Release of volatile iodinated C-1-C-4 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 contribut ion to the input of volatile organoiodine compounds into the environment. I n this work, 29 species of subtropic, temperate, and polar macroalgae were investigated for their release of volatile iodocompounds, lodoethane, 1-iod opropane, 2-iodopropane, 1-iodo-2-methylpropane, 1-iodobutane, 2-iodobutane , diiodomethane, and chloroiodomethane were identified and their release ra tes determined. Additionally, release rates of bromoform and dibromomethane were evaluated for comparison with release rates of iodinated compounds. T he 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 con trast to bromoform, which was released in higher rates by subtropic macroal gae as compared to polar macroalgae, all iodinated compounds revealed lower release rates by macroalgae from subtropic regions, possibly due to decrea sing 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 appare ntly participate only in 0.005% of the total iodine emission. However, in c oastal regions with high macroalgae biomass and in the polar environment, m acroalgae may significantly contribute to the local input of iodine into th e atmosphere.