Refinar búsqueda
Resultados 141-150 de 315
Using SFA indicators to support environmental policy
1999
van der Voet, Ester | van Oers, Lauran | Guinée, J. B. | de Haes, Helias A Udo
In order to improve the link from Substance Flow Analysis (SFA) studies to environmental policy, a translation is made from the SFA overview of flows and stocks into a limited set of indicators. This set is designed to evaluate a region’s substance regime with regard to environmental quality and sustainable development, including problem shifting in time and space.
Mostrar más [+] Menos [-]Measurements of selected PCBs in open urban ambient air of Madrid (Spain) : First results
1999
García-Alonso, Susana | Pérez-Pastor, Rosa María | Sevillano-Castaño, María Luisa
The focus of this study was to characterize the concentration levels of selected PCBs and compare them to compiled data in order to contribute to the international database. The sampling site is located in the outskirts of Madrid and can be considered an open urban area. 32 samples of air were taken from February 1998 to June 1998 by using a high volume air sampler. Glass fiber filters and polyurethane foam (PUF) were used to collect the paniculate and gas phase material, respectively.PUF plugs were Soxhlet extracted and filters were ultrasonically extracted by using pesticide-grade hexane and dichloromethane, respectively. The cleanup procedure was carried out on a florisil column with hexane and hexane/dichloromethane as elution solvents.GC/MS in a selected ion monitoring mode was used for quantification and 29 selected PCBs congeners were analyzed.
Mostrar más [+] Menos [-]Interactive valuation : the social construction of the value of ecological services
1999
Jiggins, J. | Röling, N.
Absorption cross-sections of atmospheric constituents: NO2, O2, and H2O
1999
Hermans, Christian | Vandaele, Ann C. | Carleer, Michel | Fally, Sophie | Colin, Réginald | Jenouvrier, Alain | Coquart, Bernard | Mérienne, Marie-France
Absorption spectroscopy, which is widely used for concentration measurements of tropospheric and stratospheric compounds, requires precise values of the absorption cross-sections of the measured species. NO₂, O₂ and its collision-induced absorption spectrum, and H₂O absorption cross-sections have been measured at temperature and pressure conditions prevailing in the Earth’s atmosphere. Corrections to the generally accepted analysis procedures used to resolve the convolution problem are also proposed.
Mostrar más [+] Menos [-]Soils and groundwater pollution and remediation
1999
Huang, P. M. | Iskandar, I. K. (Iskandar Karam)
"Soils and Groundwater Pollution and Remediation explores the toxic levels of metals radionuclides inorganics, and anthropogenic organic compounds found in the soils and groundwater of Asia, Africa, and Oceania. This 14-chapter book reviews the distribution, transformation and dynamics of the pollutants. The authors also reflect on the impact of acid rain."--Jacket.
Mostrar más [+] Menos [-]Distribution of volatile organic compounds in Madrid (Spain)
1999
Pérez-Pastor, Rosa María | García-Alonso, Susana | Cabezas, Alberto José Quejido
From November 1995 to October 1996, airborne concentrations of VOCs were measured in the Madrid area to study the organic pollution in general, and the correlation between different pollutants in relation to such parameters as location and season. Mean concentrations for up to 90 compounds were measured at four test sites, including both urban and suburban areas.At the urban sites, maximum concentrations occurred in the autumn and winter, whereas minimum concentrations were reached in summer and spring. Similar changes were obtained for the lesscontaminated site located in the SE of the city, whereas a different pattern was found at the site in the NW of the city due to meteorological aspects. Mean levels of hydrocarbons in Madrid were quite similar to those found in other European cities.Chemometrical techniques were applied to the set of data in order to assess the influence of such factors as traffic, temperature and seasonal variations on the VOC levels.
Mostrar más [+] Menos [-]A review of biomarker compounds as source indicators and tracers for air pollution
1999
Simoneit, Bernd R. T.
An overview of the application of organic geochemistry to the analysis of organic matter on aerosol particles is presented here. This organic matter is analyzed as solvent extractable bitumen/ lipids by gas chromatography-mass spectrometry. The organic geochemical approach assesses the origin, the environmental history and the nature of secondary products of organic matter by using the data derived from specific molecular analyses. Evaluations of production and fluxes, with cross-correlations can thus be made by the application of the same separation and analytical procedures to samples from point source emissions and the ambient atmosphere. This will be illustrated here with typical examples from the ambient atmosphere (aerosol particles) and from emissions of biomass burning (smoke).Organic matter in aerosols is derived from two major sources and is admixed depending on the geographic relief of the air shed. These sources are biogenic detritus (e.g., plant wax, microbes, etc.) and anthropogenic particle emissions (e.g., oils, soot, synthetics, etc.). Both biogenic detritus and some of the anthropogenic particle emissions contain organic materials which have unique and distinguishable compound distribution patterns (C₁₄-C₄₀). Microbial and vascular plant lipids are the dominant biogenic residues and petroleum hydrocarbons, with lesser amounts of the pyrogenic polynuclear aromatic hydrocarbons (PAH) and synthetics (e.g., chlorinated compounds), are the major anthropogenic residues.Biomass combustion is another important primary source of particles injected into the global atmosphere. It contributes many trace substances which are reactants in atmospheric chemistry and soot paniculate matter with adsorbed biomarker compounds, most of which are unknown chemical structures. The injection of natural product organic compounds into smoke occurs primarily by direct volatilization/steam stripping and by thermal alteration based on combustion temperature. Although the molecular composition of organic matter in smoke particles is highly variable, the molecular tracers are generally still source specific. Retene has been utilized as a tracer for conifer smoke in urban aerosols, but is not always detectable. Dehydroabietic acid is generally more concentrated in the atmosphere from the same emission sources. Degradation products from biopolymers (e.g., levoglucosan from cellulose) are also excellent tracers. An overview of the biomarker compositions of biomass smoke types is presented here. Defining additional tracers of thermally-altered and directly-emitted natural products in smoke aids the assessment of the organic matter type and input from biomass combustion to aerosols. The precursor to product approach of compound characterization by organic geochemistry can be applied successfully to provide tracers for studying the chemistry and dispersion of ambient aerosols and smoke plumes.
Mostrar más [+] Menos [-][Reactive walls with iron filings: perspectives and status of Danish activities]
1999
Kjeldsen, P.
[Detailed mapping: is our knowledge sufficient?]
1999
Baumann, J. | Foged, N. | Joergensen, P.
Funnel-and-gate systems for in-situ treatment of contaminated groundwater at former manufactured gas plant sites
1999
Grathwohl, P. | Schad, H.