TY - JOUR

T1 - Water uptake of subpollen aerosol particles

T2 - Hygroscopic growth, cloud condensation nuclei activation, and liquid-liquid phase separation

AU - Mikhailov, Eugene F.

AU - Pöhlker, Mira L.

AU - Reinmuth-Selzle, Kathrin

AU - Vlasenko, Sergey S.

AU - Krüger, Ovid O.

AU - Fröhlich-Nowoisky, Janine

AU - Pöhlker, Christopher

AU - Ivanova, Olga A.

AU - Kiselev, Alexey A.

AU - Kremper, Leslie A.

AU - Pöschl, Ulrich

N1 - Publisher Copyright: © Author(s) 2021. This work is distributed under the Creative Commons Attribution 4.0 License.

PY - 2021/5/7

Y1 - 2021/5/7

N2 - Pollen grains emitted from vegetation can release subpollen particles (SPPs) that contribute to the fine frac tion of atmospheric aerosols and may act as cloud con densation nuclei (CCN), ice nuclei (IN), or aeroallergens. Here, we investigate and characterize the hygroscopic growth and CCN activation of birch, pine, and rapeseed SPPs. A high-humidity tandem differential mobility analyzer (HHT DMA) was used to measure particle restructuring and wa ter uptake over a wide range of relative humidity (RH) from 2 % to 99.5 %, and a continuous flow CCN counter was used for size-resolved measurements of CCN activa tion at supersaturations (S) in the range of 0.2 % to 1.2 %. For both subsaturated and supersaturated conditions, effective hygroscopicity parameters, κ, were obtained by Köh ler model calculations. Gravimetric and chemical analyses, electron microscopy, and dynamic light scattering measure ments were performed to characterize further properties of SPPs from aqueous pollen extracts such as chemical com position (starch, proteins, DNA, and inorganic ions) and the hydrodynamic size distribution of water-insoluble material. All investigated SPP samples exhibited a sharp increase of water uptake and κ above ∼ 95 % RH, suggesting a liquid liquid phase separation (LLPS). The HHTDMA measure ments at RH > 95 % enable closure between the CCN activation at water vapor supersaturation and hygroscopic growth at subsaturated conditions, which is often not achieved when hygroscopicity tandem differential mobility analyzer (HT DMA) measurements are performed at lower RH where the water uptake and effective hygroscopicity may be limited by the effects of LLPS. Such effects may be important not only for closure between hygroscopic growth and CCN activation but also for the chemical reactivity, allergenic potential, and related health effects of SPPs.

AB - Pollen grains emitted from vegetation can release subpollen particles (SPPs) that contribute to the fine frac tion of atmospheric aerosols and may act as cloud con densation nuclei (CCN), ice nuclei (IN), or aeroallergens. Here, we investigate and characterize the hygroscopic growth and CCN activation of birch, pine, and rapeseed SPPs. A high-humidity tandem differential mobility analyzer (HHT DMA) was used to measure particle restructuring and wa ter uptake over a wide range of relative humidity (RH) from 2 % to 99.5 %, and a continuous flow CCN counter was used for size-resolved measurements of CCN activa tion at supersaturations (S) in the range of 0.2 % to 1.2 %. For both subsaturated and supersaturated conditions, effective hygroscopicity parameters, κ, were obtained by Köh ler model calculations. Gravimetric and chemical analyses, electron microscopy, and dynamic light scattering measure ments were performed to characterize further properties of SPPs from aqueous pollen extracts such as chemical com position (starch, proteins, DNA, and inorganic ions) and the hydrodynamic size distribution of water-insoluble material. All investigated SPP samples exhibited a sharp increase of water uptake and κ above ∼ 95 % RH, suggesting a liquid liquid phase separation (LLPS). The HHTDMA measure ments at RH > 95 % enable closure between the CCN activation at water vapor supersaturation and hygroscopic growth at subsaturated conditions, which is often not achieved when hygroscopicity tandem differential mobility analyzer (HT DMA) measurements are performed at lower RH where the water uptake and effective hygroscopicity may be limited by the effects of LLPS. Such effects may be important not only for closure between hygroscopic growth and CCN activation but also for the chemical reactivity, allergenic potential, and related health effects of SPPs.

KW - SECONDARY ORGANIC AEROSOL

KW - ICE NUCLEATING ABILITY

KW - THUNDERSTORM ASTHMA

KW - RELATIVE HUMIDITIES

KW - AMMONIUM-SULFATE

KW - SURFACE-TENSION

KW - RAIN-FOREST

KW - PART 1

KW - POLLEN

KW - PROTEINS

UR - http://www.scopus.com/inward/record.url?scp=85105633047&partnerID=8YFLogxK

U2 - 10.5194/acp-21-6999-2021

DO - 10.5194/acp-21-6999-2021

M3 - Article

AN - SCOPUS:85105633047

VL - 21

SP - 6999

EP - 7022

JO - Atmospheric Chemistry and Physics

JF - Atmospheric Chemistry and Physics

SN - 1680-7316

IS - 9

ER -