Tempo-spacial variation and source apportionment of atmospheric formaldehyde in the Pearl River Delta, China

Abstract

Formaldehyde (HCHO) plays an important role in atmospheric photochemistry and air quality. In this study, to investigate the sources and characteristics of formaldehyde pollution in different regions of southern China, formaldehyde online monitoring system and proton transfer reaction mass spectrometer were used to simultaneously monitor the level of HCHO and other non-methane hydrocarbons in the environment at urban site (HSTY) and rural site (NA) in the Pearl River Delta (PRD) of China. The results showed that formaldehyde concentrations were higher in autumn, with (4.46 ± 3.15 ppbv) and (2.13 ± 1.46 ppbv) for urban and rural sites, respectively, compared to (1.51 ± 0.80 ppbv) and (1.84 ± 0.93 ppbv) for winter. Continental air masses bring many secondary and biological species, with isoprene playing an important role in secondary HCHO generation. Using a photochemical age-based method to allocate HCHO, the highest proportion of secondary anthropogenic occurs at urban site (39.4%–42.5%), whereas biogenic contribute the most at rural site (39.1%–43.7%). Fewer human activities result in a lower proportion of primary anthropogenic at rural site (10.8%) compared to urban site (12.2%). These findings demonstrate the interplay between anthropogenic and biogenic sources, which would help understand the formation of photochemical pollution in the PRD.