Mass Concentrations Of PM2 Research Articles

Trace elements in ambient aerosols and size-resolved fog droplets: Trends, enrichment, and risk assessment

Ambient particulate matter (PM) is composed of inorganic and organic components. The contribution of each component is impacted by various factors such as emission sources, atmospheric aging process, and size of the PM or droplets. This study mainly focuses on the effect of the PM and droplet size on trace elemental concentrations, for which various size fractions of ambient PM (PM1, PM2.5) were collected on quartz filters along with fog water (FW) samples during winter. Simultaneous, online measurements of the mass concentrations of PM1 and PM2.5 were also carried out. At the time of the collection, the mass concentration of PM2.5 ranged from 19 to 890 μg/m3, and its mean value was 227 μg/m3. During the sampling period, 17 fog events occurred and caused a 27% reduction in the mean pre-fog PM2.5 concentration. All the PM and FW samples were analyzed for 12 trace elements: Ca, Cr, Cu, Fe, K, Mg, Mn, Na, Ni, Pb, Zn, V. The concentrations of the various trace elements in the PM1, PM2.5, and FW samples encompassed a wide range: 10 (V)–2432 (Na) ng/m3, 34 (Mn)–13810 (Na) ng/m3, and 8 (Cr)–19870 (Ca) μg/l, respectively. The concentrations of the trace elements in the FW samples indicated a droplet-size-dependent trend: the small droplets (diameter <16 μm) had several times (3–10 times) higher concentrations than the coarser droplets (diameter >22 μm). The enrichment factor (EF) analysis revealed that the EF values for almost all the trace elements were an order of magnitude higher in the FW samples than in PM1 and PM2.5. Risk assessment based on toxic elements suggested a very high inhalation carcinogenic risk (231 per million) for the exposed population during foggy periods. This study will facilitate decision-making by policymakers regarding air quality and health concerns.

“Trace element composition of fine and coarse particles at a background mountain station in Eastern Mediterranean: Assessment aerosol components and their source regions

Components making up aerosol population at a mountain station (1000 m asl) on the Mediterranean coast of Turkey were investigated. Fine (PM2.5) and coarse (PM2.5–10) particle samples were collected at approximately 8 km outside the Marmaris province, on the Mediterranean coast of Turkey. Fifteen elements were measured using energy dispersive x-ray fluorescence (EDXRF) technique. 84%–88% of crustal elements and 48%–51% of anthropogenic elements, except for S, were associated with coarse particles. EFc – Al diagrams showed that relatively high contribution of coarse particles on concentrations of anthropogenic elements is due to coagulation of fine anthropogenic particles on coarse crustal particles. Cluster analysis resulted in seven trajectory clusters. Two of these clusters have potential to bring dust from Sahara and two had potential to bring particles from local sources at western and central parts of Turkey. Concentrations of crustal elements were higher in summer due to limited resuspension in winter. Concentrations of pollution-derived elements were also high in summer due to more effective wet scavenging during winter season. Positive matrix factorization (PMF) analysis resulted in five factors which were identified as sea salt, crustal, local anthropogenic, oil combustion and regional combustion factors. Source regions affecting these anthropogenic components were supported by distributions of PSCF values. Approximately 75% of PM10 mass is accounted for by secondary inorganic ions, crustal material, and sea salt. Dust transported from North Africa accounted for 55%–76% of concentrations of crustal elements, but only 26% of PM10 mass, due to sea salt and secondary ion contribution to PM10 mass concentrations.

Chemical Characterization and Source Apportionment of PM10 Using Receptor Models over the Himalayan Region of India

This study presents the source apportionment of coarse-mode particulate matter (PM10) extracted by 3 receptor models (PCA/APCS, UNMIX, and PMF) at semi-urban sites of the Indian Himalayan region (IHR) during August 2018–December 2019. In this study, water-soluble inorganic ionic species (WSIIS), water-soluble organic carbon (WSOC), carbon fractions (organic carbon (OC) and elemental carbon (EC)), and trace elements of PM10 were analyzed over the IHR. Nainital (62 ± 39 µg m−3) had the highest annual average mass concentration of PM10 (average ± standard deviation at 1 σ), followed by Mohal Kullu (58 ± 32 µg m−3) and Darjeeling (54 ± 18 µg m−3). The annual total ∑WSIIS concentration order was as follows: Darjeeling (14.02 ± 10.01 µg m−3) &gt; Mohal-Kullu (13.75 ± 10.21 µg m−3) &gt; Nainital (10.20 ± 6.30 µg m−3), contributing to 15–30% of the PM10 mass. The dominant secondary ions (NH4+, SO42−, and NO3−) suggest that the study sites were strongly influenced by anthropogenic sources from regional and long-range transport. Principal component analysis (PCA) with an absolute principal component score (APCS), UNMIX, and Positive Matrix Factorization (PMF) were used for source identification of PM10 at the study sites of the IHR. All three models showed relatively similar results of source profiles for all study sites except their source number and percentage contribution. Overall, soil dust (SD), secondary aerosols (SAs), combustion (biomass burning (BB) + fossil fuel combustion (FFC): BB+FFC), and vehicular emissions (VEs) are the major sources of PM10 identified by these models at all study sites. Air mass backward trajectories illustrated that PM10, mainly attributed to dust-related aerosols, was transported from the Thar Desert, Indo-Gangetic Plain (IGP), and northwestern region of India (i.e., Punjab and Haryana) and Afghanistan to the IHR. Transported agricultural or residual burning plumes from the IGP and nearby areas significantly contribute to the concentration of carbonaceous aerosols (CAs) at study sites.

The Relationship of Aerosol Properties and Ice‐Nucleating Particle Concentrations in Beijing

AbstractThis paper investigates immersion mode ice‐nucleating particle (INP) concentrations measured with a continuous flow diffusion chamber at temperatures of −20°C, −25°C, and −30°C in Beijing from 4 May to 4 June 2018. Aerosol conditions in the experiment period are classified into four types: clean, light PM2.5 pollution, heavy PM2.5 pollution, and dust. The PM mass concentrations and the aerosol size distributions are distinctly different in the four aerosol conditions. INP concentration increases as temperature decreases from −20°C to −30°C for all the four aerosol conditions. At a given temperature, INP concentrations progressively increase as the aerosol condition changes from clean to light PM2.5 pollution and to heavy PM2.5 pollution condition. At −25°C and −30°C, the dust condition has a much higher INP concentration than the other aerosol conditions. The INP concentration is closely related to the number concentration of aerosols with diameters of 1.0–2.5 μm (). Using a similar method as in the previous parameterization of INP concentrations for global and fairly clean aerosol conditions, a new parameterization of the INP concentration based on is provided for the complicated aerosol conditions with high aerosol number concentrations in Beijing.

A case study on occupational exposure assessment and characterization of particles in a printing shop in China.

Printers can release numerous particles to contaminate indoor environments and pose health risks. Clarifying the exposure level and physicochemical properties ofprinter-emitted particles (PEPs) will help to evaluate the health risks of printer operator. In our study, the particles concentration in the printing shop was monitored in real time for a long time (12h/day, total 6days), and the PEPs were collected to characterize their physicochemical properties including shape, size and compositions. The result showed that the concentration of PEPs is closely related to the printing workload and the highest particle mass concentration of PM10 and PM2.5 was 212.73μgm-3 and 91.48μgm-3, respectively. The concentration of PM1 in the printing shop was in the range of 11.88-80.59μgm-3 for mass value, and 174.83-1348.84 Pcm-3 for count value which changed with the printing volume. The particle sizes of PEPs were less than 900nm, 47.99% of PEPs was less than 200nm, and 14.21% of the particles were at the nanoscale. PEPs contained 68.92% organic carbon (OC), 5.31% elemental carbon (EC), 3.17% metal elements, and 22.60% other inorganic additives, which contained more OC and metal elements than toners. Total polycyclic aromatic hydrocarbons (PAHs) levels were 18.95ng/mg in toner and 120.70ng/mg in PEPs. The carcinogenic risk of PAHs in PEPs was 1.40 × 10-7. These findings suggested future studies should pay more attention to the health effects of printing workers exposed to nanoparticles.

ЗАГРЯЗНЕНИЕ МОСКОВСКОГО МЕГАПОЛИСА: МОНИТОРИНГ ХИМИЧЕСКОГО СОСТАВА МИКРОЧАСТИЦ В СИСТЕМЕ “АТМОСФЕРА - СНЕГ - ДОРОЖНАЯ ПЫЛЬ - ПОЧВЫ - ПОВЕРХНОСТНЫЕ ВОДЫ”

A methodological framework for a system of ecological and geochemical monitoring of urban landscapes has been developed based on a joint analysis of the chemical composition of microparticles in transit (atmospheric aerosol and precipitation, river water and suspended sediments) and depositing (road dust, snow and soil covers, bottom sediments) environments. For automated monitoring on the territory of the Lomonosov Moscow State University Meteorological Observatory, the Aerosol Complex has been created, and seasonal variations in mass concentrations of PM10, black carbon, metals, metalloids, and polycyclic aromatic hydrocarbons in atmospheric aerosol and precipitation in the Moscow megacity has been analyzed. In the aerosol-precipitation subsystem, a high washout capacity of precipitation with respect to Pb, Sb, As, Ni, Mg, K, Al, and S in the aerosols has been revealed. The enrichment of PM10 with metals and metalloids decreases in the snow-road dust-soil series, and Sb, W, Bi, Sn, Cd, Cu, Pb, Mo, and Zn are accumulated in PM10 in all three environments. The particles of PM10 suspended matter and of the Moskva River bottom sediments play a key role in transport and accumulation of Pb, Cu, Ni, and V.

Online chemical characterization of atmospheric fine secondary aerosols and organic nitrates in summer Nanjing, China

The mechanisms leading to secondary aerosol pollution in the Yangtze Delta region (such as Nanjing) are still poorly constrained. Here we conducted a field campaign to elucidate the chemical characteristics of fine aerosols, with a focus on variations and formation mechanisms of secondary components in summer Nanjing. The average PM1 mass concentration was 18.88 μg m−3 and was dominated by the secondary species (78%). Secondary inorganic species accounted for 30% of PM1 mass and high PM1 loading was closely relevant with nitrate rather than sulfate. Nitrate was mainly produced from nighttime heterogeneous/aqueous process (production rate of 0.38 g/g H2O) and its variation was driven by thermodynamic equilibrium. On the other hand, sulfate was governed by daytime photochemical production (production rate of 0.013 g/g Ox)(Ox=NO2 + O3) while contribution of aqueous process was minor. Positive matrix factorization identified and quantified a traffic-related hydrocarbon OA (HOA), a cooking OA (COA), and four SOA factors including a local secondary OA (LSOA), a less oxygenated OA (LO-OOA), a moderately oxygenated OA (MD-OOA), and a more-oxidized oxygenated OA (MO-OOA). LSOA was likely from local photochemical conversion of HOA and COA; LO-OOA was semi-volatile thus evaporation/diffusion would offset its weak photochemical production. MO-OOA was very clearly linked with photochemistry, based on its afternoon enhancement and tight positive correlations with Ox (0.029 g/g Ox, occupying ∼60% of photochemical SOA production) and sulfate. MD-OOA was a minor contributor of SOA (∼6%) but it was clearly from aqueous process given the strong positive correlation with aerosol liquid water content (ALWC) and nitrate. Both nitrate and MD-OOA concentrations increased against pH while those of sulfate and MO-OOA decreased. We further investigated the organic nitrate (ON) characteristics, and found that ON was a very minor component of OA in summer Nanjing (0.08–0.14 μg m−3, 0.6–1.1% of OA) and it was predominantly associated with aqueous process. Overall, this work reveals in details formation processes of different secondary species, and therefore is insightful for future air pollution modelling and efficient control in similar regions.

Chemical-composition characteristics of PM1 and PM2.5 and effects on pH and light-extinction coefficients under different pollution levels in Zhengzhou, China

Atmospheric particulate matter (PM) is a significant pollutant in the atmosphere. An increase in PM2.5 concentration notably diminishes atmospheric visibility and leads to haze formation. PM1, a type of atmospheric PM with smaller particle size, has a more pronounced effect on visibility and aerosol pH compared to PM2.5. In this study, PM1 and PM2.5 samples were collected in August, November, and December of 2020, as well as in April of 2021 in Zhengzhou. The chemical composition, aerosol pH, and light-extinction coefficients (bext) of PM1 and PM2.5 were analyzed based on the aerosol concentrations in three pollution categories. Throughout the sampling period, the average mass concentrations of PM1 and PM2.5 were 56.2 and 71.9 μg m−3, respectively, with nitrate constituting 24.3% of PM2.5. This highlights the severe submicron-level particulate pollution in Zhengzhou. Differences in the composition of PM1 and PM2.5 led to variations in aerosol water content, but the combined effect on aerosol pH was minimal. PM1 displayed a stronger negative correlation with visibility because SNA (NO3−, SO42−, and NH4+) was primarily concentrated in PM1. The bext of nitrate consistently increased during the pollution period, reaching 58% during the moderate pollution phase. This result suggests that the extinction contribution of nitrate was the main factor contributing to the decreased visibility in Zhengzhou. Reducing nitrogen oxide emissions can lower PM2.5 concentrations and enhance visibility. Additionally, controlling nitrate production can achieve a secondary reduction in aerosol concentration by decreasing the aerosol water content, which in turn reduces the secondary formation of PM. This study is beneficial for formulating measures to reduce the concentration of PM2.5 and reducing pollution.

Firework smoke: Impacts on urban air quality and deposition in the human respiratory system

Particle number concentrations and size distributions resulting from the firework displays held in Budapest, Hungary every year on St. Stephen's Day were studied over a period of seven years. In the year most impacted, the total particle number concentration reached its peak measured level of 369 × 103 cm−3 5 min after the end of the display, and returned to the pre-event state within 45 min. The fireworks increased hourly mean concentrations by a factor of 5–6, whereas the concentrations in the diameter range of 100–1000 nm, in which the magnitude of the increase was the greatest, were elevated by a factor of 20–25. An extra particle size mode at 203 nm was manifested in the size distributions as result of the fireworks. The PM10 mass concentrations at peak firework influence and as 1-h mean increased 123 and 58 times, respectively, relative to the concentration before the display. The smoke was characterised by a relatively short overall atmospheric residence time of 25 min. Spatiotemporal dispersion simulations revealed that there were substantial vertical and horizontal concentration gradients in the firework plume. The affected area made up a large part of the city. Not only the spectators of the display at the venue and nearby areas, but the population located further away downwind of the displays and more distant, large and populous urban quarters were affected by the plume and its fallout. The fireworks increased the deposition rate in the respiratory system of females by a factor of 4, as a conservative estimate. The largest surface density deposition rates were seen in the segmental and sub-segmental bronchi, which represents an excessive risk to health. Compared to adults, children were more susceptible to exposure, with the maximum surface density deposition rates in their case being three times those of adults in the trachea.

Concentrations of PM0.1 and PM2.5 at high polluting event days in Ha Noi and the effects of meteorological conditions

. High levels of fine (PM2.5) and ultrafine (PM0.1) particles in the atmosphere can cause adverse effects on the environment and human health. This study aims at determining the mass concentrations of PM and meteorological influencing factors in high pollution event days in Hanoi. Daily samples of PM2.5 and PM0.1 were collected at a mixed site in Hanoi, Vietnam, from the middle of October to December 2020. High pollution events were determined based on PM2.5 concentrations and analyzed for its average concentration and intensity (number of days). The regression analysis and correlation matrix were determined by R software, version 4.04. Seven high pollution events were recorded for 2.5 sampling months. The daily PM2.5 concentrations were in the range of 19 - 147 µg/m3. Those of PM0.1 varied from 2 to 13 µg/m3 with an average of 6 µg/m3. The investigated meteorological factors can explain 70% PM2.5 variation but only 47% of PM0.1 variations.

Source apportionment of PM10 and health risk assessment related in a narrow tropical valley. Study case: Metropolitan area of Aburrá Valley (Colombia)

This study investigates spatio-temporal variations of PM10 mass concentrations and associated metal(oid)s, δ13C carbon isotope ratios, polycyclic aromatic hydrocarbons (PAHs), total organic carbon (TOC) and equivalent black carbon (eBC) concentrations over a half year period (from March 2017 to October 2017) in two residential areas of Medellín (MED-1 and MED-2) and Itagüí municipality (ITA-1 and ITA-2) at a tropical narrow valley (Aburrá Valley, Colombia), where few data are available. A total of 104 samples were analysed by using validated analytical methodologies, providing valuable data for PM10 chemical characterisation. Metal(oid)s concentrations were measured by inductively coupled plasma mass spectrometry (ICP-MS) after acid digestion, and PAHs concentrations were measured by Gas Chromatography-Mass Spectrometry (GC–MS) after Pressurised Hot Water Extraction (PHWE) and Membrane Assisted Solvent Extraction (MASE). Mean PM10 mass concentration ranged from 37.0 µg m−3 to 45.7 µg m−3 in ITA-2 and MED-2 sites, respectively. Al, Ca, Mg and Na (from 6249 ng m−3 for Mg at MED-1 site to 10,506 ng m−3 for Ca at MED-2 site) were the major elements in PM10 samples, whilst As, Be, Bi, Co, Cs, Li, Ni, Sb, Se, Tl and V were found at trace levels (< 5.4 ng m−3). Benzo[g,h,i] perylene (BghiP), benzo[b + j]fluoranthene (BbjF) and indene(1,2,3-c,d)pyrene (IcdP) were the most profuse PAHs in PM10 samples, with average concentrations of 0.82–0.86, 0.60–0.78 and 0.47–0.58 ng m−3, respectively. Results observed in the four sampling sites showed a similar dispersion pattern of pollutants, with temporal fluctuations which seems to be associated to the meteorology of the valley. A PM source apportionment study were carried out by using the positive matrix factorization (PMF) model, pointing to re-suspended dust, combustion processes, quarry activity and secondary aerosols as PM10 sources in the study area. Among them, combustion was the major PM10 contribution (accounting from 32.1 to 32.9% in ITA-1 and ITA-2, respectively), followed by secondary aerosols (accounting for 13.2% and 23.3% ITA-1 and MED-1, respectively). Finally, a moderate carcinogenic risk was observed for PM10-bound PAHs exposure via inhalation, whereas significant carcinogenic risk was estimated for carcinogenic metal(oid)s exposure in the area during the sampling period.

Real time measurements of the secondary organic aerosol formation and aging from ambient air using an oxidation flow reactor in seoul during winter

Herein, the formation and aging processes of organic aerosol (OA) in urban Seoul, Korea, during winter were investigated using a high-resolution aerosol mass spectrometer (HR-ToF-AMS) and an oxidation flow reactor (OFR). The results demonstrated that the highest secondary OA (SOA) production (ΔOA = 3.44 μg m−3 with a relative OA enhancement ratio (EROA) = 1.40) occurred at ∼2 eq. days of OH exposure. Particularly, higher SOA production was observed under the following atmospheric conditions: high relative humidity (RH) (>70%) and high PM1 mass concentration (>50 μg m−3), demonstrating that oxidation capacity, heterogeneous and aqueous phase reactions are important for further oxidation. Additionally, increased SOA formation occurs under both higher hydrocarbon-like OA and more oxidized OOA conditions. Further oxidation of both freshly emitted and aged and/or transported OA can be a remarkable further source of SOA in winter in Seoul and further downwind areas. In particular, the high mass concentration of MO-OOA in high total PM1 would be an important indication that SOA formation could be accelerated by a heterogeneous reaction, necessitating additional investigations on the haze formation process.

Critical aspects in occupational exposure assessment with different aerosol metrics in an industrial spray coating process

Engineered Nanomaterials (ENMs) have several uses in various industrial fields and are embedded in a myriad of consumer products. However, there is continued concern over the potential adverse health effects and environmental impacts of ENMs due to their unique physico-chemical characteristics. Currently, there are no specific international regulations for various ENMs. There are also no Occupational Exposure Limits (OEL) regulated by the European Union (EU) for nanomaterials in the form of nano-objects, their aggregates or agglomerates (NOAA). For ENMs the question of which metric to be used (i.e., mass, surface area, number concentrations) to determine the exposure is still not resolved. The aim of this work is to assess the worker exposure by inhalation in an industrial spray coating process by using all three metrics mentioned above. Two target ENMs (N-doped TiO2, TiO2N and AgNPs capped with a quaternized hydroxyethyl-cellulose, AgHEC) generated for industrial-scale spraying processes were considered. Results showed that the averaged particle number concentration (10–100 nm) was below 2.7 104 cm−3 for both materials. The Lung Deposited Surface Area (LDSA) was in the range between 73 and 98 μm2cm−3 and the particle mass concentration (obtained by means of ICP-EOS off-line analysis) resulted below 70 μg m−3 and 0.4 μg m−3 for TiO2 and Ag, respectively. Although, the airborne particles concentration compared well with the NIOSH Recommended Exposure Level (REL) limits the contribution to the background, according to EN 17058 (Annex E) was significant (particularly in the particle number and PM1 mass concentrations). We successfully evaluated the worker exposure by means of the different airborne particles' metrics (number, surface and mass concentrations). We concluded that worker exposure assessment involving ENMs is a complex procedure with requires both real time and off-line measurements and a deep investigation of the background.

Marine Submicron Aerosols from the Gulf of Mexico: Polluted and Acidic with Rapid Production of Sulfate and Organosulfates.

We measured submicron aerosols (PM1) at a beachfront site in Texas in Spring 2021 to characterize the "background" aerosol chemical composition advecting into Texas and the factors controlling this composition. Observations show that marine "background" aerosols from the Gulf of Mexico were highly processed and acidic; sulfate was the most abundant component (on average 57% of total PM1 mass), followed by organic material (26%). These chemical characteristics are similar to those observed at other marine locations globally. However, Gulf "background" aerosols were much more polluted; the average non-refractory (NR-) PM1 mass concentration was 3-70 times higher than that observed in other clean marine atmospheres. Anthropogenic shipping emissions over the Gulf of Mexico explain 78.3% of the total measured "background" sulfate in the Gulf air. We frequently observed haze pollution in the air mass from the Gulf, with significantly elevated concentrations of sulfate, organosulfates, and secondary organic aerosol associated with sulfuric acid. Analysis suggests that aqueous oxidation of shipping emissions over the Gulf of Mexico by peroxides in the particles might potentially be an important pathway for the rapid production of acidic sulfate and organosulfates during the haze episodes under acidic conditions.

Interannual evolution of the chemical composition, sources and processes of PM2.5 in Chengdu, China: Insights from observations in four winters

The air quality in China has improved significantly in the last decade and, correspondingly, the characteristics of PM2.5 have also changed. We studied the interannual variation of PM2.5 in Chengdu, one of the most heavily polluted megacities in southwest China, during the most polluted season (winter). Our results show that the mass concentrations of PM2.5 decreased significantly year-by-year, from 195.8 ± 91.0 µg/m3 in winter 2016 to 96.1 ± 39.3 µg/m3 in winter 2020. The mass concentrations of organic matter (OM), SO42−, NH4+ and NO3− decreased by 49.6%, 57.1%, 49.7% and 28.7%, respectively. The differential reduction in the concentrations of chemical components increased the contributions from secondary organic carbon and NO3− and there was a larger contribution from mobile sources. The contribution of OM and NO3− not only increased with increasing levels of pollution, but also increased year-by-year at the same level of pollution. Four sources of PM2.5 were identified: combustion sources, vehicular emissions, dust and secondary aerosols. Secondary aerosols made the highest contribution and increased year-by-year, from 40.6% in winter 2016 to 46.3% in winter 2020. By contrast, the contribution from combustion sources decreased from 14.4% to 8.7%. Our results show the effectiveness of earlier pollution reduction policies and emphasizes that priority should be given to key pollutants (e.g., OM and NO3−) and sources (secondary aerosols and vehicular emissions) in future policies for the reduction of pollution in Chengdu during the winter months.

Urban particulate water-soluble organic matter in winter: Size-resolved molecular characterization, role of the S-containing compounds on haze formation

Water-soluble organic matter (WSOM), as a group of ubiquitous components in atmospheric PM, plays a crucial role in global climate change and carbon cycle. In this study, the size-resolved molecular characterization of WSOM in the range of 0.010–18 μm PM was studied to gain insights into their formation processes. The CHO, CHNO, CHOS, CHNOS compounds were identified by the ultrahigh-resolution Fourier transform ion cyclotron resonance mass spectrometry in ESI source mode. A bimodal pattern of the PM mass concentrations was found in the accumulation and coarse mode. The increasing mass concentration of PM was mainly attributed to the growth of large-size PM with the occurrence of haze. Both Aiken-mode (70.5–75.6 %) and coarse-mode (81.7–87.9 %) particles were proven the main carriers of the CHO compounds, the majority of which were indicated to be the saturated fatty acids and their oxidized derivatives. The S-containing (CHOS and CHNOS) compounds in accumulation-mode (71.5–80.9 %) increased significantly in hazy days, where organosulfates (C11H20O6S, C12H22O7S) and nitrooxy-organosulfates (C9H19NO8S, C9H17NO8S) were confirmed in majority. The S-containing compounds in accumulation-mode particle with high oxygen content (6–8 oxygen atoms), unsaturation degree (DBE < 4), and reactivity could facilitate the particle agglomeration and accelerate the haze formation.

Distribution characteristics and optical properties of carbonaceous aerosol: brown carbon and black carbon in Nanchang, inland China

PM2.5 samples were collected from October 31, 2019, to November 10, 2019, in Nanchang for 10 consecutive days. The mass concentrations of PM2.5 and carbon components were measured, and the distribution characteristics of carbonaceous aerosols were discussed. The optical properties of carbonaceous aerosols were quantified by the thermal-optical method and solvent extraction method, respectively. The results showed that the average concentrations of organic carbon (OC) and elemental carbon (EC) in aerosols in Nanchang were 11.79 ± 3.86 and 3.51 ± 1.59 μg m−3, respectively. The average OC/EC was 3.62, and OC2, OC3, OC4 and EC1 accounted for relatively large proportions (19.55, 24.96, 22.37 and 17.38%). Carbonaceous aerosols in Nanchang were greatly affected by coal combustion, vehicle exhaust emissions and secondary organic carbon (SOC) formation. For particulate brown carbon (BrC), the average light absorption coefficient (babs) and mass absorption efficiency (MAE) at 405 nm were 16.87 Mm−1 and 1.49 m2g−1, respectively. The average Absorption Ångström exponent (AAE) was 8.58. For water-soluble organic carbon (WSOC) and methanol-soluble organic carbon (MSOC), the average babs,365,WSOC and babs,365,MSOC were 14.79 and 22.51 Mm−1, respectively. The mean values of AAE300-600,WSOC and AAE300-600,MSOC were 4.17 and 4.84, respectively. The mean MAE365,WSOC and MAE365,MSOC were 1.83 and 2.18 m2 g−1, respectively. The mean value of MAEBC at 405 nm was 10.28 m2 g−1. The optical properties of particulate BrC and dissolved BrC were similar at 405 nm. The light absorption of BrC cannot be ignored, although BC was the main light absorption component.

Carcinogenic Activity and Risk Assessment of PAHs in Ambient Air: PM10 Particle Fraction and Bulk Deposition

This paper present seasonal variation in the equivalent concentration (BaPeq) of PAHs in order to assess the potential cancer risk for two different groups of residents via ingestion, dermal contact and inhalation pathways. The possible ecological risk caused by PAH atmospheric deposition based on risk quotient was also estimated. A bulk (total, wet and dry) deposition and PM10 particle fraction (particles with an equivalent aerodynamic diameter < 10 µm) were collected from June 2020 to May 2021 at an urban residential location in the northern part of Zagreb, Croatia. The monthly average of total equivalent BaPeq mass concentrations of PM10 varied from 0.057 ng m-3 in July to 3.656 ng m-3 in December; the annul ∑BaPeq average was 1.348 ng m-3. In bulk deposition, ∑BaPeq mass concentrations varied from 1.94 to 57.60 ng L-1. In both investigated media, BaP had the highest contribution in carcinogenic activity. For PM10 media, dermal absorption implied the greatest potential cancer risk, followed by ingestion and inhalation. For bulk media, a moderate ecological risk for BaA, BbF and BaP was observed according to the risk quotient approach.

Secondary formation and source analysis of carbonaceous components in PM1 in a typical city, Southwest of China

Carbonaceous components are major components of PM1, which have a significant impact on climate change, air quality and human health. However, the secondary formation and source analysis of carbonaceous components in PM1 are still unclear. Therefore, in order to study the secondary formation and sources of carbonaceous components in PM1, PM1 samples were collected in Chengdu, a typical city located in southwest of China, from 2018 to 2019. The concentrations of organic carbon (OC), elemental carbon (EC) and isotopic compositions of carbon (δ13C) in PM1 were determined using a thermal/optical carbon analyzer and elemental analyzer-isotope ratio mass spectrometer. In addition, the δ13C values from relevant potential sources (C3 plants, C4 plants, vehicle exhaust and coal) were also determined. The results showed that the annual average concentrations of OC and EC in PM1 in Chengdu were 6.43 ± 3.30 μg·m−3 and 1.99 ± 0.98 μg·m−3, accounting for 13.83% and 4.28% of the PM1 mass concentration, respectively. The concentrations of OC in PM1 ranked in the order of winter > summer > spring > autumn, while the concentrations of EC varied in the order of winter > spring > autumn > summer. The concentrations of OC and EC in PM1 reached the maximum in winter, mainly due to the special meteorological conditions and significantly higher pollutant emissions. The correlations of OC and EC were higher in spring, autumn and winter, and lower in summer. It showed that OC and EC might have the same sources in spring, autumn and winter, while the sources of OC and EC were relatively complex in summer. The annual average concentration of secondary organic carbon (SOC) in PM1 was 2.23 ± 1.22 μg·m−3. The concentrations of SOC were higher in autumn and winter and lower in spring and summer. The special meteorological conditions and significantly higher pollutant emissions are important reasons for the higher SOC concentrations in winter. On the other hand, the low temperature in winter can also promote the formation of SOC. The results of carbon isotopic compositions indicated that the carbonaceous components in PM1 were mainly derived from vehicle exhaust (52.4%), C3 plants combustion (26.2%), coal burning (16.2%) and C4 plants combustion (5.2%). The findings help to deepen the understanding of the secondary formation and sources of carbonaceous components in PM1 and provide theoretical guidance for environmental management.

Determination of atmospheric aerosol components in an urban area to evaluate the air quality and identify the sources of contamination.

The need to generate objective evidence and reliable information for decision makers to improve environmental policies for a better air quality, led us to evaluate the atmospheric aerosol components in the urban area of Carabayllo, by monitoring PM2.5 and PM10 to determine mass concentration and analyzing PM10 using k 0-INAA and ICP-MS for metals quantification, ion chromatography for anions and the NIOSH method to determine organic and elemental carbon. The results obtained from mass concentration of PM2.5 and PM10 exceeded the permissible breathing annual average of WHO guidelines of 15µgm-3 and 45µgm-3, respectively, which evidence an unhealthy air quality. Likewise, using the model Positive Matrix Factorization five sources of pollutants were defined: metallurgical industry, sea salt, industrial activity, dust and non-exhaust emissions and vehicle emissions.