3J-05 Proposed acidification indicators for the Baltic Sea Bo - - PowerPoint PPT Presentation

Rehder, Carstensen, Gustafsson HELCOM S&C, May 2018

Proposed acidification indicators for the Baltic Sea

3J-05 – Proposed acidification indicators for the Baltic Sea

Bo Gustafsson Gregor Rehder Jacob Carstensen

Rehder, Carstensen, Gustafsson HELCOM S&C, May 2018

Proposed acidification indicators for the Baltic Sea

Introductory Thoughts

MSFD Proton activity (or concentration) is per se the most direct acidification indicator

• Basically governed by the

inorganic carbon system Carbon as eutrophication key variable

• Nixon et al., 1995

Carbon is the most direct link between productivity and O2- consumption

2 MSFD, Annex III (Indicative lists of characteristics, pressures and impacts), table I, physical and chemical features: „Profiles of pH and pCO2 or similar information to measure marine acidification“

pH = - log aH+ pHT = -log ([H+] + [HSO4

• ]).

Eutrophication: “An increase in the rate of supply of organic matter to an ecosystem“

106CO2 + 16NO3

• + HPO4

2- +

122H2O + 18 H+ → (CH2O)106(NH3)16 (H3PO4) + 138O2∙

Rehder, Carstensen, Gustafsson HELCOM S&C, May 2018

Proposed acidification indicators for the Baltic Sea

3 CO2 H2CO3 H+ + HCO3

−

HCO3

−

Ca2++ CO3

2− Ω = Ca2+ ∙ [CO3

2−]

KL

CaCO3

Weathering Biogenic calcification

Strict linkage relies on constant alkalinity pCO2: +1.6 µatm yr-1 pHT: -0.0016 yr-1

2 From Doney et al., 2009

Rehder, Carstensen, Gustafsson HELCOM S&C, May 2018

Proposed acidification indicators for the Baltic Sea

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Carbon dioxide system

– CT

• Method readily established, very few measurements in the Baltic Sea
• No brackish water limitations

– AT

• Measured since a century, large improvement of data quality in the last 25 years
• Baltic Sea: Non negligible contribution from organic alkalinity, trends on decadal scale

– pCO2

• Mainly surface water applications
• Not included in HELCOM monitoring manual, but established SOPs (SOCAT)
• No brackish water limitations

– pH

• Inherent problem in potentiometric measurements
• Spectrophotometry so far only state-of-the-art method for open ocean conditions
• In HELCOM monitoring as “side parameter”

Rehder, Carstensen, Gustafsson HELCOM S&C, May 2018

Proposed acidification indicators for the Baltic Sea

From global to local

5

Rehder, Carstensen, Gustafsson HELCOM S&C, May 2018

Proposed acidification indicators for the Baltic Sea

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1995 - 2014 Rate: +3.4 µmol kg-1 yr-1 Relative Change: +5%

• Comp. North Atlantic: +0.1%

Introduction of reference materials! AT-increase

• mitigates acidificiation

through CO2-uptake!

• Increases potential CO2-

uptake

A

T - Alkalinity Trends in the Baltic

From Müller et al., 2016

Rehder, Carstensen, Gustafsson HELCOM S&C, May 2018

Proposed acidification indicators for the Baltic Sea

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pCO2 – 15 year time line

From Schneider and Müller 2018

– 15 years of pCO2 measurements on VOS Finnmaid (and Finnpartner) – long-term joined effort of Alg@line and – Integrated understanding recently published in a Springer monograph

Baltic (2008- 15) BATS (1983-2011) Slope (µatm yr−1) 4.6 - 6.1 1.62 P-value <0.01 <0.01 R2 0.007 - 0.023 0.16

Rehder, Carstensen, Gustafsson HELCOM S&C, May 2018

Proposed acidification indicators for the Baltic Sea

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Calculated net carbon production in the different basins during the spring bloom for 2009. Schneider and Müller, 2018

pCO2 – Productivity assessment

8 . ) (        t F z C iNCP

AS eff T

FAS – CO2 exchange with the atmosphere; Zeff – effective penetration depth; Δt considered time intervall;

– Independent of C/N/P stoichiometry

Rehder, Carstensen, Gustafsson HELCOM S&C, May 2018

Proposed acidification indicators for the Baltic Sea

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7.6 7.8 8.0 8.2 8.4 1950 1960 1970 1980 1990 2000 2010 2020 pH Gotland Basin, Baltic Sea 7.8 8.0 8.2 8.4 1950 1960 1970 1980 1990 2000 2010 2020 pH Bornholm Basin, Baltic Sea

pH – Obstacles – Methods used so far not suitable for long-term analysis – Difficult to separate any true signal from methodological problems – Re-calibration not possible

pH-time series BY 15 (SMHI data)

• Glas electrode
• Monthly cruises
• Only at monitoring stations
• 1995-2015 to detectable trend

Søren Sørensen Carlsberg Laboratorien Kopenhagen, 1909 “Potentia Hydrogenii”

Rehder, Carstensen, Gustafsson HELCOM S&C, May 2018

Proposed acidification indicators for the Baltic Sea

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pH – recent progress – Large variablility calls for high spatiotemporal resolution – Until now lack of reference materials for S<20 – Strong, instrument- depending salinity dependence of pH-electrodes – No user-friendly instrument for brackish waters – Considerable progress made within BONUS PINBAL

Rehder, Carstensen, Gustafsson HELCOM S&C, May 2018

Proposed acidification indicators for the Baltic Sea

11

pH – recent progress – Large variablility calls for high spatiotemporal resolution – Until now lack of reference materials for S<20 – Strong, instrument- depending salinity dependence of pH-electrodes – No user-friendly instrument for brackish waters – Considerable progress made within BONUS PINBAL

BONUS INTEGRAL Integrated carboN and TracE Gas monitoRing for the bALtic sea

A BONUS Blue Baltic Research Project

BONUS INTEGRAL

• Funded 07/2017– 06/2020
• 8 partners, 5 nations, 2.1 Mio €

Key Theme 5.1 Developing and improving the scientific basis for integrated monitoring programmes for continuous assessment of ecological status and human pressures 5.2 Developing and testing innovative in situ, remote sensing and laboratory techniques

A BONUS Blue Baltic Research Project

BONUS INTEGRAL

Overarching ideas:

• Use of the (extended) ICOS network for

biogeochemical monitoring of the Baltic Sea, in combination to existing monitoring programs

• Improved ASE-parameterizations for the Baltic Sea
• Provide best experimentally based seasonal

concentration charts for carbon dioxide, methane, and nitrous oxide

• Full integration of carbon system into high

resolution physical biogeochemical model

• Advice for countries with upcoming ICOS

infrastructure

• Model-ouput based recommendations on effective

biogeochemical monitoring

Rehder, Carstensen, Gustafsson HELCOM S&C, May 2018

Proposed acidification indicators for the Baltic Sea

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Summary and Discussion points

– Inorganic carbon system parameters as the primary tool to assess acidification – Also allowing important insights on eutrophication and the link between net productivity and deep water oxygen demand – Methods (almost) readily developed – Methods allow an important bridge in the spatio-temporal coverage between discrete (monitoring cruises) and entire system (remote sensing / modelling) approaches – Major advantage for ecosystem assessment in a world with MULTIPE DRIVERS

Rehder, Carstensen, Gustafsson HELCOM S&C, May 2018

Proposed acidification indicators for the Baltic Sea

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Rehder, Carstensen, Gustafsson HELCOM S&C, May 2018

Proposed acidification indicators for the Baltic Sea

Vision

– Improved Assessment (Monitoring) of the Baltic Sea biogeochemistry through continuous CO2 and GHG-observations on a basin wide scale

• Carbon system parameters as best indicator for

– Eutrophicaton – Acidification

• Non-CO2 GHG flux as ecosystem health indicator
• High spatiotemporal resolution bears potential to detect trends and gradual

changes

• A Baltic Sea marine GHG measurement network
• Potential for extension and remote sensing based extrapolation

16

Rehder, Carstensen, Gustafsson HELCOM S&C, May 2018

Proposed acidification indicators for the Baltic Sea

Müller, J.D., Schneider, B. and Rehder, G., (2016). Long-term alkalinity trends in the Baltic Sea and their implications for CO2-induced acidification. Limnol. & Oceanogr., 61: 1984-2002. Bakker, D.C.E., Pfeil, B., Landa, C.S., Metzl, N., Brien, ..... Schneider, B. ..... and Xu, S., (2016). A multi-decade record

• f high-quality fCO2 data in version 3 of the Surface Ocean CO2 Atlas (SOCAT). Earth System Science Data, 8(2):

383-413. Le Quéré, C., Moriarty, R., Andrew, R.M., Canadell, J.G., Sitch, .... Rehder, G.,….. and Zeng, N., (2016). Global Carbon Budget 2015. Earth System Science Data, 7(2): 349-396. Müller, J.D., Schneider, B., Aßmann, S. and Rehder, G., (2018). Spectrophotometric pH measurements in the presence of dissolved organic matter and hydrogen sulfide. Limnology and Oceanography: Methods, 16: 68-82. Le Quéré, C., Andrew, R.M., Friedlingstein, P., Sitch, S., Pongratz,.....Rehder,G., ….. and Zhu, D., (2018). Global Carbon Budget 2017. Earth System Science Data, 10(1): 405-448. Schneider, B. and Müller, J.D., (2018). Biogeochemical Transformations in the Baltic Sea - Observations Through Carbon Dioxide Glasses. Springer Oceanographie. Springer. submitted Müller, J.D., Bastkowski, F., Sander, B., Seitz, S., Turner, D.R., Dickson, A.G. and Rehder, G., submitted. Metrology for pH measurements in brackish waters – part 1: Extending electrochemical pHT measurements of TRIS buffers to salinities 5 – 20. Frontiers in Mar. Biogeochemistry. Müller, J.D. and Rehder, G., submitted. Metrology of pH measurements in brackish waters – part 2: Experimental characterization of purified meta-Cresol Purple for spectrophotometric pHT measurements. Frontiers in Mar. Biogeochemistry.

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