Kim Kitae, Kim Bomi, Ahn Yong-Yoon, Tran Khen Duy, My Truong Hanh Thi, Kim Jungwon
Korea Polar Research Institute (KOPRI), Incheon 21990, Republic of Korea.
Department of Polar Sciences, University of Science and Technology (UST), Incheon 21990, Republic of Korea.
J Phys Chem A. 2023 Mar 30;127(12):2830-2838. doi: 10.1021/acs.jpca.3c00482. Epub 2023 Mar 15.
The abiotic mechanism of molecular iodine (I) production from iodate (IO) remains largely unknown. Here, we demonstrate the production of I in the presence of IO and organic compounds in ice. When the solution containing IO (100 μM) and furfuryl alcohol (100 μM) at pH 3.0 was frozen at -20 °C, 13.1 μM of I was produced with complete degradation of furfuryl alcohol after 20 min. However, there was little change in the IO and furfuryl alcohol concentrations in water at 25 °C. The production of I in ice is due to the freeze concentration effect, which induces the accumulation of IO, furfuryl alcohol, and protons in the ice grain boundaries. This behavior facilitated the production of I via a redox reaction between IO and organic compounds. The production of I increased with increasing furfuryl alcohol concentration and decreasing pH. However, freezing temperature had a minor effect on the maximum production of I. The production of I is highly dependent on the type of organic compounds. It was higher for organic compounds with higher electron-donating properties. This study suggests a new mechanism for I production, which is helpful for predicting precisely the atmospheric I budget in cold regions.
碘酸盐（IO₃⁻）产生分子碘（I₂）的非生物机制在很大程度上仍然未知。在此，我们证明了在冰中存在IO₃⁻和有机化合物的情况下会产生I₂。当含有100 μM IO₃⁻和100 μM糠醇的溶液在pH 3.0时于-20°C冷冻，20分钟后产生了13.1 μM的I₂，且糠醇完全降解。然而，在25°C的水中，IO₃⁻和糠醇的浓度几乎没有变化。冰中I₂的产生是由于冷冻浓缩效应，该效应导致IO₃⁻、糠醇和质子在冰粒边界处积累。这种行为通过IO₃⁻与有机化合物之间的氧化还原反应促进了I₂的产生。I₂的产生随着糠醇浓度的增加和pH值的降低而增加。然而，冷冻温度对I₂的最大产量影响较小。I₂的产生高度依赖于有机化合物的类型。对于具有较高供电子性质的有机化合物，其产量更高。本研究提出了一种I₂产生的新机制，这有助于精确预测寒冷地区的大气碘收支。
