Article

The characteristics of PM2.5 in Beijing, China

Authors:
  • Chongqing Institute of Green and Intelligent Technology, Chinese Academy of Sciences
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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 μg/m3, 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.

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... Not only does it inform as to the predominant size of the PM, but could be an indication if the PM is predominantly anthropogenic (higher ratio) or naturally occurring airborne particles (lower ratio) [8]. In addition, the PM 2.5 /PM 10 ratio has been shown to provide useful information on local dusty processes in the atmosphere and types of PM pollution in a particular region [9][10][11][12][13][14]. Apart from mass concentrations, the PM collected from industrial city areas is enriched with trace elements (TEs) [15][16][17]. ...
... Figure 3 shows that the average PM2.5/PM10 ratio was 0.85, and the minimum and maximum ratio 0.70 and 0.95, respectively. The average PM2.5/PM10 ratio obtained in Chelyabinsk was generally higher than reported for Asia (0.5) [9,14,49], China (0.62) [10][11][12], and in 20 European Cities (0.6) ( [50] and references therein). Seasonal variation (often with a diurnal distribution) is also observed and differs according to meteorological conditions. ...
... On the other hand, the ratio at Station 3 did not stay constant and did not display the typical seasonal variation. The average PM 2.5 /PM 10 ratio obtained in Chelyabinsk was generally higher than reported for Asia (0.5) [9,14,49], China (0.62) [10][11][12], and in 20 European Cities (0.6) ( [50] and references therein). Seasonal variation (often with a diurnal distribution) is also observed and differs according to meteorological conditions. ...
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Air pollution impacts all populations globally, indiscriminately and has site-specific variation and characteristics. Airborne particulate matter (PM) levels were monitored in a typical industrial Russian city, Chelyabinsk in three destinations, one characterized by high traffic volumes and two by industrial zone emissions. The mass concentration and trace metal content of PM2.5 and PM10 were obtained from samples collected during four distinct seasons of 2020. The mean 24-h PM10 ranged between 6 and 64 μg/m3. 24-h PM2.5 levels were reported from 5 to 56 μg/m3. About half of the 24-h PM10 and most of the PM2.5 values in Chelyabinsk were higher than the WHO recommendations. The mean PM2.5/PM10 ratio was measured at 0.85, indicative of anthropogenic input. To evaluate the Al, Fe, As, Cd, Co, Cr, Cu, Mn, Ni, Pb, and Zn concentration in PM2.5 and PM10, inductively coupled plasma mass spectrometry (ICP-MS) was used. Fe (337–732 ng/m3) was the most abundant component in PM2.5 and PM10 samples while Zn (77–206 ng/m3), Mn (10–96 ng/m3), and Pb (11–41 ng/m3) had the highest concentrations among trace elements. Total non-carcinogenic risks for children were found higher than 1, indicating possible health hazards. This study also presents that the carcinogenic risk for As, Cr, Co, Cd, Ni, and Pb were observed higher than the acceptable limit (1 × 10−6).
... In recent years, many studies have been conducted to investigate the formation mechanisms of heavy haze. PM 2.5 concentration in the atmosphere is influenced by a variety of factors, such as pollutant emissions, regional transportation, aerosol physicochemical processes, gas-particle conversion, and meteorological conditions [4][5][6][7]. Ye et al. [8] concluded that there was a significant relationship between daily PM 2.5 concentration and meteorological factors, including temperature (T), relative humidity (RH), wind speed (WS), and wind direction (WD), and they suggested that an increase in RH could promote the growth of PM 2.5 . Meanwhile, PM 2.5 was negatively correlated with WS; that is, with increases in WS, PM 2.5 showed a decreasing trend, which was attributed to a high WS helping to disperse PM 2.5 [8]. ...
... Compared to other water-soluble ions, the concentration of NO 3 − was the highest in Shanghai in 2018, with an annual mean concentration of 10.7 ± 12.1 µg m −3 , followed by SO 4 2− (7. ...
... . This concentration differs from that of Beijing, where Zhang et al. [18] found that the largest concentration was SO 4 2 ...
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In order to explore the mechanism of haze formation, the meteorological effect and chemical reaction process of the explosive growth (EG) of PM2.5 were studied. In this study, the level of PM2.5, water-soluble inorganic ions, carbonaceous aerosols, gaseous precursors, and meteorological factors were analyzed in Shanghai in 2018. The EG event is defined by a net increase of PM2.5 mass concentration greater than or equal to 100 μg m−3 within 3, 6, or 9 h. The results showed that the annual average PM2.5 concentration in Shanghai in 2018 was 43.2 μg m−3, and secondary inorganic aerosols and organic matter (OM) accounted for 55.8% and 20.1% of PM2.5, respectively. The increase and decrease in the contributions of sulfate, nitrate, ammonium (SNA), and elemental carbon (EC) to PM2.5 from clean days to EG, respectively, indicated a strong, secondary transformation during EG. Three EG episodes (Ep) were studied in detail, and the PM2.5 concentration in Ep3 was highest (135.7 μg m−3), followed by Ep2 (129.6 μg m−3), and Ep1 (82.3 μg m−3). The EG was driven by stagnant conditions and chemical reactions (heterogeneous and gas-phase oxidation reactions). This study improves our understanding of the mechanism of haze pollution and provides a scientific basis for air pollution control in Shanghai.
... Generally, there are two main factors contributing to air pollution: anthropo activities and natural events. Anthropogenic activities that release emissions to the a phere include industrial expansion [24], coal or plant burning [25], vehicle consum [26], and mineral particles [27]. Most of the air contamination in natural events is ch terized by visible changes, such as hazy weather and sand storms from the Gobi d [28]. ...
... Generally, there are two main factors contributing to air pollution: anthropogenic activities and natural events. Anthropogenic activities that release emissions to the atmosphere include industrial expansion [24], coal or plant burning [25], vehicle consumption [26], and mineral particles [27]. Most of the air contamination in natural events is characterized by visible changes, such as hazy weather and sand storms from the Gobi desert [28]. ...
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Fine dust generated by particulate matter (PM) pollution is a serious ecological issue in industrialized countries and causes disorders of the respiratory system and skin in humans. In the previous study, Sargassum fusiforme was treated with citric acid to remove heavy metals. In this study, the transfer of PM-mediated inflammatory responses through the skin to macrophages was evaluated. Moreover, the anti-adhesive effects of calcium alginate isolated from S. fusiforme (SFCA) against PM-induced inflammation were investigated. The structures of processing and unprocessing SFCA were then analyzed by Fourier-transform infrared spectroscopy (FT-IR), revealing minimal change after acid-processing. SFCA had protective effects both in PM-stimulated HaCaT keratinocytes and RAW 264.7 macrophages. In cellular environments, it was found that SFCA attenuated signal protein expressions such as inducible nitric oxide synthase (iNOS), cyclooxygenase (COX)-2, prostaglandin E2 (PGE2), and pro-inflammatory cytokines. Furthermore, macrophages were added to the culture medium of PM-stimulated keratinocytes to induce inflammation. SFCA was observed to significantly inhibit inflammatory responses; additionally, SFCA showed an in vivo anti-adhesive effect in zebrafish embryos.
... According to statistics [2], since 2000, China's DH area has increased by about 16.67% annually on average, and the total DH area has reached 11 billion m 2 by the end of 2019. The Combined Heating and Power (CHP) or fossil fuel boilers are usually adopted for the DH as heat sources, while fossil fuel leads to severe environment problems [3] and the carbon emission [4]. The long-distance district heating pipeline (LDHP) system, which can transport the waste heat, and renewable heat from the exurban to the urban area, has obvious advantages in reducing carbon emissions and improving urban air quality [5][6][7]. ...
... where Q P2 (m 3 ...
Article
The long-distance district heating pipeline (LDHP) system can deliver waste heat from suburban areas to urban areas. Valve-induced hydraulic oscillation caused by valve failure will lead to large fluctuations of pressure, which may also result in pipeline rupture of the LDHP system. Fast and accurate detection of the faulty valve is a necessary measure for efficient repair and adjustment of the LDHP system. In this paper, the hydraulic transient model of the LDHP system based on the distributed parameter method is combined with the Particle Swarm Optimization algorithm to realize fast and accurate detection of the location and status of faulty valve, by recognizing the faulty valve-induced hydraulic oscillation in the LDHP. The effectiveness of the detection algorithm is verified by numerical simulation of a 20 km LDHP system, and the effects of instrumental error and sampling period on the robustness of the algorithm are investigated. Results show that when the sampling period is less than 10 s, the relative errors of the detected location and opening of the faulty valve are less than 8% and 0.1%, respectively. Therefore, the faulty valve-induced hydraulic oscillation in the LDHP can be effectively detected based on the method proposed in this paper.
... According to PM 2.5 observations elsewhere in the region (mostly outside of Jordan; see Table 1), the OC and EC concentrations reported herein are comparable. A greater interest might be the extremely high OC concentrations in Beijing (29.1 µg m -3 ) and Tehran (15.35 ± 6.05 µg m -3 ) with corresponding PM 2.5 concentrations of 115 µg m -3 and 41.2 µg m -3 , respectively [61,62]. As for PM 10 observations elsewhere (Table 2), the OC concentrations reported here are generally lower than those reported in other regions in the world. ...
... According to PM2.5 observations elsewhere in the region (mostly outside of Jordan; see Table 1), the OC and EC concentrations reported herein are comparable. A greater interest might be the extremely high OC concentrations in Beijing (29.1 µg m -3 ) and Tehran (15.35 ± 6.05 µg m -3 ) with corresponding PM2.5 concentrations of 115 µg m -3 and 41.2 µg m -3 , respectively [61,62]. As for PM10 observations elsewhere (Table 2), the OC concentrations reported here are generally lower than those reported in other regions in the world. ...
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The Mediterranean region is an important area for air pollution as it is the crossroads between three continents; therefore, the concentrations of atmospheric aerosol particles are influenced by emissions from Africa, Asia, and Europe. Here we concentrate on an eleven-month time series of the ambient concentration of organic carbon (OC) and elemental carbon (EC) between May 2018–March 2019 in Amman, Jordan. Such a dataset is unique in Jordan. The results show that the OC and EC annual mean concentrations in PM2.5 samples were 5.9 ± 2.8 µg m–3 and 1.7 ± 1.1 µg m–3, respectively. It was found that the majority of OC and EC concentrations were within the fine particle fraction (PM2.5). During sand and dust storm (SDS) episodes OC and EC concentrations were higher than the annual means; the mean values during these periods were about 9.6 ± 3.5 µg m–3 and 2.5 ± 1.2 µg m–3 in the PM2.5 samples. Based on this, the SDS episodes were identified to be responsible for an increased carbonaceous aerosol content as well as PM2.5 and PM10 content, which may have direct implications on human health. This study encourages us to perform more extensive measurements during a longer time period and to include an advanced chemical and physical characterization for urban aerosols in the urban atmosphere of Amman, which can be representative of other urban areas in the region.
... Over the last several decades, there has been increasing concern regarding PM 2.5 (i.e., particles with an aerodynamic diameter of 2.5 μm or less) pollutants because of their adverse effects on human health (Chameides et al., 1999), the formation of haze (Wang et al., 2014a(Wang et al., , 2014bZhang et al., 2015;Yang et al., 2015;Jiang et al., 2015) and the atmosphere's radiative balance (Charlson et al., 1987). PM 2.5 is a complex mixture of elemental carbon, organic carbon (OC), ammonium, nitrates, sulfates, mineral dust, trace elements, and water (He et al., 2001;Huang et al., 2014;Chen et al., 2019a). It originates from both natural (e.g., dust storms and outdoor biomass burning) and anthropogenic sources (e.g., industry, vehicle emissions, residences, and other human activities) (Yao et al., 2016), and includes both primary and secondary particle species (Tao et al., 2014). ...
... Comparison of Fig. 5 and Table 3 indicates that the years with higher positive PM 2.5 anomalies often correspond to lower PBLH anomalies, and vice versa again for 2003, when the PM 2.5 concentration was the highest, as an example, large negative PBLH anomalies were found in most of the study area. A similar situation occurred in 2001. In contrast, 2002, 2007and 2005 are the three years with relatively lower PM 2.5 concentrations compared to the 15-year average (larger negative anomaly, as shown in Table 3), and there were generally positive anomalies of PBLH in these years in Beijing and its adjacent regions (as shown in Fig. 5). ...
Article
Particles with an aerodynamic diameter of 2.5 μm or less (PM2.5) in the ambient air are affected not only by local emissions but also by regional transport of the pollutant and its precursors, which may vary considerably under different meteorological conditions. This issue has been extensively investigated in terms of the contribution of regional transport to PM2.5 at different seasons in a specific year. However, the literature yields conflicting results, and the extent to which inter-annual meteorological variation affects the contribution of regional transport is not fully understood, especially in the long-term. Therefore, in this study, the WRF/CMAQ model was employed to investigate inter-annual variations in the contribution of regional transport to PM2.5 concentration in Beijing from 2001 to 2015. The emission inventory and model configurations were kept the same for the 15-year simulation to highlight the impact of inter-annual meteorological variations. The major findings can be summarized as follows: (1) inter-annual meteorological variation has an impact on both the PM2.5 concentration in Beijing and the contribution of regional transport; (2) the annual average PM2.5 concentrations in Beijing varied during the study period, from 75.3 μg/m³ in 2002 to 108.1 μg/m³ in 2013; (3) the years with high annual anomalies of PM2.5 was found during periods of low wind speed, high relative humidity, and low planetary boundary layer (PBL) height; (4) the annual variability was relatively small compared to the changes in seasonal because some seasons in a year are higher than their historical average values, and some are lower, which often negate each other, making the annual average close to the historical average; (5) the contribution of regional transport averaged 44.5% and ranged from 40.7% in 2007 to 48.5% in 2001. On a seasonal basis, the inter-annual fluctuation was more significant, with fluctuation rates of 43.0%, 25.5%, 25.0%, and 20.6% in winter, fall, spring, and summer, respectively; and (6) in general, there is a good positive correlation between the regional contribution and PM2.5 concentration in Beijing. Specifically, when the regional transport contribution is large, the PM2.5 concentration tends to be higher. This is especially true during years when both the concentration and contribution deviate significantly from the historical average.
... The number of days with PM 2.5 (particles less than or equal to 2.5 microns) as the primary pollutant accounted for 60.0% of the days with severe or higher pollution. The chemical composition of PM 2.5 is complex [2], and its scattering and extinction effects will cause a decrease in atmospheric visibility [3], resulting in haze weather, which has a severe impact on the health of residents [4]. Dockery [5] studied the effect of air pollution on children's health in six cities. ...
... The data was by Matlab R2019b (MathWorks, Natick, MA, USA). If the PM2.5 and PM10 c data of Equation (1) are satisfied, the average value will be used for replace temperature and humidity data, the change of the values is more stable, so value will still be used for replacement of the data of Equation (2). ...
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Accurate prediction of PM2.5 concentration is one of the key tasks of air pollution assessment, early warning, and treatment. In this paper, four monitoring sites were arranged in Jiangbei New District of Nanjing City, China. The environmental parameters such as PM2.5/PM10 concentration, temperature, and humidity were monitored from January to February 2020. A gated recurrent unit (GRU) network based on the PM2.5 concentration prediction model was established to predict PM2.5 concentration. The mean relative error (MRE), root mean square error (RMSE), and Pearson correlation coefficient were selected as the evaluation criteria for the accuracy of the GRU model. The data set was divided into a training set, a test set and a validation set at a ratio of 7:2:1, and the GRU model was used to predict the hourly value of PM2.5 concentration in the next week. The prediction results show that the Pearson correlation coefficients between the predicted values and the monitored values of the four monitoring sites have reached more than 0.9, reflecting a strong correlation. The relative average errors are around 10%. The GRU model prediction of NJAU (Nanjing Agricultural University)-Pukou Campus Site is the most accurate, and the correlation coefficient, MRE, and RMSE are 0.970, 7.85%, and 9.6049, respectively, reflecting the good prediction performance of the model. Therefore, this research supports the prediction of air quality in different cities and regions, so people can take protective measures in advance and reduce the damage caused by air pollution to human bodies.
... Carbonaceous aerosols, often one of the most abundant components (20 %-80 %) in atmospheric aerosol particles, have a crucial impact on the global climate, air quality, and human health (He et al., 2001;Huang et al., 2014;Jimenez et al., 2009;Song et al., 2007;Zhou et al., 2018). The total content of carbonaceous aerosols (i.e., total carbon, TC) can be divided into organic carbon (OC) and elemental carbon (EC) according to their physical, chemical, and optical properties. ...
Article
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Carbonaceous aerosol is a dominant component of fine particles in Beijing. However, it is challenging to apportion its sources. Here, we applied a newly developed method which combined radiocarbon (14C) with organic tracers to apportion the sources of fine carbonaceous particles at an urban (IAP) and a rural (PG) site of Beijing. PM2.5 filter samples (24 h) were collected at both sites from 10 November to 11 December 2016 and from 22 May to 24 June 2017. 14C was determined in 25 aerosol samples (13 at IAP and 12 at PG) representing low pollution to haze conditions. Biomass burning tracers (levoglucosan, mannosan, and galactosan) in the samples were also determined using gas chromatography–mass spectrometry (GC-MS). Higher contributions of fossil-derived OC (OCf) were found at the urban site. The OCf / OC ratio decreased in the summer samples (IAP: 67.8 ± 4.0 % in winter and 54.2 ± 11.7 % in summer; PG: 59.3 ± 5.7 % in winter and 50.0 ± 9.0 % in summer) due to less consumption of coal in the warm season. A novel extended Gelencsér (EG) method incorporating the 14C and organic tracer data was developed to estimate the fossil and non-fossil sources of primary and secondary OC (POC and SOC). It showed that fossil-derived POC was the largest contributor to OC (35.8 ± 10.5 % and 34.1 ± 8.7 % in wintertime for IAP and PG, 28.9 ± 7.4 % and 29.1 ± 9.4 % in summer), regardless of season. SOC contributed 50.0 ± 12.3 % and 47.2 ± 15.5 % at IAP and 42.0 ± 11.7 % and 43.0 ± 13.4 % at PG in the winter and summer sampling periods, respectively, within which the fossil-derived SOC was predominant and contributed more in winter. The non-fossil fractions of SOC increased in summer due to a larger biogenic component. Concentrations of biomass burning OC (OCbb) are resolved by the extended Gelencsér method, with average contributions (to total OC) of 10.6 ± 1.7 % and 10.4 ± 1.5 % in winter at IAP and PG and 6.5 ± 5.2 % and 17.9 ± 3.5 % in summer, respectively. Correlations of water-insoluble OC (WINSOC) and water-soluble OC (WSOC) with POC and SOC showed that although WINSOC was the major contributor to POC, a non-negligible fraction of WINSOC was found in SOC for both fossil and non-fossil sources, especially during winter. In summer, a greater proportion of WSOC from non-fossil sources was found in SOC. Comparisons of the source apportionment results with those obtained from a chemical mass balance model were generally good, except for the cooking aerosol.
... Taking the PM2.5 air quality level as an example, the folded IBNM function f p based on the PM2.5 level is constructed. PM2.5 refers to particulate matters in the atmosphere whose diameter is less than or equals 2.5 microns, also known as particulate matter that could enter the lung (He et al. 2001). Various states have various standards for PM2.5. ...
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In the face of interval sensitive data, aiming at the disadvantages of rationality and adaptability of linear dimensionless method, as well as the complexity of constructing polyline and curve dimensionless method, this paper proposes an Interval-based Non-dimensionalization Method (IBNM). Assuming that the data can be divided into n levels within its domain, IBNM divides n intervals based on these n grades. N + 1 connection points were set by taking the critical points between the intervals as abscissa and the sequence values corresponding to the n grades of the critical points as ordinate. Then, the dimensionless transformation function IBNM is constructed by connecting adjacent connection points according to fuzzy mathematics theory. If the connection mode of IBNM is simple piecewise linear function, then called it polyline IBNM. Accordingly, if the connection mode adopts exponential function, logarithmic function and other curve functions, it is called curve IBNM. IBNM is scientific, reasonable, simple and practical. This paper takes PM2.5 air quality grade prediction as an example and constructs four kinds of air quality grade prediction models. A variety of traditional dimensionless methods, polyline IBNM and curve IBNM were used to process the data, respectively, and were applied to these prediction models. The results show that the effect of polyline IBNM and curve IBNM is better than that of traditional non-dimensionalization methods.
... Those pollutants can be used as key indicators in measuring the AQI of a region. One of the most commonly used in the literature is PM2.5, i.e., the particulate matter with a diameter less than 2.5µ [4][5][6][7]. ...
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Air is a necessary element for all living beings. The quality of air could affect the well-being of the people, and therefore, it is important to make sure that the air quality could be measured properly. One standard measurement of air quality is the Air Quality Index (AQI). In this study, the Jakarta City AQI, as one of the cities that suffer from bad air quality due to several factors, will be predicted using two modified hybrid prediction methods, namely the B-WEMA and the H-WEMA methods. The comparative results in two collected datasets, i.e., the Central Jakarta and the South Jakarta AQIs, showed that B-WEMA excels H-WEMA in predicting the air quality.
... In early 1995, Degaetano et al. [27] believed that fog and haze might affect the accuracy of daily total solar radiation model. In the study of Sun et al. [28], meteorological data, solar radiation, and air pollution index data from three sites having different air pollution index conditions were used to develop random forest models. The results show that the performance of random forest models with air pollution index data is better than that of the empirical methodologies, generating 9.1e17.0% ...
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Air pollution has a significant weakening effect on solar radiation. Therefore, it is important for the development and utilization of solar energy to establish a solar radiation model under the influence of fog and haze. Based on the analysis of existing layer-by-layer weakening solar radiation models, the discontinuous meteorological data provided by MODIS satellite are replaced by continuous measured data from meteorological stations. The beam solar radiation model and diffuse solar radiation model are modified by using relative humidity (φ) and air quality index (AQI). The results show that the correction effects of these modified models are better. The R value of beam solar radiation models have increased by 5.74%, the R value of diffuse solar radiation models have increased by 41.27%, and other statistical parameters (RSE, RMSE and NSE) have also been improved to a certain extent. The calculated value of the modified models is closer to the measured data. In addition, the order of correction parameters also has an effect on the results. The research shows that the best correction effect is to use relative humidity first and then AQI. According to this method, the layer-by-layer weakening solar radiation models can be more accurate and reliable.
... Some filters used to collect ambient aerosols include quartz, Teflon, polycarbonate, polyester, nylon, silver (Ag) foil, and aluminum (Al) foil [6,[97][98][99]. A study showed that Ag foil can act as a SERS substrate by producing intense Raman peaks for species such as soot (1350 cm −1 and 1589 cm −1 ), nitrates (1045 cm −1 ), and sulfates (978 cm −1 ) in samples [100]. ...
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Atmospheric aerosols, produced as a consequence of different anthropogenic and natural processes, impart significant control over the global energy budget, climate, and human–environmental health. Their size varies across the nano–micrometer scale. Based on their origin, they may be classified into primary or secondary aerosols. Biomass burning, incomplete combustion of fossil fuels, volcanic eruptions, and traffic-related and wind-driven suspensions contribute to primary aerosol emissions. In contrast, gas-to-particle conversion within the atmosphere leads to secondary particle production. The study of atmospheric aerosols is vital to the field of atmospheric research. The dynamic nature (highly variable concentration composition and size with space and time) of aerosols makes them difficult to investigate. Today, aerosol research involves the application of various spectrometric and spectroscopic techniques. The single-particle analysis of aerosols is yet a challenge. In this review, the merits and demerits of various offline and online techniques used for aerosol research are discussed in a nutshell. Mass spectrometric techniques fail in distinguishing certain species. However, Raman spectroscopy’s emergence for the compositional analysis of aerosols resolves most of the present characterization challenges. This review focuses on Raman spectroscopy applications, the merits of this technique, and its immense scope for the measurement of various types of aerosols and their properties. Surface-enhanced Raman spectroscopy (SERS) has an advantage over conventional micro-Raman spectroscopy (MRS). The review depicts the dominance of SERS, specifically in the context of the measurement of ambient atmospheric aerosols. This review discusses two important components, namely laboratory simulation and ambient aerosol studies.
... Studies on fine particulate matter (PM 2.5 ) in China started in the early 2000s (He et al., 2001), shortly after the establishment of the first National Ambient Air Quality Standard (NAAQS) for PM 2.5 by the US Environmental Protection Agency (EPA). The investigations were further boosted in the last decade, partially due to the inclusion of PM 2.5 in China's latest NAAQS (released in 2012) and the repeated occurrences of heavily polluted PM 2.5 episodes during January of 2013 in Beijing Wang et al., 2014;Zheng et al., 2015). ...
Article
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 (fBBOC 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.
... The impact of increasing ammonia (NH3) emissions on the environment has received extensive attention [1,2]. As an essential alkaline gas and aerosol precursor in the atmosphere, NH3 reacts with acidic substances (such as nitric acid and sulfuric acid vapor) to generate secondary inorganic aerosols, and then forms fine particles that are indirectly harmful to human health [3,4]. Studies have indicated that future NH3 emission reduction is a cost-effective PM 2.5 control strategy, compared to further control of SO2 and NOx [5,6]. ...
Article
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Ammonia (NH3) is an important precursor of secondary inorganic aerosols that affect air quality and human health. Livestock production is an essential source of NH3 emissions, which exceeded half of the total NH3 emissions in China. However, our understanding of the livestock point NH3 emissions is still limited, due to the lack of both monitoring and statistical data. In this study, we established a satellite-based approach to estimating livestock point NH3 emissions by combining satellite observations and digital maps of points-of-interest (POI). Taking a case study in Hebei province over China, 1267 livestock points were identified. The point livestock NH3 emissions in 2020 ranged from 16.8 to 126.6 kg N ha−1 yr−1, with an average emission of 42.0 kg N ha−1 yr−1. The livestock NH3 emissions in Hebei showed an overall increasing trend, with a growth rate of 5.8% yr−1 between 2008 and 2020. In terms of seasonal changes, high livestock NH3 emissions mainly occurred in spring and summer, while low NH3 emissions were generally in autumn and winter. Satellite-derived point livestock NH3 emissions in Hebei were 2–4 times that of bottom-up NH3 emissions (EDGAR), suggesting that current used bottom-up emissions underestimated point livestock NH3 emissions. This study proposed a framework for the satellite-based estimation of livestock NH3 emissions, which is of great significance for relevant N management and NH3 emission reduction policy formulation.
... In both the years, during summer season no significant change has been observed in the diurnal pattern of BC concentrations while BC concentrations are showing significant change in their variations during winter season. This may be due to the increased coal consumption during winter season and also lower temperatures, low wind speed and lower boundary layers (Dan et al., 2004;He et al., 2001). Moreover, during winter season, crop residue burning activities mostly in November month significantly contributed to high concentrations of air pollutants transported from nearby areas like Punjab and Haryana (Saxena and Naik, 2018;Badrinath et al., 2006). ...
... Similar to HCl, the potential source regions for high Br concentrations were also located in the inland, demonstrating marine sources might not be the dominant source for gaseous HBr in winter of Beijing (Fig. 6b). The ratio of particulate Br / Na from previous literature in Beijing was 0.04 (He et al., 2001), which was much higher than the ratios from seawater (0.018) and crustal dust (0.0006 to 0.0008) but much closer to the ratios of biomass burning aerosols (0.01 to 0.06) (Sander et al., 2003). As discussed before, the good correlation (r = 0.70) between gaseous HCl and HBr also implied their similar origins. ...
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Gaseous hydrochloric (HCl) and hydrobromic acid (HBr) are vital halogen species that play essential roles in tropospheric physicochemical processes. Yet, the majority of the current studies on these halogen species were conducted in marine or coastal areas. Detection and source identification of HCl and HBr in inland urban areas remain scarce, thus limiting the full understanding of halogen chemistry and potential atmospheric impacts in the environments with limited influence from the marine sources. Here, both gaseous HCl and HBr were concurrently measured in urban Beijing, China, during winter and early spring of 2019. We observed significant HCl and HBr concentrations ranging from a minimum value at 1 × 108 molecules cm−3 (4 ppt) and 4 × 107 molecules cm−3 (1 ppt) up to 6 × 109 molecules cm−3 (222 ppt) and 1 × 109 molecules cm−3 (37 ppt), respectively. The HCl and HBr concentrations are enhanced along with the increase of atmospheric temperature, UVB and levels of gaseous HNO3. Based on the air mass analysis and high correlations of HCl and HBr with the burning indicators (HCN and HCNO), gaseous HCl and HBr are found to be related to anthropogenic burning aerosols. The gas–particle partitioning may also play a dominant role in the elevated daytime HCl and HBr. During the daytime, the reactions of HCl and HBr with OH radicals lead to significant production of atomic Cl and Br, up to 2 × 104 molecules cm−3 s−1 and 8 × 104 molecules cm−3 s−1, respectively. The production rate of atomic Br (via HBr + OH) is 2–3 times higher than that of atomic Cl (via HCl + OH), highlighting the potential importance of bromine chemistry in the urban area. On polluted days, the production rates of atomic Cl and Br are faster than those on clean days. Furthermore, our observations of elevated HCl and HBr may suggest an important recycling pathway of halogen species in inland megacities and may provide a plausible explanation for the widespread halogen chemistry, which could affect the atmospheric oxidation in China.
... There are also various studies investigating the sources that contribute to air pollution. For example, combustion of coal was considered a major source of air pollution in Beijing, China, along with greenhouse gas emissions (GHG) from operating vehicles and combustion of biomass (He et al., 2001). Lelieveld et al. (2015) found that GHG emissions released from residential and industrial fossil fuel combustion are the largest source causing related premature mortality worldwide. ...
Article
This paper aims to investigate the air pollution issues in Hanoi – one of the most air polluted cities in the world in recent years – on residents’ and foreign visitors’ perceptions and how their trust in the local government to establish a joint funding mechanism to mitigate air pollution in Hanoi. Such information is fundamental in order to establish an effective and efficient program to improve air quality not only in Hanoi, but also in many cities around the world. We employ a random stratified approach coupled with the contingent valuation survey and an interval regression model over a sample of 475 residents and 75 foreigners. We found that public trust is relatively low in Hanoi. Almost all respondents in the city (95%) agreed air pollution is getting worse and poor air quality severely impacts their health and increases their healthcare expenses. Over 93% of respondents claimed an urgency to mitigate air pollution in the city, but the income shares for such mitigation activities are relatively small (only 0.4–0.5% ($4.6-$6) of their household monthly incomes). Many also refuse to make any contributions because their trust in the public sector to use such monetary contributions is low. We suggest that the local government may need to improve transparency and outline a clear plan with all cash inflow and outflow information provided on a website, enabling public verification, if they expect high contributions from the private sector to share the burden.
... Various studies point out the correlation between the concentration of fine particles and epidemics, where their effect on health is the subject of interest of researchers (He et al. 2001;Marcazzan et al. 2001;Ito et al. 2006;Borrego et al. 2016;Jumaah et al. 2018;Crippa et al. 2019;David et al. 2019). Particulate matter (PM) consists of a mixture of solids and liquids in the atmosphere that is induced to the air by natural and anthropogenic sources (Querol et al. 2004;Hu et al. 2013). ...
Article
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Particulate matter (PM2.5) concentrations are a serious human health concern and global models are the common methods for PM2.5 particle estimation disregarding the local changes and factors. In this study, a polynomial model for PM2.5 particles prediction was proposed to examine the correlations among PM2.5, PM10, and meteorological parameters. The study was carried out in the north of Iraq including two provinces; Kirkuk and Sulaymaniyah. The data gathered from different sources. Two datasets have been used, collected during July 2019 and February 2020. To test our methodology, the model was applied on a small subset of the study area (5.6 km2) inside the Kirkuk province. Datasets (observation and ground truth) were utilized to examine the model. Based on the July 2019 dataset, the mean local R2 values were estimated at 0.98 and 0.97 in the north part of Iraq, and inside the Kirkuk province (the small subset), respectively. While based on the February 2020 dataset, the mean local R2 values were estimated at 0.98 inside the Kirkuk province. High values of prediction accuracies were obtained by 82% and 96% in July and February, respectively. Moreover, our findings highlighted that the health impacts and air quality varied from moderate to unhealthy in the region
... As the capital of China, Beijing (BJ) has experienced frequent air pollution in recent years (Van Pinxteren et al., 2009). In BJ and its surrounding areas, straw is often burned in early summer; hence, BC pollution has become an environmental problem that cannot be ignored (Bergin et al., 2001;He et al., 2001). However, most of the previous 45 measurements of BC were performed at ground level, and the quantitative source tracking of BC was not thorough enough. ...
Preprint
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Observations suggest that the vertical distributions of air pollutants, such as black carbon (BC), present as various types depending on the emission sources and meteorological diffusion conditions. However, the formation process and source appointment of some special BC profiles are not fully understood. In this paper, by using the Weather Research and Forecasting model coupled with chemistry (WRF-Chem) with a BC-tagging technique, we investigate the formation mechanism and regional sources of a BC peak in the free troposphere observed by aircraft flight in Beijing (BJ) on May 5th, 2018. The results show that the contribution rate of the Beijing-Tianjin-Hebei (BTH) region to the surface BC of BJ exceeded 80 % in this case. Local sources dominated BC in BJ from the surface to approximately 700 m (78.5 %), while the BC peak in the free troposphere (~4000 m) was almost entirely imported from external sources (99.8 %). Combining BC tracking and process analysis, we find that horizontal advection (HADV) and vertical advection (VADV) processes played an important role in the convergent and upward movement and the transport of BC. The BC originating from the surface in central provinces, including Shanxi (SX), Henan (HN) and Hebei (HB), was uplifted through a cyclone system 16 hours previously, transported to a height of approximately 3000 m above BJ, and then lifted by the VADV process to approximately 4000 m. At the surface, BJ and its surroundings were under the control of a weak pressure gradient, leading to the accumulation of BC within the boundary layer. Our results indicate that cyclone systems can quickly lift air pollutants, such as BC, up to the free troposphere, as well as extend their lifetimes and further affect the regional atmospheric environment and climate.
... Due to the complexity of PM 2.5 itself, the adverse health effects of PM 2.5 may vary depending on its chemical characteristics, sources, and regions. While PM 2.5 is composed of various chemical constituents, organic components comprise about 20-40% of PM 2.5 mass in urban areas (He et al. 2001;Dan et al. 2004;Putaud et al. 2010). The concentrations of organic carbon (OC) and elemental carbon (EC) are highly correlated with adverse health effects, such as cardiopulmonary diseases, which require emergency hospitalization (Lanki et al. 2006;Vedal et al. 2013;Qiao et al. 2014). ...
Article
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Lung epithelial cells serve as the first line of defense against various inhaled pollutant particles. To investigate the adverse health effects of organic components of fine particulate matter (PM 2.5 ) collected in Seoul, South Korea, we selected 12 PM 2.5 samples from May 2016 to January 2017 and evaluated the effects of organic compounds of PM 2.5 on inflammation, cellular aging, and macroautophagy in human lung epithelial cells isolated directly from healthy donors. Organic extracts of PM 2.5 specifically induced neutrophilic chemokine and interleukin-8 expression via extracellular signal-regulated kinase activation. Moreover, PM 2.5 significantly increased the expression of aging markers (p16, p21, and p27) and activated macroautophagy. Average mass concentrations of organic and elemental carbon had no significant correlations with PM 2.5 effects. However, polycyclic aromatic hydrocarbons and n-alkanes were the most relevant components of PM 2.5 that correlated with neutrophilic inflammation. Vegetative detritus and residential bituminous coal combustion sources strongly correlated with neutrophilic inflammation, aging, and macroautophagy activation. These data suggest that the chemical composition of PM 2.5 is important for determining the adverse health effects of PM 2.5 . Our study provides encouraging evidence to regulate the harmful components of PM 2.5 in Seoul.
... As shown in Fig. 6, the strongly positive correlation between K + and EC (R = 0.8) and the moderately positive correlation between K + and OC/Cl − (R = 0.55) suggested the partial contribution of biomass burning source to the measured PM 2.5 . This was also supported by the strongly positive correlation between OC and EC (R = 0.88), indicating that the main sources of OC and EC were more or less similar during the sampling period (Cao et al. 2003(Cao et al. , 2009He et al. 2001). The contribution of either regional or local biomass burning source would be further identified in the later section with the analysis of air mass backward trajectories and MODIS fire data. ...
Article
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This study investigated the concentration level of PM2.5 and its chemical compositions measured in an urban area in Hanoi city, Vietnam, during July 2020. The average value of daily PM2.5 concentrations measured for the whole sampling period was slightly lower than the national standard for ambient air quality. However, there were the polluted days when PM2.5 daily concentrations exceeded the national standard in which the average concentration level was 1.82 times higher than that for the non-polluted days when PM2.5 daily concentration was below the national standard. The organic matter (OM) (including OC) and anthropogenic secondary species (NO3−, SO42−, and NH4+) were found to be the major contributors to PM2.5 measured in the study area. Analysis of relationships among PM2.5 chemical compositions showed the strong correlations among NH4+, SO42−, and NO3−, implying a common trend in occurrence of these species in the atmosphere. The low NO3−/SO42− ratio suggested that stationary emissions are an important source of airborne pollutants in urban atmosphere in Hanoi. The high OC/EC ratios were influenced by either biomass burning or formation of secondary organic aerosol contributed to the high OC measured during the summer period. The characterization of aerosol associated with different air mass types showed that PM2.5 concentrations measured during July 2020 were mainly associated with three types of air mass: purely continental air masses (type I, relatively high PM2.5 period), a mix of maritime and dominant continental air masses (type II, PM2.5 pollution period), and a mix of continental and dominant maritime air masses (type III, low PM2.5 period). Different types of air masses with different origins and pathways coupled with the impacts of regional/local emission sources and atmospheric processes in different periods were considered as the key factors determining the chemical signatures of PM2.5, measured at the sampling site in Hanoi city during July 2020.
... Factor 1 was identified as the coal combustion source. Generally, a high concentration of Cl − was considered as the marker of coal combustion (He et al., 2001), but Cl − had the similar trend with K so that need to be set bad in PMF modeling. Interestingly, K was also found high concentration in this factor. ...
Article
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To better understand the characteristics and seasonality of trace elements in fine aerosols (PM2.5) in the Tianjin region, North China, we conducted a long-term PM2.5 sampling during July 2018 to July 2019 (n = 121) at an urban location in Tianjin. We measured 28 trace elements in PM2.5 using inductively coupled plasma mass spectroscopy (ICP-MS). Zn, As, Cd, V, and Ni, which are mainly emitted from anthropogenic sources, found to be abundant followed by the elements of natural origin and of dust, respectively. Concentrations of most of the elements varied substantially from season to season, indicating the seasonal differences in emission sources. However, V, Ni, and Cr did not show any significant seasonal variation during the whole campaign, which suggested that the impact of local emissions from the industry was significant throughout the year at Tianjin. The positive matrix factorization (PMF) analysis of the data resulted six factors, representing the sources: emissions of coal combustion, industries, biomass burning, soil dust, vehicle exhaust and secondary formation, with the relative contributions of 17.3%, 12.5%, 14.3%, 18.8%, 25.3% and 11.9%, respectively. Although the annual contribution to PM2.5 from vehicle exhaust was higher, the contributions from biomass burning, secondary formation, coal combustion and the vehicle exhaust were dominated in spring, summer, autumn and winter, respectively. This study provides insights on PM2.5 seasonal characteristics and to develop a controlling strategy for air pollution in mid-latitude coastal cities, especially in northeastern Asia.
... The average SO 4 2− concentration was the lowest in spring (4.16 μg/m 3 ), with little change in summer (20.06 μg/ m 3 ), autumn (18.44 μg/m 3 ), and winter (21.12 μg/m 3 ), although it was slightly higher in winter. He K et al. [27] studied the chemical composition of atmospheric particulate matter in Beijing from 1999 to 2000 and showed that the SO 4 2− concentration was the highest in winter (26 µg/ m 3 ) and the lowest in spring (10 µg/m 3 ). These values were higher than the those observed in this study. ...
Article
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Microorganisms are an important part of atmospheric particulate matter and are closely related to human health. In this paper, the variations in the characteristics of the chemical components and bacterial communities in PM10 and PM2.5 grouped according to season, pollution degree, particle size, and winter heating stage were studied. The influence of environmental factors on community structure was also analyzed. The results showed that seasonal variations were significant. NO3− contributed the most to the formation of particulate matter in spring and winter, while SO42− contributed the most in summer and autumn. The community structures in summer and autumn were similar, while the community structure in spring was significantly different. The dominant phyla were similar among seasons, but their proportions were different. The dominant genera were no-rank_c_Cyanobacteria, Acidovorax, Escherichia-Shigella and Sphingomonas in spring; Massilia, Bacillus, Acinetobacter, Rhodococcus, and Brevibacillus in summer and autumn; and Rhodococcus in winter. The atmospheric microorganisms in Beijing mainly came from soil, water, and plants. The few pathogens detected were mainly affected by the microbial source on the sampling day, regardless of pollution level. RDA (redundancy analysis) showed that the bacterial community was positively correlated with the concentration of particulate matter and that the wind speed in spring was positively correlated with NO3− levels, NH4+ levels, temperature, and relative humidity in summer and autumn, but there was no clear consistency among winter samples. This study comprehensively analyzed the variations in the characteristics of the airborne bacterial community in Beijing over one year and provided a reference for understanding the source, mechanism, and assessment of the health effects of different air qualities.
... The measured workroom air concentrations of Cd, Co, Cu, Fe, Mn, Pb and Zn were a factor of about 5-10 times higher than levels measured in studies of ambient air in North Carolina (US), Turin (Italy), Daejeon (Korea) and Krakow (Poland) [35][36][37][38]. Compared to PM 2.5 at two sites (campus area and downtown) in Beijing (China), air concentrations of Fe and Cu were higher by a factor of 2 and 6 in the electronic repair shops, but Mn and Ni were similar [39]. However, the Air-Pb concentrations were around 50% of the air concentrations measured at those. ...
Article
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Electronic repair workers may be exposed to lead, mercury, cadmium and other elements including rare earth elements used in electronic equipment. In this study, repair work took place in small repair shops where, e.g., televisions, radios, video players, compact discs and computers were repaired. Personal full-shift air samples of particulate matter were collected among 64 electronic repair workers in Kumasi (Ghana) and analysed for 29 elements by inductively coupled plasma mass spectrometry. Results showed that air concentrations of all elements were low. The highest air concentration was measured for iron with a geometric mean concentration and geometric standard deviation of 6.3 ± 0.001 µg/m3. The corresponding concentration of Pb and Hg were 157 ± 3 ng/m3 and 0.2 ± 2.7 ng/m3, respectively. The cerium concentration of 5 ± 2 ng/m3 was the highest among the rare earth elements. Source apportionment with ranked principal component analysis indicated that 63% of the variance could be explained by the repair and soldering of electronic components such as batteries, magnets, displays and printed circuit boards. An association between concentrations of lead in the workroom air and lead in whole blood was found (Pearson’s correlation coefficient r = 0.42, p < 0.001). There was, however, no statistically significant difference between whole blood lead concentrations in the workers and references indicating that lead did not exclusively originate from occupational exposure.
... Spatially, the central-eastern parts of China (including the NCP, YRD, and PRD), SB, and the northwestern region experienced higher PM 2.5 (80-120 μg/m 3 ) and PM 10 (120-150 μg/m 3 ) in winter, which may be due to increased anthropogenic emission activities and stable atmospheric conditions (shallower boundary layer and stagnant conditions) Li et al., 2017). In addition, several studies reported that coal combustion adds about 20%-30% of the PM 2.5 pollution in Chinese cities during winter because of the use of coal as the primary energy source for winter heating (Cao et al., 2012;He et al., 2001;Ye, 2003;Zhang et al., 2013). ...
Article
Rapid industrialization and urbanization significantly contribute to air pollution in China. Essential constituents of air pollution are fine and coarse particulate matter which are the total mass of aerosol particles with aerodynamic diameters smaller than ≤2.5 μm (PM2.5) and ≤10 μm (PM10), respectively. These particles may cause severe health effects, and impact the atmospheric environment and climate. However, the limited number of ground-based measurements at sparsely distributed air quality monitoring stations hamper long-term air pollution impact studies over large areas. Although spatial data on PM2.5 and PM10 are available from reanalysis models, the accuracy of such data may be reduced in comparison with ground data and may vary regionally and seasonally. Therefore, a long-term evaluation of reanalysis-based PM2.5 and PM10 against ground-based measurements is needed for China. In this study, surface-level PM2.5 and PM10 concentrations from 2014 to 2020 obtained from the Copernicus Atmospheric Monitoring Service (CAMS), and from the second version of Modern-Era Retrospective analysis for Research and Applications (MERRA-2) were evaluated using ground-based measurements obtained from 1675 air quality monitoring stations distributed across China. High PM2.5 and PM10 (μg/m3) concentrations from ground-based measurements were observed in many parts of China (including the North China Plain: NCP, Yangtse River Delta:YRD, Pearl River Delta: PRD, Central China, Sichuan Basin: SB, and northwestern region: Tarim Basin). The patterns of the spatial distributions of PM2.5 and PM10 obtained from CAMS and MERRA-2 across China are similar to those of the ground-based monitoring data, but the concentrations from both models are substantially different. CAMS significantly overestimates PM2.5 and PM10 over most regions, in particular over urban and desert areas, whereas MERRA-2 seasonal and annual mean concentrations were more accurate over the highly polluted areas in central and eastern China. The lowest PM2.5 and PM10 concentrations were observed over the Tibetan Plateau and Qinghai, where CAMS and MERRA-2 datasets were substantially underestimated. Furthermore, both CAMS and MERRA-2 under-and over-estimate the PM concentrations in both low and high pollution conditions. Overall, this study contributes to understanding of the reliability of reanalysis data and provides a baseline document for improving the CAMS and MERRA-2 datasets for studying local and regional air quality in China.
... These particles mainly originate from ground dust in arid and semi-arid desert areas, and their annual emissions are approximately 1500-4400 Tg [19,28]. Studies on the composition and characteristics of inhalable particulate matter in Beijing, Shanghai, Zhengzhou, Wuhan, and other large cities in China have shown that mineral particles are an important component of urban atmospheric particles, and AMPM accounts for approximately 50% of the mass concentration of APM in dry areas [29]. For example, AMPM in Beijing accounts for approximately 30-70% of the total particulate matter, and while AMPM in Chengdu is lower than in Beijing and some cities in the northwest, where it is still between 34-40% [30]. ...
Article
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Haze is the phenomenon of visibility degradation caused by extinction effects related to the physicochemical properties of atmospheric particulate matter (APM). Atmosphere heterogeneous reactions can alter the physicochemical properties of APM. Therefore, it is important to understand the atmospheric heterogeneous reactions of APM in order to reveal the cause of haze. Herein, the current situation, developmental trend, source, and composition of APM pollution in China are reviewed. Additionally, we introduce the reaction characteristics and key chemical processes of common inorganic, organic, and mixed pollutant gases on the surface of mineral particles. The effects of mineral particulate matter on aggregation, regulation, and catalysis in the formation of atmospheric aerosols and the synergistic reaction mechanism of SO2, NO2, O3, and VOCs on the surfaces of different mineral particles are summarized. The problems existing in the current research on heterogeneous reactions on the surfaces of mineral particles are also evaluated. This paper aims to gain a deep understanding of the mechanism of mineral particulate matter promoting the formation of secondary aerosols and attempts to provide theoretical support for effective haze control.
... As the capital of China, Beijing (BJ) has experienced frequent air pollution in recent years (Van Pinxteren et al., 2009). In BJ and its surrounding areas, straw is often burned in early summer; hence, BC pollution has become an environmental problem that cannot be ignored (Bergin et al., 2001;He et al., 2001). However, most of the previous measurements of BC were performed at ground level, and the quantitative source tracking of BC was not thorough enough. ...
Article
Full-text available
Observations suggest that the vertical distributions of air pollutants, such as black carbon (BC), present as various types depending on the emission sources and meteorological diffusion conditions. However, the formation process and source appointment of some special BC profiles are not fully understood. In this paper, by using the Weather Research and Forecasting model coupled with Chemistry (WRF-Chem) with a BC-tagging technique, we investigate the formation mechanism and regional sources of a BC peak in the free troposphere observed by an aircraft flight in Beijing (BJ) on 5 May 2018. The results show that the contribution rate of the Beijing–Tianjin–Hebei (BTH) region to the surface BC of BJ exceeded 80 % in this case. Local sources dominated BC in BJ from the surface to approximately 700 m (78.5 %), while the BC peak in the free troposphere (∼4000 m) was almost entirely imported from external sources (99.8 %). Combining BC tracking and process analysis, we find that horizontal advection (HADV) and vertical advection (VADV) processes played an important role in the convergent and upward movement and the transport of BC. The BC originating from the surface in central provinces, including Shanxi (SX), Henan (HN), and Hebei (HB), had been uplifted through a cyclone system 16 h previously, was transported to a height of approximately 3000 m above BJ, and was then lifted by the VADV process to approximately 4000 m. At the surface, BJ and its surroundings were under the control of a weak pressure gradient, leading to the accumulation of BC within the boundary layer. Our results indicate that cyclone systems can quickly lift air pollutants, such as BC, up to the free troposphere, as well as extend their lifetimes and further affect the regional atmospheric environment and climate.
Article
The vertical distribution of fine particles with a diameter <2.5 μm (PM $_{2.5}$ ) plays an important role in understanding the transport of air pollution and in making decisions regarding the prevention and control of regional air pollution. However, the studies of the vertical distribution of PM $_{2.5}$ were limited by the lack of monitoring data obtained with vertical sampling strategies. The lidar system can obtain the aerosol profile, which provides the possibility to measure PM $_{2.5}$ profile. Here, the vertical distributions of PM $_{2.5}$ concentrations were investigated on the basis of lidar data from January 2014 to October 2015. Linear regression, improved linear regression, and random forest (RF) models were used to retrieve the PM $_{2.5}$ concentration profile from lidar data. The models were built based on the relationship among extinction coefficient (EC), temperature (T), relative humidity (RH), and surface PM $_{2.5}$ mass concentration. Comparison of the estimated and observed PM $_{2.5}$ showed that the RF model exhibited the best inversion effect. The correlation coefficient reached 0.75, and the root mean absolute error (RMAE) and root mean square error (RMSE) were 3.94 and 21.1 μg/m³, respectively. Error analysis indicated that the estimated PM $_{2.5}$ retrieved using the linear and improved linear models (ILMs) was smaller than the observed PM $_{2.5}$ when EC was less than 0.7 km⁻¹, whereas PM $_{2.5}$ was evidently overestimated during winter pollution days. The reason might be that the effects of T and RH were inaccurately considered. Finally, the seasonal variation of the PM $_{2.5}$ profiles was investigated. Results indicated that the mass concentration of PM $_{2.5}$ was relatively large within 0.5-1.5 km, with a maximum of 60 μg/m³. The findings obtained here provide guidance for PM $_{2.5}$ vertical observation and regional pollutant transport.
Article
Luoyang is a typical heavy industrial city in China, with a coal-dominated energy structure and serious air pollution. Following the implementation of the clean air actions, the physicochemical characteristics and sources of PM2.5 have changed. A comprehensive study of PM2.5 was conducted from October 16, 2019 to January 23, 2020 to evaluate the effectiveness of previous control measures and further to provide theory basis for more effective policies in the future. Results showed that the aerosol pollution in Luoyang in autumn and winter is still serious with the average concentration of 91.1 μg/m³, although a large reduction (46.9%) since 2014. With the contribution of nitrate increased from 12.5% to 25.1% and sulfate decreased from 16.7% to 11.2%, aerosol pollution has changed from sulfate-dominate to nitrate-dominate. High NO3⁻/SO4²⁻ ratio and the increasing of NO3⁻/SO4²⁻ ratio with the aggravation of pollution indicating vehicle exhaust playing an increasingly important role in PM2.5 pollution in Luoyang, especially in the haze processes. Secondary inorganic ions contributed significantly to the enhancement of PM2.5 during the pollution period. The high value of Cl⁻/Na⁺ and EC concentration indicate coal combustion in Luoyang is still serious. The top three contributor sources were secondary inorganic aerosols (33.3%), coal combustion (13.6%), and industrial emissions (13.4%). Close-range transport from the western and northeastern directions were more important factors in air pollution in Luoyang during the sampling period. It is necessary to strengthen the control of coal combustion and reduce vehicle emissions in future policies.
Chapter
Increasing anthropogenic emissions from industrial activities, biomass burning, and vehicles over South Asia have significantly affected the atmospheric loading and chemical composition of aerosols. These emissions do not only produce particulate carbonaceous species but are also the source of several gaseous species (e.g., CO, NOx, SO2, CH4, etc.) and volatile organic compounds in the atmosphere. In this book chapter, I present the abundance pattern of particulate matter (PM), carbonaceous species (EC and OC), and diagnostic ratios (OC/EC, K⁺/OC and ¹⁴C measurements, etc.) in ambient aerosols from Asian cities. However, more emphasis is given to the chemical characteristics of aerosols and carbonaceous species during various field observations and campaigns conducted over high-altitude sites (Manora Peak, located in the Himalaya and Mt Abu located in Rajasthan in Western India) and urban locations in the Indo-Gangetic plain (Kanpur, Hisar, and Allahabad) in India.
Article
The provision of climate services for assessing and governing environmental problems such as poor air quality requires interactions between scientists and decision-makers. Air quality information services in China mainly focus on the coming days to weeks. However, users may benefit from air quality information on climate time-scales—from months to decades; hereafter air quality climate services. We focused on key decision-makers and stakeholders that are users of air quality climate services and conducted five workshops with these identified users to ascertain their priorities for air quality climate services, and the reasoning behind these priorities. We also conducted a choice-based conjoint experiment via an online survey distributed amongst regional and local Climate Centres and Environmental Monitoring Centres to assess quantitatively the decision-makers’ needs. The results from the workshops and the survey showed that the air quality climate services needs by users in China mainly relate to seasonal forecasting of winter haze events (PM2.5 levels and/or the meteorological conditions conducive to the dispersion of the air pollution); there is also some interest in long-term projections of haze under climate change and a growing interest in ozone pollution in summer. Spatial relevance is perceived to be important to regional and city-level stakeholders who prefer information on the city-level, whilst national-wide information is important for national government agencies. A high level of reliability of forecasts was needed for uptake. The findings on the needs for air quality climate services by potential users can support researchers and policy-makers in developing the scientific capacity and providing tailored, effective air quality climate services in China.
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Air pollution prediction is a burning issue, as pollutants can harm human health. Traditional machine learning models usually aim to improve the overall prediction accuracy but neglect the accuracy for peak values. Moreover, these models are not interpretable. They fail to explain the interactions between various determining factors and their impacts on air pollution. In this paper, we propose a new Hybrid Interpretable Predictive Machine Learning model for the Particulate Matter 2.5 prediction, which carries two novelties. First, a hybrid model structure is constructed with deep neural network and Nonlinear Auto Regressive Moving Average with Exogenous Input model. Second, automatic feature generation and feature selection procedures are integrated into this hybrid model. The experimental results demonstrate the superiority of our model over other models in prediction accuracy for peak values and model interpretability. The proposed model reveals how PM2.5 prediction is estimated by historical PM2.5, weather, and season. The accuracies (measured by correlation coefficients) of 1, 3 and 6-hour-ahead prediction are 0.9870, 0.9332 and 0.8587, respectively. More importantly, the proposed approach presents a new interpretable machine learning framework for time series data, enabling to explain complex dependence of multimode inputs, and to build reliable predictive models.
Conference Paper
An optimized algorithm of differential optical absorption spectroscopy based on genetic algorithm is developed to accurately detect ammonia, the maximum error is 4.29%. The results are corrected effectively with the temperature correction coefficients at 298-318K.
Article
This paper aimed to analyze the composition and pollution sources of particulate matter (PM) in the Beijing-Tianjin-Hebei region and its surrounding areas (henceforth the BTH region) during the heating season to support the mitigation and control of regional air pollution. Manual monitoring data from the China National Environmental Monitoring Network for Atmospheric PM in the BTH region were collected and analyzed during the 2016 and 2018 heating seasons. The positive definite matrix factor analysis (PMF) model was used to analyze the PM sources in BTH cities during the heating season. The main PM components were organic matter (OM), nitrate (NO3⁻), sulfate (SO4²⁻) and ammonium salt (NH4⁺). Direct emission sources have decreased since 2016, indicating the effectiveness of governmental controls on these sources; however, secondary pollution showed an increasing trend, suggesting control measures should be strengthened. Daily regional average concentrations of OM, SO4²⁻, NH4⁺, elemental carbon (EC), chloride (Cl⁻) and trace elements all showed similar trends. When air quality worsened, the concentrations of the main PM components increased, but trends of change varied among components. In 2018, concentrations of OM and chloride were highest in the Taihang Mountains, and NO3 concentrations were highest in Anyang, Hebi, Jiaozuo and Xinxiang. The SO4²⁻ concentration was highest in the southern section of the Taihang Mountains. The NH4⁺ and EC concentrations were generally highest in the central and southern regions. The concentration of crustal substances was highest in some cities in the north and central parts of the BTH region. In the 2018 heating season, the pollution level of five transmission channels showed an increasing trend in the Northwest, Southeast, Yanshan, South and Taihang Mountain channels. These findings provide a scientific basis for the continued management of atmospheric PM pollution.
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East Asian experiences frequent severe haze episodes (EPs) during winter–spring, and their causes are not fully understood. Two EPs (daily average PM2.5 > 35 μg m⁻³) occurred at Tianjin (TJ), China, and Daejeon (DJ), Korea, during late February (EP-1) and early March (EP-2) 2019. The mean total PM2.5 concentrations at the TJ and DJ sites during these events (82.9 and 66.2 μg m⁻³, respectively) were approximately three times higher than those observed during non-haze events (27.3 and 23.0 μg m⁻³, respectively). MODIS satellite RGB images suggested that aerosols were transported regionally from east Asian countries to the DJ site during EPs. After NO3⁻, the major contributors to PM2.5 during the EPs at both sites were NH4⁺, SO4²⁻, and organic carbon (OC), indicating that secondary aerosols were important in severe haze formation. During the EPs, the distributions of secondary chemical species were similar at the two sites, with coefficient of divergence (COD) values of <0.2, whereas primary chemical species had dissimilar distributions with COD values of >0.2. This suggests that secondary aerosols may be impacted by regional influences, whereas primary aerosols are subject to more local influence. The average COD values in the first two days (27–28 February) relative to the remaining days (1–7 March) were <0.2 at the DJ site during EP-2, indicating no additional local production of secondary and primary species. Sulfur oxidation ratios (SOR) were lower at the TJ site than at the DJ site, while nitrogen oxidation ratios (NOR) were higher. Gradual increases observed in SOR and NOR at the TJ site early in the EPs imply significant secondary formation of SO4²⁻ and NO3⁻. Strong correlations between aerosol liquid-water content (ALWC) and SOR and NOR at the TJ site indicate that aqueous-phase reactions were important in the formation of SO4²⁻ and NO3⁻. Although high concentrations of SO4²⁻ and NO3⁻ were observed at the DJ site, correlations between ALWC and SOR/NOR were weak with low regression gradients, implying that SO4²⁻ and NO3⁻ may have been associated with regional transport. Low COD values, and SOR and NOR values similar to those at the beginning of EP-2, imply that additional formation of SO4²⁻ or NO3⁻ at the DJ site is not active, with stagnant atmospheric conditions prevailing.
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The incineration of sacrificial offerings is a significant widely practiced custom that is also a kind of neglected air pollution source in China. Our results showed that the emission factors of particulate matter, SO2, CO, NOx, and VOCs emitted from the incineration of sacrificial offerings with purification systems were reduced by 95%, 19%, 9%, 82%, and 42%, respectively, compared with those without a purification system, revealing a significant effect of the flue gas purification system on reducing particulate matter and gaseous pollutants. The emission level of air pollutants from the incineration of sacrificial offerings remained stable before 2013 and then showed a remarkable decrease after the implementation of China´s Air Pollution Prevention Action Plan in 2013. The emissions of TSP (total suspended particulate), PM10, PM2.5, and NOx in 2009 were 8222, 6106, 5656 and 15,878 ton, respectively, obviously higher than 3434, 2551, 2305 and 8579 ton in 2019. Such trend was affected by both the quantity of incineration and the installation rate of purification systems after the Emission Standard of Air Pollutants for Crematory (GB 13801-2015) issued in China. Distinct spatial distribution of atmospheric pollutants from incineration of sacrificial offerings was found with higher in the east and south of China than the west and north of China, which is proportional to the regional economy and population. The maximum ground-level concentration typically occurred at 0.12-0.2 km from the pollution source, posing potential health risks to people entering and exiting funeral and burial sites and nearby residents.
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China has put great efforts into air pollution control over the past years and recently committed to its most ambitious climate target. Cost and benefit analysis has been widely used to evaluate the control policies in terms of past performance, future reduction potential, and direct and indirect impacts. To understand the cost and benefit analysis for air pollution control in China, we conducted a bibliometric review of more than 100 studies published over the past two decades, including the current research progress, most commonly adopted methods, and core findings. The control target in cost and benefit analysis has shifted in three stages, from individual and primary pollution control, moving to joint prevention of multiple and secondary pollutants, and then towards synergistic control of air pollution and carbon. With the expansion of the research scope, the integrated assessment model has gradually demonstrated the necessity for long-term ex-anti policy simulation, especially for dealing with complex factors. To ensure long-term air quality, climate, public health, and sustainable economic development, substantial evidence from published studies has suggested that China needs to continue its efforts in the upstream adjustment of the energy system and industrial structure with multi-regional and -sector collaboration. This cost and benefit review paper provides decision-makers with the fundamental information and knowledge gaps in air pollution control strategies in China, and direction for facing future challenges.
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Ammonia (NH3) can interact with other trace chemicals in the atmosphere, significantly impacting atmospheric chemistry and global climate change. China is a largely agricultural country with high consumption of nitrogen fertilizer and large livestock herds, resulting in high NH3 emissions. In this study, a comprehensive county-level inventory of Chinese NH3 emissions from 2013 to 2018 was compiled. Based on previous research, an estimate of NH3 emissions from household coal combustion was added to the inventory. The estimation of emissions from open biomass burning was improved by using a method based on fire radiative energy (FRE). The total NH3 emissions in China increased from 2013 (9.64 Tg) to 2015 (9.75 Tg), and then decreased to 9.12 Tg in 2018. Emissions from fossil fuels reached a peak value in 2018, accounting for 8.4% of total emissions, while fertilizer application and livestock waste were responsible for fewer emissions than in previous years, accounting for 27.7% and 49.9% of the total from non-fossil fuel sources, respectively. The highest emission rates were in central and southwestern China. Seasonally, NH3 emissions peaked in spring and summer. The inventory had a 1-km spatial resolution and a monthly temporal resolution, which confirmed its suitability for global and regional air quality simulations.
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Nowadays, the fine particle pollution is still severe in some megacities of China, especially in the Sichuan Basin, southwestern China. In order to understand the causes, sources, and impacts of fine particles, we collected PM2.5 samples and analyzed their chemical composition in typical months from July 2018 to May 2019 at an urban and a suburban (background) site of Chengdu, a megacity in this region. The daily average concentrations of PM2.5 ranged from 5.6-102.3 μg/m³ and 4.3-110.4 μg/m³ at each site. Secondary inorganics and organic matters were the major components in PM2.5 at both sites. The proportion of nitrate in PM2.5 has exceeded sulfate and become the primary inorganic component. SO2 was easier to transform into sulfate in urban areas because of Mn-catalytic heterogeneous reactions. In contrast, NO2 was easily converted in suburbs with high aerosol water content. Furthermore, organic carbon in urban was much greater than that in rural, other than elemental carbon. Element Cr and As were the key cancer risk drivers. The main sources of PM2.5 in urban and suburban areas were all secondary aerosols (42.9% 32.1%), combustion (16.0%, 25.2%) and vehicle emission (15.2%, 19.2%). From clean period to pollution period, the contributions from combustion and secondary aerosols increased markedly. In addition to tightening vehicle controls, urban areas need to restrict emissions from steel smelters, and suburbs need to minimize coal and biomass combustion in autumn and winter.
Chapter
The effects of atmospheric fine particles on human health have become an utmost concern worldwide. Particulate matter is a complex and dynamic combination of a mixture of solid and liquid substances with several biological and chemical components. Various toxicological and epidemiological studies indicated that the fine particles create several health issues such as respiratory and cardiopulmonary disorders. The present chapter provides the information regarding regulations and standards set by various countries and organizations to regulate the atmospheric concentration of fine particles and discuss the primary and secondary sources of fine particulate pollution. This chapter demonstrated the biological and chemical components of fine particles that play a critical role in the toxicological implications of fine particulates. In addition, the justifications for the origin or sources of biological and chemical compositions and their impacts on human health become a concern in this chapter. The current chapter also aims to provide a brief overview of the molecular mechanisms connecting fine particulate exposure and health effects.KeywordsFine particlesSourcesCompositionBio-aerosolToxicityHealth effectsMechanism of action
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Organic aerosol (OA) generally accounts for a large fraction of fine particulate matter (PM2.5) in the urban atmosphere. Despite significant advances in the understanding their emission sources, transformation processes and optical properties in the submicron aerosol fraction (PM1), larger size fractions - e.g., PM2.5 - still deserve complementary investigations. In this study, we conducted a comprehensive analysis on sources, formation process and optical properties of OA in PM1 and PM2.5 under haze and foggy environments in the Yangtze River Delta (eastern China), using two aerosol chemical speciation monitors, as well as a photoacoustic extinctiometer at 870 nm. Positive matrix factorization analysis - using multilinear engine (ME2) algorithm - was conducted on PM1 and PM2.5 organic mass spectra. Four OA factors were identified, including three primary OA (POA) factors, i.e., hydrocarbon-like OA (HOA), cooking OA (COA), and biomass burning OA (BBOA), and a secondary OA (SOA) factor, i.e., oxidized oxygenated OA (OOA). An enhanced PM1-2.5 COA concentration was clearly observed during cooking peak hours, suggesting important contribution of fresh cooking emissions on large-sized particles (i.e., PM1-2.5). The oxidation state and concentration of PM2.5 HOA were higher than that in PM1, suggesting that large-sized HOA particles might be linked to oxidized POA. High contribution (44%) of large-sized OOA to non-refractory PM2.5 mass was observed during haze episodes. During foggy episodes, PM1 and PM2.5 OOA concentrations increased as a positive relationship over time, along with an exponential increase in the PM2.5-OOA to PM1-OOA ratio. Meanwhile, OOA loadings increased with the aerosol liquid water content (ALWC) during foggy episodes. Random forest cross-validation analysis also supported the important influence of ALWC on OOA variations, supporting substantial impact of aqueous process on SOA formation during haze and/or foggy episodes. Obtained results also indicated high OOA contributions (21%–36%) and low POA contributions (6%–14%) to the PM2.5 scattering coefficient during haze and foggy episodes, respectively. Finally, we could illustrate that atmospheric vertical diffusion and horizontal transport have important but different effects on the concentrations of different primary and secondary OA factors in different particle size fractions.
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Regional transport of air pollutants is modulated by large‐scale synoptic circulation, which has been poorly understood for heavy air pollution in the downstream receptor region. In the present study of 5‐year (2015–2019) observation, we targeted the Twain‐Hu Basin (THB), a region of heavy PM2.5 pollution over central China, to investigate the regulation of synoptic circulation governing regional PM2.5 transport for heavy air pollution. It was found that regional transport of PM2.5 predominated 65.2% of the heavy pollution events (HPEs) over the THB based on the statistics of observational environment and meteorology. By employing the FLEXPART‐WRF model, the regional transport of PM2.5 from upwind areas in central and eastern China (CEC) to receptor region in the THB was identified with three prominent pathways in the northerly, northeasterly, and easterly directions respectively. We then used T‐mode principal component analysis in conjunction with the K‐means cluster method to categorize synoptic circulations, and it was recognized that three regional PM2.5 transport pathways for the HPEs over central China were governed respectively by three patterns of synoptic circulation over CEC with (a) weak high air pressure to the north (13.3%), (b) strong high air pressure to the northeast (46.7%), and (c) weak high air pressure to the east (40.0%). This study reveals a significant modulation of large‐scale synoptic circulation for regional transport of air pollutants in environmental change.
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Carbonaceous fractions throughout the normal period and lockdown period (LP) before and during COVID-19 outbreak were analyzed in a polluted city, Zhengzhou, China. During LP, fine particulate matters, elemental carbon (EC), and secondary organic aerosol (SOC) concentrations fell significantly (29%, 32% and 21%), whereas organic carbon (OC) only decreased by 4%. Furthermore, the mean OC/EC ratio increased (from 3.8 to 5.4) and the EC fractions declined dramatically, indicating a reduction in vehicle emission contribution. The fact that OC1–3, EC, and EC1 had good correlations suggested that OC1–3 emanated from primary emissions. OC4 was partly from secondary generation, and increased correlations of OC4 with OC1–3 during LP indicated a decrease in the share of SOC. SOC was more impacted by NO2 throughout the research phase, thereby the concentrations were lower during LP when NO2 levels were lower. SOC and relative humidity (RH) were found to be positively associated only when RH was below 80% and 60% during the normal period (NP) and LP, respectively. SOC, Coal combustion, gasoline vehicles, biomass burning, diesel vehicles were identified as major sources by the Positive Matrix Factorization (PMF) model. Contribution of SOC apportioned by PMF was 3.4 and 3.0 μg/m³, comparable to the calculated findings (3.8 and 3.0 μg/m³) during the two periods. During LP, contributions from gasoline vehicles dropped the most, from 47% to 37% and from 7.1 to 4.3 μg/m³, contribution of biomass burning and diesel vehicles fell by 3% (0.6 μg/m³) and 1% (0.4 μg/m³), and coal combustion concentrations remained nearly constant. The findings of this study highlight the immense importance of anthropogenic source reduction in carbonaceous component variations and SOC generation, and provide significant insight into the temporal variations and sources of carbonaceous fractions in polluted cities.
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In Beijing area, the precious stone objects often suffer from the black crusts on the specific parts of the objects, in order to understand the forming mechanism of the black crusts, samples from the stone sculptures in Beijing Stone Carving Art Museum, ZHIHUA Temple and Museum of Western Zhou Yandu Relics were taken and studied. Nondestructive measurement was carried out firstly to acquire main elements of the samples by portable X-ray spectrum (pXRF). Morphology and microstructure of typical black crust samples were examined by ultra-depth of field microscope (UDFM) and scanning electron microscopy coupled with energy dispersive spectroscopy (SEM-EDS). Compositions of black crusts and body rocks were evaluated with X-ray diffraction (XRD), Raman spectra and mapping. Inductively coupled plasma optical emission spectrometry (ICP-OES) and pyrolysis-gas chromatography/mass spectrometry (Py-GCMS) were used to identify the major pollution sources leading to the black crusts. Through this study, the composition of the black crusts was revealed. Different gypsum crystals and carbonaceous species were found. Pollutant elements analysis and pyrolysis products provide indicators of the pollution sources. As consequence of strong photochemical oxidation processes and the high temperature from June to September in Beijing, more acid rain precursors can be formed. Frequent sulphation process occurs on the CaCO3/CaMg(CO3)2 surface. Combining morphology results and atmospheric data, the formation of black crusts in Beijing can be deduced.
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Organic carbon (OC) and elemental carbon (EC) are operationally defined by the analysis methods, and different methods give in different results. The IMPROVE Iinteragency Monitoring of protected Visual Environments) and NIOSH (National Institute of Occupational Safety and Wealth) thermal evolution protocols present different operational definitions. These protocols are applied to 60 ambient and sonrce samples from different environments using the same instrument to quantify differences in implemented protocols on the same instrument. The protocols are equivalent for total carbon sampled on quartz-fiber filters. NIOSH EC was typically less than half of IMPROVE EC. The primary difference is the allocation of carbon evolving at the NIOSH 850 degrees C temperature in a helium atmosphere to the OC rather than EC fraction. increasing light transmission and reflectance during this temperature step indicate that this fraction should he classified as EC. When this portion of NIOSH OC is added to NIOSH EC, the IMPROVE and NIOSH analyses are in good agreement. The most probable explanation is that mineral oxides in the complex particle mixture on the filter are supplying oxygen to neighboring carbon particles at this high temperature. This has been demonstrated by the principle of the thermal manganese oxidation method that is also commonly used to distinguish OC from EC, For both methods, the optical pyrolysis adjustment to the EC fractions was always higher for transmittance than for reflectance. This is a secondary cause of differences between the two methods, with transmittance resulting in a lower EC loading than reflectance. The difference was most pronounced for very black filters on which neither reflectance nor transmittance accurately detected further blackening due to pyrolysis.
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SJVAQS/AUSPEX acquired PM(2.5) and PM(10) samples at ten sites in Central California for five ozone episodes over 14 intensive sampling days. Four sample sets per day were acquired for 5 and 7 h durations and measured for particle mass; elements; water-soluble chloride, nitrate, sulfate, ammonium, sodium, and potassium ions; and organic and elemental carbon. Gaseous ammonia, nitric acid, and sulfur dioxide concentrations were acquired with absorbent filter material. To guard against contamination of these gases after sampling, the filter packs were sealed and refrigerated prior to analysis. Crustal species such as aluminum, silicon, calcium, titanium, iron, and calcium, were found in coarse particles at most sites. Substantial amounts of sodium and chloride were detected in the coarse particle fraction at the coastal Point Reyes site. Organic carbon and sulfate were the most abundant species in the PM(2.5) fraction. Elemental carbon concentrations were low at all sites. Only one 24 h average PM(0) concentration exceeded the U.S. PM(10) standard of 150 mu g m(-3) during the study period, and this occurred at the agricultural-oriented Buttonwillow site. The highest concentrations of most chemical species were found at sites in the Southern San Joaquin Valley.
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Airborne fine particle mass concentrations in Southern California have declined in recent years. Trends in sulfate and elemental carbon (EC) particle concentrations over the period 1982-1993 are consistent with this overall improvement in air quality and help to confirm some of the reasons for the changes that are seen. Fine particle sulfate concentrations have declined as a strict sulfur oxides (SOx) emission control program adopted in 1978 was implemented over time. Fine particle elemental (black) carbon concentrations have declined over a period when newer diesel engines and improved diesel fuels have been introduced into the vehicle fleet. Organic aerosol concentrations have not declined as rapidly as the EC particle concentrations, despite the fact that catalyst-equipped cars having lower particle emission rates were introduced into the vehicle fleet alongside the diesel engine improvements mentioned above. This situation is consistent with the growth in population and vehicle miles traveled in the air basin over time. Fine particle ammonium nitrate in the Los Angeles area atmosphere contributes more than half of the fine aerosol mass concentration on the highest concentration days of the year, emphasizing both the need for accurate aerosol nitrate measurements and the likely importance of deliberate control of aerosol nitrate as a part of any serious further fine particle control program for the Los Angeles area.
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Airborne fine particles are a mixture of various components and are emitted by different sources. Short-term and long-term epidemiological studies have associated fine particles with adverse health effects, excess mortality, respiratory and cardiovascular diseases. There are indications that the health effects are more associated with the fine fraction of PM10 and with ultrafine particles (< 0.1 m) than with the coarse fraction. Recently, diesel exhaust and vehicular emissions have been identified in epidemiological studies as important factors for explaining adverse health effects of fine particles; there are also indications for a biological mechanism. For acid aerosols and sulfate particles, a biological mechanism is proposed in the literature, but results from epidemiological studies are not entirely conclusive. Commonly, no threshold is found and a linear doseresponse relationship is proposed. The spatial and temporal distribution of fine particle levels may vary substantially. L...
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The Buddhist cave temples at Yungang, China, are soiled at a rapid rate by the deposition of airborne particles. Average mass deposition rates to horizontal surfaces of 13.42 μg m-2 s-1 outdoors and 5.23 μg m-2 s-1 inside Cave 6 were measured over a 1 yr period in 1991-1992. These rates are comparable to the rates inferred by examination of historically accumulated deposits within the caves. The surface area coverage by coarse particles is dominated by particles larger than about 10-20 μm in diameter, while the mass flux is dominated by even larger particles greater than 20-30 pm in diameter. Comparison of the deposition rate in Cave 6, which retains its wooden temple front structure, to that in Cave 9 which is open to the outdoors shows that the temple front does provide some protection. During spring 1991, the deposition rate to horizontal surfaces in Cave 6 was 4.5 μg m-2s-1 compared to 13.4 μg m-2s-1 in Cave 9 and 21.5 μg m-2s-1 outdoors.
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Components of the near-ground urban aerosol in Beijing, China, which are derived from natural and pollution sources, have been identified by means of PIXE analysis of particle size fractionated samples and relationships among the concentrations of 18 elements. Samples were collected in city center and outlying suburban and rural locations on five days in July and December 1980. The panicle size distributions of most elements were bimodal, with a gradual progression from mainly coarse mode Ca, Ti and Al to mainly fine mode S, As, and Br. Pb, Zn and Cu occurred mainly in fine particles and were apparently pollutants derived from the combustion of coal and other fuels, but not gasoline. Fine particle Cr, Mn and Fe concentrations were especially high on one July day and may have derived from a pulse of industrial air pollution. Si concentrations were singularly high in ultra-fine particles as if from the condensation of high temperature vapors from coal combustion. Coarse particles in the city center were apparently from local surface dust raised by vehicle traffic, and they were enriched in Pb, Zn and Cu compared to a rural location, suggesting a significant degree of city soil contamination by fine pollution aerosol fallout over time.
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Results of our aerosol study, performed during 1983–1984 in Beijing, demonstrate that ambient carbonaceous aerosols are derived principally from coal combustion. Different SO2 oxidation processes have been observed in summer and winter. The winter sulfate appears to be produced locally and associated with products of incomplete combustion.
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The elemental composition of duplicate aerosol samples from north China, collected in particle size fractions by eight-stage cascade impactors on the Great Wall, near Beijing, is reported for 21 elements measured by particle induced X-ray emission analysis. Meteorological conditions during sampling on 1 April 1980 indicated that relatively clean northerly air from Mongolia and Siberia was sampled. Coarse terrestrial dust and additional fine aerosol components mainly of 0.5–1 μm aerodynamic diameter could be distinguished. Relative elemental abundances in the coarse mode resembled earth crust composition. Those in the fine mode resembled the South Pole aerosol, and fine mode elemental concentrations were low enough to suggest approximately background levels of several trace metals.
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This paper presents results from a study of soot pollution problems in the Beijing-Tianjin area of China in 1983–1984. Soot is one of the main air pollutants in northern China. The average particular carbon concentration in the air is about 30 μg m and the source is mainly coal combustion. Based on these experiments, using the moving parcel method, we estimate the conversion rate for oxidation of SO2 to sulfate to be in the range 2.2%–5.7% h. Contributions of the different components of the aerosol to visibility reduction have been calculated. The apparent sulfate and soot contributions to the visibility decrease are 52%–58% and 22%–29%, respectively. Results of a laboratory study indicate that transition metal ions and soot can be important catalysts for the oxidation of S(IV) in aqueous solution. Under ultraviolet light, transition metal catalysis is faster, while absence of such light favors catalysis by soot. Thus soot can negatively affect visibility both directly, by light absorption and scattering, and indirectly, through catalysis of SO2 oxidation.
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Three size fractions of particulate matter (PM), i.e., fine particles (PM{sub 2.5}), coarse particles (PM{sub 2.5--10}), and PMââ, were measured at the school yards of eight elementary schools in four large Chinese cities during 1995 and 1996. These schools, one located in an urban district and one in a suburban district in each city, served as principal bases for an air pollution epidemiologic study. All PM samples were collected on Teflon filters using dichotomous samplers and analyzed gravimetrically for PM mass concentrations. A subset of the samples collected were analyzed for elements using a standard XRF technique. Annual means of PMââ concentrations, in which 52--75% were PM{sub 2.5}, ranged from 68 to 273 μg/m³ across the eight sampling sites. Within each city, the urban site had higher annual means of all measured PM size fractions. Reported in the paper were also the concentrations of eight elements which were likely to be associated with urban pollution sources. The concentrations of these elements were found to be substantially higher in fine particles than in coarse particles, suggesting that urban pollution may have a larger impact on fine particles. This is further supported by the results form comparing elemental enrichment factors for fine particles with those for coarse particles. It is clearly demonstrated that the elements were enriched more in fine particles than in coarse particles.
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The Yungang Grottoes are a collection of man-made cave temples dating from the 5th century A.D. that now are situated in the middle of one of China's largest coal mining regions. Air pollutant particles enter these caves and deposit onto the more than 50 000 stone carvings contained within the caves, leading to rapid soiling of the sculptures. In order to study this problem, computer-based models have been combined that simulate the air flow into the caves and particle deposition within the caves. The evolution of the airborne particle concentration and size distribution is tracked as outdoor air is drawn into the caves by a natural convection flow that is driven by the temperature difference between the outdoor air and the interior walls of the caves. Particle deposition rates are computed from the boundary layer flows along the surfaces within the caves. Predicted coarse airborne particle (diameter > 2.3 μm) size distribution and coarse particle deposition fluxes to horizontal surfaces within caves 6 and 9 at Yungang compare closely to experimental observations made during the period April 15−16, 1991. It is found that horizontal surfaces within caves 6 and 9 at Yungang would become completely covered by a full monolayer of particles in only 0.3−0.5 yr under the April conditions studied here and will be soiled even more rapidly under annual average conditions. The model developed here can be used in the future to compute the effects of particle filtration systems and/or altered ventilation rates on soiling within the grottoes.
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A chemical database for PM2.5 and PM2.0 aerosols has been assembled for various sampling sites in China. The primarily urban sites, sampled from 1980 to 1993, include Beijing, Tianjin, Wuhan, Lanzhou, and Guangzhou. From 13 to 22 inorganic chemical elements were measured but few secondary and organic compounds. Previous source resolution studies are briefly summarized. A mass balance for the Beijing aerosol indicates that the three largest components are carbon-containing matter (50%), (NH4)2SO4 (18%), and silicon compounds (12% expressed as silica). Silicon concentrations in Beijing and Lanzhou were 26−36 times higher than Los Angeles. The fine silicon probably comes from coal combustion, crustal sources, and rice straw burning, but the relative amounts are not certain. Mass concentration data for Chinese cities were compared among themselves and with downtown Los Angeles using scatter diagrams. Compositions of the Beijing aerosol were generally higher than Los Angeles; the Beijing PM2.0 mass in 1992−1993 was about 5 times that of Los Angeles PM2.5 in 1986. In addition to significant changes over the years measurements were made, seasonal and regional variations were also observed. Mass fractions of crustal elements Ca, Al, Mn, Ti, and Fe in Beijing were higher than Los Angeles, while Cu, Pb, Zn, Cr, and Ni were lower. For Lanzhou (1983) and Tianjin (1984), most PM2.5 components show higher concentrations than central Beijing.
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Energy dispersive X-ray analysis of elements and reagent thin-"lm test of particulate nitrate and sulfate were carried out to examine individual dust particles collected in Beijing during "ve dust-storm events occurring in spring of 1995 and 1996. Dominant particles were electron-opaque and had irregular shapes during the dust-storm periods, and their size was frequently in the range larger than 1 m (diameter). Besides, some mineral particles that showed regular cubic shapes were found in the range from 0.1 to 2 m. Their X-ray spectrums indicated calcium was abundant and little or no other elements with atomic number larger than 11 existed in such particles. They were supposed to be emitted initially from construction sites, and then formed through crystallization in the atmosphere. Their most possible composition was CaO or Ca(OH) . It was estimated that 93% of the collected electron-opaque particles are dust particles and the cubic particles in term of number frequency. On reagent "lms, few dust particles reacted apparently with barium chloride suggesting there was no water-soluble sulfate on the surface of dust particles although X-ray spectrums of about 14.6% of dust particles showed peaks of sulfur. The frequency of nitrate-containing particles in dust particles was 10.8%, which was much smaller than that in mineral particles collected in non-dust-storm periods. These results suggest that almost no sulfate is formed and nitrate is hardly formed on the surface of dust particles during their transport from source areas to Beijing.
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The burden of ill human health attributable to particulate air pollution is a critical problem of growing concern. In developing countries it is not uncommon to experience today the same particulate matter levels that characterized the devastating "London fog episodes" of the 1950s which resulted in over 4000 cases of premature mortality and countless cases of exacerbated morbidity related health endpoints. This literature review gives an overview of the situation in developing countries by synthesizing the pertinent information relating to source and concentration of particulate matter, to exposure-response curves, the observed health effects, the plausibility of biological mechanisms, and health related costs. The feasibility of extrapolating data derived from developed countries to estimate health effects for developing countries is briefly considered. There is little doubt that particulate matter causes or contributes to premature mortality and morbidity related health endpoints in developing countries. Only the most easily observed and quantified health effects have been identified to date. There is increasing proof that the most harmful effects of particulate matter are related to the size of the particle, as particles decrease in size, they are hypothesized to either increase in acidity or in their ability to penetrate into the lower airways. Even more than in developed countries, personal exposure to particulate matter in developing countries has been found to be badly represented by ambient monitors. Additionally, it may be much more depending on indoor sources and housing types than in developed countries. Previous studies on costs of particulate air pollution to society in developing countries are rare, and many different approaches have been used. They do not account for loss of welfare, disutility or loss of productivity, which may cause the greatest costs. Thoughts have been given to use the Disability Adjusted Life Year (DALY) to assess health costs for a certain disease and for a given population. DALYs would allow for comparable measures of health costs or or benefits to be quantified and compared across populations and regions of the world.
Article
Aerosol samples for PM10 (particulate matter with aerodynamic diameters less than 10 um) were collected from September 1993 to August 1994 at five sites representing the major land use patterns in Brisbane, a subtropical coastal city in Australia. The samples collected were analysed by techniques such as ion beam analysis and the integrating plate laser absorption method, and the chemical composition of the samples was reconstructed from the observed elemental composition. For these PM10 samples, the major components, on average, were crustal matter (25% by mass), organics (17%), sea salt (12%), elemental carbon (10%) and ammonium sulphate (7%). Aerosol samples of PM2.5 (particulate matter with aerodynamic diameter less than 2.5 μm) were collected by a dichotomous sampler at one of the sites (GU), a site on university buildings located in a suburban area of Brisbane but surrounded by a buffer zone provided by a forest conservation area. A high average fine Br/Pb ratio of 0.36 in the GU samples, which is close to that in vehicle exhausts, indicates that this site probably has low background levels of lead even though there has been significant traffic in the area for 20 years, so the forest area is an effective buffer to road dust from the surrounding suburbia. Temporal trends at this site suggest that road side dust and industry-sourced crustal matter could contribute to more than half of the mass of crustal matter. Seasonal meteorological conditions which determine the dispersion of pollutants out of Brisbane and the continuous input of rural dust into Brisbane are potentially important factors influencing the level of crustal matter in Brisbane. However, major rural dust events do not considerably increase the seasonal average level of crustal matter. Also, apart from significant local influences at some sites (such as heavy road traffic network or a cement factory), the results from the GU site show a similar level of elemental and chemical components from anthropogenic sources to sites in heavy industrial and commercial/light industrial sites, indicating that most anthropogenic emissions are evenly and widely distributed in Brisbane.
Article
The possibility of using a two step method of identifying and quantifying air pollution emissions in an urban environment was examined in this paper. The procedure uses a numerical model called Target Transformation Factor Analysis (TTFA) to estimate source emission profiles using ambient trace element air concentration data. The profiles estimated by TTFA are then employed in a Chemical Mass Balance (CMB) source apportionment analysis for an air shed. Other known sources are estimated using source signatures from the literature. The results show that TTFA can be used to provide quantitative estimates of air pollution source profiles for an urban center in China. The number of profiles for unique source types was limited for this data set since emissions from certain types of sources co-varied during each sampling day. Consequently, the CMB analyses that applied the TTFA source profiles needed to be supplemented with standard U.S. EPA source profiles. TTFA can identify source categories of airborne pollution for specific locations, as well as give quantitative data on the composition of the emissions from those source types. The source profiles obtained through a TTFA can be used in a chemical mass balance source apportionment calculation. Including source profiles estimated by TTFA in a chemical mass balance analysis provides a comprehensive source apportionment methodology which can help researchers more accurately characterize the air pollution source types that pose the greatest concern to human health.
Article
Low-volume particulate samples (equivalent to PM10 size distributions) were taken during the fall and early winter of 1998–1999 in the cities of Dongying, Jinan, and Qingdao in Shandong Province, and in the independent districts of Shanghai and Beijing. X-ray diffraction and transmission analysis and polarizing optical microscopy were performed on the samples. The samples from all cities and districts contained the major components of quartz, feldspar, clays, calcium sulfates, and carbonates (except Qingdao). The Qingdao sample was surprising in that no carbonate components were observed. Carbonaceous matter dominated in all wintertime samples, but with a large variety of the mineral components also being present. It was also observed that some of the airborne calcium carbonate (calcite), an important fugitive dust constituent, reacted with sulfuric acid aerosols from industrial sources, to form two hydrated forms of calcium sulfate. The metastable carbonate, vaterite, was also observed in association with high-carbon samples, but it's formation as an in situ reaction product is uncertain.
Article
The thermal/optical reflectance method of carbon analysis developed by Huntzicker et al. (in Particulate Carbon, Atmospheric Life Cycle, edited by Wolff G. T. and Klimisch R. L., pp. 79–88, Plenum Press, New York, 1982) has been adapted by several laboratories for the quantification of organic and elemental carbon on quartz-fiber filter deposits. While the principle used by these laboratories is identical to that of Huntzicker et al., the details differ with respect to calibration standards, analysis time, temperature ramping and volatilization/combustion temperatures. This paper reports a variation on this method which has been applied to over 27,000 samples taken in more than a dozen urban and regional air quality studies in the U.S.A. In this variation, a 0.5 cm² punch from a dozen urban and regional air quality studies in 120, 250, 450 and 550°C in a pure helium atmosphere, then to combustion at temperatures of 550, 700 and 800°C in a 2% oxygen and 98% helium atmosphere. The carbon which evolves at each temperature is converted to methane and quantified with a flame ionization detector. The seven separate carbon fractions facilitate evaluation of the method and increase the information content concerning the samples.
Article
During the summer and fall of 1987, the Southern California Air Quality Study (SCAQS) was conducted at more than 40 locations to acquire a database with meteorological, air quality, and visibility measurements, and to assess the causes of elevated ozone and suspended particulate matter concentrations throughout metropolitan Los Angeles, CA (the South Coast Air Basin—SoCAB). PM2.5 and PM10 (particles with aerodynamic diameters equal to or less than 2.5 and 10 μm, respectively) mass, elements, water-soluble chloride, nitrate, sulfate, ammonium ions, organic and elemental carbon as well as gaseous ammonia, nitric acid, and sulfur dioxide were measured on eleven episode days during the summer and six episode days during the fall. This paper examines the statistical, temporal, and spatial distributions of the SCAQS aerosol measurements. PM2.5 constituted one-half to two-thirds of PM10 at all sampling sites. PM10 mass concentrations were highest during the fall and were dominated by PM2.5. Nitrate, sulfate, ammonium, and organic and elemental carbon were the most abundant species in the PM2.5 fraction. The coarse particle (PM10 minus PM2.5) fraction was enriched with soil-related elements (e.g. aluminum, silicon, calcium, iron) at the inland sites and with marine-related elements (e.g. sodium, chloride) at the coastal sites. Average concentrations for most chemical compounds were higher during the fall than during the summer, except for sulfate which was more abundant during the summer. PM2.5 nitrate and ammonium concentrations were negatively biased for daytime samples with respect to nighttime samples, consistent with diurnal changes in temperature and the effect of these changes on the equilibrium between particulate ammonium nitrate and gaseous ammonia and nitric acid. Highest sulfur dioxide concentrations were found at the Long Beach site, the location closest to SoCAB oil refineries and ship traffic; and highest ammonia concentrations were found at the Rubidoux site, a location downwind of dairies and agricultural operations.
Article
Although China is struggling with major urban air quality problems, its most serious health problem is indoors.