Methane emissions and δ 13C composition from beef steers consuming increasing proportions of sericea lespedeza hay on bermudagrass hay diets

An experiment was conducted to evaluate the effects of different proportions of ‘Au Grazer’ sericea lespedeza [SL, Lespedeza cuneata (Dum. Cours.) G. Don], a legume rich in condensed tannins (CT), on nutrient intake and digestibility, and to estimate methane (CH4) emissions and 13C isotopic composition (δ 13CCH4) from beef steers consuming a forage-based diet. Twenty-five Angus-crossbred steers were distributed in a randomized complete block design (344 ± 48 kg initial BW), and randomly assigned to one of five treatments: 0SL, 25SL, 50SL, 75SL, and 100SL, diets containing 0, 25, 50, 75 and 100% of SL hay, respectively, mixed with ‘Tifton-85’ bermudagrass hay (Cynodon spp.). The study was carried out for two experimental periods of 21-d each. The statistical model included the fixed effect of treatment and random effects of block, experimental period, and their interaction. Apparent total tract digestibility of crude protein, neutral detergent fiber, and acid detergent fiber were linearly decreased (P < 0.001) by the inclusion of SL. No effects were observed for total CH4 emissions per day, nor for CH4 relative to organic matter intake or digestible organic matter with the inclusion of SL. However, emission of CH4 in relation to intake of CT was affected by treatment (P < 0.001). A linear (P < 0.001) decrease and a quadratic effect (P < 0.001) were observed for δ 13C of diets and gas, respectively, in which diets and enteric CH4 with greater inclusion of SL were more depleted in 13C. Moreover, the difference in δ 13C between diets and gas (Δδ 13C) had a linear decrease (P = 0.001) with the inclusion of SL. The model developed to predict the C3 proportions in the enteric CH4 fitted to predicted values (P < 0.0001). Therefore, greater proportions of SL resulted in lesser CH4 emission when CT intake was considered and the isotopic composition from enteric CH4 was able to predict the contribution of SL in the emissions.

Monterey Excursion Events in the Middle Miocene Carbonate Rock Succession, Eastern Iraq

The global Monterey excursions are recognized in many deep-sea, and recently in shallow water depth records during the Miocene epoch. We analyzed the δ 13C and δ 18O to investigate the relationship between the lithostratigraphic units and the deviation of the stable isotopes. The results show that there is a significant relationship between the depositional energy changes and both of δ 13C and δ 18O. The present paper is deals with variability of the primary isotopic composition of seawater in the shallow water zone. Sedimentary successions of middle Miocene outcropping in the eastern part of Iraq provide an excellent archive of the oxygen isotope events (Mi‐events), additional details about Mi 2 and Mi 3 zones of glaciations and refine the Monterey Excursion, carbonate isotope maxima (CM‐events). Facies analysis revealed several microfacies could be distinguished, reflecting depositional environments including; lagoon, back reef-reef, shallow open marine, and shoal environments. The Jeribe Formation is a transgression unit belonging to the stage Ap11 tectonostratigraphy Megasequence. The Formation was deposited in the outer platform margin of unstable shelf of the Arabian Plate and significant of this formation, which is deposited during the final phase of Tethys sea closure. The stable isotope (18O/16O and 13C/12C) provide an excellent archive of the paleoceanography for the Neogene (middle Miocene Transgression) of the Neo-Teythys. Oxygen and carbon isotopic stratigraphy for bulk-rock were analyzed in order to distinguished Monterey Event and climate optima.

Effects of nitrogen addition and mowing on nitrogen- and water-use efficiency of Artemisia frigida in a grassland restored from an abandoned cropland

Aims Competition among plants in a community usually depends on their nitrogen (N) use efficiency (NUE) and water use efficiency (WUE) in arid and semi-arid regions. Artemisia frigida is an indicator species in heavily degraded grassland, however, how its NUE and WUE respond to N addition in different successional stages is still unclear, especially with mowing, a common management practice in semi-arid grasslands. Methods Based on a long term controlled experiment with N addition and mowing in an abandoned cropland from 2006 to 2013, we investigated the NUE and WUE of A. frigida in two patches (i.e., grass and herb patches) in 2013 which represented two potential successional stages from herb to grass communities. The coverage of A. frigida was higher (about 50%) in the herb patch than in the grass patch (about 10%). Stable isotopic C (δ 13C) and N (δ 15N) as well as C and N pools were measured in plants and soils. NUE was calculated as leaf C/N, and leaf δ 13C values were used as a proxy for WUE. Important findings N addition did not affect WUE of A. frigida, but significantly decreased NUE by 42.9% and 26.6% in grass and herb patches, respectively. The response of NUE to N addition was related to altering utilization of different N sources (NH4 +vs NO3 -) by A. frigida according to the changed relationship between leaf δ 15N/soil δ 15N and NUE. Mowing had no effect on NUE regardless of N addition, but significantly increased WUE by 2.3% for A. frigida without N addition in the grass patch. The addition of N reduced the positive effect of mowing on its WUE in grass patch. Our results suggested that decreased NUE and/or WUE of A. frigida under mowing and N addition could reduce its competition, and further accelerate restoration succession from the abandoned cropland to natural grassland in the semi-arid region.

Lithological and isotopic (δ 13C and δ 18O) features of the Upper Silurian back-reef lagoon deposits of the Ilych River Basin, the Northern Urals

The Upper Silurian is widely developed in the Northern Urals, where it is represented by various facies. The continental slope facies and the reef shoal facies are well documented in the geological literature, while as back-reef lagoon facies have not yet been characterized in detail. The studied objects included two sections of the back-reef deposits in the Ilych River basin. In this work, we characterize rock types the make up the sections, and their isotopic characteristics. The Late Silurian back-reef lagoon was characterized by a mosaic sediments distribution, which included the island areas between which there were areas with a quiet hydrodynamic regime. In the latter, mainly muddy carbonates were accumulated, represented by clotted fenestral limestones. The area of small islands was characterized by a wide distribution of lime sands, which clastic material was derived from probable paleosoil carbonates. They are characterized by slightly increased δ 13C values, which, probably, reflects isotopic fractionation at the evaporative geochemical barrier. Dolomitization and karstification are described among secondary alterations in the studied sections. Cementstones is interpreted as karst cavities precipitates.

Le passage cénomanien-turonien dans les Monts des Ksour (Atlas Saharien Occidental, Algérie): biostratigraphie, géochimie et milieux de dépôt

[fr] Dans les Monts des Ksour (Atlas saharien occidental), le passage cénomanien-turonien a été étudié sur le plan stratigraphique et géochimique à partir de deux coupes: Djebel M’daouer et Chebket Tamednaïa. Dans ces deux coupes, comme sur la plupart des plates-formes carbonatées peu profondes du domaine sud-téthysien, le faciès anoxique de la limite cénomanien-turonien matérialisé par des dépôts de “black-shales“ est absent. En plus, la rareté des données biostratigraphiques rend difficile l’établissement d’une biozonation détaillée pour les deux coupes étudiées. Les deux seuls niveaux à rares ammonites de la Formation de Ghoundjaïa dans la coupe de M’daouer ont permis de caractériser les zones à Vibrayeanus, à Gamai et à Cauvini. Donc pour les deux coupes, il parait utile de recourir à l’étude isotopique qui a montré une zone d’excursion positive du δ 13C s’étalant le long du Membre inférieur et la partie inférieure du Membre médian de la Formation de Ghoundjaïa. Cette zone d’anomalie est manifestée par trois pics marquants et caractéristiques du passage cénomanien-turonien et la limite entre ces deux étages se situe entre les pics 2 et 3 coïncidant avec le passage de la zone Gamai à la zone Cauvini. L’enregistrement de ces trois pics a rendu possible la corrélation locale de la coupe de Tamednaïa qui est dépourvue de faune valable sur le plan biostratigraphique.

Unexpectedly low δ 13C in leaves, branches, stems, and roots of three acacia species growing in hyper-arid environments

Aims In plant eco-physiology, less negative (enriched) carbon 13 ( 13C) in the leaves indicates conditions of reducing leaf gas exchange through stomata, e.g. under drought. In addition, 13C is expected to be less negative in non-photosynthetic tissues as compared with leaves. However, these relationships in δ 13C from leaves (photosynthetic organs) to branches, stems and roots (non- photosynthetic organs) are rarely tested across multiple closely related tree species, multiple compartments, or in trees growing under extreme heat and drought. Methods We measured leaf-to-root 13C in three closely related desert acacia species (Acacia tortilis, A. raddiana, A. pachyceras). We measured δ 13C in leaf tissues from mature trees in Southern Israel. In parallel, a 7-year irrigation experiment with 0.5, 1.0, or 4.0 L plant -1 day -1 was conducted in an experimental orchard. At the end of the experiment, growth parameters and δ 13C were measured in leaves, branches, stems, and roots. Important findings The δ 13C in leaf tissues sampled from mature trees was ca. -27 ‰, far more depleted than expected from a desert tree growing in one of the Earth’s driest and hottest environments. Across acacia species and compartments, δ 13C was not enriched at all irrigation levels (-28‰ to ca. -27‰), confirming our measurements in the mature trees. Among compartments, leaf δ 13C was unexpectedly similar to branch and root δ 13C, and surprisingly, even less negative than stem δ 13C. The highly depleted leaf δ 13C suggests that these trees have high stomatal gas exchange, despite growing in extremely dry habitats. The lack of δ 13C enrichment in non-photosynthetic tissues might be related to the seasonal coupling of growth of leaves and heterotrophic tissues.

Developing an authentication approach using SPME-GC-IRMS based on compound-specific δ 13C analysis of six typical volatiles in wine

An analytical method using gas chromatography isotope ratio mass spectrometry (GC-IRMS) combined with solid phase micro-extraction (SPME) was developed to measure the δ 13C values of six typical volatiles commonly occurring in wine (isoamyl acetate, 2-octanone, limonene, 2-phenylethanol, ethyl octanoate and ethyl decanoate) for the first time. SPME selected with a divinylbenzene/carboxen/polydimethylsiloxane fiber was combined with the GC-IRMS for pretreatment optimization. The optimized SPME parameters of extraction time, extraction temperature and salt concentration were 40 min, 40 °C and 10 %, respectively. The δ 13C values measured by SPME-GC-IRMS were in good agreement with those measured via elemental analyzer (EA)-IRMS and GC-IRMS. The differences range from 0.02 to 0.44 ‰ with EA-IRMS and from 0 to 0.28 ‰ with GC-IRMS, indicating the high accuracy of the method. This newly established method measured the precision within 0.30 ‰ and was successfully validated to discriminate imported real wine samples with identical label but amazing price difference from different importers.