摘要
2011年9月1日～11月21日在上海市城区对大气中颗粒物质量浓度和挥发性有机物体积分数进行了在线连续观测.期间共出现4次大气污染过程:PD1(9月20～23日)、PD2(10月5～9日)、PD3(10月13～18日)、PD4(11月10～14日).本测点大气PM2.5的平均浓度分别为(45±16)、(76±46)、(57±36)和(122±92)μg·m-3,VOCs的体积分数分别为(30.87±30.77)×10-9、(32.09±30.69)×10-9、(34.04±28.13)×10-9和(44.27±31.58)×10-9;烷烃、烯烃、芳香烃的体积分数分别占TVOC的53.58%、27.89%、10.96%;用OH消耗速率(LOH)和臭氧生成潜势(OFP)评估了VOCs大气化学反应活性.结果表明,烯烃和芳香烃是本测点秋季大气VOCs中对LOH和OFP贡献最大的关键活性组分.利用气溶胶生成系数FAC和OC/EC比值法估算上海市SOA的生成潜势,两种方法得出的SOA浓度值分别为1.43μg·m-3和4.54μg·m-3,比值法明显较高,这主要是本研究测得的SOA前体物偏少所致.其中芳香烃不仅是OFP的关键活性组分,而且也是SOA的重要前体物.应用PMF模型对VOCs进行源解析,确定了秋季上海市大气中VOCs的6个主要的污染来源,分别为汽车尾气(24.30%)、不完全燃烧(17.39%)、燃料挥发(16.01%)、LPG/NG泄露(15.21%)、石油化工(14.00%)、涂料/溶剂的使用(13.09%).汽车尾气和涂料/溶剂等源排放的VOCs中富含OFP关键活性组分和SOA重要前体物,它们对VOCs浓度的贡献占TVOC的37.39%,这些排放源应列入未来上海市大气复合污染控制的优先范围.
A continuous measurement was conducted in urban area of Shanghai from 1st September to 21st November, 2011. The mass concentration of PM2.5 and the mixing ratio of VOCs were obtained during the period. Four pollution episodes were observed： PD1 （20th-23rd September）, PD2 （5th-9th October）, PD3 （13rd- 18th October）, PD4 （10th- 14th November）. The average mass concentrations of PM25 were （45± 16） , （76 ± 46） , （57 -±36） and （122± 92） μg.m-3, respectively. The mixing ratio of VOCs were （30.87±30.77）×10^-9, （32.09±30.69）×10^-9, （34.04±28.13）×10^-9 and （44.27±31.58）×10^-9. Alkane, alkene and aromatic hydrocarbons accounted for 53.58% , 27.89% , and 10. 96% of the total VOCs, respectively. The OH radical loss rate （L^OH） and the ozone formation potential （OFP） were applied to assess the chemical reactivity of VOCs, the results showed that the alkenes and aromatics were the most important contributors to L^OH Sand OFP in the atmosphere in the urban area of Shanghai, in autumn. Fractional aerosol coefficients （FAC） and the ratio of organic carbon to element carbon （OC/EC） were used to estimate the potential formation of secondary organic aerosols （SOA） in Shanghai, the SOA concentration values obtained by the two methods were 1.43 μg.m^-3 and 4.54 μg.m^-3, respectively. The value predicted by OC/EC was significantly higher, which was mainly due to the low amount of SOA precursors measured in this study. The aromatics were not only the most important contributors to OFP, but also important SOA precursors. By applying the positive matrix factorization （PMF） model, six major sources were extracted to identify the sources of VOCs in autumn in Shanghai, including vehicle exhaust （24. 30% ） , incomplete combustion （ 17.39% ） , fuel evaporation （ 16.01% ）, LPG/NG leakage （15. 21% ） , petrochemical industry （14.00%）, and paint/solvent usage （13.09% ）. Vehicle exhaustand paint/solvent usage contain abundant aromatics species which are the most important contributors to OFP and important SOA precursors. The above two sources contributed 37.39% of the total VOCs concentration. Hence, these sources should be listed as priority of air pollution control strategy for Shanghai in future.
出处
《环境科学》
EI
CAS
CSCD
北大核心
2013年第2期424-433,共10页
Environmental Science
基金
环境保护公益性行业科研专项(201009001)
环境模拟与污染控制国家重点联合实验室专项经费项目(11K05ESPCP)
上海市科委项目(11231200500)
浙江省重大科技专项重点社会发展项目(2011C13022)
关键词
挥发性有机物
二次有机气溶胶
有机碳与元素碳
二次有机碳
来源解析
volatile organic compound （VOC）
secondary organic compound （SOA）
organic carbon （OC） and element carbon（EC）
secondary organic carbon （SOC）
source apportionment
