上海市亚微米颗粒物中有机胺的浓度与组成特征

Concentration and Composition of Organic Amines in PM1 in Shanghai

有机胺是大气细颗粒中一类重要的碱性含氮有机物,可能在大气新粒子生成和二次有机气溶胶形成过程中起着重要作用,但我们对大气细颗粒物中有机胺浓度和组成的了解还很缺乏。为了解上海市亚微米颗粒物(PM_(1))中有机胺的浓度、组成及潜在来源,在上海大学宝山校区于2017年6月—2018年5月采集了65个PM_(1)样品,采用苯磺酰氯(BSC)衍生化和气相色谱-质谱联用仪(GC-MS)检测方法定量分析了甲胺(MA)、二甲胺(DMA)、乙胺(EA)、二乙胺(DEA)、丙胺(PA)和丁胺(BA)6种低分子脂肪胺的浓度,并通过相关性分析、主成分分析及气团后向轨迹分析探讨了有机胺的潜在来源。结果表明,采样期间上海PM_(1)中6种有机胺总质量浓度为4.60—132.98 ng·m^(-3),年平均质量浓度为46.49 ng·m^(-3);甲胺、二甲胺、乙胺和二乙胺是主要的有机胺单体,占6种有机胺总浓度的97%,其中甲胺的年均占比为51.3%。PM_(1)中有机胺总浓度呈现较明显的季节性变化:夏季>秋季>春季≈冬季;MA在有机胺总浓度中的占比夏季最高、冬季最低,而DMA和DEA的相对贡献冬季最高、夏天最低。有机胺总浓度与SO_(4)^(2-)浓度之间在不同季节均存在显著正相关关系,而与NO_(3)^(-)之间仅在冬季和夏季显著相关,说明有机胺可能主要与硫酸根结合。有机胺单体之间的相关性分析以及结合主要水溶性组分的主成分分析表明这些有机胺单体可能来自相似的排放源,但不同单体浓度的季节变化不同,说明不同季节有机胺的来源有一定的差别,二次生成及生物质燃烧可能不是上海PM_(1)中有机胺的主要来源。后向轨迹聚类分析显示,有机胺主要受本地排放源的影响,外来传输以及海洋源可能有一定的影响,但不是主要的来源。研究结果能为大气细颗粒物环境影响评价提供重要的基础数据。

Organic amines are an important group of alkaline nitrogen-containing compounds in the atmospheric fine particles,which may play an important role in the formation of new particles and secondary organic aerosols.However,data on the concentration and composition of organic amines in the atmospheric fine particles is still very limited.In order to understand the compositional characteristics and potential sources of organic amines in the sub-micron particles(PM_(1))in Shanghai,65 PM_(1) samples were collected at the Baoshan campus of Shanghai University from June 2017 to May 2018.Six low molecular weight aliphatic amines including methylamine(MA),dimethylamine(DMA),ethylamine(EA),diethylamine(DEA),propylamine(PA)and butylamine(BA)were measured using a gas chromatography-mass spectrometer(GC-MS)after derivatization with benzenesulfonyl chloride(BSC).Correlation analysis,principal component analysis(PCA)and air parcel backward trajectory analysis were used to investigate the potential sources of amines.Results showed that the total concentration of six organic amines(Ʃamines)in PM_(1) in Shanghai was 4.60-132.98 ng·m^(-3),with an annual average of 46.49 ng·m^(-3).Methylamine,dimethylamine,ethylamine and diethylamine were the main individual amines,accounting for 97%of theƩamines annually,among which methylamine alone accounted for 51%.The concentration ofƩamines showed a distinct seasonal trend of summer>autumn>spring≈winter.The contribution of MA toƩamines was the highest in summer and the lowest in winter,whereas for DMA and DEA it was the highest in winter and the lowest in summer.Significant correlations were found in all seasons betweenƩamines and sulfate,but the significant correlation betweenƩamines and nitrate was only found in winter and summer,suggesting that amines might mainly combine with sulfate.The correlation analysis between the individual amines combined with the PCA analysis of amines and the main water-soluble components showed that different individual amines might come from similar emission sources,but the emission sources of amines in different seasons would be different to some extent,and secondary formation and biomass burning might not be the main sources of amines in PM_(1) in Shanghai.Cluster analysis of the backward trajectories of air parcels arriving in Shanghai showed that the concentration of the organic amines in PM_(1) in Shanghai was mainly affected by local emissions,and long distance transport and marine emissions were not the main sources.The results could provide important data for the environmental impact assessment of the atmospheric fine particles.