[1] An intensive spring aerosol sampling campaign over northwestern and northern China and a megacity in eastern China was conducted in the spring of 2007 to investigate the mixing of Asian dust with pollution aerosol during its long-range transport. On the basis of the results of the three sites near dust source regions (Tazhong, Yulin, and Duolun) and a metropolitan city (Shanghai), three dust sources, i.e., the western high-Ca dust in the Taklimakan Desert, the northwestern high-Ca dust and the northeastern low-Ca dust in Mongolia Gobi, were identified on the basis of the air mass trajectories and the elemental tracer analysis (e.g., Ca/Al, SO 4 2− /S, Ca 2+ /Ca, and Na + /Na). The western dust was least polluted in comparison to the other two dust sources. The results evidently indicated that the dust could have already mixed with pollution aerosol even in near dust source regions. The concentrations of As, Cd, Cu, Pb, Zn, and S were elevated several times at all sites during dust days, showing the entrainment of pollution elements by dust. The secondary SO 4 2− was observed to show much higher concentration due to the heterogeneous reaction on the alkaline dust during dust storm, while the concentrations of NO 3 − and NH 4 + decreased owing to the dilution of the local pollution by the invaded dust. The western dust contained relatively low anthropogenic aerosols, and it mainly derived from the Taklimakan Desert, a paleomarine source. The northwestern dust had a considerable chemical reactivity and mixing with sulfur precursors emitted from the coal mines on the pathway of the long-range transport of dust. The northeastern dust reached Shanghai with high acidity, and it became the mixed aerosol with the interaction among dust, local pollutants, and sea salts. Comparison of the speciation of the water-soluble ions on both nondust and dust days at all sites illustrated the evolution of major ion species from different dust sources during the long-range transport of dust. The mixing mechanisms of the dust with the pollution aerosol on the local, medium-range, and long-range scale revealed from this study would improve the understanding of the impacts of Asian dust on the regional/global climate change.
TSP and PM2.5 aerosol particles were synchronously sampled at six sites along the transport pathway of dust storms from desert regions to coastal areas in the spring of 2004 to investigate the regional characteristics of Asian dust and its impact on aerosol chemistry over northern China. Factor analysis of daily PM10 concentrations in 17 cities showed that northern China can be basically divided into five regions: (1) Northern Dust Region, (2) Northeastern Dust Region, (3) Western Dust Region, (4) Inland Passing Region, and (5) Coastal Region. Northern Dust Region was characterized by a high content of Ca. Northeastern Dust Region was a relatively clean area with a low concentration of pollutants and secondary ions in comparison to other regions. Inland Passing Region and Coastal Region showed high concentrations of anthropogenic pollutants. The impact of Asian dust on aerosol chemistry decreased in the order Yulin/Duolun > Beijing > Qingdao/Shanghai as transport distance increased. The ratio of Ca/Al, which showed significant differences in different regions over northern China, is suggested to be a tracer to identify the sources of dust storms. Asian dust either mixes pollutants on the pathway and carries them to the downwind regions or dilutes the pollutants over northern China, which affects the aerosol composition more in coarse particles in those areas near source regions and more in fine particles in downwind areas. The ratio of NO3−/SO42− during dust storms was significantly reduced and the lowest generally appeared after the peak of dust. Our results showed that Asian dust plays a critical role in buffering the acidity of aerosols over northern China by a potential increase of ∼1 unit pH for the aerosol particles in spring.
PM (particulate matter less than 2.5 μm in diameter) is considered as a harmful carcinogen. Determining the precise relationship between the chemical constituents of PM in the air and cancer progression could aid the treatment of environment related disease and establishing risk reduction strategies. Herein, we used transcriptomics (RNA-seq) and an integrated microfluidic system to identify the global gene expression and differential target proteins expression induced by ambient fine particles collected from the heavy haze in China. The results clearly indicated that cancer related pathways exhibited the strongest dysregulation. The ambient fine particles could be uptaken into the cells by pinocytosis, mainly promoting the PI3K-Akt pathway, FGF/FGFR/MAPK/VEGF signaling, and the JAK-STAT pathway, leading to evading apoptosis, sustained angiogenesis, and cell proliferation, which are the most important hallmarks of cancer. And fine particles also have been demonstrated to create intracellular reactive oxygen species (ROS) and mitochondrial ROS, change intracellular free Ca, and induce apoptosis, which are all key players in mediating cancer progression. It was observed by transmission electron microscopy (TEM) that the particles from the haze could enter the mitochondria, resulting in disturbance of the mitochondrial membrane and disruption of the mitochondria, and these particles can even enter inside the nucleus. It was also found in our study of organics (OC, PAHs) and metals (Zn, As, V) that compounds of fine particles were more closely associated with the exacerbation of cancer and secondary aerosols generated by traffic had the largest impact on cancer related signal transductions.
Daily particulate matter with particles less than 2.5 μm in aerodynamic diameter (PM2.5) and total suspended particulates (TSP) were analyzed for chemical composition and daily PM10, SO2, and NO2 were monitored by automatic monitoring systems on the seven sites over China along the pathway of the long‐range transport of the dust from 20 March to 19 April 2007. The highest recorded dust and daily Air Pollution Index topped 500 for the first time since 2002, when the routine continuous monitoring of PM10 was initiated in Shanghai. The daily 24 h average PM10 concentration of 648 μg m−3 was observed on 2 April 2007. The ratios of SO2/PM10, NO2/PM10, and PM2.5/PM10 were 0.066, 0.077, and 15.5% on 2 April 2007, which were significantly different from the nondust day and could be used as the index to judge the occurrence of dust in Shanghai. On the peak dusty day, the ratios of crustal matter rose to 70% and 64% of the total mass of PM2.5 and TSP, respectively, while the ratios were 13% and 37% on nondust days. The ratio of Ca/Al in the dust aerosol in Shanghai was much closer to that in Duolun and Yulin near Mongolia Gobi rather than that in Tazhong of Taklimakan desert, indicating that the dust was transported from Mongolia Gobi instead of Taklimakan desert in Xinjiang province. The compositions of sea salt aerosol in PM2.5 and TSP, combined with back trajectories, indicated that the dust passed through the East China Seas before reaching Shanghai, which is one of the typical dust pathways that lead to heavily polluted days in Shanghai due to dust transport. The anthropogenic sources along the pathway also partially contributed to the PM pollution in Shanghai during this dust event.
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