Abstract Among various gaseous oxidized mercury species, HgCl2 and HgBr2 are known to be more recalcitrant to direct photolysis under radiations. In this study, we examined a possible route to reduce HgCl2 and HgBr2 in the dry air under UV, visible and solar radiations with different levels of irradiances. Potential impact of O3 on the reductions of HgCl2 and HgBr2 were discussed. The laboratory results showed that if without any radiation, O3 would not influence the chemical conversions between HgCl2/HgBr2 and Hg0. However, if with involvement of radiation, a rapid reduction of HgCl2 and HgBr2 was observed, resulting in a significant production of Hg0 in the air. The magnitudes of reduction reactions heavily depended on the frequency of radiations as well as the irradiances. UV light had the strongest capacity to promote photoreduction of HgCl2 and HgBr2 even at relatively low irradiances. A relationship analysis indicated that the reduction of HgCl2 and HgBr2 was possibly related to the O3 concentrations in the air. We proposed that O3 might be involved in productions of the unstable intermediate HgIX (X = Br, Cl), which has a quicker photolysis rate than the HgIIX2. Our results suggest that the impacts of solar radiation and O3 on reductions of HgII species in the atmosphere are worth of being investigated theoretically and in both laboratory and field studies in the future, since it might be an important but lesser-known part in the atmospheric Hg chemistry.

中文翻译：

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光解干燥空气中 HgCl2 和 HgBr2 的潜在途径及臭氧影响分析

摘要 在各种气态氧化汞物种中，已知 HgCl2 和 HgBr2 更难于在辐射下直接光解。在这项研究中，我们研究了在具有不同辐照度的紫外线、可见光和太阳辐射下减少干燥空气中 HgCl2 和 HgBr2 的可能途径。讨论了 O3 对 HgCl2 和 HgBr2 还原的潜在影响。实验室结果表明，如果没有任何辐射，O3 不会影响 HgCl2/HgBr2 和 Hg0 之间的化学转化。然而，如果涉及辐射，观察到 HgCl2 和 HgBr2 迅速减少，导致空气中大量产生 Hg0。还原反应的大小在很大程度上取决于辐射频率和辐照度。即使在相对较低的辐照度下，紫外光也具有最强的促进 HgCl2 和 HgBr2 光还原的能力。关系分析表明，HgCl2和HgBr2的减少可能与空气中O3浓度有关。我们提出 O3 可能参与不稳定中间体 HgIX (X = Br, Cl) 的产生，它比 HgIIX2 具有更快的光解速率。我们的研究结果表明，太阳辐射和 O3 对大气中 HgII 物种减少的影响值得在理论上以及实验室和实地研究中进行研究，因为它可能是大气中重要但鲜为人知的部分。汞化学。关系分析表明，HgCl2和HgBr2的减少可能与空气中O3浓度有关。我们提出 O3 可能参与不稳定中间体 HgIX (X = Br, Cl) 的产生，它比 HgIIX2 具有更快的光解速率。我们的研究结果表明，太阳辐射和 O3 对大气中 HgII 物种减少的影响值得在理论上以及实验室和实地研究中进行研究，因为它可能是大气中重要但鲜为人知的部分。汞化学。关系分析表明，HgCl2和HgBr2的减少可能与空气中O3浓度有关。我们提出 O3 可能参与不稳定中间体 HgIX (X = Br, Cl) 的产生，它比 HgIIX2 具有更快的光解速率。我们的研究结果表明，太阳辐射和 O3 对大气中 HgII 物种减少的影响值得在理论上以及实验室和实地研究中进行研究，因为它可能是大气中重要但鲜为人知的部分。汞化学。