Atmospheric bromoform at Cape Point, South Africa: an initial fixed-point data set on the African continent

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Date

2018

Journal Title

Journal ISSN

Volume Title

Publisher

EGU

Abstract

Bromoform mixing ratios in marine air were measured at Cape Point Global Atmospheric Watch Station, South Africa. This represents the first such bromoform data set recorded at this location. Manual daily measurements were made during a month-long field campaign (austral spring 2011) using a gas chromatograph-electron capture detector (GC-ECD) with a custom-built front end thermal desorption trap. The measured concentrations ranged between 4.4 and 64.6 ( 22.2 %) ppt with a mean of 24.8 14.8 ppt. The highest mixing ratios recorded here occurred at, or shortly after, low tide. The diurnal cycle exhibited a morning and evening maximum with lower concentrations throughout the rest of the day. Initial analysis of the data presented indicates that the local kelp beds were the dominant source of the bromoform reported. A concentration-weighted trajectory analysis of the bromoform measurements suggests that two offshore source areas may exist. These source areas appear to be centred on the Agulhas retroflection and extend from St Helena Bay to the southwest.

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Keywords

Atmospheric bromoform, Cape Point Global Atmospheric Watch Station, Gas chromatograph-electron capture detector (GC-ECD), St Helena Bay, Africa

Citation

Kuyper, B., Palmer, C.J., Labuschagne, C. & Reason, C.J. C. (2018). Atmospheric bromoform at Cape Point, South Africa: an initial fixed-point data set on the African continent. Atmospheric Chemistry and Physics, 18(8), 5785–5797. https://doi.org/10.5194/acp-18-5785-2018