Profiling amino acids of atmospheric particulate matters collected in urban-rural complex areas, Korea

Winter PM10 (5 sites) and PM2.5 (3 sites) samples were collected in Jinju, Korea, to analyze mass concentration, composition (organic substances, ions, amino acids, amines), and correlations. The average PM10 and PM2.5 concentrations were 39 μg/m³ and 27 μg/m³, respectively, representing 39% and 76% of their respective 24-hour standards. Anions (SO₄²⁻, NO₃⁻, Cl⁻) dominated, with notable cation levels (NH4⁺, Na⁺, K⁺). Free Amino Acid (FAA) concentrations were 54.8 ng/m³ (PM10) and 52.7 ng/m³ (PM2.5), while Combined Amino Acid (CAA) levels were higher at 93.0 ng/m³ (PM10) and 85.0 ng/m³ (PM2.5). Hydrophobic amino acids (Ala, Val, Leu, Ile), primarily derived from soil, were predominant in FAA. While FAA showed no significant correlation with PM mass, CAA exhibited strong associations, suggesting secondary formation via photochemical reactions. Correlation analysis further indicated that soil-derived amino acids significantly contribute to FAA, emphasizing the influence of rural environments on particulate composition. These findings highlight the role of secondary pollutants like CAA in particulate matter formation, providing insights into organic aerosol sources in rural areas.