Matthews Brianna H, Alsante Alyssa N, Brooks Sarah D
Department of Atmospheric Sciences, Texas A&M University, College Station, Texas 77843, United States.
Department of Oceanography, Texas A&M University, College Station, Texas 77843, United States.
ACS Earth Space Chem. 2023 Apr 27;7(6):1207-1218. doi: 10.1021/acsearthspacechem.3c00014. eCollection 2023 Jun 15.
Pollen grains significantly contribute to the aerosol population, and levels are predicted to increase in the future. Under humid atmospheric conditions, pollen grains can rupture creating pollen grain fragments referred to as subpollen particles (SPPs) which are dispersed into the atmosphere with wind. In this laboratory study, SPP emission factors were determined for ryegrass, sp., and giant ragweed,, in terms of the number of SPPs produced per pollen grain and the number of SPPs produced per m, which were compared to previously measured live oak,, emission factors. The SPP emission factors were 4.9 × 10 ± 4.3 × 10 SPPs per m for ryegrass, 1.3 × 10 ± 1.1 × 10 SPPs per m for giant ragweed, and 1.1 × 10 ± 1.6 × 10 SPPs per m for live oak. SPPs and whole pollen grains from these species were evaluated for their ice nucleation efficiency in immersion and contact mode freezing. Measurements of the ice nucleation efficiency indicate that SPPs are weakly effective INPs in immersion mode, but that pollen grains represent a source of moderately efficient INPs in immersion and contact modes.
花粉颗粒对气溶胶群体有显著贡献，并且预计未来其含量会增加。在潮湿的大气条件下，花粉颗粒会破裂产生被称为亚花粉颗粒（SPPs）的花粉颗粒碎片，这些碎片会随风散布到大气中。在这项实验室研究中，测定了黑麦草、豚草和大豚草的SPP排放因子，以每粒花粉产生的SPP数量和每平方米产生的SPP数量来衡量，并与先前测量的活橡树的排放因子进行比较。黑麦草的SPP排放因子为每平方米4.9×10±4.3×10个SPP，豚草为每平方米1.3×10±1.1×10个SPP，活橡树为每平方米1.1×10±1.6×10个SPP。对这些物种的SPP和完整花粉颗粒在浸入式和接触式冷冻中的冰核效率进行了评估。冰核效率的测量表明，SPP在浸入式模式下是弱效的冰核粒子，但花粉颗粒在浸入式和接触式模式下是中等效率冰核粒子的一个来源。
