Sulphur Dioxide (SO2)
Sulphur dioxide (SO2) is a colourless gas with a pungent
odour. In Alberta, natural gas processing plants are responsible for
close to half of the SO2 emissions in the province. The oil
sands facilities and power plants are also major SO2 sources.
Other sources include gas plant flares, oil refineries, pulp and paper
mills and fertilizer plants.
Monitoring Method
SO2 is monitored continuously by pulsed fluorescence. In
this method, air is drawn through a sample chamber where it is irradiated
with pulses of ultra-violet light. Any SO2 in the sample
is excited to a higher energy level and upon returning to its original
state, light or fluorescence is released. The amount of fluorescence
measured is proportional to the SO2 concentration.
Objectives
Alberta Environment has adopted Environment Canada's most rigorous Objectives
for sulphur dioxide. The following Objectives are based on prevention
of effects to vegetation:
- 0.172 ppm as a 1-hour average concentration;
- 0.057 ppm as a 24-hour average concentration; and
- 0.011 ppm as an annual average concentration.
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