Rapid sulfuric acid-dimethylamine nucleation enhanced by nitric acid in polluted regions.

Liu, Ling; Yu, Fangqun; Du, Lin; Yang, Zhi; Francisco, Joseph S; Zhang, Xiuhui · Proc Natl Acad Sci U S A · 2021

basic_science · Level V

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Abstract

Recent research [Wang <i>et al.</i>, <i>Nature</i> 581, 184-189 (2020)] indicates nitric acid (NA) can participate in sulfuric acid (SA)-ammonia (NH<sub>3</sub>) nucleation in the clean and cold upper free troposphere, whereas NA exhibits no obvious effects at the boundary layer with relatively high temperatures. Herein, considering that an SA-dimethylamine (DMA) nucleation mechanism was detected in megacities [Yao <i>et al.</i>, <i>Science</i> 361, 278-281 (2018)], the roles of NA in SA-DMA nucleation are investigated. Different from SA-NH<sub>3</sub> nucleation, we found that NA can enhance SA-DMA-based particle formation rates in the polluted atmospheric boundary layer, such as Beijing in winter, with the enhancement up to 80-fold. Moreover, we found that NA can promote the number concentrations of nucleation clusters (up to 27-fold) and contribute 76% of cluster formation pathways at 280 K. The enhancements on particle formation by NA are critical for particulate pollution in the polluted boundary layer with relatively high NA and DMA concentrations.

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