Chemical characteristics and spatiotemporal variation of marine fine particles for clustered channels of air masses transporting toward remote background sites in East Asia.

This study investigated the chemical characteristics, spatiotemporal distribution, and source apportionment of marine fine particles (PM2.5) for clustered transport channels/routes of air masses moving toward three remote sites in East Asia. Six transport routes in three channels were clustered based on backward trajectory simulation (BTS) in the order of: West Channel > East Channel > South Channel. Air masses transported toward Dongsha Island (DS) came mainly from the West Channel, while those transported toward Green Island (GR) and Kenting Peninsula (KT) came mostly from the East Channel. High PM2.5 commonly occurred from late fall to early spring during the periods of Asian Northeastern Monsoons (ANMs). Marine PM2.5 was dominated by water-soluble ions (WSIs) which were predominated by secondary inorganic aerosols (SIAs). Although the metallic content of PM2.5 was predominated by crustal elements (Ca, K, Mg, Fe, and Al), enrichment factor clearly showed that trace metals (Ti, Cr, Mn, Ni, Cu, and Zn) came mainly from anthropogenic sources. Organic carbon (OC) was superior to elemental carbon (EC), while OC/EC and SOC/OC ratios in winter and spring were higher than those in other two seasons. Similar trends were observed for levoglucosan and organic acids. The mass ratio of malonic acid and succinic acid (M/S) was commonly higher than unity, showing the influences of biomass burning (BB) and secondary organic aerosols (SOAs) on marine PM2.5. We resolved that the main sources of PM2.5 were sea salts, fugitive dust, boiler combustion, and SIAs. Boiler combustion and fishing boat emissions at the site DS had higher contribution than those at the sites GR and KT. The highest/lowest contribution ratios of cross-boundary transport (CBT) were 84.9/29.6% in winter and summer, respectively.

Long-range transport of atmospheric speciated mercury from the eastern waters of Taiwan Island to northern South China Sea.

This study explored the temporospatial distribution, gas-particle partition, and pollution sources of atmospheric speciated mercury (ASM) from the eastern offshore waters of the Taiwan Island (TI) to the northern South China Sea (SCS). Both gaseous and particulate mercury were simultaneously sampled at three remote sites in four seasons. The average concentrations of gaseous elemental mercury (GEM), gaseous oxidized mercury (GOM), and particulate bound mercury (PBM) were 2.05 ± 0.45 ng/m3, 19.17 ± 5.39 pg/m3, and 0.11 ± 0.06 ng/m3, respectively. The concentrations of GEM and PBM in the cold seasons were higher than those in the warm seasons, but those of GOM had an opposite trend. In terms of gas-solid partition, ASM was apportioned as 91.3-97.3% of GEM and 2.7-8.7% of GOM and PBM. The average concentrations of GEM, GOM, and PBM at the Green Island (GI) were 2.21 ± 0.47 ng/m3, 22.31 ± 5.35 pg/m3, and 0.12 ± 0.06 ng/m3; those at the Kenting Peninsula (KT) were 2.11 ± 0.43 ng/m3, 20.57 ± 4.38 pg/m3, and 0.11 ± 0.06 ng/m3; and those at the Dongsha Islands (DS) were 1.84 ± 0.40 ng/m3, 15.19 ± 3.58 pg/m3, and 0.08 ± 0.05 ng/m3, respectively. Overall, the spatial distribution of ASM concentrations showed the order as: GI > KT > DS. Air masses blown mainly from the West Pacific Ocean (WPO) and SCS in summer showed the lowest ASM concentrations. Oppositely, high ASM concentrations were commonly observed in spring and winter when polluted air masses were blown by Asian Northeastern Monsoons (ANMs). The transport routes of polluted air masses were originated mainly from North China, Central China, Northeast China, Korea and Japan, and mostly passed through the urban and industrial regions in the northeastern Asian countries.

Inter-comparison of chemical fingerprint and source apportionment of marine fine particles at two islands through the west and east passages of the Taiwan Island.

In this study, the concentrations of marine fine particles (PM2.5) and their chemical fingerprints were inter-compared at two islands located aside from the west and east waters of Taiwan Island and the variability of west and east passages (i.e., Routes A1 and A2) were explored. Marine PM2.5 was simultaneously sampled at the Green and Dongsha Islands and five chemical components (i.e., water-soluble ions, metallic elements, carbonaceous content, anhydrosugars, and organic acids) were further analyzed in PM2.5 to characterize their chemical fingerprints. The highest concentrations of chemical composition and PM2.5 were commonly observed during the Asian Northeastern Monsoons (ANMs) via long-range transport (LRT). Water-soluble ions (WSIs) were dominated by secondary inorganic aerosols (SIAs), and followed by oceanic spray. The major metallic content of PM2.5 was crustal elements, while trace metals originated from anthropogenic sources with an enrichment factor (EF) > 10. In terms of carbonaceous content in PM2.5, organic carbon (OC) was superior to elemental carbon (EC). High levoglucosan concentrations were also observed during the periods of ANMs. Secondary organic aerosols (SOAs) were formed by atmospheric chemical reactions during the LRT procedure. The PM2.5 concentration of Route A1 was 37.51 % higher than that of Route A2, and trace metals (V, Mn, Ni, Pb, Cr, and Cu) increased significantly by 96.16-325.83 %. Positive matrix factorization (PMF) results revealed that the dominant factor of PM2.5 for Route A1 was shipping emissions and vehicular exhausts (41.2 %), while that for Route A2 was oceanic spray (30.2 %). Route A1 was mainly attributed to highly industrialized regions, densely populated urbanized areas, and ship-intensive traffics in East Asia.

Seasonal variation and source identification of atmospheric speciated mercury in an industrial harbor area in East Asia.

In this study, the pollution characteristics, spatiotemporal variation, and potential sources of atmospheric speciated mercury (ASM) in an industrial harbor area were explored. Gaseous elemental mercury (GEM), gaseous oxidized mercury (GOM), and particle-bound mercury (PBM) were sampled by a self-designed manual system at three harbor sites in four seasons. The yearly average concentrations of GEM, GOM, and PBM were 6.7 ± 2.0 ng/m3, 244 ± 70 pg/m3, and 410 ± 105 pg/m3, respectively. The seasonal average ASM concentration was in the order of: winter > fall > spring > summer. In terms of species, GEM dominated ASM, while reactive mercury (RM = GOM + PBM) accounted for 6.0-15.7%of ASM, implying that ASM was governed by anthropogenic sources in the harbor area. The highest ASM concentrations were observed at Site Zhonghe (ZH), which is mainly influenced by both ship exhausts and industrial emissions, and positively correlated with CO, NOx, and SO2. In particular, GOM was positively correlated with O3, and negatively correlated with air temperature and relative humidity, showing high impact from atmospheric photochemical reactions. Air masses transporting westerly in spring were mainly from ship exhausts. In summer, air masses transporting from the south were from utility power plants and machinery exhausts. In fall and winter, air masses were transported mainly from the north, blowing by the long-range transport of polluted air masses originated from the north. Both principal component analysis and positive matrix factorization results indicate that coal burning, industrial emissions, and vehicular exhausts are the main contributors to ASM. Site Zhongdao (ZD) was close to the bulk carrier loading and unloading zones and was highly influenced by mobile sources, while Site ZH was mainly influenced by the neighboring industrial complex.

Temporal variation and potential origins of atmospheric speciated mercury at a remote island in South China Sea based on two-year field measurement data.

This study explored the temporal variation, gas-particle partition, and potential origins of atmospheric speciated mercury at a remote island in the South China Sea. Two-year data of three mercury species was measured at the Taiping Island. Air masses were clustered into five transport routes (A-E) to resolve the potential origins of atmospheric mercury. Field measurement showed that the concentration of gaseous elemental mercury (GEM) (1.33 ± 0.52 ng/m3) was close to the GEM background level of Northern Hemisphere, while those of GOM and PHg were 13.39 ± 3.58 and 94.33 ± 30.25 pg/m3, respectively. Both regular and intensive samplings concluded a consistent trend of higher mercury level in winter and spring than that in summer and fall. GEM dominated atmospheric mercury in all seasons (86.2-98.5%), while the highest partition of particle-bound mercury (PHg) was observed in winter (13.8%). The highest GEM concentrations were observed for Route A originating from central China and western Taiwan Island, and followed by Routes D and E from the Philippines, Malaysia, and Indonesia, while the lowest concentrations of GEM were observed for Routes B and C originating from North China, Korea, and Japan. Most importantly, high correlation of GEM versus levoglucosan and K+ in PM2.5 (r = 0.764 and 0.758, p < 0.01) confirmed that GEM was mainly emitted from biomass burning sources at the surrounding countries.