Wintertime source attribution and health risk assessment of particulate Nitro(so) compounds at urban and background sites in Republic of Korea

초록

Atmospheric nitrosamines and nitramines are carcinogenic organic nitrogen compounds that may originate from both primary emissions and secondary atmospheric reactions. This study investigated seven particulate nitrosamines and two nitramines in fine particulate matter (PM2.5) collected during February 2024 at two contrasting sites in Korea: Ansan (AS, urban-industrial) and Baengnyeong Island (BN, background). Contrary to expectations, total nitrosamine concentrations were higher at BN (4.26 f 2.21 ng/m3) than at AS (2.86 f 1.85 ng/m3), primarily driven by elevated NDBA levels associated with local combustion sources at BN. This pattern suggests that military activities at BN may contribute to local emissions, while AS showed lower concentrations despite being an industrial complex, possibly due to its focus on machinery and electronics manufacturing. During the intensive firework period, NDBA proportions increased at both sites, with larger increases at BN (from 34.11 f 18.27% to 44.60 f 24.32%) compared to AS (from 3.56 f 3.06% to 5.00 f 2.88%), coinciding with the timing of regional firework activities. Statistical analysis identified firework period impacts through elevated Ba and K at both sites. Box modeling of NDMA showed a moderate positive correlation between estimated and measured concentrations at BN (R = 0.44, p = 0.087) compared to AS (R = _ 0.13, p = 0.499), suggesting that secondary formation is one of several contributing factors to NDMA at the background site. Correlations improved when excluding the firework-period period, potentially indicating enhanced local formation processes. Cancer risk estimates were higher at AS (3.08 & times; 10_ 7to 2.65 & times; 10_6) than BN (1.92 & times; 10_ 7to 1.62 & times; 10_6), though both remained within acceptable ranges. While firework-period increased concentrations, health risks decreased at BN (p = 0.04) due to compositional shifts toward less toxic NDBA, whereas AS showed no significant change (p = 0.63).

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