Interannual Variation of Formaldehyde in a Typical Eastern Coastal City from 2014 to 2020

Using the Ozone Monitoring Instrument (OMI) derived satellite data (OMHCHO_003), Rizhao in Shandong Province was chosen as a typical eastern coastal city to investigate the characteristics of its vertical column density (VCD) changing trends for formaldehyde from 2014 to 2020. The spatial distribution of VCD for formaldehyde presents an obvious seasonal characteristic. The high value of VCD for formaldehyde in the summer is about 1.5 times the average value in other seasons. In summer, the high VCD value for formaldehyde is mainly located in Ju County, northwest of Rizhao. The VCD for formaldehyde in Rizhao has increased significantly over the last seven years. Moreover, its increasing rate in the Donggang District reached 0.20 \times 10¹⁵ mol cm⁻² a⁻¹, consistent with the North China Plain’s high anthropogenic emissions. The rising trend for formaldehyde correlates with the forest cover, the number of motor vehicles, and industrial energy consumption. The increasing trend in Rizhao is the largest among the chosen 32 coastal cities (covering Liaoning, Shandong, Jiangsu, Zhejiang, Fujian, and Guangdong coastal provinces). This study is an excellent application and reference for the deployment of formaldehyde prevention and control in Rizhao, and it fills the gap in the formaldehyde VCD study in coastal cities in eastern China.