Diurnal variation of tree pollen in the air in finland

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Abstract
The pollen was collected with Burkard spore traps in Turku and Jyväskylä, in southern and central Finland. Selected days of high concentration were analysed for hour to hour concentrations. The diurnal variation of pollen concentration was variable in Alnus, Betula, Juniperus and Pinus, while Picea, Populus, Quercus, Salix and Ulmus had regular daytime maxima och nightly minima. The pollen concentrations were closely correlated with increasing temperatures and decreasing relative humidities. A significant relationship with wind speed was also found, except in Alnuts and Betula. The most significant relationships with wind speed were found in Salix and Quercus, the pollen of which tends to remain in lumps. Generally, the bigger the pollen grains are, the more their concentrations are dependent on wind speed. Pinus and Picea seem to have a threshold wind speed about 4 m/s above which concentrations become higher.