秋收季节稻草燃烧粒子大气脱水醣类成分与粒径分布研究

以台湾中南部水稻作物区域为目标,探讨秋收稻草燃烧烟尘大气脱水醣类粒径分布成分特征;以改良离子层析仪解析3种大气悬浮粒子(PM2.5、PM10、总悬浮颗粒(TSP))大气脱水醣类成分浓度(左旋葡萄糖、甘露聚糖)与粒径分布,并探讨稻草燃烧对大气粒子的贡献率。结果显示,稻草燃烧期间大气(乡村/市郊)两种粒子(PM2.5与TSP)左旋葡萄糖浓度均大幅上升,两种粒子收成燃烧期间较非收成季节升高约5.5倍(较收成季节背景PM2.5与总悬浮颗粒分别高1.21倍与1.40倍)严重影响区域空气质量。市郊含左旋葡萄糖粒子分布以PM2.5细微粒为主(占TSP81%以上);乡村左旋葡萄糖粒径分布较广,PM2.5粒子占TSP56%左右,粗大粒子(PM>10)占总悬浮颗粒的35%。此外,结果显示稻草生物质燃烧对区域PM2.5粒子平均贡献率为12%,市郊稍高于乡村(乡村、市郊平均贡献率分别为10.5%、13.0%),显现稻草生物质燃烧对台湾中南部空气质量有严重影响。

Particle Size Characteristics of Anhydrosugars from Fall-harvest Season of Rice Straw Burning

In order to characterize the ambient anhydrosugar tracers derived from rice straw burning in fall-harvest season,three airborne particle-size ranges (PM2.5,PM2.5-10,and total suspended particle(TSP)) were collected simultaneously at two locations (countryside and suburban site) to investigate the variations of particle-size profiles of anhydrosugar tracers in the atmosphere. Additionally,the levoglucosan contribution ratios in PM2.5 particles from rice straw burning was also estimated. The results showed that the concentrations of anhydrosugars in both PM2.5 and TSP particles significantly increased during intensive burning periods (1.21 and 1.40 times higher than harvest-season background for PM2.5 and TSP particles,respectively). Furthermore,the size distribution of ambient levoglucosan at suburban site showed a high abundance concentration in PM2.5(81% of TSP), but it demonstrated a wide-range size distribution at countryside,constituted 56% and 35% in PM2.5 and PM>10 particles,respectively. Moreover,the measurements were applied to estimate the contribution ratio from rice straw burning to ambient PM2.5 particles,shown average contribution of 12% during fall-harvest burning season.