台北市空中孢粉每日的逐時變化

Diurnal Variations of Airborne Pollen and Spores in Taipei City, Taiwan

本研究以設在台北市市區的孢粉收集器（Burkard seven-day volumetric pollen trap）收集1993和1994兩年的空中孢粉，發現這兩年累計所有空中孢粉於一天出現的逐時變化（diurnal variation）趨勢相似，空中孢粉多數出現在清晨3時至10時，只有少數會出現在下午。今以出現最優勢的前10種空中孢粉的逐時變化分析，其中構樹屬（Broussonetia）、梣屬（Fraxinus）、莎欏屬（Cyathea）和禾本科（Gramineae）孢粉兩年的逐時變化趨勢相似，構樹屬和梣屬花粉多數出現在深夜至次日上午；莎欏屬孢子多數出現在上午至中午；禾本科花粉則多數出現在下午。重陽木屬（Bischofia）、柏屬（Juniperus）、野桐屬（Mallotus）、桑屬（Morus）、山黃麻屬（Trema）及蕁麻科（Urticaceae）的花粉兩年的逐時變化趨勢不規則。體積較大的孢粉逐時變化趨勢較規則，例如莎欏屬孢子和禾本科花粉；體積較小的花粉，逐時變化趨勢較不規則，例如重陽木屬、柏屬、野桐屬、桑屬、山黃麻屬及蕁麻科。構樹屬和梣屬花粉雖然體積小，但因花粉的來源很靠近孢粉收集器，而出現規則的逐時變化趨勢。空中孢粉逐時變化的規則性可能受到孢粉來源、孢粉大小及氣流所影響，即體積較小的孢粉較易受影響而使其逐時變化趨勢較不規則。

The diurnal variation of airborne pollen and spores in Taipei City, Taiwan, was investigated during a two-year survey from 1993 to 1994. The pollen and spores were sampled using a Burkard seven-day volumetric pollen trap. The diurnal trends of the total amount of pollen and spores in 1993 and in 1994 were similar to each other, and peaked at 3 to 10 o’clock. The diurnal patterns of airborne pollen and spores of Broussonetia, Fraxinus, Cyathea and Gramineae in 1993 were similar to those in 1994. High concentrations of Broussonetia and Fraxinus were obtained from midnight to the next morning. Cyathea spores peaked from morning till noon, and Gramineae peaked in the afternoon. The diurnal patterns of airborne pollen of Bischofia, Juniperus, Mallotus, Morus, Trema and Urticaceae in 1993 were different to those in 1994. Regular diurnal patterns also associated with the taxa, which produce large pollen or spores, such as Gramineae and Cyathea. In contrast, Bischofia, Juniperus, Mallotus, Morus, Trema and Urticaceae produce relatively small pollen and the diurnal patterns of their airborne pollen were found irregular. The source plants Broussonetia and Fraxinus were close to the collection site so the diurnal patterns of their airborne pollen were regular, suggesting that the diurnal fluctuations of the pollen or spores in air might be affected by the source of plants and the sizes of pollen or spores. The transportation of the smaller pollen or spores in air is probably more easily affected by instability of air currents; they are therefore more likely to exhibit irregular diurnal patterns.