大连地区夏季非甲烷烃(NMHC)特征及其来源解析

非甲烷烃(NMHC)是臭氧的重要前体物之一,对臭氧的生成起着决定性的作用.为研究大连地区大气中NMHC的特征和来源,利用在线NMHC监测仪测定大连地区2014年7月和8月的NMHC组成、日变化并计算该地区的臭氧生成潜势,利用PCA受体模型初步估算大连地区NMHC来源.结果表明,大连地区总NMHC年平均浓度(体积分数)分别为80.7×10-9±62×10-9,其中烷烃所占比例最高,占NMHC总浓度的64%,其次是烯烃19%,芳香烃16%,乙炔1%.正癸烷、乙烯、正辛烷是大连地区NMHC中浓度最高的3种物质,部分物种浓度呈现明显的日变化特征.臭氧生成潜势(OFP)结果显示,大连地区芳香烃对该地区OFP的贡献最大,乙烯、间-乙基甲苯和对-乙基甲苯是对该地区OFP贡献最大的物质.利用主成分分析VOCs物种,提取出6个因子,分别归纳为溶剂使用、液化石油气(LPG)、汽车尾气、植物排放、石化炼制加工和老化气团传输.

Characteristics and Source Analysis of Non-methane Hydrocarbons(NMHC)in Dalian

Non-methane hydrocarbon (NMHC) play a very important role in the formation of ozone. The concentrations, compositions, and diurnal variation of NMHC were measured in July and August of 2014 in Dalian City. Continuous samples were collected in Dalian and were analyzed via gas chromatography. The results show that the annual mean concentration of total NMHC (TNMHC) concentrations was 80.7×10^-9±62×10^-9. Alkanes were the most abundant components, accounting for 64% of the TNMHC, followed by alkenes, aromatics, and acetylene, which accounted for 19%, 16%, and 1%, respectively. n-Decane, ethene, and octane were the top three species in Dalian City, and the diurnal variation of NMHC in this area was obvious. The ozone formation potential (OFP) results show that the contribution of aromatics to the OFP in Dalian was the largest, and ethylene, m-ethyltoluene, and p-ethyltoluene were the most important contributors to the OFP in this area. Principal component analysis (PCA) was used to identify the sources of the VOCs. Six sources were resolved by the PCA:solvent usage, LPG, traffic sources, biogenic sources, petrochemical refining, and aged air transportation.