摘要：The present study reports on the abundance of reactive nitrogen (NH3 and NO2) at two sites, i.e. Okhla (urban site) in Delhi and Mai (rural site), located in the nearby state: Uttar Pradesh. The measurements were carried out during the period from October, 2012 to September, 2013 on a monthly basis. The average concentrations of NH3 at Okhla and Mai have been recorded as 40.4 ± 16.8 and 51.57 ± 22.8 μg m−3, respectively. The average concentrations of NO2 have been recorded as 24.4 ± 13.5 and 18.8 ± 12.6 μg m−3 at Okhla and Mai, respectively. Results show that the seasonal variation at Mai was more prominent where NH3 concentrations varied at 72.0 μg m−3 during the winter, 47.2 μg m−3 during the summer and 30.7 μg m−3 during the monsoon season, whereas at Okhla the average NH3 concentrations were almost equal during different seasons, namely 44.2 μg m−3 during the winter, 42.5 μg m−3 during the summer and 38.9 μg m−3 during the monsoon season. This is probably due to significant differences in crops and in the fertilizer amounts applied across the seasons in rural areas, while urban areas have almost constant sources throughout the year. Winter concentrations were highest at both sites, followed by summer and then the monsoon season. The average NO2 concentrations were recorded as 39.6 μg m−3, 24.5 μg m−3and 10.4 μg m−3 during the winter, summer and monsoon season at Okhla, whereas the average NO2 concentrations were recorded as 27.5 μg m−3, 17.2 μg m−3 and 4.1 μg m−3 during the winter, summer and monsoon season, respectively. NO2 emissions at Okhla may be attributed to various urban activities, such as vehicular traffic and industries, while NO2 emissions at Mai may be attributed to biomass burning as a major source. However, NO2 concentrations from vehicular traffic and nearby industries cannot be ignored at Mai.
