Abstract:

Historic and recent observational data of SO2 and NOx from Lin’an and Longfengshan background stations, located in the Yangtze Delta and the Northeast Plain region, respectively, are analyzed in order to study the differences in concentrations of these climate relevant acidic gases between the two regions and impacts of anthropogenic emissions on the gases since about one decade ago. The past and more recent levels of the gases are compared between the two sites, long-term trends of the gases at both sites are estimated, and the NOx/SO2 ratios for the two stations are obtained using the correlation method. The results show that in the middle 1990s the levels of SO2 and NOx were already considerably high at the background site of the Yangtze Delta region and since that time the anthropogenic emissions have only caused a significant increase in NOx concentration, making NOx another major pollutant in addition to SO2. Data from Longfengshan station suggest that the levels of acidic gases in the Northeast Plain region were very low in the past, and are still not high at present. However, the levels of these acidic gases in this less polluted region have been increasing at very high rates, therefore, the future levels of these gases in the region are not optimistic.

Key words: climate-relevant acidic gases, sulfur dioxide, nitrogen oxides, anthropogenic emission, Yangtze Delta, Northeast Plain