Study on the Vegetative Detritus Contribution to Beijing Urban PM2.5 Using Cellulose as a Marker

Abstract

PM2.5 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 PM2.5 has been modified because of its low content in PM2.5 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 PM2.5 with a detection limit of 0.26 μg/m3. 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 PM2.5 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 PM2.5 is (0.573±0.17) μg/m3. The vegetative detritus contribution is 1.37%±0.65% of PM2.5 mass concentration, or 4.4% in average and 9.2% in the maximum of PM2.5 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 PM2.5 source identification.

Keywords

• atmospheric pm2.5
• marker
• cellulose determination
• vegetative detritus emission