Koenig Theodore K, Volkamer Rainer, Apel Eric C, Bresch James F, Cuevas Carlos A, Dix Barbara, Eloranta Edwin W, Fernandez Rafael P, Hall Samuel R, Hornbrook Rebecca S, Pierce R Bradley, Reeves J Michael, Saiz-Lopez Alfonso, Ullmann Kirk
Department of Chemistry, University of Colorado Boulder, Boulder, CO, USA.
Cooperative Institute for Research in Environmental Sciences, Boulder, CO, USA.
Sci Adv. 2021 Dec 24;7(52):eabj6544. doi: 10.1126/sciadv.abj6544. Epub 2021 Dec 22.
Iodine is an atmospheric trace element emitted from oceans that efficiently destroys ozone (O). Low O in airborne dust layers is frequently observed but poorly understood. We show that dust is a source of gas-phase iodine, indicated by aircraft observations of iodine monoxide (IO) radicals inside lofted dust layers from the Atacama and Sechura Deserts that are up to a factor of 10 enhanced over background. Gas-phase iodine photochemistry, commensurate with observed IO, is needed to explain the low O inside these dust layers (below 15 ppbv; up to 75% depleted). The added dust iodine can explain decreases in O of 8% regionally and affects surface air quality. Our data suggest that iodate reduction to form volatile iodine species is a missing process in the geochemical iodine cycle and presents an unrecognized aeolian source of iodine. Atmospheric iodine has tripled since 1950 and affects ozone layer recovery and particle formation.
碘是一种从海洋中释放的大气微量元素，它能有效破坏臭氧（O）。在空气中的尘埃层中经常观测到低臭氧水平，但人们对此了解甚少。我们发现尘埃是气相碘的一个来源，这由飞机对来自阿塔卡马沙漠和塞楚拉沙漠扬起的尘埃层内一氧化碘（IO）自由基的观测所表明，这些尘埃层中的一氧化碘比背景值高出一个数量级。需要与观测到的IO相符的气相碘光化学过程来解释这些尘埃层内的低臭氧水平（低于15 ppbv；最多减少75%）。添加的尘埃碘能够解释区域内臭氧8%的减少，并影响地表空气质量。我们的数据表明，碘酸盐还原形成挥发性碘物种是地球化学碘循环中一个缺失的过程，并且呈现出一种未被认识的风尘碘源。自1950年以来，大气中的碘增加了两倍，影响臭氧层恢复和颗粒物形成。
