Release of volatile iodinated C1-C4 hydrocarbons by marine macroalgae from various climate zones

Marine macroalgae are known sources of a wide range of volatile brominated hydrocarbons, but before now far less attention was paid to their contribution to the input of volatile organoiodine compounds into the environment. In this work, 29 species of subtropic, temperate, and polar macroalgae were investigated for their release of volatile iodocompounds, lodoethane, 1-iodopropane, 2-iodopropane, 1-iodo-2-methylpropane, 1-iodobutane, 2-iodobutane, diiodomethane, and chloroiodomethane were identified and their release rates determined. Additionally, release rates of bromoform and dibromomethane were evaluated for comparison with release rates of iodinated compounds. The highest release rates were found for bromoform with up to 253 pmol g(-1) wet algal weight d(-1), followed by diiodomethane and dibromomethane with up to 29.3 and 18.3 pmol g(-1) wet algal weight d(-1), respectively. In contrast to bromoform, which was released in higher rates by subtropic macroalgae as compared to polar macroalgae, all iodinated compounds revealed lower release rates by macroalgae from subtropic regions, possibly due to decreasing stability of iodinated hydrocarbons at higher temperatures. The annual input of iodine into the atmosphere by macroalgae was estimated as 42 ton. Compared to a total global emission of 10(6) ton yr(-1), macroalgae apparently participate only in 0.005% of the total iodine emission. However, in coastal regions with high macroalgae biomass and in the polar environment, macroalgae may significantly contribute to the local input of iodine into the atmosphere.