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)
Kari Austnes and 4-5 November 2017 1 Chris Curtis Background and objectives Scorgie & Kornelius (2009) • 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 • 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
Kari Austnes and 4-5 November 2017 2 Christopher Curtis
Data collection
• 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
Kari Austnes and 4-5 November 2017 3 Christopher Curtis Deposition
• Clear gradient • Highest S and N dep comparable to upper range of dep observed in Europe
kg/ha kg/ha kg/ha
1000 20 500 10 200 5 100 2 50 1 20 0.5 10 0.2 5 0.1 2 0.05
Kari Austnes and 4-5 November 2017 4 Christopher Curtis Stream chemistry
Waterberg
WB06 SW Cape
Kari Austnes and 4-5 November 2017 5 Chris Curtis Critical loads: defining harmful effects
Threshold: “Waterberg barb” ANC<20 µeq/L
Waterberg: 4 (10%) SW Cape: 21 (70%)
Kari Austnes and 4-5 November 2017 6 Chris Curtis 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 • 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 Hindar and Wright (2005), deposition if we want to avoid example MAGIC simulation surface water acidification?
Kari Austnes and 4-5 November 2017 7 Chris Curtis 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)
Kari Austnes and 4-5 November 2017 8 Chris Curtis 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)
Kari Austnes and 4-5 November 2017 9 Chris Curtis