Emission of iodine-containing volatiles by selected microalgae species

摘要

In this study we present the results of an emission study of different phytoplankton samples in aqueous media treated with elevated ozone levels. Halocarbon measurements show that the samples tested released bromoform and different iodocarbons, including iodomethane, iodochloromethane and diiodomethane. Iodide and iodate levels in the liquid phase were representative of concentrations of surface water in a natural environment. Measurement of volatile iodine (Isub2/sub) emissions from two diatom samples (iMediopyxis helysia/i and iPorosira glacialis/i) and the background sample (F/2 medium from filtered natural seawater) showed that the quantity of evolved Isub2/sub depends on the ozone concentration in the air. This behaviour was assumed to be caused by the oxidation reaction mechanism of iodide with ozone. The Isub2/sub emission flux agrees with model calculations at different iodide concentrations. The Isub2/sub emission of a natural plankton concentrate sample was, however, very low compared to other samples and showed no dependence on ozone. The reason for this was shown to be the low iodide concentration in the algal suspension, which seems to be the limiting factor in the oxidative formation of Isub2/sub.