Non-negligible emissions of amines from vehicle and ship exhausts in China

Amines have significant impacts on air quality, regional climate, and human health. To date, the emissions of amines from traffic sources remain unclear. In this study, we collected fine particulate matters from vehicle and ship exhausts, and subsequently characterized the emissions of 17 amines using ultra-performance liquid chromatography-mass spectrometry. The concentrations and composition of particulate amines vary depending on the types of vehicles and ships. Trimethylamine and 2-Amino-1-butanol were predominant in vehicle exhausts, whereas dimethylamine and diethylamine were prominent in ship exhausts. Diesel vehicles exhibited the highest levels of total amines, followed by gasoline vehicles and compressed natural gas vehicles. Small ships emitted significantly more amines than large ones, with amine concentrations decreasing as engine power increased. Amines emissions from vehicles and ship's exhausts were hypothesized to originate primarily from the three-way-catalyst, selective catalytic reduction, or exhaust gas recirculation systems in the presence of ammonia and organic compounds. Based on the determined emission factors, the annual emissions of fine particulate amines from vehicles and ships in China were approximately 312 kg and 534 kg, respectively. According to the gas particle partitioning coefficient from field measurements, the annual emissions of gaseous amines from vehicles and ships in China were estimated to be 4.2–12.0 Mg and 7.2–20.5 Mg, respectively. Overall, this study presents the unique emission characteristics of particulate amines from vehicle and ship exhausts and confirms the non-negligible emissions from traffic sources.