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RECIPE meeting May 17-20 Th Munich,GERMANY

RECIPE meeting May 17-20 Th 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  ».

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RECIPE meeting May 17-20 Th Munich,GERMANY

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  1. RECIPEmeeting 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. Munich progress meeting May 17-20th 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) => identification of biomarkers (OM degradation processes) III-Tests of aminoacid analyses on 2 samples from CH (solid and soluble fractions) : => interesting preliminary results obtained for identification of neoformation markers => 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. Munich progress meeting May 17-20th I – DETERMINATION OF VARIOUS CORRELATIONS

  4. CH : 1963 (~40 yrs) and FR : 1984 (~20 yrs) FB (less than 5 yrs ?) FI : 1975 - 1978 (~30 yrs) SC : 2000 (~5 yrs) => 1995 (~10 yrs) => 1955 (~50 yrs) Peat harvesting ended : Munich progress meeting May 17-20th Principal component analyses (PCA)

  5. 3 distinct trends starting • from the « new » regen. peat of all sites: • Jura sites • Scotish sites • Finnish sites Munich progress meeting May 17-20th Principal component analyses (PCA) Schematic model of peat evolution • Similar evolution at 1st steps of regen. for Jura & Scotish sites • => similar plant compositions of new peat (mainly Sphagna) • Distinct evolution for FI • => 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. Munich progress meeting May 17-20th II - SUGAR ANALYSES ON BULK PEAT (comparison with fine-grained fractions) LE RUSSEY FRC (2nd regeneration stage) FRD (intact area)

  7. sugars derived (partly) from microbial syntheses(Hem.Gluc, Fuc, Rham, Man & Rib) Sugar analyses on the BULK peat (compared to the FINE fraction <200µm) Le Russey FRC,2nd regen.stage • Total sugar contents (mg/g): • Bulk ≈ 432 (top) => 137 (bottom) • Fine ≈ 206 (top) => 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. sugars derived (partly) from microbial syntheses(Hem.Gluc, Fuc, Rham, Man & Rib) Sugar analyses on the BULK peat (compared to the FINE fraction <200µm) Le Russey FRD intact area • Total sugar contents (mg/g): • Bulk ≈ 295 (top) => 170 (bottom) • Fine ≈ 227 (top) => 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. Degradation of sugar parallels destructurationof plant tissues Degradation of sugars ≠ destructuration of plant tissues Munich progress meeting May 17-20th Sugar analyses, preliminary conclusions FRD FRC I-surface: Tot. Sugars: high degradation Bulk ≈ 432 (top) => 137 (bottom) Fine ≈ 206 (top) => 80 (bottom) Tot. Sugars: low degradation Bulk ≈ 295 (top) => 170 (bottom) Fine ≈ 227 (top) => 125 (bottom) II-depth: Higher contribution of Rib in the fine-grained fraction => Degradation? High Cellulosic sugars, Xyl in the bulk fraction => Primary input preservation - Surface processes: evolution kinetics strongly differ in the « new » regenerating peat and in the intact peat.

  10. Munich progress meeting May 17-20th III - AMINOACID ANALYSES LA CHAUX D’ABEL FEN SITUATION CHA43 CHA73

  11. Test of identification of total aminoacids: La Chaux d’Abel,fen situation CHA Living plants : Mosses:S.fallax & Polytrichum(steams & rhizoids) Cyperaceae:E.vaginatum(leaves & roots) E.angustifolium 3 4 Solid bulk peat 5 Soluble fraction, ultrafiltration: fraction (>3kDa) F1 fraction (<3kDa) F2 6 7 Solid bulk peat Soluble fraction, ultrafiltration: fraction (>3kDa) F1 fraction (<3kDa) F2 8 peat profil 3kDa ~ 400Å Munich progress meeting May 17-20th Aminoacid analyses, experiment Acid hydrolysis HPLC quantification & distribution of AA

  12. living plants soluble OM peat In soluble fraction: high % of basic AA (Lys & Arg) ➱ Preferential accumulation of basic AA in acidic environment ? ➱ Another source (microorg. groups rich in basic AA)? • Gly: smallest and simplest AA • => index of degradation Munich progress meeting May 17-20th Chaux d’Abel, CHA situation, aminoacid results - 2 compartments: soluble and solid fractions

  13. Solid bulk Solid fraction: All AA are well represented including di-carboxylic AA (Asp, Glu..) Soluble fraction: mainly composed of basic AA (Arg & Lys) + Free ammonia => degradation markers ? ? Non proteinic AA (Orn & unknown peaks) => neosynthetic AA from abiotic or biotic activity soluble (> 3kDa) soluble (< 3kDa) ? ? ? ? Munich progress meeting May 17-20th Chaux d’Abel, CHA situation, aminoacid results Example: chrommatogram of level 4 (5-10 cm)

  14. Munich progress meeting May 17-20th Chaux d’Abel, CHA situation, aminoacid results Hydrolysable AA YIELD (mg/g) or (mg/l) • 96% of free NH3 • 42% of Gly => 20% of Gly At 5-10 cm (regenerated peat): high diminution of total AA compared to living plants => degradation of plant proteins in this level. That’s 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. => 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. Good correlation between peat samples and some living plants Frequency histograms of individual AA examplify these correlations Chaux d’Abel, CHA situation, aminoacid results Microbial production or selective preservation ? Munich progress meeting May 17-20th

  16. level 4 (5-10 cm) level 7 (32,5-37,5 cm) Total sugar contents ≈ 5,5 mg/l 58% of unknowns (neoformed ?) Total sugar contents ≈ 8,3 mg/l 23% of unknowns (neoformed ?) Higher proportions of xylose (glucose?) and fucose at depth => inheritance (xylose?) and/or in situ microbial production (fucose?)? Chaux d’Abel, 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. FRC, 2nd regeneration stage level 3 (0-5 cm) level 5 (12,5 - 17,5 cm) level 8 (42,5 - 47,5 cm) Munich progress meeting May 17-20th 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. 2,3µm 12µm 50µm 3µm 5µm 3µm level 5 level 8 3D polysaccharidic network degraded cell walls Biofilm Eps(extracellular polymer secretion) Bacterial colony 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. Solid fraction Soluble fraction Solid fraction Soluble fraction level 4 : - High living plant proteins degradation in the solid fraction Total AA ≈ 5 µg/mg Total AA ≈ 43,51µg/ml Total AA ≈ 134 µg/mg Total AA ≈ 13,14 µg/ml Total sugars ≈ 5.5 mg/l Total sugars ≈ 8,3 mg/l - High sugars degradation in soluble fraction • - High hydrolysable AA yield in the solid fraction • ≠ materiel sources • lower degradation level 7 : - Higher Tot. sugar contents in the soluble fraction Munich progress meeting May 17-20th 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. FRA, bare peat FRC, 2nd regeneration stage level 3 (0-5 cm) level 3 (0-5 cm) level 5 (12,5 - 17,5 cm) level 8 (42,5 - 47,5 cm) Munich progress meeting May 17-20th IV – PHYSICAL MICROTEXTURE OF THE PEAT

  21. 5µm 5µm II- X-ray computed Tomography : Visualisation of the 3D porous network on different peat types under increasing range of wetness (re-wetting process) Tests carried out on 2 samples (Coll. R. Swennen from Leuven University, Belgium): RyI = FRC level 7-12 cm RyI = FRC level 40-50 cm Munich progress meeting May 17-20th 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. Munich progress meeting May 17-20th Conclusions • Association of AA analyses + sugar analyses in soluble fraction • => 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) • => distinct evolution trends for Jura peatlands and SC/FI peatlands => climatic influence ? Initial vegetation types ? • 2 important problems arise: • => datations of both «new» peat horizons and transitional peat layer • => insufficient numbers of peat samples along the profiles of the new regenerating horizon (only 2 to 3) • For WPO2 => adopt a better strategy of sampling !!!!!

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