77 results on '"He KB"'
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2. Assessment of China's virtual air pollution transport embodied in trade by using a consumption-based emission inventory
- Author
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Zhao, HY, Zhang, Q, Guan, DB, Davis, SJ, Liu, Z, Huo, H, Lin, JT, Liu, WD, and He, KB
- Subjects
Climate-Related Exposures and Conditions ,Meteorology & Atmospheric Sciences ,Atmospheric Sciences ,Astronomical and Space Sciences - Abstract
Substantial anthropogenic emissions from China have resulted in serious air pollution, and this has generated considerable academic and public concern. The physical transport of air pollutants in the atmosphere has been extensively investigated; however, understanding the mechanisms how the pollutant was transferred through economic and trade activities remains a challenge. For the first time, we quantified and tracked China's air pollutant emission flows embodied in interprovincial trade, using a multiregional input - output model framework. Trade relative emissions for four key air pollutants (primary fine particle matter, sulfur dioxide, nitrogen oxides and non-methane volatile organic compounds) were assessed for 2007 in each Chinese province. We found that emissions were significantly redistributed among provinces owing to interprovincial trade. Large amounts of emissions were embodied in the imports of eastern regions from northern and central regions, and these were determined by differences in regional economic status and environmental policy. It is suggested that measures should be introduced to reduce air pollution by integrating cross-regional consumers and producers within national agreements to encourage efficiency improvement in the supply chain and optimize consumption structure internationally. The consumption-based air pollutant emission inventory developed in this work can be further used to attribute pollution to various economic activities and final demand types with the aid of air quality models.
- Published
- 2015
3. Assessment of China's virtual air pollution transport embodied in trade by a consumption-based emission inventory
- Author
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Zhao, H. Y., Zhang, Q., Davis, SJ, Guan, Dabo, Liu, Z, Huo, H, Lin, JT, Liu, WD, and He, KB
- Abstract
High anthropogenic emissions from China have resulted in serious air pollution, and it has attracted considerable academic and public concern. The physical transport of air pollutants in the atmosphere has been extensively investigated, however, understanding the mechanisms how the pollutants were transferred through economic and trade activities remains challenge. In this work, we assessed China's virtual air pollutant transport embodied in trade, by using consumption-based accounting approach. We first constructed a consumption-based emission inventory for China's four key air pollutants (primary PM2.5, sulfur dioxide (SO2), nitrogen oxides (NOx) and non-methane volatile organic compounds (NMVOC)) in 2007, based on the bottom-up sectoral emission inventory concerning their production activities – a production-based inventory. We used a multiregional input-output (MRIO) model to integrate the sectoral production-based emissions and the associated economic and trade activities, and finally obtained consumption-based inventory. Unlike the production-based inventory, the consumption-based inventory tracked emissions throughout the supply chain related to the consumption of goods and services and hereby identified the emission flows followed the supply chains. From consumption-based perspective, emissions were significantly redistributed among provinces due to interprovincial trade. Large amount of emissions were embodied in the net imports of east regions from northern and central regions; these were determined by differences in the regional economic status and environmental policies. We also calculated the emissions embodied in exported and imported goods and services. It is found that 15–23% of China's pollutant emissions were related to exports for foreign consumption; that proportion was much higher for central and export-oriented coastal regions. It is suggested that measures should be introduced to reduce air pollution by integrating cross-regional consumers and producers in national agreements to encourage efficiency improvement in the supply chain and optimizing consumption structure internationally. The consumption-based air pollutants emission inventory developed in this work can be further used to attribute pollution to different economic activities and final demand types with the aid of air quality models.
- Published
- 2014
4. The water-soluble ionic composition of PM2.5 in Shanghai and Beijing, China
- Author
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Yao, X.H., Chan, Chak Keung, Fang, Ming, Cadle, S., Chan, T., Mulawa, P., He, KB, Ye, BM, Yao, X.H., Chan, Chak Keung, Fang, Ming, Cadle, S., Chan, T., Mulawa, P., He, KB, and Ye, BM
- Abstract
A year-long field study to characterize the ionic species in PM2.5 was carried out in Shanghai and Beijing, China, in 1999-2000. Weekly samples of PM2.5 were collected using a special low flow rate (0.41 min(-1)) sampler. In Shanghai, SO42- NO3- and NH4+ were the dominant ionic species, which accounted for 46\%, 18\% and 17\% of the total mass of ions respectively. Local SO2 emissions were an important source SO42- in PM2.5 because the SO42- concentration was correlated with the SO2 concentration (r = 0.66,). The relatively stable SO42-/SO2 mass ratio over a large range of temperatures suggests that gas-phase oxidation of SO2 played a minor role in the formation of SO42-. The sum of SO42- and NO3- was highly correlated with NH4+ (r = 0.96), but insufficient ammonium was present to totally neutralize the aerosol. In Beijing, SO42-, NO3- and NH4+ were also the dominant ionic species, constituting 44\%, 25\% and 16\% of the of total mass of water-soluble ions, respectively. Local SO2 emissions were an important source of SO42- in the winter since SO42- was correlated with SO2 (r = 0.83). The low-mass SO42-/SO2 ratio (0.27) during winter, which had low humidity, suggests that gas-phase oxidation of SO2 was a major route of sulfate formation. In the summer, however, much higher mass ratios of SO42-/SO2 (5.6) were observed and were ascribed to in-cloud sulfate formation. The annual average ratio of NO3-/SO42- was 0.4 and 0.6 in Shanghai and in Beijing, respectively, suggesting that stationary emissions were still a dominant source in these two cities. (C) 2002 Elsevier Science Ltd. All rights reserved.
- Published
- 2002
5. The characteristics of PM2.5 in Beijing, China
- Author
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He, KB, Yang, FM, Ma, YL, Zhang, Q., Yao, X.H., Chan, Chak Keung, Cadle, S., Chan, T., Mulawa, P., He, KB, Yang, FM, Ma, YL, Zhang, Q., Yao, X.H., Chan, Chak Keung, Cadle, S., Chan, T., and Mulawa, P.
- Abstract
Weekly PM2.5 samples were simultaneously collected at a residential (Tsinghua University) and a downtown (Chegongzhuang) site in Beijing from July 1999 through September 2000. The ambient mass concentration and chemical composition of the PM2.5 were determined. Analyses included elemental composition, water-soluble ions, and organic and elemental carbon. Weekly PM2.5 mass concentrations ranged from 37 to 357 mug/m(3), with little difference found between the two sites. Seasonal variation Of PM2.5 concentrations was significant, with the highest concentration in the winter and the lowest in the summer. Spring dust storms had a strong impact on the PM2.5. Overall, organic carbon was the most abundant species, constituting no less than 30\% of the total PM2.5 mass at both sites. Concentrations of organic and elemental carbon were 35\% and 16\% higher at Tsinghua University than at Chegongzhuang. Ammonium, nitrate and sulfate were comparable at the sites, accounting for 25-30\% of the PM2.5 mass. (C) 2001 Elsevier Science Ltd. All rights reserved.
- Published
- 2001
6. Response of Harbin aerosol to latest clean air actions in China.
- Author
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Cheng Y, Zhong YJ, Liu JM, Cao XB, Zhang Q, and He KB
- Abstract
Cities in Northeast China, e.g., Harbin, were brought to the forefront of air pollution control by a national-level policy promulgated in 2021, i.e., the Circular on Further Promoting the Pollution Prevention and Control Battle (the FP
3 CB Circular) which aimed at eliminating heavy or severe air pollution events. In this study, we explored the response of Harbin aerosol to the FP3 CB Circular, based on observational results from two campaigns conducted during 2020-2021 and 2021-2022. A clear decreasing trend was identified for the impact of domestic biomass burning between the two winters, presumably driven by the clean heating actions. The 2021-2022 winter was also characterized by reduced formation of secondary organic aerosol but enhanced production of nitrate, which could be attributed to the less humid conditions but higher temperatures, respectively, compared to the 2020-2021 winter. The overall effect of these changes was a decrease in the contribution of organic species to wintertime aerosol in Harbin. In addition, the number of heavy or severe pollution days rebounded in the 2021-2022 winter compared to 2020-2021 (5 vs. 3), indicating that the emissions of primary particles and gaseous precursors must be further reduced to achieve the ambitious goals of the FP3 CB Circular., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier B.V. All rights reserved.)- Published
- 2024
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7. Considerable contribution of secondary aerosol to wintertime haze pollution in new target of the latest clean air actions in China.
- Author
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Cheng Y, Zhong YJ, Liu JM, Cao XB, Yu QQ, Zhang Q, and He KB
- Subjects
- Environmental Monitoring methods, Particulate Matter analysis, China, Seasons, Aerosols analysis, Carbon analysis, Air Pollutants analysis, Air Pollution analysis
- Abstract
Fine particulate matter (PM
2.5 ) in Northeast China was targeted by national-level clean air policy for the first time in 2022, with the release of Action Plan to eliminate heavy air pollution events. In this study, we investigated sources of PM2.5 during three successive winters in Harbin, a megacity in Northeast China, based on observational results from several recent campaigns in 2018-2021. During the 2020-2021 campaign, daytime and nighttime samples were collected in specific months in addition to 24-h integrated measurements, and the two sets of samples were combined in different ways to run a positive matrix factorization model. The source apportionment results suggested that the resolved secondary organic carbon (SOCPMF ) had an uncertainty of ∼12%. Secondary aerosols were found to show the following features for the typical winters without agricultural fires. First, SOCPMF could be properly constrained by results from another widely-used approach for SOC estimation, the elemental carbon-tracer method. Second, secondary PM2.5 calculated using SOCPMF and secondary inorganic ions were generally in line with the independent estimations based on air quality data. Third, secondary components accounted for more than 50% of PM2.5 on average and contributed even more significantly during severe haze episodes, which were the focus of the latest Action Plan. This study also found that the wintertime PM2.5 decreased more slowly during 2017-2021 compared to 2013-2017, by ∼1 and 10 μg/m3 per year, respectively, for the metropolitan area where Harbin is located at. Our results highlighted the importance of secondary aerosols for further improving air quality in Northeast China, and for avoiding heavy pollution as required by the latest Action Plan., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2023 Elsevier Ltd. All rights reserved.)- Published
- 2023
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8. [Synergistic Benefits of Pollution and Carbon Reduction from Air Pollution Control in Hebei Province from 2013 to 2020].
- Author
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Sun SD, Zhang GG, Sun LN, Xu CX, Guo MJ, Cui ZQ, He XJ, Li FB, Song ZQ, Bo Y, and He KB
- Abstract
Recently, China has been facing the dual challenges of air pollution control and carbon emission reduction. Pollution and carbon reduction have become a breakthrough point for green socio-economic transformation. Air pollutant and CO
2 emission inventories provide a tool for monitoring pollution and carbon reduction; however, there have been some problems in previous studies, including incomplete species coverage, different source classifications, and narrow time scales. Based on the unified emission source classification system and estimation method, an emission inventory was developed for Hebei Province from 2013 to 2020, and the emission trends, structure change, driving force, synergistic benefits, and spatial distribution were analyzed. Hebei Province achieved a balance during the study period in socio-economic development and anthropogenic emission control. SO2 emissions decreased rapidly during the "Ten Atmospheric Measures" period. VOCs and NH3 emissions reduction were more significant during the "Blue Sky Defense War" period. The decrease rates of NOx and PM2.5 emissions were relatively stable, and CO2 emissions increased slightly. The coal-fired treatment effectively reduced the air pollutant and CO2 emissions and strengthening the emission standards for key industries reduced SO2 , NOx , and PM2.5 emissions; however, the VOCs emission control requires improvement. Power and residential sources achieved co-reduction of air pollutants and CO2 and reducing residential coal optimized the energy structure, thereby leading to greater synergistic benefits in the residential source. The key pollution and carbon reduction areas in Hebei Province were Shijiazhuang, Tangshan, Handan, Baoding, and Langfang. The methods and conclusions in this study can provide technical and decision-making references for regional pollution and carbon reduction efforts.- Published
- 2023
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9. Agricultural fire impacts on brown carbon during different seasons in Northeast China.
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Cheng Y, Cao XB, Liu JM, Yu QQ, Zhang Q, and He KB
- Abstract
Brown carbon (BrC) represents not only a major component of haze pollution but also a non-negligible contributor to positive radiative forcing, making it a key species for coordinating air quality and climate policies. In China, field observations on BrC remain limited given the highly variable emission sources and meteorological conditions across different regions. Here we focused on the optical properties of BrC in a distinct but rarely studied megacity in Northeast China, which is within a major agricultural region and experiences extremely cold winter. Agricultural fires were evident in April of 2021 and the fall of 2020, although open burning was strictly prohibited. Such emissions enhanced BrC's mass absorption efficiency at 365 nm (MAE
365 ), more efficiently by the fall fires which were inferred to have relatively high combustion efficiencies (CE). After taking CE into consideration, the relationships between MAE365 and the levoglucosan to organic carbon ratio (a measure of the significance of agricultural fire influence) roughly converged for the fire episodes in different seasons, including those identified in February and March of 2019 by a previous campaign. Agricultural fires also influenced the determination of absorption Ångström exponent (AAE), by resulting in non-linearity for BrC's absorption spectra shown on ln-ln scale. Based on three indicators developed by this study, the non-linearity was inferred to be caused by similar chromophores although the fires were characterized by various CE levels in different seasons. In addition, for the samples without significant influence of open burning, coal combustion emissions were identified as the dominant influencing factor for MAE365 , whereas none solid link was found between the solution-based AAE and aerosol source., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2023 Elsevier B.V. All rights reserved.)- Published
- 2023
- Full Text
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10. Enhanced diesel emissions at low ambient temperature: hazardous materials in fine particles.
- Author
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Song WW, Fang WX, Liu H, Li WL, Zhang Z, Li CH, Yu D, Zhao Q, Wang XS, and He KB
- Abstract
The emission of fine particles (PM
2.5 ) from diesel trucks is enhanced by low ambient temperatures, which is a fact that has attracted considerable attention. Carbonaceous matter and polycyclic aromatic hydrocarbons (PAHs) are the dominant hazardous materials in PM2.5 . These materials induce severe adverse effects on air quality and human health and contribute to climate change. The emissions from heavy- and light-duty diesel trucks were tested at an ambient temperature of - 20 to - 13 ℃ and 18-24 ℃. This is the first study to quantify the enhanced carbonaceous matter and PAH emissions from diesel trucks at very low ambient temperatures based on an on-road emission test system. Features affecting diesel emissions, including driving speed, vehicle type, and engine certification level, were considered. The emissions of organic carbon, elemental carbon, and PAHs significantly increased from - 20 to - 13 ℃. The empirical results revealed that intensive abatement of diesel emissions at low ambient temperatures could benefit human health and have a positive influence on climate change. Considering the widespread applications worldwide, an investigation into diesel emissions of carbonaceous matter and PAHs in fine particles at low ambient temperatures is urgently required., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2023 Elsevier B.V. All rights reserved.)- Published
- 2023
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11. Exploring chemical changes of the haze pollution during a recent round of COVID-19 lockdown in a megacity in Northeast China.
- Author
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Cheng Y, Cao XB, Liu JM, Yu QQ, Zhong YJ, Zhang Q, and He KB
- Subjects
- Aerosols analysis, China, Communicable Disease Control, Environmental Monitoring, Humans, Particulate Matter analysis, SARS-CoV-2, Air Pollutants analysis, Air Pollution analysis, COVID-19
- Abstract
COVID-19 rebounded in China in January 2021, with Heilongjiang as one of the worst-affected provinces. This resulted in a new round of lockdown in Harbin, the capital city of Heilongjiang, from 20 January to 22 February of 2021. A field campaign was conducted to explore the responses of haze pollution in Harbin to the lockdown. Levoglucosan was used to reflect biomass burning emissions, while the molar ratio of sulfur (the sum of sulfur dioxide and sulfate) to nitrogen (the sum of nitrogen dioxide and nitrate), i.e., R
S/N , was used as an indicator for the relative importance of coal combustion and vehicle emissions. Based on a synthesis of the levoglucosan and RS/N results, reference period was selected with minimal influences of non-lockdown-related emission variations. As indicated by the almost unchanged sulfur dioxide concentrations, coal combustion emissions were relatively stable throughout the lockdown and reference periods, presumably because the associated activities, e.g., heating supply, power generation, etc., were usually uninterruptible. On the other hand, as suggested by the increase of RS/N , vehicle emissions were considerably reduced during lockdown, likely due to the stay-at-home orders. Compared to results from the reference samples, the lockdown period exhibited higher levels of ozone and various indicators for secondary aerosol formation, pointing to an enhancement of secondary pollution. In addition, photochemistry-related reactions in aqueous phase appeared to be present during the lockdown period, which have not been reported in the frigid atmosphere over Northeast China., (Copyright © 2022 Elsevier Ltd. All rights reserved.)- Published
- 2022
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12. Primary nature of brown carbon absorption in a frigid atmosphere with strong haze chemistry.
- Author
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Cheng Y, Cao XB, Liu JM, Yu QQ, Wang P, Yan CQ, Du ZY, Liang LL, Zhang Q, and He KB
- Subjects
- Aerosols analysis, Biomass, Environmental Monitoring, Seasons, Air Pollutants analysis, Carbon analysis
- Abstract
Severe haze hovered over Harbin during the heating season of 2019-2020, making it one of the ten most polluted Chinese cities in January of 2020. Here we focused on the optical properties and sources of brown carbon (BrC) during the extreme atmospheric pollution periods. Enhanced formation of secondary BrC (BrC
sec ) was evident as relative humidity (RH) became higher, accompanied with a decrease of ozone but concurrent increases of aerosol water content and secondary inorganic aerosols. These features were generally similar to the characteristics of haze chemistry observed during winter haze events in the North China Plain, and indicated that heterogeneous reactions involving aerosol water might be at play in the formation of BrCsec , despite the low temperatures in Harbin. Although BrCsec accounted for a substantial fraction of brown carbon mass, its contribution to BrC absorption was much smaller (6 vs. 28%), pointing to a lower mass absorption efficiency (MAE) of BrCsec compared to primary BrC. In addition, emissions of biomass burning BrC (BrCBB ) were inferred to increase with increasing RH, coinciding with a large drop of temperature. Since both the less absorbing BrCsec and the more absorbing BrCBB increased as RH became higher, the MAE of total BrC were largely unchanged throughout the measurement period. This study unfolded the contrast in the source apportionment results of BrC mass and absorption, and could have implications for the simulation of radiative forcing by brown carbon., (Copyright © 2021 Elsevier Inc. All rights reserved.)- Published
- 2022
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13. New open burning policy reshaped the aerosol characteristics of agricultural fire episodes in Northeast China.
- Author
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Cheng Y, Cao XB, Liu JM, Yu QQ, Zhong YJ, Geng GN, Zhang Q, and He KB
- Subjects
- Aerosols analysis, Biomass, China, Environmental Monitoring, Particulate Matter analysis, Policy, Seasons, Air Pollutants analysis, Fires
- Abstract
The massive agricultural sector in the Northeast Plain, which is of great importance for the food security in China, results in a huge amount of crop residues and thus substantial concern on haze pollution due to biomass burning (BB). To seek for effective control measures on BB emissions, a dramatic transition of open burning policy occurred in Heilongjiang Province, from the "legitimate burning" policy released in 2018 to the "strict prohibition" policy implemented in 2019 and beyond. Here we explored the BB aerosols during 2020-2021 in Harbin, the capital city of Heilongjiang. Although open burning was strictly prohibited by mandatory bans, agricultural fires were not actually eliminated, as indicated by the levoglucosan levels and fire count results. In general, the BB aerosols in Harbin were attributed to the overlaying of household burning and agricultural fire emissions. The former factor laid the foundation of biomass burning impacts, with BB contributions to organic carbon and elemental carbon (f
BBOC and fBBEC ) of 35 and 47%, respectively. The latter further enhanced the BB impacts during specific episodes breaking out in the spring of 2021 as well as the fall of 2020, when fBBOC and fBBEC increased to 64 and 57%, respectively. In addition, comparing to the fires of 2018-2019 which occurred in winter (in response to the "legitimate burning" policy), the agricultural fires were shifted to spring and fall in the 2020-2021 campaign, accompanied with an increase of combustion efficiency. This study illustrated how the agricultural fire emissions were influenced by the transition of open burning policy., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2021 Elsevier B.V. All rights reserved.)- Published
- 2022
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14. Source apportionment of atmospheric particle number concentrations with wide size range by nonnegative matrix factorization (NMF).
- Author
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Liang CS, Yue D, Wu H, Shi JS, and He KB
- Subjects
- Environmental Monitoring, Particle Size, Particulate Matter analysis, Air Pollutants analysis, Air Pollution analysis
- Abstract
Quantifying the sources of atmospheric particles is essential to air quality control but remains challenging, especially for the source apportionment of particles based on number concentration with wide size range. Here, particle number concentrations (PNC) with size range 19-20,000 nm involving four modes Nucleation, Aitken, Accumulation, and Coarse are used to do source apportionment of PNC at the Guangdong Atmospheric Supersite (Heshan) during July-October 2015 by nonnegative matrix factorization (NMF) with 6 factors. For July 2015, separated source apportionments for three different size ranges from collocated instruments nano scanning mobility particle sizer (NSMPS), SMPS, and aerodynamic particle sizer (APS) and for two different size ranges (below and above 100 nm) show similar quantitative source information with that for the one whole size range. The mean absolute difference of contribution percentages of total particle number concentrations (TPNC) based on 5 unique apportioned sources is 5.6 % (4.3-7.6 %) for the instrument segregated apportionment and 4.2 % (0-5.3 %) for the size range segregated apportionment respectively, relative to the one whole apportionment. Moreover, the contribution percentages of TPNC are close to the weighted sum of contribution percentages of all size bins, with a mean absolute difference of 1.1 % (0-3.4 %). In both these two aspects, the consistency among different technical paths proves the matrix factorization by NMF is practically desirable and the simplicity of reducing some steps or calculations saves time. Besides, dust can be identified with the wide size range including larger than 3000 nm. Six apportioned sources in the 4 months are Accumulation (32.4 %), Nucleation (20.0 %), Aitken (15.2 %), traffic (14.6 %), dust (10.6 %), and Coarse (7.1 %). Therefore, NMF would serve as a promising tool for PNC source apportionment with wide size range and conducting the apportionment with the whole size range in one matrix factorization procedure and using the single TPNC contribution percentage are feasible., (Copyright © 2021 Elsevier Ltd. All rights reserved.)
- Published
- 2021
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15. [Transmission of Coronavirus via Aerosols and Influence of Environmental Conditions on Its Transmission].
- Author
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Li X, Jiang JK, Wang DB, Deng JG, He KB, and Hao JM
- Subjects
- Aerosols, Humans, SARS-CoV-2, COVID-19, Pandemics
- Abstract
The COVID-19 pandemic has endangered human health and production since 2019. As an emerging disease caused by SARS-CoV-2, its potential transmissibility via aerosols has caused heated debate. This work summarizes the current research findings on virus aerosol generation, aerodynamic properties, and environmental influencing factors on their survivability in order to elucidate coronavirus transmission via aerosols. The occurrence and distinction of SARS-CoV-2, SARS-CoV-1, and MERS-CoV in real atmospheric environments are summarized. The deficiencies of existing research and directions for necessary future research on confirming the airborne transmission mechanism of coronavirus as well as the need for multidisciplinary research are discussed.
- Published
- 2021
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16. [Contributors to Air Pollutant Emission Changes in Autumn and Winter in Beijing-Tianjin-Hebei and Surrounding Areas].
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Tang Q, Zheng B, Xue WB, Zhang Q, Lei Y, and He KB
- Abstract
Based on the air pollution emission inventory technical methodology, this study conducted a quantitative analysis on the changes in major air pollutant emissions in Beijing-Tianjin-Hebei and its surrounding areas from the 'New Year Haze' in the autumn and winter of 2016-2017 to the 'Pandemic Haze' in the autumn and winter of 2019-2020. The contributions of the implementation of air pollution prevention and control policies and the COVID-19 pandemic to major air pollutant emission reductions were studied, and their impacts on the regional air quality under adverse meteorological conditions were simulated using an air quality model. The results showed that from the 'New Year Haze' in Dec 2016-Jan 2017 to the 'Pandemic Haze' in Jan-Feb 2020, the major air pollutant emissions in the region had dropped by approximately 50%, and the average concentration of PM
2.5 was potentially reduced by more than 40% under adverse meteorological conditions. The most effective emission reduction measures included the clean heating project and raising the standards in key industrial sectors, such as the iron and steel industry, coal-fired boilers, and power plants, which contributed 67.1% and 53.4% of the emission reductions in SO2 and PM2.5 , respectively. The COVID-19 pandemic predominantly affected the mobile sources and light industry, which contributed 71.9% and 68.2% of the emission reductions in NOx and VOCs, respectively. The implementation of air pollution prevention and control policies contributed substantially to the improvement of regional air quality, which effectively reduced the intensity and extent of the heavy pollution process under unfavorable meteorological conditions. The regional average PM2.5 concentration was reduced by 26%, and the number of days experiencing heavy pollution decreased by 44%. Due to the impacts of the COVID-19 pandemic, the average PM2.5 concentration in the region was reduced by an additional 24%, and the duration and extent of heavy pollution decreased even further.- Published
- 2021
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17. Strong biomass burning contribution to ambient aerosol during heating season in a megacity in Northeast China: Effectiveness of agricultural fire bans?
- Author
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Cheng Y, Yu QQ, Liu JM, Du ZY, Liang LL, Geng GN, Zheng B, Ma WL, Qi H, Zhang Q, and He KB
- Abstract
Sustainable use of crop residues remains a challenge in main agricultural regions of China such as the Northeast Plain. Here we investigated the impacts of biomass burning on fine particle (PM
2.5 ) during a six-month long heating season in the Harbin-Changchun (HC) metropolitan area, China's only national-level city cluster located in the severe cold climate region. Temporal variation of PM2.5 was found to coincide with that of levoglucosan. This was attributed to the strong contribution of biomass burning to organic aerosol (the dominant component in PM2.5 ), as supported by the source apportionment results and high levoglucosan-to-organic carbon (OC) ratios. Furthermore, the variation of biomass burning contribution was inferred to be driven mainly by agricultural fires with relatively low combustion efficiencies, based on a synthesis of the relationship between OC and elemental carbon (EC), the dependence of EC on carbon monoxide, and the relative abundances of different tracers for biomass burning. Nitrate formation was enhanced during biomass burning episodes whereas no evidence was observed to indicate enhanced sulfate formation or net increase of OC mass due to secondary formation. This study demonstrates the importance of open burning as a source of haze pollution in the HC region., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2020 Elsevier B.V. All rights reserved.)- Published
- 2021
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18. Model vs. observation discrepancy in aerosol characteristics during a half-year long campaign in Northeast China: The role of biomass burning.
- Author
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Cheng Y, Yu QQ, Liu JM, Zhu S, Zhang M, Zhang H, Zheng B, and He KB
- Subjects
- Aerosols analysis, Biomass, China, Cities, Environmental Monitoring, Particulate Matter analysis, Seasons, Air Pollutants analysis, Air Pollution
- Abstract
Complex air pollutant sources and distinct meteorological conditions resulted in unique wintertime haze pollution in the Harbin-Changchun (HC) metropolitan area, China's only national-level city cluster located in the severe cold climate region. In this study, field observation and air quality modeling were combined to investigate fine particulate matter (PM
2.5 ) pollution during a six-month long heating season in HC's central city (Harbin). The model significantly underpredicted PM2.5 and organic carbon (by up to ∼230 μg/m3 and 110 μgC/m3 , respectively, in terms of daily average) when levoglucosan concentrations were above 0.5 μg/m3 . Based on a synthesis of levoglucosan concentrations and fire counts, the large gaps were attributed to underestimation of open burning emissions by the model. However, the model tended to overpredict elemental carbon (more significantly at higher NO2 ), likely pointing to an overestimation of vehicle emissions. With increasing levoglucosan, the difference between observed and simulated nitrate (nitrateobs ‒ nitratemod , i.e., Δnitrate) showed a transition from negative to positive values. The positive Δnitrate were attributed to underprediction of the open-burning related nitrate, whereas the negative Δnitrate were likely caused by overprediction of nitrate from other sources (presumably vehicle emissions). The dependence of Δnitrate on levoglucosan indicated that with stronger impact of open burning, the overprediction effect was gradually offset and finally overwhelmed. Influence of open burning on sulfate formation was evident as well, but less apparent compared to nitrate. This study illustrates how the uncertainties in open burning emissions will influence PM2.5 simulation, on not only primary components but also secondary species., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2020 Elsevier Ltd. All rights reserved.)- Published
- 2021
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19. Secondary inorganic aerosol during heating season in a megacity in Northeast China: Evidence for heterogeneous chemistry in severe cold climate region.
- Author
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Cheng Y, Yu QQ, Liu JM, Du ZY, Liang LL, Geng GN, Ma WL, Qi H, Zhang Q, and He KB
- Subjects
- Aerosols analysis, Beijing, China, Cities, Heating, Humidity, Nitrates analysis, Nitrogen Dioxide, Nitrogen Oxides analysis, Particulate Matter analysis, Seasons, Sulfates analysis, Air Pollutants analysis, Cold Climate, Environmental Monitoring
- Abstract
The characteristics of secondary inorganic aerosol including sulfate, nitrate and ammonium (SNA) were investigated during a six-month long heating season in the Harbin-Changchun metropolitan area, i.e., China's only national-level city cluster located in the severe cold climate region. The contribution of SNA to fine particulate matter (PM
2.5 ) tended to decrease with increasing PM2.5 concentration, opposite to the trend repeatedly observed during winter in Beijing. Heterogeneous sulfate formation was still evident when the daily average temperature was as low as below -10 °C, with the preconditions of high relative humidity (RH; above ∼80%) and high nitrogen dioxide (above ∼60 μg/m3 ). Both the sulfur oxidation ratio (SOR) and nitrogen oxidation ratio (NOR) were enhanced at high RH, reaching ∼0.3. However, the high RH conditions were not commonly seen during the heating season, which should be responsible for the overall lack of linkage between the SNA contribution and PM2.5 temporal variation., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2020 Elsevier Ltd. All rights reserved.)- Published
- 2020
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20. Efficient data preprocessing, episode classification, and source apportionment of particle number concentrations.
- Author
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Liang CS, Wu H, Li HY, Zhang Q, Li Z, and He KB
- Abstract
Number concentration is an important index to measure atmospheric particle pollution. However, tailored methods for data preprocessing and characteristic and source analyses of particle number concentrations (PNC) are rare and interpreting the data is time-consuming and inefficient. In this method-oriented study, we develop and investigate some techniques via flexible conditions, C++ optimized algorithms, and parallel computing in R (an open source software for statistics and graphics) to tackle these challenges. The data preprocessing methods include deletions of variables and observations, outlier removal, and interpolation for missing values (NA). They do better in cleaning data and keeping samples and generate no new outliers after interpolation, compared with previous methods. Besides, automatic division of PNC pollution events based on relative values suites PNC properties and highlights the pollution characteristics related to sources and mechanisms. Additionally, basic functions of k-means clustering, Principal Component Analysis (PCA), Factor Analysis (FA), Positive Matrix Factorization (PMF), and a newly-introduced model NMF (Non-negative Matrix Factorization) were tested and compared in analyzing PNC sources. Only PMF and NMF can identify coal heating and produce more explicable results, meanwhile NMF apportions more distinctly and runs 11-28 times faster than PMF. Traffic is interannually stable in non-heating periods and always dominant. Coal heating's contribution has decreased by 40%-86% in recent 5 heating periods, reflecting the effectiveness of coal burning control., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2020. Published by Elsevier B.V.)
- Published
- 2020
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21. Integration of field observation and air quality modeling to characterize Beijing aerosol in different seasons.
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Liu JM, Wang PF, Zhang HL, Du ZY, Zheng B, Yu QQ, Zheng GJ, Ma YL, Zheng M, Cheng Y, Zhang Q, and He KB
- Subjects
- Beijing, Biomass, Carbon analysis, China, Environmental Monitoring methods, Particulate Matter analysis, Aerosols analysis, Air Pollutants analysis, Air Pollution analysis, Seasons
- Abstract
Fine particulate matter (PM
2.5 ) pollution in Beijing was investigated based on field observation and air quality modeling. Measurement results showed that when using elemental carbon (EC) as the reference component, concurrent increases were observed in the relative abundances of sulfate, nitrate, organic carbon (OC) and water-soluble organic carbon (WSOC) when RH exceeded ∼65% during winter. The observed increases could not be explained by variations of primary biomass burning emissions, instead they likely pointed to heterogeneous chemistry and presumably indicated that formation of secondary inorganic and organic aerosols might be related during winter haze events in Beijing. Large gaps were found in winter when comparing the observational and modeling results. In summer, RH exhibited little influence on the observed sulfate/EC, OC/EC or WSOC/EC, and the observed and modeled results were in general comparable for the concentrations of sulfate, EC and OC. This study suggests that distinct yet poorly-understood atmospheric chemistry may be at play in China's winter haze events, and it could be a substantial challenge to properly incorporate the related mechanisms into air quality models., (Copyright © 2019 Elsevier Ltd. All rights reserved.)- Published
- 2020
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22. Non-mono-exponential diffusion models for assessing early response of liver metastases to chemotherapy in colorectal Cancer.
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Zhou Y, Zhang HX, Zhang XS, Sun YF, He KB, Sang XQ, Zhu YM, and Kuai ZX
- Subjects
- Aged, Colorectal Neoplasms diagnostic imaging, Colorectal Neoplasms pathology, Female, Humans, Liver Neoplasms diagnostic imaging, Liver Neoplasms secondary, Male, Middle Aged, Survival Analysis, Colorectal Neoplasms drug therapy, Diffusion Magnetic Resonance Imaging methods, Liver Neoplasms drug therapy
- Abstract
Background: Preoperative chemotherapy is becoming standard therapy for liver metastasis from colorectal cancer, so early assessment of treatment response is crucial to make a reasonable therapeutic regimen and avoid overtreatment, especially for patients with severe side effects. The role of three non-mono-exponential diffusion models, such as the kurtosis model, the stretched exponential model and the statistical model, were explored in this study to early assess the response to chemotherapy in patients with liver metastasis from colorectal cancer., Methods: Thirty-three patients diagnosed as colorectal liver metastasis were evaluated in this study. Diffusion-weighted images with b values (0, 200, 500, 1000, 1500, 2000 s/mm
2 ) were acquired at 3.0 T. The parameters (ADCk , K, DDC,α, Ds and σ) were derived from three non-mono-exponential models (the kurtosis, stretched exponential and statistical models) as well as their corresponding percentage changes before and after chemotherapy. The difference in above parameters between the response and non-response groups were analyzed with independent-samples T-test (normality) and Mann-Whitney U-test (non-normality). Meanwhile, receiver operating characteristic curve (ROC) analyses were performed to assess the response to chemotherapy., Results: Significantly lower values of K (the kurtosis coefficient derived from the kurtosis model) and σ (the width of diffusion coefficient distribution in the statistical model) (P < 0.05) were observed in the respond group before treatment, as well as higher ΔK and Δσ values (P < 0.05) after the first cycle of chemotherapy were also found compared with the non-respond group. ROC analyses showed the K value acquired before treatment had the highest diagnostic performance (0.746) in distinguishing responders from non-responders. Furthermore, the high sensitivity (100%) and accuracy (76.3%) from the K value before treatment was found in assessing the response of colorectal liver metastasis to chemotherapy., Conclusions: The non-mono-exponential diffusion models may be able to predict early response to chemotherapy in patients with colorectal liver metastasis.- Published
- 2019
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23. Uncertainties in thermal-optical measurements of black carbon: Insights from source and ambient samples.
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Liu JM, Du ZY, Liang LL, Yu QQ, Shen GF, Ma YL, Zheng M, Cheng Y, and He KB
- Abstract
Black carbon (BC) is important due to its complex influences on the environment and on climate in particular. However, reported BC data are largely dependent on measurement techniques due to the multitude of measurement principles. Here we focused on thermal-optical method which has been widely used to determine BC mass (as elemental carbon, EC). Several factors influencing EC measurement were investigated. Results from source samples representing vehicle engine emissions pointed to a continuum of EC components in thermal stability and provided direct observational evidence for the premature evolution of EC in inert atmosphere. It was also found that EC masses may be substantially underestimated for the vehicle exhaust samples if the adopted protocol requires an oxidizing atmosphere to define the split point between organic carbon (OC) and EC. Results from a field campaign conducted during winter in Beijing showed that the optical attenuation (ATN; i.e., the filter transmittance signal, I) was largely saturated for the samples with relatively high loadings, indicating their EC results were unreliable. Improved measurement of EC was achieved by extracting these heavily loaded filters using methanol, given that ATN was considerably reduced by the extraction and, moreover, saturation of ATN (or I) became not evident for the extracted samples. The methanol extraction also significantly reduced the transformation of OC to char-OC, by removing the majority (i.e., ~85%) of the deposited organic aerosols. Higher EC were measured for the extracted samples compared with the untreated ones, indicating that EC tends to be underestimated due to the charring-induced uncertainties. In addition, the methanol extraction largely reduced the inter-protocol discrepancy in the EC measurement results. Similar effects of methanol extraction have been observed during summer in Beijing, despite the seasonal variations of aerosol sources and compositions. This study indicates the potential benefits of methanol extraction for EC measurement., (Copyright © 2018 Elsevier B.V. All rights reserved.)
- Published
- 2019
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24. Analysis of the origins of black carbon and carbon monoxide transported to Beijing, Tianjin, and Hebei in China.
- Author
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Liu XY, He KB, Zhang Q, Lu ZF, Wang SW, Zhang YX, and Streets DG
- Abstract
A novel back-trajectory approach was adopted to determine the origins of black carbon (BC) and carbon monoxide (CO) transported to Beijing, Tianjin and Hebei. Results showed that the transport efficiency was controlled mainly by mid-latitude westerlies in winter, the South Asian monsoon in summer and prevailing westerly and northwesterly winds in spring and autumn. Hebei was identified as the most important source region of both BC (respectively accounting for 55% and 49%) and CO (39% and 38%) transported to Beijing and Tianjin. Inner Mongolia contributed more to the effective emission intensity (EEI) in winter than in summer for both BC and CO transported to Beijing and Tianjin. Shandong was responsible for higher EEI in summer than in winter. The six provinces making the greatest contributions to BC transported to Hebei were Shandong (19%), Shanxi (19%), Inner Mongolia (17%), Beijing (11%), Henan (11%), and Tianjin (10%), whereas those making the greatest contributions to CO transported to Hebei were Shandong (20%), Inner Mongolia (10%), Tianjin (9%), Henan (9%), Shanxi (9%), and Beijing (8%). In summary, Hebei, Inner Mongolia, Shandong, Tianjin and Shanxi were determined as the dominant source regions of not only BC but also CO transported to Beijing. Hebei, Shandong, Beijing, Inner Mongolia, Henan, Liaoning and Shanxi were relatively important source regions for Tianjin. Shandong, Shanxi, Inner Mongolia, Beijing, Henan, Tianjin, Liaoning, Jiangsu and Anhui were the main source regions for Hebei. Residential and industrial sectors were the dominant sectors for BC and CO transported to the receptors, respectively. These results are consistent with the results of previous studies. Finally, comparing the observed ΔBC/ΔCO ratio with the enhancement ratio of the EEI of BC with that of CO (ΔEEI
BC /ΔEEICO ) at Miyun site, we further confirmed that the EEI can be used to represent the amounts of BC and CO reaching receptors., (Copyright © 2018. Published by Elsevier B.V.)- Published
- 2019
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25. [Patterns of Mortality from Air Pollutant Emissions in China's Coal-fired Power Plants].
- Author
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Qin Y, Zhang Q, Li X, Zhao HY, Tong D, Zheng YX, Geng GN, and He KB
- Subjects
- Air Pollutants, China, Humans, Particulate Matter adverse effects, Air Pollution adverse effects, Coal, Mortality, Power Plants
- Abstract
Based on the high-resolution coal-fired power plant emission database, GEOS-Chem Adjoint, a global-regional nested atmospheric chemistry model and its adjoint were applied to analyze PM
2.5 -related premature deaths caused by the power sector in six grid regions of China due to air pollutant emissions and subsequent pollution. The results show that power sector-related PM2.5 pollution caused 106000 (95% CI:68000-132000) premature deaths in 2010, accounting for 9.8% of China's anthropogenic PM2.5 -related premature deaths. The health loss intensity (defined as number of premature deaths caused by a unit of power generation) of small and old units is significantly higher than that of large and new units:units with a capacity below 100 MW reach 62 people·(TW·h)-1 , 2.8 times that of units with a capacity above 600 MW. Similarly, the health loss intensity of units older than thirty years is 58 people·(TW·h)-1 , 2.1 times that of new units. From the perspective of regional grids, the health impact index of Central China is relatively large, reaching 77 people·(TW·h)-1 . Further analysis reveals that transregional power transmission led to a net increase of 680 premature deaths compared with the scenario without transmission in 2010. Our study implies that China should accelerate the pace of phasing out small and old units and optimize the power transmission distribution between grid regions to reduce the overall level of pollution and health losses.- Published
- 2018
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26. Determination of Hepatocellular Carcinoma and Characterization of Hepatic Focal Lesions with Adaptive Multi-Exponential Intravoxel Incoherent Motion Model.
- Author
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Zhang HX, Zhang XS, Kuai ZX, Zhou Y, Sun YF, Ba ZC, He KB, Sang XQ, Yao YF, Chu CY, and Zhu YM
- Abstract
Purpose: To distinguish hepatocellular carcinoma (HCC) from other types of hepatic lesions with the adaptive multi-exponential IVIM model., Methods: 94 hepatic focal lesions, including 38 HCC, 16 metastasis, 12 focal nodular hyperplasia, 13 cholangiocarcinoma, and 15 hemangioma, were examined in this study. Diffusion-weighted images were acquired with 13 b values (b = 0, 3, …, 500 s/mm
2 ) to measure the adaptive multi-exponential IVIM parameters, namely, pure diffusion coefficient (D), diffusion fraction (fd ), pseudo-diffusion coefficient (Di *) and perfusion-related diffusion fraction (fi ) of the ith perfusion component. Comparison of the parameters of and their diagnostic performance was determined using Mann-Whitney U test, independent-sample t test, one-way analysis of variance, Z test and receiver-operating characteristic analysis., Results: D, D1 * and D2 * presented significantly difference between HCCs and other hepatic lesions, whereas fd , f1 and f2 did not show statistical differences. In the differential diagnosis of HCCs from other hepatic lesions, D2 * (AUC, 0.927) provided best diagnostic performance among all parameters. Additionally, the number of exponential terms in the model was also an important indicator for distinguishing HCCs from other hepatic lesions. In the benign and malignant analysis, D gave the greatest AUC values, 0.895 or 0.853, for differentiation between malignant and benign lesions with three or two exponential terms. Most parameters were not significantly different between hypovascular and hypervascular lesions. For multiple comparisons, significant differences of D, D1 * or D2 * were found between certain lesion types., Conclusion: The adaptive multi-exponential IVIM model was useful and reliable to distinguish HCC from other hepatic lesions., (Copyright © 2018 The Authors. Published by Elsevier Inc. All rights reserved.)- Published
- 2018
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27. The characteristics of carbonaceous aerosol in Beijing during a season of transition.
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Liu JM, Du ZY, Gordon M, Liang LL, Ma YL, Zheng M, Cheng Y, and He KB
- Subjects
- Beijing, Carbon chemistry, Particulate Matter analysis, Seasons, Water chemistry, Aerosols analysis, Air Pollutants analysis, Air Pollution analysis, Environmental Monitoring methods
- Abstract
Carbonaceous aerosol was measured during fall of 2010 in Beijing. Daily variation of organic carbon (OC) was found to coincide with that of relative humidity (RH), and the OC to elemental carbon (EC) ratios were more than doubled during the more humid periods (RH above 0.75) compared to other conditions. This large increase in OC/EC could not be explained by the variations of primary biomass burning emissions but was accompanied by a five-fold increase in the sulfate to EC ratio. It was then inferred that secondary organic aerosol (SOA) formation was enhanced under the more humid conditions, presumably through aqueous-phase processes. This enhanced SOA formation might be partially associated with particles externally mixed with black carbon, as indicated by the RH-dependent relationships between aerosol optical attenuation and EC loading. In addition, organic aerosols exhibited different properties between the more humid and the other periods, such that they were less volatile and charred more significantly during thermal-optical analysis in the former case. These differences coincided with the evidence of enhanced SOA formation under the more humid conditions. This study highlights the necessity of incorporating aqueous-phase chemistry into air quality models for SOA., (Copyright © 2018 Elsevier Ltd. All rights reserved.)
- Published
- 2018
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28. Global Sources of Fine Particulate Matter: Interpretation of PM 2.5 Chemical Composition Observed by SPARTAN using a Global Chemical Transport Model.
- Author
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Weagle CL, Snider G, Li C, van Donkelaar A, Philip S, Bissonnette P, Burke J, Jackson J, Latimer R, Stone E, Abboud I, Akoshile C, Anh NX, Brook JR, Cohen A, Dong J, Gibson MD, Griffith D, He KB, Holben BN, Kahn R, Keller CA, Kim JS, Lagrosas N, Lestari P, Khian YL, Liu Y, Marais EA, Martins JV, Misra A, Muliane U, Pratiwi R, Quel EJ, Salam A, Segev L, Tripathi SN, Wang C, Zhang Q, Brauer M, Rudich Y, and Martin RV
- Subjects
- Aerosols, Dust, Environmental Monitoring, Air Pollutants, Particulate Matter
- Abstract
Exposure to ambient fine particulate matter (PM
2.5 ) is a leading risk factor for the global burden of disease. However, uncertainty remains about PM2.5 sources. We use a global chemical transport model (GEOS-Chem) simulation for 2014, constrained by satellite-based estimates of PM2.5 to interpret globally dispersed PM2.5 mass and composition measurements from the ground-based surface particulate matter network (SPARTAN). Measured site mean PM2.5 composition varies substantially for secondary inorganic aerosols (2.4-19.7 μg/m3 ), mineral dust (1.9-14.7 μg/m3 ), residual/organic matter (2.1-40.2 μg/m3 ), and black carbon (1.0-7.3 μg/m3 ). Interpretation of these measurements with the GEOS-Chem model yields insight into sources affecting each site. Globally, combustion sectors such as residential energy use (7.9 μg/m3 ), industry (6.5 μg/m3 ), and power generation (5.6 μg/m3 ) are leading sources of outdoor global population-weighted PM2.5 concentrations. Global population-weighted organic mass is driven by the residential energy sector (64%) whereas population-weighted secondary inorganic concentrations arise primarily from industry (33%) and power generation (32%). Simulation-measurement biases for ammonium nitrate and dust identify uncertainty in agricultural and crustal sources. Interpretation of initial PM2.5 mass and composition measurements from SPARTAN with the GEOS-Chem model constrained by satellite-based PM2.5 provides insight into sources and processes that influence the global spatial variation in PM2.5 composition.- Published
- 2018
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29. Shipping emission forecasts and cost-benefit analysis of China ports and key regions' control.
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Liu H, Meng ZH, Shang Y, Lv ZF, Jin XX, Fu ML, and He KB
- Subjects
- Air Pollutants analysis, Air Pollutants economics, Air Pollution analysis, China, Cost-Benefit Analysis, Environmental Monitoring economics, Particulate Matter analysis, Particulate Matter economics, Ships statistics & numerical data, Sulfur analysis, Air Pollution economics, Ships economics
- Abstract
China established Domestic Emission Control Area (DECA) for sulphur since 2015 to constrain the increasing shipping emissions. However, future DECA policy-makings are not supported due to a lack of quantitive evaluations. To investigate the effects of current and possible Chinese DECAs policies, a model is presented for the forecast of shipping emissions and evaluation of potential costs and benefits of an DECA policy package set in 2020. It includes a port-level and regional-level projection accounting for shipping trade volume growth, share of ship types, and fuel consumption. The results show that without control measures, both SO
2 and particulate matter (PM) emissions are expected to increase by 15.3-61.2% in Jing-Jin-Ji, the Yangtze River Delta, and the Pearl River Delta from 2013 to 2020. However, most emissions can be reduced annually by the establishment of a DECA that depends on the size of the control area and the fuel sulphur content limit. Costs range from 0.667 to 1.561 billion dollars (control regional shipping emissions) based on current fuel price. A social cost method shows the regional control scenarios benefit-cost ratios vary from 4.3 to 5.1 with large uncertainty. Chemical transportation model combined with health model method is used to get the monetary health benefits and then compared with the results from social cost method. This study suggests that Chinese DECAs will reduce the projected emissions at a favorable benefit-cost ratio, and furthermore proposes policy combinations that provide high cost-effective benefits as a reference for future policy-making., (Crown Copyright © 2018. Published by Elsevier Ltd. All rights reserved.)- Published
- 2018
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30. Characteristics and formation of typical winter haze in Handan, one of the most polluted cities in China.
- Author
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Yang S, Ma YL, Duan FK, He KB, Wang LT, Wei Z, Zhu LD, Ma T, Li H, and Ye SQ
- Abstract
Handan, a city within the North China Plain (NCP) region, is a typical city influenced by regional particulate matter (PM) pollution. One-year hourly semi-continuous observation was carried out in 2015 in Handan with the aim of identifying the chemical composition and variations in PM
2.5 . Moreover, the concentration of aerosol precursors, meteorological factors, and secondary transformations are considered. The results demonstrate that the annual average PM2.5 concentration in Handan is 122.35μgm-3 , approximately 3.5 times higher than the Chinese National Ambient Air Quality Standard (NAAQS) (35μgm-3 ), and only 12days were below the guideline. As expected, PM concentrations are highest in winter, especially in December. In addition, we measure the concentrations of five species commonly found in PM, nitrate, sulfate, ammonium, inorganic carbon, and organic carbon. Of these, nitrate and sulfate account for the largest proportion of PM2.5 ; during periods when the PM2.5 concentration was below 400μgm-3 , nitrate dominates, while above this concentration, sulfate dominate. This is likely related to the nitrogen and sulfur oxidation ratios, which are in turn, especially the sulfur oxidation ratio, driven by high relative humidity (>60%). In addition, haze events are driven by other meteorological conditions, wind speed and direction, where low wind speeds from the south and southwest enable pollutant accumulation, which are infrequently interspersed with brief periods with high wind speeds that promote pollutant dispersal. Even though Handan is among the ten most polluted cities in China with regard to air pollution, few studies beyond model simulations have analyzed air pollutant concentrations in this city. Therefore, this study makes a significant contribution to understanding air pollution in Handan, which can further be used to improve our understanding of regional pollution in the highly populated North China Plain. These results have implications for the creation of policies and legislation, as well as other pollution control measures., (Copyright © 2017 Elsevier B.V. All rights reserved.)- Published
- 2018
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31. Brown and black carbon in Beijing aerosol: Implications for the effects of brown coating on light absorption by black carbon.
- Author
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Cheng Y, He KB, Engling G, Weber R, Liu JM, Du ZY, and Dong SP
- Abstract
Brown carbon (BrC) is increasingly included in climate models as an emerging category of particulate organic compounds that can absorb solar radiation efficiently at specific wavelengths. Water-soluble organic carbon (WSOC) has been commonly used as a surrogate for BrC; however, it only represents a limited fraction of total organic carbon (OC) mass, which could be as low as about 20% in urban atmosphere. Using methanol as the extraction solvent, up to approximately 90% of the OC in Beijing aerosol was isolated and measured for absorption spectra over the ultraviolet-to-visible wavelength range. Compared to methanol-soluble OC (MSOC), WSOC underestimated BrC absorption by about 50% at 365nm. The mass absorption efficiencies measured for BrC in Beijing aerosol were converted to the imaginary refractive indices of BrC and subsequently used to compute BrC coating-induced enhancement of light absorption (E
abs ) by black carbon. Eabs attributed to lensing was reduced in the case of BrC coating relative to that caused by purely-scattering coating. However, this reduction was overwhelmed by the effect of BrC shell absorption, indicating that the overall effect of BrC coating was an increase in Eabs . Methanol extraction significantly reduced charring of OC during thermal-optical analysis, leading to a large increase in the measured elemental carbon (EC) mass and an apparent improvement in the consistency of EC measurements by different thermal-optical methods., (Copyright © 2017 Elsevier B.V. All rights reserved.)- Published
- 2017
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32. [Chemical Characteristics and Sources of Heavy Metals in Fine Particles in Beijing in 2011-2012].
- Author
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Zhou XM, Zheng NJ, Li YH, Duan JC, Tan JH, Zhang YX, He KB, and Ma YL
- Abstract
In order to investigate the chemical characteristics and sources of atmospheric heavy metals, PM
2.5 samples were collected every three days during the summer of 2011 and summer of 2012. The samples were analyzed for Li, V, Cr, Mn, Co, Cu, Zn, As, Se, Ti, Ga, Ni, Sr, Cd, In, Ba, Tl, Pb, Bi, and U by ICP-MS, with an emphasis on seven major heavy metal elements (Zn, Pb, Mn, Cu, As, V, and Cr). The concentrations of Zn, Pb, Mn, Cu, As, V, and Cr were (331.30±254.52), (212.64±182.06), (85.96±47.00), (45.19±27.74), (17.13±19.02), (4.92±3.38), and (9.04±7.84) ng·m-3 in PM2.5 in Beijing during the summer of 2011 and the summer of 2012. In the autumn and winter seasons, PM2.5 /heavy metal pollution is more severe than in spring and summer, which may be related to the increase in coal combustion used for heating in autumn and winter in Beijing. Haze pollution enhances the concentrations of seven heavy metals in PM2.5 in Beijing and the enhancement shows seasonal variations. The source analysis suggested that dust (including building dust and road dust) and coal combustion might be two most important sources of heavy metals in Beijing, and transport and other industrial sources cannot be ignored.- Published
- 2017
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33. [Seasonal Variation and Source Analysis of the Water-soluble Inorganic Ions in Fine Particulate Matter in Suzhou].
- Author
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Wang NF, Chen Y, Hao QJ, Wang HB, Yang FM, Zhao Q, Bo Y, He KB, and Yao YG
- Abstract
A total of 87 daily PM
2.5 samples were collected in the urban area of Suzhou city during 2015, representing spring, summer, autumn, winter, respectively. Mass concentration of PM2.5 was analyzed gravimetrically. Water-soluble inorganic ions, including F- , Cl- , NO3 - , SO4 2- , Na+ , NH4 + , K+ , Mg2+ and Ca2+ , were determined by ion chromatography. The average mass concentration of PM2.5 was (74.26±38.01) μg·m-3 . The seasonal variations of PM2.5 concentrations decreased in the order of winter > spring > autumn > summer. The average total mass concentrations of 9 ions was (43.95±23.60) μg·m-3 , and the order of concentration of ions was NO3 - > SO4 2- > NH4 + > Na+ > Cl- > K+ > Ca2+ > F- > Mg2+ . Seasonal variation of ion concentrations was significant, with the highest concentration observed in winter and the lowest in summer. The secondary inorganic species, including SO4 2- , NO3 - and NH4 + (SNA) were the major components of the water-soluble ions in PM2.5 . SNA's correlations with each other were significant. SO4 2- , NO3 - and NH4 + were probably in the form of NH4 NO3 and (NH4 )2 SO4 . The [NO3 - ]/[SO4 2- ] ratio approaching to 1 implied that mobile sources were as important as stationary sources. Ion balance calculations indicated strong correlations between anion and cation equivalents. The PM2.5 was acidic. Industrial emission, combustion process, secondary formation and fugitive dust were the major sources of the water-soluble ions in PM2.5. .- Published
- 2016
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34. [Pollution Characteristics of Non-methane Hydrocarbons During Winter and Summer in Foshan City].
- Author
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Zhou XM, Xiang P, Duan JC, He KB, Ma YL, Deng SX, Situ SP, and Tan JH
- Abstract
Thirty non-methane hydrocarbons(NMHCs) samples were collected and analyzed in Foshan City during winter 2014 and summer 2015. The concentrations of NMHCs during the sampling period were 122.30 μg·m
-3 and 56.22 μg·m-3 in winter and summer, respectively. The five highest concentration species of NMHCs in winter and summer were in the following order: toluene (25.12 μg·m-3 ), m/p -xylene (13.76 μg·m-3 ), propane (9.17 μg·m-3 ), ethylbenzene (7.25 μg·m-3 ), ethylene (6.77 μg·m-3 ) and toluene (6.18 μg·m-3 ), m/p -xylene (5.21 μg·m-3 ), o -xylene (4.15 μg·m-3 ), β -pinene(3.75 μg·m-3 ), propane (3.29 μg·m-3 ). Compared to 2008, the concentrations of NMHCs have dropped significantly. The proportions of aromatics, alkanes, alkenes and alkynes in NMHCs were 51.20%, 34.70%, 10.04%, 4.05% and 43.93%, 33.99%, 19.20%, 2.88% during winter and summer, respectively. The ratios of NMHCs/NOx were 0.90 and 1.88, indicating that the peak ozone concentrations in Foshan City were controlled by NMHCs during the sampling period, and the emissions of NMHCs should be further strengthened. The propylene equivalent concentration and ozone formation potential were 45.09 μg·m-3 and 40.64 μg·m-3 , 392.77 μg·m-3 and 207.77 μg·m-3 in winter and summer. The m/p -xylene; toluene and m/p -xylene; isoprene had a very important influence on ozone formation potential. The ratios of Benzene/Toluene were 0.15 and 0.20 indicated that industrial process was the main source of NMHCs in Foshan City. Relative to 2008, isopentane didn't belong to the highest concentration of five pollutants for Foshan's NMHCs in this research, indicating the measures to prevent volatile gasoline impact on the environmental quality have achieved remarkable results.- Published
- 2016
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35. High molecular weight organic compounds (HMW-OCs) in severe winter haze: Direct observation and insights on the formation mechanism.
- Author
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Duan FK, He KB, Ma YL, Ihozaki T, Kawasaki H, Arakawa R, Kitayama S, Tujimoto K, Huang T, Kimoto T, Furutani H, and Toyoda M
- Subjects
- Aerosols analysis, Atmosphere analysis, Environmental Monitoring, Hydrogen-Ion Concentration, Molecular Weight, Ozone chemistry, Seasons, Water chemistry, Air Pollutants chemistry, Organic Chemicals analysis, Particulate Matter chemistry
- Abstract
High molecular weight organic compounds (HMW-OCs), formed as secondary organic aerosols (SOA), have been reported in many laboratory studies. However, little evidence of HMW-OCs formation, in particular during winter season in the real atmosphere, has been reported. In January 2013, Beijing faced historically severe haze pollution, in which the hourly PM
2.5 concentration reached as high as 974 μg m-3 . Four typical haze events (HE1 to HE4) were identified, and HE2 (Jan. 9-16) was the most serious of these. Based on the hourly observed chemical composition of PM2.5 and the daily organic composition analyzed by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF-MS), we found that abundant ion peaks in m/z 200-850 appeared on heavy haze days, whereas these were negligible on a clear day, indicating the existence of HMW-OCs in the wintertime haze. A negative nonlinear correlation between HMW-OCs and O3 suggested that gas oxidation was not likely to be the dominant mechanism for HMW-OCs formation. During the heavy haze events, the relative humidity and mass ratio of H2 O/PM2.5 reached as high as 80% and 0.2, respectively. The high water content and its good positive correlation with HMW-OCs indicated that an aqueous-phase process may be a significant pathway in wintertime. The evidence that acidity was much higher during HE2 (0.37 μg m-3 ) than on other days, as well as its strong correlation with HMW-OCs, indicated that acid-catalyzed reactions likely resulted in HMW-OCs formation during the heavy winter haze in Beijing., (Copyright © 2016 Elsevier Ltd. All rights reserved.)- Published
- 2016
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36. Assessment of regional air quality by a concentration-dependent Pollution Permeation Index.
- Author
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Liang CS, Liu H, He KB, and Ma YL
- Abstract
Although air quality monitoring networks have been greatly improved, interpreting their expanding data in both simple and efficient ways remains challenging. Therefore, needed are new analytical methods. We developed such a method based on the comparison of pollutant concentrations between target and circum areas (circum comparison for short), and tested its applications by assessing the air pollution in Jing-Jin-Ji, Yangtze River Delta, Pearl River Delta and Cheng-Yu, China during 2015. We found the circum comparison can instantly judge whether a city is a pollution permeation donor or a pollution permeation receptor by a Pollution Permeation Index (PPI). Furthermore, a PPI-related estimated concentration (original concentration plus halved average concentration difference) can be used to identify some overestimations and underestimations. Besides, it can help explain pollution process (e.g., Beijing's PM
2.5 maybe largely promoted by non-local SO2 ) though not aiming at it. Moreover, it is applicable to any region, easy-to-handle, and able to boost more new analytical methods. These advantages, despite its disadvantages in considering the whole process jointly influenced by complex physical and chemical factors, demonstrate that the PPI based circum comparison can be efficiently used in assessing air pollution by yielding instructive results, without the absolute need for complex operations.- Published
- 2016
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37. [Pollutional Characteristics and Sources Analysis of Polycyclic Aromatic Hydrocarbons in Atmospheric Fine Particulate Matter in Lanzhou City].
- Author
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Li YH, Rao ZG, Tan JH, Duan JC, Ma YL, and He KB
- Abstract
Polycyclic aromatic hydrocarbons (PAHs) are a group of important toxic compounds. In order to detect the pollutional characteristics of atmospheric PAHs in Fine Particulate Matter (PM
2.5 ), a total of 60 PM2.5 samples were collected in Lanzhou City during the winter of 2012 and summer of 2013. The GC/MS measurement results of the samples demonstrated the averagely total mass concentrations of the most significant 16 homologues of PAHs were (191.79±88.29) ng·m-3 and (8.94±4.34) ng·m-3 in winter and summer respectively, indicating a higher pollution level in winter. In winter, the snowfall was the most important meteorological factor for the decrease of PAHs mass concentration in PM2.5 . The percentages of PAHs with 4 rings were the highest in both winter (51.40%) and summer (49.94%) in Lanzhou. The percentage of PAHs with 5-6 rings in summer (41.04%) was higher than that in winter (24.94%). However, the percentage of PAHs with 2-3 rings in summer (9.03%) was lower than that in winter (23.67%). Based on the analysis of characteristic ratios, we concluded that the PAHs in atmospheric PM2.5 in Lanzhou were mainly sourced from coal and vehicle emissions in winter, especially the diesel vehicles. The absolute contributions of all possible PAHs pollution sources were insignificant in summer, with relatively higher contribution from gasoline vehicles.- Published
- 2016
- Full Text
- View/download PDF
38. [Chemical Characteristics and Sources of Atmospheric Carbonyls During the 2014 Beijing APEC].
- Author
-
He XL, Tan JH, Guo SJ, Ma YL, and He KB
- Subjects
- Beijing, Coal, Particle Size, Particulate Matter analysis, Acetaldehyde analysis, Acetone analysis, Air Pollutants analysis, Environmental Monitoring, Formaldehyde analysis
- Abstract
Pollution characteristic and variation trend of atmospheric carbonyls were investigated in November during the 2014 Beijing APEC. Formaldehyde, acetaldehyde and acetone were the dominant carbonyls, accounting for 82.66% of total carbonyls, and especially, formaldehyde accounted for 40.12% of total carbonyls. Atmospheric concentrations of total carbonyls decreased by around 64.10% after the clean air policy was carried out during the Beijing APEC, and the variation trend of carbonyls showed a similar pattern to those of other pollutants like PM₂.₅ during the APEC. Strong correlations (R² of 0.67-0.98) were observed among formaldehyde, acetaldehyde, acetone and total carbonyls during and after the APEC, indicating that they had similar sources; however, poor correlations (R² of -0.11-0.42 and 0.16-0.94, respectively) were observed before the APEC, implying different emission sources for ambient carbonyls. The calculated ratios of C1/C2, C2/C3 and OC/EC indicated that both vehicles and coal emissions were responsible for atmospheric carbonyls before the APEC, and emissions from coal burning were the major contributor to atmospheric carbonyls during and after the APEC, especially after the APEC.
- Published
- 2016
39. Review on recent progress in observations, source identifications and countermeasures of PM2.5.
- Author
-
Liang CS, Duan FK, He KB, and Ma YL
- Subjects
- Aerosols analysis, Air Microbiology standards, Air Pollutants chemistry, Climate, Humans, Particle Size, Particulate Matter chemistry, Air Pollutants analysis, Air Pollution analysis, Air Pollution prevention & control, Environmental Monitoring methods, Particulate Matter analysis
- Abstract
Recently, PM2.5 (atmospheric fine particulate matter with aerodynamic diameter ≤ 2.5 μm) have received so much attention that the observations, source appointment and countermeasures of it have been widely studied due to its harmful impacts on visibility, mood (mental health), physical health, traffic safety, construction, economy and nature, as well as its complex interaction with climate. A review on the PM2.5 related research is necessary. We start with summary of chemical composition and characteristics of PM2.5 that contains both macro and micro observation results and analysis, wherein the temporal variability of concentrations of PM2.5 and major components in many recent reports is embraced. This is closely followed by an overview of source appointment, including the composition and sources of PM2.5 in different countries in the six inhabitable continents based on the best available results. Besides summarizing PM2.5 pollution countermeasures by policy, planning, technology and ideology, the World Air Day is proposed to be established to inspire and promote the crucial social action in energy-saving and emission-reduction. Some updated knowledge of the important topics (such as formation and evolution mechanisms of hazes, secondary aerosols, aerosol mass spectrometer, organic tracers, radiocarbon, emissions, solutions for air pollution problems, etc.) is also included in the present review by logically synthesizing the studies. In addition, the key research challenges and future directions are put forward. Despite our efforts, our understanding of the recent reported observations, source identifications and countermeasures of PM2.5 is limited, and subsequent efforts both of the authors and readers are needed., (Copyright © 2015 Elsevier Ltd. All rights reserved.)
- Published
- 2016
- Full Text
- View/download PDF
40. Uncertainties in observational data on organic aerosol: An annual perspective of sampling artifacts in Beijing, China.
- Author
-
Cheng Y and He KB
- Subjects
- Aerosols chemistry, Air Pollutants chemistry, Beijing, China, Uncertainty, Aerosols analysis, Air Pollutants analysis, Environmental Monitoring methods
- Abstract
Current understanding of organic aerosol (OA) is challenged by the large gap between simulation results and observational data. Based on six campaigns conducted in a representative mega city in China, this study provided an annual perspective of the uncertainties in observational OA data caused by sampling artifacts. Our results suggest that for the commonly-used sampling approach that involves collection of particles on a bare quartz filter, the positive artifact could result in a 20-40 % overestimation of OA concentrations. Based on an evaluation framework that includes four criteria, an activated carbon denuder was demonstrated to be able to effectively eliminate the positive artifact with a long useful time of at least one month, and hence it was recommended to be a good choice for routine measurement of carbonaceous aerosol., (Copyright © 2015 Elsevier Ltd. All rights reserved.)
- Published
- 2015
- Full Text
- View/download PDF
41. [Composition and Source Apportionments of Saccharides in Atmospheric Particulate Matter in Beijing].
- Author
-
Liang LL, Guenter E, Duan FK, Ma YL, Cheng Y, Du ZY, and He KB
- Subjects
- Aerosols, Beijing, Dust, Environmental Monitoring, Galactose analogs & derivatives, Glucose analogs & derivatives, Mannose analogs & derivatives, Seasons, Sugar Alcohols, Air Pollutants analysis, Carbohydrates analysis, Particulate Matter analysis
- Abstract
Based on the newly established high-performance anion exchange chromatography with pulsed amperometric detection (HPAEC-PAD), the saccharides in PM2.5 and PM10 in Beijing from 2011 - 2012 were quantified. Fourteen saccharides were synchronously detected in the aerosols samples in Beijing, which can be divided into three categories, i. e. anhydrosugar, sugar and sugar alcohol. Anhydrosugar, coming from biomass burning, include levoglucosan, mannosan and galactosan. Sugar and sugar alcohol, emitted by the primary biogenic emission, include glucose, fructose, trehalose, arabitol, mannitol, glycerol, threitol, 2-meythltrtols (2-methylthreitol and 2-methylerythrito), xylitol and inositol. The concentrations of monosaccharide anhydrides in summer and autumn were obviously higher than those in spring and winter, while the concentrations of sugar and sugar alcohol in winter were significantly lower than those in other seasons. The results of positive matrix factorization analysis suggested that saccharides compounds in atmospheric PM in Beijing can be derived from biomass burning, suspended soil or dust, isoprene SOA, as well as direct release of airborne fungal spores and pollen.
- Published
- 2015
42. Humidity plays an important role in the PM₂.₅ pollution in Beijing.
- Author
-
Cheng Y, He KB, Du ZY, Zheng M, Duan FK, and Ma YL
- Subjects
- Aerosols analysis, Air Pollution statistics & numerical data, Carbon analysis, China, Cities, Ions analysis, Nitrates analysis, Particle Size, Seasons, Water, Air Pollutants analysis, Environmental Monitoring, Humidity, Particulate Matter analysis
- Abstract
Heavily-polluted PM₂.₅ (fine particulate matter) episodes frequently impacting Beijing, especially during winter, have become a substantial concern. We found that during winter, the daily variation of PM2.5 in Beijing tracked the pattern of relative humidity (RH). With the increase of PM₂.₅ (or RH), water-soluble components (especially inorganic ions) became more abundant, and the water-soluble organic carbon to organic carbon ratios increased. The nitrate to sulfate ratios also exhibited dependence on RH, and were higher than those measured about a decade ago, consistent with the increasing trend of nitrogen oxides emissions. Surprisingly, the ratios of water-insoluble organic carbon to elemental carbon showed significant increase at high RH levels, presumably indicating the formation of secondary organic aerosol that is not soluble in water. In addition, humid winters were occasionally identified during 1996-2013 which are expected to be favorable for the formation of air pollution episodes with high PM₂.₅ concentrations., (Copyright © 2014 Elsevier Ltd. All rights reserved.)
- Published
- 2015
- Full Text
- View/download PDF
43. Source of atmospheric heavy metals in winter in Foshan, China.
- Author
-
Tan JH, Duan JC, Ma YL, Yang FM, Cheng Y, He KB, Yu YC, and Wang JW
- Subjects
- China, Cities, Particulate Matter analysis, Air Pollutants analysis, Atmosphere chemistry, Environmental Monitoring, Metals, Heavy analysis
- Abstract
Foshan is a ceramics manufacturing center in the world and the most polluted city in the Pearl River Delta (PRD) in southern China measured by the levels of atmospheric heavy metals. PM2.5 samples were collected in Foshan in winter 2008. Among the 22 elements and ions analyzed, 7 heavy metals (Zn, V, Mn, Cu, As, Cd and Pb) were studied in depth for their levels, spatiotemporal variations and sources. The ambient concentrations of the heavy metals were much higher than the reported average concentrations in China. The levels of Pb (675.7 ± 378.5 ng/m(3)), As (76.6 ± 49.1 ng/m(3)) and Cd (42.6 ± 45.2 ng/m(3)) exceeded the reference values of NAAQS (GB3095-2012) and the health guidelines of the World Health Organization. Generally, the levels of atmospheric heavy metals showed spatial distribution as: downtown site (CC, Chancheng District)>urban sites (NH and SD, Nanhai and Shunde Districts)>rural site (SS, Shanshui District). Two sources of heavy metals, the ceramic and aluminum industries, were identified during the sampling period. The large number of ceramic manufactures was responsible for the high levels of atmospheric Zn, Pb and As in Chancheng District. Transport from an aluminum industry park under light north-west winds contributed high levels of Cd to the SS site (Shanshui District). The average concentration of Cd under north-west wind was 220 ng/m(3), 20.5 times higher than those under other wind directions. The high daily maximum enrichment factors (EFs) of Cd, Pb, Zn, As and Cu at all four sites indicated extremely high contamination by local emissions. Back trajectory analysis showed that the heavy metals were also closely associated with the pathway of air mass. A positive matrix factorization (PMF) method was applied to determine the source apportionment of these heavy metals. Five factors (industry including the ceramic industry and coal combustion, vehicle emissions, dust, transportation and sea salt) were identified and industry was the most important source of atmospheric heavy metals. The present paper suggests a control policy on the four heavy metals Cd, Pb, Zn, and Cu, and suggests the inclusion of As in the ceramic industry emission standard in the future., (Copyright © 2014 Elsevier B.V. All rights reserved.)
- Published
- 2014
- Full Text
- View/download PDF
44. The characteristics of Beijing aerosol during two distinct episodes: impacts of biomass burning and fireworks.
- Author
-
Cheng Y, Engling G, He KB, Duan FK, Du ZY, Ma YL, Liang LL, Lu ZF, Liu JM, Zheng M, and Weber RJ
- Subjects
- Biomass, China, Fires, Nitrates analysis, Nitrogen Dioxide analysis, Seasons, Sulfates analysis, Sulfur Dioxide analysis, Aerosols analysis, Air Pollutants analysis, Environmental Monitoring, Explosive Agents
- Abstract
The chemical composition of Beijing aerosol was measured during summer and winter. Two distinct episodes were identified. Water-soluble potassium (K(+)) increased significantly during the firework episode in winter with an episode to non-episode ratio of 4.97, whereas the biomass burning (BB) episode in summer was characterized by high episode to non-episode ratios of levoglucosan (6.38) and K(+) (6.90). The BB and firework episodes had only a minor influence on the water-soluble OC (organic carbon) to OC ratio. Based on separate investigations of episode and non-episode periods, it was found that: (i) sulfate correlated strongly with both relative humidity and nitrate during the typical winter period presumably indicating the importance of the aqueous-phase oxidation of sulfur dioxide by nitrogen dioxide, (ii) oxalate and WSOC during both winter and summer in Beijing were mainly due to secondary formation, and (iii) high humidity can significantly enhance the formation potential of WSOC in winter., (Copyright © 2013 Elsevier Ltd. All rights reserved.)
- Published
- 2014
- Full Text
- View/download PDF
45. Ambient organic carbon to elemental carbon ratios: influence of the thermal-optical temperature protocol and implications.
- Author
-
Cheng Y, He KB, Duan FK, Du ZY, Zheng M, and Ma YL
- Subjects
- China, Aerosols chemistry, Carbon analysis, Environmental Monitoring methods, Models, Chemical, Particulate Matter analysis, Temperature
- Abstract
Ambient organic carbon (OC) to elemental carbon (EC) ratios are strongly associated with not only the radiative forcing due to aerosols but also the extent of secondary organic aerosol (SOA) formation. An inter-comparison study was conducted based on fine particulate matter samples collected during summer in Beijing to investigate the influence of the thermal-optical temperature protocol on the OC to EC ratio. Five temperature protocols were used such that the NIOSH (National Institute for Occupational Safety and Health) and EUSAAR (European Supersites for Atmospheric Aerosol Research) protocols were run by the Sunset carbon analyzer while the IMPROVE (the Interagency Monitoring of Protected Visual Environments network)-A protocol and two alternative protocols designed based on NIOSH and EUSAAR were run by the DRI analyzer. The optical attenuation measured by the Sunset carbon analyzer was more easily biased by the shadowing effect, whereas total carbon agreed well between the Sunset and DRI analyzers. The EC(IMPROVE-A) (EC measured by the IMPROVE-A protocol; similar hereinafter) to EC(NIOSH) ratio and the EC(IMPROVE-A) to EC(EUSAAR) ratio averaged 1.36 ± 0.21 and 0.91 ± 0.10, respectively, both of which exhibited little dependence on the biomass burning contribution. Though the temperature protocol had substantial influence on the OC to EC ratio, the contributions of secondary organic carbon (SOC) to OC, which were predicted by the EC-tracer method, did not differ significantly among the five protocols. Moreover, the SOC contributions obtained in this study were comparable with previous results based on field observation (typically between 45 and 65%), but were substantially higher than the estimation provided by an air quality model (only 18%). The comparison of SOC and WSOC suggests that when using the transmittance charring correction, all of the three common protocols (i.e., IMPROVE-A, NIOSH and EUSAAR) could be reliable for the estimation of SOC by the EC-tracer method., (© 2013 Elsevier B.V. All rights reserved.)
- Published
- 2014
- Full Text
- View/download PDF
46. [Preparation of Kushen-Dilong nanoemulsion gel and transdermal characterization in vitro].
- Author
-
He KB, Wang YZ, Feng AL, Duan FP, Li CX, and Sun XY
- Subjects
- Animals, Chemistry, Pharmaceutical, Drug Carriers chemistry, Emulsions, Gels, Rats, Rats, Sprague-Dawley, Drugs, Chinese Herbal chemistry, Drugs, Chinese Herbal metabolism, Nanostructures chemistry, Skin metabolism, Skin Absorption
- Abstract
Objective: To prepare Kushen-Dilong nanoemulsion and nanoemuls-ion gel, and investigate its content, physical and chemical properties. Their transdermal properties in vitro were studied as well., Method: IPM acted as oil phase, EL35 as surfactant, EtOH as cosurfactant, Pheretima aqueous solution was added dropwise to the oil phase to prepare Kushen-Dilong nanoemulsion at room temperature using magnetic stirring. HPLC was used to determine the content of matrine and oxymatrine in the nanoemulsion. Transmission electron microscopy and laser particle size analyzer was used to determine the shape and size of the nanoemulsion. NP700 was used as substrate to prepare Kushen-Dilong nanoemulsion gel. Franz diffusion cell was used for the nanoemulsion and gel transdermal characteristics in vitro., Result: The Kushen-Dilong nanoemulsion was O/W nanoemulsion, its uniform particle size was 20.6 nm with roundness appearance and stable content. The steady-state permeation rate of Kushen-Dilong nanoemulsion, nanoemulsion gel, saturated aqueous solution, hydro gel were 0.1484, 0.1183, 0.0306, 0.0321 mg x cm(-2) x h(-1), respectively., Conclusion: The 24 h cumulative infiltration and infiltration rate of Kushen-Dilong nanoemulsion and nanoemulsion gel were better than the saturated aqueous solution and hydro gel, which could provide a new dosage form for Kushen-Dilong transdermal drug delivery.
- Published
- 2013
47. [Pollution characteristics of organic acids in atmospheric particles during haze periods in autumn in Guangzhou].
- Author
-
Tan JH, Zhao JP, Duan JC, Ma YL, He KB, and Yang FM
- Subjects
- Air Pollutants analysis, Atmosphere, China, Environmental Monitoring methods, Organic Chemicals analysis, Particle Size, Seasons, Air Pollutants chemistry, Air Pollution analysis, Dicarboxylic Acids analysis, Fatty Acids analysis
- Abstract
Total suspended particles (TSP), collected during a typical haze period in Guangzhou, were analyzed for the fatty acids (C12-C30) and low molecular weight dicarboxylic acids (C3-C9) using gas chromatography/mass spectrometry (GC/MS). The results showed that the concentration of total fatty and carboxylic acids was pretty high during the haze episode. The ratios of fatty acids and carboxylic acids in haze to those in normal days were 1.9 and 2.5, respectively. During the episode of the increasing pollution, the fatty acids and carboxylic acids at night (653 ng x m(-3)) was higher than that (487 ng x m(-3)) in days. After that, the level of fatty acids and carboxylic acids in days (412 ng x m(-3)) was higher than that (336 ng x m(-3)) at night. In general, the time-series of fatty acids and carboxylic acids was similar to that of the air particle and carbonaceous species, however, the trend of the ratio of fatty acids and carboxylic acids to organic carbon was opposite to that of air particle and carbonaceous species. This ratio decreased with the increase of the concentration of air particle and after the night of 27th, the ratio increased with the decrease in the concentration of air particle. The results showed that haze pollution had a significant inhibitory effect on the enrichment of fatty and carboxylic acids. Based on the ratio of malonate to succinate (C3/C4), it could be found that primary sources contribute more to the atmospheric fatty and carboxylic acids during the autumn haze pollution periods in Guangzhou.
- Published
- 2013
48. [Characteristics of volatile organic compounds during haze episode in Foshan city].
- Author
-
Ma YL, Tan JH, He KB, Cheng Y, Yang FM, Yu YC, Tan YH, and Wang JW
- Subjects
- Benzene analysis, China, Cities, Pentanes analysis, Toluene analysis, Air Pollutants analysis, Environmental Monitoring methods, Volatile Organic Compounds analysis
- Abstract
Volatile Organic Compounds (VOCs) in Foshan City were investigated in December 6 to 30 2008. The concentrations of VOCs in haze days were significantly higher than those in no-haze days. Toluene (68.93 microg x m(-3) +/- 37.78 microg x m(-3)) was the most abundant compound of VOCs in haze days and i-pentane (20.59 microg x m(-3) +/- 14.28 microg x m(-3)) was the most abundant compound in no-haze days, respectively. During haze episodes, the diurnal variations of alkanes and alkynes were not significantly; however, alkenes and aromatic hydrocarbon decreased significantly at noon. During no-haze episodes, the diurnal variations patterns of VOCs were stable. Propylene-equivalent concentrations in haze days were significantly higher than those in no-haze days, toluene was the most abundant compound of Propylene-equivalent concentration in haze days, followed by propene and ethene; propene was the most abundant compound in no-haze days, followed by ethene and 1-butene. High concentration of benzene (18.1 microg x m(-3)) in haze days posed a great health threat to public in Foshan city. Both diurnal variation of VOCs and measured ratios indicated vehicular emissions acted as the main sources of most VOCs and other sources like solvent application also contributed to VOCs (benzene and toluene).
- Published
- 2011
49. Intercomparison of thermal-optical methods for the determination of organic and elemental carbon: influences of aerosol composition and implications.
- Author
-
Cheng Y, Duan FK, He KB, Zheng M, Du ZY, Ma YL, and Tan JH
- Subjects
- China, Environmental Monitoring, Aerosols analysis, Carbon analysis, Organic Chemicals analysis
- Abstract
An intercomparison of organic carbon (OC) and elemental carbon (EC) measurements was conducted based on ambient aerosol samples collected during four seasons in Beijing, China. Dependence of OC and EC values on the temperature protocol and the charring correction method is presented and influences of aerosol composition are investigated. EC was found to decrease with the peak inert mode temperature (T(peak)) such that EC determined by the IMPROVE (the Interagency Monitoring of Protected Visual Environments)-A protocol (T(peak) was 580 °C) was 2.85 ± 1.31 and 3.83 ± 2.58 times that measured by an alternative protocol with a T(peak) of 850 °C when using the transmittance and reflectance correction, respectively. It was also found that reflectance correction tends to classify more carbon as EC compared with transmittance; results from the IMPROVE-A protocol showed that the ratio of EC defined by reflectance correction (EC(R)) to that based on transmittance (EC(T)) averaged 1.50 ± 0.42. Moreover, it was demonstrated that emissions from biomass burning would increase the discrepancy between EC values determined by different temperature protocols. On the other hand, the discrepancy between EC(R) and EC(T) was strongly associated with secondary organic aerosol (SOA) which was shown to be an important source of the organics that pyrolyze during the inert mode of thermal-optical analysis.
- Published
- 2011
- Full Text
- View/download PDF
50. [Removal of gaseous elemental mercury over cerium doped low vanadium loading V2O5-WO3/TiO2 in simulated coal-fired flue gas].
- Author
-
Wan Q, Duan L, He KB, Chen L, and Li JH
- Subjects
- Air Pollutants isolation & purification, Air Pollution prevention & control, Catalysis, China, Coal, Gases, Power Plants, Vanadium chemistry, Cerium chemistry, Mercury isolation & purification, Oxides chemistry, Titanium chemistry, Tungsten chemistry, Vanadium Compounds chemistry
- Abstract
This paper discussed a recent study of mercury removal by gaseous hydrogen chloride over novel Ce doped low vanadium V2O5-WO3/TiO2 catalysts under a bench scale condition. The performances on Hg(0) removal over the catalyst were tested in simulated flue gas with 80-100 microg x m(-3) Hg(0), 8% O2, 10 x10(-6) HCl, 8% H2O, 800 x10(-6) SO2 and balanced with N2. Results showed that about 95% of Hg(0) could be removed. According to the characterization results, BET surface areas had not significant influence on catalytic performance. XPS results indicated that Ce4+ oxide was a mainly form in the catalysts surface, which was beneficial for Hg(0) removal reactions. Water vapor slightly inhibited Hg(0) removal efficiency, due to the competitive adsorption, however, SO2 promoted the oxidation reactions, resulting in higher removal efficiencies.
- Published
- 2011
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