A long-term study of oxides of nitrogen, sulphur dioxide, and ammonia for a port and Harbor region in India

A long-term study of oxides of nitrogen (NOx), sulphur dioxide (SO2), and ammonia (NH3) has been performed in a port and harbor region in India from January 1997 to December 2000. Meteorological data was also collected to establish the correlation with gaseous pollutants concentrations. Monthly mean concentrations of NOx were in the range of 19.5-59.0 mug/m(3) and were observed to be highest during winter season. Monthly mean concentrations of SO2 were in the range of 8.6-51.3 mug/m(3) and were observed to be highest during winter season. The concentrations Of SO2 increased gradually from 18.8 mug/m(3) in 1997 to 33.3 mug/m(3) in 2000. This may be attributed to the increase in port activities and ship traffic, which had an annual growth of about 15%. Monthly mean concentrations of NH3 were in the range,of 87.1-235.1 mug/m(3) and the maximum concentration was observed during post-monsoon season. It may be concluded that NOx and SO2 have their maximum, values during winter season while NH3 has a maximum value during post-monsoon season. Statistical analysis was carried out for air pollutant data for the period 1997-2000 and correlation between gaseous pollutants (NOx, SO2, NH3) and meteorological parameters (temperature and wind speed) was estimated. NH3 was found to be weakly correlated with NOx (0.46), strongly correlated with SO2 (0.75) and negatively correlated with wind speed (-0.60). The highest correlation (0.87) was observed between SO2 and NOx because of common sources. A strong negative correlation was found between wind speed and gaseous pollutants. The above finding is also supported by monitoring results that when the wind velocity doubled, the concentrations of pollutants decreased sharply to about a half. Regression, analysis showed that relation-ship among NOx, SO2, wind speed, and temperature was moderate to strong while that among NH3, wind speed, and temperature was poor. Hence regression equations could be developed for predicting NOx and SO2 concentrations.