Mass balance and latest fluxes of radiocesium derived from the fukushima accident in the western North Pacific Ocean and coastal regions of Japan

This article summarizes and discusses mass balance calculations of the activities of Fukushima-derived 137Cs released to the atmosphere and ocean prior to 2018 as well as the 137Cs inventories on land and in the ocean, biota, and sediment. We propose that the consensus value of the total amount of 137Cs released to the atmosphere was 15–21 PBq; atmospheric deposition of 137Cs on land was 3–6 PBq; atmospheric deposition of 137Cs on the North Pacific was 12–15 PBq; and direct discharge of 137Cs to the ocean was 3–6 PBq. We also evaluated the movement of 137Cs from one domain to another for several years after the accident. We calculated that the amount of 137Cs transported by rivers might be 40 TBq. The annual deposition of 137Cs due to resuspension at Okuma during the period 2014–2018 was 4–10 TBq year−1. The 137Cs discharged to the ocean was 0.73–1.0 TBq year−1 in 2016–2018. The integrated amount of FNPP1-derived 137Cs that entered the Sea of Japan from the Pacific Ocean from 2011 until 2017 was 270 ± 20 TBq, 6.4% of the estimated amount of FNPP1-derived 137Cs in Subtropical Mode Water in the North Pacific. The integrated amount of FNPP1-derived 137Cs that returned to the North Pacific Ocean through the Tsugaru Strait from the Sea of Japan was 110 ± 10 TBq. Decontamination efforts removed 134 TBq of 137Cs from surface soil prior to February 2019, an amount that corresponded to 4% of the137Cs deposited on land in Japan

Preliminary report of "Arctic Airborne Measurement Program 2002" (AAMP02)

The Arctic Airborne Measurement Program 2002(AAMP 02) campaign was carried out in March 2002 as one of the sub programs of the project Variations of atmospheric constituents and their climate impact in the Arctic". The main goal of the project was to investigate the transport, transformation and radiative effect of trace gases and aerosols, and their role in the global climate. An instrumented jet plane, Gulfstream II(G-II), was flown from Nagoya, Japan via Barrow, Alaska to Longyearbyen(78°N , 15°E ), Svalbard, crossing the Arctic Ocean in the lower stratospher. Three local flights were made over the Greenland Sea around Svalbard and two profile flights near Barrow. The plane was equipped with CO_2 and ozone analyzers, gas and aerosol sampling systems, aerosol particle counter, nephelometer, absorption photometer, PMS particle probes, sunphotometer, dew point hygrometer and dropsonde system. During the campaign, intensitive surface operations were also conducted at Ny-Ålesund(79°N , 12°E ), Svalbard. Vertical profiles of several trace gases gave information about transport, a new observation by sunphotometer derived an aerosol optical depth in the stratosphere, and another new observation by dropsonde gave information on the polar vortex

広域観測網における硫黄同位体比を用いた越境大気汚染物質沈着量の時空間変動の評価

金沢大学環日本海域環境研究センター東アジア酸性雨モニタリングネットワークの観測網を使用し、降水中硫酸イオンの硫黄同位体比の観測をおこない、越境輸送による硫酸イオン沈着量を評価した。降水中の硫黄同位体比は、冬季に高く、夏季に低い、明瞭な季節変化を示し、その値や季節変化は、日本海側のサイトで太平洋側のサイトと比較して大きいことが明らかになった。日本海沿岸のモニタリングサイトにおける越境輸送に由来する硫酸イオンの沈着量は、太平洋沿岸域における越境輸送起源の硫酸イオン沈着量の2-3倍大きいことが明らかになった。また、アジア大陸からの越境輸送起源の硫酸イオンに、日本国内発生源由来の硫酸イオンが付加されていることが示唆された。The contribution from transboundary transport from the Asian continent to Japan at the Japanese EANET monitoring sites was evaluated from spatial and temporal distribution of anthropogenic sulfur deposition. In the coast of the Sea of Japan, temporal variations of nss-sulfur isotopic ratio　were characterized by seasonal variation with high in winter and low in summer. Similar seasonal variations were also found at the site located in the Pacific coast. The sulfur isotopic ratio was lower with smaller seasonal variation compared with those at the coastal site of the Sea of Japan. It was found that sulfate in precipitation was mainly derived from transboundary transport from the Asian continent. Transboundary transported sulfur deposition in the coastal site of the Sea of Japan (e.g. at Kajikawa, 1.1-20 mg m-2 day-1) was two-three times larger than those in the Pacific coast (e.g. at Tokyo, 0.03-6.7 mg m-2 day-1).研究課題/領域番号:26340055, 研究期間(年度):2014-04-01 - 2018-03-31出典：研究課題「広域観測網における硫黄同位体比を用いた越境大気汚染物質沈着量の時空間変動の評価」課題番号26340055（KAKEN：科学研究費助成事業データベース（国立情報学研究所）） （https://kaken.nii.ac.jp/report/KAKENHI-PROJECT-26340055/26340055seika/）を加工して作

観測と化学輸送モデルを用いた北東アジアのガス・微小粒子PAHの越境輸送の評価

金沢大学環日本海域環境研究センター2016-2018年冬季と夏季に、中国北京及び日本海沿岸に位置し、アジア大陸起源物質の越境輸送をうける能登において、ガス・微小粒子状物質を採取し、ガス・粒子態PAHの分析を行った。4環のFluとPyrはガス・粒子態、その他の4－6環PAHは粒子体で存在していた。ガス態は夏季に多く（73－97％）、冬季には粒子態での存在が大きかった。領域化学輸送輸送モデルでガス・粒子PAHの越境輸送の季節変動及び越境輸送量を評価した。Polycyclic aromatic hydrocarbons (PAHs) are one of toxic compounds in the atmospheric particles. PAHs are semivolatile organic compounds, and can therefore exist in both particle and gas-phases. Recent year, high concentrations of PM2.5 are focus on the global scale. We investigated gas-particulated phase PAHs (9 species) were observed at China, Beijing, and Japan, Noto. These were investigated by using three dimensional chemical transport model, Regional Air Quality Model for POPs version. The model performance was investigated by the comparison with the observations. As for the gas-particle partitioning, we used Junge-Pankow model (JP) as well as Loman-Lammel model (LL). In this study, we focused on semi volatile 4-rings PAHs. Results with simulation by using JP and LL model, simulated results were consistent within factor 10 against the observed one at Beijing and Noto.研究課題/領域番号:16H05624, 研究期間(年度):2016-04-01 - 2019-03-3

Latitudinal distributions of carbonyl sulfide (COS) over mid-high latitude in the Nothern Hemisphere

Concentrations of COS in the stratosphere and troposphere were determined from grab samples collected at altitudes ranging from 0.3–12 km during an aircraft flight over mid-high latitude in the Arctic Airborne Measurement Program 1998 (AAMP 98). Concentrations of COS in the troposphere were almost constant within the range of 378-433 pptv. Taking into account the lower abundance of CS2, the photochemical production of COS from CS2 oxidation was less for atmospheric COS north of 53°N. In the stratosphere below 12 km altitude, average concentrations of COS were lower than those in the troposphere. However, concentrations of COS decreased with increasing altitude 1–2 km above the tropopause. It is thought that the phototchemical oxidation of COS in the lowest part of the stratosphere was less during the observation period

Measurements of particle number mixing ratio with aircraft-borne Optical Particle Counter

Particle number mixing ratios of tropospheric and stratosphenc aerosols were observed in the Arctic Airborne Measurement Program 1998 (AAMP 98) using an Optical Particle Counter onboard a sub-sonic aircraft, the Gulfstream II (G-11) in March 1998. The observational results showed horizon­tally homogeneous distributions of particle number mixing ratio at the cruise altitude (about 12 km). On the other hand, distinct size-number distributions were found at some points on the flight paths, which suggest that effects of the warm conveyor belts appeared eastward of trough of atmospheric pressure. The characteristics of observed particle size-number distributions are discussed with isentropic backward trajectory analyses and geopotential maps

Particulate PAH Transport Associated with Adult Chronic Cough Occurrence Closely Connected with Meteorological Conditions: A Modelling Study

Exposure to polycyclic aromatic hydrocarbons (PAHs) are a cause of chronic cough occurrence in adult patients. In order to clear the relationship between transboundary transport of PAH and health effects, this study investigates the relationship between atmospheric particulate PAHs (p-PAHs), cough occurrence by epidemiological research, and meteorological conditions using a chemical transport model. Source receptor relationship (SRR) analysis revealed that a higher cough occurrence was caused by exposure to high p-PAH levels in air masses transported from central China (CCHN, 30–40° N) under westerly conditions. The p-PAHs transported from northern China (NCHN, >40° N) and the eastern part of Russia (ERUS) under north-westerly conditions also contributed to cough occurrence. The low equivalent potential temperature (ePT) and geopotential height anomaly suggested that the p-PAHs emitted near the surface were suppressed to upward transport under the colder air mass but were instead transported horizontally near the surface in the boundary layer, resulting in high p-PAH concentrations arriving in Kanazawa. Our study’s findings suggest that the air mass transport pattern associated with meteorology strongly influences the high p-PAH concentrations causing adult chronic cough occurrence