Seasonal variations of airborne pollen in Beijing, China and their relationships with meteorological factors

An aeropalynological study was preformed in Chongwen district of Beijing, China during one year (from 21, March 2006 to 20, March 2007). A total of 1670 pollen grains from 37 taxa were identified. Two separate peaks of airborne pollen occurred during one year: one was related to the presence of the trees/shrubs pollen (Cupressus L., Pinus L., Populus L., Betula L., Corylus L., Salix L., Juglans regia L., Fraxinus L., Anacardiaceae and Livistona chinensis (Jacq.) R.Br.) in March, the other was attributed to herbaceous pollen (Artemisia L., Chenopodiaceae, Gramineae, Humulus L. and Labiatae) in September. Only a few pollen grains were found from December to next January. Results indicated that airborne pollen composition was consistent with the vegetation components and the pollination periods of the plants in the sampling site. The variations of pollen numbers were affected positively by temperature, negatively by relative humidity and precipitation. Stable wind speed seemed to have little effect on the fluctuation of the pollen number during the study period.