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1
Treydte, Kerstin, Jan Esper, and Holger Gärtner. "Stabile Isotope in der Dendroklimatologie | Stable isotopes and dendroclimatology." Schweizerische Zeitschrift fur Forstwesen 155, no. 6 (June 1, 2004): 222–32. http://dx.doi.org/10.3188/szf.2004.0222.
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This paper expounds the basics of isotope fixation in tree rings and relevant field and laboratory procedures. Examples from high mountain regions show both the potential and limits of employing these methods in dendroclimatological studies. Carbon isotopes yield seasonally resolved information on temperature,precipitation and relative humidity, whilst oxygen isotopes provide information on the isotope values of the source water,and thus, on precipitation. Inter-annual and decadal variations, in particular, reflect a strong common climatic signal that extends across a wide range of site ecologies. However, low frequency trends are masked by a non-climatic, human induced long-term trend, especially where carbon isotopes are concerned. At present,detrending methods are of a provisional nature and set a limit to stable isotopes for paleoclimatic questions. Highly resolved plant physiological and biochemical investigations should provide more insight into these unsolved problems.
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Sare, David T. J., John S. Millar, and Frederick J. Longstaffe. "Tracing dietary protein in red-backed voles (Clethrionomys gapperi) using stable isotopes of nitrogen and carbon." Canadian Journal of Zoology 83, no. 5 (May 1, 2005): 717–25. http://dx.doi.org/10.1139/z05-064.
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We examined the stable isotopes of nitrogen and carbon in a small mammal, the red-backed vole (Clethroinomys gapperi (Vigors, 1830)), to determine if isotope signatures reflect diet composition. Nitrogen- and carbon-isotope ratios in tissues from voles maintained on different protein levels in the laboratory were compared with wild-trapped voles. The isotopic fractionation of dietary nitrogen and carbon was also examined as food was digested in the stomach, incorporated into bone collagen, bioapatite, and hair, and excreted as feces. Nitrogen and carbon isotopes were fractionated differently depending on the isotopic composition and protein content of the diet. δ15N and δ13C values appear to be influenced by factors in addition to diet, such as macronutrients metabolized for respiration, metabolic rate, and periods of protein shortage.
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Swart, Peter K., and Jim J. Leder. "The utility of stable isotopic signatures in coral skeletons." Paleontological Society Papers 1 (October 1996): 249–91. http://dx.doi.org/10.1017/s1089332600000127.
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There is a fundamental ecologic differentiation between zooxanthellate and non-zooxanthellate corals. This paper reviews factors which govern the stable carbon and oxygen isotopic composition of these groups of corals. Although the stable carbon and oxygen isotope compositions of coral skeletons are strongly influenced by environmental and physiological factors, the precise mechanisms remain a matter of debate. In particular the oxygen isotopic composition is known to be governed by the temperature and the oxygen isotopic composition of the water and perhaps also by kinetic factors. In contrast the carbon isotopic composition is controlled by a combination of photosynthesis, respiration, autotrophy, heterotrophy, and the isotopic composition of dissolved inorganic carbon. Using a combination of carbon and oxygen isotopes it is possible to distinguish zooxanthellate from non-zooxanthellate corals.
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Krüger, J. P., J. Leifeld, and C. Alewell. "Degradation changes stable carbon isotope depth profiles in palsa peatlands." Biogeosciences 11, no. 12 (June 24, 2014): 3369–80. http://dx.doi.org/10.5194/bg-11-3369-2014.
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Abstract. Palsa peatlands are a significant carbon pool in the global carbon cycle and are projected to change by global warming due to accelerated permafrost thaw. Our aim was to use stable carbon isotopes as indicators of palsa degradation. Depth profiles of stable carbon isotopes generally reflect organic matter dynamics in soils with an increase of δ13C values during aerobic decomposition and stable or decreasing δ13C values with depth during anaerobic decomposition. Stable carbon isotope depth profiles of undisturbed and degraded sites of hummocks as well as hollows at three palsa peatlands in northern Sweden were used to investigate the degradation processes. The depth patterns of stable isotopes clearly differ between intact and degraded hummocks at all sites. Erosion and cryoturbation at the degraded sites significantly changes the stable carbon isotope depth profiles. At the intact hummocks the uplifting of peat material by permafrost is indicated by a turning in the δ13C depth trend, and this assessment is supported by a change in the C / N ratios. For hollows isotope patterns were less clear, but some hollows and degraded hollows in the palsa peatlands show differences in their stable carbon isotope depth profiles indicating enhanced degradation rates. We conclude that the degradation of palsa peatlands by accelerated permafrost thawing can be identified with stable carbon isotope depth profiles. At intact hummocks δ13C depth patterns display the uplifting of peat material by a change in peat decomposition processes.
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Krüger, J. P., J. Leifeld, and C. Alewell. "Degradation changes stable carbon isotope depth profiles in palsa peatlands." Biogeosciences Discussions 11, no. 1 (January 22, 2014): 1383–412. http://dx.doi.org/10.5194/bgd-11-1383-2014.
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Abstract. Palsa peatlands are a significant carbon pool in the global carbon cycle and are projected to change by global warming due to accelerated permafrost thaw. Our aim was to use stable carbon isotopes as indicators of palsa degradation. Depth profiles of stable carbon isotopes generally reflect organic matter dynamics in soils with an increase of δ13C values during aerobic decomposition and stable or decreasing δ13C values with depth during anaerobic decomposition. Stable carbon isotope depth profiles of undisturbed and degraded sites of hummocks as well as hollows at three palsa peatlands in northern Sweden were used to investigate the degradation processes. The depth patterns of stable isotopes clearly differ between intact and degraded hummocks at all sites. Erosion and cryoturbation at the degraded sites significantly changes the stable carbon isotope depth profiles. At the intact hummocks the uplifting of peat material by permafrost is indicated by a turning in the δ13C depth trend and this assessment is supported by a change in the C / N ratios. For hollows isotope patterns were less clear, but some hollows and degraded hollows in the palsa peatlands show differences in their stable carbon isotope depth profiles indicating enhanced degradation rates. We conclude that the degradation of palsa peatlands by accelerated permafrost thawing could be identified with stable carbon isotope depth profiles. At intact hummocks δ13C depth patterns display the uplifting of peat material by a change in peat decomposition processes.
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Kelly, Jeffrey F. "Stable isotopes of carbon and nitrogen in the study of avian and mammalian trophic ecology." Canadian Journal of Zoology 78, no. 1 (February 28, 2000): 1–27. http://dx.doi.org/10.1139/z99-165.
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Differential fractionation of stable isotopes of carbon during photosynthesis causes C4 plants and C3 plants to have distinct carbon-isotope signatures. In addition, marine C3 plants have stable-isotope ratios of carbon that are intermediate between C4 and terrestrial C3 plants. The direct incorporation of the carbon-isotope ratio (13C/12C) of plants into consumers' tissues makes this ratio useful in studies of animal ecology. The heavy isotope of nitrogen (15N) is preferentially incorporated into the tissues of the consumer from the diet, which results in a systematic enrichment in nitrogen-isotope ratio (15N/14N) with each trophic level. Consequently, stable isotopes of nitrogen have been used primarily to assess position in food chains. The literature pertaining to the use of stable isotopes of carbon and nitrogen in animal trophic ecology was reviewed. Data from 102 studies that reported stable-isotope ratios of carbon and (or) nitrogen of wild birds and (or) mammals were compiled and analyzed relative to diet, latitude, body size, and habitat moisture. These analyses supported the predicted relationships among trophic groups. Carbon-isotope ratios differed among species that relied on C3, C4, and marine food chains. Likewise, nitrogen-isotope ratios were enriched in terrestrial carnivorous mammals relative to terrestrial herbivorous mammals. Also, marine carnivores that ate vertebrates had nitrogen-isotope ratios that were enriched over the ratios of those that ate invertebrates. Data from the literature also indicated that (i) the carbon-isotope ratio of carnivore bone collagen was inversely related to latitude, which was likely the result of an inverse relationship between the proportion of carbon in the food chain that was fixed by C4 plants and latitude; (ii) seabirds and marine mammals from northern oceans had higher nitrogen-isotope ratios than those from southern oceans; (iii) the nitrogen-isotope ratios of terrestrial mammals that used xeric habitats were higher than the ratios of those that used mesic habitats, indicating that water stress can have important effects on the nitrogen-isotope ratio; (iv) there was no relationship between body mass and nitrogen-isotope ratio for either bone collagen or muscle of carnivores; and (v) there was linear covariation between stable-isotope ratios of carbon and nitrogen in marine food chains (but not in terrestrial C3 or C4 food chains), which is likely a product of increases in carbon-isotope ratio with trophic level in marine food chains. Differences in stable-isotope composition among trophic groups were detected despite variation attributable to geographic location, climate, and analytical techniques, indicating that these effects are large and pervasive. Consequently, as knowledge of the distribution of stable isotopes of carbon and nitrogen increases, they will probably become an increasingly important tool in the study of avian and mammalian trophic ecology.
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Benbow, Timothy J., Alan R. Hayman, Robert Van Hale, and Russell Frew. "Preparation of aqueous fatty acids for hydrogen and carbon stable isotope analysis by solid phase extraction." Marine and Freshwater Research 64, no. 4 (2013): 294. http://dx.doi.org/10.1071/mf12192.
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Stable isotope analyses of fatty acids in environmental waters provides important information as to their source(s). Analysis is often confounded due to low concentrations of fatty acids and/or a complex sample matrix requiring separation of the target analyte. The purpose of this study was to validate a method to extract fatty acids from natural waters using solid phase extraction (SPE) before compound specific isotope analysis (CSIA). Three SPE cartridges and multiple eluting solvents were tested to determine the efficiency, isotopic fractionation, and reproducibility of each extraction technique. Our results indicated that surface-modified styrene divinylbenzene cartridges, when eluted with methanol, caused negligible fractionation of the hydrogen isotopes and minimal fractionation of the carbon isotopes, but that isotopic fractionation occurred when compounds were only partially eluted from SPE cartridges. Compounds were also extracted from landfill leachate using both SPE and liquid–liquid extraction (LLE). The hydrogen isotope composition (δ2H) of compounds extracted from water using either method were within experimental precision and the carbon isotope composition (δ13C) of all but one fatty acid were within experimental precision. Therefore, these experiments prove the aforementioned SPE methods to be a convenient and precise method to extract fatty acids from natural waters before CSIA.
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Passey, Benjamin H. "Reconstructing Terrestrial Environments Using Stable Isotopes in Fossil Teeth and Paleosol Carbonates." Paleontological Society Papers 18 (November 2012): 167–94. http://dx.doi.org/10.1017/s1089332600002606.
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Carbon isotopes in Neogene-age fossil teeth and paleosol carbonates are commonly interpreted in the context of past distributions of C3 and C4 vegetation. These two plant types have very different distributions in relation to climate and ecology, and provide a robust basis for reconstructing terrestrial paleoclimates and paleoenvironments during the Neogene. Carbon isotopes in pre-Neogene fossil teeth are usually interpreted in the context of changes in the δ13C value of atmospheric CO2, and variable climate-dependent carbon-isotope discrimination in C3 plants. Carbon isotopes in pre-Neogene soil carbonates can be used to estimate past levels of atmospheric CO2. Oxygen isotopes in fossil teeth and paleosol carbonates primarily are influenced by the oxygen isotopic compositions of ancient rainfall and surface waters. The oxygen isotopic composition of rainfall is has a complex, but tractable, relationship with climate, and variably relates to temperature, elevation, precipitation amount, and other factors. Mammal species that rely on moisture in dietary plant tissues to satisfy their water requirements (rather than surface drinking water) may have oxygen isotopic compositions that track aridity. Thus, oxygen isotopes of fossil mammals can place broad constraints on paleoaridity. Carbonate clumped isotope thermometry allows for reconstruction of soil temperatures at the time of pedogenic carbonate mineralization. The method is unique because it is the only thermodynamically based isotopic paleothermometer that does not require assumptions about the isotopic composition of the fluid in which the archive mineral formed. Soil temperature reflects a complex interplay of air temperature, solar radiative heating, latent heat effects, soil thermal diffusivity, and seasonal variations of these parameters. Because plants and most animals live in and/or near the soil, soil temperature is an important aspect of terrestrial (paleo)climate.
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Jensen, Alexandria, William Ford, James Fox, and Admin Husic. "Improving In-Stream Nutrient Routines in Water Quality Models Using Stable Isotope Tracers: A Review and Synthesis." Transactions of the ASABE 61, no. 1 (2018): 139–57. http://dx.doi.org/10.13031/trans.12545.
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Abstract. Water quality models serve as an economically feasible alternative to quantify fluxes of nutrient pollution and to simulate effective mitigation strategies; however, their applicability is often questioned due to broad uncertainties in model structure and parameterization, leading to uncertain outputs. We argue that reduction of uncertainty is partially achieved by integrating stable isotope data streams within the water quality model architecture. This article outlines the use of stable isotopes as a response variable within water quality models to improve the model boundary conditions associated with nutrient source provenance, constrain model parameterization, and elucidate shortcomings in the model structure. To assist researchers in future modeling efforts, we provide an overview of stable isotope theory; review isotopic signatures and applications for relevant carbon, nitrogen, and phosphorus pools; identify biotic and abiotic processes that impact isotope transfer between pools; review existing models that have incorporated stable isotope signatures; and highlight recommendations based on synthesis of existing knowledge. Broadly, we find existing applications that use isotopes have high efficacy for reducing water quality model uncertainty. We make recommendations toward the future use of sediment stable isotope signatures, given their integrative capacity and practical analytical process. We also detail a method to incorporate stable isotopes into multi-objective modeling frameworks. Finally, we encourage watershed modelers to work closely with isotope geochemists to ensure proper integration of stable isotopes into in-stream nutrient fate and transport routines in water quality models. Keywords: Isotopes, Nutrients, Uncertainty analysis, Water quality modeling, Watershed.
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Roth, James D., and Keith A. Hobson. "Stable carbon and nitrogen isotopic fractionation between diet and tissue of captive red fox: implications for dietary reconstruction." Canadian Journal of Zoology 78, no. 5 (May 1, 2000): 848–52. http://dx.doi.org/10.1139/z00-008.
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The amount of isotopic fractionation (change in isotope ratios) between diet and animal tissues is generally poorly known and may be affected by trophic position. Diet-tissue fractionation of stable-carbon and -nitrogen isotopes was measured in several tissues of red foxes (Vulpes vulpes) raised on a commercial pellet feed. Stable carbon isotopic fractionation in red fox was positive for all tissues and was greatest in fur (2.6), intermediate in muscle (1.1), and least in liver and blood fractions (0.4-0.6). These carbon isotope fractionation values were greater than those previously measured for mammalian herbivores but were similar to values for marine mammals in most tissues. Little variation in stable nitrogen isotopic fractionation occurred among tissues, except in the blood fractions. Nitrogen isotopic fractionation was much higher in blood serum (4.2) than in liver, muscle, and fur (3.3-3.5). Cellular fractions of blood had the lowest fractionation values (2.6). There was a significant age effect in nitrogen- but not in carbon-isotopic fractionation. Subadult foxes (<1 year) were significantly enriched in 15N compared with adult foxes for fur, muscle, and liver (no blood was collected from adults). The cause of this enrichment is unclear, but it may be related to the higher rate of protein synthesis and catabolism in growing animals. This study is the first to report isotopic fractionation values for a terrestrial mammalian carnivore. Such estimates are necessary to interpret stable-isotope patterns in wild carnivores.
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DeSantis, L. R. G., and C. Hedberg. "Stable isotope ecology of the koala (Phascolarctos cinereus)." Australian Journal of Zoology 64, no. 5 (2016): 353. http://dx.doi.org/10.1071/zo16057.
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Australia has undergone significant climate change, both today and in the past. Koalas, due to their restricted diet of predominantly eucalyptus leaves and limited drinking behaviour may serve as model organisms for assessing past climate change via stable isotopes of tooth enamel. Here, we assess whether stable carbon and oxygen isotopes from tooth enamel record known climate variables, including proxies of relative aridity (e.g. mean annual precipitation, mean annual maximum temperature, and relative humidity). The results demonstrate significant negative relationships between oxygen isotope values and both relative humidity and mean annual precipitation, proxies for relative aridity. The best model for predicting enamel oxygen isotope values incorporates mean annual precipitation and modelled oxygen isotope values of local precipitation. These data and the absence of any relationship between modelled oxygen isotope precipitation values, independently, suggest that koalas do not track local precipitation values but instead record relative aridity. The lack of significant relationships between carbon isotopes and climate variables suggests that koalas may instead be tracking the density of forests and/or their location in the canopy. Collectively, these data suggest that koalas are model organisms for assessing relative aridity over time – much like kangaroos.
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Wang, Chong Jing, He Zhang, Jian Ming Chen, and Wen Bin Chen. "Organic Carbon & Nitrogen Stable Isotope Geochemistry of Anthraxolite from Different Fractures in Xiangxi, China." Applied Mechanics and Materials 733 (February 2015): 136–39. http://dx.doi.org/10.4028/www.scientific.net/amm.733.136.
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In order to analyze the stable organic carbon isotope characteristics and the causes of anthrax lite, 14 samples, containing hydrocarbon source rock, rock and anthrax lite, were selected to test the stable organic carbon and organic nitrogen isotope. Results showed that the relations of stable organic carbon isotope between source rock and anthrax lite were that δ13C source rock <δ13Csmall fault<δ13Clarge fault. Maybe the Early Cambrian anoxic events leaded the hydrocarbon source rock δ13C value low, and different metallogenic evolution and the isotopic fractionation process may be the cause of stable organic carbon isotope value differences between anthrax lite in large and small fault.
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McNicol, Gavin, Zhongjie Yu, Z. Carter Berry, Nathan Emery, Fiona M. Soper, and Wendy H. Yang. "Tracing plant–environment interactions from organismal to planetary scales using stable isotopes: a mini review." Emerging Topics in Life Sciences 5, no. 2 (February 26, 2021): 301–16. http://dx.doi.org/10.1042/etls20200277.
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Natural isotope variation forms a mosaic of isotopically distinct pools across the biosphere and flows between pools integrate plant ecology with global biogeochemical cycling. Carbon, nitrogen, and water isotopic ratios (among others) can be measured in plant tissues, at root and foliar interfaces, and in adjacent atmospheric, water, and soil environments. Natural abundance isotopes provide ecological insight to complement and enhance biogeochemical research, such as understanding the physiological conditions during photosynthetic assimilation (e.g. water stress) or the contribution of unusual plant water or nutrient sources (e.g. fog, foliar deposition). While foundational concepts and methods have endured through four decades of research, technological improvements that enable measurement at fine spatiotemporal scales, of multiple isotopes, and of isotopomers, are advancing the field of stable isotope ecology. For example, isotope studies now benefit from the maturation of field-portable infrared spectroscopy, which allows the exploration of plant–environment sensitivity at physiological timescales. Isotope ecology is also benefiting from, and contributing to, new understanding of the plant–soil–atmosphere system, such as improving the representation of soil carbon pools and turnover in land surface models. At larger Earth-system scales, a maturing global coverage of isotope data and new data from site networks offer exciting synthesis opportunities to merge the insights of single-or multi-isotope analysis with ecosystem and remote sensing data in a data-driven modeling framework, to create geospatial isotope products essential for studies of global environmental change.
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Ubelaker, Douglas H., and Douglas W. Owsley. "Isotopic Evidence for Diet in the Seventeenth-Century Colonial Chesapeake." American Antiquity 68, no. 1 (January 2003): 129–39. http://dx.doi.org/10.2307/3557036.
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Excavations of colonial period sites in Maryland and Virginia have produced human remains dating to the seventeenth century. In this study, we analyze stable isotopes of carbon and nitrogen from these remains to explore aspects of the diets of the individuals represented. Analyses of both stable carbon and nitrogen isotopes were conducted on preserved protein while stable carbon isotope analysis was also conducted on preserved biological apatite. Carbon isotope values (δ13N‰) ranged from -10.5 to -20.5 for collagen and -5.1 to -12.5 for bioapatite. Nitrogen isotope values (δ15N‰) ranged from 9.9 to 14.4. The data suggest dietary diversity among the individuals examined. Three factors contribute to this diversity: the availability of maize, variation in immigration histories of the individuals, and the differing lengths of time they spent in the American colonies.
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Arneson, Lynne S., Stephen MacAvoy, and Ethan Basset. "Metabolic protein replacement drives tissue turnover in adult mice." Canadian Journal of Zoology 84, no. 7 (July 1, 2006): 992–1002. http://dx.doi.org/10.1139/z06-081.
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Stable isotopes are increasingly being used to examine ecological and physiological questions, such as dietary choices, migration routes and timing, and physiological condition. To address these questions in the field, laboratory experiments must be done to determine diet–tissue discrimination values and turnover rates for stable isotopes in tissues. In this study, we examined the carbon and nitrogen turnover rates of whole blood, skeletal muscle, liver, kidney, heart, and brain, as well as the sulfur turnover rate of whole blood, skeletal muscle, and liver in Mus musculus L., 1758 following a diet change. By examining tissue isotope change in two groups of mice fed different diets, we found that tissues turnover at different rates (in order of fastest to slowest — liver, kidney, heart, brain, whole blood, skeletal muscle), but that carbon, nitrogen, and sulfur isotopes turned over with similar half-lives within a single tissue. By using a diet with different nutrient isotopic values, we also calculated that up to approximately 90%–95% of carbon in newly synthesized tissue was contributed by dietary protein. These results will provide field researchers with additional tissue isotopic half-lives to elucidate dietary history with a greater degree of certainty. The tissue sulfur half-lives provide an extra stable isotope that may be used in situations where carbon and nitrogen values do not differ between old and new nutrient sources.
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Fricke, Henry C., Raymond R. Rogers, and Terry A. Gates. "Hadrosaurid migration: inferences based on stable isotope comparisons among Late Cretaceous dinosaur localities." Paleobiology 35, no. 2 (2009): 270–88. http://dx.doi.org/10.1666/08025.1.
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Stable carbon and oxygen isotope ratios were measured for carbonate in samples of hadrosaurid tooth enamel and dentine, and gar scale ganoine and dentine from five geologically “contemporaneous“ (two-million-year resolution) and geographically distant late Campanian formations (Two Medicine, Dinosaur Park, Judith River, Kaiparowits, and Fruitland) in the Western Interior Basin. In all cases, isotopic offsets were observed between enamel and dentine from the same teeth, with dentine being characterized by higher and more variable carbon and oxygen isotope ratios. Isotopic offsets were also observed between gar ganoine and hadrosaur enamel in all sites analyzed. Both of these observations indicate that diagenetic overprinting of enamel isotope ratios did not entirely obfuscate primary signals. Decreases in carbon and oxygen isotope ratios were observed in hadrosaur enamel from east to west, and overlap in isotope ratios occurred only between two of the sampled sites (Dinosaur Park and Judith River Formations).The lack of isotopic overlap for enamel among localities could be due to diagenetic resetting of isotope ratios such that they reflect local groundwater effects rather than primary biogenic inputs. However, the large range in carbon isotope ratios, the consistent taxonomic offsets for enamel/ganoine data, and comparisons of enamel-dentine data from the same teeth all suggest that diagenesis is not the lone driver of the signal. In the absence of major alteration, the mostly likely explanation for the isotopic patterns observed is that hadrosaurids from the targeted formations were eating plants and drinking waters with distinct isotopic ratios. One implication of this reconstruction is that hadrosaurids in the Late Cretaceous of the Western Interior did not migrate to an extent that would obscure local isotopic signatures.
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Balcaen, A., E. Claeys, V. Fievez, P. Boeckx, O. van Cleemput, and S. de Smet. "Stable carbon isotope analysis of faecal and blood samples of sheep in relation to the diet." Proceedings of the British Society of Animal Science 2003 (2003): 159. http://dx.doi.org/10.1017/s1752756200013181.
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Stable isotopes have been extraordinarily helpful in understanding animal migration, diet, food webs and nutrient flow (Hilderbrand et al., 1996), based on the property that C3 and C4 plants possess distinctly different 13C/12C ratios (δ13C value) due to isotopic fractionation during photosynthetic carbon fixation (Smith & Epstein, 1971). Most woody species and temperate graminoids assimilate carbon via the Calvin cycle (C3), which discriminates stronger against the heavier isotope (13C) than Hatch-Slack (C4) species (tropical and subtropical graminoids and some shrubs). C3 and C4 plant species have mean δ13C values of -27 ‰ and -13 ‰ respectively (O’Leary, 1981). DeNiro & Epstein (1978) were one of the first to show that the isotopic composition of the whole animal body is similar to that of its diet. Other authors have also found relationships between the isotopic composition of animal tissues and the diet (González-Martin et al., 1999; Jones et al., 1979). The aim of this study was to investigate stable carbon isotope composition in sheep fed diets consisting of either C3 or C3+C4 plants.
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Montanari, Shaena. "Discrimination factors of carbon and nitrogen stable isotopes in meerkat feces." PeerJ 5 (June 13, 2017): e3436. http://dx.doi.org/10.7717/peerj.3436.
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Stable isotope analysis of feces can provide a non-invasive method for tracking the dietary habits of nearly any mammalian species. While fecal samples are often collected for macroscopic and genetic study, stable isotope analysis can also be applied to expand the knowledge of species-specific dietary ecology. It is somewhat unclear how digestion changes the isotope ratios of animals’ diets, so more controlled diet studies are needed. To date, most diet-to-feces controlled stable isotope experiments have been performed on herbivores, so in this study I analyzed the carbon and nitrogen stable isotope ratios in the diet and feces of the meerkat (Suricata suricatta), a small omnivorous mammal. The carbon trophic discrimination factor between diet and feces (Δ13Cfeces) is calculated to be 0.1 ± 1.5‰, which is not significantly different from zero, and in turn, not different than the dietary input. On the other hand, the nitrogen trophic discrimination factor (Δ15Nfeces) is 1.5 ± 1.1‰, which is significantly different from zero, meaning it is different than the average dietary input. Based on data generated in this experiment and a review of the published literature, carbon isotopes of feces characterize diet, while nitrogen isotope ratios of feces are consistently higher than dietary inputs, meaning a discrimination factor needs to be taken into account. The carbon and nitrogen stable isotope values of feces are an excellent snapshot of diet that can be used in concert with other analytical methods to better understand ecology, diets, and habitat use of mammals.
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Kristensen, D. K., E. Kristensen, M. C. Forchhammer, A. Michelsen, and N. M. Schmidt. "Arctic herbivore diet can be inferred from stable carbon and nitrogen isotopes in C3 plants, faeces, and wool." Canadian Journal of Zoology 89, no. 10 (October 2011): 892–99. http://dx.doi.org/10.1139/z11-073.
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The use of stable isotopes in diet analysis usually relies on the different photosynthetic pathways of C3 and C4 plants, and the resulting difference in carbon isotope signature. In the Arctic, however, plant species are exclusively C3, and carbon isotopes alone are therefore not suitable for studying arctic herbivore diets. In this study, we examined the potential of both stable carbon and nitrogen isotopes to reconstruct the diet of an arctic herbivore, here the muskox ( Ovibos moschatus (Zimmermann, 1780)), in northeast Greenland. The isotope composition of plant communities and functional plant groups was compared with those of muskox faeces and shed wool, as this is a noninvasive approach to obtain dietary information on different temporal scales. Plants with different root mycorrhizal status were found to have different δ15N values, whereas differences in δ13C, as expected, were less distinct. As a result, our examination mainly relied on stable nitrogen isotopes. The interpretation of stable isotopes from faeces was difficult because of the large uncertainty in diet–faeces fractionation, whereas isotope signatures from wool suggested that the muskox summer diet consists of around 80% graminoids and up to 20% willows. In conclusion, the diet composition of an arctic herbivore can indeed be inferred from stable isotopes in arctic areas, despite the lack of C4 plants.
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Londry, Kathleen L., and David J. Des Marais. "Stable Carbon Isotope Fractionation by Sulfate-Reducing Bacteria." Applied and Environmental Microbiology 69, no. 5 (May 2003): 2942–49. http://dx.doi.org/10.1128/aem.69.5.2942-2949.2003.
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ABSTRACT Biogeochemical transformations occurring in the anoxic zones of stratified sedimentary microbial communities can profoundly influence the isotopic and organic signatures preserved in the fossil record. Accordingly, we have determined carbon isotope discrimination that is associated with both heterotrophic and lithotrophic growth of pure cultures of sulfate-reducing bacteria (SRB). For heterotrophic-growth experiments, substrate consumption was monitored to completion. Sealed vessels containing SRB cultures were harvested at different time intervals, and δ13C values were determined for gaseous CO2, organic substrates, and products such as biomass. For three of the four SRB, carbon isotope effects between the substrates, acetate or lactate and CO2, and the cell biomass were small, ranging from 0 to 2‰. However, for Desulfotomaculum acetoxidans, the carbon incorporated into biomass was isotopically heavier than the available substrates by 8 to 9‰. SRB grown lithoautotrophically consumed less than 3% of the available CO2 and exhibited substantial discrimination (calculated as isotope fractionation factors [α]), as follows: for Desulfobacterium autotrophicum, α values ranged from 1.0100 to 1.0123; for Desulfobacter hydrogenophilus, the α value was 0.0138, and for Desulfotomaculum acetoxidans, the α value was 1.0310. Mixotrophic growth of Desulfovibrio desulfuricans on acetate and CO2 resulted in biomass with a δ13C composition intermediate to that of the substrates. The extent of fractionation depended on which enzymatic pathways were used, the direction in which the pathways operated, and the growth rate, but fractionation was not dependent on the growth phase. To the extent that environmental conditions affect the availability of organic substrates (e.g., acetate) and reducing power (e.g., H2), ecological forces can also influence carbon isotope discrimination by SRB.
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Pollard, A. M. "Isotopes and impact: a cautionary tale." Antiquity 85, no. 328 (May 2011): 631–38. http://dx.doi.org/10.1017/s0003598x00068034.
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There can be no doubt that isotopic studies have made a huge contribution to archaeology in recent years, so much so that isotope archaeology is now seen as an essential subdiscipline of archaeology in much the same way as isotope geochemistry is a key subdiscipline of geochemistry. Ignoring for current purposes the contribution made by the measurement of a particular radioactive isotope of carbon (14C) since 1950, we can date the beginnings of isotope archaeology to the mid 1960s with the first measurements of lead isotopes in archaeological metals and slags by Brill and Wampler (1965, 1967). This was followed by carbon stable isotopes in human bone collagen in the late 1970s, building on previous work measuring σ13C in archaeological bone for radiocarbon determinations (Vogel & Van der Merwe 1977; Van der Merwe & Vogel 1978). Other isotopes followed rapidly, such as nitrogen, oxygen, sulphur and hydrogen for archaeological, palaeoecological or palaeoclimatological purposes and, more recently, the heavier radiogenic isotopes of strontium and neodymium for determining the provenance of organic and inorganic materials (Pollard & Heron 2008).
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Gagnon, Chantal, and Keith A. Hobson. "Using stable isotopes to track frugivory in migratory passerines." Canadian Journal of Zoology 87, no. 11 (November 2009): 981–92. http://dx.doi.org/10.1139/z09-086.
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Several species of North American migratory songbirds undergo seasonal diet shifts from insects to fruits, but this phenomenon is poorly quantified. Measurement of naturally occurring stable isotopes of carbon (δ13C) and nitrogen (δ15N) are linked to sources of diets and trophic level, respectively. We used stable carbon (δ13C) and nitrogen (δ15N) isotope analyses of blood and claw tissues of 16 species of migratory songbirds to evaluate the timing and extent of frugivory over different periods. Species differed considerably in their tissue δ15N values, but we found poor isotopic segregation of species according to our a priori classifications as insectivores or omnivores. Season accounted for considerable variance in tissue δ15N values. However, only American Robin ( Turdus migratorius L., 1766), Northern Oriole ( Icterus galbula (L., 1758)), Gray Catbird ( Dumetella carolinensis (L., 1766)), Least Flycatcher ( Empidonax minimus (W.M. Baird and S.F. Baird, 1843)), and Warbling Vireo ( Vireo gilvus (Vieillot, 1808)) showed expected decrease in winter-grown tissue δ15N values compared with those grown in late summer. This indicates either that our a priori guild associations were incorrect and (or) that using stable isotopes to track frugivory at continental scales is problematic. We recommend that the isotope technique be used to track frugivory only in well-constrained systems where food-web δ15N follows reliable and understood trophic enrichment patterns.
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de Kluijver, A., P. L. Schoon, J. A. Downing, S. Schouten, and J. J. Middelburg. "Stable carbon isotope biogeochemistry of lakes along a trophic gradient." Biogeosciences 11, no. 22 (November 20, 2014): 6265–76. http://dx.doi.org/10.5194/bg-11-6265-2014.
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Abstract. The stable carbon (C) isotope variability of dissolved inorganic and organic C (DIC and DOC), particulate organic carbon (POC), glucose and polar-lipid derived fatty acids (PLFAs) was studied in a survey of 22 North American oligotrophic to eutrophic lakes. The δ13C of different PLFAs were used as proxy for phytoplankton producers and bacterial consumers. Lake pCO2 was primarily determined by autochthonous production (phytoplankton biomass), especially in eutrophic lakes, and governed the δ13C of DIC. All organic-carbon pools showed overall higher isotopic variability in eutrophic lakes (n = 11) compared to oligo-mesotrophic lakes (n = 11) because of the high variability in δ13C at the base of the food web (both autochthonous and allochthonous carbon). Phytoplankton δ13C was negatively related to lake pCO2 over all lakes and positively related to phytoplankton biomass in eutrophic lakes, which was also reflected in a large range in photosynthetic isotope fractionation (&varepsilon;CO2-phyto, 8–25‰). The carbon isotope ratio of allochthonous carbon in oligo-mesotrophic lakes was rather constant, while it varied in eutrophic lakes because of maize cultivation in the watershed.
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de Kluijver, A., P. L. Schoon, J. A. Downing, S. Schouten, and J. J. Middelburg. "Stable carbon isotope biogeochemistry of lakes along a trophic gradient." Biogeosciences Discussions 11, no. 5 (May 7, 2014): 6615–46. http://dx.doi.org/10.5194/bgd-11-6615-2014.
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Abstract. The stable carbon (C) isotope variability of dissolved inorganic and organic C (DIC and DOC), particulate organic carbon (POC), glucose and polar-lipid derived fatty acids (PLFA) were studied in a survey of 22 North American oligotrophic to eutrophic lakes. The δ13C of different PLFA were used as proxy for phytoplankton producers and bacterial consumers. Lake pCO2 was primarily determined by autochthonous production (phytoplankton biomass), especially in eutrophic lakes, and governed the δ13C of DIC. All organic-carbon pools showed larger isotopic variability in eutrophic lakes compared to oligo-mesotrophic lakes because of the high variability in δ13C at the base of the food web (both autochthonous and allochthonous carbon). Phytoplankton δ13C was negatively related to lake pCO2 over all lakes and positively related to phytoplankton biomass in eutrophic lakes, which was also reflected in a large range in photosynthetic isotope fractionation (&varepsilon;CO2-phyto, 8–25 ‰). The carbon isotope ratio of allochthonous carbon in oligo-mesotrophic lakes was rather constant, while it varied in eutrophic lakes because of maize cultivation in the watershed.
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Watson, Elizabeth Burke, Alejandro Hinojosa-Corona, Johannes R. Krause, Juan Carlos Herguera, Julianna McDonnell, Karen Raquel Villegas Villegas Manríquez, Michelle E. Gannon, and Andrew B. Gray. "Lagoon Biogeochemical Processing is Reflected in Spatial Patterns of Sediment Stable Isotopic Ratios." Journal of Marine Science and Engineering 8, no. 11 (November 3, 2020): 874. http://dx.doi.org/10.3390/jmse8110874.
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The spatial analysis of biota, particulate organic matter, and sediments for stable isotopes of carbon (δ13C), nitrogen (δ15N), and sulfur (δ34S) have proved useful for identifying patterns in productivity, nutrient pollution, and relationships between biological and physiochemical variables at the local and global scales. Yet such approaches are rarely applied to studies of lagoon or estuarine metabolism. Focusing on Bahía San Quintín, a heterotrophic seagrass-dominated lagoon on the Pacific coast of Baja California, México, we report on spatial patterns in surficial sediment CNS stable isotopic ratios as tracers of lagoon biogeochemical function. Stable nitrogen isotopes highlighted potential spatial variability in the balance between denitrification and nitrogen-fixation within the lagoon and identified an association between elevated δ15N levels and oyster culture, suggesting that oyster presence may be enhancing N2 production. Spatial patterns in δ34S covaried with sediment particle size, underlining the importance of sediment texture in determining the depth of sub-oxic-anoxic redox zones. Sediment carbon stable isotope ratios highlighted the lack of incorporation of seagrass carbon into seagrass meadow sediments, thus emphasizing the importance of phytoplankton or microphytobenthos for carbon accumulation in seagrass meadows. This report highlights the value of sediment isotopic values in corroborating spatial patterns in estuarine metabolism or macronutrient processing identified from chamber or flux-based studies. Stable isotope mapping can provide a useful addition to assessment of estuarine metabolism, or act as a stand-alone tool for generating hypotheses, identifying the influence of spatial gradients, and/or suggesting prime locations for investigation of microbial abundance or function.
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Feland, Brett C., and Sylvie A. Quideau. "Isotope applications to soil science at the University of Alberta — an historical perspective." Canadian Journal of Soil Science 100, no. 4 (December 1, 2020): 344–55. http://dx.doi.org/10.1139/cjss-2019-0153.
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For the past 70 yr, researchers in the Soil Science/Renewable Resources Department at the University of Alberta have used isotopes to study topics of ecological importance. This review highlights the soil isotope research conducted within our department over this time, including an historical overview of studies of interest. Analytical techniques and advances in instrumentation are discussed, focusing on the measurement of light stable isotope ratios (i.e., for C, H, N, S, and O) using isotope ratio mass spectrometry (IRMS). Early soil isotope work (1950–2000s) focused on agricultural soils and soil fertility issues. These studies included the use of radioactive isotopes such as 14C and 35S, and (or) artificially enriched stable isotopes including 15N-labelled fertilizers. More recently (2000–present), the scope of research widened to include natural-abundance stable isotope ratio studies as higher-sensitivity IRMS systems became more prevalent. Current isotope research topics include N biogeochemistry in natural and managed ecosystems, land management effects on greenhouse gas emissions, carbon cycling in northern landscapes, paleo-reconstruction in peatlands, carbon sequestration in boreal forests, and biodegradation of petroleum hydrocarbons. Further technological progress also enabled new techniques such as compound-specific IRMS analysis, including δ13C and δ2H measurements of soil n-alkanes and phospholipid fatty acids. In conclusion, current IRMS instrumentation presents unparalleled opportunities for multidisciplinary research to track carbon, plant nutrients, and pollutants as they move through soils.
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Kuznetsova, Anna Olegovna, Anna Andreevna Ivanova, Elena Adol'fovna Slagoda, and Yana Vital'evna Tikhonravova. "Stable isotopes of carbon in modern plants of tracts of the key terrain of Marre-Sale (Western Yamal)." Арктика и Антарктика, no. 1 (January 2020): 57–74. http://dx.doi.org/10.7256/2453-8922.2020.1.32204.
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Studies of the dependence of the accumulation of stable carbon isotopes on the growing conditions in modern plant species of tundra are very relevant. It was discovered that the same plant species accumulate the stable 13C isotope in different ways. The goal of this work is to reveal the relationship between the content of the stable 13C isotope in modern plants and the natural conditions of typical terrains of the tundra of the Western Yamal. At the geocryological station Marre-Sale, modern plant species were selected that grow under conditions of different moisture and remoteness from the sea. Modern plant species were determined using determinant atlases, carbon isotope contents using a DELTA V Advantage isotope mass spectrometer in the laboratory of LBIT (IMCES SB RAS). In different tracts, for identical plants the distribution of carbon isotopes depending on moisture was confirmed: the heavier 13С accumulates in dry ones, and lighter in humid and moist ones. It was determined that near the sea, the same plants of dry and wet tracts accumulate heavier 13С due to the influence of marine aerosols.
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McInerney, Francesca A., Caroline A. E. Strömberg, and James W. C. White. "The Neogene transition from C3 to C4 grasslands in North America: stable carbon isotope ratios of fossil phytoliths." Paleobiology 37, no. 1 (2011): 23–49. http://dx.doi.org/10.1666/09068.1.
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C4 grasses form the foundation of warm-climate grasslands and savannas and provide important food crops such as corn, but their Neogene rise to dominance is still not fully understood. Carbon isotope ratios of tooth enamel, soil carbonate, carbonate cements, and plant lipids indicate a late Miocene-Pliocene (8–2 Ma) transition from C3 vegetation to dominantly C4 grasses at many sites around the world. However, these isotopic proxies cannot identify whether the C4 grasses replaced woody vegetation (trees and shrubs) or C3 grasses. Here we propose a method for reconstructing the carbon isotope ratio of Neogene grasses using the carbon isotope ratio of organic matter trapped in plant silica bodies (phytoliths). Although a wide range of plants produce phytoliths, we hypothesize that in grass-dominated ecosystems the majority of phytoliths will be derived from grasses, and will yield a grass carbon isotope signature. Phytolith extracts can be contaminated by non-phytolith silica (e.g., volcanic ash). To test the feasibility of the method given these potential problems, we examined sample purity (phytolith versus non-phytolith silica), abundance of grass versus non-grass phytoliths, and carbon isotope ratios of phytolith extracts from late Miocene-Pliocene paleosols of the central Great Plains. Isotope results from the purest samples are compared with phytolith assemblage analysis of these same extracts. The dual record spans the interval of focus (ca. 12–2 Ma), allowing us, for the first time, to investigate how isotopic shifts correlate with floral change.We found that many samples contained high abundances of non-biogenic silica; therefore, only a small subset of “pure” samples (>50% of phytoliths by volume) with good preservation were considered to provide reliable carbon isotope ratios. All phytolith assemblages contained high proportions (on average 85%) of grass phytoliths, supporting our hypothesis for grass-dominated communities. Therefore, the carbon isotope ratio of pure, well-preserved samples that are dominated by grass biosilica is considered a reliable measure of the proportion of C3 and C4 grasses in the Neogene.The carbon isotope ratios of the pure fossil phytolith samples indicate a transition from predominantly C3 grasses to mixed C3-C4 grasses by 5.5 Ma and then a shift to more than 80% C4 grasses by 3–2 Ma. With the exception of the Pliocene sample, these isotopic data are broadly concordant with phytolith assemblages that show a general increase in C4 grasses in the late Miocene. However, phytolith assemblage analysis indicates lower relative abundance of C4 grasses in overall vegetation than do the carbon isotopes from the same phytolith assemblages. The discrepancy may relate to either (1) incomplete identification of (C4) PACMAD phytoliths, (2) higher production of non-diagnostic phytoliths in C4 grasses compared to C3 grasses, or (3) biases in the isotope record toward grasses rather than overall vegetation. The impact of potential incomplete characterization of (C4) PACMAD phytoliths on assemblage estimates of proportion of C4, though important, cannot reconcile discrepancies between the methods. We explore hypothesis (2) by analyzing a previously published data set of silica content in grasses and a small data set of modern grass leaf assemblage composition using analysis of variance, independent contrasts, and sign tests. These tests suggest that C4 grasses do not have more silica than C3 grasses; there is also no difference with regard to production of non-diagnostic phytoliths. Thus, it is most likely that the discrepancy between phytolith assemblages and isotope ratios is a consequence of hypothesis (3), that the isotope signature is influenced by the contribution of non-diagnostic grass phytoliths, whereas the assemblage composition is not. Assemblage-based estimates of % C4 within grasses, rather than overall vegetation, are in considerably better agreement with the isotope-based estimates. These results support the idea that, in grass-dominated assemblages, the phytolith carbon isotope method predominantly records shifts in dominant photosynthetic pathways among grasses, whereas phytolith assemblage analysis detects changes in overall vegetation. Carbon isotope ratios of fossil phytoliths in conjunction with phytolith assemblage analysis suggest that the late Neogene expansion of C4 grasses was largely at the expense of C3 grasses rather than C3 shrubs/trees. Stable isotopic analysis of phytoliths can therefore provide unique information about grass community changes during the Neogene, as well as help test how grass phytolith morphology relates to photosynthetic pathway.
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Gaigalas, Algirdas, and Stanislaw Halas. "Stable Isotopes (H, C, S) and the Origin of Baltic Amber." Geochronometria 33, no. -1 (January 1, 2009): 33–36. http://dx.doi.org/10.2478/v10003-009-0001-9.
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Stable Isotopes (H, C, S) and the Origin of Baltic Amber New results of isotope analysis of light elements (H, C and S) of a dozen Baltic amber samples are described and discussed. Carbon isotope composition was nearly constant (ca. -23‰), whereas sulphur and hydrogen varied in their isotope compositions from +4 to -28‰ and from -171 to -213‰, respectively. The formation and subsequent evolution of this material since its origin in Paleogene time until present is outlined.
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Smith, J. J., J. S. Millar, F. J. Longstaffe, and R. Boonstra. "The effect of metabolic rate on stable carbon and nitrogen isotope compositions in deer mice, Peromyscus maniculatus." Canadian Journal of Zoology 88, no. 1 (January 2010): 36–42. http://dx.doi.org/10.1139/z09-116.
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The stable isotopic compositions of nitrogen and carbon in animal tissues reflect diet. However, factors other than diet can also affect these stable isotope ratios, leading to misinterpretations of diet composition. To test the hypothesis that variation in metabolic rate alters the isotopic compositions of tissues, deer mice ( Peromyscus maniculatus (Wagner, 1845)) were kept at three temperatures (thermoneutral (23 °C), cool (5 °C), and cold (–10 °C)) and fed ad libitum. The changes in carbon and nitrogen isotope compositions of liver associated with the thermoneutral versus cool and cold conditions were very small in comparison with those arising from differences in diet. We conclude that temperature-induced variations in metabolic rate are insufficient to produce differences in the stable carbon or nitrogen isotope compositions that could be mistaken for changes in diet.
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Yurchenko, Anna, Andrey Voropaev, Elena Kozlova, Nikita Morozov, and Mikhail Spasennykh. "Application of the Data on δ13C and δ18O of Carbonates for the Study of Unconventional Reservoirs on the Example of the Bazhenov Source Rocks, Western Siberia, Russia." Geosciences 11, no. 7 (June 22, 2021): 264. http://dx.doi.org/10.3390/geosciences11070264.
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This paper addresses potential application of data on stable carbon and oxygen isotope composition of carbonates for study of organic rich source rocks on the example of the Late Jurassic–Early Cretaceous Bazhenov Formation (West Siberian petroleum basin, Russia). Geochemical studies were conducted for sections located in central (most productive) and peripheral (northern and southern) regions of the Bazhenov Formation distribution area, containing deposits formed under different conditions. We identified key factors impacting stable isotope composition of carbonate minerals and established relation of their isotope composition to the formation conditions. Using a thermodynamic model of carbon and oxygen isotope exchange in the carbonate–water–carbon dioxide system, it is shown that variations in the isotope composition of secondary carbonates are affected by isotopic composition of primary carbonates in sediments and by the isotope exchange reactions with water and carbon dioxide, generated during the source rocks transformation. Our results demonstrate that stable isotope data for carbonates in the Bazhenov Formation together with standard geochemical methods can be efficiently applied to determine sedimentation conditions and secondary alteration processes of oil source rocks.
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Alexander, Stuart A., Keith A. Hobson, Cheri L. Gratto-Trevor, and Antony W. Diamond. "Conventional and isotopic determinations of shorebird diets at an inland stopover: the importance of invertebrates and Potamogeton pectinatus tubers." Canadian Journal of Zoology 74, no. 6 (June 1, 1996): 1057–68. http://dx.doi.org/10.1139/z96-117.
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We used gut-content and stable-isotope techniques to determine diets of shorebirds staging at a prairie wetland complex. Stable-isotope ratios for carbon (13C/12C) and nitrogen (15N/14N) varied greatly within and among prey types and shorebirds, depending on location within the complex. Both dietary techniques suggested that Long-billed Dowitchers (Limnodromus scolopaceus) and Stilt Sandpipers (Calidris himantopus) ate mostly invertebrates, whereas Hudsonian (Limosa haemastica) and Marbled godwits (Limosa fedoa) ate mainly Potamogeton pectinatus tubers. In comparison, the stable-isotope technique indicated that godwits, especially juvenile Marbled Godwits, ate more invertebrates than is indicated by the gut-content analysis. The discrepancies between methods reflect the potential for bias in the application of these techniques. Researchers using stable isotopes to assess migratory shorebird diets should be aware of possible complications arising from isotopic variability within prey types, even over small geographic ranges. High isotopic variability at inland agro-wetland complexes might preclude reliable isotopic assessment of shorebird diets, especially long term. Rhizivory in godwits may be more common than is generally recognized, especially at inland stopovers during autumn migration in both North America and Eurasia, and should be factored into conservation initiatives for these species.
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Holzkämper, Steffen, Päivi Kaislahti Tillman, Peter Kuhry, and Jan Esper. "Comparison of stable carbon and oxygen isotopes in Picea glauca tree rings and Sphagnum fuscum moss remains from subarctic Canada." Quaternary Research 78, no. 2 (June 20, 2012): 295–302. http://dx.doi.org/10.1016/j.yqres.2012.05.014.
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AbstractStable isotope ratios from tree rings and peatland mosses have become important proxies of past climate variations. We here compare recent stable carbon and oxygen isotope ratios in cellulose of tree rings from white spruce (Picea glauca), growing near the arctic tree line; and cellulose of Sphagnum fuscum stems, growing in a hummock of a subarctic peatland, in west-central Canada. Results show that carbon isotopes in S. fuscum correlate significantly with July temperatures over the past ~20 yr. The oxygen isotopes correlate with both summer temperature and precipitation. Analyses of the tree-ring isotopes revealed summer temperatures to be the main controlling factor for carbon isotope variations, whereas tree-ring oxygen isotope ratios are controlled by a combination of spring temperatures and precipitation totals. We also explore the potential of combining high-frequency (annual) climate signals derived from long tree-ring series with low-frequency (decadal to centennial) climate signals derived from the moss remains in peat deposits. This cross-archive comparison revealed no association between the oxygen isotopes, which likely results from the varying sensitivity of the archives to different seasons. For the carbon isotopes, common variance could be achieved through adjustments of the Sphagnum age model within dating error.
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Louys, Julien, Peter Ditchfield, Carlo Meloro, Sarah Elton, and Laura C. Bishop. "Stable isotopes provide independent support for the use of mesowear variables for inferring diets in African antelopes." Proceedings of the Royal Society B: Biological Sciences 279, no. 1746 (August 29, 2012): 4441–46. http://dx.doi.org/10.1098/rspb.2012.1473.
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We examine the relationship between mesowear variables and carbon and nitrogen isotopes in 16 species of African antelope (Mammalia: Bovidae). We show significant differences in carbon and nitrogen isotope values between individuals exhibiting sharp versus round cusps, and high versus low occlusal relief. We show significant correlations between mesowear variables and both carbon and nitrogen isotopes. We find significant correlations between mesowear score and nitrogen, but not carbon isotopes. Finally, we find no significant correlations between hypsodonty index and either isotope examined. Our results provide strong support for the use of mesowear variables in palaeodietary reconstructions of antelopes. Our results further suggest that for the antelopes examined here, mesowear signals are a direct result of diet, while hyposodonty may be the result of phylogenetic legacy.
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Bahlmann, Enno, Frank Keppler, Julian Wittmer, Markus Greule, Heinz Friedrich Schöler, Richard Seifert, and Cornelius Zetzsch. "Evidence for a major missing source in the global chloromethane budget from stable carbon isotopes." Atmospheric Chemistry and Physics 19, no. 3 (February 8, 2019): 1703–19. http://dx.doi.org/10.5194/acp-19-1703-2019.
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Abstract. Chloromethane (CH3Cl) is the most important natural input of reactive chlorine to the stratosphere, contributing about 16 % to stratospheric ozone depletion. Due to the phase-out of anthropogenic emissions of chlorofluorocarbons, CH3Cl will largely control future levels of stratospheric chlorine. The tropical rainforest is commonly assumed to be the strongest single CH3Cl source, contributing over half of the global annual emissions of about 4000 to 5000 Gg (1 Gg = 109 g). This source shows a characteristic carbon isotope fingerprint, making isotopic investigations a promising tool for improving its atmospheric budget. Applying carbon isotopes to better constrain the atmospheric budget of CH3Cl requires sound information on the kinetic isotope effects for the main sink processes: the reaction with OH and Cl in the troposphere. We conducted photochemical CH3Cl degradation experiments in a 3500 dm3 smog chamber to determine the carbon isotope effect (ε=k13C/k12C-1) for the reaction of CH3Cl with OH and Cl. For the reaction of CH3Cl with OH, we determined an ε value of (-11.2±0.8) ‰ (n=3) and for the reaction with Cl we found an ε value of (-10.2±0.5) ‰ (n=1), which is 5 to 6 times smaller than previously reported. Our smaller isotope effects are strongly supported by the lack of any significant seasonal covariation in previously reported tropospheric δ13C(CH3Cl) values with the OH-driven seasonal cycle in tropospheric mixing ratios. Applying these new values for the carbon isotope effect to the global CH3Cl budget using a simple two hemispheric box model, we derive a tropical rainforest CH3Cl source of (670±200) Gg a−1, which is considerably smaller than previous estimates. A revision of previous bottom-up estimates, using above-ground biomass instead of rainforest area, strongly supports this lower estimate. Finally, our results suggest a large unknown CH3Cl source of (1530±200) Gg a−1.
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Brüggemann, N., A. Gessler, Z. Kayler, S. G. Keel, F. Badeck, M. Barthel, P. Boeckx, et al. "Carbon allocation and carbon isotope fluxes in the plant-soil-atmosphere continuum: a review." Biogeosciences 8, no. 11 (November 28, 2011): 3457–89. http://dx.doi.org/10.5194/bg-8-3457-2011.
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Abstract. The terrestrial carbon (C) cycle has received increasing interest over the past few decades, however, there is still a lack of understanding of the fate of newly assimilated C allocated within plants and to the soil, stored within ecosystems and lost to the atmosphere. Stable carbon isotope studies can give novel insights into these issues. In this review we provide an overview of an emerging picture of plant-soil-atmosphere C fluxes, as based on C isotope studies, and identify processes determining related C isotope signatures. The first part of the review focuses on isotopic fractionation processes within plants during and after photosynthesis. The second major part elaborates on plant-internal and plant-rhizosphere C allocation patterns at different time scales (diel, seasonal, interannual), including the speed of C transfer and time lags in the coupling of assimilation and respiration, as well as the magnitude and controls of plant-soil C allocation and respiratory fluxes. Plant responses to changing environmental conditions, the functional relationship between the physiological and phenological status of plants and C transfer, and interactions between C, water and nutrient dynamics are discussed. The role of the C counterflow from the rhizosphere to the aboveground parts of the plants, e.g. via CO2 dissolved in the xylem water or as xylem-transported sugars, is highlighted. The third part is centered around belowground C turnover, focusing especially on above- and belowground litter inputs, soil organic matter formation and turnover, production and loss of dissolved organic C, soil respiration and CO2 fixation by soil microbes. Furthermore, plant controls on microbial communities and activity via exudates and litter production as well as microbial community effects on C mineralization are reviewed. A further part of the paper is dedicated to physical interactions between soil CO2 and the soil matrix, such as CO2 diffusion and dissolution processes within the soil profile. Finally, we highlight state-of-the-art stable isotope methodologies and their latest developments. From the presented evidence we conclude that there exists a tight coupling of physical, chemical and biological processes involved in C cycling and C isotope fluxes in the plant-soil-atmosphere system. Generally, research using information from C isotopes allows an integrated view of the different processes involved. However, complex interactions among the range of processes complicate or currently impede the interpretation of isotopic signals in CO2 or organic compounds at the plant and ecosystem level. This review tries to identify present knowledge gaps in correctly interpreting carbon stable isotope signals in the plant-soil-atmosphere system and how future research approaches could contribute to closing these gaps.
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Ruiz-Cooley, R. I., Unai Markaida, D. Gendron, and S. Aguíñiga. "Stable isotopes in jumbo squid (Dosidicus gigas) beaks to estimate its trophic position: comparison between stomach contents and stable isotopes." Journal of the Marine Biological Association of the United Kingdom 86, no. 2 (March 13, 2006): 437–45. http://dx.doi.org/10.1017/s0025315406013324.
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Stomach contents and carbon (C) and nitrogen (N) stable isotope analysis were used to evaluate trophic relationships of jumbo squid, Dosidicus gigas. Buccal masses, beaks and stomach contents of large and medium maturing-sized jumbo squid and muscle from its main prey, the myctophid Benthosema panamense, were collected in the Gulf of California, Mexico during 1996, 1997 and 1999. Both the quantified C and N-isotope ratios in muscle, and stomach content analysis revealed that larger-sized maturing squid showed a higher trophic position than medium-sized individuals. However, a discrepancy between stomach contents versus stable isotope analyses was found in evaluating trophic relationships. Simple dilution models as a function of growth were used to estimate the C and N renewal dietary shift for jumbo squid. Estimates of the initial C and N pools in D. gigas with an initial age of 70 days and 210 days indicated isotopic shifts of 32% after a threefold biomass increase and 25% after a fourfold biomass increase, respectively. Additionally, beak samples of jumbo squid were evaluated as an alternative tissue to estimate squid trophic position using stable isotopes. The results showed a significant correlation between stable isotope ratios from muscle and beak samples. Muscle isotope values were higher than beak by 1% and 4% for δ13C and δ15N respectively. A test with jumbo squid beaks collected from a stomach of a stranded sperm whale confirmed the viability of this method.
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Watkinson, Charles J., Peter Gasson, Gareth O. Rees, and Markus Boner. "The Development and Use of Isoscapes to Determine the Geographical Origin of Quercus spp. in the United States." Forests 11, no. 8 (August 7, 2020): 862. http://dx.doi.org/10.3390/f11080862.
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The stable isotope ratios of oxygen, hydrogen, carbon and sulfur from extracted wood of 87 samples of oaks from the United States were analysed. Relationships with climate variables and the stable isotope ratios of the 69 training dataset samples were investigated to a monthly resolution using long-term monthly mean climate data from NASA and the University of East Anglia’s Climate Research Unit, in conjunction with forecast data for hydrogen and oxygen isotope ratios in precipitation. These relationships were used to construct model isoscapes for oxygen, hydrogen, carbon and sulfur for US oak with the aim of using them to forecast isotopic patterns in areas that were not sampled and predict values in samples not used to construct the models. The leading predictors for isoscape generation were oxygen isotope ratios in January precipitation for oak oxygen isotope ratios, hydrogen isotope ratios in July precipitation for oak hydrogen isotope ratios, water vapour in April for carbon isotope ratios, and reflected shortwave radiation in March in combination with sulfate concentration in May for oak sulfur isotopes. The generated isoscapes can be used to show regions an unknown sample may have originated from with a resolution dependent on the rarity of the stable isotope signature within the United States. The models were assessed using the data of 18 samples of georeferenced oak. The assessment found that 100% of oxygen, 94% of hydrogen, 78% of carbon, and 94% of sulfur isotope ratios in the 18 test dataset samples fell within two standard deviations of the isoscape models. Using the results of the isoscapes in combination found that there were 4/18 test samples which did not fall within two standard deviations of the four models, this is largely attributed to the lower predictive power of the carbon isoscape model in conjunction with high local variability in carbon isotope ratios in both the test and training data. The method by which this geographic origin method has been developed will be useful to combat illegal logging and to validate legal supply chains for the purpose of good practice due diligence.
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Marentes, E., R. A. Vanderpool, and B. J. Shelp. "Boron-isotope fractionation in plants." Canadian Journal of Plant Science 77, no. 4 (October 1, 1997): 627–29. http://dx.doi.org/10.4141/p97-010.
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Naturally-occurring variations in the abundance of stable isotopes of carbon, nitrogen, oxygen, and other elements in plants have been reported and are now used to understand various physiological processes in plants. Boron (B) isotopic variation in several plant species has been documented, but no determination as to whether plants fractionate the stable isotopes of boron, 11B and 10B, has been made. Here, we report that plants with differing B requirements (wheat, corn and broccoli) fractionated boron. The whole plant was enriched in 11B relative to the nutrient solution, and the leaves were enriched in 10B and the stem in 11B relative to the xylem sap. Although at present, a mechanistic role for boron in plants is uncertain, potential fractionating mechanisms are discussed. Key words: Brassica oleracea var. italica Plenck (broccoli), Triticum aestivum L. (wheat), Zea mays L. (corn), boron, isotope fractionation
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Federer, R. N., T. E. Hollmén, D. Esler, M. J. Wooller, and S. W. Wang. "Stable carbon and nitrogen isotope discrimination factors from diet to blood plasma, cellular blood, feathers, and adipose tissue fatty acids in Spectacled Eiders (Somateria fischeri)." Canadian Journal of Zoology 88, no. 9 (September 2010): 866–74. http://dx.doi.org/10.1139/z10-052.
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Stable isotope analyses of animal tissues can be used to infer diet through application of mixing models. An important component in a mixing model is the incorporation of stable isotope discrimination factors so that isotopic shifts between diet and tissues built from the diet can be accounted for when comparing tissues to potential food sources. We determined the stable carbon and nitrogen isotopic discrimination factors between lipid-free diet and blood plasma, cellular blood, and adult chest contour feathers for captive female Spectacled Eiders ( Somateria fischeri (Brandt, 1847)). Mean discrimination factors for blood components and feathers were either similar or slightly larger compared with previously studied species. Additionally, we determined the stable carbon isotope discrimination factors between dietary lipids and adipose tissue fatty acids using three adipose tissue biopsies from captive male Spectacled Eiders that were fed three different diet treatments. Isotopic signatures of adipose tissue fatty acids closely reflected shifts in the diet and were either similar to or increased relative to diet. Our study provides a foundation for research using tissues as end-members in stable isotope nutrient allocation models and foraging ecology studies of Spectacled Eiders, and will provide the most applicable isotope data to date for sea ducks.
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Middelburg, J. J. "Stable isotopes dissect food webs from top to the bottom." Biogeosciences Discussions 10, no. 9 (September 10, 2013): 14923–52. http://dx.doi.org/10.5194/bgd-10-14923-2013.
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Abstract. Stable isotopes have been used extensively to study food web functioning, i.e. the flow of energy and matter among organisms. Traditional food-web studies are based on the natural variability of carbon and nitrogen isotopes and are limited to larger organisms that can be physically separated from their environment. Recent developments allow isotope ratio measurements of microbes and this in turn allows then measurement of entire food webs, i.e. from small producers at the bottom to large consumers at the top. Here, I provide a concise review on the use and potential of stable isotope to reconstruct end-to-end food webs. I will first discuss food web reconstruction based on natural abundances isotope data and will then show that the use of stable isotopes as deliberately added tracers provides complementary information. Finally, challenges and opportunities for end-to-end food web reconstructions in a changing world are discussed.
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Kline, Jr., Thomas C., William J. Wilson, and John J. Goering. "Natural isotope indicators of fish migration at Prudhoe Bay, Alaska." Canadian Journal of Fisheries and Aquatic Sciences 55, no. 6 (June 1, 1998): 1494–502. http://dx.doi.org/10.1139/f98-012.
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A dichotomy in the natural stable carbon isotope abundance measured in tissues of obligate freshwater and marine fishes from the Alaskan Arctic coastal plain suggested that the methodology can be used to differentiate recent freshwater from marine feeding in migratory fishes. Natural stable carbon isotope ratio of migratory fishes reflected differences of feeding habitat in relation to known life-history patterns. Use of the stable isotope methodology as a tool for proxy analysis of fish behavior in present and future Arctic environmental monitoring studies is suggested from analysis of age-specific isotopic ratio differences in broad whitefish (Coregonus nasus) and Arctic cisco (Coregonus autumnalis).
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Hungate, Bruce A., Rebecca L. Mau, Egbert Schwartz, J. Gregory Caporaso, Paul Dijkstra, Natasja van Gestel, Benjamin J. Koch, et al. "Quantitative Microbial Ecology through Stable Isotope Probing." Applied and Environmental Microbiology 81, no. 21 (August 21, 2015): 7570–81. http://dx.doi.org/10.1128/aem.02280-15.
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ABSTRACTBacteria grow and transform elements at different rates, and as yet, quantifying this variation in the environment is difficult. Determining isotope enrichment with fine taxonomic resolution after exposure to isotope tracers could help, but there are few suitable techniques. We propose a modification tostableisotopeprobing (SIP) that enables the isotopic composition of DNA from individual bacterial taxa after exposure to isotope tracers to be determined. In our modification, after isopycnic centrifugation, DNA is collected in multiple density fractions, and each fraction is sequenced separately. Taxon-specific density curves are produced for labeled and nonlabeled treatments, from which the shift in density for each individual taxon in response to isotope labeling is calculated. Expressing each taxon's density shift relative to that taxon's density measured without isotope enrichment accounts for the influence of nucleic acid composition on density and isolates the influence of isotope tracer assimilation. The shift in density translates quantitatively to isotopic enrichment. Because this revision to SIP allows quantitative measurements of isotope enrichment, we propose to call it quantitative stable isotope probing (qSIP). We demonstrated qSIP using soil incubations, in which soil bacteria exhibited strong taxonomic variations in18O and13C composition after exposure to [18O]water or [13C]glucose. The addition of glucose increased the assimilation of18O into DNA from [18O]water. However, the increase in18O assimilation was greater than expected based on utilization of glucose-derived carbon alone, because the addition of glucose indirectly stimulated bacteria to utilize other substrates for growth. This example illustrates the benefit of a quantitative approach to stable isotope probing.
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Nardoto, Gabriela Bielefeld, Patricia Barboza de Godoy, Epaminondas Sansigolo de Barros Ferraz, Jean Pierre Henry Balbaud Ometto, and Luiz Antonio Martinelli. "Stable carbon and nitrogen isotopic fractionation between diet and swine tissues." Scientia Agricola 63, no. 6 (December 2006): 579–82. http://dx.doi.org/10.1590/s0103-90162006000600012.
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Naturally occurring stable isotope ratios can be a powerful tool in studies of animal nutrition, provided that the assumptions required for dietary reconstruction are validated by studies such as the one presented here. The objective of this study was to document the magnitude of isotopic fractionation between swine diet and their different tissues. For this, the isotopic ratios of carbon and nitrogen of the diet and selected tissues (hair, nail, liver, muscle, fat and cartilage) were determined. The delta13C and delta15N of the diet were -15.9‰ and 1.3‰, respectively, and all delta15N of swine tissues were 2.2 to 3.0‰ enriched in 15N in relation to the diet. Little variation in delta15N occurred among tissues, with exception to liver that was less enriched in 15N than the nail. Nail and hair presented no 13C enrichment relative to diet. Cartilage was ~1.0‰ enriched in 13C as compared to diet. Liver and muscle were on average 2.1‰ more depleted in 13C in relation to diet as well as fat tissues. Some of the C and N isotope ratios of swine tissues differed in organs, but the isotopic fractionation trends among tissues appears to be similar to other mammals. Therefore our data provide a good baseline to interpret stable isotope patterns in domestic mammals (such as swine) in controlled or semi-controlled experiments.
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Mendes, Sónia, Jason Newton, Robert J. Reid, Alexandros Frantzis, and Graham J. Pierce. "Stable isotope profiles in sperm whale teeth: variations between areas and sexes." Journal of the Marine Biological Association of the United Kingdom 87, no. 2 (April 2007): 621–27. http://dx.doi.org/10.1017/s0025315407056019.
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Sperm whale (Physeter macrocephalus) teeth were used to investigate whether variation in the chronological profiles of carbon and nitrogen stable isotope ratios along dentine growth layers could reflect differences in ontogenetic movements and/or dietary shifts in animals from different regions and sexes, as well as to show the differences in the isotopic environments experienced by these animals. Absolute isotopic ratios ranged from -14.1 to -11.0‰ for carbon and 10.8 to 18.1‰ for nitrogen, with the whale from the Indian Ocean, the two from the Mediterranean Sea and the female from the Azores presenting the most different median isotopic ratios. The Icelandic and the Indian Ocean males showed the expected decrease in δ13C around the age of ten, denoting male segregation from natal groups. For the latter, this was larger by almost twofold compared to other teeth, probably due to the much stronger latitudinal gradient in planktonic δ13C in the southern hemisphere. The Mediterranean Sea whales exhibited the lowest median δ15N values, probably reflecting the oligotrophy of this sea, while the male showed a marked change in isotopes around the age of 20 that could indicate a move to the eastern basin or a temporal change in basal isotopic signatures. The Atlantic females did not show a marked change in δ13C as expected since they stay in low latitudes throughout their lives. Stable isotope profiles in whale teeth can be used to investigate differences in the timings of ontogenetic movements and dietary history between individuals and sexes, and the biogeochemistry of different regions inhabited, and have the potential to allow inferences to be made about population substructure.
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West, Jason B., Janet M. Hurley, and James R. Ehleringer. "Stable Isotope Ratios of Marijuana. I. Carbon and Nitrogen Stable Isotopes Describe Growth Conditions*." Journal of Forensic Sciences 54, no. 1 (January 2009): 84–89. http://dx.doi.org/10.1111/j.1556-4029.2008.00909.x.
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Uriarte, Amaya, Alberto García, Aurelio Ortega, Fernando De la Gándara, José Quintanilla, and Raúl Laiz-Carrión. "Isotopic discrimination factors and nitrogen turnover rates in reared Atlantic bluefin tuna larvae (Thunnus thynnus): effects of maternal transmission." Scientia Marina 80, no. 4 (November 22, 2016): 447. http://dx.doi.org/10.3989/scimar.04435.25a.
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The use of stable isotope analysis to study animal diets requires estimates of isotopic turnover rates (half time, t50) and discrimination factors (Δ) for an accurate interpretation of trophic patterns. The stable isotopes of carbon and nitrogen were analysed for eggs and reared larvae of Thunnus thynnus, as well as for the different diets supplied during the experiment. The results showed high values of δ15N in eggs and larvae (n=646) until 4 DAH. After this time lapse, the stable isotope values declined progressively until 12 DAH, when notochord flexion began. The δ13C showed an inverse trend, suggesting that maternal inheritance of the stable isotopes is evident until pre-flexion stages. This study proposes a model for estimating maternal isotopic signatures of bluefin broodstock. After notochord flexion, larvae were fed with aquaculture-bred gilthead seabream, which resulted in a rapid increase of bluefin larvae δ15N values together with a rapid decrease in δ13C values. The estimated nitrogen half-time to reach the steady state from the diet was 2.5±0.3 days and the discrimination factor was 0.4±0.3(‰). These results represent the first data set that has allowed isotopic nitrogen turnover rates and discrimination factors of the larval stages of bluefin tuna to be estimated.
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Gennett, Judith A., and Ethan L. Grossman. "Oxygen and Carbon Isotope Trends in a Late Glacial-Holocene Pollen Site in Wyoming, U.S.A." Géographie physique et Quaternaire 40, no. 2 (December 4, 2007): 161–69. http://dx.doi.org/10.7202/032636ar.
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ABSTRACT Stable isotope studies of North American Late Glacial and Holocene lake sediments are few. Previous studies of pollen sites in Indiana, South Dakota, and the Great Lakes area show low δ18O values during deglaciation, rising to a Hypsithermal peak, and provide paleoenvironmental reconstructions similar to those obtained from pollen studies. Blacktail Pond, located in Douglas fir steppe in northern Yellowstone National Park, Wyoming, is one of the highest elevation lakes (2018 m) yet studied with both pollen and stable isotopes. Analyses of marls yield low oxygen and carbon isotope values at the base of the core probably due to meltwater influx at 12,500 to 14,000 BP. Tundra vegetation persisted for about an additional 1,500 years following the end of meltwater input. Later, more enriched isotope values fluctuate due to the high sensitivity of Blacktail Pond to evaporation and CO2 exchange because of its shallow depth. These processes result in a covariance between δ13C and δ18O related to the residence time of water in the pond; they exert a primary control on the isotopic composition of the Holocene marl. It may be possible to filter the data for residence time effects and extract additional paleoenvironmental information based on the offsets of isotopic data from the δ13C-δ18O trend for a particular pollen zone.
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Zuiderweg, A., J. Kaiser, J. C. Laube, T. Röckmann, and R. Holzinger. "Stable carbon isotope fractionation in the UV photolysis of CFC-11 and CFC-12." Atmospheric Chemistry and Physics Discussions 11, no. 12 (December 16, 2011): 33173–89. http://dx.doi.org/10.5194/acpd-11-33173-2011.
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Abstract. The chlorofluorocarbons CFC-11 (CCl3F) and CFC-12 (CCl2F2) are stable atmospheric compounds that are produced at the earth's surface, but removed only at high altitudes in the stratosphere, where their removal liberates atomic chlorine that then catalytically destroys stratospheric ozone. For such long-lived compounds, isotope effects in the stratospheric removal reactions have a large effect on their global isotope budgets. We have determined the photolytic isotope fractionation for stable carbon isotopes of CFC-11 and CFC-12 in laboratory experiments. 13C/12C isotope fractionations (&varepsilon;) range from (−23.7 ± 0.9) to (−17.5 ± 0.4)‰ for CFC-11 and (−69.2 ± 3.4) to (−49.4 ± 2.3)‰ for CFC-12 between 203 and 288 K, a temperature range relevant to conditions in the troposphere and stratosphere. These results suggest that CFCs should become strongly enriched in 13C with decreasing mixing ratio in the stratosphere, similar to what has been recently observed for CFC chlorine isotopes. In conjunction with the strong variations in CFC emissions before and after the Montréal Protocol, the stratospheric enrichments should also lead to a significant temporal increase in the 13C content of the CFCs at the surface over the past decades, which should be recorded in atmospheric air archives such as firn air.
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Zuiderweg, A., J. Kaiser, J. C. Laube, T. Röckmann, and R. Holzinger. "Stable carbon isotope fractionation in the UV photolysis of CFC-11 and CFC-12." Atmospheric Chemistry and Physics 12, no. 10 (May 16, 2012): 4379–85. http://dx.doi.org/10.5194/acp-12-4379-2012.
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Abstract. The chlorofluorocarbons CFC-11 (CFCl3) and CFC-12 (CF2Cl2) are stable atmospheric compounds that are produced at the earth's surface, but removed only at high altitudes in the stratosphere by photolytic reactions. Their removal liberates atomic chlorine that then catalytically destroys stratospheric ozone. For such long-lived compounds, isotope effects in the stratospheric removal reactions have a large effect on their global isotope budgets. We have demonstrated a photolytic isotope fractionation for stable carbon isotopes of CFC-11 and CFC-12 in laboratory experiments using broadband UV-C (190–230 nm) light. 13C/12C isotope fractionations (ε) range from (−23.8±0.9) to (−17.7±0.4) ‰ for CFC-11 and (−66.2±3.1) to (−51.0±2.9) ‰ for CFC-12 between 203 and 288 K, a temperature range relevant to conditions in the troposphere and stratosphere. These results suggest that CFCs should become strongly enriched in 13C with decreasing mixing ratio in the stratosphere, similar to what has been recently observed for CFC chlorine isotopes. In conjunction with the strong variations in CFC emissions before and after the Montréal Protocol, the stratospheric enrichments should also lead to a significant temporal increase in the 13C content of the CFCs at the surface over the past decades, which should be recorded in atmospheric air archives such as firn air.