Chemical Composition Of PM2 Research Articles

Aerosol optical properties under different pollution levels in the Pearl River Delta (PRD) region of China

To clarify the aerosol hygroscopic growth and optical properties of the Pearl River Delta (PRD) region, integrated observations were conducted in Heshan City of Guangdong Province from October 19 to November 17, 2014. The concentrations and chemical compositions of PM2.5, aerosol optical properties and meteorological parameters were measured. The mean value of PM2.5 increased from less than 35 (excellent) to 35-75 μg/m3 (good) and then to greater than 75 μg/m3 (pollution), corresponding to mean PM2.5 values of 24.9, 51.2, and 93.3 μg/m3, respectively. The aerosol scattering hygroscopic growth factor (f(RH = 80%)) values were 2.0, 2.12, and 2.18 for the excellent, good, and pollution levels, respectively. The atmospheric extinction coefficient (σext) and the absorption coefficient of aerosols (σap) increased, and the single scattering albedo (SSA) decreased from the excellent to the pollution levels. For different air mass sources, under excellent and good levels, the land air mass from northern Heshan had lower f(RH) and σsp values. In addition, the mixed aerosol from the sea and coastal cities had lower f(RH) and showed that the local sources of coastal cities have higher scattering characteristics in pollution periods.

The pollution characteristics of PM10 and PM2.5 during summer and winter in Beijing, Suning and Islamabad

To understand the atmospheric particulate pollution characteristics of cities in different sizes and regions, PM10 and PM2.5 were simultaneously collected in three cities: Beijing, China, Islamabad, Pakistan and Suning, China, in summer (2016) and winter (2017), respectively. The associated species including carbonaceous, metal elements and water soluble ions were analyzed. Both PM10 and PM2.5 concentrations in winter are higher than those in summer in three cities. In Beijing, OM, NH4NO3 and (NH4)2SO4 are the main components, the PM2.5/PM10 ratio is the highest among three cities, and the NO3−/SO42− ratio is lower than that in Islamabad in winter, suggesting that coal-fired process contributed more in Beijing. In Islamabad, the main components of PM10 and PM2.5 are crust and OM. The average concentrations of both Ca and Na in PM10 are higher than those in Beijing and Suning, indicating that the soil dust may be one of main air pollution sources in Islamabad. The concentrations of OC in both PM10 and PM2.5 in Islamabad are in relatively high level in summer, which indicates that more secondary organic aerosols are formed in summer in Islamabad. The highest PM10 and PM2.5 concentrations occur in Suning and the chemical composition of PM2.5 in Suning is similar to that in Beijing whether it is summer or winter, and the proportion of EC in Suning is higher than that in the other two cities in both PM10 and PM2.5, which are attributed to atmospheric pollutants transport from the surrounding cities and the diesel vehicle emission.

Spatial and Temporal Variations of PM2.5 in North Carolina

Studies have indicated that the adverse effects on human health and the decrease in visibility caused by fine particulate matter (PM2.5) exhibit spatial heterogeneity. Moreover, the environmental effects produced by different chemical compositions of PM2.5 vary on a regional scale. Therefore, understanding the spatiotemporal variations and chemical compositions of PM2.5 is necessary for assessing the regional impacts. Secondary inorganic PM2.5 (iPM2.5) is formed through chemical reactions between the base gas NH3 and acidic gas pollutants (e.g., NO2 or SO2). The major components of iPM2.5 include NH4+, SO42–, and NO3–. To fully comprehend the regional impacts of PM2.5, this research quantifies the spatiotemporal variations of iPM2.5 with the aim of evaluating the contributions from iPM2.5 to PM2.5 in North Carolina (NC). The concentrations (at 34 sites) and chemical components (at 7 sites) of PM2.5 from 2005 to 2014 were extracted from the EPA’s AirData, with the highest concentrations measured in the urban areas of central NC. Notably, PM2.5 concentrations have been significantly reduced over the past 10 years, with a concurrent decreasing trend in iPM2.5. Seasonal variation analysis indicates that PM2.5 concentrations were higher in summer and lower in winter; however, significant variation occurred only between 2005 and 2011. Although iPM2.5 formed the largest mass fraction of PM2.5 for 2005–2011, organic carbon matter (OCM) contributed the dominant share for 2012–2014. Significant seasonal variations in the iPM2.5 mass fractions were also observed, with NO3– and SO42– exhibiting inverse variations. This study links the ambient PM2.5 to various sources by revealing the spatiotemporal variations of PM2.5 and their associated chemical compositions in NC, thereby enabling the development of effective control and mitigation strategies.

Speciated PM Composition and Gas and Particle Emission Factors for Diesel Construction Machinery in China

ABSTRACT On-board emission measurements were performed on nine diesel construction machines operated under real-world conditions in China. The emission factors (EFs) for NOx, CO, the total hydrocarbons, PM, and the particle number concentration were determined under actual operating conditions, i.e., during idling, moving, and working. To investigate the chemical composition of PM from diesel machinery, organic carbon (OC), containing particulate organic matter (POM); elemental carbon (EC); water-soluble ions (WSIs); and elements were also analyzed herein. OC was the most abundant component (contributing 39.3 ± 11% of the mass), followed by EC (37.7 ± 13%). POM species, including n-alkanes, hopanes, polycyclic aromatic hydrocarbons (PAHs), and n-fatty acids, contributed approximately 2.4–6.4% of the total PM mass. Compounds with 3 or 4 aromatic rings, including pyrene, phenanthrene, and fluoranthene, dominated the particulate PAHs, accounting for 62% of the total mass. These results are consistent with those of previous studies and can help to minimize uncertainties in emission inventories and source apportionment for non-road machinery.

Optical properties of Sydney aerosols

Aerosol chemistry for PM2.5 and PM10 (particulate matter less than 2.5- and 10-μm aerodynamic diameter) samples collected in the Sydney region between November 2002 and December 2003 had been used to estimate size-resolved refractive index for Sydney. Seasonal PM10–2.5 chemistry was obtained by subtracting seasonal PM2.5 from seasonal PM10 chemical composition. The chemical compounds present were determined from the elemental composition using two methods: the SCAPE 2 chemical thermodynamic model and aerosol types based on marker elements. Refractive index was then calculated using a mass fraction approach. Both methods agreed within the error bars indicating that useful optical properties can be derived from elemental chemistry. For the fine mode (PM2.5), the real component of the refractive index was 1.46 ± 0.07 with no seasonal variation, but there were sea-sonal variations in imaginary component, 0.05 ± 0.02 in summer and 0.23 ± 0.05 in spring. The coarse mode (PM10–2.5) real refractive index was constant throughout the year at 1.47 ± 0.09, whereas the im-aginary refractive index was 0.01 ± 0.04 in summer and 0.04 ± 0.06 in spring. Representative refractive indices were then used to calculate aerosol scattering properties for three different size distributions to illustrate how this information could be used.

A Study on the Characteristics of PM1.0 Chemical Components Using a Real-time Aerosol Mass Spectrometer

This study aims to identify the characteristics of oxidation and chemical composition of PM in winter season, 2017 at Incheon area. The mean concentration of air pollutants were 46 ± 22 μg/m3-PM10, 29 ± 18 μg/m3/-PM2.5, 5 ± 3 ppb-SO2, 0.56 ± 0.24 ppm-CO, 21 ± 13 ppb-O3 and 28 ± 17 ppb-NO2, respectively. The dominant ion of the PM1.0 chemical component were organic with 3.2 μg/m3 and nitrate with 1.9 μg/m3. The day and night variation of the PM1.0 chemical components was higher in nighttime than those of daytime. The averaged nitrate oxidation rate (SOR) was 0.06 and sulfate oxidation rate was 0.11 during the field campaign. In the high mass loading period, nitrate oxidation rate (NOR) was up to 0.6 and also the nitrate in PM1.0 was increased. The averaged ratio of NOx/SO2 was 8.7 and nitrate/sulfate was 3.1, respectively. In this results, the nitrate component in PM1.0 was influenced by NOx from the stationary source as power plant and the mobile source around the measurement site.

Chemical Characteristics of Fine Particulate Matter in Poland in Relation with Data from Selected Rural and Urban Background Stations in Europe

Air pollution by particulate matter (PM) is recognized as a one of the most important environmental issue. A particular attention is being paid to fine PM fraction (PM2.5, PM1.0) due to its detrimental impact on human health and long-term persistence in the air. Presented work is an in-depth bibliometric study on the concentrations and chemical composition of PM2.5 among 27 rural and 38 urban/urban background stations dispersed across the Europe. Obtained results indicate that the chemical composition of PM2.5, in terms of mass concentrations and percentage contribution of main chemical constituents, is relatively different in various parts of Europe. Urban and urban background stations are typically characterized by higher share of total carbon (TC) in PM2.5, compared to rural background sites, mostly pronounced during the heating periods. The share of the secondary inorganic aerosol (SIA) is typically higher at rural background stations, especially in North-Western Europe. In general, the relative contribution of SIA in PM2.5 mass, both at rural and urban background stations, showed more or less pronounced seasonal variation, opposite to Polish measurement sites. Moreover, Poland stands out from the majority of the European stations by strong dominance of total carbon over secondary inorganic aerosol.

Profile of inhalable bacteria in PM2.5 at Mt. Tai, China: Abundance, community, and influence of air mass trajectories

Bacteria are ubiquitous in the near-surface atmosphere where they constitute an important component of aerosols with the potential to affect climate change, ecosystems, atmospheric process and human health. Limitation in tracking bacterial diversity accurately has thus far prevented the knowledge of airborne bacteria and their pathogenic properties. We performed a comprehensive assessment of bacterial abundance and diverse community in PM2.5 collected at Mt. Tai, via high-throughput sequencing and real-time PCR. The samples exhibited a high microbial biodiversity and complex chemical composition. The dominating populations were gram-negative bacteria including Burkholderia, Delftia, Bradyrhizobium, and Methylobacterium. The PM mass concentration, chemical composition, bacterial concentration and community structure varied under the influence of different air-mass trajectories. The highest mass concentration of PM2.5 (61 μg m−3) and major chemical components were recorded during periods when marine southeasterly air masses were dominant. The local terrestrial air masses from Shandong peninsula and its adjacent areas harbored highest bacterial concentration loading (602 cells m−3) and more potential pathogens at the site. In contrast, samples influenced by the long-distance air flow from Siberia and Outer Mongolia were found to have a highest richness and diversity as an average, which was also marked by the increase of dust-associated bacteria (Brevibacillus and Staphylococcus). The primary research may serve as an important reference for the environmental microbiologist, health workers, and city planners.

Biological and chemical compositions of atmospheric particulate matter during hazardous haze days in Beijing

Particulate matter (PM), a major air pollutant in Beijing in recent years, poses a formidable public health threat. Even through many studies have documented the chemical and biological characteristics of PM, less is known about these characteristics on hazardous haze days (Air Quality Index, AQI 301–500) and the difference with sunny or unhealthy haze day (AQI 151–200) characteristics. Herein, studies were performed during a red alert air pollution event (continuous hazardous haze days) and the first few days following the event (sunny days first and then unhealthy haze days) in Beijing from December 19 to 25, 2016. A laser particle counter and an ANDERSEM-6 sampler were used to study the concentration and size distributions dynamics of the PM and the culturable airborne bacteria and fungi, respectively. PM2.5 was sampled by a high-volume air sampler and the chemical compositions, bacterial and fungal community structures, and endotoxin levels were analyzed. The results showed that the PM concentrations on the hazardous haze days and unhealthy haze days were 10.7 and 8.0 times higher, respectively, than those on the sunny days. The chemical composition of PM2.5 was highly correlated with the AQI. The concentration and percentage of water-soluble inorganic ions (WSII), which dominated the PM2.5 constituents, as well as the levels of endotoxin were higher on hazardous haze days than on unhealthy haze days and sunny days. Interestingly, the abundances of bacteria and fungi demonstrated the following order: unhealthy haze days> sunny days> hazardous haze days. Most culturable bacteria and fungi were distributed in particles with aerodynamic diameters of 2.1–4.7 μm. Redundancy analysis found total organic carbon explained 30.0% and 27.1% of total variations in bacterial composition and fungal composition at the genera level, respectively. Our results facilitate a better understanding of the biological and chemical composition dynamics of PM in Beijing.

Air quality in the middle and lower reaches of the Yangtze River channel: a cruise campaign

Abstract. The Yangtze River is the longest river in China; nearly one-third of the national population lives along the river. Air quality over the Yangtze River is important as it may have significant influences on the aquatic ecosystem, the health of everyone living along the Yangtze River, and regional climate change. Chemical compositions of ambient aerosol were determined during a comprehensive cruise campaign carried out along the mid–lower reaches of the Yangtze River (MLYR) in winter of 2015. The total average concentration of PM2.5 was 119.29±33.67 µg m−3, and the dominant ionic composition in PM2.5 was SO42- with an average concentration of 15.21±6.69 µg m−3, followed by NO3- (13.76±4.99 µg m−3), NH4+ (9.38±4.35 µg m−3), and Ca2+ (2.23±1.24 µg m−3) in this cruise. Based on the filter samples, the concentration and chemical composition of PM2.5 were remarkably varied or fluctuated from coastal areas to inland over the MLYR region. Crustal elements (Ca, Mg, Al, and K) from floating dust showed peak concentrations in the Yangtze River Delta (YRD) region, while secondary inorganic species (SO42-, NO3-, and NH4+) and some of the most enriched elements (Pb, As, Se, and Cd) presented high levels in central China (Wuhan region). The significant correlation between Se and SO42- suggested that coal combustion may play an important role in secondary inorganic aerosol formation. The relatively high enrichment factors (EFs) of Ca (EFs >100) suggested the crustal elements may derive from anthropogenic sources. Furthermore, the concentration of levoglucosan in PM2.5 and the CO column level from satellite observation were greatly enhanced in the rural areas (Anhui and Jiangxi), indicating that biomass burning may make a remarkable contribution to rural areas. The concentrations of typical tracer for heavy oil (V and Ni) significantly increased in the Shanghai port, which was mainly ascribed to ship emissions, based on the air mass source analysis and the relatively high ratio of V ∕ Ni as well. The results shown herein portray a good picture of air pollution along the Yangtze River.

In vitro and in vivo toxic effects and inflammatory responses induced by carboxylated black carbon-lead complex exposure

Black carbon (BC) is a key component of atmospheric fine particulate matter (PM2.5) and it tends to adsorb various pollutants (e.g., heavy metals and organics) during atmospheric transport. This adsorption leads to the complexity and uncertainty of the source and chemical composition of PM2.5, making the toxicologic effects and health risks induced by PM2.5 difficult to determine. Here, we used carboxylated black carbon (c-BC) and c-BC-lead complexes (c-BC-Pb) to investigate the in vitro and in vivo toxic effects and inflammatory responses. The physicochemical properties of c-BC and c-BC-Pb complexes were characterized by the transmission electron microscope (TEM), X-ray photoelectron spectroscopy (XPS), dynamic light scattering (DLS), and in ductively coupled plasma–atomic emission spectra (ICP−AES). Cytotoxicity in vitro showed that the exposure of human bronchial epithelial cells (BEAS-2B) to low-dose c-BC-Pb particles significantly induced greater toxicity than that of c-BC, suggesting that lead (Pb) might play an important role in induced cytotoxicity after combined exposure to c-BC-Pb particles. The findings were further confirmed by the results in vivo, which indicated that c-BC-Pb particles significantly induced inflammation and lung injury. Based on the results of this experiment, the differences in toxicity can be attributed to the synergistic effect of Pb on the BC particles, which play a synergistic role in vitro and in vivo in the development of toxicity. The c-BC-Pb particles model used in this study may be helpful for the evaluation of cytotoxicity induced by different sources of BC particles or BC-heavy metal complexes and provide a new approach for understanding PM2.5-induced toxicity and health risks.

PM2.5 Pollution Characterization and Cause Analysis of a Winter Heavy Pollution Event, Liaocheng City

Heavy pollution events frequently occur during fall and winter seasons in northern areas. In order to understand the characteristics and chemical composition of PM2.5 during heavy pollution in winter in Liaocheng City, ambient PM2.5 samples were collected between January 7-11,2016. Mass concentration, water-soluble ions, carbonaceous species, and elements were analyzed, as well as the causes of pollution. Results showed that PM2.5 mass concentration was 238.3 μg·m-3 with the trend clearly that of an inverted V; this concentration represents exceedance of the National Ambient Air Quality Standard (GB 3095-2012) by more than 2.2 times. NO3-, SO42-, and NH4+(SNA)were the main water-soluble ions. As pollution increased or decreased, NH4+, SO42-, NO3-, and Cl- exhibited the same trend, which contrasted with that of Ca2+. During the peak of pollution, NH4+, NO3-, and SO42- concentrations were 48.96, 68.45, and 80.55 μg·m-3, with these representing levels 6.29, 7.31, and 7.84 times those of the initial stage, respectively. During the pollution event, OC and EC concentration variation ranges were 20.8-60.2 μg·m-3, and 3.0-7.5 μg·m-3, respectively. The concentration of OC was significantly higher than that of EC and the variation amplitude was significantly larger. During the event, the mass concentrations of 27 inorganic elements on each day were 10.2, 22.4, 16.0, 19.6, and 8.2 μg·m-3, respectively. Enrichment factors (EF) of all elements were less than 10, indicating lack of enrichment and showing that sources were mainly natural. PM2.5 mass concentration reconstruction results showed that organic matter (OM), SO42-, and NO3- were major components, followed by NH4+, crustal material, and other ions. EC and trace element content was relatively low. As PM2.5 pollution worsened, secondary inorganic salt (NH4+, SO42-, NO3-) concentrations and proportions increased, OM concentration increased but its proportion decreased, while crustal material concentration and proportion both decreased, showing that secondary inorganic conversion was the main cause of this pollution event, mainly driven by coal and motor vehicle emissions.

Carbonaceous components and major ions in PM10 from the Amazonian Basin

Air pollution mainly resulting from deforestation and agricultural activities has become one of the major concerns in the Amazonian Basin. A detailed analysis of the PM10 chemical composition is critical for devising pollution control measures and improving climate models. In this study, daily 24-h filter samples were collected and analyzed in different sites of the Amazon Basin between 2008 and 2016 (over 200 samples). The six sampling sites were classified into two groups, one in South Amazonia, a region with strong influence of land occupation, and another in a remote forest region to the North. The high mean concentrations of PM10 and the occurrences of extreme events at the Southern site denote air pollution episodes. High correlations between the temporal trends of PM10 and primary species linked to soil re-suspension and biomass burning highlight the contribution of these sources of air pollution in the region. Significant differences between PM10 in the South and North regions were observed, for which levels of 72.6 ± 66.5 μg m−3 and 8.9 ± 4.2 μg m−3, respectively. The average concentrations of organic carbon (OC) and elemental carbon (EC) in the aerosol were 5.81 ± 4.18 μg m−3, 2.43 ± 1.65 μg m−3 and 5.17 ± 5.54 μg m−3, 0.51 ± 0.41 μg m−3, respectively, for the Southern and Northern Amazonia sampling sites. The aerosol was largely composed of inorganic species in Southern Amazonia, whose carbonaceous matter accounted for 16% of the gravimetrically measured PM10. However, in the forest region, the contribution of carbonaceous species, mainly OC, accounted for >90% and remained more constant throughout the seasons. Na+ was the dominant water soluble ion in samples from the Southern region, followed by SO4−2, NO3−, Ca2+ and K+. High levels of carbonate (CC) were also observed for these samples. For the Northern region, SO4−2 was the dominant soluble ion, followed by K+ and NH4+. Some of these species exhibited a clear seasonal trend during the study period. This study provides a better understanding of the current state of air pollution in diversified Amazon basin sites.

In vitro lung toxicity of indoor PM10 from a stove fueled with different biomasses

Biomass combustion significantly contributes to indoor and outdoor air pollution and to the adverse health effects observed in the exposed populations. Besides, the contribution to toxicity of the particles derived from combustion of different biomass sources (pellet, wood, charcoal), as well as their biological mode of action, are still poorly understood. In the present study, we investigate the toxicological properties of PM10 particles emitted indoor from a stove fueled with different biomasses.PM10 was sampled by gravimetric methods and particles were chemically analyzed for Polycyclic Aromatic Hydrocarbons (PAHs) and elemental content. Human lung A549 cells were exposed for 24 h to 1–10 μg/cm2 PM and different biological endpoints were evaluated to comparatively estimate the cytotoxic, genotoxic and pro-inflammatory effects of the different PMs.Pellet PM decreased cell viability, inducing necrosis, while charcoal and wood ones mainly induced apoptosis. Oxidative stress-related response and cytochrome P450 enzymes activation were observed after exposure to all the biomasses tested. Furthermore, after pellet exposure, DNA lesions and cell cycle arrest were also observed. The severe genotoxic and pro-necrotic effects observed after pellet exposure were likely the consequence of the high metal content. By administering the chelating agent TPEN, the genotoxic effects were indeed rescued. The higher content in PAHs measured in wood and charcoal PMs was likely the reason of the enhanced expression of metabolizing and oxidative stress-related enzymes, like CYP1B1 and HO-1, and the consequent increase in apoptotic cell death.These data suggest that combustion particles from different biomass sources may impact on lung cells according to different pathways, finally producing different toxicities. This is strictly related to the PM chemical composition, which reflects the quality of the combustion and the fuel in particular. Further studies are needed to clarify the role of particle dimension and the molecular mechanisms behind the harmful effects observed.

Seasonal variations of PM1-bound water concentration in urban areas in Poland

Ambient concentrations and seasonal variability of water bound to ambient fine particulate matter (PM 1 -bound water) were investigated at two urban sites, the cities Zabrze and Warsaw (southern and central Poland, respectively), in summer and winter. The types and numbers of PM 1 sources differ extremely between the two cities in one season and between the two seasons in one city, therefore the chemical compositions of PM 1 differ as well. Water and other main PM 1 components (ions of water soluble compounds, organic and elemental carbon) were determined in the PM 1 samples and their amounts comparatively analyzed. The large effect of solid fuel (hard coal) burning for residential heating on chemical composition and concentrations of PM 1 makes the concentrations of PM 1 -bound water and their seasonal changes greater in Zabrze than in Warsaw, where PM 1 in winter comes mainly from natural gas burning and from road traffic. • First study on water content of PM in Poland. • Relationships between PM 1 -bound water, EC, OC, Cl − , NO 3 − , PO 4 3− , SO 4 2− , F − , Na + , NH 4 + , K + , Ca 2+ , and Mg 2+ . • Solid fuel combustion causes high ambient concentrations of PM 1 -bound water.

Chemical composition and source identification of PM10 in five North Western European cities

Particulate matter (PM) is a complex, heterogeneous mixture that changes in time and space. It has many different chemical constituents, several of which have been identified as potential contributors to toxicity, and varying physical characteristics. Identifying and quantifying the effects of specific components or source-related combinations on human health, particularly when particles interact with other co-pollutants, therefore represents one of the most challenging areas of environmental health research. Owing to the importance of PM10 chemical composition in understanding particulate pollution sources, 1942 PM10 samples were simultaneously collected at five sites (four urban background sites located in Amsterdam (AD), Antwerp (AP), Leicester (LE) and Lille (LL), and one industrial site at Wijk aan Zee (WZ)) across North-West Europe from April 2013 to May 2014, and chemical species and sources of PM10 were investigated. PM10 samples were chemically analysed for water-soluble ions (NO3−, SO42−, Cl−, NH4+, Na+, K+, Mg2+, and Ca2+), carbonaceous species (OC, and EC), minerals (Al, Ca, Fe, Ti, and K), trace elements (As, Ba, Cd, Cr, Cu, Mn, Mo, Ni, Pb, Sb, V, and Zn), and monosaccharides (levoglucosan, galactosan, and mannosan). Spatial and seasonal variations of the atmospheric concentrations of species were also investigated. In order to reconstruct the particle mass, the determined constituents were classified into seven classes as follows: mineral dust (MD), organic matter (OM), elemental carbon (EC), trace elements (TE), sea salt (SS), secondary inorganic aerosol (SIA), and monosaccharides (MSS). Strong correlations (R2 = 0.88–0.96) were found between chemically determined and gravimetrically measured PM10 masses for all sites. According to chemical mass closure, the major components of PM10 were SIA, followed by OM and MD at the four urban sites, and the major components of PM10 were SIA, followed by MD and SS at an industrially influenced site. SIA dominated the PM10 profiles at all sites, accounting for 36, 35, 32, 36, and 32% at AD, AP, LE, LL, and WZ, respectively. Five PCA factors explained 67, 80, 76, and 74% of the variance of the data at AD, AP, LL and WZ respectively. In addition, four factors are extracted for LE site explaining 71% of the variance. The PCA results showed that secondary aerosols, biomass burning, and traffic emissions were the most important sources across North-West Europe.

Characteristics of PM<sub>2.5</sub> mass concentrations and chemical species in urban and background areas of China: emerging results from the CARE-China network

Abstract. The “Campaign on Atmospheric Aerosol Research” network of China (CARE-China) is a long-term project for the study of the spatio-temporal distributions of physical aerosol characteristics as well as the chemical components and optical properties of aerosols over China. This study presents the first long-term data sets from this project, including 3 years of observations of online PM2.5 mass concentrations (2012–2014) and 1 year of observations of PM2.5 compositions (2012–2013) from the CARE-China network. The average PM2.5 concentration at 20 urban sites is 73.2 µg m−3 (16.8–126.9 µg m−3), which was 3 times higher than the average value from the 12 background sites (11.2–46.5 µg m−3). The PM2.5 concentrations are generally higher in east-central China than in the other parts of the country due to their relatively large particulate matter (PM) emissions and the unfavourable meteorological conditions for pollution dispersion. A distinct seasonal variability in PM2.5 is observed, with highs in the winter and lows during the summer at urban sites. Inconsistent seasonal trends were observed at the background sites. Bimodal and unimodal diurnal variation patterns were identified at both urban and background sites. The chemical compositions of PM2.5 were analysed at six paired urban and background sites located within the most polluted urban agglomerations – North China Plain (NCP), Yangtze River delta (YRD), Pearl River delta (PRD), North-east China region (NECR), South-west China region (SWCR) – and the cleanest region of China – the Tibetan Autonomous Region (TAR). The major PM2.5 constituents across all the urban sites are organic matter (OM, 26.0 %), SO42- (17.7 %), mineral dust (11.8 %), NO3- (9.8 %), NH4+ (6.6 %), elemental carbon (EC) (6.0 %), Cl− (1.2 %) at 45 % RH and unaccounted matter (20.7 %). Similar chemical compositions of PM2.5 were observed at background sites but were associated with higher fractions of OM (33.2 %) and lower fractions of NO3- (8.6 %) and EC (4.1 %). Significant variations of the chemical species were observed among the sites. At the urban sites, the OM ranged from 12.6 µg m−3 (Lhasa) to 23.3 µg m−3 (Shenyang), the SO42- ranged from 0.8 µg m−3 (Lhasa) to 19.7 µg m−3 (Chongqing), the NO3- ranged from 0.5 µg m−3 (Lhasa) to 11.9 µg m−3 (Shanghai) and the EC ranged from 1.4 µg m−3 (Lhasa) to 7.1 µg m−3 (Guangzhou). The PM2.5 chemical species at the background sites exhibited larger spatial heterogeneities than those at urban sites, suggesting different contributions from regional anthropogenic or natural emissions and from long-range transport to background areas. Notable seasonal variations of PM2.5-polluted days were observed, especially for the megacities in east-central China, resulting in frequent heavy pollution episodes occurring during the winter. The evolution of the PM2.5 chemical compositions on polluted days was consistent for the urban and nearby background sites, where the sum of sulfate, nitrate and ammonia typically constituted much higher fractions (31–57 %) of PM2.5 mass, suggesting fine-particle pollution in the most polluted areas of China assumes a regional tendency, and the importance of addressing the emission reduction of secondary aerosol precursors including SO2 and NOx. Furthermore, distinct differences in the evolution of [NO3-]/[SO42-] ratio and OC∕EC ratio on polluted days imply that mobile sources and stationary (coal combustion) sources are likely more important in Guangzhou and Shenyang, respectively, whereas in Beijing it is mobile emission and residential sources. As for Chongqing, the higher oxidation capacity than the other three cities suggested it should pay more attention to the emission reduction of secondary aerosol precursors. This analysis reveals the spatial and seasonal variabilities of the urban and background aerosol concentrations on a national scale and provides insights into their sources, processes and lifetimes.

Metabolic impact induced by total, water soluble and insoluble components of PM2.5 acute exposure in mice

Fine particulate matter (PM2.5) has been listed as an important environmental risk factor for human health. However, the systemic biological effects on metabolic responses induced by PM2.5 and its components were poorly understood. This study was aimed to evaluate the toxicity of different components of PM2.5 at molecular level via metabolomics approach. In the present study, we adopted a 1H NMR-based metabolomics approach to evaluate metabolic profiles in mice after acute exposure to Total-PM2.5, water soluble components of PM2.5 (WS-PM2.5) and water insoluble components of PM2.5 (WIS-PM2.5). First, we characterized the morphological features and chemical composition of PM2.5. Then, the metabolites changes of serum and urine in mice were systematically analyzed using 800 MHz 1H NMR techniques in combination with multivariate statistical analysis. Total-PM2.5 exposure affected metabolites mainly involved in amino acid metabolism, protein biosynthesis, energy metabolism and metabolism of cofactors and vitamins. WS-PM2.5 exposure influenced lipid metabolism and carbohydrate metabolism. WIS-PM2.5 exposure mainly perturbed amino acid metabolism and energy metabolism. The results suggested that acute exposure to the Total-PM2.5, WS-PM2.5 and WIS-PM2.5 in mice exhibited marked systemic metabolic changes. In addition, the insoluble fraction of PM2.5 contributed greatly to the toxicity of PM2.5.

Chemical profiles and metabolite study of raw and processed Polygoni Multiflori Radix in rats by UPLC-LTQ-Orbitrap MSn spectrometry

The raw and processed roots of Plygonum multiflorum Thunb (PM) are used to treat different diseases in clinical practice. In order to clarify the influence of processing, a comparative study of chemical substance analysis was carried out. As the xenobiotics with a high enough exposure in target organs being considered as the potential effective or toxicity components, an in vivo study was also implemented to characterize the constitutes and metabolites, and meanwhile, the factor of compatibility with black bean were also considered. As a result, a total of 148 compounds were detected in PM extracts and more than 40 compounds were only detected in the processed products, which were probably new components produced during the steaming process. In in vivo study, 7 prototype components and 66 metabolites were detected or tentatively identified, 24 of which were reported for the first time. Our results indicated that processing greatly changed the chemical composition of PM and influenced the disposition of the compounds in vivo. To the best of our knowledge, this was the first global comparative study of raw and processed PM. These results expanded our knowledge about the influence of processing of PM and provided the essential data for further efficacy or toxicity studies.

Physical and chemical characteristics of PM2.5 and its toxicity to human bronchial cells BEAS-2B in the winter and summer.

With the increasing occurrence of haze during the summer, the physicochemical characteristics and toxicity differences in PM2.5 in different seasons are of great concern. Hangzhou is located in an area that has a subtropical monsoon climate where the humidity is very high during both the summer and winter. However, there are limited studies on the seasonal differences in PM2.5 in these weather conditions. In this test, PM2.5 samples were collected in the winter and summer, the morphology and chemical composition of PM2.5 were analyzed, the toxicity of PM2.5 to human bronchial cells BEAS-2B was compared, and the correlation between PM2.5 toxicity and the chemical composition was discussed. The results showed that during both the winter and summer, the main compounds in the PM2.5 samples were water-soluble ions, particularly SO42-, NO3-, and NH4+, followed by organic components, while heavy metals were present at lower levels. The higher the mass concentration of PM2.5, the greater its impact on cell viability and ROS levels. However, when the mass concentration of PM2.5 was similar, the water extraction from the summer samples showed a greater impact on BEAS-2B than that from the winter samples. The cytotoxicity of PM2.5 was closely associated with heavy metals and organic pollutants but less related to water-soluble ions.