Methyl iodine over oceans from the Arctic Ocean to the maritime Antarctic

Studies about methyl iodide (CH(3)I), an important atmospheric iodine species over oceans, had been conducted in some maritime regions, but the understanding of the spatial distribution of CH(3)I on a global scale is still limited. In this study, we reports atmospheric CH(3)I over oceans during the Chinese Arctic and Antarctic Research Expeditions. CH(3)I varied considerably with the range of 0.17 to 2.9 pptv with absent of ship emission. The concentration of CH(3)I generally decreased with increasing latitudes, except for higher levels in the middle latitudes of the Northern Hemisphere than in the low latitudes. For sea areas, the Norwegian Sea had the highest CH(3)I concentrations with a median of 0.91 pptv, while the Central Arctic Ocean had the lowest concentrations with all values below 0.5 pptv. CH(3)I concentration over oceans was affected by many parameters, including sea surface temperature, salinity, dissolved organic carbon, biogenic emissions and input from continents, with distinctive dominant factor in different regions, indicating complex biogeochemical processes of CH(3)I on a global scale.