Characteristics and origins of fine particulate amines at a coastal mountain site in northern China in spring

Abstract

Low-molecular-weight amines are the most abundant amine compounds in the atmosphere and they affect new particle formation, aerosol properties, climate change and human health. To understand the chemical composition, diurnal variation, influences of terrestrial and marine emissions, and potential sources of fine particulate amines in the coastal area in northern China, field sampling and measurements was conducted at coastal Mt. Lao in the spring of 2021. The total concentration of amines in PM2.5 was around 60 ng m−3 on average. Dimethylamine was the most abundant compound with mean fraction of 27.2% in the quantified 16 amines, followed by diethylamine (19.6%) and ethanolamine (12.6%). Elevated concentrations of amines usually appeared with high levels of CO, SO2, NOx, and/or moderately high humidity. Amines exhibited higher concentrations during the daytime than nighttime at the mountain site, due to more intense anthropogenic activities at daytime. The concentration peak in the late afternoon is ascribed to relatively strong anthropogenic emissions and enhanced gas-to-particle partitioning. Furthermore, comparison between terrestrial- and marine-airmass dominated samples shows that most amines primarily came from terrestrial activities, while TMA was mainly from marine sources. Source apportionment with the positive matrix factorization model identified seven major sources including agricultural emissions, industrial production, biomass burning, coal combustion, marine emissions, traffic emissions and crustal dusts. Notably, high contributions from agricultural source and biomass burning were observed at this coastal mountain site, indicating differential compositions and origins of particulate amines in different seasons and locations.