The meeting, hosted by Thomas Rigaudier and Aurélie Noret, was attended by some 25 participants, mainly representatives of platforms affiliated to the Spectrométrie Stables network, as well as a number of CEREGE students and researchers keen to find out more about the network's scientific and technical activities.

In addition to Aurélie Noret, several Panoply members took part in the event.

Read the entire article on RéGEF website.

A new instrument has joined LSCE's organic geochemistry platform.

The project named CGéant (Chromatographie en phase Gazeuse pour l'Etude des Archives Naturelles et anThropiques) aimed at acquiring a GC-FID and a gas generator was co-financed by DIM-PAMIR, RéGEF's GEOF instrument-network and ANR EGOUT project. GEOF co-financed 30% of the new GC- FID. In a move to reduce the environmental footprint of our activities, we purchased reconditioned equipment. In the same vein, we recommissioned an H₂ generator for use as a carrier gas and to power the FID of two instruments: the new GC-FID and a GC-preparative.

Figure : THe GC-FID and  H₂ generator

The GC-FID was the missing link in LSCE's organic geochemistry technical platform, enabling us to rapidly detect and quantify lipids from the various archaeological and environmental matrices we study at LSCE. This makes it possible to identify samples requiring additional molecular analysis, such as structural analysis by GC-MS (mass spectrometry), isotopic analysis by GC-IRMS (isotope ratio mass spectrometry) on δ¹³C and δ²H, and to adapt concentrations to instrument capacity, thus extending the life of consumables. It can also be used to quantify GC-preparative isolation yields when developing new molecules for ¹⁴C measurement by AMS (accelerator mass spectrometry).

Contact: emmanuelle.casanova[a]lsce.ipsl.fr

Figure : δ18O temperature and 15Nexcess temperature reconstructions (this study). Error shading is the same as in Fig. 9. (b) Southern Annual Mode (SAM) annual reconstruction (Dätwyler et al., 2018). The annual resolution of the SAM index is represented by thin lines, and thick lines are the 30-year average for both δ18O temperature and SAM; 15N-excess temperature has a resolution of about 45 years. Yellow shading highlights the 1000–1400 CE period during which the 15N-excess temperature is significantly colder, in phase with a positive SAM index.

Reference: Servettaz, A. P. M., Orsi, A. J., Curran, M. A. J., Moy, A. D., Landais, A., McConnell, J. R., Popp, T. J., Le Meur, E., Faïn, X., and Chappellaz, J., 2023. A 2000-year temperature reconstruction on the East Antarctic plateau from argon–nitrogen and water stable isotopes in the Aurora Basin North ice core. Clim. Past, 19, 1125–1152, https://doi.org/10.5194/cp-19-1125-2023

Figure : Age against depth for the Skytrain Ice Rise ice core. In the top panel, ice and air age are shown, along with the tie points we applied. The turquoise line shows the uncertainty on the ice age derived from Paleochrono, using the right hand y axis. The section with unreliable ages (605–617 m) is greyed out, and the uncertainties around this section are probably underestimated.

Reference: Mulvaney, R., Wolff, E. W., Grieman, M. M., Hoffmann, H. H., Humby, J. D., Nehrbass-Ahles, C., Rhodes, R. H., Rowell, I. F., Parrenin, F., Schmidely, L., Fischer, H., Stocker, T. F., Christl, M., Muscheler, R., Landais, A., and Prié, F., 2023. The ST22 chronology for the Skytrain Ice Rise ice core – Part 2: An age model to the last interglacial and disturbed deep stratigraphy. Clim. Past, 19, 851–864, https://doi.org/10.5194/cp-19-851-2023.

Fig. 1. Coral skeletal composition. (A)  B/Ca and (B) δ11B values of Porites (n = 33, blue) & Diploastrea (n = 6, red) corals across the Pacific Ocean plotted against SST. (C-F) Carbonate chemistry variables of calcifying fluid calculated for each colony (DICcf, pHcf, [CO32-]cf, Ωcf, respectively) against SST. The filled blue and red dots represent the 6 sites where both Porites and Diploastrea were sampled.

At the basin scale of the Pacific Ocean, we show that both genera systematically up-regulate their calcifying fluid pH and dissolved inorganic carbon to achieve efficient skeletal precipitation. However, while Porites corals increase the aragonite saturation state of the calcifying fluid (Ωcf) at higher temperatures to enhance its calcification capacity, Diploastrea shows a steady homeostatic Ωcf across the Pacific temperature gradient. Thus, the extent to which Diploastrea responds to ocean warming and/or acidification is unclear, and it deserves further attention whether this is beneficial or detrimental to future survival of this coral genus.

Fig. 2. Correlations between SST & calcifying fluid composition in co-occurring Porites (n = 6, blue dots) and Diploastrea (n = 6, red dots) specimens across the Pacific Ocean. Solid blue and red lines in the left panels indicate significant correlations.

Reference: Marine Canesi, E. Douville, P. Montagna, M. Taviani, J. Stolarski, L. Bordier, A. Dapoigny, G. E. H. Coulibaly, A.-C. Simon, M. Agelou, J. Fin, N. Metzl, G. Iwankow, D. Allemand, S. Planes, C. Moulin, F. Lombard, G. Bourdin, R. Troublé, S. Agostini, B. Banaigs, E. Boissin, E. Boss, C. Bowler, C. de Vargas, M. Flores, D. Forcioli, P. Furla, E. Gilson, P. E. Galand, S. Pesant, S. Sunagawa, O. Thomas, R. Vega Thurber, C. R. Voolstra, P. Wincker, D. Zoccola, S. Reynaud (2023). Differences in carbonate chemistry up-regulation of long-lived reef-building corals. Scientific Report, 41598. DOI : 10.1038/s41598-023-37598-9

Notre-Dame de Paris, the so famous Catholic cathedral standing on Ile de la Cité in Paris, was built in 1163, largely completed by 1260, then frequently modified in the following centuries until a major restoration between 1844 and 1864. All these steps of construction and modifications involved the frame, so-called “la forêt” (the forest). So, the woods used throughout the cathedral’s history are samples and memories of the forests of oaks grown in the Paris Basin since the Middle Ages. The unfortunate destruction of the cathedral on 15th April of 2019, which miraculously spared a part of the frame, made these woods accessible to the scientific community. Some scientists are particularly interested in the isotopic composition of wood as memory of past climate and as a clock to the past. On one part, the oxygen and carbon isotopes (d13C and d18O) of tree-ring cellulose will bring light to past climate. Indeed, the isotopic composition of this component is determined by the conditions surrounding the trees during their growth. The variations of d13C and d18O with time, recorded in the successive rings built by the trees year after year, allows reconstructing the evolution of some environmental or climatic parameters such as temperature or humidity. Isotope dendroclimatology, a rapidly expanding field of investigation, is applied to old living trees, sub-fossil woods from buildings or even fossil material to reconstruct past climate. This methodological approach will be applied to the cathedral's oak timbers that have escaped severe charring and to contemporaneous unburned woods from other buildings (Figure 1). On the other part, measuring ring by ring the residual content of 14C isotope in cellulose will make it possible to refine the 14C clock which allows to date any material containing carbon. This will be achieved by providing new portions of the global calibration curve for the continental Western Europe from the 12th to the 18th century, from uncharred "forest" of Notre-Dame.

Figure 1: Modus Operandi we will follow to reconstruct past climate and past atmospheric ¹⁴C records at annual scale. ¹⁴C record is expected to complete the next ¹⁴C calibration curve and perhaps to highlight past solar events.

Reference: Daux V., Hatté C., duBoisgueheneuc D., Beck L., Richardin P. The ‘forest’ of Notre dame de Paris: a path into medieval climate and time. Journal of Cultural Heritage, In press