New Greenhouse Gas
Identified by Mass Spectrometry
An international
team of environmental researchers have
discovered a potentially new greenhouse
gas, trifluoromethyl sulfur pentafluoride
(SF5CF3), after studying
stratospheric air samples by gas
chromatography-mass spectrometry
(GC-MS).
The gas which exists
in the stratosphere at concentrations of
about 0.1 parts per trillion has the
largest greenhouse warming potential of
any gas found in the atmosphere at up to
17500 times that of carbon dioxide on a
per-molecule basis. The unsettling
discovery, is that the atmospheric
concentration of the compound is
increasing by about 6% per year. This is
alarming given that SF5CF3 has a lifetime of about
1,000 years.
According to
researchers, the way in which
SF5CF3 entered the atmosphere is
still unknown, but the chemical itself is
certainly of human origin. The researchers
speculate that the compound is the
breakdown product of sulfur hexafluoride,
SF6, a gas used in electrical
switches to suppress sparks and in the
production of tennis balls and automobile
tyres. Its potential precursor SF6 is a
well-known greenhouse gas whose production
is restricted under the "Kyoto Protocol",
an international agreement to control
greenhouse gases.
Concluding their
paper in the July 28 issue of Science
magazine,
the researchers write that "we think that
it is important to continue monitoring the
atmospheric concentration of
SF5CF3 in order to determine and
control its sources and to guard against
its accumulation in the
atmosphere."