Nitrate Enhanced Oxidation of SO2 on Mineral Dust: A Vital Role of Proton.
Nitrate Enhanced Oxidation of SO2 on Mineral Dust: A Vital Role of Proton.
复制标题
DOI：
10.1021/acs.est.9b01921
复制
发表时间：
2019-08
影响因子：
11.4
通讯作者：
Yue Zhang;Fengxia Bao;M. Li;Chuncheng Chen;Jincai Zhao
中科院分区：
文献类型：
--
作者：
Yue Zhang;Fengxia Bao;M. Li;Chuncheng Chen;Jincai Zhao
矿物粉尘上 SO2 的非均相氧化是大气中硫酸盐的重要来源。鉴于大部分硝酸盐沉积在矿物气溶胶上，因此迫切需要确定硝酸盐对矿物粉尘中 SO2 氧化的影响及其深入机制。在这项工作中，我们报告了对真实矿物粉尘的硝酸盐增强的 SO2 氧化。通过比较有或没有硝酸盐的亚利桑那州测试粉尘（ATD，矿物粉尘的典型代表）的 SO2 吸收行为，我们发现虽然硝酸盐阻碍了最初的 SO2 吸收，但在明显的诱导期后，它大大加速了 SO2 的吸收和氧化。换句话说，在含硝酸盐的 ATD (N-ATD) 颗粒上观察到了 SO2 吸收曲线中先阻碍后加速的特征。此外，HONO在加速期作为硝酸盐的还原产物被释放。诱导期SO2氧化产生的质子（H+）的积累对于加速SO2氧化起着关键作用。我们的工作表明，矿物粉尘上硝酸盐参与的 SO2 氧化可能是大气中硫酸盐来源的重要贡献之一。
Heterogeneous oxidation of SO2 on mineral dust is a significant source of sulfate in the atmosphere. Given that a large fraction of nitrate is deposited on the mineral aerosols, the determination of the effect of nitrate on the SO2 oxidation on mineral dust and its in-depth mechanism are much desired. In this work, we report nitrate-enhanced SO2 oxidation on authentic mineral dust. By comparing the SO2 uptake behaviors on Arizona test dust (ATD, a typical proxy of mineral dust) with or without nitrate, we found that although nitrate hinders the initial SO2 uptake, it substantially accelerates SO2 uptake and oxidation after a pronounced induction period. In other words, a hindering-then-accelerating feature in the SO2 uptake profile was observed on nitrate-containing ATD (N-ATD) particles. In addition, HONO was released in the accelerating period as the reduction product of nitrate. The accumulation of protons (H+) from SO2 oxidation during the induction period plays a key role in the acceleration of SO2 oxidation. Our work suggests that the nitrate-participating SO2 oxidation on mineral dust can be one of the important contributions of sulfate source in the atmosphere.