The spatiotemporal distribution and chemical composition of atmospheric fine particles in areas around the Taiwan Strait were firstly investigated. Fine particles (PM2.5) were simultaneously collected at two sites on the west-side, one site at an offshore island, and three sites on the east-side of the Taiwan Strait in 2013–2014. Field sampling results indicated that the average PM2.5 concentrations at the west-side sampling sites were generally higher than those at the east-side sampling sites. In terms of chemical composition, the most abundant water-soluble ionic species of PM2.5 were SO42−, NO3−, and NH4+, while natural crustal elements dominated the metallic content of PM2.5, and the most abundant anthropogenic metals of PM2.5 were Pb, Ni and Zn. Moreover, high OC/EC ratios of PM2.5 were commonly observed at the west-side sampling sites, which are located at the downwind of major stationary sources. Results from CMB receptor modeling showed that the major sources of PM2.5 were anthropogenic sources and secondary aerosols at the both sides, and natural sources dominated PM2.5 at the offshore site. A consistent decrease of secondary sulfate and nitrate contribution to PM2.5 suggested the transportation of aged particles from the west-side to the east-side of the Taiwan Strait.

The objective of this study was to characterize the chemical properties of atmospheric particles sampled in the KinmenXiamen Airshed located on the west bank of the Taiwan Strait. Seven particulate matter (PM) sampling sites in the KinmenXiamen Airshed, including three sites at Kinmen Island and four in urban Xiamen, were selected for this particular study. Regular sampling was conducted to collect PM 10 with high-volume samplers twice a month from March 2008, while intensive sampling was conducted to collect PM 2.5 and PM 2.5-10 with dichotomous samplers and PM 10 with high-volume samplers in the spring and winter of [2008][2009]. After sampling, the metallic contents of PM 10 were analyzed with an inductively coupled plasma-atomic emission spectrometer (ICP-AES). Ionic species and carbonaceous contents of PM 10 were analyzed with an ion chromatograph (IC) and elemental analyzer (EA), respectively. Finally, the source identification and apportionment of PM were analyzed by principal component analysis (PCA) and receptor modeling (CMB), respectively. The results from PM 10 sampling indicated that atmospheric aerosol particles had a tendency to accumulate in Xiamen Bay all year round, particularly in spring and winter. The five sampling sites at the center of Xiamen Bay had relatively higher PM 10 concentrations than the two sampling sites outside Xiamen Bay, suggesting that local emissions from Xiamen Bay were more significant than emissions transported over a long distance by the Northeastern Monsoon. The phenomenon of superimposition was regularly observed during air pollution episodes at Xiamen Bay. Moreover, the results of chemical analysis showed that the main chemical components of the PM were SO 4 2-, NO 3 -, NH 4 + , OC, and EC and crustal elements (Ca, Mg, Fe, and Al) in the aerosol particles in the Kinmen-Xiamen Airshed. The neutralization ratios (NR) of PM were generally smaller than unity, indicating that the atmospheric particulates were mostly acidic. The averaged sulfur oxidation ratio (SOR) ranged from 0.20 to 0.51, and the nitrogen oxidation ratio (NOR) ranged from 0.10 to 0.41 for all seasons. The ratios of sulfur and nitrogen oxidation were generally higher than 0.25 and 0.10, respectively, suggesting that secondary sulfate and nitrate aerosols came mainly from across-boundary transportation and could be further accumulated in the Kinmen-Xiamen Airshed. The results from CMB receptor modeling showed that the major sources of atmospheric PM 10 in the Kinmen-Xiamen Airshed were soil dusts, secondary aerosols, the petroleum industry, motor vehicle exhausts, the iron and steel industry, the cement industry, diesel vehicle exhausts, marine aerosols, and biomass burning.

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This study investigated the diurnal variation of mass concentration and chemical composition of atmospheric aerosol particles sampled at Xiamen Bay, located on the west bank of the Taiwan Strait. Atmospheric PM 10 samples were collected at ten particulate matter (PM) sampling sites at Xiamen Bay, including five sites at the Kinmen Islands and five sites in urban Xiamen, at both daytime and nighttime during the regular and intensive sampling periods. Regular sampling was conducted to collect PM 10 with high-volume samplers three times a month from April 2009 to April 2010, while intensive sampling was conducted to collect PM 2.5 and PM 2.5-10 with dichotomous samplers in the spring and winter of 2009 and 2010. This study further selected ten major emission sources (e.g., stone processing, power plants, soil dusts, and biomass burning) at Xiamen Bay to collect fugitive particulate samples which were then resuspended in a self-designed resuspension chamber to collect PM 2.5 and PM 2.5-10 with two separate dichotomous samplers for further chemical analysis.The results from PM 10 sampling indicated that atmospheric aerosol particles tended to be accumulated in Xiamen Bay all year round, but especially in spring and winter. A significant diurnal variation of PM 10 was observed, with higher PM 10 concentrations in the daytime during the regular sampling periods. The chemical analysis results showed that the major chemical components of PM 10 were SO 4 2-, NO 3 -, NH 4 + , OC, EC, and crustal elements (Ca, Mg, Fe, and Al), which were usually higher in the daytime than at night at Xiamen Bay. The differences were most pronounced at night, where the concentrations of most anthropogenic elements (Ni, Cu, As, and V) were higher than those in the daytime. The elemental composition of PM emitted from stone processing and the cement industry were dominated by crustal elements, particularly Ca, whereas the profile of top-soil mainly contained Al and Ca. The profiles of industrial sources were dominated by secondary inorganic aerosols and EC. Moreover, construction and road dusts contained large amounts of Fe and Al, while biomass burning released large amounts of K, OC, and SO 4 2-.

This study aims to investigate the spatiotemporal variation, chemical composition, and source apportionment of marine fine particles (PM2.5) as well as their regional transport toward the Matsu Islands located near the coastline of northwestern Taiwan Strait. Four offshore island sites located at the Matsu Islands were selected to conduct both regular and intensive sampling of marine PM2.5. Water-soluble ionic species, metallic elements, and carbonaceous contents were then analyzed to characterize the chemical characteristics of marine PM2.5. In order to identify the potential sources and their contributions to marine PM2.5, chemical mass balance (CMB) receptor model was employed along with the backward trajectory simulation to resolve the source apportionment of marine PM2.5 and to explore their transport routes in different seasons. The results showed that high PM2.5 concentrations were commonly observed during the northeastern monsoon periods. Additionally, marine PM2.5 concentration decreased from the west to the east with the highest PM2.5 at the Nankang Island and the lowest PM2.5 at the Donyin Island in all seasons, indicating an obvious concentration gradient of PM2.5 transported from the continental areas to the offshore islands. In terms of chemical characteristics of PM2.5, the most abundant water-soluble ions of PM2.5 were secondary inorganic aerosols (SO42−, NO3−, and NH4+) which accounted for 55–81% of water-soluble ions and 29–52% of marine PM2.5. The neutralization ratios of PM2.5 were always less than unity, indicating that NH4+ cannot solely neutralize nss-SO42+ and NO3− in marine PM2.5 at the Matsu Islands. Although crustal elements (Al, Ca, Fe, K, and Mg) dominated the metallic content of marine PM2.5, trace anthropogenic metals (Cd, As, Ni, and Cr) increased significantly during the northeastern monsoon periods, particularly in winter. Organic carbons (OCs) were always higher than elemental carbons (ECs), and the mass ratios of OC and EC were generally higher than 2.2 in all seasons, implying that PM2.5 was likely to be aged particles. During the poor air quality periods, major air mass transport routes were the northern transport and the anti-cyclonic circulation routes. Source apportionment results indicated that fugitive soil dusts and secondary aerosols were the major sources of marine PM2.5 at the Matsu Islands, while, in winter, biomass burning contributed up to 15% of marine PM2.5. This study revealed that cross-boundary transport accounted for 66~84% of PM2.5 at the Matsu Islands, suggesting that marine PM2.5 at the Matsu Islands has been highly influenced by anthropogenic emissions from neighboring Fuzhou City as well as long-range transport from Northeast Asia.

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The spatiotemporal variation, chemical fingerprints, transportation routes, and source apportionment of atmospheric fine particles (PM 2.5 ) along the coastal region of southern Taiwan were investigated at three environments in the tip of southern Taiwan. Three representative sampling sites at Chien-Chin (urban site), Siao-Gang (industrial site) and Che-Cheng (background site) were selected for simultaneous PM 2.5 sampling from December 2014 to May 2015. Regular sampling of 24-h PM 2.5 was conducted for continuous 6-9 days in each month. After sampling, the chemical composition, including water-soluble ions, metallic elements and the carbonaceous content of PM 2.5 , was further analyzed within two weeks. The levoglucosan concentration was further compared to OC and K + in PM 2.5 originating from biomass burning. Moreover, the potential sources of PM 2.5 and their respective contribution were further resolved by backward trajectory simulation, combined with chemical mass balance (CMB) receptor modeling. The field sampling results indicated that the PM 2.5 concentrations at the urban and industrial sites were always higher than those at the background site. The most abundant water-soluble ionic species of PM 2.5 are SO 4 2-, NO 3 -and NH 4 + , implying that PM 2.5 is mainly composed of secondary ammonium sulfate and ammonium nitrate. The most abundant metallic elements of PM 2.5 included crustal elements (Al, Fe and Ca) and anthropogenic (generated by humans) elements (V, Ni, As, Cd, Zn and Pb). Moreover, the concentrations of OC and EC at the Chien-Chin and Siao-Gang sites were generally higher than those at the Che-Cheng site, mainly due to the emissions from urban and industrial anthropogenic sources. Vehicular exhausts and industrial emissions were the main sources of PM 2.5 at the Chien-Chin and Siao-Gang sites, respectively, while biomass burning and soil dusts were the dominant sources of PM 2.5 at the Che-Cheng site.

Marine fine aerosols were simultaneously collected over sea and at offshore islands during three cruise sampling campaigns to investigate the spatial distribution of atmospheric fine particles (PM_2.5) and the influences of sea salts and anthropogenic particles on the chemical characteristics of PM_2.5 in the Taiwan Strait. Field sampling results indicated that PM_2.5 concentrations over sea were generally higher than those at the offshore islands, while the PM_2.5 concentrations in the daytime were commonly higher than those at nighttime. Moreover, the concentrations of PM_2.5 were generally higher than those of coarse particles (PM_{2.5–10}) with an exception of the winter cruise in 2014. Moreover, sea salts accounted for 6.5–11.1 % and 11.0–13.5 % of PM_2.5 at the offshore islands and over sea, respectively. The contributions of non-sea salt-water soluble ions (nss-WSI) to PM_2.5 at the offshore islands were obviously higher than those over sea, while the contributions of ss-WSI for PM_2.5 at the offshore islands were much lower than those over sea during the cruise sampling campaigns. Anthropogenic metallic elements including Zn, Mn, Pb, Cr, and Ni had higher concentrations over sea than those at the offshore islands, suggesting that PM_2.5 was not only influenced by marine aerosols but also by anthropogenic particles originated from human activities such as industrial processing, fuel burning, and vehicular and shipping exhausts. Higher mass ratios of Ni/Al and Ni/Fe over sea than those at the offshore islands suggested that shipping emissions had higher influences on marine fine particles than crustal dusts in open sea while compared to those at the offshore islands. The carbonaceous contents of PM_2.5 indicated that the concentrations of organic carbons (OC) were generally higher than those of elemental carbons (EC). The higher mass ratios of organic and elemental carbons (OC/EC) were observed at the central and north Taiwan Strait, and follow by the offshore islands and the south Taiwan Strait. Overall, sea salts and anthropogenic particles had significant influences on the chemical composition of PM_2.5 over sea and at the offshore islands.