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Cloud condensation nuclei activation properties of Mediterranean pollen types considering organic chemical composition and surface tension effects
https://orcid.org/0000-0001-7142-5362
https://orcid.org/0000-0003-1855-1313
https://orcid.org/0000-0001-6372-723X
https://orcid.org/0000-0002-8778-3508
https://orcid.org/0000-0002-6434-3390
https://orcid.org/0000-0002-0901-1609
https://orcid.org/0000-0002-9394-024X
https://orcid.org/0000-0002-4453-1263
https://orcid.org/0000-0001-9283-3891
https://orcid.org/0000-0002-7679-6135
https://orcid.org/0000-0002-0186-1721
https://orcid.org/0000-0003-3576-7167
https://orcid.org/0000-0002-8955-2383
https://orcid.org/0000-0003-3630-5079
Abstract Wind-dispersed pollen grains emitted from vegetation are directly injected into the atmosphere being an important source of natural aerosols globally. These coarse particles of pollen can rupture into smaller particles, known as subpollen particles (SPPs), that may act as cloud condensation nuclei (CCN) and affect the climate. In this study, we characterize and investigate the ability of SPPs of 10 Mediterranean-climate pollen types to activate as CCN. A continuous flow CCN counter (CCNC) was used to measure the activation of size-selected (80, 100 and 200 nm dry mobility diameter) particles at different supersaturations (SS). Hygroscopicity parameter (κ) for each SPP type and size has been calculated using κ-Köhler theory. Organic chemical speciation and protein content has been determined to further characterize pollen solutions. Furthermore, the surface activity of SPPs has also been investigated by using pendant drop tensiometry. All studied SPP samples show critical supersaturation (SS Crit) values that are atmospherically relevant SS conditions. Hygroscopicity κ values are in the range characteristic of organic compounds (0.1–0.3). We found that organic speciation and protein content vary substantially among pollen types, with saccharides and fatty acids being the only organic compounds found in all pollen types. A clear relationship between SPP activation and its organic composition was not observed. This study also reveals that all SPPs investigated reduce the surface tension of water at high concentrations but at diluted concentrations (such as those of activation in the CCNC), the water surface tension value is a good approximation in Köhler theory. Overall, this analysis points out that pollen particles might be an important source of CCN in the atmosphere and should be considered in aerosol-cloud interactions processes.
Graphical abstract Display Omitted
Highlights Subpollen particles (SPPs) show κ values in the 0.1–0.3 range. SPPs activate as CCN at atmospheric supersaturation conditions. Saccharides and fatty acids are organic compounds found in all pollen types. The droplet surface tension reduction is observed at high concentration of SPPs. Reduction of surface tension does not show a relevant effect on SPP activation.
Cloud condensation nuclei activation properties of Mediterranean pollen types considering organic chemical composition and surface tension effects
https://orcid.org/0000-0001-7142-5362
https://orcid.org/0000-0003-1855-1313
https://orcid.org/0000-0001-6372-723X
https://orcid.org/0000-0002-8778-3508
https://orcid.org/0000-0002-6434-3390
https://orcid.org/0000-0002-0901-1609
https://orcid.org/0000-0002-9394-024X
https://orcid.org/0000-0002-4453-1263
https://orcid.org/0000-0001-9283-3891
https://orcid.org/0000-0002-7679-6135
https://orcid.org/0000-0002-0186-1721
https://orcid.org/0000-0003-3576-7167
https://orcid.org/0000-0002-8955-2383
https://orcid.org/0000-0003-3630-5079
Abstract Wind-dispersed pollen grains emitted from vegetation are directly injected into the atmosphere being an important source of natural aerosols globally. These coarse particles of pollen can rupture into smaller particles, known as subpollen particles (SPPs), that may act as cloud condensation nuclei (CCN) and affect the climate. In this study, we characterize and investigate the ability of SPPs of 10 Mediterranean-climate pollen types to activate as CCN. A continuous flow CCN counter (CCNC) was used to measure the activation of size-selected (80, 100 and 200 nm dry mobility diameter) particles at different supersaturations (SS). Hygroscopicity parameter (κ) for each SPP type and size has been calculated using κ-Köhler theory. Organic chemical speciation and protein content has been determined to further characterize pollen solutions. Furthermore, the surface activity of SPPs has also been investigated by using pendant drop tensiometry. All studied SPP samples show critical supersaturation (SS Crit) values that are atmospherically relevant SS conditions. Hygroscopicity κ values are in the range characteristic of organic compounds (0.1–0.3). We found that organic speciation and protein content vary substantially among pollen types, with saccharides and fatty acids being the only organic compounds found in all pollen types. A clear relationship between SPP activation and its organic composition was not observed. This study also reveals that all SPPs investigated reduce the surface tension of water at high concentrations but at diluted concentrations (such as those of activation in the CCNC), the water surface tension value is a good approximation in Köhler theory. Overall, this analysis points out that pollen particles might be an important source of CCN in the atmosphere and should be considered in aerosol-cloud interactions processes.
Graphical abstract Display Omitted
Highlights Subpollen particles (SPPs) show κ values in the 0.1–0.3 range. SPPs activate as CCN at atmospheric supersaturation conditions. Saccharides and fatty acids are organic compounds found in all pollen types. The droplet surface tension reduction is observed at high concentration of SPPs. Reduction of surface tension does not show a relevant effect on SPP activation.
Cloud condensation nuclei activation properties of Mediterranean pollen types considering organic chemical composition and surface tension effects
https://orcid.org/0000-0001-7142-5362
https://orcid.org/0000-0003-1855-1313
https://orcid.org/0000-0001-6372-723X
https://orcid.org/0000-0002-8778-3508
https://orcid.org/0000-0002-6434-3390
https://orcid.org/0000-0002-0901-1609
https://orcid.org/0000-0002-9394-024X
https://orcid.org/0000-0002-4453-1263
https://orcid.org/0000-0001-9283-3891
https://orcid.org/0000-0002-7679-6135
https://orcid.org/0000-0002-0186-1721
https://orcid.org/0000-0003-3576-7167
https://orcid.org/0000-0002-8955-2383
https://orcid.org/0000-0003-3630-5079
Abstract Wind-dispersed pollen grains emitted from vegetation are directly injected into the atmosphere being an important source of natural aerosols globally. These coarse particles of pollen can rupture into smaller particles, known as subpollen particles (SPPs), that may act as cloud condensation nuclei (CCN) and affect the climate. In this study, we characterize and investigate the ability of SPPs of 10 Mediterranean-climate pollen types to activate as CCN. A continuous flow CCN counter (CCNC) was used to measure the activation of size-selected (80, 100 and 200 nm dry mobility diameter) particles at different supersaturations (SS). Hygroscopicity parameter (κ) for each SPP type and size has been calculated using κ-Köhler theory. Organic chemical speciation and protein content has been determined to further characterize pollen solutions. Furthermore, the surface activity of SPPs has also been investigated by using pendant drop tensiometry. All studied SPP samples show critical supersaturation (SS Crit) values that are atmospherically relevant SS conditions. Hygroscopicity κ values are in the range characteristic of organic compounds (0.1–0.3). We found that organic speciation and protein content vary substantially among pollen types, with saccharides and fatty acids being the only organic compounds found in all pollen types. A clear relationship between SPP activation and its organic composition was not observed. This study also reveals that all SPPs investigated reduce the surface tension of water at high concentrations but at diluted concentrations (such as those of activation in the CCNC), the water surface tension value is a good approximation in Köhler theory. Overall, this analysis points out that pollen particles might be an important source of CCN in the atmosphere and should be considered in aerosol-cloud interactions processes.
Graphical abstract Display Omitted
Highlights Subpollen particles (SPPs) show κ values in the 0.1–0.3 range. SPPs activate as CCN at atmospheric supersaturation conditions. Saccharides and fatty acids are organic compounds found in all pollen types. The droplet surface tension reduction is observed at high concentration of SPPs. Reduction of surface tension does not show a relevant effect on SPP activation.
Cloud condensation nuclei activation properties of Mediterranean pollen types considering organic chemical composition and surface tension effects
Casans, A. (author) / Rejano, F. (author) / Maldonado-Valderrama, J. (author) / Casquero-Vera, J.A. (author) / Ruiz-Peñuela, S. (author) / van Drooge, B.L. (author) / Lyamani, H. (author) / Cazorla, A. (author) / Andrews, E. (author) / Lin, Jack J. (author)
Atmospheric Environment ; 310
2023-07-14
Article (Journal)
Electronic Resource
English