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This study investigated the size-segregated carbonaceous components of particulate matter (PM), including ultrafine particles (UFP or PM0.1), across three distinct urban settings in Phnom Penh, Cambodia: an educational site (University of Health Sciences, UHS), an institutional site (Ministry of Environment, MoE), and a residential area near a landfill. A cascade impactor-type sampler equipped with an inertial filter was used to collect size-segregated particles down to UFPs. Carbonaceous species, including organic carbon (OC) and elemental carbon (EC), were analyzed using a thermal/optical carbon analyzer to determine their composition and ratios. The results indicated no significant differences in mass concentration between weekdays and weekends at all sites; however, PM profiles varied across the location. The UHS site displayed higher EC levels in UFP, with concentrations suggesting significant local vehicular emissions, underscored by a lower OC/EC ratio (2.39 ± 1.13) compared to other sites. In contrast, the landfill site exhibited higher OC components in finer particles, suggesting emissions from organic sources such as waste burning and cooking activities, evidenced by higher OC/EC ratios across all particle sizes (e.g., OC/EC ratio in UFP at 3.78 ± 0.98). The MoE site presented a balanced profile with moderate levels of both OC and EC, influenced by its proximity to natural dispersion factors like the Tonle Sap River. Additionally, air mass backward trajectory analysis integrated with hotspot data indicated transboundary influences, particularly from agricultural burning in surrounding provinces, including Vietnam. Therefore, both local and transboundary emissions influenced the PM levels in Phnom Penh city. [ABSTRACT FROM AUTHOR]

The goals of the "dual carbon" program in China are to implement a series of air pollution policies to reduce the emission of carbon-bearing particulate matter (PM). Following improvements in the reduction in carbon emissions in Handan City, China, fine particulate matter (PM2.5) was collected in the winters from 2016 to 2020 to characterize the concentrations and sources of carbonaceous components in PM2.5. Trend analysis revealed that both organic carbon (OC) and elemental carbon (EC) concentrations significantly decreased. The proportion of total carbon aerosol (TCA) in PM2.5 decreased by 47.0%, highlighting the effective reduction in carbon emissions. Secondary organic carbon (SOC) concentrations increased from 2016 (12.86 ± 14.10 μg·m−3) to 2018 (36.76 ± 21.59 μg·m−3) and then declined gradually. SOC/OC was larger than 67.0% from 2018 to 2020, implying that more effective synergistic emission reduction measures for carbonaceous aerosol and volatile organic compounds (VOCs) were needed. In the winters from 2016 to 2020, primary organic carbon (POC) concentrations reduced by 76.1% and 87.6% under a light/moderate pollution period (LP) and heavy/severe pollution periods (HPs), respectively. The TCA/PM2.5 showed a decreasing trend under LP and HP conditions, decreasing by 42.1% and 54.7%, respectively. Source analysis revealed that carbonaceous components were mainly from biomass burning, coal combustion and automotive exhaust emissions in the winters of 2016 and 2020. OC/EC and K+/EC analysis pointed out that air pollutant reduction measurements should focus on rectification biomass fuels in the next stage. Compared with 2016, the contributions of automotive exhaust emissions decreased in 2020. OC and EC concentrations decreased due to control measures on automotive exhaust emissions. [ABSTRACT FROM AUTHOR]

The goals of the “dual carbon” program in China are to implement a series of air pollution policies to reduce the emission of carbon-bearing particulate matter (PM). Following improvements in the reduction in carbon emissions in Handan City, China, fine particulate matter (PM2.5) was collected in the winters from 2016 to 2020 to characterize the concentrations and sources of carbonaceous components in PM2.5. Trend analysis revealed that both organic carbon (OC) and elemental carbon (EC) concentrations significantly decreased. The proportion of total carbon aerosol (TCA) in PM2.5 decreased by 47.0%, highlighting the effective reduction in carbon emissions. Secondary organic carbon (SOC) concentrations increased from 2016 (12.86 ± 14.10 μg·m−3) to 2018 (36.76 ± 21.59 μg·m−3) and then declined gradually. SOC/OC was larger than 67.0% from 2018 to 2020, implying that more effective synergistic emission reduction measures for carbonaceous aerosol and volatile organic compounds (VOCs) were needed. In the winters from 2016 to 2020, primary organic carbon (POC) concentrations reduced by 76.1% and 87.6% under a light/moderate pollution period (LP) and heavy/severe pollution periods (HPs), respectively. The TCA/PM2.5 showed a decreasing trend under LP and HP conditions, decreasing by 42.1% and 54.7%, respectively. Source analysis revealed that carbonaceous components were mainly from biomass burning, coal combustion and automotive exhaust emissions in the winters of 2016 and 2020. OC/EC and K+/EC analysis pointed out that air pollutant reduction measurements should focus on rectification biomass fuels in the next stage. Compared with 2016, the contributions of automotive exhaust emissions decreased in 2020. OC and EC concentrations decreased due to control measures on automotive exhaust emissions.

In the background of carbon neutrality, carbon emissions are basked in the attention. As a significant source of carbon emissions, the emission characteristics of carbon plant should be known. Particulate matter in flue gas was collected in a carbon plant in Tongliao. The chemical components in PM10 and PM2.5 were analyzed, and source profile of carbon plant was established. The results showed that the mass fractions of EC, Ca, Ca2+, S, Al, Si and Fe were higher in particles than other components. The chemical marker of carbon plant was EC, and the trace carbonaceous components of carbon plant were EC1 and EC2, which were very different from other carbon emission sources. In the absence of other chemical composition information, eight carbonaceous components can be used to identify the sources of particle. [ABSTRACT FROM AUTHOR]

In the background of carbon neutrality, carbon emissions are basked in the attention. As a significant source of carbon emissions, the emission characteristics of carbon plant should be known. Particulate matter in flue gas was collected in a carbon plant in Tongliao. The chemical components in PM10 and PM2.5 were analyzed, and source profile of carbon plant was established. The results showed that the mass fractions of EC, Ca, Ca2+, S, Al, Si and Fe were higher in particles than other components. The chemical marker of carbon plant was EC, and the trace carbonaceous components of carbon plant were EC1 and EC2, which were very different from other carbon emission sources. In the absence of other chemical composition information, eight carbonaceous components can be used to identify the sources of particle.

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In order to investigate the chemical characteristics of aerosol pollution including PM1 and PM2.5 in Handan, the offline sampling campaign was conducted and the concentrations of total water-soluble inorganic ions (TWSI), carbonaceous components (OC and EC) were analyzed. The average concentrations were 88.5 μg/m3 for PM1 and 122 μg/m3 for PM2.5, and the corresponding ratios of PM1 versus PM2.5 on non-pollution, mild-moderate pollution and heavy pollution were 0.67, 0.70 and 0.77, respectively. TWSI and OC accounted for 43.2% and 15.4% in PM1, 41.8% and 16.0% in PM2.5. Secondary components in PM2.5 and PM1 increased with heavy pollution, SNA (SO42−, NO3− and NH4+) was enriched in PM1 but SOC (Secondary Organic Carbon) was more enriched in PM1–2.5. Furthermore, for evaluating the effect of aerosol feedback the WRF-Chem model was applied to identify the aerosol-radiation interaction of aerosol feedback influence on the PM2.5 concentration and various meteorological factors in Handan. The results indicated that the aerosol radiative effects will result in an average 32.62%(36.18 W/m2) decrease in downward short wave flux at ground surface (SWDOWN), an average 17.52% (39.15 m) and 0.16% (0.44 K) decrease in planetary boundary layer height(PBLH) and surface temperature (T2). The wind speed at 10 m (WS) and relative humidity (RH) will be increased by about 4.16%(0.11 m/s) and 1.89% (0.78%), respectively.

PM2.5 was sampled from January 2017 to May 2018 at an urban, suburban, industrial, and rural sites in Xining. The annual mean of PM2.5 was highest at the urban site and lowest at the rural site, with an average of 51.5 ± 48.9 and 26.4 ± 17.8 μg·m−3, respectively. The average PM2.5 concentration of the industrial and suburban sites was 42.8 ± 27.4 and 37.2 ± 23.7 μg·m−3, respectively. All sites except for the rural had concentrations above the ambient air quality standards of China (GB3095-2012). The highest concentration of PM2.5 at all sites was observed in winter, followed by spring, autumn, and summer. The concentration of major constituents showed statistically significant seasonal and spatial variation. The highest concentrations of organic carbon (OC), elemental carbon (EC), water-soluble organic carbon (WSOC), and water-soluble inorganic ions (WSIIs) were found at the urban site in winter. The average concentration of F− was higher than that in many studies, especially at the industrial site where the annual average concentration of F− was 1.5 ± 1.7 μg·m−3. The range of sulfur oxidation ratio (SOR) was 0.1–0.18 and nitrogen oxidation ratio (NOR) was 0.02–0.1 in Xining. The higher SO42−/NO3− indicates that coal combustion has greater impact than vehicle emissions. The results of the potential source contribution function (PSCF) suggest that air mass from middle- and large-scale transport from the western areas of Xining have contributed to the higher level of PM2.5. On the basis of the positive matrix factorization (PMF) model, it was found that aerosols from salt lakes and dust were the main sources of PM2.5 in Xining, accounting for 26.3% of aerosol total mass. During the sandstorms, the concentration of PM2.5 increased sharply, and the concentrations of Na+, Ca2+ and Mg2+ were 1.13–2.70, 1.68–4.41, and 1.15–5.12 times higher, respectively, than annual average concentration, implying that aerosols were mainly from dust and the largest saltwater lake, Qinghai Lake, and many other salt lakes in the province of Qinghai. Time-of-flight secondary ion mass spectrometry (ToF-SIMS) was utilized to study the surface components of PM2.5 and F− was found to be increasingly distributed from the surface to inside the particles. We determined that the extremely high PM2.5 concentration appears to be due to an episode of heavy pollution resulting from the combination of sandstorms and the burning of fireworks.

In order to survey the seasonal variation of the chemical composition of particulate matter of 2.5 μm or less (PM2.5), PM2.5 was sampled from 8 February 2013 to 31 March 2014 in an industrial area of Chiba Prefecture, Japan. Chemical measurements of the sample included: ionic components (Na+, NH4+, Ca2+, Mg2+, K+, Cl-, NO3- and SO42-), carbonaceous components - organic carbon (OC) and elemental carbon (EC), and water-soluble organic carbon (WSOC). Also, secondary organic carbon (SOC) was measured based using the EC tracer method, and char-EC and soot-EC were calculated from the analytical results. The data obtained were interpreted in terms of temporal variation. Of the overall mean value of PM2.5 mass concentration obtained during the study period, ionic components, OC and EC accounted for 45.3%, 19.7%, and 8.0%, respectively. NO3- showed a unique seasonal distribution pattern due to a dependence on temperature and absolute humidity. It was estimated that an approximate temperature of 14°C, and absolute humidity of 7 g/m3 were critical for the reversible reaction of NH4NO3 (p) ⇋ NH3 (g)+HNO3 (g). The amount of OC and EC contributing to the monthly PM2.5 mass concentration was higher in autumn and winter compared to spring and summer. This result could be attributed to the impact of burning biomass, since WSOC and the ratio of char-EC/soot-EC showed a similar pattern during the corresponding period. From the comparison of monthly WSOC/OC values, a maximum ratio of 83% was obtained in August (summer). The WSOC and estimated SOC levels derived from the EC tracer method correlated (R=0.77) in summer. The high occurrence of WSOC during summer was mainly due to the formation of SOC by photochemical reactions. Through long-term observation of PM2.5 chemical components, we established that the degree to which the abovementioned factors influence PM2.5 composition, fluctuates with seasonal changes.

Daytime and nighttime PM10 samples were collected during winter at an urban site in Southeastern Spain. Samples were subsequently analyzed to determine the concentrations of water-soluble ions, carbonaceous species, and metals. PM10 daytime and nighttime concentrations were 26.1 and 20.6 μg/m3, respectively. This difference may be mainly attributed to the reduction in the number of vehicles during nighttime. Traffic-related components such as EC, Ca and other crustal elements, Cu or Zn, showed statistically significantly higher concentrations during daytime, suggesting that traffic emissions were more relevant than day-to-night differences in meteorological conditions. In contrast, no significant differences between daytime and nighttime levels of secondary inorganic ions (SO42−, NO3− and NH4+) were found. Primary and secondary organic carbon concentrations were estimated using the EC tracer method. As expected, POC levels were greater during the day due to increased vehicle exhaust emissions; conversely, higher SOC concentrations were registered during the nighttime period. This was most likely the result of a significant contribution of nighttime chemistry to the formation of secondary organic aerosols. [ABSTRACT FROM AUTHOR]

PM 2.5 samples were collected daily at the Lin'an regional background station (LA) in Zhejiang, China during 2014–2015 and the major chemical components including organic carbon (OC), elemental carbon (EC) and water-soluble inorganic ions (WSII) were determined. Backward trajectory clustering and potential source contribution function (PSCF) were adopted for identifying the transport pathways and potential source regions of PM 2.5 at LA. The annual mean concentration was 68.9 ± 28.3 μg m −3 , indicating severe pollution in East China. Obvious seasonal variations were found, with highest level in winter and lowest in summer. Carbonaceous aerosols and WSII were the predominant compositions, accounting for 30.7% and 53.5% of PM 2.5 , respectively. Secondary inorganic ions (SO 4 2− , NO 3 − , and NH 4 + ) made a total contribution of 45.2% to PM 2.5 . Heterogeneous formation played a dominant role in SO 4 2− formation and NH 4 + formation promoted NO 3 − formation. Stationary sources played a more important role than mobile sources based on NO 3 − /SO 4 2− ratio of 0.53. Aerosol environment at LA was ammonium-poor and SO 4 2− was only neutralized sufficiently by NH 4 + with the predominant production of (NH 4 ) 2 SO 4 in winter. Four major transport pathways of air masses at LA were found based on trajectory clustering. Air masses from the northwest Gobi areas passing over the heavily polluted regions in North and Central China had the highest levels of PM 2.5 , followed by the air masses from Central China. PSCF results suggested that surrounding areas in the Yangtze River Delta region were major regional origins of PM 2.5 and its major components. Northern region was an important origin for carbonaceous components, and southwestern region was significant for secondary inorganic ions. This study helps understand PM 2.5 characteristics, identify potential source regions and effectively control PM 2.5 in East China. [ABSTRACT FROM AUTHOR]

To investigate the pollution characteristics of carbonaceous components in PM 10 and PM 2.5 of road dust fall and soil dust in Xi'an and enrich their source profiles, samples from five sites of road dust fall and 16 sites of soil dust were collected in Xi'an from April to May 2015. The ZDA-CY01 particulate matter resuspension sampler was used to obtain PM 10 and PM 2.5 samples, and the Model5L-NDIR OC and EC analyzer were used to determine the concentrations of organic carbon (OC) and elemental carbon (EC) in PM 10 and PM 2.5 . The pollution and sources of carbonaceous aerosol in PM 10 and PM 2.5 were investigated by analyzing OC and EC characteristics, ratio, and the principal component analysis statistical model. The results showed that the proportions of OC in PM 10 and PM 2.5 at the various dust fall sites differed, ranging from 6.0% to 19.4% and 7.6% to 29.8%, respectively. The ratios of EC in PM 10 and PM 2.5 at the different dust fall sites were relatively small, accounting for 0.6%-2.2% and 0.2%-3.6% in urban sites, respectively; however, EC was almost undetectable in most peripheral soil dust. The proportions of carbonaceous components in PM 10 and PM 2.5 followed the order of urban road dust fall>external control dust>river beach soil dust>soil dust and urban road dust fall>soil dust>external control dust>river beach soil dust, respectively. OC dominated the carbonaceous aerosols at the different sites, which was relatively low in urban road dust fall. The OC to total carbon (TC) ratios in PM 10 and PM 2.5 at urban road dust fall were 85.2%-95.3% and 87.9%-98.9%, respectively. The OC to TC ratios in PM 10 and PM 2.5 of soil dust were relatively high, exceeding 99%. Carbonaceous components were primarily concentrated in fine particles. The pollution distribution of carbonaceous components in the urban road dust fall sites was consistent, whereas that in the different soil dust sites were quite different. The carbonaceous components in urban road dust fall and soil dust were primarily affected by pollutant source emissions such as biomass burning, coal burning, gasoline, and diesel vehicle exhaust. There were differences in the source contribution rates of carbonaceous aerosols in PM 10 and PM 2.5 .

The pollution characteristics of PM2.5 and its chemical compositions under different air quality grades (HJ 633-2012) were analyzed from January 1 to December 31, 2013, by using the online monitoring data at four representative air quality monitoring sites, and the chemical compositions of sampled PM2.5 in Handan. The results showed that the average annual concentration of PM2.5 was 139 μg m-3 in Handan city in 2013, which was about 4 times of the national Grade II standard (35μg m-3), and the percentages of the number of the days exceeding the national Grade II air quality standard (GB3095-2012) were 74.4%. There were no excellent days, and moderately to severely polluted days accounted for 50% throughout the year. With the deterioration of air quality grades, the mass concentrations of PM2.5 and its chemical compositions were elevated, and the mass concentrations of most chemical compositions increased dramatically when severe pollution occurred except for a few elements. The mass concentrations of elemental carbon (EC) and organic matter (OM) on severely polluted days were approximately 5.9 and 5.5 times those of good days. NO3-/SO42- and OC/EC ratio increase when air quality index (AQI) increased, and peaked in moderately and heavily polluted days, respectively, and slightly fall down under the severely polluted days. The enrichment factors (EF) of all elements had different degree of increase, and the EF of anthropogenic elements were elevated consistent with the increasing of the AQI, while the elements from crustal sources did not show the obvious change. [ABSTRACT FROM AUTHOR]

Daily PM 2.5 samples were obtained at the site of East China University of Science and Technology (ECUST) in urban Shanghai during 2009–2010 and 2011–2012. The temporal variations of PM 2.5 and its chemical compositions including secondary inorganic aerosol (SIA) and carbonaceous components were studied. The concentrations of PM 2.5 were (94.04 ± 52.17) μg/m 3 and (68.44 ± 41.57) μg/m 3 in 2009 and 2012, respectively. The concentrations and contributions of SIA to PM 2.5 were significantly higher in 2012 than those in 2009. Sulfate took up above 50% of SIA in 2009 and the corresponding value decreased to 41% in 2012. The increasing trend of NO 3 − /SO 4 2 − mass ratio implied that the contributions of mobile sources were more and more important. The molar ratios of [NH 4 + ]/(2[SO 4 2 − ] + [NO 3 − ]) were 0.57 and 0.70, lower than 1, which demonstrated that most aerosol samples were ammonium-poor. But the neutralization process of ammonium might affect the formation of sulfate and nitrate, which was indicated by the strong correlation between [NH 4 + ]–[SO 4 2 − ] and [NH 4 + ]–[NO 3 − ]. The average molar ratio of ammonium to sulfate was 1.74 in 2009, so there was not enough ammonium to neutralize sulfate sufficiently. The higher value of 2.30 in 2012 indicated that sulfate was sufficiently neutralized by ammonium and the predominant production was (NH 4 ) 2 SO 4 . Aerosol samples had higher char-EC/soot-EC ratios and lower OC/EC ratios in 2009 than those of samples in 2012. The higher K + /OC values demonstrated that biomass burning made important contributions to carbonaceous components in both 2009 and 2012. All backward trajectories were grouped into four clusters, mainly from the Northwest, the Circum-Bohai-Sea Region (CBSR), the Southwest and the Southeast. The cluster from the Northwest was the most polluted pathway in 2009, while the cluster from the CBSR had more effects in 2012. PSCF model for PM 2.5 and carbonaceous components except soot-EC suggested that the Yangtze River Delta Region (YRDR) made significant contributions by short-range transportation in 2009 and 2012. The Northwest, the CBSR and the Pearl River Delta Region (PRDR) were also the potential source areas. However, the source pattern of soot-EC was significantly different from those of other carbonaceous components. [ABSTRACT FROM AUTHOR]

The 24-h PM 2.5 samples were collected at the site of East China University of Science and Technology (ECUST) in Shanghai from 2011 to 2012, representing winter, spring, summer and autumn, respectively. And PM 2.5 and its chemical components including organic carbon (OC), elemental carbon (EC), water-soluble organic carbon (WSOC), humic-like substance carbon (HULIS-C) and water-soluble ions were analyzed. The results suggested that the average PM 2.5 concentrations were (70.35 ± 43.75) μg/m 3 , (69.76 ± 38.67) μg/m 3 , (51.26 ± 28.25) μg/m 3 and (82.37 ± 48.70) μg/m 3 in winter, spring, summer and autumn, respectively. Secondary inorganic ions (sulfate, nitrate and ammonium) were the dominant pollutants of PM 2.5 in the four seasons. Total carbon (TC) was an important component explaining above 15% of PM 2.5 . OC/EC ratios were all above 2 ranging from 4.31 to 6.35; particularly in winter it reached the highest 6.35 which demonstrated that secondary organic carbon (SOC) should be a significant composition of PM 2.5 . The SOC calculated based on the OC/EC ratio method had stronger correlation with WSOC in summer and autumn (summer: R 2 = 0.73 and autumn: R 2 = 0.75). The HULIS-C and SOC most significantly correlated in autumn (R 2 = 0.83). The data showed that PM 2.5 atmospheric aerosols were more acidic in autumn and the concentrations of PM 2.5 and its chemical components were much higher. Factor analysis (FA), cluster analysis of air mass back trajectories, potential source contribution function (PSCF) model and concentration weighted trajectory (CWT) model were used to investigate the transport pathways and identify potential source areas of PM 2.5 in different seasons. FA identified various sources of PM 2.5 : secondary aerosol reactions, the aged sea salts and road dusts. The results of cluster analysis, PSCF model and CWT model demonstrated that the local sources in the Yangtze River Delta Region (YRDR) made significant contributions to PM 2.5 . During winter and autumn long-time transport from the Circum-Bohai-Sea Region (CBSR) and northwestern China including the Inner Mongol had adverse effects. [ABSTRACT FROM AUTHOR]

In order to survey the seasonal variation of the chemical composition of particulate matter of 2.5 μm or less (PM2.5), PM2.5 was sampled from 8 February 2013 to 31 March 2014 in an industrial area of Chiba Prefecture, Japan. Chemical measurements of the sample included: ionic components (Na+ NH4+, Ca2+ Mg2+ K+, Cl-, NO3 - and SO4 2-), carbonaceous components - organic carbon (OC) and elemental carbon (EC), and water-soluble organic carbon (WSOC). Also, secondary organic carbon (SOC) was measured based using the EC tracer method, and char-EC and soot-EC were calculated from the analytical results. The data obtained were interpreted in terms of temporal variation. Of the overall mean value of PM2.5 mass concentration obtained during the study period, ionic components, OC and EC accounted for 45.3%, 19.7%, and 8.0%, respectively. NO3 - showed a unique seasonal distribution pattern due to a dependence on temperature and absolute humidity. It was estimated that an approximate temperature of 14° C, and absolute humidity of 7 g/m³ were critical for the reversible reaction of NH4NO3 (p) ⇋ NH3 (g) + NO3 (g). The amount of OC and EC contributing to the monthly PM2.5 mass concentration was higher in autumn and winter compared to spring and summer. This result could be attributed to the impact of burning biomass, since WSOC and the ratio of char-EC/ soot-EC showed a similar pattern during the corresponding period. From the comparison of monthly WSOC/OC values, a maximum ratio of 83% was obtained in August (summer). The WSOC and estimated SOC levels derived from the EC tracer method correlated (R=0.77) in summer. The high occurrence of WSOC during summer was mainly due to the formation of SOC by photochemical reactions. Through long-term observation of PM2.5 chemical components, we established that the degree to which the above-mentioned factors influence PM2.5 composition, fluctuates with seasonal changes. [ABSTRACT FROM AUTHOR]

People spend the majority of their time indoors and the composition and toxicity of indoor particles is very complex and present significant differences comparing with outdoor aerosols. Consequently, ambient particles cannot represent a real exposure. The aim of this work was to determine the daily exposure and the daily inhaled dose to particle components of elders living in Elderly Care Centers. A questionnaire was applied to 193 institutionalized elders in order to achieve their daily time pattern and to define the micro-environments where PM 10 and its components (carbonaceous components and trace elements) were assessed. Daily exposure was calculated by integrating the elder's time spend in each micro-environment and the concentration of the pollutants for the period of interest. This parameter, together with the inhalation rate and the standard body weight, were used to calculate the daily inhaled dose. PM 10 daily exposure and daily inhaled dose ranged between 11 – 16 μg m −3 and 20 × 10 −3 – 28 × 10 −3 μg kg −1 , respectively. This work not only allowed a fully quantification of the magnitude of the elders exposure, but also showed that the assessment of the integrated exposure to PM components is determinant to accomplish the dose inhaled by elders living in ECCs. [ABSTRACT FROM AUTHOR]

PM2.5 and total suspended particulate (TSP) samples were collected from June to September 2010 at Qinghai Lake, northeastern Tibetan Plateau. The concentrations of major water-soluble ions, 10 elements, elemental carbons (ECs) and organic carbons (OCs) were quantified. Mass concentrations of PM2.5 and TSP were 21.27±10.70μgm−3 and 41.47±20.25μgm−3, respectively, and the mean ratio of PM2.5/TSP was 0.51. The greatest anion and cation in both PM2.5 and TSP samples were SO4 2− and Ca2+, respectively. Crustal elements, such as Ca, Fe and K, were the main elements in our aerosol samples, and their enrichment factors (EFs) were lower than 10. EFs for Pb, As, and Zn were greater than 10, indicating that they were influenced by anthropogenic sources. EC concentrations were 0.33±0.17μgm−3 and 0.47±0.28μgm−3, whereas OC concentrations were 1.49±0.63μgm−3 and 2.30±0.95μgm−3 in PM2.5 and TSP, respectively. Based on the calculated ratios of EC/TC and K+/EC, most of the ECs were found to be related to biomass burning emissions. Because of the pollution from local sources, the ratios of OC/EC were 4.77±1.32 and 5.23±1.39 in PM2.5 and TSP, respectively, which were lower than those of other remote sites. Salt particles produced by the salty lake reacted with acid gases and caused most of the nitrates and a small fraction of sulfate to be distributed in coarse mode; Cl deficit was also observed in our aerosol samples. Results of backward trajectories and correlation analysis show that the concentrations of SO4 2−, OCs, As, Pb, and Zn, were influenced by the long-distance transport from eastern China. [ABSTRACT FROM AUTHOR]

In order to investigate the chemical characteristics of aerosol pollution including PM1 and PM2.5 in Handan, the offline sampling campaign was conducted and the concentrations of total water-soluble inorganic ions (TWSI), carbonaceous components (OC and EC) were analyzed. The average concentrations were 88.5 μg/m3 for PM1 and 122 μg/m3 for PM2.5, and the corresponding ratios of PM1 versus PM2.5 on non-pollution, mild-moderate pollution and heavy pollution were 0.67, 0.70 and 0.77, respectively. TWSI and OC accounted for 43.2% and 15.4% in PM1, 41.8% and 16.0% in PM2.5. Secondary components in PM2.5 and PM1 increased with heavy pollution, SNA (SO42−, NO3− and NH4+) was enriched in PM1 but SOC (Secondary Organic Carbon) was more enriched in PM1–2.5. Furthermore, for evaluating the effect of aerosol feedback the WRF-Chem model was applied to identify the aerosol-radiation interaction of aerosol feedback influence on the PM2.5 concentration and various meteorological factors in Handan. The results indicated that the aerosol radiative effects will result in an average 32.62%(36.18 W/m2) decrease in downward short wave flux at ground surface (SWDOWN), an average 17.52% (39.15 m) and 0.16% (0.44 K) decrease in planetary boundary layer height(PBLH) and surface temperature (T2). The wind speed at 10 m (WS) and relative humidity (RH) will be increased by about 4.16%(0.11 m/s) and 1.89% (0.78%), respectively. [ABSTRACT FROM AUTHOR]

To explore the main sources of PM 2.5 and the characteristics of seasonal differences in Zhengzhou, PM 2.5 sampling was conducted in 2019 and the concentrations of inorganic water-soluble ions, carbon components, and various elements were analyzed. Results showed that the average mass concentration of PM 2.5 in 2019 was (67.0±37.2) μg ·m -3 with the highest concentration in winter and the lowest in summer. The main components of PM 2.5 were nitrate, ammonium, sulfate, organic matter, crustal matter, and elemental carbon. In spring and autumn, PM 2.5 was greatly affected by crustal matter and elemental carbon, and In summer, concentrations were mainly affected by sulfate. In winter, the concentrations of organic matter and nitrate increased significantly, produced by photochemical reactions in summer and aqueous-phase reactions under high humidity in winter. Carbonaceous aerosols were greatly influenced by automobile exhaust emission, coal combustion, and biomass combustion. Source apportionment showed that secondary sources were the greatest contributors in all four seasons, particularly in in winter (56.5%). Among the primary sources, the proportion of dust in spring (15.2%) and autumn (11.4%) was slightly higher, and the contribution of motor vehicle pollution was the largest (12.3%) in summer. In winter, PM 2.5 was greatly affected by coal combustion (13.2%). From 2014 to 2019, PM 2.5 in Zhengzhou increased annually under the influence of secondary sources. The contribution of industrial sources, biomass combustion sources, and coal combustion sources exhibited a downward trend over this period.

PM2.5 was sampled from January 2017 to May 2018 at an urban, suburban, industrial, and rural sites in Xining. The annual mean of PM2.5 was highest at the urban site and lowest at the rural site, with an average of 51.5 ± 48.9 and 26.4 ± 17.8 μg·m−3, respectively. The average PM2.5 concentration of the industrial and suburban sites was 42.8 ± 27.4 and 37.2 ± 23.7 μg·m−3, respectively. All sites except for the rural had concentrations above the ambient air quality standards of China (GB3095-2012). The highest concentration of PM2.5 at all sites was observed in winter, followed by spring, autumn, and summer. The concentration of major constituents showed statistically significant seasonal and spatial variation. The highest concentrations of organic carbon (OC), elemental carbon (EC), water-soluble organic carbon (WSOC), and water-soluble inorganic ions (WSIIs) were found at the urban site in winter. The average concentration of F− was higher than that in many studies, especially at the industrial site where the annual average concentration of F− was 1.5 ± 1.7 μg·m−3. The range of sulfur oxidation ratio (SOR) was 0.1–0.18 and nitrogen oxidation ratio (NOR) was 0.02–0.1 in Xining. The higher SO42−/NO3− indicates that coal combustion has greater impact than vehicle emissions. The results of the potential source contribution function (PSCF) suggest that air mass from middle- and large-scale transport from the western areas of Xining have contributed to the higher level of PM2.5. On the basis of the positive matrix factorization (PMF) model, it was found that aerosols from salt lakes and dust were the main sources of PM2.5 in Xining, accounting for 26.3% of aerosol total mass. During the sandstorms, the concentration of PM2.5 increased sharply, and the concentrations of Na+, Ca2+ and Mg2+ were 1.13–2.70, 1.68–4.41, and 1.15–5.12 times higher, respectively, than annual average concentration, implying that aerosols were mainly from dust and the largest saltwater lake, Qinghai Lake, and many other salt lakes in the province of Qinghai. Time-of-flight secondary ion mass spectrometry (ToF-SIMS) was utilized to study the surface components of PM2.5 and F− was found to be increasingly distributed from the surface to inside the particles. We determined that the extremely high PM2.5 concentration appears to be due to an episode of heavy pollution resulting from the combination of sandstorms and the burning of fireworks. [ABSTRACT FROM AUTHOR]

Copper helps to accelerate heat transfer during the braking process, allowing the brake materials to produce a stable coefficient of friction (COF), which in turn reduces wear loss and braking noise. However, its properties are also quite harmful to aquatic organisms. Finding a suitable replacement that fits all functions of copper for brake materials is not an easy feat. In this paper, six different carbonaceous components (coke, carbon black, carbon fiber, artificial graphite, natural graphite and expanded graphite) were substituted for copper in non-asbestos organic (NAO) friction materials. The hardness, thermal conductivity and tribological behaviors of these copper-free NAO friction materials were examined. Experimental results indicate that carbonaceous components improve lubrication and assist the friction composites with generating friction layers on the worn surface. Specimens containing coke, carbon black or carbon fiber exhibit broken friction layers, whereas specimens containing artificial graphite, natural graphite or expanded graphite exhibit quite adherent and smooth friction layers. Among all the copper-free carbon containing specimens, the specimen containing expanded graphite appears to be the best choice. It has the highest thermal conductivity, a relatively low wear loss and a relatively high and stable COF. [ABSTRACT FROM AUTHOR]

Taking the typical heavy air pollution process in Yangquan from December 26, 2018 to January 20, 2019 as an example, the characteristics and cause analysis of heavy air pollution in a mountainous city in winter were analyzed in this study. The results showed that fine particle mass (PM 2.5 ) was the primary pollutant during the heavy pollution period. The water-soluble ions and carbonaceous components were the main components of PM 2.5 . The secondary ions of SO 4 2- , NO 3 had the lager contribution to water-soluble ions (87.7%), and the secondary organic carbon (SOC) was the main component of the carbonaceous components (71.6%). The concentration of the secondary ions during the heavy pollution period increased by 5.3 times compared to levels before the heavy pollution period, and was an important component resulting in the fast increase of PM - , and NH 4 + had the lager contribution to water-soluble ions (87.7%), and the secondary organic carbon (SOC) was the main component of the carbonaceous components (71.6%). The concentration of the secondary ions during the heavy pollution period increased by 5.3 times compared to levels before the heavy pollution period, and was an important component resulting in the fast increase of PM 2.5 . An analysis of meteorological conditions showed that PM 2.5 and its main components had a significantly positive relationship with humidity and a significantly negative relationship with wind speed. And that pollution became stronger with an increase in humidity and a decrease in wind speed. The typical meteorological characteristics of mountainous cities are high relative humidity and large temperature variations, which can accelerate the formation of secondary pollutants and are the main reasons for the rapid aggravation of PM 2.5 . In addition, the lower average wind speed caused by the relatively closed terrain in mountainous cities makes the diffusion conditions of air pollutants relatively poor, which is one of the reasons for the accumulation of pollutants. The source apportionment results showed that the secondary sources (46.0%) were the most important source of PM 2.5 , followed by coal combustion (32.6%), vehicle exhaust (19.8%), and fugitive dust (1.6%). Therefore, mountainous cities should pay more attention to controlling secondary components, especially secondary ions.

As flue gas desulfurization (FGD) was one of the most important purification processes of coal-fired boilers, we selected four boilers, which were equipped with wet limestone, furnace calcium injection, ammonia-based, and double-alkali FGDs, to research the influence of FGDs on the flue particulate matter (PM). The flue PM before and after the FGD were sampled using laboratory resuspension and dilution tunnel sampling methods, respectively, and the PM was analyzed for its chemical composition (i.e., ions, elements, and carbon). The results showed that the types of desulfurizers could influence the composition of the flue PM. After passing through the wet limestone, ammonia-based, and double-alkali FGDs, the proportion of Ca, NH 4 + , and Na in PM 2.5 increased from 5.1% to 24.8%, from 0.8% to 7.3%, and from 0.9% to 1.7%, respectively. The influence of wet and dry FGDs on the flue PM were different. The fraction of ions in the PM emitted from the wet FGD were higher than those from the dry FGD. The proportion of SO 4 2- in the flue PM 2.5 increased from 2.0% and 6.7% to 9.6% and 11.9% using the wet limestone and ammonia-based FGDs, respectively, and Cl - emitted from the dry FGD boiler was richer in crustal elements, such as Al, Si, and Fe, than that from the wet FGDs. The wet FGDs also effected the carbonaceous components of the flue PM. After passing through the wet limestone and ammonia-based FGDs, the proportion of elemental carbon in the flue PM 2.5 declined after the wet FGDs. The PM 2.5 emitted from the dry FGD boiler was richer in crustal elements, such as Al, Si, and Fe, than that from the wet FGDs. The wet FGDs also effected the carbonaceous components of the flue PM. After passing through the wet limestone and ammonia-based FGDs, the proportion of elemental carbon in the flue PM 2.5 decreased from 6.1% to 0.9% and from 3.6% to 0.7% respectively, but the organic carbon content did not decrease.

Objectives: To explore the health effects of indoor/outdoor carbonaceous compositions in PM 2.5 on pulmonary function among healthy students living in the local university campus., Methods: Daily peak expiratory flow (PEF) and forced expiratory volume in 1 second (FEV 1 ) were measured among 37 healthy students in the morning and evening for four two-week periods. Concurrent concentrations of indoor and outdoor PM 2.5 (particulate matter with an aerodynamic diameter ≤ 2.5μm), carbonaceous components in PM 2.5 , ambient temperature, and relative humidity in the study area were also obtained. Mixed-effects model was applied to evaluate the associations between carbonaceous components and lung function. Different lags for the carbonaceous components were investigated., Results: In single-pollutant model, a 10 μg/m 3 increase of indoor and outdoor EC (elemental carbon) associated with -3.93 (95% CI : -6.89, -0.97) L/min and -3.21 (95% CI : -5.67, -0.75) L/min change in evening PEF at lag 0 day, respectively. Also, a 10 μg/m 3 increase of indoor and outdoor POC (primary organic carbon) concentration was significantly associated with -5.82 (95% CI : -10.82, -0.81) L/min and -7.32 (95% CI : -12.93, -1.71) L/min change of evening PEF at lag 0 day. After adjusting total mass of PM 2.5 , indoor EC consistently had a significant adverse impact on evening PEF and FEV 1 at lag3 day and a cumulative effect at lag0-3 day., Conclusions: This study suggests that carbonaceous components in PM 2.5 indeed have impacts on pulmonary function among healthy young adults especially on evening PEF. Thus, the local mitigation strategies on pollution are needed.

There are few analyses on the components of particulate matter emitted from waste incineration plants. In past studies, analyses of particle size distribution characteristics of the components were mainly targeted at particles with larger particle sizes. An electrical low pressure impactor (ELPI) was used in this study to collect the particulate matter emitted from a waste incineration plant, and the elements and carbonaceous components of these samples were analyzed. The particle size characteristics of organic carbon (OC), elemental carbon (EC), and heavy metal elements in 14 particle size segments were analyzed and composition profiles of elements and carbonaceous components of PM 1 , PM 2.5 , and PM 10 from the waste incineration plant were established to provide a reference for refined source apportionment research. The results showed that the main components of the waste incineration plant included Al, Si, S, Ca, Cr, Fe, OC, EC, etc. OC and Ca were dominating components, and mass fractions of these components in the PM 2.5 profile were 10.15% and 12.37%, respectively. The contents of heavy metals were ranked as Cr > Pb > Zn > Mn > Cu > Cd > Ni, and the mass fractions of Cr and Pb in PM 2.5 amounted to 1.83% and 0.74%, respectively. OC in the range of 2.39-3.99 and 6.68-9.91 μm accounted for 15.02% and 20.45% of the total OC content, respectively, and the content of OC in fine particles was higher than that in coarse particles. The content of EC in fine particles was much higher than that in coarse particles, and it accounted for 14.8% in the 0.382-0.613 μm particle size. Heavy metal elements such as Cr, Mn, Ni, Cu, Zn, Cd, and Pb were mainly concentrated in the fine particles.

China is one of the most important contributors to the global burden of carbonaceous aerosols, of which domestic coal combustion occupies a large fraction. Uncertainty in the emission factors (EFs) directly influences the accuracy of corresponding emission inventories. In the present study, based on domestic burning tests with a dilution sampling system, nine size-segregated particle classes emitted from the burning of three kinds of honeycomb coals (under flaming and smoldering burning conditions) and four kinds of chunk coals, including bituminous and lignite, were collected via a cascade impactor (FA-3). Organic and elemental carbon (OC and EC, respectively) were analyzed using the thermal-optical method. The EFs of particulate matter (PM), OC, and EC for nine size ranges were obtained. For honeycomb coals, the EFs of OC and EC in PM 2.1 were 0.07 g·kg -1 and 0.002 g·kg -1 , respectively, under flaming burning conditions and 0.10 g·kg -1 and 0.001 g·kg -1 , respectively, under smoldering burning conditions. Carbonaceous particles exhibited higher EFs under flaming burning conditions. For chunk coals, the EFs of OC and EC in PM 2.1 were 1.4 g·kg -1 and 0.02 g·kg -1 , respectively, which are about one magnitude higher than those for honeycomb coal burning. Particulate matter and its associated carbonaceous components preferred to concentrate in fine particles. The EFs of carbonaceous components peaked at the size of ≤ 0.43 μm and 0.43-0.65 μm for honeycomb coal burning and chunk coal burning, respectively.

Organic carbon (OC) and elemental carbon (EC) emission factors from 27 State 3-5 light-duty gasoline vehicles (LDGVs) were tested in this study using a CVS (Constant Volume Sampling) system on a dynamometer. The influences of start conditions, driving cycles, and fuel injection technologies on the OC and EC emissions were analyzed. The results show that the OC emission factors of the tested State 3 to 5 LDGVs were (2.09±1.03), (1.59±0.78), and (0.75±0.31) mg·km -1 , respectively, and the EC emission factors were (1.98±1.42), (1.57±1.80), and (0.65±0.49) mg·km -1 . Both OC and EC emissions significantly decreased with the promotion of emission standards. The OC/EC ratios were 1.54±0.92, 1.53±0.91, and 1.47±0.66, respectively. OC1, OC2, EC1, and EC2 were the most important carbonaceous components from LDGVs, accounting for 15%, 20.6%, 22.2%, and 21.7%, respectively. OC and EC emission factors under cold-start conditions were 1.4 and 1.8 times those under hot-start conditions. OC and EC emission factors for highway cycles were 2 and 4 times those for urban cycles. OC emission factors from GDI (Gasoline Direct Injection) engines were close to those from PFI (Port Fuel Injection) engines. However, their EC emission factors were 1.7 times those from PFI engines. With the increasing popularity of GDI engines in LDGV fleets in China, the EC emissions from these engines should be paid more attention in the future.

PM 2.5 samples of four seasons were collected from Nov. 2014 to Aug. 2015 at the site of Shengsi island in Zhoushan islands. Mercury (Hg) and speciated mercury concentrations in PM 2.5 samples were measured by Atomic Fluorescence Spectrometry (AFS-9130, China) after digestion with CEM Mars Xpress (PyNN Corporation, USA). The concentrations of organic carbon (OC) and elemental carbon (EC) in PM 2.5 samples were determined by thermal/optical carbon analyzer (DRI, USA). The results showed that the daily concentrations of PM 2.5 -bounded mercury (PBM) ranged from 0.02 to 1.25 ng·m -3 . Moreover, the mass content of PBM was (12.46±18.79) μg·g -1 , which was higher than those in continental cities. ANOVA analysis result suggested that the highest average mass concentrations of PBM occurred in fall, sequentially followed by spring, winter and summer. Higher concentrations of PBM were in fall and spring, which might be related to biomass burning. In addition, RPM took the highest fraction of 53.1% in PBM, followed by HPM (27.3%) and EPM (19.7%), which might be resulted from the complicated composition of marine aerosols. The strong correlations among OC, EC and PBM indicated that carbonaceous composition may affect the transport of Hg in the atmosphere. The ratio of OC/EC represents atmospheric photo-oxidation capacity, so the positive correlation between OC/EC ratio and HPM indicated that HPM was resulted from atmospheric gas-particle transformation. The negative correlation between Char-EC/soot-EC and mercury species indicated that the atmospheric particle-bounded mercury might come mainly from the input of external mercury sources.