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  • mass spectrometry
  • When the carbon isotope signature of dried plant material is determined by mass spectrometry, a larger value for Δ implies that a higher p i / p a ratio prevailed at the time that carbon was being fixed, whereas smaller values imply that a lower p i / p a ratio must have prevailed. (webz.cz)
  • Analytical Validation of Accelerator Mass Spectrometry for Pharmaceutical Development: the Measurement of Carbon-14 Isotope Ratio. (unt.edu)
  • Accelerator mass spectrometry (AMS) is an isotope based measurement technology that utilizes carbon-14 labeled compounds in the pharmaceutical development process to measure compounds at very low concentrations, empowers microdosing as an investigational tool, and extends the utility of {sup 14}C labeled compounds to dramatically lower levels. (unt.edu)
  • fluxes
  • Based on the observed correlations between methane fluxes and delta 13C values of Chironomini and Daphnia in surface sediment samples, this suggests that more methane-derived carbon was available in warm periods compared with colder periods. (uu.nl)
  • organic carbon
  • A similar pattern in the concentration of chlorophyll a (Chl-a), particulate organic nitrogen (PON) and particulat (mas) e organic carbon (POC) was observed in both mesocosms. (worldwidescience.org)
  • A timescale for dissolved organic carbon production in equatorial {P}acific surface waters, Global Biogeochem. (clim-past.net)
  • Siderite associated with waning hydrothermal activity has low δ 13 C values (−11.1 to −5.8‰), suggesting the incorporation of oxidized, organic carbon from the footwall sequence and/or the addition of magmatic carbon. (geoscienceworld.org)
  • Existing atmospheric models underestimate concentrations of aerosol particulate matter and create gaps in our understanding of the atmospheric organic carbon budget, especially in relation to aqueous phase reactions that occur in fog and clouds. (epa.gov)
  • The outcomes of my research will provide clarification of the atmospheric organic carbon budget that could ideally be applied to total organic carbon and help ameliorate uncertainties in atmospheric models. (epa.gov)
  • heavier
  • The ratio of stable carbon isotopes in the fungi depends on that in their substrates but is shifted in favor of the heavier isotope. (deepdyve.com)
  • Photosynthesising leaves in effect discriminate against 13 CO 2 , so that 12 C is fixed more readily than its slightly heavier counterpart 13 C. The relative abundance of these two carbon isotopes in dried plant material can be measured by a ratio mass spectrometer with remarkable accuracy. (webz.cz)
  • Higher CO 2 partial pressure inside leaves permits greater discrimination, hence a numerically larger Δ, while lower CO 2 partial pressure inside leaves restricts dis-crimination against the heavier isotope, hence a numerically smaller Δ. (webz.cz)
  • soils
  • Large CO2 evasion to the atmosphere occurs as dissolved inorganic carbon (DIC) is transported from soils to streams. (diva-portal.org)
  • sediment
  • This first systematic evaluation of contemporary δ13Cdiatom controls demonstrates that diatoms have the potential to supply a record of carbon cycling through lake catchments from sediment records over millennial timescales. (nottingham.ac.uk)
  • The detailed record of Lake 227 nutrient concentration, phytoplankton assemblages, and trophic state changes allows for a detailed look at the standard interpretations of sediment core isotopes and the information that can be gained from their study. (uwaterloo.ca)
  • atmospheric
  • 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)
  • The primary motivation for this compilation is to provide the atmospheric boundary condition for historical simulations in the Coupled Model Intercomparison Project 6 (CMIP6) for models simulating carbon isotopes in the ocean or terrestrial biosphere. (geosci-model-dev.net)
  • We used stable carbon isotopes (δ 13 C) in tree rings to study the physiological responses of a tropical dry forest tree species in southern Mexico, Mimosa acantholoba to changes in atmospheric [CO 2 ] and variation in climate. (springer.com)
  • In this project, stable carbon isotopes will be used to track the progress of atmospheric aqueous phase reactions to determine if these processes affect particulate matter concentrations. (epa.gov)
  • Data
  • Carbon isotope ratio data in bone collagen from human skeletons found in Illinois, Ohio, and West Virginia, dated 4,000 B.C. to 1,500 A.D. The number and sex of the individuals found at each location are indicated in parentheses. (hhmi.org)
  • Hominins, sedges, and termites: New carbon isotope data from the Sterkfontein valley and Kruger National Park. (springer.com)
  • Ignat'ev, A. 2014-01-29 00:00:00 Data on the ratio of stable carbon isotopes in xylotrophic fungi and their xylic substrates are presented for the first time. (deepdyve.com)
  • The data may also be useful for other carbon cycle modelling activities. (geosci-model-dev.net)
  • The data suggest dissolved, biogenically produced carbon supplied proportionately to catchment productivity was critical in the rivers and soft water lakes. (nottingham.ac.uk)
  • The isotope and chronostratigraphical data together suggest that white laminae deposition is caused by extraordinary environmental events. (lancs.ac.uk)
  • The oxygen isotope data show that in the core of the feeder system (alteration zone I), the temperature and the δ 18 O H 2 O values were very high. (geoscienceworld.org)
  • measurement
  • Stable carbon isotope composition ( δ 13 C) provides an integrated measurement of internal plant physiological and external environmental properties influencing photosynthetic gas exchange over the time when the carbon was fixed [ 1 , 2 ]. (hindawi.com)
  • That measurement then provides a 'carbon isotope signature' for a given material, represented here by Δ. (webz.cz)
  • The isotope ratio measurement was specific (owing to the {sup 14}C label), stable across samples storage conditions for at least one year, linear over 4 orders of magnitude with an analytical range from one tenth Modern to at least 2000 Modern (instrument specific). (unt.edu)
  • Earth's
  • This post will offer a primer on some of the basics about what isotopes are, where they come from, and what isotopes can tell us about Earth's climate. (skepticalscience.com)
  • In turn, this implies that Earth's climate system and carbon cycle responded slowly to changes in incoming solar radiation. (clim-past.net)
  • demonstrates
  • It also demonstrates that carbon isotopes can expose structural weaknesses in the model and provide a key constraint that may guide future model development. (osti.gov)
  • freshwater
  • Improved understanding of environmental processes controlling carbon delivery and assimilation is essential to interpret changes in freshwater δ13Cdiatom. (nottingham.ac.uk)
  • methane
  • Using culturing experiments, it was demonstrated that methane-derived carbon is incorporated into chironomid head capsules. (uu.nl)
  • climate
  • Understanding the responses of tropical trees to increasing [CO 2 ] and climate change is important as tropical forests play an important role in carbon and hydrological cycles. (springer.com)
  • Thus, small changes in growth rates or water use efficiencies of tropical trees affect the carbon and water cycles, and the rate of climate change itself (Betts et al. (springer.com)