Kubota, Tomohiro; Kuroda, Hisao*; Watanabe, Mirai*; Takahashi, Akiko*; Nakazato, Ryoji*; Tarui, Mika*; Matsumoto, Shunichi*; Nakagawa, Keita*; Numata, Yasuko*; Ouchi, Takao*; et al.
Atmospheric Environment, 243, p.117856_1 - 117856_9, 2020/12
The dry and wet depositions of atmospheric ammonia (NH) is one of the important pathways of nitrogen loads to aquatic ecosystems. Crop and livestock agriculture, one of the largest emitters of NH in Asian countries, are known to cause high spatial and seasonal variation of NH and influence the surrounding lake basin areas via its dry and wet deposition. However, the spatial characteristics of the NH concentration in basin scale are not completely understood for regulation in NH emission. Here we aim to clarify dominant factors of spatial and seasonal variations of the NH concentration in a eutrophic lake basin surrounded by agricultural areas in Japan. Passive sampling over various land use categories in the basin was conducted at 36 sites in total from October 2018 to January 2020. Interestingly, the observed NH concentration near the livestock houses were higher in winter than summer, which was inconsistent with knowledge of seasonal changes of current NH emission inventory based on temperature-driven volatilization process. Comparing monthly NH concentrations with various meteorological factors, we suggested the importance of seasonal advection of NH from high emission sources to which has been rarely paid attention by the previous past studies. As for this, should be considered for lake ecosystem management since deposition of NH is known to be closely related to the ecological processes such as phytoplankton blooming.
Kadowaki, Masanao; Terada, Hiroaki; Nagai, Haruyasu
Atmospheric Environment; X (Internet), 8, p.100098_1 - 100098_17, 2020/12
The behaviors of atmospheric I and the global cycle of I remain incompletely understood because the spatiotemporal resolution of monitoring is insufficient and few measurement-based models have been reported. This study aims to quantitatively understand the global budget of I. When quantifying, we conduct global atmospheric I dispersion simulations covering from 2007 to 2010. To achieve this goal, the present study newly incorporated the iodine chemistry processes of two gas-phase chemical reactions, six photolysis reactions, and two heterogeneous reactions into an existing atmospheric I transport model (GEARN-FDM). Besides the aerial release of I from nuclear fuel reprocessing facilities, the model includes the volatilization processes of I compounds from Earth's surface. The net I exchange fluxes from the atmosphere to the Earth's surface of land and ocean were estimated as 18.0 GBq/y and 5.3 GBq/y, respectively. The global I emission from oceans was estimated as 7.2 GBq/y, nearly half of the emission totals were emitted from the English Channel (3.2 GBq/y). In addition, the global I emission from land was estimated as 1.7 GBq/y. The remarkable I emission from land was mainly appeared in Europe, Russia, and North America, and the emission distribution is impacted by the activities of the past and ongoing nuclear fuel reprocessing facilities. The total I emission from ocean and land is lower than the I emission from the model-included nuclear fuel reprocessing facilities (23.3 GBq/y), showing that the aerial release of nuclear fuel reprocessing facilities in operation is still an important I source.
Sato, Yosuke*; Sekiyama, Tsuyoshi*; Fang, S.*; Kajino, Mizuo*; Qurel, A.*; Qulo, D.*; Kondo, Hiroaki*; Terada, Hiroaki; Kadowaki, Masanao; Takigawa, Masayuki*; et al.
Atmospheric Environment; X (Internet), 7, p.100086_1 - 100086_12, 2020/10
The third model intercomparison project for investigating the atmospheric behavior of Cs emitted during the Fukushima Daiichi Nuclear Power Plant (FDNPP) accident (FDNPP-MIP) was conducted. A finer horizontal grid spacing (1 km) was used than in the previous FDNPP-MIP. Nine of the models used in the previous FDNPP-MIP were also used, and all models used identical source terms and meteorological fields. Our analyses indicated that most of the observed high atmospheric Cs concentrations were well simulated, and the good performance of some models improved the performance of the multi-model ensemble. The analyses also confirmed that the use of a finer grid resolution resulted in the meteorological field near FDNPP being better reproduced. The good representation of the wind field resulted in the reasonable simulation of the narrow distribution of high deposition amount to the northwest of FDNPP and the reduction of the overestimation over the area to the south of FDNPP. In contrast, the performance of the models in simulating plumes observed over the Nakadori area, the northern part of Gunma, and the Tokyo metropolitan area was slightly worse.
Iwasaki, Toshiki*; Sekiyama, Tsuyoshi*; Nakajima, Teruyuki*; Watanabe, Akira*; Suzuki, Yasushi*; Kondo, Hiroaki*; Morino, Yu*; Terada, Hiroaki; Nagai, Haruyasu; Takigawa, Masayuki*; et al.
Atmospheric Environment, 214, p.116830_1 - 116830_11, 2019/10
The utilization of numerical atmospheric dispersion prediction (NDP) models for accidental discharge of radioactive substances was recommended by a working group of the Meteorological Society of Japan. This paper is to validate the recommendation through NDP model intercomparison in the accidental release from the Fukushima Dai-ichi Nuclear Power Plant in 2011. Emission intensity is assumed to be constant during the whole forecast period for the worst-case scenario unless time sequence of emission is available. We expect to utilize forecasts of surface air contaminations for preventions of inhalations of radioactive substances, and column-integrated amounts for mitigation of radiation exposure associated with wet deposition. Although NDP forecasts have ensemble spread, they commonly figure out relative risk in space and time. They are of great benefit to disseminating effective warnings to public without failure. The multi-model ensemble technique may be effective to improve the reliability.
Kadowaki, Masanao; Katata, Genki*; Terada, Hiroaki; Suzuki, Takashi; Hasegawa, Hidenao*; Akata, Naofumi*; Kakiuchi, Hideki*
Atmospheric Environment, 184, p.278 - 291, 2018/07
The long-lived radioactive iodine (I) is a useful geochemical tracer in the atmospheric environment. We recently observed clear seasonal trends in air concentration and deposition of I in Japan. Using these data, we developed a global atmospheric I transport model to reveal key processes for the global atmospheric I cycle. The model generally reproduced the observed seasonal change in air concentration and deposition of I in Japan, and the global distribution of I concentration in rain as presented in past literature. Numerical experiments changing the intensity of anthropogenic and natural sources were conducted to quantify the impact of anthropogenic sources on the global I cycle. The results indicated that the atmospheric I from the anthropogenic sources was deposited in winter and can be accumulated mainly in the northern part of Eurasia. In contrast, the atmospheric I from the natural sources dominated the deposition in summer. These results suggested that the re-emission process of I from the Earth's surface may be important as a secondary impact of I in the global-scaled environment. Furthermore, although wet deposition dominated the total deposition in the Northern hemisphere, dry deposition regionally and seasonally contributed to the total deposition over arctic and northern part of Eurasia in winter, suggesting that the dry deposition may play a key role in the seasonal change of I deposition in the Northern hemisphere high latitudes.
Katata, Genki; Kajino, Mizuo*; Matsuda, Kazuhide*; Takahashi, Akira*; Nakaya, Ko*
Atmospheric Environment, 97, p.501 - 510, 2014/11
To investigate the impact of hygroscopic growth on dry deposition onto forest canopies, numerical simulations of PM2.5 sulfate deposition using a multi-layer atmosphere-SOiL-VEGetation model (SOLVEG) ware performed. The scheme of particle dry deposition in SOLVEG was extended for application to a broad-leaved forest. An aerosol hygroscopic model based on the widely used -Khler theory was incorporated into the model to calculate water uptake by the aerosols. The model accurately reproduced essential turbulent exchange fluxes (momentum, heat, and water vapor) over the canopies and the soil temperature and moisture for a deciduous broad-leaved forest in central Japan. Temporal variations in the measured PM2.5 sulfate deposition velocity were generally reproduced by the model. By considering an increase in particle diameter due to hygroscopic growth, the prediction accuracy of the modeled deposition velocity under humid conditions was improved. Numerical experiments for varying aerosol size distributions and hygroscopic properties showed that the geometric mean diameter and hygroscopicity of particles have a large influence on hygroscopic growth levels. The results also suggested that the deposition velocity of wet particles increased due to hygroscopic growth when the relative humidity (RH) was approximately 50%, and that the velocity reached five times greater than that under dry conditions when RH exceeded 95%.
Katata, Genki; Yamaguchi, Takashi*; Sato, Haruna*; Watanabe, Yoko*; Noguchi, Izumi*; Hara, Hiroshi*; Nagai, Haruyasu
Asian Journal of Atmospheric Environment, 7(1), p.17 - 24, 2013/03
Fog deposition onto the cool-temperate deciduous forest in northern Japan was estimated by the inferential method using the parameterizations of deposition velocity and liquid water content of fog (LWC). Two parameterizations of fog deposition velocity derived from the field experiments and numerical simulations were tested. The empirical function between horizontal visibility (VIS) and LWC was applied to produce hourly LWC as input data of the inferential method. Weekly mean LWC computed from VIS had a good correlation with the one sampled by an active string-fog collector. Fog deposition calculated by the inferential method agreed with that computed from thorough fall data within the factors of 2 to 3. The results indicated that the inferential method using the current parameterizations of deposition velocity and LWC can provide a rough estimation of water input due to fog deposition onto cool-temperature deciduous forests.
Yamaguchi, Takashi*; Noguchi, Izumi*; Watanabe, Yoko*; Katata, Genki; Sato, Haruna*; Hara, Hiroshi*
Asian Journal of Atmospheric Environment, 7(1), p.8 - 16, 2013/03
Fog water chemistry was measured and the fog water deposition rate was estimated by a throughfall method at Lake Mashu, northern Japan, from May to November, 2010. NH and SO were the most abundant cation and anion, respectively. The fog water pH ranged from 4.2 to 6.4 (mean value: 5.1). The [NH]/[SO] equivalent ratio in fog water was more than 1.0 throughout the measuring period, indicating that NH was the major factor in the neutralization of fog water. The estimated fog water deposition rate and fog water deposition were 0.110.22 mm h and 117.0 mm, respectively. The estimated seasonal deposition of nitrogen in fog water, 26.1 meq m, was considerable amount compared to that of reported nitrogen deposition in rainfall.
Watanabe, Yoko*; Yamaguchi, Takashi*; Katata, Genki; Noguchi, Izumi*
Asian Journal of Atmospheric Environment, 7(1), p.1 - 7, 2013/03
SEM-EDX analysis was performed using birch leaves collected from urban area and suburb area in northern Japan. Collected leaves were divided into three treatments: (1) untreated, (2) wash leaf surface (adaxial side) with deionized water, and (3) wipe leaf surface with Kimwipes. In untreated samples, many various-shaped particles including soil particles and organic debris were deposited on the surface. Sulfur (S) particles were observed on the surface of samples collected from urban area. After treatments of (2), soil particles and S particles were washed off by water, although coarse particles still remained on the leaf surface. Although treatment of (3) removed almost all particles from surface, NaCl particles were found in both urban area and suburb area. Our study revealed that the behavior of particles depends on environmental conditions such as rain.
Takeyasu, Masanori; Takeishi, Minoru
Asian Journal of Atmospheric Environment, 4(1), p.20 - 25, 2010/06
The atmospheric Rn concentration in rain clouds was estimated by using the wet scavenging model of its decay products with the observed data of the environmental radiation. The origin of the Rn was also discussed, when a large increase of the radiation was observed. The estimation was done for a rainfall event on Dec. 26-27, 2003, when a large increase of the radiation was observed in Tokai-mura in Ibaraki, Japan. From a backward trajectory analysis, the origin of Rn atoms for that event was back-tracked to the northeastern part of China, and it was expected that the large amount of Rn exhalated in the northeastern part of China was transported to Tokai-mura by the Eurasian continental air mass.
Furuno, Akiko; Terada, Hiroaki; Chino, Masamichi; Yamazawa, Hiromi*
Atmospheric Environment, 38(40), p.6989 - 6998, 2004/12
We have been developing the computer-based emergency response system WSPEEDI which predicts long-range atmospheric dispersion of radionuclides discharged into the atmosphere due to a nuclear accident. The first version of WSPEEDI has a shortage that the spatial and temporal variation of the atmospheric boundary layer was very simply parameterized. Therefore we have developed the new version accomplished with the atmospheric dynamic model, in which the turbulent diffusivity in the mixing layer is calculated with a turbulence closure model. This paper describes the results of performance evaluation of the new version of WSPEEDI by comparing the simulation results with the European Tracer Experiment data. As a result of the verification, it was shown that the increase in the horizontal resolution largely improved the accuracy of the model prediction. The use of the turbulence closure model instead of the simple parameterization largely contributed to improve reproducibility of horizontal distribution of plumes.
Terada, Hiroaki; Ueda, Hiromasa*; Wang, Z.*
Atmospheric Environment, 36(3), p.503 - 509, 2002/01
Acid rain and its neutralization by yellow-sand in East Asia was investigated numerically by an Air Quality Prediction Modeling System (AQPMS). AQPMS consists of advection, diffusion, dry and wet deposition, gas- and liquid-phase chemistry. A new deflation module of the yellow-sand was designed to provide explicit information on the dust loading, and linked to the AQPMS. For model validation, the predicted pH values and sulfate- and nitrate-ion levels of precipitation, together with the surface concentrations of gaseous pollutants, were compared with measured values at atmospheric monitoring stations, and a reasonable agreement was obtained. Firstly, trend of the acid rain in East Asia due to the rapid increase of Chinese pollutants emission was investigated, and a remarkably rapid increase of acid rain area was predicted in the period from 1985 to 1995. Secondly, the simulation results of April 1995 exhibited a strong neutralization of the precipitation by the yellow-sand.
Yamazawa, Hiromi; Furuno, Akiko; Chino, Masamichi
Atmospheric Environment, 32(24), p.4343 - 4349, 1998/00
no abstracts in English
*; *; Amano, Hikaru; Ueno, Takashi; Sukhoruchkin, A. K.*; S.V.Kazakov*
Atmospheric Environment, 32(14-15), p.2587 - 2594, 1998/00
no abstracts in English