| 摘要: | 本研究探討民俗節慶大氣增量潛勢及化學組成特性變異，針對元宵節慶之前中後期，在近於鹽水蜂炮施放活動源鹽水武廟會館頂樓及活動潛在下風處臺南鹽水國中頂樓，進行大氣氣膠同步採樣集研究，主要探討氣膠物種的無機鹽類、羧酸、醣醇類、脫水醣類、有機碳之特性，以瞭解臺灣鹽水蜂炮活動期間的大氣環境氣膠化學組成及粒徑分布特性。
研究期間位於鹽水國中PM2.5無機鹽類全日平均濃度高低分別為SO42- > NO3- > NH4+ > K+ > Cl-，與一般都市大氣環境相似，以光化產物為氣膠主要組成，然而元宵節蜂炮活動當晚，鹽水國中及武廟的PM2.5中發現含高濃度的K+，分別為元宵節前期的98.6及24.3倍，及高濃度Cl-為元宵節前期的17.2倍及4.6倍，並在代表活動下風處的鹽水國中呈現PM2.5氣膠K+及Cl-的巨大增量。此外，PM2.5之Ca2+、Mg2+、NO3-及nss-SO42- (non-sea salt sulfate)濃度皆較元宵節活動前期上升，甚至僅在元宵節當晚發現高濃度的Sr2+、Ba2+及CrO42-，顯示元宵節煙火炮竹的燃放不僅使上述一般無機鹽類濃度明顯上升且有特殊金屬鹽類的出現。無論元宵節前後及蜂炮施放期間鹽水區域大氣PM2.5及PM10羧酸均以oxalate, lactate及acetate為主要物種，但在鹽水國中PM2.5及PM10的maleate濃度從元宵節前期平均的6.9±2.6 ng/m3、9.8±9.6 ng/m3增加至元宵節當晚的404.8 ng/m3、934.6 ng/m3，雖然元宵節期間以東北風為盛行風向，代表蜂炮活動上風處的鹽水武廟PM2.5及PM10的maleate濃度亦有88.7%及41.7%的濃度增量，但相較下風處的鹽水國中，其maleate濃度較元宵節前明顯增加了近58倍及95倍，顯示蜂炮活動期間大量煙火炮竹的燃放使環境氣膠特定物種明顯增量，也發現Sr2+、Ba2+、CrO42-及maleate等煙火燃放微粒的重要指標物種。再者，代表生質燃燒物種之levoglucosan在活動當晚的鹽水國中，PM2.5及PM10微粒levoglucosan濃度分別為246.9 ng/m3及588.8 ng/m3，為元宵活動前的16.0倍及12.9倍，而元宵節當晚的鹽水國中PM2.5及PM10微粒levoglucosan濃度分別為上風處的鹽水武廟的2.39及2.56倍，顯示元宵節慶鹽水蜂炮排放燃燒爆竹所含生質包材纖維及材料的燃燒特定指標物種，在元宵節期間有明顯增量貢獻。
元宵節期間鹽水武廟及鹽水國中之氣膠質量濃度增量主要在0.18~1.8 μm的粒徑範圍，尤其在粒徑0.54~1.0 μm的質量濃度為元宵節前的6~7倍，而鹽水國中在粒徑0.54 μm的微粒質量濃度較上風處的鹽水武廟高出78.6%，明顯受蜂炮煙火排放增量所影響，其中氣膠的Na+、Cl-、K+、Mg2+、Ca2+及nss-SO42-的濃度粒徑分布多在submicron droplet mode (0.32~1.0 μm) 及micron droplet mode (1.0~2.5 μm)有明顯增量。比較元宵節前已顯著存在submicron droplet mode粒徑範圍的光化產物nss-SO42-及oxalate，生質燃燒指標之物種levoglucosan在元宵節前的低濃度，但在元宵節期間此三物種在0.32~1.0 μm的submicron droplet mode同步增量，顯示此時的nss-SO42-及oxalate的增量為蜂炮煙火微粒的原生性組成，尤其levoglucosan在0.54~1.0 μm的濃度增量近13倍，元宵節後levoglucosan又逐漸回復至元宵節前的濃度概量，而大氣氣膠組成在元宵節後仍以nss-SO42-及oxalate為主要物種，顯示元宵節期間大氣光化產物與元宵節節慶燃放蜂炮煙火的原生產物同時累存在submicron droplet mode的粒徑範圍。此外，鹽水元宵蜂炮煙火氣膠存在特殊金屬鹽類Sr2+及Ba2+濃度分布主要在micron droplet mode及submicron droplet mode粒徑範圍，對近距離參與及觀看蜂炮煙火施放的遊客與當地居民存在潛在的健康風險。
Abstract
This study investigated the incremental potential and the characteristic variation of chemical composition in the atmosphere during the pre-lantern festival (pre-LF), lantern festival (LF), and post-LF periods on the rooftop of Yanshuei Martial Temple (the Temple), where beehive fireworks were displayed, and at the rooftop of the Yanshuei Junior High School (the School), which was on the lee side of the display. Aerosol samples at both sites were collected at the same time for research. The aerosol compounds focused on in this study included inorganic species, carboxylates, sugar alcohols, anhydrosugars, and organic carbon. The aim of this study was to identify the aerosol chemical species and assess the particle size distribution during the beehive firework display in Yanshuei, southern Taiwan.
During the research period, the mean concentrations of inorganic salts in PM2.5 for an entire day were SO42− > NO3− > NH4+ > K+ > Cl−, which was similar to that of the general city atmosphere in that the main components of aerosols were photochemical products. In the evening of the LF beehive firework display, high concentrations of K+ in PM2.5 were observed in the School and the Temple, 98.6 and 24.3 times higher than pre-LF, respectively. Likewise, concentrations of Cl− at the two locations were also detected to be 17.2 and 4.6 times as high as its pre-LF values, respectively. These discoveries indicated substantial increases in aerosol K+ and Cl− in PM2.5 at the school, which was located on the lee side of the display. Additionally, Ca2+, Mg2+, NO3−, and nss-SO42− (non-sea salt sulfate) in PM2.5 were all higher than in pre-LF. In the evening of LF, high concentrations of Sr2+, Ba2+, and toxic CrO42− were surprisingly detected, demonstrating that the LF firework display substantially increased the aforementioned general inorganic salt concentrations but also created special metallic salts. In the Yanshuei area, the primary species of carboxylates in PM2.5 and PM10 pre-LF, LF, and post-LF were all oxalate, lactate, and acetate. At the school, however, the maleate concentration in PM2.5 and PM10 increased from the average of 6.9 ± 2.6 ng/m3 and 9.8 ± 9.6 ng/m3 pre-LF to 404.8 ng/m3 and 934.6 ng/m3 during the LF, respectively. Although the wind was predominately blowing from the northeast during the LF, the temple upwind from the beehive firework display still exhibited an 88.7% and 41.7% increase in maleate concentration in PM2.5 and PM10, respectively. By contrast, the school, which was downwind from the display, exhibited an increase of nearly 58 times and 95 times the original maleate concentration, indicating that during the beehive activity, the burning of a large quantity of fireworks increased the amount of specific aerosol species in the environment. Additionally, indicator species of firework burning were detected, including Sr2+, Ba2+, toxic CrO42− and maleate. Levoglucosan, which is indicative of biomass burning, exhibited concentrations in PM2.5 and PM10 of 246.9 ng/m3 and 588.8 ng/m3 in LF, which were 16.0 and 12.9 times higher than their pre-LF values, respectively. During the LF, the levoglucosan concentration in PM2.5 and PM10 at the school was 2.39 and 2.56 times higher than that at the temple upwind, indicating that the composition of the beehive firework burned during the festival included biomaterial wrapping fiber and specific indicator species, the prevalence of which substantially increased during the LF.
Moreover, the increases in aerosol mass concentration during the LF in both sites were primarily reflected in the particles ranging from 0.18 μm to 1.8 μm in size. In particular, the mass concentration of particles with a size of 0.54–1.0 μm increased to 6–7 times to its value pre-LF. The mass concentration of particles with a size of 0.54 μm at the school was 78.6% higher than at the temple upwind, which clearly indicated the influence of the beehive firework display. The particle distribution of Na+, Cl−, K+, Mg2+, Ca2+, and nss-SO42− in the aerosol was primarily increased in the submicron droplet mode (0.32–1.0 μm) and the micron droplet mode (1.0–2.5 μm). Different from the photochemical products nss-SO42− and oxalate, which had comprised substantial parts of pre-LF aerosol in the submicron droplet mode, levoglucosan, an indicator species of biomass burning, originally had a low concentration. However, the quantity of all of these three species increased during the LF in the submicron droplet mode with a size of 0.32–1.0 μm. This indicated that at this time, the increase in nss-SO42− and oxalate production was caused by submicron particles emitted during the beehive firework display. The concentration of levoglucosan in the range of 0.54–1.0 μm increased by nearly 13 fold and then gradually decreased to the pre-LF level after the festival. The major components in the post-LF aerosols were still primarily nss-SO42− and oxalate, indicating that during LF, the photochemical products in the atmosphere and the original products from beehive firework burning are both accumulated in the range of the submicron droplet mode. In addition, aerosols collected from the Yanshuei LF beehive firework display contained special metal salts Sr2+ and Ba2+, which primarily fell in the micron droplet mode and the submicron droplet mode in terms of particle size. Such species pose potential health threats to tourists and local residents who participated or viewed the beehive firework in close proximity.
Keywords: Lantern festival, Yanshuei Junior High School, Yanshuei Temple, beehive firework, festival aerosol, inorganic salts, carboxylates, anhydrosugars, particle size distribution, incremental potential |
