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301.
Stamatina Th. Rassia Constantinos I. Siettos 《Environmental Modeling and Assessment》2010,15(5):411-418
Emergency evacuation of office buildings, in the event of a life-threatening situation such as a fire incident, is a function
of various factors ranging from architectural to socio-behavioral ones. We show how individual-based modeling approaches such
as molecular dynamics can be coupled with behavioral responses in panic situations, in order to quantify in a systematic way
the impact of human familiarity to the space, during emergency evacuation. The ultimate goal is to identify certain crucial
design features that can help in engineering better evacuation plans. 相似文献
302.
Vincent Martinet Olivier Thébaud Alain Rapaport 《Environmental Modeling and Assessment》2010,15(6):503-517
In this paper, we develop a framework for (a) the study of sustainability of dynamic bioeconomic systems and (b) the definition
of recovery paths from unsustainable situations. We assume that the system follows a sustainable trajectory if it evolves
over time within a set of multidimensional constraints. We use the mathematical concept of viability to characterize sustainability.
Recovery paths are studied with regards to their duration and their acceptability. This general framework is applied to the
issue of recovering sustainable fisheries. We define sustainability in a fishery as the requirement that a set of economic,
ecological, and social constraints is satisfied at all times. Recovery paths are characterized by the time required to obtain
sustainable exploitation conditions in the fishery and by the acceptable recovery costs for fishermen. In particular, we identify
the recovery path which minimizes the time of crisis under a minimum transition profit constraint. We then describe the trade-off
between speed and accepted costs of recovery paths, by comparing “Hare”-like high-speed–high-cost strategies to “Tortoise”-like
low-speed–low-cost strategies. We illustrate our results by means of a numerical analysis of the Bay of Biscay Nephrops fishery. 相似文献
303.
G. Argyropoulos Th. Grigoratos M. Voutsinas C. Samara 《Environmental science and pollution research international》2013,20(10):7214-7230
Ambient concentrations of PM10 and associated elemental and ionic species were measured over the cold and the warm months of 2010 at an urban and two rural sites located in the lignite-fired power generation area of Megalopolis in Peloponnese, southern Greece. The PM10 concentrations at the urban site (44.2?±?33.6 μg m?3) were significantly higher than those at the rural sites (23.7?±?20.4 and 22.7?±?26.9 μg m?3). Source apportionment of PM10 and associated components was accomplished by an advanced computational procedure, the robotic chemical mass balance model (RCMB), using chemical profiles for a variety of local fugitive dust sources (power plant fly ash, flue gas desulfurization wet ash, feeding lignite, infertile material from the opencast mines, paved and unpaved road dusts, soil), which were resuspended and sampled through a PM10 inlet onto filters and then chemically analyzed, as well as of other common sources such as vehicular traffic, residential oil combustion, biomass burning, uncontrolled waste burning, marine aerosol, and secondary aerosol formation. Geological dusts (road/soil dust) were found to be major PM10 contributors in both the cold and warm periods of the year, with average annual contribution of 32.6 % at the urban site vs. 22.0 and 29.0 % at the rural sites. Secondary aerosol also appeared to be a significant source, contributing 22.1 % at the urban site in comparison to 30.6 and 28.7 % at the rural sites. At all sites, the contribution of biomass burning was most significant in winter (28.2 % at the urban site vs. 14.6 and 24.6 % at the rural sites), whereas vehicular exhaust contribution appeared to be important mostly in the summer (21.9 % at the urban site vs. 11.5 and 10.5 % at the rural sites). The highest contribution of fly ash (33.2 %) was found at the rural site located to the north of the power plants during wintertime, when winds are favorable. In the warm period, the highest contribution of fly ash was found at the rural site located to the south of the power plants, although it was less important (7.2 %). Moderate contributions of fly ash were found at the urban site (5.4 and 2.7 % in the cold and the warm period, respectively). Finally, the mine field was identified as a minor PM10 source, occasionally contributing with lignite dust and/or deposited wet ash dust under dry summer conditions, with the summertime contributions ranging between 3.1 and 11.0 % among the three sites. The non-parametric bootstrapped potential source contribution function analysis was further applied to localize the regions of sources apportioned by the RCMB. For the majority of sources, source regions appeared as being located within short distances from the sampling sites (within the Peloponnesse Peninsula). More distant Greek areas of the NNE sector also appeared to be source regions for traffic emissions and secondary calcium sulfate dust. 相似文献
304.
Jan I. Freijer Henk J.Th. Bloemen 《Journal of the Air & Waste Management Association (1995)》2013,63(2):292-300
ABSTRACT Information about the ratio between indoor and outdoor concentrations (IO ratios) of air pollutants is a crucial component in human exposure assessment. The present study examines the relationship between indoor and outdoor concentrations as influenced by the combined effect of time patterns in outdoor concentrations, ventilation rate, and indoor emissions. Two different mathematical approaches are used to evaluate IO ratios. The first approach involves a dynamic mass balance model that calculates distributions of transient IO ratios. The second approach assumes a linear relationship between indoor and outdoor concentrations. We use ozone and benzene as examples in various modeling exercises. The modeled IO ratio distributions are compared with the results obtained from linear fits through plots of indoor versus outdoor concentrations. 相似文献
305.
Marianne E. Hazenkamp-von Arx Thomas Götschi Fellmann Lucy Oglesby Ursula Ackermann-Liebrich Thórarinn Gíslason Joachim Heinrich 《Journal of the Air & Waste Management Association (1995)》2013,63(5):617-628
Abstract The follow-up of a cohort of adults from 29 European centers of the former European Community Respiratory Health Survey (ECRHS) I (1989–1992) will examine the long-term effects of exposure to ambient air pollution on the incidence, course, and prognosis of respiratory diseases, in particular asthma and decline in lung function. The purpose of this article is to describe the methodology and the European-wide quality control program for the collection of particles with 50% cut-off size of 2.5 µm aerodynamic diameter (PM2.5 ) in the ECRHS II and to present the PM2.5 results from the winter period 2000–2001. Because PM2.5 is not routinely monitored in Europe, we measured PM2.5 mass concentrations in 21 participating centers to estimate background exposure in these cities. A standardized protocol was developed using identical equipment in each center (U.S. Environmental Protection Agency Well Impactor Ninety-Six [WINS] and PQ167 from BGI, Inc.). Filters were weighed in a single central laboratory. Sampling was conducted for 7 days per month for a year. Winter mean PM2.5 mass concentrations (November 2000–February 2001) varied substantially, with Iceland reporting the lowest value (5 µg/m3) and northern Italy the highest (69 µg/m3). A standardized procedure appropriate for PM2.5 exposure assessmnt in a multicenter study was developed. We expect ECRHS II to have sufficient variation in exposure to assess long-term effects of air pollution in this cohort. Any bias caused by variation in the characteristics of the chosen monitoring location (e.g., proximity to traffic sources) will be addressed in later analyses. Given the homogenous spatial distribution of PM2.5 , however, concentrations measured near traffic are not expected to differ substantially from those measured at urban background sites. 相似文献
306.
Colloid transport in unsaturated porous media: the role of water content and ionic strength on particle straining 总被引:3,自引:0,他引:3
Torkzaban S Bradford SA van Genuchten MT Walker SL 《Journal of contaminant hydrology》2008,96(1-4):113-127
Packed column and mathematical modeling studies were conducted to explore the influence of water saturation, pore-water ionic strength, and grain size on the transport of latex microspheres (1.1 microm) in porous media. Experiments were carried out under chemically unfavorable conditions for colloid attachment to both solid-water interfaces (SWI) and air-water interfaces (AWI) using negatively charged and hydrophilic colloids and modifying the solution chemistry with a bicarbonate buffer to pH 10. Interaction energy calculations and complementary batch experiments were conducted and demonstrated that partitioning of colloids to the SWI and AWI was insignificant across the range of the ionic strengths considered. The breakthrough curve and final deposition profile were measured in each experiment indicating colloid retention was highly dependent on the suspension ionic strength, water content, and sand grain size. In contrast to conventional filtration theory, most colloids were found deposited close to the column inlet, and hyper-exponential deposition profiles were observed. A mathematical model, accounting for time- and depth-dependent straining, produced a reasonably good fit for both the breakthrough curves and final deposition profiles. Experimental and modeling results suggest that straining--the retention of colloids in low velocity regions of porous media such as grain junctions--was the primary mechanism of colloid retention under both saturated and unsaturated conditions. The extent of stagnant regions of flow within the pore structure is enhanced with decreasing water content, leading to a greater amount of retention. Ionic strength also contributes to straining, because the number of colloids that are held in the secondary energy minimum increases with ionic strength. These weakly associated colloids are prone to be translated to stagnation regions formed at grain-grain junctions, the solid-water-air triple point, and dead-end pores and then becoming trapped. 相似文献
307.
Bentonite clay is considered as possible backfill material for nuclear waste repositories in crystalline rock. The same material may also be a source of clay colloids, which may act as carriers for actinide ions possibly released from the repository. Depending on the geochemical parameters, these colloids may be retained by interaction with mineral surfaces of the host rock. In the present study interaction of carboxylated fluorescent latex colloids, used as a model for bentonite colloids, with natural Grimsel granodiorite and some of its component minerals is studied by fluorescence microscopy and SEM/EDX. The experiments are carried out by varying the pH from 2–10. Strong adsorption is observed at pH values close to or below the points of zero charge (pHpzc) of the mineral surfaces. The influence of Eu(III), used as a chemical homologue for trivalent actinide ions, on colloid adsorption is investigated. Depending on mineral phase and pH, a significant increase of colloid adsorption is observed in the presence of Eu(III). 相似文献
308.
Kunze P Seher H Hauser W Panak PJ Geckeis H Fanghänel T Schäfer T 《Journal of contaminant hydrology》2008,102(3-4):263-272
In the context of deep geological storage of high level nuclear waste the repository will be designed as multiple barrier system including bentonite as buffer/backfill material and the host rock formation as geological barrier. The engineered barrier (bentonite) will be in contact with the host rock formation and consequently it can be expected that bentonite porewater will mix with formation groundwater. We simulate in this study the mixing of Grimsel groundwater (glacial melt water) with synthetic Febex porewater (assuming already saturated state) in a batch-type study and investigate the formation of colloids by laser-induced breakdown detection (LIBD) and SEM-EDX as well as the changes in radionuclide (U, Th, Eu) speciation via ultrafiltration or via time-resolved laser fluorescence spectroscopy (TRLFS) analysis in the case of Cm(III). Based on PHREEQC saturation index (SI) calculations a precipitation of calcite might be expected at low Febex porewater (FPW) content (< 20%), fluorite precipitation at FPW contents < 60% and gibbsite precipitation at FPW contents above 10%. The colloids generated in the mixing zone aggregate when the synthetic FPW content exceeds 10%. LIBD analysis of the time-dependent colloid generation/aggregation revealed a low concentration of colloids to be stable with an estimated plateau value around 100–200 ppt and an average colloid diameter around 30 nm after 140 days reaction time at FPW admixture > 10%. SEM/EDX mostly identifies Al/Si containing colloidal phases and some sulfates could be found under certain admixture ratios. TRLFS studies show that the Cm speciation is strongly influenced by colloid formation in all solutions. In the Febex pore water/GGW mixing zone with high groundwater contents (> 80%) colloids are newly formed and Cm is almost quantitatively associated with most likely polysilicilic acid colloids. 相似文献
309.
310.
Correlating element atmospheric deposition and cancer mortality in Portugal: data handling and preliminary results 总被引:1,自引:0,他引:1
Sarmento S Wolterbeek HT Verburg TG Freitas MC 《Environmental pollution (Barking, Essex : 1987)》2008,151(2):341-351
This study, framed within geographical epidemiology, presents preliminary findings concerning the association between the concentrations of chemical elements obtained through atmospheric biomonitoring with lichens and cancer mortality in the Portuguese population. Exploratory analyses were performed to identify potential confounders for the relationships between chemical elements and neoplasm mortality and to assess the extent of their interference. The results of this study highlight some methodological and conceptual difficulties inherent to observational and geographical studies, in the specific context of the Portuguese population, and the challenge posed by the large numbers of pollutants considered. 相似文献