How far can wind-borne pollen be disseminated?

Sack, S.Senior

doi:10.1016/0021-8707(49)90059-3

Cited by 9 publications

(1 citation statement)

References 5 publications

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“…Airborne pollen concentrations are measured to be anywhere between 10 and 1000 grains m −3 (Després et al, 2012) but can reach between 10 4 and 10 6 grains m −3 , particularly in the Northern Hemisphere spring months of April and May when many deciduous trees display peak pollen emissions (Steiner et al, 2015;Gregory, 1978). Pollen grains have been shown to reach altitudes of 3 km and above in the atmosphere (Diehl et al, 2001) and travel horizontal distances of up to ∼ 10 3 km (Sofiev et al, 2006;Hjelmroos, 1992;Sack, 1949). Individual small pollen grains can reside in the atmosphere for a few (generally 2-4) days (Sofiev et al, 2006), although pollen seasons can persist with high average concentrations (∼ 10 4 grains m −3 ) over many months, fluctuating with locality, season, time of day, and meteorology (Gregory, 1978).…”

Section: Introductionmentioning

confidence: 99%

Acoustic levitation of pollen and visualisation of hygroscopic behaviour

Mills,

Milsom,

Pfrang

et al. 2023

Atmos. Meas. Tech.

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Abstract. Pollen are hygroscopic; therefore, they have the potential to act as cloud condensation nuclei (CCN) in the atmosphere. This could have uncertain implications for cloud processes and climate as well as plant biodiversity and human health. Previous studies have investigated the hygroscopic swelling of pollen, linked to CCN activity by the κ-Köhler theory, using methods that follow observed mass increase by electrodynamic balance (EDB) or vapour sorption analyser. This study uses an acoustic levitator to levitate pollen grains in the true aerosol phase and uses a macroscope to image the pollen to investigate hygroscopic behaviour when relative humidity (RH) is changed. Two pollen species were studied in this work: Lilium orientalis (oriental lily) and Populus deltoides (eastern cottonwood). Both species were successfully levitated; however, the smaller Populus deltoides showed greater instability throughout experiments. The quality of images taken by the macroscope, and thus calculations of pollen area and aspect ratio, varied significantly and were sensitive to lighting conditions as well as to levitated pollen grain movement and orientation. Experiments with surface-fixed pollen grains were also conducted. They showed evidence that pollen hygroscopic swelling could be observed by the macroscope. The produced results were comparable with previously reported mass increase values. Although less accurate than methods that measure mass changes, the acoustic levitator and macroscope set-up offer an attractive alternative by virtue of being commercial, off-the-shelf, low-cost, and versatile techniques. A key advantage of this method is that it is possible to visually observe particle shape dynamics under varying environmental conditions.

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