Using an hourly-resolution time series of the Fukushima radionuclides collected on used filter-tapes installed in suspended particulate matter (SPM) monitors, we measured the hourly radiocesium ...values at the SPM monitoring sites of Futaba and Naraha located within 20 km of the Fukushima Daiichi Nuclear Power Plant (FD1NPP) during March 12–25, 2011. The time-series of the 137Cs concentrations at the sites were analyzed and compared with radiation dose rates at the many monitoring posts/points of Fukushima Prefecture and the Tokyo Electric Power Company. At Futaba, nine plumes of high 137Cs concentrations were found on March 12–13, 15–16, 18–20, and 24–25, 2011, when southeasterly winds prevailed. On March 12, the first peak of the 137Cs concentrations was detected at Futaba at 9:00 Japanese Standard Time (JST) due to the first release from reactor Unit 1 (U1) in the early morning. Furthermore, the highest 137Cs concentration, i.e., 13,600 Bq m–3 was observed at 15:00 JST after a vent operation at U1, just before the hydrogen explosion of U1 at 15:36 JST. On the afternoon of March 15, plumes from the FD1NPP were observed at Futaba due to a constant southeasterly wind and were then transported to downwind, resulting in the formation of a highly deposited zone of radionuclides spanning more than 30 km from near the FD1NPP to the northwest. In contrast, seven plumes of high 137Cs concentrations were found at Naraha on March 15–16, 18, 20–21, 2011, when northerly winds prevailed. On March 15, a plume caused by the first release from Unit 2 was observed at Naraha at 1:00 JST, and the highest concentration, i.e., 8,300 Bq m–3, was observed at 3:00 JST, and then were transported southward to the Kantou area. The activity ratios of 134Cs/137Cs in the plumes were divided into two groups. The plumes at Futaba on March 12–13, which had ratios of 0.92–0.94, are identified to be released from U1, compared to its ratio of 0.94, as derived from the inventory data. All other plumes with the ratios of 1.02–1.04 at Futaba and Naraha during March 15–21 have not been determined to be released from U2 and/or Unit 3.
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.
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IJS, KILJ, NUK, PNG, UL, UM
There is substantial difference in the coal consumption data in China during 1996–2003 among the three official energy statistics; the province-by-province data in the China Energy Statistics ...Yearbook (PBP-CESY), the energy balance tables by International Energy Agency (IEA2004) 2004, Energy Statistics of Non-OECD Countries. IEA, Paris, and the country-total data in the China Energy Statistics Yearbook (CT-CESY). Verification of these data was made by GOME satellite observational data for tropospheric NO
2 column density in Northern China Plain reported by Irie et al. 2005, Evaluation of long-termtropospheric NO
2 data obtained by GOME over East Asia in 1996–2002. Geophysical Research Letter 32(11), L11810, doi: 10.1029/2005GL022770 and Richter et al. 2005, Increase in tropospheric nitrogen dioxide over China observed from space. Nature 437, 129–130. The NO
2 column increase from 1996 to 2002 averaged for the two reports is about 50%, whereas the NO
x
emission increases based on the PBP-CESY and IEA2004 are 25% and 15%, respectively, and that for CT-CESY is even lower. The discrepancy of the increasing trends between the satellite data and the PBP-CESY emission inventory could be within the uncertainty level with a reservation that the increase in total fuel consumption in PBP-CESY may still be underestimated particularly after the year of 1999. The increasing rates of NO
x
emissions during 1996–2002 calculated by using the IEA2004 and CT-CESY statistics are apparently underestimated beyond the uncertainty level of the satellite observation, and they are recommended not to be used for emission inventory studies in China during the period.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK
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.
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DOBA, EMUNI, FIS, FZAB, GEOZS, GIS, IJS, IMTLJ, IZUM, KILJ, KISLJ, MFDPS, NLZOH, NUK, OILJ, PILJ, PNG, SAZU, SBCE, SBJE, SBMB, SBNM, UILJ, UKNU, UL, UM, UPUK, VKSCE, ZAGLJ
We found a significant geographic gradient (longitudinal and latitudinal) in the sulfate (SO
4
2−) concentrations measured at multiple sites over the East Asian Pacific Rim region. Furthermore, the ...observed gradient was well reproduced by a regional chemical transport model. The observed and modeled SO
4
2− concentrations were higher at the sites closer to the Asian continent. The concentrations of SO
4
2− from China as calculated by the model also showed the fundamental features of the longitudinal/latitudinal gradient. The proportional contribution of Chinese SO
4
2− to the total in Japan throughout the year was above 50–70% in the control case, using data for Chinese sulfur dioxide (SO
2) emission from the Regional Emission Inventory in Asia (40–60% in the low Chinese emissions case, using Chinese SO
2 emissions data from the State Environmental Protection Administration of China), with a winter maximum of approximately 65–80%, although the actual concentrations of SO
4
2− from China were highest in summer. The multiple-site measurements and the model analysis strongly suggest that the SO
4
2− concentrations in Japan were influenced by the outflow from the Asian continent, and this influence was greatest in the areas closer to the Asian continent. In contrast, we found no longitudinal/latitudinal gradient in SO
2 concentrations; instead SO
2 concentrations were significantly correlated with local SO
2 emissions. Our results show that large amounts of particulate sulfate are transported over long distances from the East Asian Pacific Rim region, and consequently the SO
4
2− concentrations in Japan are controlled by the transboundary outflow from the Asian continent.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK
The authors analyze the sensitivities of source regions in East Asia to PM
2.5
(particulate matter with an aerodynamic diameter of ≤2.5 µm) 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 PM
2.5
concentration are generally reproduced, but the absolute concentration is underestimated by the model. Chemical composition of PM
2.5
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°E-124°E, 34°N-42°N) accounts for 50-60% of PM
2.5
at Fukue Island except in summer; it significantly decreases in summer (18%). Central south China (105°E-123°E, 26°N-34°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 PM
2.5
days (>35 μg 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 PM
2.5
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 PM
2.5
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 PM
2.5
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.
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BFBNIB, GIS, IJS, KISLJ, NUK, PNG, UL, UM, UPUK
Sulfate aerosols simulated by an aerosol module coupled to the Nonhydrostatic Icosahedral Atmospheric Model (NICAM) at a spatial resolution (220 km) widely used by global climate models were ...evaluated by a comparison with in situ observations and the same aerosol module coupled to the Model for Interdisciplinary Research on Climate (MIROC) over East Asia for January, April, July, and October 2006. The results indicated that a horizontal gradient of sulfate from the source over China to the outflow over Korea‐Japan was present in both the simulations and the observations. At the observation sites, the correlation coefficients of the sulfate concentrations between the simulations and the observations were high (NICAM: 0.49–0.89, MIROC: 0.61–0.77), whereas the simulated sulfate concentrations were lower than those obtained by the observation with the normalized mean bias of NICAM being −68 to −54% (all), −77 to −63% (source), and −67 to −30% (outflow) and that of MIROC being −61 to −28% (all), −77 to −63% (source), and −60 to +2% (outflow). Both NICAM and MIROC strongly underpredict surface SO2 over China source regions and Korea‐Japan outflow regions, but the MIROC SO2 is much higher than NICAM SO2 over both regions. These differences between the models were mainly explained by differences in the sulfate formation within clouds and the dry deposition of SO2. These results indicated that the uncertainty of the meteorological and cloud fields as well as the vertical transport patterns between the different host climate models has a substantial impact on the simulated sulfate distribution.
Key Points
Sulfate aerosols and SO2 over East Asia are simulated by two global models
An intercomparison with the same aerosol/chemistry module is conducted
Lower level clouds and vertical transport strongly affect sulfur distribution
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BFBNIB, FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SBCE, SBMB, UL, UM, UPUK
Present and future tropospheric ozone (O3) concentrations over east Asia have been simulated by the Models‐3 Community Multiscale Air Quality Modeling System (CMAQ) coupled with the Regional Emission ...Inventory in Asia (REAS) to predict surface O3 variations caused by future anthropogenic emissions changes. For future prediction, REAS provides three emission scenarios for China (the reference (REF), the policy succeed case (PSC), and the policy failure case (PFC) scenarios) and one emission scenario (the REF scenario) for the other countries. Simulated O3 concentration in summer was relatively high (70–80 ppbv in June and 65–75 ppbv in August) over the North China Plain in 2000. The projected REF emissions for 2020 (2020REF) enhance the monthly averaged O3 to 75–90 ppbv in June and 75–85 ppbv in August. The projected PSC emissions for 2020 (2020PFC), including a slight NOx reduction of –0.2 Tg (–2%) and a large NMVOC increase of 14.3 Tg (97%) for total Chinese emissions during 2000–2020, cause the monthly and annually averaged O3 concentrations to decrease by less than 2 ppbv in northeastern and central China. Over the North China Plain, the projected PFC emissions for 2020 (2020PFC) cause significant increases, more than 20 ppbv in the monthly averaged O3, and the O3 will be 85–105 ppbv in June and 80–95 ppbv in August for 2020. The 2020PFC also affect O3 increases in early summer in South Korea (14–18 ppbv increase for monthly average) and Japan (2–14 ppbv increase for monthly average) during 2000–2020 despite the slight NOx increase of 0.4 Tg (25%) in South Korea and the slight NOx reduction of –0.2 Tg (–10%) in Japan during 2000–2020. The pollutant in these regions seems to be transport from upwind source regions. These experiments show that over central eastern China at midday in June, the O3 concentration is largely affected by NOx emission increases but is insensitive to NMVOC emission increases.
In this study, the emission inventories of NOx, which is a major air pollutant of South Korea were compared and analyzed. The two bottom-up emission inventories, Clean Air Policy Support System ...(CAPSS) and Regional Emission inventory in ASia (REAS), which are the latest emission inventories about the air pollutant emissions about South Korea were compared to find out the trend of NOx emission during 1996–2005. Also, these two emission inventories were compared with the top down NOx emissions estimated from satellite observations to validate the amount of NOx emitted from South Korea. The total NOx emission trends, sectoral and regional comparisons were carried out. The trend of the top down estimated NOx emission was similar to CAPSS and REAS. However, the magnitudes of the top down estimated NOx emission were usually closer to those of CAPSS than those of REAS. The NOx emissions from transportation sector of REAS were larger than that of CAPSS, and this corresponded to the difference of total amount of NOx emission between CAPSS and REAS. By comparing the differences of the ratios of the vehicle kilometers traveled (VKT) and emission factors (EFs), it was identified that most of the difference between CAPSS and REAS was due to these factors for diesel vehicles in REAS. Implications of this higher VKT values in REAS were discussed.
•Two bottom-up emission inventories (CAPSS and REAS) for NOx were compared.•CAPSS and REAS were compared with the top down NOx emissions as the reference value.•The magnitudes of the top down estimated NOx emission were closer to CAPSS.•CAPSS seems to be more reliable to estimate the NOx emission of South Korea.•The difference between CAPSS and REAS was due to VKT and EFs for diesel vehicles.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK
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