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111.
Nabil El Moçayd Sophie Ricci Nicole Goutal Mélanie C. Rochoux Sébastien Boyaval Cédric Goeury Didier Lucor Olivier Thual 《Environmental Modeling and Assessment》2018,23(3):309-331
Assessing epistemic uncertainties is considered as a milestone for improving numerical predictions of a dynamical system. In hydrodynamics, uncertainties in input parameters translate into uncertainties in simulated water levels through the shallow water equations. We investigate the ability of generalized polynomial chaos (gPC) surrogate to evaluate the probabilistic features of water level simulated by a 1-D hydraulic model (MASCARET) with the same accuracy as a classical Monte Carlo method but at a reduced computational cost. This study highlights that the water level probability density function and covariance matrix are better estimated with the polynomial surrogate model than with a Monte Carlo approach on the forward model given a limited budget of MASCARET evaluations. The gPC-surrogate performance is first assessed on an idealized channel with uniform geometry and then applied on the more realistic case of the Garonne River (France) for which a global sensitivity analysis using sparse least-angle regression was performed to reduce the size of the stochastic problem. For both cases, Galerkin projection approximation coupled to Gaussian quadrature that involves a limited number of forward model evaluations is compared with least-square regression for computing the coefficients when the surrogate is parameterized with respect to the local friction coefficient and the upstream discharge. The results showed that a gPC-surrogate with total polynomial degree equal to 6 requiring 49 forward model evaluations is sufficient to represent the water level distribution (in the sense of the \(\ell _2\) norm), the probability density function and the water level covariance matrix for further use in the framework of data assimilation. In locations where the flow dynamics is more complex due to bathymetry, a higher polynomial degree is needed to retrieve the water level distribution. The use of a surrogate is thus a promising strategy for uncertainty quantification studies in open-channel flows and should be extended to unsteady flows. It also paves the way toward cost-effective ensemble-based data assimilation for flood forecasting and water resource management. 相似文献
112.
Federica Pognant Matteo Bo Chi Vuong Nguyen Pietro Salizzoni Marina Clerico 《Environmental Modeling and Assessment》2018,23(2):157-164
The use of wood biomass as a fuel for domestic and industrial heating systems allows for a reduction of CO2 emissions at a global scale, but it may also result in worse local air quality conditions, due to their emissions of particulate matter. The aim of this study is to assess the actual trend of atmospheric pollution in a study area, assuming that all heating systems are replaced by small size biomass boilers linked to the buildings through district heating network. Ground level concentrations of particulate matter, emitted by different heating systems, are therefore evaluated through numerical simulations performed by means of an atmospheric dispersion model (Sirane). As a first step, we have compared the environmental impact of a woodchip boilers network with that given by the use of traditional heating systems, i.e. wood stoves and natural gas boilers. As a second step, we have analysed the impact of such a network taking into account different emission scenarios, related to different boilers operating conditions. Results show that the environmental performances of a woodchip boilers network can be optimized by combining it with other renewable sources of energy devoted to the supply of hot water. The adopted analysis methodology can be applied to other real or hypothetic punctual sources on the territory. 相似文献
113.
Benito-Garzón Marta Fady Bruno Davi Hendrik Vizcaíno-Palomar Natalia Fernández-Manjarrés Juan 《Regional Environmental Change》2018,18(5):1427-1437
Regional Environmental Change - The adaptation of social-ecological systems such as managed forests depends largely on decisions taken by forest managers who must choose among a wide range of... 相似文献
114.
Charlotte R. Dromard Mathilde Guéné Yolande Bouchon-Navaro Soazig Lemoine Sébastien Cordonnier Claude Bouchon 《Environmental science and pollution research international》2018,25(15):14294-14301
Chlordecone is an organochlorine pesticide, used in the Lesser Antilles from 1972 to 1993 to fight against a banana weevil. That molecule is very persistent in the natural environment and ends up in the sea with runoff waters. The objective of the present study is to evaluate the level of contamination in several trophic groups of marine animals according to their distance from the source of pollution. Samples of suspended matter, macroalgae, herbivorous fishes, detrivorous crustaceans, zooplanktivorous fishes, first- and second-order of carnivorous fishes, and piscivorous fishes have been collected in two sites, located downstream the contaminated sites (Goyave and Petit-Bourg), in three marine habitats (coastal mangroves, seagrass beds located 1.5 km from the shoreline, and coral reefs at 3 km offshore). Animals collected in mangroves were the most contaminated (mean concentrations 193 μg kg?1 in Goyave and 213 μg kg?1 in Petit-Bourg). Samples from seagrass beds presented intermediate concentrations of chlordecone (85 μg kg?1 in Goyave and 107 μg kg?1 in Petit-Bourg). Finally, samples from coral reefs were the less contaminated (71 μg kg?1 in Goyave and 74 μg kg?1 in Petit-Bourg). Reef samples, collected 3 km offshore, were two to three times less contaminated than those collected in mangroves. 相似文献
115.
El Zrelli Radhouan Rabaoui Lotfi Daghbouj Nabil Abda Heithem Castet Sylvie Josse Claudie van Beek Pieter Souhaut Marc Michel Sylvain Bejaoui Nejla Courjault-Radé Pierre 《Environmental science and pollution research international》2018,25(15):14690-14702
Environmental Science and Pollution Research - Since the establishment of the coastal industrial complex in Gabes city (Gulf of Gabes, SE Tunisia), hundred million tons of untreated phosphogypsum... 相似文献
116.
Saskia Buchholz Jürgen Junk Andreas Krein Günther Heinemann Lucien Hoffmann 《Atmospheric environment (Oxford, England : 1994)》2010,44(39):5183-5190
An impact related daily air quality index (DAQx), calculated for 15 air quality monitoring stations (traffic, background, and industry) in Belgium, France, Germany and Luxembourg, was compared to mesoscale atmospheric patterns between 2001 and 2007. Meteorological conditions were described by the Hess and Brezowsky synoptic weather classification system and gridded data of the EU FP6 ENSEMBLES project of total precipitation and mean surface temperature. DAQx values indicate sufficient to poor air quality in the urban area of Brussels and at urban traffic stations, as well as satisfactory air quality at the background stations. The air quality index refers to more than 90% to the presence of high PM10, O3 and NO2 concentrations. SO2 and CO play only a minor role. The investigation of weather regimes indicates that zonal and mixed cyclonic circulation regimes are associated with better air quality than meridional and anticyclonic weather regimes. In general, weather regimes with high daily precipitation lead to better air quality than dryer air masses because of lower contribution of PM10 to the air quality index. A trend analysis of weather regimes from 1978 to 2007 shows significant (α = 0.05) positive trends for weather classes associated with lower PM10 concentrations. The results of a case study at a German station examining the relationship between PM10 concentrations and local meteorological quantities (wind speed and precipitation) confirm the results of the regional analysis. 相似文献
117.
Eliza Bradley Ira Leifer Dar Roberts 《Atmospheric environment (Oxford, England : 1994)》2010,44(38):4973-4981
Hourly total hydrocarbon (THC) data, spanning 1990–2008 from a California air pollution station located near the Coal Oil Point (COP) seep field, were analyzed and clearly showed geologic CH4 emissions as the dominant local source. Annual COP emissions are conservatively estimated as 0.015 Tg CH4 year?1 and represent a natural and concentrated geologic methane source (24 m3 m?2 day?1 gas flux at some active seeps, Clark et al., 2010). For a sense of the scale and potential importance to the regional Southern California methane budget, COP emits an amount equivalent to 8% of the estimated Los Angeles County anthropogenic emissions. Station THC measurements near COP showed a strong wind dependency with elevated levels closely correlated with a sonar-derived spatial distribution of seep field emissions. THC varied seasonally, with a maximum in January and minimum in July and a peak-to-peak amplitude of 0.24 ppm. The seasonal signal was more readily apparent midday (R2 = 0.69 harmonic fit), compared to nighttime and morning (R2 < 0.45). The bimodal diel THC pattern consisted of seasonally-modulated peaks in the morning and evening.THC temporal and spatial trends were consistent with both transport and source emission variations. Long-term, annual seep field emissions consistently decreased on a field-wide basis until the late 1990s, before increasing consistently, most likely as a function of underlying geologic processes. This study demonstrates the value of municipal air quality monitoring stations for insight into local greenhouse gas sources and highlights the non-negligible and variable contribution from marine geologic seepage. 相似文献
118.
Radium isotopes have been used extensively to trace the movement of groundwater as well as oceanic water masses, but these radionuclides (and their daughters) are also useful chronometers for the determination of the time scales of other Earth and environmental processes. The purpose of this overview is to present the application of Ra and Ra daughters in the dating of carbonates. We show that the choice of dating method (decay of excess radionuclide or ingrowth of daughter) depends strongly on the parent/daughter activity ratios in the water in which the carbonate was precipitated. Thus freshly precipitated carbonates uniformly show excesses of 226Ra relative to its parent 230Th, and 226Ra decay can provide ages of carbonates over Holocene time scales. In contrast, carbonates are precipitated in waters of greatly varying 210Pb/226Ra. Corals, deep-sea hydrothermal vent clams and the shelled cephalopod Nautilus live in waters with significant dissolved 210Pb and all show excesses of 210Pb in their carbonate. Bivalve molluscs from nearshore and coastal waters, and carbonates deposited from groundwater environments (e.g. travertines) in which 210Pb is efficiently scavenged from solution, show deficiencies of 210Pb relative to 226Ra. In contrast, fish otoliths strongly discriminate against 210Pb regardless of the environment in which the fish lives. Deficiencies of 228Th relative to 228Ra are common in all carbonates. Useful time ranges for the 210Pb/226Ra and 228Th/228Ra chronometers are ∼100 y and ∼10 y, respectively. 相似文献
119.
Arturo Rodríguez-Blanco Virginie Antoine Emilien Pelletier Jean-François Ghiglione 《Environmental pollution (Barking, Essex : 1987)》2010,158(3):663-1031
The dynamics of total and active microbial communities were studied in seawater microcosms amended with crude or diesel oil at different temperatures (25, 10 and 4 °C) in the presence/absence of organic fertilization (Inipol EAP 22). Total and hydrocarbon-degrading microbes were enumerated by fluorescence microscopy and Most Probable Number (MPN) method, respectively. Total (16S rDNA-based) vs. active (16S rRNA) bacterial community structure was monitored by Capillary-Electrophoresis Single Strand Conformation Polymorphism (CE-SSCP) fingerprinting. Hydrocarbons were analyzed after 12 weeks of incubation by gas chromatography-mass spectrometry. Total and hydrocarbon-degrading microbial counts were highly influenced by fertilization while no important differences were observed between temperatures. Higher biodegradation levels were observed in fertilized microcosms. Temperature and fertilization induced changes in structure of total bacterial communities. However, fertilization showed a more important effect on active bacterial structure. The calculation of Simpson's diversity index showed similar trends among temperatures whereas fertilization reduced diversity index of both total and active bacterial communities. 相似文献
120.
The importance of potentially interacting factors in organisms responses to a stress are often ignored or underestimated in ecotoxicology. In laboratory experiments we investigated how gender, temperature and age influence the behaviour and the physiology of the freshwater amphipod Gammarus roeseli under salinity stress. Our results revealed a significant higher sensitivity of females in survival, ventilation and ionoregulation whereas no inter-age differences were reported. Water temperature also exerted a significant effect in survival and ventilation of G. roeseli. Some of those factors appeared to interact significantly. This study provides evidence that gender can affect organisms responses to a stressor and consequently has to be considered while assessing a stress impact. We discussed the potential relationships between biological and behavioural responses. 相似文献