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Sample records for 18o stable isotope

  1. Stable isotope ( 18O) investigations on the processes controlling fluoride contamination of groundwater

    NASA Astrophysics Data System (ADS)

    Datta, P. S.; Deb, D. L.; Tyagi, S. K.

    1996-10-01

    Groundwater is being used extensively in the Delhi area for both irrigation and raw water requirement. Fluoride contamination in groundwater is therefore a matter of concern for the planners and managers of water resources. Stable isotope ( 18O) and fluoride signatures in groundwater have been discussed, in this context, to characterise the sources and controlling processes of fluoride contamination. The study indicates that almost 50% of the area is affected by fluoride contamination beyond the maximum permissible limit. The wide range (0.10-16.5 ppm) in fluoride concentration suggests contributions from both point and non-point sources. Very high fluoride levels in groundwater are mostly found in the vicinity of brick kilns. Significant quantities of evaporated (isotopically enriched) rainfall, irrigation water and surface runoff water from surrounding farmland also percolate along with fluoride salts from the soils to the groundwater system. The process of adsorption and dispersion of fluoride species in the soil as well as lateral mixing of groundwater along specific flow-paths control the groundwater fluoride and 18O composition. The groundwater system has more than two isotopically distinct non-point source origins, causing spatial and temporal variations in fluoride concentration. Issues related to harmful effects of excessive use of high-fluoride groundwater and management options have also been discussed.

  2. Stable oxygen isotopes (delta18(O)) in Austrocedrus chilensis tree rings reflect climate variability in northwestern Patagonia, Argentina.

    PubMed

    Roig, F A; Siegwolf, R; Boninsegna, J A

    2006-11-01

    The stable oxygen isotope (delta (18)O) composition of Austrocedrus chilensis (D. Don) Endl. (Cupressaceae) tree rings potentially provide retrospective views of changes in environment and climate in the semi-arid lands of Patagonia. We report the development of the first annually resolved delta (18)O tree-ring chronology obtained from natural forests of the foothills of the northwestern Patagonian Andes. The isotope record spans between 1890 and 1994 AD. We explore the probable links between this record and the climate of the region. Air temperatures during summer conditions are significantly, but not strongly, inversely correlated with annual delta (18)O values from Austrocedrus tree rings. The strongest correlations are between the southern oscillation index (SOI) and the tree rings. The existence of millennial-age Austrocedrus trees in northern Patagonia provides interesting possibilities for examining these climate-related isotopic signals over most of the last 1,000 years.

  3. Stable isotopic studies on chitin. III. The D/H and 18O/ 16O ratios in arthropod chitin

    NASA Astrophysics Data System (ADS)

    Schimmelmann, Arndt; DeNiro, Michael J.

    1986-07-01

    Stable hydrogen and oxygen isotope ratios are presented for carbon-bound hydrogen and for oxygen in chitin-derived substrates from 57 arthropod species collected in 50 different locations or grown under controlled conditions in the laboratory. No systematic isotopic differences were found among Insecta, Crustacea, and Merostomata. The determination of infra- and interindividual isotopic variabilities in a lobster and among individuals of crustacean populations yielded small variances of about ±3 per mil for δD values and ±0.3 per mil for δ 18O values. Molting stage and sex of crustaceans showed no systematic effects on isotopic composition. The δD and δ 18O values of ambient water showed only weak correlations with the respective δ values of chitin-derived substrates. Positive correlation was observed between δD values and trophic level. No temperature effects on δ 18O and δD values from marine crustaceans were found that exceed the natural isotopic noise level. Taken together, these observations indicate that reconstruction of water isotopic composition from arthropod chitin δD and δ 18O values will require specific information about the habits and habitats of the species involved in the analysis.

  4. Stable isotope time-series in mammalian teeth: In situ δ18O from the innermost enamel layer

    NASA Astrophysics Data System (ADS)

    Blumenthal, Scott A.; Cerling, Thure E.; Chritz, Kendra L.; Bromage, Timothy G.; Kozdon, Reinhard; Valley, John W.

    2014-01-01

    Stable carbon and oxygen isotope ratios in mammalian tooth enamel are commonly used to understand the diets and environments of modern and fossil animals. Isotope variation during the period of enamel formation can be recovered by intra-tooth microsampling along the direction of growth. However, conventional sampling of the enamel surface provides highly time-averaged records in part due to amelogenesis. We use backscattered electron imaging in the scanning electron microscope (BSE-SEM) to evaluate enamel mineralization in developing teeth from one rodent and two ungulates. Gray levels from BSE-SEM images suggest that the innermost enamel layer, <20 μm from the enamel-dentine junction, is highly mineralized early in enamel maturation and therefore may record a less attenuated isotopic signal than other layers. We sampled the right maxillary incisor from a woodrat subjected to an experimentally induced water-switch during the period of tooth development, and demonstrate that secondary ion mass spectrometry (SIMS) can be used to obtain δ18O values with 4-5-μm spots from mammalian tooth enamel. We also demonstrate that SIMS can be used to discretely sample the innermost enamel layer, which is too narrow for conventional microdrilling or laser ablation. An abrupt δ18O switch of 16.0‰ was captured in breath CO2, a proxy for body water, while a laser ablation enamel surface intra-tooth profile of the left incisor captured a δ18O range of 12.1‰. The innermost enamel profile captured a δ18O range of 15.7‰, which approaches the full magnitude of δ18O variation in the input signal. This approach will likely be most beneficial in taxa such as large mammalian herbivores, whose teeth are characterized by less rapid mineralization and therefore greater attenuation of the enamel isotope signal.

  5. On the use of stable oxygen isotope18O) measurements for tracking avian movements in North America

    PubMed Central

    Hobson, Keith A; Koehler, Geoff

    2015-01-01

    Tracking migratory animals has benefitted using measurements of naturally occurring stable isotopes of hydrogen (δ2H) in keratinous tissues such as hair and feathers to link animal origins to continental patterns or isoscapes of δ2H in precipitation. However, for most taxa, much less information exists on the use of stable oxygen isotope ratios (δ18O) despite the fact that δ2H and δ18O are strongly linked in environmental waters through the meteoric relationship and the possibility of using both isotopes to infer greater information on origins and climatic conditions where tissues are grown. A fundamental requirement of using stable isotopes to assign individuals and populations to origins is the development of a rescaling function linking environmental food web signals to the tissue of interest and for birds, this has not been carried out. Here, we derived the relationship between H and O isotopes in known source feathers of 104 individuals representing 11 species of insectivorous passerines sampled across the strong precipitation isoscape of North America. We determined again a strong expected relationship between feather δ2H (δ2Hf) and long-term amount-weighted precipitation δ2H (δ2Hp; r2 = 0.77), but the corresponding relationship between δ18Of and δ18Op was poor (r2 = 0.32) for the same samples. This suggests that δ2H measurements are currently more useful for assignment of insectivorous songbirds to precipitation isoscapes but does not preclude other uses of the δ18Of data. Currently, mechanisms responsible for the decoupling of H and O isotopes in food webs is poorly known, and we advocate a much broader sampling of both isotopes in the same keratinous tissues across precipitation isotope gradients and across taxa to resolve this issue and to increase the power of using water isotopes to track migratory animals. PMID:25691999

  6. Stable Isotope (18O, 2H) and Arsenic Distribution in the Shallow Aquifers in Araihazar, Bangladesh

    NASA Astrophysics Data System (ADS)

    Zheng, Y.; Datta, S.; Stute, M.; Dhar, R.; Hoque, M. A.; Rahman, M. W.; Ahmed, K. M.; Schlosser, P.; van Geen, A.

    2005-12-01

    Recent estimates indicate that in Bangladesh alone, an estimated 50 million people have been exposed to Arsenic levels that exceed the WHO guideline of 10 μgL-1 for drinking water by up to two orders of magnitude. There is still debate on what processes control the spatial heterogeneity of dissolved As concentrations. One recent suggestion has been that surface waters enriched in labile organic matter and transferred to greater depths by irrigation pumping may be an important factor. We have monitored for a year the oxygen and hydrogen isotopic composition of precipitation in Dhaka, Bangladesh, and of surface waters and groundwaters in a 25 km2 study area in Araihazar, 20 km east of Dhaka. The data show a large spatial and temporal heterogeneity, with δ18O covering a range of up to 12 ‰. The isotopic composition of precipitation falls on the global meteoric water line (GMWL), while most surface waters collected from rivers, ponds and irrigated rice fields plot below and to the right of the meteoric water line, suggesting that evaporation is an important mechanism in this system. Surface waters show a strong evaporative enrichment during the dry season of up to 10 ‰ in δ18O and then show increased mixing with precipitation during the wet season. The groundwater isotopic composition obtained at 6 multi level well sites covers the range between the GMWL and moderately evaporated surface waters. These data indicate that some groundwaters are recharged directly by precipitation while others show evidence of recharge from evaporated surface waters during the wet and at the beginning of the dry season. For several well nests, the sources of groundwater vary in a systematic way as a function of depth. Highly evaporated irrigation water from rice fields in the dry season does not seem to contribute much to groundwater recharge. The degree of evaporation expressed as deuterium excess does not correlate with As concentrations in the groundwater samples. This finding

  7. Ontogeny and habitat change in Mesozoic cephalopods revealed by stable isotopes ( δ18O, δ13C)

    NASA Astrophysics Data System (ADS)

    Lukeneder, Alexander; Harzhauser, Mathias; Müllegger, Stefan; Piller, Werner E.

    2010-07-01

    Stable isotope ( δ18O and δ13C) ratios were measured in successive aragonitic shell sequences of ammonoids (class Cephalopoda) to determine whether their depth distributions changed within ontogeny and whether stable isotope values differ in various morphological groups (e.g. Leiostraca vs. Trachyostraca). We concentrate mainly on δ18O for temperature results and added δ13C data to obtain information on the ontogenetic history, for which full spiral measurements were undertaken for the first time. To obtain valid stable isotope data from ammonoid shells, we measured ontogenetic sequences (full shell) within different genera. Data sets from the Jurassic ( Cadoceras) and Cretaceous ( Hypacanthoplites, Nowakites) were chosen due to the pure primary aragonitic shell preservation. The study was designed to extract better information on the habitat and life cycle of fossil cephalopods (e.g. ammonoids) in comparison with recent cephalopods (e.g. Nautilus, Spirula, Sepia) possessing equivalent or comparable hard parts. The data from three genera suggest different modes of life in at least two morphological groups. We detected and established two main groups with different ontogenetic strategies based on the δ18O data. The wcw-type (warm-cool-warm type) of Cadoceras resembles strategies in Nautilus and Sepia, which migrate from shallow into deeper environments and back in ontogeny ( wc-type, warm-cool-type), and the cw-type (cool-warm type) of Hypacanthoplites resembling the first two migration phases of Spirula ( cwc-type), which migrates from deeper into shallower and back again into deeper habitats. The main (three) phases revealed by both δ18O and δ13C data sets most probably reflect diet changes in juvenile to mid-aged individuals, followed by a habitat change for spawning adults. In Cadoceras the temperatures range from 21.2 °C for juveniles down to 12.1 °C for mid-aged individuals and back up 16.9 °C in adults. The cw- type strategy of Hypacanthoplites

  8. The stable isotopic composition of a phosphorite deposit: δ13C, δ34S, and δ18O

    USGS Publications Warehouse

    Piper, D.Z.; Kolodny, Y.

    1987-01-01

    The stable isotopes of carbon and sulfur in a major marine sedimentary phosphate deposit from the northwestern United States (the Phosphoria Formation of Permian age) characterize the chemical properties of the depositional environment. The δ34S and δ13C analyses suggest deposition under conditions of variable redox from a solution the acidity of which was controlled by reaction with carbonate rocks and exchange with seawater. The δ18O concentration of apetite indicates phosphatization in a shallow sea, during three glacial and intervening interglacial stages. These data tend to corroborate the interpretation of field studies by others, that the apatite formed on a continental shelf in an area of intense oceanic upwelling during several episodes of sea level change. 

  9. Characterization of Growing Bacterial Populations in McMurdo Dry Valley Soils through Stable Isotope Probing with 18O-water

    PubMed Central

    Schwartz, Egbert; Buelow, Heather N.; Gooseff, Michael N.; Barrett, John E.; Okie, Jordan G.; Takacs-Vesbach, Cristina D.; Van Horn, David J.

    2014-01-01

    Soil microbial communities of the McMurdo Dry Valleys, Antarctica (MDV) contain representatives from at least fourteen bacterial phyla. However, given low rates of microbial activity, it is unclear whether this richness represents functioning rather than dormant members of the community. We used stable isotope probing (SIP) with 18O-water to determine if microbial populations grow in MDV soils. Changes in the microbial community were characterized in soils amended with H2 18O and H2 18O-organic matter. Sequencing the 16S rRNA genes of the heavy and light fractions of the bacterial community DNA show that DNA of microbial populations was labeled with 18O-water, indicating these microorganisms grew in the MDV soils. Significant differences existed in the community composition of the heavy and light fractions of the H2 18O and H2 18O-organic matter amended samples (Anosim P<0.05 of weighted Unifrac distance). Control samples and the light DNA fraction of the H2 18O amended samples were dominated by representatives of the phyla Deinococcus-Thermus, Proteobacteria, Planctomyces, Gemmatimonadetes, Actinobacteria and Acidobacteria, whereas Proteobacteria were more prevalent in the heavy DNA fractions from the H2 18O-water and the H2 18O-water-organic matter treatments. Our results indicate that SIP with H2 18O can be used to distinguish active bacterial populations even in this low organic matter environment. PMID:24785369

  10. Factors Influencing the Stable Oxygen and Hydrogen Isotopic Composition (δ 18O and δ D) of a Subarctic Freshwater Lake Ecosystem

    NASA Astrophysics Data System (ADS)

    Wang, Y.; Wooller, M. J.

    2005-12-01

    Previous studies have shown that the stable oxygen and hydrogen isotopic compositions (δ 18O and δD) in various animal tissues can be used to examine past climates and animal migration pattern. Little attention has been paid to the relative roles of diet and water influencing the overall δ 18O and δD of animal tissues in freshwater ecosystems. It is unclear whether different trophic levels in a freshwater lake ecosystem have an identical relationship to the water that surrounds them. The δ18O and δD values of animal tissues may be controlled by numerous different factors, including metabolic and biosynthetic isotopic fractionation and variations of δ 18O and δD in the food available. We began to examine these issues by analyzing the δ 18O and δD throughout a freshwater aquatic ecosystem at Smith Lake in Alaska. We collected samples representing primary producers and consumers (primary and secondary). Samples included green algae, various aquatic plants, such as Nuphar variegatum (water lily), Polygonum amphibium (water smartweed), Carex utriculata (sedge), Utricularia vulgaris (common bladderwort), Typha latifolia (common cattail), and a range of aquatic invertebrates, including Chironomus. sp (midge), Zygoptera (damselfly), Anisoptera (dragonfly), Dytiscidae (diving beetle) and Euhirudinea (leeches). The δ 18O and δD of Smith Lake water were ~-13.5e and -129.0e, respectively, and we present the δ 18O and δD of the rest of the ecosystem relative to these data. For instance, the δ 18O of chironomus sp. was ~12.1, which is greater than the of the lake water. Preliminary results suggest the extent of the fractionation between δ 18O of chironomids vs. lake water δ 18O is consistent with previous studies. Our data provide an insight into the range of variations that could be expected within a single freshwater ecosystem.

  11. Analysis of stable isotope ratios (δ18O and δ2H) in precipitation of the Verde River watershed, Arizona 2013 through 2014

    USGS Publications Warehouse

    Beisner, Kimberly R.; Paretti, Nicholas V.; Tucci, Rachel S.

    2016-01-01

    Stable isotope delta values (δ18O and δ2H) of precipitation can vary with elevation, and quantification of the precipitation elevation gradient can be used to predict recharge elevation within a watershed. Precipitation samples were analyzed for stable isotope delta values between 2003 and 2014 from the Verde River watershed of north-central Arizona. Results indicate a significant decrease in summer isotopic values overtime at 3,100-, 4,100-, 6,100-, 7,100-, and 8,100-feet elevation. The updated local meteoric water line for the area is δ2H = 7.11 δ18O + 3.40. Equations to predict stable isotopic values based on elevation were updated from previous publications in Blasch and others (2006), Blasch and Bryson (2007), and Bryson and others (2007). New equations were separated for samples from the Camp Verde to Flagstaff transect and the Prescott to Chino Valley transect. For the Camp Verde to Flagstaff transect, the new equations for winter precipitation are δ18O = -0.0004z − 8.87 and δ2H = -0.0029z − 59.8 (where z represents elevation in feet) and the summer precipitation equations were not statistically significant. For the Prescott to Chino Valley transect, the new equations for summer precipitation are δ18O = -0.0005z − 3.22 and δ2H = -0.0022z − 27.9; the winter precipitation equations were not statistically significant and, notably, stable isotope values were similar across all elevations. Interpretation of elevation of recharge contributing to surface and groundwaters in the Verde River watershed using the updated equations for the Camp Verde to Flagstaff transect will give lower elevation values compared with interpretations presented in the previous studies. For waters in the Prescott and Chino Valley area, more information is needed to understand local controls on stable isotope values related to elevation.

  12. Analysis of stable isotope ratios (δ18O and δ2H) in precipitation of the Verde River watershed, Arizona 2013 through 2014

    USGS Publications Warehouse

    Beisner, Kimberly R.; Paretti, Nicholas V.; Tucci, Rachel S.

    2016-04-25

    Stable isotope delta values (δ18O and δ2H) of precipitation can vary with elevation, and quantification of the precipitation elevation gradient can be used to predict recharge elevation within a watershed. Precipitation samples were analyzed for stable isotope delta values between 2003 and 2014 from the Verde River watershed of north-central Arizona. Results indicate a significant decrease in summer isotopic values overtime at 3,100-, 4,100-, 6,100-, 7,100-, and 8,100-feet elevation. The updated local meteoric water line for the area is δ2H = 7.11 δ18O + 3.40. Equations to predict stable isotopic values based on elevation were updated from previous publications in Blasch and others (2006), Blasch and Bryson (2007), and Bryson and others (2007). New equations were separated for samples from the Camp Verde to Flagstaff transect and the Prescott to Chino Valley transect. For the Camp Verde to Flagstaff transect, the new equations for winter precipitation are δ18O = -0.0004z − 8.87 and δ2H = -0.0029z − 59.8 (where z represents elevation in feet) and the summer precipitation equations were not statistically significant. For the Prescott to Chino Valley transect, the new equations for summer precipitation are δ18O = -0.0005z − 3.22 and δ2H = -0.0022z − 27.9; the winter precipitation equations were not statistically significant and, notably, stable isotope values were similar across all elevations. Interpretation of elevation of recharge contributing to surface and groundwaters in the Verde River watershed using the updated equations for the Camp Verde to Flagstaff transect will give lower elevation values compared with interpretations presented in the previous studies. For waters in the Prescott and Chino Valley area, more information is needed to understand local controls on stable isotope values related to elevation.

  13. Stable isotope18O and δ2H) data for precipitation, stream water, and groundwater in Puerto Rico

    USGS Publications Warehouse

    Scholl, Martha A.; Torres-Sanchez, Angel; Rosario-Torres, Manuel

    2014-01-01

    , hurricanes, and cold fronts, although frequent low-intensity orographic showers occur throughout the year in the mountains. The stable isotope signatures of rainfall (δ2H and δ18O) are broadly correlated with the weather type that produced the rainfall (Scholl and others, 2009; Scholl and Murphy, 2014).

  14. The stable isotopic composition of Daphnia ephippia reflects changes in δ13C and δ18O values of food and water

    NASA Astrophysics Data System (ADS)

    Schilder, J.; Tellenbach, C.; Möst, M.; Spaak, P.; van Hardenbroek, M.; Wooller, M. J.; Heiri, O.

    2015-06-01

    The stable isotopic composition of fossil resting eggs (ephippia) of Daphnia spp. is being used to reconstruct past environmental conditions in lake ecosystems. However, the underlying assumption that the stable isotopic composition of the ephippia reflects the stable isotopic composition of the parent Daphnia, of their diet and of the environmental water have yet to be confirmed in a controlled experimental setting. We performed experiments with Daphnia pulicaria cultures, which included a control treatment conducted at 12 °C in filtered lake water and with a diet of fresh algae and three treatments in which we manipulated the stable carbon isotopic composition (δ13C value) of the algae, stable oxygen isotopic composition (δ18O value) of the water and the water temperature, respectively. The stable nitrogen isotopic composition (δ15N value) of the algae was similar for all treatments. At 12 °C, differences in algal δ13C values and in δ18O values of water were reflected in those of Daphnia. The differences between ephippia and Daphnia stable isotope ratios were similar in the different treatments (δ13C: +0.2 ± 0.4 ‰ (standard deviation); δ15N: -1.6 ± 0.4 ‰; δ18O: -0.9 ± 0.4 ‰), indicating that changes in dietary δ13C values and in δ18O values of water are passed on to these fossilizing structures. A higher water temperature (20 °C) resulted in lower δ13C values in Daphnia and ephippia than in the other treatments with the same food source and in a minor change in the difference between δ13C values of ephippia and Daphnia (to -1.3 ± 0.3 ‰). This may have been due to microbial processes or increased algal respiration rates in the experimental containers, which may not affect Daphnia in natural environments. There was no significant difference in the offset between δ18O and δ15N values of ephippia and Daphnia between the 12 and 20 °C treatments, but the δ18O values of Daphnia and ephippia were on average 1.2 ‰ lower at 20 °C than at

  15. Stable isotope (2H, 17O, 18O) and hydro chemical patterns of precipitation collected in weekly resolution at Hannover, Germany

    NASA Astrophysics Data System (ADS)

    Koeniger, Paul; Himmelsbach, Thomas

    2016-04-01

    Long-term observations of stable isotopes18O and δ2H) in precipitation were initiated in May 2008 at the Federal Institute of Geosciences and Natural Resources (BGR) in Hannover, Germany. In 2014 all precipitation samples were re-analyzed because a purchase of a new laser spectrometer (Picarro L2140-i) now allowed measurements of δ17O and a calculation of the 17O-excess parameter. Starting in October 2015 a routine analysis of hydro chemical parameters was added whenever enough sample aliquot was available (major ions, trace elements). A discussion of the stable isotope data of the seven year series of weekly precipitation samples (n = 370) will be presented. Beneath general patterns (seasonality and trends) we also focus on importance of amount weighing procedures, corrections for minor rain amounts, aspects of sample storage and re-analyzes, as well as impacts through changes in analytical equipment (IRMS, CRD spectroscopy) which is visible from the data. For stable isotopes a Thermo Fisher delta plus IRMS (Gasbench and H-Device) was used until 2011 and from 2012 on a Picarro L2120-i water vapor analyzer with long-term accuracies for quality check samples better than 0.2‰ and 0.8‰ for δ18O and δ2H, respectively.

  16. Stable Oxygen (δ 18O) and Carbon (δ 13C) Isotopes in the Skeleton of Bleached and Recovering Corals From Hawaii

    NASA Astrophysics Data System (ADS)

    Rodrigues, L. J.; Grottoli, A. G.

    2004-12-01

    Coral skeletal stable oxygen isotopes18O) reflect changes in seawater temperature and salinity, while stable carbon isotopes (δ 13C) reflect a combination of both metabolic (photosynthesis and feeding) and kinetic fractionation. Together, the two isotopic signatures may be used as a proxy for past bleaching events. During bleaching, increased seawater temperatures often contribute to a decline in zooxanthellae and/or chlorophyll concentrations, resulting in a decrease in photosynthesis. We experimentally investigated the effect of bleaching and subsequent recovery on the δ 13C and δ 18O values of coral skeleton. Fragments from two coral species (Montipora capitata and Porites compressa) from Kaneohe Bay, Hawaii were bleached in outdoor tanks by raising the seawater temperature to 30° C. Additional fragments from the same parent colonies were maintained at ambient seawater temperatures (27° C) in separate tanks as controls. After one month in the tanks, a subset of the fragments was frozen and all remaining fragments were placed back on the reef to recover. All coral fragments were analyzed for their skeletal δ 13C and δ 18O compositions at five time intervals: before, immediately after, 1.5, 4, and 8 months after bleaching. In addition, rates of photosynthesis, calcification, and heterotrophy were also measured. Immediately after bleaching, δ 18O decreased in bleached M. capitata relative to controls, reflecting their exposure to increased seawater temperatures. During recovery, δ 18O values in the treatment M. capitata were not different from the controls. In P. compressa, δ 18O did not significantly differ in bleached and control corals at any time during the experiment. Immediately after bleaching, δ 13C decreased in the bleached fragments of both species relative to controls reflecting decreased photosynthetic rates. However, during recovery δ 13C in both species was greater in bleached than control fragments despite photosynthesis remaining

  17. Use of 2H and 18O stable isotopes to investigate water sources for different ages of Populus euphratica along the lower Heihe River

    USGS Publications Warehouse

    Shubao Liu,; Yaning Chen,; Yapeng Chen,; Friedman, Jonathan M.; Gonghuan Fan,; Hati, Jarre Heng A.

    2015-01-01

    Investigation of the water sources used by trees of different ages is essential to formulate a conservation strategy for the riparian tree, P. euphratica. This study addressed the contributions of different potential water sources to P. euphratica based on levels of stable oxygen and hydrogen isotopes18O, δ2H) in the xylem of different aged P. euphratica, as well as in soil water and groundwater along the lower Heihe River. We found significant differences in δ18O values in the xylem of different aged P. euphratica. Specifically, the δ18O values of young, mature and over-mature forests were −5.368(±0.252) ‰, −6.033(± 0.185) ‰ and −6.924 (± 0.166) ‰, respectively, reflecting the reliance of older trees on deeper sources of water with a δ18O value closer to that of groundwater. Different aged P. euphratica used different water sources, with young forests rarely using groundwater (mean <15 %) and instead primarily relying on soil water from a depth of 0–50 cm (mean >45 %), and mature and over-mature forests using water from deeper than 100 cm derived primarily from groundwater.

  18. UV-laser microdissection system - A novel approach for the preparation of high-resolution stable isotope records (δ13C/δ18O) from tree rings

    NASA Astrophysics Data System (ADS)

    Schollaen, Karina; Helle, Gerhard

    2013-04-01

    Intra-annual stable isotope (δ13C and δ18O) studies of tree rings at various incremental resolutions have been attempting to extract valuable seasonal climatic and environmental information or assessing plant ecophysiological processes. For preparing high-resolution isotope samples normally wood segments or cores are mechanically divided in radial direction or cut in tangential direction. After mechanical dissection, wood samples are ground to a fine powder and either cellulose is extracted or bulk wood samples are analyzed. Here, we present a novel approach for the preparation of high-resolution stable isotope records from tree rings using an UV-laser microdissection system. Firstly, tree-ring cellulose is directly extracted from wholewood cross-sections largely leaving the wood anatomical structure intact and saving time as compared to the classical procedure. Secondly, micro-samples from cellulose cross-sections are dissected with an UV-Laser dissection microscope. Tissues of interest from cellulose cross-sections are identified and marked precisely with a screen-pen and dissected via an UV-laser beam. Dissected cellulose segments were automatically collected in capsules and are prepared for stable isotope (δ13C and δ18O) analysis. The new techniques facilitate inter- and intra-annual isotope analysis on tree-ring and open various possibilities for comparisons with wood anatomy in plant eco-physiological studies. We describe the design and the handling of this novel methodology and discuss advantages and constraints given by the example of intra-annual oxygen isotope analysis on tropical trees.

  19. Localization of groundwater infiltration in the combined sewers of Brussels by stable isotopes measurements (δ18O, δD) by Cavity Ring Down Spectroscopy.

    NASA Astrophysics Data System (ADS)

    De Bondt, Kevin; Claeys, Philippe

    2014-05-01

    In the last 20 years research has been conducted to quantify the infiltration of groundwater into the sewers. This groundwater, called parasitic water, increases the volume of waste-water to be treated and consequently the cost of this treatment. Moreover, in the case of combined sewer systems, the parasitic water also limits the sewer capacity and indirectly increases the risks of combined sewer overflows and floods. The infiltration of groundwater occurs trough cracks, sewer collapses and from direct connections with old springs. Different methods quantify the intrusion of parasitic water. Among these, the use of the stable isotopes of water (δ18O & δD) shows good result in catchments or cities close to Mountainous regions (example from Lyon, Zurich), where isotopic signals vary significantly because of continental and altitude effects. However many cities, such as Brussels, are located in more oceanic settings and theoretically offer less potential for the application of the stable isotopes method. In the case of Brussels, river-water from the Meuse is used to produce domestic-water. The catchment of this river extends into the Ardennes, which are affected by slightly different climatic conditions. δ18O & δD analyzes of groundwater from the main aquifer (Ledo-Paniselian-Brusselian) and domestic-water from the Callois reservoir fed by the Meuse River show sufficient isotopic differences in the south of Brussels, but only during the summer. The discrimination potential is better with δD than with δ18O. The improvement of δD measurements (precision, costs,...) brought by Cavity Ring Down Spectroscopy largely contributes to the potential of using stable isotopes method to trace water in Brussels. The first campaigns in the sewers also show a little enrichment (in heavy isotopes) of the waste-water in comparison with the reservoir waters and tap waters. This increases the potential of the method but constrains the sampling to pure waste-water in sewer segments

  20. Prediction of plant vulnerability to salinity increase in a coastal ecosystem by stable isotopic composition (δ18O) of plant stem water: a model study

    USGS Publications Warehouse

    Zhai, Lu; Jiang, Jiang; DeAngelis, Don; Sternberg, Leonel d.S.L

    2016-01-01

    Sea level rise and the subsequent intrusion of saline seawater can result in an increase in soil salinity, and potentially cause coastal salinity-intolerant vegetation (for example, hardwood hammocks or pines) to be replaced by salinity-tolerant vegetation (for example, mangroves or salt marshes). Although the vegetation shifts can be easily monitored by satellite imagery, it is hard to predict a particular area or even a particular tree that is vulnerable to such a shift. To find an appropriate indicator for the potential vegetation shift, we incorporated stable isotope 18O abundance as a tracer in various hydrologic components (for example, vadose zone, water table) in a previously published model describing ecosystem shifts between hammock and mangrove communities in southern Florida. Our simulations showed that (1) there was a linear relationship between salinity and the δ18O value in the water table, whereas this relationship was curvilinear in the vadose zone; (2) hammock trees with higher probability of being replaced by mangroves had higher δ18O values of plant stem water, and this difference could be detected 2 years before the trees reached a tipping point, beyond which future replacement became certain; and (3) individuals that were eventually replaced by mangroves from the hammock tree population with a 50% replacement probability had higher stem water δ18O values 3 years before their replacement became certain compared to those from the same population which were not replaced. Overall, these simulation results suggest that it is promising to track the yearly δ18O values of plant stem water in hammock forests to predict impending salinity stress and mortality.

  1. Trends in nitrate concentrations and determination of its origin using stable isotopes (18O and 15N) in groundwater of the Western Central Valley, Costa Rica.

    PubMed

    Reynolds-Vargas, Jenny; Fraile-Merino, Julio; Hirata, Ricardo

    2006-08-01

    A study was conducted to evaluate long-term trends in nitrate concentrations and to try to identify the origin of nitrate using stable isotopes (15N(NO3-) and 18O(NO3-)) in the aquifers of the western Central Valley, Costa Rica, where more than 1 million people depend on groundwater to satisfy their daily needs. Data from 20 sites periodically sampled for 4 to 17 years indicate an increasing trend in nitrate concentrations at five sites, which in a period ranging from 10 to 40 years, will exceed recommended maximum concentrations. Results of isotopic analysis indicate a correspondence between land use patterns and the isotopic signature of nitrate in groundwater and suggest that urbanization processes without adequate waste disposal systems, followed by coffee fertilization practices, are threatening water quality in the region. We conclude that groundwater management in this area is not sustainable, and that land use substitution processes from agricultural activity to residential occupation that do not have proper sewage disposal systems may cause a significant increment in the nitrate contaminant load. PMID:16989507

  2. Growth Rates, Stable Oxygen Isotopes (18O), and Strontium (Sr/Ca) Composition in Two Species of Pacific Sclerosponges (Acanthocheatetes wellsi and Astrosclera willeyana) with 18O Calibration and Application to Paleoceanography

    SciTech Connect

    Grottoli, A.; Adkins, J; Panero, W; Reaman, D; Moots, K

    2010-01-01

    The isotopic and elemental composition of sclerosponge skeletons is used to reconstruct paleoceanographic records. Yet few studies have systematically examined the natural variability in sclerosponge skeletal {delta}{sup 18}O, growth, and Sr/Ca, and how that may influence the interpretation of sclerosponge proxy records. Here, we analyzed short records in seven specimens of Acanthocheatetes wellsi (high-Mg calcite, 21 mol% Mg) from Palau, four A. wellsi (high-Mg calcite, 21 mol% Mg) from Saipan, and three Astrosclera willeyana (aragonite) sclerosponges from Saipan, as well as one long record in an A. wellsi specimen from Palau spanning 1945-2001.5. In Saipan, species-specific and mineralogical effects appear to have a negligible effect on sclerosponge {delta}{sup 18}O, facilitating the direct comparison of {delta}{sup 18}O records between species at a given location. At both sites, A. wellsi {delta}{sup 18}O and growth rates were sensitive to environmental conditions, but Sr/Ca was not sensitive to the same conditions. High-resolution {delta}{sup 18}O analyses confirmed this finding as both A. wellsi and A. willeyana deposited their skeleton in accordance with the trends in isotopic equilibrium with seawater, though with a 0.27{per_thousand} offset in the case of A. willeyana. In the high-Mg-calcite species A. wellsi, Mg may be interfering with Sr incorporation into the skeleton. On multidecadal timescales, A. wellsi sclerosponge {delta}{sup 18}O in Palau tracked the Southern Oscillation Index variability post-1977, but not pre-1977, coincident with the switch in the Pacific Decadal Oscillation (PDO) at {approx}1976. This suggests that water mass circulation in the region is influenced by El Nino-Southern Oscillation variability during positive PDO phases, but not during negative ones.

  3. Stable Isotope Values of the Mesoamerican Monsoon: δ18O and δ2H Values Reveal Climate Controls on Summer Rainfall Amount

    NASA Astrophysics Data System (ADS)

    Bernal, J. P.; Lachniet, M. S.; Rosales Lagarde, L.; Morales Puente, P.; Cienfuegos, E.

    2014-12-01

    Paleoclimate reconstructions using δ18O as a proxy for the isotopic composition of rainfall are based upon the mostly untested assumption that either rainfall amount or equilibration temperature are the main drivers modulating the isotopic composition of pluvial precipitation. Whilst a broad correlation between geographical location and driving mechanisms has been long recognized (i.e. amount effect is pervasive in tropical areas), further tests are required to determine the effect that different sources of moisture might impose on the isotopic composition of precipitation, particularly in areas where contributions from different ocean-basins might be significant, such as south Mexico. Here, we present the δ18O and δ2H composition of summer rainfall collected throughout south, central and western Mexico, particularly from Veracruz, Puebla, Guerrero, Morelos, Mexico City, Jalisco, Michoacán and Querétaro states. The geographical and temporal extent of our sampling (2004, 2005, 2007, 2008, 2011) results in a large dataset comprising more than 600 samples and represents the base data to understand the atmospheric mechanisms modulating the isotopic composition of rainfall in Mexico. Our data span a range of 30‰ in δ18O, from high values nearest the Gulf of Mexico coast and during weak rainfall events, to lowest values in high-altitude central Mexico and during heavy rainfall events associated with tropical cyclones. Values on the Pacific Coast are intermediate, and likely reflect a contribution of both Gulf of Mexico and Pacific sources. Our data define a meteoric water line of δ2H = 7.92 × δ18O + 9.48, which indicate that most precipitation values formed close to isotopic equilibrium with water vapor. The two primary physiographic variables controlling δ18O values are distance from the Gulf of Mexico and altitude, which together explain about 70% of the variation in spatial δ18O values.

  4. A conifer-friendly high-throughput α-cellulose extraction method for δ13C and δ18O stable isotope ratio analysis

    NASA Astrophysics Data System (ADS)

    Lin, W.; Noormets, A.; domec, J.; King, J. S.; Sun, G.; McNulty, S.

    2012-12-01

    Wood stable isotope ratios (δ13C and δ18O) offer insight to water source and plant water use efficiency (WUE), which in turn provide a glimpse to potential plant responses to changing climate, particularly rainfall patterns. The synthetic pathways of cell wall deposition in wood rings differ in their discrimination ratios between the light and heavy isotopes, and α-cellulose is broadly seen as the best indicator of plant water status due to its local and temporal fixation and to its high abundance within the wood. To use the effects of recent severe droughts on the WUE of loblolly pine (Pinus taeda) throughout Southeastern USA as a harbinger of future changes, an effort has been undertaken to sample the entire range of the species and to sample the isotopic composition in a consistent manner. To be able to accommodate the large number of samples required by this analysis, we have developed a new high-throughput method for α-cellulose extraction, which is the rate-limiting step in such an endeavor. Although an entire family of methods has been developed and perform well, their throughput in a typical research lab setting is limited to 16-75 samples per week with intensive labor input. The resin exclusion step in conifersis is particularly time-consuming. We have combined the recent advances of α-cellulose extraction in plant ecology and wood science, including a high-throughput extraction device developed in the Potsdam Dendro Lab and a simple chemical-based resin exclusion method. By transferring the entire extraction process to a multiport-based system allows throughputs of up to several hundred samples in two weeks, while minimizing labor requirements to 2-3 days per batch of samples.

  5. Application of (15)N- (18)O double stable isotope tracer technique in an agricultural nonpoint polluted river of the Yangtze Delta Region.

    PubMed

    Liang, X Q; Nie, Z Y; He, M M; Guo, R; Zhu, C Y; Chen, Y X; Stephan, Küppers

    2013-10-01

    One strategy to combat nitrate (NO3-N) contamination in rivers is to understand its sources. NO3-N sources in the East Tiaoxi River of the Yangtze Delta Region were investigated by applying a (15)N-(18)O dual isotope approach. Water samples were collected from the main channel and from the tributaries. Results show that high total N and NO3-N are present in both the main channel and the major tributaries, and NO3-N was one of the most important N forms in water. Analysis of isotopic compositions (δ (18)O, δD) of water suggests that the river water mainly originated from three tributaries during the sampling period. There was a wide range of δ (15)N-NO3 (-1.4 to 12.4 ‰) and a narrow range of δ (18)O-NO3 (3.7 to 9.0 ‰) in the main channel waters. The δ (15)N and δ (18)O-NO3 values in the upper, middle, and lower channels along the river were shifted as 8.2, 3.5, and 9.5 ‰, and 9.0, 4.2, and 6.0 ‰, respectively. In the tributary South Tiao, the δ (15)N and δ (18)O-NO3 values were as high as 9.5 and 7.0 ‰, while in the tributaries Mid Tiao and North Tiao, NO3-N in most of the samples had relatively low δ (15)N and δ (18)O-NO3 values from 2.3 to 7.5 ‰ and 4.7 to 7.0 ‰, separately. Our results also suggest that the dual isotope approach can help us develop the best management practice for relieving NO3-N pollution in the rivers at the tributary scale.

  6. Using Halogens (Cl, Br, F, I) and Stable Isotopes of Water (δ18O, δ2H) to Trace Hydrological and Biogeochemical Processes in Prairie Wetlands

    NASA Astrophysics Data System (ADS)

    Levy, Z. F.; Lu, Z.; Mills, C. T.; Goldhaber, M. B.; Rosenberry, D. O.; Mushet, D.; Siegel, D. I.; Fiorentino, A. J., II; Gade, M.; Spradlin, J.

    2014-12-01

    Prairie pothole wetlands are ubiquitous features of the Great Plains of North America, and important habitat for amphibians and migratory birds. The salinity of proximal wetlands varies highly due to groundwater-glacial till interactions, which influence wetland biota and associated ecosystem functions. Here we use halogens and stable isotopes of water to fingerprint hydrological and biogeochemical controls on salt cycling in a prairie wetland complex. We surveyed surface, well, and pore waters from a groundwater recharge wetland (T8) and more saline closed (P1) and open (P8) basin discharge wetlands in the Cottonwood Lake Study Area (ND) in August/October 2013 and May 2014. Halogen concentrations varied over a broad range throughout the study area (Cl = 2.2 to 170 mg/L, Br = 13 to 2000 μg/L, F = < 30 (MDL) to 740 μg/L, I = 1 to 538 μg/L). The Cl/Br molar ratios were higher (171 to 574) at the recharge wetland, indicating meteoric sources, and had a tighter and lower range (33 to 320) at the down-gradient sites. The Cl/I molar ratios of waters throughout the site had a wide range (32 to 26,000). Lowest values occurred at the upgradient shore of P1 (32 to 43) due to low Cl concentrations and the center of P1 (196 to 213) where pore water of weathered till underlying 1.2 m of organic-rich sediment and silty clay soil is enriched in I to ~500 µg/L. Stable isotopes of water showed that evaporation-enriched pond water (δ18O = -9.5 to -2.71 ‰) mixes with shallow groundwater in the top 0.6 m of fringing wetland soils and 1.2 m of the substrate in the center of P1. Our results suggest endogenous sources for Br and I within the prairie landscape that may be controlled by biological mechanisms or weathering of shale from glacial till.

  7. The distribution of radioactive ( 3H, 14C) and stable ( 2H, 18O) isotopes in precipitation, surface and groundwaters of NW Yugoslavia

    NASA Astrophysics Data System (ADS)

    Horvatinčić, Nada; Krajcar-Bronić, Ines; Pezdič, Jože; Srdoč, Dušan; Obelić, Bogomil

    1986-11-01

    The isotopic measurements ( 2H, 3H, 18O) of precipitiation in Zagreb (since 1976) and Ljubljana (since 1981) in NW Yugoslavia show seasonal variations typical of the Northern hemisphere. Continuous measurements of tritium concentration in the Sava River ca 10 km upstream from Zagreb have been performed since 1976. Data show a smooth line without periodical changes, but a steady decrease is obvious. The sampling place is situated ca 30 km downstream from the Kr\\vsko Nuclear Power Plant. No change in tritium concentration due to the operation of the power plant has been observed. A comprehensive program of monitoring of the 14C activity in air CO 2 as well as in vegetables, cereals and tree-rings in the surroundings of the Nuclear Power Plant Kr\\vsko has been carried out since 1984. The measurement of 2H and 18O in karst springs of the Korana River catchmet area (Plitvice National Park) gave a meteoric water line equal to δ2H = 7.9 δ18O + 8.5, which is typical of the NW part of Yugoslavia. A fairly constant concentration of 2H and 18O in spring water indicates a thorough mixing of water in the karst aquifers. The mean residence time (MRT) of karst water was determined by measuring monthly tritium activity of spring water. The MRT is very short, ranging between 1 and 4 years on average.

  8. Stable isotopes18O and δ 13C), trace and minor element compositions of Recent scleractinians and Last Glacial bivalves at the Santa Maria di Leuca deep-water coral province, Ionian Sea

    NASA Astrophysics Data System (ADS)

    Correa, Matthias López; Montagna, Paolo; Vendrell-Simón, Begoña; McCulloch, Malcolm; Taviani, Marco

    2010-03-01

    The aragonitic skeletons of bathyal cold-water corals have a high potential as geochemical in situ archives for paleoceanography. Oxygen isotopes and stable carbon isotopes18O and δ 13C) have been analyzed, as well as trace and minor element compositions (e.g. Mg/Ca, Sr/Ca, U/Ca, B/Ca and P/Ca) in Lophelia pertusa, one of the most important frame-builders at the Santa Maria di Leuca (SML) deep-water coral hotspot in the Central Mediterranean. The Apulian Bank is swept by strong currents of the Adriatic Deep Water Outflow. The temperature of 13.9 °C is the highest temperature recorded for L. pertusa and provides an important end-member of environmental conditions for geochemical analyses on living Atlantic and Mediterranean cold-water corals. Temperature and salinity (38.77 PSU) are stable throughout the year, and thus virtually no changes should be observed in the stable oxygen isotope signal—if the coral precipitates its skeleton in equilibrium with seawater. We measured various marine properties, such as the seawater oxygen isotope composition (δ 18O sw), stable carbon isotope composition (δ 13C DIC) of dissolved inorganic carbon (DIC), and dissolved inorganic nutrient concentrations (PO 4, NO 3, NO 2, NH 3 and SiO 2). Bottom water at the coral sites shows a mean oxygen isotope composition of 1.47‰ δ 18O sw-VSMOW, and δ 13C DIC showed a mean of 1.1‰ VPDB. A section of a living L. pertusa with a thick theca calcification was probed with a Merchantek MicroMill at a high spatial sampling resolution with 10 samples per 1 mm. This reduced the signal-smoothing inherent to conventional sampling. The δ 18O ag of coral aragonite ranges between -2.0‰ and +2.8‰ VPDB and the δ 13C ag ranges between -7.77‰ and +1.47‰ VPDB. The Gaussian data distribution for both parameters, including heavy equilibrium values, suggests the completeness of the captured isotopic variability. The strict linear correlation of δ 13C and δ 18O displays a strong 'kinetic

  9. The value of stable Isotope (18O) and electrical conductivity (EC) as tracers for submarine Groundwater exfiltration and density-driven flow infiltration into the aquifer.

    NASA Astrophysics Data System (ADS)

    Müller, Sascha; Engesgaard, Peter; Duque, Carlos; Jessen, Søren; Sonnenborg, Torben; Stau, Joakim; Neilson, Bethany

    2015-04-01

    Saltwater intrusion (SWI) into a freshwater aquifer is a dynamic process due to e.g. natural changes in sea levels (tides) and recharge. Coastal lagoons, on the other hand, are often controlled water bodies where the water level and salinity are managed by the operation of a sluice connecting the lagoon to the ocean. This study describes the seasonal dynamics of the saltwater/freshwater interface and submarine groundwater discharge (SGD) patterns at a coastal lagoon on the West coast of Denmark. Here the salinity of the lagoon is high in the summer period, where recharge is low (favoring SWI) and vice versa in the winter time. SGD was measured over four seasons in 2012 along two transects. 18O and electrical conductivity (EC) were measured at the same time to a depth of 3.5 m with a sample interval of 0.25 m. In September 2014 a transect with 12 piezometers (screening depth between 1.5 and 15 m below surface) and one profile well (with measurements every 1 m down to 15 m) was established across the saltwater/freshwater interface at one of the transects. 18O and EC were measured and each piezometer was equipped with a CTD-diver measuring pressure head, temperature, and EC in the period switching from summer to winter conditions. Although 18O and EC is relatively well correlated (correlation coefficient of 0.8) the use of both tracers are recommend for this type of environment. Salinity (or EC) in the lagoon changes seasonally, whereas 18O in both lagoon water and groundwater is relatively stable within each end- member, suggesting that 18O is the tracer to prefer. However, on the other hand EC is an easy and in-expensive (continuous) measurement allowing a much better resolution in both space and time. The combination of both tracers can improve the explanation of the origin of water with more certainty. Both tracers show a seasonal interplay between freshwater discharge into the lagoon and a density- driven recycling with opposing flow into the aquifer. 18O and EC

  10. Sauna, sweat and science - quantifying the proportion of condensation water versus sweat using a stable water isotope ((2)H/(1)H and (18)O/(16)O) tracer experiment.

    PubMed

    Zech, Michael; Bösel, Stefanie; Tuthorn, Mario; Benesch, Marianne; Dubbert, Maren; Cuntz, Matthias; Glaser, Bruno

    2015-01-01

    Most visitors of a sauna appreciate the heat pulse that is perceived when water is poured on the stones of a sauna stove. However, probably only few bathers are aware that this pleasant heat pulse is caused by latent heat being released onto our skin due to condensation of water vapour. In order to quantify the proportion of condensation water versus sweat to dripping water of test persons we conducted sauna experiments using isotopically labelled (δ(18)O and δ(2)H) thrown water as tracer. This allows differentiating between 'pure sweat' and 'condensation water'. Two ways of isotope mass balance calculations were applied and yielded similar results for both water isotopes. Accordingly, condensation contributed considerably to dripping water with mean proportions of 52 ± 12 and 54 ± 7% in a sauna experiment in winter semester 2011/12 and 30 ± 13 and 33 ± 6% in a sauna experiment in winter semester 2012/13, respectively, depending on the way of calculating the isotope mass balance. It can be concluded from the results of our dual isotope labelling sauna experiment that it is not all about sweat in the sauna.

  11. Sauna, sweat and science - quantifying the proportion of condensation water versus sweat using a stable water isotope ((2)H/(1)H and (18)O/(16)O) tracer experiment.

    PubMed

    Zech, Michael; Bösel, Stefanie; Tuthorn, Mario; Benesch, Marianne; Dubbert, Maren; Cuntz, Matthias; Glaser, Bruno

    2015-01-01

    Most visitors of a sauna appreciate the heat pulse that is perceived when water is poured on the stones of a sauna stove. However, probably only few bathers are aware that this pleasant heat pulse is caused by latent heat being released onto our skin due to condensation of water vapour. In order to quantify the proportion of condensation water versus sweat to dripping water of test persons we conducted sauna experiments using isotopically labelled (δ(18)O and δ(2)H) thrown water as tracer. This allows differentiating between 'pure sweat' and 'condensation water'. Two ways of isotope mass balance calculations were applied and yielded similar results for both water isotopes. Accordingly, condensation contributed considerably to dripping water with mean proportions of 52 ± 12 and 54 ± 7% in a sauna experiment in winter semester 2011/12 and 30 ± 13 and 33 ± 6% in a sauna experiment in winter semester 2012/13, respectively, depending on the way of calculating the isotope mass balance. It can be concluded from the results of our dual isotope labelling sauna experiment that it is not all about sweat in the sauna. PMID:26110629

  12. Field calibration of stable isotopes18O) in coccoliths : Toward an accurate carbonate record-based reconstruction of the photic zone temperature

    NASA Astrophysics Data System (ADS)

    Candelier, Y.; Minoletti, F.; Hermoso, M.; Probert, I.

    2010-12-01

    Oxygen-isotopes from biogenic carbonates have been widely used to estimate SSTs during the Cenozoic. The full potential of coccolithophores for reconstructing past temperatures is still unexploited owing to two major issues: their minute size that prevents their isotopic analyzes at the specific level as done for foraminifera, and the large range of interspecific isotopic offsets (~ 5‰) ascribed to the vital effect (Ziveri et al., 2003). To test the suitability of applying in vitro data for the truly pelagic natural record, we established new coccolithophorid δ18O-temperature calibrations from sediments that we compared to empirical thermodependance equations from previous culture experiments. In this respect, we focused on two foremost coccolithophore species: Calcidicus leptoporus and Gephyrocapsa oceanica. We successfully obtained monospecific fractions of those taxa by applying a microfiltering protocol (Minoletti et al., 2009) on Holocene sediments for which the temperature of the photic zone water has been directly measured. For G. oceanica, the constant offset (δcGo-δceq) of ~ +1.5‰ with respect to equilibrium is in a good agreement with previous culture experiments (~ +1.6‰; Ziveri et al., 2003). Conversely, for C. leptoporus, although the relation between temperature and oxygen-isotopic fractionation is also well-behaved between 16 and 27°C, we found a significant discrepancy with previous cultures (-2.8‰; Dudley et al., 1986). This difference could be the result of growing conditions in the lab that may not mimate the natural environment (seawater chemistry such as pH, nutrient level, cell concentration, …). We generated new isotopic results of preliminary temperature-controlled experiments for C. leptoporus in constrained conditions close to the natural environment. We measured an isotopic offset comparable to the one from our sedimentologic study. Hence, we suggest a new correction of -1.2‰ for C. leptoporus, which may be more

  13. Life history of the individuals buried in the St. Benedict Cemetery (Prague, 15th-18th centuries): insights from (14)C dating and stable isotope (δ(13)C, δ(15)N, δ(18)O) analysis.

    PubMed

    Salesse, Kevin; Dufour, Élise; Castex, Dominique; Velemínský, Petr; Santos, Frédéric; Kuchařová, Hedvika; Jun, Libor; Brůžek, Jaroslav

    2013-06-01

    Funerary practices and bioarchaeological (sex and age) data suggest that a mortality crisis linked to an epidemic episode occurred during the fifth phase of the St. Benedict cemetery in Prague (Czech Republic). To identify this mass mortality episode, we reconstructed individual life histories (dietary and mobility factors), assessed the population's biological homogeneity, and proposed a new chronology through stable isotope analysis (δ(13)C, δ(18)O and δ(15)N) and direct radiocarbon dating. Stable isotope analysis was conducted on the bone and tooth enamel (collagen and carbonate) of 19 individuals from three multiple graves (MG) and 12 individuals from individual graves (IG). The δ(15)N values of collagen and the difference between the δ(13)C values of collagen and bone carbonate could indicate that the IG individuals had a richer protein diet than the MG individuals or different food resources. The human bone and enamel carbonate and δ(18)O values suggest that the majority of individuals from MG and all individuals from IG spent most of their lives outside of the Bohemian region. Variations in δ(18)O values also indicate that all individuals experienced residential mobility during their lives. The stable isotope results, biological (age and sex) data and eight (14)C dates clearly differentiate the MG and IG groups. The present work provides evidence for the reuse of the St. Benedict cemetery to bury soldiers despite the funeral protest ban (1635 AD). The Siege of Prague (1742 AD) by French-Bavarian-Saxon armies is identified as the cause of the St. Benedict mass mortality event.

  14. Life history of the individuals buried in the St. Benedict Cemetery (Prague, 15th-18th centuries): insights from (14)C dating and stable isotope (δ(13)C, δ(15)N, δ(18)O) analysis.

    PubMed

    Salesse, Kevin; Dufour, Élise; Castex, Dominique; Velemínský, Petr; Santos, Frédéric; Kuchařová, Hedvika; Jun, Libor; Brůžek, Jaroslav

    2013-06-01

    Funerary practices and bioarchaeological (sex and age) data suggest that a mortality crisis linked to an epidemic episode occurred during the fifth phase of the St. Benedict cemetery in Prague (Czech Republic). To identify this mass mortality episode, we reconstructed individual life histories (dietary and mobility factors), assessed the population's biological homogeneity, and proposed a new chronology through stable isotope analysis (δ(13)C, δ(18)O and δ(15)N) and direct radiocarbon dating. Stable isotope analysis was conducted on the bone and tooth enamel (collagen and carbonate) of 19 individuals from three multiple graves (MG) and 12 individuals from individual graves (IG). The δ(15)N values of collagen and the difference between the δ(13)C values of collagen and bone carbonate could indicate that the IG individuals had a richer protein diet than the MG individuals or different food resources. The human bone and enamel carbonate and δ(18)O values suggest that the majority of individuals from MG and all individuals from IG spent most of their lives outside of the Bohemian region. Variations in δ(18)O values also indicate that all individuals experienced residential mobility during their lives. The stable isotope results, biological (age and sex) data and eight (14)C dates clearly differentiate the MG and IG groups. The present work provides evidence for the reuse of the St. Benedict cemetery to bury soldiers despite the funeral protest ban (1635 AD). The Siege of Prague (1742 AD) by French-Bavarian-Saxon armies is identified as the cause of the St. Benedict mass mortality event. PMID:23588853

  15. Complete Measurement of Stable Isotopes in N2O (δ15N, δ15Nα, δ15Nβ, δ18O, δ17O) Using Off-Axis Integrated Cavity Output Spectroscopy (OA-ICOS)

    NASA Astrophysics Data System (ADS)

    Leen, J. B.; Gupta, M.

    2014-12-01

    Nitrate contamination in water is a worldwide environmental problem and source apportionment is critical to managing nitrate pollution. Fractionation caused by physical, chemical and biological processes alters the isotope ratios of nitrates (15N/14N, 18O/16O and 17O/16O) and biochemical nitrification and denitrification impart different intramolecular site preference (15N14NO vs. 14N15NO). Additionally, atmospheric nitrate is anomalously enriched in 17O compared to other nitrate sources. The anomaly (Δ17O) is conserved during fractionation processes, providing a tracer of atmospheric nitrate. All of these effects can be used to apportion nitrate in soil. Current technology for measuring nitrate isotopes is complicated and costly - it involves conversion of nitrate to nitrous oxide (N2O), purification, preconcentration and measurement by isotope ratio mass spectrometer (IRMS). Site specific measurements require a custom IRMS. There is a pressing need to make this measurement simpler and more accessible. Los Gatos Research has developed a next generation mid-infrared Off-Axis Integrated Cavity Output Spectroscopy (OA-ICOS) analyzer to quantify all stable isotope ratios of N2O (δ15N, δ15Nα, δ15Nβ, δ18O, δ17O). We present the latest performance data demonstrating the precision and accuracy of the OA-ICOS based measurement. At an N2O concentration of 322 ppb, the analyzer quantifies [N2O], δ15N, δ15Na, δ15Nb, and δ18O with a precision of ±0.05 ppb, ±0.4 ‰, ±0.45 ‰, and ±0.6 ‰, and ±0.8 ‰ respectively (1σ, 100s; 1σ, 1000s for δ18O). Measurements of gas standards demonstrate accuracy better than ±1 ‰ for isotope ratios over a wide dynamic range (200 - 100,000 ppb). The measurement of δ17O requires a higher concentration (1 - 50 ppm), easily obtainable through conversion of nitrates in water. For 10 ppm of N2O, the instrument achieves a δ17O precision of ±0.05 ‰ (1σ, 1000s). This performance is sufficient to quantify atmospheric

  16. Radiogenic and stable isotopes of mid-Miocene silicic volcanism in eastern Oregon: Evidence for variable and high Sr / low δ18O domains west of the terrane-cratonic lithosphere transition

    NASA Astrophysics Data System (ADS)

    Jenkins, E. N.; Streck, M. J.; Ramos, F. C.; Bindeman, I. N.

    2013-12-01

    Widespread mid-Miocene rhyolite volcanism of eastern Oregon mostly coeval with flood basalts of the Columbia River Basalt Province allows for mapping crustal domains using radiogenic and stable isotopes. Rhyolites are thought to be derived in large part by partial melting of the crust and thus yield direct information on the composition of the crust. Silicic volcanism is expressed in the form of numerous domes and tuffs exposed over a wide area (~300 km in N-S dimension and ~100 km in E-W dimension) west of the craton boundary, which runs parallel but mostly east of the Oregon-Idaho state border as delineated by geophysical characteristics and isotopic transitions. Here, we mainly focus on initial 87Sr/86Sr ratios and δ18O obtained from mid-Miocene silicic volcanic centers in eastern Oregon. Our data, in combination with data from the literature, indicate variable 87Sr/86Sr mostly along longitudinal sections, yet more similar ratios in latitudinal directions. Except for rare examples on the west side, dispersion of 87Sr/86Sr ratios among both silicic and basaltic rocks occurs eastward of 118.6°W. For example, rhyolites in the Owyhee region between 117.10°W and 117.25°W retain 87Sr/86Sr ratios ranging from 0.70413 to 0.70566. The most radiogenic Sri ratio of 0.70787 in our study is obtained on a plagioclase separate from Buchanan Dome complex located near the western boundary of our study area. Feldspar separates and fresh groundmass of samples from adjacent centers yield similar 87Sr/86Sr ratios. δ18O values for feldspars range from below 2‰ to above 9‰. In addition, there is a crude trend of rhyolites having lower δ18O and more radiogenic 87Sr/86Sr ratios. With one exception, all samples with 87Sr/86Sr above 0.7050 are depleted in 18O18O <5.5‰), while rhyolites with 87Sr/86Sr below 0.7045 are enriched in 18O18O >6‰). The most depleted oxygen ratios (<2‰) come from rhyolites ~80 km west of the cratonic margin reflecting remelting or

  17. Determination of wine authenticity and geographical origin by measuring non-exchangeable hydrogen stable isotopes in wine ethanol with EIM-IRMS® methodology in combination with δ18O values obtained from wine water.

    NASA Astrophysics Data System (ADS)

    Smajlovic, Ivan; Glavanovic, Mirko; Sparks, Kimberlee L.; Sparks, Jed P.; Jovic, Slobodan

    2014-05-01

    Wine consumption has grown significantly in the last two decades, with the United States being the leading consumer of wine in the world. It is also the second largest wine producer and importer after the European Union, which consists of 27 European countries. The world has seen a significant increase in production from new world countries, especially the United States, Australia and Chile, and wine imports have grown significantly with this globalization. The quality and authenticity of products have become critical concerns. With the amount of wine being imported the need for verifying wine authenticity and understanding procedures used in wine making has become more important than ever. Understanding the origin of consumed wine in rapidly expanding global economy has become fundamental in order to control quality and protect consumers. In our previous scientific work we have shown that EIM-IRMS®, Ethanol Isotope Measurement - Isotope Ratio Mass Spectrometry (EIM-IRMS®), is capable of providing unique molecular fingerprint that cannot be reproduced or counterfeited. Today we know that δ18O value from the wine water is one of the most important parameters which can give information about wine geographical origin. Earlier we have suggested that grape juice or grape pulp is a closed biochemical system in which all chemical compounds stand in dynamic equilibrium and are in direct connection with each other. Taking that into consideration we have concluded that if system is genuine and if no water, or no sugar has been added to the grape must or grape juice prior to alcoholic fermentation, then ethanol which is made in process of alcoholic fermentation will have specific δD value of non-exchangeable hydrogen stable isotopes which will be in range from -205 to -215 ‰ vs. V-SMOW. In this work we will show that this value, which we named δDn (non-exchangeable hydrogen stable isotopes in ethanol), is very important because it can support or refute conclusions

  18. Latest Paleocene benthic extinction event on the southern Tethyan shelf (Egypt): Foraminiferal stable isotopic (δ13C, δ18O) records

    NASA Astrophysics Data System (ADS)

    Schmitz, B.; Speijer, R. P.; Aubry, M.-P.

    1996-04-01

    The dramatic global extinction of 35% 50% of benthic foraminifera species in the deep sea in the latest Paleocene and associated negative excursions in δ13C and δ18O may be related to spreading of warm, saline bottom water from subtropical Tethyan shallow regions over the sea floor worldwide. Our study of neritic sections in Egypt shows that in the southern shallow Tethys, a prominent long-term change in bottom-water chemistry, sedimentation, and benthic foraminifera fauna was initiated at the time when the deep-sea benthic extinction event (BEE) took place. Bottom-water δ13C values on the Tethyan shelf show a sudden 3.0‰ negative shift at this event; however, contrary to the deep sea, in which the δ13C excursion was of short duration, Tethyan δ13C values did not fully return to preboundary values, but remained depressed by ˜1.5‰ for at least 1 m.y. The δ13C values at the Egyptian shelf during the BEE are much lower than would be expected if this was a source region for global deep water. The δ18O values indicate no significant change in bottom-water salinity or temperature at the BEE. The long-lasting environmental changes that began on the Egyptian shelf at the BEE may be related to, for example, gateway reorganization along the Tethyan seaway. Paleogeographic changes possibly also triggered a change in the loci of global deep-water formation; however, these loci must be sought in another part of the Tethys.

  19. Conifers, Angiosperm Trees, and Lianas: Growth, Whole-Plant Water and Nitrogen Use Efficiency, and Stable Isotope Composition (δ13C and δ18O) of Seedlings Grown in a Tropical Environment1[W][OA

    PubMed Central

    Cernusak, Lucas A.; Winter, Klaus; Aranda, Jorge; Turner, Benjamin L.

    2008-01-01

    Seedlings of several species of gymnosperm trees, angiosperm trees, and angiosperm lianas were grown under tropical field conditions in the Republic of Panama; physiological processes controlling plant C and water fluxes were assessed across this functionally diverse range of species. Relative growth rate, r, was primarily controlled by the ratio of leaf area to plant mass, of which specific leaf area was a key component. Instantaneous photosynthesis, when expressed on a leaf-mass basis, explained 69% of variation in r (P < 0.0001, n = 94). Mean r of angiosperms was significantly higher than that of the gymnosperms; within angiosperms, mean r of lianas was higher than that of trees. Whole-plant nitrogen use efficiency was also significantly higher in angiosperm than in gymnosperm species, and was primarily controlled by the rate of photosynthesis for a given amount of leaf nitrogen. Whole-plant water use efficiency, TEc, varied significantly among species, and was primarily controlled by ci/ca, the ratio of intercellular to ambient CO2 partial pressures during photosynthesis. Instantaneous measurements of ci/ca explained 51% of variation in TEc (P < 0.0001, n = 94). Whole-plant 13C discrimination also varied significantly as a function of ci/ca (R2 = 0.57, P < 0.0001, n = 94), and was, accordingly, a good predictor of TEc. The 18O enrichment of stem dry matter was primarily controlled by the predicted 18O enrichment of evaporative sites within leaves (R2 = 0.61, P < 0.0001, n = 94), with some residual variation explained by mean transpiration rate. Measurements of carbon and oxygen stable isotope ratios could provide a useful means of parameterizing physiological models of tropical forest trees. PMID:18599645

  20. The Study of the Groundwater by Using the 34S and 18O of the Sulphates-S18O4 Isotopes

    NASA Astrophysics Data System (ADS)

    Awad, Sadek

    The stable isotope of the sulphur atom (34S) and the 18O of the sulphates (S18O4) give information about the type of the mineralisation of the groundwater existing during the water seepage. The decrease of the concentrations in dissolved SO42- (meq/L) versus the increase of δ18O (‰ vs. SMOW) of the sulphates (S18O42-) confirms a partial reduction of the dissolved sulphates in the water. The Under-saturated waters versus the gypsum do not cause the precipitations of the sulphates. The study of δ34S (‰ CD) vs. Cl- (mg/L) indicates high variations in δ34S (‰ CD) for weak difference in the Cl- (mg/L) content, this is due to the reduction of the dissolved sulphates. Concerning the Jurassic water in Lebanon, an oxidation of the sulphide can take place.

  1. Stable Isotopes18O and δ2H) Help to Delineate Flow Paths and the Importance of Different Climate Patterns in Watersheds of the Luquillo Mountains, Puerto Rico

    NASA Astrophysics Data System (ADS)

    Scholl, M. A.; Shanley, J. B.; Scatena, F. N.

    2009-12-01

    Precipitation isotopic signatures can help determine the relative importance of different rainfall regimes in the interactions between water, soils, and ecosystems in watersheds. The tropical forest in the Luquillo Mountains of Puerto Rico can receive over 5000 mm of precipitation per year. Recent modeling studies indicate that global climate change or local land use changes may lead to a decline in precipitation amounts. Weather analysis showed that 29% of rain input to the Luquillo Mountains was trade-wind orographic rainfall, and 30% of rainfall could be attributed to easterly waves and low pressure systems, with the remainder from fronts, troughs, and isolated thunderstorms. Trade-wind orographic precipitation usually occurs as frequent, low-intensity and low-volume rain events, whereas easterly waves and low-pressure systems have higher volume and more intense rainfall. To help determine the importance of different precipitation types in the forest water cycle, monthly precipitation samples from a network of rain and cloud water collectors and stream samples from two watersheds were collected and analyzed for δ18O and δ2H. Weekly throughfall and rain samples were also collected at one site during five periods of different rainfall intensity to determine whether isotopic fractionation occurs when rain falls through the forest canopy. Seasonal rainfall sources have distinct isotopic signatures, partly due to differences in cloud height associated with the seasonal climate patterns. Monthly precipitation samples during the dry season had average isotopic values of -1.5‰ δ18O and +2.3‰ δ2H, associated with the weather pattern of trade-wind showers and fronts. Rainy season precipitation, from easterly waves and low pressure systems, had average monthly values of -3.7‰ δ18O and -16‰ δ2H. Precipitation during months with significant low pressure systems had average values of -5.9‰ δ18O and -36‰ δ2H. Isotopic composition of stream water at higher

  2. δ18O water isotope in the iLOVECLIM model (version 1.0) - Part 1: Implementation and verification

    NASA Astrophysics Data System (ADS)

    Roche, D. M.

    2013-03-01

    A new 18O stable water isotope scheme is developed for three components of the iLOVECLIM coupled climate model: atmospheric, oceanic and land surface. The equations required to reproduce the fractionation of stable water isotopes in the simplified atmospheric model ECBilt are developed consistently with the moisture scheme. Simplifications in the processes are made to account for the simplified vertical structure including only one moist layer. Implementation of these equations together with a passive tracer scheme for the ocean and a equilibrium fractionation scheme for the land surface leads to the closure of the (isotopic-)water budget in our climate system. Following the implementation, verification of the existence of usual δ18O to climatic relationships are performed for the Rayleigh distillation, the Dansgaard relationship and the δ18O-salinity relationship. Advantages and caveats of the approach taken are outlined.

  3. 13C-18O isotope signatures and ‘clumped isotope’ thermometry in foraminifera and coccoliths

    NASA Astrophysics Data System (ADS)

    Tripati, Aradhna K.; Eagle, Robert A.; Thiagarajan, Nivedita; Gagnon, Alexander C.; Bauch, Henning; Halloran, Paul R.; Eiler, John M.

    2010-10-01

    Accurate constraints on past ocean temperatures and compositions are critical for documenting climate change and resolving its causes. Most proxies for temperature are not thermodynamically based, appear to be subject to biological processes, require regional calibrations, and/or are influenced by fluid composition. As a result, their interpretation becomes uncertain when they are applied in settings not necessarily resembling those in which they were empirically calibrated. Independent proxies for past temperature could provide an important means of testing and/or expanding on existing reconstructions. Here we report measurements of abundances of stable isotopologues of calcitic and aragonitic benthic and planktic foraminifera and coccoliths, relate those abundances to independently estimated growth temperatures, and discuss the possible scope of equilibrium and kinetic isotope effects. The proportions of 13C- 18O bonds in these samples exhibits a temperature dependence that is generally similar to that previously been reported for inorganic calcite and other biologically precipitated carbonate-containing minerals (apatite from fish, reptile, and mammal teeth; calcitic brachiopods and molluscs; aragonitic coral and mollusks). Most species that exhibit non-equilibrium 18O/ 16O (δ 18O) and 13C/ 12C (δ 13C) ratios are characterized by 13C- 18O bond abundances that are similar to inorganic calcite and are generally indistinguishable from apparent equilibrium, with possible exceptions among benthic foraminiferal samples from the Arctic Ocean where temperatures are near-freezing. Observed isotope ratios in biogenic carbonates can be explained if carbonate minerals generally preserve a state of ordering that reflects the extent of isotopic equilibration of the dissolved inorganic carbon species.

  4. Quantitative microbial ecology through stable isotope probing.

    PubMed

    Hungate, Bruce A; Mau, Rebecca L; Schwartz, Egbert; Caporaso, J Gregory; Dijkstra, Paul; van Gestel, Natasja; Koch, Benjamin J; Liu, Cindy M; McHugh, Theresa A; Marks, Jane C; Morrissey, Ember M; Price, Lance B

    2015-11-01

    Bacteria 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 to stable isotope probing (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 in (18)O and (13)C composition after exposure to [(18)O]water or [(13)C]glucose. The addition of glucose increased the assimilation of (18)O into DNA from [(18)O]water. However, the increase in (18)O 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.

  5. Stable isotope studies

    SciTech Connect

    Ishida, T.

    1992-01-01

    The research has been in four general areas: (1) correlation of isotope effects with molecular forces and molecular structures, (2) correlation of zero-point energy and its isotope effects with molecular structure and molecular forces, (3) vapor pressure isotope effects, and (4) fractionation of stable isotopes. 73 refs, 38 figs, 29 tabs.

  6. Vehicle emissions of greenhouse gases and related tracers from a tunnel study: CO : CO2, N2O : CO2, CH4 : CO2, O2 : CO2 ratios, and the stable isotopes 13C and 18O in CO2 and CO

    NASA Astrophysics Data System (ADS)

    Popa, M. E.; Vollmer, M. K.; Jordan, A.; Brand, W. A.; Pathirana, S. L.; Rothe, M.; Röckmann, T.

    2014-02-01

    Measurements of CO2, CO, N2O and CH4 mole fractions, O2 / N2 ratios and the stable isotopes 13C and 18O in CO2 and CO have been performed in air samples from the Islisberg highway tunnel (Switzerland). The molar CO : CO2 ratios, with an average of (4.15 ± 0.34) ppb:ppm, are lower than reported in previous studies, pointing to a reduction in CO emissions from traffic. The 13C in CO2 reflects the isotopic composition of the fuel. 18O in CO2 is slightly depleted compared to the 18O in atmospheric O2, and shows significant variability. In contrast, the δ13C values of CO show that significant fractionation takes place during CO destruction in the catalytic converter. 13C in CO is enriched by 3‰ compared to the 13C in the fuel burnt, while the 18O content is similar to that of atmospheric O2. We compute a fractionation constant of (-2.7 ± 0.7)‰ for 13C during CO destruction. The N2O : CO2 average ratio of (1.8 ± 0.2) × 10-2 ppb:ppm is significantly lower than in past studies, showing a reduction in N2O emissions likely related to improvements in the catalytic converter technology. We also observed small CH4 emissions, with an average CH4 : CO2 ratio of (4.6 ± 0.2) × 10-2 ppb:ppm. The O2 : CO2 ratios of (-1.47 ± 0.01) ppm:ppm are very close to the expected, theoretically calculated values of O2 depletion per CO2 enhancement.

  7. Compound specific 13C- and 18O-isotope analysis of organic aerosols

    NASA Astrophysics Data System (ADS)

    Blees, Jan; Saurer, Matthias; Siegwolf, Rolf T. W.; Dommen, Josef; Baltensperger, Urs

    2014-05-01

    . Elements other than carbon may provide valuable additional information. Here we report on the development of methods for the analysis of stable carbon and oxygen isotope ratios of organic compounds in aerosols, through GC-combustion-irMS and GC-pyrolysis-irMS. We apply these analyses to environmental aerosol samples and samples of smog-chamber experiments, with the aim of identifying isotopic signatures of sources and pathways. We will pay special attention to derivatisation techniques - notably alternatives to the often-used trimethylsilyl derivatives in GC-pyrolysis-irMS for δ18O analysis - and to compound separation and identification. We present initial data of combined δ13C and δ18O studies on (secondary) organic aerosol samples, and their added value for source apportionment studies.

  8. δ18O water isotope in the iLOVECLIM model (version 1.0) - Part 1: Implementation and verification

    NASA Astrophysics Data System (ADS)

    Roche, D. M.

    2013-09-01

    A new 18O stable water isotope scheme is developed for three components of the iLOVECLIM coupled climate model: atmospheric, oceanic and land surface. The equations required to reproduce the fractionation of stable water isotopes in the simplified atmospheric model ECBilt are developed consistently with the moisture scheme. Simplifications in the processes are made to account for the simplified vertical structure including only one moist layer. Implementation of these equations together with a passive tracer scheme for the ocean and a equilibrium fractionation scheme for the land surface leads to the closure of the (isotopic-) water budget in our climate system. Following the implementation, verification of the existence of usual δ18O to climatic relationships are performed for the Rayleigh distillation, the Dansgaard relationship and the δ18O -salinity relationship. Advantages and caveats of the approach taken are outlined. The isotopic fields simulated are shown to reproduce most expected oxygen-18-climate relationships with the notable exception of the isotopic composition in Antarctica.

  9. Investigation of spatio-temporal variability of water uptake in a groundwater-dependent ecosystem using a stable isotope approach (δ18O, δ2H): Pfyn Forest, Switzerland

    NASA Astrophysics Data System (ADS)

    Bertrand, G.; Masini, J.; Goldscheider, N.; Gobat, J. M.; Hunkeler, D.

    2012-04-01

    This work consists of an eco-hydrogeological study of the Pfyn Forest (46o17'35''N; 7o31'59''E, z = 550 m) which is a 6 km long alluvial zone in the upper Rhône valley, near Sierre (Wallis, Switzerland). From a hydrological point of view, the Rhône has a glacio-nival regime type in this area. Between low-flow and high-flow periods, groundwater levels strongly vary (about 8 m) near the main river-aquifer interaction zone in the most upgradient part of the site. In contrast, the downstream part of Pfyn is characterized by a low groundwater level fluctuation of about 1 or 2 m. From an ecological point of view, the riverine fringe at Pfyn presents a broadly recognized natural value but faces many threats due to human activities (derivation channel located upstream, gravel pits). Phytocoenosis vary from dry environments associations (with Scots pines, feather grass) upstream to active floodplain associations (with poplars, alders, willows) and likely dependent on groundwater, downstream. Between these two end-members, a transition mixed forest occurs. In the context of a potential hydrologic alteration due to global climatic change in a close future, this ecosystem should face modifications of the various water source (rainwater, groundwater) proportion and availability. In order to constrain the meteorological, hydrological, pedological and ecological factors governing water uptakes by trees, isotopic characterizations (δ18O, δ2H) of each water compartment (precipitations, groundwater, river, soil, xylem) coupled with the evaluation of the water balance, has been carried out. The investigation focused on 3 different sites located along a transect through the alluvial valley between April 2010 and February 2011, with a twice-monthly resolution. The data permit to obtain three major findings: - At first, an overview of both δ18O and δ2H data shows that rainwater, groundwater, soil water and plant water are usually located on the regional meteoric water line. For

  10. Isotopic Water Analyzer for Highly Precise Measurements of δ2H, δ18O, and δ17O

    NASA Astrophysics Data System (ADS)

    Berman, E. S.; Fortson, S.; Snaith, S.; Gupta, M.

    2012-12-01

    Measurements of the stable isotope ratios (δ2H, δ18O and δ17O) of both liquid water and water vapor are widely used in hydrology, atmospheric sciences, and biogeochemistry to determine the migration of water through an ecosystem. Previously, discrete samples were collected (or condensed) and transported to an isotope ratio mass spectrometer for characterization. Due to the expense and labor associated with such sampling, isotope studies were generally limited in scope and in temporal resolution. We report on the continued development of a field-portable Isotopic Water Analyzer that exploits cavity-enhanced absorption spectrometry (e.g. Off-Axis ICOS) to accurately and rapidly quantify δ2H, δ18O and δ17O of both liquid water and water vapor. The instrument is thermally-controlled to better than ±8 mK and is capable of measuring over 90 liquid samples/day with δ2H, δ18O and δ17O precisions exceeding ±0.2 ‰, ±0.05 ‰, and ±0.06 ‰ respectively. Subsequent averaging yields δ2H, δ18O and δ17O precisions exceeding ±0.077 ‰, ±0.023 ‰, and ±0.03 ‰ respectively with over 22 samples/day. The accuracy of the liquid analyzer was confirmed over a very wide dynamic range (δ2H = -455 to +671 ‰ with comparable δ18O and δ17O values) by direct comparison to isotope ratio mass spectrometry. Moreover, the ability to directly measure 17O-excess, vapor samples, and unnatural waters (e.g. plant water, soil water, urine, blood, saliva…) will also be presented.

  11. Dentine oxygen isotopes (δ (18)O) as a proxy for odontocete distributions and movements.

    PubMed

    Matthews, Cory J D; Longstaffe, Fred J; Ferguson, Steven H

    2016-07-01

    Spatial variation in marine oxygen isotope ratios (δ (18)O) resulting from differential evaporation rates and precipitation inputs is potentially useful for characterizing marine mammal distributions and tracking movements across δ (18)O gradients. Dentine hydroxyapatite contains carbonate and phosphate that precipitate in oxygen isotopic equilibrium with body water, which in odontocetes closely tracks the isotopic composition of ambient water. To test whether dentine oxygen isotope composition reliably records that of ambient water and can therefore serve as a proxy for odontocete distribution and movement patterns, we measured δ (18)O values of dentine structural carbonate (δ (18) OSC) and phosphate (δ (18) OP) of seven odontocete species (n = 55 individuals) from regional marine water bodies spanning a surface water δ (18)O range of several per mil. Mean dentine δ (18) OSC (range +21.2 to +25.5‰ VSMOW) and δ (18) OP (+16.7 to +20.3‰) values were strongly correlated with marine surface water δ (18)O values, with lower dentine δ (18) OSC and δ (18) OP values in high-latitude regions (Arctic and Eastern North Pacific) and higher values in the Gulf of California, Gulf of Mexico, and Mediterranean Sea. Correlations between dentine δ (18) OSC and δ (18) OP values with marine surface water δ (18)O values indicate that sequential δ (18)O measurements along dentine, which grows incrementally and archives intra- and interannual isotopic composition over the lifetime of the animal, would be useful for characterizing residency within and movements among water bodies with strong δ (18)O gradients, particularly between polar and lower latitudes, or between oceans and marginal basins. PMID:27547302

  12. Dentine oxygen isotopes (δ (18)O) as a proxy for odontocete distributions and movements.

    PubMed

    Matthews, Cory J D; Longstaffe, Fred J; Ferguson, Steven H

    2016-07-01

    Spatial variation in marine oxygen isotope ratios (δ (18)O) resulting from differential evaporation rates and precipitation inputs is potentially useful for characterizing marine mammal distributions and tracking movements across δ (18)O gradients. Dentine hydroxyapatite contains carbonate and phosphate that precipitate in oxygen isotopic equilibrium with body water, which in odontocetes closely tracks the isotopic composition of ambient water. To test whether dentine oxygen isotope composition reliably records that of ambient water and can therefore serve as a proxy for odontocete distribution and movement patterns, we measured δ (18)O values of dentine structural carbonate (δ (18) OSC) and phosphate (δ (18) OP) of seven odontocete species (n = 55 individuals) from regional marine water bodies spanning a surface water δ (18)O range of several per mil. Mean dentine δ (18) OSC (range +21.2 to +25.5‰ VSMOW) and δ (18) OP (+16.7 to +20.3‰) values were strongly correlated with marine surface water δ (18)O values, with lower dentine δ (18) OSC and δ (18) OP values in high-latitude regions (Arctic and Eastern North Pacific) and higher values in the Gulf of California, Gulf of Mexico, and Mediterranean Sea. Correlations between dentine δ (18) OSC and δ (18) OP values with marine surface water δ (18)O values indicate that sequential δ (18)O measurements along dentine, which grows incrementally and archives intra- and interannual isotopic composition over the lifetime of the animal, would be useful for characterizing residency within and movements among water bodies with strong δ (18)O gradients, particularly between polar and lower latitudes, or between oceans and marginal basins.

  13. Stable-Isotopic Analysis of Porcine, Bovine, and Ovine Heparins

    PubMed Central

    Jasper, John P.; Zhang, Fuming; Poe, Russell B.; Linhardt, Robert J.

    2014-01-01

    The assessment of provenance of heparin is becoming a major concern for the pharmaceutical industry and its regulatory bodies. Batch-specific [carbon (δ13C), nitrogen (δ15N), oxygen (δ18O), sulfur (δ34S), and hydrogen (δD)] stable-isotopic compositions of five different animal-derived heparins were performed. Measurements readily allowed their differentiation into groups and/or subgroups based on their isotopic provenance. Principle component analysis showed that a bivariate plot of δ13C and δ18O is the best single, bivariate plot that results in the maximum discrimination ability when only two stable isotopes are used to describe the variation in the data set. Stable-isotopic analyses revealed that (i) stable-isotope measurements on these highly-sulfated polysaccharide (MW ~15 kDa) natural products (“biologics”) were feasible; (ii) in bivariate plots, the δ13C versus δ18O plot reveals a well-defined relationship for source differentiation of hogs raised in the US from hogs raised in Europe and China; (iii) the δD versus δ18O plot revealed the most well-defined relationship for source differentiation based on the hydrologic-environmental isotopes of water (D/H and 18O/16O), and (iv) the δ15N versus δ18O and δ34S versus δ18O relationships are both very similar, possibly reflecting the food sources used by the different heparin producers. PMID:25186630

  14. Stable isotopic analysis of porcine, bovine, and ovine heparins.

    PubMed

    Jasper, John P; Zhang, Fuming; Poe, Russell B; Linhardt, Robert J

    2015-02-01

    The assessment of provenance of heparin is becoming a major concern for the pharmaceutical industry and its regulatory bodies. Batch-specific [carbon (δ(13) C), nitrogen (δ(15) N), oxygen (δ(18) O), sulfur (δ(34) S), and hydrogen (δD)] stable isotopic compositions of five different animal-derived heparins were performed. Measurements readily allowed their differentiation into groups and/or subgroups based on their isotopic provenance. Principle component analysis showed that a bivariate plot of δ(13) C and δ(18) O is the best single, bivariate plot that results in the maximum discrimination ability when only two stable isotopes are used to describe the variation in the data set. Stable isotopic analyses revealed that (1) stable isotope measurements on these highly sulfated polysaccharide (molecular weight ∼15 kDa) natural products ("biologics") were feasible; (2) in bivariate plots, the δ(13) C versus δ(18) O plot reveals a well-defined relationship for source differentiation of hogs raised in the United States from hogs raised in Europe and China; (3) the δD versus δ(18) O plot revealed the most well-defined relationship for source differentiation based on the hydrologic environmental isotopes of water (D/H and (18) O/(16) O); and (4) the δ(15) N versus δ(18) O and δ(34) S versus δ(18) O relationships are both very similar, possibly reflecting the food sources used by the different heparin producers. PMID:25186630

  15. Stable isotopic analysis of porcine, bovine, and ovine heparins.

    PubMed

    Jasper, John P; Zhang, Fuming; Poe, Russell B; Linhardt, Robert J

    2015-02-01

    The assessment of provenance of heparin is becoming a major concern for the pharmaceutical industry and its regulatory bodies. Batch-specific [carbon (δ(13) C), nitrogen (δ(15) N), oxygen (δ(18) O), sulfur (δ(34) S), and hydrogen (δD)] stable isotopic compositions of five different animal-derived heparins were performed. Measurements readily allowed their differentiation into groups and/or subgroups based on their isotopic provenance. Principle component analysis showed that a bivariate plot of δ(13) C and δ(18) O is the best single, bivariate plot that results in the maximum discrimination ability when only two stable isotopes are used to describe the variation in the data set. Stable isotopic analyses revealed that (1) stable isotope measurements on these highly sulfated polysaccharide (molecular weight ∼15 kDa) natural products ("biologics") were feasible; (2) in bivariate plots, the δ(13) C versus δ(18) O plot reveals a well-defined relationship for source differentiation of hogs raised in the United States from hogs raised in Europe and China; (3) the δD versus δ(18) O plot revealed the most well-defined relationship for source differentiation based on the hydrologic environmental isotopes of water (D/H and (18) O/(16) O); and (4) the δ(15) N versus δ(18) O and δ(34) S versus δ(18) O relationships are both very similar, possibly reflecting the food sources used by the different heparin producers.

  16. Multi-isotope labelling (13C, 18O, 2H) for studying organic matter cycling within plant-soil systems

    NASA Astrophysics Data System (ADS)

    Studer, M. S.; Abiven, S.; Schmidt, M. W. I.; Siegwolf, R. T. W.

    2012-04-01

    Carbon cycling has become of major interest for the understanding and mitigation of global climatic change. Terrestrial ecosystems have a large carbon sequestration potential, but many processes and fluxes of organic matter (OM) cycling within the plant-soil system are not yet well understood [1]. The dynamics of OM cycling within the plant soil-system are determined by environmental parameters, as well as chemical quality of OM input. A well-known technique to study OM dynamics is to label OM inputs with stable isotopes (e.g 13C). Changes in OM quality in the plant and in the soil can be assessed by compound specific isotopic analysis [2]. These techniques give a precise insight of the OM composition, but are laborious and expensive. Here we suggest a new multi-isotope labelling technique using stable 13C in combination with stable 18O and 2H isotopes, which provides information on OM quality by simple bulk material analysis. The method is based on the creation of an isotopic van Krevelen diagram, which is used to describe different compound groups by plotting the atomic ratios of O/C vs. H/C [3]. We could show that new assimilates can be labelled with 13C, 18O and 2H by adding the stable isotopes (continuously) in the gaseous phase (CO2 and water vapour) to the plants atmosphere. The label has been traced within the bulk material of different compartments of the plant-soil system (e.g. leaves, stems, roots, bulk soil). Our first results showed that after 2, 8 and 14 days of labelling the 18O/13C(new) ratio was notably different in leaf, stem and root tissue (0.0024, 0.0011 and 0.0007, respectively), suggesting a change in OM quality towards more C-rich compounds. d2H analysis will follow and an isotopic van Krevelen diagram will be produced (18O/13C(new) vs. 2H/13C(new)) to describe the changes in OM quality. The new multi-isotope labelling approach represent a powerful tool to address open questions in plant and soil research such as the allocation of organic

  17. A novel methodological approach for δ(18)O analysis of sugars using gas chromatography-pyrolysis-isotope ratio mass spectrometry.

    PubMed

    Zech, Michael; Saurer, Matthias; Tuthorn, Mario; Rinne, Katja; Werner, Roland A; Siegwolf, Rolf; Glaser, Bruno; Juchelka, Dieter

    2013-01-01

    Although the instrumental coupling of gas chromatography-pyrolysis-isotope ratio mass spectrometry (GC-Py-IRMS) for compound-specific δ(18)O analysis has been commercially available for more than a decade, this method has been hardly applied so far. Here we present the first GC-Py-IRMS δ(18)O results for trimethylsilyl-derivatives of plant sap-relevant sugars and a polyalcohol (glucose, fructose, sucrose, raffinose and pinitol). Particularly, we focus on sucrose, which is assimilated in leaves and which is the most important transport sugar in plants and hence of utmost relevance in plant physiology and paleoclimate studies. Replication measurements of sucrose standards and concentration series indicate that the GC-Py-IRMS δ(18)O measurements are not stable over time and that they are amount (area) dependent. We, therefore, suggest running sample batch replication measurements in alternation with standard concentration series of reference material. This allows for carrying out (i) a drift correction, (ii) a calibration against reference material and (iii) an amount (area) correction. Tests with (18)O-enriched water do not provide any evidence for oxygen isotope exchange reactions affecting sucrose and raffinose. We present the first application of GC-Py-IRMS δ(18)O analysis for sucrose from needle extract (soluble carbohydrate) samples. The obtained δ(18)Osucrose/ Vienna Standard Mean Ocean Water (VSMOW) values are more positive and vary in a wider range (32.1-40.1 ‰) than the δ(18)Obulk/ VSMOW values (24.6-27.2 ‰). Furthermore, they are shown to depend on the climate parameters maximum day temperature, relative air humidity and cloud cover. These findings suggest that δ(18)Osucrose of the investigated needles very sensitively reflects the climatically controlled evaporative (18)O enrichment of leaf water and thus highlights the great potential of GC-Py-IRMS δ(18)Osucrose analysis for plant physiology and paleoclimate studies. PMID:24313371

  18. sup 13 C and sup 18 O isotopic disequilibrium in biological carbonates: I. Patterns

    SciTech Connect

    McConnaughey, T. )

    1989-01-01

    Biological carbonates frequently precipitate out of {sup 18}O and {sup 13}C equilibrium with ambient waters. Two patterns of isotopic disequilibrium are particularly common. Kinetic disequilibria, so designated because they apparently result from kinetic isotope effects during CO{sub 2} hydration and hydroxylation, involve simultaneous depletions of {sup 18}O and {sup 13}C as large as 4{per thousand} and 10 to 15{per thousand}, respectively. Rapid skeletogenesis favors strong kinetic effects, and approximately linear correlations between skeletal {delta}{sup 18}O and {delta}{sup 13}C are common in carbonates showing mainly the kinetic pattern. Metabolic effects involve additional positive or negative modulation of skeletal {delta}{sup 13}C, reflecting changes in the {delta}{sup 13}C of dissolved inorganic carbon, caused mainly by photosynthesis and respiration. Kinetic isotope disequilibria tend to be fairly consistent in rapidly growing parts of photosynthetic corals, and time dependent isotopic variations therefore reflect changes in environmental conditions. {delta}{sup 18}O variations from Galapagos corals yields meaningful clues regarding seawater temperature, while {delta}{sup 13}C variations reflect changes in photosynthesis, modulated by cloudiness.

  19. Stable isotopes in mineralogy

    USGS Publications Warehouse

    O'Neil, J.R.

    1977-01-01

    Stable isotope fractionations between minerals are functions of the fundamental vibrational frequencies of the minerals and therefore bear on several topics of mineralogical interest. Isotopic compositions of the elements H, C, O, Si, and S can now be determined routinely in almost any mineral. A summary has been made of both published and new results of laboratory investigations, analyses of natural materials, and theoretical considerations which bear on the importance of temperature, pressure, chemical composition and crystal structure to the isotopic properties of minerals. It is shown that stable isotope studies can sometimes provide evidence for elucidating details of crystal structure and can be a powerful tool for use in tracing the reaction paths of mineralogical reactions. ?? 1977 Springer-Verlag.

  20. A Method to Determine 18O Kinetic Isotope Effects in the Hydrolysis of Nucleotide Triphosphates

    PubMed Central

    Du, Xinlin; Ferguson, Kurt; Sprang, Stephen R.

    2007-01-01

    A method to determine 18O kinetic isotope effects (KIE) in the hydrolysis of GTP is described that is generally applicable to reactions involving other nucleotide triphosphates. Internal competition, wherein the substrate of the reaction is a mixture of 18O-labeled and unlabeled nucleotides, is employed and the change in relative abundance of the two species in the course of the reaction is used to calculate KIE. The nucleotide labeled with 18O at sites of mechanistic interest also contains 13C at all carbon positions, while the 16O-nucleotide is depleted of 13C. The relative abundance of the labeled and unlabeled substrates or products is reflected in the carbon isotope ratio (13C/12C) in GTP or GDP, which is determined by use of a liquid chromatography-coupled isotope ratio mass spectrometer (LC-coupled IRMS). The LC is coupled to the IRMS by an Isolink™ interface (ThermoFinnigan). Carbon isotope ratios can be determined with accuracy and precision greater than 0.04%, and are consistent over an order of magnitude in sample amount. KIE values for Ras/NF1333-catalyzed hydrolysis of [β18O3,13C]GTP were determined by change in the isotope ratio of GTP or GDP or the ratio of the isotope ratio of GDP to that of GTP. KIE values computed in the three ways agree within 0.1%, although the method using the ratio of isotope ratios of GDP and GTP gives superior precision (< 0.1%). A single KIE measurement can be conducted in 25 minutes with less than 5 μg nucleotide reaction product. PMID:17963711

  1. A Climate Driven Speleothem Stable Isotope Model

    NASA Astrophysics Data System (ADS)

    Shorey, C. V.; Gonzalez, L. A.

    2004-12-01

    We have constructed a climate driven stalagmite growth model that faithfully reproduces the major annual growth trends of temperate climate stalagmites. Model results indicate that speleothem growth rate in temperate regions, although depending primarily on precipitation amount, is a complex function of the timing of precipitation relative to seasonal temperature changes as well as other non-climatic parameters. We have incorporated into this climate driven growth model the capability to simulate climate driven carbon and oxygen stable isotope changes and their incorporation in speleothem calcite. The model allows us to investigate the relationship between isotopic changes in soil CO2 and seepage fluids, and the isotopic composition of the growing stalagmite. We also explore the impact of sampling resolution on the extracted speleothem isotope record. We calibrated the model to replicate the growth and isotopic record of a stalagmite collected in 1982 from Mystery Cave State Park, in Southeastern Minnesota and using temperature and precipitation records spanning 1935-1982 from a nearby weather station. The model generally replicates the \\delta13C and \\delta18O record for this case. Model ouput indicates that that large deviations of temperature or precipitation from average conditions in a single year can be recorded in speleothems. Increases in temperature have a clear postive correlation with \\delta13C values, and a less direct negative correlation with \\delta18O values. Increases in precipitation have an inconsistent positive correlation with \\delta13C values and a clear positive correlation with \\delta18O values.

  2. Stable isotopic characterization of active pharmaceutical ingredients.

    PubMed

    Jasper, J P; Westenberger, B J; Spencer, J A; Buhse, L F; Nasr, M

    2004-04-01

    Stable isotopic characterization or "fingerprinting" of active pharmaceutical ingredients (APIs) is a highly-specific means of defining the provenance of these pharmaceutical materials. The isotopic analysts in this study were provided with 20 blind samples of four APIs (tropicamide, hydrocortisone, quinine HCL, and tryptophan) from one-to-five production batch(es) from one-to-five manufacturer(s). Only the chemical identity of the APIs was initially provided to the isotopic analysts. Depending on the API chemical composition, isotopic ratios of either three or four elements (13C/12C, 15N/14N, 18O/16O, and/or D/H) were measured by either elemental analyzer/isotope ratio mass spectrometry (EA/IRMS: carbon (delta13C) and nitrogen (delta15N)) or by thermal conversion-EA/IRMS (TCEA/IRMS; hydrogen (deltaD) and oxygen (delta15N)); in all cases, the isotopic results are reported in the standard delta-notation which represents part-per-thousand () variations from the isotopic ratios of international standards. The stable isotopic analyses of the four suites of APIs spanned broad ranges in absolute value (deltadelta) and in estimated specificity (a product of dynamic ranges (DR, unitless)--note that these are upper limits of specificity because some of these isotope values may be partially interdependent). The five samples of tropicamide from one production batch and one manufacturer demonstrated the narrowest ranges (deltadelta13C=0.13 ; deltadelta15N=0.52 ; deltadelta18O=0.24 ; deltadeltaD=2.8 ) and the smallest specificity of 1:30.9. By contrast, the five samples of tryptophan that came from five separate manufacturers had some of the widest isotopic ranges observed (deltadelta13C=21.32 ; deltadelta15N=5.26 ; deltadelta18O=22.07 ; deltadeltaD=55.3 ) and had the largest specificity of 1:19.6 x 10(6). The isotopic provenance of the four suites of APIs readily emerged from bivariate plots of selected isotope ratios, particularly deltaD versus delta18O.

  3. Seawater intrusion into groundwater aquifer through a coastal lake - complex interaction characterised by water isotopes (2)H and (18)O.

    PubMed

    Gemitzi, Alexandra; Stefanopoulos, Kyriakos; Schmidt, Marie; Richnow, Hans H

    2014-01-01

    The present study investigates the complex interactions among surface waters, groundwaters and a coastal lake in northeastern Greece, using their stable isotopic composition (δ(18)O, δ(2)H) in combination with hydrogeological and hydrochemical data. Seasonal and spatial trends of water isotopes were studied and revealed that all water bodies in the study area interact. It was also shown that the aquifer's increased salinity is not due to fossil water from past geological periods, but is attributed to brackish lake water intrusion into the aquifer induced by the extensive groundwater pumping for irrigation purposes. Quantification of the contribution of the lake to the aquifer was achieved using the simple dilution formula. The isotopic signatures of the seawater and the groundwaters are considerably different, so there is a very little possibility of direct seawater intrusion into the aquifer.

  4. Conditional flux analysis and stable isotopes

    NASA Astrophysics Data System (ADS)

    Zeeman, M. J.; Knohl, A.; Sturm, P.; Buchmann, N. C.; Thomas, C. K.

    2009-12-01

    We propose to investigate to what extend conditional flux analysis can benefit from the addition of stable isotope information. Stable isotopes have been recognized for their potential as process tracer, and could add an extra dimension to the conditional flux concept, which aims at directly quantifying component fluxes and identifying their sources. Differences in 13C abundance in carbon dioxide can be used to distinguish assimilation or respiration sources, whereas the 18O abundance expresses differences in water exchange, for instance between canopy and soil. Lending to recent advances in measurement technology, stable isotopes can now be measured at high temporal resolutions (10Hz) required for commonly applied micrometeorological methods such as the eddy-covariance technique, or related conditional flux methods. We will present current ideas on how the conditional flux method, as recently proposed and evaluated by Thomas et al. (2008), Scanlon & Sahu (2008), to perform daytime flux partitioning at the ecosystem level, can be refined by stable isotope analysis (13C and 18O) of carbon dioxide as additional dimension for identification of fluxes.

  5. Forensic Stable Isotope Biogeochemistry

    NASA Astrophysics Data System (ADS)

    Cerling, Thure E.; Barnette, Janet E.; Bowen, Gabriel J.; Chesson, Lesley A.; Ehleringer, James R.; Remien, Christopher H.; Shea, Patrick; Tipple, Brett J.; West, Jason B.

    2016-06-01

    Stable isotopes are being used for forensic science studies, with applications to both natural and manufactured products. In this review we discuss how scientific evidence can be used in the legal context and where the scientific progress of hypothesis revisions can be in tension with the legal expectations of widely used methods for measurements. Although this review is written in the context of US law, many of the considerations of scientific reproducibility and acceptance of relevant scientific data span other legal systems that might apply different legal principles and therefore reach different conclusions. Stable isotopes are used in legal situations for comparing samples for authenticity or evidentiary considerations, in understanding trade patterns of illegal materials, and in understanding the origins of unknown decedents. Isotope evidence is particularly useful when considered in the broad framework of physiochemical processes and in recognizing regional to global patterns found in many materials, including foods and food products, drugs, and humans. Stable isotopes considered in the larger spatial context add an important dimension to forensic science.

  6. Separating soil and leaf water 18O isotopic signals in plant stem cellulose

    NASA Astrophysics Data System (ADS)

    Sternberg, Leonel da Silveira Lobo; Anderson, William T.; Morrison, Kanema

    2003-07-01

    The oxygen-18 signal of soil and leaf water are both recorded in heterotrophically synthesized plant stem cellulose. Presently, these signals can only be teased apart with modeling and assumptions on the nature of the isotopic enrichment of leaf water. A method by which these two signals are chemically separated and analyzed is tested here. Heterotrophically synthesized cellulose from germinating seeds having a mixture of isotopic signals from the reserve carbohydrate (starch) and that of the water during cellulose synthesis was hydrolyzed and the resulting glucose converted to glucose phenylosazone. The analysis of the 18O/ 16O ratios of cellulose and of glucose phenylosazone were used to calculate the oxygen isotope ratio of the oxygen attached to the second carbon of the glucose moieties of the cellulose molecule. The calculated δ 18O value of this oxygen was highly correlated with that of the water available for cellulose synthesis showing a nearly one-to-one relationship (slope = 1.027) and leading to the conclusion that it completely exchanges with water during heterotrophic cellulose synthesis. Once this method is refined so as to increase precision, it will be possible to derive the δ 18O values of soil water available to plants from the oxygen isotope analysis of stem cellulose and its derivative.

  7. Using environmental isotopes 2H and 18O for identification of infiltration processes in floodplain ecosystems of the River Elbe.

    PubMed

    Böhnke, R; Geyer, S; Kowski, P

    2002-03-01

    We examined a floodplain area in the middle section of the river Elbe Valley with regard to hydrogeological and hydrological processes using isotopic methods. Over two years, river water and groundwater have been analysed for temporal and spatial chemical and isotopic (delta2H and delta18O) changes. By these methods we assessed the flow dynamics of the river-groundwater infiltration system. At low and mean river stages there is a general hydraulic gradient from the higher areas at the margin of the valley towards the floodplain. During floods river water infiltrates into the adjacent aquifer not primarily through the river banks but first through surface water inflow from north to south, via depressions and gullies from the back of the floodplain. The early stage of river water infiltration is characterized by a sharp decrease in conductivity and in concentrations of SO4(2-) and Cl- in the hydraulically connected shallow aquifer. delta2H and delta18O values show a similar tendency. We observed a significant minimum in stable isotope ratios during the flood in March 1999. Using a simple mixing equation it was calculated that the groundwater in the upper, shallow aquifer consists of around 70% river water in the transition zone (well 13) during flooding.

  8. ISOTOPIC RATIOS OF {sup 18}O/{sup 17}O IN THE GALACTIC CENTRAL REGION

    SciTech Connect

    Zhang, J. S.; Sun, L. L.; Riquelme, D.; Henkel, C.; Lu, D. R.; Zhang, Y.; Wang, J. Z.; Li, J.; Wang, M.

    2015-08-15

    The {sup 18}O/{sup 17}O isotopic ratio of oxygen is a crucial measure of the secular enrichment of the interstellar medium by ejecta from high-mass versus intermediate-mass stars. So far, however, there is a lack of data, particularly from the Galactic center (GC) region. Therefore, we have mapped typical molecular clouds in this region in the J = 1–0 lines of C{sup 18}O and C{sup 17}O with the Delingha 13.7 m telescope (DLH). Complementary pointed observations toward selected positions throughout the GC region were obtained with the IRAM 30 m and Mopra 22 m telescopes. C{sup 18}O/C{sup 17}O abundance ratios reflecting the {sup 18}O/{sup 17}O isotope ratios were obtained from integrated intensity ratios of C{sup 18}O and C{sup 17}O. For the first time, C{sup 18}O/C{sup 17}O abundance ratios are determined for Sgr C (V ∼ −58 km s{sup −1}), Sgr D (V ∼ 80 km s{sup −1}), and the 1.°3 complex (V ∼ 80 km s{sup −1}). Through our mapping observations, abundance ratios are also obtained for Sgr A (∼0 and ∼50 km s{sup −1} component) and Sgr B2 (∼60 km s{sup −1}), which are consistent with the results from previous single-point observations. Our frequency-corrected abundance ratios of the GC clouds range from 2.58 ± 0.07 (Sgr D, V ∼ 80 km s{sup −1}, DLH) to 3.54 ± 0.12 (Sgr A, ∼50 km s{sup −1}). In addition, strong narrow components (line width less than 5 km s{sup −1}) from the foreground clouds are detected toward Sgr D (−18 km s{sup −1}), the 1.°3 complex (−18 km s{sup −1}), and M+5.3−0.3 (22 km s{sup −1}), with a larger abundance ratio around 4.0. Our results show a clear trend of lower C{sup 18}O/C{sup 17}O abundance ratios toward the GC region relative to molecular clouds in the Galactic disk. Furthermore, even inside the GC region, ratios appear not to be uniform. The low GC values are consistent with an inside-out formation scenario for our Galaxy.

  9. Tracing atmospheric moisture from precipitation δ18O to climate proxy using an isotope enabled land surface model

    NASA Astrophysics Data System (ADS)

    Kanner, L.; Buenning, N. H.; Stott, L. D.; Timmermann, A.

    2013-12-01

    A paleoclimate interpretation of a terrestrial hydrologic proxy such as the δ18O of tree cellulose or speleothem calcite may be biased or misinterpreted if the isotopic composition of the soil water from which the proxy originated undergoes isotopic exchange or fractionation. In this study, we use a global isotope-enabled land surface model (IsoLSM) to investigate how the δ18O of precipitation may be altered in a soil column due to evaporation and vertical moisture flux. In order to assess how precipitation and evaporation contribute the soil water isotopic variability, we compare seasonal and interannual changes in simulated xylem water δ18O within a control simulation and in a suite of experiments where the effect of precipitation δ18O, water vapor δ18O, and ground water evaporation are independently removed. The simulations, carried out for 1979 to 2004, reveal that in semi-arid regions, such as the southwest United States, the seasonal cycle in xylem water δ18O is strongly affected by evaporative loss during the dry season and this can constitute as much as 50% of the interannual δ18O variance. Additional simulations, including soil water tagging experiments, indicate that upward fluxes of soil water occur during drier periods. For soil water δ18O profiles that are isotopically more depleted in 18O at depth, this imparts a low isotopic signature to xylem water δ18O during such dry intervals. Hence, without taking into account moisture flux processes, an isotopic proxy could be misinterpreted as wet conditions (due to decreased evaporative enrichment) for low δ18O years when instead drier conditions are equally as likely. Using IsoLSM simulated xylem water and leaf water δ18O, offline calculations of cellulose δ18O compare well with observations in diverse climatic regimes. Thus, the driving mechanisms on soil water δ18O identified in this study, and in particular the important role of evaporation on seasonal and interannual timescales, may

  10. Carbonate clumped isotope constraints on Silurian ocean temperature and seawater δ18O

    NASA Astrophysics Data System (ADS)

    Cummins, Renata C.; Finnegan, Seth; Fike, David A.; Eiler, John M.; Fischer, Woodward W.

    2014-09-01

    Much of what we know about the history of Earth’s climate derives from the chemistry of carbonate minerals in the sedimentary record. The oxygen isotopic compositions (δ18O) of calcitic marine fossils and cements have been widely used as a proxy for past seawater temperatures, but application of this proxy to deep geologic time is complicated by diagenetic alteration and uncertainties in the δ18O of seawater in the past. Carbonate clumped isotope thermometry provides an independent estimate of the temperature of the water from which a calcite phase precipitated, and allows direct calculation of the δ18O of the water. The clumped isotope composition of calcites is also highly sensitive to recrystallization and can help diagnose different modes of diagenetic alteration, enabling evaluation of preservation states and identification of the most pristine materials from within a sample set-critical information for assessing the quality of paleoproxy data generated from carbonates. We measured the clumped isotope composition of a large suite of calcitic fossils (primarily brachiopods and corals), sedimentary grains, and cements from Silurian (ca. 433 Ma) stratigraphic sections on the island of Gotland, Sweden. Substantial variability in clumped isotope temperatures suggests differential preservation with alteration largely tied to rock-buffered diagenesis, complicating the generation of a stratigraphically resolved climate history through these sections. Despite the generally high preservation quality of samples from these sections, micro-scale observations of calcite fabric and trace metal composition using electron backscatter diffraction and electron microprobe analysis suggest that only a subset of relatively pristine samples retain primary clumped isotope signatures. These samples indicate that Silurian tropical oceans were likely warm (33 ± 7 °C) and similar in oxygen isotopic composition to that estimated for a “modern” ice-free world (δ18OVSMOW of -1

  11. Mechanisms linking metabolism of Helicobacter pylori to (18)O and (13)C-isotopes of human breath CO2.

    PubMed

    Som, Suman; De, Anulekha; Banik, Gourab Dutta; Maity, Abhijit; Ghosh, Chiranjit; Pal, Mithun; Daschakraborty, Sunil B; Chaudhuri, Sujit; Jana, Subhra; Pradhan, Manik

    2015-06-03

    The gastric pathogen Helicobacter pylori utilize glucose during metabolism, but the underlying mechanisms linking to oxygen-18 ((18)O) and carbon-13 ((13)C)-isotopic fractionations of breath CO2 during glucose metabolism are poorly understood. Using the excretion dynamics of (18)O/(16)O and (13)C/(12)C-isotope ratios of breath CO2, we found that individuals with Helicobacter pylori infections exhibited significantly higher isotopic enrichments of (18)O in breath CO2 during the 2h-glucose metabolism regardless of the isotopic nature of the substrate, while no significant enrichments of (18)O in breath CO2 were manifested in individuals without the infections. In contrast, the (13)C-isotopic enrichments of breath CO2 were significantly higher in individuals with Helicobacter pylori compared to individuals without infections in response to (13)C-enriched glucose uptake, whereas a distinguishable change of breath (13)C/(12)C-isotope ratios was also evident when Helicobacter pylori utilize natural glucose. Moreover, monitoring the (18)O and (13)C-isotopic exchange in breath CO2 successfully diagnosed the eradications of Helicobacter pylori infections following a standard therapy. Our findings suggest that breath (12)C(18)O(16)O and (13)C(16)O(16)O can be used as potential molecular biomarkers to distinctively track the pathogenesis of Helicobacter pylori and also for eradication purposes and thus may open new perspectives into the pathogen's physiology along with isotope-specific non-invasive diagnosis of the infection.

  12. Stable isotope composition of the meteoric precipitation in Croatia.

    PubMed

    Hunjak, Tamara; Lutz, Hans O; Roller-Lutz, Zvjezdana

    2013-01-01

    The precipitation is the input into the water system. Its stable isotope composition has to be known for the proper use and management of water resources. Croatia is not well represented in the Global Network of Isotopes in Precipitation (GNIP) database, and the geomorphology of the country causes specific local conditions. Therefore, at the Stable Isotope Laboratory (SILab), Rijeka, we monitor the stable isotope composition (δ(18)O, δ(2)H) of precipitation. Since δ(18)O and δ(2)H are well correlated, we concentrate the discussion on the δ(18)O distribution. Together with GNIP, our database contains 40 stations in Croatia and in the neighbouring countries. Their different latitudes, longitudes and altitudes give information of great detail, including the influence of the topographic structure on the precipitation in the south-eastern part of Europe, as well as the complex interplay of the different climate conditions in the area. Within a few hundred kilometres, the stable isotope values display a significant change from the maritime character in the south (mean δ(18)O around-6 to-8‰) to the continental behaviour in the north (mean δ(18)O around-8 to-11‰). Depending on the location, the mean δ(18)O values vary with altitude at a rate of approximately-0.2‰/100 m and-0.4‰/100 m, respectively. Also the deuterium excess has been found to depend on location and altitude. The data are being used to construct a δ(18)O map for the entire area. PMID:23937110

  13. sup 13 C and sup 18 O isotopic disequilibrium in biological carbonates: II. In vitro simulation of kinetic isotope effects

    SciTech Connect

    McConnaughey, T. )

    1989-01-01

    Biological carbonates are built largely from CO{sub 2}, which diffuses across the skeletogenic membrane and reacts to form HCO{sub 3}{sup {minus}}. Kinetic discrimination against the heavy isotopes {sup 18}O and {sup 13}C during CO{sub 2} hydration and hydroxylation apparently causes most of the isotopic disequilibrium observed in biological carbonates. These kinetic isotope effects are expressed when the extracytosolic calcifying solution is thin and alkaline, and HCO{sub 3}{sup {minus}} precipitates fairly rapidly as CaCO{sub 3}. In vitro simulation of the calcifying environment produced heavy isotope depletions qualitatively similar to, but somewhat more extreme than, those seen in biological carbonates. Isotopic equilibration during biological calcification occurs through CO{sub 2} exchange across the calcifying membrane and by admixture ambient waters (containing HCO{sub 3}{sup {minus}}) into the calcifying fluids. Both mechanisms tend to produce linear correlations between skeletal {delta}{sup 13}C and {delta}{sup 18}O.

  14. USGS46 Greenland ice core water – A new isotopic reference material for δ2H and δ18O measurements of water

    USGS Publications Warehouse

    Coplen, Tyler B.; Qi, Haiping; Tarbox, Lauren V.; Lorenz, Jennifer M.; Buck, Bryan

    2015-01-01

    Ice core from Greenland was melted, filtered, homogenised, loaded into glass ampoules, sealed, autoclaved to eliminate biological activity, and calibrated by dual-inlet isotope-ratio mass spectrometry. This isotopic reference material (RM), USGS46, is intended as one of two secondary isotopic reference waters for daily normalisation of stable hydrogen (δ2H) and stable oxygen (δ18O) isotopic analysis of water with a mass spectrometer or a laser absorption spectrometer. The measured δ2H and δ18O values of this reference water were −235.8 ± 0.7‰ and −29.80 ± 0.03‰, respectively, relative to VSMOW on scales normalised such that the δ2H and δ18O values of SLAP reference water are, respectively, −428 and −55.5‰. Each uncertainty is an estimated expanded uncertainty (U = 2uc) about the reference value that provides an interval that has about a 95-percent probability of encompassing the true value. This reference water is available in cases containing 144 glass ampoules that are filled with either 4 ml or 5 ml of water per ampoule.

  15. Stable isotopic characterisation of francolite formation

    NASA Astrophysics Data System (ADS)

    McArthur, J. M.; Benmore, R. A.; Coleman, M. L.; Soldi, C.; Yeh, H.-W.; O'Brien, G. W.

    1986-02-01

    Stable isotopic data are presented for 112 samples of francolite from 18 separate phosphate deposits. Values of δ 13C and δ 34S in most offshore deposits suggest formation within oxic or suboxic environments either by carbonate replacement or direct precipitation of francolite from water of normal marine compositions. The exceptions are concretionary francolite from Namibia, which has an isotopic composition in keeping with its formation within organic-rich sediments, and that from offshore Morocco, which has an isotopic signature of the anoxic/suboxic interface. Onshore deposits from Jordan, Mexico, South Africa and, possibly, the Permian Phosphoria Formation in the western U.S.A., are substantially depleted in 18O: they appear to be too altered for deductions to be made about their environments of formation. In other onshore deposits which are unaltered, or minimally altered, the isotopic composition suggests that some formed within sulphate-reducing sediments (Sedhura, Morocco) whilst francolite from the Georgina Basin of Australia formed at the oxic/anoxic boundary, where oxidation of biogenic H 2S decreases the δ 34S of pore water. In general, pelletal samples show non-oxic isotopic signatures, whilst non-pelletal samples show oxic isotopic signatures, but samples from Namibia, Peru (Ica Plateau) and the Californian and Moroccan margins are exceptions to this rule. Morphology may therefore be a misleading indicator of francolite genesis as no definitive relation exists between phosphorite type and isotopic signature.

  16. Deciphering Ecohydrological Interactions Using Stable Isotopes

    NASA Astrophysics Data System (ADS)

    McDonnell, J.; Evaristo, J. A.; Jasechko, S.

    2014-12-01

    Deciphering the nature of ecohydrological interconnections and scaling that knowledge gained at single points to watersheds is challenging. One tool that that has proved useful in this regard is stable isotope tracing. Single isotope studies have been used recently to quantify landuse change effects on streamflow source apportionment and ecological effects on transit time distributions of water at the catchment scale. However, most work to date has assumed that plant transpiration, groundwater recharge and streamflow are all sourced or mediated by the same well mixed reservoir—the soil. Recent work in Oregon and Mexico has shown evidence of ecohydrological separation, whereby different subsurface compartmentalized pools of water supply either plant transpiration fluxes or the combined fluxes of groundwater recharge and streamflow. However, these findings have not yet been widely tested. Here we assemble the first dual isotope database for δ2H and δ18O extracted from 47 globally-distributed stable isotopic datasets. We use these data to test the ecohydrological separation hypothesis. We combine this dual isotope dataset with global precipitation, streamwater, groundwater and soil water datasets. Our results show that precipitation, streamwater and groundwater from the 47 sites plot approximately along the δ2H/δ18O slope of eight, suggesting that local precipitation inputs supply streamwater and groundwater. Soil waters extracted from the 47 studies plot below the regression of local streamwater and groundwater with a slope of 6.6±0.05 ‰. Local plant xylem waters from our matched dataset plot on a slope 6.6±0.07 ‰ consistent with local soil waters. The tight association of soil water slopes and not that of local groundwater or streamflow suggests that plants use soil water that does not itself contribute to groundwater recharge or stream water. This ubiquity of subsurface water compartmentalization is surprising and has important implications for how we

  17. Biscayne aquifer drinking water (USGS45): a new isotopic reference material for δ2H and δ18O measurements of water

    USGS Publications Warehouse

    Lorenz, Jennifer M.; Tarbox, Lauren V.; Buck, Bryan; Qi, Haiping; Coplen, Tyler B.

    2014-01-01

    RATIONALE As a result of the scarcity of isotopic reference waters for daily use, a new secondary isotopic reference material for international distribution has been prepared from drinking water collected from the Biscayne aquifer in Ft. Lauderdale, Florida. METHODS This isotopic reference water was filtered, homogenized, loaded into glass ampoules, sealed with a torch, autoclaved to eliminate biological activity, and measured by dual-inlet isotope-ratio mass spectrometry. This reference material is available by the case of 144 glass ampoules containing either 4 mL or 5 mL of water in each ampoule. RESULTS The δ2H and δ18O values of this reference material are –10.3 ± 0.4 ‰ and –2.238 ± 0.011 ‰, respectively, relative to VSMOW, on scales normalized such that the δ2H and δ18O values of SLAP reference water are, respectively, –428 and –55.5 ‰. Each uncertainty is an estimated expanded uncertainty (U = 2uc) about the reference value that provides an interval that has about a 95 % probability of encompassing the true value. CONCLUSIONS This isotopic reference material, designated as USGS45, is intended as one of two isotopic reference waters for daily normalization of stable hydrogen and oxygen isotopic analysis of water with an isotope-ratio mass spectrometer or a laser absorption spectrometer. 

  18. Mechanisms linking metabolism of Helicobacter pylori to 18O and 13C-isotopes of human breath CO2

    PubMed Central

    Som, Suman; De, Anulekha; Banik, Gourab Dutta; Maity, Abhijit; Ghosh, Chiranjit; Pal, Mithun; Daschakraborty, Sunil B.; Chaudhuri, Sujit; Jana, Subhra; Pradhan, Manik

    2015-01-01

    The gastric pathogen Helicobacter pylori utilize glucose during metabolism, but the underlying mechanisms linking to oxygen-18 (18O) and carbon-13 (13C)-isotopic fractionations of breath CO2 during glucose metabolism are poorly understood. Using the excretion dynamics of 18O/16O and 13C/12C-isotope ratios of breath CO2, we found that individuals with Helicobacter pylori infections exhibited significantly higher isotopic enrichments of 18O in breath CO2 during the 2h-glucose metabolism regardless of the isotopic nature of the substrate, while no significant enrichments of 18O in breath CO2 were manifested in individuals without the infections. In contrast, the 13C-isotopic enrichments of breath CO2 were significantly higher in individuals with Helicobacter pylori compared to individuals without infections in response to 13C-enriched glucose uptake, whereas a distinguishable change of breath 13C/12C-isotope ratios was also evident when Helicobacter pylori utilize natural glucose. Moreover, monitoring the 18O and 13C-isotopic exchange in breath CO2 successfully diagnosed the eradications of Helicobacter pylori infections following a standard therapy. Our findings suggest that breath 12C18O16O and 13C16O16O can be used as potential molecular biomarkers to distinctively track the pathogenesis of Helicobacter pylori and also for eradication purposes and thus may open new perspectives into the pathogen’s physiology along with isotope-specific non-invasive diagnosis of the infection. PMID:26039789

  19. Effect of (2)H and (18)O water isotopes in kinesin-1 gliding assay.

    PubMed

    Maloney, Andy; Herskowitz, Lawrence J; Koch, Steven J

    2014-01-01

    We show for the first time the effects of heavy-hydrogen water ((2)H2O) and heavy-oxygen water (H2 (18)O) on the gliding speed of microtubules on kinesin-1 coated surfaces. Increased fractions of isotopic waters used in the motility solution decreased the gliding speed of microtubules by a maximum of 21% for heavy-hydrogen and 5% for heavy-oxygen water. We also show that gliding microtubule speed returns to its original speed after being treated with heavy-hydrogen water. We discuss possible interpretations of these results and the importance for future studies of water effects on kinesin and microtubules. We also discuss the implication for using heavy waters in biomolecular devices incorporating molecular motors. PMID:24711961

  20. Metal Stable Isotopes in Paleoceanography

    NASA Astrophysics Data System (ADS)

    Anbar, Ariel D.; Rouxel, Olivier

    2007-05-01

    Considered esoteric only a few years ago, research into the stable isotope geochemistry of transition metals is moving into the geoscience mainstream. Although initial attention focused on the potential use of some of these nontraditional isotope systems as biosignatures, they are now emerging as powerful paleoceanographic proxies. In particular, the Fe and Mo isotope systems are providing information about changes in oxygenation and metal cycling in ancient oceans. Zn, Cu, Tl, and a number of other metals and metalloids also show promise. Here we review the basis of stable isotope fractionation as it applies to these elements, analytical considerations, and the current status and future prospects of this rapidly developing research area.

  1. The evolution of Phanerozoic seawater - Isotope paleothermometry finds consensus on Early Paleozoic warmth and constant seawater δ18O

    NASA Astrophysics Data System (ADS)

    Grossman, E. L.; Henkes, G. A.; Passey, B. H.; Shenton, B.; Yancey, T. E.; Perez-Huerta, A.

    2015-12-01

    Evolution of metazoan life is closely linked to the Phanerozoic evolution of ocean temperatures and chemistry. Oxygen isotopic evidence for early Phanerozoic paleotemperatures has been equivocal, with decreasing δ18O values with age being interpreted as warmer early oceans, decreasing seawater δ18O with age, or increasing diagenetic alteration in older samples. Here we compare an updated compilation of oxygen isotope data for carbonate and phosphate fossils and microfossils (Grossman, 2012, Geol. Time Scale, Elsevier, 195-220) with a compilation of new and existing clumped isotope data. Importantly, these data are curated based on sample preservation with special consideration given to screening techniques, and tectonic and burial history. Burial history is critical in the preservation of carbonate clumped isotope temperatures in particular, which can undergo reordering in the solid state. We use a model derived for reordering kinetics (Henkes et al., 2014, Geochim. Cosmochim. Acta 139:362-382) to screen clumped isotope data for the effects of solid-state burial alteration. With minor but significant exceptions (Late Cretaceous, Early Triassic), average δ18O values (4 m.y. window, 2 m.y. steps) for post-Devonian brachiopods, belemnites, and foraminifera, representing tropical-subtropical surface ocean conditions, yield average isotopic temperatures below 30°C (assuming a seawater δ18O value [ -1‰ VSMOW] of an "ice-free" world). In contrast, Ordovician to Devonian data show sustained temperatures of 35-40°C. Likewise, isotopic paleotemperatures from conodont apatite, known to be resistant to isotopic exchange, follow the same pattern. Clumped isotope data derived from Paleozoic brachiopod shells that experienced minimal burial (< 100 °C) and <1% reordering according to the taxon-specific clumped isotope reordering model yield typical temperatures of 25-30°C for the Carboniferous, and 35-40°C for the Ordovician-Silurian. Inserting clumped temperatures and

  2. Stable isotopes in obesity research.

    PubMed

    Dolnikowski, Gregory G; Marsh, Julian B; Das, Sai Krupa; Welty, Francine K

    2005-01-01

    Obesity is recognized as a major public health problem. Obesity is a multifactorial disease and is often associated with a wide range of comorbidities including hypertension, non-insulin dependent (Type II) diabetes mellitus, and cardiovascular disease, all of which contribute to morbidity and mortality. This review deals with stable isotope mass spectrometric methods and the application of stable isotopes to metabolic studies of obesity. Body composition and total energy expenditure (TEE) can be measured by mass spectrometry using stable isotope labeled water, and the metabolism of protein, lipid, and carbohydrate can be measured using appropriate labeled tracer molecules.

  3. Quantifying uncertainty in stable isotope mixing models

    NASA Astrophysics Data System (ADS)

    Davis, Paul; Syme, James; Heikoop, Jeffrey; Fessenden-Rahn, Julianna; Perkins, George; Newman, Brent; Chrystal, Abbey E.; Hagerty, Shannon B.

    2015-05-01

    Mixing models are powerful tools for identifying biogeochemical sources and determining mixing fractions in a sample. However, identification of actual source contributors is often not simple, and source compositions typically vary or even overlap, significantly increasing model uncertainty in calculated mixing fractions. This study compares three probabilistic methods, Stable Isotope Analysis in R (SIAR), a pure Monte Carlo technique (PMC), and Stable Isotope Reference Source (SIRS) mixing model, a new technique that estimates mixing in systems with more than three sources and/or uncertain source compositions. In this paper, we use nitrate stable isotope examples (δ15N and δ18O) but all methods tested are applicable to other tracers. In Phase I of a three-phase blind test, we compared methods for a set of six-source nitrate problems. PMC was unable to find solutions for two of the target water samples. The Bayesian method, SIAR, experienced anchoring problems, and SIRS calculated mixing fractions that most closely approximated the known mixing fractions. For that reason, SIRS was the only approach used in the next phase of testing. In Phase II, the problem was broadened where any subset of the six sources could be a possible solution to the mixing problem. Results showed a high rate of Type I errors where solutions included sources that were not contributing to the sample. In Phase III some sources were eliminated based on assumed site knowledge and assumed nitrate concentrations, substantially reduced mixing fraction uncertainties and lowered the Type I error rate. These results demonstrate that valuable insights into stable isotope mixing problems result from probabilistic mixing model approaches like SIRS. The results also emphasize the importance of identifying a minimal set of potential sources and quantifying uncertainties in source isotopic composition as well as demonstrating the value of additional information in reducing the uncertainty in calculated

  4. Oxygen isotope fractionation in the ocean surface and 18O/16O of atmospheric O2

    NASA Astrophysics Data System (ADS)

    Luz, Boaz; Barkan, Eugeni

    2011-12-01

    We have recently published a new evaluation of Earth's Dole effect, which was based, in part, on measurements of δO2/Ar, δ17O and δ18O of dissolved argon and oxygen in the ocean surface. In calculations of the oxygen isotope effect due to photosynthesis and respiration (ɛup), gross O2 production (G) was an important factor. However, our estimates of G were based on an approximate equation, and in a recent publication it has been suggested that G obtained with this equation could be underestimated by about 33%. If true, such underestimation of G might lead to different ɛup values. To test this possibility, we have used a new rigorous equation with relevant information on isotopic composition of photosynthetic O2 and recalculated ɛup. Given the uncertainties, the new values do not differ from the previous ones, and therefore, the implications of the strong fractionation in the upper ocean (˜25‰) to the global Dole effect remain as in our original publication.

  5. Metal-catalyzed phosphodiester cleavage: secondary 18O isotope effects as an indicator of mechanism.

    PubMed

    Rawlings, Jill; Cleland, W Wallace; Hengge, Alvan C

    2006-12-27

    Information about the transition states of metal-catalyzed hydrolysis reactions of model phosphate compounds has been obtained through determination of isotope effects (IEs) on the hydrolysis reactions. Metal complexation has been found to significantly alter the transition state of the reaction from the alkaline hydrolysis reaction, and the transition state is quite dependent on the particular metal ion used. For the diester, ethyl p-nitrophenyl phosphate, the nonbridge 18O effect for the hydrolysis reactions catalyzed by Co(III) 1,5,9-triazacyclononane and Eu(III) were 1.0006 and 1.0016, respectively, indicative of a slightly associative transition state and little net change in bonding to the nonbridge oxygen. The reaction catalyzed by Zn(II) 1,4,7,10-tetraazacyclododecane had an 18O nonbridge IE of 1.0108, showing the reaction differs significantly from the reaction of the noncomplexed diester and resembles the reactions of triesters. Reaction with Co(III) 1,4,7,10-tetraazacyclododecane showed an inverse effect of 0.9948 reflecting the effects of bonding of the diester to the Co(III). Lanthanide-catalyzed hydrolysis has been observed to have unusually large 15N effects. To further investigate this effect, the 15N effect on the reaction catalyzed by Ce(IV) bis-Tris propane solutions at pH 8 was determined to be 1.0012. The 15N effects were also measured for the reaction of the monoester p-nitrophenyl phosphate by Ce(IV) bis-Tris propane (1.0014) and Eu(III) bis-Tris propane (1.0012). These smaller effects at pH 8 indicate that a smaller negative charge develops on the nitrogen during the hydrolysis reaction.

  6. Isolating relative humidity: dual isotopes d18O and dD as deuterium deviations from the global meteoric water line

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Cellulose d18O and dD can provide insights on climates and hydrological cycling in the distant past and how these factors differ spatially. However, most studies of plant cellulose have used only one isotope, most commonly d18O, resulting in difficulties partitioning variation in d18O of precipitati...

  7. A Novel Method for Relative Quantitation of N-Glycans by Isotopic Labeling Using 18O-Water

    PubMed Central

    Tao, Shujuan; Orlando, Ron

    2014-01-01

    Quantitation is an essential aspect of comprehensive glycomics study. Here, a novel isotopic-labeling method is described for N-glycan quantitation using 18O-water. The incorporation of the 18O-labeling into the reducing end of N-glycans is simply and efficiently achieved during peptide-N4-(N-acetyl-β-glucosaminyl) asparagine amidase F release. This process provides a 2-Da mass difference compared with the N-glycans released in 16O-water. A mathematical calculation method was also developed to determine the 18O/16O ratios from isotopic peaks. Application of this method to several standard glycoprotein mixtures and human serum demonstrated that this method can facilitate the relative quantitation of N-glycans over a linear dynamic range of two orders, with high accuracy and reproducibility. PMID:25365792

  8. Oxygen isotopes in tree rings record variation in precipitation δ18O and amount effects in the south of Mexico

    PubMed Central

    Brienen, Roel J W; Hietz, Peter; Wanek, Wolfgang; Gloor, Manuel

    2013-01-01

    [1] Natural archives of oxygen isotopes in precipitation may be used to study changes in the hydrological cycle in the tropics, but their interpretation is not straightforward. We studied to which degree tree rings of Mimosa acantholoba from southern Mexico record variation in isotopic composition of precipitation and which climatic processes influence oxygen isotopes in tree rings (δ18Otr). Interannual variation in δ18Otr was highly synchronized between trees and closely related to isotopic composition of rain measured at San Salvador, 710 km to the southwest. Correlations with δ13C, growth, or local climate variables (temperature, cloud cover, vapor pressure deficit (VPD)) were relatively low, indicating weak plant physiological influences. Interannual variation in δ18Otr correlated negatively with local rainfall amount and intensity. Correlations with the amount of precipitation extended along a 1000 km long stretch of the Pacific Central American coast, probably as a result of organized storm systems uniformly affecting rainfall in the region and its isotope signal; episodic heavy precipitation events, of which some are related to cyclones, deposit strongly 18O-depleted rain in the region and seem to have affected the δ18Otr signal. Large-scale controls on the isotope signature include variation in sea surface temperatures of tropical north Atlantic and Pacific Ocean. In conclusion, we show that δ18Otr of M. acantholoba can be used as a proxy for source water δ18O and that interannual variation in δ18Oprec is caused by a regional amount effect. This contrasts with δ18O signatures at continental sites where cumulative rainout processes dominate and thus provide a proxy for precipitation integrated over a much larger scale. Our results confirm that processes influencing climate-isotope relations differ between sites located, e.g., in the western Amazon versus coastal Mexico, and that tree ring isotope records can help in disentangling the processes

  9. Oxygen isotopes in tree rings record variation in precipitation δ18O and amount effects in the south of Mexico

    NASA Astrophysics Data System (ADS)

    Brienen, Roel J. W.; Hietz, Peter; Wanek, Wolfgang; Gloor, Manuel

    2013-12-01

    Natural archives of oxygen isotopes in precipitation may be used to study changes in the hydrological cycle in the tropics, but their interpretation is not straightforward. We studied to which degree tree rings of Mimosa acantholoba from southern Mexico record variation in isotopic composition of precipitation and which climatic processes influence oxygen isotopes in tree rings (δ18Otr). Interannual variation in δ18Otr was highly synchronized between trees and closely related to isotopic composition of rain measured at San Salvador, 710 km to the southwest. Correlations with δ13C, growth, or local climate variables (temperature, cloud cover, vapor pressure deficit (VPD)) were relatively low, indicating weak plant physiological influences. Interannual variation in δ18Otr correlated negatively with local rainfall amount and intensity. Correlations with the amount of precipitation extended along a 1000 km long stretch of the Pacific Central American coast, probably as a result of organized storm systems uniformly affecting rainfall in the region and its isotope signal; episodic heavy precipitation events, of which some are related to cyclones, deposit strongly 18O-depleted rain in the region and seem to have affected the δ18Otr signal. Large-scale controls on the isotope signature include variation in sea surface temperatures of tropical north Atlantic and Pacific Ocean. In conclusion, we show that δ18Otr of M. acantholoba can be used as a proxy for source water δ18O and that interannual variation in δ18Oprec is caused by a regional amount effect. This contrasts with δ18O signatures at continental sites where cumulative rainout processes dominate and thus provide a proxy for precipitation integrated over a much larger scale. Our results confirm that processes influencing climate-isotope relations differ between sites located, e.g., in the western Amazon versus coastal Mexico, and that tree ring isotope records can help in disentangling the processes

  10. Impact of Bolivian paleolake evaporation on the δ18O of the Andean glaciers during the last deglaciation (18.5-11.7 ka): diatom-inferred δ18O values and hydro-isotopic modeling

    NASA Astrophysics Data System (ADS)

    Quesada, Benjamin; Sylvestre, Florence; Vimeux, Françoise; Black, Jessica; Paillès, Christine; Sonzogni, Corinne; Alexandre, Anne; Blard, Pierre-Henri; Tonetto, Alain; Mazur, Jean-Charles; Bruneton, Hélène

    2015-07-01

    During the last deglaciation, the Bolivian Altiplano (15-23°S, 66-70°W) was occupied by paleolake Tauca covering, at least, ˜51,000 km2 at its maximum highstand between 16.5 and 15 ka. Twenty-five hundred years later, after a massive regression, a new transgressive phase, produced paleolake Coipasa, smaller than Tauca and restricted to the southern part of the basin. These paleolakes were overlooked at the west by the Sajama ice cap. The latter provides a continuous record of the oxygen isotopic composition of paleo-precipitation for the last 25 ka. Contemporaneously to the end of paleolake Tauca, around 14.3 ka, the Sajama ice cap recorded a significant increase in ice oxygen isotopic composition (δ18Oice). This paper examines to what extent the disappearance of Lake Tauca contributed to precipitation on the Sajama summit and this specific isotopic variation. The water δ18O values of paleolakes Tauca and Coipasa (δ18Olake) were quantitatively reconstructed from 18.5 to 11.7 ka based on diatom isotopic composition (δ18Odiatoms) and ostracod isotopic composition (δ18Ocarbonates) retrieved in lacustrine sediments. At a centennial time scale, a strong trend appears: abrupt decreases of δ18Olake during lake fillings are immediately followed by abrupt increases of δ18Olake during lake level stable phases. The highest variation occurred at ˜15.8 ka with a δ18Olake decrease of about ˜10‰, concomitant with the Lake Tauca highstand, followed ˜400 years later by a 7‰ increase in δ18Olake. A simple hydro-isotopic modeling approach reproduces consistently this rapid "decrease-increase" feature. Moreover, it suggests that this unexpected re-increase in δ18Olake after filling phases can be partly explained by an equilibration of isotopic fluxes during the lake steady-state. Based on isotopic calculations during lake evaporation and a simple water stable isotopes balance between potential moisture sources at Sajama (advection versus lake evaporation), we show

  11. Quantifying uncertainty in stable isotope mixing models

    DOE PAGES

    Davis, Paul; Syme, James; Heikoop, Jeffrey; Fessenden-Rahn, Julianna; Perkins, George; Newman, Brent; Chrystal, Abbey E.; Hagerty, Shannon B.

    2015-05-19

    Mixing models are powerful tools for identifying biogeochemical sources and determining mixing fractions in a sample. However, identification of actual source contributors is often not simple, and source compositions typically vary or even overlap, significantly increasing model uncertainty in calculated mixing fractions. This study compares three probabilistic methods, SIAR [Parnell et al., 2010] a pure Monte Carlo technique (PMC), and Stable Isotope Reference Source (SIRS) mixing model, a new technique that estimates mixing in systems with more than three sources and/or uncertain source compositions. In this paper, we use nitrate stable isotope examples (δ15N and δ18O) but all methods testedmore » are applicable to other tracers. In Phase I of a three-phase blind test, we compared methods for a set of six-source nitrate problems. PMC was unable to find solutions for two of the target water samples. The Bayesian method, SIAR, experienced anchoring problems, and SIRS calculated mixing fractions that most closely approximated the known mixing fractions. For that reason, SIRS was the only approach used in the next phase of testing. In Phase II, the problem was broadened where any subset of the six sources could be a possible solution to the mixing problem. Results showed a high rate of Type I errors where solutions included sources that were not contributing to the sample. In Phase III some sources were eliminated based on assumed site knowledge and assumed nitrate concentrations, substantially reduced mixing fraction uncertainties and lowered the Type I error rate. These results demonstrate that valuable insights into stable isotope mixing problems result from probabilistic mixing model approaches like SIRS. The results also emphasize the importance of identifying a minimal set of potential sources and quantifying uncertainties in source isotopic composition as well as demonstrating the value of additional information in reducing the uncertainty in calculated

  12. 18O isotopic separation of stream nitrate sources in mid-Appalachian forested watersheds

    NASA Astrophysics Data System (ADS)

    Williard, Karl W. J.; DeWalle, David R.; Edwards, Pamela J.; Sharpe, William E.

    2001-10-01

    The δ18O values of atmospheric nitrate deposition, microbe-produced nitrate, and stream nitrate were measured to determine the dominant source of stream nitrate in 27 mid-Appalachian headwater forested watersheds (12-771 ha) with varying bedrock geologies, land disturbance histories, and stand ages. The 12 monthly composite nitrate δ18O values of wet deposition and throughfall exhibited similar pronounced seasonal trends, with relatively depleted δ18O values during the summer. Wet deposition and throughfall nitrate δ18O values were not significantly different between northern (Leading Ridge, PA) and southern (Fernow, WV) regional sampling sites, indicating that δ18O values were spatially similar across the study area. Atmospheric nitrate δ18O values were significantly greater than microbe-produced nitrate δ18O values, allowing the two sources of stream nitrate to be separated. During four baseflow and three stormflow sampling periods, microbe-produced nitrate was the dominant (>70%) source of nitrate in the study streams. This result does not mean atmospheric nitrogen deposition should be discounted as a source of forested stream nitrate, because atmospheric deposition is the primary external contributor to the long-term soil nitrogen pool that ultimately drives soil nitrate production rates. Stream nitrate δ18O values were greater during stormflow periods compared to baseflow periods, indicating greater contributions of atmospheric nitrate during storm events. Neither microbe-produced nitrate δ18O values from incubated forest soil samples nor stream nitrate δ18O values showed strong relationships with land disturbance history or stand age. However, watersheds dominated by Pottsville/Allegheny bedrock and associated extremely acid soils had greater summer stream nitrate δ18O values than watersheds containing predominantly Catskill/Chemung/Pocono and Mauch Chunk/Greenbrier bedrock. Inhibited microbial nitrate production by low soil pH could account for

  13. Observation of Isotope Ratios (δ2H, δ18O, 87Sr/86Sr) of Tap Water in Urban Environments

    NASA Astrophysics Data System (ADS)

    Mancuso, C. J.; Tipple, B. J.; Ehleringer, J. R.

    2014-12-01

    Urban environments are centers for rapidly growing populations. In order to meet the culinary water needs of these areas, municipal water departments use water from multiple locations and/or sources, often piped differentially to different locations within a municipality. This practice creates isotopically distinct locations within an urban area and therefore provides insight to urban water management practices. In our study we selected urban locations in the Salt Lake Valley, UT (SLV) and San Francisco Bay Area, CA (SFB) where we hypothesized geographically distinct water isotopic ratio differences existed. Within the SLV, municipal waters come from the same mountainous region, but are derived from different geologically distinct watersheds. In contrast, SFB waters are derived from regionally distinct water sources. We hypothesized that the isotope ratios of tap waters would differ based upon known municipal sources. To test this, tap water samples were collected throughout the urban regions in SLV and SFB and analyzed for δ2H, δ18O and 87Sr/86Sr isotope ratios. Seasonal collections were also made to assess if isotope ratios differed throughout the year. Within SLV and SFB, different regions were characterized by distinct paired δ18O and 87Sr/86Sr values. These different realms also agreed with known differences in municipal water supplies within the general geographic region. Waters from different cities within Marin County showed isotopic differences, consistent with water derived from different local reservoirs. Seasonal variation was observed in paired δ18O and 87Sr/86Sr values of tap water for some locations within SLV and SFB, indicating management decisions to shift from one water source to another depending on demand and available resources. Our study revealed that the δ18O and 87Sr/86Sr values of tap waters in an urban region can exhibit significant differences despite close spatial proximity if districts differ in their use of local versus

  14. What can Δ 15N and Δ 18O isotopes tell us about sources, transport, and fate of nitrate in the Mississippi River Basin?

    NASA Astrophysics Data System (ADS)

    Battaglin, W. A.

    2003-12-01

    Water and nutrients, primarily nitrate (NO3) in Mississippi River discharge, affect the size and severity of the Gulf of Mexico hypoxic (depleted dissolved oxygen) zone. Approximately 120 water samples were collected from 16 sites on small streams and 6 sites on large rivers within the Mississippi River Basin in 1997-98 to see if NO3 sources and transformations can be identified using the stable isotopic ratios Δ 15N and Δ 18O. Results from Lagrangian sampling at the large river sites indicate that nitrate mass decreases slightly, while Δ 15N and Δ 18O isotope ratios are unchanged in the 1500 river kilometers between the Upper Mississippi-Ohio River confluence and the Gulf of Mexico. Results also show that Δ 15N and Δ 18O values from small streams draining lands dominated by row crops or livestock tended to be distinct from those dominated by urban or undeveloped land. Mean Δ 15N values at the 16 sites on small streams were most strongly correlated (Pearson's r) with manure production rate (0.64), percent residential land use (-0.45), and urea use rate (0.43). The best multiple linear regression (MLR) model for mean Δ 15N values (r2=0.69) used manure production rate and ammonium nitrate use rate as explanatory variables. Mean Δ 18O values were most strongly correlated with percent wetlands (0.72), mean NO3 concentration (-0.71), and percent residential land use (0.58). The best MLR model for mean Δ 18O values (r2=0.85) used percent residential land use, percent wetlands, and ammonium nitrate use rate as explanatory variables. Mean NO3 concentrations were most strongly correlated with percent row-crops land use (0.84), nitrogen-fertilizer use rate (0.74), and hog-manure production rate (0.66). The best MLR model for mean NO3 concentration (r2=0.85) used percent row-crops land use and percent grain-crops land use as explanatory variables. MLR equations developed from the 16 smaller streams were used to predict mean Δ 15N and Δ 18O values and NO3

  15. Stable isotope deltas: tiny, yet robust signatures in nature.

    PubMed

    Brand, Willi A; Coplen, Tyler B

    2012-09-01

    Although most of them are relatively small, stable isotope deltas of naturally occurring substances are robust and enable workers in anthropology, atmospheric sciences, biology, chemistry, environmental sciences, food and drug authentication, forensic science, geochemistry, geology, oceanography, and paleoclimatology to study a variety of topics. Two fundamental processes explain the stable isotope deltas measured in most terrestrial systems: isotopic fractionation and isotope mixing. Isotopic fractionation is the result of equilibrium or kinetic physicochemical processes that fractionate isotopes because of small differences in physical or chemical properties of molecular species having different isotopes. It is shown that the mixing of radioactive and stable isotope end members can be modelled to provide information on many natural processes, including (14)C abundances in the modern atmosphere and the stable hydrogen and oxygen isotopic compositions of the oceans during glacial and interglacial times. The calculation of mixing fractions using isotope balance equations with isotope deltas can be substantially in error when substances with high concentrations of heavy isotopes (e.g. (13)C, (2)H, and (18)O ) are mixed. In such cases, calculations using mole fractions are preferred as they produce accurate mixing fractions. Isotope deltas are dimensionless quantities. In the International System of Units (SI), these quantities have the unit 1 and the usual list of prefixes is not applicable. To overcome traditional limitations with expressing orders of magnitude differences in isotope deltas, we propose the term urey (symbol Ur), after Harold C. Urey, for the unit 1. In such a manner, an isotope delta value expressed traditionally as-25 per mil can be written as-25 mUr (or-2.5 cUr or-0.25 dUr; the use of any SI prefix is possible). Likewise, very small isotopic differences often expressed in per meg 'units' are easily included (e.g. either+0.015 ‰ or+15 per meg

  16. Stable isotope deltas: Tiny, yet robust signatures in nature

    USGS Publications Warehouse

    Brand, Willi A.; Coplen, Tyler B.

    2012-01-01

    Although most of them are relatively small, stable isotope deltas of naturally occurring substances are robust and enable workers in anthropology, atmospheric sciences, biology, chemistry, environmental sciences, food and drug authentication, forensic science, geochemistry, geology, oceanography, and paleoclimatology to study a variety of topics. Two fundamental processes explain the stable isotope deltas measured in most terrestrial systems: isotopic fractionation and isotope mixing. Isotopic fractionation is the result of equilibrium or kinetic physicochemical processes that fractionate isotopes because of small differences in physical or chemical properties of molecular species having different isotopes. It is shown that the mixing of radioactive and stable isotope end members can be modelled to provide information on many natural processes, including 14C abundances in the modern atmosphere and the stable hydrogen and oxygen isotopic compositions of the oceans during glacial and interglacial times. The calculation of mixing fractions using isotope balance equations with isotope deltas can be substantially in error when substances with high concentrations of heavy isotopes (e.g. 13C, 2H, and 18O ) are mixed. In such cases, calculations using mole fractions are preferred as they produce accurate mixing fractions. Isotope deltas are dimensionless quantities. In the International System of Units (SI), these quantities have the unit 1 and the usual list of prefixes is not applicable. To overcome traditional limitations with expressing orders of magnitude differences in isotope deltas, we propose the term urey (symbol Ur), after Harold C. Urey, for the unit 1. In such a manner, an isotope delta value expressed traditionally as−25 per mil can be written as−25 mUr (or−2.5 cUr or−0.25 dUr; the use of any SI prefix is possible). Likewise, very small isotopic differences often expressed in per meg ‘units’ are easily included (e.g. either+0.015 ‰ or+15 per meg

  17. Stable isotope deltas: tiny, yet robust signatures in nature.

    PubMed

    Brand, Willi A; Coplen, Tyler B

    2012-09-01

    Although most of them are relatively small, stable isotope deltas of naturally occurring substances are robust and enable workers in anthropology, atmospheric sciences, biology, chemistry, environmental sciences, food and drug authentication, forensic science, geochemistry, geology, oceanography, and paleoclimatology to study a variety of topics. Two fundamental processes explain the stable isotope deltas measured in most terrestrial systems: isotopic fractionation and isotope mixing. Isotopic fractionation is the result of equilibrium or kinetic physicochemical processes that fractionate isotopes because of small differences in physical or chemical properties of molecular species having different isotopes. It is shown that the mixing of radioactive and stable isotope end members can be modelled to provide information on many natural processes, including (14)C abundances in the modern atmosphere and the stable hydrogen and oxygen isotopic compositions of the oceans during glacial and interglacial times. The calculation of mixing fractions using isotope balance equations with isotope deltas can be substantially in error when substances with high concentrations of heavy isotopes (e.g. (13)C, (2)H, and (18)O ) are mixed. In such cases, calculations using mole fractions are preferred as they produce accurate mixing fractions. Isotope deltas are dimensionless quantities. In the International System of Units (SI), these quantities have the unit 1 and the usual list of prefixes is not applicable. To overcome traditional limitations with expressing orders of magnitude differences in isotope deltas, we propose the term urey (symbol Ur), after Harold C. Urey, for the unit 1. In such a manner, an isotope delta value expressed traditionally as-25 per mil can be written as-25 mUr (or-2.5 cUr or-0.25 dUr; the use of any SI prefix is possible). Likewise, very small isotopic differences often expressed in per meg 'units' are easily included (e.g. either+0.015 ‰ or+15 per meg

  18. Stable Chlorine Isotope Fractionation

    NASA Astrophysics Data System (ADS)

    Sharp, Z.

    2006-12-01

    Chlorine isotope partitioning between different phases is not well understood. Pore fluids can have δ37Cl values as low as -8‰, with neoform sediments having strongly positive values. Most strikingly, volcanic gases have δ37Cl values that cover a range in excess of 14‰ (Barnes et al., this meeting). The large range is difficult to explain in terms of equilibrium fractionation, which, although calculated to be very large for Cl in different oxidation states, should be less than 2‰ between chloride species (Schauble et al., 2003, GCA). To address the discrepancy between Nature and theory, we have measured Cl isotope fractionation for selected equilibrium and disequilibrium experiments in order to identify mechanisms that might lead to large fractionations. 1) NaCl (s,l) NaCl (v): NaCl was sealed in an evacuated silica tube and heated at one end, causing vaporization and reprecipitation of NaCl (v) at the cool end of the tube. The fractionation is 0.2‰ at 700°C (halite-vapor) and 0.7‰ at 800°C (liquid-vapor), respectively. The larger fractionation at higher temperature may be related to equilibrium fractionation between liquid and gas vs. `stripping' of the solid in the lower T experiments. 2) Sodalite NaCl(l): Nepheline and excess NaCl were sealed in a Pt crucible at 825°C for 48 hrs producing sodalite. The measured newly-formed sodalite-NaCl fractionation is -0.2‰. 3) Volatilization of HCl: Dry inert gas was bubbled through HCl solutions and the vapor was collected in a downstream water trap. There was no fractionation for 12.4M HCl (HCl fuming) vapor at 25°C. For a 1 M boiling HCl solution, the HCl-vapor fractionation was ~9‰. The difference is probably related to the degree of dissociation in the acid, with HCl dissolved in water for the highly acidic solutions, and dissociated H3O+ and Cl- for lower concentrations. The HCl volatilization experiments are in contrast to earlier vapor-liquid experiments in NaCl-H2O system, where fractionation was

  19. Bayesian stable isotope mixing models

    EPA Science Inventory

    In this paper we review recent advances in Stable Isotope Mixing Models (SIMMs) and place them into an over-arching Bayesian statistical framework which allows for several useful extensions. SIMMs are used to quantify the proportional contributions of various sources to a mixtur...

  20. Tritium and stable isotopes of magmatic waters

    NASA Astrophysics Data System (ADS)

    Goff, F.; McMurtry, G. M.

    2000-04-01

    To investigate the isotopic composition and age of water in volcanic gases and magmas, we analyzed samples from 11 active volcanoes ranging in composition from tholeiitic basalt to rhyolite: Mount St. Helens (USA), Kilauea (USA), Pacaya (Guatemala), Galeras (Colombia), Satsuma Iwo-Jima (Japan), Sierra Negra and Alcedo (Ecuador), Vulcano (Italy), Parı´cutin (Mexico), Kudryavy (Russia), and White Island (New Zealand). Tritium at relatively low levels (0.1-5 T.U.) is found in most emissions from high-temperature volcanic fumaroles sampled, even at discharge temperatures >700°C. Although magmatic fluids sampled from these emissions usually contain high CO 2, S total, HCl, HF, B, Br, 3He R/ RA, and low contents of air components, stable isotope and tritium relations of nearly all such fluids show mixing of magmatic volatiles with relatively young meteoric water (model ages≤75 y). Linear δD/ δ18O and 3H/ δ18O mixing trends of these two end-members are invariably detected at arc volcanoes. Tritium is also detected in fumarole condensates at hot spot basalt volcanoes, but collecting samples approaching the composition of end-member magmatic fluid is exceedingly difficult. In situ production of 3H, mostly from spontaneous fission of 238U in magmas is calculated to be <0.001 T.U., except for the most evolved compositions (high U, Th, and Li and low H 2O contents). These values are below the detection limit of 3H by conventional analytical techniques (about 0.01 T.U. at best). We found no conclusive evidence that natural fusion in the Earth produces anomalous amounts of detectable 3H (>0.05 T.U.).

  1. Paleoproxies: Heavy Stable Isotope Perspectives

    NASA Astrophysics Data System (ADS)

    Nagler, T. F.; Hippler, D.; Siebert, C.; Kramers, J. D.

    2002-12-01

    Recent advances in isotope ratio mass spectrometry, namely multiple collector ICP-MS and refined TIMS techniques, will significantly enhance the ability to measure heavy stable isotope fractionation, which will lead to the development of a wide array of process-identifying (bio)-geochemical tools. Thus far research in this area is not easily assessable to scientists outside the isotope field. This is due to the fact that analyzing heavy stable isotopes does not provide routine numbers which are per se true (the preciser the truer) but is still a highly experimental field. On the other hand resolving earth science problems requires specialists familiar with the environment being studied. So what is in there for paleoceanographers? In a first order approach, relating isotope variations to physical processes is straightforward. A prominent example are oxygen isotope variations with temperature. The total geological signal is of course far more complicated. At low temperatures, heavy stable isotopes variations have been reported for e.g. Ca, Cr, Fe, Cu, Zn, Mo and Tl. Fractionation mechanisms and physical parameters responsible for the observed variations are not yet resolved for most elements. Significant equilibrium isotope fractionation is expected from redox reactions of transition metals. However a difference in coordination number between two coexisting speciations of an element in the same oxidation state can also cause fractionation. Protonation of dissolved Mo is one case currently discussed. For paleoceanography studies, a principal distinction between transition metals essential for life (V to Zn plus Mo) or not will be helpful. In case of the former group, distinction between biogenic and abiogenic isotope fractionation will remain an important issue. For example, abiotic Fe redox reactions result in isotope fractionations indistinguishable in direction and magnitude from microbial effects. Only a combination of different stable isotope systems bears the

  2. Autonomous Instrumentation for Fast, Continuous and Accurate Isotopic Measurements of Water Vapor (δ18O, δ 2H, H2O) in the Field

    NASA Astrophysics Data System (ADS)

    Liem, J. S.; Dong, F.; Owano, T. G.; Baer, D. S.

    2010-12-01

    Stable isotopes of water vapor are powerful tracers to investigate the hydrological cycle and ecological processes. Therefore, continuous, in-situ and accurate measurements of δ18O and δ2H are critical to advance the understanding of water-cycle dynamics worldwide. Furthermore, the combination of meteorological techniques and high-frequency isotopic water measurements can provide detailed time-resolved information on the eco-physiological performance of plants and enable improved understanding of water fluxes at ecosystem scales. In this work, we present recent development and field deployment of a novel Water Vapor Isotope Measurement System (WVIMS) capable of simultaneous in situ measurements of δ18O and δ2H and water mixing ratio (H2O) with high precision, accuracy and speed (up to 10 Hz measurement rate). The WVIMS consists of an Analyzer (Water Vapor Isotope Analyzer), based on cavity enhanced laser absorption spectroscopy, and a Standard Source (Water Vapor Isotope Standard Source), based on quantitative evaporation of a liquid water standard (with known isotopic content), and operates in a dual-inlet configuration. The WVIMS automatically controls the entire sample and data collection, data analysis and calibration process to allow for continuous, autonomous unattended long-term operation. The WVIMS has been demonstrated for accurate (i.e. fully calibrated) measurements ranging from 500 ppmv (typical of arctic environments) to over 30,000 ppmv (typical of tropical environments) in air. Dual-inlet operation, which involves regular calibration with isotopic water vapor reference standards, essentially eliminates measurement drift, ensures data reliability, and allows operation over an extremely wide ambient temperature range (5-45C). This presentation will include recent measurements recorded using the WVIMS in plant growth chambers and in arctic environments. The availability of this new instrumentation provides new opportunities for detailed continuous

  3. Lower to middle Miocene isotope ( sup 87 Sr/ sup 86 Sr,. delta. sup 18 O,. delta. sup 13 C) standard sections, DSDP site 608

    SciTech Connect

    Miller, K.G.; Feigenson, M.D. ); Wright, J.D. )

    1990-05-01

    Isotopes changes ({sup 87}Sr/{sup 86}Sr, {delta}{sup 18}O, {delta}{sup 13}C) have been correlated to the geologic time scale primarily by biostratigraphy. Biostratigraphic correlations suffer from problems of diachrony and taxonomy. Magnetostratigraphy provides a facies-independent correlation tool, but there are few Tertiary sections with unambiguous magnetostratigraphy. The authors previously developed an isotope standard for the Oligocene at the only location with a pristine magnetochronology, Site 522. They extend this approach to Site 608 in the northeastern North Atlantic, which contains a relatively straightforward Miocene magnetochronology. They establish Miocene oxygen isotope Chronozones MI1 through MI6 at Sites 522 and 608, which are directly tied to the geomagnetic polarity time scale (GPTS). The integration of stable isotopes, Sr isotopes, biostratigraphy, and magnetostratigraphy at site 608 provides a standard section with which other Sr isotope and oxygen isotope records can be correlated. For example, using oxygen isotopes to correlate, the Sr isotope record from Site 608 compares well with previously published records from Sites 516 and 590. The firm ties of the Oligocene to middle Miocene isotope records with the GPTS allows them to establish the nature of the change in Sr isotopes between 38 and 8 Ma. There were moderately high rates of {sup 87}Sr/{sup 86}Sr change during the Oligocene ({approximately}0.000030/m.y.), yielding stratigraphic resolution of {plus minus}1.0 m.y. The rate of change of {sup 87}Sr/{sup 86}Sr increased during the early Miocene. They estimate that the rate of change between 23 and 15 Ma was greater than 0.000060/m.y. Given their ability to reproduce Sr isotope measurements ({plus minus}0.000020 to {plus minus}0.000030), temporal resolution is better than {plus minus}0.5 my. for the early to early middle Oliocene.

  4. Continuous Arctic Ocean Water Vapor Isotope Ratio (δ18O and δ2H) Measurements During a Summer Icebreaker Expedition

    NASA Astrophysics Data System (ADS)

    Klein, E. S.; Welker, J. M.

    2015-12-01

    Warming in the Arctic is reducing sea ice, which may result in changes to the water cycle through increased atmospheric humidity. Here we present the first continuous record of water vapor isotope ratio (δ18O, δ2H, d-excess) measurements from the sub-Arctic and Arctic Ocean during ship transit through both open water and sea ice. As water vapor isotopes were collected across a spectrum of sea ice conditions, the influence of sea ice and availability of open water moisture sources on Arctic Ocean water vapor isotope values (particularly d-excess) is examined. Isotope values reveal characteristics about water availability at vapor sources, as influenced by presence of sea ice (e.g., ice covered arid or open water humid sources), and air parcel trajectory. Higher d-excess values were generally associated with more northern Arctic, ice covered, and arid vapor sources. Conversely, lower d-excess values were related to more southern, open water, and humid vapor sources. Additionally, water vapor isotopes while sea ice was present were generally characterized by more depleted δ18O and δ2H and higher d-excess values, relative to open water values. These water vapor isotope values also present information about potential shifts in moisture sources in an increasingly ice free Arctic Ocean. Understanding these shifts is important to learning about both modern and past patterns of Arctic atmospheric water movement and distribution.

  5. Highly enriched multiply-labeled stable isotopic compounds as atmospheric tracers

    DOEpatents

    Goldblatt, M.; McInteer, B.B.

    1974-01-29

    Compounds multiply-labeled with stable isotopes and highly enriched in these isotopes are readily capable of detection in tracer experiments involving high dilutions. Thus, for example, /sup 13/C/sup 18/O/sub 2/ provides a useful tracer for following atmospheric pol lution produced as a result of fossil fuel burning. (Official Gazette)

  6. Stable-isotope ratios of hydrogen and oxygen in precipitation at Norman, Oklahoma, 1996-2008

    USGS Publications Warehouse

    Jaeschke, Jeanne B.; Scholl, Martha A.; Cozzarelli, Isabelle M.; Masoner, Jason R.; Christenson, Scott; Qi, Haiping

    2011-01-01

    Precipitation samples for measurement of stable-isotope ratios of hydrogen (delta2H) and oxygen (delta18O) were collected at the Norman Landfill Research Site in Norman, Oklahoma, from May 1996 to October 2008. Rainfall amounts also were measured at the site (U.S. Geological Survey gaging station 07229053) during the collection period. The delta2H of precipitation samples ranged from -121.9 to +8.3 per mil, and the delta18O of precipitation ranged from -16.96 to +0.50 per mil. The volume-weighted average values for delta2H and delta18O of precipitation over the 12-year measurement period were -31.13 per mil for delta2H and -5.57 per mil for delta18O. Average summer-season delta2H and delta18O values of precipitation usually were more positive (enriched in the heavier isotopes) than winter values.

  7. Stable isotope paleoaltimetry and the evolution of landscapes and life

    NASA Astrophysics Data System (ADS)

    Mulch, Andreas

    2016-01-01

    Reconstructing topography of our planet not only advances our knowledge of the geodynamic processes that shape the Earth's surface; equally important it adds a key element towards understanding long-term continental moisture transport, atmospheric circulation and the distribution of biomes and biodiversity. Stable isotope paleoaltimetry exploits systematic decreases in the oxygen (δ18O) or hydrogen (δD) isotopic composition of precipitation along a mountain front when the interaction of topography and advected moist air masses induces orographic precipitation. These changes in δ18O or δD can be recovered from the geologic record and recent geochemical and modeling advances allow a broad range of proxy materials to be evaluated. Over the last 10 yr stable isotope paleoaltimetry has witnessed rapidly expanding research activities and has produced a broad array of fascinating tectonic and geomorphologic studies many of which have concentrated on determining the elevation history of continental plateau regions. These single-site studies have greatly expanded what used to be very sparse global paleoaltimetric data. The challenge now lies in disentangling the surface uplift component from the impact of climate change on δ18O and δD in precipitation. The robustness of stable isotope paleoaltimetry can be enhanced when high-elevation δ18O or δD data are referenced against low-elevation sites that track climate-modulated sea level δ18O or δD of precipitation through time (' δ- δ approach'). Analysis of central Andean paleosols documents that differences in δ18O of soil carbonate between the Subandean foreland and the Bolivian Altiplano are small between 11 and 7 Ma but rise rapidly to ca. 2.9‰ after 7 Ma, corroborating the magnitude of late Miocene change in δ18O on the Altiplano. Future advances in stable isotope paleoaltimetry will greatly benefit from addressing four key challenges: (1) Identifying topographically-induced changes in atmospheric

  8. Isotopic tracing (D, 18O and 29Si) to understand the alteration on historic glass

    NASA Astrophysics Data System (ADS)

    Verney-Carron, Aurélie; Saheb, Mandana; Valle, Nathalie; Mangin, Denis; Remusat, Laurent; Loisel, Claudine

    2015-04-01

    In order to better preserve historic glasses, e.g. stained glass windows, the understanding of their alteration mechanisms and of what controls the kinetics corresponding to each process is required. The ancient stained glasses are characterized by thick alteration layers, continuous or as pits, that are cracked or lost. Therefore, if a passivating role of the alteration layer has been proved on some other kinds of glass (such as basaltic or nuclear glass) in aqueous medium, the issue can be addressed for low durable stained glass weathered in varying atmospheric conditions. The mechanism of alteration layer formation was first investigated by performing dynamic and static experiments on model medieval glasses altered with a solution doped in 29Si at different concentrations (or saturation degrees). Solid analyses were carried out by SIMS and solution by HR-ICP-MS. Medieval stained glass has mainly a potash-lime-silica composition with a low content in alumina. The alkaline and alkaline-earth elements have thus a modifier role in the glassy network. This structural difference compared to boro- or alumino-silicate glasses could induce differences in the alteration mechanisms. However, the analysis of the Si isotopic signature of the gel layer highlighted that diffusion, but also hydrolysis/condensation reactions, are also involved in the gel layer formation process, leading to a structural and textural reorganization. The second objective was to determine the kinetic role of the alteration layer, and especially to trace the circulation of water once the altered layer is formed. For that, ancient glasses were exposed to simulated rainfall events / drying periods cycles during 3 months by using a solution doped in D and 18O. NanoSIMS analyses have shown that the transport in the alteration layer is mainly driven by diffusion in the porosity despite the presence of cracks that could have been preferential ways of circulation. This demonstrates also a potential

  9. Landscape hydrology and scaling of nitrate 15N and 18O isotope composition in a semi-arid agroecosystem

    NASA Astrophysics Data System (ADS)

    Kelley, C. J.; Martin, R. A.; Keller, C. K.; Orr, C. H.; Huggins, D. R.; Evans, R. D.

    2014-12-01

    Understanding how pore- to hillslope-scale processes combine to control nutrient export at larger scales is a fundamental challenge in today's agroecosystems as the carbon and contamination footprints of production agriculture come under increasing scrutiny. At the Cook Agronomy Farm (CAF) Long-Term Agricultural Research (LTAR) station near Pullman, WA we are using in-field observations to track how local-scale hydrological routing and biogeochemical processing interact to control landscape-scale water and nutrient exports. Previous research at the CAF has shown that conservative tracers and reactive nutrient quantities (NO3-,and DOC concentrations, DOM quality) in landscape-scale drainage can be explained by straightforward mixing of waters from variably contributing areas. Nitrate stable isotope composition in subsurface drain effluent indicate that most leached nitrate originates from reduced nitrogen fertilizer applied to the CAF in the autumn, which undergoes nitrification and subsequent leaching. This occurs over a timespan of weeks to months. However, water samples from contributing areas exhibit nitrate d15N and d18O significantly greater than subsurface drain effluent at all locations, and time-series consistent with the occurrence of denitrification at some locations. Possible explanations include pore-scale processing of nitrogen that does not affect the other tracers (like EC, DOM quality, and DOC concentration), and landscape-scale transport pathways that bypass our field instruments. Through this work we are contributing to a broader understand of how global change and local factors and management practices interact to affect the fate of fertilizer N, which is a cross-cutting research theme of the national LTAR network.

  10. Isotopic analyses (/sup 18/O, /sup 13/C, /sup 14/C) of two meromictic lakes in the Canadian Arctic Archipelago

    SciTech Connect

    Page, P.; Ouellet, M.; Hillaire-Marcel, C.; Dickman, M.

    1984-05-01

    Meromictic Lakes Garrow and Sophia in the Canadian Arctic Archipelago were sampled to establish the origin and age of their water by isotopic studies. /sup 18/O values reflect the permanent stratification of the water in both lakes. The mixolimnia contain waters with an isotopic signal between -13.16 and -21.98%, coherent with the values for precipitation in these high latitudes. In the chemoclines, the delta/sup 18/O values increase to -10% concomitantly with a rise in chloride content to 42 g.liter/sup -1/. In the monimolimnia, hypersaline waters (up to 2.5 times the salinity of seawater) show negative delta/sup 18/O values (ca. -.08%). These waters result from brine production during permafrost growth in the watershed, according to a Rayleigh process. /sup 14/C dating of total inorganic carbon in the Lake Garrow monimolimnion gave an age of 2580 +/- 260 years BP. In Lake Sophia, the deep waters exhibit recent /sup 14/C activity that suggests recent infiltration of seawater into the lake basin.

  11. Directly Measured Clumped Isotope Temperatures From Known And Proposed Paleozoic Glacial Intervals Suggest That Oceans Were Depleted in 18O

    NASA Astrophysics Data System (ADS)

    Petrizzo, D. A.; Runnegar, B.; Ivany, L.; Young, E. D.

    2011-12-01

    Oceans enriched in 13C are thought to result from atmospheric CO2 drawdown and concomitant global cooling resulting from increased burial of organic matter. We investigated ocean temperatures during two times when the oceans were exceptionally heavy in 13C, the Lau Event of the late Silurian and the Late Paleozoic Ice Age (LPIA), using both δ18O and "directly measured" clumped isotope (Δ47) temperatures. We report a tropical ocean temperature of 16 ± 3°C at the peak of the Lau Event, confirm seasonality at a high-latitude LPIA site, and raise the possibility that some degradation of 13C-18O bonds may be widespread in apparently unaltered carbonates that have seen temperatures higher than 100-150°C. Silurian conodonts from Gotland, Sweden, are almost unaltered (CAI ~ 0) indicating burial temperatures of <50°C. We measured atrypid brachiopod calcite from the peak of the late Silurian Lau event, the largest positive carbon isotope excursion (+8%) since the Cambrian, and obtained Δ47 = 0.687 ± 0.014, giving a low latitude water temperature of 16 ± 3°C. This is significantly cooler than tropical temperatures reported from pentamerid brachiopod calcite of the early Silurian greenhouse period (35°C, Came et al., 2007) and those derived from rugose corals during the Hirnantian (Ordovician) positive carbon isotope excursion (+5%) and accompanying glaciation (27-32°C, Finnegan et al., 2010). We also measured Δ47 in two shells of the Australian Permian bivalve Eurydesma, a circumpolar genus associated with cold water indicators. Ivany and Runnegar (2010) found high-amplitude annual cycles in δ18O in one of these specimens but the calculated temperatures seemed too warm for the periglacial conditions indicated by approximately coeval dropstones and glendonites unless Permian ocean water δ18O was lighter than ~ -3%. Our Δ47 results also give unrealistically warm winter (~12°C) and summer (~23°C) temperatures for this high-latitude site, raising the possibility

  12. Triple isotope (δD, δ17O, δ18O) study on precipitation, drip water and speleothem fluid inclusions for a Western Central European cave (NW Switzerland)

    NASA Astrophysics Data System (ADS)

    Affolter, Stéphane; Häuselmann, Anamaria D.; Fleitmann, Dominik; Häuselmann, Philipp; Leuenberger, Markus

    2015-11-01

    Deuterium (δD) and oxygen (δ18O) isotopes are powerful tracers of the hydrological cycle and have been extensively used for paleoclimate reconstructions as they can provide information on past precipitation, temperature and atmospheric circulation. More recently, the use of 17Oexcess derived from precise measurement of δ17O and δ18O gives new and additional insights in tracing the hydrological cycle whereas uncertainties surround this proxy. However, 17Oexcess could provide additional information on the atmospheric conditions at the moisture source as well as about fractionations associated with transport and site processes. In this paper we trace water stable isotopes (δD, δ17O and δ18O) along their path from precipitation to cave drip water and finally to speleothem fluid inclusions for Milandre cave in northwestern Switzerland. A two year-long daily resolved precipitation isotope record close to the cave site is compared to collected cave drip water (3 months average resolution) and fluid inclusions of modern and Holocene stalagmites. Amount weighted mean δD, δ18O and δ17O are -71.0‰, -9.9‰, -5.2‰ for precipitation, -60.3‰, -8.7‰, -4.6‰ for cave drip water and -61.3‰, -8.3‰, -4.7‰ for recent fluid inclusions respectively. Second order parameters have also been derived in precipitation and drip water and present similar values with 18 per meg for 17Oexcess whereas d-excess is 1.5‰ more negative in drip water. Furthermore, the atmospheric signal is shifted towards enriched values in the drip water and fluid inclusions (Δ of ˜ + 10‰ for δD). The isotopic composition of cave drip water exhibits a weak seasonal signal which is shifted by around 8-10 months (groundwater residence time) when compared to the precipitation. Moreover, we carried out the first δ17O measurement in speleothem fluid inclusions, as well as the first comparison of the δ17O behaviour from the meteoric water to the fluid inclusions entrapment in speleothems

  13. Measurement of δ18O, δ17O, and 17O-excess in water by off-axis integrated cavity output spectroscopy and isotope ratio mass spectrometry.

    PubMed

    Berman, Elena S F; Levin, Naomi E; Landais, Amaelle; Li, Shuning; Owano, Thomas

    2013-11-01

    Stable isotopes of water have long been used to improve understanding of the hydrological cycle, catchment hydrology, and polar climate. Recently, there has been increasing interest in measurement and use of the less-abundant (17)O isotope in addition to (2)H and (18)O. Off-axis integrated cavity output spectroscopy (OA-ICOS) is demonstrated for accurate and precise measurements δ(18)O, δ(17)O, and (17)O-excess in liquid water. OA-ICOS involves no sample conversion and has a small footprint, allowing measurements to be made by researchers collecting the samples. Repeated (514) high-throughput measurements of the international isotopic reference water standard Greenland Ice Sheet Precipitation (GISP) demonstrate the precision and accuracy of OA-ICOS: δ(18)OVSMOW-SLAP = -24.74 ± 0.07‰ (1σ) and δ(17)OVSMOW-SLAP = -13.12 ± 0.05‰ (1σ). For comparison, the International Atomic Energy Agency (IAEA) value for δ(18)OVSMOW-SLAP is -24.76 ± 0.09‰ (1σ) and an average of previously reported values for δ(17)OVSMOW-SLAP is -13.12 ± 0.06‰ (1σ). Multiple (26) high-precision measurements of GISP provide a (17)O-excessVSMOW-SLAP of 23 ± 10 per meg (1σ); an average of previously reported values for (17)O-excessVSMOW-SLAP is 22 ± 11 per meg (1σ). For all these OA-ICOS measurements, precision can be further enhanced by additional averaging. OA-ICOS measurements were compared with two independent isotope ratio mass spectrometry (IRMS) laboratories and shown to have comparable accuracy and precision as the current fluorination-IRMS techniques in δ(18)O, δ(17)O, and (17)O-excess. The ability to measure accurately δ(18)O, δ(17)O, and (17)O-excess in liquid water inexpensively and without sample conversion is expected to increase vastly the application of δ(17)O and (17)O-excess measurements for scientific understanding of the water cycle, atmospheric convection, and climate modeling among others. PMID:24032448

  14. Assessment of renal function by the stable oxygen and hydrogen isotopes in human blood plasma.

    PubMed

    Kuo, Tai-Chih; Wang, Chung-Ho; Lin, Hsiu-Chen; Lin, Yuan-Hau; Lin, Matthew; Lin, Chun-Mao; Kuo, Hsien-Shou

    2012-01-01

    Water (H(2)O) is the most abundant and important molecule of life. Natural water contains small amount of heavy isotopes. Previously, few animal model studies have shown that the isotopic composition of body water could play important roles in physiology and pathophysiology. Here we study the stable isotopic ratios of hydrogen (δ(2)H) and oxygen (δ(18)O) in human blood plasma. The stable isotopic ratio is defined and determined by δ(sample) = [(R(sample)/R(STD))-1] * 1000, where R is the molar ratio of rare to abundant, for example, (18)O/(16)O. We observe that the δ(2)H and the δ(18)O in human blood plasma are associated with the human renal functions. The water isotope ratios of the δ(2)H and δ(18)O in human blood plasma of the control subjects are comparable to those of the diabetes subjects (with healthy kidney), but are statistically higher than those of the end stage renal disease subjects (p<0.001 for both ANOVA and Student's t-test). In addition, our data indicate the existence of the biological homeostasis of water isotopes in all subjects, except the end stage renal disease subjects under the haemodialysis treatment. Furthermore, the unexpected water contents (δ(2)H and δ(18)O) in blood plasma of body water may shed light on a novel assessment of renal functions.

  15. Stable isotope fractionation during bacterial sulfate reduction is controlled by reoxidation of intermediates

    NASA Astrophysics Data System (ADS)

    Mangalo, Muna; Meckenstock, Rainer U.; Stichler, Willibald; Einsiedl, Florian

    2007-09-01

    Bacterial sulfate reduction is one of the most important respiration processes in anoxic habitats and is often assessed by analyzing the results of stable isotope fractionation. However, stable isotope fractionation is supposed to be influenced by the reduction rate and other parameters, such as temperature. We studied here the mechanistic basics of observed differences in stable isotope fractionation during bacterial sulfate reduction. Batch experiments with four sulfate-reducing strains ( Desulfovibrio desulfuricans, Desulfobacca acetoxidans, Desulfonatronovibrio hydrogenovorans, and strain TRM1) were performed. These microorganisms metabolize different carbon sources (lactate, acetate, formate, and toluene) and showed broad variations in their sulfur isotope enrichment factors. We performed a series of experiments on isotope exchange of 18O between residual sulfate and ambient water. Batch experiments were conducted with 18O-enriched (δ 18O water = +700‰) and depleted water (δ 18O water = -40‰), respectively, and the stable 18O isotope shift in the residual sulfate was followed. For Desulfovibrio desulfuricans and Desulfonatronovibrio hydrogenovorans, which are both characterized by low sulfur isotope fractionation ( ɛS > -13.2‰), δ 18O values in the remaining sulfate increased by only 50‰ during growth when 18O-enriched water was used for the growth medium. In contrast, with Desulfobacca acetoxidans and strain TRM1 ( ɛS < -22.7‰) the residual sulfate showed an increase of the sulfate δ 18O close to the values of the enriched water of +700‰. In the experiments with δ 18O-depleted water, the oxygen isotope values in the residual sulfate stayed fairly constant for strains Desulfovibrio desulfuricans, Desulfobacca acetoxidans and Desulfonatronovibrio hydrogenovorans. However, strain TRM1, which exhibits the lowest sulfur isotope fractionation factor ( ɛS < -38.7‰) showed slightly decreasing δ 18O values. Our results give strong evidence that

  16. Comparing three methods of NEE-flux partitioning from the same grassland ecosystem: the 13C, 18O isotope approach and using simulated Ecosystem respiration

    NASA Astrophysics Data System (ADS)

    Siegwolf, R.; Bantelmann, E.; Saurer, M.; Eugster, W.; Buchmann, N.

    2007-12-01

    As a change in the global climate occurs with increasing temperatures, the Carbon exchange processes of terrestrial ecosystems will change as well. However, it is difficult to quantify the degree to what ecosystem respiration will change relative to the CO2 uptake by photosynthesis. To estimate the carbon sequestration potential of terrestrial vegetation cover it is essential to know both fluxes: ecosystem respiration and the carbon uptake by the vegetation cover. Therefore the net ecosystem exchange of CO2 (NEE) was measured with the eddy covariance method and separated into assimilation and respiration flux. We applied three different approaches, 1) the conventional method, applying the nighttime relationship between soil temperature and NEE for calculating the respiration flux during the day, 2) the use of stable carbon and 3) oxygen isotopes. We compared the results of the three partitioning exercises for a temperate grassland ecosystem in the pre-Alps of Switzerland for four days in June 2004. The assimilation flux derived with the conventional NEE partitioning approach, was best represented at low PAR and low temperatures, in the morning between 5 and 9 am. With increasing temperature and PAR the assimilation for the whole canopy was underestimated. For partitioning NEE via 18O approach, correlations of temperature and radiation with assimilation and respiration flux were significantly higher for the partitioning approach with 18O than for the 13C NEE partitioning. A sensitivity analysis showed the importance of an accurate determination of the equilibrium term θ between CO2 and leaf water δ18O for the NEE partitioning with 18O. For using 13C to partition NEE, the correct magnitude of the 13C fractionation and for the respiration term is essential. The analysis of the data showed that for low light and low morning temperatures the conventional method delivers reasonably good results. When the temperatures exceeded 21°C the isotope approach provided the

  17. An assessment of the isotopic (2H/18O) integrity of water samples collected and stored by unattended precipitation totalizers

    NASA Astrophysics Data System (ADS)

    Terzer, Stefan; Wassenaar, Leonard I.; Douence, Cedric; Araguas-Araguas, Luis

    2016-04-01

    The IAEA-WMO Global Network of Isotopes in Precipitation (GNIP) provides worldwide δ18O and δ2H data for numerous hydrological and climatological studies. The traditional GNIP sample collection method relies on weather station operators to accumulate precipitation obtained from manual rain gauges. Over the past decades, widespread weather station automatization resulted in the increased use of unattended precipitation totalizers that accumulate and store the rainwater in the field for up to one month. Several low-tech measures were adopted to prevent in situ secondary evaporative isotopic enrichment (SEE) of totalized water samples (i.e. disequilibrium isotopic fractionation after precipitation is stored in the collection device). These include: (a) adding a 0.5-1 cm floating layer of paraffin oil to the totalizer bottle, (b) using an intake tube leading from the collection funnel and submerged to the bottom of the totalizer bottle, or (c) placing a table tennis ball in the funnel aiming to reduce evaporation of the collected water from the receiving bottle to the atmosphere. We assessed the isotopic integrity of stored rainwater samples for three totalizers under controlled settings: each aforementioned totalizer was filled with a 100 or 500 mL of isotopically known water and installed in the field with the intake funnels sheltered to prevent rainwater collection. Potential evapotranspiration (PET) was obtained from on-site meteorological recordings. Stored evaporative loss from each totalizer was evaluated on a monthly basis; gravimetrically and by analysing δ18O and δ2H of the stored water, for a period of 6 months and a cumulative PET of ˜500 mm. The gravimetric and isotope results revealed that for smaller water volumes (100 ml, corresponding to ca. 5 mm of monthly precipitation), negligible isotope enrichment (δ18O) was observed in the paraffin-oil based totalizer, whereas unacceptable evaporative isotope effects were observed for the ball

  18. Stable isotope paleoaltimetry: Tectonics and the evolution of landscapes and life

    NASA Astrophysics Data System (ADS)

    Mulch, Andreas

    2015-04-01

    Stable isotope paleoaltimetry exploits systematic changes in the oxygen (δ18O) or hydrogen (δD) isotopic composition of precipitation when lifting of moist air masses over topography induces orographic precipitation. The past 10 years have witnessed rapidly expanding research activities in stable isotope paleoaltimetry that resulted in a broad array of fascinating tectonic studies many of which concentrated on the elevation histories of continental plateau regions. Stable isotope based reconstructions of topography, therefore, have greatly expanded what used to be very sparse global paleoaltimetric information. The topography of mountain ranges and plateaus, however, not only reflects the geodynamic processes that shape the Earth's surface; it also represents a key element in controlling continental moisture transport, atmospheric circulation and the distribution of biomes and biodiversity. The challenge now lies in disentangling the surface uplift component from the inevitable impact of climate change on long-term records of δ18O and δD in precipitation that accompanies surface uplift. The robustness of stable isotope paleoaltimetry reconstructions can be greatly enhanced when high-elevation δ18O or δD proxy data are referenced against low-elevation records that track climate-modulated δ18O or δD of precipitation through time. In addition, evaluating δ18O or δD of precipitation upstream of the orogen/continental plateau region reduces commonly encountered complexities such as topographic threshold conditions to atmospheric circulation, variable moisture recharge to the atmosphere through evapotranspiration over the continents or the impact of hemispheric-scale atmospheric teleconnections; all of which may conspire in setting δ18O or δD of precipitation. Here, I present examples where stable isotope paleoaltimetry data successfully track topographic thresholds to changes in atmospheric circulation and precipitation with a particular focus on the effect

  19. A preliminary multi-stable-isotopic evaluation of three synthetic pathways of Topiramate.

    PubMed

    Jasper, J P; Weaner, L E; Duffy, B J

    2005-09-01

    As a preliminary study of the utility of the natural stable-isotopic differentiation of batch samples produced by different synthetic pathways, multi-stable-isotopic analyses (delta(13)C, delta(15)N, delta(18)O, deltaD) of 53 samples of the antiepileptic drug, Topiramate, produced by three different synthetic pathways (designated "A," "B," "C") were performed. From the outset, we note that there are two fundamental variables that determine the stable-isotopic composition of materials-the stable-isotopic composition of the reagents and starting intermediates, and the isotope fractionation that occurs during manufacture of the product. In this study, the stable-isotopic composition of the raw materials was not controlled and we report here data obtained for a suite of samples that was produced by three synthetic pathways. Graphical examination of these data reveals marked data clustering by synthetic pathway, though in some cases with some overlapping values within standard errors. In general, the isotopic composition of Topiramate from the A and B pathways is distinct from the C pathway. The isotopic data from the A and B pathways typically abut each other, sometimes partially overlapping. The deuterium/hydrogen- (deltaD) and oxygen (delta(18)O) isotopic compositions are each significantly linearly related with the paired carbon (delta(13)C) isotopic composition indicating possible isotopic end-members for the raw materials of the present sample suite. Given that H and O typically derive from meteoric water, the linear correlations with delta(13)C indicate that a mixture of carbon sources (viz., perhaps terrestrial C3 photosynthetic organic carbon and marine C3 organic carbon) were used in the production of the batches tested. If the H and O analyzed were derived from meteoric water, then an elementary comparison of the span of the deltaD (DeltadeltaD = 54.6 +/- 2.1 per thousand) and of the delta(18)O (Deltadelta(18)O = 4.71 +/- 0.26 per thousand) values in the

  20. Water - Isotope - Map (δ 18O, δ 2H, 3H) of Austria: Applications, Extremes and Trends

    NASA Astrophysics Data System (ADS)

    Wyhlidal, Stefan; Kralik, Martin; Benischke, Ralf; Leis, Albrecht; Philippitsch, Rudolf

    2016-04-01

    The isotopic ratios of oxygen and hydrogen in water (2H/1H and 18O/16O) are important tools to characterise waters and their cycles. This starts in the atmosphere as rain or snow and continues in surface water and ends in shallow groundwater as well as in deep groundwater. Tritium formed by natural cosmic radiation in the upper atmosphere and in the last century by tests of thermonuclear bombs in the atmosphere, is characterised by its radioactive decay with a half-life of 12.32 years and is an ideal age-marker during the last 60 years. To determine the origin and mean age of waters in many projects concerning water supply, engineering and scientific projects in the last 45 years on more than 1,350 sites, more than 40,000 isotope measurements were performed in Austria. The median value of all sites of oxygen-18 is δ 18O -10.7 ‰ and for hydrogen-2 δ 2H -75 ‰. As the fractionation is mainly temperature dependent the lowest negative values are observed in winter precipitation (oxygen-18 as low as δ 18O -23 ‰) and in springs in the mountain regions (δ 18O -15.1 ‰). In contrast the highest values were observed in summer precipitation (up to δ 18O - 0.5 ‰) and in shallow lakes in the Seewinkel (up to δ 18O + 5 ‰). The isotopic ratios of the Austrian waters are also influenced by the origin of the evaporated water masses. Therefore the precipitation in the region south of the main Alpine crest (East-Tyrol, Carinthia and South-East Styria) is approximately 1 ‰ higher in δ 18O-values than sites at the same altitude in the northern part. This is most probably caused by the stronger influence of precipitation from the mediterranean area. The median value of all 1,120 sampling sites of decay corrected (2015) tritium measurements is 6.2 tritium units (TU). This is somewhat smaller than the median value of all precipitation stations with 7.2 TU. This can be explained by the fact that in most cases in groundwater the median value has been reduced by decay

  1. Stable isotopes in leaf water of terrestrial plants.

    PubMed

    Cernusak, Lucas A; Barbour, Margaret M; Arndt, Stefan K; Cheesman, Alexander W; English, Nathan B; Feild, Taylor S; Helliker, Brent R; Holloway-Phillips, Meisha M; Holtum, Joseph A M; Kahmen, Ansgar; McInerney, Francesca A; Munksgaard, Niels C; Simonin, Kevin A; Song, Xin; Stuart-Williams, Hilary; West, Jason B; Farquhar, Graham D

    2016-05-01

    Leaf water contains naturally occurring stable isotopes of oxygen and hydrogen in abundances that vary spatially and temporally. When sufficiently understood, these can be harnessed for a wide range of applications. Here, we review the current state of knowledge of stable isotope enrichment of leaf water, and its relevance for isotopic signals incorporated into plant organic matter and atmospheric gases. Models describing evaporative enrichment of leaf water have become increasingly complex over time, reflecting enhanced spatial and temporal resolution. We recommend that practitioners choose a model with a level of complexity suited to their application, and provide guidance. At the same time, there exists some lingering uncertainty about the biophysical processes relevant to patterns of isotopic enrichment in leaf water. An important goal for future research is to link observed variations in isotopic composition to specific anatomical and physiological features of leaves that reflect differences in hydraulic design. New measurement techniques are developing rapidly, enabling determinations of both transpired and leaf water δ(18) O and δ(2) H to be made more easily and at higher temporal resolution than previously possible. We expect these technological advances to spur new developments in our understanding of patterns of stable isotope fractionation in leaf water.

  2. Online Determination of 18O Fractionation Between CO2 and Soil-Water during Soil Dessication by a Novel Mid-Infrared CO2 Isotope Analyzer Coupled to an Dynamic Chamber Incubation System

    NASA Astrophysics Data System (ADS)

    Nowak, A.

    2015-12-01

    The stable oxygen isotope composition of CO2 is an important tracer for quantifying gas interactions between soils and atmosphere. Soils impact atmospheric 18O-CO2 signatures by CO2-H2O equilibration during diffusion of CO2 through the soil column. However, recent research has revealed that also catalytic reactions by carbonic anhydrase, an enzyme used by microorganisms for triggering the conversion of CO2 and water to bicarbonate and protons, is an important factor influencing the oxygen isotopic signature of CO2. In order to study the importance of biotic and abiotic factors for 18O-CO2, we used a novel mid infrared 18O/13C-CO2 analyser coupled to a dynamic chamber system, which allowed us to measure online 18O and 13C of a continuous CO2 stream percolating through soil samples while drying out from fully water saturated to air dry. Our results indicate that changes in CO2- 18O signatures peak at certain soil moistures levels, which is most probably catalysed by the activity of certain microbial groups under optimum growth conditions. More analyses with different soil types and depths, combined with molecular analyses are planned in order to understand the importance of microbial processes and dynamics for influencing soil-CO2 interactions.

  3. Clumped Isotope Verification of δ18O-Based Freshwater Mussel Shell Growth Chronology for a High-Resolution Climate and River Discharge Record

    NASA Astrophysics Data System (ADS)

    VanPlantinga, A.; Grossman, E. L.; Passey, B. H.; Randklev, C.

    2015-12-01

    Isotope profiles in freshwater mussel shells can be used to reconstruct climate, water source, and river discharge, but problems arise from variable water temperature and δ18O. To resolve this complexity and expand the application of isotope sclerochronology to the study of past river systems, we measured δ18O and Δ47 in two common freshwater mussel species from the Brazos River in Texas. To compare the environmental record with the shell record and develop a sclerochronology, weekly water temperature and δ18O data were collected from the Brazos River near College Station from January 2012 to August 2013. The river data reveal complex, irregular patterns for predicted aragonite δ18O. Comparing δ18O profiles from micromilled transects (70-200 µm increments) of coeval shell growth within and between shells yielded consistent patterns. Shell δ18O can be accurately matched to predicted δ18O, providing a chronology of shell growth. However, without a water temperature and δ18O record, interpreting a sclerochronology would be impossible. Shell Δ47 can potentially provide a seasonal chronology to verify the δ18O sclerochronology, which would be invaluable for the use of δ18O sclerochronology in historical and ancient shells. For Δ47 analyses, samples were taken at 0.5 mm resolution in presumed seasonal dark and light growth bands. Clumped temperatures range between 21 and 35 ± 4˚C (Henkes et al., 2013) and track the river temperature record, supporting the interpreted shell δ18O chronology. Shell Δ47-calculated water δ18O values range from -1.2 to 1.5 ± 0.9‰ and match river δ18O. High-resolution shell δ18O profiles combined with Δ47 temperatures can reconstruct a weekly history of water δ18O, and with the observed river discharge vs. water δ18O relation, produce a qualitative record of river discharge. These analytical techniques applied to a historical Brazos River mussel shell collected prior to dam construction reveal weekly records of

  4. Environmental isotopes (18O, 2H, and 87Sr/86Sr) as a tool in groundwater investigations in the Keta Basin, Ghana

    NASA Astrophysics Data System (ADS)

    Jørgensen, Niels; Banoeng-Yakubo, Bruce

    2001-03-01

    Analyses of environmental isotopes (18O, 2H, and 87Sr/86Sr) are applied to groundwater studies with emphasis on saline groundwater in aquifers in the Keta Basin, Ghana. The 87Sr/86Sr ratios of groundwater and surface water of the Keta Basin primarily reflect the geology and the mineralogical composition of the formations in the catchments and recharge areas. The isotopic compositions of 18O and 2H of deep groundwater have small variations and plot close to the global meteoric water line. Shallow groundwater and surface water have considerably larger variations in isotopic compositions, which reflect evaporation and preservation of seasonal fluctuations. A significant excess of chloride in shallow groundwater in comparison to the calculated evaporation loss is the result of a combination of evaporation and marine sources. Groundwaters from deep wells and dug wells in near-coastal aquifers are characterized by relatively high chloride contents, and the significance of marine influence is evidenced by well-defined mixing lines for strontium isotopes, and hydrogen and oxygen stable isotopes, with isotopic compositions of seawater as one end member. The results derived from environmental isotopes in this study demonstrate that a multi-isotope approach is a useful tool to identify the origin and sources of saline groundwater. Résumé. L'analyse des isotopes du milieu (18O, 2H, et 87Sr/86Sr) a été mise en œuvre pour des études hydrogéologiques portant sur des eaux souterraines salées des aquifères du bassin de Keta (Ghana). Les rapports isotopiques 87Sr/86Sr de l'eau souterraine et de l'eau de surface du bassin de Keta reflètent principalement la géologie et la composition minéralogique des formations des bassins d'alimentation et des zones de recharge. Les compositions isotopiques en 18O et en 2H des eaux souterraines profondes présentent de faibles variations et se placent près de la droite des eaux météoriques mondiales. Les eaux des nappes peu profondes

  5. Environmental isotopes (18O, 2H, and 87Sr/86Sr) as a tool in groundwater investigations in the Keta Basin, Ghana

    NASA Astrophysics Data System (ADS)

    Jørgensen, Niels; Banoeng-Yakubo, Bruce

    2001-03-01

    Analyses of environmental isotopes (18O, 2H, and 87Sr/86Sr) are applied to groundwater studies with emphasis on saline groundwater in aquifers in the Keta Basin, Ghana. The 87Sr/86Sr ratios of groundwater and surface water of the Keta Basin primarily reflect the geology and the mineralogical composition of the formations in the catchments and recharge areas. The isotopic compositions of 18O and 2H of deep groundwater have small variations and plot close to the global meteoric water line. Shallow groundwater and surface water have considerably larger variations in isotopic compositions, which reflect evaporation and preservation of seasonal fluctuations. A significant excess of chloride in shallow groundwater in comparison to the calculated evaporation loss is the result of a combination of evaporation and marine sources. Groundwaters from deep wells and dug wells in near-coastal aquifers are characterized by relatively high chloride contents, and the significance of marine influence is evidenced by well-defined mixing lines for strontium isotopes, and hydrogen and oxygen stable isotopes, with isotopic compositions of seawater as one end member. The results derived from environmental isotopes in this study demonstrate that a multi-isotope approach is a useful tool to identify the origin and sources of saline groundwater. Résumé. L'analyse des isotopes du milieu (18O, 2H, et 87Sr/86Sr) a été mise en œuvre pour des études hydrogéologiques portant sur des eaux souterraines salées des aquifères du bassin de Keta (Ghana). Les rapports isotopiques 87Sr/86Sr de l'eau souterraine et de l'eau de surface du bassin de Keta reflètent principalement la géologie et la composition minéralogique des formations des bassins d'alimentation et des zones de recharge. Les compositions isotopiques en 18O et en 2H des eaux souterraines profondes présentent de faibles variations et se placent près de la droite des eaux météoriques mondiales. Les eaux des nappes peu profondes

  6. Stable Isotope Constraints on the Ocean from Hydrothermally-altered Igneous Rocks

    NASA Astrophysics Data System (ADS)

    Gregory, R. T.

    2007-12-01

    The 18O/16O ratio of the ocean provides an important constraint on the global geochemical cycles in the Precambrian Earth. The oxygen isotope ratio of the ocean is most likely buffered near its present day value as long as plate tectonics is operative. A quasi-steady state value for oxygen isotopes is reached on a 100 Myr timescale after the onset of plate tectonics. Hydrothermally-altered igneous rocks constrain the oxygen and hydrogen isotope value of the hydrosphere back through time. Whereas, the oxygen isotope composition of seawater owes its value to the competition between low temperature chemical weathering and mid-ocean ridge hydrothermal exchange, there is no such process for hydrogen isotopes. Changes in the oxygen isotope ratio of seawater should be reflected in hydrothermally altered rocks by the presence of low or high 18O exchanged igneous rocks with normal δD values. The distribution of D and 18O in hydrothermally rocks is used to infer the position of the meteoric water line back through time. Results from the Phanerozoic, the Proterozoic, and the Archean fail to confirm the hypothesis that the global oceans were ever strongly 18O-depleted. The meteoric water line is anchored to the isotopic composition of seawater, the isotope standard for both oxygen and hydrogen isotopes. The ability to use sedimentary rocks or other proxies for climate depend upon the variation in the stable isotopic composition of seawater. Thus far, the hydrothermal record does not support the existence of low 18O oceans. This suggests that low 18O values observed in carbonates and cherts result from either precipitation from oceans with higher temperature or from bodies of water isolated from the open ocean.

  7. Uses of stable isotopes in fish ecology

    EPA Science Inventory

    Analyses of fish tissues (other than otoliths) for stable isotope ratios can provide substantial information on fish ecology, including physiological ecology. Stable isotopes of nitrogen and carbon frequently are used to determine the mix of diet sources for consumers. Stable i...

  8. Novel /sup 18/O kinetic isotope effect in an. cap alpha. -chymotrypsin catalyzed transesterification

    SciTech Connect

    Wang, C.L.A.; Trout, C.M.; Calvo, K.C.; Klapper, M.H.; Wong, L.K.

    1980-01-30

    Reactions were started by injecting the nitrophenyl ester into a stoppered vial immersed in a constant-temperature bath (4/sup 0/C) containing a mixture of /sup 16/O plus /sup 18/O-ethanol, ..cap alpha..-chymotrypsin, and buffer. As the reaction proceeded, samples were withdrawn and injected into a gas chromatograph connected to a quadrupole mass spectrometer controlled by a data acquisition and processing system. The intensities from individual ions were displayed as a function of time to yield chromatographic peaks. Relative /sup 18/O enrichments were computed from the ratios of the peak areas, and the apparent KIE was then calculated from the ratio of enrichments in alcohol and ester. The values of the plateau KIE were less than or equal to 0.90 for all experiments. The apparent first-order rate constant can also be calculated from the magnitude of the initial burst and the slope of the zero-order absorbence increase. This apparent rate constant varies linearly with the ethanol concentration permitting calculation of the second-order rate associated with the formation of the ethyl ester product. 2 figures, 1 table.

  9. Isotopic18O, δD and deuterium excess) records from the TALDICE ice core (East Antarctica) (Invited)

    NASA Astrophysics Data System (ADS)

    Stenni, B.; Buiron, D.; Masson-Delmotte, V.; Bonazza, M.; Braida, M.; Chappellaz, J.; Frezzotti, M.; Falourd, S.; Minster, B.; Selmo, E.

    2010-12-01

    Paleotemperature reconstructions from Antarctic ice cores rely mainly on δD and δ18O records and the main key factors controlling the observed distribution of δD and δ18O in Antarctic surface snow are mainly related to the condensation temperature of the precipitation and the origin of moisture. The deuterium excess, d = δD - 8*δ18O, contains information about climate conditions prevailing in the source regions of precipitation and can be used as an integrated tracer of past hydrological cycle changes. In the framework of the TALos Dome Ice CorE (TALDICE) project, a deep ice core (1620 m) has been drilled at Talos Dome, a peripheral dome of East Antarctica facing the Ross Sea, about 550 km north of Taylor Dome and 1100 km East from the EPICA Dome C drilling site. The TALDICE coring site (159°11'E 72°49'S; 2315 m; T -41°C; www.taldice.org) is located near the dome summit and is characterised by an annual snow accumulation rate of 80 mm water equivalent. Backtrajectory analyses suggest that Talos Dome is mainly influenced by air masses arriving both from the Pacific (Ross Sea) and Indian Ocean sectors. A preliminary dating based on an ice flow model and an inverse method suggests for the upper 1580 m an age of about 300,000 years BP. The full TALDICE δ18O record obtained from the bag samples as well as δD and deuterium excess data are presented here. The δ18O and δD measurements were carried out in Italy and France on a continuous basis of 1 m. These new records will be compared to the ones obtained from the EDC ice core as well as with other East Antarctic ice core records. In particular, we will focus on the whole isotopic profiles, in good agreement with other inland deep ice cores, and on the last deglaciation, showing climatic changes at Talos Dome in phase with the Antarctic plateau and suggesting that the bipolar see saw with Greenland temperature is also valid for this new coastal site facing the Ross Sea sector.

  10. Determining Carbonate Concretion Formation Temperatures and Pore Water δ18O Values Using the Clumped Isotope Approach

    NASA Astrophysics Data System (ADS)

    Loyd, S. J.; Corsetti, F. A.; Tripati, A. K.

    2010-12-01

    The porosity/permeability of siliciclastic strata is affected by post-depositional cementation, but determining at what depth and under what conditions cementation occurs is difficult with standard techniques. The oxygen isotopic composition of solid phase carbonate cements (δ18Ocarb) can be related to temperature (and by extension depth) of formation, and thus has been widely used in diagenetic studies. However, δ18Ocarb paleothermometry requires the prediction or assumption of pore water δ18O (δ18Opw), a parameter that is poorly constrained in past diagenetic environments (for convenience δ18Opw is usually assumed to be 0‰ VSMOW). Here, we use clumped isotope thermometry (CIT)—a fluid δ18O-independent temperature proxy—to avoid the often ambiguous yet necessary δ18Opw assumption applied to δ18Ocarb paleothermometery and reevaluate the temperature of carbonate concretion formation in the Miocene Monterey Formation (dolomite) and the Cretaceous Holz Shale (calcite) of southern California. CIT analysis of Monterey Formation concretions produced slightly increased temperatures of formation versus traditional δ18Ocarb paleothermometry, whereas the Holz Shale concretions produced significantly decreased temperatures. Inputting the CIT-derived temperature into the associated δ18Ocarb-temperature equation allows the calculation of the ancient δ18Opw. Calculated δ18Opw values range from ~ -8 to +2‰ VSMOW, significantly different from coeval seawater. δ18Opw less than 0‰ can be generated by a number of processes including the influx of non-marine fluids and/or hydrate formation, whereas δ18Opw greater than 0‰ can be produced by silicate diagenesis, influx of evaporative brines, or hydrate dissolution. These data demonstrate that pore water modifying diagenetic processes were operating in past environments and emphasize that the formation temperatures of diagenetic carbonates should be calculated using a fluid δ18O-independent approach, such as

  11. Oxygen isotopes in nitrate: New reference materials for 18O:17O:16O measurements and observations on nitrate-water equilibration

    USGS Publications Warehouse

    Böhlke, J.K.; Mroczkowski, S.J.; Coplen, T.B.

    2003-01-01

    Despite a rapidly growing literature on analytical methods and field applications of O isotope-ratio measurements of NO3- in environmental studies, there is evidence that the reported data may not be comparable because reference materials with widely varying ?? 18O values have not been readily available. To address this problem, we prepared large quantities of two nitrate salts with contrasting O isotopic compositions for distribution as reference materials for O isotope-ratio measurements: USGS34 (KNO3) with low ??18O and USGS35 (NaNO3) with high ??18O and 'mass-independent' ??17O. The procedure used to produce USGS34 involved equilibration of HNO3 with 18O-depleted meteoric water. Nitric acid equilibration is proposed as a simple method for producing laboratory NO3- reference materials with a range of ??18O values and normal (mass-dependent) 18O: 17O:16O variation. Preliminary data indicate that the equilibrium O isotope-fractionation factor (??) between [NO 3-] and H2O decreases with increasing temperature from 1.0215 at 22??C to 1.0131 at 100??C. USGS35 was purified from the nitrate ore deposits of the Atacama Desert in Chile and has a high 17O:18O ratio owing to its atmospheric origin. These new reference materials, combined with previously distributed NO3- isotopic reference materials IAEA-N3 (=IAEA-NO-3) and USGS32, can be used to calibrate local laboratory reference materials for determining offset values, scale factors, and mass-independent effects on N and O isotope-ratio measurements in a wide variety of environmental NO 3- samples. Preliminary analyses yield the following results (normalized with respect to VSMOW and SLAP, with reproducibilities of ??0.2-0.3???, 1??): IAEA-N3 has ??18O = +25.6??? and ??17O = +13.2??? USGS32 has ?? 18O = +25.7??? USGS34 has ??18O = -27. 9??? and ??17O = -14.8??? and USGS35 has ?? 18O = +57.5??? and ??17O = +51.5???.

  12. Numerical experiments on the impacts of surface evaporation and fractionation factors on stable isotopes in precipitation

    NASA Astrophysics Data System (ADS)

    Zhang, Xinping; Guan, Huade; Zhang, Xinzhu; Zhang, Wanjun; Yao, Tianci

    2016-06-01

    The isotope enabled atmospheric water balance model is applied to examine the spatial and temporal variations of δ18O in precipitation, amount effect and meteoric water lines (MWL) under four scenarios with different fractionation nature and surface evaporation inputs. The experiments are conducted under the same weather forcing in the framework of the water balance and stable water isotope balance. Globally, the spatial patterns of mean δ18O and global MWLs simulated by four simulation tests are in reasonably good agreement with the Global Network of Isotopes in Precipitation observations. The results indicate that the assumptions of equilibrium fractionation for simulating spatial distribution in mean annual δ18O and the global MWL, and kinetic fractionation in simulating δ18O seasonality are acceptable. In Changsha, four simulation tests all reproduce the observed seasonal variations of δ18O in precipitation. Compared with equilibrium fractionation, the depleted degree of stable isotopes in precipitation is enhanced under kinetic fractionation, in company with a decrease of isotopic seasonality and inter-event variability. The alteration of stable isotopes in precipitation caused by the seasonal variation of stable isotopes in vapour evaporated from the surface is opposite between cold and warm seasons. Four simulations all produce the amount effect commonly observed in monsoon areas. Under kinetic fractionation, the slope of simulated amount effect is closer to the observed one than other scenarios. The MWL for warm and humid climate in monsoon areas are well simulated too. The slopes and intercepts of the simulated MWLs decrease under kinetic fractionation.

  13. Soil phosphate stable oxygen isotopes across rainfall and bedrock gradients.

    PubMed

    Angert, Alon; Weiner, Tal; Mazeh, Shunit; Sternberg, Marcelo

    2012-02-21

    The stable oxygen isotope compositions of soil phosphate (δ(18)O(p)) were suggested recently to be a tracer of phosphorus cycling in soils and plants. Here we present a survey of bioavailable (resin-extractable or resin-P) inorganic phosphate δ(18)O(p) across natural and experimental rainfall gradients, and across soil formed on sedimentary and igneous bedrock. In addition, we analyzed the soil HCl-extractable inorganic δ(18)O(p), which mainly represents calcium-bound inorganic phosphate. The resin-P values were in the range 14.5-21.2‰. A similar range, 15.6-21.3‰, was found for the HCl-extractable inorganic δ(18)O(p), with the exception of samples from a soil of igneous origin that show lower values, 8.2-10.9‰, which indicate that a large fraction of the inorganic phosphate in this soil is still in the form of a primary mineral. The available-P δ(18)O(p) values are considerably higher than the values we calculated for extracellular hydrolysis of organic phosphate, based on the known fractionation from lab experiments. However, these values are close to the values expected for enzymatic-mediated phosphate equilibration with soil-water. The possible processes that can explain this observation are (1) extracellular equilibration of the inorganic phosphate in the soil; (2) fractionations in the soil are different than the ones measured at the lab; (3) effect of fractionation during uptake; and (4) a flux of intercellular-equilibrated inorganic phosphate from the soil microbiota, which is considerably larger than the flux of hydrolyzed organic-P.

  14. Influence of the enzyme dissimilatory sulfite reductase on stable isotope fractionation during sulfate reduction

    NASA Astrophysics Data System (ADS)

    Mangalo, Muna; Einsiedl, Florian; Meckenstock, Rainer U.; Stichler, Willibald

    2008-03-01

    The stable isotopes of sulfate are often used as a tool to assess bacterial sulfate reduction on the macro scale. However, the mechanisms of stable isotope fractionation of sulfur and oxygen at the enzymatic level are not yet fully understood. In batch experiments with water enriched in 18O we investigated the effect of different nitrite concentrations on sulfur isotope fractionation by Desulfovibrio desulfuricans. With increasing nitrite concentrations, we found sulfur isotope enrichment factors ranging from -11.2 ± 1.8‰ to -22.5 ± 3.2‰. Furthermore, the δ18O values in the remaining sulfate increased from approximately 50-120‰ when 18O-enriched water was supplied. Since 18O-exchange with ambient water does not take place in sulfate, but rather in intermediates of the sulfate reduction pathway (e.g. SO32-), we suggest that nitrite affects the steady-state concentration and the extent of reoxidation of the metabolic intermediate sulfite to sulfate during sulfate reduction. Given that nitrite is known to inhibit the production of the enzyme dissimilatory sulfite reductase, our results suggest that the activity of the dissimilatory sulfite reductase regulates the kinetic isotope fractionation of sulfur and oxygen during bacterial sulfate reduction. Our novel results also imply that isotope fractionation during bacterial sulfate reduction strongly depends on the cell internal enzymatic regulation rather than on the physico-chemical features of the individual enzymes.

  15. Stable Carbon and Oxygen Isotope Ratios of Otoliths Differentiate Winter Flounder (Pseudopleuonectes americanus) Habitats

    EPA Science Inventory

    Stable carbon (13C) and oxygen (18O) isotope ratios were measured in otoliths of juvenile winter flounder (Pseudopleuronectes americanus) collected from 18 nursery areas along the coast of Rhode Island, USA. Samples were obtained during June and July of 2002 from locations tha...

  16. 13C and 18O isotopic signatures of CO uptake and release by soil

    NASA Astrophysics Data System (ADS)

    Popa, Maria Elena; Pathirana, Supun L.; Röckmann, Thomas

    2014-05-01

    CO is important for atmospheric chemistry, is a pollutant, and it has been recognized as an important indirect greenhouse gas. Soil uptake is globally one of the main sinks for atmospheric CO. Isotopic measurements can help constraining the global and regional CO budget, but the isotopic signature of the various components of the CO cycle are not all well known. In this study we performed soil chamber experiments in order to determine the isotopic signature of the exchange of CO between soil and atmosphere. We found that the uptake of CO by soil is associated with a small positive fractionation (the lighter CO is taken up faster). In our experiments, even when soil uptake dominated the net flux, a concurrent emission of CO from soil was always present. We were able to determine separately the isotopic effects of the two fluxes, uptake and emission. The isotopic composition of the emitted CO is depleted in 13C compared to atmospheric CO, and compatible with a source from plant and soil organic matter oxidation.

  17. Targeting erythrocyte carbonic anhydrase and 18O-isotope of breath CO2 for sorting out type 1 and type 2 diabetes

    PubMed Central

    Ghosh, Chiranjit; Mandal, Santanu; Banik, Gourab D.; Maity, Abhijit; Mukhopadhyay, Prabuddha; Ghosh, Shibendu; Pradhan, Manik

    2016-01-01

    The inability to envisage the acute onset and progression of type 1 diabetes (T1D) has been a major clinical stumbling block and an important area of biomedical research over the last few decades. Therefore there is a pressing need to develop a new and an effective strategy for early detection of T1D and to precisely distinguish T1D from type 2 diabetes (T2D). Here we describe the precise role of the enzymatic activity of carbonic anhydrase (CA) in erythrocytes in the pathogenesis of T1D and T2D. We show that CA activities are markedly altered during metabolism of T1D and T2D and this facilitates to the oxygen-18 (18O) isotopic fractionations of breath CO2. In our observations, T1D exhibited considerable depletions of 18O-isotopes of CO2, whereas T2D manifested isotopic enrichments of 18O in breath CO2, thus unveiling a missing link of breath18O-isotopic fractionations in T1D and T2D. Our findings suggest that the alterations in erythrocytes CA activities may be the initial step of altered metabolism of T1D and T2D, and breath 18O-isotope regulated by the CA activity is a potential diagnostic biomarker that can selectively and precisely distinguish T1D from T2D and thus may open a potential unifying strategy for treating these diseases. PMID:27767104

  18. The use of δ(2)H and δ(18)O isotopic analyses combined with chemometrics as a traceability tool for the geographical origin of bell peppers.

    PubMed

    de Rijke, E; Schoorl, J C; Cerli, C; Vonhof, H B; Verdegaal, S J A; Vivó-Truyols, G; Lopatka, M; Dekter, R; Bakker, D; Sjerps, M J; Ebskamp, M; de Koster, C G

    2016-08-01

    Two approaches were investigated to discriminate between bell peppers of different geographic origins. Firstly, δ(18)O fruit water and corresponding source water were analyzed and correlated to the regional GNIP (Global Network of Isotopes in Precipitation) values. The water and GNIP data showed good correlation with the pepper data, with constant isotope fractionation of about -4. Secondly, compound-specific stable hydrogen isotope data was used for classification. Using n-alkane fingerprinting data, both linear discriminant analysis (LDA) and a likelihood-based classification, using the kernel-density smoothed data, were developed to discriminate between peppers from different origins. Both methods were evaluated using the δ(2)H values and n-alkanes relative composition as variables. Misclassification rates were calculated using a Monte-Carlo 5-fold cross-validation procedure. Comparable overall classification performance was achieved, however, the two methods showed sensitivity to different samples. The combined values of δ(2)H IRMS, and complimentary information regarding the relative abundance of four main alkanes in bell pepper fruit water, has proven effective for geographic origin discrimination. Evaluation of the rarity of observing particular ranges for these characteristics could be used to make quantitative assertions regarding geographic origin of bell peppers and, therefore, have a role in verifying compliance with labeling of geographical origin.

  19. The use of δ(2)H and δ(18)O isotopic analyses combined with chemometrics as a traceability tool for the geographical origin of bell peppers.

    PubMed

    de Rijke, E; Schoorl, J C; Cerli, C; Vonhof, H B; Verdegaal, S J A; Vivó-Truyols, G; Lopatka, M; Dekter, R; Bakker, D; Sjerps, M J; Ebskamp, M; de Koster, C G

    2016-08-01

    Two approaches were investigated to discriminate between bell peppers of different geographic origins. Firstly, δ(18)O fruit water and corresponding source water were analyzed and correlated to the regional GNIP (Global Network of Isotopes in Precipitation) values. The water and GNIP data showed good correlation with the pepper data, with constant isotope fractionation of about -4. Secondly, compound-specific stable hydrogen isotope data was used for classification. Using n-alkane fingerprinting data, both linear discriminant analysis (LDA) and a likelihood-based classification, using the kernel-density smoothed data, were developed to discriminate between peppers from different origins. Both methods were evaluated using the δ(2)H values and n-alkanes relative composition as variables. Misclassification rates were calculated using a Monte-Carlo 5-fold cross-validation procedure. Comparable overall classification performance was achieved, however, the two methods showed sensitivity to different samples. The combined values of δ(2)H IRMS, and complimentary information regarding the relative abundance of four main alkanes in bell pepper fruit water, has proven effective for geographic origin discrimination. Evaluation of the rarity of observing particular ranges for these characteristics could be used to make quantitative assertions regarding geographic origin of bell peppers and, therefore, have a role in verifying compliance with labeling of geographical origin. PMID:26988484

  20. Application of stable isotopes and hydrochemical analysis in groundwater aquifers of Argolis Peninsula (Greece).

    PubMed

    Matiatos, Ioannis; Alexopoulos, Apostolos

    2011-12-01

    The present study examines the isotopic and hydrochemical composition of 18 inland spring waters and 3 coastal karstic spring waters, covering the period between October 2005 and March 2008. The stable isotopes ((18)O, (2)H) processing has revealed the absence of significant evaporation phenomena and that the origin of fresh water samples is meteoric. Using (18)O values in rainfall waters, an average line of isotopic depletion with altitude has been constructed, extracting a rate of-0.45‰/100 m as typical for the study area. Furthermore, the mean altitude of recharge of the springs has been estimated by plotting the groundwater sampling points on a δ(18)O versus altitude diagram. Hydrochemistry results have shown that the dissolution of carbonate, flysch and ophiolitic formations defines the hydrochemical characteristics of groundwater. Moreover, seawater intrusion in the coastal area is significantly high, causing the water in the three karstic springs to be brackish.

  1. The suitability of the dual isotope approach (δ13C and δ18O) in tree ring studies

    NASA Astrophysics Data System (ADS)

    Siegwolf, Rolf; Saurer, Matthias

    2016-04-01

    The use of stable isotopes, complementary to tree ring width data in tree ring research has proven to be a powerful tool in studying the impact of environmental parameters on tree physiology and growth. These three proxies are thus instrumental for climate reconstruction and improve the understanding of underlying causes of growth changes. In various cases, however, their use suggests non-plausible interpretations. Often the use of one isotope alone does not allow the detection of such "erroneous isotope responses". A careful analysis of these deviating results shows that either the validity of the carbon isotope discrimination concept is no longer true (Farquhar et al. 1982) or the assumptions for the leaf water enrichment model (Cernusak et al., 2003) are violated and thus both fractionation models are not applicable. In this presentation we discuss such cases when the known fractionation concepts fail and do not allow a correct interpretation of the isotope data. With the help of the dual isotope approach (Scheidegger et al.; 2000) it is demonstrated, how to detect and uncover the causes for such anomalous isotope data. The fractionation concepts and their combinations before the background of CO2 and H2O gas exchange are briefly explained and the specific use of the dual isotope approach for tree ring data analyses and interpretations are demonstrated. References: Cernusak, L. A., Arthur, D. J., Pate, J. S. and Farquhar, G. D.: Water relations link carbon and oxygen isotope discrimination to phloem sap sugar concentration in Eucalyptus globules, Plant Physiol., 131, 1544-1554, 2003. Farquhar, G. D., O'Leary, M. H. and Berry, J. A.: On the relationship between carbon isotope discrimination and the intercellular carbon dioxide concentration in leaves, Aust. J. Plant Physiol., 9, 121-137, 1982. Scheidegger, Y., Saurer, M., Bahn, M. and Siegwolf, R.: Linking stable oxygen and carbon isotopes with stomatal conductance and photosynthetic capacity: A conceptual model

  2. Substitution of stable isotopes in Chlorella

    NASA Technical Reports Server (NTRS)

    Flaumenhaft, E.; Katz, J. J.; Uphaus, R. A.

    1969-01-01

    Replacement of biologically important isotopes in the alga Chlorella by corresponding heavier stable isotopes produces increasingly greater deviations from the normal cell size and changes the quality and distribution of certain cellular components. The usefulness of isotopically altered organisms increases interest in the study of such permuted organisms.

  3. The Stable Isotopic Composition of Atmospheric CO2

    NASA Astrophysics Data System (ADS)

    Yakir, D.

    2003-12-01

    in nature ( Thiemens, 1999; see Chapter 4.06, and of triple stable isotopes in geochemistry (e.g., Blunier et al., 2002; Luz et al., 1999; Luz and Barkan, 2000) greatly extended the potential of stable isotope applications.The chemical and isotopic composition of the atmosphere has drawn particular attention in climate-related research both because it is the most accessible component in the tightly coupled land-ocean-atmosphere system, and because the chemical composition of the atmosphere influences climate, particularly via the concentrations of the radiatively active greenhouse gases, such as CO2, O3, CH4, N2O, and water vapor. Information obtained by measurements of the atmospheric concentration of these gases alone is limited; the additional measurements of the stable isotopic composition provide information that cannot be obtained otherwise. Isotopic fractionations during chemical, physical, and biological process in the ocean, land, and the atmosphere result in unique natural labels. Tracing these labels in time and space allows us both to identify specific fluxes of these gases, and to gain insights into the processes influencing the observed fluxes. Quantitative use of 18O and 13C in CO2 must rely on precise observations, on experimentation addressing the isotope effects underlying these observations, and on modeling that tests basic assumptions and extends applications beyond our measuring capabilities. Progress is still needed on all of these fronts. But the importance of this still developing science of stable isotopes in environmental research is indisputable.

  4. Stable Isotope Signatures for Microbial Forensics

    SciTech Connect

    Kreuzer, Helen W.

    2012-01-03

    The isotopic distribution of the atoms composing the molecules of microorganisms is a function of the substrates used by the organisms. The stable isotope content of an organism is fixed so long as no further substrate consumption and biosynthesis occurs, while the radioactive isotopic content decays over time. The distribution of stable isotopes of C, N, O and H in heterotrophic microorganisms is a direct function of the culture medium, and therefore the stable isotope composition can be used to associate samples with potential culture media and also with one another. The 14C content depends upon the 14C content, and therefore the age, of the organic components of the culture medium, as well as on the age of the culture itself. Stable isotope signatures can thus be used for sample matching, to associate cultures with specific growth media, and to predict characteristics of growth media.

  5. Diurnal changes in stable isotopes of leaf water on the southern Tibetan Plateau

    NASA Astrophysics Data System (ADS)

    Yu, Wusheng

    2015-04-01

    Leaf water in plants playing a significant role in the hydrological cycle, will change the existing stable isotope hydrological cycle pattern. Based on stable isotopic analysis and corresponding meteorological measurement, a better understanding of water transport, storage, and usage can be achieved in stable isotope hydrological cycle on the Tibetan Plateau. This study focuses on the diurnal variations of leaf water stable isotopes at the Lhasa station, southern Tibetan Plateau. The results of our data show that, the diurnal variations of stable isotopic compositions (δ18O and δD) of leaf water fluctuate obviously, with high value in the daytime and low value at night. The diurnal fluctuations of deuterium excess (d) of leaf water are also clear, with low value in the daytime and high value at night. At diurnal time scale, both air temperature and relative humidity control the variations of δ18O and δD in leaf water. Relative humidity correlates negatively with δ18O, and positively with d, in contrast to air temperature. The results reveal that deuterium excess may be an indicator of plant transpiration.

  6. Lake Louise Water (USGS47): A new isotopic reference water for stable hydrogen and oxygen isotope measurements

    USGS Publications Warehouse

    Qi, Haiping; Lorenz, Jennifer M.; Coplen, Tyler B.; Tarbox, Lauren V.; Mayer, Bernhard; Taylor, Steve

    2014-01-01

    RESULTS: The δ2H and δ18O values of this reference water are –150.2 ± 0.5 ‰ and –19.80 ± 0.02 ‰, respectively, relative to VSMOW on scales normalized such that the δ2H and δ18O values of SLAP reference water are, respectively, –428 and –55.5 ‰. Each uncertainty is an estimated expanded uncertainty (U = 2uc) about the reference value that provides an interval that has about a 95-percent probability of encompassing the true value. CONCLUSION: This isotopic reference material, designated as USGS47, is intended as one of two isotopic reference waters for daily normalization of stable hydrogen and stable oxygen isotopic analysis of water with a mass spectrometer or a laser absorption spectrometer. "

  7. BOREAS TE-5 CO2 Concentration and Stable Isotope Composition

    NASA Technical Reports Server (NTRS)

    Hall, Forrest G. (Editor); Curd, Shelaine (Editor); Ehleriinger, Jim; Brooks, J. Renee; Flanagan, Larry

    2000-01-01

    The BOREAS TE-5 team collected measurements in the NSA and SSA on gas exchange, gas composition, and tree growth. This data set contains measurements of the concentration and stable carbon (C-13/C-12 and oxygen (O-18/O-16) isotope ratios of atmospheric CO2 in air samples collected at different heights within forest canopies. The data were collected to determine the influence of photosynthesis and respiration by the forest ecosystems on the concentration and stable isotope ratio of atmospheric CO2 These measurements were collected at the SSA during each 1994 IFC at OJP, OBS, and OA sites. Measurements were also collected at the NSA during each 1994 IFC at the OJP, T6R5S TE UBS, and T2Q6A TE OA sites. The stable isotope ratios are expressed using standard delta notation and in units of per mil. The isotope ratios are expressed relative to the international standard, PDB, for both carbon and oxygen samples. The data are stored in tabular ASCII files. The data files are available on a CD-ROM (see document number 20010000884), or from the Oak Ridge National Laboratory (ORNL) Distributed Activity Archive Center (DAAC).

  8. δ 18O(PO 43-) and δ 18O(CO 32-) from belemnite guards from Eastern Europe: implications for palaeoceanographic reconstructions and for the preservation of pristine isotopic values

    NASA Astrophysics Data System (ADS)

    Longinelli, Antonio; Wierzbowski, Hubert; Di Matteo, Antonella

    2003-04-01

    The oxygen isotopic composition of coexisting carbonate and phosphate from belemnite rostra was measured according to well established techniques in 42 samples of Early and Middle Jurassic age and in five samples of oyster shells. Most of the samples come from various locations in the Western Carpathians of Slovakia and Ukraine, and from central Poland. Three samples come from the Isle of Skye. The phosphate content of belemnite rostra, though variable, is systematically very low: consistently lower than about 0.3%. However, this phosphate concentration is close to that found in shells of modern marine organisms including pelecypods, gastropods and Sepia cuttlebones which, in some way, could be considered the modern belemnite counterpart. The measured oxygen isotopic composition of carbonate is within the normal range of values obtained from these fossils ranging from about -1.3 to about +0.6‰ (PDB-1) with the exception of three samples; the δ 13C values range from about -0.8 to about +2.8‰ (PDB-1). With the single exception of one sample from the Isle of Skye, the oxygen isotopic composition of phosphate from belemnite rostra ranges from +19.8 to +24.9‰ (V-SMOW), 22 of the samples measured showing δ 18O values equal to or heavier than +23.0‰. In contrast, the oyster values are considerably lighter, in the case of both carbonate and phosphate. 18O-enriched values can hardly be related to diagenetic processes that normally cause an oxygen isotope shift towards light values. If deposition temperatures are calculated from the heavily enriched values by means of the equation of Longinelli and Nuti [Earth Planet. Sci. Lett. 19 (1973) 373-376] and assuming the δ 18O of Jurassic ocean water to be equal to -1‰ taking into account the lack of ice caps during the Jurassic, the obtained temperatures range from about 8°C to about zero. These temperatures are obviously unreliable when Mesozoic palaeoceanographic conditions and palaeoclimate are taken into account

  9. Isotopic enhancements of 17O and 18O from solar wind particles in the lunar regolith.

    PubMed

    Ireland, Trevor R; Holden, Peter; Norman, Marc D; Clarke, Jodi

    2006-04-01

    Differences in isotopic abundances between meteorites and rocks on Earth leave unclear the true composition of the gas out of which the Solar System formed. The Sun should have preserved in its outer layers the original composition, and recent work has indicated that the solar wind is enriched in 16O, relative to Earth, Mars and bulk meteorites. This suggests that self-shielding of CO due to photo-dissociation, which is a well understood process in molecular clouds, also led to evolution in the isotopic abundances in the early Solar System. Here we report measurements of oxygen isotopic abundances in lunar grains that were recently exposed to the solar wind. We find that 16O is underabundant, opposite to an earlier finding based on studies of ancient metal grains. Our result, however, is more difficult to understand within the context of current models, because there is no clear way to make 16O more abundant in Solar System rocks than in the Sun.

  10. Stable Isotope Systematics in Grasshopper Assemblages Along an Elevation Gradient, Colorado

    NASA Astrophysics Data System (ADS)

    Kohn, M. J.; Evans, S.; Dean, J.; Nufio, C.

    2012-12-01

    Insects comprise over three quarters of all animal species, yet studies of body water isotopic composition are limited to only the cockroach, the hoverfly, and chironomid flies. These studies suggest that oxygen and hydrogen isotopic compositions in body water are primarily controlled by dietary water sources, with modification from respiratory and metabolic processes. In particular, outward diffusion of isotopically depleted water vapor through insect spiracles at low humidity enriches residual body water in 18O and 2H (D). Stable isotope compositions (δ18O and δD) also respond to gradients in elevation and humidity, but these influences remain poorly understood. In this study, we measured grasshopper body water and local vegetation isotopic compositions along an elevation gradient in Colorado to evaluate three hypotheses: 1) Insect body water isotopic composition is directly related to food source water composition 2) Water vapor transport alters body water isotopic compositions relative to original diet sources, and 3) Elevation gradients influence isotopic compositions in insect body water. Thirty-five species of grasshopper were collected from 14 locations in Colorado grasslands, ranging in elevation from 450 to 800 meters (n=131). Body water was distilled from previously frozen grasshopper specimens using a vacuum extraction line, furnaces (90 °C), and liquid nitrogen traps. Water samples were then analyzed for δ18O and δD on an LGR Liquid Water Isotope Analyzer, housed in the Department of Geosciences, Boise State University. Grasshopper body water isotopic compositions show wide variation, with values ranging between -76.64‰ to +42.82‰ in δD and -3.06‰ to +26.78‰ in δ18O. Precipitation δ18O values over the entire Earth excluding the poles vary by approximately 30‰, comparable to the total range measured in our single study area. Most grasshopper values deviate from the global meteoric water line relating δ18O and δD in precipitation

  11. Using water stable isotopes to assess evaporation and water residence time of lakes in EPA’s National Lakes Assessment.

    EPA Science Inventory

    Stable isotopes of water (18O and 2H) can be very useful in large-scale monitoring programs because water samples are easy to collect and water isotopes integrate information about basic hydrological processes such as evaporation as a percentage of inflow (E/I), w...

  12. Spatial and temporal analysis of stable isotopes in tap water across China

    NASA Astrophysics Data System (ADS)

    Zhao, S.; Hu, H.; Tian, F.; Tie, Q.

    2015-12-01

    Stable isotopes in water (δ2H and δ18O) are important indicators of hydrological and ecological pattern and process. Water isotopes have been used to trace atmospheric moisture source, identify source of groundwater and surface water charge, reconstruct paleoclimate, and so on. Tap water appears to reflect pervasive features of regional integrated hydrological process. China is a large-size country with high variations in both environmental and geographical factors including temperature, precipitation amount, relative humidity, latitude, altitude et al. Here we present a first national-scale survey on stable isotope of tap water across China. More than 1000 tap water samples have been collected from 93 cities across China by monthly between December 2014 and November 2015. Stable isotope composition of tap water ranged from -132.1‰ to -25.6‰ (δ2H) and from -17.5‰ to -4.2‰ (δ18O). The Meteoric Water Line is δ2H = 7.77 δ18O + 5.79 (r2 = 0.95) and the LMWL of Chinese precipitation is δ2H =7.6δ18O+ 9.94 (r2= 0.97). Spatial distribution of stable isotopes present typical "continental effect", isotope values generally decrease from coastal regions to inland. Isotopes in different regions present different correlations with temperature, precipitation amount, latitude and altitude as a result of varied moisture source and local water supply. The results of the study could provide mapping information of tap water for fundamental isotope hydrological studies in different regions of China.

  13. [Characteristics of stable isotopes in precipitation over Northeast China and its water vapor sources].

    PubMed

    Li, Xiao-Fei; Zhang, Ming-Jun; Ma, Qian; Li, Ya-Ju; Wang, Sheng-Jie; Wang, Bao-Long

    2012-09-01

    Based on the data of the hydrogen and oxygen stable isotopes in precipitation over Northeast China provided by the Global Network of Isotopes in Precipitation (GNIP) and the meteorological statistics, the spatial and temporal variations of stable isotopes in precipitation and their influencing factors were analyzed and the Local Meteoric Water Line (LMWL) was established. The results were as follows: delta18O value was low in winter and high in summer; the spatial distribution showed that the weighted delta18O value decreased from the south to the north; the linear relationship between delta18O in precipitation and temperature was significant, but no linear relationship was found for the precipitation amount; delta18O in precipitation can be evaluated quantitatively based on a multiple linear regression equation with delta18O and related parameters (temperature, precipitation amount, elevation, longitude and latitude). The water vapor source of the sampling sites was tracked by HYSPLIT 4. 9 model, and the modeled trajectory of vapor source indicated that there were two main paths, including the cold wet water vapor from the Atlantic Ocean and the Arctic Ocean via Westerlies, and the warm one from the Pacific Ocean.

  14. Stable Isotope Enrichment Capabilities at ORNL

    SciTech Connect

    Egle, Brian; Aaron, W Scott; Hart, Kevin J

    2013-01-01

    The Oak Ridge National Laboratory (ORNL) and the US Department of Energy Nuclear Physics Program have built a high-resolution Electromagnetic Isotope Separator (EMIS) as a prototype for reestablishing a US based enrichment capability for stable isotopes. ORNL has over 60 years of experience providing enriched stable isotopes and related technical services to the international accelerator target community, as well as medical, research, industrial, national security, and other communities. ORNL is investigating the combined use of electromagnetic and gas centrifuge isotope separation technologies to provide research quantities (milligram to several kilograms) of enriched stable isotopes. In preparation for implementing a larger scale production facility, a 10 mA high-resolution EMIS prototype has been built and tested. Initial testing of the device has simultaneously collected greater than 98% enriched samples of all the molybdenum isotopes from natural abundance feedstock.

  15. North American precipitation isotope18O) zones revealed in time series modeling across Canada and northern United States

    NASA Astrophysics Data System (ADS)

    Delavau, C.; Chun, K. P.; Stadnyk, T.; Birks, S. J.; Welker, J. M.

    2015-02-01

    Delineating spatial patterns of precipitation isotopes ("isoscapes") is becoming increasingly important to understand the processes governing the modern water isotope cycle and their application to migration forensics, climate proxy interpretation, and ecohydrology of terrestrial systems. However, the extent to which these patterns can be empirically predicted across Canada and the northern United States has not been fully articulated, in part due to a lack of time series precipitation isotope data for major regions of North America. In this study, we use multiple linear regressions of CNIP, GNIP, and USNIP observations alongside climatological variables, teleconnection indices, and geographic indicators to create empirical models that predict the δ18O of monthly precipitation (δ18Oppt) across Canada and the northern United States. Five regionalization approaches are used to separate the study domain into isotope zones to explore the effect of spatial grouping on model performance. Stepwise regression-derived parameterizations quantified by permutation testing indicate the significance of precipitable water content and latitude as predictor variables. Within the Canadian Arctic and eastern portion of the study domain, models from all regionalizations capture the interannual and intraannual variability of δ18Oppt. The Pacific coast and northwestern portions of the study domain show less agreement between models and poorer model performance, resulting in higher uncertainty in simulations throughout these regions. Long-term annual average δ18Oppt isoscapes are generated, highlighting the uncertainty in the regionalization approach as it compounds over time. Additionally, monthly time series simulations are presented at various locations, and model structure uncertainty and 90% bootstrapped prediction bounds are detailed for these predictions.

  16. Effect of 2H and 18O water isotopes in kinesin-1 gliding assay

    PubMed Central

    Herskowitz, Lawrence J.; Koch, Steven J.

    2014-01-01

    We show for the first time the effects of heavy-hydrogen water (2H2O) and heavy-oxygen water (H218O) on the gliding speed of microtubules on kinesin-1 coated surfaces. Increased fractions of isotopic waters used in the motility solution decreased the gliding speed of microtubules by a maximum of 21% for heavy-hydrogen and 5% for heavy-oxygen water. We also show that gliding microtubule speed returns to its original speed after being treated with heavy-hydrogen water. We discuss possible interpretations of these results and the importance for future studies of water effects on kinesin and microtubules. We also discuss the implication for using heavy waters in biomolecular devices incorporating molecular motors. PMID:24711961

  17. Stable isotope labeling methods for DNA.

    PubMed

    Nelissen, Frank H T; Tessari, Marco; Wijmenga, Sybren S; Heus, Hans A

    2016-08-01

    NMR is a powerful method for studying proteins and nucleic acids in solution. The study of nucleic acids by NMR is far more challenging than for proteins, which is mainly due to the limited number of building blocks and unfavorable spectral properties. For NMR studies of DNA molecules, (site specific) isotope enrichment is required to facilitate specific NMR experiments and applications. Here, we provide a comprehensive review of isotope-labeling strategies for obtaining stable isotope labeled DNA as well as specifically stable isotope labeled building blocks required for enzymatic DNA synthesis. PMID:27573183

  18. Water budget determination for Northern groundwater dependent lakes using stable isotopes of water

    NASA Astrophysics Data System (ADS)

    Isokangas, Elina; Rossi, Pekka; Ronkanen, Anna-Kaisa; Kløve, Bjørn

    2013-04-01

    Understanding groundwater - surface water interaction is crucial in numerous water resources management problems. Stable isotopes of water can bring understanding of this interaction especially in catchment scale questions. In this study stable isotopes were used in a Finnish esker aquifer (Lat 64.58° , Lon 26.50° ) where groundwater dependent lakes have suffered from seasonal water level declines. Esker aquifers are the main groundwater reserves in Finland used in water abstraction. In order to determine how hydrology of the lakes is dependent on groundwater, the isotopic composition of oxygen and hydrogen was studied from 36 sampling points during years 2010 to 2012. Samples were taken from 13 groundwater pipes, 11 lakes and 11 streams during winter, spring, summer and autumn. Additionally local precipitation was sampled. The CRDS-method (Picarro L2120-i analyzer) was used to analyze δ18O- and δ2H-values. The data from the study was used to define the Local Meteoric Water Line of the site (δ2H = 7.60 δ18O + 6.70) and the groundwater line of the esker aquifer (δ2H = 7.59 δ18O + 4.79). The groundwater line of the esker aquifer differs from the groundwater line of Finnish groundwaters (δ2H = 8.51 δ18O + 16.65) based on previous studies. This emphasizes the importance of using local isotopic values when stable isotopes of water are used in hydrological studies. Furthermore, the isotopic compositions of the examined lakes differed enough from the isotopic composition of the local groundwater to separate groundwater component in the lake hydrology. The results also verified that evaporation from lakes in Northern Finland can be high enough to utilize isotopic method for determination of groundwater and surface water interactions.

  19. [Monitoring and Analysis of Stable Isotopes of the Near Surface Water Vapor in Changsha].

    PubMed

    Xie, Yu-long; Zhang, Xin-ping; Yao, Tian-ci; Huang, Huang

    2016-02-15

    Based on the monitored atmospheric water vapor stable isotopes and observed meteorological elements at Changsha during the period from November 12, 2014 to April 13, 2015, the variations of water vapor stable isotopes and the relationships between isotope ratios and temperature, absolute humidity, precipitation amount were analyzed in this paper. The results indicated that: (1) Seasonal variations of delta18O and 82H in atmospheric water vapor at Changsha were remarkable, with high values in winter. delta18O and delta2H in atmospheric water vapor were positively correlated with absolute humidity in winter. There were some fluctuations of the delta18O and delta2H in atmospheric water vapor, especially when the precipitation events occurred. Precipitation events had a significant effect on the variations of delta18O and delta2H in atmospheric water vapor, and low values were often accompanied with precipitation events; (2) Diurnal Variations of delta18O and delta2H in atmospheric water vapor had a close correlation with the atmospheric water vapor content, whereas the absolute humidity was mainly controlled by the strength of the local evapotranspiration and atmospheric turbulence. The "precipitation amount effect" was observed during the process of a single precipitation event; (3) Values of delta18O and delta2H in atmospheric water vapor were always lower than those of precipitation in Changsha, but he variation trends were completely consistent, the average difference values were 8.6% per hundred and 66.82% per hundred, respectively; (4) The meteoric vapor line (MVL) in cold months was delta2H =7.18 delta18O + 10.58, the slope and intercept of MVL were always lower than those of MWL, and the slope and intercept of MVL in spring were significantly higher than those of winter. PMID:27363133

  20. Stable Isotope Mapping of Alaskan Grasses and Marijuana

    NASA Astrophysics Data System (ADS)

    Booth, A. L.; Wooller, M. J.

    2008-12-01

    The spatial variation of isotope signatures in organic material is a useful forensic tool, particularly when applied to the task of tracking the production and distribution of plant-derived illicit drugs. In order to identify the likely grow-locations of drugs such as marijuana from unknown locations (i.e., confiscated during trafficking), base isotope maps are needed that include measurements of plants from known grow-locations. This task is logistically challenging in remote, large regions such as Alaska. We are therefore investigating the potential of supplementing our base (marijuana) isotope maps with data derived from other plants from known locations and with greater spatial coverage in Alaska. These currently include >150 samples of modern C3 grasses (Poaceae) as well as marijuana samples (n = 18) from known grow-locations across the state. We conducted oxygen, carbon and nitrogen stable isotope analyses of marijuana and grasses (Poaceae). Poaceae samples were obtained from the University of Alaska Fairbanks (UAF) Museum of the North herbarium collection, originally collected by field botanists from around Alaska. Results indicate that the oxygen isotopic composition of these grasses range from 10‰ to 30‰, and broadly mirror the spatial pattern of water isotopes in Alaska. Our marijuana samples were confiscated around the state of Alaska and supplied to us by the UAF Police Department. δ13C, δ15N and δ18O values exhibit geographic patterns similar to the modern grasses, but carbon and nitrogen isotopes of some marijuana plants appear to be influenced by additional factors related to indoor growing conditions (supplementary CO2 sources and the application of organic fertilizer). As well as providing a potential forensic resource, our Poaceae isotope maps could serve additional value by providing resources for studying ecosystem nutrient cycling, for tracing natural ecological processes (i.e., animal migration and food web dynamics) and providing

  1. Estimation of evapotranspiration rate in irrigated lands using stable isotopes

    NASA Astrophysics Data System (ADS)

    Umirzakov, Gulomjon; Windhorst, David; Forkutsa, Irina; Brauer, Lutz; Frede, Hans-Georg

    2013-04-01

    Agriculture in the Aral Sea basin is the main consumer of water resources and due to the current agricultural management practices inefficient water usage causes huge losses of freshwater resources. There is huge potential to save water resources in order to reach a more efficient water use in irrigated areas. Therefore, research is required to reveal the mechanisms of hydrological fluxes in irrigated areas. This paper focuses on estimation of evapotranspiration which is one of the crucial components in the water balance of irrigated lands. Our main objective is to estimate the rate of evapotranspiration on irrigated lands and partitioning of evaporation into transpiration using stable isotopes measurements. Experiments has done in 2 different soil types (sandy and sandy loam) irrigated areas in Ferghana Valley (Uzbekistan). Soil samples were collected during the vegetation period. The soil water from these samples was extracted via a cryogenic extraction method and analyzed for the isotopic ratio of the water isotopes (2H and 18O) based on a laser spectroscopy method (DLT 100, Los Gatos USA). Evapotranspiration rates were estimated with Isotope Mass Balance method. The results of evapotranspiration obtained using isotope mass balance method is compared with the results of Catchment Modeling Framework -1D model results which has done in the same area and the same time.

  2. Down Core Oxygen Isotopic Measurements Of Diatom δ18O From The Guaymas Basin, Gulf Of California

    NASA Astrophysics Data System (ADS)

    Menicucci, A. J.; Spero, H. J.; Thunell, R.

    2015-12-01

    The Guaymas Basin (GB), Gulf of California (27º53'N, 111º40'W ), is an evaporative basin, with sea surface temperatures (SST) varying between ~30oC (summer) and ~15oC (winter). Productivity is controlled mostly by seasonal upwelling starting in fall (early November) and extending into spring. We are currently analyzing δ18Odiatom from a boxcore (BC-43) using microfluorination (Menicucci, et al. 2013). This boxcore was previously analyzed for UK '37 alkenones and 210Pb activity (Goni, et al. 2001). Residual BC-43 material was sampled at ~2cm intervals. Samples were cleaned to isolate diatoms from other sediments, then equilibrated in water with δ18Owater = +85‰ for 70 hours at 21oC prior to vacuum dehydroxylation and microfluorination. The latter equilibration was done to account for fractionation between covalently bound O and OH- groups during vacuum dehydroxylation, preserving the original δ18Odiatom value. We present δ18Odiatom data from BC-43 samples covering 27cm, equivalent to >225 years of sediment accumulation. δ18O data are converted to temperature (T) based on an existing calibration (Leclerc and Labeyrie 1987). Our data suggest δ18Odiatom values record a T range of 22-18oC, corresponding to the mixed layer depth and the chlorophyll maximum during the fall bloom. These T values are offset from SST data by a mean of 5oC for the same sample intervals. However, δ18Odiatom values from the most recent samples suggest a ~2oC increase in diatom T relative to SST during the last 35 years. This subsurface warming may be due to decreased fall upwelling, increased mixed layer and chlorophyll maximum depths, and/or the timing of the peak diatom bloom. Such correlations are being investigated and the latest results will be presented. Goni, M. A., et al. (2001). Oceanographic considerations for the application of the alkenone-based paleotemperature U-37(K ') index in the Gulf of California. Geochimica Et Cosmochimica Acta 65: 545-557. Leclerc, A. J. and L

  3. Stable Isotopic Constraints of the Turpan Basin in Northwestern China

    NASA Astrophysics Data System (ADS)

    Schaen, A. J.

    2010-12-01

    Stable isotopic analysis of sedimentary rocks can be used to reconstruct past geologic changes in the elevation and climate of topographic features such as mountain ranges and plateaus. The Tibetan Plateau is an ideal field laboratory for conducting this type of study because of the Plateau’s extreme topographic relief and relatively recent geologic growth. Here we present oxygen and carbon isotope compositions from a suite of sedimentary rock samples taken from the western Turpan Basin in northwestern China. This area of the basin collects sediment from weathering and erosion of the Bogda Shan located to the north. The goal of this study is to analyze changes in the stable isotope composition as a function of stratigraphic position to reconstruct paleoelevations and paleoclimates in this part of the Tibetan Plateau. The sedimentary rock samples analyzed in this study are Late Jurassic to Neogene age and are primarily mudstone, siltstone, fine sandstone along with lesser limestone. Samples were powered and then dissolved with phosphoric acid at 72οC. The liberated CO2 gas was then analyzed using a Finnigan Delta Plus XL mass spectrometer with a gasbench inlet system. Oxygen isotope values range from -13.72 to -1.62‰ (PDB) and exhibit a large scale trend to more negative values toward the top of the stratigraphic sequence. Superimposed on this large scale trend are systematic variations in isotopic composition as a function of age. The most positive δ18O values occur at approximately 160, 115, 60, and 5 ma. Conversely, δ18O minima are observed at 150, 90, and 40 ma. δ13C values range from -10.69‰ to 1.40‰ (PDB). The most positive δ13C values (-4.3 to 1.4) occur from 120-160 ma. Younger samples display small scale variations with age with notable δ13C minima of -10.7, -14.7, and -7.6‰ at 108, 80, and 17 ma, respectively. The variable δ18O and positive δ13C values from the Jurassic (145-160 ma) are consistent with an arid climate and high atmospheric

  4. Patterns of mortality among South Florida Manatees: Evidence from oxygen, sulfur and deuterium stable isotopes

    NASA Astrophysics Data System (ADS)

    MacAvoy, S. E.; Bacalan, V.; Kazantseva, M.; Rhodes, J.; Kim, K.

    2012-12-01

    The Florida manatee (Trichechus manatus latirostris) is an endangered marine mammal whose coastal habitat has been heavily altered by human development. Sources of mortality include anthropogenic and environmental causes. Necropsies were completed on 75 deceased individuals, and tissues, including bone samples, were collected for later analysis. This study investigates the utility of manatee bone stable oxygen (δ18O), sulfur (δ34S) and deuterium (δD) for determining where the animals lived (which may not be where they where their bodies were recovered), and the relative importance of marine versus freshwater for the individual animals. The isotopes can provide a "geochemical map" showing the distribution of mortality, aiding in the evaluation of geographical patterns in mortality. The δ18O signatures of the bones ranged from 14 to 18.5‰, with no significant difference between male and female mean values. δ18O significantly decreased with increasing latitude (p=.0016), a trend positively correlated with coastal Florida seawater δ18O literature values obtained from the NASA Global Seawater Oxygen-18 Database (http://data.giss.nasa.gov/o18data/) and the EAIA stable isotope database (http://www.univie.ac.at/cartography/project/wiser/). Bone δ34S indicated the influence of marine versus coastal freshwater dietary sources on the animals. Most individuals showed 34S-depleted signatures, which indicated a non-marine sulfur source; however some individuals clearly had taken up marine sulfate (mean 4.9 ± 3.7‰, range 0.8 to 13.8‰). Deuterium values were not available at the time this abstract was written, however we hypothesize that those values will co-vary with δ18O. We conclude that manatee diets are based on both marine and freshwater sources, but freshwater sources exert more influence. Marine water and manatee δ18O co-vary with latitude, suggesting that stable oxygen isotopes may be useful indicators of the latitude where manatees lived.

  5. [Review of dual stable isotope technique for nitrate source identification in surface- and groundwater in China].

    PubMed

    Xu, Zhi-Wei; Zhang, Xin-Yu; Yu, Gui-Rui; Sun, Xiao-Min; Wen, Xue-Fa

    2014-08-01

    Water nitrate (NO3-) contamination is a world-wide environmental problem under the effects of intensive human activities. Sources identification of NO3- contamination in water is important for better management of water quality. Dual stable isotope data of nitrate nitrogen (delta15N) and nitrate oxygen (delta18O) combined with other stable isotopes and chemical analysis data have been frequently used to identify NO3- sources, differentiate percentage of the different NO3- sources and assess the nitrification/denitrification processes of surface water, groundwater and precipitation, respectively. This review summarized the analysis technique of nitrate delta15N and delta18O in domestic and abroad, assessed typical values of delta15N, delta18O from different NO3- sources and evaluated the progress in application of dual stable isotope of delta15N and delta18O technique to trace NO3- sources in surface- and ground-water. Both ion exchange-AgNO3 and bacteria denitrifying methods have been successfully used in tracing water nitrate sources nationwide. The comprehensive metadata analysis of nitrate sources showed that the delta15N values of sewage and manure, soil, precipitation, fertilizer ranged from 3 per thousand to 17 per thousand, 3 per thousand to 8 per thousand, - 9 per thousand to 9 per thousand, -2 per thousand to 4 per thousand, respectively. And the delta15N values of ammonium fertilizer ranged from - 4 per thousand to 2 per thousand. According to the stable isotope technique, sewage and manure were identified as the major nitrate sources of surface- and ground-water in China. This indicated that municipal sewage and aquaculture exerted serious influence on the nitrate pollution of surface water. In the future, long-term monitoring, dual stable isotope fingerprinting and hydro-chemical analysis should be applied together to quantitatively differentiate contribution of nitrate sources, and to assess seasonal dynamic of nitrate sources. It will provide useful

  6. Precipitation regime and stable isotopes at Dome Fuji, East Antarctica

    NASA Astrophysics Data System (ADS)

    Dittmann, Anna; Schlosser, Elisabeth; Masson-Delmotte, Valérie; Powers, Jordan G.; Manning, Kevin W.; Werner, Martin; Fujita, Koji

    2016-06-01

    A unique set of 1-year precipitation and stable water isotope measurements from the Japanese Antarctic station, Dome Fuji, has been used to study the impact of the synoptic situation and the precipitation origin on the isotopic composition of precipitation on the Antarctic Plateau. The Antarctic Mesoscale Prediction System (AMPS) archive data are used to analyse the synoptic situations that cause precipitation. These situations are investigated and divided into five categories. The most common weather situation during a precipitation event is an upper-level ridge that extends onto the Antarctic Plateau and causes strong northerly advection from the ocean. Most precipitation events are associated with an increase in temperature and wind speed, and a local maximum of δ18O. During the measurement period, 21 synoptically caused precipitation events caused 60 % of the total annual precipitation, whereas the remaining 40 % were predominantly attributed to diamond dust. By combining the synoptic analyses with 5-day back-trajectories, the moisture source regions for precipitation events were estimated. An average source region around a latitude of 55° S was found. The atmospheric conditions in the source region were used as initial conditions for running a Rayleigh-type isotopic model in order to reproduce the measured isotopic composition of fresh snow and to investigate the influence of the precipitation source region on the isotope ratios. The model represents the measured annual cycle of δ18O and the second-order isotopic parameter deuterium excess reasonably well, but yields on average too little fractionation along the transport/cooling path. While simulations with an isotopic general circulation model (GCM) (ECHAM5-wiso) for Dome Fuji are on average closer to the observations, this model cannot reproduce the annual cycle of deuterium excess. In the event-based analysis, no evidence of a correlation of the measured deuterium excess with the latitude of the

  7. The effect of carbonic anhydrase on the kinetics and equilibrium of the oxygen isotope exchange in the CO2-H2O system: Implications for δ18O vital effects in biogenic carbonates

    NASA Astrophysics Data System (ADS)

    Uchikawa, Joji; Zeebe, Richard E.

    2012-10-01

    Interpretations of the primary paleoceanographic information recorded in stable oxygen isotope values (δ18O) of biogenic CaCO3 can be obscured by disequilibrium effects. CaCO3 is often depleted in 18O relative to the δ18O values expected for precipitation in thermodynamic equilibrium with ambient seawater as a result of vital effects. Vital effects in δ18O have been explained in terms of the influence of fluid pH on the overall δ18O of the sum of dissolved inorganic carbon (DIC) species (often referred to as "pH model") and in terms of 18O depletion as a result of the kinetic effects associated with CO2 hydration (CO2 + H2O ↔ H2CO3 ↔ HCO3- + H+) and CO2 hydroxylation (CO2 + OH- ↔ HCO3-) in the calcification sites (so-called "kinetic model"). This study addresses the potential role of an enzyme, carbonic anhydrase (CA), that catalyzes inter-conversion of CO2 and HCO3- in relation to the underlying mechanism of vital effects. We performed quantitative inorganic carbonate precipitation experiments in order to examine the changes in 18O equilibration rate as a function of CA concentration. Experiments were performed at pH 8.3 and 8.9. These pH values are comparable to the average surface ocean pH and elevated pH levels observed in the calcification sites of some coral and foraminiferal species, respectively. The rate of uncatalyzed 18O exchange in the CO2-H2O system is governed by the pH-dependent DIC speciation and the kinetic rate constant for CO2 hydration and hydroxylation, which can be summarized by a simple mathematical expression. The results from control experiments (no CA addition) are in agreement with this expression. The results from control experiments also suggest that the most recently published kinetic rate constant for CO2 hydroxylation has been overestimated. When CA is present, the 18O equilibration process is greatly enhanced at both pH levels due to the catalysis of CO2 hydration by the enzyme. For example, the time required for 18O

  8. Illuminating hydrological processes at the soil-vegetation-atmosphere interface with water stable isotopes

    NASA Astrophysics Data System (ADS)

    Sprenger, Matthias; Leistert, Hannes; Gimbel, Katharina; Weiler, Markus

    2016-09-01

    Water stable isotopes (18O and 2H) are widely used as ideal tracers to track water through the soil and to separate evaporation from transpiration. Due to the technical developments in the last two decades, soil water stable isotope data have become easier to collect. Thus, the application of isotope methods in soils is growing rapidly. Studies that make use of soil water stable isotopes often have a multidisciplinary character since an interplay of processes that take place in the vadose zone has to be considered. In this review, we provide an overview of the hydrological processes that alter the soil water stable isotopic composition and present studies utilizing pore water stable isotopes. The processes that are discussed include the water input as precipitation or throughfall, the output as evaporation, transpiration, or recharge, and specific flow and transport processes. Based on the review and supported by additional data and modeling results, we pose a different view on the recently proposed two water world hypothesis. As an alternative to two distinct pools of soil water, where one pool is enriched in heavy isotopes and used by the vegetation and the other pool does not undergo isotopic fractionation and becomes recharge, the water gets successively mixed with newly introduced rainwater during the percolation process. This way, water initially isotopically enriched in the topsoil loses the fractionation signal with increasing infiltration depth, leading to unfractionated isotopic signals in the groundwater.

  9. [Variations and simulation of stable isotopes in precipitation in the Heihe River basin].

    PubMed

    Wu, Jin-Kui; Yang, Qi-Yue; Ding, Yong-Jian; Ye, Bai-Sheng; Zhang, Ming-Quan

    2011-07-01

    To study the variations of deltaD and delta18O in precipitation, 301 samples were sampled during 2002-2004 in 6 sites in the Heihe River basin, Northwestern China. The deltaD and delta18O values ranged from 59 per thousand to -254 per thousand and 6.5 per thousand to -33.4 per thousand, respectively. This wide range indicated that stable isotopes in precipitation were controlled by different condensation mechanisms as a function of air temperature and varying sources of moisture. delta18O in precipitation had a close positive relationship with the air temperature, i. e., a clear temperature effect existed in this area. At a monthly scale, no precipitation effect existed. On the other hand, a weak precipitation effect still accrued at precipitation events scale. The spatial variation of delta18O showed that the weighted average delta18O values decreased with the increasing altitude of sampling sites at a gradient of -0. 47 per thousand/100m. A regional Meteoric Water Line, deltaD = 7.82 delta18O + 7.63, was nearly identical to the Meteoric Water Line in the Northern China. The results of backward trajectory of each precipitation day at Xishui showed that the moisture of the precipitation in cold season (October to March) mainly originated from the west while the moisture source was more complicated in warm season (April to September). The simulation of seasonal delta18O variation showed that the stable isotope composition of precipitation tended to a clear sine-wave seasonal variation. PMID:21922801

  10. The Po river water from the Alps to the Adriatic Sea (Italy): new insights from geochemical and isotopic (δ(18)O-δD) data.

    PubMed

    Marchina, Chiara; Bianchini, Gianluca; Natali, Claudio; Pennisi, Maddalena; Colombani, Nicolò; Tassinari, Renzo; Knoeller, Kay

    2015-04-01

    Although the Po river is the most important fluvial system of Northern Italy, the systematic geochemical and isotopic investigations of its water are rare and were never reported for the whole basin. The present contribution aims to fill this knowledge gap, reporting a comprehensive data set including oxygen and hydrogen stable isotopes as well as major and trace element concentration of dissolved species for 54 Po river water samples, mainly collected in different hydrological conditions (peak discharge in April, drought in August) at increasing distance from the source, i.e., from the upper part of the catchment to the terminal (deltaic) part of the river at the confluence with the Adriatic Sea. The isotopic compositions demonstrate that the predominant part of the runoff derives from the Alpine sector of the catchment through important tributaries such as the Dora Baltea, Ticino, Adda, and Tanaro rivers, whereas the contribution from the Apennines tributaries is less important. The geochemical and isotopic compositions show that the Po river water attains a homogeneous composition at ca. 100 km from the source. The average composition is characterized by δ(18)O -9.8‰, δD -66.2‰, total dissolved solid (TDS) 268 mg/L, and chloride 17 mg/L and by a general Ca-HCO3 hydrochemical facies, which is maintained for most of the river stream, only varying in the terminal part where the river is diverted in a complex deltaic system affected by more significant evaporation and mixing with saline water evidenced by higher TDS and chloride content (up to 8198 and 4197 mg/L, respectively). Geochemical and isotopic maps have been drawn to visualize spatial gradients, which reflect the evolution of the river water composition at progressive distance from the source; more detailed maps were focused on the deltaic part in order to visualize the processes occurring in the transitional zone toward the Adriatic Sea. The data also highlight anthropogenic contributions, mainly

  11. Evaluation of Stable Isotope Analysis as a Tool to Determine Nitrate Sources in Irish Groundwaters

    NASA Astrophysics Data System (ADS)

    Minet, E.; Coxon, C.; Kalin, R.

    2004-12-01

    Natural abundance of stable isotope ratios of nitrogen (\\delta15N) and oxygen (\\delta18O) in NO3 were measured in a nitrate-vulnerable aquifer in eastern Ireland underlying an intensive agricultural area. The aim was to determine whether the dual stable isotope approach (\\delta15N and \\delta18O) could provide a more power tool than \\delta15N measurements alone for determining the source of groundwater nitrate. Forty-five private wells and boreholes representing a range of potential N sources (diffuse sources such as synthetic fertiliser spreading and/or farmyard effluents and/or septic tank effluents) were sampled on seven occasions between 2002 and 2004. Additionally, nitrate leachate samples were collected from the unsaturated zone under small-scale experiments simulating different agricultural practices. Nitrate was extracted from each water sample using an anion exchange resin technique (Silva et al., 2000), and \\delta15N and \\delta18O values were both measured by Continuous-Flow Isotopic Ratio Mass Spectrometry. The initial hypothesis was that, in a shallow gravel aquifer where nitrate leaching is important and fast, groundwater nitrates are likely to display the isotopic characteristics of their source (low \\delta15N and high \\delta18O for diffuse sources, compared to high \\delta15N and low \\delta18O for point sources). The first set of results indicates that the \\delta15N values only follow this trend, although the \\delta18O values suggest the occurrence of denitrification. The levelling of \\delta18O values may in fact be caused by the Mineralisation-Immobilisation Turnover processes (MIT) that have previously been found to occur in the unsaturated zone, incorporating new oxygen atoms during the remineralisation of the nitrate (Mengis et al., 2001). References Mengis, M.; Walther, U.; Bernasconi, S.M.; Wehrli, B. (2001) Limitations of using \\delta18O for the source identification of nitrate in agricultural soils. Environmental Science

  12. Stable isotope ecology in the Ituri Forest.

    PubMed

    Cerling, Thure E; Hart, John A; Hart, Terese B

    2004-01-01

    The Ituri Forest, Democratic Republic of Congo (formerly Zaire) is an example of a closed canopy forest showing extreme depletion in (13)C. delta(13)C values for plants from the canopy top, from gaps in the canopy, and from the subcanopy average -29.0+/-1.7 per thousand, -30.4+/-0.9 per thousand, and -34.0+/-1.5 per thousand, respectively. The delta(13)C of forest mammals show these differences, with the subcanopy browsers (okapi, dwarf antelope) having delta(13)C values for tooth enamel much more negative than subcanopy frugivores who derive their food from the canopy top, and from folivores and omnivores living in gap or clearing areas. Nitrogen isotopes in plants from this ecosystem have an average delta(15)N value of 5.4+/-1.8 per thousand and do not show significant differences at the 95% confidence interval between plants from the canopy top, from gaps in the canopy, and from the subcanopy. The delta(18)O(SMOW) values of surface waters in the study area are between -2.0 and -2.7. The delta(18)O(PDB) for tooth enamel ranged from -3 to +7 per thousand.

  13. The potential for application of ink stable isotope analysis in questioned document examination.

    PubMed

    Chesson, Lesley A; Tipple, Brett J; Barnette, Janet E; Cerling, Thure E; Ehleringer, James R

    2015-01-01

    We investigated a novel application of stable isotope abundance analysis of nitrogen (15N), carbon (13C), hydrogen (2H), and oxygen (18O) to characterize pen ink. We focused on both ballpoint and gel pen inks. We found that the isotope ratios of ink from pens purchased together in a package were similar and within-package stable isotope ratio variability was not significantly larger than the variability of isotope reference materials used during analysis. In contrast, the isotope ratios of ink from pens of the same brand purchased in three states of the continental USA were significantly different from each other and there was isotope ratio variation among pens of the same brand but different, unknown production periods. The stable isotope ratios of inked paper were statistically distinguishable using measured δ15N values. Paper inked with different gel pens was statistically distinguishable using measured δ2H values. The capacity of stable isotope ratios to differentiate among ballpoint inks as well as gel inks shows that stable isotope analysis may be a useful and quantifiable investigative technique for questioned document examination, although current sample size requirements limit its utility. Application of the technique in casework will require the development of micro-scale sampling and analysis methods.

  14. The potential for application of ink stable isotope analysis in questioned document examination.

    PubMed

    Chesson, Lesley A; Tipple, Brett J; Barnette, Janet E; Cerling, Thure E; Ehleringer, James R

    2015-01-01

    We investigated a novel application of stable isotope abundance analysis of nitrogen (15N), carbon (13C), hydrogen (2H), and oxygen (18O) to characterize pen ink. We focused on both ballpoint and gel pen inks. We found that the isotope ratios of ink from pens purchased together in a package were similar and within-package stable isotope ratio variability was not significantly larger than the variability of isotope reference materials used during analysis. In contrast, the isotope ratios of ink from pens of the same brand purchased in three states of the continental USA were significantly different from each other and there was isotope ratio variation among pens of the same brand but different, unknown production periods. The stable isotope ratios of inked paper were statistically distinguishable using measured δ15N values. Paper inked with different gel pens was statistically distinguishable using measured δ2H values. The capacity of stable isotope ratios to differentiate among ballpoint inks as well as gel inks shows that stable isotope analysis may be a useful and quantifiable investigative technique for questioned document examination, although current sample size requirements limit its utility. Application of the technique in casework will require the development of micro-scale sampling and analysis methods. PMID:25577004

  15. Stable isotopes in Lithuanian bioarcheological material

    NASA Astrophysics Data System (ADS)

    Skipityte, Raminta; Jankauskas, Rimantas; Remeikis, Vidmantas

    2015-04-01

    Investigation of bioarcheological material of ancient human populations allows us to understand the subsistence behavior associated with various adaptations to the environment. Feeding habits are essential to the survival and growth of ancient populations. Stable isotope analysis is accepted tool in paleodiet (Schutkowski et al, 1999) and paleoenvironmental (Zernitskaya et al, 2014) studies. However, stable isotopes can be useful not only in investigating human feeding habits but also in describing social and cultural structure of the past populations (Le Huray and Schutkowski, 2005). Only few stable isotope investigations have been performed before in Lithuanian region suggesting a quite uniform diet between males and females and protein intake from freshwater fish and animal protein. Previously, stable isotope analysis has only been used to study a Stone Age population however, more recently studies have been conducted on Iron Age and Late medieval samples (Jacobs et al, 2009). Anyway, there was a need for more precise examination. Stable isotope analysis were performed on human bone collagen and apatite samples in this study. Data represented various ages (from 5-7th cent. to 18th cent.). Stable carbon and nitrogen isotope analysis on medieval populations indicated that individuals in studied sites in Lithuania were almost exclusively consuming C3 plants, C3 fed terrestrial animals, and some freshwater resources. Current investigation demonstrated social differences between elites and country people and is promising in paleodietary and daily life reconstruction. Acknowledgement I thank prof. dr. G. Grupe, Director of the Anthropological and Palaeoanatomical State Collection in Munich for providing the opportunity to work in her laboratory. The part of this work was funded by DAAD. Antanaitis-Jacobs, Indre, et al. "Diet in early Lithuanian prehistory and the new stable isotope evidence." Archaeologia Baltica 12 (2009): 12-30. Le Huray, Jonathan D., and Holger

  16. Stable isotopes in river waters in the Tajik Pamirs: regional and temporal characteristics.

    PubMed

    Meier, Christiane; Knoche, Malte; Merz, Ralf; Weise, Stephan M

    2013-01-01

    The Gunt River catchment in the Central Pamirs is a representative of the headwater catchments of the Aral Sea Basin. It covers 14,000 km(2), spanning altitudes between 2000 and 6700 m a.s.l. In a monitoring network, water samples were taken at 30 sampling points every month and analysed for the stable water isotopes ((18)O and (2)H). Our first results show δ(2)H values in the range from-131.2 to-94.9 ‰ and δ(18)O values from-18.0 to-14.0 ‰. The stable isotope patterns in the catchment seem to follow a systematic way, dominated by an altitude effect with a mean Δ δ(2)H=-3.6 ‰/100 m. The observed seasonal variations can be explained by geographical aspects such as the influence of different wind systems as well as melting processes. PMID:24313375

  17. Quasiclassical trajectory studies of 18O(3P) + NO2 isotope exchange and reaction to O2 + NO on D0 and D1 potentials

    NASA Astrophysics Data System (ADS)

    Fu, Bina; Zhang, Dong H.; Bowman, Joel M.

    2013-07-01

    We report quasiclassical trajectory calculations for the bimolecular reaction 18O(3P) + NO2 on the recent potential energy surfaces of the ground (D0) and first excited (D1) states of NO3 [B. Fu, J. M. Bowman, H. Xiao, S. Maeda, and K. Morokuma, J. Chem. Theory. Comput. 9, 893 (2013)], 10.1021/ct3009792. The branching ratio of isotope exchange versus O2 + NO formation, as well as the product angular distributions and energy and rovibrational state distributions are presented. The calculations are done at the collision energy of relevance to recent crossed beam experiments [K. A. Mar, A. L. Van Wyngarden, C.-W. Liang, Y. T. Lee, J. J. Lin, and K. A. Boering, J. Chem. Phys. 137, 044302 (2012)], 10.1063/1.4736567. Very good agreement is achieved between the current calculations and these experiments for the branching ratio and final translational energy and angular distributions of isotope exchange products 16O(3P) + NO2 and O2 + NO formation products. The reactant 18O atom results in 18O16O but not N18O for the O2 + NO formation product channel, consistent with the experiment. In addition, the detailed vibrational and rotational state information of diatomic molecules calculated currently for the 34O2 + NO formation channel on D0 and D1 states are in qualitative agreement with the previous experimental and theoretical results of the photodissociation of NO3 and are consistent with older thermal bimolecular kinetics measurements.

  18. A stable isotope study of water movements with typical vegetation cover in the North China Plain

    NASA Astrophysics Data System (ADS)

    Ma, Bin; Liang, Xing; Liu, Shaohua; Jin, Menggui; Li, Jing

    2015-04-01

    The stable isotope 2H and 18O are often used as natural tracers in subsurface water pathways in semi-arid areas. The stable isotopic compositions in precipitation, soil water and groundwater were observed to assess the temporal variations in soil water flow at three sites covered by grass (Carex humili and Carex lanceolata) (site A), poplar (Ponulus hopeiensis) (site B) and winter wheat (Triticum asetivum) and summer maize (Zea mays) (site C) in the shallow groundwater area in the North China Plain (NCP) from April 2012 to October 2013. Precipitation isotopes resulted in a meteoric water line of δ2H =7.6δ18O -3.7 and showed a typical seasonal variation for δ2H (-98.9 to -13.3) and δ18O (-12.0 to -1.7). The seasonality in the shallow groundwater was further subdued due to the evaporation and mixing and diffusional exchange with stored water held in the soil pores within the unsaturated zone. Shallow groundwater was mainly recharged by precipitation in the rainy season. Soil water isotope profiles were sampled at depths of 10 cm down to 150 cm every 10 cm for the three sites. The vertical profiles of soil water δ18O showed large variations in the superficial 10 cm layer under the precipitation input and evapotranspiration effects. The soil water δ18O decreased and soil moisture increased with depth ( 70 cm) due to continuously evapotranspiration for the three sites though that at site B showed more positive δ18O values and smaller soil moisture than those at site A and C. The signal of individual rainstorm event in the summer with low δ18O values could be traced down to a depth of 40 cm that mixed with antecedent mobile soil water and to 120 cm due to a fast and direct preferential infiltration of the input rainwater that bypassed the upper soil layer at sites B and C. Keywords: stable isotopes; soil water pathways; groundwater recharge; North China Plain

  19. Stable isotope and elemental analysis in ants.

    PubMed

    Smith, Chris R; Tillberg, Chadwick V

    2009-07-01

    Over the past 20 yr, the use of stable isotopes to infer feeding ecology and the examination of how energetic and elemental exchanges are affected by and affect life (ecological stoichiometry) have gained momentum. The ecological diversity of ants makes them interesting models to explore dietary ecology and their role in food webs. Moreover, their ecological dominance in most habitats facilitates sampling. The protocol described here will produce samples adequate for submission to most labs that specialize in high-throughput analysis of stable isotopes; one should check with any particular lab for specific submission instructions. Note, however, that this protocol is designed specifically for the quantification of the natural abundance of stable isotopes; it does not cover the preparation of trace samples. PMID:20147207

  20. Oxygen isotope ratios (18O/16O) of hemicellulose-derived sugar biomarkers in plants, soils and sediments as paleoclimate proxy I: Insight from a climate chamber experiment

    NASA Astrophysics Data System (ADS)

    Zech, Michael; Mayr, Christoph; Tuthorn, Mario; Leiber-Sauheitl, Katharina; Glaser, Bruno

    2014-02-01

    The oxygen isotopic composition of cellulose is a valuable proxy in paleoclimate research. However, its application to sedimentary archives is challenging due to extraction and purification of cellulose. Here we present compound-specific δ18O results of hemicellulose-derived sugar biomarkers determined using gas chromatography-pyrolysis-isotope ratio mass spectrometry, which is a method that overcomes the above-mentioned analytical challenges. The biomarkers were extracted from stem material of different plants (Eucalyptus globulus, Vicia faba and Brassica oleracea) grown in climate chamber experiments under different climatic conditions. The δ18O values of arabinose and xylose range from 31.4‰ to 45.9‰ and from 28.7‰ to 40.8‰, respectively, and correlate highly significantly with each other (R = 0.91, p < 0.001). Furthermore, δ18Ohemicellulose (mean of arabinose and xylose) correlate highly significantly with δ18Oleaf water (R = 0.66, p < 0.001) and significantly with modeled δ18Ocellulose (R = 0.42, p < 0.038), as well as with relative air humidity (R = -0.79, p < 0.001) and temperature (R = -0.66, p < 0.001). These findings confirm that the hemicellulose-derived sugar biomarkers, like cellulose, reflect the oxygen isotopic composition of plant source water altered by climatically controlled evapotranspirative 18O enrichment of leaf water. While relative air humidity controls most rigorously the evapotranspirative 18O enrichment, the direct temperature effect is less important. However, temperature can indirectly exert influence via plant physiological reactions, namely by influencing the transpiration rate which affects δ18Oleaf water due to the Péclet effect. In a companion paper (Tuthorn et al., this issue) we demonstrate the applicability of the hemicellulose-derived sugar biomarker δ18O method to soils and provide evidence from a climate transect study confirming that relative air humidity exerts the dominant control on evapotranspirative 18O

  1. Oxygen isotope effects of enzyme-catalyzed organophosphorus hydrolysis reactions: implications for interpretation of dissolved PO4 δ18O values in natural waters

    NASA Astrophysics Data System (ADS)

    Liang, Y.; Blake, R. E.

    2002-12-01

    The geochemical cycling of P in Earth surface environments is controlled largely by biota. It has been recently demonstrated that intracellular cycling of P in microbial cultures and biological turnover of P in natural waters leads to temperature-dependent O isotope equilibrium between dissolved inorganic PO4 (Pi) and ambient water, and that the δ18O of Pi can be a useful tracer of biological reactions and P cycling in aquatic systems/sediments. Oxygen isotope exchange between Pi and water during biological turnover of P is catalyzed by enzymes at low-temperature. Phosphoenzymes play a crucial role in the intracellular functions of all living organisms and also have important extracellular functions in aquatic ecosystems such as regeneration of Pi from organophosphorus compounds (e.g., phosphoesters). Laboratory experiments indicate that extracellular enzyme reactions may result in incomplete Pi turnover and non-equilibrium Pi-water O isotope exchange. Determination of the O isotope effects of phosphoenzyme-catalyzed reactions is fundamental to the understanding of mechanisms of PO4-water O isotope exchange, pathways of biogeochemical P cycling, and interpretation of PO4 δ18O values from natural systems. Here we report on the O isotope fractionation between enzymatically-released Pi and water, in cell-free abiotic systems. Alkaline phosphatase (Apase) is a non-specific phosphohydrolase commonly found in fresh and marine coastal waters that catalyzes the hydrolysis of Pi from phosphomonoesters. We examined the O isotope effects of Apase derived from both microbial and eukaryotic sources and acting on different phosphomonoester substrates (e.g., α-D-Glucose 1-Phosphate, β-Glycerophosphate, AMP) in 18O-labeled waters. Oxygen isotope ratios of Pi released by Apase indicate that only 1 of the 4 O atoms in PO4 is incorporated from water with little or no apparent O isotopic fractionation at the site of incorporation. This observation is consistent with

  2. Experimental assessment of environmental influences on the stable isotopic composition of Daphnia pulicaria and their ephippia

    NASA Astrophysics Data System (ADS)

    Schilder, J.; Tellenbach, C.; Möst, M.; Spaak, P.; van Hardenbroek, M.; Wooller, M. J.; Heiri, O.

    2015-02-01

    The stable isotopic composition of fossil resting eggs (ephippia) of Daphnia spp. is being used to reconstruct past environmental conditions in lake ecosystems. However, the underlying assumption that the stable isotopic composition of the ephippia reflects the stable isotopic composition of the parent Daphnia, of their diet and of the environmental water have yet to be confirmed in a controlled experimental setting. We performed experiments with Daphnia pulicaria cultures, which included a control treatment conducted at 12 °C in filtered lake water and with a diet of fresh algae, and three treatments in which we manipulated the stable carbon isotopic composition (δ13C value) of the algae, stable oxygen isotopic composition (δ18O value) of the water, and the water temperature, respectively. The stable nitrogen isotopic composition (δ15N value) of the algae was similar for all treatments. At 12 °C, differences in algal δ13C values and in δ18O values of water are reflected in those of Daphnia. The differences between ephippia and Daphnia stable isotope ratios were similar in the different treatments (δ13C: + 0.2 ± 0.4‰ (SD); δ15N: -1.6 ± 0.4‰; δ18O: -0.9 ± 0.4‰) indicating that changes in dietary δ13C and δ18O values of water are passed on to these fossilizing structures. A higher water temperature (20 °C) resulted in lower δ13C values in Daphnia and ephippia than in the other treatments with the same food source and in a minor change in the difference between δ13C values of ephippia and Daphnia (to -1.3 ± 0.3‰). This may have been due to microbial processes or increased algal respiration rates in the experimental containers, which may not affect Daphnia in natural environments. There was no significant difference in the offset between δ18O and δ15N values of ephippia and Daphnia between the 12 °C and 20 °C treatments, but the δ18O values of Daphnia and ephippia were on average 1.2‰ lower at 20 °C compared with 12 °C. We conclude

  3. The Stable Isotopic Composition of Atmospheric CO2

    NASA Astrophysics Data System (ADS)

    Yakir, D.

    2003-12-01

    When a bean leaf was sealed in a closed chamber under a lamp (Rooney, 1988), in two hours the atmospheric CO2 in the microcosm reached an isotopic steady state with a 13C abundance astonishingly similar to the global mean value of atmospheric CO2 at that time (-7.5‰ in the δ13C notation introduced below). Almost concurrently, another research group sealed a suspension of asparagus cells in a different type of microcosm in which within about two hours the atmospheric O2 reached an isotopic steady state with 18O enrichment relative to water in the microcosm that was, too, remarkably similar to the global-scale offset between atmospheric O2 and mean ocean water (21‰ versus 23.5‰ in the δ18O notation introduced below; Guy et al., 1987). These classic experiments capture some of the foundations underlying the isotopic composition of atmospheric CO2 and O2. First, in both cases the biological system rapidly imposed a unique isotopic value on the microcosms' atmosphere via their massive photosynthetic and respiratory exchange of CO2 and O2. Second, in both cases the biological system acted on materials with isotopic signals previously formed by the global carbon and hydrological cycles. That is, the bean leaf introduced its previously formed organic matter (the source of the CO2 respired into microcosm's atmosphere), and the asparagus cells were introduced complete with local tap water (from which photosynthesis released molecular oxygen). Therefore, while the isotopic composition of the biological system used was slave to long-term processes, intense metabolic processes centered on few specific enzymes (Yakir, 2002) dictated the short-term atmospheric composition.In a similar vein, on geological timescales of millions of years, the atmosphere and its isotopic composition are integral parts of essentially a single dynamic ocean-atmosphere-biosphere system. This dynamic system exchanges material, such as carbon and oxygen, with the sediments and the lithosphere via

  4. 15N2 formation and fast oxygen isotope exchange during pulsed 15N18O exposure of MnOx/CeO2

    SciTech Connect

    Kwak, Ja Hun; Szanyi, Janos

    2014-12-23

    Pulsing 15N18O onto an annealed 1% Mn16Ox/Ce16O2 catalyst resulted in very fast oxygen isotope exchange and 15N2 formation at 295 K. In the 1st 15N18O pulse, due to the presence of large number of surface oxygen defects, extensive 15N218O and 15N2 formations were observed. In subsequent pulses oxygen isotope exchange dominated as a result of highly labile oxygen in the oxide. We gratefully acknowledge the US Department of Energy (DOE), Office of Energy Efficiency and Renewable Energy/Vehicle Technologies Program for the support of this work. The research described in this paper was performed at the Environmental Molecular Sciences Laboratory (EMSL), a national scientific user facility sponsored by the DOE’s Office of Biological and Environmental Research and located at Pacific Northwest National Laboratory (PNNL). PNNL is operated for the US DOE by Battelle.

  5. Impact of Tibetan Plateau uplift on Asian climate and stable oxygen isotopes in precipitation

    NASA Astrophysics Data System (ADS)

    Botsyun, Svetlana; Sepulchre, Pierre; Risi, Camille; Donnadieu, Yannick

    2016-04-01

    Surface elevation provides crucial information for understanding both geodynamic mechanisms of Earth's interior and influence of mountains growth on climate. Stable oxygen isotopes paleoaltimetry is considered to be a very efficient technic for reconstruction of the elevation history of mountains belts, including Tibetan Plateau and the Himalayas. This method relies on the difference between δ18O of paleo-precipitation reconstructed using the natural archives, and modern measured values for the point of interest. However, stable-isotope paleoaltimetry is potentially hampered by the fact that the presumed constancy of altitude-δ18O relationships through time might not be valid and climate changes affects δ18O in precipitation. We use the isotope-equipped atmospheric general circulation model LMDZ-iso for modeling Asia climate variations and associated δ18O in precipitation linked with Himalayas and Tibetan Plateau uplift. Experiments with reduced height over the Tibetan Plateau and the Himalayas have been designed. For the purpose of understanding where and how simulated complex climatic changes linked with the growth of mountains affect δ18O in precipitation we develop a theoretical expression for the precipitation composition. Our results show that modifying Tibetan Plateau height alters large-scale atmospheric dynamics including monsoon circulation and subsidence and associated climate variables, namely temperature, precipitation, relative humidity and cloud cover. In turn, δ18O signal decomposition results show that the isotopic signature of rainfall is very sensitive to climate changes related with the growth of the Himalayas and Tibetan Plateau, notably changes in relative humidity and precipitation amount. Topography appears to be the main controlling factor for only 40{%} of the sites where previous paleoelevation studies have been performed. Change of moisture sources linked with Asian topography uplift is shown to be not sufficient to yield a strong

  6. A stable isotope approach to assessing water loss in fruits and vegetables during storage.

    PubMed

    Greule, Markus; Rossmann, Andreas; Schmidt, Hanns-Ludwig; Mosandl, Armin; Keppler, Frank

    2015-02-25

    Plant tissue water is the source of oxygen and hydrogen in organic biomatter. Recently, we demonstrated that the stable hydrogen isotope value (δ(2)H) of plant methoxyl groups is a very reliable and easily available archive for the δ(2)H value of this tissue water. Here we show in a model experiment that the δ(2)H values of methoxyl groups remain unchanged after water loss during storage of fruits and vegetables under controlled conditions, while δ(2)H and δ(18)O values of tissue water increase. This enhancement is plant-dependent, and the correlation differs from the meteoric water line. The δ(18)O value is better correlated to the weight decrease of the samples. Therefore, we postulate that the δ(2)H value of methoxyl groups and the δ(18)O value of tissue water are suitable parameters for checking postharvest alterations of tissue water, either addition or loss.

  7. Stable isotopes provide insight into population structure and segregation in eastern North Atlantic sperm whales.

    PubMed

    Borrell, Asunción; Velásquez Vacca, Adriana; Pinela, Ana M; Kinze, Carl; Lockyer, Christina H; Vighi, Morgana; Aguilar, Alex

    2013-01-01

    In pelagic species inhabiting large oceans, genetic differentiation tends to be mild and populations devoid of structure. However, large cetaceans have provided many examples of structuring. Here we investigate whether the sperm whale, a pelagic species with large population sizes and reputedly highly mobile, shows indication of structuring in the eastern North Atlantic, an ocean basin in which a single population is believed to occur. To do so, we examined stable isotope values in sequential growth layer groups of teeth from individuals sampled in Denmark and NW Spain. In each layer we measured oxygen- isotope ratios (δ(18)O) in the inorganic component (hydroxyapatite), and nitrogen and carbon isotope ratios (δ(15)N: δ(13)C) in the organic component (primarily collagenous). We found significant differences between Denmark and NW Spain in δ(15)N and δ(18)O values in the layer deposited at age 3, considered to be the one best representing the baseline of the breeding ground, in δ(15)N, δ(13)C and δ(18)O values in the period up to age 20, and in the ontogenetic variation of δ(15)N and δ(18)O values. These differences evidence that diet composition, use of habitat and/or migratory destinations are dissimilar between whales from the two regions and suggest that the North Atlantic population of sperm whales is more structured than traditionally accepted.

  8. Stable Isotopes Provide Insight into Population Structure and Segregation in Eastern North Atlantic Sperm Whales

    PubMed Central

    Borrell, Asunción; Velásquez Vacca, Adriana; Pinela, Ana M.; Kinze, Carl; Lockyer, Christina H.; Vighi, Morgana; Aguilar, Alex

    2013-01-01

    In pelagic species inhabiting large oceans, genetic differentiation tends to be mild and populations devoid of structure. However, large cetaceans have provided many examples of structuring. Here we investigate whether the sperm whale, a pelagic species with large population sizes and reputedly highly mobile, shows indication of structuring in the eastern North Atlantic, an ocean basin in which a single population is believed to occur. To do so, we examined stable isotope values in sequential growth layer groups of teeth from individuals sampled in Denmark and NW Spain. In each layer we measured oxygen- isotope ratios (δ18O) in the inorganic component (hydroxyapatite), and nitrogen and carbon isotope ratios (δ15N: δ13C) in the organic component (primarily collagenous). We found significant differences between Denmark and NW Spain in δ15N and δ18O values in the layer deposited at age 3, considered to be the one best representing the baseline of the breeding ground, in δ15N, δ13C and δ18O values in the period up to age 20, and in the ontogenetic variation of δ15N and δ18O values. These differences evidence that diet composition, use of habitat and/or migratory destinations are dissimilar between whales from the two regions and suggest that the North Atlantic population of sperm whales is more structured than traditionally accepted. PMID:24324782

  9. Determination of delta2H and delta18O in saline oil-associated waters: the question of simple vacuum distillation of water samples prior to isotopic analyses.

    PubMed

    Porowski, Adam; Kowski, Peter

    2008-06-01

    The paper deals with analytical and procedural aspects of delta18O and delta2H determination in saline oil-associated waters. The main objective of the study was to show experimentally the qualitative and quantitative applicability of the simple vacuum distillation of saline oil-associated waters while routine procedures of water isotopic analyses are applied. Additionally, two standard off-line techniques of delta2H determination in water - the zinc and the chromium method - have been compared. Each time a typical isotope salt effect has been tracked on the Dead Sea water. The results clearly show that application of the simple vacuum distillation improve the accuracy and reproducibility of delta2H determinations, especially in chromium off-line technique which appeared to be more sensitive to water salinity. The simple vacuum distillation does not improve the quality of delta18O determinations in the range of water salinities studied. Its application to high concentrated brines (for example, Dead Sea water) decreases the time of equilibration but still propagate the isotopic error connected with low water activity (in the case of 18O/16O ratio) and the incomplete water extraction from the remaining salts (in the case of 2H/1H ratio); in consequence, its time-consuming application seems to be baseless.

  10. Stable isotope distribution in precipitation in Romania and its relevance for palaeoclimatic studies

    NASA Astrophysics Data System (ADS)

    Perşoiu, Aurel; Nagavciuc, Viorica; Bădăluţă, Carmen

    2014-05-01

    A surge of recent studies in Romania have targeted various aspects of palaeoclimate (based on stable isotopes in ice, speleothems, tree rings), mineral water origin, wine and other juices provenance. However, while much needed, these studies lack a stable isotope in precipitation background, with only two LMWL's being published so far. In this paper we discuss the links between the stable isotopic composition of precipitation (δ18O and δ2H), climate (air temperature, precipitation amount and large scale circulation) and their relevance for the palaeocllimatic interpretation of stable isotope values in cave ice, cryogenic calcite and tree rings from different sites in Romania. Most of the precipitation in Romania is delivered by the Westerlies, bringing moisture from the North Atlantic; however, their influence is greatly reduced in the eastern half of the country where local evaporative sources play an important role in the precipitation balance. The SW is dominated by water masses from the Mediterranean Sea, while the SE corner clearly draws most of the moisture from the Black Sea and strongly depleted North Atlantic vapor masses. In 2012, Romania experienced the worst draught in 60 years, possibly due to a northward shift of the jest stream associated to blocking conditions in summer, which led to a more northern penetration of the Mediterranean-derived air masses, as well increased precipitation of re-evaporated waters. We have further analyzed cave drip water (δ18O and δ2H), cryogenic cave calcite (δ18O and δ13C) and tree rings (δ18O and δ13C) from selected sites across NW Romania, where the water isotopes in precipitation showed the best (and easiest to understand, given the climatic conditions in 2012) correlation with climatic parameters. Our results that 1) δ18O and δ2H in cave ice are a good proxy for late summer through early winter air temperature; 2) δ13C in cryogenic cave calcite are possible indicators of soil humidity and 3) δ18O in pine

  11. The stable isotope amount effect: New insights from NEXRAD echo tops, Luquillo Mountains, Puerto Rico

    USGS Publications Warehouse

    Schol, M.A.; Shanley, J.B.; Zegarra, J.P.; Coplen, T.B.

    2009-01-01

    The stable isotope amount effect has often been invoked to explain patterns of isotopic composition of rainfall in the tropics. This paper describes a new approach, correlating the isotopic composition of precipitation with cloud height and atmospheric temperature using NEXRAD radar echo tops, which are a measure of the maximum altitude of rainfall within the clouds. The seasonal differences in echo top altitudes and their corresponding temperatures are correlated with the isotopic composition of rainfall. These results offer another factor to consider in interpretation of the seasonal variation in isotopic composition of tropical rainfall, which has previously been linked to amount or rainout effects and not to temperature effects. Rain and cloud water isotope collectors in the Luquillo Mountains in northeastern Puerto Rico were sampled monthly for three years and precipitation was analyzed for ??18O and ??2H. Precipitation enriched in , 18O and 2H occurred during the winter dry season (approximately December-May) and was associated with a weather pattern of trade wind showers and frontal systems. During the summer rainy season (approximately June-November), precipitation was depleted in 18O and 2H and originated in low pressure systems and convection associated with waves embedded in the prevailing easterly airflow. Rain substantially depleted in 18O and 2H compared to the aforementioned weather patterns occurred during large low pressure systems. Weather analysis showed that 29% of rain input to the Luquillo Mountains was trade wind orographic rainfall, and 30% of rainfall could be attributed to easterly waves and low pressure systems. Isotopic signatures associated with these major climate patterns can be used to determine their influence on streamflow and groundwater recharge and to monitor possible effects of climate change on regional water resources.

  12. Long-Term Precipitation Isotope Ratios (δ18O, δ2H, d-excess) in the Northeast US Reflect Atlantic Ocean Warming and Shifts in Moisture Sources

    NASA Astrophysics Data System (ADS)

    Puntsag, T.; Welker, J. M.; Mitchell, M. J.; Klein, E. S.; Campbell, J. L.; Likens, G.

    2014-12-01

    The global water cycle is exhibiting dramatic changes as global temperatures increase resulting in increases in: drought extremes, flooding, alterations in storm track patterns with protracted winter storms, and greater precipitation variability. The mechanisms driving these changes can be difficult to assess, but the spatial and temporal patterns of precipitation water isotopes18O, δ2H, d-excess) provide a means to help understand these water cycle changes. However, extended temporal records of isotope ratios in precipitation are infrequent, especially in the US. In our study we analyzed precipitation isotope ratio data from the Hubbard Brook Experimental Forest in New Hampshire that has the longest US precipitation isotope record, to determine: 1) the monthly composited averages and trends from 1967 to 2012 (45 years); ; 2) the relationships between abiotic properties such as local temperatures, precipitation type, storm tracks and isotope ratio changes; and 3) the influence of regional shifts in moisture sources and/or changes in N Atlantic Ocean water conditions on isotope values. The seasonal variability of Hubbard Brook precipitation isotope ratios is consistent with other studies, as average δ18O values are ~ -15‰ in January and ~ -5 ‰ in July. However, over the 45 year record there is a depletion trend in the δ 18O values (becoming isotopically lighter with a greater proportion of 16O), which coupled with less change in δ 2H leads to increases in d-excess values from ~ -10‰ around 1970 to greater than 10‰ in 2009. These changes occurred during a period of warming as opposed to cooling local temperatures indicating other processes besides temperature are controlling long-term water isotope traits in this region. We have evidence that these changes in precipitation isotope traits are controlled in large part by an increases in moisture being sourced from a warming N Atlantic Ocean that is providing evaporated, isotopically

  13. Stable Isotope Evidence for Planetary Differentiation

    NASA Astrophysics Data System (ADS)

    Shahar, A.; Mao, W. L.; Schauble, E. A.; Caracas, R.; Reagan, M. M.; Gleason, A. E.

    2015-12-01

    Planetary differentiation occurred at high temperature and varying oxygen fugacity, on bodies with varying compositions and internal pressures. The specific conditions at which bodies differentiated and the chemical fingerprints left by differentiation can be investigated by measuring stable isotope ratios in natural samples. Much can be learned by combining those data with experiments that systematically investigate the chemical and physical conditions within differentiating bodies. In this talk we focus on one variable in particular that has not been well defined with respect to stable isotope fractionation: pressure. We will present new iron isotope data on how pressure affects isotope fractionation factors for a number of iron compounds relative to silicate. The processes governing iron isotope fractionation in igneous rocks have been debated extensively over the past decade. Analyses of natural samples show that iron isotopes are fractionated at both the whole rock and mineral scales. This fractionation has been interpreted to be a result of several processes including a possible signature of high pressure core formation. We have collected new high pressure synchrotron nuclear resonant inelastic x-ray scattering data from Sector 16-ID-D at the Advanced Photon Source on 57Fe enriched Fe, FeO, FeHx and Fe3C. Our data show clear trends with pressure implying that not only does pressure have an effect on the iron isotope beta factors but also a fractionation amongst the alloys. This suggests that depending on the light element in the core, there will be a different resulting signature in the iron isotope record. We will discuss the likelihood of different light elements in the core based on these results, as well as the theoretical predictions for the same phases. Finally, we will present the fractionation expected between metal and silicate at high pressure and high temperature in order to determine if core formation would indeed leave an isotopic signature in

  14. Stable carbon and oxygen isotope fractionation processes during speleothem growth: systematic investigation in novel laboratory experiments

    NASA Astrophysics Data System (ADS)

    Scholz, D.; Hansen, M.; Dreybrodt, W.

    2012-04-01

    The most widely applied climate proxies in speleothems are stable carbon and oxygen isotopes (δ13C and δ18O). The interpretation of the stable isotope signals in terms of past temperature and/or precipitation variability is complex because both δ18O and δ13C depend on a complex interplay of various processes occurring in the atmosphere, the soil and karst above the cave and inside the cave. Quantitative reconstruction of climate parameters such as temperature and precipitation has, thus, remained impossible so far. Here we present several novel laboratory experiments aiming to understand the basic physical and chemical processes affecting the δ18O and δ13C signals during precipitation of calcium carbonate on the stalagmite surface. In particular, we aim to quantify the influence of kinetic isotope fractionation and verify recently published modelling studies (Dreybrodt, 2008; Scholz et al., 2009, Dreybrodt and Scholz, 2011). Several experiments are conducted: Degassing of CO2 from a thin film of water sparged with CO2 flowing down an inclined glass plate. pH and electric conductivity are systematically documented in order to monitor degassing of CO2. The results show that degassing of CO2 is fast, and the pCO2 of the solution is in equilibrium with the atmosphere after a short distance of flow. Carbon isotope exchange between atmospheric CO2 and dissolved bicarbonate. The results show that carbon isotope exchange may have a significant effect on the δ13C value of the dissolved bicarbonate and, thus, speleothem calcite, in particular for slow drip rates. Degassing of CO2 and calcite precipitation from a thin film of water supersaturated with respect to calcite flowing down an inclined calcium carbonate plate. Drip water is sampled after different lengths of flow path and, thus, different residence times on the plate, and pH, electrical conductivity and the stable isotope composition of the water are determined. Decreasing conductivity with increasing distance

  15. Variation in stable isotope ratios of monthly rainfall in the Douala and Yaounde cities, Cameroon: local meteoric lines and relationship to regional precipitation cycle

    NASA Astrophysics Data System (ADS)

    Wirmvem, Mengnjo Jude; Ohba, Takeshi; Kamtchueng, Brice Tchakam; Taylor, Eldred Tunde; Fantong, Wilson Yetoh; Ako, Ako Andrew

    2016-04-01

    Hydrogen (D) and oxygen (18O) stable isotopes in precipitation are useful tools in groundwater recharge and climatological investigations. This study investigated the isotopes in rainfall during the 2013 and 2014 hydrological years in the Douala and Yaounde urban cities. The objectives were to generate local meteoric water lines (LMWLs), define the spatial-temporal variations of the isotopes in rainwater and their relationship to the regional precipitation cycle, and determine the factors controlling the isotopic variation. The LWMLs in Douala and Yaounde were δD = 7.92δ18O + 12.99 and δD = 8.35δ18O + 15.29, respectively. The slopes indicate isotopic equilibrium conditions during rain formation and negligible evaporation effect during rainfall. Precipitation showed similar wide ranges in δ18O values from -5.26 to -0.75 ‰ in Douala and -5.8 to +1.81 ‰ in Yaounde suggesting a common moisture source from the Atlantic Ocean. Enriched weighted mean δ18O (wδ18O) values during the low pre- and post-monsoon showers coincided with low convective activity across the entire region. Enriched isotopic signatures also marked the West African monsoon transition phase during each hydrological year. Abrupt wδ18O depletion after the transition coincided with the monsoon onset in the region. Peak periods of monsoonal rainfall, associated with high convective activities, were characterised by the most depleted wδ18O values. Controls on isotopic variations are the amount effect and moisture recycling. The stable isotope data provide a tool for groundwater recharge studies while the isotopic correlation with regional rainfall cycle demonstrate their use as markers of moisture circulation and detecting climatic changes in precipitation.

  16. Hydrochemical and isotopic (2H, 18O and 37Cl) constraints on evolution of geothermal water in coastal plain of Southwestern Guangdong Province, China

    NASA Astrophysics Data System (ADS)

    Chen, Liuzhu; Ma, Teng; Du, Yao; Xiao, Cong; Chen, Xinming; Liu, Cunfu; Wang, Yanxin

    2016-05-01

    Geothermal energy is abundant in Guangdong Province of China, however, majority of it is still unexploited. To take full advantage of this energy, it is essential to know the information of geothermal system. Here, physical parameters such as pH and temperature, major ion (Na+, Ca2 +, Mg2 +, Cl-, SO42 - and HCO3-), trace elements (Br-, Sr2 +, Li+ and B3 +) and stable isotopes (2H, 18O and 37Cl) in geothermal water, non-geothermal water (river water, cold groundwater) and seawater were used to identify the origin and evolution of geothermal water in coastal plain of Southwest of Guangdong. Two separate groups of geothermal water have been identified in study area. Group A, located in inland of study area, is characterized by Na+ and HCO3-. Group B, located in coastal area, is characterized by Na+ and Cl-. The relationships of components vs. Cl for different water samples clearly suggest the hydrochemical differences caused by mixing with seawater and water-rock interactions. It's evident that water-rock interactions under high temperature make a significant contribution to hydrochemistry of geothermal water for both Group A and Group B. Besides, seawater also plays an important role during geothermal water evolution for Group B. Mixing ratios of seawater with geothermal water for Group B are calculated by Cl and Br binary diagram, the estimated results show that about < 1% to < 35% of seawater has mixed into geothermal water, and seawater might get into the geothermal system by deep faults. Molar Na/Cl ratios also support these two processes. Geothermal and non-geothermal water samples plot around GMWL in the δ2H vs. δ18O diagram, indicating that these samples have a predominant origin from meteoric water. Most of geothermal water samples display δ37Cl values between those of the non-geothermal water and seawater samples, further reveals three sources of elements supply for geothermal water, including atmospheric deposition, bedrocks and seawater, which show a

  17. Interpreting δD and δ18O isotopic signals of ambient water vapor in PNW coniferous forest using a high frequency CRDS analyzer

    NASA Astrophysics Data System (ADS)

    Allen, S. T.; Bond, B. J.; McDonnell, J. J.; Brooks, J. R.; Thomas, C. K.

    2010-12-01

    Wavelength-Scanned Cavity Ring-Down Spectroscopy provides real-time simultaneous measurement of stable isotopologues of water vapor in natural environments. Continuous, high-frequency sampling provides a new and exciting look at water cycle processes and creates many new possibilities for studying the vapor phase of the hydrologic cycle. However, as with any new tool, the first challenge is to understand the sources of variability in the signal. This includes disentangling potential instrument variability from environmental variability as well as the identification and quantification of environmental end members. We deployed a Picarro L-1102 Liquid / Vapor analyzer at the mouth of a small watershed in the H.J. Andrews Experimental Forest located in the West-Central Oregon Cascades range in November, 2009. The steeply-sloped watershed is covered by a closed-canopied, young-mature Douglas fir forest; it has been used for many previous ecological, hydrological, and meteorological studies. The data reveal very high diel variability in δD in and δ18O as well as δD to δ18O ratios and a strong deviation from the global meteoric water line. A hysteresis effect differs dramatically from one day to the next and confounds apparent trends. To interpret these results, we are conducting controlled tests of instrument performance and we propose a plan to partition individual vapor source contributions. Application of this vapor signature to ecological or hydrological studies requires knowledge of individual end-member contributions to the isotope measurements. We hypothesize that by determining end-member fluxes and in-situ fractionation factors paired with micrometeorological data, we can better understand processes driving these patterns. Combined with meteorological tower data, high frequency data allows the possibility of scaling up from continuous point measurements to ecosystem-scale processes. Previous studies in this watershed have demonstrated the ability to estimate

  18. UNCERTAINTY IN SOURCE PARTITIONING USING STABLE ISOTOPES

    EPA Science Inventory

    Stable isotope analyses are often used to quantify the contribution of multiple sources to a mixture, such as proportions of food sources in an animal's diet, C3 vs. C4 plant inputs to soil organic carbon, etc. Linear mixing models can be used to partition two sources with a sin...

  19. Nitrate stable isotopes: Tools for determining nitrate sources among different land uses in the Mississippi River Basin

    USGS Publications Warehouse

    Chang, Cecily C.Y.; Kendall, C.; Silva, S.R.; Battaglin, W.A.; Campbell, D.H.

    2002-01-01

    A study was conducted to determine whether NO3- stable isotopes (??15N and ??18O), at natural abundance levels, could discriminate among NO3- sources from sites with different land uses at the basin scale. Water samples were collected from 24 sites in the Mississippi River Basin from five land-use categories: (1) large river basins (>34 590 km2) draining multiple land uses and smaller basins in which the predominant land use was (2) urban (3) undeveloped, (4) crops, or (5) crops and livestock. Our data suggest that riverine nitrates from different land uses have overlapping but moderately distinct isotopic signatures. ??18O data were critical in showing abrupt changes in NO3- source with discharge. The isotopic values of large rivers resembled crop sites, sites with livestock tended to have ??15N values characteristic of manure, and urban sites tended to have high ??18O values characteristic of atmospheric nitrate.

  20. Stable isotope investigations of chlorinated aliphatic hydrocarbons.

    SciTech Connect

    Abrajano, T.; Heraty, L. J.; Holt, B. D.; Huang, L.; Sturchio, N. C.

    1999-06-01

    Stable isotope ratio measurements for carbon (C) and chlorine (Cl) can be used to elucidate the processes affecting transformation and transportation of chlorinated aliphatic hydrocarbons (CAHs) in the environment. Methods recently developed in our laboratory for isotopic analysis of CAHs have been applied to laboratory measurements of the kinetic isotope effects associated with aerobic degradation of dichloromethane (DCM) and with both anaerobic and aerobic cometabolic degradation of trichlomethene (TCE) in batch and column microbial cultures. These experimental determinations of fractionation factors are crucial for understanding the behavior of CAHs in complex natural systems, where the extent of biotransformation can be masked by dispersion and volatilization. We have also performed laboratory investigations of kinetic isotope effects accompanying evaporation of CAHs, as well as field investigations of natural attenuation and in situ remediation of CAHs in a number of contaminated shallow aquifers at sites operated by the federal government and the private sector.

  1. sup 18 O/ sup 16 O and sup 13 C/ sup 12 C in lower Paleozoic articulate brachiopods: Implications for the isotopic composition of seawater

    SciTech Connect

    Wadleigh, M.A. ); Veizer, J. Ruhr Univ., Bochum )

    1992-01-01

    Three hundred and eleven articulate brachiopods, with extensive geographic coverage, spanning the Cambrian to Silurian stratigraphic interval, were analyzed for oxygen and carbon isotopic composition. Cambrian samples have {delta}{sup 18}O {le} {minus}7{per thousand}, Ordovician samples {le} {minus}2.4{per thousand}, and Silurian samples {le} {minus}1.9{per thousand}, confirming the previously established trend towards lighter isotopic compositions with increasing age throughout the Lower Paleozoic. Forty-nine best preserved' Ordovician and Silurian samples were identified based on scanning electron microscopy and trace element analysis. They were found to bracket the isotopic compositions of over 85% of specimens from these stratigraphic intervals supporting widespread preservation of the isotopic signal. Some latest Ordovician and Lower Ludlovian samples associated with shale sequences are apparently enriched' in {sup 18}O. These are interpreted as an environmental phenomenon, perhaps related to water temperature and glaciation. A number of Silurian samples of varying genera and stratigraphic levels are highly enriched in {sup 13}C, up to +6{per thousand}. Some are shale related, but some are associated with carbonate-bearing basins. These are also thought to represent near-original' compositions, but a single environmental cause is unknown. The present data show that luminescence is not a decisive criterion for evaluating the degree of brachiopod preservation. Whole-shell values were isotopically similar to their nonluminescent portions for both oxygen and carbon.

  2. 18O /16O and 13C /12C in lower Paleozoic articulate brachiopods: Implications for the isotopic composition of seawater

    NASA Astrophysics Data System (ADS)

    Wadleigh, Moire A.; Veizer, Ján

    1992-01-01

    Three hundred and eleven articulate brachiopods, with extensive geographic coverage, spanning the Cambrian to Silurian stratigraphic interval, were analyzed for oxygen and carbon isotopic composition. Cambrian samples have δ18O ≤ -7%., Ordovician samples ≤ -2.4‰, and Silurian samples ≤ -1.9‰, confirming the previously established trend towards lighter isotopic compositions with increasing age throughout the Lower Paleozoic. Forty-nine "best preserved" Ordovician and Silurian samples were identified based on scanning electron microscopy and trace element analysis. They were found to bracket the isotopic compositions of over 85% of specimens from these stratigraphic intervals supporting widespread preservation of the isotopic signal. Some latest Ordovician and Lower Ludlovian samples associated with shale sequences are apparently "enriched" in 18O. These are interpreted as an environmental phenomenon, perhaps related to water temperature and glaciation. A number of Silurian samples of varying genera and stratigraphic levels are highly enriched in 13C, up to +6‰. Some are shale related, but some are associated with carbonate-bearing basins. These are also thought to represent "near-original" compositions, but a single environmental cause is unknown. The present data show that luminescence is not a decisive criterion for evaluating the degree of brachiopod preservation. Whole-shell values were isotopically similar to their nonluminescent portions for both oxygen and carbon.

  3. The non-statistical dynamics of the 18O + 32O2 isotope exchange reaction at two energies

    NASA Astrophysics Data System (ADS)

    Van Wyngarden, Annalise L.; Mar, Kathleen A.; Quach, Jim; Nguyen, Anh P. Q.; Wiegel, Aaron A.; Lin, Shi-Ying; Lendvay, Gyorgy; Guo, Hua; Lin, Jim J.; Lee, Yuan T.; Boering, Kristie A.

    2014-08-01

    The dynamics of the 18O(3P) + 32O2 isotope exchange reaction were studied using crossed atomic and molecular beams at collision energies (Ecoll) of 5.7 and 7.3 kcal/mol, and experimental results were compared with quantum statistical (QS) and quasi-classical trajectory (QCT) calculations on the O3(X1A') potential energy surface (PES) of Babikov et al. [D. Babikov, B. K. Kendrick, R. B. Walker, R. T. Pack, P. Fleurat-Lesard, and R. Schinke, J. Chem. Phys. 118, 6298 (2003)]. In both QS and QCT calculations, agreement with experiment was markedly improved by performing calculations with the experimental distribution of collision energies instead of fixed at the average collision energy. At both collision energies, the scattering displayed a forward bias, with a smaller bias at the lower Ecoll. Comparisons with the QS calculations suggest that 34O2 is produced with a non-statistical rovibrational distribution that is hotter than predicted, and the discrepancy is larger at the lower Ecoll. If this underprediction of rovibrational excitation by the QS method is not due to PES errors and/or to non-adiabatic effects not included in the calculations, then this collision energy dependence is opposite to what might be expected based on collision complex lifetime arguments and opposite to that measured for the forward bias. While the QCT calculations captured the experimental product vibrational energy distribution better than the QS method, the QCT results underpredicted rotationally excited products, overpredicted forward-bias and predicted a trend in the strength of forward-bias with collision energy opposite to that measured, indicating that it does not completely capture the dynamic behavior measured in the experiment. Thus, these results further underscore the need for improvement in theoretical treatments of dynamics on the O3(X1A') PES and perhaps of the PES itself in order to better understand and predict non-statistical effects in this reaction and in the formation

  4. Can tree-ring isotopes18O and δ13C) improve our understanding of hydroclimate variability in the Columbia River Basin?

    NASA Astrophysics Data System (ADS)

    Csank, A. Z.; Wise, E.; McAfee, S. A.

    2015-12-01

    The trajectory of incoming storms from the Pacific Ocean has a strong impact on hydroclimate in the Pacific Northwest. Shifts between zonal and meridional flow are a key influence on drought and pluvial regimes in both the PNW and the western United States as a whole. Circulation-dependent variability in the isotopic composition of precipitation can be recorded and potentially reconstructed using δ18O records derived from tree-rings. Here we present isotopic records of δ18O and δ13C from ponderosa pine (Pinus ponderosa) for the period 1950-2013 from six sites located in the lee of the Cascades in eastern Washington. Because of the orientation of the Cascades, zonal flow will result in an intensified rain shadow whereas meridional flow allows moisture to penetrate at a lower elevation leading to a lower rainout effect. This means zonal flow results in drier conditions in eastern Washington and the converse for meridional flow. We hypothesized that more depleted precipitation δ18O values will occur with periods of more zonal flow across the PNW and will be recorded by trees at our sites. Results show a strong relationship between our δ18O chronologies and winter precipitation (R = -0.50; p<0.001). δ13C chronologies from the same trees showed a relationship to prior fall/winter (pOct-pDec) precipitation (R = -0.46; p<0.005) suggesting a possible link to antecedent moisture conditions. With a focus on years with clear zonal and meridional flow regimes, we regressed the tree-ring δ18O anomaly against the instrumental record of total precipitation and compared the residual series to records of storm track for the period 1978-2008, and we found a detectable signal where the most depleted δ18O was generally associated with zonal flow and the most enriched δ18O with meridional flow. However, there are still some years where the relationship is unclear. Further work is aimed at understanding these anomalous years and extending our record beyond the instrumental

  5. Stable water isotope patterns in a climate change hotspot: the isotope hydrology framework of Corsica (western Mediterranean).

    PubMed

    van Geldern, Robert; Kuhlemann, Joachim; Schiebel, Ralf; Taubald, Heinrich; Barth, Johannes A C

    2014-06-01

    The Mediterranean is regarded as a region of intense climate change. To better understand future climate change, this area has been the target of several palaeoclimate studies which also studied stable isotope proxies that are directly linked to the stable isotope composition of water, such as tree rings, tooth enamel or speleothems. For such work, it is also essential to establish an isotope hydrology framework of the region of interest. Surface waters from streams and lakes as well as groundwater from springs on the island of Corsica were sampled between 2003 and 2009 for their oxygen and hydrogen isotope compositions. Isotope values from lake waters were enriched in heavier isotopes and define a local evaporation line (LEL). On the other hand, stream and spring waters reflect the isotope composition of local precipitation in the catchment. The intersection of the LEL and the linear fit of the spring and stream waters reflect the mean isotope composition of the annual precipitation (δP) with values of-8.6(± 0.2) ‰ for δ(18)O and-58(± 2) ‰ for δ(2)H. This value is also a good indicator of the average isotope composition of the local groundwater in the island. Surface water samples reflect the altitude isotope effect with a value of-0.17(± 0.02) ‰ per 100 m elevation for oxygen isotopes. At Vizzavona Pass in central Corsica, water samples from two catchments within a lateral distance of only a few hundred metres showed unexpected but systematic differences in their stable isotope composition. At this specific location, the direction of exposure seems to be an important factor. The differences were likely caused by isotopic enrichment during recharge in warm weather conditions in south-exposed valley flanks compared to the opposite, north-exposed valley flanks. PMID:24437609

  6. Stable water isotope patterns in a climate change hotspot: the isotope hydrology framework of Corsica (western Mediterranean).

    PubMed

    van Geldern, Robert; Kuhlemann, Joachim; Schiebel, Ralf; Taubald, Heinrich; Barth, Johannes A C

    2014-06-01

    The Mediterranean is regarded as a region of intense climate change. To better understand future climate change, this area has been the target of several palaeoclimate studies which also studied stable isotope proxies that are directly linked to the stable isotope composition of water, such as tree rings, tooth enamel or speleothems. For such work, it is also essential to establish an isotope hydrology framework of the region of interest. Surface waters from streams and lakes as well as groundwater from springs on the island of Corsica were sampled between 2003 and 2009 for their oxygen and hydrogen isotope compositions. Isotope values from lake waters were enriched in heavier isotopes and define a local evaporation line (LEL). On the other hand, stream and spring waters reflect the isotope composition of local precipitation in the catchment. The intersection of the LEL and the linear fit of the spring and stream waters reflect the mean isotope composition of the annual precipitation (δP) with values of-8.6(± 0.2) ‰ for δ(18)O and-58(± 2) ‰ for δ(2)H. This value is also a good indicator of the average isotope composition of the local groundwater in the island. Surface water samples reflect the altitude isotope effect with a value of-0.17(± 0.02) ‰ per 100 m elevation for oxygen isotopes. At Vizzavona Pass in central Corsica, water samples from two catchments within a lateral distance of only a few hundred metres showed unexpected but systematic differences in their stable isotope composition. At this specific location, the direction of exposure seems to be an important factor. The differences were likely caused by isotopic enrichment during recharge in warm weather conditions in south-exposed valley flanks compared to the opposite, north-exposed valley flanks.

  7. Reconstructing lake evaporation history and the isotopic composition of precipitation by a coupled δ18O-δ2H biomarker approach

    NASA Astrophysics Data System (ADS)

    Hepp, Johannes; Tuthorn, Mario; Zech, Roland; Mügler, Ines; Schlütz, Frank; Zech, Wolfgang; Zech, Michael

    2015-10-01

    Over the past decades, δ18O and δ2H analyses of lacustrine sediments became an invaluable tool in paleohydrology and paleolimnology for reconstructing the isotopic composition of past lake water and precipitation. However, based on δ18O or δ2H records alone, it can be challenging to distinguish between changes of the precipitation signal and changes caused by evaporation. Here we propose a coupled δ18O-δ2H biomarker approach that provides the possibility to disentangle between these two factors. The isotopic composition of long chain n-alkanes (n-C25, n-C27, n-C29, n-C31) were analyzed in order to establish a 16 ka Late Glacial and Holocene δ2H record for the sediment archive of Lake Panch Pokhari in High Himalaya, Nepal. The δ2Hn-alkane record generally corroborates a previously established δ18Osugar record reporting on high values characterizing the deglaciation and the Older and the Younger Dryas, and low values characterizing the Bølling and the Allerød periods. Since the investigated n-alkane and sugar biomarkers are considered to be primarily of aquatic origin, they were used to reconstruct the isotopic composition of lake water. The reconstructed deuterium excess of lake water ranges from +57‰ to -85‰ and is shown to serve as proxy for the evaporation history of Lake Panch Pokhari. Lake desiccation during the deglaciation, the Older Dryas and the Younger Dryas is affirmed by a multi-proxy approach using the Hydrogen Index (HI) and the carbon to nitrogen ratio (C/N) as additional proxies for lake sediment organic matter mineralization. Furthermore, the coupled δ18O and δ2H approach allows disentangling the lake water isotopic enrichment from variations of the isotopic composition of precipitation. The reconstructed 16 ka δ18Oprecipitation record of Lake Panch Pokhari is well in agreement with the δ18O records of Chinese speleothems and presumably reflects the Indian Summer Monsoon variability.

  8. Oxygen and Hydrogen Stable Isotope Ratios of Bulk Needles Reveal the Geographic Origin of Norway Spruce in the European Alps

    PubMed Central

    Gori, Yuri; Wehrens, Ron; La Porta, Nicola; Camin, Federica

    2015-01-01

    Background Tracking timber is necessary in order to prevent illegal logging and protect local timber production, but there is as yet no suitable analytical traceability method. Stable isotope ratios in plants are known to reflect geographical variations. In this study we analysed four stable isotope ratios in order to develop a model able to identify the geographic origin of Norway spruce in the European Alps. Methodology and Principal Findings δ18O, δ2H, δ13C and δ15N were measured in bulk needles of Picea abies sampled in 20 sites in and around the European Alps. Environmental and spatial variables were found to be related to the measured isotope ratios. An ordinary least squares regression was used to identify the most important factor in stable isotope variability in bulk needles. Spatial autocorrelation was tested for all isotope ratios by means of Moran’s I. δ18O, δ2H and δ15N values differed significantly between sites. Distance from the coast had the greatest influence on δ2H, while latitude and longitude were strongly related to δ18O. δ13C values did not appear to have any relationship with geographical position, while δ15N values were influenced by distance from the motorway. The regression model improved the explanatory power of the spatial and environmental variables. Positive spatial autocorrelations were found for δ18O and δ2H values. Conclusions The δ 18O, δ2H and δ15N values in P. abies bulk needles are a suitable proxy to identify geographic origin as they vary according to geographical position. Although the regression model showed the explanatory variables to have significant power and stability, we conclude that our model might be improved by multivariate spatial interpolation of the δ 18O and δ2H values. PMID:25742601

  9. Extraction of CO2 from air samples for isotopic analysis and limits to ultra high precision delta18O determination in CO2 gas.

    PubMed

    Werner, R A; Rothe, M; Brand, W A

    2001-01-01

    The determination of delta18O values in CO2 at a precision level of +/-0.02 per thousand (delta-notation) has always been a challenging, if not impossible, analytical task. Here, we demonstrate that beyond the usually assumed major cause of uncertainty - water contamination - there are other, hitherto underestimated sources of contamination and processes which can alter the oxygen isotope composition of CO2. Active surfaces in the preparation line with which CO2 comes into contact, as well as traces of air in the sample, can alter the apparent delta18O value both temporarily and permanently. We investigated the effects of different surface materials including electropolished stainless steel, Duran glass, gold and quartz, the latter both untreated and silanized. CO2 frozen with liquid nitrogen showed a transient alteration of the 18O/16O ratio on all surfaces tested. The time to recover from the alteration as well as the size of the alteration varied with surface type. Quartz that had been ultrasonically cleaned for several hours with high purity water (0.05 microS) exhibited the smallest effect on the measured oxygen isotopic composition of CO2 before and after freezing. However, quartz proved to be mechanically unstable with time when subjected to repeated large temperature changes during operation. After several days of operation the gas released from the freezing step contained progressively increasing trace amounts of O2 probably originating from inclusions within the quartz, which precludes the use of quartz for cryogenically trapping CO2. Stainless steel or gold proved to be suitable materials after proper pre-treatment. To ensure a high trapping efficiency of CO2 from a flow of gas, a cold trap design was chosen comprising a thin wall 1/4" outer tube and a 1/8" inner tube, made respectively from electropolished stainless steel and gold. Due to a considerable 18O specific isotope effect during the release of CO2 from the cold surface, the thawing time had to

  10. Multi-isotope ((15)N, (18)O and (13)C) indicators of sources and fate of nitrate in the upper stream of Chaobai River, Beijing, China.

    PubMed

    Li, Cai; Jiang, Yongbin; Guo, Xinyue; Cao, Yang; Ji, Hongbing

    2014-11-01

    Dual isotopes of nitrate ((15)N and (18)O) and carbon isotopes of dissolved inorganic carbon ((13)C) together with water chemistry were used to identify the sources and fate of nitrate in the upper stream of Chaobai River, north China. The results show that NO3(-) concentrations ranges from 0.03 mmol L(-1) to 0.80 mmol L(-1). Sampling sites from watershed with dominant forest land had higher NO3(-) concentrations and lower δ(15)N-NO3(-) (<10‰) in the wet season than in the dry season, while those from watershed with more anthropogenic activities had lower NO3(-) concentrations and higher δ(15)N-NO3(-) (>10‰) in the wet season. Compositions of isotopes and chemistry indicated that NO3(-) originated mainly from soil N, sewage and livestock wastes and atmospheric nitrogen. Furthermore, the mixing model suggested that soil N was the major NO3(-) source in the wet season, while the sewage and livestock wastes contributed the most in the dry season. Compared to rivers, the Miyun Reservoir had a higher contribution of atmospheric N and the N input from the upper rivers exerted significant influence over the reservoir. Mineralization and nitrification played an important role in N biogeochemistry based on the isotopes ((15)N and (18)O and (13)C) and chemical data. There appeared to be no significant denitrification in the watershed according to the three isotopes and chemical ions. The combined use of (15)N, (18)O and (13)C proved to be useful for further identification of the sources and fate of nitrate in watersheds with dominant forest land in the wet season. PMID:25283837

  11. Nitrogen isotopes as indicators of streamflow generation processes in a headwater forested catchment: Focusing on atmospheric NO3- contribution using δ 18O signature

    NASA Astrophysics Data System (ADS)

    Ohte, N.; Sebestyen, S. D.; Doctor, D. H.; Wankel, S. D.; Shanley, J. B.; Kendall, C.; Boyer, E. W.

    2003-12-01

    To quantify the contributions of atmospheric nitrogen deposition and mechanisms of nitrate discharge to stream, nitrogen chemistry and isotopes (δ 15N and δ 18O of NO3-) of streamwater were studied as part of an ongoing study of nutrient dynamics at the Sleepers River Research Watershed in Vermont, USA. We employed novel analytical procedures for high throughput of NO3- isotopic measurements. The denitrifier method for measurement of δ 15N and δ 18O of NO3- requires a smaller volume of water samples than previously applied methods, thus it enables fine resolution analysis of isotopes for stream, well, and soil water samples. Samples were collected throughout the spring 2003 snowmelt. Snowmelt runoff was initiated in the middle of March and peaked at the end of the month. Then, the runoff rate decreased gradually through April and May, and responded to several storm events. The highest concentration of NO3- in the stream was observed at the beginning of snowmelt (the end of March), and thereafter it declined continuously. The temporal course of NO3- discharge process during snowmelt period was divided into four phases based on changes in the relationship between runoff rate and NO3- concentration. During the earliest phase (very low runoff rate and highest NO3- concentration) isotope signatures, especially δ 18O of NO3-, indicated higher contribution of the atmospherically derived NO3-, meaning that the direct discharge from snow pack was the dominant source of NO3- to the stream. This also suggested that streamwater consisted only of a small volume of groundwater discharge and melt water of the in-stream snow pack and/or stream-covering snow pack. The δ 15N and δ 18O isotope compositions of NO3- during the middle phase of snowmelt indicated that the contribution of the NO3- generated by nitrifiers in soil increased gradually accompanied with increase of groundwater level. These detailed descriptions in the changes of NO3- discharge during snowmelt events

  12. Stable strontium isotope fractionation in synthetic barite

    NASA Astrophysics Data System (ADS)

    Widanagamage, Inoka H.; Schauble, Edwin A.; Scher, Howie D.; Griffith, Elizabeth M.

    2014-12-01

    The mineral barite (BaSO4) accommodates strontium (Sr) in its crystal structure, providing an archive of Sr-isotopes (87Sr/86Sr and δ88/86Sr) in the highly stable sulfate mineral. We investigated mass dependent stable Sr-isotope fractionation (Δ88/86Sr = δ88/86Srsolid - δ88/86Srsolution) during inorganic precipitation of barite from a barium-rich solution by addition of sulfate under controlled conditions and compared this to equilibrium isotopic fractionation calculated using Density Functional Theory modeling. Sr-substituted barite is predicted to have lower 88Sr/86Sr than any other studied species, and at 25 °C will be about 0.6-0.7‰ lower than the two modeled Sr(H2O)82+-bearing salts that could approximate aqueous Sr2+. This agrees in direction and order of magnitude with experimental results that estimate equilibrium Sr-isotope fractionation in barite to be 0.3‰ lower than aqueous Sr2+ at ∼20 °C. The high ionic strength of some of the precipitating solutions (up to 1 M) and potential differences in the average coordination number of aqueous Sr2+ add to uncertainty in a direct comparison of the calculated equilibrium isotopic fractionation values with the experimental results. Stable Sr-isotope fractionation varied along with the distribution coefficient of Sr [Kd(Sr) = [Sr/Ba]barite/[Sr/Ba]solution], which is a function of both temperature and barite saturation state. However the relationship between mass dependent isotopic fractionation and Kd(Sr) is different for conditions of changing temperature versus barite saturation state. With increasing temperature (from 5 to 40 °C), the barite phase became isotopically lighter (Δ88/86Sr = -0.29‰ to -0.41‰). Conversely, with increasing saturation state (saturation index of barite = 3.0-4.3) the barite phase became isotopically heavier (Δ88/86Sr = -0.25‰ to -0.10‰). These observations suggest chemical kinetic effects control isotopic fractionation rather than equilibrium temperature effects. The

  13. Stable isotope enrichment using a plasma centrifuge

    NASA Astrophysics Data System (ADS)

    Krishnan, Mahadevan; Bures, Brian; Madden, Robert

    2012-10-01

    A primary goal of the Department of Energy's Isotope Development and Production for Research and Applications Program (Isotope Program) within the Office of Nuclear Physics (NP) is to produce isotopes that are in short supply in the U.S. and of which there exists no or insufficient domestic commercial production capability. A vacuum arc plasma centrifuge is a rigid rotor column of metal plasma in which centrifugal forces re-distribute ions radially according to their mass/charge ratio. Early work demonstrated rotation at 2 million rpm and separation of various stable isotopes. The spinning plasma column had a Gaussian flux profile, peaked on the rigid rotor axis. This work adopts a more efficient approach, with the plasma created as a hollow column, wherein the flux is concentrated at larger radii where the centrifugal action is highest. By tailoring the vacuum arc discharge geometry, the rotation rate can also be increased to ˜10 million rpm. Data from Cu, Al and other metal plasmas will be presented and discussed in light of enriched stable isotopes needed for research and medicine.

  14. The influence of microclimates and fog on stable isotope signatures used in interpretation of regional hydrology: East Maui, Hawaii

    USGS Publications Warehouse

    Scholl, M.A.; Gingerich, S.B.; Tribble, G.W.

    2002-01-01

    Stable isotopes of precipitation, ground water and surface water measured on the windward side of East Maui from 0 to 3055 m altitude were used to determine recharge sources for stream flow and ground water. Correct interpretation of the hydrology using rainfall ??18O gradients with altitude required consideration of the influence of fog, as fog samples had isotopic signatures enriched by as much as 3??? in ??18O and 21??? in ??D compared to volume-weighted average precipitation at the same altitude. The isotopic analyses suggested that fog drip was a major component of stream flow and shallow ground water at higher altitudes in the watershed. 18O/altitude gradients in rainfall were comparable for similar microclimates on Maui (this study) and Hawaii Island (1990-1995 study), however, East Maui ??18O values for rain in trade-wind and high-altitude microclimates were enriched compared to those from Hawaii Island. Isotopes were used to interpret regional hydrology in this volcanic island aquifer system. In part of the study area, stable isotopes indicate discharge of ground water recharged at least 1000 m above the sample site. This deep-flowpath ground water was found in springs from sea level up to 240 m altitude, indicating saturation to altitudes much higher than a typical freshwater lens. These findings help in predicting the effects of ground water development on stream flow in the area. Published by Elsevier Science B.V.

  15. Stable isotope estimates of evaporation: inflow and water residence time for lakes across the United States as a tool for national lake water quality assessments

    EPA Science Inventory

    Stable isotope ratios of water (delta18O and delta2H) can be very useful in large-scale monitoring programs because water samples are easy to collect and isotope ratios integrate information about basic hydrologic processes such as evaporation as a percentage of inflow (E/I) and ...

  16. Paired stable isotopes (O, C) and clumped isotope thermometry of magnesite and silica veins in the New Caledonia Peridotite Nappe

    NASA Astrophysics Data System (ADS)

    Quesnel, Benoît; Boulvais, Philippe; Gautier, Pierre; Cathelineau, Michel; John, Cédric M.; Dierick, Malorie; Agrinier, Pierre; Drouillet, Maxime

    2016-06-01

    The stable isotope compositions of veins provide information on the conditions of fluid-rock interaction and on the origin of fluids and temperatures. In New Caledonia, magnesite and silica veins occur throughout the Peridotite Nappe. In this work, we present stable isotope and clumped isotope data in order to constrain the conditions of fluid circulation and the relationship between fluid circulation and nickel ore-forming laterization focusing on the Koniambo Massif. For magnesite veins occurring at the base of the nappe, the high δ18O values between 27.8‰ and 29.5‰ attest to a low temperature formation. Clumped isotope analyses on magnesite give temperatures between 26 °C and 42 °C that are consistent with amorphous silica-magnesite oxygen isotope equilibrium. The meteoric origin of the fluid is indicated by calculated δ18Owater values between -3.4‰ to +1.5‰. Amorphous silica associated with magnesite or occurring in the coarse saprolite level displays a narrow range of δ18O values between 29.7‰ and 35.3‰. For quartz veins occurring at the top of the bedrock and at the saprolite level, commonly in association with Ni-talc-like minerals, the δ18O values are lower, between 21.8‰ and 29.0‰ and suggest low-temperature hydrothermal conditions (∼40-95 °C). Thermal equilibration of the fluid along the geothermic gradient before upward flow through the nappe and/or influence of exothermic reactions of serpentinization could be the source(s) of heat needed to form quartz veins under such conditions.

  17. Archaean fluid-assisted crustal cannibalism recorded by low δ18O and negative ɛHf(T) isotopic signatures of West Greenland granite zircon

    NASA Astrophysics Data System (ADS)

    Hiess, Joe; Bennett, Vickie C.; Nutman, Allen P.; Williams, Ian S.

    2011-06-01

    The role of fluids during Archaean intra-crustal magmatism has been investigated via integrated SHRIMP U-Pb, δ18O and LA-MC-ICPMS 176Hf isotopic zircon analysis. Six rock samples studied are all from the Nuuk region (southern West Greenland) including two ~3.69 Ga granitic and trondhjemitic gneisses, a 3.64 Ga granitic augen gneiss, a 2.82 Ga granodioritic Ikkattoq gneiss, a migmatite with late Neoarchaean neosome and a homogeneous granite of the 2.56 Ga Qôrqut Granite Complex (QGC). All zircon grains were thoroughly imaged to facilitate analysis of magmatic growth domains. Within the zircon analysed, there is no evidence for metamictization. Initial ɛHf zircon values ( n = 63) are largely sub-chondritic, indicating the granitic host magmas were generated by the remelting of older, un-radiogenic crustal components. Zircon from some granite samples displays more than one 207Pb/206Pb age, and correlated with 176Hf/177Hf compositions can trace multiple phases of remelting or recrystallization during the Archaean. Model ages calculated using Lu/Hf arrays for each sample indicate that the crustal parental rocks to the granites, granodiorites and trondhjemites segregated from a chondrite-like reservoir at an earlier time during the Archaean, corresponding to known formation periods of more primitive tonalite-trondhjemite-granodiorite (TTG) gneisses. Zircon from the ~3.69 Ga granite, the migmatite and QGC granite contains Eoarchaean cores with chondritic 176Hf/177Hf and mantle-like δ18O compositions. The age and geochemical signatures from these inherited components are identical to those of surrounding tonalitic gneisses, further suggesting genesis of these granites by remelting of broadly tonalitic protoliths. Zircon oxygen isotopic compositions ( n = 62) over nine age populations (six igneous and three inherited) have weighted mean or mean δ18O values ranging from 5.8 ± 0.6 to 3.7 ± 0.5‰. The 3.64 Ga granitic augen gneiss sample displays the highest δ18O with

  18. Links between purchase location and stable isotope ratios of bottled water, soda, and beer in the United States.

    PubMed

    Chesson, Lesley A; Valenzuela, Luciano O; O'Grady, Shannon P; Cerling, Thure E; Ehleringer, James R

    2010-06-23

    This study investigated the impact of purchase location on the stable isotope ratios of beverages by measuring the delta(2)H and delta(18)O values of bottled water, soda, beer, and tap water collected across the contiguous United States. Measured beverage delta(2)H and delta(18)O values generally fit the Global Meteoric Water Line (GMWL), suggesting region-of-origin information is recorded in beverage water. Tap water delta(2)H and delta(18)O values were strongly correlated with the stable isotope ratios of bottled water and soda purchased in the same location. Beer water delta(2)H and delta(18)O values were also correlated with tap water, although not as strongly. Variability in delta(2)H and delta(18)O values among beverages purchased at a single location ranged from 2 to 41 per thousand and from 0.3 to 5.2 per thousand, respectively, but was generally moderate in most locations. It was concluded that the isotopic composition of local tap water is a reasonable proxy for consumers' fluid intake in most U.S. cities.

  19. Chemical weathering and the role of sulfuric and nitric acids in carbonate weathering: Isotopes (13C, 15N, 34S, and 18O) and chemical constraints

    NASA Astrophysics Data System (ADS)

    Li, Cai; Ji, Hongbing

    2016-05-01

    Multiple isotopes (13C-DIC, 34S and 18O-SO42-, 15N and 18O-NO3-) and water chemistry were used to evaluate weathering rates and associated CO2 consumption by carbonic acid and strong acids (H2SO4 and HNO3) in a typical karst watershed (Wujiang River, Southwest China). The dual sulfate isotopes indicate that sulfate is mainly derived from sulfide oxidation in coal stratum and sulfide-containing minerals, and dual nitrate isotopes indicate that nitrate is mainly derived from soil N and nitrification. The correlation between isotopic compositions and water chemistry suggests that sulfuric and nitric acids, in addition to carbonic acid, are involved in carbonate weathering. The silicate and carbonate weathering rates are 7.2 t km-2 yr-1 and 76 t km-2 yr-1, respectively. In comparison with carbonate weathering rates (43 t km-2 yr-1) by carbonic acid alone, the subsequent increase in rates indicates significant enhancement of weathering when combined with sulfuric and nitric acids. Therefore, the role of sulfuric and nitric acids in the rock weathering should be considered in the global carbon cycle.

  20. Do Speleothem Stable Isotope Records Contain Hidden Tropical Cyclone Histories? Exploring C-O Isotope Correlation Patterns for Indicators of Tropical Cyclone Masking

    NASA Astrophysics Data System (ADS)

    Frappier, A. E.; Rossington, C.

    2013-12-01

    The newly-described tropical cyclone masking effect on stable isotope paleohydrological signals in speleothem records arises from the intermittent delivery of large pulses of isotopically distinct tropical cyclone rain. Recent work shows that 18-O depleted tropical cyclone stormwater depresses the δ18O value of speleothem calcite for months to years following a tropical cyclone event, masking the background stable isotope signal of persistent climate variability. Periods of high local storm activity can lead to speleothem calcite paleohydrological signals with significant wet biases on interannual to decadal timescales. Because speleothem carbon isotope ratios are independent of tropical cyclone rainfall, tropical speleothems are known to exhibit moderate C-O isotope covariation over time, periods when C-O isotope covariation breaks down and δ18O values are low may provide a marker for times when tropical cyclone masking is important. If so, existing speleothem stable isotope records from tropical cyclone-prone regions may contain signatures of tropical cyclone masking in the temporal evolution of C-O isotope covariation patterns. We present results from an exploratory analysis of several published speleothem records that are candidates for containing tropical cyclone masking signals. For each speleothem, overall C-O isotope covariation coefficients were calculated, and transient covariation patterns were analyzed using a sliding correlation index, the Covariation of Stable Isotopes (CoSI) index, and Local Correlation (LoCo). Local tropical cyclone historical and paleotempest records are compared and a method is presented to test for the presence of tropical cyclone masking intervals. The implications for speleothem paleoclimatology and paleotempestology are discussed.

  1. Fractionation of stable isotopes in perchlorate and nitrate during in situ biodegradation in a sandy aquifer

    USGS Publications Warehouse

    Hatzinger, P.B.; Böhlke, J.K.; Sturchio, N.C.; Gu, B.; Heraty, L.J.; Borden, R.C.

    2009-01-01

    Environmental context. Perchlorate (ClO4-) and nitrate (NO3-) are common co-contaminants in groundwater, with both natural and anthropogenic sources. Each of these compounds is biodegradable, so in situ enhanced bioremediation is one alternative for treating them in groundwater. Because bacteria typically fractionate isotopes during biodegradation, stable isotope analysis is increasingly used to distinguish this process from transport or mixing-related decreases in contaminant concentrations. However, for this technique to be useful in the field to monitor bioremediation progress, isotope fractionation must be quantified under relevant environmental conditions. In the present study, we quantify the apparent in situ fractionation effects for stable isotopes in ClO4- (Cl and O) and NO3- (N and O) resulting from biodegradation in an aquifer. Abstract. An in situ experiment was performed in a shallow alluvial aquifer in Maryland to quantify the fractionation of stable isotopes in perchlorate (Cl and O) and nitrate (N and O) during biodegradation. An emulsified soybean oil substrate that was previously injected into this aquifer provided the electron donor necessary for biological perchlorate reduction and denitrification. During the field experiment, groundwater extracted from an upgradient well was pumped into an injection well located within the in situ oil barrier, and then groundwater samples were withdrawn for the next 30 h. After correction for dilution (using Br- as a conservative tracer of the injectate), perchlorate concentrations decreased by 78% and nitrate concentrations decreased by 82% during the initial 8.6 h after the injection. The observed ratio of fractionation effects of O and Cl isotopes in perchlorate (18O/37Cl) was 2.6, which is similar to that observed in the laboratory using pure cultures (2.5). Denitrification by indigenous bacteria fractionated O and N isotopes in nitrate at a ratio of ???0.8 (18O/15N), which is within the range of values

  2. The use of stable isotopes in quantitative determinations of exogenous water and added ethanol in wines

    NASA Astrophysics Data System (ADS)

    Magdas, D. A.; Moldovan, Z.; Cristea, G.

    2012-02-01

    The application of oxygen isotope ratios analysis to wine water according to EU regulation no. 822/97 to determine wine's origin and also, the possible water addition to wines, gained great importance in wines authenticity control. In the natural cycle of water isotopic fractionation, during water evaporation process, the water vapors are depleted in heavy isotopes. On the other hand inside the plants take place an isotope enrichment of heavy stable isotopes of water compared with meteoric water due to photosynthesis and plants transpiration. This process makes possible the detection of exogenous water from wines 18O/16O ratios. Carbon isotopic ratios were used to estimate the supplementary addition of ethanol obtained from C4 plants (sugar cane or corn). This work presents the way in which the isotopic fingerprints (δ13C and δ18O) were used to determine the content of exogenous water from wines and the added supplementary ethanol coming from C4 plants. By using this method, the calculated values obtained for the degree of wine adulteration were in a good agreement with the real exogenous percent of water and ethanol from investigated samples.

  3. Proton tunnelling in the hydrogen bonds of the benzoic acid dimer: (18)O substitution and isotope effects of the heavy atom framework.

    PubMed

    Frantsuzov, I; Johnson, M R; Trommsdorff, H P; Horsewill, A J

    2014-07-17

    Field-cycling (1)H NMR relaxometry has been used to measure the rate of concerted double proton transfer in the hydrogen bonds of (16)O and (18)O isotopologues of benzoic acid dimers. The experiments have been conducted in the solid state at low temperature 13.3 ≤ T ≤ 80 K where the dynamics are dominated by incoherent proton tunnelling. The low temperature tunnelling rate in the (16)O isotopologue is observed to be approximately 15% faster than in the (18)O isotopologue. The difference is attributed to an isotope effect of the heavy atom framework of the benzoic acid dimer resulting from displacements of the oxygen atoms that accompany the proton transfer. Sources of systematic uncertainty have been minimized in the design of the experimental protocols and the experiments are critically appraised in formally assigning the measured differences to an effect of mass on the tunnelling dynamics.

  4. Plan of study to determine if the isotopic ratios [delta]15 N and [delta]18 O can reveal the sources of nitrate discharged by the Mississippi River into the Gulf of Mexico

    USGS Publications Warehouse

    Battaglin, William A.; Kendall, Carol; Goolsby, Donald A.; Boyer, Laurie L.

    1997-01-01

    Nitrate and other nutrients discharged from the Mississippi River basin are suspected of causing a zone of depleted dissolved oxygen (hypoxic zone) in the Gulf of Mexico each summer. The hypoxic zone may have an adverse effect on aquatic life and commercial fisheries. Commercial fertilizers are the dominant source of nitrogen input to the Mississippi basin. Other nitrogen sources include animal waste, fixation of atmospheric nitrogen by legumes, precipitation, domestic and industrial effluent, and the soil. The inputs of nitrogen from most of these sources to the Mississippi basin can be estimated and the outputs in surface water can be measured. However, nitrogen from each source is affected differently by physical, chemical, and biological processes that control nitrogen cycling in terrestrial and aquatic systems. Hence, the relative contributions from the various sources of nitrogen to nitrate load in the Mississippi River are unknown because the different sources may not contribute proportionally to their inputs in the basin. It may be possible to determine the relative contributions of the major sources of nitrate in river water using the stable isotopic ratios d15N and d18O of the nitrate ion. A few researchers have used the d15N and/or d18O isotope ratios to determine sources of nitrate in ground water, headwater catchments, and small rivers, but little is known about the isotopic composition of nitrate in larger rivers. The objective of this study is to measure the isotopic composition of nitrate and suspended organic matter in the Mississippi River and its major tributaries, in discharge to the Gulf of Mexico, and in streamflow from smaller watersheds that have distinct sources of nitrogen (row crops, animal wastes, and urban effluents) or are minimally impacted by man (undeveloped). Samples from seven sites on the Mississippi River and its tributaries and from 17 sites in smaller watersheds within the Mississippi River basin will be analyzed for d15N and

  5. Coordinated Isotopic and Mineral Characterization of Highly Fractionated 18O-Rich Silicates in the Queen Alexandra Range 99177 CR3 Chondrite

    NASA Technical Reports Server (NTRS)

    Nguyen, A. N.; Keller, L. P.; Messenger, S.; Rahman, Z.

    2016-01-01

    Carbonaceous chondrites contain a mixture of solar system condensates, pre-solar grains, and primitive organic matter. Each of these materials record conditions and processes in different regions of the solar nebula, on the meteorite parent body, and beyond the solar system. Oxygen isotopic studies of meteorite components can trace interactions of distinct oxygen isotopic reservoirs in the early solar system and secondary alteration processes. The O isotopic compositions of the earliest solar system condensates fall along a carbonaceous chondrite anhydrous mineral (CCAM) line of slope approximately 1 in a plot of delta 17O against delta 18O. This trend is attributed to mixing of material from 16O-poor and 16O-rich reservoirs. Secondary processing can induce mass-dependent fractionation of the O isotopes, shifting these compositions along a line of slope approximately 0.52. Substantial mass-dependent fractionation of O isotopes has been observed in secondary minerals in CAIs, calcite, and FUN inclusions. These fractionations were caused by significant thermal or aqueous alteration. We recently reported the identification of four silicate grains with extremely fractionated O isotopic ratios (delta 18O equals 37 - 55 per mille) in the minimally altered CR3 chondrite QUE 99177. TEM analysis of one grain indicates it is a nebular condensate that did not experience substantial alteration. The history of these grains is thus distinct from those of the aforementioned fractionated materials. To constrain the origin of the silicate grains, we conducted further Mg and Fe isotopic studies and TEM analyses of two grains.

  6. Sm-Nd, Rb-Sr, and /sup 18/O//sup 16/O isotopic systematics in an oceanic crustal section: Evidence from the Samial ophiolite

    SciTech Connect

    McCulloch, M.T.; Gregory, R.T.; Wasserburg, G.J.; Taylor, H.P. Jr.

    1981-04-10

    The Sm-Nd, Rb-Sr, and /sup 18/O//sup 16/O isotopic systems have been used to distinguish between the effects of seafloor hydrothermal alteration and primary magmatic isotopic variations. The Sm-Nd isotopic system is essentially unaffected by seawater alteration, while the Rb-Sr and /sup 18/O//sup 16/O systems are sensitive to hydrothermal interactions with seawater. Sm-Nd mineral isochrons from the cumulate gabbros of the Samail ophiolite have an initial /sup 143/Nd//sup 144/Nd ratio of e/sub Nd/ = 7.8 +- 0.3, which clearly substantiates the oceanic affinity of this complex. The initial /sup 143/Nd//sup 144/Nd ratios for the harzburgite, plagiogranite, sheeted diabase dikes, and basalt units have a limited range in e/sub Nd/ of from 7.5 to 8.6, indicating that all the lithologies have distinctive oceanic affinities, although there is also some evidence for small isotopic heterogeneities in the magma reservoirs. The Sm-Nd mineral isochrons give crystallization ages of 128 +- 20 m.y. and 150 +- 40 m.y. from Ibra and 100 +- 20 m.y. from Wadi Fizh, which is approximately 300 km NW of Ibra. These crystallization ages are interpreted as the time of formation of the oceanic crust. The /sup 87/Sr//sup 86/Sr initial ratios on the same rocks have an extremely large range of from 0.7030 to 0.7065 and the d/sup 18/O values vary from 2.6 to 12.7. These large variations clearly demonstrate hydrothermal interaction of oceanic crust with seawater.

  7. [Stable Isotope Characteristics in Different Water Bodies in Changsha and Implications for the Water Cycle].

    PubMed

    Li, Guang; Zhang, Xin-ping; Zhang, Li-feng; Wang, Yue-feng; Deng, Xiao-jun; Yang, Liu; Lei, Chao-gui

    2015-06-01

    Analysis of the variation characteristics of different water bodies is the basis of applying isotopic tracer technique in regional water cycle research. Based on the samples of atmospheric precipitation, surface water (river water) and groundwater (spring water and well water) in Changsha from January 2012 to December 2013, the study analyzed the variation characteristics of δD and δ(18)O in different water bodies. The results showed that the values of D and 18O in precipitation of Changsha showed obvious seasonal variation because of the seasonal difference of the water vapor source, and it showed significant negative correlation between δ(18)O in precipitation and some meteorological factors such as the temperature and the amount, the local meteoric water line revealed the climatic characteristic of humid and rainy in Changsha; the fluctuation of 8D and 80 in surface water was more moderate than those in precipitation, and the seasonal variation of stable isotope value showed lagging characteristic compared with that in precipitation, the difference of river water line (RWL) indicated that the main supply sources of surface water were changing in different seasons; the fluctuation of δD and δ(18)O in groundwater was the least, the variation ranges and mean values of δD and δ(18)O in spring water and well water were very close, it showed that there were some hydraulic connections in the two water bodies, the values of δD and δ(18)O in groundwater were constantly lower during drought months, this phenomenon might have a certain relationship with the increasing absorbency of tree roots from groundwater. The results of the study have certain guiding significance for rational utilization of water resources in the region. PMID:26387312

  8. Oxygen isotopes in Indian Plate eclogites (Kaghan Valley, Pakistan): Negative δ18O values from a high latitude protolith reset by Himalayan metamorphism

    NASA Astrophysics Data System (ADS)

    Rehman, Hafiz Ur; Tanaka, Ryoji; O'Brien, Patrick J.; Kobayashi, Katsura; Tsujimori, Tatsuki; Nakamura, Eizo; Yamamoto, Hiroshi; Khan, Tahseenullah; Kaneko, Yoshiyuki

    2014-11-01

    Oxygen isotope compositions are reported for the first time for the Himalayan metabasites of the Kaghan Valley, Pakistan in this study. The highest metamorphic grades are recorded in the north of the valley, near the India-Asia collision boundary, in the form of high-pressure (HP: Group I) and ultrahigh-pressure (UHP: Group II) eclogites. The rocks show a step-wise decrease in grade from the UHP to HP eclogites and amphibolites. The protoliths of these metabasites were the Permian Panjal Trap basalts (ca. 267 ± 2.4 Ma), which were emplaced along the northern margin of India when it was part of Gondwana. After the break-up of Gondwana, India drifted northward, subducted beneath Asia and underwent UHP metamorphism during the Eocene (ca. 45 ± 1.2 Ma). At the regional scale, amphibolites, Group I and II eclogites yielded δ18O values of + 5.84 and + 5.91‰, + 1.66 to + 4.24‰, and - 2.25 to + 0.76‰, respectively, relative to VSMOW. On a more local scale, within a single eclogite body, the δ18O values were the lowest (- 2.25 to- 1.44‰) in the central, the best preserved (least retrograded) parts, and show a systematic increase outward into more retrograded rocks, reaching up to + 0.12‰. These values are significantly lower than the typical mantle values for basalts of + 5.7 ± 0.3‰. The unusually low or negative δ18O values in Group II eclogites potentially resulted from hydrothermal alteration of the protoliths by interactions with meteoric water when the Indian plate was at southern high latitudes (~ 60°S). The stepwise increase in δ18O values, among different eclogite bodies in general and at single outcrop-scales in particular, reflects differing degrees of resetting of the oxygen isotope compositions during exhumation-related retrogression.

  9. Eocene-Oligocene proto-Cascades topography revealed by clumped (Δ47) and oxygen isotope18O) geochemistry (Chumstick Basin, WA, USA)

    NASA Astrophysics Data System (ADS)

    Methner, Katharina; Fiebig, Jens; Wacker, Ulrike; Umhoefer, Paul; Chamberlain, C. Page; Mulch, Andreas

    2016-03-01

    The topography of the present-day Washington Cascades impacts atmospheric circulation and precipitation patterns in the Pacific Northwest, introducing a pronounced orographic rain shadow in the lee of the mountain range. The temporal development of Cascade topography, however, remains largely unconstrained for the early Cenozoic. Based on coupled carbonate clumped isotope (Δ47) and oxygen isotope18O) measurements we reconstruct δ18O values of Eocene groundwater (δ18Owater) in the Chumstick basin (central Washington), today located in the Cascade rain shadow. Δ47 (paleo)thermometry indicates a systematic change in basin burial temperatures from 110°C to 70°C depending on burial depth in the basin. These data are in good agreement with low-T thermochronological and vitrinite reflectance data, and further constrain the basin burial and exhumation history. In concert with field observations, microstructural analysis, and δ18O values of the analyzed carbonates, we suggest that the Δ47 temperatures and δ18O values reflect open-system carbonate cement recrystallization in meteoric-derived groundwaters during early burial diagenesis. Assuming open-system behavior, reconstructed mean δ18Owater values of ~ -7‰ (middle Eocene) to -9‰ (late Eocene/early Oligocene) are consistent with a low-elevation origin of the corresponding meteoric waters that permeated the sandstone/conglomerate members of the Eocene sedimentary units. In light of the paleogeographic setting of the Chumstick basin, the reconstructed δ18Owater values agree well with Pacific-derived moisture that did not experience strong rainout. The absence of a rain shadow effect therefore permits only moderate Eocene/Oligocene elevations at least for the southern part of the Washington proto-Cascades.

  10. δ13C and δ18O isotopic composition of CaCO3 measured by continuous flow isotope ratio mass spectrometry: statistical evaluation and verification by application to Devils Hole core DH-11 calcite

    USGS Publications Warehouse

    Revesz, Kinga M.; Landwehr, Jurate M.

    2002-01-01

    A new method was developed to analyze the stable carbon and oxygen isotope ratios of small samples (400 ± 20 µg) of calcium carbonate. This new method streamlines the classical phosphoric acid/calcium carbonate (H3PO4/CaCO3) reaction method by making use of a recently available Thermoquest-Finnigan GasBench II preparation device and a Delta Plus XL continuous flow isotope ratio mass spectrometer. Conditions for which the H3PO4/CaCO3 reaction produced reproducible and accurate results with minimal error had to be determined. When the acid/carbonate reaction temperature was kept at 26 °C and the reaction time was between 24 and 54 h, the precision of the carbon and oxygen isotope ratios for pooled samples from three reference standard materials was ≤0.1 and ≤0.2 per mill or ‰, respectively, although later analysis showed that materials from one specific standard required reaction time between 34 and 54 h for δ18O to achieve this level of precision. Aliquot screening methods were shown to further minimize the total error. The accuracy and precision of the new method were analyzed and confirmed by statistical analysis. The utility of the method was verified by analyzing calcite from Devils Hole, Nevada, for which isotope-ratio values had previously been obtained by the classical method. Devils Hole core DH-11 recently had been re-cut and re-sampled, and isotope-ratio values were obtained using the new method. The results were comparable with those obtained by the classical method with correlation = +0.96 for both isotope ratios. The consistency of the isotopic results is such that an alignment offset could be identified in the re-sampled core material, and two cutting errors that occurred during re-sampling then were confirmed independently. This result indicates that the new method is a viable alternative to the classical reaction method. In particular, the new method requires less sample material permitting finer resolution and allows

  11. A stable isotope approach and its application for identifying nitrate source and transformation process in water.

    PubMed

    Xu, Shiguo; Kang, Pingping; Sun, Ya

    2016-01-01

    Nitrate contamination of water is a worldwide environmental problem. Recent studies have demonstrated that the nitrogen (N) and oxygen (O) isotopes of nitrate (NO3(-)) can be used to trace nitrogen dynamics including identifying nitrate sources and nitrogen transformation processes. This paper analyzes the current state of identifying nitrate sources and nitrogen transformation processes using N and O isotopes of nitrate. With regard to nitrate sources, δ(15)N-NO3(-) and δ(18)O-NO3(-) values typically vary between sources, allowing the sources to be isotopically fingerprinted. δ(15)N-NO3(-) is often effective at tracing NO(-)3 sources from areas with different land use. δ(18)O-NO3(-) is more useful to identify NO3(-) from atmospheric sources. Isotopic data can be combined with statistical mixing models to quantify the relative contributions of NO3(-) from multiple delineated sources. With regard to N transformation processes, N and O isotopes of nitrate can be used to decipher the degree of nitrogen transformation by such processes as nitrification, assimilation, and denitrification. In some cases, however, isotopic fractionation may alter the isotopic fingerprint associated with the delineated NO3(-) source(s). This problem may be addressed by combining the N and O isotopic data with other types of, including the concentration of selected conservative elements, e.g., chloride (Cl(-)), boron isotope (δ(11)B), and sulfur isotope (δ(35)S) data. Future studies should focus on improving stable isotope mixing models and furthering our understanding of isotopic fractionation by conducting laboratory and field experiments in different environments.

  12. A stable isotope approach and its application for identifying nitrate source and transformation process in water.

    PubMed

    Xu, Shiguo; Kang, Pingping; Sun, Ya

    2016-01-01

    Nitrate contamination of water is a worldwide environmental problem. Recent studies have demonstrated that the nitrogen (N) and oxygen (O) isotopes of nitrate (NO3(-)) can be used to trace nitrogen dynamics including identifying nitrate sources and nitrogen transformation processes. This paper analyzes the current state of identifying nitrate sources and nitrogen transformation processes using N and O isotopes of nitrate. With regard to nitrate sources, δ(15)N-NO3(-) and δ(18)O-NO3(-) values typically vary between sources, allowing the sources to be isotopically fingerprinted. δ(15)N-NO3(-) is often effective at tracing NO(-)3 sources from areas with different land use. δ(18)O-NO3(-) is more useful to identify NO3(-) from atmospheric sources. Isotopic data can be combined with statistical mixing models to quantify the relative contributions of NO3(-) from multiple delineated sources. With regard to N transformation processes, N and O isotopes of nitrate can be used to decipher the degree of nitrogen transformation by such processes as nitrification, assimilation, and denitrification. In some cases, however, isotopic fractionation may alter the isotopic fingerprint associated with the delineated NO3(-) source(s). This problem may be addressed by combining the N and O isotopic data with other types of, including the concentration of selected conservative elements, e.g., chloride (Cl(-)), boron isotope (δ(11)B), and sulfur isotope (δ(35)S) data. Future studies should focus on improving stable isotope mixing models and furthering our understanding of isotopic fractionation by conducting laboratory and field experiments in different environments. PMID:26541149

  13. Evidence of the chemical reaction of (18)O-labelled nitrite with CO2 in aqueous buffer of neutral pH and the formation of (18)OCO by isotope ratio mass spectrometry.

    PubMed

    Tsikas, Dimitrios; Böhmer, Anke; Gros, Gerolf; Endeward, Volker

    2016-05-01

    Inorganic nitrite (NO2(-), ON-O(-) ←→ (-)O-NO) is the autoxidation product of nitric oxide (NO). Nitrite can also be formed from inorganic nitrate (ONO2(-)), the major oxidation product of NO in erythrocytes, by the catalytic action of bacterial nitrate reductase in gut and oral microflora. Nitrite can be reduced to NO by certain cellular proteins and enzymes, as well as in the gastric juice under acidic conditions. Hemoglobin, xanthine oxidoreductase and carbonic anhydrase (CA) have been reported to convert nitrite to NO. Renal CA isoforms are involved in the reabsorption of nitrite and may, therefore, play an important role in NO homeostasis. Yet, the mechanisms underlying the action of CA on nitrite are incompletely understood. The nitrate/nitrite system is regarded as a reservoir of NO. We have recently shown that nitrite reacts chemically with carbon dioxide (CO2), the regular substrate of CA. The present communication reports a stable isotope ratio mass spectrometry (IRMS) study on the reaction of NO2(-) and CO2 performed in 50 mM HEPES buffer of pH 7.4 at 37 °C. By using (18)O-labelled nitrite ((18)ON-O(-)/(-18)O-NO) and CO2 we observed formation of (18)O-labelled CO2. This finding is an unequivocal evidence of the chemical reaction of (18)ON-O(-)/(-18)O-NO with CO2. The reaction is rapid and involves nucleophilic attack of the negatively charged nitrite via one of its oxygen atoms on the partially positively charged CO2 molecule to form the putative intermediate (18)ON-O-CO2(-)/(-)O2C-(18)O-NO. The by far largest fraction of this intermediate decomposes back to (18)ON-O(-)/(-18)O-NO and CO2. A very small fraction of the intermediate, however, rearranges and finally decomposes to form (18)OCO and nitrite. This reaction is slower in the presence of an isolated erythrocytic CA isoform II. In summary, NO2(-), CO2 and CA are ubiquitous. The chemical reaction of NO2(-) with CO2 and its modulation by CA isoforms may play important roles in the transport of

  14. Tungsten Stable Isotope Compositions of Ferromanganese Crusts

    NASA Astrophysics Data System (ADS)

    Abraham, K.; Barling, J.; Hein, J. R.; Schauble, E. A.; Halliday, A. N.

    2014-12-01

    We report the first accurate and precise data for mass-dependent fractionation of tungsten (W) stable isotopes, using a double spike technique and MC-ICPMS. Results are expressed relative to the NIST 3136 W isotope standard as per mil deviations in 186W/184W (δ186W). Although heavy element mass-dependent fractionations are expected to be small, Tl and U both display significant low temperature isotopic fractionations. Theoretical calculations indicate that W nuclear volume isotopic effects should be smaller than mass-dependent fractionations at low temperatures. Hydrogenetic ferromanganese (Fe-Mn) crusts precipitate directly from seawater and have been used as paleoceanographic recorders of temporal changes in seawater chemistry. Crusts are strongly enriched in W and other metals, and are a promising medium for exploring W isotopic variability. Tungsten has a relatively long residence time in seawater of ~61,000 years, mainly as the tungstate ion (WO42-). Water depth profiles show conservative behaviour. During adsorption on Fe-Mn crusts, W species form inner-sphere complexes in the hexavalent (W6+) state. The major host phase is thought to be Mn oxides and the lighter W isotope is expected to be absorbed preferentially. Surface scrapings of 13 globally distributed hydrogenetic Fe-Mn crusts display δ186W from -0.08 to -0.22‰ (±0.03‰, 2sd). A trend toward lighter W isotope composition exists with increasing water depth (~1500 to ~5200m) and W concentration. One hydrothermal Mn-oxide sample is anomalously light and Mn nodules are both heavy and light relative to Fe-Mn crusts. Tungsten speciation depends on concentration, pH, and time in solution and is not well understood because of the extremely slow kinetics of the reactions. In addition, speciation of aqueous and/or adsorbed species might be sensitive to pressure, showing similar thermodynamic stability but different effective volumes. Thus, W stable isotopes might be used as a water-depth barometer in

  15. Long-term and high frequency non-destructive monitoring of water stable isotope profiles in an evaporating soil column

    NASA Astrophysics Data System (ADS)

    Rothfuss, Y.; Merz, S.; Vanderborght, J.; Hermes, N.; Weuthen, A.; Pohlmeier, A.; Vereecken, H.; Brüggemann, N.

    2015-04-01

    The stable isotope compositions of soil water (δ2H and δ18O) carry important information about the prevailing soil hydrological conditions and for constraining ecosystem water budgets. However, they are highly dynamic, especially during and after precipitation events. The classical method of determining soil water δ2H and δ18O at different depths, i.e., soil sampling and cryogenic extraction of the soil water, followed by isotope-ratio mass spectrometer analysis is destructive and laborious with limited temporal resolution. In this study, we present a new non-destructive method based on gas-permeable tubing and isotope-specific infrared laser absorption spectroscopy. We conducted a laboratory experiment with an acrylic glass column filled with medium sand equipped with gas-permeable tubing at eight different soil depths. The soil column was initially saturated from the bottom, exposed to evaporation for a period of 290 days, and finally rewatered. Soil water vapor δ2H and δ18O were measured daily, sequentially for each depth. Soil liquid water δ2H and δ18O were inferred from the isotopic values of the vapor assuming thermodynamic equilibrium between liquid and vapor phases in the soil. The experimental setup allowed following the evolution of typical exponential-shaped soil water δ2H and δ18O profiles with unprecedentedly high temporal resolution. As the soil dried out, we could also show for the first time the increasing influence of the isotopically depleted ambient water vapor on the isotopically enriched liquid water close to the soil surface (i.e., atmospheric invasion). Rewatering at the end of the experiment led to instantaneous resetting of the stable isotope profiles, which could be closely followed with the new method.

  16. Fractionation of stable isotopes in perchlorate and nitrate during in situ biodegradation in a sandy aquifer

    SciTech Connect

    Hatzinger, Paul B.; Bohlke, J. K.; Sturchio, N. C.; Gu, Baohua

    2009-01-01

    An in situ experiment was performed in a shallow alluvial aquifer in Maryland to quantify the fractionation of stable isotopes in perchlorate (Cl and O) and nitrate (N and O) during biodegradation. An emulsified soybean oil substrate that was previously injected into this aquifer provided the electron donor necessary for biological perchlorate reduction and denitrification. During the field experiment, groundwater extracted from an upgradient well was pumped into an injection well located within the in situ oil barrier, and then groundwater samples were withdrawn for the next 30 h. After correction for dilution (using Br-as a conservative tracer of the injectate), perchlorate concentrations decreased by 78 % and nitrate concentrations decreased by 87 %, during the initial 8.6 h after the injection. The observed ratio of fractionation effects of O and Cl isotopes in perchlorate (ε18O/ε37Cl) was 2.6, which is similar to that observed in the laboratory using pure cultures (2.5). Denitrification by indigenous bacteria fractionated O and N isotopes in nitrate at a ratio of approximately 0.8 (ε18O/ε15N), which is within the range of values reported previously for denitrification. However, the magnitudes of the individual apparent in situ isotope fractionation effects for perchlorate and nitrate were appreciably smaller than those reported in homogeneous closed systems (0.2 to 0.6 times), even after adjustment for dilution. These results indicate that (1) isotope fractionation factor ratios (ε18O/ε37Cl, ε18O/ε15N) derived from homogeneous laboratory systems (e.g., pure culture studies) can be used qualitatively to confirm the occurrence of in situ biodegradation of both perchlorate and nitrate, but (2) the magnitudes of the individual apparent  values cannot be used quantitatively to estimate the in situ extent of biodegradation of either anion.

  17. Fractionation of stable isotopes in perchlorate and nitrate during in situ biodegradation in a sandy aquifer

    USGS Publications Warehouse

    Bohlke, Johnkarl F.; Hatzinger, P.B.; Sturchio, N.C.; Gu, B.; Heraty, L.J.; Borden, R.C.

    2009-01-01

    An in situ experiment was performed in a shallow alluvial aquifer in Maryland to quantify the fractionation of stable isotopes in perchlorate (Cl and O) and nitrate (N and O) during biodegradation. An emulsified soybean oil substrate that was previously injected into this aquifer provided the electron donor necessary for biological perchlorate reduction and denitrification. During the field experiment, groundwater extracted from an upgradient well was pumped into an injection well located within the in situ oil barrier, and then groundwater samples were withdrawn for the next 30 h. After correction for dilution (using Br– as a conservative tracer of the injectate), perchlorate concentrations decreased by 78% and nitrate concentrations decreased by 82% during the initial 8.6 h after the injection. The observed ratio of fractionation effects of O and Cl isotopes in perchlorate (e18O/e37Cl) was 2.6, which is similar to that observed in the laboratory using pure cultures (2.5). Denitrification by indigenous bacteria fractionated O and N isotopes in nitrate at a ratio of ~0.8 (e18O/e15N), which is within the range of values reported previously for denitrification. However, the magnitudes of the individual apparent in situ isotope fractionation effects for perchlorate and nitrate were appreciably smaller than those reported in homogeneous closed systems (0.2 to 0.6 times), even after adjustment for dilution. These results indicate that (1) isotope fractionation factor ratios (e18O/e37Cl, e18O/e15N) derived from homogeneous laboratory systems (e.g. pure culture studies) can be used qualitatively to confirm the occurrence of in situ biodegradation of both perchlorate and nitrate, but (2) the magnitudes of the individual apparent e values cannot be used quantitatively to estimate the in situ extent of biodegradation of either anion.

  18. Controls on the stable isotope compositions of travertine from hyperalkaline springs in Oman: Insights from clumped isotope measurements

    NASA Astrophysics Data System (ADS)

    Falk, E. S.; Guo, W.; Paukert, A. N.; Matter, J. M.; Mervine, E. M.; Kelemen, P. B.

    2016-11-01

    Carbonate formation at hyperalkaline springs is typical of serpentinization in peridotite massifs worldwide. These travertines have long been known to exhibit large variations in their carbon and oxygen isotope compositions, extending from apparent equilibrium values to highly depleted values. However, the exact causes of these variations are not well constrained. We analyzed a suite of well-characterized fresh carbonate precipitates and travertines associated with hyperalkaline springs in the peridotite section of the Samail ophiolite, Sultanate of Oman, and found their clumped isotope compositions vary systematically with formation environments. Based on these findings, we identified four main processes controlling the stable isotope compositions of these carbonates. These include hydroxylation of CO2, partial isotope equilibration of dissolved inorganic carbon, mixing between isotopically distinct carbonate end-members, and post-depositional recrystallization. Most notably, in fresh crystalline films on the surface of hyperalkaline springs and in some fresh carbonate precipitates from the bottom of hyperalkaline pools, we observed large enrichments in Δ47 (up to ∼0.2‰ above expected equilibrium values) which accompany depletions in δ18O and δ13C, yielding about 0.01‰ increase in Δ47 and 1.1‰ decrease in δ13C for every 1‰ decrease in δ18O, relative to expected equilibrium values. This disequilibrium trend, also reflected in preserved travertines ranging in age from modern to ∼40,000 years old, is interpreted to arise mainly from the isotope effects associated with the hydroxylation of CO2 in high-pH fluids and agrees with our first-order theoretical estimation. In addition, in some fresh carbonate precipitates from the bottom of hyperalkaline pools and in subsamples of one preserved travertine terrace, we observed additional enrichments in Δ47 at intermediate δ13C and δ18O, consistent with mixing between isotopically distinct carbonate end

  19. Influence of environmental factors on dissolved nitrate stable isotopes under denitrifying conditions - carbon sources and water isotopes

    NASA Astrophysics Data System (ADS)

    Wunderlich, A.; Meckenstock, R.; Einsiedl, F.

    2012-04-01

    Stable isotopes in dissolved nitrate are regularly used to identify sources of nitrate contamination in aquifers and water bodies. A dual isotope plot of 15N and 18O in nitrate can provide good evidence of the origin of such pollution as various sources have different isotopic signatures. Microbial denitrification changes both isotopic values by removing nitrate with lighter isotopes first, thereby increasing δ18O as well as δ15N. This change can distort the determination of sources but also has the potential to be used to identify and quantify microbial denitrification. Previous studies found a wide range of enrichment factors (ɛ) that did not allow conclusions towards the extent of microbial denitrification. However, it was found that during denitrification at each respective field site or laboratory experiment, there was a constant ratio in increase of the values of δ18O in relation to δ15N. That ratio was, however, not constant across field sites and the values published range from below 0.5 to more than 1.0. The reasons for these variations in enrichment factors and relative enrichment of oxygen compared to nitrogen are yet unknown. We conducted microcosm experiments with three different bacterial species to elucidate possible influences of environmental factors on these parameters. As a result we conclude that the type of carbon source available to denitrifying bacteria can play a role in the value of the enrichment factors, but not in the relative enrichment of the two isotopes. Specifically we found that complex hydrocarbons (toluene, benzoate) produce significantly different enrichment factors in nitrate than a simple hydrocarbon substrate (acetate). The relative enrichment of δ18O compared to δ15N was 0.86. We hypothesise that this influence is based on a variation in process kinetics of cross-membrane nitrate transport in relation to intracellular nitrate reduction. The core of the hypothesis is that nitrate transport into the cell becomes rate

  20. Late Paleocene Arctic Ocean shallow-marine temperatures from mollusc stable isotopes

    USGS Publications Warehouse

    Bice, Karen L.; Arthur, Michael A.; Marincovich, Louie, Jr.

    1996-01-01

    Late Paleocene high-latitude (80°N) Arctic Ocean shallow-marine temperatures are estimated from molluscan δ18O time series. Sampling of individual growth increments of two specimens of the bivalve Camptochlamys alaskensis provides a high-resolution record of shell stable isotope composition. The heavy carbon isotopic values of the specimens support a late Paleocene age for the youngest marine beds of the Prince Creek Formation exposed near Ocean Point, Alaska. The oxygen isotopic composition of regional freshwater runoff is estimated from the mean δ18O value of two freshwater bivalves collected from approximately coeval fluviatile beds. Over a 30 – 34‰ range of salinity, values assumed to represent the tolerance of C. alaskensis, the mean annual shallow-marine temperature recorded by these individuals is between 11° and 22°C. These values could represent maximum estimates of the mean annual temperature because of a possible warm-month bias imposed on the average δ18O value by slowing or cessation of growth in winter months. The amplitude of the molluscan δ18O time series probably records most of the seasonality in shallow-marine temperature. The annual temperature range indicated is approximately 6°C, suggesting very moderate high-latitude marine temperature seasonality during the late Paleocene. On the basis of analogy with modern Chlamys species, C. alaskensis probably inhabited water depths of 30–50 m. The seasonal temperature range derived from δ18O is therefore likely to be damped relative to the full range of annual sea surface temperatures. High-resolution sampling of molluscan shell material across inferred growth bands represents an important proxy record of seasonality of marine and freshwater conditions applicable at any latitude. If applied to other regions and time periods, the approach used here would contribute substantially to the paleoclimate record of seasonality.

  1. Stable isotope composition of cocoa beans of different geographical origin.

    PubMed

    Perini, Matteo; Bontempo, Luana; Ziller, Luca; Barbero, Alice; Caligiani, Augusta; Camin, Federica

    2016-09-01

    The isotopic profile (δ(13) C, δ(15) N, δ(18) O, δ(2) H, δ(34) S) was used to characterise a wide selection of cocoa beans from different renowned production areas (Africa, Asia, Central and South America). The factors most influencing the isotopic signatures of cocoa beans were climate and altitude for δ(13) C and the isotopic composition of precipitation water for δ(18) O and δ(2) H, whereas δ(15) N and δ(34) S were primarily affected by geology and fertilisation practises. Multi-isotopic analysis was shown to be sufficiently effective in determining the geographical origin of cocoa beans, and combining it with Canonical Discriminant Analysis led to more than 80% of samples being correctly reclassified. Copyright © 2016 John Wiley & Sons, Ltd.

  2. Stable isotope composition of cocoa beans of different geographical origin.

    PubMed

    Perini, Matteo; Bontempo, Luana; Ziller, Luca; Barbero, Alice; Caligiani, Augusta; Camin, Federica

    2016-09-01

    The isotopic profile (δ(13) C, δ(15) N, δ(18) O, δ(2) H, δ(34) S) was used to characterise a wide selection of cocoa beans from different renowned production areas (Africa, Asia, Central and South America). The factors most influencing the isotopic signatures of cocoa beans were climate and altitude for δ(13) C and the isotopic composition of precipitation water for δ(18) O and δ(2) H, whereas δ(15) N and δ(34) S were primarily affected by geology and fertilisation practises. Multi-isotopic analysis was shown to be sufficiently effective in determining the geographical origin of cocoa beans, and combining it with Canonical Discriminant Analysis led to more than 80% of samples being correctly reclassified. Copyright © 2016 John Wiley & Sons, Ltd. PMID:27484307

  3. Use of Isotope Ratio Mass Spectrometry (IRMS) Determination ((18)O/(16)O) to Assess the Local Origin of Fish and Asparagus in Western Switzerland.

    PubMed

    Rossier, Joël S; Maury, Valérie; de Voogd, Blaise; Pfammatter, Elmar

    2014-10-01

    Here we present the use of isotope ratio mass spectrometry (IRMS) for the detection of mislabelling of food produced in Switzerland. The system is based on the analysis of the oxygen isotope distribution in water (δ(18)O). Depending on the location on the earth, lake or groundwater has a specific isotopic distribution, which can serve as a fingerprint in order to verify whether a product has grown by means of the corresponding water. This report presents specifically the IRMS technique and the results obtained in the origin detection of fish grown in selected Swiss lakes as well as asparagus grown in Valais ground. Strengths and limitations of the method are presented for both cited products; on one hand, the technique is relatively universal for any product which contains significant water but on the other hand, it necessitates a rather heavy workload to build up a database of water δ(18)O values of products of different origins. This analytical tool is part of the concept of combating fraud currently in use in Switzerland. PMID:25437160

  4. Stable isotopes of authigenic minerals in variably-saturated fractured tuff

    SciTech Connect

    Weber, D.S.; Evans, D.D.

    1988-11-01

    Identifying stable isotope variation and mineralogical changes in fractured rock may help establish the history of climatic and geomorphological processes that might affect the isolation properties of a waste repository site. This study examines the use of the stable isotope ratios of oxygen ({sup 18}O/{sup 16}O) and carbon ({sup 13}C/{sup 12}C) in authigenic minerals as hydrogeochemical tools tracing low-temperature rock-water interaction in variably-saturated fractured stuff. Isotopic compositions of fracture-filling and rock matrix minerals in the Apache Leap tuff, near Superior, Arizona were concordant with geothermal temperatures and in equilibrium with water isotopically similar to present-day meteoric water and groundwater. Oxygen and carbon isotope ratios of fracture-filling, in unsaturated fractured tuff, displayed an isotopic gradient believed to result from near-surface isotopic enrichment due to evaporation rather than the effects of rock-water interaction. Oxygen isotope ratios of rock matrix opal samples exhibited an isotopic gradient believed to result from, leaching and reprecipitation of silica at depth. Methods and results can be used to further define primary flowpaths and the movement of water in variably-saturated fractured rock. 71 refs., 23 figs., 3 tabs.

  5. Stable Isotope Fluxes of CO2 and H2O for a Temperate Deciduous Forest in Canada

    NASA Astrophysics Data System (ADS)

    Santos, E. A.; Wagner-Riddle, C.; Warland, J. S.; Brown, S. E.; Lee, X.; Kim, K.; Staebler, R. M.

    2009-12-01

    Stable isotopes of carbon dioxide and water vapor, including 13CO2, C18O16O, HDO and H218O have been used to study the carbon and water cycle. These stable isotopes are particularly useful to separate the contribution of different ecosystem components to the net flux. For example, 13CO2 can be applied as a tracer at sites where soil organic matter and plants present a different isotopic ratio. C18O16O can be used to partitioning soil from foliar respiration, since leaf water is significantly enriched in 18O during the day as a result of leaf transpiration. Continuous measurements of CO2 and H2O exchange and their isotopic values in ecosystems are necessary to better understand the processes related to isotope discrimination. The objective of this study was to investigate the isotopic fluxes of CO2 and H2O continuously in a temperate deciduous forest. The experiment was conducted at the Environment Canada research station, Camp Borden, ON, Canada from June to August 2009. Mixing ratios of C16O2, 13CO2, C18O16O, H216O, HDO and H218O in the sampled air were measured continuously using two tunable diode laser trace gas analyzers (TGA 100A, Campbell Sci., UT, USA). Air was sampled at two heights above the canopy and two heights in the under-storey. The TGA mixing ratio measurements were calibrated by regularly measuring tanks with known concentrations of CO2 isotopic species and water vapor of known isotopic ratios. Atmospheric carbon dioxide (δ13C, and δ18O) and water vapor isotope ratios were calculated, and the isotope signatures of CO2 (δ13N and δ18N) and water vapor flux were obtained based on the flux ratio method. Atmospheric δ13C ranged from -7 (during daytime) to -10 per mil during nighttime, while δ18O values ranged from -1 to -3 per mil. The isotope ratio of the CO2 fluxes in the overstorey ranged from -15 to -22 per mil for δ18N and -22 to -32 per mil for δ13N. These preliminary data will be discussed in light of H2O vapor and flux isotopic ratio

  6. Stable isotope ratios in meteoric recharge and groundwater at Mt. Vulture volcano, southern Italy

    NASA Astrophysics Data System (ADS)

    Paternoster, M.; Liotta, M.; Favara, R.

    2008-01-01

    SummaryA rain gauge network consisting of five sites located at different altitudes, ranging from 320 to 1285 m.a.s.l., was installed at Mt. Vulture volcano (southern Italy). Rain water samples were collected monthly over a two-year period and their isotopic composition (δ 18O and δD) was analyzed. During the same period, circulating groundwater was sampled from 24 springs and wells distributed throughout the study area. Monthly isotopic composition values were used to determine the local meteoric water line (LMWL). Its slope is slightly lower than the relationship defined by Longinelli and Selmo (Longinelli, A., Selmo, E., 2003. Isotopic composition of precipitation in Italy: a first overall map. J. Hydrol. 270, 75-88) for southern Italy. The groundwater samples analyzed were distributed essentially along the LMWL. The weighted local meteoric water line (WLMWL), defined through the mean values weighted by the rainfall amount, however, may define in a short range the meteoric end-member in the local hydrological cycle more precisely. Since most of the groundwater sampling locations do not show seasonal variations in their stable isotope values, the flow system appears to be relatively homogeneous. The mean altitude of the recharge by rainfall infiltration was estimated on the basis of the local vertical isotopic gradient δ 18O. A few springs, which show anomalous isotopic values, reveal more regional circulation systems, associated with tectonic structures responsible for the ascent of deeper water.

  7. Stable isotopic analyses in paleoclimatic reconstruction

    SciTech Connect

    Wigand, P.E.

    1995-09-01

    Most traditional paleoclimatic proxy data have inherent time lags between climatic input and system response that constrain their use in accurate reconstruction of paleoclimate chronology, scaling of its variability, and the elucidation of the processes that determine its impact on the biotic and abiotic environment. With the exception of dendroclimatology, and studies of short-lived organisms and pollen recovered from annually varved lacustrine sediments, significant periods of time ranging from years, to centuries, to millennia may intervene between climate change and its first manifestation in paleoclimatic proxy data records. Reconstruction of past climate through changes in plant community composition derived from pollen sequences and plant remains from ancient woodrat middens, wet environments and dry caves all suffer from these lags. However, stable isotopic analyses can provide more immediate indication of biotic response to climate change. Evidence of past physiological response of organisms to changes in effective precipitation as climate varies can be provided by analyses of the stable isotopic content of plant macrofossils from various contexts. These analyses consider variation in the stable isotopic (hydrogen, oxygen and carbon) content of plant tissues as it reflects (1) past global or local temperature through changes in meteoric (rainfall) water chemistry in the case of the first two isotopes, and (2) plant stress through changes in plant respiration/transpiration processes under differing water availability, and varying atmospheric CO, composition (which itself may actually be a net result of biotic response to climate change). Studies currently being conducted in the Intermountain West indicate both long- and short-term responses that when calibrated with modem analogue studies have the potential of revealing not only the timing of climate events, but their direction, magnitude and rapidity.

  8. Quantifying uncertainty in stable isotope mixing models

    SciTech Connect

    Davis, Paul; Syme, James; Heikoop, Jeffrey; Fessenden-Rahn, Julianna; Perkins, George; Newman, Brent; Chrystal, Abbey E.; Hagerty, Shannon B.

    2015-05-19

    Mixing models are powerful tools for identifying biogeochemical sources and determining mixing fractions in a sample. However, identification of actual source contributors is often not simple, and source compositions typically vary or even overlap, significantly increasing model uncertainty in calculated mixing fractions. This study compares three probabilistic methods, SIAR [Parnell et al., 2010] a pure Monte Carlo technique (PMC), and Stable Isotope Reference Source (SIRS) mixing model, a new technique that estimates mixing in systems with more than three sources and/or uncertain source compositions. In this paper, we use nitrate stable isotope examples (δ15N and δ18O) but all methods tested are applicable to other tracers. In Phase I of a three-phase blind test, we compared methods for a set of six-source nitrate problems. PMC was unable to find solutions for two of the target water samples. The Bayesian method, SIAR, experienced anchoring problems, and SIRS calculated mixing fractions that most closely approximated the known mixing fractions. For that reason, SIRS was the only approach used in the next phase of testing. In Phase II, the problem was broadened where any subset of the six sources could be a possible solution to the mixing problem. Results showed a high rate of Type I errors where solutions included sources that were not contributing to the sample. In Phase III some sources were eliminated based on assumed site knowledge and assumed nitrate concentrations, substantially reduced mixing fraction uncertainties and lowered the Type I error rate. These results demonstrate that valuable insights into stable isotope mixing problems result from probabilistic mixing model approaches like SIRS. The results also emphasize the importance of identifying a minimal set of potential sources and quantifying uncertainties in source isotopic composition as well as demonstrating the value of additional information in reducing the

  9. Climatic significance of stable isotopes in precipitation from western Romania

    NASA Astrophysics Data System (ADS)

    Ersek, Vasile; Onac, Bogdan

    2016-04-01

    The oxygen and deuterium (δ18O and δD) isotopic composition of meteoric precipitation has been used as proxy to advance our understanding of past and present atmospheric circulation. Precipitation δ18O is a primary control on cave speleothem δ18O which is one of the main methods used to reconstruct past climatic variability on a variety of timescales. Here we present δ18O and δD in precipitation and cave drip waters from Urşilor Cave located in the Apuseni Mountains, western Romania in order to better understand the relationship between climate and speleothem δ18O at this site. Samples of weekly precipitation and cave drip water (4-day intervals) were collected between July 2010 and June 2011. In order to draw robust palaeoclimatic information from speleothems at Ursilor Cave we aim to establish the climatic controls on δ18O composition of precipitation in western Romania and determine the source of air masses delivering moisture at our site. Furthermore, we evaluate the extent to which any climatic signature is preserved in the drip waters from which the speleothem calcite precipitates.

  10. Correlation between multielement stable isotope ratio and geographical origin in Peretta cows' milk cheese.

    PubMed

    Manca, G; Franco, M A; Versini, G; Camin, F; Rossmann, A; Tola, A

    2006-03-01

    The aim of this study was to characterize the isotopic composition and protect "Peretta" cows' milk cheese, a typical product of Sardinia, against other cheeses of the same appearance sold under the same name, but made of raw materials from northern Europe. The study was concerned with 3 types of cheese: those produced in local dairies from milk from free-grazing or pasture-grazing cows in Sardinia (local dairy product), cheeses made on an industrial scale from milk produced by intensive farming in Sardinia (factory cheese), and cheeses made with raw materials imported from other countries (imported product). To distinguish the Sardinian cheeses from the imported product, the stable isotope ratios 13C/12C, 15N/14N, D/H, 34S/32S, and (18)O/(16)O were used. Determination of the isotopic data delta13C, delta15N, delta2H, and delta34S was performed in the casein fraction, whereas delta(18)O and delta13C were determined in the glycerol fraction. Measurements were performed by isotope ratio mass spectrometry. A comparison between mean values of the isotope ratios by statistical analysis (ANOVA and Tukey's test) showed that the greatest difference between the 3 types of cheese (local dairy, factory, and imported products) was in the 13C/12C, 34S/32S, and (18)O/(16)O isotope ratios. In the other parameters, either no differences (delta15N) or minimal differences (delta2H) were found. Evaluation of the data by multivariate statistical analysis (principal component analysis and hierarchical cluster analysis) revealed that the isotope characteristics of the factory products were similar to those of the cheeses produced from imported raw materials, whereas a difference was found between the local dairy-produced cheeses and the products in the other 2 categories. PMID:16507675

  11. Direct stable isotope porewater equilibration and identification of groundwater processes in heterogeneous sedimentary rock.

    PubMed

    David, Katarina; Timms, Wendy; Baker, Andy

    2015-12-15

    The off-axis integrated cavity output spectrometry (ICOS) method to analyse porewater isotopic composition has been successfully applied over the last decade in groundwater studies. This paper applies the off-axis ICOS method to analyse the porewater isotopic composition, attempts to use the isotopic shift in groundwater values along with simple geochemical mixing model to define the groundwater processes in the Sydney Basin, Australia. Complementary data included geophysical, hydrogeological, geochemical, and mineralogical investigations. Porewater from core samples were analysed for δ(18)O and δ(2)H from various sedimentary units in the Basin and compared to endpoint water members. Stable δ(18)O and δ(2)H values of porewaters in the Basin (-9.5 to 2.8‰ for δ(18)O and -41.9 to 7.9‰ for δ(2)H) covered a relatively narrow range in values. The variability in water isotopes reflects the variability of the input signal, which is the synoptic variability in isotopic composition of rainfall, and to a minor extent the subsequent evaporation. The porosity, bulk density and mineralogy data demonstrate the heterogeneity that adds the complexity to variations in the isotope profile with depth. The source of chloride in the sedimentary sequence was related to rock-water and cement/matrix-water interaction rather than to evaporation. The heterogeneous character of the sedimentary rock strata was supported by a change in pore pressures between units, density and variability in rock geochemical analyses obtained by using X-ray fluorescence (XRF) and X-ray power diffraction analyses. This research identified distinct hydrogeological zones in the Basin that were not previously defined by classic hydrogeological investigations. Isotopic signature of porewaters along the detailed vertical profile in combination with mineralogical, geochemical, geophysical and hydrogeological methods can provide useful information on groundwater movement in deep sedimentary environments. The

  12. Correlation between multielement stable isotope ratio and geographical origin in Peretta cows' milk cheese.

    PubMed

    Manca, G; Franco, M A; Versini, G; Camin, F; Rossmann, A; Tola, A

    2006-03-01

    The aim of this study was to characterize the isotopic composition and protect "Peretta" cows' milk cheese, a typical product of Sardinia, against other cheeses of the same appearance sold under the same name, but made of raw materials from northern Europe. The study was concerned with 3 types of cheese: those produced in local dairies from milk from free-grazing or pasture-grazing cows in Sardinia (local dairy product), cheeses made on an industrial scale from milk produced by intensive farming in Sardinia (factory cheese), and cheeses made with raw materials imported from other countries (imported product). To distinguish the Sardinian cheeses from the imported product, the stable isotope ratios 13C/12C, 15N/14N, D/H, 34S/32S, and (18)O/(16)O were used. Determination of the isotopic data delta13C, delta15N, delta2H, and delta34S was performed in the casein fraction, whereas delta(18)O and delta13C were determined in the glycerol fraction. Measurements were performed by isotope ratio mass spectrometry. A comparison between mean values of the isotope ratios by statistical analysis (ANOVA and Tukey's test) showed that the greatest difference between the 3 types of cheese (local dairy, factory, and imported products) was in the 13C/12C, 34S/32S, and (18)O/(16)O isotope ratios. In the other parameters, either no differences (delta15N) or minimal differences (delta2H) were found. Evaluation of the data by multivariate statistical analysis (principal component analysis and hierarchical cluster analysis) revealed that the isotope characteristics of the factory products were similar to those of the cheeses produced from imported raw materials, whereas a difference was found between the local dairy-produced cheeses and the products in the other 2 categories.

  13. Validating the regional hydrogeological models with stable isotope data in precipitation

    NASA Astrophysics Data System (ADS)

    Kalvāns, Andis; Babre, Alise; Popovs, Konārds; Timuhins, Andrejs; Spalviņš, Aivars

    2016-04-01

    Stable isotopes 18O and 2H are a conservative tracer in the subsurface flow. The precipitation is the primary input in the groundwater systems, hens' there should be a positive regional correlation of the stable isotope values in the groundwater and precipitation. The local recharge peculiarities should modulate the precipitation isotope signal and introduce some noise but not eliminate the correlation completely. Modelled isotope values in the precipitation (Terzer et al. 2013) were compared to the actually observed values in the groundwater (Babre et al, in print) in the Baltic Artesian Basin, located at the South-East cost of the Baltic Sea. But positive and significant correlation was not found. Two regional hydrogeological models LAMO (Spalvins et al. 2015) and MOSYS (Virbulis et al. 2013) were used to trace the likely recharge area of the considered groundwater samples. A simple particle tracing of the LAMO produced a statistically significant, positive correlation between observed δ18O values in the relatively young groundwater (modelled residence time <7500 years) and precipitation at the location of the recharge. More complicated modelling system MOSYS with coarser resolution allowed to simulate the large scale downward depletion of the δ18O values in the groundwater. It is concluded that observed stable isotope values in the groundwater can be compared to the precipitation values in the recharge areas to validate the modelled regional flow patterns. This research is supported by Latvian National Research Programme EVIDENnT project "Groundwater and climate scenarios". References Babre, A., Kalv¯a ns, K., Popovs, K., Retiķe, I., D¯e liņa, A., Vaikmäe, R., Martma, T. (in print) New isotope data in groundwater from Latvia, central part of the Baltic Basin. Isotopes in Environmental & Health Studies Spalvins, A., Slangens j., L¯a ce I., Aleks¯a ns, O., Krauklis, K., 2015. Improvement of Hydrogeological Models: A Case Study. In International Review on

  14. Stable oxygen and hydrogen isotope analyses of bowhead whale baleen as biochemical recorders of migration and arctic environmental change

    NASA Astrophysics Data System (ADS)

    deHart, Pieter A. P.; Picco, Candace M.

    2015-06-01

    An analysis of the stable isotopes of oxygen (δ18O) and hydrogen (δD) was used to examine the linkage between sea ice concentration and the migration of western arctic bowhead whales (Balaena mysticetus; WABW). We compared δ18O and δD variability along the length of WABW baleen with isotopic values of zooplankton prey from different WABW habitat, with published δ13C and δ15N data, and with historical sea ice records. Zooplankton signatures varied widely (δ18O = -13‰-56‰; δD = -220‰ to -75‰), with regional separation between winter (Bering Sea) and summer (eastern Beaufort Sea) habitats of WABW observable in δD. The δ18O and δD of WABW varied significantly along the length of baleen (δ18O = 8-18‰; δD = -180 to -80‰), confirming seasonal migration and reflecting distinct regional dietary variation in isotopes. WABW migration appears to have varied concomitant with temporal sea ice concentration (SIC) changes; in years with high SIC, the difference in δD of WABW baleen between seasonal habitats was significantly greater than low SIC periods. This work shows that SIC is not only a determinant of habitat accessibility for WABW, but baleen may also be a record of historical SIC and Arctic climate.

  15. Eastern Equatorial Pacific paleoceanography during the last 8 Myr: Untangling proxy signals from bulk sediment stable carbon and oxygen isotopes.

    NASA Astrophysics Data System (ADS)

    Reghellin, Daniele; Coxall, Helen K.; Backman, Jan; Dickens, Gerald R.

    2014-05-01

    The stable carbon and oxygen isotope signatures (δ13C and δ18O) of bulk sediment calcium carbonate (CaCO3) are routinely analyzed in paleoceanographic studies. However little is known about the relative contribution of different biogenic CaCO3 components to these mixed 'bulk' isotopic signals and how this might correlate spatial or temporal differences in paleoceanography and carbonate preservation, especially in deep water settings close to the lysocline where paleoceanographic data is at a premium. Here we attempt to improve the understanding of bulk sediment δ13C and δ18O as a paleoceanographic tool by untangling the isotopic contribution of different biogenic components, principally foraminifera and calcareous nannofossils, in a series of deep sea sediment cores from the deep equatorial Pacific spanning the last 8 Myr. This region is characterized by extremely dynamic oceanography but the history is difficult to resolve due to the paucity of available proxy records. Here existing bulk sediment δ13C and δ18O from ODP Leg 138 are combined with 791 new bulk sediment δ13C and δ18O data from IODP Site U1338 and DSDP Site 573, situated within the belt of strong equatorial upwelling and high primary productivity in the eastern equatorial Pacific (EEP). For a subset of 100 of the new samples, the δ13C and δ18O was measured on isolated

  16. Unveiling stomata 24/7: can we use carbonyl sulfide (COS) and oxygen isotopes (18O) to constrain estimates of nocturnal transpiration across different evolutionary plant forms?

    NASA Astrophysics Data System (ADS)

    Gimeno, Teresa E.; Ogee, Jerome; Bosc, Alexander; Genty, Bernard; Wohl, Steven; Wingate, Lisa

    2015-04-01

    Numerous studies have reported a continued flux of water through plants at night, suggesting that stomata are not fully closed. Growing evidence indicates that this nocturnal flux of transpiration might constitute an important fraction of total ecosystem water use in certain environments. However, because evaporative demand is usually low at night, nocturnal transpiration fluxes are generally an order of magnitude lower than rates measured during the day and perilously close to the measurement error of traditional gas-exchange porometers. Thus estimating rates of stomatal conductance in the dark (gnight) precisely poses a significant methodological challenge. As a result, we lack accurate field estimates of gnight and how it responds to different atmospheric drivers, indicating the need for a different measurement approach. In this presentation we propose a novel method to obtain detectable and robust estimates of gnight. We will demonstrate using mechanistic theory how independent tracers including the oxygen isotope composition of CO2 (δ18O) and carbonyl sulfide (COS) can be combined to obtain robust estimates of gnight. This is because COS and CO18O exchange within leaves are controlled by the light insensitive enzyme carbonic anhydrase. Thus, if plant stomata are open in the dark we will continue to observe COS and CO18O exchange. Using our theoretical model we will demonstrate that the exchange of these tracers can now be measured using advances in laser spectrometry techniques at a precision high enough to determine robust estimates of gnight. We will also present our novel experimental approach designed to measure simultaneously the exchange of CO18O and COS alongside the conventional technique that relies on measuring the total water flux from leaves in the dark. Using our theoretical approach we will additionally explore the feasibility of our proposed experimental design to detect variations in gnight during drought stress and across a variety of plant

  17. [Review of dual stable isotope technique for nitrate source identification in surface- and groundwater in China].

    PubMed

    Xu, Zhi-Wei; Zhang, Xin-Yu; Yu, Gui-Rui; Sun, Xiao-Min; Wen, Xue-Fa

    2014-08-01

    Water nitrate (NO3-) contamination is a world-wide environmental problem under the effects of intensive human activities. Sources identification of NO3- contamination in water is important for better management of water quality. Dual stable isotope data of nitrate nitrogen (delta15N) and nitrate oxygen (delta18O) combined with other stable isotopes and chemical analysis data have been frequently used to identify NO3- sources, differentiate percentage of the different NO3- sources and assess the nitrification/denitrification processes of surface water, groundwater and precipitation, respectively. This review summarized the analysis technique of nitrate delta15N and delta18O in domestic and abroad, assessed typical values of delta15N, delta18O from different NO3- sources and evaluated the progress in application of dual stable isotope of delta15N and delta18O technique to trace NO3- sources in surface- and ground-water. Both ion exchange-AgNO3 and bacteria denitrifying methods have been successfully used in tracing water nitrate sources nationwide. The comprehensive metadata analysis of nitrate sources showed that the delta15N values of sewage and manure, soil, precipitation, fertilizer ranged from 3 per thousand to 17 per thousand, 3 per thousand to 8 per thousand, - 9 per thousand to 9 per thousand, -2 per thousand to 4 per thousand, respectively. And the delta15N values of ammonium fertilizer ranged from - 4 per thousand to 2 per thousand. According to the stable isotope technique, sewage and manure were identified as the major nitrate sources of surface- and ground-water in China. This indicated that municipal sewage and aquaculture exerted serious influence on the nitrate pollution of surface water. In the future, long-term monitoring, dual stable isotope fingerprinting and hydro-chemical analysis should be applied together to quantitatively differentiate contribution of nitrate sources, and to assess seasonal dynamic of nitrate sources. It will provide useful

  18. Recent planktic foraminifers in the Fram Strait (Arctic Ocean): carbon and oxygen stable isotope composition

    NASA Astrophysics Data System (ADS)

    Pados, T.; Spielhagen, R. F.; Bauch, D.; Meyer, H.; Segl, M.

    2012-12-01

    In paleoceanographic reconstructions the carbon isotopic compositions (δ13C) of fossil foraminifers refer to, e.g., paleoproductivity and stratification, while oxygen isotopic18O) records provide information about variations in sea surface temperatures and salinities in the past. However, for a correct interpretation of the fossil data it is important to improve our understanding of the correlation between recent oceanic variability and the composition of shells of living calcareous microorganisms. For this, the upper water column and sediment surface in the Fram Strait (Arctic Ocean, 78°50'N, 5°W-8°E) were sampled for planktic foraminifer species Neogloboquadrina pachyderma (sin.) and Turborotalita quinqueloba with a large-diameter multinet and a multicorer, respectively. The δ13C and δ18O values of the shells are compared to the stable isotope composition of the ambient water and to equilibrium calcite values to define the preferred calcification depths of the foraminifers and to determine the factors controlling the isotopic signature of these calcareous microorganisms. The study area was chosen because of its high oceanographic variability: in the eastern Fram Strait the northward flowing West Spitsbergen Current (WSC) carries Atlantic Water, with a thin mixed layer on top, while in the west the upper 200 m consists of cold, low-saline Arctic outflow waters of the East Greenland Current (EGC) and warmer, saline waters of Atlantic origin underneath. Despite this variable oceanographic regime along the studied transect, the stable carbon isotope ratios of the shells do not show major differences according to their horizontal but to their vertical distribution: the δ13C values of N. pachyderma (sin.) from plankton tow samples vary roughly between -1 and -0.1‰ depending on the water depth, while the δ18O values of the tests differ more between the stations.

  19. Understanding key drivers controlling daily stable isotope variations in precipitation of Costa Rica, Central America

    NASA Astrophysics Data System (ADS)

    Sanchez-Murillo, Ricardo; Welsh, Kristin; Birkel, Christian; Esquivel-Hernández, Germain; Corrales-Salazar, Jose; Boll, Jan; Brooks, Erin; Roupsard, Olivier; Katchan, Irina; Arce-Mesén, Rafael; Soulsby, Chris; Araguás-Araguás, Luis

    2015-04-01

    Costa Rica is located on the Central American Isthmus, which receives direct moisture inputs from the Caribbean Sea and the Pacific Ocean. The relatively narrow, but high relief Central American land bridge is characterized by unique mountainous and lowland microclimates. However, only limited knowledge exists about the impact of relief and regional atmospheric circulation patterns on precipitation origin, transport, and isotopic composition in this tropical region. Therefore, the main scope of this study is to identify the key drivers controlling variations in meteoric waters of Costa Rica using stable isotopes based on daily sample collection for the year 2013. The monitoring sites comprise three strategic locations across Costa Rica: Heredia (Central Valley), Turrialba (Caribbean slope), and Caño Seco (South Pacific slope). Sporadic dry season rain is mostly related to isolated enriched events ranging from -5.8‰ d18O up to -0.9‰ d18O. By mid-May, the Intertropical Convergence Zone reaches Costa Rica resulting in a notable depletion in isotope ratios (up to -18.5‰ d18O). HYSPLIT back air mass trajectories indicate the strong influence on the origin and transport of precipitation of two main moisture transport mechanisms, the Caribbean Low Level Jet and the Colombian Low Level Jet as well as localized convection events. Multiple linear regression models constructed based on Random Forests of surface meteorological information and atmospheric sounding profiles suggest that Lifted Condensation Level and surface relative humidity are the main factors controlling isotopic variations. These findings diverge from the recognized 'amount effect' in monthly composite samples across the tropics. Understanding of stable isotope dynamics in tropical precipitation can be used to enhance catchment and groundwater modeling efforts in ungauged basins where scarcity of long-term monitoring data drastically limit current and future water resources management.

  20. Minimal influence of recrystallization on middle Miocene benthic foraminiferal stable isotope stratigraphy in the eastern equatorial Pacific

    NASA Astrophysics Data System (ADS)

    Voigt, Janett; Hathorne, Ed C.; Frank, Martin; Holbourn, Ann

    2016-01-01

    Stable carbon and oxygen isotopes (δ13C and δ18O) of foraminiferal tests are amongst the most important tools in paleoceanography, but the extent to which recrystallization can alter the isotopic composition of the tests is not well known. Here we compare three middle Miocene (16-13 Ma) benthic foraminiferal stable isotope records from eastern equatorial Pacific sites with different diagenetic histories to investigate the effect of recrystallization. To test an extreme case, we analyzed stable isotope compositions of benthic foraminifera from Integrated Ocean Drilling Program Site U1336, for which the geochemistry of bulk carbonates and associated pore waters indicates continued diagenetic alteration in sediments > 14.7 Ma. Despite this diagenetic overprinting, the amplitudes and absolute values of the analyzed U1336 stable isotopes agree well with high-resolution records from better preserved Sites U1337 and U1338 nearby. Our results suggest that although benthic foraminiferal tests of all three sites show some degree of textural changes due to recrystallization, they have retained their original stable isotope signatures. The good agreement of the benthic foraminiferal stable isotope records demonstrates that recrystallization occurred extremely rapidly (< 100 kyr) after deposition. This is confirmed by the preservation of orbital cyclicities in U1336 stable isotope data and δ18O values being different to inorganic calcite that would precipitate from U1336 pore waters during late recrystallization. The close similarity of the benthic foraminiferal stable isotope records between the sites allows the well-resolved paleomagnetic results of Site U1336 to be transferred to Sites U1337 and U1338 improving the global geological timescale.

  1. Comparing Stable Water Isotope Variation in Atmospheric Moisture Observed over Coastal Water and Forests

    NASA Astrophysics Data System (ADS)

    Lai, C. T.; Rambo, J. P.; Welp, L. R.; Bible, K.; Hollinger, D. Y.

    2014-12-01

    Stable oxygen (δ18O) and hydrogen (δD) isotopologues of atmospheric moisture are strongly influenced by large-scale synoptic weather cycles, surface evapotranspiration and boundary layer mixing. Atmospheric water isotope variation has been shown to empirically relate to relative humidity (Rh) of near surface moisture, and to a less degree, air temperature. Continuous δ18O and δD measurements are becoming more available, providing new opportunities to investigate processes that control isotope variability. This study shows the comparison of δ18O and δD measured at a continental location and over coastal waters for 3 seasons (spring to fall, 2014). The surface moisture isotope measurements were made using two LGR spectroscopy water vapor isotope analyzers (Los Gatos Research Inc.), one operated in an old-growth coniferous forest at Wind River field station, WA (45.8205°N, 121.9519°W), and another sampling marine air over seawater at the Scripps Pier in San Diego, CA (32.8654°N, 117.2536°W), USA. Isotope variations were measured at 1Hz and data were reported as hourly averages with an overall accuracy of ±0.1‰ for δ18O, ±0.5‰ for δ2H. Day-to-day variations in δ18O and δD are shown strongly influenced by synoptic weather events at both locations. Boundary layer mixing between surface moisture and the dry air entrained from the free troposphere exerts a midday maximum and a consistent diel pattern in deuterium excess (dx). At the forest site, surface moisture also interacts with leaf water through transpiration during the day and re-equilibration at night. The latter occurs by retro-diffusion of atmospheric H2O molecules into leaf intercellular space, which becomes intensified as Rh increaes after nightfall, and continues until sunrise, to counter-balance the evaporative isotopic enrichment in leaf water on a daily basis. These vegetation effects lead to negative dx values consistently observed at nighttime in this continental location that were not

  2. Oxygen isotope ratios (18O/16O) of hemicellulose-derived sugar biomarkers in plants, soils and sediments as paleoclimate proxy II: Insight from a climate transect study

    NASA Astrophysics Data System (ADS)

    Tuthorn, Mario; Zech, Michael; Ruppenthal, Marc; Oelmann, Yvonne; Kahmen, Ansgar; Valle, Héctor Francisco del; Wilcke, Wolfgang; Glaser, Bruno

    2014-02-01

    The oxygen isotopic composition of precipitation (δ18Oprec) is well known to be a valuable (paleo-)climate proxy. Paleosols and sediments and hemicelluloses therein have the potential to serve as archives recording the isotopic composition of paleoprecipitation. In a companion paper (Zech et al., 2014) we investigated δ18Ohemicellulose values of plants grown under different climatic conditions in a climate chamber experiment. Here we present results of compound-specific δ18O analyses of arabinose, fucose and xylose extracted from modern topsoils (n = 56) along a large humid-arid climate transect in Argentina in order to answer the question whether hemicellulose biomarkers in soils reflect δ18Oprec. The results from the field replications indicate that the homogeneity of topsoils with regard to δ18Ohemicellulose is very high for most of the 20 sampling sites. Standard deviations for the field replications are 1.5‰, 2.2‰ and 1.7‰, for arabinose, fucose and xylose, respectively. Furthermore, all three hemicellulose biomarkers reveal systematic and similar trends along the climate gradient. However, the δ18Ohemicellulose values (mean of the three sugars) do not correlate positively with δ18Oprec (r = -0.54, p < 0.014, n = 20). By using a Péclet-modified Craig-Gordon (PMCG) model it can be shown that the δ18Ohemicellulose values correlate highly significantly with modeled δ18Oleaf water values (r = 0.81, p < 0.001, n = 20). This finding suggests that hemicellulose biomarkers in (paleo-)soils do not simply reflect δ18Oprec but rather δ18Oprec altered by evaporative 18O enrichment of leaf water due to evapotranspiration. According to the modeling results, evaporative 18O enrichment of leaf water is relatively low (˜10‰) in the humid northern part of the Argentinian transect and much higher (up to 19‰) in the arid middle and southern part of the transect. Model sensitivity tests corroborate that changes in relative air humidity exert a dominant

  3. Oxygen isotope ratios (18O/16O) of hemicellulose-derived sugar biomarkers in plants, soils and sediments as paleoclimate proxy II: Insight from a climate transect study

    NASA Astrophysics Data System (ADS)

    Tuthorn, Mario; Zech, Michael; Ruppenthal, Marc; Oelmann, Yvonne; Kahmen, Ansgar; Valle, Héctor Francisco del; Wilcke, Wolfgang; Glaser, Bruno

    2014-02-01

    The oxygen isotopic composition of precipitation (δ18Oprec) is well known to be a valuable (paleo-)climate proxy. Paleosols and sediments and hemicelluloses therein have the potential to serve as archives recording the isotopic composition of paleoprecipitation. In a companion paper (Zech et al., 2014) we investigated δ18Ohemicellulose values of plants grown under different climatic conditions in a climate chamber experiment. Here we present results of compound-specific δ18O analyses of arabinose, fucose and xylose extracted from modern topsoils (n = 56) along a large humid-arid climate transect in Argentina in order to answer the question whether hemicellulose biomarkers in soils reflect δ18Oprec. The results from the field replications indicate that the homogeneity of topsoils with regard to δ18Ohemicellulose is very high for most of the 20 sampling sites. Standard deviations for the field replications are 1.5‰, 2.2‰ and 1.7‰, for arabinose, fucose and xylose, respectively. Furthermore, all three hemicellulose biomarkers reveal systematic and similar trends along the climate gradient. However, the δ18Ohemicellulose values (mean of the three sugars) do not correlate positively with δ18Oprec (r = -0.54, p < 0.014, n = 20). By using a Péclet-modified Craig-Gordon (PMCG) model it can be shown that the δ18Ohemicellulose values correlate highly significantly with modeled δ18Oleaf water values (r = 0.81, p < 0.001, n = 20). This finding suggests that hemicellulose biomarkers in (paleo-)soils do not simply reflect δ18Oprec but rather δ18Oprec altered by evaporative 18O enrichment of leaf water due to evapotranspiration. According to the modeling results, evaporative 18O enrichment of leaf water is relatively low (˜10‰) in the humid northern part of the Argentinian transect and much higher (up to 19‰) in the arid middle and southern part of the transect. Model sensitivity tests corroborate that changes in relative air humidity exert a dominant

  4. Stable isotope anatomy of tropical cyclone Ita, North-Eastern Australia, April 2014.

    PubMed

    Munksgaard, Niels C; Zwart, Costijn; Kurita, Naoyuki; Bass, Adrian; Nott, Jon; Bird, Michael I

    2015-01-01

    The isotope signatures registered in speleothems during tropical cyclones (TC) provides information about the frequency and intensity of past TCs but the precise relationship between isotopic composition and the meteorology of TCs remain uncertain. Here we present continuous δ18O and δ2H data in rainfall and water vapour, as well as in discrete rainfall samples, during the passage of TC Ita and relate the evolution in isotopic compositions to local and synoptic scale meteorological observations. High-resolution data revealed a close relationship between isotopic compositions and cyclonic features such as spiral rainbands, periods of stratiform rainfall and the arrival of subtropical and tropical air masses with changing oceanic and continental moisture sources. The isotopic compositions in discrete rainfall samples were remarkably constant along the ~450 km overland path of the cyclone when taking into account the direction and distance to the eye of the cyclone at each sampling time. Near simultaneous variations in δ18O and δ2H values in rainfall and vapour and a near-equilibrium rainfall-vapour isotope fractionation indicates strong isotopic exchange between rainfall and surface inflow of vapour during the approach of the cyclone. In contrast, after the passage of spiral rainbands close to the eye of the cyclone, different moisture sources for rainfall and vapour are reflected in diverging d-excess values. High-resolution isotope studies of modern TCs refine the interpretation of stable isotope signatures found in speleothems and other paleo archives and should aim to further investigate the influence of cyclone intensity and longevity on the isotopic composition of associated rainfall.

  5. Stable Isotope Anatomy of Tropical Cyclone Ita, North-Eastern Australia, April 2014

    PubMed Central

    Munksgaard, Niels C.; Zwart, Costijn; Kurita, Naoyuki; Bass, Adrian; Nott, Jon; Bird, Michael I.

    2015-01-01

    The isotope signatures registered in speleothems during tropical cyclones (TC) provides information about the frequency and intensity of past TCs but the precise relationship between isotopic composition and the meteorology of TCs remain uncertain. Here we present continuous δ18O and δ2H data in rainfall and water vapour, as well as in discrete rainfall samples, during the passage of TC Ita and relate the evolution in isotopic compositions to local and synoptic scale meteorological observations. High-resolution data revealed a close relationship between isotopic compositions and cyclonic features such as spiral rainbands, periods of stratiform rainfall and the arrival of subtropical and tropical air masses with changing oceanic and continental moisture sources. The isotopic compositions in discrete rainfall samples were remarkably constant along the ~450 km overland path of the cyclone when taking into account the direction and distance to the eye of the cyclone at each sampling time. Near simultaneous variations in δ18O and δ2H values in rainfall and vapour and a near-equilibrium rainfall-vapour isotope fractionation indicates strong isotopic exchange between rainfall and surface inflow of vapour during the approach of the cyclone. In contrast, after the passage of spiral rainbands close to the eye of the cyclone, different moisture sources for rainfall and vapour are reflected in diverging d-excess values. High-resolution isotope studies of modern TCs refine the interpretation of stable isotope signatures found in speleothems and other paleo archives and should aim to further investigate the influence of cyclone intensity and longevity on the isotopic composition of associated rainfall. PMID:25742628

  6. Modeling the dynamics of stable isotope tissue-diet enrichment.

    PubMed

    Remien, Christopher H

    2015-02-21

    Reconstructions of dietary composition and trophic level from stable isotope measurements of animal tissue rely on predictable offsets of stable isotope ratios from diet to tissue. Physiological processes associated with metabolism shape tissue stable isotope ratios, and as such the spacing between stable isotope ratios of diet and tissue may be influenced by processes such as growth, nutritional stress, and disease. Here, we develop a model of incorporation stable isotopes in diet to tissues by coupling stable isotope dynamics to a model of macronutrient energy metabolism. We use the model to explore the effect of changes in dietary intake, both composition and amount, and in energy expenditure, on body mass and carbon and nitrogen stable isotope ratios of tissue.

  7. Stable oxygen isotope variability in two contrasting glacier river catchments in Greenland

    NASA Astrophysics Data System (ADS)

    Yde, Jacob C.; Knudsen, Niels T.; Steffensen, Jørgen P.; Carrivick, Jonathan L.; Hasholt, Bent; Ingeman-Nielsen, Thomas; Kronborg, Christian; Larsen, Nicolaj K.; Mernild, Sebastian H.; Oerter, Hans; Roberts, David H.; Russell, Andrew J.

    2016-03-01

    Analysis of stable oxygen isotope18O) characteristics is a useful tool to investigate water provenance in glacier river systems. In order to attain knowledge on the diversity of δ18O variations in Greenlandic rivers, we examined two contrasting glacierised catchments disconnected from the Greenland Ice Sheet (GrIS). At the Mittivakkat Gletscher river, a small river draining a local temperate glacier in southeast Greenland, diurnal oscillations in δ18O occurred with a 3 h time lag to the diurnal oscillations in run-off. The mean annual δ18O was -14.68 ± 0.18 ‰ during the peak flow period. A hydrograph separation analysis revealed that the ice melt component constituted 82 ± 5 % of the total run-off and dominated the observed variations during peak flow in August 2004. The snowmelt component peaked between 10:00 and 13:00 local time, reflecting the long travel time and an inefficient distributed subglacial drainage network in the upper part of the glacier. At the Kuannersuit Glacier river on the island Qeqertarsuaq in west Greenland, the δ18O characteristics were examined after the major 1995-1998 glacier surge event. The mean annual δ18O was -19.47 ± 0.55 ‰. Despite large spatial variations in the δ18O values of glacier ice on the newly formed glacier tongue, there were no diurnal oscillations in the bulk meltwater emanating from the glacier in the post-surge years. This is likely a consequence of a tortuous subglacial drainage system consisting of linked cavities, which formed during the surge event. Overall, a comparison of the δ18O compositions from glacial river water in Greenland shows distinct differences between water draining local glaciers and ice caps (between -23.0 and -13.7 ‰) and the GrIS (between -29.9 and -23.2 ‰). This study demonstrates that water isotope analyses can be used to obtain important information on water sources and the subglacial drainage system structure that is highly desired for understanding glacier hydrology.

  8. Stable Cl And O Isotope Ratios Of Anthropogenic And Natural Perchlorates

    NASA Astrophysics Data System (ADS)

    Beloso, A.; Sturchio, N. C.; Böhlke, J.; Gu, B.; Horita, J.; Brown, G.; Hatzinger, P.

    2004-12-01

    Perchlorate (ClO4-) in aqueous systems, even in low concentrations, is recognized to have potential human health risks. The drinking and irrigation water supplies of millions of people in the U.S. have recently been found to be contaminated with perchlorate, and this problem continues to become even more widespread. Perchlorate, as a highly soluble and relatively inert anion, tends to persist over long time periods and its removal by conventional water treatment technologies is difficult and expensive. Many known sources of perchlorate contamination are anthropogenic, resulting from its extensive use as an oxidizer component in solid propellants for missiles, rockets, and fireworks. However, certain fertilizers derived from Chilean nitrate evaporate deposits are known to contain a low percentage of perchlorate (<0.5%) that may contaminate groundwater. New isotopic evidence provides insights on the possible natural sources of perchlorate in surface and ground waters. Stable isotope ratios of Cl and O can now be used to determine whether the source of perchlorates in a given area is natural or anthropogenic. Microbial perchlorate reduction has a large (˜15 per mil) kinetic isotope effect, and this may be used to identify whether natural attenuation of perchlorate is occurring. Anthropogenic perchlorate salts in milligram amounts are readily analyzed for 37Cl and 18O isotopes. Extracting an isotopically measurable amount of perchlorate from natural waters, which are usually within ppb range of concentrations, is a challenge. But with the use of a new class of highly-selective bifunctional anion exchange resins, recovery of trace amounts of perchlorate for accurate isotopic analysis has been demonstrated. Isotopic characterization is being conducted on anthropogenic perchlorate reagents, natural perchlorate-bearing salt deposits, and perchlorate-bearing groundwaters. Significant and consistent isotopic differences in both the Cl and O isotope ratios between

  9. Stable Vanadium Isotope Fractionation at High Temperatures

    NASA Astrophysics Data System (ADS)

    Prytulak, J.; Parkinson, I. J.; Savage, P. S.; Nielsen, S. G.; Halliday, A. N.

    2011-12-01

    Vanadium is a redox sensitive transition metal existing in multiple valence states at terrestrial conditions. Stable vanadium isotopes (reported as δ51V in % relative to an Alfa Aesar standard [1]) are a potentially powerful tracer of oxidation-reduction processes. However, the determination of δ51V is analytically challenging, primarily due to the extreme abundance ratio between the only two stable isotopes (51V/50V ~ 400) and, also, significant isobaric interferences of 50Ti and 50Cr on the minor 50V isotope. We have developed the first method able to determine δ51V to a precision (2 s.d. ~ 0.15%, [1,2]) that enables application of this isotope system to geological processes. To usefully investigate high temperature processes using vanadium isotopes, knowledge of the isotope composition and range of values present in the ambient mantle is required. Here we discuss the first δ51V measured in igneous materials encompassing peridotites, MORB, and primitive mantle-derived melts such as picrites. This first dataset provides a preliminary reconnaissance of the magnitude of natural fractionation. We find little isotope fractionation in suites of peridotites and MORB (< 0.5 %). However, the small but analytically significant variation appears to be related to secondary processes, with extremely altered peridotites consistently displaying slightly heavier isotope compositions. We find no resolvable δ51V variation between fresh MORB glass and fresh peridotite. Intriguingly, a suite of subduction-related peridotites from the Mariana forearc, previously characterized for fO2 [3], do not display the predicted co-variation between δ51V and fO2, but instead also have compositions identical to MORB glass. This nominally supports recent indications that there is limited difference in the oxygen fugacity of the MORB source and the subarc mantle wedge [e.g., 4, 5]. Finally, we observe large δ51V variations (~ 2 %) in a suite of evolving lavas from Hekla volcano, Iceland

  10. Reconstruction of drip-water δ18O based on calcite oxygen and clumped isotopes of speleothems from Bunker Cave (Germany)

    NASA Astrophysics Data System (ADS)

    Kluge, T.; Affek, H. P.; Marx, T.; Aeschbach-Hertig, W.; Riechelmann, D. F. C.; Scholz, D.; Riechelmann, S.; Immenhauser, A.; Richter, D. K.; Fohlmeister, J.; Wackerbarth, A.; Mangini, A.; Spötl, C.

    2012-07-01

    The geochemical signature of many speleothems used for reconstruction of past continental climates is affected by kinetic isotope fractionation. This limits quantitative paleoclimate reconstruction and, in cases where the kinetic fractionation varies with time, also affects relative paleoclimate interpretations. In carbonate archive research, clumped isotope thermometry is typically used as proxy for absolute temperatures. In the case of speleothems, however, clumped isotopes provide a sensitive indicator for disequilibrium effects. The extent of kinetic fractionation co-varies in Δ47 and δ18O so that it can be used to account for disequilibrium in δ18O and to extract the past drip-water composition. Here we apply this approach to stalagmites from Bunker Cave (Germany) and calculate drip-water δ18Ow values for the Eemian, Marine Isotope Stage (MIS) 3, and the Holocene, relying on independent temperature estimates and accounting for disequilibrium. Applying the co-variation method to modern calcite precipitates yields drip-water δ18Ow values in agreement with modern cave drip-water δ18Ow of -7.9 ± 0.3‰, despite large and variable disequilibrium effects in both calcite δ18Oc and Δ47. Reconstructed paleo-drip-water δ18Ow values are lower during colder periods (e.g., MIS 3: -8.5 ± 0.4‰ and the early Holocene at 11 kyr: -9.3 ± 0.1‰) and show higher values during warmer climatic periods (e.g., the Eemian: -7.5 ± 0.2‰ and the Holocene Climatic Optimum: -7.2 ± 0.3‰). This new approach offers a unique possibility for quantitative climate reconstruction including the assessment of past hydrological conditions while accounting for disequilibrium effects.

  11. Multivariate Stable Isotope Analysis to Determine Linkages between Benzocaine Seizures

    NASA Astrophysics Data System (ADS)

    Kemp, H. F.; Meier-Augenstein, W.; Collins, M.; Salouros, H.; Cunningham, A.; Harrison, M.

    2012-04-01

    In July 2010, a woman was jailed for nine years in the UK after the prosecution successfully argued that attempting to import a cutting agent was proof of involvement in a conspiracy to supply Cocaine. That landmark ruling provided law enforcement agencies with much greater scope to tackle those involved in this aspect of the drug trade, specifically targeting those importing the likes of benzocaine or lidocaine. Huge quantities of these compounds are imported into the UK and between May and August 2010, four shipments of Benzocaine amounting to more then 4 tons had been seized as part of Operation Kitley, a joint initiative between the UK Border Agency and the Serious Organised Crime Agency (SOCA). By diluting cocaine, traffickers can make it go a lot further for very little cost, leading to huge profits. In recent years, dealers have moved away from inert substances, like sugar and baby milk powder, in favour of active pharmaceutical ingredients (APIs), including anaesthetics like Benzocaine and Lidocaine. Both these mimic the numbing effect of cocaine, and resemble it closely in colour, texture and some chemical behaviours, making it easier to conceal the fact that the drug has been diluted. API cutting agents have helped traffickers to maintain steady supplies in the face of successful interdiction and even expand the market in the UK, particularly to young people aged from their mid teens to early twenties. From importation to street-level, the purity of the drug can be reduced up to a factor of 80 and street level cocaine can have a cocaine content as low as 1%. In view of the increasing use of Benzocaine as cutting agent for Cocaine, a study was carried out to investigate if 2H, 13C, 15N and 18O stable isotope signatures could be used in conjunction with multivariate chemometric data analysis to determine potential linkage between benzocaine exhibits seized from different locations or individuals to assist with investigation and prosecution of drug

  12. High-resolution analysis of Quaternary calcretes: a coupled stable isotope and micromorphological approach

    NASA Astrophysics Data System (ADS)

    Adamson, Kathryn; Candy, Ian; Whitfield, Liz

    2015-04-01

    Pedogenic calcretes are abundant in arid and semi-arid regions, and they are widely used as proxy records of palaeoclimatic change. Calcrete oxygen (δ18O) and carbon (δ13C) isotopic signatures are indicative of temperature, aridity, or vegetation at the time of calcrete formation. Their microfabrics also reflect carbonate formation mechanisms in response to the prevailing environmental conditions. Many studies have explored calcrete micromorphology or stable isotope composition, but these techniques have not yet been applied simultaneously. This co-analysis is important as it allows us to establish whether calcrete morphology directly reflects environmental change. This study tests the potential of combining these analyses to examine the relationships between calcrete microfabrics, their isotopic signals, and Quaternary climate change. Calcretes from four river terraces of the Rio Alias in southeast Spain have been analysed in detail. On the basis of morphostratigraphic correlation (Maher et al., 2007) and Uranium-series ages (Candy et al., 2005), these span the period from 304 ± 26 ka (MIS 9) to the Holocene. The oldest profiles have therefore been exposed to multiple glacial-interglacial cycles. A total of 37 micromorphological profiles have been used to extract stable oxygen and carbon isotopic indicators from 77 microfacies. The morphological and isotopic complexity of the calcrete profiles increases with progressive age. The oldest samples display multiple calcretisation phases, and their microfabrics have a larger isotopic range than the younger samples. Alpha (non-biogenic) fabrics have higher δ13C and δ18O values than beta (biogenic) fabrics. Strong positive covariance between δ13C and δ18O within all profiles suggests that both isotopes are responding to the same environmental parameter. We suggest that this is relative aridity. The study demonstrates that the detailed co-analysis of calcrete micromorphology and stable isotope signatures allows

  13. General statistical framework for quantitative proteomics by stable isotope labeling.

    PubMed

    Navarro, Pedro; Trevisan-Herraz, Marco; Bonzon-Kulichenko, Elena; Núñez, Estefanía; Martínez-Acedo, Pablo; Pérez-Hernández, Daniel; Jorge, Inmaculada; Mesa, Raquel; Calvo, Enrique; Carrascal, Montserrat; Hernáez, María Luisa; García, Fernando; Bárcena, José Antonio; Ashman, Keith; Abian, Joaquín; Gil, Concha; Redondo, Juan Miguel; Vázquez, Jesús

    2014-03-01

    The combination of stable isotope labeling (SIL) with mass spectrometry (MS) allows comparison of the abundance of thousands of proteins in complex mixtures. However, interpretation of the large data sets generated by these techniques remains a challenge because appropriate statistical standards are lacking. Here, we present a generally applicable model that accurately explains the behavior of data obtained using current SIL approaches, including (18)O, iTRAQ, and SILAC labeling, and different MS instruments. The model decomposes the total technical variance into the spectral, peptide, and protein variance components, and its general validity was demonstrated by confronting 48 experimental distributions against 18 different null hypotheses. In addition to its general applicability, the performance of the algorithm was at least similar than that of other existing methods. The model also provides a general framework to integrate quantitative and error information fully, allowing a comparative analysis of the results obtained from different SIL experiments. The model was applied to the global analysis of protein alterations induced by low H₂O₂ concentrations in yeast, demonstrating the increased statistical power that may be achieved by rigorous data integration. Our results highlight the importance of establishing an adequate and validated statistical framework for the analysis of high-throughput data.

  14. Stable isotope distribution in continental Maastrichtian vertebrates from the Haţeg Basin, South Carpathians

    NASA Astrophysics Data System (ADS)

    Bojar, Ana-Voica; Csiki, Zoltan; Grigorescu, Dan

    2010-05-01

    The oxygen isotopic compositions of biogenic apatite from crocodiles, turtles and dinosaurs, and their relationship to climate and physiology have been evidenced by several studies (Barrick and Showers, 1995; Kolodny et al., 1996; Barrick et al., 1999; Fricke and Rogers, 2000; Stoskopf et al., 2001; Straight et al., 2004; Amiot et al., 2007). To date, few attempts have been made to correlate the enamel d13C to dietary resources of dinosaurs (Bocherens et al., 1988; Stanton Thomas and Carlson, 2004; Fricke and Pearson, 2008; Fricke, et al., 2008). One additional complication is that for dinosaurs, the d18O of enamel phosphate depends on both body water and variations in body temperature. Several studies addressed the issue of endothermy vs. ectothermy of fossil vertebrates by studying inter- and intra-bone and enamel isotopic variability (Barrick and Showers, 1994, 1995; Barrick et al., 1996; 1998; Fricke and Rogers, 2000). More recent investigations provided evidence for inter-tooth temporal variations and related them to seasonality and/or changes in physiology (Straight et al., 2004; Stanton Thomas and Carlson, 2004). The main objectives of this study are to extract palaeoclimatic information considering, beside lithofacial characteristics and the isotopic distribution of carbonates formed in paleosols, the stable isotope composition of vertebrate remains from the Haţeg Basin. We also sampled several teeth along their growth axis in order to get further information about growth rates and the amplitude of isotopic variation. Located in the South Carpathians in Romania, the Haţeg Basin contains a thick sequence of Maastrichtian continental deposits yielding a rich dinosaur and mammalian fauna. Stable isotope analyses of both calcretes and dinosaur, crocodilian and turtle remains from two localities (Tuştea and Sibişel) were integrated in order to reconstruct environmental conditions during the Maastrichtian time and to gain further insights into the metabolism

  15. Fidelity of Stable Oxygen Isotope Ratios as Environmental Recorders Using Multiple Coral Cores From Coastal Kenya

    NASA Astrophysics Data System (ADS)

    Naish, T.; Carter, B.; Abbott, S.; Field, B.; Zhu, H.; Wilson, G.; Alloway, B.; Edwards, S.; Pillans, B.; Barker, A.; Niessen, F.; Maslen, G.; Beu, A.; Fleitmann, D.; Dunbar, R. B.; Mucciarone, D. A.

    2004-12-01

    Climate variability in the western equatorial Indian Ocean reflects the combined influence of seasonally changing sea surface temperature (SST), ocean currents, and monsoon circulation, as well as inter-annual to -decadal variability associated with ENSO in the Pacific. However, the Indian Ocean also exhibits variability that appears unrelated to ENSO in the Pacific. The nature of interactions between air-sea variability in the Indian and Pacific oceans is not yet fully resolved, in part because of the lack of long-term, high-resolution SST records from key localities in the Indian Ocean. Such records are now being obtained using oxygen isotope profiles measured on corals from East Africa, Indonesia, Australia, and Indian Oceania (Maldives, Seychelles), with the longest coral-based time series from Malindi, Kenya, covering the last 300 years at near-monthly resolution. The value of these developing coral records depends on the fidelity with which they record regional climate variability. In order to assess the fidelity of oxygen isotope ratios (\\delta18O) in Indian Ocean corals as a proxy for sea surface temperature, we have generated stable isotopic time series from multiple Porites lutea coral heads collected along the coast of Kenya. Coral-based isotopic paleoclimatology is labor and time-intensive so detailed analyses using multiple coral heads from different sites within a region are extremely rare. Most published records are produced from a single coral head, yet questions have been raised about the accuracy of such records. To address such concerns, near-monthly resolution isotopic profiles, spanning 10 to 50 years prior to 1997, were measured on a total of 8 cores from five sites along a north-south transect between 2° and 4° S (Kiwayu: 2° 2'S, 41° 2'E, Malindi: 3° 14'S, 40° 8'E, Watamu: 3° 23'S, 39° 52'E, Mombasa: 3° 59'S, 39° 5'E, and Kisite: 4° 43'S, 39° 23'E. Correlations among individual \\delta18O time series (r values range from 0.65 to

  16. Stable Isotope Signatures of Middle Palaeozoic Ahermatypic Rugose Corals – Deciphering Secondary Alteration, Vital Fractionation Effects, and Palaeoecological Implications

    PubMed Central

    Jakubowicz, Michal; Berkowski, Blazej; López Correa, Matthias; Jarochowska, Emilia; Joachimski, Michael; Belka, Zdzislaw

    2015-01-01

    This study investigates stable isotope signatures of five species of Silurian and Devonian deep-water, ahermatypic rugose corals, providing new insights into isotopic fractionation effects exhibited by Palaeozoic rugosans, and possible role of diagenetic processes in modifying their original isotopic signals. To minimize the influence of intraskeletal cements on the observed signatures, the analysed specimens included unusual species either devoid of large intraskeletal open spaces ('button corals': Microcyclus, Palaeocyclus), or typified by particularly thick corallite walls (Calceola). The corals were collected at four localities in the Holy Cross Mountains (Poland), Mader Basin (Morocco) and on Gotland (Sweden), representing distinct diagenetic histories and different styles of diagenetic alteration. To evaluate the resistance of the corallites to diagenesis, we applied various microscopic and trace element preservation tests. Distinct differences between isotopic compositions of the least-altered and most-altered skeleton portions emphasise a critical role of material selection for geochemical studies of Palaeozoic corals. The least-altered parts of the specimens show marine or near-marine stable isotope signals and lack positive correlation between δ13C and δ18O. In terms of isotopic fractionation mechanisms, Palaeozoic rugosans must have differed considerably from modern deep-water scleractinians, typified by significant depletion in both 18O and 13C, and pronounced δ13C-δ18O co-variance. The fractionation effects exhibited by rugosans seem similar rather to the minor isotopic effects typical of modern non-scleractinian corals (octocorals and hydrocorals). The results of the present study add to growing evidence for significant differences between Scleractinia and Rugosa, and agree with recent studies indicating that calcification mechanisms developed independently in these two groups of cnidarians. Consequently, particular caution is needed in using

  17. Monitoring water stable isotope composition in soils using gas-permeable tubing and infrared laser absorption spectroscopy

    NASA Astrophysics Data System (ADS)

    Rothfuss, Youri; Vereecken, Harry; Brüggemann, Nicolas

    2013-04-01

    The water stable isotopologues 1H2H16O and 1H218O are powerful tracers of processes occurring in nature. Their slightly different masses as compared to the most abundant water isotopologue (1H216O) affect their thermodynamic (e.g. during chemical equilibrium reactions or physical phase transitions with equilibration) and kinetic (liquid and vapor phases transport processes and chemical reactions without equilibration) properties. This results in measurable differences of the isotopic composition of water within or between the different terrestrial ecosystem compartments (i.e. sub-soil, soil, surface waters, plant, and atmosphere). These differences can help addressing a number of issues, among them water balance closure and flux partitioning from the soil-plant-atmosphere continuum at the field to regional scales. In soils particularly, the isotopic composition of water (δ2H and δ18O) provides qualitative information about whether water has only infiltrated or already been re-evaporated since the last rainfall event or about the location of the evaporation front. From water stable isotope composition profiles measured in soils, it is also possible, under certain hypotheses, to derive quantitative information such as soil evaporation flux and the identification of root water uptake depths. In addition, water stable isotopologues have been well implemented into physically based Soil-Vegetation-Atmosphere Transfer models (e.g. SiSPAT-Isotope; Soil-Litter iso; TOUGHREACT) and have demonstrated their potential. However, the main disadvantage of the isotope methodology is that, contrary to other soil state variables that can be monitored over long time periods, δ2H and δ18O are typically analyzed following destructive sampling. Here, we present a non-destructive method for monitoring soil liquid water δ2H and δ18O over a wide range of water availability conditions and temperatures by sampling and measuring water vapor equilibrated with soil water using gas

  18. Stable isotopes in fish as indicators of habitat use

    EPA Science Inventory

    In our isotopic studies of fish in Oregon Coast Range streams we have found stable isotopes of carbon, oxygen and sulfur to be surprisingly useful in identifying and discriminating specific habitat or tributary use by a variety of fish species. Stable isotopes of carbon can be u...

  19. Embryotoxicity of stable isotopes and use of stable isotopes in studies of teratogenetic mechanisms

    SciTech Connect

    Spielmann, H.; Nau, H.

    1986-07-01

    Experiments on teratogenic effects of stable isotopes from our own and other laboratories are evaluated. In the first series of investigations, the enrichment of the stable isotope /sup 13/C derived from U-/sup 13/C-glucose was studied in mouse embryos at various stages of development, including limb buds in organ culture. Preimplantation mouse embryos incubated in vitro in /sup 13/C-enriched medium for 48 hours showed normal development during subsequent differentiation in vitro and also in vivo after embryo transfer to faster mothers. These embryos were 15% to 20% enriched in /sup 13/C. Administration of U-13-C-glucose to pregnant mice during organogenesis led to an increase of the absolute /sup 13/C content of the embryo for several days after the end of isotope administration, whereas the enrichment in maternal tissue decreased. No alterations of embryonic development were detected due to stable isotope enrichment. Development of cultured mouse limb buds was unaffected by incubation with 82 mol% U-/sup 13/C-glucose as judged from morphologic and biochemical criteria. The second part of the article describes the value of deuterium-labeled drugs as probes into the mechanism of activation of teratogenic metabolites. A comparison of the pharmacokinetics as well as the teratogenicity between cyclophosphamide and some specific deuterium-labeled analogues showed that the isotope effect observed can be related to a particular metabolic pathway crucial for teratogenic activation by this drug.

  20. Stable Nitrogen and Oxygen Isotope Analysis of Nitrate using Denitrifying Bacteria

    NASA Astrophysics Data System (ADS)

    Edenburn, L.; Michalski, G. M.

    2009-12-01

    tube into both O2 and N2 using techniques adapted from Cascotti and Kaiser. Our instrument utilizes an extended 11-cup multi-collector feature which does not require a peak jump during analysis on the continuous flow IRMS. Although this is not the first method to study independent measurements of δ18O, δ17O, δ15N, or Δ17O, this is first technique that simultaneously detects the stable isotope composition of oxygen and nitrogen in a given nitrate sample. Tests of the impact on isotopic composition by pre-concentration methods have been performed including freeze-drying/evaporation, column chromatography and ion chromatography.

  1. A reassessment of isotopic equilibrium (Δ47 and δ18O) in the Laghetto Basso pool carbonates

    NASA Astrophysics Data System (ADS)

    Daëron, M.; Drysdale, R.; Blamart, D.; Genty, D.; Zanchetta, G.

    2013-12-01

    To the best of our current knowledge, the overwhelming majority of modern speleothems have Δ47 values which differ significantly from those predicted for thermodynamic equilibrium. The extent to which these differences may vary temporally and spatially is still an open issue, precluding a straightforward application of clumped isotopes paleothermometry to speleothem records. Here we report on the recent results of a reassessment of isotopic equilibrium in the Laghetto Basso pool carbonates (Antro del Corchia cave, NW Italy), which offer excellent a priori conditions for equilibrium carbonate precipitation and provide a continuous or quasi-continuous isotopic record of the past million years.

  2. Stable isotope analysis of precipitation samples obtained via crowdsourcing reveals the spatiotemporal evolution of Superstorm Sandy.

    PubMed

    Good, Stephen P; Mallia, Derek V; Lin, John C; Bowen, Gabriel J

    2014-01-01

    Extra-tropical cyclones, such as 2012 Superstorm Sandy, pose a significant climatic threat to the northeastern United Sates, yet prediction of hydrologic and thermodynamic processes within such systems is complicated by their interaction with mid-latitude water patterns as they move poleward. Fortunately, the evolution of these systems is also recorded in the stable isotope ratios of storm-associated precipitation and water vapor, and isotopic analysis provides constraints on difficult-to-observe cyclone dynamics. During Superstorm Sandy, a unique crowdsourced approach enabled 685 precipitation samples to be obtained for oxygen and hydrogen isotopic analysis, constituting the largest isotopic sampling of a synoptic-scale system to date. Isotopically, these waters span an enormous range of values (> 21‰ for δ(18)O, > 160‰ for δ(2)H) and exhibit strong spatiotemporal structure. Low isotope ratios occurred predominantly in the west and south quadrants of the storm, indicating robust isotopic distillation that tracked the intensity of the storm's warm core. Elevated values of deuterium-excess (> 25‰) were found primarily in the New England region after Sandy made landfall. Isotope mass balance calculations and Lagrangian back-trajectory analysis suggest that these samples reflect the moistening of dry continental air entrained from a mid-latitude trough. These results demonstrate the power of rapid-response isotope monitoring to elucidate the structure and dynamics of water cycling within synoptic-scale systems and improve our understanding of storm evolution, hydroclimatological impacts, and paleo-storm proxies.

  3. Oxygen and carbon stable isotopes in coast redwood tree rings respond to spring and summer climate signals

    NASA Astrophysics Data System (ADS)

    Johnstone, James A.; Roden, John S.; Dawson, Todd E.

    2013-12-01

    variability in the oxygen and carbon isotope composition of tree ring cellulose was investigated in coast redwood (Sequoia sempervirens) from three sites in coastal Northern California. Middle and late wood samples from annual tree rings were compared to regional climate indices and gridded ocean-atmosphere fields for the years 1952-2003. The strongest climate-isotope relationship (r = 0.72) was found with summer (June-September) daily maximum temperature and middle wood δ13, which also responds positively to coastal sea surface temperature and negatively to summer low cloud frequency. Late wood δ18O reflects a balance between 18O-enriched summer fog drip and depleted summer rainwater, while a combined analysis of late wood δ18O and δ13C revealed sensitivity to the sign of summer precipitation anomalies. Empirical orthogonal function analysis of regional summer climate indices and coast redwood stable isotopes identified multivariate isotopic responses to summer fog and drought that correspond to atmospheric circulation anomalies over the NE Pacific and NW U.S. The presence of regional climate signals in coast redwood stable isotope composition, consistent with known mechanistic processes and prior studies, offers the potential for high-resolution paleoclimate reconstructions of the California current system from this long-lived tree species.

  4. /sup 18/O isotope effect in /sup 13/C nuclear magnetic resonance spectroscopy. Part 9. Hydrolysis of benzyl phosphate by phosphatase enzymes and in acidic aqueous solutions

    SciTech Connect

    Parente, J.E.; Risley, J.M.; Van Etten, R.L.

    1984-12-26

    The /sup 18/O isotope-induced shifts in /sup 13/C and /sup 31/P nuclear magnetic resonance (NMR) spectroscopy were used to establish the position of bond cleavage in the phosphatase-catalyzed and acid-catalyzed hydrolysis reactions of benzyl phosphate. The application of the /sup 18/O-isotope effect in NMR spectroscopy affords a continuous, nondestructive assay method for following the kinetics and position of bond cleavage in the hydrolytic process. The technique provides advantages over most discontinuous methods in which the reaction components must be isolated and converted to volatile derivatives prior to analysis. In the present study, (..cap alpha..-/sup 13/C,ester-/sup 18/O)benzyl phosphate and (ester-/sup 18/O)benzyl phosphate were synthesized for use in enzymatic and nonenzymatic studies. Hydrolysis reactions catalyzed by the alkaline phosphatase from E. coli and by the acid phosphatases isolated from human prostate and human liver were all accompanied by cleavage of the substrate phosphorus-oxygen bond consistent with previously postulated mechanisms involving covalent phosphoenzyme intermediates. An extensive study of the acid-catalyzed hydrolysis of benzyl phosphate at 75/sup 0/C revealed that the site of bond cleavage is dependent on pH. At pH less than or equal to 1.3, the hydrolysis proceeds with C-O bond cleavage; at 1.3 < pH < 2.0, there is a mixture of C-O and P-O bond scission, the latter progressively predominating as the pH is raised; at pH greater than or equal to 2.0, the hydrolysis proceeds with exclusive P-O bond scission. (S)-(+)-(..cap alpha..-/sup 2/H)Benzyl phosphate was also synthesized. Hydrolysis of this chiral benzyl derivative demonstrated that the acid-catalyzed C-O bond scission of benzyl phosphate proceeds by an A-1 (S/sub N/1) mechanism with 70% racemization and 30% inversion at carbon. 37 references, 4 figures, 2 tables.

  5. Estimating groundwater exchange with lakes: 1. The stable isotope mass balance method

    USGS Publications Warehouse

    Krabbenhoft, David P.; Bowser, Carl J.; Anderson, Mary P.; Valley, John W.

    1990-01-01

    Groundwater inflow and outflow contributions to the hydrologic budget of lakes can be determined using a stable isotope (18O/16O) mass balance method. The stable isotope method provides a way of integrating the spatial and temporal complexities of the flow field around a lake, thereby offering an appealing alternative to the traditional time and labor intensive methods using seepage meters and an extensive piezometer network. In this paper the method is applied to a lake in northern Wisconsin, demonstrating that it can be successfully applied to lakes in the upper midwest where thousands of similar lakes exist. Inflow and outflow rates calculated for the Wisconsin lake using the isotope mass balance method are 29 and 54 cm/yr, respectively, which compare well to estimates, derived independently using a three-dimensional groundwater flow and solute transport model, of 20 and 50 cm/yr. Such a favorable comparison lends confidence to the use of the stable isotope method to estimate groundwater exchange with lakes. In addition, utilization of stable isotopes in studies of groundwater-lake systems lends insight into mixing processes occurring in the unsaturated zone and in the aquifer surrounding the lake and verifies assumed flow paths based on head measurements in piezometers.

  6. Stable isotope study of precipitation and cave drip water in Florida (USA): implications for speleothem-based paleoclimate studies.

    PubMed

    Onac, Bogdan P; Pace-Graczyk, Kali; Atudirei, Viorel

    2008-06-01

    Stable isotopes of hydrogen and oxygen were used to examine how the isotopic signal of meteoric water is modified as it travels through soil and epikarst into two caves in Florida. Surface and cave water samples were collected every week from February 2006 until March 2007. The isotopic composition of precipitation at the investigated sites is highly variable and shows little seasonal control. The delta18O vs. delta2H plot shows a mixing line having a slope of 5.63, suggesting evaporation effects dominate the isotopic composition of most rainfall events of less than 8 cm/day, as indicated by their low d-excess values. The delta18O values of the drip water show little variability (<0.6 per thousand), which is loosely tied to local variations in the seasonal amount of precipitation. This is only seen during wintertime at the Florida Caverns site. The lag time of over two months and the lack of any relationship between rainfall amount and the increase in drip rate indicate a dominance of matrix flow relative to fracture/conduit flow at each site. The long residence time of the vadose seepage waters allows for an effective isotopic homogenisation of individual and seasonal rainfall events. We find no correlation between rainfall and drip water delta18O at any site. The isotopic composition of drip water in both caves consistently tends to resemble the amount-weighted monthly mean rainfall input. This implies that the delta18O of speleothems from these two caves in Florida cannot record seasonal cycle in rainfall delta18O, but are suitable for paleoclimate reconstructions at inter-annual time scales.dagger. PMID:18569187

  7. Assessing sources of nitrate contamination in the Shiraz urban aquifer (Iran) using the δ(15)N and δ(18)O dual-isotope approach.

    PubMed

    Amiri, Haleh; Zare, Mohammad; Widory, David

    2015-01-01

    Nitrate ([Formula: see text]) is one of the major threats to the quality of the drinking water taken from the Shiraz aquifer. This aquifer undergoes high anthropogenic pressures from multiple local urban (including uncontrolled sewage systems), agricultural and industrial activities, resulting in [Formula: see text] concentrations as high as 149 mg L(-1), well above the 50 mg L(-1) guideline defined by the World Health Organisation. We coupled here classical chemical and dual isotope (δ(15)N and δ(18)O of [Formula: see text]) approaches trying to characterize sources and potential processes controlling the budget of this pollutant. Chemical data indicate that nitrate in this aquifer is explained by distinct end-members: while mineral fertilizers isotopically show to have no impact, our isotope approach identifies natural soil nitrification and organic [Formula: see text] (manure and/or septic waste) as the two main contributors. Isotope data suggest that natural denitrification may occur within the aquifer, but this conclusion is not supported by the study of other chemical parameters.

  8. Comparison between IRMS and CRDS methods in the determination of isotopic ratios 2H/1H and 18O/16O in water

    NASA Astrophysics Data System (ADS)

    Santos, T. H. R.; Zucchi, M. R.; Lemaire, T.; Azevedo, A. E. G.

    2013-05-01

    Traditionally, the method used for measuring the isotope ratios is the Isotope Ratio Mass Spectrometers (IRMS). A new method has been used to determine the isotopic abundances, the Cavity Ring-Down Spectroscopy (CRDS). It consists of a technique of direct absorption, of high sensitivity, which is based on measuring the absorption ratio, as a function of time, of the light confined in a high finesse optical cavity, instead of the magnitude of light beam absorption. The values of 18O/16O and D/H ratios are determined with respect to international standards VSMOW, GISP and SLAP from the International Atomic Energy Agency (IAEA). In this work, the IRMS and CRDS techniques are compared, verifying that the CRDS technique is promising and has some advantages compared to IRMS. It uses a smaller amount of sample, the isotope measurements are made simultaneously from the steam, reducing the analysis time. It also shows good reproducibility and accuracy, and it does not require a preliminary sample preparation.

  9. Assessing sources of nitrate contamination in the Shiraz urban aquifer (Iran) using the δ(15)N and δ(18)O dual-isotope approach.

    PubMed

    Amiri, Haleh; Zare, Mohammad; Widory, David

    2015-01-01

    Nitrate ([Formula: see text]) is one of the major threats to the quality of the drinking water taken from the Shiraz aquifer. This aquifer undergoes high anthropogenic pressures from multiple local urban (including uncontrolled sewage systems), agricultural and industrial activities, resulting in [Formula: see text] concentrations as high as 149 mg L(-1), well above the 50 mg L(-1) guideline defined by the World Health Organisation. We coupled here classical chemical and dual isotope (δ(15)N and δ(18)O of [Formula: see text]) approaches trying to characterize sources and potential processes controlling the budget of this pollutant. Chemical data indicate that nitrate in this aquifer is explained by distinct end-members: while mineral fertilizers isotopically show to have no impact, our isotope approach identifies natural soil nitrification and organic [Formula: see text] (manure and/or septic waste) as the two main contributors. Isotope data suggest that natural denitrification may occur within the aquifer, but this conclusion is not supported by the study of other chemical parameters. PMID:25941866

  10. Reconstruction of drip-water δ18O based on calcite oxygen and clumped isotopes of speleothems from Bunker Cave (Germany)

    NASA Astrophysics Data System (ADS)

    Kluge, T.; Affek, H. P.; Marx, T.; Aeschbach-Hertig, W.; Riechelmann, D. F. C.; Scholz, D.; Riechelmann, S.; Immenhauser, A.; Richter, D. K.; Fohlmeister, J.; Wackerbarth, A.; Mangini, A.; Spötl, C.

    2013-02-01

    The geochemical signature of many speleothems used for reconstruction of past continental climates is affected by kinetic isotope fractionation. This limits quantitative paleoclimate reconstruction and, in cases where the kinetic fractionation varies with time, also affects relative paleoclimate interpretations. In carbonate archive research, clumped isotope thermometry is typically used as proxy for absolute temperatures. In the case of speleothems, however, clumped isotopes provide a sensitive indicator for disequilibrium effects. The extent of kinetic fractionation co-varies in Δ47 and δ18O so that it can be used to account for disequilibrium in δ18O and to extract the past drip-water composition. Here we apply this approach to stalagmites from Bunker Cave (Germany) and calculate drip-water δ18Ow values for the Eemian, MIS3, and the Holocene, relying on independent temperature estimates and accounting for disequilibrium. Applying the co-variation method to modern calcite precipitates yields drip-water δ18Ow values in agreement with modern cave drip-water δ18Ow of -7.9 ± 0.3‰, despite large and variable disequilibrium effects in both calcite δ18Oc and Δ47. Reconstructed paleo-drip-water δ18Ow values are lower during colder periods (e.g., MIS3: -8.6 ± 0.4‰ and the early Holocene at 11 ka: -9.7 ± 0.2‰) and show higher values during warmer climatic periods (e.g., the Eemian: -7.6 ± 0.2‰ and the Holocene Climatic Optimum: -7.2 ± 0.3‰). This new approach offers a unique possibility for quantitative climate reconstruction including the assessment of past hydrological conditions while accounting for disequilibrium effects.

  11. A river based stable isotope record of orographic precipitation: Taurus Mountains, south central Turkey

    NASA Astrophysics Data System (ADS)

    Schemmel, Fabian; Mulch, Andreas; Mikes, Tamás.; Schildgen, Taylor

    2010-05-01

    Reconstructing continental precipitation and vegetation patterns has become one of the most rapidly growing fields in terrestrial paleoclimate research. Furthermore, stable isotopes in precipitation within continental plateau regions represent an increasingly important tool for reconstructing the various effects of uplift related climate change within the world's largest plateau regions. With peak elevations of more than 3,000 m the Taurus Mountains represent the southern margin of the central Anatolian plateau and must have played a pivotal role in controlling the drainage and sedimentation patterns within the plateau interior. However, their surface uplift history remains largely elusive. We sampled a series of tributaries and rivers along the Ermenek valley that crosscuts the Taurus Mountains in Southern Turkey. The aim of this study is to quantify the modern effect of orographic rainout of the Taurus Mountains on the d18O and dD values of river and spring waters and to compare these values to the d18O and dD of recent precipitation gathered by the Global Network of Isotopes in Precipitation (GNIP). Further we try to study the trends of the recent d18O and dD isotopic composition of local rivers and precipitation in the area to create a set of isotopic data that is comparable to isotopic studies on paleosoils and can therefore be used in future paleoaltimetry and paleoclimate studies. We sampled 6 individual rivers during the fall season 2008 to capture mostly groundwater runoff in the south central Taurus Mountains. All sampled rivers belong to the same local drainage system which drains into the Mediterranean Sea. The total elevation difference within the sampling area exceeds 2,000 m and we were able to collect samples over almost 1,800 m of elevation. Our measurements show that both d18O and dD values follow the same basic trend. d18O and dD values decrease systematically with increasing elevation. The lapse rate of d18O is about -2.2 per mil/km, whereas the

  12. Reformulated 17O correction of mass spectrometric stable isotope measurements in carbon dioxide and a critical appraisal of historic 'absolute' carbon and oxygen isotope ratios

    NASA Astrophysics Data System (ADS)

    Kaiser, Jan

    2008-03-01

    Mass-spectrometric stable isotope measurements of CO 2 use molecular ion currents at mass-to-charge ratios m/ z 44, 45 and 46 to derive the elemental isotope ratios n( 13C)/ n( 12C) and n( 18O)/ n( 16O), abbreviated 13C/ 12C and 18O/ 16O, relative to a reference. The ion currents have to be corrected for the contribution of 17O-bearing isotopologues, the so-called ' 17O correction'. The magnitude of this correction depends on the calibrated isotope ratios of the reference. Isotope ratio calibrations are difficult and are therefore a matter of debate. Here, I provide a comprehensive evaluation of the existing 13C/ 12C ( 13R), 17O/ 16O ( 17R) and 18O/ 16O ( 18R) calibrations of the reference material Vienna Standard Mean Ocean Water (VSMOW) and CO 2 generated from the reference material Vienna Pee Dee Belemnite (VPDB) by reaction with 100% H 3PO 4 at 25 °C (VPDB-CO 2). I find 17R/10-6=382.7-2.1+1.7, 18RVSMOW/10 -6 = 2005.20 ± 0.45, 13R/10-6= 11124 ± 45, 17R/10-6=391.1-2.1+1.7 and 18R/10-6=2088.37±0.90. I also rephrase the calculation scheme for the 17O correction completely in terms of relative isotope ratio differences ( δ values). This reveals that only ratios of isotope ratios (namely, 17R/ 13R and 13R17R/ 18R) are required for the 17O correction. These can be, and have been, measured on conventional stable isotope mass spectrometers. I then show that the remaining error for these ratios of isotope ratios can lead to significant uncertainty in the derived relative 13C/ 12C difference, but not for 18O/ 16O. Even though inter-laboratory differences can be corrected for by a common 'ratio assumption set' and/or normalisation, the ultimate accuracy of the 17O correction is hereby limited. Errors of similar magnitude can be introduced by the assumed mass-dependent relationship between 17O/ 16O and 18O/ 16O isotope ratios. For highest accuracy in the 13C/ 12C ratio, independent triple oxygen isotope measurements are required. Finally, I propose an experiment that

  13. STABLE ISOTOPES IN ECOLOGICAL STUDIES: NEW DEVELOPMENTS IN MIXING MODELS

    EPA Science Inventory

    Stable isotopes are increasingly being used as tracers in ecological studies. One application uses isotopic ratios to quantify the proportional contributions of multiple sources to a mixture. Examples include food sources for animals, water sources for plants, pollution sources...

  14. Stable carbon and oxygen isotopic composition of carbonate in fugitive dust in the Chinese Loess Plateau

    NASA Astrophysics Data System (ADS)

    Cao, J. J.; Zhu, C. S.; Chow, J. C.; Liu, W. G.; Han, Y. M.; Watson, J. G.

    Stable C-O isotopic composition of loess samples for TSP, PM 10, PM 2.5, and PM 1 at five sites (Yulin, Yanchi, Huanxian, Luochuan, and Xi'an) in Chinese Loess Plateau are examined. The average δ13C and δ18O abundances were -6.00‰ and -8.30‰ in TSP, -6.05‰ and -8.22‰ in PM 10, -6.07‰ and -8.33‰ in PM 2.5, and -6.00‰ and -8.28‰ in PM 1, respectively. Little differences were found for δ13C and δ18O abundances in four size fractions. The differences of δ13C between the averages of fugitive dust and bulk soil were smaller than 2‰ at five locations, which implied that the isotopic composition of bulk soil (surface soil) can be used as substitute of fugitive dust carbonate in dust source apportion study. The distribution of CO 3-C, δ13C and δ18O in fugitive dust shows that only δ13C is a powerful tracer of source regions. A database about the δ13C distribution in soil carbonate in major source regions of Asian dust was summarized for source apportion study of atmospheric dust.

  15. Characterizing the Hydrologic Impacts of Mountaintop Mining Using Stable Isotopes

    NASA Astrophysics Data System (ADS)

    Zegre, N.; McGuire, K. J.

    2011-12-01

    Despite mountaintop removal mining (MTM) accounting for the largest land-use change in the Appalachian region of the eastern US, its impact on runoff processes is poorly understood. Several devastating floods have been attributed to MTM activities upstream but there is little quantifiable evidence on how MTM impacts mechanisms of streamflow generation and flooding downstream. MTM involves removing the forest, topsoil, and overlying bedrock to gain access to deeper coal seams. Excess rock is pushed into adjacent valley to create valley fills that completely bury headwater streams that permanently alter ecosystem organization and processes. Isotope hydrology can provide process-based information about the temporal and geographic sources of runoff and rainfall-runoff relationships, but these approaches have not been applied in systems undergoing rapid change and typically not at larger landscape scales. In this study we examine runoff generation using stable isotopes of water from Sycamore Creek (27 km2), an undisturbed forested catchment, and White Oak Creek (11 km2), a MTM-impacted catchment, to quantify for the first time how landscape-scale disturbances impact rainfall-runoff relationship and the processes that govern runoff generation. Both catchments are headwaters of the Clear Fork River watershed (163 km2), an extensively mined and recurrent flood-prone watershed in southern West Virginia, USA. Mountaintop mining in White Oak Creek has disturbed 3 km2 (27% of catchment area) to include 10 valley fills comprising ~0.8 km2 (7%). Stream and rainfall were continuously measured at the outlet of each catchment and water samples were collected using Isco automated water samplers to incrementally characterize isotopic variations in 18O and 2H. Streamflow was separated into event and pre-event water using a two-component hydrograph separation model. The total fraction of event/pre-event water for each event was estimated by linear interpolation between incremental

  16. Long Term and High Frequency Non-Destructive Monitoring of Soil Water Stable Isotope Compositions in the Laboratory

    NASA Astrophysics Data System (ADS)

    Rothfuss, Y.; Merz, S.; Pohlmeier, A. J.; Vereecken, H.; Brueggemann, N.

    2014-12-01

    The fate and dynamics of water stable isotopologues (1H2H16O and 1H218O) are currently well implemented into physically based Soil-Vegetation-Atmosphere Transfer (SVAT) models (e.g. Hydrus 1D, SiSPAT-I, Soil-Litter iso, TOUGHREACT). However, contrary to other state variables (e.g., water content and tension) that can be monitored over long periods (e.g., by time-domain reflectometry, capacitive sensing, tensiometry or micro-psychrometry), water stable isotope compositions (δ2H and δ18O) are analyzed following destructive sampling, and thus are available only at a given time. Thus, there are important discrepancies in time resolution between soil water and stable isotope information which greatly limit the insight potential of the latter. Recently however, a technique based on direct infrared laser absorption spectroscopy was developed that allows simultaneous and direct measurements of δ2H and δ18O in water vapor. Here, we present a non-destructive method for monitoring soil liquid δ2H and δ18O by sampling and measuring water vapor equilibrated with soil water using gas-permeable polypropylene tubing and a Cavity Ring-Down laser Spectrometer (CRDS). An acrylic glass column (d=11 cm, h=60 cm) was (i) equipped with temperature and soil water probes in addition to gas-permeable tubing sections at eight different depths, (ii) filled with pure quartz sand, (iii) saturated from the bottom, and (iv) installed on weighing balances and let dry for 250 days. Each day, soil vapor δ2H and δ18O were measured for each depth by purging the soil water vapor sampled in the tubing sections with dry air and analyzing it with a CRDS. Soil liquid water δ2H and δ18O were then inferred from the values measured in the vapor. The experimental setup allowed following the evolution of the soil water δ2H and δ18O profile, which developed as a result of isotope convective capillary rise and back-diffusion of the stable isotope excess at the soil surface due to fractionating soil

  17. Kinetic Fractionation of Stable Isotopes in Carbonates on Mars: Terrestrial Analogs

    NASA Technical Reports Server (NTRS)

    Socki, Richard A.; Gibson, Everett K., Jr.; Golden, D. C.; Ming, Douglas W.; McKay, Gordon A.

    2003-01-01

    An ancient Martian hydrosphere consisting of an alkali-rich ocean would likely produce solid carbonate minerals through the processes of evaporation and/or freezing. We postulate that both (or either) of these kinetically-driven processes would produce carbonate minerals whose stable isotopic compositions are highly fractionated (enriched) with respect to the source carbon. Various scenarios have been proposed for carbonate formation on Mars, including high temperature formation, hydrothermal alteration, precipitation from evaporating brines, and cryogenic formation. 13C and 18O -fractionated carbonates have previously been shown to form kinetically under some of these conditions, ie.: 1) alteration by hydrothermal processes, 2) low temperature precipitation (sedimentary) from evaporating bicarbonate (brine) solutions, and 3) precipitation during the process of cryogenic freezing of bicarbonate-rich fluids. Here we examine several terrestrial field settings within the context of kinetically controlled carbonate precipitation where stable isotope enrichments have been observed.

  18. Applications of stable isotope analysis in mammalian ecology.

    PubMed

    Walter, W David; Kurle, Carolyn M; Hopkins, John B

    2014-01-01

    In this editorial, we provide a brief introduction and summarize the 10 research articles included in this Special Issue on Applications of stable isotope analysis in mammalian ecology. The first three articles report correction and discrimination factors that can be used to more accurately estimate the diets of extinct and extant mammals using stable isotope analysis. The remaining seven applied research articles use stable isotope analysis to address a variety of wildlife conservation and management questions from the oceans to the mountains.

  19. Spatial distribution and temporal variability of stable water isotopes in a large and shallow lake.

    PubMed

    Xiao, Wei; Wen, Xuefa; Wang, Wei; Xiao, Qitao; Xu, Jingzheng; Cao, Chang; Xu, Jiaping; Hu, Cheng; Shen, Jing; Liu, Shoudong; Lee, Xuhui

    2016-01-01

    Stable isotopic compositions of lake water provide additional information on hydrological, meteorological and paleoclimate processes. In this study, lake water isotopic compositions were measured for more than three years in Lake Taihu, a large and shallow lake in southern China, to investigate the isotopic spatial and seasonal variations. The results indicated that (1) the whole-lake mean δ(2)H and δ(18)O values of the lake water varied seasonally from -48.4 ± 5.8 to -25.1 ± 3.2 ‰ and from -6.5 ± 0.9 to -3.5 ± 0.8 ‰, respectively, (2) the spatial pattern of the lake water isotopic compositions was controlled by the direction of water flow and not by local evaporation rate, and (3) using a one-site isotopic measurement to represent the whole-lake mean may result in unreasonable estimates of the isotopic composition of lake evaporation and the lake water residence time in poorly mixed lakes. The original data, documented here as an online supplement, provides a good reference for testing sensitivity of lake water budget to various isotopic sampling strategies. We propose that detailed spatial measurement of lake water isotopic compositions provides a good proxy for water movement and pollutant and alga transports, especially over big lakes. PMID:26983027

  20. Stable isotope studies of nephrite deposits from Fengtien, Taiwan

    NASA Astrophysics Data System (ADS)

    Yui, Tzen-Fu; Yeh, Hsueh-Wen; Lee, Chihming Wang

    1988-03-01

    Metasomatic nephrite deposits ( i.e., rodingites) occur between serpentinites and muscovite-quartz schist in the Fengtien area, eastern Taiwan. The δ 18O values of nephrite range from +4.5 to +5.3%. and the δD values, from -33 to -68%. The narrow range in the δ 18O values and wide variation in the δD values indicate low water/rock ratios and multiple origins of the ambient H 2O during nephrite formation. The ultimate sources of the ambient H 2O are largely sea water for the early nephrite and meteoric water for the late nephrite. The temperature of nephrite formation is 320-420°C: the estimated O-isotopic fractionation between nephrite (tremolite) and serpentine (antigorite) is 1.0 ± 0.2%. in this temperature range. Diopsidefels and epidotite are two other kinds of rodingite in the deposits. The δ 18O values of diopside from diopsidefels range from +3.7 to +4.5%., theδD values of clinozoisite from epidotite range from -31 to -34%. and the δ 18O value of one clinozoisite analyzed is +3.9%. These data suggest that most diopsidefels formed in isotopic equilibrium with nephrite and that clinozoisite was not in isotopic equilibrium with either nephrite or diopsidefels. O-isotope compositions of both nephrite and diopsidefels cannot give conclusive evidence of their parental rocks. Circumstantial evidence, however, implies that the nephrite is derived from serpentinite whereas diopsidefels formed from unaltered ultramafic rocks.

  1. Systematic investigations of the stable Cd isotopes

    NASA Astrophysics Data System (ADS)

    Garrett, P. E.; Green, K. L.; Wood, J. L.; Kulp, W. D.

    2007-10-01

    The Cd nuclei, especially the stable even-even isotopes have been well studied since they were suggested as paradigms of the vibrational, or U(5), limit of the Interacting Boson Model (IBM). In addition to the normal quadrupole phonon states, in many cases suggested up to the three-phonon quintuplet, more deformed 2p4h intruder excitations have been established. Recent investigations with the (n,n^'γ) reaction [1,2,3,4] have provided a wealth of information on the low-lying levels, including many lifetimes not previously known. Deviations in the transition B(E2) values for low-spin states from those expected for U(5) nuclei are observed to appear systematically across the Cd isotopes. We have performed detailed calculations using the IBM-2, and find that these deviations cannot be explained through considered mixings with the intruder excitations or mixed-symmetry states, indicating that some physics is missing in the description of these levels. [1] F. Corminboeuf et al., Phys. Rev. C 63, 014305 (2001).[2] P.E. Garrett et al., Phys. Rev. C 75, 014307 (2007).[3] D. Bandyopadhyay et al., to be published. [4] M. Kadi et al., Phys. Rev. 68, 031306 (2003).

  2. Protease- and Acid-catalyzed Labeling Workflows Employing 18O-enriched Water

    PubMed Central

    Klingler, Diana; Hardt, Markus

    2013-01-01

    Stable isotopes are essential tools in biological mass spectrometry. Historically, 18O-stable isotopes have been extensively used to study the catalytic mechanisms of proteolytic enzymes1-3. With the advent of mass spectrometry-based proteomics, the enzymatically-catalyzed incorporation of 18O-atoms from stable isotopically enriched water has become a popular method to quantitatively compare protein expression levels (reviewed by Fenselau and Yao4, Miyagi and Rao5 and Ye et al.6). 18O-labeling constitutes a simple and low-cost alternative to chemical (e.g. iTRAQ, ICAT) and metabolic (e.g. SILAC) labeling techniques7. Depending on the protease utilized, 18O-labeling can result in the incorporation of up to two 18O-atoms in the C-terminal carboxyl group of the cleavage product3. The labeling reaction can be subdivided into two independent processes, the peptide bond cleavage and the carboxyl oxygen exchange reaction8. In our PALeO (protease-assisted labeling employing 18O-enriched water) adaptation of enzymatic 18O-labeling, we utilized 50% 18O-enriched water to yield distinctive isotope signatures. In combination with high-resolution matrix-assisted laser desorption ionization time-of-flight tandem mass spectrometry (MALDI-TOF/TOF MS/MS), the characteristic isotope envelopes can be used to identify cleavage products with a high level of specificity. We previously have used the PALeO-methodology to detect and characterize endogenous proteases9 and monitor proteolytic reactions10-11. Since PALeO encodes the very essence of the proteolytic cleavage reaction, the experimental setup is simple and biochemical enrichment steps of cleavage products can be circumvented. The PALeO-method can easily be extended to (i) time course experiments that monitor the dynamics of proteolytic cleavage reactions and (ii) the analysis of proteolysis in complex biological samples that represent physiological conditions. PALeO-TimeCourse experiments help identifying rate-limiting processing

  3. Oxygen isotopes of Pacific seawater, 0-40 kyr, based on d18O and Mg/Ca of benthic and planktic foraminifera: relation to deglacial sealevel rise.

    NASA Astrophysics Data System (ADS)

    Mix, A. C.; Klinkhammer, G. P.

    2007-12-01

    Combining high resolution (~200 year sample resolution) oxygen and carbon isotope measurements and Mg/Ca analyses in planktic (G. ruber and N. dutertrei) and benthic foraminifera (Uvigerina sp.; use of infaunal benthics minimizes likely CO3= effects) from the mid-depth eastern Pacific provides for detailed estimates of changing d18O of seawater over the past 40 kyr at ODP Site 1242. The key to this analysis is improved precision of the Mg/Ca analyses based on a new generation of high precision flow-through time-resolved analysis (FT-TRA) (e.g., average internal precision for Mg/Ca is now +/-0.005 benthic, and +/-0.015 planktic). This method is relatively insensitive to mild dissolution of heterogeneous shells, and thus requires no corrections for preservation. The change in seawater d18O (at 1364 m depth) between the Holocene and Last Glacial Maximum is 1.2 +/- 0.04 permil when averaged over the stages, consistent with pore-water diffusion estimates; however, millennial scale events (which the pore-water data cannot detect) bring the total range up to about 1.6 permil. Are such short-term events related to sealevel change, or do they reflect changing watermasses? Measurements of d13C data (C. wuellerstorfi), sensitive to modern subsurface watermass gradients, are not highly correlated to short- term changes in d18Oseawater suggesting a transient response to ice volume changes. Glacial weakening of AAIW (salty, high d18O, high d13C) relative to north Pacific watermasses (fresher, lower d18O, low d13C) suggest that the benthic d18Oseawater may underestimate total local changes related to ice volume (with a caveat regarding proper scaling of benthic Mg/Ca to temperature). Benthic d18Oseawater falls through the deglaciation in steps, starting at 18 cal ka, with maximum rates of change at 14-15 ka, and with secondary rapid steps at 16-17 ka and 10-11 kar. Planktic foraminifera yield smaller glacial-interglacial d18Oseawater values, with Holocene-to-LGM stage- average

  4. Intra-shell d18O in Cultured Benthic Foraminiferan Amphistegina lobifera and the Influence of Seawater Carbonate Chemistry and Temperature on this Isotopic Composition

    NASA Astrophysics Data System (ADS)

    Rollion-Bard, C.; Erez, J.; Zilberman, T.; Segev, E.

    2006-12-01

    Using secondary ion mass spectrometry (SIMS) we looked at the natural variability in the oxygen isotope ratio of the shallow water, symbionts bearing foraminiferan A. lobifera. Live foraminifera were collected in June 2005 in the Gulf of Eilat, Israel. Vertical section exposing the knob area of this species represents the growth history of this species from December 2004 to June 2005. SIMS profile at a resolution of ~ 2 weeks yielded δ^1^8O changes of ~ 1.5 ‰, (from -0.1 ‰ to 1.45 ‰) that are compatible with the known temperature changes for the Gulf of Eilat for this period (20 to 25° C). Natural variability between primary and secondary calcite at the knob area were obtained on horizontal section of the upper knob area. The primary calcite is on average 2 ‰ more negative then the secondary calcite that represents the bulk of the skeleton (more then 95 % by weight). The δ^1^8O in the margin keel area of A. lobifera is also lower compared to the bulk secondary calcite. Specimens that were cultured in the laboratory at a constant temperature and inorganic carbon but at different pH have increased their CaCO3 weight by roughly a factor of 8. Single specimen from each pH (ranging between 7.9 and 8.5) was investigated with the SIMS at the knob area. While there is some variability within each specimen (perhaps related to the primary calcite), the general trend was a decrease in δ^1^8O with increasing pH (or CO32^- concentration), in agreement with previous studies on planktonic foraminifera. Specimens cultured in laboratory at a constant pH, but different temperature were also analysed in the knob area. The temperature range is between 21 and 33° C (experiments at 21, 24, 27 and 33° C). While there is also some variability within each specimen, the trend was a decrease in δ^1^8O with increasing temperature. The decrease measured is 2.7 ± 0.7 ‰ for the entire temperature range, which is completely in agreement with the theoretical value (-0.2 ‰ per

  5. Measurements of stable isotope ratios in milk samples from a farm placed in the mountains of Transylvania

    SciTech Connect

    Magdas, D. A. Cristea, G. Bot, A.; Puscas, R.; Radu, S.; Mirel, V.; Cordea, D. V.; Mihaiu, M.

    2013-11-13

    Product origin is of great importance for consumers especially because its association in consumer's perception with food quality, freedom from disease or pollution. Stable isotope ratio analysis is a powerful technique in food authenticity and traceability control which has been introduced within the European wine industry to ensure authenticity of wine provenance and to detect adulteration. Isotopic ratios measurements have also been successfully to other food commodities like: fruit juices, honey and dairy foods. The δ{sup 18}O and δ{sup 2}H content in milk water reflects the isotope composition of the ground water drunk by animals. Seasonal effects are also very important: in summer, milk water contains higher δ{sup 18}O and δ{sup 2}H values due to the fresh plants that are ate by animals. Relative carbon stable isotope abundances in total milk reflect the isotopic composition of the diet fed to the dairy cows. In this study the hydrogen, oxygen and carbon isotopic composition of 15 milk samples coming from a unit placed in the mountains of Transylvania was investigated. The distribution of the obtained isotopic values was than discussed taking into account that all the animals were feed with the same type of forage and consumed water was taken from the same source.

  6. Measurements of stable isotope ratios in milk samples from a farm placed in the mountains of Transylvania

    NASA Astrophysics Data System (ADS)

    Magdas, D. A.; Cristea, G.; Cordea, D. V.; Bot, A.; Puscas, R.; Radu, S.; Mirel, V.; Mihaiu, M.

    2013-11-01

    Product origin is of great importance for consumers especially because its association in consumer's perception with food quality, freedom from disease or pollution. Stable isotope ratio analysis is a powerful technique in food authenticity and traceability control which has been introduced within the European wine industry to ensure authenticity of wine provenance and to detect adulteration. Isotopic ratios measurements have also been successfully to other food commodities like: fruit juices, honey and dairy foods. The δ18O and δ2H content in milk water reflects the isotope composition of the ground water drunk by animals. Seasonal effects are also very important: in summer, milk water contains higher δ18O and δ2H values due to the fresh plants that are ate by animals. Relative carbon stable isotope abundances in total milk reflect the isotopic composition of the diet fed to the dairy cows. In this study the hydrogen, oxygen and carbon isotopic composition of 15 milk samples coming from a unit placed in the mountains of Transylvania was investigated. The distribution of the obtained isotopic values was than discussed taking into account that all the animals were feed with the same type of forage and consumed water was taken from the same source.

  7. Correcting Laser-Based Water Stable Isotope Readings Biased by Carrier Gas Changes.

    PubMed

    Gralher, Benjamin; Herbstritt, Barbara; Weiler, Markus; Wassenaar, Leonard I; Stumpp, Christine

    2016-07-01

    Recently, laser-based water stable isotope spectrometers have become popular as they enable previously impossible approaches of environmental observations. Consequently, they have been subjected to increasingly heterogeneous atmospheric conditions. However, there is still a severe lack of data on the impact of nonstandardized gas matrices on analyzer performances. Against this background, we investigated the influence of changing proportions of N2, O2, and CO2 in the carrier gas on the isotope measurements of a typical laser-based water stable isotope analyzer (Picarro L2120-i). We combined environmentally relevant mixtures of N2, O2, and CO2 with referenced, flash-evaporated water and found that isotope readings of the same water were altered by up to +14.57‰ for δ(18)O and -35.9‰ for δ(2)H. All tested relationships between carrier gas changes and respective isotope readings were strongly linearly correlated (R(2) > 0.99). Furthermore, an analyzer-measured variable allowed for reliable postcorrection of the biased isotope readings, which we additionally tested on field data. Our findings are of importance for environmental data obtained by analyzers based on the same technology. They are relevant for assays where inconsistent gas matrices or a mismatch in this regard between unknown and reference analyses cannot be excluded, which is in particular common when investigating the soil-vegetation-atmosphere continuum. PMID:27291718

  8. Coupling δ2H and δ18O biomarker results yields information on relative humidity and isotopic composition of precipitation - a climate transect validation study

    NASA Astrophysics Data System (ADS)

    Tuthorn, M.; Zech, R.; Ruppenthal, M.; Oelmann, Y.; Kahmen, A.; del Valle, H. F.; Eglinton, T.; Rozanski, K.; Zech, M.

    2015-06-01

    The hydrogen isotopic composition (δ2H) of leaf waxes, especially of n-alkanes (δ2Hn-alkanes), is increasingly used for paleohydrological and paleoclimate reconstructions. However, it is challenging to disentangle past changes in the isotopic composition of precipitation and changes in evapotranspirative enrichment of leaf water, which are both recorded in leaf wax δ2H values. In order to overcome this limitation, Zech M. et al. (2013) proposed a coupled δ2Hn-alkanes-δ18Osugar biomarker approach. This coupled approach allows for calculating (i) biomarker-based "reconstructed" δ2Hδ18O values of leaf water (δ2Hδ18Oleaf water), (ii) biomarker-based reconstructed deuterium excess (d-excess) of leaf water, which mainly reflects evapotranspirative enrichment and which can be used to reconstruct relative air humidity (RH) and (iii) biomarker-based reconstructed δ2Hδ18Oprecipitation values. Here we present a climate transect validation study by coupling new results from δ2H analyses of n-alkanes and fatty acids in topsoils along a climate transect in Argentina with previously measured δ18O results obtained for plant-derived sugars. Accordingly, both the reconstructed RH and δ2Hδ18Oprecipitation values correlate highly significantly with actual RH and δ2Hδ18Oprecipitation values. We conclude that compared to single δ2Hn-alkane or δ18Osugar records, the proposed coupled δ2Hn-alkane-δ18Osugar biomarker approach will allow more robust δ2Hδ18Oprecipitation reconstructions in future paleoclimate research. Additionally, the proposed coupled δ2Hn-alkane-δ18Osugar biomarker approach allows for the establishment of a "paleohygrometer", more specifically, the reconstruction of mean summer daytime RH changes/history.

  9. Stable isotope ratios of atmospheric CO_{2} and CH_{4} over Siberia measured at ZOTTO

    NASA Astrophysics Data System (ADS)

    Timokhina, Anastasiya; Prokushkin, Anatily; Lavric, Jost; Heimann, Martin

    2016-04-01

    The boreal and arctic zones of Siberia housing the large amounts of carbon stored in the living biomass of forests and wetlands, as well as in soils and specifically permafrost, play a crucial role in earth's global carbon cycle. The long-term studies of greenhouse gases (GHG) concentrations are important instruments to analyze the response of these systems to climate warming. In parallel to GHG observations, the measurements of their stable isotopic composition can provide useful information for distinguishing contribution of individual GHG source to their atmospheric variations, since each source has its own isotopic signature. In this study we report first results of laboratory analyses of the CO2 and CH4 concentrations, the stable isotope ratio of δ13C-CO2, δ18O-CO2, δ13C-CH4, δD-CH4 measured in one-liter glass flasks which were obtained from 301 height of ZOTTO (Zotino Tall Tower Observatory, near 60° N, 90° E, about 20 km west of the Yenisei River) during 2008 - 2013 and 2010 - 2013 for stable isotope composition of CO2 and CH4. The magnitudes of δ13C-CO2 and δ18O-CO2 in a seasonal cycle are -1.4±0.1‰ (-7.6 - -9.0‰) and -2.2±0.2‰ (-0.1 - -2.3‰), respectively. The δ13C-CO2 seasonal pattern opposes the CO2 concentrations, with a gradual enrichment in heavy isotope occurring during May - July, reflecting its discrimination in photosynthesis, and further depletion in August - September as photosynthetic activity decreases comparatively to ecosystem respiration. Relationship between the CO2 concentrations and respective δ13C-CO2 (Keeling plot) reveals isotopic source signature for growing season (May - September) -27.3±1.4‰ and -30.4±2.5‰ for winter (January - March). The behavior of δ18O-CO2 associated with both high photosynthetic rate in the June (enrichment of atmospheric CO2 by 18O as consequence of CO2 equilibrium with "heavy" leaf water) and respiratory activity of forest floor in June - October (depletion of respired CO2 by 18O

  10. Towards a Better Understanding of the Oxygen Isotope Signature of Atmospheric CO2: Determining the 18O-Exchange Between CO2 and H2O in Leaves and Soil On-line with Laser-Based Spectroscopy

    NASA Astrophysics Data System (ADS)

    Gangi, L.; Rothfuss, Y.; Vereecken, H.; Brueggemann, N.

    2013-12-01

    The oxygen isotope signature of carbon dioxide (δ18O-CO2) is a powerful tool to disentangle CO2 fluxes in terrestrial ecosystems, as CO2 attains a contrasting 18O signature by the interaction with isotopically different soil and leaf water pools during soil respiration and photosynthesis, respectively. However, using the δ18O-CO2 signal to quantify plant-soil-atmosphere CO2 fluxes is still challenging due to a lack of knowledge concerning the magnitude and effect of individual fractionation processes during CO2 and H2O diffusion and during CO2-H2O isotopic exchange in soils and leaves, especially related to short-term changes in environmental conditions (non-steady state). This study addresses this research gap by combined on-line monitoring of the oxygen isotopic signature of CO2 and water vapor during gas exchange in soil and plant leaves with laser-based spectroscopy, using soil columns and plant chambers. In both experimental setups, the measured δ18O of water vapor was used to infer the δ18O of liquid water, and, together with the δ18O-CO2, the degree of oxygen isotopic equilibrium between the two species (θ). Gas exchange experiments with different functional plant types (C3 coniferous, C3 monocotyledonous, C3 dicotyledonous, C4) revealed that θ and the influence of the plant on the ambient δ18O-CO2 (CO18O-isoforcing) not only varied on a diurnal timescale but also when plants were exposed to limited water availability, elevated air temperature, and abrupt changes in light intensity (sunflecks). Maximum θ before treatments ranged between 0.7 and 0.8 for the C3 dicotyledonous (poplar) and C3 monocotyledonous (wheat) plants, and between 0.5 and 0.6 for the conifer (spruce) and C4 plant (maize) while maximum CO18O-isoforcing was highest in wheat (0.03 m s-1 ‰), similar in poplar and maize (0.02 m s-1 ‰), and lowest in spruce (0.01 m s-1 ‰). Multiple regression analysis showed that up to 97 % of temporal dynamics in CO18O-isoforcing could be

  11. Using stable isotopes to determine the submarine groundwater discharge in the East China Sea

    NASA Astrophysics Data System (ADS)

    Lian, E.; Yang, S.; Yang, C.; Li, C.

    2013-12-01

    Over the last decade the flux of submarine groundwater discharge (SGD) to global ocean has been well investigated, which reaches 12, 000km3/yr, about 10~50% of the total riverine discharge into the ocean. The large uncertainty of the estimation of SGD flux lies in poor data in large river deltas and adjoining coastal areas. As a typical river-dominated epicontinental sea, the East China Sea is characterized by wide continental shelf and huge terrestrial input mostly from the Changjiang (Yangtze River). The Changjiang River exerts a significant role on sedimentological and biogeochemical processes in the East China Sea by delivering an enormous amount of dissolved and particulate materials. In this contribution, the riverwater and seawater samples were collected in dry and flood seasons in 2012 and 2013 for the measurements of stable H-O isotopes, with a major aim to examine the contribution of SGD off the Changjiang Estuary and on the coastal shelf. The results show that the values of δD and δ18O exhibit regular variations with seasons, controlled by the monsoon-induced rainfall and anthropogenic activities in the large Changjiang catchment. The δD and δ18O values in the groundwater samples from the boreholes in the Changjiang Delta fluctuate between -48.0 and -51.5‰ and between -5.9 and -7.55‰, respectively, while relatively positive values were observed in the seawater samples, ranging from -2.82 to 0.16‰ for δD and -0.54 to -0.26‰ for δ18O. Some of the offshore samples (about 50 km off the coast, 11-15 m below the sea surface) bear relatively negative isotopic values (δD: -11.21~ -3.25‰; δ18O: -1.55 ~ -0.23‰). The H-O isotopic compositions of these samples fall on a mixing line between those of groundwater and seawater samples, which probably reflects the SGD contribution. Based on the isotopic equilibrium calculation, it is estimated that about 18.7~23.1% of fresh groundwater resource flowing into the Changjiang estuarine and shelf areas is

  12. Assessing site-specific spatio-temporal variations in hydrogen and oxygen stable isotopes of human drinking water

    NASA Astrophysics Data System (ADS)

    Kennedy, C. D.; Bowen, G. J.; Ehleringer, J. R.

    2008-12-01

    Stable isotope ratios of hydrogen and oxygen (δ2H and δ18O) are environmental forensic tracers that can be used to constrain the origin and movement of animals, people, and products. The fundamental assumption underlying this method is that water resources at different geographic locations have distinct and characteristic isotopic signatures that are assimilated into organic tissues. Although much is known about regional-scale spatio-temporal variability in δ2H and δ18O of water, few studies have addressed the question of how distinct these geographic and seasonal patterns are for any given site. To address this question, a 2-year survey of δ2H and δ18O in tap water from across the contiguous U.S. and Canada was conducted. The data show that seasonal variability in δ2H and δ18O of tap water is generally low (<10 ‰ for δ2H), and those with the highest variability can be classified as: a) cities or towns in areas of high climate seasonality, or b) large cities in arid or seasonally arid regions which access and switch among multiple water sources throughout the year. The data suggest that inter-annual variation in tap water isotope ratios is typically low, with a median difference for month-month pairs during the 2 sampling years of 2.7 (δ2H). The results from this study confirm the existence of temporal variability in δ2H and δ18O of tap water, but suggest that this variability in human-managed systems is highly damped and may be amenable to classification, modeling, and prediction. In all, the data provide the foundation for incorporating temporal variation in predictive models of water and organic δ2H and δ18O, leading to more robust and statistically defensible tests of geographic origin.

  13. Stable isotope evolution and paleolimnology of ancient Lake Creede

    USGS Publications Warehouse

    Rye, Robert O.; Bethke, Philip M.; Finkelstein, David B.

    2000-01-01

    The lacustrine carbonate and travertine (tufa) deposits of ancient Lake Creede preserve a remarkable record of the isotopic evolution of the lake. That record indicates that the δ18O of the lake water, and by analogy its salinity, evolved through evaporation. Limited ans less reliable data on hydrous minerals and fluid inclusions in early diagenetic carbonates indicate that the δD of the lake waters also evolved through evaporation. The isotope data place restrictions on models of the physical limnology of the lake and its evolution. The closed-basin Lake Creede formed shortly after collapse of the 26.9 Ma Creede caldera. Throughout most of its history it occupied the northern three quarters of the moat between the resurgent dome and wall of the caldera. The Creede Formation was deposited in the basin, dominantly as lacustrine sediments. Travertine mounds interfinger with Creede Formation sediments along the inner and outer margins of the lake basin. An estimated one-half of the original thickness of the Creede Formation has been lost mainly to erosion although scattered remnants of the upper portion remain on the caldera walls. Two diamond core holes (CCM-1 and CCM-2) sampled the uneroded portion of the Creede Formation as part of the U.S. Continental Drilling Program. Volcaniclastic material, including tuff units deposited directly into the lake and ash washed in from the watershed, compose the main lithologies of the Creede Formation. These volcaniclastic strata were produced by episodic ring-fracture volcanism. Lacustrine carbonates make up about 15% of the section sampled by drill core. They occur as 1 mm to 2 cm low-Mg calcite laminar alternating with siliciclastic laminar in scattered intervals throughout the preserved section. The carbonate laminar are accumulations of 5-20 μm crystallites (microparites) and brine shrimmp fecal pellets (peloids) composed mainly of microparasite particles. Low-Mg calcite also occurs as an early diagenetic replacement of

  14. Altered Retinoic Acid Metabolism in Diabetic Mouse Kidney Identified by 18O Isotopic Labeling and 2D Mass Spectrometry

    PubMed Central

    Starkey, Jonathan M.; Zhao, Yingxin; Sadygov, Rovshan G.; Haidacher, Sigmund J.; LeJeune, Wanda S.; Dey, Nilay; Luxon, Bruce A.; Kane, Maureen A.; Napoli, Joseph L.; Denner, Larry; Tilton, Ronald G.

    2010-01-01

    Background Numerous metabolic pathways have been implicated in diabetes-induced renal injury, yet few studies have utilized unbiased systems biology approaches for mapping the interconnectivity of diabetes-dysregulated proteins that are involved. We utilized a global, quantitative, differential proteomic approach to identify a novel retinoic acid hub in renal cortical protein networks dysregulated by type 2 diabetes. Methodology/Principal Findings Total proteins were extracted from renal cortex of control and db/db mice at 20 weeks of age (after 12 weeks of hyperglycemia in the diabetic mice). Following trypsinization, 18O- and 16O-labeled control and diabetic peptides, respectively, were pooled and separated by two dimensional liquid chromatography (strong cation exchange creating 60 fractions further separated by nano-HPLC), followed by peptide identification and quantification using mass spectrometry. Proteomic analysis identified 53 proteins with fold change ≥1.5 and p≤0.05 after Benjamini-Hochberg adjustment (out of 1,806 proteins identified), including alcohol dehydrogenase (ADH) and retinaldehyde dehydrogenase (RALDH1/ALDH1A1). Ingenuity Pathway Analysis identified altered retinoic acid as a key signaling hub that was altered in the diabetic renal cortical proteome. Western blotting and real-time PCR confirmed diabetes-induced upregulation of RALDH1, which was localized by immunofluorescence predominantly to the proximal tubule in the diabetic renal cortex, while PCR confirmed the downregulation of ADH identified with mass spectrometry. Despite increased renal cortical tissue levels of retinol and RALDH1 in db/db versus control mice, all-trans-retinoic acid was significantly decreased in association with a significant decrease in PPARβ/δ mRNA. Conclusions/Significance Our results indicate that retinoic acid metabolism is significantly dysregulated in diabetic kidneys, and suggest that a shift in all-trans-retinoic acid metabolism is a novel feature in

  15. Late Quaternary palaeoenvironmental reconstruction from Lake Ohrid using stable isotopes

    NASA Astrophysics Data System (ADS)

    Lacey, Jack H.; Leng, Melanie J.; Francke, Alexander; Vogel, Hendrik; Zanchetta, Giovanni; Wagner, Bernd

    2016-04-01

    Lake Ohrid is a large, deep lake located on the Balkan Peninsula at the border between Macedonia and Albania, and is considered the oldest extant lake in Europe. An International Continental scientific Drilling Program (ICDP) deep drilling campaign was carried out in 2013 as part of the interdisciplinary Scientific Collaboration On Past Speciation Conditions in Lake Ohrid (SCOPSCO) project. Over 1500 m of sediment were recovered from six coring locations at the main target site in the central basin, where the maximum drill depth reached 569 m below the lake floor. Initial results indicate continuous lacustrine conditions over the past >1.2 Ma (Wagner et al., 2014). Here, we present oxygen and carbon isotope data (δ18O and δ13C) from carbonate from the upper 248 m of the SCOPSCO succession, which covers the last 640 ka, spanning marine isotope stages 15-1, according to an age model based on tephra and orbital tuning (Francke et al., 2015). Modern monitoring data show Lake Ohrid to be an evaporative system, where variations in δ18O of endogenic carbonate are primarily a function of changes in water balance, and δ13C largely reflects fluctuations in the amount of soil-derived CO2 and organic matter recycling. Our results indicate a trend from wetter to drier conditions through the Holocene, which is consistent with regional and hemispheric processes related to changes in insolation and progressive aridification. Over the last 640 ka, relatively stable climate conditions are inferred before ca. 450 ka, a transition to a wetter climate between ca. 400-250 ka, and a trend to drier climate after ca. 250 ka. Higher frequency, multi-millennial-scale oscillations observed during warm stages are most likely associated with regional climate change as a function of orbital forcing. This record is one of the most extensive and highly-resolved continental isotope records available, and emphasises the potential of Lake Ohrid as a valuable archive of long-term palaeoclimate and

  16. Stable Isotope Applications in Hydrologic Studies

    NASA Astrophysics Data System (ADS)

    Kendall, C.; Doctor, D. H.

    2003-12-01

    The topic of stream flow generation has received considerable attention over the last two decades, first in response to concern about "acid rain" and more recently in response to the increasingly serious contamination of surface and shallow groundwaters by anthropogenic contaminants. Many sensitive, low-alkalinity streams in North America and Europe are already acidified (see Chapter 9.10). Still more streams that are not yet chronically acidic may undergo acidic episodes in response to large rainstorms and/or spring snowmelt. These acidic events can seriously damage local ecosystems. Future climate changes may exacerbate the situation by affecting biogeochemical controls on the transport of water, nutrients, and other materials from land to freshwater ecosystems.New awareness of the potential danger to water supplies posed by the use of agricultural chemicals and urban industrial development has also focused attention on the nature of rainfall-runoff and recharge processes and the mobility of various solutes, especially nitrate and pesticides, in shallow systems. Dumping and spills of other potentially toxic materials are also of concern because these chemicals may eventually reach streams and other public water supplies. A better understanding of hydrologic flow paths and solute sources is required to determine the potential impact of contaminants on water supplies, develop management practices to preserve water quality, and devise remediation plans for sites that are already polluted.Isotope tracers have been extremely useful in providing new insights into hydrologic processes, because they integrate small-scale variability to give an effective indication of catchment-scale processes. The main purpose of this chapter is to provide an overview of recent research into the use of naturally occurring stable isotopes to track the movement of water and solutes in hydrological systems where the waters are relatively fresh: soils, surface waters, and shallow

  17. Uniform climate sensitivity in tree-ring stable isotopes across species and sites in a mid-latitude temperate forest.

    PubMed

    Hartl-Meier, Claudia; Zang, Christian; Büntgen, Ulf; Esper, Jan; Rothe, Andreas; Göttlein, Axel; Dirnböck, Thomas; Treydte, Kerstin

    2015-01-01

    Tree-ring stable isotopes, providing insight into drought-induced eco-physiological mechanisms, are frequently used to reconstruct past changes in growing season temperature and precipitation. Their climatic response is, however, still not fully understood, particularly for data originating from non-extreme, mid-latitude environments with differing ecological conditions. Here, we assess the response of δ(13)C, δ(18)O and tree-ring width (TRW) from a temperate mountain forest in the Austrian pre-Alps to climate and specific drought events. Variations in stem growth and isotopic composition of Norway spruce, common beech and European larch from dry, medium and moist sites are compared with records of sunshine, temperature, moisture, precipitation and cloud cover. Results indicate uniform year-to-year variations in δ(13)C and δ(18)O across sites and species, but distinct differences in TRW according to habitat and species. While the climate sensitivity of TRW is overall weak, the δ(13)C and δ(18)O chronologies contain significant signals with a maximum sensitivity to cloud cover changes (r = -0.72 for δ(18)O). The coherent inter-annual isotopic variations are accompanied by substantial differences in the isotopic signatures with offsets up to ∼3‰ for δ(13)C, indicating species-specific physiological strategies and varying water-use efficiencies. During severe summer drought, beech and larch benefit from access to deeper and moist soils, allowing them to keep their stomata open. This strategy is accompanied by an increased water loss through transpiration, but simultaneously enables enhanced photosynthesis. Our findings indicate the potential of tree-ring stable isotopes from temperate forests to reconstruct changes in cloud cover, and to improve knowledge on basic physiological mechanisms of tree species growing in different habitats to cope with soil moisture deficits.

  18. Uniform climate sensitivity in tree-ring stable isotopes across species and sites in a mid-latitude temperate forest

    NASA Astrophysics Data System (ADS)

    Hartl-Meier, Claudia; Zang, Christian; Büntgen, Ulf; Esper, Jan; Rothe, Andreas; Göttlein, Axel; Dirnböck, Thomas; Treydte, Kerstin

    2015-04-01

    Tree-ring stable isotopes, providing insight into drought-induced eco-physiological mechanisms, are frequently used to reconstruct past changes in growing season temperature and precipitation. Their climatic response is, however, still not fully understood, particularly for data originating from non-extreme, mid-latitude environments with differing ecological conditions. Here, we assess the response of δ13C, δ18O and tree-ring width (TRW) from a temperate mountain forest in the Austrian pre-Alps to climate and specific drought events. Variations in stem growth and isotopic composition of Norway spruce, common beech and European larch from dry, medium and moist sites are compared with records of sunshine, temperature, moisture, precipitation and cloud cover. Results indicate uniform year-to-year variations in δ13C and δ18O across sites and species, but distinct differences in TRW according to habitat and species. While the climate sensitivity of TRW is overall weak, the δ13C and δ18O chronologies contain significant signals with a maximum sensitivity to cloud cover changes (r = -0.72 for δ18O). The coherent inter-annual isotopic variations are accompanied by substantial differences in the isotopic signatures with offsets up to ˜3‰ for δ13C, indicating species-specific physiological strategies and varying water-use efficiencies. During severe summer drought, beech and larch benefit from access to deeper and moist soils, allowing them to keep their stomata open. This strategy is accompanied by an increased water loss through transpiration, but simultaneously enables enhanced photosynthesis. Our findings indicate the potential of tree-ring stable isotopes from temperate forests to reconstruct changes in cloud cover, and to improve knowledge on basic physiological mechanisms of tree species growing in different habitats to cope with soil moisture deficits.

  19. The effect of paleoecology and paleobiogeography on stable isotopes of Quaternary mammals from South America

    NASA Astrophysics Data System (ADS)

    Domingo, Laura; Prado, José Luis; Alberdi, María Teresa

    2012-11-01

    The modern South American mammalian assemblage was determined by the closure of the Panama isthmus (˜2.7-3.1 Ma) and later on, by profound climatic and environmental fluctuations occurred during the Quaternary as well as by the appearance of humans in the continent. In the present study, stable isotope analyses (δ13C, δO and δO) have been carried out on Pleistocene-Holocene northern inmigrant and endemic taxa from a broad latitudinal and altitudinal distribution in South America with the purpose of characterizing their paleoecology and the effects of the paleobiogeographic distribution on stable isotope results. Equids and gomphotheres show a wide range of δ13C values going from woodlands to pure C4 grasslands. In the case of equids, Hippidion shows lower δ13C values than Equus in the Late Pleistocene, whereas, in the case of gomphotheres, Cuvieronius and Stegomastodon differ in their δ18O values on account on differences in their paleobiogeography with the former found in the Andean corridor and the latter dispersing through an eastern route. Isotope data of the rest of taxa (immigrant and endemic) are in general in good agreement with other previous isotopic and non-isotopic studies. The latitude threshold between mixed C3-C4 and pure C3 conditions have been pinpointed at ˜33°S in the Middle and the Late Pleistocene. Mammalian δ18O values are intimately related to latitudinal and altitudinal distribution, with the latter exerting an overriding influence independently of latitude. Calculated altitudinal gradients (between -0.23‰/100 m and -0.40‰/100 m) are within the range of modern gradients.

  20. INCORPORATING CONCENTRATION DEPENDENCE IN STABLE ISOTOPE MIXING MODELS

    EPA Science Inventory

    Stable isotopes are frequently used to quantify the contributions of multiple sources to a mixture; e.g., C and N isotopic signatures can be used to determine the fraction of three food sources in a consumer's diet. The standard dual isotope, three source linear mixing model ass...

  1. INCORPORATING CONCENTRATION DEPENDENCE IN STABLE ISOTOPE MIXING MODELS

    EPA Science Inventory

    Stable isotopes are often used as natural labels to quantify the contributions of multiple sources to a mixture. For example, C and N isotopic signatures can be used to determine the fraction of three food sources in a consumer's diet. The standard dual isotope, three source li...

  2. Retrograde fluids in granulites: Stable isotope evidence of fluid migration

    SciTech Connect

    Morrison, J. ); Valley, J.W. )

    1991-07-01

    Widespread retrograde alteration assemblages document the migration of mixed H{sub 2}O-CO{sub 2} fluids into granulite facies rocks in the Adirondack Mountains. Fluid migration is manifest by (1) veins and patchy intergrowths of chlorite {plus minus} sericite {plus minus} calcite, (2) small veins of calcite, many only identifiable by cathodoluminescence, and (3) high-density, CO{sub 2}-rich or mixed H{sub 2}O-CO{sub 2} fluid inclusions. The distinct and varied textural occurrences of the alteration minerals indicate that fluid-rock ratios were low and variable on a local scale. Stable isotope ratios of C, O, and S have been determined in retrograde minerals from samples of the Marcy anorthosite massif and adjacent granitic gneisses (charnockites). Retrograde calcite in the anorthosite has a relatively small range in both {delta}{sup 18}O{sub SMOW} and {delta}{sup 13}C{sub PDB} (8.6 to 14.9% and {minus}4.1 to 0.4%, respectively), probably indicating that the hydrothermal fluids that precipitated the calcite had exchanged with a variety of crustal lithologies including marbles and orthogneisses, and that calcite was precipitated over a relatively narrow temperature interval. Values of {delta}{sup 34}S{sub CDT} that range from 2.8 to 8.3% within the anorthosite can also be interpreted to reflect exchange between orthogneisses and metasediments. The recognition of retrograde fluid migration is particularly significant in granulite facies terranes because the controversy surrounding the origin of granulites arises in part from differing interpretations of fluid inclusion data, specifically, the timing of entrapment of high-density, CO{sub 2}-rich inclusions. Results indicate that retrograde fluid migration, which in some samples may leave only cryptic petrographic evidence, is a process capable of producing high-density, CO{sub 2}-rich fluid inclusions.

  3. The genesis of emeralds and their host rocks from Swat, northwestern Pakistan: a stable-isotope investigation

    NASA Astrophysics Data System (ADS)

    Arif, M.; Fallick, A. E.; Moon, C. J.

    1996-05-01

    Emerald deposits in Swat, northwestern Pakistan, occurring in talc-magnesite and quartz-magnesite assemblages, have been investigated through stable isotope studies. Isotopic analyses were performed on a total of seven emeralds, associated quartz (seven samples), fuchsite (three samples) and tourmaline (two samples) from the Mingora emerald mines. The oxygen isotopic composition (δ18O SMOW) of emeralds shows a strong enrichment in 18O and is remarkably uniform at +15.6±0.4‰ (1σ, n=7). Each of the two components of water in emerald (channel and inclusion) has a different range of hydrogen isotopic composition: the channel waters being distinctly isotopically heavier (δD=-51 to -32‰ SMOW) than the other inclusion waters (δD=-96 to -70‰ SMOW). Similarly the oxygen isotopic compositions of tourmaline and fuchsite are relatively constant (δ18O=+13 to +14‰ SMOW) and show enrichment in 18O. The δ18O values of quartz, ranging from +15.1 to +19.1‰ SMOW, are also high (+16.9±1.4‰; 1σ, n=7). The mean δD of channel waters measured from emerald (-42±6.6‰ SMOW) and that of fluid calculated from hydrous minerals δDcalculated (-47±7.1‰ SMOW) are consistent with both metamorphic and magmatic origin. However, the close similarity between the measured δD values of the hydroxyl hydrogen in fuchsite (-74 to -61‰ SMOW) and tourmaline (-84 and -69‰ SMOW) with pegmatitic muscovite and tourmaline suggests that the mineralization was probably caused by modified (18O-enriched) hydrothermal solutions derived from an S-type granitic magma. The variation in the carbon and oxygen isotopic composition of magnesite, locally associated with emerald mineralization, is also very restricted (δ13C˜-3.2±0.7‰ PDB; δ18O˜ +17.9±1.2‰ SMOW). On the basis of the isotopic composition of fluid (δ13C≈-1.8±0.7‰ PDB; δ18O≈+13.6±1.2‰ SMOW calculated for the 250 550 °C temperature), it is proposed that the Swat magnesites formed due to the carbonation of

  4. Use of stable isotope analysis in determining aquatic food webs

    EPA Science Inventory

    Stable isotope analysis is a useful tool for describing resource-consumer dynamics in ecosystems. In general, organisms of a given trophic level or functional feeding group will have a stable isotope ratio identifiable different than their prey because of preferential use of one ...

  5. Stable isotope customer list and summary of shipments - FY 1981

    SciTech Connect

    Davis, W.C.

    1982-05-01

    This compilation is published as an aid to those concerned with the separation and sale of stable isotopes. The information is divided into four sections: alphabetical list of domestic and foreign customers, showing the stable isotopes purchased during the fiscal year; alphabetical list of isotopes, cross-referenced to customer numbers and divided into domestic and foreign categories; alphabetical list of states and countries, cross-referenced to customer numbers and divided into domestic and foreign categories; alphabetical list of states and countries, cross-referenced to customer numbers and indicating geographical concentrations of isotope users; and tabulation of the shipments, quantities, and dollars for domestic, foreign, and project categories for each isotope.

  6. Stable isotope customer list and summary of shipments - FY 1983

    SciTech Connect

    Davis, W.C.

    1983-12-01

    This compilation is published as an aid to those concerned with the separation and sale of stable isotopes. The information is divided into four sections: (1) alphabetical list of domestic and foreign customers, showing the stable isotopes purchased during the fiscal year; (2) alphabetical list of isotopes, cross-referenced to customer numbers and divided into domestic and foreign categories; (3) alphabetical list of states and countries, cross-referenced to customer numbers and indicating geographical concentrations of isotope users; and (4) tabulation of the shipments, quantities, and dollars for domestic, foreign, and project categories for each isotope.

  7. Mechanisms of subglacial groundwater recharge as derived from noble gas, 14C, and stable isotopic data

    NASA Astrophysics Data System (ADS)

    Grundl, Tim; Magnusson, Nathan; Brennwald, Matthias S.; Kipfer, Rolf

    2013-05-01

    Noble gas, stable isotope and 14C data from samples collected along groundwater flow path within a confined Paleozoic aquifer in northeastern Wisconsin, USA are used to deduce the effect of the Laurentide Ice Sheet (LIS) on the underlying groundwater and its recharge dynamics. During the last glacial maximum the investigated area was near the center of the Green Bay Lobe of the LIS. 14C ages that extend to 26 k.a. and low δ18O derived temperatures during the time that the LIS was present indicate that aquifer recharge continued when ice covered the area. δ18O values as low as -17.5‰ and δ2H values as low as -127.7‰ indicate that a significant portion of aquifer recharge was derived from glacial meltwater that maintained its glacial isotopic signature during melting and subsequent recharge. Noble gas temperatures that remain above freezing at a constant ~3 °C, unusually high excess air (ΔNe) values and noble gas fractionation patterns indicate that recharge occurred across a very dynamic water table located within the ice sheet. This englacial hydrologic system experienced recharge heads of as much as 7.8 m. Evidence for direct recharge of basal meltwater into the aquifer is not seen. To the authors' knowledge this is the first time that noble gas and isotope tracers have been used to deduce the provenance of aquifer water beneath continental ice sheets.

  8. Identification of sources and production processes of bottled waters by stable hydrogen and oxygen isotope ratios.

    PubMed

    Brencic, Mihael; Vreca, Polona

    2006-01-01

    Bottled water is a food product that considerably depends on the environment from which it originates, not only at the place where it is produced, but predominantly on the conditions in the recharge area of the wells captured for bottling. According to their source and the bottling process, bottled waters can be divided into natural and artificially sparkling waters, still and flavoured waters. These waters originate from various parts of the hydrological cycle and their natural origin is reflected in their hydrogen and oxygen stable isotopic compositions (delta(2)H and delta(18)O). A total of 58 domestic and foreign brands and 16 replicates of bottled waters, randomly collected on the Slovene market in September 2004, were analysed for delta(2)H and delta(18)O. The isotopic composition varied between -83 per thousand and -46 per thousand with an average of -66 per thousand for hydrogen, and between -11.9 per thousand and -7.5 per thousand with an average of -9.6 per thousand for oxygen. This investigation helped (1) to determine and test the classification of bottled waters, (2) to determine the natural origin of bottled water, and (3) to indicate differences between the natural and production processes. The production process may influence the isotopic composition of flavoured waters and artificially sparkling waters. No such modification was observed for still and natural sparkling waters. The methods applied, together with hydrological knowledge, can be used for the authentication of bottled waters for regulatory and consumer control applications.

  9. The use of stable isotope to evaluate water mixing and water use by flood plain trees along the Garonne valley

    USGS Publications Warehouse

    Lambs, L.; Loubiat, M.; Richardson, W.

    2003-01-01

    Before the confluence of the Tarn, the Garonne valley was the driest area in the entire south-west of France, due to the relatively low rainfall and low summer discharge of the Garonne River and its tributaries. The natural abundance of the stable isotope of oxygen (18O) and ionic charge of surface and ground water were used to estimate the water source for the Garonne River and phreatic subsurface water. We also measured these constituents in the sap of trees at several flood plain sites to better understand the source of water used by these trees. 18O signatures and conductivity in the Garonne River indicated that the predominance of water was from high altitude surface runoff from the Pyrenees Mountains. Tributary inputs had little effect on isotopic identity, but had a small effect on the conductivity. The isotopic signature and ionic conductivity of river water (??18O: -9.1??? to -9.0???, conductivity: 217-410??S/cm) was distinctly different from groundwater (??18O: -7.1??? to -6.6???, conductivity: 600-900??S/cm). Isotopic signatures from the sap of trees on the flood plain showed that the water source was shallow subsurface water (1m). Trees at both locations maintained sap with ionic charges much greater (2.3-3.7x) than that of source water. The combined use of 18O signatures and ionic conductivity appears to be a potent tool to determine water sources on geographic scales, and source and use patterns by trees at the local forest scale. These analyses also show promise for better understanding of the effects of anthropogenic land-use and water-use changes on flood plain forest dynamics.

  10. The use of stable isotopes to evaluate water mixing and water use by flood plain trees along the Garonne valley.

    PubMed

    Lambs, L; Loubiat, M; Richardson, W

    2003-12-01

    Before the confluence of the Tarn, the Garonne valley was the driest area in the entire south-west of France, due to the relatively low rainfall and low summer discharge of the Garonne River and its tributaries. The natural abundance of the stable isotope of oxygen (18O) and ionic charge of surface and ground water were used to estimate the water source for the Garonne River and phreatic subsurface water. We also measured these constituents in the sap of trees at several flood plain sites to better understand the source of water used by these trees. 18O signatures and conductivity in the Garonne River indicated that the predominance of water was from high altitude surface runoff from the Pyrenees Mountains. Tributary inputs had little effect on isotopic identity, but had a small effect on the conductivity. The isotopic signature and ionic conductivity of river water (delta18O: -9.1 per thousand to -9.0 per thousand, conductivity: 217-410 microS/cm) was distinctly different from groundwater (delta18O: -7.1 per thousand to -6.6 per thousand, conductivity: 600-900 microS/cm). Isotopic signatures from the sap of trees on the flood plain showed that the water source was shallow subsurface water (<30 cm), whereas trees further from the river relied on deeper ground water (>1 m). Trees at both locations maintained sap with ionic charges much greater (2.3-3.7x) than that of source water. The combined use of 18O signatures and ionic conductivity appears to be a potent tool to determine water sources on geographic scales, and source and use patterns by trees at the local forest scale. These analyses also show promise for better understanding of the effects of anthropogenic land-use and water-use changes on flood plain forest dynamics.

  11. Stable water isotope simulation by current land-surface schemes:Results of IPILPS phase 1

    SciTech Connect

    Henderson-Sellers, A.; Fischer, M.; Aleinov, I.; McGuffie, K.; Riley, W.J.; Schmidt, G.A.; Sturm, K.; Yoshimura, K.; Irannejad, P.

    2005-10-31

    Phase 1 of isotopes in the Project for Intercomparison of Land-surface Parameterization Schemes (iPILPS) compares the simulation of two stable water isotopologues ({sup 1}H{sub 2} {sup 18}O and {sup 1}H{sup 2}H{sup 16}O) at the land-atmosphere interface. The simulations are off-line, with forcing from an isotopically enabled regional model for three locations selected to offer contrasting climates and ecotypes: an evergreen tropical forest, a sclerophyll eucalypt forest and a mixed deciduous wood. Here we report on the experimental framework, the quality control undertaken on the simulation results and the method of intercomparisons employed. The small number of available isotopically-enabled land-surface schemes (ILSSs) limits the drawing of strong conclusions but, despite this, there is shown to be benefit in undertaking this type of isotopic intercomparison. Although validation of isotopic simulations at the land surface must await more, and much more complete, observational campaigns, we find that the empirically-based Craig-Gordon parameterization (of isotopic fractionation during evaporation) gives adequately realistic isotopic simulations when incorporated in a wide range of land-surface codes. By introducing two new tools for understanding isotopic variability from the land surface, the Isotope Transfer Function and the iPILPS plot, we show that different hydrological parameterizations cause very different isotopic responses. We show that ILSS-simulated isotopic equilibrium is independent of the total water and energy budget (with respect to both equilibration time and state), but interestingly the partitioning of available energy and water is a function of the models' complexity.

  12. Using Water Vapor Isotope Observations from above the Greenland Ice Sheet to improve the Interpretation of Ice Core Water Stable Isotope Records

    NASA Astrophysics Data System (ADS)

    Steen-Larsen, H. C.; Masson-Delmotte, V.; Risi, C. M.; Yoshimura, K.; Werner, M.; Butzin, M.; Brun, E.; Landais, A.; Bonne, J. L.; Dahl-Jensen, D.

    2014-12-01

    Water stable isotope data from Greenland ice cores provide key paleoclimatic information. For the purpose of improving the climatic interpretation from ice core records, a monitoring of the isotopic composition δ18O and δD at several height levels (up to 13 meter) of near-surface water vapor, precipitation and snow in the first 0.5 cm surface layer has been conducted during three summers (2010-2012) at NEEM, NW Greenland. We compare the observed water vapor isotopic composition with model outputs from three isotope-enabled general circulation models: LMDZiso, isoGSM, ECHAM-wiso. This allows us to benchmark the models and address effect of model resolution, effect of transport, effect of isotope parameterization, and representation of significant source region contributions. We find for all models that the simulated isotopic value δD are significantly biased towards too enriched values. A bias, which is only partly explained by the air temperature. The simulated amplitude in d-excess variations is ~50% smaller than observed and the simulated average summer level is ~10‰ lower than in observations. Using back trajectories we observe water vapor of Arctic origin to have a high d-excess fingerprint. This fingerprint is not observed in the GCMiso simulations indicating a problem of simulating accurately the Arctic hydrological cycle. The bias in the simulated δD and d-excess water vapor is similar to the already-documented bias in the simulated δD and d-excess of Greenland ice core records. This suggests that if we improve the simulation of the water vapor isotopic composition we might also improve the simulation of the ice core isotope record. During periods between precipitation events, our data demonstrate parallel changes of δ18O and d-excess in surface snow and near-surface vapor. The changes in δ18O of the vapor are similar or larger than those of the snow δ18O. It is estimated using the CROCUS snow model that 6 to 20% of the surface snow mass is

  13. Recorders of reef environment histories: stable isotopes in corals, giant clams, and calcareous algae

    NASA Astrophysics Data System (ADS)

    Aharon, Paul

    1991-06-01

    Time-series δ18O and δ13C records from cohabiting massive coral Porites australiensis and giant clam Tridacna gigas from the Great Barrier Reed of Australia, and from calcareous green algae in a core through modern Halimeda bioherm accreting in the eastern Java Sea, provide insights into the complex links between environmental factors and stable isotopes imprinted in these reef skeletal materials. The aragonitic coral and giant clam offer 20 years and 15 years of growth history, respectively. The giant clam yields mean δ18O and δ13C values of-0.5±0.5‰ and 2.2±0.2‰ ( n=67), which agree well with the predicted equilibrium values. The coral yields mean δ18O and δ13C values of-5.6±0.5‰ and-1.8±0.7‰ ( n=84), offering a striking example of kinetic and metabolic fractionation effects. Although both the coral and giant clam harbor symbionts and were exposed to a uniform ambient environment during their growth histories, their distinct isotopic compositions demonstrate dissimilar calcification pathways. The δ18O records contain periodicities corresponding to the alternating annual density bands revealed by X-radiography and optical transmitted light. Attenuation of the δ18O seasonal amplitudes occurring in the giant clam record 8 years after skeletal growth commenced is attributed to a changeover from fast to slow growth rates. Extreme seasonal δ18O amplitudes of up to 2.2‰ discerned in both the coral and giant clam records exceed the equivalent seasonal temperature contrast in the reef environment, and are caused by the combined effect of rainfall and evaporation during the monsoon and dry seasons, respectively. Thus in addition of being useful temperature recorders, reef skeletal material of sufficient longevity, such as Porites and Tridacna, may also indicate rainfall variations. Changing growth rates, determined from the annual growth bands, may exert a primary control on the coral δ13C record which shows a remarkable negative shift of 1.7

  14. Stable isotopic evidence for anaerobic maintained sulphate discharge in a polythermal glacier

    NASA Astrophysics Data System (ADS)

    Ansari, A. H.

    2016-03-01

    To understand the sources and sinks of sulphate and associated biogeochemical processes in a High Arctic environment, late winter snowpacks, the summer melt-waters and rock samples were collected and analysed for major ions and stable isotope tracers (δ18O, δ34S). The SO42bar/Clbar ratio reveal that more than 87% of sulphate (frequently > 95%) of total sulphate carried by the subglacial runoff and proglacial streams was derived from non-snowpack sources. The proximity of non-snowpack sulphate δ34S (∼8-19‰) to the δ34S of the major rocks in the vicinity (∼-6 to +18‰) suggest that the non-snowpack sulphate was principally derived from rock weathering. Furthermore, Ca2++Mg2+/SO42ˉ molar shows that sulphate acquisition in the meltwaters was controlled by two major processes: 1) coupled-sulphide carbonate weathering (molar ratio ∼ 2) and, 2) re-dissolution of secondary salts (molar ratio ∼ 1). The δ34S-SO4 = +19.4‰ > δ34S-S of rock, accompanied by increased sulphate concentration also indicates an input from re-dissolution of secondary salts. Overall, δ18O composition of these non-snowpack sulphate (-11.9 to -2.2‰) mostly stayed below the threshold δ18O value (-6.7 to -3.3‰) for minimum O2 condition, suggesting that certain proportion of sulphate was regularly supplied from anaerobic sulphide oxidation.

  15. Stable isotopes of water in estimation of groundwater dependence in peatlands

    NASA Astrophysics Data System (ADS)

    Isokangas, Elina; Rossi, Pekka; Ronkanen, Anna-Kaisa; Marttila, Hannu; Rozanski, Kazimierz; Kløve, Bjørn

    2016-04-01

    Peatland hydrology and ecology can be irreversibly affected by anthropogenic actions or climate change. Especially sensitive are groundwater dependent areas which are difficult to determine. Environmental tracers such as stable isotopes of water are efficient tools to identify these dependent areas and study water flow patterns in peatlands. In this study the groundwater dependence of a Finnish peatland complex situated next to an esker aquifer was studied. Groundwater seepage areas in the peatland were localized by thermal imaging and the subsoil structure was determined using ground penetrating radar. Water samples were collected for stable isotopes of water (δ18O and δ2H), temperature, pH and electrical conductivity at 133 locations of the studied peatland (depth of 10 cm) at approximately 100 m intervals during 4 August - 11 August 2014. In addition, 10 vertical profiles were sampled (10, 30, 60 and 90 cm depth) for the same parameters and for hydraulic conductivity. The cavity ring-down spectroscopy (CRDS) was applied to measure δ18O and δ2H values. The local meteoric water line was determined using precipitation samples from Nuoritta station located 17 km west of the study area and the local evaporation line was defined using water samples from lake Sarvilampi situated on the studied peatland complex. Both near-surface spatial survey and depth profiles of peatland water revealed very wide range in stable isotope composition, from approximately -13.0 to -6.0 ‰ for δ18O and from -94 to -49 ‰ for δ2H, pointing to spatially varying influence of groundwater input from near-by esker aquifer. In addition, position of the data points with respect to the local meteoric water line showed spatially varying degree of evaporation of peatland water. Stable isotope signatures of peatland water in combination with thermal images delineated the specific groundwater dependent areas. By combining the information gained from different types of observations, the

  16. Present limitations and future prospects of stable isotope methods for nitrate source identification in surface- and groundwater.

    PubMed

    Xue, Dongmei; Botte, Jorin; De Baets, Bernard; Accoe, Frederik; Nestler, Angelika; Taylor, Philip; Van Cleemput, Oswald; Berglund, Michael; Boeckx, Pascal

    2009-03-01

    Nitrate (NO3(-)) contamination of surface- and groundwater is an environmental problem in many regions of the world with intensive agriculture and high population densities. Knowledge of the sources of NO3(-) contamination in water is important for better management of water quality. Stable nitrogen (delta15N) and oxygen (delta18O) isotope data of NO3(-) have been frequently used to identify NO3(-) sources in water. This review summarizes typical delta15N- and delta18O-NO3(-) ranges of known NO3(-) sources, interprets constraints and future outlooks to quantify NO3(-) sources, and describes three analytical techniques ("ion-exchange method", "bacterial denitrification method", and "cadmium reduction method") for delta15N- and delta18)O-NO3(-) determination. Isotopic data can provide evidence for the presence of dominant NO3(-) sources. However, quantification, including uncertainty assessment, is lacking when multiple NO3(-) sources are present. Moreover, fractionation processes are often ignored, but may largely constrain the accuracy of NO3(-) source identification. These problems can be overcome if (1) NO3(-) isotopic data are combined with co-migrating discriminators of NO3(-) sources (e.g. (11)B), which are not affected by transformation processes, (2) contributions of different NO3(-) sources can be quantified via linear mixing models (e.g. SIAR), and (3) precise, accurate and high throughput isotope analytical techniques become available.

  17. Fractionation of Oxygen Isotopes by Thermal Ionization Mass Spectrometry Inferred from Simultaneous Measurement of (17)O/(16)O and (18)O/(16)O Ratios and Implications for the (182)Hf-(182)W Systematics.

    PubMed

    Trinquier, Anne

    2016-06-01

    Accurate (182)Hf-(182)W chronology of early planetary differentiation relies on highly precise and accurate tungsten isotope measurements. WO3(-) analysis by negative thermal ionization mass spectrometry requires W(17)O(16)O2(-), W(17)O2(16)O(-), W(18)O(16)O2(-), W(17)O3(-), W(17)O(18)O(16)O(-), and W(18)O2(16)O(-) isotopologue interference corrections on W(16)O3(-) species ( Harper et al. Geochim. Cosmochim. Acta 1996 , 60 , 1131 ; Quitté et al. Geostandard. Newslett. 2002 , 26 , 149 ; Trinquier et al. Anal. Chem. 2016 , 88 , 1542 ; Touboul et al. Nature 2015 , 520 , 530 ; Touboul et al. Int. J. Mass Spectrom. 2012 , 309 , 109 ). In addition, low ion beam intensity counting statistics combined with Faraday cup detection noise limit the precision on the determination of (18)O/(16)O and (17)O/(16)O relative abundances. Mass dependent variability of (18)O/(16)O over the course of an analysis and between different analyses calls for oxide interference correction on a per integration basis, based on the in-run monitoring of the (18)O/(16)O ratio ( Harper et al. Geochim. Cosmochim. Acta 1996 , 60 , 1131 ; Quitté et al. Geostandard. Newslett. 2002 , 26 , 149 ; Trinquier et al. Anal. Chem. 2016 , 88 , 1542 ). Yet, the (17)O/(16)O variation is normally not being monitored and, instead, inferred from the measured (18)O/(16)O variation, assuming a δ(17)O-δ(18)O Terrestrial Fractionation Line ( Trinquier et al. Anal. Chem. 2016 , 88 , 1542 ). The purpose of the present study is to verify the validity of this assumption. Using high resistivity amplifiers, (238)U(17)O2 and (238)U(18)O2 ion beams down to 1.6 fA have been monitored simultaneously with (235,238)U(16)O2 species in a uranium certified reference material. This leads to a characterization of O isotope fractionation by thermal ionization mass spectrometry in variable loading and running conditions (additive-to-sample ratio, PO2 pressure, presence of ionized metal and oxide species). Proper determination of O

  18. Fractionation of Oxygen Isotopes by Thermal Ionization Mass Spectrometry Inferred from Simultaneous Measurement of (17)O/(16)O and (18)O/(16)O Ratios and Implications for the (182)Hf-(182)W Systematics.

    PubMed

    Trinquier, Anne

    2016-06-01

    Accurate (182)Hf-(182)W chronology of early planetary differentiation relies on highly precise and accurate tungsten isotope measurements. WO3(-) analysis by negative thermal ionization mass spectrometry requires W(17)O(16)O2(-), W(17)O2(16)O(-), W(18)O(16)O2(-), W(17)O3(-), W(17)O(18)O(16)O(-), and W(18)O2(16)O(-) isotopologue interference corrections on W(16)O3(-) species ( Harper et al. Geochim. Cosmochim. Acta 1996 , 60 , 1131 ; Quitté et al. Geostandard. Newslett. 2002 , 26 , 149 ; Trinquier et al. Anal. Chem. 2016 , 88 , 1542 ; Touboul et al. Nature 2015 , 520 , 530 ; Touboul et al. Int. J. Mass Spectrom. 2012 , 309 , 109 ). In addition, low ion beam intensity counting statistics combined with Faraday cup detection noise limit the precision on the determination of (18)O/(16)O and (17)O/(16)O relative abundances. Mass dependent variability of (18)O/(16)O over the course of an analysis and between different analyses calls for oxide interference correction on a per integration basis, based on the in-run monitoring of the (18)O/(16)O ratio ( Harper et al. Geochim. Cosmochim. Acta 1996 , 60 , 1131 ; Quitté et al. Geostandard. Newslett. 2002 , 26 , 149 ; Trinquier et al. Anal. Chem. 2016 , 88 , 1542 ). Yet, the (17)O/(16)O variation is normally not being monitored and, instead, inferred from the measured (18)O/(16)O variation, assuming a δ(17)O-δ(18)O Terrestrial Fractionation Line ( Trinquier et al. Anal. Chem. 2016 , 88 , 1542 ). The purpose of the present study is to verify the validity of this assumption. Using high resistivity amplifiers, (238)U(17)O2 and (238)U(18)O2 ion beams down to 1.6 fA have been monitored simultaneously with (235,238)U(16)O2 species in a uranium certified reference material. This leads to a characterization of O isotope fractionation by thermal ionization mass spectrometry in variable loading and running conditions (additive-to-sample ratio, PO2 pressure, presence of ionized metal and oxide species). Proper determination of O

  19. Spectral analysis software improves confidence in plant and soil water stable isotope analyses performed by isotope ratio infrared spectroscopy (IRIS).

    PubMed

    West, A G; Goldsmith, G R; Matimati, I; Dawson, T E

    2011-08-30

    Previous studies have demonstrated the potential for large errors to occur when analyzing waters containing organic contaminants using isotope ratio infrared spectroscopy (IRIS). In an attempt to address this problem, IRIS manufacturers now provide post-processing spectral analysis software capable of identifying samples with the types of spectral interference that compromises their stable isotope analysis. Here we report two independent tests of this post-processing spectral analysis software on two IRIS systems, OA-ICOS (Los Gatos Research Inc.) and WS-CRDS (Picarro Inc.). Following a similar methodology to a previous study, we cryogenically extracted plant leaf water and soil water and measured the δ(2)H and δ(18)O values of identical samples by isotope ratio mass spectrometry (IRMS) and IRIS. As an additional test, we analyzed plant stem waters and tap waters by IRMS and IRIS in an independent laboratory. For all tests we assumed that the IRMS value represented the "true" value against which we could compare the stable isotope results from the IRIS methods. Samples showing significant deviations from the IRMS value (>2σ) were considered to be contaminated and representative of spectral interference in the IRIS measurement. Over the two studies, 83% of plant species were considered contaminated on OA-ICOS and 58% on WS-CRDS. Post-analysis, spectra were analyzed using the manufacturer's spectral analysis software, in order to see if the software correctly identified contaminated samples. In our tests the software performed well, identifying all the samples with major errors. However, some false negatives indicate that user evaluation and testing of the software are necessary. Repeat sampling of plants showed considerable variation in the discrepancies between IRIS and IRMS. As such, we recommend that spectral analysis of IRIS data must be incorporated into standard post-processing routines. Furthermore, we suggest that the results from spectral analysis be

  20. Stable isotope views on ecosystem function: challenging or challenged?

    PubMed Central

    Resco, Víctor; Querejeta, José I.; Ogle, Kiona; Voltas, Jordi; Sebastià, Maria-Teresa; Serrano-Ortiz, Penélope; Linares, Juan C.; Moreno-Gutiérrez, Cristina; Herrero, Asier; Carreira, José A.; Torres-Cañabate, Patricia; Valladares, Fernando

    2010-01-01

    Stable isotopes and their potential for detecting various and complex ecosystem processes are attracting an increasing number of scientists. Progress is challenging, particularly under global change scenarios, but some established views have been challenged. The IX meeting of the Spanish Association of Terrestrial Ecology (AAET, Úbeda, 18–22 October 2009) hosted a symposium on the ecology of stable isotopes where the linear mixing model approach of partitioning sinks and sources of carbon and water fluxes within an ecosystem was challenged, and new applications of stable isotopes for the study of plant interactions were evaluated. Discussion was also centred on the need for networks that monitor ecological processes using stable isotopes and key ideas for fostering future research with isotopes. PMID:20015858

  1. Three-year monitoring of stable isotopes of precipitation at Concordia Station, East Antarctica

    NASA Astrophysics Data System (ADS)

    Stenni, Barbara; Scarchilli, Claudio; Masson-Delmotte, Valerie; Schlosser, Elisabeth; Ciardini, Virginia; Dreossi, Giuliano; Grigioni, Paolo; Bonazza, Mattia; Cagnati, Anselmo; Karlicek, Daniele; Risi, Camille; Udisti, Roberto; Valt, Mauro

    2016-10-01

    Past temperature reconstructions from Antarctic ice cores require a good quantification and understanding of the relationship between snow isotopic composition and 2 m air or inversion (condensation) temperature. Here, we focus on the French-Italian Concordia Station, central East Antarctic plateau, where the European Project for Ice Coring in Antarctica (EPICA) Dome C ice cores were drilled. We provide a multi-year record of daily precipitation types identified from crystal morphologies, daily precipitation amounts and isotopic composition. Our sampling period (2008-2010) encompasses a warmer year (2009, +1.2 °C with respect to 2 m air temperature long-term average 1996-2010), with larger total precipitation and snowfall amounts (14 and 76 % above sampling period average, respectively), and a colder and drier year (2010, -1.8 °C, 4 % below long-term and sampling period averages, respectively) with larger diamond dust amounts (49 % above sampling period average). Relationships between local meteorological data and precipitation isotopic composition are investigated at daily, monthly and inter-annual scale, and for the different types of precipitation. Water stable isotopes are more closely related to 2 m air temperature than to inversion temperature at all timescales (e.g. R2 = 0.63 and 0.44, respectively for daily values). The slope of the temporal relationship between daily δ18O and 2 m air temperature is approximately 2 times smaller (0.49 ‰ °C-1) than the average Antarctic spatial (0.8 ‰ °C-1) relationship initially used for the interpretation of EPICA Dome C records. In accordance with results from precipitation monitoring at Vostok and Dome F, deuterium excess is anti-correlated with δ18O at daily and monthly scales, reaching maximum values in winter. Hoar frost precipitation samples have a specific fingerprint with more depleted δ18O (about 5 ‰ below average) and higher deuterium excess (about 8 ‰ above average) values than other precipitation

  2. Stable isotope natural abundance of nitrous oxide emitted from Antarctic tundra soils: effects of sea animal excrement depositions.

    PubMed

    Zhu, Renbin; Liu, Yashu; Li, Xianglan; Sun, Jianjun; Xu, Hua; Sun, Liguang

    2008-11-01

    Nitrous oxide (N2O), a greenhouse gas, is mainly emitted from soils during the nitrification and denitrification processes. N2O stable isotope investigations can help to characterize the N2O sources and N2O production mechanisms. N2O isotope measurements have been conducted for different types of global terrestrial ecosystems. However, no isotopic data of N2O emitted from Antarctic tundra ecosystems have been reported although the coastal ice-free tundra around Antarctic continent is the largest sea animal colony on the global scale. Here, we report for the first time stable isotope composition of N2O emitted from Antarctic sea animal colonies (including penguin, seal and skua colonies) and normal tundra soils using in situ field observations and laboratory incubations, and we have analyzed the effects of sea animal excrement depositions on stable isotope natural abundance of N2O. For all the field sites, the soil-emitted N2O was 15N- and 18O-depleted compared with N2O in local ambient air. The mean delta values of the soil-emitted N2O were delta15N = -13.5 +/- 3.2 per thousand and delta18O = 26.2 +/- 1.4 per thousand for the penguin colony, delta15N = -11.5 +/- 5.1 per thousand and delta18O = 26.4 +/- 3.5 per thousand for the skua colony and delta15N = -18.9 +/- 0.7 per thousand and delta18O = 28.8 +/- 1.3 per thousand for the seal colony. In the soil incubations, the isotopic composition of N2O was measured under N2 and under ambient air conditions. The soils incubated under the ambient air emitted very little N2O (2.93 microg N2O--N kg(-1)). Under N2 conditions, much more N2O was formed (9.74 microg N2O--N kg(-1)), and the mean delta15N and delta18O values of N2O were -19.1 +/- 8.0 per thousand and 21.3 +/- 4.3 per thousand, respectively, from penguin colony soils, and -17.0 +/- 4.2 per thousand and 20.6 +/- 3.5 per thousand, respectively, from seal colony soils. The data from in situ field observations and laboratory experiments point to denitrification as the

  3. Stable isotope enrichment in stratospheric nitrous oxide

    SciTech Connect

    Rahn, T.; Wahlen, M.

    1997-12-05

    Nitrous oxide is a greenhouse gas that also plays a role in the cycling of stratospheric ozone. Air samples from the lower stratosphere exhibit {sup 15}N/{sup 14}N and {sup 18}O/{sup 16}O enrichment in nitrous oxide, which can be accounted for with a simple model describing an irreversible destruction process. The observed enrichments are quite large and incompatible with those determined for the main stratospheric nitrous oxide loss processes of photolysis and reaction with excited atomic oxygen. Thus, although no stratospheric source needs to be invoked, the data indicate that present understanding of stratospheric nitrous oxide chemistry is incomplete. 21 refs., 1 fig., 1 tab.

  4. USGS42 and USGS43: human-hair stable hydrogen and oxygen isotopic reference materials and analytical methods for forensic science and implications for published measurement results.

    PubMed

    Coplen, Tyler B; Qi, Haiping

    2012-01-10

    Because there are no internationally distributed stable hydrogen and oxygen isotopic reference materials of human hair, the U.S. Geological Survey (USGS) has prepared two such materials, USGS42 and USGS43. These reference materials span values commonly encountered in human hair stable isotope analysis and are isotopically homogeneous at sample sizes larger than 0.2 mg. USGS42 and USGS43 human-hair isotopic reference materials are intended for calibration of δ(2)H and δ(18)O measurements of unknown human hair by quantifying (1) drift with time, (2) mass-dependent isotopic fractionation, and (3) isotope-ratio-scale contraction. While they are intended for measurements of the stable isotopes of hydrogen and oxygen, they also are suitable for measurements of the stable isotopes of carbon, nitrogen, and sulfur in human and mammalian hair. Preliminary isotopic compositions of the non-exchangeable fractions of these materials are USGS42(Tibetan hair)δ(2)H(VSMOW-SLAP) = -78.5 ± 2.3‰ (n = 62) and δ(18)O(VSMOW-SLAP) = +8.56 ± 0.10‰ (n = 18) USGS42(Indian hair)δ(2)H(VSMOW-SLAP) = -50.3 ± 2.8‰ (n = 64) and δ(18)O(VSMOW-SLAP) = +14.11 ± 0.10‰ (n = 18). Using recommended analytical protocols presented herein for δ(2)H(VSMOW-SLAP) and δ(18)O(VSMOW-SLAP) measurements, the least squares fit regression of 11 human hair reference materials is δ(2)H(VSMOW-SLAP) = 6.085δ(2)O(VSMOW-SLAP) - 136.0‰ with an R-square value of 0.95. The δ(2)H difference between the calibrated results of human hair in this investigation and a commonly accepted human-hair relationship is a remarkable 34‰. It is critical that readers pay attention to the δ(2)H(VSMOW-SLAP) and δ(18)O(VSMOW-SLAP) of isotopic reference materials in publications, and they need to adjust the δ(2)H(VSMOW-SLAP) and δ(18)O(VSMOW-SLAP) measurement results of human hair in previous publications, as needed, to ensure all results on are on the same scales.

  5. USGS42 and USGS43: Human-hair stable hydrogen and oxygen isotopic reference materials and analytical methods for forensic science and implications for published measurement results

    USGS Publications Warehouse

    Coplen, T.B.; Qi, H.

    2012-01-01

    Because there are no internationally distributed stable hydrogen and oxygen isotopic reference materials of human hair, the U.S. Geological Survey (USGS) has prepared two such materials, USGS42 and USGS43. These reference materials span values commonly encountered in human hair stable isotope analysis and are isotopically homogeneous at sample sizes larger than 0.2 mg. USGS42 and USGS43 human-hair isotopic reference materials are intended for calibration of δ(2)H and δ(18)O measurements of unknown human hair by quantifying (1) drift with time, (2) mass-dependent isotopic fractionation, and (3) isotope-ratio-scale contraction. While they are intended for measurements of the stable isotopes of hydrogen and oxygen, they also are suitable for measurements of the stable isotopes of carbon, nitrogen, and sulfur in human and mammalian hair. Preliminary isotopic compositions of the non-exchangeable fractions of these materials are USGS42(Tibetan hair)δ(2)H(VSMOW-SLAP) = -78.5 ± 2.3‰ (n = 62) and δ(18)O(VSMOW-SLAP) = +8.56 ± 0.10‰ (n = 18) USGS42(Indian hair)δ(2)H(VSMOW-SLAP) = -50.3 ± 2.8‰ (n = 64) and δ(18)O(VSMOW-SLAP) = +14.11 ± 0.10‰ (n = 18). Using recommended analytical protocols presented herein for δ(2)H(VSMOW-SLAP) and δ(18)O(VSMOW-SLAP) measurements, the least squares fit regression of 11 human hair reference materials is δ(2)H(VSMOW-SLAP) = 6.085δ(2)O(VSMOW-SLAP) - 136.0‰ with an R-square value of 0.95. The δ(2)H difference between the calibrated results of human hair in this investigation and a commonly accepted human-hair relationship is a remarkable 34‰. It is critical that readers pay attention to the δ(2)H(VSMOW-SLAP) and δ(18)O(VSMOW-SLAP) of isotopic reference materials in publications, and they need to adjust the δ(2)H(VSMOW-SLAP) and δ(18)O(VSMOW-SLAP) measurement results of human hair in previous publications, as needed, to ensure all results on are on the same scales.

  6. A Stable Isotope Study of Fluid-Rock Interactions in the Saddlebag Lake Roof Pendant, Sierra Nevada, California

    NASA Astrophysics Data System (ADS)

    Lojasiewicz, I.; Hartman, S. M.; Holk, G. J.; Paterson, S. R.

    2015-12-01

    The Saddlebag Lake Pendant (SLP) is a ~ 100 km2 zone of Ordovician-Cretaceous metasedimentary and metavolcanic rocks just east of the 95-85 Ma Tuolumne Intrusive Complex (TIC) in the Sierra Nevada of central California. Western SLP and adjacent parts of TIC are affected by the Steelhead Lake Shear Zone (SLSZ), with leucogranitic dikes, abundant qz-tm veins, ductile epidote-chlorite alteration, and massive qz veins. While TIC shows uniform stable isotope values, isotope studies of other Sierra Nevada pendants evidence diversity of fluid sources: Jurassic seawater, Cretaceous magmatic fluids, metamorphic fluids, and meteoric-hydrothermal fluids. We conducted a stable isotope study of 49 samples from units across the SLSZ, focusing on the shear zone. Unlike other pendants, both δ18 O and δD values from SLSZ showed great variability, and most samples were not in isotopic equilibrium. Overall, δ18 O mineral values ranged from -1.5‰(plag) to +15.8‰(bt); mineral δD values ranged from -140‰(tm) to -67‰(bt). TIC δ18 O was +7.8 to +10.0 (plag) and +4.8 to +9.2 (tm), normal magmatic values, and δD were -105 to -75. Paleozoic and Triassic metasedimentary units had most qz δ18 O from +11.3 to +15.8, so within metamorphic range, and δD from -100 to -72 (ep and tm). Jurassic metasedimentary units (Sawmill) and Triassic metavolcanics (Koip) had largest isotopic variability: δ18 O qz from +8.1 to +14.8, plag from -1.1 to +11.8, but ep and tm between +1.3 and +9.3 and δD between -108 and -81. All lower (submagmatic) isotopic values were from a wider, possibly transtensional, part of the SLSZ, transected by Sawmill Canyon. Although TIC and many of the Paleozoic units do not show isotopic evidence for alteration, the Koip and Sawmill units were likely infiltrated by later magmatic waters, and then subjected to very localized meteoric water infiltration in the area surrounding Sawmill Canyon.

  7. Miniature Laser Spectrometer for Stable Isotope Measurements

    NASA Technical Reports Server (NTRS)

    Becker, J. F.; Kojiro, D. R.

    1999-01-01

    As a first step in successfully measuring carbon isotopes optically we have previously demonstrated the measurement of C-13/C-12 to a precision of 0.1% using a tunable diode laser and CO2 spectral lines in the 2300/cm spectral region. This precision of 0.1% (1 per mil) for carbon isotopes is a value sufficiently precise to provide important isotopic data of interest to astrobiologists. The precision presently attainable in gases is sufficient to permit our instrument to be used in the measurement of isotopic ratios of interest to astrobiologists as well as geologists and planetary scientists.

  8. A conceptual model for interpreting δ18O and δD biomarker records from terrestrial archives

    NASA Astrophysics Data System (ADS)

    Zech, Michael; Tuthorn, Mario; Detsch, Florian; Rozanski, Kazimierz; Zech, Roland; Zöller, Ludwig; Zech, Wolfgang; Glaser, Bruno

    2013-04-01

    The natural abundances of stable oxygen (18O/16O) and hydrogen isotopes (D/H) are valuable proxies for reconstructing paleoclimate history on global as well as on regional scale. While stable isotope analyses of sedimentary leaf wax-derived n-alkanes enables establishing δD biomarker records, we recently developed a method based on compound-specific δ18O analyses of hemicellulose sugars (Zech and Glaser, 2009), which now additionally allows establishing δ18O biomarker records from soil/sedimentary organic matter of terrestrial archives. Here we present a conceptual model for interpreting combined δ18O and δD biomarker records (Zech et al., submitted). Based on this model, we suggest that both δ18O and δD biomarker records primarily reflect the isotopic composition of paleoprecipitation modified by evaporative isotope enrichment of leaf water during transpiration. Considering biosynthetic fractionation factors allows reconstructing from combined δ18O and δD biomarker records the leaf water isotopic composition and the deuterium excess of the leaf water. The deuterium excess may serve as proxy for evaporative enrichment and allows reconstructing relative humidity using a Craig-Gordon model. Furthermore, the model allows calculating δ18O of the plant source water (δ18Osource water), which can be assumed to primarily reflect δ18O of paleoprecipitation. Hence, paleoclimatic conclusions in terms of temperature can be drawn in high latitude study areas and precipitation amount can be reconstructed in monsoon regions. Zech, M., Glaser, B., 2009. Compound-specific δ18O analyses of neutral sugars in soils using GC-Py-IRMS: problems, possible solutions and a first application. Rapid Commun. Mass Spectrom. 23, 3522-3532. Zech et al., 2013. A 220 ka terrestrial δ18O and deuterium excess biomarker record from an eolian permafrost paleosol sequence, NE-Siberia. Submitted to Chemical Geology.

  9. Stable oxygen isotope reconstruction of ambient temperature during the collapse of a cod (Gadus morhua) fishery.

    PubMed

    Jones, J Brin; Campana, Steven E

    2009-09-01

    Changing environmental conditions set against a backdrop of high exploitation can result in severe consequences for commercially harvested stocks. The collapse of the Eastern Scotian Shelf cod (Gadus morhua L.) off eastern Canada was primarily due to overexploitation but may have been exacerbated by a widespread temperature decline. Recent studies have called for accurate determination of ambient temperature (the actual temperature exposure history of the fish) before discarding environmental conditions as a factor in the collapse. We used the stable oxygen isotope composition of otoliths (delta18O(oto)) to reconstruct the ambient temperature history of Eastern Scotian Shelf cod from 1970 to 2000 in order to determine whether the stock experienced the temperature decline or shifted their distribution to avoid it. To correct delta18O(oto) for seawater isotope content (deltaO(w)), we generated a new meta-equation for the relationship between delta18O(w) (per mil) and salinity (S, in psu) on the Eastern Scotian Shelf: delta18O(w) = 0.539 x S - 18.790. The ambient temperature series revealed that the large-scale geographic distribution of mature cod remained constant through the cooling period, although their ambient temperature was cooler than expected in warmer periods and warmer than expected in cooler periods, indicating small-scale thermoregulatory movement. Although the mean hydrographic temperature was 4 degrees C, mature cod usually inhabited the coldest available waters (mean ambient temperature = 3 degrees C), while the juveniles usually inhabited warmer waters (mean ambient temperature = 5.5 degrees C). Length-at-age was significantly related to ambient temperature, especially in the early years of growth, and therefore declining ambient temperatures were at least partially responsible for declines in asymptotic length (up to age 8 yr). The most active thermoregulatory movement occurred during a moderate warming period; therefore extreme warming events (such

  10. Recent Advances in Stable Isotope Techniques for N2O Source Partitioning in Soils

    NASA Astrophysics Data System (ADS)

    Baggs, E.; Mair, L.; Mahmood, S.

    2007-12-01

    The use of 13C, 15N and 18O enables us to overcome uncertainties associated with soil C and N processes and to assess the links between species diversity and ecosystem function. Recent advances in stable isotope techniques enable determination of process rates, and are fundamental for examining interactions between C and N cycles. Here we will introduce the 15N-, 18O- and 13C-enrichment techniques we have developed to distinguish between different N2O-producing processes in situ in soils, presenting selected results, and will critically assess their potential, alone and in combination with molecular techniques, to help address key research questions for soil biogeochemistry and microbial ecology. We have developed 15N- 18O-enrichment techniques to distinguish between, and to quantify, N2O production during ammonia oxidation, nitrifier denitrification and denitrification. This provides a great advantage over natural abundance approaches as it enables quantification of N2O from each microbial source, which can be coupled with quantification of N2 production, and used to examine interactions between different processes and cycles. These approaches have also provided new insights into the N cycle and how it interacts with the C cycle. For example, we now know that ammonia oxidising bacteria significantly contribute to N2O emissions from soils, both via the traditionally accepted ammonia oxidation pathway, and also via denitrification (nitrifier denitrification) which can proceed even under aerobic conditions. We are also linking emissions from each source to diversity and activity of relevant microbial functional groups, for example through the development and application of a specific nirK primer for the nitrite reductase in ammonia oxidising bacteria. Recently, isotopomers have been proposed as an alternative for source partitioning N2O at natural abundance levels, and offers the potential to investigate N2O production from nitrate ammonification, and overcomes the

  11. Metal stable isotopes in low-temperature systems: A primer

    USGS Publications Warehouse

    Bullen, T.D.; Eisenhauer, A.

    2009-01-01

    Recent advances in mass spectrometry have allowed isotope scientists to precisely determine stable isotope variations in the metallic elements. Biologically infl uenced and truly inorganic isotope fractionation processes have been demonstrated over the mass range of metals. This Elements issue provides an overview of the application of metal stable isotopes to low-temperature systems, which extend across the borders of several science disciplines: geology, hydrology, biology, environmental science, and biomedicine. Information on instrumentation, fractionation processes, data-reporting terminology, and reference materials presented here will help the reader to better understand this rapidly evolving field.

  12. Stable isotopes in alpine precipitation as tracers of atmospheric deposition

    NASA Astrophysics Data System (ADS)

    Wasiuta, V. L.; Lafreniere, M. J.; Kyser, T. K.; Norman, A. L.; Mayer, B.; Wieser, M.

    2010-12-01

    Alpine ecosystems, which are generally nutrient poor and exist under extreme climatic conditions, are particularly sensitive to environmental and climatic stressors. Studies in the USA Rocky Mountains and European Alps have shown that alpine terrestrial and aquatic ecosystems are particularly sensitive to enhanced deposition of reactive nitrogen and can show ecologically destructive responses at relatively low levels of nitrogen deposition. However, there is no base line for atmospheric deposition of natural and anthropogenic contaminants in the Canadian alpine. Preliminary results of isotopic and chemical analyses of precipitation from an elevational transect on a glaciated alpine site in the Canadian Rockies are presented. Precipitation accumulating from early autumn through to spring (2008/2009 and 2009/2010) was sampled by means of seasonal snow cover on alpine glaciers. Summer precipitation was sampled through July and August 2010 using bulk collectors installed at the sites of winter sampling. The isotope ratios of dissolved sulphate (δ34S, δ18O), nitrogen (δ15N, δ18O), as well as precipitation (δ2H, δ18O) are utilized in addition to major ion concentrations and trace metal concentrations. Results from 2008/2009 snowpack samples indicate a strong seasonal trend in sulphate (SO42-) and nitrogen (NO3-) deposition which is consistent across the altitudinal transect. Snow horizons representing early autumn and spring precipitation show higher SO42- and NO3- concentrations in contrast to lower concentrations in winter horizons. The aforementioned suite of isotopic and chemical analyses are used to investigate the variability in dominant geographic source regions for atmospheric SO42- and NO3- (local, regional, or long range transported contaminants), as well as to identify contributions from the major biogeochemical source types (e.g. hydrocarbon combustion, lithogenic dust, agricultural emissions).

  13. Stable Isotopes of Carbon Monoxide in an Urban Environment: A Study at Indianapolis, IN as part of the INFLUX Campaign

    NASA Astrophysics Data System (ADS)

    Vimont, I.; Petrenko, V. V.; Turnbull, J. C.; Place, P.; White, J. W. C.; Karion, A.

    2015-12-01

    We have developed a new system capable of measuring stable isotopes of carbon monoxide (CO) in small atmospheric samples. Measurements at 3 tall tower sites in Indianapolis, IN, USA have been ongoing since July 2013 as part of the INdianapolis FLUX (INFLUX) project. These three towers consist of an upwind, or background site, a site in the urban center, and a site on the downwind edge of the city. The tower collections are discrete, one hour integrated samples taken using NOAA's Portable Flask Package system. These sites have been measured for CO mole fraction, 13CO, and C18O approximately 6 times per month. We present a time series of data from these three sites, as well as a source analysis of the CO produced during the winter months (the winter data allow the use of several simplifying assumptions). We have identified mobile (vehicular) fossil fuel emissions as the only clearly significant wintertime source of CO, and quantified the stable isotopic signature of that source. We also present data from a traffic study done in March of 2015. A vehicle-based collection system was used for this study, and both continuous CO mole fraction and discrete CO mole fraction, 13CO, and C18O measurements were made. The results for CO stable isotopes are consistent with the vehicular emission CO isotopic signatures inferred from the tower samples.

  14. Fe-O stable isotope pairs elucidate a high-temperature origin of Chilean iron oxide-apatite deposits

    NASA Astrophysics Data System (ADS)

    Bilenker, Laura D.; Simon, Adam C.; Reich, Martin; Lundstrom, Craig C.; Gajos, Norbert; Bindeman, Ilya; Barra, Fernando; Munizaga, Rodrigo

    2016-03-01

    Iron oxide-apatite (IOA) ore deposits occur globally and can host millions to billions of tons of Fe in addition to economic reserves of other metals such as rare earth elements, which are critical for the expected growth of technology and renewable energy resources. In this study, we pair the stable Fe and O isotope compositions of magnetite samples from several IOA deposits to constrain the source reservoir of these elements in IOAs. Since magnetite constitutes up to 90 modal% of many IOAs, identifying the source of Fe and O within the magnetite may elucidate high-temperature and/or lower-temperature processes responsible for their formation. Here, we focus on the world-class Los Colorados IOA in the Chilean iron belt (CIB), and present data for magnetite from other Fe oxide deposits in the CIB (El Laco, Mariela). We also report Fe and O isotopic values for other IOA deposits, including Mineville, New York (USA) and the type locale, Kiruna (Sweden). The ranges of Fe isotopic composition (δ56Fe, 56Fe/54Fe relative to IRMM-14) of magnetite from the Chilean deposits are: Los Colorados, δ56Fe (±2σ) = 0.08 ± 0.03‰ to 0.24 ± 0.08‰; El Laco, δ56Fe = 0.20 ± 0.03‰ to 0.53 ± 0.03‰; Mariela, δ56Fe = 0.13 ± 0.03‰. The O isotopic composition (δ18O, 18O/16O relative to VSMOW) of the same Chilean magnetite samples are: Los Colorados, δ18O (±2σ) = 1.92 ± 0.08‰ to 3.17 ± 0.03‰; El Laco, δ18O = 4.00 ± 0.10‰ to 4.34 ± 0.10‰; Mariela, δ18O = (1.48 ± 0.04‰). The δ18O and δ56Fe values for Kiruna magnetite yield an average of 1.76 ± 0.25‰ and 0.16 ± 0.07‰, respectively. The Fe and O isotope data from the Chilean IOAs fit unequivocally within the range of magnetite formed by high-temperature magmatic or magmatic-hydrothermal processes (i.e., δ56Fe 0.06-0.49‰ and δ18O = 1.0-4.5‰), consistent with a high-temperature origin for Chilean IOA deposits. Additionally, minimum formation temperatures calculated by using the measured Δ18O

  15. Ice-wedge based permafrost chronologies and stable-water isotope records from Arctic Siberia

    NASA Astrophysics Data System (ADS)

    Wetterich, Sebastian; Opel, Thomas; Meyer, Hanno; Schwamborn, Georg; Schirrmeister, Lutz; Dereviagin, Alexander Yu.

    2016-04-01

    Late Quaternary permafrost of northern latitudes contains large proportions of ground ice, including pore ice, segregation ice, massive ice, buried glacier ice and in particular ice wedges. Fossil ice-wedges are remnants of polygonal patterned ground in former tundra areas, which evolved over several tens of thousands of years in non-glaciated Beringia. Ice wedges originate from repeated frost cracking of the ground in winter and subsequent crack filling by snowmelt and re-freezing in the ground in spring. Hence, the stable water isotope composition (δ18O, δD, d excess) of wedge ice derives from winter precipitation and is commonly interpreted as wintertime climate proxy. Paleoclimate studies based on ice-wedge isotope data cover different timescales and periods of the late Quaternary. (MIS 6 to MIS 1). In the long-term scale the temporal resolution is rather low and corresponds to mid- and late Pleistocene and Holocene stratigraphic units. Recent progress has been made in developing centennial Late Glacial and Holocene time series of ice-wedge stable isotopes by applying radiocarbon dating of organic remains in ice samples. Ice wedges exposed at both coasts of the Dmitry Laptev Strait (East Siberian Sea) were studied to deduce winter climate conditions since about 200 kyr. Ice wedges aligned to distinct late Quaternary permafrost strata were studied for their isotopic composition and dated by radiocarbon ages of organic matter within the wedge ice or by cosmogenic nuclide ratios (36Cl/Cl-) of the ice. The paleoclimate interpretation is furthermore based on geocryological and paleoecological proxy data and geochronological information (radiocarbon, luminescence, radioisotope disequilibria 230Th/U) from ice-wedge embedding frozen deposits. Coldest winter conditions are mirrored by most negative δ18O mean values of -37 ‰ and δD mean values of -290 ‰ from ice wedges of the Last Glacial Maximum (26 to 22 kyr BP) while late Holocene (since about 4 kyr BP) and in

  16. Stable isotope chemistry of fossil bone as a new paleoclimate indicator

    NASA Astrophysics Data System (ADS)

    Kohn, Matthew J.; Law, J. Mclver

    2006-02-01

    During fossilization, bone is thought to recrystallize and alter chemically on timescales of kyr to a few tens of kyr, i.e., similar to the timescale for formation of soils. Therefore, C- and O-isotope compositions of bone apatite should correlate with trends in soil water composition and aridity, and serve as paleoclimate indicators. This hypothesis was tested by analyzing C- and O-isotope compositions of the CO 3 component of fossil bone apatite from mid-Oligocene through late Pleistocene units in Oregon and western Idaho, including the John Day (19.4-30.0 Ma), Mascall (15.2-15.8 Ma), and Rattlesnake (7.2-7.8 Ma) Formations, whose paleosol sequences have been studied in detail, and the Juntura (10-11 Ma), Hagerman (3.2 Ma), and Fossil Lake (<23-650 ka) fossil localities. Tooth enamel δ18O values provide a baseline of meteoric water compositions. Stable isotope compositions of bone CO 3 do change in response to broad climatic trends, but show poor correlation with compositions of corresponding paleosol CO 3 at specific horizons. Instead, compositional deviations between bone and paleosol CO 3 correlate with compositional deviations with the next higher paleosol; this suggests that the timescale for fossilization exceeds one paleosol cycle. Based on stratigraphic evidence and simple alteration models, fossilization timescales are estimated at 20-50 kyr, indicating that bone CO 3 will prove most useful for sequences spanning >100 kyr. C-isotopes show negative and strong positive deviations during wet and dry climates respectively, and short-term trends correspond well with changes in aridity within the Mascall and Rattlesnake Formations, as inferred from paleosols. A proposed correction to δ18O values based on δ13C anomalies implies a small, ˜1.5‰ increase in meteoric water δ18O during the late Oligocene global warming event, consistent with a minimum temperature increase of ˜4 °C. A strong inferred decrease in δ18O of 4-5‰ after 7 Ma closely parallels

  17. Environmental and biomedical applications of natural metal stable isotope variations

    USGS Publications Warehouse

    Bullen, T.D.; Walczyk, T.

    2009-01-01

    etal stable isotopes are now being used to trace metal contaminants in the environment and as indicators of human systemic function where metals play a role. Stable isotope abundance variations provide information about metal sources and the processes affecting metals in complex natural systems, complementing information gained from surrogate tracers, such as metal abundance ratios or biochemical markers of metal metabolism. The science is still in its infancy, but the results of initial studies confirm that metal stable isotopes can provide a powerful tool for forensic and biomedical investigations.

  18. Stable Isotopes In Fossil Mammals, Fish and Shells From Kunlun Pass Basin, Tibetan Plateau: Paleoclimatic and paleoelevation implications

    NASA Astrophysics Data System (ADS)

    Wang, Y.; Wang, X.; Xu, Y.; Zhang, C.; Li, Q.; Tseng, Z.; Takeuchi, G.; Deng, T.

    2008-05-01

    Stable carbon and oxygen isotope analyses of both terrestrial and aquatic fossils reveal a drastic change in habitat and hydrological regime in the Kunlun Pass Basin on the northern Tibetan Plateau since the late Pliocene. The δ13C values of both serial and bulk enamel samples from fossil herbivore teeth suggest that C4 grasses (i.e., warm climate grasses) were likely present in local ecosystems at the end of the Pliocene, around 2.0-2.5 Ma. The carbon isotopic variations among different species indicate mix habitats, including grasslands and wooded grasslands, occupied and partitioned by different species, consistent with palynological evidence. The anti-correlation between δ13C and δ18O values observed in the fossil teeth suggests that summer monsoons were a major source of moisture for the area in the late Pliocene. The more negative enamel-δ18O values of large herbivores in the late Pliocene suggest that paleo-meteoric water then was more depleted in 18O compared to the present-day meteoric water in the basin. The most likely cause for this δ18O shift in tooth enamel or water after the late Pliocene is a drastic change in the regional hydrological cycle (e.g., change in source and rainout history of atmospheric moisture or atmospheric circulation pattern, increasing aridity, and etc.) possibly due to tectonic and climate change. Our carbon and oxygen isotope data, in conjunction with geological/fossil evidence, suggest that the Kunlun Pass Basin had a much warmer and wetter climate in the late Pliocene, quite different from today's rock desert and cold steppe environments. The paleo-temperature estimates based on the δ18O values of fossil bones and paleo- meteoric water, if valid, would imply that the present-day high elevation of the basin was established after 2-3 Ma.

  19. Compound specific stable isotope analysis vs. bulk stable isotope analysis of agricultural food products

    NASA Astrophysics Data System (ADS)

    Psomiadis, David; Horváth, Balázs; Nehlich, Olaf; Bodiselitsch, Bernd

    2015-04-01

    The bulk analysis of stable isotopes (carbon, nitrogen, sulphur, oxygen and hydrogen) from food staples is a common tool for inferring origin and/or fraud of food products. Many studies have shown that bulk isotope analyses of agricultural products are able to separate large geographical areas of food origin. However, in micro-localities (regions, districts, and small ranges) these general applications fail in precision and discriminative power. The application of compound specific analysis of specific components of food products helps to increase the precision of established models. Compound groups like fatty acids (FAMEs), vitamins or amino acids can help to add further detailed information on physiological pathways and local conditions (micro-climate, soil, water availability) and therefore might add further information for the separation of micro-localities. In this study we are aiming to demonstrate the power and surplus of information of compound specific isotope analysis in comparison to bulk analysis of agricultural products (e.g. olive oil, cereal crops or similar products) and discuss the advantages and disadvantages of such (labor intense) analysis methods. Here we want to identify tools for further detailed analysis of specific compounds with high powers of region separation for better prediction models.

  20. Molecular isotopic engineering (MIE): industrial manufacture of naproxen of predetermined stable carbon-isotopic compositions for authenticity and security protection and intellectual property considerations

    NASA Astrophysics Data System (ADS)

    Jasper, J. P.; Farina, P.; Pearson, A.; Mezes, P. S.; Sabatelli, A. D.

    2016-05-01

    Molecular Isotopic Engineering (MIE) is the directed stable-isotopic synthesis of chemical products for reasons of product identification and of product security, and also for intellectual property considerations. We report here a generally excellent correspondence between the observed and predicted stable carbon-isotopic (δ13C) results for a successful directed synthesis of racemic mixture from its immediate precursors. The observed results are readily explained by the laws of mass balance and isotope mass balance. Oxygen- and hydrogen isotopic results which require an additional assessment of the effects of O and H exchange, presumably due to interaction with water in the reaction solution, are addressed elsewhere. A previous, cooperative study with the US FDA-DPA showed that individual manufacturers of naproxen could readily be differentiated by their stable-isotopic provenance (δ13C, δ18O, and δD ref. 1). We suggest that MIE can be readily employed in the bio/pharmaceutical industry without alteration of present manufacturing processes other than isotopically selecting and/or monitoring reactants and products.

  1. Water Stable Isotopes: Atmospheric Composition and Applications in Polar Ice Core Studies

    NASA Astrophysics Data System (ADS)

    Jouzel, J.

    2003-12-01

    Natural waters formed of ˜99.7% of H216O are also constituted of other stable isotopic molecules, mainly H218O (˜2‰), H217O (˜0.5‰), and HD16O (˜0.3‰), where H and D (deuterium) correspond to 1H and 2H, respectively. Owing to slight differences in physical properties of these molecules, essentially their saturation vapor pressure, and their molecular diffusivity in air, fractionation processes occur at each phase change of the water except sublimation and melting of compact ice. As a result, the distribution of these water isotopes varies both spatially and temporally in the atmosphere, in the precipitation, and, in turn, in the various reservoirs of the hydrosphere and of the cryosphere. These isotopic variations have applications in such fields as climatology and cloud physics. More importantly, they are at the origin of two now well-established disciplines: isotope hydrology and isotope paleoclimatology. The various aspects dealing with isotope hydrology are reviewed by Kendall (see Chapter 5.11). In this chapter, we focus on this field known as "isotope paleoclimatology." As the behavior of H217O in the atmospheric water is very similar to that of H218O (more abundant and easier to precisely determine), isotope paleoclimatology is only based on the changes in concentrations of HDO and H218O. These concentrations are given with respect to a standard as δ=(Rsample-RSMOW)/RSMOW and expressed in per mil δ units (δD and δ18O, respectively). In this definition, Rsample and RSMOW are the isotopic ratios of the sample and of the Vienna Standard Mean Ocean Water (V-SMOW) with D/H and 18O/16O atomic ratios of 155.76×10-6 and 2005.2×10-6, respectively (Hageman et al., 1970; Baerstchi, 1976; Gonfiantini, 1978).The use of water stable isotopes in paleoclimatology is based on the fact that their present-day distribution in precipitation is strongly related to climatological parameters. Of primary interest is the linear relationship between annual values of

  2. Small Tails Tell Tall Tales – Intra-Individual Variation in the Stable Isotope Values of Fish Fin

    PubMed Central

    Hayden, Brian; Soto, David X.; Jardine, Tim D.; Graham, Brittany S.; Cunjak, Richard A.; Romakkaniemi, Atso; Linnansaari, Tommi

    2015-01-01

    Background Fish fin is a widely used, non-lethal sample material in studies using stable isotopes to assess the ecology of fishes. However, fish fin is composed of two distinct tissues (ray and membrane) which may have different stable isotope values and are not homogeneously distributed within a fin. As such, estimates of the stable isotope values of a fish may vary according to the section of fin sampled. Methods To assess the magnitude of this variation, we analysed carbon (δ13C), nitrogen (δ15N), hydrogen (δ2H) and oxygen (δ18O) stable isotopes of caudal fin from juvenile, riverine stages of Atlantic salmon (Salmo salar) and brown trout (Salmo trutta). Individual fins were sub-sectioned into tip, mid and base, of which a further subset were divided into ray and membrane. Findings Isotope variation between fin sections, evident in all four elements, was primarily related to differences between ray and membrane. Base sections were13C depleted relative to tip (~ 1 ‰) with equivalent variation evident between ray and membrane. A similar trend was evident in δ2H, though the degree of variation was far greater (~ 10 ‰). Base and ray sections were 18O enriched (~ 2 ‰) relative to tip and membrane, respectively. Ray and membrane sections displayed longitudinal variation in 15N mirroring that of composite fin (~ 1 ‰), indicating that variation in15N values was likely related to ontogenetic variation. Conclusions To account for the effects of intra-fin variability in stable isotope analyses we suggest that researchers sampling fish fin, in increasing priority, 1) also analyse muscle (or liver) tissue from a subsample of fish to calibrate their data, or 2) standardize sampling by selecting tissue only from the extreme tip of a fin, or 3) homogenize fins prior to analysis. PMID:26670464

  3. A biomarker based on the stable isotopes of nickel

    PubMed Central

    Cameron, Vyllinniskii; Vance, Derek; Archer, Corey; House, Christopher H.

    2009-01-01

    The new stable isotope systems of transition metals are increasingly used to understand and quantify the impact of primitive microbial metabolisms on the modern and ancient Earth. To date, little effort has been expended on nickel (Ni) isotopes but there are good reasons to believe that this system may be more straightforward, and useful in this respect, than some others. Here, we present Ni stable isotope data for abiotic terrestrial samples and pure cultures of methanogens. The dataset for rocks reveals little isotopic variability and provides a lithologic baseline for terrestrial Ni isotope studies. In contrast, methanogens assimilate the light isotopes, yielding residual media with a complementary heavy isotopic enrichment. Methanogenesis may have evolved during or before the Archean, when methane could have been key to Earth's early systems. Our data suggest significant potential in Ni stable isotopes for identifying and quantifying methanogenesis on the early planet. Additionally, Ni stable isotope fractionation may well prove to be the fundamental unambiguous trace metal biomarker for methanogens. PMID:19553218

  4. A biomarker based on the stable isotopes of nickel.

    PubMed

    Cameron, Vyllinniskii; Vance, Derek; Archer, Corey; House, Christopher H

    2009-07-01

    The new stable isotope systems of transition metals are increasingly used to understand and quantify the impact of primitive microbial metabolisms on the modern and ancient Earth. To date, little effort has been expended on nickel (Ni) isotopes but there are good reasons to believe that this system may be more straightforward, and useful in this respect, than some others. Here, we present Ni stable isotope data for abiotic terrestrial samples and pure cultures of methanogens. The dataset for rocks reveals little isotopic variability and provides a lithologic baseline for terrestrial Ni isotope studies. In contrast, methanogens assimilate the light isotopes, yielding residual media with a complementary heavy isotopic enrichment. Methanogenesis may have evolved during or before the Archean, when methane could have been key to Earth's early systems. Our data suggest significant potential in Ni stable isotopes for identifying and quantifying methanogenesis on the early planet. Additionally, Ni stable isotope fractionation may well prove to be the fundamental unambiguous trace metal biomarker for methanogens.

  5. Metal stable isotope signatures as tracers in environmental geochemistry.

    PubMed

    Wiederhold, Jan G

    2015-03-01

    The biogeochemical cycling of metals in natural systems is often accompanied by stable isotope fractionation which can now be measured due to recent analytical advances. In consequence, a new research field has emerged over the last two decades, complementing the traditional stable isotope systems (H, C, O, N, S) with many more elements across the periodic table (Li, B, Mg, Si, Cl, Ca, Ti, V, Cr, Fe, Ni, Cu, Zn, Ge, Se, Br, Sr, Mo, Ag, Cd, Sn, Sb, Te, Ba, W, Pt, Hg, Tl, U) which are being explored and potentially applicable as novel geochemical tracers. This review presents the application of metal stable isotopes as source and process tracers in environmental studies, in particular by using mixing and Rayleigh model approaches. The most important concepts of mass-dependent and mass-independent metal stable isotope fractionation are introduced, and the extent of natural isotopic variations for different elements is compared. A particular focus lies on a discussion of processes (redox transformations, complexation, sorption, precipitation, dissolution, evaporation, diffusion, biological cycling) which are able to induce metal stable isotope fractionation in environmental systems. Additionally, the usefulness and limitations of metal stable isotope signatures as tracers in environmental geochemistry are discussed and future perspectives presented.

  6. Metal stable isotope signatures as tracers in environmental geochemistry.

    PubMed

    Wiederhold, Jan G

    2015-03-01

    The biogeochemical cycling of metals in natural systems is often accompanied by stable isotope fractionation which can now be measured due to recent analytical advances. In consequence, a new research field has emerged over the last two decades, complementing the traditional stable isotope systems (H, C, O, N, S) with many more elements across the periodic table (Li, B, Mg, Si, Cl, Ca, Ti, V, Cr, Fe, Ni, Cu, Zn, Ge, Se, Br, Sr, Mo, Ag, Cd, Sn, Sb, Te, Ba, W, Pt, Hg, Tl, U) which are being explored and potentially applicable as novel geochemical tracers. This review presents the application of metal stable isotopes as source and process tracers in environmental studies, in particular by using mixing and Rayleigh model approaches. The most important concepts of mass-dependent and mass-independent metal stable isotope fractionation are introduced, and the extent of natural isotopic variations for different elements is compared. A particular focus lies on a discussion of processes (redox transformations, complexation, sorption, precipitation, dissolution, evaporation, diffusion, biological cycling) which are able to induce metal stable isotope fractionation in environmental systems. Additionally, the usefulness and limitations of metal stable isotope signatures as tracers in environmental geochemistry are discussed and future perspectives presented. PMID:25640608

  7. Influence of mass transfer on stable isotope fractionation.

    PubMed

    Thullner, Martin; Fischer, Anko; Richnow, Hans-Hermann; Wick, Lukas Y

    2013-01-01

    Biodegradation of contaminants is a common remediation strategy for subsurface environments. To monitor the success of such remediation means a quantitative assessment of biodegradation at the field scale is required. Nevertheless, the reliable quantification of the in situ biodegradation process it is still a major challenge. Compound-specific stable isotope analysis has become an established method for the qualitative analysis of biodegradation in the field and this method is also proposed for a quantitative analysis. However, to use stable isotope data to obtain quantitative information on in situ biodegradation requires among others knowledge on the influence of mass transfer processes on the observed stable isotope fractionation. This paper reviews recent findings on the influence of mass transfer processes on stable isotope fractionation and on the quantitative interpretation of isotope data. Focus will be given on small-scale mass transfer processes controlling the bioavailability of contaminants. Such bioavailability limitations are known to affect the biodegradation rate and have recently been shown to affect stable isotope fractionation, too. Theoretical as well as experimental studies addressing the link between bioavailability and stable isotope fractionation are reviewed and the implications for assessing biodegradation in the field are discussed.

  8. Tritium and Stable Isotopes of Precipitation and Surface Water in California

    NASA Astrophysics Data System (ADS)

    Harms, P.; Moran, J. E.; Visser, A.; Esser, B. K.

    2014-12-01

    Tritium (3H) and stable isotopes (2H and 18O) are effective natural tracers of water molecules through the hydrologic system. The strong topographic gradient in California results in distinct isotopic signatures that are particularly effective in watershed studies. Past studies of meteoric tritium distribution within the United States have focused on large-scale trends, at low spatial resolution. Globally, tritium in precipitation is monitored by the International Atomic Energy Agency contributing to the Global Network of Isotopes in Precipitation (GNIP) database. The two tritium monitoring stations in California contributing to the GNIP database were discontinued in 1976 (Santa Maria) and 1993 (Menlo Park). Surface water studies have focused on time series in major rivers nationwide or localized studies. Our study focuses on high spatial resolution water isotope data collection in California. Over 140 tritium and stable water isotope samples were collected from surface water and direct precipitation during the 2013 Summer/Fall and 2014 Winter/Spring flow regimes and analyzed by helium accumulation and noble gas mass spectrometry. Surface water samples are collected as a proxy for precipitation and to investigate trends related to water residence times. Tritium concentrations in precipitation show strong spatial trends, with higher concentrations at inland high elevation locations. Surface water tritium trends with spatial location (latitude and longitude) and elevation (reflecting the precipitation signal) and distance downstream (reflecting water residence times). A local meteoric water line (MWL) for California is developed from stable isotope data and analyzed in comparison to the global MWL. Results have implications for tritium tracer and water provenance studies.

  9. Spatial and temporal variability of stable isotopes and biological parameters for the Danube River in Serbia.

    PubMed

    Mitrovic, Tatjana; Obradovic, Vesna; Golobocanin, Dusan; Ogrinc, Nives; Miljevic, Nada

    2010-06-01

    This paper presents the results of hydrological, physicochemical, biological, and isotopic investigations of the Danube River along the stretch through Serbian territory conducted during four campaigns in September and November 2007, September 2008 and April 2009. The stable isotope values exhibited significant changes both in the Danube (-10.7 to-9.5 per thousand for delta(18)O and-73.7 to-67.1 per thousand for delta(2)H) and in its tributaries (-9.1 to-8.5 per thousand for delta(18)O and-69.4 to-59.4 per thousand for delta(2)H) depending on the time of survey, which could be partly attributed to the influences of seasonal effects. Results emphasise the dominant role of tributaries inflows from aquifers along the Danube. The very narrow range of delta(13)C(POC) (from-28.9 to-27.4 per thousand) was associated with relatively high C/N ratios (C/N>9), and together with delta(15)N(TPN) values, the date suggested that, in early spring, a major fraction of particulate organic matter was derived from allochthonous matter. An orthogonal varimax rotation of the principal components analysis identified four latent factors ('mineral related', 'biological', 'hardness', and 'soil inlets') which are responsible for the data structure covering 79% of the observed variations among the variables studied. A reliable grouping of samples with respect to the season was found.

  10. Stable Isotopes (O, H, and S) in the Muteh Gold Deposit, Golpaygan Area, Iran

    SciTech Connect

    Abdollahi, M. J. Karimpour, M. H.; Kheradmand, A.; Zarasvandi, A. R.

    2009-06-15

    The Muteh gold district with nine gold deposits is located in the Sanandaj-Sirjan metamorphic zone. Gold mineralization occurs in a pre-Permian complex which mainly consists of green schists, meta-volcanics, and gneiss rocks. Shear zones are the host of gold mineralization. Gold paragenesis minerals include pyrite, chalcopyrite, pyrrhotite, and secondary minerals. Pyrites occur as pre-, syn-, and post-metamorphism minerals. To determine the source of the ore-bearing fluids, fifty samples were selected for petrographical and stable isotope studies. The mean values of 12.4 per mille , and -42 per mille for {delta}{sup 18}O and {delta}D isotopes, respectively, and a mean value of 7.75 per mille of calculated fractionation factors for {delta}{sup 18}O H{sub 2}O, from quartz veins indicate that metamorphic host rocks are the most important source for the fluids and gold mineralization. Three generations of pyrite can be distinguished showing a wide range of {delta}{sup 34}S. Gold mineralization is closely associated with intense hydrothermal alteration along the ductile shear zones. The characteristics of the gold mineralization in the study area are similar to those of orogenic gold deposits elsewhere.

  11. Proxy Records of the Indonesian Low and the El Ni{tilde n}o-Southern Oscillation (ENSO) from Stable Isotope Measurements of Indonesian Reef Corals

    SciTech Connect

    Moore, M.D.

    1995-12-31

    The Earth`s largest atmospheric convective center is the Indonesian Low. It generates the Australasian monsoon, drives the zonal tropospheric Walker Circulation, and is implicated in the genesis of the El Nino-Southern Oscillation (ENSO). The long-term variability of the Indonesian Low is poorly characterized, yet such information is crucial for evaluating whether changes in the strength and frequency of ENSO events are a possible manifestation of global warming. Stable oxygen isotope ratios ({delta}{sup 18}O) in shallow-water reef coral skeletons track topical convective activity over hundreds of years because the input of isotopically-depleted rainwater dilutes seawater {delta}{sup 18}O. Corals also impose a temperature-dependent fractionation on {delta}{sup 18}O, but where annual rainfall is high and sea surface temperature (SST) variability is low the freshwater flux effect dominates.

  12. Spatial-temporal changes in Andean plateau climate and elevation from stable isotopes of mammal teeth

    NASA Astrophysics Data System (ADS)

    Bershaw, John; Garzione, Carmala N.; Higgins, Pennilyn; MacFadden, Bruce J.; Anaya, Frederico; Alvarenga, Herculano

    2010-01-01

    Paleoelevation constraints from fossil leaf physiognomy and stable isotopes of sedimentary carbonate suggest that significant surface uplift of the northern Andean plateau, on the order of 2.5 ± 1 km, occurred between ˜ 10.3 and 6.4 Ma. Independent spatial and temporal constraints on paleoelevation and paleoclimate of both the northern and southern plateau are important for understanding the distribution of rapid surface uplift and its relation to climate evolution across the plateau. This study focuses on teeth from modern and extinct mammal taxa (including notoungulates, pyrotheres, and litopterns) spanning ˜ 29 Ma to present, collected from the Altiplano and Eastern Cordillera of Bolivia (16.2°S to 21.4°S), and lowland Brazil. Tooth enamel of large, water-dependent mammals preserves a record of surface water isotopes and the type of plants that animals ingested while their teeth were mineralizing. Previous studies have shown that the δ18O of modern precipitation and surface waters decrease systematically with increasing elevations across the central Andes. Our results from high elevation sites between 3600 and 4100 m show substantially more positive δ18O values for late Oligocene tooth samples compared to < 10 Ma tooth δ18O values. Late Oligocene teeth collected from low elevation sites in southeast Brazil show δ18O values similar (within 2‰) to contemporaneous teeth collected at high elevation in the Eastern Cordillera. This affirms that the Andean plateau was at a very low elevation during the late Oligocene. Late Oligocene teeth from the northern Eastern Cordillera also yield consistent δ13C values of about - 9‰, indicating that the environment was semi-arid at that time. Latitudinal gradients in δ18O values of late Miocene to Pliocene fossil teeth are similar to modern values for large mammals, suggesting that by ˜ 8 Ma in the northern Altiplano and by ˜ 3.6 Ma in the southern Altiplano, both regions had reached high elevation and

  13. Foraminiferal stable isotope constraints on salinity changes in the deglacial and early Holocene Baltic Sea region

    NASA Astrophysics Data System (ADS)

    Quintana Krupinski, Nadine; Filipsson, Helena; Bokhari-Friberg, Yasmin; Knudsen, Karen-Luise; Mackensen, Andreas; Groeneveld, Jeroen; Austin, William

    2015-04-01

    The northern European Baltic Sea shows evidence of strong coupling with North Atlantic climate over recent glacial-interglacial cycles, but existing climate proxy evidence from regional sediment records suggest that the coupling may occur through non-linear processes. High-resolution regional climate records in Europe and from the Baltic Sea are critical for evaluating this coupling and the regional sensitivity to North Atlantic and global climate signals. However, evaluating the drivers and mechanisms of proposed links between the North Atlantic and Baltic Sea climate has often been hampered by a lack of long, continuous, high-resolution climate records from this area. New high-resolution sediment cores collected by IODP/ECORD Expedition 347 (Baltic Sea Paleoenvironment) allow such records to be generated, including foraminiferal geochemistry records of Baltic Sea hydrographic conditions during the most recent deglaciation and early Holocene (~19-7 cal. ka). The dramatic changes in salinity, sea level, circulation, temperature, and oxygenation during this period, e.g. through massive meltwater release from proglacial lakes and the early Holocene inundation of the Baltic by seawater highlight these non-linear links between the Baltic and North Atlantic. This work uses benthic foraminiferal stable isotope records (δ18O and δ13C) from sites in the western Baltic (M0059, Lillebælt, early Holocene marine stage (Littorina Sea)) and Kattegat (M0060, Anholt, deglaciation) to constrain salinity changes during these intervals. Because of the dramatic changes in salinity this region experiences today and during the study periods, oxygen isotope records (δ18O) here primarily reflect a signal of changing salinity, with a reduced temperature effect. Early δ18O results from the western Baltic (M0059) show a trend of declining δ18O/salinity during the first several kyr of the Littorina Sea stage, in agreement with previous work indicating declining salinity due to gradual

  14. A stable isotopic perspective on orographic precipitation and continental evaporation in Turkey

    NASA Astrophysics Data System (ADS)

    Schemmel, F.; Mikes, T.; Mulch, A.; Rojay, B.

    2011-12-01

    One of the major tasks in terrestrial paleoclimate research is the reconstruction of continental precipitation changes and its effect on vegetation patterns as well as animal and human environments. Stable isotopes in precipitation have become increasingly important for characterizing various effects of surface uplift-related climate change and therefore allow us to investigate the relationship between climate and faunal and floral biodiversity over geological timescales. The central Anatolian plateau (Turkey) today -like its larger counterparts in Tibet and the Andes- creates a distinct rainfall pattern and reconstructing such patterns through geologic time is one of the major challenges for terrestrial paleoclimate research. With modern peak elevations of more than 3,000m the southern plateau margin (Taurus Mountains) must have played a pivotal role during surface uplift in controlling precipitation patterns within the plateau interior. Orographic precipitation along the plateau flanks subsequently impacts atmospheric moisture transport to regions further East including the near East and Central Asia. Here we present the first large-scale characterization of oxygen and hydrogen isotopes in precipitation and near-surface groundwaters including both, the northern (Pontide) and southern (Taurus mountains) plateau margins. The aim of this study is to quantify the modern effect of orographic rainout of the Taurus and Pontide Mountains on both δD and δ18O values as well as to provide insight into the combined effects of orographic rain out along the plateau margins and (evapo-)transpiration within the plateau interior. Two δD and δ18O sampling transects on the southern flank of the Taurus Mountains show similar trends with a systematic decrease of δD (-18 %/km) and δ18O (-2.7 %/km) with increasing elevation. Samples taken north of the Taurus range have significantly lower δD and δ18O values compared to samples along the Mediterranean coast. However, increasing

  15. Stable isotope customer list and summary of shipments:

    SciTech Connect

    Tracy, J.G.

    1988-03-01

    This compilation is published as an aid to those concerned with the separation and sale of stable isotopes. The information is divided into four sections: alphabetical lists of domestic and foreign customers;alphabetical lists of isotopes and services;alphabetical lists of states and countries;tabulation of the shipments, quantities, and dollars for each isotope and dollars for services divided into domestic, foreign, and DOE project categories. During FY 1987 sales of stable isotope products and services were made to 272 differnt customers, of whom 159 were domestic and 113 were foreign, representing 18 different foreign countries. The total revenue was $3,785,609 of which 12.3% was from sales to DOE project customers, 60.4% was from sales to other domestic customers, and 27.3% was from sales to foreign customers. this represented sales of 189 different stable isotopes plus associated services and was a 16.5% increase over FY 1986.

  16. From the Ground Up: Global Nitrous Oxide Sources are Constrained by Stable Isotope Values

    PubMed Central

    Snider, David M.; Venkiteswaran, Jason J.; Schiff, Sherry L.; Spoelstra, John

    2015-01-01

    Rising concentrations of nitrous oxide (N2O) in the atmosphere are causing widespread concern because this trace gas plays a key role in the destruction of stratospheric ozone and it is a strong greenhouse gas. The successful mitigation of N2O emissions requires a solid understanding of the relative importance of all N2O sources and sinks. Stable isotope ratio measurements (δ15N-N2O and δ18O-N2O), including the intramolecular distribution of 15N (site preference), are one way to track different sources if they are isotopically distinct. ‘Top-down’ isotope mass-balance studies have had limited success balancing the global N2O budget thus far because the isotopic signatures of soil, freshwater, and marine sources are poorly constrained and a comprehensive analysis of global N2O stable isotope measurements has not been done. Here we used a robust analysis of all available in situ measurements to define key global N2O sources. We showed that the marine source is isotopically distinct from soil and freshwater N2O (the continental source). Further, the global average source (sum of all natural and anthropogenic sources) is largely controlled by soils and freshwaters. These findings substantiate past modelling studies that relied on several assumptions about the global N2O cycle. Finally, a two-box-model and a Bayesian isotope mixing model revealed marine and continental N2O sources have relative contributions of 24–26% and 74–76% to the total, respectively. Further, the Bayesian modeling exercise indicated the N2O flux from freshwaters may be much larger than currently thought. PMID:25811179

  17. Multi-decadal carbon and water relations of African tropical humid forests: a tree-ring stable isotope analysis

    NASA Astrophysics Data System (ADS)

    Hufkens, K.; Beeckman, H.; de Haulleville, T.; Kearsley, E.; Toirambe, B.; Stoffelen, P.; Boeckx, P. F.

    2012-12-01

    Little is known about the temporal dynamics of the carbon sequestering capacity and dynamics of African tropical humid forest ecosystems in response to various environmental drivers. This lack of knowledge is mainly due to the absence of ecosystem scale flux measurements of gas exchange. However, tree growth often displays itself as alternating pattern of visible rings due to the varying growth speed of the vascular cambium. Consequently, analysis of tree growth through tree-ring analysis provides us with insights into past responses of the carbon sequestering capacity of key species to abrupt ecosystem disturbances and, while slower, a changing climate. Not only does the width and density of growth rings reflect annual growth but their isotopic composition of 13C and 18O isotopes also reveal the environmental conditions in which the trees were growing. In particular, stable isotope ratios in tree-rings of 13C are influenced by fractionation through carboxylation and changes in stomatal conductance. Similarly, fractionation of 18O from soil water occurs at the leaf level through evapo-transipiration. As a consequence, δ18O values in tree cores will reflect both the signal of the source water as well as that of for example summer humidity. Therefore, using both 13C and 18O stable isotopes might not only be valuable proxies of past climatic conditions but also serve as an important tool in understanding carbon and water relations within a forest ecosystems. To this end we correlate long term climate records (1961 - present) with tree ring measurement of incremental growth and high resolution analysis of tree-core stable isotope (13C / 18O) composition at two functionally similar, but geographically dissimilar, tropical humid forests in DR Congo. A first site, the Luki man and the biosphere (MAB) reserve, is located in the western part of DR Congo influenced by a tropical wet and dry climate. A second site, the Yangambi MAB reserve is located in the north

  18. Progress in Value Assignment for Stable Isotope Reference Materials

    NASA Astrophysics Data System (ADS)

    Gröning, M.; Taylor, P. D.; Klinedinst, D. B.

    2001-05-01

    A re-compilation of the existing certificate data for stable isotope reference materials was carried out at IAEA during the last years. Most of these isotopic ratios are expressed as per mil deviation relative to the isotopic ratio of an artificially chosen primary reference material using the commonly used conventional δ -scales. The recommended isotope values for those reference materials, produced by various researchers and institutions over the last four decades and distributed by the IAEA and NIST, have been subject to different `value assignment' approaches in the past and resulted in some inconsistencies in their recommended certified isotopic composition. During an IAEA Advisory Group meeting in September 2000 consensus was obtained on a consistent and robust a posteriori data evaluation to assign the value on the existing whole suite of stable isotope reference materials (RM) for the elements of hydrogen, carbon, nitrogen, oxygen and sulfur. Advances towards a closer calibration of carbon RMs were presented by NIST as a result of a performed calibration exercise for inorganic stable carbon RMs involving selected laboratories. For the first time sulfur stable isotope calibration data were presented by different institutions, which allow a firm and consistent value assignment of sulfur stable isotope RMs. At the same time efforts at IRMM were presented to tie up those conventional δ -scale values to SI-units by direct isotope ratio measurements using primary methods. The future challenges are twofold: 1. improving and maintaining the consistency of established stable isotope δ -scales by better characterization of existing reference materials and production of suitable successor materials (as example the primary water reference materials VSMOW and SLAP will be discussed), and 2. producing suitable reference materials for new analytical methods, especially in the field of organic compounds analyzed by means of continuous flow methods involving gas

  19. BIODEGRADATION OF FLUORANTHENE AS MONITORED USING STABLE CARBON ISOTOPES

    EPA Science Inventory

    The measurement of stable isotope ratios of carbon (d13C values) was investigated as a viable technique to monitor the intrinsic bioremediation of polycyclic aromatic hydrocarbons (PAHs). Biometer-flask experiments were conducted in which the bacterium, Sphingomonas paucimobilis,...

  20. High-Precision Tungsten Isotopic Analysis by Multicollection Negative Thermal Ionization Mass Spectrometry Based on Simultaneous Measurement of W and (18)O/(16)O Isotope Ratios for Accurate Fractionation Correction.

    PubMed

    Trinquier, Anne; Touboul, Mathieu; Walker, Richard J

    2016-02-01

    Determination of the (182)W/(184)W ratio to a precision of ± 5 ppm (2σ) is desirable for constraining the timing of core formation and other early planetary differentiation processes. However, WO3(-) analysis by negative thermal ionization mass spectrometry normally results in a residual correlation between the instrumental-mass-fractionation-corrected (182)W/(184)W and (183)W/(184)W ratios that is attributed to mass-dependent variability of O isotopes over the course of an analysis and between different analyses. A second-order correction using the (183)W/(184)W ratio relies on the assumption that this ratio is constant in nature. This may prove invalid, as has already been realized for other isotope systems. The present study utilizes simultaneous monitoring of the (18)O/(16)O and W isotope ratios to correct oxide interferences on a per-integration basis and thus avoid the need for a double normalization of W isotopes. After normalization of W isotope ratios to a pair of W isotopes, following the exponential law, no residual W-O isotope correlation is observed. However, there is a nonideal mass bias residual correlation between (182)W/(i)W and (183)W/(i)W with time. Without double normalization of W isotopes and on the basis of three or four duplicate analyses, the external reproducibility per session of (182)W/(184)W and (183)W/(184)W normalized to (186)W/(183)W is 5-6 ppm (2σ, 1-3 μg loads). The combined uncertainty per session is less than 4 ppm for (183)W/(184)W and less than 6 ppm for (182)W/(184)W (2σm) for loads between 3000 and 50 ng.

  1. Stable isotopes reveal sources of precipitation in the Qinghai Lake Basin of the northeastern Tibetan Plateau.

    PubMed

    Cui, Bu-Li; Li, Xiao-Yan

    2015-09-15

    The use of isotopic tracers is an effective approach for characterizing the moisture sources of precipitation in cold and arid regions, especially in the Tibetan Plateau (TP), an area of sparse human habitation with few weather and hydrological stations. This study investigated stable isotope characteristics of precipitation in the Qinghai Lake Basin, analyzed moisture sources using data sets from NCEP-NCAR, and calculated vapor contributions from lake evaporation to the precipitation in the basin using a two-component mixing model. Results showed that the Local Meteoric Water Line (LMWL) was defined as δ(2)H=7.86 δ(18)O+15.01, with a slope of less than 8, indicating that some non-equilibrium evaporation processes occurred when the drops fell below the cloud base. Temperature effects controlled δ(18)O and δ(2)H in precipitation in the basin, with high values in summer season and low values in winter season. Moisture in the basin was derived predominantly from the Southeast Asian Monsoon (SEAM) from June to August and the Westerly Circulation (WC) from September through May. Meanwhile, the transition in atmospheric circulation took place in June and September. The SEAM strengthened gradually, while the WC weakened gradually in June, and inversely in September. However, the Southwest Asian Monsoon (SWAM) did not reach the Qinghai Lake Basin due to the barrier posed by Tanggula Mountain. High d-excess (>10 ‰) and significant altitude and lake effects of δ(18)O in precipitation suggested that the vapor evaporated from Qinghai Lake, strongly influenced annual precipitation, and affected the regional water cycle in the basin distinctly. The monthly contribution of lake evaporation to basin precipitation ranged from 3.03% to 37.93%, with an annual contribution of 23.42% or 90.54 mm, the majority of which occurred in the summer season. The findings demonstrate that the contribution of evaporation from lakes to atmospheric vapor is fundamental to water cycling on the

  2. Clumped Isotopes, trace elements, and δ18O of stromatolites from the Laney Member of the Green River Formation (Eocene): Implications for paleoenvironments during the Eocene Climatic Optimum

    NASA Astrophysics Data System (ADS)

    Corsetti, F. A.; Miller, H. M.; Asangba, A. E.; Johannessen, K. C.; Wang, D. T.; Petryshyn, V. A.; Tripati, A.; Shapiro, R. S.

    2013-12-01

    The Green River Formation, a large lacustrine deposit located across parts of Utah, Colorado, and Wyoming, was deposited during the Eocene Climatic Optimum (~50 Ma), a period of sustained high temperatures and high atmospheric CO2 levels that may provide a geologic analog for future climate scenarios. Large variations in basin hydrology, water chemistry, and paleotemperatures occurring on time scales of tens of thousands of years or longer have been documented in the sedimentary record. Here, we use stromatolites to investigate much finer-scale resolution of paleoenvironmental changes in the Green River Formation and paleo-Lake Gosiute. We studied the lower LaClede Bed, the base of the Laney Member of the Green River Formation, comprised of cyclic layers of oil shale and carbonate. The lower LaClede Bed represents the filling of the lake following an extended period of closure during deposition of the underlying Wilkins Peak Member. To characterize fluctuations in water chemistry and lake level at greater temporal resolution, we conducted micro-stratigraphic and chemostratigraphic analyses on 24 distinct mm-scale laminae in a single 10 cm carbonate stromatolite bed, including δ13C, δ18O, and trace elemental analyses (Mg, Mn, Fe, Si, K, Na, Al, Sr). Sub-cm-scale correlations between petrographic analyses, elemental composition, and carbonate δ13C and δ18O suggest that this stromatolite records both hydrologically-closed and -open periods in the history of Lake Gosiute. During periods of apparent basin closure, we used two models to investigate lake volume change: 1) a Rayleigh distillation model of water evaporation to estimate lake depth variations and 2) a conservative ion model based on Na incorporation into the stromatolites. In both models, lake depth fluctuated by up to 8 m; this represents up to 40km of shoreline change in Lake Gosiute during the deposition of this stromatolite layer. Interestingly, the modern Great Salt Lake experienced similar

  3. Oxygen isotopes in synthetic goethite and a model for the apparent pH dependence of goethite-water 18O/ 16O fractionation

    NASA Astrophysics Data System (ADS)

    Yapp, Crayton J.

    2007-03-01

    Goethite synthesis experiments indicate that, in addition to temperature, pH can affect the measured value of the 18O/ 16O fractionation factor between goethite and water ( αG-W). A simple model was developed which expresses αG-W in terms of kinetic parameters associated with the growth of goethite from aqueous solution. The model predicts that, at a particular temperature, the range of pH over which αG-W changes as pH changes is expected to be comparatively small (˜3 pH "units") relative to the range of pH values over which goethite can crystallize (pH from ˜1 to 14). Outside the range of sensitivity to pH, αG-W is predicted to be effectively constant (for constant temperature) at either a low-pH αG-W value or a high-pH αG-W value. It also indicates that the values of αG-W at high pH will be disequilibrium values. Values of αG-W for goethite crystallized at low pH may approach, but probably do not attain, equilibrium values. For goethite synthesized at values of pH from ˜1 to 2, data from two different laboratories define the following equation for the temperature dependence of 1000 ln αG-W ( T in degrees Kelvin) 1000lnα={1.66×106}/{T2}-12.6 Over the range of temperatures from 0 to 120°C, values of 1000 ln αG-W from Eq. (IV) differ by ⩽0.1‰from those of a published equation [Yapp C.J., 1990. Oxygen isotopes in iron (III) oxides. 1. Mineral-water fractionation factors. Chem. Geol.85, 329-335]. Therefore, interpretations of data from natural goethites using the older equation are not changed by use of Eq. (IV). Data from a synthetic goethite suggest that the temperature dependence of 1000 ln αG-W at low pH as expressed in Eq. (IV) may be valid for values of pH up to at least 6. This result and the model prediction of an insensitivity of αG-W to pH over a larger range of pH values could explain the observation that Eq. (IV) yields values of αG-W which mimic most 18O/ 16O fractionations measured to date in natural goethites.

  4. Chlorine stable isotopes in sedimentary systems: does size matter?

    NASA Technical Reports Server (NTRS)

    Coleman, Max

    2004-01-01

    Stable isotope abundances vary because of size differences. The chlorine stable isotope system was one of the first described theoretically, but had a slow, disappointment strewn development, relative to other elements. Method improvement gave only small, but significant, differences in compositions of geological materials. Eventually, brines and groundwater chlorides gave larger differences. Physical processes like diffusion and adsorption, probably are the main controls of groundwater compositions. Recent work on anthropogenic groundwater contaminants shows variations resulting from manufacturing processes; implying possibilities of tracing sources.

  5. Stable isotope sales: Mound customer and shipment summaries, FY 1988

    SciTech Connect

    Flayler, K.A.

    1990-04-23

    This report lists Mound's sales of stable isotopes of noble gases, carbon, oxygen, nitrogen, chlorine, bromine, and sulfur for fiscal year 1988. Purchasers are listed alphabetically and are divided into domestic and foreign groups. Cross-reference indexes by location and by isotope purchases are included for all customers. 3 tabs.

  6. USE OF STABLE ISOTOPES IN ENVIRONMENTAL AND FORENSIC GEOCHEMISTRY STUDIES

    EPA Science Inventory

    Stable carbon and hydrogen isotopes have been used for many decades in the petroleum industry, but the development of combined gas chromatography-isotope ratio mass spectrometry (GCIRMS) has led to a virtual explosion in application of this technique not only in petroleum explora...

  7. Stable Isotope Tracers of Process in Great Lakes Food Webs

    EPA Science Inventory

    Stable isotope analyses of biota are now commonly used to discern trophic pathways between consumers and their foods. However, those same isotope data also hold information about processes that influence the physicochemical setting of food webs as well as biological processes ope...

  8. ESTIMATING THE TIMING OF DIET SHIFTS USING STABLE ISOTOPES

    EPA Science Inventory

    Stable isotope analysis has become an important tool in studies of trophic food webs and animal feeding patterns. When animals undergo rapid dietary shifts due to migration, metamorphosis, or other reasons, the isotopic composition of their tissues begins changing to reflect tha...

  9. Carbon Stable Isotopes as Indicators of Coastal Eutrophication

    EPA Science Inventory

    Coastal ecologists and managers have frequently used nitrogen stable isotopes (δ15N) to trace and monitor anthropogenic nitrogen (N) in coastal ecosystems. However, the interpretation of δ15N data can often be challenging, if not confounding, as the isotope values fractionate su...

  10. SOURCE PARTITIONING USING STABLE ISOTOPES: COPING WITH TOO MANY SOURCES

    EPA Science Inventory

    Stable isotopes are increasingly being used as tracers in environmental studies. One application is to use isotopic ratios to quantitatively determine the proportional contribution of several sources to a mixture, such as the proportion of various pollution sources in a waste st...

  11. Stable isotope sales: Mound customer and shipment summaries, FY 1986

    SciTech Connect

    Kramer, L.R.; Flayler, K.A.

    1988-05-20

    A listing is given of Mound's sales of stable isotopes of noble gases, carbon, oxygen, nitrogen, chlorine, and sulfur for fiscal year 1986. Purchasers are listed alphabetically and are divided into domestic and foreign groups. Cross-reference indexes by location and by isotope are included for all customers. 3 tabs.

  12. Stable isotopes sales: Mound customer and shipment summaries, FY 1985

    SciTech Connect

    Flayler, K.A.

    1987-12-15

    A listing is given of Mound's sales of stable isotopes of noble gases, deuterium, carbon, oxygen, nitrogen, chlorine, bromine, and sulfur for fiscal year 1985. Purchasers are listed alphabetically and are divided into domestic and foreign groups. A cross-reference index by location is included for domestic and foreign customers. Cross-reference listings by isotope purchased are included for all customers.

  13. Stable isotope record of coexisting apatite and dolomite in Early Cambrian phosphorites, Meishucun section, South China

    NASA Astrophysics Data System (ADS)

    Wegwerth, Antje; Struck, Ulrich; Segl, Monika; Vennemann, Torsten W.; Gehlken, Peer-L.; Heubeck, Christoph; Böttcher, Michael E.

    2010-05-01

    The Precambrian-Cambrian transition forms one of the most dramatic time periods in Earth's history, as global changes in tectonics, climate and chemistry in the atmosphere and oceans favoured the worldwide Cambrian Radiation and a concomitant ecosphere revolution. This time interval is paralleled by the first appearance of the widespread giant phosphorites. The well-known Meishucun section (South China), a former candidate section for the Pc-C boundary, documents phosphorite genesis amongst a rapid biodiversification, immediately following the end of the Precambrian in a low-latitude, shallow-water carbonate shelf. This contribution aims to elucidate the relation between simultaneous phosphorite deposition and global environmental conditions at the Pc-C boundary by using stable carbon and oxygen isotope analyses. Accurate determinations of d13C and d18O values may allow conclusions about ancient ocean circulation, paleo-productivity, paleo-temperatures, and most prominently diagenetic processes. The investigated samples from the Meishucun section basically consist of apatite, dolomite, and quartz that may be further devided into a lower and upper phosphorite as well as an overlying dolostone intervall. Additionally, calcite and siderite occur as minor compounds in some samples. Bulk d13C values of the carbonate fraction correlate with dolomite abundance throughout the section ranging from -4 to 1 per mil. Furthermore, several horizons suggest a relation between d13C values and apatite content, implying lower d13C values in apatites compared to coexisting dolomite. A slight negative d13C excursion at the top of the lower phosphorite coincides with the first appearance of small shelly fossils. Corresponding bulk d18O values generally show a stratigraphic-upward trend towards lower values throughout the record with slightly higher values in dolomite-rich sections. This may either indicate a warming trend during deposition, an isotopic shift in sea water composition

  14. Metal stable isotopes in weathering and hydrology: Chapter 10

    USGS Publications Warehouse

    Bullen, Thomas D.; Holland, Heinrich; Turekian, K.

    2014-01-01

    This chapter highlights some of the major developments in the understanding of the causes of metal stable isotope compositional variability in and isotope fractionation between natural materials and provides numerous examples of how that understanding is providing new insights into weathering and hydrology. At this stage, our knowledge of causes of stable isotope compositional variability among natural materials is greatest for the metals lithium, magnesium, calcium, and iron, the isotopes of which have already provided important information on weathering and hydrological processes. Stable isotope compositional variability for other metals such as strontium, copper, zinc, chromium, barium, molybdenum, mercury, cadmium, and nickel has been demonstrated but is only beginning to be applied to questions related to weathering and hydrology, and several research groups are currently exploring the potential. And then there are other metals such as titanium, vanadium, rhenium, and tungsten that have yet to be explored for variability of stable isotope composition in natural materials, but which may hold untold surprises in their utility. This impressive list of metals having either demonstrated or potential stable isotope signals that could be used to address important unsolved questions related to weathering and hydrology, constitutes a powerful toolbox that will be increasingly utilized in the coming decades.

  15. Stable and Radiogenic Isotope Evidence Relating to Regional Groundwater Flow Ssystems Originating in the High Sacramento Mountains, New Mexico

    NASA Astrophysics Data System (ADS)

    Eastoe, C. J.; Hibbs, B. J.

    2005-12-01

    Groundwater from the Sacramento Mountains and adjacent basin-fill sediments near Tularosa and Alamogordo has values of δ D , δ18O that plot in δ D vs. δ18O space on a linear trend of slope 5. Tritium is detectable in most samples. Carbon-14 content generally decreases downgradient from 80-90 pMC in the high mountains to 20-40 pMC in basin fill. Precipitation from areas above 2000 m elevation is the dominant water source. The O and H stable isotope data are best explained by mixing of non-evaporated water transmitted slowly through rock fractures with evaporated water of the same source transmitted rapidly as runoff to the point of recharge. Evaporation of surface water occurs from canyon-bottom sediment. Sacramento Mountains water replenishes the Tularosa basin aquifer by a combination of mountain-front and mountain-block recharge. It also replenishes a limestone-hosted aquifer extending 100 km southeast of Cloudcroft, New Mexico. Groundwater in basin fill at Dell City, Texas appears to have distinctive values of δ D, δ18O that are better explained by recharge of precipitation from high areas of the Diablo Plateau. Regional groundwater flow from the Sacramento Mountains to the Hueco Bolson aquifer is likely; however, O and H stable isotope data do not distinguish Sacramento Mountains water from other inputs to the Hueco Bolson.

  16. Reliability of stable carbon and oxygen isotope compositions of pedogenic needle fibre calcite as environmental indicators: examples from Western Europe.

    PubMed

    Millière, Laure; Spangenberg, Jorge E; Bindschedler, Saskia; Cailleau, Guillaume; Verrecchia, Eric P

    2011-09-01

    Stable carbon and oxygen isotope analyses were conducted on pedogenic needle fibre calcite (NFC) from seven sites in areas with roughly similar temperate climates in Western Europe, including the Swiss Jura Mountains, eastern and southern France, northern Wales, and north-eastern Spain. The δ(13)C values (-12.5 to-6.8 ‰ Vienna Pee Dee Belemnite (VPDB)) record the predominant C(3) vegetation cover at the sites. A good correlation was found between mean monthly climatic parameters (air temperature, number of frost days, humidity, and precipitation) and δ(18)O values (-7.8 to-3.4‰ VPDB) of all the NFC. Similar seasonal variations of δ(18)O values for monthly NFC samples from the Swiss sites and those of mean monthly δ(18)O values of local precipitation and meteorological data point out precipitation and preferential growth/or recrystallisation of the pedogenic needle calcite during dry seasons. These covariations indicate the potential of stable isotope compositions of preserved NFC in fossil soil horizons as a promising tool for palaeoenvironmental reconstructions.

  17. Temporal variation of oxygen isotope ratios (δ