Post on 15-Jan-2016
description
Using Critical Loads to Protect Using Critical Loads to Protect Canadian Ecosystems from Canadian Ecosystems from
Damage due to Acid DepositionDamage due to Acid Deposition
Kerri Timoffee*Environment Canada Transboundary Air Issues Branch, Ottawa
(* plus a many others, e.g., Silvina Carou, Dean Jeffries,Mike Moran, C.-H. Ro, R.J. Vet)
WESTAR Council
Understanding the Critical Loads ApproachDenver, November 15-16, 2005
OutlineOutline Post-2000 Acid Rain Strategy How we got there
Scientific evidence of impacts, basis for 1982 deposition targets & decision process
control programs and anticipated ecological benefits Current status
2004 Canadian Acid Deposition Science Assessment Current situation with respect to critical loads
Next Steps Forecasting the future Where to next
Canada’s current policy instrument is the Canada’s current policy instrument is the 1998 1998 Canada-Wide Acid Rain Strategy for Canada-Wide Acid Rain Strategy for
Post-2000Post-2000 Signed by all Federal/Provincial/Territorial
Energy and Environment Ministers Main elements
Reduce acidifying emissions in eastern Canada and the United States
Prevent pollution and keep clean areas clean Maintain an adequate science and monitoring
program Report annually
Long term goal is to reduce acid deposition to below critical loads across Canada
Early scientific evidence forEarly scientific evidence forecological impacts in Canadaecological impacts in Canada
acidic lakes, damage to terrestrial vegetation near smelters, Gorham and Gordon, 1960
acidification damage in cottage country far from local emission sources, Dillon et al, 1977
decrease in number and variety of fish species in lakes and rivers of Ontario and the Atlantic provinces, BRCG, 1979
Canada realised that controlling acid Canada realised that controlling acid deposition would require an effects-based deposition would require an effects-based
programprogram Large but local sources Worlds’ tallest
“superstack” was built Air quality standard
addresses local air pollution problem
missed the problem of damage downwind & cumulative exposures
Sulphate loadings and observed effects Sulphate loadings and observed effects as basis for defining deposition targetsas basis for defining deposition targets
Area Loading (Kg/Ha*Yr)
Observations
I.L.W.A.S. Project, Adirondacks
40 Acidified lakes in the area
Southern Norway 20-40 Acid lakes, fish populations lost
Hubbard Brook, New Hampshire
35 Acid lakes in the area
Muskoka-Haliburton, Ontario
30 pH depression, evidence of biological damage
Algoma 20 Acidic headwater lakes Nova Scotia 20 Acidified Rivers Minnesota Boundary Waters
14 Some pH depression, no biological effects reported
ELA, Northeastern Ontario
10 No apparent detrimental effects observed in 10 yrs of study
Canada adopted a critical load toCanada adopted a critical load toprotect aquatic ecosystems in 1982protect aquatic ecosystems in 1982
aquatic evidence was sufficient forest damage was, and still is, controversial experimental cause-effect evidence of the
chemical processes and sequence of biological changes as acidification progressed
targeted wet sulphate deposition In 1982, Canada proposed a critical load of 20
kg/ha/yr to protect all but the most sensitive areas
In 1983 New England Governors and Eastern Canadian Premiers endorsed the 20kg/ha/yr target.
Projected impact of reducing SOProjected impact of reducing SO22 emissions emissions on the amount of wet sulphate deposited on the amount of wet sulphate deposited
annuallyannuallyWet sulphate deposition (approx. kg/ha/yr)
Estimated effects of reducing SO2 emissions by
Area Now50% inCanada
100% in Canada
50% in Canada
50% in US
Muskoka’s 29-35 24-30 20-26 13-19
Quebec City 27-35 23-31 19-27 15-23
Central Nova Scotia
17-23 16-22 14-20 15-20
Adirondacks 29-37 26-34 23-31 13-21
Vermont/New Hampshire
20-30 17-27 15-25 10-20
Emission Reduction Control Emission Reduction Control ProgramsPrograms
1984 Sulphur Protocol 30% reduction in SO2 emissions national cap of 3.2 million tonnes beginning in 1993 no particular environmental limit
1985 Eastern Canada Acid Rain Program plan to reduce total national emissions by 30% over
the next ten years, about 50% of the emissions in Eastern Canada
Goal to protect moderately sensitive aquatic ecosystems
Committed to further science 1991 Canada-US Air Quality Agreement
reiterated the national cap
Reporting indicated that both Reporting indicated that both countries would meet their targets countries would meet their targets
for emission reductions, so the for emission reductions, so the expectation was for ecosystems to expectation was for ecosystems to
improveimprove Expectation that aquatic and
terrestrial ecosystems would recover significantly
Perhaps restore the most sensitive aquatic ecosystems
Canada developed new critical Canada developed new critical loads to fully protect all surface loads to fully protect all surface
waterswaters
Critical load values (kg/ha/yr) of sulphate in precipitation
<=8
8 < <=12
<=1610 <
16 <
<=20
20 <
Even with full implementation of Canadian and Even with full implementation of Canadian and US programs, almost 800,000 kmUS programs, almost 800,000 km22 in in
southeastern Canada would still receive harmful southeastern Canada would still receive harmful levels of acid depositionlevels of acid deposition
Area of eastern Canada expected to receive wet SO4 deposition above critical loads (in kilograms per hectare per year) in 2010, without further controls beyond provisions in the 1991 Canada-US Air Quality Agreement
These critical loads and exceedance estimatesThese critical loads and exceedance estimateswere accepted by the scientific andwere accepted by the scientific and
political communities as the basis for developingpolitical communities as the basis for developingthe Post-2000 Acid Rain Strategythe Post-2000 Acid Rain Strategy
Strategies goal is to achieve sulphate deposition levels that do not exceed “critical loads”
Scenario modelling predicted the changes in critical load exceedances resulting from further reductions in SO2 emissions in eastern Canada as well as the US
25% cut in SO2 emissions → 34% reduction in area receiving harmful levels
50% cut in SO2 emissions → 72% reduction 75% cut → virtually all of eastern Canada
would be protected from acid deposition
Current Status - Time SeriesCurrent Status - Time SeriesCAPMoN and CASTNet NetworksCAPMoN and CASTNet Networks
Current status - Changes in Current status - Changes in nssSOnssSO44
== Wet Deposition Patterns Wet Deposition Patterns
1996-2001 Mean nssSO4= Wet Deposition (Kg/Ha/Yr)1980-1984 Mean nssSO4= Wet Deposition (Kg/Ha/Yr)
Aquatic CLsAquatic CLs
5th percentile value for all lakes located within a grid square
Index map shows which model produced the grid value 1983 target load (20 kg/ha/yr) covered by lowest four
classes 21% of eastern grid squares in lowest CL category
Area of Eastern Canada at RiskArea of Eastern Canada at Riskfrom Acid Depositionfrom Acid Deposition
0.5 million km2
1.8 million km2
New science considers both sulphate and nitrate deposition and aquatic and terrestrial ecosystems.
Aquatic “N-leaching” Aquatic “N-leaching” ExceedancesExceedances
95th exceedance value for all lakes within a grid square Current situation (note both positive and negative
exceedance classes) Largest (orange) exceedances occur in southern NS/NB and
ON Positive exceedance even occur in NW ON (but none in west)
Forecasting the FutureAnnual Effective Acidity Wet Deposition
(combined annual SO4 and NO3 wet deposition)
“First generation” Can-US SO2 and NOX emissions reductions
Most realistic Can-US SO2 and NOX emissions reductions
Implementation of current (e.g. Post-2000 Strategy) and proposed (e.g. U.S. Clear Skies) legislation is predicted to reduce the effective acidity of wet deposition by at least 30% over much of eastern North America by 2020.
keq/ha/yr
keq/ha/yr
Forecasting the FutureForecasting the Future
Implementation of current (e.g. Post-2000 Strategy) and proposed (e.g. U.S. Clear Skies) legislation, will reduce but not eliminate acid damage in eastern Canada.
Aquatic Terrestrial
It is estimated that a further reduction in SO2 of ~75% will be required from Canada and the U.S. beyond those agreed to in the Canada-U.S. Air Quality Agreement to end acid rain.
Draft Draft
Where to NextWhere to Next
New critical loads and preliminary exceedance estimates
Adjust our control control actions Further domestic cuts Decrease TB flows Increase effort at KCAC/PP
Monitor and report on ecological benefits
SummarySummary Concept of working towards reducing
deposition to below critical loads has long been central to Canada’s SO2 management program
There are still many regions of eastern Canada (and perhaps even small parts of western Canada) where present-day deposition levels exceed aquatic critical loads
Developing critical loads is an iterative process
ChallengesChallenges
Concern that any sulphur dioxide control program would require large, and possibly expensive, reductions
Region ofRegion ofConcern:Concern:
WhereWhere Ecosystem Ecosystem
EffectsEffectsLikely Likely OccurOccur
(contains ~800000 water bodies)
Environment Canada (1988)
Contact informationContact information
Kerri TimoffeeManager, Acid Rain Program
Transboundary Air Issues BranchEnvironment Canada
Rm 1118, 351 St Joseph BlvdGatineau, Quebec K1A 0H3
Email: kerri.timoffee@ec.gc.caTelephone: (819) 994-9564
Fax: (819) 953-8963