1. The Impact of Climate on Peatland
Soil Dissolved Organic Carbon Export
Patrick Mc Entee
Supervisor : Dr Eleanor Jennings

2. Objectives
The aim of this project was to measure the effect of
temperature and moisture on peatland soil pore-water
dissolved organic carbon (DOC) concentration.
A generalised watershed loading functions model (GWLF)
was to be calibrated and validated and then used to
hindcast past DOC export based on historical weather
data.
Why? Data on peatland catchment DOC export to surface
waters could influence carbon budgeting, peatland
preservation and drinking water treatment processes

3. (Freeman et al. 2012)
Factors Influencing Decomposition

4. Climate Change
• Climate change is being caused by increased
greenhouse gas concentrations in the atmosphere
• This is predicted to cause:
– Higher maximum temperatures
– Higher minimum temperatures
– More frequent heat waves
– Increased drought frequency
– Increased precipitation extremes
(Cubasch et al., 2013)

5. Aerobic Enzymes

6. Data from the Glenamong River 2010-2011. (Ryder et al. 2014)
Grey line = mean daily DOC estimate. Black Squares = mean daily DOC.
Thin Black line = Discharge. Thick black line = weighted mean for each significant regime
DOC Export to Freshwater

7. • Rainfall 10 year average
to 2010: 2022 mm year-1
• Rarely goes above 25C
• Rarely goes below -5C
(Ryder et al. 2014)

8. METHODS

9. METHODS

10. METHODS

11. METHODS

12. METHODS
50 ml

13. FLUSH
METHODS
50 ml

14. METHODS
50 ml
FLUSH
0.45 µm
FILTER

15. METHODS
50 ml
FLUSH
0.45 µm
FILTER
Measure

16. 50 ml
METHODS
FLUSH
0.45 µm
FILTER
Measure

17. The 5 °C incubations between weeks significantly different, ~13 vs ~7 mg/L; p < 0.001; n= 9.
The 5 °C and 10 °C soil water concentrations for week three, ~7 vs ~11 mg/L; p = 0.032; n= 9.
𝑸 𝟏𝟎 =
𝑪𝒐𝒏𝒄𝒆𝒏𝒕𝒓𝒂𝒕𝒊𝒐𝒏 𝑻𝟐
𝑪𝒐𝒏𝒄𝒆𝒏𝒕𝒓𝒂𝒕𝒊𝒐𝒏 𝑻𝟏
= 2.20 𝑬𝒂 = 𝑹 ∗ 𝒍𝒏(𝑸 𝟏𝟎)/(𝟏/𝑻𝟏
− 𝟏/𝑻𝟐
) = 4.37 kJ gC-1

18. There was a significant difference in soil pore DOC concentrations between week six
and week seven, ~13 vs ~24 mg L-1 ; p < 0.001; n=18. Reflects that of other studies.

19. Measured streamflow over a four month period and the corresponding model
output, r2 = 0.78.
MODEL
0
0.5
1
1.5
2
2.5
3
3.5
4
4.5
21-Oct-02 21-Dec-02 21-Feb-03 21-Apr-03 21-Jun-03
cmday-1
Date
Measured
Model

20. 0
2
4
6
8
10
12
14
16
1/1/2004 4/1/2004 7/1/2004 10/1/2004
DOCmgL-1
Date
Modelled
Measured
Stream water DOC concentrations measured during 2004 and corresponding
model output, r2 = 0.48
MODEL
0
2
4
6
8
10
12
14
16
1/1/2004 4/1/2004 7/1/2004 10/1/2004
DOCmgL-1
Date
Modelled
Measured

21. MODEL
Sensitivity analysis. Temperature driven activation energy (Ea) had less impact
than moisture driven anaerobic composition (AD)
0
5
10
15
20
25
7/20/2004 8/20/2004 9/20/2004 10/20/2004
DOCmgL-1
Date
AD 0.0481, Mean 15.08
AD 0.0381, Mean 11.94
AD 0.0281, Mean 8.81
AD 0.0181, Mean 5.68
AD 0.0081, Mean 2.55
0
5
10
15
20
25
7/20/2004 8/20/2004 9/20/2004 10/20/2004
DOCmgL-1
Date
Ea 4.54, Mean 10.87
Ea 3.54, Mean 9.77
Ea 2.54, Mean 8.81
Ea 1.54, Mean 7.97
Ea 0.54, Mean 7.24

22. Modelled soil water DOC concentrations over thirty years starting from 1966.
Cumulative plot estimated Glenamong catchment exported 6 kt or 200 t year-1
MODEL
0
5
10
15
20
25
2/1/1966 2/1/1971 2/1/1976 2/1/1981 2/1/1986 2/1/1991 2/1/1996
DOCmgL-1
Date
Cum Tot Nut
8 M
6 M
4 M
2 M
0
1966 1973.8 1981.5 1989.3 1997
Base Calendar Year
Cum Tot Nut[C] : F:GWLF - 19042106workshop - Copyworkshop filesModellingcatchmenthindcastkg

23. Conclusion
• Temperature did effect DOC concentration. The results gave an Ea of 4.37
kJ gC-1 and this was close to the 4.90 kJ gC-1 used in a calibrated
Glenamong model.
• There was an increase in DOC concentration after rewetting peat that had
a week of simulated drought conditions. This reflects measurements
from Glenamong. There may have been an enzymatic latch release and
more incubations over a longer period would be interesting to see if this
persisted.
• The GWLF model is a useful tool that could be used to estimate past and
future DOC export from peatland catchments. This could inform
environmental policy with regards to blanket bogs and could help in
water treatment processes so that carcinogenic trihalomethanes can be
reduced.

24. References
• Cubasch, U., Wuebbles, D., Chen, D., Facchini, M. C., Frame, D., Mahowald, N., & Winther,
J.-G. (2013). Introduction. In: Climate Change 2013: The Physical Science Basis. Contribution
of Working Group I to the Fifth Assessment Report of the Intergovernmental Panel on
Climate Change. Climate Change 2013: The Physical Science Basis. Contribution of Working
Group I to the Fifth Assessment Report of the Intergovernmental Panel on Climate Change,
119–158. http://doi.org/10.1017/CBO9781107415324.007
• Feehan, J., O’Donovan, G. (1996) The Bogs of Ireland: An Introduction to the Natural,
Cultural and Industrial Heritage of Irish Peatlands, University College Dublin,
Environmental Institute: Dublin.
• Freeman, C., Fenner, N., Shirsat, A.H. (2012) ‘Peatland geoengineering: an alternative
approach to terrestrial carbon sequestration’, Philosophical Transactions of the Royal
Society A: Mathematical, Physical and Engineering Sciences, 370(1974), 4404–4421,
available: http://rsta.royalsocietypublishing.org/cgi/doi/10.1098/rsta.2012.0105.
• Ryder, E., de Eyto, E., Dillane, M., Poole, R., Jennings, E. (2014) ‘Identifying the role of
environmental drivers in organic carbon export from a forested peat catchment’, Science of
the Total Environment, 490, 28–36, available:
http://dx.doi.org/10.1016/j.scitotenv.2014.04.091.

25. Thank You
Dr Eleanor Jennings
Dr Elizabeth Ryder
Luybov Bragina
Allison Murdock