Atmospheric bromoform at Cape Point, South Africa: an initial fixed-point data set on the African continent
Date
2018Author
Kuyper, Brett
Palmer, Carl J.
Labuschagne, Casper
Reason, Chris J. C.
Metadata
Show full item recordAbstract
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.