Methane as a greenhouse gas and food web fuel in some boreal lakes

oeschger.unibe.ch

Methane as a greenhouse gas and food web fuel in some boreal lakes

Methane as a greenhouse gas and

food web fuel in some boreal lakes

Paula Kankaala

University of Eastern Finland, Joensuu

campus, Box 111, FI-80101 Joensuu,

Finland

The results presented here are mainly

from studies at Lammi Biological

Station, University of Helsinki, Finland


Objectives of the studies

• Several projects funded mainly by the

Academy of Finland (from 1991)

– Carbon cycle in boreal lakes, impacts of climate

change

– Lakes as sources and sinks of CO 2 and CH 4

• Littoral and pelagic CH 4 fluxes

• Methanotrophy

• MOB in the diets of crustacean zooplankton of

small stratified lakes (δ 13 C, δ 15 N, PFLA)


Littoral CH 4 emissions were studied in

the vegetated stands of four lakes

Lake Area km 2 TotP µg L -1

Alinen Rautjärvi 0.50 20

Ekojärvi 0.74 22

Pääjärvi 13.4 12

Vesijärvi, Enonselkä 26 36

and in experimental stands of

Equisetum fluviatile


• CH 4 transport via

aerechymal tissues

• Closed-chamber

technique

• Board-walks in the littoral

zone


…or sampling in a boat


Pelagic area:

Floating chambers and/or measurements of CH 4

concentration in the uppermost 30-cm water layer


Gas samples were analysed with gas chromatograph

equipped with flame ionization detector (FID)


Vegetated littoral areas

100

80

mg CH4 m -2 d -1

60

40

20

0

13/05/2002 12/06/2002 12/07/2002 11/08/2002 10/09/2002 10/10/2002 09/11/2002

Seasonal dynamics of CH 4 efflux (mg m -2 d -1 )

from a Schoenoplectus lacustris stand, Alinen

Rautjärvi


1500

1000

1997

1500

1000

1998

1500

1000

1999

CH4 emission

biomass

500

500

500

0

1-May 1-Jul 1-Sep 1-Nov

0

1-May 1-Jul 1-Sep 1-Nov

0

1-May 1-Jul 1-Sep 1-Nov

Lake Vesijärvi: Efflux of CH 4 (mg m -2 d -1 ) and biomass

of green shoots (g DW m -2 ) in a dense P. australis

stand .


CH 4 effluxes from vegetated littoral stands, mol

CH 4 m -2 (ice-free period) -1

and P. australis

Species

Equisetum

fluviatile

Equisetum

fluviatile

Lake/exp

Sediment

type

LOI

Max

biomass Total efflux Reference

g DW m -2 mol CH 4

m -2

exp.

mesocosm sand 1 ± 0.2 290 ± 70 0.16 Kankaala & Bergström, 2004

exp.

mesocosm silty gyttja 8 ± 0.3 1190 ± 120 2.29 Kankaala & Bergström, 2004

Equisetum

fluviatile Pääjärvi sandy gyttja 8 700 ± 300 2.72 Hyvönen et al. 1998

E. fluv. & P.

australis Ekojärvi silty gyttja 12 ± 4 80 ± 40 0.78 Kankaala et al. 2005

Schoenoplectus

lacustris

Alinen

Rautjärvi

gyttja sand and

Phragmites

australis

P. australis inner

zone

P. australis, outer

zone

Vesijärvi

Scirpus peat 40 ± 35 140 ± 60 0.18 Kankaala et al. 2005

Alinen

Rautjärvi gyttja sand 2 ± 1 70 ± 10 0.22 Kankaala et al. 2005

Phragmites

Vesijärvi peat 85 ± 3 800 ± 100 3.62 Kankaala et al., 2004

Phragmites

peat, 55 ± 5 480 ± 440 7.67 Kankaala et al., 2004

detritus from Lemna trisulca


CH 4 emissions of vegetated

littoral areas

• Seasonal variation correlated with

temperature or plant biomass

(substrate limited areas)

• Between-stand variation correlated with

productivity of CH 4 in the sediment but

not with the sediment organic matter

content


Pelagic zone

In many small boreal lakes the water column is steeply stratified by temperature and oxygen

Incomplete spring

mixing

0.0

Temperature o C

0.0

O 2 mg L -1

-0.5

-0.5

-1.0

-1.0

Depth m

-1.5

-2.0

Depth m

-1.5

-2.0

-2.5

-3.0

-3.5

Mekkojärvi

4

6

8

10

12

14

16

18

20

150 180 210 240 270 300

150 180 210 240 270 300

May Jun Jul Aug Sep Oct May Jun Jul Aug Sep Oct

-2.5

-3.0

-3.5

0

4

6

8

10


The highest CH 4 concentrations are measured in late

summer in the hypolimnion

Depth m

-0.5

-1.0

-1.5

Mekkojärvi

The maximum CH 4

concentrations

measured in the study

lakes varied between

170 and 1900 µmol L -1

-2.0

-2.5

150 180 210 240 270 300

May Jun Jul Aug Sep Oct

20

40

60

80

100

120

140

160


6.0

mmol CH 4 m -2 d -1

5.0

4.0

3.0

2.0

1.0

Chamber

BLD method

0.0

01 April

2002

01 May

2002

01 June

2002

01 July

2002

01 August

2002

31 August

2002

01 October

2002

31 October

2002

The highest CH 4 emissions to the atmosphere

occur during the autumnal turnover period

(Valkea Kotinen)


CH 4 efflux from the pelagic area of the

lakes

CH 4 efflux mol m -2 (ice-free period) -1

0.7

0.6

0.5

0.4

0.3

0.2

0.1

0.0

MJ N AM TL HJ VK OnJ OrJ PJ

Littoral effluxes 0.2 – 7.7 mol CH 4 m -2

(ice-free period) -1

0.70

0.60

0.50

0.40

0.30

0.20

0.10

0.00

R² = 0.758

R² = 0.891

0.001 0.100 10.000

Lake area km 2

No anoxia in

the hypolimnion


Methanotrophy

Littoral area

• Measurements in experimental

stands of Equisetum fluviatile


Mekkojärvi 2005

CH 4 efflux or MOB act. mg C -2 d -1

600

500

400

300

200

100

0

01.05.05

01.06.05

MOB activity

Efflux to

atmosphere

02.07.05

02.08.05

02.09.05

03.10.05

03.11.05

mg C m -2 d -1

120

100

80

60

40

20

0

nd

PP

MOB

HBP

GSB

Spring Summer Autumn

Net production by phytoplankton (PP),

heterotrophic bacteria (HBP), methane

oxidizing bacteria (MOB) and green sulphur

bacteria (GBB)

nd


Autumn mixing of the water column

200

-40

150

-50

CH 4 µmol L -1

100

13 C-CH4

-60

-70

50

-80

0

10-Sep 20-Sep 30-Sep 10-Oct 20-Oct 30-Oct

-90

10-Sep 20-Sep 30-Sep 10-Oct 20-Oct 30-Oct

Type I MOB formed 32 ± 23 % of the

bacterial biomass in autumn

0-0.6 m 0.6-1.2 m

1.2-1.8 m 1.8-2.4 m

2.4-3.0 m


Mekkojärvi study in 2005, the diet of

Daphnia longispina

80 %

Algae MOB HB Chlorobium

60 %

40 %

20 %

0 %

Spring Summer Autumn 1 Autumn 2

Additions of NaH 13 CO 3 , corresponding ca. 2‰ of

the amount of total DIC in the epilimnion

Proportions of algae, MOB, HB and GSB in

the diet of Daphnia, IsoSource mixing

model results


Algae and different bacterial groups in the

diets ot crustacean zooplankton in five

lakes

• Lakes with area ranging from 0.003 to 0.145 km 2

• Water colour ranging from ca. 30 to 400 mg Pt L -1

• Sampling in May and October

• Analyses of δ 13 C and 15 N values of cladocerans and

copepods and their potential food sources

• Two-isotope IsoSource modelling of the proportions (%)

of algae, heterotrophic bacteria (HB), green suphur

bacteria (GSB), detritus and methane oxidizing bacteria

(MOB) in the diets of cladocerans and copepods


Two-isotope IsoSource model results of the proportions (%) of

algae, heterotrophic bacteria (HB), green suphur bacteria

(GSB), detritus and methane oxidizing bacteria (MOB) in the

diets of cladocerans and copepods in the five lakes

Cladocera Lake

May

Algae

HB

+GSB+detr MOB

Valkea

Mustajärvi 0-76 23-82 0-17

Valkea

Kotinen 34-86 0-58 7-14

Alinen

Mustajärvi 14-39 60-80 1-6

Nimetön 8-44 39-68 10-24

Mekkojärvi 42-69 19-39 12-19

Copepoda Lake

May

Algae

HB

+GSB+detr MOB

Valkea

Mustajärvi 0-85 15-75 0-28

Valkea

Kotinen 23-28 52-57 17-20

Alinen

Mustajärvi 45-66 9-31 24-25

Nimetön 0-17 53-70 29-35

Mekkojärvi 92-98 2-6 0-2

Oct

Valkea

Mustajärvi 0-21 63-83 15-17

Valkea

Kotinen 38-47 24-35 27-29

Alinen

Mustajärvi 17-26 40-47 34-36

Oct

Valkea

Mustajärvi 4-67 18-71 15-28

Valkea

Kotinen 24-51 41-68 8-12

Alinen

Mustajärvi 61-69 16-23 15-16

Nimetön

no data

Nimetön 0-13 50-64 35-40

Mekkojärvi 20-65 0-32 35-50

Mekkojärvi 0-29 33-53 37-50


Main results and conclusions

• Areal CH 4 effluxes from the vegetated littoral zone are

larger than from the pelagic area of the boreal lakes

- The highest CH 4 effluxes are released from emergent

vegetation stands of eutrophied lakes

- Pelagic CH 4 effluxes are inversely related to the size of the

lake

• In the pelagic area 80-90% of the CH 4 loss is due to

oxidation in the water column

• In small, stratified, boreal lakes (area


Aknowledgements

University of Helsinki:

Jussi Huotari, Tiina Käki, Anne Ojala, Jessica

Linnaluoma, Tiina Tulonen, Elina Peltomaa, Lotta

Lehtinen, Lauri Arvola

University of Jyväskylä:

Roger Jones, Sami Taipale, Hannu Nykänen, Marja

Tiirola

Finnish Environment Institute:

Irina Bergström, Pirkko Kortelainen, Miitta

Rantakari


This presentation is based on the following papers and on some unpublished results

Bergström, I., Mäkelä, S., Kankaala, P. & Kortelainen, P. 2007. Methane efflux from littoral vegetation stands of southern boreal lakes: an upscaled, regional estimate. -

Atm. Env. 41: 339-351.

Hyvönen, T., Ojala, A., Kankaala, P. & Martikainen, P 1998. Methane release from stands of water horsetail (Equisetum fluviatile) in a boreal lake. - Freshwater Biology

40:275-284.

Kankaala, P. & Bergström, I. 2004. Emission and oxidation of methane in Equisetum fluviatile stands growing on organic and sand bottoms. - Biogeochemistry 67: 21-37.

Kankaala, P. Eller, G. & Jones, R.I. 2007. Could bacterivorous zooplankton affect lake pelagic methanotrophic activity? – Fundam. Appl. Limnol. 169: 203-209.

Kankaala, P., Huotari, J., Peltomaa, E. Saloranta T. & Ojala, A. 2006. Methanotrophic activity in relation to methane efflux and total heterotrophic bacterial production in

a stratified, humic, boreal lake. - Limnol. Oceanogr. 51: 1195-1204.

Kankaala, P., Käki, T. & Ojala, A. 2003. Quality of detritus impacts on spatial variation of methane emissions from littoral sediment of a boreal lake. - Arch. Hydrobiol.

157: 47-66.

Kankaala, P., Käki, T., Ojala, A., Pajunen, H. & Arvola, L. 2005. Methane efflux in relation to plant biomass and sediment characteristics in stands of three common

emergent macrophytes in boreal mesoeutrophic lakes. - Global Change Biology 11: 145-153.

Kankaala, P., Mäkelä,S., Bergström, I., Huitu, E., Käki, T. Ojala, A., Rantakari, M. Kortelainen, P & Arvola, L. 2003. Midsummer spatial variation in methane efflux from

stands of littoral vegetation in a boreal meso-eutrophic lake. - Freshwater Biology 48: 1617-1629..

Kankaala, P., Ojala A. & Käki, T. 2004. Temporal and spatial variation in methane emissions from a flooded transgression shore of a boreal lake. - Biogeochemistry 68:

297-311.

Kankaala, P., Taipale, S. Li, L. & Jones, R.I. 2010. Diets of crustacean zooplankton, inferred from stable carbon and nitrogen isotope analyses, in lakes with varying

allochthonous dissolved organic carbon content. – Aquat. Ecol. 44: 781-795.

Kankaala, P., Taipale, S., Grey, J., Sonninen, E., Arvola, L. & Jones, R.I. 2006. Experimental δ 13 C evidence for a contribution of methane to pelagic food webs in lakes. -

Limnol. Oceanogr. 51: 2821-2827.

Kankaala, P., Taipale, S., Nykänen, H. & Jones, R.I. 2007. Oxidation, efflux and isotopic fractionation of methane during autumnal turnover in a polyhumic, boreal lake. -

J. Geophys. Res. 112, G02003, doi: 10.1029/2006JG000336.

Käki, T. Ojala, A. & Kankaala, P. 2001. Diel variation in methane emissions from stands of Phragmites australis (CAV.) TRIN. EX STEUD. and Typha latifolia L. in a boreal

lake.- Aquatic Botany 71:259-271.

López Bellido, J., Tulonen, T, Kankaala, P. & Ojala, A. 2009. CO 2 and CH 4 fluxes during spring and autumn mixing periods in a boreal lake (Pääjärvi, southern Finland). – J.

Geophys. Res. 114, DOI: 10.1029/2009JG000923.

Ojala, A., López Bellido, J., Tulonen, T, Kankaala, P. & Huotari, J. 2011. Carbon gas fluxes from a brown-water and a clear-water lake in the Boreal Zone during a summer

with extreme rain events. – Limnol. Oceanogr. 56: 61-76.

Taipale, S., Kankaala, P. & Jones, R.I. 2007. Contributions of different organic carbon sources to Daphnia in the pelagic food web of a small polyhumic lake: results from

mesocosm DI 13 C-additions. - Ecosystems 10: 757-772.

Taipale, S., Kankaala, P., Hahn, M.W., Jones, R.I. & Tiirola, M. 2011. Methane-oxidizing and photoautotrophic bacteria are major producers in a humic lake with a large

anoxic hypolimnion. - Aquat. Microb. Ecol. DOI:10.3354/ame01512.

Taipale, S., Kankaala, P., Hämäläinen, H., & Jones, R.I. 2009. Seasonal shifts in diet of lake zooplankton revealed by phospholipid fatty acid analysis. - Freshwater Biology

54: 90-104.

Taipale, S., Kankaala, P., Tiirola, M. & Jones, R.I. 2008. Whole-lake dissolved inorganic 13 C additions reveal seasonal shifts in zooplankton diet. – Ecology 89: 463-474.

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