Recommendations for reporting equivalent black carbon (eBC) mass concentrations based on long-term pan-European in-situ observations

Environment International, Journal Year: 2024, Volume and Issue: 185, P. 108553 - 108553

Published: March 1, 2024

A reliable determination of equivalent black carbon (eBC) mass concentrations derived from filter absorption photometers (FAPs) measurements depends on the appropriate quantification cross-section (MAC) for converting coefficient (babs) to eBC. This study investigates spatial–temporal variability MAC obtained simultaneous elemental (EC) and babs performed at 22 sites. We compared different methodologies retrieving eBC integrating options calculating including: locally derived, median value calculated sites, site-specific rolling MAC. The that underwent correction using these methods were identified as LeBC (local MAC), MeBC (median ReBC (Rolling MAC) respectively. Pronounced differences (up more than 50 %) observed between directly provided by FAPs (NeBC; Nominal instrumental due experimental nominal values. was 7.8 ± 3.4 m2 g-1 12 aethalometers 880 nm, 10.6 4.7 10 MAAPs 637 nm. showed significant site seasonal dependencies, with heterogeneous patterns summer winter in regions. In addition, long-term trend analysis revealed statistically (s.s.) decreasing trends EC. Interestingly, we corresponding corrected are not independent way is NeBC EC consistent sites no Conversely, where s.s. trend, while concentration followed same pattern These results underscore importance accounting variations when deriving emphasize necessity incorporating observations constrain uncertainty associated

Language: Английский

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Equal abundance of summertime natural and wintertime anthropogenic Arctic organic aerosols

Nature Geoscience, Journal Year: 2022, Volume and Issue: 15(3), P. 196 - 202

Published: Feb. 28, 2022

Abstract Aerosols play an important yet uncertain role in modulating the radiation balance of sensitive Arctic atmosphere. Organic aerosol is one most abundant, least understood, fractions mass. Here we use data from eight observatories that represent entire to reveal annual cycles anthropogenic and biogenic sources organic aerosol. We show during winter, dominated by emissions, mainly Eurasia, which consist both direct combustion emissions long-range transported, aged pollution. In summer, decreasing pollution replaced natural emissions. These include marine secondary, secondary primary biological have potential be climate modifying cloud condensation nuclei properties acting as ice-nucleating particles. Their source strength or atmospheric processing nutrient availability, solar radiation, temperature snow cover. Our results provide a comprehensive understanding current pan-Arctic aerosol, can used support modelling efforts aim quantify impacts this region.

Language: Английский

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Elucidating the present-day chemical composition, seasonality and source regions of climate-relevant aerosols across the Arctic land surface

Environmental Research Letters, Journal Year: 2022, Volume and Issue: 17(3), P. 034032 - 034032

Published: Feb. 28, 2022

Abstract The Arctic is warming two to three times faster than the global average, and role of aerosols not well constrained. Aerosol number concentrations can be very low in remote environments, rendering local cloud radiative properties highly sensitive available aerosol. composition sources climate-relevant aerosols, affecting formation altering their microphysics, remain largely elusive due a lack harmonized concurrent multi-component, multi-site, multi-season observations. Here, we present dataset on overall chemical seasonal variability total particulate matter (with size cut at 10 μ m, PM , or without any cut) eight observatories representing all sectors. Our holistic observational approach includes Russian Arctic, significant emission source area with less dedicated aerosol monitoring, extends beyond more traditionally studied summer period black carbon/sulfate fine-mode pollutants. major airborne components terms dry mass are sea salt, secondary (non-sea-salt, nss) sulfate, organic (OA), minor contributions from elemental carbon (EC) ammonium. We observe substantial spatiotemporal component ratios, such as EC/OA, ammonium/nss-sulfate OA/nss-sulfate, fractional PM. When combined component-specific back-trajectory analysis identify marine terrestrial origins, companion study by Moschos et al 2022 Nat. Geosci. focusing OA, provides policy-guiding insights into sector-based differences natural anthropogenic sources. In this regard, first reveal regions inner-Arctic biogenic organics, highlight an underappreciated wintertime primary carbonaceous (EC OA) West Siberia, potentially associated oil gas sector. presented assist reducing uncertainties modelling pan-Arctic aerosol-climate interactions, contributors yearly These models then used predict future evolution individual atmospheric light current emerging pollution mitigation measures improved region-specific inventories.

Language: Английский

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Quantifying the Light-Absorption Properties and Molecular Composition of Brown Carbon Aerosol from Sub-Saharan African Biomass Combustion

Environmental Science & Technology, Journal Year: 2024, Volume and Issue: unknown

Published: Feb. 23, 2024

Sub-Saharan Africa is a hotspot for biomass burning (BB)-derived carbonaceous aerosols, including light-absorbing organic (brown) carbon (BrC). However, the chemically complex nature of BrC in BB aerosols from this region not fully understood. We generated smoke chamber through smoldering combustion common sub-Saharan African fuels (hardwoods, cow dung, savanna grass, and leaves). quantified aethalometer-based, real-time light-absorption properties BrC-containing organic-rich accounting variations wavelength, fuel type, relative humidity, photochemical aging conditions. In filter samples collected Botswana winter, we identified 182 species, classified into lignin pyrolysis products, nitroaromatics, coumarins, stilbenes, flavonoids. Using an extensive set standards, determined species-specific mass emission factors. Our analysis revealed linear relationship between combined species contribution to chamber-measured aerosol (0.4–14%) mass-absorption cross-section at 370 nm (0.2–2.2 m2 g–1). Hierarchical clustering resolved key molecular-level components matrix, with photochemically aged emissions leaf cow-dung showing fingerprints similar those found aerosols. These quantitative findings could potentially help refine climate model predictions, aid source apportionment, inform effective air quality management policies human health global climate.

Language: Английский

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Chromophores and chemical composition of brown carbon characterized at an urban kerbside by excitation–emission spectroscopy and mass spectrometry

Atmospheric chemistry and physics, Journal Year: 2022, Volume and Issue: 22(22), P. 14971 - 14986

Published: Nov. 24, 2022

Abstract. The optical properties, chemical composition, and potential chromophores of brown carbon (BrC) aerosol particles were studied during typical summertime wintertime at a kerbside in downtown Karlsruhe, city central Europe. average absorption coefficient mass efficiency 365 nm (Abs365 MAE365) methanol-soluble BrC (MS-BrC) lower the summer period (1.6 ± 0.5 Mm−1, 0.2 m2 g−1) than winter (2.8 1.9 1.1 0.3 g−1). Using parallel factor (PARAFAC) analysis to identify chromophores, two different groups highly oxygenated humic-like substances (HO-HULIS) dominated contributed 96 6 % total fluorescence intensity. In contrast, less-oxygenated HULIS (LO-HULIS) intensity with 57 12 %, followed by HO-HULIS 31 18 %. Positive matrix factorization (PMF) organic compounds detected real time an online spectrometer (AMS) led five characteristic compound classes. statistical PARAFAC components PMF factors showed that LO-HULIS most likely emitted from biomass burning winter. could be low-volatility regional transport oxidation biogenic volatile (VOCs) summer. Five nitro-aromatic (NACs) identified ionization (C7H7O3N, C7H7O4N, C6H5O5N, C6H5O4N, C6H5O3N), which 0.03 0.01 but can explain 0.1 MS-BrC Furthermore, we 316 molecules accounted for 2.5 0.6 mass. (MAE365) 9.5 m2g−1 these compounds, estimate their mean light 1.2 accounting 32 15 nm. This indicates small fraction dominates overall absorption. assigned component had higher molecular weight (265 2 Da) more nitrogen-containing (62 1 %) components. Our shows LO-HULIS, high contribution originating burning, winter, HO-HULIS, fewer as (VOC),

Language: Английский

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Measurement report: Brown carbon aerosol in rural Germany – sources, chemistry, and diurnal variations

Atmospheric chemistry and physics, Journal Year: 2025, Volume and Issue: 25(3), P. 1917 - 1930

Published: Feb. 12, 2025

Abstract. Brown carbon aerosol (BrC) is a major contributor to atmospheric air pollution in Europe, especially winter. Therefore, we studied the chemical composition, diurnal variation, and sources of BrC from 17 February 16 March 2021 at rural location southwest Germany. In total, 178 potential molecules (including 7 nitro aromatic compounds, NACs) were identified particle phase comprising on average 83 ± 44 ng m−3, 31 4 gas contributing 8.5 6.7 m−3 during whole campaign. The light absorption seven NACs was 0.2 Mm−1, 2.2 2.1 % total 370 nm. addition, variations show that gas-phase higher daytime lower night. It mainly controlled by secondary formation (e.g. photooxidation) particle-to-gas partitioning. Correspondingly, particle-phase Secondary dominates with 61 21 %, while 39 originated biomass burning. Furthermore, showed decreasing due photochemical ageing. This study extends current understanding real-time behaviours brown characteristic central Europe.

Language: Английский

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Aerosol spectral optical properties in the Paris urban area and its peri-urban and forested surroundings during summer 2022 from ACROSS surface observations

Atmospheric chemistry and physics, Journal Year: 2025, Volume and Issue: 25(5), P. 3161 - 3189

Published: March 14, 2025

Abstract. The complex refractive index (CRI; n−ik) and the single scattering albedo (SSA) are key parameters driving aerosol direct radiative effect. Their spatial, temporal, spectral variabilities in anthropogenic–biogenic mixed environments poorly understood. In this study, we retrieve CRI SSA (370–950 nm wavelength range) from situ surface optical measurements number size distribution of submicron aerosols at three sites greater Paris area, representative urban city, as well its peri-urban forested rural environments. Measurements were taken part ACROSS (Atmospheric Chemistry Suburban Forest) campaign June–July 2022 under diversified conditions: (1) two heatwaves leading to high levels, (2) an intermediate period with low concentrations, (3) episode long-range-transported fire emissions. retrieved exhibit urban-to-rural gradient, whose intensity is modulated by weather conditions. A full average 1.41−0.037i (urban), 1.52−0.038i (peri-urban), 1.50−0.025i (rural) retrieved. imaginary (k) increases decreases forest when exposed influence plume. Values k > 0.1 < 0.6 520 related a black carbon mass fraction larger than 10 %. Organic found contribute more 50 % up 17 22 (forest) absorption coefficient 370 nm. value 0.022 (370 nm) was measured site for episode.

Language: Английский

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More water-soluble brown carbon after the residential “coal-to-gas” conversion measure in urban Beijing

npj Climate and Atmospheric Science, Journal Year: 2023, Volume and Issue: 6(1)

Published: March 23, 2023

Abstract The implementation of air pollution reduction measures has significantly reduced the concentration atmospheric fine particles (PM 2.5 ) in Beijing, among which “coal-to-gas” conversion may play a crucial role. However, effect this measure on brown carbon (BrC) is not well known. Here, chemical composition BrC humic-like fraction (HULIS-BrC) and water-insoluble (WI-BrC) were characterized for ambient PM samples collected Beijing before after measure. After measure, number HULIS-BrC compounds increased by ~14%, while WI-BrC decreased ~8%. intensity over 90% also correspondingly O/C ratios CHO CHON generally with increase after/before indicating that there more water-soluble highly oxygenated On contrary, than 80% decrease low decreased. This work sheds light differences between suggests future studies residential coal combustion secondary deserve further exploration.

Language: Английский

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In situ vertical observations of the layered structure of air pollution in a continental high-latitude urban boundary layer during winter

Atmospheric chemistry and physics, Journal Year: 2025, Volume and Issue: 25(6), P. 3687 - 3715

Published: March 27, 2025

Abstract. Vertical in situ measurements of aerosols and trace gases were conducted Fairbanks, Alaska, during winter 2022 as part the Alaskan Layered Pollution Chemical Analysis campaign (ALPACA). Using a tethered balloon, study explores dispersion pollutants continental high-latitude stable boundary layer (SBL). 24 flights revealed stratified SBL structure with different pollution layers lowest tens meters atmosphere, offering unprecedented detail. Surface emissions generally accumulated surface mixing (ML) extending to an average 51 m, well-mixed sublayer (MsL) reaching 22 m. The height concentrations within ML strongly influenced by local wind driven nearby topography under anticyclonic conditions. During strong radiative cooling, drainage flow increased turbulence near surface, altering temperature profile deepening ML. Above ML, decreased but showed clear signs freshly released anthropogenic emissions. Higher above elevated inversions, levels similar previously reported Arctic haze concentrations, even though Fairbanks' outflow below inversions up 6 times higher, likely due power plant In indicated that gas particle tracer ratios plumes differed significantly from those surface. Overall, correlated stratification emission heights, emphasizing need for improved representation sources air quality models enhance forecasts.

Language: Английский

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Combined influences of sources and atmospheric bleaching on light absorption of water-soluble brown carbon aerosols

npj Climate and Atmospheric Science, Journal Year: 2023, Volume and Issue: 6(1)

Published: July 29, 2023

Abstract Light-absorbing Brown Carbon (BrC) aerosols partially offset the overall climate-cooling of aerosols. However, evolution BrC light-absorption during atmospheric transport is poorly constrained. Here, we utilize optical properties, ageing-diagnostic δ 13 C-BrC and time to deduce that mass absorption cross-section (MAC WS-BrC ) decreasing by ~50% long-range oversea transport, resulting in a first-order bleaching rate 0.24 day ‒1 3-day transit from continental East Asia south-east Yellow Sea receptor. A modern 14 C signal points strong inverse correlation between age source material. Combining this with results for South reveals striking agreement these two major-emission regions rapid photobleaching higher intrinsic absorptivity stemming biomass burning. The consistency parameters constrained independently outflows both indicates weakening light absorption, thus primarily related photochemical processes rather than sources, likely ubiquitous phenomenon.

Language: Английский

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