Human Sources of Sulfur Oxides:
In 1980, emissions of sulfur dioxide totaled 24.1 million
tons in the United States. Of this total 66 % came from electric
power companies. Electric power companies that burn coal are
a major source of sulfur oxides. Other industrial plants contributed
about 22 %.
Smelting of metals such as copper, zinc, lead, and nickel
can produce large amounts of sulfur dioxide. In Canada, 45% of
the emissions are from smelting operations, compared to only
6 % in the United States.
Coal contains mainly carbon with some hydrogen. When coal
is burned it reacts with oxygen in the air to produce carbon
dioxide and water and large amounts of heat.
C + O2 --> CO2
In addition, coal may contain from 1-4 % of the element, sulfur.
When the coal is burned with oxygen in the air, the sulfur is
reacted to form sulfur dioxide.
S + O2 --> SO2