Source Apportionment Of Black Carbon Research Articles

Characteristics and source apportionment of black carbon the urban and desert underlying surfaces

The spatial distribution of black carbon (BC) concentrations was highly variable across different underlying surfaces. Differences in meteorological conditions and emission sources led to great temporal and spatial variations in BC characteristics. As the most important absorbing aerosol, BC can affect radiation, clouds, and surface snow. BC mass concentrations were measured using a seven channel aethalometer (AE-33) in the Urumqi and Taklimakan Deserts from January to December 2022.The aethalometer data, potential source contribution function (PSCF), and concentration-weighted trajectory (CWT) models were used to analyse the variation characteristics, potential sources, and affected areas. Results showed that the BC concentrations in the Taklamakan Desert and Urumqi were in the range of 0–500 ng·m−3, accounting for 66.20 % and 59.50 % of the total, respectively. The backward trajectory simulation of BC mass concentration in the tower and Urumqi using the HYSPLIT model found that the airflow trajectories in the tower in summer corresponded to the BC concentration in the following order: trajectory 4 > trajectory 3 > trajectory 2 > trajectory 1, and trajectory 4 originated from the Turpan airflow accounting for 46.19 % of the total, which corresponded to the highest BC concentration of 621.73 ng·m−3. The trajectories of the airflow in Urumqi in summer corresponded to the BC concentration in the order of high to low, and the BC concentration in summer corresponded to the highest concentration in the Turpan airflow. BC concentrations arranged from high to low were trajectory 1 > trajectory 5 > trajectory 3 > trajectory 4 > trajectory 2. Trajectories 3, 4, and 5 airflow directions were the same, and the airflow trajectory accounted for 47.48 %, corresponding to BC concentrations of 599.82 ng·m−3, 579.99 ng·m−3, and 555.85 ng·m−3, respectively. Tower in the spring compared with other seasons of the CWT value of >400 ng·m−3 had the widest coverage, and Urumqi had more source areas contributing to moderate pollution concentration weights in winter (400 ng·m−3 < CWT < 800 ng·m−3). The conclusions of this study provide a scientific basis for regional environmental management and the formulation of air pollution measures in Xinjiang.

Source apportionment of black carbon using an advanced Aethalometer model in a typical industrial city of China

Black carbon (BC) aerosol can lead to adverse health effects and drive climate change; therefore, the characteristic research and identification of BC sources are essential for lowering emissions. In this study, equivalent black carbon (eBC) measurement was performed using a seven-wavelength Aethalometer (AE33) at an urban site in a typical industrial city (Zibo) of Northern China for the first time. The monitoring was performed from February 2021 to January 2022. The mass absorption cross-section (MAC) of AE33 was optimised using the online elemental carbon (EC) data, and eBC was corrected using the MAC. The corrected annual BC concentration was 1.72 ± 1.18 µg/m3. The diurnal variation of BC depicted a bimodal distribution. Furthermore, the BC concentration on weekends was 18 % lower than on weekdays. The diurnal variation and weekend effect reflect the critical contributions of traffic emission to BC concentration. The source apportionment of BC was calculated by a constraining Aethalometer model, which restricted the Ångström exponent using the online potassium ions. The results revealed that BC was not significantly affected by biomass burning (BCbb) in Zibo. The relative contribution of BCbb was higher in winter than in other seasons. The daily morning peak of BC was primarily influenced by traffic sources, whereas the contribution of biomass burning increased after 17:00 in the evening peak. Our findings suggest that it is more important to control fossil fuel sources for BC emission reduction in Zibo, while it is necessary to strengthen the control of biomass combustion sources in winter.

Light absorption properties and source contributions of black and brown carbon in Guangxi, southern China

Black carbon (BC) and brown carbon aerosols (BrC) are primary light-absorbing carbonaceous aerosols that significantly influence the global and regional radiation balance, as well as air quality. Guangxi Zhuang Autonomous Region, as a primarily agricultural province of China and neighbouring Southeast Asia, is subjected to both local emissions and pollution transport from Southeast Asian biomass burning. To investigate the light absorption properties and source contributions of BC and BrC in this region, observations from a 7-wavelength Aethalometer are employed to estimate the light absorption properties of BC and BrC over the period from March to December 2020 in Nanning, China. This study focuses on analysing the absorption contributions of BC and BrC to the total absorption of carbonaceous aerosols, identifying their emission sources, and exploring the impact of long-range transport of biomass burning (BB) from Southeast Asia on BC and BrC based on backward trajectory and weighted concentration-weighted trajectories (WCWT) model. Our results show that the absorption Ångström exponent (AAE) of light-absorbing carbonaceous aerosols varies from 0.54 to 2.08, reflecting the presence of different absorbing aerosol sources with specific optical properties. The average absorption coefficients of BC and BrC at 370 nm, denoted as babs,BC(370) and babs,BrC(370), are 42.25 Mm−1 and 9.63 Mm−1, respectively, with the highest value observed in winter. The average absorption of BrC contributes 19% to the total absorption from light-absorbing carbonaceous aerosols, and this contribution decreases for high babs,BrC(370) values, with the highest value in summer at 20%. For the BC source apportionment using a site-specific AAE, fossil fuel combustion (FF) contributes 57%, with its highest proportion in summer (62%). Meanwhile, biomass burning (BB) accounts for 43%, with the greatest contribution in winter (58%). These results highlight the considerable role of BB in Guangxi. In terms of the BrC sources, secondary BrC (BrCsec) is responsible for 32% of the total light absorption of BrC at 370 nm, and is particularly characterized by a much higher level of 35% at night, meaning the dominant role of BrCsec in Nanning. The relative contribution of babs,BrC,sec(370) increases with a higher contribution of babs,BrC(370) to aerosol absorption. Compared with the BrCsec, primary BrC values are higher in spring and winter, due to the increased emissions from biomass burning. Based on the analysis of backward trajectory and WCWT, the increase in BC and BrC during March and April is mainly influenced by the long-range transport of BB from Southeast Asian countries, e.g., Laos and Thailand. Overall, the contributions of BB and FF emissions to BC are comparable in Guangxi, while BrC mainly formed from primary sources is significantly impacted by both local emissions and the long-range transport of BB. Studying the optical characteristics and emission sources in this region can promote the understanding of the radiative effect of light-absorbing carbonaceous aerosols under the joint contributions from biomass burning and industrial emissions.

Local and NON-LOCAL source apportionment of black carbon and combustion generated PM2.5

Current methods for measuring black carbon aerosol (BC) by optical methods apportion BC to fossil fuel and wood combustion. However, these results are aggregated: local and non-local combustion sources are lumped together. The spatial apportioning of carbonaceous aerosol sources is challenging in remote or suburban areas because non-local sources may be significant. Air quality modeling would require highly accurate emission inventories and unbiased dispersion models to quantify such apportionment. We propose FUSTA (FUzzy SpatioTemporal Apportionment) methodology for analyzing aethalometer results for equivalent black carbon coming from fossil fuel (eBCff) and wood combustion (eBCwb).We applied this methodology to ambient measurements at three suburban sites around Santiago, Chile, in the winter season 2021. FUSTA results showed that local sources contributed ∼80% to eBCff and eBCwb in all sites. By using PM2.5 – eBCff and PM2.5 – eBCwb scatterplots for each fuzzy cluster (or source) found by FUSTA, the estimated lower edge lines showed distinctive slopes in each measurement site. These slopes were larger for non-local sources (aged aerosols) than for local ones (fresh emissions) and were used to apportion combustion PM2.5 in each site. In sites Colina, Melipilla and San Jose de Maipo, fossil fuel combustion contributions to PM2.5 were 26 % (15.9 μg m−3), 22 % (9.9 μg m−3), and 22 % (7.8 μg m−3), respectively. Wood burning contributions to PM2.5 were 22 % (13.4 μg m−3), 19 % (8.9 μg m−3) and 22% (7.3 μg m−3), respectively.This methodology generates a joint source apportionment of eBC and PM2.5, which is consistent with available chemical speciation data for PM2.5 in Santiago.

Source apportionment of black carbon and the impact of COVID-19 lockdown over a semi-urban location in India

To reduce emissions and thereby decrease the effect of black carbon (BC) on human health and the climate, the knowledge of BC concentrations and quantification of its contributions from different sources are necessary for establishing strategies for policymakers. The lockdown due to the COVID-19 pandemic has provided a unique scenario to analyze the impact of anthropogenic activities on BC concentration and their sources. In this study, the variation in BC mass concentration (eBC), its source apportionment, absorption angstrom exponent and their inter-annual variations, and the impact of COVID-19 lockdown on BC are analyzed using a six-year observation of eBC (from the year 2016–2021) over a semi-urban location (Vijayawada (16.44°N, 80.62°E), 30m a.m.s.l) in India. BC mass concentration peaks during the morning (around 06:00–08:00 LT) and evening (after 18:00 LT) hours and is low during the daytime. High eBC is observed during the winter season whereas low eBC during the monsoon season. The source apportionment of BC is carried out using the aethalometer model and it shows that the major source of BC over the site is fossil fuel combustion (>60%) along with a non-negligible contribution from biomass burning (<40%). This result is supported by the absorption angstrom exponent values of less than 1.6 during all seasons. A significant decrease (30%) in the total eBC over the site is observed during the COVID-19 lockdown days. It clearly shows the impact of the reduction in the contribution from anthropogenic activities mainly vehicular and industrial emissions (fossil fuel combustion) on the BC concentration. Interestingly, even after significant reduction of fossil fuel source emission during the lockdown, 53% of BC over the observational site is still contributed by fossil fuel combustion. This obviously shows the dominance of long-range transported BC due to fossil fuel combustion over the observational site.

Impact of long-range transport on black carbon source contribution and optical aerosol properties in two urban environments

Urban areas, as major sources of aerosol black carbon emissions, contribute to increased pollution levels in surrounding regions by air mass long-range transport, which should be taken into account in implementation of emission-reduction strategies. Properties of light-absorbing aerosol particles and a novel approach to assess the impact of long-range transport on black carbon (BC) pollution in two under-investigated urban environments: Warsaw (Poland, Central Europe) and Vilnius (Lithuania, North-Eastern Europe) are presented. During the warm season of May–August 2022, BC mass concentration and aerosol optical properties: the scattering Ångström exponent (SAE), absorption Ångström exponent (AAE), and single scattering albedo (SSA) were investigated. Generally, the mean BC mass concentration was higher at the more polluted site in Warsaw (1.07 μg/m3) than in Vilnius (0.77 μg/m3). The BC source apportionment to biomass burning (BCBB) and fossil fuel combustion (BCFF) showed similar contributions for both sites with BCBB (13–19%) being significantly lower than BCFF (81–87%). A uniform flow of air masses transporting aerosol particles over long distances to both sites was observed for 42% of the days. It affected BC mass concentration as follows: BC decrease was found similar at both sites (42% in Warsaw, 50% in Vilnius) but increase was twice higher in Vilnius (64%) than in Warsaw (30%). Despite variations in BC mass concentration, both sites exhibited a comparable abundance (90%) of submicron (SAE<1.3), BC-dominated (AAE<1.5) particles. The mean SSA was very low (0.69 ± 0.1 in Warsaw, 0.72 ± 0.1 in Vilnius), which indicates a very strong contribution of light-absorbing aerosol particles in both environments. The local episodes of biomass burning due to celebrations of May Days on 1st – 3rd May in Warsaw and Midsummer on 24th June in Vilnius showed similar aerosol properties in both cities (1.5<AAE<1.7, 1.7<SAE<2.2) but were highly different than any other during the entire campaign.

Characteristics and Source Apportionment of Black Carbon Over the Eastern Tibetan Plateau

As the most important absorbing aerosol, black carbon (BC) can affect radiation, clouds, and surface snow cover over the Tibetan Plateau. In this study, the BC mass concentrations were measured using a seven-channel aethalometer (AE-33) in Litang County over the eastern Tibetan Plateau from July 5 to September 5, 2017. The aethalometer model, potential source contribution function (PSCF), and concentration-weighted trajectory (CWT) models were used to analyze the variation characteristics, potential sources, and affecting areas of BC. The results showed that the mass concentration of ρ(BC) in Litang ranged from 0.4 to 4699.8 ng·m-3, with an average value of 816.4 ng·m-3, accounting for 5.96% of PM2.5. The average mass concentrations of ρ(BCliquid) and ρ(BCsolid) in Litang were 486.1 ng·m-3 and 398.5 ng·m-3, respectively, with a C of 0.51. The ρ(BC) mass concentration was mainly distributed from 0-2000 ng·m-3, which accounted for 92.5% of the total observation period. The diurnal variation in BC, BCliquid, and BCsolid showed a bimodal distribution, with the peaks appearing at 08:00 and 20:00, respectively. The first peak was mainly related to traffic sources and incomplete combustion of carbonaceous materials, whereas the second peak was mainly related to incomplete combustion of carbonaceous materials. The potential sources and affecting areas of PM2.5 and BC were different. Imports from abroad had a greater impact on the concentrations of PM2.5 and BC in Litang, and the affecting areas were mainly transmitted to the northeast in China. The high-value centers were mainly concentrated in the surrounding areas of Litang.

Performance evaluation of portable dual-spot micro-aethalometers for source identification of black carbon aerosols: application to wildfire smoke and traffic emissions in the Pacific Northwest

Abstract. Black carbon (BC) is a component of particulate matter, emitted from the incomplete combustion of carbonaceous fuels. The presence of BC in the atmosphere can disrupt the atmospheric radiation budget, and exposure to BC can adversely affect human health. Multi-wavelength light-absorption-based dual-spot aethalometers can be used to quantify the source and characteristics of BC from traffic or biomass-burning-based sources. However, aethalometer measurements are affected by artifacts such as aerosol loading and light scattering; hence, they often need correction to reduce measurement uncertainty. This work assesses the performance of the recently developed portable aethalometer (MA300, AethLabs). Due to their portability and ease of usage, MA300s can be suitable for mobile and personal exposure monitoring. Here, we evaluate BC concentration and source apportionment accuracy of three MA300 units relative to a widely used aethalometer, the AE33 (Magee Scientific). Synchronous field measurements were performed at a major traffic intersection during regular and wildfire-smoke-affected days in Vancouver, Canada. We find that MA300-reported BC mass concentrations were strongly correlated (Slope range between 0.73 and 1.01, with R2 = 0.9) compared to the reference instrument, yet there is visible instrumental variability in the normalized concentrations (5 %) across three units. The mean absolute error of MA300-reported BC concentrations ranged between 0.44–0.98 µg m−3, with the highest deviations observed in wildfire-smoke-affected polluted days. From the aerosol light absorption measurement perspective, MA300s tend to underestimate the absorption coefficients (babs) across the five wavelengths. UV channel light absorption results were subjected to the highest amount of noise and were found to be consistently underestimating in all the MA300 units, leading to systematic bias in source apportionment analysis. Absorption Ångström exponent values from the MA300 units were able to capture the variability of aerosol sources within a day, with a mean value of 1.15 during clean days and 1.46 during wildfire-smoke-affected days. We investigated the application of the latest non-linear aethalometer correction protocols in the MA300 and found that flow fluctuations enhanced noise across all channels, compared to onboard instrument correction. We also identify that the UV (λ = 370 nm) channel absorption measurements are most sensitive to instrumental artifacts during the wildfire-smoke-affected period. Hence, as an alternative to traditional UV and IR (λ = 880 nm)-based BC source apportionment methods, in this work, we tested the blue (λ = 470 nm) and IR wavelengths for BC source apportionment calculation. When the blue–IR-based source apportionment technique is adopted instead of the UV–IR, there is a 10 % (on average) decrease in the percentage difference of the apportioned components from the reference monitor.

Source apportionment of black carbon aerosols by isotopes (14C and 13C) and Bayesian modeling from two remote islands in east Asian outflow region

We report the results of source apportionment of combustion-derived black carbon (BC), in PM2.5 aerosols collected from the East Asian continental outflow region at two islands; Okinawa and Fukue during the period from October 2009 to May 2010. The 14C contents of BC from Okinawa (Cape Hedo) and Fukue islands (Fukue) varied from 24.4 to 34.2 pMC and from 18.1 to 43.0 pMC, respectively. Source apportionment of BC was conducted by using a simple 14C mass balance model and a dual-isotope Bayesian Markov chain Monte Carlo model. Biomass combustion contributions (e.g., wood fuel and crop residues) were 23–31 % (mean 27 ± 3 %) at Cape Hedo and 15–38 % (mean 27 ± 12 %) at Fukue. Both sites were equally affected by biomass combustion, whose levels are similar to those observed in the hotspot regions (megacities) in China. Fossil fuel contributions (e.g., oil, gasoline, and diesel) were 69–77 % (mean 74 ± 3 %) with 2–69 % from coal and 3–76 % from liquid fossil at Cape Hedo, and 55–85 % (mean 73 ± 12 %) at Fukue with 3 % from coal and 53–56 % from liquid fuel for the early winter. Those variations for both sites showed significantly different source region-specific trends and this trend was also consistent with the results of the air mass trajectory analysis with a higher contribution of coal-BC from North China including Beijing, and East China including Shanghai. In spring, we found a higher contribution of liquid fossil fuel combustion (e.g., traffic) over the East China Sea, including Pacific air masses, suggesting that the possible contribution of ship emissions was relatively high. Although our results for isotopes-based source apportionment of BC are preliminary, these findings suggest that long-term monitoring of BC aerosols, even in remote sites of Asian outflows, and source-specific descriptions of BC are important to improve climate models. We also recommend further measurements for implementing regionally tailored mitigation.

Source apportionment of black carbon and combustion-related CO2 for the determination of source-specific emission factors

Abstract. Black carbon (BC) aerosol typically has two major sources in the urban environment: traffic and domestic biomass burning, which has a significant contribution to urban air pollution during the heating season. Traffic emissions have been widely studied by both laboratory experiments (individual vehicle emission) and real-world measurement campaigns (fleet emission). However, emission information from biomass burning is limited, especially an insufficiency of experimental results from real-world studies. In this work, the black carbon burden in the urban atmosphere was apportioned to fossil fuel (FF) and biomass burning (BB) related components using the Aethalometer source apportionment model. Applying the BC source apportionment information, the combustion-related CO2 was apportioned by multilinear regression analysis, supposing that both CO2 components should be correlated with their corresponding BC component. The combination of the Aethalometer model with the multilinear regression analysis (AM-MLR) provided the source-specific emission ratios (ERs) as the slopes of the corresponding BC–CO2 regressions. Based on the ER values, the source-specific emission factors (EFs) were determined using the carbon content of the corresponding fuel. The analysis was carried out on a 3-month-long BC and CO2 dataset collected at three monitoring locations in Ljubljana, Slovenia, between December 2019 and March 2020. The measured mean site-specific concentration values were in the 3560–4830 ng m−3 and 458–472 ppm ranges for BC and CO2, respectively. The determined average EFs for BC were 0.39 and 0.16 g(kg fuel)−1 for traffic and biomass burning, respectively. It was also concluded that the traffic-related BC component dominates the black carbon concentration (55 %–64 % depending on the location), while heating has the major share in the combustion-related CO2 (53 %–62 % depending on the location). The method gave essential information on the source-specific emission factors of BC and CO2, enabling better characterization of urban anthropogenic emissions and the respective measures that may change the anthropogenic emission fingerprint.

Characterization and source apportionment of black carbon over a valley glacier at transitional climatic zone of the central-western Himalaya

Characterization and source apportionment of black carbon over a valley glacier at transitional climatic zone of the central-western Himalaya

High concentration of black carbon in northern Pakistan: Characteristics, source apportionment and emission source regions

Atmospheric Black Carbon (BC) is one of the absorbing components of solar radiation which potentially affects human health and regional climate. In the current study, BC mass concentrations were regularly observed for pre-monsoon and monsoon seasons using the seven-channel aethalometer (AE-33) over Peshawar, Pakistan. The scarcity of BC measurement in this region is critical for air quality assessment, hence providing much importance to this article for control policy recommendations. The monthly mean BC showed a maximum value of 12.1 ± 5.4 μg/m3 during March and a minimum value of 6.4 ± 3.1 μg/m3 during July. The bimodal diurnal BC concentration was observed in between 05:00–08:00 and 20:00–24:00 LST having a maximum night/day ratio of 3.4 during April. Furthermore, the weekdays BC concentration was higher than weekend days having the highest weekdays concentration during March (12.9 ± 5.6 μg/m3) and the lowest concentration during July (6.9 ±0 .9 μg/m3). Moreover, BC contributed maximum of 22% to PM2.5 during April and minimum of 7% during June. The source apportionment of BC revealed that maximum value of BC emitted from fossil fuel (BCFF) and biomass burning (BCBB) were 9.90 ± 0.50 μg/m3 and 2.61 ± 0.49 μg/m3 during March showed a clear dominancy of BCFF over BCBB emission. Further the highest percentage contribution of BCFF and BCBB were found to be 80.45% and 22.27% to total BC during May and April, respectively. Finally, the cluster trajectory analysis showed that majority of the air pollutants were due to local emission rather than long range transport.

Characterizing the source apportionment of black carbon and ultrafine particles near urban roads in Xi'an, China

Better knowledge of the sources of black carbon (BC) and ultrafine particles (UFPs) in urban roadway region will provide helpful information for improving road air pollution caused by vehicle emissions. For this purpose, we conducted daily observation of BC and UFPs at two trafficked sites (intersection and roadside), and a background site in Xi'an, China. The concentration data of BC and UFPs measured were combined with Aethalometer model and UFPs source apportion model, to determine and analyze the sources of BC in an urban road region. Further, the source and variation characteristics of primary and secondary UFPs at the roadside sites were clarified. The results showed that average BC concentrations at the intersection, roadside, and background were respectively 3577 ± 2771, 3078 ± 2343, and 1914 ± 1229 ng/m3. The BC source apportionment results revealed contribution rates of on-board fossil fuel combustion (BCff) at the intersection and near the road of ca. 78.7% and 73.6%, respectively. Moreover, the proportion of particles number concentrations directly emitted from vehicles and nucleated upon emission (47%) was lower than that of particles formed during the dilution and cooling of vehicle emissions and by in-situ new particle formation (53%) at the roadside site. At 49%, the proportion of primary particles number was slightly higher at the intersection. The impacts of new particle-formation events on the diurnal variation of secondary particles were explored. Generally, the majority of BC originated from traffic exhausts, while the secondary particles from non-traffic sources are dominant at the road intersections. By providing a better understanding of near-road pollution issues, this study's findings can be useful for taking effective regulatory efforts to improve air quality and reduce people's exposure to traffic-pollutants in an urban environment.

Stable carbon isotopes trace the effect of fossil fuels on fractions of particulate black carbon in a large urban lake in China.

Black carbon (BC), the highly recalcitrant aromatic carbonaceous from the incomplete combustion of fossil fuel and biomass, is an important carbon sink in carbon cycle. Char and soot, the main components of BC, have significantly different origin and physicochemical characteristics (particle sizes and resultant transportability). The limited understanding of char and soot sources leads to poor insight into the effect of BC on carbon cycle. Sources of char and soot were investigated in this study using stable carbon isotopes to study the effect of BC on the organic carbon pool in a lake, thereby improving the knowledge of lacustrine carbon cycling. The concentration of BC in Taihu Lake ranged from 0.0 to 0.7mg·L-1and accounted for 10.9±4.7% of the particulate organic carbon. The spatial-mean δ13C values of BC, char, and soot were -23.2±2.0‰, -23.5±2.2‰, and -22.9±1.6‰, respectively. The BC in water was primarily derived from fossil fuels (66.0±9.3%), with liquid fossil fuel accounting for 48.2±13.2% of the BC. The contribution of liquid fossil fuel to soot (49.3%) was much higher than that to char (36.1%); correspondingly, the contributions of biomass and coal to soot (29.2% and 21.5%) were lower than those to char (38.1% and 25.8%). The contribution of liquid fossil fuel combustion to organic carbon (OC), char, and soot gradually increased from 31.9% to 49.3%. Biomass and coal combustion primarily contributed to char (38.1% and 25.8%) and OC (37.5% and 30.6%). The source apportionment of BC, char, and soot revealed the influence of anthropogenically driven BC, char, and soot on the lake and, by extension, to the global carbon cycle.

Carbonaceous aerosol source apportionment and assessment of transport-related pollution

Diesel vehicles are one of many sources of black carbon (BC) emissions in Europe; nevertheless, due to recent changes in fuel composition towards renewable fuel such as biodiesel, advances in engine design and pollution control technology, BC and organic carbon (OC) emissions may worsen air quality and encourage global warming. As there are no regulatory terms on BC mass concentration levels, assessment of pollution sources is crucial for air quality improvement policies and mitigation of climate change. BC mass concentration and aerosol optical absorption were derived using 7-wavelenght Aethalometer during 3 measurement campaigns in 2014, 2017, and 2020. BC source apportionment analysis was performed using 18 combinations of absorption Ångström exponent (AAE) values for assessing BC to fossil fuel combustion and biomass burning. The choice of the most suitable AAE combination (0.9 and 2.2, respectively) was supported by organic aerosol (OA) source apportionment results. AAE value for transport exhaust emission (0.95) from locally available diesel fuel was established using (CI) 1.9 TDI engine with different engine torque regimes and 7-wavelenght Aethalometer. Statistically and experimentally obtained values were compared and showed great agreement. Subsequently, a statistically obtained AAEtr value was used for BC source apportionment and long-term analysis. A significant increase in the contribution of transport-related BC contribution was observed between years 2014 and 2020 (from 51% to 65%) which was associated with a boost in the use of diesel vehicles (by 83.9% of diesel passenger cars comparing 2014 and 2020) and growing diesel fuel consumption. These findings underline the diesel transport-induced problem for local air quality together with its impact on atmospheric radiative balance and raise concerns for public health.

Characteristics and Source Apportionment of Black Carbon in the North China Plain

Characteristics and Source Apportionment of Black Carbon in the North China Plain

Dual-carbon isotope constraints on source apportionment of black carbon in the megacity Guangzhou of the Pearl River Delta region, China for 2018 autumn season

Black carbon (BC) aerosol negatively affects air quality and contributes to climate warming globally. However, little is known about the relative contributions of different source control measures to BC reduction owing to the lack of powerful source-diagnostic tools. We combine the fingerprints of dual-carbon isotope using an optimized Bayesian Markov chain Monte Carlo (MCMC) scheme and for the first time to study the key sources of BC in megacity Guangzhou of the Pearl River Delta (PRD) region, China in 2018 autumn season. The MCMC model-derived source apportionment of BC shows that the dominant contributor is petroleum combustion (39%), followed by coal combustion (34%) and biomass burning (27%). It should be noted that the BC source pattern is highly sensitive to the variations of air masses transported with an enhanced contribution of fossil source from the eastern area, suggesting the important impact of regional atmospheric transportation on the BC source profile in the PRD region. Also, we further found that fossil fuel combustion BC contributed 84% to the total BC reduction during 2013–2018. The response of PM2.5 concentration to the 14C-derived BC source apportionment is successfully fitted (r = 0.90) and the results predicted that it would take ∼6 years to reach the WHO PM2.5 guideline value (10 μg m−3) for the PRD region if the emission control measures keep same as they are at present. Taken together, our findings suggest that dual-carbon isotope is a powerful tool in constraining the source apportionment of BC for the evaluations of air pollution control and carbon emission measures.

Source apportionment of black carbon using light absorption measurement and impact of biomass burning smoke on air quality over rural central Taiwan: A yearlong study

Biomass burning episodes are critical particulate matter (PM) issues in Taiwan. The occurrence patterns of biomass burning events through long-term PM monitoring are worth further exploration. This study monitored PM10, PM2.5, and black carbon (BC) over one year in central Taiwan. The source apportionment of BC was examined using light absorption techniques and divided into fossil fuel combustion (BCf) and biomass burning (BCb). The monitoring results showed that the annual average PM10, PM2.5, and BC mass concentrations were 45.4 μg/m3, 19.8 μg/m3, and 0.79 μg/m3, respectively, while the annual average ratio of BC/PM2.5 was 0.044. Furthermore, BCf was remarkably higher than BCb, accounting for 89% of the total BC mass. However, it was noticed that biomass burning smoke impacted the air quality by enhancing PM10, PM2.5, and BCb over monitoring location. There were 14.4% of hourly PM10 events (≥125 μg/m3) and 10.0% of hourly PM2.5 events (≥35 μg/m3) resulting from biomass burning episodes at this monitoring site in one-year observation. The hourly average PM10 and PM2.5 concentrations during these biomass burning episodes were 2.1 and 2.3 times higher than the annual average PM10 and PM2.5 concentrations. During severe biomass burning episodes, high levels of human carcinogens, such as 1, 3-butadiene, benzene, and isoprene were also observed. The results demonstrate that air quality is severely degraded during biomass burning episodes. Therefore, further research is required to understand the effects of biomass burning events on the residents' acute and chronic health conditions.

Long‐Term Variation and Source Apportionment of Black Carbon at Mt. Waliguan, China

AbstractBlack carbon (BC) is a significant driver of global climate change, and its long‐term variation is affected by a combination of anthropogenic activities and meteorological diffusion conditions. However, distinguishing the effects of these two factors on BC variation has proven difficult. In this study, we used the China Black Carbon Observational Network data set to assess the diurnal, seasonal, and long‐term BC trends at Mt. Waliguan (WLG) from 2008 to 2017. The mean BC concentration at WLG was 449 ± 366 ng/m3, with a decreasing trend of 2 %yr−1, which was mainly related to emission reduction measures in China. The BC concentration at WLG was higher under easterly air masses than that under westerly air masses, which suggests that the former are conducive to BC transport from the highly polluted eastern regions. Due to the origin and velocity of air masses, the BC concentration at WLG in summer is higher than that in winter. The intensity of the Tibetan Plateau monsoon had an important positive influence on the easterly air masses frequency, which modulated BC transport to WLG in summer. According to the concentration‐weighted trajectory analysis, the high‐potential BC source regions were distributed in Lanzhou, Chengdu, and Xi'an urban agglomerations as well as in northern India. Community Atmosphere Model 5 simulations with a BC‐tagging technique inferred North Central China, Northwest China, and Indian Peninsula to be the major BC source regions to WLG, accounting for 56.1%, 17.5%, and 12.1% of the total BC, respectively.

Sources of black carbon at residential and traffic environments obtained by two source apportionment methods

Abstract. This study investigated the sources of black carbon (BC) at two contrasting urban environments in Helsinki, Finland: residential area and street canyon. The measurement campaign in the residential area was conducted in winter–spring 2019, whereas in the street canyon the measurements were carried out in autumn 2015. The sources of BC were explored by using positive matrix factorization (PMF) for the organic and refractory black carbon (rBC) mass spectra collected with a soot particle aerosol mass spectrometer (SP-AMS). Based on the PMF analysis, two sites had different local BC sources; the largest fraction of BC originated from biomass burning at the residential site (38 %) and from the vehicular emissions in the street canyon (57 %). Also, the mass size distribution of BC diverged at the sites as BC from traffic was found at the particle size of ∼100–150 nm whereas BC from biomass combustion was detected at ∼300 nm. At both sites, a large fraction of BC was associated with urban background or long-range-transported BC indicated by the high oxidation state of organics related to those PMF factors. The results from the PMF analysis were compared with the source apportionment from the Aethalometer model calculated with two pairs of absorption Ångström values. It was found that several PMF factors can be attributed to wood combustion and fossil fuel fraction of BC provided by the Aethalometer model. In general, the Aethalometer model showed less variation between the sources within a day than PMF, indicating that it was less responsive to the fast changes in the BC sources at the site, or it could not distinguish between as many sources as PMF due to the similar optical properties of the BC sources. The results of this study increase understanding of the limitations and validity of the BC source apportionment methods in different environments. Moreover, this study advances the current knowledge of BC sources and especially the contribution of residential combustion in urban areas.