1 Jože Pezdič et al.: 11th IPS, Quebec 2000

• THE PALEOCLIMATE

EVIDENCE IN THE PEAT

PROFILE: Stable isotope study

Authors:

Jože Pezdič, Jadran Faganeli, Simon Pirc

Department of Geology and Marine Station,

University of Ljubljana, Slovenia

2 Jože Pezdič et al.: 11th IPS, Quebec 2000

• Invitation card to Ljubljansko barje peatland south of Ljubljana, Slovenia, •14° 21’ 42” East,

•45° 53’29” North, •altitude 300 m,•mean temperature 10.03 ± 0.4 °C, •average yearly precipitation: 1332 mm

BEVŠKI MAH IS THE SOUTHERNMOST LOWLAND PEATLAND IN THE EUROPE

W

here

to f

ind

Slo

veni

a ??

IN THE SOUTH MIDDLE EUROPE –

NEAR THE MEDITERRANEAN SEA!

3 Jože Pezdič et al.: 11th IPS, Quebec 2000

Slovenia

Last glaciation

Temperatures

EVOLUTION OF SWAMP AND PEATLAND at Ljubljansko barje during last 8000 years (Encyclopedia of Slovenia, 1990)

4 Jože Pezdič et al.: 11th IPS, Quebec 2000

Examined Peat Profiles:

• BEVŠKI MAH, 300 m a.s.l., 10.0 °C Ljubljansko barje Slovenia (14° 21’ 42” E,

45° 53’29” N). Age about 8,500 years B.P. and about 2,500 at the top. Maximum thickness of peat is around 2 meters (sampled 1.6 m).

• KOSTANJEVIŠKI MAH, 310 m a.s.l. Recent marsh near the Bevški mah with

abundant, mostly Sphagnum vegetation. A 30 cm thick core with living cover was sampled

• ŠIJEC MARSH, 1200 m a.s.l., 4 °C Pokljuka plateau (E - 13° 57’, N - 46° 18’)

was tested. Recent marsh with intensive peat production. A 60 cm deep profile

5 Jože Pezdič et al.: 11th IPS, Quebec 2000

ANALYTICAL METHODS

• SAMPLE CLEANING AND PREPARATION - removal of coarse grains and wet ashing• ORGANIC ELEMENTAL ANALYSIS - total organic carbon content was analysed by Carlo Erba

1108 CHNS analyser

R: The organic carbon contents (Corg. weight %) in fossil profile range from 45.7 to 52.8 %. The pH range from 4.5 at the bottom of seam to 7.1 at the top.

R: The pH of recent peat ranges between 6.4 and 7.2 and the Corg. content from 42.7 to 45.8 %.

• CARBON STABLE ISOTOPES ANALYSIS - mass spectrometer Finnigan MAT 250 (results follow!)

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-30,0

-29,0

-28,0

-27,0

-26,0

-25,0

-24,0

0 20 40 60 80 100 120 140 160

Depth of samples [cm]

Car

bon

isot

ope

com

posi

tion

[%o]

Kostanjevica 300 m a.s.l.

Šijec - Pokljuka1,200 m a.s.l.

wood fragments wood fragments

BEVŠKI MAH 300 m a.s.l.

8,500 B.P.

2,500 B.P.

Sphagnum moss (Kostanjevica)

7 Jože Pezdič et al.: 11th IPS, Quebec 2000

• CONCLUSIONS 1Three peat locations in Slovenia, Bevški mah, Kostanjeviški

mah and Šijec marsh on Pokljuka plateau, at different altitudes and average year temperatures have been examined.

The δ13C of the bulk peat organic matter is changing successively from –28.45 to –24.45 ‰ along 1.4 m thick profile from the bottom to the top. Wood particles have quite constant values in the entire profile.

Two examined recent peat profiles (mostly some hundred years old) including growing moss have δ13C distinctly dependent upon altitude (–24.51 ‰ at 1,200 m and –28.00 ‰ at 300 m). .

8 Jože Pezdič et al.: 11th IPS, Quebec 2000

• CONCLUSIONS 2• - The carbon isotope composition (δ13C) of fine detritus

composed mainly of Sphagnum is temperature (climatically) sensitive while in the higher plants (wood relics) no such effect can be observed.

• - According to obtained results we can conclude that about 8,500 years ago at Bevški mah (300 m) the climate was similar to that presently at the altitude of 300 m a.s.l., but 2,500 years B.P. it should have been much colder, such as currently is at the altitude of about 1,200 m.

• - Therefore, the isotope composition of carbon in Sphagnum relics in peat can be used as an indicator, at least for the Holocene climate changes in this region.

9 Jože Pezdič et al.: 11th IPS, Quebec 2000

10 Jože Pezdič et al.: 11th IPS, Quebec 2000

THANK YOU FOR YOUR ATTENTION!

Jože PEZDIČ, Slovenia

Flood at Ljubljansko barje