CURRENT SITUATION OF ATMOSPHERIC NANOPARTICLES IN FUKUE ISLAND, JAPAN
I. CHANDRA1,2, T. SETO1, Y. OTANI1, Y. INOMATA3, N. HAMA4, A. YOSHINO5, A. TAKAMI5,
and N. TAKEGAWA6
1
Department of Chemical and Material Engineering, Kanazawa University, Kanazawa, 920-1192, Japan.
Engineering Physics, School of Electrical Engineering, Telkom University, Bandung, 40257, Indonesia.
3
Institute of Nature and Environmental Technology, Kanazawa University, Kanazawa, 920-1192, Japan.
4
Project Planning and Development Group, Tokyo Dylec Corp., Tokyo, 160-0014, Japan.
5
Center for Regional Environmental Research, National Institute for Environmental Studies, Tsukuba,
305-8506, Japan.
6
Department of Chemistry, Tokyo Metropolitan University, Tokyo, 192-0397, Japan.
2
Keywords: New particle formation, growth, aerosol, long-range transport, East Asia.
INTRODUCTION
Various sources of air pollution, for example, from the coal-fired power plant, cement industry,
crematories, and the other anthropogenic emissions particularly in the East Asia were influenced the air
quality not only in the local area but also in the other region. These emissions such as SO2, NOx, Volatile
Organic Compounds (VOCs), and particulate matter (PM) as well as meteorological conditions have been
contributing to the more severe air pollution. Xue et al. (2016a) reported that winter season is the highest
emissions of air pollutants in Beijing, China, due to the increased indoor heating demand. They also
reported that SO2 concentration is one of primary emissions into the atmosphere. Such a trend probably
will be increased if the local government used business-as-usual scenario rather than improved pollution
control schemes (Xue et al., 2016b and 2016c). Therefore, for instance, these pollutants are transported
over a long distance by westerlies and raise serious problems in the downstream regions. They indirectly
affect the regional size distribution through a process of secondary particle formation, also known as new
particle formation (NPF). Furthermore, the fresh atmospheric aerosol was growth to several tens
nanometers by further condensation and coagulation of low volatility and semi-volatile vapors, and
heterogeneous reactions (Young et al., 2013).
We conducted field observation to investigate NPF and growth events on the ground based station in
Fukue Island, Japan over five periods (Feb. 23 to Mar. 7, 2013; Nov. 7 to 20, 2013; Nov. 2 to 24, 2014;
Feb. 27 to Mar. 17, 2015; and Feb. 27 to Mar. 25, 2016). Various instruments were carried out to this site,
such as mobility size distributions, gaseous concentrations, PM2.5 mass concentration, aerosol chemical
components, and meteorological parameters. A several NPF with onset diameters as small as 5 nm and
followed by the successive growth of particles to mobility diameters of several tens nanometers were
identified and associated with the long-range transport of polluted air masses from the East Asian region
(Chandra et al., 2016). The daily average of PM2.5 concentration was typically less than 20 µg·m-3, but
sometimes the value exceeded the target of environmental standards (≤35 µg·m-3 in daily average;
Wakamatsu et al., 2013). The concentration of SO2 during an observation campaign was 2.3±2.2 ppb,
1.3±1.1 ppb, 1.0±0.5 ppb, 1.4±1.0 ppb, and 0.8±0.5 ppb respectively. However, we only identified three
days event over the 28-days observation period in 2016 (~10%). This situation was in contrast to the
events in 2013 when we identified around 60% of event days. The level concentration of SO2 and PM2.5
might be influenced the formation rate of newly-formed nanoparticles in Fukue Island, Japan. In the
present study we measured mobility size distribution using 1nm-Scanning Mobility Particle Sizer (SMPS)
ranging from 1 to 30 nm. We analyzed how the concentration of the possible precursor (SO2) and mass
concentrations of PM2.5 of atmospheric aerosol, as well as meteorological conditions, influenced the
condition of the NPF.
METHODS
We conducted a field study to investigate NPF and growth events under the influence of air pollution
transported over large distances in the East Asia region as part of the Impacts of Aerosols in East Asia on
Plants and Human Health (ASEPH) project. We selected Fukue Island (32.8ºN, 128.7ºE), a rural island
located in the outflow region of the East-Asian plume, as a supersite for field observation. In the first
study, 2012, we collected time-resolved data on the mobility size distribution and number concentration
by a long-SMPS with a size range of 14-670 nm (Seto et al., 2013). We added a Nano-SMPS to measure
mobility size distribution between 2.5 nm and 64 nm over 2013-2015 period, and it was replaced by a
1nm-SMPS (Dp > 1 nm) in 2016. The measurements of the concentrations and chemical composition of
atmospheric aerosols and gases were available from the observation system of National Institute for
Environmental Studies (NIES) and various meteorological data were available from the observation
network for aerosol-cloud-radiation interaction (SKYNET).
RESULTS AND DISCUSSION
Figure 1 shows the daily-averaged SO2 concentration against PM2.5 mass concentration. We plotted the
data over the winter (Feb. 23 to Mar. 7, 2013; Feb. 27 to Mar. 17, 2015; and Feb. 27 to Mar. 25, 2016)
and autumn (Nov. 7 to 20, 2013; and Nov. 2 to 24, 2014) campaign. As clearly seen, SO2 and PM2.5
concentration in 2016 was slightly smaller than the level concentrations in 2013. This variation was close
to the data from Goto station (32.75ºN, 128.68ºE), which measured by Ministry of the Environment,
Japan (http://nagasaki-taiki.aa0.netvolante.jp/graph/monthly). Kurokawa et al. (2013) reported that the
emission of SO2 in China was decreased since 2007 due to local government have been controlling the
emission gas through desulphurization technologies in the large power plants. The SO2 are well-known as
one of the main precursor gas in the daytime atmospheric NPF through photochemical processes (Birmili
and Wiedensohler, 2000; Yu, 2010). Therefore, the decline of SO2 concentration might be influenced the
NPF events and growth in Fukue Island, Japan.
Figure 1. The daily-averaged SO2 concentration against the PM2.5 mass concentration.
Figure 2. Diurnal variation of atmospheric species and meteorological data on Mar. 10, 2016: (a) particle
size distributions (1 < Dp < 600 nm), (b) particle number concentration (1 < Dp < 600 nm) and SO2
concentration, (c) PM2.5 concentration and mass concentration of chemical components (Cl -, NO3-, SO42-,
Org, and NH4+), (d) meteorological data (Pressure (P), Solar radiation (I), Temperature (T), and Relative
humidity (RH)), (e) daily weather map provided by Japan Meteorological Agency and 48-h back
trajectory calculated by NOAA HYSPLIT model, and (f) vertical direction of air mass by the trajectory
analysis.
Figure 2 shows pick-up data on the time variation of atmospheric species and meteorological data
(Mar. 10, 2016). A remarkable increase in the concentration (dN/dlogDp > 104 cm-3) of nanoparticles (Dp
< 30 nm) was detected around 13:00 and continued until early evening under high concentration of the
Aitken mode particles (~100 nm). The relatively high concentration of SO2 (>1 ppb) and PM2.5 (>10
µg·m-3) were identified before the nucleation period. It suggests that the level concentration of SO2 was
sufficient to generate new particles under gradually decrease of PM2.5 mass concentration. This variation
in the SO2 and PM2.5 concentrations have a similar pattern with the fluctuation of the particle mass
concentrations measured by ACSM (PM1). The chemical species of these particulate matter (PM1) are
dominated by nitrates as well as sulfates and organics before an event period.
As shown in Fig. 2 (d), the event day was identified under cloudy day with a relatively high level of
relative humidity (>60%). It seems that some typical delay of nucleation time due to the insufficient
amount of solar radiation. Based on the NOAA HYSPLIT model (Draxler and Rolph, 2013), two air
masses origin were coming from the north and northwest of China by northwesterly wind under low
pressure (~1010 hPa) at Fukue site. It suggest that the transboundary transport of air pollutions were
observed and associated with the NPF event in the down-flow region.
CONCLUSION
Field observations to investigate the atmospheric new particle formation (NPF) and growth events
were carried out on the outflow region of the East-Asian plume in the East-China Sea (Fukue Island,
32.8ºN, 128.7ºE) over five periods (Feb. 23-Mar. 7, 2013; Nov. 7-20, 2013; Nov. 2-24, 2014; Feb. 27Mar. 17, 2015; and Feb. 27-Mar. 25, 2016). The daily-averaged SO2 concentration and PM2.5
concentration are 2.3±2.2 ppb and 17.6±8.5 µg·m-3, 1.3±1.1 ppb and 16.7±10.6 µg·m-3, 1±0.5 ppb and
14.9±6 µg·m-3, 1.4±1 ppb and 13.8±4.7 µg·m-3, and 0.8±0.5 ppb and 14.7±5.3 µg·m-3 respectively. The
scattering plot between SO2 and PM2.5 concentration tends to be decreased from year-to-year. It was
influenced the new particle formation (NPF) and growth events in 2016 campaign when we only
identified the less number of event days (~10%). Therefore, the NPF events were influenced by the
transboundary transport of polluted air under certain meteorological conditions.
ACKNOWLEDGEMENTS
This research was partly supported by KAKENHI, a Grant-in-Aid for scientific Research on Innovative
Areas “Impacts of Aerosols in East Asia on Plants and Human Health” (4003) from the Ministry of
Education, Culture, Sports, Science and Technology (MEXT), and The Environment Research and
Technology Development Fund (ERTDF) from Ministry of Environment, Japan (5-1452, 2-1403 and S12). We thank Mr. F. Li for his support of our measurements.
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