Abstract:
From September 18
th-20
th, 2022, an ozone (O
3) pollution episode occurred in Fuzhou. The O
3 concentration from 11:00 to 14:00 remained above 160 μg/m³. On September 19
th, 2022, the daily maximum 8-hour average O
3 concentration reached 176 μg/m³. This episode may be related to the offshore O
3 transport caused by the northeastern airflow in the periphery of Typhoon ‘Nanmadol’ No.14. Here, based on the concentrations of conventional atmospheric pollutants and VOCs components and meteorological data from September 15
th to 21
st, 2022, combined with the Lagrange particle diffusion model (LPDM), regional air quality model (WRF-CMAQ), and observation-based chemical box model (OBM), we analyzed the process of this O
3 pollution episode, quantitatively assessed the contribution of maritime O
3 transport and the effect of emission reduction of O
3 precursors on O
3 pollution, which can provide support for the prevention and control of O
3 pollution in Fuzhou under the influence of typhoon systems. The main conclusions are as follows: (1) Based on the ∆O
x (hourly concentration change of photochemistry oxidant) results, under the influence of the northeast wind, the air mass with high O
3 concentrations from the offshore was transmitted to the inland of Fuzhou on 19
th. The contribution of O
3 transmission was about 5-17 μg/m
3. From 18:00 to 23:00 on the 19
th, the hourly transportation contribution to the Jiulong site reached 6.0 μg/(m
3·h). (2) From September 18
th to 20
th, ozone generation in Fuzhou City gradually shifted from the VOCs and NO
x synergistic control area to the VOCs control area. The emission reductions of VOCs and NO
x in Fuzhou should be controlled at a ratio of 1∶1 in the early stage of typhoon influence. In the later stage, the emission reduction of VOCs should be increased, and the ratio should be adjusted to 2∶1 to mitigate the impact of uncontrollable factors such as high temperatures and the increased biogenic VOCs emissions on the O
3 pollution in pollution days. The study found that better control can be achieved through scientific and dynamic adjustment of NO
x and VOCs emission control.