Aerosol composition at a coastal monitoring site in Hong Kong-initial results

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A study of the chemical composition and transport of marine aerosols over the ocean near China

In this paper the authors cite the aerosol samples collected with a KA-200 Anderson cascade Impactor and a KB-120 sampler during the first cruise of the Kuroshio investigation operated by the People's Republic of China and Japan cooperative program, from July 23 to August 21, 1987. The concentration size distributions and composition of marine aerosols over the Kuroshio area are analyzed. Neutron activation analysis is used to determine the elemental composition of the aerosols. The authors also discuss some characteristics of marine aerosols relating to long-range transport of crustal and anthropogenic elements from the continent to the remote ocean. Analytical results indicate that elements Al, Fe, Sc and Sb over this area are obviously influenced by the continent of Asia, and the size distributions are changed after long-range transport. The concentration of large particles increase. The concentrations of the elements C1 and Na are closely related to ocean conditions; the source of the elements Cl and Na is mainly the ocean. Besides coal combustion, the ocean is also a very important source for the element Se. The amount of Se is related to the distribution of marine life.

Aerosol characterization in a city in central China plain and implications for emission control

Extensive studies on aerosol chemistry have been carried out in megacities in China,however,aerosol characterization in Central China Plain(CCP)is limited.Here we conducted real-time measurements of fine particle composition with a time-of-flight aerosol chemical speciation monitor in Kaifeng,Henan province in October 2019.Our results showed that nitrate and organics constituted the major fraction of non-refractory PM_(2.5)for the entire study,on average accounting for 34%and 33%,respectively.However,aerosol composition was substantially different among four periods due to different meteorological conditions and chemical processing.For instance,nitrate presented the lowest contribution during the first period due to evaporative loss associated with high temperature(T),and then rapidly increased during polluted periods as a function of relative humidity(RH).Positive matrix factorization analysis showed the dominance of secondary organic aerosol(SOA)in OA,and also the changes in OA composition under different T and RH levels.In addition,this study is unique with two periods of local emission controls.Back trajectory and coefficient of divergence analysis showed that air pollution in CCP was overall homogeneously distributed.As a result,the effectiveness of local emission controls in this region was strongly affected by meteorological conditions and regional transport.We found that one of the periods with emission control even showed the highest concentrations for the entire study.Our results point towards the limited effect of local emission controls in mitigating air pollution in CCP,and highlight the importance of joint emission controls under unfavorable meteorological conditions.

Humidity and PM_(2.5) composition determine atmospheric light extinction in the arid region of northwest China

Atmospheric visibility can directly reflect the air quality.In this study,we measured watersoluble ions(WSIs),organic and element carbon(OC and EC)in PM 2.5 from September 2017 to August 2018 in Urumqi,NW China.The results show that SO4^2-,NO 3^(-)and NH4^(+)were the major WSIs,together accounting for 7.32%-84.12%of PM 2.5 mass.Total carbon(TC=OC+EC)accounted for 12.12%of PM 2.5 mass on average.And OC/EC>2 indicated the formation of secondary organic carbon(SOC).The levels of SO4^2-,NO3^(-)and NH4^(+)in low visibility days were much higher than those in high visibility days.Relative humidity(RH)played a key role in affecting visibility.The extinction coefficient(b ext)that estimated via Koschmieder formula with visibility was the highest in winter(1441.05±739.95 Mm-1),and the lowest in summer(128.58±58.00 Mm^(-)1).The b ext that estimated via IMPROVE formula with PM 2.5 chemical component was mainly contributed by(NH 4)2 SO4 and NH4 NO3.The b ext values calculated by both approaches presented a good correlation with each other(R^2=0.87).Multiple linear regression(MLR)method was further employed to reconstruct the empirical regression model of visibility as a function of PM 2.5 chemical components,NO_(2) and RH.The results of source apportionment by Positive Matrix Factorization(PMF)model showed that residential coal combustion and vehicle emissions were the major sources of b ext.

Sources and characteristics of fine particles over the Yellow Sea and Bohai Sea using online single particle aerosol mass spectrometer

Marine aerosols over the East China Seas are heavily polluted by continental sources. During the Chinese Comprehensive Ocean Experiment in November 2012, size and mass spectra of individual atmospheric particles in the size range from 0.2 to 2.0 μm were measured on board by a single particle aerosol mass spectrometer （SPAMS）. The average hourly particle number （PN） was around 4560 ＋ 3240 in the South Yellow Sea （SYS）, 2900 ± 3970 in the North Yellow Sea （NYS）, and 1700 ± 2220 in the Bohai Sea （BS）. PN in NYS and BS varied greatly over 3 orders of magnitude, while that in SYS varied shghtly. The size distributions were fitted with two log-normal modes. Accumulation mode dominated in NYS and BS, especially during episodic periods. Coarse mode particles played an important role in SYS. Particles were dassifled using an adaptive resonance theory based neural network algorithm （ART-2a）. Six particle types were identified with secondary-containing, aged sea-salt, soot-like, biomass burning, fresh sea-salt, and lead-containing particles accounting for 32%, 21%, 18%, 16%, 4%, and 3% of total PN, respectively. Aerosols in BS were relatively enriched in particles from anthropogenic sources compared to SYS, probably due to emissions from more developed upwind regions and indicating stronger influence of continental outflow on marine environment. Variation of source types depended mainly on origins of transported air masses. This study examined rapid changes in PN, size distribution and source types of fine particles in marine atmospheres. It also demonstrated the effectiveness of hi,h-time-resolution source apportionment by ART-2a.

Effects of Composite Xinyi Aerosol (复方辛夷雾化剂) on Asthma Related Cytokines in Serum and Sputum of Patients with Bronchial Asthma

Objective: To observe the therapeutic effect of composite Xinyi ae rosol (复方辛夷雾化剂, XYA) in treating asthma and its influence on asthma relat ed cytokines in serum and sputum of patients with mild or moderate bronchial ast hma.Methods: Sixty patients were divided randomly into the treated gr oup and the control group, 30 in each group. They were treated with XYA and Salb utamol aerosol (SA) respectively by spray inhalation once a day for seven days a s one therapeutic course to observe the antiasthmatic effect of the treatment. Changes of lung function and the levels of tumor necrosis factor α (TNF-α) , interleukine-2 receptor (IL-2R) and interleukine-8 (IL-8) in serum and sputum were observed before and after treatment using enzyme linked immunos orbent assay (ELISA). Levels of TNF-α, IL-2R andIL-8 in the sputum of part of the patients in the treatment group were also observed.Results: In the treated group, 6 patients had the asthma clinica lly controlled after treatment, 12 were markedly alleviated, 9 alleviated and 3 remained unchanged, while in the control group, the respective numbers were 4, 6 , 15 and 5. The controlled-markedly effective rate of XYA was 60.0%, which wa s significantly better than that of SA (33.3%, P <0.05). The one second forc ed expiratory volume percent (FEV1%) and peek expiratory flow rate (PEFR) improv ed significantly and the levels of TNF-α, IL-2R and IL-8 in serum decr eased noticeably in both groups after treatment ( P <0.05 or P <0.01), but the improvement in the treated group was more significant as compared with tho se in the control group ( P <0.05). The levels of TNF-α, IL-2R and IL -8 in sputum considerably lowered also after XYA treatment ( P <0.01).Conclusion: XYA could regulate the related cytokines in patient s with mild or moderate bronchial asthma, and reduce the releasing of inflammato ry factors, which is consistent with the improvement of lung functions, so as to ease the airway inflammation chiefly exhibited as cell infiltration in bron chi.

Composition of carbohydrates, surfactants, major elements and anions in PM2.5 during the 2013 Southeast Asia high pollution episode in Malaysia

Haze episodes have become a major concern in Malaysia over the past few decades and have an increasingly important impact on the country each and every year. During haze episodes from biomass burning in Southeast Asia, particularly from Sumatra, Indonesia, particulate matter PM2.5 is found to be one of the dangerous sources of airborne pollution and is known to seriously affect human health. This study determines the composition of carbohydrates （as levoglucosan）, surfactants, major elements, and anions in PM2.5 during a 2013 haze episode. PM2.5 samples were collected from Universiti Kebangsaan Malaysia, Bangi, using a high volume sampler during a seven-day monitoring campaign during the peak of that year＇s haze episode. PM2.5 concentrations ranged between 14.52 and 160.93 μg/m3, exceeding the 2005 WHO air quality guidelines for PM2.5 （25 μg/m3 for 24-h mean）. The patterns for levoglucosan, surfactants, major elements, and anionic compositions were proportional to the PM2.5 concentrations. Changes in PM2.5 observed on days 3 and 4 were influenced by a combination of meteorological factors, which substantiate the theory that such factors play a pivotal role in haze episodes.

Spatiotemporal trends of PM_(2.5) and its major chemical components at urban sites in Canada

To evaluate the effectiveness of emission control regulations designed for reducing air pollution, chemically resolved PM_(2.5) data have been collected across Canada through the National Air Pollution Surveillance network in the past decade. 24-hr time integrated PM_(2.5) collected at seven urban and two rural sites during 2010-2016 were analyzed to characterize geographical and seasonal patterns and associated potential causes. Site-specific seven-year mean gravimetric PM_(2.5) mass concentrations ranged from 5.7 to 9.6 μg/m^(3). Seven-year mean concentrations of SO_(4)^(2-), NO_(3)^(-), NH_(4)^(+), organic carbon(OC), and elemental carbon(EC) were in the range of 0.68 to 1.6, 0.21 to 1.5, 0.27 to 0.71, 1.1 to 1.9, and 0.37 to 0.71 μg/m^(3), accounting for 10.8%-18.1%, 3.7%-16.7%, 4.7%-7.4%, 18.4%-21.0%, and 6.4%-10.6%, respectively, of gravimetric PM_(2.5) mass. PM_(2.5) and its five major chemical components showed higher concentrations in southeastern Canada and lower values in Atlantic Canada, with the seven-year mean ratios between the two regions being on the order of 1.7 for PM_(2.5) and 1.8-7.1 for its chemical components. When comparing the concentrations between urban and rural sites within the same region, those of SO_(4)^(2-) and NH_(4)^(+) were comparable, while those of NO_(3)^(-), OC, and EC were around 20%, 40%-50%, and 70%-80%, respectively, higher at urban than rural sites, indicating the regional scale impacts of SO_(4)^(2-) and NH_(4)^(+) and effects of local sources on OC and EC. Monthly variations generally showed summertime peaks for SO_(4)^(2-) and wintertime peaks for NO_(3)^(-), but those of NH_(4)^(+), OC, and EC exhibited different seasonality at different locations.

Haze insights and mitigation in China: An overview

The present article provides an overview of the chemical and physical features of haze in China, focusing on the relationship between haze and atmospheric fine particles, and the formation mechanism of haze. It also summarizes several of control technologies and strategies to mitigate the occurrence of haze. The development of instruments and the analysis of measurements of ambient particles and precursor concentrations have provided important information about haze formation. Indeed, the use of new instruments has greatly facilitated current haze research in China. Examples of insightful results include the relationship between fine particles and haze, the chemical compositions and sources of particles, the impacts of the aging process on haze formation, and the application of technologies that control the formation of haze. Based on these results, two relevant issues need to be addressed： understanding the relationship between haze and fine particles and understanding how to control PM2.5.

Particulate matter characterization in a steelworks using conventional sampling and innovative lidar observations

Particulate matter （PM） emissions from steelworks cause public concern. Although end-of-pipe and pro- cess integrated measures have led to a significant drop in emissions of large particles from stacks, fine aerosols were not specifically considered, nor were emissions from fugitive and open sources. In this study, we deployed aerosol samplers together with a scanning ultra-violet （UV） lidar to characterize total suspended particles （TSP）, PM10, and PM2.5, in emissions from a large integrated steelworks in Spain over a 16-day period. We determined the content of carbonaceous, soluble inorganic, mineral dust, and metal species. A positive matrix factorization was carried out on our dataset. Despite mineral dust being predominant in all size fractions, the steelworks was clearly a source of carbonaceous species, resulting in production of secondary inorganic aerosols. In particular, stack emissions were a major contributor of fine particles, while open sources dominated the emissions of TSP, yielding up to 80% of particles larger than PM10. UV lidar provided 2D maps of aerosols in real time, with an ability to detect PM emissions and to visualize complex plumes. We suggest that air quality management of steelworks needs to focus on controlling large and coarse oarticle emissions, esoeciallv those from onen sources.