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The new Shand Power Station near Estevan is addressing the acid
rain problem with new emission reducing technology. A Limestone
Injection into Furnace and Activation of unreacted Calcium (LIFAC)
system controls sulphur dioxide emissions. Low NOX burners substantially
reduce emissions of nitrous oxides. Since sulphur dioxide and
nitrous oxides are precursors to acid rain formation, controlling
their production and escape into the atmosphere will help control
acid precipitation in Saskatchewan and the surrounding areas.
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Field and laboratory experiments have been conducted to study
acid precipitation damage to leaves. Most of these experiments
involve spraying of artificial precipitation solutions directly
onto leaf surfaces. At extremely low pHs of less than 3.5, lesions
(small areas of dead cells), pitting (holes in leaf waxes), and
leaf curling can be induced. The degree of the damage often depends
on such physical characteristics as the thickness of waxes present
on the upper surface of the leaf. Plants with a thick coating
of wax may be protected from acid precipitation damage because
water droplets tend to roll off. In addition, the leaves of many
species have inherent neutralizing or buffering ability. However,
it has been shown that precipitations of low pH can actually dissolve
surface waxes.
Acid precipitation has also been linked to nutrient disturbances
and changes in soil chemistry and damage to the root systems of
forest trees. Studies have shown that if the pH of the soil solution
reaches 4.0, heavy metals naturally present in an inert form in
soil particles may be mobilized and become an active part of the
soil solution. Aluminum, which is available in high concentration
in soils derived from granitic bedrock, is one metal that can
be activated in this way. Aluminum is toxic to plant root systems
and may be responsible for death of the small feeder roots, which
supply most of the water and nutrients required by the tree. |
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