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1.
PLoS One ; 13(9): e0202528, 2018.
Article de Anglais | MEDLINE | ID: mdl-30208048

RÉSUMÉ

Between 1985 and 2014, the number of US doctoral graduates in Anthropology increased from about 350 to 530 graduates per year. This rise in doctorates entering the work force along with an overall decrease in the numbers of tenure-track academic positions has resulted in highly competitive academic job market. We estimate that approximately79% of US anthropology doctorates do not obtain tenure-track positions at BA/BS, MA/MS, and PhD institutions in the US. Here, we examine where US anthropology faculty obtained their degrees and where they ultimately end up teaching as tenure-track faculty. Using data derived from the 2014-2015 AnthroGuide and anthropology departmental web pages, we identify and rank PhD programs in terms of numbers of graduates who have obtained tenure-track academic jobs; examine long-term and ongoing trends in the programs producing doctorates for the discipline as a whole, as well as for the subfields of archaeology, bioanthropology, and sociocultural anthropology; and discuss gender inequity in academic anthropology within the US.


Sujet(s)
Anthropologie/enseignement et éducation , Emploi/tendances , Corps enseignant/statistiques et données numériques , Femelle , Humains , Mâle , États-Unis
2.
J R Army Med Corps ; 163(4): 259-265, 2017 Aug.
Article de Anglais | MEDLINE | ID: mdl-28320917

RÉSUMÉ

BACKGROUND: Trauma patients requiring massive blood transfusion (MBT) have high morbidity and mortality: early and aggressive use of blood products during immediate resuscitation may improve survival. There is currently a lack of evidence to guide initial identification of these patients which is especially important in areas where plasma may need to be thawed. In the absence of this evidence, this study aimed to robustly evaluate expert opinion by using a Delphi process to identify predictors of massive transfusion. This process can be used to ensure that decision rules include variables that have clinical validity, which may improve translation of rules into clinical practice. METHODS: An international panel of 35 experts was identified through expert advice against specific criteria. Military and civilian experts from the fields of emergency medicine, critical care, anaesthesia, prehospital care, haematology and general/trauma surgery were included. The Delphi Study was carried out over three rounds. Consensus level was predefined at 80%. RESULTS: 195 statements were generated by the panel of which 97 (49.7%) achieved consensus at the 80% level by the end of round 3. Strikingly no clinical observations reached consensus individually. Metabolic acidosis of a base excess of -5.0 or worse, lactate >5 mmol/L and a low haematocrit on arrival were all considered predictive. Some patterns of injury, but few mechanisms of injury, were considered highly predictive of the need of MBT. CONCLUSIONS: This Delphi process has produced a list of parameters that expert clinicians felt were predictive for MBT. This list can be used to inform the generation of decision rules. It is of note that many factors used in current decision rules were not valued by clinical experts-this may be a cause for poor uptake of those rules.


Sujet(s)
Transfusion sanguine , Hémorragie/thérapie , Plaies et blessures/thérapie , Méthode Delphi , Hémorragie/étiologie , Humains , Réanimation , Appréciation des risques , Plaies et blessures/complications
3.
Phys Med Biol ; 59(21): 6549-63, 2014 Nov 07.
Article de Anglais | MEDLINE | ID: mdl-25322212

RÉSUMÉ

Due to their Bragg peak, proton beams are capable of delivering a targeted dose of radiation to a narrow volume, but range uncertainties currently limit their accuracy. One promising beam characterization technique, protoacoustic range verification, measures the acoustic emission generated by the proton beam. We simulated the pressure waves generated by proton radiation passing through water. We observed that the proton-induced acoustic signal consists of two peaks, labeled α and γ, with two originating sources. The α acoustic peak is generated by the pre-Bragg peak heated region whereas the source of the γ acoustic peak is the proton Bragg peak. The arrival time of the α and γ peaks at a transducer reveals the distance from the beam propagation axis and Bragg peak center, respectively. The maximum pressure is not observed directly above the Bragg peak due to interference of the acoustic signals. Range verification based on the arrival times is shown to be more effective than determining the Bragg peak position based on pressure amplitudes. The temporal width of the α and γ peaks are linearly proportional to the beam diameter and Bragg peak width, respectively. The temporal separation between compression and rarefaction peaks is proportional to the spill time width. The pressure wave expected from a spread out Bragg peak dose is characterized. The simulations also show that acoustic monitoring can verify the proton beam dose distribution and range by characterizing the Bragg peak position to within ~1 mm.


Sujet(s)
Acoustique , Simulation numérique , Protonthérapie , Traitement du signal assisté par ordinateur , Transducteurs , Rayons gamma , Méthode de Monte Carlo , Dosimétrie en radiothérapie , Eau/composition chimique
4.
Environ Int ; 59: 363-71, 2013 Sep.
Article de Anglais | MEDLINE | ID: mdl-23892293

RÉSUMÉ

The occurrence of linear- and cyclic-volatile methyl siloxanes (lVMSs and cVMSs, respectively) in various indoor environments, occupational and domestic, in Italy and in the United Kingdom was studied. The results show that the cVMSs are the most abundant, detected in average concentrations that in some cases were as high as 170µgm(-3). Our study highlights the differences that can be observed between various indoor environments (e.g. domestic like bathrooms, bedrooms, or occupational) and between two countries. In most cases, the concentrations found in the UK are higher than in the respective indoor environments in Italy. The assessment of exposure to these two countries for adults and children revealed significant differences both not only in the levels of exposure, but also in the patterns. In Italy, the biggest part of the exposure to VMSs takes place domestically, whereas in the UK, it is observed for occupational environments. Additionally, the compound specific isotopic analysis was employed as a source identification technique. The results are promising mainly for D5 that occurs in higher concentrations, but not for the less abundant lVMSs and cVMSs.


Sujet(s)
Pollution de l'air intérieur/analyse , Siloxanes/analyse , Composés organiques volatils/analyse , Adulte , Enfant , Femelle , Humains , Italie , Mâle , Royaume-Uni
5.
Public Health ; 123(11): 714-22, 2009 Nov.
Article de Anglais | MEDLINE | ID: mdl-19914669

RÉSUMÉ

OBJECTIVES: Crowded hospital emergency departments (EDs) can undermine the ability of a region's safety net to provide safe, timely care. However, data to measure hospital capacity community-wide is generally unavailable. This study aimed to assess hospital crowding, capacity and patient flow in an urban community using the newly developed hospital capacity assessment tool (HCAT). STUDY DESIGN: A survey of the eight acute care hospitals in the District of Columbia (DC) with active EDs. METHODS: Existing emergency care assessment tools were reviewed. Eighteen of the 57 questions on the HCAT were adapted from existing hospital surveys, while the remaining 39 questions were constructed de novo for use in this assessment. Hospitals were provided with paper and electronic versions of the HCAT. RESULTS: All eight DC hospitals completed the HCAT; however, three hospitals were unable to answer many of the questions due to a lack of regular data collection. The HCAT data shows throughput times in DC hospitals that are substantially longer than national averages. CONCLUSIONS: The HCAT is a promising tool for evaluating community-wide emergency care. Findings from the HCAT allowed for the introduction of new ED performance data into the local decision-making process.


Sujet(s)
Surpeuplement , Service hospitalier d'urgences/organisation et administration , Capacité hospitalière , Hôpitaux urbains/statistiques et données numériques , Évaluation des besoins , Taux d'occupation des lits/statistiques et données numériques , District de Columbia , Service hospitalier d'urgences/statistiques et données numériques , Enquêtes sur les soins de santé , Capacité hospitalière/statistiques et données numériques , Hôpitaux privés/statistiques et données numériques , Humains , Durée du séjour/statistiques et données numériques , Transfert de patient , Affectation du personnel et organisation du temps de travail , Projets pilotes , Listes d'attente , Effectif
6.
Environ Pollut ; 157(12): 3336-46, 2009 Dec.
Article de Anglais | MEDLINE | ID: mdl-19604610

RÉSUMÉ

In many densely populated areas, riverine floodplains have been strongly impacted and degraded by river channelization and flood protection dikes. Floodplains act as buffers for flood water and as filters for nutrients and pollutants carried with river water and sediment from upstream source areas. Based on results of the EU-funded "AquaTerra" project (2004-2009), we analyze changes in the dynamics of European river-floodplain systems over different temporal scales and assess their effects on contaminant behaviour and ecosystem functioning. We find that human-induced changes in the hydrologic regime of rivers have direct and severe consequences on nutrient cycling and contaminant retention in adjacent floodplains. We point out the complex interactions of contaminants with nutrient availability and other physico-chemical characteristics (pH, organic matter) in determining ecotoxicity and habitat quality, and draw conclusions for improved floodplain management.


Sujet(s)
Sédiments géologiques/composition chimique , Polluants chimiques de l'eau/composition chimique , Surveillance de l'environnement , Europe , Inondations , Activités humaines , Humains , Rivières/composition chimique
7.
Chemosphere ; 64(2): 256-61, 2006 Jun.
Article de Anglais | MEDLINE | ID: mdl-16527328

RÉSUMÉ

Atmospheric concentrations are reported for the main component of the brominated flame retardant decaBDE (BDE-209) in air samples collected from Southern Ontario for the period January 23-June 06, 2002. Levels ranged from below detection to 105pgm(-3) with virtually all of BDE-209 being trapped by the filter and thus deduced to be sorbed to aerosol particles. Thus, it is likely that the long-range atmospheric transport (LRAT) of BDE-209 is controlled by the transport characteristics of the aerosols. This conclusion that BDE-209 does not have the same potential for LRAT as other more volatile PBDEs is subject to possible complications arising from the uncertainties about the LRAT potential of aerosols.


Sujet(s)
Mouvements de l'air , Polluants atmosphériques/analyse , Air/analyse , Surveillance de l'environnement , Ignifuges/analyse , Éthers phényliques/analyse , Polybromobiphényles/analyse , Air/normes , Éthers de polyhalogénophényle , Ontario , Taille de particule
8.
Environ Sci Technol ; 39(22): 8664-70, 2005 Nov 15.
Article de Anglais | MEDLINE | ID: mdl-16323760

RÉSUMÉ

Haloacetic acids (HAAs) are a family of compounds whose environmental concentrations have been extensively studied, primarily in Europe. Depending on the compound, their sources are believed to be both natural and anthropogenic. To better understand possible sources and contribute to the knowledge of the global distribution of these compounds, especially between the Northern and Southern Hemispheres, samples of precipitation, soils, and conifer needles were collected from Canada, Malawi, Chile, and the U.K. Precipitation samples exhibited highest HAA concentrations in collections from Canada, and lowest in those from Malawi. Malawi samples contained measurable levels of monobromoacetic acid (MBA) (56 ng/ L) unlike those from most other locations (< 9 ng/L). Soil HAA concentration levels were highest in the U.K. (e.g., 7.3 ng/g average TCA) and lowest in Malawi (0.8 ng/g average TCA), with Chile having higher levels (4.8 ng/g average TCA) than Canada (3 ng/g average TCA). Malawi soils contained small amounts of MBA (2 ng/g), in common with the two most southern of the 11 Chilean sites. Analysis of soil cores (10-cm depth sliced at 1 cm) from sites in Malawi and Chile showed that trichloroacetic acid (TCA) generally declined with depth while mono- and dichloroacetic acid (MCA and DCA) showed no trend. MCA, DCA, and TCA concentrations in archived U.K. soil samples increased by factors of 2, 4, and 5-fold over 75 years while TFA showed no consistent trend. Monochloroacetic acid (MCA) was detected in pine needles collected from Malawi. U.K. needle samples had the highest concentrations of all chloroacetic acids (CAAs): MCA, 2-18 ng/g; dichloroacetic acid (DCA), 2-38 ng/g; and trichloroacetic acid (TCA), 28-190 ng/g. Conifer needles from Canada and Chile contained CAAs at levels ranging from < 2 to 16 ng/g wet wt. Trifluoroacetic acid concentrations generally declined with increasing elevation in the samples from the Rocky Mountains in western Canada. The results indicate that concentrations of HAAs are greatest in the industrialized Northern Hemisphere but there are significant amounts of these compounds in the less industrialized Southern Hemisphere.


Sujet(s)
Acétates/analyse , Sol/analyse , Canada , Précipitation chimique , Chili , Acide dichloro-acétique/analyse , Environnement , Industrie , Malawi , Pinus , Feuilles de plante , Polluants du sol , Acide trichloro-acétique/analyse , Royaume-Uni
9.
Environ Sci Technol ; 39(9): 2998-3005, 2005 May 01.
Article de Anglais | MEDLINE | ID: mdl-15926544

RÉSUMÉ

The short-term fate of polychlorinated biphenyl (PCB) and organochlorine (OC) pesticides in the surface snowpack was investigated by taking consecutive air and snow samples over a 12 day period at Tromsø in the Norwegian Arctic. A wide range in PCB and OC pesticide concentrations was observed in snow and was attributed to the systematic decrease in concentrations that occurred over the study period. For example, sigmaPCB concentrations ranged from 2500 to 300 pg L(-1) (meltwater) with a rapid decrease observed during the first 96 h. Rates of decline (ks) conformed to first-order kinetics, with similar rates observed for all compounds measured in this study (k5 = 0.01 +/- 0.001 h(-1)). Because the particle bound fraction accounted for <10% of the individual PCB and OC burden in the snow, then the fraction lost may be accounted for by desorption, following notable increases in snow density (and presumably, decreases in snow surface area). The fraction of chemical present in the fresh snow (phis) was found to be exponentially related to changes in snow density (deltarho). Relatively small increases in p following snowfall result in a large loss of sorbed chemical, presumably due to decreases in snow surface area. Later sampling of the same snow layer, but buried under fresh snowfall, revealed a notable increase in both PCB and OC concentrations. This would indicate a possible downward migration of these chemicals from the fresh snow into deeper snow layers, suggesting that re-emission of desorbed chemical from the interstitial pore spaces to the overlying atmosphere may be complicated by this process.


Sujet(s)
Polluants environnementaux/analyse , Pesticides/analyse , Polychlorobiphényles/analyse , Neige , Régions arctiques , Surveillance de l'environnement , Porosité
10.
Sci Total Environ ; 342(1-3): 145-60, 2005 Apr 15.
Article de Anglais | MEDLINE | ID: mdl-15866272

RÉSUMÉ

PCNs were measured in air and snow during separate field campaigns at Ny-Alesund (April 2001) and Tromsø (February/March 2003) in the Norwegian Arctic. Air concentrations ranged from 27 to 48 and 9 to 47 pg sigmaPCN m(-3) for Ny-Alesund (n=6) and Tromsø (n=10), respectively. These concentrations (including the tri-chlorinated naphthalenes) greatly exceeded concentrations previously measured in the Canadian Arctic, but did fall within the upper range of concentrations observed over the eastern Arctic Ocean and regional seas. Local sources appear to be affecting concentrations observed at both sites, with the presence of several hexa-chlorinated naphthalenes at Tromsø probably attributed to local/regional sources. Use of air mass back trajectories at Tromsø revealed that background air concentrations in the Norwegian Arctic are likely to range between <9 and 20 pg sigmaPCN m(-3) and that contemporary concentrations derived close to potential sources (i.e. arctic towns) may equal or exceed those of PCBs. The mean concentration in surface snow was 350 and 240 pg sigmaPCN L(-1) (meltwater) (or 0.014 and 0.01 pg g(-1) (snow)) at Ny-Alesund and Tromsø, respectively. The wide variation in concentrations observed between fresh snowfalls could be explained by different snow densities (as a surrogate of snow surface area), rather than attributed to varying air concentrations. A statistically significant inverse relationship was found between snow density and concentrations of tri- to penta-chlorinated homologues and compliments similar findings for the polychlorinated biphenyls (PCBs). This suggests that the vapour-sorbed quantity changes rapidly with snow ageing/compaction; with implications for the fate of these chemicals in the Arctic.

11.
Environ Sci Technol ; 39(1): 42-8, 2005 Jan 01.
Article de Anglais | MEDLINE | ID: mdl-15667073

RÉSUMÉ

This paper reports on the first field deployment of rapidly equilibrating thin-film passive air samplers under ambient conditions. The POlymer-coated Glass (POG) samplers have a coating of ethylene vinyl acetate (EVA) less than 1 microm thick applied to a glass surface. This can be dissolved off after exposure and prepared for the quantification of persistent organic pollutants (POPs) that have partitioned into the film during field exposure. In this study, POGs were deployed at various heights on the CN Tower in Toronto, Canada, to investigate the vertical distribution of selected compounds (PCBs, PAHs, organochlorine pesticides) in the atmospheric boundary layer of an urban area. The feasibility of the method to detect POPs from a few cubic meters of air was demonstrated, indicating the potential for rapid, low-volume sampling of air for ambient levels of POPs. PAH levels declined sharply with height, confirming ground-level emissions in urban areas as sources of these compounds; PCBs did the same, although less strongly. Different sampling events detected different vertical distributions of OC pesticides which could be related to local or distantsources, and variations in POPs on the samplers in these different events/heights demonstrate the dynamic nature of sources and atmospheric mixing of POPs.


Sujet(s)
Polluants atmosphériques/analyse , Surveillance de l'environnement/instrumentation , Polluants environnementaux/analyse , Pesticides/analyse , Polychlorobiphényles/analyse , Hydrocarbures aromatiques polycycliques/analyse , Mouvements de l'air , Atmosphère , Villes , Polymères , Sensibilité et spécificité
12.
Environ Sci Technol ; 39(1): 261-7, 2005 Jan 01.
Article de Anglais | MEDLINE | ID: mdl-15667103

RÉSUMÉ

This paper reports on a field calibration and ambient deployment study with rapidly equilibrating thin-film passive air samplers. POlymer-coated Glass (POG) samplers have a coating of ethylene vinyl acetate (EVA) less than 1 microm thick coated on to glass, which can be dissolved off after exposure and prepared for quantification of persistent organic pollutants (POPs) that have partitioned into the film during field exposure. In this study, POGs were exposed for up to 18 d, in a study to assess compound uptake rates and their time to approach equilibrium. Results confirmed theoretical predictions, with time to equilibrium varying between a few hours to ca. 20 d for PCB-18 and PCB-138, respectively. Performance reference compounds and contaminated POGs were used to investigate depuration kinetics, confirming that lighter congeners behave extremely dynamically with substantial losses from the films over periods of a few hours. Repeated deployments of the samplers for different3-d periods yielded detectable levels of a range of PCB congeners, which had partitioned from as little as approximately 2 to 10 m3 air. This highlights the potential utility of POGs for extremely sensitive and dynamic passive air sampling in the future to help improve understanding of sources, environmental fate, and behavior of POPs. Recommendations are made for future improvements/refinements in POG sampling and handling procedures.


Sujet(s)
Polluants atmosphériques/analyse , Surveillance de l'environnement/instrumentation , Surveillance de l'environnement/méthodes , Calibrage , Cinétique , Composés chimiques organiques/analyse , Polymères , Valeurs de référence
13.
Environ Pollut ; 134(1): 153-64, 2005 Mar.
Article de Anglais | MEDLINE | ID: mdl-15572233

RÉSUMÉ

The concept of maximum reservoir capacity (MRC), the ratio of the capacities of the surface soil and of the atmospheric mixed layer (AML) to hold chemical under equilibrium conditions, is applied to selected persistent organic pollutants (POPs) in the surface 'skin' (1 mm) of soils. MRC is calculated as a function of soil organic matter (SOM) content and temperature-dependent K(OA) and mapped globally for selected PCB congeners (PCB-28; -153; -180) and HCB, to identify regions with a higher tendency to retain POPs. It is shown to vary over many orders of magnitude, between compounds, locations and time (seasonally/diurnally). The MRC approach emphasises the very large capacity of soils as a storage compartment for POPs. The theoretical MRC concept is compared to reality and its implications for the global cycling of POPs are discussed. Sharp gradients in soil MRC can exist in mountainous areas and between the land and ocean. Exchanges between oceans and land masses via the atmosphere is likely to be an important driver to the global cycling of these compounds, and net ocean-land transfers could occur in some areas.


Sujet(s)
Pollution de l'air , Composés organiques du phosphore , Polluants du sol , Surveillance de l'environnement/méthodes , Modèles statistiques , Facteurs temps
14.
Chemosphere ; 58(3): 345-54, 2005 Jan.
Article de Anglais | MEDLINE | ID: mdl-15581937

RÉSUMÉ

Blubber samples from grey seal (Halichoerus grypus) pups were collected in 1998 through to 2000. Twenty four newly weaned pups were sampled in November 1998, 13 of which were re-sampled during their first year of life, between March and December 1999, and an additional 48 and 25 samples (new cohorts) were obtained in 1999 (November-December) and 2000 (May-September) respectively. SimgaPBDE concentrations (sum of Di-HxBDEs) ranged from 45 to 1500 ng/g lipid, with a geometric mean of 290 ng/g lipid. BDE 47 dominated the congener profile, followed by BDEs 100, 99, 153 and 154. SimgaPCB concentrations (sum of 41 congeners) ranged from 100 to 93000 ng/g lipid, with a geometric mean of 4600 ng/g lipid, with CB congeners 153, 138 and 180 making up 84% of the total PCB concentrations. The predominant OC pesticides were p,p'-DDE (geometric mean=860 ng/g lipid, range=160-3800 ng/g lipid) and p,p'-DDT (geometric mean=120 ng/g lipid, range=30-670 ng/g lipid). No significant differences were found between males and females, probably due to the young age of the animals. Significant decreases (P<0.01 for PBDEs and P<0.05 for PCBs/OCs) were observed between newly weaned seals in 1998 and 1999, but not for the majority of juveniles in 1999 and 2000. Significant differences (P<0.01) were also found between the different seasons in 1999 newly weaned and juvenile seals, reflecting changes in blubber mass.


Sujet(s)
Polluants environnementaux/analyse , Polybromobiphényles/analyse , Polychlorobiphényles/analyse , Phoques , Tissu adipeux/composition chimique , Animaux , Études de cohortes , Surveillance de l'environnement , Polluants environnementaux/pharmacocinétique , Éthers , Polybromobiphényles/pharmacocinétique , Polychlorobiphényles/pharmacocinétique
15.
Environ Sci Technol ; 38(22): 5993-6001, 2004 Nov 15.
Article de Anglais | MEDLINE | ID: mdl-15573598

RÉSUMÉ

The results from a modeling exercise utilizing the European variant (EVn) BETR multimedia environmental fate model are presented for selected polybrominated diphenyl ethers (PBDEs) of the technical penta- (Pe-) bromodiphenyl ether (BDE) product. The objectives of this study were to test PeBDE emission estimates from the literature for Europe by investigating the consistency between model predictions and ambient measurements to address the ability of the model to predict spatial variability and differences between congeners. Concurrently sampled and analyzed passive sampling air data, together with soil and grass data, were used as key model validation tools. The model steady-state simulations gave generally good agreement with measured data for BDE-47 and -99 with greater discrepancies for heavier congeners (e.g., BDE-153). To predict future atmospheric concentration trends, the model was used in its fully dynamic mode over the period 1970--2010. It was predicted that atmospheric concentrations peaked around 1997, declining with an overall "disappearance" half-life of 4.8 years. Soil and grass levels were underestimated by the model; possible reasons for differences with measurement data are further explored. Finally, the importance of temporally and spatially resolved environmental data sets is highlighted, while improved quantification of degradation half-lives is essential to better understand and predict the behavior of BDE congeners in PeBDE.


Sujet(s)
Polluants atmosphériques/analyse , Hydrocarbures bromés/analyse , Éthers phényliques/analyse , Polybromobiphényles/analyse , Polluants du sol/analyse , Surveillance de l'environnement/méthodes , Éthers , Europe , Éthers de polyhalogénophényle , Modèles théoriques , Éthers phényliques/composition chimique , Polybromobiphényles/composition chimique , Valeur prédictive des tests
16.
Environ Sci Technol ; 38(12): 3224-31, 2004 Jun 15.
Article de Anglais | MEDLINE | ID: mdl-15260317

RÉSUMÉ

A European consumption and atmospheric emissions inventory for pentabrominated diphenyl ethers (PeBDEs) is derived for the period 1970-2000. This time frame has seen a rise in the widespread usage of PeBDE, followed by more recent restrictions/bans. It is estimated that a total of 3000-5000 t of PeBDEs was produced in Europe during this period, with a further 9000-10,000 t imported in finished articles. The main uses for PeBDE are to flame retard consumer products as well as in packaging and solid elastomers. Their major stocks are predicted to be in polyurethane (flexible) foams with up to 30% in cars; more than 10% in furniture foam; and the rest in textiles, building material, packaging, and solid applications. Release of PeBDEs from treated products into environmental media are estimated with a focus on atmospheric inputs via volatilization from their use in cars, upholstered furniture, textiles, television sets, personal computers, and other recycled material. Different emission factors are used to derive different emission scenarios. A peak in atmospheric emissions of between 22 and 31 t of BDE-47 is estimated to have occurred around 1997, with a decline of approximately 20% in 2000. Comparisons with long-term environmental monitoring data revealed that the time trends of human blood and milk concentrations follow similar patterns to the generated emissions, while sediment core levels increase more slowly, probably because they respond to a mix of atmospheric and catchment inputs. The emissions data derived here can be used in a spatially and temporally resolved form as input data for multi-media environmental fate modeling.


Sujet(s)
Polluants atmosphériques/analyse , Polluants atmosphériques/histoire , Ignifuges , Polybromobiphényles/analyse , Polybromobiphényles/histoire , Polluants atmosphériques/sang , Électronique , Surveillance de l'environnement , Europe , Histoire du 20ème siècle , Humains , Industrie , Architecture d'intérieur et mobilier , Produits manufacturés , Polybromobiphényles/sang , Volatilisation
17.
Chemosphere ; 56(3): 227-35, 2004 Jul.
Article de Anglais | MEDLINE | ID: mdl-15172595

RÉSUMÉ

Two novel gas-tight snow samplers (snow-can and snow-tube) are presented and the performance of the snow-can in a field trial was assessed. The methodology for the sampling, extraction and analysis of persistent organic pollutants (POPs) are detailed. These samplers allow the various components of a snow sample to be analysed separately; these included the meltwater (MW), particulate matter (GFF) and vapour in the headspace (HS). Snow samples collected on the Punta Indren glacier in the Italian Alps revealed the occurrence of polychlorinated biphenyls (PCBs), polycyclic aromatic hydrocarbons (PAHs) and organochlorine pesticides (OC). Replicate samples of the same snow type were undertaken as a test of sampling precision. Relative standard deviations (RSDs) for SigmaPCBs and SigmaPAHs were approximately 30% and approximately 35% respectively. The lowest precision was found for the particle-laden snow, notably for the heavier PCB homologues. For the chlorinated compounds, the pesticides lindane and endosulfan-I had the highest levels in snow, with mean concentrations of 402 and 103 pgl(-1) (snow meltwater) respectively. The vapour present in the headspace (HS) comprised a minor component of a collected sample for all compounds, but HS concentrations for three lighter PAHs gave good agreement with those calculated based on their dimensionless Henry's law constants. This suggests that volatilisation during melting of aged snow-can be reasonably predicted with knowledge of the temperature-dependent Henry's law constant.


Sujet(s)
Surveillance de l'environnement/méthodes , Insecticides/analyse , Polychlorobiphényles/analyse , Hydrocarbures aromatiques polycycliques/analyse , Neige , Altitude , Surveillance de l'environnement/instrumentation , Sédiments géologiques/composition chimique , Interactions hydrophobes et hydrophiles , Glace/analyse , Italie , Reproductibilité des résultats , Manipulation d'échantillons/instrumentation , Température , Volatilisation
18.
Environ Sci Technol ; 38(6): 1681-5, 2004 Mar 15.
Article de Anglais | MEDLINE | ID: mdl-15074675

RÉSUMÉ

Air samples were taken for the analysis of persistent organic pollutants before, during, and after the national U.K. "Bonfire Festival" in November 2000. As expected, ambient levels of polynuclear aromatic hydrocarbons (PAHs) increased sharply in response to the widespread diffusive combustion processes that occurred at the time. Polybrominated diphenyl ethers (PBDEs) also increased at the suburban sampling location, to a greater extent than the PAHs. The rise and fall in PBDE concentrations was rapid, coinciding closely with the PAH "combustion markers". These data provide evidence for a novel mechanism responsible for dissipation of PBDEs into the environment. It is hypothesized that products treated with the penta-BDE product--notably household furnishing foams and textiles--have been subject to (unsanctioned) burning on private bonfires; even if the majority of the PBDE burden of such products is debrominated/broken down in the fires, it is shown that only small amounts of the total "stock" of penta product need be emitted to generate the concentrations detected. The mixture of PBDEs in the air during the Bonfire Festival was enriched in higher brominated congeners (e.g., BDE-99, -153, and -154) compared to that in background air. Estimates are made of the masses of compound classes that may have been emitted to the atmosphere during the festival.


Sujet(s)
Polluants atmosphériques/analyse , Incendies , Polybromobiphényles/analyse , Surveillance de l'environnement , Éthers/analyse , Royaume-Uni
20.
Environ Pollut ; 128(1-2): 139-48, 2004.
Article de Anglais | MEDLINE | ID: mdl-14667724

RÉSUMÉ

Although there is indisputable evidence that long-range atmospheric transport (LRAT) of organic contaminants occurs on a global scale, uncertainties remain about the detailed mechanism and extent of this phenomenon as well as the physical-chemical properties which facilitate LRAT. In this study, we discuss how mass balance models and monitoring data can contribute to a fuller understanding of the mechanism and extent of LRAT. Specifically we address the issues of "grasshopping" or "hopping" (the extent to which molecules are subject to multiple hops as distinct from a single emission-deposition event) and "global fractionation" (the differing behavior of chemicals as they are transported). It is shown that simple mass balance models can be used to assist the interpretation of monitoring data while also providing an instrument that can be used to assess the LRAT potential and the extent of hopping that organic substances may experience. The available evidence supports the notion that many persistent organic pollutants experience varying degrees of "hopping" during their environmental journey and as a consequence become fractionated with distance from source.


Sujet(s)
Mouvements de l'air , Polluants atmosphériques/composition chimique , Pollution de l'air , Surveillance de l'environnement/statistiques et données numériques , Composés chimiques organiques/composition chimique , Fractionnement chimique , Hexachloro-benzène/composition chimique , Modèles théoriques , Méthode de Monte Carlo , Polychlorobiphényles/composition chimique
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