Meteorological parameters impact on spatio-temporal dynamics of VOCs after CNG implementation in transport sector in Delhi

Abstract

The present study comprises the measurement of total volatile organic compounds (TVOC) in ambient atmosphere of Delhi. The study has been carried out in three different ambient locations during winter and summer seasons of 2015. Real time monitoring was done for TVOC using a data-logging photo-ionization detector. The observed levels of TVOC were found to be higher during winter (ranged from 84.7 to 266.7 g/m) as compared to summer (ranged from 58.5 to 179.5 g/m) at all selected sites. The higher levels in winter could be due to low planetary boundary layer, calm condition and high atmospheric stability. These variations could be an account of factors such as distribution of emission sources around the sampling site and the prevailing meteorological conditions. It is clearly noticed that the levels of TVOC were found to be higher and lower during the morning and noon time. The higher levels of TVOC have been noticed during weekdays as compared to weekends at all the studied sites. It could be attributed to heavy traffic load, traffic flow and human activities during the weekdays. The association of TVOC with meteorological variables (ambient temperature and relative humidity) was also studied. Results showed that TVOC is positive weakly correlated with ambient temperature respectively during winter (R 2 =0.35) and summer (R 2 =0.10) seasons. On the other hand, relative humidity showed negative moderately strong correlation with observed levels of TVOC during winter (R 2 =0.66) and summer (R 2 =0.54).