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Black carbon (BC), primarily originating from fossil fuel and biomass combustion, holds significance for global carbon cycling, climate change, and human health. Despite a lake's role as a carbon sink, detailed information about BC sedimentary burial flux and sink in its sediment remains insufficiently explored. The current study investigates the distribution, sources, and burial flux of BC and its subtypes (char and soot) in the surface sediment of Daye Lake, the largest lake in Huangshi City, central China. BC concentrations in the sediment ranged from 0.10 to 3.60 mg/g, corresponding to 0.40%–17.02% of organic carbon (OC). Higher values of BC and BC/OC observed in the western region suggest direct terrestrial input via river discharge and surface runoff, influenced by anthropogenic activities. In contrast, variations in char/soot ratios reflect diverse combustion sources and hydrological dynamics in different regions. The indications from BC/OC and char/soot ratios imply that fossil fuel combustion is the predominant sources. The weak correlations between BC and OC suggest that they may come from different sources or undergo different processes that affect their distribution in the lake sediment. However, a stronger correlation was observed between BC and soot, as well as between char and soot, indicating potential similarities in their input pathways. The BC burial flux displays notable variations across the lake, ranging from 0.69 to 24.07 g/m2/yr, with elevated values observed in the western region. The BC sink in the sediments of Daye Lake was estimated to be 0.635 Gg/yr. Though locally small, it significantly contributes to the broader picture of BC burial in Chinese lakes and the global distribution of BC in lake ecosystems. [ABSTRACT FROM AUTHOR]

Fine particulate matter (PM 2.5) has been implicated in various health concerns. However, a comprehensive understanding of the specific PM 2.5 components affecting depression remains limited. This study conducted a Cox proportional-hazards model to assess the effect of PM 2.5 components on the incidence of depression based on the China Health and Retirement Longitudinal Study (CHARLS). Participants with 10-item Center for Epidemiologic Studies Depression Scale (CESD-10) score of 10 or higher were classified as exhibiting depression. Our findings demonstrated a significant positive correlation between long-term exposure to black carbon (BC), sulfate (SO 4 2−), and organic matter (OM) components of PM 2.5 and the prevalence of depression. Per 1 Interquartile Range (IQR) increment in 3-year average concentrations of BC, OM, and SO 4 2− were associated with the hazard ratio (HR) of 1.54 (95 % confidence intervals (CI): 1.44, 1.64), 1.24 (95% CI : 1.16, 1.34) and 1.25 (95% CI : 1.16, 1.35). Notably, females, younger individuals, those with lower educational levels, urban residents, individuals who were single, widowed, or divorced, and those living in multi-story houses exhibited heightened vulnerability to the adverse effects of PM 2.5 components on depression. Firstly, pollutant data is confined to subjects' fixed addresses, overlooking travel and international residence history. Secondly, the analysis only incorporates five fine particulate components, leaving room for further investigation into the remaining fine particulate components in future studies. This study provides robust evidence supporting the detrimental impact of PM 2.5 components on depression. The identification of specific vulnerable populations contributes to a deeper understanding of the underlying mechanisms involved in the relationship between PM 2.5 components and depression. • This study explore the association between PM 2.5 components and depression. • Black carbon, sulfate, and organic matter have significant impacts on depression. • Females, who living in multi-story house were susceptible to the PM 2.5 components. [ABSTRACT FROM AUTHOR]

This study evaluates the engine performance and life-cycle emissions of hydrogen enriched LNG as a pragmatic solution to more rapidly introducing hydrogen as marine fuel, while waiting for pure hydrogen fuel infrastructure to be built. Engine experiments in a 4-stroke marine diesel engine operating with a spark-ignited pre-chamber ignition system were conducted, and a wide range of engine exhaust emissions measurements including CH 4 , N 2 O, H 2 , and particulate matter (black carbon emission evaluation) were recorded at varying engine loads. The fuel compositions ranged from pure LNG operation to pure hydrogen operation and also included pure conventional diesel fuel oil for comparison. The research methodology integrates engine tests with a full well-to-wake life-cycle assessment (LCA). The impact of using 39.6% hydrogen by energy fraction in natural gas reduced GHG emission by 37.8% on a life-cycle basis at 50% engine load, which could mean a significant reduction of GHG emissions. • Analysis of Hydrogen enriched LNG GHG impact through LCA approach (Well-to-Wake). • A mid-term solution to introduce Hydrogen as maritime fuel. • Experiment of Hydrogen enriched LNG on maritime scale test engine laboratory. • GHG analysis of measured emission data for CO, CO 2 , N 2 O, NO X , PM, CH 4 , H 2. • Detailed climate impact of CH 4 , N 2 O and Black Carbon (BC). [ABSTRACT FROM AUTHOR]

• The risks of cardiovascular and respiratory diseases decline with PM 2.5 in Beijing. • Short periods of lockdown have little effect on long-term changes in health risks. • Ni, Cr, Pb, As, and BC in PM 2.5 show high carcinogenic risks in Beijing. • Health risks from traffic and biomass burning are more prominent in Beijing. • PM 2.5 mass concentration has decreased, but the risks of toxic components are still high. A comprehensive health risk assessment of PM 2.5 is meaningful to understand the current status and directions regarding further improving air quality from the perspective of human health. In this study, we evaluated the health risks of PM 2.5 as well as highly toxic inorganic components, including heavy metals (HMs) and black carbon (BC) based on long-term observations in Beijing from 2019 to 2021. Our results showed that the relative risks of chronic obstructive pulmonary disease, lung cancer, acute lower respiratory tract infection, ischemic heart disease, and stroke decreased by 4.07%-9.30% in 2020 and 2.12%-6.70% in 2021 compared with 2019. However, they were still at high levels ranging from 1.26 to 1.77, in particular, stroke showed the highest value in 2021. Mn had the highest hazard quotient (HQ , from 2.18 to 2.56) for adults from 2019 to 2021, while Ni, Cr, Pb, As, and BC showed high carcinogenic risks (CR > 1.0×10−6) for adults. The HQ values of Mn and As and the CR values of Pb and As showed constant or slight upwards trends during our observations, which is in contrast to the downward trends of other HMs and PM 2.5. Mn, Cr, and BC are crucial toxicants in PM 2.5. A significant shrink of southern region sourcesof HMs and BCshrank suggests the increased importance of local sources. Industry, dust, and biomass burning are the major contributors to the non-carcinogenic risks, while traffic emissions and industry are the dominant contributors to the carcinogenic risks in Beijing. [Display omitted] [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]

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]

The ambient air quality has improved significantly under strict emission controls in Beijing, China over the last decade. Black carbon (BC), as a short-lived climate forcer in ambient aerosols, profoundly impacts the air quality and climate. Previous studies have demonstrated a decline in the mass concentration of BC. In this study, we characterized the chemical compositions and size distributions of BC-containing particles during the cold season of 2022 in Beijing using state-of-the-art instruments capable of exclusively measuring BC-containing particles. The optical properties of BC-containing particles were further calculated based on the Mie theory. Moreover, we compared the properties of BC-containing particles in 2022 with the results of previous studies. The results showed that the diameters of BC cores became larger while the coating thickness of BC-containing particles became thinner in 2022. For the coating materials, the mass fraction of nitrate increased obviously, and even replaced organic matter as the dominant component during the peak of the pollution period. Variations in chemical compositions and size distributions resulted in lower mass absorption cross-sections (MAC) of BC-containing particles from 10.5 ± 1.1 m2/g in 2016 to 7.3 ± 0.8 m2/g in 2022, reduced by 30.5%. Our results demonstrate the synergistic benefits of air pollution control in improving air quality and mitigating climate change. Therefore, the MAC of BC adopted in climate models should vary with the changing air pollution levels. This study emphasizes that it is imperative to conduct long-term observations of BC-containing particles to better estimate BC's climate effects. [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 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]

We report the results of source apportionment of combustion-derived black carbon (BC), in PM 2.5 aerosols collected from the East Asian continental outflow region at two islands; Okinawa and Fukue during the period from October 2009 to May 2010. The 14C contents of BC from Okinawa (Cape Hedo) and Fukue islands (Fukue) varied from 24.4 to 34.2 pMC and from 18.1 to 43.0 pMC, respectively. Source apportionment of BC was conducted by using a simple 14C mass balance model and a dual-isotope Bayesian Markov chain Monte Carlo model. Biomass combustion contributions (e.g., wood fuel and crop residues) were 23–31 % (mean 27 ± 3 %) at Cape Hedo and 15–38 % (mean 27 ± 12 %) at Fukue. Both sites were equally affected by biomass combustion, whose levels are similar to those observed in the hotspot regions (megacities) in China. Fossil fuel contributions (e.g., oil, gasoline, and diesel) were 69–77 % (mean 74 ± 3 %) with 2–69 % from coal and 3–76 % from liquid fossil at Cape Hedo, and 55–85 % (mean 73 ± 12 %) at Fukue with 3 % from coal and 53–56 % from liquid fuel for the early winter. Those variations for both sites showed significantly different source region-specific trends and this trend was also consistent with the results of the air mass trajectory analysis with a higher contribution of coal-BC from North China including Beijing, and East China including Shanghai. In spring, we found a higher contribution of liquid fossil fuel combustion (e.g., traffic) over the East China Sea, including Pacific air masses, suggesting that the possible contribution of ship emissions was relatively high. Although our results for isotopes-based source apportionment of BC are preliminary, these findings suggest that long-term monitoring of BC aerosols, even in remote sites of Asian outflows, and source-specific descriptions of BC are important to improve climate models. We also recommend further measurements for implementing regionally tailored mitigation. [ABSTRACT FROM AUTHOR]

Black carbon (BC) has importance regarding aerosol composition, radiative balance, and human exposure. This study adopted a backward-trajectory approach to quantify the origins of BC from anthropogenic emissions (B C An) and open biomass burning (B C BB) transported to Xishuangbanna in 2017. Haze months, between haze and clean months, and clean months in Xishuangbanna were defined according to daily PM 2.5 concentrations of >75, 35–75, and <35 µg/m3, respectively. Results showed that the transport efficiency density (TED) of BC transported to Xishuangbanna was controlled by the prevailing winds in different seasons. The yearly contributions to the effective emission intensity of B C An and B C BB transported to Xishuangbanna were 52% and 48%, respectively. However, when haze occurred in Xishuangbanna, the average B C An and B C BB contributions were 23% and 77%, respectively. This suggests that open biomass burning (BB) becomes the dominant source in haze months. Myanmar, India, and Laos were the dominant source regions of BC transported to Xishuangbanna during haze months, accounting for 59%, 18%, and 13% of the total, respectively. Furthermore, India was identified as the most important source regions of B C An transported to Xishuangbanna in haze months, accounting for 14%. The two countries making the greatest contributions to B C BB transported to Xishuangbanna were Myanmar and Laos in haze months, accounting for 55% and 13%, respectively. BC emissions from Xishuangbanna had minimal effects on the results of the present study. It is suggested that open BB in Myanmar and Laos, and anthropogenic emissions in India were responsible for poor air quality in Xishuangbanna. [Display omitted] [ABSTRACT FROM AUTHOR]

[Display omitted] • Cultural practices such as the Diwali celebration exacerbates air pollution. • Widespread use of firecrackers releases a large amount of atmospheric pollutants. • Elevated concentrations of PM2.5, black carbon, and PAHs recorded during Diwali. • Short-term release of high concentrations of particulate matter may spread Covid-19. • Airborne PM2.5, black carbon, and PAHs may serve as a carrier of the Covid-19 virus. Emissions of black carbon (BC) and polycyclic aromatic hydrocarbons (PAHs) from various anthropogenic activities are often reported, yet cultural practices such as the multi-day Diwali festival and its influences on the emissions of these compounds are often overlooked. Major activities during this festival include burning rows of oil-filled earthen lamps (diyas) and fireworks (bursting of crackers). A comprehensive field investigation was conducted to document the role of Diwali celebrations on the releases of BC and PAHs during the ongoing Covid pandemic. The results show that large-scale releases of BC and PAHs were observed on the first day of Diwali compared to the remaining four days. BC and PM 2.5 mass concentrations throughout the monitoring period ranged from 3.24 to 27.64 µg m−3 and 83.33 to 288.13 µg m−3, respectively. The source apportionment was performed based on the calculated backward trajectories. The results show that the contribution of fossil fuel emission at Adityapur (ADP), Sakchi (SAK), and Gamharia (GMA) was approximately 36.1 %, 34.4 %, and 55.56 %, while biomass burning contribution was approx. 56.9 %, 59.9 %, 41.67 %, respectively. The result showed that fossil fuel emissions were lower compared to biomass combustion during Diwali. Simultaneously, PAHs diagnostic ratio showed that vehicular discharge and coal burning significantly contributed to PAHs at these study sites. [ABSTRACT FROM AUTHOR]

This work uses a mixture of observations from surface remote sensing (AERONET) and satellite remote sensing (OMI) to uniquely compute the atmospheric column loading of black carbon (BC) mass concentration density (MCD) and number concentration density (NCD) on a grid-by-grid, day-by-day basis at 0.25°x0.25° over rapidly developing and biomass burning (BB) impacted regions in South, Southeast, and East Asia. This mixture of observations is uniformly analyzed based on OMI NO 2 retrievals, OMI Near ultraviolet band absorption aerosol optical depth and single scattering albedo (SSA), and AERONET visible and near-infrared band SSA observations, in connection with an inversely applied MIE mixing model approach. This method uniquely solves for the unbiased spatial and temporal domains based on variance maximization of daily NO 2. These locations in space and time are then used to quantify the distribution of all possible individual particle core and refractory shell sizes as constrained by all band-by-band observations of SSA from AERONET. Finally, the range of NCD and MCD are computed from the constrained range of per-particle core and refractory shell size on a grid-by-grid and day-by-day basis. The maps of MCD and NCD are consistent in space and time with known urban, industrial, and BB sources. The statistical distributions are found to be non-normal, with the region-wide mean, 25th, 50th, and 75th percentile MCD [mg/m2] of 90.3, 56.1, 81.1, and 111 respectively, and NCD [x1012 particles/m2] of 8.76, 4.63, 7.39, and 11.3 respectively. On a grid-by-grid basis, a significant amount of variation is found, particularly over Myanmar, Laos, northern Thailand, and Vietnam, with this subregional mean, 25th, 50th, and 75th MCD [mg/m2] of 90.7, 56.1, 81.3, and 112 respectively and NCD [x1012 particles/m2] of 9.66, 5.49, 8.33, and 12.3 respectively. On a day-to-day basis, events are determined 121 days in 2016, during which the computed statistics of MCD and NCD have mean and uncertainty ranges which scale with each other. However, there are 11 days where the uncertainty ratio of NCD values is larger than 1 while the uncertainty ratio of MCD is small, and 5 days where the reverse is observed, indicating that the particle size is strongly atypical on these days, consistent with mixed aerosol sources, a substantial change in the aerosol aging, or other such factors including a substantial region of overlap between BB and urban sources. The high values observed from March to May lead to an extended BB season as compared to previous work focusing on fire radiative power, NO 2 , and models, which show a shorter season (usually ending in early April). The results are consistent with BC being able to transport significant distances. The new approach is anticipated to provide support for improving radiative forcing calculations, estimating emissions inventories, and providing a basis by which models can compare against observations. • SSA observations from AERONET and OMI merged to estimate per-particle mixing state. • BC column number and mass estimated on a day-by-day and grid-by-grid basis. • Retrieved BC absorption, size, and mixing state are not normally distributed. • High BC mass and number originate from both biomass burning and rapid urbanization. [ABSTRACT FROM AUTHOR]

• Estimating BC using a gradient boosting machine, MAIAC AOD, and in-situ data • Spatio-temporal analysis of BC in Tehran from 2010 to 2021 • Assessment of carcinogenic and non-carcinogenic health risks from BC exposure • BC exposure cancer risk exceeds recommended levels by the US EPA • Green spaces help reduce BC concentrations in urban areas Black Carbon (BC) is an atmospheric pollutant with considerable adverse effects on human health, increasing the chance of cardiovascular disorders, respiratory issues, and cancers in exposed individuals. Accordingly, studying BC in urban areas is essential for understanding its associated health risks. In this study, the Multi-Angle Implementation of Atmospheric Correction (MAIAC) retrieved Aerosol Optical Depth (AOD) remote sensing data from the Moderate Resolution Imaging Spectroradiometer (MODIS), along with in situ observations of BC concentration and meteorological parameters were utilized to estimate BC concentration in Tehran. In this regard, an ensemble machine learning algorithm, Gradient Boosting Machine (GBM), was employed to estimate BC concentration from 2010 to 2021, enabling a spatiotemporal analysis of BC levels in Tehran. Subsequently, the carcinogenic and non-carcinogenic effects of BC on children and adults were examined, as well as its relationship to urban green spaces. The Root Mean Square Error (RMSE), Mean Absolute Error (MAE), and Adjusted R-squared (R2 adj), values for BC estimation ranged from 0.80 to 1.59 μg/m3, 0.59 to 1.10 μg/m3, and 0.70 to 0.94, respectively, indicating the promising performance of the GBM algorithm. The estimated annual average BC concentration over 11 years was 6.18± 2.46 μg/m3. Spatial variations in BC concentration and hotspot analysis at 99% and 95% confidence levels, showed that hotspots were primarily concentrated in the central and southern parts of Tehran. In contrast, cold spots were more scattered across the western and northeastern parts of the city. The cancer risk (CR) from BC exposure exceeded the recommended risk levels (1 × 10⁻⁶ to 1 × 10⁻⁴) established by the US Environmental Protection Agency (US EPA), demonstrating severe health risks for people in Tehran exposed to the current levels of BC concentrations. The average Hazard Quotient (HQ) value across all areas of Tehran was below the threshold value of 1, indicating that the non-carcinogenic health risk remains within acceptable limits. Results regarding green spaces indicated that greenery significantly influences BC concentration, revealing a negative correlation between green space coverage and BC concentration. [ABSTRACT FROM AUTHOR]

The aethalometer model (AM) is widely used for source apportionment (SA) of black carbon (BC) in regions with mixed BC sources despite being initially developed for a relatively simplistic and low-pollution environments. The present study interrogates the applicability of AM in highly polluted metropolitan environments by comparing its results with the more nuanced Positive Matrix Factorization (PMF) model. The measurements were conducted in Delhi during the winter and summer season. PMF apportions the BC into diverse sources by taking help from complementary trace elemental measurements, thereby acknowledging the complex pollution landscape of the Delhi region. The AM estimates BC bb (BC from biomass burning) and BC ff (BC from fossil fuel combustion) contributions as 48.3% and 51.7% during the winter and 16.6% and 83.4% during the summer, respectively. In contrast, the PMF model-derived biomass burning factor is the dominant source of BC during both winter and summer seasons, contributing 53.9% and 44% of the total BC, respectively. The decrease in light absorption at UV wavelengths of biomass-burning aerosols owing to escalated ambient aging is posited to be the reason for BC bb underprediction by the AM model during summers. Furthermore, while the AM model identifies fossil fuel combustion as the only other BC source apart from biomass burning, the PMF model apportions BC to five additional sources during winter, including vehicle emissions (22.9%), Pb-rich factor (10%), power plant (5.7%), waste incineration (4%) and industrial emission (3.6%). The contribution of these BC sources during summer is vehicular emission (16.5%), power plant (14.5%), waste incineration (11.5%), Pb-rich factor (9.5%), and industrial emission (4%). Additionally, the spectral variation of the light absorption properties of black carbon (b BCabs) and brown carbon (b BrCabs), delta-C effect, and sensitivity of the AM are reported for the study period. The present study cautions that BC source apportionment can be complex in highly polluted metropolitan environments, and complementary tracer measurements are recommended for reliable results. [Display omitted] • SA results from AM and PMF differed during the summer and winter seasons. • AM estimated BC bb and BC ff contributions as 48.3% and 51.7% in winter, and 16.6% and 83.4% in summer, respectively. • Biomass burning factor obtained from the PMF model is the primary BC source, contributing 53.9% in winter and 44% in summer. • Rabi crop residual burning in nearby states elevates BC BB levels over Delhi during the summer. • Ambient aging is the likely reason for BC bb underprediction by the AM model during summers. [ABSTRACT FROM AUTHOR]

This study evaluated the exposure of commuters to particulate matter (PM), black carbon (BC), and ultrafine particulate matter (UFP) concentrations in five different traffic microenvironments (bike, bus, taxi, electric motorbike, and subway) under various conditions, such as regular and dust days, weekdays and weekends, and peak and off-peak commute hours in Nanjing, China. In the morning peak hours, bicycle commuters were exposed to the highest PM concentration, those on buses to the highest BC concentration (3.4 ± 3.0 μg/m3), and those on buses and taxis to the highest UFP number concentration. Throughout the rides, the commuter on the subway had the lowest mean exposure concentration of PM, BC, and UFP number. Bicycle commuters (16.25 μg/km) had the highest total inhaled dose of PM2.5, followed by e-bikers (1.98 μg/km), bus riders (1.28 μg/km), taxi riders (0.69 μg/km), and subway users (0.45 μg/km). Weekday PM2.5 exposure levels (115 μg/m3) and BC exposure levels (1.8 μg/m3) were higher than weekend levels (170% and 158%, respectively). The mean exposure concentration of PM10 (1299 ± 1286 μg/m3) in the evening peak of dust days was 803% and 994% higher than the mean concentrations on weekdays and holidays, respectively. PM2.5, PM10, and BC concentrations on dust days were significantly higher than those on weekdays and holidays. The overall mean ratios of PM1/PM2.5 and PM2.5/PM10 were 0.47 and 0.36, respectively, and the five commuting microenvironments had higher proportions of 2.5–10 μm and 1–2.5 μm particles in PM10 and PM2.5, respectively. Reducing the sources of particulate matter in the corresponding particle size ranges could lower exposure levels. [Display omitted] • Subway commuters are exposed to the lowest concentrations of pollutants. • Bus and taxi had the highest concentrations of BC and UFP-number. • Highest PM exposure and inhaled dose were observed by bicycle commuters. • PM exposure on weekdays was 1.2–1.9 times higher than that on weekends. • PM 2.5 , PM 10 and BC were highest on dust days, while PM 1 was highest on weekdays. [ABSTRACT FROM AUTHOR]

Black carbon (BC) is a harmful pollutant to human health and the environment. The aim of this paper is to evaluate the local contribution of road traffic and residential biomass burning to BC pollution levels at urban scale by implementing an integrated modelling approach with high spatial and temporal resolution. The traffic emission was extended to include BC emission factors considering road network as line emission sources. A new module to calculate emissions from residential biomass burning was developed based on the heating degree days methodology and local surveys. The modelling approach implemented in Coimbra, Portugal, was validated with observations collected during a six-month monitoring campaign at urban traffic and urban background stations using thermo-optical and optical methods. At the traffic station, modelling results showed that 86% of BC concentrations are related to traffic activity, which are mostly due to hot exhaust emissions (76%). Nevertheless, biomass burning has a significant contribution in the whole urban area during winter. The results of monthly average BC concentrations obtained from dispersion modelling revealed a contribution from local road traffic and residential biomass burning emissions of around 4 μg m−3 at both monitoring sites during the coldest period, but this contribution was two times higher for the hotspots identified within the urban area. Moreover, hourly values at hotspots obtained from the modelling may achieve 85 μg m−3, thus stressing the importance of spatial and temporal analysis with high resolution. The validation approach applied in this work highlight the need for more transparency in defining "black carbon" reported by modelling to ensure comparability with measurements obtained by different techniques. • BC modelling was implemented at urban scale and validated using 6-month measurements. • Road transport contributes more than 80% to BC concentrations at a traffic site. • Biomass burning has a significant contribution to urban BC during winter. • Modelling agrees with measurements of EC, but underestimates optical eBC. [ABSTRACT FROM AUTHOR]

• Investigated ultrafine particles (UFP) near an aircraft route. • Identified Taxiing as the major source of UFP. • Ancillary pollutants (nitrogen oxides, etc.) were mainly from external sources. • Observed unimodal size distributions from Taxiing (17 nm) and Takeoff (23 nm). • Detected aluminum-UFP, peaking in the Aitken mode. The rapid expansion of the aviation sector raises concerns about air quality impacts within and around airports. Ultrafine particles (UFP, diameter < 100 nm) are of particular concern due to their potential adverse health effects. In this study, particle number concentrations (PNC), particle number size distribution (PNSD), and other ancillary pollutants such as particulate matter (PM), nitrogen oxides (NO X), black carbon (BC), sulfur dioxide (SO 2), ozone (O 3), carbon monoxide (CO) and benzene, as well as organic markers and trace elements (in quasi-UFP) were measured at Barcelona-El Prat Airport (80 m and 250 m from the main taxiway and runway). Comparisons were made with an urban background (UB) location, and source apportionment of PNSD was performed using Positive Matrix Factorization (PMF). PNC inside the airport was nine-fold higher than the UB, and fifteen-fold higher when considering only nucleation mode particles (< 25 nm). Six sources contributing to PNC were identified inside the airport: Taxiing (48.7 %; mode diameter = 17 nm), Industrial/Shipping (7.4 %; mode diameter = 35 nm), Diesel (3.9 %; mode diameter = 64 nm), Regional recirculation (1.1 %; mode diameter = 100 nm), Photonucleation (16.6 %; mode diameter = 13 nm) and Takeoff (18.5 %; mode diameter = 23 nm). Due to the measurement location and prevailing wind patterns, no significant contributions from landings were detected. Chemical analysis of quasi-UFP collected on Electrical Low-Pressure Impactor (ELPI +) filters (stages 2 to 6: 17–165 nm) revealed higher concentrations (> 2-fold) of Fe, Al, Cr, Cu, Mo, Mn, Pb, Ti, and Sb at the airport compared to the UB, with Al exhibiting the most pronounced disparity. Generally, PAH levels were low at both sites, although concentrations were higher at the airport relative to the UB. Overall, this study provides a comprehensive understanding of UFP within a major European airport, identifying the different sources contributing to PNC and PNSD. [ABSTRACT FROM AUTHOR]

Accurate measurements of cloud condensation nuclei (CCN) activity and hygroscopicity of black carbon (BC)-containing particles are particularly important because of the positive climate forcing from these particles. Such measurements are typically conducted on particles selected by a Differential Mobility Analyzer (DMA), which in addition to singly charged particles transmits multiply charged larger particles that have the same electrical mobility. These larger particles activate at lower supersaturations than the singly charged particles, biasing measurements and resulting in overestimation of CCN activity and hygroscopicity parameter (κ). Here, we measure the CCN activity and determine κ for different BC surrogates with electrical mobility diameters from 100 to 200 nm selected 1) only by electrical mobility with a DMA, and 2) by both electrical mobility and mass using a DMA and a Centrifugal Particle Mass Analyzer (CPMA), thus allowing selection of only singly charged particles. We demonstrate the use of the DMA-CPMA system in resolving biases caused by multiply charged particles, and we show that the effect of multiple charging on the CCN activity of the BC particles is strongly influenced by morphology dispersion, i.e., the variability due to the range of morphologies of particles that have the same electrical mobility and mass. Our findings show that electrical mobility-based methods alone are unlikely to lead to accurate results in measurements of CCN activation and hygroscopicity of BC particles, even for those with a more compact morphology. [Display omitted] • Mobility-based methods for particle selection introduce multiply charged particles. • The presence of multiply charged particles overestimates the CCN activity of black carbon. • A DMA-CPMA system can reduce errors in CCN activity caused by multiple charging. • Morphology dispersion influences the effect of multiple charging on CCN activity. [ABSTRACT FROM AUTHOR]

[Display omitted] • A more convincing approach to simulating the production of magnetic black carbon. • Use materials that are closer to life. The siderite and pyrite used are common iron ores. • A more prescriptive and convincing approach to model building was adopted. Coal fly ash contains rich black carbon (BC) that is generated by insufficient combustion during the process of coal-fired power generation. Siderite (FeCO 3) and pyrite (FeS 2), two of the most common iron ores in coal, can be easily to combine with black carbon to form magnetic mixtures, leading to serious environmental pollution. The combustion was simulated by placing a portion of clean coal with the same concentration of iron source at the outlet and intake of the tube furnace. Oxygen was consumed by the sample near the air intake to provide an oxygen deficient environment for the sample near the air outlet. The suitable gas flow rate for the simulated combustion was 20 mL/min. There is an overall increasing trend in the content of BC in the combustion products mixed with FeCO 3. The presence of elemental Fe (1.2 wt%) in the case of incomplete combustion produces an inhibitory effect on the generation of BC. As Fe content increases, the proportion of spherical encapsulated structures in the combustion products increases, which suppresses the consumption of BC. The same inhibitory effect of elemental Fe was present in the ferrous disulfide simulations. In addition, the presence of Fe 7 S 8 indicates that the formation of iron oxides was reduced, resulting in reducing the inhibition of polycyclic aromatic hydrocarbon oxidation and a decrease in BC yield. The BC model was determined by SS 13C NMR, and the data simulation of the binding of BC to magnetic substances was carried out based on density functional theory. The works provide a theoretical basis for establishing a traceability method for magnetic BC. [ABSTRACT FROM AUTHOR]

This research introduces an innovative framework that effectively integrates the Land Use Regression (LUR) model with an explainable machine learning methodology, thereby enhancing the causal understanding of how land use variables impact Black Carbon (BC) concentrations in complex urban landscapes. Through the development and application of a LUR-based Bayesian Network (BN) model to detailed, mobile-based BC measurements, we have successfully decoded the causal relationships and conditional probabilities linking diverse urban land use variables to BC levels. The BN model demonstrates notable prediction accuracy on the test set, with an R2 of 0.59 and an NRMSE of 0.65. Among the varied land use variables analyzed, proximity to the port is identified as the dominant factor contributing to BC hotspots. Moreover, the synergistic effect of port proximity and truck routes emerges as a key driver of spatially clustered BC hotspots, a complex phenomenon not adequately captured by conventional machine learning and deep learning models. The insights revealed through this study are vital not just for enhancing air pollution prediction and exposure analysis but also for informing urban planning and policymaking, offering valuable, actionable insights. • LUR-based BN model can explain the causal relationship driving BC concentration variations in urban environment. • Proximity to the port is the dominant factor contributing to hyper-local BC hotspots in Oakland, CA. • The synergistic effect of port proximity and truck routes is a key driver of spatially clustered BC hotspots. [ABSTRACT FROM AUTHOR]

Mitigation of black carbon (BC) is a potent short-term measure for climate and environmental policy due to the short lifetime of BC particles in the atmosphere. Fewer BC emissions would decelerate warming especially in the Arctic and bring significant co-benefits particularly in populous countries owing to BC's negative public health, food security and socio-economic effects. However, scientific knowledge on BC remains uncertain regarding the measurement, monitoring and precise effects of BC while the respective global policy framework is fragmented. To address this situation, we scrutinize the science/policy nexus in BC mitigation on the regional level where some promising openings exist. For this end, our new analytical framework focuses on policy entrepreneurs, their interests and cognitive frames, and the structural environment. Utilising content analysis of expert interviews and document data, three cases are covered with significant policy entrepreneurship on BC. First, we examine Finland 's high-profile BC initiative, finding it to frame BC pollution as an Arctic climate threat. Second, Finland's research, development and innovation cluster, which has substantial expertise on air pollution, frames BC as a public health hazard, and scopes prospects for policy frameworks helping to open markets for mitigation technologies and solutions. Third, the Climate and Clean Air Coalition approaches BC with a wide multipollutant frame, driven by broad socio-economic and developmental interests. The Finnish initiative's potential is found to suffer from insufficient coordination with the RDI cluster. Both Finland's BC specific and the CCAC's wider multipollutant frame can in different ways contribute to abatement. • A new analytical framework to study policy entrepreneurs in emission mitigation. • We compare Finnish actors and the Climate and Clean Air Coalition (CCAC). • Finland's official black carbon initiative focuses on Arctic climate interests. • Finland's initiative is insufficiently coordinated with the country's RDI sector. • The Finnish initiative can be combined with the CCAC's multipollutant frame. [ABSTRACT FROM AUTHOR]

• This K-Pg boundary preserves evidence of both the impact and Deccan volcanism. • Enrichments in PGE and the black carbon indicate contributions from the impact. • Another PGE anomalies were detected approximately 50 cm below the K-Pg boundary. • PGE anomalies and lithology across this boundary were impacted by Deccan eruptions. • The most voluminous Deccan eruptions occurred following a hiatus after the impact. The Cretaceous-Paleogene (K-Pg) extinction is linked to two primary causes: the Chicxulub asteroid impact in Mexico and the Deccan Traps eruptions in India. While substantial geological evidence supporting both events has been found worldwide, to understand their potential interactions, it is crucial to study sites that preserve records of both events simultaneously. The terrestrial K-Pg boundary located in the Sichuan Basin, China (∼15,500 km from the Chicxulub Crater and ∼5,600 km from the Deccan Traps correspond to 66 Ma), preserves evidence of both the Chicxulub impact and the Deccan Traps eruptions, along with the effects of subsequent events on the earlier ones. It offers a new perspective on the K-Pg boundary. Detailed petrological examination and geochemical analyses, including platinum-group element (PGE) and black carbon concentrations, were conducted across a 2 m K-Pg boundary section. The K-Pg boundary layer (∼2.5 cm thick) is composed of very fine-grained, brick-red sandstone and exhibits significant enrichments in Ir (9.050 ppb) and Os (10.72 ppb), along with elevated black carbon (1.10 ‰), strongly indicating contributions from the impact. Intriguingly, another PGE anomaly was detected approximately 50 cm below the K-Pg boundary. The strata surrounding the K-Pg boundary display evidence of alteration by acidic and HSˉ-rich fluids. These fluids likely caused the observed downward migration of PGE within the boundary, resulting in two distinct PGE anomalies - one at the K-Pg boundary itself and another approximately 50 cm below. These fluids resulted in the overlying sandstones exhibiting minimal matrix content and bleached the underlying brick-red sandstones. Volcanic gas emissions from the Deccan Traps after the impact are a potential source for these fluids. Our findings support the hypothesis that the most voluminous Deccan eruptions had occurred close to, but not necessarily immediately after, the Chicxulub impact, potentially lasting 100–131 ka. The hiatus after the impact weakens the possibility of a direct causal link between the Deccan eruptions and the impact. [Display omitted] [ABSTRACT FROM AUTHOR]

The present study investigated the aerosol-radiation-cloud interaction of anthropogenic black carbon (BC) during a severe fog-haze event by utilizing WRF-Chem, multi-satellite and in-situ observations, reanalyses datasets, and HYSPLIT model. The WRF-Chem model adequately captured the regional distribution of aerosol, cloud, and meteorological variables over the study domain. The maximum BC surface concentration (≥7 μg m−3) was predominantly evident over densely populated central and lower Indo-Gangetic Plain (IGP) regions. Although smoke aerosols usually persisted within 4 km above the surface at daylight hours, they reached as high as 6 km during nighttime, specifically over the central IGP regions. The heavily influenced areas by BC aerosols expanded to almost the entire landmass and the continental outflow region upon doubling the anthropogenic emission. The geographical distribution of maximum perturbations in net shortwave radiation flux at the surface closely matched the spatial patterns of the highest BC concentration, indicating a crucial role of BC in directly preventing the incoming sunlight from reaching the surface. Consequently, the reduced solar radiation at the ground might result in substantial surface cooling (between −0.3 and −0.5 °C), eventually prohibiting surface evapotranspiration and diminishing the outgoing sensible and latent heat fluxes. Also, more amplified cooling in the polluted atmosphere can prevent further development of the planetary boundary layer (PBL), increasing particle entrapment near the surface via an 'aerosol-radiation-PBL' feedback loop. However, the most striking contrast between the two scenarios (typical and polluted) was the prolonged and intensified warming (0.5–0.8 °C) in the mid-troposphere, causing a remarkable drop in moisture (more than two to three times) and hence burn-off of liquid cloud droplets due to the semi-direct effect of increased BC aerosols. The intense mid-tropospheric heating could remarkably enhance the updraft velocity, supporting the vertical transport of the additional moisture to higher altitudes, forming more ice clouds at night. Therefore, the current study highlighted the urgency of mitigating anthropogenic BC emissions in highly polluted regions since increased emissions could considerably worsen severe fog-haze conditions and influence both liquid water and ice clouds, depending on the atmospheric conditions. • Maximum black carbon concentration is observed over the central and lower Indo-Gangetic Plain in the usual scenario. • Perturbation in surface fluxes due to near-surface cooling is more prominent in the polluted scenario. • Black carbon-induced prolonged and intense mid-tropospheric heating is more prominent than the near-surface cooling. • Stronger mid-tropospheric heating accelerates vertical moisture transport and promotes the formation of more ice clouds. [ABSTRACT FROM AUTHOR]

Associations between indoor air pollution from fine particulate matter (PM with aerodynamic diameter d p < 2.5 μm) and human health are poorly understood. Here, we analyse the concentration-response curves for fine and ultrafine PM, the gene expression, and the methylation patterns in human bronchial epithelial cells (BEAS-2B) exposed at the air-liquid interface (ALI) within a classroom in downtown Rome. Our results document the upregulation of aryl hydrocarbon receptor (AhR) and genes associated with xenobiotic metabolism (CYP1A1 and CYP1B1) in response to single exposure of cells to fresh urban aerosols at low fine PM mass concentrations within the classroom. This is evidenced by concentrations of ultrafine particles (UFPs, dp < 0.1 μm), polycyclic aromatic hydrocarbons (PAH), and ratios of black carbon (BC) to organic aerosol (OA). Additionally, an interleukin 18 (IL-18) down-regulation was found during periods of high human occupancy. Despite the observed gene expression dysregulation, no changes were detected in the methylation levels of the promoter regions of these genes, indicating that the altered gene expression is not linked to changes in DNA methylation and suggesting the involvement of another epigenetic mechanism in the gene regulation. Gene expression changes at low exposure doses have been previously reported. Here, we add the possibility that lung epithelial cells, when singly exposed to real environmental concentrations of fine PM that translate into ultra-low doses of treatment, may undergo epigenetic alteration in the expression of genes related to xenobiotic metabolism. Our findings provide a perspective for future indoor air quality regulations. We underscore the potential role of indoor UFPs as carriers of toxic molecules with low-pressure weather conditions, when rainfall and strong winds may favour low levels of fine PM. [Display omitted] • No significant correlation was found between PM 1 and gene regulation of BEAS-2B cell. • AhR and CYP upregulation was linked to fresh urban aerosol and low condensation sink. • IL-18 was down-regulated during periods of high human occupancy. • The promoter methylation levels of AhR, CYP1A1, CYP1B1 and IL-18 were not changes. [ABSTRACT FROM AUTHOR]

Incorporating jets of forced air into biomass cookstove combustion has been shown to potentially decrease harmful emissions, leading to a variety of designs in recent years. These have shown mixed success in terms of real-world performance, usability, and durability. The Jet-Flame forced draft retrofit accessory was recently developed to implement forced jets of primary air at a low cost into a wide range of types of cookstoves using a small 1.5-W fan housed in a low-cost cast iron body to be inserted beneath the fuel bed of a biomass cooking fire. This research sought to quantify the potential efficiency and emissions performance impacts of the Jet-Flame when installed in six different types of biomass cookstoves (three open or shielded fires and three rocket stoves) versus the natural draft performance of each. The effect of the operating fan voltage was also measured. A series of tests following a modified ISO 19867-1:2018 protocol were performed in the laboratory using the Aprovecho Laboratory Emissions Measurement System (LEMS) equipped with additional oxygen and temperature sensors. Results for each stove carefully tended with a single layer of sticks showed that the global average PM 2.5 reduction with the Jet-Flame was 89 % relative to the natural draft cases, with larger relative improvements seen in the most rudimentary stoves. CO was reduced by a global average of 74 %, reaching tier 4 or 5 for all stoves. Thermal efficiency was also improved by 34 % when calculated without taking into account the energy content of the remaining char (or 21 % with char), illustrating the value of burning char to provide cooking energy rather than leaving it unburned in the combustion chamber as is common in many natural draft stoves. Time to boil was also reduced by 8 %. In addition, adjusting the voltage of the jet-flame assisted in modulating firepower, improving the usability of the stove. These results indicate a strong potential for the Jet-Flame to help reduce emissions and fuel consumption in a wide range of cookstove designs at a relatively low cost or need for changes in behavior, fuel, or cooking device. The unit also provides enhanced usability in terms of ease of startup, cooking speed, low PM emissions at high power, and burning char. Additional studies are needed to measure performance in the field and under a variety of operational conditions. [ABSTRACT FROM AUTHOR]

Motivated by the application of internally air-assisted flares and recent anomalous data that black carbon (BC) emissions changes are not monotonic with the amount of air added inside the fuel stream, a burner was designed to study the flow, emissions, and stability aspects of the existence of both normal and inverse jet diffusion flames in close proximity. Since the radius of curvature of a burner affects all aspects of combustion, such as dynamics, stability, flame structure, and emissions, a slot burner configuration, inspired by the Wolfhard-Parker burner, was adopted. This multi-slot burner consists of five parallel rectangular slots (i.e. , the central slot for the inner air, sandwiched between two fuel slots, and surrounded by two outer air slots). When operated with laminar fuel and air flows, this burner produced flame sheets at each fuel-air mixing layer with open optical access to all the flows. Flow fields were characterized using two-dimensional two-component particle image velocimetry, while simultaneous single-lens reflex photography was used to establish the overall height and the location of the flames. Emission measurements specifically targeted BC, a precursor of soot, and oxides of nitrogen (NO x). The experimental test conditions involved constant flows of outer air and propane, and variable inner air flow. At one extreme, i.e. , zero inner air flow, two flame bases were produced at the interfaces between the fuel and outer air streams. These flames merged to produce a normal diffusion flame. With the addition of inner air, two more flame bases appeared (referred to as the inner flame) and formed an inverse diffusion flame. With increasing inner air flow, the inner flame transitioned from a closed-tip flame, to an open-tip flame, and eventually to a lifted flame. With increasing inner air flow, the NO x emissions remained constant while the BC emissions, which were 3 g/kg-fuel with no inner air, rose by an order of magnitude as it became an open-tip flame. Only when the inner flame finally lifted off due to the inner air flow, did the BC emissions collapse to near zero. Phenomenological models associated with the importance of partial premixing were proposed to explain this collapse, thereby generalizing this finding to other combustion systems when attempting to reduce BC emissions through secondary internal air addition. [ABSTRACT FROM AUTHOR]

Significant PM 2.5 pollution has been prevalent on a regional scale in East Asia including a megacity Seoul in South Korea. Here, we explore fine-aerosol episodes occurred in Seoul during the Satellite Integrated Joint monitoring of Air Quality (SIJAQ) campaign from October to November of the 2021, focusing on experimental evidences of heterogeneous reactions to form secondary aerosol under a highly oxidized atmospheric condition. At this urban site in Seoul, vehicle exhaust was the clear source of fresh emissions, leading to a high level of NO and small refractory black carbon (rBC) particles (mass median diameter of 162 nm ± 16 nm) in the morning time. The hourly mass concentration of PM 2.5 ranged from 5.3 μg m−3 to 146.1 μg m−3, averaging at 24.5 ± 22.2 μg m−3. During the campaign, the most intense episode, EP3 (November 18–21), recorded an average PM 2.5 concentration of 72.5 ± 38.2 μg m−3, peaking at 146.1 μg m−3, was characterized by relatively higher temperature (∼12 °C) and relative humidity (67 %) on average thoroughly governed by continental migratory high and westerly winds. While the average NO 3 − concentration was 27.7 μg m−3, four times the whole campaign's average, EP3 was highlighted by a high morning NO 2 /NO x ratio and significantly elevated daytime and nighttime O x (O 3 +NO 2) concentrations compared to non-episode days. Throughout the entire campaign, NO z surrogate (NO 2(CL) -NO 2(T)), O x , and F moderate + thick (the combined number fractions of moderately and thickly coated-rBC particles) tended to increase with the PM 2.5 concentration. During the daytime, as PM 2.5 increased, F moderate + thick showed a monotonic increase, accompanied by RH rising from 54 ± 16% to 63 ± 11%. In contrast, at nighttime of humid condition with RH often exceeding 70% the enhancement of F moderate + thick was more sensitive to condensable gas levels than RH. Given that high levels of PM 2.5 (>60 μg m−3) were observed only during EP3, enhanced levels of NO z surrogate, O x , F moderate + thick, and RH were evident characteristics of EP3. Such chemical and meteorological conditions suggest that the chemically enhanced oxidation state was evident during EP3, which promoted the formation of secondary aerosols on primary particles including rBC, especially under conditions of elevated RH. Considering the recent trend of increasing number of vehicles and rising atmospheric O 3 concentrations in East Asia, future studies should be well designed to investigate the detailed mechanisms involved in heterogeneous reactions that lead to the formation of secondary aerosols. • The increase in coated BC number fraction coincided with the increase in O x and NO z surrogate (NO 2(CL) -NO 2(CAPS)) levels. • Amount of water molecules played an important role in formation of BC coatings at day and night time. • Chemically enhanced oxidation state facilitated the formation of secondary aerosols on BC particles especially under humid condition. [ABSTRACT FROM AUTHOR]

[Display omitted] • First extensive neolithic chernozemic horizon found in south-eastern Bavaria, Germany. • Rectangular, field-like shape of core area with chernozemic horizon. • Radiometric dating proves neolithic age of carbon in chernozemic horizon. • Dark colour of chernozemic horizon caused by black carbon content. • Traces of neolithic fertilization, liming and charcoal application. The polygenetic development and age of black soils and Chernozems in Central Europe are widely discussed. The development and age of these soils in Germany is still not fully understood. While a significant share of Chernozems in Central Germany is assumed to have formed naturally during the early Holocene, such a natural formation can be excluded for all of southern Germany for paleoclimatic and –vegetative reasons. Therefore, soils with chernic horizons of natural origin are not to be expected south of the central German uplands. Active soil alteration by the human population in the Neolithic has also been observed to lead to Chernozem-like soils in other regions of Germany, like Lower Saxony and North Rhine-Westphalia. The unexpected black horizon investigated in this study is located close to Straubing in Bavaria, southeast Germany. The prevailing natural soil type in the area is a calcic Luvisol on loess substrate. The black horizon is located in close proximity to a neolithic settlement and its graveyard. We hypothesise that the inhabitants of the nearby neolithic settlement used the area with the black horizon as an agricultural field and were managing it actively. The core area with the most pronounced black horizon is rectangular and comprises within the excavation a surface of ca. 0.83 ha. Several decimetres of Holocene colluvium buried the black horizon in the Late Bronze Age and subsequent periods (OSL and 14C-Dating). Dating results from the black horizon prove human impact on the soil starting in the Linearbandkeramik (LBK) period (cal BC 5,209–4,911 , 14C-Dating). NMR- and FTIR-DRIFT-analysis show high contents of pyrogenic carbon in the black horizon, which is responsible for its dark colour, even though the mean share of carbon is not higher than 0.50 ± 0.03 % (mean ± se). These results match those of recent literature and, therefore, indicate that neolithic farmers also applied their targeted soil amendment practices in southern Germany. This follows archaeological findings on the colonization of the area by the neolithic settlers: Primordially coming from the Fertile Crescent (northern Middle East), they followed the Danube through the Pannonian Region and brought their agronomic knowledge from the prior settlement area, where their active soil management is archaeologically proven. [ABSTRACT FROM AUTHOR]

In the present study the generation of non-linear optical (NLO) effects, such as second harmonic generation (SHG), by black carbon particles, also named soot, and by other types of nanoparticles in aerosol phase is quantified and analysed. Its potential for measuring the specific surface area of an aerosol is put forward. SHG is a Non Linear Optical phenomenon that is typically used in biosciences and fundamental physics and has shown to have large potential for the investigation of surface sensitive phenomena. It exists in two forms, coherent SHG and incoherent SHG, also named Hyper Rayleigh Scattering (HRS). While applications on particles in solution or organic molecules located on the surface of droplets exist, the SHG naturally induced by solid nanoparticles in aerosol phase without any SHG enhancing additive has neither been detected nor quantified yet. The present work aims at narrowing this gap by exposing a jet of well-characterized nanoaerosols to a femtosecond laser featuring high peak pulse energies allowing to induce NLO phenomena. The experiments are carried out in an innovative optical setup allowing to analyse the NLO response resolved in time, wavelength and angle, thus having the capability to isolate SHG from other phenomena, such as laser filamentation. The optical setup was calibrated in order to quantify the generated signal power and optimized in order to have a high sensitivity and in order to avoid NLO generation from its own optical elements. The results confirm that soot particles, as well as DEHS droplets and arc generated carbon nanoparticles, feature SHG at intensities that are more than 7 orders of magnitude smaller than that of static light scattering. SHG depends in particular on aggregate and/or monomer size. On the other hand, SHG induced by soot does not seem to depend on the organic or elementary carbon content. The experiments also show that the detected NLO signal increases linearly with particle surface area, independently of the particle shape or composition. Finally, the angular response of NLO signal is fundamentally different from that of linear scattering. Due to the isotropic nature of the angular response, the observed SHG signal is probably non-coherent and thus related to Hyper Raleigh Scattering. These findings show the potential of non-linear optics, in particular to quantify in situ the specific surface of an aerosol. Giving access to this information which is crucial in the evaluation of toxicity of aerosols, the present work can thus give way to a new class of laser based diagnostics for aerosols. • Non-linear optical interaction between aerosols and laser light is analyzed in-situ • The analysis is done with the help of a novel optical setup • Analysis depends on laser pulse energy, time, wavelength and observation angle • Different types of fractal and non-fractal aerosols were studied • Incoherent second harmonic generation (SHG) is observed • This phenomenon is called Hyper Rayleigh Scattering (HRS) • The measured HRS power is, to our knowledge for the first time, quantified. • A linear link between specific surface area (SSA) and the HRS signal is demonstrated • The results can lead to novel techniques of in-situ SSA measurements • Such measurements are important to evaluate for example the particles' toxicity [ABSTRACT FROM AUTHOR]

Black carbon (BC) is a vital air pollution particulate. Urban agglomeration has complex trade linkages internally and externally. Jing-Jin-Ji (JJJ) is the largest urban agglomeration in northern China and suffers from severe air pollution problems. Despite the importance of BC mitigation and the study area of JJJ, there is a lack of studies exploring the embodied BC emission transfers hidden behind trade within and across the JJJ urban agglomeration at the city scale, given the importance of interregional collaboration among cities for air pollution control. This paper applied the multiregional input-output (MRIO) analysis and structure path analysis (SPA) to investigate the impact of trade on the BC emissions in JJJ and identify the critical sectors and supply chains, using the latest available China's city-level MRIO table. The results show that the embodied BC emission intensity in JJJ is 143.17 g/104 yuan, which exceeds the national average (121.89 g/104 yuan). The Construction sector contributes 27.93 % of the total embodied BC emissions in JJJ. The cities of Handan, Tangshan, and Hengshui are the largest providers of emission-intensive products (3.51, 2.83, and 2.05 Gg, respectively) while Beijing is the largest receiver (5.78 Gg). From a supply chain perspective, Coal and Metal Mining are the main upstream industries, accounting for a considerable proportion of the BC emissions supply chain. To enhance the interregional collaborative governance of BC pollution control in JJJ, horizontal governance mechanisms, decentralized and polycentric urban planning, industrial clustering and technology upgrading, and effective policies for specific regions and industrial sectors are suggested. • BC emission intensity is roughly negatively correlated with the economic situation. • Embodied BC emissions in JJJ and other Chinese regions are calculated. • BC emissions in JJJ are largely attributed to eastern coastal China. • Reduction strategies based on urban agglomeration cooperation are suggested. [ABSTRACT FROM AUTHOR]

Heavy-duty diesel vehicles (HDDVs) significantly contribute to atmospheric nitrogen oxides (NO X) and black carbon (BC), with high emitters within the HDDV fleet impacting the total emissions. However, emission patterns and contributions of high emitters are rarely explored from a fleet-perspective. We investigated NO X and BC emission factors (EFs) from 1925 HDDVs in Shenzhen by the plume-chasing method, and found that the fleet-average EFs decreased with stricter emission standards. Unexpectedly, the average NO X EF for the China IV fleet was comparable with that for the China III fleet due to possible ineffective aftertreatment in high-emitter sectors of China IV HDDVs. Decreasing trend in average NO X EF since 2017 reflected the effective emission controls by the implementation of China V standard. Besides, semi-trailer tractors exhibited a higher incidence of NO X over-emissions, whereas BC high emitters were more pronounced in box trucks. Total NO X and BC emissions from HDDVs in Shenzhen were revisited, reaching 54.0 and 1.1 Gg·yr−1, with updated NO X EF correcting a 26.2 % underestimation in national guidelines. Notably, eliminating high emitters yields greater emission reduction benefits than merely retiring old HDDVs, with BC reduction outpacing NO X. This study provides new insights into the implementation of targeted emission reduction measures for HDDVs. [Display omitted] • NO x and BC EFs for 1925 HDDVs were measured by plume-chasing method. • NO x EFs for the top 10 % NO x emitters was 2.1-3.0 times EFs for the whole fleet. • Top 10 % BC emitters contribute to 50 % of total emissions in the whole fleet. • High NO x and BC emitters were often associated with specific manufacturers. • Limiting high emitters reduce emissions more efficiently than retiring old HDDVs. [ABSTRACT FROM AUTHOR]

The 31st FISU Summer World University Games (SWUG) was held in Chengdu, southwestern China, from July 22 to August 8, 2023. A series of control measures were carried out to ensure good air quality during the SWUG, providing an opportunity to investigate the atmospheric behaviors of light-absorbing aerosols under such a substantial disturbance caused by the control measures. To assess the impacts of emission controls on primary pollutants, a field campaign was conducted at a rural site in Chengdu to investigate the characterization of equivalent black carbon (eBC). The changes of eBC concentrations before, during, and after the SWUG were characterized. The sources of eBC were resolved, and the impacts of atmospheric processes on the absorption capacity were also investigated. During the SWUG, the eBC concentration decreased by 12.1 % and 25.3 % compared with those before and after the SWUG. A fossil fuel combustion (eBC ff) and a biomass burning (eBC bb) originated eBC were resolved using the aethalometer model. Both eBC ff and eBC bb decreased during the SWUG, indicating the effectiveness of control measures. After the SWUG, the influence of biomass burning emissions became more and more significant, and the contribution of brown carbon (BrC) to light absorption at 370–660 nm increased by 52, 19, 7, 6, and 17 % compared to those during the SWUG. As the biomass burning emitted aerosols aged, the absorption Ångström exponent and b abs (BrC 370nm) decreased gradually, which was mainly due to the photobleaching of the chromophores during the daytime. eBC ff was mainly affected by strong wind, while high eBC bb concentration was mainly attributed to the gradual accumulation of biomass-burning emissions near the observation site. The results show the significant reduction of eBC with the implementation of the air pollution mitigation campaign, and provide insights on the impacts of atmospheric processes on BC optical properties during summertime. [Display omitted] • Black carbon reduced significantly during the Summer World University Games. • Fossil fuel combustion and biomass burning were main sources of black carbon. • Higher absorption Ångström exponent was attributed to biomass-burning emissions. • Brown carbon absorption coefficient reduced as biomass-burning organic aerosol aged. [ABSTRACT FROM AUTHOR]

[Display omitted] • Rather than from PM 2.5 total mass, wildfire-specific PM 2.5 concentration was estimated specifically from wildfire. • Associations between wildfire-specific PM 2.5 and its carbonaceous components and six perinatal outcomes were examined. • Short-term in-utero exposure to wildfire-specific PM 2.5 and organic carbon and black carbon components were positively associated with perinatal outcomes. • Exposure-outcome associations showed sociodemographic vulnerability. Epidemiological evidence on the association between wildfire-specific fine particulate matter (PM 2.5) and its carbonaceous components with perinatal outcomes is limited. We aimed to examine the short-term effects of wildfire-specific PM 2.5 and its carbonaceous components on perinatal outcomes. A multicentre cohort of 9743 singleton births during the wildfire seasons from 1 September 2009 to 31 December 2015 across six cities in New South Wales, Australia were linked with daily wildfire-specific PM 2.5 and carbonaceous components (organic carbon and black carbon). Adjusted distributed lag Cox regression models with spatial clustering were performed to estimate daily and cumulative adjusted hazard ratios (aHRs) during the last four gestational weeks for preterm birth, stillbirth, nonvertex presentation, low 5-min Apgar score, special care nursery/neonatal intensive care unit (SCN/NICU) admission, and caesarean section. Daily aHRs per 10 µg/m3 PM 2.5 showed nearly inverted 'U'-shaped positive associations and daily cumulative aHRs that increased with increasing duration of the exposures. The aHRs for lag 0–6 days were 1.17 (95 % CI: 1.04, 1.32) for preterm birth, 1.40 (95 % CI: 1.11, 1.78) for stillbirth, 1.20 (95 % CI: 1.08, 1.33) for nonvertex presentation, 1.12 (95 % CI: 0.93, 1.35) for low 5-min Apgar score, 0.99 (95 % CI: 0.83, 1.19) for SNC/NICU admission, and 1.01 (95 % CI: 0.94, 1.08) for caesarean section. Organic carbon and black carbon components for lag 0–6 days showed positive associations. The highest component-specific aHRs were 1.09 (95 % CI: 1.03, 1.15) and 4.57 (95 % CI: 1.96, 10.68) for stillbirth per 1 µg/m3 organic carbon and black carbon, respectively. The subgroups identified as most vulnerable were female births, births to mothers with low socioeconomic status, and births to mothers with high biothermal exposure. Positive associations of short-term wildfire-specific PM 2.5 exposure and its carbonaceous components with adverse perinatal outcomes suggest that policies to reduce exposure would benefit public health. [ABSTRACT FROM AUTHOR]

Among pollutants released from shipping, black carbon (BC), also known as soot carbon, is of great interest due to its impacts on climate, air quality, human health and ecosystems. BC emitted from ships may enter marine waters and partially transfer to the seawater dissolved phase. In this study, we investigated the optical properties (absorbance and fluorescence) of dissolved organic matter (DOM) derived from BC particles (DOM BC) emitted by ships, which were compared to those of DOM BC of other origins (diesel-powered industrial machine, biomass burning, urban dust), and to terrestrial and marine DOM (DOM TER , DOM MAR). Ship and diesel DOM BC displayed higher ratios of fluorescence maximum intensity to dissolved organic carbon concentration (F max /DOC), higher specific UV absorbance at 254 nm (SUVA 254), and lower fluorescence emission wavelengths than the other tested materials. The parallel factor analysis (PARAFAC)-derived fluorophores of the ship and diesel DOM BC exhibited significant correlations with the concentration of dissolved black carbon (DBC), determined using the benzenepolycarboxylic acid (BPCA) method. Based on these results, we propose the Combustion indeX (COX), to help detecting and tracking ship/fuel combustion pollutions in marine waters. • Black carbon-derived DOM exhibits high F max /DOC ratios and SUVA 254. • Fluorescence and absorbance index of black carbon-derived DOM strongly depends on soot origin. • Specific signature of black carbon-derived DOM exists among natural FDOM found in coastal area. • A new fluorescence index can help to detect and track ship/fuel combustion pollutions in marine waters. [ABSTRACT FROM AUTHOR]

The mud depositional area ("mud area") of the South Yellow Sea serves as a prominent carbon sink within the Eastern Continental Shelf of China, offering crucial insights into human activities and climate fluctuations and its relationship with carbon cycle. This study investigates variations in total organic carbon (TOC) and black carbon (BC) concentrations in South Yellow Sea sediments. By combining 210Pb isotope analysis with grain-size profiling, the study distinguishes organic carbon origins, revealing the complex interplay between human activities and environmental shifts since the Industrial Revolution. The reasons for discrepancies between TOC and BC contents are analyzed, yielding the following results: (1) Sediment core QY-2 predominantly contains terrestrial-sourced organic carbon, primarily derived from the Yellow River and the Yangtze River. (2) Temporal fluctuations of BC in core QY-2 show distinct trends, periodic responses to human activities, particularly peaks in 1937 and 1945, linked to large-scale wars in China. (3) Relaxed carbon emission regulations in China, coupled with industrial growth spurred by the "reform and opening up" policy, led to a continuous rise in BC content from the mid-1960s to the 1980s, peaking in 1980. Subsequently, reduced BC values during the 1990s correlated with emission control policies and the shift from highly polluting domestic coal stoves to cleaner alternatives like liquefied petroleum gas or natural gas stoves. (4) BC content was influenced by the East Asian monsoon and Pacific Decadal Oscillation (PDO), with higher BC accumulation rates occurring in summer and depletion in winter. (5) Interestingly, changes in BC and TOC content exhibited a negative correlation. While grain size and material sources minimally influenced these discrepancies, the primary driver lay in the water's redox environment, impacting other TOC components and thereby causing variations in both TOC and BC content. This study of black carbon sources to sinks in the South Yellow Sea Mud Area holds significant implications for the broader Yellow Sea sedimentary system and provides support for understanding carbon cycle and marine environments. • South Yellow Sea's mud area acts as a significant carbon sink in East China Sea. • Our records show the terrestrial sources (Yellow River and Yangtze River) dominate organic carbon in sediment core QY-2. • Peaks in black carbon contents coincide with the major historical events during the last century. • The East Asian monsoon and PDO could have an impact on black carbon content in South Yellow Sea. • Redox environment can influence organic carbon variations, impacting TOC and BC contents. [ABSTRACT FROM AUTHOR]

Black carbon (BC) is ubiquitous in the environment and is a significant component of the refractory carbon pool. However, its sources, biogeochemical processes, and environmental residence times are poorly understood. One important reason is that the technical protocols for isolating/analyzing BC vary across different matrices, thereby bringing inconsistency among studies on BC in different environment media. Benzene polycarboxylic acids (BPCA), produced by nitric acid oxidation of the condensed aromatic structure that is common in BC and BC-like substances, has been proven to be a useful molecular proxy for tracking BC in the Earth's surface. Here, we introduce a new technical approach for the compound-specific dual-carbon isotope (δ13C and Δ14C) analysis of BPCA. The BPCA compounds are isolated using preparative liquid chromatography, in which trifluoroacetic acid is used in the mobile phase instead of phosphoric acid. This allows complete removal of solvent from the isolated BPCA fraction, so that conversion of BPCA isolates into CO 2 can be done by conventional oxidation methods for off-line Δ14C analysis with accelerator mass spectrometry. Liquid chromatography (void column)-stable carbon isotope ratio mass spectrometry is employed to measure δ13C of the isolated BPCA, leaving as much BPCA carbon amount as possible for 14C analysis. Blockage of oxidation chamber due to incomplete oxidation of other organic acids in the samples is avoided thanks to preliminary isolation of BPCA. We tested the approach by applying it to solid and dissolved BC species in a suite of environmental reference materials, including maize char, coal, riverine natural organic matter (NOM 2R101N), marine sediment (SRM 1941b), urban dust (SRM 1649b), and coke-polluted soils. We assessed the offsets of BPCA-δ13C and BPCA-Δ14C values caused by procedural carbon contaminations to correct measured carbon isotopic values. Paired δ13C-Δ14C data of individual BPCA were plotted to validate and demonstrate the ability of this dual carbon isotope technique in tracking BC across different environmental matrices. We observed slightly different δ13C-Δ14C signatures among individual BPCA, indicating that the less condensed BC may have younger apparent radiocarbon ages. [Display omitted] • We outline a new approach for compound-specific δ13C-Δ14C analysis of BPCA. • Mobile phases of BPCA fractions isolated with HPLC are totally removed. • Validation using BC reference materials of various environmental media. [ABSTRACT FROM AUTHOR]

[Display omitted] • Calligraphy ink treated with acid introduced oxygen groups into BC, maximizing active sites for H 2 O 2 production. • Hydrothermal synthesis resulted in oxygen-functionalized BC (O-BC/ZnIn 2 S 4), enhancing H 2 O 2 production. • In ZnIn 2 S 4 -mediated H 2 O 2 production, we observed a dual phenomenon of production and decomposition. • pH adjustments, especially under basic conditions, led to a ten-fold reduction in ionization, boosting H 2 O 2 production by approximately 14%. Hydrogen peroxide (H 2 O 2), a powerful oxidizing agent, plays a critical role in various sectors including bleaching, wastewater treatment, sterilization, chemical manufacturing, healthcare, energy generation, and environmental cleanup. The conventional method for producing H 2 O 2 , known as the anthraquinone process, faces challenges due to its economic inefficiencies and significant safety concerns. This has spurred interest in developing safer and more environmental friendly photocatalysts for H 2 O 2 production. These photocatalysts, when dispersed in water and exposed to sunlight, generate H 2 O 2 by extracting oxygen from the air and hydrogen from water. Our research explores the use of zinc indium sulfide (ZnIn 2 S 4), a material that is photoactive under visible light, which accounts for about 43 % of the solar spectrum. Initially, the pH of the solution was not modified, leading to the ionization of Zn and In. However, upon optimizing the experimental conditions, we observed a substantial reduction in particle ionization and an increase in H 2 O 2 yield. Additionally, by integrating black carbon with oxygen functional groups into the ZnIn 2 S 4 matrix, we achieved a 14 % increase in production efficiency compared to traditional methods. [ABSTRACT FROM AUTHOR]

Black carbon (BC) aerosol, released into the atmosphere from fuel combustion and biomass burning, is known to be an important short-lived climate forcer (SLCF) because it efficiently absorbs solar radiation and directly heats the atmosphere. Because its accumulation on snow and ice promotes their melting, BC is an important driver of warming, particularly in the Arctic region. Observed surface BC concentrations in the Arctic region show typical seasonal variations, increasing during the winter and spring and decreasing during the warmer season with some peak events in few months of summer, along with large interannual variations. The present study investigates the primary factors influencing the differences in the spatiotemporal surface concentrations of BC in the Arctic region by performing a hemispheric-scale air-quality simulation for the years 2015 and 2016. The model reasonably simulates the observed BC concentration levels and their seasonal patterns, as well as their differences between these two years. This study shows that large year-to-year variability in BC-rich air-mass pathways, such as long-range transport from surrounding regions, and besides these air-mass stagnation within the Arctic region, influence the differences in the Arctic BC concentrations between 2015 and 2016. In addition, the Arctic BC concentrations were also controlled by interannual variations in the amount and distribution of emissions due to the size and the location of open fires, including both Asian crop residue burning in spring and boreal forest fires in summer. [ABSTRACT FROM AUTHOR]

Black carbon is an air pollutant that contributes to Arctic warming, and its control is the subject of multiple international institutions in the region. However, the potential for cost-effective reduction of black carbon emissions in the region is conditioned by the features of the national regulatory systems in relevant countries. This study conducted a comparative analysis of national pollution control systems for land-based sources of black carbon emissions in Arctic states and two key Arctic Council observer states, China and India. Doing so, the study shows that most countries have implemented at least some policies and regulatory measures in most pollution control areas. However, relevant policies are sometimes found outside the conventional domain of air pollution regulation, such as schemes for corporate reporting on sustainability. Substantial differences across countries lie in regulations' stringency and enforcement capacity. In addition, the national governance system, such as the federal systems of the US and Canada, influences the characteristics of black carbon policies and regulations. Furthermore, the application of economic instruments is limited in terms of the country coverage and economic instrument types. These features have implications for the design of domestic and international policies for Arctic black carbon control. [ABSTRACT FROM AUTHOR]