Direct observation of aqueous secondary organic aerosol from biomass-burning emissions

Gilardoni, Stefania; Massoli, P.; Paglione, Marco; Giulianelli, L.; Carbone, Claudio; Rinaldi, Matteo; Decesari, Stefano; Sandrini, Silvia; Costabile, Francesca; Gobbi, Gian Paolo; Pietrogrande, Maria Chiara; Visentin, Marco; Scotto, Fabiana; Fuzzi, S.; Facchini, M. C.

doi:10.1073/pnas.1602212113

Cited by 291 publications

(293 citation statements)

References 79 publications

(59 reference statements)

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“…S6), with increased TOC mass concentrations (7.86-16.6 mg L −1 ) in wildfire-influenced cloud water, compared to non-wildfire conditions (0.73-2.16 mg L −1 ), as well as the August-September 2010-2015 averages (Table S1). While the contribution of aqueous SOA formation to the measured TOC cannot be determined in this study, Gilardoni et al (2016) reported production of light-absorbing SOA and an increase in O : C ratio from aqueous-phase processing of biomass burning emissions. Notably, there appears to be a greater diversity of oligomeric compounds present in the wildfire samples (Figs.…”

Section: Canadian Wildfire Influencementioning

confidence: 78%

Biogenic, urban, and wildfire influences on the molecular composition of dissolved organic compounds in cloud water

Cook¹,

Lin²,

Peng³

et al. 2017

Atmos. Chem. Phys.

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Abstract. Organic aerosol formation and transformation occurs within aqueous aerosol and cloud droplets, yet little is known about the composition of high molecular weight organic compounds in cloud water. Cloud water samples collected at Whiteface Mountain, New York, during AugustSeptember 2014 were analyzed by ultra-high-resolution mass spectrometry to investigate the molecular composition of dissolved organic carbon, with a focus on sulfur-and nitrogen-containing compounds. Organic molecular composition was evaluated in the context of cloud water inorganic ion concentrations, pH, and total organic carbon concentrations to gain insights into the sources and aqueous-phase processes of the observed high molecular weight organic compounds. Cloud water acidity was positively correlated with the average oxygen : carbon ratio of the organic constituents, suggesting the possibility for aqueous acid-catalyzed (prior to cloud droplet activation or during/after cloud droplet evaporation) and/or radical (within cloud droplets) oxidation processes. Many tracer compounds recently identified in laboratory studies of bulk aqueous-phase reactions were identified in the cloud water. Organosulfate compounds, with both biogenic and anthropogenic volatile organic compound precursors, were detected for cloud water samples influenced by air masses that had traveled over forested and populated areas. Oxidation products of long-chain (C 10−12 ) alkane precursors were detected during urban influence. Influence of Canadian wildfires resulted in increased numbers of identified sulfur-containing compounds and oligomeric species, including those formed through aqueous-phase reactions involving methylglyoxal. Light-absorbing aqueous-phase products of syringol and guaiacol oxidation were observed in the wildfire-influenced samples, and dinitroaromatic compounds were observed in all cloud water samples (wildfire, biogenic, and urban-influenced). Overall, the cloud water molecular composition depended on air mass source influence and reflected aqueous-phase reactions involving biogenic, urban, and biomass burning precursors.

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Section: Canadian Wildfire Influencementioning

confidence: 78%

Biogenic, urban, and wildfire influences on the molecular composition of dissolved organic compounds in cloud water

Cook¹,

Lin²,

Peng³

et al. 2017

Atmos. Chem. Phys.

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“…More comprehensive understanding of the land biosphere responses is required to quantify the impact of land biosphere to atmospheric compositions under different drought conditions. In addition to changing BVOC emissions, reduced aerosol water content under drought conditions can perturb aqueous-phase formation of SOA from BVOCs, but the impact is not clear (Gilardoni et al, 2016). Changes in anthropogenic emissions under drought conditions are also uncertain.…”

Section: Discussionmentioning

confidence: 99%

Adverse effects of increasing drought on air quality via natural processes

Wang¹,

Xie²,

Dong³

et al. 2017

Atmos. Chem. Phys.

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Abstract. Drought is a recurring extreme of the climate system with well-documented impacts on agriculture and water resources. The strong perturbation of drought to the land biosphere and atmospheric water cycle will affect atmospheric composition, the nature and extent of which are not well understood. Here we present observational evidence that US air quality is significantly correlated with drought severity. Severe droughts during the period of 1990-2014 were found associated with growth-season (March-October) mean enhancements in surface ozone and PM 2.5 of 3.5 ppbv (8 %) and 1.6 µg m −3 (17 %), respectively. The pollutant enhancements associated with droughts do not appear to be affected by the decreasing trend of US anthropogenic emissions, indicating natural processes as the primary cause. Elevated ozone and PM 2.5 are attributed to the combined effects of drought on deposition, natural emissions (wildfires, biogenic volatile organic compounds (BVOCs), and dust), and chemistry. Most climate-chemistry models are not able to reproduce the observed correlations of ozone and PM 2.5 to drought severity. The model deficiencies are partly attributed to the lack of drought-induced changes in land-atmosphere exchanges of reactive gases and particles and misrepresentation of cloud changes under drought conditions. By applying the observed relationships between drought and air pollutants to climate model projected drought occurrences, we estimate an increase of 1-6 % for ground-level O 3 and 1-16 % for PM 2.5 in the US by 2100 compared to the 2000s due to increasing drought alone. Drought thus poses an important aspect of climate change penalty on air quality, and a better prediction of such effects would require improvements in model processes.

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“…We choose this approach for our model simulation of BrC because relationships between the absorption of OA and the BC / OA ratio have been confirmed by field measurements (X. Gilardoni et al, 2016). For SOA, we assume that only aromatic SOA absorbs light since experiments show most light-absorbing SOA is related to aromatic carbonyls (Jaoui et al, 2008;Desyaterik et al, 2013) and since absorption from biogenic SOA in the field (in the same region and years studied here) has been found to be negligible compared to even mild biomass burning influence (Washenfelder et al, 2015).…”

Section: Treatment Of Brc Optical Propertiesmentioning

confidence: 99%

“…In laboratory studies, the absorption of BrC is found to both increase during the formation or chemical aging of certain types of OA and decrease during oxidation or photolysis (Zhong and Jang, 2011;Flores et al, 2014;Lee et al, 2014;Liu et al, 2016). Field studies provide evidence that BrC may be formed in clouds or during convective transport, due to aqueous-phase chemistry or condensation (Gilardoni et al, 2016;Zhang et al, 2017). Observations also indicate that biomass burning BrC absorption decreases with photochemical aging with a lifetime of ∼ 1 day (Forrister et al, 2015;.…”

mentioning

confidence: 95%

Exploring the observational constraints on the simulation of brown carbon

et al. 2018

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Abstract. Organic aerosols (OA) that strongly absorb solar radiation in the near-UV are referred to as brown carbon (BrC). The sources, evolution, and optical properties of BrC remain highly uncertain and contribute significantly to uncertainty in the estimate of the global direct radiative effect (DRE) of aerosols. Previous modeling studies of BrC optical properties and DRE have been unable to fully evaluate model performance due to the lack of direct measurements of BrC absorption. In this study, we develop a global model simulation (GEOS-Chem) of BrC and test it against BrC absorption measurements from two aircraft campaigns in the continental US (SEAC 4 RS and DC3). To the best of our knowledge, this is the first study to compare simulated BrC absorption with direct aircraft measurements. We show that BrC absorption properties estimated based on previous laboratory measurements agree with the aircraft measurements of freshly emitted BrC absorption but overestimate aged BrC absorption. In addition, applying a photochemical scheme to simulate bleaching/degradation of BrC improves model skill. The airborne observations are therefore consistent with a mass absorption coefficient (MAC) of freshly emitted biomass burning OA of 1.33 m 2 g −1 at 365 nm coupled with a 1-day whitening e-folding time. Using the GEOS-Chem chemical transport model integrated with the RRTMG radiative transfer model, we estimate that the top-of-the-atmosphere allsky direct radiative effect (DRE) of OA is −0.344 Wm −2 , 10 % higher than that without consideration of BrC absorption. Therefore, our best estimate of the absorption DRE of BrC is +0.048 Wm −2 . We suggest that the DRE of BrC has been overestimated previously due to the lack of observational constraints from direct measurements and omission of the effects of photochemical whitening.

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Direct observation of aqueous secondary organic aerosol from biomass-burning emissions

Cited by 291 publications

References 79 publications

Biogenic, urban, and wildfire influences on the molecular composition of dissolved organic compounds in cloud water

Biogenic, urban, and wildfire influences on the molecular composition of dissolved organic compounds in cloud water

Adverse effects of increasing drought on air quality via natural processes

Exploring the observational constraints on the simulation of brown carbon

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