 What is the current status of acid deposition science in Canada ?
Environment Canada has released the 2004 Canadian
Acid Deposition Science Assessment which shows that despite Canada's success at reducing acid
causing emissions, acid deposition is still affecting our environment.
The 2004 Canadian Acid Deposition Science Assessment is a compilation of
scientific research and monitoring on acid deposition and its effects in
Canada. The assessment, conducted by experts from federal and provincial
governments and academia, presents the current state of knowledge of acid
deposition.
Despite widespread misconceptions that the acid rain issue is solved, new
research indicates that the problem is persistent. Between 21 and 75 percent
of eastern Canada, continues to receive levels of acid deposition in excess
of critical loads ( i.e. the amount of acid deposition that a particular
region can receive without being adversely affected). There is potential
for acid deposition to affect the long-term sustainability of Canada's
ecosystems.
It is estimated that on the order of a further 75% reduction in SO2 emissions
will be required from Canada and the U.S. , beyond those agreed to
in the Canada-US
Air Quality Agreement for
2010, in order to protect eastern Canadian ecosystems from damage by
acid deposition. At present, it is not possible to accurately assess the
extent to which acid deposition is affecting ecosystems in the west.
In Canada and the U.S. , major sources of acid-causing emissions are non-ferrous mining and smelting, electric power generation, upstream oil and gas operations, petroleum refining and transportation.
Acid deposition has negative impacts on lakes,
rivers
, soils, forests,
wildlife, biodiversity, buildings and human
health. For instance, 50% of the
boreal forest gets too much acid to remain healthy and productive into
the future. There is evidence to suggest that acid rain is currently
reducing the growth rate of trees in eastern Canada; it has been estimated
that over half a million cubic meters of wood, at a value of hundreds of
millions of dollars, is being lost from forests each year. Lakes and rivers
in the acid-sensitive regions of eastern Canada are generally remaining too
acidic or have not recovered to the point where they can support sensitive
fish and aquatic life. The decline in fish has impacts on the recreational
fishing industry.
There are, however, encouraging signs of improvements. Lakes in eastern
Canada located near smelters that have dramatically reduced their emissions
(Sudbury, Rouyn Noranda) provide the most definitive evidence of recovery,
measured as an increase in lake pH. Lakes in southeastern Canada show a general
decline in sulphur-derived acid which is the first sign that reductions in
acid-causing emissions are reducing levels of acid deposition.
Acid deposition is linked
to many other environmental issues, including SMOG and climate change.
Clearly, the problem of acid deposition is not solved yet.
The 2004 Canadian Acid Deposition Science Assessment:
Summary for Key Results
and the 2004 Canadian Acid Deposition Science Assessment are available at:
( http://www.msc-smc.ec.gc.ca/saib/acid/acid_e.html)
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