Organic iodine gases in the atmosphere and ocaen

·         　The illustration below shows the bio-geochemical cycle of iodine on the earth's surface. “org-I” refers to the organic iodine.    The organic iodine that is volatilized from the ocean to the atmosphere is organic iodine gas . Emissions of organic iodine gas from the ocean surface plays an important role in supplying iodine atoms to the atmosphere. Therefore, organic iodine gas in the atmosphere and surface of the ocean has long been investigated.

　The aforementioned illustration also includes org-I (gas) and org-I (solid) in the marine sediment layer. It is thought that the settlement of iodine-rich organic matter derived from marine plants on the seafloor results in the accumulation of iodine in the marine sediment. High concentrations of iodine are accumulated, as observed during the observation of methane gas layers deep underground in the Pacific coastal area of Chiba Prefecture. The large quantity of marine plants containing iodine that settled long ago is thought to be a reason for this accumulation. Some of this is thought to be organic iodine (org-I) because this iodine is present in sediments rich with organic matter. Therefore, we showed org-I (solid) as well, based on these assumptions.

　Our laboratory has firstly measured the organic iodine gas (org-I (gas)) in the sediment (began in 2018). We have been finding a lot mysteries about org-I gas in the sediment.