Methane dynamics in alpine wetlands

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Methane dynamics in alpine wetlands

Methane dynamics in

alpine wetlands

J. Zeyer

Institute of Biogeochemistry and Pollutant Dynamics

D-UWIS

ETH Zurich

zeyer@env.ethz.ch

Workshop Berne

Sep. 12, 2011


Content of talk and reseach goals

1. Wetlands on 50, 2000 und 4000 m.a.s.l.

2. Three key players: Plants, methanogens and methanotrophs

3. Field sites: Göscheneralp, Oberaar and Cadagno

4. Results

5. Conclusions & hypotheses

Goals:

• Role of plants

• Seasonal emission patterns

• Correlate profiles with microbiology

• Quantification and modelling


Content

1. Wetlands on 50, 2000 und 4000 m.a.s.l.

2. Three key players: Plants, methanogens and methanotrophs

3. Field sites: Göscheneralp, Oberaar and Cadagno

4. Results

5. Conclusions & hypotheses


Wetlands in Northern Siberia on 50 m.a.s.l.

(Lena Delta, 72.4 o N)

Carex aquatilis


Wetlands in the Alps on 2000 m.a.s.l.

(Göschener Alp, 46.7 o N)

Carex rostrata

Carex limosa


Wetlands under the equator on 4000 m.a.s.l.

(Rwenzori Mountains, 0.4° N)

Carex runssorensis


Wetlands on 50, 2000 und 4000 m.a.s.l.:

What is different? What is common?

Different: Altitude

Common in all 3 habitats:

Very wet, cool temperatures,

Productive vegetation, a lot of C org ,

Plants in water (Carex spp.)

Körner C., Alpine Plant Life, Springer 1999


Content

1. Wetlands on 50, 2000 und 4000 m.a.s.l.

2. Three key players: Plants, methanogens and methanotrophs

3. Field sites: Göscheneralp, Oberaar and Cadagno

4. Results

5. Conclusions & hypotheses


The 1 st player in the game:

Carex spp. (on Göschener Alp)

Carex rostrata

(Schnabelsegge)

(stehender

Fruchtstand)

Carex limosa

(Schlammsegge)

(hängender

Fruchtstand)


The 1 st player in the game:

Carex spp. with aerenchyma

Carex

rostrata

Aerenchyma of

Carex rostrata


2 nd and 3 rd player:

Methanogenic and methanotrophic MOs

Rhizosphere

Methanotrophic

MOs

CH 4 + O 2 -->

CO 2 + H 2 O

c

Methanotrophic MOs

Atmosphere

CO 2 + CH 4


Content

1. Wetlands on 50, 2000 und 4000 m.a.s.l.

2. Three key players: Plants, methanogens and methanotrophs

3. Field sites: Göscheneralp, Oberaar and Cadagno

4. Results

5. Conclusions & hypotheses


Altitude:

1910 m.a.s.l.

Bedrock:

Siliceous

Plants:

C. rostrata

C. limnosa

Juncus spp.

Wetland Göscheneralp (Uri)


Altitude:

2310 m.a.s.l.

Bedrock:

Siliceous

Plants:

C. rostrata

Wetland Oberaar (Berne)


Altitude:

2090 m.a.s.l.

Bedrock:

Siliceous &

calcareous

Plants:

C. rostrata

Juncus spp.

Wetland Cadagno (Ticino)


S. Liebner

S. Schwarzenbach

Wetland Göscheneralp (Uri)

...in winter


S. Francchini

A. Gauer

I. Erny

Wetland Oberaar (Berne)

...on a rainy day


Content

1. Wetlands on 50, 2000 und 4000 m.a.s.l.

2. Three key players: Plants, methanogens and methanotrophs

3. Field sites: Göscheneralp, Oberaar and Cadagno

4. Results

5. Conclusions & hypotheses


Role of plants:

Emission of methane with and without Carex

Cadagno

Group A:

Cutting of Carex

1 cm below Watersurface

Group B:

Cutting of Carex

2 cm above Watersurface


Role of plants:

Emission of methane with and without Carex

Results group A

Results group B

Cadagno

CH 4 [ppm]

70

60

50

40

30

with plants (t 0)

cut -1cm (t 1h)

cut -1cm (t 20h)

y = 1.7531x + 8.0202

Flux = 340 mg m ‐2 d ‐1

y = 0.0813x + 4.1048

Flux = 13 mg m ‐2 d ‐1

CH 4 [ppm]

70

60

50

40

30

with plants (t 0)

cut +2 cm (t 1h)

cut +2cm (t 20h)

y = 1.7555x + 11.21

Flux y = = 1.0108x 340 mg + m8.2953

‐2 d ‐1

Flux = 204 mg m ‐2 d ‐1

y = 1.0817x + 4.7804

Flux = 217 mg m ‐2 d ‐1

20

10

y = 0.0622x + 2.591

Flux = 12 mg m ‐2 d ‐1

20

10

0

0 10 20 30

Time[min]

0

0 5 10 15 20 25 30

Time[min]

Result: Cutting reduces “chimney effect” by 40 % (+ 2 cm)

and 95 % (-1 cm), respectively!


Role of plants:

Emission of CH 4 day and night

Cadagno

mg m- 2 d -1

400

350

300

250

200

150

Flux Chamber A

360

337

295

384

mg m- 2 d -1

400

350

300

250

200

150

Flux Chamber B

241 244

266

279

100

100

50

50

0

1.9.09, 15.30 1.9.09, 21.30 2.9.09, 05.30 2.9.09, 15.00

0

1.9.09, 15.30 1.9.09, 21.30 2.9.09, 05.30 2.9.09, 15.00

Result: No pronounced day/night effect

stomata does not play a major role


Seasonal pattern:

Subsurface temperatures Oct 2008 to Sep 2009

Göscheneralp

Liebner S.,

Schwarzenbach S.P.

& Zeyer J.

Biogeochemistry

(in press)


Seasonal pattern:

Profiles of methane, oxygen and temperature

Göscheneralp

Liebner S.,

Schwarzenbach S.P.

& Zeyer J.

Biogeochemistry

(in press)


Seasonal pattern:

Emissions and pore water concentrations of CH 4

Göscheneralp

350

300

250

200

150

100

50

0

Methane Emissions

(mg/m 2·d)

700

600

500

400

300

200

100

0

Methane Conc. in Subsurface

(µmol/lit)

0-20 cm 20-40 cm

Result: Emissions follow more or less the vegetation.

Methane is produced in winter, however it is trapped below the ice


Correlate profile with microbiology:

Nov 2008: Profiles of CH 4 , O 2 and Temp

Göscheneralp


Correlate profile with microbiology:

Nov 2008: Copy numbers of mcrA and pmoA

Göscheneralp

mcrA serves as a proxy

for methanogens

pmoA serves as a proxy

for methanotrophs

Liebner S.,

Schwarzenbach S.P.

& Zeyer J.

Biogeochemistry

(in press)


Quantification:

Emissions and CH 4 profiles (low resolution)

185 mg

m -2 d -1

CH 4 entrapped in box

Cadagno

Depth (cm)

Oxidation of CH 4

Diffusion of CH 4 7.4 mg m -2 d -1

Production of CH 4

Fick‘s Law:

Flux (F) = -D•dc/dz

Result: Most of the CH 4 escapes

through the aerenchyma of the

plants to the atmosphere


Quantification:

CH 4 profiles (Oberaar, Aug. 2011, high resolution)

Oberaar

Wetland Oberaar (04.08.2011)

Methane conc. [µM]

0

0 50 100 150 200

Depth below water surface [cm]

‐10

‐20

‐30

‐40

‐50

‐60


Content of talk and reseach goals

1. Wetlands on 50, 2000 und 4000 m.a.s.l.

2. Three key players: Plants, methanogens and methanotrophs

3. Field sites: Göscheneralp, Oberaar and Cadagno

4. Results

5. Conclusions & hypotheses


Conclusions and hypotheses

O 2

Ebullition

Transport

through

aerenchyma

CH 4

CH 4

O 2

Oxidation

CH 4

O 2

CO 2

Oxidation

Methane oxidation:

CH 4 + 2 O 2 CO 2 + 2 H 2 O

CH 4

Diffusion

Decomposition

of organic

matter

Methanogenesis:

‐ Hydrogenotrophic: CO 2 + 4 H 2 2 H 2 O + CH 4

‐ Acetotrophic: CH 3 COOH CO 2 + CH 4


Conclusions and hypotheses

Plants

(Carex sp.)

Mosses

(Calliergon sp.

Sphagnum sp.)

Conc. CH 4

1. Profiles have several

sources and sinks

Sink

Diffusion

Source

2. Methanogens and

methanotrophs overlap

-20 Diffusion

Sink

3. Consider microorganisms,

plants and

mosses

4. Modelling has to go

beyond “50%

oxidation”

-40

Depth

[cm]

Diffusion

Source

(Dream)equation required for climate modelling:

Emission = f (Sources, Sinks, Carex, Mosses,

Microorganisms, Structure, Season, etc.)


Wetland Cadagno

(Aug. 29, 2011)

Carex rostrata

leaves

Sphagnum sp.

photosynthetically

active

Water

table ?

Sphagnum sp.

Decaying ->

Methane??

Carex rostrata

rhizosphere ->

Oxygen ??

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