摘要
大气细粒子(PM2.5)污染是全球尤其是我国许多城市的重要环境问题。利用示踪物质识别和估算大气颗粒物来源是公认的可靠技术,纤维素可以作为示踪物质表征一次颗粒物的天然植被排放来源。本文针对大气细粒子中纤维素含量低、全程序空白相对较高等难点,优化建立了纤维素酶水解、GOD-苯酚-四氨基安替比林测糖法,在我国首次应用于测定大气PM2.5中纤维素的含量,估算天然植被排放源的贡献。方法检出限为0.26μg/m3(纤维素),可以满足大气PM2.5纤维素测定要求;而且有效地降低了空白,全程序空白值(36.5μg葡萄糖)低于文献方法空白值(53.8μg葡萄糖),使之更适合于PM2.5的测定。使用本方法对2012年5月至6月采集的北京市大气PM2.5样品进行分析,纤维素检出率为96%,纤维素的平均含量为(0.573±0.17)μg/m3,折合为天然植被排放量占PM2.5质量浓度的1.37%±0.65%;天然植被排放源对有机碳的平均贡献率为4.4%,最大达到9.2%,反映出天然植被排放是北京市PM2.5的重要来源之一。本研究方法为我国城市大气颗粒物(包括总悬浮颗粒物、PM10、PM2.5等)来源识别提供了新的手段。
PM 2.5 pollution raises environmental concern in China and other countries worldwide.The marker technique is regarded as a reliable tool for atmospheric aerosol source tracing.Cellulose can be used as a marker to identify and evaluate vegetative detritus emission to primary aerosols.An analytical method for cellulose in the PM 2.5 has been modified because of its low content in PM 2.5 and the relative high procedure blank.The method combines an enzymatic cellulose hydrolysis procedure and a GOD-phenol-4-aminoantipyrene determination of formed glucose.The key parameters of the method were optimized as a delignification condition,temperature for cellulose enzymatic hydrolysis,amount of enzyme,pH value and hydrolysis reaction time.The method meets the requirements of cellulose determination of PM 2.5 with a detection limit of 0.26 μg / m 3.A procedure blank of 36.5 μg glucose was obtained which is significantly lower than 53.8 μg for the previous method.Cellulose in 23 Beijing urban PM 2.5 collected from May 15th to June 28th,2012 were analyzed.The detection rate of cellulose is 96%. The results show that the cellulose concentration in Beijing PM 2.5 is（0.573 ± 0.17） μg / m 3.The vegetative detritus contribution is 1.37% ± 0.65% of PM 2.5 mass concentration,or 4.4% in average and 9.2% in the maximum of PM 2.5 organic carbon,indicating vegetative detritus is a major contributor of urban aerosol organic carbon and has to be considered in source attribution studies.This method provides a new technique for urban atmospheric PM 2.5 source identification.
出处
《岩矿测试》
CAS
CSCD
北大核心
2013年第5期738-746,共9页
Rock and Mineral Analysis
基金
国家自然科学基金面上项目(21077134)
科技部创新方法工作专项项目(2009IM030200)
