Haloacetates in precipitation

Sammanfattning: Haloacetates are a group of fluorinated, chlorinated and brominated organic compounds that pose a potential threat to the environment, because they are present in relatively high concentrations in precipitation and they are toxic to plants. At the time the research described in this thesis was begun, it had been suggested that atmospheric degradation of chlorinated solvents and CFC replacements were responsible for the presence of haloacetates in precipitation in populous regions. Thus, snow and rain from remote areas around the world were analysed to ascertain the global distribution of haloacetates. Moreover, natural archives of precipitation were studied to determine how long haloacetates have been present in precipitation. Ice was collected from two sub-polar glaciers in northern Sweden, and a 20-m firn core was drilled in Dronning Maud Land, Antarctica, exclusively for the purpose of analysing haloacetates. Analysis of fresh snow and rain showed that all three chloroacetates and trifluoroacetate (TFA) were ubiquitous in precipitation in both industrial and remote areas; typical concentrations in remote regions ranged from a few to a few hundred nanograms per litre. Furthermore, bromoacetates (MBA and DBA) were found in fresh snow from Antarctica. Chloroacetates, TFA and DBA were present at all depths in the Antarctic firn core, in particular in layers that had accumulated at the beginning of the 19th century, long before large-scale industrial production of the alleged anthropogenic precursors. Hence it can be concluded that natural sources play a significant role in the global distribution of haloacetates.

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