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Sample records for delta 15n values

  1. Individual protein balance strongly influences delta15N and delta13C values in Nile tilapia, Oreochromis niloticus.

    Science.gov (United States)

    Gaye-Siessegger, Julia; Focken, Ulfert; Abel, Hansjörg; Becker, Klaus

    2004-02-01

    Although stable isotope ratios in animals have often been used as indicators of the trophic level and for the back-calculation of diets, few experiments have been done under standardized laboratory conditions to investigate factors influencing delta(15)N and delta(13)C values. An experiment using Nile tilapia [ Oreochromis niloticus (L.)] was therefore carried out to test the effect of different dietary protein contents (35.4, 42.3, and 50.9%) on delta(15)N and delta(13)C values of the whole tilapia. The fish were fed the isoenergetic and isolipidic semi-synthetic diets at a relatively low level. delta(15)N and delta(13)C values of the lipid-free body did not differ between the fish fed the diets with different protein contents, but the trophic shift for N and C isotopes decreased with increasing protein accretion in the individual fish, for N from 6.5 per thousand to 4 per thousand and for C in the lipid-free body from 4 per thousand to 2.5 per thousand. This is the first study showing the strong influence of the individual protein balance to the degree to which the isotopic signature of dietary protein was modified in tissue protein of fish. The extrapolation of the trophic level or the reconstruction of the diet of an animal from stable isotope ratios without knowledge of the individual physiological condition and the feeding rate may lead to erroneous results.

  2. Delta15N values of tropical savanna and monsoon forest species reflect root specialisations and soil nitrogen status.

    Science.gov (United States)

    Schmidt, S; Stewart, G R

    2003-03-01

    A large number of herbaceous and woody plants from tropical woodland, savanna, and monsoon forest were analysed to determine the impact of environmental factors (nutrient and water availability, fire) and biological factors (microbial associations, systematics) on plant delta(15)N values. Foliar delta(15)N values of herbaceous and woody species were not related to growth form or phenology, but a strong relationship existed between mycorrhizal status and plant delta(15)N. In woodland and savanna, woody species with ectomycorrhizal (ECM) associations and putative N(2)-fixing species with ECM/arbuscular (AM) associations had lowest foliar delta(15)N values (1.0-0.6 per thousand ), AM species had mostly intermediate delta(15)N values (average +0.6 per thousand ), while non-mycorrhizal Proteaceae had highest delta(15)N values (+2.9 to +4.1 per thousand ). Similar differences in foliar delta(15)N were observed between AM (average 0.1 and 0.2 per thousand ) and non-mycorrhizal (average +0.8 and +0.3 per thousand ) herbaceous species in woodland and savanna. Leguminous savanna species had significantly higher leaf N contents (1.8-2.5% N) than non-fixing species (0.9-1.2% N) indicating substantial N acquisition via N(2) fixation. Monsoon forest species had similar leaf N contents (average 2.4% N) and positive delta(15)N values (+0.9 to +2.4 per thousand ). Soil nitrification and plant NO(3)(-) use was substantially higher in monsoon forest than in woodland or savanna. In the studied communities, higher soil N content and nitrification rates were associated with more positive soil delta(15)N and plant delta(15)N. In support of this notion, Ficus, a high NO(3)(-) using taxa associated with NO(3)(-) rich sites in the savanna, had the highest delta(15)N values of all AM species in the savanna. delta(15)N of xylem sap was examined as a tool for studying plant delta(15)N relations. delta(15)N of xylem sap varied seasonally and between differently aged Acacia and other savanna

  3. Influence of different organic fertilizers on quality parameters and the delta(15)N, delta(13)C, delta(2)H, delta(34)S, and delta(18)O values of orange fruit (Citrus sinensis L. Osbeck).

    Science.gov (United States)

    Rapisarda, Paolo; Camin, Federica; Fabroni, Simona; Perini, Matteo; Torrisi, Biagio; Intrigliolo, Francesco

    2010-03-24

    To investigate the influence of different types of fertilizers on quality parameters, N-containing compounds, and the delta(15)N, delta(13)C, delta(2)H, delta (34)S, and delta(18)O values of citrus fruit, a study was performed on the orange fruit cv. 'Valencia late' (Citrus sinensis L. Osbeck), which was harvested in four plots (three organic and one conventional) located on the same farm. The results demonstrated that different types of organic fertilizers containing the same amount of nitrogen did not effect important changes in orange fruit quality parameters. The levels of total N and N-containing compounds such as synephrine in fruit juice were not statistically different among the different treatments. The delta(15)N values of orange fruit grown under fertilizer derived from animal origin as well as from vegetable compost were statistically higher than those grown with mineral fertilizer. Therefore, delta(15)N values can be used as an indicator of citrus fertilization management (organic or conventional), because even when applied organic fertilizers are of different origins, the natural abundance of (15)N in organic citrus fruit remains higher than in conventional ones. These treatments also did not effect differences in the delta(13)C, delta(2)H, delta(34)S, and delta(18)O values of fruit.

  4. Anthropogenic nitrogen input traced by means of delta15N values in macroalgae: results from in-situ incubation experiments.

    Science.gov (United States)

    Deutsch, Barbara; Voss, Maren

    2006-08-01

    The macroalgae species Fucus vesiculosus (Phaeophyta), Polysiphonia sp., and Ceramium rubrum (Rhodophyta) originally grown at an unpolluted brackish site of the southern Baltic Sea were incubated for 10 and 14 days at 12 stations along a salinity gradient in a highly polluted estuary. We have expected an adaptation of the initially low delta15N values to the higher ones within the incubation period. In addition to the macroalgae the delta15N values of NO3(-) were measured to evaluate fractionation processes of the source nitrate. Inside the estuary, delta15N-NO3(-) values were 6.2-9.7 per thousand, indicating anthropogenic nitrogen sources. The red macroalgae adequately reflected the nitrate isotope values in the surrounding waters, whereas for F. vesiculosus the results were not that clear. The reasons were assumed to be higher initial delta15N values of F. vesiculosus and presumably a too slow nitrogen uptake and growth rate. The method of macroalgae incubations seems suitable as a simple monitoring to study the influence of anthropogenic nitrogen loading in an estuarine environment.

  5. Intraspecific variation in hair delta(13)C and delta(15)N values of ring-tailed lemurs (Lemur catta) with known individual histories, behavior, and feeding ecology.

    Science.gov (United States)

    Loudon, James E; Sponheimer, Matt; Sauther, Michelle L; Cuozzo, Frank P

    2007-07-01

    Stable carbon and nitrogen isotope compositions were analyzed from hair samples of 30 sympatric ring-tailed lemurs (Lemur catta) inhabiting the Beza Mahafaly Special Reserve, Madagascar. All lemurs were known individuals involved in a longitudinal study, which allowed us to explore the degree to which group membership, sex, health status, and migration influenced their stable isotope compositions. The differences in delta(13)C and delta(15)N values between groups were small (lemur conservation. There were few sex differences, but significant differences did occur between individuals of normal and suboptimal health, with those in poor health (especially those in the worst condition) being enriched in (15)N and to a lesser degree (13)C compared with healthy individuals. Moreover, lemurs that had emigrated between 2003 and 2004 had different delta(13)C and delta(15)N compositions than their original groups. (c) 2007 Wiley-Liss, Inc.

  6. delta 15N and non-carbonate delta 13C values for two petroleum source rock reference materials and a marine sediment reference material

    Science.gov (United States)

    Dennen, Kristin O.; Johnson, Craig A.; Otter, Marshall L.; Silva, Steven R.; Wandless, Gregory A.

    2006-01-01

    Samples of United States Geological Survey (USGS) Certified Reference Materials USGS Devonian Ohio Shale (SDO-1), and USGS Eocene Green River Shale (SGR-1), and National Research Council Canada (NRCC) Certified Marine Sediment Reference Material (PACS-2), were sent for analysis to four separate analytical laboratories as blind controls for organic rich sedimentary rock samples being analyzed from the Red Dog mine area in Alaska. The samples were analyzed for stable isotopes of carbon (delta13Cncc) and nitrogen (delta15N), percent non-carbonate carbon (Wt % Cncc) and percent nitrogen (Wt % N). SDO-1, collected from the Huron Member of the Ohio Shale, near Morehead, Kentucky, and SGR-1, collected from the Mahogany zone of the Green River Formation are petroleum source rocks used as reference materials for chemical analyses of sedimentary rocks. PACS-2 is modern marine sediment collected from the Esquimalt, British Columbia harbor. The results presented in this study are, with the exceptions noted below, the first published for these reference materials. There are published information values for the elemental concentrations of 'organic' carbon (Wt % Corg measured range is 8.98 - 10.4) and nitrogen (Wt % Ntot 0.347 with SD 0.043) only for SDO-1. The suggested values presented here should be considered 'information values' as defined by the NRCC Institute for National Measurement Reference Materials and should be useful for the analysis of 13C, 15N, C and N in organic material in sedimentary rocks.

  7. Anthropogenic nitrogen input traced by means of {delta} {sup 15}N values in macroalgae: Results from in-situ incubation experiments

    Energy Technology Data Exchange (ETDEWEB)

    Deutsch, Barbara [Baltic Sea Research Institute, Seestr. 15, 18119 Rostock (Germany)]. E-mail: barbara.deutsch@io-warnemuende.de; Voss, Maren [Baltic Sea Research Institute, Seestr. 15, 18119 Rostock (Germany)

    2006-08-01

    The macroalgae species Fucus vesiculosus (Phaeophyta), Polysiphonia sp., and Ceramium rubrum (Rhodophyta) originally grown at an unpolluted brackish site of the southern Baltic Sea were incubated for 10 and 14 days at 12 stations along a salinity gradient in a highly polluted estuary. We have expected an adaptation of the initially low {delta} {sup 15}N values to the higher ones within the incubation period. In addition to the macroalgae the {delta} {sup 15}N values of NO{sub 3} {sup -} were measured to evaluate fractionation processes of the source nitrate. Inside the estuary, {delta} {sup 15}N-NO{sub 3} {sup -} values were 6.2-9.7 per mille , indicating anthropogenic nitrogen sources. The red macroalgae adequately reflected the nitrate isotope values in the surrounding waters, whereas for F. vesiculosus the results were not that clear. The reasons were assumed to be higher initial {delta} {sup 15}N values of F. vesiculosus and presumably a too slow nitrogen uptake and growth rate. The method of macroalgae incubations seems suitable as a simple monitoring to study the influence of anthropogenic nitrogen loading in an estuarine environment.

  8. Coral skeletal {delta}{sup 15}N reveals isotopic traces of an agricultural revolution

    Energy Technology Data Exchange (ETDEWEB)

    Marion, Guy S. [Department of Biological Sciences, Stanford University, Stanford, CA 94305 (United States)]. E-mail: g.marion@uq.edu.au; Dunbar, Robert B. [Department of Geological and Environmental Sciences, Stanford University, Stanford, CA 94305 (United States); Mucciarone, David A. [Department of Geological and Environmental Sciences, Stanford University, Stanford, CA 94305 (United States); Kremer, James N. [Department of Marine Sciences, University of Connecticut at Avery Point, Groton, CT 06340 (United States); Lansing, J. Stephen [Department of Anthropology, University of Arizona, Tucson, AZ 85721 (United States); Arthawiguna, Alit [Installation for Agricultural Research (IP 2TP), Kotak Pos 3480, Denpasar, Bali (Indonesia)

    2005-09-01

    This study introduces a new method of tracing the history of nutrient loading in coastal oceans via {delta}{sup 15}N analysis of organic nitrogen preserved in the skeleton of the massive Porites coral. Four coral cores were collected in Bali, Indonesia, from reefs exposed to high levels of fertilizers in agricultural run-off, from lagoonal corals impacted by sewage, and from a reef located 30 km offshore. Skeletal {delta}{sup 15}N in the agriculturally exposed coral declined from 10.7 {+-} 0.4 per mille in 1970-1971, when synthetic fertilizers (-0.8 per mille {+-} 0.2 per mille ) were introduced to Bali, to a depleted 'anthropogenic' baseline of 3.5 per mille {+-} 0.4% in the mid-1990s. {delta}{sup 15}N values were negatively correlated with rainfall, suggesting that marine {delta}{sup 15}N lowers during flood-born influxes of waste fertilizers. Reef cores exposed to untreated sewage in terrestrial discharge were enriched (7.8 and 7.3 {+-} 0.4 per mille ), while the offshore core reflected background oceanic signals (6.2 {+-} 0.4 per mille). {delta}{sup 15}N, N concentration, and C:N systematics indicate that the N isotopic composition of skeletal organic matter was generally well preserved over 30 years. We suggest that skeletal organic {delta}{sup 15}N can serve as a recorder of past nitrogen sources. In Bali, this tracer suggests that the intensification of Western style agricultural practices since 1970 are contributing to the degradation of coastal coral reefs.

  9. Homogeneity of delta{sup 15}N in needles of Masson pine (Pinus massoniana L.) was altered by air pollution

    Energy Technology Data Exchange (ETDEWEB)

    Kuang Yuanwen, E-mail: kuangyw@scbg.ac.c [Institute of Ecology, South China Botanical Garden, Chinese Academy of Sciences, Guangzhou 510650 (China); Pearl River Delta Research Center of Environmental Pollution and Control, Chinese Academy of Sciences, Guangzhou 510650 (China); Wen Dazhi; Li Jiong [Institute of Ecology, South China Botanical Garden, Chinese Academy of Sciences, Guangzhou 510650 (China); Pearl River Delta Research Center of Environmental Pollution and Control, Chinese Academy of Sciences, Guangzhou 510650 (China); Sun Fangfang; Hou Enqing [Institute of Ecology, South China Botanical Garden, Chinese Academy of Sciences, Guangzhou 510650 (China); Graduate University of the Chinese Academy of Sciences, Beijing 100049 (China); Zhou Guoyi; Zhang Deqiang [Institute of Ecology, South China Botanical Garden, Chinese Academy of Sciences, Guangzhou 510650 (China); Huang Longbin [Centre for Mined Land Rehabilitation, Sustainable Minerals Institute, the University of Queensland, QLD 4072 (Australia)

    2010-05-15

    The present study investigated the changes of delta{sup 15}N values in the tip, middle and base section (divided by the proportion to needle length) of current- and previous-year needles of Masson pine (Pinus massoniana L.) from two declining forest stands suffering from air pollution, in comparison with one healthy stand. At the healthy stand, delta{sup 15}N in the three sections of both current- and previous-year needles were found evenly distributed, while at the polluted stands, delta{sup 15}N values in the needles were revealed significantly different from the tip to the base sections. The results implied that the distribution of delta{sup 15}N among different parts or sections in foliages was not always homogeneous and could be affected by air pollution. We suggested that the difference of delta{sup 15}N values among pine needle sections should be reconsidered and should not be primarily ignored when the needle delta{sup 15}N values were used to assess plant responses to air pollution. - Values of delta{sup 15}N in needles of Masson pine (Pinus massoniana L.) were uneven and affected by air pollution.

  10. Seasonal mercury concentrations and {delta}{sup 15}N and {delta}{sup 13}C values of benthic macroinvertebrates and sediments from a historically polluted estuary in south central Chile

    Energy Technology Data Exchange (ETDEWEB)

    Diaz-Jaramillo, Mauricio, E-mail: mdiazjaramillo@conicet.gov.ar [Aquatic Systems Research Unit, EULA Chile Environmental Sciences Centre, Universidad de Concepcion (Chile); Munoz, Claudia; Rudolph, Ignacio [Aquatic Systems Research Unit, EULA Chile Environmental Sciences Centre, Universidad de Concepcion (Chile); Servos, Mark [Department of Biology, University of Waterloo, ON (Canada); Barra, Ricardo [Aquatic Systems Research Unit, EULA Chile Environmental Sciences Centre, Universidad de Concepcion (Chile)

    2013-01-01

    The Lenga Estuary is one of the most industrialized sites in south central Chile where the historic operation of chlor-alkali plants resulted in large quantities of mercury (Hg) being deposited into the estuary. This historical contamination may still represent a risk to the biota in the estuary. To investigate this four macroinvertebrates, Neotrypaea uncinata (ghostshrimp), Elminius kingii (barnacle), Hemigrapsus crenulatus (shore crab) and Perinereis gualpensis (ragworm) were collected seasonally from three different sites in the Lenga Estuary and one in a reference estuary (Tubul Estuary), and analyzed for Hg and stable isotopes ({delta}{sup 15}N and {delta}{sup 13}C). Mercury concentrations in Lenga sediments ranged from 0.4 {+-} 0.1 to 13 {+-} 3 mg/kg, while those in Tubul sediments ranged from 0.02 {+-} 0.01 to 0.07 {+-} 0.09 mg/kg. Total Hg concentrations of invertebrates were significantly different between estuaries (p < 0.05), but not by species or season for each estuary (p > 0.05). In contrast, organic Hg concentrations were different by species and season with shore crab muscle tissues exhibiting the greatest percent difference. Site-specific relationships demonstrated that total Hg concentrations in ragworm best reflected the total Hg sediment mercury concentrations. Signatures of {delta}{sup 13}C were correlated to the organic Hg % rather than total Hg. This suggests that organic Hg concentrations in these species were related to the carbon sources. -- Highlights: Black-Right-Pointing-Pointer Hg in sediments and biota from Lenga Estuary were elevated compared to nearby estuary. Black-Right-Pointing-Pointer Invertebrates showed interspecific and seasonal differences in terms of organic Hg %. Black-Right-Pointing-Pointer Total Hg levels in the ragworm best reflect Hg sediment gradient in Lenga Estuary. Black-Right-Pointing-Pointer Interspecific variation in {delta}{sup 13}C signatures indicated different feeding modes. Black

  11. {delta}{sup 15}N of seagrass leaves for monitoring anthropogenic nutrient increases in coral reef ecosystems

    Energy Technology Data Exchange (ETDEWEB)

    Yamamuro, M.; Kayanne, H.; Yamano, H

    2003-04-01

    In a coral reef environment, a slight increase in dissolved inorganic nitrogen (DIN;{>=}1.0 {mu}M) can alter the ecosystem via macroalgal blooms. We collected seagrass leaves from the tropical and subtropical Pacific Ocean in five countries and examined the interactions between nutrient concentrations (C, N, P), molar ratios of nutrients, and {delta}{sup 15}N to find a possible indicator of the DIN conditions. Within most sites, the concentrations of nutrients and their molar ratios showed large variations owing to species-specific values. On the other hand, almost identical {delta}{sup 15}N values were found in seagrass leaves of several species at each site. The correlations between {delta}{sup 15}N and nutrient concentrations and between {delta}{sup 15}N and molar ratios of nutrients suggested that nutrient availability did not affect the {delta}{sup 15}N value of seagrass leaves by altering the physiological condition of the plants. Increases in {delta}{sup 15}N of seagrass leaves mostly matched increases in DIN concentrations in the bottom water. We suggest that {delta}{sup 15}N in seagrass leaves can be a good tool to monitor time-integrated decrease/increase of DIN concentrations at a site, both in the water column and the interstitial water.

  12. δ15N value does not reflect fasting in mysticetes.

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    Alex Aguilar

    Full Text Available The finding that tissue δ(15N values increase with protein catabolism has led researchers to apply this value to gauge nutritive condition in vertebrates. However, its application to marine mammals has in most occasions failed. We investigated the relationship between δ(15N values and the fattening/fasting cycle in a model species, the fin whale, a migratory capital breeder that experiences severe seasonal variation in body condition. We analyzed two tissues providing complementary insights: one with isotopic turnover (muscle and one that keeps a permanent record of variations in isotopic values (baleen plates. In both tissues δ(15N values increased with intensive feeding but decreased with fasting, thus contradicting the pattern previously anticipated. The apparent inconsistency during fasting is explained by the fact that a individuals migrate between different isotopic isoscapes, b starvation may not trigger significant negative nitrogen balance, and c excretion drops and elimination of 15N-depleted urine is minimized. Conversely, when intensive feeding is resumed in the northern grounds, protein anabolism and excretion start again, triggering 15N enrichment. It can be concluded that in whales and other mammals that accrue massive depots of lipids as energetic reserves and which have limited access to drinking water, the δ15N value is not affected by fasting and therefore cannot be used as an indication of nutritive condition.

  13. Potential for assessing long-term dynamics in soil nitrogen availability from variations in delta15N of tree rings.

    Science.gov (United States)

    Hart, S C; Classen, A T

    2003-03-01

    Numerous researchers have used the isotopic signatures of C, H, and O in tree rings to provide a long-term record of changes in the physiological status, climate, or water-source use of trees. The frequently limiting element N is also found in tree rings, and variation in its isotopic signature may provide insight into long-term changes in soil N availability of a site. However, research has suggested that N is readily translocated among tree ring of different years; such infidelity between the isotopic compositions of the N taken up from the soil and the N contained in the ring of that growth year would obscure the long-term N isotopic record. We used a 15-year 15N-tracer study to assess the degree of N translocation among tree rings in ponderosa pine (Pinus ponderosa) trees growing in a young, mixed-conifer plantation. We also measured delta13C and delta15N values in unlabeled trees to assess the degree of their covariance in wood tissue, and to explore the potential for a biological linkage between them. We found that the maximum delta15N values in rings from the labeled trees occurred in the ring formed one-year after the 15N was applied to the roots. The delta15N value of rings from labeled trees declined exponentially and bidirectionally from this maximum peak, toward younger and older rings. The unlabeled trees showed considerable interannual variation in the delta15N values of their rings (up to 3 and 5 per thousand), but these values correlated poorly between trees over time and differed by as much as 6 per thousand. Removal of extractives from the wood reduced their delta15N value, but the change was fairly small and consistent among unlabeled trees. The delta13C and delta15N values of tree rings were correlated over time in only one of the unlabeled trees. Across all trees, both delta13C values of tree rings and annual stem wood production were well correlated with annual precipitation, suggesting that soil water balance is an important environmental

  14. A Survey of \\delta18O and \\delta15N Ratios in Ground Water from an Agricultural Community in the San Joaquin Valley, California

    Science.gov (United States)

    Glowacki, S. D.; Suen, C. J.

    2004-12-01

    We studied ground water samples from domestic and monitoring wells in an agricultural community in the eastern side of the San Joaquin Valley, California. The study area is rich in alluvial soils creating an extremely fertile farmland. Livestock farms and agricultural fields are abundant in the area. Fifty-four ground water samples were analyzed for \\delta18O and \\delta15N in dissolved nitrate, in addition to nutrients and major minerals. Nitrate concentration levels in groundwater are elevated and affected by agricultural and other activities. Possible sources of nutrients include: a municipal waste-water treatment facility, a raisin processing plant, a meat processing plant, a turkey farm, diary operations, and agricultural fields. However, except for the turkey farm and a diary, we found no statistical significant contribution of nitrate from the other facilities as compared to the rest of the area. The \\delta18O versus \\delta15N ratios plot of dissolved ground water nitrate shows most samples clustered around an area consistent with soil organic nitrogen. In addition, the rest of the samples show a trend that is indicative of denitrification process. Generally, high \\delta15N values are associated with low nitrate concentrations. The isotopic signal of denitrification is particularly pronounced in samples in the vicinity of the waste water treatment facility, where the highest values of \\delta15N and the lowest nitrate concentrations are observed. However, these samples also have elevated chloride concentrations indicating a waste-water source. These data suggest that the denitrification in the subsurface may have been enhanced by bacteria species introduced by the effluence of the plant. [This study was performed with the collaboration of Steven R Silva of USGS, Menlo Park, and Iris Yamagata and Holly Jo Ferrin of California Department of Water Resources.

  15. Evaluating mercury biomagnification in fish from a tropical marine environment using stable isotopes (delta13C and delta15N).

    Science.gov (United States)

    Al-Reasi, Hassan A; Ababneh, Fuad A; Lean, David R

    2007-08-01

    Concentrations of total mercury (T-Hg) and methylmercury (MeHg) were measured in zooplankton and 13 fish species from a coastal food web of the Gulf of Oman, an arm of the Arabian Sea between Oman and Iran. Stable isotope ratios (delta13C and delta15N) also were determined to track mercury biomagnification. The average concentration of T-Hg in zooplankton was 21 +/- 8.0 ng g(-1) with MeHg accounting 10% of T-Hg. Total mercury levels in fish species ranged from 3.0 ng g(-1) (Sardinella longiceps) to 760 ng g(-1) (Rhizoprionodon acutus) with relatively lower fraction of MeHg (72%) than that found in other studies. The average trophic difference (Deltadelta13C) between zooplankton and planktivorous fish (Selar crumenopthalmus, Rastrelliger kanagurta, and S. longiceps) was higher (3.4 per thousandth) than expected, suggesting that zooplankton may not be the main diet or direct carbon source for these fish species. However, further sampling would be required to compensate for temporal changes in zooplankton and the influence of their lipid content. Trophic position inferred by delta15N and and slopes of the regression equations (log10[T-Hg] = 0.13[delta15N] - 3.57 and log10[MeHg] = 0.14[delta15N] - 3.90) as estimates of biomagnification indicate that biomagnification of T-Hg and MeHg was lower in this tropical ocean compared to what has been observed in arctic and temperate ecosystems and tropical African lakes. The calculated daily intake of methylmercury in the diet of local people through fish consumption was well below the established World Health Organization (WHO) tolerable daily intake threshold for most of the fish species except Euthynnus affinis, Epinephelus epistictus, R. acutus, and Thunnus tonggol, illustrating safe consumption of the commonly consumed fish species.

  16. Effects of growth and change of food on the {delta}{sup 15}N in marine fishes

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    Kasamatsu, Fujio [Marine Ecology Research Inst., Tokyo (Japan); Sato, Rie; Park, Kwang Lai

    1998-06-01

    Information is limited concerning variation of the {delta}{sup 15}N with growth in marine organisms and consequently the effect of growth of marine biota on the {delta}{sup 15}N is not yet well understood. The {delta}{sup 15}N in 26 species of marine fishes taken from Japanese coastal waters together with 4664 stomach contents of these fishes were examined to investigate the effects of food habits and growth on the {delta}{sup 15}N. The mean {delta}{sup 15}N for two species that fed mainly on large-size fishes and six species that fed mainly on small-size fishes were 14.5{+-}1.0per mille and 12.8{+-}0.7per mille, respectively. For five species that fed mainly on decapod crustaceans, two species that fed mainly on zooplankton, and three species that fed mainly on benthos (mainly Polychaeta), the {delta}{sup 15}N were 13.0{+-}0.7, 9.7{+-}0.9, and 12.2{+-}1.2per mille, respectively. The mean {delta}{sup 15}N in the species whose prey were mainly fish or decapod crustaceans was about 3-5per mille higher than the species whose prey was mainly zooplankton. Within the four species that shift their food habits with growth to higher trophic level, the {delta}{sup 15}N significantly increased with growth in one species (Pacific cod), while not significant increase in the {delta}{sup 15}N with growth in the remaining species. (author)

  17. Macroalgal bioindicators (growth, tissue N, delta(15)N) detect nutrient enrichment from shrimp farm effluent entering Opunohu Bay, Moorea, French Polynesia.

    Science.gov (United States)

    Lin, David T; Fong, Peggy

    2008-02-01

    Nutrient enrichment from shrimp aquaculture poses an increasing environmental threat due to the industry's projected rapid growth and unsustainable management practices. Traditional methods to monitor impacts emphasize water quality sampling; however, there are many advantages to bioindicators, especially in developing countries. We investigated the usefulness of three bioindicators -- growth, tissue nitrogen content and nitrogen stable isotope signature (delta(15)N) -- in the tropical red macroalga Acanthophora spicifera. Algae were collected, cultured, and deployed in a spatial array around the outflow from a shrimp farm in Moorea, French Polynesia, to detect nitrogenous wastes. All three parameters were highest adjacent to the shrimp farm indicating nutrient enrichment, and delta(15)N values confirmed the shrimp farm as the dominant nutrient source (5.63-5.96 per thousand). Isotope ratios proved the most sensitive indicator, as delta(15)N signatures were detected at the most distant sites tested, confirming their usefulness in tracing nutrients and mapping the spatial extent of enrichment.

  18. Nutrient Status and δ15N Values in Leaves and Soils: A Cross-Biome Comparison

    Science.gov (United States)

    Mayor, J. R.; Schuur, E. A.; Turner, B. L.; Wright, S. J.

    2011-12-01

    Stable nitrogen (N) isotope ratios (δ15N) are often assumed to provide an integrated measure of multiple nitrogen cycling processes. For instance, shifts in the bioavailability of soil N forms are thought to alter plant δ15N values. Demonstrating this relationship is important as ecosystems undergo anthropogenic disturbances. We evaluated patterns and implied mechanisms of the N cycle using ecosystem δ15N values from 16 plots in boreal black spruce (Picea mariana) forest and lowland wet tropical forest. Fertilizer N and phosphorus (P) was applied annually for five and 11 years prior to measurement of ecosystem δ15N values. Full sun canopy foliage and soil extractable nitrate, ammonium, and dissolved organic N (DON) were sampled in fertilized and control plots and analyzed for δ15N. In boreal forest, N fertilization reduced DON concentrations and caused a depletion of δ15N in foliage and fungal sporocarps. Of four species occurring in all plots in the tropical forest, one (Alseis blackiana) had increased foliar δ15N values following N fertilization, one (Tetragastris panamensis) had increased foliar δ15N values following P fertilization, and one (Oenocarpus mapora) had increased foliar δ15N following N+P fertilization. Surprisingly, soil nitrate in the boreal forest became substantially 15N-enriched under P fertilization, whereas nitrate in the tropical forest soil was enriched only under N or N+P fertilization. Collectively, nitrate enrichment is likely due to enhanced rates of soil denitrification as evidenced by elevated resin extractable soil nitrate concentrations and close correlations between δ15N and δ18O values. On average, foliar δ15N in tropical trees corresponded well with δ15N in soil nitrate in control and P fertilized plots, but was 2-3% more enriched than DON under N and N+P fertilization. In boreal forests, N and N+P fertilization increased foliar N concentration and δ15N values indicating substantial use of applied fertilizer. Taken

  19. Macroalgal bioindicators (growth, tissue N, {delta}{sup 15}N) detect nutrient enrichment from shrimp farm effluent entering Opunohu Bay, Moorea, French Polynesia

    Energy Technology Data Exchange (ETDEWEB)

    Lin, David T. [Department of Zoology, University of Hawaii at Manoa, 2538 McCarthy Mall, Edmondson 152, Honolulu, HI 96822 (United States)], E-mail: david.t.lin@ucla.edu; Fong, Peggy [Department of Ecology and Evolutionary Biology, University of California, Los Angeles, 621 Young Drive South, Los Angeles, CA 90095 (United States)

    2008-02-15

    Nutrient enrichment from shrimp aquaculture poses an increasing environmental threat due to the industry's projected rapid growth and unsustainable management practices. Traditional methods to monitor impacts emphasize water quality sampling; however, there are many advantages to bioindicators, especially in developing countries. We investigated the usefulness of three bioindicators-growth, tissue nitrogen content and nitrogen stable isotope signature ({delta}{sup 15}N)-in the tropical red macroalga Acanthophora spicifera. Algae were collected, cultured, and deployed in a spatial array around the outflow from a shrimp farm in Moorea, French Polynesia, to detect nitrogenous wastes. All three parameters were highest adjacent to the shrimp farm indicating nutrient enrichment, and {delta}{sup 15}N values confirmed the shrimp farm as the dominant nutrient source (5.63-5.96 per mille ). Isotope ratios proved the most sensitive indicator, as {delta}{sup 15}N signatures were detected at the most distant sites tested, confirming their usefulness in tracing nutrients and mapping the spatial extent of enrichment.

  20. An improved method for delta 15N measurements in ice cores

    Directory of Open Access Journals (Sweden)

    M. Leuenberger

    2008-02-01

    Full Text Available The use of isotopic ratios of nitrogen gas (δ15N trapped in ice cores as a paleothermometer to characterise abrupt climate changes is becoming a widespread technique. The versatility of the technique could be enhanced, for instance in quantifying small temperature changes during the last glacial period in Antarctic ice cores, by using high precision methods. In this paper, we outline a method for measuring δ15N to a precision of 0.006permil (1σ, n=9 from replicate ice core samples. The high precision results from removing oxygen, carbon dioxide and water vapour from the air extracted from ice cores. The advantage of the technique is that it does not involve correction for isobaric interference due to CO+ ions. We also highlight the importance of oxygen removal from the sample, and how it influences δ15N measurements. The results show that a small amount of oxygen in the sample can be detrimental to achieving an optimum precision in δ15N measurements of atmospheric nitrogen trapped ice core samples.

  1. Investigations of (Delta)14C, (delta)13C, and (delta)15N in vertebrae of white shark (Carcharodon carcharias) from the eastern North Pacific Ocean

    Energy Technology Data Exchange (ETDEWEB)

    Kerr, L A; Andrews, A H; Cailliet, G M; Brown, T A; Coale, K H

    2006-06-08

    The white shark (Carcharodon carcharias) has a complex life history that is characterized by large scale movements and a highly variable diet. Estimates of age and growth for the white shark from the eastern North Pacific Ocean indicate they have a slow growth rate and a relatively high longevity. Age, growth, and longevity estimates useful for stock assessment and fishery models, however, require some form of validation. By counting vertebral growth band pairs, ages can be estimated, but because not all sharks deposit annual growth bands and many are not easily discernable, it is necessary to validate growth band periodicity with an independent method. Radiocarbon ({sup 14}C) age validation uses the discrete {sup 14}C signal produced from thermonuclear testing in the 1950s and 1960s that is retained in skeletal structures as a time-specific marker. Growth band pairs in vertebrae, estimated as annual and spanning the 1930s to 1990s, were analyzed for {Delta}{sup 14}C and stable carbon and nitrogen isotopes ({delta}{sup 13}C and {delta}{sup 15}N). The aim of this study was to evaluate the utility of {sup 14}C age validation for a wide-ranging species with a complex life history and to use stable isotope measurements in vertebrae as a means of resolving complexity introduced into the {sup 14}C chronology by ontogenetic shifts in diet and habitat. Stable isotopes provided useful trophic position information; however, validation of age estimates was confounded by what may have been some combination of the dietary source of carbon to the vertebrae, large-scale movement patterns, and steep {sup 14}C gradients with depth in the eastern North Pacific Ocean.

  2. Impact of charring on cereal grain characteristics: linking prehistoric manuring practice to <delta>15N signatures in archaeobotanical material

    DEFF Research Database (Denmark)

    Kanstrup, Marie; Thomsen, Ingrid Kaag; Mikkelsen, Peter Hambro

    2012-01-01

    Systematic use of animal manure has been demonstrated to be detectable in the plant δ15N value but evidence of manure affecting isotopic composition is mainly based on studies of fresh plant material. These findings can potentially be applied to archaeobotanical assemblages and thus provide...

  3. Paleoenvironmental implications of taxonomic variation among δ 15 N values of chloropigments

    Science.gov (United States)

    Higgins, Meytal B.; Wolfe-Simon, Felisa; Robinson, Rebecca S.; Qin, Yelun; Saito, Mak A.; Pearson, Ann

    2011-11-01

    Natural variations in the ratios of nitrogen isotopes in biomass reflect variations in nutrient sources utilized for growth. In order to use δ 15N values of chloropigments of photosynthetic organisms to determine the corresponding δ 15N values of biomass - and by extension, surface waters - the isotopic offset between chlorophyll and biomass must be constrained. Here we examine this offset in various geologically-relevant taxa, grown using nutrient sources that may approximate ocean conditions at different times in Earth's history. Phytoplankton in this study include cyanobacteria (diazotrophic and non-diazotrophic), eukaryotic algae (red and green), and anoxygenic photosynthetic bacteria (Proteobacteria), as well as environmental samples from sulfidic lake water. Cultures were grown using N 2, NO 3-, and NH 4+ as nitrogen sources, and were examined under different light regimes and growth conditions. We find surprisingly high variability in the isotopic difference (δ 15N biomass - δ 15N chloropigment) for prokaryotes, with average values for species ranging from -12.2‰ to +11.7‰. We define this difference as ɛpor, a term that encompasses diagenetic porphyrins and chlorins, as well as chlorophyll. Negative values of ɛpor reflect chloropigments that are 15N-enriched relative to biomass. Notably, this enrichment appears to occur only in cyanobacteria. The average value of ɛpor for freshwater cyanobacterial species is -9.8 ± 1.8‰, while for marine cyanobacteria it is -0.9 ± 1.3‰. These isotopic effects group environmentally but not phylogenetically, e.g., ɛpor values for freshwater Chroococcales resemble those of freshwater Nostocales but differ from those of marine Chroococcales. Our measured values of ɛpor for eukaryotic algae (range = 4.7-8.7‰) are similar to previous reports for pure cultures. For all taxa studied, values of ɛpor do not depend on the type of nitrogen substrate used for growth. The observed environmental control of

  4. Determination of the delta(15N/14N)of Ammonium (NH4+) in Water: RSIL Lab Code 2898

    Science.gov (United States)

    Hannon, Janet E.; Böhlke, John Karl

    2008-01-01

    The purpose of the technique described by Reston Stable Isotope Laboratory (RSIL) lab code 2898 is to determine the N isotopic composition, delta(15N/14N), abbreviated as d15N, of ammonium (NH4+) in water (freshwater and saline water). The procedure involves converting dissolved NH4+ into NH3 gas by raising the pH of the sample to above 9 with MgO and subsequently trapping the gas quantitatively as (NH4)2SO4 on a glass fiber (GF) filter. The GF filter is saturated with NaHSO4 and pressure sealed between two gas-permeable polypropylene filters. The GF filter 'sandwich' floats on the surface of the water sample in a closed bottle. NH3 diffuses from the water through the polypropylene filter and reacts with NaHSO4, forming (NH4)2SO4 on the GF filter. The GF filter containing (NH4)2SO4 is dried and then combusted with a Carlo Erba NC 2500 elemental analyzer (EA), which is used to convert total nitrogen in a solid sample into N2 gas. The EA is connected to a continuous-flow isotope-ratio mass spectrometer (CF-IRMS), which determines the relative difference in ratios of the amounts of the stable isotopes of nitrogen (15N and 14N) of the product N2 gas and a reference N2 gas. The filters containing the samples are compressed in tin capsules and loaded into a Costech Zero-Blank Autosampler on the EA. Under computer control, samples then are dropped into a heated reaction tube that contains an oxidant, where combustion takes place in a He atmosphere containing an excess of O2 gas. To remove S-O gases produced from the NaHSO4, a plug of Ag-coated Cu wool is inserted at the bottom of the reaction tube. Combustion products are transported by a He carrier through a reduction furnace to remove excess O2, toconvert all nitrogen oxides to N2, and to remove any remaining S-O gases. The gases then pass through a drying tube to remove water. The gas-phase products, mainly N2 and a small amount of background CO2, are separated by a gas chromatograph (GC). The gas is then introduced

  5. Paleoenvironmental implications of taxonomic variation among δ15N values of chloropigments

    Science.gov (United States)

    Higgins, Meytal B.; Wolfe-Simon, Felisa; Robinson, Rebecca S.; Qin, Yelun; Saito, Mark A.; Pearson, Ann

    2011-01-01

    Natural variations in the ratios of nitrogen isotopes in biomass reflect variations in nutrient sources utilized for growth. In order to use δ15N values of chloropigments of photosynthetic organisms to determine the corresponding δ15N values of biomass – and by extension, surface waters – the isotopic offset between chlorophyll and biomass must be constrained. Here we examine this offset in various geologically-relevant taxa, grown using nutrient sources that may approximate ocean conditions at different times in Earth’s history. Phytoplankton in this study include cyanobacteria (diazotrophic and non-diazotrophic), eukaryotic algae (red and green), and anoxygenic photosynthetic bacteria (Proteobacteria), as well as environmental samples from sulfidic lake water. Cultures were grown using N2, NO3−, and NH4+ as nitrogen sources, and were examined under different light regimes and growth conditions. We find surprisingly high variability in the isotopic difference (δ15Nbiomass − δ15Nchloropigment) for prokaryotes, with average values for species ranging from −12.2‰ to +11.7‰. We define this difference as εpor, a term that encompasses diagenetic porphyrins and chlorins, as well as chlorophyll. Negative values of εpor reflect chloropigments that are 15N-enriched relative to biomass. Notably, this enrichment appears to occur only in cyanobacteria. The average value of εpor for freshwater cyanobacterial species is −9.8 ± 1.8‰, while for marine cyanobacteria it is −0.9 ± 1.3‰. These isotopic effects group environmentally but not phylogenetically, e.g., εpor values for freshwater Chroococcales resemble those of freshwater Nostocales but differ from those of marine Chroococcales. Our measured values of εpor for eukaryotic algae (range = 4.7–8.7‰) are similar to previous reports for pure cultures. For all taxa studied, values of εpor do not depend on the type of nitrogen substrate used for growth. The observed

  6. Sensitive measurement of NH4+ 15N/14N (delta 15NH4+) at natural abundance levels in fresh and saltwaters.

    Science.gov (United States)

    Zhang, Lin; Altabet, Mark A; Wu, Taixing; Hadas, Ora

    2007-07-15

    We report a new method for determining the 15N/14N of NH4+ at natural abundance level in both freshwater and seawater. NH4+ is first quantitatively oxidized to NO2- by hypobromite (BrO-) at pH approximately 12. After the addition of sodium arsenite to consume excess BrO-, yield is verified by colorimetric NO2- determination. NO2- is further reduced to N2O using a 1:1 sodium azide and acetic acid buffer solution using previously established procedures. The product N2O is then analyzed for isotopic composition using a continuous flow purge and cryogenic trap system coupled to an isotope ratio mass spectrometer. Reliable delta 15N values (standard deviation is 0.3 per thousand or better) are obtained over an NH4+ concentration range of 0.5-10 microM using 20 mL volumes of either freshwater or seawater samples. Higher concentration samples are readily diluted to lower concentration. Preexisting NO2- is removed by treatment with sulfanilic acid. There is no interference from any of the nitrogen-containing compounds tested except short-chain aliphatic amino acids (i.e., glycine) which typically are present at very low environmental concentrations. As compared to published methods, our approach is more robust, readily applicable at low concentrations and small sample volumes, and requires less time for preparation and analysis.

  7. Simultaneous delta15N, delta13C and delta34S measurements of low-biomass samples using a technically advanced high sensitivity elemental analyzer connected to an isotope ratio mass spectrometer.

    Science.gov (United States)

    Hansen, T; Burmeister, A; Sommer, U

    2009-11-01

    Conventional simultaneous CNS stable isotope abundance measurements of solid samples usually require high sample amounts, up to 1 mg carbon, to achieve exact analytical results. This rarely used application is often impaired by high C:S element ratios when organic samples are analyzed and problems such as incomplete conversion into sulphur dioxide occur during analysis. We introduce, as a technical innovation, a high sensitivity elemental analyzer coupled to a conventional isotope ratio mass spectrometer, with which CNS-stable isotope ratios can be determined simultaneously in samples with low carbon content (<40 microg C corresponding to approximately 100 microg dry weight). The system includes downsized reactors, a temperature program-controlled gas chromatography (GC) column and a cryogenic trap to collect small amounts of sulphur dioxide. This modified application allows for highly sensitive measurements in a fully automated operation with standard deviations better than +/-0.47 per thousand for delta15N and delta34S and +/-0.12 per thousand for delta13C (n = 127). Samples collected from one sampling site in a Baltic fjord within a short time period were measured with the new system to get a first impression of triple stable isotope signatures. The results confirm the potential of using delta34S as a stable isotope tracer in combination with delta15N and delta13C measurements to improve discrimination of food sources in aquatic food webs.

  8. Macroalgae δ15N values in well-mixed estuaries: Indicator of anthropogenic nitrogen input or macroalgae metabolism?

    Science.gov (United States)

    Raimonet, Mélanie; Guillou, Gaël; Mornet, Françoise; Richard, Pierre

    2013-03-01

    Although nitrogen stable isotope ratio (δ15N) in macroalgae is widely used as a bioindicator of anthropogenic nitrogen inputs to the coastal zone, recent studies suggest the possible role of macroalgae metabolism in δ15N variability. Simultaneous determinations of δ15N of dissolved inorganic nitrogen (DIN) along the land-sea continuum, inter-species variability of δ15N and its sensitivity to environmental factors are necessary to confirm the efficiency of macroalgae δ15N in monitoring nitrogen origin in mixed-use watersheds. In this study, δ15N of annual and perennial macroalgae (Ulva sp., Enteromorpha sp., Fucus vesiculosus and Fucus serratus) are compared to δ15N-DIN along the Charente Estuary, after characterizing δ15N of the three main DIN sources (i.e. cultivated area, pasture, sewage treatment plant outlet). During late winter and spring, when human activities produce high DIN inputs, DIN sources exhibit distinct δ15N signals in nitrate (NO) and ammonium (NH): cultivated area (+6.5 ± 0.6‰ and +9.0 ± 11.0‰), pasture (+9.2 ± 1.8‰ and +12.4‰) and sewage treatment plant discharge (+16.9 ± 8.7‰ and +25.4 ± 5.9‰). While sources show distinct δN- in this multiple source catchment, the overall mixture of NO sources - generally >95% DIN - leads to low variations of δN-NO at the mouth of the estuary (+7.7 to +8.4‰). Even if estuarine δN-NO values are not significantly different from pristine continental and oceanic site (+7.3‰ and +7.4‰), macroalgae δ15N values are generally higher at the mouth of the estuary. This highlights high anthropogenic DIN inputs in the estuary, and enhanced contribution of 15N-depleted NH in oceanic waters. Although seasonal variations in δN-NO are low, the same temporal trends in macroalgae δ15N values at estuarine and oceanic sites, and inter-species differences in δ15N values, suggest that macroalgae δ15N values might be modified by the metabolic response of macroalgae to environmental parameters (e

  9. δ15N Values in Crassostrea virginica Shells Provides Early Direct Evidence for Nitrogen Loading to Chesapeake Bay

    Science.gov (United States)

    Black, H. D.; Andrus, C. F. T.; Lambert, W. J.; Rick, T. C.; Gillikin, D. P.

    2017-01-01

    Crassostrea virginica is one of the most common estuarine bivalves in the United States’ east coast and is frequently found in archaeological sites and sub-fossil deposits. Although there have been several sclerochronological studies on stable carbon and oxygen isotopes in the shells of this species, less is known about δ15N values within their shells, which could be a useful paleoenvironmental proxy to assess estuarine nitrogen dynamics. Modern C. virginica samples were collected in Chesapeake Bay for comparison with archaeological shells from nearby sites ranging in age from ~100 to 3,200 years old. Left valves were sampled by milling the hinge area and the resulting powder was analyzed for %N and δ15N values. Comparison of δ15N values between C. virginica shells shows relatively constant values from ~1250 BC to ~1800 AD. After ~1800 AD, there are rapid increases in 15N enrichment in the shells, which continue to increase in value up to the modern shell values. The increase in δ15N values is evidence of early anthropogenic impact in Chesapeake Bay. These results corroborate the observation that coastal nitrogen pollution occurred earlier than the 19th century and support the use of oyster shell δ15N values as a useful environmental proxy. PMID:28281649

  10. Atmospheric transport of urban-derived NH(x): Evidence from nitrogen concentration and delta(15)N in epilithic mosses at Guiyang, SW China.

    Science.gov (United States)

    Liu, Xue-Yan; Xiao, Hua-Yun; Liu, Cong-Qiang; Li, You-Yi; Xiao, Hong-Wei

    2008-12-01

    Nitrogen concentration and delta15N in 175 epilithic moss samples were investigated along four directions from urban to rural sites in Guiyang, SW China. The spatial variations of moss N concentration and delta15N revealed that atmospheric N deposition is dominated by NHx-N from two major sources (urban sewage NH3 and agricultural NH3), the deposition of urban-derived NHx followed a point source pattern characterized by an exponential decline with distance from the urban center, while the agricultural-derived NHx was shown to be a non-point source. The relationship between moss N concentration and distance (y=1.5e(-0.13x)+1.26) indicated that the maximum transporting distance of urban-derived NHx averaged 41 km from the urban center, and it could be determined from the relationship between moss delta(15)N and distance [y=2.54ln(x)-12.227] that urban-derived NHx was proportionally lower than agricultural-derived NHx in N deposition at sites beyond 17.2 km from the urban center. Consequently, the variation of urban-derived NHx with distance from the urban center could be modeled as y=56.272e(-0.116x)-0.481 in the Guiyang area.

  11. Variation in hair δ13C and δ15N values in long-tailed macaques (Macaca fascicularis) from Singapore

    Science.gov (United States)

    Schillaci, Michael A.; Castellini, J. Margaret; Stricker, Craig A.; Jones-Engel, Lisa; Lee, Benjamin P.Y.-H.

    2014-01-01

    Much of the primatology literature on stable isotope ratios of carbon (δ13C) and nitrogen (δ15N) has focused on African and New World species, with comparatively little research published on Asian primates. Here we present hair δ13C and δ15N isotope values for a sample of 33 long-tailed macaques from Singapore. We evaluate the suggestion by a previous researcher that forest degradation and biodiversity loss in Singapore have led to a decline in macaque trophic level. The results of our analysis indicated significant spatial variability in δ13C but not δ15N. The range of variation in δ13C was consistent with a diet based on C3 resources, with one group exhibiting low values consistent with a closed canopy environment. Relative to other macaque species from Europe and Asia, the macaques from Singapore exhibited a low mean δ13C value but mid-range mean δ15N value. Previous research suggesting a decline in macaque trophic level is not supported by the results of our study.

  12. Sediment features, macrozoobenthic assemblages and trophic relationships ({delta}{sup 13}C and {delta}{sup 15}N analysis) following a dystrophic event with anoxia and sulphide development in the Santa Giusta lagoon (western Sardinia, Italy)

    Energy Technology Data Exchange (ETDEWEB)

    Magni, P. [CNR-IAMC National Research Council - Institute for Coastal Marine Environment c/o IMC - International Marine Centre, Loc. Sa Mardini, Torregrande, 09072 Oristano (Italy); IMC - International Marine Centre, Loc. Sa Mardini, Torregrande, 09072 Oristano (Italy)], E-mail: paolo.magni@iamc.cnr.it; Rajagopal, S. [Department of Animal Ecology and Ecophysiology, Institute for Water and Wetland Research, Radboud University Nijmegen, Toernooiveld, 6525 ED Nijmegen (Netherlands); Velde, G. van der [Department of Animal Ecology and Ecophysiology, Institute for Water and Wetland Research, Radboud University Nijmegen, Toernooiveld, 6525 ED Nijmegen (Netherlands); National Museum of Natural History Naturalis, P.O. Box 9517, 2300 RA Leiden (Netherlands); Fenzi, G. [IMC - International Marine Centre, Loc. Sa Mardini, Torregrande, 09072 Oristano (Italy); Kassenberg, J. [Department of Animal Ecology and Ecophysiology, Institute for Water and Wetland Research, Radboud University Nijmegen, Toernooiveld, 6525 ED Nijmegen (Netherlands); Vizzini, S.; Mazzola, A. [Dipartimento di Biologia Animale, Universita di Palermo, via Archirafi 18, 90123 Palermo (Italy); Giordani, G. [Dipartimento di Scienze Ambientali, Universita di Parma, Via Usberti 33/A, 43100 Parma (Italy)

    2008-07-01

    Macrozoobenthic assemblages and stable carbon ({delta}{sup 13}C) and nitrogen ({delta}{sup 15}N) isotope values of various primary producers (macroalgae and angiosperms) and consumers (macroinvertebrate filter/suspension feeders, deposit feeders, detritivores/omnivores and carnivores and fishes) were studied in the Santa Giusta lagoon (Sardinia, Italy) before (spring) and after (autumn) a dystrophic event which occurred in the summer of 2004. A few days after the dystrophy, the physico-chemical characteristics of sediments and macrozoobenthic assemblages were also investigated. In the latter occasion, high total organic carbon (3.9%) and organic matter (15.9%) contents of surface sediments went together with peaks in acid-volatile sulphide concentrations. Certain immediate effects were quite extreme, such as the drastic reduction in macrozoobenthos and the massive fish kill in August 2004. Among the macrozoobenthos, there were few individuals of chironomid larvae and Capitella cf. capitata left. However, by October, chironomid larvae were numerous, indicating a lack of predators (e.g. fish) and competitors. In addition, some bivalve species and polychaetes which were absent, or present in small numbers before the event, became relatively numerous. The results are discussed based on a knowledge of the sulphide tolerance of these species. Stable isotope analysis clearly showed that the basal level of the food web for most consumers consisted mainly of macroalgae and sedimentary organic matter, and that the values before and after the dystrophic event were not significantly different from one another. This indicates that the relations among different trophic levels were quickly restored following the dystrophic event.

  13. Individual protein balance strongly influences δ15N and δ13C values in Nile tilapia, Oreochromis niloticus

    Science.gov (United States)

    Gaye-Siessegger, Julia; Focken, Ulfert; Abel, Hansjörg; Becker, Klaus

    Although stable isotope ratios in animals have often been used as indicators of the trophic level and for the back-calculation of diets, few experiments have been done under standardized laboratory conditions to investigate factors influencing δ15N and δ13C values. An experiment using Nile tilapia [Oreochromis niloticus (L.)] was therefore carried out to test the effect of different dietary protein contents (35.4, 42.3, and 50.9%) on δ15N and δ13C values of the whole tilapia. The fish were fed the isoenergetic and isolipidic semi-synthetic diets at a relatively low level. δ15N and δ13C values of the lipid-free body did not differ between the fish fed the diets with different protein contents, but the trophic shift for N and C isotopes decreased with increasing protein accretion in the individual fish, for N from 6.5‰ to 4‰ and for C in the lipid-free body from 4‰ to 2.5‰. This is the first study showing the strong influence of the individual protein balance to the degree to which the isotopic signature of dietary protein was modified in tissue protein of fish. The extrapolation of the trophic level or the reconstruction of the diet of an animal from stable isotope ratios without knowledge of the individual physiological condition and the feeding rate may lead to erroneous results.

  14. Coupling tree-ring delta13C and delta15N to test the effect of fertilization on mature Douglas-fir (Pseudotsuga menziesii var. glauca) stands across the Interior northwest, USA.

    Science.gov (United States)

    Balster, Nick J; Marshall, John D; Clayton, Murray

    2009-12-01

    Nitrogen (N) fertilization causes long-term increases in biomass production in many N-limited forests around the world, but the mechanistic basis underlying the increase is often unclear. One possibility, especially in summer-dry climates, is that N fertilization increases the efficiency with which a finite water supply is consumed to support photosynthesis. This increase is achieved by a reduction in the canopy-integrated concentration of internal CO(2) and thus discrimination against (13)C. We used stable isotopes of carbon (delta(13)C) in tree rings to experimentally test the physiological impact of N fertilization on mature Douglas-fir (Pseudotsuga menziesii Franco var. glauca) stands across the geographic extent of the Intermountain West, USA. The concentration and the stable isotopes of N (delta(15)N) in tree rings were also used to assess the presence and activity of fertilizer N. We hypothesized that N fertilization would (i) increase delta(15)N and N concentration of stemwood relative to non-fertilized stands and (ii) increase stemwood delta(13)C as photosynthetic gas exchange responded to the additional N. This experiment included two rates of urea addition, 178 kg ha(-1) (low) and 357 kg ha(-1) (high), which were applied twice over a 6-year interval bracketed by the 18 years of wood production measured in this study. Foliar N concentrations measured the year after each fertilization treatment suggest that the fertilizer N had been assimilated by the trees (P fertilization significantly enriched stemwood delta(15)N by 1.3 per thousand at the low fertilization rate and by 2.4 per thousand at the high rate (P fertilizer on delta(13)C of the annual rings (P = 0.76). These data lead us to suggest that alternative mechanisms underlie the growth response to fertilizer, i.e., increase in canopy area and shifts in biomass allocation.

  15. Unusual patterns in 15N blood values after a diet switch in red knot shorebirds

    NARCIS (Netherlands)

    Dietz, M.W.; Piersma, T.; Dekinga, A.; Korthals, H.; Klaassen, M.

    2013-01-01

    When a diet switch results in a change in dietary isotopic values, isotope ratios of the consumer's tissues will change until a new equilibrium is reached. This change is generally best described by an exponential decay curve. Indeed, after a diet switch in captive red knot shorebirds (Calidris

  16. Unusual patterns in 15N blood values after a diet switch in red knot shorebirds

    NARCIS (Netherlands)

    Dietz, M.W.; Piersma, T.; Dekinga, A.; Korthals, H.; Klaassen, M.

    2013-01-01

    When a diet switch results in a change in dietary isotopic values, isotope ratios of the consumer's tissues will change until a new equilibrium is reached. This change is generally best described by an exponential decay curve. Indeed, after a diet switch in captive red knot shorebirds (Calidris canu

  17. Spatial variations in δ13C and δ15N values of primary consumers in a coastal lagoon

    Science.gov (United States)

    Como, S.; Magni, P.; Van Der Velde, G.; Blok, F. S.; Van De Steeg, M. F. M.

    2012-12-01

    The analysis of the contribution of a food source to a consumer's diet or the trophic position of a consumer is highly sensitive to the variability of the isotopic values used as input data. However, little is known in coastal lagoons about the spatial variations in the isotopic values of primary consumers considered 'end members' in the isotope mixing models for quantifying the diet of secondary consumers or as a baseline for estimating the trophic position of consumers higher up in the food web. We studied the spatial variations in the δ13C and δ15N values of primary consumers and sedimentary organic matter (SOM) within a selected area of the Cabras lagoon (Sardinia, Italy). Our aim was to assess how much of the spatial variation in isotopic values of primary consumers was due to the spatial variability between sites and how much was due to differences in short distances from the shore. Samples were collected at four stations (50-100 m apart) selected randomly at two sites (1.5-2 km apart) chosen randomly at two distances from the shore (i.e. in proximity of the shore -Nearshore - and about 200 m away from the shore -Offshore). The sampling was repeated in March, May and August 2006 using new sites at the two chosen distances from the shore on each date. The isotopic values of size-fractionated seston and macrophytes were also analyzed as a complementary characterization of the study area. While δ15N did not show any spatial variations, the δ13C values of deposit feeders, Alitta (=Neanthes) succinea, Lekanesphaera hookeri, Hydrobia acuta and Gammarus aequicauda, were more depleted Offshore than Nearshore. For these species, there were significant effects of distance or distance × dates in the mean δ13C values, irrespective of the intrinsic variation between sites. SOM showed similar spatial variations in δ13C values, with Nearshore-Offshore differences up to 6‰. This indicates that the spatial isotopic changes are transferred from the food sources to the

  18. Macroalgae δ 15 N values in well-mixed estuaries: indicator of anthropogenic nitrogen input or macroalgae metabolism?

    OpenAIRE

    Raimonet, Mélanie; Guillou, Gaël; Mornet, Françoise; Richard, Pierre

    2013-01-01

    International audience; Although nitrogen stable isotope ratio (d15N) in macroalgae is widely used as a bioindicator of anthropogenic nitrogen inputs to the coastal zone, recent studies suggest the possible role of macroalgae metabolism in d15N variability. Simultaneous determinations of d15N of dissolved inorganic nitrogen(DIN) along the landesea continuum, inter-species variability of d15N and its sensitivity to environmental factors are necessary to confirm the efficiency of macroalgae d15...

  19. Human baby hair amino acid natural abundance 15N-isotope values are not related to the 15N-isotope values of amino acids in mother's breast milk protein.

    Science.gov (United States)

    Romek, Katarzyna M; Julien, Maxime; Frasquet-Darrieux, Marine; Tea, Illa; Antheaume, Ingrid; Hankard, Régis; Robins, Richard J

    2013-12-01

    Since exclusively breast-suckled infants obtain their nutrient only from their mother's milk, it might be anticipated that a correlation will exist between the (15)N/(14)N isotope ratios of amino acids of protein of young infants and those supplied by their mother. The work presented here aimed to determine whether amino nitrogen transfer from human milk to infant hair protein synthesized within the first month of life conserves the maternal isotopic signature or whether post-ingestion fractionation dominates the nitrogen isotope spectrum. The study was conducted at 1 month post-birth on 100 mother-infant pairs. Isotope ratios (15)N/(14)N and (13)C/(12)C were measured using isotope ratio measurement by Mass Spectrometry (irm-MS) for whole maternal milk, and infant hair and (15)N/(14)N ratios were also measured by GC-irm-MS for the N-pivaloyl-O-isopropyl esters of amino acids obtained from the hydrolysis of milk and hair proteins. The δ(15)N and δ(13)C (‰) were found to be significantly higher in infant hair than in breast milk (δ(15)N, P amino acids in infant hair was also significantly higher than that in maternal milk (P < 0.001). By calculation, the observed shift in isotope ratio was shown not to be accounted for by the amino acid composition of hair and milk proteins, indicating that it is not simply due to differences in the composition in the proteins present. Rather, it would appear that each pool-mother and infant-turns over independently, and that fractionation in infant N-metabolism even in the first month of life dominates over the nutrient N-content.

  20. Non-lethal approach identifies variability of δ15N values in the fin rays of Atlantic Goliath Grouper, Epinephelus itajara

    Directory of Open Access Journals (Sweden)

    Orian E. Tzadik

    2015-06-01

    Full Text Available The Atlantic Goliath Grouper, Epinephelus itajara, is critically endangered throughout its range but has begun to show initial signs of recovery in Florida state waters. As the population continues to rebound, researchers face a pressing need to fill the knowledge gaps about this iconic species. Here, we examined the δ15N isotopic records in fin rays collected from Atlantic Goliath Grouper, and related changes of isotopic ratios over time to life history characteristics. Fin-ray analysis was used as a non-lethal technique to sample individuals from two locations at similar latitudes from the west and east coasts of Florida, USA. δ15N data were acquired by mechanically separating the annuli of each fin ray and then analyzing the material in an Irradiance Elemental Analyzer Mass Spectrometer. The δ15N values were consistent among individuals within populations from each coast of Florida, and mirrored the expected changes over the lives of the fish. Overall, differences were found between δ15N values at juvenile life history phases versus adult phases, but the patterns associated with these differences were unique to each coastal group. We demonstrated, for the first time, that δ15N values from fin rays can be used to assess the life histories of Atlantic Goliath Grouper. The non-lethal strategies outlined here can be used to acquire information essential to the management of species of concern, such as those that are threatened or endangered.

  1. Non-lethal approach identifies variability of δ15N values in the fin rays of Atlantic Goliath Grouper, Epinephelus itajara

    Science.gov (United States)

    Goddard, Ethan A.; Hollander, David J.; Koenig, Christopher C.; Stallings, Christopher D.

    2015-01-01

    The Atlantic Goliath Grouper, Epinephelus itajara, is critically endangered throughout its range but has begun to show initial signs of recovery in Florida state waters. As the population continues to rebound, researchers face a pressing need to fill the knowledge gaps about this iconic species. Here, we examined the δ15N isotopic records in fin rays collected from Atlantic Goliath Grouper, and related changes of isotopic ratios over time to life history characteristics. Fin-ray analysis was used as a non-lethal technique to sample individuals from two locations at similar latitudes from the west and east coasts of Florida, USA. δ15N data were acquired by mechanically separating the annuli of each fin ray and then analyzing the material in an Irradiance Elemental Analyzer Mass Spectrometer. The δ15N values were consistent among individuals within populations from each coast of Florida, and mirrored the expected changes over the lives of the fish. Overall, differences were found between δ15N values at juvenile life history phases versus adult phases, but the patterns associated with these differences were unique to each coastal group. We demonstrated, for the first time, that δ15N values from fin rays can be used to assess the life histories of Atlantic Goliath Grouper. The non-lethal strategies outlined here can be used to acquire information essential to the management of species of concern, such as those that are threatened or endangered. PMID:26082864

  2. Effects of lipid and urea extraction on δ15N values of deep-sea sharks and hagfish: Can mathematical correction factors be generated?

    Science.gov (United States)

    Churchill, Diana A.; Heithaus, Michael R.; Dean Grubbs, R.

    2015-05-01

    Stable isotope analysis is broadly employed to investigate diverse ecological questions. In order to make appropriate comparisons among multiple taxa, however, it is necessary to standardize values to account for interspecific differences in factors that affect isotopic ratios. For example, varying concentrations of soluble nitrogen compounds, such as urea or trimethylamine oxide, can affect the analysis and interpretation of δ15N values of sharks or hagfish. The goal of this study was to assess the effects of a standard chloroform/methanol extraction on the stable isotope values of muscle tissue obtained from 10 species of sharks and three species of hagfish collected from poorly-known deep-water (>200 m) communities. We detected significant differences in δ15N, %N, and C:N values as a result of extractions in 8 of 10 shark and all three hagfish species. We observed increased δ15N values, but shifts in %N and C:N values were not unidirectional. Mathematical normalizations for δ15N values were successfully created for four shark and two hagfish species. However, they were not successful for two shark species. Therefore, performing extractions of all samples is recommended.

  3. Is delta sup(15)N of sedimentary organic matter a good proxy for paleodenitrification in coastal waters of the eastern Arabian Sea?

    Digital Repository Service at National Institute of Oceanography (India)

    Agnihotri, R.; Naqvi, S.W.A.; Kurian, S.; Altabet, M.A.; Bratton, J.F.

    on the western continental shelf off Goa, the observed contrasting behavior (decreasing trend; Plate 1) of sedimentary d 15 N raises important questions con- cerning regional N isotope systematics. 4. SEDIMENTARY d 15 N RECORDS OF PERU-CHILE MARGIN... that this record exhibits two distinct trends of variability during the last 250 years: (1) Intensifi- cation of interdecadal variability of southerly winds along the arid coast of northern Chile/southern Peru since the 19th century, especially from 1820 to 1878...

  4. A cross-shelf gradient in δ15N stable isotope values of krill and pollock indicates seabird foraging patterns in the Bering Sea

    Science.gov (United States)

    Jones, Nathan M.; Hoover, Brian A.; Heppell, Scott A.; Kuletz, Kathy J.

    2014-11-01

    Concurrent measurements of predator and prey δ15N isotope values demonstrated that a cross-shelf isotopic gradient can propagate through a marine food web from forage species to top-tier predators and indicate foraging areas at a scale of tens of kilometers. We measured δ13C and δ15N in muscle tissues of thick-billed murres (Uria lomvia) and black-legged kittiwakes (Rissa tridactyla), and in whole body tissues of walleye pollock (Gadus chalcogrammus) and krill (Thysanoessa spp), sampled across the continental shelf break in the Bering Sea in 2008 and in 2009. We found significant basin-shelf differences at fine scales (structure of a basin-shelf δ15Nitrogen gradient in the central and southern Bering Sea, and used it to contrast foraging patterns of thick-billed murres and kittiwakes on the open ocean. Seabird muscle δ15N values were compared to baselines created from measurements in krill and pollock tissues sampled concurrently throughout the study area. Krill, pollock, and murre tissues from northern, shallow, shelf habitat (200 m) to the south and west. Krill δ15N baseline values predicted 35-42% of the variability in murre tissue values. Patterns between kittiwakes and prey were less coherent. The persistence of strong spatial autocorrelation among sample values, and a congruence of geospatial patterns in δ15N among murre and prey tissues, suggest that murres forage repeatedly in specific areas. Murre isotope values showed distinct geospatial stratification, coincident with the spatial distribution of three colonies: St. Paul, St. George, and Bogoslof. This suggests some degree of foraging habitat partitioning among colonies.

  5. Symbiotic nitrogen fixation in an arid ecosystem measured by sup 15 N natural abundance

    Energy Technology Data Exchange (ETDEWEB)

    Johnson, G.V. (Univ. of New Mexico, Albuquerque (USA))

    1990-05-01

    Plants dependent on nitrogen fixation have an {sup 15}N abundance similar to the atmosphere, while non-nitrogen fixing plants usually are enriched in {sup 15}N and are similar to soil nitrogen values. The natural abundance of {sup 15}N in leaf tissues and soils was determined to evaluate symbiotic nitrogen fixation by several legumes and actinorhizal species in the Sevilleta Long-term Ecological Research area in central New Mexico. Comparison of {delta}{sup 15}N values for the legume Prosopis glandulosa (mesquite) to adjacent Atriplex canascens (fourwing saltbush) indicated that P. glandulosa obtained 66% of its nitrogen by fixation. The legume Hoffmanseggia jamesii was found to be utilizing soil nitrogen. The {delta}{sup 15}N values for the actinorhizal plants, Elaeagnus angustifolia and Cercocarpus montanus, while below values for soil nitrogen, did not differ from associated non-fixing plants.

  6. Nature and sources of suspended particulate organic matter in a tropical estuary during the monsoon and pre-monsoon: Insights from stable isotopes (delta 13C POC, delta 15 N TPN) and carbohydrate signature compounds

    Digital Repository Service at National Institute of Oceanography (India)

    Khodse, V.B.; Bhosle, N.B.

    sup(15)N sub(TPN), particulate carbohydrates (PCHO), particulate uronic acid (PUA), and particulate neutral carbohydrate (PNCHO) concentration and composition. POC and PCHO concentrations were influenced by cell numbers of bacteria and phytoplankton...

  7. Selection of effective macroalgal species and tracing nitrogen sources on the different part of Yantai coast, China indicated by macroalgal δ{sup 15}N values

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Yujue [Key Laboratory of Coastal Environmental Processes and Ecological Remediation, Yantai Institute of Coastal Zone Research, Chinese Academy of Sciences, Yantai, Shandong 264003 (China); Liu, Dongyan, E-mail: dyliu@yic.ac.cn [Key Laboratory of Coastal Environmental Processes and Ecological Remediation, Yantai Institute of Coastal Zone Research, Chinese Academy of Sciences, Yantai, Shandong 264003 (China); Richard, Pierre [Littoral, Environnement et Sociétés, UMR 7266 CNRS-Université de La Rochelle, 2 rue Olympe de Gouges, 17000 La Rochelle (France); Di, Baoping [Key Laboratory of Coastal Environmental Processes and Ecological Remediation, Yantai Institute of Coastal Zone Research, Chinese Academy of Sciences, Yantai, Shandong 264003 (China)

    2016-01-15

    To determine the dominant nitrogen sources and select effective macroalgal species for monitoring eutrophication along the Yantai coast, the total carbon (TOC), total nitrogen (TN) and nitrogen stable isotope ratio (δ{sup 15}N) in macroalgal tissue were analyzed in conjunction with environmental variables in seawater along the Yantai coastline. The ranges of macroalgal tissue δ{sup 15}N values together with dissolved inorganic nitrogen (DIN) composition indicated that except for the atmospheric deposition, there were three dominant types of nitrogen sources along the Yantai coast, with the agricultural fertilizer usage and factorial wastewater input at the S1 (Zhifu Island coast), the sewage discharge at S2 (the Moon Bay coast), the sewage discharge together with aquaculture impacts at S3 (Fisherman Wharf coast) and S4 (the Horse Island coast). Macroalgal growth were not limited by DIN but limited by P at S2, S3 and S4. Macroalgal species suitable or not for DIN source tracing along the Yantai coast were discussed. For sites with low DIN concentration, many species of three phyla could be used for DIN sources tracing with Laurencia okamurai, Gloiopeltis furcata and Ulva pertusa being ideal species. For site with high DIN concentration, however, species of Rhodophyta were not suitable and only Scytosiphon lomentaria and Monostroma nitidium were chosen. - Highlights: • Yantai coast was affected by three types of DIN sources. • Macroalgal species suitable or not for DIN source tracing were suggested; • TN and δ{sup 15}N were affected by nutrient concentrations and the metabolic factors. • P instead of N limited the tissue N uptake in low nutrient concentration sites.

  8. Preservation in 70% ethanol solution does not affect δ13C and δ15N values of reindeer blood samples – relevance for stable isotope studies of diet

    Directory of Open Access Journals (Sweden)

    Duncan J. Halley

    2008-04-01

    Full Text Available We compared duplicate samples of whole blood samples from 18 reindeer that were preserved either by immediate freezing or by immersion in 70 % ethanol. All samples were dried at 60 °C, powdered, treated with 1:1 chloroform: methanol, and dried again before isotope analysis. There were no differences in the values of δ13C and δ15N between the methods of preservation. Isotopic differences were absolutely small (δ13C = 0.1±0.10/00; δ15N=0.2±0.20/00, random in direction, and within the limits of analytical precision for the mass spectrometer. Preservation in ethanol thus appears to be an effective and efficient method for preserving blood samples for stable isotope analysis under field conditions. Abstract in Norwegian / Sammendrag:Konservering av blodprøver fra rein i 70% etanolløsning påvirker ikke verdiene av δ13C and δ15N–verdiene og er en fullgod metode for analyse av stabile isotoperVi sammenlignet to og to prøver av blodprøver fra 18 reinsdyr. Prøvene var enten konservert ved umiddelbar frysing eller ved bruk av 70% etanol. Alle prøver ble tørket ved 60 °C, pulverisert og behandlet med kloroform:metanol i forholdet 1:1. Til slutt ble de tørket på nytt før gjennomføring av isotopanalysen. Vi fant ingen forskjell i verdiene av δ13C and δ15N mellom de to konserveringsmetodene. I absolutte verdier var isotopforskjellene små (δ13C = 0.1±0.1 0/00; δ15N=0.2±0.2 0/00. Forskjellene var tilfeldige og innenfor grensene for massespektrometerets presisjon. Bruk av etanol framstår som en effektiv og fullgod metode til konservering av blodprøver for analyse av stabile isotoper under feltforhold.

  9. Effects of preservation methods of muscle tissue from upper-trophic level reef fishes on stable isotope values (δ13C and δ15N

    Directory of Open Access Journals (Sweden)

    Christopher D. Stallings

    2015-03-01

    Full Text Available Research that uses stable isotope analysis often involves a delay between sample collection in the field and laboratory processing, therefore requiring preservation to prevent or reduce tissue degradation and associated isotopic compositions. Although there is a growing literature describing the effects of various preservation techniques, the results are often contextual, unpredictable and vary among taxa, suggesting the need to treat each species individually. We conducted a controlled experiment to test the effects of four preservation methods of muscle tissue from four species of upper trophic-level reef fish collected from the eastern Gulf of Mexico (Red Grouper Epinephelus morio, Gag Mycteroperca microlepis, Scamp Mycteroperca phenax, and Red Snapper Lutjanus campechanus. We used a paired design to measure the effects on isotopic values for carbon and nitrogen after storage using ice, 95% ethanol, and sodium chloride (table salt, against that in a liquid nitrogen control. Mean offsets for both δ13C and δ15N values from controls were lowest for samples preserved on ice, intermediate for those preserved with salt, and highest with ethanol. Within species, both salt and ethanol significantly enriched the δ15N values in nearly all comparisons. Ethanol also had strong effects on the δ13C values in all three groupers. Conversely, for samples preserved on ice, we did not detect a significant offset in either isotopic ratio for any of the focal species. Previous studies have addressed preservation-induced offsets in isotope values using a mass balance correction that accounts for changes in the isotope value to that in the C/N ratio. We tested the application of standard mass balance corrections for isotope values that were significantly affected by the preservation methods and found generally poor agreement between corrected and control values. The poor performance by the correction may have been due to preferential loss of lighter isotopes

  10. Effects of preservation methods of muscle tissue from upper-trophic level reef fishes on stable isotope values (δ13C and δ15N)

    Science.gov (United States)

    Nelson, James A.; Rozar, Katherine L.; Adams, Charles S.; Wall, Kara R.; Switzer, Theodore S.; Winner, Brent L.; Hollander, David J.

    2015-01-01

    Research that uses stable isotope analysis often involves a delay between sample collection in the field and laboratory processing, therefore requiring preservation to prevent or reduce tissue degradation and associated isotopic compositions. Although there is a growing literature describing the effects of various preservation techniques, the results are often contextual, unpredictable and vary among taxa, suggesting the need to treat each species individually. We conducted a controlled experiment to test the effects of four preservation methods of muscle tissue from four species of upper trophic-level reef fish collected from the eastern Gulf of Mexico (Red Grouper Epinephelus morio, Gag Mycteroperca microlepis, Scamp Mycteroperca phenax, and Red Snapper Lutjanus campechanus). We used a paired design to measure the effects on isotopic values for carbon and nitrogen after storage using ice, 95% ethanol, and sodium chloride (table salt), against that in a liquid nitrogen control. Mean offsets for both δ13C and δ15N values from controls were lowest for samples preserved on ice, intermediate for those preserved with salt, and highest with ethanol. Within species, both salt and ethanol significantly enriched the δ15N values in nearly all comparisons. Ethanol also had strong effects on the δ13C values in all three groupers. Conversely, for samples preserved on ice, we did not detect a significant offset in either isotopic ratio for any of the focal species. Previous studies have addressed preservation-induced offsets in isotope values using a mass balance correction that accounts for changes in the isotope value to that in the C/N ratio. We tested the application of standard mass balance corrections for isotope values that were significantly affected by the preservation methods and found generally poor agreement between corrected and control values. The poor performance by the correction may have been due to preferential loss of lighter isotopes and corresponding

  11. Effects of preservation methods of muscle tissue from upper-trophic level reef fishes on stable isotope values (δ (13)C and δ (15)N).

    Science.gov (United States)

    Stallings, Christopher D; Nelson, James A; Rozar, Katherine L; Adams, Charles S; Wall, Kara R; Switzer, Theodore S; Winner, Brent L; Hollander, David J

    2015-01-01

    Research that uses stable isotope analysis often involves a delay between sample collection in the field and laboratory processing, therefore requiring preservation to prevent or reduce tissue degradation and associated isotopic compositions. Although there is a growing literature describing the effects of various preservation techniques, the results are often contextual, unpredictable and vary among taxa, suggesting the need to treat each species individually. We conducted a controlled experiment to test the effects of four preservation methods of muscle tissue from four species of upper trophic-level reef fish collected from the eastern Gulf of Mexico (Red Grouper Epinephelus morio, Gag Mycteroperca microlepis, Scamp Mycteroperca phenax, and Red Snapper Lutjanus campechanus). We used a paired design to measure the effects on isotopic values for carbon and nitrogen after storage using ice, 95% ethanol, and sodium chloride (table salt), against that in a liquid nitrogen control. Mean offsets for both δ (13)C and δ (15)N values from controls were lowest for samples preserved on ice, intermediate for those preserved with salt, and highest with ethanol. Within species, both salt and ethanol significantly enriched the δ (15)N values in nearly all comparisons. Ethanol also had strong effects on the δ (13)C values in all three groupers. Conversely, for samples preserved on ice, we did not detect a significant offset in either isotopic ratio for any of the focal species. Previous studies have addressed preservation-induced offsets in isotope values using a mass balance correction that accounts for changes in the isotope value to that in the C/N ratio. We tested the application of standard mass balance corrections for isotope values that were significantly affected by the preservation methods and found generally poor agreement between corrected and control values. The poor performance by the correction may have been due to preferential loss of lighter isotopes and

  12. Carbon, Nitrogen and Sulphur concentration and δ13C, δ15N values in Hypogymnia physodes within the montane area - preliminary data

    Science.gov (United States)

    Ciężka, Monika; Kossowska, Maria; Paneth, Piotr; Górka, Maciej

    2016-12-01

    The contribution of C, N and S, as well as the isotopic composition of C and N of atmospheric pollutants, are assumed to be reflected in the organic compounds inbuilt into the lichen thallus. The chemical and isotopic analyses were carried out on lichen Hypogymnia physodes samples gathered from Picea abies and Larix decidua, collected in 13 sampling points located in Karkonoski National Park and its closest vicinity in 2011. The results for %C, %N and %S varied from 43.44 to 46.79%, from 0.86 to 1.85% and from 0.07 to 0.27 %, respectively. The δ13C values ranged from -26.6 to -24.6‰, whereas δ15N values varied from -13.0 to -6.8‰. The ranges in isotope composition suggest different sources of C and N for Karpacz compared to the remaining sampling sites. For Karpacz, the δ13C values suggest (in case the fractionation product-substrate does not exist and Δ=0) that the dominant sources are coal combustion processes, whereas for remaining sampling points, the δ13C values are ambiguous and are masked by many mixed natural and anthropogenic processes. With the same assumption that Δ=0, the δ15N values suggest that transport is not a dominant source of nitrogen within Karpacz city. Moreover, in this study we tested the possible fractionation (Δ) for carbon and nitrogen, assuming that within the investigated area, the source of carbon is probably CO2 and/or DIC (HCO3-) dissolved in precipitation, while the source of nitrogen is NOx and/or NO3- ion. The calculated fractionation factors were: (i) for gaseous carbon compounds ΔCO2-Corg value from -13.4 to -11.4‰, whereas for the ions form ΔHCO3--Corg value from -16.6 to -14.6‰, (ii) for nitrogen gaseous compounds ΔNOx-Norg value between apx. -17 and -5‰, whereas for the ions form ΔNO3--Norg value between -9.9 and -3.7‰.

  13. 13C/12C and 15N/14N isotope analysis to characterize degradation of atrazine: evidence from parent and daughter compound values.

    Science.gov (United States)

    Meyer, Armin H; Elsner, Martin

    2013-07-02

    Atrazine (Atz) and its metabolite desethylatrazine (DEA) frequently occur in the environment. Conclusive interpretation of their transformation is often difficult. This study explored evidence from (13)C/(12)C and (15)N/(14)N isotope trends in parent and daughter compounds when Atz was dealkylated by (i) permanganate and (ii) the bacterium Rhodococcus sp. NI86/21. In both transformations, (13)C/(12)C ratios of atrazine increased strongly (ε(carbon/permanganate) = -4.6 ± 0.6‰ and ε(carbon/Rhodoccoccus) = -3.8 ± 0.2‰), whereas nitrogen isotope fractionation was small. (13)C/(12)C ratios of DEA showed the following trends. (i) When DEA was formed as the only product (Atz + permanganate), (13)C/(12)C remained constant, close to the initial value of Atz, because the carbon atoms involved in the reaction step are not present in DEA. (ii) When DEA was formed together with desisopropylatrazine (biodegradation of Atz), (13)C/(12)C increased but only within 2‰. (iii) When DEA was further biodegraded, (13)C/(12)C increased by up to 9‰ giving strong testimony of the metabolite's breakdown. Two lines of evidence emerge. (a) Enrichment of (13)C/(12)C in DEA, compared to initial Atz, may contain evidence of further DEA degradation. (b) Dual element ((15)N/(14)N versus (13)C/(12)C) isotope plots for dealkylation of atrazine agree with indirect photodegradation but differ from direct photolysis and biotic hydrolysis. Trends in multielement isotope data of atrazine may, therefore, decipher different degradation pathways.

  14. Correlation between the synthetic origin of methamphetamine samples and their {sup 15}N and {sup 13}C stable isotope ratios

    Energy Technology Data Exchange (ETDEWEB)

    Billault, Isabelle [Laboratoire d' Analyse Isotopique et Electrochimique de Metabolismes, CNRS UMR6006, University of Nantes, BP 92208, 44322 Nantes (France)]. E-mail: Isabelle.Billault@univ-nantes.fr; Courant, Frederique [Laboratoire d' Analyse Isotopique et Electrochimique de Metabolismes, CNRS UMR6006, University of Nantes, BP 92208, 44322 Nantes (France); Pasquereau, Leo [Laboratoire d' Analyse Isotopique et Electrochimique de Metabolismes, CNRS UMR6006, University of Nantes, BP 92208, 44322 Nantes (France); Derrien, Solene [Laboratoire d' Analyse Isotopique et Electrochimique de Metabolismes, CNRS UMR6006, University of Nantes, BP 92208, 44322 Nantes (France); Robins, Richard J. [Laboratoire d' Analyse Isotopique et Electrochimique de Metabolismes, CNRS UMR6006, University of Nantes, BP 92208, 44322 Nantes (France); Naulet, Norbert [Laboratoire d' Analyse Isotopique et Electrochimique de Metabolismes, CNRS UMR6006, University of Nantes, BP 92208, 44322 Nantes (France)

    2007-06-12

    The active ingredient of ecstasy, N-methyl-3,4-methyldioxyphenylisopropylamine (MDMA) can be manufactured by a number of easy routes from simple precursors. We have synthesised 45 samples of MDMA following the five most common routes using N-precursors from 12 different origins and three different precursors for the aromatic moiety. The {sup 13}C and {sup 15}N contents of both the precursors and the MDMA samples derived therefrom were measured by isotope ratio mass spectrometry coupled to an elemental analyser (EA-IRMS). We show that within-pathway correlation between the {sup 15}N content of the precursor and that of the derived MDMA can be strong but that no general pattern of correlation can be defined. Rather, it is evident that the {delta} {sup 15}N values of MDMA are strongly influenced by a combination of the {delta} {sup 15}N values of the source of nitrogen used, the route by which the MDMA is synthesised, and the experimental conditions employed. Multivariate analysis (PCA) based on the {delta} {sup 15}N values of the synthetic MDMA and of the {delta} {sup 15}N and {delta} {sup 13}C values of the N-precursors leads to good discrimination between the majority of the reaction conditions tested.

  15. Correlation between the synthetic origin of methamphetamine samples and their 15N and 13C stable isotope ratios.

    Science.gov (United States)

    Billault, Isabelle; Courant, Frédérique; Pasquereau, Léo; Derrien, Solène; Robins, Richard J; Naulet, Norbert

    2007-06-12

    The active ingredient of ecstasy, N-methyl-3,4-methyldioxyphenylisopropylamine (MDMA) can be manufactured by a number of easy routes from simple precursors. We have synthesised 45 samples of MDMA following the five most common routes using N-precursors from 12 different origins and three different precursors for the aromatic moiety. The 13C and 15N contents of both the precursors and the MDMA samples derived therefrom were measured by isotope ratio mass spectrometry coupled to an elemental analyser (EA-IRMS). We show that within-pathway correlation between the 15N content of the precursor and that of the derived MDMA can be strong but that no general pattern of correlation can be defined. Rather, it is evident that the delta15N values of MDMA are strongly influenced by a combination of the delta15N values of the source of nitrogen used, the route by which the MDMA is synthesised, and the experimental conditions employed. Multivariate analysis (PCA) based on the delta15N values of the synthetic MDMA and of the delta15N and delta13C values of the N-precursors leads to good discrimination between the majority of the reaction conditions tested.

  16. The δ15N and δ18O values of N2O produced during the co-oxidation of ammonia by methanotrophic bacteria

    Science.gov (United States)

    Mandernack, Kevin W.; Mills, Christopher T.; Johnson, Craig A.; Rahn, Thomas; Kinney, Chad

    2009-01-01

    In order to determine if the δ15N and δ18O values of N2O produced during co-oxidation of NH4+ by methanotrophic (methane oxidizing) bacteria can be isotopically distinguished from N2O produced either by autotrophic nitrifying or denitrifying bacteria, we conducted laboratory incubation experiments with pure cultures of methanotrophic bacteria that were provided NH4Cl as an oxidation substrate. The N2O produced during NH4+ oxidation by methanotrophic bacteria showed nitrogen isotope fractionation between NH4+ and N2O (εN2O–NH4+) of − 48 and − 55‰ for Methylomonas methanica and Methylosinus trichosporium, OB3b respectively. These large fractionations are similar to those previously measured for autotrophic nitrifying bacteria and consistent with N2O formation by multiple rate limiting steps that include NH4+oxidation by the methane monooxygenase enzyme and reduction of NO2− to N2O. Consequently, N2O formed by NH4+ oxidation via methanotrophic or autotrophic nitrifying bacteria might generally be characterized by lower δ15NN2O values than that formed by denitrificaiton, although this also depends on the variability of δ15N of available nitrogen sources (e.g., NH4+, NO3−, NO2−). Additional incubations with M. trichosporium OB3b at high and low CH4 conditions in waters of different δ18O values revealed that 19–27% of the oxygen in N2O was derived from O2 with the remainder from water. The biochemical mechanisms that could explain this amount of O2 incorporation are discussed. The δ18O of N2O formed under high CH4 conditions was ~ + 15‰ more positive than that formed under lower CH4 conditions. This enrichment resulted in part from the incorporation of O2 into N2O that was enriched in 18O due to an isotope fractionation effect of − 16.1 ± 2.0‰ and − 17.5 ± 5.4‰ associated with O2 consumption during the high and low methane concentration incubations, respectively. Therefore, N2O formed by NH4+

  17. Foliar and fungal 15N:14N ratios reflect development of mycorrhizae and nitrogen supply during primary succession: testing analytical models.

    Science.gov (United States)

    Hobbie, Erik A; Jumpponen, Ari; Trappe, Jim

    2005-12-01

    Nitrogen isotopes (15N/14N ratios, expressed as delta15N values) are useful markers of the mycorrhizal role in plant nitrogen supply because discrimination against 15N during creation of transfer compounds within mycorrhizal fungi decreases the 15N/14N in plants (low delta15N) and increases the 15N/14N of the fungi (high delta15N). Analytical models of 15N distribution would be helpful in interpreting delta15N patterns in fungi and plants. To compare different analytical models, we measured nitrogen isotope patterns in soils, saprotrophic fungi, ectomycorrhizal fungi, and plants with different mycorrhizal habits on a glacier foreland exposed during the last 100 years of glacial retreat and on adjacent non-glaciated terrain. Since plants during early primary succession may have only limited access to propagules of mycorrhizal fungi, we hypothesized that mycorrhizal plants would initially be similar to nonmycorrhizal plants in delta15N and then decrease, if mycorrhizal colonization were an important factor influencing plant delta15N. As hypothesized, plants with different mycorrhizal habits initially showed similar delta15N values (-4 to -6 per thousand relative to the standard of atmospheric N2 at 0 per thousand), corresponding to low mycorrhizal colonization in all plant species and an absence of ectomycorrhizal sporocarps. In later successional stages where ectomycorrhizal sporocarps were present, most ectomycorrhizal and ericoid mycorrhizal plants declined by 5-6 per thousand in delta15N, suggesting transfer of 15N-depleted N from fungi to plants. The values recorded (-8 to -11 per thousand) are among the lowest yet observed in vascular plants. In contrast, the delta15N of nonmycorrhizal plants and arbuscular mycorrhizal plants declined only slightly or not at all. On the forefront, most ectomycorrhizal and saprotrophic fungi were similar in delta15N (-1 to -3 per thousand), but the host-specific ectomycorrhizal fungus Cortinarius tenebricus had values of up to 7

  18. A new method to track seed dispersal and recruitment using 15N isotope enrichment.

    Science.gov (United States)

    Carlo, Tomás A; Tewksbury, Joshua J; Martínez Del Río, Carlos

    2009-12-01

    Seed dispersal has a powerful influence on population dynamics, genetic structuring, evolutionary rates, and community ecology. Yet, patterns of seed dispersal are difficult to measure due to methodological shortcomings in tracking dispersed seeds from sources of interest. Here we introduce a new method to track seed dispersal: stable isotope enrichment. It consists of leaf-feeding plants with sprays of 15N-urea during the flowering stage such that seeds developed after applications are isotopically enriched. We conducted a greenhouse experiment with Solanum americanum and two field experiments with wild Capsicum annuum in southern Arizona, USA, to field-validate the method. First, we show that plants sprayed with 15N-urea reliably produce isotopically enriched progeny, and that delta 15N (i.e., the isotopic ratio) of seeds and seedlings is a linear function of the 15N-urea concentration sprayed on mothers. We demonstrate that three urea dosages can be used to distinctly enrich plants and unambiguously differentiate their offspring after seeds are dispersed by birds. We found that, with high urea dosages, the resulting delta 15N values in seedlings are 10(3) - 10(4) times higher than the delta 15N values of normal plants. This feature allows tracking not only where seeds arrive, but in locations where seeds germinate and recruit, because delta 15N enrichment is detectable in seedlings that have increased in mass by at least two orders of magnitude before fading to normal delta 15N values. Last, we tested a mixing model to analyze seed samples in bulk. We used the delta 15N values of batches (i.e., combined seedlings or seeds captured in seed traps) to estimate the number of enriched seeds coming from isotopically enriched plants in the field. We confirm that isotope enrichment, combined with batch-sampling, is a cheap, reliable, and user-friendly method for bulk-processing seeds and is thus excellent for the detection of rare dispersal events. This method could

  19. 13C/12C and 15N/14N Isotope Analysis to Characterize Natural Degradation of Atrazine: Evidence from Parent and Daughter Compound Values

    Science.gov (United States)

    Elsner, Martin; Meyer, Armin

    2013-04-01

    The mobile and still herbicidal metabolites desethylatrazine (DEA) and desisopropylatrazine (DIA) are frequently detected together with its parent compound atrazine (Atz) in the aquatic environment. Interpretation of their transformation state is often difficult with current methods, which are mainly measuring concentrations. Alternatively, compound specific isotope analyses (CSIA) has become a novel tool to detect degradation processes of contaminants in groundwater. The aim of our study was to investigate on the lab scale 13C/12C and 15N/14N isotope trends in parent and daughter compounds associated with different degradation scenarios of atrazine likely to occur in the environment. Thus atrazine was dealkylated with (i) permanganate and (ii) the bacterium Rhodococcus sp. NI86/21. In both transformations, 13C/12C ratios of atrazine increased strongly (epsilon carbon/permanganate = -4.6 ± 0.6 ‰ and epsilon carbon/Rhodoccoccus = -3.8 ± 0.2 ‰) whereas nitrogen isotope fractionation was small. 13C/12C ratios of DEA showed the following trends. (i) When DEA was formed as only product (Atz + permanganate) 13C/12C remained constant, close to the initial value of Atz. (ii) When DEA was formed together with deisopropylatrazine (biodegradation of Atz) 13C/12C increased, but only within 2‰. (iii) When DEA and DIA was further biodegraded, 13C/12C increased for both metabolites up to 9‰. Thus strong enrichment of 13C/12C in the metabolites in comparison to Atz can give strong testimony for further breakdown of the metabolite.

  20. {sup 15}N/{sup 14}N isotopic ratio and statistical analysis: an efficient way of linking seized Ecstasy tablets

    Energy Technology Data Exchange (ETDEWEB)

    Palhol, Fabien; Lamoureux, Catherine; Chabrillat, Martine; Naulet, Norbert

    2004-05-10

    In this study, the {sup 15}N/{sup 14}N isotopic ratios of 106 samples of 3,4-methylenedioxymethamphetamine (MDMA) extracted from Ecstasy tablets are presented. These ratios, measured using gas chromatography-combustion-isotope ratio mass spectrometry (GC-C-IRMS), show a large discrimination between samples with a range of {delta}{sup 15}N values between -17 and +19%o, depending on the precursors and the method used in clandestine laboratories. Thus, {delta}{sup 15}N values can be used in a statistical analysis carried out in order to link Ecstasy tablets prepared with the same precursors and synthetic pathway. The similarity index obtained after principal component analysis and hierarchical cluster analysis appears to be an efficient way to group tablets seized in different places.

  1. (15)N natural abundance of non-fixing woody species in the Brazilian dry forest (caatinga).

    Science.gov (United States)

    de Freitas, Ana Dolores Santiago; de Sa Barretto Sampaio, Everardo Valadares; Menezes, Romulo Simoes Cezar; Tiessen, Holm

    2010-06-01

    Foliar delta(15)N values are useful to calculate N(2) fixation and N losses from ecosystems. However, a definite pattern among vegetation types is not recognised and few data are available for semi-arid areas. We sampled four sites in the Brazilian caatinga, along a water availability gradient. Sites with lower annual rainfall (700 mm) but more uniform distribution (six months) had delta(15)N values of 9.4 and 10.1 per thousand, among the highest already reported, and significantly greater than those (6.5 and 6.3 per thousand) of sites with higher rainfall (800 mm) but less uniform distribution (three months). There were no significant differences at each site among species or between non-fixing legume and non-legume species, in spite of the higher N content of the first group. Therefore, they constitute ideal reference plants in estimations of legume N(2) fixation. The higher values could result from higher losses of (15)N depleted gases or lower losses of enriched (15)N material.

  2. Analysis of historical delta values for IAEA/LANL NDA training courses

    Energy Technology Data Exchange (ETDEWEB)

    Geist, William [Los Alamos National Laboratory; Santi, Peter [Los Alamos National Laboratory; Swinhoe, Martyn [Los Alamos National Laboratory; Bonner, Elisa [FORMER N-4 STUDENT

    2009-01-01

    The Los Alamos National Laboratory (LANL) supports the International Atomic Energy Agency (IAEA) by providing training for IAEA inspectors in neutron and gamma-ray Nondestructive Assay (NDA) of nuclear material. Since 1980, all new IAEA inspectors attend this two week course at LANL gaining hands-on experience in the application of NDA techniques, procedures and analysis to measure plutonium and uranium nuclear material standards with well known pedigrees. As part of the course the inspectors conduct an inventory verification exercise. This exercise provides inspectors the opportunity to test their abilities in performing verification measurements using the various NDA techniques. For an inspector, the verification of an item is nominally based on whether the measured assay value agrees with the declared value to within three times the historical delta value. The historical delta value represents the average difference between measured and declared values from previous measurements taken on similar material with the same measurement technology. If the measurement falls outside a limit of three times the historical delta value, the declaration is not verified. This paper uses measurement data from five years of IAEA courses to calculate a historical delta for five non-destructive assay methods: Gamma-ray Enrichment, Gamma-ray Plutonium Isotopics, Passive Neutron Coincidence Counting, Active Neutron Coincidence Counting and the Neutron Coincidence Collar. These historical deltas provide information as to the precision and accuracy of these measurement techniques under realistic conditions.

  3. High and low value fish chains in the Mekong Delta: challenges for livelihoods and governance

    NARCIS (Netherlands)

    Vo Thi Thanh Loc,; Bush, S.R.; Xuan Sinh, Le; Nguyen Tri Khiem,

    2010-01-01

    This paper investigates the structure, function and wealth distribution within the Pangasius hypophthalmus and Henicorhynchus spp./Labiobarbus spp. value chains in the Mekong Delta of Vietnam. The analysis is driven by key questions relating to the form and function of value chains, their contributi

  4. Carbon isotope ratio (delta13C) values of urinary steroids for doping control in sport.

    Science.gov (United States)

    Cawley, Adam T; Trout, Graham J; Kazlauskas, Rymantas; Howe, Christopher J; George, Adrian V

    2009-03-01

    The detection of steroids originating from synthetic precursors in relation to their chemically identical natural analogues has proven to be a significant challenge for doping control laboratories accredited by the World Anti-Doping Agency (WADA). Endogenous steroid abuse may be confirmed by utilising the atomic specificity of gas chromatography-combustion-isotope ratio mass spectrometry (GC-C-IRMS) that enables the precise measurement of differences in stable isotope ratios that arise as a result of fractionation patterns inherent in the source of steroids. A comprehensive carbon isotope ratio (delta(13)C) profiling study (n=1262) of urinary ketosteroids is reported that demonstrates the inter-individual variation that can be expected from factors such as diet, ethnicity, gender and age within and between different populations (13 countries). This delta(13)C distribution is shown by principal component analysis (PCA) to provide a statistical comparison to delta(13)C values observed following administration of testosterone enanthate. A limited collection of steroid diol data (n=100; consisting of three countries) is also presented with comparison to delta(13)C values of excreted testosterone to validate criteria for WADA accredited laboratories to prove doping offences.

  5. Organosolv extraction of lignin from hydrolyzed almond shells and application of the delta-value theory.

    Science.gov (United States)

    Quesada-Medina, Joaquín; López-Cremades, Francisco Javier; Olivares-Carrillo, Pilar

    2010-11-01

    The solubility of lignin from hydrolyzed almond (Prunus amygdalus) shells in different acetone, ethanol and dioxane-water mixtures and conditions (extraction time and temperature) was studied. The concept of the solubility parameter (delta-value) was applied to explain the effect of organic solvent concentration on lignin solubility. The organic solvent-water mixture that led to the highest lignin extraction was composed of a 75% vol. of organic solvent for all the solvent series investigated (acetone, ethanol and dioxane). Moreover, the best lignin extraction conditions were a temperature of 210 degrees C and an extraction time of 40 min for the acetone and ethanol series, and 25 min for the dioxane series. The delta-value of the hydrolyzed almond shell lignin [14.60 (cal/cm(3))(1/2)] and that of the organic solvent-water mixtures was calculated. The experimental delignification capacity of the aqueous organic solvents clearly reflected the proximity of their delta-value to that of lignin. The hydrogen-bonding capacity of the solvent-water mixtures was also taken into account. Copyright 2010 Elsevier Ltd. All rights reserved.

  6. CCQM-K140: carbon stable isotope ratio delta values in honey

    Science.gov (United States)

    Dunn, P. J. H.; Goenaga-Infante, H.; Goren, A. C.; Şimşek, A.; Bilsel, M.; Ogrinc, N.; Armishaw, P.; Hai, L.

    2017-01-01

    As there can be small but measureable differences in isotope ratios between different sources of the same element/compound/material, isotope ratio measurements are applied in a number of different fields including archaeology, environmental science, geochemistry, forensic science and ecology. Isotope ratios for the light elements (H, C, N, O and S) are typically reported as δ-values which are isotope ratios expressed relative to an internationally agreed standard (this standard is the zero-point on the scale), although absolute isotope ratios which are traceable to the SI have also been reported. The IAWG has been granted a traceability exception for the use of arbitrary delta scales until SI traceability can be established at the required level of uncertainty but this goal is some years away. While the CCQM IAWG has previously organised several pilot studies on isotope ratio determination (CCQM-P75: Stable isotope delta values in methionine, 2006; CCQM-P105: Sr isotope ratios in wine, 2008; CCQM-K98: Pb isotope ratios in bronze with additional delta values in CCQM-P134, 2011), it has been a number of years since delta values of light elements have been considered and there has been no key comparison (KC). Therefore, the IAWG has included the need for a KC (CCQM-K140) based on an arbitrary delta scale in its program to support ongoing requirements to demonstrate core capabilities as well as specific claims of measurement capability (CMCs) in this area. The performance of all five of the CCQM-K140 participants was very good, illustrating their ability to obtain accurate results for carbon isotope ratios, within the calibration range afforded by internationally agreed reference materials (δ13CVPDB-LSVEC between ‑47.32 % and +535.3 %) with measurement uncertainties of between 0.08 and 0.28 %. This was despite the fact that no two participants used exactly the same approach in terms of instrumentation or data treatment. Main text To reach the main text of this

  7. Ecosystem Service Value for the Common Reed Wetlands in the Liaohe Delta, Northeast China

    DEFF Research Database (Denmark)

    Ye, Siyuan; Laws, Edward A.; Costanza, Robert;

    2016-01-01

    and societal developments. Although the direct and indirect services provided by such wetlands make valuable contributions to human welfare, wetlands are often given little weight in policy decisions, because ecosystem services are not fully “captured” in commercial markets or adequately quantified in terms...... comparable with the values of economic services and manufactured capital. In this study the value of 10 of 17 ecosystem services provided by the reed wetlands in the Liaohe Delta was estimated by using market pricing, shadow projects, and benefit transfer methods. The value of the 10 services provided...... by the 800 km2 of reed wetland totaled approximately US $2.68 billion. Remarkably, aquaculture and the production of pulp from reeds accounted for only 19% of the total value of the reed wetland services. About 32% of the value of the ecosystem services was attributed to non-consumptive recreation, an easily...

  8. Addendum to "Determination of $\\gamma$-ray widths in $^{15}$N using nuclear resonance fluorescence''

    CERN Document Server

    Szücs, Tamás

    2015-01-01

    The determination of absolute widths of two observed levels above the proton threshold in $^{15}$N has been improved by a combined analysis of our recent $^{15}$N($\\gamma$,$\\gamma'$)$^{15}$N$^\\ast$ photon scattering data, resonance strengths $\\omega\\gamma$ of the $^{14}$C($p$,$\\gamma$)$^{15}$N reaction, and $\\gamma$-ray branchings $b_{\\gamma,i}$ in $^{15}$N. The revised data are compared to the adopted values, and some inconsistencies in the adopted values are illustrated.

  9. Appraisal of {sup 15}N enrichment and {sup 15}N natural abundance methods for estimating N{sub 2} fixation by understorey Acacia leiocalyx and A. disparimma in a native forest of subtropical Australia

    Energy Technology Data Exchange (ETDEWEB)

    Bai, Shahla Hosseini; Xu, Zhihong; Blumfield, Timothy J. [Griffith Univ., Nathan, Brisbane, QLD (Australia). School of Biomolecular and Physical Sciences, Environmental Futures Centre; Sun, Fangfang [Guangdong Academy of Agricultural Sciences, Guangzhou (China). Research Centre for Quality, Safety and Standard of Agricultural Products; Chen, Chengrong [Griffith Univ., Nathan, Brisbane, QLD (Australia). School of Environment, Environmental Futures Centre; Wild, Clyde [Griffith Univ., Gold Coast, QLD (Australia). School of Environment, Environmental Futures Centre

    2012-05-15

    Purpose: It is anticipated that global climate change will increase the frequency of wildfires in native forests of eastern Australia. Understorey legumes such as Acacia species play an important role in maintaining ecosystem nitrogen (N) balance through biological N fixation (BNF). This is particularly important in Australian native forests with soils of low nutrient status and frequent disturbance of the nutrient cycles by fires. This study aimed to examine {sup 15}N enrichment and {sup 15}N natural abundance techniques in terms of their utilisation for evaluation of N{sub 2} fixation of understorey acacias and determine the relationship between species ecophysiological traits and N{sub 2} fixation. Materials and methods: A trial was established at sites 1 and 2 located at Toohey Forest, Queensland, Australia, a eucalypt-dominated native forest, to examine the determination of BNF using {sup 15}N enrichment and {sup 15}N natural abundance methods. Toohey Forest is an urban forest and subjected to frequent fuel reduction burns to protect the adjacent properties. Plant physiological status was measured to determine the relationship between physiological and N{sub 2} fixation activities. Results and discussion: Both {sup 15}N enrichment and {sup 15}N natural abundance techniques may be used to estimate N{sub 2} fixation of acacia tree species. The estimation of BNF using {sup 15}N enrichment was higher than those of the {sup 15}N natural abundance method. A grass reference plant, Themeda triandra, as well as tree reference plants provided an appropriate {delta}{sup 15}N signal. Potential B values for Acacia spp. between -0.3 permille and 1.0 permille provided an acceptable BNF estimation. This suburban forest is located nearby a busy highway leading to N deposition over time with consequent negative {delta}{sup 15}N signal. This N deposition may explain the separation between the {delta}{sup 15}N signal of the acacias and that of the reference plants which led to

  10. Phenylalanine δ15N in Paleo Archives as a New Proxy for δ15N of Exported Primary Production

    Science.gov (United States)

    McCarthy, M.; Batista, F. C.; Vokhshoori, N. L.; Brown, J. T.; Guilderson, T. P.; Ravelo, A. C.; Sherwood, O.

    2012-12-01

    Compound-specific isotope analysis of individual amino acids (CSI-AA) is emerging as a powerful new tool for studying the paleo nitrogen cycle. Because most detrital organic nitrogen is composed of amino acids, CSI-AA can reveal the mechanistic basis for organic nitrogen diagenesis, preserve a record of past food web structure, and potentially reconstruct the δ15N values of past nitrate and primary production. Within the commonly measured amino acids, the δ15N value of phenylalanine (Phe) appears uniquely promising as a new proxy that reflects the nitrogen isotopic value of the original source. Phe δ15N values remain almost unchanged with trophic transfer through food webs, and also during at least the initial stages of organic matter degradation. Here we synthesize results from both bio-archives and recent sediments, which together suggest that at least in Holocene archives the Phe δ15N value does in fact record the average inorganic nitrogen δ15N value at the base of planktonic food webs. However, several important unknowns also remain. These include the extent of variation in amino acid isotopic fractionation patterns in phylogenetically distinct algal groups. The stability of Phe δ15N values in older sediments where organic matter has undergone extensive diagenesis is also an important research area, which may ultimately establish the temporal limit for application of this approach to study past geological epochs. Together, however, results to date suggest that of Phe δ15N values in paleo archives represent a novel molecular-level proxy which is not tied to any specific organism or group, but rather can provide an integrated estimate of δ15N value of exported primary production.

  11. Nitrogen input 15N-signatures are reflected in plant 15N natural abundances of N-rich tropical forest in China

    Science.gov (United States)

    Abdisa Gurmesa, Geshere; Lu, Xiankai; Gundersen, Per; Yunting, Fang; Mo, Jiangming

    2016-04-01

    In this study, we tested the measurement of natural abundance of 15N15N) for its ability to assess changes in N cycling due to increased N deposition in two forest types; namely, an old-growth broadleaved forest and a pine forest, in southern China. We measured δ15N values of inorganic N in input and output fluxes under ambient N deposition, and N concentration and δ15N of major ecosystem compartments under ambient and increased N deposition. Our results showed that N deposition to the forests was 15N-depleted, and was dominated by NH4-N. Plants were 15N-depleted due to imprint from the 15N-depleted atmospheric N deposition. The old-growth forest had larger N concentration and was more 15N-enriched than the pine forest. Nitrogen addition did not significantly affect N concentration, but it significantly increased δ15N values of plants, and slightly more so in the pine forest, toward the 15N signature of the added N in both forests. The result indicates that the pine forest may rely more on the 15N-depleted deposition N. Soil δ15N values were slightly decreased by the N addition. Our result suggests that ecosystem δ15N is more sensitive to the changes in ecosystem N status and N cycling than N concentration in N-saturated sub-tropical forests.

  12. Natural abundances of 15N and 13C in leaves of some N2-fixing and non-N2-fixing trees and shrubs in Syria.

    Science.gov (United States)

    Kurdali, F; Al-Shamma'a, M

    2009-09-01

    A survey study was conducted on man-made plantations located at two different areas in the arid region of Syria to determine the variations in natural abundances of the (15)N and (13)C isotopes in leaves of several woody legume and non-legume species, and to better understand the consequence of such variations on nitrogen fixation and carbon assimilation. In the first study area (non-saline soil), the delta(15)N values in four legume species (Acacia cyanophylla,-1.73 per thousand Acacia farnesiana,-0.55 per thousand Prosopis juliflora,-1.64 per thousand; and Medicago arborea,+1.6 \\textperthousand) and one actinorhizal plant (Elaeagnus angustifolia,-0.46 to-2.1 per thousand) were found to be close to that of the atmospheric value pointing to a major contribution of N(2) fixing in these species; whereas, delta(15)N values of the non-fixing plant species were highly positive. delta(13)C per thousand; in leaves of the C3 plants were found to be affected by plant species, ranging from a minimum of-28.67 per thousand; to a maximum of-23 per thousand. However, they were relatively similar within each plant species although they were grown at different sites. In the second study area (salt affected soil), a higher carbon discrimination value (Delta(13)C per thousand) was exhibited by P. juliflora, indicating that the latter is a salt tolerant species; however, its delta(15)N was highly positive (+7.03 per thousand) suggesting a negligible contribution of the fixed N(2). Hence, it was concluded that the enhancement of N(2) fixation might be achieved by selection of salt-tolerant Rhizobium strains.

  13. Stable carbon isotope analysis ({delta}{sup 13}C values) of polybrominated diphenyl ethers and their UV-transformation products

    Energy Technology Data Exchange (ETDEWEB)

    Rosenfelder, Natalie; Bendig, Paul [University of Hohenheim, Institute of Food Chemistry (170b), Garbenstr. 28, D-70599 Stuttgart (Germany); Vetter, Walter, E-mail: walter.vetter@uni-hohenheim.de [University of Hohenheim, Institute of Food Chemistry (170b), Garbenstr. 28, D-70599 Stuttgart (Germany)

    2011-10-15

    Polybrominated diphenyl ethers (PBDEs) are frequently detected in food and environmental samples. We used compound specific isotope analysis to determine the {delta}{sup 13}C values of individual PBDEs in two technical mixtures. Within the same technical product (DE-71 or DE-79), BDE congeners were the more depleted in {sup 13}C the higher brominated they were. In contrast, the products of light-induced hydrodebromination of BDE 47 and technical DE-79 were more enriched in {sup 13}C because of more stable bonds between {sup 13}C and bromine. As a result, the {delta}{sup 13}C values of the irradiated solution progressed diametrically compared to those of the technical synthesis. The ratio of the {delta}{sup 13}C values of BDE 47 to BDE 99 and of BDE 99 to BDE 153 are thus suggested as indicators to distinguish native technical products from transformation products. Ratios <1 are typical for native congeners (e.g. in DE-71) while the reversed ratio (>1) is typical of transformation products. - Highlights: > {delta}{sup 13}C values of PBDEs were determined by means of compound specific isotope analysis. > PBDEs in technical mixtures were the more depleted in {sup 13}C the higher they were brominated. > Solutions of individual PBDEs and technical PBDE mixtures were irradiated by UV light. > {delta}{sup 13}C values of irradiated PBDEs and technical PBDEs progressed diametrically. > Ratios of the {delta}{sup 13}C values were used to distinguish native from transformed PBDEs. - Diametrically progressing {delta}{sup 13}C values in technical mixtures and UV-transformation products of DE-79 may be useful for source appointment of PBDEs in environmental samples

  14. Direct use values of selected vegetation resources in the Okavango delta wetland

    Directory of Open Access Journals (Sweden)

    G Mmopelwa

    2011-08-01

    Full Text Available The economic benefits generated by wetlands and the costs associated with their degradation or loss are frequently overlooked. This often leads to decisions that stimulate wetland conversion and degradation.  An important step towards correcting this situation and countering this neglect is to establish the true values of a wetland’s ecosystem goods and services.  This study attempts to estimate the direct use values of native plants, such as palm leaves for basketry, grass for thatching, fuelwood, edible fruits and plant parts used by three villages adjacent to the Okavango Delta during the 2003 calendar year.  Other sources of ecosystem goods and services, such as fishing, floodplain farming and tourism, were not considered in this study.  The average annual value per household of these harvested resources is generally higher than that of similar resources found in other southern African wetlands, owing to higher consumption rates. The overall total direct use value of plant resources, including household income contributions “in kind”, was estimated at US$1 434 per household for 2003 (or US$43.41/ha. This value is almost equal to the average household financial income of US$1 416/year. The net present value of the overall benefit from the direct use of the vegetative resources is estimated at US$101.9 million. This clearly indicates the value of the use of natural resources and their contribution to livelihoods and quality of life.  This value is so significant that economic development planners ought to incorporate it into development planning. They should not conceive infrastructure development that would jeopardise the communities’ access to these natural resources without any well-developed mitigation strategy.

  15. Bradyrhizobium strain and the {sup 15}N natural abundance quantification of biological N{sub 2} fixation in soybean

    Energy Technology Data Exchange (ETDEWEB)

    Guimaraes, Ana Paula [Universidade Estadual do Norte Fluminense (UENF), Campos dos Goytacases, RJ (Brazil). Centro de Ciencias e Tecnologias Agropecuarias (CCTA). Dept. de Producao Vegetal; Morais, Rafael Fiusa de; Urquiaga, Segundo; Boddey, Robert Michael; Alves, Bruno Jose Rodrigues [EMBRAPA Agrobiologia, Seropedica, RJ (Brazil)]. E-mail: bruno@cnpab.embrapa.br

    2008-09-15

    In commercial plantations of soybean in both the Southern and the Cerrado regions, contributions from biological nitrogen fixation (BNF) are generally proportionately high. When using the {sup 15}N natural abundance technique to quantify BNF inputs, it is essential to determine, with accuracy, the {sup 15}N abundance of the N derived from BNF (the 'B' value). This study aimed to determine the effect of four recommended strains of Bradyrhizobium spp. (two B. japonicum and two B. elkanii) on the 'B' value of soybean grown in pots in an open field using an equation based on the determination of {delta}{sup 15}N natural abundance in a non-labelled soil, and estimate of the contribution of BNF derived from the use of {sup 15}N-isotope dilution in soils enriched with {sup 15}N. To evaluate N{sub 2} fixation by soybean, three non-N{sub 2}-fixing reference crops were grown under the same conditions. Regardless of Bradyrhizobium strain, no differences were observed in dry matter, nodule weight and total N between labelled and non-labelled soil. The N{sub 2} fixation of the soybeans grown in the two soil conditions were similar. The mean 'B' values of the soybeans inoculated with the B. japonicum strains were -1.84 per mille and -0.50 per mille, while those inoculated with B. elkanii were -3.67 per mille and -1.0 per mille, for the shoot tissue and the whole plant, respectively. Finally, the 'B' value for the soybean crop varied considerably in function of the inoculated Bradyrhizobium strain, being most important when only the shoot tissue was utilised to estimate the proportion of N in the plant derived from N{sub 2} fixation. (author)

  16. The value of delta neutrophil index in young infants with febrile urinary tract infection

    Science.gov (United States)

    Lee, Jung Won; Kim, Seong Heon; Park, Se Jin; Lee, Keum Hwa; Park, Jae Hyon; Kronbichler, Andreas; Eisenhut, Michael; Kim, Ji Hong; Lee, Jong Wook; Shin, Jae Il

    2017-01-01

    Delta neutrophil index (DNI) is the fraction of circulating immature granulocytes, which reflects severe bacterial infections and septic condition but has not been studied in urinary tract infection (UTI). Here, we evaluated the value of DNI in predicting acute pyelonephritis (APN) or vesicoureteral reflux (VUR) using the data of 288 patients. Conventional inflammatory markers (white blood cell [WBC] count, erythrocyte sedimentation rate [ESR], C-reactive protein [CRP]), and DNI were measured. WBC, CRP, ESR and DNI were higher in APN than in lower UTI (p < 0.01). Multiple logistic-regression analyses showed that DNI was a predictive factor for areas of lack of uptake on dimercaptosuccinic acid (DMSA) scans (P < 0.01). The area under the receiver operating characteristic (AUC) was also high for DNI (0.622, 95% CI 0.558–0.687, P < 0.01) as well as for CRP (0.731, 95% CI 0.673–0.789, P < 0.01) for the prediction of DMSA defects. DNI demonstrated the highest area under the ROC curve for diagnosis of VUR (0.620, 95% CI 0.542–0.698, P < 0.01). To the best of our knowledge, this is a first study demonstrating that DNI can be used as a diagnostic marker to distinguish APN from lower UTI and function as a diagnostic marker indicative of VUR compared to other conventional markers. PMID:28169298

  17. Maternal attitudes and values to youth sexuality-related activities in Delta State, Nigeria.

    Science.gov (United States)

    Okonkwo, I P; Ilika, A I

    2003-09-01

    This descriptive study assessed maternal attitudes to youth-related activities in Delta State. Using an adapted questionnaire, 300 women with adolescent children were chosen through a multistage sampling technique and relevant data obtained regarding their socio-economic status, perceptions and values as well as their knowledge of basic reproductive health concerns. Most of the women interviewed (95%), believed it was very important that young people completed secondary education and another 72% said they would normally set rules in their homes regarding what young people should read or watch. Sixty-seven percent of those studied, discussed sexuality issues regularly with their adolescent children, though only 46.4% of them were comfortable discussing these issue and about 50% admitted having enough information in such discussions. Another 76% of the women would approve of their children receiving reproductive health information and service including contraceptive condoms. The mothers studied believed that guided reproductive health information and services should be routinely provided for young people. The findings strongly suggest that the mothers who are important stakeholders in Adolescent Health would most likely be supportive of youth programmes. Most of the findings differ from those of other studies, and a qualitative study would be carried out to identify the reasons for these interesting findings.

  18. Determination of the 2H/1H and 15N/14N ratios of Alkylpyrazines from coffee beans (Coffea arabica L. and Coffea canephoravar. robusta) by isotope ratio mass spectrometry.

    Science.gov (United States)

    Richling, Elke; Preston, Christina; Kavvadias, Dominique; Kahle, Kathrin; Heppel, Christopher; Hummel, Silvia; König, Thorsten; Schreier, Peter

    2005-10-05

    The delta15N(AIR) and delta2H(VSMOW) data for several alkylpyrazines formed during the roasting process of coffee are reported. Samples of commercially available roasted (n = 9) as well as self-roasted (n = 8) coffee beans (Coffea arabica L. and Coffea canephora var. robusta) of different origins were investigated. By use of extracts prepared by simultaneous distillation extraction (SDE) and subsequently fractionated by liquid chromatography on silica gel, on-line capillary gas chromatography-isotope ratio mass spectrometry was employed in the combustion (C) and pyrolysis (P) modes (HRGC-C/P-IRMS) to determine the delta15N(AIR) and delta2H(VSMOW) values, respectively. In addition to the constituents of coffee beans, data for commercial synthetic alkylpyrazines and substances declared to be "natural" were determined. The delta15N(AIR) data for coffee alkylpyrazines under study-2-ethyl-5-methylpyrazine (1) and 2-ethyl-6-methylpyrazine (2) (measured as sum 1/2), 2-ethyl-3-methylpyrazine (3), 2-methylpyrazine (4), 2,5-dimethylpyrazine (5) and 2,6-dimethylpyrazine (6) (measured as sum 5/6), and 2,3-dimethylpyrazine (7), as well as 2,3,5-trimethylpyrazine (8)-varied in the range from +8.3 to -10.2 per thousand, thus revealing their biogeneration from amino acids (delta15N(AIR) ranging from +8 per thousand to -10 per thousand). The delta2H(VSMOW) values were determined in the range from -5 per thousand to -127 per thousand. Owing to the analytical differentiation observed between coffee alkylpyrazines and synthetic/"natural" samples of 3, 4, and 7, authenticity assessment of coffee-flavored products seems to be promising, provided that extended data will be available in the future. In the literature, there were no IRMS data available for the alkylpyrazines (1-8) under study.

  19. Delta Procalcitonin Is a Better Indicator of Infection Than Absolute Procalcitonin Values in Critically Ill Patients: A Prospective Observational Study

    Directory of Open Access Journals (Sweden)

    Domonkos Trásy

    2016-01-01

    Full Text Available Purpose. To investigate whether absolute value of procalcitonin (PCT or the change (delta-PCT is better indicator of infection in intensive care patients. Materials and Methods. Post hoc analysis of a prospective observational study. Patients with suspected new-onset infection were included in whom PCT, C-reactive protein (CRP, temperature, and leukocyte (WBC values were measured on inclusion (t0 and data were also available from the previous day (t-1. Based on clinical and microbiological data, patients were grouped post hoc into infection- (I- and noninfection- (NI- groups. Results. Of the 114 patients, 85 (75% had proven infection. PCT levels were similar at t-1: I-group (median [interquartile range]: 1.04 [0.40–3.57] versus NI-group: 0.53 [0.16–1.68], p=0.444. By t0 PCT levels were significantly higher in the I-group: 4.62 [1.91–12.62] versus 1.12 [0.30–1.66], p=0.018. The area under the curve to predict infection for absolute values of PCT was 0.64 [95% CI = 0.52–0.76], p=0.022; for percentage change: 0.77 [0.66–0.87], p<0.001; and for delta-PCT: 0.85 [0.78–0.92], p<0.001. The optimal cut-off value for delta-PCT to indicate infection was 0.76 ng/mL (sensitivity 80 [70–88]%, specificity 86 [68-96]%. Neither absolute values nor changes in CRP, temperature, or WBC could predict infection. Conclusions. Our results suggest that delta-PCT values are superior to absolute values in indicating infection in intensive care patients. This trial is registered with ClinicalTrials.gov identifier: NCT02311816.

  20. Synthesis of Gemcitabine-13C, 15N2 and Gemcitabine-13C, 15N2 Metabolites

    Directory of Open Access Journals (Sweden)

    ZHU Cheng-gu;YANG Shao-zu;YAN Sheng-wang;FANG Ning-jing;CAI Ding-long;LI Gang

    2014-02-01

    Full Text Available Homemade urea-13C, 15N2 was used to react with 3-methyl acrylonitrile closure to form cytosine-13C, 15N2 (2,which was protected by trimethylsilylation with BSA and condensed with 2-deoxy-2,2-difluoro-D-erythro-pentofuranose-3,5-dibenzoate-1-methanesulfonate at 120 ℃ to afford blocked gemcitabine-13C, 15N2. Hydrolytic removal of the blocking groups of gemcitabine-13C, 15N2 with NaOH gave gemcitabine-13C, 15N2, and its metabolite was obtained by further hydrolytic deamination of gemcitabine-13C, 15N2. The final products were characterized and detected by HPLC, LC-MS and NMR, and confirmed that the chemical purities were higher than 98%, isotopic abundances were 99% 13C, 98% 15N, and they were suitable for drug metabolism studies.

  1. Variable δ(15)N diet-tissue discrimination factors among sharks: implications for trophic position, diet and food web models.

    Science.gov (United States)

    Olin, Jill A; Hussey, Nigel E; Grgicak-Mannion, Alice; Fritts, Mark W; Wintner, Sabine P; Fisk, Aaron T

    2013-01-01

    The application of stable isotopes to characterize the complexities of a species foraging behavior and trophic relationships is dependent on assumptions of δ(15)N diet-tissue discrimination factors (∆(15)N). As ∆(15)N values have been experimentally shown to vary amongst consumers, tissues and diet composition, resolving appropriate species-specific ∆(15)N values can be complex. Given the logistical and ethical challenges of controlled feeding experiments for determining ∆(15)N values for large and/or endangered species, our objective was to conduct an assessment of a range of reported ∆(15)N values that can hypothetically serve as surrogates for describing the predator-prey relationships of four shark species that feed on prey from different trophic levels (i.e., different mean δ(15)N dietary values). Overall, the most suitable species-specific ∆(15)N values decreased with increasing dietary-δ(15)N values based on stable isotope Bayesian ellipse overlap estimates of shark and the principal prey functional groups contributing to the diet determined from stomach content analyses. Thus, a single ∆(15)N value was not supported for this speciose group of marine predatory fishes. For example, the ∆(15)N value of 3.7‰ provided the highest percent overlap between prey and predator isotope ellipses for the bonnethead shark (mean diet δ(15)N = 9‰) whereas a ∆(15)N value shark (mean diet δ(15)N = 15‰). These data corroborate the previously reported inverse ∆(15)N-dietary δ(15)N relationship when both isotope ellipses of principal prey functional groups and the broader identified diet of each species were considered supporting the adoption of different ∆(15)N values that reflect the predators' δ(15)N-dietary value. These findings are critical for refining the application of stable isotope modeling approaches as inferences regarding a species' ecological role in their community will be influenced with consequences for conservation and

  2. Rapid, storm-induced changes in the natural abundance of sup 15 N in a planktonic ecosystem, Chesapeake Bay, USA

    Energy Technology Data Exchange (ETDEWEB)

    Montoya, J.P.; McCarthy, J.J. (Harvard Univ., Cambridge, MA (United States)); Horrigan, S.G. (State Univ. of New York, Stony Brook (United States))

    1991-12-01

    Samples of dissolved inorganic nitrogen (DIN), particulate nitrogen (PN), and two species of zooplankton were collected during two north-south transects of the Chesapeake Bay in the autumn of 1984 (27-28 September and 3-5 October). During the first transect, the natural abundance of {sup 15}N ({delta} {sup 15}N) in the major dissolved and planktonic pools of nitrogen suggested that the {delta}{sup 15}N of PN was largely determined by isotopic fractionation during uptake of NH{sub 4}{sup +} by phytoplankton. Averaged over the transect as a whole, the {delta}{sup 15}N of the herbivorous calanoid copepod Acartia tonsa was 4.1% higher than that of the PN, while the {delta}{sup 15}N of the carnivorous ctenophore Mnemiopsis leidyi was 6.4% higher than that of the PN. In the interval between the two transects, storm-induced mixing of the water column resulted in the injection of NH{sub 4}{sup +} into the surface layer of the bay. In combination with ancillary physical, chemical, and biological data, these changes in {delta}{sup 15}N provided estimates of the isotopic fractionation factor for NH{sub 4}{sup +} uptake by phytoplankton ({alpha} = 1.0065-1.0080) as well as the turnover time of nitrogen in Acartia tonsa (6.0-9.6 days). Despite the changes in {delta}{sup 15}N observed during this cruise, the relative distribution of {sup 15}N between trophic levels was preserved: during the second transect, the difference in {delta}{sup 15}N between Acartia tonsa and PN was 3.6%, and the difference in {delta}{sup 15}N between Mnemiopsis leidyi and PN was 7.3%. These results demonstrate that the natural abundance of {sup 15}N can change dramatically on a time scale of days, and that time-series studies of the natural abundance of {sup 15}N can be a useful complement to studies using tracer additions of {sup 15}N to document nitrogen transformations in planktonic ecosystems.

  3. Atomic diffusion in metal poor stars. The influence on the Main Sequence fitting distance scale, subdwarfs ages and the value of Delta Y/ Delta Z

    Science.gov (United States)

    Salaris, M.; Groenewegen, M. A. T.; Weiss, A.

    2000-03-01

    , the age dispersion, the age-metallicity relation for Halo subdwarfs, as well as the value of the helium enrichment ratio Delta Y/Delta Z obtained from the width of the empirical Halo subdwarfs MS, are all significantly modified when the properly calibrated isochrones with diffusion are used.

  4. Ecosystem Service Value for the Common Reed Wetlands in the Liaohe Delta, Northeast China

    DEFF Research Database (Denmark)

    Ye, Siyuan; Laws, Edward A.; Costanza, Robert

    2016-01-01

    The largest reed field in the world, with an area of 1000 km2 in 1953, is located in the Liaohe Delta, which lies in the five-point-in-a-line economic strategic zone of northeastern China. However, the area of reeds has declined dramatically in recent years to accommodate oil field infrastructure...

  5. Spectral density function mapping using 15N relaxation data exclusively.

    Science.gov (United States)

    Farrow, N A; Zhang, O; Szabo, A; Torchia, D A; Kay, L E

    1995-09-01

    A method is presented for the determination of values of the spectral density function, J(omega), describing the dynamics of amide bond vectors from 15N relaxation parameters alone. Assuming that the spectral density is given by the sum of Lorentzian functions, the approach allows values of J(omega) to be obtained at omega = 0, omega N and 0.870 omega H, where omega N and omega H are Larmor frequencies of nitrogen and proton nuclei, respectively, from measurements of 15N T1, T2 and 1H-15N steady-state NOE values at a single spectrometer frequency. Alternatively, when measurements are performed at two different spectrometer frequencies of i and j MHz, J(omega) can be mapped at omega = 0, omega iN, omega jN, 0.870 omega iH and 0.870 omega iH, where omega iN, for example, is the 15N Larmor frequency for a spectrometer operating at 1 MHz. Additionally, measurements made at two different spectrometer frequencies enable contributions to transverse relaxation from motions on millisecond-microsecond time scales to be evaluated and permit assessment of whether a description of the internal dynamics is consistent with a correlation function consisting of a sum of exponentials. No assumptions about the specific form of the spectral density function describing the dynamics of the 15N-NH bond vector are necessary, provided that dJ(omega)/d omega is relatively constant between omega = omega H + omega N to omega = omega H - omega N. Simulations demonstrate that the method is accurate for a wide range of protein motions and correlation times, and experimental data establish the validity of the methodology. Results are presented for a folded and an unfolded form of the N-terminal SH3 domain of the protein drk.

  6. Nitrogen and 15N in the Mer Bleue peatland

    Science.gov (United States)

    Moore, Tim

    2017-04-01

    Although much of our attention in peatlands has focussed on carbon, as CO2, CH4 and DOC processing and fluxes, N plays an important role in the functioning of these ecosystems. Here, I present information on the distribution of N and 15N in plant and peat tissues and relate them to the cycling of N. N concentration in foliar tissues, ranged from 0.67 to 1.3% in evergreen shrubs and trees and mosses with little seasonal variation, and with a strong seasonal variation from 0.5 to 3.5% in the deciduous forbs, shrubs and trees, with a strong overall relationship to [chlorophyll]. Although the proportion of shrubs and mosses varied with microtopography the spatial foliar mass of N varied little with water table position, resulting in minor spatial variations in photosynthetic potential. Decomposition of plant tissues through litter to peat resulted in a decrease in the C:N ratio from about 50:1 to about 30:1 at the base of the profile, representing peat about 8000 yr old. This marginally larger loss of N through decomposition (mainly as TDN, 0.4 g N m-2 yr-1) compared to C produced a long-term N accumulation rate of 0.9 g N m-2 yr-1, being smaller in the bog phase, 0.6 N m-2 yr-1, and over past 150 yr, 0.8 g N m-2 yr-1. Although N is 'hard won' through N2 fixation, northern peatlands are significant global sinks of N and have limited N availability. del15N in foliar tissues ranged from -4 to -9 ‰ in evergreen and deciduous shrubs and trees, from -4 to -5 ‰ in mosses and from -1 to +1 ‰ in sedges and forbs. This appears to be a function of the mycorhizzal infection of the shrubs and trees, compared to sedges and forbs and the values for mosses may partially reflect the signature of atmospheric N deposition. There was no strong correlation between foliar [N] and del15N. In peat profiles from bog and fen sections of Mer Bleue, del15N values in peat fell from -5 to -2 ‰ in the top 10 cm to values of -1 to +1 ‰ at a depth of 40 cm and remained close to 0 ‰ below

  7. 15N fractionation in infrared-dark cloud cores

    Science.gov (United States)

    Zeng, S.; Jiménez-Serra, I.; Cosentino, G.; Viti, S.; Barnes, A. T.; Henshaw, J. D.; Caselli, P.; Fontani, F.; Hily-Blant, P.

    2017-07-01

    Context. Nitrogen is one of the most abundant elements in the Universe and its 14N/15N isotopic ratio has the potential to provide information about the initial environment in which our Sun formed. Recent findings suggest that the solar system may have formed in a massive cluster since the presence of short-lived radioisotopes in meteorites can only be explained by the influence of a supernova. Aims: We seek to determine the 14N/15N ratio towards a sample of cold and dense cores at the initial stages in their evolution. Methods: We observed the J = 1 → 0 transitions of HCN, H13CN, HC15N, HN13C, and H15NC towards a sample of 22 cores in four infrared-dark clouds (IRDCs) which are believed to be the precursors of high-mass stars and star clusters. Assuming LTE and a temperature of 15 K, the column densities of HCN, H13CN, HC15N, HN13C, and H15NC are calculated and their 14N/15N ratio is determined for each core. Results: The 14N/15N ratios measured in our sample of IRDC cores range between 70 and ≥763 in HCN and between 161 and 541 in HNC. These ratios are consistent with the terrestrial atmosphere (TA) and protosolar nebula (PSN) values, and with the ratios measured in low-mass prestellar cores. However, the 14N/15N ratios measured in cores C1, C3, F1, F2, and G2 do not agree with the results from similar studies towards the same cores using nitrogen bearing molecules with nitrile functional group (-CN) and nitrogen hydrides (-NH) although the ratio spread covers a similar range. Conclusions: Relatively low 14N/15N ratios amongst the four-IRDCs were measured in IRDC G which are comparable to those measured in small cosmomaterials and protoplanetary disks. The low average gas density of this cloud suggests that the gas density, rather than the gas temperature, may be the dominant parameter influencing the initial nitrogen isotopic composition in young PSN. The reduced spectra (FITS files) are only available at the CDS via anonymous ftp to http

  8. Compound-specific δ15N amino acid measurements in littoral mussels in the California upwelling ecosystem: a new approach to generating baseline δ15N Isoscapes for coastal ecosystems.

    Science.gov (United States)

    Vokhshoori, Natasha L; McCarthy, Matthew D

    2014-01-01

    We explored δ(15)N compound-specific amino acid isotope data (CSI-AA) in filter-feeding intertidal mussels (Mytilus californianus) as a new approach to construct integrated isoscapes of coastal primary production. We examined spatial δ(15)N gradients in the California Upwelling Ecosystem (CUE), determining bulk δ(15)N values of mussel tissue from 28 sites between Port Orford, Oregon and La Jolla, California, and applying CSI-AA at selected sites to decouple trophic effects from isotopic values at the base of the food web. Bulk δ(15)N values showed a strong linear trend with latitude, increasing from North to South (from ∼ 7‰ to ∼ 12‰, R(2) = 0.759). In contrast, CSI-AA trophic position estimates showed no correlation with latitude. The δ(15)N trend is therefore most consistent with a baseline δ(15)N gradient, likely due to the mixing of two source waters: low δ(15)N nitrate from the southward flowing surface California Current, and the northward transport of the California Undercurrent (CUC), with (15)N-enriched nitrate. This interpretation is strongly supported by a similar linear gradient in δ(15)N values of phenylalanine (δ(15)NPhe), the best AA proxy for baseline δ(15)N values. We hypothesize δ(15)N(Phe) values in intertidal mussels can approximate annual integrated δ(15)N values of coastal phytoplankton primary production. We therefore used δ(15)N(Phe) values to generate the first compound-specific nitrogen isoscape for the coastal Northeast Pacific, which indicates a remarkably linear gradient in coastal primary production δ(15)N values. We propose that δ(15)N(Phe) isoscapes derived from filter feeders can directly characterize baseline δ(15)N values across major biochemical provinces, with potential applications for understanding migratory and feeding patterns of top predators, monitoring effects of climate change, and study of paleo- archives.

  9. Compound-specific δ15N amino acid measurements in littoral mussels in the California upwelling ecosystem: a new approach to generating baseline δ15N Isoscapes for coastal ecosystems.

    Directory of Open Access Journals (Sweden)

    Natasha L Vokhshoori

    Full Text Available We explored δ(15N compound-specific amino acid isotope data (CSI-AA in filter-feeding intertidal mussels (Mytilus californianus as a new approach to construct integrated isoscapes of coastal primary production. We examined spatial δ(15N gradients in the California Upwelling Ecosystem (CUE, determining bulk δ(15N values of mussel tissue from 28 sites between Port Orford, Oregon and La Jolla, California, and applying CSI-AA at selected sites to decouple trophic effects from isotopic values at the base of the food web. Bulk δ(15N values showed a strong linear trend with latitude, increasing from North to South (from ∼ 7‰ to ∼ 12‰, R(2 = 0.759. In contrast, CSI-AA trophic position estimates showed no correlation with latitude. The δ(15N trend is therefore most consistent with a baseline δ(15N gradient, likely due to the mixing of two source waters: low δ(15N nitrate from the southward flowing surface California Current, and the northward transport of the California Undercurrent (CUC, with (15N-enriched nitrate. This interpretation is strongly supported by a similar linear gradient in δ(15N values of phenylalanine (δ(15NPhe, the best AA proxy for baseline δ(15N values. We hypothesize δ(15N(Phe values in intertidal mussels can approximate annual integrated δ(15N values of coastal phytoplankton primary production. We therefore used δ(15N(Phe values to generate the first compound-specific nitrogen isoscape for the coastal Northeast Pacific, which indicates a remarkably linear gradient in coastal primary production δ(15N values. We propose that δ(15N(Phe isoscapes derived from filter feeders can directly characterize baseline δ(15N values across major biochemical provinces, with potential applications for understanding migratory and feeding patterns of top predators, monitoring effects of climate change, and study of paleo- archives.

  10. Extreme value analysis of annual maximum water levels in the Pearl River Delta, China

    Institute of Scientific and Technical Information of China (English)

    Qiang ZHANG; Chong-Yu XU; Yongqin David CHEN; Chun-ling LIU

    2009-01-01

    We analyzed the statistical properties of water level extremes in the Pearl River Delta using five probability distribution functions. Estimation of para-meters was performed using the L-moment technique.Goodness-of-fit was done based on Kolmogorov-Smirnov's statistic D (K-S D). The research results indicate that Wakeby distribution is the best statistical model for description of statistical behaviors of water level extremes in the study region. Statistical analysis indicates that water levels corresponding to different return periods and associated variability tend to be larger in the landward side of the Pearl River Delta and vice versa. A ridge characterized by higher water level can be identified expanding along the West River and the Modaomen channel, showing the impacts of the hydrologic process of the West River basin. Trough and higher grades of water level changes can be detected in the region drained by Xi'nanyong channel, Dongping channel, and mainstream of Pearl River. The Pearl River Delta region is character-ized by low-lying topography and a highly-advanced socio-economy, and is heavily populated, being prone to flood hazards and flood inundation due to rising sea level and typhoons. Therefore, sound and effective counter-measures should be made for human mitigation to natural hazards such as floods and typhoons.

  11. Incorporation of Socio-Cultural Values in Damage Assessment Valuations of Contaminated Lands in the Niger Delta

    Directory of Open Access Journals (Sweden)

    Victor A. Akujuru

    2014-07-01

    Full Text Available Damages on contaminated land have been mostly assessed for developments subsisting on the land, neglecting the goods and services derived from the land which possess only socio-cultural values. This paper aims to ascertain the importance of socio-cultural values in the total economic value of contaminated land, drawing from the experience of a coastal community oil spillage in the Niger Delta. The paper examines what constitutes a valuable interest on contaminated land and how socio-cultural factors are valued in the damage assessment process. After reviewing the literature and decided cases, a questionnaire survey was conducted and a sample valuation report was analysed. It is concluded that there exists a socio-cultural interest on contaminated land which professional valuers do not reflect in damage assessment claims. It is recommended that any comprehensive damage assessment requires the incorporation of socio-cultural values in the valuations.

  12. Determination of the δ15N of nitrate in solids; RSIL lab code 2894

    Science.gov (United States)

    Coplen, Tyler B.; Qi, Haiping; Revesz, Kinga; Casciotti, Karen; Hannon, Janet E.

    2007-01-01

    The purpose of the Reston Stable Isotope Laboratory (RSIL) lab code 2894 is to determine the δ15N of nitrate (NO3-) in solids. The nitrate fraction of the nitrogen species is dissolved by water (called leaching) and can be analyzed by the bacterial method covered in RSIL lab code 2899. After leaching, the δ15N of the dissolved NO3- is analyzed by conversion of the NO3- to nitrous oxide (N2O), which serves as the analyte for mass spectrometry. A culture of denitrifying bacteria is used in the enzymatic conversion of NO3- to N2O, which follows the pathway shown in equation 1: NO3- → NO2- → NO → 1/2 N2O (1) Because the bacteria Pseudomonas aureofaciens lack N2O reductive activity, the reaction stops at N2O, unlike the typical denitrification reaction that goes to N2. After several hours, the conversion is complete, and the N2O is extracted from the vial, separated from volatile organic vapor and water vapor by an automated -65 °C isopropanol-slush trap, a Nafion drier, a CO2 and water removal unit (Costech #021020 carbon dioxide absorbent with Mg(ClO4)2), and trapped in a small-volume trap immersed in liquid nitrogen with a modified Finnigan MAT (now Thermo Scientific) GasBench 2 introduction system. After the N2O is released, it is further purified by gas chromatography before introduction to the isotope-ratio mass spectrometer (IRMS). The IRMS is a Thermo Scientific Delta V Plus continuous flow IRMS (CF-IRMS). It has a universal triple collector, consisting of two wide cups with a narrow cup in the middle; it is capable of simultaneously measuring mass/charge (m/z) of the N2O molecule 44, 45, and 46. The ion beams from these m/z values are as follows: m/z = 44 = N2O = 14N14N16O; m/z = 45 = N2O = 14N15N16O or 14N14N17O; m/z = 46 = N2O = 14N14N18O. The 17O contributions to the m/z 44 and m/z 45 ion beams are accounted for before δ15N values are reported.

  13. Determination of the δ15N of nitrate in water; RSIL lab code 2899

    Science.gov (United States)

    Coplen, Tyler B.; Qi, Haiping; Revesz, Kinga; Casciotti, Karen; Hannon, Janet E.

    2007-01-01

    The purpose of the Reston Stable Isotope Laboratory (RSIL) lab code 2899 is to determine the δ15N of nitrate (NO3-) in water. The δ15N of the dissolved NO3- is analyzed by conversion of the NO3- to nitrous oxide (N2O), which serves as the analyte for mass spectrometry. A culture of denitrifying bacteria is used in the enzymatic conversion of the NO3- to N2O, which follows the pathway shown in equation 1: NO3- → NO2- → NO → 1/2 N2O (1) Because the bacteria Pseudomonas aureofaciens lack N2O reductive activity, the reaction stops at N2O, unlike the typical denitrification reaction that goes to N2. After several hours, the conversion is complete, and the N2O is extracted from the vial, separated from volatile organic vapor and water vapor by an automated -65 °C isopropanol-slush trap, a Nafion drier, a CO2 and water removal unit (Costech #021020 carbon dioxide absorbent with Mg(ClO4)2), and trapped in a small-volume trap immersed in liquid nitrogen with a modified Finnigan MAT (now Thermo Scientific) GasBench 2 introduction system. After the N2O is released, it is further purified by gas chromatography before introduction to the isotope-ratio mass spectrometer (IRMS). The IRMS is a Thermo Scientific Delta V Plus continuous flow IRMS (CF-IRMS). It has a universal triple collector, consisting of two wide cups with a narrow cup in the middle; it is capable of simultaneously measuring mass/charge (m/z) of the N2O molecule 44, 45, and 46. The ion beams from these m/z values are as follows: m/z = 44 = N2O = 14N14N16O; m/z = 45 = N2O = 14N15N16O or 14N14N17O; m/z = 46 = N2O = 14N14N18O. The 17O contributions to the m/z 44 and m/z 45 ion beams are accounted for before δ15N values are reported.

  14. Human dietary δ(15)N intake: representative data for principle food items.

    Science.gov (United States)

    Huelsemann, F; Koehler, K; Braun, H; Schaenzer, W; Flenker, U

    2013-09-01

    Dietary analysis using δ(15)N values of human remains such as bone and hair is usually based on general principles and limited data sets. Even for modern humans, the direct ascertainment of dietary δ(15)N is difficult and laborious, due to the complexity of metabolism and nitrogen fractionation, differing dietary habits and variation of δ(15)N values of food items. The objective of this study was to summarize contemporary regional experimental and global literature data to ascertain mean representative δ(15)N values for distinct food categories. A comprehensive data set of more than 12,000 analyzed food samples was summarized from the literature. Data originated from studies dealing with (1) authenticity tracing or origin control of food items, and (2) effects of fertilization or nutrition on δ(15)N values of plants or animals. Regional German food δ(15)N values revealed no major differences compared with the mean global values derived from the literature. We found that, in contrast to other food categories, historical faunal remains of pig and poultry are significantly enriched in (15)N compared to modern samples. This difference may be due to modern industrialized breeding practices. In some food categories variations in agricultural and feeding regimens cause significant differences in δ(15)N values that may lead to misinterpretations when only limited information is available.

  15. Development of Evaluation Models for Estimation of Economic Values of Natural Gas Fractionation in the Niger Delta

    Directory of Open Access Journals (Sweden)

    Udie, A. C.

    2016-06-01

    Full Text Available Natural gas fractionation components and economic values models have been developed in the Niger Delta. The importance is to enhance diversifying utilization, reduce gas flaring, creates fast development, impacts on building the Nation’s economy, industrialization and jobs creation in the country. This was possible calculated average Natural gas values, weight, heating value, specific gravity and ratio of the gas components (LNG, LPG and condensate. The resulted fractionation ratio is 85.76% of LNG, 11.61% of LPG and 2.28% of condensate (liquid with a revenue generation of LNG USD1.85/SCF, LPG N 0.41/SCF and N 0.38/SCF. The revenue per give time depends on demand and supply.

  16. Disturbance and topography shape nitrogen availability and δ15N over long-term forest succession

    Science.gov (United States)

    Forest disturbance and long-term succession can promote open N cycling that increases N loss and soil δ15N values. We examined soil and foliar patterns in N and δ15N, and soil N mineralization, across a topographically complex montane forest landscape influenced by human logging ...

  17. 1H, 13C, 15N and 195Pt NMR studies of Au(III) and Pt(II) chloride organometallics with 2-phenylpyridine.

    Science.gov (United States)

    Pazderski, Leszek; Pawlak, Tomasz; Sitkowski, Jerzy; Kozerski, Lech; Szłyk, Edward

    2009-11-01

    (1)H, (13)C, (15)N and (195)Pt NMR studies of gold(III) and platinum(II) chloride organometallics with N(1),C(2')-chelated, deprotonated 2-phenylpyridine (2ppy*) of the formulae [Au(2ppy*)Cl(2)], trans(N,N)-[Pt(2ppy*)(2ppy)Cl] and trans(S,N)-[Pt(2ppy*)(DMSO-d(6))Cl] (formed in situ upon dissolving [Pt(2ppy*)(micro-Cl)](2) in DMSO-d(6)) were performed. All signals were unambiguously assigned by HMBC/HSQC methods and the respective (1)H, (13)C and (15)N coordination shifts (i.e. differences between chemical shifts of the same atom in the complex and ligand molecules: Delta(1H)(coord) = delta(1H)(complex) - delta(1H)(ligand), Delta(13C)(coord) = delta(13C)(complex) - delta(13C)(ligand), Delta(15N)(coord) = delta(15N)(complex) - delta(15N)(ligand)), as well as (195)Pt chemical shifts and (1)H-(195)Pt coupling constants discussed in relation to the known molecular structures. Characteristic deshielding of nitrogen-adjacent H(6) protons and metallated C(2') atoms as well as significant shielding of coordinated N(1) nitrogens is discussed in respect to a large set of literature NMR data available for related cyclometallated compounds.

  18. Macroalgae delta N-15 values in well-mixed estuaries: Indicator of anthropogenic nitrogen input or macroalgae metabolism?

    OpenAIRE

    Raimonet, Melanie; Guillou, Gael; Mornet, Francoise; Richard, Pierre

    2013-01-01

    Although nitrogen stable isotope ratio (delta N-15) in macroalgae is widely used as a bioindicator of anthropogenic nitrogen inputs to the coastal zone, recent studies suggest the possible role of macroalgae metabolism in delta N-15 variability. Simultaneous determinations of delta N-15 of dissolved inorganic nitrogen (DIN) along the land sea continuum, inter-species variability of delta N-15 and its sensitivity to environmental factors are necessary to confirm the efficiency of macroalgae de...

  19. Binding of thiocyanate to lactoperoxidase: 1H and 15N nuclear magnetic resonance studies

    Energy Technology Data Exchange (ETDEWEB)

    Modi, S.; Behere, D.V.; Mitra, S. (Tata Institute of Fundamental Research, Bombay (India))

    1989-05-30

    The binding of thiocyanate to lactoperoxidase (LPO) has been investigated by 1H and 15N NMR spectroscopy. 1H NMR of LPO shows that the major broad heme methyl proton resonance at about 61 ppm is shifted upfield by addition of the thiocyanate, indicating binding of the thiocyanate to the enzyme. The pH dependence of line width of 15N resonance of SC15N- in the presence of the enzyme has revealed that the binding of the thiocyanate to the enzyme is facilitated by protonation of an ionizable group (with pKa of 6.4), which is presumably distal histidine. Dissociation constants (KD) of SC15N-/LPO, SC15N-/LPO/I-, and SC15N-/LPO/CN- equilibria have been determined by 15N T1 measurements and found to be 90 +/- 5, 173 +/- 20, and 83 +/- 6 mM, respectively. On the basis of these values of KD, it is suggested that the iodide ion inhibits the binding of the thiocyanate but cyanide ion does not. The thiocyanate is shown to bind at the same site of LPO as iodide does, but the binding is considerably weaker and is away from the ferric ion. The distance of 15N of the bound thiocyanate ion from the iron is determined to be 7.2 +/- 0.2 A from the 15N T1 measurements.

  20. {sup 37}Cl, {sup 15}N, {sup 13}C isotopic analysis of common agro-chemicals for identifying non-point source agricultural contaminants

    Energy Technology Data Exchange (ETDEWEB)

    Annable, W.K. [Department of Civil and Environmental Engineering, University of Waterloo, Waterloo, Ontario, N2L 3G1 (Canada)]. E-mail: wkannabl@uwaterloo.ca; Frape, S.K. [Department of Earth Sciences, University of Waterloo, Waterloo, Ontario, N2L 3G1 (Canada); Shouakar-Stash, O. [Department of Earth Sciences, University of Waterloo, Waterloo, Ontario, N2L 3G1 (Canada); Shanoff, T. [Department of Earth Sciences, University of Waterloo, Waterloo, Ontario, N2L 3G1 (Canada); Drimmie, R.J. [Department of Earth Sciences, University of Waterloo, Waterloo, Ontario, N2L 3G1 (Canada); Harvey, F.E. [School of Natural Resources, University of Nebraska, Lincoln, NE 68588-0517 (United States)

    2007-07-15

    The isotopic compositions of commercially available herbicides were analyzed to determine their respective {sup 15}N, {sup 13}C and {sup 37}Cl signatures for the purposes of developing a discrete tool for tracing and identifying non-point source contaminants in agricultural watersheds. Findings demonstrate that of the agrochemicals evaluated, chlorine stable isotopes signatures range between {delta}{sup 37}Cl = -4.55 per mille and +3.40 per mille , whereas most naturally occurring chlorine stable isotopes signatures, including those of road salt, sewage sludge and fertilizers, vary in a narrow range about the Standard Mean Ocean Chloride (SMOC) between -2.00 per mille and +1.00 per mille . Nitrogen stable isotope values varied widely from {delta}{sup 15}N = -10.86 per mille to +1.44 per mille and carbon stable isotope analysis gave an observed range between {delta}{sup 13}C = -37.13 per mille and -21.35 per mille for the entire suite of agro-chemicals analyzed. When nitrogen, carbon and chlorine stable isotope analyses were compared in a cross-correlation analysis, statistically independent isotopic signatures exist suggesting a new potential tracer tool for identifying herbicides in the environment.

  1. δ(15) N from soil to wine in bulk samples and proline.

    Science.gov (United States)

    Paolini, Mauro; Ziller, Luca; Bertoldi, Daniela; Bontempo, Luana; Larcher, Roberto; Nicolini, Giorgio; Camin, Federica

    2016-09-01

    The feasibility of using δ(15) N as an additional isotopic marker able to link wine to its area of origin was investigated. The whole production chain (soil-leaves-grape-wine) was considered. Moreover, the research included evaluation of the effect of the fermentation process, the use of different types of yeast and white and red vinification, the addition of nitrogen adjuvants and ultrasound lysis simulating wine ageing. The δ(15) N of grapes and wine was measured in bulk samples and compounds, specifically in proline, for the first time. Despite isotopic fractionation from soil to wine, the δ(15) N values of leaves, grapes, wine and particularly must and wine proline conserved the variability of δ(15) N in the growing soil. Fermentation and ultrasound treatment did not affect the δ(15) N values of grape must, which was therefore conserved in wine. The addition of inorganic or organic adjuvants was able to influence the δ(15) N of bulk wine, depending on the amount and the difference between the δ(15) N of must and that of the adjuvant. The δ(15) N of wine proline was not influenced by adjuvant addition and is therefore the best marker for tracing the geographical origin of wine. Copyright © 2016 John Wiley & Sons, Ltd.

  2. Variable δ(15N diet-tissue discrimination factors among sharks: implications for trophic position, diet and food web models.

    Directory of Open Access Journals (Sweden)

    Jill A Olin

    Full Text Available The application of stable isotopes to characterize the complexities of a species foraging behavior and trophic relationships is dependent on assumptions of δ(15N diet-tissue discrimination factors (∆(15N. As ∆(15N values have been experimentally shown to vary amongst consumers, tissues and diet composition, resolving appropriate species-specific ∆(15N values can be complex. Given the logistical and ethical challenges of controlled feeding experiments for determining ∆(15N values for large and/or endangered species, our objective was to conduct an assessment of a range of reported ∆(15N values that can hypothetically serve as surrogates for describing the predator-prey relationships of four shark species that feed on prey from different trophic levels (i.e., different mean δ(15N dietary values. Overall, the most suitable species-specific ∆(15N values decreased with increasing dietary-δ(15N values based on stable isotope Bayesian ellipse overlap estimates of shark and the principal prey functional groups contributing to the diet determined from stomach content analyses. Thus, a single ∆(15N value was not supported for this speciose group of marine predatory fishes. For example, the ∆(15N value of 3.7‰ provided the highest percent overlap between prey and predator isotope ellipses for the bonnethead shark (mean diet δ(15N = 9‰ whereas a ∆(15N value < 2.3‰ provided the highest percent overlap between prey and predator isotope ellipses for the white shark (mean diet δ(15N = 15‰. These data corroborate the previously reported inverse ∆(15N-dietary δ(15N relationship when both isotope ellipses of principal prey functional groups and the broader identified diet of each species were considered supporting the adoption of different ∆(15N values that reflect the predators' δ(15N-dietary value. These findings are critical for refining the application of stable isotope modeling approaches as inferences regarding a species

  3. Nitrogen cycling in an extreme hyperarid environment inferred from δ(15)N analyses of plants, soils and herbivore diet.

    Science.gov (United States)

    Díaz, Francisca P; Frugone, Matías; Gutiérrez, Rodrigo A; Latorre, Claudio

    2016-03-09

    Climate controls on the nitrogen cycle are suggested by the negative correlation between precipitation and δ(15)N values across different ecosystems. For arid ecosystems this is unclear, as water limitation among other factors can confound this relationship. We measured herbivore feces, foliar and soil δ(15)N and δ(13)C values and chemically characterized soils (pH and elemental composition) along an elevational/climatic gradient in the Atacama Desert, northern Chile. Although very positive δ(15)N values span the entire gradient, soil δ(15)N values show a positive correlation with aridity as expected. In contrast, foliar δ(15)N values and herbivore feces show a hump-shaped relationship with elevation, suggesting that plants are using a different N source, possibly of biotic origin. Thus at the extreme limits of plant life, biotic interactions may be just as important as abiotic processes, such as climate in explaining ecosystem δ(15)N values.

  4. Nitrogen cycling in an extreme hyperarid environment inferred from δ15N analyses of plants, soils and herbivore diet

    Science.gov (United States)

    Díaz, Francisca P.; Frugone, Matías; Gutiérrez, Rodrigo A.; Latorre, Claudio

    2016-03-01

    Climate controls on the nitrogen cycle are suggested by the negative correlation between precipitation and δ15N values across different ecosystems. For arid ecosystems this is unclear, as water limitation among other factors can confound this relationship. We measured herbivore feces, foliar and soil δ15N and δ13C values and chemically characterized soils (pH and elemental composition) along an elevational/climatic gradient in the Atacama Desert, northern Chile. Although very positive δ15N values span the entire gradient, soil δ15N values show a positive correlation with aridity as expected. In contrast, foliar δ15N values and herbivore feces show a hump-shaped relationship with elevation, suggesting that plants are using a different N source, possibly of biotic origin. Thus at the extreme limits of plant life, biotic interactions may be just as important as abiotic processes, such as climate in explaining ecosystem δ15N values.

  5. A Critical Analysis of Climate Change Factors and its Projected Future Values in Delta State, Nigeria

    Directory of Open Access Journals (Sweden)

    Emaziye, P. O., R. N. Okoh

    2012-06-01

    Full Text Available The study focused on the critical analysis of climate change factors (temperature and rainfall and its projected future values in the state. The main objective was to determine the trends of climate change factors (temperature and rainfall. And the specific objective was to determine the projected future trends of climate change factors in the state. Multistage sampling procedure was used in the random selection of states, local government, communities and rural households for the research study. Annual mean time series data of temperature and rainfall were collected from Nigerian Meteorological Agency (NIMET. Data were also obtained from structure questionnaire survey. The collected data were analyzed using descriptive statistics, trend analysis and growth model. The study reveals that there were increasing trends of temperature values and decreasing rainfall values in the state. But their projected future values witnessed an increasing trend. The increasing trends in temperature values may lead to a situation were crops will be smothered by excessive heat thereby reducing food production in the state. The study therefore recommends that meteorological station units should be established in the rural farming households in the state where accessibility is extremely difficult. This will make available meteorological data (information to the reach of the poor rural farming household for the attainment of food production.

  6. Factors Controlling the Stable Nitrogen Isotopic Composition (δ15N of Lipids in Marine Animals.

    Directory of Open Access Journals (Sweden)

    Elisabeth Svensson

    Full Text Available Lipid extraction of biomass prior to stable isotope analysis is known to cause variable changes in the stable nitrogen isotopic composition (δ15N of residual biomass. However, the underlying factors causing these changes are not yet clear. Here we address this issue by comparing the δ15N of bulk and residual biomass of several marine animal tissues (fish, crab, cockle, oyster, and polychaete, as well as the δ15N of the extracted lipids. As observed previously, lipid extraction led to a variable offset in δ15N of biomass (differences ranging from -2.3 to +1.8 ‰. Importantly, the total lipid extract (TLE was highly depleted in 15N compared to bulk biomass, and also highly variable (differences ranging from -14 to +0.7 ‰. The TLE consisted mainly of phosphatidylcholines, a group of lipids with one nitrogen atom in the headgroup. To elucidate the cause for the 15N-depletion in the TLE, the δ15N of amino acids was determined, including serine because it is one of the main sources of nitrogen to N-containing lipids. Serine δ15N values differed by -7 to +2 ‰ from bulk biomass δ15N, and correlated well with the 15N depletion in TLEs. On average, serine was less depleted (-3‰ than the TLE (-7 ‰, possibly due to fractionation during biosynthesis of N-containing headgroups, or that other nitrogen-containing compounds, such as urea and choline, or recycled nitrogen contribute to the nitrogen isotopic composition of the TLE. The depletion in 15N of the TLE relative to biomass increased with the trophic level of the organisms.

  7. Synthesis of {sup 15}N labeled glyphosate; Sintese do glifosato enriquecido com {sup 15}N

    Energy Technology Data Exchange (ETDEWEB)

    Oliveira, Claudineia R. de; Bendassolli, Jose Albertino; Tavares, Glauco Arnold; Rossete, Alexssandra L.R.M.; Tagliassachi, Romulo Barbieri; Prestes, Cleuber Vieira [Centro de Energia Nuclear na Agricultura (CENA), Piracicaba, SP (Brazil). Dept. de Isotopos Estaveis]. E-mail: crolivei@cena.usp.br

    2005-07-01

    Amongst the actually commercialized herbicides the Glyphosate is the most used in Brazil. Its efficiency as well as the others herbicides against undesirable weeds is harmed by its final composts left at the environment. Although studies has being carried out to improve the knowledge about the herbicides behavior at the environment its complexity has led them towards innumerous to new significant research work where the use of radiolabeled composts (radiative tracers) are recommended to evaluate their bio-availability in the soil. However is the use, the manipulation and the storage of radiolabeled composts is requires an extra care under chemical safety point of view. The use of non radiolabeled composts is a world tendency especially for field researches. Under this context the presented work describes a method for the synthesis of {sup 15}N labeled glyphosate. The {sup 15}N-herbicide was undertaken by phosphometilation with the phosphit dialquil and {sup 15}N-glycine. The tests where carried out through a micro scale production plant and of equimolars amounts. At these conditions it's was possible to reach approximately a 20% of yield. At the conclusion of a best operational condition its expected to offer another important toll that shall be used in glyphosate behavior at the environment and undesirably weeds. (author)

  8. Delta13C values of grasses as a novel indicator of pollution by fossil-fuel-derived greenhouse gas CO2 in urban areas.

    Science.gov (United States)

    Lichtfouse, Eric; Lichtfouse, Michel; Jaffrézic, Anne

    2003-01-01

    A novel fossil fuel pollution indicator based on the 13C/12C isotopic composition of plants has been designed. This bioindicator is a promising tool for future mapping of the sequestration of fossil fuel CO2 into urban vegetation. Theoretically, plants growing in fossil-fuel-CO2-contaminated areas, such as major cities, industrial centers, and highway borders, should assimilate a mixture of global atmospheric CO2 of delta13C value of -8.02 per thousand and of fossil fuel CO2 of average delta13C value of -27.28 per thousand. This isotopic difference should, thus, be recorded in plant carbon. Indeed, this study reveals that grasses growing near a major highway in Paris, France, have strikingly depleted delta13C values, averaging at -35.08 per thousand, versus rural grasses that show an average delta13C value of -30.59 per thousand. A simple mixing model was used to calculate the contributions of fossil-fuel-derived CO2 to the plant tissue. Calculation based on contaminated and noncontaminated isotopic end members shows that urban grasses assimilate up to 29.1% of fossil-fuel-CO2-derived carbon in their tissues. The 13C isotopic composition of grasses thus represents a promising new tool for the study of the impact of fossil fuel CO2 in major cities.

  9. Understanding the Value of Satellite Altimetry for Monitoring Water Level Dynamics of Large Rivers in Bangladesh Delta

    Science.gov (United States)

    Hossain, F.; Akbor, S.; Sustainability, Satellites, Water; Environment (Saswe) Research Group

    2010-12-01

    Although transboundary river flow accounts for more than 40% of global surface flow across 145 nations (many of them water-stressed and conflict-prone), most of this flow is difficult to monitor in developing nations at operational timescales. For Bangladesh, this situation is particularly acute because it comprises only 7% of the entire Ganges-Brahmaputra-Meghna basin and is located at the downstream end of the basin. Thus more than 90% of the water is generated in upstream nations and yet this information is hard to obtain in Bangladesh due to lack of transboundary instrumentation or international treaties. This work therefore investigates the value of satellite radar altimetry in detecting the water level changes for large rivers in the Bangladesh Delta. It is founded on the hypothesis that a satellite altimeter can detect water level to the same accuracy for both inside and outside of Bangladesh. First, the river hydraulic model called HEC-RAS (Hydrologic Engineering Center, River Analysis System) is set up and calibrated over Bangladesh using a comprehensive database on in-situ river bathymetry and observed water level records. Next, the calibrated HEC-RAS model is provided boundary flow conditions upstream and downstream of the model domain. At the upstream end where the Ganges, Brahmaputra and Meghan enter Bangladesh, high resolution flow data modeled from a well calibrated hydrologic model called MIKE BASIN is provided as input. The observed tidal flow records of the Meghna estuary near the Bay of Bengal are used as the downstream boundary conditions. HEC-RAS is then used to simulate daily water level data for the period of 2003-2005 for major rivers of Bangladesh. These water level simulations are directly compared with altimeter estimates of water level from the ENVISAT mission. Accuracy of ENVISAT data is characterized as a function of season, flow regime and river type. The important question that this study aims to answer is, “To what extent can

  10. 15N Content Reflects Development of Mycorrhizae and Nitrogen Dynamics During Primary Succession

    Science.gov (United States)

    Hobbie, E. A.; Jumpponen, A.

    2004-05-01

    Mycorrhizal fungi are ubiquitous symbionts on terrestrial plants that are particularly important for plant nitrogen nutrition. 15N content appears to be a useful marker of the mycorrhizal role in plant nitrogen supply because of an apparent fractionation against 15N during transfer of nitrogen from mycorrhizal fungi to host plants. Because plants developing during primary succession are gradually colonized by mycorrhizal fungi, such situations provide good opportunities to study interactions between mycorrhizal colonization and plant 15N content. Here, we present results of a study of nitrogen isotope patterns in ecosystem components during the first 100 years of ecosystem development after glacial retreat, and compare those patterns with those on adjacent mature terrain. Soils in primary succession were depleted in 15N relative to nitrogen-fixing plants. Nonmycorrhizal plants and plants generally colonized by ectomycorrhizal, ericoid, or arbuscular fungi showed similar 15N content very early in succession (-4 to -6‰ ), corresponding to low colonization levels of all plant species. Subsequent colonization of evergreen plants by ectomycorrhizal and ericoid fungi led to a 5-6‰ decline in 15N content, indicating transfer of 15N-depleted N from fungi to plants. The values recorded (-10 to -14‰ ) are among the lowest yet observed in vascular plants. Nonmycorrhizal plants and plants colonized by arbuscular mycorrhizal fungi did not decline in 15N content. Most ectomycorrhizal and saprotrophic fungi were similar in 15N content in early succession (-1 to -3‰ ), with the notable exception of ectomycorrhizal fungi suspected of proteolytic capabilities, which were 15N enriched relative to all other fungi. 15N contents in both plants and soil from the mature site were 5‰ greater than in recently exposed sites. We conclude that 1) the primary nitrogen source to this ecosystem must be atmospheric deposition, 2) low plant 15N content generally corresponds with greater

  11. Determination of the δ15N and δ18O of nitrate in water; RSIL lab code 2900

    Science.gov (United States)

    Coplen, Tyler B.; Qi, Haiping; Revesz, Kinga; Casciotti, Karen; Hannon, Janet E.

    2007-01-01

    The purpose of the Reston Stable Isotope Laboratory (RSIL) lab code 2900 is to determine the δ15N and δ18O of nitrate (NO3-) in water. The δ15N and δ18O of the dissolved NO3- are analyzed by converting the NO3- to nitrous oxide (N2O), which serves as the analyte for mass spectrometry. A culture of denitrifying bacteria is used in the enzymatic conversion of the NO3- to N2O, which follows the pathway shown in equation 1: NO3- → NO2- → NO → 1/2 N2O (1) Because the bacteria Pseudomonas aureofaciens lack N2O reductive activity, the reaction stops at N2O, unlike the typical denitrification reaction that goes to N2. After several hours, the conversion is complete, and the N2O is extracted from the vial, separated from volatile organic vapor and water vapor by an automated -65 °C isopropanol-slush trap, a Nafion drier, a CO2 and water removal unit (Costech #021020 carbon dioxide absorbent with Mg(ClO4)2), and trapped in a small-volume trap immersed in liquid nitrogen with a modified Finnigan MAT (now Thermo Scientific) GasBench 2 introduction system. After the N2O is released, it is further purified by gas chromatography before introduction to the isotope-ratio mass spectrometer (IRMS). The IRMS is a Thermo Scientific Delta V Plus continuous flow IRMS (CF-IRMS). It has a universal triple collector, consisting of two wide cups with a narrow cup in the middle; it is capable of simultaneously measuring mass/charge (m/z) of the N2O molecule 44, 45, and 46. The ion beams from these m/z values are as follows: m/z = 44 = N2O = 14N14N16O; m/z = 45 = N2O = 14N15N16O or 14N14N17O; m/z = 46 = N2O = 14N14N18O. The 17O contributions to the m/z 44 and m/z 45 ion beams are accounted for before δ15N values are reported.

  12. Determination of the δ15N and δ18O of nitrate in solids; RSIL lab code 2897

    Science.gov (United States)

    Coplen, Tyler B.; Qi, Haiping; Revesz, Kinga; Casciotti, Karen; Hannon, Janet E.

    2007-01-01

    The purpose of the Reston Stable Isotope Laboratory (RSIL) lab code 2897 is to determine the δ15N and δ18O of nitrate (NO3-) in solids. The NO3- fraction of the nitrogen species is dissolved by water (called leaching) and can be analyzed by the bacterial method covered in RSIL lab code 2900. After leaching, the δ15N and δ18O of the dissolved NO3- is analyzed by conversion of the NO3- to nitrous oxide (N2O), which serves as the analyte for mass spectrometry. A culture of denitrifying bacteria is used in the enzymatic conversion of NO3- to N2O, which follows the pathway shown in equation 1: NO3- → NO2- → NO → 1/2 N2O (1) Because the bacteria Pseudomonas aureofaciens lack N2O reductive activity, the reaction stops at N2O, unlike the typical denitrification reaction that goes to N2. After several hours, the conversion is complete, and the N2O is extracted from the vial, separated from volatile organic vapor and water vapor by an automated -65 °C isopropanol-slush trap, a Nafion drier, a CO2 and water removal unit (Costech #021020 carbon dioxide absorbent with Mg(ClO4)2), and trapped in a small-volume trap immersed in liquid nitrogen with a modified Finnigan MAT (now Thermo Scientific) GasBench 2 introduction system. After the N2O is released, it is further purified by gas chromatography before introduction to the isotope-ratio mass spectrometer (IRMS). The IRMS is a Thermo Scientific Delta V Plus continuous flow IRMS (CF-IRMS). It has a universal triple collector, consisting of two wide cups with a narrow cup in the middle; it is capable of simultaneously measuring mass/charge (m/z) of the N2O molecule 44, 45, and 46. The ion beams from these m/z values are as follows: m/z = 44 = N2O = 14N14N16O; m/z = 45 = N2O = 14N15N16O or 14N14N17O; m/z = 46 = N2O = 14N14N18O. The 17O contributions to the m/z 44 and m/z 45 ion beams are accounted for before δ15N values are reported.

  13. Nitrogen content, {sup 15}N natural abundance and biomass of the two pleurocarpous mosses Pleurozium schreberi (Brid.) Mitt. and Scleropodium purum (Hedw.) Limpr. in relation to atmospheric nitrogen deposition

    Energy Technology Data Exchange (ETDEWEB)

    Solga, A. [Nees-Institute for Biodiversity of Plants, University of Bonn, Meckenheimer Allee 170, D-53115 Bonn (Germany)]. E-mail: a.solga@uni-bonn.de; Burkhardt, J. [Institute of Plant Nutrition, University of Bonn, Karlrobert-Kreiten-Strasse 13, D-53115 Bonn (Germany); Zechmeister, H.G. [Institute of Ecology and Conservation Biology, University of Vienna, Althanstrasse 14, A-1091 Vienna (Austria); Frahm, J.-P. [Nees-Institute for Biodiversity of Plants, University of Bonn, Meckenheimer Allee 170, D-53115 Bonn (Germany)

    2005-04-01

    The suitability of the two pleurocarpous mosses Pleurozium schreberi and Scleropodium purum for assessing spatial variation in nitrogen deposition was investigated. Sampling was carried out at eight sites in the western part of Germany with bulk deposition rates ranging between 6.5 and 18.5 kg N ha{sup -1} yr{sup -1}. In addition to the effect of deposition on the nitrogen content of the two species, its influence on {sup 15}N natural abundance ({delta}{sup 15}N values) and on productivity was examined. Annual increases of the mosses were used for all analyses. Significant relationships between bulk N deposition and nitrogen content were obtained for both species; {delta}{sup 15}N-values reflected the ratio of NH{sub 4}-N to NO{sub 3}-N in deposition. A negative effect of nitrogen input on productivity, i.e. decreasing biomass per area with increasing N deposition due to a reduction of stem density, was particularly evident with P. schreberi. Monitoring of N deposition by means of mosses is considered an important supplement to existing monitoring programs. It makes possible an improved spatial resolution, and thus those areas that receive high loads of nitrogen are more easily discernible. - Mosses are useful as monitors of nitrogen deposition.

  14. (13)C, (15)N CPMAS NMR and GIAO DFT calculations of stereoisomeric oxindole alkaloids from Cat's Claw (Uncaria tomentosa).

    Science.gov (United States)

    Paradowska, Katarzyna; Wolniak, Michał; Pisklak, Maciej; Gliński, Jan A; Davey, Matthew H; Wawer, Iwona

    2008-11-01

    Oxindole alkaloids, isolated from the bark of Uncaria tomentosa [Willd. ex Schult.] Rubiaceae, are considered to be responsible for the biological activity of this herb. Five pentacyclic and two tetracyclic alkaloids were studied by solid-state NMR and theoretical GIAO DFT methods. The (13)C and (15)N CPMAS NMR spectra were recorded for mitraphylline, isomitraphylline, pteropodine (uncarine C), isopteropodine (uncarine E), speciophylline (uncarine D), rhynchophylline and isorhynchophylline. Theoretical GIAO DFT calculations of shielding constants provide arguments for identification of asymmetric centers and proper assignment of NMR spectra. These alkaloids are 7R/7S and 20R/20S stereoisomeric pairs. Based on the (13)C CP MAS chemical shifts the 7S alkaloids (delta C3 70-71ppm) can be easily and conveniently distinguished from 7R (deltaC3 74.5-74.9ppm), also 20R (deltaC20 41.3-41.7ppm) from the 20S (deltaC20 36.3-38.3ppm). The epiallo-type isomer (3R, 20S) of speciophylline is characterized by a larger (15)N MAS chemical shift of N4 (64.6ppm) than the allo-type (3S, 20S) of isopteropodine (deltaN4 53.3ppm). (15)N MAS chemical shifts of N1-H in pentacyclic alkaloids are within 131.9-140.4ppm.

  15. Light-mediated 15N fractionation in Caribbean gorgonian octocorals: implications for pollution monitoring

    Science.gov (United States)

    Baker, D. M.; Kim, K.; Andras, J. P.; Sparks, J. P.

    2011-09-01

    The stable nitrogen isotope ratio ( δ 15N) of coral tissue is a useful recorder of anthropogenic pollution in tropical marine ecosystems. However, little is known of the natural environmentally induced fractionations that affect our interpretation of coral δ 15N values. In symbiotic scleractinians, light affects metabolic fractionation of N during photosynthesis, which may confound the identification of N pollution between sites of varied depth or turbidity. Given the superiority of octocorals for δ 15N studies, our goal was to quantify the effect of light on gorgonian δ 15N in the context of monitoring N pollution sources. Using field collections, we show that δ 15N declined by 1.4‰ over 20 m depth in two species of gorgonians, the common sea fan, Gorgonia ventalina, and the slimy sea plume, Pseudopterogorgia americana. An 8-week laboratory experiment with P. americana showed that light, not temperature causes this variation, whereby the lowest fractionation of the N source was observed in the highest light treatment. Finally, we used a yearlong reciprocal depth transplant experiment to quantify the time frame over which δ 15N changes in G. ventalina as a function of light regime . Over the year, δ 15N was unchanged and increased slightly in the deep control colonies and shallow colonies transplanted to the deep site, respectively. Within 6 months, colonies transplanted from deep to shallow became enriched by 0.8‰, mirroring the enrichment observed in the shallow controls, which was likely due to the combined effect of an increase in the source δ 15N and reduced fractionation. We conclude that light affects gorgonian δ 15N fractionation and should be considered in sampling designs for N pollution monitoring. However, these fractionations are small relative to differences observed between natural and anthropogenic N sources.

  16. Measurement of marine productivity using 15N and 13C tracers: Some methodological aspects

    Indian Academy of Sciences (India)

    Naveen Gandhi; Sanjeev Kumar; S Prakash; R Ramesh; M S Sheshshayee

    2011-02-01

    Various experiments involving the measurement of new, regenerated and total productivity using 15N and 13C tracers were carried out in the Bay of Bengal (BOB) and in the Arabian Sea. Results from 15N tracer experiments indicate that nitrate uptake can be underestimated by experiments with incubation time > 4 hours. Indirect evidence suggests pico- and nano-phytoplankton, on their dominance over microphytoplankton, can also influence the f-ratios. Difference in energy requirement for assimilation of different nitrogen compounds decides the preferred nitrogen source during the early hours of incubation. Variation in light intensity during incubation also plays a significant role in the assimilation of nitrogen. Results from time course experiments with both 15N and 13C tracers suggest that photoinhibition appears significant in BOB and the Arabian Sea during noon. A significant correlation has been found in the productivity values obtained using 15N and 13C tracers.

  17. Gamma-ray width measurements in {sup 15}N at the ELBE nuclear resonance fluorescence setup

    Energy Technology Data Exchange (ETDEWEB)

    Szuecs, Tamas [Helmholtz-Zentrum Dresden-Rossendorf (HZDR), Dresden (Germany); MTA ATOMKI, Debrecen/Hungary (Hungary); Bemmerer, Daniel; Schwengner, Ronald [Helmholtz-Zentrum Dresden-Rossendorf (HZDR), Dresden (Germany); Massarczyk, Ralph; Takacs, Marcell; Wagner, Louis [Helmholtz-Zentrum Dresden-Rossendorf (HZDR), Dresden (Germany); TU Dresden (Germany)

    2014-07-01

    The stable nucleus {sup 15}N is the mirror of the astrophysically important {sup 15}O, compound nucleus of the leading reaction of the Bethe-Weizsaecker cycle of hydrogen burning. Most of the {sup 15}N level widths below the neutron and proton emission thresholds are known from just one nuclear resonance fluorescence (NRF) measurement published more than 30 years ago, with unsatisfactory precision on some cases. A recent experiment with the AGATA demonstrator array aimed to determine level widths with the Doppler Shift Attenuation Method (DSAM) in {sup 15}O and {sup 15}N populated in {sup 14}N + {sup 2}H reaction. In order to set a benchmark value for the upcoming AGATA demonstrator data, the widths of several {sup 15}N levels are being studied using the bremsstrahlung facility γELBE at the electron accelerator of Helmholtz-Zentrum Dresden-Rossendorf (HZDR). The γELBE experiment and its preliminary results are presented.

  18. Synthesis of {sup 15}N isotope labeled alanine; Sintese da alanina enriquecida com {sup 15}N

    Energy Technology Data Exchange (ETDEWEB)

    Oliveira, Claudineia R. de; Bendassolli, Jose Albertino; Sant' Ana, Carlos Roberto; Tagliassachi, Romulo Barbieri; Maximo, Everaldo; Prestes, Clelber Vieira [Centro de Energia Nuclear na Agricultura (CENA), Piracicaba, SP (Brazil). Dept. de Isotopos Estaveis]. E-mail: crolivei@cena.usp.br

    2005-07-01

    The application of light chemical elements and their stable isotopes in biological studies have been increased over the last years. The use of {sup 15}N labeled amino acids is an important tool for elucidation of peptides structures. This paper describe a method for the synthesis of {sup 15}N isotope labeled alanine at lower costs than international ones, as well as the details of the recovery system of the nitrogen residues. In the present work an amination of {alpha}-haloacids, with the bromopropionic carboxylic acid and labeled aqua ammonia ({sup 15}NH{sub 3} aq) was carried out. In order to avoid eventually losses of {sup 15}NH{sub 3}, special cares were adopted, since the production cost is high. Although the acquisition cost of the {sup 13}N (radioactive) labeled compounds is lower, the obtained stable tracer will allow the accomplishment of important studies of the nitrogen cycling in living things, less occupational and environment hazards, and the time limitation problems in field studies. The tests took place in triplicates with NH{sub 3} (aq) being employed. With the establishment of the system for {sup 15}NH{sub 3} recovery, an average of 94 % of the ammonia employed in the synthesis process was recovered. The purity of the amino acid was state determined by TLC (Thin Layer Chromatography) and HPLC (High-Performance Liquid Chromatography) with a fluorescence detector. The Rf and the retention time of the synthesized sample were similar the sigma standard. Finally, regarding the established conditions, it was possible to obtain the alanine with a production cost about 40 % lower than the international price. (author)

  19. Possibilities of climate reconstruction in the Holocene using {delta}{sup 13}C and {delta}{sup 2}H values from annual tree rings on the basis of climate chamber experiments and studies on present-day organisms; Moeglichkeiten der Klimarekonstruktion im Holozaen mit {delta}{sup 13}C- und {delta}{sup 2}H-Werten von Baum-Jahrringen auf der Basis von Klimakammerversuchen und Rezentstudien

    Energy Technology Data Exchange (ETDEWEB)

    Mayr, C.

    2002-07-01

    This study deals with the climatic information content of {sup 2}H and {sup 13}C levels in annual tree rings and plant material. The influence of variations in air temperature, relative humidity and water availability on stable isotope ratios in three different C{sub 3} plant species (Brassica oleracea, Eucalyptus globulus, Vicia faba) was studied in climate chamber experiments. Furthermore, calibration studies using {delta}{sup 13}C and {delta}{sup 2}H time series from Southern German spruce (Picea abies) from two stands (Schussbach, Klosterreichenbach) were performed. Correlations with meteorological data from a nearby meteorological station prove stable isotope ratios to be dependent on weather conditions in the summer months (June through August). Using the {delta}{sup 13}C ''response surfaces'' obtained from these experiments as well as correlations from long gridbox precipitation series it was shown that for the climate mode under study the {delta}{sup 13}C values largely reflect water availability to trees, which is greatly influenced by summer precipitation, especially at the more arid of the two sites. The results of the climate chamber experiments also suggest that the spruce {delta}{sup 2}H values largely reflect the isotope variation in soil water and hence the {delta}{sup 2}H fluctuations in summer precipitation. The study closes with a discussion of methodological approaches to creating long isotope series from annual tree rings of subfossil oak trees.

  20. Compound-specific 15N analysis of amino acids in 15N tracer experiments provide an estimate of newly synthesised soil protein from inorganic and organic substrates

    Science.gov (United States)

    Charteris, Alice; Michaelides, Katerina; Evershed, Richard

    2015-04-01

    Organic N concentrations far exceed those of inorganic N in most soils and despite much investigation, the composition and cycling of this complex pool of SOM remains poorly understood. A particular problem has been separating more recalcitrant soil organic N from that actively cycling through the soil system; an important consideration in N cycling studies and for the soil's nutrient supplying capacity. The use of 15N-labelled substrates as stable isotope tracers has contributed much to our understanding of the soil system, but the complexity and heterogeneity of soil organic N prevents thorough compound-specific 15N analyses of organic N compounds and makes it difficult to examine any 15N-labelled organic products in any detail. As a result, a significant proportion of previous work has either simply assumed that since the majority of soil N is organic, all of the 15N retained in the soil is organic N (e.g. Sebilo et al., 2013) or subtracted 15N-labelled inorganic compounds from bulk values (e.g. Pilbeam et al., 1997). While the latter approach is more accurate, these methods only provide an estimate of the bulk 15N value of an extremely complex and non-uniformly labelled organic pool. A more detailed approach has been to use microbial biomass extraction (Brookes et al., 1985) and subsequent N isotopic analysis to determine the 15N value of biomass-N, representing the fraction of 15N assimilated by microbes or the 15N cycling through the 'living' or 'active' portion of soil organic N. However, this extraction method can only generate estimates and some lack of confidence in its validity and reliability remains. Here, we present an alternative technique to obtain a measure of the assimilation of an applied 15N substrate by the soil microbial biomass and an estimate of the newly synthesized soil protein, which is representative of the magnitude of the active soil microbial biomass. The technique uses a stable isotope tracer and compound-specific 15N analysis, but

  1. Intra-annual variability of anatomical structure and delta(13)C values within tree rings of spruce and pine in alpine, temperate and boreal Europe.

    Science.gov (United States)

    Vaganov, Eugene A; Schulze, Ernst-Detlef; Skomarkova, Marina V; Knohl, Alexander; Brand, Willi A; Roscher, Christiane

    2009-10-01

    Tree-ring width, wood density, anatomical structure and (13)C/(12)C ratios expressed as delta(13)C-values of whole wood of Picea abies were investigated for trees growing in closed canopy forest stands. Samples were collected from the alpine Renon site in North Italy, the lowland Hainich site in Central Germany and the boreal Flakaliden site in North Sweden. In addition, Pinus cembra was studied at the alpine site and Pinus sylvestris at the boreal site. The density profiles of tree rings were measured using the DENDRO-2003 densitometer, delta(13)C was measured using high-resolution laser-ablation-combustion-gas chromatography-infra-red mass spectrometry and anatomical characteristics of tree rings (tracheid diameter, cell-wall thickness, cell-wall area and cell-lumen area) were measured using an image analyzer. Based on long-term statistics, climatic variables, such as temperature, precipitation, solar radiation and vapor pressure deficit, explained tree-ring width and wood density over consecutive years, while 29-58% of the variation in tree-ring width were explained by autocorrelation between tree rings. An intensive study of tree rings between 1999 and 2003 revealed that tree ring width and delta(13)C-values of whole wood were significantly correlated with length of the growing season, net radiation and vapor pressure deficit. The delta(13)C-values were not correlated with precipitation or temperature. A highly significant correlation was also found between delta(13)C of the early wood of one year and the late wood of the previous year, indicating a carry-over effect of the growing conditions of the previous season on current wood production. This latter effect may explain the high autocorrelation of long-term tree-ring statistics. The pattern, however, was complex, showing stepwise decreases as well as stepwise increases in the delta(13)C between late wood and early wood. The results are interpreted in the context of the biochemistry of wood formation and its

  2. The natural abundance of 15N in litter and soil profiles under six temperate tree species: N cycling depends on tree species traits and site fertility

    DEFF Research Database (Denmark)

    Callesen, Ingeborg; Nilsson, Lars Ola; Schmidt, Inger Kappel

    2013-01-01

    We investigated the influence of tree species on the natural 15N abundance in forest stands under elevated ambient N deposition.We analysed δ15N in litter, the forest floor and three mineral soil horizons along with ecosystem N status variables at six sites planted three decades ago with five...... European broadleaved tree species and Norway spruce.Litter δ15N and 15N enrichment factor (δ15Nlitter–δ15Nsoil) were positively correlated with N status based on soil and litter N pools, nitrification, subsoil nitrate concentration and forest growth. Tree species differences were also significant...... for these N variables and for the litter δ15N and enrichment factor. Litter from ash and sycamore maple with high N status and low fungal mycelia activity was enriched in 15N (+0.9 delta units) relative to other tree species (European beech, pedunculate oak, lime and Norway spruce) even though the latter...

  3. Phosphorus-31, sup 15 N, and sup 13 C NMR of glyphosate: Comparison of pH titrations to the herbicidal dead-end complex with 5-enolpyruvoylshikimate-3-phosphate synthase

    Energy Technology Data Exchange (ETDEWEB)

    Castellino, S.; Leo, G.C.; Sammons, R.D.; Sikorski, J.A. (Monsanto Agricultural Company, St. Louis, MO (USA))

    1989-05-02

    The herbicidal dead-end ternary complex (E{sup S3P}{sub Glyph}) of glyphosate (N-(phosphonomethyl)glycine) with 5-enolpyruvoylshikimate-3-phosphate synthase (EPSPS) and the substrate shikimate 3-phosphate (S3P) has been characterized by {sup 31}P, {sup 15}N, and {sup 13}C NMR. The NMR spectra of EPSPS-bound glyphosate show unique chemical shifts ({delta}) for each of the three nuclei. By {sup 31}P NMR, glyphosate in the dead-end complex is a distinct species 3.5 ppm downfield from free glyphosate. The {sup 13}C signal of glyphosate in the dead-end complex is shifted 4 ppm downfield from that of free glyphosate. The {sup 15}N signal for glyphosate (99%) in the dead-end complex is 5 ppm further downfield than that of any free zwitterionic species and 10 ppm downfield from that of the average free species at pH 10.1. The structures of each ionic state of glyphosate are modeled with force field calculations by using MacroModel. A correlation is made for the {sup 31}P {delta} and the C-P-O bond angle, and the {sup 13}C and {sup 15}N {delta} values are postulated to be related to C-C-O and C-N-C bond angles, respectively. The downfield {sup 31}P chemical shift perturbation for S3P in the EPSPS binary complex is consistent with ionization of the 3-phosphate of S3P upon binding. Comparison with the S3P {sup 31}P {delta} vs pH titration curve specifies predominantly the dianion of the 3-phosphate in the E{sup S3P} binary complex, while the E{sup S3P}{sub Glyph} complex indicates net protonation at the 3-phosphate. Chemical shift perturbations of this latter type may be explained by changes in the O-P-O bond angle.

  4. Spatial variation in the stable isotopes of 13C and 15N and trophic position of Leporinus friderici (Characiformes, Anostomidae in Corumbá Reservoir, Brazil

    Directory of Open Access Journals (Sweden)

    Alexandre L. Pereira

    2007-03-01

    Full Text Available Stable isotopes of carbon (delta13C and nitrogen (delta15N were used to describe sources of energy and trophic position for adult Leporinus friderici in the area of the Corumbá Reservoir, Brazil. Samples were collected from April 1999 to March 2000. Spatial variations were not identified in the isotopic composition. The maximum and minimum contribution of C4 plants calculated integrating the variation of plants and fish were 47.7% and 2.4%, respectively. Among C3 plants, periphyton presented closer isotopic values to those observed for fishes, corresponding to an important carbon source. The proportion of ingested plant item is larger in rivers upstream from the reservoir (42.7%, which justifies the smaller trophic level among there. However, in the reservoir, the ingestion of fish was 81.4%, while ingested plants contributed with 18.6%. Downstream from the dam, participation of plant item was even smaller (14.4%. Although the trophic position calculated with diet data was proportional to the one calculated with delta15N values, the former elevated the trophic level of L. friderici in the food web, because estimated trophic positions were based on fish items belonging to the 2nd (a and to the 3rd (b trophic levels.Isótopos estáveis de carbono (delta13C e nitrogênio (delta15N foram utilizados para descrever as fontes de energia e a posição trófica de adultos de Leporinus friderici na área do reservatório de Corumbá, Brasil. As amostras foram coletadas entre abril de 1999 e março de 2000. Variações espaciais não foram identificadas quanto à composição isotópica da espécie. As contribuições máximas e mínimas das plantas C4, foram de 47,7% e 2,4%, respectivamente. Entre as plantas C3, o perífiton correspondeu a uma das mais importantes fontes de carbono para a espécie, pois seus valores isotópicos foram os mais próximos àqueles observados para os peixes. A proporção ingerida do item vegetal foi maior em rios localizados

  5. The C$^{14}$N/C$^{15}$N Ratio in Diffuse Molecular Clouds

    CERN Document Server

    Ritchey, Adam M; Lambert, David L

    2015-01-01

    We report the first detection of C$^{15}$N in diffuse molecular gas from a detailed examination of CN absorption lines in archival VLT/UVES spectra of stars probing local diffuse clouds. Absorption from the C$^{15}$N isotopologue is confidently detected (at $\\gtrsim4\\sigma$) in three out of the four directions studied and appears as a very weak feature between the main $^{12}$CN and $^{13}$CN absorption components. Column densities for each CN isotopologue are determined through profile fitting, after accounting for weak additional line-of-sight components of $^{12}$CN, which are seen in the absorption profiles of CH and CH$^+$ as well. The weighted mean value of C$^{14}$N/C$^{15}$N for the three sight lines with detections of C$^{15}$N is $274\\pm18$. Since the diffuse molecular clouds toward our target stars have relatively high gas kinetic temperatures and relatively low visual extinctions, their C$^{14}$N/C$^{15}$N ratios should not be affected by chemical fractionation. The mean C$^{14}$N/C$^{15}$N ratio ...

  6. The natural abundance of 15N in plant and soil-available N indicates a shift of main plant N resources to NO3(-) from NH4(+) along the N leaching gradient.

    Science.gov (United States)

    Takebayashi, Yu; Koba, Keisuke; Sasaki, Yuji; Fang, Yunting; Yoh, Muneoki

    2010-04-15

    To investigate which of ammonium (NH(4)(+)) or nitrate (NO(3)(-)) is used by plants at gradient sites with different nitrogen (N) availability, we measured the natural abundance of (15)N in foliage and soil extractable N. Hinoki cypress (Chamaecyparis obtusa Endlicher) planted broadly in Japan was selected for use in this study. We estimated the source proportion of foliar N (NH(4)(+) vs. NO(3)(-)) quantitatively using mass balance equations. The results showed that C. obtusa used mainly NH(4)(+) in N-limited forests, although the dependence of C. obtusa on NO(3)(-) was greater in other NO(3)(-)-rich forests. We regarded dissolved organic N (DON) as a potential N source because a previous study demonstrated that C. obtusa can take up glycine. Thus we added DON to our mass balance equations and calculated the source proportion using an isotope-mixing model (IsoSource model). The results still showed a positive correlation between the calculated plant N proportion of NO(3)(-) and the NO(3)(-) pool size in the soil, indicating that high NO(3)(-) availability increases the reliance of C. obtusa on NO(3)(-). Our data suggest the shift of the N source for C. obtusa from NH(4)(+) to NO(3)(-) according to the relative availability of NO(3)(-). They also show the potential of the foliar delta(15)N of C. obtusa as an indicator of the N status in forest ecosystems with the help of the delta(15)N values of soil inorganic and organic N.

  7. Employee Training Needs and Perceived Value of Training in the Pearl River Delta of China: A Human Capital Development Approach

    Science.gov (United States)

    Au, Alan Kai Ming; Altman, Yochanan; Roussel, Josse

    2008-01-01

    Purpose: This paper aims to explore Hong Kong firms' training needs in the Pearl River Delta, a booming region in the fast growing People Republic of China economy, by resorting to a human capital approach. Also, to identify the training policies selected by those firms in order to cater for those needs. Design/methodology/approach: A survey based…

  8. Unusually negative nitrogen isotopic compositions (δ15N of mangroves and lichens in an oligotrophic, microbially-influenced ecosystem

    Directory of Open Access Journals (Sweden)

    I. Romero

    2008-12-01

    Full Text Available Extremes in δ15N values in mangrove tissues and lichens (range =+4 to −22‰ were measured from a mangrove forest ecosystem located on Twin Cays, offshore islands in Belize, Central America. The N isotopic compositions and concentrations of NH4+/NH3 in porewater, rainwater, and atmospheric ammonia, and the δ15N of lichens, mangrove leaves, roots, stems, and wood were examined to study the biogeochemical processes important for establishing these unusual N isotopic ratios. Dwarfed Rhizophora mangle trees had the most negative δ15N, whereas fringing Rhizophora trees, the most positive δ15N values. Porewater ammonium concentrations had little relationship to N isotopic fractionation in mangrove tissues. In dwarfed mangroves, the δ15N of fine and coarse roots were 6–9‰ more positive than leaf tissue from the same tree, indicating different sources of N for root and leaf tissues. When P was added to dwarfed mangrove trees without added N, δ15N increased within one year from −12‰ to −2‰, approaching the δ15N of porewater ammonium (δ15N=+4‰. Isotopically depleted ammonia in the atmosphere (δ15N=−19‰ and in rainwater (δ15N=−10‰ were found on Twin Cays. We propose that foliar uptake of these atmospheric sources by P-stressed, dwarfed mangrove trees and lichens can explain their very negative δ15N values. In environments where P is limiting for growth, uptake of atmospheric N by Rhizophora mangle may be an important adaptive strategy.

  9. How closely do the delta(13)C values of Crassulacean Acid metabolism plants reflect the proportion of CO(2) fixed during day and night?

    Science.gov (United States)

    Winter, Klaus; Holtum, Joseph A M

    2002-08-01

    The extent to which Crassulacean acid metabolism (CAM) plant delta(13)C values provide an index of the proportions of CO(2) fixed during daytime and nighttime was assessed. Shoots of seven CAM species (Aloe vera, Hylocereus monocanthus, Kalanchoe beharensis, Kalanchoe daigremontiana, Kalanchoe pinnata, Vanilla pauciflora, and Xerosicyos danguyi) and two C(3) species (teak [Tectona grandis] and Clusia sp.) were grown in a cuvette, and net CO(2) exchange was monitored for up to 51 d. In species exhibiting net dark CO(2) fixation, between 14% and 73.3% of the carbon gain occurred in the dark. delta(13)C values of tissues formed inside the cuvette ranged between -28.7 per thousand and -11.6 per thousand, and correlated linearly with the percentages of carbon gained in the light and in the dark. The delta(13)C values for new biomass obtained solely during the dark and light were estimated as -8.7 per thousand and -26.9 per thousand, respectively. For each 10% contribution of dark CO(2) fixation integrated over the entire experiment, the delta(13)C content of the tissue was, thus, approximately 1.8 per thousand less negative. Extrapolation of the observations to plants previously surveyed under natural conditions suggests that the most commonly expressed version of CAM in the field, "the typical CAM plant," involves plants that gain about 71% to 77% of their carbon by dark fixation, and that the isotopic signals of plants that obtain one-third or less of their carbon in the dark may be confused with C(3) plants when identified on the basis of carbon isotope content alone.

  10. Isolation and measurement of 15N2 from respiratory gases of animals administered 15N-labeled substances.

    Science.gov (United States)

    Springer, D L; Reed, D J; Dost, F N

    1981-01-01

    A method is described for collection of metabolic 15N2 from in vitro preparations or intact rats administered 15N-containing compounds. The methods enables routine collection and mass spectrometric measurement of as little as 10 mumol 15N2 respired by a rat over a 24-h period. A device is described that includes either an animal chamber or a tissue reaction vessel in a closed recycling atmosphere, with automatic O2 replenishment and removal of CO2 and water. It is capable of sustaining moderate vacuum and is coupled to a high-vacuum manifold designed to process the contained atmosphere and respiratory gases. The starting atmosphere is an 80:20 mix of sulfur hexafluoride and O2. Recovery of 15N2 gas from the system without an animal present was 101.3 +/- 5.75%. When 15N2 gas was very slowly infused iv into an animal, recovery was 89.1 +/- 5.38%. Use of the method in studies of the fate of [15N]hydrazine in rats indicated that about 15% of the administered hydrazine is rapidly converted to 15N2, followed by slower conversion of an additional 7-10% over the next several hours.

  11. Cartilage quality in rheumatoid arthritis: comparison of T2* mapping, native T1 mapping, dGEMRIC, {delta}R1 and value of pre-contrast imaging

    Energy Technology Data Exchange (ETDEWEB)

    Buchbender, Christian; Scherer, Axel; Kroepil, Patric; Quentin, Michael; Reichelt, Dorothea C.; Lanzman, Rotem S.; Mathys, Christian; Blondin, Dirk; Wittsack, Hans-Joerg; Antoch, Gerald; Miese, Falk [University Duesseldorf, Department of Diagnostic and Interventional Radiology, Medical Faculty, Duesseldorf (Germany); Koerbl, Birthe [Heinrich-Heine-University, Department of Endocrinology, Diabetology and Rheumatology, Medical Faculty, Duesseldorf (Germany); Heinrich-Heine-University, Leibniz Centre for Diabetes Research, Institute of Biometrics and Epidemiology, German Diabetes Centre, Duesseldorf (Germany); Bittersohl, Bernd; Zilkens, Christoph [Heinrich-Heine-University, Department of Orthopaedics, Medical Faculty, Duesseldorf (Germany); Hofer, Matthias [Heinrich-Heine-University, Medical Education Group, Medical School, Duesseldorf (Germany); Schneider, Matthias; Ostendorf, Benedikt [Heinrich-Heine-University, Department of Endocrinology, Diabetology and Rheumatology, Medical Faculty, Duesseldorf (Germany)

    2012-06-15

    To prospectively evaluate four non-invasive markers of cartilage quality - T2* mapping, native T1 mapping, dGEMRIC and {delta}R1 - in healthy volunteers and rheumatoid arthritis (RA) patients. Cartilage of metacarpophalangeal (MCP) joints II were imaged in 28 consecutive subjects: 12 healthy volunteers [9 women, mean (SD) age 52.67 (9.75) years, range 30-66] and 16 RA patients with MCP II involvement [12 women, mean (SD) age 58.06 (12.88) years, range 35-76]. Sagittal T2* mapping was performed with a multi-echo gradient-echo on a 3 T MRI scanner. For T1 mapping the dual flip angle method was applied prior to native T1 mapping and 40 min after gadolinium application (delayed gadolinium-enhanced MRI of cartilage, dGEMRIC, T1{sub Gd}). The difference in the longitudinal relaxation rate induced by gadolinium ({delta}R1) was calculated. The area under the receiver operating characteristic curve (AROC) was used to test for differentiation of RA patients from healthy volunteers. dGEMRIC (AUC 0.81) and {delta}R1 (AUC 0.75) significantly differentiated RA patients from controls. T2* mapping (AUC 0.66) and native T1 mapping (AUC 0.66) were not significantly different in RA patients compared to controls. The data support the use of dGEMRIC for the assessment of MCP joint cartilage quality in RA. T2* and native T1 mapping are of low diagnostic value. Pre-contrast T1 mapping for the calculation of {delta}R1 does not increase the diagnostic value of dGEMRIC. (orig.)

  12. 15N Hyperpolarization by Reversible Exchange Using SABRE-SHEATH

    OpenAIRE

    2015-01-01

    NMR signal amplification by reversible exchange (SABRE) is a NMR hyperpolarization technique that enables nuclear spin polarization enhancement of molecules via concurrent chemical exchange of a target substrate and parahydrogen (the source of spin order) on an iridium catalyst. Recently, we demonstrated that conducting SABRE in microtesla fields provided by a magnetic shield enables up to 10% 15N-polarization (Theis, T.; et al. J. Am. Chem. Soc. 2015, 137, 1404). Hyperpolarization on 15N (an...

  13. Determination of level widths in 15N using nuclear resonance fluorescence

    Directory of Open Access Journals (Sweden)

    Szücs T.

    2015-01-01

    Full Text Available Level widths in 15N have been measured with the nuclear resonance fluorescence (NRF technique. Solid nitrogen compounds, bremsstrahlung, and HPGe detectors have been used as target, beam, and detectors, respectively. The preliminarily level widths are in agreement with the literature values, but more precise.

  14. 15N Fractionation in Star-Forming Regions and Solar System Objects

    Science.gov (United States)

    Wirstrom, Eva; Milam, Stefanie; Adande, GIlles; Charnley, Steven; Cordiner, Martin

    2015-01-01

    A central issue for understanding the formation and evolution of matter in the early Solar System is the relationship between the chemical composition of star-forming interstellar clouds and that of primitive Solar System materials. The pristinemolecular content of comets, interplanetary dust particles and carbonaceous chondrites show significant bulk nitrogen isotopic fractionation relative to the solar value, 14N15N 440. In addition, high spatial resolution measurements in primitive materials locally show even more extreme enhancements of 14N15N 100.

  15. The 15N isotope to evaluate fertilizer nitrogen absorption efficiency by the coffee plant.

    Science.gov (United States)

    Fenilli, Tatiele A B; Reichart, Klaus; Bacchi, Osny O S; Trivelin, Paulo C O; Dourado-Neto, Durval

    2007-12-01

    The use of the 15N label for agronomic research involving nitrogen (N) cycling and the fate of fertilizer-N is well established, however, in the case of long term experimentation with perennial crops like citrus, coffee and rubber tree, there are still shortcomings mainly due to large plant size, sampling procedures, detection levels and interferences on the system. This report tries to contribute methodologically to the design and development of 15N labeled fertilizer experiments, using as an example a coffee crop fertilized with 15N labeled ammonium sulfate, which was followed for two years. The N of the plant derived from the fertilizer was studied in the different parts of the coffee plant in order to evaluate its distribution within the plant and the agronomic efficiency of the fertilizer application practice. An enrichment of the fertilizer-N of the order of 2% 15N abundance was sufficient to study N absorption rates and to establish fertilizer-N balances after one and two years of coffee cropping. The main source of errors in the estimated values lies in the inherent variability among field replicates and not in the measurements of N contents and 15N enrichments of plant material by mass-spectrometry.

  16. The {sup 15}N isotope to evaluate fertilizer nitrogen absorption efficiency by the coffee plant

    Energy Technology Data Exchange (ETDEWEB)

    Fenilli, Tatiele A.B. [Universidade Regional de Blumenau, (FURB), SC (Brazil); Reichart, Klaus; Bacchi, Osny O.S.; Trivelin, Paulo Cesar Ocheuze [Centro de Energia Nuclear na Agricultura (CENA/USP), Piracicaba, SP (Brazil)]. E-mail: klaus@cena.usp.br; Dourado-Neto, Durval [Universidade de Sao Paulo (USP), Piracicaba, SP (Brazil). Escola Superior de Agricultura Luiz de Queiroz (ESALQ)

    2007-12-15

    The use of the {sup 15}N label for agronomic research involving nitrogen (N) cycling and the fate of fertilizer-N is well established, however, in the case of long term experimentation with perennial crops like citrus, coffee and rubber tree, there are still shortcomings mainly due to large plant size, sampling procedures, detection levels and interferences on the system. This report tries to contribute methodologically to the design and development of {sup 15}N labeled fertilizer experiments, using as an example a coffee crop fertilized with {sup 15}N labeled ammonium sulfate, which was followed for two years. The N of the plant derived from the fertilizer was studied in the different parts of the coffee plant in order to evaluate its distribution within the plant and the agronomic efficiency of the fertilizer application practice. An enrichment of the fertilizer-N of the order of 2% {sup 15}N abundance was sufficient to study N absorption rates and to establish fertilizer-N balances after one and two years of coffee cropping. The main source of errors in the estimated values lies in the inherent variability among field replicates and not in the measurements of N contents and {sup 15}N enrichments of plant material by mass-spectrometry. (author)

  17. Using a macroalgal δ15N bioassay to detect cruise ship waste water effluent inputs.

    Science.gov (United States)

    Kaldy, James

    2011-08-01

    Green macroalgae bioassays were used to determine if the δ15N signature of cruise ship waste water effluent (CSWWE) could be detected in a small harbor. Opportunistic green macroalgae (Ulva spp.) were collected, cultured under nutrient depleted conditions and characterized with regard to N content and δ15N. Samples of algae were used in controlled incubations to evaluate the direction of isotope shift from exposure to CSWWE. Algae samples exposed to CSWWE exhibited an increase of 1-2.5‰ in δ15N values indicating that the CSWWE had an enriched isotope signature. In contrast, algae samples exposed to field conditions exhibited a significant decrease in the observed δ15N indicating that a light N source was used. Isotopically light, riverine nitrogen derived from N2-fixing trees in the watershed may be a N source utilized by algae. These experiments indicate that the δ15N CSWWE signature was not detectable under the CSWWE loading conditions of this experiment.

  18. d15N dynamics of ammonium and particulate nitrogen during the growth season of a eutrophic estuary

    DEFF Research Database (Denmark)

    De Brabandere, Loreto; Brion, N.; Elskens, M.;

    2007-01-01

    We monitored the stable nitrogen isotopic composition (d15N) of suspended matter and ammonium in the freshwater stretch of the Scheldt estuary (Belgium) over a full year to investigate for seasonal evolution and possible co-variation between isotopic signatures. The d15N value of ammonium remained...... rather constant during winter (average = +11.4 pro mille) but increased significantly with the spring and summer bloom, reaching values as high as +70 pro mille. This enrichment of the ammonium pool in 15N coincided with significant ammonium depletion during summer period, suggesting a close causal...

  19. Solvent effects on 15N NMR coordination shifts.

    Science.gov (United States)

    Kleinmaier, Roland; Arenz, Sven; Karim, Alavi; Carlsson, Anna-Carin C; Erdélyi, Máté

    2013-01-01

    (15)N NMR chemical shift became a broadly utilized tool for characterization of complex structures and comparison of their properties. Despite the lack of systematic studies, the influence of solvent on the nitrogen coordination shift, Δ(15)N(coord), was hitherto claimed to be negligible. Herein, we report the dramatic impact of the local environment and in particular that of the interplay between solvent and substituents on Δ(15)N(coord). The comparative study of CDCl(3) and CD(3)CN solutions of silver(I)-bis(pyridine) and silver(I)-bis(pyridylethynyl)benzene complexes revealed the strong solvent dependence of their (15)N NMR chemical shift, with a solvent dependent variation of up to 40 ppm for one and the same complex. The primary influence of the effect of substituent and counter ion on the (15)N NMR chemical shifts is rationalized by corroborating Density-Functional Theory (nor discrete Fourier transform) calculations on the B3LYP/6-311 + G(2d,p)//B3LYP/6-31G(d) level. Cooperative effects have to be taken into account for a comprehensive description of the coordination shift and thus the structure of silver complexes in solution. Our results demonstrate that interpretation of Δ(15)N(coord) in terms of coordination strength must always consider the solvent and counter ion. The comparable magnitude of Δ(15)N(coord) for reported transition metal complexes makes the principal findings most likely general for a broad scale of complexes of nitrogen donor ligands, which are in frequent use in modern organometallic chemistry.

  20. Atmospheric CO{sub 2} concentrations and {delta}{sup 13}C values across the Antarctic Circumpolar Current between New Zealand and Antarctica

    Energy Technology Data Exchange (ETDEWEB)

    Longinelli, Antonio; Selmo, Enricomaria [Univ. of Parma, (Italy). Dept. of Earth Sciences; Giglio, Federico; Langone, Leonardo; Lenaz, Renzo; Ori, Carlo [Consiglio Nazionale delle Ricerche, Bologna (Italy). Inst. of Marine Sciences, Marine Geology Section

    2007-02-15

    Measurements of atmospheric CO{sub 2} concentrations were repeatedly carried out on the vessel 'Italica' of the Italian National Research Program in Antarctica, during cruises from Italy to Antarctica. Discrete air samples were also collected in 4-L Pyrex flasks during these cruises in order to carry out {delta}{sup 13}C analyses on atmospheric CO{sub 2}. The results acquired between New Zealand and Antarctica are reported here. The mean growth rate of the CO{sub 2} concentration from 1996 to 2003 in this area of the Southern Oceans is of about 1.8 ppmv/yr, in good agreement with NOAA/CMDL measurements. The rates of increase from cruise to cruise are rather variable. From 1996-1997 to 1998-1999 cruise the yearly growth rate is 2.75 ppmv/yr, close to the large growth rates measured in several areas and mainly related to the most severe El Nino event of the last years. The other yearly growth rates are of about 1.3 and 2 ppmv for the periods 1998-1999 to 2001-2002 and 2001-2002 to 2003-2004, respectively. The large difference between these two values is probably related to the uncertainty on the only two 2001-2002 discrete measurements of CO{sub 2} concentration in this area. The measured {delta}{sup 13}C values show two completely different distributions and a large interannual variability. The 1998-1999, 2002-2003, and 2003-2004 results obtained between about 55 deg S and 65 deg S across the Antarctic Polar Front show a marked negativization of up to more than 0.2% when compared to the background values. The results are related to local source regions of CO{sub 2}, as frequently found in the Southern Ocean by several authors; the negative {delta}{sup 13}C values are tentatively related to the possible contribution of different causes. Among them, the southward negative gradient of {delta}{sup 13}C of the dissolved inorganic carbon, the contribution from upwelling deep waters and from subsurface processes between the Northern SubAntarctic Front and the

  1. Atmospheric CO{sub 2} concentrations and (delta){sup 13}C values across the Antarctic Circumpolar Current between New Zealand and Antarctica

    Energy Technology Data Exchange (ETDEWEB)

    Longinelli, Antonio; Selmo, Enricomaria [Univ. of Parma, (Italy). Dept. of Earth Sciences; Giglio, Federico; Langone, Leonardo; Lenaz, Renzo; Ori, Carlo [Consiglio Nazionale delle Ricerche, Bologna (Italy). Inst. of Marine Sciences, Marine Geology Section

    2007-02-15

    Measurements of atmospheric CO{sub 2} concentrations were repeatedly carried out on the vessel 'Italica' of the Italian National Research Program in Antarctica, during cruises from Italy to Antarctica. Discrete air samples were also collected in 4-L Pyrex flasks during these cruises in order to carry out (delta){sup 13}C analyses on atmospheric CO{sub 2}. The results acquired between New Zealand and Antarctica are reported here. The mean growth rate of the CO{sub 2} concentration from 1996 to 2003 in this area of the Southern Oceans is of about 1.8 ppmv/yr, in good agreement with NOAA/CMDL measurements. The rates of increase from cruise to cruise are rather variable. From 1996-1997 to 1998-1999 cruise the yearly growth rate is 2.75 ppmv/yr, close to the large growth rates measured in several areas and mainly related to the most severe El Nino event of the last years. The other yearly growth rates are of about 1.3 and 2 ppmv for the periods 1998-1999 to 2001-2002 and 2001-2002 to 2003-2004, respectively. The large difference between these two values is probably related to the uncertainty on the only two 2001-2002 discrete measurements of CO{sub 2} concentration in this area. The measured (delta){sup 13}C values show two completely different distributions and a large interannual variability. The 1998-1999, 2002-2003, and 2003-2004 results obtained between about 55 deg S and 65 deg S across the Antarctic Polar Front show a marked negativization of up to more than 0.2% when compared to the background values. The results are related to local source regions of CO{sub 2}, as frequently found in the Southern Ocean by several authors; the negative (delta){sup 13}C values are tentatively related to the possible contribution of different causes. Among them, the southward negative gradient of (delta){sup 13}C of the dissolved inorganic carbon, the contribution from upwelling deep waters and from subsurface processes between the Northern SubAntarctic Front and the

  2. Determination of the δ15N of total nitrogen in solids; RSIL lab code 2893

    Science.gov (United States)

    Revesz, Kinga; Qi, Haiping; Coplen, Tyler B.

    2006-01-01

    The purpose of the Reston Stable Isotope Laboratory (RSIL) lab code 2893 is to determine the δ(15N/14N), abbreviated as δ15N , of total nitrogen in solid samples. A Carlo Erba NC 2500 elemental analyzer (EA) is used to convert total nitrogen in a solid sample into N2 gas. The EA is connected to a continuous flow isotope-ratio mass spectrometer (CF-IRMS), which determines relative difference in the isotope-amount ratios of stable nitrogen isotopes (15N/14N)of the product N2 gas. The combustion is quantitative; no isotopic fractionation is involved. Samples are placed in a tin capsule and loaded into the Costech Zero Blank Autosampler of the EA. Under computer control, samples are dropped into a heated reaction tube that contains an oxidant, where the combustion takes place in a helium atmosphere containing an excess of oxygen gas. Combustion products are transported by a helium carrier through a reduction tube to remove excess oxygen and convert all nitrous oxides into N2 and through a drying tube to remove water. The gas-phase products, mainly CO2 and N2, are separated by a gas chromatograph. The gas is then introduced into the isotope-ratio mass spectrometer (IRMS) through a Finnigan MAT (now Thermo Scientific) ConFlo II interface, which also is used to inject N2 reference gas and helium for sample dilution. The IRMS is a Thermo Scientific Delta V Plus CF-IRMS. It has a universal triple collector, two wide cups with a narrow cup in the middle, capable of measuring mass/charge (m/z) 28, 29, 30, simultaneously. The ion beams from N2 are as follows: m/z 28 = N2 = 14N14N; m/z 29 = N2 = 14N15N primarily; m/z 30 = NO = 14N16O primarily, which is a sign of contamination or incomplete reduction.

  3. Seasonal inter-relationships in atmospheric methane and companion delta13C values: effects of sinks and sources

    Energy Technology Data Exchange (ETDEWEB)

    Lassey, K. R.; Mikaloff Fletcher, S. E. (NIWA, Wellington (New Zealand)), e-mail: k.lassey@niwa.co.nz; Allan, W. (Allan Planning and Research Ltd., Petone (New Zealand))

    2011-07-15

    Recent developments in applying carbon-isotope information to better understand regional and global methane budgets infer a strong role by a highly fractionating seasonal sink such as atomic chlorine. Specifically, OH as the predominant seasonal sink cannot account for the 'phase ellipses' based on observed seasonal cycles of methane mixing ratio and isotope ratio, delta13C. Although a strong role by atomic chlorine is inferred empirically, open questions remain about the interplay between sources and sinks in determining the properties of phase ellipses. This paper employs a simple didactic model of the seasonal cycling of atmospheric methane to understand such interplay. We demonstrate that a single seasonal sink and seasonal source act together to imprint anti-phase seasonalities on atmospheric methane and delta13C, which lead to phase ellipses that collapse onto a straight line with slope characteristic of that sink. This explains empirical findings of these anti-phase relationships in three-dimensional modelling studies. We also demonstrate that multiple seasonal sinks acting with a seasonal source can yield surprising properties for the phase ellipse that not only explain some features of phase ellipses reported in modelling studies but also have the potential to explain marked inter-annual variation in phase ellipses based on observation

  4. Soil microarthropods and their bioindicator value regarding the bio-edaphic conditions in forest ecosystems of Danube Delta

    Directory of Open Access Journals (Sweden)

    Călugăr A.,

    2016-05-01

    Full Text Available The main objective of this study was to compare soil mesofauna communities in natural and anthropogenic forests from Danube Delta Biosphere Reserve and establish a baseline data in monitoring the disturbed sites. The abundance and diversity of edaphic microarthropods were analyzed in five plots, three of them being natural forests and two plantations (Canada poplar, and respectively willow. The mites from Trombidiformes and Oribatida were closely investigated being identified at family level. Qualitative analysis of edaphic microarthropods evidences numerical dominance of mites, excepting only one stand (Canada poplar plantation. Among mites Oribatida owns the biggest weight (76.6 - 94.1% of the total mites, followed by Trombidiformes or Mesostigmata. Among insects the collembolans hold higher density in the poplar plantation, and the lowest one in the willow plantation. Structure of mites communities differs between the investigated ecosystems both in quantitative and qualitative aspects depending on particular conditions of each plot.

  5. Concentrations and {delta}{sup 13}C values of atmospheric CO{sub 2} from oceanic atmosphere through time: polluted and non-polluted areas

    Energy Technology Data Exchange (ETDEWEB)

    Longinelli, Antonio; Selmo, Enrico [Univ. of Parma (Italy). Dept. of Earth Sciences; Lenaz, Renzo; Ori, Carlo [C.N.R., ISMAR, Bologna (Italy). Dept. of Marine Geology

    2005-11-01

    CO{sub 2} is one of the primary agents of global climate changes. The increase of atmospheric CO{sub 2} concentration is essentially related to human-induced emissions and, particularly, to the burning of fossil fuel whose {delta}{sup 13}C values are quite negative. Consequently, an increase of the CO{sub 2} concentration in the atmosphere should be paralleled by a decrease of its {delta}{sup 13}C. Continuous and/or spot measurements of CO{sub 2} concentrations were repeatedly carried out during the last decade and in the same period of the year along hemispheric courses from Italy to Antarctica on a vessel of the Italian National Research Program in Antarctica. During these expeditions, discrete air samples were also collected in 4-l Pyrex flasks in order to carry out precise carbon isotope analyses on atmospheric CO{sub 2} from different areas, including theoretically 'clean' open ocean areas, with the main purpose of comparing these open ocean results with the results obtained by the National Oceanic and Atmospheric Administration/World Meteorological Organization (NOAA/WMO) at land-based stations. According to the data obtained for these two variables, a relatively large atmospheric pollution is apparent in the Mediterranean area where the CO{sub 2} concentration has reached the value of 384 ppmv while quite negative {delta}{sup 13}C values have been measured only occasionally. In this area, southerly winds probably help to reduce the effect of atmospheric pollution even though, despite a large variability of CO{sub 2} concentrations, these values are consistently higher than those measured in open ocean areas by a few ppmv to about 10 ppmv. A marked, though non-continuous, pollution is apparent in the area of the Bab-el-Mandeb strait where {delta}{sup 13}C values considerably more negative than in the Central and Southern Red Sea were measured. The concentration of atmospheric CO{sub 2} over the Central Indian Ocean increased from about 361 ppmv at

  6. Concentrations and (delta){sup 13}C values of atmospheric CO{sub 2} from oceanic atmosphere through time: polluted and non-polluted areas

    Energy Technology Data Exchange (ETDEWEB)

    Longinelli, Antonio; Selmo, Enrico [Univ. of Parma (Italy). Dept. of Earth Sciences; Lenaz, Renzo; Ori, Carlo [C.N.R., ISMAR, Bologna (Italy). Dept. of Marine Geology

    2005-11-15

    CO{sub 2} is one of the primary agents of global climate changes. The increase of atmospheric CO{sub 2} concentration is essentially related to human-induced emissions and, particularly, to the burning of fossil fuel whose (delta){sup 13}C values are quite negative. Consequently, an increase of the CO{sub 2} concentration in the atmosphere should be paralleled by a decrease of its (delta){sup 13}C. Continuous and/or spot measurements of CO{sub 2} concentrations were repeatedly carried out during the last decade and in the same period of the year along hemispheric courses from Italy to Antarctica on a vessel of the Italian National Research Program in Antarctica. During these expeditions, discrete air samples were also collected in 4-l Pyrex flasks in order to carry out precise carbon isotope analyses on atmospheric CO{sub 2} from different areas, including theoretically 'clean' open ocean areas, with the main purpose of comparing these open ocean results with the results obtained by the National Oceanic and Atmospheric Administration/World Meteorological Organization (NOAA/WMO) at land-based stations. According to the data obtained for these two variables, a relatively large atmospheric pollution is apparent in the Mediterranean area where the CO{sub 2} concentration has reached the value of 384 ppmv while quite negative (delta){sup 13}C values have been measured only occasionally. In this area, southerly winds probably help to reduce the effect of atmospheric pollution even though, despite a large variability of CO{sub 2} concentrations, these values are consistently higher than those measured in open ocean areas by a few ppmv to about 10 ppmv. A marked, though non-continuous, pollution is apparent in the area of the Bab-el-Mandeb strait where (delta){sup 13}C values considerably more negative than in the Central and Southern Red Sea were measured. The concentration of atmospheric CO{sub 2} over the Central Indian Ocean increased from about 361 ppmv at

  7. Constraints on oceanic N balance/imbalance from sedimentary 15N records

    Directory of Open Access Journals (Sweden)

    M. A. Altabet

    2007-01-01

    Full Text Available According to current best estimates, the modern ocean's N cycle is in severe deficit. N isotope budgeting provides an independent geochemical constraint in this regard as well as the only means for past reconstruction. Overall, it is the relative proportion of N2 fixation consumed by water column denitrification that sets average oceanic δ15N under steady-state conditions. Several factors (conversion of organic N to N2, Rayleigh closed and open system effects likely reduce the effective fractionation factor (ε for water column denitrification to about half the inherent microbial value for εden. If so, the average oceanic δ15N of ~5‰ is consistent with a canonical contribution from water column denitrification of 50% of the source flux from N2 fixation. If an imbalance in oceanic N sources and sinks changes this proportion then a transient in average oceanic δ15N would occur. Using a simple model, changing water column denitrification by ±30% or N2 fixation by ±15% produces detectable (>1‰ changes in average oceanic δ15N over one residence time period or more with corresponding changes in oceanic N inventory. Changing sedimentary denitrification produces no change in δ15N but does change N inventory. Sediment δ15N records from sites thought to be sensitive to oceanic average δ15N all show no detectible change over the last 3 kyr or so implying a balanced marine N budget over the latest Holocene. A mismatch in time scales is the most likely meaningful interpretation of the apparent conflict with modern flux estimates. Decadal to centennial scale oscillations between net N deficit and net surplus may occur but on the N residence timescale of several thousand years, net balance is achieved in sum. However, sediment δ15N records from the literature covering the period since the last glacial maximum show excursions of up to several ‰ that are consistent with sustained N deficit during the deglaciation followed by readjustment

  8. Kinetic 15N-isotope effects on algal growth

    Science.gov (United States)

    Andriukonis, Eivydas; Gorokhova, Elena

    2017-03-01

    Stable isotope labeling is a standard technique for tracing material transfer in molecular, ecological and biogeochemical studies. The main assumption in this approach is that the enrichment with a heavy isotope has no effect on the organism metabolism and growth, which is not consistent with current theoretical and empirical knowledge on kinetic isotope effects. Here, we demonstrate profound changes in growth dynamics of the green alga Raphidocelis subcapitata grown in 15N-enriched media. With increasing 15N concentration (0.37 to 50 at%), the lag phase increased, whereas maximal growth rate and total yield decreased; moreover, there was a negative relationship between the growth and the lag phase across the treatments. The latter suggests that a trade-off between growth rate and the ability to adapt to the high 15N environment may exist. Remarkably, the lag-phase response at 3.5 at% 15N was the shortest and deviated from the overall trend, thus providing partial support to the recently proposed Isotopic Resonance hypothesis, which predicts that certain isotopic composition is particularly favorable for living organisms. These findings confirm the occurrence of KIE in isotopically enriched algae and underline the importance of considering these effects when using stable isotope labeling in field and experimental studies.

  9. Stepwise enrichment of 15N along food chains: Further evidence and the relation between δ 15N and animal age

    Science.gov (United States)

    Minagawa, Masao; Wada, Eitaro

    1984-05-01

    The isotopic composition of nitrogen was measured in marine and fresh-water animals from the East China Sea, The Bering Sea, Lake Ashinoko and Usujiri intertidal zone. Primary producers, showed average δ15Nversus atmospheric nitrogen of +5.0%. (+3.4 to +7.5) in the Bering Sea and Lake Ashinoko, and +6.8%. (+6.0 to +7.6) in Usujiri intertidal zone. Blue green algae from the East China Sea show an average -0.55%. (-0.8 to +1.2). All consumers, Zooplankton, fish and bird exhibited Stepwise enrichment of 15N with increasing trophic level. The 15N enrichment at a single feeding process ranged from +1.3 to +5.3 averaging +3.4 ± 1.1%.. This isotopic fractionation seems to be independent of habitat. The effect of age in animals was obtained by analyzing two marine mussels. The soft tissue nitrogen showed +2.0%. enrichment relative to that of primary producers, and the magnitude was almost constant with shell ages ranging from 0 to 8 years. A similar 15N enrichment occurs in all Molluscs, Crustaceans, Insecta, Amphibia, Fish, Ave and Mammal species regardless of the difference in the form of excreted nitrogen and in laboratory cultured fish, brine shrimp and mice (+2.9 to +4.9%.). The excreted ammonia from guppy was sufficiently light to balance the concentration of 15N to animal body.

  10. Fertilizer nitrogen recovery of rice: /sup 15/N field studies (a short review)

    Energy Technology Data Exchange (ETDEWEB)

    Singh, B.; Katyal, J.C. (Punjab Agricultural Univ., Ludhiana (India). Dept. of Soils)

    1980-12-01

    Reliable quantitative estimates of fertilizer nitrogen recovery by rice are obtained in field investigations with /sup 15/N-labelled materials. Values obtained by conventional 'difference method' of comparing fertilized and unfertilized plots are typically larger than the actual values. Estimating the recovery of fertilizer nitrogen is not a goal in itself. Although it has been an essential component of limited number of /sup 15/N-field experiments conducted with rice so far; these provide little or no information about crop growth stages when fertilizer N is most efficiently utilized by rice plant. Recently, the path coefficient analysis has been used to analyse the effect of N uptake on the development of yield components and their contribution to grain yield. Nitrogen-15 fertilizers along with path coefficient analysis can prove particularly useful in comparing the efficiency of different N fertilizers and in the development of new and more efficient nitrogen sources and management practices.

  11. Foliar δ15N is affected by foliar nitrogen uptake, soil nitrogen, and mycorrhizae along a nitrogen deposition gradient.

    Science.gov (United States)

    Vallano, Dena M; Sparks, Jed P

    2013-05-01

    Foliar nitrogen isotope (δ(15)N) composition patterns have been linked to soil N, mycorrhizal fractionation, and within-plant fractionations. However, few studies have examined the potential importance of the direct foliar uptake of gaseous reactive N on foliar δ(15)N. Using an experimental set-up in which the rate of mycorrhizal infection was reduced using a fungicide, we examined the influence of mycorrhizae on foliar δ(15)N in potted red maple (Acer rubrum) seedlings along a regional N deposition gradient in New York State. Mycorrhizal associations altered foliar δ(15)N values in red maple seedlings from 0.06 to 0.74 ‰ across sites. At the same sites, we explored the predictive roles of direct foliar N uptake, soil δ(15)N, and mycorrhizae on foliar δ(15)N in adult stands of A. rubrum, American beech (Fagus grandifolia), black birch (Betula lenta), and red oak (Quercus rubra). Multiple regression analysis indicated that ambient atmospheric nitrogen dioxide (NO2) concentration explained 0, 69, 23, and 45 % of the variation in foliar δ(15)N in American beech, red maple, red oak, and black birch, respectively, after accounting for the influence of soil δ(15)N. There was no correlation between foliar δ(13)C and foliar %N with increasing atmospheric NO2 concentration in most species. Our findings suggest that total canopy uptake, and likely direct foliar N uptake, of pollution-derived atmospheric N deposition may significantly impact foliar δ(15)N in several dominant species occurring in temperate forest ecosystems.

  12. Diffusion technique for 15N and inorganic N analysis of low-N aqueous solutions and Kjeldahl digests.

    Science.gov (United States)

    Chen, Rui Rui; Dittert, Klaus

    2008-06-01

    Diffusion of ammonia is a common sample preparation method for the stable isotope analysis of inorganic nitrogen in aqueous solution. Classical diffusion methods usually require 6-12 days of diffusion and often focus on (15)N/(14)N analysis only. More recent studies have discussed whether complete N recovery was necessary for the precise analysis of stable N isotope ratios. In this paper we present a newly revised diffusion technique that allows correct and simultaneous determination of total N and (15)N at% from aqueous solutions and Kjeldahl digests, with N concentrations down to sub-0.5-mg N L(-1) levels, and it is tested under different conditions of (15)N isotope labelling. With the modification described, the diffusion time was reduced to 72 h, while the ratios of measured and expected (15)N at% were greater than 99% and the simultaneous recovery of total N was >95%. Analysis of soil microbial biomass N and its (15)N/(14)N ratio is one of the most important applications of this diffusion technique. An experiment with soil extracts spiked with (15)N-labelled yeast showed that predigestion was necessary to prevent serious N loss during Kjeldahl digestion of aqueous samples (i.e. soil extracts). The whole method of soil microbial biomass N preparation for (15)N/(14)N analysis included chloroform fumigation, predigestion, Kjeldahl digestion and diffusion. An experiment with soil spiked with (15)N-labelled yeast was carried out to evaluate the method. Results showed a highly significant correlation of recovered and added N, with the same recovery rate (0.21) of both total N and (15)N. A k(N) value of 0.25 was obtained based on the data. In conclusion, the diffusion method works for soil extracts and microbial biomass N determination and hence could be useful in many types of soil/water studies.

  13. Geomorphic control on the δ15N of mountain forests

    Directory of Open Access Journals (Sweden)

    R. G. Hilton

    2013-03-01

    Full Text Available Mountain forests are subject to high rates of physical erosion which can export particulate nitrogen from ecosystems. However, the impact of geomorphic processes on nitrogen budgets remains poorly constrained. We have used the elemental and isotopic composition of soil and plant organic matter to investigate nitrogen cycling in the mountain forest of Taiwan, from 24 sites with distinct geomorphic (topographic slope and climatic (precipitation, temperature characteristics. The organic carbon to nitrogen ratio of soil organic matter decreased with soil 14C age, providing constraint on average rates of nitrogen loss using a mass balance model. Model predictions suggest that present day estimates of nitrogen deposition exceed contemporary and historic nitrogen losses. We found ∼6‰ variability in the stable isotopic composition (δ15N of soil and plants which was not related to soil 14C age or climatic conditions. Instead, δ15N was significantly, negatively correlated with topographic slope. Using the mass balance model, we demonstrate that the correlation can be explained by an increase in nitrogen loss by non-fractioning pathways on steeper slopes, where physical erosion most effectively removes particulate nitrogen. Published data from forests on steep slopes are consistent with the correlation. Based on our dataset and these observations, we hypothesise that variable physical erosion rates can significantly influence soil δ15N, and suggest particulate nitrogen export is a major, yet underappreciated, loss term in the nitrogen budget of mountain forests.

  14. Nitrogen use efficiency evaluation of aerobic rice under field capacity water potential using {sup 15}N isotopic tracer technique

    Energy Technology Data Exchange (ETDEWEB)

    Wahid, Ahmad Nazrul Abd, E-mail: a-nazrul@nuclearmalaysia.gov.my [Faculty of Science and Technology, Universiti Kebangsaan Malaysia, Bangi, 43600, Selangor (Malaysia); Malaysian Nuclear Agency, Bangi, 43000 Kajang, Selangor (Malaysia); Rahim, Sahibin Abd, E-mail: haiyan@ukm.edu.my [Faculty of Science and Technology, Universiti Kebangsaan Malaysia, Bangi, 43600, Selangor (Malaysia); Rahim, Khairuddin Abdul; Harun, Abdul Rahim [Malaysian Nuclear Agency, Bangi, 43000 Kajang, Selangor (Malaysia)

    2015-09-25

    This study was carried out to evaluate the efficiency use of the nitrogen fertilizer on aerobic rice varieties MR219-4 and MR219-9 which were grown aerobically under field capacity water potential at the controlled environment area or shield house. Direct {sup 15}N isotope tracer method was used in this study, whereby the {sup 15}N isotope was utilized as a tracer for nitrogen nutrient uptake. {sup 15}N isotope presence in the samples is determined by using emission spectrometer analysis and percentage of total nitrogen is determined by using Kjeldahl method. {sup 15}N atom access value contained in the sample will be used in determining the effectiveness of the use of nitrogen in fertilizers through the specific calculation formulas. In this work, the data several data of nitrogen derived from fertilizer (Ndff), total nitrogen, nitrogen uptake and nitrogen use efficiency was obtained.

  15. Nitrogen use efficiency evaluation of aerobic rice under field capacity water potential using 15N isotopic tracer technique

    Science.gov (United States)

    Wahid, Ahmad Nazrul Abd; Rahim, Sahibin Abd; Rahim, Khairuddin Abdul; Harun, Abdul Rahim

    2015-09-01

    This study was carried out to evaluate the efficiency use of the nitrogen fertilizer on aerobic rice varieties MR219-4 and MR219-9 which were grown aerobically under field capacity water potential at the controlled environment area or shield house. Direct 15N isotope tracer method was used in this study, whereby the 15N isotope was utilized as a tracer for nitrogen nutrient uptake. 15N isotope presence in the samples is determined by using emission spectrometer analysis and percentage of total nitrogen is determined by using Kjeldahl method. 15N atom access value contained in the sample will be used in determining the effectiveness of the use of nitrogen in fertilizers through the specific calculation formulas. In this work, the data several data of nitrogen derived from fertilizer (Ndff), total nitrogen, nitrogen uptake and nitrogen use efficiency was obtained.

  16. Design and development of a simple laboratory model to detect (15)N enrichment in cyanobacterial biomass and extra cellular ammonia using (15)N gas.

    Science.gov (United States)

    Selvakumar, G; Gopalaswamy, G; Arulmozhiselvan, K

    2007-03-01

    A laboratory scale working model that could detect the (15)N enrichment in cyanobacterial biomass and extracellular ammonia, using (15)N gas under in vitro conditions was designed and fabricated. Using the model, (15)N enrichment of 0.48% atom excess was detected in the cyanobacterial biomass on the 30 d after inoculation. The (15)N enrichment increased linearly in the extracellular ammoniacal fraction from the 20 d onward. The model would prove to be a useful tool to quantify the extent of (15)N enrichment under in vitro conditions using (15)N gas.

  17. Novel labeling technique illustrates transfer of 15N2 from Sphagnum moss to vascular plants via diazotrophic nitrogen fixation

    Science.gov (United States)

    Thorp, N. R.; Vile, M. A.; Wieder, R.

    2013-12-01

    transferred to P. mariana roots (mean δ15N at 1 and 2 months of 15.26 × 3.30 and 16.19 × 1.21) more than shoots (mean δ15N at 1 and 2 months of 6.57 × 0.52 and 4.67×0.17) (initial δ15N values of roots and shoots of 2.16 × 0.37 and 5.54 × 0.35, respectively). Nitrogen also was transferred to V. oxycoccos roots (δ15N at 2 months of 21.46 × 3.61) more than shoots (δ15N 2 months of -2.17 × 0.23) (initial δ15N values of roots and shoots of -6.41 × 0.21 and -6.85 × 0.15, respectively). A two-way ANOVA and Tukey's HSD verified that both vascular plants' roots were significantly enriched with 15N (P. mariana roots; p < 0.0001, V. oxycoccus roots; p < 0.0001) after 1 month. These results indicate that bog vascular plants may derive considerable nitrogen from biological N2-fixation taking place in Sphagnum moss capitula. The experiment was subsequently repeated in-situ.

  18. Determination of the δ15N and δ13C of total nitrogen and carbon in solids; RSIL lab code 1832

    Science.gov (United States)

    Revesz, Kinga; Qi, Haiping; Coplan, Tyler B.

    2006-01-01

    The purpose of the Reston Stable Isotope Laboratory (RSIL) lab code 1832 is to determine the δ(15N/14N), abbreviated as δ15N, and the δ(13C/12C), abbreviated as δ13C, of total nitrogen and carbon in a solid sample. A Carlo Erba NC 2500 elemental analyzer (EA) is used to convert total nitrogen and carbon in a solid sample into N2 and CO2 gas. The EA is connected to a continuous flow isotope-ratio mass spectrometer (CF-IRMS), which determines the relative difference in stable nitrogen isotope-amount ratio (15N/14N) of the product N2 gas and the relative difference in stable carbon isotope-amount ratio (13C/12C) of the product CO2 gas. The combustion is quantitative; no isotopic fractionation is involved. Samples are placed in tin capsules and loaded into a Costech Zero Blank Autosampler on the EA. Under computer control, samples then are dropped into a heated reaction tube that contains an oxidant, where combustion takes place in a helium atmosphere containing an excess of oxygen gas. Combustion products are transported by a helium carrier through a reduction furnace to remove excess oxygen and to convert all nitrous oxides into N2 and through a drying tube to remove water. The gas-phase products, mainly CO2 and N2, are separated by a gas chromatograph. The gas is then introduced into the IRMS through a Finnigan MAT (now Thermo Scientific) ConFlo II interface. The Finnigan MAT ConFlo II interface is used for introducing not only sample into the IRMS but also N2 and CO2 reference gases and helium for sample dilution. The flash combustion is quantitative; no isotopic fractionation is involved. The IRMS is a Thermo Scientific Delta V CF-IRMS. It has a universal triple collector, two wide cups with a narrow cup in the middle; it is capable of measuring mass/charge (m/z) 28, 29, 30 or with a magnet current change 44, 45, 46, simultaneously. The ion beams from these m/z values are as follows: m/z 28 = N2 = 14N/14N; m/z 29 = N2 = 14N/15N primarily; m/z 30 = NO = 14N/16O

  19. 15N NMR chemical shifts in papaverine decomposition products

    Science.gov (United States)

    Czyrski, Andrzej; Girreser, Ulrich; Hermann, Tadeusz

    2013-03-01

    Papaverine can be easily oxidized to papaverinol, papaveraldine and 2,3,9,10-tetramethoxy-12-oxo-12H-indolo[2,1-a]isoquinolinium chloride. On addition of alkali solution the latter compound forms 2-(2-carboxy-4,5-dimethoxyphenyl)-6,7-dimethoxyisoquinolinium inner salt. Together with these structures the interesting 13-(3,4-dimethoxyphenyl)-2,3,8,9-tetramethoxy-6a-12a-diazadibenzo[a,g]fluorenylium chloride is discussed, which is formed in the Gadamer-Schulemann reaction of papaverine as a side product. This letter reports the 15N NMR spectra of the above mentioned compounds.

  20. Variability in δ{sup 15}N of intertidal brown algae along a salinity gradient: Differential impact of nitrogen sources

    Energy Technology Data Exchange (ETDEWEB)

    Viana, Inés G., E-mail: inesgviana@gmail.com; Bode, Antonio

    2015-04-15

    While it is generally agreed that δ{sup 15}N of brown macroalgae can discriminate between anthropogenic and natural sources of nitrogen, this study provides new insights on net fractionation processes occurring in some of these species. The contribution of continental and marine sources of nitrogen to benthic macroalgae in the estuary-ria system of A Coruña (NW Spain) was investigated by analyzing the temporal (at a monthly and annual basis) and spatial (up to 10 km) variability of δ{sup 15}N in the macroalgae Ascophyllum nodosum and three species of the genus Fucus (F. serratus, F. spiralis and F. vesiculosus). Total nitrate and ammonium concentrations and δ{sup 15}N-DIN, along with salinity and temperature in seawater were also studied to address the sources of such variability. Macroalgal δ{sup 15}N and nutrient concentrations decreased from estuarine to marine waters, suggesting larger dominance of anthropogenic nitrogen sources in the estuary. However, δ{sup 15}N values of macroalgae were generally higher than those of ambient nitrogen at all temporal and spatial scales considered. This suggests that the isotopic composition of these macroalgae is strongly affected by fractionation during uptake, assimilation or release of nitrogen. The absence of correlation between macroalgal and water samples suggests that the δ{sup 15}N of the species considered cannot be used for monitoring short-term changes. But their long lifespan and slow turnover rates make them suitable to determine the impact of the different nitrogen sources integrated over long-time periods. - Highlights: • Variability of Fucacean δ{sup 15}N indicates N sources along a salinity gradient. • δ{sup 15}N of Fucaceae and seawater are not correlated at short time scales. • Isotopic fractionation in macroalgal tissue varies at seasonal and at local scale. • Fucacean species are suitable for monitoring chronic N loadings.

  1. Leaf δ15N as a temporal integrator of nitrogen-cycling processes at the Mojave Desert FACE experiment

    Science.gov (United States)

    Sonderegger, D.; Koyama, A.; Jin, V.; Billings, S. A.; Ogle, K.; Evans, R. D.

    2011-12-01

    Ecosystem response to elevated carbon dioxide (CO2) in arid environments is regulated primarily by water, which may interact with nitrogen availability. Leaf nitrogen isotope composition (δ15N) can serve as an important indicator of changes in nitrogen dynamics by integrating changes in plant physiology and ecosystem biogeochemical processes. Because of this temporal integration, careful modeling of the antecedent conditions is necessary for understanding the processes driving variation in leaf δ15N. We measured leaf δ15N of Larrea tridentata (creosotebush) over the 10-year lifetime of the Nevada Desert Free-Air CO2 Enrichment (FACE) experiment. Leaf δ15N exhibited two patterns. First, elevated atmospheric CO2 significantly increased Larrea leaf δ15N by approximately 2 to 3 % compared to plants exposed to ambient CO2 concentrations Second, plants in both CO2 treatments exhibited significant seasonal cycles in leaf δ15N, with higher values during the fall and winter seasons. We modeled leaf δ15N using a hierarchical Bayesian framework that incorporated soil moisture, temperature, and the Palmer Drought Severity Index (PDSI) covariates in addition to a CO2 treatment effect and plot random effects. Antecedent moisture effects were modeled by using a combination of the previous season's aggregated conditions and a smoothly varying weighted average of the months or weeks directly preceding the observation. The time lag between the driving antecedent condition and the observed change in leaf δ15N indicates a significant and unobserved process mechanism. Preliminary results suggest a CO2 treatment interaction with the lag effect, indicating a treatment effect on the latent process.

  2. The 15N isotope to evaluate fertilizer nitrogen absorption efficiency by the coffee plant

    Directory of Open Access Journals (Sweden)

    Tatiele A.B. Fenilli

    2007-12-01

    Full Text Available The use of the 15N label for agronomic research involving nitrogen (N cycling and the fate of fertilizer-N is well established, however, in the case of long term experimentation with perennial crops like citrus, coffee and rubber tree, there are still shortcomings mainly due to large plant size, sampling procedures, detection levels and interferences on the system. This report tries to contribute methodologically to the design and development of 15N labeled fertilizer experiments, using as an example a coffee crop fertilized with 15N labeled ammonium sulfate, which was followed for two years. The N of the plant derived from the fertilizer was studied in the different parts of the coffee plant in order to evaluate its distribution within the plant and the agronomic efficiency of the fertilizer application practice. An enrichment of the fertilizer-N of the order of 2% 15N abundance was sufficient to study N absorption rates and to establish fertilizer-N balances after one and two years of coffee cropping. The main source of errors in the estimated values lies in the inherent variability among field replicates and not in the measurements of N contents and 15N enrichments of plant material by mass-spectrometry.O uso do traçador 15N em pesquisas agronômicas que envolvem o ciclo do nitrogênio (N e o destino do N do fertilizante está bem estabelecido, entretanto, para o caso de experimentação com plantas perenes como citrus, café e seringueira, ainda existem limitações devidas ao porte das plantas, à amostragem, aos níveis de detecção e à interferência no sistema. Este estudo procura contribuir metodologicamente no delineamento experimental e no desenvolvimento desse tipo de experimentação, em condições de campo, fazendo uso, por dois anos, do experimento de uma cultura de café adubada com fertilizante marcado com 15N. O N da planta derivado do fertilizante foi estudado nas diferentes partes da planta de café para determinar sua

  3. Water-solvent partition coefficients and Delta Log P values as predictors for blood-brain distribution; application of the Akaike information criterion.

    Science.gov (United States)

    Abraham, Michael H; Acree, William E; Leo, Albert J; Hoekman, David; Cavanaugh, Joseph E

    2010-05-01

    It is shown that log P values for water-alkane or water-cyclohexane partitions, and the corresponding Delta log P values when used as descriptors for blood-brain distribution, as log BB, yield equations with very poor correlation coefficients but very good standard deviations, S from 0.25 to 0.33 log units. Using quite large data sets, we have verified that similar S-values apply to predictions of log BB. A suggested model, based on log P for water-dodecane and water-hexadecane partition coefficients, has 109 data points and a fitted S = 0.254 log units. It is essential to include in the model an indicator variable for volatile compounds, and an indicator variable for drugs that contain the carboxylic group. A similar equation based on water-chloroform partition coefficients has 83 data points and a fitted S = 0.287 log units. We can find no causal connection between these log P values and log BB in terms of correlation or in terms of chemical similarity, but conclude that the log P descriptor will yield excellent predictions of log BB provided that predictions are within the chemical space of the compounds used to set up the model. We also show that model based on log P(octanol) and an Abraham descriptor provides a simple and easy method of predicting log BB with an error of no more than 0.31 log units. We have used the Akaike information criterion to investigate the most economic models for log BB.

  4. δ15N in the turtle grass from the Mexican Caribbean

    Science.gov (United States)

    Talavera-Saenz, A.; Sanchez, A.; Ortiz-Hernandez, M.

    2013-05-01

    Nutrient inputs associated with population growth threaten the integrity of coastal ecosystems. To assess the rapid increase in tourism, we compared the δ15N from Thalassia testudinum collected at sites with different levels of tourism development and population to detect the N inputs of wastewater discharge (WD) along the coast of Quintana Roo. The contributions of nitrogen enriched in 15N are directly related to the increase of WD inputs in areas of high tourism development (Nichupte Lagoon in Cancun, >3 million tourists per year from 2007 to 2011 and 0.7 million of resident population) and decreased towards Bahia Akumal and Tulum (>3 million tourists per year from 2007 to 2011 and 0.15 million of resident population). The δ15N from T. testudinum was significantly lower at Mahahual and Puerto Morelos (about 0.4 million tourists per year in 2007 to 2011 and 0.25 million of resident population) than other the sites. In areas of the lowest development and with tourist activity restricted and small population, such as the Yum Balam Reserve and Sian Ka'an Biosphere Reserve, the δ15N values were in much higher enrichment that Mahahual and Puerto Morelos. Therefore is suggested that Mahahual and Puerto Morelos may be used for baseline isotopic monitoring, over environmental pressure on the reef lagoon ecosystem, where tourist activities and population are growing very slow rate. The anthropogenic N input has the potential to impact, both environmentally and economically, the seagrass meadows and the coral reefs along the coast of Quintana Roo and the Caribbean.

  5. (15)N in tree rings as a bio-indicator of changing nitrogen cycling in tropical forests: an evaluation at three sites using two sampling methods.

    Science.gov (United States)

    van der Sleen, Peter; Vlam, Mart; Groenendijk, Peter; Anten, Niels P R; Bongers, Frans; Bunyavejchewin, Sarayudh; Hietz, Peter; Pons, Thijs L; Zuidema, Pieter A

    2015-01-01

    Anthropogenic nitrogen deposition is currently causing a more than twofold increase of reactive nitrogen input over large areas in the tropics. Elevated (15)N abundance (δ(15)N) in the growth rings of some tropical trees has been hypothesized to reflect an increased leaching of (15)N-depleted nitrate from the soil, following anthropogenic nitrogen deposition over the last decades. To find further evidence for altered nitrogen cycling in tropical forests, we measured long-term δ(15)N values in trees from Bolivia, Cameroon, and Thailand. We used two different sampling methods. In the first, wood samples were taken in a conventional way: from the pith to the bark across the stem of 28 large trees (the "radial" method). In the second, δ(15)N values were compared across a fixed diameter (the "fixed-diameter" method). We sampled 400 trees that differed widely in size, but measured δ(15)N in the stem around the same diameter (20 cm dbh) in all trees. As a result, the growth rings formed around this diameter differed in age and allowed a comparison of δ(15)N values over time with an explicit control for potential size-effects on δ(15)N values. We found a significant increase of tree-ring δ(15)N across the stem radius of large trees from Bolivia and Cameroon, but no change in tree-ring δ(15)N values over time was found in any of the study sites when controlling for tree size. This suggests that radial trends of δ(15)N values within trees reflect tree ontogeny (size development). However, for the trees from Cameroon and Thailand, a low statistical power in the fixed-diameter method prevents to conclude this with high certainty. For the trees from Bolivia, statistical power in the fixed-diameter method was high, showing that the temporal trend in tree-ring δ(15)N values in the radial method is primarily caused by tree ontogeny and unlikely by a change in nitrogen cycling. We therefore stress to account for tree size before tree-ring δ(15)N values can be properly

  6. Observational $\\Delta\

    CERN Document Server

    Hernández, Antonio García; Monteiro, Mário J P F G; Suárez, Juan Carlos; Reese, Daniel R; Pascual-Granado, Javier; Garrido, Rafael

    2015-01-01

    Delta Scuti ($\\delta$ Sct) stars are intermediate-mass pulsators, whose intrinsic oscillations have been studied for decades. However, modelling their pulsations remains a real theoretical challenge, thereby even hampering the precise determination of global stellar parameters. In this work, we used space photometry observations of eclipsing binaries with a $\\delta$ Sct component to obtain reliable physical parameters and oscillation frequencies. Using that information, we derived an observational scaling relation between the stellar mean density and a frequency pattern in the oscillation spectrum. This pattern is analogous to the solar-like large separation but in the low order regime. We also show that this relation is independent of the rotation rate. These findings open the possibility of accurately characterizing this type of pulsator and validate the frequency pattern as a new observable for $\\delta$ Sct stars.

  7. DELTAS: A new Global Delta Sustainability Initiative (Invited)

    Science.gov (United States)

    Foufoula-Georgiou, E.

    2013-12-01

    Deltas are economic and environmental hotspots, food baskets for many nations, home to a large part of the world population, and hosts of exceptional biodiversity and rich ecosystems. Deltas, being at the land-water interface, are international, regional, and local transport hubs, thus providing the basis for intense economic activities. Yet, deltas are deteriorating at an alarming rate as 'victims' of human actions (e.g. water and sediment reduction due to upstream basin development), climatic impacts (e.g. sea level rise and flooding from rivers and intense tropical storms), and local exploration (e.g. sand or aggregates, groundwater and hydrocarbon extraction). Although many efforts exist on individual deltas around the world, a comprehensive global delta sustainability initiative that promotes awareness, science integration, data and knowledge sharing, and development of decision support tools for an effective dialogue between scientists, managers and policy makers is lacking. Recently, the international scientific community proposed to establish the International Year of Deltas (IYD) to serve as the beginning of such a Global Delta Sustainability Initiative. The IYD was proposed as a year to: (1) increase awareness and attention to the value and vulnerability of deltas worldwide; (2) promote and enhance international and regional cooperation at the scientific, policy, and stakeholder level; and (3) serve as a launching pad for a 10-year committed effort to understand deltas as complex socio-ecological systems and ensure preparedness in protecting and restoring them in a rapidly changing environment. In this talk, the vision for such an international coordinated effort on delta sustainability will be presented as developed by a large number of international experts and recently funded through the Belmont Forum International Opportunities Fund. Participating countries include: U.S., France, Germany, U.K., India, Japan, Netherlands, Norway, Brazil, Bangladesh

  8. Retrospective characterization of ontogenetic shifts in killer whale diets via δ13C and δ15N analysis of teeth

    Science.gov (United States)

    Newsome, Seth D.; Etnier, Michael A.; Monson, Daniel H.; Fogel, Marilyn L.

    2009-01-01

    Metabolically inert, accretionary structures such as the dentin growth layers in teeth provide a life history record of individual diet with near-annual resolution. We constructed ontogenetic δ13C and δ15N profiles by analyzing tooth dentin growth layers from 13 individual killer whales Orcinus orca collected in the eastern northeast Pacific Ocean between 1961 and 2003. The individuals sampled were 6 to 52 yr old, representing 2 ecotypes—resident and transient—collected across ~25° of latitude. The average isotopic values of transient individuals (n = 10) are consistent with a reliance on mammalian prey, while the average isotopic values of residents (n = 3) are consistent with piscivory. Regardless of ecotype, most individuals show a decrease in δ15N values of ~2.5‰ through the first 3 yr of life, roughly equivalent to a decrease of one trophic level. We interpret this as evidence of gradual weaning, after which, ontogenetic shifts in isotopic values are highly variable. A few individuals (n = 2) maintained relatively stable δ15N and δ13C values throughout the remainder of their lives, whereas δ15N values of most (n = 11) increased by ~1.5‰, suggestive of an ontogenetic increase in trophic level. Significant differences in mean δ13C and δ15N values among transients collected off California suggest that individuality in prey preferences may be prevalent within this ecotype. Our approach provides retrospective individual life history and dietary information that cannot be obtained through traditional field observations of free-ranging and elusive species such as killer whales, including unique historic ecological information that pre-dates modern studies. By providing insights into individual diet composition, stable isotope analysis of teeth and/or bones may be the only means of evaluating a number of hypothesized historical dietary shifts in killer whales of the northeast Pacific Ocean

  9. Comparison of {sup 15}N- and {sup 13}C-determined parameters of mobility in melittin

    Energy Technology Data Exchange (ETDEWEB)

    Zhu Lingyang [University Indianapolis, Department of Physics, Indiana University Purdue (United States); Prendergast, Franklyn G. [Mayo Foundation, Department of Pharmacology (United States); Kemple, Marvin D. [University Indianapolis, Department of Physics, Indiana University Purdue (United States)

    1998-07-15

    Backbone and tryptophan side-chain mobilities in the 26-residue, cytolytic peptide melittin (MLT) were investigated by {sup 15}N and {sup 13}C NMR. Specifically, inverse-detected {sup 15}N T{sub 1} and steady-state NOE measurements were made at 30 and 51 MHz on MLT at 22 deg. C enriched with {sup 15}N at six amide positions and in the Trp{sup 19} side chain. Both the disordered MLT monomer (1.2 mM peptide at pH 3.6 in neat water) and {alpha}-helical MLT tetramer (4.0 mM peptide at pH 5.2 in 150 mM phosphate buffer) were examined. The relaxation data were analyzed in terms of the Lipari and Szabo model-free formalism with three parameters: {tau}{sub m}, the correlation time for the overall rotation; S{sup 2}, a site-specific order parameter which is a measure of the amplitude of the internal motion; and {tau}{sub e}, a local, effective correlation time of the internal motion. A comparison was made of motional parameters from the {sup 15}N measurements and from {sup 13}C measurements on MLT, the latter having been made here and previously [Kemple et al. (1997) Biochemistry, 36, 1678-1688]. {tau}{sub m} and {tau}{sub e} values were consistent from data on the two nuclei. In the MLT monomer, S{sup 2} values for the backbone N-H and C{alpha}-H vectors in the same residue were similar in value but in the tetramer the N-H order parameters were about 0.2 units larger than the C{alpha}-H order parameters. The Trp side-chain N-H and C-H order parameters, and {tau}{sub e} values were generally similar in both the monomer and tetramer. Implications of these results regarding the dynamics of MLT are examined.

  10. Range expansion of the jumbo squid in the NE Pacific: δ15N decrypts multiple origins, migration and habitat use.

    Science.gov (United States)

    Ruiz-Cooley, Rocio I; Ballance, Lisa T; McCarthy, Matthew D

    2013-01-01

    Coincident with climate shifts and anthropogenic perturbations, the highly voracious jumbo squid Dosidicus gigas reached unprecedented northern latitudes along the NE Pacific margin post 1997-98. The physical or biological drivers of this expansion, as well as its ecological consequences remain unknown. Here, novel analysis from both bulk tissues and individual amino acids (Phenylalanine; Phe and Glutamic acid; Glu) in both gladii and muscle of D. gigas captured in the Northern California Current System (NCCS) documents for the first time multiple geographic origins and migration. Phe δ(15)N values, a proxy for habitat baseline δ(15)N values, confirm at least three different geographic origins that were initially detected by highly variable bulk δ(15)N values in gladii for squid at small sizes (60 cm) converged, indicating feeding in a common ecosystem. The strong latitudinal gradient in Phe δ(15)N values from composite muscle samples further confirmed residency at a point in time for large squid in the NCCS. These results contrast with previous ideas, and indicate that small squid are highly migratory, move into the NCCS from two or more distinct geographic origins, and use this ecosystem mainly for feeding. These results represent the first direct information on the origins, immigration and habitat use of this key "invasive" predator in the NCCS, with wide implications for understanding both the mechanisms of periodic D. gigas population range expansions, and effects on ecosystem trophic structure.

  11. Range expansion of the jumbo squid in the NE Pacific: δ15N decrypts multiple origins, migration and habitat use.

    Directory of Open Access Journals (Sweden)

    Rocio I Ruiz-Cooley

    Full Text Available Coincident with climate shifts and anthropogenic perturbations, the highly voracious jumbo squid Dosidicus gigas reached unprecedented northern latitudes along the NE Pacific margin post 1997-98. The physical or biological drivers of this expansion, as well as its ecological consequences remain unknown. Here, novel analysis from both bulk tissues and individual amino acids (Phenylalanine; Phe and Glutamic acid; Glu in both gladii and muscle of D. gigas captured in the Northern California Current System (NCCS documents for the first time multiple geographic origins and migration. Phe δ(15N values, a proxy for habitat baseline δ(15N values, confirm at least three different geographic origins that were initially detected by highly variable bulk δ(15N values in gladii for squid at small sizes (60 cm converged, indicating feeding in a common ecosystem. The strong latitudinal gradient in Phe δ(15N values from composite muscle samples further confirmed residency at a point in time for large squid in the NCCS. These results contrast with previous ideas, and indicate that small squid are highly migratory, move into the NCCS from two or more distinct geographic origins, and use this ecosystem mainly for feeding. These results represent the first direct information on the origins, immigration and habitat use of this key "invasive" predator in the NCCS, with wide implications for understanding both the mechanisms of periodic D. gigas population range expansions, and effects on ecosystem trophic structure.

  12. Determination of the natural abundance δ15N of taurine by gas chromatography-isotope ratio measurement mass spectrometry.

    Science.gov (United States)

    Tea, Illa; Antheaume, Ingrid; Besnard, Jorick; Robins, Richard J

    2010-12-15

    The measurement of the nitrogen isotope ratio of taurine (2-aminoethanesulphonic acid) in biological samples has a large number of potential applications. Taurine is a small water-soluble molecule which is notoriously difficult to analyze due to its polarity and functionality. A method is described which allows the determination of the natural abundance δ(15)N values of taurine and structural analogues, such as 3-amino-1-propanesulphonic acid (APSA), by isotope ratio mass spectrometry interfaced to gas chromatography (GC-irm-MS). The one-step protocol exploits the simultaneous derivatization of both functionalities of these aminosulphonic acids by reaction with triethylorthoacetate (TEOA). Conditions have been established which ensure quantitative reaction thus avoiding any nitrogen isotope fractionation during derivatization and workup. The differences in the δ(15)N values of derivatized and non-derivatized taurine and APSA all fall within the working range of 0.4‰ (-0.02 to 0.39‰). When applied to four sources of taurine with various δ(15)N values, the method achieved excellent reproducibility and accuracy. The optimized method enables the determination of the natural abundance δ(15)N values of taurine over the concentration range 1.5-7.84 µmol.mL(-1) in samples of biological origin.

  13. Compound-specific 15N stable isotope probing of N assimilation by the soil microbial biomass: a new methodological paradigm in soil N cycling

    Science.gov (United States)

    Charteris, A. F.; Knowles, T. D. J.; Michaelides, K.; Evershed, R. P.

    2015-10-01

    A compound-specific nitrogen-15 stable isotope probing (15N-SIP) technique is described which allows investigation of the fate of inorganic- or organic-N amendments to soils. The technique uses gas chromatography-combustion-isotope ratio mass spectrometry (GC-C-IRMS) to determine the δ15N values of individual amino acids (AAs; determined as N-acetyl, O-isopropyl derivatives) as proxies of biomass protein production. The δ15N values are used together with AA concentrations to quantify N assimilation of 15N-labelled substrates by the soil microbial biomass. The utility of the approach is demonstrated through incubation experiments using inorganic 15N-labelled substrates ammonium (15NH4+) and nitrate (15NO3-) and an organic 15N-labelled substrate, glutamic acid (15N-Glu). Assimilation of all the applied substrates was undetectable based on bulk soil properties, i.e. % total N (% TN), bulk soil N isotope composition and AA concentrations, all of which remained relatively constant throughout the incubation experiments. In contrast, compound-specific AA δ15N values were highly sensitive to N assimilation, providing qualitative and quantitative insights into the cycling and fate of the applied 15N-labelled substrates. The utility of this 15N-AA-SIP technique is considered in relation to other currently available methods for investigating the microbially-mediated assimilation of nitrogenous substrates into the soil organic N pool. This approach will be generally applicable to the study of N cycling in any soil, or indeed, in any complex ecosystem.

  14. The δ15N of nitrate in the Southern Ocean: Consumption of nitrate in surface waters

    Science.gov (United States)

    Sigman, D. M.; Altabet, M. A.; McCorkle, D. C.; Francois, R.; Fischer, G.

    1999-12-01

    We report nitrogen isotope data for nitrate from transects of hydrocast and surface samples collected in the eastern Indian and Pacific sectors of the Southern Ocean, focusing here on the data from the upper water column to study the effect of nitrate consumption by phytoplankton. The δ15N of nitrate increases by 1-2‰ from deep water into the Antarctic summertime surface layer, due to kinetic isotopic fractionation during nitrate uptake. Estimation of the nitrate uptake isotope effect from Antarctic depth profiles yields values in the range of 5-6‰ in east Indian sector and 4-5‰ in the east Pacific sector. Surface transect data from the Pacific sector also yield values of 4-5‰. The major uncertainty in the profile-based estimation of the isotope effect involves the δ15N of nitrate from the temperature minimum layer below the summertime Antarctic surface layer, which deviates significantly from the predictions of simple models of isotope fractionation. For the Subantarctic surface, it is possible to distinguish between nitrate supplied laterally from the surface Antarctic and nitrate supplied vertically from the Subantarctic thermocline because of the distinctive relationships between the δ15N and concentration of nitrate in these two potential sources. Our Subantarctic samples, collected during the summer and fall, indicate that nitrate is supplied to the Subantarctic surface largely by northward transport of Antarctic surface water. Isotopic data from the Pacific sector of the Subantarctic suggest an isotope effect of 4.5‰, indistinguishable from the Antarctic estimates in this sector.

  15. Fate of orally administered {sup 15}N-labeled polyamines in rats bearing solid tumors

    Energy Technology Data Exchange (ETDEWEB)

    Kobayashi, Masaki; Samejima, Keijiro; Goda, Hitomi; Niitsu, Masaru [Josai Univ., Sakado, Saitama (Japan). Faculty of Pharmaceutical Sciences; Xu Yongji [Qingdao Univ. of Science and Technology (China). Inst. of Chemical and Molecular Technology; Takahashi, Masakazu [Sasaki Inst., Tokyo (Japan); Hashimoto, Yoshiyuki [Kyoritsu Coll. of Pharmacy, Tokyo (Japan)

    2003-03-01

    We studied absorption, distribution, metabolism, and excretion of polyamines (putrescine, spermidine, and spermine) in the gastrointestinal tract using {sup 15}N-labeled polyamines as tracers and ionspray ionization mass spectrometry (IS-MS). The relatively simple protocol using rats bearing solid tumors provided useful information. Three {sup 15}N-labeled polyamines that were simultaneously administered were absorbed equally from gastrointestinal tract, and distributed within tissues at various concentrations. The uptake of {sup 15}N-spermidine seemed preferential to that of {sup 15}N-spermine since the concentrations of {sup 15}N-spermidine in the liver and tumors were higher, whereas those of {sup 15}N-spermine were higher in the kidney, probably due to the excretion of excess extracellular spermine. Most of the absorbed {sup 15}N-putrescine seemed to be lost, suggesting blood and tissue diamine oxidase degradation. Concentrations of {sup 15}N-spermidine and {sup 15}N-spermine in the tumor were low. We also describe the findings from two rats that were administered with {sup 15}N-spermine. The tissue concentrations of {sup 15}N-spermine were unusually high, and significant levels of {sup 15}N-spermidine were derived from {sup 15}N-spermine in these animals. (author)

  16. Influence of 15N enrichment on the net isotopic fractionation factor during the reduction of nitrate to nitrous oxide in soil

    DEFF Research Database (Denmark)

    Mathieu, O.; Levegue, J.; Henault, C.

    2007-01-01

    Nitrous oxide, a greenhouse gas, is mainly emitted from soils during the denitrification process. Nitrogen stable-isotope investigations can help to characterise the N(2)O source and N(2)O production mechanisms. The stable-isotope approach is increasingly used with (15)N natural abundance...... or relatively low (15)N enrichment levels and requires a good knowledge of the isotopic fractionation effect inherent to this biological mechanism. This paper reports the measurement of the net and instantaneous isotopic fractionation factor (alpha(i)(s/p)) during the denitrification of NO(3)(-) to N(2)O over...... a range of (15)N substrate enrichments (0.37 to 1.00 atom% (15)N). At natural abundance level, the isotopic fractionation effect reported falls well within the range of data previously observed. For (15)N-enriched substrate, the value of alpha(i)(s/p) was not constant and decreased from 1.024 to 1...

  17. Compound specific amino acid δ15N in marine sediments: A new approach for studies of the marine nitrogen cycle

    Science.gov (United States)

    Batista, Fabian C.; Ravelo, A. Christina; Crusius, John; Casso, Michael A.; McCarthy, Matthew D.

    2014-10-01

    The nitrogen (N) isotopic composition (δ15N) of bulk sedimentary N (δ15Nbulk) is a common tool for studying past biogeochemical cycling in the paleoceanographic record. Empirical evidence suggests that natural fluctuations in the δ15N of surface nutrient N are reflected in the δ15N of exported planktonic biomass and in sedimentary δ15Nbulk. However, δ15Nbulk is an analysis of total combustible sedimentary N, and therefore also includes mixtures of N sources and/or selective removal or preservation of N-containing compounds. Compound-specific nitrogen isotope analyses of individual amino acids (δ15NAA) are novel measurements with the potential to decouple δ15N changes in nutrient N from trophic effects, two main processes that can influence δ15Nbulk records. As a proof of concept study to examine how δ15NAA can be applied in marine sedimentary systems, we compare the δ15NAA signatures of surface and sinking POM sources with shallow surface sediments from the Santa Barbara Basin, a sub-oxic depositional environmental that exhibits excellent preservation of sedimentary organic matter. Our results demonstrate that δ15NAA signatures of both planktonic biomass and sinking POM are well preserved in such surface sediments. However, we also observed an unexpected inverse correlation between δ15N value of phenylalanine (δ15NPhe; the best AA proxy for N isotopic value at the base of the food web) and calculated trophic position. We used a simple N isotope mass balance model to confirm that over long time scales, δ15NPhe values should in fact be directly dependent on shifts in ecosystem trophic position. While this result may appear incongruent with current applications of δ15NAA in food webs, it is consistent with expectations that paleoarchives will integrate N dynamics over much longer timescales. We therefore propose that for paleoceanographic applications, key δ15NAA parameters are ecosystem trophic position, which determines relative partitioning of 15N

  18. Novel Technique for Assessing Ammonium Utilization by Phytoplankton in the San Francisco Bay-Delta Estuary

    Science.gov (United States)

    Schmidt, C. M.; Kendall, C.; Young, M. B.; Kraus, T. E. C.; Silva, S. R.; Richter, M. T.

    2015-12-01

    High concentrations of NH4+ in the San Francisco Bay-Delta Estuary (SFE) have been shown to inhibit the growth of phytoplankton, which are an important food source to zooplankton at the base of the pelagic food web. Here we present results from a study which used a stable isotope mixing model to quantify the proportion of nitrogen assimilated as NH4+ by phytoplankton in situ in a portion of the Sacramento River where NH4+ concentration is elevated downstream of the Sacramento Regional Wastewater Treatment Plant (SRWTP). To determine the δ15N value of phytoplankton, a novel method was developed to isolate phytoplankton from bulk particulate organic matter using flow cytometry prior to isotopic analysis. Modifications were made to an elemental analyzer to allow measurement of the δ15N values of samples containing as little as 0.5 µg N with an analytical precision of 0.2‰ (determined from replicate analysis of standards). During fall and spring field campaigns, two parcels of Sacramento River water (one with wastewater effluent and one without) were tracked and sampled in a Lagrangian sampling scheme over ~80 hours of travel downstream of the SRWTP. Water samples were analyzed for nutrient and chlorophyll concentrations as well δ15N-NO3 and δ15N-NH4+. In addition, approximately ten million phytoplankton cells were sorted from each sample for analysis of δ15N-phytoplankton. In parcels of Sacramento River water without wastewater effluent, NH4+ concentrations remained low and trends in δ15N-phytoplankton followed trends in δ15N-NO3-. In contrast, in the parcels containing SRWTP effluent phytoplankton uptake of N as NH4+ gradually increased from 15% immediately downstream of the SRWTP to as high as 90% after 80 hours of downstream transit. Previous mesocosm incubation experiments have demonstrated depressed growth rates and a rapid switch from NO3- to NH4+ uptake downstream of the SRWTP, suggesting that the apparent gradual increase in the proportion of N

  19. The influence of fish cage culture on δ13C and δ15N of filter-feeding Bivalvia (Mollusca).

    Science.gov (United States)

    Benedito, E; Figueroa, L; Takeda, A M; Manetta, G I

    2013-11-01

    The objective of this study was to evaluate the effect of Oreochromis niloticus cage culture promoted variations in the δ13C and δ15N in Corbicula fluminea (Mollusca; Bivalvia) and in the sediment of an aquatic food web. Samples were taken before and after net cage installation in the Rosana Reservoir (Paranapanema River, PR-SP). Samples of specimens of the bivalve filterer C. fluminea and samples of sediment were collected using a modified Petersen grab. All samples were dried in an oven (60 °C) for 72 hours, macerated to obtain homogenous fine powders and sent for carbon (δ13C) and nitrogen (δ15N) isotopic value analysis in a mass spectrometer. There were significant differences in the δ13C and δ15N values of the invertebrate C. fluminea between the beginning and the end of the experiment. There were no differences between the δ13C and δ15N values of sediment. These results indicate that the installation of fish cage culture promoted impacts in the isotopic composition of the aquatic food web organisms, which could exert influence over the native species and the ecosystem.

  20. Mimicking floodplain reconnection and disconnection using 15N mesocosm incubations

    Directory of Open Access Journals (Sweden)

    W. Wanek

    2012-04-01

    Full Text Available Floodplain restoration changes the nitrate delivery pattern and dissolved organic matter pool in backwaters but other effects are not yet well known. We performed two mesocosm experiments to quantify the nitrate metabolism in two types of floodplains. Rates of denitrification, dissimilatory nitrate reduction to ammonium (DNRA and anammox were measured using 15N tracer additions in mesocosms containing undisturbed floodplain sediments originating from (1 restored and (2 disconnected sites in the Alluvial Zone National Park on the Danube River downstream of Vienna, Austria. DNRA rates were an order of magnitude lower than denitrification and neither rate was affected by changes in nitrate delivery pattern or organic matter quality. Anammox was not detected at any of the sites. Denitrification was out-competed by assimilation which was estimated to use up to 70% of the available nitrate. Overall, denitrification was higher in the restored sites, with mean rates of 5.7±2.8 mmol N m−2 h−1 compared to the disconnected site (0.6±0.5 mmol N m−1 h−1. In addition, ratios of N2O : N2 were lower in the restored site indicating a more complete denitrification. Nitrate addition did not have any effect on denitrification, nor on the N2O : N2 ratio. However, DOM quality significantly changed the N2O : N2 ratio in both sites. Addition of riverine derived organic matter lowered the N2O : N2 ratio in the disconnected site, whereas addition of floodplain derived organic matter increased the N2O : N2 ratio in the restored site. These results demonstrate that increasing floodplains hydrological connection to the main river channel increases nitrogen retention and decreases nitrous oxide emissions.

  1. Regional patterns in foliar 15N across a gradient of nitrogen deposition in the northeastern US

    Science.gov (United States)

    Linda H. Pardo; Steven G. McNulty; Johnny L. Boggs; Sara Duke

    2007-01-01

    Recent studies have demonstrated that natural abundance 15N can be a useful tool for assessing nitrogen saturation, because as nitrification and nitrate loss increase, d15N of foliage and soil also increases. We measured foliar d15N at 11 high-elevation spruce-fir stands along an N deposition gradient...

  2. Organic vs. conventional grassland management: do (15N and (13C isotopic signatures of hay and soil samples differ?

    Directory of Open Access Journals (Sweden)

    Valentin H Klaus

    Full Text Available Distinguishing organic and conventional products is a major issue of food security and authenticity. Previous studies successfully used stable isotopes to separate organic and conventional products, but up to now, this approach was not tested for organic grassland hay and soil. Moreover, isotopic abundances could be a powerful tool to elucidate differences in ecosystem functioning and driving mechanisms of element cycling in organic and conventional management systems. Here, we studied the δ(15N and δ(13C isotopic composition of soil and hay samples of 21 organic and 34 conventional grasslands in two German regions. We also used Δδ(15N (δ(15N plant - δ(15N soil to characterize nitrogen dynamics. In order to detect temporal trends, isotopic abundances in organic grasslands were related to the time since certification. Furthermore, discriminant analysis was used to test whether the respective management type can be deduced from observed isotopic abundances. Isotopic analyses revealed no significant differences in δ(13C in hay and δ(15N in both soil and hay between management types, but showed that δ(13C abundances were significantly lower in soil of organic compared to conventional grasslands. Δδ(15N values implied that management types did not substantially differ in nitrogen cycling. Only δ(13C in soil and hay showed significant negative relationships with the time since certification. Thus, our result suggest that organic grasslands suffered less from drought stress compared to conventional grasslands most likely due to a benefit of higher plant species richness, as previously shown by manipulative biodiversity experiments. Finally, it was possible to correctly classify about two third of the samples according to their management using isotopic abundances in soil and hay. However, as more than half of the organic samples were incorrectly classified, we infer that more research is needed to improve this approach before it can be

  3. Organic vs. conventional grassland management: do (15)N and (13)C isotopic signatures of hay and soil samples differ?

    Science.gov (United States)

    Klaus, Valentin H; Hölzel, Norbert; Prati, Daniel; Schmitt, Barbara; Schöning, Ingo; Schrumpf, Marion; Fischer, Markus; Kleinebecker, Till

    2013-01-01

    Distinguishing organic and conventional products is a major issue of food security and authenticity. Previous studies successfully used stable isotopes to separate organic and conventional products, but up to now, this approach was not tested for organic grassland hay and soil. Moreover, isotopic abundances could be a powerful tool to elucidate differences in ecosystem functioning and driving mechanisms of element cycling in organic and conventional management systems. Here, we studied the δ(15)N and δ(13)C isotopic composition of soil and hay samples of 21 organic and 34 conventional grasslands in two German regions. We also used Δδ(15)N (δ(15)N plant - δ(15)N soil) to characterize nitrogen dynamics. In order to detect temporal trends, isotopic abundances in organic grasslands were related to the time since certification. Furthermore, discriminant analysis was used to test whether the respective management type can be deduced from observed isotopic abundances. Isotopic analyses revealed no significant differences in δ(13)C in hay and δ(15)N in both soil and hay between management types, but showed that δ(13)C abundances were significantly lower in soil of organic compared to conventional grasslands. Δδ(15)N values implied that management types did not substantially differ in nitrogen cycling. Only δ(13)C in soil and hay showed significant negative relationships with the time since certification. Thus, our result suggest that organic grasslands suffered less from drought stress compared to conventional grasslands most likely due to a benefit of higher plant species richness, as previously shown by manipulative biodiversity experiments. Finally, it was possible to correctly classify about two third of the samples according to their management using isotopic abundances in soil and hay. However, as more than half of the organic samples were incorrectly classified, we infer that more research is needed to improve this approach before it can be efficiently

  4. Delta robot

    NARCIS (Netherlands)

    Herder, J.L.; Van der Wijk, V.

    2010-01-01

    The invention relates to a delta robot comprising a stationary base (2) and a movable platform (3) that is connected to the base with three chains of links (4,5,6), and comprising a balancing system incorporating at least one pantograph (7) for balancing the robot's center of mass, wherein the at le

  5. Delta robot

    NARCIS (Netherlands)

    Herder, J.L.; Van der Wijk, V.

    2010-01-01

    The invention relates to a delta robot comprising a stationary base (2) and a movable platform (3) that is connected to the base with three chains of links (4,5,6), and comprising a balancing system incorporating at least one pantograph (7) for balancing the robot's center of mass, wherein the at le

  6. PARTITIONING THE RELATIVE INFLUENCE OF SOIL N, MYCORRHIZAE, AND FOLIAR N UPTAKE ON FOLIAR δ15N PATTERNS: CAN WE DETECT FOLIAR UPTAKE OF REACTIVE N?

    Science.gov (United States)

    Vallano, D.; Sparks, J. P.

    2009-12-01

    Vegetation is an important sink for atmospheric reactive N in N-limited systems and may be capable of incorporating reactive N compounds directly into leaves through the foliar uptake pathway. A proxy for atmospheric reactive N entering vegetation would be useful to estimate the impact of direct foliar N uptake on plant metabolism. Natural abundance foliar N isotopic composition (δ15N) is a practical tool for this purpose because plant-available N sources often have different isotopic compositions. Current understanding of foliar δ15N suggests these values primarily represent the integration of soil δ15N, direct foliar N uptake, mycorrhizal fractionation, and within-plant fractionations. Using a potted plant mesocosm system, we estimated the influence of mycorrhizae on foliar δ15N patterns in red maple (Acer rubrum) seedlings along an N deposition gradient in New York State. We found that mycorrhizal associations altered foliar δ15N in red maple seedlings from 0.03 - 1.01‰ across sites. Along the same temporal and spatial scales, we examined the influence of soil δ15N, foliar N uptake, and mycorrhizae on foliar δ15N in adult stands of American beech (Fagus grandifolia), black birch (Betula lenta), red maple (A. rubrum), and red oak (Quercus rubra). Using multiple regression models, atmospheric NO2 concentration explained 0%, 69%, 23%, and 45% of the residual variation in foliar δ15N remaining in American beech, red maple, red oak, and black birch, respectively, after accounting for soil δ15N. Our results suggest that foliar δ15N may be used to estimate pollution-derived atmospheric reactive N entering vegetation via the foliar N uptake pathway.

  7. Growth, development, and fertilizer-{sup 15}N recovery by the coffee plant

    Energy Technology Data Exchange (ETDEWEB)

    Fenilli, Tatiele Anete Bergamo [Fundacao Universidade Regional de Blumenau (FURB), Blumenau, SC (Brazil). Dept. de Engenharia Florestal; Reichardt, Klaus; Bacchi, Osny Oliveira Santos [Centro de Energia Nuclear na Agricultura (CENA), Piracicaba, SP (Brazil). Lab. de Fisica do Solo]. E-mail: klaus@cena.usp.br; Dourado-Neto, Durval; Favarin, Jose Laercio [Escola Superior de Agricultura Luiz de Queiroz (ESALQ/USP), Piracicaba, SP (Brazil). Dept. de Producao Vegetal; Trivelim, Paulo Cesar Ocheuze [Centro de Energia Nuclear na Agricultura (CENA), Piracicaba, SP (Brazil). Lab. de Isotopos Estaveis; Costa, Flavio Murilo Pereira da [Ministerio do Desenvolvimento Agrario, Brasilia, DF (Brazil). Secretaria de Assuntos Fundiarios - SEAF

    2007-09-15

    The relationship between growth and fertilizer nitrogen recovery by perennial crops such as coffee is poorly understood and improved understanding of such relations is important for the establishment of rational crop management practices. In order to characterize the growth of a typical coffee crop in Brazil and quantify the recovery of {sup 15}N labeled ammonium sulfate, and improve information for fertilizer management practices this study presents results for two consecutive cropping years, fertilized with 280 and 350 kg ha{sup -1} of N, respectively, applied in four splittings, using five replicates. Shoot dry matter accumulation was evaluated every 60 days, separating plants into branches, leaves and fruits. Labeled sub-plots were used to evaluate N-total and {sup 15}N abundance by mass spectrometry. During the first year the aerial part reached a recovery of 71% of the fertilizer N applied up to February, but this value was reduced to 34% at harvest and 19% at the beginning of the next flowering period due to leaf fall and fruit export. For the second year the aerial part absorbed 36% of the fertilizer N up to March, 47% up to harvest and 19% up to the beginning of the next flowering period. The splitting into four applications of the used fertilizer rates was adequate for the requirements of the crop at these growth stages of the coffee crop. (author)

  8. Constraining the S factor of 15N(p,g)16O at Astrophysical Energies

    CERN Document Server

    LeBlanc, P J; Goerres, J; Junker, M; Azuma, R; Beard, M; Bemmerer, D; Best, A; Broggini, C; Caciolli, A; Corvisiero, P; Costantini, H; Couder, M; deBoer, R; Elekes, Z; Falahat, S; Formicola, A; Fulop, Zs; Gervino, G; Guglielmetti, A; Gustavino, C; Gyurky, Gy; Kaeppeler, F; Kontos, A; Kuntz, R; Leiste, H; Lemut, A; Li, Q; Limata, B; Marta, M; Mazzocchi, C; Menegazzo, R; O'Brien, S; Palumbo, A; Prati, P; Roca, V; Rolfs, C; Alvarez, C Rossi; Somorjai, E; Stech, E; Straniero, O; Strieder, F; Tan, W; Terrasi, F; Trautvetter, H P; Uberseder, E; Wiescher, M

    2010-01-01

    The 15N(p,g)16O reaction represents a break out reaction linking the first and second cycle of the CNO cycles redistributing the carbon and nitrogen abundances into the oxygen range. The reaction is dominated by two broad resonances at Ep = 338 keV and 1028 keV and a Direct Capture contribution to the ground state of 16O. Interference effects between these contributions in both the low energy region (Ep < 338 keV) and in between the two resonances (338 15N(p,g)16O reaction has been remeasured covering the energy range from Ep=1800 keV down to 130 keV. The results have been analyzed in the framework of a multi-level R-matrix theory and a S(0) value of 39.6 keV b has been found.

  9. Nonpolar nitrous oxide dimer: fundamentals of the mixed 14N2O-15N2O dimer and new combination bands of (14N2O)2 and (15N2O)2 involving the Bu, intermolecular bend.

    Science.gov (United States)

    Dehghany, M; Afshari, Mahin; Abusara, Z; Moazzen-Ahmadi, N

    2009-09-21

    Spectra of the nonpolar nitrous oxide dimer in the region of the N2O v1 fundamental band are observed in a pulsed supersonic slit jet expansion probed with a tunable diode laser. Four bands are analysed: two fundamentals of the mixed 14N2O-15N2O dimer and combination bands involving the intermolecular disrotation of the monomers (Bu intermolecular bend) for both (14N2O)2 and (15N2O)2. Because the determination of this intermolecular frequency relies on the experimentally unknown frequency of the (forbidden) symmetric fundamental, we used previously published ab initio results and their proximity to our experimental values to assign the upper state of the combination bands. The resulting intermolecular disrotation frequencies are 42.3(1.0) and 41.6(1.0) cm(-1) for the (14N2O)2 and (15N2O)2, respectively. This represents the first observation of the mixed 14N2O-15N2O dimer, and the direct determination of a second intermolecular frequency for the nonpolar (N2O)2.

  10. Differentiation of Pigment in Eggs Using Carbon ((13)C/(12)C) and Nitrogen ((15)N/(14)N) Stable Isotopes.

    Science.gov (United States)

    Sun, Feng M; Shi, Guang Y; Wang, Hui W

    2016-07-01

    Consumers prefer natural and healthy food, but artificial pigments are often abused in egg products. The study aimed at differentiating the origin of pigments in eggs by applying the technique of carbon ((13)C/(12)C) and nitrogen ((15)N/(14)N) stable isotope analysis. Five hundred sixty laying hens were randomly distributed into 14 treatments, which were divided into four groups: maize, carophyll red pigment, carophyll yellow pigment, and a mixture of carophyll red and yellow pigments. Eggs were collected and pretreated to determe the values of the Roche Yolk Color Fan (RCF), δ(13)C, and δ(15)N. With increasing maize content, the RCF and δ(13)C values of yolks increased. Moreover, the RCF values in the three pigment groups were significantly influenced by the artificial colors, but δ(13)C values were not significantly different, regardless of the existence of pigment. The δ(15)N values in all treatments did not vary as regularly as the carbon stable isotope. A strong positive correlation was found between RCF and δ(13)C in the maize group, but no such correlation was be observed in the pigment groups. It is concluded that carbon stable isotope ratio analysis (δ(13)C) of the yolk can be used to differentiate the origin of the pigment added to eggs.

  11. A 115-year δ15N record of cumulative nitrogen pollution in California serpentine grasslands

    Science.gov (United States)

    Vallano, D.; Zavaleta, E. S.

    2010-12-01

    Until the 1980s, California’s biodiverse serpentine grasslands were threatened primarily by development and protected by reserve creation. However, nitrogen (N) fertilization due to increasing fossil fuel emissions in the expanding Bay Area is thought to be contributing to rapid, recent invasion of these ecosystems by exotic annual grasses that are displacing rare and endemic serpentine species. Documenting the cumulative effects of N deposition in this ecosystem can direct policy and management actions to mitigate the role of N deposition in its transformation. Natural abundance stable isotopes of N in vegetation have been increasingly used as bio-indicators of N deposition patterns and subsequent changes to plant N cycling and assimilation. However, the long-term record of atmospheric reactive N enrichment and the resulting changes in ecosystem N dynamics have yet to be adequately reconstructed in many ecosystems. Museum archives of vascular plant tissue are valuable sources of materials to reconstruct temporal and spatial isotopic patterns of N inputs to ecosystems. Here, we present N stable isotope data from archived and current specimens of an endemic California serpentine grassland species, leather oak (Quercus durata), since 1895 across the greater San Francisco Bay region. We measured spatial and temporal trends in stable isotope composition (δ15N and δ13C) and concentration (%N and %C) of historical and current samples of leather oak leaves from sites within the Bay Area, impacted by increasing development, and sites northeast of the Bay Area, with significantly lower rates of urbanization and industrialization. Specifically, we sampled dry museum and fresh leaf specimens from serpentine sites within Lake (n=27) and Santa Clara (n=30) counties dating from 1895 to 2010. Leaf δ15N values were stable from 1895 to the 1950s and then decreased strongly throughout the last 50 years as fossil fuel emissions rapidly increased in the Bay Area, indicating that

  12. Chemical synthesis of glycoproteins with the specific installation of gradient enriched 15N-labeled amino acids for getting insight into glycoprotein behavior.

    Science.gov (United States)

    Kajihara, Yasuhiro; Nguyen, Minh Hien; Izumi, Masayuki; Sato, Hajime; Okamoto, Ryo

    2017-03-09

    We propose a novel partially 15N-labelling method for the amide backbone of a synthetic glycoprotein. By use of a chemical approach utilizing SPPS and NCL, we inserted thirteen 15N-labeled amino acids at specific positions of the protein backbone, while intentionally varying the enrichment of 15N atoms. This idea enables us to discriminate even the same type of amino acid based on the intensities of 1H-15N HSQC signals, thus allowing us to understand the dynamics of the local conformation of a synthetic homogeneous glycoprotein. Results suggested that the attachment of an oligosaccharide of either a bi-antennary complex-type or a high-mannose-type did not disturb protein conformation. However, T1 values suggested that the oligosaccharide influenced dynamics at the local conformation. Temperature-varied CD spectra and T1 values clearly indicated that oligosaccharides appeared to inhibit protein fluctuation or, in other words, stabilize protein structure.

  13. A 15N stable isotope semen label to detect mating in the malaria mosquito Anopheles arabiensis Patton

    Directory of Open Access Journals (Sweden)

    Gludovacz Doris

    2008-07-01

    Full Text Available Abstract In previous studies it was determined that the stable isotope 13-carbon can be used as a semen label to detect mating events in the malaria mosquito Anopheles arabiensis. In this paper we describe the use of an additional stable isotope, 15-nitrogen (15N, for that same purpose. Both stable isotopes can be analysed simultaneously in a mass spectrometer, offering the possibility to detect both labels in one sample in order to study complex and difficult-to-detect mating events, such as multiple mating. 15N-glycine was added to larval rearing water and the target enrichment was 5 atom% 15N. Males from these trays were mated with unlabelled virgin females, and spiked spermathecae were analysed for isotopic composition after mating using mass spectrometry. Results showed that spermathecae positive for semen could be distinguished from uninseminated or control samples using the raw δ15N‰ values. The label persisted in spermathecae for up to 5 days after insemination, and males aged 10 days transferred similar amounts of label as males aged 4 days. There were no negative effects of the label on larval survival and male longevity. Enrichment of teneral mosquitoes after emergence was 4.85 ± 0.10 atom% 15N. A threshold value defined as 3 standard deviations above the mean of virgin (i.e. uninseminated spermathecae samples was successful in classifying a large proportion of samples correctly (i.e. on average 95%. We conclude that alongside 13C, 15N can be used to detect mating in Anopheles and the suitability of both labels is briefly discussed.

  14. Stable isotope tracking of endangered sea turtles: validation with satellite telemetry and δ15N analysis of amino acids.

    Directory of Open Access Journals (Sweden)

    Jeffrey A Seminoff

    Full Text Available Effective conservation strategies for highly migratory species must incorporate information about long-distance movements and locations of high-use foraging areas. However, the inherent challenges of directly monitoring these factors call for creative research approaches and innovative application of existing tools. Highly migratory marine species, such as marine turtles, regularly travel hundreds or thousands of kilometers between breeding and feeding areas, but identification of migratory routes and habitat use patterns remains elusive. Here we use satellite telemetry in combination with compound-specific isotope analysis of amino acids to confirm that insights from bulk tissue stable isotope analysis can reveal divergent migratory strategies and within-population segregation of foraging groups of critically endangered leatherback sea turtles (Dermochelys coriacea across the Pacific Ocean. Among the 78 turtles studied, we found a distinct dichotomy in δ(15N values of bulk skin, with distinct "low δ(15N" and "high δ(15N" groups. δ(15N analysis of amino acids confirmed that this disparity resulted from isotopic differences at the base of the food chain and not from differences in trophic position between the two groups. Satellite tracking of 13 individuals indicated that their bulk skin δ(15N value was linked to the particular foraging region of each turtle. These findings confirm that prevailing marine isoscapes of foraging areas can be reflected in the isotopic compositions of marine turtle body tissues sampled at nesting beaches. We use a Bayesian mixture model to show that between 82 and 100% of the 78 skin-sampled turtles could be assigned with confidence to either the eastern Pacific or western Pacific, with 33 to 66% of all turtles foraging in the eastern Pacific. Our forensic approach validates the use of stable isotopes to depict leatherback turtle movements over broad spatial ranges and is timely for establishing wise conservation

  15. {Delta}I = 3/2 and {Delta}S = 2 Hyperon decays in chiral perturbation theory

    Energy Technology Data Exchange (ETDEWEB)

    He, X.G. [University of Melbourne, Parkville, VIC (Australia). School of Physics; Valencia, G. [Iowa State University, Ames, Iowa (United States). Department of Physics and Astronomy

    1997-05-01

    We study the| {Delta}I| = 3/2 and |{Delta}S| = 2 amplitudes for hyperon decays of the form B {yields} B`{pi} at lowest order in chiral perturbation theory. At this order, the {Delta}I = 3/2 amplitudes depend on only one constant. We extract the value of this constant from experiment and find a reasonable description of these processes within experimental errors. The same constant determines the {Delta}S = 2 transitions which, in the standard model, are too small to be observed. We find that new physics with parity odd {Delta}S = 2 interactions can produce observable rates in hyperon decays while evading the bounds from K{sup 0} - K-bar{sup 0} mixing. (authors) 10 refs., 3 tabs.

  16. Regulation of [15N]urea synthesis from [5-15N]glutamine. Role of pH, hormones, and pyruvate.

    Science.gov (United States)

    Nissim, I; Yudkoff, M; Brosnan, J T

    1996-12-01

    We have utilized both [5-15N]glutamine and [3-13C] pyruvate as metabolic tracers in order to: (i) examine the effect of pH, glucagon (GLU), or insulin on the precursor-product relationship between 15NH3, [15N]citrulline, and, thereby, [15N]urea synthesis and (ii) elucidate the mechanism(s) by which pyruvate stimulates [15N] urea synthesis. Hepatocytes isolated from rat were incubated at pH 6.8, 7.4, or 7.6 with 1 mM [5-15N]glutamine and 0.1 mM 14NH4Cl in the presence or the absence of [3-13C] pyruvate (2 mM). A separate series of experiments was performed at pH 7.4 in the presence of insulin or GLU. 15NH3 enrichment exceeded or was equal to that of [15N]citrulline under all conditions except for pH 7.6, when the 15N enrichment in citrulline exceeded that in ammonia. The formation of [15N]citrulline (atom % excess) was increased with higher pH. Flux through phosphate-dependent glutaminase (PDG) and [15N]urea synthesis were stimulated (p < 0.05) at pH 7.6 or with GLU and decreased (p < 0.05) at pH 6.8. Insulin had no significant effect on flux through PDG or on [15N]urea synthesis. Decreased [15N]urea production at pH 6.8 was associated with depleted aspartate and glutamate levels. Pyruvate attenuated this decrease in the aspartate and glutamate pools and stimulated [15N]urea synthesis. Production of Asp from pyruvate was increased with increasing medium pH. Approximately 80% of Asp was derived from [3-13C]pyruvate regardless of incubation pH or addition of hormone. Furthermore, approximately 20, 40, and 50% of the mitochondrial N-acetylglutamate (NAG) pool was derived from [3-13C]pyruvate at pH 6.8, 7.4, and 7.6, respectively. Both the concentration and formation of [13C]NAG from [3-13C]pyruvate were increased (p < 0.05) with glucagon and decreased (p < 0.05) with insulin or at pH 6.8. The data suggest a correlation between changes in [15N]urea synthesis and alterations in the level and synthesis of [13C]NAG from pyruvate. The current observations suggest that the

  17. Radiocarbon, 13C and 15N analysis of fossil bone: Removal of humates with XAD-2 resin

    Science.gov (United States)

    Stafford, Thomas W., Jr.; Brendel, Klaus; Duhamel, Raymond C.

    1988-09-01

    Humic acids are the predominant source of error in the 14C and stable isotope analysis of fossil bone organic matter. XAD-2 resin will quantitatively remove humates and give the highest yields of protein from bones with variable types of preservation. Decalcified bone, gelatin and base-leached residues can vary up to 5%. for δ 13C and by 1%. on δ 15N relative to XAD-treated fractions. Simultaneous analysis of 14C age, δ 13C and δ 15N is recommended because each isotope value can be independently affected by the bone's diagenetic history. Radiocarbon analysis is the most sensitive and δ 15N is least sensitive for detecting exogenous organic matter. The uncertainty of analyses on the best pretreated protein is ±0.5%. for both δ 13C and δ 15N and is larger than previous estimates. The accuracy for all isotope analyses will be better assessed by using individual amino acids instead of total collagenous residues. Inaccurate 14C dates on severely degraded bone are an indication that this class of fossils may be unsuitable for any isotopic analysis.

  18. Production of 15N-Labelled Liquid Organic Fertilisers Based on Manure and Crop Residue for Use in Fertigation Studies.

    Science.gov (United States)

    Martínez-Alcántara, Belén; Martínez-Cuenca, Mary-Rus; Fernández, Carlos; Legaz, Francisco; Quiñones, Ana

    2016-01-01

    Large quantities of crop residue and animal manure from agricultural and livestock activities are annually produced worldwide. With proper management, these residues are potentially valuable sources of plant nutrients, mainly N. Recycling such subproducts in sustainably-based agricultural systems can minimise the use of mineral fertilisers, and hence reduce the potential risk of surface and groundwater pollution. Therefore, the purpose of this study was to obtain (small scale) two liquid labelled-organic fertilisers, an animal- and a vegetal-based organic (AO and VO, respectively) fertiliser, to be used as organic N sources in subsequent fertigation studies. Forage maize (Zea mays L.) grown under 15N-labelled fertiliser supply was used as raw material for VO fertiliser production, and also as 15N-labelled sheep feed to obtain 15N-labelled manure. The labelled faeces fraction was used as raw material for the AO fertiliser. The VO fertiliser was obtained after an acidic and an enzyme-driven hydrolysis. The AO fertiliser was obtained after acidic hydrolysis. The VO liquid fertiliser presented an N concentration of 330 mg·L-1, 85% of total N was organic, while ammonium and nitrate N accounted for 55% and 45% of the mineral nitrogen fraction, respectively. This fertiliser also exhibited high K, Ca and S concentrations and notable values for the remaining macro- and micronutrients. The AO liquid fertiliser had a similar total N concentration (496 mg·L-1, 82% of total N in an organic form) to that of VO, but its mineral N fraction significantly differed, which came in a predominantly (95%) ammonia form. It also had a high content of N, P, K and other macronutrients, and sufficient Fe, Zn, Mn, Cu and B levels, which suggests its suitability as a potential fertiliser. The percentage of 15N enrichment in both VO and AO liquid fertilisers exceeded 2% 15N atom excess, which enabled their use in subsequent assays run to assess nitrogen uptake efficiency.

  19. Nitrogen-containing compounds in two CR2 meteorites: 15N composition, molecular distribution and precursor molecules

    Science.gov (United States)

    Pizzarello, Sandra; Holmes, William

    2009-04-01

    Amino acids, amines and aldehydes were obtained from the water extracts of two CR2 carbonaceous chondrites from Antarctica and analyzed for their molecular and 15N isotopic content. These compounds were found to differ significantly from those of CM chondrites in both overall abundances and molecular distribution. The amino acids suites comprise a preponderant abundance of linear, 2-H amino acids, show rapid non-linear decrease with the compounds' increasing chain length and include protein amino acids never identified in meteorites before, such as threonine, tyrosine and phenylalanine. The presence of tertiary amines as well as a diverse, large abundance of aldehydes and ketones also distinguishes both CR2 organic suites. The δ 15N values determined for CR2 amino acids have a distribution between molecular subgroups that is opposite to the one of their δD values, with 2-H amino acids having higher δ 15N and lower δD values than 2-methyl amino acids, while the opposite is true for 2-methyl amino acids. Based on theoretical data, these isotopic findings would place the formation of the two amino acid groups or their direct precursors at different ISM stages of star formation.

  20. Through-space (19) F-(15) N couplings for the assignment of stereochemistry in flubenzimine.

    Science.gov (United States)

    Ghiviriga, Ion; Rubinski, Miles A; Dolbier, William R

    2016-07-01

    Through-space (19) F-(15) N couplings revealed the configuration of flubenzimine, with the CF3 group on N4 pointing towards the lone pair of N5. The (19) F-(15) N coupling constants were measured at natural abundance using a spin-state selective indirect-detection pulse sequence. As (15) N-labelled proteins are routinely synthesized for NMR studies, through-space (19) F-(15) N couplings have the potential to probe the stereochemistry of these proteins by (19) F labelling of some amino acids or can reveal the site of docking of fluorine-containing drugs. Copyright © 2016 John Wiley & Sons, Ltd.

  1. 基于遥感的辽河三角洲湿地生态系统服务价值评估%Value evaluation on ecosystem function of wetland in Liaohe River Delta

    Institute of Scientific and Technical Information of China (English)

    索安宁; 赵冬至; 卫宝泉; 陈艳拢

    2009-01-01

    利用中巴资源卫星对辽河三角洲盘锦湿地类型进行调查的基础上,综合应用环境经济学、资源经济学等方法对辽河三角洲湿地生态系统的服务功能价值进行了评估,得出该区域湿地生态系统的服务功能总价值为90.243×108元RMB.休闲娱乐、大气组分调节、物质生产和水文调节是该区域湿地生态系统服务功能价值的主要贡献者,分别占到系统总服务功能价值的25.93%、25.03%、22.35%和20.44%.%The main Liaohe River Delta is a wetland ecosystem, including the reef swamp, paddy field, mud flat, river, crab and shrimp field, barren mud and met meadow act surveyed by the remote sensing images of China-Brazil resource satellite. The evaluation on the main services in the wetland ecosystem of Liaohe River Delta was done by methods of environmental economics, resource economics, engineer building value and tour value. The total value in the wetland ecosystem services of Liaohe River Delta is about 90.243×108RMB. Among these services, the order of service value is: material output > air ingredients control > leisure service > flood control > habituating protection > culture service > pollution purification, with contribution of 25.93, 25.03, 22.35, 20.44, 3.17, 1.71 and 1.37%, respectively.

  2. δ15N constraints on long-term nitrogen balances in temperate forests

    Science.gov (United States)

    Perakis, S.S.; Sinkhorn, E.R.; Compton, J.E.

    2011-01-01

    Biogeochemical theory emphasizes nitrogen (N) limitation and the many factors that can restrict N accumulation in temperate forests, yet lacks a working model of conditions that can promote naturally high N accumulation. We used a dynamic simulation model of ecosystem N and δ15N to evaluate which combination of N input and loss pathways could produce a range of high ecosystem N contents characteristic of forests in the Oregon Coast Range. Total ecosystem N at nine study sites ranged from 8,788 to 22,667 kg ha−1 and carbon (C) ranged from 188 to 460 Mg ha−1, with highest values near the coast. Ecosystem δ15N displayed a curvilinear relationship with ecosystem N content, and largely reflected mineral soil, which accounted for 96–98% of total ecosystem N. Model simulations of ecosystem N balances parameterized with field rates of N leaching required long-term average N inputs that exceed atmospheric deposition and asymbiotic and epiphytic N2-fixation, and that were consistent with cycles of post-fire N2-fixation by early-successional red alder. Soil water δ15NO3 − patterns suggested a shift in relative N losses from denitrification to nitrate leaching as N accumulated, and simulations identified nitrate leaching as the primary N loss pathway that constrains maximum N accumulation. Whereas current theory emphasizes constraints on biological N2-fixation and disturbance-mediated N losses as factors that limit N accumulation in temperate forests, our results suggest that wildfire can foster substantial long-term N accumulation in ecosystems that are colonized by symbiotic N2-fixing vegetation.

  3. δ15N constraints on long-term nitrogen balances in temperate forests.

    Science.gov (United States)

    Perakis, Steven S; Sinkhorn, Emily R; Compton, Jana E

    2011-11-01

    Biogeochemical theory emphasizes nitrogen (N) limitation and the many factors that can restrict N accumulation in temperate forests, yet lacks a working model of conditions that can promote naturally high N accumulation. We used a dynamic simulation model of ecosystem N and δ(15)N to evaluate which combination of N input and loss pathways could produce a range of high ecosystem N contents characteristic of forests in the Oregon Coast Range. Total ecosystem N at nine study sites ranged from 8,788 to 22,667 kg ha(-1) and carbon (C) ranged from 188 to 460 Mg ha(-1), with highest values near the coast. Ecosystem δ(15)N displayed a curvilinear relationship with ecosystem N content, and largely reflected mineral soil, which accounted for 96-98% of total ecosystem N. Model simulations of ecosystem N balances parameterized with field rates of N leaching required long-term average N inputs that exceed atmospheric deposition and asymbiotic and epiphytic N(2)-fixation, and that were consistent with cycles of post-fire N(2)-fixation by early-successional red alder. Soil water δ(15)NO(3)(-) patterns suggested a shift in relative N losses from denitrification to nitrate leaching as N accumulated, and simulations identified nitrate leaching as the primary N loss pathway that constrains maximum N accumulation. Whereas current theory emphasizes constraints on biological N(2)-fixation and disturbance-mediated N losses as factors that limit N accumulation in temperate forests, our results suggest that wildfire can foster substantial long-term N accumulation in ecosystems that are colonized by symbiotic N(2)-fixing vegetation.

  4. δ13C and δ15N of moss Haplocladium microphyllum (Hedw.) Broth. for indicating growing environment variation and canopy retention on atmospheric nitrogen deposition

    Science.gov (United States)

    Liu, Xue-Yan; Xiao, Hua-Yun; Liu, Cong-Qiang; Li, You-Yi

    Mosses have been recognized as a useful tool for biomonitoring atmospheric deposition and assessing regional environment. This study was carried on whether the same moss growing in areas with identical regional atmospheric deposition while under different growing environments would have the same indicating signals. Similar variations in mean δ13C and δ15N signatures were found between mosses collected from five habitats, with an increasing sequence from mosses under canopies to epilithic mosses, indicating that habitats were potentially regulating δ13C and δ15N values of mosses. Dryer habitats (lower water availability) and input of more aerosol N were the main reasons for higher δ13C and δ15N values of mosses at open sites (especially for epilithic species), while more negative values of mosses under canopies were attributed to their wetter habitats and less uptake of aerosol N. Additionally, δ15N values not δ13C varied linearly with canopy thickness from -7.84‰ (1 m) to -4.71±0.7‰ (4 m), suggesting δ15N was more sensitive for indicating canopy retention. Consequently, isotopic data of mosses under different environments could not be compared for atmospheric deposition research with each other even collected at the same site. Moss δ13C and δ15N were affected not only by regional atmospheric N sources but also by their growing environments. δ15N of epilithic Haplocladium microphyllum at open sites can be taken as confident bio-indicator of atmospheric N deposition, which would deepen the application of stable nitrogen isotope of bryophytes in atmosphere-plant system study.

  5. Sources and Cycling of Dissolved Organic Matter in the Sacramento - San Joaquin Delta, California, Using Carbon, Nitrogen, and Sulfur Isotopes

    Science.gov (United States)

    Silva, S. R.; Kendall, C.; Doctor, D. H.; Bergamaschi, B. A.; Fram, M. S.; Kraus, T.

    2006-12-01

    An important water quality concern of the Sacramento-San Joaquin Delta portion of the Calfed Bay-Delta restoration program is the generation of disinfection byproducts (DBP) as a result of chlorination or ozonation of San Francisco Bay Delta drinking water. One means of reducing DBPs is through monitoring and control of water sources from the various delta environments entering the California aqueduct with the objective of reducing the quantity of dissolved organic matter (DOM) and lowering the fraction with the highest DBP formation potential. The purpose of this study is to investigate the use of carbon, nitrogen, and sulfur isotopic compositions of DOM to help differentiate DOM sources and interpret seasonal variations. For this purpose, water samples collected from five general delta environments between December 1999 and June 2001 were analyzed for d13C, d15N, and d34S of DOM as well as for various chemical and optical properties. Monthly averages of d13C and d15N values for DOM retained on XAD-4 and XAD-8 resins show distinctive compositions for island drain and wetland environments throughout the year which reflect the agriculturally- related terrestrial sources of DOM from island drains, and the aquatic sources for the wetland areas. On average, the d13C values of DOM from open water (flooded island) environments, channels, and the Sacramento River water are indistinguishable from each other from spring through fall and show a progressive increase in d13C, which is likely controlled by the cycle of aquatic production through the growing season. The isotopic values from these environments diverge in the winter reflecting a change in the relative importance of the various mechanisms (sources and cycling) controlling DOM production. Sulfur isotopes show both the effects of sulfate reduction and the influence of seawater sulfate on local biota. The d13C, d15N, and d34S values show a number of correlations related to both environment and season, reflecting the

  6. A fast method to prepare water samples for 15N analysis

    Institute of Scientific and Technical Information of China (English)

    肖化云; 刘丛强

    2001-01-01

    Automatic element analyser is often used to prepare organic matters tor 15N analysis. It is seldom used to prepare water samples. Water samples are conventionally dealt with by Kjeldahl-Rittenberg technique. But it requires tedious and labor-intensive sample preparation. A fast and reliable method is proposed in this paper to prepare water samples for 15N analysis.

  7. Tracking wind-dispersed seeds using (15)N-isotope enrichment.

    Science.gov (United States)

    Forster, C; Herrmann, J D

    2014-11-01

    Seed dispersal influences a wide range of ecological processes. However, measuring dispersal patterns, particularly long-distance dispersal, has been a difficult task. Marking bird-dispersed seeds with stable (15)N isotopes has been shown to be a user-friendly method to trace seed dispersal. In this study, we determined whether (15)N urea solution could be used to enrich seeds of two common wind-dispersed plants, Eupatorium glaucescens (Asteraceae) and Sericocarpus tortifolius (Asteraceae). We further tested if the water type (distilled versus tap) in (15)N urea solutions influences the level and variability of enrichment of plant seeds, and if increasing spraying frequency per se increases enrichment. Because droughts may lower seed set or kill plants, we wanted to investigate if the additional use of an externally applied anti-transpirant affects the intake of externally applied (15)N into seeds. The results demonstrate that (15)N enrichment of seeds can facilitate dispersal experiments with wind-dispersed plants. The use of distilled water in (15)N urea solutions did not increase (15)N enrichment compared to tap water. Further, enrichment was more efficient at lower spray frequencies. Both the use of tap water and low frequencies could lower time, effort and project costs. The results suggest that species can be protected from drought using an anti-transpirant without decreasing the incorporation of (15)N into seeds. © 2014 German Botanical Society and The Royal Botanical Society of the Netherlands.

  8. An optimized method for (15)N R(1) relaxation rate measurements in non-deuterated proteins.

    Science.gov (United States)

    Gairí, Margarida; Dyachenko, Andrey; González, M Teresa; Feliz, Miguel; Pons, Miquel; Giralt, Ernest

    2015-06-01

    (15)N longitudinal relaxation rates are extensively used for the characterization of protein dynamics; however, their accurate measurement is hindered by systematic errors. (15)N CSA/(1)H-(15)N dipolar cross-correlated relaxation (CC) and amide proton exchange saturation transfer from water protons are the two main sources of systematic errors in the determination of (15)N R1 rates through (1)H-(15)N HSQC-based experiments. CC is usually suppressed through a train of 180° proton pulses applied during the variable (15)N relaxation period (T), which can perturb water magnetization. Thus CC cancellation is required in such a way as to minimize water saturation effects. Here we examined the level of water saturation during the T period caused by various types of inversion proton pulses to suppress CC: (I) amide-selective IBURP-2; (II) cosine-modulated IBURP-2; (III) Watergate-like blocks; and (IV) non-selective hard. We additionally demonstrate the effect of uncontrolled saturation of aliphatic protons on (15)N R1 rates. In this paper we present an optimized pulse sequence that takes into account the crucial effect of controlling also the saturation of the aliphatic protons during (15)N R1 measurements in non-deuterated proteins. We show that using cosine-modulated IBURP-2 pulses spaced 40 ms to cancel CC in this optimized pulse program is the method of choice to minimize systematic errors coming from water and aliphatic protons saturation effects.

  9. Creating 13C- and 15N-enriched tree leaf litter for decomposition experiments

    Science.gov (United States)

    Szlavecz, K. A.; Pitz, S.; Chang, C.; Bernard, M.

    2013-12-01

    Labeling plant material with heavy isotopes of carbon and nitrogen can produce a traceable nutrient signal that can be followed into the different trophic levels and decomposer food web. We treated 60 tree saplings with 13C-enriched CO2 gas and 15N-enriched ammonium nitrate over a three-month period to create dually-labeled plant material for future decomposition experiments. The trees included both early (Red maple, Sweetgum, Tulip poplar) and late (American beech, White oak) successional deciduous tree species, and a conifer, White pine. We constructed a 2.4 m × 2.4 m × 2.4 m environmental chamber that was climate-controlled using an air conditioning system. An Arduino microcontroller interfaced with a Vaisala GMP343 CO2 probe maintained a CO2 concentration between 500-520 ppm by controlling a solenoid valve on the CO2 tank regulator. The trees were placed into the chamber in August 2012 and remained until senescence unless they were lost to death or disease. Ammonium nitrate was added twice, in September and October. Leaf samples were collected prior to the start of the experiment and after senescence, whereas root samples were collected only in December. Samples were dried, ground and analyzed using an isotope ratio mass spectrometer. American beech and White oak had 40% mortality, and 34% of tulip poplar trees were removed because of powdery mildew overgrowth or death. Most tulip poplar trees exhibited a second leaf out following senescence in late September. Nearly 1 kg of litter was produced with tulip poplar representing over half of the total mass. Levels of enrichment varied greatly by species. Beech (-14.2‰) and White oak (-4.8‰) had low levels of enrichment in comparison to early successional species such as Sweetgum (41.7‰) and Tulip poplar (30.7‰ [first leaf fall] and 238.0‰ [second leaf fall]). Leaf enrichment with 15N followed a similar pattern, though it was achieved at a higher level with δ15N values varying from 271.6‰ to 1354.2

  10. Determining the source of nitrate pollution in the Niger discontinuous aquifers using the natural {15N }/{14N } ratios

    Science.gov (United States)

    Girard, Pierre; Hillaire-Marcel, Claude

    1997-12-01

    In the semi-arid Niamey area (Niger), more than 10% of the deep wells exploiting the fracture network of the Precambrian aquifer are contaminated by nitrates, with concentrations as high as 10 meq l -1. In order to identify the source(s) of this pollution, nitrate and 15N contents in the polluted wells were monitored over a 20-month period. Potential sources of nitrate contamination were also analyzed for their 15N content. The isotopic compositions of nitrate in polluted waters were > + 12‰ and in rare cases exceeded +17‰. Latrines (˜ + 15‰) may be the major nitrate source for wells showing δ15N values above +15‰. Below this value, waters may be polluted by a combination of nitrates from both latrine and soil sources (˜ + 10‰). In some cases, the soil may account for up to 85% of the groundwater nitrate load. This mode of groundwater pollution is thought to be a consequence of deforestation. Despite their reputation as polluting agents, fertilizers ( +0.5 < δ 15N < + 3.6‰ ) which are used in rice paddies close to the contaminated areas, do not appear to be a significant source of nitrate contamination. Denitrification is probably not a significant process in the study area. Results suggest that nitrate contamination of the aquifer is a consequence of unregulated urbanization (home-made latrines) and deforestation. While latrines are limited to the urban zones, intensive cutting of the forest to meet the city dwellers' wood demand occurs in an ever increasing area around the capital, threatening the local water supply.

  11. Abundance of 13C and 15N in emmer, spelt and naked barley grown on differently manured soils: towards a method for identifying past manuring practice

    DEFF Research Database (Denmark)

    Kanstrup, Marie; Thomsen, Ingrid Kaag; Andersen, Astrid Junker

    2011-01-01

    The shortage of plant-available nutrients probably constrained prehistoric cereal cropping but there is very little direct evidence relating to the history of ancient manuring. It has been shown that the long-term addition of animal manure elevates the δ15N value of soil and of modern crops grown...... on the soil. We have examined the δ15N and δ13C values of soil and of the grain and straw fractions of three ancient cereal types grown in unmanured, PK amended and cattle manured plots of the Askov long-term field experiment. Manure increased biomass yields and the δ15N values of soil and of grain and straw....... Grain weights differed among cereal types but increased in the order: unmanured, PK, and animal manure. The grain and straw total-N concentration was generally not affected by manure addition. Our study suggests that long-term application of manure to permanently cultivated sites would have provided...

  12. Estimate of production of gaseous nitrogen in the human body based on (15)N analysis of breath N2 after administration of [(15)N2]urea.

    Science.gov (United States)

    Junghans, Peter

    2013-01-01

    After oral administration of [(15)N2]urea (1.5 mmol, 95 atom% (15)N), we found that breath N2 was significantly (15)N-labelled. The result suggests that molecular nitrogen in breath must be partly produced endogenously. Based on a metabolic model, the endogenous N2 production was estimated to be 0.40±0.25 mmol kg(-1) d(-1) or 2.9±1.8 % of the total (urinary and faecal) N excretion in fasted healthy subjects (n=4). In patients infected with Helicobacter pylori (n=5), the endogenous N2 production was increased to 1.24±0.59 mmol kg(-1) d(-1) or 9.0±4.3 % of the total N excretion compared to the healthy controls (pstress-related diseases such as H. pylori infections.

  13. Syntheses of 15N-labeled pre-queuosine nucleobase derivatives

    Directory of Open Access Journals (Sweden)

    Jasmin Levic

    2014-08-01

    Full Text Available Pre-queuosine or queuine (preQ1 is a guanine derivative that is involved in the biosynthetic pathway of the hypermodified tRNA nucleoside queuosine (Que. The core structure of preQ1 is represented by 7-(aminomethyl-7-deazaguanine (preQ1 base. Here, we report the synthesis of three preQ1 base derivatives with complementary 15N-labeling patterns, utilizing [15N]-KCN, [15N]-phthalimide, and [15N3]-guanidine as cost-affordable 15N sources. Such derivatives are required to explore the binding process of the preQ1 base to RNA targets using advanced NMR spectroscopic methods. PreQ1 base specifically binds to bacterial mRNA domains and thereby regulates genes that are required for queuosine biosynthesis.

  14. 1H and 15N Dynamic Nuclear Polarization Studies of Carbazole

    Energy Technology Data Exchange (ETDEWEB)

    Hu, Jian Zhi; Solum, Mark S.; Wind, Robert A.; Nilsson, Brad L.; Peterson, Matt A.; Pugmire, Ronald J.; Grant, David M.

    2000-01-01

    15N NMR experiments, combined with dynamic nuclear polarization (DNP), are reported on carbazole doped with the stable free radical 1,3 bisdiphenylene-2 phenylally1 (BDPA). Doping shortens the nuclear relaxation times and provides paramagnetic centers that can be used to enhance the nuclear signal by means of DNP so that 15 N NMR experiments can be done in minutes. The factors were measured in a 1.4 T external field, using both unlabeled and 98% 15N labeled carbazole with doping levels varying between 0.65 and 5.0 wt % BDPA. A doping level of approximately 1 wt % produced optimal results. DNP enhancement factors of 35 and 930 were obtained for 1H and 15N, respectively making it possible to perform 15N DNP NMR experiments at the natural abundance level.

  15. The impact of the pi-electron conjugation on (15)N, (13)C and (1)H NMR chemical shifts in push-pull benzothiazolium salts. Experimental and theoretical study.

    Science.gov (United States)

    Hrobárik, Peter; Horváth, Branislav; Sigmundová, Ivica; Zahradník, Pavol; Malkina, Olga L

    2007-11-01

    The (15)N as well as (13)C and (1)H chemical shifts of eight push-pull benzothiazolium iodides with various pi-conjugated chains between dimethylamino group and benzothiazolium moiety have been determined by NMR spectroscopy at the natural-abundance level of all nuclei in DMSO-d(6) solution. In general, the quaternary benzothiazolium nitrogen is more shielded [delta((15)N-3) vary between - 241.3 and - 201.9 ppm] with respect to parent 3-methylbenzothiazolium iodide [delta((15)N-3) = - 183.8 ppm], depending on the length and constitution of the pi-conjugated bridge. A larger variation in (15)N chemical shifts is observed on dimethylamino nitrogen, which covers the range of - 323.3 to - 257.2 ppm. The effect of pi-conjugation degree has a less pronounced influence on (13)C and (1)H chemical shifts. Experimental data are interpreted by means of density functional theory (DFT) calculations. Reasonable agreement between theoretical and experimental (15)N NMR chemical shifts was found, particularly when performing calculations with hybrid exchange-correlation functionals. A better accord with experiment is achieved by utilizing a polarizable continuum model (PCM) along with an explicit treatment of hydrogen-bonding between the solute and the water present in dimethylsulfoxide (DMSO). Finally, (13)C and (1)H NMR spectra were computed and analysed in order to compare them with available experimental data. (c) 2007 John Wiley & Sons, Ltd.

  16. Periodicity in Delta-modulated feedback control

    Institute of Scientific and Technical Information of China (English)

    Xiaohua XIA; Guanrong CHEN; Rudong GAI; Alan S. I. ZINOBER

    2008-01-01

    The Delta-modulated feedback control of a linear system introduces nonlinearity into the system through switchings between two input values. It has been found that Delta-modulation gives rise to periodic orbits. The existence of periodic points of all orders of Sigma-Delta modulation with "leaky" integration is completely characterized by some interesting groups of polynomials with "sign" coefficients. The results are naturally generalized to Sigma-Delta modulations with multiple delays, Delta-modulations in the "downlink", unbalanced Delta-modulations and systems with two-level quantized feedback. Further extensions relate to the existence of periodic points arising from Delta-modulated feedback control of a stable linear system in an arbitrary direction, for which some necessary and sufficient conditions are given.

  17. Plot-size for {sup 15}N-fertilizer recovery studies by tanzania-grass; Tamanho da parcela para estudos de recuperacao de fertilizante-{sup 15}N por capim-tanzania

    Energy Technology Data Exchange (ETDEWEB)

    Martha Junior, Geraldo Bueno [EMBRAPA Cerrados, Planaltina, DF (Brazil)], e-mail: gbmartha@cpac.embrapa.br; Trivelin, Paulo Cesar Ocheuze [Centro de Energia Nuclear na Agricultura (CENA/USP), Piracicaba, SP (Brazil). Lab. de Isotopos Estaveis], e-mail: pcotrive@cena.usp.br; Corsi, Moacyr [Escola Superior de Agricultura Luiz de Queiroz (ESALQ/USP), Piracicaba, SP (Brazil). Dept. de Zootecnia], e-mail: moa@esalq.usp.br

    2009-07-01

    The understanding of the N dynamics in pasture ecosystems can be improved by studies using the {sup 15}N tracer technique. However, in these experiments it must be ensured that the lateral movement of the labeled fertilizer does not interfere with the results. In this study the plot-size requirements for {sup 15}N-fertilizer recovery experiments with irrigated Panicum maximum cv. Tanzania was determined. Three grazing intensities (light, moderate and intensive grazing) in the winter, spring and summer seasons were considered. A 1 m{sup 2} plot-size, with a grass tussock in the center, was adequate, irrespective of the grazing intensity or season of the year. Increasing the distance from the area fertilized with {sup 15}N negatively affected the N derived from fertilizer (Npfm) recovered in herbage.The lowest decline in Npfm values were observed for moderate and light grazing intensities. This fact might be explained by the vigorous growth characteristics of these plants. Increasing the grazing intensity decreased the tussock mass and, the smaller the tussock mass, the greater was the dependence on fertilizer nitrogen. (author)

  18. hNCOcanH pulse sequence and a robust protocol for rapid and unambiguous assignment of backbone ((1)H(N), (15)N and (13)C') resonances in (15)N/(13)C-labeled proteins.

    Science.gov (United States)

    Kumar, Dinesh; Hosur, Ramakrishna V

    2011-09-01

    A three-dimensional nuclear magnetic resonance (NMR) pulse sequence named as hNCOcanH has been described to aid rapid sequential assignment of backbone resonances in (15)N/(13)C-labeled proteins. The experiment has been derived by a simple modification of the previously described HN(C)N pulse sequence [Panchal et al., J. Biomol. NMR 20 (2001) 135-147]; t2 evolution is used to frequency label (13)C' rather than (15)N (similar trick has also been used in the design of hNCAnH pulse sequence from hNcaNH [Frueh et al., JACS, 131 (2009) 12880-12881]). The modification results in a spectrum equivalent to HNCO, but in addition to inter-residue correlation peaks (i.e. Hi , Ci-1), the spectrum also contains additional intra-residue correlation peaks (i.e. Hi-1 , Ci-1) in the direct proton dimension which has maximum resolution. This is the main strength of the experiment and thus, even a small difference in amide (1) H chemical shifts (5-6 Hz) can be used for establishing a sequential connectivity. This experiment in combination with the HNN experiment described previously [Panchal et al., J. Biomol. NMR 20 (2001) 135-147] leads to a more robust assignment protocol for backbone resonances ((1) H(N) , (15)N) than could be derived from the combination of HNN and HN(C)N experiments [Bhavesh et al., Biochemistry, 40 (2001) 14727-14735]. Further, this new protocol enables assignment of (13)C' resonances as well. We believe that the experiment and the protocol presented here will be of immense value for structural-and functional-proteomics research by NMR. Performance of this experiment has been demonstrated using (13)C/(15)N labeled ubiquitin.

  19. Seasonal variation in nitrogen pools and 15N/13C natural abundances in different tissues of grassland plants

    Directory of Open Access Journals (Sweden)

    J. K. Schjoerring

    2011-12-01

    Full Text Available Seasonal changes in nitrogen (N pools, carbon (C content and natural abundance of 13C and 15N in different tissues of ryegrass plants were investigated in two intensively managed grassland fields in order to address their ammonia (NH3 exchange potential. Green leaves generally had the largest total N concentration followed by stems and inflorescences. Senescent leaves had the lowest N concentration, indicating N re-allocation. The seasonal pattern of the Γ value, i.e. the ratio between NH4+ and H+ concentrations, was similar for the various tissues of the ryegrass plants but the magnitude of Γ differed considerably among the different tissues. Green leaves and stems generally had substantially lower Γ values than senescent leaves and litter. Substantial peaks in Γ were observed during spring and summer in response to fertilization and grazing. These peaks were associated with high NH4+ rather than with low H+ concentrations. Peaks in Γ also appeared during the winter, coinciding with increasing δ15N values, indicating absorption of N derived from mineralization of soil organic matter. At the same time, δ13C values were declining, suggesting reduced photosynthesis and capacity for N assimilation. δ15N and δ13C values were more influenced by mean monthly temperature than by the accumulated monthly precipitation. In conclusion, ryegrass plants showed a clear seasonal pattern in N pools. Green leaves and stems of ryegrass plants generally seem to constitute a sink for NH3, while senescent leaves have a large potential for NH3 emission. However, management events such as fertilisation and grazing may create a high NH3 emission potential even in green plant parts. The obtained results provide input for future modelling of plant-atmosphere NH3 exchange.

  20. Redox-controlled backbone dynamics of human cytochrome c revealed by {sup 15}N NMR relaxation measurements

    Energy Technology Data Exchange (ETDEWEB)

    Sakamoto, Koichi [Division of Chemistry, Graduate School of Science, Hokkaido University, Sapporo 060-0810 (Japan); Kamiya, Masakatsu [Graduate School of Life Science, Hokkaido University, Sapporo 060-0810 (Japan); Faculty of Advanced Life Science, Hokkaido University, Sapporo 060-0810 (Japan); Uchida, Takeshi [Division of Chemistry, Graduate School of Science, Hokkaido University, Sapporo 060-0810 (Japan); Department of Chemistry, Faculty of Science, Hokkaido University, Sapporo 060-0810 (Japan); Kawano, Keiichi [Graduate School of Life Science, Hokkaido University, Sapporo 060-0810 (Japan); Faculty of Advanced Life Science, Hokkaido University, Sapporo 060-0810 (Japan); Ishimori, Koichiro, E-mail: koichiro@sci.hokudai.ac.jp [Division of Chemistry, Graduate School of Science, Hokkaido University, Sapporo 060-0810 (Japan); Department of Chemistry, Faculty of Science, Hokkaido University, Sapporo 060-0810 (Japan)

    2010-07-23

    Research highlights: {yields} The dynamic parameters for the backbone dynamics in Cyt c were determined. {yields} The backbone mobility of Cyt c is highly restricted due to the covalently bound heme. {yields} The backbone mobility of Cyt c is more restricted upon the oxidation of the heme. {yields} The redox-dependent dynamics are shown in the backbone of Cyt c. {yields} The backbone dynamics of Cyt c would regulate the electron transfer from Cyt c. -- Abstract: Redox-controlled backbone dynamics in cytochrome c (Cyt c) were revealed by 2D {sup 15}N NMR relaxation experiments. {sup 15}N T{sub 1} and T{sub 2} values and {sup 1}H-{sup 15}N NOEs of uniformly {sup 15}N-labeled reduced and oxidized Cyt c were measured, and the generalized order parameters (S{sup 2}), the effective correlation time for internal motion ({tau}{sub e}), the {sup 15}N exchange broadening contributions (R{sub ex}) for each residue, and the overall correlation time ({tau}{sub m}) were estimated by model-free dynamics formalism. These dynamic parameters clearly showed that the backbone dynamics of Cyt c are highly restricted due to the covalently bound heme that functions as the stable hydrophobic core. Upon oxidation of the heme iron in Cyt c, the average S{sup 2} value was increased from 0.88 {+-} 0.01 to 0.92 {+-} 0.01, demonstrating that the mobility of the backbone is further restricted in the oxidized form. Such increases in the S{sup 2} values were more prominent in the loop regions, including amino acid residues near the thioether bonds to the heme moiety and positively charged region around Lys87. Both of the regions are supposed to form the interaction site for cytochrome c oxidase (CcO) and the electron pathway from Cyt c to CcO. The redox-dependent mobility of the backbone in the interaction site for the electron transfer to CcO suggests an electron transfer mechanism regulated by the backbone dynamics in the Cyt c-CcO system.

  1. Tracing the diet of the monitor lizard Varanus mabitang by stable isotope analyses (δ15N, δ13C)

    Science.gov (United States)

    Struck, Ulrich; Altenbach, Alexander; Gaulke, Maren; Glaw, Frank

    2002-09-01

    In this study, we used analyses of stable isotopes of nitrogen (δ15N) and carbon (δ13C) to determine the trophic ecology of the monitor lizard Varanus mabitang. Stable isotopes from claws, gut contents, and soft tissues were measured from the type specimen. Samples from Varanus olivaceus, Varanus prasinus, Varanus salvator, the herbivorous agamid lizard Hydrosaurus pustulatus, and some plant matter were included for comparison. Our data show a rapid decrease in δ13C (about10‰) from food plants towards gut contents and soft tissues of herbivorous species. For the varanids, we found a significant linear correlation of decreasing δ13C and increasing δ15N from herbivorous towards carnivorous species. In terms of trophic isotope ecology, the type specimen of V. mabitang is a strict herbivore. Thus it differs significantly in its isotopic composition from the morphologically next closest related species V. olivaceus. The most highly carnivorous species is V. salvator, while δ15N values for V. prasinus and V. olivaceus are intermediate. Claws provide very valuable samples for such measurements, because they can be sampled from living animals without harm. Additionally, their range of variability is relatively small in comparison with measurements from soft tissues.

  2. The δ15N of nitrate in the Southern Ocean: Nitrogen cycling and circulation in the ocean interior

    Science.gov (United States)

    Sigman, D. M.; Altabet, M. A.; McCorkle, D. C.; Francois, R.; Fischer, G.

    2000-08-01

    We report analyses of the nitrogen isotopic composition of nitrate in the eastern Indian and Pacific sectors of the Southern Ocean. In this paper, we focus on the subsurface data as well as data from the deep waters of other ocean basins. Nitrate δ15N is relatively invariant in much of the abyssal ocean (i.e., below 2.5 km), with a value of 4.8±0.2‰ observed in Lower Circumpolar Deep Water, North Atlantic Deep Water, and central Pacific deep water. The isotopic invariance of deep ocean nitrate stems fundamentally from the completeness of nitrate utilization in most of the global surface ocean, the Southern Ocean surface being an important exception. In the Subantarctic Zone (north of the Polar Frontal Zone) the nitrate δ15N of Upper Circumpolar Deep Water is ˜0.7‰ greater than that of Lower Circumpolar Deep Water. This isotopic enrichment appears to result from denitrification in the low-latitude water masses with which Upper Circumpolar Deep Water communicates. The isotopic enrichment of Upper Circumpolar Deep Water is diminished in the Antarctic, probably because of the remineralization of sinking organic N, which has a low δ15N in the Antarctic. Relative to the other water masses of the Southern Ocean, the Subantarctic thermocline has a very low nitrate δ15N for its nitrate concentration because of exchange with the low-latitude thermocline, where this isotopic signature appears to originate. This signature of the low-latitude thermocline has two probable causes: (1) mixing with low-nitrate surface water and (2) the oxidation of newly fixed N.

  3. Use of a 15N tracer to determine linkages between a mangrove and an upland freshwater swamp

    Science.gov (United States)

    MacKenzie, R. A.; Cormier, N.

    2005-05-01

    Mangrove forests and adjacent upland freshwater swamps are important components of subsistence-based economies of Pacific islands. Mangroves provide valuable firewood (Rhizophora apiculata) and mangrove crabs (Scylla serrata); intact freshwater swamps are often used for agroforestry (e.g., taro cultivation). While these two systems are connected hydrologically via groundwater and surface flows, little information is available on how they may be biogeochemically or ecologically linked. For example, mangrove leaf litter was once thought to be an important food source for resident and transient nekton and invertebrates, but this value may have been overestimated. Instead, nutrients or allochthonous material (e.g., phytoplankton, detritus) delivered via groundwater or surface water from upland freshwater swamps may play a larger role in mangrove food webs. Understanding the linkages between these two ecologically and culturally important ecosystems will help us to understand the potential impacts of hydrological alterations that occur when roads or bridges are constructed through them. We conducted a 15N tracer study in the Yela watershed on the island of Kosrae, Federated States of Micronesia. K15NO3 was continually added at trace levels for 4 weeks to the Yela River in an upland freshwater swamp adjacent to a mangrove forest. Nitrate and ammonium pools, major primary producers, macroinvertebrates, and fish were sampled from stations 5 m upstream (freshwater swamp) and 138, 188, 213, and 313 m downstream (mangrove) from the tracer addition. Samples were collected once a week prior to, during, and after the 15N addition for a total of 6 weeks. Preliminary results revealed no significant enrichment (< 1 ‰) in the 15N isotope composition of either resident shrimp (Macrobrachium sp.) or mudskipper fish (Periophthalmus sp.). However, the 15N signature of ammonium pools was enriched 10-60 ‰ by the end of the third week. These results suggest that the tracer was present

  4. Effects of foliar boron application on seed composition, cell wall boron, and seed delta 15N and delta 13C isotopes in soybean are influenced by water stress

    Science.gov (United States)

    Although the effect of foliar boron (B) application on yield and quality is well established for crops, limited information and controversial results still exist on the effects of foliar B application on soybean seed composition (seed protein, oil, fatty acids, and sugars). The objective of this res...

  5. {delta}{sup 13}C and {delta}{sup 15}N shifts in benthic invertebrates exposed to sewage from McMurdo Station, Antarctica

    Energy Technology Data Exchange (ETDEWEB)

    Conlan, Kathleen E. [Canadian Musem of Nature, P.O. Box 3443 Station D, Ottawa, Ont., K1P 6P4 (Canada)]. E-mail kconlan@mus-nature.ca; Rau, Greg H. [Institute of Marine Sciences, University of California, Santa Cruz, CA 95064 (United States); Kvitek, Rikk G. [Earth Systems Science and Policy, California State University Monterey Bay, 100 Campus Center, Seaside, CA 93955 (United States)

    2006-12-15

    In an effort to identify biomonitors for contamination of Antarctic marine benthos by sewage, this study determines whether the US Antarctic Program's McMurdo Station produces a benthic sewage footprint and whether resident megafauna are assimilating sewage-derived material. We identified strong C and N isotopic gradients in benthic sediment as a function of downstream distance from McMurdo Station's point-source sewage addition. Sediment C and N isotope ratios approached marine background levels at the sampling end-point 612 m downcurrent. Based on isotope abundances in their tissues, at least some sewage C and N were assimilated by the sedentary, suspension feeding soft coral Alcyonium antarcticum, ascidian Cnemidocarpa verrucosa and bivalve Laternula elliptica. However, as inferred by tissue-sediment differences in downstream isotope trends, such assimilation was not in proportion to sewage exposure and input, therefore implying non-generalist feeding behavior by these species. In contrast, the motile, generalist feeding sea urchin Sterechinus neumayeri, sea star Odontaster validus and ribbon worm Parborlasia corrugatus showed isotopic evidence of sewage C and N assimilation roughly in proportion to sewage input. We recommend these generalist feeders for further use as biomonitors at this site now that sewage treatment has been implemented. As these species are circumpolar in distribution, they may also prove useful elsewhere in the Antarctic.

  6. Organic Aggregates with (delta)D and delta(sup 15)N Anomalies in the Zag Clast Revealed by STXM and NanoSIMS

    Science.gov (United States)

    Kebukawa, Y.; Ito, M.; Zolensky, M. E.; Rahman, Z.; Kilcoyne, A. L. D.; Nakato, A.; Takeichi, Y.; Suga, H.; Miyamoto, C.; Mase, K.; Takahashi, Y.; Chan, Q.; Fries, M.

    2016-01-01

    Xenolithic clasts are often found in a wide variety of meteorite groups. Some ordinary chondrite clasts are interesting since these clasts might have originated from Ceres which shares crossing orbits with a possible ordinary chondrite parent body, Hebe. The Zag meteorite contains a dark clast dominated by saponite, serpentine, carbonates, sulfides, magnetite, minor olivine and pyroxene, which is consistent with formation on a large, carbonaceous, aqueously active body, e.g., Ceres. Abundant large C-rich grains up to 20 microns were found in the Zag clast as well. Such large C-rich grains are unique among any other meteorites in our knowledge, and will provide important clues to decipher the origin of the clast and accretion history. C-rich grains were selected in the Zag dark clast using SEM and approximately 100 nm-thick sections were prepared using a focused ion beam (FIB) at NASA-JSC. The sections were analyzed using the scanning transmission X-ray microscope (STXM) on beamline 5.3.2.2 at Advanced Light Source, LBNL, and BL-13A at the Photon Factory, KEK. Subsequently, the FIB section was analyzed for H, C and N isotopic compositions using a CAMECA NanoSIMS 50L ion microprobe at Kochi Institute for Core Sample Research, JAMSTEC

  7. Interpreting δ15N in Soil Profiles: Insights From the N-Isotopes of Amino Acids

    Science.gov (United States)

    Philben, M. J.; Edwards, K. A.; Billings, S. A.; Van Biesen, G.; Podrebarac, F. A.; Ziegler, S. E.

    2016-12-01

    The δ15N of soil organic matter is consistently enriched with depth in soil profiles, although the magnitude of enrichment appears to vary with latitude. This could provide important insights on differences in N cycling among ecosystems, but the mechanism responsible for the depth trend remains controversial. Hypothesized explanations are (1) selective loss of depleted N during decomposition; (2) accumulation of 15N-enriched biomass of decomposers at depth; and (3) transfer of depleted N from depth to the soil surface by mycorrhizal fungi. To constrain these possible mechanisms, we analyzed the δ15N of hydrolyzable amino acids in the L, F, and H soil horizons of 2 boreal forests in southeast Labrador and southwest Newfoundland, Canada, before and after 480-day laboratory incubations of the soils. Most amino acids are both produced and degraded by microbes, but some are not resynthesized. The difference between these groups can be used to isolate the effects of decomposition from other fractionating processes. The amino acid δ15N did not change during the soil incubations, indicating peptide depolymerization does not fractionate N isotopes. This is consistent with a previously conducted fallow experiment in which amino acid δ15N remained unchanged after 68 years of decomposition in the absence of plant inputs. In contrast, the δ15N of most amino acids were enriched by 3-7‰ from the L to the H horizon, similar to the enrichment of bulk δ15N with depth. This pattern suggests these amino acids were resynthesized deeper in the soil profile where the bulk δ15N was more enriched. The δ15N amino acids phenylalanine and hydroxyproline, which are not resynthesized by the microbial community with decomposition, did not change with depth, indicating the depth trend was not due to temporal change in the δ15N of plant inputs to the soil. The enrichment of amino acid δ15N with depth in the soil profiles but not in the incubations or the fallow experiment indicates

  8. Delta III—an evolutionary delta growth

    Science.gov (United States)

    Arvesen, R. J.; Simpson, J. S.

    1996-03-01

    In order to remain competitive in the future and expand the McDonnell Douglas Aerospace market share, MDA has developed an expendable launch system strategy that devices cost-effective launch systems from the Delta II with a growth vehicle configuration called Delta III. The Delta III evolves from the Delta II launch system through development of a larger payload fairing (4-meter diameter), new cryogenically propelled upper stage, new first stage fuel tank, and larger strap-on solid rocket motors. We are developing the Delta III using Integrated Product Development Teams that capitalize on the experience base that has led us to a world record breaking mission success of 49 consecutive Delta II missions. The Delta III first-launch capability is currently planned for the spring of 1998 in support of our first spacecraft customer, Hughes Space and Communications International.

  9. delta(13)C and delta(2)H isotope ratios in amphetamine synthesized from benzaldehyde and nitroethane.

    Science.gov (United States)

    Collins, Michael; Salouros, Helen; Cawley, Adam T; Robertson, James; Heagney, Aaron C; Arenas-Queralt, Andrea

    2010-06-15

    Previous work in these laboratories and by Butzenlechner et al. and Culp et al. has demonstrated that the delta(2)H isotope value of industrial benzaldehyde produced by the catalytic oxidation of toluene is profoundly positive, usually in the range +300 per thousand to +500 per thousand. Synthetic routes leading to amphetamine, methylamphetamine or their precursors and commencing with such benzaldehyde may be expected to exhibit unusually positive delta(2)H values. Results are presented for delta(13)C and delta(2)H isotope values of 1-phenyl-2-nitropropene synthesized from an industrial source of benzaldehyde, having a positive delta(2)H isotope value, by a Knoevenagel condensation with nitroethane. Results are also presented for delta(13)C and delta(2)H isotope values for amphetamine prepared from the resulting 1-phenyl-2-nitropropene. The values obtained were compared with delta(13)C and delta(2)H isotope values obtained for an amphetamine sample prepared using a synthetic route that did not involve benzaldehyde. Finally, results are presented for samples of benzaldehyde, 1-phenyl-2-nitropropene and amphetamine that had been seized at a clandestine amphetamine laboratory.

  10. Dynamics of δ(15)N isotopic signatures of different intertidal macroalgal species: Assessment of bioindicators of N sources in coastal areas.

    Science.gov (United States)

    Lemesle, Stéphanie; Erraud, Alexandre; Mussio, Isabelle; Rusig, Anne-Marie; Claquin, Pascal

    2016-09-15

    δ(15)N of annual (Ulva sp., Porphyra sp.) and perennial intertidal seaweed species (Chondrus crispus, Fucus sp.) collected on 17 sampling points along the French coast of the English Channel in 2012 and 2013 were assessed on their suitability as bioindicators of N pollution in coastal areas. A sine function applied for δ(15)N time series data showed for all the species the same seasonal trend with lowest δ(15)N values in April and highest in summer but with no significant interspecific differences of amplitude (α) and phase angle (ϕ). This model provides a useful tool for monitoring the inter-annual changes of N pollution. An interspecific variability of δ(15)N values was observed, probably due to their tolerance to emersion. An in vitro study for comparing the kinetic acquisition of the isotopic signal and N uptake mechanisms of each species underlined the influence of algal physiology on the δ(15)N interspecific variability. Copyright © 2016 Elsevier Ltd. All rights reserved.

  11. Conformational analysis of capsaicin using 13C, 15N MAS NMR, GIAO DFT and GA calculations

    Science.gov (United States)

    Siudem, Paweł; Paradowska, Katarzyna; Bukowicki, Jarosław

    2017-10-01

    Capsaicin produced by plants from genus Capsicum exerts multiple pharmacological effects and has found applications in food and pharmaceutical industry. The alkaloid was studied by a combined approach: solid-state NMR, GA conformational search and GIAO DFT methods. The 13C CPMAS NMR spectra were recorded using variable contact time and dipolar dephasing experiments. The results of cross-polarization (CP) kinetics, such as TCP values and long T1ρH (100-200 ms), indicated that the capsaicin molecule is fairly mobile, especially at the end of the aliphatic chain. The15N MAS NMR spectrum showed one narrow signal at -255 ppm. Genetic algorithm (GA) search with multi modal optimization was used to find low-energy conformations of capsaicin. Theoretical GIAO DFT calculations were performed using different basis sets to characterize five selected conformations. 13C CPMAS NMR was used as a validation method and the experimental chemical shifts were compared with those calculated for selected stable conformers. Conformational analysis suggests that the side chain can be bent or extended. A comparison of the experimental and the calculated chemical shifts indicates that solid capsaicin does not have the same structure as those established by PWXRD.

  12. Eastern oyster (Crassostrea virginica) δ15N as a bioindicator of nitrogen sources: Observations and modeling

    Science.gov (United States)

    Fertig, B.; Carruthers, T.J.B.; Dennison, W.C.; Fertig, E.J.; Altabet, M.A.

    2013-01-01

    Stable nitrogen isotopes (δ15N) in bioindicators are increasingly employed to identify nitrogen sources in many ecosystems and biological characteristics of the eastern oyster (Crassostrea virginica) make it an appropriate species for this purpose. To assess nitrogen isotopic fractionation associated with assimilation and baseline variations in oyster mantle, gill, and muscle tissue δ15N, manipulative fieldwork in Chesapeake Bay and corresponding modeling exercises were conducted. This study (1) determined that five individuals represented an optimal sample size; (2) verified that δ15N in oysters from two locations converged after shared deployment to a new location reflecting a change in nitrogen sources; (3) identified required exposure time and temporal integration (four months for muscle, two to three months for gill and mantle); and (4) demonstrated seasonal δ15N increases in seston (summer) and oysters (winter). As bioindicators, oysters can be deployed for spatial interpolation of nitrogen sources, even in areas lacking extant populations. PMID:20381097

  13. 15N NMR Spectroscopic Study on Nitrogen Formsin1mmHumic Substances of Soils

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    Nitrogen forms of humic substances from a subalpine meadow soil, alateritic red soil and a weathered coal and the effect of acidhydrolysis on N structures of soil humic substances were studied byusing {15N cross-polarization magic angle spinning nuclearmagnetic resonance (CPMAS NMR) spectroscopy. Of the detectable15N-signal intensity in the spectra of soil humic substances71%79% may be attributed to amide groups, 10%18%to aromatic/aliphatic amines and 6%11% to indole- andpyrrole-like N. Whereas in the spectrum of the fulvic acid fromweathered coal 46%, at least, of the total 15N-signalintensity might be assigned to pyrrole-like N, 14% toaromatic/aliphatic amines, and the remaining intensities could not beassigned with certainty. Data on nonhydrolyzable residue ofprotein-sugar mixture and a 15N-labelled soil fulvic acidconfirm the formation of nonhydrolyzable heterocyclic N during acidhydrolysis.

  14. CO2 concentrations and delta13C (CO2) values in monthly sets of air samples from downtown Parma and the Parma and Taro river valleys, Emilia-Romagna, Italy.

    Science.gov (United States)

    Longinelli, Antonio; Selmo, Enricomaria

    2006-09-01

    Monthly sets of discrete air samples were collected from September 2004 to June 2005 in the town of Parma, along North-South and East-West runs (8 plus 8 samples), using four-litre Pyrex flasks. The CO2 concentrations and delta13C values were determined on these samples with the aim of evaluating quantitatively the contribution of domestic heating to the winter atmospheric CO2 pollution in downtown Parma by comparing autumn and spring atmospheric values with winter values. After separation of CO2 from the other air gases in the laboratory, the CO2 concentrations were calculated from the intensity of the 12C16O2+ ion beam in the mass spectrometer, after calibration with artificial air samples whose CO2 concentration was very carefully determined by the Monte Cimone Observatory (Sestola, Modena, Italy). The reproducibility of these measurements was of approximately +/-0.4 % and, consequently, the most probable error is not higher than+/-2-3 ppmv and does not affect the magnitude of the gradients between different samples. The standard deviation of delta13C measurements ranges from+/-0.02 to +/-0.04 per thousand (1sigma). The results suggest that the contribution of domestic heating to atmospheric CO2 pollution is almost negligible in the case of ground level atmosphere, where the main CO2 pollution is essentially related to the heavy car traffic. This is probably because of the fact that the gases from the domestic heating systems are discharged tens of metres above ground level at a relatively high temperature so that they rise quickly to the upper atmospheric layers and are then displaced by air masses dynamics. Monthly sets of discrete air samples were also collected from October 2004 to June 2005 along North-South runs from the town of Parma to the Apennine ridge following the Parma and the Taro river valleys (8 samples and 7 samples per set, respectively) and measured using the same technique. The aim of this study was the comparison between the town samples

  15. Compaction stimulates denitrification in an urban park soil using 15N tracing technique

    DEFF Research Database (Denmark)

    Li, Shun; Deng, Huan; Rensing, Christopher Günther T

    2014-01-01

    Soils in urban areas are subjected to compaction with accelerating urbanization. The effects of anthropogenic compaction on urban soil denitrification are largely unknown. We conducted a study on an urban park soil to investigate how compaction impacts denitrification. By using 15N labeling method......, no statistical difference in total N losses and 15N-(N2O+N2) flux between the uncompacted soil and the compacted soil was detected. Compaction promoted soil denitrification and may impact urban N biogeochemical cycling....

  16. Determination of gamma-ray widths in $^{15}$N using nuclear resonance fluorescence

    OpenAIRE

    Szücs, T.; Bemmerer, D.; Caciolli, A.; Fülöp, Zs.; Massarczyk, R.; Michelagnoli, C.; Reinhardt, T. P.; Schwengner, R.; Takács, M. P.; Ur, C. A.; Wagner, A.; Wagner, L.

    2015-01-01

    The stable nucleus $^{15}$N is the mirror of $^{15}$O, the bottleneck in the hydrogen burning CNO cycle. Most of the $^{15}$N level widths below the proton emission threshold are known from just one nuclear resonance fluorescence (NRF) measurement, with limited precision in some cases. A recent experiment with the AGATA demonstrator array determined level lifetimes using the Doppler Shift Attenuation Method (DSAM) in $^{15}$O. As a reference and for testing the method, level lifetimes in $^{1...

  17. The First in Vivo Observation of 13C- 15N Coupling in Mammalian Brain

    Science.gov (United States)

    Kanamori, Keiko; Ross, Brian D.

    2001-12-01

    [5-13C,15N]Glutamine, with 1J(13C-15N) of 16 Hz, was observed in vivo in the brain of spontaneously breathing rats by 13C MRS at 4.7 T. The brain [5-13C]glutamine peak consisted of the doublet from [5-13C,15N]glutamine and the center [5-13C,14N]glutamine peak, resulting in an apparent triplet with a separation of 8 Hz. The time course of formation of brain [5-13C,15N]glutamine was monitored in vivo with a time resolution of 20-35 min. This [5-13C,15N]glutamine was formed by glial uptake of released neurotransmitter [5-13C]glutamate and its reaction with 15NH3 catalyzed by the glia-specific glutamine synthetase. The neurotransmitter glutamate C5 was selectively13C-enriched by intravenous [2,5-13C]glucose infusion to 13C-label whole-brain glutamate C5, followed by [12C]glucose infusion to chase 13C from the small and rapidly turning-over glial glutamate pool, leaving 13C mainly in the neurotransmitter [5-13C]glutamate pool, which is sequestered in vesicles until release. Hence, the observed [5-13C,15N]glutamine arises from a coupling between 13C of neuronal origin and 15N of glial origin. Measurement of the rate of brain [5-13C,15N]glutamine formation provides a novel noninvasive method of studying the kinetics of neurotransmitter uptake into glia in vivo, a process that is crucial for protecting the brain from glutamate excitotoxicity.

  18. The Delta 2 launcher

    Science.gov (United States)

    Ousley, Gilbert W., Sr.

    1991-12-01

    The utilization of the Delta 2 as the vehicle for launching Aristoteles into its near Sun synchronous orbit is addressed. Delta is NASA's most reliable launch vehicle and is well suited for placing the present Aristoteles spacecraft into a 400 m circular orbit. A summary of some of the Delta 2 flight parameters is presented. Diagrams of a typical Delta 2 two stage separation are included along with statistics on delta reliability and launch plans.

  19. Direct contribution of nitrogen deposition to nitrous oxide emissions in a temperate beech and spruce forest – a 15N tracer study

    Directory of Open Access Journals (Sweden)

    E. Veldkamp

    2011-03-01

    Full Text Available The impact of atmospheric nitrogen (N deposition on nitrous oxide (N2O emissions in forest ecosystems is still unclear. Our study assessed the direct contribution of N deposition to N2O emissions in temperate forests exposed to chronic high N depositions using a 15N labelling technique. In a Norway spruce stand (Picea abies and in a beech stand (Fagus sylvatica at the Solling, Germany, we used a low concentrated 15N-labelled ammonium-nitrate solution to simulate N deposition. Nitrous oxide fluxes and 15N isotope abundances in N2O were measured using the closed chamber method combined with 15N isotope analyses. Emissions of N2O were higher in the beech stand (2.6 ± 0.6 kg N ha−1 yr−1 than in the spruce stand (0.3 ± 0.1 kg N ha−1 yr−1. We observed a direct effect of N input on 15N-N2O emissions, which lasted for less than three weeks and was mainly caused by denitrification. No further increase in 15N enrichment of N2O occurred during a one-year experiment, which was probably due to immobilisation of deposited N. The annual emission factor for N2O from deposited N was 0.1% for the spruce stand and 0.6% for the beech stand. Standard methods used in the literature applied to the same stands grossly overestimated emission factors with values of up to 25%. Only 6–13% of the total N2O emissions were derived from direct N depositions. Whether the remaining emissions resulted from accumulated anthropogenic N depositions or native soil N, could not be distinguished with the applied methods. The 15N tracer technique is a useful tool, which may improve estimates of the current contribution of N deposition to N2O emissions.

  20. FIRST MEASUREMENTS OF {sup 15}N FRACTIONATION IN N{sub 2}H{sup +} TOWARD HIGH-MASS STAR-FORMING CORES

    Energy Technology Data Exchange (ETDEWEB)

    Fontani, F. [INAF-Osservatorio Astrofisico di Arcetri, L.go E. Fermi 5, I-50125 Firenze (Italy); Caselli, P.; Bizzocchi, L. [Max Planck Institute for Extraterrestrial Physics, Giessenbachstrasse 1, D-85748 Garching (Germany); Palau, A. [Centro de Radioastronomía y Astrofísica, Universidad Nacional Autónoma de México, P.O. Box 3-72, 58090 Morelia, Michoacán, México (Mexico); Ceccarelli, C. [Univ. Grenoble Alpes, IPAG, F-38000 Grenoble (France)

    2015-08-01

    We report on the first measurements of the isotopic ratio {sup 14}N/{sup 15}N in N{sub 2}H{sup +} toward a statistically significant sample of high-mass star-forming cores. The sources belong to the three main evolutionary categories of the high-mass star formation process: high-mass starless cores, high-mass protostellar objects, and ultracompact H ii regions. Simultaneous measurements of the {sup 14}N/{sup 15}N ratio in CN have been made. The {sup 14}N/{sup 15}N ratios derived from N{sub 2}H{sup +} show a large spread (from ∼180 up to ∼1300), while those derived from CN are in between the value measured in the terrestrial atmosphere (∼270) and that of the proto-solar nebula (∼440) for the large majority of the sources within the errors. However, this different spread might be due to the fact that the sources detected in the N{sub 2}H{sup +} isotopologues are more than those detected in the CN ones. The {sup 14}N/{sup 15}N ratio does not change significantly with the source evolutionary stage, which indicates that time seems to be irrelevant for the fractionation of nitrogen. We also find a possible anticorrelation between the {sup 14}N/{sup 15}N (as derived from N{sub 2}H{sup +}) and the H/D isotopic ratios. This suggests that {sup 15}N enrichment could not be linked to the parameters that cause D enrichment, in agreement with the prediction by recent chemical models. These models, however, are not able to reproduce the observed large spread in {sup 14}N/{sup 15}N, pointing out that some important routes of nitrogen fractionation could be still missing in the models.

  1. Determination of gamma-ray widths in $^{15}$N using nuclear resonance fluorescence

    CERN Document Server

    Szücs, T; Caciolli, A; Fülöp, Zs; Massarczyk, R; Michelagnoli, C; Reinhardt, T P; Schwengner, R; Takács, M P; Ur, C A; Wagner, A; Wagner, L

    2015-01-01

    The stable nucleus $^{15}$N is the mirror of $^{15}$O, the bottleneck in the hydrogen burning CNO cycle. Most of the $^{15}$N level widths below the proton emission threshold are known from just one nuclear resonance fluorescence (NRF) measurement, with limited precision in some cases. A recent experiment with the AGATA demonstrator array determined level lifetimes using the Doppler Shift Attenuation Method (DSAM) in $^{15}$O. As a reference and for testing the method, level lifetimes in $^{15}$N have also been determined in the same experiment. The latest compilation of $^{15}$N level properties dates back to 1991. The limited precision in some cases in the compilation calls for a new measurement in order to enable a comparison to the AGATA demonstrator data. The widths of several $^{15}$N levels have been studied with the NRF method. The solid nitrogen compounds enriched in $^{15}$N have been irradiated with bremsstrahlung. The $\\gamma$-rays following the deexcitation of the excited nuclear levels were dete...

  2. Production of 15N-Labelled Liquid Organic Fertilisers Based on Manure and Crop Residue for Use in Fertigation Studies.

    Directory of Open Access Journals (Sweden)

    Belén Martínez-Alcántara

    Full Text Available Large quantities of crop residue and animal manure from agricultural and livestock activities are annually produced worldwide. With proper management, these residues are potentially valuable sources of plant nutrients, mainly N. Recycling such subproducts in sustainably-based agricultural systems can minimise the use of mineral fertilisers, and hence reduce the potential risk of surface and groundwater pollution. Therefore, the purpose of this study was to obtain (small scale two liquid labelled-organic fertilisers, an animal- and a vegetal-based organic (AO and VO, respectively fertiliser, to be used as organic N sources in subsequent fertigation studies. Forage maize (Zea mays L. grown under 15N-labelled fertiliser supply was used as raw material for VO fertiliser production, and also as 15N-labelled sheep feed to obtain 15N-labelled manure. The labelled faeces fraction was used as raw material for the AO fertiliser. The VO fertiliser was obtained after an acidic and an enzyme-driven hydrolysis. The AO fertiliser was obtained after acidic hydrolysis. The VO liquid fertiliser presented an N concentration of 330 mg·L-1, 85% of total N was organic, while ammonium and nitrate N accounted for 55% and 45% of the mineral nitrogen fraction, respectively. This fertiliser also exhibited high K, Ca and S concentrations and notable values for the remaining macro- and micronutrients. The AO liquid fertiliser had a similar total N concentration (496 mg·L-1, 82% of total N in an organic form to that of VO, but its mineral N fraction significantly differed, which came in a predominantly (95% ammonia form. It also had a high content of N, P, K and other macronutrients, and sufficient Fe, Zn, Mn, Cu and B levels, which suggests its suitability as a potential fertiliser. The percentage of 15N enrichment in both VO and AO liquid fertilisers exceeded 2% 15N atom excess, which enabled their use in subsequent assays run to assess nitrogen uptake efficiency.

  3. Searching for long-term trends in prehistoric manuring practice. δ15N analyses of charred cereal grains from the 4th to the 1st millennium BC

    DEFF Research Database (Denmark)

    Kanstrup, Marie; Holst, M.K.; Jensen, Peter Mose

    2014-01-01

    investigation of long term trends in δ15N values of charred cereal grains, which previous research have proposed as an indicator for prehistoric manuring practice. Our study suggests a long-term (3900–500 BC) decrease of manuring intensity in emmer cropping. Conversely the long-term (2300 BC – AD 1) trend...

  4. True cooking aroma or artefact. {sup 15}N gives the answer; Veritable arome de cuisson ou artefact. {sup 15}N fournit la reponse

    Energy Technology Data Exchange (ETDEWEB)

    Metro, F.; Boudaud, N.; Dumont, J.P. [INRA, 44 - Nantes (France)

    1994-12-31

    In order to determine the respective contributions of the various nitrous precursor families in aroma preparations, the usually added amino acids were substituted with {sup 15}N isotope labelled homologous components. Results concerning isotope ratios for the volatile fraction nitrous components collected from poultry meat aromatic preparations, are presented. Terminal product labelling appears to allow for a better determination of the substrate and functional additive contributions. 4 figs., 6 refs.

  5. Absorption of ammonium sulphate {sup 15}N by coffee plants; Recuperacao do {sup 15}N do sulfato de amonio por plantas de cafe

    Energy Technology Data Exchange (ETDEWEB)

    Fenilli, Tatiele Anete Bergamo; Reichardt, Klaus; Bacchi, Osny Oliveira Santos [Centro de Energia Nuclear na Agricultura (CENA), Piracicaba, SP (Brazil). Lab. de Fisica do Solo]. E-mail: tatiele@cena.usp.br; Trivelin, Paulo Cesar Ocheuze [Centro de Energia Nuclear na Agricultura (CENA), Piracicaba, SP (Brazil). Lab. de Isotopos Estaveis; Dourado Neto, Durval [Sao Paulo Univ., Piracicaba, SP (Brazil). Escola Superior de Agricultura Luiz de Queiroz. Dept. de Producao Vegetal

    2005-07-01

    The objective of this study was to quantify the absorption of ammonium sulphate {sup 15}N by coffee plants. Treatments consisted of five sub-plots of 9 plants, of which the three central ones received 280 kg ha{sup -1} of {sup 15}N, applied at four times: 1/4 on 01 Set 03; 1/4 on 03 Nov 03; 1/4 on 15 Dec 03 and 1/4 on 30 Jan 04. The isotopic enrichment was 2,072 {+-} 0,001 atom % {sup 15}N. The dry matter of the shoot was evaluated every 60 days, using one plant per replicate, collected outside the sub-plot. They were as similar as possible to the labeled plants, which were used only for isotopic and Total N analysis, after being dried at 65 deg C until constant weight. At harvest, plants had absorbed 42,88% of the fertilizer N. Leaves accumulated the largest amount of fertilizer N, and were also the compartments that received most N from other parts of the plant. The following partition of the fertilizer N was found at harvest: 23.01% in young leaves, 6.23% in old leaves, 4,46% in stem, 3.46% in fruits, 3.10% in young branches and 2.63% in old branches. (author)

  6. δ13C and δ15N changes after dietary shift in veliger larvae of the slipper limpet Crepidula fornicata: an experimental evidence

    Science.gov (United States)

    Comtet, T.; Riera, P.

    2006-12-01

    δ13C and δ15N measurements are still poorly conducted in benthic invertebrate larvae. To assess the δ13C and δ15N changes occurring after a dietary shift, experiments were conducted on veliger larvae of Crepidula fornicata fed with two cultured microalgae ( Isochrysis galbana and Pavlova lutheri) of known isotopic composition, 13C-enriched and 15N-depleted compared to the initial values of the larvae. Rapid changes in larval δ13C and δ15N were observed after the dietary shift, with an increase in δ13C and a decrease in δ15N. After 19 days of feeding, isotopic equilibrium was still not reached, a period which is close to the duration of the pelagic life of the larvae. This implies that the isotopic composition measured in field-collected larvae might only partly reflect actual larval feeding but also the parental isotopic signature, especially during the early developmental stages. Isotopic measurements in marine invertebrate larvae should thus be interpreted cautiously. In planktonic food web investigations, the study of field-collected larvae of different size/developmental stage may reduce potential misinterpretations.

  7. The influence of fish cage culture on δ{sup 13}C and δ{sup 15}N of filter-feeding Bivalvia (Mollusca)

    Energy Technology Data Exchange (ETDEWEB)

    Benedito, E.; Takeda, A.M., E-mail: eva@nupelia.uem.br [Universidade Estadual de Maringa (UEM), PR (Brazil). Nucleo de Pesquisas em Limnologia, Ictiologia e Aquicultura; Figueroa, L. [Universidade Estadual de Maringa (UEM), PR (Brazil). Pos-Graduacao em Ecologia de Ambientes Aquaticos Continentais; Manetta, GI. [Universidade Estadual de Maringa (UEM), PR (Brazil). Pos-Graduacao em Biologia Comparada

    2013-11-15

    The objective of this study was to evaluate the effect of Oreochromis niloticus cage culture promoted variations in the δ{sup 13}C and δ{sup 15}N in Corbicula fluminea (Mollusca; Bivalvia) and in the sediment of an aquatic food web. Samples were taken before and after net cage installation in the Rosana Reservoir (Paranapanema River, PR-SP). Samples of specimens of the bivalve filter C. fluminea and samples of sediment were collected using a modified Petersen grab. All samples were dried in an oven (60 °C) for 72 hours, macerated to obtain homogenous fine powders and sent for carbon (δ{sup 13}C) and nitrogen (δ{sup 15}N) isotopic value analysis in a mass spectrometer. There were significant differences in the δ{sup 13}C and δ{sup 15}N values of the invertebrate C. fluminea between the beginning and the end of the experiment. There were no differences between the δ{sup 13}C and δ{sup 15}N values of sediment. These results indicate that the installation of fish cage culture promoted impacts in the isotopic composition of the aquatic food web organisms, which could exert influence over the native species and the ecosystem. (author)

  8. Fossil Fuel Combustion-Related Emissions Dominate Atmospheric Ammonia Sources during Severe Haze Episodes: Evidence from (15)N-Stable Isotope in Size-Resolved Aerosol Ammonium.

    Science.gov (United States)

    Pan, Yuepeng; Tian, Shili; Liu, Dongwei; Fang, Yunting; Zhu, Xiaying; Zhang, Qiang; Zheng, Bo; Michalski, Greg; Wang, Yuesi

    2016-08-02

    The reduction of ammonia (NH3) emissions is urgently needed due to its role in aerosol nucleation and growth causing haze formation during its conversion into ammonium (NH4(+)). However, the relative contributions of individual NH3 sources are unclear, and debate remains over whether agricultural emissions dominate atmospheric NH3 in urban areas. Based on the chemical and isotopic measurements of size-resolved aerosols in urban Beijing, China, we find that the natural abundance of (15)N (expressed using δ(15)N values) of NH4(+) in fine particles varies with the development of haze episodes, ranging from -37.1‰ to -21.7‰ during clean/dusty days (relative humidity: ∼ 40%), to -13.1‰ to +5.8‰ during hazy days (relative humidity: 70-90%). After accounting for the isotope exchange between NH3 gas and aerosol NH4(+), the δ(15)N value of the initial NH3 during hazy days is found to be -14.5‰ to -1.6‰, which indicates fossil fuel-based emissions. These emissions contribute 90% of the total NH3 during hazy days in urban Beijing. This work demonstrates the analysis of δ(15)N values of aerosol NH4(+) to be a promising new tool for partitioning atmospheric NH3 sources, providing policy makers with insights into NH3 emissions and secondary aerosols for regulation in urban environments.

  9. Probing platinum azido complexes by 14N and 15N NMR spectroscopy.

    Science.gov (United States)

    Farrer, Nicola J; Gierth, Peter; Sadler, Peter J

    2011-10-17

    Metal azido complexes are of general interest due to their high energetic properties, and platinum azido complexes in particular because of their potential as photoactivatable anticancer prodrugs. However, azido ligands are difficult to probe by NMR spectroscopy due to the quadrupolar nature of (14)N and the lack of scalar (1)H coupling to enhance the sensitivity of the less abundant (15)N by using polarisation transfer. In this work, we report (14)N and (15)N NMR spectroscopic studies of cis,trans,cis-[Pt(N(3))(2)(OH)(2)(NH(3))] (1) and trans,trans,trans-[Pt(N(3))(2)(OH)(2)(X)(Y)], where X=Y=NH(3) (2); X=NH(3), Y=py (3) (py=pyridine); X=Y=py (4); and selected Pt(II) precursors. These studies provide the first (15)N NMR data for azido groups in coordination complexes. We discuss one- and three-bond J((15)N,(195)Pt) couplings for azido and am(m)ine ligands. The (14)N(α) (coordinated azido nitrogen) signal in the Pt(IV) azido complexes is extremely broad (W(1/2)≈2124 Hz for 4) in comparison to other metal azido complexes, attributable to a highly asymmetrical electric field gradient at the (14)N(α) atom. Through the use of anti-ringing pulse sequences, the (14)N NMR spectra, which show resolution of the broad (14)N(α) peak, were obtained rapidly (e.g., 1.5 h for 10 mM 4). The linewidths of the (14)N(α) signals correlate with the viscosity of the solvent. For (15) N-enriched samples, it is possible to detect azido (15)N resonances directly, which will allow photoreactions to be followed by 1D (15)N NMR spectroscopy. The T(1) relaxation times for 3 and 4 were in the range 5.7-120 s for (15)N, and 0.9-11.3 ms for (14)N. Analysis of the (1)J((15)N,(195)Pt) coupling constants suggests that an azido ligand has a moderately strong trans influence in octahedral Pt(IV) complexes, within the series 2-picIV)-NH(3) bond to a greater extent than an axial OH(-) ligand. Copyright © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  10. Rivermouth alteration of agricultural impacts on consumer tissue δ(15N.

    Directory of Open Access Journals (Sweden)

    James H Larson

    Full Text Available Terrestrial agricultural activities strongly influence riverine nitrogen (N dynamics, which is reflected in the δ(15N of riverine consumer tissues. However, processes within aquatic ecosystems also influence consumer tissue δ(15N. As aquatic processes become more important terrestrial inputs may become a weaker predictor of consumer tissue δ(15N. In a previous study, this terrestrial-consumer tissue δ(15N connection was very strong at river sites, but was disrupted by processes occurring in rivermouths (the 'rivermouth effect'. This suggested that watershed indicators of N loading might be accurate in riverine settings, but could be inaccurate when considering N loading to the nearshore of large lakes and oceans. In this study, the rivermouth effect was examined on twenty-five sites spread across the Laurentian Great Lakes. Relationships between agriculture and consumer tissue δ(15N occurred in both upstream rivers and at the outlets where rivermouths connect to the nearshore zone, but agriculture explained less variation and had a weaker effect at the outlet. These results suggest that rivermouths may sometimes be significant sources or sinks of N, which would cause N loading estimates to the nearshore zone that are typically made at discharge gages further upstream to be inaccurate. Identifying definitively the controls over the rivermouth effect on N loading (and other nutrients will require integration of biogeochemical and hydrologic models.

  11. The agricultural history of human-nitrogen interactions as recorded in ice core δ15N-NO3-

    Science.gov (United States)

    Felix, J. David; Elliott, Emily M.

    2013-04-01

    The advent and industrialization of the Haber Bosch process in the early twentieth century ushered in a new era of reactive nitrogen distributions on Earth. Since the appearance of the first commercial scale Haber Bosch fertilizer plants, fertilizer application rates have greatly increased in the U.S. While the contributions of fertilizer runoff to eutrophication and anoxic dead zones in coastal regions have been well-documented, the potential influences of increased fertilizer applications on air quality and precipitation chemistry are poorly constrained. Here we combine a 255-year record of precipitation nitrate isotopes preserved in a Greenland ice core, historical reconstructions of fertilizer application rates, and field characterization of the isotopic composition of nitrogen oxides produced biogenically in soils, to provide new constraints on the contributions of biogenic emissions to North American NOx inventories. Our results indicate that increases in twentieth century commercial fertilizer use led to large increases in soil NO, a byproduct released during nitrification and denitrification reactions. These large shifts in soil NO production are evidenced by sharp declines in ice core δ15N-NO3- values. Further, these results suggest that biogenic NOx emissions are underestimated by two to four fold in the U.S. NOx emission inventories used to construct global reactive nitrogen budgets. These results demonstrate that nitrate isotopes in ice cores, coupled with newly constrained δ15N-NOx values for NOx emission sources, provide a novel means for estimating contemporary and historic contributions from individual NOx emission sources to deposition.

  12. Delta Plaza kohvik = Delta Plaza cafe

    Index Scriptorium Estoniae

    2010-01-01

    Tallinnas Pärnu mnt 141 asuva kohviku Delta Plaza sisekujundusest. Sisearhitektid Tiiu Truus ja Marja Viltrop (Stuudio Truus OÜ). Tiiu Truusi tähtsamate tööde loetelu. Büroohoone Delta Plaza arhitektid Marika Lõoke ja Jüri Okas (AB J. Okas & M. Lõoke)

  13. Delta Plaza kohvik = Delta Plaza cafe

    Index Scriptorium Estoniae

    2010-01-01

    Tallinnas Pärnu mnt 141 asuva kohviku Delta Plaza sisekujundusest. Sisearhitektid Tiiu Truus ja Marja Viltrop (Stuudio Truus OÜ). Tiiu Truusi tähtsamate tööde loetelu. Büroohoone Delta Plaza arhitektid Marika Lõoke ja Jüri Okas (AB J. Okas & M. Lõoke)

  14. Nitrate retention and removal in Mediterranean streams with contrasting land uses: a 15N tracer study

    Directory of Open Access Journals (Sweden)

    J. L. Riera

    2008-08-01

    Full Text Available We used 15N-labelled nitrate (NO−3 additions to investigate nitrogen (N cycling at the whole-reach scale in three Mediterranean streams subjected to contrasting land uses (i.e. forested, urban and agricultural. Our aim was to examine: i the magnitude and relative importance of NO−3 retention (i.e. assimilatory uptake, and removal, (i.e. denitrification, ii the relative contribution of the different primary uptake compartments to NO−3 retention, and iii the regeneration, transformation and export pathways of the retained N. The concentration of NO−3 increased and that of dissolved oxygen (DO decreased from the forested to the agricultural stream, with intermediate values in the urban stream. Standing stocks of primary uptake compartments were similar among streams and dominated by detritus compartments (i.e. fine and coarse benthic organic matter. In agreement, metabolism was net heterotrophic in all streams, although the degree of heterotrophy increased from the forested to the agricultural stream. The NO−3 uptake length decreased along this gradient, whereas the NO−3 mass-transfer velocity and the areal NO−3 uptake rate were highest in the urban stream. Denitrification was not detectable in the forested stream, but accounted for 9% and 68% of total NO−3 uptake in the urban and the agricultural stream, respectively. The relative contribution of detritus compartments to NO−3 assimilatory uptake was highest in the forested and lowest in the agricultural stream. In all streams, the retained N was rapidly transferred to higher trophic levels and regenerated back to the water column. Due to a strong coupling between regeneration and nitrification, most retained N was exported from the experimental reaches in the form of NO−3. This study evidences fast N cycling in Mediterranean streams. Moreover, results indicate that permanent NO−3 removal via denitrification may be enhanced over temporary NO−3 retention via assimilatory

  15. Synthesis and NMR of {sup 15}N-labeled DNA fragments

    Energy Technology Data Exchange (ETDEWEB)

    Jones, R.A. [Rutgers, The State Univ. of New Jersey, Piscataway, NJ (United States)

    1994-12-01

    DNA fragments labeled with {sup 15}N at the ring nitrogens and at the exocyclic amino groups can be used to obtain novel insight into interactions such as base pairing, hydration, drug binding, and protein binding. A number of synthetic routes to {sup 15}N-labeled pyrimidine nucleosides, purines, and purine nucleosides have been reported. Moreover, many of these labeled bases or monomers have been incorporated into nucleic acids, either by chemical synthesis or by biosynthetic procedures. The focus of this chapter will be on the preparation of {sup 15}N-labeled purine 2{prime}-deoxynucleosides, their incorporation into DNA fragments by chemical synthesis, and the results of NMR studies using these labeled DNA fragments.

  16. Natural 15N abundance of soil N pools and N2O reflect the nitrogen dynamics of forest soils

    DEFF Research Database (Denmark)

    Pörtl, K.; Zechmeister-Boltenstern, S.; Wanek, W.

    2007-01-01

    Natural N-15 abundance measurements of ecosystem nitrogen (N) pools and N-15 pool dilution assays of gross N transformation rates were applied to investigate the potential of delta N-15 signatures of soil N pools to reflect the dynamics in the forest soil N cycle. Intact soil cores were collected...... from pure spruce (Picea abies (L.) Karst.) and mixed spruce-beech (Fagus sylvatica L.) stands on stagnic gleysol in Austria. Soil delta N-15 values of both forest sites increased with depth to 50 cm, but then decreased below this zone. delta N-15 values of microbial biomass (mixed stand: 4.7 +/- 0...... represented the main N2O-producing process in the mixed forest stand as we detected a significant N-15 enrichment of its substrate NO3- (3.6 +/- 4.5 parts per thousand) compared to NH4+ (-4.6 +/- 2.6 parts per thousand) and its product N2O (-11.8 +/- 3.2 parts per thousand). In a N-15-labelling experiment...

  17. Total N difference method and 15N isotope dilution methode - A comparative study on N-fixation

    OpenAIRE

    2002-01-01

    In the study, the 15N fixation of a number of green manure crops were studied using either the 15N dilution technique, or the simple total N difference method. The results of the two methods were not very different, and the total N difference method seemed to give as good results as the more complicated and expencive 15N dillution method.

  18. Mother-embryo isotope (δ15N, δ13C) fractionation and mercury (Hg) transfer in aplacental deep-water sharks

    OpenAIRE

    Le Bourg, Baptiste; Kiszka, Jeremy; Bustamante, Paco

    2014-01-01

    International audience; Stable carbon (δ13C) and nitrogen (δ15N) isotopic values and total mercury (Hg) concentrations were analysed in muscle and liver of mothers and embryos of two aplacental shark species, Squalus megalops and Centrophorus moluccensis. Embryos of the two species had similar or lower isotopic values than their respective mothers, the only exception being for δ13C, which was higher in the liver of C. moluccensis embryos than in their mothers. Hg concentrations were systemati...

  19. Mother-embryo isotope (δ 15 N, δ 13 C) fractionation and mercury (Hg) transfer in aplacental deep-sea sharks : aplacental shark isotope fractionation and hg

    OpenAIRE

    Le Bourg, B.; Kiszka, J.; Bustamante, P.

    2014-01-01

    Stable carbon (δ13C) and nitrogen (δ15N) isotopic values and total mercury (Hg) concentrations were analysed in muscle and liver of mothers and embryos of two aplacental shark species, Squalus megalops and Centrophorus moluccensis. Embryos of the two species had similar or lower isotopic values than their respective mothers, the only exception being for δ13C, which was higher in the liver of C. moluccensis embryos than in their mothers. Hg concentrations were systematically lower in embryos c...

  20. The role of electrostatic interactions and solvent polarity on the 15N NMR shielding of azines

    Science.gov (United States)

    Modesto-Costa, Lucas; Gester, Rodrigo M.; Manzoni, Vinícius

    2017-10-01

    The nitrogen-15 nuclear magnetic resonance (15N NMR) shielding of azines is very sensitive to the chemical environment. Theoretically, specific interactions are important on the calculation of their spectroscopic properties. However, the choice of the solvent model for the description of NMR shielding constants is still a subject of discussion. In this context, we analyse the role of electrostatic interactions on 15N NMR shielding as function of solvent polarity using the sequential-Quantum Mechanics/Molecular Mechanics approach methodology. Excellent agreement with experimental data of the NMR shielding was obtained without the inclusion of explicit solvent molecules either for polar or non polar solvents.

  1. Accurate proteome-wide protein quantification from high-resolution 15N mass spectra.

    Science.gov (United States)

    Khan, Zia; Amini, Sasan; Bloom, Joshua S; Ruse, Cristian; Caudy, Amy A; Kruglyak, Leonid; Singh, Mona; Perlman, David H; Tavazoie, Saeed

    2011-12-19

    In quantitative mass spectrometry-based proteomics, the metabolic incorporation of a single source of 15N-labeled nitrogen has many advantages over using stable isotope-labeled amino acids. However, the lack of a robust computational framework for analyzing the resulting spectra has impeded wide use of this approach. We have addressed this challenge by introducing a new computational methodology for analyzing 15N spectra in which quantification is integrated with identification. Application of this method to an Escherichia coli growth transition reveals significant improvement in quantification accuracy over previous methods.

  2. Uptake and fate of hexahydro-1,3,5-trinitro-1,3,5-triazine (RDX) in coastal marine biota determined using a stable isotopic tracer, (15)N - [RDX].

    Science.gov (United States)

    Ballentine, Mark L; Ariyarathna, Thivanka; Smith, Richard W; Cooper, Christopher; Vlahos, Penny; Fallis, Stephen; Groshens, Thomas J; Tobias, Craig

    2016-06-01

    Hexahydro-1,3,5-trinitro-1,3,5-triazine (RDX) is globally one of the most commonly used military explosives and environmental contaminant. (15)N labeled RDX was added into a mesocosm containing 9 different coastal marine species in a time series experiment to quantify the uptake of RDX and assess the RDX derived (15)N retention into biota tissue. The (15)N attributed to munitions compounds reached steady state concentrations ranging from 0.04 to 0.67 μg (15)N g dw(-1), the bulk (15)N tissue concentration for all species was 1-2 orders of magnitude higher suggesting a common mechanism or pathway of RDX biotransformation and retention of (15)N. A toxicokinetic model was created that described the (15)N uptake, elimination, and transformation rates. While modeled uptake rates were within previous published values, elimination rates were several orders of magnitude smaller than previous studies ranging from 0.05 to 0.7 days(-1). These small elimination rates were offset by high rates of retention of (15)N previously not measured. Bioconcentration factors and related aqueous:organism ratios of compounds and tracer calculated using different tracer and non-tracer methods yielded a broad range of values (0.35-101.6 mL g(-1)) that were largely method dependent. Despite the method-derived variability, all values were generally low and consistent with little bioaccumulation potential. The use of (15)N labeled RDX in this study indicates four possible explanations for the observed distribution of compounds and tracer; each with unique potential implications for possible toxicological impacts in the coastal marine environment. Copyright © 2016 Elsevier Ltd. All rights reserved.

  3. Rotational spectrum of deuterated and 15N ethyl cyanides: CH3CHDCN and CH2DCH2CN and of CH3CH2C15N

    CERN Document Server

    Margulès, Laurent; Demyk, Karine; Tercero, Belen; Cernicharo, Jose; Sheng, M; Weidmann, M; Gripp, J; Mäder, H; Demaison, J

    2008-01-01

    Ethyl cyanide is an abundant molecule in hot molecular clouds. Lines from 13C isotopically substituted ethyl cyanide were identified in Orion. To enable the search and the possible detection of other isotopologues of ethyl cyanide in interstellar objects, we have studied the rotational spectrum of deuterated ethyl cyanide: CH2DCH2CN (in-plane and out-of-plane) and CH3CHDCN and the spectrum of15N substituted ethyl cyanide CH3CH2C15N. The rotational spectrum of each species in the ground state was measured in the microwave and millimeter-submillimeter wavelength range using a waveguide Fourier transform spectrometer (8 - 17 GHz) and a source-modulated spectrometer employing backward-wave oscillators (BWOs) (150 - 260 and 580 - 660 GHz). From the fitting procedure, accurate spectroscopic constants were derived for each of the species. These new sets of spectroscopic constants enable us to predict reliably the rotational spectrum (lines frequencies and intensities) in the 4-1000 GHz frequency range and for J and ...

  4. Carbon-rich presolar grains from massive stars. Subsolar 12C/13C and 14N/15N ratios and the mystery of 15N

    CERN Document Server

    Pignatari, M; Hoppe, P; Jordan, C J; Gibson, B K; Trappitsch, R; Herwig, F; Fryer, C; Hirschi, R; Timmes, F X

    2015-01-01

    Carbon-rich grains with isotopic anomalies compared to the Sun are found in primitive meteorites. They were made by stars, and carry the original stellar nucleosynthesis signature. Silicon carbide grains of Type X and C, and low-density graphites condensed in the ejecta of core-collapse supernovae. We present a new set of models for the explosive He shell and compare them with the grains showing 12C/13C and 14N/15N ratios lower than solar. In the stellar progenitor H was ingested into the He shell and not fully destroyed before the explosion. Different explosion energies and H concentrations are considered. If the SN shock hits the He-shell region with some H still present, the models can reproduce the C and N isotopic signatures in C-rich grains. Hot-CNO cycle isotopic signatures are obtained, including a large production of 13C and 15N. The short-lived radionuclides 22Na and 26Al are increased by orders of magnitude. The production of radiogenic 22Ne from the decay of 22Na in the He shell might solve the pu...

  5. Quantifying the production of dissolved organic nitrogen in headwater streams using 15N tracer additions

    Science.gov (United States)

    Laura T. Johnson; Jennifer L. Tank; Robert O. Hall; Patrick J. Mullholland; Stephen K. Hamilton; H. Maurice Valett; Jackson R. Webster; Melody J. Bernot; William H. McDowell; Bruce J. Peterson; Suzanne M. Thomas

    2013-01-01

    Most nitrogen (N) assimilation in lake and marine ecosystems is often subsequently released via autochthonous dissolved organic nitrogen (DON) production, but autochthonous DON production has yet to be quantified in flowing waters. We measured in-stream DON production following 24 h 15N-nitrate (NO3-...

  6. Nitrate Removal in Two Relict Oxbow Urban Wetlands: A 15N Mass-balance Approach

    Science.gov (United States)

    A 15N-tracer method was used to quantify nitrogen (N) removal processes in two relict oxbow wetlands located adjacent to the Minebank Run restored stream reach in Baltimore County (Maryland, USA) during summer 2009 and early spring 2010. A mass-balance approach was used to determ...

  7. Backbone dynamics of the EIAV-Tat protein from {sup 15}N relaxation studies

    Energy Technology Data Exchange (ETDEWEB)

    Ejchart, A.; Herrmann, F.; Roesch, P.; Sticht, H.; Willbold, D. [Bayreuth Univ., Bayreuth (Germany)

    1994-12-31

    The work investigates the mobility of EIAV-Tat protein backbone by measuring the relaxation parameters of the {sup 15}N nitrogens. High degree of the flexibility, non-typical of rigid, well structured proteins was shown. 3 refs, 2 figs.

  8. Monitoring the refinement of crystal structures with (15)N solid-state NMR shift tensor data.

    Science.gov (United States)

    Kalakewich, Keyton; Iuliucci, Robbie; Mueller, Karl T; Eloranta, Harriet; Harper, James K

    2015-11-21

    The (15)N chemical shift tensor is shown to be extremely sensitive to lattice structure and a powerful metric for monitoring density functional theory refinements of crystal structures. These refinements include lattice effects and are applied here to five crystal structures. All structures improve based on a better agreement between experimental and calculated (15)N tensors, with an average improvement of 47.0 ppm. Structural improvement is further indicated by a decrease in forces on the atoms by 2-3 orders of magnitude and a greater similarity in atom positions to neutron diffraction structures. These refinements change bond lengths by more than the diffraction errors including adjustments to X-Y and X-H bonds (X, Y = C, N, and O) of 0.028 ± 0.002 Å and 0.144 ± 0.036 Å, respectively. The acquisition of (15)N tensors at natural abundance is challenging and this limitation is overcome by improved (1)H decoupling in the FIREMAT method. This decoupling dramatically narrows linewidths, improves signal-to-noise by up to 317%, and significantly improves the accuracy of measured tensors. A total of 39 tensors are measured with shifts distributed over a range of more than 400 ppm. Overall, experimental (15)N tensors are at least 5 times more sensitive to crystal structure than (13)C tensors due to nitrogen's greater polarizability and larger range of chemical shifts.

  9. 15N NMR Spectroscopic Study on Nitrogen Forms in Humic Substances of Soils

    Institute of Scientific and Technical Information of China (English)

    WENQIXAIO; ZHUOSUNENG; 等

    2001-01-01

    Nitrogen forms of humic substances from a subalpine meadow soil,a lateritic red soil and a weathered cola and the effect of acid hydrolysis on N structures of soil humic substances were studied by using 15N cross-polarization magic angle spinning nuclear magnetic resonance(CPMAS NMR) spectroscopy,Of the detectable 15N-signal intensity in the spectra of soil humic substances 71%-79% may be attributed to amide groups ,10%-18% to aromatic/aliphatic amines and 6%-11% to indole-and pyrrole-like N.Whereas in the spectrum of the fulvic acid from weathered coal 46%,at least,of the total 15N-signal intensity might be assigned to pyrrole-like N,14% to aromatic/aliphatic amines,and the reamining intensities could not be assigned with certainty,Data on nonhydrolyzable reside of protein-sugar mixture and a 15N-labelled soil fulvic acid confirm the formation of nonhydrolyzable heterocyclic N during acid hydrolysis.

  10. The degree of urbanization across the globe is not reflected in the δ(15)N of seagrass leaves.

    Science.gov (United States)

    Christiaen, Bart; Bernard, Rebecca J; Mortazavi, Behzad; Cebrian, Just; Ortmann, Alice C

    2014-06-30

    Many studies show that seagrass δ(15)N ratios increase with the amount of urbanization in coastal watersheds. However, there is little information on the relationship between urbanization and seagrass δ(15)N ratios on a global scale. We performed a meta-analysis on seagrass samples from 79 independent locations to test if seagrass δ(15)N ratios correlate with patterns of population density and fertilizer use within a radius of 10-200 km around the sample locations. Our results show that seagrass δ(15)N ratios are more influenced by intergeneric and latitudinal differences than the degree of urbanization or the amount of fertilizer used in nearby watersheds. The positive correlation between seagrass δ(15)N ratios and latitude hints at an underlying pattern in discrimination or a latitudinal gradient in the (15)N isotopic signature of nitrogen assimilated by the plants. The actual mechanisms responsible for the correlation between δ(15)N and latitude remain unknown.

  11. Araucaria cunninghamii Seedling Response to Different Forms and Rates of 15N-Labelled Fertiliser

    Institute of Scientific and Technical Information of China (English)

    T.J.BLUMFIELD; XU Zhi-Hong

    2006-01-01

    Nitrogenous fertilisers are under consideration for promoting the growth of nursery-reared hoop pine (Araucaria cunninghamii Aiton ex A. Cunn) seedlings in the establishment phase of second rotation (2R) plantations. Using 15Nlabelled fertilisers, we investigated the effect of different forms (ammonium sulphate, ammonium nitrate, potassium nitrate and urea) and rates of application (0, 150 and 300 mg N kg-1 dried soil) of fertilisers on the growth, 15N recovery and carbon isotope composition (δ13C) of hoop pine seedlings in a 12-month glasshouse trial in southeast Queensland,Australia. The 15N-labelled fertilisers were applied to nursery-reared hoop pine seedlings, which were then grown in pots,containing ca. 1.2 kg dried soil, under well watered conditions for 12 months. Four seedlings from each treatment were harvested at 4-month intervals, divided into roots, stem and foliage, with a further subdivision for new and old foliage,and then analysed for 15N, total N, δ13C and total C. There was no significant response in the seedling growth to the form or rate of application of nitrogen (N) fertiliser within the 12-month period, indicating that the seedlings did not experience N deficiency when grown on second rotation hoop pine soils. While the combined 15N recovery from soil and plant remained at around 70% throughout the experiment, the proportion of 15N recovered from the plants increasing steadily over time. Nitrate containing fertilisers at 150 mg N kg-1 soil gradually increased seedling foliage δ13C over the 12-month period, indicating an increase in seedling water use efficiency.

  12. [Characteristics of urea 15N absorption, allocation, and utilization by sweet-cherry (Prunus avium L.)].

    Science.gov (United States)

    Zhao, Feng-Xia; Jiang, Yuan-Mao; Peng, Fu-Tian; Gao, Xiang-Bin; Liu, Bing-Hua; Wang, Hai-Yun; Zhao, Lin

    2008-03-01

    With five-year old 'Zaodaguo' sweet-cherry (Prunus avium L.) as test material, this paper studied the characteristics of its urea 15N absorption, allocation, and utilization when applied before bud-break. The results showed that the Ndff of different organs increased gradually with time, and was higher in fine roots and storage organs at full-blooming stage. At fruit core-hardening stage, the Ndff of long shoots and leaves increased quickly, reaching to 0.72% and 0.59% , respectively. From fruit core-hardening to harvesting stage, the Ndff of fruit had a rapid increase, with the peak (1.78%) at harvesting stage. After harvest, the Ndff of neonatal organs increased slowly while that of storage organs increased quickly. At full-blooming stage, the absorbed 15N in roots was firstly allocated to storage organs, with the highest allocation rate (54.91%) in large roots. At fruit core-hardening stage, the allocation rate in fine roots and storage organs decreased from 85.43% to 55.11%, while that in neonatal branches and leaves increased to 44.89%. At harvesting stage, the allocation rate in different organs had no significant change, but after harvest, the absorbed 15N had a rapid translocation to storage organs, and the allocation rate in fine roots and storage organs reached the highest (72.26%) at flower bud differentiation stage. The 15N allocation rate in neonatal branches and leaves at flower bud differentiation stage was decreased by 19.31%, compared with that at harvesting stage. From full-blooming to flower bud differentiation stage, the utilization rate of urea 15N was increasing, and reached the peak (16.86%) at flower bud differentiation stage.

  13. Interaction and transport of cysteamine (MEA) through membrane models. {sup 15}N-NMR et {sup 1}H-NMR; Interaction et transport de la cysteamine (MEA) a travers des membranes modeles. Etude par {sup 15}N-RMN et {sup 1}H-RMN

    Energy Technology Data Exchange (ETDEWEB)

    Lagoueyte, C.; Subra, G.; Bonnet, P.A.; Chapat, J.P.; Debouzy, J.C.; Fauvelle, F.; Berleur, F.; Roman, V.; Fatome, M.; Fernandez, J.P.

    1995-12-31

    We investigated by {sup 15}N-NMR the interactions of [{sup 15}N]-MEA, a radio-protecting aminothiol, with model membranes (SUVs and LUVs) of egg yolk phosphatidylcholine and phosphatidic acid. We prepared LUVs with a pH gradient between the intravesicular space and the bulk medium. Even though the external pH was low, MEA penetrates into the vesicles. With SUVs, {sup 1}H-NMR revealed that the interactions of unlabeled MEA within the hydrophobic core of the bilayer vary with external pH value. (author). 5 refs.

  14. Food web structure of the epibenthic and infaunal invertebrates on the Catalan slope (NW Mediterranean): Evidence from δ 13C and δ 15N analysis

    Science.gov (United States)

    Fanelli, E.; Papiol, V.; Cartes, J. E.; Rumolo, P.; Brunet, C.; Sprovieri, M.

    2011-01-01

    The food-web structure of the epibenthic and infaunal invertebrates on the continental slope of the Catalan Sea (Balearic basin, NW Mediterranean) was investigated using carbon and nitrogen stable isotopes on a total of 34 species, and HPLC pigment analyses for three key species. Samples were collected close to Barcelona (NE Iberian Peninsula), between 650 and 800 m depth and between February 2007 and February 2008. Mean δ 13C values ranged from -21.0‰ (small Calocaris macandreae and Amphipholis squamata) to -14.5‰ ( Sipunculus norvegicus). Values of δ 15N ranged from 4.0‰ ( A. squamata) to 12.1‰ ( Molpadia musculus). The stable isotope ratios of benthic fauna displayed a continuum of values (e.g. δ 15N range of 8‰), confirming a wide spectrum of feeding strategies (from active suspension feeders to predators) and complex food webs. According to the available information on diets of benthic fauna, the lowest values were found for surface deposit feeders (small C. macandrae and the two ophiuroids A. squamata and Amphiura chiajei) and active suspension feeders ( Abra longicallus and Scalpellum scalpellum) feeding on different sizes of particulate organic matter (POM), among which small particles may exhibit lower δ 15N. High annual mean δ 15N values were found among sub-surface deposit feeders, exploiting refractory or frequently recycled organic matter that is enriched in δ 15N. Carnivorous polychaetes ( Nephtys spp., Oenonidae and Polynoidae) and large decapods ( Geryon longipes and Paromola cuvieri) also displayed high δ 15N values. δ 13C ranges were particularly wide among surface deposit feeders (ranging from -21.0‰ to -16.4‰), suggesting exploitation of POM of both terrigenous and oceanic origins. Correlation between δ 13C and δ 15N was generally weak, indicating multiple carbon sources, likely due to the consumption of different kinds of sinking particles (e.g. marine snow, phytodetritus, etc.), sedimented and frequently recycled POM

  15. Leaf δ15N as an indicator of arbuscular mycorrhizal nitrogen uptake in a coastal-plain forest (restinga forest) at Southeastern Brazil

    Science.gov (United States)

    Mardegan, S. F.; Valadares, R.; Martinelli, L.

    2013-12-01

    Restinga diversity contrasts with a series of adverse environmental conditions that constrain their development, including nutrient limitation. In this sense, the mutualistic symbiosis between plants and arbuscular mycorrhizal fungi (AMF) may contribute in nutrient acquisition, including nitrogen. However, this association deeply affects plant nitrogen isotopic composition (δ15N), since assimilation processes and biochemical reactions within the fungi may reflect in a delivered product with an isotopic composition about 8 to 10 ‰ lower than that observed at the fungal symbiont per se. Here we assessed if the association with AMF affects δ15N values of plant species from a coastal-plain forest (restinga forest) at Southeastern Brazil. Accordingly, we analyzed the nutritional and isotopic compositions from ecosystem key-compartments (soil, litter and leaves), relating plant δ15N with the colonization rates. The study was carried out in a permanent plot (1 ha) at a coastal-plain forest (restinga forest) at the Serra do Mar State Park, SP, Brazil. Sampled vegetation is characterized by the lack of a well-defined stratification and a rather open canopy. It also comprises trees ranging from 10 to 15-m high. Soils are deep and sandy, being characterized by high acidity, nutrient deficiency and a dense litter cover. We randomly collected five samples (250 mg) from topsoil (0-10 cm) and five to ten leaves from individuals belonging to 16 plant species of high relevance within the site (IVI index). We also collected superficial (0-10 cm depth) fine roots (5 g) and 13 samples (100 g) of fine litter next to the individuals sampled. Soil samples were air-dried, sieved, homogenized and used in the physical-chemical characterization. The remainder was ground to a fine powder to determine nitrogen concentrations and δ15N values. Leaves were dried at 50 °C, finely milled and used for the determination of nitrogen concentrations, C/N ratios and δ15N values. Root samples were

  16. Estimation of enthalpy data for reactions involving gas phase ions utilizing lattice potential energies: fluoride ion affinities (FIA) and pF- values of mSbF5(l) and mSbF5(g) (m = 1, 2, 3), AsF5(g), AsF5.SO2(c). Standard enthalpies of formation: Delta(f)H degrees (SbmF5m+1)(-),g) (m = 1, 2, 3), Delta(f)H degrees (AsF6(-),g), and Delta(f)H degrees (NF4+,g).

    Science.gov (United States)

    Jenkins, H Donald Brooke; Roobottom, H K; Passmore, Jack

    2003-05-01

    Fluoride ion affinity (FIA) values (and the associated pF(-) values) are difficult to establish experimentally for pentafluorides of arsenic and antimony. Our approach, utilizing estimated lattice potential energies, provides a further opportunity to establish this data for liquid (and gaseous) SbF(5) and gaseous AsF(5) which compliments values obtained using ab initio routes for monomeric gas phase molecules and adds to results based on rigorous methods. A strategy is developed whereby construction of (multiple) Born-Fajans-Haber cycles centered around the (target) FIA reaction of interest yield a plethora of estimates for the enthalpy change of interest. This general approach is illustrated here by specific estimation of some experimentally based FIA values of SbF(5) and AsF(5). FIA values/kJ mol(-1) and pF- values estimated in this paper are FIA(SbF(5),l) approximately equal to -475 (+/-63), pF-(SbF(5),l) = 11.4 (+/-1.5); FIA(SbF(5),g) approximately equal to -506 (+/-63), pF-(SbF(5),g) = 12.4 (+/-1.5); FIA(2SbF(5),l) approximately equal to -609 (+/-63), pF- (2SbF(5),l) = 14.6 (+/-1.5); FIA (2SbF(5),g) approximately equal to -671 (+/-63), pF- (2SbF(5),g) = 16.0 (+/-1.5); FIA (3SbF(5),l) approximately -635 (+/-39), pF(-) (3SbF(5),l) = 15.2 (+/-0.9); FIA(3SbF(5),g) approximately -728 (+/-39), pF(-) (3SbF(5),g) = 17.4 (+/-0.9); FIA(AsF(5),g) approximately equal to -421 (+/-22), pF(-) (AsF(5),g) = 10.1 (+/- 0.5); and FIA (AsF(5).SO(2),s) approximately equal to -390 (+/-22), pF(-) (AsF(5).SO(2),s) = 9.3 (+/-0.5). Related standard enthalpies of formation (in kJ mol(-1)) are also assigned: Delta(f)H degrees (SbF(6)(-),g) approximately equal to -2075 (+/-52); Delta(f)H degrees (Sb(2)F(11)(-),g) approximately equal to -3520 (+/-63); Delta(f)H degrees (Sb(3)F(16)(-),g) approximately equal to -4874 (+/-39); Delta(f)H degrees (NF(4)(+),g) approximately equal to 903 (+/-32); Delta(f)H degrees (AsF(6)(-),g) approximately equal to -1907 (+/-22).

  17. A new organic reference material, L-glutamic acid, USGS41a, for δ13C and δ15N measurements − a replacement for USGS41

    Science.gov (United States)

    Qi, Haiping; Coplen, Tyler B.; Mroczkowski, Stanley J.; Brand, Willi A.; Brandes, Lauren; Geilmann, Heike; Schimmelmann, Arndt

    2016-01-01

    RationaleThe widely used l-glutamic acid isotopic reference material USGS41, enriched in both 13C and 15N, is nearly exhausted. A new material, USGS41a, has been prepared as a replacement for USGS41.MethodsUSGS41a was prepared by dissolving analytical grade l-glutamic acid enriched in 13C and 15N together with l-glutamic acid of normal isotopic composition. The δ13C and δ15N values of USGS41a were directly or indirectly normalized with the international reference materials NBS 19 calcium carbonate (δ13CVPDB = +1.95 mUr, where milliurey = 0.001 = 1 ‰), LSVEC lithium carbonate (δ13CVPDB = −46.6 mUr), and IAEA-N-1 ammonium sulfate (δ15NAir = +0.43 mUr) and USGS32 potassium nitrate (δ15N = +180 mUr exactly) by on-line combustion, continuous-flow isotope-ratio mass spectrometry, and off-line dual-inlet isotope-ratio mass spectrometry.ResultsUSGS41a is isotopically homogeneous; the reproducibility of δ13C and δ15N is better than 0.07 mUr and 0.09 mUr, respectively, in 200-μg amounts. It has a δ13C value of +36.55 mUr relative to VPDB and a δ15N value of +47.55 mUr relative to N2 in air. USGS41 was found to be hydroscopic, probably due to the presence of pyroglutamic acid. Experimental results indicate that the chemical purity of USGS41a is substantially better than that of USGS41.ConclusionsThe new isotopic reference material USGS41a can be used with USGS40 (having a δ13CVPDB value of −26.39 mUr and a δ15NAir value of −4.52 mUr) for (i) analyzing local laboratory isotopic reference materials, and (ii) quantifying drift with time, mass-dependent isotopic fractionation, and isotope-ratio-scale contraction for isotopic analysis of biological and organic materials. Published in 2016. This article is a U.S. Government work and is in the public domain in the USA.

  18. A new organic reference material, l-glutamic acid, USGS41a, for δ(13) C and δ(15) N measurements - a replacement for USGS41.

    Science.gov (United States)

    Qi, Haiping; Coplen, Tyler B; Mroczkowski, Stanley J; Brand, Willi A; Brandes, Lauren; Geilmann, Heike; Schimmelmann, Arndt

    2016-04-15

    The widely used l-glutamic acid isotopic reference material USGS41, enriched in both (13) C and (15) N, is nearly exhausted. A new material, USGS41a, has been prepared as a replacement for USGS41. USGS41a was prepared by dissolving analytical grade l-glutamic acid enriched in (13) C and (15) N together with l-glutamic acid of normal isotopic composition. The δ(13) C and δ(15) N values of USGS41a were directly or indirectly normalized with the international reference materials NBS 19 calcium carbonate (δ(13) CVPDB = +1.95 mUr, where milliurey = 0.001 = 1 ‰), LSVEC lithium carbonate (δ(13) CVPDB = -46.6 mUr), and IAEA-N-1 ammonium sulfate (δ(15) NAir = +0.43 mUr) and USGS32 potassium nitrate (δ(15) N = +180 mUr exactly) by on-line combustion, continuous-flow isotope-ratio mass spectrometry, and off-line dual-inlet isotope-ratio mass spectrometry. USGS41a is isotopically homogeneous; the reproducibility of δ(13) C and δ(15) N is better than 0.07 mUr and 0.09 mUr, respectively, in 200-μg amounts. It has a δ(13) C value of +36.55 mUr relative to VPDB and a δ(15) N value of +47.55 mUr relative to N2 in air. USGS41 was found to be hydroscopic, probably due to the presence of pyroglutamic acid. Experimental results indicate that the chemical purity of USGS41a is substantially better than that of USGS41. The new isotopic reference material USGS41a can be used with USGS40 (having a δ(13) CVPDB value of -26.39 mUr and a δ(15) NAir value of -4.52 mUr) for (i) analyzing local laboratory isotopic reference materials, and (ii) quantifying drift with time, mass-dependent isotopic fractionation, and isotope-ratio-scale contraction for isotopic analysis of biological and organic materials. Published in 2016. This article is a U.S. Government work and is in the public domain in the USA. Published in 2016. This article is a U.S. Government work and is in the public domain in the USA.

  19. Proton-detected 3D (15)N/(1)H/(1)H isotropic/anisotropic/isotropic chemical shift correlation solid-state NMR at 70kHz MAS.

    Science.gov (United States)

    Pandey, Manoj Kumar; Yarava, Jayasubba Reddy; Zhang, Rongchun; Ramamoorthy, Ayyalusamy; Nishiyama, Yusuke

    2016-01-01

    Chemical shift anisotropy (CSA) tensors offer a wealth of information for structural and dynamics studies of a variety of chemical and biological systems. In particular, CSA of amide protons can provide piercing insights into hydrogen-bonding interactions that vary with the backbone conformation of a protein and dynamics. However, the narrow span of amide proton resonances makes it very difficult to measure (1)H CSAs of proteins even by using the recently proposed 2D (1)H/(1)H anisotropic/isotropic chemical shift (CSA/CS) correlation technique. Such difficulties due to overlapping proton resonances can in general be overcome by utilizing the broad span of isotropic chemical shifts of low-gamma nuclei like (15)N. In this context, we demonstrate a proton-detected 3D (15)N/(1)H/(1)H CS/CSA/CS correlation experiment at fast MAS frequency (70kHz) to measure (1)H CSA values of unresolved amide protons of N-acetyl-(15)N-l-valyl-(15)N-l-leucine (NAVL).

  20. Temporal and spatial variations of δ15N and δ18O for atmospheric N2O above the oceanic surface from Shanghai to Antarctica

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    During the 22nd Chinese Antarctic Research Expedition (CHINARE-22), the atmospheric gas samples above the oceanic surface and near the surface were collected on the track for the scientific ship "Xuelong" and on Millor Peninsula of eastern Antarctica, respectively, using the Tedlar gas bags. Every day the sampling times were 10:00 and 22:00 (local time), respectively. In the laboratory, high-precision measurement of the isotopic compositions for N2O in these gas samples was conducted using Thermo Finnigan MAT-253 Isotopic Mass Spectrometer with a fully automated interface for the pre-GC concen-tration (PreCon) of trace gases. The temporal and spatial variations of δ 15N and δ 18O in atmospheric N2O were analyzed. The mean δ 15N and δ 18O-N2O values above the oceanic surface were (7.21±0.50)‰ and (44.52±0.52)‰, respectively. From 30°N to Antarctica, the δ 15N (6.05‰―7.88‰) linearly increased with the rate of about 0.01‰ with the latitude while the δ 18O (43.05‰―48.78‰) showed a large fluctua-tion. The δ 15N negatively correlated with air temperature and N2O concentration, and slightly positively correlated with δ 18O. The summertime variations of δ 15N and δ 18O-N2O appeared the same trend on Millor Peninsula of eastern Antarctica. They significantly positively correlated with each other and negatively with N2O concentration. The δ 15N and δ 18O-N2O at different sites averaged (7.42±0.35)‰ and (44.69±0.49)‰, respectively, slightly higher than those above the oceanic surface, significantly higher than those of atmospheric N2O in the low-latitude regions of Northern Hemisphere. The predominant factors affecting the spatial variations of δ 15N and δ 18O values were also discussed. The isotopic data given in this study can help to investigate the global and regional N2O budgets.

  1. Temporal and spatial variations of δ15N and δ18O for atmospheric N2O above the oceanic surface from Shanghai to Antarctica

    Institute of Scientific and Technical Information of China (English)

    ZHU RenBin; LIU YaShu; XU Hua; MA Jing; SUN LiGuang

    2008-01-01

    During the 22nd Chinese Antarctic Research Expedition (CHINARE-22), the atmospheric gas samples above the oceanic surface and near the surface were collected on the track for the scientific ship "Xuelong" and on Millor Peninsula of eastern Antarctica, respectively, using the Tedlar gas bags. Every day the sampling times were 10:00 and 22:00 (local time), respectively. In the laboratory, high-precision measurement of the isotopic compositions for N2O in these gas samples was conducted using Thermo Finnigan MAT-253 Isotopic Mass Spectrometer with a fully automated interface for the pre-GC concen-tration (PreCon) of trace gases. The temporal and spatial variations of δ15N and δ18O in atmospheric N2O were analyzed. The mean δ15N and δ18O-N2O values above the oceanic surface were (7.21±0.50)‰ and (44.52±0.52)‰, respectively. From 30°N to Antarctica, the δ15N (6.05%o-7.88‰) linearly increased with the rate of about 0.01‰ with the latitude while the δ18o (43.05‰-48.78‰) showed a large fluctua-tion. The δ15N negatively correlated with air temperature and N2O concentration, and slightly positively correlated with δ18O. The summertime variations of δ15N and δ18O-N2O appeared the same trend on Millor Peninsula of eastern Antarctica. They significantly positively correlated with each other and negatively with N2O concentration. The δ15N and δ18O-N2O at different sites averaged (7.42±0.35)‰ and (44.69±0.49)‰, respectively, slightly higher than those above the oceanic surface, significantly higher than those of atmospheric N2O in the low-latitude regions of Northern Hemisphere. The predominant factors affecting the spatial variations of δ15N and δ180 values were also discussed. The isotopic data given in this study can help to investigate the global and regional N2O budgets.

  2. Characterization of Humic Fractions in a 15N-labelled Soil by Solid by State-State 13C and 15N NMR

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    Five humic fractions were obtained from a uniformly 15N-labelled soil by extraction with 0.1 mol L-1 Na4P2O7,0.1 mol L-1 NaOH,and HF/HC1-0.1 mol L-1 NaOH,consecutively,and analyzed by 13C and 15N CPMAS NMR (croas polarization and magic angle spinning nuclear magnetic resonance).Compared with those of native soils humic fractions studied as a whole contained more alkyls,methoxyls and O-alkyls,being 27%~36%,17%~21% and 36%~40%,respectively,but fewer aromatics and carboxyls (being 14%~20% and 13%~90%,respectively).Among those humic fractions,the humic acid (HA) and fulvic acid (FA) extracted by 0.1 mol L-1 Na4P2O7 contained slightly more carboxyls than corresponding humic fractions extracted by 0.1 mol L-1 NaOH,and the HA extracted by 0.1 mol L-1 NaOH after treatment with HF/HC1 contained the least aromatics and carboxyls. The distribution of nitrogen functional groups of soil humic fractions studied was quite similar to each other and also quite similar to that of humic fraction from native soils.More than 75% of total N in each fraction was in amide form,with 9%~13% present as aromatic and/or aliphatic amines and the remainder as heterocyclic N.

  3. Fertilizer {sup 15}N balance in a coffee cropping system: a case study in Brazil

    Energy Technology Data Exchange (ETDEWEB)

    Fenilli, Tatiele Anete Bergamo [Universidade Regional de Blumenau (URB), SC (Brazil). Dept. de Engenharia Florestal]. E-mail: tfenilli@furb.br; Reichardt, Klaus; Bacchi, Osny Oliveira Santos [Centro de Energia Nuclear na Agricultura (CENA/USP), Piracicaba, SP (Brazil). Lab. de Fisica do Solo]. E-mails: klaus@cena.usp.br; osny@cena.usp.br; Favarin, Jose Laercio [Escola Superior de Agricultura Luiz de Queiroz (ESALQ/USP), Piracicaba, SP (Brazil). Dept. de Producao Vegetal; Silva, Adriana Lucia [Centro de Tecnologia Canavieira (CTC), Piracicaba, SP (Brazil). Fazenda Santo Antonio]. E-mail: adriana.silva@ctc.com.br; Timm, Luis Carlos [Universidade Federal de Pelotas (UFPel), RS (Brazil). Dept. de Engenharia Rural]. E-mail: lcartimm@yahoo.com.br

    2008-07-15

    Knowledge about the fate of fertilizer nitrogen in agricultural systems is essential for the improvement of management practices in order to maximize nitrogen (N) recovery by the crop and reduce N losses from the system to a minimum. This study involves fertilizer management practices using the {sup 15}N isotope label applied in a single rate to determine the fertilizer-N balance in a particular soil-coffee-atmosphere system and to deepen the understanding of N plant dynamics. Five replicates consisting of plots of about 120 plants each were randomly defined within a 0.2 ha coffee plantation planted in 2001, in Piracicaba, SP, Brazil. Nine plants of each plot were separated in sub-plots for the {sup 15}N balance studies and treated with N rates of 280 and 350 kg ha-1 during 2003/2004 and 2004/ 2005, respectively, both of them as ammonium sulfate enriched to a {sup 15}N abundance of 2.072 atom %. Plant shoots were considered as separate parts: the orthotropic central branch, productive branches, leaves of productive branches, vegetative branches, leaves of vegetative branches and fruit. Litter, consisting of dead leaves accumulated below the plant canopy, was measured by the difference between leaves at harvest and at the beginning of the following flowering. Roots and soil were sampled down to a depth of 1.0 at intervals of 0.2 m. Samples from the isotopic sub-plots were used to evaluate total N and {sup 15}N, and plants outside sub-plots were used to evaluate dry matter. Volatilization losses of NH{sub 3} were estimated using special collectors. Leaching of fertilizer-N was estimated from deep drainage water fluxes and {sup 15}N concentrations of the soil solution at 1 m soil depth. At the end of the 2-year evaluation, the recovery of {sup 15}N applied as ammonium sulfate was 19.1 % in aerial plant parts, 9.4 % in the roots, 23.8 % in the litter, 26.3 % in the fruit and 12.6 % remaining in the 0-1.0 m soil profile. Annual leaching and volatilization losses were

  4. δ15N measurement of organic and inorganic substances by EA-IRMS: a speciation-dependent procedure.

    Science.gov (United States)

    Gentile, Natacha; Rossi, Michel J; Delémont, Olivier; Siegwolf, Rolf T W

    2013-01-01

    Little attention has been paid so far to the influence of the chemical nature of the substance when measuring δ(15)N by elemental analysis (EA)-isotope ratio mass spectrometry (IRMS). Although the bulk nitrogen isotope analysis of organic material is not to be questioned, literature from different disciplines using IRMS provides hints that the quantitative conversion of nitrate into nitrogen presents difficulties. We observed abnormal series of δ(15)N values of laboratory standards and nitrates. These unexpected results were shown to be related to the tailing of the nitrogen peak of nitrate-containing compounds. A series of experiments were set up to investigate the cause of this phenomenon, using ammonium nitrate (NH(4)NO(3)) and potassium nitrate (KNO(3)) samples, two organic laboratory standards as well as the international secondary reference materials IAEA-N1, IAEA-N2-two ammonium sulphates [(NH(4))(2)SO(4)]-and IAEA-NO-3, a potassium nitrate. In experiment 1, we used graphite and vanadium pentoxide (V(2)O(5)) as additives to observe if they could enhance the decomposition (combustion) of nitrates. In experiment 2, we tested another elemental analyser configuration including an additional section of reduced copper in order to see whether or not the tailing could originate from an incomplete reduction process. Finally, we modified several parameters of the method and observed their influence on the peak shape, δ(15)N value and nitrogen content in weight percent of nitrogen of the target substances. We found the best results using mere thermal decomposition in helium, under exclusion of any oxygen. We show that the analytical procedure used for organic samples should not be used for nitrates because of their different chemical nature. We present the best performance given one set of sample introduction parameters for the analysis of nitrates, as well as for the ammonium sulphate IAEA-N1 and IAEA-N2 reference materials. We discuss these results considering the

  5. Spatial variation in the strength of mutualism between a jumping spider and a terrestrial bromeliad: Evidence from the stable isotope 15N

    Science.gov (United States)

    Romero, Gustavo Q.; Vasconcellos-Neto, João; Trivelin, Paulo C. O.

    2008-05-01

    Psecas chapoda, a neotropical jumping spider strictly associated with the terrestrial bromeliad Bromelia balansae in cerrados and semi-deciduous forests in South America, effectively contributes to plant nutrition and growth. In this study, our goal was to investigate if spider density caused spatial variations in the strength of this spider-plant mutualism. We found a positive significant relationship between spider density and δ15N values for bromeliad leaves in different forest fragments. Open grassland Bromeliads were associated with spiders and had higher δ15N values compared to forest bromeliads. Although forest bromeliads had no association with spiders their total N concentrations were higher. These results suggest that bromeliad nutrition is likely more litter-based in forests and more spider-based in open grasslands. This study is one of the few to show nutrient provisioning and conditionality in a spider-plant system.

  6. Early-stage changes in natural (13)C and (15)N abundance and nutrient dynamics during different litter decomposition.

    Science.gov (United States)

    Gautam, Mukesh Kumar; Lee, Kwang-Sik; Song, Byeong-Yeol; Lee, Dongho; Bong, Yeon-Sik

    2016-05-01

    Decomposition, nutrient, and isotopic (δ(13)C and δ(15)N) dynamics during 1 year were studied for leaf and twig litters of Pinus densiflora, Castanea crenata, Erigeron annuus, and Miscanthus sinensis growing on a highly weathered soil with constrained nutrient supply using litterbags in a cool temperate region of South Korea. Decay constant (k/year) ranged from 0.58 to 1.29/year, and mass loss ranged from 22.36 to 58.43 % among litter types. The results demonstrate that mass loss and nutrient dynamics of decomposing litter were influenced by the seasonality of mineralization and immobilization processes. In general, most nutrients exhibited alternate phases of rapid mineralization followed by gradual immobilization, except K, which was released throughout the field incubation. At the end of study, among all the nutrients only N and P showed net immobilization. Mobility of different nutrients from decomposing litter as the percentage of initial litter nutrient concentration was in the order of K > Mg > Ca > N ≈ P. The δ(13)C (0.32-6.70 ‰) and δ(15)N (0.74-3.90 ‰) values of residual litters showed nonlinear increase and decrease, respectively compared to initial isotopic values during decomposition. Litter of different functional types and chemical quality converged toward a conservative nutrient use strategy through mechanisms of slow decomposition and slow nutrient mobilization. Our results indicate that litter quality and season, are the most important regulators of litter decomposition in these forests. The results revealed significant relationships between litter decomposition rates and N, C:N ratio and P, and seasonality (temperature). These results and the convergence of different litters towards conservative nutrient use in these nutrient constrained ecosystems imply optimization of litter management because litter removal can have cascading effects on litter decomposition and nutrient availability in these systems.

  7. Fate of 15N and 14C from labelled plant material

    DEFF Research Database (Denmark)

    Rasmussen, Jim; Gjettermann, Birgitte; Eriksen, Jørgen;

    2008-01-01

    strength of labelled plant residues in dissolved inorganic N (DIN) and dissolved organic N (DON) in pore water from the plough layer, and (ii) the plant uptake of organically bound N. Litterbags containing 14C- and 15N-labelled ryegrass or clover roots or leaves were inserted into the sward of a ryegrass......–clover mixture in early spring. The fate of the released 14C and 15N was monitored in harvested biomass, roots, soil, and pore water percolating from the plough layer. No evidence of plant uptake of dual-labelled organic compounds from the dual-labelled residues could be observed. N in pore water from the plough...... water originating from plant residues only constituted 1.5% of the total dissolved N from the plough layer....

  8. Study of organic N transformation in red soils by 15N tracer method

    Institute of Scientific and Technical Information of China (English)

    YeQing-Fu; ZhangQin-Zheng; 等

    1997-01-01

    Uniformly 15N-labelled ryegrass was used to investigate NH4+-production,microbial transformation and humification of organic N in two types of red soils by incubating the soils amended with labelled material.The results showed that there was little significant difference in biomass N transformation in the tested solis between 15N tracer method and conventional method,but the amount of NH4++-N released form the ryegrass in the clayey soil than in the sandy soil at all sampling time .By 120d of incubation,humified N was less than 10% of the amount of the applied N in two types of red soils and the amount of residual N in the clayey red soil was obviously higher than that in the sandy red soil.

  9. Capture cross sections of 15N(n, {\\gamma})16N at astrophysical energies

    CERN Document Server

    Fan, Guang-wei; Sheng, Zong-qiang; Tian, Feng; Wang, Jun; Zhang, Chao

    2016-01-01

    We have reanalyzed reaction cross sections of 16N on 12C target. The nucleon density distribution of 16N, especially surface density distribution, was extracted using the modified Glauber model. On the basis of dilute surface densities, the discussion of 15N(n, {\\gamma})16N reaction was performed within the framework of the direct capture reaction mechanism. The calculations agreed quite well with the experimental data.

  10. {sup 15}N uptake from manure and fertilizer sources by three consecutive crops under controlled conditions

    Energy Technology Data Exchange (ETDEWEB)

    Quiroga Garza, Hector Mario, E-mail: quiroga.mario@inifap.gob.m [Instituto Nacional de Investigaciones Forestales, Agricolas y Pecuarias (INIFAP), Coahuila (Mexico); Delgado, Jorge A.; Wong, Jose Antonio Cueto, E-mail: jorge.delgado@ars.usda.go, E-mail: cueto.jose@inifap.gob.m [United States Dept. of Agriculture (USDA), Fort Collins, CO (United States). Agricultural Research Service. Soil Plant Nutrient Research Unit; Lindemann, William C., E-mail: wlindema@nmsu.ed [New Mexico State University (NMST), Las Cruces, NM (United States). Dept. Agronomy and Horticulture

    2009-09-15

    There are several regions of the world where soil N analysis and/or N budgets are not used to determine how much N to apply, resulting in higher than needed N inputs, especially when manure is used. One such region is the North Central 'La Comarca Lagunera', one of the most important dairy production areas of Mexico. We conducted a unique controlled greenhouse study using {sup 15}N fertilizer and {sup 15}N isotopic-labeled manure that was labeled under local conditions to monitor N cycling and recovery under higher N inputs. The manure-N treatment was applied only once and was incorporated in the soil before planting the first forage crop at an equivalent rate of 30, 60 and 120 Mg ha{sup -1} dry manure. The {sup 15}N treatments were equivalent to 120 and 240 kg ha{sup -1} (NH{sub 4}){sub 2}SO{sub 4}-N for each crop. The total N fertilizer for each N fertilized treatment were 360, and 720 kg ha{sup -1} N. We found very low N recoveries: about 9 % from the manure N inputs, lower than the 22 to 25 % from the fertilizer N inputs. The manure N recovered below ground in soil and roots ranged from 82 to 88 %. The low recoveries of N by the aboveground and low soil inorganic nitrate (NO{sup 3}-N) and ammonium (NH{sub 4}-N) content after the third harvested suggested that most of the {sup 15}N recovered below ground was in the soil organic form. The losses from manure N inputs ranged from 3 to 11 %, lower than the 34 to 39 % lost from fertilizer N sources. Our study shows that excessive applications of manure or fertilizer N that are traditionally used in this region will not increase the rate of N uptake by aboveground compartment but will increase the potential for N losses to the environment. (author)

  11. Chemienzymatic synthesis of Uridine. Nucleotides labeled with [15N] and [13C

    DEFF Research Database (Denmark)

    Gilles, Anne-Marie; Cristea, Ioan; Palibroda, Nicolae

    1995-01-01

    +necessary for the oxidation of glucose 6-phosphate and 6-phosphogluconate was recycled by glutamate dehydrogenase and excess of ammonia and a-oxoglutarate. Despite the number and complexity of the enzymatic steps, the synthesis of [15N,13C]UTP is straightforward with an overall yield exceeding 60%. This method, extended...... and diversified to the synthesis of all natural ribonucleotides, is a more economical alternative for obtaining nucleic acids for structural analysis by heteronuclear NMR spectroscopy....

  12. ~(15)N Isotope Used for Study of Groundwater Nitrogen Pollution in Shijiazhuang City, China

    Institute of Scientific and Technical Information of China (English)

    2004-01-01

    Shijiazhuang City is the capital of Hebei province, China. Groundwater is the major water supply source for living and industry need of the city. Due to a rapid increase of population and development of industry and agriculture, a series of groundwater environmental problems are created. In the paper, the situation of groundwater pollution in Shijiazhuang city is reported. Based on the groundwater chemical data and ~(15)N measurement results both on groundwater and soils, the reason of groundwater nitra...

  13. Stellar delta matter with delta-meson coupling constants constrained by QCD sum rule

    Energy Technology Data Exchange (ETDEWEB)

    Silva, Antonio Ferreira da [Secretaria de Educacao, Cultura e Desportos do Estado de Roraima (SECD/RR), Boa Vista, RR (Brazil); Oliveira, Jose Carlos Teixeira de [Universidade Federal de Roraima (UFRR), Boa Vista, RR (Brazil); Rodrigues, Hilario [Centro Federal de Educacao Tecnologica (CEFET-RJ), Rio de Janeiro, RJ (Brazil); Duarte, Sergio Barbosa [Centro Brasileiro de Pesquisas Fisicas (CBPF), Rio de Janeiro, RJ (Brazil); Chiapparini, Marcelo [Universidade do Estado do Rio de Janeiro (UERJ), RJ (Brazil)

    2010-07-01

    The considerable presence of delta-resonances (30% of baryonic population) in the dense phase of relativistic heavy ion collisions leads to a great interest in the study of the delta matter formation in the deep interior of compact stars. In the present work we determine the equation of state and the population of baryons and leptons and discuss the effects of the baryon-meson coupling constants to the formation of delta matter in the stellar medium. We use the non-linear Walecka model consisting of the octet of baryons of spin 1=2 (n, p, {Lambda}{sup 0}, {Sigma}{sup -}, {Sigma}{sup 0}, {Sigma}{sup +}, {Xi}{sup -}, {Xi}{sup 0}) and baryonic resonances of spin 3=2, represented by the delta resonances ({Delta}{sup -}, ({Delta}{sup 0}, ({Delta}{sup +}, ({Delta}{sup ++}) and {Omega}{sup -}, in the baryonic sector. In the leptonic sector we consider the electrons and muons. The coupling constants between the hyperons {Lambda}, {Sigma}, and {Xi} and the mesons {omega} and {rho} are fixed by using SU(6) symmetry, while the hyperons-{sigma} coupling constants are constrained by the consistence of the hypernuclear potential in the nuclear matter with hypernuclear data. In addition, we use the finite density QCD sum rule to determine the possible values of delta-meson coupling constants. (author)

  14. Trophic relationships in the Changjiang River estuarine salt marshes: preliminary investigation from δ13C and δ15N analysis

    Institute of Scientific and Technical Information of China (English)

    QUAN Weimin; HUANG Danqing; CHU Tianjiang; SHENG Qiang; FU Cuizhang; CHEN Jiakuan; WU Jihua

    2009-01-01

    To obtain information on food web structure in salt marshes of the Changjiang (Yangtze) River Estuary, the δ13C and δ15 N values of primary producers and consumers were determined. The mean δ13C values of 31 dominant consumers ranged from -23.13%c to -14.37%0. Except for several species (Eriocheir sinensis, Sinonovacula constricta and Potamocorbula ustulata), consumers had interme-diate δ13C values between those of benthic microalgae and Spartina alterniflora. The mean δ154N values of 31 dominant consumers varied between 6.87%0 and 13.33%0, which indicate three trophic levels in salt marshes of the Changjiang River Estuary. A total of 18 macroinvertebrates species and four fish species represented primary consumers with trophic levels ranging from 2.0 to 2.7. Secondary consumers included two macroinvertebrates and seven fishes with trophic levels varying between 3.0 and 3.9. The consumers were divided into three trophic guilds, i.e., detritivorous/algae feeders, omnivores and carnivores. The detrital food chain was the main energy flow pathway in the salt marsh food web of the Changjiang River Estuary, and the marsh vascular plants were at least as equally important as microphytobenthos for secondary production. The important trophic function of the salt marsh habitats in the estuary is revealed.

  15. Evaluation of a 15N plot design for estimating plant recovery of fertilizer nitrogen applied to sugar cane

    OpenAIRE

    1994-01-01

    Two experiments were conducted on commercial sugar cane fields cropped with the variety SP70-1143, with the objective of evaluating a single row microplot design to determine plant recovery of 15N fertilizer nitrogen. One of them used 15N-aqua ammonia and 15N-urea applied to two linear meter microplots of a ratoon crop (four replicates). The second used one linear meter microplots (three replicates) which received 15N-aqua ammonia only. The fertilizers were applied on 15cm deep furrows, locat...

  16. \\Delta Y/ \\Delta Z from the analysis of local K dwarfs

    CERN Document Server

    Gennaro, Mario; Degl'Innocenti, Scilla

    2010-01-01

    The stellar helium-to-metal enrichment ratio, \\Delta Y/\\Delta Z, is a widely studied astrophysical quantity. However, its value is still not precisely constrained. This paper is focused on the study of the main sources of uncertainty which affect the \\Delta Y/\\Delta Z derived from the analysis of the low-main sequence (MS) stars in the solar neighborhood. The possibility to infer the value of \\Delta Y/\\Delta Z from the study of low-MS stars relies on the dependence of the stellar luminosity and effective temperature on the initial Y and Z. The \\Delta Y/\\Delta Z ratio is obtained by comparing the magnitude difference between the observed stars and a reference theoretical zero age main sequence (ZAMS) with the related theoretical magnitude differences computed from a new set of stellar models with up-to-date input physics and a fine grid of chemical compositions. A Monte Carlo approach has been used to evaluate the impact on the result of different sources of uncertainty, i.e. observational errors, evolutionary...

  17. A novel method for trapping and analyzing 15N in NO for tracing NO sources

    Science.gov (United States)

    Kang, Ronghua; Mulder, Jan; Dörsch, Peter

    2016-04-01

    15N isotope tracing is an effective and direct approach to investigate the biological and chemical sources of nitric oxide (NO) in soil. However, NO is highly reactive and rapidly converted to nitrogen dioxide (NO2) in the presence of ozone. Various chemical conversions of NO to the more stable solutes nitrite (NO2-) and nitrate (NO3-) have been proposed, which allow analysing the 15N abundance without major fractionation. However, NO emissions from soils are usually small, posing major challenges to conversion efficiency and background contamination. Here we present a novel method in which NO is oxidized to NO2- by chromium trioxide (CrO3) prior to conversion to NO2- and NO3- in an alkaline hydrogen peroxide (H2O2) solution. Immediately following trapping, manganese dioxide (MnO2) and 5M HCl are added to remove excess H2O2, and to adjust the pH to around 6.0-7.0, respectively. The resulting solution can be stored until analysis and is none-toxic, allowing to use a modified denitrifier method (Zhu et al., submitted), where NO2- and NO3- are reduced quantitatively to nitrous oxide (N2O). Optimum NO conversion rates of > 90% even at extremely low initial NO concentration were obtained with 4% H2O2, 0.5 M NaOH, and 0.5 L min-1 gas flow rate. In a laboratory test, using NO gas with different 15N signals produced from unlabelled and labelled NO2-, we found an overall precision of 0.4‰ for unlabelled and 49.7‰ for NO enriched with 1.0 atom% 15N, respectively. This indicates that this method can be used for both natural abundance studies of NO, as well as in labelling studies tracing NO sources. Zhu J, Yu L, Bakken LR, Mørkved PT, Mulder J, Dörsch P. Controlled induction of denitrification in Pseudomonas aureofaciens: a modified denitrifier method for 15N and 18O analysis in NO3- from natural water samples by IRMS. Submitted.

  18. The Influence of Seed-borne N in 15N Isotope Dilution Studies with Legumes The Influence of Seed-borne N in 15N Isotope Dilution Studies with Legumes

    DEFF Research Database (Denmark)

    Jensen, Erik Steen; Andersen, A. J.; Thomsen, J. D.

    1985-01-01

    The distriution of seed-borne N in shoot and root of pea and field bean was studied using three methods: 1) determination of the N content in shoot and root of plants grown in sand culture without other N sources. 2) 15N isotope dilution in plants grown in Rhizobium-free medium supplied with 15N...

  19. Multiple regression models of δ13C and δ15N for fish populations in the eastern Gulf of Mexico

    Science.gov (United States)

    Radabaugh, Kara R.; Peebles, Ernst B.

    2014-08-01

    Multiple regression models were created to explain spatial and temporal variation in the δ13C and δ15N values of fish populations on the West Florida Shelf (eastern Gulf of Mexico, USA). Extensive trawl surveys from three time periods were used to acquire muscle samples from seven groundfish species. Isotopic variation (δ13Cvar and δ15Nvar) was calculated as the deviation from the isotopic mean of each fish species. Static spatial data and dynamic water quality parameters were used to create models predicting δ13Cvar and δ15Nvar in three fish species that were caught in the summers of 2009 and 2010. Additional data sets were then used to determine the accuracy of the models for predicting isotopic variation (1) in a different time period (fall 2010) and (2) among four entirely different fish species that were collected during summer 2009. The δ15Nvar model was relatively stable and could be applied to different time periods and species with similar accuracy (mean absolute errors 0.31-0.33‰). The δ13Cvar model had a lower predictive capability and mean absolute errors ranged from 0.42 to 0.48‰. δ15N trends are likely linked to gradients in nitrogen fixation and Mississippi River influence on the West Florida Shelf, while δ13C trends may be linked to changes in algal species, photosynthetic fractionation, and abundance of benthic vs. planktonic basal resources. These models of isotopic variability may be useful for future stable isotope investigations of trophic level, basal resource use, and animal migration on the West Florida Shelf.

  20. Delta hedging strategies comparison

    DEFF Research Database (Denmark)

    De Giovanni, Domenico; Ortobelli, S.; Rachev, S.T.

    2008-01-01

    In this paper we implement dynamic delta hedging strategies based on several option pricing models. We analyze different subordinated option pricing models and we examine delta hedging costs using ex-post daily prices of S&P 500. Furthermore, we compare the performance of each subordinated model ...

  1. Long-term 15N tracking from biological N fixation across different plant and humus components of the boreal forest

    Science.gov (United States)

    Arroniz-Crespo, Maria; Jones, David L.; Zackrisson, Olle; Nilsson, Marie-Charlotte; DeLuca, Thomas H.

    2014-05-01

    Biological N2 fixation by cyanobacteria associated with feather mosses is an important cog in the nitrogen (N) cycle of boreal forests; still, our understanding of the turnover and fate of N fixed by this association remains greatly incomplete. The 15N signature of plants and soil serves as a powerful tool to explore N dynamics in forest ecosystems. In particular, in the present study we aimed to investigate the contribution of N2 fixation to δ15N signatures of plants and humus component of the boreal forest. Here we present results from a long-term (7 years) tacking of labelled 15N2 across the humus layer, seedlings of the tree species Pinus sylvestris, two common dwarf shrub species (Empetrum hermaphroditum and Vaccinium vitis-idaea) and the feather moss Pleurozium schreibery. The enriched experiment was conducted in 2005 in a natural boreal forest in northern Sweden. Two different treatments (10% 15N2 headspace enrichment and control) were setup in nine different plots (0.5 x 0.5 m) within the forest. We observed a significant reduction of δ15N signature of the 15N-enriched moss that could be explained by a growth dilution effect. Nevertheless, after 5 years since 15N2 enrichment some of the label 15N was still detected on the moss and in particular in the dead tissue. We could not detect a clear transfer of the labelled 15N2 from the moss-cyanobacteria system to other components of the ecosystem. However, we found consistence relationship through time between increments of δ15N signature of some of the forest components in plots which exhibited higher N fixation rates in the moss. In particular, changes in natural abundance δ15N that could be associated with N fixation were more apparent in the humus layer, the dwarf shrub Vaccinium vitis-idaea and the pine seedlings when comparing across plots and years.

  2. MODIFICATION OF DELTA FOR CHOOSER OPTIONS

    Directory of Open Access Journals (Sweden)

    Marek Ďurica

    2015-09-01

    Full Text Available Correctly used financial derivatives can help investors increase their expected returns and minimize their exposure to risk. To ensure the specific needs of investors, a large number of different types of non-standard exotic options is used. Chooser option is one of them. It is an option that gives its holder the right to choose at some predetermined future time whether the option will be a standard call or put with predetermined strike price and maturity time. Although the chooser options are more expensive than standard European-style options, in many cases they are a more suitable instrument for investors in hedging their portfolio value. For an effective use of the chooser option as a hedging instrument, it is necessary to check the values of the Greek parameters delta and gamma for the options. Especially, if the value of the parameter gamma is too large, hedging of the portfolio value using only parameter delta is insufficient and brings high transaction costs because the portfolio has to be reviewed relatively often. Therefore, in this article, a modification of delta-hedging as well as using the value of parameter gamma is suggested. Error of the delta modification is analyzed and compared with the error of widely used parameter delta. Typical patterns for the modified hedging parameter variation with various time to choose time for chooser options are also presented in this article.

  3. Thousand Year Archives of the Bulk and Compound-Specific δ15N of Export Production From the North Pacific Subtropical Gyre Indicate Increasing Nitrogen Fixation Over the Past 150 Years

    Science.gov (United States)

    Sherwood, O.; Batista, F. C.; Brown, J. T.; Guilderson, T. P.; McCarthy, M.

    2012-12-01

    Stable nitrogen isotopic analysis of amino acids (δ15N-AA) preserved in proteins has emerged as a powerful new tool to explore trophic levels and nutrient cycling in nature. To date, little has been done to explore δ15N-AA in paleo-studies of the marine nitrogen cycle. We analysed the bulk and AA-specific δ15N in the long-lived, deep-sea, proteinaceous coral Gerardia. By feeding on sinking particulate organic matter, proteinaceous corals integrate the biogeochemical signature of recently exported production within discrete skeletal growth layers. Sub-decadal resolution time-series records spanning the time period 1000 AD to present were generated from specimens of Gerardia collected from the main Hawaiian Islands, Cross Seamount, and French Frigate Shoals in the North Pacific Subtropical Gyre (NPSG). Records of bulk δ15N from the three different locations, geographically separated by up to 1000 km, showed remarkably similar long term trends. Bulk δ15N remained relatively stable from ~1000-1850 years AD, and then decreased by a total of 2 ‰ from ~1850 AD to the present. The δ15N-AA of the "trophic" group of amino acids indicated no significant changes in trophic level or microbial re-synthesis of export production over this time period. The δ15N of "source" amino acids was significantly correlated with corresponding values of bulk δ15N, with the δ15N of phenylalanine decreasing from 4.2 to 2.1‰. The latter value is similar to recent measurements of subsurface nitrate δ15N near Hawaii, suggesting that the δ15N of phenylalanine may be used to quantitatively track changes in the isotopic signature of nitrate at the base of the food web. Using a simple isotopic mass balance between upwelled nitrate and nitrogen fixation we calculate a 30% increase in nitrogen fixation in the NPSG since ~1850. These results provide invaluable long-term context for recent observations, and highlight profound changes in the marine biogeochemical cycling of nitrogen over the

  4. Simple and accurate determination of global tau(R) in proteins using (13)C or (15)N relaxation data.

    Science.gov (United States)

    Mispelter, J; Izadi-Pruneyre, N; Quiniou, E; Adjadj, E

    2000-03-01

    In the study of protein dynamics by (13)C or (15)N relaxation measurements different models from the Lipari-Szabo formalism are used in order to determine the motion parameters. The global rotational correlation time tau(R) of the molecule must be estimated prior to the analysis. In this Communication, the authors propose a new approach in determining an accurate value for tau(R) in order to realize the best fit of R(2) for the whole sequence of the protein, regardless of the different type of motions atoms may experience. The method first determines the highly structured regions of the sequence. For each corresponding site, the Lipari-Szabo parameters are calculated for R(1) and NOE, using an arbitrary value for tau(R). The chi(2) for R(2), summed over the selected sites, shows a clear minimum, as a function of tau(R). This minimum is used to better estimate a proper value for tau(R).

  5. Intestinal renal metabolism of L-citrulline and L-arginine following enteral or parenteral infusion of L-alanyl-L-[2,15N]glutamine or L-[2,15N]glutamine in mice.

    Science.gov (United States)

    Boelens, Petra G; van Leeuwen, Paul A M; Dejong, Cornelis H C; Deutz, Nicolaas E P

    2005-10-01

    Previously, we observed increased plasma arginine (ARG) concentrations after glutamine (GLN)-enriched diets, in combination with clinical benefits. GLN delivers nitrogen for ARG synthesis, and the present study was designed to quantify the interorgan relationship of exogenous L-GLN or GLN dipeptide, by enteral or parenteral route, contributing to intestinal citrulline (CIT) and renal de novo ARG synthesis in mice. To study this, we used a multicatheterized mouse model with Swiss mice (n = 43) in the postabsorptive state. Stable isotopes were infused into the jugular vein or into the duodenum {per group either free L-[2,(15)N]GLN or dipeptide L-ALA-L-[2,(15)N]GLN, all with L-[ureido-(13)C-(2)H(2)]CIT and L-[guanidino-(15)N(2)-(2)H(2)]ARG} to establish renal and intestinal ARG and CIT metabolism. Blood flow was measured using (14)C-para-aminohippuric acid. Net intestinal CIT release, renal uptake of CIT, and net renal ARG efflux was found, as assessed by arteriovenous flux measurements. Quantitatively, more de novo L-[2,(15)N]CIT was produced when free L-[2,(15)N]GLN was given than when L-ALA-L-[2,(15)N]GLN was given, whereas renal de novo L-[2,(15)N]ARG was similar in all groups. In conclusion, the intestinal-renal axis is hereby proven in mice in that L-[2,(15)N]GLN or dipeptide were both converted into de novo renal L-[2,(15)N]ARG; however, not all was derived from intestinal L-[2,(15)N]CIT production. In this model, the feeding route and form of GLN did not influence de novo renal ARG production derived from GLN.

  6. Horizontal Symmetries $\\Delta(150)$ and $\\Delta(600)$

    CERN Document Server

    Lam, C S

    2013-01-01

    Using group theory of mixing to examine all finite subgroups of SU(3) with an order less than 512, we found recently that only the group $\\Delta(150)$ can give rise to a correct reactor angle $\\th_{13}$ of neutrino mixing without any free parameter. It predicts $\\sin^22\\th_{13}=0.11$ and a sub-maximal atmospheric angle with $\\sin^22\\th_{23}=0.94$, in good agreement with experiment. The solar angle $\\th_{12}$, the CP phase $\\d$, and the neutrino masses $m_i$ are left as free parameters. In this article we provide more details of this case, discuss possible gain and loss by introducing right-handed symmetries, and/or valons to construct dynamical models. A simple model is discussed where the solar angle agrees with experiment, and all its mixing parameters can be obtained from the group $\\Delta(600)$ by symmetry alone. The promotion of $\\Delta(150)$ to $\\Delta(600)$ is on the one hand analogous to the promotion of $S_3$ to $S_4$ in the presence of tribimaximal mixing, and on the other hand similar to the extens...

  7. Localization of 15N uptake in a Tibetan alpine Kobresia pasture

    Science.gov (United States)

    Schleuß, Per-Marten; Kuzyakov, Yakov

    2014-05-01

    The Kobresia Pygmea ecotone covers approximately 450.000 km2 and is of large global and regional importance due several socio-ecological aspects. For instance Kobresia pastures store high amounts of carbon, nitrogen and other nutrients, represent large grazing areas for herbivores, provide a fast regrowth after grazing events and protect against mechanical degradation and soil erosion. However, Kobresia pastures are assumed to be a grazing induced and are accompanied with distinct root mats varying in thickness between 5-30 cm. Yet, less is known about the morphology and the functions of this root mats, especially in the background of a progressing degradation due to changes of climate and management. Thus we aimed to identify the importance of single soil layers for plant nutrition. Accordingly, nitrogen uptake from different soil depths and its remain in above-ground biomass (AGB), belowground biomass (BGB) and soil were determined by using a 15N pulse labeling approach during the vegetation period in summer 2012. 15N urea was injected into six different soil depths (0.5 cm, 2.5 cm, 7.5 cm, 12.5 cm, 17.5 cm, 22.5 cm / for each 4 replicates) and plots were sampled 45 days after the labeling. For soil and BGB samples were taken in strict sample intervals of 0-1 cm, 1-5 cm, 5-10 cm, 10-15 cm, 15-20 cm, 20-25 cm. Results indicate that total recovery (including AGB, BGB and soil) was highest, if tracer was injected into the top 5 cm and subsequently decreased with decreasing injection depth. This is especially the case for the 15N recovery of BGB, which is clearly attributed to the root density and strongly decreased with soil depth. In contrast, the root activity derived from the 15N content of roots increased with soil depth, which is primary associated to a proportionate increase of living roots related to dead roots. However, most 15N was captured in plant biomass (67.5-85.3 % of total recovery), indicating high 15N uptake efficiency possibly due to N limitation

  8. Growth and foliar d15N of a Mojave desert shrub in relation to soil hydrological dynamics

    Science.gov (United States)

    Foliar 15N ratios (del15N), % N, and canopy volumes were measured in the two Mojave Desert dominant shrubs, the evergreen Larrea tridentata and drought deciduous Ambrosia dumosa growing across a geomorphically determined soil mosaic. Across three soils with increasingly strong age-dependent surface...

  9. Optimizing Industrial Value Chain in Yangtze River Delta based on B2B Platform%基于B2B平台的长三角产业价值链升级研究

    Institute of Scientific and Technical Information of China (English)

    刘辉

    2013-01-01

    根据价值链和电子商务理论与实践可以发现, B2B电子商务平台正在改变产业价值链模式,为提升产业价值链带来新的战略途径。长三角内外产业价值链的正在经历跨边界重组,较为发达的B2B平台环境则提供了重要的技术条件。以阿里巴巴为例分析来看, B2B平台中存在着国内和国外两类产业价值链的复杂嵌套,而国内企业在全球价值链中还基本处在低端位置。 B2B电子商务平台支持的产业价值链租金是长三角价值链高级化的基本动力之一;长三角未来应有意识地引导充分利用中心城市的比较聚集优势,政府通过宏观协调,形成发挥B2B平台优势的产业环境,通过B2B电子商务平台激活高级要素,采取全球产业价值链与国内产业价值链并建的策略。%According to value chain and e-commerce theories and practice, it is found that the B2B platform is changing the industrial value chain model, and innovating the strategy to enhance the value chain of the industry. While the boom of B2B plat-form in Yangtze River Delta is creating new industrial environment, the industrial value chain is witnessing an unprecedented cross boundary recombination. Take the well-known Alibaba B2B as example, which enjoys more than 60% market share in Chi-na, it is found that both domestic and global industrial value chain exists and even nested on the platform. Further observations re-vealed that domestic enterprises in the global value chain are still in the low-end position. In order to solve this problem , B2B platforms could make play a unique role to upgrade the two value chain. Local government should make full use of regional center cities through the macroeconomic coordination, enjoying as much spillover effects as possible from the B2B platform.

  10. Capture cross sections of 15N(n, γ)16N at astrophysical energies

    Science.gov (United States)

    Fan, Guang-Wei; Ma, Jun-Bing; Sheng, Zong-Qiang; Shi, Guo-Zhu; Tian, Feng; Wang, Jun; Zhang, Chao

    2016-12-01

    We have reanalyzed reaction cross sections of 16N on a 12C target. The nucleon density distribution of 16N, especially surface density distribution, was extracted using the modified Glauber model. On the basis of dilute surface densities, the 15N(n, γ)16N reaction is discussed within the framework of the direct capture reaction mechanism. The calculations agree quite well with the experimental data. Support given by National Natural Science Foundation of China (11447236, 11505002, 11247001) and Foundation of Anhui University of Science and Technology (11130, 12608)

  11. Uptake of stormwater nitrogen in bioretention systems demonstrated from 15N tracer techniques

    Science.gov (United States)

    Houdeshel, D.; Hultine, K. R.; Pomeroy, C. A.

    2012-12-01

    Bioretention stormwater management systems are engineered ecosystems that capture urban stormwater in order to reduce the harmful effects of stormwater pollution on receiving waters. Bioretention systems have been shown to be effective at reducing the volume of runoff, and thereby reduce the nutrient loading to receiving waters from urban areas. However, little work has been done to evaluate the treatment processes that are responsible for reductions in effluent nitrogen (N). We hypothesize that the pulses of inorganic nitrogen associated with urban runoff events are captured in the plat tissues within these systems and not adsorbed to the soil media, thus creating a long-term, sustainable treatment approach to reducing the total nutrient loading to receiving waters. Nitrogen treatment performance was tested on two bioretention systems in Salt Lake City, UT: 1) an upland native community that does not require irrigation in semi-arid climates, and 2) a wetland community that requires 250 l of daily irrigation to offset the relatively high evaporative demand in the region. Each cell is sized to treat a 2.5 cm storm from a 140 m2 impervious surface: the area of the bioretention system is 10 m2. To test the N removal performance of each system, runoff events were simulated to represent an average precipitation regime using a synthetic stormwater blend starting in January, 2012. Effluent was collected from an underdrain and analyzed for total nitrogen (TN); mass removal was calculated for each month by subtracting the TN mass added to the garden minus the TN mass that flowed out of the garden. To test the hypothesis that plants assimilate stormwater N, 4 g of 100 atom% 15N NH4NO3 tracer was used as the N source in the synthetic stormwater during the first 2,000 l synthetic storm event in May. This isotopic label was calculated to enrich the total N pool of each garden to 100‰ 15N/14Nair. New growth was harvested from each plant in both cells and analyzed for 15N

  12. Optical Microscopy Characterization for Borehole U-15n#12 in Support of NCNS Source Physics Experiment

    Energy Technology Data Exchange (ETDEWEB)

    Wilson, Jennifer E. [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Sussman, Aviva Joy [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

    2015-05-22

    Optical microscopy characterization of thin sections from corehole U-15n#12 is part of a larger material characterization effort for the Source Physics Experiment (SPE). The SPE program was conducted in Nevada with a series of explosive tests designed to study the generation and propagation of seismic waves inside Stock quartz monzonite. Optical microscopy analysis includes the following: 1) imaging of full thin sections (scans and mosaic maps); 2) high magnification imaging of petrographic texture (grain size, foliations, fractures, etc.); and 3) measurement of microfracture density.

  13. Effect of estrogens on urinary /sup 15/N balance in girls

    Energy Technology Data Exchange (ETDEWEB)

    Zachmann, M.; Kempken, B.; Prader, A. (Zurich Univ. (Switzerland))

    1984-08-01

    While the anabolic and growth-promoting effects of testosterone are known to be important for pubertal growth in boys, the role of estrogens (E) in the female spurt is less certain. Adrenal androgens have been considered to be more important than ovarian E. To study the anabolic effects of E, there has been carried out a pilot study in 9 girls aged 11 to 15 years. Before and 6 days after the start of E treatment, urinary /sup 15/N balance studies were performed, using /sup 15/NH/sub 4/Cl.

  14. (13)C and (15)N solid-state NMR studies on albendazole and cyclodextrin albendazole complexes.

    Science.gov (United States)

    Ferreira, M João G; García, A; Leonardi, D; Salomon, Claudio J; Lamas, M Celina; Nunes, Teresa G

    2015-06-05

    (13)C and (15)N solid-state nuclear magnetic resonance (NMR) spectra were recorded from albendazole (ABZ) and from ABZ:β-cyclodextrin, ABZ:methyl-β-cyclodextrin, ABZ:hydroxypropyl-β-cyclodextrin and ABZ:citrate-β-cyclodextrin, which were prepared by the spray-drying technique. ABZ signals were typical of a crystalline solid for the pure drug and of an amorphous compound obtained from ABZ:cyclodextrin samples. Relevant spectral differences were correlated with chemical interaction between ABZ and cyclodextrins. The number and type of complexes revealed a strong dependence on the cyclodextrin group substituent. Solid-state NMR data were consistent with the presence of stable inclusion complexes.

  15. Sinks for nitrogen inputs in terrestrial ecosystems: a meta-analysis of 15N tracer field studies

    Science.gov (United States)

    Templer, P.H.; Mack, M.C.; Chapin, F. S.; Christenson, L.M.; Compton, J.E.; Crook, H.D.; Currie, W.S.; Curtis, C.J.; Dail, D.B.; D'Antonio, C. M.; Emmett, B.A.; Epstein, H.E.; Goodale, C.L.; Gundersen, P.; Hobbie, S.E.; Holland, K.; Hooper, D.U.; Hungate, B.A.; Lamontagne, S.; Nadelhoffer, K.J.; Osenberg, C.W.; Perakis, S.S.; Schleppi, P.; Schimel, J.; Schmidt, I.K.; Sommerkorn, M.; Spoelstra, J.; Tietema, A.; Wessel, W.W.; Zak, D.R.

    2012-01-01

    Effects of anthropogenic nitrogen (N) deposition and the ability of terrestrial ecosystems to store carbon (C) depend in part on the amount of N retained in the system and its partitioning among plant and soil pools. We conducted a meta-analysis of studies at 48 sites across four continents that used enriched 15N isotope tracers in order to synthesize information about total ecosystem N retention (i.e., total ecosystem 15N recovery in plant and soil pools) across natural systems and N partitioning among ecosystem pools. The greatest recoveries of ecosystem 15N tracer occurred in shrublands (mean, 89.5%) and wetlands (84.8%) followed by forests (74.9%) and grasslands (51.8%). In the short term (15N tracer application), total ecosystem 15N recovery was negatively correlated with fine-root and soil 15N natural abundance, and organic soil C and N concentration but was positively correlated with mean annual temperature and mineral soil C:N. In the longer term (3–18 months after 15N tracer application), total ecosystem 15N retention was negatively correlated with foliar natural-abundance 15N but was positively correlated with mineral soil C and N concentration and C: N, showing that plant and soil natural-abundance 15N and soil C:N are good indicators of total ecosystem N retention. Foliar N concentration was not significantly related to ecosystem 15N tracer recovery, suggesting that plant N status is not a good predictor of total ecosystem N retention. Because the largest ecosystem sinks for 15N tracer were below ground in forests, shrublands, and grasslands, we conclude that growth enhancement and potential for increased C storage in aboveground biomass from atmospheric N deposition is likely to be modest in these ecosystems. Total ecosystem 15N recovery decreased with N fertilization, with an apparent threshold fertilization rate of 46 kg N·ha-1·yr-1 above which most ecosystems showed net losses of applied 15N tracer in response to N fertilizer addition.

  16. Rapid, storm-induced changes in the natural abundance of 15N in a planktonic ecosystem, Chesapeake Bay, USA

    Science.gov (United States)

    Montoya, J. P.; Korrigan, S. G.; McCarthy, J. J.

    1991-12-01

    Samples of dissolved inorganic nitrogen (DIN), particulate nitrogen (PN) and two species of Zooplankton were collected during two north-south transects of the Chesapeake Bay in the autumn of 1984 (27-28 September and 3-5 October). During the first transect, the natural abundance of 15N ( δ15N) in the major dissolved and planktonic pools of nitrogen suggested that the δ15N of PN was largely determined by isotopic fractionation during uptake of NH 4+ by phytoplankton. Averaged over the transect as a whole, the δ15N of the herbivorous calanoid copepod Acartia tonsa was 4.1‰ higher than that of the PN, while the δ15N of the carnivorous ctenophore Mnemiopsis leidyi was 6.4‰ higher than that of the PN. In the interval between the two transects, storm-induced mixing of the water column resulted in the injection of NH 4+ into the surface layer of the bay. This perturbation in the estuarine nitrogen cycle resulted in marked changes in the δ15N of the major dissolved and planktonic pools of nitrogen in the bay. In combination with ancillary physical, chemical and biological data, these changes in δ15N provided estimates of the isotopic fractionation factor for NH 4+ uptake by phytoplankton ( α = 1.0065 -1.0080) as well as the turnover time of nitrogen in Acartia tonsa (6.0-9.6 days). Despite the changes in δ15N observed during this cruise, the relative distribution of 15N between trophic levels was preserved: during the second transect, the difference in δ15N between Acartia tonsa and PN was 3.6‰ and the difference in δ15N between Mnemiopsis leidyi and PN was 7.3‰. These results demonstrate that the natural abundance of 15N can change dramatically on a time scale of days and that time-series studies of the natural abundance of 15N can be a useful complement to studies using tracer additions of 15N to document nitrogen transformations in planktonic ecosystems.

  17. A δ(15)N assessment of nitrogen deposition for the endangered epiphytic orchid Laelia speciosa from a city and an oak forest in Mexico.

    Science.gov (United States)

    Díaz-Álvarez, Edison A; Reyes-García, Casandra; de la Barrera, Erick

    2016-09-01

    Atmospheric nitrogen deposition poses a major threat to global biodiversity. Tropical epiphytic plants are especially at risk given their reliance on atmospheric sources of nutrients. The leaf, pseudobulb, and root carbon and nitrogen content, C:N ratio, as well as the nitrogen isotopic composition were studied for individuals of Laelia speciosa from a city and from an oak forest in Mexico. The nitrogen content of leaves was similar between the city and the oak forest, reaching 1.3 ± 0.2 % (dry mass). The δ(15)N of leaves, pseudobulbs, and roots reached 5.6 ± 0.2 ‰ in the city, values found in sites exposed to industrial and vehicular activities. The δ(15)N for plant from the oak forest amounted to -3.1 ± 0.3 ‰, which is similar to values measured from sites with low industrial activities. Some orchids such as Laelia speciosa produce a single pseudobulb per year, i.e., a water and nutrient storage organ, so the interannual nitrogen deposition was studied by considering the ten most recent pseudobulbs for plants from either site formed between 2003 and 2012. The C:N ratio of the ten most recent pseudobulbs from the oak forest, as well as that of the pseudobulbs formed before 2010 for plants in the city were indistinguishable from each other, averaging 132.4 ± 6.5, while it was lower for the two most recent pseudobulbs in the city. The δ(15)N values of pseudobulbs from the oak forest averaged ‒4.4 ± 0.1 ‰ for the entire series. The δ(15)N ranged from 0.1 ± 1.6 ‰ for the oldest pseudobulb to 4.7 ± 0.2 ‰ for the pseudobulb formed in the city from 2008 onwards. Isotopic analysis and the C:N ratio for L. speciosa revealed that rates of nitrogen deposition were higher in the city than in the forest. The δ(15)N values of series of pseudobulbs showed that it is possible to track nitrogen deposition over multiple years.

  18. Enrichment of natural (15)N abundance during soil N losses under 20years of continuous cereal cropping.

    Science.gov (United States)

    Jones, Andrew R; Dalal, Ram C

    2017-01-01

    It is generally accepted that the enrichment of natural (15)N abundance in soil over time is reflective of historic N cycling and loss, but this process in cropping soils is not yet clear. In this study, we identified an enrichment gradient of natural (15)N abundance during 20-year chronosequence of cereal cropping on Alfisols in southwest Queensland, Australia, that have no history of fertilisation. We demonstrate that the increase in soil (15)N abundance is explained by isotopic fractionation of (15)N during organic N mineralisation and nitrification, which lead to isotopically heavier ammonium retained in the soil and isotopically lighter soil nitrate taken up and removed by seasonal crops during harvest. Here we present a framework for natural (15)N isotopic fractionation co-occurring with N losses during long-term cultivation.

  19. A 15N-poor isotopic composition for the solar system as shown by Genesis solar wind samples.

    Science.gov (United States)

    Marty, B; Chaussidon, M; Wiens, R C; Jurewicz, A J G; Burnett, D S

    2011-06-24

    The Genesis mission sampled solar wind ions to document the elemental and isotopic compositions of the Sun and, by inference, of the protosolar nebula. Nitrogen was a key target element because the extent and origin of its isotopic variations in solar system materials remain unknown. Isotopic analysis of a Genesis Solar Wind Concentrator target material shows that implanted solar wind nitrogen has a (15)N/(14)N ratio of 2.18 ± 0.02 × 10(-3) (that is, ≈40% poorer in (15)N relative to terrestrial atmosphere). The (15)N/(14)N ratio of the protosolar nebula was 2.27 ± 0.03 × 10(-3), which is the lowest (15)N/(14)N ratio known for solar system objects. This result demonstrates the extreme nitrogen isotopic heterogeneity of the nascent solar system and accounts for the (15)N-depleted components observed in solar system reservoirs.

  20. Rapid mass spectrometric analysis of 15N-Leu incorporation fidelity during preparation of specifically labeled NMR samples

    DEFF Research Database (Denmark)

    Truhlar, Stephanie M E; Cervantes, Carla F; Torpey, Justin W

    2008-01-01

    Advances in NMR spectroscopy have enabled the study of larger proteins that typically have significant overlap in their spectra. Specific (15)N-amino acid incorporation is a powerful tool for reducing spectral overlap and attaining reliable sequential assignments. However, scrambling of the label...... during protein expression is a common problem. We describe a rapid method to evaluate the fidelity of specific (15)N-amino acid incorporation. The selectively labeled protein is proteolyzed, and the resulting peptides are analyzed using MALDI mass spectrometry. The (15)N incorporation is determined...... by analyzing the isotopic abundance of the peptides in the mass spectra using the program DEX. This analysis determined that expression with a 10-fold excess of unlabeled amino acids relative to the (15)N-amino acid prevents the scrambling of the (15)N label that is observed when equimolar amounts are used...

  1. Spectroscopic observations of 14N/15N ratios in both NH2 and CN in comet C/2013 US10 (Catalina)

    Science.gov (United States)

    Shinnaka, Yoshiharu; Kawakita, Hideyo

    2016-10-01

    Comet is one of the primordial small bodies in the solar system and probably it has kept the information about the evolution of materials from the pre-solar molecular cloud to the solar nebula.Isotopic ratio in volatiles is one of the primordial properties of comets. A heavier isotopes trend to be captured into a molecule by chemical reactions under very low-temperature conditions (called as fractionation). For instance, D/H ratio of water (HDO/H2O) in comet is enriched in D atom than the elemental abundance ratios of D/H in entire solar system [1]. Based on the observed D/H ratios in cometary water, a presumed temperature is ~20-50 K as the formation temperature of water (most abundant volatiles in cometary nucleus), by assuming water formed in gas-phase chemistry [2].Besides, the nitrogen isotopic ratios (14N/15N) have been determined from CN and HCN (which is believed a dominant "parent" species of CN in the coma) in >20 comets [3,4]. They demonstrated cometary HCN and CN show high 15N-fractionation with respect to the proto-solar value by a factor of ~3 and with a small diversity. Moreover, 14N/15N ratios in NH3 in comets has been determined from intensity ratios of NH2 isotopologues [5,6,7], and both 15N-fractionation as much as HCN in comets and a small diversity are seen in those 14N/15N ratios in NH3. However, there is a few reports about 14N/15N ratios in both HCN and NH3 in the same comets, and discussions about the relationship between these 14N/15N ratios have not been yet.We present 14N/15N ratios in both NH2 and CN in comet C/2013 US10 (Catalina). High-resolution optical spectra of the comet were taken with the HDS spectrograph mounted on the Subaru Telescope (Hawaii) on UT 2016 January 2-3. We will discuss about the origins of these volatiles based on the 14N/15N ratios.This work was supported by Graint-in-Aid for JSPS Fellows, 15J10864 (YS).References:[1] Lis et al., 2013, ApJ 774, L3[2] Millar et al., 1989, ApJ 340, 906[3] Bockelée-Morvan et al

  2. UV-visible and (1)H-(15)N NMR spectroscopic studies of colorimetric thiosemicarbazide anion sensors.

    Science.gov (United States)

    Farrugia, Kristina N; Makuc, Damjan; Podborska, Agnieszka; Szaciłowski, Konrad; Plavec, Janez; Magri, David C

    2015-02-14

    Four model thiosemicarbazide anion chemosensors containing three N-H bonds, substituted with phenyl and/or 4-nitrophenyl units, were synthesised and studied for their anion binding abilities with hydroxide, fluoride, acetate, dihydrogen phosphate and chloride. The anion binding properties were studied in DMSO and 9 : 1 DMSO-H2O by UV-visible absorption and (1)H/(13)C/(15)N NMR spectroscopic techniques and corroborated with DFT studies. Significant changes were observed in the UV-visible absorption spectra with all anions, except for chloride, accompanied by dramatic colour changes visible to the naked eye. These changes were determined to be due to the deprotonation of the central N-H proton and not due to hydrogen bonding based on (1)H/(15)N NMR titration studies with acetate in DMSO-d6-0.5% water. Direct evidence for deprotonation was confirmed by the disappearance of the central thiourea proton and the formation of acetic acid. DFT and charge distribution calculations suggest that for all four compounds the central N-H proton is the most acidic. Hence, the anion chemosensors operate by a deprotonation mechanism of the central N-H proton rather than by hydrogen bonding as is often reported.

  3. Stereospecific assignments of glycine in proteins by stereospecific deuteration and {sup 15}N labeling

    Energy Technology Data Exchange (ETDEWEB)

    Hansen, A.P.; Curley, R.W. Jr.; Panigot, M.J.; Fesik, S.W. [Ohio State Univ., Columbus, OH (United States)

    1994-12-01

    Stereospecific assignments are important for accurately determining the three-dimensional structures of proteins through the use of multidimensional NMR techniques. It is especially important to stereospecifically assign the glycine {alpha}-protons in proteins because of the potential for different backbone conformations of this residue. These stereospecific assignments are critical for interpreting the {sup 3}J{sub NH,{alpha}H} coupling constants and NOEs involving the glycine {alpha}-protons that determine the conformation of this part of the protein. However, it is often difficult to unambiguously obtain the stereospecific assignments for glycine residues by using only NOE data. In this poster, we present a method for unambiguous, stereospecific assignment of the {alpha}-protons of glycine residues. This method involves synthesis of stereo-specifically deuterated and {sup 15}N-labeled Gly using a slightly modified procedure originally described by Woodard and coworkers for the stereoselective deuteration of glycine. The stereospecifically deuterated and {sup 15}N-labeled Gy has been incorporated into recombinant proteins expressed in both bacterial systems (FKBP) and mammalian cells (u-PA). Two- and three-dimensional isotope-filtered and isotope-edited NMR experiments were used to obtain the stereospecific assignments of the glycine {alpha}-protons for these proteins.

  4. The Origin of Nitrogen on Jupiter and Saturn from the $^{15}$N/$^{14}$N Ratio

    CERN Document Server

    Fletcher, Leigh N; Orton, Glenn S; Irwin, Patrick G J; Mousis, Olivier; Sinclair, James A; Giles, Rohini S

    2014-01-01

    The Texas Echelon cross Echelle Spectrograph (TEXES), mounted on NASA's Infrared Telescope Facility (IRTF), was used to map mid-infrared ammonia absorption features on both Jupiter and Saturn in February 2013. Ammonia is the principle reservoir of nitrogen on the giant planets, and the ratio of isotopologues ($^{15}$N/$^{14}$N) can reveal insights into the molecular carrier (e.g., as N$_2$ or NH$_3$) of nitrogen to the forming protoplanets, and hence the source reservoirs from which these worlds accreted. We targeted two spectral intervals (900 and 960 cm$^{-1}$) that were relatively clear of terrestrial atmospheric contamination and contained close features of $^{14}$NH$_3$ and $^{15}$NH$_3$, allowing us to derive the ratio from a single spectrum without ambiguity due to radiometric calibration (the primary source of uncertainty in this study). We present the first ground-based determination of Jupiter's $^{15}$N/$^{14}$N ratio (in the range from $1.4\\times10^{-3}$ to $2.5\\times10^{-3}$), which is consistent...

  5. MUSIC in triple-resonance experiments: amino acid type-selective (1)H-(15)N correlations

    Science.gov (United States)

    Schubert; Smalla; Schmieder; Oschkinat

    1999-11-01

    Amino acid type-selective triple-resonance experiments can be of great help for the assignment of protein spectra, since they help to remove ambiguities in either manual or automated assignment procedures. Here, modified triple-resonance experiments that yield amino acid type-selective (1)H-(15)N correlations are presented. They are based on novel coherence transfer schemes, the MUSIC pulse sequence elements, that replace the initial INEPT transfer and are selective for XH(2) or XH(3) (X can be (15)N or (13)C). The desired amino acid type is thereby selected based on the topology of the side chain. Experiments for Gly (G-HSQC); Ala (A-HSQC); Thr, Val, Ile, and Ala (TAVI-HSQC); Thr and Ala (TA-HSQC), as well as Asn and Gln (N-HSQC and QN-HSQC), are described. The new experiments are recorded as two-dimensional experiments and therefore need only small amounts of spectrometer time. The performance of the experiments is demonstrated with the application to two protein domains. Copyright 1999 Academic Press.

  6. Study on Nitrogen Forms in Phenolic Polymers Incorporating Protien by 15N CP—MAS NMR

    Institute of Scientific and Technical Information of China (English)

    CHENGLILI; WENQIXIAO; 等

    1996-01-01

    Phenolic polymers synthesized by reactions by reactions of p-benzoquinone with 15N-labelled protein or (15NH4)2SO4 were studied by using 15N CP-MAS NMR technique in combination with chemical approaches.Results showed that more than 80% of nitrogen in quinone-protein polymers was in the form of amide with some present as aromatic and /or aliphatic amine and less than 10% of nitrogen occurred as heterocyclic N.The nitrogen distribution in the non-hydrolyzable residue of the quinone-protein polymers was basically similar to that of soil humic acid reported in literature with the exception that a higher proportion of N as heterocyclic N and aromatic amine and a lower proportion of N as amide and aliphatic amine were found in the former than in the latter,More than 70% of total nitrogen in quinone-(NH4)2OS4 polymer was acid resistant ,of which about 53% occurred as pyrrole,nitrile and imion type N.The possible roles of the reactions of phenols or quinones with proteins in the formation of humic acid.especially the non-hydrolyzable nitrogen in humicacid,are discussed.

  7. On the width of N-Delta and Delta-Delta states

    CERN Document Server

    Niskanen, J A

    2016-01-01

    It is seen by a coupled-channel calculation that in the two-baryon N-Delta or Delta-Delta system the width of the state is greatly diminished due to the relative kinetic energy of the two baryons, since the internal energy of the particles, available for pionic decay, is smaller. A similar state dependent effect arises from the centrifugal barrier in N-Delta or Delta-Delta systems with non-zero orbital angular momentum. The double-Delta width can become even smaller than the free width of a single Delta. This has some bearing to the interpretation of the d'(2380) resonance recently discovered at COSY.

  8. Sinks for nitrogen inputs in terrestrial ecosystems: a meta-analysis of 15N tracer field studies.

    Science.gov (United States)

    Templer, P H; Mack, M C; Chapin, F S; Christenson, L M; Compton, J E; Crook, H D; Currie, W S; Curtis, C J; Dail, D B; D'Antonio, C M; Emmett, B A; Epstein, H E; Goodale, C L; Gundersen, P; Hobbie, S E; Holland, K; Hooper, D U; Hungate, B A; Lamontagne, S; Nadelhoffer, K J; Osenberg, C W; Perakis, S S; Schleppi, P; Schimel, J; Schmidt, I K; Sommerkorn, M; Spoelstra, J; Tietema, A; Wessel, W W; Zak, D R

    2012-08-01

    Effects of anthropogenic nitrogen (N) deposition and the ability of terrestrial ecosystems to store carbon (C) depend in part on the amount of N retained in the system and its partitioning among plant and soil pools. We conducted a meta-analysis of studies at 48 sites across four continents that used enriched 15N isotope tracers in order to synthesize information about total ecosystem N retention (i.e., total ecosystem 15N recovery in plant and soil pools) across natural systems and N partitioning among ecosystem pools. The greatest recoveries of ecosystem 15N tracer occurred in shrublands (mean, 89.5%) and wetlands (84.8%) followed by forests (74.9%) and grasslands (51.8%). In the short term (ecosystem 15N recovery was negatively correlated with fine-root and soil 15N natural abundance, and organic soil C and N concentration but was positively correlated with mean annual temperature and mineral soil C:N. In the longer term (3-18 months after 15N tracer application), total ecosystem 15N retention was negatively correlated with foliar natural-abundance 15N but was positively correlated with mineral soil C and N concentration and C:N, showing that plant and soil natural-abundance 15N and soil C:N are good indicators of total ecosystem N retention. Foliar N concentration was not significantly related to ecosystem 15N tracer recovery, suggesting that plant N status is not a good predictor of total ecosystem N retention. Because the largest ecosystem sinks for 15N tracer were below ground in forests, shrublands, and grasslands, we conclude that growth enhancement and potential for increased C storage in aboveground biomass from atmospheric N deposition is likely to be modest in these ecosystems. Total ecosystem 15N recovery decreased with N fertilization, with an apparent threshold fertilization rate of 46 kg N x ha(-1) x yr(-1) above which most ecosystems showed net losses of applied 15N tracer in response to N fertilizer addition.

  9. [Quantitative relationship between molecular structure of polychlorinated biphenyls (PCBs) and enthalpy change (deltaH), entropy change (deltaS') in chromatographic process].

    Science.gov (United States)

    Zhang, Qing; Dai, Chaozheng

    2005-09-01

    The relationship between the rule of chromatographic retention value and molecular structure is an important part in the research of chromatographic thermodynamics. The topological index structural parameter JG and the topological index adjoining parameter LJ are put forward. Parameter J(G) describes the correlation of quantity and position of chlorine atoms in polychlorinated biphenyl (PCB) molecules. Parameter L(J) describes the ortho-position correlation of chlorine atoms in PCB molecules. The relational expression between the PCB molecular structures and their enthalpy change (deltaH), entropy change (deltaS') in chromatographic process was discovered. The values of enthalpy change and entropy change for about 140 kinds of polychlorinated biphenyls in chromatographic process on three stationary phases, DB-1, DB-5 and DB-1701, were determined. In comparison with deltaH and deltaS' of the experimental data those calculated from the relational expression had the average relative deviations for deltaH and deltaS' are 0.56% -0.97% and 0.55% - 1.06%, respectively.

  10. Synthesis of 15N omega-hydroxy-L-arginine and ESR and 15N-NMR studies for the elucidation of the molecular mechanism of enzymic nitric oxide formation from L-arginine.

    Science.gov (United States)

    Clement, B; Schnörwangen, E; Kämpchen, T; Mordvintcev, P; Mülsch, A

    1994-12-01

    N omega-Hydroxy-L-arginine (2) was prepared by a multi-stage synthesis; the key step was the addition of hydroxylamine to the protected cyanamide 8. The presence of N-hydroxyguanidines was confirmed, above all, by 15N-NMR investigations. 15N omega-Hydroxy-L-arginine (2) was converted quantitatively to 15NO by NO synthases from macrophages. 15NO was identified by ESR-spectroscopy. These experiments confirm that 15N omega-hydroxy-L-arginine (2) is an intermediate in the biosynthesis of NO from arginine (1) and that the N-hydroxylated N-atom is present in the NO formed.

  11. Resonance strengths in the 14N(p,gamma)15O and 15N(p,alpha gamma)12C reactions

    CERN Document Server

    Marta, Michele; Bemmerer, Daniel; Beyer, Roland; Broggini, Carlo; Caciolli, Antonio; Erhard, Martin; Fülöp, Zsolt; Grosse, Eckart; Gyürky, György; Hannaske, Roland; Junghans, Arnd R; Menegazzo, Roberto; Nair, Chithra; Schwengner, Ronald; Szücs, Tamás; Vezzú, Simone; Wagner, Andreas; Yakorev, Dmitry

    2010-01-01

    The 14N(p,gamma)15O reaction is the slowest reaction of the carbon-nitrogen-oxygen cycle of hydrogen burning in stars. As a consequence, it determines the rate of the cycle. The 15N(p,alpha gamma)12C reaction is frequently used in inverse kinematics for hydrogen depth profiling in materials. The 14N(p,gamma)15O and 15N(p,alpha gamma)12C reactions have been studied simultaneously, using titanium nitride targets of natural isotopic composition and a proton beam. The strengths of the resonances at Ep = 1058 keV in 14N(p,gamma)15O and at Ep = 897 and 430 keV in 15N(p,alpha gamma)12C have been determined with improved precision, relative to the well-known resonance at Ep = 278 keV in 14N(p,gamma)15O. The new recommended values are \\omega\\gamma = 0.352$\\pm$0.018, 362$\\pm$20, and 22.0$\\pm$0.9\\,eV for their respective strengths. In addition, the branching ratios for the decay of the Ep = 1058 keV resonance in 14N(p,gamma)15O have been redetermined. The data reported here should facilitate future studies of off-resona...

  12. geomorphology_delta

    Data.gov (United States)

    California Department of Resources — Surficial geology of the Delta area of California by Brian Atwater of the U.S. Geological Survey. Source maps are from the USGS publication MF-1401. This digital...

  13. Isotopic analysis of bulk, LMW, and HMW DON d15N indicates recycled nitrogen release from marine DON

    Science.gov (United States)

    Knapp, A. N.; Sigman, D. M.; Lipschultz, F.; Kustka, A.; Capone, D. G.

    2010-12-01

    Nitrogen (N) concentration and stable isotope ratio (d15N) measurements were made on bulk and size fractionated surface ocean dissolved organic nitrogen (DON) samples collected in the oligotrophic North Atlantic and Pacific Oceans. The bulk DON concentration in the upper 100 m is similar between the North Atlantic and North Pacific, between 4.5 and 5.0 uM, but the average d15N of bulk DON is significantly different, 3.9 per mil vs. air in the North Atlantic and 4.7 per mil in the North Pacific. The d15N of both bulk and HMW DON from the western tropical North Atlantic are similar to previous measurements, ~4.0 to 4.5 per mil. We report the first measurements of LMW DON d15N, which is consistently lower than HMW DON d15N. Neither the concentration nor d15N of bulk or size-fractionated DON varied with in situ N2 fixation rate, although significant variation in bulk and LMW DON d15N was observed between January and July of the same year in the western tropical North Atlantic. We propose a conceptual model to explain 1) the elevated d15N of bulk DON relative to other surface ocean N pools and fluxes, 2) the elevation of HMW DON d15N relative to LMW DON d15N, and 3) the inter-basin difference in the d15N of bulk DON. In this model, DON is produced from suspended particulate organic nitrogen (PON) without isotope fractionation because the conversion from PON to DON largely does not involve N-bearing bonds. In contrast, deamination and amide hydrolysis, with N isotope effects of 3 to 10 per mil, are major mechanisms by which DON is converted to ammonia and/or to other simple N compounds (e.g., amino acids). Thus these N-specific DON loss reactions result in an elevated d15N of residual DON relative to the parent DON and therefore also to the PON source. Moreover, the ammonium and simple organic N compounds released by microbial DON degradation are efficiently reassimilated back into the PON pool, as an integral part of the regenerated N cycle that further lowers the d15N

  14. Effect of four plant species on soil 15N-access and herbage yield in temporary agricultural grasslands

    DEFF Research Database (Denmark)

    Pirhofter-Walzl, Karin; Eriksen, Jørgen; Rasmussen, Jim

    2013-01-01

    access to greater amounts of soil 15N compared with a shallow-rooting binary mixture, and if leguminous plants affect herbage yield and soil 15N-access. Methods 15N-enriched ammonium-sulphate was placed at three different soil depths (0.4, 0.8 and 1.2 m) to determine the depth dependent soil 15N...... has greater herbage yields than a shallow-rooting two-species mixture and pure stands, if deep-rooting grassland species are superior in accessing soil 15N from 1.2 m soil depth compared with shallow-rooting plant species and vice versa, if a mixture of deep- and shallow-rooting plant species has....... This positive plant diversity effect could not be explained by complementary soil 15N-access of the different plant species from 0.4, 0.8 and 1.2 m soil depths, even though deep-rooting chicory acquired relatively large amounts of deep soil 15N and shallow-rooting perennial ryegrass when grown in a mixture...

  15. {sup 15}N-labeled nitrogen from green manure and ammonium sulfate utilization by the sugarcane ratoon

    Energy Technology Data Exchange (ETDEWEB)

    Ambrosano, Edmilson Jose; Rossi, Fabricio, E-mail: ambrosano@apta.sp.gov.b [Agencia Paulista de Tecnologia dos Agronegocios (APTA), Piracicapa, SP (Brazil). Polo Rigional Centro Sul; Trivelin, Paulo Cesar Ocheuze [Centro de Energia Nuclear na Agricultura (CENA/USP), Piracicaba, SP (Brazil). Lab. de Isotopos Estaveis; Cantarella, Heitor [Agencia Paulista de Tecnologia dos Agronegocios (APTA/IAC), Campinas, SP (Brazil). Instituto Agronomico de Campinas. Centro de Solos e Recursos Agroambientais; Ambrosano, Glaucia Maria Bovi [Universidade de Campinas (UNICAMP/FOP), Piracicaba, SP (Brazil). Fac. de Odontologia de Piracicaba. Dept. de Odontologia Social, Bioestatistica; Schammass, Eliana Aparecida [Agencia Paulista de Tecnologia dos Agronegocios (APTA/IZ), Nova Odessa, SP (Brazil). Instituto de Zootecnia; Muraoka, Takashi [Centro de Energia Nuclear na Agricultura (CENA/USP), Piracicaba, SP (Brazil). Lab. de Fertilidade do solo

    2011-05-15

    Legumes as green manure are alternative sources of nitrogen (N) for crops and can supplement or even replace mineral nitrogen fertilization due to their potential for biological nitrogen fixation (BNF). The utilization of nitrogen by sugarcane (Saccharum spp.) fertilized with sunn hemp (Crotalaria juncea L.) and ammonium sulfate (AS) was evaluated using the {sup 15}N tracer technique. N was added at the rate of 196 and 70 kg ha{sup -1} as {sup 15}N-labeled sunn hemp green manure (SH) and as ammonium sulfate (AS), respectively. Treatments were: (I) Control; (II) AS{sup 15}N; (III) SH{sup 15}N + AS; (IV) SH{sup 15}N; and (V) AS{sup 15}N + SH. Sugarcane was cultivated for five years and was harvested three times. {sup 15}N recovery was evaluated in the two first harvests. In the sum of the three harvests, the highest stalk yields were obtained with a combination of green manure and inorganic N fertilizer; however, in the second cutting the yields were higher where SH was used than in plots with AS. The recovery of N by the first two consecutive harvests accounted for 19 to 21% of the N applied as leguminous green manure and 46 to 49% of the N applied as AS. The amounts of inorganic N, derived from both N sources, present in the 0-0.4 m layer of soil in the first season after N application and were below 1 kg ha{sup -1}. (author)

  16. Delta-Reliability

    OpenAIRE

    Eugster, P.; Guerraoui, R.; Kouznetsov, P.

    2001-01-01

    This paper presents a new, non-binary measure of the reliability of broadcast algorithms, called Delta-Reliability. This measure quantifies the reliability of practical broadcast algorithms that, on the one hand, were devised with some form of reliability in mind, but, on the other hand, are not considered reliable according to the ``traditional'' notion of broadcast reliability [HT94]. Our specification of Delta-Reliability suggests a further step towards bridging the gap between theory and...

  17. Assessing waterbird habitat use in coastal evaporative systems using stable isotopes (δ 13C, δ 15N and δD) as environmental tracers

    Science.gov (United States)

    Ramírez, Francisco; Abdennadher, Aida; Sanpera, Carola; Jover, Lluís; Wassenaar, Leonard I.; Hobson, Keith A.

    2011-04-01

    Isotopic patterns of biota across salinity gradients in man-made evaporative systems could assist in determining the use of these habitats by animals. Here we report δ 13C, δ 15N and δD measurements of a euryhaline fish, the Mediterranean toothcarp ( Aphanius fasciatus), inhabiting a range of salinities in the Thyna saltworks near Sfax (Tunisia). The contribution of these salinity niches to egg formation of two typically piscivorous bird species breeding in the area and feeding within saltworks, Little Tern ( Sternula albifrons) and Little Egret ( Egretta garzetta), was inferred trough a triple-isotope (δ 13C, δ 15N and δD) Bayesian mixing model. Isotopic trends for fish δ 15N and δD across the salinity gradient followed the equations: δ 15N = e (1.1 + 47.68/Salinity) and δD = -175.74 + Salinity + Salinity 2; whereas fish δ 13C increased as salinity rose (δ 13C = -10.83 + 0.02·Salinity), after a sudden drop in fish isotopic values for salinities >60 (Practical Salinity Scale) (average fish δ 13C for salinities <60 = -5.92‰). Both bird species fed largely on low hypersalinity ponds (salinity = 43; average contribution = 37% and 22% for Little Egrets and Little Terns, respectively), although the use of intermediate hypersalinities (salinities 63 and 70) by Little Terns also occurred (16% and 21%, respectively). Isotopic patterns across salinity gradients allow the use of isotopic measurements to inform studies of habitat occupancy within evaporative systems and provide further insights into how wildlife communities interact with them.

  18. Millennial scale oscillations in bulk δ15N and δ13C over the Mid- to Late Holocene seen in proteinaceous corals from the North Pacific Subtropical Gyre

    Science.gov (United States)

    Glynn, D. S.; Mccarthy, M. D.; McMahon, K.; Guilderson, T. P.

    2014-12-01

    The North Pacific Subtropical Gyre (NPSG) is the largest continuous ecosystem on this planet and is an important regulator of biogeochemical cycling and carbon sequestration. With evidence of its expansion in a warming climate, it is necessary to develop a more complete understanding of the variability in productivity and nutrient dynamics in this important ecosystem through time. We constructed a long-term, high resolution record of bulk record of stable nitrogen (δ15N) and carbon isotopes (δ13C) from multiple proteinaceous deep sea corals around Hawaii extending back ~5300 years with few gaps. Our data confirms the decreasing trend in δ15N since the Little Ice Age (1850s), which matches previously published results in part attributed to anthropogenic climate change (e.g. Sherwood et al. 2014). However, while the rate of change since the Little Ice Age (δ15N declines ~1‰ over ~150yrs) remains by far the most rapid throughout the longer record, there also appear to be longer-term (near-millennial scale) climatic oscillations of even greater magnitude (δ15N shifts ~1.5-2‰ over ~1000yrs). After removal of the Seuss Effect, δ13C values also declined ~1.5‰ since the Little Ice Age. Furthermore, there also appear to be oscillations in δ13C of ~1-2‰ over millennial timescales. These results reveal the existence of previously unrecognized long-term oscillations in NPSG biogeochemical cycles, which are likely linked to changes in phytoplankton species composition, food web dynamics, and/or variability in source nutrients and productivity possibly caused by changes in climate. This study provides insight into nutrient dynamics in the NPSG over the past five millennia, and offers a historical baseline to better analyze the effects of current anthropogenic climate forcing.

  19. Discrimination against 15N among recombinant inbred lines of Phaseolus vulgaris L. contrasting in phosphorus use efficiency for nitrogen fixation.

    Science.gov (United States)

    Lazali, Mohamed; Bargaz, Adnane; Carlsson, Georg; Ounane, Sidi Mohamed; Drevon, Jean Jacques

    2014-02-15

    Although isotopic discrimination processes during nitrogen (N) transformations influence the outcome of (15)N based quantification of N2 fixation in legumes, little attention has been given to the effects of genotypic variability and environmental constraints such as phosphorus (P) deficiency, on discrimination against (15)N during N2 fixation. In this study, six Phaseolus vulgaris recombinant inbred lines (RILs), i.e. RILs 115, 104, 34 (P deficiency tolerant) and 147, 83, 70 (P deficiency sensitive), were inoculated with Rhizobium tropici CIAT899, and hydroaeroponically grown with P-sufficient (250 μmol P plant(-1) week(-1)) versus P-deficient (75 μmol P plant(-1) week(-1)) supply. Two harvests were done at 15 (before nodule functioning) and 42 (flowering stage) days after transplanting. Nodulation, plant biomass, P and N contents, and the ratios of (15)N over total N content ((15)N/Nt) for shoots, roots and nodules were determined. The results showed lower (15)N/Nt in shoots than in roots, both being much lower than in nodules. P deficiency caused a larger decrease in (15)N/Nt in shoots (-0.18%) than in nodules (-0.11%) for all of the genotypes, and the decrease in shoots was greatest for RILs 34 (-0.33%) and 104 (-0.25%). Nodule (15)N/Nt was significantly related to both the quantity of N2 fixed (R(2)=0.96***) and the P content of nodules (R(2)=0.66*). We conclude that the discrimination against (15)N in the legume N2-fixing symbiosis of common bean with R. tropici CIAT899 is affected by P nutrition and plant genotype, and that the (15)N/Nt in nodules may be used to screen for genotypic variation in P use efficiency for N2 fixation. Copyright © 2013 Elsevier GmbH. All rights reserved.

  20. Characteristics of the δ ^{15} N_{NO_3 } distribution and its drivers in the Changjiang River estuary and adjacent waters

    Science.gov (United States)

    Wang, Wentao; Yu, Zhiming; Song, Xiuxian; Wu, Zaixing; Yuan, Yongquan; Zhou, Peng; Cao, Xihua

    2016-05-01

    In this study, we conducted investigations in the Changjiang (Yangtze) River estuary and adjacent waters (CREAW) in June and November of 2014. We collected water samples from different depths to analyze the nitrogen isotopic compositions of nitrate, nutrient concentrations (including inorganic N, P, and Si), and other physical and biological parameters, along with the vertical distribution and seasonal variations of these parameters. The compositions of nitrogen isotope in nitrate were measured with the denitrifier method. Results show that the Changjiang River diluted water (CDW) was the main factor aff ecting the shallow waters (above 10 m) of the CREAW, and CDW tended to influence the northern areas in June and the southern areas in November. δ ^{15} N_{NO_3 } values in CDW ranged from 3.21‰-3.55‰. In contrast, the deep waters (below 30 m) were aff ected by the subsurface water of the Kuroshio Current, which intruded into the waters near 31°N in June. The δ ^{15} N_{NO_3 } values of these waters were 6.03‰-7.6‰, slightly higher than the values of the Kuroshio Current. Nitrate assimilation by phytoplankton in the shallow waters of the study area varied seasonally. Because of the favorable temperature and nutrient conditions in June, abundant phytoplankton growth resulted in harmful algae blooms (HABs). Therefore, nitrate assimilation was strong in June and weak in November. The δ ^{15} N_{NO_3 } fractionations caused by assimilation of phytoplankton were 4.57‰ and 4.41‰ in the shallow waters in June and November, respectively. These results are consistent with previous laboratory cultures and in situ investigations. Nitrification processes were observed in some deep waters of the study area, and they were more apparent in November than in June. The fractionation values of nitrification ranged from 24‰-25‰, which agrees with results for Nitrosospira tenuis reported by previous studies.

  1. Natural-abundance 15N NMR studies of Turkey ovomucoid third domain. Assignment of peptide 15N resonances to the residues at the reactive site region via proton-detected multiple-quantum coherence

    Science.gov (United States)

    Ortiz-Polo, Gilberto; Krishnamoorthi, R.; Markley, John L.; Live, David H.; Davis, Donald G.; Cowburn, David

    Heteronuclear two-dimensional 1H{ 15N} multiple-quantum (MQ) spectroscopy has been applied to a protein sample at natural abundance: ovomucoid third domain from turkey ( Meleagris gallopavo), a serine proteinase inhibitor of 56 amino acid residues. Peptide amide 1H NMR assignments obtained by two-dimensional 1H{ 1H} NMR methods (R. Krishnamoorthi and J. L. Markley, unpublished data) led to identification of the corresponding 1H{ 15N} MQ coherence cross peaks. From these, 15N NMR chemical shifts were determined for several specific backbone amide groups of amino acid residues located around the reactive site region of the inhibitor. The results suggest that amide 15N chemical shifts, which are readily obtained in this way, may serve as sensitive probes for conformational studies of proteins.

  2. Temporal variations of C, N, δ13C, and δ15N in organic matter collected by a sediment trap at Cuenca Alfonso, Bahía de La Paz, SW Gulf of California

    Science.gov (United States)

    Aguiñiga, Sergio; Sanchez, Alberto; Silverberg, Norman

    2010-09-01

    To monitor the composition and the vertical flux of particulate matter from the sea surface, a sediment trap was moored in Cuenca Alfonso, Bahía de La Paz, a zone of high productivity in the southwestern Gulf of California. Carbonate-free samples from 2002 to 2005 were analyzed for C org, N, δ13C, and δ15N. The results show seasonal and interannual variability, with the δ13C and δ15N values larger in spring and summer than in fall and winter. The C:N ratio and δ13C increased by 1.5 units from 2002 to 2003-2005, suggesting a change in the supply of organic matter and-or the use or preferential degradation of N org. There was no interannual variation in δ15N. The occasional high δ15N values suggest that physical mechanisms, such as the shoaling and advection into the bay of 15N-rich subsurface equatorial water, occur over short time periods. The latter is presumed to be related to the periodic development of a significant cyclonic gyre in the southern Gulf.

  3. 1H, 13C, and 15N resonance assignments of murine amelogenin, an enamel biomineralization protein.

    Energy Technology Data Exchange (ETDEWEB)

    Buchko, Garry W.; Bekhazi, Jacky G.; Cort, John R.; Valentine, Nancy B.; Snead, Malcolm L.; Shaw, Wendy J.

    2008-06-01

    Amelogenin is the predominant matrix protein in developing dental enamel. Making extensive use of residue-specific 15N-labeled amino acids samples, the majority of the main and side chain resonances for murine amelogenin were assigned in 2% aqueous acetic acid at pH 3.0. This research was performed at Pacific Northwest National Laboratory, operated by Battelle for the US-DOE. A large part of this research was performed at the W.R. Wiley Environmental Molecular Sciences Laboratory, a national scientific user facility sponsored by U.S. Department of Energy’s Office of Biological and Environmental Research (BER) program located at Pacific Northwest National Laboratory (PNNL).

  4. 15N-Labelled Fertilizer Recovery by Sweet Sorghum in Mediterranean Climate

    Directory of Open Access Journals (Sweden)

    Michele Perniola

    2008-12-01

    Full Text Available A 15N-labelled fertilization trial was carried out on sweet sorghum, grown in semi-arid environments of southern Europe with the aim to monitor the efficiency and effectiveness of the N-fertilisation technique under irrigation and different nitrogen fertilization rates, in factorial combination. A rainfed condition was compared with a full irrigation treatment (100% restoration of total crop water consumption, in a similar way, an unfertilized control was tested with respect to N application rates of 60 and 120 Kg ha-1, respectively. The fertilisation efficiency measured directly through the isotope discrimination technique was on average equal to 15%. The aliquot of nitrogen released by the fertiliser into the soil and not absorbed by the plant becomes part of the different components of the soil nitrogen balance, regardless of its origin.

  5. Wanted: dead or alive? Isotopic analysis (δ13C and δ15N) of Pygoscelis penguin chick tissues supports opportunistic sampling.

    Science.gov (United States)

    Vasil, Christopher A; Polito, Michael J; Patterson, William P; Emslie, Steven D

    2012-03-15

    Physiological stress and starvation have been shown to affect δ(13)C and δ(15)N isotope values and, given that animals often die from starvation, the cause of death may be an important factor to consider in stable isotope analyses of opportunistically collected samples. We addressed this issue by comparing tissue stable isotope values of living and deceased Adélie (Pygoscelis adeliae) and Chinstrap Penguin (P. antarctica) chicks collected from the same respective populations. No significant difference was found between living and deceased penguin chick feather, down, and toenail isotope values and both groups displayed similar isotopic trends between tissue types. In addition, similar relationships were observed between both species and across several seasons. Furthermore, sub-dermal adiposity and cause of death (starvation and/or predation) had no significant effect on the δ(13)C and δ(15)N values. Our findings suggest that tissues from deceased penguins can be isotopically representative of tissues obtained from the living population, despite the cause of death, and support the use of opportunistic sampling in stable isotope analyses. Copyright © 2012 John Wiley & Sons, Ltd.

  6. Regional patterns of δ13C and δ15N stable isotopes of size-fractionated zooplankton in the western tropical North Pacific Ocean

    Science.gov (United States)

    Yang, Guang; Li, Chaolun; Guilini, Katja; Wang, Xiaocheng; Wang, Yanqing

    2017-02-01

    Zooplankton play a prominent role in the biogeochemical cycles of marine ecosystems. Little is known about the trophodynamics of zooplankton in response to geographic patterns in isotopic baselines and physical processes in the western tropical North Pacific. In this study, stable isotope ratios of five size fractions of zooplankton (100 to >2000 μm) from different current regions in the western tropical North Pacific Ocean were analyzed. Both δ13C and δ15N isotopic values increased with zooplankton size class. The largest zooplankton group (>2000 μm), with a diverse composition, showed relatively higher stable isotope signatures, covering a wider range. Regional variations in the zooplankton stable isotope signatures were similar across all size classes, with generally higher values in the North Equatorial Counter Current (NECC) and the North Equatorial Current (NEC) and lower values in the Subtropical Counter Current (STCC). These regional patterns of zooplankton isotope signatures were consistent with the variation of oceanographic features (temperature, salinity, nutrients, chlorophyll a) and were also related to the isotopic baselines of particulate organic matter (POM) in the different current regions. Moreover, the nitrogen-fixing cyanobacteria Trichodesmium spp. may be the main contributor to low δ15N values in the STCC. The results of this study demonstrate the influence of physical processes on the stable isotopic signatures of zooplankton. This baseline information is crucial for future food web studies in the western tropical North Pacific Ocean.

  7. Complementary constraints from carbon (13C) and nitrogen (15N) isotopes on the glacial ocean's soft-tissue biological pump

    Science.gov (United States)

    Schmittner, A.; Somes, C. J.

    2016-06-01

    A three-dimensional, process-based model of the ocean's carbon and nitrogen cycles, including 13C and 15N isotopes, is used to explore effects of idealized changes in the soft-tissue biological pump. Results are presented from one preindustrial control run (piCtrl) and six simulations of the Last Glacial Maximum (LGM) with increasing values of the spatially constant maximum phytoplankton growth rate μmax, which accelerates biological nutrient utilization mimicking iron fertilization. The default LGM simulation, without increasing μmax and with a shallower and weaker Atlantic Meridional Overturning Circulation and increased sea ice cover, leads to 280 Pg more respired organic carbon (Corg) storage in the deep ocean with respect to piCtrl. Dissolved oxygen concentrations in the colder glacial thermocline increase, which reduces water column denitrification and, with delay, nitrogen fixation, thus increasing the ocean's fixed nitrogen inventory and decreasing δ15NNO3 almost everywhere. This simulation already fits sediment reconstructions of carbon and nitrogen isotopes relatively well, but it overestimates deep ocean δ13CDIC and underestimates δ15NNO3 at high latitudes. Increasing μmax enhances Corg and lowers deep ocean δ13CDIC, improving the agreement with sediment data. In the model's Antarctic and North Pacific Oceans modest increases in μmax result in higher δ15NNO3 due to enhanced local nutrient utilization, improving the agreement with reconstructions there. Models with moderately increased μmax fit both isotope data best, whereas large increases in nutrient utilization are inconsistent with nitrogen isotopes although they still fit the carbon isotopes reasonably well. The best fitting models reproduce major features of the glacial δ13CDIC, δ15N, and oxygen reconstructions while simulating increased Corg by 510-670 Pg compared with the preindustrial ocean. These results are consistent with the idea that the soft-tissue pump was more efficient

  8. Organically treated biochar increases plant production and reduces N2O emissions: mechanistic insights by 15N tracing

    Science.gov (United States)

    Kammann, Claudia; Messerschmidt, Nicole; Clough, Tim; Schmidt, Hans-Peter; Marhan, Sven; Koyro, Hans-Werner; Steffens, Diedrich; Müller, Christoph

    2014-05-01

    Pyrogenic carbon (biochar) offers considerable potential for carbon capture and soil storage (CCSS) compared to other, less recalcitrant soil-C additives. Recent meta-analysis demonstrated that it can significantly reduce agricultural N2O emissions. Freshly produced biochars, however, do not always have yield-improving effects, i.e. there is no immediate economic incentive for using it. Hence, combining biochar with organic nutrient-rich amendments may be a promising agricultural strategy to accelerate CCSS, but it is unclear if biochar still reduces N2O emissions, in particular when it may act as nutrient carrier. We explored the potential of biochar to improve the GHG-cost/yield ratio and thereby its socio-economic value as soil amendment in two subsequent studies under controlled conditions: (1) A proof-of-concept study where the effects of untreated biochar were compared to those of co-composted biochar combined with stepwise improved nutritional regimes (+/- compost; +/- mineral-N application), and (2) a 15N-labeling-tracing study to unravel N exchange on biochar particles and N2O production and reduction mechanisms. Both studies were carried out in nutrient-poor sandy soils, the most likely initial target soils for biochar-CCSS strategies. While the untreated biochar reduced plant growth under N-limiting conditions, or at best did not reduce it, the co-composted biochar always significantly stimulated plant growth. The relative stimulation was largest with the lowest nutrient additions (305% versus 61% of control with untreated biochar). Electro-ultra-filtration analyses revealed that the co-composted but not the untreated biochar carried considerable amounts of easily extractable as well as more strongly sorbed plant nutrients, in particular nitrate and phosphorus. The subsequent 15N labelling-tracing study revealed that the co-composted biochar still (i) acted as a mineral-N exchange site for nitrate and ammonium despite its N-preloading, (ii) reduced N2O

  9. A combined HNCA/HNCO experiment for {sup 15}N labeled proteins with {sup 13}C at natural abundance

    Energy Technology Data Exchange (ETDEWEB)

    Kupce, Eriks [Varian Inc. (United Kingdom); Muhandiram, D.R.; Kay, Lewis E. [University of Toronto, Protein Engineering Network Centers of Excellence and Departments of Medical Genetics, Biochemistry and Chemistry (Canada)], E-mail: kay@pound.med.utoronto.ca

    2003-10-15

    A triple resonance NMR experiment is presented for the simultaneous recording of HNCA and HNCO data sets on {sup 15}N, natural abundance {sup 13}C samples. The experiment exploits the fact that transfers of magnetization from {sup 15}N to {sup 13}CO and from {sup 15}N to {sup 13}C{sup {alpha}} (and back) proceed independently for samples that are not enriched in {sup 13}C. A factor of 2 in measuring time is gained by recording the two data sets simultaneously with no compromise in spectral quality. An application to a 0.5 mM {sup 15}N labeled sample of protein-L is presented with all expected correlations observed in spectra recorded with a cryogenic probe at 500 MHz.

  10. A suite of Mathematica notebooks for the analysis of protein main chain 15N NMR relaxation data.

    Science.gov (United States)

    Spyracopoulos, Leo

    2006-12-01

    A suite of Mathematica notebooks has been designed to ease the analysis of protein main chain 15N NMR relaxation data collected at a single magnetic field strength. Individual notebooks were developed to perform the following tasks: nonlinear fitting of 15N-T1 and -T2 relaxation decays to a two parameter exponential decay, calculation of the principal components of the inertia tensor from protein structural coordinates, nonlinear optimization of the principal components and orientation of the axially symmetric rotational diffusion tensor, model-free analysis of 15N-T1, -T2, and {1H}-15N NOE data, and reduced spectral density analysis of the relaxation data. The principle features of the notebooks include use of a minimal number of input files, integrated notebook data management, ease of use, cross-platform compatibility, automatic visualization of results and generation of high-quality graphics, and output of analyses in text format.

  11. Stipa tenacissima Does not Affect the Foliar δ13C and δ15N of Introduced Shrub Seedlings in a Mediterranean Semi-arid Steppe

    Institute of Scientific and Technical Information of China (English)

    Fernando T. Maestre; Susana Bautista; Jordi Cortina

    2006-01-01

    Recent studies have shown that the tussock grass Stipa tenacissima L. facilitates the establishment of late-successional shrubs, in what constitutes the first documented case of facilitation of woody plants by grasses. With the aim of increasing our knowledge of this interaction, in the present study we investigated the effects of S. tenacissima on the foliar δ13C, δ15N, nitrogen concentration, and carbon: nitrogen ratio of introduced seedlings of Pistacia lentiscus L., Quercus coccifera L., and Medicago arborea L. in a semi-arid Mediterranean steppe. Six months after planting, the values of δ13C ranged between -26.9‰ and -29.6‰,whereas those of δ15N ranged between -1.9‰ and 2.7‰. The foliar C: N ratio ranged between 10.7 and 53.5,and the nitrogen concentration ranged between 1.0% and 4.4%. We found no significant effect of the microsite provided by S. tenacissima on these variables in any of the species evaluated. The values of δ13C were negatively correlated with predawn water potentials in M. arborea and were positively correlated with relative growth rate in Q. coccifera. The values of δ15N were positively correlated with the biomass allocation to roots in the latter species. The present results suggest that the modification of environmental conditions in the are surrounding S. tenacissima was not strong enough to modify the foliar isotopic and nitrogen concentration of shrubs during the early stages after planting.

  12. Arsenic contamination in the freshwater fish ponds of Pearl River Delta: bioaccumulation and health risk assessment.

    Science.gov (United States)

    Cheng, Zhang; Chen, Kun-Ci; Li, Kai-Bin; Nie, Xiang-Ping; Wu, Sheng Chun; Wong, Chris Kong-Chu; Wong, Ming-Hung

    2013-07-01

    This study investigated the extent of arsenic (As) contamination in five common species of freshwater fish (northern snakehead [Channa argus], mandrarin fish [Siniperca chuatsi], largemouth bass [Lepomis macrochirous], bighead carp [Aristichthys nobilis] and grass carp [Ctenopharyngodon idellus]) and their associated fish pond sediments collected from 18 freshwater fish ponds around the Pearl River Delta (PRD). The total As concentrations detected in fish muscle and sediment in freshwater ponds around the PRD were 0.05-3.01 mg kg(-1) wet weight (w. wt) and 8.41-22.76 mg kg(-1) dry weight (d. wt), respectively. In addition, the As content was positively correlated (p < 0.05) to total organic carbon (TOC) contents in sediments. Biota sediment accumulation factor (BSAF) showed that omnivorous fish and zooplankton accumulated higher concentrations of heavy metals from the sediment than carnivorous fish. In addition, feeding habits of fish also influence As accumulation in different fish species. In this study, two typical food chains of the aquaculture ponds were selected for investigation: (1) omnivorous food chain (zooplankton, grass carp and bighead carp) and (2) predatory food chain (zooplankton, mud carp and mandarin fish). Significant linear relationships were obtained between log As and δ (15)N. The slope of the regression (-0.066 and -0.078) of the log transformed As concentrations and δ (15)N values, as biomagnifications power, indicated there was no magnification or diminution of As from lower trophic levels (zooplankton) to fish in the aquaculture ponds. Consumption of largemouth bass, northern snakehead and bighead carp might impose health risks of Hong Kong residents consuming these fish to the local population, due to the fact that its cancer risk (CR) value exceeded the upper limit of the acceptable risk levels (10(-4)) stipulated by the USEPA.

  13. An optimized method for {sup 15}N R{sub 1} relaxation rate measurements in non-deuterated proteins

    Energy Technology Data Exchange (ETDEWEB)

    Gairí, Margarida, E-mail: mgairi@rmn.ub.edu [University of Barcelona (CCiTUB), NMR Facility, Scientific and Technological Centers (Spain); Dyachenko, Andrey [Institute for Research in Biomedicine (IRB) (Spain); González, M. Teresa; Feliz, Miguel [University of Barcelona (CCiTUB), NMR Facility, Scientific and Technological Centers (Spain); Pons, Miquel [University of Barcelona, Biomolecular NMR Laboratory and Organic Chemistry Department (Spain); Giralt, Ernest, E-mail: ernest.giralt@irbbarcelona.org [Institute for Research in Biomedicine (IRB) (Spain)

    2015-06-15

    {sup 15}N longitudinal relaxation rates are extensively used for the characterization of protein dynamics; however, their accurate measurement is hindered by systematic errors. {sup 15}N CSA/{sup 1}H–{sup 15}N dipolar cross-correlated relaxation (CC) and amide proton exchange saturation transfer from water protons are the two main sources of systematic errors in the determination of {sup 15}N R{sub 1} rates through {sup 1}H–{sup 15}N HSQC-based experiments. CC is usually suppressed through a train of 180° proton pulses applied during the variable {sup 15}N relaxation period (T), which can perturb water magnetization. Thus CC cancellation is required in such a way as to minimize water saturation effects. Here we examined the level of water saturation during the T period caused by various types of inversion proton pulses to suppress CC: (I) amide-selective IBURP-2; (II) cosine-modulated IBURP-2; (III) Watergate-like blocks; and (IV) non-selective hard. We additionally demonstrate the effect of uncontrolled saturation of aliphatic protons on {sup 15}N R{sub 1} rates. In this paper we present an optimized pulse sequence that takes into account the crucial effect of controlling also the saturation of the aliphatic protons during {sup 15}N R{sub 1} measurements in non-deuterated proteins. We show that using cosine-modulated IBURP-2 pulses spaced 40 ms to cancel CC in this optimized pulse program is the method of choice to minimize systematic errors coming from water and aliphatic protons saturation effects.

  14. Species specific and environment induced variation of δ13C and δ15N in alpine plants

    Directory of Open Access Journals (Sweden)

    Yang eYang

    2015-06-01

    Full Text Available Stable carbon and nitrogen isotope signals in plant tissues integrate plant-environment interactions over long periods. In this study, we hypothesized that humid alpine life conditions are narrowing the scope for significant deviations from common carbon, water and nitrogen relations as captured by stable isotope signals. We explored the variation in δ13C and δ15N in 32 plant species from tissue type to ecosystem scale across a suite of locations at c. 2500 m elevation in the Swiss Alps. Foliar δ13C and δ15N varied among species by about 3-4 ‰ and 7-8 ‰ respectively. However, there was no overall difference in means of δ13C and δ15N for species sampled in different plant communities or when bulk plant dry matter harvests of different plant communities were compared. δ13C was found to be highly species specific, so that the ranking among species was mostly maintained across 11 habitats. However, δ15N varied significantly from place to place in all species (a range of 2.7 ‰ except in Fabaceae (Trifolium alpinum and Juncaceae (Luzula lutea. There was also a substantial variation among individuals of the same species collected next to each other. No difference was found in foliar δ15N of non-legumes, which were either collected next to or away from the most common legume, T. alpinum. δ15N data place Cyperaceae and Juncaceae, just like Fabaceae, in a low discrimination category, well separated from other families. Soil δ15N was higher than in plants and increased with soil depth. The results indicate a high functional diversity in alpine plants that is similar to that reported for low elevation plants. We conclude that the surprisingly high variation in δ13C and δ15N signals in the studied high elevation plants is largely species specific (genetic and insensitive to obvious environmental cues.

  15. 15N Abundance of Nodules as an Indicator of N Metabolism in N2-Fixing Plants 1

    Science.gov (United States)

    Shearer, Georgia; Feldman, Lori; Bryan, Barbara A.; Skeeters, Jerri L.; Kohl, Daniel H.; Amarger, Nöelle; Mariotti, Françoise; Mariotti, André

    1982-01-01

    This paper expands upon previous reports of 15N elevation in nodules (compared to other tissues) of N2-fixing plants. N2-Fixing nodules of Glycine max (soybeans), Vigna unguiculata (cowpea), Phaseolus vulgaris (common bean), Phaseolus coccineus (scarlet runner bean), Prosopis glandulosa (mesquite), and Olneya tesota (desert ironwood) were enriched in 15N. Nodules of Vicia faba (fava beans), Arachis hypogaea (peanut), Trifolium pratense (red clover), Pisum sativum (pea), Lathyrus sativus (grass pea), Medicago sativa (alfalfa), and Lupinus mutabilis (South American lupine) were not; nor were the nodules of nine species of N2-fixing nonlegumes. The nitrogen of ineffective nodules of soybeans and cowpeas was not enriched in 15N. Thus, 15N elevation in nodules of these plants depends on active N2-fixation. Results obtained so far on the generality of 15N enrichment in N2-fixing nodules suggest that only the nodules of plants which actively fix N2 and which transport allantoin or allantoic acid exhibit 15N enrichment. PMID:16662517

  16. Lineshape-based polarimetry of dynamically-polarized (15)N2O in solid-state mixtures.

    Science.gov (United States)

    Kuzma, N N; Håkansson, P; Pourfathi, M; Ghosh, R K; Kara, H; Kadlecek, S J; Pileio, G; Levitt, M H; Rizi, R R

    2013-09-01

    Dynamic nuclear polarization (DNP) of (15)N2O, known for its long-lived singlet-state order at low magnetic field, is demonstrated in organic solvent/trityl mixtures at ∼1.5 K and 5 T. Both (15)N polarization and intermolecular dipolar broadening are strongly affected by the sample's thermal history, indicating spontaneous formation of N2O clusters. In situ (15)N NMR reveals four distinct powder-pattern spectra, attributed to the chemical-shift anisotropy (CSA) tensors of the two (15)N nuclei, further split by the intramolecular dipolar coupling between their magnetic moments. (15)N polarization is estimated by fitting the free-induction decay (FID) signals to the analytical model of four single-quantum transitions. This analysis implies (10.2±2.2)% polarization after 37 h of DNP, and provides a direct, instantaneous probe of the absolute (15)N polarization, without a need for time-consuming referencing to a thermal-equilibrium NMR signal. Copyright © 2013 Elsevier Inc. All rights reserved.

  17. Afforestation impacts microbial biomass and its natural (13)C and (15)N abundance in soil aggregates in central China.

    Science.gov (United States)

    Wu, Junjun; Zhang, Qian; Yang, Fan; Lei, Yao; Zhang, Quanfa; Cheng, Xiaoli

    2016-10-15

    We investigated soil microbial biomass and its natural abundance of δ(13)C and δ(15)N in aggregates (>2000μm, 250-2000μm, 53-250μm and plantations) soils, adjacent croplands and open area (i.e., control) in the Danjiangkou Reservoir area of central China. The afforested soils averaged higher microbial biomass carbon (MBC) and nitrogen (MBN) levels in all aggregates than in open area and cropland, with higher microbial biomass in micro-aggregates (2000μm). The δ(13)C of soil microbial biomass was more enriched in woodland soils than in other land use types, while δ(15)N of soil microbial biomass was more enriched compared with that of organic soil in all land use types. The δ(13)C and δ(15)N of microbial biomass were positively correlated with the δ(13)C and δ(15)N of organic soil across aggregates and land use types, whereas the (13)C and (15)N enrichment of microbial biomass exhibited linear decreases with the corresponding C:N ratio of organic soil. Our results suggest that shifts in the natural (13)C and (15)N abundance of microbial biomass reflect changes in the stabilization and turnover of soil organic matter (SOM) and thereby imply that afforestation can greatly impact SOM accumulation over the long-term. Copyright © 2016 Elsevier B.V. All rights reserved.

  18. Elastic and inelastic scattering of {sup 15}N ions by {sup 9}Be at 84 MeV

    Energy Technology Data Exchange (ETDEWEB)

    Rudchik, A.T., E-mail: rudchik@kinr.kiev.ua [Institute for Nuclear Research, Ukrainian Academy of Sciences, Prospect Nauki 47, 03680 Kyiv (Ukraine); Chercas, K.A. [Institute for Nuclear Research, Ukrainian Academy of Sciences, Prospect Nauki 47, 03680 Kyiv (Ukraine); Kemper, K.W. [Physics Department, Florida State University, Tallahassee, FL 32306-4350 (United States); Rusek, K. [Heavy Ion Laboratory of Warsaw University, ul. L. Pasteura 5A, PL-02-093 Warsaw (Poland); Rudchik, A.A.; Herashchenko, O.V. [Institute for Nuclear Research, Ukrainian Academy of Sciences, Prospect Nauki 47, 03680 Kyiv (Ukraine); Koshchy, E.I. [Kharkiv National University, pl. Svobody 4, 61077 Kharkiv (Ukraine); Pirnak, Val.M. [Institute for Nuclear Research, Ukrainian Academy of Sciences, Prospect Nauki 47, 03680 Kyiv (Ukraine); Piasecki, E.; Trzcińska, A. [Heavy Ion Laboratory of Warsaw University, ul. L. Pasteura 5A, PL-02-093 Warsaw (Poland); Sakuta, S.B. [Russian Research Center “Kurchatov Institute”, Kurchatov Sq. 1, 123182 Moscow (Russian Federation); Siudak, R. [H. Niewodniczański Institute of Nuclear Physics, Polish Academy of Sciences, ul. Radzikowskiego 152, PL-31-342 Cracow (Poland); Strojek, I. [National Center for Nuclear Researches, ul. Hoża 69, PL-00-681 Warsaw (Poland); Stolarz, A. [Heavy Ion Laboratory of Warsaw University, ul. L. Pasteura 5A, PL-02-093 Warsaw (Poland); Ilyin, A.P.; Ponkratenko, O.A.; Stepanenko, Yu.M.; Shyrma, Yu.O. [Institute for Nuclear Research, Ukrainian Academy of Sciences, Prospect Nauki 47, 03680 Kyiv (Ukraine); Szczurek, A. [H. Niewodniczański Institute of Nuclear Physics, Polish Academy of Sciences, ul. Radzikowskiego 152, PL-31-342 Cracow (Poland); Uleshchenko, V.V. [Institute for Nuclear Research, Ukrainian Academy of Sciences, Prospect Nauki 47, 03680 Kyiv (Ukraine)

    2016-03-15

    Angular distributions of the {sup 9}Be + {sup 15}N elastic and inelastic scattering were measured at E{sub lab}({sup 15}N) = 84 MeV (E{sub c.m.} = 31.5 MeV) for the 0–6.76 MeV states of {sup 9}Be and 0–6.32 MeV states of {sup 15}N. The data were analyzed within the optical model and coupled-reaction-channels method. The elastic and inelastic scattering, spin reorientations of {sup 9}Be in ground and excited states and {sup 15}N in excited states as well as the most important one- and two-step transfer reactions were included in the channels-coupling scheme. The parameters of the {sup 9}Be + {sup 15}N optical potential of Woods–Saxon form as well as deformation parameters of these nuclei were deduced. The analysis showed that the {sup 9}Be + {sup 15}N pure potential elastic scattering dominates at the forward angles whereas the ground state spin reorientation of {sup 9}Be gives a major contribution to the elastic scattering cross sections at the large angles. Contributions from particle transfers are found to be negligible for the present scattering system.

  19. Single Particle Strengths and Mirror States in $^{15}$N$-^{15}$O below 12.0 MeV

    CERN Document Server

    Mertin, C E; Crisp, A M; Keeley, N; Kemper, K W; Momtyuk, O; Roeder, B T; Volya, A

    2014-01-01

    New $^{14}$N(d,p) angular distribution data were taken at a deuteron bombarding energy of 16 MeV to locate all narrow single particle neutron states up to 15 MeV in excitation. A new shell model calculation is able to reproduce all levels in $^{15}$N up to 11.5 MeV and is used to characterize a narrow single particle level at 11.236 MeV and to provide a map of the single particle strengths. The known levels in $^{15}$N are then used to determine their mirrors in the lesser known nucleus $^{15}$O. The 2s$_{1/2}$ and 1d$_{5/2}$ single particle centroid energies are determined for the $^{15}$N$-^{15}$O mirror pair as: $^{15}$N $(\\text{2s}_{1/2}) = 8.08$ MeV, $^{15}$O $(\\text{2s}_{1/2}) = 7.43$ MeV, $^{15}$N $(\\text{1d}_{5/2}) = 7.97$ MeV, and $^{15}$O $(\\text{1d}_{5/2}) = 7.47$ MeV. These results confirm the degeneracy of these orbits and that the $^{15}$N$-^{15}$O nuclei are where the transition between the $\\text{2s}_{1/2}$ lying below the $\\text{1d}_{5/2}$ to lying above it, takes place. The $\\text{1d}_{3/2}$...

  20. Sedimentary records of δ(13)C, δ(15)N and organic matter accumulation in lakes receiving nutrient-rich mine waters.

    Science.gov (United States)

    Widerlund, Anders; Chlot, Sara; Öhlander, Björn

    2014-07-01

    Organic C and total N concentrations, C/N ratios, δ(15)N and δ(13)C values in (210)Pb-dated sediment cores were used to reconstruct historical changes in organic matter (OM) accumulation in three Swedish lakes receiving nutrient-rich mine waters. Ammonium-nitrate-based explosives and sodium cyanide (NaCN) used in gold extraction were the major N sources, while lesser amounts of P originated from apatite and flotation chemicals. The software IsoSource was used to model the relative contribution of soil, terrestrial and littoral vegetation, and phytoplankton detritus in the lake sediments. In one lake the IsoSource modelling failed, suggesting the presence of additional, unknown OM sources. In two of the lakes sedimentary detritus of littoral vegetation and phytoplankton had increased by 15-20% and 20-35%, respectively, since ~1950, when N- and P-rich mine waters began to reach the lakes. Today, phytoplankton is the dominating OM component in these lake sediments, which appears to be a eutrophication effect related to mining operations. Changes in the N isotopic composition of biota, lake water, and sediments related to the use of ammonium-nitrate-based explosives and NaCN were evident in the two studied systems. However, N isotope signals in the receiving waters (δ(15)N~+9‰ to +19‰) were clearly shifted from the primary signal in explosives (δ(15)N-NO3=+3.4±0.3‰; δ(15)N-NH4=-8.0±0.3‰) and NaCN (δ(15)N=+1.1±0.5‰), and direct tracing of the primary N isotope signals in mining chemicals was not possible in the receiving waters. Systems where mine waters with a well known discharge history are a major point source of N with well-defined isotopic composition should, however, be suitable for further studies of processes controlling N isotope signatures and their transformation in aquatic systems receiving mine waters.

  1. {\\delta}M Formalism

    CERN Document Server

    Talebian-Ashkezari, Alireza; Abolhasani, Ali Akbar

    2016-01-01

    We study the evolution of the "non-perturbative" metric perturbations in a Bianchi background in the long-wavelength limit. By applying the gradient expansion to the equations of motion we exhibit a generalized "Separate Universe" approach to the cosmological perturbation theory. Having found this consistent separate universe picture, we introduce the "{\\delta}M formalism" for calculating the evolution of the tensor perturbations in anisotropic inflation models in almost similar way as the so-called {\\delta}N formula for the super-horizon dynamics of the curvature perturbations. Likewise its ancestor, {\\delta}N formalism, this new method can substantially reduce the amount of calculations related to the evolution of the tensor modes.

  2. Delta-Bar-Delta and directed random search algorithms to study capacitor banks switching overvoltages

    Directory of Open Access Journals (Sweden)

    Sadeghkhani Iman

    2012-01-01

    Full Text Available This paper introduces an approach to analyse transient overvoltages during capacitor banks switching based on artificial neural networks (ANN. Three learning algorithms, delta-bar-delta (DBD, extended delta-bar-delta (EDBD and directed random search (DRS were used to train the ANNs. The ANN training is based on equivalent parameters of the network and therefore, a trained ANN is applicable to every studied system. The developed ANN is trained with extensive simulated results and tested for typical cases. The new algorithms are presented and demonstrated for a partial 39-bus New England test system. The simulated results show the proposed technique can accurately estimate the peak values of switching overvoltages.

  3. Structural Dynamics of the Potassium Channel Blocker ShK: SRLS Analysis of (15)N Relaxation.

    Science.gov (United States)

    Meirovitch, Eva; Tchaicheeyan, Oren; Sher, Inbal; Norton, Raymond S; Chill, Jordan H

    2015-12-10

    The 35-residue ShK peptide binds with high affinity to voltage-gated potassium channels. The dynamics of the binding surface was studied recently with (microsecond to millisecond) (15)N relaxation dispersion and (picosecond to nanosecond) (15)N spin relaxation of the N-H bonds. Relaxation dispersion revealed microsecond conformational-exchange-mediated exposure of the functionally important Y23 side chain to the peptide surface. The spin relaxation parameters acquired at 14.1 and 16.45 T have been subjected to model-free (MF) analysis, which yielded a squared generalized order parameter, S(2), of approximately 0.85 for virtually all of the N-H bonds. Only a "rigid backbone" evaluation could be inferred. We ascribe this limited information to the simplicity of MF in the context of challenging data. To improve the analysis, we apply the slowly relaxing local structure (SRLS) approach, which is a generalization of MF. SRLS describes N-H bond dynamics in ShK in terms of a local potential, u, ranging from 10 to 18.5 kBT, and a local diffusion rate, D2, ranging from 4.2 × 10(8) to 2.4 × 10(10) s(-1). This analysis shows that u is outstandingly strong for Y23 and relatively weak for K22, whereas D2 is slow for Y23 and fast for K22. These observations are relevant functionally because of the key role of the K22-Y23 dyad in ShK binding to potassium channels. The disulfide-bond network exhibits a medium-strength potential and an alternating wave-like D2 pattern. This is indicative of moderate structural restraints and motional plasticity, in support of, although not directly correlated with, the microsecond binding-related conformational exchange process detected previously. Thus, new information on functionally important residues in ShK and its overall conformational stability emerged from the SRLS analysis, as compared with the previous MF-based estimate of backbone dynamics as backbone rigidity.

  4. Nitrogenous fertilizer uptake by guinea grass in several growth flushes; Aproveitamento do nitrogenio do sulfato de amonio ({sup 15} N) pelo capim-coloniao em sucessivos cortes e diferentes epocas de adubacao

    Energy Technology Data Exchange (ETDEWEB)

    Ambrosano, E.J. [Instituto Agronomico de Campinas, SP (Brazil). Secao de Leguminosas; Corsi, M. [Sao Paulo Univ., Piracicaba, SP (Brazil). Escola Superior de Agricultura Luiz de Queiroz. Dept. de Zootecnia; Trivelin, P.C.O. [Centro de Energia Nuclear na Agricultura (CENA), Piracicaba, SP (Brazil); Ambrosano, G.M.B. [Instituto Agronomico de Campinas, SP (Brazil)

    1996-07-01

    Nitrogen recovery was evaluated by the {sup 15} N absorption by guineagrass cv. Tobiata. {sup 15} N fertilizer was applied in February, March, May, June, August and September, in posts containing 5 kg of limed and fertilized soil, under greenhouse conditions in Piracicaba, State of Sao Paulo, Brazil. For each {sup 15} N application three cuttings were performed at approximately 5-7 week interval. The following measurements were taken: consumed water, dry matter yield, nitrogen content, nitrogen in the plant derived form the fertilizers (Ndff), nitrogen recovery (R), and the relation between dry matter yield and nitrogen content. It was also determined the number of vegetative and reproductive tillers and apical meristem elimination. Plant growth was reduced after flowing; highest values of nitrogen recovery in the three cutting were observed for {sup 15} N-fertilizer applied in September and August; highest residual effects, in the second and third cuttings after fertilizers {sup 15} N applications, were observed in September, June and August, reaching 22% in September. (author)

  5. Evaluation of a 15N plot design for estimating plant recovery of fertilizer nitrogen applied to sugar cane Avaliação de um modelo de parcela com fertilizante-15N na determinação do aproveitamento do nitrogênio do fertilizante por cana-de-açúcar

    Directory of Open Access Journals (Sweden)

    P.C.O. Trivelin

    1994-08-01

    Full Text Available Two experiments were conducted on commercial sugar cane fields cropped with the variety SP70-1143, with the objective of evaluating a single row microplot design to determine plant recovery of 15N fertilizer nitrogen. One of them used 15N-aqua ammonia and 15N-urea applied to two linear meter microplots of a ratoon crop (four replicates. The second used one linear meter microplots (three replicates which received 15N-aqua ammonia only. The fertilizers were applied on 15cm deep furrows, located 25cm from both sides of the cane row. One linear meter of ratoon cane, inside and outside of the microplot, and on the same and adjacent rows were harvested twelve months after fertilization. The results indicate the feasibility of using single row segments of ratoon cane with 15N-fertilizer. The main advantage of this microplot design, when compared to the classical 3 contiguous row segments, is that only one third of the labeled fertilizer is needed. In a single row, in order to separate the nitrogen taken up by plants from the fertilizer applied to the row (Nr dff r, from that applied to adjacent rows (Nr dff r+1, and Nr dff r-1, the following should be considered: (a a border segment of 0.5 to 1.0m inside the plot, so that Ndff results from plants harvested in the center of the microplot represent the actual value of fertilizer nitrogen taken up from that applied to the same row, and (b harvest of plants from adjacent rows at equivalent positions to those sampled inside the microplot, to quantify the 15N-fertilizer uptake by outside plants (Nr+1dff r and Nr-1dff r, which is assumed to be the same as non labeled fertilizer applied to adjacent rows (Nr dff r+l and Nr dff r-1 taken up by inside plants. The Ndff total values should be calculated by the equation: Ndff total = Nr dff r + Nr+1dff r + Nr-1dff r.Com o objetivo de avaliar um modelo de parcela, na determinação do aproveitamento pela cana-de-açúcar de fertilizantes nitrogenados-15N, foram

  6. Dry season limnological conditions and basin geology exhibit complex relationships with δ13C and δ15N of carbon sources in four Neotropical floodplains.

    Science.gov (United States)

    Zaia Alves, Gustavo H; Hoeinghaus, David J; Manetta, Gislaine I; Benedito, Evanilde

    2017-01-01

    Studies in freshwater ecosystems are seeking to improve understanding of carbon flow in food webs and stable isotopes have been influential in this work. However, variation in isotopic values of basal production sources could either be an asset or a hindrance depending on study objectives. We assessed the potential for basin geology and local limnological conditions to predict stable carbon and nitrogen isotope values of six carbon sources at multiple locations in four Neotropical floodplain ecosystems (Paraná, Pantanal, Araguaia, and Amazon). Limnological conditions exhibited greater variation within than among systems. δ15N differed among basins for most carbon sources, but δ13C did not (though high within-basin variability for periphyton, phytoplankton and particulate organic carbon was observed). Although δ13C and δ15N values exhibited significant correlations with some limnological factors within and among basins, those relationships differed among carbon sources. Regression trees for both carbon and nitrogen isotopes for all sources depicted complex and in some cases nested relationships, and only very limited similarity was observed among trees for different carbon sources. Although limnological conditions predicted variation in isotope values of carbon sources, we suggest the resulting models were too complex to enable mathematical corrections of source isotope values among sites based on these parameters. The importance of local conditions in determining variation in source isotope values suggest that isotopes may be useful for examining habitat use, dispersal and patch dynamics within heterogeneous floodplain ecosystems, but spatial variability in isotope values needs to be explicitly considered when testing ecosystem models of carbon flow in these systems.

  7. Measurement of the Muon Decay Parameter delta

    CERN Document Server

    Gaponenko, A N; Davydov, Yu I; Depommier, P; Doornbos, J; Faszer, W; Fujiwara, M C; Gagliardi, C A; Gill, D R; Green, P; Gumplinger, P; Hasinoff, M D; Henderson, R S; Hu, J; Jamieson, B; Kitching, P; Koetke, D D; Krushinsky, A A; Lachin, Yu Yu; MacDonald, J A; MacDonald, R P; Marshall, G M; Mathie, E L; Miasoedov, L V; Mischke, R E; Musser, J R; Nord, P M; Nozar, M; Olchanski, K; Olin, A; Openshaw, R; Porcelli, T A; Poutissou, J M; Poutissou, R; Quraan, M A; Rodning, N L; Selivanov, V; Sheffer, G; Shin, B; Sobratee, F; Stanislaus, T D S; Tacik, R; Torokhov, V D; Tribble, R E; Vasilev, M A; Wright, D H

    2004-01-01

    The muon decay parameter delta has been measured by the TWIST collaboration. We find delta = 0.74964 +- 0.00066(stat.) +- 0.00112(syst.), consistent with the Standard Model value of 3/4. This result implies that the product Pmuxi of the muon polarization in pion decay, Pmu, and the muon decay parameter xi falls within the 90% confidence interval 0.9960 < Pmuxi < xi < 1.0040. It also has implications for left-right-symmetric and other extensions of the Standard Model.

  8. O potencial da rotulação metabólica de 15N para a pesquisa de esquizofrenia The potential of 15N metabolic labeling for schizophrenia research

    Directory of Open Access Journals (Sweden)

    Michaela D Filiou

    2012-01-01

    Full Text Available Pesquisas em psiquiatria ainda necessitam de estudos não dirigidos por hipóteses para revelar fundamentos neurobiológicos e biomarcadores moleculares para distúrbios psiquiátricos. Metodologias proteômicas disponibilizam uma série de ferramentas para esses fins. Apresentamos o princípio de rotulação metabólica utilizando 15N para proteômica quantitativa e suas aplicações em modelos animais de fenótipos psiquiátricos com um foco particular em esquizofrenia. Exploramos o potencial de rotulação metabólica por 15N em diferentes tipos de experimentos, bem como suas considerações metodológicas.Psychiatric research is in need of non-hypothesis driven approaches to unravel the neurobiological underpinnings and identify molecular biomarkers for psychiatric disorders. Proteomics methodologies constitute a state-of-the-art toolbox for biomarker discovery in psychiatric research. Here we present the principle of in vivo 15N metabolic labeling for quantitative proteomics experiments and applications of this method in animal models of psychiatric phenotypes, with a particular focus on schizophrenia. Additionally we explore the potential of 15N metabolic labeling in different experimental set-ups as well as methodological considerations of 15N metabolic labeling-based quantification studies.

  9. O potencial da rotulação metabólica de 15N para a pesquisa de esquizofrenia The potential of 15N metabolic labeling for schizophrenia research

    Directory of Open Access Journals (Sweden)

    Michaela D. Filiou

    2013-01-01

    Full Text Available Pesquisas em psiquiatria ainda necessitam de estudos não dirigidos por hipóteses para revelar fundamentos neurobiológicos e biomarcadores moleculares para distúrbios psiquiátricos. Metodologias proteômicas disponibilizam uma série de ferramentas para esses fins. Apresentamos o princípio de rotulação metabólica utilizando 15N para proteômica quantitativa e suas aplicações em modelos animais de fenótipos psiquiátricos com um foco particular em esquizofrenia. Exploramos o potencial de rotulação metabólica por 15N em diferentes tipos de experimentos, bem como suas considerações metodológicas.Psychiatric research is in need of non-hypothesis driven approaches to unravel the neurobiological underpinnings and identify molecular biomarkers for psychiatric disorders. Proteomics methodologies constitute a state-of-the-art toolbox for biomarker discovery in psychiatric research. Here we present the principle of in vivo 15N metabolic labeling for quantitative proteomics experiments and applications of this method in animal models of psychiatric phenotypes, with a particular focus on schizophrenia. Additionally we explore the potential of 15N metabolic labeling in different experimental set-ups as well as methodological considerations of 15N metabolic labeling-based quantification studies.

  10. Tracing sewage water by 15N in a mangrove ecosystem to test its bioremediation ability.

    Science.gov (United States)

    Lambs, Luc; Léopold, Audrey; Zeller, Bernd; Herteman, Mélanie; Fromard, Francois

    2011-10-15

    Mangrove forests could be a simple and effective alternative to conventional sewage treatment, particularly for island communities given its low cost and low maintenance. Due to their high adaptation capacity, these plants are able to tolerate and bioremediate the high levels of nutrients and pollutants found in sewage water. This solution could be applied to small tropical islands with high population density such as Mayotte in the Indian Ocean. This paper reports on a trial by stable isotopic (15)N tracing of such a bioremediation process on pre-treated wastewater near the village of Malamani, in the middle of the large coastal mangrove in the bay near Chirongui. The first results show a boost in the mangrove growth, but a longer period of observation is needed to confirm the beneficial effects, and also to clarify the role of the local crab population, whose engineering activities play an important part in the ecosystem. The exact denitrification process is not yet understood, and the mass balance equation also reveals loss of nitrogen-containing compounds, which needs to be analyzed more closely.

  11. 13C and 15N natural isotope abundance reflects breast cancer cell metabolism

    Science.gov (United States)

    Tea, Illa; Martineau, Estelle; Antheaume, Ingrid; Lalande, Julie; Mauve, Caroline; Gilard, Francoise; Barillé-Nion, Sophie; Blackburn, Anneke C.; Tcherkez, Guillaume

    2016-09-01

    Breast cancer is the most common cancer in women worldwide. Despite the information provided by anatomopathological assessment and molecular markers (such as receptor expression ER, PR, HER2), breast cancer therapies and prognostics depend on the metabolic properties of tumor cells. However, metabolomics have not provided a robust and congruent biomarker yet, likely because individual metabolite contents are insufficient to encapsulate all of the alterations in metabolic fluxes. Here, we took advantage of natural 13C and 15N isotope abundance to show there are isotopic differences between healthy and cancer biopsy tissues or between healthy and malignant cultured cell lines. Isotope mass balance further suggests that these differences are mostly related to lipid metabolism, anaplerosis and urea cycle, three pathways known to be impacted in malignant cells. Our results demonstrate that the isotope signature is a good descriptor of metabolism since it integrates modifications in C partitioning and N excretion altogether. Our present study is thus a starting point to possible clinical applications such as patient screening and biopsy characterization in every cancer that is associated with metabolic changes.

  12. Production of 15N-enriched nitric acid (H15NO3

    Directory of Open Access Journals (Sweden)

    C. R. Sant Ana Filho

    2008-12-01

    Full Text Available Techniques that employ 15N have proved to be an important tool in many areas of the agronomic and biomedical sciences. Nevertheless, their use is limited by methodological difficulties and by the price of compounds in the international market. Nitric compounds (15NO3- have attracted the interest of researchers. However, these compounds are not currently produced in Brazil. Thus, in the present work H15NO3 was obtained from the oxidation of anhydrous 15NH3. The method we used differs from the industrial process in that the absorption tower is replaced with a polytetrafluoroethylene-lined, stainless-steel hydration reactor. The process output was evaluated based on the following parameters: reaction temperature; ratio of reagents; pressure and flow of 15NH3(g through the catalyst (Pt/Rh. The results showed that, at the best conditions (500 ºC; 50 % excess O2; 0.4 MPa; and 3.39 g.min-1 of 15NH3, a conversion percentage (N-15NH3 to N-15NO3- of 62.2 %, an overall nitrogen balance (N-15NH3 + N-15NO3- of 86.8 %, and purity higher than 99 % could be obtained.

  13. Simultaneous quantification of depolymerization and mineralization rates by a novel 15N tracing model

    Science.gov (United States)

    Andresen, Louise C.; Björsne, Anna-Karin; Bodé, Samuel; Klemedtsson, Leif; Boeckx, Pascal; Rütting, Tobias

    2016-09-01

    The depolymerization of soil organic matter, such as proteins and (oligo-)peptides, into monomers (e.g. amino acids) is currently considered to be the rate-limiting step for nitrogen (N) availability in terrestrial ecosystems. The mineralization of free amino acids (FAAs), liberated by the depolymerization of peptides, is an important fraction of the total mineralization of organic N. Hence, the accurate assessment of peptide depolymerization and FAA mineralization rates is important in order to gain a better process-based understanding of the soil N cycle. In this paper, we present an extended numerical 15N tracing model Ntrace, which incorporates the FAA pool and related N processes in order to provide a more robust and simultaneous quantification of depolymerization and gross mineralization rates of FAAs and soil organic N. We discuss analytical and numerical approaches for two forest soils, suggest improvements of the experimental work for future studies, and conclude that (i) when about half of all depolymerized peptide N is directly mineralized, FAA mineralization can be as important a rate-limiting step for total gross N mineralization as peptide depolymerization rate; (ii) gross FAA mineralization and FAA immobilization rates can be used to develop FAA use efficiency (NUEFAA), which can reveal microbial N or carbon (C) limitation.

  14. Effects of 15N application frequency on nitrogen uptake efficiency in citrus trees.

    Science.gov (United States)

    Quiñones, Ana; Bañuls, Josefina; Millo, Eduardo Primo; Legaz, Francisco

    2003-12-01

    Two irrigation systems were used to compare nitrogen uptake efficiency in citrus trees and to evaluate the NO3- runoff in "Navelina" orange trees [Citrus sinensis (L.) Osbeck] on Carrizo citrange rootstock (Citrus sinensis x Poncirus trifoliata Raf.). These were fertilized with 125 g N as labelled K15NO3 and grown outdoors in containers filled with a sand-loamy soil. Two groups of 3 trees received this N dose either in five equally split applications by a flooding irrigation system or in 66 applications by drip. Trees were harvested at the end of the vegetative cycle (December) and the isotopic ratios of 15N/14N were measured in the soil-plant system. The N uptake efficiency of the whole tree was higher with drip irrigation (75%) than with flooding system (64%). In the 0-90 cm soil profile, the N immobilized in the organic fraction was similar for both irrigation methods (around 13 %), whereas the N retained as NO3- was 1% of the N applied under drip and 10% under flooding. In the last case, most of NO3- remained under root system and it could be lost to leaching either by heavy rainfalls or excessive water applications. These results showed that a drip irrigation system was more efficient for improving water use and N uptake from fertilizer, in addition to potentially reduced leaching losses.

  15. Relationship between C2H2 reduction, H2 evolution and 15N2 fixation in root nodules of pea (Pisum sativum)

    DEFF Research Database (Denmark)

    Skøt, Leif

    1983-01-01

    The quantitative relationship between C2H2 reduction, H2 evolution and 15N2 fixation was investigated in excised root nodules from pea plants (Pisum sativum L. cv. Bodil) grown under controlled conditions. The C2H2/N2 conversion factor varied from 3.31 to 5.12 between the 32nd and the 67th day...... after planting. After correction for H2 evolution in air, the factor (C2H2-H2)/N2 decreased to values near the theoretical value 3, or in one case to a value significantly (P H2 production but used...... for N2 reduction, is often stated as the relative efficiency (1-H2/C2H2). This factor varied significantly (P H2 and N2, expressed as the H2/N2 ratio, was independent of plant age, however. This discrepancy and the observation...

  16. A global analysis of human habitation on river deltas

    Science.gov (United States)

    Edmonds, Douglas; Caldwell, Rebecca; Baumgardner, Sarah; Paola, Chris; Roy, Samapriya; Nelson, Amelia; Nienhuis, Jaap

    2017-04-01

    River deltas are ideal sites for human habitation because of their fertile floodplains, easy access to the ocean, and abundant land. But anthropogenic and natural processes are causing deltas to sink, which increases the probability of coastal flooding and human exposure to risk. The full extent of the risk posed to humans is unclear because the number of people living on river deltas is unknown. Towards this end we mapped the locations and areas of all deltas in the world (n= 1813). Using Google Earth we identified all river mouths (≥ 50 m wide) on marine coastlines that are also connected to an upstream catchment. Rivers that split into two or more active or relict distributary channels, end in a depositional protrusion from the shoreline, or do both, are defined as deltas. The depositional protrusion and distributary channel network define the geomorphic area of each delta. We mark the position of the delta apex at the first bifurcation, or for a single channel delta at the intersection of the regional shoreline and the main channel. We mark three lateral extents, one on either side of the main channel at the maximum displacement of the depositional protrusion or the distributary network, and one on the most basinward position of the delta. We define delta area as the convex hull around these extent points and the delta apex. For each delta area polygon we extract elevation from the Shuttle Radar Topography Mission dataset and population count in years 2000, 2005, 2010, 2015, and 2020 from Gridded Population of the World, version 4. In total, deltas cover 0.56% of the total area of the world yet contain 4.1% of the world's population. The population on deltas has grown from 237 million in 2000 to projected values of 322 million in 2020. Deltaic population is growing at 1.59% per year, which outpaces the world growth rate of 1.11%. Additionally, population density is increasing with time from 322 people per km2 in year 2000 to projected values of 422 people per

  17. QCD in the {delta}-regime

    Energy Technology Data Exchange (ETDEWEB)

    Bietenholz, W. [Universidad Nacional Autonoma de Mexico, Mexico City (Mexico). Inst. de Ciencias Nucleares; Cundy, N. [Seoul National Univ. (Korea, Republic of). Lattice Gauge Theory Research Center; Goeckeler, M. [Regensburg Univ. (Germany). Inst. fuer Theoretische Physik; Horsley, R.; Zanotti, J.M. [Edinburgh Univ. (United Kingdom). School of Physics; Nakamura, Y. [Tsukuba Univ., Ibaraki (Japan). Center for Computational Sciences; Pleiter, D. [Deutsches Elektronen-Synchrotron (DESY), Zeuthen (Germany); Rakow, P.E.L. [Liverpool Univ. (United Kingdom). Theoretical Physics Div.; Schierholz, G. [Regensburg Univ. (Germany). Inst. fuer Theoretische Physik; Deutsches Elektronen-Synchrotron (DESY), Hamburg (Germany)

    2011-03-15

    The {delta}-regime of QCD is characterised by light quarks in a small spatial box, but a large extent in (Euclidean) time. In this setting a specific variant of chiral perturbation theory - the {delta}-expansion - applies, based on a quantum mechanical treatment of the quasi onedimensional system. In particular, for vanishing quark masses one obtains a residual pion mass M{sup R}{sub {pi}}, which has been computed to the third order in the {delta}-expansion. A comparison with numerical measurements of this residual mass allows for a new determination of some Low Energy Constants, which appear in the chiral Lagrangian. We first review the attempts to simulate 2-flavour QCD directly in the {delta}-regime. This is very tedious, but results compatible with the predictions for M{sup R}{sub {pi}} have been obtained. Then we show that an extrapolation of pion masses measured in a larger volume towards the {delta}-regime leads to good agreement with the theoretical predictions. From those results, we also extract a value for the (controversial) sub-leading Low Energy Constant anti l{sub 3}. (orig.)

  18. Flood forests of the inner Niger delta, mali; past, present, and future

    NARCIS (Netherlands)

    Beintema, A.J.; Fofana, B.; Faye, A.; Huiskes, H.P.J.

    2005-01-01

    Flood forests have a special place in the Inner Niger Delta, Mali. They have a great economic value for the local populations, and are hotspots of biodiversity in the delta. This report reviews the status of all flood forests in the Inner Niger Delta, Mali, that are presently known, or have been kno

  19. The Niger Delta Crisis

    African Journals Online (AJOL)

    chifaou.amzat

    2013-09-28

    Sep 28, 2013 ... lions de barils par jour à environ 1 million au plus fort de la crise du Delta ... (JTF) between 13 May 2009 and 4 October 2009 (the deadline for embrac- ..... He had just ended his welcome address as the occasion's chairman.

  20. Glacial–interglacial dynamics of Antarctic firn columns: comparison between simulations and ice core air-δ15N measurements

    Directory of Open Access Journals (Sweden)

    E. Capron

    2013-05-01

    Full Text Available Correct estimation of the firn lock-in depth is essential for correctly linking gas and ice chronologies in ice core studies. Here, two approaches to constrain the firn depth evolution in Antarctica are presented over the last deglaciation: outputs of a firn densification model, and measurements of δ15N of N2 in air trapped in ice core, assuming that δ15N is only affected by gravitational fractionation in the firn column. Since the firn densification process is largely governed by surface temperature and accumulation rate, we have investigated four ice cores drilled in coastal (Berkner Island, BI, and James Ross Island, JRI and semi-coastal (TALDICE and EPICA Dronning Maud Land, EDML Antarctic regions. Combined with available ice core air-δ15N measurements from the EPICA Dome C (EDC site, the studied regions encompass a large range of surface accumulation rates and temperature conditions. Our δ15N profiles reveal a heterogeneous response of the firn structure to glacial–interglacial climatic changes. While firn densification simulations correctly predict TALDICE δ15N variations, they systematically fail to capture the large millennial-scale δ15N variations measured at BI and the δ15N glacial levels measured at JRI and EDML – a mismatch previously reported for central East Antarctic ice cores. New constraints of the EDML gas–ice depth offset during the Laschamp event (~41 ka and the last deglaciation do not favour the hypothesis of a large convective zone within the firn as the explanation of the glacial firn model–δ15N data mismatch for this site. While we could not conduct an in-depth study of the influence of impurities in snow for firnification from the existing datasets, our detailed comparison between the δ15N profiles and firn model simulations under different temperature and accumulation rate scenarios suggests that the role of accumulation rate may have been underestimated in the current description of firnification

  1. STELLAR ORIGINS OF EXTREMELY {sup 13}C- AND {sup 15}N-ENRICHED PRESOLAR SIC GRAINS: NOVAE OR SUPERNOVAE?

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Nan; Nittler, Larry R.; Alexander, Conel M. O’D.; Wang, Jianhua [Department of Terrestrial Magnetism, Carnegie Institution for Science, Washington, DC 20015 (United States); Pignatari, Marco [E.A. Milne Centre for Astrophysics, Department of Physics and Mathematics, University of Hull, HU6 7RX (United Kingdom); José, Jordi [Department de Fisica, EUETIB, Universitat Politécnica de Catalunya, E-08036 Barcelona (Spain); Nguyen, Ann, E-mail: nliu@carnegiescience.edu [Robert M. Walker Laboratory for Space Science, Astromaterials Research and Exploration Science Directorate, NASA Johnson Space Center, Houston, TX 77058 (United States)

    2016-04-01

    Extreme excesses of {sup 13}C ({sup 12}C/{sup 13}C < 10) and {sup 15}N ({sup 14}N/{sup 15}N < 20) in rare presolar SiC grains have been considered diagnostic of an origin in classical novae, though an origin in core collapse supernovae (CCSNe) has also been proposed. We report C, N, and Si isotope data for 14 submicron- to micron-sized {sup 13}C- and {sup 15}N-enriched presolar SiC grains ({sup 12}C/{sup 13}C < 16 and {sup 14}N/{sup 15}N < ∼100) from Murchison, and their correlated Mg–Al, S, and Ca–Ti isotope data when available. These grains are enriched in {sup 13}C and {sup 15}N, but with quite diverse Si isotopic signatures. Four grains with {sup 29,30}Si excesses similar to those of type C SiC grains likely came from CCSNe, which experienced explosive H burning occurred during explosions. The independent coexistence of proton- and neutron-capture isotopic signatures in these grains strongly supports heterogeneous H ingestion into the He shell in pre-supernovae. Two of the seven putative nova grains with {sup 30}Si excesses and {sup 29}Si depletions show lower-than-solar {sup 34}S/{sup 32}S ratios that cannot be explained by classical nova nucleosynthetic models. We discuss these signatures within the CCSN scenario. For the remaining five putative nova grains, both nova and supernova origins are viable because explosive H burning in the two stellar sites could result in quite similar proton-capture isotopic signatures. Three of the grains are sub-type AB grains that are also {sup 13}C enriched, but have a range of higher {sup 14}N/{sup 15}N. We found that {sup 15}N-enriched AB grains (∼50 < {sup 14}N/{sup 15}N < ∼100) have distinctive isotopic signatures compared to putative nova grains, such as higher {sup 14}N/{sup 15}N, lower {sup 26}Al/{sup 27}Al, and lack of {sup 30}Si excess, indicating weaker proton-capture nucleosynthetic environments.

  2. Liquefaction potential of Nile delta, Egypt

    Science.gov (United States)

    Fergany, Elsayed; Omar, Khaled

    2017-06-01

    Understanding how sedimentary basins respond to seismic-wave energy generated by earthquake events is a significant concern for seismic-hazard estimation and risk analysis. The main goal of this study is assessing the vulnerability index, Kg, as an indicator for liquefaction potential sites in the Nile delta basin based on the microtremor measurements. Horizontal to Vertical spectral ratio analyses (HVSR) of ambient noise data, which was conducted in 2006 at 120 sites covering the Nile delta from south to north were reprocessed using Geopsy software. HVSR factors of amplification, A, and fundamental frequency, F, were calculated and Kg was estimated for each measurement. The Kg value varies widely from south toward north delta and the potential liquefaction places were estimated. The higher vulnerability indices are associated with sites located in southern part of the Nile delta and close to the branches of Nile River. The HVSR factors were correlated with geologic setting of the Nile delta and show good correlations with the sediment thickness and subsurface stratigraphic boundaries. However, we note that sites located in areas that have greatest percentage of sand also yielded relatively high Kg values with respect to sites in areas where clay is abundant. We concluded that any earthquake with ground acceleration more than 50 gal at hard rock can cause a perceived deformation of sandy sediments and liquefaction can take place in the weak zones of Kg ≥ 20. The worst potential liquefaction zones (Kg > 30) are frequently joined to the Damietta and Rosetta Nile River branches and south Delta where relatively coarser sand exists. The HVSR technique is a very sensitive tool for lithological stratigraphy variations in two dimensions and varying liquefaction susceptibility.

  3. Stellar Origins of Extremely $^{\\text{13}}C$- and $^{15}N$-enriched Presolar SiC Grains: Novae or Supernovae?

    CERN Document Server

    Liu, Nan; Alexander, Conel M O'D; Wang, Jianhuan; Pignatari, Marco; Jose, Jordi; Nguyen, Ann

    2016-01-01

    Extreme excesses of $^{13}C$ ($^{12}C$/$^{13}C$<10) and $^{15}N$ ($^{14}N$/$^{15}N$<20) in rare presolar SiC grains have been considered diagnostic of an origin in classical novae, though an origin in core collapse supernovae (CCSNe) has also been proposed. We report C, N, and Si isotope data for 14 submicron- to micron-sized $^{13}C$- and $^{15}N$-enriched presolar SiC grains ($^{12}C$/$^{13}C$<16 and $^{14}N$/$^{15}N$<~100) from Murchison, and their correlated Mg-Al, S, and Ca-Ti isotope data when available. These grains are enriched in $^{13}C$ and $^{15}N$, but with quite diverse Si isotopic signatures. Four grains with $^{29,30}Si$ excesses similar to those of type C SiC grains likely came from CCSNe, which experienced explosive H burning occurred during explosions. The independent coexistence of proton- and neutron-capture isotopic signatures in these grains strongly supports heterogeneous H ingestion into the He shell in pre-supernovae. Two of the seven putative nova grains with $^{30}Si$ e...

  4. Evaluation of a {sup 15} N plot design for estimating plant recovery of fertilizer nitrogen applied to sugar cane

    Energy Technology Data Exchange (ETDEWEB)

    Trivelin, P.C.O.; Cabezas, W.A.R.L.; Victoria, R.L.; Reichardt, K. [Centro de Energia Nuclear na Agricultura (CENA), Piracicaba, SP (Brazil)

    1994-05-01

    Two experiments were conducted on commercial sugar cene fields cropped with the variety SP70-1143, with the objective of evaluating a single row microplot design to determine plant recovery of {sup 15} N fertilizer nitrogen. One of them used {sup 15} N-aqua ammonia and {sup 15} N-urea applied to two linear meter microplots of a ratoon crop (four replicates.) The second used one linear meter microplots (three replicates) which received {sup 15} N-aqua ammonia only. The fertilizers were applied on 15cm deep furrows, located 25 cm from both sides of the cane row. One linear meter of ratoon cane, inside and outside of the microplot, and on the same and adjacent rows were harvested twelve months after fertilization. The results indicate the feasibility of using single row regments of ratoon cane with {sup 15} N-fertilizer. The main advantages of this microplot design, when compared to the classical 3 contiguous row segments, is that only one third of the labeled fertilizer is needed. (author). 25 refs, 3 figs, 5 tabs.

  5. Probing site-specific 13C/15N-isotope enrichment of spider silk with liquid-state NMR spectroscopy.

    Science.gov (United States)

    Shi, Xiangyan; Yarger, Jeffery L; Holland, Gregory P

    2013-05-01

    Solid-state nuclear magnetic resonance (NMR) has been extensively used to elucidate spider silk protein structure and dynamics. In many of these studies, site-specific isotope enrichment is critical for designing particular NMR methods for silk structure determination. The commonly used isotope analysis techniques, isotope-ratio mass spectroscopy and liquid/gas chromatography-mass spectroscopy, are typically not capable of providing the site-specific isotope information for many systems because an appropriate sample derivatization method is not available. In contrast, NMR does not require any sample derivatization or separation prior to analysis. In this article, conventional liquid-state (1)H NMR was implemented to evaluate incorporation of (13)C/(15)N-labeled amino acids in hydrolyzed spider dragline silk. To determine site-specific (13)C and (15)N isotope enrichments, an analysis method was developed to fit the (1)H-(13)C and (1)H-(15)N J-splitting (J CH and J NH) (1)H NMR peak patterns of hydrolyzed silk fiber. This is demonstrated for Nephila clavipes spiders, where [U-(13)C3,(15)N]-Ala and [1-(13)C,(15)N]-Gly were dissolved in their water supplies. Overall, contents for Ala and Gly isotopomers are extracted for these silk samples. The current methodology can be applied to many fields where site-specific tracking of isotopes is of interest.

  6. Evaluation of N sub 2 fixation by applying sup 15 N labeled plant material and ammonium sulfate

    Energy Technology Data Exchange (ETDEWEB)

    Chiu, C.Y.; Yoshida, T.

    1990-06-01

    Effect of different {sup 15}N labeled sources on the estimation of N{sub 2} fixation was investigated. The combination of {sup 15}N labeled ammonium sulfate, {sup 15}N labeled plant material, and {sup 15}N labeled ammonium sulfate with unlabeled plant material, was examined in pot experiments. Two cultivars of soybean (Glycine max) and one of mungbean (Vigna radiata) were used. No significant difference was observed among the treatments for the estimation of N{sub 2} fixation. This was due to the homogeneity and stability of the {sup 15}N abundance in soil which resulted in a similar N uptake from the soil by the N{sub 2} fixing and reference crops. The plant yield, total N uptake and amount of N{sub 2} fixed were higher in the Yellow Soil than in the Andosol. The amount of N{sub 2} fixed was strongly influenced by the plant growth and consequently it affected the plant yield. The slow decomposition of plant material in the Andosol resulted in a low yield in both the N{sub 2} fixing and reference crops. Thus, the artificial decrease of the available N content in soil, by application of plant material, did not stimulate N{sub 2} fixation but suppressed plant growth and N{sub 2} fixation.

  7. Nitrate removal in stream ecosystems measured by 15N addition experiments: Denitrification

    Science.gov (United States)

    Mulholland, P.J.; Hall, R.O.; Sobota, D.J.; Dodds, W.K.; Findlay, S.E.G.; Grimm, N. B.; Hamilton, S.K.; McDowell, W.H.; O'Brien, J. M.; Tank, J.L.; Ashkenas, L.R.; Cooper, L.W.; Dahm, Clifford N.; Gregory, S.V.; Johnson, S.L.; Meyer, J.L.; Peterson, B.J.; Poole, G.C.; Valett, H.M.; Webster, J.R.; Arango, C.P.; Beaulieu, J.J.; Bernot, M.J.; Burgin, A.J.; Crenshaw, C.L.; Helton, A.M.; Johnson, L.T.; Niederlehner, B.R.; Potter, J.D.; Sheibley, R.W.; Thomasn, S.M.

    2009-01-01

    We measured denitrification rates using a field 15N-NO- 3 tracer-addition approach in a large, cross-site study of nitrate uptake in reference, agricultural, and suburban-urban streams. We measured denitrification rates in 49 of 72 streams studied. Uptake length due to denitrification (SWden) ranged from 89 m to 184 km (median of 9050 m) and there were no significant differences among regions or land-use categories, likely because of the wide range of conditions within each region and land use. N2 production rates far exceeded N2O production rates in all streams. The fraction of total NO-3 removal from water due to denitrification ranged from 0.5% to 100% among streams (median of 16%), and was related to NHz 4 concentration and ecosystem respiration rate (ER). Multivariate approaches showed that the most important factors controlling SWden were specific discharge (discharge / width) and NO-3 concentration (positive effects), and ER and transient storage zones (negative effects). The relationship between areal denitrification rate (Uden) and NO- 3 concentration indicated a partial saturation effect. A power function with an exponent of 0.5 described this relationship better than a Michaelis-Menten equation. Although Uden increased with increasing NO- 3 concentration, the efficiency of NO-3 removal from water via denitrification declined, resulting in a smaller proportion of streamwater NO-3 load removed over a given length of stream. Regional differences in stream denitrification rates were small relative to the proximate factors of NO-3 concentration and ecosystem respiration rate, and land use was an important but indirect control on denitrification in streams, primarily via its effect on NO-3 concentration. ?? 2009.

  8. delta13C and delta18O trends across overstory environments in whole foliage and cellulose of three Pinus species.

    Science.gov (United States)

    Powers, Matthew D; Pregitzer, Kurt S; Palik, Brian J

    2008-09-01

    Stable isotope ratios of carbon (delta(13)C) and oxygen (delta(18)O) are increasingly used to investigate environmental influences on plant physiology. Cellulose is often isolated for isotopic studies, but some authors have questioned the value of this process. We studied trends in delta(13)C and delta(18)O of whole foliage and holocellulose from seedlings of three Pinus species across three overstory environments to evaluate the benefits of holocellulose extraction in the context of a traditional ecological experiment. Both tissue types showed increasing delta(13)C from closed-canopy controls to thinned plots to 0.3 ha canopy gaps, and no change in delta(18)O between overstory environments. delta(13)C of P. resinosa and P. strobus was greater than delta(13)C of P. banksiana in whole foliage and holocellulose samples, and there were no differences in delta(18)O associated with species in either tissue type. Our results suggest whole foliage and holocellulose provide similar information about isotopic trends across broad environmental gradients and between species, but holocellulose may be better suited for studying differences in stable isotope composition between multiple species across several treatments.

  9. 15N-glycine absorption in the colon of the short bowel rats%短肠大鼠结肠对15N-甘氨酸的吸收研究

    Institute of Scientific and Technical Information of China (English)

    靳大勇; 许剑民; 吴海福; 吴肇汉; 夏立均; 王锦华; 胡耀明

    2001-01-01

    Objective To investigate 15N-glycine absorption in the colon of the short bowel rats.Methods Rats undergoing resection of 80% small intestine and were treated by enteral nutrition for 21 days.The concentration of 15N-glycine in perfusate samples was measured by the technique of HPLC.The atom percent enrichment of 15N-glycine in blood plasma was measured by the technique of isotopic dilution method.Results After 3 hours,the colonic water absorption was 1±0.5 ml,15N-glycine absorption was zero,and the atom percent enrichment was near zero in normal group,vs.(2.6±0.82) ml (P<0.05),(4.39±1.2)% (P<0.01),and (0.614±0.517)% (P<0.01) in short bowel rats,respectively.The mucosal thickness,villous height and surface area of the colon in enteral nutrition group were greater than that in controls (P<0.01).Conclusion The short bowel rats had significant colonic amino acids and water absorption adaptation,though not enough to fulfil the need of the body.%目的探讨短肠大鼠的结肠对氨基酸代偿吸收能力。方法切除80%小肠的短肠大鼠,经肠喂养21天后,测定结肠对15N-甘氨酸的吸收率和血15N-甘氨酸丰度及形态学改变。结果正常大鼠3h水吸收为(1±0.5)ml,对15N-甘氨酸无吸收,血中15N-甘氨酸丰度为零。短肠大鼠3h水吸收为(2.6±0.82)ml (P<0.05),15N-甘氨酸为(4.39±1.2)% (P<0.01),血中15N-甘氨酸丰度为(0.614±0.517)% (P<0.01)。形态学检测显示: 喂养组与对照组相比结肠直径差异有显著意义(P<0.05),而结肠壁厚度、粘膜厚度、皱襞高度和皱襞表面积差异有极显著的意义(P<0.01)。结论短肠大鼠结肠对水和15N-甘氨酸有一定代偿性吸收,组织形态学也有一定程度的代偿。

  10. Carbon (δ13C) and Nitrogen (δ15N) Stable Isotope Signatures in Bat Fur Indicate Swarming Sites Have Catchment Areas for Bats from Different Summering Areas.

    Science.gov (United States)

    Segers, Jordi L; Broders, Hugh G

    2015-01-01

    Migratory patterns of bats are not well understood and traditional methods to study this, like capture-mark-recapture, may not provide enough detail unless there are many records. Stable isotope profiles of many animal species have been used to make inferences about migration. Each year Myotis lucifugus and M. septentrionalis migrate from summering roosts to swarming caves and mines in the fall, but the pattern of movement between them is not well understood. In this study, fur δ13C and δ15N values of 305 M. lucifugus and 200 M. septentrionalis were analyzed to make inferences about migration patterns between summering areas and swarming sites in Nova Scotia, Canada. We expected that there would be greater variability in δ13C and δ15N among individuals at swarming sites because it was believed that these sites are used by individuals originating from many summering areas. There was extensive overlap in the standard ellipse area, corrected for small sample sizes (SEAc), of bats at swarming sites and much less overlap in SEAc among groups sampled at summering areas. Meaningful inference could not be made on M. septentrionalis because their low variation in SEAc may have been the result of sampling only 3 summering areas. However, for M. lucifugus, swarming sites had larger SEAc than summering areas and predictive discriminant analysis assigned swarming bats to multiple summering areas, supporting the contention that swarming bats are mixed aggregations of bats from several summering areas. Together, these data support the contention that swarming sites have catchment areas for bats from multiple summering areas and it is likely that the catchment areas for swarming sites overlap. These data suggest that δ13C and δ15N profiling of bat fur offer some potential to make inferences about regional migration in bats.

  11. Longitudinal spin asymmetries and $\\Delta G$ at COMPASS

    CERN Document Server

    Le Goff, Jean-Marc

    2008-01-01

    The spin structure $g_{1}$ of the deuteron has been measured by COMPASS with unprecedented accuracy at low $x$, providing much more reliable values for the first moment $\\Gamma_{1}$ and for the quark spin contribution $\\Delta\\Sigma$. Difference-charge semi-inclusive asymmetries have been measured and seem to favor a flavor asymmetric polarized sea. The gluon polarization has been measured in the open-charm and high-$p_{t}$ channels. Large values of $\\Delta G$ are now unlikely.

  12. Recovery and Leaching of 15N-Labeled Coated Urea in a Lysimeter System in the North China Plain

    Institute of Scientific and Technical Information of China (English)

    LI Gui-Hua; ZHAO Lin-Ping; ZHANG Shu-Xiang; Y. HOSEN; K. YAGI3

    2011-01-01

    The effectiveness of polyolefin-coated urea (Meister-5 and Meister-10; CU) in a wheat (Triticum aestivum L.)-maize (Zea mays L.) rotation system was studied in lysimeter plots located in the North China Plain for three consecutive maize- wheat-maize cropping seasons.An isotopic method was used to compare the fate of CU to that of non-coated urea (NCU),and N application rates of 0,100,150 and 225 kg N ha-1 were evaluated.The results showed that the nitrogen use efficiency (15NUE) of CU was 13.3% 21.4% greater than that of NCU for the first crop.Alternatively,when the difference method was applied (apparent NUE),no significant variations were observed among treatments in all three seasons.Although inorganic N leached from the 1.3 m layer was less than 1% of the total applied N,unidentified losses of 15N (losses of 15N =15N applied as fertilizer - 15N absorbed by crops - 15N remaining in the 0-0.2 m layer 15N leached from the 1.3 m layer)in CU-treated plots were 24.2%-26.5% lower than those of NCU-treated plots.The nitrate concentration in the 0-1.3 m layer of CU plots at the end of the experiment was 53% lower than that of NCU-treated plots.Thus,CU increased crop N uptake from fertilizer and reduced unidentified losses of applied N,which can reduce the risk of groundwater pollution.

  13. A 15N-Labeling Study of the Capture of Deep Soil Nitrate from Different Plant Systems

    Institute of Scientific and Technical Information of China (English)

    YANG Zhi-xin; WANG Jue; DI Hong-jie; ZHANG Li-juan; JU Xiao-tang

    2014-01-01

    The objective of this study was to determine the efifciency of different plant systems in capturing deep soil nitrate (NO3-) to reduce NO3-leaching in a ifeld plot experiment using 15N labelling. The study was conducted on a calcareous alluvial soil on the North China Plains and the plant systems evaluated included alfalfa (Medicago sativa), American black poplar (Populus nigra) and cocksfoot (Dactylis). 15N-labelled N fertilizer was injected to 90 cm depth to determine the recovery of 15N by the plants. With conventional water and nutrient management, the total recovery of 15N-labeled NO3--N was 23.4% by alfalfa after two consecutive growth years. The recovery was signiifcantly higher than those by American black poplar (12.3%) and cocksfoot (11.4%). The highest proportion of soil residual 15N from the labeled fertilizer N (%Ndff) was detected around 90 cm soil depth at the time of the 1st year harvest and at 110-130 cm soil depth at time of the 2nd year harvest. Soil%Ndff in 0-80 cm depth was signiifcantly higher in the alfalfa treatment than those in all the other treatments. The soil%Ndff below 100 cm depth was much lower in the alfalfa than those in all the other treatments. These results indicated that 15N leaching losses in the alfalfa treatment were signiifcantly lower than by those in the black poplar and cocksfoot treatments, due to the higher root density located in nitrate labeling zone of soil proifle. In conclusion, alfalfa may be used as a plant to capture deep soil NO3-left from previous crops to reduce NO3-leaching in high intensity crop cultivation systems of North China Plain.

  14. [Effect of fertilization depth on 15N-urea absorption, utilization and loss in dwarf apple trees].

    Science.gov (United States)

    Ding, Ning; Chen, Qian; Xu, Hai-gang; Ji, Meng-meng; Jiang, Han; Jiang, Yuan-mao

    2015-03-01

    Five-year-old 'Fuji'3/M26/M. hupehensis Rehd. seedlings were treated by 15N tracer to study the effects of fertilization depth (0, 20 and 40 cm) on 15N-urea absorption, distribution, utilization and loss in soil. The results showed that the plant leaf area, chlorophyll content and total N of apple leaves in 20 cm treatment were obviously higher than 0 cm and 40 cm treatments. The 15N derived from fertilizer (Ndff) in different organs of apple plant under different depths were significantly different, and the Ndff was the highest in roots at the full-bloom stage, and then in perennial branches. During the shoot rapid-growing and flower bud differentiation stage, the Ndff of new organs higher than that of the storage organs, and the Ndff of different organs were high level at fruit rapid-expanding stage, and the Ndff of fruit was the highest. The distribution ratio of 15N at fruit maturity stage was significantly different under fertilization depths, and that of the vegetative and repro- ductive organs of 20 cm treatment were obviously higher than 0 cm and 40 cm treatments, but that of the storage organs of 20 cm treatment was lower than 0 cm and 40 cm treatments. At fruit maturity stage, 15N utilization rate of apple plant of 20 cm treatment was 24.0%, which was obviously higher than 0 cm (14.1%) and 40 cm (7.6%) treatments, and 15N loss rate was 54.0%, which was obviously lower than 0 cm (67.8%) and 40 cm (63.5%) treatments. With the increase of fertilization depths, the N residue in soil increased sharply.

  15. Direct measurement of the 15N(p,gamma)16O total cross section at novae energies

    CERN Document Server

    Bemmerer, D; Bonetti, R; Broggini, C; Confortola, F; Corvisiero, P; Costantini, H; Elekes, Z; Formicola, A; Fülöp, Z; Gervino, G; Guglielmetti, A; Gustavino, C; Gyurky, Gy; Junker, M; Limata, B; Marta, M; Menegazzo, R; Prati, P; Roca, V; Rolfs, C; Alvarez, C Rossi; Somorjai, E; Straniero, O

    2009-01-01

    The 15N(p,gamma)16O reaction controls the passage of nucleosynthetic material from the first to the second carbon-nitrogen-oxygen (CNO) cycle. A direct measurement of the total 15N(p,gamma)16O cross section at energies corresponding to hydrogen burning in novae is presented here. Data have been taken at 90-230 keV center-of-mass energy using a windowless gas target filled with nitrogen of natural isotopic composition and a bismuth germanate summing detector. The cross section is found to be a factor two lower than previously believed.

  16. Glacial-interglacial dynamics of Antarctic firn columns: comparison between simulations and ice core air-δ15N measurements

    Directory of Open Access Journals (Sweden)

    R. Mulvaney

    2012-12-01

    Full Text Available Correct estimate of the firn lock-in depth is essential for correctly linking gas and ice chronologies in ice cores studies. Here, two approaches to constrain the firn depth evolution in Antarctica are presented over the last deglaciation: output of a firn densification model and measurements of δ15N of N2 in air trapped in ice core. Since the firn densification process is largely governed by surface temperature and accumulation rate, we have investigated four ice cores drilled in coastal (Berkner Island, BI, and James Ross Island, JRI and semi coastal (TALDICE and EPICA Dronning Maud Land, EDML Antarctic regions. Combined with available δ15N measurements performed from the EPICA Dome C (EDC site, the studied regions encompass a large range of surface accumulation rate and temperature conditions. While firn densification simulations are able to correctly represent most of the δ15N trends over the last deglaciation measured in the EDC, BI, TALDICE and EDML ice cores, they systematically fail to capture BI and EDML δ15N glacial levels, a mismatch previously seen for Central East Antarctic ice cores. Using empirical constraints of the EDML gas-ice depth offset during the Laschamp event (~ 41 ka, we can rule out the existence of a large convective zone as the explanation of the glacial firn model-δ15N data mismatch for this site. The good match between modelled and measured δ15N at TALDICE as well as the lack of any clear correlation between insoluble dust concentration in snow and δ15N records in the different ice cores suggest that past changes in loads of impurities are not the only main driver of glacial-interglacial changes in firn lock-in depth. We conclude that firn densification dynamics may instead be driven mostly by accumulation rate changes. The mismatch between modelled and measured δ15N may be due to inaccurate reconstruction of past accumulation rate or underestimated influence of accumulation rate in firnification models.

  17. Glacial–interglacial dynamics of Antarctic firn columns: comparison between simulations and ice core air-δ15N measurements

    OpenAIRE

    2013-01-01

    Correct estimation of the firn lock-in depth is essential for correctly linking gas and ice chronologies in ice core studies. Here, two approaches to constrain the firn depth evolution in Antarctica are presented over the last deglaciation: outputs of a firn densification model, and measurements of δ15N of N2 in air trapped in ice core, assuming that δ15N is only affected by gravitational fractionation in the firn column. Since the firn densification process is largely governed by...

  18. Recovery of {sup 15}N-urea in soil-plant system of tanzania grass pasture; Recuperacao de {sup 15}N-ureia no sistema solo-planta de pastagem de capim-Tanzania

    Energy Technology Data Exchange (ETDEWEB)

    Martha Junior, Geraldo Bueno; Vilela, Lourival [EMBRAPA Cerrados, Planaltina, DF (Brazil)], e-mail: gbmartha@cpac.embrapa.br; Corsi, Moacyr [Universidade de Sao Paulo (ESALQ/USP), Piracicaba, SP (Brazil). Escola Superior de Agricultura Luiz de Queiroz. Dept. de Zootecnica], e-mail: moa@esalq.usp.br; Trivelin, Paulo Cesar Ocheuze [Centro de Energia Nuclear na Agricultura (CENA/USP), Piracicaba, SP (Brazil). Lab. de Isotopos Estaveis], e-mail: pcotrive@cena.usp.br

    2009-01-15

    The economic attractiveness and negative environmental impact of nitrogen (N) fertilization in pastures depend on the N use efficiency in the soil-plant system. However, the recovery of urea-{sup 15}N by Panicum maximum cv. Tanzania pastures, one of the most widely used forage species in intensified pastoral systems, is still unknown. This experiment was conducted in a randomized complete block design with four treatments (0, 40, 80 and 120 kg ha-1 of N-urea) and three replications, to determine the recovery of {sup 15}N urea by Tanzania grass. Forage production, total N content and N yield were not affected by fertilization (p > 0.05), reflecting the high losses of applied N under the experimental conditions. The recovery of {sup 15}N urea (% of applied N) in forage and roots was not affected by fertilization levels (p > 0.05), but decreased exponentially in the soil and soil-plant system (p < 0.05) with increasing urea doses. The amount of {sup 15}N (kg ha{sup -1}) in forage and roots (15 to 30 cm) increased with increasing urea doses (p < 0.05). (author)

  19. Total N content and δ15N signatures in moss tissue for indicating varying atmospheric nitrogen deposition in Guizhou Province, China

    Science.gov (United States)

    Qu, Linglu; Xiao, Huayun; Guan, Hui; Zhang, Zhongyi; Xu, Yu

    2016-10-01

    Unsurprisingly, the amount of reactive nitrogen circulating annually on land has been doubled because of increasing anthropogenic activities. Exceedingly large amounts of reactive nitrogen (Nr) are likely to disrupt N dynamics and negatively impact the environment and human health. Guizhou Province, a major energy-producing province in southwest China, is suffering from serious long-term acid deposition. However, little work has been done to quantify the levels of atmospheric N deposition in this province, in which some ecologically vulnerable areas have resulted from rocky desertification. In this study, tissue N contents and δ15N signatures in 109 epilithic mosses were analyzed by the ordinary kriging (OK) interpolation technique to determine atmospheric N deposition. Moss N content (1.36-2.65%) showed a significant decrease from west to east, indicating that the spatial variance of TN deposition was the same as that of moss N content, with an average of 27.74 kg N ha-1 yr-1. Moss δ15N ranged from -5.89‰ to -0.72‰ and showed an opposite spatial variance compared with moss N contents. Negative δ15N indicated that the main sources for N deposition were urban sewage and agricultural NH3. According to Moss δ15N values, it could be concluded that NH4+-N and NO3--N were the main components of wet deposition, accounting for 52% and 44% of TN, respectively. The deposition fluxes were 14.49 kg N ha-1 yr-1 and 12.16 kg N ha-1 yr-1, respectively. Although the emission flux of NO3--N far exceeded that of NH4+-N, the amount of NH4+-N deposited on land was larger than that of NO3--N. N deposition in 99.6% of the province exceeded the critical load for terrestrial ecosystems. High N deposition is the main environmental problem facing Guizhou Province, and recommendations regarding regulatory strategies for mitigating atmospheric N pollution are urgently needed.

  20. Estimation of internal and external nitrogen for corals with a long-term 15N-labelling experiment and subsequent model calculations

    Science.gov (United States)

    Tanaka, Yasuaki; Grottoli, Andréa; Matsui, Yohei; Suzuki, Atsushi; Sakai, Kazuhiko

    2014-05-01

    Coral reef ecosystems maintain high primary productivity though the seawater is extremely oligotrophic. One of the hypotheses to explain this paradox is the recycling of nutrients in animal-algal symbiotic organisms such as corals. It is relatively easy to measure nutrient uptake rates by corals from seawater, but the proportion of internally circulating nutrients between the coral host and the endosymbiotic algae (zooxanthellae) is more challenging. Here, we performed a long-term and continuous 15N-labelling experiment to quantify the proportionate contribution of seawater (external N source) and the animal host (internal N source) to the total N influx in the endosymbiotic algae. Branches from the scleractinian corals Porites cylindrica and Montipora digitata from Okinawa, Japan, were cultured for 2 months in indoor, flow-through, filtered seawater tanks with the continuous supply of 15N-labelled nitrate. At the initial and after 2, 4, and 9 weeks of the study, coral branches were collected and the algal and animal fractions were separated for isotopic analyses. In both corals, the N isotope ratio of symbiotic algae exponentially increased and the values were much higher than those of the host tissue, suggesting that the algae had a faster turnover N time than the animal host. Algal and host N biomass normalized to the coral surface area slowly decreased in both coral species over the study period. To calculate the contribution of internal and external N, a simple mixing model of algal N metabolism was designed. Using differential equations of 15N balance and N biomass balance, F1 and F2 (external and internal N fluxes to symbiotic algae, respectively) were expressed as the functions of time. The model calculations showed that F2 was much higher than F1 in P. cylindrica and the percentage of internal N to the total influx N (PIN) was >70%. On the other hand, the contribution of F1 and F2 was comparable in M. digitata and the PIN was 40-70%. These results

  1. CARBON-RICH PRESOLAR GRAINS FROM MASSIVE STARS: SUBSOLAR {sup 12}C/{sup 13}C AND {sup 14}N/{sup 15}N RATIOS AND THE MYSTERY OF {sup 15}N

    Energy Technology Data Exchange (ETDEWEB)

    Pignatari, M. [Konkoly Observatory, Research Centre for Astronomy and Earth Sciences, Hungarian Academy of Sciences, Konkoly Thege Miklos ut 15-17, H-1121 Budapest (Hungary); Zinner, E. [Laboratory for Space Sciences and Physics Department, Washington University, St. Louis, MO 63130 (United States); Hoppe, P. [Max Planck Institute for Chemistry, D-55128 Mainz (Germany); Jordan, C. J.; Gibson, B. K. [E.A. Milne Centre for Astrophysics, Dept of Physics and Mathematics, University of Hull, HU6 7RX (United Kingdom); Trappitsch, R. [Department of the Geophysical Sciences and Chicago Center for Cosmochemistry, Chicago, IL 60637 (United States); Herwig, F. [Department of Physics and Astronomy, University of Victoria, Victoria, BC V8P5C2 (Canada); Fryer, C. [Computational Physics and Methods (CCS-2), LANL, Los Alamos, NM, 87545 (United States); Hirschi, R. [Keele University, Keele, Staffordshire ST5 5BG (United Kingdom); Timmes, F. X. [The Joint Institute for Nuclear Astrophysics, Notre Dame, IN 46556 (United States)

    2015-08-01

    Carbon-rich grains with isotopic anomalies compared to the Sun are found in primitive meteorites. They were made by stars, and carry the original stellar nucleosynthesis signature. Silicon carbide grains of Type X and C and low-density (LD) graphites condensed in the ejecta of core-collapse supernovae. We present a new set of models for the explosive He shell and compare them with the grains showing {sup 12}C/{sup 13}C and {sup 14}N/{sup 15}N ratios lower than solar. In the stellar progenitor H was ingested into the He shell and not fully destroyed before the explosion. Different explosion energies and H concentrations are considered. If the supernova shock hits the He-shell region with some H still present, the models can reproduce the C and N isotopic signatures in C-rich grains. Hot-CNO cycle isotopic signatures are obtained, including a large production of {sup 13}C and {sup 15}N. The short-lived radionuclides {sup 22}Na and {sup 26}Al are increased by orders of magnitude. The production of radiogenic {sup 22}Ne from the decay of {sup 22}Na in the He shell might solve the puzzle of the Ne-E(L) component in LD graphite grains. This scenario is attractive for the SiC grains of type AB with {sup 14}N/{sup 15}N ratios lower than solar, and provides an alternative solution for SiC grains originally classified as nova grains. Finally, this process may contribute to the production of {sup 14}N and {sup 15}N in the Galaxy, helping to produce the {sup 14}N/{sup 15}N ratio in the solar system.

  2. Provenancing Archaeological Wool Textiles from Medieval Northern Europe by Light Stable Isotope Analysis (δ13C, δ15N, δ2H)

    Science.gov (United States)

    von Holstein, Isabella C. C.; Walton Rogers, Penelope; Craig, Oliver E.; Penkman, Kirsty E. H.; Newton, Jason; Collins, Matthew J.

    2016-01-01

    We investigate the origin of archaeological wool textiles preserved by anoxic waterlogging from seven medieval archaeological deposits in north-western Europe (c. 700–1600 AD), using geospatial patterning in carbon (δ13C), nitrogen (δ15N) and non-exchangeable hydrogen (δ2H) composition of modern and ancient sheep proteins. δ13C, δ15N and δ2H values from archaeological wool keratin (n = 83) and bone collagen (n = 59) from four sites were interpreted with reference to the composition of modern sheep wool from the same regions. The isotopic composition of wool and bone collagen samples clustered strongly by settlement; inter-regional relationships were largely parallel in modern and ancient samples, though landscape change was also significant. Degradation in archaeological wool samples, examined by elemental and amino acid composition, was greater in samples from Iceland (Reykholt) than in samples from north-east England (York, Newcastle) or northern Germany (Hessens). A nominal assignment approach was used to classify textiles into local/non-local at each site, based on maximal estimates of isotopic variability in modern sheep wool. Light element stable isotope analysis provided new insights into the origins of wool textiles, and demonstrates that isotopic provenancing of keratin preserved in anoxic waterlogged contexts is feasible. We also demonstrate the utility of δ2H analysis to understand the location of origin of archaeological protein samples. PMID:27764106

  3. δ13C and d15N in the endangered Kemp’s ridley sea turtle Lepidochelys kempii after the Deepwater Horizon oil spill

    Science.gov (United States)

    Reich, Kimberly J.; López-Castro, Melania C.; Shaver, Donna J.; Iseton, Claire; Hart, Kristen M.; Hooper, Michael J.; Schmitt, Christopher J.

    2017-01-01

    The Deepwater Horizon explosion in April 2010 and subsequent oil spill released 3.19 × 106 barrels (5.07 × 108 L) of MC252 crude oil into important foraging areas of the endangered Kemp’s ridley sea turtle Lepidochelys kempii (Lk) in the northern Gulf of Mexico (GoM). We measured δ13C and δ15N in scute biopsy samples from 33 Lk nesting in Texas during 2010–-12. Of these, 27 were equipped with satellite transmitters and were tracked to traditional foraging areas in the northern GoM after the spill. Differences in δ13C between the oldest and newest scute layers from 2010 nesters were not significantly different, but δ13C in the newest layers from 2011 and 2012 nesters was significantly lower compared to 2010. δ15N differences were not statistically significant. Collectively, the stable isotope and tracking data indicate that the lower δ13C values reflect the incorporation of oil rather than changes in diet or foraging area. Discriminant analysis indicated that 51.5% of the turtles sampled had isotope signatures indicating oil exposure. Growth of the Lk population slowed in the years following the spill. The involvement of oil exposure in recent population trends is unknown, but long-term effects may not be evident for many years. Our results indicate that C isotope signatures in scutes may be useful biomarkers of sea turtle exposure to oil.

  4. Hyperpolarized (13) C,(15) N2 -Urea MRI for assessment of the urea gradient in the porcine kidney

    DEFF Research Database (Denmark)

    Hansen, Esben S S; Stewart, Neil J; Wild, Jim M;

    2016-01-01

    function in healthy porcine kidneys resembling the human physiology. METHODS: Five healthy female Danish domestic pigs (weight 30 kg) were scanned at 3 Tesla (T) using a (13) C 3D balanced steady-state MR pulse sequence following injection of hyperpolarized (13) C,(15) N2 -urea via a femoral vein catheter...

  5. Synthesis and biosynthesis of {sup 13}C-, {sup 15}N-labeled deoxynucleosides useful for biomolecular structural determinations

    Energy Technology Data Exchange (ETDEWEB)

    Ashburn, D.A.; Garcia, K.; Hanners, J.L.; Silks, L.A. III; Unkefer, C.J. [Los Alamos National Laboratory, NM (United States)

    1994-12-01

    Currently, there is a great emphasis on elucidating the structure, function, and dynamics of DNA. Much of the research involved in this study uses nuclear magnetic resonance (NMR) spectroscopy. Effective use of NMR spectroscopy for DNA molecules with mw > 10,000 requires stable isotope enrichment. We present strategies for site-specific isotopic labeling of the purine bases adenosine and guanosine and the biosynthesis of (U-{sup 13}C, {sup 15}N) DNA from methylotropic bacteria. With commercially available 6-chloropurine, an effective two-step route leads to 2{prime}-deoxy-(amino-{sup 15}N)adenosine (dA). The resulting d(amino-{sup 15}N)A is used in a series of reactions to synthesize 2{prime}-deoxy-(2-{sup 13}C,1,amino-{sup 15}N{sub 2})guanosine or any combination thereof. An improved biosynthesis of labeled DNA has been accomplished using Methylobacterium extorquens AS1. Each liter of growth medium contains 4 g of methanol to yield 1 g of lyophilized cells. As much as 200 mg of RNA per liter of culture has been obtained. We are currently developing large-scale isolation protocols. General synthetic pathways to oligomeric DNA will be presented.

  6. Contrasting food web linkages for the grazing pathway in 3 temperate forested streams using {sup 15}N as a tracer

    Energy Technology Data Exchange (ETDEWEB)

    Tank, J.L.; Mulholland, P.J.; Meyer, J.L.; Bowden, W.B.; Webster, J.R.; Peterson, B.J.

    1998-11-01

    Nitrogen is a critical element controlling the productivity and dynamics of stream ecosystems and many streams are limited by the supply of biologically available nitrogen. The authors are learning more about the fate of inorganic nitrogen entering streams through {sup 15}N tracer additions. The Lotic Intersite Nitrogen Experiment (LINX) is studying the uptake, cycling, and fate of {sup 15}N-NH{sub 4} in the stream food web of 10 streams draining different biomes. Using the {sup 15}N tracer method and data from 3 sites in the study, the authors can differentiate patterns in the cycling of nitrogen through the grazing pathway (N from the epilithon to grazing macroinvertebrates) for 3 temperate forested streams. Here, they quantify the relationship between the dominant grazer and its proposed food resource, the epilithon, by comparing {sup 15}N levels of grazers with those of the epilithon, as well as the biomass, nitrogen content, and chlorophyll a standing stocks of the epilithon in 3 streams.

  7. Analysis of 15N incorporation into D-alanine: a new method for tracing nitrogen uptake by bacteria

    NARCIS (Netherlands)

    Veuger, B.; Middelburg, J.J.; Boschker, H.T.S.; Houtekamer, M.J.

    2005-01-01

    The quantitative contribution of bacteria to total microbial uptake of nitrogenous substrates is an aspect of the aquatic nitrogen cycle that is still largely unclear, mainly because existing methods are generally inadequate. We investigated the feasibility of measuring 15N incorporation into bacter

  8. Insight on RDX degradation mechanism by Rhodococcus strains using 13C and 15N kinetic isotope effects.

    Science.gov (United States)

    Bernstein, Anat; Ronen, Zeev; Gelman, Faina

    2013-01-02

    The explosive Hexahydro-1,3,5-trinitro-1,3,5-triazine (RDX) is known to be degraded aerobically by various isolates of the Rhodococcus species, with denitration being the key step, mediated by Cytochrome P450. Our study aimed at gaining insight into the RDX degradation mechanism by Rhodococcus species and comparing isotope effects associated with RDX degradation by distinct Rhodococcus strains. For these purposes, enrichment in (13)C and (15)N isotopes throughout RDX denitration was studied for three distinct Rhodococcus strains, isolated from soil and groundwater in an RDX-contaminated site. The observable (15)N enrichment throughout the reaction, together with minor (13)C enrichment, suggests that N-N bond cleavage is likely to be the key rate-limiting step in the reaction. The similarity in the kinetic (15)N isotope effect between the three tested strains suggests that either isotope-masking effects are negligible, or are of a similar extent for all tested strains. The lack of variability in the kinetic (15)N isotope effect allows the interpretation of environmental studies with greater confidence.

  9. Heteronuclear transverse and longitudinal relaxation in AX4 spin systems: application to (15)N relaxations in (15)NH4(+).

    Science.gov (United States)

    Werbeck, Nicolas D; Hansen, D Flemming

    2014-09-01

    The equations that describe the time-evolution of transverse and longitudinal (15)N magnetisations in tetrahedral ammonium ions, (15)NH4(+), are derived from the Bloch-Wangsness-Redfield density operator relaxation theory. It is assumed that the relaxation of the spin-states is dominated by (1) the intra-molecular (15)N-(1)H and (1)H-(1)H dipole-dipole interactions and (2) interactions of the ammonium protons with remote spins, which also include the contribution to the relaxations that arise from the exchange of the ammonium protons with the bulk solvent. The dipole-dipole cross-correlated relaxation mechanisms between each of the (15)N-(1)H and (1)H-(1)H interactions are explicitly taken into account in the derivations. An application to (15)N-ammonium bound to a 41kDa domain of the protein DnaK is presented, where a comparison between experiments and simulations show that the ammonium ion rotates rapidly within its binding site with a local correlation time shorter than approximately 1ns. The theoretical framework provided here forms the basis for further investigations of dynamics of AX4 spin systems, with ammonium ions in solution and bound to proteins of particular interest.

  10. Determination of 15N abundance in nanogram pools of NO3 - and NO2 - by denitrification bioassay and mass spectrometry

    DEFF Research Database (Denmark)

    Højberg, Ole; Johansen, H. S.; Sorensen, J.

    1994-01-01

    Suspensions of two strains of Pseudomonas aeruginosa (ON12 and ON12-1) were used to reduce NO3 - and NO2 -, respectively, to N2O. The evolved N2O was quantified by gas chromatography with electron capture detection, and the 15N abundance was determined by mass spectrometry with a special inlet sy...

  11. Proton-decoupled CPMG: a better experiment for measuring (15)N R2 relaxation in disordered proteins.

    Science.gov (United States)

    Yuwen, Tairan; Skrynnikov, Nikolai R

    2014-04-01

    (15)N R2 relaxation is one of the most informative experiments for characterization of intrinsically disordered proteins (IDPs). Small changes in nitrogen R2 rates are often used to determine how IDPs respond to various biologically relevant perturbations such as point mutations, posttranslational modifications and weak ligand interactions. However collecting high-quality (15)N relaxation data can be difficult. Of necessity, the samples of IDPs are often prepared with low protein concentration and the measurement time can be limited because of rapid sample degradation. Furthermore, due to hardware limitations standard experiments such as (15)N spin-lock and CPMG can sample the relaxation decay only to ca. 150ms. This is much shorter than (15)N T2 times in disordered proteins at or near physiological temperature. As a result, the sampling of relaxation decay profiles in these experiments is suboptimal, which further lowers the precision of the measurements. Here we report a new implementation of the proton-decoupled (PD) CPMG experiment which allows one to sample (15)N R2 relaxation decay up to ca. 0.5-1s. The new experiment has been validated through comparison with the well-established spin-lock measurement. Using dilute samples of denatured ubiquitin, we have demonstrated that PD-CPMG produces up to 3-fold improvement in the precision of the data. It is expected that for intrinsically disordered proteins the gains may be even more substantial. We have also shown that this sequence has a number of favorable properties: (i) the spectra are recorded with narrow linewidth in nitrogen dimension; (ii) (15)N offset correction is small and easy to calculate; (iii) the experiment is immune to various spurious effects arising from solvent exchange; (iv) the results are stable with respect to pulse miscalibration and rf field inhomogeneity; (v) with minimal change, the pulse sequence can also be used to measure R2 relaxation of (15)N(ε) spins in arginine side chains. We

  12. Variability of plant nitrogen and water use in a 100-m transect of a subdesertic depression of the Ebro valley (Spain) characterized by leaf δ13C and δ15N

    Science.gov (United States)

    Peñuelas, Josep; Filella, Iolanda; Terradas, Jaume

    1999-04-01

    We studied carbon and nitrogen isotopic composition ( δ13C and δ15N) in sunlit leaves of four dominant species ( Rosmarinus officinalis L., Stipa parviflora L., Juniperus thurifera L. and Pinus halepensis L.) in a characteristic gradient of water and nitrogen availability produced by relief and micrometeorology in a subdesertic valley of central-NE Spain. Minimum values of δ13C were found at the foothills, and higher values were found both in the valley and on the top of the hill where water availability was lower. However, different species (functional groups) presented different δ13C values in the same valley. The lowest values of δ15N were found on the top of the hill and the highest ones in the valley, where N losses would thus be higher. In general, when growing together, trees showed 2 % higher values for δ13C as well as for δ15N than shrubs and grasses. The specific responses show that they use different available water and nitrogen resources within small catchments. For this ecosystem type, C and N isotope analyses are sensitive enough to resolve fine spatial and functional patterns even over a very short distance (100 m), where topography generates great gradients in microclimate, hydrology, soil physical conditions, vegetation and biogeochemistry.

  13. Bulk δ(15) N measurements of organic-rich rock samples by elemental analyzer/isotope ratio mass spectrometry with enhanced oxidation ability.

    Science.gov (United States)

    Han, Wennian; Feng, Lianjun; Li, Hongwei; Liu, Wei

    2017-01-15

    Elemental analyzer/isotope ratio mass spectrometry (EA/IRMS) has been widely used for nitrogen isotope ratio determination in various organic and inorganic samples. However, the extent of the redox reaction in the EA reaction tube can greatly affect the accuracy and precision of measurements, especially in the case of complex geological samples. It is therefore necessary to determine the appropriate reaction conditions to reach a high recovery of nitrogen by complete combustion or thermal decomposition and quantitative reduction. The conventional Dumas dual-inlet method was used to determine the bulk nitrogen isotope composition of SGR-1 (an organic-rich standard sample), which then was analyzed by EA/IRMS under different EA reaction conditions to study the influence of the redox environment on the δ(15) N measurements. The measured data together with the results reported by previous researchers were used to evaluate the effectiveness of the nitrogen extraction for organic-rich rock samples. Our results demonstrated that with the Dumas dual-inlet method more oxidizing agent (CuO) addition to SGR-1 would yield a higher nitrogen content of 0.91% than the recommended content (0.81%) although a δ(15) N value of 17.39 ± 0.09‰ was consistent with the recommended value by USGS. Using EA/IRMS, when more O2 was injected in the reaction tube, a high nitrogen content (0.92 ± 0.01%) and a δ(15) N value (17.43 ± 0.17‰) close to that of the Dumas dual-inlet method were obtained. The addition of V2 O5 or CuO in a continuous-flow system of EA/IRMS could not effectively enable the complete combustion of SGR-1. When measuring the nitrogen isotope composition of organic-rich rock sample dominated by reduced substances with EA/IRMS, greater O2 injection will enable more complete combustion to obtain reliable nitrogen yields compared with the addition of V2 O5 or CuO. Copyright © 2016 John Wiley & Sons, Ltd. Copyright © 2016 John Wiley & Sons, Ltd.

  14. Upper limits to the fractionation of isotopes due to atmospheric escape: Implications for potential 14N/15N in Pluto's atmosphere

    Science.gov (United States)

    Mandt, K.; Mousis, O.

    2014-12-01

    Formation and evolution of the solar system is studied in part using stable isotope ratios that are presumed to be primordial, or representative of conditions in the protosolar Nebula. Comets, meteorites and giant planet atmospheres provide measurements that can reasonably be presumed to represent primordial conditions while the terrestrial planets, Pluto and Saturn's moon Titan have atmospheres that have evolved over the history of the solar system. The stable isotope ratios measured in these atmospheres are, therefore, first a valuable tool for evaluating the history of atmospheric escape and once escape is constrained can provide indications of conditions of formation. D/H ratios in the atmosphere of Venus provide indications of the amount of water lost from Venus over the history of the solar system, while several isotope ratios in the atmosphere of Mars provide evidence for long-term erosion of the atmosphere. We have recently demonstrated that the nitrogen ratios, 14N/15N, in Titan's atmosphere cannot evolve significantly over the history of the solar system and that the primordial ratio for Titan must have been similar to the value recently measured for NH3 in comets. This implies that the building blocks for Titan formed in the protosolar nebula rather than in the warmer subnebula surrounding Saturn at the end of its formation. Our result strongly contrasts with works showing that 14N/15N in the atmosphere of Mars can easily fractionate from the terrestrial value to its current value due to escape processes within the lifetime of the solar system. The difference between how nitrogen fractionates in Mars and Titan's atmospheres presents a puzzle for the fractionation of isotopes in an atmosphere due to atmospheric escape. Here, we present a method aiming at determining an upper limit to the amount of fractionation allowed to occur due to escape, which is a function of the escape flux and the column density of the atmospheric constituent. Through this

  15. Timelike gamma* N -> Delta form factors and Delta Dalitz decay

    CERN Document Server

    Ramalho, G

    2012-01-01

    We extend a covariant model, tested before in the spacelike region for the physical and lattice QCD regimes, to a calculation of the gamma* N -> Delta reaction in the timelike region, where the square of the transfered momentum, q^2, is positive (q^2>0). We estimate the Dalitz decay Delta -> Ne+e- and the Delta distribution mass distribution function. The results presented here can be used to simulate the NN -> NNe+e- reactions at moderate beam kinetic energies.

  16. Transporte do 15N e produtividade do tomateiro enxertado irrigado com água carbonatada Transport of 15N and yield of the grafted tomato irrigated with carbonated water

    Directory of Open Access Journals (Sweden)

    Roberto Botelho Ferraz Branco

    2007-03-01

    Full Text Available Verificou-se a ação do dióxido de carbono dissolvido na água de irrigação e da enxertia do tomateiro no transporte de 15N nos tecidos da planta e na produção da cultura. Os tratamentos foram constituídos pela aplicação de CO2, 5 e 10 L min-1, mais a testemunha (dose zero e plantas enxertadas e pés-francos de tomateiro. O experimento foi conduzido no delineamento inteiramente casualizado, em esquema fatorial 3x2, com três repetições. As variáveis analisadas nas folhas e nos frutos da planta foram a produção de massa seca, o nitrogênio total, o excesso de 15N, a quantidade de nitrogênio proveniente do fertilizante e a porcentagem de recuperação do fertilizante e a produção de frutos comerciais. De acordo com os resultados estatísticos não houve diferença significativa entre os tratamentos do experimento em todas as variáveis analisadas. O CO2 dissolvido na água de irrigação e a enxertia do tomateiro não interferiram no transporte de 15N para os tecidos da parte aérea do tomateiro e tampouco em sua produção.We evaluated the action of the carbon dioxide dissolved in the irrigation water and the grafting of the tomato in the transport of 15N in the tissue of the plant and in the production of the culture. The treatments were the CO2 doses (0; 5 and 10 L min-1 and grafted and ungrafted tomato plant. These treatments were arranged in a 3x2 factorial scheme, in completely randomized design, with three replications. The variables analysed in the leaves and fruits were dry mass production, total nitrogen, excess of 15N, amount of nitrogen originated from the fertilizer, percentage of recovery of the fertilizer and commercial fruits production. There was no significant statistical difference among the treatments for any variable. The carbon dioxide dissolved in the irrigation water and the grafting of the tomato did not interfere in the transport of 15N to the shoots tissue neither in the yield.

  17. Ion microscopy analysis of the intracellular distribution of {sup 14}C-or {sup 15}N-labelled cytotoxic drugs; Analyse par microscopie ionique de la distribution intracellulaire de drogues cytotoxiques marquees par {sup 14}C ou {sup 15}N

    Energy Technology Data Exchange (ETDEWEB)

    Bisagni, E.; Carrez, D.; Croisy, A.; Favaudon, V.; Guerquin-Kern, J.L.; Nguyen, C.H.; Rivalle, C. [Institut Curie, 91 - Orsay (France); Dennebouy, R.; Slodzian, G. [Paris-11 Univ., 91 - Orsay (France); Galle, P. [Faculte de Medecine, 94 - Creteil (France)

    1994-12-31

    This study has concerned the localization, by the means of ion microscopy of human tumoral cells (in culture), of two synthesized cytostatic compounds: BD40 or Pazelliptine and Intoplicine. These two active compounds (cancer research) have been labelled either with {sup 15}N on the terminal amino dialkyl group of the lateral chain, either, for Intoplicine, with {sup 14}C on the carbon 3 of the aromatic cycle. These two drugs are considered as poisons for topo-isomerases, and they were used to localize these cellular multiplication key-enzymes. Unfortunately, pazelliptine and intoplicine specificity appeared much too low. However, encouraging results were obtained, particularly on {sup 15}N-labelling utilization. 4 figs., 9 refs.

  18. Delta II commercial space transportation

    Science.gov (United States)

    Meyers, J. F.

    1988-07-01

    Delta II is an upgraded variant of the Delta family of launch vehicles that has been in use by NASA since 1960. Among the design improvements incorporated by Delta II is a cryogenic-propellant second stage, a 2.89-m diameter satellite-protecting nose fairing, graphite/epoxy solid rocket motor cases, and 12:1 main engine expansion nozzle. The manufacturer/operator offers Delta II customers a dedicated, single satellite launch capability fully tailored to the given spacecraft's unique mission requirements.

  19. Leaf allocation patterns and 13C and 15N natural abundances of tropical lianas (Passiflora sp.) as dependent on external climbing support.

    Science.gov (United States)

    Werth, Martin; Spiegel, Ann-Kathrin; Kazda, Marian

    2013-01-01

    The transformation from self-supporting lianas to host-supported climbing lianas is related to re-allocation of biomass and nutrients among plant organs. Therefore, first, variations in leaf mass per area (LMA), leaf carbon and nitrogen allocation and (13)C and (15)N natural abundances were analysed among three tropical Passiflora species (P. edulis, P. ligularis, and P. tripartita) in a greenhouse study. Second, the influence of a climbing support was considered for each species and parameter. P. ligularis leaves were most enriched in (13)C in both treatments when compared with the other two species. This enrichment was caused by a high LMA, which is related to a high internal resistance to CO(2) diffusion. For P. edulis and P. tripartita, δ(13)C was additionally increasing with nitrogen content per area. Generally, there were no differences when considering carbon and nitrogen allocation to leaves of host-supported and self-supporting lianas. The only hints towards increased investment into leaves after the transition from self-supporting to host-supported stages could be seen by a trend to increased leaf areas and masses. δ(13)C values of supported P. edulis or P. tripartita plants were significantly increasing faster than those of non-supported plants once the interactions of leaf mass or nitrogen content per area were accounted for. Hence, the offer of a climbing support had only a minor impact on δ(13)C or δ(15)N values in vitro, but this could be different with increasing age of lianas in vivo.

  20. Simple approach for the preparation of 15-15N2-enriched water for nitrogen fixation assessments: Evaluation, application and recommendations

    Directory of Open Access Journals (Sweden)

    Isabell eKlawonn

    2015-08-01

    Full Text Available Recent findings revealed that the commonly used 15N2 tracer assay for the determination of dinitrogen (N2 fixation can underestimate the activity of aquatic N2-fixing organisms. Therefore, a modification to the method using pre-prepared 15-15N2-enriched water was proposed. Here, we present a rigorous assessment and outline a simple procedure for the preparation of 15-15N2-enriched water. We recommend to fill sterile-filtered water into serum bottles and to add 15-15N2 gas to the water in amounts exceeding the standard N2 solubility, followed by vigorous agitation (vortex mixing ≥5 min. Optionally, water can be degassed at low-pressure (≥950 mbar for ten minutes prior to the 15-15N2 gas addition to indirectly facilitate the 15-15N2 dissolution. This preparation of 15-15N2-enriched water can be done within one hour using standard laboratory equipment. The final 15N-atom% excess was 5% after replacing 2–5% of the incubation volume with 15-15N2-enriched water. Notably, the addition of 15-15N2-enriched water can alter levels of trace elements in the incubation water due to the contact of 15-15N2-enriched water with glass, plastic and rubber ware during its preparation. In our tests, levels of trace elements (Fe, P, Mn, Mo, Cu, Zn increased by up to 0.1 nmol L-1 in the final incubation volume, which may bias rate measurements in regions where N2 fixation is limited by trace elements. For these regions, we tested an alternative way to enrich water with 15-15N2. The 15-15N2 was injected as a bubble directly to the incubation water, followed by gentle shaking. Immediately thereafter, the bubble was replaced with water to stop the 15-15N2 equilibration. This method achieved a 15N-atom excess of 6.6±1.7% when adding 2 mL 15-15N2 per liter of incubation water. The herein presented methodological tests offer guidelines for the 15N2 tracer assay and thus, are crucial to circumvent methodological draw-backs for future N2 fixation assessments.

  1. Phenotypic expressions of CCR5-Delta 32/Delta 32 homozygosity

    NARCIS (Netherlands)

    Nguyen, GT; Carrington, M; Beeler, JA; Dean, M; Aledort, LM; Blatt, PM; Cohen, AR; DiMichele, D; Eyster, ME; Kessler, CM; Konkle, B; Leissinger, C; Luban, N; O'Brien, SJ; Goedert, JJ; O'Brien, TR

    1999-01-01

    Objective: As blockade of CC-chemokine receptor 5 (CCR5) has been proposed as therapy for HIV-1, we examined whether the CCR5-Delta 32/Delta 32 homozygous genotype has phenotypic expressions other than those related to HIV-1. Design: Study subjects were white homosexual men or men with hemophilia

  2. Phenotypic expressions of CCR5-Delta 32/Delta 32 homozygosity

    NARCIS (Netherlands)

    Nguyen, GT; Carrington, M; Beeler, JA; Dean, M; Aledort, LM; Blatt, PM; Cohen, AR; DiMichele, D; Eyster, ME; Kessler, CM; Konkle, B; Leissinger, C; Luban, N; O'Brien, SJ; Goedert, JJ; O'Brien, TR

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