Chemical Characterization Of PM2 Research Articles

Chemical characteristics of PM2.5 during summer at a background site of the Yangtze River Delta in China

With rapid economic development and urbanization, particular attention has been paid to atmospheric chemical studies in the Yangtze River Delta in China. PM2.5 samples were collected by a MiniVol™ air sampler in summer time at a background site of the Yangtze River Delta in China. Carbonaceous components, i.e., OC and EC, levoglucosan and water-soluble inorganic ions, including sulfate, nitrate, ammonium, etc., were quantified. The average concentration of PM2.5 in summer at Lin'an was 30.19±8.86μgm−3, lower than previous studies reported, confirming that air pollution in China is improving, e.g., by emission control measures and subsequent reduction in PM emissions in China. Investigating the relationship among sulfate, nitrate and ammonium showed that SO42− existed as (NH4)2SO4, while NO3− may have been present as NaNO3 and KNO3. Based on molecular tracers, synoptic data as well as air mass back trajectory analysis, it was revealed that regional transport and stable synoptic conditions both play an important role in controlling the variations of aerosol chemical components. The comparison of chemical species between clean and hazy days showed that secondary organic and inorganic aerosols have different production processes. Secondary organic carbon (SOC) was much more important during clean days, while secondary inorganic aerosol species were readily produced and consequently became more important during polluted periods in Lin'an during summer time.

Effects of Seasonality and Transport Route on Chemical Characteristics of PM2.5 and PM2.5-10 in the East Asian Pacific Rim Region

ABSTRACTThis study investigated seasonal variation and transport routes of PM2.5 and PM2.5-10 associated metallic elements in the western coastal area of southern Taiwan. Particle sampling was conducted from March 2009 to February 2010. Sixteen metallic elements in PM2.5 and PM2.5-10 samples were determined by ICP-AES and ICP-MS. Multiple approaches, backward trajectory analysis, enrichment factors (EFc), and principle component analysis (PCA), were used to identify the potential sources of the metallic elements. Analysis of the temporal distribution revealed seasonal peaks for most of the trace elements in PM2.5 and PM2.5-10 during winter season and the major elements in PM2.5-10 during the autumn season. The EFc confirmed that the main contributors of Cu, As, Zn, Pb, Cd, and Se were anthropogenic sources. PCA suggested traffic emissions, coal, and heavy oil combustion from both local and neighboring areas, as the major anthropogenic contributors at the sampling site. Backward trajectory analysis, demonstrated different chemical characteristics between the northeast (winter originating in China) and southwest monsoon (summer, from the Southeast Asia). Even in the same season, route-dependent effects of long-range transport in metallic concentrations and total excess cancer risk (ECR) of health-related metals were observed

Chemical Characteristics of PM2.5 during a 2016 Winter Haze Episode in Shijiazhuang, China

ABSTRACTTo better understand the chemical characteristics and the potential source regions of PM2.5 measured from 18 January until 22 January 2016 in Shijiazhuang, China, PM2.5 was measured continuously and integrated daily sampling using mid-volume samplers was conducted at the three sites. The mean concentration of PM2.5 at the three sites reached 113, 131 and 119 µg m–3 during the sampling period, the higher concentrations occurred at early morning and noon, similar variation trends were found in the three sites. The concentrations of OC were higher than EC at three sampling sites and the OC/EC ratios ranged from 9.09 to 12.4 with a daily mean value of 10.8 during a haze pollution episode (HPE), which suggested that carbonaceous compositions might be from same source. The total concentration of water soluble inorganic ions (WSII) at the sites ranged from 72.2 to 100.0 µg m–3 with a mean of 84.3 µg m–3. The dominant species were NO3–, SO42–, NH4+, Cl–, accounting for 88.4% of the mean PM2.5 WSII mass. The most abundant measured element was Na with average mass concentrations of 41.5, 37.0, and 38.1 µg m–3 during the HPE. Relative humidity during HPE was higher than during clean days with average values of 70.1% and 60.2%, suggesting that high relative humidity and low wind speed favored formation of secondary inorganic ions and accelerated hygroscopic growth. The Hybrid Single Particle Lagrangian Integrated Trajectory (HYSPLIT) and a potential source contribution function (PSCF) analysis were used to assess the data. Back-trajectories for the three sites identified similar transport pathways. PSCF analysis showed a significant regional impact on PM2.5 at Shijiazhuang during the polluted period. The potential source areas for PM2.5 in Shijiazhuang were the Beijing-Tianjin region and Shandong Province. The results of the present study show the need for the development of PM2.5 control measurements on a regional scale.

Chemical Characteristics of PM2.5 during 2015 Spring Festival in Beijing, China

Air pollution especially of PM_(2.5) pollution is a serious problem in Beijing. In order to quantify the effect of a festival in which pollution was expected to be reduced, we collected and analyzed PM_(2.5) samples in urban Beijing during the 2015 Spring Festival (from February 9^(th) to March 6^(th) 2015). We divided the sampling period into three phases: non-haze, haze and firework days. The average concentration of PM_(2.5) was highest on firework days at 248.9 μg m^(-3), followed by haze days (199.9 μg m^(-3)) and non-haze days (90.8 μg m^(-3)). The air quality of non-haze days during the holiday was better than that during non-holiday periods. Secondary inorganic ions (SO_4^(2-), NO_3^- and NH_4^+) were enriched on the haze days, while those on firework days contained large amounts of Cl^- and K^+, but small amounts of NO_3^- and NH_4^+. Ratios of NO_3^-/SO_4^(2-), SO_4^(2-)/K^+ and Cl^-/K^+ effectively distinguished the characteristics of PM_(2.5) between firework events and haze days. Ion balance calculations indicated that the acidity of PM_(2.5) from firework days was higher than that from haze and non-haze days. A method using enrichment factors (EF) found that crustal elements (EF ＜ 10 on all three types of days) included Ca, Al, Fe, Na, Co, Ni, P, Ti, and V; firework elements (EF ＞ 10 on firework days, significantly higher than haze days) were made up of Ba, Cr, Cu, Mg, Pb, S, Si, and Zn; common anthropogenic pollution elements (EF ＞ 10 in all three types of days) were As, Cd, Cu, Pb, S, Sb, Zn. Differences in chemical characteristics indicated that holidays such as the Spring Festival can affect air pollution patterns in two ways: a decrease in the population and vehicles but an increase in activities such as firework displays.

Indoor/Outdoor Air Quality Assessment at School near the Steel Plant in Taranto (Italy)

This study aims to investigate the air quality in primary school placed in district of Taranto (south of Italy), an area of high environmental risk because of closeness between large industrial complex and urban settlement. The chemical characterization of PM2.5 was performed to identify origin of pollutants detected inside school and the comparison between indoor and outdoor levels of PAHs and metals allowed evaluating intrusion of outdoor pollutants or the existence of specific indoor sources. The results showed that the indoor and outdoor levels of PM2.5, BaP, Cd, Ni, As, and Pb never exceeded the target values issued by World Health Organization (WHO). Nevertheless, high metals and PAHs concentrations were detected especially when school were downwind to the steel plant. TheI/Oratio showed the impact of outdoor pollutants, especially of industrial markers as Fe, Mn, Zn, and Pb, on indoor air quality. This result was confirmed by values of diagnostic ratio as B(a)P/B(g)P, IP/(IP + BgP), BaP/Chry, and BaP/(BaP + Chry), which showed range characteristics of coke and coal combustion. However, Ni and As showedI/Oratio of 2.5 and 1.4, respectively, suggesting the presence of indoor sources.

Influence of fireworks displays on the chemical characteristics of PM2.5 in rural and suburban areas in Central and East China

To explore the spatial and chemical characteristics of PM2.5 pollution and the influence of fireworks displays on PM2.5 and its chemical components in rural areas in Central and East China, PM2.5 samples were collected at three rural sites and one suburban site in Henan and Shandong provinces during the 2016 Chinese New Year, and the chemical composition of PM2.5, including water-soluble inorganic ions (WSIIs), organic carbon (OC), elemental carbon (EC), water-soluble organic carbon (WSOC) and trace elements (TEs) was analysed. The concentrations of PM2.5 at the four sites were significantly higher than the Grade I national standard of 35μg/m3, indicating serious PM2.5 pollution in rural and suburban areas. The contributions of secondary WSIIs to total WSIIs at the four sites were lower than in urban areas. The TEs in XP and LC were significantly enriched in PM2.5. A significant difference was found in the main chemical compositions of different sites. Fireworks displays directly increased the concentrations of PM2.5 and many chemicals, especially K+, Cl−, K, Cl, S, Cu and Sr, and concentrations of NO3− and NH4+ ions peaked after the fireworks period in the three rural sites, indicating the influence of firecrackers on the secondary formation of the precursors of NO2. The ratio of WSOC/OC decreased during fireworks displays, indicating the direct influence of firecrackers on water insoluble organic matter. Fireworks-related ions were a key component of the aerosol at the four sites during fireworks displays, accounting for 28–38% of the total measured species.

Chemical characterization of PM1.0 aerosol in Delhi and source apportionment using positive matrix factorization.

Fine aerosol fraction (particulate matter with aerodynamic diameter <= 1.0μm (PM)1.0) over the Indian Institute of Technology Delhi campus was monitored day and night (10h each) at 30m height from November 2009 to March 2010. The samples were analyzed for 5 ions (NH4+, NO3-, SO42-, F-, and Cl-) and 12 trace elements (Na, K, Mg, Ca, Pb, Zn, Fe, Mn, Cu, Cd, Cr, and Ni). Importantly, secondary aerosol (sulfate and nitrate) formation was observed during dense foggy events, supporting the fog-smog-fog cycle. A total of 76 samples were used for source apportionment of PM mass. Six factors were resolved by PMF analyses and were identified as secondary aerosol, secondary chloride, biomass burning, soil dust, iron-rich source, and vehicular emission. The geographical location of the sources and/or preferred transport pathways was identified by conditional probability function (for local sources) and potential source contribution function (for regional sources) analyses. Medium- and small-scale metal processing (e.g. steel sheet rolling) industries in Haryana and National Capital Region (NCR) Delhi, coke and petroleum refining in Punjab, and thermal power plants in Pakistan, Punjab, and NCR Delhi were likely contributors to secondary sulfate, nitrate, and secondary chloride at the receptor site. The agricultural residue burning after harvesting season (Sept-Dec and Feb-Apr) in Punjab, and Haryana contributed to potassium at receptor site during November-December and March 2010. The soil dust from North and East Pakistan, and Rajasthan, North-East Punjab, and Haryana along with the local dust contributed to soil dust at the receptor site, during February and March 2010. A combination of temporal behavior and air parcel trajectory ensemble analyses indicated that the iron-rich source was most likely a local source attributed to emissions from metal processing facilities. Further, as expected, the vehicular emissions source did not show any seasonality and was local in origin.

Prevention and control of air pollution needs to strengthen further study on health damage caused by air pollution

Heath issues caused by air pollution such as particulate matter (PM) are much concerned and focused among air, water and soil pollutions because human breathe air for whole life span. Present comments will review physical and chemical characteristics of PM2.5 and PM10; Dose-response associations of PM10, PM2.5 and their components with mortality and risk of cardiopulmonary diseases, early health damages such as the decrease of lung functions and heart rate variability, DNA damage; And the roles of genetic variations and epigenetic changes in lung functions and heart rate variability, DNA damage related to PMs and their components. This comments list some limitations and perspectives about the associations of air pollution with health.

Characteristics of air pollutants at near and far field regions of a national highway located at an industrial complex

This paper presents the characterization of air quality monitored at near field region (NFR) and far field region (FFR) of a national highway located at an industrial complex. The pollutants such as PM10, SO2 and NO2 were monitored in two campaigns (11th September to 18th October 2012 and 18th January to 17th February 2013). The 24h average PM10 concentration at NFR and FFR were found to be 86.69±18.56μg/m3; 73.16±16.21μg/m3 and 89.44±18.69μg/m3; 81.91±16.42μg/m3, respectively during first and second campaign. In both the campaigns PM10, SO2 and NO2 concentration at NFR was higher than FFR. The chemical characterization of PM10 at NFR and FFR indicated the abundance of major elements such as Na (NFR=30% and FFR=32%), Ca (NFR=12% and FFR=14%) and ions namely NO3− (NFR=71% and FFR=68%) and NH3+ (NFR=15% and FFR=19%). Further, at FFR, SO42− and NO3− were found to be 18% and 35% higher than NFR indicating the conversions of SO2 and NO2 concentration into secondary particles. The measured SO2 and NO2 concentrations were 23 and 21% lower at FFR when compared to NFR confirms the secondary formation.The CALPUFF, EPA regulatory model was set up to understand the dynamics of air pollutants at the industrial complex. The predicted PM10, SO2 and NO2 concentrations at NFR and FFR were found to be 32.31±1.56μg/m3 and 31.35±1.27μg/m3; 0.37±0.21μg/m3 and 0.06±0.04μg/m3; 12.83±6.55μg/m3 and 4.67±2.77μg/m3, respectively. The model showed moderate predictions for PM10 (R2=0.44–0.52), SO2 (R2=0.41–0.51) and NO2 (R2=0.45–0.61) concentrations.

Chemical characteristics of PM2.5–0.3 and PM0.3 and consequence of a dust storm episode at an urban site in Lebanon

Located on the eastern side of the Mediterranean Basin at the intersection of air masses circulating between three continents, the agglomeration of Beirut, capital of Lebanon is an important investigating area for air pollution and more studies are needed to elucidate the composition of the smallest particles classified as carcinogenic to humans. PM2.5–0.3 and PM0.3 samples were collected during the spring-summer period in an urban background site of Beirut, after a dust storm episode occurred, and their chemical composition was determined. Our findings showed that components formed by gas to particle conversion (SO42− and NH4+) and related to combustion processes are mainly found in the PM0.3 fraction. Typical crustal (Ca2+, Fe, Ti, Mg2+), sea-salt (Na+, Cl−, Mg2+, Sr) species, and NO3− are mainly associated with the PM2.5–0.3 fraction. We have also evidenced that the dust episode which occurred in Lebanon in May 2011 originated from the Iraqian and Syrian deserts, which are the least studied, and had a direct influence on the composition of PM2.5–0.3 during the beginning of the first sampling period, and then an indirect and persistent influence by the re-suspension of deposited dust particles. Moreover, PAHs concentrations were much higher in PM0.3 than in PM2.5–0.3 and their composition appeared influenced by diesel (buses, trucks and generator sets) and gasoline (private cars) emissions.

Source Apportionment of PM2.5 in Delhi, India Using PMF Model.

Chemical characterization of PM2.5 [organic carbon, elemental carbon, water soluble inorganic ionic components, and major and trace elements] was carried out for a source apportionment study of PM2.5 at an urban site of Delhi, India from January, 2013, to December, 2014. The annual average mass concentration of PM2.5 was 122±94.1µgm(-3). Strong seasonal variation was observed in PM2.5 mass concentration and its chemical composition with maxima during winter and minima during monsoon. A receptor model, positive matrix factorization (PMF) was applied for source apportionment of PM2.5 mass concentration. The PMF model resolved the major sources of PM2.5 as secondary aerosols (21.3%), followed by soil dust (20.5%), vehicle emissions (19.7%), biomass burning (14.3%), fossil fuel combustion (13.7%), industrial emissions (6.2%) and sea salt (4.3%).

Chemical characterization of atmospheric particulate matter and their source apportionment at an emerging industrial coastal city, Visakhapatnam, India

In the present study, particulate matter (PM10) was collected from two different locations viz. Jogannapalem and Parawada sites of Visakhapatnam. During study period, PM10 concentrations were found in the range from 34.8 to 109.7 μg/m3 and from 32.3 to 137.3 μg/m3 at Jogannapalem and Parawada sites respectively. Chemical characterization of PM10 was carried out to estimate the concentration levels of various particle bound chemical species (Al, V, Cr, Mn, Fe, Ni, Cu, Zn, As, Pb, Cd, Cl−, F-, NO3-, SO42−, Na+, K+, Mg2+ and Ca2+). Among different species, Al was observed to have highest average concentration (4.1 μg/m3 at Jogannapalem and 3.8 μg/m3 at Parawada) at both the sampling sites followed by K at Jogannapalem and Ca at Parawada. PM10 concentration as well as trace metals concentration (except Mn and Fe) was observed to have higher concentrations at Parawada site as compared to Jogannapalem site, indicating higher pollution at Parawada.Source apportionment study carried out using PMF (USEPA PMF5.0) receptor model identified six major sources at Jogannapalem and seven predominant sources at Parawada, which are contributing to collected PM. The two study locations share five common sources viz. crustal, sea salt spray, coal combustion, fuel oil combustion and metal industry. The other sources include biomass burning at Jogannapalem; road traffic and secondary aerosols at Parawada. At Jogannapalem, biomass burning (35%) is the predominant source, whereas coal combustion (22.6%) is dominating at Parawada. PMF factor profiles were observed to have similar elemental profiles obtained at different industrial locations of Visakhapatnam.

Source apportionment of PM2.5 for supporting control strategies in the Monterrey Metropolitan Area, Mexico

ABSTRACTThe Monterrey Metropolitan Area (MMA) in Northeast Mexico has shown high PM2.5 concentrations since 2003. The data shows that the annual average concentration exceeds from 2 to 3 times the Mexican PM2.5 annual air quality standard of 12 µg/m3. In a previous work we studied the chemical characterization of PM2.5 in two sites of the MMA during the winter season. Among the most important components we found ammonium sulfate and nitrate, elemental and organic carbon, and crustal matter. In this work we present the results of a second chemical characterization study performed during the summer time and the application of the chemical mass balance (CMB) model to determine the source apportionment of air pollutants in the region. The chemical analysis results show that the chemical composition of PM2.5 is similar in both sites and periods of the year. The results of the chemical analysis and the CMB model show that industrial, traffic, and combustion activities in the area are the major sources of primary PM2.5 and precursor gases of secondary inorganic and organic aerosol (SO2, NOx, NH3, and volatile organic compounds [VOCs]). We also found that black carbon and organic carbon are important components of PM2.5 in the MMA. These results are consistent with the MMA emission inventory that reports as major sources of particles and SO2 a refinery and fuel combustion, as well as nitrogen oxides and ammonium from transportation and industrial activities in the MMA and ammonium form agricultural activities in the state. The results of this work are important to identify and support effective actions to reduce direct emissions of PM2.5 and its precursor gases to improve air quality in the MMA. Implications: The Monterrey Metropolitan Area (MMA) has been classified as the most air-polluted area in Mexico by the World Health Organization (WHO). Effective actions need to be taken to control primary sources of PM2.5 and its precursors, reducing health risks on the population exposed and their associated costs. The results of this study identify the main sources and their estimated contribution to PM2.5 mass concentration, providing valuable information to the local environmental authorities to take decisions on PM2.5 control strategies in the MMA.

Chemical characteristics of PM2.5 during haze episodes in spring 2013 in Beijing

A continuous daily PM2.5 sampling campaign from 10 April till 8 June 2013, including three haze episodes, was conducted in Beijing. Chemical species, including EC, OC, water-soluble ions and inorganic elements, were analysed by a thermal/optical carbon analyser, IC and ICP-MS, respectively. A comparison of air quality during such haze episodes in relation to clear air situations, as well as the differences between the haze episodes was emphasised. The results showed that the most important fractions of PM2.5 during haze were SO42−, NO3− and NH4+ (namely, SNA) which together accounted for 54–61% of the total PM2.5 mass. Estimated secondary organic carbon (SOC) was also found to be increased during haze, but the relative increase compared to clear days was much lower than for SNA, leading to a decrease in relative contribution of SOC to PM2.5 in the observed haze events. Cluster analyses from back trajectories showed four air mass clusters during spring 2013 and air flow, which was from the south-easterly directions, might favour the accumulation of PM2.5, especially SNA and anthropogenic elements. All these results proved that the anthropogenic air pollution in the Southeast of Beijing was responsible for the formation of hazes in Beijing during spring 2013.

Inter-annual variability of wintertime PM2.5 chemical composition in Xi'an, China: Evidences of changing source emissions

Chemical characteristics of PM2.5 in Xi'an in wintertime of 2006, 2008, and 2010 were investigated. Markers of OC2, EC1, and NO3−/SO42− ratio were calculated to investigate the changes in PM2.5 emission sources over the 5-year period. Positive matrix factorization (PMF) model was used to identify and quantify the main sources of PM2.5 and their contributions. The results showed that coal combustion, motor vehicular emissions, fugitive dust, and secondary inorganic aerosol accounted for more than 80% of PM2.5 mass. The importance of these major sources to the PM2.5 mass varied yearly: coal combustion was the largest contributor (31.2%±5.2%), followed by secondary inorganic aerosol (20.9%±5.2%) and motor vehicular emissions (19.3%±4.8%) in 2006; the order was still coal combustion emissions (27.6%±3.4%), secondary inorganic aerosol (23.2%±6.9%), and motor vehicular emissions (20.9%±4.6%) in 2008; while coal combustion emission further decreased (24.1%±3.1%) with fugitive dust (19.4%±5.5%) increasing in 2010. The changes in PM2.5 chemical compositions and source contributions can be attributed to the social and economic developments in Xi'an, China, including energy structure adjustment, energy consumption, the expansion of civil vehicles, and the increase of urban construction activities.

Chemical Characterization of PM1 at a Regional Background Site in the Western Mediterranean

From February 2011 to September 2012, PM_1 samples were collected at the regional background station of Mt. Aitana, located near the eastern coast of the Iberian Peninsula at 1558 m a.s.l. Samples were subsequently analyzed to determine the major chemical composition (elemental and organic carbon, secondary inorganic ions and oxalate). The seasonal patterns of the concentrations of PM_1 and its main components and the influence of long-range transport of dust from the Sahara desert were studied in this work. PM_1 was mainly composed of organic matter and ammonium sulfate, while EC and nitrate were minor components. Concentrations ranged from 3.4 μg m^(-3) in winter to 5.8 μg m^(-3) during summer. This seasonal cycle is typical of high mountain sites, which are generally above the planetary boundary layer during winter time. All the analyzed components exhibited the same seasonal pattern except nitrate, which showed minimum values in summer. This is most likely the result of the decomposition of NH_4NO_3 favored by the higher summer temperatures. Due to the close proximity to the African continent, PM_1 levels significantly increased during Saharan dust intrusions. The concentrations of sulfate were 35% higher during dust events since the formation of secondary ammonium sulfate is favored by heterogeneous reactions on the surface of mineral particles.

Annual variations of carbonaceous PM&amp;lt;sub&amp;gt;2.5&amp;lt;/sub&amp;gt; in Malaysia: influence by Indonesian peatland fires

Abstract. In this study, we quantified carbonaceous PM2.5 in Malaysia through annual observations of PM2.5, focusing on organic compounds derived from biomass burning. We determined organic carbon (OC), elemental carbon and concentrations of solvent-extractable organic compounds (biomarkers derived from biomass burning sources and n-alkanes). We observed seasonal variations in the concentrations of pyrolyzed OC (OP), levoglucosan (LG), mannosan (MN), galactosan, syringaldehyde, vanillic acid (VA) and cholesterol. The average concentrations of OP, LG, MN, galactosan, VA and cholesterol were higher during the southwestern monsoon season (June–September) than during the northeastern monsoon season (December–March), and these differences were statistically significant. Conversely, the syringaldehyde concentration during the southwestern monsoon season was lower. The PM2.5 OP / OC4 mass ratio allowed distinguishing the seven samples, which have been affected by the Indonesian peatland fires (IPFs). In addition, we observed significant differences in the concentrations between the Indonesian peatland fire (IPF) and other samples of many chemical species. Thus, the chemical characteristics of PM2.5 in Malaysia appeared to be significantly influenced by IPFs during the southwestern monsoon season. Furthermore, we evaluated two indicators, the vanillic acid / syringic acid (VA / SA) and LG / MN mass ratios, which have been suggested as indicators of IPFs. The LG / MN mass ratio ranged from 14 to 22 in the IPF samples and from 11 to 31 in the other samples. Thus, the respective variation ranges partially overlapped. Consequently, this ratio did not satisfactorily reflect the effects of IPFs in Malaysia. In contrast, the VA / SA mass ratio may serve as a good indicator, since it significantly differed between the IPF and other samples. However, the OP / OC4 mass ratio provided more remarkable differences than the VA / SA mass ratio, offering an even better indicator. Finally, we extracted biomass burning emissions' sources such as IPF, softwood/hardwood burning and meat cooking through varimax-rotated principal component analysis.

Chemical characterization of PM2.5 emitted from on-road heavy-duty diesel trucks in China

Heavy-duty diesel trucks (HDDTs) are gaining more attention because of their contribution to NOX and PM2.5 emissions. To evaluate their contribution to ambient fine particulate matter (PM2.5), not only their emission factors, but also their source profile is required. We conducted on-road emissions tests to characterize the PM2.5 emission, documenting per second mass emission rates from in-use HDDTs in China, using portable emissions measurement systems. The average PM2.5 emission factors for pre-EURO and EURO 1 HDDTs were 1.104 g/km and 0.822 g/km, equivalent to 6.106 g/kg and 3.132 g/kg based on fuel consumption. Element carbon (EC) and organic carbon (OC) were the major components: EC accounted for 45–65% of PM2.5 for pre-EURO HDDTs and 36–69% for EURO 1 HDDTs, while the OC fraction for pre-EURO and EURO 1 HDDTs ranged from 20 to 31% and 19–31%, respectively. Thus, the average EC emission factors for pre-EURO and EURO 1 HDDTs were 0.667 g/km and 0.502 g/km, showing that implementation of tighter emission standards resulted in a 25% EC output reduction from pre-EURO to EURO 1 vehicles. Sulfate, comprising about 1% of PM2.5 mass, is still an abundant species in PM2.5 from HDDTs because of the high sulfur content in diesel fuel in China. Using these data, we updated national PM2.5 emission profiles for pre-EURO and EURO 1 HDDTs.

Concentration and chemical composition of PM2.5 for a one-year period at Thessaloniki, Greece: A comparison between city and port area

The chemical characterization of PM2.5 fraction was studied during a one-year sampling campaign conducted at an urban area (city center) of Thessaloniki, Greece. PM2.5 samples were analyzed for polycyclic aromatic hydrocarbons, minerals and trace elements, water soluble ions, organic and elemental carbon. The average PM2.5 concentration (37.7 μg/m3) was significantly higher than the EU legislated annual limit of 25 μg/m3 underlining the temporal problems of air quality in the city. PM mass and chemical composition data collected at the city center were compared to the corresponding data which were simultaneously collected at a site near the port. The atmosphere in the port area has been found to be more aggravated compared to the city center area. Statistical analysis and diagnostic ratios of the collected chemical data at both sites were used to identify the main sources contributing to the pollutant levels: traffic, biomass burning for domestic heating, shipping and port activities and dust resuspension. In general, chemical analysis highlighted that PM2.5 mass was mainly composed by secondary inorganic aerosols and particulate organic matter, reflecting the simultaneous contribution of both regional and local emission sources.

Seasonal variations and chemical characteristics of PM2.5 in Wuhan, central China

PM2.5 samples were collected at an urban site (WD) and a suburban site (TH) in Wuhan from August 2012 to July 2013. The mass concentrations of water-soluble inorganic ions, carbonaceous species and elements of PM2.5 were measured. The annual mean concentrations of PM2.5 were 106.5μg/m3 and 114.9μg/m3 at WD and TH, respectively. The chemical compositions of PM2.5 at WD were similar to those at TH and the fractions of the major components of PM2.5 in Wuhan were in the following order of trace elements<chloride<EC (elemental carbon)<ammonium<nitrate<soil dust<sulfate<OM (organic matter). As the secondary ionic aerosols (SIA) and dominant ions, SO42−, NO3− and NH4+ all exhibited strong seasonal distributions, consistently with the lowest values in summer and the highest in winter. OM was the most abundant component in PM2.5, the lowest concentrations of which were observed in summer at both sites, while the highest concentrations of OC (organic carbon) appeared in winter at WD and autumn at TH, respectively. The highest OC concentration observed in autumn was tightly related to the biomass burning near the suburban site. The crustal elements (Mg, K, Ca and Fe) dominated the 20 detected elements in PM2.5, with the highest concentrations in spring in Wuhan, which might be due to frequent sandstorm from north carrying abundant soil dusts in spring in China. Ten trace elements (Cu, Ga, Ag, Tl, Ca, As, Zn, Pb, Se and Cd) were enriched in PM2.5 and the higher EF for Ag, Pb, Se and Cd in PM2.5 indicated that the air pollution from vehicle exhaust emission and coal burning in Wuhan was serious and noteworthy.