Source of Iodine oxide gas responsible for destruction of ozone over oceans identified

January 17, 2013

Scientists at the University of York and Leeds in Britain have established that the majority of ozone-depleting gas iodine oxide observed over the remote ocean comes from a previously unknown marine source. As per researchers, the main source of iodine oxide can be explained by emissions of hypoiodous acid (HOI) – a gas not yet considered as being released from the ocean – along with a contribution from molecular iodine.

Since the 1970s when methyl iodide (CH3I) was discovered as everywhere in the ocean, the presence of iodine in the atmosphere has been understood to come mainly from emissions of organic compounds from phytoplankton — microscopic marine plants.

As per latest research, reactive iodine, along with bromine, in the atmosphere is accountable for the destruction of huge amounts of ozone – around 50 % more than estimated by the world’s most advanced climate models – in the lower atmosphere over the tropical Atlantic Ocean. Scientists quantified gaseous emissions of inorganic iodine following the reaction of iodide (compound of iodine with another element or group) with ozone in a series of lab experiments and formation of both molecular iodine and HOI.
Researchers call it a self destruction mechanism, where more concentration of ozone leads to formation of more halogen gases which in turn destroy it.

This reaction could be responsible for around 75% of observed iodine oxide levels over the tropical Atlantic Ocean.

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