Variations of atmospheric SO2 and NO2 pollution in Yangtze River Delta of China

Ambient air quality is primarily affected by respirable particulate matter (PM), SO₂ and NO₂ concentrations in the atmosphere. Monthly remote sensing data of SCIAMACHY tropospheric SO₂ vertical column densities was measured from January 2004 to December 2010. OMI tropospheric SO₂ vertical column densities was measured from October 2004 to December 2010. And daily ambient air pollution index (API) data of SO₂ and NO₂ of Shanghai was obtained from January 2004 to December 2010. The spatial and temporal variations of SO₂ and NO₂ pollution in Yangtze River Delta region was analyzed through time series and linear regression methods to present the pollution actuality and to assess the effects of air quality measures implemented for Shanghai World Expo. In addition, ground-based monitoring API data was processed to validate satellite observations of tropospheric SO₂ and NO₂ vertical column densities. The results showed that: (1)there was a significant correlation between SO₂ concentration and NO₂ concentration; (2)there existed a downward trend of SO₂ and NO₂ concentrations in Yangtze River Delta; (3)ground monitored SO₂ and NO₂ concentrations were significantly lower during the Expo than the same time in past six years and (4)the ground observations revealed further that the drop extent of SO₂ concentration during the Expo in Shanghai was much larger than NO₂.