Abstract
In this paper presents the assessment of source profile of nonmethane hydrocarbons (NMHCs) in the ambient air of Delhi. The samples were collected from five different urban sites using tedlar bags for aliphatic NMHCs and activated adsorption charcoal tubes for aromatic NMHCs during October 2014 to September 2015. Eleven aliphatic NMHCs propane, n-butane i-butene, i-butane, 1,3-butadiene, trans-2-butene, cis-2-pentene, n-pentane, n-hexane, heptane and four aromatic NMHCs benzene, toluene, o-xylene, p/m-xylene were identified in 112 urban ambient air samples. Samples were analysed using gas chromatography which is coupled with flame ionization detector (GC-FID). Pearson correlation coefficient (r) found to be = 0.5±0.2, shows significance level to have moderate among the NMHCs, indicates NMHCs in the urban ambient air have many sources profile mentioned in PCA result. Factor analysis(FA) and receptor model, i.e., Principal Component Analysis(PCA)/Absolute Principal Component Score (APCS) was used for identification of source profile distribution. PCA analysis after the varimax rotation have identified six possible source profile and explained about 70 % of the total dataset. The average % contribution of NMHCs emitted from vehicles was found to be 23%, whereas polymer manufacturing industries contributes 19% and from refinery operation/ gas station contribute 14%, and 13%, emitted from flare emissions and 10% from natural gas emissions. The secondary industrial process, including paints, body soaps and metal fabricator and processing was contributing 8%. Out of these remaining 13% was estimated as unidentified sources. These findings may be used by government authorities to formulate policies and strategies for improvement of urban air quality that can improve the health of urban communities.
Highlights
In the urban atmosphere non methane hydrocarbons (NMHCs) are most important groups of air pollutants[1]
We examined the concentration of selected NMHC and its source identification and percentage contribution using Principal Component Analysis (PCA)/Absolute Principal Component Score (APCS) receptor model in the metro city, Delhi, India
The ratio of B/T value confirmed that the vehicular source profile, was the main sources of NMHCs in urban air of Delhi
Summary
In the urban atmosphere non methane hydrocarbons (NMHCs) are most important groups of air pollutants[1] It is an important precursor of ground level ozone (O3)[2,6] and peroxy acyl nitrates (PAN) formation which can injurious to human health and vegetation[7,11]. Sanchez et al.,[34] used PCA/APCS receptor model and they identified natural gas emissions was the major contributors of NMHCs whereas flare emissions, refinery process, fugitive gasoline emissions, industrial processes, and vehicle exhausts were lesser contributer in the coastal urban ambient air of Texas, United State. Pandit et al.,[24] applied PCA receptor model on atmospheric NMHCs in Mumbai, India They found vehicular emission was the major source of NMHCs. In the context of ambient air of Delhi, no comprehensive study has been reported on the concentration measurement and source apportionment of NMHCs species. We examined the concentration of selected NMHC and its source identification and percentage contribution using PCA/APCS receptor model in the metro city, Delhi, India
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