Characterization of Particulate Nitrosamines and Nitramines at Industrial and Background Sites in Korea: Field Observations and Laboratory Experiments

Particulate N-nitrosamines and nitramines are potent organic carcinogens with significant public health implications. They are formed in the atmosphere through primary emissions from sources such as rubber and plastic combustion, and tobacco smoke, as well as secondary formation of gaseous and aqueous phase amine. This study quantifies seven nitrosamines and two nitramines in PM_2.5 collected from summer 2024 to spring 2025 at Ansan (industrial) and Baengnyeong Island (background). The mean total concentration at Ansan (2.67 ± 1.87 ng m^-3) was comparable at Baengnyeong (2.23 ± 1.45 ng m^-3). Among the quantified species, N-nitrosodi-n-butylamine (NDBA) was generally the most abundant at both sites across most seasons. At Ansan, NDBA showed positive correlations with elemental carbon (EC) during autumn (r = 0.517, p < 0.01) and with SO₂ during summer (r = 0.488, p < 0.01); however, these correlations alone could not resolve the relative contributions of primary emissions versus secondary formation.

To better understand the role of aqueous-phase chemistry in NDBA formation, we conducted controlled batch reactor experiments simulating atmospheric aqueous aerosol reactions. The experiments systematically varied precursor (dibutylamine and nitrite) concentrations, pH, temperature, and reaction time to quantify NDBA formation rates in the homogeneous aqueous phase. Experimental results were integrated with field-based observations to investigate possible connections between environmental conditions such as pH levels and precursor availability and observed variations in ambient NDBA concentrations across different sites and seasons.