why should we care about greenland watersheds? reactions ... · reactions, runoff, and rising sea...
TRANSCRIPT
![Page 1: Why should we care about Greenland watersheds? Reactions ... · Reactions, runoff, and rising sea level Jon Martin Ellen Martin Cecilia Scribner Kelly Deuerling Daniel Collazo Adam](https://reader034.vdocuments.site/reader034/viewer/2022042909/5f3cf9c15dbdcf0bb864d2c5/html5/thumbnails/1.jpg)
Why should we care about Greenland watersheds?
Reactions, runoff, and rising sea level
Jon Martin Ellen Martin Cecilia Scribner Kelly Deuerling Daniel Collazo Adam Marshall
![Page 2: Why should we care about Greenland watersheds? Reactions ... · Reactions, runoff, and rising sea level Jon Martin Ellen Martin Cecilia Scribner Kelly Deuerling Daniel Collazo Adam](https://reader034.vdocuments.site/reader034/viewer/2022042909/5f3cf9c15dbdcf0bb864d2c5/html5/thumbnails/2.jpg)
Subglacial Deglacial
Proglacial Water system under the ice
Melt water discharged from the ice sheet
Water from annual precipitation and permafrost melt
Modified from Anderson, 2007, Ann. Rev. Earth Planet Sci
Greenland Watersheds
Subglacial
Proglacial Deglacial
![Page 3: Why should we care about Greenland watersheds? Reactions ... · Reactions, runoff, and rising sea level Jon Martin Ellen Martin Cecilia Scribner Kelly Deuerling Daniel Collazo Adam](https://reader034.vdocuments.site/reader034/viewer/2022042909/5f3cf9c15dbdcf0bb864d2c5/html5/thumbnails/3.jpg)
Significance: Watershed Variations
~20ky
Last Glacial Maximum All sub- & pro-glacial Much fresh material
Now Mostly deglacial
Much weathered material
![Page 4: Why should we care about Greenland watersheds? Reactions ... · Reactions, runoff, and rising sea level Jon Martin Ellen Martin Cecilia Scribner Kelly Deuerling Daniel Collazo Adam](https://reader034.vdocuments.site/reader034/viewer/2022042909/5f3cf9c15dbdcf0bb864d2c5/html5/thumbnails/4.jpg)
Implication 1: Sea level rise
• Spectacular events: – (MWP1A) 14.5 – 14.0 ka
BP > 40 mm/yr
– Reflect rapid collapse of continental ice sheets
• Change in the material fluxes: – To ocean: isotopes &
nutrients (?)
– With atmosphere: CO2
Lambeck et al., 2014, PNAS Forward in time
![Page 5: Why should we care about Greenland watersheds? Reactions ... · Reactions, runoff, and rising sea level Jon Martin Ellen Martin Cecilia Scribner Kelly Deuerling Daniel Collazo Adam](https://reader034.vdocuments.site/reader034/viewer/2022042909/5f3cf9c15dbdcf0bb864d2c5/html5/thumbnails/5.jpg)
Implication 2: Runoff (and fluxes)
• Systematic shifts in Pb isotopes in North Atlantic sediments: – Rapid increase during
rapid SL rise
– Gradual drift down following SL rise
• Reflect changes in runoff composition (reactions)
Lambeck et al., 2014, PNAS; Gutjahr et al., 2009, EPSL; Kurzweil et al., 2010, EPSL; Crocket et al., 2012
Sea
leve
l
Orphan knoll
Laurentian Fan
Blake Ridge
![Page 6: Why should we care about Greenland watersheds? Reactions ... · Reactions, runoff, and rising sea level Jon Martin Ellen Martin Cecilia Scribner Kelly Deuerling Daniel Collazo Adam](https://reader034.vdocuments.site/reader034/viewer/2022042909/5f3cf9c15dbdcf0bb864d2c5/html5/thumbnails/6.jpg)
Implications 3: Reactions
Upper: Harlavan et al., 1998, GCA; Lower: Blum and Erel, 1997, GCA
Large D values
Large D values
Small D values
Small D values
• Offset between whole rock and leached material – Represent weathering
products
• Offset increases with younger material
• Causes: – Change in minerals being
weathered (Sr) – Availability of radiogenic
isotopes in damaged crystal lattices (Pb)
![Page 7: Why should we care about Greenland watersheds? Reactions ... · Reactions, runoff, and rising sea level Jon Martin Ellen Martin Cecilia Scribner Kelly Deuerling Daniel Collazo Adam](https://reader034.vdocuments.site/reader034/viewer/2022042909/5f3cf9c15dbdcf0bb864d2c5/html5/thumbnails/7.jpg)
Subglacial
Deglacial Proglacial
c Modified from Anderson, 2007
Kurzweil et al. , 2010
• Hypothesis 1:
• Weathering
extent/products
should vary across
watershed types
• Hypothesis 2:
• Solutes in addition to
Pb should vary with
runoff
Hypotheses
Laurentian Fan, North Atlantic
![Page 8: Why should we care about Greenland watersheds? Reactions ... · Reactions, runoff, and rising sea level Jon Martin Ellen Martin Cecilia Scribner Kelly Deuerling Daniel Collazo Adam](https://reader034.vdocuments.site/reader034/viewer/2022042909/5f3cf9c15dbdcf0bb864d2c5/html5/thumbnails/8.jpg)
Field Areas for Tests
50 km
Kangerlussuaq
Sisimiut Nerumaq
Qorlortoq
Google Earth
Lake Helen
500 km
~9.9 ky ~9.2 ky
~8.5 ky
~7.3 ky + water – balance
~125 km transect coast to GrIS • Similar lithologies (Nagssugtoqidian) • Gradient in exposure age of moraines • Gradient in precipitation vs. evaporation
~6.8 ky
Google Earth
![Page 9: Why should we care about Greenland watersheds? Reactions ... · Reactions, runoff, and rising sea level Jon Martin Ellen Martin Cecilia Scribner Kelly Deuerling Daniel Collazo Adam](https://reader034.vdocuments.site/reader034/viewer/2022042909/5f3cf9c15dbdcf0bb864d2c5/html5/thumbnails/9.jpg)
Two types deglacial watersheds
Coastal, wet, older moraines; More congruent weathering? (cool colors upcoming figures)
Inland, dry, younger moraines; Less congruent weathering? (warm colors upcoming figures)
![Page 10: Why should we care about Greenland watersheds? Reactions ... · Reactions, runoff, and rising sea level Jon Martin Ellen Martin Cecilia Scribner Kelly Deuerling Daniel Collazo Adam](https://reader034.vdocuments.site/reader034/viewer/2022042909/5f3cf9c15dbdcf0bb864d2c5/html5/thumbnails/10.jpg)
One proglacial watershed
• Watson River (Akuliarusiarsuup Kuua) • Does hyporheic exchange affect weathering?
• Sampled 4 times over 2 years • Including pore waters
![Page 11: Why should we care about Greenland watersheds? Reactions ... · Reactions, runoff, and rising sea level Jon Martin Ellen Martin Cecilia Scribner Kelly Deuerling Daniel Collazo Adam](https://reader034.vdocuments.site/reader034/viewer/2022042909/5f3cf9c15dbdcf0bb864d2c5/html5/thumbnails/11.jpg)
Melt season: Watson River to Kangerlussuaq fjord
![Page 12: Why should we care about Greenland watersheds? Reactions ... · Reactions, runoff, and rising sea level Jon Martin Ellen Martin Cecilia Scribner Kelly Deuerling Daniel Collazo Adam](https://reader034.vdocuments.site/reader034/viewer/2022042909/5f3cf9c15dbdcf0bb864d2c5/html5/thumbnails/12.jpg)
Melt season: Watson River vs Tractor
![Page 13: Why should we care about Greenland watersheds? Reactions ... · Reactions, runoff, and rising sea level Jon Martin Ellen Martin Cecilia Scribner Kelly Deuerling Daniel Collazo Adam](https://reader034.vdocuments.site/reader034/viewer/2022042909/5f3cf9c15dbdcf0bb864d2c5/html5/thumbnails/13.jpg)
Discharge: Proglacial vs Deglacial
• Watersheds of western Greenland • Similar amounts of discharge from deglacial and Greenland ice sheet • Is composition different within deglacial watersheds?
Mernild et al., 2010, The Cryosphere
![Page 14: Why should we care about Greenland watersheds? Reactions ... · Reactions, runoff, and rising sea level Jon Martin Ellen Martin Cecilia Scribner Kelly Deuerling Daniel Collazo Adam](https://reader034.vdocuments.site/reader034/viewer/2022042909/5f3cf9c15dbdcf0bb864d2c5/html5/thumbnails/14.jpg)
Na vs. Cl
coastal
inland
Waters
Seawater molar ratio
Excess Na in coastal watersheds Likely source- plagioclase (NaAlSi3O8) weathering
Scribner et al., 2015, GCA
![Page 15: Why should we care about Greenland watersheds? Reactions ... · Reactions, runoff, and rising sea level Jon Martin Ellen Martin Cecilia Scribner Kelly Deuerling Daniel Collazo Adam](https://reader034.vdocuments.site/reader034/viewer/2022042909/5f3cf9c15dbdcf0bb864d2c5/html5/thumbnails/15.jpg)
Major Cations and Anions
coastal
inland
coastal
inland
Wimpenny et al., 2010
Ryu and Jacobson, 2014 Meybeck, 1987
Water Samples
Scribner et al., 2015, GCA
Major cations- Ca Si higher in coastal watersheds Transition from carbonate alkalinity to SO4
![Page 16: Why should we care about Greenland watersheds? Reactions ... · Reactions, runoff, and rising sea level Jon Martin Ellen Martin Cecilia Scribner Kelly Deuerling Daniel Collazo Adam](https://reader034.vdocuments.site/reader034/viewer/2022042909/5f3cf9c15dbdcf0bb864d2c5/html5/thumbnails/16.jpg)
Waters vs. Bedload
Nerumaq Sisimiut
Qorlortoq
Lake Helen
Waters
Coastal waters = higher Na+K, Si Coastal bedload = lower Na+K, Si
Bedload and Moraines
![Page 17: Why should we care about Greenland watersheds? Reactions ... · Reactions, runoff, and rising sea level Jon Martin Ellen Martin Cecilia Scribner Kelly Deuerling Daniel Collazo Adam](https://reader034.vdocuments.site/reader034/viewer/2022042909/5f3cf9c15dbdcf0bb864d2c5/html5/thumbnails/17.jpg)
Weathered Minerals
• Inland deglacial – carbonate, little silicate • Coast deglacial & Proglacial – increased silicate • Coastal – sulfide • Proglacial – increased biotite over subglacial
![Page 18: Why should we care about Greenland watersheds? Reactions ... · Reactions, runoff, and rising sea level Jon Martin Ellen Martin Cecilia Scribner Kelly Deuerling Daniel Collazo Adam](https://reader034.vdocuments.site/reader034/viewer/2022042909/5f3cf9c15dbdcf0bb864d2c5/html5/thumbnails/18.jpg)
D87Sr/86Sr
• Small D87Sr/86Sr ratio reflects more congruent weathering • Large D87Sr/86Sr ratio reflects less congruent weathering • Surprise that 7 ky old moraines have incongruent weathering –
reflects little precipitation
Scribner et al., 2015, GCA
![Page 19: Why should we care about Greenland watersheds? Reactions ... · Reactions, runoff, and rising sea level Jon Martin Ellen Martin Cecilia Scribner Kelly Deuerling Daniel Collazo Adam](https://reader034.vdocuments.site/reader034/viewer/2022042909/5f3cf9c15dbdcf0bb864d2c5/html5/thumbnails/19.jpg)
Quick summary - deglacial
• Weathering extent increases toward coast
– More silica and sulfide, less carbonate
– Less biotite weathering
– More congruent Sr isotope ratios
• Causes:
– Longer exposure times - but not that different (3ky)
– Precipitation greater – likely largest cause
![Page 20: Why should we care about Greenland watersheds? Reactions ... · Reactions, runoff, and rising sea level Jon Martin Ellen Martin Cecilia Scribner Kelly Deuerling Daniel Collazo Adam](https://reader034.vdocuments.site/reader034/viewer/2022042909/5f3cf9c15dbdcf0bb864d2c5/html5/thumbnails/20.jpg)
Proglacial Watson River • Two sandur sites
– Large glacial outwash plains
• Hyporheic exchange & weathering?
![Page 21: Why should we care about Greenland watersheds? Reactions ... · Reactions, runoff, and rising sea level Jon Martin Ellen Martin Cecilia Scribner Kelly Deuerling Daniel Collazo Adam](https://reader034.vdocuments.site/reader034/viewer/2022042909/5f3cf9c15dbdcf0bb864d2c5/html5/thumbnails/21.jpg)
• Watson River – Time lapse photography; 9 pm to 9 am
Thanks to Mike Davlantes
![Page 22: Why should we care about Greenland watersheds? Reactions ... · Reactions, runoff, and rising sea level Jon Martin Ellen Martin Cecilia Scribner Kelly Deuerling Daniel Collazo Adam](https://reader034.vdocuments.site/reader034/viewer/2022042909/5f3cf9c15dbdcf0bb864d2c5/html5/thumbnails/22.jpg)
Head and chemistry measurements
• Sample pore water
– “vapor probe”
• What reactions occur?
• What is exchange?
– Piezometer – measure K
• Transect of
piezometers
• Instrumented with CTDs
Deuerling et al., in prep.
River elevation variations
![Page 23: Why should we care about Greenland watersheds? Reactions ... · Reactions, runoff, and rising sea level Jon Martin Ellen Martin Cecilia Scribner Kelly Deuerling Daniel Collazo Adam](https://reader034.vdocuments.site/reader034/viewer/2022042909/5f3cf9c15dbdcf0bb864d2c5/html5/thumbnails/23.jpg)
Head Gradients and Flow Direction
• Distal Site:
– Gradients oriented toward bank
• Proximal site:
– Diel alterations
• Sampling time:
– Increasing melt
– Increasing stream stage
Gradient toward bank
Gradient toward river
Deuerling et al., in prep.
K = 10-4 TO 10-5 m/sec
![Page 24: Why should we care about Greenland watersheds? Reactions ... · Reactions, runoff, and rising sea level Jon Martin Ellen Martin Cecilia Scribner Kelly Deuerling Daniel Collazo Adam](https://reader034.vdocuments.site/reader034/viewer/2022042909/5f3cf9c15dbdcf0bb864d2c5/html5/thumbnails/24.jpg)
Pore water composition
• Decrease pH:
– Sulfide oxidation
– Atmospheric CO2
Range of Watson River water
Pore Water
• Correlation reflects gypsum reaction – Cryogenic
concentration – Subsequent
dissolution
Gypsum line
![Page 25: Why should we care about Greenland watersheds? Reactions ... · Reactions, runoff, and rising sea level Jon Martin Ellen Martin Cecilia Scribner Kelly Deuerling Daniel Collazo Adam](https://reader034.vdocuments.site/reader034/viewer/2022042909/5f3cf9c15dbdcf0bb864d2c5/html5/thumbnails/25.jpg)
Summary - proglacial
• Early and late melt season
• Discharge from banks
• Peak melt season
– Diurnal variations
• Recharge to banks
Deuerling et al., in prep.
• Dissolution of primary and secondary minerals
![Page 26: Why should we care about Greenland watersheds? Reactions ... · Reactions, runoff, and rising sea level Jon Martin Ellen Martin Cecilia Scribner Kelly Deuerling Daniel Collazo Adam](https://reader034.vdocuments.site/reader034/viewer/2022042909/5f3cf9c15dbdcf0bb864d2c5/html5/thumbnails/26.jpg)
Conclusions
• Distinctly different weathering process
• Between subglacial, proglacial, and deglacial watersheds
• Across deglacial watersheds
• Exchange in sandurs important weathering sites in proglacial systems
• Muskox pizzas are actually quite tasty
![Page 27: Why should we care about Greenland watersheds? Reactions ... · Reactions, runoff, and rising sea level Jon Martin Ellen Martin Cecilia Scribner Kelly Deuerling Daniel Collazo Adam](https://reader034.vdocuments.site/reader034/viewer/2022042909/5f3cf9c15dbdcf0bb864d2c5/html5/thumbnails/27.jpg)
Implications
• Retreat of ice sheets:
– Increase deglacial fluxes
– Area of intense weathering expands
• Will alter/has altered elemental, nutrient(?), CO2(?) and isotopic fluxes
– Use proxies for interpreting past changes
– Predict future changes Non-edible wildlife
annoying, but not so dangerous
![Page 28: Why should we care about Greenland watersheds? Reactions ... · Reactions, runoff, and rising sea level Jon Martin Ellen Martin Cecilia Scribner Kelly Deuerling Daniel Collazo Adam](https://reader034.vdocuments.site/reader034/viewer/2022042909/5f3cf9c15dbdcf0bb864d2c5/html5/thumbnails/28.jpg)
Future Directions
• Expand field sites – Narsarsuaq > 2000 mm
precipitation – 1.6 ky moraines
• Evaluate fluxes • Expand mineral
reactions – Nutrients (P, Fe, C) – OC lability changes
Oceanic fluxes
Synthesis
Outputs
Observations
Water and solid concentrations and
radiogenic isotope (Pb, Sr) ratios
Nutrient (Fe, P) concentrations,
reactions, and sources
Organic carbon lability; water-atmosphere CO2
exchange
Mineral dissolution & precipitation
Fe and P production & sequestration
Organic carbon
oxidation
Weathering Deglacial vs Proglacial
Atmospheric fluxes
![Page 29: Why should we care about Greenland watersheds? Reactions ... · Reactions, runoff, and rising sea level Jon Martin Ellen Martin Cecilia Scribner Kelly Deuerling Daniel Collazo Adam](https://reader034.vdocuments.site/reader034/viewer/2022042909/5f3cf9c15dbdcf0bb864d2c5/html5/thumbnails/29.jpg)
??? Questions
???
![Page 30: Why should we care about Greenland watersheds? Reactions ... · Reactions, runoff, and rising sea level Jon Martin Ellen Martin Cecilia Scribner Kelly Deuerling Daniel Collazo Adam](https://reader034.vdocuments.site/reader034/viewer/2022042909/5f3cf9c15dbdcf0bb864d2c5/html5/thumbnails/30.jpg)
East AAIS (52 m)
Gainesville (your house) elevation ~20-30 masl
West AAIS (5 m)
Greenland IS (7m)
Modern Sea level
Continental ice sheets and sea level
Graphics thanks to E. Martin
![Page 31: Why should we care about Greenland watersheds? Reactions ... · Reactions, runoff, and rising sea level Jon Martin Ellen Martin Cecilia Scribner Kelly Deuerling Daniel Collazo Adam](https://reader034.vdocuments.site/reader034/viewer/2022042909/5f3cf9c15dbdcf0bb864d2c5/html5/thumbnails/31.jpg)
Measured sea level records
IPCC, 2013 5th AR
• Satellite-based altimetry – compilation 5 groups
• Increase very likely 3.2 mm/yr 1993-2012
• Longer term records - Salt marshes, tide gauges, altimetry
• Tide gauge increase very likely 1.7 mm/yr 1901 - 2001
Decadal Centennial
![Page 32: Why should we care about Greenland watersheds? Reactions ... · Reactions, runoff, and rising sea level Jon Martin Ellen Martin Cecilia Scribner Kelly Deuerling Daniel Collazo Adam](https://reader034.vdocuments.site/reader034/viewer/2022042909/5f3cf9c15dbdcf0bb864d2c5/html5/thumbnails/32.jpg)
Sea level projections
• Compilation of models • Projection of global mean
sea level for two extreme scenarios (RCP2.6 and RCP8.5 – process based)
• Thermal expansion greatest contributor (30-55%)
• Glacial melting (not Antarctica) second largest contributor (15 – 55%)
• Likely that rate of sea level rise will increase in 21st century – e.g., >3.2 mm/yr
IPCC, 2013 5th AR
![Page 33: Why should we care about Greenland watersheds? Reactions ... · Reactions, runoff, and rising sea level Jon Martin Ellen Martin Cecilia Scribner Kelly Deuerling Daniel Collazo Adam](https://reader034.vdocuments.site/reader034/viewer/2022042909/5f3cf9c15dbdcf0bb864d2c5/html5/thumbnails/33.jpg)
Greenland – a modern ice sheet • Model of surface mass balance
for 21st century
– Red – mass loss; blue – mass gain
• Equilibrium lines
– Purple now, Green 2100
• Insets: contribution to SL rise from outlet glaciers & ice sheet
• Question:
– How might weathering change as ice sheet retreats?
– Study transect in W Greenland
IPCC, 2013 5th AR
Study Transect
![Page 34: Why should we care about Greenland watersheds? Reactions ... · Reactions, runoff, and rising sea level Jon Martin Ellen Martin Cecilia Scribner Kelly Deuerling Daniel Collazo Adam](https://reader034.vdocuments.site/reader034/viewer/2022042909/5f3cf9c15dbdcf0bb864d2c5/html5/thumbnails/34.jpg)
Saturation states of watershed waters
• Feldspar minerals undersaturated
• Clays and oxides supersaturated Scribner et al., submitted, GCA
Dissolving
Precipitating ] Inland ] Coastal
![Page 35: Why should we care about Greenland watersheds? Reactions ... · Reactions, runoff, and rising sea level Jon Martin Ellen Martin Cecilia Scribner Kelly Deuerling Daniel Collazo Adam](https://reader034.vdocuments.site/reader034/viewer/2022042909/5f3cf9c15dbdcf0bb864d2c5/html5/thumbnails/35.jpg)
• Temporary piezometers (“vapor probe”)
• Sample pore waters for chemical compositions
![Page 36: Why should we care about Greenland watersheds? Reactions ... · Reactions, runoff, and rising sea level Jon Martin Ellen Martin Cecilia Scribner Kelly Deuerling Daniel Collazo Adam](https://reader034.vdocuments.site/reader034/viewer/2022042909/5f3cf9c15dbdcf0bb864d2c5/html5/thumbnails/36.jpg)
Specific Conductivity vs depth
• Both locations show nearly order of magnitude increase in river over pore water
• Two possible causes – Cryogenic concentration
– Weathering
• Variations in elemental compositions indicate weathering important