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TRANSCRIPT
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Ecosystem effects of sulphur and nitrogen deposition in South Africa:
a view from Europe
Chris CurtisSchool of Geography, Archaeology &
Environmental Studies, Wits
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Effects of acid deposition:
Waldsterben
Source: Greenpeace
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Free-swimming mayfly Baetis rhodani
Acidification effects in aquatic ecosystems
Brown troutSalmo trutta
Typical softwater plantIsoetes lacustris
DipperCinclus cinclus
Photo:
Nigel Blake
Natterjack toadBufo calamita
Salmo trutta
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Critical loadsLinking chemical dose to biological response
Relationship betweenstatus of brown troutpopulations and ANC inNorwegian lakes
Source:Lien, L., Raddum, G.G. , Fjellheim, A.and Henriksen, A. (1996) A critical limitfor acid neutralizing capacity inNorwegian surface waters, based onnew analyses of fish and invertebrateresponses. Sci. Tot. Env. 177, 173-193.ANC is an “index” of acidification damage
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Total N dep (2008)from RoTAP (2012)
Critical load exceedance2004-06
not exceeded
2
Exceedancekeq ha-1 year-1
not exceeded
2
not exceeded
2
Exceedancekeq ha-1 year-1
http://www.rotap.ceh.ac.uk/
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Nitrate leaching and eutrophication
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Empirical critical loads for N
Bobbink & Hettelingh (2011) www.rivm/nl/cce
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Critical load exceedances for all ecosystems (2010 deposition)
http://www.emep.int/mscw/mscw_publications.html
EMEP (2012)http://www.emep.int/mscw/mscw_publications.html
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Sulphur deposition (mg/m2) in EuropeEMEP (2012)http://www.emep.int/mscw/mscw_publications.html
Europe is a region where deposition is decreasing drastically
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Fitted trends in xSO4 deposition at
1988
Source: RoTAP (2012)
Declining sulphur emissions, deposition and surface water sulphate in the UK, 1988-2008
Fitted trends in xSO4 inAWMN sites
Fitted trends in xSO4 deposition at selected ADMN sites
From Defra 20 year report
Curtis & Simpson (in press) Ecological Indicators
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eq ha-1a-1
no exceed.< 100100 - 200200 - 500500 - 800
Exceedance of CLs 1980
eq ha-1a-1
no exceed.< 100100 - 200200 - 500500 - 800
Exceedance of CLs GP 2020
Assessment of critical loads of acidity and their exceedances for European lakesCurtis et al. (in press 2013), Springer Environmental Pollution Series
500 - 800800 - 1200> 1200
Dep-data: EMEP/MSC-WCCE
500 - 800800 - 1200> 1200
Dep-data: EMEP/MSC-WCCE
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Average annual tropospheric NO2, 2005
Wenig et al. (2008) J. Geophys. Res. 113, D16S45
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Acidification in South Africa
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Van Tienhoven, A.M., Olbrich, K.A., Skoroszewski, R., Taljaard, J. & Zunckel, M. (1995) Application of the critical loads approach in South Africa. Water, Air & Soil
Pollution 85, 2577-2582.
Water chem not in paper but based on Skoroszewski RW (1995) Sensitivity of surface waters in the Eastern Transvaal Province. CSIR Report WM769.
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Net acid deposition in SA
Josipovic et al. (2011) Atmospheric dry and wet deposition of sulphur and nitrogen species and assessment of critical loads of acidic deposition exceedance in South Africa, South African Journal of Science, 107(3/4), Art. #478, 10 pages.
Soil Critical Load exceedance
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Acid sensitive waters in SA: upper headwaters & organic acidity
• Suikerbosrand (1992); pH 4.2-6.3 in ephemeral streams after heavy rain (Skoroszewski, RW, 1995, WASP 85: 2331-36)
• Van der Waal (1997) SAJ Aq Sci 23, 42-55; Lake Fundudzi (conifer forested Mutale River pH=5.3, swamp Fundudzi (conifer forested Mutale River pH=5.3, swamp pH 4.1)
• Grobbelaar, J.U. & Stegmann, P. (1987) Water SA 13(3), 151-158; 1970s data from Maluti Mountains, Lesotho –wetland springs (pH 5.3) and streams (pH 5.9) near Letsang la Terae diamond mine; rainfall mean 1975-76 pH of 5.2 (min 3.4)
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Verloren Valei Nature Reserve Ramsar wetland,
Mpumalanga
Some wetland streams have pH in range 5.9-6.3;in range 5.9-6.3;
potentially sensitive to acid
deposition
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Nitrogen deposition and Biodiversity in South AfricaBiodiversity in South Africa
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N Deposition in 2000 & 2030
Bleeker, A., Hicks, W.K., Dentener, F., Galloway, J. and Erisman, J.W., 2011: N deposition as a threat to the world’s protected areas under the Convention on Biological Diversity, Environmental Pollution, 159, 2280-88.
Deposition data from Dentener, F. et al. (2006) Nitrogen and sulfur deposition on regional and global scales: a multimodel evaluation. Global Biogeochemical Cycles 20, 21.
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Biodiversity hotspots
Bleeker et al., 2011
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Nitrogen depositionto biodiversity hotspots
Phoenix et al (2006)Global Change Biol.12, 470-76.
3: Cape Floristic Region19: Maputaland-Pondoland-Albany29: Succulent Karoo
29
3
19
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Mediterranean ecosystems
Critical loads of 3-17 kgN/ha/yr in California (Fenn et al., in press)
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N and vegetation
• Western Cape: background dep. c. 2 kgN/ha/yr (Stock & Lewis, 1986, SAJ. Bot. 52, 273-76)
• studies in Cape Metropolitan Area found increasing bryophyte tissue N content in herbarium samples suggesting increase of 6-13 kgN/ha/yrsince 1950 - could lead to critical load exceedance / biodiversity losses (Wilson, Stock & Hedderson, 2009, Env. Poll. 157, 938-45)(Wilson, Stock & Hedderson, 2009, Env. Poll. 157, 938-45)
• Collett et al. (2010) SAJS 106 (5/6) Art.~220; Highveld atmos. nitrogen Ndep 6.7-13.1 kgN/ha/yr
Josipovic et al. (2010) Concentrations, distributions and critical level exceedance assessment of SO2, NO2 and O3 in South Africa. Environ. Monit. Assess. 171, 181-96• CLs for lichens exceeded at 3 Highveld sites and at Elandsfontein only
for forests/semi-natural vegetation
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Conclusions1. Unlike Europe, acid deposition is increasing in parts of South Africa2. Deposition loads on Highveld comparable to loads causing acidification of
European soils and waters3. Acidification may be occurring in parts of SA but is probably a highly
localised problem since most of the country is not acid-sensitive4. Nitrogen deposition may be a more insidious and widespread threat than 4. Nitrogen deposition may be a more insidious and widespread threat than
acidification5. N deposition loads on Highveld and in Cape Metropolitan Area are higher
than those found to affect terrestrial vegetation (including Mediterranean types) and surface waters in the northern hemisphere
6. Better data required on national distribution of deposition for both S and N7. Need to investigate the sensitivity of biota to acidity and nutrient nitrogen
effects
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Ecosystem effects of sulphur and nitrogen deposition in South Africa: a view from Europe
Chris Curtis, School of Geography, Archaeology & Environmental Studies
KEY QUESTIONS• What is the distribution of wet and dry S and N deposition across South Africa?AcidificationAcidification• How much is known about dose-response functions for acidity and South African biota?
(i.e. are there acid-sensitive species of fish, inverts etc.)?• What is the national distribution of acid sensitive waters? (soils, geology)• Where are critical loads being exceeded at present and in the future?Nutrient N• What are effects of N on sensitive biota? (algae, lichens, higher plants)• Can deposition be an important part of N budgets in certain ecosystems?• What are implications for biogeochemical cycles of excess N deposition? (carbon
sequestration in forests, wetlands; denitrification)
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Site June July September
Scoat Tarn P P P
Small Water Co Co Co
Burnmoor Tarn Co N Co
Llyn Edno Co P P
Llyn Gamallt Fawr Co Co N
Llyn Hiraethlyn N N Co
Lochnagar
Eutrophication threat from N deposition
Llyn Hiraethlyn N N Co
Llyn Mair Co P Co
Hammer Pond N Co N
Loch Beanie Co P P
Lochnagar Co P P
Loch Coire nan Eion Co Co P
Loch Coire Fhionnaraich Co N Co
Loch Coire Mhic Fhearchair
Co P P
a) b)
c) d)
Periphytometer testing atRiver Etherow Phytoplankton N and P limitation bioassays
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The nitrogen issue: global concern
The Nitrogen Cascade: Galloway et al. (2003), BioScience 53, 341-356.
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Future N Deposition
Bleeker et al., 2011