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Sample records for 15n natural abundance

  1. Change of 15N natural abundance15N) in a forest soil receiving elevated N deposition

    Natural abundance of 15N15N) has been used to interpret N mineralization in forest ecosystems. Forest litter typically has depleted δ15N values ranging from -8 to 0 per mille and δ15N values of organic N in forest soil profiles become more enriched with depth. This study investigated (1) the change of δ15N and total N with depth, and (2) the relation between the change of δ15N within the 0 to 10, 10 to 20 and 20 to 30 cm intervals of the mineral layer and the N mineralization rates in these layers

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

    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.

  3. Bradyrhizobium strain and the 15N natural abundance quantification of biological N2 fixation in soybean

    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 15N natural abundance technique to quantify BNF inputs, it is essential to determine, with accuracy, the 15N 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 δ15N natural abundance in a non-labelled soil, and estimate of the contribution of BNF derived from the use of 15N-isotope dilution in soils enriched with 15N. To evaluate N2 fixation by soybean, three non-N2-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 N2 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 N2 fixation. (author)

  4. Variation of natural 15N abundance15N) in greenhouse tomato and available nitrogen in soil supplied with cow manure or chemical fertilizers

    Cow manure or chemical fertilizers applied to greenhouse-grown tomato changed N contents and natural 15N abundance15N) in tomato plants and the δ15N values of available N in soil. Cow manure increased and chemical fertilizers decreased the δ15N values of tomato plants. In the early periods of tomato culture with cow manure, the δ15N values of nitrate nitrogen of soil were higher than those of whole cow manure N, and, thereafter, dropped to δ15N values between those of soil and cow manure. Application of chemical fertilizers to soil immediately raised the δ15N values of ammonium nitrogen in soil but they dropped quickly to δ15N values between those of soil and fertilizers. On the estimation of the soil-derived N, manure-derived N and fertilizer-derived N in tomato plants based on the δ15N values of sources, much caution should be paid concerning the isotopic variation caused by N sources and isotopic fractionation during N transformation in soil. (author)

  5. Use of 15N Natural Abundance and N Species Concentrations to Assess N-Cycling in Constructed and Natural Coastal

    Natural abundance of N stable isotopes used in combination with concentrations may be useful indicators of N-cycling in wetlands. Concentrations and 15N signatures of NO3-, NH4 and sediment organic nitrogen (SON) were measured in two impacted coastal golf course retention ponds and two natural marshes. Limited NO3 was detected in natural site surface water or pore water, but both isotopic signature and concentrations of NO3- in surface water of impacted sites indicated anthropogenic inputs. In natural sites, NH4 concentrations were greatest in deeper pore water and least in surface water, suggesting diffusion predominates. The natural sites had greater % SON, and 15N indicated that the natural sites also had greater NH4+ released from SON mineralization than impacted sites. In NO3--limited systems, neither concentrations nor 15N natural abundance was able to provide information on N-cycling, while processes associated with NH4+ were better elucidated by using both concentrations and 15N natural abundance

  6. Estimation of symbiotic dinitrogen fixation in alder forest by the method based on natural 15N abundance

    Annual N2-fixation in virgin forest ecosystems has been measured using a 15N natural abundance15N)procedure. This method was compared to a 15N labelled fertilizer isotopic dilution method. For young alders (5-6 years old), δ15N of leaves gave results in good agreement with the isotopic dilution of fertilizer method. Since δ15N variability was expected according to plant physiology, for alder trees, leaves were collected at various heights after the end of the growing season, and, to take account of isotopic variations coming from derived inputs, δ15N of leaves of a large number of other plants in the same area were measured to give control values. Following this procedure, the δ15N method gave reliable evaluation of the nitrogen supply, by through N2-fixation, to alders, which were found to maintain high nitrogen fixing capacity in a sequence ranging from first stage of establishment of climactic formation. Moreover, the same method is reported to discriminate various origins of Alnus glutinosa grown in natural conditions, possibly in relation to the genetic diversity of this species. (author). 22 refs., 3 figs., 2 tabs

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

    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)

  8. Feasibility analysis of organic Tea authentication using 15N natural abundance method

    Organic agricultural products were always adulterated by pollutant-free agricultural products in market because of lacking of available authentication technique. Organic tea was one of the largest organic agricultural products in China which are facing the same problem and can not be accepted by consumers. In this paper, based on the newest information of δ 15N from soil-plant-fertilizer system, a new method was suggested to identify whether N fertilizer was applied to organic tea in producing processing. Meanwhile, the principle of this new method and its feasibility were discussed. (authors)

  9. Short-range spatial variability of soil δ15N natural abundance – effects on symbiotic N2-fixation estimates in pea

    Holdensen, Lars; Hauggaard-Nielsen, Henrik; Jensen, Erik Steen

    2007-01-01

    The δ15N natural abundance (‰) of the total soil N pool varies at the landscape level, but knowledge on short-range variability and consequences for the reliability of isotopic methods are poorly understood. The short-range spatial variability of soil δ15N natural abundance as revealed by the 15N...... abundance in spring barley and N2-fixing pea was measured within the 0.15-4 m scale at flowering and at maturity. The short-range spatial variability of soil δ15N natural abundance and symbiotic nitrogen fixation were high at both growth stages. Along a 4-m row, the δ15N natural abundance in barley...... reference plants varied up to 3.9 ‰, and sometimes this variability was observed even between plants grown only 30 cm apart. The δ15N natural abundance in pea varied up to 1.4  ‰ within the 4-m row. The estimated percentage of nitrogen derived from the atmosphere (%Ndfa) varied from 73-89% at flowering...

  10. Variations in natural abundances of 15N and 13C in potassium fed lentil plants grown under water stress

    The impact of two K-fertilizer treatments [K0 (0) and K1 (150 kg K2O/ha)] on dry matter production and N2 fixation (Ndfa) by Lentil (Lens culinaris.) was evaluated in a pot experiment. The plants were also subjected to three soil moisture regimes starting from bud flower initiation stage to pod formation (low, 45-50%. Moderate, 55-60% and high 75-80% of field capacity, abbreviated as FC1, FC2 and FC3, respectively). The 15N natural abundance technique (%δ 15N) was employed to evaluate N2 fixation using barley as a reference crop. Moreover, the carbon isotope discrimination (%Δ 13C) was determined to assess factors responsible for crop performance variability in the different treatments. Water restriction occurring during the post-flowering period considerably affects growth and N2-fixation. However, K-fertilizer enhanced plant performance by overcoming water shortage influences. The delta 15N values in lentils ranged from +0.67 to +1.36% depending on soil moisture and K-fertilizer treatments. Whereas, those of N2 fixation and the reference plant were -0.45 and +2.94%, respectively. Consequently, Ndfa% ranged from 45 and 65%. Water stress reduced Δ 13C values in the FC1K0 And FC1K1 treatments. However, K fertilizer enhanced the whole plants Δ 13C along with dry matter yield and N2 fixation. The water stressed plants amended with K (FC1K1) seemed to be the best treatment because of its highest pod yield, high N balance and N2-fixation with low consumption of irrigation water. This illustrates the ecological and economical importance of K-fertilizer in alleviating water stress occurring during the post-flowering period of lentil.(Authors)

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

    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.

  12. Variations in natural abundances of 15N and 13C in potassium fed lentil plants grown under water stress

    The impact of two K-fertilizer treatments [K0 (0) and K1 (150 kg K2O/ha)] on dry matter production and N2 fixation (Ndfa) by Lentil (Lens culinaris.) was evaluated in a pot experiment. The plants were also subjected to three soil moisture regimes starting from bud flower initiation stage to pod formation (low, 45-50%; moderate, 55-60% and high 75-80% of field capacity, abbreviated as FC1, FC2 and FC3, respectively). The 15N natural abundance technique (%δ 15N) was employed to evaluate N2 fixation using barley as a reference crop. Moreover, the carbon isotope discrimination (%Δ 13C) was determined to assess factors responsible for crop performance variability in the different treatments. Water restriction occurring during the post-flowering period considerably affects growth and N2-fixation. However, K-fertilizer enhanced plant performance by overcoming water shortage influences. The δ 15N values in lentils ranged from +0.67 to +1.36% depending on soil moisture and K-fertilizer treatments; whereas, those of N2 fixation and the reference plant were -0.45 and +2.94%, respectively. Consequently, Ndfa% ranged from 45 and 65%. Water stress reduced Δ 13C values in the FC1K0 And FC1K1 treatments. However, K fertilizer enhanced the whole plants Δ 13C along with dry matter yield and N2fixation. The water stressed plants amended with K (FC1K1) seemed to be the best treatment because of its highest pod yield, high N balance and N2-fixation with low consumption of irrigation water. This illustrates the ecological and economical importance of K-fertilizer in alleviating water stress occurring during the post-flowering period of lentil.(Authors)

  13. 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

    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...

  14. 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

    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

  15. Utilization of natural variations in the isotopic abundance of 15N to trace the source of aquifer pollution by nitrates

    The validity of using the natural isotope nitrogen-15 to trace the source of nitrates contained in aquifers is discussed with reference to experimental devices (lysimeters and experimental plots) and for examples chosen from the Paris area. There are a number of sources of nitrates: (1) industrially synthesized nitrates (fertilizers); (2) nitrates produced by oxidation of organic matter associated with human, agricultural or urban activities; (3) nitrates synthesized in the soil by the decay of organic matter. In the examples studied these sources differ in their 15N content: (1) fertilizers have a delta15N close to zero (atmospheric nitrogen); (2) the nitrates originating from organic pollution have high delta15N (above 10-12 per mille) and this 15N enrichment is associated with the volatilization of ammonia during the ammonia stage of mineralization; (3) the isotopic characterization of the nitrates produced by organic matter in the soil is less evident. Citing several examples, the author demonstrates that these three sources are diffentiated isotopically. Consideration of the parameters nitrate concentration/isotopic composition reveals simple mixture curves. In the most complicated cases - where there is association with other isotopic (3H) or chemical parameters - it is possible qualitatively to trace the sources of nitrogen pollution

  16. Variation of natural sup 15 N abundance of crops and soils in Japan with special reference to the effect of soil conditions and fertilizer application

    Yoneyama, Tadakatsu (National Agriculture Research Center, Tsukuba, Ibaraki (Japan). Dept. of Soils and Fertilizers); Kouno, Kazumi; Yazaki, Jinya

    1990-12-01

    The natural {sup 15}N abundance ({delta}{sup 15}N) of the crops subjected to long-term fertilizer treatments under paddy and upland conditions in the different experimental stations throughout Japan were analyzed. The {delta}{sup 15}N values of the grains of paddy rice which were +6.3 per mille on the average in the fields without application of chemical fertilizers decreased by the treatment with chemical fertilizers. The average {delta}{sup 15}N values of the upland crops were lower than those of paddy rice without application of N fertilizers. The {delta}{sup 15}N values of upland crops decreased with the dose of chemical fertilizer N, but increased with the application of composts containing animal feces. The pot experiments using three soils showed that the {delta}{sup 15}N values of paddy rice were higher than those of upland rice and sorghum and that these values were comparable to the {delta}{sup 15}N values of ammonium and nitrate produced in the incubated soils, respectively. The {delta}{sup 15}N values of fertilizer N absorbed by paddy rice were higher than those of fertilizer N, whereas the {delta}{sup 15}N values of the fertilizer N in upland rice and sorghum were increased in the alluvial soils but decreased in Andosols as compared to those of fertilizer N applied. The {delta}{sup 15}N values of the Andosols in Japan showed small variations, with an average value of +6.5 per mille, whereas those of alluvial soils in Japan showed large variations with an average value lower than that of Andosols. (author).

  17. Variation of natural 15N abundance of crops and soils in Japan with special reference to the effect of soil conditions and fertilizer application

    The natural 15N abundance15N) of the crops subjected to long-term fertilizer treatments under paddy and upland conditions in the different experimental stations throughout Japan were analyzed. The δ15N values of the grains of paddy rice which were +6.3 per mille on the average in the fields without application of chemical fertilizers decreased by the treatment with chemical fertilizers. The average δ15N values of the upland crops were lower than those of paddy rice without application of N fertilizers. The δ15N values of upland crops decreased with the dose of chemical fertilizer N, but increased with the application of composts containing animal feces. The pot experiments using three soils showed that the δ15N values of paddy rice were higher than those of upland rice and sorghum and that these values were comparable to the δ15N values of ammonium and nitrate produced in the incubated soils, respectively. The δ15N values of fertilizer N absorbed by paddy rice were higher than those of fertilizer N, whereas the δ15N values of the fertilizer N in upland rice and sorghum were increased in the alluvial soils but decreased in Andosols as compared to those of fertilizer N applied. The δ15N values of the Andosols in Japan showed small variations, with an average value of +6.5 per mille, whereas those of alluvial soils in Japan showed large variations with an average value lower than that of Andosols. (author)

  18. Natural isotopes abundance of 15N and 13C in leaves of some N2-fixing and non N2-fixing trees and shrubs in Syria

    Variability in the natural abundance isotopes of 15N and 13C in leaves of several legume and non-legume plant species grown at different sites of two areas in semi-arid regions of Syria was determined. In the first area (non-saline soil), the 15N values of a number of fixing and non-fixing reference plants ranged from -2.09 to +9.46, depending on plant species and studied site. 15N in a number of legume species including Acacia cyanopylla (-1.73), Acacia farnesiana (-0.55), Prosopis juliflora (-1.64) and Medicago arborea (+1.6) were close to the atmospheric value pointing to a major contribution of N2 fixing in these species; whereas, those of reference plants were highly positive (between +3.6 and +9.46%). In the actinorhizal tree, Elaeagnus angustifolia, the 15N abundance was far lower (-0.46 to -2.1%) strongly suggesting that the plant obtained large proportional contribution from BNF. In contrast, δ15N values in some other legumes and actinorhizal plants were relatively similar to those of reference plants, suggesting that the contribution of fixed N2 is negligible. On the other hand, δ13C% values in leaves of C3 plants were affected by plant species, ranging from a minimum of -28.67% to a maximum of -23%. However, they were the same within each plant species although they were grown at different sites. Moreover, dual stable isotope analysis in leaves of Prosopis juliflora and other non- legumes grown on a salt affected soil (second area) was also conducted. Results showed that salinity did not affect C assimilation in this woody legume since a higher carbon discrimination was obtained indicating that this plant is a salt tolerant species; whereas, N2-fixation was drastically affected (δ15N= +7.03). (Author)

  19. [Responses of Soil and Plant 15N Natural Abundance to Long-term N Addition in an N-Saturated Pinus massoniana Forest in Southwest China].

    Liu, Wen-jing; Kang, Rong-hua; Zhang, Ting; Zhu, Jing; Duan, Lei

    2015-08-01

    Increasing N deposition in China will possibly cause N saturation of forest ecosystem, further resulting in a series of serious environmental problems. In order to explore the response of forest ecosystem to N deposition in China, and further evaluate and predict the N status of ecosystem, the 15N natural abundance (delta 15N) of soil and plants was measured in a typical Masson pine (Pinus massoniana) forest in southwest China to examine the potential use of delta 15N enrichment factor (epsilon(p/s)) as an effective indicator of N status. Long-term high N addition could significantly increase delta 15N of soil and plants, which was suggested by an on-going N fertilizing experiment with NH4NO3 or NaNO3 for 7 years. Meanwhile, delta 15N of soil and plants under NH, deposition was significantly higher than that under NO- deposition, suggesting different responses of ecosystem to different N-forms of deposition. The "N enrichment factor (epsilon(p/s)) had positive correlations with N deposition, N nitrification, and N leaching in the soil water. Linear correlation between "N enrichment factor and N deposition was found for all Masson pine forests investigated in this and previous studies in China, demonstrating that 15N enrichment factor could be used as an indicator of N status. The NH3 emission control should also be carried out accompanying with NOx emission control in the future, because NH4- deposition had significantly greater impact on the forest ecosystem than NO3- deposition with the same equivalence. PMID:26592030

  20. Natural abundance of /sup 15/N in soil organic matter with special reference to paddy soils in Japan. Biogeochemical implications on the nitrogen cycle

    Wada, Eitaro; Imaizumi, Reiko (Mitsubishi Chemical Industries Ltd., Tokyo (Japan)); Takai, Yasuo

    1984-01-01

    In order to explain the general principle which controls the /sup 15/N content of soil organic nitrogen, experimental rice fields which were fertilized for long term were investigated. The /sup 15/N abundance values of rice plants vary according to the kinds of fertilizer, e.g., chemical fertilizer and green manure. The significant difference of /sup 15/N abundance was recognized between rice plants and fertilizers. Nitrification and denitrification seemed to be responsible for the difference. But these have minor effect on the variation of /sup 15/N abundance of soil because rice plants assimilate all available nitrogen and are removed from paddy fields by harvest. Consequently, the effects of nitrification-denitrification and ammonia volatilization are observed only in biological process such as the growth of rice plants and hydrophytes. A long term addition of fertilizers clearly increased the amount of soil organic nitrogen in paddy fields. Based on isotope mass balance, nitrogen isotope fractionation factor of 0.9942 was estimated in the process of epidiagenesis which indicates the selective decomposition of heavy isotopic species. An addition of ammonium sulfate with low /sup 15/N abundance decreased the /sup 15/N content of soil nitrogen in the paddy fields with the depletion of soil organic nitrogen. OrgC/clay ratio was demonstrated as an important factor which controls the /sup 15/N abundance value in paddy soil. The relation between the /sup 15/N abundance value in soil organic nitrogen and OrgC/clay ratio was able to be presented by hyperbola for the paddy soild so far examined. The /sup 15/N abundance of source and plant nitrogen two isotopic fractionation associated with the epidiagenesis of soil organic matter and the adsorption of ammonia by clay minerals are the three major factors determining the /sup 15/N abundance of soil organic nitrogen.

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

    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-1 yr-1. In addition to the effect of deposition on the nitrogen content of the two species, its influence on 15N natural abundance15N 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; δ15N-values reflected the ratio of NH4-N to NO3-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

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

    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. PMID:20183233

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

    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 12N and 13C 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 δ15N values in four legume species (Acacia cyanopylla, -1.73 %; Acacia farnesiana, -0.55%; Prosopis juliflora, -1.64%, and Medicago arborea, +1.6%) and one actinorhizal plant (Elaeagnus angustifolia, -0.46 to -2.1%) were found to be close to that of the atmospheric value pointing to a major contribution of N2 fixing in these species; whereas, δ15N values of the non-fixing plant species were highly positive.δ13C% in leaves of the C3 plants were found to be affected by plant species, ranging from a minimum of -28.67% to a maximum of -23%. 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 (Δ3C%) was exhibited by Prosopis juliflora indicating that the latter is a salt tolerant species; however, its δ 15N was highly positive (+7.03%) suggesting a negligible contribution of the fixed N2. Hence, it was concluded that the enhancement of N2 fixation might be achieved by selection of salt-tolerant rhizobium strains. (author)

  4. Using the natural abundance of 13C and 15N to examine soil organic matter accumulated during 100 years of cropping

    The 13C natural abundance technique was applied to soils of a long term experimental field in the study of organic matter turnover. The technique allowed evaluation of soil organic matter (SOM) originating from residues of different cropping systems that partially replaced the native prairie SOM mineralized during 100 years of cropping history. A large pool of the prairie SOM was highly resistant to decay, demonstrating a turnover time of 1000 years. Labile prairie SOM, lost when cultivation was initiated, had a half-life of 11 years. Accumulated SOM that originated from residues of a particular crop demonstrated a similar half-life as it decayed and was replaced by new SOM from residues of a different crop. Apparent turnover time for soil organic carbon calculated from annual input of crop residues to the soil for different cropping systems ranged from 2 years for corn to 6.4 years for timothy sod. The natural abundance of 15N showed significant change for soil treated with chemical fertilizer or manure relative to the control soil. Manure applied to timothy for 100 years contributed 24% of existing soil organic nitrogen. (author). 12 refs, 2 figs, 3 tabs

  5. Importance of drought stress and nitrogen fixation in the desert legume Alhagi sparsifolia - Results from 13C and 15N natural-abundance studies in the field

    Ecological adaptation of plant species to arid environments is poorly understood. Water and nitrogen are likely to be the two major constraints to growth and production in the Taklamakan desert (35 mm annual precipitation). Plants must have special adaptations to avoid lethal water deficits. Moreover, the supply of inorganic nitrogen sources, e.g. nitrate and ammonium, may be restricted due to diminished mineralization. Therefore, as a legume, nitrogen fixation may play an important role in the nutrition of A. sparsifolia. To be able to make recommendations for sustainable use of Alhagi, a study on natural abundance of the stable isotopes, 13C and 15N, was conducted in the foreland of Qira oasis at the southern rim of the Taklamakan desert. Alhagi bushes were sampled monthly during 1999, and carbon-isotope composition of leaves and leaf solutes were investigated as measures of long-term and short-term water restriction, respectively. Preliminary investigations in 1998 of Alhagi plants led to the assumption that individuals growing near the fields of the oasis assimilated inorganic nitrogen forms such as NO3- or NH4+ (δ15N values of 5 to 8), whereas individuals growing close to the desert used N2 fixation as their main source of nitrogen (δ15N values near zero). Therefore, Alhagi plants were sampled along a gradient from the oasis into the desert. The carbon-isotope data revealed that all Alhagi species were well supplied with water throughout the season. The δ13C values of leaves and solutes were consistently negative, indicating no long- or shortterm drought stress at any time, and this was supported by other water-relations data. Thus, Alhagi plants seem to have contact with groundwater and an efficient water-conducting system; moisture deficiency was not a limiting factor. The δ15N values of Alhagi leaves along a 5-km gradient from the Qira Research Station into the desert showed no significant trend. Some plants were clearly fixing atmospheric N2, but most

  6. Determinação da fixação biológica de nitrogênio no amendoim forrageiro (Arachis spp. por intermédio da abundância natural de 15N Determination of biological nitrogen fixation by the forage groundnut (Arachis spp. using the 15N natural abundance technique

    Cesar Heraclides Behling Miranda

    2003-12-01

    Full Text Available Quantificou-se a fixação biológica de nitrogênio (FBN em cinco acessos de Arachis pintoi (BRA31534, BRA31828, BRA31796, BRA15121 e BRA30333 e dois de A. repens (BRA31801 e BRA31861. Os mesmos foram estabelecidos em um solo Latosolo Vermelho Escuro sujeito a inundação estacional, sendo a FBN estimada segundo a técnica da abundância natural do isótopo 15N (d15N. Estolões dos acessos foram plantados em novembro de 1999, em parcelas de 2,0 m x 2,0 m, com quatro repetições, distribuídas em blocos ao acaso. A massa verde das plantas acima de cinco centímetros do solo foi colhida em janeiro de 2000 e seca em estufa a 65ºC até peso constante, sendo posteriormente pesada e moída para análise dos conteúdos em N e d15N, em espectrômetro de massa. Verificaram-se diferenças significativas entre os genótipos quanto à produção de matéria seca (MS e N total, sobressaindo-se BRA31534 e BRA31828, com produções de 4,2 t/ha e conteúdos totais de N de 102 e 110 kg/ha, respectivamente. Os acessos BRA30333 e BRA31861 produziram apenas 2,6 t de MS/ha, com 59 e 65 kg/ha de N total, respectivamente. As taxas de FBN dos acessos testados, medidas por comparação dos seus teores de d15N com os de plantas não fixadoras crescendo na mesma área, variaram de 36% (BRA15121 a 90% (BRA31828 do N total das plantas, equivalente a 26 e 99 kg de N/ha, respectivamente. Verificou-se correlação positiva e significativa (r = 0,92, pThe biological nitrogen fixation (BNF of five Arachis pintoi (BRA31534, BRA31828, BRA31796, BRA15121 E BRA30333 and two A. repens (BRA31801 e BRA31861 accessions, grown in a Dark Red Latosol prone to seasonal flooding was evaluated using the 15N natural abundance method (d15N. Stolons of each accession were planted in November 1999, in plots of 2.0 m by 2.0 m, with four replications allotted to randomized blocks. Plant mass above five cm was harvested in January 2000. There were significant differences among the tested

  7. Growth and N2-fixation of Dhaincha C-3/Sorghum C-4 and Dhaincha C-3/Sunflower C-3 intercropping systems using the 15N and 13C natural abundance method technique

    A field experiment on dhaincha C3 (Sesbania aculeata Pers), sunflower C3 (Helianthus annuus L.) and sorghum C4 (Sorghum bicolor L.) plants grown in monocropping and intercropping systems was conducted to evaluate seed yield, dry matter production, total N yield, land equivalent ratio (LER), intraspecific competition for soil N uptake, water use efficiency (WUE) and N2-fixation using the 15N natural abundance technique (δ 15N). Moreover, carbon isotope discrimination (Δ 13C) was determined to assess factors responsible for crop performance variability in the different cropping systems. (author)

  8. Comparing the Influence of Wildfire and Prescribed Burns on Watershed Nitrogen Biogeochemistry Using 15N Natural Abundance in Terrestrial and Aquatic Ecosystem Components

    Stephan, Kirsten; Kathleen L. Kavanagh; Koyama, Akihiro

    2015-01-01

    We evaluated differences in the effects of three low-severity spring prescribed burns and four wildfires on nitrogen (N) biogeochemistry in Rocky Mountain headwater watersheds. We compared paired (burned/unburned) watersheds of four wildfires and three spring prescribed burns for three growing seasons post-fire. To better understand fire effects on the entire watershed ecosystem, we measured N concentrations and δ15N in both the terrestrial and aquatic ecosystems components, i.e., soil, under...

  9. Nitrogen balance and 15N abundance in a long-term organic matter experiment

    In along-term field experiment on a clay loam soil at Uppsala, Sweden, changes of nitrogen contents and the natural abundance of 15N in the topsoils receiving various organic amendments at the rate of 2000 kg C ha-1 y-1 and different rates of nitrogen were studied. Cropping resulted in clearly lower N-losses from the topsoil (0-20 cm) compared to the bare fallow plots. Green manure, animal manure and sewage sludge increased the Nt-inventory significantly and 15N abundances were clearly affected by N-input differing in isotopic signature through the amendments. A N-balance and half-lives of the introduced nitrogen were calculated. Refs. 7 (author)

  10. Growth and N2-fixation of Dhaincha C-3/Sorghum C-4 and Dhaincha C-3/Sunflower C-3 intercropping systems using the 15N and 13C natural abundance method technique

    A field experiment on dhaincha C3 (Sesbania aculeata Pers), sunflower C3 (Helianthus annuus L.) and sorghum C4 (Sorghum bicolor L.) plants grown in monocropping and intercropping systems was conducted to evaluate seed yield, dry matter production, total N yield, land equivalent ratio (LER), intraspecific competition for soil N uptake, water use efficiency (WUE) and N2-fixation using the 15N natural abundance technique (δ 15N). Moreover, carbon isotope discrimination (Δ13C) was determined to assess factors responsible for crop performance variability in the different cropping systems. Intercropping of sesbania/sorghum showed greater efficiency over monocropping in producing dry matter, during the entire growth period, as indicated by the LERs (>1); whereas, the efficiency of producing dry matter in the sesbania /sunflower intercropping was similar to that in the monocropping system (LER=1). Moreover, sorghum plants (C4) was more competitive than sesbania (C3) for soil N uptake; whereas, sesbania seemed to be more competitive than its associated sunflower (C3). N uptake in the mixed stand of sesbania/sorghum was improved due to the increase in soil N uptake by the component sorghum and the higher root nodule activity of component sesbania without affecting the amount of N2 fixed. In both cropping systems, sesbania plants fixed almost the same amount of N2 (an average of 105 kg N/ha) although the number of rows in the mixed stand was 2/3 of that in the pure stand. This gives an advantage of the intercropping over sole cropping system with regards to N2-fixation. 13C discrimination in plant materials was found to be affected by plant species and the cropping system. Factors affected Δ13C in plants grown in the mixed stand relative to solely grown crops are discussed.(author)

  11. Carbono, nitrogênio e abundância natural de δ13c e δ15n em uma cronossequência de agricultura sob plantio direto no cerrado goiano

    Roni Fernandes Guareschi

    2014-08-01

    Full Text Available A conversão do cerrado nativo em sistemas agropecuários pode alterar com o passar dos anos de cultivo os teores de C e N, bem como o sinal isotópico do δ13C e δ15N do solo. Desta forma, o objetivo deste trabalho foi avaliar os teores de C, N e abundância natural de δ13C e δ15N no perfil do solo em uma cronossequência de agricultura sob sistema plantio direto (SPD no cerrado goiano. Para isso, em Montividiu, GO, foram selecionadas áreas sob SPD com diferentes tempos de implantação: SPD com três anos de implantação (SPD3, SPD com 15 anos de implantação (SPD15 e SPD com 20 anos de implantação (SPD20, as quais foram comparadas com áreas de cerrado nativo (CE e pastagem (PA. Foram coletadas amostras de solo nas profundidades de 0,00-0,05; 0,05-0,10; 0,10-0,20; 0,20-0,30; 0,30-0,40; 0,40-0,50; 0,50-0,60; 0,60-0,80; e 0,80-1,00 m. O solo das áreas de estudo foi classificado como Latossolo Vermelho distroférrico. O manejo do solo sob SPD após 20 anos aumentou os teores de C e N na camada superficial do solo (0,00-0,05 m, em relação às outras áreas avaliadas. Nas demais profundidades avaliadas, observou-se que está ocorrendo aumento nos teores C e N com o passar dos anos de adoção do SPD (três para 15 anos; no entanto, tais áreas ainda não foram capazes de recuperar os teores desses elementos em relação à vegetação nativa de CE. Por meio dos resultados de δ13C, pôde-se constatar que a origem da MOS nas áreas de SPD é referente à plantas do ciclo fotossintético C4. Verificou-se que até os 0,30 m do perfil do solo os resultados de δ13C estão reduzindo com o passar dos anos de adoção do SPD. Os menores e maiores valores de δ15N foram encontrados nas áreas de CE e PA, SPD3, enquanto SPD15 e SPD20 apresentaram valores intermediários de δ15N, em relação às demais áreas avaliadas.

  12. Denitrification by intact soybean nodules in relation to natural 15N enrichment of nodules

    The natural 15N abundance of nodules of soybeans (Glycine max (L.) Merrill) which are actively fixing N2 is considerably higher than other tissues. To investigate the question of whether isotopic fractionation associated with denitrification by bacteroids causes this 15N enrichment, we inoculated soybeans with two strains of Rhizobium japonicum. Free-living cultures of one of these (strain USDA 33) were unable to denitrify or respire NO3-, while free-living cultures of the second (strain USDA 138) were capable of denitrification. USDA 138 formed nodules which fixed N2 very efficiently. The N of these nodules was enriched in 15N and the nodules reduced a substantial amount of NO3- to NO2- and N2O. Nodules infected with USDA 33 fixed about half as much N2 as those infected with USDA 138. The former nodules were enriched in 15N (although less so than nodules infected with USDA 138), despite the fact that the nodules formed by USDA 33 did not reduce NO3-. Clearly denitrification could not have been the cause of 15N enrichment of nodules infected with strain USDA 33. Alternative causes of 15N enrichment of soybean nodules and their possible metabolic significance are discussed

  13. 15N abundance in Antarctica: origin of soil nitrogen and ecological implications

    The results of an investigation of the nitrogen cycle in Antartica are reported which show that nitrate in Antarctic soils is extremely depleted in 15N compared with biogenic nitrogen and that algae collected from a nitrate-rich saline pond and from a penguin rookery exhibit, respectively, the lowest and the highest 15N/14N ratios among terrestrial biogenic nitrogen so far observed. The possible causes of these extreme nitrogen isotopic compositions are discussed. (U.K.)

  14. 15N and 13C abundances in marine environments with emphasis on biogeochemical structure of food networks

    Distributions of δ15N and δ13C for biogenic substances in the Antarctic Ocean and in the Otsuchi River estuary in Japan were investigated to construct isotope biogeochemical framework for assessing marine ecosystems. The isotopic compositions of phytoplankton were particularly low in the Antarctic Ocean. High nitrate and CO2 concentrations in the surface sea waters, and the low light intensity seem to enhance the kinetic isotope fractionations that preferred the depletion of 15N and 13C in the algal body. A clear-cut linear relationship between animal δ15N and its trophic level was obtained in the Antarctic system. In the estuary, the variation of isotope ratios were principally governed by the mixing of land-derived organic matter, marine phytoplankton, and seagrasses. A food-chain effect of 15N enrichment was also confirmed. An isotopically ordered structure was presented for a marine estuarine ecosystem. The isotopic abundances in a food network vary mainly because of the variation in 15N and 13C contents of primary producers grown under different environmental conditions and because of the enrichment of 15N along food chains. (author)

  15. Natural Nitrogen—15 Abundance of Ammonium Nitrogen and Fixed Ammonium in Soils

    SHISHU-LIAN; XINGGUANG-XI; 等

    1992-01-01

    The present article deals with the natural nitrogen-15 abundance of ammonium nitrogen and fixed ammonium in different soils.Variations in the natural 15N abundance of ammonium nitrogen mineralized in soils under anaerobic incubation condition were related to soil pH.The δ 15N of mineralizable N in acid soils was lower but that in neutral and calcareous soils was higher compared with the δ 15N of total N in the soils.A variation tendence was also found in the δ 15N of amino-acid N in the hydrolysates of soils.The natural 15N abundance of fixed ammonium was higher than that of total N in most surface soils and other soil horizons,indicating that the increase of δ 15N in the soil borizons beneath subsurface horizon of some forest soils and acid paddy soils was related to the higher δ 15N value of fixed ammonium in the soil.

  16. Revision of the 15N(p, γ)16O reaction rate and oxygen abundance in H-burning zones

    Caciolli, A.; Mazzocchi, C.; Capogrosso, V.; Bemmerer, D.; Broggini, C.; Corvisiero, P.; Costantini, H.; Elekes, Z.; Formicola, A.; Fülöp, Zs.; Gervino, G.; Guglielmetti, A.; Gustavino, C.; Gyürky, Gy.; Imbriani, G.; Junker, M.; Lemut, A.; Marta, M.; Menegazzo, R.; Palmerini, S.; Prati, P.; Roca, V.; Rolfs, C.; Rossi Alvarez, C.; Somorjai, E.; Straniero, O.; Strieder, F.; Terrasi, F.; Trautvetter, H. P.; Vomiero, A.

    2011-09-01

    Context. The NO cycle takes place in the deepest layer of a H-burning core or shell, when the temperature exceeds T ≃ 30 × 106 K. The O depletion observed in some globular cluster giant stars, always associated with a Na enhancement, may be due to either a deep mixing during the red giant branch (RGB) phase of the star or to the pollution of the primordial gas by an early population of massive asymptotic giant branch (AGB) stars, whose chemical composition was modified by the hot bottom burning. In both cases, the NO cycle is responsible for the O depletion. Aims: The activation of this cycle depends on the rate of the 15N(p, γ)16O reaction. A precise evaluation of this reaction rate at temperatures as low as experienced in H-burning zones in stellar interiors is mandatory to understand the observed O abundances. Methods: We present a new measurement of the 15N(p, γ)16O reaction performed at LUNA covering for the first time the center of mass energy range 70-370 keV, which corresponds to stellar temperatures between 65 × 106 K and 780 × 106 K. This range includes the 15N(p, γ)16O Gamow-peak energy of explosive H-burning taking place in the external layer of a nova and the one of the hot bottom burning (HBB) nucleosynthesis occurring in massive AGB stars. Results: With the present data, we are also able to confirm the result of the previous R-matrix extrapolation. In particular, in the temperature range of astrophysical interest, the new rate is about a factor of 2 smaller than reported in the widely adopted compilation of reaction rates (NACRE or CF88) and the uncertainty is now reduced down to the 10% level.

  17. Revision of the 15N(p,{\\gamma})16O reaction rate and oxygen abundance in H-burning zones

    Caciolli, A; Capogrosso, V; Bemmerer, D; Broggini, C; Corvisiero, P; Costantini, H; Elekes, Z; Formicola, A; Fulop, Zs; Gervino, G; Guglielmetti, A; Gustavino, C; Gyurky, Gy; Imbriani, G; Junker, M; Lemut, A; Marta, M; Menegazzo, R; Palmerini, S; Prati, P; Roca, V; Rolfs, C; Alvarez, C Rossi; Somorjai, E; Straniero, O; Strieder, F; Terrasi, F; Trautvetter, H P; Vomiero, A

    2011-01-01

    The NO cycle takes place in the deepest layer of a H-burning core or shell, when the temperature exceeds T {\\simeq} 30 {\\cdot} 106 K. The O depletion observed in some globular cluster giant stars, always associated with a Na enhancement, may be due to either a deep mixing during the RGB (red giant branch) phase of the star or to the pollution of the primordial gas by an early population of massive AGB (asymptotic giant branch) stars, whose chemical composition was modified by the hot bottom burning. In both cases, the NO cycle is responsible for the O depletion. The activation of this cycle depends on the rate of the 15N(p,{\\gamma})16O reaction. A precise evaluation of this reaction rate at temperatures as low as experienced in H-burning zones in stellar interiors is mandatory to understand the observed O abundances. We present a new measurement of the 15N(p,{\\gamma})16O reaction performed at LUNA covering for the first time the center of mass energy range 70-370 keV, which corresponds to stellar temperatures...

  18. 15N isotope biogeochemistry and natural denitrification process in groundwater: Application to the chalk aquifer of norther France

    The use of 15N natural isotope tracing in an aquifer contained within chalk rocks in northern France indicates that, under certain hydrogeological conditions, major denitrification occurs. At the boundary where the aquifer becomes confined, the nitrate concentrations decrease in the direction of groundwater flow accompanied by an exponential increase in 15N (expressed in δ15N) of the residual nitrate. This is characteristic of kinetic isotope effects, which accompany the reduction of the nitrate ion during denitrification. Hydrogeochemical and bacteriological observations confirm this process. Natural isotope tracing also permits this process to be distinguished from local dilution with nitrate-free water, which would entail a major drop in nitrate values without 15N isotopic enrichment. A model is proposed to explain the relatively small observed magnitude of the isotopic fractionation effect

  19. Will Abundant Natural Gas Solve Climate Change?

    McJeon, H. C.; Edmonds, J.; Bauer, N.; Leon, C.; Fisher, B.; Flannery, B.; Hilaire, J.; Krey, V.; Marangoni, G.; Mi, R.; Riahi, K.; Rogner, H.; Tavoni, M.

    2015-12-01

    The rapid deployment of hydraulic fracturing and horizontal drilling technologies enabled the production of previously uneconomic shale gas resources in North America. Global deployment of these advanced gas production technologies could bring large influx of economically competitive unconventional gas resources to the energy system. It has been hoped that abundant natural gas substituting for coal could reduce carbon dioxide (CO2) emissions, which in turn could reduce climate forcing. Other researchers countered that the non-CO2 greenhouse gas (GHG) emissions associated with shale gas production make its lifecycle emissions higher than those of coal. In this study, we employ five state-of-the-art integrated assessment models (IAMs) of energy-economy-climate systems to assess the full impact of abundant gas on climate change. The models show large additional natural gas consumption up to +170% by 2050. The impact on CO2 emissions, however, is found to be much smaller (from -2% to +11%), and a majority of the models reported a small increase in climate forcing (from -0.3% to +7%) associated with the increased use of abundant gas. Our results show that while globally abundant gas may substantially change the future energy market equilibrium, it will not significantly mitigate climate change on its own in the absence of climate policies.

  20. Natural Resource Abundance and Human Capital Accumulation

    Jean-Philippe C. Stijns

    2001-01-01

    This study examines indicators of human capital accumulation together with data for natural resource abundance and rents in a panel of 102 countries running from 1970 to 1999. Mineral wealth makes a positive and marked difference on human capital accumulation. Matching on observables reveals that cross-country results are not driven by a third factor such as overall economic development. Political stability does seem to affect both human capital accumulation and subsoil wealth, but not enough...

  1. Natural and artificial methods of 15N labelling of soil to estimate biological nitrogen fixation: Review of symposium papers

    Despite the many criticisms that have sometimes tended to limit confidence in the 15N methodologies, papers have been presented at the symposium to show the practical importance of the 15N methods, how to reduce postulated errors, and when errors due to reference crops can be ignored. Besides, in many situations, the required answers can be obtained without the need for a reference crop. (author). 21 refs

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

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

    2011-01-01

    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......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...... and straw fractions of the ancient cereal types; differences in δ15N between unmanured and PK treatments were insignificant. The offset in straw and grain δ15N due to manure averaged 7.9 and 8.8 ‰, respectively, while the soil offset was 1.9 ‰. The soil and biomass δ13C values were not affected by...

  3. Methods of 15N tracer research in biological systems

    The application of the stable isotope 15N is of increasing importance in different scientific disciplines, especially in medicine, agriculture, and the biosciences. The close correlation between the growing interest and improvements of analytical procedures resulted in remarkable advances in the 15N tracer technique. On the basis of the latest results of 15N tracer research in life sciences and agriculture methods of 15N tracer research in biological systems are compiled. The 15N methodology is considered under three headings: Chemical analysis with a description of methods of sample preparation (including different separation and isolation methods for N-containing substances of biological and agricultural origin) and special procedures converting ammonia to molecular nitrogen. Isotopic analysis with a review on the most important methods of isotopic analysis of nitrogen: mass spectrometry (including the GC-MS technique), emission spectrometry, NMR spectroscopy, and other analytical procedures. 15N-tracer techniques with a consideration of the role of the isotope dilution analysis as well as different labelling techniques and the mathematical interpretation of tracer data (modelling, N turnover experiments). In these chapters also sources of errors in chemical and isotopic analysis, the accuracy of the different methods and its importance on tracer experiments are discussed. Procedures for micro scale 15N analysis and aspects of 15N analysis on the level of natural abundance are considered. Furthermore some remarks on isotope effects in 15N tracer experiments are made. (author)

  4. The analysis of 15N/14N ratios in natural samples, with emphasis on nitrate and ammonium in precipitation

    The nitrogen cycle is one of the most important of the earth's elemental cycles. The report describes the procedures used for the analysis of 15N/14N ratios in ammonium and nitrate (and organic nitrogen), and summaries without discussion the data obtained for precipitation (by rain and dust) collected at the Council for Scientific and Industrial Research site. The 15N/14N ratios of nitrogen compounds were determined on N2 gas. This was measured by means of a mass spectrometer. The isotopic analysis of organic nitrogen were conducted in two ways: Kjeldahl digestion to form ammonium, and Dumas combustion directly to N2

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

    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.

  6. Nicotine, acetanilide and urea multi-level2H-,13C- and15N-abundance reference materials for continuous-flow isotope ratio mass spectrometry

    Schimmelmann, A.; Albertino, A.; Sauer, P.E.; Qi, H.; Molinie, R.; Mesnard, F.

    2009-01-01

    Accurate determinations of stable isotope ratios require a calibration using at least two reference materials with different isotopic compositions to anchor the isotopic scale and compensate for differences in machine slope. Ideally, the S values of these reference materials should bracket the isotopic range of samples with unknown S values. While the practice of analyzing two isotopically distinct reference materials is common for water (VSMOW-SLAP) and carbonates (NBS 19 and L-SVEC), the lack of widely available organic reference materials with distinct isotopic composition has hindered the practice when analyzing organic materials by elemental analysis/isotope ratio mass spectrometry (EA-IRMS). At present only L-glutamic acids USGS40 and USGS41 satisfy these requirements for ??13C and ??13N, with the limitation that L-glutamic acid is not suitable for analysis by gas chromatography (GC). We describe the development and quality testing of (i) four nicotine laboratory reference materials for on-line (i.e. continuous flow) hydrogen reductive gas chromatography-isotope ratio mass-spectrometry (GC-IRMS), (ii) five nicotines for oxidative C, N gas chromatography-combustion-isotope ratio mass-spectrometry (GC-C-IRMS, or GC-IRMS), and (iii) also three acetanilide and three urea reference materials for on-line oxidative EA-IRMS for C and N. Isotopic off-line calibration against international stable isotope measurement standards at Indiana University adhered to the 'principle of identical treatment'. The new reference materials cover the following isotopic ranges: ??2Hnicotine -162 to -45%o, ??13Cnicotine -30.05 to +7.72%, ?? 15Nnicotine -6.03 to +33.62%; ??15N acetanilide +1-18 to +40.57%; ??13Curea -34.13 to +11.71%, ??15Nurea +0.26 to +40.61% (recommended ?? values refer to calibration with NBS 19, L-SVEC, IAEA-N-1, and IAEA-N-2). Nicotines fill a gap as the first organic nitrogen stable isotope reference materials for GC-IRMS that are available with different ??13N

  7. Studies on the feasibility of direct measurement of N losses as N2 and N2O produced by denitrification with 15N tracer technique and mass spectrometer

    With 15N tracer technique, mass spectrometer and a self-designed installation including sample entrance, reduced Cu tube, high-efficiency O2 trap, liquid N2 cold trap, a method for direct determination of N losses as N2 and N2O produced by denitrification is set up. The average of 15N natural abundance of atmospheric samples determined is 0.3659% (the theoretical value is 0.3660%) with C.V.% of 0.09% and an average of absolute error of 0.0002%, which is up to the error standard of the mass spectrometer used. C.V.% of measurement of 15N abundance in different gas samples and in the substrate NO3- undergoing denitrification are 0.03%-1.08% and 1.22%-5.21%, respectively, indicating that the pretreating installation is highly efficient for elimination of O2, CO2 and H2O in gas samples, and the method is feasible for direct measurement of 15N losses as N2 and N2O. As the calculation of 15N losses is based on atom excess % of 15N(15N abundance of gas sample minus 15N natural abundance of atmospheric N2), C.V.% of determination of 15N losses is probably larger than 5% if atom excess % of 15N in gas samples is smaller than 0.014%. It is suggested that the 15N abundance higher than 0.380% in gas samples be suitable

  8. Nature of organic carbon and nitrogen in physically protected organic matter of some Australian soils as revealed by solid-state 13 C and 15 N NMR spectroscopy

    The 13C and 15N nuclear magnetic resonance (NMR) spectroscopy was applied for characterising the chemical nature of the remaining organic fraction. The 13C NMR spectroscopic comparison of the residues after UV photo-oxidation and the untreated bulk soils revealed a considerable increase in condensed aromatic structures in the residues for 4 of the 5 soils. This behaviour was recently shown to be typical for char-containing soils. In the sample where no char was detectable by NMR spectroscopy, the physically protected carbon consisted of functional groups similar to those observed for the organic matter of the bulk sample, although their relative proportions were altered. The solid-state 15N NMR spectrum from this sample revealed that some peptide structures were able to resist UV photo-oxidation, probably physically protected within the core of micro aggregates. Heterocyclic aromatic nitrogen was not detected in this spectrum, but pyrrolic nitrogen was found to comprise a major fraction of the residues after photo-oxidation of the <53 μm containing soils. Acid hydrolysis of these samples confirmed that some peptide-like material was still present. The identification of a considerable amount of aromatic carbon and nitrogen, assignable to charred material in 4 of the 5 investigated soils, supports previous observations that char largely comprises the inert or passive organic matter pool of many Australian soils. The influence of such material on the carbon and nitrogen dynamics in such soils, however, requires further research. Copyright (2000) CSIRO Australia

  9. Application of the 15N gas-flux method for measuring in situ N2 and N2O fluxes due to denitrification in natural and semi-natural terrestrial ecosystems and comparison with the acetylene inhibition technique

    Sgouridis, Fotis; Stott, Andrew; Ullah, Sami

    2016-03-01

    Soil denitrification is considered the most un-constrained process in the global N cycle due to uncertain in situ N2 flux measurements, particularly in natural and semi-natural terrestrial ecosystems. 15N tracer approaches can provide in situ measurements of both N2 and N2O simultaneously, but their use has been limited to fertilized agro-ecosystems due to the need for large 15N additions in order to detect 15N2 production against the high atmospheric N2. For 15N-N2 analyses, we have used an "in-house" laboratory designed and manufactured N2 preparation instrument which can be interfaced to any commercial continuous flow isotope ratio mass spectrometer (CF-IRMS). The N2 prep unit has gas purification steps and a copper-based reduction furnace, and allows the analysis of small gas injection volumes (4 µL) for 15N-N2 analysis. For the analysis of N2O, an automated Tracegas Preconcentrator (Isoprime Ltd) coupled to an IRMS was used to measure the 15N-N2O (4 mL gas injection volume). Consequently, the coefficient of variation for the determination of isotope ratios for N2 in air and in standard N2O (0.5 ppm) was better than 0.5 %. The 15N gas-flux method was adapted for application in natural and semi-natural land use types (peatlands, forests, and grasslands) by lowering the 15N tracer application rate to 0.04-0.5 kg 15N ha-1. The minimum detectable flux rates were 4 µg N m-2 h-1 and 0.2 ng N m-2 h-1 for the N2 and N2O fluxes respectively. Total denitrification rates measured by the acetylene inhibition technique in the same land use types correlated (r = 0.58) with the denitrification rates measured under the 15N gas-flux method, but were underestimated by a factor of 4, and this was partially attributed to the incomplete inhibition of N2O reduction to N2, under a relatively high soil moisture content, and/or the catalytic NO decomposition in the presence of acetylene. Even though relatively robust for in situ denitrification measurements, methodological

  10. Application of the 15N-Gas Flux method for measuring in situ N2 and N2O fluxes due to denitrification in natural and semi-natural terrestrial ecosystems and comparison with the acetylene inhibition technique

    Sgouridis, F.; Ullah, S.; Stott, A.

    2015-08-01

    Soil denitrification is considered the most un-constrained process in the global N cycle due to uncertain in situ N2 flux measurements, particularly in natural and semi-natural terrestrial ecosystems. 15N tracer approaches can provide in situ measurements of both N2 and N2O simultaneously, but their use has been limited to fertilised agro-ecosystems due to the need for large 15N additions in order to detect 15N2 production against the high atmospheric N2. For 15N-N2 analyses, we have used an "in house" laboratory designed and manufactured N2 preparation instrument which can be interfaced to any commercial continuous flow isotope ratio mass spectrometer (CF-IRMS). The N2 prep unit has gas purification steps, a copper based reduction furnace, and allows the analysis of small gas injection volumes (4 μL) for 15N-N2 analysis. For the analysis of N2O, an automated Tracegas Pre-concentrator (Isoprime Ltd) coupled to an IRMS was used to measure the 15N-N2O (4 mL gas injection volume). Consequently, the coefficient of variation for the determination of isotope ratios for N2 in air and in standard N2O (0.5 ppm) was better than 0.5 %. The 15N Gas-Flux method was adapted for application in natural and semi-natural land use types (peatlands, forests and grasslands) by lowering the 15N tracer application rate to 0.04-0.5 kg 15N ha-1. For our chamber design (volume / surface = 8:1) and a 20 h incubation period, the minimum detectable flux rates were 4 μg N m-2 h-1 and 0.2 ng N m-2 h-1 for the N2 and N2O fluxes respectively. The N2 flux ranged between 2.4 and 416.6 μg N m-2 h-1, and the grassland soils showed on average 3 and 14 times higher denitrification rates than the woodland and organic soils respectively. The N2O flux was on average 20 to 200 times lower than the N2 flux, while the denitrification product ratio (N2O/N2 + N2O) was low, ranging between 0.03 and 13 %. Total denitrification rates measured by the acetylene inhibition technique under the same field conditions

  11. Application of the 15N-Gas Flux method for measuring in situ N2 and N2O fluxes due to denitrification in natural and semi-natural terrestrial ecosystems and comparison with the acetylene inhibition technique

    F. Sgouridis

    2015-08-01

    Full Text Available Soil denitrification is considered the most un-constrained process in the global N cycle due to uncertain in situ N2 flux measurements, particularly in natural and semi-natural terrestrial ecosystems. 15N tracer approaches can provide in situ measurements of both N2 and N2O simultaneously, but their use has been limited to fertilised agro-ecosystems due to the need for large 15N additions in order to detect 15N2 production against the high atmospheric N2. For 15N-N2 analyses, we have used an "in house" laboratory designed and manufactured N2 preparation instrument which can be interfaced to any commercial continuous flow isotope ratio mass spectrometer (CF-IRMS. The N2 prep unit has gas purification steps, a copper based reduction furnace, and allows the analysis of small gas injection volumes (4 μL for 15N-N2 analysis. For the analysis of N2O, an automated Tracegas Pre-concentrator (Isoprime Ltd coupled to an IRMS was used to measure the 15N-N2O (4 mL gas injection volume. Consequently, the coefficient of variation for the determination of isotope ratios for N2 in air and in standard N2O (0.5 ppm was better than 0.5 %. The 15N Gas-Flux method was adapted for application in natural and semi-natural land use types (peatlands, forests and grasslands by lowering the 15N tracer application rate to 0.04–0.5 kg 15N ha−1. For our chamber design (volume / surface = 8:1 and a 20 h incubation period, the minimum detectable flux rates were 4 μg N m−2 h−1 and 0.2 ng N m−2 h−1 for the N2 and N2O fluxes respectively. The N2 flux ranged between 2.4 and 416.6 μg N m−2 h−1, and the grassland soils showed on average 3 and 14 times higher denitrification rates than the woodland and organic soils respectively. The N2O flux was on average 20 to 200 times lower than the N2 flux, while the denitrification product ratio (N2O/N2 + N2O was low, ranging between 0.03 and 13 %. Total denitrification rates measured by the acetylene inhibition technique

  12. Relative Magnitude and Controls of in Situ N2 and N2O Fluxes due to Denitrification in Natural and Seminatural Terrestrial Ecosystems Using (15)N Tracers.

    Sgouridis, Fotis; Ullah, Sami

    2015-12-15

    Denitrification is the most uncertain component of the nitrogen (N) cycle, hampering our ability to assess its contribution to reactive N (Nr) removal. This uncertainty emanates from the difficulty in measuring in situ soil N2 production and from the high spatiotemporal variability of the process itself. In situ denitrification was measured monthly between April 2013 and October 2014 in natural (organic and forest) and seminatural ecosystems (semi-improved and improved grasslands) in two UK catchments. Using the (15)N-gas flux method with low additions of (15)NO3(-) tracer, a minimum detectable flux rate of 4 μg N m(-2) h(-1) and 0.2 ng N m(-2) h(-1) for N2 and N2O, respectively, was achieved. Denitrification rates were lower in organic and forest (8 and 10 kg N ha(-1) y(-1), respectively) than in semi-improved and improved grassland soils (13 and 25 kg N ha(-1) y(-1), respectively). The ratio of N2O/N2 + N2O was low and ranged from soil respiration, nitrate, C:N ratio, bulk density, moisture, and pH across the sites. Overall, the contribution of denitrification to Nr removal in natural ecosystems was ~50% of the annual atmospheric Nr deposition, making these ecosystems vulnerable to chronic N saturation. PMID:26509488

  13. Grass species influence on plant N uptake - Determination of atmospheric N deposition to a semi-natural peat bog site using a 15N labelling approach

    Hurkuck, Miriam; Brümmer, Christian; Spott, Oliver; Flessa, Heinz; Kutsch, Werner L.

    2014-05-01

    Large areas of natural peat bogs in Northwestern Germany have been converted to arable land and were subjected to draining and peat cutting in the past. The few protected peatland areas remaining are affected by high nitrogen (N) deposition. Our study site - a moderately drained raised bog - is surrounded by highly fertilized agricultural land and livestock production. In this study, we used a 15N pool dilution technique called 'Integrated Total Nitrogen Input' (ITNI) to quantify annual deposition of atmospheric N into biomonitoring pots over a two-year period. Since it considers direct N uptake by plants, it was expected to result in higher N input than conventional methods for determination of N deposition (e.g. micrometeorological approaches, bulk N samplers). Using Lolium multiflorum and Eriophorum vaginatum as monitor plants and low, medium and high levels of fertilization, we aimed to simulate increasing N deposition to planted pots and to allocate airborne N after its uptake by the soil-plant system in aboveground biomass, roots and soil. Increasing N fertilization was positively correlated with biomass production of Eriophorum vaginatum, whereas atmospheric plant N uptake decreased and highest airborne N input of 899.8 ± 67.4 µg N d-1 pot-1 was found for low N fertilization. In contrast, Lolium multiflorum showed a clear dependency of N supply on plant N uptake and was highest (688.7 ± 41.4 µg N d-1 pot-1) for highly fertilized vegetation pots. Our results suggest that grass species respond differently to increasing N input. While crop grasses such as Lolium multiflorum take up N according to N availability, species adopted to nutrient-limited conditions like Eriophorum vaginatum show N saturation effects with increasing N supply. Total airborne N input ranged from about 24 to 66 kg N ha-1 yr-1 dependent on the used indicator plant and the amount of added fertilizer. Parallel determination of atmospheric N deposition using a micrometeorological approach

  14. Sequential diffusion of ammonium and nitrate from soil extracts to a polytetrafluoroethylene trap for 15N determination

    A novel diffusion method was used for preparation of NH4+- and NO3--N samples from soil extracts for 15N determination. Ammonium, and nitrate following reduction to ammonia, are allowed to diffuse to an acid-wetted glass filter enclosed in polytetrafluoroethylene tape. The method was evaluated with simulated soil extracts obtained using 50 ml of 2 M potassium chloride solution containing 130 μg of NH4=-N (2.3 atom% 15N) and 120 μg of NO3--N (natural 15N abundance). No cross-over in the 15N abundances of NH4+-N and NO3--N was observed, indicating a quantitative diffusion process (72 h, 25 deg C). Owing to the presence of inorganic nitrogen impurities in the potassium chloride, the 15N enrichments should be corrected for the blank nitrogen content. (author). 8 refs.; 1 tab

  15. Spatial variation of N-2-fixation in field pea (Pisum sativum L.) at the field scale determined by the N-15 natural abundance method

    Hauggaard-Nielsen, Henrik; Holdensen, Lars; Wulfsohn, D.; Jensen, Erik Steen

    in pea 15N natural abundance of 1 δ unit between flowering and maturity and a reference crop decline of 1.3 δ15N unit over the same period increased noise of derived variables, making modeling of N2-fixation difficult. Furthermore, complex interactions with other soil variables and biotic stresses...... not measured in this study may have contributed significantly to the variability of fixation and yield of pea within the field. Pea N2-fixation obtained from two additional 10 ha farmer fields was in agreement with the other findings highlighting that N2-fixation takes place under a range of physical...

  16. Deuterium/hydrogen natural isotopic abundance in fruit juices

    Stable isotopic analyses of various elements such as carbon, hydrogen and oxygen are currently applied for the authentification of naturalness of fruit juices. Deuterium is particularly of interest because of the wide variation of its abundance. Due to evaporation-transpiration the deuterium content of the water in fruit juices is enriched compared to local ground water. In the case of our investigation on apple, another fractionation, originating in technological process, was observed. The concentrated juice water is enriched by 6o/oo as compared to natural fruit juice water. (authors)

  17. Chlorine-36 abundance in natural and synthetic perchlorate

    Heikoop, Jeffrey M [Los Alamos National Laboratory; Dale, M [NON LANL; Sturchio, Neil C [UNIV OF ILLIONOIS; Caffee, M [PURDUE UNIV; Belosa, A D [UNIV OF ILLINOIS; Heraty, Jr., L J [UNIV OF ILLINOIS; Bohike, J K [RESTON, VA; Hatzinger, P B [SHAW ENIVIORNMENTAL C0.; Jackson, W A [TEXAS TECH; Gu, B [ORNL

    2009-01-01

    Perchlorate (ClO{sub 4}{sup -}) is ubiquitous in the environment. It occurs naturally as a product of atmospheric photochemical reactions, and is synthesized for military, aerospace, and industrial applications. Nitrate-enriched soils of the Atacama Desert (Chile) contain high concentrations of natural ClO{sub 4}{sup -}; nitrate produced from these soils has been exported worldwide since the mid-1800's for use in agriculture. The widespread introduction of synthetic and agricultural ClO{sub 4}{sup -} into the environment has complicated attempts to understand the geochemical cycle of ClO{sub 4}{sup -}. Natural ClO{sub 4}{sup -} samples from the southwestern United States have relatively high {sup 36}Cl abundances ({sup 36}Cl/Cl = 3,100 x 10{sup -15} to 28,800 x 10{sup -15}), compared with samples of synthetic ({sup 36}Cl/Cl = 0.0 x 10{sup -15} to 40 x 10{sup -15}) and Atacama Desert ({sup 36}Cl/Cl = 0.9 x 10{sup -15} to 590 x 10{sup -15}) ClO{sub 4}{sup -}. These data give a lower limit for the initial {sup 36}Cl abundance of natural ClO{sub 4}{sup -} and provide temporal and other constraints on its geochemical cycle.

  18. Synthesis of [α-15N]-dl-tryptophan

    [α-15N]-dl-tryptophan was synthesized by the use of Al-Ni alloy catalytic hydrogenation from 15N-glycine via several steps. The overall yield of the final product was 46.9% and the abundance of 15N was about 93%. The physicochemical properties of the synthetic compound obtained were the same as those of the standard tryptophan. Its structure were confirmed by the elemental analyses, MS, UV and paper chromatography

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

    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 1.013, as...

  20. Struktur- und Bindungsuntersuchungen nichtextrahierbarer 15 N- und 14 C-Simazinrückstände im Boden

    Berns, Anne Elisabeth

    2003-01-01

    The aim of the presented study was the characterization of the structure and binding modes of non-extractable residues (NER) of the triazine herbicide simazine. The chemical environments of unaltered as well as metabolized simazine compounds can be observed directly in soil or compost matrix by 15N-NMR spectroscopy. As the 15N-isotope has a very low sensitivity and natural abundance 15N-labeled simazine was used. To further enhance the signal to noise ratio and sensitivity of the NMR experime...

  1. 15N tracer methodology for absorption studies in nutrition research

    Proceeding from 15N analyses, 15N tracer methods, and a model of protein metabolism it is shown that the nitrogen balance is a useful concept for expressing the relationship between the overall nitrogen intake of the body and the nitrogen excretion. After admistering low doses of 15N-labelled substances like protein and amino acids, the kinetics of digestion and absorption can be followed by measuring the 15N abundance in serum and urine of patients. A significant delay in the nitrogen absorption indicates gastrointestinal disorders

  2. Recent advances in the application of 13C and 15N NMR spectroscopy to soil organic matter studies

    Nuclear magnetic resonance (NMR) spectroscopy has been applied to many studies in soil science, geochemistry, and environmental science. In recent years, the study of soil organic matter (SOM) using NMR techniques has progressed rapidly. NMR spectroscopy has been used to study chemical changes of SOM during decomposition, and also of soil extract fractions such as humic acid and fulvic acid. NMR spectroscopy of soils has improved rapidly in recent years with the introduction of pre-treatment and particle-size fractionation. In addition to routine liquid- and solid-state 13C NMR applications, 15N NMR spectra of natural abundant samples have been reported, but 15N-enriched material is more convenient to use due to the low natural abundance of 15N. Some newly developed NMR techniques have also been utilised, such as 2-dimensional NMR spectroscopy and improved 1H NMR techniques. These are reviewed and commented on in this paper. Copyright (2000) CSIRO Publishing

  3. 15N NMR spectroscopy of Pseudomonas cytochrome c-551

    15N-1H correlation spectroscopy with detection at the 1H frequency has been used at natural abundance to detect nitrogen nuclei bonded to protons in the ferrocytochrome c-551 from Pseudomonas aeruginosa (ATCC 19429). Side-chain aromatic nitrogen, main-chain amides, and side-chain amides have been assigned to specific residues by comparison to previous proton assignments. Assignment ambiguities arising from overlap in the proton dimension have been resolved by examining spectra as a function of temperature and pH. Nitrogen chemical shifts are reported at pH 4.6 and 9.4 and three temperatures, 32, 50, and 60 degree C. Significant differences arise from the observed protein shifts and expected shifts in the random coil polypeptide

  4. CHANGE IN NATURAL ABUNDANCE OF 15N AND ESTIMATION OF N LOSSES FROM DAIRY MANURE DURING STORAGE BY MASS BALANCE AND NITROGEN-TO-PHOSPHORUS RATIO

    The main objective was to evaluate methodologies to estimate N losses from stored dairy manure. Manure with high N (HN) and low N (LN) content was obtained from two groups of cows assigned diets of 17 and 15% CP (DM), respectively. Manure collected from the barn floor was diluted with water to 10% ...

  5. Earthworm eco-physiological characteristics and quantification of earthworm feeding in vermifiltration system for sewage sludge stabilization using stable isotopic natural abundance

    Li, Xiaowei; Xing, Meiyan, E-mail: lixiaowei419@163.com; Yang, Jian; Dai, Xiaohu

    2014-07-15

    Highlights: • Earthworm growth biomass and activity decreased with the VF depth. • Earthworm gut microbial communities were dominated by Gammaproteobacteria. • δ{sup 15}N and δ{sup 13}C in earthworms decreased with time, and increased with the VF depth. • Effect of earthworm feeding in enhanced VSS reduction was analyzed quantitatively. • Earthworm feeding had low contribution to the enhanced VSS reduction. - Abstract: Previous studies showed that the presence of earthworm improves treatment performance of vermifilter (VF) for sewage sludge stabilization, but earthworm eco-physiological characteristics and effects in VF were not fully investigated. In this study, earthworm population, enzymatic activity, gut microbial community and stable isotopic abundance were investigated in the VF. Results showed that biomass, average weight, number and alkaline phosphatase activity of the earthworms tended to decrease, while protein content and activities of peroxidase and catalase had an increasing tendency as the VF depth. Earthworm gut microbial communities were dominated by Gammaproteobacteria, and the percentages arrived to 76–92% of the microbial species detected. {sup 15}N and {sup 13}C natural abundance of the earthworms decreased with operation time, and increased as the VF depth. Quantitative analysis using δ{sup 15}N showed that earthworm feeding and earthworm–microorganism interaction were responsible for approximately 21% and 79%, respectively, of the enhanced volatile suspended solid reduction due to the presence of earthworm. The finding provides a quantitative insight into how earthworms influence on sewage sludge stabilization in vermifiltration system.

  6. Study on synthesis of 15N-hydrazine hydrate

    The 15N labeled hydrazine hydrate is a strong reducing agent in the synthesis procedure of stable isotope labeled compounds, and it has been widely used in the isotope-labeled pharmaceutical synthesis. The reaction conditions of 15N labeled hydrazine hydrate were mainly investigated by single-factor design, and the following optimized conditions were obtained: the concentration of available chlorine was 115-120 g/L, the chlorination re- action time was 30∼40 min, the reflux time was 7 min, and the mass ratio of material was m(catalyst) : m (urea) = 1.0 : 10.0, and the yield of 15N labeled hydrazine hydrate was 76.1%, the abundance of 15N was 99.20%. (authors)

  7. Carbon and nitrogen biogeochemistry in the ocean: A study using stable isotope natural abundance

    Rau, G. H.; Desmarais, David J.

    1985-01-01

    Determining the biogeochemical pathways traveled by carbon and nitrogen in the ocean is fundamental to the understanding of how the ocean participates in the cycling of these elements within the biosphere. Because biological production, metabolism, and respiration can significantly alter the natural abundance of C-13 and N-15, these abundances can provide important information about the nature of these biological processes and their variability in the marine environment. The research initially seeks to characterize the spatial and temporal patterns of stable isotope abundances in organic matter, and to relate these abundances to C and N biogeochemical processes within selected areas of the northeastern Pacific Ocean.

  8. Abundant natural gas delays nuclear decision for the Netherlands

    The energy situation in the Netherlands is discussed. A decrease in natural gas reserves and a rise in energy demand will mean a relative decline in the share of natural gas in the economy. The share of primary energy sources in total energy consumption and the development of electricity consumption are shown. Two scenarios for future energy supply are worked out, one assuming cumulative growth and the other considering the case of gradual stabilization. Possible ways of meeting future demand are illustrated and factors to be considered in making a choice, such as the role of nuclear power, are indicated. (UK)

  9. Variability of δ15N in soil and plants at a New Zealand hill country site: correlations with soil chemistry and nutrient inputs

    This study investigated 15N enrichment and nutrient cycling in hill country used for semi-extensive pastoral agriculture, at a site where pre-European seabird breeding occurred. Soil (>15 cm) and plant samples were taken from 18 ridgeline and sideslope transects. Three stock camps (locations which grazing animals frequent) were identified within the study area, two on the ridgeline and one on the sideslope. Soil 15N enrichment was greatest at stock camps, and lowest where stock input was minimal. Soil natural abundance 15N (815N) was therefore an index of stock nutrient inputs. Soil δ15N increased with decreasing C:N ratio, consistent with N loss through volatilisation and/or nitrate leaching from net mineralisation. Plant δ15N from stock camps was lower than its associated soil, implying that 15N enrichment of plant-available N was lower than that of total soil N. However, the correlation between plant δ15N and soil δ15N varied between stock camps, indicating differences in N cycling. Olsen P was higher at stock camps, although again differences were found between stock camps. Total P and N were correlated neither with stock camps nor topography, but were higher than expected from parent material concentrations and literature results, respectively. It is postulated that significant contributions of both elements from former seabird breeding remain in the soil. Copyright (2000) CSIRO Publishing

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

    The 15N 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 15N 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 15N tensors at natural abundance is challenging and this limitation is overcome by improved 1H 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 15N tensors are at least 5 times more sensitive to crystal structure than 13C tensors due to nitrogen’s greater polarizability and larger range of chemical shifts

  11. Abundant Shale Gas Resources: Long-Term Implications for U.S. Natural Gas Markets

    Stephen P. A. Brown; Krupnick, Alan

    2010-01-01

    According to recent assessments, the United States has considerably more recoverable natural gas in shale formations than was previously thought. Such a development raises expectations that U.S. energy consumption will shift toward natural gas. To examine how the apparent abundance of natural gas and projected growth of its use might affect natural gas prices, production, and consumption, we use NEMS-RFF to model a number of scenarios—reflecting different perspectives on natural gas availabil...

  12. FAO/IAEA - interregional training course on the use of 15N in soil science and plant nutrition

    This training manual provides an introduction for the basic methodology and principles of application of the stable isotope 15N. After preliminary remarks on stable isotope terminology fundamentals, experimental problems and methods of quantitative nitrogen determination in soil and plant studies are reported in the main part of the manual. An appendix with a compilation of different parameters such as natural abundance of stable isotopes, selected atomic weights and multiples of them conversion factors of chemical compounds, and much more concludes the manual

  13. Natural Abundance 14C Content of Dibutyl Phthalate (DBP from Three Marine Algae

    Kazuyo Ukai

    2006-11-01

    Full Text Available Abstract: Analysis of the natural abundance 14C content of dibutyl phthalate (DBP from two edible brown algae, Undaria pinnatifida and Laminaria japonica, and a green alga, Ulva sp., revealed that the DBP was naturally produced. The natural abundance 14C content of di-(2-ethylhexyl phthalate (DEHP obtained from the same algae was about 50-80% of the standard sample and the 14C content of the petrochemical (industrial products of DBP and DEHP were below the detection limit.

  14. Method of 15 N analysis by mass-spectrometry on ion implanter MPB-200

    The industrial implanter MPB-200 has been modified to a light-isotopes mass-spectrometer. Mass resolution has been improved by combination of the quadrupole focusing system and a collimator with additional scattering shielding. single beam method has been set up, in which mass-spectra are obtained by scanning magnetic field of the separator. A start-stop control system has been designed to operate automatically the magnet and registration system, from which signals are transferred to a XT/AT computer for saving and processing. The mass - resolution is satisfactory for analysis of light isotopes with mass number A less than 40. A testing measurement has been done with standard samples of natural and enriched 15 N isotope content. Obtained resolution and background condition allowed to achieve a good linear dependence of relative isotope ratio vs. real 15 N abundance in the range from natural (0.365%) to 5.0% with an accuracy of 3% (96% of reliability). Routine 15 N analysis may achieve the 5% - 10% accuracy by 7 - 10 minutes measurement for each sample. The new mass-spectroscopy system is applied in agricultural, biological and environmental studies. (author). 4 refs., 4 figs

  15. Synthesis of 15 N double labelled urea

    Synthesis of double 15 N labelled urea by reacting 15 N - ammonia with elemental sulfur and carbon monoxide in a pressure vessel is presented. 15 NH3 was produced by H15 NO3 reduction with Dewarda alloy in alkaline solution, or by nitric monoxide reduction with hydrogen on metallic manganese. An average yield of 85% tacking into account 15 N - urea and 15 N ammonium sulfate, produced in the same time, and 99% urea purity (checked by I.R. spectroscopy and mass spectrometry) were obtained. (authors)

  16. Use of N Natural Abundance and N Species Concentrations to Assess N-Cycling in Constructed and Natural Coastal Wetlands

    C. Marjorie Aelion

    2010-01-01

    Full Text Available Natural abundance of N stable isotopes used in combination with concentrations may be useful indicators of N-cycling in wetlands. Concentrations and N signatures of NO3−, NH4+, and sediment organic nitrogen (SON were measured in two impacted coastal golf course retention ponds and two natural marshes. Limited NO3− was detected in natural site surface water or pore water, but both isotopic signature and concentrations of NO3− in surface water of impacted sites indicated anthropogenic inputs. In natural sites, NH4+ concentrations were greatest in deeper pore water and least in surface water, suggesting diffusion predominates. The natural sites had greater %SON, and N indicated that the natural sites also had greater NH4+ released from SON mineralization than impacted sites. In NO3−-limited systems, neither concentrations nor N natural abundance was able to provide information on N-cycling, while processes associated with NH4+ were better elucidated by using both concentrations and N natural abundance.

  17. Investigation of the metabolism of colostomized laying hens with 15N-labelled wheat. 6

    Three colostomized laving hens received 40 g 15N-labelled wheat with 20.13 atom-% 15N excess (15N'), 19.18 atom-% 15N'-lysine, 18.17 atom-% 15N'-histidine and 20.43 atom-% 15N'-arginine per day over a period of four days. After having received the same non-labelled feed ration on the following four days, the hens were slaughtered. The incorporation and distribution of 15N' in the total nitrogen and the nitrogen of the basic amino acids was determined in liver, kidneys, muscles, bones and the remaining carcass (excluding blood, digestive tract and genital organs). The quota of nitrogen of natural isotope frequency (14N) of the total 14N of the hens' carcasses was 47% in the muscles, 14% in the bones and 20% in the feathers; the relative 15N' values were 37%, 8% and 1%, resp. The atom-% 15N' in the kidneys was twice as much as in the liver four days after the last 15N' application. The average percentage of the nitrogen in the three basic amino acids of the total nitrogen in the tissues and organs (excluding feathers) is 25% concerning both 14N and 15N'. The 15N' balance revealed that in hen 1 100%, in hen 2 102% and in hen 3 101% of the consumed wheat 15N' were found. (author)

  18. Assessment of Soil Organic Carbon Stability in Agricultural Systems by Using Natural Abundance Signals of Stable Carbon and Nitrogen Isotopes

    Information on the stability and age of soil organic matter (SOM) pools is of vital importance for assessing the impact of soil management and environmental factors on SOM, an important part of the global carbon (C) cycle. The terrestrial soil organic C pool, up to a depth of 1 m, contains about 1500 Pg C (Batjes, 1996). This is about 2.5 times more organic C than the vegetation (650 Pg C) and about twice as much as in the atmosphere (750 Pg C) (Batjes, 1998), but the assessment of the stability and age of SOM using 14C radio carbon technique are expensive. Conen et al. (2008) developed a model to estimate the SOM stability based on the isotopic discrimination of 15N natural abundance by soil micro-organisms and the change in C/N ratio during organic matter decomposition, for steady state, Alpine and permanent grasslands. In the framework of the IAEA funded coordinated research project (CRP) on Soil Quality and Nutrient Management for Sustainable Food Production in Mulch based Cropping Systems in sub-Saharan Africa, research was initiated to use this model in agricultural systems for developing a cost effective and affordable technique for Member States to determine the stability of SOM. As part of this research, soil samples were taken and analysed in four long term field experiments, established on soils with low and high SOM, in Austria and Belgium. The participating institutions are the Austrian Agency for Health and Food Safety (AGES), the University of Natural Resources and Life Sciences in Vienna (BOKU), the University of Leuven (KUL), the Soil Service of Belgium (BDB) and the Centre Wallon de Recherches Agronomiques (CRA-W)

  19. The Titan 14N/ 15N and 12C/ 13C isotopic ratios in HCN from Cassini/CIRS

    Vinatier, Sandrine; Bézard, Bruno; Nixon, Conor A.

    2007-11-01

    We report the detection of H 13CN and HC 15N in mid-infrared spectra recorded by the Composite Infrared Spectrometer (CIRS) aboard Cassini, along with the determination of the 12C/ 13C and 14N/ 15N isotopic ratios. We analyzed two sets of limb spectra recorded near 13-15° S (Tb flyby) and 83° N (T4 flyby) at 0.5 cm -1 resolution. The spectral range 1210-1310 cm -1 was used to retrieve the temperature profile in the range 145-490 km at 13° S and 165-300 km at 83° N. These two temperature profiles were then incorporated in the atmospheric model to retrieve the abundance profile of H 12C 14N, H 13CN and HC 15N from their bands at 713, 706 and 711 cm -1, respectively. The HCN abundance profile was retrieved in the range 90-460 km at 15° S and 165-305 km at 83° N. There is no evidence for vertical variations of the isotopic ratios. Constraining the isotopic abundance profiles to be proportional to the HCN one, we find C12/C13=89-18+22 at 15° S, and 68-12+16 at 83° N, two values that are statistically consistent. A combination of these results yields a 12C/ 13C value equal to 75±12. This global result, as well as the 15° S one, envelop the value in Titan's methane ( 82.3±1) [Niemann, H.B., and 17 colleagues, 2005. Nature 438, 779-784] measured at 10° S and is slightly lower than the terrestrial inorganic standard value (89). The 14N/ 15N isotopic ratio is found equal to 56-13+16 at 15° S and 56-9+10 at 83° N. Combining the two values yields 14N/ 15N = 56 ± 8, which corresponds to an enrichment in 15N of about 4.9 compared with the terrestrial ratio. These results agree with the values obtained from previous ground-based millimeter observations [Hidayat, T., Marten, A., Bézard, B., Gautier, D., Owen, T., Matthews, H.E., Paubert, G., 1997. Icarus 126, 170-182; Marten, A., Hidayat, T., Biraud, Y., Moreno, R., 2002. Icarus 158, 532-544]. The 15N/ 14N ratio found in HCN is ˜3 times higher than in N 2 [Niemann, H.B., and 17 colleagues, 2005. Nature 438, 779

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

    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.

  1. Association between patterns in agricultural landscapes and the abundance of wheat aphids and their natural enemies

    Jun-He Liu

    2013-12-01

    Full Text Available Effect of different landscape patterns on insect distribution and diversity was determined by studying wheat fields in complex and simple agricultural landscapes. We studied the influence of simple and complex agricultural landscapes on wheat aphids and their natural enemies in terms of the time of migration, abundance, population growth rate of the aphids and parasitoid abundance. The results indicate that the diversity of natural enemies is greater in the complex agricultural landscape and the effect of natural enemies on the abundance of wheat aphids was greater in the complex non-crop habitat. Wheat aphid hyperparasitoid populations differed in different agricultural landscapes with a greater number of parasites in complex agricultural landscapes. Resident times of predatory natural enemies differ in simple and complex agricultural landscapes. The number and types of predatory natural enemies are higher in complex than simple agricultural landscapes. Aphid population growth rates and the maximum population densities of wheat aphids differed significantly in simple and complex landscapes. Maximum population densities of different wheat aphids were very different in simple and complex landscape structures. The population growth rates and maximum population densities of the different predatory natural enemies and hyperparasitoids differed greatly.

  2. A Computational Framework for High-Throughput Isotopic Natural Abundance Correction of Omics-Level Ultra-High Resolution FT-MS Datasets

    William J. Carreer

    2013-09-01

    Full Text Available New metabolomics applications of ultra-high resolution and accuracy mass spectrometry can provide thousands of detectable isotopologues, with the number of potentially detectable isotopologues increasing exponentially with the number of stable isotopes used in newer isotope tracing methods like stable isotope-resolved metabolomics (SIRM experiments. This huge increase in usable data requires software capable of correcting the large number of isotopologue peaks resulting from SIRM experiments in a timely manner. We describe the design of a new algorithm and software system capable of handling these high volumes of data, while including quality control methods for maintaining data quality. We validate this new algorithm against a previous single isotope correction algorithm in a two-step cross-validation. Next, we demonstrate the algorithm and correct for the effects of natural abundance for both 13C and 15N isotopes on a set of raw isotopologue intensities of UDP-N-acetyl-D-glucosamine derived from a 13C/15N-tracing experiment. Finally, we demonstrate the algorithm on a full omics-level dataset.

  3. Resolution of the 15N balance enigma?

    The enigma of soil nitrogen balance sheets has been discussed for over 40 years. Many reasons have been considered for the incomplete recovery of 15N applied to soils, including sampling uncertainty, gaseous N losses from plants, and entrapment of soil gases. The entrapment of soil gases has been well documented for rice paddy and marshy soils but little or no work appears to have been done to determine entrapment in drained pasture soils. In this study 15N-labelled nitrate was applied to a soil core in a gas-tight glovebox. Water was applied, inducing drainage, which was immediately collected. Dinitrogen and N-2 were determined in the flux through the soil surface, and in the gases released into the glovebox as a result of irrigation or physical destruction of the core. Other components of the N balance were also measured, including soil inorganic-N and organic-N. Quantitative recovery of the applied 15N was achieved when the experiment was terminated 484 h after the 15N-labelled material was applied. Nearly 23% of the 15N was recovered in the glovebox atmosphere as N2 and N2O due to diffusion from the base of the soil core, convective flow after irrigation, and destructive soil sampling. This 15N would normally be unaccounted for using the sampling methodology typically employed in 15N recovery experiments. Copyright (2001) CSIRO Publishing

  4. Relationship between the abundance of aphids and their natural enemies in cereal fields and landscape composition

    Diab Al Hassan

    2013-03-01

    Full Text Available We investigated, over the course of two years, the association between the abundance of aphids and their natural carabid enemies and landscape, which may help in the development of effective strategies for reducing the incidence of aphid outbreaks in agricultural crops. This was undertaken in 12 wheat and 12 maize fields each year in an agricultural landscape in western France. Our study area was characterized by hedgerows surrounding arable fields and permanent grassland. Some areas have not changed much for several decades, while field enlargement and removal of hedges occurred in some areas following agricultural intensification. This paper aims to determine if the abundance of aphids in crops (either directly, or indirectly via their natural enemies is associated with the landscape around fields and if so, is it dependent on the landscape scale considered. We observed that the abundance of aphids in fields was associated with landscape composition at a large scale (500 m and 800 m. There was a positive correlation between the abundance of aphids and the proportion of the area under woodland and grassland at these scales. There was a negative correlation between the abundance of carabids and the proportion of grassland and hedgerow around crop fields. The species richness of carabids was positively correlated with the proportion of hedgerows. We found that the abundance of aphids in wheat fields was negatively and in maize fields positively associated with the proportion under grass strips. At a large scale carabid abundance in both types of culture was positively correlated with the proportion under grass strips.

  5. Synthesis and NMR characterization of (15N)taurine [2-(15N)aminoethanesulfonic acid

    The title compound was prepared in three steps with 55% overall yield starting from potassium (15N)phthalimide. The synthetic route involved reaction with 1,2-dibromoethane, hydrolysis of the resulting N-(2-bromoethyl) (15N)phthalimide with HBr and treatment of the 2-bromoethyl(15N)amine thus formed with sodium sulphite. The product was characterized by 13C, 1H and 15N NMR spectroscopy. The absolute coupling constants of 15N with the 13C nuclei and the non-exchanging protons were determined and an unambiguous assignment of the proton signals obtained. (author)

  6. Global modeling of the 15N216O line positions within the framework of the polyad model of effective Hamiltonian and a room temperature 15N216O line list

    Tashkun, S. A.; Perevalov, V. I.; Liu, A.-W.; Hu, S.-M.

    2016-05-01

    The global modeling of 15N216O line positions in the 4-12,516 cm-1 region has been performed using the polyad model of effective Hamiltonian. The effective Hamiltonian parameters were fitted to the line positions collected from an exhaustive review of the literature. The dimensionless weighted standard deviation of the fit is 1.31. The fitted set of 109 parameters allowed reproducing more than 18,000 measured line positions with an RMS value of 0.001 cm-1. A line list was calculated for a reference temperature 296 K, natural abundance (1.32×10-5), and an intensity cutoff 10-30 cm/molecule. The line list is based on the fitted set of the effective Hamiltonian parameters for 15N216O obtained in this work and the effective dipole moment parameters of the 15N216O and 14N216O isotopologues. Accurate values of the 15N216O total partition function are also given.

  7. Natural Genetic Variation Influences Protein Abundances in C. elegans Developmental Signalling Pathways.

    Kapil Dev Singh

    Full Text Available Complex traits, including common disease-related traits, are affected by many different genes that function in multiple pathways and networks. The apoptosis, MAPK, Notch, and Wnt signalling pathways play important roles in development and disease progression. At the moment we have a poor understanding of how allelic variation affects gene expression in these pathways at the level of translation. Here we report the effect of natural genetic variation on transcript and protein abundance involved in developmental signalling pathways in Caenorhabditis elegans. We used selected reaction monitoring to analyse proteins from the abovementioned four pathways in a set of recombinant inbred lines (RILs generated from the wild-type strains N2 (Bristol and CB4856 (Hawaii to enable quantitative trait locus (QTL mapping. About half of the cases from the 44 genes tested showed a statistically significant change in protein abundance between various strains, most of these were however very weak (below 1.3-fold change. We detected a distant QTL on the left arm of chromosome II that affected protein abundance of the phosphatidylserine receptor protein PSR-1, and two separate QTLs that influenced embryonic and ionizing radiation-induced apoptosis on chromosome IV. Our results demonstrate that natural variation in C. elegans is sufficient to cause significant changes in signalling pathways both at the gene expression (transcript and protein abundance and phenotypic levels.

  8. High-resolution NMR of hydrogen in organic solids by DNP enhanced natural abundance deuterium spectroscopy

    Rossini, Aaron J.; Schlagnitweit, Judith; Lesage, Anne; Emsley, Lyndon

    2015-10-01

    We demonstrate that high field (9.4 T) dynamic nuclear polarization (DNP) at cryogenic (∼100 K) sample temperatures enables the rapid acquisition of natural abundance 1H-2H cross-polarization magic angle spinning (CPMAS) solid-state NMR spectra of organic solids. Spectra were obtained by impregnating substrates with a solution of the stable DNP polarizing agent TEKPol in tetrachloroethane. Tetrachloroethane is a non-solvent for the solids, and the unmodified substrates are then polarized through spin diffusion. High quality natural abundance 2H CPMAS spectra of histidine hydrochloride monohydrate, glycylglycine and theophylline were acquired in less than 2 h, providing direct access to hydrogen chemical shifts and quadrupolar couplings. The spectral resolution of the 2H solid-state NMR spectra is comparable to that of 1H spectra obtained with state of the art homonuclear decoupling techniques.

  9. On the nature of sn stars. I. A detailed abundance study

    Saffe, C.; H. Levato

    2014-01-01

    The sn stars present sharp Balmer lines, sharp metallic lines and broad coreless He I lines. Initially Abt & Levato proposed a shell-like nature to explain the sn stars, although this scenario was subsequently questioned. We aim to derive abundances for a sample of 9 stars, including sn and non-sn stars, to determine the possible relation between sn and CP stars. We analysed the photospheric chemical composition of sn stars and show that approximately 40% of them display chemical peculiaritie...

  10. Determination of lithium isotopes at natural abundance levels by atomic absorption spectrometry

    Meier, A.L.

    1982-01-01

    The relationships of the absorption of 6Li and 7Li hollow cathode lamp emissions are used to determine lithium isotopic composition in the natural abundance range of geologic materials. Absorption was found to have a nonlinear dependence upon total lithium concentration and isotopic composition. A method using nonlinear equations to describe the relationship of the absorption of 6Li and 7Li lamp radiation is proposed as a means of calculating isotopic composition that is independent of total lithium concentration.

  11. Abundance, Disposal Hypsiboas Espaciale lanciformis Natural History (Anura: Hylidae) southwest of the Venezuelan Andes

    Hypsiboas lanciformis is a tree frog belonging to the albopunctatus group. Its distribution ranges from Bolivia, Brazil, Peru to Colombia and Venezuela. We studied the status of a population inhabiting the realms property of Complejo Uribante-Caparo, CORPOELEC, in Tachira state (southwestern Andean Venezuela), by monitoring their call and visual detection across transects, gathering information on their abundance; available space, and other natural history accounts. The abundance decreases as the dry season progresses, while individuals show an aggregate spatial arrangement. Individuals were vocalizing at the edges of secondary forest adjacent to disturbed areas. This species is sympatric with the hylids Hypsiboas pugnax and Scinax manriquei. Some individuals revealed the presence of ectoparasites and endoparasites that might be affecting the species survivalship.

  12. 15N in biological nitrogen fixation studies

    A bibliography with 298 references on the use of the stable nitrogen isotope 15N in the research on the biological fixation of dinitrogen is presented. The literature pertaining to this bibliography covers the period from 1975 to the middle of 1985. (author)

  13. 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

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

    during the monsoon than the pre-monsoon. Conversely, during the pre-monsoon, monosaccharide composition did not vary much and was mostly dominated by glucose. Monosaccharide abundance and ratios suggest that organic matter was subjected to extensive...

  14. Measuring Long-Lived ^{13}C-Singlet State Lifetimes at Natural Abundance

    Claytor, Kevin E; Feng, Yesu; Warren, Warren

    2013-01-01

    Long-lived singlet states hold the potential to drastically extend the lifetime of hyperpolarization in molecular tracers for in-vivo magnetic resonance imaging (MRI). Such long lived hyperpolarization can be used for elucidation of fundamental metabolic pathways, early diagnosis, and optimization of clinical tests for new medication. All previous measurements of 13C singlet state lifetimes rely on costly and time consuming syntheses of 13C labeled compounds. Here we show that it is possible to determine 13C singlet state lifetimes by detecting the naturally abundant doubly-labeled species. This approach allows for rapid and low cost screening of potential molecular biomarkers bearing long-lived singlet states.

  15. Species richness and relative abundance of birds in natural and anthropogenic fragments of Brazilian Atlantic forest

    Luiz dos Anjos

    2004-06-01

    Full Text Available Bird communities were studied in two types of fragmented habitat of Atlantic forest in the State of Paraná, southern Brazil; one consisted of forest fragments that were created as a result of human activities (forest remnants, the other consisted of a set of naturally occurring forest fragments (forest patches. Using quantitative data obtained by the point counts method in 3 forest patches and 3 forest remnants during one year, species richness and relative abundance were compared in those habitats, considering species groups according to their general feeding habits. Insectivores, omnivores, and frugivores presented similar general tendencies in both habitats (decrease of species number with decreasing size and increasing isolation of forest fragment. However, these tendencies were different, when considering the relative abundance data: the trunk insectivores presented the highest value in the smallest patch while the lowest relative abundance was in the smallest remnant. In the naturally fragmented landscape, time permitted that the loss of some species of trunk insectivores be compensated for the increase in abundance of other species. In contrast, the remnants essentially represented newly formed islands that are not yet at equilibrium and where future species losses would make them similar to the patches.Comunidades de aves foram estudadas em duas regiões fragmentadas de floresta Atlântica no Estado do Paraná, sul do Brasil; uma região é constituída de fragmentos florestais que foram criados como resultado de atividades humanas (remanescentes florestais e a outra de um conjunto de fragmentos florestais naturais (manchas de floresta. Usando dados quantitativos (o método de contagens pontuais previamente obtidos em 3 manchas de floresta e em 3 remanescentes florestais durante um ano, a riqueza e a abundância relativa de aves foram comparadas naqueles habitats considerando as espécies pelos seus hábitos alimentares. Inset

  16. 15N2 incorporation by rhizosphere soil

    Heterotrophic nitrogen fixation by rhizosphere soil samples from 20 rice cultivars grown under uniform field conditions was estimated employing 15N-tracer technique. Rhizosphere soil samples from different rice cultivars showed striking differences with regard to their ability to incorporate 15N2. Rhizosphere samples from rice straw-amended (3 and 6 tons/ha) soil exhibited more pronounced nitrogen-fixing activity than the samples form unamended soil; while the activity of the rhizosphere samples from soil receiving combined nitrogen (40 and 80 kg N/ha) was relatively low. However, the inhibitory effect of combined nitrogen was not expressed in the presence of rice straw at 6 tons/ha. Results suggest that plant variety, application of combined nitrogen and organic matter influence the rhizosphere nitrogen fixation. (orig.)

  17. Synthesis of 15N labeled glyphosate

    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 15N labeled glyphosate. The 15N-herbicide was undertaken by phosphometilation with the phosphit dialquil and 15N-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)

  18. Utilization of natural variations in the abundance of nitrogen-15 as a tracer in hydrogeology - Initial results

    Nitrogen compounds dissolved in natural waters exhibit considerable variations in nitrogen-15 content (more than 10 per mille). The authors describe briefly the analytical techniques used in measuring δ15N, the main features of the isotopic cycle of nitrogen and the results obtained so far. A simplified model of the nitrogen cycle and its isotopic implications is presented; with this model one can deduce from a number of observed variations the physical or biological mechanism (or mechanisms) involved. Isotopic studies of nitrogen may be a useful additional tool for detecting and interpreting certain forms of pollution. (author)

  19. Carbon dynamics in corn-soybean sequences as estimated from natural carbon-13 abundance

    Carbon flow in terrestrial ecosystems regulates partitioning between soil organic C (SOC) and atmospheric CO2. Our objectives were to assess SOC dynamics using natural 13C abundance in corn (Zea mays L., a C4 species)-soybean [Glycine max (L.) Merr., a C3 species] sequences. Fifteen treatments of continuous corn, continuous soybean, various sequences of corn and soybean, and fallow were initiated in 1981 at Lamberton, MN, on a Webster clay loam (fine-loamy, mixed, mesic Typic Haplaquoll). In 1991, soil and aboveground shoot samples from all treatments were analyzed for total organic C and delta 13C. Carbon inputs, delta 13C, and SOC were integrated into a two-pool model to evaluate C dynamics of corn and soybean. Total SOC was similar across all treatments after 10 yr; however, differences in soil delta 13C occurred between continuous corn (delta 13C = -17.2 per thous and) and continuous soybean (delta 13C = -18.2 per thousand). Modeled C dynamics showed SOC decay rates of 0.011 yr-1 for C4-derived C and 0.007 yr-1 for C3-derived C, and humification rates of 0.16 yr-1 for corn and 0.11 yr-1 for soybean. Decay and humification rates were slightly lower than those found in other Corn Belt studies. Levels of SOC were predicted to decline an additional 7 to 18% with current C inputs from either corn or soybean, respectively. Annual C additions required for SOC maintenance averaged 5.6 Mg C ha-1, 1.4 to 2.1 times greater than previously reported estimates. Controlled variation in natural 13C abundance in corn-soybean rotations during a 10-yr period adequately traced C dynamics

  20. 15N-labed glycine synthesis

    Claudinéia R. O. Tavares; José A. Bendassolli; Fernando Coelho; Carlos R. Sant Ana Filho; Clelber V. Prestes

    2006-01-01

    This work describes a method for 15N-isotope-labeled glycine synthesis, as well as details about a recovery line for nitrogen residues. To that effect, amination of alpha-haloacids was performed, using carboxylic chloroacetic acid and labeled aqueous ammonia (15NH3). Special care was taken to avoid possible 15NH3 losses, since its production cost is high. In that respect, although the purchase cost of the 13N-labeled compound (radioactive) is lower, the stable tracer produced constitutes an i...

  1. EVALUACIÓN DEL MÉTODO DE LA ABUNDANCIA NATURAL 15N EN LA ESTIMACIÓN DEL EFECTO DE LA TRANSFERENCIA DE NITRÓGENO DE LA LEGUMINOSA Canavalia ensiformis (CANAVALIA) SOBRE LA NUTRICIÓN NITROGENADA DE LA PLANTA ASOCIADA Musa acuminata (PLÁTANO)

    Natacha Motisi; Tournebize, R.; J. Sierra

    2007-01-01

    La asociación de una leguminosa con un cultivo de cosecha ha demostrado ser una práctica eficaz para aportar nitrógeno (N) al sistema suelo-planta y así reducir el uso de fertilizantes. El objetivo de este estudio fue analizar la utilidad del método de la abundancia natural 15N para evaluar ese aporte. Se realizó un ensayo en macetas bajo condiciones de invernadero con la asociación canavalia-plátano, con el objeto de estimar la contribución de los exudados de la leguminosa y del N producto d...

  2. Sources and transformations of N in reclaimed coastal tidelands: evidence from soil δ15N data

    Kwak, Jin-Hyeob; Choi, Woo-Jung; Lim, Sang-Sun; Lee, Seung-Heon; Lee, Sang-Mo; Chang, Scott X.; Jung, Jae-Woon; Yoon, Kwang-Sik; Choi, Soo-Myung

    2008-01-01

    Electrical conductivity of saturated soil extracts (ECe) in three reclaimed tideland (RTL) soils on the west coast of Korea decreased with time since reclamation, indicating natural desalinization through leaching of salts by precipitation water. Soil N concentration increased with decreasing ECe. With the increase in soil N concentration, the δ15N decreased, likely caused by the input of 15N-depleted N sources. As N2-fixing plant species were found in the oldest RTL, atmospheric N2 fixation likely contributed to the increase in soil N concentration in the oldest RTL. Negative δ15N (-7.1 to -2.0‰) of total inorganic N (NH4 ++NO3 -) and published data on N deposition near the study area indicate that atmospheric N deposition might be another source of N in the RTLs. Meanwhile, the consistently negative δ15N of soil NO3 - excluded N input from chemical fertilizer through groundwater flow as a potential N source, since NO3 - in groundwater generally have a positive δ15N. The patterns of δ15N of NH4 + (+2.3 to +5.1‰) and NO3 - (-9.2 to -5.0‰) suggested that nitrification was an active process that caused 15N enrichment in NH4 + but denitrification was probably minimal which would otherwise have caused 15N enrichment in NO3 -. A quantitative approach on N budget would provide a better understanding of soil N dynamics in the studied RTLs.

  3. Utilization of 15N-labelled urea in laying hens. 8

    3 colostomized laying hybrids received orally with a conventional ration 1% urea with 96.06 atom-% 15N excess (15N') over a period of 6 days. In the period of the experiment every hen consumed 2.87 g 15N'. After another 2 days, on which they received conventional feed urea, the animals were butchered. 15N' was determined in the total N and in 15 amino acids of the oviduct. Of the 15 amino acids the labelling of glutamic acid, glycine and serine was highest and on average amounted to 0.80, 0.66 and 0.67 atom-% 15N', resp. In lysine and arginine only 0.10 and 0.11 atom-% 15N' could be detected. The amino acid N with natural isotopic frequency amounted to a quarter for the basic amino acids, a tenth for the branched chain ones and for the non-essential ones (glutamic acid, aspartic acid, serine, glycine, alanine, proline) a third of the total oviduct 14N. The average quota of 15N' is only 3.6%, that of the branched chain amino acids 4.5 and that of the non-essential ones 21.1%. Consequently, the 15N' of the urea is mainly used for the synthesis of the non-essential amino acids of the oviduct. (author)

  4. Measuring denitrification after grassland renewal and grassland conversion to cropland by using the 15N gas-flux method

    Buchen, Caroline; Eschenbach, Wolfram; Flessa, Heinz; Giesemann, Anette; Lewicka-Szczebak, Dominika; Well, Reinhard

    2015-04-01

    Denitrification, the reduction of oxidized forms of inorganic N to N2O and N2 is an important pathway of gaseous nitrogen losses. Measuring denitrification, especially the reduction of N2O to N2, expressed in the product ratio (N2O/(N2O + N2)), is rather difficult and hence rarely performed under field conditions. But using the 15N gas-flux method allows determining N transformation processes in their natural environment. In order to develop effective climate mitigation strategies understanding the N2O source is essential. We used the 15N gas-flux method to determine N2O and N2 emissions following grassland renewal and conversion techniques. Therefore we selected three different treatments: control (C), mechanical grassland renovation (GR) (autumn 2013) and grassland conversion to maize (GM) (spring 2014) from field plot trials on two different sites (Histic Gleysoil and Plaggic Anthrosol) near Oldenburg, Lower Saxony, Germany. We applied 15N labeled KNO3- (60 atom. % 15N) at a rate equivalent to common farming practices (150 kg N*ha-1) using needle injection of fertilizer solution in three different depths (10 cm, 15 cm, 20 cm) for homogeneous soil labeling up to 30 cm in microplots. During the first 10 days after application (May 2014) gas flux measurements from closed chambers were performed every second day and then weekly following a period of 8 weeks. Gas samples were analyzed for δ15N of N2 and N2O by IRMS according to Lewicka-Szczebak et al. (2013). Concentration and 15N enrichment of NO3- in soil water was determined on weekly samples using the SPIN-MAS technique (Stange et al. 2007). Fluxes of N2 and N2O evolved from the 15N labeled soil nitrogen pool were calculated using the equations of Spott et al. (2006). Peak events of N2 and N2O emissions occurred during the first 10 days of measurement, showing differences in soil types, as well as treatment variations. N2 fluxes up to 178 g*ha-1*day-1 and N2O fluxes up to 280 g*ha-1*day-1 were measured on the

  5. Effect of protein restriction on (15)N transfer from dietary [(15)N]alanine and [(15)N]Spirulina platensis into urea.

    Hamadeh, M J; Hoffer, L J

    2001-08-01

    Six normal men consumed a mixed test meal while adapted to high (1.5 g. kg(-1) x day(-1)) and low (0.3 g. kg(-1) x day(-1)) protein intakes. They completed this protocol twice: when the test meals included 3 mg/kg of [(15)N]alanine ([(15)N]Ala) and when they included 30 mg/kg of intrinsically labeled [(15)N]Spirulina platensis ([(15)N]SPI). Six subjects with insulin-dependent diabetes mellitus (IDDM) receiving conventional insulin therapy consumed the test meal with added [(15)N]Ala while adapted to their customary high-protein diet. Protein restriction increased serum alanine, glycine, glutamine, and methionine concentrations and reduced those of leucine. Whether the previous diet was high or low in protein, there was a similar increase in serum alanine, methionine, and branched-chain amino acid concentrations after the test meal and a similar pattern of (15)N enrichment in serum amino acids for a given tracer. When [(15)N]Ala was included in the test meal, (15)N appeared rapidly in serum alanine and glutamine, to a minor degree in leucine and isoleucine, and not at all in other circulating amino acids. With [(15)N]SPI, there was a slow appearance of the label in all serum amino acids analyzed. Despite the different serum amino acid labeling, protein restriction reduced the postmeal transfer of dietary (15)N in [(15)N]Ala or [(15)N]SPI into [(15)N]urea by similar amounts (38 and 43%, respectively, not significant). The response of the subjects with IDDM was similar to that of the normal subjects. Information about adaptive reductions in dietary amino acid catabolism obtained by adding [(15)N]Ala to a test meal appears to be equivalent to that obtained using an intrinsically labeled protein tracer. PMID:11440912

  6. Effect of applying wheat stubble on preservation and utilization of n-fertilizer by 15N trace technique

    By using 15N trace technique, the effect of applying wheat stubble on the preservation and utilization rate of 15N- ammonium sulphate have been studied. The abundance of (15NH4)2SO4 fertilizer was 8.92%. After three years pot test and field plot test, the results showed that the yields with '15N+mulching' and '15N+incorporating' treated were increased by 5.4∼30.0% for spring wheat and millet(pot test), and 18∼23% for winter wheat and summer corn(field plot test), as compared with only '15N' treatment. The results of 15N-fertilizer labelled tests showed that the utilization rates of 15N-fertilizer treated by '15N+mulching' for cropping seasons were 57.8%, 65.8%, 36.6% and 8.5% respectively. These were increased 3.7%, 10.2%, 21.5% and 2.8% as compared with only '15N' treatment. Comparing with only '15N'treatment, the N leached off by percolation water was decreasing 50%, the loss of N caused by volatilization was decreasing 30.3% and the N in humus was increasing 21.1%. All of these proved that the applying of wheat stubble in different mode would adjust and control the activation of microbe in the soil, and the preservation and utilization rate of fertilizer in the soul would be increased

  7. The magnitude of spatial and temporal variation in δ15N and δ13C differs between taxonomic groups: Implications for food web studies

    Hyndes, Glenn A.; Hanson, Christine E.; Vanderklift, Mathew A.

    2013-03-01

    Understanding variability in stable isotope abundance is essential for effective hypothesis testing and evaluating food sources, trophic levels and food web structure. The magnitude and sources of variability are likely to differ among taxonomic and functional groups. We aimed to quantify variability of δ13C and δ15N for 16 species representing seven distinct taxonomic groups of benthic invertebrates and autotrophs in a marine ecosystem. We quantified the magnitude of variability among individuals or shoots separated by metres, among eight sites separated by kilometres, and between two survey occasions separated by months. δ13C varied by as much as 7‰ for primary producers, 4‰ for consumers, while δ15N varied by as much as 9‰ and 2‰ respectively. Variation in δ15N of seagrass was largely accounted for by differences among sites, while variation in δ13C was mainly attributable to shoots collected a few metres apart. Compared to seagrasses, variation in macroalgae was mainly explained by differences between the two survey occasions for δ15N and among individuals collected a few metres apart for δ13C. Variation was generally lower for consumers and typically explained by differences among individuals for δ15N but displayed inconsistent patterns for δ13C. Dual isotope Bayesian mixing models showed that the potential contributions of food sources for herbivorous consumers varied among sites and between survey occasions, and also that there was high variability or uncertainty in the contributions of sources within sites. The relative consistency in the main sources of variation among broad taxonomic groups in autotrophs suggests that aspects of physiology that are phylogenetically conserved might be important influences on variation in natural abundances of stable isotopes. In comparison, the sources of variability were less consistent within and among broad consumer groups, suggesting complex interactions between consumers and their food sources.

  8. The study of diet and trophic relationships through natural abundance 13C

    Measurement of the natural abundances of stable carbon atoms (δ13C) is a powerful way to study the dietary organization of an entire ecosystem. In some cases, it is often the only tool available for distinguishing and tracing different food sources. However, like all methods, it has certain limitations; care must always be taken in designing the experiment and in interpreting the results. This chapter covers all of these aspects of the method. Section 1 gives examples of specific areas in which the technique is valuable, a general discussion of its limitations and how to work around them, and finally some examples of particular studies that are used to illustrate the different procedures. Section 2 enumerates the various factors important for both experimental design and for interpretation of results. Section 3 describes the particular steps necessary to obtain, process, and preserve samples. General techniques and principles are given that can be applied to all ecosystems. Specific methods for marine plankton illustrate how the principles can be applied

  9. Calibration of an elastic recoil setup for D/H-ratios close to natural abundance

    Nominally Anhydrous Minerals (NAM) in the Earth’s mantle contain trace amounts of hydrogen, as a result of the NAM’s ability to incorporate hydroxyl ions. The isotopic composition of these hydrogen reservoirs is for the Earth’s crust, well characterized. The knowledge of the isotopic composition of the Earth’s interior on the other hand is limited. It is believed that the hydrogen composition in the interior is isotopically heterogeneous and that there may exist several reservoirs of hydrogen, characterized by different deuterium/hydrogen-ratios. Characterization of these hydrogen reservoirs can provide valuable information about the mass transport of hydrogen during the evolution of the planet. In this work we present a variant of the proton–proton scattering technique with which we are capable of performing simultaneous measurements of deuterium and hydrogen. The method has been tested with a 2.9 MeV deuteron beam on a polyethylene standard, with D/H ratio close to the natural abundance, and on a thin sample of Muscovite with a hydrogen concentration of 4800 wt-ppm. This is followed by a discussion about limitations and capabilities of the technique

  10. Deuterium contents in animal organisms in presence of natural abundance and depleted deuterium aqueous media

    Deuterium,the stable heavy isotope of hydrogen, when more abundant than the natural values (i.e. 144 ppm), as in heavy water, induces significant alterations in the anatomy and physiology of animal or vegetal cells. Such alterations eventually entail the death of the cell. On the other hand some products with depleted deuterium have antagonistic effects due to deuterium removal from the cells. The paper reports results of measurements of deuterium concentration in various biological samples in studies about distribution of deuterium depleted agents in organisms. The biological samples studied came from a lot of individuals fed in a regime of depleted deuterium. The mass spectrometric analyses of these biological samples showed that dispersion of deuterium depleted agents inside the organisms is determined by several endo- and exogenous factors. The paper describes the specific procedures of sampling the biological materials destined to isotopic analyses, the extraction of water in vacuum, the methods of deuterium concentration determination and finally presents a discussion of the results reported

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

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

    2016-08-01

    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. PMID:27359161

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

    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.

  13. Elevated Bacterial Abundance in Laboratory-Grown and Naturally Occurring Frost Flowers Under Late Winter Conditions

    Bowman, J. S.; Deming, J. W.

    2009-12-01

    Sea ice has been identified as an important microbial habitat, with bacteria and other microbes concentrated in the brine inclusions between ice crystals. Frost flowers, thought to draw brine from underlying sea ice, have not been characterized from a microbial standpoint. To test whether frost flowers serve as an upward vector of bacteria contained within sea ice brines we grew frost flowers in a freezer laboratory (air temperature of -21°C) from saline water spiked with the mesophilic (and thus passive under experimental conditions) bacterium Halomonas pacifica. Salinity of melted samples was measured and bacterial abundance determined by epifluorescent microscopy. Bacterial counts scaled to ice-melt volume averaged 2.82 x 106 ml-1 for frost flowers, compared to 9.47 x 105 ml-1 for underlying ice (3 x higher). Bacterial counts also correlated significantly with salinity (maximum value of 62.5 psu) for frost flowers, brine skim, and ice (df = 17, r = 0.59, p < 0.0001). Segregation coefficients were calculated to describe the efficiency of transport of both cells and salt from the starting solution into frost flowers. From these coefficients an enrichment index was calculated to test for bacterial concentration into frost flowers at a different rate than salt. Analysis with a Student’s T-test (df = 24, t = 0.306, p = .76) indicated that cells and salt were not transported into frost flowers with a significantly different efficiency. To test these findings in the field we then collected frost flowers (and related samples) from new sea ice near Barrow, Alaska in April 2009. Bacterial counts were significantly elevated (again, a 3-fold increase) in natural frost flowers (mean = 2.73 x 105 ml-1) compared to underlying sea ice (mean = 8.46 x 104 cells ml-1). For all field samples collected (frost flowers, underlying brine skim and sea ice, as well as snow), bacterial abundance correlated significantly with salinity (maximum value 124 psu, df = 40, r = 0.60, p < 0

  14. Influence of niche differentiation on the abundance of methanogenic archaea and methane production potential in natural wetland ecosystems across China

    D. Liu; Ding, W.; Jia, Z; Cai, Z.

    2010-01-01

    Methane (CH4) emissions from natural wetland ecosystems exhibit large spatial variability. To understand the underlying factors that induce differences in CH4 emissions from natural wetlands around China, we measured the CH4 production potential and the abundance of methanogenic archaea in vertical profile soils sampled from the Poyang wetland in the subtropical zone, the Hongze wetland in the warm temperate zone, the Sanjia...

  15. Natural abundance deuterium nuclear magnetic resonance spectroscopy: Study of the biosynthesis of monoterpenes

    Deuterium NMR spectroscopy at natural abundance (D NMR-na) is a new technique for exploring the biosynthesis of small molecules such as monoterpenes. The analysis of relative site-specific deuterium integration values is an effective means of measuring isotope effects, and examining the regio- and stereochemistry of biosynthetic reactions. The deuterium integration values of linalyl acetate and limonene isolated from the same source were consistent and showed that proton abstraction from the postulated α-terpinyl cation intermediate to form limonene is regioselective from the methyl derived from the Cs methyl of the precursor, geranyl diphosphate. This regiochemistry was observed in limonene samples from different sources and the measured primary kinetic isotope effect ranged from 0.25 to in excess of 100 (no deuterium was removed within experimental error). Various α- and β-pinene samples were isolated and D NMR-na analysis showed evidence of isotopically sensitive partitioning of the pinylcation in the formation of these products. This spectral analysis supported published radiolabeling studies but did not require synthesis of substrates or enzyme purification. The formation of 3-carene occurs without isomerization of the double bond which was previously postulated. The olefinic deuterium of the bicyclic compound was traced to the depleted deuterium at C2 of isopentyl diphosphate by D NMR-na data and this supported unpublished radiolabeling studies. Study of irregular monoterpenes, chrysanthemyl acetate and lyratyl acetate, showed partitioning of dimethylallyl diphosphate (DMAPP) by chrysanthemyl cyclase. The α-secondary kinetic isotope effect of 1.06-1.12, obtained from relative deuterium integration values, suggested that SN1 ionization of one molecule of DMAPP is the first step in the condensation reaction

  16. Estimation of natural mortality coefficient from fish abundance and catch data using Virtual Population Analysis (VPA)

    Wang, Yingbin; Liu, Qun; Wang, Yanjun

    2007-01-01

    Natural mortality coefficient ( M) was estimated from fish abundance ( N) and catch ( C) data using a Virtual Population Analysis (VPA) model. Monte Carlo simulations were used to evaluate the impact of different error distributions for the simulated data on the estimates of M. Among the four error structures (normal, lognormal, Poisson and gamma), simulations of normally distributed errors produced the most viable estimates for M, with the lowest relative estimation errors (REEs) and median mean absolute deviations (MADs) for the ratio of the true to the estimated Ms. In contrast, the lognormal distribution had the largest REE value. Errors with different coefficients of variation (CV) were added to N and C. In general, when CVs in the data were less than 10%, reliable estimates of M were obtained. For normal and lognormal distributions, the estimates of M were more sensitive to the CVs in N than in C; when only C had error the estimates were close to the true. For Poisson and gamma distributions, opposite results were obtained. For instance, the estimates were more sensitive to the CVs in C than in N, with the largest REE from the scenario of error only in C. Two scenarios of high and low fishing mortality coefficient ( F) were generated, and the simulation results showed that the method performed better for the scenario with low F. This method was also applied to the published data for the anchovy ( Engraulis japonicus) of the Yellow Sea. Viable estimates of M were obtained for young groups, which may be explained by the fact that the great uncertainties in N and C observed for older Yellow Sea anchovy introduced large variation in the corresponding estimates of M.

  17. Application of Natural Isotopic Abundance ¹H-¹³C- and ¹H-¹⁵N-Correlated Two-Dimensional NMR for Evaluation of the Structure of Protein Therapeutics.

    Arbogast, Luke W; Brinson, Robert G; Marino, John P

    2016-01-01

    Methods for characterizing the higher-order structure of protein therapeutics are in great demand for establishing consistency in drug manufacturing, for detecting drug product variations resulting from modifications in the manufacturing process, and for comparing a biosimilar to an innovator reference product. In principle, solution NMR can provide a robust approach for characterization of the conformation(s) of protein therapeutics in formulation at atomic resolution. However, molecular weight limitations and the perceived need for stable isotope labeling have to date limited its practical applications in the biopharmaceutical industry. Advances in NMR magnet and console technologies, cryogenically cooled probes, and new rapid acquisition methodologies, particularly selective optimized flip-angle short transient pulse schemes and nonuniform sampling, have greatly ameliorated these limitations. Here, we describe experimental methods for the collection and analysis of 2D (1)H(N)-(15)N-amide- and (1)H-(13)C-methyl-correlated spectra applied to protein drug products at natural isotopic abundance, including representatives from the rapidly growing class of monoclonal antibody (mAb) therapeutics. Practical aspects of experimental setup and data acquisition for both standard and rapid acquisition NMR techniques are described. Furthermore, strategies for the statistical comparison of 2D (1)H(N)-(15)N-amide- and (1)H-(13)C-methyl-correlated spectra are detailed. PMID:26791974

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

    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)

  19. Study of protein metabolism and cell proliferation using 15N

    Investigations of nitrogen and protein metabolism with the stable isotope 15N were carried out in 11 patients with arteriosclerosis and 7 healthy controls. After oral application of 3 g 15NH4Cl (95 At% 15N) per 70 kg body weight the incorporation of the isotope 15N in plasma proteins and blood cells and the 15N elimination in urine were followed up. Retardations of 15N elimination, an accelerated incorporation of 15N in fibrin and a retarded 15N incorporation in platelet protein were observed in patients with arteriosclerosis. The described method enables complex assertions about protein metabolism of the whole body and so represents a possibility to evaluate objectively the influence of an intervention on metabolism. (author)

  20. Rapid mass spectrometric analysis of 15N-Leu incorporation fidelity during preparation of specifically labeled NMR samples

    Truhlar, Stephanie M E; Cervantes, Carla F; Torpey, Justin W;

    2008-01-01

    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......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...

  1. Species diversity and abundance of aphids and their natural enemies in a crop association

    Chevalier Mendes Lopes, Thomas; Hatt, Séverin; Starý, Petr; JAPOSHVILI, George; Francis, Frédéric

    2015-01-01

    Crop associations can be efficient to reduce aphid populations, by disrupting the visual and olfactory location of host plants. However, increasing the chemical and structural complexity of vegetation can also decrease the searching efficiency of predators and parasitoids, which are not always more abundant in complex habitats. Using attractive semiochemicals such as methyl salicylate (MeSA) combined with a crop association seems promising to maximise aphid control. We compared the abundances...

  2. 15N analysis in nutritional and metabolic research of infancy

    Investigation of protein metabolism in nutritional pediatric research by means of 15N tracer techniques has been relatively seldom used up to now. 15N-labelled compounds for these purposes are not injurious to health. The technique is based on oral or intravenous application of the tracer substances and on 15N analysis of the urine fractions. The subsequent calculation of protein synthesis and breakdown rate, turnover, and the reutilisation of amino acids from protein breakdown as well as the size of the metabolic pool offers detailed information of protein metabolism. Determination of these parameters were performed in infants on breast milk, formula feeding and on chemically defined diet. As an example of utilisation of D-amino acids for protein synthesis the 15N-D-phenylalanine retention of parenteral nutrition was found to be 33% of the applied dosis at an average. An oral 15N-glycine loading test proved to be of value for the prediction of the therapeutic effect of human growth hormone. 15N tracer technique was also tested in utilizing 15N-urea for bacterial protein synthesis of the intestinal flora and by incorporation of 15N from 15N-glycine and 15N-lysine into the jejunal mucosa for measuring the enterocyte regeneration. (author)

  3. Application of stable isotopes (δ{sup 34}S-SO{sub 4}, δ{sup 18}O-SO{sub 4,} δ{sup 15}N-NO{sub 3}, δ{sup 18}O-NO{sub 3}) to determine natural background and contamination sources in the Guadalhorce River Basin (southern Spain)

    Urresti-Estala, Begoña, E-mail: b.urresti@uma.es [Universidad de Málaga, Facultad de Ciencias, Grupo de Geodinámica Externa, Campus de Teatinos s/n, 29071 Málaga (Spain); Vadillo-Pérez, Iñaki; Jiménez-Gavilán, Pablo [Universidad de Málaga, Facultad de Ciencias, Grupo de Geodinámica Externa, Campus de Teatinos s/n, 29071 Málaga (Spain); Soler, Albert [Grup de Mineralogia Aplicada i Medi Ambient, Fac. Geologia, Universitat de Barcelona, Barcelona (Spain); Sánchez-García, Damián; Carrasco-Cantos, Francisco [Universidad de Málaga, Facultad de Ciencias, Grupo de Geodinámica Externa, Campus de Teatinos s/n, 29071 Málaga (Spain)

    2015-02-15

    The integrated use of isotopes (δ{sup 34}S-SO{sub 4}, δ{sup 18}O-SO{sub 4,} δ{sup 15}N-NO{sub 3}, δ{sup 18}O-NO{sub 3}), taking into account existing hydrogeological knowledge of the study area (mainly hydrochemical), was applied in the Guadalhorce River Basin (southern Spain) to characterise SO{sub 4}{sup 2−} and NO{sub 3}{sup −} sources, and to quantify natural background levels (NBLs) in groundwater bodies. According to Water Framework Directive 2000/60/EC and, more recently, Groundwater Directive 2006/118/EC, it is important to determine NBLs, as their correct assessment is the first, essential step to characterising groundwater bodies, establishing threshold values, assessing chemical status and identifying trends in pollutant concentrations. In many cases, NBLs are high for some parameters and types of groundwater, making it difficult to distinguish clearly between factors of natural or human origin. The main advantages of using stable isotopes in a complex area like the Guadalhorce River Basin that exhibits widely varying hydrogeological and hydrochemical conditions and longstanding anthropogenic influences (mainly agriculture, but also many others) is accurate determination of pollution sources and precise quantification of NBLs. Since chemical analyses only provides the concentration of pollutants in water and not the source, three isotopic sampling campaigns for sulphates (δ{sup 34}S-SO{sub 4}, δ{sup 18}O-SO{sub 4}) were carried out, in 2006, 2007 and 2012, and another one was conducted for nitrates (δ{sup 15}N-NO{sub 3}, δ{sup 18}O-NO{sub 3}), in 2009, in groundwater bodies in order to trace the origins of each pollutant. The present study identified different pollution sources of dissolved NO{sub 3}{sup −} in groundwater using an isotopic composition and quantified the percentage of natural (lithology, chemical and biological processes) and anthropogenic (fertilisers, manure and sewage) SO{sub 4}{sup 2−} and matched a concentration

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

    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. (author)

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

    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)

  6. Grafting and carbonated irrigation water in transport of 15N and in the tomato production

    The effects of CO2 application through irrigation water, and of grafting in transport of 15N and in the tomato production, were studied. These treatments were arranged in a 2 x 2 factorial scheme (with and without CO2 in irrigation water and grafted and non-grafted tomato), in a completely randomized design, with four replications. The injection of CO2 into the water began at 34 days after transplant of seedlings (DAT) and continued for all irrigations. The application of the sulfate of ammonium with abundance in atoms of 15N of 3.13% in plants destined to analysis was done at 45 DAT when the plants were in the middle of fructification. After 14 days of fertilizer (15N) application the plants were harvested, washed, dried and sent for analysis of 15N in plant tissue. The results demonstrated that CO2 and the grafting did not alter the transport of 15N in the plant. The production of commercial fruits was larger when CO2 was applied in water. (author)

  7. Marcação de fitomassa de cana-de-açúcar com aplicação de solução de uréia marcada com15N Sugarcane phytomass labeling with application of 15N-urea solution

    Carlos Eduardo Faroni

    2007-06-01

    Full Text Available O objetivo deste trabalho foi comparar três métodos de aplicação de solução de uréia marcada com15N (15N-uréia : pulverização foliar, injeção na base do colmo e imersão radicular, a fim de se definir qual seria o mais eficiente na marcação de fitomassa de cana-de-açúcar. O experimento foi instalado na Estação Experimental Apta - Pólo Regional Centro Sul, em Piracicaba, SP. A cana-de-açúcar, variedade SP80 3280, foi plantada em vasos preenchidos com aproximadamente 120 dm³ de Neossolo Quartzarênico de textura arenosa. O delineamento experimental foi inteiramente casualizado, com quatro repetições. A fitomassa de cana-de-açúcar dos três tratamentos, no 11º mês de desenvolvimento, não diferiu estatisticamente, e suas abundâncias de 15N foram superiores à natural, tendo-se verificado a seguinte ordem decrescente de marcação com 15N: parte aérea > rizoma > rizomas+raízes na camada de 0,0-0,2 m > raízes na camada de 0,2-0,4 m > raízes em profundidade maior que 0,4 m. Entre os métodos de aplicação de 15N-uréia, a injeção na base de colmos é o de mais fácil execução, o mais efetivo na marcação da fitomassa e o que apresentou a maior recuperação do traçador (96%. A aplicação foliar é comparável à injeção, somente na marcação e na recuperação do traçador no sistema radicular.The objective of this research was to compare three methods of 15N-urea solutions application: spray on leaf, injection in the plant base stem and root immersion, in order to define the most efficient labeling sugarcane phytomass with 15N method. The experiment was carried out at APTA - Pólo Regional Centro Sul, in Piracicaba, SP, Brazil, and the sugarcane variety SP80 3280 was planted in pots filled out with approximately 120 dm³ of a Typic Quartzipsamment soil. The experiment was conducted in a completely randomized design with four replicates. There were no difference between the methods in the plant parts dry

  8. Elemental abundances at early times: the nature of Damped Lyman-alpha systems

    Molla, Mercedes; Diaz, Angeles,; Ferrini, Federico

    1999-01-01

    The distribution of element abundances with redshift in Damped Ly-alpha (DLA) systems can be adequately reproduced by the same model reproducing the halo and disk components of the Milky Way Galaxy at different galactocentric distances: DLA systems are well represented by normal spiral galaxies in their early evolutionary stages.

  9. Assessment of the natural variation of low abundant metabolic proteins in soybean seeds using proteomics

    Using two-dimensional polyacrylamide gel electrophoresis and mass spectrometry, we investigated the distribution of the low abundant proteins that are involved in soybean seed development in four wild and twelve cultivated soybean genotypes. We found proteomic variation of these proteins within and...

  10. 15N-ammonium test in clinical research

    By use of the 15N-ammonium test the liver function is investigated under influence of hormonal contraceptives in women and in liver diseases in children. With the described noninvasive nonradioactive isotope test the ammonia detoxification capability and the urea synthesis capacity of the liver is determined by measuring of the 15N excretion in ammonia and urea in urine after oral administering of 15N-ammonium chloride. The 15N-ammonium test shows a significant influence of the hormonal contraceptives on the liver function and gives diagnostic evidence for liver diseases in children. (author)

  11. Studies with 15N-lysine in colostomized hens. 1

    0.2% L-lysine with an atom-% 15N excess (15N') of 48% were given per day through a throat probe to three colostomized laying hybrids in addition to a pelleted ration of 120 g per animal and day. In the following 4 days unlabelled L-lysine was given. As the labelled lysine was given three times a day, the development of 15N' excretion could be pursued. 80 minutes after the 15N'-lysine dose a distinct atom-% 15N' could be detected in urine. 6 hours after the 15N' application 2.9%, 4.2% and 2.7%, resp. of the applied 15N' amount in urine were found. 8 days after the beginning of the experiment the excretion of 15N' in urine was 17.5% on the average of the consumed 15N' amount. 44% of the nitrogen in the ration, however, was excreted in urine. The results show that the lysine N is excreted to a considerably lower extent in urine than the nitrogen in the remaining ration. (author)

  12. Model reconstruction of nitrate pollution of riverbank filtration using 15N and 18O data, Karany, Czech Republic

    Stable isotopes of O (δ18O) in water and N (δ15N) in NO3- have been used as natural indigenous groundwater tracers for sources of water and of NO3- at two riverbank filtration (RBF) water supply systems. Both RBF systems (Skorkov and Sojovice) have wells in unconsolidated Quaternary sediments close to the Jizera River (Czech Republic) that have been affected by increasing NO3- concentrations. The area is underlain by Turonian sandstones and marls that form a deeper bedrock aquifer. Sources of NO3- are local sewerage systems and landfills (point sources) and seasonal application of manure and inorganic fertilizers (diffuse sources). At RBF Skorkov recharge to wells can be modelled using a two-component model with 60% river water contribution and 40% of very shallow groundwater with an average residence time of one month. During periods of abundant precipitation, groundwater originates entirely from the unsaturated zone of the Quaternary aquifer; extensive pumping for over 40a has created new, bypassing flow paths that preferentially drain the contaminated unsaturated zone. During dry periods, wells are recharged by longer residence time groundwater from the Quaternary aquifer. At RBF Sojovice there is an additional recharge component of groundwater from the Turonian aquifer, which is sandier at this locality; this contains denitrified NO3- with highly positive δ15N values

  13. Abundance of non-native crabs in intertidal habitats of New England with natural and artificial structure

    Lovely, Christina M.; O’Connor, Nancy J.; Judge, Michael L.

    2015-01-01

    Marine habitats containing complex physical structure (e.g., crevices) can provide shelter from predation for benthic invertebrates. To examine effects of natural and artificial structure on the abundance of intertidal juvenile crabs, 2 experiments were conducted in Kingston Bay, Massachusetts, USA, from July to September, 2012. In the first experiment, structure was manipulated in a two-factor design that was placed in the high intertidal for 3 one-week periods to test for both substrate typ...

  14. Studies with 15N-lysine in colostomized hens. 6

    3 colostomized laying hybrides received 91.40 mg L-lysine-15N-excess (15N') each over a period of 4 days in a metabolism experiment with 15N-lysine. After another 4 days, during which the hens received the same rations supplemented by commercial L-lysine, the animals were butchered and divided into individual fractions. After hydrochloric hydrolysis of organs and tissues the heavy nitrogen of lysine, histidine and arginine were separated, quantitatively evaluated, processed and measured with an emission spectrometer. Atom-% 15N' on an average amounted to 0.20 in the liver, 0.16 in the kidneys, 0.06 in the flesh and 0.05 in the bones. Of the rediscovered 15N' applied, feces contained 8.1 %, urine 18.3 %, the eggs 24.3 %, the blood 4.9 %, the flesh 20.5 %, the bones 5.2 %, the gastrointestinal tract with its contents 4.5 %, the liver 3.5 %, the kidneys 0.9 %, the reproductive organs 3.7 %, and the rest 6.1 %. The quota of rediscovery of the 15N' applied was 95.7 %. 62 % of the total 15N' was rediscovered in eggs, body and feces as lysine 15N'. There was significantly more 15N' in all arginine fractions than in histidine. The quota of the lysine-15N' of the total 15N' differed considerably in the fractions: < 40 % bones and blood; 48-56 % gastrointestinal tract, feces, oviduct, kidneys; 62-63 % remaining ovary, rest; 69-71 % eggs, flesh, liver. It could be proved that the α-amino group of lysine is to a large extent incorporated into other amino acids. Further proof that the amino acid metabolism proceeds in two phases was submitted, i.e. higher amounts of amino acids previously deposited in the body are used for egg synthesis. (author)

  15. Nature's Starships. I. Observed Abundances and Relative Frequencies of Amino Acids in Meteorites

    Cobb, Alyssa K

    2014-01-01

    The class of meteorites called carbonaceous chondrites are examples of material from the solar system which have been relatively unchanged from the time of their initial formation. These meteorites have been classified according to the temperatures and physical conditions of their parent planetesimals. We collate available data on amino acid abundance in these meteorites and plot the concentrations of different amino acids for each meteorite within various meteorite subclasses. We plot average concentrations for various amino acids across meteorites separated by subclass and petrologic type. We see a predominance in the abundance and variety of amino acids in CM2 and CR2 meteorites. The range in temperature corresponding to these subclasses indicates high degrees of aqueous alteration, suggesting aqueous synthesis of amino acids. Within the CM2 and CR2 subclasses, we identify trends in relative frequencies of amino acids to investigate how common amino acids are as a function of their chemical complexity. The...

  16. Unveiling the Nature of the "Green Pea" Galaxies: Oxygen and Nitrogen Chemical Abundances

    Amorín, R. O.; Pérez-Montero, E.; Vílchez, J. M.

    2011-07-01

    We present recent results on the oxygen and nitrogen chemical abundances in the extremely compact, low-mass starburst galaxies at redshifts 0.1-0.3 usually referred to as "green pea" galaxies. We show that they are metal-poor galaxies (~1/5 solar) with lower oxygen abundances than star-forming galaxies of similar mass and N/O ratios unusually high for galaxies of the same metallicity. Recent, rapid, and massive inflows of cold gas, possibly coupled with enriched outflows from supernova winds, are used to explain the results. This is consistent with the known "pea" galaxy properties and suggest that these rare objects are experiencing a short and extreme phase in their evolution.

  17. Nature's starships. I. Observed abundances and relative frequencies of amino acids in meteorites

    Cobb, Alyssa K.; Pudritz, Ralph E., E-mail: cobbak@mcmaster.ca, E-mail: pudritz@physics.mcmaster.ca [Origins Institute, McMaster University, ABB 241, 1280 Main Street, Hamilton, ON L8S 4M1 (Canada)

    2014-03-10

    The class of meteorites called carbonaceous chondrites are examples of material from the solar system which have been relatively unchanged from the time of their initial formation. These meteorites have been classified according to the temperatures and physical conditions of their parent planetesimals. We collate available data on amino acid abundance in these meteorites and plot the concentrations of different amino acids for each meteorite within various meteorite subclasses. We plot average concentrations for various amino acids across meteorites separated by subclass and petrologic type. We see a predominance in the abundance and variety of amino acids in CM2 and CR2 meteorites. The range in temperature corresponding to these subclasses indicates high degrees of aqueous alteration, suggesting aqueous synthesis of amino acids. Within the CM2 and CR2 subclasses, we identify trends in relative frequencies of amino acids to investigate how common amino acids are as a function of their chemical complexity. These two trends (total abundance and relative frequencies) can be used to constrain formation parameters of amino acids within planetesimals. Our organization of the data supports an onion shell model for the temperature structure of planetesimals. The least altered meteorites (type 3) and their amino acids originated near cooler surface regions. The most active amino acid synthesis likely took place at intermediate depths (type 2). The most altered materials (type 1) originated furthest toward parent body cores. This region is likely too hot to either favor amino acid synthesis or for amino acids to be retained after synthesis.

  18. Using natural isotopic abundances to determine the source of nitrous oxide (N2O) emissions

    Mothet, A.; Sebilo, M.; Laverman, A. M.; Vaury, V.; Mariotti, A.

    2012-04-01

    Numerous greenhouse gas studies have focused on carbon dioxide (CO2), whereas nitrous oxide (N2O) also plays a major role in global warming. Indeed, while nitrous oxide is 1000 times less concentrated than CO2 in the atmosphere, it is 300 times more efficient in terms of global warming potential. In addition, its atmospheric concentration increases with 0,3 % per year. According to the literature, nitrous oxide is produced, in soils and sediments, by two major processes: (1) Nitrification, mediated by autotrophic nitrifying bacteria under oxic conditions; (2) Denitrification, mediated by heterotrophic denitrifying bacteria under anoxic conditions. Denitrification induces intensive, localized and instantaneous fluxes. N2O emissions can be easily measured and modeled. In contrast, nitrification induces weak emissions, but spatially and temporally extended. Therefore, this process could represent a large potential of N2O emissions from soils and sediments. The study of isotopomer's isotopic composition of N2O, i.e. the intramolecular distribution or site preference (SP) determined by 15N measurement allows the determination of the origin of N2O emissions (nitrification vs. denitrification). Recent studies on pure cultures have showed that SP associated with nitrification is 35 ‰ while SP associated with denitrification is 0 ‰. The aim of this study was to determine SP associated with denitrification in soils and sediments, taking into account the environmental denitrifying bacterial communities, and under different environmental variables. To this end, flow-through reactors were used to determine denitrification rates at different temperatures and varying substrate (nitrate) concentrations. Site preference was measured for the different experiments. Different experiments of denitrification were realized in sediment flow through reactors under denitrifying conditions (anoxia, presence of organic matter and nitrate). We used acetylene (25°C) to block the enzyme

  19. Species richness and abundance of hesperioidea and papilionoidea (lepidoptera) in Las Delicias natural reserve, Santa Marta, Magdalena, Colombia

    In the foothills of the Sierra Nevada de Santa Marta, Colombia, are formations of dry tropical secondary forest hosting a fauna representative of lepidoptera, which can be used as an indicator of group condition, because of their sensitivity to intervention and specificity in the use of resources; in the present study the changes in richness and abundance of butterflies hesperioidea papilionoidea in nature reserve Las Delicias were evaluated. Two sampling sites with different degrees of intervention were selected. The first site is located between 400- 550 over sea level, while the second at 200 m. We performed four samples, from April to July 2008; using two networks lepidopterist and 10 van someren rydon traps baited with macerated fruit and fish. We captured 432 individuals belonging to 66 species, distributed in 52 genera. Nymphalidae were the most rich family (42) and abundance (250); highlighting the species mechanitis lysimnia fabricius (41 specimens), typical in forest with very good coverage. Site 2, was the most diverse (48) and abundance (236), because in this place there was a greater stratification and tree coverage, and the presence of water resources during the sampling. With the arrival of rain in June and July, there was greater flowering and fruiting of vegetation in the area, increasing the availability of resources and therefore a greater richness and abundance of papilionoidea and hesperioidea in the study area.

  20. Multinuclear NMR of 15 N labelled organic molecules

    The paper presents the application of multinuclear NMR techniques to the study of 15 N labeled organic molecules. There are some important points of great interest in such type of research, namely, structure determination, i.e. location of the 15 N in molecule and determination of 15 N concentration in order to obtain quantitative results about the intramolecular short and long range interaction. Different NMR techniques were used in the study of 13 C, 1 H and 15 N. Obtaining the 15 N NMR signal imposes some special preparation of the spectrometer. First, we had to manage a very large spectral window (-400 to +1200 ppm) which makes difficult finding the signal. Secondly, in the condition of proton decoupling, in a very large band, a decrease of the signal can occur due to the NOE negative effect. To avoid this effect, other decoupling method, called 'inverse gated 1 H decoupling' was used. As a reference, for 15 N, we used CH3NO2, fixed at 0 ppm. In order to find the suitable spectral window we used the formamide (15 N). The results of obtaining the 15 N-labeled procaine are presented. (author)

  1. Does human activity impact the natural antibiotic resistance background? Abundance of antibiotic resistance genes in 21 Swiss lakes.

    Czekalski, Nadine; Sigdel, Radhika; Birtel, Julia; Matthews, Blake; Bürgmann, Helmut

    2015-08-01

    Antibiotic resistance genes (ARGs) are emerging environmental contaminants, known to be continuously discharged into the aquatic environment via human and animal waste. Freshwater aquatic environments represent potential reservoirs for ARG and potentially allow sewage-derived ARG to persist and spread in the environment. This may create increased opportunities for an eventual contact with, and gene transfer to, human and animal pathogens via the food chain or drinking water. However, assessment of this risk requires a better understanding of the level and variability of the natural resistance background and the extent of the human impact. We have analyzed water samples from 21 Swiss lakes, taken at sampling points that were not under the direct influence of local contamination sources and analyzed the relative abundance of ARG using quantitative real-time PCR. Copy numbers of genes mediating resistance to three different broad-spectrum antibiotic classes (sulfonamides: sul1, sul2, tetracyclines: tet(B), tet(M), tet(W) and fluoroquinolones: qnrA) were normalized to copy numbers of bacterial 16S rRNA genes. We used multiple linear regression to assess if ARG abundance is related to human activities in the catchment, microbial community composition and the eutrophication status of the lakes. Sul genes were detected in all sampled lakes, whereas only four lakes contained quantifiable numbers of tet genes, and qnrA remained below detection in all lakes. Our data indicate higher abundance of sul1 in lakes with increasing number and capacity of wastewater treatment plants (WWTPs) in the catchment. sul2 abundance was rather related to long water residence times and eutrophication status. Our study demonstrates the potential of freshwater lakes to preserve antibiotic resistance genes, and provides a reference for ARG abundance from lake systems with low human impact as a baseline for assessing ARG contamination in lake water. PMID:25913323

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

    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 15N and 13C Isotopic Signatures of Hay and Soil Samples Differ?

    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 δ15N and δ13C isotopic composition of soil and hay samples of 21 organic and 34 conventional grasslands in two German regions. We also used Δδ15N15N plant - δ15N 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 δ13C in hay and δ15N in both soil and hay between management types, but showed that δ13C abundances were significantly lower in soil of organic compared to conventional grasslands. Δδ15N values implied that management types did not substantially differ in nitrogen cycling. Only δ13C 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 used in practice

  4. ASSESSING ABUNDANCE DISTRIBUTIONS IN NATURAL COMMUNITIES OF ECTOMYCORRHIZAS ALONG AN ENVIRONMENTAL GRADIENT

    Alpha diversity indices often fail to distinguish between natural populations that a more detailed investigation of the distribution of ramets among types would show are quite different. We studied the effectiveness of applying SHE analyses to morphotype classifications of ectom...

  5. EVALUACIÓN DEL MÉTODO DE LA ABUNDANCIA NATURAL 15N EN LA ESTIMACIÓN DEL EFECTO DE LA TRANSFERENCIA DE NITRÓGENO DE LA LEGUMINOSA Canavalia ensiformis (CANAVALIA SOBRE LA NUTRICIÓN NITROGENADA DE LA PLANTA ASOCIADA Musa acuminata (PLÁTANO

    Natacha Motisi

    2007-01-01

    Full Text Available La asociación de una leguminosa con un cultivo de cosecha ha demostrado ser una práctica eficaz para aportar nitrógeno (N al sistema suelo-planta y así reducir el uso de fertilizantes. El objetivo de este estudio fue analizar la utilidad del método de la abundancia natural 15N para evaluar ese aporte. Se realizó un ensayo en macetas bajo condiciones de invernadero con la asociación canavalia-plátano, con el objeto de estimar la contribución de los exudados de la leguminosa y del N producto de la descomposición de sus raíces después del corte de la parte aérea. Las estimaciones fueron realizadas con un modelo de compartimientos que tiene en cuenta la discriminación isotópica en el suelo y en el plátano. Del N total absorbido por el plátano, 5 % provino de los exudados de canavalia, 53 % del N liberado por la descomposición de las raíces y 42 % del N del suelo. La contribución de los exudados fue relativamente baja a causa de una fuerte competición entre canavalia y plátano, principalmente por el fósforo disponible en el suelo. El contenido de 15N de la última media hoja adulta del plátano mostró una alta correlación con el de la planta entera. Esto sugiere que la última hoja podría ser utilizada como indicador de la transferencia de N desde la leguminosa. La determinación de la transferencia de N durante el ciclo de crecimiento de canavalia, así como la evaluación del indicador, necesitan una calibración en condiciones de campo, la cual debería ser desarrollada para cada tipo de suelo.

  6. Preparation of 15N labelled protein sample by gene engineering technology

    Using the advanced multi-dimension heteronuclear pulses and isotope labelled protein technique, nuclear magnetic resonance spectroscopy has become an important tool in analysis of the solution conformation of protein. On the basis of the high level expression of a protein-trichosanthin in recombinant E.coli using DNA, 15N was used to label the protein, the 15N labelled trichosanthin was obtained by affinity chromatography on Ni-NTA agarose. Terminating pregnant effect in mice showed that this recombinant protein had the same activity as natural trichosanthin. A 1H-15N heteronuclear single-quantum coherence (HSQC) spectrum was obtained from an AM-500 NMR spectrometer, demonstrating that this method is suitable in preparing labelled protein sample for NMR

  7. Application of 15N in biochemistry, agriculture and medicine

    The compendium on application of 15N in the biosciences comprises 7 chapters. The 1st chapter comprehends introductory remarks on isotopes in general and on nitrogen isotopes in particular. In the 2nd chapter fundamentals of 15N tracer techniques are discussed. The 3rd chapter deals with experiment programs and the evaluation of experiments. The methodology of sample preparation as well as of isotope analysis is treated in chapter 4. The chapters 5 to 7 deal with the application of 15N as tracer in biochemistry, agricultural research and medicine, resp. Relevant literature is added to each chapter

  8. NMR spectroscopic studies of 15N labelled geminally disubstituted cyclotriphosphazenes

    It is demonstrated by means of some selected 15N labelled geminally disubstituted cyclotriphosphazenes, 15N3P3X4Y2 (X = Cl; Y = F, NH2, or SEt), as an example, that the coupling constants 1Jsub(PN) may be of different signs. The absolute value of 1Jsub(PN) is significantly influenced only by those substituents, which are bonded to the phosphorus nucleus directly concerned in the coupling. Also the 15N chemical shifts are only changed by substituents on directly bonded phosphorus atoms. (author)

  9. Paramagnetic relaxation enhancement solid-state NMR studies of heterogeneous catalytic reaction over HY zeolite using natural abundance reactant.

    Zhou, Lei; Li, Shenhui; Su, Yongchao; Li, Bojie; Deng, Feng

    2015-01-01

    Paramagnetic relaxation enhancement solid-state NMR (PRE ssNMR) technique was used to investigate catalytic reaction over zeolite HY. After introducing paramagnetic Cu(II) ions into the zeolite, the enhancement of longitudinal relaxation rates of nearby nuclei, i.e.(29)Si of the framework and (13)C of the absorbents, was measured. It was demonstrated that the PRE ssNMR technique facilitated the fast acquisition of NMR signals to monitor the heterogeneous catalytic reaction (such as acetone to hydrocarbon) using natural abundance reactants. PMID:25616847

  10. Species composition and relative seasonal abundance of spiders from the field and tree layers of the Roodeplaat Dam Nature Reserve

    Anna S. Dippenaar-Schoeman

    1989-10-01

    Full Text Available A survey of spiders was carried out at the Roodeplaat Dam Nature Reserve near Pretoria. Over a 4-year period 10 270 spiders were collected from grasses, herbs and trees. A total of 82 genera of spiders representing 27 families were recorded. Of all the spiders caught, 29,3 percent belonged to the Tetrag-nathidae, 22,7 percent to the Araneidae and 21,4 percent to the Salticidae. The proportion of spiders in each of the remaining 24 families did not exceed 6 percent of the total catch. The species composition and seasonal abundance are discussed.

  11. Relationship between the abundance of aphids and their natural enemies in cereal fields and landscape composition

    Hassan, D. A.; Parisey, N.; Burel, F.; Plantegenest, M.; Kindlmann, Pavel; Butet, A.

    2012-01-01

    Roč. 2, č. 2 (2012), s. 89-101. ISSN 1805-0174 R&D Projects: GA MŠk(CZ) ED1.1.00/02.0073 Institutional support: RVO:67179843 Keywords : agroecosystems * landscape structure * crop pests * aphids * biological control * semi-natural habitats Subject RIV: EH - Ecology, Behaviour

  12. The absorption, utilization and distribution of nitrate 15N and ammonium 15N in Populus Tomentosa seedlings

    Effects of different nitrogen sources (NO3-, NH4+) on the absorption, distribution and utilization of nitrogen on Populus tenement's seedlings (clone 50) was studied by using the 15N trace technique. Results showed that the Populus tenement's seedlings had the same nitrogen take up pattern: tissue nitrogen content grew up after fertilization, remarkbaly rising up after one week and reached peak after 28 days. Although the treatments are different, the tissue N content was about the same between 0.6g · plant-1. The maximum absorption of NO3-15N and NH4-15N was 0.26g · plant-1 and 0.12g · plant -1, which accounted for 39.15% and 19.95% of total nitrogen, respectively. The nitrogen use efficiency (NUE) of two nitrogen sources varied gignificantly. The maximum NUE of NO3-15N reached 25.83%, nearly twice of that of NH4-15N (12.03%). Hence we conclude that Populus tomentosa seedlings (clone 50) prefer to absorb NO3-. Nitrogen distribution rate changed obviously among different organs and the trend was leaf>root>stem. In the leaf, the distribution of NO3-15N was higher than that of NH4-15N. (authors)

  13. Studies with 15N-Lysine in colostomized hens. 4

    Each of 3 colostomized laying hens received per os 0.2% L-lysine with 48 atom-% 15N excess (15N') labelled in α-position in addition to a pelleted laying hen ration of 120 g over a period of 4 days. On the following 4 days they received equal amounts of unlabelled lysine. The eggs laid during the 8 days of the experiment were separated into the egg white, the yolk and the eggshell, and the total and heavy nitrogen in the individual fractions were determined. Above that, 17 amino acids and their atom-%15N' were determined in the 19 samples of the white and yolk of egg. Of the total 15N' from the lysine fed in the 4 days, 10.1% were found in the yolk, 10.5% in the egg white and 1.1% in the eggshells of the eggs laid during the 8 days of the experiment. 85% of the total amino acid 15N' of the yolk and 86% of the egg white detected to be lysine 15N'. The 15N' amount of the other 16 amino acids was mainly concentrated in the two acid and basic amino acids. Approximately 50% of the non-lysine 15N' in the egg are contained in aspartic acid, glutamic acid, histidine and arginine. A very low incorporation of the labelled lysine only could be detected in the aromatic and sulphur-containing amino acids from both the yolk and the egg white 43% of the 15N' was detected in the 10 essential and semi-essential (except lysine) and 57% in the 6 non-essential amino acids of the yolk and 52% and 48% resp. of the egg white. One can summarise that the incorporation of 15N' into the egg shows the same development as that of the labelled amino acids of the wheat protein and that 15% of the lysine 15N' could be detected in the 16 other amino acids. (author)

  14. A New Method for Estimating Bacterial Abundances in Natural Samples using Sublimation

    Glavin, Daniel P.; Cleaves, H. James; Schubert, Michael; Aubrey, Andrew; Bada, Jeffrey L.

    2004-01-01

    We have developed a new method based on the sublimation of adenine from Escherichia coli to estimate bacterial cell counts in natural samples. To demonstrate this technique, several types of natural samples including beach sand, seawater, deep-sea sediment, and two soil samples from the Atacama Desert were heated to a temperature of 500 C for several seconds under reduced pressure. The sublimate was collected on a cold finger and the amount of adenine released from the samples then determined by high performance liquid chromatography (HPLC) with UV absorbance detection. Based on the total amount of adenine recovered from DNA and RNA in these samples, we estimated bacterial cell counts ranging from approx. l0(exp 5) to l0(exp 9) E. coli cell equivalents per gram. For most of these samples, the sublimation based cell counts were in agreement with total bacterial counts obtained by traditional DAPI staining. The simplicity and robustness of the sublimation technique compared to the DAPI staining method makes this approach particularly attractive for use by spacecraft instrumentation. NASA is currently planning to send a lander to Mars in 2009 in order to assess whether or not organic compounds, especially those that might be associated with life, are present in Martian surface samples. Based on our analyses of the Atacama Desert soil samples, several million bacterial cells per gam of Martian soil should be detectable using this sublimation technique.

  15. Origin and tracing techniques of high 15N nitrogen compounds in industrial environments

    Effluents and process waters from various industrial plants were investigated for the 15N/14N isotope ratio in nitrate and ammonia. It was found that large isotope fractionation occurs in cases where ammonia is involved in gas-liquid phase changes. This feature was found to occur in two coke oven plants where ammonia gas is removed from a gas stream by solution in water, in an ammonia sulphate plant where ammonia gas is absorbed in sulphuric acid and in a water treatment plant where ammonia is removed from (high pH) water by blowing air through the process water. In all these cases 15N isotope enrichments (in the range of 10 to 30 per mille) occurred. These enrichments are in excess of those found naturally. Ammonia in such wastewaters essentially retains this high 15N content when it is converted to nitrate underground: which occurs rapidly under well-oxidised conditions. Nitrate is a fairly conservative tracer and its contamination in water can be followed readily. In the low recharge environment in the central parts of South Africa evidence of waste management practices of 10-20 years earlier were still quite evident using this isotopic label. The high 15N nitrate signal could be used to distinguish industrial nitrogen pollution from pollution by local sewage disposal systems. Vegetation that derives its nitrogen from such high 15N sources retains the isotope signature of its source. Grass and other annual plants then exhibit the isotope signature of the water of a specific year. Trees exhibit the isotope signature of deeper water, which shows the effects of longer term pollution events. The use of high 15N as tracer enables the source apportionment of nitrogen derived pollution in these specific circumstances. (author)

  16. Fertilizer 15N balance in a coffee cropping system: a case study in Brazil

    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 15N 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 15N 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 15N 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 15N, and plants outside sub-plots were used to evaluate dry matter. Volatilization losses of NH3 were estimated using special collectors. Leaching of fertilizer-N was estimated from deep drainage water fluxes and 15N concentrations of the soil solution at 1 m soil depth. At the end of the 2-year evaluation, the recovery of 15N 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 very small (2.0 % and 0.9 %, respectively

  17. 15N/14N variations in Cretaceous Atlantic sedimentary sequences: implication for past changes in marine nitrogen biogeochemistry

    Rau, G.H.; Arthur, M.A.; Dean, W.E.

    1987-01-01

    At two locations in the Atlantic Ocean (DSDP Sites 367 and 530) early to middle Cretaceous organic-carbon-rich beds ("black shales") were found to have significantly lower ??15N values (lower 15N/14N ratios) than adjacent organic-carbon-poor beds (white limestones or green claystones). While these lithologies are of marine origin, the black strata in particular have ??15N values that are significantly lower than those previously found in the marine sediment record and most contemporary marine nitrogen pools. In contrast, black, organic-carbon-rich beds at a third site (DSDP Site 603) contain predominantly terrestrial organic matter and have C- and N-isotopic compositions similar to organic matter of modern terrestrial origin. The recurring 15N depletion in the marine-derived Cretaceous sequences prove that the nitrogen they contain is the end result of an episodic and atypical biogeochemistry. Existing isotopic and other data indicate that the low 15N relative abundance is the consequence of pelagic rather than post-depositional processes. Reduced ocean circulation, increased denitrification, and, hence, reduced euphotic zone nitrate availability may have led to Cretaceous phytoplankton assemblages that were periodically dominated by N2-fixing blue-green algae, a possible source of this sediment 15N-depletion. Lack of parallel isotopic shifts in Cretaceous terrestrially-derived nitrogen (Site 603) argues that the above change in nitrogen cycling during this period did not extend beyond the marine environment. ?? 1987.

  18. Rate of [15N] leucine incorporation and determination of nitrogenous fractions from gastro-jejunal secretion in fasting humans

    The aim of this study was to quantify the nitrogen fraction flow rates in gastro-jejunal secretions in fasting humans and to determine the [15N] leucine incorporation into the secreted proteins. A double lumen intestinal perfusion method was used in 5 healthy volunteers. Plasma and gastro-jejunal juices were collected during a 15-h intravenous [15N] leucine infusion. Total, soluble and insoluble nitrogen, amino acids and [15N] leucine enrichment were measured. The total nitrogen flow rate was 7.2 ± 1.9 mmol.h-1 and 58% was ethanol soluble. The amino-acid composition remained constant and glycine was the most abundant. The plasma [15N] leucine enrichment at the isotopic plateau was 4.8 ± 0.9 mol% excess. The [15N] leucine enrichment in the intestinal chyme increased asymptotically to reach a plateau after 5h. The [15N] leucine enrichment at the plateau and the fractional synthesis rate of secreted proteins were 1.6 ±0.5 mol% excess and 21.5 ± 3.3% h-1, respectively. These results show that the composition of the basal gastro-jejunal secretion is very stable. A part of this secretion is composed of proteins with rapid synthesis rates. (authors). 33 refs., 4 figs., 2 tabs

  19. Rapid mass spectrometric analysis of 15N-Leu incorporation fidelity during preparation of specifically labeled NMR samples

    Truhlar, Stephanie M.E.; Cervantes, Carla F.; Torpey, Justin W.; Kjaergaard, Magnus; Komives, Elizabeth A.

    2008-01-01

    Advances in NMR spectroscopy have enabled the study of larger proteins that typically have significant overlap in their spectra. Specific 15N-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 15N-amino acid incorporation. The selectively labeled protein is proteolyzed, and the resulting peptides are analyzed using MALDI mass spectrometry. The 15N 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 15N-amino acid prevents the scrambling of the 15N label that is observed when equimolar amounts are used. MALDI TOF-TOF MS/MS data provide additional information that shows where the “extra” 15N labels are incorporated, which can be useful in confirming ambiguous assignments. The described procedure provides a rapid technique to monitor the fidelity of selective labeling that does not require a lot of protein. These advantages make it an ideal way of determining optimal expression conditions for selectively labeled NMR samples. PMID:18567787

  20. Balance study of the fate of 15N fertilizer

    An interim report is presented on a series of experiments with wooden box-type lysimeters (60 cm x 60 cm x 70 cm) loaded with a sandy soil, a loess soil and straw-amended soil. The lysimeters support crops rotated over a five-year period to be studied - potato, barley, sugar-beet, barley (with winter rape) and finally (1979) potato. Each lysimeter received split applications of urea at total rates of 0, 50 or 100 kg.ha-1. The effects of soil residues of the herbicide monolinuron were also studied. The report deals with data collected during the first three years of the planned experiments (1975 - 1977 inclusive). 15N-labelled urea (47 atom 15N% excess) was initially used but in some experiments this was followed by applications of unlabelled urea in order to study the fate of the residual 15N in the subsequent years. The results to date indicated that in the first year highest recoveries in the plant of the applied 15N obtained on the sandy soil. The low recoveries of 15N in the subsequent years when unlabelled urea was supplied also indicated significant storage by soil or root organic matter of the applied 15N. Compared with the control (zero application of urea nitrogen), potato took up more total nitrogen in the presence of fertilizer including more of the unlabelled soil pool nitrogen. Analyses of the soil profiles in terms of total soil nitrogen and fertilizer-derived nitrogen (on the basis of 15N assays) indicated leaching of the labelled nitrogen down the soil profile in all cases during the three-year period. Analysis of NO3-N in leachates confirmed the presence of labelled urea-derived nitrogen. (author)

  1. Peptides and proteins in a confined environment: NMR spectra at natural isotopic abundance.

    Pastore, Annalisa; Salvadori, Severo; Temussi, Piero Andrea

    2007-05-01

    Confinement of proteins and peptides in a small inert space mimics the natural environment of the cell, allowing structural studies in conditions that stabilize folded conformations. We have previously shown that confinement in polyacrylamide gels (PAGs) is sufficient to induce a change in the viscosity of the aqueous solution without changing the composition and temperature of the solvent. The main limitation of a PAG to run NMR experiments in a confined environment is the need for labelling the peptides. Here we report the use of the agarose gel to run the NMR spectra of proteins and peptides. We show that agarose gels are completely transparent in NMR experiments, relieving the need for labelling. Although it is necessary to expose biomolecules to fairly high temperatures during sample preparation, we believe that this is not generally an obstacle to the study of peptides, and found that the method is also compatible with temperature-resistant proteins. The mesh of agarose gels is too wide for direct effects of confinement on the stability of proteins but confinement can be easily exploited to interact the proteins with other reagents, including crowding macromolecules that can eventually lead to fold stabilization. The use of these gels is ideally suited for low-temperature studies; we show that a very flexible peptide at subzero temperatures is stabilized into a well-folded conformation. PMID:17436341

  2. Utilization of 15N-urea in laying hens. 3

    In 3 colostomized laying hens the incorporation of heavy nitrogen from urea into the amino acids of the 21 eggs laid during the 8-day experiment was determined. In these eggs the content of 15 amino acids was ascertained separately in white and yolk of the eggs and their atom-% 15N excess (15N') was determined. The heavy nitrogen could be detected in all amino acids investigated. The incorporation of 15N' into the essential amino acids of the white and yolk of eggs is very low. Of the 15N' amount of the urea applied 0.18% could be detected in the 9 essential amino acids of the white of egg and 0.12% in those of the yolk. For the 6 analyzed nonessential amino acids the rediscovery quota of 15N' in the white of egg was 0.50% and in the yolk 0.81% is that the NPN-source urea is insignificant for egg protein synthesis. (author)

  3. Impact of increasing the enrichment of 15N in reduced-activation ferritic steels on 14C production of tokamak reactors

    The impact of increasing the enrichment of 15N in F82H of a fusion reactor has been investigated in order to increase the fraction of shallow land burial. In Japan, the radioactive waste having any single radionuclide, exceeding the limit concentration value determined by the Nuclear Safety Commission, will not qualify as a low level waste (LLW), which can be disposed by shallow land burial. The regulation of carbon-14, which has a half life of 5730 years, was 37 kBq/g. Low activation ferritic steel is the most promising structural materials under research for fusion because of its good irradiation properties at high temperature and low activation. From the viewpoint of toughness and reliability, it is preferable to mix more than 200 ppm nitrogen in F82H. In DT fusion neutron environment, 14C is produced by 14N(n,p)14C nuclear reaction. The natural abundance of nitrogen isotopes is 99.63% of 14N and 0.37% of 15N. Then increasing 15N enrichment is effective to reduce the production of 14C. SlimCS, which is a compact demonstration reactor characterized by low aspect ratio (A) and reduced-size center solenoid (CS), has been designed in JAEA. The reactor has a major radius of 5.5 m and aspect ratio of 2.6. It produces a fusion output of 2.95 GW, which corresponds to a neutron wall loading of 3.6 MW/m2. A tritium breeding blanket in outboard side consists of both 30 cm thick replaceable blanket and 50 cm thick permanent blanket. In the inboard side, it has only replaceable blanket of 30 cm thickness to realize low-A. Neutron transport calculations have been performed using ANISN with nuclear cross sections from the FUSION-40 based on JENDL 3.1. The concentration of nitrogen in F82H is 200 ppm. The enrichment of 15N was varied from natural abundance of 0.37% to 95%. After thirty years operation with the operating rate of 50%, the 14C concentrations in F82H of the surface of outboard permanent blanket decreased from 78 kBq/g to 10 kBq/g by increasing the enrichment of 15N

  4. Determining the isotopic abundance of a labeled compound by mass spectrometry and how correcting for natural abundance distribution using analogous data from the unlabeled compound leads to a systematic error.

    Schenk, David J; Lockley, William J S; Elmore, Charles S; Hesk, Dave; Roberts, Drew

    2016-04-01

    When the isotopic abundance or specific activity of a labeled compound is determined by mass spectrometry (MS), it is necessary to correct the raw MS data to eliminate ion intensity contributions, which arise from the presence of heavy isotopes at natural abundance (e.g., a typical carbon compound contains ~1.1% (13) C per carbon atom). The most common approach is to employ a correction in which the mass-to-charge distribution of the corresponding unlabeled compound is used to subtract the natural abundance contributions from the raw mass-to-charge distribution pattern of the labeled compound. Following this correction, the residual intensities should be due to the presence of the newly introduced labeled atoms only. However, this will only be the case when the natural abundance mass isotopomer distribution of the unlabeled compound is the same as that of the labeled species. Although this may be a good approximation, it cannot be accurate in all cases. The implications of this approximation for the determination of isotopic abundance and specific activity have been examined in practice. Isotopically mixed stable-atom labeled valine batches were produced, and both these and [(14) C6 ]carbamazepine were analyzed by MS to determine the extent of the error introduced by the approach. Our studies revealed that significant errors are possible for small highly-labeled compounds, such as valine, under some circumstances. In the case with [(14) C6 ]carbamazepine, the errors introduced were minor but could be significant for (14) C-labeled compounds with particular isotopic distributions. This source of systematic error can be minimized, although not eliminated, by the selection of an appropriate isotopic correction pattern or by the use of a program that varies the natural abundance distribution throughout the correction. PMID:26916110

  5. A thalium-doped sodium iodide well counter for radioactive tracer applications with naturally-abundant 40K

    The use of a thallium-doped sodium-iodide well-type scintillation detector for the assay of the low-activity radioisotope 40K, in open-source potassium chloride aqueous solutions, is described. The hazards, safety concerns and radiowaste generation associated with using open-source radioactive isotopes can present significant difficulties, the use of hot cells and escalated costs in radioanalytical laboratory research. A solution to this is the use of low-hazard alternatives that mimic the migration and dispersion characteristics of notable fission products (in this case 137Cs). The use of NaI(Tl) as a detection medium for naturally-abundant levels of 40K in a range of media is widespread, but the use of 40K as a radioactive tracer has not been reported. The use of such low-activity sources is often complicated by the ability to detect them efficiently. In this paper a scintillator detector designed to detect the naturally-abundant 40K present in potassium chloride in tracer applications is described. Examples of the use of potassium chloride as a tracer are given in the context of ion exchange and electrochemical migration studies, and comparisons in performance are drawn from literature with hyper pure germanium semiconductor detectors, which are more commonly utilised detectors in high-resolution counting applications. -- Highlights: • Large crystal NaI(Tl) well counter used to detect an introduced potassium tracer. • Detector displays comparable low-activity counting characteristics as some HPGEs. • Nonactive Cs+ ion exchange radiometrically monitored through K+ displacement. • Electrokinetic decontamination of potassium from concrete observed radiologically. • Combined use of detector and 40K tracer can eliminate experimental radioactive risk

  6. 15N-labelled pyrazines of triterpenic acids

    Triterpenoid pyrazines from our research group were found selectively cytotoxic on several cancer cell lines with IC50 in low micromolar range. This sparked our interest in preparing their labeled analogs for metabolic studies. In this work, we prepared a set of non-labeled pyrazines from seven triterpenoid skeletal types along with their 15N labelled analogs. In this work, we present the synthesis and characterization of the target 15N labelled pyrazines. Currently, these compounds are being studied in complex metabolic studies. (author)

  7. The 15N ground state studied with elastic electron scattering

    The C0 elastic electron scattering form factor of 15N has been measured over a momentum transfer range q = 0.4-3.2 fm-1. From these form factor data the ground state charge density and its RMS radius (2.612±0.009 fm) were determined. This charge density as well as its difference with that of 16O were compared to recent large-basis shell-model calculations. Although these calculations describe the individual charge density reasonably, the difference between 16O and 15N cannot be reproduced satisfactorily. (orig.)

  8. Biosynthetic uniform 13C,15N-labelling of zervamicin IIB. Complete 13C and 15N NMR assignment.

    Ovchinnikova, Tatyana V; Shenkarev, Zakhar O; Yakimenko, Zoya A; Svishcheva, Natalia V; Tagaev, Andrey A; Skladnev, Dmitry A; Arseniev, Alexander S

    2003-01-01

    Zervamicin IIB is a member of the alpha-aminoisobutyric acid containing peptaibol antibiotics. A new procedure for the biosynthetic preparation of the uniformly 13C- and 15N-enriched peptaibol is described This compound was isolated from the biomass of the fungus-producer Emericellopsis salmosynnemata strain 336 IMI 58330 obtained upon cultivation in the totally 13C, 15N-labelled complete medium. To prepare such a medium the autolysed biomass and the exopolysaccharides of the obligate methylotrophic bacterium Methylobacillus flagellatus KT were used. This microorganism was grown in totally 13C, 15N-labelled minimal medium containing 13C-methanol and 15N-ammonium chloride as the only carbon and nitrogen sources. Preliminary NMR spectroscopic analysis indicated a high extent of isotope incorporation (> 90%) and led to the complete 13C- and 15N-NMR assignment including the stereospecific assignment of Aib residues methyl groups. The observed pattern of the structurally important secondary chemical shifts of 1H(alpha), 13C=O and 13C(alpha) agrees well with the previously determined structure of zervamicin IIB in methanol solution. PMID:14658801

  9. Effects of weed cover composition on insect pest and natural enemy abundance in a field of Dracaena marginata (Asparagales: Asparagaceae) in Costa Rica.

    Sadof, Clifford S; Linkimer, Mildred; Hidalgo, Eduardo; Casanoves, Fernando; Gibson, Kevin; Benjamin, Tamara J

    2014-04-01

    Weeds and their influence on pest and natural enemy populations were studied on a commercial ornamental farm during 2009 in the Atlantic Zone of Costa Rica. A baseline survey of the entire production plot was conducted in February, along a 5 by 5 m grid to characterize and map initial weed communities of plants, cicadellids, katydids, and armored scales. In total, 50 plant species from 21 families were found. Seven weed treatments were established to determine how weed manipulations would affect communities of our targeted pests and natural enemies. These treatments were selected based on reported effects of specific weed cover on herbivorous insects and natural enemies, or by their use by growers as a cover crop. Treatments ranged from weed-free to being completely covered with endemic species of weeds. Although some weed treatments changed pest abundances, responses differed among arthropod pests, with the strongest effects observed for Caldwelliola and Empoasca leafhoppers. Removal of all weeds increased the abundance of Empoasca, whereas leaving mostly cyperacaeous weeds increased the abundance of Caldwelliola. Weed manipulations had no effect on the abundance of katydid and scale populations. No weed treatment reduced the abundance of all three of the target pests. Differential responses of the two leafhopper species to the same weed treatments support hypotheses, suggesting that noncrop plants can alter the abundance of pests through their effects on arthropod host finding and acceptance, as well as their impacts on natural enemies. PMID:24517852

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

    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

  11. Poly-ethers from Winogradskyella poriferorum: Antifouling potential, time-course study of production and natural abundance

    Dash, Swagatika

    2011-08-01

    A sponge-associated bacterium, Winogradskyella poriferorum strain UST030701-295T was cultured up to 100l for extraction of antifouling bioactive compounds. Five poly-ethers were isolated and partially characterized based on nuclear magnetic resonance (NMR) spectroscopy and mass spectrometry (MS); two of them showed inhibitory effects on biofilm formation of marine bacteria and larval settlement of macro-foulers but did not produce any adverse effects on the phenotypes of zebra fish embryos at a concentration of 5μgml -1. The effect of culture duration on the production of the poly-ethers and the bioactivity of the relevant extracts was monitored over a period of 12days. The total crude poly-ether production increased from day 2 to day 5 and the highest bioactivity was observed on day 3. The poly-ethers were found to be localized in the cellular fraction of the extracts, implying their natural occurrence. The potent bioactivity of these poly-ethers together with their high natural abundance in bacteria makes them promising candidates as ingredients in antifouling applications. © 2011 Elsevier Ltd.

  12. Combined analysis of C-18 unsaturated fatty acids using natural abundance deuterium 2D NMR spectroscopy in chiral oriented solvents.

    Lesot, Philippe; Baillif, Vincent; Billault, Isabelle

    2008-04-15

    The quantitative determination of isotopic (2H/1H)i ratios at natural abundance using the SNIF-NMR protocol is a well-known method for understanding the enzymatic biosynthesis of metabolites. However, this approach is not always successful for analyzing large solutes and, specifically, is inadequate for prochiral molecules such as complete essential unsaturated fatty acids. To overcome these analytical limitations, we use the natural abundance deuterium 2D NMR (NAD 2D NMR) spectroscopy on solutes embedded in polypeptide chiral liquid crystals. This approach, recently explored for measuring (2H/1H)i ratios of small analytes (Lesot, P.; Aroulanda, C.; Billault, I. Anal. Chem. 2004, 76, 2827-2835), is a powerful way to separate the 2H signals of all nonequivalent enantioisotopomers on the basis both of the 2H quadrupolar interactions and of the 2H chemical shift. Two significant advances over our previous work are presented here and allow the complete isotopic analysis of four mono- and polyunsaturated fatty acid methyl esters: methyl oleate (1), methyl linoleate (2), methyl linolenate (3), and methyl vernoleate (4). The first consists of using NMR spectrometers operating at higher magnetic field strength (14.1 T) and equipped with a selective cryoprobe optimized for deuterium nuclei. The second is the development of Q-COSY Fz 2D NMR experiments able to produce phased 2H 2D maps after a double Fourier transformation. This combination of modern hardware and efficient NMR sequences provides a unique tool to analyze the (2H/1H)i ratios of large prochiral molecules (C-18) dissolved in organic solutions of poly(gamma-benzyl-L-glutamate) and requires smaller amounts of solute than previous study on fatty acids. For each compound (1-4), all 2H quadrupolar doublets visible in the 2D spectra have been assigned on the basis of 2H chemical shifts, isotopic data obtained from isotropic quantitative NAD NMR, and by an interspectral comparison of the anisotropic NAD spectra of four

  13. Evaluation of N sub 2 fixation by applying sup 15 N labeled plant material and ammonium sulfate

    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.

  14. Assessment of marine-derived nutrients in the Copper River Delta, Alaska, using natural abundance of the stable isotopes of nitrogen, sulfur, and carbon

    Kline, Thomas C.; Woody, Carol Ann; Bishop, Mary Anne; Powers, Sean P.; Knudsen, E. Eric

    2007-01-01

    We performed nitrogen, sulfur, and carbon stable isotope analysis (SIA) on maturing and juvenile anadromous sockeye and coho salmon, and periphyton in two Copper River delta watersheds of Alaska to trace salmonderived nutrients during 2003–2004. Maturing salmon were isotopically enriched relative to alternate freshwater N, S, and C sources as expected, with differences consistent with species trophic level differences, and minor system, sex, and year-to-year differences, enabling use of SIA to trace these salmon-derived nutrients. Periphyton naturally colonized, incubated, and collected using Wildco Periphtyon Samplers in and near spawning sites was 34S- and 15N-enriched, as expected, and at all freshwater sites was 13C-depleted. At nonspawning and coho-only sites, periphyton 34S and 15N was generally low. However, 34S was low enough at some sites to be suggestive of sulfate reduction, complicating the use of S isotopes. Juvenile salmon SIA ranged in values consistent with using production derived from re-mineralization as well as direct utilization, but only by a minority fraction of coho salmon. Dependency on salmon-derived nutrients ranged from relatively high to relatively low, suggesting a space-limited system. No one particular isotope was found to be superior for determining the relative importance of salmon-derived nutrients.

  15. Cryptic or day-to-day parts of the riverbed N cycle - new challenges for 15N

    Trimmer, Mark; Ouyang, Liao; Lansdown, Katrina

    2016-04-01

    The discovery of anaerobic ammonium oxidation (anammox) not only changed our understanding of the nitrogen cycle in aquatic ecosystems but it also undermined some of the key 15N techniques used to study it. Reformulations of principle equations and the development of new 15N2 and 15N2O techniques enabled the simultaneous quantification of N2 production by anammox and denitrification in mainly soft, cohesive sediments where redox gradients are clearly defined and solute exchanged governed by diffusion. At the heart of the application of 15N, for the quantification of natural 14N cycling, is the key assumption that the respective pools of 15N and 14N are evenly mixed and that both are cycled without bias towards each other. Recent evidence, however, from a variety of aquatic ecosystems, suggests that this may not be the case. For example, organic N may be oxidised directly to N2 gas without ever mixing with the inorganic pool or inorganic intermediates (e.g. nitrite) are 'shunted' internally and also fail to mix evenly with the applied tracer pool. Our most recent work in permeable, oxic gravel riverbeds presents some particular challenges to the application of 15N. In these systems, a tight coupling between aerobic nitrification and anaerobic N2 production - in the presence of 100

  16. Influence of niche differentiation on the abundance of methanogenic archaea and methane production potential in natural wetland ecosystems across China

    D. Liu

    2010-10-01

    Full Text Available Methane (CH4 emissions from natural wetland ecosystems exhibit large spatial variability. To understand the underlying factors that induce differences in CH4 emissions from natural wetlands around China, we measured the CH4 production potential and the abundance of methanogenic archaea in vertical profile soils sampled from the Poyang wetland in the subtropical zone, the Hongze wetland in the warm temperate zone, the Sanjiang marsh in the cold temperate zone, and the Ruoergai peatland in the Qinghai-Tibetan Plateau. The top soil layer had the highest population of methanogens (1.07−8.29×109 cells g−1 soil in all wetlands except the Ruoergai peatland and exhibited the maximum CH4 production potential measured at the mean in situ summer temperature. There is a significant logarithmic correlation between the abundance of methanogenic archaea and the soil organic carbon (R2=0.718, P<0.001, n=13 and between the abundance of methanogenic archaea and the total nitrogen concentrations (R2=0.758, P<0.001, n=13 in wetland soils. This indicates that the amount of soil organic carbon may affect the population of methanogens in wetland ecosystems. While the CH4 production potential is not significantly related to methanogen population (R2=0.011, P>0.05, n=13, it is related to the dissolved organic carbon concentration (R2=0.305, P=0.05, n=13. This suggests that the methanogen population is not an effective index for predicting the CH4 production in wetland ecosystems. The CH4 production rate of the top soil layer increases with increasing latitude, from 274 μg CH4 kg−1 soil d−1 in the Poyang wetland to 665 μg CH4 kg−1 soil d−1 in the Carex lasiocarpa

  17. The determination of minor isotope abundances in naturally occurring uranium materials. The tracing power of isotopic signatures for uranium

    The mass spectrometric determination of minor abundant isotopes, 234U and 236U in naturally occurring uranium materials requires instruments of high abundance sensitivity and the use of highly sensitive detection systems. In this study the thermal ionisation mass spectrometer Finnigan MAT 262RPQ was used. It was equipped with 6 Faraday cups and a Secondary Electron Multiplier (SEM), which was operated in pulse counting mode for the detection of extremely low ion currents. The dynamic measurement range was increased considerably combining these two different detectors. The instrument calibration was performed carefully. The linearity of each detector, the deadtime of the ion counting detector, the detector normalisation factor, the baseline of each detector and the mass discrimination in the ion source were checked and optimised. A measurement technique based on the combination of a Gas Source Mass Spectrometry (GSMS) and a Thermal Ionisation Mass Spectrometry (TIMS) was developed for the accurate determination of isotopic composition in naturally occurring uranium materials. Because the expected ratio of n(234U)/n(238U) exceeded the dynamic measurement range of the Faraday detectors of the TIMS instrument, an experimental design using a combination of two detectors was developed. The n(234U)/n(235U) and n(236U)/n(235U) ratios were determined using ion counting in combination with the decelerating device. The n(235U)/n(238U) ratio was determined by the Faraday detector. This experimental design allowed the detector cross calibration to be circumvented. Precisions of less than 1 percent for the n(234U)/n(235U) ratios and 5-25 percent for the n(236U)/n(235U) ratios were achieved. The purpose of the study was to establish a register of isotopic signatures for natural uranium materials. The amount ratio, and isotopic composition of 18 ore concentrates, collected by the International Atomic Energy Agency (IAEA) from uranium milling and mining facilities (Australia

  18. The determination of minor isotope abundances in naturally occurring uranium materials. The tracing power of isotopic signatures for uranium

    Ovaskainen, R

    1999-11-01

    The mass spectrometric determination of minor abundant isotopes, {sup 234}U and {sup 236}U in naturally occurring uranium materials requires instruments of high abundance sensitivity and the use of highly sensitive detection systems. In this study the thermal ionisation mass spectrometer Finnigan MAT 262RPQ was used. It was equipped with 6 Faraday cups and a Secondary Electron Multiplier (SEM), which was operated in pulse counting mode for the detection of extremely low ion currents. The dynamic measurement range was increased considerably combining these two different detectors. The instrument calibration was performed carefully. The linearity of each detector, the deadtime of the ion counting detector, the detector normalisation factor, the baseline of each detector and the mass discrimination in the ion source were checked and optimised. A measurement technique based on the combination of a Gas Source Mass Spectrometry (GSMS) and a Thermal Ionisation Mass Spectrometry (TIMS) was developed for the accurate determination of isotopic composition in naturally occurring uranium materials. Because the expected ratio of n({sup 234}U)/n({sup 238}U) exceeded the dynamic measurement range of the Faraday detectors of the TIMS instrument, an experimental design using a combination of two detectors was developed. The n({sup 234}U)/n({sup 235}U) and n({sup 236}U)/n({sup 235}U) ratios were determined using ion counting in combination with the decelerating device. The n({sup 235}U)/n({sup 238}U) ratio was determined by the Faraday detector. This experimental design allowed the detector cross calibration to be circumvented. Precisions of less than 1 percent for the n({sup 234}U)/n({sup 235}U) ratios and 5-25 percent for the n({sup 236}U)/n({sup 235}U) ratios were achieved. The purpose of the study was to establish a register of isotopic signatures for natural uranium materials. The amount ratio, and isotopic composition of 18 ore concentrates, collected by the International

  19. Variability in δ15N of intertidal brown algae along a salinity gradient: Differential impact of nitrogen sources

    While it is generally agreed that δ15N 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 δ15N 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 δ15N-DIN, along with salinity and temperature in seawater were also studied to address the sources of such variability. Macroalgal δ15N and nutrient concentrations decreased from estuarine to marine waters, suggesting larger dominance of anthropogenic nitrogen sources in the estuary. However, δ15N 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 δ15N 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 δ15N indicates N sources along a salinity gradient. • δ15N 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

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

    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. Importance of Arboreal Cyanolichen Abundance to Nitrogen Cycling in Sub-Boreal Spruce and Fir Forests of Central British Columbia, Canada

    Ania Kobylinski

    2015-07-01

    Full Text Available The importance of N2-fixing arboreal cyanolichens to the nitrogen (N-balance of sub-boreal interior hybrid spruce (Picea glauca × engelmannii and subalpine fir (Abies lasiocarpa forests was examined at field sites in central BC, Canada. Host trees were accessed by a single-rope climbing technique and foliage as well as arboreal macrolichen functional groups were sampled by branch height in eight random sample trees from each of two high (High Cyano and two low (Low Cyano cyanolichen abundance sites for a total of 32 sample trees. Natural abundances of stable isotopes of N (15N, 14N and carbon (13C, 12C were determined for aggregate host tree and epiphytic lichen samples, as well as representative samples of upper organic and soil horizons (Ae and Bf from beneath host trees. As expected, N2-fixing cyanolichens had 2–6-fold greater N-contents than chlorolichens and a δ15N close to atmospheric N2, while foliage and chlorolichens were more depleted in 15N. By contrast, soils at all trees and sites were 15N-enriched (positive δ15N, with declining (not significant δ15N with increased tree-level cyanolichen abundance. Lichen functional groups and tree foliage fell into three distinct groups with respect to δ13C; the tripartite cyanolichen Lobaria pulmonaria (lightest, host-tree needles (intermediate, and bipartite cyanolichens, hair (Alectoria and Bryoria spp. and chlorolichens (heaviest. Branch height of host trees was an effective predictor of needle δ13C. Our results showed a modest positive correlation between host tree foliage N and cyanolichen abundance, supporting our initial hypothesis that higher cyanolichen abundances would elevate host tree foliar N. Further study is required to determine if high cyanolichen abundance enhances host tree and/or stand-level productivity in sub-boreal forests of central BC, Canada.

  2. Abundance of non-native crabs in intertidal habitats of New England with natural and artificial structure.

    Lovely, Christina M; O'Connor, Nancy J; Judge, Michael L

    2015-01-01

    Marine habitats containing complex physical structure (e.g., crevices) can provide shelter from predation for benthic invertebrates. To examine effects of natural and artificial structure on the abundance of intertidal juvenile crabs, 2 experiments were conducted in Kingston Bay, Massachusetts, USA, from July to September, 2012. In the first experiment, structure was manipulated in a two-factor design that was placed in the high intertidal for 3 one-week periods to test for both substrate type (sand vs. rock) and the presence or absence of artificial structure (mesh grow-out bags used in aquaculture, ∼0.5 m(2) with 62 mm(2) mesh openings). The Asian shore crab, Hemigrapsus sanguineus, and small individuals of the green crab, Carcinus maenas, were observed only in the treatments of rocks and mesh bag plus rocks. Most green crabs were small (bags placed on a muddy sand substrate in the low intertidal zone: mesh grow-out bags without shells, grow-out bags with oyster shells, and grow-out bags containing live oysters. Replicate bags were deployed weekly for 7 weeks in a randomized complete block design. All crabs collected in the bags were juvenile C. maenas (1-15 mm carapace width), and numbers of crabs differed 6-fold among treatments, with most crabs present in bags with live oysters (29.5 ± 10.6 m(-2) [mean ± S.D.]) and fewest in bags without shells (4.9 ± 3.7 m(-2)). Both C. maenas and H. sanguineus occurred in habitats with natural structure (cobble rocks). The attraction of juvenile C. maenas to artificial structure consisting of plastic mesh bags containing both oyster shells and living oysters could potentially impact oyster aquaculture operations. PMID:26401456

  3. Mapping the dynamics of ligand reorganization via 13CH3 and 13CH2 relaxation dispersion at natural abundance

    Flexible ligands pose challenges to standard structure-activity studies since they frequently reorganize their conformations upon protein binding and catalysis. Here, we demonstrate the utility of side chain 13C relaxation dispersion measurements to identify and quantify the conformational dynamics that drive this reorganization. The dispersion measurements probe methylene 13CH2 and methyl 13CH3 groups; the latter are highly prevalent side chain moieties in known drugs. Combining these side chain studies with existing backbone dispersion studies enables a comprehensive investigation of μs-ms conformational dynamics related to binding and catalysis. We perform these measurements at natural 13C abundance, in congruence with common pharmaceutical research settings. We illustrate these methods through a study of the interaction of a phosphopeptide ligand with the peptidyl-prolyl isomerase, Pin1. The results illuminate the side-chain moieties that undergo conformational readjustments upon complex formation. In particular, we find evidence that multiple exchange processes influence the side chain dispersion profiles. Collectively, our studies illustrate how side-chain relaxation dispersion can shed light on ligand conformational transitions required for activity, and thereby suggest strategies for its optimization

  4. Natural Abundance 43Ca NMR as a Tool for Exploring Calcium Biomineralization: Renal Stone Formation and Growth

    Bowers, Geoffrey M.; Kirkpatrick, Robert J.

    2011-12-07

    Renal stone diseases are a global health issue with little effective therapeutic recourse aside from surgery and shock-wave lithotripsy, primarily because the fundamental chemical mechanisms behind calcium biomineralization are poorly understood. In this work, we show that natural abundance 43Ca NMR at 21.1 T is an effective means to probe the molecular-level Ca2+ structure in oxalate-based kidney stones. We find that the 43Ca NMR resonance of an authentic oxalate-based kidney stone cannot be explained by a single pure phase of any common Ca2+-bearing stone mineral. Combined with XRD results, our findings suggest an altered calcium oxalate monohydrate-like Ca2+ coordination environment for some fraction of Ca2+ in our sample. The evidence is consistent with existing literature hypothesizing that nonoxalate organic material interacts directly with Ca2+ at stone surfaces and is the primary driver of renal stone aggregation and growth. Our findings show that 43Ca NMR spectroscopy may provide unique and crucial insight into the fundamental chemistry of kidney stone formation, growth, and the role organic molecules play in these processes.

  5. Bird Species Abundance and Their Correlationship with Microclimate and Habitat Variables at Natural Wetland Reserve, Peninsular Malaysia

    Muhammad Nawaz Rajpar; Mohamed Zakaria

    2011-01-01

    Birds are the most conspicuous and significant component of freshwater wetland ecosystem. Presence or absence of birds may indicate the ecological conditions of the wetland area. The objectives of this study were to determine bird species abundance and their relationship with microclimate and habitat variables. Distance sampling point count method was applied for determining species abundance and multiple regressions was used for finding relationship between bird species abundance, microclima...

  6. Isotopic enrichment of 15N by ionic exchange cromatography

    The ionic exchange chromatographic method in columns of resin which is employed in the study of isotopic enrichment of 15N is presented. Determinations are made of the isotopic separation constant for the exchange of isotopes 15N and 14N in the equilibrium involving ammonium hidroxide in the solution phase and ions NH4+ adsorbed in cationic resins: Dowex 50W-X8 and X12, 100-200 mesh. Experiments are also conducted for determination of height of theoretical plates for situations of equilibrium of the NH4+ band in two systems of resin's columns aimed at estimating the experimental conditions used. The isotopic analyses of nitrogen are carried out by mass spectrometry

  7. Marking Drosophila suzukii (Diptera: Drosophilidae) With Rubidium or 15N.

    Klick, J; Yang, W Q; Bruck, D J

    2015-06-01

    Drosophila suzukii Matsumura (Diptera: Drosophilidae) has caused significant economic damage to berry and stone fruit production regions. Markers that are systemic in plants and easily transferred to target organisms are needed to track D. suzukii exploitation of host resources and trophic interactions. High and low concentrations of the trace element, rubidium (Rb), and the stable isotope, 15N, were tested to mark D. suzukii larvae feeding on fruits of enriched strawberry plants grown in containers under greenhouse conditions. Fly marker content and proportion of flies marked 1, 7, and 14 d after emergence from enriched fruits and fly dry mass were analyzed. Nearly 100% of the flies analyzed 14 d after emerging from 15N-enriched plants were marked, whereas only 30-75% and 0-3% were marked 14 d after emerging from high and low Rb concentration plants, respectively. Rapid Rb decay, strong 15N persistence, and the economics of using these markers in the field to elucidate D. suzukii pest ecology are discussed. PMID:26470275

  8. Geomorphic control on the δ15N of mountain forests

    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.

  9. Absorption of ammonium sulphate 15N by coffee plants

    The objective of this study was to quantify the absorption of ammonium sulphate 15N by coffee plants. Treatments consisted of five sub-plots of 9 plants, of which the three central ones received 280 kg ha-1 of 15N, 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 % 15N. 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)

  10. COVALENT BINDING OF REDUCED METABOLITES OF [15N3] TNT TO SOIL ORGANIC MATTER DURING A BIOREMEDIATION PROCESS ANALYZED BY 15N NMR SPECTROSCOPY. (R826646)

    Evidence is presented for the covalent binding ofbiologically reduced metabolites of 2,4,6-15N3-trinitrotoluene(TNT) to different soil fractions (humic acids, fulvicacids, and humin) using liquid 15N NMR spectroscopy. Asilylation p...

  11. Dynamic of N fertilizers: urea (15 N) and aqua ammonia (15 N) incorporated to the sugar cane soil. Final report

    The dynamic of N fertilizers, urea and aqua ammonia, in the soil of sugar cane crops are studied with an emphasis on the horizontal and vertical moving. The nitrogen routing from urea and aqua ammonia sources, by isotopic technique with 15 N in relation to the leaching, volatilization and extraction by the cultivation and residue of N immobilized manure in the soil with sugar cane plantation is also analysed. (C.G.C.)

  12. Conformational study of C8 diazocine turn mimics using 3JCH coupling constants with 13C in natural abundance

    The conformations of two diazocine turn mimics, which were later incorporated into GPIIb/IIIa peptide antagonists, were investigated using nuclear magnetic resonance techniques. The two compounds, methyl (2,5-dioxo-3-(S)-(3-ω-tosylguanidino-propyl)-4-methyl-octahydro-1,4-dazocin-1-yl)acetate (1) and methyl (2,5-dioxo-3-(S)-(3-ω-tosyl-guanidino-propyl)-octahydro-1,5-diazocin-1-yl)acetate (2), differ only in their substituent at the diazocine position 4 nitrogen, yet this substitution results in a marked difference in the affinity of the resulting analogs for the GPIIb/IIIa receptor. It was of interest to determine if the difference observed in the antagonistic potency between these analogs was related to constitutional or, perhaps, conformational differences. The backbone conformations of these two molecules can be determined by measuring vicinal coupling constants along the trimethylene portion of the C8 ring backbone and by measuring interproton NOE intensities between the diazocine methine proton and the protons of the trimethylene group. For compound 1, 3JHH values measured from a P.E.COSY spectrum and interproton distances calculated from ROESY buildup curves indicated the presence of a single C8 ring backbone conformation where the trimethylene bridge adopted a staggered conformation and the Hα1 and Hγ1 protons of the trimethylene group were 2.2 A from the methine proton. For compound 2, however, partial overlap of the central Hβ1 and Hβ2 protons made it impossible to measure 3JHH values from the P.E.COSY spectrum. We therefore used a 13C-filtered TOCSY experiment to measure the 3JCH values in both compounds 1 and 2. These heteronuclear vicinal coupling constants measured with 13C in natural abundance in conjunction with measured interproton NOE intensities indicate that these compounds share a common C8 ring backbone conformation

  13. Cumulative fission yields of short-lived isotopes under natural-abundance-boron-carbide-moderated neutron spectrum

    Finn, Erin C.; Metz, Lori A.; Greenwood, Lawrence R.; Pierson, Bruce; Wittman, Richard S.; Friese, Judah I.; Kephart, Rosara F.

    2015-04-09

    The availability of gamma spectroscopy data on samples containing mixed fission products at short times after irradiation is limited. Due to this limitation, data interpretation methods for gamma spectra of mixed fission product samples, where the individual fission products have not been chemically isolated from interferences, are not well-developed. The limitation is particularly pronounced for fast pooled neutron spectra because of the lack of available fast reactors in the United States. Samples containing the actinide isotopes 233, 235, 238U, 237Np, and 239Pu individually were subjected to a 2$ pulse in the Washington State University 1 MW TRIGA reactor. To achieve a fission-energy neutron spectrum, the spectrum was tailored using a natural abundance boron carbide capsule to absorb neutrons in the thermal and epithermal region of the spectrum. Our tailored neutron spectrum is unique to the WSU reactor facility, consisting of a soft fission spectrum that contains some measurable flux in the resonance region. This results in a neutron spectrum at greater than 0.1 keV with an average energy of 70 keV, similar to fast reactor spectra and approaching that of 235U fission. Unique fission product gamma spectra were collected from 4 minutes to 1 week after fission using single-crystal high purity germanium detectors. Cumulative fission product yields measured in the current work generally agree with published fast pooled fission product yield values from ENDF/B-VII, though a bias was noted for 239Pu. The present work contributes to the compilation of energy-resolved fission product yield nuclear data for nuclear forensic purposes.

  14. Evaluating microbial carbon sources in Athabasca oil sands tailings ponds using natural abundance stable and radiocarbon isotopes

    Ahad, J. M.; Pakdel, H.

    2013-12-01

    Natural abundance stable (δ13C) and radiocarbon (Δ14C) isotopes of phospholipid fatty acids (PLFAs) were used to evaluate the carbon sources utilized by the active microbial populations in surface sediments from Athabasca oil sands tailings ponds. The absence of algal-specific PLFAs at three of the four sites investigated, in conjunction with δ13C signatures for PLFAs that were generally within ~3‰ of that reported for oil sands bitumen (~ -30‰), indicated that the microbial communities growing on petroleum constituents were dominated by aerobic heterotrophs. The Δ14C values of PLFAs ranged from -906 to -586‰ and pointed to a significant uptake of fossil carbon (up to ~90% of microbial carbon derived from petroleum), particularly in PLFAs (e.g., cy17:0 and cy19:0) often associated with petroleum hydrocarbon degrading bacteria. The comparatively higher levels of 14C in other, less specific PLFAs (e.g., 16:0) indicated the preferential uptake of younger organic matter by the general microbial population (~50-80% of microbial carbon derived from petroleum). Since the main carbon pools in tailings sediment were essentially 'radiocarbon dead' (i.e., no detectable 14C), the principal source for this modern carbon is considered to be the Athabasca River, which provides the bulk of the water used in the bitumen extraction process. The preferential uptake of the minor amount of young and presumably more biodegradable material present in systems otherwise dominated by recalcitrant petroleum constituents has important implications for remediation strategies. On the one hand, it implies that mining-related organic contaminants could persist in the environment long after tailings pond reclamation has begun. Alternatively, it may be that the young, labile organic matter provided by the Athabasca River plays an important role in stimulating or supporting the microbial utilization of petroleum carbon in oil sands tailings ponds via co-metabolism or priming processes

  15. Estimation of the endogenous N proportions in ileal digesta and faeces in 15N-labelled pigs

    4 castrated male pigs 40 kg fitted with simple 'T' cannulas in the terminal ileum were given 15N-labelled ammonium salts, added to a low protein diet, for 6 days. Excretion of 15N in urine and feces was monitored daily throughout the labelling and subsequent experimental periods. During the experimental period the pigs were given a diet based on wheat and fish meal, supplemented with varying levels of partially hydrolyzed straw meal to give crude fiber contents ranging from 40 to 132 g/kg. After adaptation to the particular levels of straw meal, feces and ileal digesta were collected during successive 24 h periods. N digestibility values were determined by the chromium oxide ratio method. The retention of 15N-labelled non-specific N was 0.46 of the dose given. The validity of using urine values as a measure of 15N abundance in endogenous N was demonstrated by the similarity of 15N abundance in urine immediately before slaughter at the end of the experiment and in the digestive secretory organs thereafter. The average amount of endogenous N passing the terminal ileum was 3.4 g/day or 0.30-0.50 of total ileal N flow. This was not affected by dietary fiber level. The proportion of fecal N which was of endogenous origin was similar to that in ileal digesta, suggesting similar utilization of endogenous and residual dietary N by hindgut bacteria. Half the endogenous N entering the large intestine was reabsorbed there. Increasing dietary crude fiber from 40 to 132 g/kg increased fecal endogenous N excretion from 1.3 to 2.0 g/animal and day. (author)

  16. Isotope 15N for agronomic research: an overview

    Fertilizer N recovery determined by isotope labelling technique using 15N enriched fertilizer was compared with apparent recovery of N obtained by the difference method and the extent of error associated with it was compared in six vegetable crops. In the difference method, fertilizer N recovery was overestimated and the error ranged from 3 per cent in tomato to 94 per cent in chilli, whereas uptake of soil N by the difference method was underestimated and the error ranged from 2 per cent in tomato to 64 per cent in chilli. One of the main reasons for the error was the degree of response to N due to increase in dry matter yield

  17. Growth, development, and fertilizer-15N recovery by the coffee plant

    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 15N 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-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 15N 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)

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

    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)

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

    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.

  20. An electron-scattering study of 15N

    An electron scattering experiment on 15N was performed in order to test the results of two different shell-model approaches, both performed in a full (0+2)ℎω space, one employing a phenomenologic interaction which is valid throughout the 1p shell, the other an interaction whose parameters were adjusted to fit the excitation energies of a number of states. The experiment was carried out at the high-energy electron-scattering facility of NIKHEF-k. A room temperature gas target was employed. Data were taken at forward angles in the range q=0.35 - 3.17 fm-1. Results are presented for negative-parity states up to an excitation energy of 13 MeV. The differences in groundstate charge density between 15N and the neighbouring nuclei 16O and 14N are compared with results of shell-model calculations. In ch. 5 the transition charge-densities to the excited negative-parity states are presented and compared with shell model calculations. 52 refs.; 18 figs.; 5 tabs

  1. Fuzzy logic control of 15 N separation plant

    The process of 15 N separation by chemical exchange in Nitrox system is automatically maintained in the optimal operation conditions using a computerized control. The automatic control leads to a maximum production of 15 N with a minimum of raw materials and energy consumption.. The control objective was achieved by considering two forms of knowledge: 1. objective knowledge, which uses the control engineering based on mathematical model of the separation process; 2. subjective knowledge, which represents linguistic information, very difficult to quantify using classical mathematics - e.g., the rule of HNO3 solution and SO2 flow rates adjustment in order to maintain a proper height and position of chemical reaction zone in the product refluxer. The above mentioned two types of knowledge were coordinated in a logical way using fuzzy logic control system which has the possibility to handle simultaneously numerical data and linguistic knowledge. In order to map input data vector into a scalar output, i.e., numbers to numbers a front-end 'fuzzifier' and a rear-end 'defuzzifier' was added to the usual fuzzy logic model. The inference engine of the control system maps the input fuzzy set into the output one. The inferential procedure maintains the isotope separation process in the optimal operation conditions. (author)

  2. N-15 NMR spectra of naturally abundant nitrogen in soil and aquatic natural organic matter samples of the International Humic Substances Society

    Thorn, Kevin A.; Cox, Larry G.

    2009-02-28

    The naturally abundant nitrogen in soil and aquatic NOM samples from the International Humic Substances Society has been characterized by solid state CP/MAS ¹⁵N NMR. Soil samples include humic and fulvic acids from the Elliot soil, Minnesota Waskish peat and Florida Pahokee peat, as well as the Summit Hill soil humic acid and the Leonardite humic acid. Aquatic samples include Suwannee River humic, fulvic and reverse osmosis isolates, Nordic humic and fulvic acids and Pony Lake fulvic acid. Additionally, Nordic and Suwannee River XAD-4 acids and Suwannee River hydrophobic neutral fractions were analyzed. Similar to literature reports, amide/aminoquinone nitrogens comprised the major peaks in the solid state spectra of the soil humic and fulvic acids, along with heterocyclic and amino sugar/terminal amino acid nitrogens. Spectra of aquatic samples, including the XAD-4 acids, contain resolved heterocyclic nitrogen peaks in addition to the amide nitrogens. The spectrum of the nitrogen enriched, microbially derived Pony Lake, Antarctica fulvic acid, appeared to contain resonances in the region of pyrazine, imine and/or pyridine nitrogens, which have not been observed previously in soil or aquatic humic substances by ¹⁵N NMR. Liquid state ¹⁵N NMR experiments were also recorded on the Elliot soil humic acid and Pony Lake fulvic acid, both to examine the feasibility of the techniques, and to determine whether improvements in resolution over the solid state could be realized. For both samples, polarization transfer (DEPT) and indirect detection (¹H–¹⁵N gHSQC) spectra revealed greater resolution among nitrogens directly bonded to protons. The amide/aminoquinone nitrogens could also be observed by direct detection experiments.

  3. 15N in tree rings as a bio-indicator of changing nitrogen cycling in tropical forests: an evaluation at three sites using two sampling methods

    Peter evan der Sleen

    2015-04-01

    Full Text Available Anthropogenic nitrogen deposition is currently causing a more than twofold increase of reactive nitrogen input over large areas in the tropics. Elevated 15N abundance15N in the growth rings of some tropical trees has been hypothesized to reflect an increased leaching of 15N-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 δ15N 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 pit to the bark across the stem of 28 large trees (the ‘radial’ method. In the second, δ15N values were compared across a fixed diameter (the ‘fixed-diameter’ method. We sampled 400 trees that differed widely in size, but measured δ15N 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 δ15N values over time with an explicit control for the potential size-effects on δ15N values. We found a significant increase of tree-ring δ15N across the stem radius of large trees from Bolivia and Cameroon, but no change in tree-ring δ15N values over time was found in any of the study sites when controlling for tree size. This suggests that radial trends of δ15N 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 δ15N 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 δ15N values can be properly

  4. Application of capillary gas chromatography-reaction interface/mass spectrometry to the selective detection of 13C-, 15N-, 2H-, and 14C-labeled drugs and their metabolites

    A novel reaction interface/mass spectrometer (RIMS) technique has been applied to the selective detection of 13C-, 15N-, 2H-, and 14C-labeled phenytoin and its metabolites in urine following separation by capillary gas chromatography. The microwave-powered reaction interface converts materials from their original forms into small molecules whose mass spectra serve to identify and quantify the nuclides. The presence of each element is followed by monitoring the isotopic variants of CO2, NO, H2, or CH4 that are produced by the reaction interface. Chromatograms showing only enriched 13C and 15N were produced using the net 13CO2 or 15NO signal derived by subtracting the abundance of naturally occurring isotopes from the observed M + 1 signal. When hydrogen was used as a reactant gas, a selective chromatogram of 2H (D) was obtained by measuring HD at m/Z 3.0219, and a chromatogram showing 14C was obtained by measuring 14CH4 at m/Z 18.034 with a high resolution. For a stable isotope detection, metabolites representing less than 1.5% of the total labeled compounds could be detected in the chromatogram. Detection limits of 170 pCi/mL (34 pCi on column that is equivalent to 187 pg) of a 14C- labeled metabolite was detected. To identify many of these labeled peaks (metabolites), the chromatographic analysis was repeated with the reaction interface turned off and mass spectra obtained at the retention times found in the RIMS experiment. In addition to the ability of GC-RIMS to detect the presence of 13C-, 15N-, and 2H- (D), it can also quantify the level of enrichment. Enrichment of 13C and 15N is quantified by measuring the ratio of excess 13CO2 to total 12CO2 or excess 15NO to total 14NO

  5. Effect of fed-batch on synthesis of 15N-L-tryptophan from precursor fermentation

    Using Candida utilis AS60 as 15N-L-tryptophan producing strain, the influence by different feeding modes of glucose, 15N-(NH4)2SO4 and 15N-anthranilic acid was studied. The results of these experiments show that the yield of 15N-L-tryptophan was 3.073 g/L by addition of 50 g/L of glucose, 2.1 g/L of 15N-(NH4)2SO4 and 1.5 g/L of 15N-anthranilic acid after 36 h of fermentation. (authors)

  6. Bird Species Abundance and Their Correlationship with Microclimate and Habitat Variables at Natural Wetland Reserve, Peninsular Malaysia

    Muhammad Nawaz Rajpar

    2011-01-01

    Full Text Available Birds are the most conspicuous and significant component of freshwater wetland ecosystem. Presence or absence of birds may indicate the ecological conditions of the wetland area. The objectives of this study were to determine bird species abundance and their relationship with microclimate and habitat variables. Distance sampling point count method was applied for determining species abundance and multiple regressions was used for finding relationship between bird species abundance, microclimate and habitat variables. Bird species were monitored during November, 2007 to January, 2009. A total of 8728 individual birds comprising 89 species and 38 families were detected. Marsh Swamp was swarmed by 84 species (69.8% followed open water body by 55 species (17.7% and lotus swamp by 57 species (12.6%. Purple swamphen Porphyrio porphyrio (9.1% of all detections was the most abundant bird species of marsh swamp, lesser whistling duck—Dendrocygna javanica (2.3% was dominant species of open water body and pink-necked green pigeon—Treron vernans (1.7% was most common species of lotus swamp. Results revealed that the habitat characteristics such as vegetation composition (i.e. emergent and submerged vegetations, grasses, shrubs, and trees, vegetation structures (tree diameter and height and microclimate variables (temperature, relative humidity and light intensity were the key factors that influenced the distribution, diversity and density of the wetland bird species. This study also revealed that the wetland bird species have adapted a fairly unique set of microhabitat and microclimate conditions.

  7. Natural abundance of N-15 and C-13 in fish tissues and the use of stable isotopes as dietary protein tracers in rainbow trout and gilthead sea bream

    Beltran, M; Fernandez-borras, J.; Medale, Francoise; Perez-sanchez, J.; Kaushik, Sadasivam; Blasco, J.

    2009-01-01

    For developing efficient diets, two sets of experiments examined whether the use and allocation of dietary protein can be traced by labelling with stable isotopes (N-15 and C-13) in two culture fish (Oncorhynchus mykiss and Sparus aurata). In the first experiment, natural abundance and tissue distribution of these isotopes were determined, by measuring the delta C-13 and delta N-15 values by isotopic ratio mass spectrometry, in fingerlings (14-17 g) adapted to diets differing in the percentag...

  8. Spatiotemporal changes in flying insect abundance and their functional diversity as a function of distance to natural habitats in a mass flowering crop

    Geslin, Benoît; Oddie, Melissa; Folschweiller, Morgane; Legras, Gaëlle; Seymour, Colleen L.; van Veen, F.J.Frank; Thébault, Elisa

    2016-01-01

    International audience To meet the dietary requirements of a burgeoning human population, the demand for animal-dependent crops continues to grow. To meet the demand, intensive farming practices are used. The gains in food production associated with agricultural intensification may be offset by its detrimental effects on pollinator populations through natural habitat fragmentation and pesticide use. Abundance and species richness of pollinators have been found to decrease with increasing d...

  9. (H)N(COCA)NH and HN(COCA)NH experiments for 1H-15N backbone assignments in 13C/15N-labeled proteins

    Bracken, Clay; Palmer, Arthur G. III [Columbia University, Department of Biochemistry and Molecular Biophysics (United States); Cavanagh, John [New York State Department of Health, NMR Structural Biology Facility, Wadsworth Center (United States)

    1997-01-15

    Triple resonance HN(COCA)NH pulse sequences for correlating 1H(i), 15N(i),1H(i-1), and 15N(i-1) spins that utilize overlapping coherence transfer periods provide increased sensitivity relative to pulse sequences that utilize sequential coherence transfer periods. Although the overlapping sequence elements reduce the overall duration of the pulse sequences, the principal benefit derives from a reduction in the number of 180 deg. pulses. Two versions of the technique are presented: a 3D (H)N(COCA)NH experiment that correlates 15N(i),1H(i-1), and 15N(i-1) spins, and a 3D HN(COCA)NH experiment that correlates 1H(i), 15N(i),1H(i-1), and 15N(i-1) spins by simultaneously encoding the 1H(i) and 15N(i) chemical shifts during the t1 evolution period. The methods are demonstrated on a 13C/15N-enriched sample of the protein ubiquitin and are easily adapted for application to 2H/13C/15N-enriched proteins.

  10. Applications of the 18O-isotope shift on 13C and 15N nuclear magnetic resonance spectroscopy to the study of bioorganic reaction mechanisms

    The study of reactions involving the formation and cleavage of carbon-oxygen or nitrogen-oxygen bonds has been significantly aided by recent demonstrations of the generality and characteristics of the 18O-isotope shift in 13C and 15N nuclear magnetic resonance spectroscopy. In many instances, the magnitudes of the 18O-induced isotopic shifts are sufficiently large as to permit the use of even modest NMR instrumentation and natural abundance 13C. Studies involving less soluble compounds, higher molecular weight materials or relatively rapid reactions may often be carried out using 13C enrichment. Because NMR spectroscopy is non-destructive, it has proven to be extremely useful in the study of natural product biosynthetic pathways. Another area where important applications are being made is in the study of enzymatic and non-enzymatic reaction mechanisms. The characteristics of the 18O isotope shift in 13C NMR spectroscopy are reviewed. Several examples from the work of other groups in the area of natural product biosynthesis are briefly mentioned. This is followed by a number of illustrative applications in the area of bioorganic and enzymatic reaction mechanism that have been examined in our laboratory. The enzymatic examples include acid phosphatases, epoxide hydratase, acetylcholinesterase and asparaginase. 20 refs.; 1 figure

  11. Distribution of complemented 15N - (NH4)2SO4 in an ethanolic fermentation process on insolube-N and solube-N fractions

    Looking for stillage labeling with 15N for further utilization in studies of mineral fertilization of sugar-cane, 15N-(NH4)2SO4 (43.5ppm, 45.401 atoms% 15N) was supplemented in a single fermentative cycle, in a laboratory scale. A nitrogen fractionation was made between insoluble-N and soluble-N in several componentes of the fermentative process (yeast, sugar-cane juice, centrifugate wine, centrifugate yeast and stillage) with the objective of studying the added nitrogen distribution and its isotopic abundance composition. The nitrogen fractionation, and the isotopic analysis by mass spectrometry of 15N, in the fractions of the several components of the fermentative process, showed 81.1% of N recovery, being 3.2% in stillage and mainly in a soluble-N fraction (71.4%), and the rest found in centrifugate yeast (77.9%), distributed mainly in a insoluble-N fraction (92.0%). Desuniform isotopic label was found in stillage, between soluble-N (1.333 atoms%15N) and insoluble-N fractions (0.744 atoms% 15N). Means to improve the isotopic uniformity in these fractions is discussed. (autor)

  12. A one-two punch: Joint effects of natural gas abundance and renewables on coal-fired power plants

    Harrison Fell; Daniel T. Kaffine

    2014-01-01

    Since 2007, coal-fired electricity generation in the US has declined by a stunning 25%. At the same time, natural gas-fired generation and wind generation have dramatically increased due to technological advances and policy interventions. We examine the joint impact of natural gas prices and wind generation on coal generation, with a particular focus on the interaction between low natural gas prices and increased wind generation. Exploiting detailed daily unit-level data, we estimate the resp...

  13. Metabolic studies in colostomized laying hens using 15N-labelled wheat. 4

    3 colostomized laying hybrids received over 4 days a dosage of 672 mg 15N excess (15N'), 20.3 mg lysine 15N', 23.0 mg histidine 15N' and 66.7 mg arginine 15N' with a ration customary in production. After feeding the same unlabelled ration for another 4 days the hens were killed and the N content of the blood as well as of its fractions (cells, plasma, free amino acids of the plasma) was determined. The 15N' was determined in the total blood, the corpuscles, the plasma, the nonprotein-N (NPN) fraction as well as in the amino acids lysine, histidine and arginine. The average amount of the blood cell N in the total blood N was 58.5% and that of the plasma 40.3%; the corresponding 15N' values amounted to 66.1% and 33.9%, respectively. The sum of the 15N' of the basic amino acids of the blood cells, on an average, amounted to 39.7% of the total cell 15N'; the corresponding average value for the total 15N' in lysine, histidine and arginine of the blood plasma 15N' was 23.6.% and the quota of the three free amino acids of the total NP15N' of the plasma was 6.2%. (author)

  14. Using δ15N of Chironomidae as an index of nitrogen sources and processing within watersheds as part of EPA's National Aquatic Resource Surveys

    Brooks, J. R.; Compton, J.; Herlihy, A.; Sobota, D. J.; Stoddard, J.; Weber, M.

    2014-12-01

    Nitrogen (N) removal in watersheds is an important regulating ecosystem service that can help reduce N pollution in the nation's waterways. However, processes that remove N such as denitrification are generally determined at point locations. Measures that integrate N processing within watersheds and over time would be particularly useful for assessing the degree of this vital service. Because most N removal processes isotopically enrich the N remaining, δ15N from basal food-chain organisms in aquatic ecosystems can provide information on watershed N processing. As part of EPA's National Aquatic Resource Surveys (NARS), we measured δ15N of Chironomidae in lakes, rivers and streams because these larval aquatic insects were found in abundance in almost every lake and stream in the U.S. Using information on nitrogen loading to the watershed, and total N concentrations within the water, we assessed when elevated chironomid δ15N would indicate N removal rather than possible enriched sources of N. Chironomid δ15N values ranged from -4 to +20 ‰, and were higher in rivers and streams than in lakes (median = 7.6 ‰ vs. 4.8 ‰, respectively), indicating that N was processed to a greater degree in lotic chironomids than in lentic ones. For both, δ15N increased with watershed-level agricultural land cover and N loading, and decreased as precipitation increased. In rivers and streams with high synthetic N loading, we found lower N concentrations in streams with higher chironomid δ15N values, suggesting greater N removal. At low levels of synthetic N loading, the pattern reversed, and streams with enriched chironomid δ15N had higher N concentrations, suggesting enriched sources such as manure or sewage. Our results indicate that chironomid δ15N values can provide valuable information about watershed-level N inputs and processing for national water quality monitoring efforts.

  15. δ15N variation in Ulva lactuca as a proxy for anthropogenic nitrogen inputs in coastal areas of Gulf of Gaeta (Mediterranean Sea)

    Highlights: • Ulva lactuca and Cystoseira amentacea δ15N values were assessed in the Gulf of Gaeta. • U. lactuca was more responsive than C. amentacea to environmental pollution. • Comparison of fragments from the same frond overcomes natural isotopic variability. • Spatial analysis indicated areas in the Gulf differently affected by N inputs. - Abstract: We tested the capacity of Ulva lactuca to mark N sources across large marine areas by measuring variation in its δ15N at several sites in the Gulf of Gaeta. Comparisons were made with the macroalga Cystoseira amentacea. Variation of δ15N values was assessed also in the coastal waters off the Circeo Natural Park, where U. lactuca and C. amentacea were harvested, as these waters are barely influenced by human activities and were used as reference site. A small fragment from each frond was preserved before deployment in order to characterize the initial isotopic values. After 48 h of submersion, U. lactuca was more responsive than C. amentacea to environmental variation and δ15N enrichment in the Gulf of Gaeta was observed. The spatial distribution of δ15N enrichment indicated that different macro-areas in the Gulf were affected by N inputs from different origins. Comparison of the δ15N values of fragments taken from the same transplanted frond avoided bias arising from natural isotopic variability

  16. Fate of 15N-urea and 15N-ammonium sulphate applied in different periods to cica-8 rice culture in greenhouse conditions

    The fate of nitrogen fertilizers in rice cultivars (Cica-8) is studied. Urea (1.973% at of 15N) and ammonium sulfate (1.826% at of 15N) are used. The fertilizers are applied in four levels (0,100,200 and 300 Kg N/ha) in shadow coditions and after 30 days of germination. (M.A.C.)

  17. Determination of 15N nitrates in water samples using mass spectrometry

    The nitrogen element (Z = 7) has two stable isotopes, whose relative quantities are 99.64% for 14N and 0.36% for 15N. Nitrogen is part of many processes and reactions that are important to life and that affect the quality of the water. Within the nitrogen cycle there are kinetic and thermodynamic fractionation processes, which are potentially important for tracing its sources and demands. Water contamination due to nitrates is a serious problem that is affecting large parts of the biosphere. Surface water contamination can be remedied by prevention and control measures, but the problem becomes acute when the contamination penetrates to groundwater water. Contaminated groundwater can remain in the aquifers for centuries, even milleniums, and decontamination is very difficult, if not impossible. Isotopic techniques can help to evaluate how vulnerable the groundwater is to contamination from the surface when its displacement speed and extra load area are determined. Then the sources of surface contamination (natural, industrial, agricultural, domestic) can be identified. Isotopic techniques can also describe an incipient contamination, and they can provide an early alert when chemical or biological indicators do not reveal any signs for concern. The isotopic fractionation of several nitrogen compounds provide the basis for using 15N as a hydrological isotope tool. There are three main sources of nitrogen contamination in water, these are: organic nitrogen in the soil, nitrogenized fertilizers, domestic, industrial and animal wastes. The following technical procedure describes the method for determining the isotopic ration 15N/14N in nitrates in water. The nitrate is separated from the water using ion exchange columns through a resin, which is eluded with HCI and with the addition of silver oxide becomes silver nitrate. This solution is freeze-dried and submitted to combustion at 850 in a sealed quartz tube, using copper/copper oxide for the nitrogen reduction and

  18. 15N balance in wheat-moong-soybean cropping sequence

    Field experiments were conducted to study the effect of FYM and S on fertilizer 15N balance in wheat-moong-soybean cropping sequence, with the main emphasis on partial substitution of chemical fertilizer N through FYM. Response to partial substitution of N was observed in the first crop of the sequence. FYM substitution at higher level (50%) resulted in reduction of wheat yield, but 25% substitution of recommended N through FYM increased wheat yield. Total fertilizer N recovery by three crops wheat, moong and soybean grown in sequence ranged between 39 to 55 per cent of which 35 to 41 per cent was utilized by the first crop and 4 to 14 per cent by the second and third crops together while 21 to 36 per cent of the fertilizer N applied to wheat was present in soil after growing three crops. Fertilizer N recovery in soil plant system was 61 to 91 per cent. Higher fertilizer N recovery was associated with higher rate of substitution of FYM for chemical fertilizer. FYM boosted fertilizer N recovery and higher soil retentivity. Sulphur application had no significant effect on per cent residual fertilizer N retention in soil. (author)

  19. Paleobiological Implications of the Isotopic Signatures ( 13C, 15N) of Fossil Mammal Collagen in Scladina Cave (Sclayn, Belgium)

    Bocherens, Hervé; Billiou, Daniel; Patou-Mathis, Marylène; Bonjean, Dominique; Otte, Marcel; Mariotti, André

    1997-11-01

    An isotopic investigation of upper Pleistocene mammal bones and teeth from Scladina cave (Sclayn, Belgium) demonstrated the very good quality of collagen preservation. A preliminary screening of the samples used the amount of nitrogen in whole bone and dentine in order to estimate the preserved amount of collagen before starting the extraction process. The isotopic abundances of fossil specimens from still-extant species are consistent with their trophic position. Moreover, the 15N isotopic abundance is higher in dentine than in bone in bears and hyenas, a phenomenon already observed in modern specimens. These results demonstrate that the isotopic compositions of samples from Scladina cave can be interpreted in ecological terms. Mammoths exhibit a high 15N isotopic abundance relative to other herbivores, as was the case in Siberian and Alaskan samples. These results suggest distinctive dietary adaptations in herbivores living in the mammoth steppe. Cave bears are clearly isotopically different from coeval brown bears, suggesting an ecological separation between species, with a pure vegetarian diet for cave bear and an omnivorous diet for brown bear.

  20. Utilization of 15N-labelled urea in laying hens. 4

    In order to study the utilization of urea in poultry, 3 colostomized laying hybrids were orally supplied with a traditional ration supplemented with 1% 15N'-labelled urea with a 15N excess (15N') of 96.06 atom-% over a period of 6 days. After another 2 days on which the hens received the same ration with unlabelled urea, they were killed. The atom-% 15N' of the blood on an average of the 3 hens was 0.64, of the plasma 1.40 and of the corpuscles 0.47. The TCA-soluble fraction of the blood had an average 15N' of 1.14 atom-%; the 15N amount was 9.7% of the total amount of 15N in the blood. The amount of 15N' in the urea in the blood was 6.8 atom-%. This shows that the absorbed urea is decomposed very slowly. The quota of 15N' in the basic amino acids from the total 15N' of the blood plasma was only 0.3% and that of the corpuscles 2.2%. The average 15N' of the mature follicles was 2.39 atom-% whereas the smallest and the remaining ovary contain 1.12 atom-%. The labelling level of lysine in mature egg cells was, in contrast to this, only 0.08 atom-% 15N' and in infantile follicles 0.04 atom-% 15N'. 1% of the 15N' quota was in the follicles and the remaining ovary. Of the basic amino acids, histidine is most strongly labelled. The lower incorporation of the 15N' from urea into the basic amino acids shows that the nitrogen of this compound can be used for the synthesis of the essential amino acids to a low degree only. (author)

  1. Trophic guilds of generalist feeders in soil animal communities as indicated by stable isotope analysis (15N/14N).

    Oelbermann, K; Scheu, S

    2010-10-01

    We investigated if the commonly used aggregation of organisms into trophic guilds, such as detritivores and predators, in fact represent distinct trophic levels. Soil arthropods of a forest-meadow transect were ascribed a priori to trophic guilds (herbivores, detritivores, predators and necrovores), which are often used as an equivalent to trophic levels. We analysed natural variations in 15N/14N ratios of the animals in order to investigate the trophic similarity of organisms within (a priori defined) trophic guilds. Using trophic guilds as an equivalent to trophic level, the assumed stepwise enrichment of 15N by 3.4 per thousand per trophic level did not apply to detritivores; they were only enriched in 15N by on average 1.5 per thousand compared to litter materials. Predators on average were enriched in 15N by 3.5 per thousand compared to detritivores. Within detritvores and predators delta15N signatures varied markedly, indicating that these trophic guilds are dominated by generalist feeders which form a gradient of organisms feeding on different resources. The results indicate that commonly used trophic guilds, in particular detritivores and predators, do not represent trophic levels but consist of subguilds, i.e. subsets of organisms differing in resource utilization. In particular, in soil and litter food webs where trophic level omnivory is common, the use of distinct trophic levels may be inappropriate. Guilds of species delineated by natural variations of stable isotope ratios are assumed to more adequately represent the structure of litter and soil food webs allowing a more detailed understanding of their functioning. PMID:20109270

  2. The effect of organic matter and nitrification inhibitor on 15 N H4 and 15 N O3 absorption by the maize

    The effect of the forms 15 N H4 and 15 N O3 in presence or absence of organic matter and of the nitrification inhibitor AM (2-amino-4-chloro-6-methyl-pyrimidine) in dry matter weight and nitrogen content of the plant derived from soil and form fertilizer is studied. The experiment was carried out in greenhouse and the test plant was the hybrid Maize Centralmex . The fertilizers (15 N H4)2 S O4 and Na15 N O3, were added in two levels: 40 and 120 Kg N/ha, with 1,02% of N and 1,4% of 15 N in excess, respectively. Three soils of different physical and chemical characteristics were used; Regosol intergrade, Latosol Roxo and Podzolized de Lins e Marilia var. Marilia. (M.A.C.)

  3. 15N isotopic techniques to study nitrogen cycle in soil-plant-atmosphere system

    Intensification of agriculture to meet the increasing food demand has caused severe disruption in natural balance of global as well as regional nitrogen cycle, potentially threatening the future sustainability of agriculture and environment of the total fertilizer nitrogen used in agriculture globally, only less than half is recovered by crop plants, rest is lost to the environment, resulting in several environmental problems such as ground water pollution and global warming, besides huge economic loss of this costly input in agriculture. Improving fertilizer nitrogen use efficiency and minimising N loss to the environment is the key to regain the lost control of nitrogen cycle in agriculture. Fertilizer nitrogen use efficiency depends largely on N requirement of crops, N supply from soil and fertilizer through N transformations in soil, and N losses from the soil-water-plant system. 15N isotopic techniques have the potential to provide accurate measurement quantification of different processes involved in N cycle such as fixation of atmospheric N2, transformations- mineralization and immobilization- of soil and fertilizer N which governs N supply to plants, and N losses to the environment through ammonia volatilization, denitrification and nitrate leaching. 15N tracers can also give precise identification of ways and sources of N loss from agriculture. These information can be used to develop strategies for increasing fertilizer N use efficiency and minimizing the loss of this costly input from agriculture to environment, which in turn will help to achieve the tripartite goal of food security, agricultural profitability and environmental quality. (author)

  4. Stabilization dynamics of root versus needle-derived 13C and 15N during 10 years in a temperate forest soil.

    Bird, J. A.; Hatton, P. J.; Castanha, C.; Torn, M. S.

    2012-12-01

    Belowground plant carbon (C) allocation as fine roots can result in greater retention of C in soils compared with aboveground litter in temperate forest ecosystems. However, much of our understanding of the fate of fine root C and nitrogen (N) in soils comes from short-term studies, often lasting only a few months to a few years. In 2011, we concluded a 10-year field study that compared the fate of dual-labeled (13C/15N) Ponderosa pine fine roots (forest soil of the Sierra Nevada, CA, USA. The 13C- and 15N-labeled fine roots or needles were added to mesocosms at two soil depths (top of O or A horizon) to compare C and N stabilization in mineral versus organic soil horizons. We will present data on retention of litter C and N in soil after 0.5, 1.5, 5 and 10 years in situ. For soil samples recovered after 5 years, litter-derived C and N recovered in the mineral soil was partitioned into several operationally-defined physical and chemical soil organic matter (SOM) fractions, which were also characterized by natural abundance 14C. In addition, we compared two fractionation methods (i.e., with and without occluded light fraction isolation) on the partitioning of litter-derived C and N in mineral soil. After 5 years in situ the retention of fine root C in soil (59.9±3.8%) was significantly greater than that of added needle C (38.4±2.0%); however the depth of litter placement in the soil did not affect total litter C or N recovery. Our results provide a direct, decade-scale measure of stabilization of above- and belowground plant inputs to soil, including a portrait of the dominant stabilization mechanisms.

  5. Analysis of carbon and nitrogen co-metabolism in yeast by ultrahigh-resolution mass spectrometry applying {sup 13}C- and {sup 15}N-labeled substrates simultaneously

    Blank, Lars M. [TU Dortmund University, Laboratory of Chemical Biotechnology, Department of Biochemical and Chemical Engineering, Dortmund (Germany); RWTH Aachen University, Institute of Applied Microbiology - iAMB, Aachen Biology and Biotechnology - ABBt, Aachen (Germany); Desphande, Rahul R. [TU Dortmund University, Laboratory of Chemical Biotechnology, Department of Biochemical and Chemical Engineering, Dortmund (Germany); Michigan State University, Department of Plant Biology, East Lansing, MI (United States); Schmid, Andreas [TU Dortmund University, Laboratory of Chemical Biotechnology, Department of Biochemical and Chemical Engineering, Dortmund (Germany); Hayen, Heiko [Leibniz-Institut fuer Analytische Wissenschaften-ISAS-e.V, Dortmund (Germany); University of Wuppertal, Department of Food Chemistry, Wuppertal (Germany)

    2012-06-15

    Alternative metabolic pathways inside a cell can be deduced using stable isotopically labeled substrates. One prerequisite is accurate measurement of the labeling pattern of targeted metabolites. Experiments are generally limited to the use of single-element isotopes, mainly {sup 13}C. Here, we demonstrate the application of direct infusion nanospray, ultrahigh-resolution Fourier transform ion cyclotron resonance-mass spectrometry (FTICR-MS) for metabolic studies using differently labeled elemental isotopes simultaneously - i.e., {sup 13}C and {sup 15}N - in amino acids of a total protein hydrolysate. The optimized strategy for the analysis of metabolism by a hybrid linear ion trap-FTICR-MS comprises the collection of multiple adjacent selected ion monitoring scans. By limiting both the width of the mass range and the number of ions entering the ICR cell with automated gain control, sensitive measurements of isotopologue distribution were possible without compromising mass accuracy and isotope intensity mapping. The required mass-resolving power of more than 60,000 is only achievable on a routine basis by FTICR and Orbitrap mass spectrometers. Evaluation of the method was carried out by comparison of the experimental data to the natural isotope abundances of selected amino acids and by comparison to GC/MS results obtained from a labeling experiment with {sup 13}C-labeled glucose. The developed method was used to shed light on the complexity of the yeast Saccharomyces cerevisiae carbon-nitrogen co-metabolism by administering both {sup 13}C-labeled glucose and {sup 15}N-labeled alanine. The results indicate that not only glutamate but also alanine acts as an amino donor during alanine and valine synthesis. Metabolic studies using FTICR-MS can exploit new possibilities by the use of multiple-labeled elemental isotopes. (orig.)

  6. Biomonitoring of traffic-related nitrogen oxides in the Maurienne valley (Savoie, France), using purple moor grass growth parameters and leaf 15N/14N ratio

    Effects of traffic-related nitrogenous emissions on purple moor grass (Molinia caerulea (L.) Moench) transplants, used here as a new biomonitoring species, were assessed along 500 m long transects orthogonal to roads located in two open areas in the Maurienne valley (French Alps). Leaves were sampled during summer 2004 and 2005 for total N-content and 15N-abundance determination while nitrogen oxides (NO and NO2) concentrations were determined using passive diffusion samplers. A significant and negative correlation was observed between plant total N-content, and 15N-abundance and the logarithm of the distance to the road axis. The strongest decreases in plant N parameters were observed between 15 and 100 m from road axis. They were equivalent to background levels at a distance of about 800 m from the roads. In addition, motor vehicle pollution significantly affected vegetation at road edge, as was established from the relationship between leaf 15N-abundance, total N-content and road traffic densities. - Effects of motor vehicle emissions on the δ15N, N-contents and growth of purple moor grass as a function of the distance to roads.

  7. Improved diffusion technique for 15N:14N analysis of ammonium and nitrate from aqueous samples by stable isotope spectrometry

    Nitrogen (N) isotope ratio mass spectrometry (IRMS) by Dumas combustion and continuous flow mass spectrometry has become a wide-spread tool for the studies of N turnover. The speed and labor efficiency of 15N determinations from aqueous solutions such as soil solutions or soil extracts are often limited by sample preparation. Several procedures for the conversion of dissolved ammonium (NH4+) or nitrate NO3- to gaseous ammonia and its subsequent trapping in acidified traps have been elaborated in the last decades. They are based on the use of acidified filters kept either above the respective solution or in floating PTFE envelopes. In this paper, we present an improved diffusion method with a fixed PTFE trap. The diffusion containers are continuously kept in a vertical rotary shaker. Quantitative diffusion can thus be achieved in only three days. For solutions with NH4+ levels of only 1 mg N kg-1 and NO3- concentrations of 12 mg N kg-1, recovery rates of 98.8-102% were obtained. By addition of 15N labeled and non-labeled NH4+ and NO3- it was shown that no cross-contamination from NH4+ to NO3- or vice versa takes place even when one form is labeled to more than 1 at %15N while the other form has natural 15N content. The method requires no intermediate step of ammonia volatilization before NO3- conversion

  8. Abiotic and biotic factors associated with the presence of Anopheles arabiensis immatures and their abundance in naturally occurring and man-made aquatic habitats

    Gouagna Louis

    2012-07-01

    Full Text Available Abstract Background Anopheles arabiensis (Diptera: Culicidae is a potential malaria vector commonly present at low altitudes in remote areas in Reunion Island. Little attention has been paid to the environmental conditions driving larval development and abundance patterns in potential habitats. Two field surveys were designed to determine whether factors that discriminate between aquatic habitats with and without An. arabiensis larvae also drive larval abundance, comparatively in man-made and naturally occurring habitats. Methods In an initial preliminary survey, a representative sample of aquatic habitats that would be amenable to an intensive long-term study were selected and divided into positive and negative sites based on the presence or absence of Anopheles arabiensis larvae. Subsequently, a second survey was prompted to gain a better understanding of biotic and abiotic drivers of larval abundance, comparatively in man-made and naturally occurring habitats in the two studied locations. In both surveys, weekly sampling was performed to record mosquito species composition and larval density within individual habitats, as well as in situ biological characteristics and physico-chemical properties. Results Whilst virtually any stagnant water body could be a potential breeding ground for An. arabiensis, habitats occupied by their immatures had different structural and biological characteristics when compared to those where larvae were absent. Larval occurrence seemed to be influenced by flow velocity, macrofauna diversity and predation pressure. Interestingly, the relative abundance of larvae in man-made habitats (average: 0.55 larvae per dip, 95%CI [0.3–0.7] was significantly lower than that recorded in naturally occurring ones (0.74, 95%CI [0.5–0.8]. Such differences may be accounted for in part by varying pressures that could be linked to a specific habitat. Conclusions If the larval ecology of An. arabiensis is in general very complex

  9. The synthesis of barbituric acid and some of its derivatives isotopically labelled with 15N

    Full text: Barbituric acid is the parent compound of a large class of barbiturates that have central nervous system depressant properties, although barbituric acid itself is not pharmacologically active. In recent years, barbituric acid derivatives have been studied as antitumor, anticancer and anti-osteoporosis agents. The aim of this paper is to present the synthesis of barbituric acid-15N, 5,5-diethylbarbituric acid-15N (Veronal-15N) and 5-ethyl-5-phenylbarbituric acid- 15N (Phenobarbitone-15N) . As isotopically labelled material we used urea-15N2, 99 at.% 15N produced at National Institute for Research and Development of Isotopic and Molecular Technologies, Cluj-Napoca, Romania. All compounds were fully characterized by Mass Spectrometry analyses, by FT-IR Spectroscopy and RX Diffraction, and the isotopic label was determined by MS on the molecular compounds. (author)

  10. Patterns of δ13 C and δ15 N in wolverine Gulo gulo tissues from the Brooks Range, Alaska

    Fredrik DALERUM; Anders ANGERBJ(O)RN; Kyran KUNKEL; Brad S.SHULTS

    2009-01-01

    Knowledge of carnivore diets is essential to understand hew carnivore populations respond demographically to variations in prey abundance. Analysis of stable isotopes is a useful complement to traditional methods of analyzing carnivore diets. We used data on δ13 C and δ15 N in wolverine tissues to investigate patterns of seasonal and annual diet variation in a wolverine Gulo gulo population in the western Brooks Range, Alaska, USA. The stable isotope ratios in wolverine tissues generally reflected that of terrestrial carnivores, corroborating previous diet studies on wolverines. We also found variation in δ13 C and δ15 N both between muscle samples collected over several years and between tissues with different assimilation rates, even after correcting for isotopic fractionation. This suggests both annual and seasonal diet variation. Our results indicate that data on δ13 C and δ15 N holds promise for qualitative assessments of wolverine diet changes over time. Such temporal variation may be important indicators of ecological responses to environmental perturbations, and we suggest that more refined studies of stable isotopes may be an important tool when studying temporal change in diets of wolverines and similar carnivores.

  11. Patterns of δ13C and δ15N in wolverine Gulo gulo tissues from the Brooks Range, Alaska

    Fredrik DALERUM

    2009-06-01

    Full Text Available Knowledge of carnivore diets is essential to understand how carnivore populations respond demographically to variations in prey abundance. Analysis of stable isotopes is a useful complement to traditional methods of analyzing carnivore diets. We used data on d13C and d15N in wolverine tissues to investigate patterns of seasonal and annual diet variation in a wolverine Gulo gulo population in the western Brooks Range, Alaska, USA. The stable isotope ratios in wolverine tissues generally reflected that of terrestrial carnivores, corroborating previous diet studies on wolverines. We also found variation in d13C and d15N both between muscle samples collected over several years and between tissues with different assimilation rates, even after correcting for isotopic fractionation. This suggests both annual and seasonal diet variation. Our results indicate that data on d13C and d15N holds promise for qualitative assessments of wolverine diet changes over time. Such temporal variation may be important indicators of ecological responses to environmental perturbations, and we suggest that more refined studies of stable isotopes may be an important tool when studying temporal change in diets of wolverines and similar carnivores [Current Zoology 55(3: 188–192, 2009].

  12. Pion elastic and inelastic scattering from 15N

    Data were obtained on the Clinton P. Anderson Los Alamos Meson Physics Facility Energetic Pion Channel and Spectrometer for elastic and inelastic pion scattering from ground state 15N nuclei. States observed here included those of 0.0, 5.27, 6.32, 7.16, 7.30, 7.57, 8.31, 8.57, 9.15, 9.76, 9.9, 10.7, 11.3, 11.9, 12.5, 12.9, 13.1, 14.1, 14.4, 14.6, 15.0, 16.5, 16.9, 17.2, 17.6, 18.3, 18.7, and 18.9 MeV excitation energies. Angular distributions were obtained for scattering at angles from 25 degree to 90 degree in 5 degree increments with an incident pion energy of 164 MeV. Optical model analyses of the elastic (0 MeV) angular distributions with equal point proton and neutron densities in both momentum and coordinate space formulations accurately predict the data, although the two formulations require different energy shifts to do so. This difference is thought to be a result of the more accurate nonlocal representation of the nuclear potential in the momentum space code. Additional spectra were obtained for scattering at constant momentum transfers of .94 and 1.57 fm-1 in order to generate constant momentum transfer excitation functions. Use of these excitation functions, σ(π+)/σ(π-) ratios, and shell model DWIA calculations allowed identification of several excited states having shell-model-like, single particle-hole, pure spin-flip excitations. Shell model and collective model DWIA calculations, as well as the q = .94 and 1.57 fm-1 excitation functions and the σ(π+)/σ(π-) ratios indicate that the other states are generally well represented by a shell model description with collective enhancements

  13. Studies with 15N-labelled lysine in colostomized laying hens. 5

    3 colostomized laying hens received, together with a commercial ration of 120 g, 0.2 % 15N-labelled L-lysine with an atom-% 15N excess (15N') of 48 %; subsequently the same ration was fed over a period od 4 days with 0.2 % unlabelled L-lysine. After the end of the experiment the hens were slaughtered. The atom-% 15N' was determined in total, in the lysine, histidine and arginine N of blood cells, plasma, NPN fraction of the blood, stomach, small intestine, cecum and rectum. 15N' in the blood cells was 0.11 atom-% in the blood plasma 0.17 atom-%, in the NPN fraction of the blood 0.09 atom-%, in the tissues of the gastrointestinal tract 0.11 atom-% and in its contents 0.12 atom-%. On the average the blood contained per hen 77.9 % lysine-15N', 16.4 % arginine-15N' and 5.7 % histidine-15N' of the basic amino acid-15N'. For the gastrointestinal tract 78.7 % lysine-15N', 19.0 % arginine-15N' and 2.3 % histidine-15N' of the 15N' of the basic amino acids were ascertained. In comparison to histidine the α-amino-N of lysine is incorporated to a considerably higher degree into arginine. For lysine and arginine the atom-% 15N' in the contents of the gastrointestinal tract is 4 days after the end of the supplementation of labelled lysine 8 to 10 times higher than in the feces of the last day of the experiment. This indicates a considerable secretion of the 2 amino acids in the gastrointestinal tract and their reabsorption to a large extent. (author)

  14. Soil organic matter stability in agricultural land: New insights using δ15N, δ13C and C:N ratio

    Mao, Yanling; Heiling, Maria; De Clercq, Tim; Resch, Christian; Aigner, Martina; Mayr, Leo; Vanlauwe, Bernard; Thuita, Moses; Steier, Peter; Leifeld, Jens; Merckx, Roel; Spiegel, Heide; Cepuder, Peter; Nguyen, Minh-Long; Zaman, Mohammad; Dercon, Gerd

    2014-05-01

    Soil organic matter (SOM) contains three times more carbon than in the atmosphere or terrestrial vegetation. This major pool of organic carbon is sensitive to climate change, but the mechanisms for carbon stabilization in soils are still not well understood and the ultimate potential for carbon stabilization is unknown. For predicting SOM dynamics, it is necessary to gain information on the turnover rates or stability of different soil organic carbon pools. The common method to determine stability and age of SOM is the 14C radio carbon technique, which is very expensive and therefore limited in use. Conen et al. (2008) developed a model to estimate the SOM stability based on the isotopic discrimination of 15N natural abundance by soil micro-organisms, and the decreasing C:N ratio during organic matter decomposition. This model has been developed for permanent grasslands in the Swiss Alps under steady-state conditions. The objective of our study was to validate whether this model could be used or adapted, in combination with 13C isotope signatures of SOM, to predict the relative age and stability of SOM fractions in more disturbed agricultural ecosystems. The present study was carried out on soils collected from six long-term experimental trials (from 12 to 50 years) under different agricultural management practices (e.g. no tillage vs conventional tillage, and mulch, fertilizer, green or animal manure application), located in Austria, Belgium, Kenya and China. Top and subsoil were sampled until 80-100 cm depth. Particulate organic matter (POM) fraction was obtained by wet sieving (> 63μm) after sonification and density separation (model and preliminary validated by 14C dating. At all sites, the POM has a higher C:N ratio and a lower δ15N signature compared to the mOM fraction. The POM in top soil layers (model, developed for grasslands, can be used to determine the stability of SOM in agricultural ecosystems. The C:N ratio and δ15N signature of the POM and m

  15. The effects of oxides of carbon and nitrogen emissions on the isotope and element abundances in foliage of C3 plants

    The carbon and nitrogen stable isotope abundance of C3 plants mango (Magnifera indica L), molave (Vitex parviflora Juss), talisay (Terminalia catappa L.) leaves harvested from sites with ambient air conditions and sites receiving air pollution contributions from coal-fired power plants were determined and compared. Isotope Ratio Mass Spectroscopy, IRMS was used to determine 13C and 15N in the samples. The elemental composition of the samples was determined using Inductively Coupled Plasma-Atomic Emission Spectrometry, ICP-AES. The 13C of the leaves grown in ambient air were found to fall within the range of -25.0 to -22.0 per mill and a close agreement with the literature values for the natural abundance of 13C in C3 plants (-27.0 to -21.0 per mill). The 13C abundance of plants obtained from sites polluted by coal-fired plants were sporadic from -35 to 24.0 per mille. The 15N abundance in leaves grown under ambient air condition (-1.0 to 2.0 per mille) were way below the 15N abundance of plants from coal-fired plant-polluted regions (16.0 to 17.5 per mille). Elemental exposition indicated no differences in element concentrations in leaves from ambient and polluted sites. Differences exist in the Ca, Mg, K ratios across species and are affected by seasonal variation. (author)

  16. Seasonal variation in species composition and abundance of demersal fish and invertebrates in a Seagrass Natural Reserve on the eastern coast of the Shandong Peninsula, China

    Xu, Qiang; Guo, Dong; Zhang, Peidong; Zhang, Xiumei; Li, Wentao; Wu, Zhongxin

    2016-03-01

    Seagrass habitats are structurally complex ecosystems, which support high productivity and biodiversity. In temperate systems the density of seagrass may change seasonally, and this may influence the associated fish and invertebrate community. Little is known about the role of seagrass beds as possible nursery areas for fish and invertebrates in China. To study the functioning of a seagrass habitat in northern China, demersal fish and invertebrates were collected monthly using traps, from February 2009 to January 2010. The density, leaf length and biomass of the dominant seagrass Zostera marina and water temperature were also measured. The study was conducted in a Seagrass Natural Reserve (SNR) on the eastern coast of the Shandong Peninsula, China. A total of 22 fish species and five invertebrate species were recorded over the year. The dominant fish species were Synechogobius ommaturus, Sebastes schlegelii, Pholis fangi, Pagrus major and Hexagrammos otakii and these species accounted for 87% of the total number of fish. The dominant invertebrate species were Charybdis japonica and Octopus variabilis and these accounted for 98% of the total abundance of invertebrates. There was high temporal variation in species composition and abundance. The peak number of fish species occurred in August-October 2009, while the number of individual fish and biomass was highest during November 2009. Invertebrate numbers and biomass was highest in March, April, July and September 2009. Temporal changes in species abundance of fishes and invertebrates corresponded with changes in the shoot density and leaf length of the seagrass, Zostera marina.

  17. 15N tracer kinetic studies on the validity of various 15N tracer substances for determining whole-body protein parameters in very small preterm infants

    Reliable 15N tracer substances for tracer kinetic determination of whole-body protein parameters in very small preterm infants are still a matter of intensive research, especially after some doubts have been raised about the validity of [15N]glycine, a commonly used 15N tracer. Protein turnover, synthesis, breakdown, and further protein metabolism data were determined by a paired comparison in four preterm infants. Their post-conceptual age was 32.2 +/- 0.8 weeks, and their body weight was 1670 +/- 181 g. Tracer substances applied in this study were a [15N]amino acid mixture (Ia) and [15N]glycine (Ib). In a second group of three infants with a post conceptual age of 15N-labeled 32.0 +/- 1.0 weeks and a body weight of 1,907 +/- 137 g, yeast protein hydrolysate (II) was used as a tracer substance. A three-pool model was employed for the analysis of the data. This model takes into account renal and fecal 15N losses after a single 15N pulse. Protein turnovers were as follows: 11.9 +/- 3.1 g kg-1 d-1 (Ia), 16.2 +/- 2.5 g kg-1 d-1 (Ib), and 10.8 +/- 3.0 g kg-1 d-1 (II). We were able to demonstrate an overestimation of the protein turnover when Ib was used. There was an expected correspondence in the results obtained from Ia and II. The 15N-labeled yeast protein hydrolysate is a relatively cheap tracer that allows reliable determination of whole-body protein parameters in very small preterm infants

  18. House and Stable Fly Seasonal Abundance, Larval Development Substrates, and Natural Parasitism on Small Equine Farms in Florida.

    Machtinger, E T; Leppla, N C; Hogsette, J A

    2016-08-01

    House flies, Musca domestica Linnaeus, and stable flies, Stomoxys calcitrans (L.) (Diptera: Muscidae), are common pests on horse farms. The successful use of pupal parasitoids for management of these pests requires knowledge of seasonal fluctuations and biology of the flies as well as natural parasitism levels. However, these dynamics have not been investigated on small equine farms. A 1-year field study began in July 2010, in north central Florida, to determine adult fly population levels and breeding areas on four small equine farms. Weekly surveillance showed that pest flies were present year-round, though there were differences in adult population levels among farms and seasons. Fly development was not confirmed on two of the four small farms, suggesting that subtle differences in husbandry may adversely affect the development of immature flies. In six substrates previously identified as the most common among the farms, stable fly puparia were found overwhelmingly in hay mixed with equine manure and house fly puparia were found in fresh pine shavings mixed with equine manure. Natural parasitism was minimal as expected, but greatest numbers of natural parasitoids collected were of the genus Spalangia. Differences in adult and immature fly numbers recovered emphasizes the need for farm owners to confirm on-site fly development prior to purchase and release of biological control agents. Additionally, due to the low natural parasitism levels and domination of parasitism by Spalangia cameroni, augmentative releases using this species may be the most effective. PMID:26902468

  19. Use of 15N Label in Organic Synthesis and Spectroscopy. Part I: Preparation of 15N-Labeled tert-Butylamine

    Talaty, Erach R.; Boese, Christopher A.; Adewale, Sanni M.; Ismail, Mohammed S.; Provenzano, Frank A.; Utz, Melissa J.

    2002-02-01

    The preparation of 15N-labeled tert-butylamine involves the conversion of the correspondingly labeled potassium cyanide into the 15N-labeled tert-butylformamide via the Ritter reaction in 85% yield, followed by hydrolysis with either aqueous sodium hydroxide or hydrochloric acid. The NMR spectra of the compounds provide a valuable opportunity for discussing several important topics in NMR spectroscopy, such as cis-trans isomerism due to restricted rotation and 15N coupling. Comparison of the IR spectra of the labeled and unlabeled compounds permits a forum for discussing the theory of vibrational frequencies.

  20. Measurement of {sup 15}N relaxation in deuterated amide groups in proteins using direct nitrogen detection

    Vasos, Paul R.; Hall, Jennifer B. [University of Maryland, Department of Chemistry and Biochemistry, Center for Biomolecular Structure and Organization (United States); Kuemmerle, Rainer [Bruker Biospin AG, NMR Division (Switzerland); Fushman, David [University of Maryland, Department of Chemistry and Biochemistry, Center for Biomolecular Structure and Organization (United States)], E-mail: fushman@umd.edu

    2006-09-15

    {sup 15}N chemical shielding tensors contain useful structural information, and their knowledge is essential for accurate analysis of protein backbone dynamics. The anisotropic component (CSA) of {sup 15}N chemical shielding can be obtained from {sup 15}N relaxation measurements in solution. However, the predominant contribution to nitrogen relaxation from {sup 15}N-{sup 1}H dipolar coupling in amide groups limits the sensitivity of these measurements to the actual CSA values. Here we present nitrogen-detected NMR experiments for measuring {sup 15}N relaxation in deuterated amide groups in proteins, where the dipolar contribution to {sup 15}N relaxation is significantly reduced by the deuteration. Under these conditions nitrogen spin relaxation becomes a sensitive probe for variations in {sup 15}N chemical shielding tensors. Using the nitrogen direct-detection experiments we measured the rates of longitudinal and transverse {sup 15}N relaxation for backbone amides in protein G in D{sub 2}O at 11.7 T. The measured relaxation rates are validated by comparing the overall rotational diffusion tensor obtained from these data with that from the conventional {sup 15}N relaxation measurements in H{sub 2}O. This analysis revealed a 17-24{sup o} angle between the NH-bond and the unique axis of the {sup 15}N chemical shielding tensor.

  1. Measurement of 15N relaxation in deuterated amide groups in proteins using direct nitrogen detection

    15N chemical shielding tensors contain useful structural information, and their knowledge is essential for accurate analysis of protein backbone dynamics. The anisotropic component (CSA) of 15N chemical shielding can be obtained from 15N relaxation measurements in solution. However, the predominant contribution to nitrogen relaxation from 15N-1H dipolar coupling in amide groups limits the sensitivity of these measurements to the actual CSA values. Here we present nitrogen-detected NMR experiments for measuring 15N relaxation in deuterated amide groups in proteins, where the dipolar contribution to 15N relaxation is significantly reduced by the deuteration. Under these conditions nitrogen spin relaxation becomes a sensitive probe for variations in 15N chemical shielding tensors. Using the nitrogen direct-detection experiments we measured the rates of longitudinal and transverse 15N relaxation for backbone amides in protein G in D2O at 11.7 T. The measured relaxation rates are validated by comparing the overall rotational diffusion tensor obtained from these data with that from the conventional 15N relaxation measurements in H2O. This analysis revealed a 17-24o angle between the NH-bond and the unique axis of the 15N chemical shielding tensor

  2. Fields of application and results of analytic procedures with 15N in pediatric alimentary research

    Investigation of protein metabolism in nutritional pediatric research by means of 15N tracer techniques has been relatively seldom used up to now. 15N labelled compounds for these purposes are not injurious to health. The technique is based on oral or intravenous application of the tracer substances and on 15N analysis of the urine fractions. The subsequent calculation of protein synthesis and breakdown rate, turnover and reutilisation of amino acids from protein breakdown as well as the size of the metabolic pool offers detailed information of protein metabolism. Determination of these parameters was performed in infants on mother's milk and formula feeding and on chemically defined diet. As an example of utilisation of D-amino acids for protein synthesis the 15N-D-phenylalanin retention on parenteral nutrition was found to be 33% of the applied dosis at an average. An oral 15N glycine loading test proved to be of value for the prediction of the therapeutic effect of human growth hormon in numerous types of dwarfism. Further application of 15N tracer technique dealt with utilisation of 15N urea for bacterial protein synthesis of the intestinal flora and with incorporation of 15N from 15N glycine and 15N lysine into the jejunal mucosa for measuring the enterocyte regeneration. (author)

  3. Studies with 15N-labelled lysine in colostomized hens. 3

    In a metabolism experiment with 15N-labelled lysine 3 colostomized laying hybrids received over 4 days 0.2% L-lysine with 48 at% 15N excess (15N') in addition to a ration conventionally produced and, subsequent to this, unlabelled lysine for four days. At the end of the experiment the hens were killed and the individual organs and tissues were prepared for 15N analysis. The incorporation of the lysine-15N' into the further amino acids of follicles, ovary and oviduct is described. The at% 15N' of the complete range of amino acids was analyzed in the individual follicles. Various levels of heavy nitrogen could be detected in all essential and non-essential amino acids. Of the total amount of 15N' detected in the follicles 64.0%, 65.0% and 61.2%, resp., could be detected in lysine and 25.2%, 25.4% and 28.7%, resp., in the other amino acids (hens 1 to 3). In the ovary on average 61.6% and in the oviduct 54.2% of the respective 15N' amount was detected in lysine. In the ovary 10.9% and in the oviduct 8.4% 15N' of the total 15N' of these samples were incorporated into the arginine molecules. (author)

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

    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.

  5. Passage and absorption of dietary and endogenous nitrogen in different regions of the digestive tract of rats given a single meal of 15N-labelled barley

    Young male Wistar rats (86.9 +- 0.96 g) were fasted for 24 hours and then offered a single meal (intake of 1 to 2.5 g) of 15N-labelled barley (5.34 atom% 15N excess). The test meal also contained Cr2O3 (20 mg/g). Groups of five animals were killed 0.5; 1; 1.5; 2; 2.5; 4; 6 and 8 hours after removal of food. The contents of different regions of the digestive tract (stomach, proximal, middle and distal third of small intestine, large intestine) and feces were analyzed for Cr2O3 and for N and 15N abundance in both a TCA soluble and a TCA precipitable fraction. The distribution patterns of Cr2O3 and 15N along the digestive tract were very similar. If the disappearance of 15N from the contents of the small and of the large intestines was expressed as a proportion of the gastric outflow of 15N, a disappearance rate of 90% was found. On the basis of isotopic dilution the proportion of dietary nitrogen in digesta was calculated. The results illustrated the intensive dilution of dietary nitrogen by endogenous secretions in all regions of the digestive tract. In the distal small intestine endogenous nitrogen accounted for 70% of total nitrogen. 17 mg endogenous N were produced by the stomach within 8 hours after the single meal. The results show the value of the method in determining the true digestibility of nitrogen in 15N-labelled feedstuffs more accurately than with classical methods and in providing an insight into the dynamics of nitrogen absorption and secretion in the digestive tract. (author)

  6. Deuterium transfer in the bioconversion of glucose to ethanol studied by specific isotope labeling at the natural abundance level

    Martin, G.J.; Zhang, B.L.; Naulet, N.; Martin, M.L.

    1986-08-20

    Site-specific natural isotope fractionation measured by deuterium NMR (SNIF-NMR) was used for investigating the deuterium transfers occurring in the fermentation of sugars into ethanol. In contrast to carbon-13, which is usually assumed to be randomly distributed within the glucose skeleton, very large deviations with respect to a statistical repartition are determined for deuterium. By transforming glucose samples from different origins into acetates and nitrates, the absolute values of the D/H ratios in the nonexchangeable sites were obtained. The hydroxyl sites were considered to contribute to the isotope content of the starting water medium. No direct connection is found between glucose and the methylene site which is only sensitive, with a strong discriminating effect against deuterium, to the isotope content of water. A redistribution coefficient slightly less than unity (0.96 for a concentration of sugar of 100 g L/sup -1/) is found between the isotope ratio of the end and starting water media. The site-specific natural isotope parameters of ethanol constitute a faithful and powerful probe for investigating the physiological biochemical and climatological effects which have governed the photosynthesis of sugars in natural conditions.

  7. Deuterium transfer in the bioconversion of glucose to ethanol studied by specific isotope labeling at the natural abundance level

    Site-specific natural isotope fractionation measured by deuterium NMR (SNIF-NMR) was used for investigating the deuterium transfers occurring in the fermentation of sugars into ethanol. In contrast to carbon-13, which is usually assumed to be randomly distributed within the glucose skeleton, very large deviations with respect to a statistical repartition are determined for deuterium. By transforming glucose samples from different origins into acetates and nitrates, the absolute values of the D/H ratios in the nonexchangeable sites were obtained. The hydroxyl sites were considered to contribute to the isotope content of the starting water medium. No direct connection is found between glucose and the methylene site which is only sensitive, with a strong discriminating effect against deuterium, to the isotope content of water. A redistribution coefficient slightly less than unity (0.96 for a concentration of sugar of 100 g L-1) is found between the isotope ratio of the end and starting water media. The site-specific natural isotope parameters of ethanol constitute a faithful and powerful probe for investigating the physiological biochemical and climatological effects which have governed the photosynthesis of sugars in natural conditions

  8. Sensitivity enhancement in natural-abundance solid-state 33S MAS NMR spectroscopy employing adiabatic inversion pulses to the satellite transitions

    Hansen, Michael Ryan; Brorson, Michael; Bildsøe, Henrik; Skibsted, Jørgen; Jakobsen, Hans J.

    2008-02-01

    The WURST (wideband uniform rate smooth truncation) and hyperbolic secant (HS) pulse elements have each been employed as pairs of inversion pulses to induce population transfer (PT) between the four energy levels in natural abundance solid-state 33S (spin I = 3/2) MAS NMR, thereby leading to a significant gain in intensity for the central transition (CT). The pair of inversion pulses are applied to the satellite transitions for a series of inorganic sulfates, the sulfate ions in the two cementitious materials ettringite and thaumasite, and the two tetrathiometallates (NH 4) 2WS 4 and (NH 4) 2MoS 4. These materials all exhibit 33S quadrupole coupling constants ( CQ) in the range 0.1-1.0 MHz, with precise CQ values being determined from analysis of the PT enhanced 33S MAS NMR spectra. The enhancement factors for the WURST and HS elements are quite similar and are all in the range 1.74-2.25 for the studied samples, in excellent agreement with earlier reports on HS enhancement factors (1.6-2.4) observed for other spin I = 3/2 nuclei with similar CQ values (0.3-1.2 MHz). Thus, a time saving in instrument time by a factor up to five has been achieved in natural abundance 33S MAS NMR, a time saving which is extremely welcome for this important low-γ nucleus.

  9. Dynamic nuclear polarization NMR enables the analysis of Sn-Beta zeolite prepared with natural abundance ¹¹⁹Sn precursors.

    Gunther, William R; Michaelis, Vladimir K; Caporini, Marc A; Griffin, Robert G; Román-Leshkov, Yuriy

    2014-04-30

    The catalytic activity of tin-containing zeolites, such as Sn-Beta, is critically dependent on the successful incorporation of the tin metal center into the zeolite framework. However, synchrotron-based techniques or solid-state nuclear magnetic resonance (ssNMR) of samples enriched with (119)Sn isotopes are the only reliable methods to verify framework incorporation. This work demonstrates, for the first time, the use of dynamic nuclear polarization (DNP) NMR for characterizing zeolites containing ~2 wt % of natural abundance Sn without the need for (119)Sn isotopic enrichment. The biradicals TOTAPOL, bTbK, bCTbK, and SPIROPOL functioned effectively as polarizing sources, and the solvent enabled proper transfer of spin polarization from the radical's unpaired electrons to the target nuclei. Using bCTbK led to an enhancement (ε) of 75, allowing the characterization of natural-abundance (119)Sn-Beta with excellent signal-to-noise ratios in <24 h. Without DNP, no (119)Sn resonances were detected after 10 days of continuous analysis. PMID:24697321

  10. Utilization of 15N-labelled urea in laying hens. 7

    3 colostomized laying hybrids received 1% 15N-labelled urea with 96.06 atom-% 15N excess (15N') with a commercial ration over a period of 6 days. After the application of the same ration with unlabelled urea on the following 2 days the animals were butchered. In the muscles of breast, legs and heart, the labelling of total nitrogen and the incorporation of urea 15N' into 15 amino acids of the 3 different kinds of muscles were ascertained. On average, significant differences could be ascertained between the atom-% 15N of the muscles was 0.25 and 0.34 atom-%, resp.; that of the cardial proteins 0.71 atom-% 15N'. The incorporation of urea 15N into the basic amino acids is low and varies both between the kinds of muscles and between the amino acids. On average the highest level of labelling was found among the essential amino acids valine, isoleucine and leucine; the average atom-% 15N' for the muscles of the breast is 0.13, of the leg 0.17, and of the heart 0.27; the 15N' quota of branched Chain amino acids in the total 15N' of the respective muscle is accordingly 6.0%, 5.0% and 4.5%. The non-essential amino acids, particularly glutamic acid, are more highly labelled in the muscles than the essential ones. A 15N' for glutamic acid of 0.24 atom-% in the breast muscles, of 0.27 atom-% in those of the legs and of 0.64 atom-% in the heart muscle could be detected. The average quota of the 15N' of these acid amino acids in the 15N' for breast, leg and heart muscles is 7.4, 6.2 and 6.7, resp. The quota of the 15N' in the 6 non-essential amino acids in the total 15N' in all 3 kinds of muscles is approximately two thirds and in the 9 essential ones one third of the total 15N'. Although the results show that there is a certain incorporation of 15N' from urea into the amino acids of the muscle proteins, their contribution to meeting the demands is irrelevant. (author)