Föreläsning på Grundvattendagarna 2013

1. 2013‐11‐10
Riparian zone control on DOC in boreal streams:
”Does this amplify the climate response?”
Kevin Bishop, Thomas Grabs, Hjalmar Laudon, Jan Seibert
Department of Aquatic Science and Assessment
Photo: Erkki Oksanen, Met
Dissolved Organic Carbon (DOC)
Natural Organic Matter
– A nasty beast
Photo: Stefan Löfgren
1

2. 2013‐11‐10
DOC in
Fenno‐Scandian
Surface Water
DOC (mg L-1)
10
There is lots –
defines
aquatic life,
1
0.1
impacts
drinking water
DOC is increasing!
• 50%‐100% increase
1990‐2005
Monteith, et al. 2007 Nature
Hyttebörn et al. in prep
2

3. 2013‐11‐10
Why is DOC is Rising?
• Temperature first explanation
• Other Suggestions:
Acidification Recovery
Rainfall, Ionic strength,
N‐dep, CO2
Still looking for mechanism(s)…
Standardised DOC concentration
3
2
Lakes
Streams
1
0
-1
2000
1999
1998
1997
1996
1995
1994
1993
1992
1991
1990
1989
1988
-2
C. Freeman, et. al. Nature (2001)
Flow and Sulfate
Predict DOC in 28 Swedish Rivers 1970-2005
60
COD (KMnO4 [mg/l])
55
50
45
40
35
30
25
20
1970
1980
1990
2000
Year
Future Climate:
25% increase in runoff
6% higher DOC
Erlandsson et al.,
Global Change Biology (2007)
3

4. 2013‐11‐10
Flow and Sulfate
Predict DOC in 28 Swedish Rivers 1970-2005
60
COD (KMnO4 [mg/l])
55
50
45
40
35
30
25
20
1970
1980
1990
2000
Year
Future Climate:
25% increase in runoff
6% higher DOC
Erlandsson et al.,
Global Change Biology (2007)
4

5. 2013‐11‐10
Shallow Groundwater has low DOC (< 2 mg/L),
Streams are 10, 20, 30 mg/L
Runoff DOC comes from ”Connected” Organic Soils
in the Near‐Stream/Rpiarian Zone and Wetlands
Painting the boreal waterscape brown
Origins of DOC in
the Riparian Zone
Department of Aquatic Science and Assessment
5

6. 2013‐11‐10
Riparian Zone,
Hillslope/Upland,
Hydromorphic
Soils
Fixed
Respired
CO2
CO2
Various Soils (often podsols in SE)
Fixed
Respired
CO2
CO2
Depth to Gw-Table
Oxic conditions
Biological Activity 
Anoxic conditions
µ-bial Decomposition 
Biological Activity

µ-bial Decomposition
Riparian Zone,
Hillslope/Upland,
Hydromorphic
Soils
Fixed
Respired
CO2
CO2

Various Soils (often podsols in SE)
Fixed
CO2
Respired
CO2
C
CC
C
Carbon
storage
Carbon
storage
6

7. 2013‐11‐10
Riparian Zone,
Hillslope/Upland,
Lateral drainage
Vertical drainage
(More)
C
C
C
C
C
C
C
C
C-Transport
GW-Flow
Riparian Zone,
Hillslope/Upland,
Lateral drainage
Vertical drainage
(More)
longterm
short term
C
C
C
C
C
C
C
C
CC
C
GW-Flow
C
C-Transport
7

8. 2013‐11‐10
Riparian Concentration Integration Model (RIM)
TOC [mg/L]
2
4
6
8
0
10
0
0.2
0.4
0.6
0.8
1
20
40
60
80
Load 
0
Depth below surface [m]
Groundwater level [m below surface]
Runoff [mm/d]
0
0.2
0.4
 q(z)  c(z) dz
0.6
0.8
1
Seibert et al. 2009 (Hess)
8

9. 2013‐11‐10
Chemostat
– whatever passes gets the same ”color”
-- Instantaneous, no storages involved
- Vertically differentiated
Riparian Chemostat
Static
Landscape/Catchment Water
≠ Runoff Chemistry
The Riparian Zone is:
1. A Solution
2. A Panacea
3. The Ultimate Black Box
4. One zone to Rule them all…
9

10. 2013‐11‐10
Krycklan Riparian Observatory
Testing the Riparian Hypothesis/Dream
Riparian
observatory
13 Sites
15
30
5 Depths/ Site
2 Lysimeters/ Depth
45
1 Gw-Well/ Site
60
9 Sampling Campaigns
75
TOC*, pH, absorbance,
anions, cations, O18
+ lots of help!
Riparian Soils: Temporal Variations
(with soil temperature)
dry
moraine
wet
moraine
fluvial
sediment
10

11. 2013‐11‐10
Seasonally Variable Chemostat [sic]
Riparian Chemostat
Varying with:
Depth
Season
Temperature Sensitivity of DOC profile
– captures seasonality, improves fit!
11

12. 2013‐11‐10
Modeling a decade of DOC Dynamics
Aneboda –
Southern Sweden
Gammtratten –
Northern Sweden
Why does the Riparian Zone Amplify
Climate Change effects on DOC?
• Warmer
• More rain
• Less snow
• More runoff all year
Department of Aquatic Science and Assessment
12

13. 2013‐11‐10
Seasonal Chemostat and Climate Change
‐ less snowmelt, more autumn flow
‐ more flows when soils warm
TOC increases in a future climate
Statistical
Regression a
Mean TOC
Increase
Autumn peak
difference
Riparian
Model b
~1 mg/L (6%)
~4 mg/L (25%)
…
~10 mg/L
IPCC Hadley A Scenario,
1.5 C temperature increase, 25% more runoff (HBV modeling).
Department of Aquatic Science and Assessment
aErlandsson
et al., 2008 Global Change Biology ; bWinterdahl et al., 2011, Water Resources Research.
13

14. 2013‐11‐10
Flow and Sulfate Predict DOC
in 28 Swedish Rivers 1970-2005
60
COD (KMnO4 [mg/l])
55
50
45
40
35
30
25
20
1970
1980
1990
2000
Year
Future Climate:
25% increase in runoff
6% higher DOC
Erlandsson et al.,
Global Change Biology (2007)
Warmer, wetter climate amplifies
DOC export from the Riparian Zone:
Shift flow from Spring flood (cold soil)
to rain events through warmer soils
Department of Aquatic Science and Assessment
14

15. 2013‐11‐10
Thanks for your time!
…and all these years
to dig into the RZ with
friends and colleagues.
©Bill Waterson
15