上海大气颗粒物中糖类的组成、粒径分布及来源

为更好地理解大气颗粒物中糖类的来源及其环境影响,利用微孔撞击式采样器(MOUDI)采集了上海市宝山区2012年11月—2013年8月四季节代表性时段18 μm以下11个不同粒径段的大气颗粒物样品,利用硅烷化衍生和GC-MS对10种脱水糖、单糖和糖醇类化合物进行了分析. 结果表明:上海大气颗粒物中所检测的10种糖类化合物的质量浓度之和在春、夏、秋、冬四季采样期的平均值分别为120.3、104.0、292.9和206.0 ng/m3,脱水糖在秋、冬季占主导地位,单糖和糖醇的质量浓度在冬季最低. 绝大部分脱水糖存在于粒径≤1.8 μm的颗粒中,冬、夏季质量浓度最高的粒径段(峰值粒径)为>0.32~0.56 μm,而春、秋季峰值粒径为>0.56~1.0 μm. 单糖和糖醇类化合物在春、夏季时主要存在于粒径>1.8 μm的颗粒中,而秋、冬季时在粒径≤1.8 μm的颗粒中质量浓度较高. 应用PMF(正定矩阵因子分析法)解析出了大气颗粒物中糖类的3个来源——生物质燃烧、植物源土壤有机质和微生物源土壤有机质. 脱水糖全部来源于生物质燃烧,单糖主要来源于植物源土壤有机质,而糖醇主要来源于微生物源土壤有机质；秋、冬季时生物质燃烧对山梨糖醇之外的单糖和糖醇有较大贡献. 

Composition, Size Distribution and Sources of Saccharides in Atmospheric Particles in Shanghai

To better understand the sources and potential environmental impacts of particulate saccharides, aerosol samples of eleven size ranges from <0.056 μm to 18 μm were collected by a MOUDI sampler at Baoshan, Shanghai, during 2012 and 2013. Saccharides, including three anhydrosugars, four monosaccharides and three sugar alcohols were quantified with GC-MS after silylanization. The results showed that the average concentrations of ten quantified saccharides in the atmospheric particles in Shanghai were 120.3,4.0,2.9 and 206.0 ng/m3 in spring, summer, autumn and winter seasons, respectively. Anhydrosugars were the dominant species in particulate saccharides in autumn and winter. Concentrations of monosaccharides and sugar alcohols were the lowest in winter. Levoglucosan was almost exclusively present in the particles with diameters ≤1.8 μm in all seasons. Concentrations of levoglucosan peaked at the size range of >0.56-1.0 μm in spring and autumn, and of >0.32-0.56 μm in winter and summer. Generally, monosaccharides and sugar alcohols existed mainly in the particles with diameters >1.8 μm in spring and summer, while mainly in particles ≤1.8 μm in autumn and winter. Using positive matrix factorization, the sources for saccharides in atmospheric particles in Shanghai were identified as biomass burning, plant-originated soil organics and microbe-originated soil organics. Anhydrosugars uniformly originated from biomass burning, monosaccharides mainly came from plant-originated soil organics, and sugar alcohols were mainly caused by microbe-originated soil organics. Biomass burning substantially contributed to monosaccharides and sugar alcohols excluding sorbitol in autumn and winter.