A new advance in the pollution profile, transformation process, and contribution to aerosol formation and aging of atmospheric amines

Amines, formed with the replacement of hydrogen atoms by NH3 molecules of volatile organic compounds, possess distinctive properties of alkalinity, volatility, water-solubility and oxidability and have attracted more and more attention due to their significant contributions to atmospheric pollution during the past few decades. To understand the environmental behaviors of amines in the atmospheric pollution process, this review mainly summarizes a new advance in sources and sinks of amines and their effects on atmospheric particulate matter (PM) formation and climate evolution within the last decade. First, the pollution profiles and source identification of amines are summarized. Some newfound sources of amines are correspondingly updated. Meanwhile, the current monitoring methods of amines are also evaluated. Second, the atmospheric oxidation reaction mechanisms of amines with various active radicals are discussed. Third, the combined data of field monitoring, laboratory experiments and theoretical calculations verified that amines contribute significantly to aerosol particles, including oxidation product condensation, direct dissolution, acid-base reactions and replacement reactions. Besides, we discussed how amines affect the climate directly or indirectly by generating brown carbon in PM, enhancing hygroscopicity and activating cloud condensation nuclei. All in all, the review provides new insights into the overall atmospheric circulation and final fate of amines as well as their effects on atmospheric aerosol particle formation and the climate.