Calculate, map and used of critical loads and exceedances for
acidity and nitrogen in Europe
Professor Harald Sverdrup Chemical Engineering, Lund University,
The European game planEnvironmental policyand future visions
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Quantitativecause limitation
Ecosystem
Indicator organism
Critical limit
Calculation method
Data
An effect-based methodology
Defining the critical load
• The maximum amount of pollution into an ecosystem that does not cause significant damage to system resources, survival, structure or function
The critical load
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Contributions toacidity in the system
Contributions toneutralization inthe system
Targets to protectFor Sweden, it is proposed that the aspects to protect are:
1 Tree vitality and growth potential for the major species used in production,2 The potential for natural rejuvenation of the tree vegetation3 Fertility aspect of the soil as expressed by the base saturation,4 Biodiversity of the ground vegetation
For aquatic ecosystems the aspects to protect are suggested to be:
3 The most sensitive fish species native to the waterbody4 Crayfish in those waterbodies it is native to5 The biodiversity of the aquatic community, evaluating the range of organisms native to
the systemTabulated values are available for limiting BC/Al ratios for trees, ground vegetationand crops, as well as their corresponding pH values.
Response was
measured
Norway spruce: BC/Al=1.2Scots pine: BC/Al=1.0Birch: BC/Al= 0.8 Beech, Oak: BC/Al==0.6
Many effect parameters are available
EcosystemType
Ecosystemcomponent
Indicatororganism
Indicatorfunction
Causativeparameter
Limitingvalue
DiagnosticMonitoringparameter
Forestecosystem
Tree cover NorwaySpruce
Root vitality,Growthpotential
(Ca+Mg+K)/AlpH
[Al3+]
1.24.4
0.5 mg/l
Growth,Needle loss, Tree
vitalityNatural
rejuvenation(Ca+Mg+K)/Al
pH[Al3+]
0.73.9
1 mg/l
Rejuvenationrate,
Species longterm survival
Scots pine Root vitality,Growthpotential
(Ca+Mg+K)/AlpH
[Al3+]
1.24.4
0.5 mg/l
Growth,Needle loss, Tree
vitalityNatural
rejuvenation(Ca+Mg+K)/Al
pH[Al3+]
0.6,3.9
1 mg/l
Rejuvenationrate,
Species longterm survival
Models available for critical loads for acidity and nitrogen
• Empirical models– Skokloster model– Empirical nitrogen critical loads
• Simplified models– Simple mass balance (SMB)– F-factor models (lakes)
• Integrated steady state models– PROFILE model
• Integrated dynamic models– VSD model (soils)– MAGIC model family (lakes)– SAFE/ForSAFE-VEG model family (terrestial ecosystems)
The order of the actions
• Static approach first
- Simple mass balance models
- Complex approach; PROFILE
- Create critical loads maps
• Apply dynamic models at sites with enough data
- Single sites - qualitative assessments
- Generate regional approach - representative
information capture and transformation
PROFILE/ForSAFE
Revised critical loads for forests, lakes and streams
meq per m2 och årCLacid ( 5%-tile)
36 0 to 1077 10 to 2062 20 to 40
10 40 to 603 60 to 1004 100 to 2001 200 to 500
meq per m2 och årCLnut ( 5%-tile)
21 0 to 1083 10 to 2060 20 to 40
24 40 to 605 60 to 1000 100 to 2000 200 to 500
Critical Load for acidity and nitrogen in the grid system
Critical loads for ecosystems in Europe, forests, open land and lakes
The best solution is sought for
Critical loadsfor ecosystems
Emissions of pollutants Reduction cost
Transport ofpollution acrossborders
Optimization formaximum protection,minimum reduction cost
The policy for pollution control
1988, kEq per ha and yrExceedance (50%-tile)
20 - to 0.037 0.0 to 0.2
50 0.2 to 0.565 0.5 to 1.0
19 1.0 to 20.0
1988, kEq per ha and yrExceedance (5%-tile)
8 - to 0.021 0.0 to 0.2
38 0.2 to 0.565 0.5 to 1.059 1.0 to 20.0
The Swedish example1988 exceedence was far too much !
Forest growth and vitalityBC/Al=0.6-1.2
Protection of nutrient resourcesAcid input>Weathering
Lakes and streamsmax Al: 0.06 mg/l
Medel: 37 mekv/m2/år
Exceedance depend on the receptor chosen
Exceedence 2010 (50%-tile)meq per m2 och år
149 -300 to 035 0 to 10
6 10 to 202 20 to 401 40 to 600 60 to 800 80 to 150
meq per m2 och årExeedence 1997 ( 5%-tile)
59 -300 to 064 0 to 10
37 10 to 2026 20 to 40
3 40 to 601 60 to 803 80 to 150
Exceedance with the Göteborg protocol
Sulfur deposition 1980-2010
• Green = 3-6 kg S/ha yr• Red > 25 kg S/ha yr
Exceedance of critical loads
• Blue < 3 kg S/ha yr• Red > 25 kg S/ha yr
Critical loads cannot be validated,but the components of it can be testedand validated
Exceedance cannot be robustly tested againstecosystem effects, because ecosystem effectsare not uniquely defined by exceedance
Validation is difficult
Exceedance and effects are NOT simultaneous in time
Critical load isexceeded
Limit is violateddamage possible
Deposition
Limit parameter
TIME
LimitCL
13 NFCs submitted Dynamic Modelling outputs:
Austria, Bulgaria, Switzerland, Czech Republic, Germany, France, Great Britain, Ireland, Italy, Norway, Luxembourg, Poland, Sweden.
Countries now into integrated regional dynamic modelling
What are the model predictions?
• Recovery does not reverse the path of acidification
• Fast effect initially, very slow final recovery
• Recovery is not 100%
Prediction: Lake pH in Scandinavia
7.0
6.5
6.0
5.5
5.0
4.5
4.01850 1880 1910 1940 1970 2000 2030 2060
Svagt buffrat
Starkare buffrat
Median
Simulerat pH-värde i avrinningen
Dynamic simulations:Soil pH in
the long runin Sweden
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are needed to see this picture.
But BC/Al what we work
with
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are needed to see this picture.
Soil base saturation, lost ?
0
10
20
30
40
50
1850 1900 1950 2000 2050
NorrMellansverigeSydväst
Markens basmättnadsgrad (%)
Simple messages to policy?
• Critical load (CL)– No significant harmful effects if deposition
don’t exceed CL
• Target load (TL)– Recovery by specified year if deposition don’t
exceed TL
Interpretation of target loads
Will not recover by
2030
Will recover by 2030
TLmax(S)-2030 5th percentile CLmax(S)
20 years with critical loads
• 1968 Acidification put on the official agenda by Prof Svante Oden in Uppsala
• 1979 Convention on long range transboundary air pollution
• 1985 First Olso protocol on flat rate 30% sulfur emission reduction
• 1990 The second Oslo protocol, effects based but settling on 60% sulfur emission reduction
• 1999 The Göteborg protocol, effects based settling for -85% S/-30% NOx
• 2010 revision of the Göteborg effects based protocol
Conclusions
International efforts to prevent acidification have been very successful
Critical oads very extremely successful in linking environmental goals through science to policy
Acidification remains as a large and significant problem in large areas of Europe
