[Evolution Characteristics of Atmospheric Formaldehyde Emissions in Guangdong Province from 2006 to 2020]

Atmospheric formaldehyde, a key precursor for ozone (O₃) and secondary PM_2.5, is carcinogenic and plays an important role in atmospheric photochemistry and the formation of secondary pollution. However, the lack of understanding of the emission sources of atmospheric formaldehyde limits the study on the formation mechanism of secondary pollution and the formulation of pollution control strategies. This study used the emission factor and source profile methods to establish the emission inventories of formaldehyde in Guangdong Province from 2006 to 2020 and identified the main emission sources of formaldehyde and spatial and temporal evolution characteristics. The results showed that the formaldehyde emissions in Guangdong Province fluctuated in the range of 39000-56000 tons during 2006 to 2020, exhibiting a very weak downward trend. Biomass combustion is an important source of formaldehyde emission in Guangdong Province, of which the contribution decreased from 58% in 2006 to 27% in 2020 owing to effective control measures implemented in Guangdong Province. The solvent use source became the predominant emission source of formaldehyde in 2020 by contributing up to 28%, primarily through plastic products and asphalt paving sources. The construction machinery and trucks fueled by diesel were important contributors of formaldehyde emissions from mobile sources. Although the formaldehyde emissions in the Pearl River Delta and the non-Pearl River Delta were equivalent, the spatial distributions showed that formaldehyde emission hotspots were concentrated in the center of the Pearl River Delta and the eastern and western areas of the non-Pearl River Delta. This was primarily because the solvent use and mobile sources were the main sources of formaldehyde emissions in the Pearl River Delta, whereas the biomass combustion source was the dominant source in the non-Pearl River Delta. Therefore, the formaldehyde emission mitigations of the industrial and mobile sources in the central region of the Pearl River Delta and the biomass combustion source in the western area of Guangdong should be further strengthened in the future.