北京城区硬质地面近地空间树木花粉浓度日变化及小气候因子的影响

Diurnal Variation of Tree Pollen Concentration and Its Relation to Microclimate Factors on Hard Ground Surface in Beijing Urban Area

在油松开花初期、白皮松开花末期、臭椿开花盛期,分别测定硬质地面条件下不同树种在距树10m、高度1.5m处花粉浓度和小气候因子的变化,分析树木花粉浓度日变化特征及其与小气候因子的关系。结果表明:3个树种花粉浓度日变化呈现一致的"双峰型"变化曲线,峰值分别出现在14:00和20:00;花粉浓度日变化的规律性特征与空气温度、空气相对湿度、地面温度、光照强度等的变化密切相关;地面温度与花粉浓度第2高峰的发生时间相关性较大,硬质地面晚间积蓄地温形成的空气对流可能是导致20:00花粉浓度高峰的主要原因。硬质地面在一定程度上可加剧致敏花粉的危害程度。提出花粉污染防控和降低致敏风险的建议。

This article investigated diurnal variations of pollen dispersal and the relationship with microclimate factors during the flowering period of Pinus tabulaeformis,Pinus bungeana and Ailanthus altissima. Pollen concentrations of the three species were monitored at 10 m away from trunk of the sampling tree and 1. 5 m high above ground of hard ground surfaces. Results showed that： 1 ） Diurnal variations of pollen dispersal among three species had similar double-peak curves which presented at 14：00 and 20：00 on hard ground surface. 2） There was a significant relationship between pollen concentration and air temperature,air relative humidity,ground temperature,light intensity. 3 ） The ground temperature played a crucial role in the diurnal variations of pollen concentration and might be a decisive factor for the emergence of the second peak of pollen concentration. The heat stored in hard ground during the day would be slowly released at night,which could promote the air convection and hence be the main reason for the second peak of pollen concentration at 20：00. Compared with the soft ground,the airborne allergenic pollen showed much more harmful in the air near hard ground. In addition,tree species selection,urban surface condition,and timing for outdoor sports and activities were suggested.