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Over the years, the Cape Peninsula has seen a rise in the number of fires that occur seasonally. This study aimed to investigate the extent of fire spread and associated damages during the 2023/2024 Cape Peninsula fire events. Remote sensing datasets from Sentinel-5P, Sentinel-2, Moderate Resolution Imaging Spectroradiometer (MODIS), and Modern-Era Retrospective analysis for Research and Applications, Version 2 (MERRA-2) were used. Most of the fires on the northern side of the Cape Peninsula had a short burning span of between 6 and 12 h, but fires with a duration of 12–24 h were minimal. The northern area is composed of low forests and thickets as well as fynbos species, which were the primary fuel sources. Excessive amounts of carbon monoxide (CO) and black carbon (BC) emissions were observed. High speeds were observed during the period of the fires. This is one of the factors that led to the spread of the fire. Relative humidity at 60% was observed, indicating slightly dry conditions. Additionally, the Leaf Water Content Index (LWCI) indicated drier vegetation, enhancing fire susceptibility. High temperatures, low moisture and strong winds were the main drivers of the fire. The Normalized Burn Ratio (NBR) values for the targeted fires showed values close to −1, which signifies presence of a fire scar. The study can be of use to those in the fire management agencies and biodiversity conservation in the region. [ABSTRACT FROM AUTHOR]

In the context of China's "dual carbon" goal, emissions of air pollutants are expected to significantly decrease in the future. Thus, the direct climate effects of black carbon (BC) aerosols in East Asia are investigated under this goal using an updated regional climate and chemistry model. The simulated annual average BC concentration over East Asia is approximately 1.29 μg/m3 in the last decade. Compared to those in 2010–2020, both the BC column burden and instantaneous direct radiative forcing in East Asia decrease by more than 55% and 80%, respectively, in the carbon peak year (2030s) and the carbon neutrality year (2060s). Conversely, the BC effective radiative forcing (ERF) and regional climate responses to BC exhibit substantial nonlinearity to emission reduction, possibly resulting from different adjustments of thermal‐dynamic fields and clouds from BC‐radiation interactions. The regional mean BC ERF at the tropopause over East Asia is approximately +1.11 W/m2 in 2010–2020 while negative in the 2060s. BC‐radiation interactions in the present‐day impose a significant annual mean cooling of −0.2 to −0.5 K in central China but warming +0.3 K in the Tibetan Plateau. As China's BC emissions decline, surface temperature responses show a mixed picture compared to 2010–2020, with more cooling in eastern China and Tibet of −0.2 to −0.3 K in the 2030s, but more warming in central China of approximately +0.3 K by the 2060s. The Indian BC might play a more important role in East Asian climate with reduction of BC emissions in China. Plain Language Summary: Black carbon (BC) aerosols, which are among the air pollutants that will be reduced in China under the "dual carbon" goal, can have an impact on the regional climate by absorbing solar radiation. We use a regional climate model to simulate the climate effect of BC over East Asia under the "dual carbon" goal of China. The results showed that the BC concentration and column burden in East Asia, as well as the instantaneous direct radiative forcing, will decrease significantly under future regional emission reduction policies. However, the effective radiative forcing of BC and regional climate responses do not exhibit simple linear relationships with emissions. The BC‐induced atmospheric thermal‐dynamic anomalies are the main drivers of this nonlinearity. Similarly, BC emissions from India might also influence the East Asian climate. Key Points: The East Asian black carbon (BC) loadings and instantaneous direct radiative forcings significantly decrease under the "dual carbon" goal of ChinaThe BC induced regional climate changes show nonlinear responses to the BC emission reductionThe Indian BC might play an increasingly important role in East Asian climate with decreasing BC emissions in China [ABSTRACT FROM AUTHOR]

AbstractBlack carbon was widely researched due to its significant role on the global carbon cycle and contaminant transport, and most people were concerned about the property of the dissolved black carbon from black carbon. In this work, we focused on the research of the residual those of black carbon. Two kinds of black carbon originated from peanut shell and bamboo were prepared and the corresponding residual black carbons were also obtained by the ultrasonic dissolution process. It was found the chemical and structure properties of residual black carbon changed a lot compared to black carbon. Using methylene blue as a target contaminant, the adsorption capacity of methylene blue by the residual black carbon was greater than that of black carbon. The adsorption capacity of black carbon-bamboo for methylene blue increased from 11.1 mg/g to 16 mg/g after the dissolution process, and the adsorption capacity of black carbon-peanut shell for methylene blue increased from 14 mg/g to 23 mg/g. The various influencing factors, such as the pH, initial concentration, temperature and adsorbent dosage, were systematically studied. The black carbons derived from peanut shell before and after the ultrasonic dissolution process both showed greater adsorption capacities for methylene blue. To further elucidate the methylene blue adsorption process, different kinds of isotherm and kinetics models were applied to simulate the experimental data. The results indicated that the Langmuir isotherm model was suitable to all the carbons before and after the ultrasonic dissolution process, and the pseudo-second-order model showed great simulation for the adsorption of methylene blue. In addition, the analysis of the thermodynamic study revealed that the adsorption processes of methylene blue were endothermic and spontaneous. Overall, results obtained from this work revealed the black carbon after been dissolved showed better adsorption capacity for contaminant. [ABSTRACT FROM AUTHOR]

This study aims to delineate the characteristics of black carbon (BC) in the atmosphere over the urban background environment in Vilnius (Lithuania) from 1 June 2021 to 31 May 2022 using aethalometer (Magee Scientific) measurements. The annual mean concentrations of BC originating from fossil fuels (BCff) and from biomass burning (BCbb) were found to be 0.63 μg m−3 with a standard deviation (SD) of 0.67 μg m−3 and 0.27 µg m−3 (0.35 μg m−3). The further findings highlight the dominance of fossil-fuel-related BC throughout the study period (71%) and the seasonal variability of BC pollution, with biomass-burning-related BC making the largest contribution during the summer season (41%) and the smallest contribution during autumn (23%). This information provides valuable insights into the sources and dynamics of BC pollution in the region. The sources and composition of BC on the days with the highest pollution levels were influenced by a combination of local and regional factors in every season. Additionally, this study employs an advanced approach to understanding urban BC pollution by focusing on high-pollution days (18), identified based on a daily mean BC mass concentration exceeding the 95th percentile, alongside an analysis of overall seasonal and diurnal variations. This methodology surpasses many those of previous urban BC studies, offering a comprehensive examination of the sources and composition of BC pollution. [ABSTRACT FROM AUTHOR]

Mobile monitoring is used as an additional tool to collect air quality data at a high spatial resolution and to complement data from fixed air quality stations. Citizens are interested in contributing to air quality monitoring, and while the availability of low-cost air quality sensors can create opportunities to measure the air quality at a high spatial resolution, the data are often of lower quality, and sensors that measure combustion-related aerosols (like black carbon) are not commonly available. Mobile monitoring using a mid-range instrument can fill this gap. We present the results of a mobile BC (black carbon) monitoring campaign performed by citizens in Mechelen as part of a local citizen observatory (CO), Meet Mee Mechelen, initiated as part of the European H2020 project, Ground Truth 2.0. The goal of the study was two-fold: (1) to propose and evaluate a mobile monitoring method (data collection and data processing) to construct pollution maps of BC concentrations and (2) to demonstrate how to organize community-based air quality monitoring to measure both the spatial and temporal variations in air pollution levels. Measurements were taken during peak hours in four campaigns characterized by different meteorological conditions: October–November 2017, February–March 2018, June–July 2018 and September 2018. The results show large spatial and temporal variabilities. Spatial variability is influenced by traffic volume, stop-and-go traffic and also the building environment and the distance of biking paths from road traffic. The four different campaigns show similar spatial patterns, but due to background and meteorological influences, the absolute concentrations differ between seasons. A rescaling method using data from fixed stations in the air quality monitoring network (AQMN) was presented to construct maps representative of longer periods. This paper shows that mobile measurements can be used by CO to assess the spatial variability of air quality in a city. The data can be used to evaluate mobility plans, carry out hot spot detection, evaluate the exposure of cyclists as a function of cycling infrastructure and perform model validation. However, it is important to use high-quality instruments and apply the correct measurement methodology (number of repetitions, season) to obtain meaningful data. [ABSTRACT FROM AUTHOR]

The Arctic is particularly vulnerable to the impacts of climate change, of which vessel-source black carbon aerosols serving as a prominent catalyst for these changes. This situation is poised to worsen as sea ice melts and shipping lanes change. Rapid action aimed at mitigating short-term climate forcing factors can yield almost immediate climate benefits in the Arctic. This article provides an overview of the legal framework governing black carbon in the Arctic, considering three distinct perspectives: the global, regional, and national dimensions. These perspectives encompass global forums represented by the International Maritime Organization (IMO) and the United Nations Framework Convention on Climate Change (UNFCCC), with a focus on recent developments concerning black carbon governance, notably the amendments to MARPOL Annex VI and Annex I. Regionally, forums represented by the Arctic Council and the European Union are examined. Black carbon emissions exhibit migratory characteristics, yet the primary legal responsibilities for emission reduction are concentrated within Arctic states. Therefore, this article also delves into the laws and practices of Arctic coastal states in their efforts to combat black carbon emissions, using Canada and Norway as examples. The analysis of institutional effectiveness in this article indicates that, at present, specialized legislation on black carbon is either vague or non-existent. The current Arctic ship-source black carbon governance system faces issues related to leadership ambiguity in its institutional structure, a limited scope of responsible entities, and a lack of diverse implementation measures. Simultaneously, the governance system is questioned for having weak or non-legally binding regulations at the level of legal enforcement. The article anticipates the introduction of more mandatory regulations while also encouraging the selection of non-coercive policy tools. Accordingly, this article argues that a coordinated governance system centered on IMO and the Arctic Council needs to be established. Such a framework should adopt a more inclusive approach to stimulate positive interactions between regulations, aiming to create a broader winning alliance based on the existing foundations. [ABSTRACT FROM AUTHOR]

Black carbon (BC) has emerged as an integral part of the global carbon (C) cycle, constituting 12% ± 5% of the organic C pool in rivers and soils, with the potential to generate negative climate feedback. However, its ability to sequester C depends on the recalcitrant nature of BC in the environment, which is under debate. Using CTO‐375 method and by measuring concentrations and isotopic compositions of particulate BC (δ13CPBC), we explore the transformation of particulate black carbon (PBC) along the atmosphere‐river‐ocean continuum. Significantly high δ13CPBC in the ocean compared to rivers and atmospheric particulate matter indicates (a) degradation of PBC, potentially through photodegradation and leaching, and/or (b) availability of an enriched source other than fluvial or aeolian inputs. This evidence for degradation of PBC in aquatic systems warrants rethinking on its C sequestration potential and role in aquatic C biogeochemistry and further raises concerns regarding the use of sedimentary BC as a paleoenvironmental proxy. Plain Language Summary: Particulate black carbon (PBC) forms ∼12% ± 5% of the particulate organic carbon pool in aquatic systems. Black carbon has been considered highly recalcitrant and therefore a potent sink for carbon. Paleo‐environmental and biogeochemical studies have been conducted assuming BC as highly stable and its isotopic composition to remain unaltered after formation. This study explores the variability in stable isotopic composition of PBC in the riverine, atmospheric, and oceanic systems and provides evidence contrary to the general belief of the refractory nature of BC, which warrants revisiting and rethinking of the BC dynamics in aquatic systems. Key Points: Particulate black carbon (PBC) concentration decreases along the river ocean continuumStable carbon isotopic composition of the oceanic PBC pool is higher compared to the riverine and atmospheric poolsIsotopic evidence suggests degradation of PBC with the preferential loss of lighter carbon [ABSTRACT FROM AUTHOR]

• Comparison of portable black carbon monitors with standard aethalometer AE33. • The effect of ambient environment and built-in algorithms were investigated. • Suggestion on application scenario of each micro monitor proposed. Black carbon (BC) is associated with adverse human health and climate change. Mapping BC spatial distribution imperatively requires low-cost and portable devices. Several portable BC monitors are commercially available, but their accuracy and reliability are not always satisfactory during continuous field observation. This study evaluated three models of portable black carbon monitors, C12, MA350 and DST, and investigates the factors that affect their performance. The monitors were tested in urban Beijing, where portable devices running for one month alongside a regular-size reference aethalometer AE33. The study considers several factors that could influence the monitors' performance, including ambient weather, aerosol composition, loading artifacts, and built-in algorithms. The results show that MA350 and DST present considerable discrepancies to the reference instrument, mainly occurring at lower concentrations (0–500 ng/m3) and higher concentrations (2500–8000 ng/m3), respectively. These discrepancies were likely caused by the anomalous noise of MA350 and the loading artifacts of DST. The study also suggests that the ambient environment has limited influence on the monitors' performance, but loading artifacts and accompanying compensation algorithms can result in unrealistic data. Based on the evaluation, the study suggests that C12 is the best choice for unsupervised field measurement, DST should be used in scenarios where frequent maintenance is available, and MA350 is suitable for research purposes with post-processing applicable. The study highlights the importance of assigning portable BC monitors to appropriate applications and the need for optimized real-time compensation algorithms. [Display omitted] [ABSTRACT FROM AUTHOR]

Air pollution around industrial area has become a serious concern for both the public and local government. Thus, research on PM2.5 characterization is urgently needed. This study identifies the concentration and chemical characteristics of PM2.5 to provide an in-depth understanding of the composition of these particles around the largest industrial complex in North Jakarta. Sixty samples of PM2.5 were collected from residential sites around industrial areas in North Jakarta. Samples were collected on Teflon filters using a SuperSASS instrument during the period from February to July 2023, representing the wet and dry seasons. Mass concentrations of PM2.5, black carbon, and 19 chemical elements were determined. The average mass concentration of PM2.5 in the wet and dry seasons was 27.81±11.82 µg/m³ and 46.63±14.37 µg/m³, respectively. Although the concentration of PM2.5 was lower during the wet season, the concentrations of black carbon and certain elements did not decrease significantly. This shows that pollutants play an important role in both seasons in the study location. Sulfur is the most abundant element with the average concentration in the dry season (2,727.89 ng/m³ ) higher than in the wet season (1,983.18 ng/m³ ). The PM2.5 mass reconstruction results show that ammonium sulfate and black carbon have the largest portion of PM2.5 mass. The results are expected to be used as a scientific reference in studying air pollution problems in this region and assist in formulating air protection policies to reduce PM2.5 emissions. [ABSTRACT FROM AUTHOR]

Wildfires frequently occur in Ukraine during agricultural open-burning seasons in spring and autumn. High aerosol concentrations from fire emissions can significantly affect meteorological processes via direct and indirect aerosol effects. To study these impacts, we selected a severe wildfire episode from April 2020 in the Chornobyl Exclusion Zone (CEZ) and its surrounding area as a case study. We employed the Enviro-HIRLAM modeling system to simulate reference (REF) meteorological conditions, along with direct (DAE), indirect (IDAE), and combined (COMB) aerosol effects. In our simulations, black carbon (BC) and organic carbon (OC) comprised 70–80% of all aerosol mass in the region, represented in two layers of higher concentrations: one near the surface and the other 3–4 km above the surface. Our simulations showed that the inclusion of aerosol effects into the modeling framework led to colder (up to −3 °C) and drier (relative humidity drop up to −20%) conditions near the surface. We also observed localized changes in cloudiness, precipitation (mainly redistribution), and wind speed (up to ±4 m/s), particularly during the movement of atmospheric cold fronts. Larger uncertainties were observed in coarser model simulations when direct aerosol effects were considered. Quantifying the aerosol effects is crucial for predicting and promptly detecting changes that could exacerbate unfavorable weather conditions and wildfires. Such knowledge is essential for improving the effectiveness of emergency response measures. [ABSTRACT FROM AUTHOR]

Methodologies across the dispersion preparation, characterization, and cellular dosimetry of hydrophilic nanoparticles (NPs) have been developed and used extensively in the field of nanotoxicology. However, hydrophobic NPs pose a challenge for dispersion in aqueous culture media using conventional methods that include sonication followed by mixing in the culture medium of interest and cellular dosimetry. In this study, a robust methodology for the preparation of stable dispersions of hydrophobic NPs for cellular studies is developed by introducing continuous energy over time via stirring in the culture medium followed by dispersion characterization and cellular dosimetry. The stirring energy and the presence of proteins in the culture medium result in the formation of a protein corona around the NPs, stabilizing their dispersion, which can be used for in vitro cellular studies. The identification of the optimal stirring time is crucial for achieving dispersion and stability. This is assessed through a comprehensive stability testing protocol employing dynamic light scattering to evaluate the particle size distribution stability and polydispersity. Additionally, the effective density of the NPs is obtained for the stable NP dispersions using the volumetric centrifugation method, while cellular dosimetry calculations are done using available cellular computational modeling, mirroring approaches used for hydrophilic NPs. The robustness of the proposed dispersion approach is showcased using a highly hydrophobic NP model (black carbon NPs) and two culture media, RPMI medium and SABM, that are widely used in cellular studies. The proposed approach for the dispersion of hydrophobic NPs results in stable dispersions in both culture media used here. The NP effective density of 1.03–1.07 g/cm3 measured here for black carbon NPs is close to the culture media density, resulting in slow deposition on the cells over time. So, the present methodology for dispersion and dosimetry of hydrophobic NPs is essential for the design of dose–response studies and overcoming the challenges imposed by slow particle deposition. [ABSTRACT FROM AUTHOR]

Tremendous efforts have been made to construct large-scale estimates of aerosol components. However, Black Carbon (BC) estimates over large spatiotemporal scales are still limited. We proposed a novel approach utilizing machine-learning techniques to estimate BC on a large scale. We leveraged a comprehensive gridded BC emission database and auxiliary variables as inputs to train various machine learning (ML) models, specifically a Random Forest (RF) algorithm, to estimate high spatiotemporal BC concentration over China. Different ML algorithms have been applied to a large number of potential datasets and detailed variable importance and sensitivity analysis have also been carried out to explore the physical relevance of variables on the BC estimation model. RF algorithm showed the best performance compared with other ML models. Good predictive performance was observed for the training cases (R2 = 0.78, RMSE = 1.37 μgm−3) and test case databases (R2 = 0.77, RMSE = 1.35 μgm−3) on a daily time scale, illustrating a significant improvement compared to previous studies with remote sensing and chemical transport models. The seasonal variation of BC distributions was also evaluated, with the best performance observed in spring and summer (R2 ≈ 0.7–0.76, RMSE ≈ 0.98–1.26 μgm−3), followed by autumn and winter (R2 ≈ 0.7–0.72, RMSE ≈ 1.37–1.63 μgm−3). Variable importance and sensitivity analysis illustrated that the BC emission inventories and meteorology showed the highest importance in estimating BC concentration (R2 = 0.73, RMSE = 1.88 μgm−3). At the same time, albedo data and some land cover type variables were also helpful in improving the model performance. We demonstrated that the emission-based ML model with an appropriate auxiliary database (e.g., satellite and reanalysis datasets) could effectively estimate the spatiotemporal BC concentrations at a large scale. In addition, the promising results obtained through this approach highlight its potential to be utilized for the assessment of other primary pollutants in the future. [ABSTRACT FROM AUTHOR]

Short-term exposure to ultra-fine Black Carbon (BC) particles produced during incomplete fuel combustion of wood and fossil fuel has been linked to respiratory and cardiovascular diseases, hospitalizations and premature deaths. The goal of this research was to assess traffic-related BC in a cold climate along an urban highway and 300 m into an adjacent residential neighborhood. BC was measured with an aethalometer (MA350, Aethlabs) along the main traffic artery in geothermally heated Reykjavík, the capital of Iceland (64.135° N–21.895° W, 230,000 inhabitants). Stationary monitoring confirmed that traffic was the dominant source of roadside BC in winter, averaging 1.0 ± 1.1 µg/m3 (0.6 and 1.1 µg/m3 median and interquartile range; 28,000 vehicles/day). Inter-day variations in BC were primarily correlated to the atmospheric lapse rate and wind speed, both during stationary and mobile campaigns. During winter stills, BC levels surpassed 10 µg/m3 at intersections and built up to 5 µg/m3 during the afternoon in the residential neighborhood (adjacent to the highway with 43,000 vehicles/day). The BC penetrated deeply into the neighborhood, where the lowest concentration was 1.8 µg/m3 within 300 m. BC concentration was highly correlated to nitrogen dioxide (r > 0.8) monitored at the local Urban Traffic Monitoring site. [ABSTRACT FROM AUTHOR]

The effects of heavy fuel oil and biodiesel blends on engine combustion and emissions were studied in a marine two-stroke diesel engine. The engine was operated under propeller conditions using five different fuels with biodiesel blends of 10% (B10), 30% (B30), 50% (B50), and sulphur contents of 0.467% low sulphur fuel oil (LSFO) and 2.9% high sulphur fuel oil (HSFO). Tests have shown that using a biodiesel blend increases the engine fuel consumption due to its lower calorific value. Heavy fuel oil has a high Polycyclic aromatic hydrocarbons (PAH) content, which leads to higher exhaust temperatures due to severe afterburning in the engine. A comparison of engine soot emissions under different fuel conditions was carried out, and it was found that the oxygen content in biodiesel promoted the oxidation of soot particles during the combustion process, which reduced the soot emissions of biodiesel. Compared to HSFO, B10, B30, B50 and LSFO, the soot emission concentrations were reduced by 50.2%, 56.4%, 61% and 37.4%, respectively. In our experiments, the soot particles in the engine exhaust were sampled with a thermal float probe. Using Raman spectroscopy analysis, it was found that as the biodiesel ratio increased, the degree of carbonisation of the soot particles in the exhaust became less than that in the oxygenation process, resulting in a decrease in the degree of graphitisation. [ABSTRACT FROM AUTHOR]

Black carbon (BC) aerosols are important for absorbing aerosols, affecting global climate change and regional air quality, and potentially harming human health. From March to May 2023, we investigated black carbon aerosol levels and air pollution in Beijing. Employing methods such as linear regression, Potential Source Contribution Function (PSCF) and Concentration-Weighted Trajectory (CWT), we analyzed the characteristics and sources of black carbon aerosols in the region. Results indicate that the light absorption coefficients of BC and BrC decrease with increasing wavelength, with BrC accounting for less than 40% at 370 nm. Daily variations in BC and PM2.5 concentrations exhibit similar trends, peaking in March, and BC displays a distinct bimodal hourly concentration structure during this period. Aethalometer model results suggest that liquid fuel combustion contributes significantly to black carbon (1.08 ± 0.71 μg·m−3), surpassing the contribution from solid fuel combustion (0.31 ± 0.2 μg·m−3). Furthermore, the significant positive correlation between BC and CO suggests that BC emissions in Beijing predominantly result from liquid fuel combustion. Potential source area analysis indicates that air masses of spring in Beijing mainly originate from the northwest (40.93%), while potential source areas for BC are predominantly distributed in the Beijing–Tianjin–Hebei region, as well as parts of the Shandong, Shanxi and Henan provinces. Moreover, this study reveals that dust processes during spring in Beijing have a limited impact on black carbon concentrations. This study's findings support controlling pollution in Beijing and improving regional air quality. [ABSTRACT FROM AUTHOR]

Background: Airborne environmental and engineered nanoparticles (NPs) are inhaled and deposited in the respiratory system. The inhaled dose of such NPs and their deposition location in the lung determines their impact on health. When calculating NP deposition using particle inhalation models, a common approach is to use the bulk material density, ρb, rather than the effective density, ρeff. This neglects though the porous agglomerate structure of NPs and may result in a significant error of their lung-deposited dose and location. Results: Here, the deposition of various environmental NPs (aircraft and diesel black carbon, wood smoke) and engineered NPs (silica, zirconia) in the respiratory system of humans and mice is calculated using the Multiple-Path Particle Dosimetry model accounting for their realistic structure and effective density. This is done by measuring the NP ρeff which was found to be up to one order of magnitude smaller than ρb. Accounting for the realistic ρeff of NPs reduces their deposited mass in the pulmonary region of the respiratory system up to a factor of two in both human and mouse models. Neglecting the ρeff of NPs does not alter significantly the distribution of the deposited mass fractions in the human or mouse respiratory tract that are obtained by normalizing the mass deposited at the head, tracheobronchial and pulmonary regions by the total deposited mass. Finally, the total deposited mass fraction derived this way is in excellent agreement with those measured in human studies for diesel black carbon. Conclusions: The doses of inhaled NPs are overestimated by inhalation particle deposition models when the ρb is used instead of the real-world effective density which can vary significantly due to the porous agglomerate structure of NPs. So the use of realistic ρeff, which can be measured as described here, is essential to determine the lung deposition and dosimetry of inhaled NPs and their impact on public health. [ABSTRACT FROM AUTHOR]

Emissions from biomass burning challenge efforts to curb air pollution in cities downwind of fire-prone regions, as they contribute large amounts of brown carbon (BrC) and black carbon (BC) particles. We investigated the patterns of BrC and BC concentrations using Aethalometer data (at λ = 370 and 880 nm, respectively) spanning four years at a site impacted by the outflow of smoke. The data required to be post processed for the shadowing effect since, without correction, concentrations would be between 29% and 35% underestimated. The BrC concentrations were consistently higher than the BC concentrations, indicating the prevalence of aerosols from biomass burning. The results were supported by the Ångström coefficient (Å 370/880), with values predominantly larger than 1 (mean ± standard deviation: 1.25 ± 0.31). Å 370/880 values below 1 were more prevalent during the wet season, which suggests a contribution from fossil fuel combustion. We observed sharp BrC and BC seasonal signals, with mean minimum concentrations of 0.40 µg/m3 and 0.36 µg/m3, respectively, in the wet season, and mean maximum concentrations of 2.05 µg/m3 and 1.53 µg/m3 in the dry season. The largest concentrations were observed when northerly air masses moved over regions with a high density of fire spots. Local burning of residential solid waste and industrial combustion caused extreme BrC and BC concentrations under favourable wind directions. Although neither pollutant is included in any ambient air quality standards, our results suggest that transboundary smoke may hamper efforts to meet the World Health Organization guidelines for fine particles. [ABSTRACT FROM AUTHOR]

Black carbon (BC) or soot contains ultrafine combustion particles that are associated with a wide range of health impacts, leading to respiratory and cardiovascular diseases. Both long-term and short-term health impacts of BC have been documented, with even low-level exposures to BC resulting in negative health outcomes for vulnerable groups. Two aethalometers—AethLabs MA350 and Aerosol Magee Scientific AE33—were co-located at a Utah Division of Air Quality site in Bountiful, Utah for just under a year. The aethalometer comparison showed a close relationship between instruments for IR BC, Blue BC, and fossil fuel source-specific BC estimates. The biomass source-specific BC estimates were markedly different between instruments at the minute and hour scale but became more similar and perhaps less-affected by high-leverage outliers at the daily time scale. The greater inter-device difference for biomass BC may have been confounded by very low biomass-specific BC concentrations during the study period. These findings at a mountainous, high-elevation, Greater Salt Lake City Area site support previous study results and broaden the body of evidence validating the performance of the MA350. [ABSTRACT FROM AUTHOR]

Estuarine processes regulate the transport of dissolved black carbon (DBC) and associated contaminants to the ocean. However, there is limited understanding of the geochemical behavior of DBC in estuaries. In this study, DBC in the Pearl River Estuary (PRE) and the northern shelf of the South China Sea were examined using the benzene polycarboxylic acid (BPCA) method. DBC, bulk dissolved organic carbon (DOC), and chromophoric dissolved organic matter (CDOM) exhibited distinct behaviors during their transport from the PRE to the sea. DOC and CDOM decreased during the initial mixing of river water and seawater but increased at the lower PRE. In contrast, high aromaticity DBC inputs were observed throughout the PRE, likely originating from local terrestrial sources, such as runoff from nearby islands, as indicated by the high RH/L values (i.e., the ratio of BPCA containing 5 and 6 carboxyl groups to that containing 3 and 4 carboxyl groups; 2.03–2.30). In the Pearl River-plume zone (salinity < 33.0), DOC, CDOM, and DBC showed quasi-conservative behaviors against salinity, indicating that their geochemical behaviors were primarily governed by physical mixing between plume water and seawater. Using a flux model, it was estimated that the discharge of riverine DBC from the Pearl River Delta ranged from 11.2 to 16.3 Gg year−1, representing an important source of bio-resistant DOC to the northern South China Sea. [ABSTRACT FROM AUTHOR]

Purpose: Black carbon (BC) is a crucial component of organic carbon (OC), forming due to incomplete combustion of fossil fuels and biomass. Identifying the distribution characteristics and possible sources of BC is essential for managing carbonaceous pollution in freshwater lakes, especially in a mining and metallurgy region, where the metallurgical activities poses a significant threat to the aquatic ecological environment. This study examined the distribution characteristics and potential sources of BC in surface sediments from three distinct development areas. Materials and methods: In January 2019, 32 surface sediment samples were collected, including 17 from Wang Lake (WL), five from Lianhua Lake (LL), and 10 from Mati Lake (ML). The BC measurements were conducted using the thermal-optical reflectance (TOR) method with quality control. Additionally, empty silver capsules were thermally treated and acidified as blank controls. Statistical analyses, correlation analyses, BC/OC ratios, and char/soot ratios were employed to examine the spatial distribution and potential sources of BC in the different lakes. Results and discussion: The measured BC concentrations were 0.722 ± 0.339, 1.99 ± 1.90 and 0.748 ± 0.313 mg g−1 in WL, LL, and ML, respectively. Spatial analysis revealed elevated BC levels in LL, WL, and specific areas within WL. The char/soot ratios exhibited variability, with lower ratios in LL, higher ratios in ML, and variable ratios in WL. Correlation analysis and the relationship between BC/OC ratios and char/soot ratios indicated the influence of local biomass combustion deposition on BC accumulation in lake sediments. Furthermore, by comparing BC/OC ratios and char/soot ratios with local developmental characteristics, contributions from vehicular emissions and coal combustion deposition were observed in LL. The leakage of fossil fuels from boats may also contribute to the accumulation of carbon compounds in WL. Long-term metallurgical-related activities involving various sources of energy burning may account for the BC accumulation in ML, located in an industrial area. Conclusions: Human activities significantly influenced the distribution and sources of BC in sediments from different types of lakes in areas with diverse developmental characteristics. These findings provide valuable insights for researchers and government authorities to understand the main contributions of BC to sediment and develop targeted policies for preventing and controlling carbonaceous pollution based on the unique developmental characteristics in similar mining areas worldwide. [ABSTRACT FROM AUTHOR]

Tibetan Plateau (TP) is known as the water tower of Asia, and glaciers are solid reservoirs that can regulate the amount of water. Black carbon (BC), as one of the important factors accelerating glacier melting, is causing evident environmental effects in snow and ice. However, a systematical summary of the potential sources, analytical methods, distributions, and environmental effects of BC in snow and ice on the TP's glaciers is scarce. Therefore, this study drew upon existing research on snow and ice BC on glaciers of the TP to describe the detection methods and uncertainties associated with them to clarify the concentrations of BC in snow and ice and their climatic effects. The primary detection methods are the optical method, the thermal–optical method, the thermochemical method, and the single-particle soot photometer method. However, few studies have systematically compared the results of BC and this study found that concentrations of BC in different types of snow and ice varied by 1–3 orders of magnitude, which drastically affected the regional hydrologic process by potentially accelerating the ablation of glaciers by approximately 15% and reducing the duration of snow accumulation by 3–4 days. In general, results obtained from the various testing methods differ drastically, which limited the systematical discussion. Accordingly, a universal standard for the sampling and measurement should be considered in the future work, which will be beneficial to facilitate the comparison of the spatiotemporal features and to provide scientific data for the model-simulated climatic effects of BC. [ABSTRACT FROM AUTHOR]

Black carbon (BC) emissions from shipboard diesel engines are the next potentially important issue of interest to the International Maritime Organization (IMO) and are considered to have a significant impact on the climate environment and human health. However, theories and technologies regarding the mechanisms of black carbon formation, oxidizing and influencing factors, emission detection methods, and abatement techniques are still missing in science and engineering. This paper provides a comprehensive overview of relevant advances in international maritime regulations, the frontier theory on formation mechanisms, comprehensive physical and chemical properties, and the potential reduction measures and control measures of emissions. These results suggest that BC is produced in the combustion flame of fuel and is related to the nucleation as well as the formation of PAHs. It helps to understand the initial generation process of black carbon and reduce its emission by studying it in detail and revealing some key factors, including micromorphology, nanostructural features, surface functional groups, oxidizing activity, size distribution, and elemental composition. Further, an in-depth understanding of the complex characteristics of BC can also help to identify viable BC measurement techniques and instrumentation for marine engines, thereby enhancing emission regulation. Overall, extensive technology can reduce BC emissions from marine diesel engines by approximately 50%. The information contained in this report can be used as a significant reference to further explore the BC formation mechanism and develop exclusive BC emission control strategies. [ABSTRACT FROM AUTHOR]

Aethalometer is a widely used instrument for black carbon (BC) mass concentration and light absorption coefficient (babs) measurements around the world. However, field intercomparison of the two popular models, dual-spot (AE33) and single-spot (AE31) aethalometers, remain limited; in addition, the difference in secondary brown carbon (BrCsec) light absorption estimation between the two models is largely unknown. We performed full-year collocated AE33 and AE31 measurements in a megacity in southern China – Guangzhou. The babs values agree well between the two aethalometers (R² > 0.95), with AE33/AE31 slopes ranging from 0.87 to 1.04 for 7 wavelengths. AE33 consistently exhibits lower limits of detection (LOD) than AE31 for time resolutions of 2 to 60 min. The AE33/AE31 slope for equivalent BC (eBC) was 1.2, implying the need for site-specific post-correction. The Ångström exponent (AAE) obtained from different approaches agrees not very well between the two models, with the biggest discrepancy found in AAE880/950. The estimated BrCsec light absorption at 370 nm (babs370_BrCsec) was calculated using the minimum R squared method (MRS) for both Aethalometers. The babs370_BrCsec comparison yields a slope of 0.78 and an R² of 0.72 between the two models, implying a non-negligible inter-instrument difference. This study highlights the high consistency in babs but less so in AAE between AE31 and AE33, and reveals site-specific correction for eBC estimation and non-negligible difference in BrCsec estimation. The results are valuable for data continuity in long-term aethalometer measurements when transiting from the older (AE31) to the newer (AE33) model, as anticipated in permanent global-climate and air-quality stations. [ABSTRACT FROM AUTHOR]

Black carbon (BC) is the strongest visible-light-absorbing aerosol component in the atmosphere, with a significant impact on Earth’s radiative budget. Accurate measurement of BC light absorption is crucial for estimating its radiative effect. The micro-aethalometer model 200 (MA200) by AethLabs, USA, offers high-time-resolution measurement of the multi-wavelength absorption coefficient (σab) within 1 s, making it widely used in aerial measurement due to its compact size and light weight. However, the reliability of the measured σab has not been extensively studied in previous research. In this study, we evaluate the performance of MA200 by comparing σab measurements obtained from MA200 with those from the aethalometer model 33 (AE33) by Magee, USA. Our results revealed a significant variation in the determinant coefficient (R²) between σab measurements from MA200 and AE33, depending on the time resolution. The R² increases from 0.1 to 0.5 and further to 0.97 as the time resolution of σab increases from 1 s to 30 s and 60 s, respectively. We recommend a minimum time resolution of 30 s for stable σab measurements using MA200. Moreover, we determine σab from attenuation coefficient (σATN) measured by MA200 as σab = (σATN – σ0)/CMA, where σ0 ranges from – 15.3 Mm–1 to – 6.4 Mm–1 and CMA ranges from 2.65 to 3.21. Correcting the measured σab based on the findings of this study can provide reliable results for estimating the radiative effects of BC. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

Black Carbon (BC), the second-largest contributor to global warming, has detrimental effects on human health and the environment. However, the accurate quantification of BC poses a significant challenge, impeding the comprehensive assessment of its impacts. Therefore, this paper aims to critically review three quantitative methods for measuring BC: Thermal Optical Analysis (TOA), the Optical Method, and Laser-Induced Incandescence (LII). The determination principles, available commercial instruments, sources of deviation, and correction approaches associated with these techniques are systematically discussed. By synthesizing and comparing the quantitative results reported in previous studies, this paper aims to elucidate the underlying relationships and fundamental disparities among Elemental Carbon (EC), Equivalent Black Carbon (eBC), and Refractory Black Carbon (rBC). Finally, based on the current advancements in BC quantification, recommendations are proposed to guide future research directions. [ABSTRACT FROM AUTHOR]

Efficient and accurate computation of the single‐scattering properties of black carbon (BC) aerosols is fundamental in various fields, including remote sensing and climate simulations. In this study, we developed a composite model of fractal aggregates of BC encapsulated with hygroscopic aerosols to represent the ambient BC. We used the invariant imbedding T‐matrix method to compute the optical properties of fully and partially encapsulated BC aerosols. In this new model, the traditional assumption of unoverlapped surfaces in the super‐position T‐matrix method is unnecessary. After extensive simulations, we established a database of single‐scattering properties, including the extinction efficiency, the single‐scattering albedo, the asymmetry factor and six phase matrix elements. Moreover, we obtained deep neural networks (DNNs) from this database using a deep learning method. These DNN models provide a universal interface for predicting the optical properties of ambient BC aerosols. Specifically, through a modified architecture of the DNN, we trained two models based on the database to predict three integrated optical properties (extinction efficiency, single‐scattering albedo, and asymmetry factor) and six phase matrix elements. We performed statistical assessments based on the true values in the database and the predicted values from the DNNs, demonstrating that the DNNs accurately predicted all single‐scattering properties. Therefore, the developed DNN models can be conveniently implemented in aerosol optical parameterization for remote sensing studies and atmospheric models. Plain Language Summary: Black carbon (BC) aerosol plays a significant role in the atmosphere, influencing climate through its interactions with radiation, such as scattering and absorbing. The accurate determination of the single‐scattering properties of BC, including the extinction efficiency, the single‐scattering albedo, the asymmetry factor and six phase matrix elements, is crucial for understanding its radiation effects. In this study, we developed a comprehensive model for BC particles that incorporates complex morphological characteristics and the mixing of BC with other hygroscopic aerosols. We established a database of single‐scattering properties for these models using the invariant imbedding T‐matrix method. However, the large storage space required by this database (over 20 GB) makes it impractical for widespread applications. Therefore, we employed a deep learning method to compress the storage consumption. Two deep neural networks (DNNs) were trained using the database, enabling the prediction of all single‐scattering properties. Remarkably, the performance of the DNNs was excellent, with a coefficient of determination greater than 0.99 for all single‐scattering properties, as determined through statistical assessment. These DNN models hold great potential for various atmospheric radiation and remote sensing studies in the future. Key Points: A flexible model of partially and fully encapsulated fractal black carbon particles was developedA database of single‐scattering properties of encapsulated fractal black carbon particles was constructedTwo deep neural networks were obtained, offering a flexible approach to calculating the optical properties of black carbon aerosols [ABSTRACT FROM AUTHOR]

Black Carbon (BC) is an important atmospheric pollutant, well recognized for adverse health and climatic effects. The present work discusses the monthly and seasonal variations of BC sources, health risks, and light absorption properties. The measurement was done from January to December 2021 using a seven wavelength aethalometer. Annual average BC concentration during the study period was 12.2 ± 8.8 μg/m3 (ranged from 1.9 – 52.2 μg/m3). Results represent highest BC concentration during winter (W), followed by post-monsoon (P-M), summer (S), and monsoon (M) seasons where the fossil fuel (FF) combustion is the major source during W, S, and M seasons and biomass burning (BB) during the P-M season. The health risk assessment revealed that individuals in Delhi are exposed to BC levels equivalent to inhaling the smoke from 36 passively smoked cigarettes (PSC) everyday. The risk is highest during W reaching upto 71 PSC and minimum during M i.e., 9 PSC. The light absorption properties were calculated for BC (AbsBC) and Brown carbon (AbsBrC). AbsBC and varied from 229–89 Mm−1 between 370–950 nm and AbsBrC varied from 87–12 Mm−1 between 370–660 nm. AbsBC contributed substantially to total absorption at all wavelengths, while AbsBrC contribution is quite significant in the UV region only. Trajectory analysis confirmed significant influence of regional sources (e.g., biomass-burning aerosols from northwest and east direction) on air quality, health risks, and light absorption properties of BC over Delhi especially during the P-M season. The BB events of Punjab, Haryana, Uttar Pradesh, and eastern Pakistan seems to have significant influence on Delhi's air quality predominantly during P-M season. [ABSTRACT FROM AUTHOR]

This work is part of a study on the impact of black carbon (BC) transfer from various sources to the Arctic on climate change in the region. The main objectives are to develop software for analyzing the Lagrangian transport of air particles; assessing the deposition of aerosol particles by precipitation and the concentration of particles in the atmosphere; and obtaining, for specific conditions of atmospheric circulation during severe fires in the years of maximum reduction in the Arctic sea ice area, estimates of the relative residence time of air particles emitted by these fires over the Arctic Basin (AB), as well as the proportion of BC deposited in the AB from fires. This software package contains a module for calculating Lagrangian trajectories from a 4-dimensional wind array (u, v, ω, t), which contains horizontal wind components and an analog of vertical speed available from reanalysis, as well as modules for the postprocessing of the found trajectories, which allow us to obtain in a given area the residence time estimates, 3-dimensional BC concentration, and BC deposition on the surface, also using reanalysis data and some empirical constants. Since the main decrease in the Arctic sea ice area occurred in 2 years, 2007 and 2012, it was supposed to analyze the fires of these years; however, in 2007, there were no great fires, and in 2012 one fire was much larger than the others (K-217, March–June). This fire was chosen for the experiments: several sets of trajectories were obtained for it, corresponding to various options for choosing the initial conditions, and estimates were obtained for the fraction of trajectories that passed over the Arctic basin, the time spent there, and the fraction of BC deposited in the AB. Together, these estimates led to the conclusion that Siberian fires can hardly be the leading cause of the accelerated melting of Arctic sea ice. [ABSTRACT FROM AUTHOR]

In this study, we concurrently determined the combined ratio of black carbon (BC) and carbon monoxide (CO) in two distinct cities in eastern India: Jamshedpur (JSR) and Kharagpur (KGP). The investigation spanned from October 2019 to January 2020, revealing BC mass concentrations of 10.06 (± 1.59) µg m−3 in JSR and 5.49 (± 1.15) µg m−3 in KGP. Additionally, the average CO concentrations measured were approximately 913.63 (± 217.85) ppbv in JSR and 507.31 (± 125.06) ppbv in KGP. Analysis of GIOVANNI NASA satellite data highlighted elevated concentrations of BC and CO in the Indo-Gangetic Plain (IGP), the foothills of the central Himalayas, and the eastern region of India. Utilizing diagnostic ratio analysis to attribute the sources of BC, we found that wood-burning contributed more significantly to the BC levels in KGP compared to JSR. The higher overall aerosol concentration in JSR was attributed to the prevalence of numerous industries and heavy traffic. Pearson correlation analysis indicated substantial correlations between BC–CO and BC–PM2.5, with correlation coefficients of r2 = 0.65 and r2 > 0.96, respectively. These results underscore the need for significant changes to be implemented, such as transitioning to alternative appliances that do not rely on fossil fuels. By adopting cleaner and more sustainable energy sources, we can effectively mitigate the adverse impacts of BC, PM2.5, and CO emissions on air quality and public health. Air back-trajectory analysis unveiled the predominant northward transmission of pollution from northern India. Additionally, air masses originating from neighboring countries such as Pakistan, Nepal, Bangladesh, and Bhutan also contributed to the pollution levels. Health risk assessments revealed estimated non-cancerous particulate health risks (Npsc) ranging from 6.27 to 25.6 in JSR and 2.02 to 8.28 in KGP, emphasizing potential health implications associated with BC exposure in the two cities. [ABSTRACT FROM AUTHOR]

Lake sediments are unique archives of human environment interactions. Lake Prespa is one of the oldest lakes in Europe, lying in the southwestern Balkans and thus on a possible dispersal route of anatomically modern humans from Africa. In this study, we investigated the effects of climate, vegetation and human activity on fire over the last 92,000 years in this region. Sediment samples were taken from Lake Prespa, and nearby Lake Ohrid for comparison of the regional relevance, and analyzed for benzene polycarboxylic acids as markers for burned organic carbon residues (black carbon, BC). Peaking contents of BC (up to 1 g BC kg−1 sediment) coincided with warm and humid phases, when forests expanded at marine isotope stages (MIS) 5 and 1. During the colder and more arid climates of MIS 4 and 2, BC contents were lowered by a factor of 10, with a distinct minimum during the Last Glacial Maximum (0.07 g BC kg−1). The ratio of pentacarboxylic acid to mellitic acid (B5CA/B6CA) declined from 1.2 at MIS 5 to values of 0.3 at MIS 2, confirming a change in fire regime. Overall, BC contents peaked at cycles of solar radiation, vegetation composition and fuel availability, and thus correspond to the BC signal of other environmental archives. However, in the Late Holocene and as a result of human sedentary settlement, BC production increased, independent of decreasing insolation forcing. Key Points: First black carbon record of the Dessarate (Ohrid‐Prespa) Lake regionFire activity over the past 92,000 years has been highest during periods of warm/humid climate and forest vegetation [ABSTRACT FROM AUTHOR]

In this study, the temporal variations of black carbon (BC) were analyzed from November 2019 to September 2021, in Tacna, Peru. Ground measurements obtained with a photoacoustic extinctiometer (PAX BC) and NASA's MERRA-2 reanalysis data (MERRA-2 BC) were used. The seasonal concentrations of PAX BC (mean ± standard deviation) were as follows: 0.70 ± 0.35, 0.73 ± 0.46, 0.70 ± 0.39, and 0.85 ± 0.46 µg m−3, for spring, summer, autumn, and winter, respectively; while MERRA-2 BC values were 0.12 ± 0.11, 0.06 ± 0.02, 0.06 ± 0.02, and 0.11 ± 0.06 µg m−3, for the same seasons. We found a large discrepancy between these two techniques, as the PAX BC measurements were an order of magnitude higher than the MERRA-2 BC values. In addition, MERRA-2 did not record urban pollution events and did not present the BC weekend effect. The most frequent wind direction (81%) was from the southwest and the sources of greatest contamination were located to the northeast and southeast. The Mann–Kendall test confirmed a downward trend in PAX BC one week (37%) and two weeks (30%) after the start of the COVID-19 lockdown, and no trend in MERRA-2 BC. These results suggest that MERRA-2 underestimates the BC emissions from local sources. [ABSTRACT FROM AUTHOR]

Black carbon (BC) is a significant component of fine particulate matter (PM2.5, with aerodynamic diameters ≤ 2.5 μm), and its spatial distribution greatly affects the global radiation budget. However, the vertical distributions and key driving factors of BC in the atmospheric boundary layer, where BC is mostly concentrated, remain unclear. In this study, gradient measurements of BC were made using an unmanned aerial vehicle (UAV) platform from ground level to 500 m above ground level (AGL) during and after the 2016 G20 control period in Shanghai. Generally, vertical profiles of BC from local time (LT) 9 to 17 on all experimental days demonstrated an upward trend with increasing height. The BC emitted from chimneys was initially released at higher altitudes, resulting in the positive gradients of vertical BC profiles. Furthermore, with the progressive development of the boundary layer height from LT 9 to 15, the average concentration of BC per vertical profile decreased. However, meteorological conditions unfavorable for dispersions caused by particularly high temperatures, low wind speed, unfavorable boundary layer conditions, or especially high relative humidity, and hygroscopic growth owing to the extremely high relative humidity, led to an overall increase in vertical BC and ground-based PM2.5 and BC. Despite the impact of adverse meteorological conditions, emission control measures during the control period not only effectively decreased the BC concentration but also reduced the proportion of BC in PM2.5 in the atmospheric boundary layer. The results of this study can provide valuable observations for evaluating numerical model results and important implications for making control strategies of BC in the future. [ABSTRACT FROM AUTHOR]

Atmospheric black carbon (BC) aerosols have been long‐lasting uncertain components in environmental and climate studies. Global climate models (GCMs) potentially overestimate BC absorption efficiency due to a lack of consideration of complex BC microphysical and mixing properties. We extract multiple BC properties from observations and develop an aerosol optical module known as Advanced Black Carbon (ABC) in the framework of the Modal Aerosol Model version 4 (MAM4). The ABC module is implemented in the Community Atmosphere Model version 6 (CAM6) and evaluated by in situ and remote sensing observations. CAM6‐ABC addresses the shortcomings of CAM6‐MAM4 in terms of BC microphysical and mixing properties, particularly their size, mixing state and optical simulations. Sensitivity simulations show that the global BC absorption aerosol optical depth at 550 nm simulated by CAM6‐ABC is reduced by ∼29% compared with that in CAM6‐MAM4. The BC absorption enhancement simulated by CAM6‐ABC is reduced from ∼2.6 of the default MAM4 to ∼1.4, which is closer to the observed values (mostly less than 1.5). With improved BC absorption estimation, the biases of aerosol single‐scattering coalbedo simulations are reduced by 18%–69% compared with global Aerosol Robotic Network observations. Moreover, the globally averaged BC direct radiative effect is reduced from 0.37 to 0.28 W/m2 at the top of the atmosphere. Our new scheme alleviates the overestimation of BC absorption in GCMs by constraining BC microphysical and mixing properties when assessing aerosol radiative and climate effects, and it can be easily implemented in most modal‐based aerosol modules of climate models. Plain Language Summary: As a climate warming agent in the atmosphere, black carbon (BC) aerosols remain largely uncertain in their light absorption. In global climate models (GCMs), the BC absorption efficiency tends to be overestimated due to insufficient consideration of the BC microphysical properties and mixing state. Our work quantifies the aerosol representation deficiency in GCMs due to the microphysical and optical properties and compensates for this deficiency in our improved BC and aerosol optical property representation. In this study, we analyze and summarize the key BC properties that highly influence their radiative effects based on multisource observations, for example, size distribution and mixing state, develop an improved aerosol optical module to better account for those observations, and implement this representation in a GCM. We use in situ observations to evaluate our module with improved BC and aerosol optical property representations. The results show that the overestimated BC absorption is much closer to the observations due to a more accurate representation of BC‐related microphysical and mixing properties. Correspondingly, our improved BC representation weakens the modeled BC radiative and climate effects by as much as ∼24%. Key Points: Observations of black carbon (BC) properties are implemented in the current aerosol optical module of Community Atmosphere Model version 6The modeled BC absorption enhancement and aerosol bulk optical properties are closer to the observationsThe BC top of the atmosphere direct radiative effect decreases from 0.37 to 0.28 W/m2 [ABSTRACT FROM AUTHOR]

Wildfire emission inventories are usually applied with biome‐scale emission factors for atmospheric modeling. However, emission factors measured for different plant species vary substantially within the same biome. We apply the species‐specific emission factors and refine the Fire Emission Inventory‐northern Eurasia (FEI‐NE), and derive the wildfire black carbon emission inventory in northern Eurasia from 2002 to 2015. Our new inventory produces 61% more black carbon emissions than current estimates based on Global Fire Emission Database (GFED) and 33% less than FEI‐NE. Model simulations with different inventories are compared with ground‐based and satellite retrievals of aerosol absorption optical depth (AAOD). Compared with the Ozone Monitoring Instrument, the normalized root mean square deviation of AAOD over northern Eurasia is reduced from 1.0 under FEI‐NE to 0.95 through application of the new inventory. This study reveals the importance of applying sub‐biome‐scale emission factors for wildfire inventories development and revisiting emissions uncertainty in atmospheric modeling. Plain Language Summary: A recent biomass burning emission inventory for black carbon in northern Eurasia was developed as FEI‐NE. We found that the emission factors applied for wildfires in northern Eurasia boreal forest and grassland were adopted from the prescribed fire measurements conducted in the United States for woody savannas and wetlands, respectively. By comparing with recently published local measurements in Siberia, we mapped the emission factors for plant species from the database published by U.S. Forest Service to biomass structures in northern Eurasia and rebuilt the FEI‐NE inventory as FEI‐NEsp. Modeling results obtained from GEOS‐Chem for 2011–2012 suggested that the simulation with FEI‐NEsp agreed better with ground‐based and satellite observations than FEI‐NE and GFEDv4.1s. Key Points: Emission factors indexed by plant species are used to replace biome‐scale factors to update fire emission inventory over northern EurasiaUpdated fire emission for black carbon over northern Eurasia is 33% lower than the original inventory FEI‐NE, but 61% higher than GFEDSimulation with the new inventory shows better reproduced ground‐based and satellite retrievals of aerosol absorption optical depth [ABSTRACT FROM AUTHOR]

• Online OC and BC were measured by a newly developed TCA08 coupled with an AE33. • The annual average f biomass to BC was 27.1% but in winter it increased to 41.6%. • BrC contribute 30.8% to total absorption coefficient with winter maximum of 44.2%. • High AAE 370-520 and MAC BrC , 370 in winter suggest more impact from biomass burning. To elucidate the variations in mass concentrations of organic carbon (OC) and black carbon (BC) in PM 2.5 and their light absorption characteristics in Lanzhou, we conducted one-year online measurements by using a newly developed total carbon analyzer (TCA08) coupled with an aethalometer (AE33) from July 2018 to July 2019. The mean OC and BC concentrations were 6.4 ± 4.4 and 2.0 ± 1.3 µg/m3, respectively. Clear seasonal variations were observed for both components, with winter having the highest concentrations, followed by autumn, spring, and summer. The diurnal variations of OC and BC concentrations were similar throughout the year, with daily two peaks occurring in the morning and evening, respectively. A relatively low OC/BC ratio (3.3 ± 1.2, n = 345) were observed, indicating that fossil fuel combustion was the primary source of the carbonaceous components. This is further substantiated by relatively low biomass burning contribution (f biomass : 27.1% ± 11.3%) to BC using aethalometer based measurement though f biomass value which increased significantly in winter (41.6% ± 5.7%). We estimated a considerable brown carbon (BrC) contribution to the total absorption coefficient (b abs) at 370 nm (yearly average of 30.8% ± 11.1%), with a winter maximum of 44.2% ± 4.1% and a summer minimum of 19.2% ± 4.2%. Calculation of the wavelength dependence of total b abs revealed an annual mean AAE 370-520 value of 4.2 ± 0.5, with slightly higher values in spring and winter. The mass absorption cross-section of BrC also exhibited higher values in winter, with an annual mean of 5.4 ± 1.9 m2/g, reflecting the impact of emissions from increased biomass burning on BrC concentrations. [ABSTRACT FROM AUTHOR]

Black carbon (BC), an important component of atmospheric aerosol, plays a significant role in regional climate, hydrological cycle, variation of monsoon rainfall, and human health. The 40-year detailed atmospheric BC over China from 1981 to 2020 is systematically investigated through the MERRA-2 reanalysis dataset. MERRA-2 BC generally showed a good correlation (R = 0.68) compared with 673 monthly samples from ground-based observation at 35 stations around China. The overall annual average of MERRA-2 BC concentration over China is 1.15 μg/m3, with a fast growth rate during 1981–2007 and a relatively slow decrease after that. The winter season has the highest mean concentration of BC, followed by autumn and spring, whereas summer shows relatively weaker values. The order of annual average BC concentrations during 1981–2020 is Beijing-Tianjin-Hebei region (BTH, 4.02 μg/m3) > Sichuan Basin (SB, 3.94 μg/m3) > Yangtze River Delta (YRD, 2.68 μg/m3) > Pearl River Delta (PRD, 1.47 μg/m3). The monthly mean BC concentrations over the BTH, YRD, PRD and SB are estimated to be smallest 3.18 μg/m3 in May, 1.94 μg/m3 in August, 0.82 μg/m3 in July, 3.04 μg/m3 in June, respectively, whilst largest consistently in December with 5.09 μg/m3, 3.83 μg/m3, 2.12 μg/m3, and 5.41 μg/m3, respectively. Our study indicates the primary potential source areas for BC are concentrated in the research city and its surroundings. Beijing and Chengdu are more BC-polluted areas than Shanghai and Guangzhou. Long-distance, regional transfer from south BTH contributes importantly to BC pollution in Beijing under the influence of prevailing southerly winds. The geographical location of Chengdu causes the transport and accumulation of BC inside the SB. [ABSTRACT FROM AUTHOR]

The cyanobacterium Trichodesmium is responsible for approximately half of the ocean's nitrogen input through nitrogen fixation. Although it was first recorded near Australia in the 18th century, the knowledge of where and when large quantity of Trichodesmium around Australia could be found is still lacking. Here, using multi‐band satellite imagery acquired between 2012 and 2021, we fill this knowledge gap through the use of deep learning, designed to recognize both the spectral shapes of individual pixels and spatial morphology of surface aggregations (scums) of Trichodesmium. Trichodesmium scums were found nearly everywhere around Australia, with a cumulative footprint (i.e., where the 10‐year average density is >0.001‰) exceeding 4.6 million km2. Strong seasonality was found, with peak months between September and November. Furthermore, temperature, iron‐rich dust and black carbon aerosols, with the latter being a result of frequent bushfires, play major roles in determining the spatial distributions and seasonality of Trichodesmium. Plain Language Summary: Responsible for half of the ocean's nitrogen input through nitrogen fixation, the saltwater cyanobacterium Trichodesmium is ubiquitous in global tropical and subtropical oceans but particularly abundant around Australia. However, although the earliest report goes back to the 18th century, the knowledge of where and when large quantities of Trichodesmium can be found around Australia is still incomplete. Based on satellite imagery and deep learning, we quantified relative abundance of Trichodesmium around Australia for the period of 2012–2021. Surface aggregations of Trichodesmium were found almost everywhere except the southern coast, with a cumulative footprint exceeding 4.6 million km2. Strong seasonality was found, with peak months between September and November. The spatial distributions and seasonality were found to correlate well with water temperature, iron‐rich dust from Australian desert, and black carbon aerosols from frequent bushfires. With the projected ocean warming in the coming century, Trichodesmium may expand further south, making the cumulative footprint even larger. Key Points: Deep learning was applied to multi‐band satellite images to detect and quantify Trichodesmium surface scums around AustraliaTrichodesmium scums were found nearly everywhere around Australia with a seasonality and a cumulative footprint exceeding 4.6 million km2Distribution and seasonality of Trichodesmium were driven by temperature, iron‐rich dust and black carbon from the mainland bushfires [ABSTRACT FROM AUTHOR]

Refractive indices (RI) of particles are important in determining their radiative forcing. We measured optical coefficients of particles classified according to their aerodynamic diameter, allowing retrieval of RI using a Mie model. At 405 nm, the RI of BC from a diesel engine was 1.870 (±0.132) + 0.640 (±0.015) i. The RI of secondary organic aerosol (SOA), using α‐pinene and o‐cresol as precursors, were 1.584 ± 0.015 and 1.738 (±0.021) + 0.0316 (±0.0018) i, respectively. Neither SOAs demonstrated absorption at 660 nm and their RIs were 1.551 ± 0.011 and 1.586 ± 0.011, the similar value suggesting that a single RI may be sufficient for simulating the radiative forcing of SOA at this wavelength. In addition, organics were condensed onto BC to test optical models for coated particles. For BC particles coated with non‐absorbing organics, the extinction is predicted accurately by all models. The absorption is significantly over‐estimated by core‐shell, volume mixing, and effective medium approximations and under‐estimated by external mixing. For BC particles coated with weakly absorbing organics, the extinction and absorption are best described by external mixing when the coating ratio is less than 2.5. When the coating ratio is over 2.5, the difference between the external mixing predictions and measurements increases with the coating ratio. Our results show that the absorption of coated BC particles may not be predicted accurately based solely on the equivalent diameter, coating ratio, and pure component RIs, and considerations of additional factors such as morphology may be necessary. Plain Language Summary: Black carbon (BC) and brown carbon (BrC) are extensively investigated components of atmospheric aerosol due to their ability to absorb solar radiation and contribute to atmospheric heating, resulting in a positive radiative forcing. Although BC and BrC are very important for climate, they are poorly represented in atmospheric models. This is in part due to the lack of accurate refractive index (RI) descriptions for both BC and BrC. Previous studies have used mobility selection approaches to select BC/BrC particles upstream of optical spectroscopy instruments to allow RI characterizations, but these retrievals suffer from issues caused by multiple charging. We solved this issue by using a new aerosol classification technique, enabling optical measurements for an aerosol sample classified according to a single physical size without multiple charge artifacts, which improves the subsequent RI retrieval. In addition, non‐absorbing and weakly absorbing organic materials were condensed onto BC to form coated soot particles, allowing different optical models for mixed particles to be evaluated. We found that the absorption of coated BC particles may not be predicted with sufficient accuracy from knowledge of only the equivalent diameter, coating composition, and RI, and considering additional factors such as morphology may be necessary for accurate predictions. Key Points: Refractive indices of BC/BrC were derived without multiple charge artifactsA single RI may be sufficient for simulating the radiative forcing of secondary organic aerosol particles at the wavelength of 660 nmConsidering morphology may be necessary for accurate predictions of the absorption of coated BC particles [ABSTRACT FROM AUTHOR]

Radiative absorption of black carbon (BC) is of great importance in air quality and climate change. Simultaneous mitigation of haze pollution and climate warming requires an in‐depth understanding of haze‐BC‐climate connections based on direct observations. We simultaneously performed measurements in the North China Plain (NCP) and the Yangtze River Delta (YRD) during the winter of 2018–2019, when cross‐regional haze transport frequently occurred. We found that BC particles exhibited a thick coating thickness (100–120 nm) under haze pollution conditions in the NCP and were then transported to the YRD with regional haze development. BC particles in the downwind region showed a bimodal distribution of core‐size‐resolved aging degree, which can be used to separate and quantify local and regional BC. The results showed that the regional haze transport from the NCP brought 1–3 μg m−3 BC into the YRD. These regional BC particles exhibited ∼1.6 times stronger absorption efficiency than locally emitted BC. The direct radiative effects of BC in the downwind region were estimated to be enhanced by ∼2 times when regional haze pollution was transported from the NCP to the YRD. The amplification of BC's climate effect during regional haze pollution was attributed to the increases in both the mass concentrations and light absorption efficiency of BC, which were responsible for 40%–50% and 50%–60%, respectively. Our work identified strong haze‐BC‐climate connections across the NCP and YRD and highlighted the importance of BC in the effects of haze pollution on regional climate. Plain Language Summary: Black carbon (BC) aerosols strongly absorb solar radiation and have a large contribution to both haze pollution and climate warming. The model estimates of BC radiative effects during their lifecycle have considerable uncertainties due to the complex physical and chemical processes of BC aerosols from local emissions to long‐range transport in the atmosphere. Improving estimates of BC radiative effects requires some direct measurements of BC absorption properties to constrain model predictions. However, it challenges field measurements to obtain this information at the regional scale. Our simultaneous observations in the North China Plain and the Yangtze River Delta using a single‐particle technique helped to distinguish the regional origins of BC. Based on field measurements, we quantified the optical properties of BC at local and regional scales. The results showed that the radiative effects of BC at the regional scale were significantly amplified by haze formation and transport, indicating the important role of BC in haze‐climate interactions. The work provides a clue for the simultaneous mitigation of haze pollution and climate warming. Key Points: Bimodal coating feature of black carbon (BC) was found when cross‐regional haze transport occurredCross‐regional haze transport brought 1–3 μg m−3 BC with higher absorption efficiency than locally emitted BCA case study identified strong haze‐BC‐climate connections across northern and eastern China [ABSTRACT FROM AUTHOR]

This study examines hilly terrain's effect on black carbon (BC) dispersion. The apportionment of distinct sources obtained by a two-component mixing model (Aethalometer: AE-33) using improved radiative transfer equations showed the dominance of traffic-derived black carbon (BCFF) emissions in the study region. The AERMOD was used to model BC emissions from moving traffic as a line source and parking lot as area source using observational and WRF-processed meteorology for the winter (January to March 2020). The model results showed that the BC levels substantially vary with local meteorological conditions, traffic volume, and composition. The hilly terrain obstructs the winds and develops a negative pressure loading to a vacuum on the other side of the hills, which promotes the accumulation of emissions, causing high BC concentrations. The pockets of higher concentration were seen at the locations where steep slopes were associated with low winds (<1 m s−1) and hill fogs. The AERMOD model, after statistical evaluation against the observational datasets, has been applied to study the reduction in BCFF concentrations due to the implementation of Indian emission norms as mitigation measures, i.e., BS-IV (equivalent to Euro 4) and BS-VI (equivalent to Euro 6). It was found that the BCFF concentrations for BS-IV and BS-VI reduced by 35% and 75%, respectively. The model was also used to study the contribution of the different vehicular categories to BC concentration. [ABSTRACT FROM AUTHOR]

We reported the seasonal variations of columnar aerosol optical depth (AOD) and equivalent black carbon (EBC) from December 2018 to November 2019 in semi-arid station, Anantapur. Furthermore, using the two-component source apportionment model, we estimated the contribution of biomass burning (EBCbb) and fossil fuel combustion (EBCff) to the total EBC. The high AOD values at shorter wavelengths indicate that particle loading occurs primarily in fine mode aerosols. The high AOD500 was observed in the month of May (0.77 ± 0.19), and the low was in July (0.32 ± 0.11). The seasonal highest mean AOD500 was noticed during the summer (0.67 ± 0.12) followed by winter (0.49 ± 0.01), post-monsoon (0.43 ± 0.15) and monsoon (0.43 ± 0.17). The results revealed that both local emissions and long-range transported aerosols are primarily responsible for a significant spectral and temporal variability in AOD. In winter, the Angstrom exponent (α) was relatively high, whereas it was low in monsoon season. The mass concentrations of EBC, EBCff and EBCbb showed a strong diurnal and seasonal variations with in the study period. The highest and lowest EBC was noticed in winter and monsoon that is 2.64 ± 0.32, and 0.625 ± 0.16 μg/m3, respectively. The percentage contribution of annual mean EBC was 52.13% during the day and 47.86% during the night, respectively. With an average of 91.48%, EBCff contributes the most to total EBC during the study period. Furthermore, during all seasons, the hourly mean concentrations of EBC showed good agreement (r = 80) between the observed (Aethalometer) and MERRA-2 (Modern-Era Retrospective Study for Research and Applications). According to the MERRA-2 winds and Moderate Resolution Imaging Spectroradiometer (MODIS), the prevalence of fine mode particles throughout winter and summer is connected with continental air masses originating from India's central and northern regions. [ABSTRACT FROM AUTHOR]

Black carbon and charcoal's limitation in detecting low-temperature fires could be a major obstacle in observing paleofire. To reconstruct a low-temperature fire pattern and vegetation changes in the Changyi in the northern Shandong Peninsula over the last 5000 years, we used molecular biomarker (levoglucosan and its isomers) and hydrocarbons (n-alkanes), along with charcoal and black carbon in the sediment sites. An increase in the amounts of coniferous flammable fuels could provide the biomass required to maintain low-temperature conditions for smoldering fires during the prehistoric period when wildfires occurred during 5300–5100 yr BP. These fires primarily coincided with cooling climate events that began approximately 5300 yr BP onward. Significant levoglucosan fluxes at approximately 4400–3600 yr BP and 1300–1000 yr BP were thought to be closely linked to intensive anthropogenic burning practices and the climate-controlled sedimentary wet environments, coinciding with the periods of the Longshan (4600–4000 yr B.P), Yueshi Cultures （4000–3500 yr B.P）and Tang Dynasty（1300–1100 yr B.P）. During those times, the original forest landscape in the study region was gradually replaced by a fire-prone open forest, where low-temperature smoldering fires could be sustained by the abundance of biomass for producing fuel from open forests. In contrast, the levoglucosan fluxes remained at low values between the intervals of 3600–3200 yr BP and 1000–0 yr BP, whereas the charcoal fluxes showed a significant increase in the Changyi profile. Moreover, the positive correlation between the levoglucosan and char fluxes in sediments suggested that levoglucosan could be an indicator of regional fires or biomass burning at low temperatures. The ratios between levoglucosan and its isomers indicated that levoglucosan are derived from the combustion of softwood at the study site. Futhermore, Levoglucosan in sediments was used in this study to document the changes in vegetation and low-temperature regional biomass burning, as well as the shifts in human land use and the cultural development in response to climate change. Compared to the two biomass-burning proxies (black carbon and charcoal), levoglucosan in sediments can additionally provide supplementary information to understand paleofire. [ABSTRACT FROM AUTHOR]

The composition of marine aerosol is quite complex, and its sources are diverse. Across the East China Sea (ECS) and the Yellow Sea (YS), multi-dimensional analysis of marine aerosols was conducted. The characteristics of carbonaceous aerosols and gaseous pollutants were explored through in situ ship-based observation, MERRA-2 reanalysis datasets and TROPOMI data from Sentinel-5P satellite. Black carbon (BC)'s average concentration is 1.35 ± 0.78 μg/m3, with high-value BC observed during the cruise. Through HYSPLIT trajectory analysis, sources of BC were from the northern Eurasian continent, the Shandong Peninsula, the ECS and Northwest Pacific Ocean (NWPO). The transport of marine sources like ship emissions cannot be ignored. According to the absorption Angstrom exponent (AAE), BC originates from biomass burning (BB) in the shortwave band (~370 nm) and from fossil fuel combustion in the longwave band (~660 nm). Organic carbon (OC), sulfate (SO42−) and BC report higher Angstrom exponent (AE) while dust and sea salt reveal lower AE, which can be utilized to classify the aerosols as being fine- or coarse-mode, respectively. OC has the highest AE (ECS: 1.98, YS: 2.01), indicating that anthropogenic activities could be a significant source. The process of biomass burning aerosol (BBA) mixed with sea salt could contribute to the decline in BBA's AE. Ship emissions may affect the distribution of tropospheric nitrogen dioxide (NO2) in the ECS, especially during the COVID-19 pandemic. Tropospheric NO2 over the YS has the highest value (up to 12 × 1015 molec/cm2). Stratospheric NO2 has a ladder-like distribution from north to south, and the variation gradient was lower than that in the troposphere. Carbon monoxide (CO) accumulates in the south and east of the ECS and the east of the YS, while the variation over the eastern YS is relatively frequent. Seas near the Korean Peninsula have extremely high CO concentration (up to 1.35 × 1017 molec/cm2). [ABSTRACT FROM AUTHOR]

Black carbon (BC) in snow plays an important role to accelerate snow melting. However, current studies mostly focused on BC concentrations, few on their size distributions in snow which affected BC's effect on albedo changes. Here we presented refractory BC (rBC) concentrations and size distributions in snow collected from Chinese Altai Mountains in Central Asia from November 2016 to April 2017. The results revealed that the average rBC concentrations were 5.77 and 2.82 ng g−1 for the surface snow and sub-surface snow, which were relatively higher in the melting season (April) than that in winter (November–January). The mass median volume-equivalent diameter of rBC size in surface snow was approximately at 120–150 nm, which was typically smaller than that in the atmosphere (about 200 nm for urban atmosphere). However, there existed no specific mass median volume-equivalent diameter of BC size for sub-surface snow in winter. While during the melting season, the median mass size of rBC in sub-surface snow was similar to that in surface snow. Backward trajectories indicated that anthropogenic sourced BC dominated rBC in snow (70%–85%). This study will promote our understanding on BC size distributions in snow, and highlight the possible impact of BC size on climate effect. [ABSTRACT FROM AUTHOR]

Black carbon (BC) is a significant source of air pollution since it impacts public health and climate change. Understanding its distribution in the complex urban environment is challenging. We integrated a land use model with four machine learning models to estimate traffic-related BC concentrations in Oakland, CA. Random Forest was the best-performing model, with regression coefficient (R2) values of 0.701 on the train set and 0.695 on the validation set with a root mean square error (RMSE) of 0.210 mg/m3. Vehicle speed and local road systems were the most sensitive variables in estimating BC concentrations. However, this approach was inefficient at identifying hyperlocal hotspots, especially in a complex urban environment where highways and truck routes are significant emission sources. Using the land use method to estimate BC concentrations may lead to underestimating some localized hotspots. This work can improve air quality exposure assessment for vulnerable populations and help emphasize potential environmental justice issues. [ABSTRACT FROM AUTHOR]

Atmospheric dry deposition of black carbon (BC) is a significant but poorly understood and inadequately described process in aerosol-climate models. The 40-year detailed dry deposition velocities of hydrophilic BC over China from 1981 to 2020 were systematically studied based on the MERRA-2 reanalysis data, which hopefully will be beneficial for its applications in atmospheric systems for climate and air quality. The average dry deposition flux of hydrophilic BC over China was 0.00059 ± 0.00014 μg m−2 s−1, while its dry deposition velocity was estimated to be 0.00051 ± 0.00004 m s−1. The monthly mean dry deposition fluxes of hydrophilic BC varied nearly 1.5 fold, ranging from the lowest 0.00046 ± 0.00011 μg m−2 s−1 in August to the highest 0.00068 ± 0.00019 μg m−2 s−1 in January. The spring season had the highest mean dry deposition flux of hydrophilic BC, followed by summer and winter, whereas autumn showed relatively weaker dry deposition flux. The mean dry deposition velocities of hydrophilic BC over the Beijing-Tianjin-Hebei region, Yangtze River Delta, Pearl River Delta and Tibet Plateau were estimated to be 0.00042 ± 0.00004, 0.00042 ± 0.00004, 0.00051 ± 0.00006 and 0.00078 ± 0.00005 m s−1, respectively. The monthly and seasonal patterns of dry deposition velocities of hydrophilic BC differed from each other in different regions, and high air temperature or surface wind speed seemed to fortify dry deposition velocities of hydrophilic BC. Our study pointed to high dry deposition flux of hydrophilic BC in the northern China Plain and Sichuan Basin but large dry deposition velocities in the Tibet Plateau region. [ABSTRACT FROM AUTHOR]

For air quality management it is becoming increasingly important to be able to assess the quantity and properties of biomass-burning-related aerosol. Due to different chemical compositions and morphologies, black carbon (BC) and brown carbon (BrC) demonstrate diverse optical properties as well as an impact on air quality. In this study, we analyzed the chemical composition and light-absorbing properties of carbonaceous aerosol at an urban background station during the residential heating season. In addition, BC and BrC levels were assessed in six different areas in the city characterized by different predominant domestic heating systems. Positive matrix factorization (PMF) and BrC attribution analysis revealed that BrC mainly consisted of biomass-burning-related organic aerosol (BBOA) (up to 95%). The mass absorption cross-section at 370 nm for BBOA factors varied between 1.41 m2g−1 and 2.63 m2g−1. The study of six different areas in the city showed that the input of BrC to the total light absorption coefficient within the city varied between 33% and 70%. In addition, the worst air quality was present in areas with numerous old wooden houses with outdated heating systems where significantly increased BC and BrC levels were observed. [ABSTRACT FROM AUTHOR]

The parameterization of deep convection is one of the primary sources of uncertainties in regional climate simulations. Due to computational constraints, long-term kilometer-scale simulations with explicit deep convection have been limited, especially over East Asia. We here conduct a pair of 10-years (2001–2010) reference simulations, one convection-parameterizing simulation at 12 km (0.11 ∘ ) resolution covering the CORDEX East Asia domain, and one 4.4-km (0.04 ∘ ) convection-permitting simulation over a subdomain. The two simulations are driven by the ERA5 reanalysis and the coarser-resolution simulation, respectively. The 4.4-km convection-permitting simulation noticeably improves the representation of the top-of-atmosphere outgoing longwave and shortwave radiation as well as precipitation intensity. In addition, sensitivity simulations are performed with perturbed sulfate and black carbon aerosols, considering the direct and semi-direct aerosol radiative effects. For the simulations with sulfate aerosol perturbations, the cloud radiative effect partly offsets the aerosol radiative effects. Decreasing sulfate aerosols leads to low-level warming, destabilizing the atmospheric stratification and thereby increasing mean precipitation and the frequency of wet days. Increasing sulfate aerosols leads to an approximately opposite response. For the simulations with black carbon aerosol perturbations, there is some near-surface warming for both increases and decreases in aerosol concentration. Also, there are significant changes in cloud cover, but changes in precipitation are comparatively weak. While for sulfate aerosol perturbations the response is approximately linear (in the sense that positive and negative perturbations yield approximately opposite effects), the response to black carbon aerosol perturbations is more complex and shows some nonlinearity, regardless of the treatment of deep convection in the simulations. We present a simple interpretation for this surprising result. [ABSTRACT FROM AUTHOR]

Aiming to create more sustainable cities it is necessary to understand and manage different ecological factors which influence human health. One of such factors is black carbon (BC) in atmosphere, which currently is not commonly monitored by environmental monitoring systems. The aim of this research was to estimate by indirect approach the relation between eBC (equivalent of black carbon) concentration and other air pollutants in order to define approximate level of eBC in more efficient approach. The study was conducted in Wrocław (Poland) in October 2021, and combined data on eBC concentration (measured by microaethalometer), air quality (from national environmental monitoring system) and traffic (from municipal traffic management system). Quantile regression was used to assess the relationship between the concentrations of pollutants. The obtained results show that for rise 1 mg·m-3 of carbon monoxide, eBC concentration rise between 4.2 and 8.0 µg·m-3, depending on the period of a day. Precision of eBC concentration evaluation is influenced by sun light which results in higher precision of defining a scaling factor for night hours. Outcomes of this study constitute an added value to understanding of interconnections between different factors describing environmental conditions in cities and might be helpful for more effective environmental assessment of human habitats. [ABSTRACT FROM AUTHOR]