聊城市冬季PM_(2.5)中正构烷烃和糖类的污染特征及来源解析

Pollution Characteristics and Source Analysis of n-alkanes and Saccharides in PM_(2.5) During the Winter in Liaocheng City

为研究聊城市冬季大气PM_(2.5)中正构烷烃和糖类化合物的分子组成、浓度水平及来源,于2017年1～2月在聊城大学进行PM_(2.5)样品采集,对19种(C18～C36)正构烷烃和10种糖类化合物进行分析,并采用主成分分析法(PCA)解析其来源.结果表明,聊城市冬季PM_(2.5)中总正构烷烃的质量浓度为(456. 9±252. 5) ng·m^(-3),其中,灰霾期的质量浓度最高,约为清洁天的2倍,烟火Ⅰ期与Ⅱ期分别为清洁天的0. 9倍和1. 2倍.采样期间碳优势指数(CPI)值为1. 2±0. 1,植物蜡排放的正构烷烃对总正构烷烃的贡献率(%Wax Cn)为3. 1%～36. 0%,表明化石燃料燃烧是聊城市大气中正构烷烃的主要来源.聊城市冬季PM_(2.5)中糖类化合物的总质量浓度为(415. 5±213. 8) ng·m^(-3),其中左旋葡聚糖的浓度最高,其次是半乳聚糖和甘露聚糖,三者共占总糖的91. 6%,表明生物质燃烧源对聊城市大气气溶胶具有重要贡献.主成分分析(PCA)结果表明,聊城市冬季大气气溶胶中正构烷烃和糖类化合物主要来自化石燃料的燃烧和生物质燃烧.

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 nalkane 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.