長程傳輸對我國大氣中生物性微粒之影響

長程傳輸事件為大氣中生物性微粒的來源之一,其中沙塵事件以及生質燃燒事件為影響我國長程傳輸的主要來源。近年來我國相關調查皆以東亞沙塵為主,尚未有相關研究評估不同來源之長程傳輸事件對生物性微粒的影響。本研究於 2012 年 1~5 月利用高流量懸浮微粒採樣器在合歡山進行連續採樣,分析不同來源長程傳輸事件對高海拔大氣中真菌孢子及花粉濃度的影響。除此之外, 本研究亦探討樣本中化學元素濃度和真菌孢子與花粉的相關性。根據結果發現, 採樣期間共有沙塵事件 53 天(其中包含非東亞沙塵 37 天、東亞沙塵 16 天)以及生質燃燒事件 69 天。研究期間總真菌孢子的濃度平均值為 29513.98spores/1000m3, 其中最高濃度出現在三月初,次高峰則是在五月。優勢真菌包括 Aspergillus/Penicillium、Basidiospores、Cladosporium、Ascospores、Periconia 以及 Arthrinium。沙塵與生質燃燒事件影響期間優勢真菌的濃度皆顯著高於背景日,其中沙塵事件中非東亞沙塵對真菌的影響較東亞沙塵顯著。總真菌濃度與化學元素 As 及 Cl-的相關性較低(r =0.281、0.222),Mo 與 P 的相關性最高(r=0.645、0.639)。採樣期間花粉的總濃度平均值為 3038.32pollen grains/1000m3,濃度於三月底四月初達到高峰,在五月底達到次高峰。整體而言出現頻率最高的花粉種類依序為 Morus、Juniperus、Pinaceae、Trema、Alnus。總體而言花粉受長程傳輸事件的影響較真菌弱,長程傳輸事件前後達顯著差異的花粉僅占少數。觀察各月花粉濃度趨勢變化後,發現非東亞沙塵對於三月的花粉濃度影響最為明顯。總花粉濃度和 P 與 Mo 的相關性最強(r=0.578、0.591)。優勢花粉(Alnus、Juniperus、Morus、Myrica、 Pinaceae、Trema 和 Unidentified)與化學元素濃度間的相關性結果顯示,Mo 與 Trema 有最強的相關性(r=0.526), Cu 與 Myrica 出現顯著的負相關(r=-0.298)。本研究為第一個調查自由對流層中,不同類型長程傳輸事件對大氣中生物性微粒影響的研究。未來的研究可以利用分子生物學的技術,進一步分析生物性微粒的遺傳物質,以確認其長程傳輸的來源。此外,可以同時進行地面及高海拔地區大氣中化學元素與生物性微粒的監測,以瞭解長程傳輸事件對不同海拔高度的影響。

關鍵字

非東亞沙塵；東亞沙塵；生質燃燒；長程傳輸；生物性微粒；真菌孢子；花粉

並列摘要

Long-range transport, resulting mainly from dust storms and biomass burning, is one of the sources of ambient bioparticles in Taiwan. However, most researches in Taiwan investigated the contribution of East Asian dust. No study has been conducted to assess the impact of long-range transport events from different sources on ambient bioparticles. We conducted a study to monitor ambient bioparticles at Mt. Hohuan from January to May, 2012, using a high volume sampler to evaluate the contribution of different long range transport events to free tropospheric bioparticles. We also examined the relationships between chemicals and bioparticles (fungal spores and pollens) in the samples. According to our results, there were 53 days classified as dust event days (including 37 Non East Asian dust event days and 16 East Asian dust event days) and 69 days classified as biomass burning events during the sampling period. The average concentration of total fungal spores was 29513.98 spores/1000m3 during the study period, and the highest concentrations of fungal spores were recovered in March and May. The predominant fungal taxa were Aspergillus/Penicillium、Basidiospores、 Cladosporium、Ascospores、Periconia and Arthrinium. The fungal concentrations on the dust and biomass burning event days were significantly higher than those on the background days, and Non East Asian dust events had more significant influence on fungal composition than East Asian dust events. Total fungal levels had the highest positive correlations with Molybdenum (Mo) and Phosphorus (P) (r=0.645, 0.639), and lower correlations with Arsenic (As) and Chloride (Cl-) (r =0.281, 0.222). The average concentration of pollens was 3038.32 grains/1000m3during the study period, with the peaks observed at the end of March and early April, as well as in May. The predominant pollen taxa were Morus, Juniperus, Pinaceae, Trema and Alnus. Overall, the impacts of the long-range transport events on pollens were weaker than on fungal spores. Only a small number of pollens had significant differences between the event days and the background days. Examining the temporal variation of pollen concentrations during the study period, we found that African dust influenced the pollen concentration most obviously in March. Total pollen concentrations had the highest correlations with P and Mo (r=0.578, 0.591). Among the predominant pollen taxa (Alnus, Juniperus, Morus, Myrica, Pinaceae, Trema and Unidentified), Mo and Trema had the strongest positive iii correlation (r=0.526), and Copper (Cu) and Myrica had a significant negative correlation (r =-0.298). This is the first study to investigate the effects of different types of long-range transport events on bioparticles in the free troposphere. Future studies can further confirm the sources of long-range transported bioparticles using molecular biology techniques. Moreover, monitoring the chemical elements and bioparticles simultaneously at both high altitude and ground level will be helpful to understand the impact of long-range transport events at different altitudes.