Department of Environmental Engineering, Kangwon National University, Chuncheon, 24341, South Korea.
Department of Chemical Engineering and Materials Science, Ewha Womans University, Seoul, 03760, South Korea.
Chemosphere. 2024 Feb;349:140794. doi: 10.1016/j.chemosphere.2023.140794. Epub 2023 Nov 25.
The contribution of ozonation to the formation of particulate nitrosodi-methylamine (NDMA) in the aqueous aerosol phase was investigated using measurement data from 2018 in Seoul, Republic of Korea and a box model. The correlation between the NDMA concentration and aerosol liquid water content and box model results showed that aqueous aerosol phase reactions, including nitrosation and ozonation, might contribute to the formation of NDMA. The concentration of NDMA and the ratio of O/dimethylamine exhibited a negative correlation, suggesting that the contribution of ozonation to NDMA formation may not be significant. Furthermore, when the daily concentration of NDMA exceeded 10 ng/m, the pH was 3.96 ± 0.48, indicating that the impact of ozonation on NDMA concentration might not be significant. To quantitatively investigate the contribution of ozonation, the ozonation mechanism that forms NDMA was included in the box model developed in our previous study. The model results showed that the ozonation contributed to the ambient concentration of NDMA (7.9 ± 3.8% (winter); 1.9 ± 3.0% (spring); 10.0 ± 0.77% (summer); 3.6 ± 7.3% (autumn)). It is estimated that the relatively higher O/NO ratio in summer (1.63 ± 0.69; 0.64 ± 0.52 (winter); 1.14 ± 0.92 (spring); 0.52 ± 0.54 (autumn)) could enhance ozonation and that relatively lower pH in summer (2.2 ± 0.4; 5.3 ± 1.2 (winter); 3.9 ± 1.2 (spring); 3.9 ± 0.7 (autumn)) could hinder nitrosation compared to that in other seasons.
采用 2018 年韩国首尔的测量数据和箱式模型研究了臭氧化对水相气溶胶中亚硝二甲胺（NDMA）形成的贡献。NDMA 浓度与气溶胶液水含量的相关性以及箱式模型的结果表明，水相气溶胶反应（包括亚硝化和臭氧化）可能有助于 NDMA 的形成。NDMA 浓度与 O/二甲胺的比值呈负相关，表明臭氧化对 NDMA 形成的贡献可能不显著。此外，当 NDMA 的日浓度超过 10ng/m 时，pH 值为 3.96±0.48，表明臭氧化对 NDMA 浓度的影响可能不显著。为了定量研究臭氧化的贡献，将形成 NDMA 的臭氧化机制纳入了我们之前研究中开发的箱式模型。模型结果表明，臭氧化对环境中 NDMA 的浓度有一定贡献（冬季为 7.9±3.8%；春季为 1.9±3.0%；夏季为 10.0±0.77%；秋季为 3.6±7.3%）。据估计，夏季相对较高的 O/NO 比值（1.63±0.69；0.64±0.52（冬季）；1.14±0.92（春季）；0.52±0.54（秋季））可能增强了臭氧化作用，而夏季相对较低的 pH 值（2.2±0.4；5.3±1.2（冬季）；3.9±1.2（春季）；3.9±0.7（秋季））可能比其他季节更不利于亚硝化作用。
