The effect of desiccation on the emission of volatile bromocarbons from two common temperate macroalgae

[摘要] Exposure of intertidal macroalgae during low tide has been linked to theemission of a variety of atmospherically-important trace gases into the coastalatmosphere. In recent years, several studies have investigated the role ofinorganic iodine and organoiodides as antioxidants and their emission duringexposure to combat oxidative stress, yet the role of organic bromine speciesduring desiccation is less well understood. In this study the emission ofdibromomethane (CH₂Br₂) and bromoform (CHBr₃) during exposureand desiccation of two common temperate macroalgae, Fucus vesiculosus and Ulva intestinalis, is reported.Determination of the impact exposure may have on algal physiologicalprocesses is difficult as intertidal species are adapted to desiccation andmay undergo varying degrees of desiccation before their physiology isaffected. For this reason we include comparisons between photosyntheticcapacity (F_v/F_m) and halocarbon emissions during a desiccationtime series. In addition, the role of rewetting with freshwater to simulateexposure to rain was also investigated. Our results show that an immediateflux of bromocarbons occurs upon exposure, followed by a decline inbromocarbon emissions. We suggest that this immediate bromocarbon pulse maybe linked to volatilisation or emissions of existing bromocarbon stores fromthe algal surface rather than the production of bromocarbons as anantioxidant response.

[学科分类] 地球化学与岩石