Study of SO₂ and NO_X Distribution and Emission in Tangshan Based on Mobile DOAS Techniques

Sulfur dioxide (SO2) and nitrogen oxides (NOX) as important primary emissions in the atmosphere. Anthropogenic activities of SO2 and NO, excessive emissions will cause great harm to the ecological environment and human health, in 2018 the Ministry of Environmental Protection "Announcement on the implementation of special emission limits for air pollutants in cities in the Beijing-Tianjin-Hebei air pollution transmission corridor" on the "2+26" cities need to implement special emission limits for SO2, NO, and other air pollutants, so it is important to understand the distribution and emission of SO2 and NO, in these cities for air pollution prevention and control. As one of the heavy industrial cities with the most serious air pollution among the "2 + 26" cities, Tangshan City has implemented many air pollution prevention and control measures in recent years, but the air quality is still not optimistic. Therefore, in order to obtain the time and space distribution of the main pollutants in the urban area of Tangshan City, to quantitatively analyze the emissions of different regional sources, and to identify the sources of the main pollutants, a mobile pollution gas monitoring system based on mobile DOAS techniques was used from February 26 to March 1, 2021, to conduct aerial observation experiments for the urban area of Tangshan City and some industrial parks (steel, thermoelectric and coking enterprises) to obtain the Spatial distribution of NOx and SO2 along its course and the emission fluxes in the moving area. The experimental results show several areas with high NO2 values in the first ring of Tangshan City, all of which are located at interchanges and junctions where vehicles are concentrated. The NO2 and SO2 VCD obtained in the walkway of the industrial park are both higher, 1. 75 similar to 1. 99 times and 2. 21 similar to 3. 44 times higher than those of the first ring, respectively, and there are high NO2 and SO2 emissions from some enterprises in the industrial park. Combining the ratio of vertical column concentration SO2/NO2 and the ratio of near-ground concentration CO/NO2 and using the Pearson correlation coefficient to determine the correlation between SO2 and NO2 column concentration and NO2 near-ground concentration and column concentration, further analyzing the main pollution sources in different areas, the results show that the lowest SO2/NO2 obtained by the first ring walkway is 0. 42, CO/NO2. The highest correlation r between NO2 surface and column concentrations reached 0. 56. The highest SO2/NO2 and lowest CO/NO2 was 0. 81 and 7. 13 in the March 1 aerial walk in Fengnan Industrial Park, with a good correlation r between SO2 and NO2 VCD of 0. 787. The air pollutants in the first ring area of Tangshan City are mainly vehicular traffic exhaust emissions. The sources of air pollutants in the Fengnan Industrial Park are dominated by a large amount of NO2 and SO2 released from elevated point sources (chimneys) during industrial production.