"Planetary Grid - A New Synthesis" - William Becker & Bethe Hagens
Quantifying pH Dynamics in a Changing Ocean Mathilde Hagens & Jack Middelburg Earth Sciences Utrecht...
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Transcript of Quantifying pH Dynamics in a Changing Ocean Mathilde Hagens & Jack Middelburg Earth Sciences Utrecht...
![Page 1: Quantifying pH Dynamics in a Changing Ocean Mathilde Hagens & Jack Middelburg Earth Sciences Utrecht University.](https://reader033.fdocuments.in/reader033/viewer/2022051820/56649f015503460f94c16fed/html5/thumbnails/1.jpg)
Quantifying pH Dynamics in a Changing Ocean
Mathilde Hagens & Jack MiddelburgEarth Sciences
Utrecht University
![Page 2: Quantifying pH Dynamics in a Changing Ocean Mathilde Hagens & Jack Middelburg Earth Sciences Utrecht University.](https://reader033.fdocuments.in/reader033/viewer/2022051820/56649f015503460f94c16fed/html5/thumbnails/2.jpg)
Future Ocean
CO2 rich, Warmer and Low O2
• What are the consequences for ocean CO2 uptake?– Revelle factor: sensitivity of CO2 to DIC changes
• How will (seasonal and long-term) pH dynamics change?– Buffer factor: sensitivity of H+ to DIC and other
acid/base additions
![Page 3: Quantifying pH Dynamics in a Changing Ocean Mathilde Hagens & Jack Middelburg Earth Sciences Utrecht University.](https://reader033.fdocuments.in/reader033/viewer/2022051820/56649f015503460f94c16fed/html5/thumbnails/3.jpg)
pH = f (T, S, DIC, TA ….)
Total derivative of pH:
How to obtain the partial derivatives?• Numerically (small perturbations)• Analytically • Straightforward for DIC, but for TA …...
![Page 4: Quantifying pH Dynamics in a Changing Ocean Mathilde Hagens & Jack Middelburg Earth Sciences Utrecht University.](https://reader033.fdocuments.in/reader033/viewer/2022051820/56649f015503460f94c16fed/html5/thumbnails/4.jpg)
Partial derivative of TA
This buffer factor is based on the assumption that all but H+ remain constant
![Page 5: Quantifying pH Dynamics in a Changing Ocean Mathilde Hagens & Jack Middelburg Earth Sciences Utrecht University.](https://reader033.fdocuments.in/reader033/viewer/2022051820/56649f015503460f94c16fed/html5/thumbnails/5.jpg)
Sensitivity of TA to X
Buffer factor if all total concentrations are constant
Term for changes in total concentration of acid-base TotX
Term for changes in concentration of species X
where:
and
In the case of ocean acidification (X=H2CO3 and TotX=DIC):
![Page 6: Quantifying pH Dynamics in a Changing Ocean Mathilde Hagens & Jack Middelburg Earth Sciences Utrecht University.](https://reader033.fdocuments.in/reader033/viewer/2022051820/56649f015503460f94c16fed/html5/thumbnails/6.jpg)
Why this math?
• Generalised sensitivities:– Consistent with prior work by Frankignoulle (1994)
and Egleston et al. (2010)– All relevant acid-base systems
• Sensitivities:– project changes in pH dynamics– elucidate factors governing seasonal pH dynamics
• Similar approach applies to Revelle Factor
![Page 7: Quantifying pH Dynamics in a Changing Ocean Mathilde Hagens & Jack Middelburg Earth Sciences Utrecht University.](https://reader033.fdocuments.in/reader033/viewer/2022051820/56649f015503460f94c16fed/html5/thumbnails/7.jpg)
Revelle Factor extended
Revelle and Suess (1957)Sundquist et al. (1979)
• Includes all acid-base systems via partial derivative
• Consistent with prior work that included only carbon dioxide, borate and water dissociation
![Page 8: Quantifying pH Dynamics in a Changing Ocean Mathilde Hagens & Jack Middelburg Earth Sciences Utrecht University.](https://reader033.fdocuments.in/reader033/viewer/2022051820/56649f015503460f94c16fed/html5/thumbnails/8.jpg)
Sensitivity now and in 2100
Sensitivity Unit Present 2100 CO2
2100T
2100 CO2 + T
1601 2627 1517 2480
-1751 -2705 -1674 -2567
• Positive values: addition increases pH • Negative values: addition decreases pH• Ocean acidification increases sensitivity• Ocean warming lowers sensitivity
(mol kg-1)-1
(mol kg-1)-1
![Page 9: Quantifying pH Dynamics in a Changing Ocean Mathilde Hagens & Jack Middelburg Earth Sciences Utrecht University.](https://reader033.fdocuments.in/reader033/viewer/2022051820/56649f015503460f94c16fed/html5/thumbnails/9.jpg)
Projections
pH changes and gradients will increase CO2 uptake will decrease
![Page 10: Quantifying pH Dynamics in a Changing Ocean Mathilde Hagens & Jack Middelburg Earth Sciences Utrecht University.](https://reader033.fdocuments.in/reader033/viewer/2022051820/56649f015503460f94c16fed/html5/thumbnails/10.jpg)
Eutrophication and Ocean Acidification
![Page 11: Quantifying pH Dynamics in a Changing Ocean Mathilde Hagens & Jack Middelburg Earth Sciences Utrecht University.](https://reader033.fdocuments.in/reader033/viewer/2022051820/56649f015503460f94c16fed/html5/thumbnails/11.jpg)
What governs pH seasonality?
• Station ALOHA in the Pacific Ocean• Station DYFAMED in the Mediterranean Sea• Iceland Sea station in the North Atlantic
• Time series on pH, DIC, TA, T, S, borate, sulphate, fluoride, nutrients..
![Page 12: Quantifying pH Dynamics in a Changing Ocean Mathilde Hagens & Jack Middelburg Earth Sciences Utrecht University.](https://reader033.fdocuments.in/reader033/viewer/2022051820/56649f015503460f94c16fed/html5/thumbnails/12.jpg)
ALOHA
Harmonic least square fitPredicted using sensitivities
![Page 13: Quantifying pH Dynamics in a Changing Ocean Mathilde Hagens & Jack Middelburg Earth Sciences Utrecht University.](https://reader033.fdocuments.in/reader033/viewer/2022051820/56649f015503460f94c16fed/html5/thumbnails/13.jpg)
DYFAMED
Harmonic least square fitPredicted using sensitivities
![Page 14: Quantifying pH Dynamics in a Changing Ocean Mathilde Hagens & Jack Middelburg Earth Sciences Utrecht University.](https://reader033.fdocuments.in/reader033/viewer/2022051820/56649f015503460f94c16fed/html5/thumbnails/14.jpg)
Iceland Sea
Harmonic least square fitPredicted using sensitivities
![Page 15: Quantifying pH Dynamics in a Changing Ocean Mathilde Hagens & Jack Middelburg Earth Sciences Utrecht University.](https://reader033.fdocuments.in/reader033/viewer/2022051820/56649f015503460f94c16fed/html5/thumbnails/15.jpg)
Attribution of pH changes Temperature (T)Alkalinity (TA)Inorganic carbon (DIC)
Iceland SeaALOHADYFAMED
Winter pH: + T, - DICSummer pH: - T, + DIC
Winter pH: + T, - DICSummer pH: - T, + DIC
Complex pattern: T with DIC and TA
![Page 16: Quantifying pH Dynamics in a Changing Ocean Mathilde Hagens & Jack Middelburg Earth Sciences Utrecht University.](https://reader033.fdocuments.in/reader033/viewer/2022051820/56649f015503460f94c16fed/html5/thumbnails/16.jpg)
Seasonality in pH
• pH can be predicted
• TA, DIC and T most important
• T and DIC often compensate
Iceland
DyfamedBATS
Estoc
ALOHA
-0.2
-0.15
-0.1
-0.05
0
0.05
0.1
0.15
0.2
0.25
T
DIC
TA
pH a
mpl
itude
![Page 17: Quantifying pH Dynamics in a Changing Ocean Mathilde Hagens & Jack Middelburg Earth Sciences Utrecht University.](https://reader033.fdocuments.in/reader033/viewer/2022051820/56649f015503460f94c16fed/html5/thumbnails/17.jpg)
Thank you
• Generalised sensitivity factors • Extension to Revelle factor• Projections for future pH sensitivity• Understanding of pH seasonality
• Interested? PhD thesis “Impact of biogeochemical processes on pH dynamics in marine systems”
• http://dspace.library.uu.nl/handle/1874/313165.