摘要
2013年10月至2014年9月,在华北典型城市——河南新乡市市区采集4个季节大气PM_(2.5)样品,每个季节连续采样1个月,共获得样品124个。用热-光透射法(TOT)分析了PM_(2.5)中的碳质气溶胶组成,并用核磁共振(^(13)C-NMR)的方法测定了碳组分结构。采样期间PM_(2.5)、OC和EC的日平均质量浓度分别为(238±123)、(28.5±20.5)和(5.08±4.46)μg·m^(-3)。其中4个季节的TC与PM_(2.5)质量浓度高度相关,显示碳质气溶胶是新乡PM_(2.5)的重要组分,其季节平均质量浓度大小顺序为:冬季>秋季>春季>夏季。OC/EC比值在2.78~16.20之间,平均值为6.33,说明新乡碳质气溶胶来源具有多样性。不同季节OC/EC比值的变化范围也有不同,其中春季变化范围最小,说明污染源相对比较稳定;冬季变化范围最大,最低值为2.78,最高值为16.2,显示了生物质燃烧贡献的重要性。核磁共振结果显示新乡市碳质组分的主要成分为烷基碳、羟基碳、烷基取代的芳香碳和芳烃或者酚醛树脂类碳。秋季羧酸类碳和氧取代芳烃或者酚醛树脂类碳明显增加,显示了生物质燃烧对城市秋季大气碳质气溶胶贡献的重要性;冬季羟基化合物增加主要来源于室内生物质燃烧;春季芳香类化合物增加,可能为汽车尾气排放源;夏季烷烃类碳明显增加,与植物生长和气候有关。
PM2.5 were measured during October, 2013 to September, 2104 from Xinxiang city, China through continuous sampling campaign by collecting 124 samples of fine particulate matters. Carbonaceous components were quantified by thermal/optical transmission (TOT) method while compound composition was analyzed by solid-state nuclear magnetic resonance (13C-NMR) spectroscopy. Results for the mass concentration of PM2.5, OC and EC were found (238±123), (28.5±20.5) and (5.08±4.46)μg·m-3, respectively which revealed a significant correlation between PM2.5 and TC (TC=OC+EC), and indicated prime role of carbonaceous aerosol on the formation of fine particles. The highest concentrations of PM2.5, OC and EC were observed in winter followed by autumn and spring while lowest concentrations were observed in summer. OC/EC ratio (mean: 6.33) was found in range of 2.78~16.20, which indicated the diversity in source carbonaceous aerosol. Variation range for OC/EC ratio was observed lowest during spring season and reflected a relatively stable pollution source, on the other hand maximum variation range of OC/EC was observed in winter (2.78~16.2) which indicated the role of biomass burning as pollution source. Results of13C-NMR showed that organic in Xinxiang atmospheric aerosol particles is mainly composed of alkyl, Hydroxyl, alkyl-substituted aromatic and oxygen-substituted aromatic or phenolic functional groups. Increased carboxylic or oxygen-substituted aromatic or phenolic and hydroxyl functional group indicated the straw combustion in autumn and domestic fireplace biomass burning in winter, respectively. Aromatic compounds were found higher in spring season, which mainly from vehicle emission while increased alkyl compounds in summer season perhaps due to the weather and plant growth.
出处
《生态环境学报》
CSCD
北大核心
2016年第3期458-463,共6页
Ecology and Environmental Sciences
基金
广州市科学研究专项重点项目(201504010002)
关键词
华北
PM2.5
碳质气溶胶
核磁共振
OCEC
季节变化
Huabei
PM2.5
carbonaceous aerosol
13C-nuclear magnetic resonance
OC EC
seasonal variation
