Depletion of Ozone Layer by Iodine Oxides

Iodine plays a very important role in nature. It is an essential dietary element for mammals. It may affect the environment in many ways. It may enhence the depletion of ozone layer. It has the capacity to oxidize atmosphere and may remove various organic and inorganic species which emitted to atmosphere both from natural and anthropogenic sources. It may also enhance the depletion of mercury (Hg⁰) to reactive mercuric (Hg^II) compounds by oxidation into polar atmosphere. Oxidized mercury then deposited in snow pack, part of it may reduce and released back to atmosphere, but remaining part of it runs off in melt water and may enter to the food chain. Iodine and its compounds combine with ozone to form iodine oxides in the atmosphere, where they may form ultra fine aerosol particles having a diameter of 3-10 nm. These iodine oxide particles (IO and IO radicals) may combine to form higher oxides which then spontaneously condense to form particles.

                Bursts of iodine oxide particles also have been observed in certain marine environment. These particles may acts as condensation nuclei for other condensable vapours and acts as cloud condensation nuclei (CCN)  which would impact on the radiative balance of the atmosphere and hence on climate. It is also a mystery that what would happen when iodine oxide particles such as I₂O₃, I₂O₄, I₂O₅ and I₄O₉ may also combine with acids such as HCl, H₂SO₄, HNO₃, Oxalic acid etc. The uptake of inorganic iodine compounds, such as HOI and INO3 , on sea salt aerosols liberates chlorine and bromine into the gas phase, these halogens are also ozone depleting and their atoms and oxides are highly reactive towards certain organic compounds. As such our aim through our research work is to shed some light on the possible iodine species form in the atmosphere aerosol and their ice nucleation properties.