Search

We report details of a proficiency testing (PT) scheme for laboratories undertaking the analysis of diesel engine particulates (DEP) collected on workplace air filter samples. Within this occupational hygiene setting, the established approach is to measure the elemental carbon (EC) content within DEP as a specific marker of workers' exposure to engine emissions. Measuring EC is undertaken in laboratories using combustion-based analysers. To date six, PT rounds have been completed with participation ranging between thirteen and twenty-three laboratories. In each round participants received four quartz fibre filter samples (plus blank filters) loaded with DEP with indicative EC mass loadings in the range 9–204 µg/filter. Round assigned values and standard deviation for performance assessment values were calculated by consensus from returned participant data following outlier removal. On this basis, it was determined that on average 81 % of the returned data was deemed satisfactory, i.e. returning a z (or z') score ≤ 2. The use of two operationally defined analytical protocols, namely NIOSH 5040 and EN 16909, now dominate but they give different EC values so the preparation of reference air filter samples with preordained EC values determined using both protocols for use in future interlaboratory comparisons is therefore recommended. [ABSTRACT FROM AUTHOR]

Aims Methods and results Conclusion Long‐term fine particulate matter (PM2.5) exposure has been linked to incident heart failure (HF), but the impacts of its constituents remain unknown. We aimed to investigate the associations of PM2.5 constituents with incident HF, and further evaluate the modification effects of genetic susceptibility.PM2.5 and its constituents, including elemental carbon (EC), organic matter (OM), ammonium (NH4+), nitrate (NO3−), and sulfate (SO42−), were estimated using the European Monitoring and Evaluation Programme model applied to the UK (EMEP4UK) driven by Weather and Research Forecast model meteorology. A polygenic risk score (PRS) was calculated to represent genetic susceptibility to HF. We employed Cox models to evaluate the associations of PM2.5 constituents with incident HF. Quantile‐based g‐computation model was used to identify the main contributor of PM2.5 constituents. Among 411 807 individuals in the UK Biobank, 7554 participants developed HF during a median follow‐up of 12.05 years. The adjusted hazard ratios of HF for each interquartile range increase in PM2.5, EC, OM, NH4+, NO3−, and SO42− were 1.50 (1.46–1.54), 1.31 (1.27–1.34), 1.12 (1.09–1.15), 1.42 (1.41–1.44), 1.26 (1.23–1.29), and 1.25 (1.24–1.26), respectively. EC (43%) played the most important role, followed by NH4+ and SO42−. Moreover, synergistic additive interactions accounted for 9–16% of the HF events in individuals exposed to both PM2.5, NH4+, NO3−, and SO42− and PRS.Long‐term exposure to PM2.5 constituents may elevate HF risk, and EC was the major contributor. Additive effects of PM2.5 constituents and PRS on HF risk were revealed. [ABSTRACT FROM AUTHOR]

Diesel engine exhaust (DEE) is carcinogenic and potentially hazardous for those working in close proximity to diesel-powered machines. This study characterizes workplace exposure to DEE and its associated particulate matter (PM) during outdoor construction activities. We sampled at 4 construction sites in the Copenhagen metropolitan area. We used portable constant-flow pumps and quartz-fiber filters to quantify personal exposure to elemental carbon (EC), and used real-time instruments to collect activity-based information about particle number and size distribution, as well as black carbon (BC) concentration. Full-shift measurements of EC concentration ranged from < 0.3 to 6.4 µg/m3. Geometric mean (GM) EC exposure was highest for ground workers (3.4 µg/m3 EC; geometric standard deviation, GSD = 1.3), followed by drilling rig operators (2.6 µg/m3 EC; GSD = 1.4). Exposure for non-drilling-rig machine operators (1.2 µg/m3 EC; GSD = 2.9) did not differ significantly from background (0.9 µg/m3 EC; GSD = 1.7). The maximum 15-min moving average concentration of BC was 17 µg/m3, and the highest recorded peak concentration was 44 µg/m3. In numbers, the particle size distributions were dominated by ultrafine particles ascribed to DEE and occasional welding activities at the sites. The average total particle number concentrations (PNCs) measured in near-field and far-field positions across all worksites were 10,600 (GSD = 3.0) and 6,000 (GSD = 2.8)/cm3, respectively. Sites with active drilling rigs saw significantly higher average total PNCs at their near-field stations (13,600, 32,000, and 9,700/cm3; GSD = 2.4, 3.4, and 2.4) than sites without (4,700/cm3; GSD = 1.6). Overall, the DEE exposures at these outdoor construction sites were below current occupational exposure limits for EC (10 µg/m3 in Denmark; 50 µg/m3 in the European Union), but extended durations of exposure to the observed DEE levels may still be a health risk. [ABSTRACT FROM AUTHOR]

Sarcoidosis is a chronic granulomatous disease predominantly affecting the lungs and inducing significant morbidity and elevated mortality rate. The etiology of the disease is unknown but may involve exposure to an antigenic agent and subsequent inflammatory response resulting in granuloma formation. Various environmental and occupational risk factors have been suggested by previous observations, such as moldy environments, insecticides, and bird breeding. Our study investigated the association of air pollution with diagnosis of sarcoidosis using a case-control design. Penn State Health electronic medical records from 2005 to 2018 were examined for adult patients with (cases) and without (controls) an International Classification of Disease (ICD)-9 or −10 code for sarcoidosis. Patient addresses were geocoded and 24-hr residential-level air pollution concentrations were estimated using spatio-temporal models of particulate matter <2.5 μm (PM2.5), ozone, and PM2.5 elemental carbon (EC) and moving averages calculated. In total, 877 cases and 34,510 controls were identified. Logistic regression analysis did not identify significant associations between sarcoidosis incidence and air pollution exposure estimates. However, the odds ratio (OR) for EC for exposures occurring 7–10 years prior did approach statistical significance, and ORs exhibited an increasing trend for longer averaging periods. Data suggested a latency period of more than 6 years for PM2.5 and EC for reasons that are unclear. Overall, results for PM2.5 and EC suggest that long-term exposure to traffic-related air pollution may contribute to the development of sarcoidosis and emphasize the need for additional research and, if the present findings are substantiated, for public health interventions addressing air quality as well as increasing disease surveillance in areas with a large burden of PM2.5 and EC. [ABSTRACT FROM AUTHOR]

The overarching goal of this study is to effect the elimination of platinum from adducts with cis –C≡C−Pt−C≡C‐ linkages, thereby generating novel conjugated polyynes. Thus, the bis(hexatriynyl) complex trans‐(p‐tol3P)2Pt((C≡C)3H)2 is treated with 1,3‐diphosphines R2C(CH2PPh2)2 to generate (R2C(CH2PPh2)2)2Pt((C≡C)3H)2 (14; R=c, n‐Bu; e, p‐tolCH2). These condense with the diiodide complexes R2C(CH2PPh2)2PtI2 (9 a,c) in the presence of CuI (cat.) and excess HNEt2 to give the title macrocycles [(R2C(CH2PPh2)2)Pt(C≡C)3]4 (16 c,e) as adducts of the byproduct [H2NEt2]+ I− (30–66 %). DOSY NMR experiments establish that this association is maintained in solution, but NaOAc removes the ammonium salt. The bis(triethylsilylpolyynyl) complexes (n‐Bu2C(CH2PPh2)2)Pt((C≡C)nSiEt3)2 (n=2, 3) are synthesized analogously to 14 c. They react with I2 at rt to give mainly the diiodide complex 9 c and the coupling product Et3Si(C≡CC≡C)nSiEt3. The possibility of competing reactions giving IC≡C species is investigated. Analogous reactions of the Pt4C24 macrocycle 16 c also give 9 c, but no sp 13C NMR signals or mass spectrometric Cxz+ ions (x=24–100) could be detected. It is proposed that some cyclo[24]carbon is generated, but then rapidly converts to other forms of elemental carbon. No cyclotetracosane (C24H48) is detected when this sequence is carried out in the presence of PtO2 and H2. [ABSTRACT FROM AUTHOR]

Four hundred and sixty-six references with 625 data reports were included in our study. The high frequency of ratio OC/EC for PM0.1 was observed in 3.92–5.93; PM1 in 1.08–3.08; PM2.5, 2.08–4.08; PM10 in 2.70–4.70 and TSP in 2.66–4.66. The rank order of areas based on the pooled concentration of OC bound to PM2.5 was traffic (17.893 µg/m3) > industrial (10.58 µg/m3) > urban (7.696 µg/m3) > rural (4.08 µg/m3). The rank order of areas based on the pooled (mean) concentration of EC in PM2.5 was traffic (17.893 µg/m3) > industrial (2.65 µg/m3) > Urban (1.48 µg/m3) > rural (1.06 µg/m3). The pooled concentrations of OC and EC bound to PM2.5 in traffic areas were higher than in other areas. Therefore, it is recommended that monitoring and effectively reducing concentration plans are carried out, especially in traffic areas. [ABSTRACT FROM AUTHOR]

Background: Epidemiological and toxicological studies indicate that increased exposure to air pollutants can lead to neurodegenerative diseases. To further confirm this relationship, we evaluated the association between exposure to ambient air pollutants and corneal nerve measures as a surrogate for neurodegeneration, using corneal confocal microscopy. Methods: We used population-based observational cross-sectional data from The Maastricht Study including N = 3635 participants (mean age 59.3 years, 51.6% were women, and 19.9% had type 2 diabetes) living in the Maastricht area. Using the Geoscience and hEalth Cohort COnsortium (GECCO) data we linked the yearly average exposure levels of ambient air pollutants at home address-level [particulate matter with diameters of ≤ 2.5 µm (PM2.5), and ≤ 10.0 µm (PM10), nitrogen dioxide (NO2), and elemental carbon (EC)]. We used linear regression analysis to study the associations between Z-score for ambient air pollutants concentrations (PM2.5, PM10, NO2, and EC) and Z-score for individual corneal nerve measures (corneal nerve bifurcation density, corneal nerve density, corneal nerve length, and fractal dimension). Results: After adjustment for potential confounders (age, sex, level of education, glucose metabolism status, corneal confocal microscopy lag time, inclusion year of participants, smoking status, and alcohol consumption), higher Z-scores for PM2.5 and PM10 were associated with lower Z-scores for corneal nerve bifurcation density, nerve density, nerve length, and nerve fractal dimension [stβ (95% CI): PM2.5 -0.10 (-0.14; -0.05), -0.04 (-0.09; 0.01), -0.11 (-0.16; -0.06), -0.20 (-0.24; -0.15); and PM10 -0.08 (-0.13; -0.03), -0.04 (-0.09; 0.01), -0.08 (-0.13; -0.04), -0.17 (-0.21; -0.12)], respectively. No associations were found between NO2 and EC and corneal nerve measures. Conclusions: Our population-based study demonstrated that exposure to higher levels of PM2.5 and PM10 are associated with higher levels of corneal neurodegeneration, estimated from lower corneal nerve measures. Our results suggest that air pollution may be a determinant for neurodegeneration assessed in the cornea and may impact the ocular surface health as well. [ABSTRACT FROM AUTHOR]

Abstract Background Epidemiological and toxicological studies indicate that increased exposure to air pollutants can lead to neurodegenerative diseases. To further confirm this relationship, we evaluated the association between exposure to ambient air pollutants and corneal nerve measures as a surrogate for neurodegeneration, using corneal confocal microscopy. Methods We used population-based observational cross-sectional data from The Maastricht Study including N = 3635 participants (mean age 59.3 years, 51.6% were women, and 19.9% had type 2 diabetes) living in the Maastricht area. Using the Geoscience and hEalth Cohort COnsortium (GECCO) data we linked the yearly average exposure levels of ambient air pollutants at home address-level [particulate matter with diameters of ≤ 2.5 µm (PM2.5), and ≤ 10.0 µm (PM10), nitrogen dioxide (NO2), and elemental carbon (EC)]. We used linear regression analysis to study the associations between Z-score for ambient air pollutants concentrations (PM2.5, PM10, NO2, and EC) and Z-score for individual corneal nerve measures (corneal nerve bifurcation density, corneal nerve density, corneal nerve length, and fractal dimension). Results After adjustment for potential confounders (age, sex, level of education, glucose metabolism status, corneal confocal microscopy lag time, inclusion year of participants, smoking status, and alcohol consumption), higher Z-scores for PM2.5 and PM10 were associated with lower Z-scores for corneal nerve bifurcation density, nerve density, nerve length, and nerve fractal dimension [stβ (95% CI): PM2.5 -0.10 (-0.14; -0.05), -0.04 (-0.09; 0.01), -0.11 (-0.16; -0.06), -0.20 (-0.24; -0.15); and PM10 -0.08 (-0.13; -0.03), -0.04 (-0.09; 0.01), -0.08 (-0.13; -0.04), -0.17 (-0.21; -0.12)], respectively. No associations were found between NO2 and EC and corneal nerve measures. Conclusions Our population-based study demonstrated that exposure to higher levels of PM2.5 and PM10 are associated with higher levels of corneal neurodegeneration, estimated from lower corneal nerve measures. Our results suggest that air pollution may be a determinant for neurodegeneration assessed in the cornea and may impact the ocular surface health as well.

Radiocarbon measurements on the carbonaceous aerosol fractions are an effective tool for aerosol source apportionment. For these measurements, a new sample preparation line (MISSMARPLE: MIlan Small-SaMple Automated Radiocarbon Preparation LinE for atmospheric aerosol) was built in Milan (Italy). MISSMARPLE can separate different carbon fractions (i.e. total carbon (TC), elemental carbon (EC)), automates the sample combustion processes and the CO2 isolation in the "combustion line", and was designed to handle small samples, of about 50 μg carbon. The CO2 obtained in the combustion line is then reduced to graphite in the graphitization line for subsequent accelerator mass spectrometry (AMS) analysis at the INFN-LABEC in Sesto Fiorentino (Italy). MISSMARPLE was tested for reproducibility of 14C/12C ratio in primary standard samples, for background contamination by the analysis of blank samples (graphite with zero percent Modern Carbon (pMC)), and for accuracy by the analysis of IAEA-C7 for pMC(TC) and NIST RM8785 for pMC(EC) used as secondary standards. Measurements were carried out in different AMS runs. Reproducibility of 14C/12C was within 1.2%; blank values were down to 2.2 ± 0.2 pMC in the latest AMS run, and both IAEA-C7 and NIST RM8785 measurements were within 1σ with the reference value (but for one IAEA-C7 sample within 2.3σ). These results point to MISSMARPLE as a new, valuable tool for aerosol sample preparation for radiocarbon measurements to be exploited not only on traditional 24-h samples but also when small carbon quantities are available (e.g. collected at remote sites or with high temporal resolution). [ABSTRACT FROM AUTHOR]

Copyright of Arid Zone Research / Ganhanqu Yanjiu is the property of Arid Zone Research Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The Italian Interministerial Decree of February 11, 2021, introduces the diesel engine exhaust (DDE) among the carcinogenic occupational compounds, also establishing an occupational exposure limit. Elemental carbon (EC), improperly called black carbon, has been proposed as a tracer of DDE exposure; EC is the carbon that is quantified in the ambient matrixes after all the organic carbon has been removed; traditionally, EC is measured with a thermo-optical analytical technique. EC determination and relative interpretation are challenging for the following reasons: (i) the scarce availability of equipped laboratories hampers EC analysis, (ii) EC interpretation is not easy due to the lack of reference values. Finally, (iii) the limit value of 0.050 mg/m³ of EC in the workplace appears too high compared to recently published exposure data. All these aspects stimulate a reflection on the significance of EC data in the context of both occupational hygiene and occupational medicine. [ABSTRACT FROM AUTHOR]

To evaluate carbonaceous components in the ambient air in the eastern region of Indonesia, 35 Total Suspended Particulate Matter (TSP) samples were collected on four characteristic roadsides on Sultan Alauddin Street, in Makassar City, using a high-volume air sampler. The average TSP concentration was 279.7 μg/m3, which exceeded both the National Ambient Air Quality Standard (NAAQS) of Indonesia and the World Health Organization (WHO) standards. The highest concentration reached 838.6 μg/m3 in the GR (gravel) site, which had the highest number of vehicles and was near a U-turn. TSP concentration was higher during peak hours (morning and late afternoon) than off-peak hours (noon). The main component of the total carbon (TC) fraction was organic carbon (OC), which showed a strong correlation with elemental carbon (EC) (r values for the morning, noon, and late afternoon were 0.89, 0.87, and 0.97, respectively), indicating that the carbon components were derived from common sources. TSP had a strong correlation with carbon components, except for char-EC. OC vs. soot-EC and EC vs. soot-EC also correlated well, suggesting the dominant influence of vehicle exhaust emissions. Non-exhaust emissions had a slight influence during peak hours, particularly at the GR site. [ABSTRACT FROM AUTHOR]

We present the results of trajectory analysis of long-term measurements of organic (OC) and elemental (EC) carbon in aerosols sampled on quartz filters at an altitude of 300 m at ZOTTO station. The EC and OC concentrations were determined by the thermo-optical method. The resulted time series were supplemented with the HYSPLIT backward trajectories, and CWT and PSCF functions were calculated on a grid of 150 × 250 cells, which covered the geographical area of 30° × 20° centered at Zotino. These functions characterize the intensity of potential sources of carbon-containing aerosols in a cell. The results make it possible to identify the regions with the strongest organic and elemental carbon emissions and to estimate the seasonal variability of these emissions. In particular, in summer, the main sources of OC and EC are located to the east of Zotino, in the Podkamennaya Tunguska River region, and are most likely associated with wildfires. In cold seasons, most sources of carbonaceous aerosols are in the southwestern part of the geographical region under study, where large cities are located and the bulk of the population is concentrated. The regression analysis of CWT functions of organic and elemental carbon is shown to enable determining the dominant type of carbonaceous aerosol sources in some cases. Our results can be used for estimation of aerosol radiative forcing in Siberia. [ABSTRACT FROM AUTHOR]

In recent years, the rising levels of atmospheric particulate matter (PM) have an impact on the earth's system, leading to undesirable consequences on various aspects like human health, visibility, and climate. The present work is carried out over an insufficiently studied but polluted urban area of Peshawar, which lies at the foothills of the famous Himalaya and Karakorum area, Northern Pakistan. The particulate matter with an aerodynamic diameter of less than 10 µm, i.e., PM10 are collected and analyzed for mineralogical, morphological, and chemical properties. Diverse techniques were used to examine the PM10 samples, for instance, Fourier transform infrared spectroscopy, x-ray diffraction, and scanning electron microscopy along with energy-dispersive x-ray spectroscopy, proton-induced x-ray emission, and an OC/EC carbon analyzer. The 24 h average PM10 mass concentration along with standard deviation was investigated to be 586.83 ± 217.70 µg/m3, which was around 13 times greater than the permissible limit of the world health organization (45 µg/m3) and 4 times the Pakistan national environmental quality standards for ambient PM10 (150 µg/m3). Minerals such as crystalline silicate, carbonate, asbestiform minerals, sulfate, and clay minerals were found using FTIR and XRD investigations. Microscopic examination revealed particles of various shapes, including angular, flaky, rod-like, crystalline, irregular, rounded, porous, chain, spherical, and agglomeration structures. This proved that the particles had geogenic, anthropogenic, and biological origins. The average value of organic carbon, elemental carbon, and total carbon is found to be 91.56 ± 43.17, 6.72 ± 1.99, and 102.41 ± 44.90 µg/m3, respectively. Water-soluble ions K+ and OC show a substantial association (R = 0.71). Prominent sources identified using Principle component analysis (PCA) are anthropogenic, crustal, industrial, and electronic combustion. This research paper identified the potential sources of PM10, which are vital for preparing an air quality management plan in the urban environment of Peshawar. [ABSTRACT FROM AUTHOR]

Environmental context: Carbonaceous components in PM2.5 have a negative effect on the environment, human health and climate. We explored the pollution characteristic, potential sources and interaction of carbonous aerosols in two adjacent areas in Shanxi, China. The concentration levels of organic carbon and elemental carbon were of a moderate level of all those measured between 2009 and 2020. Vehicle exhaust and coal combustion were the two main sources, and Yuci may be affected by the regional transport of Taiyuan in winter. Rationale: Carbonaceous aerosols seriously affect people's health and have a strong scattering effect on visible light. Pollution cuased by carbonaceous components in Taiyuan is serious. Numerous universities in Taiyuan have been moving to Yuci college town since 2013, and the amount of organic pollutants has increased gradually with the growing population. It is necessary to study the characteristics and relationship of carbonaceous aerosols in these two adjacent areas. Methodology: PM2.5 samples were collected in Taiyuan and Yuci college town in 2017 and 2018, and eight carbonaceous components were analysed using a Sunset Laboratory analyser. Pollution characteristic, potential sources and interaction of carbonous aerosols in the two adjacent areas were investigated. Results: The average organic carbon (OC) and elemental carbon (EC) concentrations were 12.6 and 6.8 µg m−3 in Taiyuan and 11.7 and 6.9 µg m−3 in Yuci. The OC and EC concentrations in Taiyuan can be approximately divided into three levels between 2009 and 2020, and the OC and EC levels in Taiyuan studied here (2017 and 2018) were in the middle level. The OC and EC concentrations were higher when the temperature was lower. Discussion: The OC concentration in December was the highest among three winter periods, which may be caused by secondary organic carbon formation related to the lower temperature and an inversion layer. Four source categories were identified using positive matrix factorisation, namely secondary source (25.0%), dust source (16.6%), vehicle exhaust (27.0%) and coal combustion (31.4%). In Taiyuan and Yuci, the trajectory clusters were mainly from north-west and west in winter, whereas the air masses not only originated from north-west, but also north and south in autumn. Yuci may be affected by Taiyuan's regional transport in winter. The results clarify the characteristics of carbon aerosols in the two adjacent areas, and provide fundamental data for the prevention and control of regional air pollutants. Environmental context. Carbonaceous components in PM2.5 have a negative effect on the environment, human health and climate. We explored the pollution characteristic, potential sources and interaction of carbonous aerosols in two adjacent areas in Shanxi, China. The concentration levels of organic carbon and elemental carbon were of a moderate level of all those measured between 2009 and 2020. Vehicle exhaust and coal combustion were the two main sources, and Yuci may be affected by the regional transport of Taiyuan in winter. [ABSTRACT FROM AUTHOR]

Air pollution, particularly in urban and industrial areas, is affecting human health. Dust particles in the air are mostly composed of carbon particles, either organic carbon (OC) or elemental carbon (EC). In this study, carbon compositions of PM2.5 in different land use categories by Bangkok Metropolitan Region (BMR) were evaluated. A sampling was carried out using the gravimetric method. The samples were analyzed for their organic and elemental carbon composition using thermal optical analysis following the U.S. EPA IMPROVE-A. The results indicate that organic carbon was dominant in all sampled areas. The OC/EC ratio in PM2.5 ranged from 3.20 to 3.38. It can be concluded that the main sources of PM2.5 are emissions from gasoline and LPG exhaust, which come from vehicle and industrial combustion. Moreover, this study can provide supporting information for effective management and control of air pollution in urban areas. [ABSTRACT FROM AUTHOR]

Airports are significant contributors of atmospheric pollutant aerosols, namely ultrafine particles (UFPs). This study characterizes the particle number concentration (PNC), the median particle size (dmn50), and the metallic composition of medium-haul area and engine aerosols at two French airports (Paris-CDG and Marseille). This study followed the standard operating procedures for characterizing aerosol emissions from 5 nm to 8 μm (OECD, 2015; EN 17058:2018). It allows determining which are the specific parameters directly related to the emission sources and their contribution to the overall aerosols measured at workplace in airports. The particulate emissions observed during aircraft engine start-up were ~19× higher than the average airborne concentration. The particle size distributions remained mostly <250 nm with dmn50 < 100 nm (showing a specificity for the medium-haul area with an average dmn50 of ~12 nm). The dmn50 can be used to distinguish emission peaks due to aircrafts (dmn50~15 nm) from those due to apron vehicle activities (dmn50 > 20 nm). Chemical elements (titanium and zinc) were identified as potential tracers of aircraft emissions and occurred mainly at the micrometric scale. For aircraft engine emissions, UFPs are mainly due to fuel combustion with the presence of carbon/oxygen. The study concludes with suggestions for future research to extend on the findings presented. [ABSTRACT FROM AUTHOR]

In order to study the influence of air pollutant reduction measures on aerosol water-soluble ions, and organic carbon(OC)and element carbon(EC)during the 14th National Games in Xi'an city of Shaanxi, China, real-time observation instruments were used to motor the hourly concentration of the atmospheric pollutants(PM2.5, PM10, SO2, NO2, O3 and CO), meteorological elements, and chemical composition(OC, EC and water-soluble ions)of PM2.5 from August 6 to October 1, 2021. The results show that the air pollutant reduction measures have different effects on the diurnal variations of concentrations of O3 and PM2.5, mainly caused by the influence of temperature on photochemical processes and differences in diffusion conditions. The peak concentration of O3 on sunny days during the implementation of air pollutant reduction measures is higher, last longer, and the concentration changes more rapidly. The peak concentration of PM2.5 is higher in the daytime of the sunny days before the implementation of air pollutant reduction measures, while the peak concentration is higher at night of sunny days during the implementation of air pollutant reduction measures. The air pollutant reduction measures have different effects on the chemical components in PM2.5, especially the composition of OC. On sunny days during the implementation of air pollutant reduction measures, the concentrations of NO-3, SO2-4, NH+4, Cl-, Ca2+, Na+ and NO-2 decrease by 17.9%-71.8%, and the concentrations of K+, Mg2+ and EC increase by 1.9%-13.6%, the concentration of OC on sunny days only decreases by 1.0%, but the primary organic carbon(POC)increases by 13.6%, and the secondary organic carbon(SOC)decreases by 4.7%. The NO-3/SO2-4 ratio on sunny days during the implementation of air pollutant reduction measures(0.53)is much lower than that on sunny days before the implementation of air pollutant reduction measures(1.66), indicating that the contribution of traffic source emission is significantly reduced during the implementation of air pollutant reduction measures. Rainfall has a weak scavenging effect on NO-3 and NH+4, and increases their concentrations, but it has a strong scavenging effect on K+, Mg2+, Ca2+ and Na+. NO-3, SO2-4 and NH+4 are the essential components of water-soluble ions, accounting for 90.8% of the water-soluble ions(sunny days before the implementation of air pollutant reduction measures)to 95.8%(rainy days during the implementation of air pollutant reduction measures). The diurnal variations of water-soluble ions and carbonaceous aerosols differ at different stages.The diurnal variations of NO-3, SO2-4 and NH+4 present unimodal distributions on sunny days and multimodal distributions on rainy days. [ABSTRACT FROM AUTHOR]

The results of a back-trajectory analysis of 9-year (2013–2021) measurements of organic (OC) and elemental (EC) aerosol carbon concentrations made at the atmospheric monitoring station near St. Petersburg (Peterhof, 59.88° N, 29.83° E) are presented. The spatial location of sources was estimated by the concentration weighted trajectory (CWT) method in the geographic area 16°–44° E × 48°–68° N. The data allow us to identify the territories with the strongest OC and EC emissions and estimate the seasonal variability of these emissions. In particular, the estimates show that the most intense sources of OC and elemental aerosol carbon in the studied region are located in the Volga-Oka interfluve and on the adjacent territories. It is demonstrated that linear regression coefficients between CWT function values for OC and EC differ for different regions and seasons and may indicate the prevailing type of sources of carbon-containing aerosol particles. [ABSTRACT FROM AUTHOR]

The present study shows seasonal trends and potential sources of carbonaceous contents in PM10, i.e., organic carbon (OC), elemental carbon (EC), total carbonaceous aerosols (TCA), and secondary organic carbon (SOC) at central Delhi during January-December 2019. The annual mass abundance of PM10 exhibited large seasonal variability and varied from 42.0 to 397.2 µg/m3 (Average 182.4 ± 17.2 µg/m3). The highest mass abundance of PM10 was observed during winter (260.5 ± 24.7 µg/m3), followed by summer (200.4 ± 28.4 µg/m3), post-monsoon (190.0 ± 36.5 µg/m3), and monsoon (78.1 ± 13.7 µg/m3). Annual average mass concentrations of OC and EC were observed as 24.1 ± 2.7 and 7.9 ± 0.9 µg/m3, respectively, and their seasonal averages followed a similar trend as winter > post-monsoon > summer > monsoon. OC/EC ratio varied from 2.0 to 8.7 (Average 3.5), suggesting a wide range of contributions throughout the year arising from vehicular exhausts, wood-fuel burning, biomass burning, coal combustion, waste burning, and secondary organic aerosols. The annual average contribution of TCA to PM10 was ~ 26%, whereas the seasonal contribution was found to be the highest during winter (31%) and post-monsoon (30%) followed by, summer (28%), and monsoon (17%) respectively. The estimated concentrations of SOC were the highest during winter (12.9 ± 3.7 µg/m3), followed by post-monsoon (9.2 ± 4.6 µg/m3), summer (7.0 ± 1.7 µg/m3), and monsoon (2.3 ± 0.8 µg/m3) seasons. The highest contribution during winter and post-monsoon suggests the active role of boundary layer dynamics resulting in secondary particle formation. The study of carbon sub-fractions, along with PCA, revealed that EC1 and OC3 were the dominating fractions suggesting gasoline vehicular exhaust as the significant emission source. [ABSTRACT FROM AUTHOR]

This study examined the influence of fireworks on atmospheric aerosols over the Southern Indian city of Hyderabad during festival of Diwali using mass closure, stable carbon isotopes and the EPA-PMF model. Identification of chemical species in day and night time aerosol samples for 2019 and 2020 Diwali weeks showed increased concentrations of NH4+, NO3−, SO42−, K+, organic carbon (OC), Ba, Pb and Li, which were considered as tracers for fireworks. PM10 source apportionment was done using inorganic (trace elements, major ions) and carbonaceous (organic and elemental carbon; OC & EC) constituents, along with stable isotopic compositions of TC and EC. K+/Na+ ∼1 and K+nss/OC > 0.5 indicated contribution from fireworks. High NO3−, NH4+, Na+, Cl− and SO42− suggested the presence of deliquescent salts NaCl, NH4NO3 and (NH4)2SO4. TAE/TCE >1 suggested H+ exclusion, indicating possible presence of H2SO4 and NH4HSO4 in the aerosols. Ba, Pb, Sb, Sr and Fe increased by 305 (87), 12 (11), 12 (3), 3 (2) and 3 (4) times on Diwali nights, compared to pre-Diwali of 2019 (2020), and are considered as metallic tracers of fireworks. δ13CTC and δ13CEC in aerosols closely resembled that of diesel and C3 plant burning emissions, with meagre contribution from firecrackers during Diwali period. The δ13CEC was relatively depleted than δ13CTC and δ13COC. For both years, δ13COC-EC (δ13COC - δ13CEC) were positive, suggesting photochemical aging of aerosols during long-range transport, while for pre-Diwali 2019 and post-Diwali 2020, δ13COC-EC were negative with high OC/EC ratio, implying secondary organic aerosols formation. High toluene during Diwali week contributed to fresh SOA formation, which reacted with precursor 12C, leading to 13C depletions. Eight-factored EPA-PMF source apportionment indicated highest contribution from residue/waste burning, followed by marine/dust soil and fireworks, while least was contributed from solid fuel/coal combustion.

Low-cost, long-term measures of air pollution concentrations are often needed for epidemiological studies and policy analyses of household air pollution. The Washington passive sampler (WPS), an ultra-low-cost method for measuring the long-term average levels of light-absorbing carbon (LAC) air pollution, uses digital images to measure the changes in the reflectance of a passively exposed paper filter. A prior publication on WPS reported high precision and reproducibility. Here, we deployed three methods to each of 10 households in Ulaanbaatar, Mongolia: one PurpleAir for PM2.5; two ultrasonic personal aerosol samplers (UPAS) with quartz filters for the thermal-optical analysis of elemental carbon (EC); and two WPS for LAC. We compared multiple rounds of 4-week-average measurements. The analyses calibrating the LAC to the elemental carbon measurement suggest that 1 µg of EC/m3 corresponds to 62 PI/month (R2 = 0.83). The EC-LAC calibration curve indicates an accuracy (root-mean-square error) of 3.1 µg of EC/m3, or ~21% of the average elemental carbon concentration. The RMSE values observed here for the WPS are comparable to the reported accuracy levels for other methods, including reference methods. Based on the precision and accuracy results shown here, as well as the increased simplicity of deployment, the WPS may merit further consideration for studying air quality in homes that use solid fuels. [ABSTRACT FROM AUTHOR]

To identify the characteristics and sources of carbonaceous aerosols in an urban area (UA) and rural area (Guihua Township, GH) of Nanchong City, organic carbon (OC) and elemental carbon (EC) were measured in fine particulate matter (PM2.5) samples collected from December 2014 to April 2016. The results showed that the average concentrations of PM2.5, OC, EC, and secondary organic carbon (SOC) in UA were 66.23±3.68 μg/m³, 13.34±0.93 μg/m³, 3.80±0.29 μg/m³ and 10.05±0.83 μg/m³, respectively, and those in GH were 60.13±4.28 μg/m³, 13.82±1.03 μg/m³, 3.92±0.44 μg/m³ and 10.23±0.90 μg/m³, respectively. The seasonal variations in PM2.5, OC, EC, and SOC in UA and GH were similar, with the order summer < spring < autumn < winter. The average OC/EC ratio in UA was 4.72±0.31, and that in GH was 5.14±0.38. In addition, K+, Pb, Zn, and As were positively correlated with OC and EC. This result indicated that biomass burning, fossil combustion, and motor vehicle exhaust within the Sichuan Basin were the main sources of PM2.5 in Nanchong City. The poor meteorological diffusion conditions prevalent for pollutants were the main reason for the high concentration of carbonaceous aerosols in Nanchong City. [ABSTRACT FROM AUTHOR]

Filtering facepieces (FFP), mainly class FFP2 particle half masks (EN 149:2001#x02009;+ A1:2009), are commonly used in European mines to protect workers from respirable dust, especially from particulate matter (PM) with a diameter of 4 µm or less (PM4). The aerosol associated with diesel exhaust (DE) is dominated by submicrometer particles (with a diameter of less than 1 µm) and nanoparticles (size in the range between 10 and 500 nm). In the European Union (EU), the occupational exposure level (OEL) for DE has been defined in terms of elemental carbon (EC) concentration. Based on measurements in underground mines, on average, 60% of EC associated with PM4 was contained in PM with a diameter of 1 µm or less (PM1). Particle number size distribution (PNSD) of PM1 showed that the most numerous were particles in the size range of 20 to 300 nm. Four popular types of certified FFP2 half masks were tested for penetration. Brand new and thermally conditioned masks of each type were included in the study. NaCl aerosol in the particle size range of 7 to 270 nm was used for tests. Filtration efficiencies of 98.5% (median) or higher were achieved. Aerosol penetration was a function of particle size. Maximum penetration was observed between 20 and 60 nm, depending on the type of mask. During filtration, aerosol characteristics changed. Nanoparticles ranging in size from 7 to about 60 nm were removed to a very limited extent. The change was more noticeable for brand-new masks compared to the thermally conditioned ones. Usually, aerosol penetration through thermally conditioned masks was lower and more consistent. It was confirmed that the half masks of the FFP2 class are capable of filtering submicrometer aerosol in particle size range 7 to 270 nm with an efficiency exceeding 96% and can contribute to achieving compliance with the OEL for DE in the mining sector. [ABSTRACT FROM AUTHOR]

Carbonaceous aerosols (CAs), including elemental carbon (EC) and organic carbon (OC), have become the dominant component in PM2.5 in many Chinese cities, and it is imperative to address their spatiotemporal variations and sources in order to continually improve air quality. In this study, the mass concentrations and light absorption properties of EC and OC in PM2.5 were investigated at diverse sites in Guangzhou, in the winter of 2020 and the autumn of 2021, using the DRI Model 2015 thermal–optical carbon analyzer. The results showed that total EC and organic matter (OM = OC × 1.8) could account for nearly 30% of the PM2.5 mass concentrations. Secondary production was the most important source for OC, with secondary OC (SOC) percentages in the OC as high as 72.8 ± 7.0% in autumn and 68.4 ± 13.1% in winter. Compared to those in 2015, OC and EC concentrations were reduced by 25.4% and 73.4% in 2021, highlighting the effectiveness of control measures in recent years. The absorption coefficient of brown carbon at 405 nm (babs,BrC,405) decreased by over 40%, and the mass absorption coefficient (MAC) at 405 nm of total carbon (TC) decreased by over 30%. EC and OC concentrations and the light absorption of black carbon (babs,BC,405) showed no significant diurnal differences in both autumn and winter mainly because the reduction in anthropogenic emissions at night was compensated by the lowering of the boundary layer. Differentially, babs,BrC,405 was significantly lower during daytime than at night in autumn, probably due to the daytime photobleaching effect. The sources of EC, OC, BC, and BrC were preliminarily diagnosed by their correlation with typical source markers. In autumn, babs,BrC,405 might be related to biomass burning and coal combustion, while babs,BC,405 were largely related to vehicle emissions and coal combustion. In winter, babs,BrC,405 was closely related to coal combustion. [ABSTRACT FROM AUTHOR]

This paper investigates the chemical composition of Particulate Matter, Organic Carbon (OC), and Elemental Carbon (EC) in residential and traffic sites in Mumbai. The average PM2.5 and PM10 concentrations at the traffic site (Sakinaka) were 240 µg/m3 and 424 µg/m3, respectively. The observed levels of OC were 35 µg/m3, 22 µg/m3, and 15.5 µg/m3 at Sakinaka junction (high-density traffic), YP-Gate (low-density traffic), and Hostel Premise (Residential), respectively. The average OC/EC ratio value was high (4.5) at the residential site, indicating contributions from stationary combustion sources and secondary production of carbonaceous species to OC. The residential site has a higher percentage of low volatile OC fraction (57%) in total OC than the traffic sites. On the other hand, Sakinaka has a higher percentage of highly volatile OC fractions (36%) in total OC. The crustal-originated metals were dominating in all areas, but the concentration of metals from anthropogenic sources was highest at Sakinaka, i.e., As (381 ng/m3), Pb (352 ng/m3), Zn (679 ng/m3). The K/Al, Ca/Al, Mg/Al, and Fe/Al ratios were high in all the samples compared to the crustal ratio indicating biomass burning and traffic emission sources of these metals. PM originating from traffic was more enriched with heavy metals that are toxic to human health, increasing cancer risks (CR) through inhalation. The hazard quotient was above 1 at all the locations, and CR was above 1 × 10− 4, causing health risks. According to the dosimetry model, more PM was deposited in the lungs of traffic location occupants through inhalation, increasing the cancerous risk. [ABSTRACT FROM AUTHOR]

Background This paper presents and discusses the results of the determination of elemental carbon emitted in diesel engine exhaust into the air of workplaces where machines and equipment with diesel engines are used. In order to assess occupational exposure to elemental carbon (EC) as a marker of exhaust gases emitted by diesel engines, 51 ground-based workplaces where people who operate or maintain equipment with this type of engine work were measured. Measurements were also carried out at 9 workplaces in non-coal mines. Material and Methods For air sampling at workplaces of diesel exhaust emitting machines and equipment located on the surface, a cartridge sampler without an impactor with a quartz filter was used for elemental carbon determination, while for measurements in non-coal mines the Higgins-Dewell Cyclone FH022 respirable fraction sampler was used. The thermo-optical carbon analysis method using a flame ionisation detector was used to determine elemental carbon. Results Analysis of the results of the determined elemental carbon concentrations at workplaces located on the ground, i.e., in car repair shops, and in the steelworks where combustion forklifts are operated, showed that the highest concentrations of elemental carbon were determined at the old forklift workplaces in the steelworks. The determined EC concentrations at these workstations were 353 μg/m 3 and 78 μg/m 3 , respectively. In the non-coal mines, elemental carbon concentrations were in the range of 7.5–50 μg/m 3 . Conclusions Exposure assessment at the surveyed workplace in the steelworks showed the highest 7-fold exceedance of the maximum admissible concentration (MAC) at the position of the combustion forklift operator. At the other surveyed workplaces in the car repair shop the marked concentrations were in the range of 0.1–0.5 MAC or

To evaluate carbonaceous components in the ambient air in the eastern region of Indonesia, 35 Total Suspended Particulate Matter (TSP) samples were collected on four characteristic roadsides on Sultan Alauddin Street, in Makassar City, using a high-volume air sampler. The average TSP concentration was 279.7 μg/m3, which exceeded both the National Ambient Air Quality Standard (NAAQS) of Indonesia and the World Health Organization (WHO) standards. The highest concentration reached 838.6 μg/m3 in the GR (gravel) site, which had the highest number of vehicles and was near a U-turn. TSP concentration was higher during peak hours (morning and late afternoon) than off-peak hours (noon). The main component of the total carbon (TC) fraction was organic carbon (OC), which showed a strong correlation with elemental carbon (EC) (r values for the morning, noon, and late afternoon were 0.89, 0.87, and 0.97, respectively), indicating that the carbon components were derived from common sources. TSP had a strong correlation with carbon components, except for char-EC. OC vs. soot-EC and EC vs. soot-EC also correlated well, suggesting the dominant influence of vehicle exhaust emissions. Non-exhaust emissions had a slight influence during peak hours, particularly at the GR site.

More than a yearlong investigation (2008-2009) was carried in Srinagar, in the North-Western folds of Himalayas, involving the estimation of Total Suspended Particulate Matter (TSPM) and different carbonaceous fractions associated with it namely, Total carbon (TC), Elemental carbon (EC), Black Carbon (BC) Organic carbon (OC), no such direct estimates were available at that time for the valley and neither have they been updated till date. The samples collected on quartz filter using high volume sampler in a time series sequence and analyzed reflected marked seasonal dependence. The variability observed in carbonaceous contents of ambient aerosols was found to be similar as generally observed from other urban areas, however the relief along with prevalent meteorology was found to have a profound impact on the concentration of TSPM as well its constituent carbonaceous fractions. The higher values of TSPM were observed during summer months and the contribution of OC to TC as well. The contribution of EC to Tc was higher during colder months, EC arising from combustion sources attributed largely to petrogenic sources (fossil fuel) could be distinctly seen to be augmented by the biomass burning during autumn and winter; also increase in the OC content mainly starting in spring and continuing through to summer can be to attributed to active biogenic sources. [ABSTRACT FROM AUTHOR]

The carbonaceous particles represent a significant fraction in the particulate matter (PM) and are considered an environmental hazard due to their effects on climate and health. The main goal in this research is to identify and analyze the scope that have been achieved so far on the characterization and measurement of the carbonaceous fraction present in PM, a great contribution to global pollution and thus to the deterioration of public health. The ProKnow-C methodology was used to build a bibliographic portfolio and perform a bibliometric and systemic analysis of the information found in the chosen databases. The contribution of these carbonaceous compounds to PM is very significant, reaching values up to 50%. The most used methods for the determination of organic and elemental carbon are thermo-optical reflectance and transmittance. Positive Factorization models are used worldwide to determine potential sources of particulate matter emissions. Even though various studies have been developed to understand these carbonaceous substances, there are several limitations in the measurements and limited knowledge on the subject. The positive outcomes and future possibilities were analyzed as well. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Nanchang University (Engineering & Technology) is the property of Nanchang University and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Aerosols are a significant source of dissolved black carbon (DBC) in the ocean. However, how anthropogenic activities, including fossil fuel (FF) burning and human‐initiated biomass burning (BB), would affect the seasonal variations in the concentration and condensation degree of aerosol DBC was not well constrained. To fill this knowledge gap, we collected 33 aerosol samples from December 2018 to September 2019 at a southeast coastal site in China. Concentrations of DBC, water‐soluble organic carbon (WSOC), and elemental carbon (EC) were determined, and air quality data were collected. DBC concentration was 0.02–0.23 μgC m−3, with significantly higher values in spring and winter, and was affected by sources, rainfall frequency, and secondary processes. The source of DBC, as indicated by DBC/WSOC (range: 0.009–0.045) and DBC/EC (range: 0.007–0.065), was dominated by FF burning. Furthermore, the significantly higher DBC/WSOC value in late April to July indicated enhanced contribution from BB that was mainly associated with airmass transported from Southeast Asia (SEA). We further estimated that ∼30% of aerosol DBC was from BB from May to July. The condensation degree of DBC was variable, with significantly higher values in winter and spring, which might be associated with prolonged photo‐dissolution. Significant correlations were also observed between DBC and PM10 and PM2.5, which might be utilized to estimate DBC deposition flux, albeit requiring more studies. Our study emphasized the influence of human activities (including BB activities) on atmospheric DBC deposition, which might affect the regional and even global DBC pools. Plain Language Summary: As a significant source of dissolved black carbon (DBC) to the ocean, the sources and temporal variation in its concentration and condensation degree were not well constrained. In this study, we collected 33 aerosol samples at a coastal site in China. We determined concentrations of DBC, water‐soluble organic carbon, and elemental carbon (EC). Air quality and meteorological parameters were also collected. Our results showed that DBC at this coastal site was primarily derived from fossil fuel (FF) burning, with enhanced contribution from biomass burning that was brought by East Asian Monsoon. In addition, DBC concentration varied significantly among seasons, and was influenced by changes in sources, rainfall frequency as well as secondary processes. Moreover, we found that DBC concentration was significantly positively correlated with PM10 and PM2.5, which provided a potential way to predict DBC depositional flux in other regions that was mainly affected by FF burning. Our study indicated that human activities (FF burning and human‐initiated biomass burning) could have significant impact on atmospheric DBC deposition, which might also affect the oceanic DBC pool in the future. Key Points: The seasonal variation in the dissolved black carbon (DBC) concentration was affected by sources, rainfall frequency, and secondary processes in XiamenThe sources of DBC in the aerosols mainly originated from the burning of fossil fuelThe DBC concentration was highly significantly correlated with PM10 and PM2.5, which could be a simple way to estimate DBC deposition flux [ABSTRACT FROM AUTHOR]

Copyright of Environmental Science & Technology (10036504) is the property of Editorial Board of Environmental Science & Technology and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Diesel engine exhaust (DE) consists of a complex mixture of gases and aerosols, originating from sources such as engines, turbines, and power generators. It is composed of a wide range of toxic compounds ranging from constituents that are irritating to those that are carcinogenic. The purposes of this work were to characterize DE originating from different engine types on a ship operating offshore and to quantify the potential exposure of workers on the ship's helicopter deck to select DE compounds. Sampling was conducted on a Norwegian Nansen-class frigate that included helicopter operations. Frigate engines and generators were fueled by marine diesel oil, while the helicopter engine was fueled by high flash point kerosene-type aviation fuel. Exhaust samples were collected directly from the stack of the diesel engine and one of the diesel generator exhaust stacks, inside a gas turbine exhaust stack, and at the exhaust outlet of the helicopter. To characterize the different exhaust sources, non-targeted screening of volatile and semi-volatile organic compounds was performed for multiple chemical classes. Some of the compounds detected at the sources are known irritants, such as phthalic anhydride, 2,5-dyphenyl-p-benzoquinone, styrene, cinnoline, and phenyl maleic anhydride. The exhaust from the diesel engine and diesel generator was found to contain the highest amounts of particulate matter and gaseous compounds, while the gas turbine had the lowest emissions. Personal exposure samples were collected outdoors in the breathing zone of a helicopter deck operator over nine working shifts, simultaneously with stationary measurements on the helicopter deck. Elemental carbon, nitrogen dioxide, and several volatile organic compounds are known to be present in DE, such as formaldehyde, acrolein, and phenol were specifically targeted. Measured DE exposures of the crew on the helicopter deck were variable, but less than the current European occupational exposure limits for all compounds, except elemental carbon, in which concentration varied between 0.5 and 37 µg/m3 over nine work shifts. These findings are among the first published for this type of working environment. [ABSTRACT FROM AUTHOR]

To characterize seasonal carbonaceous aerosol pollution in Taiyuan, a typical city in North China that mainly relies heavily on coal, a total of 124 PM2.5 samples were collected from August 2018 to the next May. The annual mean PM2.5 concentration was 83.8 ± 48.5 μg m−3, with a seasonal rank of winter (117.4 ± 47.6 μg m−3) > spring (79.2 ± 34.3 μg m−3) > fall (67.3 ± 34.7 μg m−3) > summer (31.8 ± 6.5 μg m−3), suggesting that fine particulate pollution was still serious in cold seasons. Organic carbon (OC) and elemental carbon (EC) showed similar seasonal patterns with PM2.5. The mean concentration values of OC in summer, fall, winter, and spring were 5.1 ± 0.9, 11.8 ± 6.4, 22.1 ± 14.9, and 12.2 ± 6.7 μg m−3, respectively. The mean concentration values of EC in summer, fall, winter, and spring were 1.5 ± 0.3, 2.5 ± 1.6, 4.4 ± 2.8, and 2.4 ± 1.5 μg m−3, respectively. The proportion of total carbon aerosol (TCA) was about 31.7%, 33.8%, 30.0%, and 27.0% in PM2.5 in summer, fall, winter, and spring, respectively. The good correlation between OC vs. EC and the high value of OC/EC suggests that coal and biomass combustion were the main emissions in cold seasons, aggravated by adverse meteorological conditions and the dustpan-shaped terrain. The mean annual secondary organic carbon (SOC) concentration was 6.1 ± 7.1μg m−3, representing 38.7% of the OC content. The present results presented the serious carbonaceous particulate pollution, which might affect haze pollution in cold seasons. [ABSTRACT FROM AUTHOR]

In this study, we developed a practical approach to augment elemental carbon (EC) emissions to improve the reproducibility of the most recent air quality with photochemical grid modeling in support of source-receptor relationship analysis. We demonstrated the usefulness of this approach with a series of simulations for EC concentrations over Northeast Asia during the 2016 Korea-United States Air Quality study. Considering the difficulty of acquiring EC observational data in foreign countries, our approach takes two steps: (1) augmenting upwind EC emissions based on simulated upwind contributions and observational data at a downwind EC monitor considered as the most representative monitor for upwind influences and (2) adjusting downwind EC emissions based on simulated downwind contributions, including the effects of updated upwind emissions from the first step and observational data at the downwind EC monitors. The emission adjustment approach resulted in EC emissions 2.5 times higher than the original emissions in the modeling domain. The EC concentration in the downwind area was observed to be 1.0 μg m−3 during the study period, while the simulated EC concentration was 0.5 μg m−3 before the emission adjustment. After the adjustment, the normalized mean error of the daily mean EC concentration decreased from 48 % to 22 % at ground monitor locations. We found that the EC simulation results were improved at high altitudes, and the contribution of the upwind areas was greater than that of the downwind areas for EC concentrations downwind with or without emission adjustment. This implies that collaborating with upwind regions is essential to alleviate high EC concentrations in downwind areas. The developed emission adjustment approach can be used for any upwind or downwind area when transboundary air pollution mitigation is needed because it provides better reproducibility of the most recent air quality through modeling with improved emission data.

A cascade impactor type sampler equipped with an inertial filter was used to collect size-segregated particles down to ultrafine particles (UFPs or PM0.1) on Batam Island in Sumatra, Indonesia, bordered by Singapore and Malaysia during a wet and the COVID-19 pandemic season in 2021. Carbonaceous species, including organic carbon (OC) and elemental carbon (EC), were analyzed by a thermal/optical carbon analyzer to determine the carbon species and their indices. The average UFP was 3.1 ± 0.9 μg/m3, which was 2–4 times lower than in other cities in Sumatra during the same season in the normal condition. The PMs mass concentration was largely affected by local emissions but long-range transportation of particles from Singapore and Malaysia was also not negligible. The air mass arrived at the sampling site passed the ocean, which introduced out clean air with a low level of PMs. The backward trajectory of the air mass and the largest fraction of OC2 and OC3 in all sizes was identified as being transported from the 2 above countries. OC is the dominant fraction in TC and the ratio of carbonaceous components indicated that origin of all particle sizes was predominantly vehicle emissions. UFPs were dominantly emitted from vehicles exhaust emission, while coarser particles (>10 μm) were influenced by the non-exhaust emissions, such as tire wear. Other particles (0.5–1.0; 1.0–2.5; and 2.5–10 μm) were slightly affected by biomass burning. The effective carbon ratio (ECR) and inhalation dose (ID) related EC indicated that finer particles or UFPs and PM0.5-1 contributed more to human health and global warming.

Advanced carbon materials have played an important function in the field of energy conversion and storage. The green and low-carbon synthesis of elemental carbon with controllable morphology and microstructure is the main problem for carbon materials. Herein, we develop a green and low-carbon method to synthesize porous carbon by reacting CO2 with LiAlH4 at low temperatures. The starting reaction temperatures are as low as 142, 121, and 104 °C for LiAlH4 reacting with 1, 30, and 60 bar CO2, respectively. For the elemental carbon, the porosity of elemental carbon gradually decreased, whereas its graphitization degree increased as the CO2 pressure increased from 1 bar to 60 bar. CO2 serves as one of the two reactants and the CO2 pressure can adjust the thermodynamic and kinetic properties of the formation reaction for synthesizing elemental carbon. The mechanism for CO2 pressure-dependent microstructure and morphology of carbon is discussed on the basis of the formation reaction of elemental carbon and gas blowing effect of H2 and CO2. The elemental carbon with different morphology and microstructure exhibits distinct electrochemical lithium storage performance including reversible capacity, rate capability, cycling stability, and Coulombic efficiency, owing to their different lithium storage mechanism. The elemental carbon synthesized at 30 bar CO2 delivers the highest reversible capacity of 506 mAh g−1 after 1000 cycles even at 1.0 A g−1. Advanced energy storage technology based on the green and low-carbon synthesis of carbon materials is a requisite for providing a stable and sustainable energy supply to meet the ever-growing demand for energy. [ABSTRACT FROM AUTHOR]

The mass and light absorption contributions of organic carbon (OC), elemental carbon (EC), and mineral dust influence glacial melting and potentially contribute to climate change over the high Himalayas and Tibetan Plateau (HTP). Plateau-scale investigations of these components and their respective light absorption are limited due to the high altitude. In this study, we combined the analysis of major light-absorbing substances and their corresponding multiwavelength absorption to determine their specific contributions firstly. We investigated the spatial variations of total suspended particle (TSP) mass across the HTP, noting high contributions from dust, carbonaceous components, and secondary inorganic aerosols (SNA, including sulfate, nitrate, and ammonium). Enhanced levels of primary and secondary OC and SNA were observed in the marginal areas of the HTP, associated with high relative humidity (RH) and OX levels (O 3 +NO 2). EC was the primary contributor to light absorption, accounting for approximately 68%, 46%, and 64% in Ngari, Qinghai Lake, and Beiluhe, respectively. We found higher light-absorbing contributions from carbonaceous aerosols in the marginal areas compared to the central HTP site, particularly during the heating seasons (∼90%). Fugitive dust significantly contributed to TSP mass but not to light absorption. The concurrent constraints on the mass and optical properties of OC, EC, and dust in this study can help reduce uncertainties in climate models specific to the HTP. [Display omitted] • The dominant light-absorbing was attributed to EC in the HTP. • Enhanced carbonaceous aerosol light-absorbing contributions were obtained in the HTP margin area. • Fugitive dust was an important contributor to aerosol mass, while not for light absorption. [ABSTRACT FROM AUTHOR]

Within the scope of this study, two equivalent PM 2.5 samplers were designed and developed to eliminate sampling artifacts in the results of atmospheric particulate organic carbon (OC) and particulate polycyclic aromatic hydrocarbons (PAH) caused by volatile organic compounds (VOCs) and gas phase PAH compounds, respectively. A mass loss of less than 10% due to the denuders was observed. Study results showed that if an impregnated denuder is not used, the results of atmospheric particle OC concentrations will be reported with higher values due to positive errors of 53.2 ± 7.23% (median: 52.00%) on average. It was observed that the total error (net error) was still positive, but decreased to an average of 35.1 ± 16.8% (median: 31.0%) after including the negative errors quantified from the backup filter into the calculation. In cases where denuders were not used in the sampling, it was observed that the results with positive errors of 41.0 ± 14.6% (median: 33.8%) on average would be obtained for the total PAHs. Ozone-induced negative interference was the highest in Acenapthylene (28%), followed by Fluoranthane (20%), Phenanthrene (18%), and 15% for Np and Benzo[g,h,i]perylene compounds, relative to their medians. Negative errors of 10% or less were found in all other individual PAH compounds. [Display omitted] • Particulate OCs have been reported in overestimated amounts as much as 53%. • Organic denuder and backup filters reduced VOC artifacts to 35.1%. • Ultrafine particulates were detected in the backup filter. • Measured OCs in the backup filters must be added to OCs in the primary filter. • OC loss from the primary filter increased as the ambient temperature increases. [ABSTRACT FROM AUTHOR]

Low-cost, long-term measures of air pollution concentrations are often needed for epidemiological studies and policy analyses of household air pollution. The Washington passive sampler (WPS), an ultra-low-cost method for measuring the long-term average levels of light-absorbing carbon (LAC) air pollution, uses digital images to measure the changes in the reflectance of a passively exposed paper filter. A prior publication on WPS reported high precision and reproducibility. Here, we deployed three methods to each of 10 households in Ulaanbaatar, Mongolia: one PurpleAir for PM2.5; two ultrasonic personal aerosol samplers (UPAS) with quartz filters for the thermal-optical analysis of elemental carbon (EC); and two WPS for LAC. We compared multiple rounds of 4-week-average measurements. The analyses calibrating the LAC to the elemental carbon measurement suggest that 1 µg of EC/m3 corresponds to 62 PI/month (R2 = 0.83). The EC-LAC calibration curve indicates an accuracy (root-mean-square error) of 3.1 µg of EC/m3, or ~21% of the average elemental carbon concentration. The RMSE values observed here for the WPS are comparable to the reported accuracy levels for other methods, including reference methods. Based on the precision and accuracy results shown here, as well as the increased simplicity of deployment, the WPS may merit further consideration for studying air quality in homes that use solid fuels.

Carbonaceous aerosols (CAs), including elemental carbon (EC) and organic carbon (OC), have become the dominant component in PM2.5 in many Chinese cities, and it is imperative to address their spatiotemporal variations and sources in order to continually improve air quality. In this study, the mass concentrations and light absorption properties of EC and OC in PM2.5 were investigated at diverse sites in Guangzhou, in the winter of 2020 and the autumn of 2021, using the DRI Model 2015 thermal–optical carbon analyzer. The results showed that total EC and organic matter (OM = OC × 1.8) could account for nearly 30% of the PM2.5 mass concentrations. Secondary production was the most important source for OC, with secondary OC (SOC) percentages in the OC as high as 72.8 ± 7.0% in autumn and 68.4 ± 13.1% in winter. Compared to those in 2015, OC and EC concentrations were reduced by 25.4% and 73.4% in 2021, highlighting the effectiveness of control measures in recent years. The absorption coefficient of brown carbon at 405 nm (babs,BrC,405) decreased by over 40%, and the mass absorption coefficient (MAC) at 405 nm of total carbon (TC) decreased by over 30%. EC and OC concentrations and the light absorption of black carbon (babs,BC,405) showed no significant diurnal differences in both autumn and winter mainly because the reduction in anthropogenic emissions at night was compensated by the lowering of the boundary layer. Differentially, babs,BrC,405 was significantly lower during daytime than at night in autumn, probably due to the daytime photobleaching effect. The sources of EC, OC, BC, and BrC were preliminarily diagnosed by their correlation with typical source markers. In autumn, babs,BrC,405 might be related to biomass burning and coal combustion, while babs,BC,405 were largely related to vehicle emissions and coal combustion. In winter, babs,BrC,405 was closely related to coal combustion.

The most common commercial oils in the Chinese market are two petrol types with octane levels of 93 and 97. To determine the source spectrum of air pollutant emissions, we herein investigated the specific emission sizes of the total suspended particles (TSP), total carbon (TC), elemental carbon (EC), organic carbon (OC), and polycyclic aromatic hydrocarbons (PAHs) from a petrol engine fueled with 93# and 97# petrol in 2016 (based on Chinese national IV gasoline standard). We found that while 93# emitted a higher TSP content, 97# emitted greater TC, EC, OC, and PAHs. The highest carbon contents were found in the < 0.25 µm and 0.44–1.0 µm size fractions for the 93# and 97# petrol, respectively. OC content showed a significant positive correlation with EC, and EC2 (at 740 ℃) was the main carbon fragment in both petrol exhausts. The highest PAH content occurred in the 0.25–0.44 µm size-bin, differing from the results for TC, EC, and OC, and medium molecular weight (4 rings) PAHs were the primary component in the emissions. These results indicate that fuel composition and octane sensitivity have a prominent effect on the size distributions of TC (including EC, OC, and PAHs). Thus, more studies on the carbon content at specific emission sizes in petrol exhaust should be conducted to clarify the main factors impacting these variations. [ABSTRACT FROM AUTHOR]

The study on the light absorption of carbonaceous components is a research hotspot in the field of aerosol optical. Size distribution and lensing effect have great influence on the absorption of elemental carbon (EC) and brown carbon (BrC). However, few studies were conducted on the spatial variations of BC and BrC absorption with different size ranges in different regions. In this study, the mass concentration, absorption coefficient and mass absorption efficiency (MAE) of size-resolved carbonaceous components in three functional areas of Nanjing were compared based on offline sampling and experimental analysis. Bimodal and unimodal size distributions were found for EC and BrC mass concentrations at the three sites, respectively. Affected by the emission of diesel vehicles and aggregation condensation, high EC concentration in the size range of 0.56–1 μm was found at the suburban site. Due to the secondary formation from VOCs, high BrC concentration in the size range of 0.18–0.32 μm was observed at the industrial site. High EC concentration in the size range of 0.18–0.32 μm caused by diesel emission was the main reason for the high EC absorption in the regional area. Compared with vehicle emissions, the absorption capacity of secondary BrC was weaker. The variation of MAE values caused by various sources was the key factor leading to BrC absorption, which varied greatly in different regions. This study is helpful to understand the variation of light absorption of carbonaceous component and its source influence in a typical polluted city in the Yangtze River Delta, which provides important data support for the comprehensive evaluation of the role of aerosol light absorption in the change of radiative forcing in different regions. [ABSTRACT FROM AUTHOR]