Pollution Characteristics and Source Analysis of n-alkanes and Saccharides in PM2.5 During the Winter in Liaocheng City

Abstract

To investigate molecular composition, mass concentrations, and sources of n-alkanes and sugars which are adsorbed in ambient particulate matters in Liaocheng City during winter, PM2.5 samples were collected from January 17 to February 15, 2017 at Liaocheng University. 19 kinds (C18-C36) of n-alkanes and 10 kinds of sugars were determined using GC-MS. The identification of n-alkane and sugar sources were investigated using principal component analysis (PCA). The results showed that the mass concentrations of total n-alkanes in PM2.5 during the winter were (456.9±252.5) ng·m-3. During the haze period, the concentrations of n-alkanes were two times higher than those on clear days. Additionally, the concentrations of n-alkanes during fireworks event I and fireworks event Ⅱ were 0.9 times and 1.2 times higher than those on clear days. During the sampling period, the Carbon preference index (CPI) was 1.2±0.1, and the contribution from plant wax concentrations for n-alkanes (% Wax Cn) was between 3.1%~36.0%, indicating that fossil fuels were the major source of n-alkanes in Liaocheng City during the winter. The mass concentrations of saccharides in PM2.5 during the winter were (415.5±213.8) ng·m-3. Levoglucosan was the most abundant species, followed by galactosan and mannosan, which accounted for more than 91.6% of total saccharides, indicating that biomass burning was much more significant in Liaocheng City. PCA further suggested that n-alkane and saccharide compounds in atmospheric aerosol during the winter in Liaocheng City were primarily derived from fossil fuel and biomass burning.