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