Université de Lyon 1, Lyon, Institut de Recherches sur la Catalyse et l'Environnement de Lyon, Centre National de la Recherche Scientifique, Unité Mixte de Recherche 5256, Villeurbanne F-69626, France.
Proc Natl Acad Sci U S A. 2012 Dec 18;109(51):20842-7. doi: 10.1073/pnas.1212297109. Epub 2012 Dec 3.
Large quantities of mineral dust particles are frequently ejected into the atmosphere through the action of wind. The surface of dust particles acts as a sink for many gases, such as sulfur dioxide. It is well known that under most conditions, sulfur dioxide reacts on dust particle surfaces, leading to the production of sulfate ions. In this report, for specific atmospheric conditions, we provide evidence for an alternate pathway in which a series of reactions under solar UV light produces first gaseous sulfuric acid as an intermediate product before surface-bound sulfate. Metal oxides present in mineral dust act as atmospheric photocatalysts promoting the formation of gaseous OH radicals, which initiate the conversion of SO(2) to H(2)SO(4) in the vicinity of dust particles. Under low dust conditions, this process may lead to nucleation events in the atmosphere. The laboratory findings are supported by recent field observations near Beijing, China, and Lyon, France.
大量的矿物尘埃颗粒经常通过风的作用被喷射到大气中。尘埃颗粒的表面充当了许多气体（如二氧化硫）的汇。众所周知，在大多数条件下，二氧化硫在尘埃颗粒表面发生反应，导致硫酸根离子的生成。在本报告中，针对特定的大气条件，我们提供了证据，表明在太阳紫外线的照射下，一系列反应会首先产生气态硫酸作为中间产物，然后才在表面形成硫酸盐。矿物尘埃中存在的金属氧化物作为大气光催化剂，促进了气态 OH 自由基的形成，从而在尘埃颗粒附近启动了 SO(2)向 H(2)SO(4)的转化。在低尘埃条件下，这个过程可能导致大气中的成核事件。实验室的发现得到了中国北京和法国里昂附近最近的实地观测结果的支持。
