Publications by authors named "Fengkui Duan"

27 Publications

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Surface-enhanced Raman scattering for mixing state characterization of individual fine particles during a haze episode in Beijing, China.

J Environ Sci (China) 2021 Jun 22;104:216-224. Epub 2020 Dec 22.

MOE Key Laboratory of Resources and Environmental System Optimization, College of Environmental Science and Engineering, North China Electric Power University, Beijing 102206, China; Guangdong Provincial Key Laboratory of Petrochemcial Pollution Processes and Control, School of Environmental Science and Engineering, Guangdong University of Petrochemical Technology, Maoming 525000, China.

The nondestructive characterization of the mixing state of individual fine particles using the traditional single particle analysis technique remains a challenge. In this study, fine particles were collected during haze events under different pollution levels from September 5 to 11 2017 in Beijing, China. A nondestructive surface-enhanced Raman scattering (SERS) technique was employed to investigate the morphology, chemical composition, and mixing state of the multiple components in the individual fine particles. Optical image and SERS spectral analysis results show that soot existing in the form of opaque material was predominant during clear periods (PM ≤ 75 µg/m). During polluted periods (PM > 75 µg/m), opaque particles mixed with transparent particles (nitrates and sulfates) were generally observed. Direct classical least squares analysis further identified the relative abundances of the three major components of the single particles: soot (69.18%), nitrates (28.71%), and sulfates (2.11%). A negative correlation was observed between the abundance of soot and the mass concentration of PM. Furthermore, mapping analysis revealed that on hazy days, PM existed as a core-shell structure with soot surrounded by nitrates and sulfates. This mixing state analysis method for individual PM particles provides information regarding chemical composition and haze formation mechanisms, and has the potential to facilitate the formulation of haze prevention and control policies.
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http://dx.doi.org/10.1016/j.jes.2020.12.008DOI Listing
June 2021

Stronger secondary pollution processes despite decrease in gaseous precursors: A comparative analysis of summer 2020 and 2019 in Beijing.

Environ Pollut 2021 Jun 10;279:116923. Epub 2021 Mar 10.

State Key Joint Laboratory of Environment Simulation and Pollution Control, School of Environment, State Environmental Protection Key Laboratory of Sources and Control of Air Pollution Complex, Beijing Key Laboratory of Indoor Air Quality Evaluation and Control, Tsinghua University, Beijing, 100084, China.

To control the spread of COVID-19, China implemented a series of lockdowns, limiting various offline interactions. This provided an opportunity to study the response of air quality to emissions control. By comparing the characteristics of pollution in the summers of 2019 and 2020, we found a significant decrease in gaseous pollutants in 2020. However, particle pollution in the summer of 2020 was more severe; PM levels increased from 35.8 to 44.7 μg m, and PM increased from 51.4 to 69.0 μg m from 2019 to 2020. The higher PM was caused by two sandstorm events on May 11 and June 3, 2020, while the higher PM was the result of enhanced secondary formation processes indicated by the higher sulfate oxidation rate (SOR) and nitrate oxidation rate (NOR) in 2020. Higher SOR and NOR were attributed mainly to higher relative humidity and stronger oxidizing capacity. Analysis of PM distribution showed that severe haze occurred when particles within Bin2 (size ranging 1-2.5 μm) dominated. SO and SO remained stable under different periods at 0.5 and 0.8, respectively, indicating that SO existed mainly in smaller particles. Decreases in NO and increases in NO from clean to polluted conditions, similar to the variations in PM distribution, suggest that NO played a role in the worsening of pollution. O concentrations were higher in 2020 (108.6 μg m) than in 2019 (96.8 μg m). Marked decreases in fresh NO alleviated the titration of O. Furthermore, the oxidation reaction of NO that produces NO was dominant over the photochemical reaction of NO that produces O, making NO less important for O pollution. In comparison, a lower VOC/NO ratio (less than 10) meant that Beijing is a VOC-limited area; this indicates that in order to alleviate O pollution in Beijing, emissions of VOCs should be controlled.
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http://dx.doi.org/10.1016/j.envpol.2021.116923DOI Listing
June 2021

Characteristics and seasonal variations of high-molecular-weight oligomers in urban haze aerosols.

Sci Total Environ 2020 Dec 23;746:141209. Epub 2020 Jul 23.

State Key Joint Laboratory of Environment Simulation and Pollution Control, School of Environment, State Environmental Protection Key Laboratory of Sources and Control of Air Pollution Complex, Beijing Key Laboratory of Indoor Air Quality Evaluation and Control, Tsinghua University, Beijing 100084, China. Electronic address:

Organic aerosols (OA) undergo sophisticated physiochemical processes in the atmosphere, playing a crucial role in extreme haze formations over the Northern China Plain. However, current understandings of the detailed composition and formation pathways are limited. In this study, high-molecular weight (HMW) species were observed in samples collected year-round in urban Beijing, especially in autumn and winter, during 2016-2017. The positive-ion-mode mass spectra of matrix-assisted laser desorption ionization time-of-flight mass spectrometry (MALDI-TOF-MS) showed that higher signal intensities were obtained in the mass-to-charge (m/z) ranges of 200-500 and 800-900, with repetitive mass difference patterns of m/z 12, 14, 16, and 18. This provided sound evidence that high-molecular-weight oligomers were generated as haze episodes became exacerbated. These oligomer signal intensities were enhanced in the presence of high relative humidity, aerosol water content, and PM (particles with an aerodynamic diameter ≤ 2.5 μm) mass, proving that the multiphase reaction processes play a fundamental role in haze formation in Beijing. Our study can form a basis for improved air pollution mitigation measures aimed at OA to improve health outcomes.
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http://dx.doi.org/10.1016/j.scitotenv.2020.141209DOI Listing
December 2020

Mixed and intensive haze pollution during the transition period between autumn and winter in Beijing, China.

Sci Total Environ 2020 Apr 31;711:134745. Epub 2019 Oct 31.

State Key Joint Laboratory of Environment Simulation and Pollution Control, School of Environment, State Environmental Protection Key Laboratory of Sources and Control of Air Pollution Complex, Beijing Key Laboratory of Indoor Air Quality Evaluation and Control, Tsinghua University, Beijing 100084, China.

In the Northern China Plain (NCP), extreme haze events with high concentrations of fine particles occur frequently during the winter but rarely occur in autumn. In this study, we present a synthetic analysis of particulate constituents during the historically polluted transition period of autumn-winter in 2018, revealing that mixed-type haze episodes are the result of regional transport, homogeneous/heterogeneous conversion, and sandstorm influences. The hydrolysis process of NO at higher relative humidity levels (>70%), which feature an enhanced nitrate oxidation ratio (0.30-0.70) and NO concentration (>60 μg m), was the driving factor for high PM mass concentrations during the observation periods. The long-distance transport of sandstorms, characterized by decreasing PM/PM ratios (<30%) from the north/northwest, is the most important factor for the explosive growth of PM concentration. These results can help us gain a comprehensive understanding of haze formation and highlight the importance of nitrate chemistry in the aqueous phase. The results suggest that persistent NO emission reduction measures must be made to better achieve air quality standards in Beijing and the NCP region.
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http://dx.doi.org/10.1016/j.scitotenv.2019.134745DOI Listing
April 2020

Characteristics and formation mechanisms of winter haze in Changzhou, a highly polluted industrial city in the Yangtze River Delta, China.

Environ Pollut 2019 Oct 8;253:377-383. Epub 2019 Jul 8.

Kimoto Electric Co. Ltd, Funahashi-Cho, Tennouji-Ku, Osaka 543-0024, Japan.

Changzhou, an industrial city in the Yangtze River Delta, has been experiencing serious haze pollution, particularly in winter. However, studies pertaining to the haze in Changzhou are very limited, which makes it difficult to understand the characteristics and formation of winter haze in this area, and develop effective control measures. In this study, we carried out continuous online observation of particulate matter, chemical components, and meteorology in Changzhou in February 2017. Our results showed that haze pollution occurred frequently in Changzhou winter and exhibited two patterns: dry haze with low relative humidity (RH) and wet haze with high RH. Water-soluble inorganic ions (SO, NO, and NH) accounted for ∼52.2% of the PM mass, of which sulfate was dominant in wet haze periods while nitrate was dominant in other periods. With the deterioration of haze pollution, the proportion of nitrate in PM increased, while sulfate proportion increased under wet haze and decreased under dry haze. Dry haze and wet haze appeared under slow north wind and south wind, respectively, and strong north wind or sea breeze scavenged pollution. We found that formation of nitrate occurred rapidly in daytime with high concentrations of odd oxygen (O = O + NO), whereas formation of sulfate occurred rapidly during nighttime with high RH, indicating that photochemistry and heterogeneous reaction were the major formation mechanisms for nitrate and sulfate, respectively. Through the cluster analysis of 36-h backward trajectories, five sources of air masses from three directions were identified. High PM concentrations (84.1 μg m on average) usually occurred under the influence of two clusters (46%) from the northwest, indicating that regional transport from northern China aggravated the winter haze pollution in Changzhou. Emission reduction, particularly the mobile sources, and regional joint prevention and control can help to mitigate the winter haze in Changzhou.
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http://dx.doi.org/10.1016/j.envpol.2019.07.011DOI Listing
October 2019

Air pollution characteristics and their relationship with emissions and meteorology in the Yangtze River Delta region during 2014-2016.

J Environ Sci (China) 2019 Sep 12;83:8-20. Epub 2019 Mar 12.

State Key Joint Laboratory of Environment Simulation and Pollution Control, School of Environment, State Environmental Protection Key Laboratory of Sources and Control of Air Pollution Complex, Beijing Key Laboratory of Indoor Air Quality Evaluation and Control, Tsinghua University, Beijing 100084, China.

With rapid economic growth and urbanization, the Yangtze River Delta (YRD) region in China has experienced serious air pollution challenges. In this study, we analyzed the air pollution characteristics and their relationship with emissions and meteorology in the YRD region during 2014-2016. In recent years, the concentrations of all air pollutants, except O, decreased. Spatially, the PM, PM, SO, and CO concentrations were higher in the northern YRD region, and NO and O were higher in the central YRD region. Based on the number of non-attainment days (i.e., days with air quality index greater than 100), PM was the largest contributor to air pollution in the YRD region, followed by O, PM, and NO. However, particulate matter pollution has declined gradually, while O pollution worsened. Meteorological conditions mainly influenced day-to-day variations in pollutant concentrations. PM concentration was inversely related to wind speed, while O concentration was positively correlated with temperature and negatively correlated with relative humidity. The air quality improvement in recent years was mainly attributed to emission reductions. During 2014-2016, PM, PM, SO, NO, CO, NH, and volatile organic compound (VOC) emissions in the YRD region were reduced by 26.3%, 29.2%, 32.4%, 8.1%, 15.9%, 4.5%, and 0.3%, respectively. Regional transport also contributed to the air pollution. During regional haze periods, pollutants from North China and East China aggravated the pollution in the YRD region. Our findings suggest that emission reduction and regional joint prevention and control helped to improve the air quality in the YRD region.
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http://dx.doi.org/10.1016/j.jes.2019.02.031DOI Listing
September 2019

Parameterization of heterogeneous reaction of SO to sulfate on dust with coexistence of NH and NO under different humidity conditions.

Atmos Environ (1994) 2019 Jul;208:133-140

State Key Joint Laboratory of Environment Simulation and Pollution Control, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing, 100085, China.

Sulfate plays an important role in atmospheric haze in China, which has received considerable attention in recent years. Various types of parameterization methods and heterogeneous oxidation rates of SO have been used in previous studies. However, properly representing heterogeneous sulfate formation in air quality models remains a big challenge. In this study, we quantified the heterogeneous oxidation reaction using experimental results that approximate the haze conditions in China. Firstly, a series of experiments were conducted to investigate the heterogeneous uptake of SO with different relative humidity (RH) levels and the presence of NH and NO on natural dust surfaces. Then the uptake coefficients for heterogeneous oxidation of SO to sulfate at different RH under NH and NOcoexistence were parameterized based on the experimental results and implemented in the Community Multiscale Air Quality modeling system (CMAQ). Simulation results suggested that this new parameterization improved model performance by 6.6% in the simulation of wintertime sulfate concentrations for Beijing. The simulated maximum growth rate of SO during a heavy pollution period increased from 0.97 μg m h to 10.11 μg m h. The heterogeneous oxidation of SO in the presence of NH contributed up to 23% of the sulfate concentration during heavy pollution periods.
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http://dx.doi.org/10.1016/j.atmosenv.2019.04.004DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6559380PMC
July 2019

Biotoxicity of water-soluble species in PM using Chlorella.

Environ Pollut 2019 Jul 8;250:914-921. Epub 2019 Apr 8.

State Key Joint Laboratory of Environment Simulation and Pollution Control, School of Environment, State Environmental Protection Key Laboratory of Sources and Control of Air Pollution Complex, Beijing Key Laboratory of Indoor Air Quality Evaluation and Control, Tsinghua University, Beijing, 100084, China.

China has been faced with severe haze pollution, which is hazardous to human health. Among the air pollutants, PM (particles with an aerodynamic diameter ≤ 2.5 μm) is the most dangerous because of its toxicity and impact on human health and ecosystems. However, there has been limited research on PM particle toxicity. In the present study, we collected daily PM samples from January 1 to March 31, 2018 and selected samples to extract water-soluble species, including SO, NO, WSOC, and NH. These samples represented clean, good, slight, moderate, and heavy pollution days. After extraction using an ultrasonic method, PM solutions were obtained. We used Chlorella as the test algae and studied the content of chlorophyll a, as well as the variation in fluorescence when they were placed into the PM extraction solution, and their submicroscopic structure was analyzed using transmission electron microscopy (TEM). The results showed that when the air quality was relatively clean and good (PM concentration ≤ 75 μg m), the PM extraction solutions had no inhibiting effects on Chlorella, whereas when the air quality was polluted (PM concentration > 75 μg m) and heavily polluted (PM concentration > 150 μg m), with increasing PM concentrations and exposure time, the chlorophyll a content in Chlorella decreased. Moreover, the maximum photochemical quantum yield (F/F) of Chlorella obviously decreased, indicating chlorophyll inhibition during polluted days with increasing PM concentrations. The effects on the chlorophyll fluorescence parameters were also obvious, leading to an increase of energy dissipated per unit reaction center (DI/RC), suggesting that Chlorella could survive when exposed to PM solutions, whereas the physiological activities were significantly inhibited. The TEM analysis showed that there were few effects on Chlorella cell microstructure during clean days, whereas plasmolysis occurred during light- and medium-polluted days. With increasing pollution levels, plasmolysis became more and more apparent, until the organelles inside the cells were thoroughly destroyed and most of the parts could not be recognized.
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http://dx.doi.org/10.1016/j.envpol.2019.04.017DOI Listing
July 2019

Physicochemical analysis of individual atmospheric fine particles based on effective surface-enhanced Raman spectroscopy.

J Environ Sci (China) 2019 Jan 19;75:388-395. Epub 2018 Jun 19.

State Key Joint Laboratory of Environment Simulation and Pollution Control, School of Environment, Tsinghua University, Beijing 100084, China.

Fine particles associated with haze pollution threaten the health of more than 400 million people in China. It is therefore of great importance to thoroughly investigate and understand their composition. To determine the physicochemical properties in atmospheric fine particles at the micrometer level, we described a sensitive and feasible surface-enhanced Raman scattering (SERS) method using Ag foil as a substrate. This novel method enhanced the Raman signal intensities up to 10,000 a.u. for ν(NO) in fine particles. The SERS effect of Ag foil was further studied experimentally and theoretically and found to have an enhancement factor of the order of ~10. Size-fractionated real particle samples with aerodynamic diameters of 0.4-2.5 μm were successfully collected on a heavy haze day, allowing ready observation of morphology and identification of chemical components, such as soot, nitrates, and sulfates. These results suggest that the Ag-foil-based SERS technique can be effectively used to determine the microscopic characteristics of individual fine particles, which will help to understand haze formation mechanisms and formulate governance policies.
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http://dx.doi.org/10.1016/j.jes.2018.06.006DOI Listing
January 2019

Haze formation indicator based on observation of critical carbonaceous species in the atmosphere.

Environ Pollut 2019 Jan 4;244:84-92. Epub 2018 Oct 4.

Kimoto Electric Co. Ltd, Funahashi-Cho, Tennouji-Ku, Osaka, 543-0024, Japan.

Organic aerosol (OA) are always the most abundant species in terms of relative proportion to PM concentration in Beijing, while in previous studies, poor link between carbonaceous particles and their gaseous precursors were established based on field observation results. Through this study, we provided a comprehensive analysis of critical carbonaceous species in the atmosphere. The concentrations, diurnal variations, conversions, and gas-particle partitioning (F-factor) of 8 carbonaceous species, carbon dioxide (CO), carbon monoxide (CO), methane (CH), volatile organic compounds (VOCs), non-methane hydrocarbon (NMHC), organic carbon (OC), elemental carbon (EC), and water soluble organic compounds (WSOCs), in Beijing were analyzed synthetically. Carbonaceous gases (CO, CO, VOCs, and CH) and OC/EC ratios exhibited double-peak diurnal patterns with a pronounced midnight peak, especially in winter. High correlation between VOCs and OC during winter nighttime indicated that OC was formed from VOCs precursors via an unknown mechanism at relative humidity greater than 50% and 80%, thereby promoting WSOC formation in PM and PM respectively. The established F-factor method was effective to describe gas-to-particle transformation of carbonaceous species and was a good indicator for haze events since high F-factors corresponded with enhanced PM level. Moreover, higher F-factors in winter indicated carbonaceous species were more likely to exist as particles in Beijing. These results can help gain a comprehensive understanding of carbon cycle and formation of secondary organic aerosols from gaseous precursors in the atmosphere.
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http://dx.doi.org/10.1016/j.envpol.2018.10.006DOI Listing
January 2019

Sulfate-nitrate-ammonium as double salts in PM: Direct observations and implications for haze events.

Sci Total Environ 2019 Jan 3;647:204-209. Epub 2018 Aug 3.

State Key Joint Laboratory of Environmental Simulation and Pollution Control, School of Environment, Tsinghua University, Beijing 100084, China.

Obtaining detailed information on sulfate-nitrate-ammonium (SNA) is fundamentally important to explain the formation of haze in China, since it is a dominant component of fine particulate matter (PM) and plays a critical role in the deterioration of air quality. Several single-particle analysis methods have been applied to study and explain SNA formation; however, determining its mixture state remains a challenge. This study describes a direct observation of the SNA components in atmospheric particles on a single-particle scale, and details the first use of a non-destructive surface-enhanced Raman scattering (SERS) technique for SNA analysis. We studied PM collected at a site on the premises of Tsinghua University in Beijing, China, during a winter haze episode (12.15.2016-12.23.2016). The on-line data show that the SNA component accounted for 9.4% to 68.2% of the total mass of PM, becoming dominant on heavy haze days, and the sulfate concentration increased with the nitrate concentration (R = 0.72). Furthermore, the off-line SERS and scanning electron microscopy-energy dispersive X ray analysis (SEM-EDS) results for the single particles collected also indicated that SNA increase with increasing haze pollution. The existing state of the SNA component on each haze day was observed directly in a non-destructive manner mainly in the form of double salts such as 3(NHNO)·(NH)SO and 2(NHNO)·(NH)SO. A Raman mapping experiment further confirmed that the SNA was internally mixed. Our data also show that SNA can evaporate under high-vacuum scanning electron microscopy conditions, suggesting that SERS is an effective method to directly observe SNA without sample loss and may represent a promising single-particle technique to supplement traditional electron microscopy methods. This work will provide evidence for the SNA formation, particularly during haze events.
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http://dx.doi.org/10.1016/j.scitotenv.2018.07.107DOI Listing
January 2019

Case study of spring haze in Beijing: Characteristics, formation processes, secondary transition, and regional transportation.

Environ Pollut 2018 Nov 6;242(Pt A):544-554. Epub 2018 Jul 6.

Kimoto Electric Co. Ltd, Funahashi-Cho, Tennouji-Ku Osaka 543-0024, Japan.

Continuous haze monitoring was conducted from 12:00 3 April to 12:00 8 April 2016 in Beijing, China to develop a more detailed understanding of spring haze characteristics. The PM concentration ranged from 6.30 to 165 μg m with an average of 63.8 μg m. Nitrate was the most abundant species, accounting for 36.4% of PM, followed by organic carbon (21.5%), NH (19.3%), SO (18.8%), and elemental carbon (4.10%), indicating the key role of nitrate in this haze event. Species contribution varied based on the phase of the haze event. For example, sulfate concentration was high during the haze formation phase, nitrate was high during the haze, and secondary organic carbon (SOC) had the highest contribution during the scavenging phase. The secondary transition of sulfate was influenced by SO, followed by relative humidity (RH) and O (O+NO). Nitrate formation occurred in two stages: through NO oxidation, which was vulnerable to O; and by the partitioning of N (+5) which was susceptible to RH and temperature. SOC tended to form when O and RH were balanced. According to hourly species behavior, sulfate and nitrate were enriched during haze formation when the mixed layer height decreased. However, SOC accumulated prior to the haze event and during formation, which demonstrated the strong contribution of secondary inorganic aerosols, and the limiting contribution of SOC to this haze case. Investigating backward trajectories showed that high speed northwestern air masses following a straight path corresponded to the clear periods, while southwesterly air masses which traversed heavily polluted regions brought abundant pollutants to Beijing and stimulated the occurrence of haze pollution. Results indicate that the control of NO needs to be addressed to reduce spring haze. Finally, the correlation between air mass trajectories and pollution conditions in Beijing reinforce the necessity of inter-regional cooperation and control.
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http://dx.doi.org/10.1016/j.envpol.2018.07.001DOI Listing
November 2018

Typical winter haze pollution in Zibo, an industrial city in China: Characteristics, secondary formation, and regional contribution.

Environ Pollut 2017 Oct 10;229:339-349. Epub 2017 Jun 10.

School of Resources and Environmental Engineering, Shandong University of Technology, Zibo 255049, Shandong Province, China.

Heavy haze pollution occurs frequently in northern China, most critically in the Beijing-Tianjin-Hebei area (BTH). Zibo, an industrial city located in Shandong province, is often listed as one of the top ten most polluted cities in China, particularly in winter. However, no studies of haze in Zibo have been conducted, which limits the understanding of the source and formation of haze pollution in this area, as well as mutual effects with the BTH area. We carried out online and continuous integrated field observation of particulate matter in winter, from 11 to 25 January 2015. SO, NO, and NH (SIA) and organics were the main constituents of PM, contributing 59.4% and 33.6%, respectively. With the increasing severity of pollution, the contribution of SIA increased while that of organics decreased. Meteorological conditions play an important role in haze formation; high relative humidity (RH) and low wind speed increased both the accumulation of pollutants and the secondary transition from gas precursors (gas-particle phase partitioning). Since RH and the presence of O can indicate heterogeneous and photochemistry processes, respectively, we carried out correlation analysis and linear regression to identify their relative importance to the three main secondary species (sulfate, nitrate, and secondary organic carbon (SOC)). We found that the impact of RH is in the order of SO > NO > SOC, while the impact of O is reversed, in the order of SOC > NO > SO, indicating different effect of these factors on the secondary formation of main species in winter. Cluster analysis of backward trajectories showed that, during the observation period, six directional sources of air masses were identified, and more than 90% came from highly industrialized areas, indicating that regional transport from industrialized areas aggravates the haze pollution in Zibo. Inter-regional joint prevention and control is necessary to prevent further deterioration of the air quality.
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http://dx.doi.org/10.1016/j.envpol.2017.05.081DOI Listing
October 2017

Characteristics of the secondary water-soluble ions in a typical autumn haze in Beijing.

Environ Pollut 2017 Aug 3;227:296-305. Epub 2017 May 3.

College of Resources and Environmental Sciences, China Agricultural University, Beijing 100094, China.

Four haze episodes (EPs) were observed in October 2014 in Beijing, China. For better understanding of the characteristics and the formation mechanisms of PM (particulate matter with an aerodynamic diameter ≤ 2.5 μm), especially secondary water-soluble inorganic species in these haze events, hourly concentrations of PM, sulfate, nitrate, and ammonium (SNA) were measured in this study. Concentrations of gaseous pollutants and meteorological parameters were also measured. The average concentration of PM was 106.6 ± 83.5 μg m, which accounted for around 53% of PM (particulate matter with an aerodynamic diameter ≤ 10 μm) mass. Nitrogen dioxide (NO) concentration was much higher than that of sulfur dioxide (SO) since October is a non-heating month. SNA is the most abundant secondary water-soluble inorganic species and contributed to 33% of PM mass concentration. Sulfur oxidation ratio (SOR) was much higher than nitrogen oxidation ratio (NOR). NOR and SOR increased with elevated PM levels and heterogeneous processes seemed to be the most plausible explanation of this increase. Relative humidity (RH), which is of great influence on aerosol liquid water content (ALWC), played a considerable role in the formation of secondary inorganic aerosols, accelerated the secondary transformation of gaseous precursors, and further aggravated haze pollution. The positive feedback loop associated with high aerosol levels and low planetary boundary layer (PBL) height led to the evolution and exacerbation of heavy haze pollution. Fire maps and 48-h air mass backward trajectories supported the significant impact of biomass burning activities and regional transport on haze formation over Beijing in October 2014.
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http://dx.doi.org/10.1016/j.envpol.2017.04.076DOI Listing
August 2017

The "Parade Blue": effects of short-term emission control on aerosol chemistry.

Faraday Discuss 2016 07;189:317-35

State Key Joint Laboratory of Environment Simulation and Pollution Control, School of Environment, Tsinghua University, Beijing 100084, China and Collaborative Innovation Center for Regional Environmental Quality, Beijing 100084, China and State Environmental Protection Key Laboratory of Sources and Control of Air Pollution Complex, Tsinghua University, Beijing 100084, China.

The strict control on emissions implemented in Beijing, China, during the 2015 China Victory Day Parade (V-day Parade) to commemorate the 70(th) Anniversary of Victory in World War II, provided a good opportunity to investigate the relationship between emission sources and aerosol chemistry in a heavily polluted megacity. From August 11 to September 3, 2015, an Aerosol Chemical Speciation Monitor was deployed in urban Beijing, together with other collocated instruments, for the real-time measurement of submicron aerosol characteristics. The average PM1 mass concentration was 11.3 (±6.7) μg m(-3) during the V-day Parade, 63.5% lower than that before the V-day Parade. Differently to the relatively smaller decrease of organics (53%), secondary inorganic aerosols (sulfate, nitrate and ammonium) showed significant reductions of 65-78% during the V-day Parade. According to the positive matrix factorization results, primary organic aerosol (POA) from traffic and cooking emissions decreased by 41.5% during the parade, whereas secondary organic aerosol (SOA) presented a much greater reduction (59%). The net effectiveness of emission control measures was investigated further under comparable weather conditions before and during the parade. By excluding the effects of meteorological parameters, the total PM1 mass was reduced by 52-57% because of the emission controls. Although the mass concentrations of aerosol species were reduced substantially, the PM1 bulk composition was similar before and during the control period as a consequence of synergetic control of various precursors. The emission restrictions also suppressed the secondary formation processes of sulfate and nitrate, indicated by the substantially reduced SOR and NOR (molar ratios of sulfate or nitrate to the sums of the sulfate and SO2 or nitrate and NO2) during the event. The study also explored the influence of emission controls on the evolution of organic aerosol using the mass ratios of SOA/POA and oxygen-to-carbon ratios. The results showed that for northwesterly airflows, emission restrictions during the V-day Parade also reduced the oxidation degree of organic aerosol.
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http://dx.doi.org/10.1039/c6fd00004eDOI Listing
July 2016

Episode-Based Evolution Pattern Analysis of Haze Pollution: Method Development and Results from Beijing, China.

Environ Sci Technol 2016 May 15;50(9):4632-41. Epub 2016 Apr 15.

State Environmental Protection Key Laboratory of Sources and Control of Air Pollution Complex, Beijing 100084, China.

Haze episodes occurred in Beijing repeatedly in 2013, resulting in 189 polluted days. These episodes differed in terms of sources, formation processes, and chemical composition and thus required different control policies. Therefore, an overview of the similarities and differences among these episodes is needed. For this purpose, we conducted one-year online observations and developed a program that can simultaneously divide haze episodes and identify their shapes. A total of 73 episodes were identified, and their shapes were linked with synoptic conditions. Pure-haze events dominated in wintertime, whereas mixed haze-dust (PM2.5/PM10 < 60%) and mixed haze-fog (Aerosol Water/PM2.5 ∼ 0.3) events dominated in spring and summer-autumn, respectively. For all types, increase of ratio of PM2.5 in PM10 was typically achieved before PM2.5 reached ∼150 μg/m(3). In all PM2.5 species observed, organic matter (OM) was always the most abundant component (18-60%), but it was rarely the driving factor: its relative contribution usually decreased as the pollution level increased. The only OM-driven episode observed was associated with intensive biomass-burning activities. In comparison, haze evolution generally coincided with increasing sulfur and nitrogen oxidation ratios (SOR and NOR), indicating the enhanced production of secondary inorganic species. Applicability of these conclusions required further tests with simultaneously multisite observations.
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http://dx.doi.org/10.1021/acs.est.5b05593DOI Listing
May 2016

Fine particulate matter induces vascular endothelial activation IL-6 dependent JAK1/STAT3 signaling pathway.

Toxicol Res (Camb) 2016 May 4;5(3):946-953. Epub 2016 Apr 4.

Department of Toxicology and Sanitary Chemistry , School of Public Health , Capital Medical University , Beijing 100069 , P.R. China . Email: ; Email: ; ; Tel: +86 010 83911868, +86 010 83911507.

Exposure to PM2.5 has been strongly linked to endothelial dysfunction. However, the underlying mechanism of PM2.5 on the vascular endothelial function is poorly understood. This study examined the toxic effect and underlying mechanism of PM2.5 on human umbilical vein endothelial cells (HUVECs). Decreased cell viability and increased LDH activity were observed in the PM2.5-treated HUVECs in a dose-dependent manner. The production of ROS, MDA, and the inhibition of SOD activity were also triggered by PM2.5 in HUVECs. In addition, PM2.5 increased the intracellular levels of proinflammatory cytokines (IL-6, TNF-a, IL-1β, IL-8 and CRP), cell adhesion molecules (ICAM-1, VCAM-1) and tissue factor (TF), resulted in endothelial activation. For an in-depth study, the protein levels of IL-6, JAK1 and STAT3 were up-regulated significantly, while the expression of JAK2 and SOCS1 were down-regulated gradually in PM2.5-treated HUVECs in a dose-dependent manner. These results show that PM2.5 triggered endothelial activation upregulation of the IL-6 dependent JAK1/STAT3 signaling pathway. This will provide new insights into the toxic effects and mechanisms of cardiovascular diseases triggered by ambient air pollution.
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http://dx.doi.org/10.1039/c5tx00351bDOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6062355PMC
May 2016

Seasonal variations and source estimation of saccharides in atmospheric particulate matter in Beijing, China.

Chemosphere 2016 May 26;150:365-377. Epub 2016 Feb 26.

State Key Joint Laboratory of Environment Simulation and Pollution Control, School of Environment, Tsinghua University, Beijing, China. Electronic address:

Saccharides are important constituents of atmospheric particulate matter (PM). In order to better understand the sources and seasonal variations of saccharides in aerosols in Beijing, China, saccharide composition was measured in ambient PM samples collected at an urban site in Beijing. The highest concentrations of total saccharides in Beijing were observed in autumn, while an episode with abnormal high total saccharide levels was observed from 15 to 23 June, 2011, due to extensive agricultural residue burning in northern China during the wheat harvest season. Compared to the other two categories of saccharides, sugars and sugar alcohols, anhydrosugars were the predominant saccharide group, indicating that biomass burning contributions to Beijing urban aerosol were significant. Ambient sugar and sugar alcohol levels in summer and autumn were higher than those in spring and winter, while they were more abundant in PM2.5 during winter time. Levoglucosan was the most abundant saccharide compound in both PM2.5 and PM10, the annual contributions of which to total measured saccharides in PM2.5 and PM10 were 61.5% and 54.1%, respectively. To further investigate the sources of the saccharides in ambient aerosols in Beijing, the PM10 datasets were subjected to positive matrix factorization (PMF) analysis. Based on the objective function to be minimized and the interpretable factors identified by PMF, six factors appeared to be optimal as to the probable origin of saccharides in the atmosphere in Beijing, including biomass burning, soil or dust, isoprene SOA and the direct release of airborne fungal spores and pollen.
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http://dx.doi.org/10.1016/j.chemosphere.2016.02.002DOI Listing
May 2016

Extreme Air Pollution Conditions Adversely Affect Blood Pressure and Insulin Resistance: The Air Pollution and Cardiometabolic Disease Study.

Hypertension 2016 Jan 16;67(1):77-85. Epub 2015 Nov 16.

From the Division of Cardiovascular Medicine (R.D.B.) and Department of Biostatistics (Z.S., B.M.), University of Michigan, Ann Arbor; Air Quality Research Division, Environment Canada, Toronto, Ontario, Canada (J.R.B.); Department of Cardiology, Peking Union Medical College Hospital, Beijing, China (X.Z., Y.R., J.Y., L.S., R.L., H.L., S.Z., Q.F., Z.F.); Division of Cardiovascular Medicine, University of Maryland, Baltimore (X.R., S.R.); Department of Environmental Science and Engineering, Tsinghua University, Beijing, China (F.D.); Cardiovascular Institute and Fuwai Hospital, Peking Union Medical College and Chinese Academy of Medical Sciences, Beijing, China (D.G.); and Davis Heart and Lung Research Institute, Ohio State University College of Medicine, Columbus (Q.S.).

Mounting evidence supports that fine particulate matter adversely affects cardiometabolic diseases particularly in susceptible individuals; however, health effects induced by the extreme concentrations within megacities in Asia are not well described. We enrolled 65 nonsmoking adults with metabolic syndrome and insulin resistance in the Beijing metropolitan area into a panel study of 4 repeated visits across 4 seasons since 2012. Daily ambient fine particulate matter and personal black carbon levels ranged from 9.0 to 552.5 µg/m(3) and 0.2 to 24.5 µg/m(3), respectively, with extreme levels observed during January 2013. Cumulative fine particulate matter exposure windows across the prior 1 to 7 days were significantly associated with systolic blood pressure elevations ranging from 2.0 (95% confidence interval, 0.3-3.7) to 2.7 (0.6-4.8) mm Hg per SD increase (67.2 µg/m(3)), whereas cumulative black carbon exposure during the previous 2 to 5 days were significantly associated with ranges in elevations in diastolic blood pressure from 1.3 (0.0-2.5) to 1.7 (0.3-3.2) mm Hg per SD increase (3.6 µg/m(3)). Both black carbon and fine particulate matter were significantly associated with worsening insulin resistance (0.18 [0.01-0.36] and 0.22 [0.04-0.39] unit increase per SD increase of personal-level black carbon and 0.18 [0.02-0.34] and 0.22 [0.08-0.36] unit increase per SD increase of ambient fine particulate matter on lag days 4 and 5). These results provide important global public health warnings that air pollution may pose a risk to cardiometabolic health even at the extremely high concentrations faced by billions of people in the developing world today.
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http://dx.doi.org/10.1161/HYPERTENSIONAHA.115.06237DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4830086PMC
January 2016

Transcriptomic Analyses of the Biological Effects of Airborne PM2.5 Exposure on Human Bronchial Epithelial Cells.

PLoS One 2015 18;10(9):e0138267. Epub 2015 Sep 18.

State Key Joint Laboratory of Environment Simulation and Pollution Control, School of Environment, Tsinghua University, Beijing, 100084, China.

Epidemiological studies have associated high levels of airborne particulate matter (PM) with increased respiratory diseases. In order to investigate the mechanisms of air pollution-induced lung toxicity in humans, human bronchial epithelial cells (16HBE) were exposed to various concentrations of particles smaller than 2.5 μm (PM2.5) collected from Beijing, China. After observing that PM2.5 decreased cell viability in a dose-dependent manner, we first used Illumina RNA-seq to identify genes and pathways that may contribute to PM2.5-induced toxicity to 16HBE cells. A total of 539 genes, 283 up-regulated and 256 down-regulated, were identified to be significantly differentially expressed after exposure to 25 μg/cm2 PM2.5. PM2.5 induced a large number of genes involved in responses to xenobtiotic stimuli, metabolic response, and inflammatory and immune response pathways such as MAPK signaling and cytokine-cytokine receptor interaction, which might contribute to PM2.5-related pulmonary diseases. We then confirmed our RNA-seq results by qPCR and by analysis of IL-6, CYP1A1, and IL-8 protein expression. Finally, ELISA assay demonstrated a significant association between exposure to PM2.5 and secretion of IL-6. This research provides a new insight into the mechanisms underlying PM2.5-induced respiratory diseases in Beijing.
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http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0138267PLOS
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4575100PMC
June 2016

Personal black carbon exposure influences ambulatory blood pressure: air pollution and cardiometabolic disease (AIRCMD-China) study.

Hypertension 2014 Apr 13;63(4):871-7. Epub 2014 Jan 13.

110 S Paca St, 7th Floor, Room 7-N-100, Baltimore, MD 21201, or Zhongjie Fan, No. 1 Shuaifuyuan, Dongcheng District, Beijing, China 100730, E-mail

Few prospective studies have assessed the blood pressure effect of extremely high air pollution encountered in Asia's megacities. The objective of this study was to evaluate the association between combustion-related air pollution with ambulatory blood pressure and autonomic function. During February to July 2012, personal black carbon was determined for 5 consecutive days using microaethalometers in patients with metabolic syndrome in Beijing, China. Simultaneous ambient fine particulate matter concentration was obtained from the Beijing Municipal Environmental Monitoring Center and the US Embassy. Twenty-four-hour ambulatory blood pressure and heart rate variability were measured from day 4. Arterial stiffness and endothelial function were obtained at the end of day 5. For statistical analysis, we used generalized additive mixed models for repeated outcomes and generalized linear models for single/summary outcomes. Mean (SD) of personal black carbon and fine particulate matter during 24 hours was 4.66 (2.89) and 64.2 (36.9) μg/m(3). Exposure to high levels of black carbon in the preceding hours was associated significantly with adverse cardiovascular responses. A unit increase in personal black carbon during the previous 10 hours was associated with an increase in systolic blood pressure of 0.53 mm Hg and diastolic blood pressure of 0.37 mm Hg (95% confidence interval, 0.17-0.89 and 0.10-0.65 mm Hg, respectively), a percentage change in low frequency to high frequency ratio of 5.11 and mean interbeat interval of -0.06 (95% confidence interval, 0.62-9.60 and -0.11 to -0.01, respectively). These findings highlight the public health effect of air pollution and the importance of reducing air pollution.
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http://dx.doi.org/10.1161/HYPERTENSIONAHA.113.02588DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4445364PMC
April 2014

Measurement of humic-like substances in aerosols: a review.

Environ Pollut 2013 Oct 5;181:301-14. Epub 2013 Jul 5.

State Key Joint Laboratory of Environment Simulation and Pollution Control, School of Environment, Tsinghua University, Beijing 100084, People's Republic of China.

Aerosol-phase humic-like substances (HULIS) have received increasingly attention due to their universal ambient presence, active participation in atmospheric chemistry and important environmental and health effects. In last decade, intensive field works have promoted development of quantification and analysis method, unearthed spatio-temporal variation, and proved evidence for source identification of HULIS. These important developments were summarized in this review to provide a global perspective of HULIS. The diverse operational HULIS definitions were gradually focused onto several versions. Although found globally in Europe, Asia, Australasia and North America, HULIS are far more typical in continental and near-ground aerosols. HULIS concentrations varied from <1 μg/m(3) to >13 μg/m(3), with their carbon fraction making up 9%-72% of water soluble organic carbon. Dominant HULIS source was suggested as secondary processes and biomass burning, with the detailed formation pathways suggested and verified in laboratory works.
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http://dx.doi.org/10.1016/j.envpol.2013.05.055DOI Listing
October 2013

Characteristics and source identification of fine particulate n-alkanes in Beijing, China.

J Environ Sci (China) 2010 ;22(7):998-1005

State Key Joint Laboratory of Environment Simulation and Pollution Control, Department of Environmental Science & Engineering, Tsinghua University, Beijing 100084, China.

Ambient particulate n-alkanes were determined for fine particle (PM2.5) samples collected from Sep 2003 to July 2004 in Beijing, China. The average concentration of total n-alkanes (sigma n-alkanes) from C11 to C34 was 425.72 ng/m3, ranged from 7.02 to 2893.28 ng/m3. The concentration distributions of n-alkanes homologues in this study exhibited peaks at C21 and C29 in heating season, and C29 in non-heating season. The average carbon preference index (CPI) value was 1.88 in the range of 1.18-3.88. The maximum CPI in summer indicated the contribution of biogenic origins such as plant wax; while the minimum CPI value in winter was probably a result of fossil fuel combustion. Preliminary estimation from these results showed that 59% of the n-alkanes in PM2.5 in Beijing summer originated from plant wax, while 74%-88% was from fossil fuel combustion in other three seasons. Source estimation was further performed using principal component analysis method. Two major components were yielded accounting for 57.3% and 30.9% of the total variance, which presented the fossil fuel and biogenic contribution, respectively.
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http://dx.doi.org/10.1016/s1001-0742(09)60210-2DOI Listing
January 2011

Chemical characteristics of PM2.5 during a typical haze episode in Guangzhou.

J Environ Sci (China) 2009 ;21(6):774-81

Department of Environmental Science and Engineering, Tsinghua University, Beijing 100084, China.

The chemical characteristics (water-soluble ions and carbonaceous species) of PM2.5 in Guangzhou were measured during a typical haze episode. Most of the chemical species in PM2.5 showed significant difference between normal and haze days. The highest contributors to PM2.5 were organic carbon (OC), nitrate, and sulfate in haze days and were OC, sulfate, and elemental carbon (EC) in normal days. The concentrations of secondary species such as, NO3(-), SO4(2-), and NH4(+) in haze days were 6.5, 3.9, and 5.3 times higher than those in normal days, respectively, while primary species (EC, Ca(2+), K(+)) show similar increase from normal to haze days by a factor about 2.2-2.4. OC/EC ratio ranged from 2.8 to 6.2 with an average of 4.7 and the estimation on a minimum OC/EC ratio showed that SOC (secondary organic carbon) accounted more than 36.6% for the total organic carbon in haze days. The significantly increase in the secondary species (SOC, NO3(-), SO4(2-), and NH4(+)), especially in NO3(-), caused the worst air quality in this region. Simultaneously, the result illustrated that the serious air pollution in haze episodes was strongly correlated with the meteorological conditions. During the sampling periods, air pollution and visibility had a good relationship with the air mass transport distance; the shorter air masses transport distance, the worse air quality and visibility in Guangzhou, indicating the strong domination of local sources contributing to haze formation. High concentration of the secondary aerosol in haze episodes was likely due to the higher oxidation rates of sulfur and nitrogen species.
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http://dx.doi.org/10.1016/s1001-0742(08)62340-2DOI Listing
October 2009

Measurements and characteristics of nitrogen-containing compounds in atmospheric particulate matter in Beijing, China.

Bull Environ Contam Toxicol 2009 Mar 20;82(3):332-7. Epub 2008 Sep 20.

Department of Environmental Science and Engineering, Tsinghua University, Beijing, People's Republic of China.

The total nitrogen (TN) and water-soluble nitrogenous ions were determined by using CHN Elemental Analyzer and ion chromatography method, respectively, from November 24, 1998 to February 12, 1999 in Beijing. The average concentrations of TN, NH(4) (+) and NO(3) (-) were 10.62 microg N m(-3), 6.67 microg m(-3) and 10.01 microg m(-3), respectively. The total inorganic nitrogen (IN) calculated from NH(4) (+) and NO(3) (-) was 7.45 microg N m(-3), accounting for 70% of TN, i.e., 30% of TN existed as organic nitrogen form (ON). The correlation between ON and other pollution tracers showed that, coal combustion, biomass burning, soil humic matter and secondary formation were the important sources of ON in particulate matter in Beijing.
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http://dx.doi.org/10.1007/s00128-008-9560-0DOI Listing
March 2009

Characteristics of carbonaceous aerosols in Beijing, China.

Chemosphere 2005 Jul;60(3):355-64

Department of Environmental Science and Engineering, Tsinghua University, Beijing 100084, PR China.

Carbonaceous aerosols and PM10 were monitored from September 8 to November 30, 2002, in a semi-urban site (Tsinghua University) in Beijing. Daily concentrations of OC and EC ranged from 7.1 to 65.9 microgCm(-3) and from 1.3 to 26.1 microgCm(-3), with the overall average concentrations of 21.2 microgCm(-3) and 7.3 microgCm(-3), respectively. The diurnal variation of carbonaceous concentrations on 2 h basis presented two-peak trend, which was attributed to the cooperative effect of local meteorological conditions and anthropogenic sources such as traffic exhaust and human outdoor activities. Daily average OC/EC ratio varied between 1.5 and 5.3 with an average of 3.0. Strong correlation between OC and EC (R2=0.8) indicated that their main sources were common. The frequency of OC/EC ratio presented Gaussian normal distribution trend in fall, of which the peak value appeared in the range of 2.8-5. In winter, it presented bi-peak mode, with the first peak near 1.4-1.6, and the second between 2.8 and 5. The high value (2.8-5) implied the SOC formation in both seasons, and the low one probably suggested the primary OC/EC ratio from coal burning in winter. Averagely, PM10 and carbonaceous species exhibited higher concentrations in Wednesday than in other weekdays, which could be ascribed to the low wind speed (1.6 ms(-1)) and high humidity (62.9%). OC was the abundant component accounting for 76% of TC. OC and EC contributed 15% and 5% to PM10, respectively. The estimation on a minimum OC/EC ratio (1.5) basis showed that SOC accounted more than 50% for the total organic carbon. Even in winter, the SOC contribution to OC was also significant, as high as 40%.
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http://dx.doi.org/10.1016/j.chemosphere.2004.12.035DOI Listing
July 2005

Daily concentrations of trace metals in aerosols in Beijing, China, determined by using inductively coupled plasma mass spectrometry equipped with laser ablation analysis, and source identification of aerosols.

Sci Total Environ 2004 Sep;330(1-3):145-58

Department of Applied Chemistry, Faculty of Science and Technology, Keio University, 3-14-1 Hiyoshi, Kohoku-ku, Yokohama 223-8522, Japan.

This paper describes the daily concentrations of trace metals and ionic constituents in the aerosol of Beijing, China from March 2001 to August 2003. Daily PM10 concentrations were also measured from September 2001 to August 2003. The daily average PM10 concentration at Beijing, China from September 2001 to August 2003 was 171+/-117 microg m(-3) (n = 673), which is 5-fold higher than at Yokohama, Japan. Trace metal concentrations were analyzed by using inductively coupled plasma mass spectrometry equipped with a laser ablation sample introduction (LA/ICP-MS), which is a rapid and simultaneous method for multi-element analysis. The daily average metal concentrations in TSP in Beijing from March 2001 to August 2003 were: Al: 3.5+/-2.4 (n = 727), Ti: 0.47+/-0.35 (n = 720), V: 0.013+/-0.010 (n = 716), Cr: 0.019+/-0.015 (n = 618), Mn: 0.24+/-0.16 (n = 730), Fe: 5.5+/-3.9 (n = 728), Co: 0.0046+/-0.0055 (n = 629), Ni: 0.022+/-0.024 (n = 680), Cu: 0.11+/-0.11 (n = 660), Zn: 0.77+/-0.60 (n = 726), As: 0.048+/-0.047 (n = 731), Se: 0.010+/-0.010 (n = 550), Cd: 0.0068+/-0.0082 (n = 709), Sb: 0.033+/-0.036 (n = 687), and Pb: 0.43+/-0.50 (n = 728) (unit, microg m(-3)). All the metal concentrations in TSP in Beijing, China were 1.7-21.8 times higher than those in TSP in the center of Tokyo, Japan. Notably, As concentrations in TSP in Beijing were 20-fold higher than those in Tokyo. Source identification of aerosols in Beijing was carried out by using the chemical mass balance (CMB) receptor model, with the daily concentration of metals in the aerosol. The major primary sources of the aerosol of Beijing were considered to be soil dust and coal combustion. Vehicle exhaust contribution tended to increase.
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http://dx.doi.org/10.1016/j.scitotenv.2004.04.010DOI Listing
September 2004