Research on horizontal distribution of NO2 around Coal-Fired power plants based on two-dimensional Multi-Axis Differential Optical Absorption Spectroscopy (MAX-DOAS)
摘要
The debate over whether mobile or stationary sources are the primary contributors to urban air pollution persists. To accurately assess the specific impact of a coal-fired power plant in Hefei on local air quality, this study was conducted on Hefei Science Island from January to February 2025. Utilising two-dimensional multi-axis differential absorption spectroscopy (2D-MAX-DOAS), the horizontal distribution of NO2 was observed. The technique was used to measure the differential slant column densities (dSCDs) of NO2 and O4 in eight azimuthal directions within ultraviolet spectral window, thereby establishing a spatial distribution data foundation for source apportionment. Based on observational data, the vertical distribution of NO2 within the atmosphere and the height of the mixing layer were inverted. Considering the exponential distribution characteristic of NO2 in the inversion results, a correction factor was proposed to adjust the volume mixing ratio of NO2. Multiplying this corrected value by the mixing layer height yielded the vertical column density of NO2. Comparisons were made between the mixing layer height and lidar observations, as well as between the vertical column density of NO2 and TROPOMI satellite data. The results demonstrated high consistency, thereby further validating the reliability of the horizontal NO2 concentration data. The study indicates that NO2 concentrations near a power plant in Hefei remain around 20 µg/m3, suggesting a limited contribution to local NO2 pollution and not constituting a primary source.