Special Issue "Carbonaceous Aerosols in Atmosphere"

A special issue of Atmosphere (ISSN 2073-4433). This special issue belongs to the section "Aerosols".

Deadline for manuscript submissions: closed (15 October 2017).

Special Issue Editors

Guest Editor
Dr. Daniele Contini

Institute of Atmospheric Sciences and Climate, National Research Council, Str. Prv. Lecce-Monteroni km 1.2, 73100 Lecce, Italy
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Interests: atmosphere composition; aerosol sources; receptor models; turbulent fluxes; particle deposition; nucleation
Guest Editor
Prof. Dr. Roberta Vecchi

Department of Physics, Università degli Studi di Milano and National Institute of Nuclear Physics-Milan, via Celoria 16, 20133 Milan, Italy
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Interests: aerosol chemical–physical properties; development of experimental techniques for aerosol characterization; source apportionment by receptor modelling
Guest Editor
Dr. Mar Viana

Institute for Environmental Assessment and Water Research (IDAEA-CSIC), C/Jordi Girona, 18 -26, 08034 Barcelona, Spain
Website | E-Mail
Interests: aerosol geochemistry; indoor and outdoor air quality; source apportionment; personal exposure assessment

Special Issue Information

Dear Colleagues,

Carbonaceous particles suspended in atmosphere have drawn increasing attention in scientific research because of their effects on both climate and human health. Black carbon (BC) is currently an issue, both the local and global scales; it has a primary origin and it is emitted mainly from anthropogenic combustion sources (industrial emissions, road transport, domestic heating). As characterized by strong light absorption, BC particles are largely responsible for positive radiative forcing due to aerosols. In addition, BC has adverse effects on human health, deteriorating air quality in several countries all over the world. Organic carbon (OC) is one of the greatest contributors to particulate matter mass concentrations; it comes from different anthropogenic (combustion processes) and natural (sea-spray, biogenic emissions) sources. A large fraction of OC in the atmosphere has a secondary origin; gas-to-particle conversion processes. Recently, the scientific community has addressed Brown Carbon (BrC), which is a light-absorbing organic compound, of which the characteristics are still largely unknown. Understanding the properties and the dynamics of carbonaceous particles, contributions from main anthropogenic and natural sources, and carbonaceous aerosols transformation in atmosphere is a complex task that needs extensive research. In this Special Issue, we seek to publish papers dealing broadly with the topic of carbonaceous particles in atmosphere, addressing any of the different perspectives, including laboratory studies and measurement protocols, analysis of optical properties and climate effects, source apportionment results, emission inventories and modelling studies, as well as assessments of the health effects and population exposure.

Dr. Daniele Contini
Prof. Dr. Roberta Vecchi
Dr. Mar Viana
Guest Editors

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Keywords

  • elemental and organic carbon

  • black carbon

  • brown carbon

  • chemical characterization of carbonaceous matter

  • BC and BrC optical properties

  • measurement protocols

  • emission inventories

  • source apportionment

  • impact on health and the environment

Published Papers (17 papers)

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Editorial

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Open AccessEditorial
Carbonaceous Aerosols in the Atmosphere
Atmosphere 2018, 9(5), 181; https://doi.org/10.3390/atmos9050181
Received: 7 May 2018 / Revised: 7 May 2018 / Accepted: 8 May 2018 / Published: 10 May 2018
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Abstract
Scientific understanding of the processes involving carbonaceous aerosols in atmosphere is extremely important for both the climate and human health. This explains the increasing scientific interest in characterising these chemical species [1,2].[...] Full article
(This article belongs to the Special Issue Carbonaceous Aerosols in Atmosphere)

Research

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Open AccessArticle
Black Carbon Aerosol in Rome (Italy): Inference of a Long-Term (2001–2017) Record and Related Trends from AERONET Sun-Photometry Data
Atmosphere 2018, 9(3), 81; https://doi.org/10.3390/atmos9030081
Received: 14 October 2017 / Revised: 12 February 2018 / Accepted: 21 February 2018 / Published: 25 February 2018
Cited by 3 | PDF Full-text (14372 KB) | HTML Full-text | XML Full-text | Supplementary Files
Abstract
Surface concentration of black carbon (BC) is a key factor for the understanding of the impact of anthropogenic pollutants on human health. The majority of Italian cities lack long-term measurements of BC concentrations since such a metric is not regulated by EU legislation. [...] Read more.
Surface concentration of black carbon (BC) is a key factor for the understanding of the impact of anthropogenic pollutants on human health. The majority of Italian cities lack long-term measurements of BC concentrations since such a metric is not regulated by EU legislation. This work attempts a long-term (2001–2017) inference of equivalent black carbon (eBC) concentrations in the city of Rome (Italy) based on sun-photometry data. To this end, aerosol light absorption coefficients at the surface are inferred from the ”columnar” aerosol aerosol light absorption coefficient records from the Rome Tor Vergata AERONET sun-photometer. The main focus of this work is to rescale aerosol light absorption columnar data (AERONET) to ground-level BC data. This is done by using values of mixing layer height (MLH) derived from ceilometer measurements and then by converting the absorption into eBC mass concentration through a mass–to–absorption conversion factor, the Mass Absorption Efficiency (MAE). The final aim is to obtain relevant data representative of the BC aerosol at the surface (i.e., in-situ)–so within the MLH– and then to infer a long-term record of “surface” equivalent black carbon mass concentration in Rome. To evaluate the accuracy of this procedure, we compared the AERONET-based results to in-situ measurements of aerosol light absorption coefficients ( α abs) collected during some intensive field campaigns performed in Rome between 2010 and 2017. This analysis shows that different measurement methods, local emissions, and atmospheric conditions (MLH, residual layers) are some of the most important factors influencing differences between inferred and measured α abs. As a general result, ”inferred” and ”measured” α abs resulted to reach quite a good correlation (up to r = 0.73) after a screening procedure that excludes one of the major cause of discrepancy between AERONET inferred and in-situ measured α abs: the presence of highly absorbing aerosol layers at high altitude (e.g., dust), which frequently affects the Mediterranean site of Rome. Long-term trends of “inferred” α abs, eBC, and of the major optical variables that control aerosol’s direct radiative forcing (extinction aerosol optical depth, AODEXT, absorption aerosol optical depth, AODABS, and single scattering albedo, SSA) have been estimated. The Mann-Kendall statistical test associated with Sen’s slope was used to test the data for long-term trends. These show a negative trend for both AODEXT (−0.047/decade) and AODABS (−0.007/decade). The latter converts into a negative trend for the α abs of −5.9 Mm−1/decade and for eBC mass concentration of −0.76 μ g / m 3 /decade. A positive trend is found for SSA (+0.014/decade), indicating that contribution of absorption to extinction is decreasing faster than that of scattering. These long-term trends are consistent with those of other air pollutant concentrations (i.e., PM2.5 and CO) in the Rome area. Despite some limitations, findings of this study fill a current lack in BC observations and may bear useful implications with regard to the improvement of our understanding of the impact of BC on air quality and climate in this Mediterranean urban region. Full article
(This article belongs to the Special Issue Carbonaceous Aerosols in Atmosphere)
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Open AccessArticle
Characteristics of Carbonaceous Aerosol in PM2.5 at Wanzhou in the Southwest of China
Atmosphere 2018, 9(2), 37; https://doi.org/10.3390/atmos9020037
Received: 1 December 2017 / Revised: 18 January 2018 / Accepted: 20 January 2018 / Published: 24 January 2018
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Abstract
Hourly organic carbon (OC) and elemental carbon (EC) concentrations in PM2.5 were measured from June 2013 to May 2014 in Wanzhou, the second largest city in the Chongqing Municipality, in the southwest of China. Results show that the annual average concentrations of [...] Read more.
Hourly organic carbon (OC) and elemental carbon (EC) concentrations in PM2.5 were measured from June 2013 to May 2014 in Wanzhou, the second largest city in the Chongqing Municipality, in the southwest of China. Results show that the annual average concentrations of OC and EC were 13.16 ± 7.98 and 3.12 ± 1.51 μgC·m−3, respectively. Clear seasonal variations of OC and EC concentrations were observed, with their concentrations at minima in summer and maxima in winter. The diel concentration profile of OC and EC presented a bimodal pattern, which was attributed to the cooperative effects of local meteorological conditions and source emissions. The daily average OC/EC ratio ranged from 2.05 to 8.17 with an average of 4.15 for the whole study period. Strong correlations between OC and EC were found in winter and spring, indicating their common sources, while their correlations were poorer in summer and autumn, indicating that the influence of biogenic emissions and secondary organic carbon (SOC) were significant during those seasons. The estimated SOC concentrations were 2.19 ± 1.55, 7.66 ± 5.89, 5.79 ± 3.51, and 3.43 ± 2.26 μgC·m−3, accounting for 29.2%, 52.7%, 27.4%, and 30.5% of total organic carbon in summer, autumn, winter, and spring, respectively. The analysis of back trajectories suggested that high PM2.5, OC, and EC concentrations were associated with air masses originating from or passing over several industrial centers and urban areas in western and northwestern China. Air trajectories from the southeast with short pathways were the dominant trajectories arriving at Wanzhou, indicating that local sources had a big influence on PM2.5, OC, and EC concentrations. Full article
(This article belongs to the Special Issue Carbonaceous Aerosols in Atmosphere)
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Open AccessArticle
Exposure to Black Carbon during Bicycle Commuting–Alternative Route Selection
Atmosphere 2018, 9(1), 21; https://doi.org/10.3390/atmos9010021
Received: 8 December 2017 / Revised: 6 January 2018 / Accepted: 12 January 2018 / Published: 15 January 2018
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Abstract
Traffic air pollution significantly influences cyclists using cycling routes near main roads. We analyze the dependency of black carbon (BC) concentrations in relation to the proximity to their traffic sources. We performed static and mobile measurements of BC using aethalometers at chosen sites [...] Read more.
Traffic air pollution significantly influences cyclists using cycling routes near main roads. We analyze the dependency of black carbon (BC) concentrations in relation to the proximity to their traffic sources. We performed static and mobile measurements of BC using aethalometers at chosen sites and cycling routes in Celje, Slovenia—static measurements at two road-side sites and an urban background site. Mobile measurements were performed simultaneously at an existing cycling route and an alternative route away from the busy roads. BC concentration apportioned to traffic decreases with the distance from the sources on the main road. The exposure of cyclists to BC can be greatly reduced by moving the cycling route away from busy roads, hence we propose an alternative route and show that traffic planning and management should include all modes of transport. Results imply that street intersections along the cycling routes influence the cyclists’ exposure and should be as few as possible when planning cycling routes in urban areas. Full article
(This article belongs to the Special Issue Carbonaceous Aerosols in Atmosphere)
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Open AccessArticle
First Results of the “Carbonaceous Aerosol in Rome and Environs (CARE)” Experiment: Beyond Current Standards for PM10
Atmosphere 2017, 8(12), 249; https://doi.org/10.3390/atmos8120249
Received: 16 October 2017 / Revised: 6 December 2017 / Accepted: 6 December 2017 / Published: 12 December 2017
Cited by 8 | PDF Full-text (13063 KB) | HTML Full-text | XML Full-text | Supplementary Files
Abstract
In February 2017 the “Carbonaceous Aerosol in Rome and Environs (CARE)” experiment was carried out in downtown Rome to address the following specific questions: what is the color, size, composition, and toxicity of the carbonaceous aerosol in the Mediterranean urban background area of [...] Read more.
In February 2017 the “Carbonaceous Aerosol in Rome and Environs (CARE)” experiment was carried out in downtown Rome to address the following specific questions: what is the color, size, composition, and toxicity of the carbonaceous aerosol in the Mediterranean urban background area of Rome? The motivation of this experiment is the lack of understanding of what aerosol types are responsible for the severe risks to human health posed by particulate matter (PM) pollution, and how carbonaceous aerosols influence radiative balance. Physicochemical properties of the carbonaceous aerosol were characterised, and relevant toxicological variables assessed. The aerosol characterisation includes: (i) measurements with high time resolution (min to 1–2 h) at a fixed location of black carbon (eBC), elemental carbon (EC), organic carbon (OC), particle number size distribution (0.008–10 μ m), major non refractory PM1 components, elemental composition, wavelength-dependent optical properties, and atmospheric turbulence; (ii) 24-h measurements of PM10 and PM2.5 mass concentration, water soluble OC and brown carbon (BrC), and levoglucosan; (iii) mobile measurements of eBC and size distribution around the study area, with computational fluid dynamics modeling; (iv) characterisation of road dust emissions and their EC and OC content. The toxicological assessment includes: (i) preliminary evaluation of the potential impact of ultrafine particles on lung epithelia cells (cultured at the air liquid interface and directly exposed to particles); (ii) assessment of the oxidative stress induced by carbonaceous aerosols; (iii) assessment of particle size dependent number doses deposited in different regions of the human body; (iv) PAHs biomonitoring (from the participants into the mobile measurements). The first experimental results of the CARE experiment are presented in this paper. The objective here is to provide baseline levels of carbonaceous aerosols for Rome, and to address future research directions. First, we found that BC and EC mass concentration in Rome are larger than those measured in similar urban areas across Europe (the urban background mass concentration of eBC in Rome in winter being on average 2.6 ± 2.5 μ g · m 3 , mean eBC at the peak level hour being 5.2 (95% CI = 5.0–5.5) μ g · m 3 ). Then, we discussed significant variations of carbonaceous aerosol properties occurring with time scales of minutes, and questioned on the data averaging period used in current air quality standard for PM 10 (24-h). Third, we showed that the oxidative potential induced by aerosol depends on particle size and composition, the effects of toxicity being higher with lower mass concentrations and smaller particle size. Albeit this is a preliminary analysis, findings reinforce the need for an urgent update of existing air quality standards for PM 10 and PM 2.5 with regard to particle composition and size distribution, and data averaging period. Our results reinforce existing concerns about the toxicity of carbonaceous aerosols, support the existing evidence indicating that particle size distribution and composition may play a role in the generation of this toxicity, and remark the need to consider a shorter averaging period (<1 h) in these new standards. Full article
(This article belongs to the Special Issue Carbonaceous Aerosols in Atmosphere)
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Open AccessArticle
Inter-Comparison of Carbon Content in PM2.5 and PM10 Collected at Five Measurement Sites in Southern Italy
Atmosphere 2017, 8(12), 243; https://doi.org/10.3390/atmos8120243
Received: 19 September 2017 / Revised: 28 November 2017 / Accepted: 30 November 2017 / Published: 6 December 2017
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Abstract
A field campaign was performed simultaneously at five measurement sites, having different characteristics, to characterize the spatial distribution of the carbonaceous content in atmospheric aerosol in Southern Italy during the winter season. Organic carbon (OC) and elemental carbon (EC) were measured at urban [...] Read more.
A field campaign was performed simultaneously at five measurement sites, having different characteristics, to characterize the spatial distribution of the carbonaceous content in atmospheric aerosol in Southern Italy during the winter season. Organic carbon (OC) and elemental carbon (EC) were measured at urban (Naples), suburban (Lecce), coastal/marine (Lamezia Terme and Capo Granitola), and remote (Monte Curcio) locations. OC and EC mass concentrations were quantified by the thermal-optical transmission (TOT) method, in 24-h PM10 and PM2.5 samples collected on quartz fiber filters, from 25 November 2015 to 1 January 2016. The different sites showed marked differences in the average concentrations of both carbonaceous species. Typically, OC average levels (±standard deviation) were higher at the sites of Naples (12.8 ± 5.1 and 11.8 ± 4.6 μg/m3) and Lecce (10.7 ± 5.8 and 9.0 ± 4.7 μg/m3), followed by Lamezia Terme (4.3 ± 2.0 and 4.0 ± 1.9 μg/m3), Capo Granitola (2.3 ± 1.2 and 1.7 ± 1.1 μg/m3), and Monte Curcio (0.9 ± 0.3 and 0.9 ± 0.3 μg/m3) in PM10 and PM2.5, respectively. Similarly, EC average levels (±standard deviation) were higher at the urban sites of Naples (2.3 ± 1.1 and 1.8 ± 0.5 μg/m3) and Lecce (1.5 ± 0.8 and 1.4 ± 0.7 μg/m3), followed by Lamezia Terme (0.6 ± 0.3 and 0.6 ± 0.3 μg/m3), Capo Granitola (0.3 ± 0.3 and 0.3 ± 0.2 μg/m3), and Monte Curcio (0.06 ± 0.04 and 0.05 ± 0.03 μg/m3) in PM10 and PM2.5, respectively. An opposite trend was observed for the OC/EC ratios ranging from 6.4 to 15.9 in PM10 and from 6.4 to 15.5 in PM2.5 with lower values in urban sites compared to remote sites. Different OC-EC correlations, 0.36 < R2 < 0.90, were found in four observation sites. This behavior suggests the contributions of similar sources and common atmospheric processes in both fractions. No correlations were observed between OC and EC at the site of Naples. The average secondary organic carbon (SOC) concentrations, quantified using the minimum OC/EC ratio method, ranged from 0.4 to 7.6 μg/m3 in PM10 and from 0.4 to 7.2 μg/m3 in PM2.5, accounting from 37 to 59% of total OC in PM10 and from 40 to 57% in PM2.5 with higher percentages in the urban and suburban sites of Naples and Lecce. Full article
(This article belongs to the Special Issue Carbonaceous Aerosols in Atmosphere)
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Open AccessArticle
Annual Variability of Black Carbon Concentrations Originating from Biomass and Fossil Fuel Combustion for the Suburban Aerosol in Athens, Greece
Atmosphere 2017, 8(12), 234; https://doi.org/10.3390/atmos8120234
Received: 26 October 2017 / Revised: 16 November 2017 / Accepted: 21 November 2017 / Published: 25 November 2017
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Abstract
The objective of this work was to assess the yearly contribution of fossil fuel combustion (BCff) and wood burning (BCwb) to equivalent black carbon (eBC) concentrations, in Athens, Greece. Measurements were conducted at a suburban site from March 2013 [...] Read more.
The objective of this work was to assess the yearly contribution of fossil fuel combustion (BCff) and wood burning (BCwb) to equivalent black carbon (eBC) concentrations, in Athens, Greece. Measurements were conducted at a suburban site from March 2013 to February 2014 and included absorption coefficients at seven wavelengths and PM2.5 chemical composition data for key biomass burning markers, i.e., levoglucosan, potassium (K) and elemental and organic carbon (EC, OC). A well-documented methodology of corrections for aethalometer attenuation coefficients was applied with a resulting annual dataset of derived absorption coefficients for the suburban Athens’ atmospheric aerosol. The Aethalometer model was applied for the source apportionment of eBC. An optimum Ångström exponent for fossil fuel (αff) was found, based on the combined use of the model with levoglucosan data. The measured eBC concentrations were equal to 2.4 ± 1.0 μg m−3 and 1.6 ± 0.6 μg m−3, during the cold and the warm period respectively. The contribution from wood burning was significantly higher during the cold period (21 ± 11%, versus 6 ± 7% in the warm period). BCff displayed a clear diurnal pattern with a morning peak between 8 and 10 a.m. (during morning rush hour) and a second peak during the evening and night hours, due to the shallowing of the mixing layer. Regression analysis between BCwb concentrations and biomass burning markers (levoglucosan, K and OC/EC ratio) supported the validity of the results. Full article
(This article belongs to the Special Issue Carbonaceous Aerosols in Atmosphere)
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Open AccessArticle
A High Resolution Spatiotemporal Model for In-Vehicle Black Carbon Exposure: Quantifying the In-Vehicle Exposure Reduction Due to the Euro 5 Particulate Matter Standard Legislation
Atmosphere 2017, 8(11), 230; https://doi.org/10.3390/atmos8110230
Received: 15 October 2017 / Revised: 11 November 2017 / Accepted: 17 November 2017 / Published: 22 November 2017
Cited by 2 | PDF Full-text (1175 KB) | HTML Full-text | XML Full-text | Supplementary Files
Abstract
Several studies have shown that a significant amount of daily air pollution exposure is inhaled during trips. In this study, car drivers assessed their own black carbon exposure under real-life conditions (223 h of data from 2013). The spatiotemporal exposure of the car [...] Read more.
Several studies have shown that a significant amount of daily air pollution exposure is inhaled during trips. In this study, car drivers assessed their own black carbon exposure under real-life conditions (223 h of data from 2013). The spatiotemporal exposure of the car drivers is modeled using a data science approach, referred to as “microscopic land-use regression” (µLUR). In-vehicle exposure is highly dynamical and is strongly related to the local traffic dynamics. An extensive set of potential covariates was used to model the in-vehicle black carbon exposure in a temporal resolution of 10 s. Traffic was retrieved directly from traffic databases and indirectly by attributing the trips through a noise map as an alternative traffic source. Modeling by generalized additive models (GAM) shows non-linear effects for meteorology and diurnal traffic patterns. A fitted diurnal pattern explains indirectly the complex diurnal variability of the exposure due to the non-linear interaction between traffic density and distance to the preceding vehicles. Comparing the strength of direct traffic attribution and indirect noise map-based traffic attribution reveals the potential of noise maps as a proxy for traffic-related air pollution exposure. An external validation, based on a dataset gathered in 2010–2011, quantifies the exposure reduction inside the vehicles at 33% (mean) and 50% (median). The EU PM Euro 5 PM emission standard (in force since 2009) explains the largest part of the discrepancy between the measurement campaign in 2013 and the validation dataset. The µLUR methodology provides a high resolution, route-sensitive, seasonal and meteorology-sensitive personal exposure estimate for epidemiologists and policy makers. Full article
(This article belongs to the Special Issue Carbonaceous Aerosols in Atmosphere)
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Graphical abstract

Open AccessArticle
Evaluation and Inter-Comparison of Oxygen-Based OC-EC Separation Methods for Radiocarbon Analysis of Ambient Aerosol Particle Samples
Atmosphere 2017, 8(11), 226; https://doi.org/10.3390/atmos8110226
Received: 4 October 2017 / Revised: 11 November 2017 / Accepted: 15 November 2017 / Published: 21 November 2017
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Abstract
Radiocarbon analysis is a widely-used tool for source apportionment of aerosol particles. One of the big challenges of this method, addressed in this work, is to isolate elemental carbon (EC) for 14C analysis. In the first part of the study, we validate [...] Read more.
Radiocarbon analysis is a widely-used tool for source apportionment of aerosol particles. One of the big challenges of this method, addressed in this work, is to isolate elemental carbon (EC) for 14C analysis. In the first part of the study, we validate a two-step method (2stepCIO) to separate total carbon (TC) into organic carbon (OC) and EC against the EUSAAR_2 thermal-optical method regarding the recovered carbon concentrations. The 2stepCIO method is based on the combustion of OC in pure oxygen at two different temperature steps to isolate EC. It is normally used with a custom-built aerosol combustion system (ACS), but in this project, it was also implemented as a thermal protocol on a Sunset OC-EC analyzer. Results for the recovered EC mass concentration showed poor agreement between the 2stepCIO method on the ACS system and on the Sunset analyzer. This indicates that the EC recovery is sensitive not only to the temperature steps, but also to instrument-specific parameters, such as heating rates. We also found that the EUSAAR_2 protocol itself can underestimate the EC concentration on untreated samples compared to water-extracted samples. This is especially so for highly loaded filters, which are typical for 14C analysis. For untreated samples, the EC concentration on long-term filter samples (two to five days sampling time) was 20–45% lower than the sum of EC found on the corresponding 24-h filter samples. For water-extracted filter samples, there was no significant difference between long-term and the sum of daily filter samples. In the second part of this study, the 14C was measured on EC isolated by the 2stepCIO method and compared to methods from two other laboratories. The different methods agree well within their uncertainty estimates. Full article
(This article belongs to the Special Issue Carbonaceous Aerosols in Atmosphere)
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Open AccessArticle
Contribution from Selected Organic Species to PM2.5 Aerosol during a Summer Field Campaign at K-Puszta, Hungary
Atmosphere 2017, 8(11), 221; https://doi.org/10.3390/atmos8110221
Received: 10 October 2017 / Revised: 8 November 2017 / Accepted: 10 November 2017 / Published: 14 November 2017
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Abstract
A summer field campaign was conducted at the forested background site of K-puszta in Hungary. The main aim was to assess the contribution of terpene-derived particulate organic compounds to the PM2.5 organic carbon (OC) and of the secondary organic carbon (SOC) from [...] Read more.
A summer field campaign was conducted at the forested background site of K-puszta in Hungary. The main aim was to assess the contribution of terpene-derived particulate organic compounds to the PM2.5 organic carbon (OC) and of the secondary organic carbon (SOC) from α-pinene to the OC. The study lasted from 24 May to 29 June 2006; the first half the weather was cold, while the second half was warm. Separate daytime and night-time PM2.5 samples were collected with a high-volume sampler and the samples were analysed by several analytical techniques, including ion chromatography (IC) and liquid chromatography–mass spectrometry (LC/MS). The latter technique was used for measuring the terpene-derived species. Ancillary high time resolution measurements of volatile organic compounds (VOCs) were made with proton-transfer reaction–mass spectrometry. The temporal and diurnal variability of the particulate compounds and VOCs and interrelationships were examined. It was found that the monoterpenes and a number of terpene-derived particulate compounds, such as cis-pinic and cis-caric acid, exhibited a strong day/night difference during the warm period, with about 10 times higher levels during the night-time. During the warm period, the IC compounds and LC/MS compounds accounted, on average, for 3.1% and 2.0%, respectively, of the OC, whereas the contribution of SOC from α-pinene to the OC was estimated at a minimum of 7.1%. Full article
(This article belongs to the Special Issue Carbonaceous Aerosols in Atmosphere)
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Open AccessArticle
The Multi-Wavelength Absorption Analyzer (MWAA) Model as a Tool for Source and Component Apportionment Based on Aerosol Absorption Properties: Application to Samples Collected in Different Environments
Atmosphere 2017, 8(11), 218; https://doi.org/10.3390/atmos8110218
Received: 15 October 2017 / Revised: 6 November 2017 / Accepted: 7 November 2017 / Published: 13 November 2017
Cited by 5 | PDF Full-text (3171 KB) | HTML Full-text | XML Full-text | Supplementary Files
Abstract
The multi-wavelength absorption analyzer model (MWAA model) was recently proposed to provide a source (fossil fuel combustion vs. wood burning) and a component (black carbon BC vs. brown carbon BrC) apportionment of babs measured at different wavelengths, and to provide the BrC [...] Read more.
The multi-wavelength absorption analyzer model (MWAA model) was recently proposed to provide a source (fossil fuel combustion vs. wood burning) and a component (black carbon BC vs. brown carbon BrC) apportionment of babs measured at different wavelengths, and to provide the BrC Ångström Absorption exponent (αBrC). This paper shows MWAA model performances and issues when applied to samples impacted by different sources. To this aim, the MWAA model was run on samples collected at a rural (Propata) and an urban (Milan) site in Italy during the winter period. Lower uncertainties on αBrC and a better correlation of the BrC absorption coefficient (babsBrC) with levoglucosan (tracer for wood burning) were obtained in Propata (compared to Milan). Nevertheless, the correlation previously mentioned improved, especially in Milan, when providing a priori information on αBrC to MWAA. Possible reasons for this improvement could be the more complex mixture of sources present in Milan and the aging processes, which can affect aerosol composition, particle mixing, and size distribution. OC and EC source apportionment showed that wood burning was the dominating contributor to the carbonaceous fractions in Propata, whereas a more complex situation was detected in Milan. Simultaneous babs(BC) apportionment and EC measurements allowed MAC determination, which gave analogous results at the two sites. Full article
(This article belongs to the Special Issue Carbonaceous Aerosols in Atmosphere)
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Open AccessArticle
Evolution of Multispectral Aerosol Absorption Properties in a Biogenically-Influenced Urban Environment during the CARES Campaign
Atmosphere 2017, 8(11), 217; https://doi.org/10.3390/atmos8110217
Received: 16 October 2017 / Revised: 6 November 2017 / Accepted: 8 November 2017 / Published: 13 November 2017
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Abstract
We present the evolution of multispectral optical properties through urban aerosols that have aged and interacted with biogenic emissions, resulting in stronger short wavelength absorption and the formation of moderately brown secondary organic aerosols. Ground-based aerosol measurements were made in June 2010 within [...] Read more.
We present the evolution of multispectral optical properties through urban aerosols that have aged and interacted with biogenic emissions, resulting in stronger short wavelength absorption and the formation of moderately brown secondary organic aerosols. Ground-based aerosol measurements were made in June 2010 within the Sacramento urban area (site T0) and at a 40-km downwind location (site T1) in the forested Sierra Nevada foothills area. Data on black carbon (BC) and non-refractory aerosol mass and composition were collected at both sites. In addition, photoacoustic (PA) instruments with integrating nephelometers were used to measure spectral absorption and scattering coefficients for wavelengths ranging from 355 to 870 nm. The daytime absorption Ångström exponent (AAE) indicated a modest wavelength-dependent enhancement of absorption at both sites throughout the study. From 22 to 28 June 2010, secondary organic aerosol mass increased significantly at both sites, which was due to increased biogenic emissions coupled with intense photochemical activity and air mass recirculation in the area. During this period, the median BC mass-normalized absorption cross-section (MAC) values for 405 nm and 532 nm at T1 increased by ~23% and ~35%, respectively, compared with the relatively less aged urban emissions at the T0 site. In contrast, the average MAC values for the 870 nm wavelength were similar for both sites. These results suggest the formation of moderately brown secondary organic aerosols in biogenically-influenced urban air. Full article
(This article belongs to the Special Issue Carbonaceous Aerosols in Atmosphere)
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Open AccessArticle
On the Redox Activity of Urban Aerosol Particles: Implications for Size Distribution and Relationships with Organic Aerosol Components
Atmosphere 2017, 8(10), 205; https://doi.org/10.3390/atmos8100205
Received: 14 September 2017 / Revised: 16 October 2017 / Accepted: 18 October 2017 / Published: 20 October 2017
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Abstract
This article presents the distribution of the dithiothreitol-based (DTT) redox activity of water-soluble airborne particulate matter (PM) from two urban sites in the city of Thessaloniki, northern Greece in four size ranges (<0.49, 0.49–0.97, 0.97–3.0 and >3 μm). Seasonal and spatial variations are [...] Read more.
This article presents the distribution of the dithiothreitol-based (DTT) redox activity of water-soluble airborne particulate matter (PM) from two urban sites in the city of Thessaloniki, northern Greece in four size ranges (<0.49, 0.49–0.97, 0.97–3.0 and >3 μm). Seasonal and spatial variations are examined. The correlations of the mass-normalized DTT activity with the content of PM in water-soluble organic carbon (WSOC) and non-water-soluble carbonaceous species, such as organic and elemental carbon, as well as with solvent-extractable trace organic compounds (polycyclic aromatic hydrocarbons and nitro-derivatives, polychlorinated biphenyls, organochlorines, polybrominated biphenyl ethers) and polar organic markers (dicarboxylic acids and levoglucosan), are investigated. Our study provides new and additional insights into the ambient size distribution of the DTT activity of the water-soluble fraction of airborne PM at urban sites and its associations with organic PM components. Full article
(This article belongs to the Special Issue Carbonaceous Aerosols in Atmosphere)
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Open AccessArticle
Characterization and Seasonal Variations of Organic and Elemental Carbon and Levoglucosan in PM10 in Krynica Zdroj, Poland
Atmosphere 2017, 8(10), 190; https://doi.org/10.3390/atmos8100190
Received: 17 July 2017 / Revised: 21 September 2017 / Accepted: 22 September 2017 / Published: 25 September 2017
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Abstract
In this study, the ambient aerosol (PM10) concentrations of elemental carbon (EC), organic carbon (OC), total carbon (TC), and levoglucosan are reported for a Polish health resort following a one-year (March 2016–April 2017) sampling campaign. The seasonal variation of OC, EC, [...] Read more.
In this study, the ambient aerosol (PM10) concentrations of elemental carbon (EC), organic carbon (OC), total carbon (TC), and levoglucosan are reported for a Polish health resort following a one-year (March 2016–April 2017) sampling campaign. The seasonal variation of OC, EC, and levoglucosan (LG) concentrations showed their maximum during the heating season for this site, with monthly mean total carbonaceous material/PM10 ratios ranging between about 0.28 and 0.44 depending on the season. Average EC concentration was 1.1 ± 0.6 µg∙m−3 and changed from 0.3 µg∙m−3 up to 2.3 µg∙m−3 during the sampling campaign. The OC concentration at the site ranged from 2.4 µg∙m−3 during the non-heating season up to 22 µg∙m−3 in the heating season, with an average of 7 µg∙m−3. A strong correlation between OC and EC in the heating season suggested that they were produced from similar sources during this time. Mean LG concentration during the sampling campaign was 0.51 µg∙m−3, while in the heating season it was 0.72 µg∙m−3 and in 0.19 µg∙m−3 in the non-heating season. The obtained results indicated a strong influence of local primary source emissions on air quality, especially during the heating period. Full article
(This article belongs to the Special Issue Carbonaceous Aerosols in Atmosphere)
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Open AccessArticle
Summertime Day-Night Differences of PM2.5 Components (Inorganic Ions, OC, EC, WSOC, WSON, HULIS, and PAHs) in Changzhou, China
Atmosphere 2017, 8(10), 189; https://doi.org/10.3390/atmos8100189
Received: 2 August 2017 / Revised: 20 September 2017 / Accepted: 22 September 2017 / Published: 25 September 2017
Cited by 11 | PDF Full-text (1919 KB) | HTML Full-text | XML Full-text
Abstract
This work reports the day-night differences of a suite of chemical species including elemental carbon (EC), organic carbon (OC), water-soluble organic carbon (WSOC), water-soluble organic nitrogen (WSON), selected polycyclic aromatic hydrocarbons (PAHs), and secondary inorganic ions (NO3, SO42− [...] Read more.
This work reports the day-night differences of a suite of chemical species including elemental carbon (EC), organic carbon (OC), water-soluble organic carbon (WSOC), water-soluble organic nitrogen (WSON), selected polycyclic aromatic hydrocarbons (PAHs), and secondary inorganic ions (NO3, SO42−, NH4+) in ambient fine particles (PM2.5) collected from 23 July to 23 August 2016 in Changzhou, China. Mass concentrations of PM2.5 and SO42− show a 10–20% increase during daytime, while NO3 concentration decreases by a factor of three from nighttime to daytime due to its semi-volatile nature. PAHs, EC, and WSON show higher mass concentration in the night too. Mass ratios of WSOC to OC are high in both day and night, indicating that secondary organic aerosol (SOA) formation could occur throughout the day, while the slightly higher ratio during daytime suggests a more significant contribution from daytime photochemical oxidation. Strong positive correlations between HULIS-C and WSOC, and HULIS-C with O3 both in day and night, imply that HULIS-C, similar to WSOC, is mainly composed of secondary species. HULIS-C accounted for a large fraction of WSOC, with an average of ~60%. Moreover, the average WSON concentrations are 1.08 and 1.46 µg/m3, constituting ~16% and ~18% of water-soluble total nitrogen in day and night, respectively. Correlation analyses suggest that WSON is also predominantly produced from secondary processes. PAHs concentrations are found to be very low in summer aerosols. Overall, our findings highlight the dominant contribution of secondary processes to the major aerosol components in Changzhou, suggesting proper measures to effectively reduce gaseous precursors are also important to improve air quality. Full article
(This article belongs to the Special Issue Carbonaceous Aerosols in Atmosphere)
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Open AccessArticle
Estimation of Optical Properties for HULIS Aerosols at Anmyeon Island, Korea
Atmosphere 2017, 8(7), 120; https://doi.org/10.3390/atmos8070120
Received: 8 May 2017 / Revised: 29 June 2017 / Accepted: 4 July 2017 / Published: 7 July 2017
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Abstract
In this study, the sensitivity of the optical properties of carbonaceous aerosols, especially humic-like substances (HULIS), are investigated based on a one-year measurement of ambient fine atmospheric particulate matter (PM2.5) at a Global Atmospheric Watch (GAW) station in South Korea. The [...] Read more.
In this study, the sensitivity of the optical properties of carbonaceous aerosols, especially humic-like substances (HULIS), are investigated based on a one-year measurement of ambient fine atmospheric particulate matter (PM2.5) at a Global Atmospheric Watch (GAW) station in South Korea. The extinction, absorption coefficient, and radiative forcing (RF) are calculated from the analysis data of water soluble (WSOC) and insoluble (WISOC) organic aerosols, elemental carbon (EC), and HULIS. The sensitivity of the optical properties on the variations of refractive index, hygroscopicity, and light absorption properties of HULIS as well as the polydispersity of organic aerosols are studied. The results showed that the seasonal absorption coefficient of HULIS varied from 0.09 to 11.64 Mm−1 and EC varied from 0.11 to 3.04 Mm−1 if the geometric mean diameter varied from 0.1 to 1.0 µm and the geometric standard deviation varied from 1.1 to 2.0, with the imaginary refractive index (IRI) of HULIS varying from 0.006 to 0.3. Subsequently, this study shows that the RF of HULIS was larger than other constituents, which suggested that HULIS contributed significantly to radiative forcing. Full article
(This article belongs to the Special Issue Carbonaceous Aerosols in Atmosphere)
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Open AccessArticle
Characteristics of Carbonaceous Aerosol in a Typical Industrial City—Nanjing in Yangtze River Delta, China: Size Distributions, Seasonal Variations, and Sources
Atmosphere 2017, 8(4), 73; https://doi.org/10.3390/atmos8040073
Received: 27 February 2017 / Revised: 28 March 2017 / Accepted: 5 April 2017 / Published: 7 April 2017
Cited by 7 | PDF Full-text (2375 KB) | HTML Full-text | XML Full-text
Abstract
In order to investigate the size distributions and seasonal variations of carbonaceous aerosols (organic carbon (OC) and elemental carbon (EC)), the carbonaceous species were collected in Nanjing, a typical industrial city located in Yangtze River Delta, China, in the summer, autumn, and winter [...] Read more.
In order to investigate the size distributions and seasonal variations of carbonaceous aerosols (organic carbon (OC) and elemental carbon (EC)), the carbonaceous species were collected in Nanjing, a typical industrial city located in Yangtze River Delta, China, in the summer, autumn, and winter of 2013 and spring of 2014, and then analyzed by using a 9-stage Anderson-type aerosol sampler and DRI Model 2001A Thermal/Optical Carbon Analyzer. OC, EC, secondary organic carbon (SOC), and primary organic carbon (POC) exhibited obvious seasonal variations, with the highest levels in winter (39.1±14.0, 5.7 ± 2.1, 23.6 ± 11.7, and 14.1 ± 5.7 μg·m−3, respectively) and the lowest levels in summer (20.6 ± 6.7, 3.3 ± 2.0, 12.2 ± 3.8 and 8.4 ± 4.1 μg·m−3, respectively), and were mainly centralized in PM1.1 in four seasons. The concentrations of OC in PM1.1 varied in the order of winter > autumn > spring > summer, while EC ranked in the order of autumn > winter > summer > spring. In the PM1.1–2.1 and PM2.1–10, the concentrations of OC and EC decreased in the sequence of winter > spring > autumn > summer. The size spectra of OC, EC, and SOC had bimodal distributions in four seasons, except for EC with four peaks in summer. The size spectra of POC varied greatly with seasons, exhibiting bimodal distribution in winter, trimodal distribution in spring and summer, and four peaks in autumn. The OC/EC ratios were 7.0, 6.3, 7.6, and 6.9 in spring, summer, autumn and winter, respectively, which demonstrated the abundance of secondary organic aerosols in Nanjing. The sources of carbonaceous aerosol varied significantly with seasons, and were dominated by vehicle exhaust, and coal and biomass burning in PM2.1, and dominated by dust, and coal and biomass burning in PM2.1–10. Full article
(This article belongs to the Special Issue Carbonaceous Aerosols in Atmosphere)
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