High concentrations of iodine oxide (IO) have been reported over west Antarctica, with areas around the Weddell Sea showing a peak in spring. However, stations in east Antarctica show much lower values during summer, although observations over spring are still missing. Here, we present the first year-long observations of IO outside the Weddell Sea region using a multi-axis differential optical absorption spectrometer (MAX-DOAS) over the Bharati station (69.41°S, 76.19°E). Observations show that iodine chemistry is less active than over the Weddell Sea, even during springtime, with IO mixing ratios below 2 pptv throughout the sunlit period. A slight increase in IO is observed in spring, although it is a factor of 10 lower than the Weddell Sea region. We identify the variations in drivers in the different regions using sea ice concentrations, sea ice thickness and chlorophyll concentrations. We use a global model which uses a parameterization for iodine emissions based on a combination of these factors. The model reproduces the high concentrations over the Weddell Sea and the low concentrations over Bharati throughout the year, shedding light on the environmental factors, sources and chemistry of iodine in Antarctica. Even at small concentrations, iodine can enhance ozone loss caused by bromine chemistry over east Antarctica, although this impact is lower than in the west Antarctic.

据报道，南极洲西部地区的碘氧化物 (IO) 浓度很高，威德尔海周围地区在春季达到峰值。然而，尽管春季的观测仍然缺失，但南极洲东部的站点在夏季显示的值要低得多。在这里，我们使用多轴差分光学吸收光谱仪 (MAX-DOAS) 在巴拉蒂站（南纬 69.41°，东经 76.19°）上首次对威德尔海地区以外的 IO 进行了为期一年的观测。观察显示，即使在春季，碘化学也比威德尔海的活跃度低，在整个阳光照射期间，IO 混合比低于 2 pptv。春季 IO 略有增加，但比威德尔海地区低 10 倍。我们利用海冰浓度、海冰厚度和叶绿素浓度来确定不同地区驱动因素的变化。我们使用一个全局模型，该模型根据这些因素的组合对碘排放量进行参数化。该模型再现了威德尔海全年的高浓度和巴拉蒂上空的低浓度，揭示了南极洲碘的环境因素、来源和化学性质。即使在低浓度下，碘也会加剧南极洲东部由溴化学引起的臭氧损失，尽管这种影响低于南极西部。