Characteristics of volatile organic compounds (VOCs) at an urban site of Delhi, India: Diurnal and seasonal variation, sources apportionment

Abstract

This study reports the measurements of 25 volatile organic carbon compounds (VOCs) in the ambient air at an urban location of Delhi, India. The air samples were collected in stainless steel canisters following the standard recommended practice of Environmental Protection Agency (EPA) and analysing using a gas chromatograph with Flame Ionization Detector (GC-FID) from January 2018 to June 2019. The most abundant are alkene (39%) followed by Alkane (36%), and aromatic (16%). Alkyne (9%) is observed in a very limited number of samples. Alkanes and aromatic compounds show a gradual decrease in concentration from morning to evening, whereas, the concentration of alkenes increased from morning to day time. Higher mixing height (m) during the day (0800–1800 h) and emissions from several sources have controlled the diurnal variation. VOCs show a strong seasonal cycle for alkanes (24–47%), alkenes (31–46%), Alkynes (4–18%), and aromatic compounds (14–20%). PCA/APCS-MLR analysis has been resolved 6 factors with 18 VOCs which are mostly dominated by gasoline evaporation (27.1%) and biomass burning (26.7%) followed by LPG (16.7%), and vehicular emissions (16.4%). PMF analysis shows gasoline vehicular emission + gasoline emission+ organic solvent (39.9%) followed by biomass burning (20.7%), LPG (15.8%), diesel vehicular emission (13.4%), and painting (10.1%).