ICOS Science Conference, Session 4

1. Monitoring land-ocean
carbon fluxes at pan-
European scale
Stacey L. Felgate
stacey.felgate@noc.ac.uk
@staceyfelgate

2. National Oceanography Centre
What is the land-ocean carbon flux?
The export of carbon from land to sea via the land-ocean aquatic continuum (LOAC).
Environments: Soil and ground water
Fluvial waters (headwater, streams, rivers)
Modified (constructed) waterbodies
Lakes, natural ponds, and freshwater wetlands
Transitional waters and coastal wetlands
Sub-fluxes: Lateral C fluxes (land - aquatic)
Vertical C fluxes (aquatic – atmosphere)
Vertical C fluxes (aquatic – sediment)
This is a significant and changing part of the global C cycle with implications for climate, environment, & society.
Figure from Felgate et al. (2020)
Transcends traditional disciplinary boundaries

3. National Oceanography Centre
What is the land-ocean carbon flux?
The export of carbon from land to sea via the land-ocean aquatic continuum (LOAC).
Environments: Soil and ground water
Fluvial waters (headwater, streams, rivers)
Modified (constructed) waterbodies
Lakes, natural ponds, and freshwater wetlands
Transitional waters and coastal wetlands
Sub-fluxes: Lateral C fluxes (land – aquatic)
Vertical C fluxes (aquatic – atmosphere)
Vertical C fluxes (aquatic – sediment)
This is a significant and changing part of the global C cycle with implications for climate, environment, & society.
i.e. soil OC
Land Ocean
Figure from Lauerwald et al. (2017)

4. National Oceanography Centre
What is the land-ocean carbon flux?
The export of carbon from land to sea via the land-ocean aquatic continuum (LOAC).
Environments: Soil and ground water
Fluvial waters (headwater, streams, rivers)
Modified (constructed) waterbodies
Lakes, natural ponds, and freshwater wetlands
Transitional waters and coastal wetlands
Sub-fluxes: Lateral C fluxes (land – aquatic)
Vertical C fluxes (aquatic – atmosphere)
Vertical C fluxes (aquatic – sediment)
This is a significant and changing part of the global C cycle, with implications for climate, environment, & society.
Figure from Ciais et al. (2013)

5. National Oceanography Centre
Why is monitoring the land-ocean C flux important?
Figure from Ciais et al. (2013)
• Land-ocean C fluxes are a ‘black box’ of uncertainty.
• Land – freshwater flux has increased by ~1 Pg C yr-1 since the
industrial revolution.
Land use change & increased wastewater
• Aquatic – marine flux has stayed relatively consistent.
• Is the marine flux really constant? Increased GHG fluxes?
• Understanding this flux will allow for:
Prediction
Mitigation
Management
• Scientific and societal benefits

6. National Oceanography Centre
Why do we need pan-European monitoring?
Figures taken from EEA Signals 2020 (https://www.eea.europa.eu//publications/eea-signals-2019-land)
The LOAC doesn’t obey national boundaries – fluxes
operate at land-mass scale whilst studies operate at
catchment and sub-catchment scale.
Drainage from soils into aquatic systems estimated at
~114 Tg C yr-1 (20 years old).
No robust estimates of how much of this makes it to the
ocean, or of the other associated fluxes.
Very real implications for EU policy:

7. National Oceanography Centre
RINGO Task 1.4
What are the requirements for monitoring land-ocean carbon fluxes at
pan-European scale?
• What data is already collected?
• What, when, and where should we measure?
• How can we deliver this most efficiently?

8. National Oceanography Centre
RINGO Task 1.4
What are the requirements for monitoring land-ocean carbon fluxes at
pan-European scale?
• What data is already collected?
• What, when, and where should we measure?
• How can we deliver this most efficiently?
A huge part of Task 1.4 was knowledge exchange, bringing together a
diverse group of researchers actively studying aspects of the land-ocean
C flux and creating a common understanding and vocabulary upon which
to build a truly collaborative, multi-disciplinary collective. Thank you to
everyone involved for their efforts, and for making this such an enjoyable
and productive project.

9. National Oceanography Centre
What data already exists?
• Online questionnaire (30 respondents, >40 ongoing studies)
• Collated our own work (>40 partners, >80 ongoing studies)
• Literature review – Monumental task!
There is no shortage of data, but it isn’t easy to find or linked up:
• Data accessibility
• Parameter mismatch
• Methodological differences
Studies tend to be short-lived (due to funding cycles).
Rarely span multiple environments – freshwater or marine.
Rarely capture ephemeral events.

10. National Oceanography Centre
Where should we monitor?
• 125,000 different waterbodies
• 1.2 million km combined river length
• 15,000 km2 of transitional waters
We can’t possibly prescribe exact locations
(nor should we!) but we can guide their
selection.

11. National Oceanography Centre
Figure from JRC (https://esdac.jrc.ec.europa.eu/content/octop-topsoil-organic-carbon-content-Europe)
Figure taken from EEA Signals 2020 (https://www.eea.europa.eu//publications/eea-signals-2019-land)

12. National Oceanography Centre
When should we monitor?
Ultimately, a balance will be struck between temporal and spatial resolution according to the
available budget, and any fixed recommendation would be arbitrary at this stage.
However, we suggest monthly resolution as a minimum requirement for long-term monitoring.
Ongoing research at NOC to identify the optimum sampling frequency.
What should we monitor?
Essential Desirable
DOC Nutrients (NO3, NO2, NH4, SRP, Si(OH)4,TN, TP)
POC Selected major ions / cations (i.e. sulphate and iron)
DIC Biochemical Oxygen Demand (BOD)
PIC Chromophoric Dissolved Organic Matter (CDOM)
CO2 (pCO2) Fluorescent Dissolved Organic Matter (FDOM)
CH4 (pCH4) Alkalinity
Water temperature Dissolved Oxygen (DO)
Conductivity Turbidity
pH Turbulence
Water discharge Depth

13. National Oceanography Centre
LOCATE
The first ever coordinated sampling of the major rivers in
Great Britain (www.locate.ac.uk).
Represents a ‘pilot study’ for landmass scale C flux
monitoring and understanding:
1. Monitoring of the flux at broad scale
2. Understanding of the drivers at key locations
3. Modelling to upscale flux and predict change
See tomorrow’s keynote by Richard Sanders.
Principal Investigator: Daniel J. Mayor (NOC)

14. National Oceanography Centre
LOCATE
Stage 1 covered ~50% of the GB landmass.
• 5 institutes, and over 100 scientists.
• Universal methods
• Internally consistent measurement
• Monthly resolution
• Representative land cover
Williamson et al., (submitted).
DOC flux from the GB land mass estimated at
1.14 Tg C yr-1. (1/10th soil C flux)
Other studies pending
But… we missed several ephemeral events!

15. National Oceanography Centre
LOCATE
Fixed sensors developed to capture high
resolution data: pCO2, oxygen, chlorophyll,
DOM quality, light attenuation, temperature,
proxy for DOC.

16. National Oceanography Centre
The WFD Network
This kind of monitoring network already exists
across Europe, designed to deliver the WFD.
Ecological / physico-chemical indicators:
Light and thermal conditions
Oxygenation
Nutrient concentrations
Acidification
Cost effective
Existing buy-in from stakeholders
Relatively secure, long-term funding stream.
46% of surface water bodies are sampled for ecological status
92,000 sites
28% of surface water sampled for chemical status
36,000 sites
Added value: incorporating carbon fluxes would
compliment existing measurement priorities.

17. National Oceanography Centre
LOCATE
In Stage 2 we conducted process studies
across a range of land cover types:
• Photodegredation
• Biodegradation
• Flocculation
• Nutrient amendment
• Temperature dependence
• DOM composition
Felgate et al., (in prep)
Targeted process studies can be
hugely powerful – cooperation from
inception to delivery could increase
knowledge acquisition rapidly.

18. National Oceanography Centre
LOCATE
Stage 3 produced a bespoke model for land-ocean DOC
export which uses a common language and partitioning
method across the freshwater and marine realms.
UniDOM (Anderson et al., 2018) transfers DOC from
land to sea, and partitions DOC according to it’s UV-
absorbing characteristics.
• Calculates CO2 fluxes.
• POC is problematic and requires further work.
Useful process-based model which could be used and
improved as part of a pan-European monitoring network.

19. Making Sense of Changing Seas
We suggest:
- Pan-European monitoring driven by national agencies
- Process studies driven by researchers/academics
- Collaboration across the land-ocean C flux community, from inception to delivery
- Numerical modelling to extrapolate and forecast
- Investment in autonomous technology
Full report will be available on the ICOS RINGO website (deliverables) shortly.
stacey.felgate@noc.ac.uk