Institut des Sciences Moléculaires, Université de Bordeaux, UMR CNRS 5255, Talence Cedex 33405, France.
Institut de Radioprotection et de Sûreté Nucléaire (IRSN), PSN-RES, SEREX, Laboratoire Expérimentation Environnement et Chimie (L2EC), St Paul Lez Durance 13115, France.
Environ Sci Process Impacts. 2021 Nov 17;23(11):1771-1781. doi: 10.1039/d1em00266j.
Gaseous iodomethane (CHI) is naturally emitted into the atmosphere by biological activity in oceans and during severe accidents (SAs) in nuclear power plants. In this latter case, a part of radioactive iodine such as I may be released. Improving the knowledge of CHI transport and reactivity in the atmosphere is important since they are strongly linked to first the cycle of ozone and second to the dispersion of radioactive CHI with potential radiological consequences on both the environment and human health. Here, the interaction process of CHI with NaCl as a surrogate of atmospheric aerosols was investigated under ambient air conditions by using Diffuse Reflectance Fourier Transform Spectroscopy (DRIFTS). The DRIFTS spectra of NaCl clearly evidenced CHI adsorption on the NaCl particle surface. A part of CHI ((1.68 ± 0.85) × 10 molecule per mg) was found to be strongly bonded to NaCl since no desorption was observed. The CHI adsorption on the NaCl surface presented a 1 order kinetics relative to its gas phase concentration. The uptake coefficient was determined to be in the order of 10. These results show a low probability of CHI to be taken up by halide-containing aerosols. These data are crucial for completing the iodine atmospheric chemical scheme.
气态碘甲烷（CHI）通过海洋中的生物活动以及核电厂严重事故（SA）自然排放到大气中。在后一种情况下，可能会释放出一部分放射性碘，如 I。提高大气中 CHI 传输和反应性的认识非常重要，因为它们与臭氧循环以及放射性 CHI 的分散密切相关，这可能对环境和人类健康造成放射性后果。在这里，使用漫反射傅里叶变换光谱（DRIFTS）在环境空气条件下研究了 CHI 与 NaCl（作为大气气溶胶的替代物）的相互作用过程。DRIFTS 谱清楚地表明 CHI 吸附在 NaCl 颗粒表面上。发现一部分 CHI（（1.68 ± 0.85）× 10 个分子/毫克）与 NaCl 强结合，因为没有观察到解吸。CHI 在 NaCl 表面的吸附相对于其气相浓度呈 1 级动力学。吸收系数确定为 10 的数量级。这些结果表明 CHI 被含卤化物气溶胶吸收的可能性较低。这些数据对于完成碘大气化学方案至关重要。
