Release of Volatile Iodinated C₁−C₄Hydrocarbons by Marine Macroalgae from Various Climate Zones

Abstract

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. Iodoethane, 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.

Long-term halocarbon observations from a coastal and an inland site in Sabah, Malaysian Borneo

“…The instrument is described in detail in Gostlow et al (2010). Briefly, each sample is pre-concentrated using a dual-bed adsorbent trap (1 mg Carboxen-1016 60/80 mesh followed by 1 mg Carboxen-569 20/45 mesh).…”

Application of Gas Chromatography to Exuded Organic Matter Derived from Macroalgae

“…Although GC-ECD has been commonly applied, it is necessary to confirm the retention time of each compound using authentic standards (Giese et al, 1999) or GCMS (Manley and Dastoor, 1987) to identify each component. On the other hand, application of GCMS has an advantage that it is reliable to characterize the compounds based on the mass spectrum.…”

Isotopic composition of polyhalomethanes from marine macrophytes – systematic effects of the halogen substituents on isotopic composition

“…Marine macroalgae have long been recognised as potent sources of diverse halocarbons and their production has been studied in numerous laboratory and field experiments. [16][17][18][19][20][21][22][23][24][25] More recently, seagrass meadows have also been recognised as halocarbon sources. [26,27] Brown algae -particularly from the order Laminariales -produce a wide range of polyhalomethanes (PHMs).…”

“…[16,22,23] Furthermore, production of monohalomethanes, e.g. CH 3 I, [18,24] and of several iodinated and brominated C 2 to C 4 monoalkylhalides [21,24] has been observed. The biogenic formation of PHMs proceeds by an enzyme-catalysed halogenation of organic substrates having an activated a-carbon atom, most likely b-diketones or b-ketoacids.…”