南阳市冬春交替期大气VOCs污染特征及来源解析

近年来我国中部地区臭氧污染问题日益凸显,而挥发性有机物(VOCs)作为近地面臭氧生成的关键前体物,有关其来源研究相较于我国东部地区相对欠缺.为了解我国中部地区VOCs污染特征及其来源,本研究于2017年2—3月在豫鄂陕三省交界处的河南省南阳市南阳理工学院站点开展了为期1个月的VOCs在线监测.测量结果显示,观测期间总VOCs平均浓度为(37.4±18.5)×10~(-9).与国内外已有研究的VOCs测量结果相比,本研究中烷烃、烯烃和炔烃的浓度处于中等偏上水平,而芳香烃浓度则较低.烯烃对臭氧潜势的贡献最高(37%),其次是芳香烃(28%).乙烯、二甲苯、甲苯、丙烯和C4~C5烷烃是最重要的活性组分.利用正交矩阵因子分析(PMF)解析出4个因子,分别是天然气/液化石油气使用+背景、交通排放、溶剂涂料使用和燃煤+生物质燃烧.观测期间南阳理工学院站点对VOCs浓度贡献最高的是燃煤+生物质燃烧因子,平均贡献率为35%,其次是交通排放因子(25%)、天然气/LPG使用+背景(23%)和溶剂涂料使用(17%).研究结果对于认识我国中部地区VOCs来源结构,进而开展VOCs和臭氧防治具有重要意义.

Characteristics and source apportionment of ambient VOCs during alternating period between winter and spring in Nanyang City, Henan Province

Ground-level ozone (O₃) pollution in middle areas of China has received much concern during recent years. Volatile organic compounds (VOCs) play important roles in photochemical production of ozone. In order to understand characteristics and sources of ambient VOCs in middle areas, one-month online VOCs measurements were conducted at Nanyang Institute of Technology (NIT) site in Nangyang City, Henan Province during February-March, 2017. The mean value of mixing ratios for measured VOCs was (37.4±18.5)×10^-9. Alkenes and aromatics were the two largest contributors to ozone formation potential (OFP), with relative contributions of 37% and 28%, respectively. Ethylene, xylenes, toluene, propene, and C4~C5 alkanes were the most important VOCs species to OFP. The positive matrix factorization (PMF) model was used to investigate VOCs sources in Nanyang and four factors were resolved, including usage of natural gas and liquefied petroleum gas (LPG) + background, traffic-related emission, usage of paints and solvents, combustion of coal and biomass. The factor combustion of coal and biomass is the largest contributor to ambient VOCs, with relative contribution of 35%, followed by traffic-related emission (25%), usage of natural gas and LPG+ background (23%), and usage of paints and solvents (17%). These results from this study will be useful to understand VOCs sources in mid-areas of China, and further provide basic data and useful information to formulate strategy for VOCs and O₃ control.