The Contribution of Black Carbon-Containing Particles to PM_2.5: Variability, Drivers, and Impacts

Environmental Science & Technology, Journal Year: 2025, Volume and Issue: unknown

Published: March 7, 2025

Atmospheric black carbon (BC) particles play an important role in air pollution, climate change, and human health. Evaluating BC's impacts by model simulation requires understanding of the distribution other aerosol species between those containing BC free during atmospheric aging process. Previous studies observed a large variability mass fraction BC-containing PM2.5 (FBC-containing), complicating determination their impacts. In this work, we conducted field observations various polluted environments across China for process-level FBC-containing. We find that FBC-containing, ranging from 10 to 90%, can be elucidated concept oxidation capacity (AOC). The contrast FBC-containing haze events is determined whether initial freshly emitted limited daytime AOC levels. quantify parametrize resolving under different conditions, indicating efficient formation secondary on when daytime-average concentrations Ox (i.e., O3 + NO2) exceed 80 μg m-3. Our study provides valuable insights into mixing state representations environments, facilitating accurate evaluation models.

Language: Английский

Chemical Evolution of Biomass Burning Aerosols across Wildfire Plumes in the Western U.S.: From Near-Source to Regional Scales

ACS ES&T Air, Journal Year: 2025, Volume and Issue: 2(4), P. 677 - 691

Published: March 28, 2025

The atmospheric processing of biomass burning organic aerosol (BBOA) and its implications for tropospheric physicochemical properties remain uncertain. To address this gap, we investigate the chemical transformation BBOA from wildfire events in western U.S., using data mass spectrometers aboard DOE G-1 aircraft at Mt. Bachelor Observatory (∼2800 m a.s.l.) during summers 2013 2019. This study captures dynamic changes submicron particulate matter (PM1) concentrations profiles within plumes that span a broad range ages, fresh emissions (<30 min) to transported several days. As age, oxidation state aerosols (OA) increases, accompanied by formation secondary components such as phenolic OA (SOA) species, carboxylic acids, potassium sulfate. Early plume evolution is marked evaporation semivolatile alcohol peroxide functional groups, while extended aging produces more oxidized including acids carbonyl compounds. Normalized excess mixing ratios (NEMRs) CO demonstrate complex interplay between evaporation, SOA formation, oxidative loss. Using positive matrix factorization (PMF), identify distinct types representing various stages assess contributions primary formed through reactions. These findings shed light on intricate mechanisms governing characteristics plumes, providing critical insights improve modeling better environmental climatic impacts emissions.

Language: Английский

Chemical Differences between Phenolic Secondary Organic Aerosol Formed through Gas-Phase and Aqueous-Phase Reactions

ACS Earth and Space Chemistry, Journal Year: 2024, Volume and Issue: 8(11), P. 2270 - 2283

Published: Oct. 10, 2024

Phenolic compounds, which are significant emissions from biomass burning (BB), undergo rapid photochemical reactions in both gas and aqueous phases to form secondary organic aerosol, namely, gasSOA aqSOA, respectively. The formation of aqSOA involves different reaction mechanisms, leading product distributions. In this study, we investigate the gaseous guaiacol-a representative BB phenol-to elucidate compositional differences between phenolic gasSOA. Aqueous-phase guaiacol produce higher SOA yields than gas-phase (e.g., roughly 60 vs 30% at one half-life guaiacol). These involve more complex mechanisms exhibit a gradual evolution their counterparts. Initially, forms with high oxidation levels (O/C > 0.82), while starts lower O/C (0.55-0.75). However, prolonged aqueous-phase substantially increase state making its bulk chemical composition closer that Additionally, greater abundance oligomers high-molecular-weight alongside sustained production carboxylic acids. AMS spectral signatures have been identified, which, together tracer ions can aid interpretation field observation data on aerosol aging within smoke. notable highlighted study also underscore importance accurately representing pathways atmospheric models better predict properties environmental impacts.

Language: Английский