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Sample records for 18o stable isotope

  1. 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.

  2. Stable isotope variations (δ18O and δD) in modern waters across the Andean Plateau

    NASA Astrophysics Data System (ADS)

    Bershaw, John; Saylor, Joel E.; Garzione, Carmala N.; Leier, Andrew; Sundell, Kurt E.

    2016-12-01

    Environmental parameters that influence the isotopic composition of meteoric water (δ18O and δD) are well characterized up the windward side of mountains, where orographic precipitation results in a predictable relationship between the isotopic composition of precipitation and elevation. The topographic and climatic evolution of the Andean Plateau and surrounding regions has been studied extensively by exploiting this relationship through the use of paleowater proxies. However, interpretation on the plateau itself is challenged by a poor understanding of processes that fractionate isotopes during vapor transport and rainout, and by the relative contribution of unique moisture sources. Here, we present an extensive dataset of modern surface water samples for the northern Andean Plateau and surrounding regions to elucidate patterns and causes of isotope fractionation in this continental environment. These data show a progressive increase in δ18O of stream water west of the Eastern Cordillera (∼1‰/70 km), almost identical to the rate observed across the Tibetan Plateau, attributed to a larger fraction of recycled water in precipitation and/or increased evaporative enrichment downwind. This may lead to underestimates of paleoelevation, particularly for sites deep into the rainshadow of the Eastern Cordilleran crest. That said, elevation is a primary control on the isotopic composition of surface waters across the entire Andean Plateau and its flanks when considering the most negative δ18O values, highlighting the need for sufficiently large datasets to distinguish minimally evaporated samples. There is a general increase in δ18O on the plateau from north to south, concomitant with an increase in aridity and decrease in convective moistening (amount effect). Lastly, stable isotope and seasonal precipitation patterns suggest easterlies provide the vast majority of moisture that falls as precipitation across the Andean Plateau and Western Cordillera, from Peru to

  3. 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.

  4. 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

  5. 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

  6. 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

  7. 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. 

  8. 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.

  9. 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.

  10. Correction algorithm for online continuous flow δ13C and δ18O carbonate and cellulose stable isotope analyses

    NASA Astrophysics Data System (ADS)

    Evans, M. N.; Selmer, K. J.; Breeden, B. T.; Lopatka, A. S.; Plummer, R. E.

    2016-09-01

    We describe an algorithm to correct for scale compression, runtime drift, and amplitude effects in carbonate and cellulose oxygen and carbon isotopic analyses made on two online continuous flow isotope ratio mass spectrometry (CF-IRMS) systems using gas chromatographic (GC) separation. We validate the algorithm by correcting measurements of samples of known isotopic composition which are not used to estimate the corrections. For carbonate δ13C (δ18O) data, median precision of validation estimates for two reference materials and two calibrated working standards is 0.05‰ (0.07‰); median bias is 0.04‰ (0.02‰) over a range of 49.2‰ (24.3‰). For α-cellulose δ13C (δ18O) data, median precision of validation estimates for one reference material and five working standards is 0.11‰ (0.27‰); median bias is 0.13‰ (-0.10‰) over a range of 16.1‰ (19.1‰). These results are within the 5th-95th percentile range of subsequent routine runtime validation exercises in which one working standard is used to calibrate the other. Analysis of the relative importance of correction steps suggests that drift and scale-compression corrections are most reliable and valuable. If validation precisions are not already small, routine cross-validated precision estimates are improved by up to 50% (80%). The results suggest that correction for systematic error may enable these particular CF-IRMS systems to produce δ13C and δ18O carbonate and cellulose isotopic analyses with higher validated precision, accuracy, and throughput than is typically reported for these systems. The correction scheme may be used in support of replication-intensive research projects in paleoclimatology and other data-intensive applications within the geosciences.

  11. 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).

  12. 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

  13. 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.

  14. 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

  15. 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

  16. 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.

  17. 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.

  18. Groundwater discharge and hydrologic partition of the lakes in desert environment: Insights from stable 18O/2H and radium isotopes

    NASA Astrophysics Data System (ADS)

    Luo, Xin; Jiao, Jiu Jimmy; Wang, Xu-sheng; Liu, Kun; Lian, Ergang; Yang, Shouye

    2017-03-01

    Studies of isotope characteristics of lake water in a desert can provide important information on groundwater discharge and hydrologic partition of the lakes in the desert. This paper presents the investigation of 18O and 2H stable isotopes and radiogenic radium of different water endmembers in three representative lakes of Badain-E, Badain-W and Sumujilin-S in the Badain Jaran Desert (BJD), the fourth largest desert in the world. A stable 18O and 2H isotopic buildup model is constructed to classify the hydrologic conditions of the desert lakes by estimating the ratio between groundwater discharge rate (Fin) and lake surface evaporation (E). Then the radium mass balance models are developed to quantify Fin. Based on the obtained Fin/E and Fin, Badain-E, Badain-W and Sumujilin-S are classified as flowing through, terminal and desiccating lakes, respectively, and their hydrologic partition is obtained. The groundwater discharge rate of Badain-E, Badain-W and Sumujilin-S, is estimated to be 8-10 mm d-1, 4-5 mm d-1, and 7-8 mm d-1, respectively. The total groundwater discharge to the lake areas in the BJD is about 1.68 × 105 m3 d-1. The flow-through condition explains the existence of the fresh lakes, while the terminal and desiccating conditions lead to the lake salinization over time. This study represents the first attempt to couple both stable and radium isotopic approaches to investigate the groundwater discharge and hydrologic partition of desert lakes in the BJD and is instructional to lake studies in other deserts in the world.

  19. Experimental assessment of the purity of α-cellulose produced by variations of the Brendel method: Implications for stable isotope (δ13C, δ18O) dendroclimatology

    NASA Astrophysics Data System (ADS)

    Brookman, Tom; Whittaker, Thomas

    2012-09-01

    Stable isotope dendroclimatology using α-cellulose has unique potential to deliver multimillennial-scale, sub-annually resolved, terrestrial climate records. However, lengthy processing and analytical methods often preclude such reconstructions. Variants of the Brendel extraction method have reduced these limitations, providing fast, easy methods of isolating α-cellulose in some species. Here, we investigate application of Standard Brendel (SBrendel) variants to resinous soft-woods by treating samples of kauri (Agathis australis), ponderosa pine (Pinus ponderosa) and huon pine (Lagarastrobus franklinii), varying reaction vessel, temperature, boiling time and reagent volume. Numerous samples were visibly `under-processed' and Fourier Transform infrared spectroscopic (FTIR) investigation showed absorption peaks at 1520 cm-1 and ˜1600 cm-1 in those fibers suggesting residual lignin and retained resin respectively. Replicate analyses of all samples processed at high temperature yielded consistent δ13C and δ18O despite color and spectral variations. Spectra and isotopic data revealed that α-cellulose δ13C can be altered during processing, most likely due to chemical contamination from insufficient acetone removal, but is not systematically affected by methodological variation. Reagent amount, temperature and extraction time all influence δ18O, however, and our results demonstrate that different species may require different processing methods. FTIR prior to isotopic analysis is a fast and cost effective way to determine α-cellulose extract purity. Furthermore, a systematic isotopic test such as we present here can also determine sensitivity of isotopic values to methodological variables. Without these tests, isotopic variability introduced by the method could obscure or `create' climatic signals within a data set.

  20. Investigating the influence of sulphur dioxide (SO 2) on the stable isotope ratios (δ 13C and δ 18O) of tree rings

    NASA Astrophysics Data System (ADS)

    Rinne, K. T.; Loader, N. J.; Switsur, V. R.; Treydte, K. S.; Waterhouse, J. S.

    2010-04-01

    This study reports the influence of a 20th century pollution signal recorded in the δ 13C and δ 18O of absolutely dated tree rings from Quercus robur and Pinus sylvestris from southern England. We identify a correspondence between the inter-relationship and climate sensitivity of stable isotope series that appears to be linked to recent trends in local SO 2 emissions. This effect is most clearly exhibited in the broadleaved trees studied but is also observed in the δ 13C values of the (less polluted) pine site at Windsor. The SO 2 induced stomatal closure leads to a maximum increase of 2.5‰ in the isotope values (δ 13C). The combined physiological response to high pollution levels is less in δ 18O than δ 13C. The SO 2 signal also seems to be present as a period of reduced growth in the two ring-width chronologies. Direct, quantitative correction for the SO 2 effect represents a significant challenge owing to the nature of the records and likely local plant response to environmental pollution. Whilst it appears that this signal is both limited to the late industrial period and demonstrates a recovery in line with improvements in air quality, the role of atmospheric pollution during the calibration period should not be underestimated and adequate consideration needs to be taken when calibrating biological environmental proxies in order to avoid development of biased reconstructions.

  1. Measurements of 18O18O and 17O18O in the atmosphere and the role of isotope-exchange reactions

    NASA Astrophysics Data System (ADS)

    Yeung, Laurence Y.; Young, Edward D.; Schauble, Edwin A.

    2012-09-01

    Of the six stable isotopic variants of O2, only three are measured routinely. Observations of natural variations in 16O18O/16O16O and 16O17O/16O16O ratios have led to insights in atmospheric, oceanographic, and paleoclimate research. Complementary measurements of the exceedingly rare 18O18O and 17O18O isotopic variants might therefore broaden our understanding of oxygen cycling. Here we describe a method to measure natural variations in these multiply substituted isotopologues of O2. Its accuracy is demonstrated by measuring isotopic effects for Knudsen diffusion and O2 electrolysis in the laboratory that are consistent with theoretical predictions. We then report the first measurements of 18O18O and 17O18O proportions relative to the stochastic distribution of isotopes (i.e., Δ36 and Δ35 values, respectively) in tropospheric air. Measured enrichments in 18O18O and 17O18O yield Δ36 = 2.05 ± 0.24‰ and Δ35 = 1.4 ± 0.5‰ (2σ). Based on the results of our electrolysis experiment, we suggest that autocatalytic O(3P) + O2 isotope exchange reactions play an important role in regulating the distribution of 18O18O and 17O18O in air. We constructed a box model of the atmosphere and biosphere that includes the effects of these isotope exchange reactions, and we find that the biosphere exerts only a minor influence on atmospheric Δ36 and Δ35 values. O(3P) + O2 isotope exchange in the stratosphere and troposphere is therefore expected to govern atmospheric Δ36 and Δ35 values on decadal timescales. These results suggest that the `clumped' isotopic composition of atmospheric O2in ice core records is sensitive to past variations in atmospheric dynamics and free-radical chemistry.

  2. 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.

  3. 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.

  4. 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.

  5. 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.

  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. 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

  8. 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.

  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. 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.

  11. 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

  12. 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

  13. 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

  14. Simultaneous determination of stable isotopic compositions of nitrous oxide (δ15N and δ18O of N2O) and methane (δ13C of CH4) in nanomolar quantities from a single water sample

    NASA Astrophysics Data System (ADS)

    Hirota, A.; Tsunogai, U.; Komatsu, D. D.; Nakagawa, F.

    2010-12-01

    The stable isotopic compositions of nitrous oxide (δ15N of N2O and δ18O of N2O, respectively) and methane (δ13C of CH4) have provided us with some interesting geochemical insights. We have developed a rapid, sensitive, and automated analytical system to simultaneously determine the concentrations and stable isotopic compositions of nanomolar quantities of N2O and CH4 in the environmental water, by combining continuous-flow isotope-ratio mass spectrometry and a He-sparging system to extract and purify the dissolved gases. Our system, which is composed of a sparging bottle, a chemical trap, four cold traps and a capillary gas chromatograph that use ultra-pure helium as the carrier gas, achieves complete extraction of N2O and CH4 in a water sample and separation among N2O, CH4, and the other component gases. The flow path subsequent to gas chromatograph was periodically changed to pass the gases through the combustion furnace to convert CH4 and the other hydrocarbons into CO2, or to bypass the combustion furnace for the direct introduction of eluted N2O into the mass spectrometer, for determining the stable isotopic compositions through monitoring m/z = 44, 45, and 46, on the bases of CO2+ and N2O+, respectively. The analytical system can be operated automatically with sequential software programmed on a personal computer. The analytical precisions (the standard deviation of a single measurement) were better than 0.2‰ for δ15N of N2O and 0.3‰ for δ18O of N2O, in the case of more than 6.7 nmol N2O injection and better than 1.4‰ for δ15N of N2O and 2.6‰ for δ18O of N2O, in the case of more than 0.2 nmol N2O injection, respectively. Simultaneously, the analytical precisions were better than 0.07‰ for δ13C of CH4, in the case of more than 5.5 nmol CH4 infection and better than 2.1‰ for δ13C of CH4, when more than 0.024 nmol CH4 injection. In this manner, we can simultaneously determine stable isotopic compositions of a 120 mL water sample having

  15. 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.

  16. An extractive removal step optimized for a high-throughput α-cellulose extraction method for δ13C and δ18O stable isotope ratio analysis in conifer tree rings.

    PubMed

    Lin, Wen; Noormets, Asko; King, John S; Sun, Ge; McNulty, Steve; Domec, Jean-Christophe

    2016-09-26

    Stable isotope ratios (δ(13)C and δ(18)O) of tree-ring α-cellulose are important tools in paleoclimatology, ecology, plant physiology and genetics. The Multiple Sample Isolation System for Solids (MSISS) was a major advance in the tree-ring α-cellulose extraction methods, offering greater throughput and reduced labor input compared to traditional alternatives. However, the usability of the method for resinous conifer species may be limited by the need to remove extractives from some conifer species in a separate pretreatment step. Here we test the necessity of pretreatment for α-cellulose extraction in loblolly pine (Pinus taeda L.), and the efficiency of a modified acetone-based ambient-temperature step for the removal of extractives (i) in loblolly pine from five geographic locations representing its natural range in the southeastern USA, and (ii) on five other common coniferous species (black spruce (Picea mariana Mill.), Fraser fir (Abies fraseri (Pursh) Poir.), Douglas fir (Pseudotsuga menziesii (Mirb.) Franco), Norway spruce (Picea abies (L.) Karst) and ponderosa pine (Pinus ponderosa D.)) with contrasting extractive profiles. The differences of δ(13)C values between the new and traditional pretreatment methods were within the precision of the isotope ratio mass spectrometry method used (±0.2‰), and the differences between δ(18)O values were not statistically significant. Although some unanticipated results were observed in Fraser fir, the new ambient-temperature technique was deemed as effective as the more labor-consuming and toxic traditional pretreatment protocol. The proposed technique requires a separate acetone-inert multiport system similar to MSISS, and the execution of both pretreatment and main extraction steps allows for simultaneous treatment of up to several hundred microsamples from resinous softwood, while the need of additional labor input remains minimal.

  17. 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

  18. Quantitative Microbial Ecology through Stable Isotope Probing

    PubMed Central

    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.

    2015-01-01

    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 18O and 13C composition after exposure to [18O]water or [13C]glucose. The addition of glucose increased the assimilation of 18O into DNA from [18O]water. However, the increase in 18O 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. PMID:26296731

  19. 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.

  20. Stable isotopic compositions in Australian precipitation

    NASA Astrophysics Data System (ADS)

    Liu, Jianrong; Fu, Guobin; Song, Xianfang; Charles, Stephen P.; Zhang, Yinghua; Han, Dongmei; Wang, Shiqin

    2010-12-01

    Stable deuterium (δD) and oxygen-18 (δ18O) isotopes in 1962 to 2002 precipitation from the seven Australian stations of the Global Network of Isotopes in Precipitation (GNIP) were used to investigate isotope characteristics including temporal and spatial distributions across different regions of Australia. On the basis of 1534 samples, the local meteoric water line (LMWL) was established as δD = 7.10δ18O + 8.21. δ18O showed a depletion trend from north and south to central Australia (a continental effect) and from west to east. Precipitation amount effects were generally greater than temperature effects, with quadratic or logarithmic correlations describing δ/T and δ/P better than linear relationships. Nonlinear stepwise regression was used to determine the significant meteorological control factors for each station, explaining about 50% or more of the δ18O variations. Geographical control factors for δ18O were given by the relationship δ18O (‰) = -0.005 longitude (°) - 0.034 latitude (°)-0.003 altitude (m) - 4.753. Four different types of d-excess patterns demonstrated particular precipitation formation conditions for four major seasonal rainfall zones. Finally, wavelet coherence (WTC) between δ18O and SOI confirmed that the influence of ENSO decreased from east and north to west Australia.

  1. 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

  2. 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.

  3. Isotope 18 O 16 O Ratio Measurements of Water Vapor by use of Photoacoustic Spectroscopy

    NASA Astrophysics Data System (ADS)

    Matsumi, Yutaka; Kishigami, Masahiro; Tanaka, Noriyuki; Kawasaki, Masahiro; Inoue, Gen

    1998-09-01

    We applied a photoacoustic spectroscopy technique to isotope ratio measurements of 16 O and 18 O in water-vapor samples, using a pulsed tunable dye laser pumped by a Nd:YAG laser. The fourth overtone bands (4 OH ) of water molecules near 720 nm were investigated. We identified the absorption lines of H 2 16 O and H 2 18 O in the photoacoustic spectra that we measured by using an 18 O-enriched water sample and the HITRAN database. We measured the difference in the 18 O 16 O isotope ratios for normal distilled water and Antarctic ice, using the photoacoustic method. The value obtained for the difference between the two samples is 18 O 32 16 , where the indicated deviation was a 1 value among 240-s measurements, whereas the value measured with a conventional isotope mass spectrometer was 18 O 28 2 . This method is demonstrated to have the potential of a transportable system for in situ and quick measurements of the H 2 18 O H 2 16 O ratio in the environment.

  4. 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.

  5. 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.

  6. Isotope parameters (δD, δ18O) and sources of freshwater input to Kara Sea

    NASA Astrophysics Data System (ADS)

    Dubinina, E. O.; Kossova, S. A.; Miroshnikov, A. Yu.; Fyaizullina, R. V.

    2017-01-01

    The isotope characteristics (δD, δ18O) of Kara Sea water were studied for quantitative estimation of freshwater runoff at stations located along transect from Yamal Peninsula to Blagopoluchiya Bay (Novaya Zemlya). Freshwater samples were studied for glaciers (Rose, Serp i Molot) and for Yenisei and Ob estuaries. As a whole, δD and δ18O are higher in glaciers than in river waters. isotope composition of estuarial water from Ob River is δD =-131.4 and δ18O =-17.6‰. Estuarial waters of Yenisei River are characterized by compositions close to those of Ob River (-134.4 and-17.7‰), as well as by isotopically "heavier" compositions (-120.7 and-15.8‰). Waters from studied section of Kara Sea can be product of mixing of freshwater (δD =-119.4, δ18O =-15.5) and seawater (S = 34.9, δD = +1.56, δ18O = +0.25) with a composition close to that of Barents Sea water. isotope parameters of water vary significantly with salinity in surface layer, and Kara Sea waters are desalinated along entire studied transect due to river runoff. concentration of freshwater is 5-10% in main part of water column, and <5% at a depth of >100 m. maximum contribution of freshwater (>65%) was recorded in surface layer of central part of sea.

  7. 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.

  8. 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.

  9. 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.

  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 -1.1 ± 1

  11. Larix decidua δ(18)O tree-ring cellulose mainly reflects the isotopic signature of winter snow in a high-altitude glacial valley of the European Alps.

    PubMed

    Leonelli, Giovanni; Battipaglia, Giovanna; Cherubini, Paolo; Saurer, Matthias; Siegwolf, Rolf T W; Maugeri, Maurizio; Stenni, Barbara; Fusco, Stella; Maggi, Valter; Pelfini, Manuela

    2017-02-01

    We analyzed the chronologies of cellulose stable isotopes (δ(13)C and δ(18)O) and tree-ring widths from European larch (Larix decidua) in a high-altitude site (2190ma.s.l.) at the bottom of a glacial valley in the Italian Alps, and investigated their dependence on monthly meteorological variables and δ(18)O precipitation values. The δ(18)O of tree-ring cellulose appears to be strongly driven by the δ(18)O of winter snowfall (November to March), which suggests that larch trees mostly use the snow-melt water of the previous winter during the growing season. This water, which also comes from the slope streams and from the underground flow of nearby steep slopes, infiltrates the soil in the valley bottom. The tree-ring cellulose δ(18)O values were also found to be influenced by the August precipitation δ(18)O and mean temperature. The associated regression model shows that the δ(18)O chronology from the tree rings explains up to 34% of the variance in the winter precipitation δ(18)O record, demonstrating the potential for reconstructing the δ(18)O isotopic composition of past winter precipitation in the study region. Unlike most other tree-ring studies that focus on growing season signals, in our study the summer signal was small and the winter signal dominant due to the special conditions of the glacial valley. Site topography, geomorphology and soil characteristics in particular influence the stable isotope signal in tree-ring cellulose.

  12. 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.

  13. Synthesis on evaporation partitioning using stable isotopes

    NASA Astrophysics Data System (ADS)

    Coenders-Gerrits, Miriam; Bogaard, Thom; Wenninger, Jochen; Jonson Sutanto, Samuel

    2015-04-01

    Partitioning of evaporation into productive (transpiration) and non-productive evaporation (interception, soil evaporation) is of highest importance for water management practices, irrigation scheme design, and climate modeling. Despite this urge, the magnitude of the ratio of transpiration over total evaporation is still under debate and poorly understood due to measuring difficulties. However, with the current development in isotope measuring devices, new opportunities arise to untangle the partitioning of evaporation. In this paper we synthesize the opportunities and limitations using stable water isotopes in evaporation partitioning. We will analyze a set of field as well as laboratory studies to demonstrate the different evaporation components for various climate and vegetation conditions using stable isotopes 18O/16O and 2H/1H. Experimental data on evaporation partitioning of crops, grass, shrubs and trees are presented and we will discuss the specific experimental set-ups and data collection methods. The paper will be a synthesis of these studies.

  14. Elemental and isotopic ( 29Si and 18O) tracing of glass alteration mechanisms

    NASA Astrophysics Data System (ADS)

    Valle, Nathalie; Verney-Carron, Aurélie; Sterpenich, Jérôme; Libourel, Guy; Deloule, Etienne; Jollivet, Patrick

    2010-06-01

    To better understand glass alteration mechanisms, especially alteration layers formation, leaching experiments of a borosilicate glass (SON68) doped with a different rare earth element (La, Ce, or Nd) with solutions rich in 29Si and 18O were carried out. The coupled analyses of glass, alteration products, and solution led to a complete elemental and isotopic ( 29Si and 18O) budget. They revealed different behaviours of elements that depend not only on their structural role in the glass, but also on their affinity for alteration products (gel, phyllosilicates, phosphates). However, analyses of both glass and solution are not sufficient to describe the real exchanges occurring between glass and solution. The use of 29Si and 18O tracers gives new insights on the formation of alteration layers. During alteration the phyllosilicates records the isotopic variations of the leaching solution. Their isotopic signatures highlight a mechanism of dissolution/precipitation, which implies equilibrium between the secondary phases and the solution. On the other hand the gel isotopic signature, that is intermediate between the glass and the solution, substantiates the hypothesis that the gel is formed by hydrolysis/condensation reactions. This mechanism can thus explain the influence of the gel formation conditions (alteration conditions, solution saturation) on the structure (reorganisation) and texture (porosity) of this layer and on its protective effect. These hydrolysis/condensation reactions are also certainly involved in the aluminosilicate glass alteration and in the formation of palagonite.

  15. Growth of 18O isotopically enriched ZnO nanorods by two novel VPT methods

    NASA Astrophysics Data System (ADS)

    Gray, Ciarán; Trefflich, Lukas; Röder, Robert; Ronning, Carsten; Henry, Martin O.; McGlynn, Enda

    2017-02-01

    We have developed two novel vapour phase transport methods to grow ZnO nanorod arrays isotopically enriched with 18O. Firstly, a three-step process used to grow natural and Zn-enriched ZnO nanorods has been further modified, by replacing the atmospheric O2 with enriched 18O2, in order to grow 18O-enriched ZnO nanorods using this vapour-solid method on chemical bath deposited buffer layers. In addition, 18O-enriched ZnO nanorods were successfully grown using 18O isotopically enriched ZnO source powders in a vapour-liquid-solid growth method. Scanning electron microscopy studies confirmed the success of both growth methods in terms of nanorod morphology, although in the case of the vapour-liquid-solid samples, the nanorods' c-axes were not vertically aligned due to the use of a non-epitaxial substrate. Raman and PL studies indicated clearly that O-enrichment was successful in both cases, although the results indicate that the enrichment is at a lower level in our samples compared to previous reports with the same nominal enrichment levels. The results of our studies also allow us to comment on both levels of enrichment achieved and on novel effects of the high temperature growth environment on the nanorod growth, as well as suggesting possible mechanisms for such effects. Very narrow photoluminescence line widths, far narrower than those reported previously in the literature for isotopically enriched bulk ZnO, are seen in both the vapour-solid and vapour-liquid-solid nanorod samples demonstrating their excellent optical quality and their potential for use in detailed optical studies of defects and impurities using low temperature photoluminescence.

  16. 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

  17. 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.

  18. USGS48 Puerto Rico precipitation - A new isotopic reference material for δ2H and δ18O measurements of water

    USGS Publications Warehouse

    Qi, Haiping; Coplen, Tyler B.; Tarbox, Lauren V.; Lorenz, Jennifer M.; Scholl, Martha A.

    2014-01-01

    A new secondary isotopic reference material has been prepared from Puerto Rico precipitation, which was filtered, homogenised, loaded into glass ampoules, sealed with a torch, autoclaved to eliminate biological activity, and calibrated by dual-inlet isotope-ratio mass spectrometry. This isotopic reference material, designated as USGS48, is intended to be one of two 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 δ2H and δ18O values of this reference water are−2.0±0.4 and−2.224±0.012 ‰, respectively, relative to Vienna Standard Mean Ocean Water on scales normalised such that the δ2H and δ18O values of Standard Light Antarctic Precipitation reference water are−428 and−55.5 ‰, respectively. 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. This isotopic reference water is available by the case of 144 glass ampoules containing 5 mL of water in each ampoule.

  19. 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.

  20. 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

  1. 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.

  2. Terahertz spectroscopy of N18O and isotopic invariant fit of several nitric oxide isotopologs

    NASA Astrophysics Data System (ADS)

    Müller, Holger S. P.; Kobayashi, Kaori; Takahashi, Kazumasa; Tomaru, Kazuko; Matsushima, Fusakazu

    2015-04-01

    A tunable far-infrared laser sideband spectrometer was used to investigate a nitric oxide sample enriched in 18O between 0.99 and 4.75 THz. Regular, electric dipole transitions were recorded between 0.99 and 2.52 THz, while magnetic dipole transitions between the 2Π1/2 and 2Π3/2 spin-ladders were recorded between 3.71 and 4.75 THz. These data were combined with lower frequency data of N18 O (unlabeled atoms refer to 14 N and 16 O, respectively), with rotational data of NO, 15 NO, N17 O, and 15 N18 O, and with heterodyne infrared data of NO to be subjected to one isotopic invariant fit. Rotational, fine and hyperfine structure parameters were determined along with vibrational, rotational, and Born-Oppenheimer breakdown corrections. The resulting spectroscopic parameters permit prediction of rotational spectra suitable for the identification of various nitric oxide isotopologs especially in the interstellar medium by means of rotational spectroscopy.

  3. 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.

  4. Tellurium Stable Isotope Fractionation in Chondritic Meteorites

    NASA Astrophysics Data System (ADS)

    Fehr, M. A.; Hammond, S. J.; Parkinson, I. J.

    2014-09-01

    New Te double spike procedures were set up to obtain high-precision accurate Te stable isotope data. Tellurium stable isotope data for 16 chondrite falls are presented, providing evidence for significant Te stable isotope fractionation.

  5. 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.

  6. 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

  7. 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. 

  8. Stable Isotope Spectroscopy for Diagnostic Medicine

    NASA Astrophysics Data System (ADS)

    Murnick, D. E.

    2000-06-01

    Isotopic tracers have been used in medical research for more than fifty years. Radioactive isotopes have been most used because of the high detection efficiencies possible. With increased awareness of the effects of low level radiation and radioactive waste management problems, the need for safe non radioactive tracers has become apparent. Rare stable isotopes of biologically active elements can be used for metabolic and pharmacokinetic studies provided that both sufficient detection sensitivity can be achieved and reliable cost effective instruments can be developed. High resolution optical spectroscopic methods which can determine isotopic ratios with high precision and accuracy are viable for research and clinical use. The study of 13C/12C ratios in CO2 for breath test diagnostics will be described in detail. Using the laser optogalvonic effect with isotopic lasers a specific medical diagnostic for h-pylori infection, has recently received FDA approval. Opportunities exist to study D/H ratios in water and 18O/16O ratios in CO2 and water for basic metabolism diagnostics and 15N/14N ratios in urine for liver function and related studies.

  9. 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

  10. Treatment methods for the determination of delta2H and delta18O of hair keratin by continuous-flow isotope-ratio mass spectrometry.

    PubMed

    Bowen, Gabriel J; Chesson, Lesley; Nielson, Kristine; Cerling, Thure E; Ehleringer, James R

    2005-01-01

    The structural proteins that comprise approximately 90% of animal hair have the potential to record environmentally and physiologically determined variation in delta2H and delta18O values of body water. Broad, systematic, geospatial variation in stable hydrogen and oxygen isotopes of environmental water and the capacity for rapid, precise measurement via methods such as high-temperature conversion elemental analyzer/isotope ratio mass spectrometry (TC/EA-IRMS) make these isotope systems particularly well suited for applications requiring the geolocation of hair samples. In order for such applications to be successful, however, methods must exist for the accurate determination of hair delta2H and delta18O values reflecting the primary products of biosynthesis. Here, we present the results of experiments designed to examine two potential inaccuracies affecting delta2H and delta18O measurements of hair: the contribution of non-biologic hydrogen and oxygen to samples in the form of sorbed molecular water, and the exchange of hydroxyl-bound hydrogen between hair keratin and ambient water vapor. We show that rapid sorption of molecular water from the atmosphere can have a substantial effect on measured delta2H and delta18O values of hair (comprising approximately 7.7% of the measured isotopic signal for H and up to approximately 10.6% for O), but that this contribution can be effectively removed through vacuum-drying of samples for 6 days. Hydrogen exchange between hair keratin and ambient vapor is also rapid (reaching equilibrium within 3-4 days), with 9-16% of the total hydrogen available for exchange at room temperature. Based on the results of these experiments, we outline a recommended sample treatment procedure for routine measurement of delta2H and delta18O in mammal hair.

  11. Combined 34S, 33S and 18O isotope fractionations record different intracellular steps of microbial sulfate reduction

    NASA Astrophysics Data System (ADS)

    Antler, Gilad; Turchyn, Alexandra V.; Ono, Shuhei; Sivan, Orit; Bosak, Tanja

    2017-04-01

    Several enzymatic steps in microbial sulfate reduction (MSR) fractionate the isotope ratios of 33S/32S, 34S/32S and 18O/16O in extracellular sulfate, but the effects of different intracellular processes on the isotopic composition of residual sulfate are still not well quantified. We measured combined multiple sulfur (33S/32S, 34S/32S) and oxygen (18O/16O) isotope ratios of sulfate in pure cultures of a marine sulfate reducing bacterium Desulfovibrio sp. DMSS-1 grown on different organic substrates. These measurements are consistent with the previously reported correlations of oxygen and sulfur isotope fractionations with the cell-specific rate of MSR: faster reduction rates produced smaller isotopic fractionations for all isotopes. Combined isotope fractionation of oxygen and multiple sulfur isotopes are also consistent with the relationship between the rate limiting step during microbial sulfate reduction and the availability of the DsrC subunit. These experiments help reconstruct and interpret processes that operate in natural pore waters characterized by high 18O/16O and moderate 34S/32S ratios and suggest that some multiple isotope signals in the environment cannot be explained by microbial sulfate reduction alone. Instead, these signals support the presence of active, but slow sulfate reduction as well as the reoxidation of sulfide.

  12. 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

  13. Quantifying uncertainty in stable isotope mixing models

    DOE PAGES

    Davis, Paul; Syme, James; Heikoop, Jeffrey; ...

    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

  14. 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

  15. 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

  16. Stable isotopes in tree rings

    NASA Astrophysics Data System (ADS)

    McCarroll, Danny; Loader, Neil J.

    2004-04-01

    Stable isotopes in tree rings could provide palaeoclimate reconstructions with perfect annual resolution and statistically defined confidence limits. Recent advances make the approach viable for non-specialist laboratories. The relevant literature is, however, spread across several disciplines, with common problems approached in different ways. Here we provide the first overview of isotope dendroclimatology, explaining the underlying theory and describing the steps taken in building and interpreting isotope chronologies. Stable carbon isotopes record the balance between stomatal conductance and photosynthetic rate, dominated at dry sites by relative humidity and soil water status and at moist sites by summer irradiance and temperature. Stable oxygen and hydrogen isotopic ratios record source water, which contains a temperature signal, and leaf transpiration, controlled dominantly by vapour pressure deficit. Variable exchange with xylem (source) water during wood synthesis determines the relative strength of the source water and leaf enrichment signals. Producing long Holocene chronologies will require a change in emphasis towards processing very large numbers of samples efficiently, whilst retaining analytical precision. A variety of sample preparation and data treatment protocols have been used, some of which have a deleterious effect on the palaeoclimate signal. These are reviewed and suggestions made for a more standardised approach.

  17. 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...

  18. 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...

  19. 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

  20. Oxygen isotopes in tree rings record variation in precipitation δ(18)O and amount effects in the south of Mexico.

    PubMed

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

    2013-12-01

    [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 (δ(18)Otr). Interannual variation in δ(18)Otr was highly synchronized between trees and closely related to isotopic composition of rain measured at San Salvador, 710 km to the southwest. Correlations with δ(13)C, growth, or local climate variables (temperature, cloud cover, vapor pressure deficit (VPD)) were relatively low, indicating weak plant physiological influences. Interannual variation in δ(18)Otr 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 (18)O-depleted rain in the region and seem to have affected the δ(18)Otr 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 δ(18)Otr of M. acantholoba can be used as a proxy for source water δ(18)O and that interannual variation in δ(18)Oprec is caused by a regional amount effect. This contrasts with δ(18)O 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

  1. 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

  2. Stable light isotope biogeochemistry of hydrothermal systems.

    PubMed

    Des Marais, D J

    1996-01-01

    The stable isotopic composition of the elements O, H, S and C in minerals and other chemical species can indicate the existence, extent, conditions and the processes (including biological activity) of hydrothermal systems. Hydrothermal alteration of the 18O/16O and D/H values of minerals can be used to detect fossil systems and delineate their areal extent. Water-rock interactions create isotopic signatures which indicate fluid composition, temperature, water-rock ratios, etc. The 18O/16O values of silica and carbonate deposits tend to increase with declining temperature and thus help to map thermal gradients. Measurements of D/H values can help to decipher the origin(s) of hydrothermal fluids. The 34S/32S and 13C/12C values of fluids and minerals reflect the origin of the S and C as well as oxygen fugacities and key redox processes. For example, a wide range of 34S/32S values which are consistent with equilibration below 100 degrees C between sulfide and sulfate can be attributed to sulfur metabolizing bacteria. Depending on its magnitude, the difference in the 13C/12C value of CO2 and carbonates versus organic carbon might be attributed either to equilibrium at hydrothermal temperatures or, if the difference exceeds 1% (10/1000), to organic biosynthesis. Along the thermal gradients of thermal spring outflows, the 13C/12C value of carbonates and 13C-depleted microbial organic carbon increases, principally due to the outgassing of relatively 13C-depleted CO2.

  3. 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.).

  4. Stable isotopic variations in precipitation in Southwest China

    NASA Astrophysics Data System (ADS)

    Zhang, Xinping; Jin, Huijun; Sun, Weizhen

    2006-12-01

    This study analyzes the relationships of stable isotopes in precipitation with temperature, air pressure and humidity at different altitudes, and the potential influencing mechanisms of control factors on the stable isotopes in precipitation in Southwest China. There appear marked negative correlations of the δ 18O in precipitation with precipitation amount, vapor pressure and atmospheric precipitable water (PW) at the Mengzi, Simao and Tengchong stations on the synoptic timescale; the marked negative correlations between the δ 18O in precipitation and the diurnal mean temperature at 400 hPa, 500 hPa, 700 hPa and 850 hPa are different from the temperature effect in middle-high-latitude inland areas. In addition, the notable positive correlation between the δ 18O in precipitation and the dew-point deficit Δ T d at different altitudes is found at the three stations. Precipitation is not the only factor generating an amount effect. Probably, the amount effect is related to the variations of atmospheric circulation and vapor origins. On the annual timescale, the annual precipitation amount weighted-mean δ 18O displays negative correlations not only with annual precipitation but also with annual mean temperature at 500 hPa. It can be deduced that, in the years with an abnormally strong summer monsoon, more warm and wet air from low-latitude oceans is transported northward along the vapor channel located in Southwest China and generates abnormally strong rainfall on the way. Meanwhile, the abnormally strong condensation process will release more condensed latent heat in the atmosphere, and this will lead to a rise of atmospheric temperature during rainfall but a decline of δ 18O in the precipitation. On the other hand, in the years with an abnormally weak summer monsoon, the precipitation and the atmospheric temperature during rainfalls decrease abnormally but the δ 18O in precipitation increases.

  5. Aberrant Water Homeostasis Detected by Stable Isotope Analysis

    PubMed Central

    O'Grady, Shannon P.; Wende, Adam R.; Remien, Christopher H.; Valenzuela, Luciano O.; Enright, Lindsey E.; Chesson, Lesley A.; Abel, E. Dale; Cerling, Thure E.; Ehleringer, James R.

    2010-01-01

    While isotopes are frequently used as tracers in investigations of disease physiology (i.e., 14C labeled glucose), few studies have examined the impact that disease, and disease-related alterations in metabolism, may have on stable isotope ratios at natural abundance levels. The isotopic composition of body water is heavily influenced by water metabolism and dietary patterns and may provide a platform for disease detection. By utilizing a model of streptozotocin (STZ)-induced diabetes as an index case of aberrant water homeostasis, we demonstrate that untreated diabetes mellitus results in distinct combinations, or signatures, of the hydrogen (δ2H) and oxygen (δ18O) isotope ratios in body water. Additionally, we show that the δ2H and δ18O values of body water are correlated with increased water flux, suggesting altered blood osmolality, due to hyperglycemia, as the mechanism behind this correlation. Further, we present a mathematical model describing the impact of water flux on the isotopic composition of body water and compare model predicted values with actual values. These data highlight the importance of factors such as water flux and energy expenditure on predictive models of body water and additionally provide a framework for using naturally occurring stable isotope ratios to monitor diseases that impact water homeostasis. PMID:20657736

  6. Isotopic (18O) characteristics of weekly precipitation collected across the USA: an initial analysis with application to water source studies

    NASA Astrophysics Data System (ADS)

    Welker, J. M.

    2000-06-01

    A portion of the precipitation samples collected and stored by the National Atmospheric Deposition Program (NADP) are shown to be useful for analysis of isotopes in precipitation. The potential problems with evaporation are small based on deuterium excess analyses and comparisons with the Global Meteroic Water Line. Presented here are the 18O values of precipitation collected from nine NADP sites during 1989, 1990 and 1991. The trends in the isotopic (18O) characteristics of recent precipitation are in agreement with findings from previous International Atomic Energy Agency (IAEA) sites in the USA. The findings are also in agreement with several major isotope-environment relationships, further supporting the use of these samples for a modern global data base on the isotopes in precipitation being developed by IAEA, called GNIP (Global Network for Isotopes in Precipitation) and for use by research groups in the hydrological modelling, palaeoclimate and ecological communities.As expected, the average 18O values of precipitation that is derived from the Gulf of Mexico (-3) and from the Pacific North-west are isotopically distinct (-7). In addition, using the NADP network, isotopic depletion in the 18O values of precipitation in the range of 8 was observed from coastal to inland locations either in the Pacific North-west or along the east side of the Rocky Mountains, from Texas to Eastern Montana. In central USA, especially at high elevation, there is a strong seasonal variation in the 18O values of precipitation, differing by almost 25 between January and August, whereas at coastal locations the seasonal variation in the 18O values of precipitation was minimal. Comparisons between the average 18

  7. A Two-year Record of Daily Rainfall Isotopes from Fiji: Implications for Reconstructing Precipitation from Speleothem δ18O

    NASA Astrophysics Data System (ADS)

    Brett, M.; Mattey, D.; Stephens, M.

    2015-12-01

    Oxygen isotopes in speleothem provide opportunities to construct precisely dated records of palaeoclimate variability, underpinned by an understanding of both the regional climate and local controls on isotopes in rainfall and groundwater. For tropical islands, a potential means to reconstruct past rainfall variability is to exploit the generally high correlation between rainfall amount and δ18O: the 'amount effect'. The GNIP program provides δ18O data at monthly resolution for several tropical Pacific islands but there are few data for precipitation isotopes at daily resolution, for investigating the amount effect over different timescales in a tropical maritime setting. Timescales are important since meteoric water feeding a speleothem has undergone storage and mixing in the aquifer system and understanding how the isotope amount effect is preserved in aquifer recharge has fundamental implications on the interpretation of speleothem δ18O in terms of palaeo-precipitation. The islands of Fiji host speleothem caves. Seasonal precipitation is related to the movement of the South Pacific Convergence Zone, and interannual variations in rainfall are coupled to ENSO behaviour. Individual rainfall events are stratiform or convective, with proximal moisture sources. We have daily resolution isotope data for rainfall collected at the University of the South Pacific in Suva, covering every rain event in 2012 and 2013. δ18O varies between -18‰ and +3‰ with the annual weighted averages at -7.6‰ and -6.8‰ respectively, while total recorded rainfall amount is similar in both years. We shall present analysis of our data compared with GNIP, meteorological data and back trajectory analyses to demonstrate the nature of the relationship between rainfall amount and isotopic signatures over this short timescale. Comparison with GNIP data for 2012-13 will shed light on the origin of the amount effect at monthly and seasonal timescales in convective, maritime, tropical

  8. 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

  9. 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

  10. 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)

  11. 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

  12. 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

  13. Periodicity analysis of δ18O in precipitation over Central Europe: Time-frequency considerations of the isotopic 'temperature' effect

    NASA Astrophysics Data System (ADS)

    Salamalikis, V.; Argiriou, A. A.; Dotsika, E.

    2016-03-01

    In this paper the periodic patterns of the isotopic composition of precipitation (δ18O) for 22 stations located around Central Europe are investigated through sinusoidal models and wavelet analysis over a 23 years period (1980/01-2002/12). The seasonal distribution of δ18O follows the temporal variability of air temperature providing seasonal amplitudes ranging from 0.94‰ to 4.47‰; the monthly isotopic maximum is observed in July. The isotopic amplitude reflects the geographical dependencies of the isotopic composition of precipitation providing higher values when moving inland. In order to describe the dominant oscillation modes included in δ18O time series, the Morlet Continuous Wavelet Transform is evaluated. The main periodicity is represented at 12-months (annual periodicity) where the wavelet power is mainly concentrated. Stations (i.e. Cuxhaven, Trier, etc.) with limited seasonal isotopic effect provide sparse wavelet power areas at the annual periodicity mode explaining the fact that precipitation has a complex isotopic fingerprint that cannot be examined solely by the seasonality effect. Since temperature is the main contributor of the isotopic variability in mid-latitudes, the isotope-temperature effect is also investigated. The isotope-temperature slope ranges from 0.11‰/°C to 0.47‰/°C with steeper values observed at the southernmost stations of the study area. Bivariate wavelet analysis is applied in order to determine the correlation and the slope of the δ18O - temperature relationship over the time-frequency plane. High coherencies are detected at the annual periodicity mode. The time-frequency slope is calculated at the annual periodicity mode ranging from 0.45‰/°C to 0.83‰/°C with higher values at stations that show a more distinguishable seasonal isotopic behavior. Generally the slope fluctuates around a mean value but in certain cases (sites with low seasonal effect) abrupt slope changes are derived and the slope becomes

  14. Stalagmite stable isotope record of recent tropical cyclone events

    NASA Astrophysics Data System (ADS)

    Benoit Frappier, Amy; Sahagian, Dork; Carpenter, Scott J.; González, Luis A.; Frappier, Brian R.

    2007-02-01

    We present a 23 yr stalagmite record (1977 2000) of oxygen isotope variation, associated with 11 tropical cyclones (TCs), from Actun Tunichil Muknal cave in central Belize. High-resolution microsampling yielded a record of monthly to weekly temporal resolution that contains abrupt decreases (negative excursions) in calcite δ18O values that correspond with recent TC rain events nearby. A logistic discriminant model reliably identified TC proxy signals using the measurable parameters δ18O and δ13C values, and single point changes in δ18O value. The logistic model correctly identified 80% of excursions as TC events and incorrectly classified only 1 of nearly 1200 nonstorm sampling points. In addition to enabling high-resolution TC frequency reconstruction, this geologic proxy also provides information about the intensity of individual TCs. A multiple regression predicted TC intensity (R2 = 0.465, p = 0.034) using sampling frequency and excursion amplitude. Consistent with previous low-resolution studies, we found that the decadal average δ18O value was lower during the 1990s when several TCs produced rainfall in the area, but higher during the 1980s when only one TC struck. Longer, accurately dated, high-resolution speleothem stable isotope records may be a useful new tool for paleotempestology, to clarify associations between highly variable TC activity and the dynamic range of Quaternary climate.

  15. 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.

  16. Stable isotope analyses of palaeo-pollen records

    NASA Astrophysics Data System (ADS)

    Hemming, D.; Loader, N.

    2002-12-01

    Pollen stratigraphy is one of the most widely used tools for studying climate and vegetation dynamics over global and multi-millennial scales. Since the isotopic compositions of photosynthates that are used to form the pollen structure reflect environmental conditions during the time of pollen formation, the stable carbon, oxygen and hydrogen isotopic compositions (δ13C, δ18O and δ{}D) of the pollen grains may reflect this environmental information. Although there are many preliminary tests and methodological problems to overcome before we can fully utilise palaeo-pollen records, it is the general goal of our research to use pollen isotope records together with conventional palynological analyses to provide additional, independent spatial and temporal palaeo-environmental information and to provide new data on terrestrial ecosystem dynamics, including the timing of environmental changes, phase relationships of vegetation responses and regional and temporal variations in δ13C, Δ13C, δ18O and δ{}D. These isotopic records will facilitate in the modelling of palaeo-environments. By separating and analysing different pollen species, including C3 and C4, we also aim to assess species-specific climatic responses. We present results describing some recent investigations concerning the nature of the isotopic signal contained within pollen, the methodological developments we have made to measure the pollen isotopic composition and the future challenges that must be overcome before this potentially powerful quantitative terrestrial palaeo-archive can be fully and correctly utilised.

  17. Physiological and isotopic (delta(13)C and delta(18)O) responses of three tropical tree species to water and nutrient availability.

    PubMed

    Cernusak, Lucas A; Winter, Klaus; Turner, Benjamin L

    2009-10-01

    Water-use efficiency and stable isotope composition were studied in three tropical tree species. Seedlings of Tectona grandis, Swietenia macrophylla and Platymiscium pinnatum were grown at either high or low water supply, and with or without added fertilizer. These three species previously exhibited low, intermediate and high whole-plant water-use efficiency (TE) when grown at high water supply in unfertilized soil. Responses of TE to water and nutrient availability varied among species. The TE was calculated as experiment-long dry matter production divided by cumulative water use. Species-specific offsets were observed in relationships between TE and whole-plant (13)C discrimination (Delta(13)C(p)). These offsets could be attributed to a breakdown in the relationship between Delta(13)C(p) and the ratio of intercellular to ambient CO(2) partial pressures (c(i)/c(a)) in P. pinnatum, and to variation among species in the leaf-to-air vapour pressure difference (v). Thus, a plot of v.TE against c(i)/c(a) showed a general relationship among species. Relationships between delta(18)O of stem dry matter and stomatal conductance ranged from strongly negative for S. macrophylla to no relationship for T. grandis. Results suggest inter-specific variation among tropical tree species in relationships between stable isotope ratios (delta(13)C and delta(18)O) and the gas exchange processes thought to affect them.

  18. 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

  19. Isotopic effects in the ( π±, 2N) reactions on 16O and 18O

    NASA Astrophysics Data System (ADS)

    Altman, A.; Ashery, D.; Piasetzky, E.; Lichtenstadt, J.; Yavin, A. I.; Bertl, W.; Felawka, L.; Walter, H. K.; Powers, R. J.; Winter, R. G.; v. d. Pluym, J.

    1984-09-01

    The ( π+, 2p), ( π+, pn) and ( π-, pn) reactions on 16O and 18O were studied at 165 MeV. The cross section for the ( π+, 2p) reaction on 18O is larger than that for 16O be only 5% ± 3%, while the total π+ absorption cross section is larger by 17% ± 5%. This supports the assumption that two-nucleon absorption occurs mainly on nucleons in the same shell. It is further concluded that Δ++n → pp is not only absorption mechanism that couples strongly to the nucleon knock out reactions.

  20. 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...

  1. 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

  2. Primary Productivity Rates at Station ALOHA Determined by 18O Labeling and the Triple Isotope Composition of Dissolved Oxygen

    NASA Astrophysics Data System (ADS)

    Juranek, L. W.; Quay, P. D.; Karl, D. M.

    2002-12-01

    Although knowledge of accurate Primary Productivity (PPr) rates is essential to the understanding of ocean carbon cycling, the standard method of determining ocean productivity, 14C labeling, often yields uncertain results. Typically, 14C-derived PPr rates fall ambiguously between gross and net productivity because the method is sensitive to recycling of a relatively small POC pool. Bottle incubations using labeled oxygen produced from 18O-enriched water have shown promise in giving a more consistent measure of gross productivity, since the pool of dissolved oxygen is less sensitive to recycling than POC. Typically this method gives gross PPr rates that are 2-3 times 14C-derived rates. Recently Luz and Barkan (2001) have pioneered a new technique to determine PPr rates using the triple isotope composition of dissolved oxygen as an in situ tracer. This relies on the observation that a signature of mass-independent fractionation originating in the stratosphere and imparted to the surface ocean by air-sea exchange is diminished by biological oxygen production. In February 2002 we measured gross productivity using both the 18O-labeling and triple isotope in situ methods at Hawaii Ocean Time-Series station ALOHA in the N. Pacific subtropical gyre. We found the in situ oxygen isotope method yielded double the 14C-derived PPr rates while 18O bottle incubations yielded similar rates as 14C. In addition, comparison of in situ isotope measurements with the biological oxygen saturation state indicate that community respiration is approximately equal to gross photosynthesis in the upper 60 m while from 80-200 m respiration exceeds photosynthesis by at most 10 %. We will present these results along with new results from upcoming measurements at station ALOHA.

  3. 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

  4. Isotopic composition (δ18O and δD) of the shallow groundwater in the Poyang Lake basin

    NASA Astrophysics Data System (ADS)

    Soldatova, E. A.; Sun, Z.; Guseva, N. V.

    2016-03-01

    The article is focused on the identification of evaporation and other natural processes which affect the isotopic composition of shallow groundwater in the Poyang Lake basin, such as water-rock interaction and mixing of the shallow groundwater and surface water. For this purpose the dual isotope approach (δD-H2O and δ18O-H2O) was used. The samples were collected from domestic wells around the Poyang Lake. The value of δD obtained for the shallow groundwater ranges from -21.5 to -42.6∘/∘∘. The δ18O value varies from -3.5 to -7.1∘/∘∘. It was found that the shallow groundwater of the Poyang Lake catchment is of meteoric origin. The influence of evaporation on the isotopic composition of shallow groundwater is negligible and observed mainly during the dry season. The deviation from the local meteoric water line, especially during the rainy season, may be explained by the processes in the water-rock system, but this issue is required further research.

  5. 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

  6. Ab initio path integral simulation study on 16O/ 18O isotope effect in water and hydronium ion

    NASA Astrophysics Data System (ADS)

    Tachikawa, Masanori; Shiga, Motoyuki

    2005-05-01

    An ab initio path integral molecular dynamics simulation has been performed to study the 16O and 18O isotopomers for a water molecule and a hydronium ion at temperature 300 K. The average O-H bond length of H 218O molecule is slightly shorter than that of H 216O molecule, while that of H 318O + is slightly longer than that of H 316O +. For hydronium ions, the Walden inversion of H 318O +, as well as D 316O +, is found to be more restrained than that of H 316O +. The isotope effect in the electronic structure and thermochemical properties for these isotopomers are also shown.

  7. Investigating human geographic origins using dual-isotope (87Sr/86Sr, δ18O) assignment approaches

    PubMed Central

    Sonnemann, Till F.; Shafie, Termeh; Hofman, Corinne L.; Brandes, Ulrik; Davies, Gareth R.

    2017-01-01

    Substantial progress in the application of multiple isotope analyses has greatly improved the ability to identify nonlocal individuals amongst archaeological populations over the past decades. More recently the development of large scale models of spatial isotopic variation (isoscapes) has contributed to improved geographic assignments of human and animal origins. Persistent challenges remain, however, in the accurate identification of individual geographic origins from skeletal isotope data in studies of human (and animal) migration and provenance. In an attempt to develop and test more standardized and quantitative approaches to geographic assignment of individual origins using isotopic data two methods, combining 87Sr/86Sr and δ18O isoscapes, are examined for the Circum-Caribbean region: 1) an Interval approach using a defined range of fixed isotopic variation per location; and 2) a Likelihood assignment approach using univariate and bivariate probability density functions. These two methods are tested with enamel isotope data from a modern sample of known origin from Caracas, Venezuela and further explored with two archaeological samples of unknown origin recovered from Cuba and Trinidad. The results emphasize both the potential and limitation of the different approaches. Validation tests on the known origin sample exclude most areas of the Circum-Caribbean region and correctly highlight Caracas as a possible place of origin with both approaches. The positive validation results clearly demonstrate the overall efficacy of a dual-isotope approach to geoprovenance. The accuracy and precision of geographic assignments may be further improved by better understanding of the relationships between environmental and biological isotope variation; continued development and refinement of relevant isoscapes; and the eventual incorporation of a broader array of isotope proxy data. PMID:28222163

  8. 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.

  9. Modeling Interannual Variability of δ^1^8O of Atmospheric CO2 and its Dependence on Humidity and Isotope Hydrology

    NASA Astrophysics Data System (ADS)

    Buenning, N. H.; Noone, D. C.; Still, C. J.; Riley, W. J.; Randerson, J. T.; Welp, L. R.; White, J. W.; Vaughn, B.; Miller, J. B.; Tans, P. P.

    2006-12-01

    Measurements of the δ^1^8O value of CO2 at the NOAA/ESRL baseline observatories showed a gradual downward trend from the early 1990s until 1997. The cause of this trend is not well understood, although it is likely due to a change in the isotopic composition of the terrestrial water pools with which CO2 interacts during photosynthesis and respiration, particularly in the tropics, where the largest isotope forcing occurs. There are a number of factors that affect the isotopic composition of soil and leaf water, however, studies have indicated that relative humidity has a strong impact on the water pools. Humidity records at several stations in Southeast Asia show an upward trend during the 1990s, which is consistent with the expected trend in the δ^1^8O value of atmospheric CO2. While an increase in humidity would increase stomatal conductance and in turn increase biospheric productivity, it also will allow leaves to take in more of the isotopically light water vapor, causing the leaf water to become less enriched with ^1^8O isotope. Using the isotopic version of the NCAR Land Surface Model (ISOLSM) and Community Atmosphere Model (CAM), the interannual variability of simulated δ^1^8O of CO2 were examined from 1979 to 2002. ISOLSM was forced with interannually varying meteorological data from the NCEP reanalysis. Computed fluxes from ISOLSM for each month of the 24-year simulation were used in CAM to simulate the seasonal cycle and trends in δ^1^8O values of CO2. Experiments were constructed to determine the impact on interannual variability in the δ^1^8O value of CO2 of humidity, δ^1^8O of precipitation, and δ^1^8O of water vapor. To demonstrate the affect of humidity, two experiments were constructed whereby relative humidity (1) is gradually increased by 0.5% per year from 1990 to 1997 (as is seen in some of the humidity records in Southeast Asia during the early 1990s yet this trend does not appear in the NCEP Reanalysis) and (2) assigned long-term monthly

  10. 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.

  11. 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

  12. Results from the stable isotope sampling network in Carboeuroflux

    NASA Astrophysics Data System (ADS)

    Yakir, D.; Hemming, D.

    2002-12-01

    Integrating stable isotopic measurements of canopy air and ecosystem organics with flux tower and ecophysiological data provides a powerful tool to differentiate between carbon sources and sinks, and scale-up processes from plant to ecosystem levels. During the 2001 and 2002 growing-seasons monthly flask samples of nocturnal canopy air and ecosystem organics were collected from selected forest flux sites within the Carboeuroflux network (13 sites in 2001 and 18 in 2002). Flask air was analysed for CO2 concentration ([CO2]), and the carbon and oxygen isotopic compositions (δ13C and δ18O) of this CO2. The δ18O of waters distilled from leaf, stem and soil samples, and the δ13C and δ18O of these dried, homogonised organic samples were also measured. Analytical precisions were ñ0.1ppmv for [CO2], ñ0.1 permil and ñ0.2 permil for the δ13C and δ18O of atmospheric CO2, ñ0.05 permil for water δ18O and ñ0.1 permil for both the δ13C and δ18O of organics. The δ13C of ecosystem respired CO2 (δ13CR) was determined for each sampling period and location using a Keeling plot approach. Ecosystem discrimination (Δ13CE) was estimated as the difference between the δ13Cs of background atmospheric CO2 and ecosystem respired CO2. The seasonal and spatial variation in these variables, and the δ13C and δ18O compositions of the organic samples are examined relative to meteorological and ecophysiological conditions. We assessed the potential for using the δ18O of ecosystem respired CO2 (δ18OR) together with that of soil and leaf waters to partition between the soil and above-ground respired CO2 sources. At sites where soil δ13C varied significantly from leaf δ13C, we also assessed the partitioning potential in using the δ13C data. More intensive sampling campaigns, including incubations in branch-bags, and leaf, trunk and soil chambers, were also conducted at specific sites to examine the partitioning and scale relationships between individual source CO2 contributions

  13. 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

  14. 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.

  15. 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.

  16. 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.

  17. Abundant climatic information in water stable isotope record from a maritime glacier on southeastern Tibetan Plateau

    NASA Astrophysics Data System (ADS)

    Zhao, Huabiao; Xu, Baiqing; Li, Zhen; Wang, Mo; Li, Jiule; Zhang, Xiaolong

    2017-02-01

    Climatic significance of ice core stable isotope record in the Himalayas and southern Tibetan Plateau (TP), where the climate is alternately influenced by Indian summer monsoon and mid-latitude westerlies, is still debated. A newly drilled Zuoqiupu ice core from a temperate maritime glacier on the southeastern TP covering 1942-2011 is investigated in terms of the relationships between δ18O and climate parameters. Distinct seasonal variation of δ18O is observed due to high precipitation amount in this area. Thus the monsoon (June to September) and non-monsoon (October to May) δ18O records are reconstructed, respectively. The temperature effect is identified in the annual δ18O record, which is predominantly contributed by temperature control on the non-monsoon precipitation δ18O record. Conversely, the negative correlation between annual δ18O record and precipitation amount over part of Northeast India is mostly contributed by the monsoon precipitation δ18O record. The variation of monsoon δ18O record is greatly impacted by the Indian summer monsoon strength, while that of non-monsoon δ18O record is potentially associated with the mid-latitude westerly activity. The relationship between Zuoqiupu δ18O record and Sea Surface Temperature (SST) is found to be inconsistent before and after the climate shift of 1976/1977. In summer monsoon season, the role of SST in the monsoon δ18O record is more important in eastern equatorial Pacific Ocean and tropical Indian Ocean before and after the shift, respectively. In non-monsoon season, however, the Atlantic Multidecadal Oscillation has a negative impact before but positive impact after the climate shift on the non-monsoon δ18O record.

  18. 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...

  19. 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

  20. Tracking ENSO with tropical trees: Progress in stable isotope dendroclimatology

    NASA Astrophysics Data System (ADS)

    Evans, M. N.; Poussart, P. F.; Saleska, S. R.; Schrag, D. P.

    2002-12-01

    The terrestrial tropics remain an important gap in the growing proxy network used to characterize past ENSO behavior. Here we describe a strategy for development of proxy estimates of paleo-ENSO, via proxy rainfall estimates derived from stable isotope18O) measurements made on tropical trees. The approach applies a new model of oxygen isotopic composition of alpha-cellulose (Roden et al., 2000), a rapid method for cellulose extraction from raw wood (Brendel et al., 2000), and continuous flow isotope ratio mass spectrometry (Brand, 1996) to develop proxy chronological, rainfall and growth rate estimates from tropical trees, even those lacking annual rings. The promise and pitfalls of the approach are illustrated in pilot datasets from the US, Costa Rica, Brazil, and Peru, which show isotopic cycles of 4-6 per mil, and interannual anomalies of up to 8 per mil. Together with the mature ENSO proxies (corals, extratropical tree-rings, varved sediments, and ice cores), replicated and well-dated stable isotope chronologies from tropical trees may eventually improve our understanding of ENSO history over the past several hundred years.

  1. 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).

  2. 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.

  3. 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. "

  4. 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

  5. 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???.

  6. 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

  7. 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.

  8. 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

  9. 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...

  10. 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

  11. 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

  12. Applications of stable isotopes in clinical pharmacology

    PubMed Central

    Schellekens, Reinout C A; Stellaard, Frans; Woerdenbag, Herman J; Frijlink, Henderik W; Kosterink, Jos G W

    2011-01-01

    This review aims to present an overview of the application of stable isotope technology in clinical pharmacology. Three main categories of stable isotope technology can be distinguished in clinical pharmacology. Firstly, it is applied in the assessment of drug pharmacology to determine the pharmacokinetic profile or mode of action of a drug substance. Secondly, stable isotopes may be used for the assessment of drug products or drug delivery systems by determination of parameters such as the bioavailability or the release profile. Thirdly, patients may be assessed in relation to patient-specific drug treatment; this concept is often called personalized medicine. In this article, the application of stable isotope technology in the aforementioned three areas is reviewed, with emphasis on developments over the past 25 years. The applications are illustrated with examples from clinical studies in humans. PMID:21801197

  13. Contributions of evaporation, isotopic non-steady state transpiration and atmospheric mixing on the delta18O of water vapour in Pacific Northwest coniferous forests.

    PubMed

    Lai, Chun-Ta; Ehleringer, James R; Bond, Barbara J; Paw U, Kyaw Tha

    2006-01-01

    Changes in the 2H and 18O of atmospheric water vapour provide information for integrating aspects of gas exchange within forest canopies. In this study, we show that diurnal fluctuations in the oxygen isotope ratio (delta 18O) as high as 4% per hundred were observed for water vapour (delta (18)Ovp) above and within an old-growth coniferous forest in the Pacific Northwest region of the United States. Values of delta 18Ovp decreased in the morning, reached a minimum at midday, and recovered to early-morning values in the late afternoon, creating a nearly symmetrical diurnal pattern for two consecutive summer days. A mass balance budget was derived and assessed for the 18O of canopy water vapour over a 2-d period by considering the 18O-isoflux of canopy transpiration, soil evaporation and the air entering the canopy column. The budget was used to address two questions: (1) do delta 18O values of canopy water vapour reflect the biospheric influence, or are such signals swamped by atmospheric mixing? and (2) what mechanisms drive temporal variations of delta 18Ovp? Model calculations show that the entry of air into the canopy column resulted in an isotopically depleted 18O-isoflux in the morning of day 1, causing values of delta 18Ovp, to decrease. An isotopically enriched 18O-isoflux resulting from transpiration then offset this decreased delta 18Ovp later during the day. Contributions of 18O-isoflux from soil evaporation were relatively small on day 1 but were more significant on day 2, despite the small H2(16)O fluxes. From measurements of leaf water volume and sapflux, we determined the turnover time of leaf water in the needles of Douglas-fir trees as approximately 11 h at midday. Such an extended turnover time suggests that transpiration may not have occurred at the commonly assumed isotopic steady state. We tested a non-steady state model for predicting delta 18O of leaf water. Our model calculations show that assuming isotopic steady state increased isoflux of

  14. Divergence of stable isotopes in tap water across China

    NASA Astrophysics Data System (ADS)

    Zhao, Sihan; Hu, Hongchang; Tian, Fuqiang; Tie, Qiang; Wang, Lixin; Liu, Yaling; Shi, Chunxiang

    2017-03-01

    Stable isotopes in water (e.g., δ2H and δ18O) are important indicators of hydrological and ecological patterns and processes. Tap water can reflect integrated features of regional hydrological processes and human activities. China is a large country with significant meteorological and geographical variations. This report presents the first national-scale survey of Stable Isotopes in Tap Water (SITW) across China. 780 tap water samples have been collected from 95 cities across China from December 2014 to December 2015. (1) Results yielded the Tap Water Line in China is δ2H = 7.72 δ18O + 6.57 (r2 = 0.95). (2) SITW spatial distribution presents typical “continental effect”. (3) SITW seasonal variations indicate clearly regional patterns but no trends at the national level. (4) SITW can be correlated in some parts with geographic or meteorological factors. This work presents the first SITW map in China, which sets up a benchmark for further stable isotopes research across China. This is a critical step toward monitoring and investigating water resources in climate-sensitive regions, so the human-hydrological system. These findings could be used in the future to establish water management strategies at a national or regional scale.

  15. Divergence of stable isotopes in tap water across China.

    PubMed

    Zhao, Sihan; Hu, Hongchang; Tian, Fuqiang; Tie, Qiang; Wang, Lixin; Liu, Yaling; Shi, Chunxiang

    2017-03-02

    Stable isotopes in water (e.g., δ(2)H and δ(18)O) are important indicators of hydrological and ecological patterns and processes. Tap water can reflect integrated features of regional hydrological processes and human activities. China is a large country with significant meteorological and geographical variations. This report presents the first national-scale survey of Stable Isotopes in Tap Water (SITW) across China. 780 tap water samples have been collected from 95 cities across China from December 2014 to December 2015. (1) Results yielded the Tap Water Line in China is δ(2)H = 7.72 δ(18)O + 6.57 (r(2) = 0.95). (2) SITW spatial distribution presents typical "continental effect". (3) SITW seasonal variations indicate clearly regional patterns but no trends at the national level. (4) SITW can be correlated in some parts with geographic or meteorological factors. This work presents the first SITW map in China, which sets up a benchmark for further stable isotopes research across China. This is a critical step toward monitoring and investigating water resources in climate-sensitive regions, so the human-hydrological system. These findings could be used in the future to establish water management strategies at a national or regional scale.

  16. Divergence of stable isotopes in tap water across China

    PubMed Central

    Zhao, Sihan; Hu, Hongchang; Tian, Fuqiang; Tie, Qiang; Wang, Lixin; Liu, Yaling; Shi, Chunxiang

    2017-01-01

    Stable isotopes in water (e.g., δ2H and δ18O) are important indicators of hydrological and ecological patterns and processes. Tap water can reflect integrated features of regional hydrological processes and human activities. China is a large country with significant meteorological and geographical variations. This report presents the first national-scale survey of Stable Isotopes in Tap Water (SITW) across China. 780 tap water samples have been collected from 95 cities across China from December 2014 to December 2015. (1) Results yielded the Tap Water Line in China is δ2H = 7.72 δ18O + 6.57 (r2 = 0.95). (2) SITW spatial distribution presents typical “continental effect”. (3) SITW seasonal variations indicate clearly regional patterns but no trends at the national level. (4) SITW can be correlated in some parts with geographic or meteorological factors. This work presents the first SITW map in China, which sets up a benchmark for further stable isotopes research across China. This is a critical step toward monitoring and investigating water resources in climate-sensitive regions, so the human-hydrological system. These findings could be used in the future to establish water management strategies at a national or regional scale. PMID:28252670

  17. 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.

  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. Stable carbon isotope analysis of coprocessing materials

    SciTech Connect

    Winschel, R.A.; Lancet, M.S.; Burke, F.P.

    1991-04-01

    This is the final report which was a thirty-four month project conducted to develop and demonstrate stable carbon isotope analysis as a method to quantitatively distinguish the source of carbon in products of coal/petroleum coprocessing. The work included assessing precision, accuracy, the range of application and the significance of selective isotopic fractionation effects. A method was devised to correct for selective isotopic fractionation errors. The method was demonstrated through application with samples from twelve continuous-unit coprocessing tests. A data base of carbon isotope analyses is appended. 21 refs.

  20. The Kuo-Brown effective interaction: From 18O to the Sn isotopes

    NASA Astrophysics Data System (ADS)

    Engeland, Torgeir; Hjorth-Jensen, Morten; Kartamyshev, Maxim; Osnes, Eivind

    2014-08-01

    After briefly reviewing the pioneering work on effective interactions by Gerry Brown and his group, and the developments which followed, we apply present-day effective interactions to large-scale shell-model calculations on the entire range of Sn isotopes from 102Sn to 132Sn. We have made explorative calculations starting from three different nucleon-nucleon potentials (Argonne V18, CD-Bonn, and N3LO) and evaluated the higher-order contributions to the effective interaction from both G-matrix and Vlowk interactions. Further, we have checked the convergence of intermediate-state excitations up to 10ħω harmonic oscillator energy. Final extensive calculations were made of binding energies, excitation energies and B(E2) transition rates using an effective interaction based on a G-matrix evaluated from the chiral N3LO potential and including intermediate excitations up to 10ħω harmonic oscillator energy. The energy spectra are well reproduced throughout the region while overbinding of the ground states emerges as valence nucleons are added. The B(E2) rates agree well for the heavy isotopes, while they seem too low for the lighter ones.

  1. 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.

  2. [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.

  3. 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

  4. Validation of heavy-water stable isotope probing for the characterization of rapidly responding soil bacteria.

    PubMed

    Aanderud, Zachary T; Lennon, Jay T

    2011-07-01

    Rapid responses of bacteria to sudden changes in their environment can have important implications for the structure and function of microbial communities. In this study, we used heavy-water stable isotope probing (H2(18)O-SIP) to identify bacteria that respond to soil rewetting. First, we conducted experiments to address uncertainties regarding the H2(18)O-SIP method. Using liquid chromatography-mass spectroscopy (LC-MS), we determined that oxygen from H2(18)O was incorporated into all structural components of DNA. Although this incorporation was uneven, we could effectively separate 18O-labeled and unlabeled DNAs derived from laboratory cultures and environmental samples that were incubated with H2(18)O. We found no evidence for ex vivo exchange of oxygen atoms between DNA and extracellular H2O, suggesting that 18O incorporation into DNA is relatively stable. Furthermore, the rate of 18O incorporation into bacterial DNA was high (within 48 to 72 h), coinciding with pulses of CO2 generated from soil rewetting. Second, we examined shifts in the bacterial composition of grassland soils following rewetting, using H2(18)O-SIP and bar-coded pyrosequencing of 16S rRNA genes. For some groups of soil bacteria, we observed coherent responses at a relatively course taxonomic resolution. Following rewetting, the relative recovery of Alphaproteobacteria, Betaproteobacteria, and Gammaproteobacteria increased, while the relative recovery of Chloroflexi and Deltaproteobacteria decreased. Together, our results suggest that H2(18)O-SIP is effective at identifying metabolically active bacteria that influence soil carbon dynamics. Our results contribute to the ecological classification of soil bacteria while providing insight into some of the functional traits that influence the structure and function of microbial communities under dynamic soil moisture regimes.

  5. 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

  6. 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.

  7. 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.

  8. Stable Isotope Laser Spectrometer for Exploration of Mars

    NASA Technical Reports Server (NTRS)

    Sauke, Todd B.; Becker, Joseph F.

    1998-01-01

    On Earth, measurements of the ratios of stable carbon isotopes have providet much information about geological and biological processes. For example, fractionation of carbon occur in biotic processes and the retention of a distinctive 2-4% contrast in C-13/C-12 between organic carbon and carbonates in rocks as old as 3.8 billion years constitutes some of the firmest evidence for the antiquity of life on the Earth. We have developed a prototype tunable diode laser spectrometer which demonstrates the feasibility of making accurate in situ isotopic ratio measurements on Mars. This miniaturized instrument, with an optical path length of 10 cm should be capable of making accurate C-13/C-12 and N-15/N-14 measurements. Gas samples for measurement are to be produced by pyrolysis using soil samples as small as 50 mg. Measurements of C-13/C-12, O-18/O-16 and N-15/N-14 have been made to a precision of better than 0.1%, and various other isotopes are feasible. This laser technique, which relies on the extremely narrow emission linewidth of tunable diode lasers (less than 0.001/ cm),has favorable features in comparison to mass spectrometry, the standard method of accurate isotopic ratio measurement. The miniature instrument could be ready to deploy c 2003 or other Mars lander missions.

  9. Stable Isotopic Signatures of CO Uptake and Emission by Soil

    NASA Astrophysics Data System (ADS)

    Popa, E.; Röckmann, T.

    2015-12-01

    CO is important for atmospheric chemistry, is a pollutant, and it has been recognized as an important indirect greenhouse gas. Globally, soil uptake is one of main sinks of CO. On local scale, soil can be either a net sink or a net source of CO, due to the fact that both consumption and production of CO take place in soil concomitantly. These two phenomena are independent: while the uptake is microbial, the production is from abiotic oxidation of organic matter. In order to determine the isotopic signature of the exchange of CO between soil and atmosphere, soil chamber experiments were performed at a forest site in the Netherlands. Flaks samples were filled from the soil chamber, and analyzed for the stable isotopes 13C and 18O using the high precision measurement facility at IMAU. We found that the uptake of CO by soil is associated with a small positive fractionation, i.e. the lighter CO is taken up faster. Although the soil at this site was a strong sink for CO, the isotopic data show that a small emission flux was also present in all cases. 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.

  10. 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

  11. 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

  12. Stable isotope dilution assays in mycotoxin analysis.

    PubMed

    Rychlik, Michael; Asam, Stefan

    2008-01-01

    The principle and applications of stable isotope dilution assays (SIDAs) in mycotoxin analysis are critically reviewed. The general section includes historical aspects of SIDAs, the prerequisites and limitations of the use of stable isotopically labelled internal standards, and possible calibration procedures. In the application section actual SIDAs for the analysis of trichothecenes, zearalenone, fumonisins, patulin, and ochratoxin A are presented. The syntheses and availability of labelled mycotoxins for use as internal standards is reviewed and specific advances in food analysis and toxicology are demonstrated. The review indicates that LC-MS applications, in particular, require the use of stable isotopically labelled standards to compensate for losses during clean-up and for discrimination due to ion suppression. As the commercial availability of these compounds continues to increase, SIDAs can be expected to find expanding use in mycotoxin analysis.

  13. Stable carbon isotope analysis of coprocessing materials

    SciTech Connect

    Lancet, M.S.; Winschel, R.A.; Burke, F.P.

    1991-01-01

    Consol R D is developing and demonstrating stable carbon isotope analysis as a method to quantitatively distinguish coal-derived and petroleum-derived carbon in products from coal/petroleum coprocessing. The approach taken is to develop the method, then demonstrate its application an authentic continuous-unit products. The experimental details used for stable carbon isotope analyses by the organization that performs most of those analyses under this contract are described. A method was developed previously under this contract to correct the carbon sourcing calculations performed from stable carbon isotope analyses for selective isotopic fractionation. The method relies on three assumptions. This quarter, a study was completed to define the sensitivity of the carbon sourcing results to errors in the assumptions. Carbon contents and carbon isotope ratios were determined for the available feeds and product fractions from HRI bench-scale coprocessing Run 238-10 (Texas lignite/Hondo vacuum still bottoms (VSB), Texas lignite/Cold Lake VSB and Westerholt coal/Cold Lake VSB). These data were used for carbon sourcing calculations and individual feedstock conversion calculations. A previously devised means for correcting for selective isotope fractionation was applied. 6 refs., 30 figs., 16 tabs.

  14. A stable isotope aridity index for terrestrial environments

    PubMed Central

    Levin, Naomi E.; Cerling, Thure E.; Passey, Benjamin H.; Harris, John M.; Ehleringer, James R.

    2006-01-01

    We use the oxygen isotopic composition of tooth enamel from multiple mammalian taxa across eastern Africa to present a proxy for aridity. Here we report tooth enamel δ18O values of 14 species from 18 locations and classify them according to their isotopic sensitivity to environmental aridity. The species are placed into two groups, evaporation sensitive (ES) and evaporation insensitive (EI). Tooth enamel δ18O values of ES animals increase with aridity, whereas the tooth enamel δ18O values of EI animals track local meteoric water δ18O values, demonstrating that bioapatite δ18O values of animals with different behaviors and physiologies record different aspects of the same environment. The enrichment between tooth enamel δ18O values of ES and EI animals records the degree of 18O enrichment between evaporated water (ingested water or body water) and source water, which increases with environmental aridity. Recognition of the ES–EI distinction creates the opportunity to use the 18O composition of bioapatite as an index of terrestrial aridity. PMID:16840554

  15. 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.

  16. Identifying drivers of leaf water and cellulose stable isotope enrichment in Eucalyptus in northern Australia.

    PubMed

    Munksgaard, N C; Cheesman, A W; English, N B; Zwart, C; Kahmen, A; Cernusak, L A

    2017-01-01

    Several previous studies have investigated the use of the stable hydrogen and oxygen isotope compositions in plant materials as indicators of palaeoclimate. However, accurate interpretation relies on a detailed understanding of both physiological and environmental drivers of the variations in isotopic enrichments that occur in leaf water and associated organic compounds. To progress this aim we measured δ(18)O and δ(2)H values in eucalypt leaf and stem water and δ(18)O values in leaf cellulose, along with the isotopic compositions of water vapour, across a north-eastern Australian aridity gradient. Here we compare observed leaf water enrichment, along with previously published enrichment data from a similar north Australian transect, to Craig-Gordon-modelled predictions of leaf water isotopic enrichment. Our investigation of model parameters shows that observed (18)O enrichment across the aridity gradients is dominated by the relationship between atmospheric and internal leaf water vapour pressure while (2)H enrichment is driven mainly by variation in the water vapour-source water isotopic disequilibrium. During exceptionally dry and hot conditions (RH < 21%, T > 37 °C) we observed strong deviations from Craig-Gordon predicted isotope enrichments caused by partial stomatal closure. The atmospheric-leaf vapour pressure relationship is also a strong predictor of the observed leaf cellulose δ(18)O values across one aridity gradient. Our finding supports a wider applicability of leaf cellulose δ(18)O composition as a climate proxy for atmospheric humidity conditions during the leaf growing season than previously documented.

  17. A first Late Glacial and Early Holocene coupled 18O and 2H biomarker isotope record from Gemuendener Maar, Germany

    NASA Astrophysics Data System (ADS)

    Zech, Michael; Bromm, Tobias; Hepp, Johannes; Benesch, Marianne; Sirocko, Frank; Glaser, Bruno; Zech, Roland

    2015-04-01

    During the last years, we developed a method for compound-specific d18O analyses of hemicellulose-derived sugars from plants, soils and sediment archives (Zech and Glaser, 2009; Zech et al., 2014). The coupling of respective d18O sugar results with d2H alkane results from paleosol and sediment climate archives proved to be a valuable innovative approach towards quantitative paleoclimate reconstruction (Hepp et al., 2014; Zech et al., 2013). Here we present a first coupled d18O sugar and d2H alkane biomarker record obtained for Late Glacial and Early Holocene sediments from the Gemuendener Maar in the Eifel, Germany. The d18O sugar biomarker record resembles the d18O ice core records of Greenland. The coupling with the d2H alkane biomarker results allows drawing further more quantitative paleocimate information in terms of (i) paleohumidity and (ii) d18O of paleoprecipitation.

  18. Controls on the Nitrogen and Oxygen Isotopic Composition (δ 15N, δ 18O, δ 17O) of Atmospheric Nitrate in Princeton, NJ

    NASA Astrophysics Data System (ADS)

    Hastings, M. G.; Malcolm, E.; Kaiser, J.; Sigman, D. M.

    2004-12-01

    The oxygen isotopic composition of atmospheric nitrate reflects the oxidative mechanisms that convert NOx to HNO3, while the nitrogen isotopic composition of atmospheric nitrate may reflect different NOx source signatures and/or fractionations related to NOx chemistry [Michalski et al., 2003; Hastings et al., 2003; Freyer et al., 1993]. New analysis techniques are capable of determining the 15N/14N, 18O/16O and 17O/16O isotope ratios in samples at the nanomolar level [Sigman et al., 2001; Casciotti et al., 2002; see Kaiser et al., session H38]. This allows for the analysis of short-term variations in the isotopes of HNO3 with the potential to diagnose causal relationships by comparing the isotopic data with other features of atmospheric deposition. The 15N/14N, 18O/16O and 17O/16O of nitrate were analyzed from precipitation samples collected on an event-basis in Princeton, NJ between December 2002 and 2003. The nitrate concentration in Princeton rain ranges from 2.5 to 99.7 μ M (mean=21.1 μ M, n=61), similar to that found in other urban areas of New Jersey by the National Atmospheric Deposition Program. The isotopes of nitrate fall in the wide range reported for various environments with the δ 15N ranging from -4.0 to 9.5‰ (vs. air), and the δ 18O and δ 17O ranging from 57.2 to 90.5‰ and 50.7 to 77.8‰ (vs. VSMOW), respectively. The correlation between nitrate and sulfate concentration (R2=0.66) and the lack of a relationship between these major ions and the isotopes of nitrate supports the conclusion that below cloud scavenging is not the dominant control on the isotopic variations observed. Seasonal variations are observed in both the nitrogen and oxygen isotopes of nitrate. Overall the δ 15N is not correlated with either δ 18O or δ 17O, although both the δ 15N and δ 18O average lowest in the summer and highest in the winter. δ 18O is highly correlated with δ 17O of nitrate with anomalous enrichment in 17O relative to 18O (Δ 17O ranges from 19

  19. 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

  20. Stable carbon isotope analysis of coprocessing materials

    SciTech Connect

    Lancet, M.S.; Winschel, R.A.; Burke, F.P.

    1991-01-01

    The purpose of obtaining stable carbon isotope analyses of coprocessing products is to determine the amount of coal (or petroleum) carbon that is present in any reaction product. This carbon-sourcing of distillate fractions, soluble resid, and insoluble organic matter, etc. is useful in modeling reactions, and evaluating synergistic effects if they exist.

  1. Stable carbon isotope analysis of coprocessing materials

    SciTech Connect

    Lancet, M.S.; Winschel, R.A.; Burke, F.P.

    1991-12-31

    The purpose of obtaining stable carbon isotope analyses of coprocessing products is to determine the amount of coal (or petroleum) carbon that is present in any reaction product. This carbon-sourcing of distillate fractions, soluble resid, and insoluble organic matter, etc. is useful in modeling reactions, and evaluating synergistic effects if they exist.

  2. 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

  3. 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

  4. 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

  5. Local vs. Regional Groundwater Flow Delineation from Stable Isotopes at Western North America Springs.

    PubMed

    Springer, Abraham E; Boldt, Elizabeth M; Junghans, Katie M

    2017-01-01

    The recharge location for many springs is unknown because they can be sourced from proximal, shallow, atmospheric sources or long-traveled, deep, regional aquifers. The stable isotope ((18) O and (2) H) geochemistry of springs water can provide cost-effective indications of relative flow path distance without the expense of drilling boreholes, conducting geophysical studies, or building groundwater flow models. Locally sourced springs generally have an isotopic signature similar to local precipitation for that region and elevation. Springs with a very different isotopic composition than local meteoric inputs likely have non-local recharge, representing a regional source. We tested this local vs. regional flow derived hypothesis with data from a new, large springs isotopic database from studies across Western North America in Arizona, Nevada, and Alberta. The combination of location-specific precipitation data with stable isotopic groundwater data provides an effective method for flow path determination at springs. We found springs in Arizona issue from a mix of regional and local recharge sources. These springs have a weak elevation trend across 1588 m of elevation where higher elevation springs are only slightly more depleted than low elevation springs with a δ(18) O variation of 5.9‰. Springs sampled in Nevada showed a strong elevation-isotope relationship with high-elevation sites discharging depleted waters and lower elevation springs issuing enriched waters; only a 2.6‰ difference exists in (18) O values over an elevation range of more than 1500 m. Alberta's springs are mostly sourced from local flow systems and show a moderate elevation trend of 1200 m, but the largest range in δ(18) O, 7.1‰.

  6. Stable carbon isotope analysis of coprocessing materials

    SciTech Connect

    Burke, F.P.; Winschel, R.A.; Lancet, M.S.

    1990-05-01

    Consol R D is developing and demonstrating stable carbon isotope analysis as a method quantitatively distinguish coal-derived and petroleum-derived carbon in products from coal/petroleum coprocessing. The approach taken is to develop the method, then demonstrate its application on authentic continuous-unit products. The significance of selective isotopic fractionation is being determined and, if necessary, corrections will be applied to account for it. Activities for this quarter include: method development -- investigation of selective fractionation. Three petroleum atmospheric still bottoms (ASBs) were separated by distillation and solubility fractionation to determine the homogeneity of the carbon isotope ratios of the separated fractions. These same three petroleum ASBs and three geographically distinct coals were pyrolyzed at 800{degree}F for 30 min and hydrogenated over a CoMo catalyst at 750{degree}F for 60 min to determine the effects of these treatments on the isotopic compositions of the produce fractions. Twelve coal liquefaction oils were analyzed for carbon isotope ratios. These oils were derived from subbituminous and bituminous coals from the first- and second-stage reactors in the thermal/catalytic and modes; validation and application, analysis. Carbon isotope analyses of samples from HRI bench unit coprocessing run 238-2 (Taiheiyo coal/Maya VSB) were analyzed. A method to correct for selective isotopic fractionation was developed and applied to the data. Five coprocessing samples were analyzed at the request of SRI International. 12 refs., 15 figs., 24 tabs.

  7. Chironomid δ 18O as a proxy for past lake water δ 18O: a Lateglacial record from Rotsee (Switzerland)

    NASA Astrophysics Data System (ADS)

    Verbruggen, F.; Heiri, O.; Reichart, G.-J.; Lotter, A. F.

    2010-08-01

    We explored whether the stable oxygen isotope composition (δ 18O) of fossil chironomid remains can be used to reconstruct past variations in lake water δ 18O from Lateglacial and early Holocene sediments from Rotsee (Switzerland). A sediment core from the former littoral zone of the lake was examined since it contained both high concentrations of chironomid remains and abundant authigenic carbonates and therefore allowed a direct comparison of chironomid δ 18O with values measured on bulk carbonates. Since carbonate particles adhering to chironomid remains potentially affect 18O measurements we tested two methods to chemically remove residual carbonates. Trials with isotopically heavy and light acid solutions indicated that treatment with hydrochloric acid promoted oxygen exchange between chironomid remains and the water used during pretreatment. In contrast, a buffered 2 M ammonium chloride (NH 4Cl) solution did not seem to affect chironomid δ 18O to a significant extent. Fossil chironomid δ 18O was analyzed for the Rotsee record both using standard palaeoecological methods and after pretreatment with NH 4Cl. Samples prepared using standard techniques showed a poor correlation with δ 18O of bulk carbonate ( r2 = 0.14) suggesting that carbonate contamination of the chironomid samples obscured the chironomid δ 18O signature. Samples pretreated with NH 4Cl correlated well with bulk carbonate δ 18O ( r2 = 0.67) and successfully tracked the well-known Lateglacial changes in δ 18O. Chironomid δ 18O indicated depleted lake water δ 18O during the Oldest Dryas period, the Aegelsee and Gerzensee Oscillations, and the Younger Dryas, whereas enriched δ 18O values were associated with sediments deposited during the Lateglacial interstadial and the early Holocene. Differences in the amplitude of variations in bulk carbonate and chironomid δ 18O are attributed to differential temperature effects on oxygen isotope fractionation during the formation of carbonates and

  8. Stable isotope composition of precipitation in the south and north slopes of Wushaoling Mountain, northwestern China

    NASA Astrophysics Data System (ADS)

    Zongxing, Li; Qi, Feng; Song, Yong; Wang, Q. J.; Yang, Jiao; Yongge, Li; Jianguo, Li; Xiaoyan, Guo

    2016-12-01

    A study of spatial and temporal variability of precipitation isotope composition on the southern and north slopes of Wushaoling Mountain was conducted in order to explore the processes influencing its evolution. The analysis indicated that the isotopic composition, the slopes and intercepts of Local Meteroic Water Lines, altitude gradients and temperature effect are higher on the north slope than those on the south slope. The d-excess showed an increase from lower to higher altitudes, and the altitude gradients changed with season. The correlation coefficients between δ18O and d-excess decreased with increasing altitude due to weakening sub-cloud evaporation. Westerly wind principally dominates Wushaoling Mountain, so the relatively negative stable isotope values observed are related to the long distance transportation of water vapor in spring and winter. In summer and autumn, the locally strong sub-cloud evaporation cause relatively higher δ18O and lower d-excess. The results suggested that the sub-cloud evaporation has enriched the δ18O composition by 23%, 23%, 32%, 42% and 29% in May, June, July, August and September, respectively. In some circumstances, δ18O and δD were depleted at the end of multi-days rainfall events due to the rainout process. In addition, monsoonal moisture caused some negative δ18O in summer when an enhanced cyclonic circulation had developed on Tibetan Plateau. The study enhances the knowledge of isotopic evolution of precipitation and provides a basis for further study of isotopic hydrology in arid regions.

  9. 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.

  10. 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

  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. 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.

  13. 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

  14. 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.

  15. A novel isotopic fractionation during dissolved oxygen consumption in mesopelagic waters inferred from observation and model simulation of dissolved oxygen δ18O in open oceanic regions

    NASA Astrophysics Data System (ADS)

    Nakayama, N.; Oka, A.; Gamo, T.

    2012-12-01

    Oxygen isotopic ratio (δ18O) of dissolved oxygen is a useful for bioactive tracer of the subsurface aphotic (mesopelagic) ocean since it varies nonlinearly related to oxygen consumption via stoichiometry of organic matter decomposition. Therefore, along with global circulation model (GCM), observed δ18O and their vertical/geographical distribution can be effectively used to quantitatively determine how marine biological and ocean physical processes contribute to varying dissolved oxygen (DO) concentration in the ocean, in particular mesopelagic zone where pronounced biological activity alters DO concentration significantly. In the central north Pacific Ocean and Indian Ocean, including Arabian Sea, one of the few regions in the open ocean which has oxygen minimum zone (OMZ, a layer with severely depleted DO), vertical profiles of DO and δ18O were observed. These observed data are compared with a GCM simulation in which a constant isotopic fractionation factor of DO by marine biological respiration and a fixed Redfield molar ratio between P and O are assumed. Even in the Arabian Sea OMZ, relationship between DO and δ18O was found to be similar to those observed in other open oceans, indicating that no specific oxygen consumption process occurred in the OMZ. Using the GCM model, we attempted to reproduce the observed overall relationship between DO and δ18O, but it failed when we adopted the previously reported isotopic fractionation factor: Discrepancy became larger when oxygen saturation level decreased, in particular in thermocline water (at 20% oxygen saturation level, modeled δ18O was heavier than observed values by +7‰). Sensitivity simulations with the GCM model revealed that (1) simply changing the intensity of oxygen consumption by respiration/organic matter decomposition nor physical processes (diffusion and/or advection) could explain the observed relationship between DO and δ18O, (2) applying a smaller isotopic fractionation for deep waters

  16. Drought signals in tree-ring stable oxygen isotope series of Qilian juniper from the arid northeastern Tibetan Plateau

    NASA Astrophysics Data System (ADS)

    Qin, Chun; Yang, Bao; Bräuning, Achim; Grießinger, Jussi; Wernicke, Jakob

    2015-02-01

    For the mechanistic understanding of hydroclimate variability, stable oxygen isotopic ratios (δ18O) of tree-ring α-cellulose can play a key role in paleoclimatic research. On the north-east Tibetan Plateau (TP), a region particularly sensitive to climate change, there exists a distinct lack of δ18O research in tree-ring archives. The few currently existing tree-ring δ18O chronologies were obtained by pooling the wood material from the same year from different trees prior to preparation and analysis. Although this method is time and cost efficient, it might impede the analysis of changes within the internal variability of oxygen isotope signals and a deeper understanding of the resulting climate reconstruction. We selected five Qilian juniper (Sabina przewalskii Kom.) trees covering the period 1951-2011 on the north-east TP to investigate the climate signals contained in stable oxygen isotopic composition records obtained using single tree analysis. Although the inter-series correlation between the five individual δ18O series indicates a highly significant relationship (mean r = 0.59, n = 59, p = 0.01), the five individual δ18O series show significantly differently mean values. We found significant negative correlations between drought/hydroclimatically triggered climate parameters (PDSI, precipitation) and each of the individual δ18O series. Spatial correlation maps indicate negative correlation of tree-ring δ18O and Indian Ocean sea surface temperatures, and inverse correlation patters of moisture conditions on the northern and southern TP. Our results provide a reference for future research on stable oxygen isotope/climate signals in the species S. przewalskii Kom..

  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. 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.

  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. Oxygen isotope evolution of the Lake Owyhee volcanic field, Oregon, and implications for low-δ18O magmas of the Snake River Plain - Yellowstone hotspot

    NASA Astrophysics Data System (ADS)

    Blum, T.; Kitajima, K.; Nakashima, D.; Valley, J. W.

    2013-12-01

    The Snake River Plain - Yellowstone (SRP-Y) hotspot trend is one of the largest known low-δ18O magmatic provinces, yet the timing and distribution of hydrothermal alteration relative to hotspot magmatism remains incompletely understood. Existing models for SRP-Y low-δ18O magma genesis differ regarding the timing of protolith alteration (e.g. Eocene vs. present), depth at which alteration occurs (e.g. 15 km vs. <5 km), and physical controls on the extent of alteration (e.g. caldera collapse, crustal scale fluid flow, etc.). We expand the existing oxygen isotope data set for zircon in the Lake Owyhee volcanic field (LOVF) of east central Oregon to further identify magmatic oxygen isotope trends within the field. These data offer insight into the timing of alteration and the extent of the greater SRP-Y low-δ18O province, as well as the conditions that generate large low-δ18O provinces. 16-14 Ma silicic volcanism in the LOVF is linked to the pre-14 Ma SRP-Y hotspot, with volcanism partially overlapping extension in the north-south trending Oregon-Idaho Graben (OIG). Ion microprobe analyses of zircons from 16 LOVF silicic lavas and tuffs reveal homogeneous zircons on both the single grain and hand sample scales: individual samples have 2 S.D. for δ18O ranging from 0.27 to 0.96‰ (SMOW), and sample averages ranging from 1.8 to 6.0‰, excluding texturally chaotic and/or porous zircons which have δ18O values as low as 0.0‰. All low-δ18O LOVF magmas, including the caldera-forming Tuff of Leslie Gulch and Tuff of Spring Creek, are confined to the OIG, although not all zircons from within the OIG have low δ18O values. The presence and sequence of low-δ18O magmas in the LOVF and adjacent central Snake River Plain (CSRP) cannot be explained by existing caldera subsidence or pre-hotspot source models. These data, however, combined with volumetrically limited low-δ18O material in the adjacent Idaho Batholith and Basin and Range, are consistent with low-δ18O magmas

  1. Winter Precipitation Isotope Gradients (δ18O) of the Contiguous USA and Their Relationship to the Pacific/North American (PNA) Pattern

    NASA Astrophysics Data System (ADS)

    Liu, Z.; Bowen, G. J.; Welker, J. M.

    2011-12-01

    This study investigates the synoptic-dynamic relationship between Pacific/North American (PNA) pattern and winter precipitation isotopes of the contiguous USA using 2-year (1990 and 1992) USNIP (the United States Network for Isotopes in Precipitation) dataset. We find that patterns in the spatial gradient of precipitation isotope values reflect the position of the polar jet stream and juxtaposition of air masses associated with variation in the PNA pattern. During the positive PNA winter, a southward shift of zones of steep δ18O gradients in the eastern USA coincides with southward displacement of the polar jet stream, which leads to a greater frequency of polar air masses and typically depleted δ18O values in the region. A coincident eastward shift in high-gradient zones in the western USA is related to more frequent penetration of tropical air masses, which in juxtaposition with polar air in the mid-continent leads to higher gradient values in the western region. Our findings highlight the importance of PNA pattern in determining spatial patterns of precipitation isotopes, with implications for interpretations of paleo-water isotope values and isotopic applications to study modern hydrological processes.

  2. Stable carbon isotope analysis of coprocessing materials

    SciTech Connect

    Winschel, R.A.; Lancet, M.S.; Burke, F.P.

    1990-07-01

    Consol R D is developing and demonstrating stable carbon isotope analysis as a method to quantitatively distinguish coal-derived and petroleum-derived carbon in products from coal/petroleum coprocessing. The approach taken is to develop the method, then demonstrate its application on authentic continuous-unit products. The significance of selective isotopic fractionation is being determined and, if necessary, corrections will be applied to account for it. Precision, accuracy and range of applicability are being defined. The value of accessory analytical techniques also is being assessed. The program is designed to address a substantial, demonstrated need of coprocessing research (both exploratory and development) for a technique to quantitatively distinguish the contributions of the individual coprocessing feedstocks to the various products. The carbon isotope technique currently is in routine use for other applications. Progress is discussed. 7 refs., 7 figs., 12 tabs.

  3. 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

  4. 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.

  5. 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

  6. 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

  7. Assessing the Amazon Basin Circulation with Stable Water Isotopes

    NASA Astrophysics Data System (ADS)

    McGuffie, K.; Henderson-Sellers, A.

    2004-05-01

    The isotopic abundances of Oxygen-18 (δ 18O) and Deuterium (δ D) over the Amazon are used to constrain simulations of the water cycle in this, the largest river basin in the world. Tracking the two stable but rare isotopes of water (1HD16O and 1H218O) makes it possible to trace Amazonian regional evaporative and condensation processes. This offers isotopic constraints on regional to global-scale atmospheric moisture budgets. Based on data in the Global Network on Isotopes in Precipitation (GNIP) database, we analyse the simulation of the land surface hydrology and water cycling. Temporal changes between 1965 and 2000 in stable water isotopic signatures in the Amazon have been used to evaluate global climate model (GCM) predictions revealing notable anomalies. For example, the differences in the wet season deuterium excess between Belem and Manaus are consistent with recent GCM simulations only if there has been a relative increase in evaporation from non-fractionating water sources over this period. Despite earlier predictions that land-use change signals would be found, late twentieth century data reveal no significant change in dry season isotopic characteristics. On the other hand, more recent isotopic data do show trends at stations in the Andes, where as much as 88% of the rainfall is thought to be derived from recycled moisture. At Izobamba the wet season depletions are enhanced (greater depletion) and the dry season ones decreased (less depletion). At Bogota only the wet months show statistically significant changes - also an enhancement. More depletion in the wet months is consistent with reductions in non-fractioning recycling such as through transpiration and in full re-evaporation of canopy-intercepted rainfall. These data might be linked to deforestation impacts. Results of GCM and simpler model simulations of the Amazon suggest that the recent stable isotope record is consistent with the predicted effects of forest removal, perhaps combined with

  8. Decadal patterns in δ18O of atmospheric CO2

    NASA Astrophysics Data System (ADS)

    Zakem, E.; White, J. W.

    2010-12-01

    The stable oxygen isotope 18O is unique to isotope ecology in that it links the hydrosphere to the carbon cycle. Since land biosphere fluxes are the dominant influences on 18O of atmospheric CO2, particularly on shorter times scales, analysis of atmospheric δ18O trends can provide useful insight into the terrestrial carbon cycle. The isotopic values imprinted by leaf water and soil water exchanges with CO2 out-compete those from ocean exchange, fossil fuel and biomass burning, and stratospheric reactions. The opposing isotopic imprints of photosynthesis and ecosystem respiration therefore control the majority of atmospheric 18O concentration. The resulting seasonal cycle in δ18O data of peaks during early summer, when photosynthesis dominates, and lows during early winter, when respiration dominates, has been clearly established. However, the reasons for the interannual variability of atmospheric 18O remain unknown. Studies have shown that the size and isotopic value of the “retrodiffusion” flux- the CO2 that enters and exits leaves without being fixed by photosynthesis- is a function of stomatal conductance, which is affected by the relative humidity in the surrounding atmosphere. We observe that data from numerous global sites shows a global decadal oscillation in δ18O, suggesting a climatological forcing. We compare decadal trends in δ18O with climate oscillations and the 11-year solar cycle, as well as relative humidity records, examining correlations and proposing associated mechanisms. Understanding the decadal patterns in atmospheric 18O of CO2 will shed light on global terrestrial carbon fluxes and the carbon-water interaction on decadal time scales, potentially helping to scale human versus natural impacts on this coupled system.

  9. Analysis of the hydrogen and oxygen stable isotope ratios of beverage waters without prior water extraction using isotope ratio infrared spectroscopy.

    PubMed

    Chesson, Lesley A; Bowen, Gabriel J; Ehleringer, James R

    2010-11-15

    Hydrogen (δ(2)H) and oxygen (δ(18)O) stable isotope analysis is useful when tracing the origin of water in beverages, but traditional analytical techniques are limited to pure or extracted waters. We measured the isotopic composition of extracted beverage water using both isotope ratio infrared spectroscopy (IRIS; specifically, wavelength-scanned cavity ring-down spectroscopy) and isotope ratio mass spectrometry (IRMS). We also analyzed beer, sodas, juices, and milk 'as is' using IRIS. For IRIS analysis, four sequential injections of each sample were measured and data were corrected for sample-to-sample memory using injections (a) 1-4, (b) 2-4, and (c) 3-4. The variation between δ(2)H and δ(18)O values calculated using the three correction methods was larger for unextracted (i.e., complex) beverages than for waters. The memory correction was smallest when using injections 3-4. Beverage water δ(2)H and δ(18)O values generally fit the Global Meteoric Water Line, with the exception of water from fruit juices. The beverage water stable isotope ratios measured using IRIS agreed well with the IRMS data and fit 1:1 lines, with the exception of sodas and juices (δ(2)H values) and beers (δ(18)O values). The δ(2)H and δ(18)O values of waters extracted from beer, soda, juice, and milk were correlated with complex beverage δ(2)H and δ(18)O values (r = 0.998 and 0.997, respectively) and generally fit 1:1 lines. We conclude that it is possible to analyze complex beverages, without water extraction, using IRIS although caution is needed when analyzing beverages containing sugars, which can clog the syringe and increase memory, or alcohol, a known spectral interference.

  10. 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.

  11. 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.

  12. 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

  13. 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.

  14. 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 ...

  15. 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.

  16. Stable isotope fractionation by thermal diffusion through partially molten wet and dry silicate rocks

    NASA Astrophysics Data System (ADS)

    Bindeman, I. N.; Lundstrom, C. C.; Bopp, C.; Huang, F.

    2013-03-01

    Water plays a fundamental role in affecting geochemical transport and physical properties of magmas. Here we show the previously undocumented behavior of water within partially molten silicate resting in a temperature gradient, producing O, Li and H isotope redistribution by thermal diffusion leading to enrichment of light isotopes at the hot end of the gradient. After weeks to months, fully molten as well as mostly crystalline portions of water-bearing experiments develop remarkably large isotope and chemical redistributions: up to 28‰ for δ18O, 144‰ for δD, and 18‰ for δ7Li. In contrast, long-term dry experiments develop smaller (˜5‰ δ18O) isotopic fractionations only in the hotter end where it is molten or partially molten. Isotope fractionation of oxygen is linearly related to temperature, and the magnitude of isotopic separation per °C is ˜2× larger for wet experiments than dry ones. We explain this by water de-polymerizing the silicate structure leading to a smaller size of diffusing SiOx fragments. The magnitude of isotope separation between the hot and cold ends for Li, Mg, Fe, O, and H isotopes increases linearly with ΔMheavy-light/Mlight. These relationships provide predictive tests for natural rocks and highlight the role of water in isotope and compositional redistribution during temperature gradient mediated processes. We discuss the implications to natural environments in which the lightest stable isotopes (H, Li, O) with the greatest ΔMheavy-light/Mlight and fastest diffusion coefficients are capable of achieving mass-dependent redistribution in a transient temperature gradient. These experiments underscore the importance of solution-reprecipitation in wet subsolidus systems and demonstrate that isotopic redistribution can be established ˜6 orders of magnitude quicker than by diffusion through a traditional silicate melt at higher temperature. This has important implications for timescales of natural isotope and chemical

  17. 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

  18. 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

  19. Stable isotope characteristics of precipitation of Pamba River basin, Kerala, India

    NASA Astrophysics Data System (ADS)

    Resmi, T. R.; Sudharma, K. V.; Hameed, A. Shahul

    2016-10-01

    Stable isotope composition of precipitation from Pamba River basin, Kerala, India, is evaluated to understand the role of spatial and temporal variations on rainwater isotope characteristics. Physiographically different locations in the basin showed strong spatial and temporal variations. δ 18O varied from -7.63 to -1.75 ‰ in the lowlands; from -9.32 to -1.94 ‰ in the midlands and from -11.6 to -4.00 ‰ in the highlands. Local Meteoric Water Lines (LMWL) for the three regions were determined separately and an overall LMWL for the whole of the basin was found to be δ 2H = 6.6 (±0.4) δ 18 O+10.4 (±2.0). Altitude effect was evident for the basin (0.1 ‰ for δ 18O and 0.8 ‰ for δ 2H per 100 m elevation), while the amount effect was weak. The precipitation formed from the marine moisture supplied at a steady rate, without much isotopic evolution in this period may have masked the possible depletion of heavier isotopes with increasing rainfall. Consistently high d-excess values showed the influence of recycled vapour, despite the prevailing high relative humidity. The oceanic and continental vapour source origins for the south-west and north-east monsoons were clearly noted in the precipitation in the basin. Rayleigh distillation model showed about 30% rainout of the monsoon vapour mass in the basin.

  20. 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.

  1. 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.

  2. 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

  3. 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

  4. Carbonate clumped isotope paleothermometry and stable isotope results from the Eocene Fenghuo Shan Group, Hoh Xil Basin, Central Tibet

    NASA Astrophysics Data System (ADS)

    Snell, K. E.; Lippert, P. C.; Eiler, J. M.

    2009-12-01

    reconstructed soil water δ18O values range from 1.7 to 3.3‰ and have a trend of 0.3‰/°C. The reconstructed spar water δ18O value, in contrast, falls on the trend of the reconstructed cement waters, which suggests the spar calcite formed in equilibrium with the same water from which the cement precipitated. These data present strong evidence that the stable isotope record of carbonate in this section reflects a combination of primary (i.e., depositional) and secondary (i.e., diagenetic and burial metamorphic) processes. At maximum, these data suggest surface temperature during development of the paleosols was ~40°C or less during some part of the year, and ~25°C or less at the surface some time after deposition, during precipitation of the cement. At minimum, these preliminary data suggest that constrained surface temperatures require more detailed information regarding the burial history of the section and timing of cementation. Therefore attempts to determine the paleoelevation of this region from δ18O of carbonate will require careful documentation of extents of burial over-printing to identify and characterize the best-preserved materials.

  5. 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.

  6. 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

  7. Stables isotopes in submarine explosive volcanism

    NASA Astrophysics Data System (ADS)

    Pineau, F.; Shilobreeva, S.; Hekinian, R.; Bideau, D.; Javoy, M.

    2003-04-01

    The carbon and water contents and the corresponding isotopic compositions have been measured on a set of glassy samples collected by dives on the Mid-Atlantic Ridge (MAR) near 34^o50'N where volcanoclastic deposits are present. The volatile phases have been extracted by crushing under vacuum and step heating up to fusion. The δ18O of the glasses have been measured and it is shown that N-MORB are depleted in 18O (down to 5.2 ppm) whereas all the other lavas fall in the mantle range, 5.4 to 5.8 ppm. These data preclude strong interaction between seawater and magmas before eruption. The post-eruptive contents of dissolved water and carbon measured on N, T, E MORB and alkalic rocks range from 1125 up to 5253 ppm and from 20 up to 119 ppm respectively. The vesicle gas is dominated by CO_2 in N- and T-MORB. Water is very scarce in E-MORB vesicles but represents up to 17 vol% of the total gas in alkali-basalt vesicles. The pre-eruptive water and carbon concentrations of these magmas have been.They range from 1130 up to 8497 for water and from 343 up to 15677 ppm for carbon. The isotopic data demonstrate that seawater contamination is significant only in samples where most vesicles have been disrupted during eruption and quenching. Otherwise, all the δ13C and δD values of the volatiles phases expressed in vesicles or dissolved in glasses, fall in a typical mantle range, -4 to -7 ppm and -60 to -88 ppm, respectively. Degassing conditions were close to chemical equilibrium in the vesicle-rich samples (E- MORB and alkali-basalt) but kinetic fractionation occured during the last eruptive event, indicating that the enriched magmas travelled very fast impeding the attainment of isotopic equilibrium. Taking into account the crystal fractionation of the magmas, the primitive magmas had initial concentrations of water ranging from 1100 to 8000 ppm. The water-enriched magmas reached water saturation at about 1.5 km below the seafloor. Because of the important CO_2 degassing (80

  8. [Relationships between stable isotopes in precipitation in Wolong and monsoon activity].

    PubMed

    Xu, Zhen; Liu, Yu-hong; Wang, Zhong-sheng; Cui, Jun; Xu, Qing; An, Shu-qing; Liu, Shi-rong

    2008-04-01

    Stable isotopic analyses with precipitation, air temperature, wind direction and wind speed were performed in the Wolong Nature Reserve from July, 2003 to July, 2004. Results showed that d-excess values were (8.4 +/- 7.4) per thousand, (- 7.4 +/- 12.5) per thousand and (12.5 +/- 12.1) per thousand in precipitation events from April to August, September to October and November to March, respectively. Stable isotopic characteristics and d-excess values indicated that precipitation was mainly brought by the East Asia monsoon from ocean surface moisture from April to August, by the Indian summer monsoon from ocean moisture which extremely affected by rainout (strong depletion of heavy isotope) from September to October, and by Westerly from inland evaporation and local evaporation from November to March. Significant negative correlations between isotopic values and precipitation, which was amount effect, were found from April to October (r = - 0.389 for deltaD and r = - 0.380 for delta18O, p < 0.05, respectively) . Temperature effect also might affect isotopic values in precipitation (p < or = 0.10). During the active period of the East Asia monsoon and the Indian summer monsoon, stable isotopes in precipitation events had significant negative correlations with south wind index (r = - 0.354 for deltaD and r = - 0.390 for delta18O, p < 0.05, respectively), indicating that isotopic values closely associated with the origin and transport of moisture, and especially the Indian summer monsoon could bring vapors with very low isotopic values and d-excess values.

  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. 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.

  11. 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.

  12. Using Stable Isotope Ratio Analysis to Distinguish Perchlorate Sources

    DTIC Science & Technology

    2011-03-30

    Desert - natural nitrogen fertilizer 2. Mineral deposits – Death Valley, CA 3. Southwest soils and groundwater B. Other Anthropogenic 1. Fireworks 2...Herbicides Gunpowder Fireworks Road Flares Taiwanese Natural (Chile)  3 7 C l ( p e r m i l ) 18O (per mil) Forensic Isotopic Analysis: Chilean vs

  13. Stable carbon isotope analysis of coprocessing materials

    SciTech Connect

    Lancet, M.S.; Winschel, R.A.; Burke, F.P.

    1991-02-01

    Consol R D is developing and demonstrating stable carbon isotope analysis as a method to quantitatively distinguish coal-derived and petroleum-derived carbon in products from coal/petroleum coprocessing. The approach taken is develop the method, then demonstrate its application on authentic continuous-unit products. The significance of selective isotopic fractionation is being determined and, when necessary, corrections are applied to account for it. Precision, accuracy and range of applicability are being defined. The value of accessory analytical techniques also is being assessed. Previously reported data on samples from HRI bench-scale coprocessing Runs 227-53 (Texas lignite/Maya ASB and Texas lignite/Maya VSB) and 238-1 (Westerholt coal/Cold Lake VSB) were corrected for selective isotopic fractionation. Carbon sourcing was performed on samples from HRI bench-scale coprocessing Run 227-60 (Texas lignite/Maya VSB) and samples from UOP bench-scale coprocessing Run 26 (Illinois 6 coal/Lloydminster vacuum resid); the latter data were corrected for isotopic fractionation, though the former could not be corrected. A paper presented at the 1990 DOE Direct Liquefaction Contractor's Review Meeting is appended. 15 refs., 21 figs., 22 tabs.

  14. Stable isotopic characteristic of Taiwan's precipitation: A case study of western Pacific monsoon region

    NASA Astrophysics Data System (ADS)

    Peng, Tsung-Ren; Wang, Chung-Ho; Huang, Chi-Chao; Fei, Li-Yuan; Chen, Chen-Tung Arthur; Hwong, Jeen-Lian

    2010-01-01

    The stable oxygen and hydrogen isotopic features of precipitation in Taiwan, an island located at the western Pacific monsoon area, are presented from nearly 3,500 samples collected during the past decade for 20 stations. Results demonstrate that moisture sources from diverse air masses with different isotopic signals are the main parameter in controlling the precipitation's isotope characteristics. The air mass from polar continental (Pc) region contributes the precipitation with high deuterium excess values (up to 23‰) and relatively enriched isotope compositions (e.g., - 3.2‰ for δ 18O) during the winter with prevailing northeasterly monsoon. By contrast, air masses from equatorial maritime (Em) and tropical maritime (Tm) supply the precipitation with low deuterium excess values (as low as about 7‰) and more depleted isotope values (e.g., - 8.9‰ and - 6.0‰ for δ 18O of Tm and Em, respectively) during the summer with prevailing southwesterly monsoon. Thus seasonal differences in terms of δ 18O, δD, and deuterium excess values are primarily influenced by the interactions among various precipitation sources. While these various air masses travel through Taiwan, secondary evaporation effects further modify the isotope characteristics of the inland precipitation, such as raindrop evaporation (reduces the deuterium excess of winter precipitation) and moisture recycling (increases the deuterium excess of summer precipitation). The semi-quantitative estimations in terms of evaluation for changes in the deuterium excess suggest that the raindrop evaporation fractions for winter precipitation range 7% to 15% and the proportions of recycling moisture in summer precipitation are less than 5%. Additionally, the isotopic altitude gradient in terms of δ 18O for summer precipitation is - 0.22‰/100 m, greater than - 0.17‰/100 m of winter precipitation. The greater isotopic gradient in summer can be attributed to a higher temperature vs. altitude gradient

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

    USGS Publications Warehouse

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

    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.

  16. 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

  17. 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.

  18. 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.

  19. 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.

  20. 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

  1. 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.

  2. Controls on the stable isotopes in precipitation and surface waters across the southeastern Tibetan Plateau

    NASA Astrophysics Data System (ADS)

    Ren, Wei; Yao, Tandong; Xie, Shiyou; He, You

    2017-02-01

    Constraining temporal and spatial variability in water stable isotopes18O and δD) is requested for interpreting proxy records of paleoclimate/paleoaltimetry. The southeastern Tibetan Plateau (TP) receives large amounts of precipitation in both summer (JJAS) and spring (MAM) and this makes it different from most other parts of the TP where annual precipitation concentrates only in summer. However, our knowledge of controls on precipitation and surface runoff generation in this region is still far from sufficient. In this study, the δ18O and δD of precipitation and stream waters across the southeastern TP were analyzed to investigate moisture sources and empirical isotope-elevation relationships. Herein, seasonal precipitation patterns, moisture trajectories and precipitation isotopes suggest this region is seasonally dominated by the monsoon in summer and the southerlies (from the Bay of Bengal) or a mix of southerlies and westerlies in spring. Spatially, vertical variations in precipitation seasonality exert profound influences on isotopic variability for stream waters. Larger contributions of spring precipitation (with higher δ18O and d-excess (d-excess = δD-8δ18O) compared to summer precipitation) vs. summer precipitation in the surface runoff generation at lower elevations account for the uncommon altitudinal decrease in streamwater d-excess. Such a cause also contributes to the slightly greater vertical lapse rates of streamwater δ18O (-0.28 to -0.48‰/100 m) relative to the Himalayan front. In addition, although a robust δ18O-elevation relationship is demonstrated based upon our measured and other published data on a broad spatial scale (over a 5200 m elevation range), this relationship is found to deviate from the empirical/theoretical pattern in the Himalayan front, which is also caused by the substantial spring precipitation in the southeastern TP. It is suggested that long-term changes in δ18O or δD of paleowater in this region actually

  3. 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.

  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. Effect of thermal decarbonation on the stable isotope composition of carbonates

    SciTech Connect

    Durakiewicz, T.; Sharp, Z. D.; Papike, J. J. ,

    2001-01-01

    The unusual texture and stable isotope variability of carbonates in AH84001 have been used as evidence for early life on Mars (Romanek et al., 1994; McKay et al., 1996). Oxygen and carbon isotope variability is most commonly attributed to low-temperature processes, including Rayleigh-like fractionation associated with biological activity. Another possible explanation for the isotopic variability in meteoritic samples is thermal decarbonation. In this report, different carbonates were heated in a He-stream until decomposition temperatures were reached. The oxygen and carbon isotope ratios ({delta}{sup 18}O and {delta}{sup 13}C values) of the resulting gas were measured on a continuous flow isotope ratio mass spectrometer. The aim of this work is to evaluate the possibility that large isotopic variations can be generated on a small scale abiogenically, by the process of thermal decarbonation. Oxygen isotope fractionations of >4{per_thousand} have been measured during decarbonation of calcite at high temperatures (McCrea, 1950), and in excess of 6{per_thousand} for dolomite decarbonated between 500 and 600 C (Sharma and Clayton, 1965). Isotopic fractionations of this magnitude, coupled with Rayleigh-like distillation behavior could result in very large isotopic variations on a small scale. To test the idea, calcite, dolomite and siderite were heated in a quartz tube in a He-stream in excess of 1 atmosphere. Simultaneous determinations of {delta}{sup 13}C and {Delta}{sup 18}O values were obtained on 250 {micro}l aliquots of the CO{sub 2}-bearing He gas using an automated 6-way switching valve system (Finnigan MAT GasBench II) and a Finnigan MAT Delta Plus mass spectrometer. It was found that decarbonation of calcite in a He atmosphere begins at 720 C, but the rate significantly increases at temperatures of 820 C. After an initial light {delta}{sup 18}O value of -14.1{per_thousand} at 720 C associated with very early decarbonation, {delta}{sup 18}0 values increase to a

  6. 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

  7. 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

  8. 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.

  9. [Stable isotopes of carbon and nitrogen in soil ecological studies].

    PubMed

    Tiunov, A V

    2007-01-01

    The development of stable isotope techniques is one of the main methodological advances in ecology of the last decades of the 20th century. Many biogeochemical processes are accompanied by changes in the ratio between stable isotopes of carbon and nitrogen (12C/13C and 14N/15N), which allows different ecosystem components and different ecosystems to be distinguished by their isotopic composition. Analysis of isotopic composition makes it possible to trace matter and energy flows through biological systems and to evaluate the rate of many ecological processes. The main concepts and methods of stable isotope ecology and patterns of stable isotope fractionation during organic matter decomposition are considered with special emphasis on the fractionation of isotopes in food chains and the use of stable isotope studies of trophic relationships between soil animals in the field.

  10. Stable isotope compositions and water contents of boninite series volcanic rocks from Chichi-jima, Bonin Islands, Japan

    USGS Publications Warehouse

    Dobson, P.F.; O'Neil, J.R.

    1987-01-01

    Measurements of stable isotope compositions and water contents of boninite series volcanic rocks from the island of Chichi-jima, Bonin Islands, Japan, confirm that a large amount (1.6-2.4 wt.%) of primary water was present in these unusual magmas. An enrichment of 0.6??? in 18O during differentiation is explained by crystallization of 18O-depleted mafic phases. Silicic glasses have elevated ??18O values and relatively low ??D values indicating that they were modified by low-temperature alteration and hydration processes. Mafic glasses, on the other hand, have for the most part retained their primary isotopic signatures since Eocene time. Primary ??D values of -53 for boninite glasses are higher than those of MORB and suggest that the water was derived from subducted oceanic lithosphere. ?? 1987.

  11. Combining stable isotope and eddy covariance measurements to investigate carbon exchanges between the atmosphere and a tallgrass prairie

    NASA Astrophysics Data System (ADS)

    Lai, C.; Schauer, A.; Owensby, C.; Ham, J.; Ehleringer, J.

    2002-12-01

    Stable isotope ratios of various ecosystem components were measured in a C4-dominated tallgrass prairie with co-existing eddy covariance system near Manhattan, Kansas. The carbon and oxygen isotope compositions of nighttime atmospheric CO2 were measured weekly since early spring of 2002. In May and July, δ18O of water vapor, leaf and stem water of three major species were measured every 3-4 hours for 2-3 consecutive days. The δ18O of precipitation and soil water, δ13C of whole plant, litter and soil organic matter were also measured during these intensive field campaigns. Preliminary results from stable isotope analyses revealed apparent diurnal cycles in the δ18O of leaf water (δ18Oleaf). The Craig-Gordon model was shown capable of predicting the mean δ18Oleaf of dominant species. The carbon isotope ratios of ecosystem respiration vary by nearly 10 per mil for the 2002 growing season, reflecting the seasonality of C3-C4 dominance. Prior to our July experiment, the region experienced a severe drought. The eddy covariance measurements indicate a substantial mid-day decline in the photosynthetic uptake presumably due to high air temperature and vapor pressure deficit in this period. Details on using stable isotope and flux measurements to partition net ecosystem exchange into photosynthetic and respiratory fluxes are discussed for this grassland ecosystem.

  12. 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...

  13. Oxygen isotope evolution of the Lake Owyhee volcanic field, Oregon, and implications for the low-δ18O magmatism of the Snake River Plain-Yellowstone hotspot and other low-δ18O large igneous provinces

    NASA Astrophysics Data System (ADS)

    Blum, Tyler B.; Kitajima, Kouki; Nakashima, Daisuke; Strickland, Ariel; Spicuzza, Michael J.; Valley, John W.

    2016-11-01

    The Snake River Plain-Yellowstone (SRP-Y) hotspot track represents the largest known low-δ18O igneous province; however, debate persists regarding the timing and distribution of meteoric hydrothermal alteration and subsequent melting/assimilation relative to hotspot magmatism. To further constrain alteration relations for SRP-Y low-δ18O magmatism, we present in situ δ18O and U-Pb analyses of zircon, and laser fluorination δ18O analyses of phenocrysts, from the Lake Owyhee volcanic field (LOVF) of east-central Oregon. U-Pb data place LOVF magmatism between 16.3 and 15.4 Ma, and contain no evidence for xenocrystic zircon. LOVF δ18O(Zrc) values demonstrate (1) both low-δ18O and high-δ18O caldera-forming and pre-/post-caldera magmas, (2) relative increases in δ18O between low-δ18O caldera-forming and post-caldera units, and (3) low-δ18O magmatism associated with extension of the Oregon-Idaho Graben. The new data, along with new compilations of (1) in situ zircon δ18O data for the SRP-Y, and (2) regional δ18O(WR) and δ18O(magma) patterns, further constrain the thermal and structural associations for hydrothermal alteration in the SRP-Y. Models for low-δ18O magmatism must be compatible with (1) δ18O(magma) trends within individual SRP-Y eruptive centers, (2) along axis trends in δ18O(magma), and (3) the high concentration of low-δ18O magmas relative to the surrounding regions. When considered with the structural and thermal evolution of the SRP-Y, these constraints support low-δ18O magma genesis originating from syn-hotspot meteoric hydrothermal alteration, driven by hotspot-derived thermal fluxes superimposed on extensional tectonics. This model is not restricted to continental hotspot settings and may apply to several other low-δ18O igneous provinces with similar thermal and structural associations.

  14. Legacy of contaminant N sources to the NO3‑ signature in rivers: a combined isotopic (δ15N-NO3‑, δ18O-NO3‑, δ11B) and microbiological investigation

    NASA Astrophysics Data System (ADS)

    Briand, Cyrielle; Sebilo, Mathieu; Louvat, Pascale; Chesnot, Thierry; Vaury, Véronique; Schneider, Maude; Plagnes, Valérie

    2017-02-01

    Nitrate content of surface waters results from complex mixing of multiple sources, whose signatures can be modified through N reactions occurring within the different compartments of the whole catchment. Despite this complexity, the determination of nitrate origin is the first and crucial step for water resource preservation. Here, for the first time, we combined at the catchment scale stable isotopic tracers (δ15N and δ18O of nitrate and δ11B) and fecal indicators to trace nitrate sources and pathways to the stream. We tested this approach on two rivers in an agricultural region of SW France. Boron isotopic ratios evidenced inflow from anthropogenic waters, microbiological markers revealed organic contaminations from both human and animal wastes. Nitrate δ15N and δ18O traced inputs from the surface leaching during high flow events and from the subsurface drainage in base flow regime. They also showed that denitrification occurred within the soils before reaching the rivers. Furthermore, this study highlighted the determinant role of the soil compartment in nitrate formation and recycling with important spatial heterogeneity and temporal variability.

  15. Legacy of contaminant N sources to the NO3− signature in rivers: a combined isotopic (δ15N-NO3−, δ18O-NO3−, δ11B) and microbiological investigation

    PubMed Central

    Briand, Cyrielle; Sebilo, Mathieu; Louvat, Pascale; Chesnot, Thierry; Vaury, Véronique; Schneider, Maude; Plagnes, Valérie

    2017-01-01

    Nitrate content of surface waters results from complex mixing of multiple sources, whose signatures can be modified through N reactions occurring within the different compartments of the whole catchment. Despite this complexity, the determination of nitrate origin is the first and crucial step for water resource preservation. Here, for the first time, we combined at the catchment scale stable isotopic tracers (δ15N and δ18O of nitrate and δ11B) and fecal indicators to trace nitrate sources and pathways to the stream. We tested this approach on two rivers in an agricultural region of SW France. Boron isotopic ratios evidenced inflow from anthropogenic waters, microbiological markers revealed organic contaminations from both human and animal wastes. Nitrate δ15N and δ18O traced inputs from the surface leaching during high flow events and from the subsurface drainage in base flow regime. They also showed that denitrification occurred within the soils before reaching the rivers. Furthermore, this study highlighted the determinant role of the soil compartment in nitrate formation and recycling with important spatial heterogeneity and temporal variability. PMID:28150819

  16. Planktic Foraminiferal Turnover and Stable Isotope Stratigraphy Across OAE1B in the Subtropical North Atlantic

    NASA Astrophysics Data System (ADS)

    Huber, B. T.; Price, N. A.; MacLeod, K. G.

    2003-12-01

    Stable isotope data generated from glassy (diagenetically unaltered) foraminifera from the subtropical North Atlantic (ODP Site 1049) reveal abrupt paleoceanographic and faunal changes that coincide with the Aptian/Albian boundary and the onset of Oceanic Anoxic Event (OAE) 1b. At least three planktic and one benthic species per sample, selected at closely spaced intervals from the Globigerinelloides algerianus Zone (mid-Aptian) through uppermost Ticinella bejaouaensis Zone (uppermost Aptian), reveal a consistently low (<1.1‰ ) vertical δ 18O gradient, suggesting that the thermocline was weakly developed throughout this time. Benthic δ 18O values show a slight positive increase from +0.5 ‰ during the mid-Aptian to +1.1% during the latest Aptian, then decrease to -0.2‰ during peak Corg deposition in OAE 1b (Hedbergella rischi Zone, lowermost Albian). Assuming that the δ 18O composition of Cretaceous seawater averaged -1.2‰ and polar ice sheets were absent or very small, we estimate that middle bathyal waters at this site ranged from 7-9° C during the mid-late Aptian and warmed to 12° C during OAE 1b peak Corg deposition. Mid-late Aptian upper surface waters ranged from 11-12° C, then warmed to 20° C during OAE 1b. The simultaneous change in planktic foraminifer assemblages and stable isotope values indicates that the onset of OAE 1b involved major changes in the North Atlantic climate and oceanography.

  17. 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.

  18. 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

  19. 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

  20. Uncertainty in source partitioning using stable isotopes.

    PubMed

    Phillips, D L; Gregg, J W

    2001-04-01

    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, or C3 and C4 plant inputs to soil organic carbon. Linear mixing models can be used to partition two sources with a single isotopic signature (e.g., δ(13)C) or three sources with a second isotopic signature (e.g., δ(15)N). Although variability of source and mixture signatures is often reported, confidence interval calculations for source proportions typically use only the mixture variability. We provide examples showing that omission of source variability can lead to underestimation of the variability of source proportion estimates. For both two- and three-source mixing models, we present formulas for calculating variances, standard errors (SE), and confidence intervals for source proportion estimates that account for the observed variability in the isotopic signatures for the sources as well as the mixture. We then performed sensitivity analyses to assess the relative importance of: (1) the isotopic signature difference between the sources, (2) isotopic signature standard deviations (SD) in the source and mixture populations, (3) sample size, (4) analytical SD, and (5) the evenness of the source proportions, for determining the variability (SE) of source proportion estimates. The proportion SEs varied inversely with the signature difference between sources, so doubling the source difference from 2‰ to 4‰ reduced the SEs by half. Source and mixture signature SDs had a substantial linear effect on source proportion SEs. However, the population variability of the sources and the mixture are fixed and the sampling error component can be changed only by increasing sample size. Source proportion SEs varied inversely with the square root of sample size, so an increase from 1 to 4 samples per population cut the SE in half. Analytical SD had little effect over the range examined since it was generally

  1. 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.

  2. 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

  3. 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

    2014-03-07

    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.

  4. The stable isotope geochemistry of volcanic lakes, with examples from Indonesia

    NASA Astrophysics Data System (ADS)

    Varekamp, J. C.; Kreulen, R.

    2000-04-01

    Stable isotope compositions ( δD, δ18O and δ34S) of volcanic lake waters, gas condensates and spring waters from Indonesia, Italy, Japan, and Russia were measured. The spring fluids and gas samples plot in a broad array between meteoric waters and local high-temperature volcanic gas compositions. The δD and δ18O data from volcanic lakes in East Indonesia plot in a concave band ranging from local meteoric waters to evaporated fluids to waters heavier than local high-temperature volcanic gases. We investigated isotopic fractionation processes in volcanic lakes at elevated temperatures with simultaneous mixing of meteoric waters and volcanic gases. An elevated lake water temperature gives enhanced kinetic isotope fractionation and changes in equilibrium fractionation factors, providing relatively flat isotope evolution curves in δ18O- δD diagrams. A numerical simulation model is used to derive the timescales of isotopic evolution of crater lakes as a function of atmospheric parameters, lake water temperature and fluxes of meteoric water, volcanic gas input, evaporation, and seepage losses. The same model is used to derive the flux magnitude of the Keli Mutu lakes in Indonesia. The calculated volcanic gas fluxes are of the same order as those derived from energy budget models or direct gas flux measurements in open craters (several 100 m 3 volcanic water/day) and indicate a water residence time of 1-2 decades. The δ34S data from the Keli Mutu lakes show a much wider range than those from gases and springs, which is probably related to the precipitation of sulfur in these acid brine lakes. The isotopic mass balance and S/Cl values suggest that about half of the sulfur input in the hottest Keli Mutu lake is converted into native sulfur.

  5. 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.

  6. 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.

  7. 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

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

    PubMed

    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

  9. 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

  10. [Fractionation of hydrogen stable isotopes in the human body].

    PubMed

    Siniak, Iu E; Grigor'ev, A I; Skuratov, V M; Ivanova, S M; Pokrovskiĭ, B G

    2006-01-01

    Fractionation of hydrogen stable isotopes was studied in 9 human subjects in a chamber with normal air pressure imitating a space cabin. Mass-spectrometry of isotopes in blood, urine, saliva, and potable water evidenced increases in the contents of heavy H isotope (deuterium) in the body liquids as compared with water. These results support one of the theories according to which the human organism eliminates heavy stable isotopes of biogenous chemical elements.

  11. Equatorial Pacific ``stable isotope reference curve'' for the Oligocene

    NASA Astrophysics Data System (ADS)

    Pälike, H.; Norris, R.; Herle, J. O.; Wilson, P. A.; Lear, C. H.; Coxall, H. K.; Tripati, A. K.

    2005-12-01

    We present an uninterrupted chronology of climate and ocean carbon chemistry from ODP Site 1218 recovered in the equatorial Pacific, from the Eocene / Oligocene to the Oligocene / Miocene boundary, ~34 to 23 Ma. Using astronomically age calibrated data we find a strong imprint of the 405, 127 and 96-thousand-year (kyr) Earth's eccentricity as well as a dominant influence of the 1.2 million year (Myr) obliquity amplitude modulation cycles on periodically re-occurring Oligocene glacial and carbon cycle events. In combination, these astronomical modulations act as the ``heartbeat'' of the Oligocene climate system. The response of the climate system to intricate orbital variations is striking and suggests a fundamental role of the carbon cycle in the interaction between solar forcing and climate. Our record provides a new high-resolution view of the Oligocene climate system, prompts a re-evaluation of the previously hypothesised late Oligocene deglaciation, and sheds new light on Oligocene inter-ocean isotope gradients. Salient observations include foraminiferal benthic stable oxygen and carbon isotopes that co-vary, a phase lag of δ13C w.r.t. δ18O for the 405 kyr cycle, preferential filtering of longer orbital periods in δ13C, presumably due to σCO2 reservoir buffering. We then use simple orbitally forced carbon cycle box models and manage to re-create the patterns observed in our data, including the overall strong amplitude of 405 kyr cycles in δ13C. Depending on ice-sheet presence and pCO2 concentrations, our model predicts re-occurring conditions favouring glaciations every 2.4 Myr, including the Eocene/Oligocene transition.

  12. Effect of NO2(-) on stable isotope fractionation during bacterial sulfate reduction.

    PubMed

    Einsiedl, Florian

    2009-01-01

    The effects of low NO2(-) concentrations on stable isotope fractionation during dissimilatory sulfate reduction by strain Desulfovibrio desulfuricans were investigated. Nitrite, formed as an intermediate during nitrification and denitrification processes in marine and freshwater habitats, inhibits the reduction of the sulfuroxy intermediate SO3(2-) to H2S even at low concentrations. To gain an understanding of the inhibition effect of the reduction of the sulfuroxy intermediate on stable isotope fractionation in sulfur and oxygen during bacterial sulfate reduction, nitrite was added in the form of short pulses. In the batch experiments that contained 0.02, 0.05, and 0.1 mM nitrite, sulfur enrichment factors epsilon of -12 +/- 1.6, -15 +/- 1.1, and -26 +/- 1.3 per thousand, respectively were observed. In the control experiment (no addition of nitrite) a sulfur enrichment factor epsilon of around -11 per thousand was calculated. In the experiments that contained no 18O enriched water (delta18O: -10 per thousand) and nitrite concentrations of 0.02, 0.05, and 0.1 mM, delta18O values in the remaining sulfate were fairly constant during the experiments (delta18O sulfate: approximately equal to 10 per thousand) and were similar to those obtained from the control experiment (no nitrite and no enriched water). However, in the batch experiments that contained 18O enriched water (+700 per thousand) and nitrite concentrations of 0.05 and 0.1 mM increasing delta18O values in the remaining sulfate from around 15 per thousand to approximately 65 and 85 per thousand, respectively, were found. Our experiments that contained isotopic enriched water and nitrite show clear evidence that the ratio of forward and backward fluxes regulated by adenosine-5'-phosphosulfate reductase (APSR) controls the extent of sulfur isotope fractionation during bacterial sulfate reduction in strain Desulfovibrio desulfuricans. Since the metabolic sulfuroxy intermediate SO3(2-) exchanges with water

  13. 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.

  14. 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.

  15. 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

  16. Stable Chlorine Isotopes in Ocean Crust Processes

    NASA Astrophysics Data System (ADS)

    Bach, W.; Layne, G.; Kent, A.

    2003-12-01

    shallow subduction zone. The depleted MORB mantle is believed to have a δ 37Cl between 4 and 7 ‰ , similar to C1-chondrite (Magenheim et al., 1995, EPSL, 131, 427). MORB with high Cl and Cl/K tend to have δ 37Cl close to 0 ‰ , which has been explained by contamination of basaltic magmas with seawater-derived Cl. However, the most evolved ferrobasalts and andesites from oceanic spreading ridges have negative δ 37Cl values, down to -1.7 ‰ (Magenheim, unpublished data). Together with data for oceanic gabbros, the δ 37Cl-[Cl] data for these highly evolved rocks form a trend that could be explained by an AFC-like process, although the fact that the trend extends to negative δ 37Cl values cannot be reconciled with batch mixing of magma and salt or brine. Rather, it indicates that 35Cl is preferentially incorporated into the magma and may be related to diffusive exchange between Cl in brine pools above the melt lens of an axial magma system. A more comprehensive global dataset as well as spot analyses of Cl isotope ratios by IMP-SIMS (e.g., of melt inclusions) and the combination of δ 37Cl with other stable isotope systems (B, Li, O, H) are required before these tentative models for global chlorine cycling and crustal assimilation at spreading ridges can be rigorously evaluated.

  17. 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.

  18. Stable Isotope Constraints on N Deposition and Cycling in Lake Tahoe

    NASA Astrophysics Data System (ADS)

    Michalski, G.; Young, R.; Thiemens, M.

    2004-12-01

    Oligotrophic Lake Tahoe has seen a decrease in opacity over the past 5 decades, which has been attributed to particulate matter (shoreline development) and algal growth (nutrients). The lake has also seen a shift from being nitrogen limited to phosphorous limited in the same time frame. Identifying the source of the increased nitrogen loading is essential for mitigation strategies to keep Lake Tahoe Blue - a 10 billion dollar watershed restoration campaign. Atmospheric deposition of nitric acid and nitrate aerosols (NO3-atm) is thought to be a significant source of new N to the lake surface. Quantifying the flux and fate of NO3-atm is limited by modeling estimates of deposition, utilization and re nitrification of organic N. Stable isotope tracers can help resolve these limitations. Δ 17O measurements, the δ 17O enrichment over the expected .52 δ 18O enrichment, have been shown to be a sensitive tracer of NO3-atm. Oxygen isotopic analysis of NO3-atm from the basin have shown Δ17O values of ~ 22‰ . Lake water nitrate have Δ17O values of 1-4‰ depending on depth and season, indicating that up to 20% of the lake nitrate is retained from the atmosphere. The δ 18O values (-2.0 to 12‰ ) cannot be used to estimate of the NO3-atm loading because of the wide range of δ 18O values associated with nitrification. Variations of Δ 17O with season can provide estimates of the flux of the nitrification of organic N. Balancing the isotopic budget with δ 15N and δ 18O measurements further constrains the N cycling dynamic within the lake. From these data a nutrient flux/utilization model can be developed.

  19. Historical and contemporary stable isotope tracer approaches to studying mammalian protein metabolism.

    PubMed

    Wilkinson, Daniel James

    2016-05-16

    Over a century ago, Frederick Soddy provided the first evidence for the existence of isotopes; elements that occupy the same position in the periodic table are essentially chemically identical but differ in mass due to a different number of neutrons within the atomic nucleus. Allied to the discovery of isotopes was the development of some of the first forms of mass spectrometers, driven forward by the Nobel laureates JJ Thomson and FW Aston, enabling the accurate separation, identification, and quantification of the relative abundance of these isotopes. As a result, within a few years, the number of known isotopes both stable and radioactive had greatly increased and there are now over 300 stable or radioisotopes presently known. Unknown at the time, however, was the potential utility of these isotopes within biological disciplines, it was soon discovered that these stable isotopes, particularly those of carbon ((13) C), nitrogen ((15) N), oxygen ((18) O), and hydrogen ((2) H) could be chemically introduced into organic compounds, such as fatty acids, amino acids, and sugars, and used to "trace" the metabolic fate of these compounds within biological systems. From this important breakthrough, the age of the isotope tracer was born. Over the following 80 yrs, stable isotopes would become a vital tool in not only the biological sciences, but also areas as diverse as forensics, geology, and art. This progress has been almost exclusively driven through the development of new and innovative mass spectrometry equipment from IRMS to GC-MS to LC-MS, which has allowed for the accurate quantitation of isotopic abundance within samples of complex matrices. This historical review details the development of stable isotope tracers as metabolic tools, with particular reference to their use in monitoring protein metabolism, highlighting the unique array of tools that are now available for the investigation of protein metabolism in vivo at a whole body down to a single protein

  20. 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.

  1. Stable isotopic signature of Australian monsoon controlled by regional convection

    NASA Astrophysics Data System (ADS)

    Zwart, C.; Munksgaard, N. C.; Kurita, N.; Bird, M. I.

    2016-11-01

    The aim of this study was to identify the main meteorological drivers of rainfall isotopic variation in north Australia in order to improve the interpretation of isotopic proxy records in this region. An intense monitoring program was conducted during two monsoonal events that showed significant and systematic isotopic change over time. The results showed a close link between isotopic variation in precipitation and variability in monsoon conditions, associated with the presence of large convective envelopes propagating through the study site. The largest negative amplitudes in the isotopic signal were observed when eastward and westward moving precipitation systems within the convective envelope merged over the measurement site. This suggests that the amplitude of the isotopic signal is related to the size and activity of the convective envelope. The strong correlation between rainfall isotopic variation, regional outgoing longwave radiation and regional rainfall amount supports this conclusion. This is further strengthened by the strong relationship between isotopic variation and the integrated rainfall history of air masses prior to arriving at the measurement locations. A local amount effect was not significant and these findings support the interpretation of δ18O as proxy for regional climatic conditions rather than local rainfall amount. Meteorological parameters that characterize intra-seasonal variability of monsoon conditions were also found to be strongly linked to inter-seasonal variability of the monthly based δ18O values in the Global Network of Isotopes in Precipitation (GNIP) database. This leads to the conclusion that information about the Australian monsoon variability can likely be inferred from the isotopic proxy record in North Australia on short (intra seasonal) and long (inter seasonal or longer) timescales.

  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. 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

  4. 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.

  5. 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.

  6. Principles and limitations of stable isotopes in differentiating organic and conventional foodstuffs: 2. Animal products.

    PubMed

    Inácio, Caio T; Chalk, Phillip M

    2017-01-02

    In this review, we examine the variation in stable isotope signatures of the lighter elements (δ(2)H, δ(13)C, δ(15)N, δ(18)O, and δ(34)S) of tissues and excreta of domesticated animals, the factors affecting the isotopic composition of animal tissues, and whether stable isotopes may be used to differentiate organic and conventional modes of animal husbandry. The main factors affecting the δ(13)C signatures of livestock are the C3/C4 composition of the diet, the relative digestibility of the diet components, metabolic turnover, tissue and compound specificity, growth rate, and animal age. δ(15)N signatures of sheep and cattle products have been related mainly to diet signatures, which are quite variable among farms and between years. Although few data exist, a minor influence in δ(15)N signatures of animal products was attributed to N losses at the farm level, whereas stocking rate showed divergent findings. Correlations between mode of production and δ(2)H and δ(18)O have not been established, and only in one case of an animal product was δ(34)S a satisfactory marker for mode of production. While many data exist on diet-tissue isotopic discrimination values among domesticated animals, there is a paucity of data that allow a direct and statistically verifiable comparison of the differences in the isotopic signatures of organically and conventionally grown animal products. The few comparisons are confined to beef, milk, and egg yolk, with no data for swine or lamb products. δ(13)C appears to be the most promising isotopic marker to differentiate organic and conventional production systems when maize (C4) is present in the conventional animal diet. However, δ(13)C may be unsuitable under tropical conditions, where C4 grasses are abundant, and where grass-based husbandry is predominant in both conventional and organic systems. Presently, there is no universal analytical method that can be applied to differentiate organic and conventional animal products.

  7. Diatom-inferred δ18O of a Bolivian paleolake during the last deglaciation (18.6-11.7 ka): impact of the paleolake evaporation and water recycling on the isotopic composition of Andean glaciers

    NASA Astrophysics Data System (ADS)

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

    2013-04-01

    During the last deglaciation, on the Bolivian Altiplano (~16°S), a wide paleolake covering at least 51,000 km2, named lake Tauca reached its maximum highstand between 16.5 and 15 ka. Overlooking this site, an ice-core from the Sajama ice-cap (covering the last 25,000 years) evidenced an oxygen 18 isotopic excursion of +7‰ matching with the end of the Tauca phase, and more pronounced by about +5‰ compared with the neighboring Andean ice-cores isotopic records. Here we i) provide a new and original experimental use of lacustrine diatoms (n=21) at medium resolution (~300 years) together with ostracods (n=4) for isotopic δ18O paleolake water reconstruction (δ18Olake), ii) detail a simple hydro-isotopical model with constraints given by literature to explain the strong features in the δ18Olake signal and iii) explore whether the Tauca paleolake could contribute as a moisture source to precipitation at Sajama site when it disappears at 14.2 ka. Based on a new chronostratigraphy, the sedimentary sections cover lake Tauca phase (~18.7-14.1 ka) and lake Coipasa phase (~12.6-11.7 ka). On centuries time scale, strong features consistently appear in δ18Olake: an abrupt decrease during lake filling phases immediately followed by an increase during lake level stable phases. The highest variation occurred at ~15.9 ka with a δ18Olake fall of about ~14‰ concomitant with lake Tauca highstand, and followed by a δ18Olake increase of a similar amplitude four centuries later. We also show that this unexpected re-enrichment of δ18Olake can be partly explained with a simple hydro-isotopic model, based on Craig and Gordon's model, with coherent constraints by a re-equilibration of isotopic fluxes in lake steady-state. Based on an evaporative lake model and a simple water stable isotopic balance between two potential moisture sources for Sajama precipitation (eastward advected moisture and lake evaporation), we show that total or partial (from 5 to 60%) evaporation of the lake

  8. 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.

  9. 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.

  10. 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

  11. 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...

  12. 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...

  13. 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.

  14. /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.

  15. Stable isotope customer list and summary of shipments, FY 1986

    SciTech Connect

    Tracy, J.G.

    1987-02-01

    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 indicating geographical concentrations of isotope users; and tabulation of the shipments, quantities, and dollars for domestic, foreign, and project categories for each isotope.

  16. 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

  17. 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 ...

  18. Characterization of Acid Mine Drainage Sources Using Stable and Radiogenic Isotopes, Chalk Creek, Colorado

    NASA Astrophysics Data System (ADS)

    Cordalis, D.; Michel, R.; Williams, M.; Wireman, M.

    2003-12-01

    Acid mine drainage (AMD) affects many streams throughout the western United States. Understanding flow dynamics and sources within a fractured rock setting is necessary in outlining a potential remediation strategy for AMD. Radiogenic and stable isotopes of water were used in the Mary Murphy Mine, Chalk Creek, Colorado, in order to characterize flowpaths and sourcewaters. By delineating the sources of the mine water, groundwater, and event water, we may be able to target remediation techniques for individual contamination sources. Moreover, results from this research provide insights into groundwater flow systems in mountain environments of the Colorado Rockies. Tritium, a cosmogenic isotope of hydrogen, has a half-life 12.43y and is useful for studying hydrologic processes at the decadal time scale and can be used as an effective tracer when traditional chemical tracers are non-conservative. Hydrometric information showed that discharge from the mine adit exhibited a hydrograph characteristic of snowmelt runoff. However, mixing models using stable water isotopes (D and 18O) found less than 7% of the mine's peak discharge was from snowmelt, suggesting a regional groundwater dominated system. Mine interior samples fell into two characteristic groupings: either from the extreme north side of the drift which contained most of the zinc contamination, and all other locations. The waters from the north drift, MVN-3 and MVN-4, had lower 18O values, -17.62 per mil and -17.17 per mil, respectively, than did any of the other locations, suggesting a seasonal snowmelt input. However, the tritium values associated with MVN-3 and MVN-4 suggest at least some mixing, with values of 13.4 TU and 12.5 TU, respectively. Surface water samples from Chalk Creek show average tritium values of 11.1 TU, and 18O values of -14.87 per mil. Groundwater samples were captured using monitoring wells, and plotted according to the depth of screening. Alluvial wells carried a seasonal signal similar

  19. New Stable Isotopic Techniques of Nitrate Applied to Investigation of Estuarine Nitrate Sources in Elkhorn Slough, CA

    NASA Astrophysics Data System (ADS)

    Wankel, S. D.; Paytan, A.; Kendall, C.

    2003-12-01

    Elkhorn Slough is a tidally flushed estuary with exceptionally high amounts of N loading within the watershed. The main sources of N are thought to be in the form of nitrate from surface water runoff, agricultural fields, dairy farms, and urban runoff. More poorly quantified sources of nitrate may also include significant groundwater discharge as well as tidal inputs from Monterey Bay. Traditional studies, involving natural abundance stable isotopes within the N cycle, have been limited to δ 15N and thus to a 'one-dimensional' perspective on N cycling. The use of a multiple isotope (δ 15N and δ 18O) model allows disentanglement of superimposed transformation processes. Furthermore, a dual isotope approach permits a more discrete characterization of these sources, with the goal of estimating their roles in the N budget of Elkhorn Slough. The isotopic values of nitrate from transects, conducted in the main channel of the slough during both flood and ebb tides, suggest mixing of a marine end member (δ 15N = +11.6%; δ 18O = +10%) with several other nitrate sources having discernable isotopic compositions. The Moss Landing Harbor, near the mouth of Elkhorn Slough, has very high nitrate concentrations (>200uM) and is likely a significant source of nitrate to the slough (δ 15N = +15.4%; δ 18O = +9.9%). With each rising tide, there is a distinct tidal bore from Monterey Bay also delivering nitrate (approx. 30uM) of a unique nitrate isotopic composition (δ 15N = +5.3%; δ 18O = +9.9%). During certain sample collections, nitrate from the head of the slough, with an isotopic composition of +5.2% (δ 15N ) and +22.0% (δ 18O), is suggestive of nitrification (δ 15N = +5.2%; δ 18O = +22.3%). Each of these estuarine members reflects both the composition of the original source of nitrate within the sub-watershed as well as the degree of transformation of these sources. The δ 18O value for marine nitrate in this system is markedly higher than has been reported in open

  20. Pooled versus separate measurements of tree-ring stable isotopes.

    PubMed

    Dorado Liñán, Isabel; Gutiérrez, Emilia; Helle, Gerhard; Heinrich, Ingo; Andreu-Hayles, Laia; Planells, Octavi; Leuenberger, Markus; Bürger, Carmen; Schleser, Gerhard

    2011-05-01

    δ(13)C and δ(18)O of tree rings contain time integrated information about the environmental conditions weighted by seasonal growth dynamics and are well established as sources of palaeoclimatic and ecophysiological data. Annually resolved isotope chronologies are frequently produced by pooling dated growth rings from several trees prior to the isotopic analyses. This procedure has the advantage of saving time and resources, but precludes from defining the isotopic error or statistical uncertainty related to the inter-tree variability. Up to now only a few studies have compared isotope series from pooled tree rings with isotopic measurements from individual trees. We tested whether or not the δ(13)C and the δ(18)O chronologies derived from pooled and from individual tree rings display significant differences at two locations from the Iberian Peninsula to assess advantages and constraints of both methodologies. The comparisons along the period 1900-2003 reveal a good agreement between pooled chronologies and the two mean master series which were created by averaging raw individual values (Mean) or by generating a mass calibrated mean (MassC). In most of the cases, pooled chronologies show high synchronicity with averaged individual samples at interannual scale but some differences also show up especially when comparing δ(18)O decadal to multi-decadal variations. Moreover, differences in the first order autocorrelation among individuals may be obscured by pooling strategies. The lack of replication of pooled chronologies prevents detection of a bias due to a higher mass contribution of one sample but uncertainties associated with the analytical process itself, as sample inhomogeneity, seems to account for the observed differences.

  1. 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

  2. The separation of stable isotopes of carbon

    NASA Astrophysics Data System (ADS)

    Oziashvili, E. D.; Egiazarov, A. S.

    1989-04-01

    The present state of work on the separation of carbon isotopes by diffusion, fractional distillation, chemical isotopic exchange, and the selective excitation and dissociation of molecules in electrical discharges or in the field of laser radiation has been examined. The characteristics of new laboratory and industrial assemblies for separating carbon isotopes have been described. Promising directions of study aimed at developing effective technological processes for separating carbon isotopes have been noted. The bibliography contains 148 references.

  3. 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

  4. Stable isotope ratios as a tool in microbial forensics--part 3. Effect of culturing on agar-containing growth media.

    PubMed

    Kreuzer-Martin, Helen W; Chesson, Lesley A; Lott, Michael J; Ehleringer, James R

    2005-11-01

    Stable isotope ratios of hydrogen and oxygen in microbes have been shown to be functions of the corresponding isotope ratios of the water with which the culture medium was prepared, and thus to contain a potential geographic signal. Water can evaporate from agar (solid) media during culturing, changing its isotope ratios. Here we describe the effect of drying on the isotope ratios of water extracted from agar media and the H and O stable isotope ratios ratios of Bacillus subtilis spores cultured on agar. The delta2H vs delta18O relationship of water in Petri dish agar was surprisingly constant during evaporation regardless of the ambient relative humidity, making it possible to calculate the approximate isotope ratios of the original water, even in significantly evaporated agar. The H stable isotope ratios of spores cultured on agar remained relatively unchanged as the agar dried, but the O ratio became significantly enriched.

  5. Competition for water between walnut seedlings (Juglans regia) and rye grass (Lolium perenne) assessed by carbon isotope discrimination and delta18O enrichment.

    PubMed

    Picon-Cochard, C; Nsourou-Obame, A; Collet, C; Guehl, J M; Ferhi, A

    2001-02-01

    Container-grown walnut seedlings (Juglans regia L.) were subjected to competition with rye grass (Lolium perenne L.) and to a 2-week soil drying cycle. One and 2 weeks after the beginning of the drought treatment, H2 18O (delta approximately equals +100%) was added to the bottom layer of soil in the plant containers to create a vertical H2 18O gradient. Rye grass competition reduced aboveground and belowground biomass of the walnut seedlings by 60%, whereas drought had no effect. The presence of rye grass reduced the dry weight of walnut roots in the upper soil layer and caused a 50% reduction in lateral root length. Rye grass competition combined with the drought treatment reduced walnut leaf CO2 assimilation rate (A) and leaf conductance (gw) by 20 and 39%, respectively. Transpiration rates in rye grass, both at the leaf level and at the plant or tiller level, were higher than in walnut seedlings. Leaf intrinsic water-use efficiency (A/gw) of walnut seedlings increased in response to drought and no differences were observed between the single-species and mixed-species treatments, as confirmed by leaf carbon isotope discrimination measurements. Measurement of delta18O in soil and in plant xylem sap indicated that the presence of rye grass did not affect the vertical profile of soil water uptake by walnut seedlings. Walnut seedlings and rye grass withdrew water from the top and middle soil layers in well-watered conditions, whereas during the drought treatment, walnut seedlings obtained water from all soil layers, but rye grass took up water from the bottom soil layer only.

  6. 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.

  7. 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.

  8. Stable carbon and oxygen isotopic analysis of atmospheric carbon monoxide using continuous-flow isotope ratio MS by isotope ratio monitoring of CO.

    PubMed

    Tsunogai, Urumu; Nakagawa, Fumiko; Komatsu, Daisuke D; Gamo, Toshitaka

    2002-11-15

    We have developed a rapid and simple measurement system for both content and stable isotopic compositions (13C and 18O) of atmospheric CO, using continuous-flow isotope ratio mass spectrometry by simultaneously monitoring the CO+ ion currents at masses 28, 29, and 30. The analytical system consisted sequentially of a sample trapping port (liquid nitrogen temperature silica gel and molecular sieve 5A), a gas dryer, a CO purification column (molecular sieve 5A), a cryofocusing unit, and a final purification column using a GC capillary. Analytical precision of 0.2 per thousand for 13C and 0.4 per thousand for 18O can be realized for samples that contain as little as 300 pmol of CO within 40 min for one sample analysis. Analytical blanks associated with the method are less than 1 pmol. The extent of analytical error in delta13C due to mass-independent fractionation of oxygen in natural CO is estimated to be less than 0.3 per thousand. Based on this system, we report herein a kinetic isotopic effect during CO consumption in soil.

  9. Long-term monitoring of stable isotopic compositions of precipitation over volcanic island, Jeju, Korea

    NASA Astrophysics Data System (ADS)

    Kim, Young-Hee; Koh, Dong-Chan; Park, Won-Bae; Bong, Yeon-Sik; Lee, Kwang-Sik; Lee, Jeonghoon

    2015-04-01

    Stable isotopic compositions of precipitation can be widely used to understand moisture transport in the atmosphere, proxies for paleoclimate and interactions between groundwater and precipitation. Over Jeju volcanic island, located southwest of the Korean Peninsula, precipitation penetrated directly into the highly permeable aquifer is the main source of groundwater. In this study, long-term stable isotopic compositions of precipitation over Jeju Island are characterized to describe spatial and temporal patterns for hydrology and paleoclimate. At fifteen sites from September 2000 to December 2003, precipitation samples were collected and analyzed by Isotope Ratio Mass Spectrometer at the Korea Basic Science Institute. Compared to Lee et al. (2003), the two seasonal local meteoric water lines widen, which may change the relative contributions of winter and summer season precipitation to the groundwater recharge. The precipitation isotopes are inversely correlated with precipitation amount in summer, whereas they do not show a strong correlation with surface air temperature. The precipitation isotopes monthly averaged relatively show a periodic function (R2=0.63 and 0.40 for hydrogen and oxygen, respectively), and deuterium excess (d-excess=δD-8×δ18O) shows a strong pattern of quadratic function (R2=0.97), which is related to a seasonal change of air masses. Altitude effect of precipitation isotopes, which can be a clue to reveal sources of groundwater, can be observed in every aspect of the volcanic island (for the oxygen isotope, -0.14‰ for east and west, -0.18‰ for north and -0.085‰ for south per 100 m). Our analysis of precipitation isotopes will be helpful to provide limitations and opportunities for paleoclimate reconstruction using isotopic proxies and water movement from atmosphere to subsurface.

  10. 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.

  11. Geology, Petrology and O and H isotope geochemistry of remarkably 18O depleted Paleoproterozoic rocks of the Belomorian Belt, Karelia, Russia, attributed to global glaciation 2.4 Ga

    NASA Astrophysics Data System (ADS)

    Bindeman, I. N.; Serebryakov, N. S.

    2011-06-01

    This paper deals with strongly 18O-depleted (down to - 27.3‰ VSMOW) 1.9Ga Paleoproterozoic mid-grade metamorphic rocks found in the Belomorian Belt of Karelia (E. Baltic Shield). The protolith of these rocks is attributed to have been altered by glacial meltwaters during the world's first 2.4-2.3 Ga Paleoproterozoic "Slushball" glaciation, when Karelia was located near equatorial latitudes. We describe in detail three and report seven new localities with unusually depleted 18O signatures that now span 220 km across the Belomorian Belt. Hydrogen isotope ratios measured in amphibole, biotite and staurolite also display remarkably low values of - 212 to - 235‰. Isotope mapping in the three best exposed localities has allowed us to identify the world's most 18O depleted rock, located at Khitostrov with a δ 18O value - 27‰. In Khitostrov samples, zircons have normal δ 18O detrital cores and low-δ 18O metamorphic rims. Mapping demonstrates that zones of δ 18O depletion occur in a concentric pattern 100-400 m in dimension, and each locality displays significant δ 18O and δD heterogeneity on a meter to centimeter scale, characteristic of meteoric-hydrothermal systems worldwide. The zone of maximum δ 18O depletions usually has the highest concentration of metamorphic corundum, rutile, and zircon and also display doubled concentrations of insoluble trace elements (Zr, Ti, Cr, HREE). These results are explained by elemental enrichment upon mass loss during hydrothermal dissolution in pH-neutral meteoric fluid. Remarkably low-δ 18O and δD values suggest that alteration could have only happened by glacial meltwaters in a subglacial rift zone. Many localities with δ 18O depletions occur inside metamorphozed 2.4 Ga gabbro-noritic intrusions, or near their contact with Belomorian gneisses, implying that the intrusions were driving meteoric hydrothermal systems during the known 2.4 Ga episode of Belomorian rifting. Given that the isotopically-depleted localities now

  12. Relationships between water and paddlefish Polyodon spathula dentary elemental and stable-isotopic signatures: potential application for reconstructing environmental history.

    PubMed

    Bock, L R; Whitledge, G W; Pracheil, B; Bailey, P

    2017-02-01

    The objectives of this study were to characterize relationships between water and paddlefish Polyodon spathula dentary Sr:Ca, δ(18) O and stable hydrogen isotope ratio (δD) to determine the accuracy with which individual P. spathula could be assigned to their collection locations using dentary-edge Sr:Ca, δD and δ(18) O. A laboratory experiment was also conducted to determine whether dentary Sr:Ca in age 0 year P. spathula would reflect shifts in water Sr:Ca to which fish were exposed. Significant linear relationships between water and dentary Sr:Ca, δD and δ(18) O were observed, although the relationship between water and dentary δ(18) O was weaker than those for Sr:Ca and δD. Classification success for individual fish to collection locations that differed in water Sr:Ca, δD and δ(18) O ranged from 86 to 100% based on dentary-edge Sr:Ca, δD and δ(18) O. Dentary Sr:Ca increased significantly in laboratory-reared age 0 year P. spathula following 4 weeks of exposure to elevated water Sr:Ca; dentary Sr:Ca of fish held in water with elevated Sr:Ca was also significantly higher than that of control fish reared in ambient laboratory water. Results indicated that P. spathula dentaries reflect water signatures for commonly-applied natural chemical markers and strongly suggest that dentary microchemistry and stable-isotopic compositions will be applicable for reconstructing P. spathula environmental history in locations where sufficient spatial differences in water chemistry occur.

  13. Paleocene to Early Eocene paleoceanography of the Middle East: The δ13C and δ18O isotopes from foraminiferal calcite

    NASA Astrophysics Data System (ADS)

    Charisi, Stella D.; Schmitz, Birger

    1998-02-01

    Paleocene to early Eocene benthic foraminiferal δ13C and δ18O records from southern Tethyan sections at Ben Gurion, Israel (paleodepth 500-700 m), and Gebel Aweina, Egypt (paleodepth 150-200 m), show generally similar trends but 1-3‰ more negative values than coeval deep-sea isotopic records. In both Tethyan sections a negative δ13C excursion of 2.5-3‰ marks the benthic extinction event in the latest Paleocene. For at least 1 m.y. after this event, δ13C values were 1.5-2‰ more negative on the shelf than at upper bathyal depths, reflecting a deepening of the oxygen minimum zone, possibly related to an increase or spatial shift in upwelling. Benthic δ18O records indicate a 2-4°C temperature gradient between the shelf and upper bathyal depths. Temperature-salinity reconstructions suggest that upwelling was a dominant mechanism for surface water formation in this part of the southern Tethys during the late Paleocene.

  14. 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.

  15. 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.

  16. 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

  17. Natural and Anthropogenic Impacts on the Stable Isotopes of Nitrogen and Oxygen of Ice-Core Nitrate

    NASA Astrophysics Data System (ADS)

    Walters, W.; Michalski, G. M.

    2013-12-01

    The stable isotopes of nitrogen and oxygen of the Ross Ice Drainage System (RIDS) ice-core nitrate were measured in approximately 2-3 year time resolution using a Delta V Isotope Ratio Mass Spectrometer (IRMS). The nitrogen isotope variation (δ15N) and the mass-independent fractionation of oxygen (Δ17O = δ17O - 0.52*δ18O) yield a detailed picture of the changes in the global nitrogen cycling and the shift in the oxidation capacity of the atmosphere in response to natural and anthropogenic induced climate change. This is one of the few studies on stable isotopes of ice-core nitrate for time periods prior to the 1800's and will increase our understanding of the oxidation feedbacks of the atmosphere in response to volcanic events, the Little Ice Age, the Maunder Minimum, and anthropogenic emissions in the Southern Hemisphere.

  18. 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

  19. Stable isotope views on ecosystem function: challenging or challenged?

    PubMed

    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

    2010-06-23

    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, Ubeda, 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.

  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. Using stable isotopes to determine seabird trophic relationships

    USGS Publications Warehouse

    Hobson, Keith A.; Piatt, John F.; Pitocchelli, Jay

    1994-01-01

    1. The stable isotopes of nitrogen (δ15N) and carbon (δ13C) were analysed in 22 species of marine birds from coastal waters of the northeast Pacific Ocean. Analyses confirm that stable nitrogen isotopes can predict seabird trophic positions.2. Based on δ15N analyses, seabird trophic-level inferences generally agree with those of conventional dietary studies, but suggest that lower trophic-level organisms are more important to several seabirds than was recognized previously.3. Stable-carbon isotope analysis may be a good indicator of inshore vs. offshore feeding preference.4. In general, stable-isotope analysis to determine trophic level offers many advantages over conventional dietary approaches since trophic inferences are based on time-integrated estimates of assimilated and not just ingested foods, and isotopic abundance represents a continuous variable that is amenable to statistical analysis.

  2. 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

  3. 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

  4. 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

  5. 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.

  6. 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.

  7. 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

  8. 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

  9. 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.

  10. 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.

  11. 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

  12. Variability of surface ocean radiocarbon and stable isotopes in the southwestern Pacific

    NASA Astrophysics Data System (ADS)

    Druffel, Ellen R. M.; Griffin, Sheila

    1999-10-01

    We present high-precision radiocarbon (Δ14C) results and stable isotope18O and δ13C) records for a coral from Heron Island (23°S, 152°E) and new stable isotope18O and δ13C) records for annual coral bands from Abraham Reef (22°S, 153°E) in the southern Great Barrier Reef studied earlier [Druffel and Griffin, 1993]. These tracers provide unique information on the regional water mass history, and together these data allow us to constrain the variability of circulation in the upper Pacific over the past four centuries. First, we observe decreases in δ18O of coral from Abraham Reef and Heron Island, indicating an increase in sea surface temperature and/or a decrease in surface salinity since 1850. Second, the small Suess effect value (Δ14C decrease from 1880 to 1955, due mostly to fossil fuel CO2) observed previously at Abraham Reef[Druffel and Griffin, 1993] is confirmed in the measurements reported here from the Heron Island coral. This value is low compared to those observed in other areas of the ocean [Druffel, 1997; Druffel and Linick, 1978; Nozaki et al., 1978] between 1880 and 1955. Third, we report alterations in the correlation between El Niño events and the occurrence of low Δ14C, which is indicative of long-term change(s) in circulation in the SW Pacific. The Δ14C shifts reported here are not large, but even small temporal changes in prebomb Δ14C suggest that important changes in the large-scale state of the ocean have occurred, such as a temporal change in circulation.

  13. 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.

  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. Metal stable isotope signatures as tracers in environmental geochemistry.

    PubMed

    Wiederhold, Jan G

    2015-03-03

    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.

  16. 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).

  17. 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

  18. 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.

  19. 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.

  20. First ice core records of NO3- stable isotopes from Lomonosovfonna, Svalbard

    NASA Astrophysics Data System (ADS)

    Vega, C. P.; Pohjola, V. A.; Samyn, D.; Pettersson, R.; Isaksson, E.; Björkman, M. P.; Martma, T.; Marca, A.; Kaiser, J.

    2015-01-01

    from two ice cores drilled at Lomonosovfonna, Svalbard, covering the period 1957-2009, and 1650-1995, respectively, were analyzed for NO3-concentrations, and NO3- stable isotopes (δ15N and δ18O). Post-1950 δ15N has an average of (-6.9 ± 1.9)‰, which is lower than the isotopic signal known for Summit, Greenland but agrees with values observed in recent Svalbard snow and aerosol. Pre-1900 δ15N has an average of (4.2 ± 1.6)‰ suggesting that natural sources, enriched in the 15 N isotope, dominated before industrialization. The post-1950 δ18O average of (75.1 ± 4.1)‰ agrees with data from low and polar latitudes, suggesting similar atmospheric NOy (NOy = NO + NO2 + HNO3) processing pathways. The combination of anthropogenic source δ15N and transport isotope effect was estimated as -29.1‰ for the last 60 years. This value is below the usual range of NOx (NOx = NO + NO2) anthropogenic sources which is likely the result of a transport isotope effect of -32‰. We suggest that the δ15N recorded at Lomonosovfonna is influenced mainly by fossil fuel combustion, soil emissions, and forest fires; the first and second being responsible for the marked decrease in δ15N observed in the post-1950s record with soil emissions being associated to the decreasing trend in δ15N observed up to present time, and the third being responsible for the sharp increase of δ15N around 2000.

  1. Isotope effects in the CO dimer: Millimeter wave spectrum and rovibrational calculations of (12C18O)2

    NASA Astrophysics Data System (ADS)

    Surin, L. A.; Fourzikov, D. N.; Giesen, T. F.; Schlemmer, S.; Winnewisser, G.; Panfilov, V. A.; Dumesh, B. S.; Vissers, G. W. M.; van der Avoird, A.

    2006-09-01

    The millimeter wave spectrum of the isotopically substituted CO dimer, (C12O18)2, was studied with the Orotron jet spectrometer, confirming and extending a previous infrared study [A. R. W. McKellar, J. Mol. Spectrosc. 226, 190 (2004)]. A very dilute gas mixture of CO in Ne was used, which resulted in small consumption of C12O18 sample gas and produced cold and simple spectra. Using the technique of combination differences together with the data from the infrared work, six transitions in the 84-127GHz region have been assigned. They belong to two branches, which connect four low levels of A+ symmetry to three previously unknown levels of A- symmetry. The discovery of the lowest state of A- symmetry, which corresponds to the projection K =0 of the total angular momentum J onto the intermolecular axis, identifies the geared bending mode of the C12O18 dimer at 3.607cm-1. Accompanying rovibrational calculations using a recently developed hybrid potential from ab initio coupled cluster [CCSD(T)] and symmetry-adapted perturbation theory calculations [G. W. M. Vissers et al., J. Chem. Phys. 122, 054306 (2005)] gave very good agreement with experiment. The isotopic dependence of the A+/A- energy splitting, the intermolecular separation R, and the energy difference of two ground state isomers, which change significantly when O18 or C13 are substituted into the normal (C12O16)2 isotopolog [L. A. Surin et al., J. Mol. Spectrosc. 223, 132 (2004)], was explained by these calculations. It turns out that the change in anisotropy of the intermolecular potential with respect to the shifted monomer centers of mass is particularly significant.

  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 fractionation in speleothems as a proxy for subsurface environmental changes, Milchbach cave (Switzerland)

    NASA Astrophysics Data System (ADS)

    Luetscher, M.; Hoffmann, D. L.; Smart, P. L.; Spötl, C.

    2009-04-01

    Recent modelling work concluded that stable isotope fractionation along speleothem growth layers is largely controlled by cave temperature and drip interval (e.g., Mühlinghaus et al. 2007, Romanov et al. 2008). The magnitude of isotope fractionation could, therefore, be used as a proxy of the subsurface depositional environment. Here, we present evidence of changing isotopic fractionation in speleothems from a periglacial karst system, which experienced drastic changes in cave ventilation and hydrology during the Holocene. Three coeval stalagmites were sampled from Milchbach cave (Switzerland) and U/Th-dated to between 2 and 8.6 ka. 2D mapping of stable isotopes reveals major changes in δ13C and δ18O along individual growth layers. These changes correlate noticeably with changes in the calcite fabric and speleothem growth rate suggesting that changes in drip rate were the predominant control, possibly related to fluctuations of the mass balance of the Upper Grindelwald Glacier. References: Mühlinghaus C., Scholz D., Mangini A., 2007. Modelling stalagmite growth and δ13C as a function of drip interval and temperature. Geochimica et Cosmochimica Acta, 71(11), 2780-2790. Romanov, D., Kaufmann, G., Dreybrodt, W., 2008. δ13C profiles along growth layers of stalagmites: Comparing theoretical and experimental results. Geochimica et Cosmochimica Acta, 72(2), 438-448.

  4. Beam delivery for stable isotope separation

    NASA Astrophysics Data System (ADS)

    Forbes, Andrew; Strydom, Hendrick J.; Botha, Lourens R.; Ronander, Einar

    2002-10-01

    In the multi-photon dissociation process of Carbon isotope enrichment, IR photons are used to selectively excite a molecule with the given isotopic base element. This enrichment process is very sensitive to the beam's intensity and wavelength. Because the intensity is determined by the propagation of the field, the enrichment factors are also very dependent on the field propagation. In this paper, the influence of the wavelength and intensity of the beam, on the isotope selective dissociation of a CFC compound is investigated both experimentally and theoretically. Consideration is also given to some of the factors that influence the delivery of various beams to the reactor chamber, and their subsequent propagation through the reactor. The results show that suitable beam forming can lead to an improved isotope separation process.

  5. Stable carbon isotope analysis of coprocessing materials

    SciTech Connect

    Lancet, M.S.; Winschel, R.A.; Burke, F.P.

    1991-03-01

    Research on coprocessing materials/products continued. Major topics reported here are described below. Microautoclave runs are described in which gases and insoluble organic matter produced from five coals and gases produced from three petroleum resids were analyzed to study feedstock/product selective isotopic fractionation. Selective isotopic fractionation was further explored through isotope analysis of the feed New Mexico coal and products from a continuous coal liquefaction run (HRI CC-10 or 227-68). Feeds (Texas lignite/Maya VSB) and products from two HRI continuous coprocessing runs (227-54 and 238-12) were analyzed. The results were corrected for selective isotopic fractionation and carbon sourcing was performed for the product fractions. {sup 1}H-NMR and phenolic -OH determinations are reported for all continuous unit samples obtained under this contract. 13 refs., 17 figs., 40 tabs.

  6. 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,...

  7. Stable Isotope Systematics of Martian Perchlorate

    NASA Astrophysics Data System (ADS)

    Martin, P.; Farley, K. A.; Archer, D., Jr.; Atreya, S. K.; Conrad, P. G.; Eigenbrode, J. L.; Fairen, A.; Franz, H. B.; Freissinet, C.; Glavin, D. P.; Mahaffy, P. R.; Malespin, C.; Ming, D. W.; Navarro-Gonzalez, R.; Sutter, B.

    2015-12-01

    Chlorine isotopic compositions in HCl released during evolved gas analysis (EGA) runs have been detected by the Sample Analysis at Mars (SAM) instrument on the Curiosity rover ranging from approximately -9‰ to -50‰ δ37Cl, with two spatially and isotopically separated groups of samples averaging -15‰ and -45‰. These extremely low values are the first such detection of any known natural material; common terrestrial values very rarely exceed ±5‰, and the most extreme isotopic signature yet detected elsewhere in the solar system are values of around +24‰ on the Moon. The only other known location in the solar system with large negative chlorine isotopes is the Atacama Desert, where perchlorate with -14‰ δ37Cl has been detected. The Atacama perchlorate has unusual Δ17O signatures associated with it, indicating a formation mechanism involving O3, which suggests an atmospheric origin of the perchlorate and associated large isotopic anomalies. Identification of non-zero positive Δ17O signatures in the O2 released during EGA runs would allow definitive evidence for a similar process having occurred on Mars. Perchlorate is thought to be the most likely source of HCl in EGA runs due to the simultaneous onset of O2 release. If perchlorate is indeed the HCl source, atmospheric chemistry could be responsible for the observed isotopic anomalies, with variable extents of perchlorate production producing the isotopic variability. However, chloride salts have also been observed to release HCl upon heating; if the timing of O2 release is merely coincidental, observed HCl could be coming from chlorides. At thermodynamic equilibrium, the fractionation factor of perchlorate reduction is 0.93, meaning that differing amounts of post-deposition reduction of isotopically normal perchlorate to chloride could account for the highly variable Cl isotopes. Additionally, post-deposition reduction could account for the difference between the two Cl isotopic groups if perchlorate

  8. Biogeochemistry of the stable hydrogen isotopes

    NASA Astrophysics Data System (ADS)

    Estep, Marilyn F.; Hoering, Thomas C.

    1980-08-01

    The fractionation of H isotopes between the water in the growth medium and the organically bonded H from microalgae cultured under conditions, where light intensity and wavelength, temperature, nutrient availability, and the H isotope ratio of the water were controlled, is reproducible and light dependant. All studies were based either on the H isotope ratios of the total organic H or on the lipids, where most of the H is firmly bonded to C. H bonded into other macromolecules, proteins, carbohydrates and nucleic acids, does not exchange with water, when algae are incubated in water enriched with deuterium. Only after the destruction of quaternary H bonds are labile hydrogens in macromolecules free to exchange with water. By growing algae (18 strains), including blue-green algae, green algae and diatoms, in continuous light, the isotope fractionations in photosynthesis were reproducibly -93 to -178 %. depending on the organism tested. This fractionation was not temperature dependent. Microalgae grown in total darkness with an organic substrate did not show the isotope fractionation seen in cells grown in light. In both light- and dark-grown algae, however, additional depletion of deuterium (-30 to -60%.) in cellular organic matter occurs during the metabolism of carbohydrates to form lipids. Plants from several natural populations also fractionated isotopes during photosynthesis by an average of -90 to -110%. In addition, the organically bonded H in nonsaponifiable lipids was further fractionated by -80%. from that in saponifiable lipids, isolated from two geographically distinct populations of marsh plants. This difference between H isotope ratios of these two groups of lipids provides an endogenous isotopic marker.

  9. 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.

  10. Stable isotopes of carbon dioxide in soil gas over massive sulfide mineralization at Crandon, Wisconsin

    USGS Publications Warehouse

    Alpers, C.N.; Dettman, D.L.; Lohmann, K.C.; Brabec, D.

    1990-01-01

    Stable isotope ratios of oxygen and carbon were determined for CO2 in soil gas in the vicinity of the massive sulfide deposit at Crandon, Wisconsin with the objective of determining the source of anomalously high CO2 concentrations detected previously by McCarthy et al. (1986). Values of ??13C in soil gas CO2 from depths between 0.5 and 1.0 m were found to range from -12.68??? to -20.03??? (PDB). Organic carbon from the uppermost meter of soil has ??13C between -24.1 and -25.8??? (PDB), indicating derivation from plant species with the C3 (Calvin) type of photosynthetic pathway. Microbial decomposition of the organic carbon and root respiration from C3 and C4 (Hatch-Slack) plants, together with atmospheric CO2 are the likely sources of carbon in soil gas CO2. Values of ??18O in soil-gas CO2 range from 32 to 38??? (SMOW). These ??18O values are intermediate between that calculated for CO2 gas in isotopic equilibrium with local groundwaters and that for atmospheric CO2. The ??18O data indicate that atmospheric CO2 has been incorporated by mixing or diffusion. Any CO2 generated by microbial oxidation of organic matter has equilibrated its oxygen isotopes with the local groundwaters. The isotopic composition of soil-gas CO2 taken from directly above the massive sulfide deposit was not distinguishable from that of background samples taken 1 to 2 km away. No enrichment of the ??13C value of soil-gas CO2 was observed, contrary to what would be expected if the anomalous CO2 were derived from the dissolution of Proterozoic marine limestone country rock or of Paleozoic limestone clasts in glacial till. Therefore, it is inferred that root respiration and decay of C3 plant material were responsible for most CO2 generation both in the vicinity of the massive sulfide and in the "background" area, on the occasion of our sampling. Interpretation of our data is complicated by the effects of rainfall, which significantly reduced the magnitude of the CO2 anomaly. Therefore, we cannot

  11. 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

  12. Effect of pH decline on foraminiferal stable isotopes during the Paleocene-Eocene Thermal Maximum?

    NASA Astrophysics Data System (ADS)

    Uchikawa, J.; Zeebe, R. E.

    2009-12-01

    Pioneering culture experiments by Spero et al. (1997) demonstrated that seawater pH (or carbonate chemistry) has a marked effect on planktonic foraminiferal stable oxygen and carbon isotopes18O and δ13C). Both δ18O and δ13C become isotopically heavier as seawater pH decreases (the “pH effect”). Several studies now argue that δ18O and δ13C of benthic foraminifera are similarly influenced by the pH effect. As a result, paleooceanographic information based on foraminiferal δ18O and δ13C can be significantly biased for the time-window during which seawater pH was notably different from the modern condition or varied rapidly. A prime example of such is the Paleocene-Eocene Thermal Maximum (PETM). Widespread dissolution of sedimentary CaCO3 in the PETM strata (e.g., Zachos et al., 2005) suggests significant ocean acidification during this time interval. In this study, we examine the magnitude of the pH effect on foraminiferal δ18O and δ13C during the PETM. First we will estimate the relative pH decline from the pre-PETM steady state in the surface and deep ocean reservoirs in response to 2,000 ~ 5,000 Pg of carbon input using a carbon cycle model (Zeebe et al., 2009). We will then apply the empirical relationships obtained from the culture experiments by Spero et al. (1997) to calculate the ranges of errors in the foraminiferal δ18O and δ13C that could arise due to the pH effect during the PETM. {REFERENCES} Spero et al. (1997) Nature, v390, p497-500: Zachos et al. (2005) Science, v308, p1611-1615: Zeebe et al. (2009) Nature Geoscience, v2, p576-580.

  13. 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

  14. 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.

  15. 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.

  16. 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.

  17. 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...

  18. 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...

  19. 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...

  20. 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...

  1. 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.

  2. 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.

  3. 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

  4. Evaluation of bioremediation systems utilizing stable carbon isotope analysis

    SciTech Connect

    Van de Velde, K.; Nowell, C.; Marley, M.C.

    1994-12-31

    Carbon, whether in an organic or inorganic form, is composed primarily of two stable isotopes, carbon-12 and carbon-13. The ratio of carbon-12 to carbon-13 is approximately 99:1. The stable carbon isotope ratios of most natural carbon materials of biological interest range from approximately 0 to {minus}110 per mil ({per_thousand}) versus the PDB standard. Utilizing stable carbon isotope analysis, it is often possible to determine the source(s) of the liberated carbon dioxide, thereby confirming successful mineralization of the targeted carbon compound(s) and, if the carbon dioxide results from multiple carbon compounds, in what ratio the carbon compounds are mineralized. Basic stable isotope `theory` recommended sampling procedures and analysis protocols are reviewed. A case study involving fuel oil presented on the application of stable carbon isotope analysis for the monitoring and evaluation of in situ bioremediation. At the site, where a field bioventing study was being conducted, multiple potential sources of carbon dioxide production existed. Additional potential applications of stable carbon isotope analysis for bioremediation evaluation and monitoring are discussed.

  5. Spatial distribution and controlling factors of stable isotopes in meteoric waters on the Tibetan Plateau: Implications for paleoelevation reconstruction

    NASA Astrophysics Data System (ADS)

    Li, Lin; Garzione, Carmala N.

    2017-02-01

    Debates persist about the interpretations of stable isotope based proxies for the surface uplift of the central-northern Tibetan Plateau. These disputes arise from the uncertain relationship between elevation and the δ18 O values of meteoric waters, based on modern patterns of isotopes in precipitation and surface waters. We present a large river water data set (1,340 samples) covering most parts of the Tibetan Plateau to characterize the spatial variability and controlling factors of their isotopic compositions. Compared with the amount-weighted mean annual oxygen isotopic values of precipitation, we conclude that river water is a good substitute for isotopic studies of precipitation in the high flat (e.g., elevation >3,300 m) interior of the Tibetan Plateau in the mean annual timescale. We construct, for the first time based on field data, contour maps of isotopic variations of meteoric waters (δ18 O, δD and d-excess) on the Tibetan Plateau. In the marginal mountainous regions of the Plateau, especially the southern through eastern margins, the δ18 O and δD values of river waters decrease with increasing mean catchment elevation, which can be modeled as a Rayleigh distillation process. However, in the interior of the Plateau, northward increasing trends in δ18 O and δD values are pronounced and present robust linear relations; d-excess values are lower than the marginal regions and exhibit distinct contrasts between the eastern (8 ‰- 12 ‰) and western (<8‰) Plateau. We suggest that these isotopic features of river waters in the interior of the Tibetan Plateau result from the combined effects of: 1) mixing of different moisture sources transported by the South Asian monsoon and Westerly winds; 2) contribution of moisture from recycled surface water; and 3) sub-cloud evaporation. We further provide a sub-cloud evaporation modified Rayleigh distillation and mixing model to simulate the isotopic variations in the western Plateau. Results of this work

  6. 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.

  7. Stable Chlorine Isotope Study: Application to Early Solar System Materials

    NASA Technical Reports Server (NTRS)

    Mala,ira. M/; Nyquist, L. E.; Reese, Y.; Shih, C-Y; Fujitani, T.; Okano, O.

    2010-01-01

    A significantly large mass fractionation between two stable chlorine isotopes is expected during planetary processes In addition, in view of the isotopic heterogeneity of other light elements, the chlorine isotopes can potentially be used as a tracer for the origins and evolutionary processes of early solar system materials. Due to analytical difficulties, however, current chlorine isotope studies on planetary materials are quite controversial among IRMS (gas source mass spectrometry) and/or TIMS (Thermal Ionization Mass Spectrometry) groups [i.e. 1-3]. Although a cross-calibration of IRMS and TIMS indicates that both techniques are sufficiently consistent with each other [4], some authors have claimed that the Cl-37/Cl-35 ratio of geological samples obtained by TIMS technique are, in general, misleadingly too high and variable compared to those of IRMS [3]. For example, almost no differences of Cl isotope composition were observed among mantle materials and carbonaceous meteorites by [3]. On the other hand, according to more recent IRMS work [2], significant Cl isotope variations are confirmed for mantle materials. Therefore, additional careful investigation of Cl isotope analyses are now required to confirm real chlorine isotope variations for planetary materials including carbonaceous chondrites [5]. A significantly large mass fractionation between two stable chlorine isotopes is expected during planetary processes In addition, in view of the isotopic heterogeneity of other light elements, the chlorine isotopes can potentially be used as a tracer for the origins and evolutionary processes of early solar system materials. Due to analytical difficulties, however, current chlorine isotope studies on planetary materials are quite controversial among IRMS (gas source mass spectrometry) and/or TIMS (Thermal Ionization Mass Spectrometry) groups [i.e. 1-3]. Although a cross-calibration of IRMS and TIMS indicates that both techniques are sufficiently consistent with each

  8. Effect of temperature on the oxygen isotope composition of carbon dioxide (δ18O) prepared from carbonate minerals by reaction with polyphosphoric acid: An example of the rhombohedral CaCO 3-MgCO 3 group minerals

    NASA Astrophysics Data System (ADS)

    Crowley, Stephen F.

    2010-11-01

    Measurement of the ratio of 18O to 16O in CO 2(δ18O) produced from rhombohedral carbonate minerals in the compositional range CaCO 3-MgCO 3 by reaction with polyphosphoric acid (PPA), at temperatures of between 25 and 110 °C, shows that values of δ18O are linearly correlated ( r o > 0.99) with the reciprocal of absolute reaction temperature (K/ T). This observation is consistent with earlier studies documenting the effect of temperature on the kinetic fractionation of oxygen isotopes between parent carbonate and product CO 2 and H 2O during acid decomposition. However, analysis of the resultant data reveals: (1) a progressive increase in dδ18O/dT-1 with increasing Mg content, and (2) a significant variation in dδ18O/dT-1 between individual samples of carbonate of identical lattice symmetry and similar chemical composition. The overall increase in gradient with increasing Mg content is assumed to reflect cation radius dependent factors that control the bonding environment at the interface between the metal cation exposed at the surface of the reacting carbonate solid and a H 2CO 3 transitional species during disproportionation of H 2CO 3 to CO 2 and H 2O ("cluster model" of Guo et al., 2009). Phase-specific variations in dδ18O/dT-1 might result from differences in lattice structure variables (e.g., degree of lattice distortion, extent of positional disorder, and non-ideal mixing of substituent cations where carbonates depart from end-member compositions). Lattice structure variables may be dependent on geochemical conditions pertaining at the time of carbonate precipitation (e.g., biosynthetic versus inorganic precipitates) and suggests that dδ18O/dT-1 has the potential to vary, within limits, in response to both the chemical composition and structure of each carbonate sample. Because the oxygen isotope composition of carbonate minerals (δ18O) measured on the VPDB scale is defined by the oxygen isotope composition of CO 2 prepared from NBS19 (calcite) by

  9. 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

  10. Stable isotope composition of human fingernails from Slovakia.

    PubMed

    Grolmusová, Zuzana; Rapčanová, Anna; Michalko, Juraj; Čech, Peter; Veis, Pavel

    2014-10-15

    Stable isotope composition of human fingernails has proven to be useful for documenting human dietary information and geographical patterns in archeological, forensic, anthropological and biological studies. Therefore, it is of interest to detect all factors influencing the stable isotopic composition in the certain regions in the world. Carbon and nitrogen isotope data of human fingernail keratin from 52 individuals from Slovakia were reported in this study. The online combustion and continuous flow isotope-ratio mass spectrometer Delta V Advantage was used for δ(13)C and δ(15)N analysis of fingernail keratin samples from 24 vegetarian and 28 omnivorous individuals. A group of people with frequent meat consumption showed enrichment in (13)C and (15)N isotopes in fingernails. A similar trend was observed with increasing seafood in an individual's diet. Moreover a significant difference was revealed between smokers and nonsmokers for both δ(13)C and δ(15)N values. These data were compared to previously published δ(13)C and δ(15)N fingernail values from across the globe. This study brings new information on the stable isotope signature of individuals from Slovakia and characterizes the Central European region for the first time. The stable isotope composition of fingernails is influenced by the frequency of meat and seafood consumption as well as smoking.

  11. Stable isotope ecology in the Omo-Turkana Basin.

    PubMed

    Cerling, Thure E; Levin, Naomi E; Passey, Benjamin H

    2011-01-01

    Stable isotopes provide an independent assessment of paleoenvironments in the Omo-Turkana Basin. Stable isotopes track the flow of oxygen and carbon through ecosystems and accordingly are not directly related to changes in mammalian faunal composition or sedimentology. Therefore, isotope studies give insight into the paleoenvironmental conditions in which human evolutionary trends have been recorded. The development of stable isotopes as indicators of continental environmental conditions has proceeded in parallel with questions about the conditions of human environment. What was the vegetation? How hot was it? How dry? What were the diets of animals living among early humans? And most persistently, how important were "savannas" to early hominids? In this review, we take the opportunity to provide extensive background on the use of isotopes in anthropological sites. The application of stable isotope ecology to anthropological sites in the Turkana Basin has a long history, but in many ways the Omo-Turkana Basin has been a proving ground for the development of new proxy methods for understanding tropical terrestrial environments in the Neogene and Quaternary. For that reason, we also describe some of the fundamental aspects of isotope ecology that developed outside the field of paleoanthropology.

  12. 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

  13. Stable isotope quality assurance using the 'calibrated IRMS' strategy.

    PubMed

    Meijer, Harro A J

    2009-06-01

    Procedures in our laboratory have always been directed towards complete understanding of all processes involved and corrections needed etc., instead of relying fully on laboratory reference materials. This rather principal strategy (or attitude) is probably not optimal in the economic sense, and is not necessarily more accurate either. Still, it has proven to be very rewarding in its capability to detect caveats that go undiscovered in the standard way of measurement, but that do influence the accuracy or reliability of the measurement procedure. An additional benefit of our laboratory procedures is that it makes us capable of assisting the International Atomic Energy Agency (IAEA) with primary questions like mutual scale assignments and comparison of isotope ratios of the same isotope in different matrices (like delta(18)O in water, carbonates and atmospheric CO(2)), establishment of the (17)O-(18)O relation, and the replenishment of the calibration standards. Finally, for manual preparation systems with a low sample throughput (and thus only few reference materials analysed) it may well be the only way to produce reliable results.

  14. Stable-Isotope and Chemical Time Series from Pamir (Fedchenko Glacier) firn core

    NASA Astrophysics Data System (ADS)

    Aizen, E. M.; Aizen, V. B.; Mayewski, P. A.; Joswiak, D. R.; Kaspari, S.; Finaev, A.; Surazakov, A.; Grigholm, B.

    2006-12-01

    During the summer of 2005, two firn cores were obtained at 5365 and 5206m on the Fedchenko glacier, the longest (77 km) and deepest (1 km) mid-latitude alpine glacier. The mean annual accumulation rate at 5206m was 1260mm, with extremely intensive increase of precipitation with altitude. The well-defined annual layering apparent in the stable isotope distribution reflects the continental climate. Two thirds of the annual precipitation during the cold season resulted in the most depleted mean isotope ratios, compared to other mean isotope ratios obtained from central Asian ice cores. The annual minimum isotope ratios decreased with altitudes as a result of the decreasing winter air temperatures and significant precipitation. The most enriched isotopes ratios at lower elevations point to an inverse altitudinal air temperature distribution during the summer, caused by intensive evaporation developing at lower elevations. The closest ä18O-äD ratios to the GMWL arethose related to the cold season, with maximum precipitation brought from the Atlantic. Seasonal deuterium excess and ä18O variations from the Pamir firn core both have maximum in the summer season and minimum in the winter, contrasting other central Asian cores. At the beginning of summer, warm south-Caspian cyclones brought precipitation with high d-excess values distinctive of re-cycled moisture that originated over internal sources. Concentrations of REE in the Pamir core are lower than concentrations found in the Tien Shan. Content of heavy metals in the Pamir firn core exceeds concentrations found in snow-firn of Antarctica, Greenland and even the more contaminated regions of the Alps and Altai. Concentration of antimony is comparable with the Alps and Canadian arctic. REE patterns suggest that loess is the dominant lithogenic material transported to the Pamir. Al, Fe, Nd and even Ca display the same variability as stable isotopes with depth, with maximum seasonal associated with isotope peaks

  15. Fractionation of metal stable isotopes by higher plants

    USGS Publications Warehouse

    Von Blanckenburg, F.; Von Wiren, N.; Guelke, M.; Weiss, D.J.; Bullen, T.D.

    2009-01-01

    Higher plants induce chemical reactions in the rhizosphere, facilitating metal uptake by roots. Fractionation of the isotopes in nutrients such as calcium, iron, magnesium, and zinc produces a stable isotope composition in the plants that generally differs from that of the growth medium. Isotope fractionation also occurs during transport of the metals within most plants, but its extent depends on plant species and on the metal, in particular, on the metal's redox state and what ligand it is bound to. The metal stable isotope variations observed in plants create an isotope signature of life at the Earth's surface, contributing substantially to our understanding of metal cycling processes in the environment and in individual organisms.

  16. Stable Isotope Ratios as Biomarkers of Diet for Health Research.

    PubMed

    O'Brien, Diane M

    2015-01-01

    Diet is a leading modifiable risk factor for chronic disease, but it remains difficult to measure accurately due to the error and bias inherent in self-reported methods of diet assessment. Consequently, there is a pressing need for more objective biomarkers of diet for use in health research. The stable isotope ratios of light elements are a promising set of candidate biomarkers because they vary naturally and reproducibly among foods, and those variations are captured in molecules and tissues with high fidelity. Recent studies have identified valid isotopic measures of short- and long-term sugar intake, meat intake, and fish intake in specific populations. These studies provide a strong foundation for validating stable isotopic biomarkers in the general US population. Approaches to improve specificity for specific foods are needed; for example, by modeling intake using multiple stable isotope ratios or by isolating and measuring specific molecules linked to foods of interest.

  17. Stable Isotope Ratios as Biomarkers of Diet for Health Research

    PubMed Central

    O’Brien, Diane M.

    2016-01-01

    Diet is a leading modifiable risk factor for chronic disease, but it remains difficult to measure accurately due to the error and bias inherent in self-reported methods of diet assessment. Consequently there is a pressing need for more objective biomarkers of diet for use in health research. The stable isotope ratios of light elements are a promising set of candidate biomarkers because they vary naturally and reproducibly among foods, and those variations are captured in molecules and tissues with high fidelity. Recent studies have identified valid isotopic measures of short and long-term sugar intake, meat intake, and fish intake in specific populations. These studies provide a strong foundation for validating stable isotopic biomarkers in the general United States population. Approaches to improve specificity for specific foods are needed, for example, by modeling intake using multiple stable isotope ratios, or by isolating and measuring specific molecules linked to foods of interest. PMID:26048703

  18. Stable carbon isotope analysis of coprocessing materials

    SciTech Connect

    Burke, F.P.; Winschel, R.A.; Lancet, M.S.

    1989-06-01

    The program is designed to address a substantial, demonstrated need of the coprocessing community (both exploratory and development) for a technique to quantitatively distinguish the contributions of the individual coprocessing feedstocks to the various products. The carbon isotope technique is currently in routine use for other applications. Results achieved this quarter include: Feed and product fractions from a Kentucky 9 coal/Kentucky tar sand bitumen coprocessing bench unit run at the Kentucky Center for Applied Energy Research (CAER) were analyzed for carbon isotope ratios. Corrections were made to the coal carbon recoveries and selectivities from the products of HRI Run 227-53. Feeds (Westerholt coal/Cold Lake VSB) and products from two periods of HRI coprocessing Run 238-1 were analyzed. Three petroleum samples and three coal samples were pyrolyzed at 800{degree}F for 30 min to determine the effect of pyrolysis on the isotopic homogeneity of each petroleum and coal sample. Products from each pyrolysis test were separated into five fractions; an additional set of coprocessing samples and a set of two-stage coal liquefaction samples were obtained from HRI for future work; work performed by the Pennsylvania State University show that microscopy is a promising method for distinguishing coal and petroleum products in residual coprocessing materials; and coal and petroleums that have large differences in carbon isotope ratios were identified for Auburn University. 7 refs., 2 figs., 12 tabs.

  19. 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

  20. Tooth enamel stable isotopes of Holocene and Pleistocene fossil fauna reveal glacial and interglacial paleoenvironments of hominins in Indonesia

    NASA Astrophysics Data System (ADS)

    Janssen, Renée; Joordens, Josephine C. A.; Koutamanis, Dafne S.; Puspaningrum, Mika R.; de Vos, John; van der Lubbe, Jeroen H. J. L.; Reijmer, John J. G.; Hampe, Oliver; Vonhof, Hubert B.

    2016-07-01

    The carbon (δ13C) and oxygen (δ18O) isotope compositions of fossilized animal tissues have become important proxies of paleodiet and paleoenvironment, but such stable isotope studies have not yet been extensively applied to the fossil assemblages of Sundaland (the biogeographical region comprising most of the Indonesian Archipelago). Here, we use the isotope composition of tooth enamel to investigate the diet and habitat of bovids, cervids, and suids from several Holocene and Pleistocene sites on Java and Sumatra. Our carbon isotope results indicate that individual sites are strongly dominated by either C3-browsers or C4-grazers. Herbivores from the Padang Highlands (Sumatra) and Hoekgrot (Java) cave faunas were mainly C3-browsers, while herbivores from Homo erectus-bearing sites Trinil and Sangiran (Java) utilized an almost exclusive C4 diet. The suids from all sites show a wide range of δ13C values, corroborating their omnivorous diet. For the dataset as a whole, oxygen and carbon isotope values are positively correlated. This suggests that isotopic enrichment of rainwater and vegetation δ18O values coincides with an increase of C4-grasslands. We interpret this pattern to mainly reflect the environmental contrast between glacial (drier, more C4) and interglacial (wetter, more C3) conditions. Intermediate herbivore δ13C values indicating mixed C3/C4 feeding is relatively rare, which we believe to reflect the abruptness of the transition between glacial and interglacial precipitation regimes in Sundaland. For seven Homo erectus bone samples we were not able distinguish between diagenetic overprint and original isotope values, underlining the need to apply this isotopic approach to Homo erectus tooth enamel instead of bone. Importantly, our present results on herbivore and omnivore faunas provide the isotopic framework that will allow interpretation of such Homo erectus enamel isotope data.

  1. 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.

  2. High-resolution profiling of the stable isotopes of water in unsaturated coal waste rock

    NASA Astrophysics Data System (ADS)

    Barbour, S. Lee; Hendry, M. Jim; Carey, Sean K.

    2016-03-01

    Characterization of the rate of water migration through unsaturated mine waste rock dumps is an essential element in assessing the chemical loading from these landforms; yet our understanding of how water moves into, through and out of waste rock is incomplete. To further understand the rates and magnitude of percolation through waste rock, deep high-resolution (every 0.1-4.5 m) depth profiles of the stable isotopes of water (δ2H and δ18O) at two coal waste rock dumps and a natural alluvial deposit down-gradient of one of the dumps were collected in the Elk Valley, British Columbia, Canada. The profiles were generated using vapor equilibrium techniques applied to continuous core samples collected using dry sonic drilling methods. Elevated core temperatures (up to 80 °C) were measured during sonic coring. The isotopic values of pore waters measured in the core samples were corrected for water loss to the atmosphere attributed to the elevated core temperatures. The average isotopic composition of the core samples were compared to water collected from rock drains discharging from the base of the dumps. The results indicate that high-resolution profiles of δ2H and δ18O can be measured to depths of 86 m in coal waste rock dumps and, based on the seasonal cycles in the isotopic composition of recharging water, can be used to characterize the migration of recharge water within these dumps. These profiles also suggest that recharge into these dumps occurs from both rain as well as snow melt and may be as high as 400-600 mm/yr (60-75% of annual precipitation). Combined with the relatively low volumetric water contents of these dumps (5-10%) the rates of water migration through the dumps are tens of meters each year.

  3. Interpreting the role of pH on stable isotopes in large benthic foraminifera

    USGS Publications Warehouse

    Robbins, Lisa L.; Knorr, P.O.; Wynn, J.G.; Hallock, P.; Harries, P.

    2016-01-01

    Large benthic foraminifera (LBF) are prolific producers of calcium carbonate sediments in shallow, tropical environments that are being influenced by ocean acidification (OA). Two LBF species, Amphistegina gibbosa (Order Rotaliida) with low-Mg calcite tests and Archaias angulatus (Order Miliolida) with high-Mg calcite tests, were studied to assess the effects of pH 7.6 on oxygen and carbon isotopic fractionation between test calcite and ambient seawater. The δ18O and δ13C values of terminal chambers and of whole adult tests of both species after 6 weeks were not significantly different between pH treatments of 8.0 and 7.6. However, tests of juveniles produced during the 6-week treatments showed significant differences between δ18O and δ13C values from control (pH 8.0) when compared with the treatment (pH 7.6) for both species. Although each individual's growth was photographed and measured, difficulty in distinguishing and manually extracting newly precipitated calcite from adult specimens likely confounded any differences in isotopic signals. However, juvenile specimens that resulted from asexual reproduction that occurred during the experiments did not contain old carbonate that could confound the new isotopic signals. These data reveal a potential bias in the design of OA experiments if only adults are used to investigate changes in test chemistries. Furthermore, the results reaffirm that different calcification mechanisms in these two foraminiferal orders control the fractionation of stable isotopes in the tests and will reflect decreasing pH in seawater somewhat differently. .

  4. Golan Heights Groundwater Systems: Separation By REE+Y And Stable Isotopes

    NASA Astrophysics Data System (ADS)

    Siebert, C.; Geyer, S.; Knoeller, K.; Roediger, T.; Weise, S.; Dulski, P.; Moeller, P.; Guttman, J.

    2008-12-01

    In a semi-arid to arid country like Israel, all freshwater resources are under (over-) utilization. Particularly, the Golan Heights rank as one of the most important extraction areas of groundwater of good quality and quantity. Additionally the mountain range feed to a high degree the most important freshwater reservoir of Israel, the Sea of Galilee. Hence, knowing the sources and characters of the Golan Heights groundwater systems is an instantaneous demand regarding sustainable management and protection. Within the "German-Israeli-Jordanian-Palestinian Joint Research Program for the Sustainable Utilisation of Aquifer Systems", hundreds of water samples were taken from all over the Jordan-Dead Sea rift-system to understand groundwater flow-systems and salinisation. For that purpose, each sample was analysed for major and minor ions, rare earth elements including yttrium (REY) and stable isotopes of water (d18O, d2H). The REY distribution in groundwater is established during infiltration by the first water-rock interaction and consequently reflects the leachable components of sediments and rocks of the recharge area. In well- developed flow-systems, REY are adsorbed onto pore surfaces are in equilibrium with the percolating groundwater, even if the lithology changes (e.g. inter-aquifer flow). Thus, groundwater sampled from wells and springs still show the REY distribution pattern established in the recharge area. Since high temperatures do not occur in Golan Heights, d2H and d18O are less controlled by water-rock interaction than by climatic and geomorphological factors at the time of replenishment. Applying the REY signature as a grouping criterion of groundwaters, d18O vs. d2H plots yield a new dimension in interpreting isotope data. The combined use of hydrochemical and isotopic methods enabled us to contain the areas of replenishment and the flow-paths of all investigated groundwater in the Golan Heights. Despite location, salinity or temperature of spring or

  5. Water isotope ratio (δ2H and δ18O) measurements in atmospheric moisture using an optical feedback cavity enhanced absorption laser spectrometer

    NASA Astrophysics Data System (ADS)

    Iannone, Rosario Q.; Romanini, Daniele; Cattani, Olivier; Meijer, Harro A. J.; Kerstel, Erik R. Th.

    2010-05-01

    Water vapor isotopes represent an innovative and excellent tool for understanding complex mechanisms in the atmospheric water cycle over different time scales, and they can be used for a variety of applications in the fields of paleoclimatology, hydrology, oceanography, and ecology. We use an ultrasensitive near-infrared spectrometer, originally designed for use on airborne platforms in the upper troposphere and lower stratosphere, to measure the water deuterium and oxygen-18 isotope ratios in situ, in ground-level tropospheric moisture, with a high temporal resolution (from 300 s down to less than 1 s). We present some examples of continuous monitoring of near-surface atmospheric moisture, demonstrating that our infrared laser spectrometer could be used successfully to record high-concentration atmospheric water vapor mixing ratios in continuous time series, with a data coverage of ˜90%, interrupted only for daily calibration to two isotope ratio mass spectrometry-calibrated local water standards. The atmospheric data show that the water vapor isotopic composition exhibits a high variability that can be related to weather conditions, especially to changes in relative humidity. Besides, the results suggest that observed spatial and temporal variations of the stable isotope content of atmospheric water vapor are strongly related to water vapor transport in the atmosphere.

  6. Precipitation source inferred from stable isotopic composition of Pleistocene groundwater and carbonate deposits in the western desert of Egypt.

    SciTech Connect

    Sultan, M.; Sturchio, N.; Hassan, F. A.; Abdel, M.; Hamdan, R.; Mahmood, A. M.; Alfy, Z. E.; Stein, T.; Environmental Research; Univ. Coll. London; Cairo Univ.; Ain Shams Univ.; Egyptian Geological survey and Mining Authority; Washington Univ.

    1997-01-01

    An Atlantic source of precipitation can be inferred from stable isotopic data (H and O) for fossil groundwaters and uranium-series-dated carbonate spring deposits from oases in the Western Desert of Egypt. In the context of available stable isotopic data for fossil groundwaters throughout North Africa, the observed isotopic depletions ({delta}D -72 to -81{per_thousand}; {delta}{sup 18}O -10.6 to -11.5{per_thousand}) of fossil ({ge}32,000 yr B.P.) groundwaters from the Nubian aquifer are best explained by progressive condensation of water vapor from paleowesterly wet oceanic air masses that traveled across North Africa and operated at least as far back as 450,000 yr before the present. The values of {delta}{sup 18}O (17.1 to 25.9{per_thousand}) for 45,000- to >450,000-yr-old tufas and vein-filling calcite deposits from the Kharga and Farafra Oases are consistent with deposition from groundwaters having oxygen isotopic compositions similar to those of fossil groundwaters sampled recently at these locations.

  7. 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

    2016-02-02

    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.

  8. A comparison of stable isotope data with pollen and ostracod faunal data in paleoclimate reconstruction

    NASA Astrophysics Data System (ADS)

    Rogers, Karel L.

    Sediments from 2300 m elevation in south-central Colorado and dating from 2.6-0.6 Ma have been recovered from surface outcrops and by core drilling. Three types of data (biogenic and inorganic stable isotope, pollen, and ostracod faunal) contributing to the two million year climatic record from this locality are compared against one another. Vadose zone carbonate δ13C values are used to infer July minimum temperatures from percent of grasses using the C4 photosynthetic pathway. The inferred temperatures are consistent with the occurrence of Limnocythere bradburyi, an ostracod that lives today only south of the frostline in North America. Biogenic carbonate δ13C data are interpreted as a measure of surface runoff, and δ18O data as a measure of evaporation/precipitation. Stable isotope data are significantly different between temperature sensitive species of ostracods, and less significant between salinity-sensitive species of ostracods. Biogenic isotope data are most negative when the abundance of Picea, Pinus, and Artemisia pollen indicates glaciation. The climate reconstruction derived from the combined interpretations of the Hansen Bluff data is in agreement with details of marine and terrestrial climatic records. Two major shifts in climate are apparent, one to more evaporative conditions at about 1.6 Ma and another toward cold, wet, glacial conditions starting at about 0.90 Ma.

  9. Growth decline and divergent tree ring isotopic composition (δ(13) C and δ(18) O) contradict predictions of CO2 stimulation in high altitudinal forests.

    PubMed

    Gómez-Guerrero, Armando; Silva, Lucas C R; Barrera-Reyes, Miguel; Kishchuk, Barbara; Velázquez-Martínez, Alejandro; Martínez-Trinidad, Tomás; Plascencia-Escalante, Francisca Ofelia; Horwath, William R

    2013-06-01

    Human-induced changes in atmospheric composition are expected to affect primary productivity across terrestrial biomes. Recent changes in productivity have been observed in many forest ecosystems, but low-latitude upper tree line forests remain to be investigated. Here, we use dendrochronological methods and isotopic analysis to examine changes in productivity, and their physiological basis, in Abies religiosa (Ar) and Pinus hartwegii (Ph) trees growing in high-elevation forests of central Mexico. Six sites were selected across a longitudinal transect (Transverse Volcanic Axis), from the Pacific Ocean toward the Gulf of Mexico, where mature dominant trees were sampled at altitudes ranging from 3200 to 4000 m asl. A total of 60 Ar and 84 Ph trees were analyzed to describe changes in growth (annual-resolution) and isotopic composition (decadal-resolution) since the early 1900s. Our results show an initial widespread increase in basal area increment (BAI) during the first half of the past century. However, BAI has decreased significantly since the 1950s with accentuated decline after the 1980s in both species and across sites. We found a consistent reduction in atmosphere to wood (13) C discrimination, resulting from increasing water use efficiency (20-60%), coinciding with rising atmospheric CO2 . Changes in (13) C discrimination were not followed, however, by shifts in tree ring δ(18) O, indicating site- and species-specific differences in water source or uptake strategy. Our results indicate that CO2 stimulation has not been enough to counteract warming-induced drought stress, but other stressors, such as progressive nutrient limitation, could also have contributed to growth decline. Future studies should explore the distinct role of resource limitation (water vs. nutrients) in modulating the response of high-elevation ecosystems to atmospheric change.

  10. Stable carbon and oxygen isotopes reveal Sahel drought events and ground water fluctuations in sub-Saharan Africa

    NASA Astrophysics Data System (ADS)

    Gebrekirstos, Aster

    2014-05-01

    Tree rings are important proxies for paleoclimate studies because they contain continuous historical records of inter-annual and intra-annual time resolutions, which range over hundreds of years. This study uses stable carbon and oxygen isotopes in tree rings to understand the drivers and impacts of climate change in sub-Saharan Africa and their ability to reconstruct past regional climate variability and climatic trends. Our approach considers large scale climate gradients and different temporal scales (inter-annual and intra-annual variations) and combines multi- parameter measurements (carbon and oxygen isotopes, whole wood and cellulose measurements). The study species are Faidherbia albida and Sclerocarya birrea from south and West Africa, respectively. Both are very important deciduous trees, and widely distributed in sub-Saharan Africa. Particularly, F. albida has a distinctive phenology; it bears leaves and flowers during the dry season and sheds its leaves during the rainy season. Stable carbon (δ13C) and oxygen (δ18O) mean values showed similar inter annual patterns. In general, both δ13C and δ18O show negative correlations with rainfall, humidity and PDSI. On the contrary, they are positively correlated with sunshine hours, maximum temperature and evaporation. The reverse phenology of Faidherbia and intra seasonal resolution measurements reveals seasonal ground water fluctuations. Both carbon and oxygen stable isotopes showed strong climatic signals including the long Sahel drought events and climatic recovery phases.

  11. A combined radio- and stable-isotopic study of a California coastal aquifer system

    USGS Publications Warehouse

    Swarzenski, Peter W.; Baskaran, Mark; Rosenbauer, Robert J.; Edwards, Brian D.; Land, Michael

    2013-01-01

    Stable and radioactive tracers were utilized in concert to characterize geochemical processes in a complex coastal groundwater system and to provide constraints on the kinetics of rock/water interactions. Groundwater samples from wells within the Dominguez Gap region of Los Angeles County, California were analyzed for a suite of major cations (Na+, K+, Mg2+, Ca2+) and anions (Cl−, SO42−), silica, alkalinity, select trace elements (Ba, B, Sr), dissolved oxygen, stable isotopes of hydrogen (δD), oxygen (δ18O), dissolved inorganic carbon (δ13CDIC), and radioactive isotopes (3H, 222Rn and 223,224,226,228Ra). In the study area, groundwater may consist of a complex mixture of native groundwater, intruded seawater, non-native injected water, and oil-field brine water. In some wells, Cl− concentrations attained seawater-like values and in conjunction with isotopically heavier δ18O values, these tracers provide information on the extent of seawater intrusion and/or mixing with oil-field brines. Groundwater 3H above 1 tritium unit (TU) was observed only in a few select wells close to the Dominguez Gap area and most other well groundwater was aged pre-1952. Based on an initial 14C value for the study site of 90 percent modern carbon (pmc), groundwater age estimates likely extend beyond 20 kyr before present and confirm deep circulation of some native groundwater through multiple aquifers. Enriched values of groundwater δ13CDIC in the absence of SO42− imply enhanced anaerobic microbial methanogenesis. While secular equilibrium was observed for 234U/238U (activity ratios ~1) in host matrices, strong isotopic fractionation in these groundwater samples can be used to obtain information of adsorption/desorption kinetics. Calculated Ra residence times are short, and the associated desorption rate constant is about three orders of magnitude slower than that of the adsorption rate constant. Combined stable- and radio-isotopic results provide unique insights into aquifer

  12. Late Quaternary Environmental Changes Inferred from the stable Oxygen Isotope Composition of Aquatic Insects (Chironomidae: Diptera) and Stable Hydrogen Isotope Composition of bulk sediments from Idavain Lake, Southwest Alaska

    NASA Astrophysics Data System (ADS)

    Wang, Y.; Finney, B.; Wooller, M. J.

    2007-12-01

    Several techniques are available to examine the isotopic composition of historic lake waters, providing data that can subsequently be used to examine environmental changes. Recently-developed techniques are the stable oxygen isotope analysis of subfossil chironomid (Diptera: Chironomidae) head capsules (mostly chitin) preserved in lake sediments and stable hydrogen isotope analyses directly on bulk sediments. An advantage of using δ18O of chironomids is that the chitinous chironomid headcapsules preserve well in lake sediments, retaining the stable oxygen isotope signature of the lake in which they lived. An advantage of δD analyses of bulk sediments is that a sediment core can be analyzed relatively easily and when the %C (total organic carbon) and %H profiles correlate the data can be used to infer past δD changes of the organics in the sediments. We present results from these analyses of a lake sediment core from Idavain Lake (58°46'N, 155°57'W, 223m above sea level) in southwest Alaska in concert with other paleolimnological proxies, including δ15N, δ13C, LOI, magnetic susceptibility, organic content and opal concentrations for a better understanding of paleolimnological changes since deglaciation for the region. Our preliminilary result shows that downcore shifts of δ18O analyzed from chironomid head capsules coincide well with LOI and pollen changes. The δD of sediments and TOM showed large magnitude changes and reflected the relative lake level changes during the record. This study aim to test the correlation between stable isotope analyese on chiornomid head capsules, lake water, and bulk sediments. In the addition, our study will add to the relatively small database of paleoenvironmental reconstructions from terrestrial sites in Southwest Alaska.

  13. Use of Stable Isotopes in Forensic Analysis of Microorganisms

    SciTech Connect

    Kreuzer-Martin, Helen W.; Hegg, Eric L.

    2012-01-18

    The use of isotopic signatures for forensic analysis of biological materials is well-established, and the same general principles that apply to interpretation of stable isotope content of C, N, O, and H apply to the analysis of microorganisms. Heterotrophic microorganisms derive their isotopic content from their growth substrates, which are largely plant and animal products, and the water in their culture medium. Thus the isotope signatures of microbes are tied to their growth environment. The C, N, O, and H isotope ratios of spores have been demonstrated to constitute highly discriminating signatures for sample matching. They can rule out specific samples of media and/or water as possible production media, and can predict isotope ratio ranges of the culture media and water used to produce a given sample. These applications have been developed and tested through analyses of approximately 250 samples of Bacillus subtilis spores and over 500 samples of culture media, providing a strong statistical basis for data interpretation. A Bayesian statistical framework for integrating stable isotope data with other types of signatures derived from microorganisms has been able to characterize the culture medium used to produce spores of various Bacillus species, leveraging isotopic differences in different medium types and demonstrating the power of data integration for forensic investigations.

  14. Temporal and Spatial Variation of Surface Water Stable Isotopes in the Marys River Basin, Oregon

    NASA Astrophysics Data System (ADS)

    Nickolas, L. B.; Segura, C.; Brooks, J. R.

    2015-12-01

    Understanding the temporal and spatial variability of water sources within a basin is vital to our ability to manage the impacts of climate variability and land cover change. Water stable isotopes can be used as a tool to determine geographic and seasonal sources of water at the basin scale. Previous studies in the Coastal Range of Oregon reported that the variation in the isotopic signatures of surface water does not conform to the commonly observed "rainout effect", which exhibits a trend of increasing isotopic depletion with rising elevation. The primary purpose of this research is to investigate the mechanisms governing seasonal and spatial variations in the isotopic signature of surface waters within the Marys River Basin, located in the Oregon Coastal Range. We hypothesize that catchment orientation, drainage area, geology, and topography act as controlling factors on groundwater flow, storage, and atmospheric moisture cycling, which explain variations in source water contribution. Surface water and precipitation samples were collected every 2-3 weeks for isotopic analysis of δ18O and δ2H for one year. Preliminary results indicate a significant difference (p<0.001) in isotopic signature between watersheds underlain by basalt and sandstone. The degree of separation is the most distinct during the summer when low flows likely reflect deeper groundwater sources, whereas isotopic signatures during the rainy season (fall & winter) show a greater degree of similarity between the two lithologies. These findings indicate that the more permeable sandstone formations may be hydrologically connected to enriched water sources on the windward side of the Coastal Range that sustain baseflow within catchments on the leeward side, while streams draining basalt catchments are fed by a more depleted source of water (e.g. precipitation originating within the Marys River Basin).

  15. Stable Isotope Ratios and the Forensic Analysis of Microorganisms

    SciTech Connect

    Kreuzer-Martin, Helen W.; Jarman, Kristin H.

    2007-06-01

    In the aftermath of the anthrax letters of 2001, researchers have been exploring various analytical signatures for the purpose of characterizing the production environment of microorganisms. One such signature is stable isotope ratios, which in heterotrophs are a function of nutrient and water sources. Here we discuss the use of stable isotope ratios in microbe forensics, using as a database the carbon, nitrogen, oxygen and hydrogen stable isotope ratios of 247 separate cultures of B. subtilis 6051 spores produced on a total of 32 different culture media. In the context of using stable isotope ratios as a signature for sample matching, we present an analysis of variation between individual samples, between cultures produced in tandem, and between cultures produced in the same medium but at different times. Additionally, we correlate the stable isotope ratios of carbon, nitrogen, oxygen, and hydrogen for growth medium nutrients or water with those of spores and show examples of how these relationships can be used to exclude nutrient or water samples as possible growth substrates for specific cultures.

  16. Stable isotopic (O, H) evidence for hydration of the central Colorado Plateau lithospheric mantle by slab-derived fluids

    NASA Astrophysics Data System (ADS)

    Marshall, E. W.; Barnes, J.; Lassiter, J. C.

    2013-12-01

    The Colorado Plateau is a tectonically stable, relatively undeformed Proterozoic lithospheric province in the North America Cordillera. Although the stability of the Colorado Plateau suggests that it is rheologically strong, evidence from xenoliths show that the lithospheric mantle is extensively hydrated (e.g., presence of hydrous minerals, 'high' water contents in nominally anhydrous minerals), and therefore weakened. In addition, LREE enrichments in clinopyroxene (cpx) imply that the lithospheric mantle has been metasomatized ([1],[2]). Here we analyze mineral separates from spinel and garnet peridotite xenoliths from the Navajo Volcanic Field (NVF), located in the center of the Plateau, for their oxygen and hydrogen isotope compositions. These compositions are compared to those of xenoliths at the margins of the Plateau: spinel peridotites from the Grand Canyon Volcanic Field (GCVF) in the west and Zuni-Bandera Volcanic Field (ZBVF) in the east. NVF xenoliths are significantly more hydrous than the xenoliths on the margins of the Colorado Plateau based on modal abundances of hydrous minerals and structural water in olivine (e.g. [3]). All hydrous phases have high δD values (antigorite = -71 to -46‰ (n = 6 xenoliths); chlorite = -49 to -31‰ (n=3); amphibole = -47‰ (n=1)) compared to normal mantle (~-80‰), suggesting the addition of a fluid that is enriched in D compared to typical mantle. δ18O values for the same hydrous minerals range from 6.0 to 6.6‰ (n=6). δ18O values of olivine from NVF spinel peridotites have a narrow range, 5.0 to 5.4‰ (n = 4), near mantle olivine values (~5.2‰). Olivines from spinel peridotites from the GCVF and ZBVF also have mantle-like δ18O values (5.1 to 5.2‰ (n=3) and 5.1 to 5.4‰ (n=7), respectively). However, olivines and orthopyroxenes (opx) from NVF garnet peridotites have a slightly larger range and some record 18O enrichment (olivine = 5.1 to 5.6‰ (n = 3); opx = 5.9‰ (n=1)). The high δ18O values of

  17. Oxygen isotope ratios and rare earth elements in 3.3 to 4.4 Ga zircons: Ion microprobe evidence for high δ 18O continental crust and oceans in the Early Archean

    NASA Astrophysics Data System (ADS)

    Peck, William H.; Valley, John W.; Wilde, Simon A.; Graham, Colin M.

    2001-11-01

    Ion microprobe analyses of oxygen isotope ratios in Early Archean (Hadean) zircons (4.0- to 4.4-Ga) reveal variable magmatic δ 18O values, including some that are high relative to the mantle, suggesting interaction between magmas and already-formed continental crust during the first 500 million yr of Earth's history. The high average δ 18O value of these zircons is confirmed by conventional analysis. A metaconglomerate from the Jack Hills in the Yilgarn Craton (Western Australia) contains detrital zircons with ages > 4.0 Ga (Compston and Pidgeon, 1986) and one crystal that is 4.40-Ga old (Wilde et al., 2001). The newly discovered 4.40-Ga grain is the oldest recognized terrestrial mineral. The Jack Hills metaconglomerate also contains a large 3.3- to 3.6-Ga-old zircon population with an average δ 18O value of 6.3 ± 0.1‰ (1 s.e.,; n = 32 spot analyses). Two 4.15-Ga zircons have an average δ 18O of 5.7 ± 0.2‰ ( n = 13). In addition, a 4.13-Ga zircon has an average δ 18O of 7.2 ± 0.3‰ ( n = 8) and another 4.01-Ga zircon has an average δ 18O of 6.8 ± 0.4‰ ( n = 10). The oldest grain (4.40 Ga) is zoned with respect trace element composition (especially LREE), and intensity of cathodoluminescence, all of which correlate with oxygen isotope ratios (7.4‰ vs. 5.0‰). High LREE and high-δ 18O values from the 4.01- to 4.40-Ga grains are consistent with growth in evolved granitic magmas (δ 18O(WR) = 8.5 to 9.5‰) that had interacted with supracrustal materials. High δ 18O values show that low-temperature surficial processes (i.e., diagenesis, weathering, or low-temperature alteration) occurred before 4.0 Ga, and even before 4.40 Ga, shortly following the hypothesized date of core differentiation and impact of a Mars-sized body to form the Moon at ˜4.45 Ga. This is the first evidence of continental crust as early as 4.40 Ga and suggests differentiation during the period of intense meteorite bombardment of the early Earth. The magnitude of water and rock

  18. Multi-decadal carbon and water relations of African tropical humid forests: a tree-ring stable isotope analysis

    NASA Astrophysics Data System (ADS)

    Hufkens, Koen; Helle, Gerd; Beeckman, Hans; de Haulleville, Thales; Kearsley, Elizabeth; Boeckx, Pascal

    2013-04-01

    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 seasonally 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/12C and 18O/16O isotopes also reveal the environmental conditions in which the trees were growing. In particular, stable isotope ratios in tree-rings of carbon are influenced by fractionation through carboxylation during photosynthesis and changes in leaf stomatal conductance. Similarly, fractionation of oxygen isotopes of soil water occurs at the leaf level through evapo-transipiration. As a consequence, 18O/16O (δ18O) values in wood cores will reflect both the signal of the source water as well as that of for example summer humidity. Therefore, both C and O stable isotopes might not only be valuable as proxy data for past climatic conditions but they also serve as an important tool in understanding carbon and water relations within a tropical 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 composition(δ13C , δ18O) at a tropical humid forests in the DR Congo. The Yangambi Man And Biosphere (MAB) reserve is located in the north-eastern part of DR Congo, with a distinct tropical rainforest climate. In addition to the tree-core data records and

  19. Late Pliocene - Early Pleistocene paleoenvironmental reconstruction based on stable isotope compositions of Stephanorhinus sp. and Mammut sp. teeth

    NASA Astrophysics Data System (ADS)

    Szabó, Péter; Kovács, János; Kocsis, László; Gasparik, Mihály; Vennemann, Torsten; Demény, Attila; Virág, Attila

    2014-05-01

    Stable isotope measurements of skeletal apatite from herbivorous mammals are often used to provide information on the terrestrial paleoenvironment and paleoclimate. In this study fossil teeth of Stephanorhinus Kretzoi 1942 (rhinoceros) and Mammut Blumenbach 1799 (mastodon), amongst others, were investigated from the Carpathian Basin. According to the biostratigraphy, the age of the samples has a range from Late Pliocene to Early Pleistocene. Reconstructing paleoclimate and paleoenvironment of this era is important as it can be an analogue for the future climate. Oxygen and carbon isotopic compositions were measured from the tooth enamel, because it is believed to be the most resistant to diagenetic alteration (e.g., Kohn & Cerling, 2002). The carbon isotopic composition in the carbonate fraction of apatite can be related to the diet of the animal (Kohn & Cerling, 2002). Hence, it can reflect the photosynthetic pathway (C3 or C4) of the plants consumed by these herbivores. The δ18O values were determined in the phosphate fraction of apatite. In the case of large mammals that are obligate drinkers, the δ18O values closely track those of the environmental water (Bryant & Froelich, 1995). Knowing the δ18O values of environmental water and relating it to local precipitation, the mean annual temperature (MAT) of the site can be calculated (Dansgaard, 1964). The δ13C values range from -10 to -15 o (VPDB). The result clearly shows that these animals consumed C3 plants. Most of the δ13C values indicate mixed grassland-open woodland rather than a closed canopy forest. Although there is variation in the δ18O values (mean 14.2 ± 1.0 o VSMOW, n=17), most of the samples would support a MAT range of 8-12 ° C. This is in good agreement with other proxies for the localities and time period (Kovács et al., 2013). Bryant, D.J. & Froelich, P.N. (1995) A model of oxygen-isotope fractionation in bodywater of large-mammals. Geochimica et Cosmochimica Acta 59, 4523

  20. 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.

  1. Photosynthetic fractionation of the stable isotopes of oxygen and carbon

    SciTech Connect

    Guy, R.D. ); Fogel, M.L.; Berry, J.A. )

    1993-01-01

    Isotope discrimination during photosynthetic exchange of O[sub 2] and CO[sub 2] was measured using enzyme, thylakoid, and whole cell preparations. Evolved oxygen from isolated spinach thylakoids was isotopically identical (within analytical error) to its source water. Similar results were obtained with Anacystis nidulans Richter and Phaeodactylum tricornutum Bohlin cultures purged with helium. For consumptive reactions, discrimination ([triangle], where 1 + [triangle]/1000 equals the isotope effect, k[sup 16]/k[sup 18] or k[sup 12]/k[sup 13]) was determined by analysis of residual substrate (O[sub 2] or CO[sub 2]). The [triangle] for the Mehler reaction, mediated by ferredoxin or methylviologen, was 15.3[per thousand]. Oxygen isotope discrimination during oxygenation of ribulose-1,5-bisphosphate (RuBP) catalyzed by RuBP carboxylase/oxygenase (Rubisco) was 21.3[per thousand] and independent of enzyme source, unlike carbon isotope dicrimination: 30.3[per thousand] for spinach enzyme and 19.6 to 23[per thousand] for Rhodospirillum rubrum and A. nidulans enzymes, depending on reaction conditions. The [triangle] for O[sub 2] consumption catalyzed by glycolate oxidase was 22.7[per thousand]. Consistent with this, when Asparagus sprengeri Regel mesopyll cells approached the compensation point within a sealed vessel, the [delta][sup 18]O of dissolved O[sub 2] came to a steady-state value of about 21.5[per thousand] relative to the source water. The results provide improved estimates of discrimination factors in several reactions prominent in the global oxygen cycle and indicate that photorespiration plays a significant part in determining the isotopic composition of atmospheric oxygen. 47 refs., 8 figs., 2 tabs.

  2. Photosynthetic Fractionation of the Stable Isotopes of Oxygen and Carbon.

    PubMed Central

    Guy, R. D.; Fogel, M. L.; Berry, J. A.

    1993-01-01

    Isotope discrimination during photosynthetic exchange of O2 and CO2 was measured using enzyme, thylakoid, and whole cell preparations. Evolved oxygen from isolated spinach thylakoids was isotopically identical (within analytical error) to its source water. Similar results were obtained with Anacystis nidulans Richter and Phaeodactylum tricornutum Bohlin cultures purged with helium. For consumptive reactions, discrimination ([delta], where 1 + [delta]/1000 equals the isotope effect, k16/k18 or k12/k13) was determined by analysis of residual substrate (O2 or CO2). The [delta] for the Mehler reaction, mediated by ferredoxin or methylviologen, was 15.3[per mille (thousand) sign]. Oxygen isotope discrimination during oxygenation of ribulose-1,5-bisphosphate (RuBP) catalyzed by RuBP carboxylase/oxygenase (Rubisco) was 21.3[per mille (thousand) sign] and independent of enzyme source, unlike carbon isotope discrimination: 30.3[per mille (thousand) sign] for spinach enzyme and 19.6 to 23[per mille (thousand) sign] for Rhodospirillum rubrum and A. nidulans enzymes, depending on reaction conditions. The [delta] for O2 consumption catalyzed by glycolate oxidase was 22.7[per mille (thousand) sign]. The expected overall [delta] for photorespiration is about 21.7[per mille (thousand) sign]. Consistent with this, when Asparagus sprengeri Regel mesophyll cells approached the compensation point within a sealed vessel, the [delta]18O of dissolved O2 came to a steady-state value of about 21.5[per mille (thousand) sign] relative to the source water. The results provide improved estimates of discrimination factors in several reactions prominent in the global O cycle and indicate that photorespiration plays a significant part in determining the isotopic composition of atmospheric oxygen. PMID:12231663

  3. Accuracy of delta 18O isotope ratio measurements on the same sample by continuous-flow isotope-ratio mass spectrometry

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The doubly labeled water method is considered the reference method to measure energy expenditure. Conventional mass spectrometry requires a separate aliquot of the same sample to be prepared and analyzed separately. With continuous-flow isotope-ratio mass spectrometry, the same sample could be analy...

  4. The origin of hydrous, high-δ18O voluminous volcanism: diverse oxygen isotope values and high magmatic water contents within the volcanic record of Klyuchevskoy volcano, Kamchatka, Russia

    NASA Astrophysics Data System (ADS)

    Auer, Sara; Bindeman, Ilya; Wallace, Paul; Ponomareva, Vera; Portnyagin, Maxim

    2009-02-01

    Klyuchevskoy volcano, in Kamchatka’s subduction zone, is one of the most active arc volcanoes in the world and contains some of the highest δ18O values for olivines and basalts. We present an oxygen isotope and melt inclusion study of olivine phenocrysts in conjunction with major and trace element analyses of 14C- and tephrochronologically-dated tephra layers and lavas spanning the eruptive history of Klyuchevskoy. Whole-rock and groundmass analyses of tephra layers and lava samples demonstrate that both high-Mg (7-12.5 wt% MgO) and high-Al (17-19 wt% Al2O3, 3-6.5 wt% MgO) basalt and basaltic andesite erupted coevally from the central vent and flank cones. Individual and bulk olivine δ18O range from normal MORB values of 5.1‰ to values as high as 7.6‰. Likewise, tephra and lava matrix glass have high-δ18O values of 5.8-8.1‰. High-Al basalts dominate volumetrically in Klyuchevskoy’s volcanic record and are mostly high in δ18O. High-δ18O olivines and more normal-δ18O olivines occur in both high-Mg and high-Al samples. Most olivines in either high-Al or high-Mg basalts are not in oxygen isotopic equilibrium with their host glasses, and Δ18Oolivine-glass values are out of equilibrium by up to 1.5‰. Olivines are also out of Fe-Mg equilibrium with the host glasses, but to a lesser extent. Water concentrations in olivine-hosted melt inclusions from five tephra samples range from 0.4 to 7.1 wt%. Melt inclusion CO2 concentrations vary from below detection (<50 ppm) to 1,900 ppm. These values indicate depths of crystallization up to ~17 km (5 kbar). The variable H2O and CO2 concentrations likely reflect crystallization of olivine and entrapment of inclusions in ascending and degassing magma. Oxygen isotope and Fe-Mg disequilibria together with melt inclusion data indicate that olivine was mixed and recycled between high-Al and high-Mg basaltic melts and cumulates, and Fe-Mg and δ18O re-equilibration processes were incomplete. Major and trace elements in

  5. Stable platinum isotope measurements in presolar nanodiamonds by TEAMS

    PubMed Central

    Wallner, A.; Melber, K.; Merchel, S.; Ott, U.; Forstner, O.; Golser, R.; Kutschera, W.; Priller, A.; Steier, P.

    2013-01-01

    Nanodiamonds are stardust grains commonly found in primitive meteorites. They survived the formation of the solar system and kept their own individuality. Measurements of trace-element isotopic signatures in these grains will help understanding heavy element nucleosynthesis in massive stars and dust formation from their ejecta. We have continued previous attempts to search for stable Pt isotope anomalies in nanodiamonds via trace element accelerator mass spectrometry (TEAMS). The installation of a new injector beam line at the VERA facility allowed studying low traces of stable elements in different materials. Moreover, recent experiments showed that VERA provides the required measurement precision together with a low Pt machine background. Here, we observed for the first time an indication for enhancements of 198Pt/195Pt isotope ratios in two diamond residues prepared by different chemical separation techniques from the Allende meteorite. Variations in other isotopic ratios were within analytical uncertainty, and no anomaly was identified in a third diamond fraction. PMID:23565017

  6. Coupling stable isotopes with bioenergetics to estimate interspecific interactions.

    PubMed

    Caut, Stephane; Roemer, Gary W; Donlan, C Josh; Courchamp, Franck

    2006-10-01

    Interspecific interactions are often difficult to elucidate, particularly with large vertebrates at large spatial scales. Here, we describe a methodology for estimating interspecific interactions by combining stable isotopes with bioenergetics. We illustrate this approach by modeling the population dynamics and species interactions of a suite of vertebrates on Santa Cruz Island, California, USA: two endemic carnivores (the island fox and island spotted skunk), an exotic herbivore (the feral pig), and their shared predator, the Golden Eagle. Sensitivity analyses suggest that our parameter estimates are robust, and natural history observations suggest that our overall approach captures the species interactions in this vertebrate community. Nonetheless, several factors provide challenges to using isotopes to infer species interactions. Knowledge regarding species-specific isotopic fractionation and diet breadth is often lacking, n