INRA Nancy, UMR Écologie et Écophysiologie, 54280 Champenoux, France
(Received 24 April 2006; accepted 30 June 2006)
Abstract – We characterised the among species variability in leaf gas exchange and morphological traits under controlled conditions of seedlings of
22 tropical rainforest canopy species to understand the origin of the variability in leaf carbonisotope discrimination ( ∆) among species with diﬀerent growth and dynamic characteristics (successional gradient). Our results first suggest that these species pursue a consistent strategy in terms of ∆ throughout their ontogeny (juveniles grown here versus canopy adult trees from the natural forest). Second, leaf ∆ was negatively correlated with WUE and N, and positively correlated with g s , but among species di ﬀerences in ∆ were mainly explained by diﬀerences in WUE. Finally, species belonging
The IRMS instrument is located at the Center for Isotopic Research for Cultural and Environ- mental heritage (CIRCE). This work is a part of the “Advanced Laser techniques to Investigate CarbonisotopE discrimination during decomposition” (ALICE) project funded by the European Union through the Marie Curie Actions for Transfert of Knowledge (Contract MTK–CT–2004– 014532). We also acknowledge the two anonymous reviewers for their expertise and useful
We found a regional trend in carbonisotope ratios, with the δ 13
C in Calling Lake > Drayton Valley > Lac Duparquet, both before and after VRH (Figure 1). Increased mean annual pre- cipitation and relative humidity, and lower mean daily vapor pressure deficit from Calling Lake to Lac Duparquet (Table 1), appeared to be associated with a reduction in regional mean tree water stress and increased site productivity, as reflected in mean tree height, diameter and crown volume (Table 2). This supports the notion that regional hydro-climate governs grow- ing season stress and forest productivity (Grier and Running 1977, Kergoat 1998). These results also indicate that water stress following VRH is potentially a greater concern in more xeric regions, where trees may already be showing signs of at- mospheric water stress before harvest, than in moister regions. However, caution may be necessary in interpreting the link between precipitation and wood δ 13 C. In a study of Eucalyptus species, Schulze et al. (2006) found that specific leaf area or soil water-holding capacity explained a greater proportion of the variability in δ 13 C than precipitation. Nevertheless, given the large number of replications and several lines of evidence depicted in Figures 1 and 2, we maintain that it is likely that the stress we identified by the analysis of δ 13 C in wood is related to the new stresses imposed by VRH and differences in regional climate.
University, New Brunswick, New Jersey, USA
Abstract The carbonisotope composition ( δ 13 C) of seawater provides valuable insight on ocean circulation, air-sea exchange, the biological pump, and the global carbon cycle and is re ﬂected by the δ 13 C of foraminifera tests. Here more than 1700 δ 13 C observations of the benthic foraminifera genus Cibicides from late Holocene sediments ( δ 13 C Cibnat ) are compiled and compared with newly updated estimates of the natural (preindustrial) water column δ 13 C of dissolved inorganic carbon ( δ 13 C DICnat ) as part of the international Ocean Circulation and Carbon Cycling (OC3) project. Using selection criteria based on the spatial distance between samples, we ﬁnd high correlation between δ 13 C Cibnat and δ 13 C DICnat , con ﬁrming earlier work. Regression analyses indicate signi ﬁcant carbonate ion (2.6 ± 0.4) × 10 3 ‰/(μmol kg 1 ) [CO 3 2 ] and pressure ( 4.9 ± 1.7) × 10 5 ‰ m 1 (depth) effects, which we use to propose a new global calibration for predicting δ 13 C DICnat from δ 13 C Cibnat . This calibration is shown to remove some systematic regional biases and decrease errors compared with the one-to-one relationship ( δ 13 C DICnat = δ 13 C Cibnat ). However, these effects and the error reductions are relatively small, which suggests that most conclusions from previous studies using a one-to-one relationship remain robust. The remaining standard error of the regression is generally σ ≅ 0.25‰, with larger values found in the southeast Atlantic and Antarctic (σ ≅ 0.4‰) and for species other than Cibicides wuellerstor ﬁ. Discussion of species effects and possible sources of the remaining errors may aid future attempts to improve the use of the benthic δ 13 C record.
Mots clés : discrimination isotopique du carbone, sécheresse, sénescence, blé dur (Triticum durum Desf.)
Abstract: The relationships between leaf senescence, carbonisotope discrimination and yield performance were
examined in durum wheat (Triticum durum Desf.), in the high plains of Setif, eastern Algeria. Ten CIMMYT high- yielding cultivars were grown during two cropping seasons characterized by low rainfall (217 and 162 mm, respectively), freezing temperatures at heading stage and terminal heat stress. Senescence was assessed using numerical image analysis (NIA). Carbonisotope discrimination was analyzed in flag leaves at anthesis and grain at maturity. Senescence was significantly negatively correlated to grain yield in season 1, but not in season 2. There was no relationship between Δ and grain yield in both seasons. The absence of association between Δ and grain yield is likely to be due a strong contribution of pre-anthesis assimilates to yield together with a sink limitation of yield.
rable, de l’Environnement et de la Lutte contre les Changements Climatiques is gratefully acknowledged.
Conrad, R., Claus, P., Chidthaisong, A., Lu, Y., Fernandez Scavino, A., Liu, Y., Angel, R., Galand, P. E., Casper, P., Guerin, F. & Enrich-Prast, A. (2014) Stable carbonisotope biogeochemistry of propionate and acetate in methanogenic soils and lake sediments. Organic Geochemistry 73, 1-7.
Proof For Review
Carbonisotope values (‰ VPDB) of the Porto Rico and El Argoub sections, compared to δ13Ccurves around the Eocene-Oligocene transition in ODP Site 1218 (Erhardt et al., 2013) and reference δ13C composite curve (Cramer et al., 2009 modified by Vandenberghe et al., 2012). EOT=Eocene-Oligocene Transition; U1 to U5
Résumé – Multiples excursions isotopiques du carbone de l’Eocène inférieur associées à des changements environnementaux dans le Bassin de Dieppe-Hampshire (Europe du NO). L ’Eocène inférieur fût le théâtre d’une série de réchauffements climatiques rapides et globaux nommés hyperthermaux qui sont associés à des excursions isotopiques négatives du carbone (CIE = CarbonIsotope Excursion). Le maximum thermique du Paléocène-Eocène (PETM = Paleocene-Eocene Thermal Maximum ou ETM- 1 = Eocene Thermal Maximum-1) et le Maximum Thermique de l’Eocène-2 (ETM-2) sont les deux évènements principaux de cette Epoque et sont tous les deux marqués par la dissolution massive de carbonates des fonds marins. Leurs timings, amplitudes et impacts sont plutôt bien documentés, mais des CIEs de plus faible amplitude, également associées à des dissolutions de carbonates, sont encore peu étudiées (p. ex. évènements E1 à H1), notamment dans le domaine continental où les hiatus/inconformités ainsi que les taux de sédimentation variables dans une même succession compliquent l’identiﬁcation des évènements isotopiques globaux. Ici, nous présentons une nouvelle étude « multi-proxy » à haute résolution sur la succession continentale, lagunaire et marine peu profonde de deux sites du secteur du Cap d’Ailly dans le Bassin de Dieppe-Hampshire (Normandie). Les données isotopiques du carbone ( d 13 C) de la matière organique totale et des n-alcanes de végétaux supérieurs ainsi que les âges K-Ar de glauconies authigènes ont été déterminés pour obtenir un cadre stratigraphique robuste. Les palynofaciès ainsi que la distribution et les données isotopiques de l’hydrogène (d 2
carbonisotope maxima (the so-called CM events) related to changes in marine export productivity? Here we use benthic foraminiferal accumulation rates from three sites in the Paci ﬁc and Southern Oceans and a geochemical box model to assess relationships between benthic foraminiferal δ 13 C records, export productivity, and the global carbon cycle. Results from Deep Sea Drilling Project Hole 588 and Ocean Drilling Program Site 747 show a distinct productivity maximum during CM 6 at 13.8 Ma, the time of major expansion of ice on Antarctica. Productivity maxima during other CM events are only recorded at high-latitude Site 747. A set of numerical experiments tests whether changes in foraminiferal δ 13 C records (CM events) and export productivity can be simulated solely by sea level ﬂuctuations and the associated changes in global weathering-deposition cycles, by sea level ﬂuctuations plus global climatic cooling, and by sea level ﬂuctuations plus invigorated ocean circulation. Consistent with data, the periodic forcing of sea level and albedo (and associated weathering cycles) produces δ 13 C variations of the correct temporal spacing, albeit with a reduced amplitude. A productivity response of the correct magnitude is achieved by enhancing ocean circulation during cold periods. We suggest that the pacing of middle Miocene δ 13 C ﬂuctuations is associated with cyclical sea level variations. The amplitude, however, is muted perhaps due to the competing effects of a time-lagged response to sea level lowstands but an immediate response to invigorated ocean circulation during cold phases.
heavier carbonisotope ( 13 C), during assimilation
processes, because the process depends on the intercellular and atmospheric carbon dioxide
partial pressure (Pi and Pa). The process could be defined as the ratio of Pi/Pa. Higher Pi/Pa may result in higher CID due to higher the conductance of stomata. Thus, WUE is negatively related to both Pi/Pa and CID (Farquhar, Ehleringer, & Hubick, 1989; Singh & Reddy, 2011). A physiological way can balance breeding method and may improve the proportion of yield enhancement in the following approach. First, high seasonal variability in yield and genotype by environmental interactions will gain stagnant genetic for yield. Second, it could detect the important traits. There is insufficient genetic variability in plant breeders’ populations. Specific aim of morphological and physiological traits that have a high value of heritability and limit yield could be more effective than direct selection for yield (Richards et al., 2010; Richards, Rebetzke, Condon, & van Herwaarden, 2002).
result from a microhabitat differentiation of C. kullenbergi and C. wuellerstor ﬁ, which has been previously proposed [Hodell et al., 2001, 2003a], and/or from variations in the pore water δ 13 C DIC gradient. Even small
microhabitat changes may have a signi ﬁcant inﬂuence on epibenthic foraminifer δ 13 C, because vertical pore water δ 13 C DIC gradients in marine sediments are large and vary depending on organic carbon rain rates and bottom water oxygen concentrations (Figure 6) [McCorkle and Emerson, 1988; McCorkle et al., 1997; Tachikawa and Elder ﬁeld, 2002]. These gradients may reach up to −1‰cm −1 , in particular near the surface [McCorkle et al., 1985], and can be accompanied by pore water carbonate ion variations that may have an additional (potentially counteracting) in ﬂuence on benthic δ 13 C [Spero et al., 1997; Bemis et al., 1998]; however, a carbonate ion-dependent carbonisotope effect on benthic foraminifera remains to be demonstrated and quanti ﬁed. Small increases in the calcite precipitation depth of C. kullenbergi within the sediment may explain the observed glacial δ 13 C Ck-Cw gradient, if the microhabitat of C. wuellerstor ﬁ (s.l.) did not shift simultaneously
The last study in north eastern Algeria on the potential use of carbonisotope discrimination (CID) in wheat selection conducted between 2003-2008 in collaboration with the IAEA showed several facets. Indeed, the results of seven trials in rainfed conditions characterized by a rainfall fluctuating between 250 and 500 mm and by additional
High water use efficiency (WUE) can be achieved by coordination of biomass accumulation and water consumption. WUE is physiologically and genetically linked to carbonisotope discrimination (CID) in leaves of plants. A population of 148 recombinant inbred lines (RILs) of sunflower derived from a cross between XRQ and PSC8 lines was studied to identify quantitative trait loci (QTL) controlling WUE and CID, and to compare QTL associated with these traits in different drought scenarios. We conducted greenhouse experiments in 2011 and 2012 by using 100 balances which provided a daily measurement of water transpired, and we determined WUE, CID, biomass and cumulative water transpired by plants. Wide phenotypic variability, significant genotypic effects, and significant negative correlations between WUE and CID were observed in both experiments. A total of nine QTL controlling WUE and eight controlling CID were identified across the two experiments. A QTL for phenotypic response controlling WUE and CID was also significantly identified. The QTL for WUE were specific to the drought scenarios, whereas the QTL for CID were independent of the drought scenarios and could be found in all the experiments. Our results showed that the stable genomic regions controlling CID were located on the linkage groups 06 and 13 (LG06 and LG13). Three QTL for CID were co-localized with the QTL for WUE, biomass and cumulative water transpired. We found that CID and WUE are highly correlated and have common genetic control. Interestingly, the genetic control of these traits showed an interaction with the environment (between the two drought scenarios and control conditions). Our results open a way for breeding higher WUE by using CID and marker-assisted approaches and therefore help to maintain the stability of sunflower crop production.
A general procedure for the late-stage [ 11 C], [ 13 C] and [ 14 C]carbonisotope labeling of cyclic carbamates is reported. This
protocol allows the incorporation of carbon dioxide, the primary source of carbon-14 and carbon-11 radioisotopes, in a direct, cost-effective and sustainable manner. This method was applied to a variety of carbamates, including pharmaceuticals. A disconnection / reconnection strategy, involving ring opening / isotopic closure, was also implemented to efficiently broaden the approach.
Figure 4: Cu-catalyzed carbon-14 labeling of pharmaceutical relevant molecules. (A) Reaction conditions as follows: 20 mol% catalyst and ligand loading, see supporting information for de- tailed experimental procedures. (B) Comparison with multi step methods previously reported in the literature. The colored circles (dark or light blue) and numbers denote the positions of the car- bon atoms labeled and the percent incorporation of the carbonisotope, respectively. Molar activities for each compound are expressed in MBq mmol -1 .
clearly show the advantages of these CIE methods over traditional multi-step approaches.
In summary, we have highlighted the emerging concept of carbonisotope exchange, which will pave the way to an easier and more sustainable access to molecules labelled with carbon isotopes. There is no doubt that numerous future research works will be dedicated to the discovery of novel CIE reactions in order to broaden the scope of applications and to allow multiple isotope incorporation. Further utility
Recent breakthroughs in late-stage 14 C labeling have challenged this traditional approach and showcased direct access to complex scaffolds from [ 14 C]CO
2 . 10 In addition, the first examples of transition-metal-catalyzed carbonisotope exchange (CIE) have recently emerged. 11 Such technology enable selective replacement of molecular moieties into complex organic molecules, by reversible molecular deconstruction/reconstruction thus providing access to 14 C labeled compounds in a single operation, directly from the end-use molecules. We described a copper-catalyzed decarboxylative-carboxylation of (hetero)aromatic carboxylic acid salts with [ 14 C]CO
and are able to calculate the 𝛿 13 C of the additional CH
4 source in ice core samples. 2.5.3. The Isotopic Fractionation of the Total CH 4 Sink in Keeling Plot Analysis
Literature values of 𝜀 tot vary from −7.7‰ [Lassey et al., 2007] to −5.4‰ [Mischler et al., 2009], while it has been suggested to scale 𝜀 tot to [CH 4 ] on glacial-interglacial timescales [Schaefer and Whiticar, 2008]. The determina- tion of 𝜀 tot depends on the isotope fractionation of the respective CH 4 sinks and their relative contribution to the total sink ﬂuxes. Note that both factors are likely to have varied on glacial-interglacial timescales and that the cumulative eﬀect on 𝜀 tot on glacial timescales is not well understood [e.g., Schaefer and Whiticar, 2008;
δ 13 C-primary producers is not observed. This is likely due to isotopic
fractionation, although additional sources of carbon could also affect this relationship. Previous estimations of isotopic fractionation associated with inorganic carbon uptake are around 12‰ and 20‰ for macrophytes and phytoplankton, respectively (LaZerte and Szalados 1982; Chanton and Lewis 1999). These estimations are in good agreement with the fractionation factors derived in our study by applying the previously described approach (section 4.1.2) to carbon signatures along the salinity gradients (16.7 ± 5.4‰ for macrophytes and 20.6 ± 3.0‰ for phytoplankton in La Palme lagoon; 14.8 ± 6.0‰ for macrophytes and 20.3 ± 3.3‰ for phytoplankton in Salses-Leucate lagoon). Fractionation thus explains the majority of the difference between the carbon signatures of DIC and primary producers and the lack of a 1:1 relationship. Assimilation of atmospheric CO 2 during emersion as additional