Variation of trace gases in Kannur Town, a coastal South Indian city

Abstract

This paper describes diurnal and seasonal variations of trace air pollutants include surface ozone (O3), oxides of nitrogen (NOx), carbon monoxide (CO), volatile organic compounds (Benzene, Toluene, Ethyl Benzene, Xylenes which are classified as BTEX)), ammonia (NH3), sulphur dioxide (SO2), and meteorological parameters observed at Kannur town (11.87° N, 75.37° E, 2 m msl) for a period of one year from September 2019. Seasonal variations of trace air pollutants exhibit a daytime maximum during winter due to the enhanced local emission and long-range transport, and minimum during the monsoon period. Surprisingly, air pollutants except O3 show a reduction in concentration in the months of April 2020 due to countrywide lockdown in the wake of restricting the spread of COVID 19. Weekday/weekend variations of air pollutants reveal that high concentrations of O3 are found on weekends compared to weekdays, unlike the concentrations of all other pollutants are found low during weekends. From the analysis of the chemical coupling between NO, NO2, NOx, O3, and OX (=O3+NO2), it is found that OX has both regional and local contributions on NOx. Intercorrelations between trace pollutants showed a strong positive correlation between O3 and CO, a negative correlation between O3 and NOx.

Keywords

• Air pollution
• Trace pollutants
• Ozone
• Boundary layer height
• Kannur