Post on 16-Oct-2021
Kari Austnes and Chris Curtis
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Acid deposition and acidification of waters in South Africa: status and prognoses given future climate change (AcidWater)
SANCOOP Concluding Conference Nov 2017
Project partners: The Norwegian Institute for Water Research (NIVA), University of the Witwatersrand (Wits), North-West University (NWU), The Norwegian Institute for Air Research (NILU)
4-5 November 2017
Background and objectives
• Increasing emissions of sulphur and nitrogen
– Primarily from coal-fired power plants
– Acid deposition → acidification of surface water in sensitive areas →
harmful effects to aquatic biota
– Little known about extent and severity
4-5 November 2017 Kari Austnes and
Christopher Curtis 2
• Primary objective
– Collect new high-quality data for acid deposition and chemistry and biology of potentially acid-sensitive streams in South Africa
• Secondary objectives
– Estimate critical loads of acidity for streams
– Assess the effect of future scenarios of climate change and acid deposition on the ecological status of streams
Scorgie &
Kornelius
(2009)
Data collection
4-5 November 2017 Kari Austnes and
Christopher Curtis 3
• Three study regions
– Range in deposition
– One deposition station per region
– 30-40 streams per region (20-30 key streams)
– Water chemistry and benthic invertebrates
– 4 times per year (2 for invertebrates)
– 450 water samples, 125 inverts samples
4-5 November 2017 Kari Austnes and
Christopher Curtis
Deposition
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1000 500 200 100 50 20 10 5 2
kg/ha
20 10 5 2 1 0.5 0.2 0.1 0.05
kg/ha kg/ha
• Clear gradient
• Highest S and N dep comparable to upper range of dep observed in Europe
Stream chemistry
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Chris Curtis 5
WB06
Waterberg
SW Cape
Critical loads: defining harmful effects
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Chris Curtis 6
“Waterberg barb” Threshold:
ANC<20 µeq/L
Waterberg: 4 (10%)
SW Cape: 21 (70%)
Future threats: air pollution and climate change
• Modelling future water chemistry using the MAGIC model
– Dynamic process-oriented biogeochemical model
– Using deposition and climate scenarios
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Chris Curtis 7
Hindar and Wright (2005), example MAGIC simulation
• Questions to address
– For how long can the soils buffer against the predicted increasing deposition?
– Will climate change exacerbate the effects of acid deposition?
– What is the maximum allowable deposition if we want to avoid surface water acidification?
Students and research
• Londiwe Khuzwayo (Wits, PhD)
• Mpho Mompati (NWU, MSc)
• Erasmus de Wet (NWU, MSc)
• Fulufhelo Makhani (Wits, Honours)
• Khuliso Muleka (Wits, Honours)
Affiliated studies:
• Aobakwe Lenkwe (Wits, MSc – ACCESS student working at Cathedral Peak, using deposition data)
• Isabel Mbewe (Wits, MSc –Highveld streams and deposition)
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Chris Curtis 8
Policy and the public
• Waterberg-Bojanala & Highveld Priority Areas (DEA)
• Waterberg Biosphere Reserve, Marakele National Park, Garden Route National Park, Maloti-Drakensberg Transboundary World Heritage Site
• NACA National Conference 2016 (SASOL/Eskom Workshop: Atmos. Dep. Studies in SA) & 2017
• NRF Global Change 2014 & 2016
• Acid Rain 2015 (USA); BIOGEOMON 2017 (Czech Republic)
• DEA State of the Air Report 2017 (Acid Deposition)
4-5 November 2017 Kari Austnes and
Chris Curtis 9