Sources and fluxes of volatile halogenated compounds in highly productive marine areas

Abstract : Volatile halogenated organic compounds (VHOCs) constitute a large group of environmental gases that can influence atmospheric chemistry, and have natural and anthropogenlc sources, Marine sources and fluxes, and biogenic production are poorly investigated. During this thesis we designed an analytical system and sampling devices for measurements of halocarbons which showed high performance, both at sea and during laboratory analyses. In a laboratory experiment it could be demonstrated that plant-plant communication orchestrates the formation of VHOCs: “forewarned” algae react less intensely after perception of an oligoguluronates signal. This might be beneficial for the algae in terms of cost efficiency. Two highly productive marine areas were studied for VHOC distribution and air-sea fluxes: a diatom dominated upwelling region and a nutrient enriched coastal region with an important macroalgae cover and a mega-tidal regime. The main findings are (1) upwelling regions are not characterized by high internal VHOC formallon, (2) in tidal-lnfiuenced marine areas tides have significant effects on the formation of iodo- and bromocarbons but no influence on the formation of chlorocarbons (with the exception of chloroform, which showed minor dependence on tides in the Iberian upwelling), (3) bromocarbons have strong and highly localized coastal sources (4) iodocarbons have sources that are not strictly related to macroalgae, (5) main sources of chlorocarbons might have an anthropogenic origin and (6) formation of halocarbons and their fluxes to the atmosphere show a marked seasonality.
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  • HAL Id : tel-01112564, version 1

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Stefan Raimund. Sources and fluxes of volatile halogenated compounds in highly productive marine areas. Organic chemistry. Université de Bretagne Occidentale, 2010. English. ⟨tel-01112564⟩

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