The mass loading and composition of atmospheric particles are important in determining their climate and health effects, and are typically measured by filter sampling. However, particle sampling ...under ambient conditions can lead to a shift in the size cut-off threshold induced by hygroscopic growth, and the influence of this on measurement of particle loading and composition has not been adequately quantified. Here, we propose a method to assess this influence based on κ-Köhler theory. A global perspective is presented based on previously reported annual climatological values of hygroscopic properties, meteorological parameters and particle volume size distributions. Measurements at background sites in Europe may be more greatly influenced by the cut-off shift than those from other continents, with a median influence of 10–20% on the total mass of sampled particles. However, the influence is generally much smaller (<7%) at urban sites, and is negligible for dust and particles in the Arctic. Sea-salt particles experience the largest influence (median value ∼50%), resulting from their large size, high hygroscopicity and the high relative humidity (RH) in marine air-masses. We estimate a difference of ∼30% in this influence of sea-salt particle sampling between relatively dry (RH = 60%) and humid (RH = 90%) conditions. Given the variation in the cut-off shift in different locations and at different times, a consistent consideration of this influence using the approach we introduce here is critical for observational studies of the long-term and spatial distribution of particle loading and composition, and crucial for robust validation of aerosol modules in modelling studies.
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•Hygroscopic growth leads to a shift in the size of dry particles cut off by impactors during sampling.•We propose a method to assess this influence on aerosol measurements, quantifying its global importance for the first time.•Observational comparison and model validation must account for the large temporal and spatial variations in this influence.
We present ship-borne and land-based measurements of carbohydrate concentrations and patterns in (i) bulk seawater, (ii) sea surface microlayer (SML), and (iii) atmospheric size-resolved aerosol ...particles (0.05–10 μm) collected in the Western Antarctic Peninsula. In seawater, we find higher combined carbohydrates (CCHO) in both the particulate (PCCHO, 13–248 μg L–1) and dissolved (DCCHO, 14–294 μg L–1) phases than dissolved free carbohydrates (DFCHO, 1.0–17 μg L–1). Moderate enrichment factors are found in the SML samples (median EFSML = 1.4 for PCCHO, DCCHO, and DFCHO). In PM10 atmospheric particles, combined carbohydrates (CCHOaer,PM10 0.2–11.3 ng m–3) were preferably found in particles of two size modes (0.05–0.42 and 1.2–10 μm) and strongly correlated with Na+ aer,PM10 and wind speed, hence suggesting oceanic emission as their primary source. In contrast to SML samples, very high enrichment factors for CCHOaer relative to the bulk water (EFaer) were estimated for supermicron (20–4000) and submicron (40–167 000) particles. Notably, the relative atmospheric aerosol monosaccharide compositions strongly differed from the ones sampled in seawater. The prevalence of bacterial monosaccharides (muramic acid, glucosamine) in aerosol particles allows us to suggest a selective consumption and release of polysaccharides by bacteria in the atmosphere. Our results highlight the need to evaluate the role of different ecosystems as aerosol sources around Antarctica.
Deposition of atmospheric constituents - either gas phase or particulate - onto urban impervious surfaces gives rise to a thin “urban grime” film. The area exposed by these impervious surfaces in a ...typical urban environment is comparable to, or greater than, that of particles present in the urban boundary layer; however, it is largely overlooked as a site for heterogeneous reactions. Here we present the results of a field campaign to determine and compare the chemical composition of urban grime and of particles collected simultaneously during the autumn of 2014 at an urban site in central Leipzig, Germany. We see dramatically reduced ammonium and nitrate levels in the film as compared to particles, suggesting a significant loss of ammonium nitrate, thus enhancing the mobility of these species in the environment. Nitrate levels are 10% lower for films exposed to sunlight compared to those that were shielded from direct sun, indicating a possible mechanism for recycling nitrate anion to reactive nitrogen species. Finally, chloride levels in the film suggest that urban grime could represent an unrecognized source of continental chloride available for ClNO2 production even in times of low particulate chloride. Such source and recycling processes could prove to be important to local and regional air quality.
Particulate emissions from crop residue burning decrease the air quality as well as influence aerosol radiative properties on a regional scale. The North China Plain (NCP) is known for the large ...scale biomass burning (BB) of field residues, which often results in heavy haze pollution episodes across the region. We have been able to capture a unique BB episode during the international CAREBeijing-NCP intensive field campaign in Wangdu in the NCP (38.6°N, 115.2°E) from June to July 2014. It was found that aerosol particles originating from this BB event showed a significantly different mixing state compared with clean and non-BB pollution episodes. BB originated particles showed a narrower probability density function (PDF) of shrink factor (SF). And the maximum was found at shrink factor of 0.6, which is higher than in other episodes. The non-volatile particle number fraction during the BB episode decreased to 3% and was the lowest measured value compared to all other predefined episodes. To evaluate the influence of particle mixing state on aerosol single scattering albedo (SSA), SSA at different RHs was simulated using the measured aerosol physical-chemical properties. The differences between the calculated SSA for biomass burning, clean and pollution episodes are significant, meaning that the variation of SSA in different pollution conditions needs to be considered in the evaluation of aerosol direct radiative effects in the NCP. And the calculated SSA was found to be quite sensitive on the mixing state of BC, especially at low-RH condition. The simulated SSA was also compared with the measured values. For all the three predefined episodes, the measured SSA are very close to the calculated ones with assumed mixing states of homogeneously internal and core-shell internal mixing, indicating that both of the conception models are appropriate for the calculation of ambient SSA in the NCP.
•Biomass burning aerosol particles are moderately volatile and mixed internally.•Particle hygroscopicity did not change during biomass burning.•Single scattering albedo is sensitive to particle mixing state especially during biomass burning.
Measurements of atmospheric organic particle composition at higher altitudes are scarce. The present study discusses concentrations and sources of PM and organic constituents based on winter-time ...observations at Mount Tai and aircraft measurements above the North China Plain (NCP). For PM2.5 at the mountain site, concentrations up to 94 μg m–3 were measured. Correlations with surrounding cities indicated that, despite an observed boundary layer height below the sampling altitude (1534 m asl), polluted air masses from the plain ascended to the mountaintop, possibly due to orographic effects. Organic constituents showed mean concentrations ranging from ∼1 ng m–3 for terpene-derived acids and some branched or unsaturated dicarboxylic acids but could reach up to ∼100 ng m–3 for oxalic acid. A cluster heatmap revealed correlational relationships between the compounds that originate from sources, including traffic, combustion of coal, waste, and biomass as well as secondary formation. Average concentrations of most short-chain organic acids taken in the general upwind direction of Mount Tai at mean flight altitudes of ∼4000 m averaged 10–25% of the mountain ones outside haze periods, suggesting that chemical formation during high-altitude transport could have occurred. One flight sample showed high concentrations of up to 180 ng m–3 for oxalic acid, which is comparable to mountain haze periods, corroborating earlier observations of elevated pollution layers in the area even at such altitudes. CAPRAM multiphase modeling reproduced selected mountain concentrations of malonic and succinic acids reasonably well, while an initial underestimation of oxalic acid could be reduced by including salt formation and thereby enhanced phase partitioning. Overall, this study addresses observational gaps at high altitudes over the NCP and suggests processes and sources that might also be relevant in other regions.
Fine particulate matter (PM2.5) samples collected at Mount
(Mt.) Tai in the North China Plain during summer 2014 were analyzed for
dicarboxylic acids and related compounds (oxocarboxylic acids and ...α-dicarbonyls) (DCRCs). The total concentration of DCRCs was 1050±580
and 1040±490 ng m−3 during the day and night, respectively.
Although these concentrations were about 2 times lower than similar
measurements in 2006, the concentrations reported here were about 1–13 times
higher than previous measurements in other major cities in the world.
Molecular distributions of DCRCs revealed that oxalic acid (C2) was the
dominant species (50 %), followed by succinic acid (C4) (12 %)
and malonic acid (C3) (8 %). WRF modeling revealed that Mt. Tai was
mostly in the free troposphere during the campaign and long-range transport
was a major factor governing the distributions of the measured compounds at
Mt. Tai. A majority of the samples (79 %) had comparable concentrations
during the day and night, with their day–night concentration ratios between
0.9 and 1.1. Multi-day transport was considered an important reason for the
similar concentrations. Correlation analyses of DCRCs and their gas
precursors and between C2 and sulfate indicated precursor emissions and
aqueous-phase oxidations during long-range transport also likely play an
important role, especially during the night. Source identification indicated
that anthropogenic activities followed by photochemical aging accounted for
about 60 % of the total variance and were the dominant source at Mt. Tai.
However, biomass burning was only important during the first half of the
measurement period. Measurements of potassium (K+) and DCRCs were about
2 times higher than those from the second half of the measurement period. The
concentration of levoglucosan, a biomass burning tracer, decreased by about
80 % between 2006 and 2014, indicating that biomass burning may have
decreased between 2006 and 2014.
Abstract The Aerosol, Clouds and Trace Gases Research Infrastructure (ACTRIS) officially became the 33rd European Research Infrastructure Consortium (ERIC) on 25 April 2023 with the support of 17 ...founding member and observer countries. As a pan-European legal organization, ACTRIS ERIC will coordinate the provision of data and data products on short-lived atmospheric constituents and clouds relevant to climate and air pollution over the next 15–20 years. ACTRIS was designed more than a decade ago, and its development was funded at national and European levels. It was included in the European Strategy Forum on Research Infrastructures (ESFRI) roadmap in 2016 and, subsequently, in the national infrastructure roadmaps of European countries. It became a landmark of the ESFRI roadmap in 2021. The purpose of this paper is to describe the mission of ACTRIS, its added value to the community of atmospheric scientists, providing services to academia as well as the public and private sectors, and to summarize its main achievements. The present publication serves as a reference document for ACTRIS, its users, and the scientific community as a whole. It provides the reader with relevant information and an overview on ACTRIS governance and services, as well as a summary of the main scientific achievements of the last 20 years. The paper concludes with an outlook on the upcoming challenges for ACTRIS and the strategy for its future evolution.
The Aerosol, Clouds and Trace Gases Research Infrastructure (ACTRIS) officially became the 33 rd European Research Infrastructure Consortium (ERIC) on April 25, 2023 with the support of 17 founding ...member and observer countries. As a pan-European legal organization, ACTRIS ERIC will coordinate the provision of data and data products on short-lived atmospheric constituents and clouds relevant to climate and air pollution over the next 15-20 years. ACTRIS was designed more than a decade ago, and its development was funded at national and European levels. It was included in the European Strategy Forum on Research Infrastructures (ESFRI) Roadmap in 2016 and subsequently, in the national infrastructure roadmaps of European countries. It became a landmark of the ESFRI roadmap in 2021. The purpose of this paper is to describe the mission of ACTRIS, its added value to the community of atmospheric scientists, providing services to academia as well as the public and private sectors, and to summarize its main achievements. The present publication serves as a reference document for ACTRIS, its users and the scientific community as a whole. It provides the reader with relevant information and an overview on ACTRIS governance and services, as well as a summary of the main scientific achievements of the last 20 years. The paper concludes with an outlook on the upcoming challenges for ACTRIS and the strategy for its future evolution.
Abstract The Aerosol, Clouds and Trace Gases Research Infrastructure (ACTRIS) officially became the 33 rd European Research Infrastructure Consortium (ERIC) on April 25, 2023 with the support of 17 ...founding member and observer countries. As a pan-European legal organization, ACTRIS ERIC will coordinate the provision of data and data products on short-lived atmospheric constituents and clouds relevant to climate and air pollution over the next 15-20 years. ACTRIS was designed more than a decade ago, and its development was funded at national and European levels. It was included in the European Strategy Forum on Research Infrastructures (ESFRI) Roadmap in 2016 and subsequently, in the national infrastructure roadmaps of European countries. It became a landmark of the ESFRI roadmap in 2021. The purpose of this paper is to describe the mission of ACTRIS, its added value to the community of atmospheric scientists, providing services to academia as well as the public and private sectors, and to summarize its main achievements. The present publication serves as a reference document for ACTRIS, its users and the scientific community as a whole. It provides the reader with relevant information and an overview on ACTRIS governance and services, as well as a summary of the main scientific achievements of the last 20 years. The paper concludes with an outlook on the upcoming challenges for ACTRIS and the strategy for its future evolution.
Size-segregated particle samples were collected in October 2004 during the Program of Regional Integrated Experiments of Air Quality over Pearl River Delta 2004 (PRIDE-PRD2004) at the Xinken site on ...the mouth of the Pearl River. The approach of the PRIDE campaign included simultaneous measurements of gaseous pollutants as well as physical and chemical characterization of particles to realize the regional pollution status and to improve the understanding of atmospheric processes in the PRD region Zhang, Y.H., Hu, M., Zhong, L.J., Wiedensohler, A., Liu, S., Andreae, M., Wang, W., Fan, M., 2008. Regional integrated experiments of air quality over Pearl River Delta 2004: Overview. Atmospheric Environment, this issue, doi:10.1016/j.atmosenv.2008.03.025. Results of optical measurements were already published Cheng, Y. F., Eichler, H., Wiedensohler, A., Heintzenberg, J., Zhang, Y. H., Hu, M., Herrmann, H., Zeng, L. M., Liu, S., Gnauk, T., Brüggemann, E., He, L. Y., 2006. Mixing state of elemental carbon and non-light-absorbing components derived from in situ particle optical properties at Xinken in Pearl River Delta of China. Journal of Geophysical Research 111, D20204, doi:10.1029/2005JD006929.
A total of eight daytime and nighttime size-segregated samples classified into continental and coastal trajectories were analysed for mass concentration, organic and elemental carbon (OC/EC), dicarboxylic acids (DCAs), alkanes and polycyclic aromatic hydrocarbons (PAHs). Comparisons of day- and nighttime as well as continental and coastal samples were carried out for every component in all considered particle size classes. Measured concentrations for all particle components and significant concentration differences for day/night or continental/coastal samples will be discussed in detail and used for a rough source assignment.
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