Stable C and N isotopes of PM2.5 and size-segregated particles emitted from incense stick and cigarette burning

This work measured the 813C and 815N signatures in PM2.5 and size-segregated particles emitted from incense stick and cigarette burning in different brands or nicotine contents for pollution source identification indoors. Three popular brands of incense stick and cigarette were selected for experiments. A personal environmental monitoring sampler and a Sioutas cascade impactor were used to collect PM2.5 and size-segregated particles, respectively, for isotopic signatures analyses. Our data showed that both 813C and 815N values were heavier from incense stick burning (813C: 27.3 +/- 0.5; 815N: 8.63 +/- 1.35) than cigarette (813C: 28.5 +/- 0.2; 815N: 4.15 +/- 0.69). The scatter plots of 813C and TC/PM2.5 and of 815N and TN/PM2.5 can be applied to distinguish particle pollution sources and assess the influence of cigarette burning to PM2.5 according to different nicotine contents. The 813C values in size-segregated particles were similar to incense stick or cigarette burning; the 813C values in PM2.5 were significantly higher than those in size-segregated particles. However, the nitrogen amount was too low in most of the size-segregated particles to analyze 815N from incense stick and cigarette burning. These results suggest that the delta 13C signatures on PM2.5 cannot represent the isotopic characteristics of size-segregated particles and 815N has limitation for pollution source identification of different particle sizes.