Global Modeling of Atmospheric Amines: Sources and Sinks

Abstract

Atmospheric amines (methylamine, MMA; dimethylamine, DMA; and trimethylamine, TMA) are critical to new particle formation, air quality, and climate, yet an integrated global cycling framework remains absent. This study develops a global emission inventory that integrates six source categories spanning anthropogenic sources (agriculture, chemical industry, transportation, residential, other industry, and biomass burning) and marine biological processes. We established a full atmospheric amine cycling framework within the Community Earth System Model by implementing four key sink mechanisms. Our estimated global annual emissions are 42.2, 26.9, and 394.9 GgN year ⁻¹ for MMA, DMA, and TMA, respectively. Agricultural activities dominate MMA (54%) and DMA (79%) emissions, while marine sources account for a remarkable 98% of TMA globally. Model simulations indicate short atmospheric lifetimes of three amines (3.34–4.94 hr), primarily controlled by gas‐phase oxidation (51.1%), followed by deposition (32.4%) and aerosol uptake (16.5%) on average across the three species. Global hotspots for MMA and DMA are concentrated in East Asia, Europe, and North America, while TMA peaks over the oceans. The burdens of amines in the Northern Hemisphere are 15%–25% higher than in the Southern Hemisphere. Comparison with 27 global observations validates the improved TMA simulation over marine regions, confirming the importance of the ocean source parameterization. Despite these advances, the systematic underestimation of atmospheric concentrations (NMB: −73% to −93%) indicates that source‐specific emission factors remain poorly constrained and that secondary formation mechanisms are incompletely represented in current global frameworks. This work provides an essential scientific foundation for incorporating amine cycles into Earth system models.