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  • Variations
  • In order to get a homogeneous dataset, minimizing variations in the isotopic composition of the material depending on its type and/or depositional environment, we selected only calcareous paleosols sampled in several continuous sections covering a wide time range from the Late Jurassic to the Pliocene. (mdpi.com)
  • Pb isotope variations in igneous and metamorphic crustal rocks define broad spatial patterns that make the Pb signature of detrital K-feldspar grains a useful provenance tool. (geoscienceworld.org)
  • seawater
  • Micro-crystalline barites recovered by deep-sea drilling from Site 684 on the Peru margin and Site 799 in the Japan Sea are highly enriched in the heavy sulfur isotope relative to seawater ( d34S up to +84? (pangaea.de)
  • waters
  • Oxygen isotope compositions of surface waters (delta O-18(w)) estimated from turtle and crocodile delta O-18(p) values range from -5.0 +/- 1.0 parts per thousand to -2.4 +/- 1.0 parts per thousand, which do not differ from mean annual rainwater values occurring today under inter-tropical sub-arid to arid climates. (ipgp.fr)
  • Concentration
  • As a result of variation in environmental factors, such as temperature, precipitation, photosynthetically active radiation, and atmospheric CO 2 concentration along altitudinal gradients, changes in morphological and physiological traits and leaf carbon isotope composition in alpine plants are expected. (hindawi.com)
  • Genetic variation in tree growth and branchlet carbon isotope composition (13C), nitrogen (N) isotope composition (15N) and nutrient (N, P, K, Ca, Mg, Mn, Fe, Cu and Zn) concentration of 11-year-old hoop pine (Araucaria cunninghamii Ait. (qld.gov.au)
  • physiological
  • However, this application requires better understanding of relationships between carbon isotope composition and plant physiological and morphological characteristics. (hindawi.com)
  • Therefore, altitudinal gradients provide unique experimental opportunities to study morphological and physiological responses of plants to environmental factors, as well as relationships between leaf carbon isotope composition and leaf morphological and physiological characteristics [ 9 - 14 ]. (hindawi.com)
  • grains
  • This study reports an evaluation of the technique, using two granite-arkose pairs (from Helmsdale, northern Scotland, and Shap, northwest England) where the composition of the detrital grains can be compared to feldspars in the granite from which they were derived. (geoscienceworld.org)
  • The results for the granite-arkose pairs show that the common Pb isotope signature of the detrital K-feldspar grains matches the in situ feldspars in the source granites. (geoscienceworld.org)
  • Measurements
  • From 1970 to the present day, projected trends agree with tropospheric measurements, suggesting that within analytical uncertainties, a constant average emission isotope delta (δ) is a compatible scenario. (atmos-chem-phys.net)
  • Efficiency
  • the rate of C accumulation for a given N content), water use efficiency (the ratio of whole-plant C gain to water loss), and stable isotope composition ( δ 13 C and δ 18 O) in seedlings of a diverse suite of species grown side-by-side in a tropical environment. (plantphysiol.org)
  • garnet
  • These values are consistent with the garnet being produced during incongruent melting of a metapelitic source that has a similar O-isotope composition to the Malmesbury Group. (geoscienceworld.org)
  • Quartz has a significantly lower closure temperature (~550 o C) than garnet, and sub-solidus oxygen isotope re-equilibration between quartz and feldspar during slow cooling ought to result in a greater variation in quartz δ 18 O values compared to that of garnet. (geoscienceworld.org)
  • soil
  • Environmental factors that change over time, such as moisture, can create dynamic changes in the isotopic composition of C assimilated by plants, and offers a unique opportunity to distinguish fast-responding plant C from slower-responding soil C pools, which under steady-state conditions may be too similar isotopically to partition. (epa.gov)
  • Monitoring the isotopic composition of soil respiration over a period of changing moisture conditions is potentially a useful approach for characterizing plant contributions to soil respiration. (epa.gov)
  • A third experiment, using closed-system soil incubations to avoid non-steady state mixing with atmospheric CO2, indicates that the isotopic composition of microbial soil respiration appears to be unchanging under a large range of soil moisture contents. (epa.gov)
  • Soil also reflected the isotopic composition of the vegetation but differed in its temporal integration. (secheresse.info)
  • changes
  • The oxygen and carbon isotope compositions of the sediment deposits in the various Central Asian basins have already been used to decipher both the topographic and climatic changes that occurred in that region during the Cenozoic, generally concentrating on one sedimentary section and/or on a limited time range and either using multiple-type samples including sandstone calcitic cements, marine carbonates, fossils, or paleosols. (mdpi.com)
  • The measurement uncertainty is too high to determine whether the average emission isotope δ has been affected by changes in CFC manufacturing processes or not. (atmos-chem-phys.net)
  • Carbon (δ13C) and nitrogen (δ15N) stable isotope compositions were used to elaborate the influences of changes in biotic and abiotic environmental parameters on the vegetation in the Mongolia-Manchurian grassland. (secheresse.info)
  • analysis
  • Results of X-Ray Diffraction (XRD) analysis, Triple Oxygen Isotope analysis and Scanning Electron Microscopic (SEM) studies are presented for stone fragments recovered from the North Central Province of Sri Lanka following a witnessed fireball event on 29 December 2012. (arxiv.org)
  • plant
  • The composition and cover of woody and understory species, along with the timing of stem growth, were characterized near minirhizotron installations at the south and north ends of the S1 bog in order to understand the relationship between root dynamics and the surrounding plant communities. (osti.gov)
  • We also took advantage of the contrasting physiology of the study species to test the theoretical basis for variation in the C and oxygen (O) stable isotope composition of plant dry matter. (plantphysiol.org)
  • results
  • The results of this test have informed a pilot study using the Pb isotope composition of detrital K-feldspar in Upper Carboniferous fluvial sedimentary rocks of northern England to constrain the sediment routing. (geoscienceworld.org)
  • Oxygen isotope results compare well with those of CI and CI-like chondrites but are inconsistent with the fulgurite hypothesis. (arxiv.org)