Your browser doesn't support javascript.
Mostrar: 20 | 50 | 100
Resultados 1 - 19 de 19
Filtrar
Mais filtros










Base de dados
Intervalo de ano de publicação
1.
Environ Sci Technol ; 51(24): 14273-14282, 2017 Dec 19.
Artigo em Inglês | MEDLINE | ID: mdl-29171748

RESUMO

Chemical transport models are useful tools for evaluating source contributions and health impacts of PM2.5 in the atmosphere. We recently found that concentrations of PM2.5 compounds over Japan were much better reproduced by a volatility basis set model with an enhanced dry deposition velocity of HNO3 and NH3 compared with a two-product yield model. In this study, we evaluated the sensitivities to organic aerosol models of the simulated source contributions to PM2.5 concentrations and of PM2.5-related mortality. Overall, the simulated source contributions to PM2.5 were similar between the two models. However, because of the improvements associated with the volatility basis set model, the contributions of ammonia sources decreased, particularly in winter and spring, and contributions of biogenic and stationary evaporative sources increased in spring and summer. The improved model estimated that emission sources in Japan contributed 35%-48% of the PM2.5-related mortality in Japan. These values were higher than the domestic contributions to average PM2.5 concentrations in Japan (26%-33%) because the domestic contributions were higher in higher population areas. These results indicate that control of both domestic and foreign emissions is necessary to reduce health impacts due to PM2.5 in Japan.


Assuntos
Aerossóis , Poluentes Atmosféricos , Material Particulado , Monitoramento Ambiental , Japão
2.
Environ Sci Technol ; 51(14): 7972-7981, 2017 Jul 18.
Artigo em Inglês | MEDLINE | ID: mdl-28686425

RESUMO

The source-receptor relationship analysis of PAH deposition in Northeast Asia was investigated using an Eulerian regional-scale aerosol chemical transport model. Dry deposition (DD) of PAH was controlled by wind flow patterns, whereas wet deposition (WD) depended on precipitation in addition to wind flow patterns. The contribution of WD was approximately 50-90% of the total deposition, except during winter in Northern China (NCHN) and Eastern Russia (ERUS) because of the low amount of precipitation. The amount of PAH deposition showed clear seasonal variation and was high in winter and low in summer in downwind (South Korea, Japan) and oceanic-receptor regions. In the downwind region, the contributions from NCHN (WD 28-52%; DD 54-55%) and Central China (CCHN) (WD 43-65%; DD 33-38%) were large in winter, whereas self-contributions (WD 20-51%; DD 79-81%) were relatively high in summer. In the oceanic-receptor region, the deposition amount decreased with distance from the Asian continent. The amount of DD was strongly influenced by emissions from neighboring domains. The contributions of WD from NCHN (16-20%) and CCHN (28-35%) were large. The large contributions from China in summer to the downwind region were linked to vertical transport of PAHs over the Asian continent associated with convection.


Assuntos
Poluentes Atmosféricos , Monitoramento Ambiental , Ásia , China , Japão , República da Coreia , Federação Russa , Estações do Ano
3.
Environ Res Lett ; 12(12): 120201, 2017 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-30073034

RESUMO

A better understanding of land cover/land use changes (LCLUC) and their interactions with the atmospheric environment is essential for the sustainable management of natural resources, environmental protection, air quality, agricultural planning and food security. The 15 papers published in this focus issue showcase a variety of studies relating to drivers and impacts of LCLUC and air pollution in different South/Southeast Asian (S/SEA) countries. This synthesis article, in addition to giving context to the articles in this focus issue, also reviews the broad linkages between population, LCLUC and air pollution. Additionally, we identify knowledge gaps and research priorities that are essential in addressing air pollution issues in the region. We conclude that for effective pollution mitigation in S/SEA countries, quantifying drivers, sources and impacts of pollution need a thorough data analysis through ground-based instrumentation, models and integrated research approaches. We also stress the need for the development of sustainable technologies and strengthening the scientific and resource management communities through capacity building and training activities to address air pollution issues in S/SEA countries.

4.
J Environ Radioact ; 164: 1-12, 2016 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-27372443

RESUMO

The amount of 137Cs released by the Fukushima Dai-ichi Nuclear Power Plant accident of 11 March 2011 was inversely estimated by integrating an atmospheric dispersion model, an a priori source term, and map of deposition recorded by aircraft. An a posteriori source term refined finer (hourly) variations comparing with the a priori term, and estimated 137Cs released 11 March to 2 April to be 8.12 PBq. Although time series of the a posteriori source term was generally similar to those of the a priori source term, notable modifications were found in the periods when the a posteriori source term was well-constrained by the observations. Spatial pattern of 137Cs deposition with the a posteriori source term showed better agreement with the 137Cs deposition monitored by aircraft. The a posteriori source term increased 137Cs deposition in the Naka-dori region (the central part of Fukushima Prefecture) by 32.9%, and considerably improved the underestimated a priori 137Cs deposition. Observed values of deposition measured at 16 stations and surface atmospheric concentrations collected on a filter tape of suspended particulate matter were used for validation of the a posteriori results. A great improvement was found in surface atmospheric concentration on 15 March; the a posteriori source term reduced root mean square error, normalized mean error, and normalized mean bias by 13.4, 22.3, and 92.0% for the hourly values, respectively. However, limited improvements were observed in some periods and areas due to the difficulty in simulating accurate wind fields and the lack of the observational constraints.


Assuntos
Poluentes Radioativos do Ar/análise , Radioisótopos de Césio/análise , Acidente Nuclear de Fukushima , Modelos Teóricos , Monitoramento de Radiação/métodos , Aeronaves , Centrais Nucleares
5.
BMJ Open ; 6(2): e010410, 2016 Feb 25.
Artigo em Inglês | MEDLINE | ID: mdl-26916696

RESUMO

OBJECTIVES: There has been little study on the effect of traffic-related air pollution on the incidence and persistence of asthma in preschool children. We evaluated the association of exposure to traffic-related air pollution with the incidence/persistence of asthma during the first 3 years of life using a population-based study. METHODS: A baseline survey was conducted in 1½-year-old children (n=63,266). A follow-up survey at 3 years of age (n=43,343) identified new-onset asthma cases (n=853) and persistence of asthma (n=214). In the prevalence/persistence study, the outdoor concentrations of nitrogen oxides (NOx) and elemental carbon (EC) at home during the first 1½â€…years of life were estimated by a dispersion model. In the nested case-control study, which regarded incidence of asthma as cases, the personal exposure levels were estimated by dispersion model including time-activity pattern. RESULTS: There was no statistically significant association between the incidence of asthma between age 1½ and 3 years and personal exposure levels to NOx nor EC. However, the persistence of asthmatic symptoms (between 1½ and 3  ears) was significantly associated with outdoor concentrations of NOx. ORs for the persistence of asthmatic symptoms were 6.02 (95% CI 1.51 to 23.92) for the comparison between the upper 5th and lower 25th centiles of NOx. CONCLUSIONS: While no statistically significant association was observed for the incidence of asthma, the persistence of asthmatic symptoms in preschool children was significantly associated with traffic-related air pollution. This supports its importance as a risk factor in childhood airway disease.


Assuntos
Poluentes Atmosféricos/efeitos adversos , Poluição do Ar/efeitos adversos , Asma/epidemiologia , Emissões de Veículos , Estudos de Casos e Controles , Pré-Escolar , Monitoramento Ambiental/estatística & dados numéricos , Feminino , Humanos , Incidência , Japão/epidemiologia , Masculino , Fatores de Risco
6.
Int Arch Allergy Immunol ; 167(4): 253-63, 2015.
Artigo em Inglês | MEDLINE | ID: mdl-26426799

RESUMO

OBJECTIVE: This study clarified sensitization patterns to house dust mite (HDM) and Japanese cedar pollen (JCP) in Japanese lower-grade schoolchildren. We also explored factors associated with allergic sensitization. METHODS: This cross-sectional study used a database from the Study on Respiratory Disease and Automobile Exhaust (SORA), a Japanese health study project. The subjects comprised 8,815 pupils aged 6-9 years. We obtained the distribution of HDM- and JCP-specific IgE, respectively, as a marker of sensitization. To determine factors associated with sensitization, we used logistic regression and calculated adjusted odds ratios (AORs) for the relative prevalence of sensitization. The cut-off point for specific IgE levels was 0.35 kU/l. RESULTS: Sensitization to HDM and JCP was detected in 51 and 39% of subjects, respectively, occurring more often in boys and at older ages. In addition, AORs of sensitization to HDM/JCP were higher in subjects with a history of bronchitis, parental asthma, parental atopic eczema and parental pollinosis. In contrast, AORs for sensitization were lower in those subjected to maternal passive smoking as well as among boys with pets. AORs of sensitization to JCP alone were lower in those with a history of otitis media, those who had been bottle milk fed, and those who were not the firstborn and who lived near a busy road. CONCLUSION: Sensitization to HDM and JCP was detected in 51 and 39% of lower-grade schoolchildren, respectively.


Assuntos
Hipersensibilidade/etiologia , Rinite Alérgica Sazonal/etiologia , Alérgenos/imunologia , Animais , Especificidade de Anticorpos , Grupo com Ancestrais do Continente Asiático , Criança , Estudos Transversais , Cryptomeria/efeitos adversos , Cryptomeria/imunologia , Dermatophagoides pteronyssinus/imunologia , Feminino , Humanos , Hipersensibilidade/epidemiologia , Hipersensibilidade/imunologia , Imunoglobulina E/sangue , Japão/epidemiologia , Masculino , Razão de Chances , Pólen/efeitos adversos , Pólen/imunologia , Prevalência , Rinite Alérgica Sazonal/epidemiologia , Rinite Alérgica Sazonal/imunologia , Fatores de Risco
7.
Sci Rep ; 4: 6717, 2014 Oct 22.
Artigo em Inglês | MEDLINE | ID: mdl-25335435

RESUMO

No observed data have been found in the Fukushima Prefecture (FP) for the time-series of atmospheric radionuclides concentrations just after the Fukushima Daiichi Nuclear Power Plant (FD1NPP) accident. Accordingly, current estimates of internal radiation doses from inhalation, and atmospheric radionuclide concentrations by atmospheric transport models are highly uncertain. Here, we present a new method for retrieving the hourly atmospheric (137)Cs concentrations by measuring the radioactivity of suspended particulate matter (SPM) collected on filter tapes in SPM monitors which were operated even after the accident. This new dataset focused on the period of March 12-23, 2011 just after the accident, when massive radioactive materials were released from the FD1NPP to the atmosphere. Overall, 40 sites of the more than 400 sites in the air quality monitoring stations in eastern Japan were studied. For the first time, we show the spatio-temporal variation of atmospheric (137)Cs concentrations in the FP and the Tokyo Metropolitan Area (TMA) located more than 170 km southwest of the FD1NPP. The comprehensive dataset revealed how the polluted air masses were transported to the FP and TMA, and can be used to re-evaluate internal exposure, time-series radionuclides release rates, and atmospheric transport models.


Assuntos
Contaminação Radioativa do Ar , Acidente Nuclear de Fukushima , Radioisótopos/isolamento & purificação , Atmosfera , Humanos , Japão , Centrais Nucleares , Radioisótopos/toxicidade
9.
Environ Pollut ; 195: 236-44, 2014 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-25074425

RESUMO

In this study, the top-down NOx emissions estimated from satellite observations of NO2 vertical column densities over North Korea from 1996 to 2009 were analyzed. Also, a bottom-up NOx emission inventory from REAS 1.1 from 1980 to 2005 was analyzed with several statistics. REAS 1.1 was in good agreement with the top-down approach for both trend and amount. The characteristics of NOx emissions in North Korea were quite different from other developed countries including South Korea. In North Korea, emissions from industry sector was the highest followed by transportation sector in the 1980s. However, after 1990, the NOx emissions from other sector, mainly agriculture, became the 2nd highest. Also, no emission centers such as urban areas or industrial areas were distinctively observed. Finally, the monthly NOx emissions were high during the warm season.


Assuntos
Poluentes Atmosféricos/análise , Óxidos de Nitrogênio/análise , Poluição do Ar/estatística & dados numéricos , República Democrática Popular da Coreia , Indústrias , República da Coreia , Estações do Ano
10.
J Air Waste Manag Assoc ; 64(4): 374-87, 2014 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-24843910

RESUMO

UNLABELLED: Improvement of air quality models is required so that they can be utilized to design effective control strategies for fine particulate matter (PM2.5). The Community Multiscale Air Quality modeling system was applied to the Greater Tokyo Area of Japan in winter 2010 and summer 2011. The model results were compared with observed concentrations of PM2.5 sulfate (SO4(2-)), nitrate (NO3(-)) and ammonium, and gaseous nitric acid (HNO3) and ammonia (NH3). The model approximately reproduced PM2.5 SO4(2-) concentration, but clearly overestimated PM2.5 NO3(-) concentration, which was attributed to overestimation of production of ammonium nitrate (NH4NO3). This study conducted sensitivity analyses of factors associated with the model performance for PM2.5 NO3(-) concentration, including temperature and relative humidity, emission of nitrogen oxides, seasonal variation of NH3 emission, HNO3 and NH3 dry deposition velocities, and heterogeneous reaction probability of dinitrogen pentoxide. Change in NH3 emission directly affected NH3 concentration, and substantially affected NH4NO3 concentration. Higher dry deposition velocities of HNO3 and NH3 led to substantial reductions of concentrations of the gaseous species and NH4NO3. Because uncertainties in NH3 emission and dry deposition processes are probably large, these processes may be key factors for improvement of the model performance for PM2.5 NO3(-). IMPLICATIONS: The Community Multiscale Air Quality modeling system clearly overestimated the concentration of fine particulate nitrate in the Greater Tokyo Area of Japan, which was attributed to overestimation of production of ammonium nitrate. Sensitivity analyses were conducted for factors associated with the model performance for nitrate. Ammonia emission and dry deposition of nitric acid and ammonia may be key factors for improvement of the model performance.


Assuntos
Poluentes Atmosféricos/análise , Amônia/análise , Monitoramento Ambiental , Nitratos/análise , Ácido Nítrico/análise , Material Particulado/análise , Sulfatos/análise , Atmosfera/química , Umidade , Modelos Teóricos , Tamanho da Partícula , Estações do Ano , Temperatura Ambiente , Tóquio , Vento
11.
J Air Waste Manag Assoc ; 64(4): 436-44, 2014 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-24843914

RESUMO

UNLABELLED: NO2 vertical column densities (VCDs) over East Asia in June and December 2007 were simulated by the Community Multi-scale Air Quality (CMAQ) version 4.7.1 using an updated and more elaborate version of the Regional Emission Inventory in Asia (REAS) version 2. The modeling system could reasonably capture observed spatiotemporal changes of NO2 VCDs by satellite sensors, the Global Ozone Monitoring Experiment-2 (GOME-2), the Scanning Imaging Absorption Spectrometer for Atmospheric Cartography (SCIAMACHY), and the Ozone Monitoring Instrument (OMI), even at the coarsest horizontal resolution of 80 km. The CMAQ simulations were performed in a sequence of three horizontal resolutions (80 km, 40 km, and 20 km) for June and December 2007 to investigate the influence of changes of horizontal resolution on the obtained NO2 VCDs. CMAQ-simulated NO2 VCDs generally increased with improvements in resolution from 80 km to 40 km and then to 20 km. Increases in the CMAQ-simulated NO2 VCDs were greater for the change from 80 km to 40 km than for those from 40 km and 20 km, in which the increases of NO2 VCDs due to the improvement of horizontal resolution were approached convergence at the horizontal resolution of approximately 20 km. Conversely, no clear convergences in NO2 VCDs changes were found at near Tokyo and over the East China Sea. The biases of the NO2 VCDs simulated at a resolution of 20 km against the satellite retrievals were -36% near Beijing (CHN1) and -78% near Shanghai (CHN2) in summer; these errors were found to be comparable to the horizontal resolution-dependent errors, which were 18-25% at CHN1 and 44-58% at CHN2 from 80 km to 40 km. Conversely, the influence of changes of horizontal resolution in winter was relatively less compared to that in summer. IMPLICATIONS: NO2 VCDs over East Asia in June and December 2007 were simulated using CMAQ version 4.7.1 and REAS version 2. The modeling system could reasonably capture observed spatiotemporal changes of NO2 VCDs by satellite sensors. The CMAQ simulations were performed in a sequence of three horizontal resolutions, 80, 40, and 20 km, to investigate the influence of changes of horizontal resolution on the obtained NO2 VCDs. The results suggested that the influence of changes of horizontal resolution was larger in summer compared to that in winter. The magnitude of the influence was comparable to the biases of the NO2 VCDs simulated at a resolution of 20 km against the satellite retrievals.


Assuntos
Poluentes Atmosféricos/análise , Poluição do Ar/análise , Monitoramento Ambiental , Dióxido de Nitrogênio/análise , Ozônio/análise , Atmosfera/química , China , Extremo Oriente , Modelos Teóricos , Estações do Ano , Análise Espaço-Temporal
12.
J Air Waste Manag Assoc ; 64(4): 445-52, 2014 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-24843915

RESUMO

UNLABELLED: The authors analyze the sensitivities of source regions in East Asia to PM2.5 (particulate matter with an aerodynamic diameter of < or = 2.5 microm) concentration at Fukue Island located in the western part of Japan by using a regional chemical transport model with emission sensitivity simulations for the year 2010. The temporal variations in PM2.5 concentration are generally reproduced, but the absolute concentration is underestimated by the model. Chemical composition of PM2.5 in the model is compared with filter sampling data in spring; simulated sulfate, ammonium, and elemental carbon are consistent with observations, but mass concentration of particulate organic matters is underestimated. The relative contribution from each source region shows the seasonal variation, especially in summer. The contribution from central north China (105 degrees E-124 degrees E, 34 degrees N-42 degrees N) accounts for 50-60% of PM2.5 at Fukue Island except in summer; it significantly decreases in summer (18%). Central south China (105 degrees E-123 degrees E, 26 degrees N-34 degrees N) has the relative contribution of 15-30%. The contribution from the Korean Peninsula is estimated at about 10% except in summer. The domestic contribution accounts for about 7% in spring and autumn and increases to 19% in summer. We also estimate the relative contribution to daily average concentration in high PM2.5 days (> 35 microg m(-3)). Central north China has a significant contribution of 60-70% except in summer. The relative contribution from central south China is estimated at 46% in summer and about 30% in the other seasons. The contributions from central north and south China on high PM2.5 days are generally larger than those of their seasonal mean contributions. The domestic contribution is smaller than the seasonal mean value in every season; it is less than 10% even in summer. These model results suggest that foreign anthropogenic sources have a substantial impact on attainment of the atmospheric environmental standard of Japan at Fukue Island. IMPLICATIONS: The contribution from several source regions in East Asia to PM2.5 concentration at Fukue Island, a remote island located in the western part of Japan and close to the Asian continent, is estimated using a three-dimensional chemical transport model. The model results suggest that PM2.5 that is attributed to foreign anthropogenic sources have a larger contribution than that of domestic pollution and have a substantial impact on attainment of the atmospheric environmental standard of Japan at Fukue Island.


Assuntos
Poluentes Atmosféricos/análise , Compostos de Amônio/análise , Carbono/análise , Monitoramento Ambiental , Material Particulado/análise , Sulfatos/análise , Atmosfera/química , China , Extremo Oriente , Japão , Modelos Teóricos , Tamanho da Partícula , Estações do Ano , Análise Espaço-Temporal
13.
J Expo Sci Environ Epidemiol ; 24(4): 372-9, 2014 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-24619296

RESUMO

Air pollution is widely understood to be capable of exacerbating asthma symptoms. Here we examined the association between traffic-related air pollution and development of asthma in school children. Subjects were 10,069 school children in their first through third years of compulsory education (6-9-year old). The main outcome was incidence of asthma as determined from the questionnaire. Follow-up surveys were conducted every year up to 4 years after the end of the study. To evaluate individual level of exposure to traffic-related air pollution, we used a simulation model that accounted for exposure level both at home and at school. As surrogates of traffic-related air pollution, the estimation target was the annual average individual exposure of automobile exhaust-originating nitrogen oxides (NOx) and elemental carbon (EC). Confounding factors were adjusted using a discrete-time logistic regression model. We found a positive association between exposure to EC and incidence of asthma. The odds ratio (OR) (95% confidence interval) for asthma incidence was 1.07 (1.01-1.14) for each 0.1 µg/m(3) EC and 1.01 (0.99-1.03) for each 1 p.p.b. NOx. Traffic-related air pollution is associated with development of asthma in school children.


Assuntos
Poluentes Atmosféricos/toxicidade , Asma/induzido quimicamente , Exposição Ambiental , Emissões de Veículos , Asma/epidemiologia , Criança , Estudos de Coortes , Humanos , Japão/epidemiologia , Estudos Prospectivos
14.
Environ Pollut ; 182: 324-34, 2013 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-23973884

RESUMO

We analyzed the source-receptor relationships for particulate polycyclic aromatic hydrocarbon (PAH) concentrations in northeastern Asia using an aerosol chemical transport model. The model successfully simulated the observed concentrations. In Beijing (China) benzo[a]pyren (BaP) concentrations are due to emissions from its own domain. In Noto, Oki and Tsushima (Japan), transboundary transport from northern China (>40 °N, 40-60%) and central China (30-40 °N, 10-40%) largely influences BaP concentrations from winter to spring, whereas the relative contribution from central China is dominant (90%) in Hedo. In the summer, the contribution from Japanese domestic sources increases (40-80%) at the 4 sites. Contributions from Japan and Russia are additional source of BaP over the northwestern Pacific Ocean in summer. The contribution rates for the concentrations from each domain are different among PAH species depending on their particulate phase oxidation rates. Reaction with O3 on particulate surfaces may be an important component of the PAH oxidation processes.


Assuntos
Poluentes Atmosféricos/análise , Monitoramento Ambiental , Hidrocarbonetos Policíclicos Aromáticos/análise , Poluição do Ar/estatística & dados numéricos , Ásia , Modelos Químicos , Material Particulado/análise
15.
J Expo Sci Environ Epidemiol ; 23(5): 487-97, 2013.
Artigo em Inglês | MEDLINE | ID: mdl-23715083

RESUMO

We developed an exposure estimation model for an epidemiological study on the effect of traffic-related air pollutants on respiratory diseases. The model estimates annual average outdoor concentration of nitrogen oxides (NOx) and elemental carbon (EC). The model is composed of three nested plume dispersion type submodels treating different spatial scales from a few meters to tens of kilometers. The emissions from road traffic was estimated at high spatial resolution along the paths of roads taking into account the effects of individual building shape and traffic signals to secure accuracy near trunk roads where most of the subjects of the epidemiological study resided. Model performance was confirmed by field measurements at permanent local government stations and purpose-built temporary stations; the latter supplemented roadside monitoring points and provided EC concentrations, which are not measured routinely. We infer that EC emissions were underestimated by using the available database because there were significant contributions to EC concentrations from sources that did not emit much NOx. An adjustment concentration yielded good agreement between model estimates and field measurements.


Assuntos
Poluição do Ar , Exposição Ambiental , Modelos Teóricos , Emissões de Veículos , Humanos , Japão
16.
Environ Sci Technol ; 47(5): 2314-22, 2013 Mar 05.
Artigo em Inglês | MEDLINE | ID: mdl-23391028

RESUMO

Chemical transport models played key roles in understanding the atmospheric behaviors and deposition patterns of radioactive materials emitted from the Fukushima Daiichi nuclear power plant after the nuclear accident that accompanied the great Tohoku earthquake and tsunami on 11 March 2011. However, model results could not be sufficiently evaluated because of limited observational data. We assess the model performance to simulate the deposition patterns of radiocesium ((137)Cs) by making use of airborne monitoring survey data for the first time. We conducted ten sensitivity simulations to evaluate the atmospheric model uncertainties associated with key model settings including emission data and wet deposition modules. We found that simulation using emissions estimated with a regional-scale (∼ 500 km) model better reproduced the observed (137)Cs deposition pattern in eastern Japan than simulation using emissions estimated with local-scale (∼ 50 km) or global-scale models. In addition, simulation using a process-based wet deposition module reproduced the observations well, whereas simulation using scavenging coefficients showed large uncertainties associated with empirical parameters. The best-available simulation reproduced the observed (137)Cs deposition rates in high-deposition areas (≥ 10 kBq m(-2)) within 1 order of magnitude and showed that deposition of radiocesium over land occurred predominantly during 15-16, 20-23, and 30-31 March 2011.


Assuntos
Radioisótopos de Césio/análise , Acidente Nuclear de Fukushima , Modelos Teóricos , Monitoramento de Radiação , Simulação por Computador , Japão
17.
Environ Sci Technol ; 46(9): 4941-9, 2012 May 01.
Artigo em Inglês | MEDLINE | ID: mdl-22435795

RESUMO

The emission, concentration levels, and transboundary transport of particulate polycyclic aromatic hydrocarbons (PAHs) in Northeast Asia were investigated using particulate PAH measurements, the newly developed emission inventory (Regional Emission inventory in ASia for Persistent Organic Pollutants version, REAS-POP), and the chemical transport model (Regional Air Quality Model ver2 for POPs version, RAQM2-POP). The simulated concentrations of the nine particulate PAHs agreed well with the measured concentrations, and the results firmly established the efficacy of REAS/RAQM2-POP. It was found that the PAH concentrations in Beijing (China, source region), which were emitted predominantly from domestic coal, domestic biofuel, and other transformations of coal (including coke production), were approximately 2 orders of magnitude greater than those monitored at Noto (Japan, leeward region). In Noto, the PAH concentrations showed seasonal variations; the PAH concentrations were high from winter to spring due to contributions from domestic coal, domestic biofuel, and other transformations of coal, and low in summer. In summer, these contribution were decrease, instead, other sources, such as the on-road mobile source, were relatively increased compared with those in winter. These seasonal variations were due to seasonal variations in emissions from China, as well as transboundary transport across the Asian continent associated with meteorological conditions.


Assuntos
Poluição do Ar/análise , Atmosfera/análise , Material Particulado/análise , Hidrocarbonetos Policíclicos Aromáticos/análise , Simulação por Computador , Extremo Oriente , Modelos Teóricos , Estações do Ano , Incerteza
18.
Environ Sci Technol ; 45(16): 6784-92, 2011 Aug 15.
Artigo em Inglês | MEDLINE | ID: mdl-21780739

RESUMO

The radiocarbon ((14)C) of total carbon (TC) in atmospheric fine particles was measured at 6 h or 12 h intervals at two sites, 50 and 100 km downwind from Tokyo, Japan (Kisai and Maebashi) in summer 2007. The percent modern carbon (pMC) showed clear diurnal variations with minimums in the daytime. The mean pMC values at Maebashi were 28 ± 7 in the daytime and 45 ± 16 at night (37 ± 15 for the overall period). Those at Kisai were 26 ± 9 in the daytime and 44 ± 8 at night (37 ± 12 for the overall period). This data indicates that fossil sources were major contributors to the daytime TC, while fossil and modern sources had comparable contributions to nighttime TC in the suburban areas. At both sites, the concentration of fossil carbon as well as O(3) and the estimated secondary organic carbon increased in the daytime. These results suggest that fossil sources around Tokyo contributed significantly to the high daytime concentration of secondary organic aerosols (SOA) at the two suburban sites. A comparison of pMC and the ratio of elemental carbon/TC from our particulate samples with those from three end-member sources corroborates the dominant role of fossil SOA in the daytime.


Assuntos
Movimentos do Ar , Ritmo Circadiano , Material Particulado/análise , Estações do Ano , Carbono/análise , Radioisótopos de Carbono , Fósseis , Compostos Orgânicos/análise , Ozônio/análise , Tóquio
19.
Environ Sci Technol ; 44(22): 8581-86, 2010 Nov 15.
Artigo em Inglês | MEDLINE | ID: mdl-20886860

RESUMO

Diurnal variations of fossil secondary organic carbon (SOC) and nonfossil SOC were determined for the first time using a combination of several carbonaceous aerosol measurement techniques, including radiocarbon (¹4C) determinations by accelerator mass spectrometry, and a receptor model (chemical mass balance, CMB) at a site downwind of Tokyo during the summer of 2007. Fossil SOC showed distinct diurnal variation with a maximum during daytime, whereas diurnal variation of nonfossil SOC was relatively small. This behavior was reproduced by a chemical transport model (CTM). However, the CTM underestimated the concentration of anthropogenic secondary organic aerosol (ASOA) by a factor of 4-7, suggesting that ASOA enhancement during daytime is not explained by production from volatile organic compounds that are traditionally considered major ASOA precursors. This result suggests that unidentified semivolatile organic compounds or multiphase chemistry may contribute largely to ASOA production. As our knowledge of production pathways of secondary organic aerosol (SOA) is still limited, diurnal variations of fossil and nonfossil SOC in our estimate give an important experimental constraint for future development of SOA models.


Assuntos
Aerossóis/análise , Poluentes Atmosféricos/análise , Carbono/análise , Combustíveis Fósseis/análise , Aerossóis/química , Movimentos do Ar , Poluentes Atmosféricos/química , Carbono/química , Ritmo Circadiano , Cidades , Monitoramento Ambiental/métodos , Japão , Cinética , Modelos Químicos
SELEÇÃO DE REFERÊNCIAS
DETALHE DA PESQUISA