Black Carbon Mass Concentration Research Articles

Trends of Atmospheric Black Carbon Concentration over the Bengaluru

This study investigates the spatial and temporal variations of atmospheric black carbon (BC) concentrations in Bangalore, focusing on the period from June 2018 to May 2020. BC mass concentrations were measured using a portable micro-Aethalometer (model: AethLabs AE-51) at seven different locations, representing a range of land use types from rural to urban areas. The study aimed to assess BC pollution levels, identify hotspots, and understand the factors influencing BC concentrations. The results revealed significant variations in BC concentrations among the different locations. The highest BC concentrations were observed in urban traffic and industrial areas, with average concentrations of 6.21 µg/m³ and 6.78 µg/m³, respectively. Urban centres also exhibited high BC levels, with an average concentration of 7.40 µg/m³. In contrast, rural areas recorded the lowest BC concentrations, with an average of 2.51 µg/m³. These findings highlight the influence of anthropogenic activities and land use patterns on BC pollution levels. Diurnal variations in BC concentrations exhibited distinct patterns, with significant peaks during morning and evening hours, primarily associated with increased traffic emissions. The study also identified seasonal trends, with higher BC concentrations observed during winter months, attributed to stable atmospheric conditions and increased fuel consumption for heating purposes. Notably, BC concentrations were generally lower during summer months due to higher wind speeds and increased vertical mixing of pollutants. The findings of this study emphasize the need for targeted mitigation strategies to reduce BC pollution in Bangalore. The identified hotspots, such as urban traffic and industrial areas, require specific attention to mitigate the adverse health and environmental effects of BC emissions. Furthermore, the study underscores the importance of comprehensive air pollution management approaches that consider both local emissions and meteorological factors to effectively tackle BC pollution.

Synergic use of in-situ and remote sensing techniques for comprehensive characterization of aerosol optical and microphysical properties

We report on importance of conducting comprehensive studies of atmospheric aerosol particles, which cannot be done if information from various complementary sensors is unavailable. We present an example for such application and recommend on the types of sensors that should be used in view of the ACTRIS and RI-URBANS new strategies for monitoring at supersites. Although active and passive remote sensing data was not available in continuous mode, we show that synergic use of them with in-situ observations allows for comprehensive study of temporal and height-resolved distribution of aerosol in the lower troposphere and it can be successfully combined to assess biomass burning impact on air quality and optical properties.The analysed period was divided into three episodes based on the measured black carbon (BC) concentration and the prevailing wind direction. The dominant 72-h backward trajectories were ending in western Europe, mid-Atlantic and western Russia, respectively, The in-situ measured mass concentrations of BCtotal and BC apportioned to biomass burning as well as particulate matter (PM) concentrations in accumulation mode were twice higher during the first and last episodes compared to the second episode, representing long-range transport from different source regions. The obtained complementary surface, column-integrated, and layer-derived size distributions and other parameters demonstrate the added value of multisensor analyses.

Assessment of aerosol optical and physical properties and implications for radiative effects over the semiarid region of Indo‐Gangetic Basin

This study assesses the physical and optical properties and estimated the radiative forcing of aerosol at Agra over the Indo‐Gangetic Basin (IGB) during July 2016–December 2019 using black carbon (BC) mass concentration (AE‐33 aethalometer), data sets from satellite and model simulations. The optical properties of aerosol and radiative forcing have been measured by the Optical and Physical Properties of Aerosols and Clouds (OPAC) and Santa Barbara Discrete Ordinate Radiative Transfer Atmospheric Radiative Transfer (SBDART) model. The high BC mass concentration has been observed in November and lowest in August. An adverse meteorological condition due to a combination of temperature and low wind speed results in poor dispersion in the wintertime is a common factor for high concentration level pollutants over Agra. The diurnal and temporal cycle of BC mass concentration exhibits a high concentration at nighttime due to the lower atmospheric boundary layer. The seasonal variation of absorption coefficient (βabs) and Absorption Angstrom Exponent (AAE) is found to be higher during post‐monsoon and lowest in monsoon season. This suggests that black carbon concentration over Agra is mainly generated from crop burning, waste burning, automobile exhaust and long‐range transport from Punjab and Haryana as the present site is downwind. OPAC‐derived aerosol optical depth (AOD), single‐scattering albedo (SSA), Angstrom Exponent (AE) and asymmetry parameter (AsyP) were estimated to be 0.57 ± 0.07, 0.78 ± 0.16, 0.99 ± 0.21 and 0.81 ± 0.15, respectively. AOD and AE from the OPAC and the moderate resolution imaging spectroradiometer (MODIS) have shown the consistent relationship. The mean radiative forcing is 18.3 ± 2.1 W m−2 at the top of the atmosphere while, at the surface, net radiative forcing is −42.4 ± 7.2 and 59.1 ± 6.5 W m−2 at the atmosphere during the study period. Vertical profiles were estimated using the observations from Cloud‐Aerosol Lidar and Infrared Pathfinder Satellite Observation (CALIPSO) satellite and the change in heating rate from the SBDART model over Agra.

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.

Effectiveness of equipping bus stop shelters with cooling and filtering systems in a city with tropical climate

PurposeWaiting for a bus may represent a period of intense exposure to traffic particles in hot and noisy conditions in the street. To lessen the particle load and tackle heat in bus stops a shelter was equipped with an electrostatic precipitator and a three-step adiabatic cooling system capable of dynamically adjust its operation according to actual conditions. This study evaluates the effectiveness of the Airbitat Oasis Smart Bus Stop, as the shelter was called, to provide clean and cool air.Design/methodology/approachThe particle exposure experienced in this innovative shelter was contrasted with that in a conventional shelter located right next to it. Mass concentrations of fine particles and black carbon, and particle number concentration (as a proxy of ultrafine particles) were simultaneously measured in both shelters. Air temperature, relative humidity and noise level were also measured.FindingsThe new shelter did not perform as expected. It only slightly reduced the abundance of fine particles (−6.5%), but not of ultrafine particles and black carbon. Similarly, it reduced air temperature (−1 °C), but increased relative humidity (3%). Its operation did not generate additional noise.Practical implicationsThe shelter's poor performance was presumably due to design flaws induced by a lack of knowledge on traffic particles and fluid dynamics in urban environments. This is an example where harnessing technology without understanding the problem to solve does not work.Originality/valueIt is uncommon to come across case studies like this one in which the performance and effectiveness of urban infrastructure can be assessed under real-life service settings.

Key drivers to heterogeneity evolution of black carbon-containing particles in real atmosphere

The evolution of black carbon (BC) particles during atmospheric aging led to the complexity of their environmental and climate effect assessment. This study simultaneously measured the heterogeneous distribution of multi-level microphysical properties of BC-containing particles (i.e., BC mass concentration, coating amounts, and morphology) by a suite of state-of-the-art instruments, and investigated how atmospheric processing influence these heterogeneities. Our field measurements show that the mixing states of atmospheric BC-containing particles exhibit a clear dependence on BC core diameters. The particles with small BC core sizes (80–160 nm) are coated and reshaped more rapidly in real atmosphere, with coating-to-BC mass ratios (MR) and non-spherical fractions of 5.1 ± 1.2 and 61 ± 19 %, respectively. Conversely, the particles with large core sizes (240–320 nm) are thinly coated and fractal, with MR and non-spherical fractions of 4.0 ± 0.3 and 74 ± 15 %, respectively. Furthermore, primary emissions result in low heterogeneity in coating amount but great heterogeneity in morphology between BC-containing particles of different sizes, while photochemical processing would enhance heterogeneity in coating amount but weaken the heterogeneity in morphology. Overall, our field measurement of multi-level microphysical properties highlights that BC core size and atmospheric processing are the key factors that drive the heterogeneity evolution of BC-containing particles in real atmosphere.

Observational evidence of the regional transported black carbon in high layer over Beijing

The mass concentration, size distribution and mixing state of refractory black carbon (rBC) particles, together with other pollutants and meteorological variables, were observed at a station with a height of 528 m above ground to understand source of rBC particles over Beijing. Here we present observational evidences that regional transported rBC is an important source of rBC in high layer over Beijing. In our observations, the mass concentration of rBC increased from 1.0 μg m−3 to 4.6 μg m−3 during period with strong regional transport of pollutants, but decreased to 1.8 μg m−3 when regional transport weakened. Such trend was different with local emitted NOx, but consistent with regional transported SO2. Further analyses indicated that the transported rBC particles were highly aged; the ratio of “thickly” coated rBC in total rBC (fBC) increased from 52.4% to 71.3% during period with strong regional transport, and then decreased slightly to 66.9% when regional transport weakened, likely caused by supplement of freshly emitted local BC particles. The aged rBC particles own enhanced light absorbing capacity, which may exert more important role in weakening atmospheric diffusion capacity and aggravating surface haze pollution, and hence should be concerned in future pollution mitigation.

Satellite (GOSAT-2 CAI-2) retrieval and surface (ARFINET) observations of aerosol black carbon over India

Abstract. Light-absorbing black carbon (BC) aerosols strongly affect Earth's radiation budget and climate. This paper presents satellite retrieval of BC over India based on observations from the Cloud and Aerosol Imager-2 (CAI-2) on board the Greenhouse gases Observing Satellite-2 (GOSAT-2). To evaluate and validate the satellite retrievals, near-surface BC mass concentrations measured across the Aerosol Radiative Forcing over India NETwork (ARFINET) of aerosol observatories are used. Then the findings are extended to elucidate global BC features. The analysis reveals that this satellite retrieval clearly demonstrates the regional and seasonal features of BC over the Indian region, similarly to those recorded by surface observations. Validation and closure studies between the two datasets show RMSE &lt; 1 and absolute difference below 2 µg m−3 for &gt; 60 % of simultaneous observations, exhibiting good associations for December, January, and February (R of approximately 0.73) and March, April, and May (R approx. 0.76). Over the hotspot regions of India, satellite retrievals show a soot volume fraction of approx. 5 %, columnar single-scattering albedo of approx. 0.8, and BC column optical depth of approx. 0.1 during times of the highest BC loading, which are comparable to other in situ and satellite measurements. In terms of global spatiotemporal variation, satellite retrievals show higher BC occurring mostly in areas where biomass burning is intense. Overall, this study highlights the effectiveness of satellite retrieval of BC, which can be used effectively for the regular monitoring of BC loading attributable to vehicular, industrial, or biomass burning activities.

The variability of mass concentrations and source apportionment analysis of equivalent black carbon across urban Europe

This study analyzed the variability of equivalent black carbon (eBC) mass concentrations and their sources in urban Europe to provide insights into the use of eBC as an advanced air quality (AQ) parameter for AQ standards. This study compiled eBC mass concentration datasets covering the period between 2006 and 2022 from 50 measurement stations, including 23 urban background (UB), 18 traffic (TR), 7 suburban (SUB), and 2 regional background (RB) sites. The results highlighted the need for the harmonization of eBC measurements to allow for direct comparisons between eBC mass concentrations measured across urban Europe. The eBC mass concentrations exhibited a decreasing trend as follows: TR > UB > SUB > RB. Furthermore, a clear decreasing trend in eBC concentrations was observed in the UB sites moving from Southern to Northern Europe. The eBC mass concentrations exhibited significant spatiotemporal heterogeneity, including marked differences in eBC mass concentration and variable contributions of pollution sources to bulk eBC between different cities. Seasonal patterns in eBC concentrations were also evident, with higher winter concentrations observed in a large proportion of cities, especially at UB and SUB sites. The contribution of eBC from fossil fuel combustion, mostly traffic (eBCT) was higher than that of residential and commercial sources (eBCRC) in all European sites studied. Nevertheless, eBCRC still had a substantial contribution to total eBC mass concentrations at a majority of the sites. eBC trend analysis revealed decreasing trends for eBCT over the last decade, while eBCRC remained relatively constant or even increased slightly in some cities.

Spatiotemporal analysis of fine particulate matter for India (1980–2021) from MERRA-2 using ensemble machine learning

Particle exposure affects more humans globally than any other air pollutant. However, due to expensive instruments and infrastructural deficiency, a high spatiotemporal network of monitoring stations is not possible, leading to data-scarce regions. Satellite and reanalysis datasets can be implemented to estimate particulate matter, but they do not provide surface concentration and needs to be reconstructed from the components. In this study, a machine learning (ML) framework is implemented to reconstruct PM2.5 from MERRA-2 data components, namely black carbon (BC), organic carbon (OC), dust (DUST), sea salt (SS), and sulfate (SO4) mass concentration. The ground-level data were collected from India's 335 continuous ambient air quality monitoring stations (CAAQMS) and respective MERRA-2 data for 2017–2021 at hourly resolution. Random forest (RF) performs better with train and test scores (R2) of 0.84 and 0.73, respectively, while the empirical equation provides an R2 of only 0.26 on test data. The estimated PM2.5 for Indian states from 1980 to 2021 indicates a significant increase in most cases. However, states in the Indo-Gangetic plain such as Delhi, Punjab, Haryana, and Uttar Pradesh, are the most polluted regions of India. The major shift in concentration is from 2000 onwards, which can be seen as a direct result of the economic liberalization policies implemented in 1991. The results provide evidence for the limitations of the broad application of the empirical equation and the feasibility of ML algorithms as a potential reconstruction technique for developing robust and accurate region-specific models from MERRA-2 data.

Sources, transport pathways and radiative effects of BC aerosol during 2018–2020 at a receptor site in the eastern Indo-Gangetic Plain

This study reports black carbon (BC) characteristics and climate effects for a 22-month period during 2018–2020 at a receptor location in the eastern Indo-Gangetic Plains (IGP). The overall averaged BC mass concentration was 7.8 ± 4.7 μg m−3, and the nighttime average (9.1 ± 6.1 μg m−3) was nearly double that of the daytime (5.8 ± 3.5 μg m−3). BC was most enhanced during winter, with mean concentration (14.3 ± 3.8 μg m−3) higher by 4 times as compared to summer. A two-component mixing model, frequency distribution of the Angstrom exponent, and a simultaneous increase in brown carbon (BrC) absorption coefficient suggested that this enhancement was mostly due to the biomass burning (BB) fraction of BC. CALIPSO-derived products showed that the extinction coefficient was highest at 0.62 ± 0.31 km−1 in winter and lowest at 0.12 ± 0.05 km−1 in summer. Backscatter plots and particle depolarization ratios indicated presence of spherical dust particles during summer and smoke plumes during post-monsoon and winter. Concentration-weighted trajectories (CWTs) helped in quantifying significant contributions of the IGP outflow to BC, BC-BB and BrC absorption. Finally, a large direct radiative forcing of the atmosphere by BC (37 ± 22 W m−2) was estimated via the radiative transfer model SBDART, with an associated atmospheric heating rate of 1.02 K d−1.

Anthropogenic fine aerosol and black carbon distribution over urban environment

Real-time black carbon (BC) and fine particulate matter (PM) were collected from January to December 2017 with a portable Aethalometer and air sampler in the urban environment of Jamshedpur, India. In the present study, the diurnal and seasonal variations of BC and meteorological variables were analysed. The diurnal variation of BC ranged from 2.1 to 15.5 gm-3, with the lowest concentration during the monsoon season and the highest during the winter season, because in monsoon most of the BC and PM are settled down. The annual mean BC mass concentration was observed at 6.22 ± 3.95 µgm−3. While, fine PM2.5 varied from 41.6 to 260.3 µgm-3, with an annual mean of 97.49 ± 63.52 µgm−3. During monsoon, the BC mass concentration shows a value of ˂ 3 µgm−3. Additionally, the percentage contribution of BC in PM2.5 was determined to be around 5.06% (winter), 6.32% (summer), 5.20% (monsoon), and 7.21% (post-monsoon). The change in BC concerning different meteorological parameters was systematically studied, in which an exciting inverse relationship was noticed between BC concentration and temperature. The correlation between BC and wind speed was also established as a negative connection during study periods. It also observed a negative correlation with precipitation. Finally, the air back trajectory was analysed using the Hybrid Single-Particle Lagrangian Integrated Trajectory (HYSPLIT), which revealed that the essential campaign of aerosol-bounded air parcels was mostly coming from the western part of India, with some marine air masses also joining from the Bay of Bengal during summer and post-monsoon. Overall study shows that highest BC and PM2.5 was observed in the winter season because of mixed layer height (MLH).

Sources, size-resolved deposition in the human respiratory tract and health risks of submicron black carbon in urban atmosphere in Pearl River Delta, China

Black carbon (BC) has a significantly negative impact on air quality, climate and human health. Here we investigated the sources and health effects of BC in urban area of the Pearl River Delta (PRD) based on online data measured by Aerodyne soot particle high-resolution time of flight aerosol mass spectrometer (SP-AMS). In urban PRD, BC particles mainly came from vehicle emissions especially heavy-duty vehicle exhausts (contributing 42.9 % of total BC mass concentration), long-range transport (27.6 %), and aged biomass combustion emissions (22.3 %). Indicated by source analysis using simultaneous aethalometer data, BC associated with local secondary oxidation and transport may also be originated from fossil fuel combustion, especially traffic sources in urban and surrounding areas. Size-resolved BC mass concentrations provided by SP-AMS, for the first time to our best knowledge, were used to calculate BC deposition in the human respiratory tract (HRT) of different populations (children, adults, and the elderly) by the Multiple-Path Particle Dosimetry (MPPD) model. We found that submicron BC was deposited more in the pulmonary (P) region (49.0–53.2 % of the total BC deposition dose), while less in the tracheobronchial (TB, 35.6–37.2 %) and head (HA, 11.2–13.8 %) regions. Adults suffered the highest BC deposition (1.19 μg day−1) than the elderly (1.09 μg day−1) and children (0.25 μg day−1). BC deposition rate was greater at night (especially 18:00–24:00) than during the daytime. The maximum deposition in the HRT was found for BC particles around 100 nm, mainly in deeper respiratory regions (TB and P), which may cause more serious health effects. Adults and the elderly group are confronted with the notable carcinogenic risk of BC in the urban PRD, up to 29 times higher than the threshold. Our study emphasizes the need to control BC pollution in the urban area, especially nighttime vehicle emissions.

Black carbon emissions in the rural Indian households: Sources, exposure, and associated threats

In this study, we present the indoor Black Carbon (BC) measurements with the help of Aethalometer (AE‐33) from various sites in Eastern India in a typical kitchen room situated in a rural area. Analysis was done on how various cooking activities performed in the home affected the indoor level of BC. The activities resulting in elevated indoor concentrations included three different periods of cooking breakfast, lunch, and dinner with three different kinds of kitchen structures open, semi‐open and closed kitchen. Close kitchen resulted in the highest BC concentrations, while open kitchen resulted in the lowest level. The burning of low‐grade fuels resulted in the largest increases in indoor BC concentration. We calculated the average BC concentrations for three distinct kitchens, with open kitchens emitting 260.14 μgm−3, semi‐open kitchens emitting 441.14 μgm−3, and closed kitchens emitting 477.25 μgm−3. The biomass burning % was high during the entire research. Because BC mass concentration was found to be high in indoor sampling, as a result, the health risk assessment is also considered to be high in all types of kitchens. As people spend a significant amount of time at home, especially in a future where remote work is anticipated to be easier, finding the activities, sources, and health effects that increase indoor pollution is vital to lowering indoor exposure.

Mutual response hypothesis between surface temperature and aerosol (BC and non-BC) mass concentration observed in an urban environment

The mutual response between near surface aerosol concentration and surface temperature works in a complicated manner. A recent study has introduced a hypothesis of mutual response between surface temperature and near surface black carbon (BC) mass concentration which states that ‘more fall in morning hour surface temperature (T) contribute to the enhancement of BC fumigation peak after the sunrise which positively impacts the extra rise in mid-day temperature over a region during the day time’. Morning hour surface temperature is proportionally linked with the strength of the night time near surface temperature inversion which contributes to the enhancement of the fumigation peak of BC aerosols after the sunrise and the enhanced fumigation peak can impact the degree of the mid-day surface temperature rise by influencing the instantaneous heating. However, it didn't mention the role of non-BC aerosols. Further, the hypothesis was drawn based on the co-located ground-based observations of surface temperature and BC concentration at a rural location of peninsular India. Though, it was mentioned that the hypothesis can be tested independently of locations, but was not thoroughly validated for an urban environment where the loading of both BC and non-BC aerosols are high. In this context, the first objective of the present work is to methodically test the BC –T hypothesis over an Indian metropolitan city, Kolkata, using the suite of measurements obtained from Kolkata Camp Observatory of NARL (KCON) along with other supporting data. In addition, the validity of the hypothesis for the non-BC fraction of PM2.5 aerosols over the same location is also tested. Besides ascertaining the above-mentioned hypothesis over an urban location, it is found that the enhancement of non-BC PM2.5 aerosols peak after the sunrise can negatively influences the mid-day temperature rise over a region during the day time.

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.

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

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

Atmospheric concentrations of black carbon are substantially higher in spring than summer in the Arctic

A key driving factor behind rapid Arctic climate change is black carbon, the atmospheric aerosol that most efficiently absorbs sunlight. Our knowledge about black carbon in the Arctic is scarce, mainly limited to long-term measurements of a few ground stations and snap-shots by aircraft observations. Here, we combine observations from aircraft campaigns performed over nine years, and present vertically resolved average black carbon properties. A factor of four higher black carbon mass concentration (21.6 ng m−3 average, 14.3 ng m−3 median) was found in spring, compared to summer (4.7 ng m−3 average, 3.9 ng m−3 median). In spring, much higher inter-annual and geographic variability prevailed compared to the stable situation in summer. The shape of the black carbon size distributions remained constant between seasons with an average mass mean diameter of 202 nm in spring and 210 nm in summer. Comparison between observations and concentrations simulated by a global model shows notable discrepancies, highlighting the need for further model developments and intensified measurements.

Measurement report: Black carbon properties and concentrations in southern Sweden urban and rural air – the importance of long-range transport

Abstract. Soot, or black carbon (BC), aerosol is a major climate forcer with severe health effects. The impacts depend strongly on particle number concentration, size and mixing state. This work reports on two field campaigns at nearby urban and rural sites, 65 km apart, in southern Sweden during late summer 2018. BC was measured using a single-particle soot photometer (SP2) and Aethalometers (AE33). Differences in BC concentrations between the sites are driven primarily by local traffic emissions. Equivalent and refractory BC mass concentrations at the urban site were on average a factor 2.2 and 2.5, with peaks during rush hour up to a factor ∼4, higher than the rural background levels. The number fraction of particles containing a soot core was significantly higher in the city. BC particles at the urban site were on average smaller by mass and had less coating owing to fresh traffic emissions. The organic components of the fresh traffic plumes were similar in mass spectral signature to hydrocarbon-like organic aerosol (HOA), commonly associated with traffic. Despite the intense local traffic (∼ 30 000 vehicles passing per day), PM1, including organic aerosol, was dominated by aged continental air masses even at the curbside site. The fraction of thickly coated particles at the urban site was highly correlated with the mass concentrations of all measured chemical species of PM1, consistent with aged, internally mixed aerosol. Trajectory analysis for the whole year showed that air masses arriving at the rural site from eastern Europe contained approximately double the amount of BC compared to air masses from western Europe. Furthermore, the largest regional emissions of BC transported to the rural site, from the Malmö–Copenhagen urban area, are discernible above background levels only when precipitation events are excluded. We show that continental Europe and not the Malmö–Copenhagen region is the major contributor to the background BC mass concentrations in southern Sweden.