Absorption enhancement of black carbon particles in a Mediterranean city and countryside: effect of particulate matter chemistry, ageing and trend analysis
<p>Black carbon (BC) is recognized as the most important warming agent among atmospheric aerosol particles. The absorption efficiency of pure BC is rather well-known, nevertheless the mixing of BC with other aerosol particles can enhance the BC light absorption efficiency, thus directly affect...
| Main Authors: | , , , , , , , , , , |
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| Format: | Article |
| Language: | English |
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Copernicus Publications
2022-07-01
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| Series: | Atmospheric Chemistry and Physics |
| Online Access: | https://acp.copernicus.org/articles/22/8439/2022/acp-22-8439-2022.pdf |
| _version_ | 1811318840688115712 |
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| author | J. Yus-Díez J. Yus-Díez M. Via M. Via A. Alastuey A. Karanasiou M. C. Minguillón N. Perez X. Querol C. Reche M. Ivančič M. Rigler M. Pandolfi |
| author_facet | J. Yus-Díez J. Yus-Díez M. Via M. Via A. Alastuey A. Karanasiou M. C. Minguillón N. Perez X. Querol C. Reche M. Ivančič M. Rigler M. Pandolfi |
| author_sort | J. Yus-Díez |
| collection | DOAJ |
| description | <p>Black carbon (BC) is recognized as the most important warming agent among atmospheric aerosol particles. The absorption efficiency of pure BC is rather well-known, nevertheless the mixing of BC with other aerosol particles can enhance the BC light absorption efficiency, thus directly affecting Earth's radiative balance. The effects on climate of the BC absorption enhancement due to the mixing with these aerosols are not yet well constrained because these effects depend on the availability of material for mixing with BC, thus creating regional variations.</p>
<p>Here we present the mass absorption cross-section (MAC) and absorption enhancement of BC particles (<span class="inline-formula"><i>E</i><sub>abs</sub></span>), at different wavelengths (from 370 to 880 nm for online measurements and at 637 nm for offline measurements) measured at two sites in the western Mediterranean, namely Barcelona (BCN; urban background) and Montseny (MSY; regional background). The <span class="inline-formula"><i>E</i><sub>abs</sub></span> values ranged between 1.24 and 1.51 at the urban station, depending on the season and wavelength used as well as on the pure BC MAC used as a reference. The largest contribution to <span class="inline-formula"><i>E</i><sub>abs</sub></span> was due to the internal mixing of BC particles with other aerosol compounds, on average between a 91 % and a 100 % at 370 and 880 nm, respectively. Additionally, 14.5 % and 4.6 % of the total enhancement at the short ultraviolet (UV) wavelength (370 nm) was due to externally mixed brown carbon (BrC) particles during the cold and the warm period, respectively. On average, at the MSY station, a higher <span class="inline-formula"><i>E</i><sub>abs</sub></span> value was observed (1.83 at 637 nm) compared to BCN (1.37 at 637 nm), which was associated with the higher fraction of organic aerosols (OA) available for BC coating at the regional station, as denoted by the higher organic carbon to elemental carbon (<span class="inline-formula">OC:EC</span>) ratio observed at MSY compared to BCN. At both BCN and MSY, <span class="inline-formula"><i>E</i><sub>abs</sub></span> showed an exponential increase with the amount of non-refractory (NR) material available for coating (<span class="inline-formula"><i>R</i><sub>NR-PM</sub></span>). The <span class="inline-formula"><i>E</i><sub>abs</sub></span> at 637 nm at the MSY regional station reached values up to 3 during episodes with high <span class="inline-formula"><i>R</i><sub>NR-PM</sub></span>, whereas in BCN, <span class="inline-formula"><i>E</i><sub>abs</sub></span> kept values lower than 2 due to the lower relative amount of coating materials measured at BCN compared to MSY. The main sources of OA influencing <span class="inline-formula"><i>E</i><sub>abs</sub></span> throughout the year were hydrocarbon OA (HOA) and cooking-related OA (COA), i.e. primary OA (POA) from traffic and cooking emissions, respectively, at both 370 and 880 nm. At the short UV wavelength (370 nm), a strong contribution to <span class="inline-formula"><i>E</i><sub>abs</sub></span> from biomass burning OA (BBOA) and less oxidized oxygenated OA (LO-OOA) sources was observed in the colder period. Moreover, we found an increase of <span class="inline-formula"><i>E</i><sub>abs</sub></span> with the ageing state of the particles, especially during the colder period. This increase of <span class="inline-formula"><i>E</i><sub>abs</sub></span> with particle ageing was associated with a larger relative amount of secondary OA (SOA) compared to POA. The availability of a long dataset at both stations from offline measurements enabled a decade-long trend analysis of <span class="inline-formula"><i>E</i><sub>abs</sub></span> at 637 nm, that showed statistically significant (s.s.) positive trends of <span class="inline-formula"><i>E</i><sub>abs</sub></span> during the warmer months at the MSY station. This s.s. positive trend in MSY mirrored the observed increase of the <span class="inline-formula">OC:EC</span> ratio over time. Moreover, in BCN during the COVID-19 lockdown period in spring 2020 we observed a sharp increase of <span class="inline-formula"><i>E</i><sub>abs</sub></span> due to the observed sharp increase of the <span class="inline-formula">OC:EC</span> ratio. Our results show similar values of <span class="inline-formula"><i>E</i><sub>abs</sub></span> to those found in the literature for similar background stations.</p> |
| first_indexed | 2024-04-13T12:32:18Z |
| format | Article |
| id | doaj.art-118f21444fff45fb8c53f51c64f78d0b |
| institution | Directory Open Access Journal |
| issn | 1680-7316 1680-7324 |
| language | English |
| last_indexed | 2024-04-13T12:32:18Z |
| publishDate | 2022-07-01 |
| publisher | Copernicus Publications |
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| series | Atmospheric Chemistry and Physics |
| spelling | doaj.art-118f21444fff45fb8c53f51c64f78d0b2022-12-22T02:46:47ZengCopernicus PublicationsAtmospheric Chemistry and Physics1680-73161680-73242022-07-01228439845610.5194/acp-22-8439-2022Absorption enhancement of black carbon particles in a Mediterranean city and countryside: effect of particulate matter chemistry, ageing and trend analysisJ. Yus-Díez0J. Yus-Díez1M. Via2M. Via3A. Alastuey4A. Karanasiou5M. C. Minguillón6N. Perez7X. Querol8C. Reche9M. Ivančič10M. Rigler11M. Pandolfi12Institute of Environmental Assessment and Water Research (IDAEA-CSIC), Barcelona, 08034, SpainGrup de Meteorologia, Departament de Física Aplicada, Universitat de Barcelona, C/Martí i Franquès, 1, 08028, Barcelona, SpainInstitute of Environmental Assessment and Water Research (IDAEA-CSIC), Barcelona, 08034, SpainGrup de Meteorologia, Departament de Física Aplicada, Universitat de Barcelona, C/Martí i Franquès, 1, 08028, Barcelona, SpainInstitute of Environmental Assessment and Water Research (IDAEA-CSIC), Barcelona, 08034, SpainInstitute of Environmental Assessment and Water Research (IDAEA-CSIC), Barcelona, 08034, SpainInstitute of Environmental Assessment and Water Research (IDAEA-CSIC), Barcelona, 08034, SpainInstitute of Environmental Assessment and Water Research (IDAEA-CSIC), Barcelona, 08034, SpainInstitute of Environmental Assessment and Water Research (IDAEA-CSIC), Barcelona, 08034, SpainInstitute of Environmental Assessment and Water Research (IDAEA-CSIC), Barcelona, 08034, SpainAerosol d.o.o., Ljubljana, SloveniaAerosol d.o.o., Ljubljana, SloveniaInstitute of Environmental Assessment and Water Research (IDAEA-CSIC), Barcelona, 08034, Spain<p>Black carbon (BC) is recognized as the most important warming agent among atmospheric aerosol particles. The absorption efficiency of pure BC is rather well-known, nevertheless the mixing of BC with other aerosol particles can enhance the BC light absorption efficiency, thus directly affecting Earth's radiative balance. The effects on climate of the BC absorption enhancement due to the mixing with these aerosols are not yet well constrained because these effects depend on the availability of material for mixing with BC, thus creating regional variations.</p> <p>Here we present the mass absorption cross-section (MAC) and absorption enhancement of BC particles (<span class="inline-formula"><i>E</i><sub>abs</sub></span>), at different wavelengths (from 370 to 880 nm for online measurements and at 637 nm for offline measurements) measured at two sites in the western Mediterranean, namely Barcelona (BCN; urban background) and Montseny (MSY; regional background). The <span class="inline-formula"><i>E</i><sub>abs</sub></span> values ranged between 1.24 and 1.51 at the urban station, depending on the season and wavelength used as well as on the pure BC MAC used as a reference. The largest contribution to <span class="inline-formula"><i>E</i><sub>abs</sub></span> was due to the internal mixing of BC particles with other aerosol compounds, on average between a 91 % and a 100 % at 370 and 880 nm, respectively. Additionally, 14.5 % and 4.6 % of the total enhancement at the short ultraviolet (UV) wavelength (370 nm) was due to externally mixed brown carbon (BrC) particles during the cold and the warm period, respectively. On average, at the MSY station, a higher <span class="inline-formula"><i>E</i><sub>abs</sub></span> value was observed (1.83 at 637 nm) compared to BCN (1.37 at 637 nm), which was associated with the higher fraction of organic aerosols (OA) available for BC coating at the regional station, as denoted by the higher organic carbon to elemental carbon (<span class="inline-formula">OC:EC</span>) ratio observed at MSY compared to BCN. At both BCN and MSY, <span class="inline-formula"><i>E</i><sub>abs</sub></span> showed an exponential increase with the amount of non-refractory (NR) material available for coating (<span class="inline-formula"><i>R</i><sub>NR-PM</sub></span>). The <span class="inline-formula"><i>E</i><sub>abs</sub></span> at 637 nm at the MSY regional station reached values up to 3 during episodes with high <span class="inline-formula"><i>R</i><sub>NR-PM</sub></span>, whereas in BCN, <span class="inline-formula"><i>E</i><sub>abs</sub></span> kept values lower than 2 due to the lower relative amount of coating materials measured at BCN compared to MSY. The main sources of OA influencing <span class="inline-formula"><i>E</i><sub>abs</sub></span> throughout the year were hydrocarbon OA (HOA) and cooking-related OA (COA), i.e. primary OA (POA) from traffic and cooking emissions, respectively, at both 370 and 880 nm. At the short UV wavelength (370 nm), a strong contribution to <span class="inline-formula"><i>E</i><sub>abs</sub></span> from biomass burning OA (BBOA) and less oxidized oxygenated OA (LO-OOA) sources was observed in the colder period. Moreover, we found an increase of <span class="inline-formula"><i>E</i><sub>abs</sub></span> with the ageing state of the particles, especially during the colder period. This increase of <span class="inline-formula"><i>E</i><sub>abs</sub></span> with particle ageing was associated with a larger relative amount of secondary OA (SOA) compared to POA. The availability of a long dataset at both stations from offline measurements enabled a decade-long trend analysis of <span class="inline-formula"><i>E</i><sub>abs</sub></span> at 637 nm, that showed statistically significant (s.s.) positive trends of <span class="inline-formula"><i>E</i><sub>abs</sub></span> during the warmer months at the MSY station. This s.s. positive trend in MSY mirrored the observed increase of the <span class="inline-formula">OC:EC</span> ratio over time. Moreover, in BCN during the COVID-19 lockdown period in spring 2020 we observed a sharp increase of <span class="inline-formula"><i>E</i><sub>abs</sub></span> due to the observed sharp increase of the <span class="inline-formula">OC:EC</span> ratio. Our results show similar values of <span class="inline-formula"><i>E</i><sub>abs</sub></span> to those found in the literature for similar background stations.</p>https://acp.copernicus.org/articles/22/8439/2022/acp-22-8439-2022.pdf |
| spellingShingle | J. Yus-Díez J. Yus-Díez M. Via M. Via A. Alastuey A. Karanasiou M. C. Minguillón N. Perez X. Querol C. Reche M. Ivančič M. Rigler M. Pandolfi Absorption enhancement of black carbon particles in a Mediterranean city and countryside: effect of particulate matter chemistry, ageing and trend analysis Atmospheric Chemistry and Physics |
| title | Absorption enhancement of black carbon particles in a Mediterranean city and countryside: effect of particulate matter chemistry, ageing and trend analysis |
| title_full | Absorption enhancement of black carbon particles in a Mediterranean city and countryside: effect of particulate matter chemistry, ageing and trend analysis |
| title_fullStr | Absorption enhancement of black carbon particles in a Mediterranean city and countryside: effect of particulate matter chemistry, ageing and trend analysis |
| title_full_unstemmed | Absorption enhancement of black carbon particles in a Mediterranean city and countryside: effect of particulate matter chemistry, ageing and trend analysis |
| title_short | Absorption enhancement of black carbon particles in a Mediterranean city and countryside: effect of particulate matter chemistry, ageing and trend analysis |
| title_sort | absorption enhancement of black carbon particles in a mediterranean city and countryside effect of particulate matter chemistry ageing and trend analysis |
| url | https://acp.copernicus.org/articles/22/8439/2022/acp-22-8439-2022.pdf |
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