Change in global aerosol composition since preindustrial times

Abstract. To elucidate human induced changes of aerosol load and composition in the atmosphere, a coupled aerosol and gas-phase chemistry transport model of the troposphere and lower stratosphere has been used. This is the first 3-d modeling study that focuses on aerosol chemical composition change since preindustrial times considering the secondary organic aerosol formation together with all other main aerosol components including nitrate. In particular, we evaluate non-sea-salt sulfate (nss-SO4=), ammonium (NH4+), nitrate (NO3-), black carbon (BC), sea-salt, dust, primary and secondary organics (POA and SOA) with a focus on the importance of secondary organic aerosols. Our calculations show that the aerosol optical depth (AOD) has increased by about 21% since preindustrial times. This enhancement of AOD is attributed to a rise in the atmospheric load of BC, nss-SO4=, NO3-, POA and SOA by factors of 3.3, 2.6, 2.7, 2.3 and 1.2, respectively, whereas we assumed that the natural dust and sea-salt sources remained constant. The nowadays increase in carbonaceous aerosol loading is dampened by a 34–42% faster conversion of hydrophobic to hydrophilic carbonaceous aerosol leading to higher removal rates. These changes between the various aerosol components resulted in significant modifications of the aerosol chemical composition. The relative importance of the various aerosol components is critical for the aerosol climatic effect, since atmospheric aerosols behave differently when their chemical composition changes. According to this study, the aerosol composition changed significantly over the different continents and with height since preindustrial times. The presence of anthropogenically emitted primary particles in the atmosphere facilitates the condensation of the semi-volatile species that form SOA onto the aerosol phase, particularly in the boundary layer. The SOA burden that is dominated by the natural component has increased by 24% while its contribution to the AOD has increased by 11%. The increase in oxidant levels and preexisting aerosol mass since preindustrial times is the reason of the burden change, since emissions have not changed significantly. The computed aerosol composition changes translate into about 2.5 times more water associated with non sea-salt aerosol. Additionally, aerosols contain 2.7 times more inorganic components nowadays than during the preindustrial times. We find that the increase in emissions of inorganic aerosol precursors is much larger than the corresponding aerosol increase, reflecting a non-linear atmospheric response.

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Characterization of aerosol chemical composition with aerosol mass spectrometry in Central Europe: an overview

Atmospheric Chemistry and Physics ◽

10.5194/acp-10-10453-2010 ◽

2010 ◽

Vol 10 (21) ◽

pp. 10453-10471 ◽

Cited By ~ 208

Author(s):

V. A. Lanz ◽

A. S. H. Prévôt ◽

M. R. Alfarra ◽

S. Weimer ◽

C. Mohr ◽

...

Keyword(s):

Mass Spectrometry ◽

Chemical Composition ◽

Organic Aerosol ◽

Volatile Fraction ◽

Aerosol Composition ◽

Aerosol Mass ◽

Aerosol Mass Spectrometry ◽

Field Campaigns ◽

Alpine Valleys ◽

Aerosol Chemical Composition

Abstract. Real-time measurements of non-refractory submicron aerosols (NR-PM1) were conducted within the greater Alpine region (Switzerland, Germany, Austria, France and Liechtenstein) during several week-long field campaigns in 2002–2009. This region represents one of the most important economic and recreational spaces in Europe. A large variety of sites was covered including urban backgrounds, motorways, rural, remote, and high-alpine stations, and also mobile on-road measurements were performed. Inorganic and organic aerosol (OA) fractions were determined by means of aerosol mass spectrometry (AMS). The data originating from 13 different field campaigns and the combined data have been utilized for providing an improved temporal and spatial data coverage. The average mass concentration of NR-PM1 for the different campaigns typically ranged between 10 and 30 μg m−3. Overall, the organic portion was most abundant, ranging from 36% to 81% of NR-PM1. Other main constituents comprised ammonium (5–15%), nitrate (8–36%), sulfate (3–26%), and chloride (0–5%). These latter anions were, on average, fully neutralized by ammonium. As a major result, time of the year (winter vs. summer) and location of the site (Alpine valleys vs. Plateau) could largely explain the variability in aerosol chemical composition for the different campaigns and were found to be better descriptors for aerosol composition than the type of site (urban, rural etc.). Thus, a reassessment of classifications of measurements sites might be considered in the future, possibly also for other regions of the world. The OA data was further analyzed using positive matrix factorization (PMF) and the multi-linear engine ME (factor analysis) separating the total OA into its underlying components, such as oxygenated (mostly secondary) organic aerosol (OOA), hydrocarbon-like and freshly emitted organic aerosol (HOA), as well as OA from biomass burning (BBOA). OOA was ubiquitous, ranged between 36% and 94% of OA, and could be separated into a low-volatility and a semi-volatile fraction (LV-OOA and SV-OOA) for all summer campaigns at low altitude sites. Wood combustion (BBOA) accounted for a considerable fraction during wintertime (17–49% OA), particularly in narrow Alpine valleys BBOA was often the most abundant OA component. HOA/OA ratios were comparatively low for all campaigns (6–16%) with the exception of on-road, mobile measurements (23%) in the Rhine Valley. The abundance of the aerosol components and the retrievability of SV-OOA and LV-OOA are discussed in the light of atmospheric chemistry and physics.

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Size-resolved aerosol composition and link to hygroscopicity at a forested site in Colorado

Atmospheric Chemistry and Physics Discussions ◽

10.5194/acpd-13-23817-2013 ◽

2013 ◽

Vol 13 (9) ◽

pp. 23817-23843 ◽

Cited By ~ 2

Author(s):

E. J. T. Levin ◽

A. J. Prenni ◽

B. Palm ◽

D. Day ◽

P. Campuzano-Jost ◽

...

Keyword(s):

Chemical Composition ◽

Cloud Condensation Nuclei ◽

Cloud Droplet ◽

Large Mass ◽

Aerosol Composition ◽

Aerosol Mass Spectrometer ◽

Aerosol Mass ◽

Mass Fractions ◽

Aerosol Hygroscopicity ◽

Aerosol Chemical Composition

Abstract. Aerosol hygroscopicity describes the ability of a particle to take up water and form a cloud droplet. Modeling studies have shown sensitivity of precipitation-producing cloud systems to the availability of aerosol particles capable of serving as cloud condensation nuclei (CCN), and hygroscopicity is a key parameter controlling the number of available CCN. Continental aerosol is typically assumed to have a representative hygroscopicity parameter, κ, of 0.3; however, in remote locations this value can be lower due to relatively large mass fractions of organic components. To further our understanding of aerosol properties in remote areas, we measured size-resolved aerosol chemical composition and hygroscopicity in a forested, mountainous site in Colorado during the six-week BEACHON-RoMBAS campaign. This campaign followed a year-long measurement period at this site, and results from the intensive campaign shed light on the previously reported seasonal cycle in aerosol hygroscopicity. New particle formation events were observed routinely at this site and nucleation mode composition measurements indicated that the newly formed particles were predominantly organic. These events likely contribute to the dominance of organic species at smaller sizes, where aerosol organic mass fractions of non-refractory components were between 70–90%. Corresponding aerosol hygroscopicity was observed to range from κ = 0.15–0.22, with hygroscopicity increasing with particle size. Aerosol chemical composition measured by an Aerosol Mass Spectrometer and calculated from hygroscopicity measurements agreed very well during the intensive study with an assumed value of κorg = 0.13 resulting in the best agreement.

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Size-resolved aerosol composition and its link to hygroscopicity at a forested site in Colorado

Atmospheric Chemistry and Physics ◽

10.5194/acp-14-2657-2014 ◽

2014 ◽

Vol 14 (5) ◽

pp. 2657-2667 ◽

Cited By ~ 48

Author(s):

E. J. T. Levin ◽

A. J. Prenni ◽

B. B. Palm ◽

D. A. Day ◽

P. Campuzano-Jost ◽

...

Keyword(s):

Chemical Composition ◽

Cloud Condensation Nuclei ◽

Rocky Mountain ◽

Cloud Droplet ◽

Large Mass ◽

Aerosol Composition ◽

Aerosol Mass ◽

Mass Fractions ◽

Aerosol Hygroscopicity ◽

Aerosol Chemical Composition

Abstract. Aerosol hygroscopicity describes the ability of a particle to take up water and form a cloud droplet. Modeling studies have shown sensitivity of precipitation-producing cloud systems to the availability of aerosol particles capable of serving as cloud condensation nuclei (CCN), and hygroscopicity is a key parameter controlling the number of available CCN. Continental aerosol is typically assumed to have a representative hygroscopicity parameter, κ, of 0.3; however, in remote locations this value can be lower due to relatively large mass fractions of organic components. To further our understanding of aerosol properties in remote areas, we measured size-resolved aerosol chemical composition and hygroscopicity in a forested, mountainous site in Colorado during the six-week BEACHON-RoMBAS (Bio-hydro-atmosphere interactions of Energy, Aerosols, Carbon, H2O, Organics and Nitrogen–Rocky Mountain Biogenic Aerosol Study) campaign. This campaign followed a year-long measurement period at this site, and results from the intensive campaign shed light on the previously reported seasonal cycle in aerosol hygroscopicity. New particle formation events were observed routinely at this site and nucleation mode composition measurements indicated that the newly formed particles were predominantly organic. These events likely contribute to the dominance of organic species at smaller sizes, where aerosol organic mass fractions were between 70 and 90%. Corresponding aerosol hygroscopicity was observed to be in the range κ = 0.15–0.22, with hygroscopicity increasing with particle size. Aerosol chemical composition measured by an aerosol mass spectrometer and calculated from hygroscopicity measurements agreed very well during the intensive study, with an assumed value of κorg = 0.13 resulting in the best agreement.

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Change in global aerosol composition since preindustrial times

Atmospheric Chemistry and Physics ◽

10.5194/acp-6-5143-2006 ◽

2006 ◽

Vol 6 (12) ◽

pp. 5143-5162 ◽

Cited By ~ 133

Author(s):

K. Tsigaridis ◽

M. Krol ◽

F. J. Dentener ◽

Y. Balkanski ◽

J. Lathière ◽

...

Keyword(s):

Lower Stratosphere ◽

Transport Model ◽

Organic Aerosol ◽

Sea Salt ◽

Aerosol Formation ◽

Aerosol Composition ◽

Chemistry Transport Model ◽

Gas Phase Chemistry ◽

Induced Changes ◽

Phase Chemistry

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Changes in organic aerosol composition with aging inferred from aerosol mass spectra

Atmospheric Chemistry and Physics ◽

10.5194/acp-11-6465-2011 ◽

2011 ◽

Vol 11 (13) ◽

pp. 6465-6474 ◽

Cited By ~ 323

Author(s):

N. L. Ng ◽

M. R. Canagaratna ◽

J. L. Jimenez ◽

P. S. Chhabra ◽

J. H. Seinfeld ◽

...

Keyword(s):

Chemical Composition ◽

Organic Aerosols ◽

Organic Aerosol ◽

Aerosol Formation ◽

Aerosol Composition ◽

Bond Breakage ◽

Aerosol Mass ◽

Physical Mixing ◽

Chamber Studies ◽

Van Krevelen Diagram

Abstract. Organic aerosols (OA) can be separated with factor analysis of aerosol mass spectrometer (AMS) data into hydrocarbon-like OA (HOA) and oxygenated OA (OOA). We develop a new method to parameterize H:C of OOA in terms of f43 (ratio of m/z 43, mostly C2H3O+, to total signal in the component mass spectrum). Such parameterization allows for the transformation of large database of ambient OOA components from the f44 (mostly CO2+, likely from acid groups) vs. f43 space ("triangle plot") (Ng et al., 2010) into the Van Krevelen diagram (H:C vs. O:C) (Van Krevelen, 1950). Heald et al. (2010) examined the evolution of total OA in the Van Krevelen diagram. In this work total OA is deconvolved into components that correspond to primary (HOA and others) and secondary (OOA) organic aerosols. By deconvolving total OA into different components, we remove physical mixing effects between secondary and primary aerosols which allows for examination of the evolution of OOA components alone in the Van Krevelen space. This provides a unique means of following ambient secondary OA evolution that is analogous to and can be compared with trends observed in chamber studies of secondary organic aerosol formation. The triangle plot in Ng et al. (2010) indicates that f44 of OOA components increases with photochemical age, suggesting the importance of acid formation in OOA evolution. Once they are transformed with the new parameterization, the triangle plot of the OOA components from all sites occupy an area in Van Krevelen space which follows a ΔH:C/ΔO:C slope of ~ −0.5. This slope suggests that ambient OOA aging results in net changes in chemical composition that are equivalent to the addition of both acid and alcohol/peroxide functional groups without fragmentation (i.e. C-C bond breakage), and/or the addition of acid groups with fragmentation. These results provide a framework for linking the bulk aerosol chemical composition evolution to molecular-level studies.

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Properties of aerosols and formation mechanisms over southern China during the monsoon season

10.5194/acp-2016-390 ◽

2016 ◽

Author(s):

Weihua Chen ◽

Xuemei Wang ◽

Jason Blake Cohen ◽

Shengzhen Zhou ◽

Zhisheng Zhang ◽

...

Keyword(s):

Aqueous Phase ◽

Atmospheric Aerosols ◽

Transport Model ◽

Atmospheric Transport ◽

Southern China ◽

Monsoon Season ◽

Sea Salt ◽

Urban Site ◽

Chemical Components ◽

Formation Mechanisms

Abstract. Measurements of size-resolved aerosols from 0.25 to 18 μm were conducted at three sites (urban, suburban and background sites) and used in tandem with an atmospheric transport model to study the size distribution and formation of atmospheric aerosols in southern China during the monsoon season (May–June) in 2010. The mass distribution showed the majority of chemical components were found in the smaller size bins (< 2.5 μm). Sulfate, was found to be strongly correlated with aerosol water, and anti-correlated with atmospheric SO2, hinting at aqueous-phase reactions being the main formation pathway. Nitrate was the only major species that showed a bi-modal distribution at the urban site, and was dominated by the coarse mode in the other two sites, suggesting that an important component of nitrate formation is chloride depletion of sea salt transported from the South China Sea. In addition to these aqueous-phase reactions and interactions with sea salt aerosols, new particle formation, chemical aging, and long-range transport from upwind urban or biomass burning regions were also found to be important in at least some of the sights on some of the days. This work therefore summarizes the different mechanisms that significantly impact the aerosol chemical composition during the Monsoon over southern China.

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Towards an online-coupled chemistry-climate model: evaluation of trace gases and aerosols in COSMO-ART

Geoscientific Model Development ◽

10.5194/gmd-4-1077-2011 ◽

2011 ◽

Vol 4 (4) ◽

pp. 1077-1102 ◽

Cited By ~ 63

Author(s):

C. Knote ◽

D. Brunner ◽

H. Vogel ◽

J. Allan ◽

A. Asmi ◽

...

Keyword(s):

Chemical Composition ◽

Size Distribution ◽

Urban Areas ◽

Climate Model ◽

Transport Model ◽

Climate Impacts ◽

Chemistry Transport Model ◽

Pm2.5 And Pm10 ◽

Phase Chemistry ◽

Aerosol Chemical Composition

Abstract. The online-coupled, regional chemistry transport model COSMO-ART is evaluated for periods in all seasons against several measurement datasets to assess its ability to represent gaseous pollutants and ambient aerosol characteristics over the European domain. Measurements used in the comparison include long-term station observations, satellite and ground-based remote sensing products, and complex datasets of aerosol chemical composition and number size distribution from recent field campaigns. This is the first time these comprehensive measurements of aerosol characteristics in Europe are used to evaluate a regional chemistry transport model. We show a detailed analysis of the simulated size-resolved chemical composition under different meteorological conditions. Mean, variability and spatial distribution of the concentrations of O3 and NOx are well reproduced. SO2 is found to be overestimated, simulated PM2.5 and PM10 levels are on average underestimated, as is AOD. We find indications of an overestimation of shipping emissions. Time evolution of aerosol chemical composition is captured, although some biases are found in relative composition. Nitrate aerosol components are on average overestimated, and sulfates underestimated. The accuracy of simulated organics depends strongly on season and location. While strongly underestimated during summer, organic mass is comparable in spring and autumn. We see indications for an overestimated fractional contribution of primary organic matter in urban areas and an underestimation of SOA at many locations. Aerosol number concentrations compare well with measurements for larger size ranges, but overestimations of particle number concentration with factors of 2–5 are found for particles smaller than 50 nm. Size distribution characteristics are often close to measurements, but show discrepancies at polluted sites. Suggestions for further improvement of the modeling system consist of the inclusion of a revised secondary organic aerosols scheme, aqueous-phase chemistry and improved aerosol boundary conditions. Our work sets the basis for subsequent studies of aerosol characteristics and climate impacts with COSMO-ART, and highlights areas where improvements are necessary for current regional modeling systems in general.

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Aerosol Chemical Composition in Cloud Events by High Resolution Time-of-Flight Aerosol Mass Spectrometry

Environmental Science & Technology ◽

10.1021/es302889w ◽

2013 ◽

Vol 47 (6) ◽

pp. 2645-2653 ◽

Cited By ~ 28

Author(s):

Liqing Hao ◽

Sami Romakkaniemi ◽

Aki Kortelainen ◽

Antti Jaatinen ◽

Harri Portin ◽

...

Keyword(s):

Mass Spectrometry ◽

Chemical Composition ◽

High Resolution ◽

Time Of Flight ◽

Resolution Time ◽

Aerosol Mass ◽

Aerosol Mass Spectrometry ◽

Aerosol Chemical Composition

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Impact of Aerosol-Cloud Cycling on Aqueous Secondary Organic Aerosol Formation

Atmosphere ◽

10.3390/atmos10110666 ◽

2019 ◽

Vol 10 (11) ◽

pp. 666 ◽

Cited By ~ 3

Author(s):

William G. Tsui ◽

Joseph L. Woo ◽

V. Faye McNeill

Keyword(s):

Atmospheric Aerosols ◽

Organic Material ◽

Organic Aerosol ◽

Time Of Day ◽

Aerosol Formation ◽

Atmospheric Models ◽

Cloud Processing ◽

Aerosol Mass ◽

Phase Chemistry ◽

The Impact

Chemical processing of organic material in aqueous atmospheric aerosols and cloudwater is known to form secondary organic aerosols (SOA), although the extent to which each of these processes contributes to total aerosol mass is unclear. In this study, we use GAMMA 5.0, a photochemical box model with coupled gas and aqueous-phase chemistry, to consider the impact of aqueous organic reactions in both aqueous aerosols and clouds on isoprene epoxydiol (IEPOX) SOA over a range of pH for both aqueous phases, including cycling between cloud and aerosol within a single simulation. Low pH aqueous aerosol, in the absence of organic coatings or other morphology which may limit uptake of IEPOX, is found to be an efficient source of IEPOX SOA, consistent with previous work. Cloudwater at pH 4 or lower is also found to be a potentially significant source of IEPOX SOA. This phenomenon is primarily attributed to the relatively high uptake of IEPOX to clouds as a result of higher water content in clouds as compared with aerosol. For more acidic cloudwater, the aqueous organic material is comprised primarily of IEPOX SOA and lower-volatility organic acids. Both cloudwater pH and the time of day or sequence of aerosol-to-cloud or cloud-to-aerosol transitions impacted final aqueous SOA mass and composition in the simulations. The potential significance of cloud processing as a contributor to IEPOX SOA production could account for discrepancies between predicted IEPOX SOA mass from atmospheric models and measured ambient IEPOX SOA mass, or observations of IEPOX SOA in locations where mass transfer limitations are expected in aerosol particles.

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Significant contrasts in aerosol acidity between China and the United States

Atmospheric Chemistry and Physics ◽

10.5194/acp-21-8341-2021 ◽

2021 ◽

Vol 21 (10) ◽

pp. 8341-8356

Author(s):

Bingqing Zhang ◽

Huizhong Shen ◽

Pengfei Liu ◽

Hongyu Guo ◽

Yongtao Hu ◽

...

Keyword(s):

United States ◽

Chemical Composition ◽

The United States ◽

Formation Mechanisms ◽

Aerosol Composition ◽

Ph Values ◽

Aerosol Acidity ◽

Aerosol Mass ◽

The Usa ◽

Mass Concentrations

Abstract. Aerosol acidity governs several key processes in aerosol physics and chemistry, thus affecting aerosol mass and composition and ultimately climate and human health. Previous studies have reported aerosol pH values separately in China and the United States (USA), implying different aerosol acidity between these two countries. However, there is debate about whether mass concentration or chemical composition is the more important driver of differences in aerosol acidity. A full picture of the pH difference and the underlying mechanisms responsible is hindered by the scarcity of simultaneous measurements of particle composition and gaseous species, especially in China. Here we conduct a comprehensive assessment of aerosol acidity in China and the USA using extended ground-level measurements and regional chemical transport model simulations. We show that aerosols in China are significantly less acidic than in the USA, with pH values 1–2 units higher. Based on a proposed multivariable Taylor series method and a series of sensitivity tests, we identify major factors leading to the pH difference. Compared to the USA, China has much higher aerosol mass concentrations (gas + particle, by a factor of 8.4 on average) and a higher fraction of total ammonia (gas + particle) in the aerosol composition. Our assessment shows that the differences in mass concentrations and chemical composition play equally important roles in driving the aerosol pH difference between China and the USA – increasing the aerosol mass concentrations (by a factor of 8.4) but keeping the relative component contributions the same in the USA as the level in China increases the aerosol pH by ∼ 1.0 units and further shifting the chemical composition from US conditions to China's that are richer in ammonia increases the aerosol pH by ∼ 0.9 units. Therefore, China being both more polluted than the USA and richer in ammonia explains the aerosol pH difference. The difference in aerosol acidity highlighted in the present study implies potential differences in formation mechanisms, physicochemical properties, and toxicity of aerosol particles in these two countries.

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