canadian accomplishments on critical load mapping
DESCRIPTION
Canadian accomplishments on Critical Load Mapping. Surface waters Dean Jeffries, EC, ON Jacques Dupont, MENV, QC Jill Franklyn, EC, ON David Lam, EC, ON Fred Norouzian, EC, ON Isaac Wong, EC, ON. Forests Rock Ouimet, MRNFP, QC Paul A. Arp, UNB, N.B. Shaun Watmough, TU, ON - PowerPoint PPT PresentationTRANSCRIPT
Riverside CL meeting, Feb. 15-18, 2005
Canadian accomplishmentson Critical Load Mapping
Forests
Rock Ouimet, MRNFP, QC
Paul A. Arp, UNB, N.B.
Shaun Watmough, TU, ON
Julian Aherne, TU, ON
Ian DeMerchant, NRCan, N.B.
Surface waters
Dean Jeffries, EC, ON
Jacques Dupont, MENV, QC
Jill Franklyn, EC, ON
David Lam, EC, ON
Fred Norouzian, EC, ON
Isaac Wong, EC, ON
2Riverside CL meeting, Feb. 16-18, 2005
Canadian Accomplishments on Critical Loads
History Definitions Chemical thresholds and methods
Aquatic Terrestrial
Critical loads and exceedances Aquatic Terrestrial
Combined critical loads and exceedances Uncertainties
3Riverside CL meeting, Feb. 16-18, 2005
History, definitions
1983 Target load: 20 kg/ha/yr wet SO42- deposition
1990 8 < S-CL > 20 kg/ha/yr NSS-wet SO42- deposition
1997 Aquatic (6 < S-CL > 18 kg/ha/yr)Terrestrial (90 < S&N-CL < 2900 eq/ha/yr)
1998 NEG/ECP initiative
2005 EC report on acid deposition science assessmentFirst mapping of terrestrial CL for eastern CanadaUpdated mapping of aquatic CL for eastern and first
mapping of CL for western Canada
4Riverside CL meeting, Feb. 16-18, 2005
Definitions
Critical load « The highest deposition of acidifying compounds that will not
cause chemical changes leading to long-term harmful effects on ecosystem structure and functions »
Nilsson and Grennfelt (1988)
« A quantitative estimate of an exposure to one or more pollutants below which significant harmful effects on specified elements do not occur according to present knowledge »
UN ECE (1994)
« A quantitative estimate of an exposure to one or more pollutants below which the probability of long-term unacceptable effects on specified elements is acceptable according to present knowledge and policy »
Barkman (1998)
5Riverside CL meeting, Feb. 16-18, 2005
Chemical thresholds and methods : the steady-state approach
Aquatic Biotic toxicity of the lower aquatic food web Acid neutralizing Capacity (ANC) = 40 µeq/L (~pH = 6.0) Model : Expert (Lam et al. 1994) SSWC (Henriksen & Posch 2001)
Terrestrial Maintaining current soil base saturation of forest soils Log(KGibb) = 9.0 BC/Al = 10 (M/M) The Simple Mass-Balance Model (SMB)
Critical load
limitUptakeWeatheringDepositionAcidity ANCBCBCBCCL
6Riverside CL meeting, Feb. 16-18, 2005
Critical loads and exceedances Aquatic CL
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Critical loads and exceedances Aquatic CL Exceedance
8Riverside CL meeting, Feb. 16-18, 2005
Critical loads and exceedances Terrestrial CL (no harvesting, no forest fire)
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Critical loads and exceedances Terrestrial CL Exceedance
10Riverside CL meeting, Feb. 16-18, 2005
Combined critical load
11Riverside CL meeting, Feb. 16-18, 2005
Combined critical load exceedances
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Uncertainties
Assumptions Steady state
Methodological, technical, epistemological
There is a potential for reducing uncertainties
Critical loads : an environmental risk assessment for international and domestic policy development
The complete report of the
Canadian Acid Deposition Science Assessment
is available next week at
http://www.msc-smc.ec.gc.ca/saib/acid/acid_e.html
13Riverside CL meeting, Feb. 16-18, 2005
Terrestrial critical loads