locus ID mapping between versions and, importantly, outline a standardized framework for naming genes

Geostationary Emission Explorer for Europe (G3E): mission concept and initial performance assessment

The Geostationary Emission Explorer for Europe (G3E) is a concept for a geostationary satellite sounder that targets at constraining the sources and sinks of the greenhouse gases carbon dioxide (CO2) and methane (CH4) for continental-scale regions. Thereby, its primary focus is on Central Europe. G3E carries a spectrometer system that collects sunlight backscattered from the Earth\u27s surface and atmosphere in the near-infrared (NIR) and shortwave-infrared (SWIR) spectral range. Solar absorption spectra allow for spatiotemporally dense observations of the column-average concentrations of carbon dioxide (XCO2), methane (XCH4), and carbon monoxide (XCO) including sampling of the diurnal variation with several measurements per day during summer. Here, we present the mission concept and carry out an initial performance assessment of the retrieval capabilities. The radiometric performance of the 4 grating spectrometers is tuned to reconcile small ground-pixel sizes (~ 2 km × 3 km at 50° latitude) with short single-shot exposures (∼ 2.9 s) that allow for sampling continental regions such as Central Europe within 2 h while providing sufficient signal-to-noise. The noise errors to be expected for XCO2, XCH4, and XCO are assessed through retrieval simulations for a European trial ensemble. Generally, single-shot precision for the targeted XCO2 and XCH4 is better than 0.5 % with some exception for scenes with low infrared surface albedo observed under low sun conditions in winter. For XCO, precision is generally better than 10 %. Performance for aerosol and cirrus loaded atmospheres is assessed by mimicking G3E\u27s slant view on Europe for an ensemble of atmospheric scattering properties used previously for evaluating nadir-viewing low-Earth-orbit (LEO) satellites. While retrieval concepts developed for LEO configurations generally succeed in mitigating aerosol and cirrus induced retrieval errors for G3E\u27s setup, residual errors are somewhat greater in geostationary orbit (GEO) than in LEO. G3E\u27s deployment in the vicinity of the Meteosat Third Generation (MTG) satellites suggests making synergistic use of MTG\u27s sounding capabilities e.g. with respect to characterization of aerosol and cloud properties or with respect to enhancing carbon monoxide retrievals by combining G3E\u27s solar and MTG\u27s thermal infrared spectra

Geostationary Emission Explorer for Europe (G3E): mission concept and initial performance assessment

The Geostationary Emission Explorer for Europe (G3E) is a concept for a geostationary satellite sounder that aims to constrain the sources and sinks of greenhouse gases carbon dioxide (CO2) and methane (CH4) for continental-scale regions. Its primary focus is on central Europe. G3E carries a spectrometer system that collects sunlight backscattered from the Earth\u27s surface and atmosphere in the near-infrared (NIR) and shortwave-infrared (SWIR) spectral range. Solar absorption spectra allow for spatiotemporally dense observations of the column-average concentrations of carbon dioxide (XCO2), methane (XCH4), and carbon monoxide (XCO). The mission concept in particular facilitates sampling of the diurnal variation with several measurements per day during summer. Here, we present the mission concept and carry out an initial performance assessment of the retrieval capabilities. The radiometric performance of the 4 grating spectrometers is tuned to reconcile small ground-pixel sizes (~2 km × 3 km at 50° latitude) with short single-shot exposures (~2.9 s) that allow for sampling continental regions such as central Europe within 2 h while providing a sufficient signal-to-noise ratio. The noise errors to be expected for XCO2, XCH4, and XCO are assessed through retrieval simulations for a European trial ensemble. Generally, single-shot precision for the targeted XCO2 and XCH4 is better than 0.5 % with some exception for scenes with low infrared surface albedo observed under low sun conditions in winter. For XCO, precision is generally better than 10 %. Performance for aerosol and cirrus loaded atmospheres is assessed by mimicking G3E\u27s slant view on Europe for an ensemble of atmospheric scattering properties used previously for evaluating nadir-viewing low-Earth-orbit (LEO) satellites. While retrieval concepts developed for LEO configurations generally succeed in mitigating aerosol- and cirrus-induced retrieval errors for G3E\u27s setup, residual errors are somewhat greater in geostationary orbit (GEO) than in LEO. G3E\u27s deployment in the vicinity of the Meteosat Third Generation (MTG) satellites has the potential to make synergistic use of MTG\u27s sounding capabilities e.g. with respect to characterization of aerosol and cloud properties or with respect to enhancing carbon monoxide retrievals by combining G3E\u27s solar and MTG\u27s thermal infrared spectra

HCl and ClO in activated Arctic air; first retrieved vertical profiles from TELIS submillimetre limb spectra

The first profile retrieval results of the Terahertz and submillimeter Limb Sounder (TELIS) balloon instrument are presented. The spectra are recorded during a 13-h balloon flight on 24 January 2010 from Kiruna, Sweden. The TELIS instrument was mounted on the MIPAS-B2 gondola and shared this platform with the Michelson Interferometer for Passive Atmospheric Sounding (MIPAS) and the mini- Differential Optical Absorption Spectroscopy (mini-DOAS) instruments. The flight took place within the Arctic vortex at an altitude of ≈34 km in chlorine activated air, and both active (ClO) and inactive chlorine (HCl) were measured over an altitude range of respectively ≈16–32 km and ≈10– 32 km. In this altitude range, the increase of ClO concentration levels during sunrise has been recorded with a temporal resolution of one minute. During the daytime equilibrium, a maximum ClO level of 2.1±0.3 ppbv has been observed at an altitude of 23.5 km. This equilibrium profile is validated against the ClO profile by the satellite instrument Microwave Limb Sounder (MLS) aboard EOS Aura. HCl profiles have been determined from two different isotopes – H35Cl and H37Cl – and are also validated againstMLS. The precision of all profiles is well below 0.01 ppbv and the overall accuracy is therefore governed by systematic effects. The total uncertainty of these effects is estimated to be maximal 0.3 ppbv for ClO around its peak value at 23.5 km during the daytime equilibrium, and for HCl it ranges from 0.05 to 0.4 ppbv, depending on altitude. In both cases the main uncertainty stems from a largely unknown non-linear response in the detector

P2Y2 receptor activation inhibits the expression of the sodium-chloride cotransporter NCC in distal convoluted tubule cells

Luminal nucleotide stimulation is known to reduce Na+ transport in the distal nephron. Previous studies suggest that this mechanism may involve the thiazide-sensitive Na+-Cl− cotransporter (NCC), which plays an essential role in NaCl reabsorption in the cells lining the distal convoluted tubule (DCT). Here we show that stimulation of mouse DCT (mDCT) cells with ATP or UTP promoted Ca2+ transients and decreased the expression of NCC at both mRNA and protein levels. Specific siRNA-mediated silencing of P2Y2 receptors almost completely abolished ATP/UTP-induced Ca2+ transients and significantly reduced ATP/UTP-induced decrease of NCC expression. To test whether local variations in the intracellular Ca2+ concentration ([Ca2+]i) may control NCC transcription, we overexpressed the Ca2+-binding protein parvalbumin selectively in the cytosol or in the nucleus of mDCT cells. The decrease in NCC mRNA upon nucleotide stimulation was abolished in cells overexpressing cytosolic PV but not in cells overexpressing either a nuclear-targeted PV or a mutated PV unable to bind Ca2+. Using a firefly luciferase reporter gene strategy, we observed that the activity of NCC promoter region from −1 to −2,200bp was not regulated by changes in [Ca2+]i. In contrast, high cytosolic calcium level induced instability of NCC mRNA. We conclude that in mDCT cells: (1) P2Y2 receptor is essential for the intracellular Ca2+ signaling induced by ATP/UTP stimulation; (2) P2Y2-mediated increase of cytoplasmic Ca2+ concentration down-regulates the expression of NCC; (3) the decrease of NCC expression occurs, at least in part, via destabilization of its mRNA