Impact of long-range transport of aerosols on the PM2.5 composition at a major metropolitan area in the northern Kyushu area of Japan

Atmospheric Environment xxx (2014) 1e10

Contents lists available at ScienceDirect

Atmospheric Environment journal homepage: www.elsevier.com/locate/atmosenv

Impact of long-range transport of aerosols on the PM2.5 composition at a major metropolitan area in the northern Kyushu area of Japan Naoki Kaneyasu a, *, Shigekazu Yamamoto b, Kei Sato c, Akinori Takami c, Masahiko Hayashi d, Keiichiro Hara d, Kazuaki Kawamoto e, Tomoaki Okuda f, Shiro Hatakeyama g a

National Institute of Advanced Industrial Science and Technology, 16-1 Onogawa, Tsukuba 305-8569, Japan Fukuoka Institute of Health and Environmental Sciences, 39 Mukaizano, Dazaifu, Fukuoka 818-0135, Japan National Institute for Environmental Studies, 16-2 Onogawa, Tsukuba 305-8506, Japan d Faculty of Science, Fukuoka University, 8-19-1 Nanakuma, Jonan-ku, Fukuoka 814-0180, Japan e Faculty of Environmental Science, Nagasaki University, 1-14 Bunkyo-machi, Nagasaki 852-8521, Japan f Faculty of Science and Technology, Keio University, 3-14-1 Hiyoshi, Kohoku-ku, Yokohama 223-8522, Japan g Tokyo University of Agriculture and Technology, 3-5-8 Saiwai-cho, Fuchu, Tokyo 183-8509, Japan b c

h i g h l i g h t s
Nss.SO2 4 were in the same level at a metropolis and an island located 190 km upwind.
Cd/Pb and Pb/Zn ratios at Fukuoka coincide with those measured at Beijing, China.
Nss.SO2 4 data at Fukuoka reflect the reported decadal SO2 emission change in China.
Long-range transport dominates PM2.5 in Fukuoka throughout the year except in summer.

a r t i c l e i n f o

a b s t r a c t

Article history: Received 30 August 2013 Received in revised form 10 January 2014 Accepted 13 January 2014

In view of the recent rapid economic growth and accompanying energy consumption in the East Asian region, particularly in China, there is much concern about the effects of emitted particulate pollutants on human health. We have thus investigated the impact of long-range transport of aerosols on urban air quality in the upwind areas of Japan by comparing the PM2.5 composition collected for multiple years in Fukuoka, a representative metropolis in the Kyushu area, and in Fukue Island, located 190 km southwest of Fukuoka. Daily averaged PM2.5 concentrations in Fukuoka and Fukue were almost identical. PM2.5 concentrations at these sites were dominated by sulfate and particulate organics, and their fluctuation patterns were similar except for organics in the warm season. In contrast, those of nitrate and elemental carbon differed substantially between the sites. In addition, the ratios of Pb/Zn and Cd/Pb in Fukuoka were close to the reported values in Beijing. Non-sea-salt sulfate concentration in Fukuoka measured in this study and reported in the past measurements apparently coincided with the decadal SO2 emission change in China reported in a recent emission inventory. Therefore, we conclude that even in a city as large as Fukuoka, the PM2.5 concentration in the northern part of the Kyushu area is primarily dominated by the inflow of long-range transported aerosols throughout the year, except in the summer, rather than local air pollution emitted at each site. Ó 2014 Elsevier Ltd. All rights reserved.

Keywords: PM2.5 Long-range transport East Asia Sulfate Metallic element NAAQS

1. Introduction * Corresponding author. Tel.: þ81 29 861 8365; fax: þ81 29 861 8358. E-mail addresses: [email protected] (N. Kaneyasu), yamamoto@fihes.pref. fukuoka.jp (S. Yamamoto), [email protected] (K. Sato), [email protected] (A. Takami), [email protected] (M. Hayashi), [email protected] (K. Hara), [email protected] (K. Kawamoto), [email protected] (T. Okuda), [email protected] (S. Hatakeyama).

In the middle of January 2013, an extremely high concentration of PM2.5 exceeding 800 mg m3 (hourly data) was observed at the U.S. Embassy in Beijing, China. This raised concerns about the acute health effects of air pollution on the local residents. Severe air pollution in mega cities of China (e.g., Chan and Yao, 2008) has

1352-2310/$ e see front matter Ó 2014 Elsevier Ltd. All rights reserved. http://dx.doi.org/10.1016/j.atmosenv.2014.01.029

Please cite this article in press as: Kaneyasu, N., et al., Impact of long-range transport of aerosols on the PM2.5 composition at a major metropolitan area in the northern Kyushu area of Japan, Atmospheric Environment (2014), http://dx.doi.org/10.1016/j.atmosenv.2014.01.029

2

N. Kaneyasu et al. / Atmospheric Environment xxx (2014) 1e10

Fig. 1. Locations of aerosol monitoring and sampling sites in Fukuoka, Fukue Island, and Nagasaki. Related sites referred in this study are indicated in italic letters.

become a sociopolitical issue, and such pollution has been studied to determine its adverse health effects (e.g., Li et al., 2013; Shang et al., 2013). In addition, increasing emissions of aerosols and the precursors of photochemical O3 from the East Asian region have become a focus of research in view of short-lived climate forcers. Long-range transport of aerosols, presumably from mainland China, has been studied in various locations in neighboring countries in East Asia. For example, long-term monitoring studies on islands such as Oki Island, Japan (Mukai et al., 1990), and Jeju Island, Korea (e.g., Chen et al., 1997; Park et al., 2004), have characterized the aerosols transported from the Asian continent. Samplings of lake sediment core have revealed the historical record of transported metallic elements that are potentially hazardous to human health or may affect aquatic environments (Kusunoki et al., 2012). At Cape Hedo of Okinawa Island, Japan, the detailed size distribution of major aerosol components and the highly time-resolved characteristics of transported aerosols were analyzed using an aerosol mass spectrometer (Takami et al., 2007). These studies have focused mainly on the nature of long-range transport phenomena, or the chemical/microphysical aging procedure of transported pollutants. However, the effect of long-range transported pollutants on air pollution status or the achievement of the National Ambient Air Quality Standard (NAAQS) in each country has rarely been analyzed except for the trans-Pacific transport of ozone on the air quality of the U.S. west coast (e.g., Cooper et al., 2011; Huang et al., 2010; Parrish et al., 2010). In the countries of East Asia where the continental outflow of air pollutants is observed, the current interest revolves around the question of whether the long-range transport of aerosols is merely an episodic event or a constant supplier of pollutants that substantially affects the achievement of the NAAQS. To address this problem, we have analyzed the impact of longrange transported aerosols on the PM2.5 concentration in Fukuoka, a representative metropolis in the northern Kyushu area, Japan. The prevailing westerlies first hit the Japanese main islands at Fukuoka, and this region is less influenced by emissions from other parts of Japan. Therefore, the location is preferable for

detecting the constant effect of long-range transported aerosols on the state of air quality in an urban area. Major aerosol components in PM2.5 collected in Fukuoka are compared with those collected 190 km upwind of the westerlies at Fukue Island. We further infer the potential emission source area of PM2.5 in Fukuoka by the ratio of metallic elements as an emission source fingerprint. Another current issue regarding pollutant emission in the East Asian region is the decadal emission change in China. The emission of air pollutants in the East Asian region increased during the 1990s and the early 2000s (e.g., Ohara et al., 2007). However, a recent emission inventory study pointed out that SO2 emission in China peaked in 2006 and started to decrease gradually after that (Lu et al., 2010). Some remote sensing data have confirmed the recent decreasing trend of SO2 (Li et al., 2010) and aerosol optical depth (Itahashi et al., 2012). If this is the case, the in situ aerosol data measured at the lee side of mainland China may have reflected the suggested change in SO2 emission. To acquire insight into this, we compared the present data to those obtained in the 1990s and the 2000s. 2. Sampling locations and measurements The locations of Fukue Island and Fukuoka are indicated in Fig. 1. Fukuoka is the largest center of commerce in the Kyushu region of Japan, with a population of 2,400,000 in the greater Fukuoka metropolitan area. Nagasaki is a middle-sized city with a population of 300,000; shipbuilding is the major industry. Fukue Island, with an area of 326 km2 and a population of 37,000, is located 190 km southwest of Fukuoka; the major industries are agriculture and fishery, and the anthropogenic emissions are insignificant. Aerosol sampling was conducted from March 2010 to March 2013 at Fukuoka-Dazaifu and from March 2010 to February 2013 in Fukue Island. In Fukue Island, a low-volume PM2.5 air sampler equipped with a PM10 inlet followed by a WINS particle size separator (Partisol-Plus Model-2025, Rupprecht & Patashnick) was operated with a time resolution of one week. Quartz-fiber filters (Pallflex 2500 QAT-UP, 47 mm in diameter) were used for aerosol

Please cite this article in press as: Kaneyasu, N., et al., Impact of long-range transport of aerosols on the PM2.5 composition at a major metropolitan area in the northern Kyushu area of Japan, Atmospheric Environment (2014), http://dx.doi.org/10.1016/j.atmosenv.2014.01.029

3. Results and discussion 3.1. PM2.5 mass concentrations in Fukue Island, Fukuoka, and Nagasaki The time series of the daily averaged mass concentration of PM2.5 in Fukue Island, Fukuoka, and Nagasaki measured by TEOM are shown in Fig. 2 for the period from March 2010 to August 2011. The concentrations and the fluctuation patterns in these sites were close to each other throughout the year, although the concentrations in Fukuoka were slightly higher than those in Fukue Island and Nagasaki in the warm season (i.e., from May to September). In some high concentration events, PM2.5 concentrations in Fukue Island were higher than those in Fukuoka and Nagasaki (e.g., from the end of March to the first week of April 2010, and the first week of February 2011). After July 2011, PM2.5 concentrations in Fukuoka were monitored at Fukuoka University and Dazaifu concurrently. Regardless of the distance of 13 km, the concentrations at the sites were almost identical except in the cold season (see Appendix B). The distances between Fukuoka and Nagasaki and between Nagasaki and Fukue Island are both approximately 100 km, and these sites are located within completely different air basins. The similarity of concentrations and temporal variations appears to suggest that the PM2.5 concentrations at these three sites are dominated by regional pollution instead of independent local emissions in each area.

-3

3

80

(a)

PM2.5 (TEOM) Fukue Island Fukuoka Nagasaki

60 40 20 0

Mar.

Apr.

May

Jun.

Jul.

Aug.

-3

Daily mean concentration ( µg m )

2010 80

(b)

PM2.5 (TEOM)

60

Fukue Island Fukuoka Nagasaki

40 20 0

Sep.

Oct.

Nov.

Dec.

Jan.

2010 -3

Daily mean concentration ( µg m )

collection at a flow rate of 16.67 L min1. However, due to mechanical problems with the PM2.5 sampler (i.e., wetting of the filter by rainwater) in Fukue Island, reliable aerosol samples were collected after September 2010. In Fukuoka, to determine the metallic elements in addition to the major components in PM2.5, aerosol collection was conducted with a time resolution of 24 h using a high-volume air sampler (HV-1000F, Shibata) with an impactor-type particle separator HVI2.5 (Kaneyasu, 2010) attached (Appendix A). The HVI2.5 was operated at a flow rate of 740 L min1, and it collected PM2.5 aerosol onto quartz-fiber filters (Pallflex 2500 QAT-UP, 20  25 cm) placed behind the impaction plate. Aerosol loaded filters were sealed in plastic bags and stored in refrigerators (<18  C) before analysis. Water-soluble components were extracted with distilled and deionized water from a section of filters. Ions in extract were analyzed using ion chromatography (Dionex IC2000). Thermal-optical transmission analysis (Sunset Lab, Model-4) with the IMPROVE protocol was adopted for the determination of organic and elemental carbon content in the particles. One-fourth of the filter containing Fukuoka aerosols was dissolved into HFeHNO3eH2O2 solution heated in a microwave, and metallic elements (Al, Cd, Fe, Mn, Ni, Pb, V, and Zn) were determined using inductively-coupled plasma mass spectrometry (Thermo Fisher Scientific iCAP6200). The detection limit of these elements was 49, 0.0072, 13, 0.21, 0.51, 0.30, 0.053, and 2.2 ng m3, respectively, which was defined as twice the standard deviation of determined values in blank filters. Hourly mass concentrations of PM2.5 were monitored continuously in Fukuoka, Fukue Island, and Nagasaki using tapered element oscillating microbalances (TEOM-1400a, Rupprecht & Patashnick). At the Fukue Island site, the inlet tube of TEOM had two 90 bending parts (r ¼ 40 cm) between the PM10 inlet and the PM2.5 WINS impactor due to space limitations in the monitoring station. In Fukuoka, TEOM was operated at Fukuoka University, located 13 km away from the Fukuoka-Dazaifu aerosol sampling site. After July 2011, the PM2.5 concentration was also monitored concurrently at Fukuoka-Dazaifu using the b-ray absorption method (PM-712, Kimoto Electric).

Daily mean concentration ( µg m )

N. Kaneyasu et al. / Atmospheric Environment xxx (2014) 1e10

Feb.

2011

80

(c)

PM2.5 (TEOM) Fukue Island Fukuoka Nagasaki

60 40 20 0

Mar.

Apr.

May

Jun.

Jul.

Aug.

2011 Fig. 2. Time series of daily averaged PM2.5 concentrations in Fukue Island, Fukuoka (Fukuoka University before June 2011, Dazaifu after July 2011), and Nagasaki (a) from March to August 2010, (b) from September 2010 to February 2011, (c) from March 2011 to August 2011.

3.2. An example of a short-term high concentration event in the spring In Fukue Island, daily PM2.5 aerosol samples were collected as part of an intensive measurement campaign conducted synchronously with the airborne measurement in the East China Sea (Hatakeyama et al., in this issue). Major components that comprise the mass concentration of accumulation mode aerosols are known  þ to be a limited number of chemical species such as SO2 4 , NO3 , NH4 , and some materials expressed by generic terms such as elemental carbon (EC) and particulate organic carbon (OC). In this paper, EC and OC are expressed as TOT-EC and TOT-OC, respectively, to indicate the adopted analytical method explicitly. Fig. 3a and b show an example of daily variations of major PM2.5 components in Fukue Island and Fukuoka in March 2012. In the figures, two prominent transport events, peaked on March 7 and 15, are identified. On March 10, a sharp increase in concentration was observed in Fukue Island, while that in Fukuoka is not recognizable in figure (see Appendix C).

Please cite this article in press as: Kaneyasu, N., et al., Impact of long-range transport of aerosols on the PM2.5 composition at a major metropolitan area in the northern Kyushu area of Japan, Atmospheric Environment (2014), http://dx.doi.org/10.1016/j.atmosenv.2014.01.029

4

N. Kaneyasu et al. / Atmospheric Environment xxx (2014) 1e10

Concentration ( µg m-3)

50

-

(a)

Fukue Island

Cl

NH4+

40

-

NO3

Year

2-

SO4 TOT-OC

30

2011 2012

TOT-EC

20

Fukue Is.

Fukuoka (Dazaifu)

NO 3

nss.SO2 4

TOT-EC

TOT-OC

NO 3

nss.SO2 4

TOT-EC

TOT-OC

0.17 0.07

6.0 5.7

0.40 0.24

1.6 1.4

1.4 1.3

4.6 5.2

0.95 1.0

2.2 2.7

unit: mg m3.

10 0

7

8

9 10 11 12 13 14 15 16 17 18

Day in March, 2012 50 Concentration ( µg m-3)

Table 1 Annual averaged concentrations of PM2.5 compositions in Fukue Island and Fukuoka (Dazaifu), 2011e2012.

(b)

Fukuoka

-

Cl

+

NH4

40

NO3-

30

SO42TOT-OC

20

TOT-EC

10 0

7

8

9 10 11 12 13 14 15 16 17 18

Day in March, 2012 Fig. 3. Daily concentrations of major components in PM2.5 collected from March 7 to 18, 2012, at (a) Fukue Island and (b) Fukuoka.

The dominant component at both sites was SO2 4 , which exceeded 20 mg m3 in Fukue Island on March 7, 8, and 15, and 17 mg m3 in Fukuoka on March 7 and 8. The synchronized shortterm variation of nss.SO2 4 in Fukue Island and Fukuoka was also reported by Shimohara et al. (2001). The second largest contributor of PM25 in Fukue Island was OC, while those in Fukuoka were NO 3 and OC. The sum of components in Fig. 3 sometimes exceeded 35 mg m3, which is the regulated value of NAAQS in Japan for a 24h average concentration of PM2.5. Note that OC was not converted to the mass of particulate organic matter, and sodium and soil dust components were not included in Fig. 3. The details of the aerosol characteristics measured aloft, the meteorological conditions, and the calculated transport pathways during this event are discussed in Hatakeyama et al. (in this issue). 3.3. Comparison of major PM2.5 components in Fukue Island and Fukuoka on a weekly basis To reveal which components of PM2.5 contributed the yearround temporal variations of PM2.5 mass concentrations in Fig. 2, we compared the concentrations of TOT-EC, TOT-OC, nss.SO2 4 , and NO 3 in Fukue Island and Fukuoka by weekly averaged bases. To compare the one-week data in Fukue Island, 24-h data in Fukuoka were averaged for one week, which corresponded to the sampling time in Fukue Island. The annually averaged concentrations of these major compositions are listed in Table 1. Concentrations of TOT-EC in Fukuoka (Fig. 4a) were systematically higher than those in Fukue Island throughout the year. Summer (i.e., June to September) minima in the seasonal variation are recognizable at both sites. This summer low, i.e., fall-winter-spring high, tendency in the seasonal variation was commonly identified in other major components. EC had been one of the important

contributors of particulate air pollutants in Japan before the 2000s. After the introduction of “Long-term Regulation” in 1998 and “New Short-term Regulation” in 2003 for the exhaust of diesel-powered vehicles, the EC concentration in urban areas in Japan decreased significantly. Accordingly, the annual average concentration of TOTEC in Fukuoka was approximately 1 mg m3 in 2011 and 2012 (Table 1). Nevertheless, the EC concentration during winter to spring in Fukue Island comprised 1/3 to 1/2 of that in Fukuoka.  The time series of non-sea-salt (nss.) SO2 4 , TOT-OC, and NO3 at two sites showed features that were different from that of TOT-EC. The concentrations of nss.SO2 4 were almost identical at the two sites, and that of Fukue Island was sometimes slightly higher than that in Fukuoka (Fig. 4b). In the time series of TOT-OC (Fig. 4c), the concentration in Fukuoka was similar to or slightly higher than that in Fukue Island in most seasons, although the concentration difference increased in the warm season, i.e., during April to October. In particular, the difference was pronounced in the warm season in 2012, when the TOT-OC concentration in Fukuoka became more than twice that in Fukue Island. The concentration of NO 3 in Fukuoka was exceedingly higher than that in Fukue Island (Fig. 4d), exhibiting a pronounced seasonal variation with a winter to spring maximum and a summer minimum. With these variations, some insights into the PM2.5 composition in Fukuoka are deduced. The most distinct feature is the fact that nss.SO2 4 , the largest contributor of PM2.5 in Fukuoka, is dominated by the inflow of long-range transport but not by local emissions. If the pollution was mainly transported from mainland Kyushu to Fukue Island, the decrease in the concentration of nss.SO2 4 due to the dispersion and dilution effect would be expected. In that case, the dilution factor should be from 3 to 15, as estimated from the EC concentration ratio at the two sites, because EC is a primary particle emitted from combustion processes. To compensate for this dilution, the oxidative formation from SO2 to produce a sulfate concentration that is 3e15 times greater than that at the starting point (i.e., Fukuoka) is necessary. This is unlikely in the course of the transport of about a 200 km distance. Most of the nss.SO2 4 appears to be in the form of ammonium salt. In Fukuoka, daily concentraþ tions of nss.SO2 4 and NH4 are highly correlated (r ¼ 0.89), and many of the plots are scattered on or above the molar ratio line that forms (NH4)2SO4 (Fig. 5). Likewise, the concentration of OC in Fukuoka appears to be controlled by long-range transported aerosols in general, while the buildup of concentration in the warm season can be explained by local emissions. Photochemical formation of secondary organic aerosols in relatively calm air during the warm season is the probable supplier of OC in Fukuoka. On the contrary, nitrate (NO 3 ) and EC in Fukuoka are considered to be sourced mostly from locally emitted urban air pollutants rather than those of long-range transported ones. The pronounced seasonal variation of NO 3 that peaked in winter apparently reflects the dissociation characteristics of NH4NO3 that correspond to the change in ambient temperature rather than the transported amount. An exception is the episode in February 1e8, 2011, marked with T in Fig. 4d, when high concentrations of NO 3 were measured

Please cite this article in press as: Kaneyasu, N., et al., Impact of long-range transport of aerosols on the PM2.5 composition at a major metropolitan area in the northern Kyushu area of Japan, Atmospheric Environment (2014), http://dx.doi.org/10.1016/j.atmosenv.2014.01.029

N. Kaneyasu et al. / Atmospheric Environment xxx (2014) 1e10

20

(a)

4 3

T

2 1 Sep. Dec.

Mar.

Jun.

2010

-3

Dec.

Mar.

2011

Jun.

Sep. Dec.

Fukuoka nss.SO42-

15 10 5 0

Mar.

Sep. Dec.

2012

Fukue TOT-OC

T

5

Fukuoka TOT-OC

4 3 2 1 Sep. Dec.

Mar.

Jun.

2010

Sep.

Dec.

Mar.

2011

Jun.

Sep. Dec.

Jun.

Sep.

Dec.

Mar.

2012

Mar.

2011

Jun.

Sep. Dec.

Mar.

2012

(d)

Fukue NO3-

15

Fukuoka NO3T

10 5 0

0

Mar.

2010

20

(c)

Fukue Is. nss.SO42-

T

-3

6

Sep.

(b)

-3

Fukuoka TOT-EC

0

Concentration ( µg m )

Concentration ( µg m )

Fukue TOT-EC

5

Concentration ( µg m )

-3

Concentration ( µg m )

6

5

Sep. Dec.

2010

Mar.

Jun.

Sep.

2011

Dec.

Mar.

Jun.

Sep. Dec.

Mar.

2012

 Fig. 4. Time series of weekly average concentrations of (a) TOT-EC, (b) non-sea-salt SO2 4 , (c) TOT-OC, and (d) NO3 in PM2.5 collected in Fukue Island and Fukuoka from September 2010 to February 2013. Mark T indicates the transport event in February 1e8, 2011.

NH4+ concentration (µmol m-3)

1.0

Fukuoka 0.8

0.6

0.4

0.2

r = 0.89 (n = 911) 0.0

0

0.1

0.2

0.3

0.4

0.5

92.2% of the PM2.5 in Fukue Island originated from areas outside of Japan, which agrees with our observational analyses. Synoptic scale meteorology primarily controls the accumulation of air pollutants on the Asian continent and their intermittent outflow to the East China Sea (e.g., Kaneyasu et al., 2000). In the winter of 2012e2013, the increase of nss.SO2 4 , EC, and OC in Fukue Island was not obvious compared to that in the preceding two years. If any anomalous synoptic scale meteorological conditions in this winter affected this phenomenon, it was possible that the same meteorological condition also affected the occurrence of extremely severe air pollution in the northern part of China observed in January 2013.

nss.SO42- concentration (µmol m-3) 2 Fig. 5. Scatter plots of NHþ in PM2.5 collected in Fukuoka from 4 versus nss.SO4 September 2010 to February 2013. Filled triangles indicate the data corresponding to 2 the event T in Fig. 4. Broken line indicates the molar ratio of NHþ 4 and SO4 that forms (NH4)2 SO4.

in Fukue Island and Fukuoka concurrently. In this event, TOT-OC concentrations were also high (Fig. 4c). From the above, we concluded that PM2.5, in particular sulfate and particulate organics, in the northern Kyushu area of Japan was largely dominated by long-range transported aerosols throughout most of the year. In addition to this regional pollution, locally formed particulate organics in summer and ammonium nitrate in winter appeared to be contributing to the PM2.5 concentration in Fukuoka to a certain extent. Recently, Ikeda et al. (2013) has estimated the source area contribution of PM2.5 measured in Fukue Island for the year 2010. Their numerical analysis showed that

3.4. Ratios of metallic elements in Fukuoka Metallic elements comprise a minor fraction of the PM2.5 mass concentration. However, as primary particles, they are expected to conserve the characteristics of the emission sources as a fingerprint. With the following discussion on the ratios of metallic elements, it is further suggested that PM2.5 aerosols collected in Fukuoka were largely affected by the emission from China. The time series of Pb and Fe concentrations in Fukuoka (Fig. 6) typically demonstrate the difference in fluctuation patterns of natural and pollution-derived aerosols. Al (not shown in the figure) and Fe showed three extreme maxima (exceeding 3000 ng m3) that apparently correspond to the occurrence of Asian Dust events. In contrast, Pb showed frequent increases except in summer, probably corresponding to the transport events of air pollution by continental outflow. These outflows are normally induced by the passage of cold fronts of cyclones or the northwest flow around

Please cite this article in press as: Kaneyasu, N., et al., Impact of long-range transport of aerosols on the PM2.5 composition at a major metropolitan area in the northern Kyushu area of Japan, Atmospheric Environment (2014), http://dx.doi.org/10.1016/j.atmosenv.2014.01.029

6

N. Kaneyasu et al. / Atmospheric Environment xxx (2014) 1e10

6000

Fukuoka

Fe concentration (ng m-3)

Pb concentration (ng m-3)

150

Pb Fe

100

4000

50

2000

0 Mar.

Jun.

Sep.

Dec.

Mar.

Jun.

2010

Sep.

Dec.

2011

0

2012

Fig. 6. Time series of daily concentrations of Pb (left axis) and Fe (right axis) collected in Fukuoka from March 2010 to March 2012.

migrating anticyclones that emerge on the East China Sea (Kaneyasu et al., 2000). Concentrations of some metallic elements had a high correlation with each other. In particular, concentrations of Pb and Cd had the highest correlation coefficient, r ¼ 0.88 (n ¼ 746), followed by Zn and Pb with r ¼ 0.84 (n ¼ 746), as indicated in Fig. 7. The average Pb/ Zn ratio in Fukuoka of 0.44 (the slope of linear regression line in Fig. 7a) is significantly higher than that measured from total suspended particulates (TSP) in Tokyo, Japan (0.29, 2010 annual average) and close to the value measured from TSP in Beijing (0.43, 2008e2009 average) (Okuda et al., 2013). At Xinglong, 100 km northeast of Beijing, the average Zn/Pb ratio was calculated to be 0.41 in fine aerosol (Da < 2.1 mm) collected in September, 2008, from the data of Pan et al. (2013). In the past, the ratio of Pb/Zn was higher than the present value at the remote islands in Japan, such as Oki, Amami-oshima, and

100

Fukuoka

Pb concentration (ng m -3)

(a)

3.5. Comparison of nss.SO2 4 with past measurements 50

Slope = 0.44 r = 0.84 0

0

50

100

150

200

Zn concentration (ng m -3) 2.0

Fukuoka

(b) Cd concentration (ng m -3)

Miyako Island. The ratio of Pb/Zn was approximately 1 in the 1980s (Mukai et al., 1990) and the early 1990s (Kaneyasu and Takada, 2004). The ratio has decreased after the use of leaded gasoline ended in Korea in 1994 and was officially banned in China in 2000. For example, Hsu et al. (2005) reported the Pb/Zn ratios in PM2.5 collected from 2002 to 2003 in Taipei, Taiwan, for “Asian Dust” and “northeast monsoon” periods as 0.55 and 0.50, respectively, which were similar to, or slightly higher than, the present data from Beijing and Fukuoka. Regarding the ratio of Cd/Pb, the slope of regression line (¼0.020) in Fukuoka (Fig. 7b) is close to that measured for PM2.5 during the extremely high concentration episode in Beijing in the middle of January, 2013 (Yonemochi et al., 2013); the average ratio of Cd/Pb on January 9e23, 2013, was 0.017. The ratio in Beijing TSP during the period of 2001e2006 was calculated to be 0.016 in average from the data of Okuda et al. (2008), and that at Xinglong in fine aerosol (Da < 2.1 mm) was 0.022 from the data of Pan et al. (2013). In Taipei, the ratios of Cd/Pb were 0.017 and 0.024 for “Asian Dust” and the “northeast monsoon” period, respectively, during the period of 2002e2003 (Hsu et al., 2005). It is of interest that these measured ratios have not changed greatly since 2001, at least from these data. Okuda et al. (2008) reported that the annual rates of change in Cd and Pb concentrations in Beijing were close to each other, i.e., 19.0% and 19.8%, respectively. This implies that Cd and Pb observed in Beijing have a common emission source, and the emission intensities increased significantly during the early 2000s. In contrast, the correlation of Pb and Cd at Oki Island in the 1980s was not necessarily high (i.e., in the range from 0.3 to 0.6) (Mukai et al., 1990). This is probably due to the relatively large contribution of Pb emitted from leaded gasoline used in Korea and China in the 1980s. In Hyogo prefecture, a neighboring area west of Osaka, Japan, metallic elements in the suspended particulate matter (SPM), which is defined by the mass concentration of particles with aerodynamic diameters less than 10 mm (100% cutoff), have been measured monthly since 1975 (Hyogo Prefecture, 2011). The average Cd/Pb ratio between the Japanese fiscal years (Aprile March) 2008 and 2011 at nine sites in Hyogo prefecture was 0.045, which is significantly higher than that in Fukuoka.

1.5

1.0

0.5

Slope = 0.020 r = 0.88 0.0

0

20

40

60

80

100

Pb concentration (ng m -3) Fig. 7. Scatter plots of (a) Pb versus Zn and (b) Cd versus Pb concentrations in PM2.5 collected in Fukuoka from March 2010 to March 2012.

Regarding the question of whether a change in the emission of aerosols or precursory gases in China can be detected at the lee locations as a long-range transport, we compared the present data with nss.SO2 4 concentrations measured in the past, since they have been relatively well documented since the 1990s. In Fukuoka, the annual average concentration of nss.SO2 4 in TSP between the Japanese fiscal years 1998 and 2007 was reported by Oishi et al. (2009). For comparison, our daily data are averaged for the Japanese fiscal years 2010, 2011, and 2012 (Fig. 8). In the figure, an increasing trend is recognizable until 2007; but after 2010, the concentration decreased to the level it was in 2003. This is in agreement with the MODIS/Terra aerosol optical depth (AOD) data by Itahashi et al. (2012), which indicated that the annual mean AOD of fine aerosols over the Sea of Japan in 2010 decreased to that of the 2002e2004 level. Although there are two years of blank data, the nss.SO2 4 concentration in Fukuoka apparently coincides with the suggested SO2 emission change in China that peaked in the late 2000s and started to decrease after that. We next compare the data from the islands in the northern part of the East China Sea (Fig. 9). Hayami (2005) measured fine (Da < 2 mm) aerosol components in Fukue Island in the spring (MarcheApril) of 2000, 2001, and 2002. These data are not largely different from MarcheApril average concentrations in the present

Please cite this article in press as: Kaneyasu, N., et al., Impact of long-range transport of aerosols on the PM2.5 composition at a major metropolitan area in the northern Kyushu area of Japan, Atmospheric Environment (2014), http://dx.doi.org/10.1016/j.atmosenv.2014.01.029

N. Kaneyasu et al. / Atmospheric Environment xxx (2014) 1e10

This study 5.0

5.0

4.8

5.8

5.3

6.2

6.1

5.3

4

5.4

6

7.4

Oishi et al. (2009)

7.4

8

8.7

nss.SO42- in Fukuoka

5.2

Concentration ( µg m-3)

10

2 0

1998 1999 2000 2001 2002 2003 2004 2005 2006 2007 2008 2009 2010 2011 2012

Japanese fiscal year (April - March) Fig. 8. Annual averaged concentrations of nss.SO2 4 in Fukuoka in the present study and data from Oishi et al. (2009). Note that data of Oishi et al. (2009) were measured from TSP. Numbers in the bars indicate concentrations.

study. Mori et al. (1997) reported the one-month averaged concentration in TSP at Tsushima Island, Japan collected in April 1990. The value 4.7 mg m3 is comparable to those of the MarcheApril average in Fukue Island in 2000 and 2010. When our annual average data from Fukue Island in 2011 and 2012 are compared with those measured at Gosan station, Jeju Island, Korea in the 1992e1995 average (Chen et al., 1997) and the 1992e2002 average (Park et al., 2004), the Fukue data are apparently smaller than those from Jeju Island. From these geographically sparse and intermittent measurements on the islands, it is difficult to recognize the trend in concentration. 4. Conclusions

2 0

1990

'1992-1995'1992-2002'

2000 2001 2002

'

5.2

7.5

4.6

4.1

5.4

6.7

6.9 4.9

6.7 Jeju (Park et al., 2004)

4

Fukue, Mar.-Apr. Fukue (This study) (Hayami, 2005) 6.8 Jeju (Chen et al., 1997)

6

4.7 Tsushima (Mori et al., 1997)

Concentration ( µg m-3)

nss.SO42- on the islands in the East China Sea

10 8

coincided with the measured nss.SO2 4 concentrations in Fukuoka, while the long-term trend was not clearly seen from the intermittent data on the islands in the northern part of the East China Sea. We conclude, therefore, that even in a city as large as Fukuoka, the PM2.5 concentration is primarily dominated by regional, i.e., long-range transported, air pollution rather than domestic urban air pollution throughout the year, except in the summer. In Japan, the NAAQS for particulate air pollution has been regulated in terms of SPM since 1972. However, the establishment of the NAAQS for PM2.5 was late and has come into force since September 2009. Therefore, the deployment of automated PM2.5 monitors has just started, and it is still limited to urban areas. The results of our study imply that the achievement of the PM2.5 NAAQS (annual mean: 15 mg m3, daily mean: 35 mg m3) will not be an easy task, at least in the northern Kyushu area. To improve the air quality in this area, internationally collaborative efforts to reduce the emission of pollutants, either by means of political or technological ways, have become critically essential. Acknowledgments The authors appreciate the support of Dr. S. Hasegawa and Dr. S. Yonemochi (Center for Environmental Science in Saitama) in the weighing of aerosol filters. This research was supported by a Grantin-Aid for Scientific Research on Innovative Areas “Impacts of Aerosols in East Asia on Plants and Human Health” (Grant No. 20120007) funded by the Ministry of Education, Culture, Sport Science and Technology (MEXT), Japan. Appendix A. Field test of a high-volume impactor HVI2.5

The parallel sampling of PM2.5 aerosol in Fukuoka and Fukue Islands revealed that nss.SO2 4 , which is the largest contributor of PM2.5 in Fukuoka, is dominated by the inflow of long-range transport but not by local emissions. TOT-OC, the second contributor of PM2.5 mass, is also controlled by the inflow of pollutants, although it is partly affected by local air pollution in Fukuoka during the warm season. The ratios of Cd/Pb and Pb/Zn in PM2.5 in Fukuoka were compared with those measured in mega-cities in East Asia, such as Beijing, Tokyo, and Taipei. The ratios in Fukuoka were close to the aerosol composition in Beijing. The decadal change in the SO2 emission in China reported in the recent emission inventory study

12

7

2010 2011 2012

Year Fig. 9. Concentrations of nss.SO2 4 on the islands in the northern part of the East China Sea. Note that filled bars indicate the annually averaged data, and diagonally hatched bars indicate springtime data (Tsushima Island: April, Fukue Island: MarcheApril). Numbers on the bars indicate concentrations.

HVI2.5 is a multiple nozzle type impactor attachable to conventional high volume air samplers. The schematic drawing of HVI2.5 and a photograph attached to a high-volume air sampler are shown in Figs. A1 and A2, respectively. The description of the development of this device and the size separation curves applied for ambient aerosol are found in Kaneyasu (2010). Parallel operation of a high-volume air sampler (HVe1000F, Sibata) attached with HVI2.5 and low-volume PM2.5 samplers (Partisol FRM-2000, Rupprecht & Patashnick) designated as “reference methods” (40 CFR Part 53) was conducted at Fukuoka-Dazaifu in the fall of 2010. The high-volume air sampler collected the aerosols onto 20  25 cm quartz-fiber filters at a flow rate of 740 L min1, while for low-volume PM2.5 samplers, 47-mm-diameter polytetrafluorethylene (PTFE) filters with an integral polypropylene support ring (PM2.5 Air Monitoring Membrane, Whatman) were used. On the impaction plate of HVI2.5, a glass fiber filter impregnated with lowvolatile silicone oil (Dow Corning Toray SH704) was placed to lower the bounce and re-suspension of particles. Filters were conditioned in 20  C and 50% relative humidity for 24 h and weighed by an analytical microbalance before and after the aerosol sampling. Due to the limited availability of research facilities, the conditioning relative humidity used here was higher than the designated relative humidity of 30e40% in Appendix L to Part 50 of CFR 40e50 (U.S. EPA). Fig. A3 shows a comparison of the parallel sampling results of PM2.5 mass concentrations by Partisol FRM-2000 and the HVI2.5 attached high-volume air sampler. The measured mass concentrations of aerosols agreed reasonably well in the range at least below 45 mg m3. The effect of re-suspension or bounce of particles from the impaction substrate should be significant when a high concentration of giant particles occurs, such as during Asian Dust events, due to the flat design of the impaction plate without a barb.

Please cite this article in press as: Kaneyasu, N., et al., Impact of long-range transport of aerosols on the PM2.5 composition at a major metropolitan area in the northern Kyushu area of Japan, Atmospheric Environment (2014), http://dx.doi.org/10.1016/j.atmosenv.2014.01.029

8

N. Kaneyasu et al. / Atmospheric Environment xxx (2014) 1e10

Fig. A1. Schematic drawing of HVI2.5 (unit: mm).

Please cite this article in press as: Kaneyasu, N., et al., Impact of long-range transport of aerosols on the PM2.5 composition at a major metropolitan area in the northern Kyushu area of Japan, Atmospheric Environment (2014), http://dx.doi.org/10.1016/j.atmosenv.2014.01.029

N. Kaneyasu et al. / Atmospheric Environment xxx (2014) 1e10

9

timing of the filter change in Fukuoka (0900 local time) and the arrival of narrow-banded air pollution on March 10 (Fig. S1). In Fukuoka, a high concentration period of PM2.5 aerosols was divided into the filter samples of March 10 and 11. In Fukue Island, it was mainly included in the March 10 filter sample because the arrival of the pollution band was earlier and the filter exchange time was later (1200 local time) than that of Fukuoka. Appendix E. Supplementary data Supplementary data related to this article can be found at http:// dx.doi.org/10.1016/j.atmosenv.2014.01.029. References

HVI2.5 attached high-vol sampler ( µg m-3)

Fig. A2. A photograph of HVI2.5 attached to a high-volume air sampler.

50

Parallel operation test at Fukuoka

40

(Oct.25 - Nov.10, 2010)

30 20 Slope = 0.99 Intersept = 0.34 r = 0.99

10 0

0

10

20

30

40

50

-3

Partisol FRM-2000 ( µg m ) Fig. A3. Comparison of aerosol mass concentrations collected by an FRM-type PM2.5 low-volume air sampler (Partisol-2000) and an HVI2.5 attached high-volume air sampler operated at a flow rate of 740 L m3. Aerosol samples were collected in Fukuoka from October 25 to November 10, 2010.

Appendix B. Difference of PM2.5 data measured at two sites in Fukuoka In winter (December) to spring (April) months, PM2.5 mass concentration data measured at Dazaifu were slightly (<2 mg m3) higher than those at Fukuoka University. This is probably due to the systematic difference of the instrumentations rather than the difference in locations. The volatilization loss of semi-volatile species in PM2.5 was anticipated more by TEOM than by a b-ray absorption gauge due to the difference in dehumidification methods, i.e., with or without heating. Appendix C. Disappearance of narrow-banded PM2.5 transport event on March 10, 2012, by the filter sampling in Fukuoka In Fig. 3b, no obvious increase in the PM2.5 aerosol components is recognizable on March 10. This is due to the coincidence of the

Chan, C.K., Yao, X., 2008. Air pollution in mega cities in China. Atmos. Environ. 42, 1e42. http://dx.doi.org/10.1016/j.atmosenv.2007.09.003. Chen, L.L., Carmichael, G.R., Hong, M.S., Ueda, H., Shim, S., Song, C.H., Kim, Y.P., Arimoto, R., Prospero, J., Savoie, D., Murano, K., Park, J.K., Lee, H.G., Kang, C., 1997. Influence of continental outflow events on the aerosol composition at Cheju Island, South Korea. J. Geophys. Res. Atmos. 102, 28551e28574. http:// dx.doi.org/10.1029/97jd01431. Cooper, O.R., Oltmans, S.J., Johnson, B.J., Brioude, J., Angevine, W., Trainer, M., Parrish, D.D., Ryerson, T.R., Pollack, I., Cullis, P.D., Ives, M.A., Tarasick, D.W., AlSaadi, J., Stajner, I., 2011. Measurement of western US baseline ozone from the surface to the tropopause and assessment of downwind impact regions. J. Geophys. Res. Atmos. 116. http://dx.doi.org/10.1029/2011jd016095. Hatakeyama, S., Ikeda, K., Hanaoka, S., Watanabe, I., Arakaki, T., Bandow, H., Sadanaga, Y., Kato, S., Kajii, Y., Zhang, D., Okuyama, K., Ogi, T., Fujimoto, N., Seto, T., Shimizu, A., Sugimoto, N., Takami, A., Aerial observations of air masses transported from East Asia to the Western Pacific: vertical structure of polluted air masses. Atmos. Environ. (in this issue). Hayami, H., 2005. Behavior of secondary inorganic species in gaseous and aerosol phases measured in Fukue Island, Japan, in dust season. Atmos. Environ. 39, 2243e2248. http://dx.doi.org/10.1016/j.atmosenv.2004.12.038. Hsu, S.-C., Liu, S.C., Jeng, W.-L., Lin, F.-J., Huang, Y.-T., Candice Lung, S.-C., Liu, T.-H., Tu, J.-Y., 2005. Variations of Cd/Pb and Zn/Pb ratios in Taipei aerosols reflecting long-range transport or local pollution emissions. Sci. Total Environ. 347, 111e 121. http://dx.doi.org/10.1016/j.scitotenv.2004.12.021. Huang, M., Carmichael, G.R., Adhikary, B., Spak, S.N., Kulkarni, S., Cheng, Y.F., Wei, C., Tang, Y., Parrish, D.D., Oltmans, S.J., D’Allura, A., Kaduwela, A., Cai, C., Weinheimer, A.J., Wong, M., Pierce, R.B., Al-Saadi, J.A., Streets, D.G., Zhang, Q., 2010. Impacts of transported background ozone on California air quality during the ARCTAS-CARB period e a multi-scale modeling study. Atmos. Chem. Phys. 10, 6947e6968. http://dx.doi.org/10.5194/acp-10-6947-2010. Hyogo Prefecture, 2011. Yearly variation of metallic elements in suspended particulate matter. In: White Paper on the Environment of Hyogo Prefecture 2011. http://www.kankyo.pref.hyogo.lg.jp/JPN/apr/hakusho/24hakusho/data/8_ kagaku_hp.pdf (in Japanese). Ikeda, K., Yamaji, K., Kanaya, Y., Taketani, F., Pan, X., Komazaki, Y., Kurokawa, J.-I., Ohara, T., 2013. Sensitivity analysis of source regions to PM2.5 concentration at Fukue Island, Japan. J. Air Waste Manag. Assoc. (in press). Itahashi, S., Uno, I., Yumimoto, K., Irie, H., Osada, K., Ogata, K., Fukushima, H., Wang, Z., Ohara, T., 2012. Interannual variation in the fine-mode MODIS aerosol optical depth and its relationship to the changes in sulfur dioxide emissions in China between 2000 and 2010. Atmos. Chem. Phys. 12, 2631e2640. http:// dx.doi.org/10.5194/acp-12-2631-2012. Kaneyasu, N., Takeuchi, K., Hayashi, M., Fujita, S., Uno, I., Sasaki, H., 2000. Outflow patterns of pollutants from East Asia to the North Pacific in the winter monsoon. J. Geophys. Res. Atmos. 105, 17361e17377. http://dx.doi.org/10.1029/ 2000jd900138. Kaneyasu, N., Takada, H., 2004. Seasonal variations of sulfate, carbonaceous species (black carbon and polycyclic aromatic hydrocarbons), and trace elements in fine atmospheric aerosols collected at subtropical islands in the East China Sea. J. Geophys. Res. Atmos. 109. http://dx.doi.org/10.1029/2003jd004137. Kaneyasu, N., 2010. Development of PM2.5 impactor for the conventional highvolume air sampler. J. Jpn. Soc. Atmos. Environ. 45, 171e174 (in Japanese). doi:10.11298/taiki.45.171. Kusunoki, K., Sakata, M., Tani, Y., Seike, Y., Ayukawa, K., 2012. Evaluating the contribution of long-range transport of heavy metals from the Asian continent to their concentrations in sediment cores from Lake Shinji, western Japan. Water Air Soil. Pollut. 223, 1151e1160. http://dx.doi.org/10.1007/s11270-0110932-4. Li, C., Zhang, Q., Krotkov, N.A., Streets, D.G., He, K., Tsay, S.-C., Gleason, J.F., 2010. Recent large reduction in sulfur dioxide emissions from Chinese power plants observed by the ozone monitoring instrument. Geophys. Res. Lett. 37, L08807. http://dx.doi.org/10.1029/2010GL042594. Li, P., Xin, J., Wang, Y., Wang, S., Li, G., Pan, X., Liu, Z., Wang, L., 2013. The acute effects of fine particles on respiratory mortality and morbidity in Beijing, 2004e2009.

Please cite this article in press as: Kaneyasu, N., et al., Impact of long-range transport of aerosols on the PM2.5 composition at a major metropolitan area in the northern Kyushu area of Japan, Atmospheric Environment (2014), http://dx.doi.org/10.1016/j.atmosenv.2014.01.029

10

N. Kaneyasu et al. / Atmospheric Environment xxx (2014) 1e10

Environ. Sci. Pollut. Res. 20, 6433e6444. http://dx.doi.org/10.1007/s11356-0131688-8. Lu, Z., Streets, D.G., Zhang, Q., Wang, S., Carmichael, G.R., Cheng, Y.F., Wei, C., Chin, M., Diehl, T., Tan, Q., 2010. Sulfur dioxide emissions in China and sulfur trends in East Asia since 2000. Atmos. Chem. Phys. 10, 6311e6331. http:// dx.doi.org/10.5194/acp-10-6311-2010. Mori, A., Utsunomiya, A., Uno, I., Wakamatsu, S., Ohara, M., 1997. Analysis of aerosol concentration variation and high concentration episodes observed in the northern Kyushu area. J. Jpn. Soc. Atmos. Environ. 32, 73e89 (in Japanese). doi: 10.11298/taiki1995.32.73. Mukai, H., Ambe, Y., Shibata, K., Muku, T., Takeshita, K., Fukuma, T., Takahashi, J., Mizota, S., 1990. Long-term variation of chemical composition of atmospheric aerosol on the Oki Islands in the Sea of Japan. Atmos. Environ. A. General. Top. 24, 1379e1390. http://dx.doi.org/10.1016/0960-1686(90)90044-N. Oishi, O., Fujikawa, K., Ymamoto, S., Iwamoto, S., 2009. Yearly change of chemical composition in precipitation, gaseous pollutants, and aerosol in Fukuoka prefecture. In: Proceeding of the 9th Annual Meeting of the Kyushu Branch, Japan Society of Atmospheric Environment, pp. 25e26 (in Japanese). Branch office: Fukuoka Institute of Health and Environmental Sciences, 39 Mukaizano, Dazaifu, Fukuoka 818-0135, Japan. Ohara, T., Akimoto, H., Kurokawa, J., Horii, N., Yamaji, K., Yan, X., Hayasaka, T., 2007. An Asian emission inventory of anthropogenic emission sources for the period 1980e2020. Atmos. Chem. Phys. 7, 4419e4444. http://dx.doi.org/10.5194/acp7-4419-2007. Okuda, T., Katsuno, M., Naoi, D., Nakao, S., Tanaka, S., He, K., Ma, Y., Lei, Y., Jia, Y., 2008. Trends in hazardous trace metal concentrations in aerosols collected in Beijing, China from 2001 to 2006. Chemosphere 72, 917e924. http://dx.doi.org/ 10.1016/j.chemosphere.2008.03.033. Okuda, T., Takada, H., Kumata, H., Nakajima, F., Hatakeyama, S., Uchida, M., Tanaka, S., He, K.B., Ma, Y.L., 2013. Inorganic chemical characterization of

aerosols in four Asian mega-cities. Aerosol Air Qual. Res. 13, 436e449. http:// dx.doi.org/10.4209/aaqr.2012.09.0250. Pan, Y., Wang, Y., Sun, Y., Tian, S., Cheng, M., 2013. Size-resolved aerosol trace elements at a rural mountainous site in Northern China: Importance of regional transport. Sci. Total Environ. 461e462, 761e771. http://dx.doi.org/10.1016/ j.scitotenv.2013.04.065. Park, M.H., Kim, Y.P., Kang, C.-H., Shim, S.-G., 2004. Aerosol composition change between 1992 and 2002 at Gosan, Korea. J. Geophys. Res. Atmos. 109, D19S13. http://dx.doi.org/10.1029/2003JD004110. Parrish, D.D., Aikin, K.C., Oltmans, S.J., Johnson, B.J., Ives, M., Sweeny, C., 2010. Impact of transported background ozone inflow on summertime air quality in a California ozone exceedance area. Atmos. Chem. Phys. 10, 10093e10109. http:// dx.doi.org/10.5194/acp-10-10093-2010. Shang, Y., Sun, Z.W., Cao, J.J., Wang, X.M., Zhong, L.J., Bi, X.H., Li, H., Liu, W.X., Zhu, T., Huang, W., 2013. Systematic review of Chinese studies of short-term exposure to air pollution and daily mortality. Environ. Int. 54, 100e111. http://dx.doi.org/ 10.1016/j.envint.2013.01.010. Shimohara, T., Oishi, O., Utsunomiya, A., Mukai, H., Hatakeyama, S., Eun-Suk, J., Uno, I., Murano, K., 2001. Characterization of atmospheric air pollutants at two sites in northern Kyushu, Japan e chemical form, and chemical reaction. Atmos. Environ. 35, 667e681. http://dx.doi.org/10.1016/S1352-2310(00)00340-X. Takami, A., Miyoshi, T., Shimono, A., Kaneyasu, N., Kato, S., Kajii, Y., Hatakeyama, S., 2007. Transport of anthropogenic aerosols from Asia and subsequent chemical transformation. J. Geophys. Res. Atmos. 112, D22S31. http://dx.doi.org/10.1029/ 2006JD008120. Yonemochi, S., Chen, X., Miao, P., Lu, S., Oh, K., Umezawa, N., 2013. Characterization of high concentration of PM2.5 and PM1 collected in Beijing in January, 2013. J. Jpn. Soc. Atmos. Environ. 48, 140e143 (in Japanese). doi:10.11298/taiki.48.140.

Please cite this article in press as: Kaneyasu, N., et al., Impact of long-range transport of aerosols on the PM2.5 composition at a major metropolitan area in the northern Kyushu area of Japan, Atmospheric Environment (2014), http://dx.doi.org/10.1016/j.atmosenv.2014.01.029