Diapositive 1

1
RECIPE meeting May 17-20Th Munich,GERMANY
Laure Comont, Fatima Laggoun-Défarge, Jean-Robert
Disnar Pascale Gautret, Nathalie Lottier,
Marielle Hatton, Li Huang
Earth Science Institute of Orleans ,
France Group  Organic Matter in water, sols,
sediments and rocks  
2
WP5 work progress since Carentan meeting
I Exploration of physico-chemical data (PCA) on
peat OM from the five studied sites (WP01)
(correlations between C, N, organic constituent
countings sugar analyses in both bulk peat and
fine-grained fraction)
II- Sugar analyses on the bulk peat compared to
the fine-grained fraction (Le Russey sites on FRC
FRD) gt identification of
biomarkers (OM degradation processes)
III- Tests of aminoacid analyses on 2 samples
from CH (solid and soluble fractions) gt
interesting preliminary results obtained for
identification of neoformation markers gt results
are correlated with cryo-scanning electron
microscopy (cryo-SEM) observations

• IV Microtexture of peat (2 distinct scales)
• cryo-SEM
• X-ray computed tomography

3
I DETERMINATION OF VARIOUS CORRELATIONS
4
Principal component analyses (PCA)
5
Principal component analyses (PCA)
Schematic model of peat evolution

• Similar evolution at 1st steps of regen. for
  Jura Scotish sites
• gt similar plant compositions of new peat
  (mainly Sphagna)

• Distinct evolution for FI
• gt the composition of  litter  from
  Finish sites is quite different
• (C.rostrata, E.vaginatum)

- The old peat evolution of SC FI sites
converge with the same variables which
characterise a more humified peat
6
II - SUGAR ANALYSES ON BULK PEAT (comparison with
fine-grained fractions) LE RUSSEY FRC (2nd
regeneration stage) FRD (intact area)
7
Sugar analyses on the BULK peat (compared to the
FINE fraction lt200µm)
Le Russey FRC,2nd regen.stage

• Total sugar contents (mg/g)
• Bulk 432 (top) gt 137 (bottom)
• Fine 206 (top) gt 80 (bottom)

sugars derived from inherited plants tissues
(Tot. Cell., Ara Xyl)
- High sugars decrease well correlated with
fine-grained fraction increase
- Tot.Hem.sugars increase well correlated with
of Muc.
-progressive Hem.Gluc. increase is certainly due
to cellulose destructuration
- High difference, between both fractions, of
Rham Rib (relative )
8
Sugar analyses on the BULK peat (compared to the
FINE fraction lt200µm)
Le Russey FRD intact area

• Total sugar contents (mg/g)
• Bulk 295 (top) gt 170 (bottom)
• Fine 227 (top) gt 125 (bottom)

sugars derived from inherited plants tissues
(Tot. Cell., Ara Xyl)
- Progressive decrease of sugars (compared to
FRC) no correlation with fine fraction
- increase at depth corresponding to preservation
processes
- Less contrast between bulk and fine peats
compared to FRC

• progressive increase of H. cell. Glucose

9
Sugar analyses, preliminary conclusions
FRD
FRC
I-surface
Tot. Sugars high degradation Bulk 432 (top) gt
137 (bottom) Fine 206 (top) gt 80 (bottom)
Tot. Sugars low degradation Bulk 295 (top) gt
170 (bottom) Fine 227 (top) gt 125 (bottom)
II-depth
Higher contribution of Rib in the fine-grained
fraction gt Degradation?
High Cellulosic sugars, Xyl in the bulk
fraction gt Primary input preservation
- Surface processes evolution kinetics strongly
differ in the  new  regenerating peat and in
the intact peat.
10
III - AMINOACID ANALYSES LA CHAUX DABEL FEN
SITUATION CHA43 CHA73
11
Aminoacid analyses, experiment
Acid hydrolysis
HPLC
quantification distribution of AA
12
Chaux dAbel, CHA situation, aminoacid results
- 2 compartments soluble and solid fractions
13
Chaux dAbel, CHA situation, aminoacid results
Example chrommatogram of level 4 (5-10 cm)
14
Chaux dAbel, CHA situation, aminoacid results
Hydrolysable AA YIELD (mg/g) or (mg/l)

• 96 of free NH3
• 42 of Gly

gt 20 of Gly
At 5-10 cm (regenerated peat) high diminution of
total AA compared to living plants gt
degradation of plant proteins in this level.
Thats confirmed by the total AA quantity in
soluble fraction.
At 35 cm (old peat) amounts of AA are 20 times
higher than those at the surface and also higher
than those of living plants.
gt 2 hypotheses - important and widespread
microbial population (either active or dead) ?
to
be correlated with microbial groups WP03
- selective preservation of
some plant proteins and accumulation due to
specific environmental conditions ?
15
Chaux dAbel, CHA situation, aminoacid results
Microbial production or selective preservation ?
Munich progress meeting May 17-20th
16
Chaux dAbel, sugar results on soluble fraction
Microbial production or selective preservation ?

• Higher Total sugar contents in the soluble
  fraction at depth than at the sub-surface (level
  7 vs. 4)
• are these soluble compounds autochthonous or not
  (i.e. brought by diffusion from the surface or
  elsewhere)

Munich progress meeting May 17-20th
17
Cryo-scanning electron microscope (cryo-SEM)
Microbial production or selective preservation ?
The cryo-SEM is equipped with a freeze-drying
sample preparation system. It allows studing the
composition and the micromorphology of hydrous
materiel (peat) and spatial relationships between
organic components.
Tests were carried out on samples from Le Russey
site
18
The cryo-SEM, results, FRC 2nd regeneration stage
Microbial production or selective preservation ?
level 3
Microorganisms inside well-preserved cell walls
Cross section of Sphagna steam
3D polysaccharidic network
19
Preliminary conclusions
distinct degradation processes between these 2
peat samples
2 processes are determined - Selective
preservation
- Microbial production Which of these 2
processes is dominant ?
20
IV PHYSICAL MICROTEXTURE OF THE PEAT
21
Physical microtexture of the peat
distinct µmorphologies in the bare peat the
transition  old / new  peat
I- Cryo-SEM observations
level 3
level 5
bare peat, FRA
2nd reg. stage, FRC
more compact, dense peat
analyses are in progress
22
Conclusions

• Association of AA analyses sugar analyses in
  soluble fraction
• gt interesting approach to better identify the
  markers of OM degradation
• to be applied in WPO2

• Exploration of physico-chemical data (PCA) on
  peat OM from the five sites (WP01)
• gt distinct evolution trends for Jura peatlands
  and SC/FI peatlands gt climatic
  influence ? Initial vegetation types ?

• 2 important problems arise
• gt datations of both new peat horizons
  and transitional peat layer
• gt insufficient numbers of peat samples
  along the profiles of the new
  regenerating horizon (only 2 to 3)
• For WPO2 gt adopt a better strategy of
  sampling !!!!!