1. Atmospheric black carbon in the metropolitan area of La Paz and El Alto, Bolivia: concentration levels and emission sourcesValeria Mardoñez-Balderrama, Griša Močnik, Marco Pandolfi, Robin L. Modini, Fernando Velarde, Laura Renzi, Angela Marinoni, Jean-Luc Jaffrezo, Isabel Moreno R., Diego Aliaga, 2024, original scientific article Abstract: Abstract. Black carbon (BC) is a major component of submicron particulate matter (PM), with significant health and climate impacts. Many cities in emerging countries lack comprehensive knowledge about BC emissions and exposure levels. This study investigates BC concentration levels, identifies its emission sources, and characterizes the optical properties of BC at urban background sites of the two largest high-altitude Bolivian cities: La Paz (LP) (3600 m above sea level) and El Alto (EA) (4050 m a.s.l.), where atmospheric oxygen levels and intense radiation may affect BC production. The study relies on concurrent measurements of equivalent black carbon (eBC), elemental carbon (EC), and refractory black carbon (rBC) and their comparison with analogous data collected at the nearby Chacaltaya Global Atmosphere Watch Station (5240 m a.s.l). The performance of two independent source apportionment techniques was compared: a bilinear model and a least-squares multilinear regression (MLR). Maximum eBC concentrations were observed during the local dry season (LP: eBC = 1.5 ± 1.6 µg m−3; EA: 1.9±2.0 µg m−3). While eBC concentrations are lower at the mountain station, daily transport from urban areas is evident. Average mass absorption cross sections of 6.6–8.2 m2 g−1 were found in the urban area at 637 nm. Both source apportionment methods exhibited a reasonable level of agreement in the contribution of biomass burning (BB) to absorption. The MLR method allowed the estimation of the contribution and the source-specific optical properties for multiple sources, including open waste burning. Keywords: black carbon, aerosol absorption, source apportionment, mass absorption cross-section Published in RUNG: 29.10.2024; Views: 579; Downloads: 0
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2. Oxidative potential of particulate matter and its association to respiratory health endpoints in high-altitude cities in BoliviaLucille Borlaza-Lacoste, Valeria Mardoñez, Anouk Marsal, Ian Hough, Thuy Vy Dinh Ngoc, Pamela Dominutti, Jean-Luc Jaffrezo, Andrés Alastuey, Jean-Luc Besombes, Griša Močnik, 2024, original scientific article Keywords: particulate matter, oxidative potential, respiratory health, Bolivia, source apportionment, Positive matrix factorization, Poisson regression Published in RUNG: 22.05.2024; Views: 1271; Downloads: 1
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3. Emission of volatile organic compounds from residential biomass burning and their rapid chemical transformationsMaximillien Desservettaz, Michael Pikridas, Iasonas Stavroulas, Aikaterini Bougiatioti, Eleni Liakakou, Nikolaos Hatzianastassiou, Jean Sciare, Nikolaos Mihalopoulos, Efstratios Bourtsoukidis, 2023, original scientific article Abstract: Biomass combustion releases a complex array of Volatile Organic Compounds (VOCs) that pose significant challenges to air quality and human health. Although biomass burning has been extensively studied at ecosystem levels, understanding the atmospheric transformation and impact on air quality of emissions in urban environments remains challenging due to complex sources and burning materials. In this study, we investigate the VOC emission rates and atmospheric chemical processing of predominantly wood burning emissions in a small urban centre in Greece. Ioannina is situated in a valley within the Dinaric Alps and experiences intense atmospheric pollution accumulation during winter due to its topography and high wood burning activity. During pollution event days, the ambient mixing ratios of key VOC species were found to be similar to those reported for major urban centres worldwide. Positive matrix factorisation (PMF) analysis revealed that biomass burning was the dominant emission source (>50 %), representing two thirds of OH reactivity, which indicates a highly reactive atmospheric mixture. Calculated OH reactivity ranges from 5 s−1 to an unprecedented 278 s−1, and averages at 93 ± 66 s−1 at 9 PM, indicating the presence of exceptionally reactive VOCs. The highly pronounced photochemical formation of organic acids coincided with the formation of ozone, highlighting the significance of secondary formation of pollutants in poorly ventilated urban areas. Our findings underscore the pressing need to transition from wood burning to environmentally friendly sources of energy in poorly ventilated urban areas, in order to improve air quality and safeguard public health. Keywords: biomass burning, urban air quality, VOCs, emission factors, source apportionment Published in RUNG: 13.05.2024; Views: 1188; Downloads: 5
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4. Sources and processes that control the submicron organic aerosol composition in an urban Mediterranean environment (Athens) : a high temporal-resolution chemical composition measurement studyIasonas Stavroulas, Aikaterini Bougiatioti, Georgios Grivas, D. Paraskevopoulou, M. Tsagkaraki, Pavlos Zarmpas, Eleni Liakakou, Evangelos Gerasopoulos, Nikolaos Mihalopoulos, 2019, original scientific article Abstract: Submicron aerosol chemical composition was studied during a year-long
period (26 July 2016–31 July 2017) and two wintertime intensive campaigns
(18 December 2013–21 February 2014 and 23 December 2015–17 February 2016),
at a central site in Athens, Greece, using an Aerosol Chemical Speciation
Monitor (ACSM). Concurrent measurements included a particle-into-liquid
sampler (PILS-IC), a scanning mobility particle sizer (SMPS), an AE-33
Aethalometer, and ion chromatography analysis on 24 or 12 h filter samples.
The aim of the study was to characterize the seasonal variability of the main
submicron aerosol constituents and decipher the sources of organic aerosol
(OA). Organics were found to contribute almost half of the submicron mass,
with 30 min resolution concentrations during wintertime reaching up to
200 µg m−3. During winter (all three campaigns combined),
primary sources contributed about 33 % of the organic fraction, and comprised
biomass burning (10 %), fossil fuel combustion (13 %), and cooking
(10 %), while the remaining 67 % was attributed to secondary aerosol.
The semi-volatile component of the oxidized organic aerosol (SV-OOA;
22 %) was found to be clearly linked to combustion sources, in
particular biomass burning; part of the very oxidized,
low-volatility component (LV-OOA; 44 %) could also be attributed to the
oxidation of emissions from these primary combustion sources. These results, based on the combined contribution of biomass burning organic
aerosol (BBOA) and SV-OOA, indicate the importance of increased biomass
burning in the urban environment of Athens as a result of the economic recession.
During summer, when concentrations of fine aerosols are considerably lower,
more than 80 % of the organic fraction is attributed to secondary aerosol
(SV-OOA 31 % and LV-OOA 53 %). In contrast to winter, SV-OOA appears
to result from a well-mixed type of aerosol that is linked to fast photochemical
processes and the oxidation of primary traffic and biogenic emissions.
Finally, LV-OOA presents a more regional character in summer, owing to the
oxidation of OA over the period of a few days. Keywords: ACSM, organic aerosol, PMF, source apportionment Published in RUNG: 13.05.2024; Views: 1322; Downloads: 5
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5. Measurement of atmospheric black carbon in some South Mediterranean cities : seasonal variations and source apportionmentHamza Merabet, Rabah Kerbachi, Nikolaos Mihalopoulos, Iasonas Stavroulas, Maria Kanakidou, Noureddine Yassaa, 2019, original scientific article Abstract: This study aims to investigate, for the first time in Algeria, the atmospheric black carbon (BC) concentrations over one year measured at the Scientific Observatory of Algiers and to compare their concentration levels with other Mediterranean cities (i.e., Athens and Crete). The diurnal cycles as well as seasonal variations of BC concentrations were evaluated and attributed to their emission sources (fossil fuel: BCff and wood burning: BCwb). The annual mean concentrations of BC, BCff and BCwb were 1.113±2.030, 1.064±2.002 and 0.049±0.262 µgm-3, respectively. The highest seasonal mean concentrations were recorded in summer and autumn with 1.283±1.346 and 1.209±1.149 µgm-3 for BC and 1.217±1.431 and 1.177±1.151 µgm-3 for BCff, respectively. However, the lowest mean concentrations were recorded in winter and spring with 1.023±1.189 and 0.966±0.964 µgm-3 for BC and 0.933±1.177 and 0.956±0.874 µgm-3 for BCff, respectively. For BCwb, the highest mean concentrations were reached in winter and summer with 0.090±0.055 and 0.066±0.050 µgm-3, respectively, very likely due to the forest fires and long-range transport of air pollution from Europe. The lowest mean concentrations of BCwb were recorded in autumn and spring with 0.032±0.033 and 0.010±0.021 µgm-3, respectively. Seggregating BC levels into eight wind sectors, showed that the prevailing BC pollution with concentrations reaching up to 5.000 µgm-3 originated from the North-West wind sector. A source apportionment of BC for the wet and dry period was also perfomed followed by a back trajectory cluster analysis for long-range transport. Keywords: aerosol, black carbon, atmospheric pollution, source apportionment, seasonal variation, year modulation Published in RUNG: 10.05.2024; Views: 1021; Downloads: 7
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6. Long-term variability, source apportionment and spectral properties of black carbon at an urban background site in Athens, GreeceEleni Liakakou, Iasonas Stavroulas, Dimitris G. Kaskaoutis, Georgios Grivas, D. Paraskevopoulou, Umesh Chandra Dumka, M. Tsagkaraki, Aikaterini Bougiatioti, K. Oikonomou, J. Sciare, 2020, original scientific article Abstract: This study aims to delineate the characteristics of Black Carbon (BC) in the atmosphere over Athens, Greece, using 4-year (May 2015–April 2019) Aethalometer (AE-33) measurements. The average BC concentration is 1.9 ± 2.5 μg m−3 (ranging from 0.1 to 32.7 μg m−3; hourly values), with a well-defined seasonality from 1.3 ± 1.1 μg m−3 in summer to 3.0 ± 4.0 μg m−3 in winter. Pronounced morning and evening/night peaks are found in the BC concentrations in winter, while during the rest of the seasons, this diurnal cycle appears to flatten out, with the exception of the morning traffic peak. On an annual basis, the biomass-burning fraction (BB%) of BC accounts for 22 ± 12%, while the fossil-fuel combustion (BCff) component (traffic emissions and domestic heating) dominates during summer (83%) and in the morning hours. BCwb exhibits higher contribution in winter (32%), especially during the night hours (39%). BC levels are effectively reduced by precipitation, while they significantly build-up for wind speeds <3 m s−1 and mixing-layer height (MLH) < 500 m. Normalizing the BC diurnal course by the MLH variations on a seasonal basis reveals that the residential wood-burning emissions are mostly responsible for the large BC increase during winter nights, whereas the low BC levels during daytime in the warm season are mainly attributed to dilution into a deeper MLH. BCwb is highly correlated with other BB tracers during winter nights (e.g. levoglucosan, non-sea-salt-K+, m/z 60 fragment), as well as with the fine fraction (PM2.5) OC and EC. The Delta-C, which represents the spectral dependence of BC as the absorption difference between 370 and 880 nm, is analyzed for the first time in Athens. It exhibits a pronounced seasonality with maximum values in winter night-time, and it appears as a valid qualitative marker for wood combustion. Keywords: black carbon, wood burning, source apportionment, mixing layer, biomass burning tracers, Athens Published in RUNG: 10.05.2024; Views: 1161; Downloads: 2
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7. Compositional changes of ▫$PM_2.5$▫ in NE Spain during 2009–2018 : a trend analysis of the chemical composition and source apportionmentMarten in 't Veld, Andrés Alastuey, Marco Pandolfi, Fulvio Amato, Noemí Perez, Cristina Reche, Marta Via, Maria Cruz Minguillon, Miguel Escudero, Xavier Querol, 2021, original scientific article Keywords: PM2.5, aerosol, source apportionment Published in RUNG: 10.05.2024; Views: 1196; Downloads: 3
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8. Apportionment of black and brown carbon spectral absorption sources in the urban environment of Athens, Greece, during winterDimitris G. Kaskaoutis, Georgios Grivas, Iasonas Stavroulas, Aikaterini Bougiatioti, Eleni Liakakou, Umesh Chandra Dumka, Evangelos Gerasopoulos, Nikolaos Mihalopoulos, 2021, original scientific article Abstract: This study examines the spectral properties and source characteristics of absorbing aerosols (BC: Black Carbon; BrC: Brown Carbon, based on aethalometer measurements) in the urban background of Athens during December 2016–February 2017. Using common assumptions regarding the spectral dependence of absorption due to BC (AAEBC = 1) and biomass burning (AAEbb = 2), and calculating an optimal AAEff value for the dataset (1.18), the total spectral absorption was decomposed into five components, corresponding to absorption of BC and BrC from fossil-fuel (ff) combustion and biomass burning (bb), and to secondary BrC estimated using the BC-tracer minimum R-squared (MRS) method. Substantial differences in the contribution of various components to the total absorption were found between day and night, due to differences in emissions and meteorological dynamics, while BrC and biomass burning aerosols presented higher contributions at shorter wavelengths. At 370 nm, the absorption due to BCff contributed 36.3% on average, exhibiting a higher fraction (58.1%) during daytime, while the mean BCbb absorption was estimated at 18.4%. The mean absorption contributions due to BrCff, BrCbb and BrCsec were 6.7%, 32.3% and 4.9%, respectively. The AbsBCff,370 component maximized during the morning traffic hours and was strongly correlated with NOx (R2 = 0.76) and CO (R2 = 0.77), while a similar behavior was seen for the AbsBrCff,370 component. AbsBCbb and AbsBrCbb levels escalated during nighttime and were highly associated with nss-K+ and with the organic aerosol (OA) components related to fresh and fast-oxidized biomass burning (BBOA and SV-OOA) as obtained from ACSM measurements. Multiple linear regression was used to attribute BrC absorption to five OA components and to determine their absorption contributions and efficiencies, revealing maximum contributions of BBOA (33%) and SV-OOA (21%). Sensitivity analysis was performed in view of the methodological uncertainties and supported the reliability of the results, which can have important implications for radiative transfer models. Keywords: spectral absorption, black carbon, brown carbon, fossil fuel, biomass burning, source apportionment Published in RUNG: 10.05.2024; Views: 1161; Downloads: 0 This document has many files! More... |
9. Ambient carbonaceous aerosol levels in Cyprus and the role of pollution transport from the Middle EastAliki Christodoulou, Iasonas Stavroulas, Mihalis Vrekoussis, Maximillien Desservettaz, Michael Pikridas, Elie Bimenyimana, Jonilda Kushta, Matic Ivančič, Martin Rigler, Philippe Goloub, 2023, original scientific article Abstract: Abstract. The geographical origin and source apportionment of submicron carbonaceous aerosols (organic aerosols, OAs, and black carbon, BC) have been investigated here for the first time, deploying high time-resolution measurements at an urban background site of Nicosia, the capital
city of Cyprus, in the eastern Mediterranean. This study covers a half-year
period, encompassing both the cold and warm periods with continuous
observations of the physical and chemical properties of PM1 performed
with an Aerosol Chemical Speciation Monitor (ACSM), an aethalometer,
accompanied by a suite of various ancillary offline and online measurements. Carbonaceous aerosols were dominant during both seasons (cold and warm periods), with a contribution of 57 % and 48 % to PM1, respectively, and exhibited recurrent intense nighttime peaks (> 20–30 µg m−3) during the cold period, associated with local domestic heating. The findings of this study show that high concentrations of sulfate (close to 3 µg m−3) were continuously recorded, standing among the highest ever reported for Europe and originating from the Middle East region. Source apportionment of the OA and BC fractions was performed using the
positive matrix factorization (PMF) approach and the combination of two
models (aethalometer model and multilinear regression), respectively. Our
study revealed elevated hydrocarbon-like organic aerosol (HOA)
concentrations in Nicosia (among the highest reported for a European urban
background site), originating from a mixture of local and regional
fossil fuel combustion sources. Although air masses from the Middle East had
a low occurrence and were observed mostly during the cold period, they were
shown to strongly affect the mean concentrations levels of BC and OA in
Nicosia during both seasons. Overall, the present study brings to our
attention the need to further characterize primary and secondary
carbonaceous aerosols in the Middle East, an undersampled region
characterized by continuously increasing fossil fuel (oil and gas) emissions
and extreme environmental conditions, which can contribute to photochemical
ageing. Keywords: PM1, BC, source apportionment, Cyprus, long range transport Published in RUNG: 10.05.2024; Views: 1062; Downloads: 6
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10. Rolling vs. seasonal PMF : real-world multi-site and synthetic dataset comparisonMarta Via, Gang Chen, Francesco Canonaco, Kaspar Rudolf Daellenbach, Benjamin Chazeau, Hasna Chebaicheb, Jianhui Jiang, Hannes Keernik, Chunshui Lin, Nicolas Marchand, 2022, original scientific article Abstract: Abstract. Particulate matter (PM) has become a major concern in terms of human health
and climate impact. In particular, the source apportionment (SA) of organic
aerosols (OA) present in submicron particles (PM1) has gained relevance
as an atmospheric research field due to the diversity and complexity of its
primary sources and secondary formation processes. Moreover, relatively
simple but robust instruments such as the Aerosol Chemical Speciation
Monitor (ACSM) are now widely available for the near-real-time online
determination of the composition of the non-refractory PM1. One of the
most used tools for SA purposes is the source-receptor positive matrix
factorisation (PMF) model. Even though the recently developed rolling PMF technique has
already been used for OA SA on ACSM datasets, no study has assessed its
added value compared to the more common seasonal PMF method using a practical
approach yet. In this paper, both techniques were applied to a synthetic
dataset and to nine European ACSM datasets in order to spot the main output
discrepancies between methods. The main advantage of the synthetic dataset
approach was that the methods' outputs could be compared to the expected
“true” values, i.e. the original synthetic dataset values. This approach
revealed similar apportionment results amongst methods, although the
rolling PMF profile's adaptability feature proved to be advantageous, as it
generated output profiles that moved nearer to the truth points. Nevertheless,
these results highlighted the impact of the profile anchor on the solution,
as the use of a different anchor with respect to the truth led to
significantly different results in both methods. In the multi-site study,
while differences were generally not significant when considering year-long
periods, their importance grew towards shorter time spans, as in intra-month
or intra-day cycles. As far as correlation with external measurements is
concerned, rolling PMF performed better than seasonal PMF globally for the ambient
datasets investigated here, especially in periods between seasons. The results of this
multi-site comparison coincide with the synthetic dataset in terms of
rolling–seasonal similarity and rolling PMF reporting moderate improvements. Altogether, the
results of this study provide solid evidence of the robustness of both
methods and of the overall efficiency of the recently proposed rolling PMF
approach. Keywords: particulate matter, synthetic dataset comparison, source apportionment, organic aerosols Published in RUNG: 10.05.2024; Views: 1224; Downloads: 7
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