نتایج جستجو برای: carbon isotope discrimination
تعداد نتایج: 371542 فیلتر نتایج به سال:
During the Miocene prominent oxygen isotope events (Mi-events) reflect major changes in glaciation, while carbonate isotope maxima (CM-events) reflect changes in organic carbon burial, particularly during the Monterey carbon isotope excursion. However, despite their importance to the global climate history they have never been recorded in shallow marine carbonate successions. The Decontra secti...
carbon and sulfur isotopic data are helpful in understanding environmental conditions under which soils are formed. soils from 18 sampling sites along a climotoposequence from higher laleh zar mountains (4,351 m above sea level with xeric-mesic soil moisture-temperature regimes) to shahdad depression (250 m above sea level with arid-hyperthermic soil moisture-temperature regimes) in kerman prov...
Stable isotope analysis of sedimentary carbon in lakes can help reveal changes in terrestrial and aquatic carbon cycles. A method based on a single, photosynthetic organism, where host effects are minimised, should offer more precision than carbon isotope studies of bulk lake sediments. Here we report the development of a systematic method for use on fossil lacustrine diatom frustules, adapted ...
A study was conducted to differentiate lard, chicken fat, beef fat and mutton fat using Gas Chromatography Mass Spectrometry (GC-MS) and Elemental Analyzer-Isotope Ratio Mass Spectrometry (EA-IRMS). The comparison of overall fatty acid data showed that lard and chicken fat share common characteristics by having palmitic, oleic and linoleic acid as major fatty acids while beef and mutton fats sh...
Elevated CO₂ increases intrinsic water use efficiency (WUE(i) ) of forests, but the magnitude of this effect and its interaction with climate is still poorly understood. We combined tree ring analysis with isotope measurements at three Free Air CO₂ Enrichment (FACE, POP-EUROFACE, in Italy; Duke FACE in North Carolina and ORNL in Tennessee, USA) sites, to cover the entire life of the trees. We u...
The occurrence and abundance of microbial fatty acids have been used for the identification of microorganisms in microbial communities. However, these fatty acids can also be used as indicators of substrate usage. For this, a systematic investigation of the discrimination of the stable carbon isotopes by different microorganisms is necessary. We grew 11 strains representing major bacterial and ...
Plants adopt ecological strategy to resist environmental changes and increase their resource-use efficiency. The ecological strategy includes changes in physiological traits and leaf morphology, which may result in simultaneous variations in foliar N concentration and the ratio of intercellular CO2 concentration to ambient CO2 concentration (ci/ca). This in turn links to foliar carbon isotope d...
Questions of biotic and environmental change during deposition of the Upper Maastrichtian Hell Creek Formation require a robust and replicable system for intraformational correlation of fossil localities. In this paper, we present a carbon isotope chemostratigraphic curve based on terrestrial organic carbon. Data were taken from a complete measured section spanning the full 93 m of the Hell Cre...
Stable isotope analysis has been used as a technique to analyse fisheries food webs for a quarter of a century, and remains the principal method for determining energy and nutrient pathways from primary producers to consumers in aquatic ecosystems. Carbon isotope analysis has been used to distinguish autotrophs at the base of inshore and offshore fisheries food webs. The combination of nitrogen...
Fluxes and concentrations of carbon dioxide and 13 CO 2 provide information about ecosystem physiological processes and their response to environmental variation. The biophysical model, CANOAK, was adapted to compute concentration profiles and fluxes of 13 CO 2 within and above a temperate deciduous forest (Walker Branch Watershed, Tennessee, USA). Modifications to the model are described and t...
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