| 摘要: | 本研究探討民俗節慶鹽水蜂炮活動之大氣氣膠化學組成之特性變異，採集臺南市鹽水區元宵節慶前後時期大氣狀物及氣膠微粒，於鹽水蜂炮活動源附近之鹽水武廟附設會館頂樓及潛在下風處鹽水國中頂樓進行採樣，主要探討氣膠中無機鹽類、羧酸、醣類、醣醇類、脫水醣類、有機碳之化學組成與其生成來源及粒徑分佈之特性，以瞭解鹽水蜂炮節慶活動對當地空氣品質所帶來的影響。
元宵節當天大氣氣狀物之全日平均濃度高低為NH3 > HCl > SO2 > HNO3 >HNO2 > Oxalic acid，其中NH3、HCl、SO2、HNO3、Oxalic acid均為日間大於夜間，顯示日間人為活動與自然排放較高，而HNO2為夜間大於日間，顯示日間之HNO3為HNO2經由光化轉變而成。元宵節當天鹽水武廟PM2.5無機鹽類全日平均濃度以NO3-、SO42-、NH4+為主，鹽水國中以SO42-、K+、NO3-為主，元宵節當天夜晚鹽水武廟因燃放煙火及炮竹導致K+、Ca2+、Cl-、NO3-、SO42-、PO43-濃度明顯增量，而鹽水國中PM2.5中的K+、Mg2+、Cl-、NO3-、SO42-濃度有明顯增量，其中以K+的濃度兩地分別為元宵節之前夜晚的2.19及15.5倍，顯示元宵節煙火炮竹的燃放活動會使上述物種濃度明顯上升，尤以K+最為顯著。元宵節當天鹽水武廟PM2.5氣膠羧酸以oxalate、acetate及lactate為主要物種，鹽水國中以lactate、succinate及acetate為主要物種，其中最為特殊增量之物種maleate在活動當天夜晚濃度分別為元宵節之前夜晚鹽水武廟及鹽水國中的1.96、4.09倍，顯示活動當天大量燃放煙火及炮竹使特定物種maleate濃度提升，故為煙火炮竹燃燒之重要指標物種，malonate/succinate (M/S)於元宵節當天鹽水武廟及鹽水國中之比值分別為0.60及0.29，而acetate/formate (A/F)的比值分別為2.81及4.21，顯示元宵節當天之大氣氣膠皆受到生質燃燒及交通排放影響。代表生質燃燒指標物種的levoglucosan在活動當天兩地的濃度分別為元宵節之前的1.45及3.41倍，顯示元宵節慶燃放煙火炮竹將其中生質材料貢獻在大氣中，而levoglucosan/mannosan (L/M)之比值兩地分別為1.03及0.83，當天夜晚為1.16及1.62，顯示生質燃燒來源種類主要為纖維素，其中較為特別之物種trehalose在元宵節兩天夜晚下風處之鹽水國中PM2.5的濃度降為元宵節之前夜晚的0.25及0.78倍，顯示元宵節夜晚活動由於大量的煙火及炮竹燃放抑制了生物氣膠。
元宵節當天氣膠質量濃度主要在droplet mode及coarse mode粒徑範圍明顯增長，其中Cl-、K+、Mg2+、nss-SO42-的粒徑分布皆在droplet mode及coarse mode有明顯增量，顯示元宵節慶燃放煙火及炮竹對於上述物種粒徑分布的增量主要在droplet mode及coarse mode。元宵節當天鹽水武廟nss-SO42-、oxalate、 levoglucosn主要粒徑範圍皆為droplet mode，顯示元宵節當天鹽水武廟nss-SO42-、oxalate、levoglucosn的大氣光化產物與活動源燃放之煙火及炮竹產生的微粒原生性組成同時存在於droplet mode。
元宵節當天下風處之鹽水國中各mode的氣膠NR值為所有時期最酸性，顯示元宵節當天燃放煙火及炮竹會產生較多的致酸性物質nss-SO42-及NO3-，而元宵節當天鹽水武廟氣膠NR plus Ca2+值除了coarse mode為酸性，其餘各mode的氣膠NR plus Ca2+值皆為中性偏鹼，顯示Ca2+在氣膠當中具有致鹼能力。
This study investigated the chemical compositional variation of gaseous substances and aerosol particles during the Yanshui Beehive Fireworks in Taiwan, an event that coincided with the Lantern Festival. Gaseous substances and aerosol particles were collected before and after the Lantern Festival on the top floor of the affiliated guest house of the Yanshui Martial Temple where the Yanshui Beehive Fireworks was held, as well as on the top floor of Tainan Municipal Yanshuei Junior High School, which was a potential area that the gaseous substances and aerosol particles might spread to. The objective was to investigate the chemical composition of aerosol particles (inorganic salts, carboxylates, carbohydrates, sugar alcohols, anhydrosugars, and organic carbon) and their size distribution to understand the influence of Yanshui Beehive Fireworks on local air quality.
On the day of Lantern Festival, the gaseous substances ranked in a descending order according to their daily average concentration were NH3 > HCl > SO2 > HNO3 > HNO2 > oxalic acid. The concentrations of NH3, HCl, SO2, HNO3, and oxalic acid were higher at day time than at night time, indicating that these substances were mostly from natural emissions and human activities at the day time. Moreover, the HNO2 concentration was higher at night time than at day time. This was because HNO2 was converted into HNO3, the concentration of which was higher at day time, through photochemical reaction; the absence of photochemical reaction at night prevented HNO2 from being converted and allowed a considerable amount of it to remain in the atmosphere. On the day of Lantern Festival at the Yanshui Martial Temple, NO3-, SO42-, and NH4+ were the inorganic–salt PM2.5 particles with the highest daily average concentration, whereas at the Yanshuei Junior High School, SO42-, K+, and NO3- showed the highest concentration. In the evening of Lantern Festival when fireworks and beehive rockets were launched at the Yanshui Martial Temple, aerosol particles K+, Ca2+, Cl-, NO3-, SO42-, and PO43- showed substantial increase in their concentrations; at the Yanshuei Junior High School, the concentrations of K+, Mg2+, Cl-, NO3-, and SO42-, in PM2.5 also increased substantially. In particular, the concentrations of PM2.5 K+ at these two locations in the evening of Lantern Festival were 2.19 and 15.5 times higher than in the evening on the previous day, respectively. This indicates that the beehive fireworks caused the concentrations of aerosol particles to increase considerably, and the increase was particularly significant in K+. Furthermore, oxalate, acetate, and lactate were the main species of carboxylates in PM2.5 aerosols at the Yanshui Martial Temple on the Lantern Festival day, while lactate, succinate, and acetate were the primary species at the Yanshuei Junior High School. The maleate concentrations at the Yanshui Martial Temple and Yanshuei Junior High School in the evening of Lantern Festival were 1.96 and 4.09 times higher, respectively, than those in the previous evening. This indicates that the large amount of fireworks and firecrackers caused the maleate concentration to increase; maleate can be viewed as a crucial indicator for the burning of fireworks and firecrackers. In addition, the ratios of malonate/succinate (M/S) at the Yanshui Martial Temple and Yanshuei Junior High School were 0.60 and 0.29, respectively, while the ratios of acetate/formate (A/F) were 2.81 and 4.21, respectively. This implicates that the atmospheric aerosol concentrations on the Lantern Festival were simultaneously affected by biomass burning and traffic emissions. Levoglucosan, an indicator substance of biomass burning, had a concentration that was 1.45 and 3.41 times higher at the two locations on the Lantern Festival than the previous day, revealing the substantial contribution of biomass burning on the Lantern Festival. Moreover, the ratios of levoglucosan/mannosan (L/M) at the two locations were 1.03 and 0.83 on the entire day of Lantern Festival but became 1.16 and 1.62 at the night time, indicating that the biomass that was burnt originated from the mixed materials of cellulose and hemicellulose. However, on the two nights of the Yanshui Beehive Fireworks, the concentrations of trehalose, a metabolite released by microorganisms, were only 0.25 and 0.78 times the concentration on the previous night of the Festival at the Yanshuei Junior High School, a location that was downwind from where the fireworks were launched. This may be because the large amount of fireworks and firecrackers inhibited the biological activity of bioaerosols.
On the day of Lantern Festival, the mass concentration of aerosol particles substantially increased within the size range of droplet and coarse modes. In addition, the concentration and size distribution of Cl-, K+, Mg2+, and nss-SO42- also showed a substantial increase in both droplet and coarse modes. This implicates that the burning of fireworks and firecrackers primarily affected the size distribution of the aforementioned particles in the droplet and coarse modes. The ranges of concentration and size of nss-SO42-, oxalate, and levoglucosn at the Yanshui Martial Temple were both in the droplet mode, indicating that the atmospheric photochemical products and primary particulate matters (i.e., ‒nss-SO42-, oxalate, and levoglucosn) produced by beehive fireworks burning at the Yanshui Martial Temple were all in the droplet mode.
The neutralization ratios of aerosol particles in each particle size mode at the Yanshuei Junior High School indicated that the aerosol particles had the highest acidity on the day of Lantern Festival, which primarily resulted from the large amount of acidic substances nss-SO42- and NO3- produced by firework and firecracker burning. Furthermore, the NR plus Ca2+ of aerosol particles at the Yanshui Martial Temple on the Lantern Festival day indicated that the particles were acid in the coarse mode but were neutral and alkaline in other size modes. This demonstrates that Ca2+ has the ability to result in alkalinity in aerosol particles.
In conclusion, atmospheric aerosol particles increased substantially during the Yanshui Beehive Fireworks, and K+, nss-SO42-, and levoglucosan in the droplet mode made significant contribution to such increase. Air quality was affected simultaneously by atmospheric photochemical products, primary biomass burning, and traffic emissions. The substantial decrease of trehalose concentration demonstrated that the biological activity of the bioaerosols was temporarily inhibited by the burning of beehive fireworks, forming a microscopic representation of the atmospheric environment during the festive period. |
