I'm investigating biological sources of iodine emissions in the sea ice zone.
High mixing ratios of iodine monoxide (IO) have been measured in the atmosphere over the sea ice of the southern ocean, the same cannot be said of similar environments in the northern hemisphere.
Diatoms (a species of phytoplankton) are known to emit organic compounds which contain iodine, once in the atmosphere these compounds are
photolysed by solar radiation to yield iodine radicals, which react with tropospheric ozone, destroying it
catalytically. New particles in the boundary layer may result from self reaction of the iodine oxides subsequently formed. Diatoms are known to colonise brine channels in sea ice, formed by brine expulsion as the ice freezes. I am trying to show that the
iodocarbons emitted by diatoms living in the brine channels make their way up through the channels and are emitted into the atmosphere.
In order to do this I am making measurements on sea ice at both ends of the earth - earlier this year I was involved in the COBRA (
COmbined impact of Bromine and Reactive halogens in the Arctic) field campaign in Hudson Bay in Canada, and in January 2009 I set sail for Antarctica on board the HMS Endurance!
Whilst in the field I make cores in sea ice and measure temperature and salinity to help ascertain if the brine channels form a continuous network which could provide a transport route from organisms living in the ice to the ice-atmosphere interface. I measure the chemical composition of the ice, including
iodocarbon concentrations by gas chromatography - mass spectrometry (
GC-MS) and iodide /
iodate ratios by cyclic
voltammetry and spectrophotometry respectively. I also look at diatom distribution the sea ice using microscopy, chlorophyll a and
fucoxanthin analysis.
Brine, snow and ultra-fine particles are studied
in order to investigate the mechanism by which emissions from diatoms in the sea ice zone may impact the chemistry and aerosol content of the overlying atmosphere.
Trecking out across the ice to make cores, well protected against the cold - temperatures dropped down to -40C on some days
The kites we used to fly ozone- and met-sondes to measure ozone and profile the atmopshere. When wind speeds were too low to fly kites we used balloons.
