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Sample records for stable autotrophic nitrogen

  1. Oxygen-Nitrogen Relationships in Autotrophic Nitrification

    PubMed Central

    Wezernak, C. T.; Gannon, J. J.

    1967-01-01

    Oxygen utilization by the autotrophic nitrifiers Nitrosomonas and Nitrobacter was studied. Experimental evidence is presented which reflects the effect of carbon dioxide fixation on overall oxygen utilization in autotrophic nitrification. Measurement of dissolved oxygen and inorganic nitrogen changes indicates that oxygen-nitrogen ratios in inorganic nitrogen oxidation are equal to 3.22 parts (expressed in milligrams per liter) of oxygen per part of ammonia nitrogen oxidized to nitrite nitrogen and 1.11 parts of oxygen per part of nitrite nitrogen oxidized to nitrate nitrogen. These values rather than the stoichiometric ratios should be used in nitrogenous oxygen demand calculations. PMID:6077417

  2. Autotrophic nitrogen removal in one lab-scale vertical submerged biofilm reactor

    NASA Astrophysics Data System (ADS)

    Liang, Zhiwei; Chen, Yingxu; Li, Wenhong; Yang, Shangyuan; Du, Ping

    In this study, the process performance of a new vertical submerged biofilm reactor for complete autotrophic ammonia removal was investigated using synthetic wastewater. The main objectives of this study were to evaluate the flexibility of the reactor, achieve partial autotrophic nitrification with influent ammonium nitrogen ranging from 40 to 280 mg L -1, and achieve a stable half partial autotrophic nitrification by controlling hydraulic retention time (HRT) and alkalinity. A very low concentration of nitrate was observed in the effluent during nitrification. Then autotrophic denitrification revealed Anammox bacteria were present and active in the central anaerobic parts of the bioreactor which was inoculated with a mixed microbial consortium from activated sludge. The results of this study demonstrated that autotrophic denitrification processes can coexist with heterotrophic denitrifying processes in the same environment even if Anammox bacteria were less competitive than heterotrophic denitrifying bacteria.

  3. Identification of the autotrophic denitrifying community in nitrate removal reactors by DNA-stable isotope probing.

    PubMed

    Xing, Wei; Li, Jinlong; Cong, Yuan; Gao, Wei; Jia, Zhongjun; Li, Desheng

    2017-04-01

    Autotrophic denitrification has attracted increasing attention for wastewater with insufficient organic carbon sources. Nevertheless, in situ identification of autotrophic denitrifying communities in reactors remains challenging. Here, a process combining micro-electrolysis and autotrophic denitrification with high nitrate removal efficiency was presented. Two batch reactors were fed organic-free nitrate influent, with H(13)CO3(-) and H(12)CO3(-) as inorganic carbon sources. DNA-based stable-isotope probing (DNA-SIP) was used to obtain molecular evidence for autotrophic denitrifying communities. The results showed that the nirS gene was strongly labeled by H(13)CO3(-), demonstrating that the inorganic carbon source was assimilated by autotrophic denitrifiers. High-throughput sequencing and clone library analysis identified Thiobacillus-like bacteria as the most dominant autotrophic denitrifiers. However, 88% of nirS genes cloned from the (13)C-labeled "heavy" DNA fraction showed low similarity with all culturable denitrifiers. These findings provided functional and taxonomical identification of autotrophic denitrifying communities, facilitating application of autotrophic denitrification process for wastewater treatment.

  4. Simultaneous energy recovery and autotrophic nitrogen removal from sewage at moderately low temperatures.

    PubMed

    Gao, Da-Wen; Lu, Jian-Cong; Liang, Hong

    2014-03-01

    This study assessed the technical feasibility of treating sewage with a combination of direct anaerobic treatment and autotrophic nitrogen removal, while simultaneously achieving energy recovery and nitrogen removal under moderately low temperatures. The concentrations of ammonia, nitrite, and COD in effluent were below 1, 0.1, and 30 mg/L, respectively. In the up-flow, anaerobic sludge fixed-bed, there was no obvious change observed in the total methane production at temperatures of 35 ± 1 °C, 28 ± 1 °C, 24 ± 3 °C, and 17 ± 3 °C, with the accumulation of volatile fatty acids occurring with decreasing temperatures. The control strategy employed in this study achieved a stable effluent with equimolar concentrations of nitrite and ammonium, coupled with high nitrite accumulation (>97 %) in the partial nitrification sequencing batch reactor system at moderately low temperatures. In the anaerobic ammonium oxidation (anammox) reactor, a short hydraulic retention time of 0.96 h, with a nitrogen removal rate of 0.83 kgN/(m(3)/day) was achieved at 12-15 °C. At low temperatures, the corresponding fluorescence in situ hybridization image revealed a high amount of anammox bacteria. This study demonstrates that efficient nitrogen removal and energy recovery from sewage at moderately low temperatures can be achieved by utilizing a combined system. Additionally, this system has the potential to become energy-neutral or even energy-producing.

  5. Tracking heterotrophic and autotrophic carbon cycling by magnetotactic bacteria in freshwater sediments using DNA stable isotope probing

    NASA Astrophysics Data System (ADS)

    Kürşat Coşkun, Ömer; Roud, Sophie; He, Kuang; Petersen, Nikolai; Gilder, Stuart; Orsi, William D.

    2017-04-01

    Magnetotactic bacteria (MTB) are diverse, widespread, motile prokaryotes which biomineralize nanosize magnetic minerals, either magnetite or gregite, under highly conserved genetic control and have magnetotaxis to align their position in aquatic environment according to Earth's magnetic field. They play important roles on some geobiological cycle of important minerals such as iron, sulphur, nitrogen and carbon. Yet, to date, their importance in carbon cycle and carbon source in their natural environment have not been previously studied. In this study, we focused on freshwater benthic carbon cycling of MTB and total bacteria using DNA stable isotope probing (DNA-SIP) technique coupled with quantitative PCR (qPCR). Pond sediments from Unterlippach (Germany) were amended with 13C-labelled sodium bicarbonate and 13C-labelled organic matter, and incubated in the dark over a two week time period. Applying separate qPCR assays specific for total bacteria and MTB, respectively, allowed us to estimate the contribution of MTB to total heterotrophic and autotrophic carbon cycling via DNA-SIP. After one week, there was a slight degree of autotrophic activity which increased markedly after two weeks. Comparing total DNA to the qPCR data revealed that changes in the buoyant density of DNA was due mainly to autotrophic bacterial production. DNA-SIP also identified heterotrophic utilization of 13C-labelled organic matter by MTB after 1 week. The qPCR data also allowed us to estimate uptake rates based on the incubation times for heterotrophic and autotrophic MTB. High-throughput DNA sequencing of 16S rRNA genes showed that most of the MTB involved in carbon cycling were related to the Magnetococcus genus. This study sheds light on the carbon sources for MTB in a natural environment and helps unravel their ecological role in the carbon cycle.

  6. [Oxygen-limited autotrophic nitrification and denitrification--a novel technology for biological nitrogen removal].

    PubMed

    Zhang, Dan; Xu, Hui; Li, Xiangli; Zhang, Ying; Chen, Guanxiong

    2003-12-01

    Oxygen-limited autotrophic nitrification and denitrification (OLAND) is a biological nitrogen removal process coupled with partial nitrification and anaerobic ammonium oxidation. In our study, the nitrification was blocked at nitrite stage by controlling the dissolved oxygen concentration at 0.1-0.3 mg.L-1, and then, the denitrification proceeded, with the residual ammonium at the partial nitrification stage as electron donor. As a completely autotrophic nitrification-denitrification process, the OLAND was of many advantages (e.g., low energy consumption, high nitrogen removal rate and small footprint of system), and suitable in particular for treating low COD/NH4(+)-N ratio wastewater. It has become one of the most prosperous and practicable biological nitrogen removal technologies. The recent research of OLAND was reviewed, and its microbial mechanism as well as its applicable prospect was remarked in this paper.

  7. Detection of autotrophic verrucomicrobial methanotrophs in a geothermal environment using stable isotope probing.

    PubMed

    Sharp, Christine E; Stott, Matthew B; Dunfield, Peter F

    2012-01-01

    Genomic analysis of the methanotrophic verrucomicrobium "Methylacidiphilum infernorum" strain V4 has shown that most pathways conferring its methanotrophic lifestyle are similar to those found in proteobacterial methanotrophs. However, due to the large sequence divergence of its methane monooxygenase-encoding genes (pmo), "universal" pmoA polymerase chain reaction (PCR) primers do not target these bacteria. Unlike proteobacterial methanotrophs, "Methylacidiphilum" fixes carbon autotrophically, and uses methane only for energy generation. As a result, techniques used to detect methanotrophs in the environment such as (13)CH(4)-stable isotope probing (SIP) and pmoA-targeted PCR do not detect verrucomicrobial methanotrophs, and they may have been overlooked in previous environmental studies. We developed a modified SIP technique to identify active methanotrophic Verrucomicrobia in the environment by labeling with (13)CO(2) and (13)CH(4), individually and in combination. Testing the protocol in "M. infernorum" strain V4 resulted in assimilation of (13)CO(2) but not (13)CH(4), verifying its autotrophic lifestyle. To specifically detect methanotrophs (as opposed to other autotrophs) via (13)CO(2)-SIP, a quantitative PCR (qPCR) assay specific for verrucomicrobial-pmoA genes was developed and used in combination with SIP. Incubation of an acidic, high-temperature geothermal soil with (13)CH(4) + (12)CO(2) caused little shift in the density distribution of verrucomicrobial-pmoA genes relative to controls. However, labeling with (13)CO(2) in combination with (12)CH(4) or (13)CH(4) induced a strong shift in the distribution of verrucomicrobial-pmoA genes towards the heavy DNA fractions. The modified SIP technique demonstrated that the primary methanotrophs active in the soil were autotrophs and belonged to the Verrucomicrobia. This is the first demonstration of autotrophic, non-proteobacterial methanotrophy in situ, and provides a tool to detect verrucomicrobial methanotrophs

  8. Detection of autotrophic verrucomicrobial methanotrophs in a geothermal environment using stable isotope probing

    PubMed Central

    Sharp, Christine E.; Stott, Matthew B.; Dunfield, Peter F.

    2012-01-01

    Genomic analysis of the methanotrophic verrucomicrobium “Methylacidiphilum infernorum” strain V4 has shown that most pathways conferring its methanotrophic lifestyle are similar to those found in proteobacterial methanotrophs. However, due to the large sequence divergence of its methane monooxygenase-encoding genes (pmo), “universal” pmoA polymerase chain reaction (PCR) primers do not target these bacteria. Unlike proteobacterial methanotrophs, “Methylacidiphilum” fixes carbon autotrophically, and uses methane only for energy generation. As a result, techniques used to detect methanotrophs in the environment such as 13CH4-stable isotope probing (SIP) and pmoA-targeted PCR do not detect verrucomicrobial methanotrophs, and they may have been overlooked in previous environmental studies. We developed a modified SIP technique to identify active methanotrophic Verrucomicrobia in the environment by labeling with 13CO2 and 13CH4, individually and in combination. Testing the protocol in “M. infernorum” strain V4 resulted in assimilation of 13CO2 but not 13CH4, verifying its autotrophic lifestyle. To specifically detect methanotrophs (as opposed to other autotrophs) via 13CO2-SIP, a quantitative PCR (qPCR) assay specific for verrucomicrobial-pmoA genes was developed and used in combination with SIP. Incubation of an acidic, high-temperature geothermal soil with 13CH4 + 12CO2 caused little shift in the density distribution of verrucomicrobial-pmoA genes relative to controls. However, labeling with 13CO2 in combination with 12CH4 or 13CH4 induced a strong shift in the distribution of verrucomicrobial-pmoA genes towards the heavy DNA fractions. The modified SIP technique demonstrated that the primary methanotrophs active in the soil were autotrophs and belonged to the Verrucomicrobia. This is the first demonstration of autotrophic, non-proteobacterial methanotrophy in situ, and provides a tool to detect verrucomicrobial methanotrophs in other ecosystems. PMID

  9. Biochemical characteristic along UBAF in a one-stage autotrophic nitrogen removal reactor.

    PubMed

    Liu, Tao; Li, Dong; Zhang, Jie

    2016-12-01

    The Up-flow biological aerated filter (UBAF) based on a one-stage autotrophic nitrogen removal process has been widely investigated nowadays. In this work, the biochemical characteristic along the volcanic-filled UBAF reactor had been studied. The results indicate that short-rod, spherical and elliptical (averaged 0.2-1.0 μm) microorganisms with a specific irregular cauliflower profile existed in the system. Species identification showed Nitrosococcus- and Nitrosomonas-related aerobic ammonium-oxidizing bacteria (AerAOB) and Candidatus Kuenenia stuttgartiensis-like anaerobic ammonium-oxidizing bacteria (AnAOB) were the predominant functional bacteria that mixed with each other and showed no distinct niche in the system. However, the bioactivity of functional microorganisms displayed differently at different filter layers, with a better pollutant-removal activity in the lower parts than in the upper parts of the UBAF. In the lower parts, compact and small zooglea formed, whereas it trended to be larger and looser along the filter. Moreover, there was better biodiversity of AerAOB in the lower part, while AnAOB showed stable and low biodiversity along the filter.

  10. Biodegradation of tetramethylammonium hydroxide (TMAH) in completely autotrophic nitrogen removal over nitrite (CANON) process.

    PubMed

    Chen, Shen-Yi; Lu, Li-An; Lin, Jih-Gaw

    2016-06-01

    This study conducted a completely autotrophic nitrogen removal over nitrite (CANON) process in a continuous anoxic upflow bioreactor to treat synthetic wastewater with TMAH (tetramethylammonium hydroxide) ranging from 200 to 1000mg/L. The intermediates were analyzed for understanding the metabolic pathway of TMAH biodegradation in CANON process. In addition, (15)N-labeled TMAH was used as the substrate in a batch anoxic bioreactor to confirm that TMAH was converted to nitrogen gas in CANON process. The results indicated that TMAH was almost completely biodegraded in CANON system at different influent TMAH concentrations of 200, 500, and 1000mg/L. The average removal efficiencies of total nitrogen were higher than 90% during the experiments. Trimethylamine (TMA) and methylamine (MA) were found to be the main biodegradation intermediates of TMAH in CANON process. The production of nitrogen gas with (15)N-labeled during the batch anaerobic bioreactor indicated that CANON process successfully converted TMAH into nitrogen gas.

  11. The feasibility of using a two-stage autotrophic nitrogen removal process to treat sewage.

    PubMed

    Ma, Bin; Zhang, Shujun; Zhang, Liang; Yi, Peng; Wang, Junmin; Wang, Shuying; Peng, Yongzhen

    2011-09-01

    The feasibility of using a two-stage autotrophic nitrogen removal process to treat sewage was examined in this study. The obtained results showed that total nitrogen (TN) could be efficiently removed by 88.38% when influent TN and chemical oxygen demand (COD) were 45.87 and 44.40 mg/L, respectively. In the first stage, nitritation was instantly achieved by the bioaugmentation strategy, and can be maintained under limited oxygen condition (below 0.2mg/L). The ratio of nitrite to ammonium in the effluent of the nitritation reactor can be controlled at approximate 1.0 by adjusting aeration rate. In the second stage, anammox was realized in the upflow anaerobic sludge blanket (UASB) reactor, where the total nitrogen removal rate was 0.40 kg Nm(-3)d(-1) under limited-substrate condition. Therefore, the organic matter in sewage can be firstly concentrated in biomass which could generate biogas (energy). Then, nitrogen in sewage could be removed in a two-stage autotrophic nitrogen removal process.

  12. Autotrophic nitrogen removal from low strength waste water at low temperature.

    PubMed

    Hendrickx, Tim L G; Wang, Yang; Kampman, Christel; Zeeman, Grietje; Temmink, Hardy; Buisman, Cees J N

    2012-05-01

    Direct anaerobic treatment of municipal waste waters allows for energy recovery in the form of biogas. A further decrease in the energy requirement for waste water treatment can be achieved by removing the ammonium in the anaerobic effluent with an autotrophic process, such as anammox. Until now, anammox has mainly been used for treating warm (>30 °C) and concentrated (>500 mg N/L) waste streams. Application in the water line of municipal waste water treatment poses the challenges of a lower nitrogen concentration (<100 mg N/L) and a lower temperature (≤ 20 °C). Good biomass retention and a short HRT are required to achieve a sufficiently high nitrogen loading rate. For this purpose a 4.5 L gaslift reactor was inoculated with a small amount of anammox granules and operated for 253 days at 20 °C. The synthetic influent contained (69 ± 5) mg (NH(4)(+) + NO(2)(-))/L and 20 vol.% of anaerobically stabilised effluent. Results showed a clear increase in nitrogen loading rate (NLR) up to 0.31 g (NH(4) + NO(2))-N/(L × d) at a hydraulic retention time (HRT) of 5.3 h. A low effluent concentration of 0.03-0.17 mg (NH(4)(+)+NO(2)(-))-N/L could be achieved. Anammox biomass was retained as granules and as a biofilm on the reactor walls, which contributed 54 and 46%, respectively, towards total activity. The biomass was further characterised by an estimated net growth rate of 0.040 d(-1) and an apparent activation energy of 72 kJ/mol. The results presented in this paper showed that anammox bacteria can be applied for autotrophic nitrogen removal from the water line at a municipal waste water treatment plant. Combining direct anaerobic treatment with autotrophic nitrogen removal opens opportunities for energy-efficient treatment of municipal waste waters. Copyright © 2012 Elsevier Ltd. All rights reserved.

  13. Autotrophic nitrogen removal in sequencing batch biofilm reactors at different oxygen supply modes.

    PubMed

    Wantawin, C; Juateea, J; Noophan, P L; Munakata-Marr, J

    2008-01-01

    Conventional nitrification-denitrification treatment is a common way to treat nitrogen in wastewater, but this process is costly for low COD/N wastewaters due to the addition of air and external carbon-source. However, ammonia may alternatively be converted to dinitrogen gas by autotrophic bacteria utilizing aerobically autotrophically produced nitrite as an electron acceptor under anoxic conditions. Lab-scale sequencing batch biofilm reactors (SBBRs) inoculated with normal nitrifying sludge were employed to study the potential of an oxygen-limited autotrophic nitrification-denitrification process initiated with typical nitrifying sludge for treating a synthetic ammonia wastewater devoid of organic carbon in one step. The ring-laced fibrous carrier (length 0.32 m, surface area 3.4 m2/m) was fixed vertically in a 3 L reactor. Two different air supply modes were applied:continuous aeration to control dissolved oxygen at 1.5 mg/L and intermittent aeration. High nitrogen removals of more than 50% were obtained in both SBBRs. At an ammonia loading of 0.882 gm N/m2-day [hydraulic retention time (HRT) of 24 hr], the SBBR continuously aerated to 1.5 mg DO/L had slightly higher nitrogen removal (64%) than the intermittently alternated SBBR (55%). The main form of residual nitrogen in the effluent was ammonia, at concentrations of 25 mg/L and 37 mg N/L in continuous and intermittent aeration SBBRs, respectively. Ammonia was completely consumed when ammonia loading was reduced to 0.441 gm N/m2-day [HRT extended to 48 hr]. The competitive use of nitrite by aerobic nitrite oxidizing bacteria (ANOB) with anaerobic ammonia-oxidizing bacteria (anammox bacteria) during the expanded aeration period under low remaining ammonia concentration resulted in higher nitrate production and lower nitrogen loss in the continuous aeration SBBR than in the intermittent aeration SBBR. The nitrogen removal efficiencies in SBBRs with continuous and alternating aerated were 80% and 86% respectively

  14. Analysis of nitrification in agricultural soil and improvement of nitrogen circulation with autotrophic ammonia-oxidizing bacteria.

    PubMed

    Matsuno, Toshihide; Horii, Sachie; Sato, Takanobu; Matsumiya, Yoshiki; Kubo, Motoki

    2013-02-01

    Accumulations of inorganic nitrogen (NH₄⁺, NO₂⁻, and NO₃⁻) were analyzed to evaluate the nitrogen circulation activity in 76 agricultural soils. Accumulation of NH₄⁺ was observed, and the reaction of NH₄⁺→ NO₂⁻ appeared to be slower than that of NO₂⁻ → NO₃⁻ in agricultural soil. Two autotrophic and five heterotrophic ammonia-oxidizing bacteria (AOB) were isolated and identified from the soils, and the ammonia-oxidizing activities of the autotrophic AOB were 1.0 × 10³-1.0 × 10⁶ times higher than those of heterotrophic AOB. The relationship between AOB number, soil bacterial number, and ammonia-oxidizing activity was investigated with 30 agricultural soils. The ratio of autotrophic AOB number was 0.00032-0.26% of the total soil bacterial number. The soil samples rich in autotrophic AOB (>1.0 × 10⁴ cells/g soil) had a high nitrogen circulation activity, and additionally, the nitrogen circulation in the agricultural soil was improved by controlling the autotrophic AOBs.

  15. Autotrophic and heterotrophic denitrification for simultaneous removal of nitrogen, sulfur and organic matter.

    PubMed

    Guerrero, Lorna; Aguirre, Juan P; Muñoz, Maria A; Barahona, Andrea; Huiliñir, Cesar; Montalvo, Silvio; Borja, Rafael

    2016-07-02

    The aim of this investigation was to assess the startup and operation of a laboratory-scale hybrid UASB-Anaerobic Filter Reactor (UASFB) of 1 L volume, kept at 30°C, in order to carry out a simultaneous autotrophic and heterotrophic denitrification process. First, the heterotrophic and autotrophic populations were separately enriched, with specific cultures and subsequently the UASFB was inoculated with 2 g L(-1) of volatile suspended solids (VSS), with a ratio of 1.5:1 (autotrophs: heterotrophs). The influent or synthetic wastewater used was composed of: Na2S2O3·5H2O, CH3COOK, NaNO3, NaHCO3, K2HPO4, NH4Cl and saline solution. The concentrations varied depending on the organic loading rate (OLR), nitrogen loading rate (NLR) and sulfur loading rate (SLR) applied. In the UASFB reactor, two experimental conditions were tested and assessed: (i) COD/N ratio of 3.6 and SLR of 0.75 kg S m(-3) d(-1); and (ii) COD/N ratio of 5.8 and SLR of 0.25 kg S m(-3) d(-1). The results obtained demonstrated that an inoculum coming from an anaerobic reactor was able to carry out the process, obtaining a maximum nitrate removal of 85.3% in the first stage of operation and 99.5% in the second stage. The recovery of sulfur in form of sulfate in the effluent did not present a tendency to stabilize during the measured time, with a maximum thiosulfate removal of 32.5%, when the SLR was lowered to 0.25 kg S m(-3) d(-1). The maximum organic matter elimination, measured as COD, was 75.8%, which indicates the relatively good performance and behavior of the heterotrophic microorganisms.

  16. Nitrogen, carbon, and sulfur isotopic change during heterotrophic (Pseudomonas aureofaciens) and autotrophic (Thiobacillus denitrificans) denitrification reactions

    NASA Astrophysics Data System (ADS)

    Hosono, Takahiro; Alvarez, Kelly; Lin, In-Tian; Shimada, Jun

    2015-12-01

    In batch culture experiments, we examined the isotopic change of nitrogen in nitrate (δ15NNO3), carbon in dissolved inorganic carbon (δ13CDIC), and sulfur in sulfate (δ34SSO4) during heterotrophic and autotrophic denitrification of two bacterial strains (Pseudomonas aureofaciens and Thiobacillus denitrificans). Heterotrophic denitrification (HD) experiments were conducted with trisodium citrate as electron donor, and autotrophic denitrification (AD) experiments were carried out with iron disulfide (FeS2) as electron donor. For heterotrophic denitrification experiments, a complete nitrate reduction was accomplished, however bacterial denitrification with T. denitrificans is a slow process in which, after seventy days nitrate was reduced to 40% of the initial concentration by denitrification. In the HD experiment, systematic change of δ13CDIC (from - 7.7‰ to - 12.2‰) with increase of DIC was observed during denitrification (enrichment factor εN was - 4.7‰), suggesting the contribution of C of trisodium citrate (δ13C = - 12.4‰). No SO42 - and δ34SSO4 changes were observed. In the AD experiment, clear fractionation of δ13CDIC during DIC consumption (εC = - 7.8‰) and δ34SSO4 during sulfur use of FeS2-S (around 2‰), were confirmed through denitrification (εN = - 12.5‰). Different pattern in isotopic change between HD and AD obtained on laboratory-scale are useful to recognize the type of denitrification occurring in the field.

  17. Nitrogen, carbon, and sulfur isotopic change during heterotrophic (Pseudomonas aureofaciens) and autotrophic (Thiobacillus denitrificans) denitrification reactions.

    PubMed

    Hosono, Takahiro; Alvarez, Kelly; Lin, In-Tian; Shimada, Jun

    2015-12-01

    In batch culture experiments, we examined the isotopic change of nitrogen in nitrate (δ(15)NNO3), carbon in dissolved inorganic carbon (δ(13)CDIC), and sulfur in sulfate (δ(34)SSO4) during heterotrophic and autotrophic denitrification of two bacterial strains (Pseudomonas aureofaciens and Thiobacillus denitrificans). Heterotrophic denitrification (HD) experiments were conducted with trisodium citrate as electron donor, and autotrophic denitrification (AD) experiments were carried out with iron disulfide (FeS2) as electron donor. For heterotrophic denitrification experiments, a complete nitrate reduction was accomplished, however bacterial denitrification with T. denitrificans is a slow process in which, after seventy days nitrate was reduced to 40% of the initial concentration by denitrification. In the HD experiment, systematic change of δ(13)CDIC (from -7.7‰ to -12.2‰) with increase of DIC was observed during denitrification (enrichment factor εN was -4.7‰), suggesting the contribution of C of trisodium citrate (δ(13)C=-12.4‰). No SO4(2-) and δ(34)SSO4 changes were observed. In the AD experiment, clear fractionation of δ(13)CDIC during DIC consumption (εC=-7.8‰) and δ(34)SSO4 during sulfur use of FeS2-S (around 2‰), were confirmed through denitrification (εN=-12.5‰). Different pattern in isotopic change between HD and AD obtained on laboratory-scale are useful to recognize the type of denitrification occurring in the field.

  18. Effects of HRT and water temperature on nitrogen removal in autotrophic gravel filter.

    PubMed

    Xu, Jing-hang; He, Sheng-bing; Wu, Su-qing; Huang, Jung-Chen; Zhou, Wei-li; Chen, Xue-chu

    2016-03-01

    Organic Carbon added to low ratio of carbon to nitrogen (C/N ratio) wastewater to enhance heterotrophic denitrification performance might lead to higher operating costs and secondary pollution. In this study, sodium thiosulfate (Na2S2O3) was applied as an electron donor for a gravel filter (one kind of constructed wetland) to investigate effects of hydraulic retention time (HRT) and water temperature on the nitrate removal efficiency. The results show that with an HRT of 12 h, the average total nitrogen (TN) removal efficiencies were 91% at 15-20 °C and 18% at 3-6 °C, respectively. When HRT increased to 24 h, the average TN removal increased accordingly to 41% at 3-6 °C, suggesting denitrification performance was improved by extended HRT at low water temperatures. Due to denitrification, 96% of added nitrate nitrogen (NO3(-)-N) was converted to nitrogen gas, with a mean flux of nitrous oxide (N2O) was 0.0268-0.1500 ug m(-2) h(-1), while 98.86% of thiosulfate was gradually converted to sulfate throughout the system. Thus, our results show that the sulfur driven autotrophic denitrification constructed wetland demonstrated an excellent removal efficiency of nitrate for wastewater treatment. The HRT and water temperature proved to be two influencing factors in this constructed wetland treatment system.

  19. Autotrophic nitrogen removal over nitrite in a sponge-bed trickling filter.

    PubMed

    Sánchez Guillén, J A; Jayawardana, L K M C B; Lopez Vazquez, C M; de Oliveira Cruz, L M; Brdjanovic, D; van Lier, J B

    2015-01-01

    Partial nitritation in sponge-bed trickling filters (STF) under natural air circulation was studied in two reactors: STF-1 and STF-2 operated at 30°C with sponge thickness of 0.75 and 1.50cm, respectively. The coexistence of nitrifiers and Anammox bacteria was obtained and attributed to the favorable environment created by the reactors' design and operational regimes. After 114days of operation, the STF-1 had an average NH4(+)-N removal of 69.3% (1.17kgN/m(3)sponged) and a total nitrogen removal of 52.2% (0.88kgN/m(3)sponged) at a Nitrogen Loading Rate (NLR) of 1.68kgN/m(3)sponged and Hydraulic Retention Time (HRT) of 1.71h. The STF-2 showed an average NH4(+)-N removal of 81.6 % (0.77kgN/m(3)sponged) and a total nitrogen removal of 54% (0.51kgN/m(3)sponged), at an NLR of 0.95kgN/m(3)sponged and HRT of 2.96h. The findings suggest that autotrophic nitrogen removal over nitrite in STF systems is a feasible alternative. Copyright © 2015 Elsevier Ltd. All rights reserved.

  20. The effect of SRT on nitrate formation during autotrophic nitrogen removal of anaerobically treated wastewater.

    PubMed

    Lee, Po-Heng; Kwak, Wonji; Bae, Jeaho; McCarty, Perry L

    2013-01-01

    Autotrophic nitrogen removal, coupling nitritation (ammonium to nitrite) with anaerobic ammonium oxidation (anammox), offers a promising nitrogen-removal alternative, especially for post-treatment of anaerobically-treated wastewater. However, previous reports suggest that less than 90% total nitrogen removal should be expected with this process alone because over 10% of the ammonium removed will be converted to nitrate. This is caused because nitrite conversion to nitrate is required for reduction of carbon dioxide to cell carbon. However, recent research results suggest that more limited nitrate formation of only a few per cent sometimes occurs. It was hypothesized such lower nitrate yields may result from use of long solids retention times (SRT) where net biological yields are low, and providing that the ratio of oxygen added to influent ammonium concentrations is maintained at or below 0.75 mol/mol. Overall reaction equations were developed for each process and combined to evaluate the potential effect of SRT on process stoichiometry. The results support the use of a long SRT to reduce net cell yield, which in turn results in a small percentage conversion to nitrate during ammonium removal and high total nitrogen removals in the range of 90 to 94%.

  1. Sequentially aerated membrane biofilm reactors for autotrophic nitrogen removal: microbial community composition and dynamics

    PubMed Central

    Pellicer-Nàcher, Carles; Franck, Stéphanie; Gülay, Arda; Ruscalleda, Maël; Terada, Akihiko; Al-Soud, Waleed Abu; Hansen, Martin Asser; Sørensen, Søren J; Smets, Barth F

    2014-01-01

    Membrane-aerated biofilm reactors performing autotrophic nitrogen removal can be successfully applied to treat concentrated nitrogen streams. However, their process performance is seriously hampered by the growth of nitrite oxidizing bacteria (NOB). In this work we document how sequential aeration can bring the rapid and long-term suppression of NOB and the onset of the activity of anaerobic ammonium oxidizing bacteria (AnAOB). Real-time quantitative polymerase chain reaction analyses confirmed that such shift in performance was mirrored by a change in population densities, with a very drastic reduction of the NOB Nitrospira and Nitrobacter and a 10-fold increase in AnAOB numbers. The study of biofilm sections with relevant 16S rRNA fluorescent probes revealed strongly stratified biofilm structures fostering aerobic ammonium oxidizing bacteria (AOB) in biofilm areas close to the membrane surface (rich in oxygen) and AnAOB in regions neighbouring the liquid phase. Both communities were separated by a transition region potentially populated by denitrifying heterotrophic bacteria. AOB and AnAOB bacterial groups were more abundant and diverse than NOB, and dominated by the r-strategists Nitrosomonas europaea and Ca. Brocadia anammoxidans, respectively. Taken together, the present work presents tools to better engineer, monitor and control the microbial communities that support robust, sustainable and efficient nitrogen removal. PMID:24112350

  2. Efficient single-stage autotrophic nitrogen removal with dilute wastewater through oxygen supply control.

    PubMed

    Kwak, Wonji; McCarty, Perry L; Bae, Jaeho; Huang, Yu-Tzu; Lee, Po-Heng

    2012-11-01

    Autotrophic nitrogen removal via ammonia oxidizing (AOB) and anaerobic ammonium oxidizing (anammox) bacteria was evaluated for treatment of a dilute 50mg/L ammonia-containing solution in a single-stage nitrogen-removal filter at 25°C. Important was an external oxygenation system that permitted close control and measurement of oxygen supply, a difficulty with the generally used diffused air systems. Hydraulic retention time (HRT) was reduced in steps from 15 to 1h. At 1h HRT, total nitrogen (TN) removals varied between 73% and 94%, the maximum being obtained with a benchmark oxygenation ratio of 0.75mol O(2)/mol ammonia fed. At higher ratios, nitrate was formed causing TN removal efficiency to decrease. With lower ratios, TN and ammonia removals decreased in proportion to the decrease in BOR. When operating at or below the BOR, nitrate formation equaled no more than 2% of the ammonia removed, a value much less than has previously been reported. Copyright © 2012 Elsevier Ltd. All rights reserved.

  3. Coupling autotrophic denitrification with partial nitritation-anammox (PNA) for efficient total inorganic nitrogen removal.

    PubMed

    Dasgupta, Sunayna; Wu, Sha; Goel, Ramesh

    2017-06-27

    The performance of and the microbial ecology in an integrated lab scale set up comprising of a PN/A bioreactor and an elemental sulfur-supported packed bed autotrophic denitrification (ESSAD) are reported. The PN/A reactor exhibited an average removal rate of 0.56±0.103kgNm(-3)d(-1), whereas the ESSAD reactor removed an average of 0.0018kg NO3(-)-Nm(-3)d(-1). The combined average removal rate was 0.6kgNm(-3)d(-1), yielding an overall total inorganic nitrogen efficiency of 97%. Based on 16S rRNA gene clone libraries from the ESSAD reactor, the extracted Operational Taxonomic Units (OTUs) formed a clade with Thiobacillus denitrificans sp. indicating a common ancestral relationship. High throughput amplicon sequencing targeting V3 region of 16S rRNA gene for the biofilm in the ESSAD also revealed an abundance of the Thiobacillus genus. Additionally, 16s rRNA amplicon sequencing of the genomic DNA from the PN/A reactor reflected a dominance of the Planctomycetes phylum. Copyright © 2017 Elsevier Ltd. All rights reserved.

  4. Separating Autotrophic and Heterotrophic Contributions to Soil Respiration in Maize-Based Agroecosystems Using Stable Carbon Isotope Ratio Mass Spectrometry.

    NASA Astrophysics Data System (ADS)

    Amos, B.; Walters, D. T.; Madhavan, S.; Arkebauer, T. J.; Scoby, D. L.

    2005-12-01

    Any effort to establish a carbon budget for a growing crop by means of a thorough accounting of all C sources and sinks will require the ability to discriminate between autotrophic and heterotrophic contributions to soil surface CO2 flux. Autotrophic soil respiration (Ra) is defined as combined root respiration and the respiration of soil microorganisms residing in the rhizosphere and using root-derived carbohydrates as an energy source, while heterotrophic respiration (Rh) is defined as the respiration of soil microorganisms and macroorganisms not directly under the influence of the live root system and using SOM as an energy source. We partition soil surface CO2 flux into its autotrophic and heterotrophic components by combining root exclusion with stable carbon isotope techniques in production scale (~65 ha) maize-based agroecosystems. After flux measurements, small chambers are placed on collars in both root excluded shields and in non-root excluded soil, ambient headspace CO2 is removed using a soda lime trap, and soil-respired C is allowed to collect in the chambers. Soil respiration samples are then collected in 12mL evacuated exetainers and analyzed for δ13C by means of a Finnigan Delta-S isotope ratio mass spectrometer interfaced with a Thermo Finnigan GasBench II and a cryogenic trap to increase CO2 concentration. These δ13C measurements were made throughout the 2005 growing season in maize fields representing three agroecosystems: irrigated continuous maize, irrigated maize-soybean rotation, and rainfed maize soybean rotation. Estimates of autotrophic and heterotrophic soil respiration along with other results of this study will be presented.

  5. Autotrophic nitrogen removal from ammonium at low applied voltage in a single-compartment microbial electrolysis cell.

    PubMed

    Zhan, Guoqiang; Zhang, Lixia; Li, Daping; Su, Wentao; Tao, Yong; Qian, Junwei

    2012-07-01

    A new approach was developed to achieve autotrophic nitrogen removal from ammonium at low applied voltage in a single-compartment 3-dimensional microbial electrolysis cell (MEC). The MEC consisted of anodic and cathodic electrodes, on which nitrifying and denitrifying biofilms, respectively, were attached. Nitrogen removal can be enhanced at an applied voltage in the MEC. Besides, the nitrogen removal efficiency gradually increased from 70.3% to 92.6% with the increase of applied voltage from 0.2 to 0.4V, as well as the maximum current was varied from 4.4 to 14 mA. The corresponding coulombic efficiency also increased from 82% to 94.4%, indicating that the increasing applied voltage could enhance electron extraction from ammonium during its oxidative removal. The DO was found to be a critical factor which affected the nitrogen removal in this MEC system. These results demonstrated that the MEC process was applicable to achieve autotrophic nitrogen removal from wastewater containing ammonium.

  6. Implementing a Nitrogen-Based Model for Autotrophic Respiration Using Satellite and Field Observations

    NASA Technical Reports Server (NTRS)

    Choudhury, Bhaskar J.; Houser, Paul (Technical Monitor)

    2001-01-01

    The rate of carbon accumulation by terrestrial plant communities in a process-level, mechanistic modeling is the difference of the rate of gross photosynthesis by a canopy (A(sub g)) and autotrophic respiration (R) of the stand. Observations for different biomes often show that R to be a large and variable fraction of A(sub g), ca. 35% to 75%, although other studies suggest the ratio of R and A(sub g) to be less variable. Here, R has been calculated according to the two compartment model as being the sum of maintenance and growth components. The maintenance respiration of foliage and living fine roots for different biomes has been determined objectively from observed nitrogen content of these organs. The sapwood maintenance respiration is based on pipe theory, and checked against an independently derived equation considering sapwood biomass and its maintenance coefficient. The growth respiration has been calculated from the difference of A(sub g) and maintenance respiration. The A(sub g) is obtained as the product of biome-specific radiation use efficiency for gross photosynthesis under unstressed conditions and intercepted photosynthetically active radiation, and adjusted for stress. Calculations have been done using satellite and ground observations for 36 consecutive months (1987-1989) over large contiguous areas (ca. 10(exp 5) sq km) of boreal forests, crop land, temperate deciduous forest, temperate grassland, tropical deciduous forest, tropical evergreen forest, tropical savanna, and tundra. The ratio of annual respiration and gross photosynthesis, (R/A(sub g)), is found to be 0.5-0.6 for temperate and cold adopted biome areas, but somewhat higher for tropical biome areas (0.6-0.7). Interannual variation of the fluxes is found to be generally less than 15%. Calculated fluxes are compared with observations and several previous estimates. Results of sensitivity analysis are presented for uncertainties in parameterization and input data. It is found that

  7. 454-Pyrosequencing Analysis of Bacterial Communities from Autotrophic Nitrogen Removal Bioreactors Utilizing Universal Primers: Effect of Annealing Temperature.

    PubMed

    Gonzalez-Martinez, Alejandro; Rodriguez-Sanchez, Alejandro; Rodelas, Belén; Abbas, Ben A; Martinez-Toledo, Maria Victoria; van Loosdrecht, Mark C M; Osorio, F; Gonzalez-Lopez, Jesus

    2015-01-01

    Identification of anaerobic ammonium oxidizing (anammox) bacteria by molecular tools aimed at the evaluation of bacterial diversity in autotrophic nitrogen removal systems is limited by the difficulty to design universal primers for the Bacteria domain able to amplify the anammox 16S rRNA genes. A metagenomic analysis (pyrosequencing) of total bacterial diversity including anammox population in five autotrophic nitrogen removal technologies, two bench-scale models (MBR and Low Temperature CANON) and three full-scale bioreactors (anammox, CANON, and DEMON), was successfully carried out by optimization of primer selection and PCR conditions (annealing temperature). The universal primer 530F was identified as the best candidate for total bacteria and anammox bacteria diversity coverage. Salt-adjusted optimum annealing temperature of primer 530F was calculated (47°C) and hence a range of annealing temperatures of 44-49°C was tested. Pyrosequencing data showed that annealing temperature of 45°C yielded the best results in terms of species richness and diversity for all bioreactors analyzed.

  8. 454-Pyrosequencing Analysis of Bacterial Communities from Autotrophic Nitrogen Removal Bioreactors Utilizing Universal Primers: Effect of Annealing Temperature

    PubMed Central

    Rodriguez-Sanchez, Alejandro; Rodelas, Belén; Abbas, Ben A.; Martinez-Toledo, Maria Victoria; van Loosdrecht, Mark C. M.; Osorio, F.; Gonzalez-Lopez, Jesus

    2015-01-01

    Identification of anaerobic ammonium oxidizing (anammox) bacteria by molecular tools aimed at the evaluation of bacterial diversity in autotrophic nitrogen removal systems is limited by the difficulty to design universal primers for the Bacteria domain able to amplify the anammox 16S rRNA genes. A metagenomic analysis (pyrosequencing) of total bacterial diversity including anammox population in five autotrophic nitrogen removal technologies, two bench-scale models (MBR and Low Temperature CANON) and three full-scale bioreactors (anammox, CANON, and DEMON), was successfully carried out by optimization of primer selection and PCR conditions (annealing temperature). The universal primer 530F was identified as the best candidate for total bacteria and anammox bacteria diversity coverage. Salt-adjusted optimum annealing temperature of primer 530F was calculated (47°C) and hence a range of annealing temperatures of 44–49°C was tested. Pyrosequencing data showed that annealing temperature of 45°C yielded the best results in terms of species richness and diversity for all bioreactors analyzed. PMID:26421306

  9. Autotrophic nitrogen removal process in a potable water treatment biofilter that simultaneously removes Mn and NH4(+)-N.

    PubMed

    Cai, Yan'an; Li, Dong; Liang, Yuhai; Zeng, Huiping; Zhang, Jie

    2014-11-01

    Ammonia (NH4(+)-N) removal pathways were investigated in a potable water treatment biofilter that simultaneously removes manganese (Mn) and NH4(+)-N. The results indicated a significant loss of nitrogen in the biofilter. Both the completely autotrophic nitrogen removal over nitrite (CANON) process and nitrification were more likely to contribute to NH4(+)-N removal. Moreover, the model calculation results demonstrated that the CANON process contributed significantly to the removal of NH4(+)-N. For influent NH4(+)-N levels of 1.030 and 1.749mg/L, the CANON process contribution was about 48.5% and 46.6%, respectively. The most important finding was that anaerobic ammonia oxidation (ANAMMOX) bacteria were detectable in the biofilter. It is interesting that the CANON process was effective even for such low NH4(+)-N concentrations. Copyright © 2014 Elsevier Ltd. All rights reserved.

  10. Autotrophic nitrogen removal by a two-step SBR process applied to mixed agro-digestate.

    PubMed

    Scaglione, D; Ficara, E; Corbellini, V; Tornotti, G; Teli, A; Canziani, R; Malpei, F

    2015-01-01

    The aim of this research was to evaluate the applicability of partial-nitritation/anammox processes for biological N removal from a centrifuge supernatant coming from a full scale anaerobic digester fed on a mixture of piggery manure, poultry manure, and agro-wastes. Stable partial nitritation was achieved at pilot-scale (650L SBR), obtaining a suitable influent for the anammox lab-scale SBR reactor (3L). The anammox lab scale reactor was fed with increasing fractions of the partial nitritation effluent, blended with synthetic wastewater. In the last 100days no dilution was used. The nitrogen loading rate applied to the anammox reactor was 0.5-0.6gNL(-)(1)d(-)(1) and the average nitrogen removal was 91±10%. During the first days of operation with undiluted supernatant, the maximum anammox activity in the SBR decreased, but recovered afterwards, suggesting the ability of the anammox biomass to acclimate to the wastewater. N2O emissions in both reactors were also measured. Copyright © 2014 Elsevier Ltd. All rights reserved.

  11. Effects of organic carbon source, chemical oxygen demand/N ratio and temperature on autotrophic nitrogen removal.

    PubMed

    Sánchez Guillén, J A; Yimman, Y; Lopez Vazquez, C M; Brdjanovic, D; van Lier, J B

    2014-01-01

    To assess the feasibility of the Anammox process as a cost-effective post-treatment step for anaerobic sewage treatment, the simultaneous effects of organic carbon source, chemical oxygen demand (COD)/N ratio, and temperature on autotrophic nitrogen removal was studied. In batch experiments, three operating conditions were evaluated at 14, 22 and 30 °C, and at COD/N ratios of 2 and 6. For each operating condition, containing 32 ± 2 mg NH4(+)-N/L and 25 ± 2 mg NO2(-)-N/L, three different substrate combinations were tested to simulate the presence of readily biodegradable and slowly biodegradable organic matter (RBCOD and SBCOD, respectively): (i) acetate (RBCOD); (ii) starch (SBCOD); and (iii) acetate + starch. The observed stoichiometric NO2(-)-N/NH4(+)-N conversion ratios were in the range of 1.19-1.43, and the single or simultaneous presence of acetate and starch did not affect the Anammox metabolism. High Anammox nitrogen removal was observed at 22 °C (77-84%) and 30 °C (73-79%), whereas there was no nitrogen removal at 14 °C; the Anammox activity was strongly influenced by temperature, in spite of the COD source and COD/N ratios applied. These results suggest that the Anammox process could be applied as a nitrogen removal post-treatment for anaerobic sewage systems in warm climates.

  12. Autotrophic nitrogen removal from domestic sewage in MBR-CANON system and the biodiversity of functional microbes.

    PubMed

    Zhang, Xiaojing; Li, Dong; Liang, Yuhai; He, Yongping; Zhang, Yulong; Zhang, Jie

    2013-12-01

    The feasibility of completely autotrophic nitrogen removal over nitrite (CANON) process for treating domestic sewage was investigated in membrane bioreactor (MBR), for which conventional activated sludge was seeded at ambient temperature. By gradually decreasing hydraulic retention time under the oxygen-limited condition, CANON was successfully started-up for 78 days. Finally the MBR-CANON system was adopted for treating domestic sewage, nitrogen and COD removal achieved to 0.97 kg m(-3) d(-1), 80%, respectively, with the effluent turbidity below 1.0 NTU. DGGE profiles showed a distinct community shift of the functional bacteria after seeded to the reactor, and phylogenetic results indicated the predominance of Nitrosomonas and Candidatus Kuenenia stuttgartiensis for nitrogen removal in the reactor. FISH results showed the predominance of aerobic ammonia oxidizing bacteria (AerAOB) and anaerobic ammonia oxidizing bacteria (AnAOB) in the system, both of whose proportion reduced when treated domestic sewage. Copyright © 2013 Elsevier Ltd. All rights reserved.

  13. High efficiency of inorganic nitrogen removal by integrating biofilm-electrode with constructed wetland: Autotrophic denitrifying bacteria analysis.

    PubMed

    Wang, Junfeng; Wang, Yuhui; Bai, Junhong; Liu, Zhaowei; Song, Xinshan; Yan, Dengming; Abiyu, Asaminew; Zhao, Zhimiao; Yan, Denghua

    2017-03-01

    The constructed wetland coupled with biofilm-electrode reactor (CW-BER) is a novel technology to treat wastewater with a relatively high level of total inorganic nitrogen (TIN) concentration. The main objective of this study is to investigate the effects of C/Ns, TIN concentrations, current intensities, and pH on the removal of nitrogen in CW-BER; a control system (CW) was also constructed and operated with similar influent conditions. Results indicated that the current, inorganic carbon source and hydrogen generated by the micro-electric field could significantly improve the inorganic nitrogen removal with in CW-BER, and the enhancement of average removal rate on NH3-N, NO3-N, and TIN was approximately maintained at 5-28%, 5-26%, and 3-24%, respectively. The appropriate operation conditions were I=10mA and pH=7.5 in CW-BER. In addition, high-throughput sequencing analysis implied that the CW-BER reactor has been improved with the relative abundance of autotrophic denitrifying bacteria (Thiobacillus sp.).

  14. Autotrophic ammonia-oxidizing bacteria contribute minimally to nitrification in a nitrogen-impacted forested ecosystem

    Treesearch

    Fiona L. Jordan; J. Jason L. Cantera; Mark E. Fenn; Lisa Y. Stein

    2005-01-01

    Deposition rates of atmospheric nitrogenous pollutants to forests in the San Bernardino Mountains range east of Los Angeles, California, are the highest reported in North America. Acidic soils from the west end of the range are N-saturated and have elevated rates of N-mineralization, nitrification, and nitrate leaching. We assessed the impact of this heavy nitrogen...

  15. Start-up of autotrophic nitrogen removal reactors via sequential biocatalyst addition.

    PubMed

    Pynaert, Kris; Smets, Barth F; Beheydt, Daan; Verstraete, Willy

    2004-02-15

    A procedure for start-up of oxygen-limited autotrophic nitrification-denitrification (OLAND) in a lab-scale rotating biological contactor (RBC) is presented. In this one-step process, NH4+ is directly converted to N2 without the need for an organic carbon source. The approach is based on a sequential addition of two types of easily available biocatalyst to the reactor during start-up: aerobic nitrifying and anaerobic, granular methanogenic sludge. The first is added as a source of aerobic ammonia-oxidizing bacteria (AAOB), the second as a possible source of planctomycetes including anaerobic ammonia-oxidizing bacteria (AnAOB). The initial nitrifying biofilm serves as a matrix for anaerobic cell incorporation. By subsequently imposing oxygen limitation, one can create an optimal environment for autotrophic N removal. In this way, N removal of about 250 mg of N L(-1) d(-1) was achieved after 100 d treating a synthetic NH4+-rich wastewater. By gradually imposing higher loads on the reactor, the N elimination could be increased to about 1.8 g of N L(-1) d(-1) at 250 d. The resulting microbial community was compared with that of the inocula using general bacterial and AAOB- and planctomycete-specific PCR primers. Subsequently, the RBC reactor was shown to treat a sludge digestor effluent under suboptimal and strongly varying conditions. The RBC biocatalyst was also submitted to complete absence of oxygen in a fixed-film bioreactor (FFBR) and proved able to remove NH4+ with NO2- as electron acceptor (maximal 434 mg of NH4+-N (g of VSS)(-1) d(-1) on day 136). DGGE and real-time PCR analysis demonstrated that the RBC biofilm was dominated by members of the genus Nitrosomonas and close relatives of Kuenenia stuttgartiensis, a known AnAOB. The latter was enriched during FFBR operation, but AAOB were still present and the ratio planctomycetes/AAOB rRNA gene copies was about 4.3 after 136 d of reactor operation. Whether this relates to an active role of AAOB in the anoxic N

  16. Autotrophic ammonia oxidation by soil thaumarchaea

    PubMed Central

    Zhang, Li-Mei; Offre, Pierre R.; He, Ji-Zheng; Verhamme, Daniel T.; Nicol, Graeme W.; Prosser, James I.

    2010-01-01

    Nitrification plays a central role in the global nitrogen cycle and is responsible for significant losses of nitrogen fertilizer, atmospheric pollution by the greenhouse gas nitrous oxide, and nitrate pollution of groundwaters. Ammonia oxidation, the first step in nitrification, was thought to be performed by autotrophic bacteria until the recent discovery of archaeal ammonia oxidizers. Autotrophic archaeal ammonia oxidizers have been cultivated from marine and thermal spring environments, but the relative importance of bacteria and archaea in soil nitrification is unclear and it is believed that soil archaeal ammonia oxidizers may use organic carbon, rather than growing autotrophically. In this soil microcosm study, stable isotope probing was used to demonstrate incorporation of 13C-enriched carbon dioxide into the genomes of thaumarchaea possessing two functional genes: amoA, encoding a subunit of ammonia monooxygenase that catalyses the first step in ammonia oxidation; and hcd, a key gene in the autotrophic 3-hydroxypropionate/4-hydroxybutyrate cycle, which has been found so far only in archaea. Nitrification was accompanied by increases in archaeal amoA gene abundance and changes in amoA gene diversity, but no change was observed in bacterial amoA genes. Archaeal, but not bacterial, amoA genes were also detected in 13C-labeled DNA, demonstrating inorganic CO2 fixation by archaeal, but not bacterial, ammonia oxidizers. Autotrophic archaeal ammonia oxidation was further supported by coordinate increases in amoA and hcd gene abundance in 13C-labeled DNA. The results therefore provide direct evidence for a role for archaea in soil ammonia oxidation and demonstrate autotrophic growth of ammonia oxidizing archaea in soil. PMID:20855593

  17. Cultivation-independent detection of autotrophic hydrogen-oxidizing bacteria by DNA stable-isotope probing.

    PubMed

    Pumphrey, Graham M; Ranchou-Peyruse, Anthony; Spain, Jim C

    2011-07-01

    Knallgas bacteria are a physiologically defined group that is primarily studied using cultivation-dependent techniques. Given that current cultivation techniques fail to grow most bacteria, cultivation-independent techniques that selectively detect and identify knallgas bacteria will improve our ability to study their diversity and distribution. We used stable-isotope probing (SIP) to identify knallgas bacteria in rhizosphere soil of legumes and in a microbial mat from Obsidian Pool in Yellowstone National Park. When samples were incubated in the dark, incorporation of (13)CO(2) was H(2) dependent. SIP enabled the detection of knallgas bacteria that were not detected by cultivation, and the majority of bacteria identified in the rhizosphere soils were betaproteobacteria predominantly related to genera previously known to oxidize hydrogen. Bacteria in soil grew on hydrogen at concentrations as low as 100 ppm. A hydB homolog encoding a putative high-affinity NiFe hydrogenase was amplified from (13)C-labeled DNA from both vetch and clover rhizosphere soil. The results indicate that knallgas bacteria can be detected by SIP and populations that respond to different H(2) concentrations can be distinguished. The methods described here should be applicable to a variety of ecosystems and will enable the discovery of additional knallgas bacteria that are resistant to cultivation.

  18. Differentiation in nitrogen-converting activity and microbial community structure between granular size fractions in a continuous autotrophic nitrogen removal reactor.

    PubMed

    Qian, Feiyue; Chen, Xi; Wang, Jianfang; Shen, Yaoliang; Gao, Junjun; Mei, Juan

    2017-08-03

    The differentiation in nitrogen-converting activity and microbial community structure between granular size fractions in a continuous completely autotrophic nitrogen removal over nitrite (CANON) reactor, having a superior specific nitrogen removal rate of 0.24 g/(g VSS•d), were investigated by batch tests and high-throughput pyrosequencing analysis, respectively. Results revealed a high dissolved oxygen concentration (>1.8 mg/L) could result in efficient nitrite accumulation with small granules (0.2-0.6 mm in diameter), because aerobic ammonium-oxidizing bacteria (genus Nitrosomonas) predominated therein. Meanwhile, intermediate size granules (1.4-2.0 mm in diameter) showed the highest nitrogen removal activity of 40.4 mg/(g VSS•h) under sufficient oxygen supply, corresponding to the relative abundance ratio of aerobic to anaerobic ammonium-oxidizing bacteria (genus Candidatus Kuenenia) of 5.7. Additionally, a dual substrate competition for oxygen and nitrite would be considered as the main mechanism for repression of nitrite-oxidizing bacteria, and few Nitriospira spp. did not remarkably affect the overall performance of the reactor. Because all the granular size fractions could accomplish CANON process independently under oxygen limiting conditions, keeping a diversity of granular size would facilitate the stability of suspended growth CANON system.

  19. Application of nitrogen metabolism in autotrophic bacteria to chemosynthetic bioregeneration in space missions, supplement

    NASA Technical Reports Server (NTRS)

    Wixom, R. L.

    1974-01-01

    The chemolithotroph, Hydrogenomonas eutropha, was considered as a life support, bioregenerative system. This project focuses on several metabolic functions that are related to the proposed nitrogen cycle between man and this microbe. Specifically this organism has the capability to utilize as the sole nitrogen source such urine components as urea and fifteen individual amino acids, but not nine other amino acids. The effectiveness of utilization was high for many amino acids. Several specific growth inhibitions were also observed. The enzyme that catalyzes the incorporation of ammonia in the medium into amino acids was identified as a NADP-specific, L-glutamate dehydrogenase. This enzyme has a constitutive nature. This organism can synthesize all of its amino acids from carbon dioxide and ammonia. Therefore with the background literature of multiple pathways of individual amino acid biosyntheses, our evidence to date is consistent with the Hydrogeneomonas group having the same pathway of valine-isoleucine formation as the classical E. coli.

  20. Evaluation of autotrophic growth of ammonia-oxidizers associated with granular activated carbon used for drinking water purification by DNA-stable isotope probing.

    PubMed

    Niu, Jia; Kasuga, Ikuro; Kurisu, Futoshi; Furumai, Hiroaki; Shigeeda, Takaaki

    2013-12-01

    Nitrification is an important biological function of granular activated carbon (GAC) used in advanced drinking water purification processes. Newly discovered ammonia-oxidizing archaea (AOA) have challenged the traditional understanding of ammonia oxidation, which considered ammonia-oxidizing bacteria (AOB) as the sole ammonia-oxidizers. Previous studies demonstrated the predominance of AOA on GAC, but the contributions of AOA and AOB to ammonia oxidation remain unclear. In the present study, DNA-stable isotope probing (DNA-SIP) was used to investigate the autotrophic growth of AOA and AOB associated with GAC at two different ammonium concentrations (0.14 mg N/L and 1.4 mg N/L). GAC samples collected from three full-scale drinking water purification plants in Tokyo, Japan, had different abundance of AOA and AOB. These samples were fed continuously with ammonium and (13)C-bicarbonate for 14 days. The DNA-SIP analysis demonstrated that only AOA assimilated (13)C-bicarbonate at low ammonium concentration, whereas AOA and AOB exhibited autotrophic growth at high ammonium concentration. This indicates that a lower ammonium concentration is preferable for AOA growth. Since AOA could not grow without ammonium, their autotrophic growth was coupled with ammonia oxidation. Overall, our results point towards an important role of AOA in nitrification in GAC filters treating low concentration of ammonium.

  1. Enhancement of the complete autotrophic nitrogen removal over nitrite process in a modified single-stage subsurface vertical flow constructed wetland: Effect of saturated zone depth.

    PubMed

    Huang, Menglu; Wang, Zhen; Qi, Ran

    2017-06-01

    This study was conducted to explore enhancement of the complete autotrophic nitrogen removal over nitrite (CANON) process in a modified single-stage subsurface vertical flow constructed wetland (VSSF) with saturated zone, and nitrogen transformation pathways in the VSSF treating digested swine wastewater were investigated at four different saturated zone depths (SZDs). SZD significantly affected nitrogen transformation pathways in the VSSF throughout the experiment. As the SZD was 45cm, the CANON process was enhanced most effectively in the system owing to the notable enhancement of anammox. Correspondingly, the VSSF had the best TN removal performance [(76.74±7.30)%] and lower N2O emission flux [(3.50±0.22)mg·(m(2)·h)(-)(1)]. It could be concluded that autotrophic nitrogen removal via CANON process could become a primary route for nitrogen removal in the VSSF with optimized microenvironment that developed as a result of the appropriate SZD. Copyright © 2017 Elsevier Ltd. All rights reserved.

  2. Simultaneous removal of nitrogen and phosphorus from wastewater by means of FeS-based autotrophic denitrification.

    PubMed

    Li, Ruihua; Niu, Jianmin; Zhan, Xinmin; Liu, Bo

    2013-01-01

    The efficacy of iron(II) sulfide (FeS)-based autotrophic denitrification in simultaneous nitrogen and phosphorus removal from wastewater was studied with batch experiments. It was efficient at a wide pH range of 5-9, and temperature range of 10-40 °C. The concentrations of NH₄⁺-N, Mg²⁺ and HCO₃⁻ in the wastewater should be kept over 7.8, 0.24 and 30 mg L⁻¹ for efficient nitrate (NO₃⁻-N) reduction, respectively. The NO₃⁻-N removal rate increased from 0 to 82 mg L⁻¹ d⁻¹ and then leveled off when the NO₃⁻-N concentration increased from 0 to 415 mg L⁻¹ and then to 700 mg L⁻¹, respectively. The NO₃⁻-N removal rate quickly increased, leveled off, and then sharply decreased when the PO₄³⁻-P concentration increased from 0 to 0.1 mg L⁻¹, then to 114.0 mg L⁻¹, and further to 683.8 mg L⁻¹, respectively. The PO₄³⁻-P removal was over 98% when the PO₄³⁻-P concentration ranged 0-683.3 mg L⁻¹. During treatment of the secondary effluent of a local municipal wastewater treatment plant containing NO₃⁻-N of 14.9 mg L⁻¹ and total phosphorus (TP) of 3.9 mg L⁻¹, NO₃⁻-N was reduced to 1.1 mg L⁻¹ and TP was completely removed.

  3. N2O and NO emissions during autotrophic nitrogen removal in a granular sludge reactor--a simulation study.

    PubMed

    Van Hulle, S W H; Callens, J; Mampaey, K E; van Loosdrecht, M C M; Volcke, E I P

    2012-01-01

    This contribution deals with NO and N2O emissions during autotrophic nitrogen removal in a granular sludge reactor. Two possible model scenarios describing this emission by ammonium- oxidizing biomass have been compared in a simulation study of a granular sludge reactor for one-stage partial nitritation--Anammox. No significant difference between these two scenarios was noticed. The influence of the bulk oxygen concentration, granule size, reactor temperature and ammonium load on the NO and N2O emissions has been assessed. The simulation results indicate that emission maxima of NO and N2O coincide with the region for optimal Anammox conversion. Also, most of the NO and N2O are present in the off-gas, owing to the limited solubility of both gases. The size of granules needs to be large enough not to limit optimal Anammox activity, but not too large as this implies an elevated production of N2O. Temperature has a significant influence on N2O emission, as a higher temperature results in a better N-removal efficiency and a lowered N2O production. Statistical analysis of the results showed that there is a strong correlation between nitrite accumulation and N2O production. Further, three regions of operation can be distinguished: a region with high N2O, NO and nitrite concentration; a region with high N2 concentrations and, as such, high removal percentages; and a region with high oxygen and nitrate concentrations. There is some overlap between the first two regions, which is in line with the fact that maximum emission of NO and N2O coincides with the region for optimal Anammox conversion.

  4. Plant family identity distinguishes patterns of carbon and nitrogen stable isotope abundance and nitrogen concentration in mycoheterotrophic plants associated with ectomycorrhizal fungi.

    PubMed

    Hynson, Nicole A; Schiebold, Julienne M-I; Gebauer, Gerhard

    2016-09-01

    Mycoheterotrophy entails plants meeting all or a portion of their carbon (C) demands via symbiotic interactions with root-inhabiting mycorrhizal fungi. Ecophysiological traits of mycoheterotrophs, such as their C stable isotope abundances, strongly correlate with the degree of species' dependency on fungal C gains relative to C gains via photosynthesis. Less explored is the relationship between plant evolutionary history and mycoheterotrophic plant ecophysiology. We hypothesized that the C and nitrogen (N) stable isotope compositions, and N concentrations of fully and partially mycoheterotrophic species differentiate them from autotrophs, and that plant family identity would be an additional and significant explanatory factor for differences in these traits among species. We focused on mycoheterotrophic species that associate with ectomycorrhizal fungi from plant families Ericaceae and Orchidaceae. Published and unpublished data were compiled on the N concentrations, C and N stable isotope abundances (δ(13)C and δ(15)N) of fully (n = 18) and partially (n = 22) mycoheterotrophic species from each plant family as well as corresponding autotrophic reference species (n = 156). These data were used to calculate site-independent C and N stable isotope enrichment factors (ε). Then we tested for differences in N concentration, (13)C and (15)N enrichment among plant families and trophic strategies. We found that in addition to differentiating partially and fully mycoheterotrophic species from each other and from autotrophs, C and N stable isotope enrichment also differentiates plant species based on familial identity. Differences in N concentrations clustered at the plant family level rather than the degree of dependency on mycoheterotrophy. We posit that differences in stable isotope composition and N concentrations are related to plant family-specific physiological interactions with fungi and their environments. © The Author 2016. Published by Oxford University Press

  5. Plant family identity distinguishes patterns of carbon and nitrogen stable isotope abundance and nitrogen concentration in mycoheterotrophic plants associated with ectomycorrhizal fungi

    PubMed Central

    Hynson, Nicole A.; Schiebold, Julienne M.-I.; Gebauer, Gerhard

    2016-01-01

    Background and Aims Mycoheterotrophy entails plants meeting all or a portion of their carbon (C) demands via symbiotic interactions with root-inhabiting mycorrhizal fungi. Ecophysiological traits of mycoheterotrophs, such as their C stable isotope abundances, strongly correlate with the degree of species’ dependency on fungal C gains relative to C gains via photosynthesis. Less explored is the relationship between plant evolutionary history and mycoheterotrophic plant ecophysiology. We hypothesized that the C and nitrogen (N) stable isotope compositions, and N concentrations of fully and partially mycoheterotrophic species differentiate them from autotrophs, and that plant family identity would be an additional and significant explanatory factor for differences in these traits among species. We focused on mycoheterotrophic species that associate with ectomycorrhizal fungi from plant families Ericaceae and Orchidaceae. Methods Published and unpublished data were compiled on the N concentrations, C and N stable isotope abundances (δ13C and δ15N) of fully (n = 18) and partially (n = 22) mycoheterotrophic species from each plant family as well as corresponding autotrophic reference species (n = 156). These data were used to calculate site-independent C and N stable isotope enrichment factors (ε). Then we tested for differences in N concentration, 13C and 15N enrichment among plant families and trophic strategies. Key Results We found that in addition to differentiating partially and fully mycoheterotrophic species from each other and from autotrophs, C and N stable isotope enrichment also differentiates plant species based on familial identity. Differences in N concentrations clustered at the plant family level rather than the degree of dependency on mycoheterotrophy. Conclusions We posit that differences in stable isotope composition and N concentrations are related to plant family-specific physiological interactions with fungi and their environments. PMID

  6. Autotrophic nitrogen assimilation and carbon capture for microbial protein production by a novel enrichment of hydrogen-oxidizing bacteria.

    PubMed

    Matassa, Silvio; Verstraete, Willy; Pikaar, Ilje; Boon, Nico

    2016-09-15

    Domestic used water treatment systems are currently predominantly based on conventional resource inefficient treatment processes. While resource recovery is gaining momentum it lacks high value end-products which can be efficiently marketed. Microbial protein production offers a valid and promising alternative by upgrading low value recovered resources into high quality feed and also food. In the present study, we evaluated the potential of hydrogen-oxidizing bacteria to upgrade ammonium and carbon dioxide under autotrophic growth conditions. The enrichment of a generic microbial community and the implementation of different culture conditions (sequenced batch resp. continuous reactor) revealed surprising features. At low selection pressure (i.e. under sequenced batch culture at high solid retention time), a very diverse microbiome with an important presence of predatory Bdellovibrio spp. was observed. The microbial culture which evolved under high rate selection pressure (i.e. dilution rate D = 0.1 h(-1)) under continuous reactor conditions was dominated by Sulfuricurvum spp. and a highly stable and efficient process in terms of N and C uptake, biomass yield and volumetric productivity was attained. Under continuous culture conditions the maximum yield obtained was 0.29 g cell dry weight per gram chemical oxygen demand equivalent of hydrogen, whereas the maximum volumetric loading rate peaked 0.41 g cell dry weight per litre per hour at a protein content of 71%. Finally, the microbial protein produced was of high nutritive quality in terms of essential amino acids content and can be a suitable substitute for conventional feed sources such as fishmeal or soybean meal. Copyright © 2016 Elsevier Ltd. All rights reserved.

  7. [Abundance and Community Composition of Ammonia-Oxidizing Archaea in Two Completely Autotrophic Nitrogen Removal over Nitrite Systems].

    PubMed

    Gao, Jing-feng; Li, Ting; Zhang, Shu-jun; Fan, Xiao-yan; Pan, Kai-ling; Ma, Qian; Yuan, Ya-lin

    2015-08-01

    Ammonia oxidation is the first and rate-limiting step of nitrification, which was thought to be only performed by ammonia-oxidizing bacteria (AOB). In recent years, ammonia-oxidizing archaea (AOA) was also confirmed to take part in ammonia oxidation. The diversity and abundance of AOA have been investigated in various environments, however, little is known regarding the AOA in the completely autotrophic nitrogen removal over nitrite (CANON) wastewater treatment process. In this study, the abundance and diversity of AOA were investigated in the biofilm and flocculent activated sludge collected in a lab-scale (L) CANON system and a pilot-scale (P) CANON systems, respectively. The quantitative real time PCR (qPCR) was applied to investigate the abundance of AOA and the diversity of AOA was determined by polymerase chain reaction (PCR), cloning and sequencing. The qPCR results showed that the average abundance of AOA amoA gene of L and P was 2.42 x 10(6) copies x g(-1) dry sludge and 6.51 x 10(6) copies x g(-1) dry sludge, respectively. The abundance of AOA in biofilm was 10.1-14.1 times higher than that in flocculent activated sludge. For P system, the abundance of AOA in flocculent activated sludge was 1.8 times higher than that in biofilm. The results indicated that the abundance of AOA might be affected by different sludge morphology. The diversity of AOA in P system was extremely limited, only one OTU was observed, which was classified into Nitrosopumilus subcluster 5.2. The diversity of AOA in L system was higher, eight OTUs were observed, which were classified into five genera: Nitrososphaera subcluster 9, subcluster 8.1, subcluster 4.1, subcluster 1.1 and Nitrosopumilus subcluster 5.2. The diversity and abundance of AOA were different in CANON systems with different sludge morphology. AOA may play an important role in ammonia oxidation in CANON system.

  8. Characterization of an Autotrophic Nitrogen-Removing Biofilm from a Highly Loaded Lab-Scale Rotating Biological Contactor

    PubMed Central

    Pynaert, Kris; Smets, Barth F.; Wyffels, Stijn; Beheydt, Daan; Siciliano, Steven D.; Verstraete, Willy

    2003-01-01

    In this study, a lab-scale rotating biological contactor (RBC) treating a synthetic NH4+ wastewater devoid of organic carbon and showing high N losses was examined for several important physiological and microbial characteristics. The RBC biofilm removed 89% ± 5% of the influent N at the highest surface load of approximately 8.3 g of N m−2 day−1, with N2 as the main end product. In batch tests, the RBC biomass showed good aerobic and anoxic ammonium oxidation (147.8 ± 7.6 and 76.5 ± 6.4 mg of NH4+-N g of volatile suspended solids [VSS]−1 day−1, respectively) and almost no nitrite oxidation (< 1 mg of N g of VSS−1 day−1). The diversity of aerobic ammonia-oxidizing bacteria (AAOB) and planctomycetes in the biofilm was characterized by cloning and sequencing of PCR-amplified partial 16S rRNA genes. Phylogenetic analysis of the clones revealed that the AAOB community was fairly homogeneous and was dominated by Nitrosomonas-like species. Close relatives of the known anaerobic ammonia-oxidizing bacterium (AnAOB) Kuenenia stuttgartiensis dominated the planctomycete community and were most probably responsible for anoxic ammonium oxidation in the RBC. Use of a less specific planctomycete primer set, not amplifying the AnAOB, showed a high diversity among other planctomycetes, with representatives of all known groups present in the biofilm. The spatial organization of the biofilm was characterized using fluorescence in situ hybridization (FISH) with confocal scanning laser microscopy (CSLM). The latter showed that AAOB occurred side by side with putative AnAOB (cells hybridizing with probe PLA46 and AMX820/KST1275) throughout the biofilm, while other planctomycetes hybridizing with probe PLA886 (not detecting the known AnAOB) were present as very conspicuous spherical structures. This study reveals that long-term operation of a lab-scale RBC on a synthetic NH4+ wastewater devoid of organic carbon yields a stable biofilm in which two bacterial groups, thought

  9. 16S rRNA gene-based characterization of bacteria potentially associated with phosphate and carbonate precipitation from a granular autotrophic nitrogen removal bioreactor.

    PubMed

    Gonzalez-Martinez, Alejandro; Rodriguez-Sanchez, Alejandro; Rivadeneyra, María Angustias; Rivadeneyra, Almudena; Martin-Ramos, Daniel; Vahala, Riku; Gonzalez-Lopez, Jesús

    2017-01-01

    A bench-scale granular autotrophic nitrogen removal bioreactor (completely autotrophic nitrogen removal over nitrite (CANON) system) used for the treatment of synthetic wastewater was analyzed for the identification of microbiota with potential capacity for carbonate and phosphate biomineral formation. 16S ribosomal RNA (rRNA) gene-based studies revealed that different bacterial species found in the granular biomass could trigger the formation of phosphate and calcite minerals in the CANON bioreactor. iTag analysis of the microbial community in the granular biomass with potential ability to precipitate calcium carbonate and hydroxyapatite constituted around 0.79-1.32 % of total bacteria. Specifically, the possible hydroxyapatite-producing Candidatus Accumulibacter had a relative abundance of 0.36-0.38 % and was the highest phosphate-precipitating bacteria in the granular CANON system. With respect to calcite precipitation, the major potential producer was thought to be Stenotrophomonas with a 0.38-0.50 % relative abundance. In conclusion, our study showed evidences that the formation of hydroxyapatite and calcite crystals inside of the granular biomass of a CANON system for the treatment wastewater with high ammonium concentration was a biological process. Therefore, it could be suggested that microorganisms play an important role as a precipitation core and also modified the environment due to their metabolic activities.

  10. You are what you get from your fungi: nitrogen stable isotope patterns in Epipactis species.

    PubMed

    Schiebold, Julienne M-I; Bidartondo, Martin I; Karasch, Peter; Gravendeel, Barbara; Gebauer, Gerhard

    2017-05-01

    Partially mycoheterotrophic plants are enriched in 13 C and 15 N compared to autotrophic plants. Here, it is hypothesized that the type of mycorrhizal fungi found in orchid roots is responsible for variation in 15 N enrichment of leaf tissue in partially mycoheterotrophic orchids. The genus Epipactis was used as a case study and carbon and nitrogen isotope abundances of eight Epipactis species, fungal sporocarps of four Tuber species and autotrophic references were measured. Mycorrhizal fungi were identified using molecular methods. Stable isotope data of six additional Epipactis taxa and ectomycorrhizal and saprotrophic basidiomycetes were compiled from the literature. The 15 N enrichment of Epipactis species varied between 3·2 ± 0·8 ‰ ( E. gigantea ; rhizoctonia-associated) and 24·6 ± 1·6 ‰ ( E. neglecta ; associated with ectomycorrhizal ascomycetes). Sporocarps of ectomycorrhizal ascomycetes (10·7 ± 2·2 ‰) were significantly more enriched in 15 N than ectomycorrhizal (5·2 ± 4·0 ‰) and saprotrophic basidiomycetes (3·3 ± 2·1 ‰). As hypothesized, it is suggested that the observed gradient in 15 N enrichment of Epipactis species is strongly driven by 15 N abundance of their mycorrhizal fungi; i.e. ɛ 15 N in Epipactis spp. associated with rhizoctonias < ɛ 15 N in Epipactis spp. with ectomycorrhizal basidiomycetes < ɛ 15 N in Epipactis spp. with ectomycorrhizal ascomycetes and basidiomycetes < ɛ 15 N in Epipactis spp. with ectomycorrhizal ascomycetes.

  11. The demonstration of a novel sulfur cycle-based wastewater treatment process: sulfate reduction, autotrophic denitrification, and nitrification integrated (SANI®) biological nitrogen removal process.

    PubMed

    Lu, Hui; Wu, Di; Jiang, Feng; Ekama, George A; van Loosdrecht, Mark C M; Chen, Guang-Hao

    2012-11-01

    Saline water supply has been successfully practiced for toilet flushing in Hong Kong since 1950s, which saves 22% of freshwater in Hong Kong. In order to extend the benefits of saline water supply into saline sewage management, we have recently developed a novel biological organics and nitrogen removal process: the Sulfate reduction, Autotrophic denitrification, and Nitrification Integrated (SANI®) process. The key features of this novel process include elimination of oxygen demand in organic matter removal and production of minimal sludge. Following the success of a 500-day lab-scale trial, this study reports a pilot scale evaluation of this novel process treating 10 m(3) /day of 6-mm screened saline sewage in Hong Kong. The SANI® pilot plant consisted of a sulfate reduction up-flow sludge bed (SRUSB) reactor, an anoxic bioreactor for autotrophic denitrification and an aerobic bioreactor for nitrification. The plant was operated at a steady state for 225 days, during which the average removal efficiencies of both chemical oxygen demand (COD) and total suspended solids (TSS) at 87% and no excess sludge was purposefully withdrawn. Furthermore, a tracer test revealed 5% short circuit flow and a 34.6% dead zone in the SRUSB, indicating a good possibility to further optimize the treatment capacity of the process for full-scale application. Compared with conventional biological nitrogen removal processes, the SANI® process reduces 90% of waste sludge, which saves 35% of the energy and reduces 36% of fossil CO(2) emission. The SANI® process not only eliminates the major odor sources originating from primary treatment and subsequent sludge treatment and disposal during secondary saline sewage treatment, but also promotes saline water supply as an economic and sustainable solution for water scarcity and sewage treatment in water-scarce coastal areas.

  12. Stable Isotope Identification of Nitrogen Sources for United ...

    EPA Pesticide Factsheets

    We used natural abundance stable isotope data to evaluate nitrogen sources to U.S. west coast estuaries. We collected δ15N of macroalgae data and supplemented this with available data from the literature for estuaries from Mexico to Alaska. Stable isotope ratios of green macroalgae were compared to δ15N of dissolved inorganic nitrogen of oceanic and watershed end members. There was a latitudinal gradient in δ15N of macroalgae with southern estuaries being 7 per mil heavier than northern estuaries. Gradients in isotope data were compared to nitrogen sources estimated by the USGS using the SPARROW model. In California estuaries, the elevation of isotope data appeared to be related to anthropogenic nitrogen sources. In Oregon systems, the nitrogen levels of streams flowing into the estuaries are related to forest cover, rather than to developed land classes. In addition, the δ15N of macroalgae suggested that the ocean and nitrogen-fixing trees in the watersheds were the dominant nitrogen sources. There was also a strong gradient in δ15N of macroalgae with heavier sites located near the estuary mouth. In some Oregon estuaries, there was an elevation an elevation of δ15N above marine end members in the vicinity of wastewater treatment facility discharge locations, suggesting isotopes may be useful for distinguishing inputs along an estuarine gradient. Nutrients are the leading cause of water quality impairments in the United States, and as a result too

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

    PubMed

    Tiunov, A V

    2007-01-01

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

  14. Stable nitrogen isotopes in coastal macroalgae: geographic and anthropogenic variability.

    PubMed

    Viana, Inés G; Bode, Antonio

    2013-01-15

    Growing human population adds to the natural nitrogen loads to coastal waters. Both anthropogenic and natural nitrogen is readily incorporated in new biomass, and these different nitrogen sources may be traced by the measurement of the ratio of stable nitrogen isotopes (δ(15)N). In this study δ(15)N was determined in two species of macroalgae (Ascophyllum nodosum and Fucus vesiculosus), and in nitrate and ammonium to determine the relative importance of anthropogenic versus natural sources of nitrogen along the coast of NW Spain. Both algal species and nitrogen sources showed similar isotopic enrichment for a given site, but algal δ(15)N was not related to either inorganic nitrogen concentrations or δ(15)N in the water samples. The latter suggests that inorganic nitrogen inputs are variable and do not always leave an isotopic trace in macroalgae. However, a significant linear decrease in macroalgal δ(15)N along the coast is consistent with the differential effect of upwelling. Besides this geographic variability, the influence of anthropogenic nitrogen sources is evidenced by higher δ(15)N in macroalgae from rias and estuaries compared to those from open coastal areas and in areas with more than 15×10(3) inhabitants in the watershed. These results indicate that, in contrast with other studies, macroalgal δ(15)N is not simply related to either inorganic nitrogen concentrations or human population size but depends on other factors as the upwelling or the efficiency of local waste treatment systems. Copyright © 2012 Elsevier B.V. All rights reserved.

  15. Qualitative Distinction of Autotrophic and Heterotrophic Processes at the Leaf Level by Means of Triple Stable Isotope (C–O–H) Patterns

    PubMed Central

    Kimak, Adam; Kern, Zoltan; Leuenberger, Markus

    2015-01-01

    Foliar samples were harvested from two oaks, a beech, and a yew at the same site in order to trace the development of the leaves over an entire vegetation season. Cellulose yield and stable isotopic compositions (δ13C, δ18O, and δD) were analyzed on leaf cellulose. All parameters unequivocally define a juvenile and a mature period in the foliar expansion of each species. The accompanying shifts of the δ13C-values are in agreement with the transition from remobilized carbohydrates (juvenile period), to current photosynthates (mature phase). While the opponent seasonal trends of δ18O of blade and vein cellulose are in perfect agreement with the state-of-art mechanistic understanding, the lack of this discrepancy for δD, documented for the first time, is unexpected. For example, the offset range of 18 permil (oak veins) to 57 permil (oak blades) in δD may represent a process driven shift from autotrophic to heterotrophic processes. The shared pattern between blade and vein found for both oak and beech suggests an overwhelming metabolic isotope effect on δD that might be accompanied by proton transfer linked to the Calvin-cycle. These results provide strong evidence that hydrogen and oxygen are under different biochemical controls even at the leaf level. PMID:26635835

  16. Qualitative Distinction of Autotrophic and Heterotrophic Processes at the Leaf Level by Means of Triple Stable Isotope (C-O-H) Patterns.

    PubMed

    Kimak, Adam; Kern, Zoltan; Leuenberger, Markus

    2015-01-01

    Foliar samples were harvested from two oaks, a beech, and a yew at the same site in order to trace the development of the leaves over an entire vegetation season. Cellulose yield and stable isotopic compositions (δ(13)C, δ(18)O, and δD) were analyzed on leaf cellulose. All parameters unequivocally define a juvenile and a mature period in the foliar expansion of each species. The accompanying shifts of the δ(13)C-values are in agreement with the transition from remobilized carbohydrates (juvenile period), to current photosynthates (mature phase). While the opponent seasonal trends of δ(18)O of blade and vein cellulose are in perfect agreement with the state-of-art mechanistic understanding, the lack of this discrepancy for δD, documented for the first time, is unexpected. For example, the offset range of 18 permil (oak veins) to 57 permil (oak blades) in δD may represent a process driven shift from autotrophic to heterotrophic processes. The shared pattern between blade and vein found for both oak and beech suggests an overwhelming metabolic isotope effect on δD that might be accompanied by proton transfer linked to the Calvin-cycle. These results provide strong evidence that hydrogen and oxygen are under different biochemical controls even at the leaf level.

  17. Cultivation-Independent Detection of Autotrophic Hydrogen-Oxidizing Bacteria by DNA Stable-Isotope Probing ▿

    PubMed Central

    Pumphrey, Graham M.; Ranchou-Peyruse, Anthony; Spain, Jim C.

    2011-01-01

    Knallgas bacteria are a physiologically defined group that is primarily studied using cultivation-dependent techniques. Given that current cultivation techniques fail to grow most bacteria, cultivation-independent techniques that selectively detect and identify knallgas bacteria will improve our ability to study their diversity and distribution. We used stable-isotope probing (SIP) to identify knallgas bacteria in rhizosphere soil of legumes and in a microbial mat from Obsidian Pool in Yellowstone National Park. When samples were incubated in the dark, incorporation of 13CO2 was H2 dependent. SIP enabled the detection of knallgas bacteria that were not detected by cultivation, and the majority of bacteria identified in the rhizosphere soils were betaproteobacteria predominantly related to genera previously known to oxidize hydrogen. Bacteria in soil grew on hydrogen at concentrations as low as 100 ppm. A hydB homolog encoding a putative high-affinity NiFe hydrogenase was amplified from 13C-labeled DNA from both vetch and clover rhizosphere soil. The results indicate that knallgas bacteria can be detected by SIP and populations that respond to different H2 concentrations can be distinguished. The methods described here should be applicable to a variety of ecosystems and will enable the discovery of additional knallgas bacteria that are resistant to cultivation. PMID:21622787

  18. Stable Isotope Values of Nitrogen and Carbon in Particulate ...

    EPA Pesticide Factsheets

    Data set from “Patterns in stable isotope values of nitrogen and carbon in particulate matter from the Northwest Atlantic Continental Shelf, from the Gulf of Maine to Cape Hatteras” by Oczkowski et al. These are the data upon which all results and conclusion are made. Publishing the data allow for use by wider audience. Stable isotope dynamics on the shelf can inform both nearshore and open ocean research efforts, providing an important link along the marine continuum. To our knowledge, this data set is unique in its spatial coverage and variables measured.

  19. Microbial community and population dynamics of single-stage autotrophic nitrogen removal for dilute wastewater at the benchmark oxygen rate supply.

    PubMed

    Huang, Yu-Tzu; Chen, Shiou-Shiou; Lee, Po-Heng; Bae, Jaeho

    2013-11-01

    Microbial communities and their kinetic performance in a single-stage autotrophic nitrogen-removal filter at an optimal oxygen supply were examined to determine the presence and activity of denitrifiers, anaerobic ammonia-oxidizing (anammox), ammonia-oxidizing, and nitrite-oxidizing bacteria. To this end, different molecular biology techniques such as real-time quantitative polymerase chain reaction (qPCR) and biomarkers such as 16S rRNA revealed a diverse microbial community along the filter. It was important to survey the specific species of anammox bacteria using a newly designed Candidatus Brocadiafulgida (BF) specific primer, as well as Candidatus Brocadia anammoxidans (BA) and Candidatus Kuenenia stuttgartiensis (KS) specific primers. An unexpected finding was that the predominant anammox species switched from KS in concentrated wastewater to BA in dilute wastewaters. The Eckenfelder model of the NH3-N transformation along the filter was Se=S0 exp(-0.192D/L(2.3217)). These results provide a foundational understanding of the microbial structure and reaction kinetics in such systems.

  20. Intra-trophic isotopic discrimination of 15N/14N for amino acids in autotrophs: Implications for nitrogen dynamics in ecological studies

    USDA-ARS?s Scientific Manuscript database

    Metabolic reactions within heterotrophs cause discrimination in their stable nitrogen isotopic composition of amino acids (d15NAA) compared to their diets. Ecologists have exploited this measurable inter-trophic discrimination in the d15NAA value to estimate the trophic positions of heterotrophic an...

  1. Diversity and succession of autotrophic microbial community in high-elevation soils along deglaciation chronosequence

    NASA Astrophysics Data System (ADS)

    Kong, W.; Liu, J.

    2016-12-01

    Global warming has resulted in substantial glacier retreats in high-elevation areas, exposing deglaciated soils to harsh environmental conditions. Autotrophic microbes are pioneering colonizers in the deglaciated soils and provide nutrients to the extreme ecosystem devoid of vegetation. However, autotrophic communities remain less studied in deglaciated soils. We explored the diversity and succession of the cbbL gene encoding the large subunit of form I RubisCO, a key CO2-fixing enzyme, using molecular methods in deglaciated soils along a 10-year deglaciation chronosequence on the Tibetan Plateau. Our results demonstrated that the abundance of all types of form I cbbL (IA/B, IC and ID) rapidly increased in young soils (0-2.5 years old) and kept stable in old soils. Soil total organic carbon (TOC) and total nitrogen (TN) gradually increased along the chronosequence and both demonstrated positive correlations with the abundance of bacteria and autotrophs, indicating that soil TOC and TN originated from autotrophs. Form IA/B autotrophs, affiliated with cyanobacteria, exhibited a substantially higher abundance than IC and ID. Cyanobacterial diversity and evenness increased in young soils (<6 years old) and then remained stable. Our findings suggest that cyabobacteria play an important role in accumulating TOC and TN in the deglaciated soils.

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

    NASA Astrophysics Data System (ADS)

    Edenburn, L.; Michalski, G. M.

    2009-12-01

    The total isotopic composition of nitrate is used for identifying the origin and fate of nitrate in atmospheric, terrestrial and aquatic systems. The analysis of δ 18O, δ15N, and Δ17O values each give important and unique information about the sources and sinks of nitrate in these systems. Currently, there is no published method that allows for the simultaneous determination of δ18O, δ15N, and Δ17O of nitrate. Cascotti designed a novel method for measurement of δ18O and δ15N in nitrate but not Δ17O. This denitrifier method is based on the isotope ratio analysis of nitrous oxide generated by reduction of nitrate by cultured denitrifying bacteria. Kaiser then altered Cascotti's denitrifier method by converting N2O into O2 followed by the quantitative measurement δ18O and Δ17O, however δ15N was not measured. Here we present preliminary data on δ15N, δ18O, Δ17O values of N2 and O2 generated by the disproportionation of bacterial produced N2O. During the process of denitrification, nitrates are converted to nitrogen gas via a series of intermediate gaseous nitrogen oxide products. This is possible due to the presence of heterotrophic bacteria or autotrophic denitrifiers in select bacteria. Thus, we have chosen three distinct bacteria for the investigation of nitrate reduction for this study: Pseudomonas aureofaciens, Bacillus halodenitrificans, and Achromobacter cycloclastes. They each contain the copper-containing nitrite reductase necessary for the catalyzation of nitrate in order to complete the nitrogen cycle by returning N2 to the atmosphere. Bacillus halodenitrificans has the advantage of being an anaerobic halotolerant (salt-tolerant) denitrifier. Many of our samples have a high saline content; also, pre-concentration techniques using anion resin require elution using high ionic strength solutions. Further, high saline growth solutions limit contamination from other bacteria or organisms. Our efforts also focus on the conversion of N2O over a gold

  3. Patterns in Stable Isotope Values of Nitrogen and Carbon in ...

    EPA Pesticide Factsheets

    Stable isotope measurements of nitrogen and carbon (15N, 13ddC) are often used to characterize estuarine, nearshore, and open ocean ecosystems. Reliable information about the spatial distribution of base-level stable isotope values, often represented by primary producers, is critical to interpreting values in these ecosystems. While base-level isotope data are generally readily available for estuaries, nearshore coastal waters, and the open ocean, the continental shelf is less studied. To address this, and as a first step toward developing a surrogate for base-level isotopic signature in this region, we collected surface and deep water samples from the United States’ eastern continental shelf in the Western Atlantic Ocean, from the Gulf of Maine to Cape Hatteras, periodically between 2000 and 2013. During the study, particulate matter 15dN values ranged from 0.8 to 17.4‰, and 13dC values from −26.4 to −15.6‰over the region. We used spatial autocorrelation analysis and random forest modeling to examine the spatial trends and potential environmental drivers of the stable isotope values. We observed general trends toward lower values for both nitrogen and carbon isotopes at the seaward edge of the shelf. Conversely, higher 15dN and 13dC values were observed on the landward edge of the shelf, in particular in the southern portion of the sampling area. Across all sites, the magnitude of the difference between the 15dN of subsurface and surface particulate m

  4. Stable carbon and nitrogen isotope analysis of avian uric acid.

    PubMed

    Bird, Michael I; Tait, Elaine; Wurster, Christopher M; Furness, Robert W

    2008-11-01

    We report results obtained using a new technique developed to measure the stable-isotope composition of uric acid isolated from bird excreta (guano). Results from a diet-switch feeding trial using zebra finches suggest that the delta(13)C of uric acid in the guano equilibrates with the diet of the bird within 3 days of a change in diet, while the equilibration time for delta(15)N may be longer. The average carbon isotope discrimination between uric acid and food before the diet switch was +0.34 +/- 1 per thousand (1sigma) while after the diet switch this increased slightly to +0.83 +/- 0.7 per thousand (1sigma). Nitrogen isotope discrimination was +1.3 +/- 0.3 per thousand (1sigma) and +0.3 +/- 0.3 per thousand (1sigma) before and after the diet switch; however, it is possible that the nitrogen isotope values did not fully equilibrate with diet switch over the course of the experiment. Analyses of other chemical fractions of the guano (organic residue after uric acid extraction and non-uric acid organics solubilised during extraction) suggest a total range of up to 3 per thousand for both delta(13)C and delta(15)N values in individual components of a single bulk guano sample. The analysis of natural samples from a range of terrestrial and marine species demonstrates that the technique yields isotopic compositions consistent with the known diets of the birds. The results from natural samples further demonstrate that multiple samples from the same species collected from the same location yield similar results, while different species from the same location exhibit a range of isotopic compositions indicative of different dietary preferences. Given that many samples of guano can be rapidly collected without any requirement to capture specimens for invasive sampling, the stable-isotope analysis of uric acid offers a new, simple and potentially powerful tool for studying avian ecology and metabolism.

  5. Intra-trophic isotopic discrimination of (15)N/(14)N for amino acids in autotrophs: Implications for nitrogen dynamics in ecological studies.

    PubMed

    Takizawa, Yuko; Dharampal, Prarthana S; Steffan, Shawn A; Takano, Yoshinori; Ohkouchi, Naohiko; Chikaraishi, Yoshito

    2017-05-01

    The differential discrimination of nitrogen isotopes ((15)N/(14)N) within amino acids in consumers and their diets has been routinely used to estimate organismal tropic position (TP). Analogous isotopic discrimination can occur within plants, particularly in organs lacking chloroplasts. Such discrimination likely arises from the catabolic deamination of amino acids, resulting in a numerical elevation of estimated TP, within newly synthesized biomass. To investigate this phenomenon, we examined the (15)N/(14)N of amino acids (δ(15) NAA) in spring leaves and flowers from eight deciduous and two annual plants. These plants were classified on the basis of their time of bloom, plants that bloomed when their leaves were absent (Type I) versus plants that bloomed while leaves were already present (Type II). Based on the δ(15) NAA values from leaves, both plant types occupied comparable and ecologically realistic mean TPs (=1.0 ± 0.1, mean ± 1σ). However, the estimated TPs of flowers varied significantly (Type I: 2.2 ± 0.2; Type II: 1.0 ± 0.1). We hypothesize that these results can be interpreted by the following sequence of events: (1) Type I floral biomass is synthesized in absence of active photosynthesis; (2) the catabolic deamination of amino acids in particular, leaves behind (15)N in the residual pool of amino acids; and (3) the incorporation of these (15)N-enriched amino acids within the biomass of Type I flowers results in the numerical elevation of the TPs. In contrast, the actively photosynthesizing Type II leaves energetically sustain the synthesis of Type II flower biomass, precluding any reliance on catabolic deamination of amino acids. Amino acids within Type II flowers are therefore isotopically comparable to the Type II leaves. These findings demonstrate the idiosyncratic nature of the δ(15) NAA values within autotrophic organs and have implications for interpreting trophic hierarchies using primary producers and their consumers.

  6. Sediment Tracking Using Carbon and Nitrogen Stable Isotopes

    NASA Astrophysics Data System (ADS)

    Fox, J. F.; Papanicolaou, A.

    2002-12-01

    As landscapes are stripped of valuable, nutrient rich topsoils and streams are clouded with habitat degrading fine sediment, it becomes increasingly important to identify and mitigate erosive surfaces. Particle tracking using vegetative derived carbon (C) and nitrogen (N) isotopic signatures and carbon/nitrogen (C/N) atomic ratios offer a promising technique to identify such problematic sources. Consultants and researchers successfully use C, N, and other stable isotopes of water for hydrologic purposes, such as quantifying groundwater vs. surface water contribution to a hydrograph. Recently, C and N isotopes and C/N atomic ratios of sediment were used to determine sediment mass balance within estuarine environments. The current research investigates C and N isotopes and C/N atomic ratios of source sediment for two primary purposes: (1) to establish a blueprint methodology for estimating sediment source and erosion rates within a watershed using this isotopic technology coupled with mineralogy fingerprinting techniques, radionuclide transport monitoring, and erosion-transport models, and (2) to complete field studies of upland erosion processes, such as, solifluction, mass wasting, creep, fluvial erosion, and vegetative induced erosion. Upland and floodplain sediment profiles and riverine suspended sediment were sampled on two occasions, May 2002 and August 2002, in the upper Palouse River watershed of northern Idaho. Over 300 samples were obtained from deep intermountain valley (i.e. forest) and rolling crop field (i.e. agriculture) locations. Preliminary sample treatment was completed at the Washington State University Water Quality Laboratory where samples were dried, removed of organic constituents, and prepared for isotopic analysis. C and N isotope and C/N atomic ratio analyses was performed at the University of Idaho Natural Resources Stable Isotope Laboratory using a Costech 4010 Elemental Combustion System connected with a continuous flow inlet system to

  7. An integrated process of three-dimensional biofilm-electrode with sulfur autotrophic denitrification (3DBER-SAD) for wastewater reclamation.

    PubMed

    Hao, Ruixia; Meng, Chengcheng; Li, Jianbing

    2016-08-01

    A three-dimensional biofilm-electrode reactor (3DBER) was integrated with sulfur autotrophic denitrification (SAD) to improve nitrogen removal performance for wastewater reclamation. The impacts of influent carbon/nitrogen (C/N) ratio, electric current, and hydraulic retention time (HRT) were evaluated. The new process, abbreviated as 3DBER-SAD, achieved a more stable denitrification compared to the recently studied 3DBER in literature. Its nitrogen removal improved by about 45 % as compared to 3DBER, especially under low C/N ratio conditions. The results also revealed that the biofilm bacteria community of 3DBER-SAD contained 21.1 % of the genus Thauera, 19.3 % of the genus Thiobacillus and Sulfuricella, as well as 5.3 % of the genus Alicycliphilus, Pseudomonas, and Paracoccus. The synergy between these heterotrophic, sulfur autotrophic, and hydrogenotrophic denitrification bacteria was believed to cause the high and stable nitrogen removal performance under various operating conditions.

  8. Tracing the influence of sewage nitrogen in a coastal ecosystem using stable nitrogen isotopes.

    PubMed

    Savage, Candida

    2005-03-01

    This paper reviews the use of stable nitrogen isotopes (delta15N) to delineate the influence of sewage nitrogen (N) in coastal ecosystems, drawing extensively on the case of Himmerfjärden, a Baltic Sea bay that receives 15N-enriched tertiary treated sewage that is discharged mainly as dissolved inorganic N (DIN). Gradients of delta15N in macroalgae (Fucus vesiculosus) and surface sediments traced sewage-derived N to 24 km from the outfall but elevated delta15N values (> 7 per thousand) indicated that the sewage influence was most pronounced within 10 km. Comparison of macroalgal delta15N values before and after enhanced tertiary treatment showed a decrease in the spatial impact of sewage N from about 24 km to 12 km from the outfall and a decrease to more marine delta15N values in more recent growth tissues. Sedimentary delta15N records showed that sewage has had a dominant influence on organic matter production in the bay with dramatic increases in sedimentary delta15N during the years of maximum sewage N loads. In cases where sewage N introduces a distinct isotopic signature into a system and where it has had a dominant influence on organic matter production, delta15N values in biota and sediments can be used to trace the spatial and temporal influence of sewage N in aquatic ecosystems.

  9. Temporal variation of nitrogen balance within constructed wetlands treating slightly polluted water using a stable nitrogen isotope experiment.

    PubMed

    Zhang, Wanguang; Lei, Qiongye; Li, Zhengkui; Han, Huayang

    2016-02-01

    Slightly polluted water has become one of the main sources of nitrogen contaminants in recent years, for which constructed wetlands (CW) is a typical and efficient treatment. However, the knowledge about contribution of individual nitrogen removal pathways and nitrogen balance in constructed wetlands is still limited. In this study, a stable-isotope-addition experiment was performed in laboratory-scale constructed wetlands treating slightly polluted water to determine quantitative contribution of different pathways and temporal variation of nitrogen balance using Na(15)NO3 as tracer. Microbial conversion and substrate retention were found to be the dominant pathways in nitrogen removal contributing 24.4-79.9 and 8.9-70.7 %, respectively, while plant contributed only 4.6-11.1 % through direct assimilation but promoted the efficiency of other pathways. In addition, microbial conversion became the major way to remove N whereas nitrogen retained in substrate at first was gradually released to be utilized by microbes and plants over time. The findings indicated that N2 emission representing microbial conversion was not only the major but also permanent nitrogen removal process, thus keeping a high efficiency of microbial conversion is important for stable and efficient nitrogen removal in constructed wetlands.

  10. STABLE ISOTOPIC EVIDENCE OF CARBON AND NITROGEN USE IN CULTURED ECTOMYCORRHIZAL AND SAPROTROPHIC FUNGI

    EPA Science Inventory

    Stable isotopes in sporocarps have proven useful for inferring ectomycorrhizal or saprotrophic status and understanding carbon (C) and nitrogen (N) utilization. However, greater understanding of processes producing isotopic concentrations is needed. We measured natural abundanc...

  11. STABLE ISOTOPIC EVIDENCE OF CARBON AND NITROGEN USE IN CULTURED ECTOMYCORRHIZAL AND SAPROTROPHIC FUNGI

    EPA Science Inventory

    Stable isotopes in sporocarps have proven useful for inferring ectomycorrhizal or saprotrophic status and understanding carbon (C) and nitrogen (N) utilization. However, greater understanding of processes producing isotopic concentrations is needed. We measured natural abundanc...

  12. Influence of forest disturbance on stable nitrogen isotope ratios in soil and vegetation profiles

    Treesearch

    Jennifer D. Knoepp; Scott R. Taylor; Lindsay R. Boring; Chelcy F. Miniat

    2015-01-01

    Soil and plant stable nitrogen isotope ratios (15 N) are influenced by atmospheric nitrogen (N) inputs and processes that regulate organic matter (OM) transformation and N cycling. The resulting 15N patterns may be useful for discerning ecosystem differences in N cycling. We studied two ecosystems; longleaf pine wiregrass (...

  13. An investigation of a process for partial nitrification and autotrophic denitrification combined desulfurization in a single biofilm reactor.

    PubMed

    Liang, Zhiwei; Xu, Hanli; Wang, Yunlong; Yang, Shangyuan; Du, Ping

    2013-11-01

    In this study, a vertical submerged biofilm reactor was applied to investigate autotrophic partial nitrification/denitrification and simultaneous sulfide removal by using synthetic wastewater. The appropriate influent ratios of ammonia and sulfide needed to achieve partial autotrophic nitrification and denitrification were evaluated with influent ammonium nitrogen ranging from 54.6 to 129.8 mg L(-1) and sulfide concentrations ranging from 52.7 to 412.4 mg S L(-1). The results demonstrated that the working parameter was more stable when the sulfur/nitrogen ratio was set at 3:2, which yielded the maximum sulfur conversion. Batch experiments with different phosphate concentrations proved that a suitable phosphate buffer solution to control pH values could improve synchronous desulfurization denitrification process performance.

  14. Interactions between Thaumarchaea, Nitrospira and methanotrophs modulate autotrophic nitrification in volcanic grassland soil

    PubMed Central

    Daebeler, Anne; Bodelier, Paul LE; Yan, Zheng; Hefting, Mariet M; Jia, Zhongjun; Laanbroek, Hendrikus J

    2014-01-01

    Ammonium/ammonia is the sole energy substrate of ammonia oxidizers, and is also an essential nitrogen source for other microorganisms. Ammonia oxidizers therefore must compete with other soil microorganisms such as methane-oxidizing bacteria (MOB) in terrestrial ecosystems when ammonium concentrations are limiting. Here we report on the interactions between nitrifying communities dominated by ammonia-oxidizing archaea (AOA) and Nitrospira-like nitrite-oxidizing bacteria (NOB), and communities of MOB in controlled microcosm experiments with two levels of ammonium and methane availability. We observed strong stimulatory effects of elevated ammonium concentration on the processes of nitrification and methane oxidation as well as on the abundances of autotrophically growing nitrifiers. However, the key players in nitrification and methane oxidation, identified by stable-isotope labeling using 13CO2 and 13CH4, were the same under both ammonium levels, namely type 1.1a AOA, sublineage I and II Nitrospira-like NOB and Methylomicrobium-/Methylosarcina-like MOB, respectively. Ammonia-oxidizing bacteria were nearly absent, and ammonia oxidation could almost exclusively be attributed to AOA. Interestingly, although AOA functional gene abundance increased 10-fold during incubation, there was very limited evidence of autotrophic growth, suggesting a partly mixotrophic lifestyle. Furthermore, autotrophic growth of AOA and NOB was inhibited by active MOB at both ammonium levels. Our results suggest the existence of a previously overlooked competition for nitrogen between nitrifiers and methane oxidizers in soil, thus linking two of the most important biogeochemical cycles in nature. PMID:24858784

  15. Interactions between Thaumarchaea, Nitrospira and methanotrophs modulate autotrophic nitrification in volcanic grassland soil.

    PubMed

    Daebeler, Anne; Bodelier, Paul L E; Yan, Zheng; Hefting, Mariet M; Jia, Zhongjun; Laanbroek, Hendrikus J

    2014-12-01

    Ammonium/ammonia is the sole energy substrate of ammonia oxidizers, and is also an essential nitrogen source for other microorganisms. Ammonia oxidizers therefore must compete with other soil microorganisms such as methane-oxidizing bacteria (MOB) in terrestrial ecosystems when ammonium concentrations are limiting. Here we report on the interactions between nitrifying communities dominated by ammonia-oxidizing archaea (AOA) and Nitrospira-like nitrite-oxidizing bacteria (NOB), and communities of MOB in controlled microcosm experiments with two levels of ammonium and methane availability. We observed strong stimulatory effects of elevated ammonium concentration on the processes of nitrification and methane oxidation as well as on the abundances of autotrophically growing nitrifiers. However, the key players in nitrification and methane oxidation, identified by stable-isotope labeling using (13)CO2 and (13)CH4, were the same under both ammonium levels, namely type 1.1a AOA, sublineage I and II Nitrospira-like NOB and Methylomicrobium-/Methylosarcina-like MOB, respectively. Ammonia-oxidizing bacteria were nearly absent, and ammonia oxidation could almost exclusively be attributed to AOA. Interestingly, although AOA functional gene abundance increased 10-fold during incubation, there was very limited evidence of autotrophic growth, suggesting a partly mixotrophic lifestyle. Furthermore, autotrophic growth of AOA and NOB was inhibited by active MOB at both ammonium levels. Our results suggest the existence of a previously overlooked competition for nitrogen between nitrifiers and methane oxidizers in soil, thus linking two of the most important biogeochemical cycles in nature.

  16. VARYING STABLE NITROGEN ISOTOPIC RATIOS OF DIFFERENT COASTAL MARSH PLANTS AND THEIR RELATIONSHIPS WITH WASTEWATER NITROGEN AND LAND USE IN NEW ENGLAND, USA

    EPA Science Inventory

    Stable nitrogen isotopic ratios of coastal biota have been used as indicators of sources of anthropogenic nitrogen. In this study the relationships of the stable nitrogen isotopic ratios of salt marsh plants, Iva frutescens (L.), Phragmites australis (Cav.) Trin ex Steud, Spar...

  17. VARYING STABLE NITROGEN ISOTOPIC RATIOS OF DIFFERENT COASTAL MARSH PLANTS AND THEIR RELATIONSHIPS WITH WASTEWATER NITROGEN AND LAND USE IN NEW ENGLAND, USA

    EPA Science Inventory

    Stable nitrogen isotopic ratios of coastal biota have been used as indicators of sources of anthropogenic nitrogen. In this study the relationships of the stable nitrogen isotopic ratios of salt marsh plants, Iva frutescens (L.), Phragmites australis (Cav.) Trin ex Steud, Spar...

  18. Nitrogen Stable Isotope Composition of Various Fossil-fuel Combustion Nitrogen Oxide Sources

    NASA Astrophysics Data System (ADS)

    Walters, W.; Michalski, G. M.; Fang, H.

    2015-12-01

    Nitrogen oxides (NOx = NO + NO2) are important trace gases that impact atmospheric chemistry, air quality, and climate. In order to help constrain NOx source contributions, the nitrogen (N) stable isotope composition of NOx (δ15N-NOx) may be a useful indicator for NOx source partitioning. However, despite anthropogenic emissions being the most prevalent source of NOx, there is still large uncertainty in the δ15N-NOx values for anthropogenic sources. To this end, this study provides a detailed analysis of several fossil-fuel combustion NOx sources and their δ15N-NOx values. To accomplish this, exhaust or flue samples from several fossil-fuel combustion sources were sampled and analyzed for their δ15N-NOx that included airplanes, gasoline-powered vehicles not equipped with a catalytic converter, gasoline-powered lawn tools and utility vehicles, diesel-electric buses, diesel semi-trucks, and natural gas-burning home furnace and power plant. A relatively large range of δ15N-NOx values were measured from -28.1 to 0.3‰ for individual exhaust/flue samples with cold started diesel-electric buses contributing on average the lowest δ15N-NOx values at -20.9‰, and warm-started diesel-electric buses contributing on average the highest values of -1.7‰. The NOx sources analyzed in this study primarily originated from the "thermal production" of NOx and generally emitted negative δ15N-NOx values, likely due to the kinetic isotope effect associated with its production. It was found that there is a negative correlation between NOx concentrations and δ15N-NOx for fossil-fuel combustion sources equipped with catalytic NOx reduction technology, suggesting that the catalytic reduction of NOx may have an influence on δ15N-NOx values. Based on the δ15N-NOx values reported in this study and in previous studies, a δ15N-NOx regional and seasonal isoscape was constructed for the contiguous United States. The constructed isoscape demonstrates the seasonal importance of various

  19. Stable Isotope Identification of Nitrogen Sources for United States (U.S.) Pacific Coast Estuaries

    EPA Science Inventory

    We used natural abundance stable isotope data to evaluate nitrogen sources to U.S. west coast estuaries. We collected δ15N of macroalgae data and supplemented this with available data from the literature for estuaries from Mexico to Alaska. Stable isotope ratios of green m...

  20. Stable Isotope Identification of Nitrogen Sources for United States (U.S.) Pacific Coast Estuaries

    EPA Science Inventory

    We used natural abundance stable isotope data to evaluate nitrogen sources to U.S. west coast estuaries. We collected δ15N of macroalgae data and supplemented this with available data from the literature for estuaries from Mexico to Alaska. Stable isotope ratios of green m...

  1. Potential coupling effects of ammonia-oxidizing and anaerobic ammonium-oxidizing bacteria on completely autotrophic nitrogen removal over nitrite biofilm formation induced by the second messenger cyclic diguanylate.

    PubMed

    Wang, Chao; Liu, Sitong; Xu, Xiaochen; Zhao, Chuanqi; Yang, Fenglin; Wang, Dong

    2017-05-01

    The objective of this study was to investigate the influence of extracellular polymeric substance (EPS) on the coupling effects between ammonia-oxidizing bacteria (AOB) and anaerobic ammonium-oxidizing (anammox) bacteria for the completely autotrophic nitrogen removal over nitrite (CANON) biofilm formation in a moving bed biofilm reactor (MBBR). Analysis of the quantity of EPS and cyclic diguanylate (c-di-GMP) confirmed that the contents of polysaccharides and c-di-GMP were correlated in the AOB sludge, anammox sludge, and CANON biofilm. The anammox sludge secreted more EPS (especially polysaccharides) than AOB with a markedly higher c-di-GMP content, which could be used by the bacteria to regulate the synthesis of exopolysaccharides that are ultimately used as a fixation matrix, for the adhesion of biomass. Indeed, increased intracellular c-di-GMP concentrations in the anammox sludge enhanced the regulation of polysaccharides to promote the adhesion of AOB and formation of the CANON biofilm. Overall, the results of this study provide new comprehensive information regarding the coupling effects of AOB and anammox bacteria for the nitrogen removal process.

  2. Stable carbon and nitrogen isotopes in vertical peat profiles of natural and drained boreal peatlands

    NASA Astrophysics Data System (ADS)

    Nykänen, Hannu; Mpamah, Promise; Rissanen, Antti; Pitkänen, Aki; Turunen, Jukka; Simola, Heikki

    2015-04-01

    Peatlands form a significant carbon pool in the global carbon cycle. Change in peat hydrology, due to global warming is projected to change microbiological processes and peat carbon pool. We tested if bulk stable carbon and nitrogen isotopes serve as indicators of severe long term drying in peatlands drained for forestry. Depth profile analysis of peat, for their carbon and nitrogen content as well as their carbon and nitrogen stable isotopic signatures, were conducted for peatlands in southern and eastern Finland, having ombrotrophic and minerotrophic natural and corresponding drained pairs or separate drained sites. The selection of sites allowed us to compare changes due to different fertility and changes due to long term artificial drying. Drainage lasting over 40 years has led to changes in hydrology, vegetation, nutrient mineralization and respiration. Furthermore, increased nutrient uptake and possible recycling of peat nitrogen and carbon trough vegetation back to the peat surface, also possibly has an effect on the stable isotopic composition of peat carbon and nitrogen. We think that drainage induced changes somehow correspond to those caused by changed hydrology due to climate change. We will present data from these measurements and discuss their implications for carbon and nitrogen flows in peatlands.

  3. Origin of nitrogen in reforested lignite-rich mine soils revealed by stable isotope analysis

    SciTech Connect

    Abad Chabbi; Mathieu Sebilo; Cornelia Rumpel; Wolfgang Schaaf; Andre Mariotti

    2008-04-15

    Restoration of the nitrogen cycle is an important step in the recovery of an ecosystem after open-cast mining. Carbon and nitrogen in rehabilitated lignite containing mine soils can be derived from plant material as well as from lignite inherent to the parent substrate. We assessed the use elemental and stable carbon and nitrogen isotope measurements to trace the origin of soil nitrogen and applied these techniques to elucidate the origin of mineral N in the soil and the soil solution. The conceptual approach of this study included physical fractionation in addition to sampling of vegetation and soil from a lignite-containing mine site in Lusatia rehabilitated in 1985 with Pinus Nigra. We studied the elemental and isotopic composition of bulk samples as well as isolated fractions and soil solution. Our data indicate that the stable carbon and nitrogen isotopic composition of the soil samples are the result of mixing between plant material and substrate inherent lignite. {delta}{sup 15}N isotopes may be used as indicators of nitrogen contribution from plants to solid samples as well as soil solution. N-isotope composition of ammonia shows low spatial and interannual variability, despite strong concentration changes. Plant-derived nitrogen contributes in higher amounts to the soil solution compared to the bulk mineral soil. 45 refs., 3 figs., 3 tabs.

  4. Stable Isotope Values of Nitrogen and Carbon in Particulate Matter: Data

    EPA Science Inventory

    Data set from “Patterns in stable isotope values of nitrogen and carbon in particulate matter from the Northwest Atlantic Continental Shelf, from the Gulf of Maine to Cape Hatteras” by Oczkowski et al. These are the data upon which all results and conclusion are made...

  5. Stable Isotope Values of Nitrogen and Carbon in Particulate Matter: Data

    EPA Science Inventory

    Data set from “Patterns in stable isotope values of nitrogen and carbon in particulate matter from the Northwest Atlantic Continental Shelf, from the Gulf of Maine to Cape Hatteras” by Oczkowski et al. These are the data upon which all results and conclusion are made...

  6. STABLE NITROGEN ISOTOPES AS INDICATORS OF ANTHOPOGENIC ACTIVITIES IN SMALL FRESHWATER SYSTEMS

    EPA Science Inventory

    Stable nitrogen isotope ratios ( 15N) were measured in fish, mussel, and sediment samples taken from 17 small freshwater sites to examine food chain length and trophic position across sites affected by differing levels of anthropogenic activity. Both shoreline development and fis...

  7. PHYLOGENETIC AND ENVIRONMENTAL INFLUENCES ON NITROGEN STABLE ISOTOPE RATIOS IN SPOROCARPS OF ECTOMYCORRHIZAL FUNGI

    EPA Science Inventory

    It has been suggested that nitrogen stable isotope ratios (expressed as d15N) of fungus sporocarps, in conjunction with d15N data from other ecosystem compartments, can be used to elucidate key processes in forest N-cycling. Although results of previous studies generally support ...

  8. STABLE NITROGEN ISOTOPES AS INDICATORS OF ANTHOPOGENIC ACTIVITIES IN SMALL FRESHWATER SYSTEMS

    EPA Science Inventory

    Stable nitrogen isotope ratios ( 15N) were measured in fish, mussel, and sediment samples taken from 17 small freshwater sites to examine food chain length and trophic position across sites affected by differing levels of anthropogenic activity. Both shoreline development and fis...

  9. Stable carbon and nitrogen isotope analysis of TNT: two-dimensional source identification.

    PubMed

    Coffin, R B; Miyares, P H; Kelley, C A; Cifuentes, L A; Reynolds, C M

    2001-12-01

    Data from a combination of laboratory and fieldwork is presented to initiate testing of stable carbon and nitrogen isotope ratios to trace sources of TNT in contaminated soil and groundwater. Evaluation of these extraction methods resulted in 99.9 and 99.8% recovery of TNT with Soxhlet and solid-phase extraction (SPE), respectively. As a result of the high extraction efficiency, isotope fractionation did not occur, thus providing an accurate stable isotope value on TNT from laboratory and field samples. Subsequent experiments evaluated the stability of isotope signatures through incubations lasting up to four weeks with a 70% decline in the TNT concentration. During these experiments, no significant variation in stable carbon and nitrogen isotope ratios was measured. Five different sources of TNT, compared for stable carbon and nitrogen isotope ratios, showed a range of 4.2 and 15%, respectively. This large range in the isotope ratios suggests excellent potential to trace sources in a complex environment. Finally, a site was surveyed for concentrations and isotope values of TNT extracted from groundwaters. Values from this site were substantially different relative to the variation measured on standards and in laboratory incubation experiments. The data set indicates good potential to use stable isotopes to determine TNT sources and fate in the environment.

  10. Denitrification of groundwater using a sulfur-oxidizing autotrophic denitrifying anaerobic fluidized-bed MBR: performance and bacterial community structure.

    PubMed

    Zhang, Lili; Zhang, Chao; Hu, Chengzhi; Liu, Huijuan; Qu, Jiuhui

    2015-03-01

    This paper investigates a novel sulfur-oxidizing autotrophic denitrifying anaerobic fluidized bed membrane bioreactor (AnFB-MBR) that has the potential to overcome the limitations of conventional sulfur-oxidizing autotrophic denitrification systems. The AnFB-MBR produced consistent high-quality product water when fed by a synthetic groundwater with NO3 (-)-N ranging 25-80 mg/L and operated at hydraulic retention times of 0.5-5.0 h. A nitrate removal rate of up to 4.0 g NO3 (-)-N/Lreactord was attained by the bioreactor, which exceeded any reported removal capacity. The flux of AnFB-MBR was maintained in the range of 1.5-15 L m(-2) h(-1). Successful membrane cleaning was practiced with cleaning cycles of 35-81 days, which had no obvious effect on the AnFB-MBR performance. The (15) N-tracer analyses elucidated that nitrogen was converted into (15) N2-N and (15) N-biomass accounting for 88.1-93.1 % and 6.4-11.6 % of the total nitrogen produced, respectively. Only 0.3-0.5 % of removed nitrogen was in form of (15)N2O-N in sulfur-oxidizing autotrophic denitrification process, reducing potential risks of a significant amount of N2O emissions. The sulfur-oxidizing autotrophic denitrifying bacterial consortium was composed mainly of bacteria from Proteobacteria, Chlorobi, and Chloroflexi phyla, with genera Thiobacillus, Sulfurimonas, and Ignavibacteriales dominating the consortium. The pyrosequencing assays also suggested that the stable microbial communities corresponded to the elevated performance of the AnFB-MBR. Overall, this research described relatively high nitrate removal, acceptable flux, indicating future potential for the technology in practice.

  11. Comparing compound-specific and bulk stable nitrogen isotope trophic discrimination factors across multiple freshwater fish species and diets

    USDA-ARS?s Scientific Manuscript database

    The use of nitrogen stable isotopes for estimation of animal trophic position has become an indispensable approach in food web ecology. Compound-specific isotope analysis of amino acids is a new approach for estimating trophic position that may overcome key issues associated with nitrogen stable iso...

  12. [Effects of lipid extraction on stable carbon and nitrogen isotope analyses of Ommastrephes bartramii muscle].

    PubMed

    Gong, Yi; Chen, Xin-Jun; Gao, Chun-Xia; Li, Yun-Kai

    2014-11-01

    Stable isotope analysis (SIA) has become an important tool to investigate diet shift, habitat use and trophic structure of animal population. Muscle is considered to be the most common tissue for SIA, however, lipid content in muscle causes a considerable bias to the interpretation of isotopic ratios of animals. Neon flying squid (Ommastrephes bartramii) is an important economic cephalopod of Chinese distant water fishery, and plays a major role in marine ecosystems. In this study, the effects of lipid extraction on stable isotope ratios of the muscles of 53 neon flying squids were investigated and the interference mechanism of lipid in SIA was clarified with the aim of contrasting the suitability of different lipid correction models of stable carbon isotope. Results showed that the stable carbon and nitrogen isotopic values of non-lipid extracted samples significantly increased after lipid extractions by 0.71 per thousand and 0.47 per thousand, respectively, which suggested that lipid extraction in cephalopod isotope study is needed prior to stable carbon isotope analysis but not recommended for stable nitrogen isotope analysis. The results could help remove the effects of lipid contents and standardize SIA muscle samples, thereby getting better understanding of the isotopic change of neon flying squids in the future.

  13. Discrimination factors of carbon and nitrogen stable isotopes in meerkat feces.

    PubMed

    Montanari, Shaena

    2017-01-01

    Stable isotope analysis of feces can provide a non-invasive method for tracking the dietary habits of nearly any mammalian species. While fecal samples are often collected for macroscopic and genetic study, stable isotope analysis can also be applied to expand the knowledge of species-specific dietary ecology. It is somewhat unclear how digestion changes the isotope ratios of animals' diets, so more controlled diet studies are needed. To date, most diet-to-feces controlled stable isotope experiments have been performed on herbivores, so in this study I analyzed the carbon and nitrogen stable isotope ratios in the diet and feces of the meerkat (Suricata suricatta), a small omnivorous mammal. The carbon trophic discrimination factor between diet and feces (Δ(13)Cfeces) is calculated to be 0.1 ± 1.5‰, which is not significantly different from zero, and in turn, not different than the dietary input. On the other hand, the nitrogen trophic discrimination factor (Δ(15)Nfeces) is 1.5 ± 1.1‰, which is significantly different from zero, meaning it is different than the average dietary input. Based on data generated in this experiment and a review of the published literature, carbon isotopes of feces characterize diet, while nitrogen isotope ratios of feces are consistently higher than dietary inputs, meaning a discrimination factor needs to be taken into account. The carbon and nitrogen stable isotope values of feces are an excellent snapshot of diet that can be used in concert with other analytical methods to better understand ecology, diets, and habitat use of mammals.

  14. [Relationship between Fe, Al oxides and stable organic carbon, nitrogen in the yellow-brown soils].

    PubMed

    Heng, Li-Sha; Wang, Dai-Zhang; Jiang, Xin; Rao, Wei; Zhang, Wen-Hao; Guo, Chun-Yan; Li, Teng

    2010-11-01

    The stable organic carbon and nitrogen of the different particles were gained by oxidation of 6% NaOCl in the yellow-brown soils. The relationships between the contents of selective extractable Fe/Al and the stable organic carbon/nitrogen were investigated. It shown that amounts of dithionite-citrate-(Fe(d)) and oxalate-(Fe(o)) and pyrophosphate extractable (Fe(p)) were 6-60.8 g x kg(-1) and 0.13-4.8 g x kg(-1) and 0.03-0.47 g x kg(-1) in 2-250 microm particles, respectively; 43.1-170 g x kg(-1) and 5.9-14.0 g x kg(-1) and 0.28-0.78 g x kg(-1) in < 2 microm particles, respectively. The contents of oxalate-(Al(o)) and pyrophosphate extractable (Al(p)) were 0.08-1.34 g x kg(-10 and 0.11-0.47 g x kg(-1) in 2-250 microm particles, respectively; 2.96-6.20 g x kg(-1) and 0.38-0.78 g x kg(-1) in < 2 microm particles, respectively. And amounts of selective extractable Fe are generally higher in paddy yellow-brown soils than in arid yellow-brown soils, and that of selective extractable Al are lower in the former than in the latter. Amounts of the stable organic carbon and nitrogen, higher in paddy yellow-brown soils than in arid yellow-brown soils, were 0.93-6.0 g x kg(-1) and 0.05-0.36 g x kg(-1) in 2-250 microm particles, respectively; 6.05-19.3 g x kg(-1) and 0.61-2.1 g x kg(-1) in < 2 microm particles, respectively. The ratio of the stable organic carbon and nitrogen (C(stable)/N(stable)) were 9.50-22.0 in 2-250 microm particles and 7.43-11.54 in < 2 microm particles, respectively. The stabilization index (SI(C) and SI(N)) of the organic carbon and nitrogen were 14.3-50.0 and 11.9-55.6 in 2-250 microm particles, respectively; 53.72-88.80 and 40.64-70.0 in < 2 microm particles, respectively. According to SI, it is lower in arid yellow-brown soils than in paddy yellow-brown soils. The organic carbon and nitrogen are advantageously conserved in paddy yellow-brown soil. An extremely significant positive correlation of the stable organic carbon and nitrogen with selective

  15. Carbon and nitrogen stable isotope analysis of an Amphibolis griffithii seagrass bed

    NASA Astrophysics Data System (ADS)

    Smit, A. J.; Brearley, A.; Hyndes, G. A.; Lavery, P. S.; Walker, D. I.

    2005-11-01

    Western Australia has a rich diversity of seagrasses, many of which are meadow-forming species with a high diversity of associated epiphytes. Potential food sources and dominant invertebrates and fishes were collected in a non-quantitative sampling programme designed to examine the variability in naturally occurring isotopes ( 13C/ 12C and 15N/ 14N) within an Amphibolis griffithii dominated seagrass bed in Western Australia. The aims of this study were to determine the isotopic composition of the organisms, and to determine the sources of carbon available to consumers using the variations in the ratio of 15N/ 14N and 13C/ 12C among organisms in the seagrass assemblage. Autotrophs showed a wide distribution of δ13C values, with seagrass material significantly enriched in 13C relative to macroalgal sources by >10‰. This variation allowed us to successfully identify macroalgae as the main contributor of carbon to the trophic structure. δ15N ratios did not vary to the degree that would make it useful as tracer, but it was applied to estimating the total number of trophic transfers of nitrogen. Analysis of δ15N values suggested that four trophic positions were present, with fishes ( Acanthaluteres vittiger, Scobonichthys granulatus and Siphonognathus radiatus, Pelsartia humeralis, Pelates sexlineatus, Leviprora inops, Odax acroptilus and Notolabrus parilus) occupying the top two levels. δ13C of seston (20-200 μm) and sedimentary organic matter indicate that seagrass material is the main contributor to these two carbon pools, and that very little of it is incorporated into the trophic structure.

  16. Determination of the geographical origin of Chinese teas based on stable carbon and nitrogen isotope ratios*

    PubMed Central

    Zhang, Long; Pan, Jia-rong; Zhu, Cheng

    2012-01-01

    The objective of this study was to investigate the geographical origin of Chinese teas using carbon and nitrogen stable isotope ratio technology. The results showed that inter-provincial dispersion of teas in Guangdong (GD), Guangxi (GX), Hainan (HA), Fujian (FJ), Shandong (SD), Sichuan (SC), Chongqing (CQ), and Henan (HN) provinces was high, while in Zhejiang (ZJ), Hubei (HB), Yunnan (YN), and Anhui (AH) provinces, it was low. Tea samples from GD, GX, HA, and FJ provinces were clustered in one group and separated from those from AH and HB provinces. Thus, carbon and nitrogen stable isotope ratio technology could discriminate teas from among some provinces of China, but not from among others. Better separation might be obtained with a combination of isotopic ratios and other indexes, such as elemental data and organic components. PMID:23024049

  17. Compound-specific stable isotope analysis of nitrogen-containing intact polar lipids.

    PubMed

    Svensson, Elisabeth; Schouten, Stefan; Stam, Axel; Middelburg, Jack J; Sinninghe Damsté, Jaap S

    2015-12-15

    Compound-specific isotope analysis (CSIA) of nitrogen in amino acids has proven a valuable tool in many fields (e.g. ecology). Several intact polar lipids (IPLs) also contain nitrogen, and their nitrogen isotope ratios have the potential to elucidate food-web interactions or metabolic pathways. Here we have developed novel methodology for the determination of δ(15)N values of nitrogen-containing headgroups of IPLs using gas chromatography coupled with isotope-ratio mass spectrometry. Intact polar lipids with nitrogen-containing headgroups were hydrolyzed and the resulting compounds were derivatized by (1) acetylation with pivaloyl chloride for compounds with amine and hydroxyl groups or (2) esterification using acidified 2-propanol followed by acetylation with pivaloyl chloride for compounds with both carboxyl and amine groups. The δ(15)N values of the derivatives were subsequently determined using gas chromatography/combustion/isotope-ratio mass spectrometry. Intact polar lipids with ethanolamine and amino acid headgroups, such as phosphatidylethanolamine and phosphatidylserine, were successfully released from the IPLs and derivatized. Using commercially available pure compounds it was established that δ(15)N values of ethanolamine and glycine were not statistically different from the offline-determined values. Application of the technique to microbial cultures and a microbial mat showed that the method works well for the release and derivatization of the headgroup of phosphatidylethanolamine, a common IPL in bacteria. A method to enable CSIA of nitrogen of selected IPLs has been developed. The method is suitable for measuring natural stable nitrogen isotope ratios in microbial lipids, in particular phosphatidylethanolamine, and will be especially useful for tracing the fate of nitrogen in deliberate tracer experiments. Copyright © 2015 John Wiley & Sons, Ltd.

  18. Anammox-zeolite system acting as buffer to achieve stable effluent nitrogen values.

    PubMed

    Yapsakli, Kozet; Aktan, Cigdem Kalkan; Mertoglu, Bulent

    2017-02-01

    For a successful nitrogen removal, Anammox process needs to be established in line with a stable partial nitritation pretreatment unit since wastewater influent is mostly unsuitable for direct treatment by Anammox. Partial nitritation is, however, a critical bottleneck for the nitrogen removal since it is often difficult to maintain the right proportions of NO2-N and NH4-N during long periods of time for Anammox process. This study investigated the potential of Anammox-zeolite biofilter to buffer inequalities in nitrite and ammonium nitrogen in the influent feed. Anammox-zeolite biofilter combines the ion-exchange property of zeolite with the biological removal by Anammox process. Continuous-flow biofilter was operated for 570 days to test the response of Anammox-zeolite system for irregular ammonium and nitrite nitrogen entries. The reactor demonstrated stable and high nitrogen removal efficiencies (approximately 95 %) even when the influent NO2-N to NH4-N ratios were far from the stoichiometric ratio for Anammox reaction (i.e. NO2-N to NH4-N ranging from 0 to infinity). This is achieved by the sorption of surplus NH4-N by zeolite particles in case ammonium rich influent came in excess with respect to Anammox stoichiometry. Similarly, when ammonium-poor influent is fed to the reactor, ammonium desorption took place due to shifts in ion-exchange equilibrium and deficient amount were supplied by previously sorbed NH4-N. Here, zeolite acted as a preserving reservoir of ammonium where both sorption and desorption took place when needed and this caused the Anammox-zeolite system to act as a buffer system to generate a stable effluent.

  19. Nitrogen stable isotope variability in tissues of juvenile tilapia Oreochromis aureus: empirical and modelling results.

    PubMed

    Wang, Yinping; Gu, Xiaohong; Zeng, Qingfei; Mao, Zhigang; Wang, Wenxia

    2016-10-15

    Studies on diet or trophic interactions of organisms based on stable isotopes require accurate estimates of how quickly stable isotope ratios change in the investigated tissues. However, rates of isotope turnover in fish tissues, especially in omnivorous species, are poorly understood. We conducted a diet-shift study using juvenile tilapia to (i) empirically estimate the isotopic turnover rates of nitrogen in the dorsal muscle, liver, fin and backbone; (ii) model the relative contributions of metabolism and growth to the total isotopic turnover in each tissue; and (iii) develop a non-lethal approach for estimating body nitrogen stable isotope ratios for threatened or endangered species. Isotopic analyses were performed using a Flash EA CN elemental analyser coupled to a ThermoFinnigan Delta Plus mass spectrometer. Nitrogen isotopic turnover rates were consistently ranked in the order backbone > liver > muscle > fin due to the relatively lower metabolic rates of muscle and fin tissue. Backbone tissue turned over significantly faster than other tissues, suggesting the potential for a multiple-tissue stable isotope approach to the study of movement and trophic position over different time scales for omnivorous fish. However, fin tissue had the longest half-life, at 57.81 days, indicating that this tissue is more useful than muscle as a long-term dietary indicator. The change in nitrogen isotope ratios in dorsal muscle was mainly regulated by somatic growth, but metabolic activity markedly stimulated the turnover rate of backbone. This study is one of a few to demonstrate significant variation in the δ(15) N turnover rates among multiple tissues of a single organism, especially for omnivorous fish. Our results, to some extent, also indirectly contribute to the conservation of threatened or endangered species. Copyright © 2016 John Wiley & Sons, Ltd. Copyright © 2016 John Wiley & Sons, Ltd.

  20. Quantifying nitrogen process rates in a constructed wetland using natural abundance stable isotope signatures and stable isotope amendment experiments.

    PubMed

    Erler, Dirk V; Eyre, Bradley D

    2010-01-01

    This study describes the spatial variability in nitrogen (N) transformation within a constructed wetland (CW) treating domestic effluent. Nitrogen cycling within the CW was driven by settlement and mineralization of particulate organic nitrogen and uptake of NO3-. The concentration of NO3- was found to decrease, as the delta15N-NO3- signature increased, as water flowed through the CW, allowing denitrification rates to be estimated on the basis of the degree of fractionation of delta15N-NO3-. Estimates of denitrification hinged on the determination of a net isotope effect (eta), which was influenced byprocesses that enrich or deplete 15NO3- (e.g., nitrification), as well as the rate constants associated with the different processes involved in denitrification (i.e., diffusion and enzyme activity). The influence of nitrification on eta was quantified; however, it remained unclear how eta varied due to variability in denitrification rate constants. A series of stable isotope amendment experiments was used to further constrain the value of eta and calculate rates of denitrification, and nitrification, within the wetland. The maximum calculated rate of denitrification was 956 +/- 187 micromol N m(-2) h(-1), and the maximum rate of nitrification was 182 +/- 28.9 micromol N m(-2) h(-1). Uptake of NO3- was quantitatively more important than denitrification throughoutthe wetland. Rates of N cycling varied spatially within thewetland, with denitrification dominating in the downstream deoxygenated region of the wetland. Studies that use fractionation of N to derive rate estimates must exercise caution when interpreting the net isotope effect. We suggest a sampling procedure for future natural abundance studies that may help improve the accuracy of N cycling rate estimates.

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

    PubMed

    Svensson, Elisabeth; Schouten, Stefan; Hopmans, Ellen C; Middelburg, Jack J; Sinninghe Damsté, Jaap S

    2016-01-01

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

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

    PubMed Central

    Svensson, Elisabeth; Schouten, Stefan; Hopmans, Ellen C.; Middelburg, Jack J.; Sinninghe Damsté, Jaap S.

    2016-01-01

    Lipid extraction of biomass prior to stable isotope analysis is known to cause variable changes in the stable nitrogen isotopic composition (δ15N) of residual biomass. However, the underlying factors causing these changes are not yet clear. Here we address this issue by comparing the δ15N of bulk and residual biomass of several marine animal tissues (fish, crab, cockle, oyster, and polychaete), as well as the δ15N of the extracted lipids. As observed previously, lipid extraction led to a variable offset in δ15N of biomass (differences ranging from -2.3 to +1.8 ‰). Importantly, the total lipid extract (TLE) was highly depleted in 15N compared to bulk biomass, and also highly variable (differences ranging from -14 to +0.7 ‰). The TLE consisted mainly of phosphatidylcholines, a group of lipids with one nitrogen atom in the headgroup. To elucidate the cause for the 15N-depletion in the TLE, the δ15N of amino acids was determined, including serine because it is one of the main sources of nitrogen to N-containing lipids. Serine δ15N values differed by -7 to +2 ‰ from bulk biomass δ15N, and correlated well with the 15N depletion in TLEs. On average, serine was less depleted (-3‰) than the TLE (-7 ‰), possibly due to fractionation during biosynthesis of N-containing headgroups, or that other nitrogen-containing compounds, such as urea and choline, or recycled nitrogen contribute to the nitrogen isotopic composition of the TLE. The depletion in 15N of the TLE relative to biomass increased with the trophic level of the organisms. PMID:26731720

  3. Application of nitrogen stable isotope analysis in size-based marine food web and macroecological research.

    PubMed

    Jennings, Simon; Barnes, Carolyn; Sweeting, Christopher J; Polunin, Nicholas V C

    2008-06-01

    Interacting human and environmental pressures influence the structure and dynamics of marine food webs. To describe and predict the effects of these pressures, theoretical advances need to be supported by a capacity to validate the underlying models and assumptions. Here, we review recent applications of nitrogen stable isotope analysis in marine food web and macroecological research, with a focus on work that has paralleled a resurgence of interest in the development and application of size-based models. Nitrogen stable isotope data have been used to estimate intra- and inter-specific variation in trophic level, predator-prey size ratios, transfer efficiency, food chain length, relationships between predator and prey species diversity and the dynamics of energy use. Many of these estimates have contributed to the development, testing and parameterisation of food web and ecosystem models, some of which have been used to establish baselines for assessing the scale of human impacts. The interpretation of results depends on assumed fractionation but, when supported by sensitivity analyses and experimental validation, nitrogen stable isotope data provide valuable insights into the structuring of marine communities and ecosystems. John Wiley & Sons, Ltd

  4. Effects of nutritional restriction on nitrogen and carbon stable isotopes in growing seabirds.

    PubMed

    Williams, Cory T; Buck, C Loren; Sears, Justine; Kitaysky, Alexander S

    2007-08-01

    When using stable isotopes as dietary tracers it is essential to consider effects of nutritional state on isotopic fractionation. While starvation is known to induce enrichment of (15)N in body tissues, effects of moderate food restriction on isotope signatures have rarely been tested. We conducted two experiments to investigate effects of a 50-55% reduction in food intake on delta(15)N and delta(13)C values in blood cells and whole blood of tufted puffin chicks, a species that exhibits a variety of adaptive responses to nutritional deficits. We found that blood from puffin chicks fed ad libitum became enriched in (15)N and (13)C compared to food-restricted chicks. Our results show that (15)N enrichment is not always associated with food deprivation and argue effects of growth on diet-tissue fractionation of nitrogen stable isotopes (Delta(15)N) need to be considered in stable isotope studies. The decrease in delta(13)C of whole blood and blood cells in restricted birds is likely due to incorporation of carbon from (13)C-depleted lipids into proteins. Effects of nutritional restriction on delta(15)N and delta(13)C values were relatively small in both experiments (delta(15)N: 0.77 and 0.41 per thousand, delta(13)C: 0.20 and 0.25 per thousand) compared to effects of ecological processes, indicating physiological effects do not preclude the use of carbon and nitrogen stable isotopes in studies of seabird ecology. Nevertheless, our results demonstrate that physiological processes affect nitrogen and carbon stable isotopes in growing birds and we caution isotope ecologists to consider these effects to avoid drawing spurious conclusions.

  5. Urease gene-containing Archaea dominate autotrophic ammonia oxidation in two acid soils.

    PubMed

    Lu, Lu; Jia, Zhongjun

    2013-06-01

    The metabolic traits of ammonia-oxidizing archaea (AOA) and bacteria (AOB) interacting with their environment determine the nitrogen cycle at the global scale. Ureolytic metabolism has long been proposed as a mechanism for AOB to cope with substrate paucity in acid soil, but it remains unclear whether urea hydrolysis could afford AOA greater ecological advantages. By combining DNA-based stable isotope probing (SIP) and high-throughput pyrosequencing, here we show that autotrophic ammonia oxidation in two acid soils was predominately driven by AOA that contain ureC genes encoding the alpha subunit of a putative archaeal urease. In urea-amended SIP microcosms of forest soil (pH 5.40) and tea orchard soil (pH 3.75), nitrification activity was stimulated significantly by urea fertilization when compared with water-amended soils in which nitrification resulted solely from the oxidation of ammonia generated through mineralization of soil organic nitrogen. The stimulated activity was paralleled by changes in abundance and composition of archaeal amoA genes. Time-course incubations indicated that archaeal amoA genes were increasingly labelled by (13) CO2 in both microcosms amended with water and urea. Pyrosequencing revealed that archaeal populations were labelled to a much greater extent in soils amended with urea than water. Furthermore, archaeal ureC genes were successfully amplified in the (13) C-DNA, and acetylene inhibition suggests that autotrophic growth of urease-containing AOA depended on energy generation through ammonia oxidation. The sequences of AOB were not detected, and active AOA were affiliated with the marine Group 1.1a-associated lineage. The results suggest that ureolytic N metabolism could afford AOA greater advantages for autotrophic ammonia oxidation in acid soil, but the mechanism of how urea activates AOA cells remains unclear. © 2012 Society for Applied Microbiology and Blackwell Publishing Ltd.

  6. Pelagic nitrogen dynamics in the Vietnamese upwelling area according to stable nitrogen and carbon isotope data

    NASA Astrophysics Data System (ADS)

    Loick, Natalie; Dippner, Joachim; Doan, Hai Nhu; Liskow, Iris; Voss, Maren

    2007-04-01

    Upwelling and nitrogen (N) fixation provide new N for primary production off southern central Vietnam. Here we evaluate the roles of both N sources for zooplankton nutrition by comparing δ15N and δ13C values in nitrate, particulate organic matter (POM), and six net-plankton size fractions from monsoon and intermonsoon seasons. The δ13C values in POM and the net-plankton size fractions differed by 2-4‰ at any time. We assume that plankton from the POM filters was dominated by nano-and picoplankton as opposed to micro- and mesoplankton in the net-samples. The implications of this are discussed in terms of size differential pathways of C and N in the planktonic food web. We used δ15N to estimate the differences in N nutrition between the actual upwelling region and the oligotrophic area further offshore. The δ15N values of the net-plankton size fractions were depleted in δ15N by ca. 2‰ outside compared to inside the upwelling area during the monsoon season. We attribute these patterns to the additional utilization of N derived from N fixation. The concomitant findings of high N fixation rates reported earlier and low subthermocline nitrate (nitrate sub) values of 2.9-3.6‰ support this conclusion. Net-plankton δ15N values increased with size, pointing to the dominance of higher trophic levels in the larger size fractions. According to a two source mixing model N fixation may have provided up to 13% of the N demand in higher trophic levels.

  7. Reconstructing diet in Napoleon's Grand Army using stable carbon and nitrogen isotope analysis.

    PubMed

    Holder, Sammantha; Dupras, Tosha L; Jankauskas, Rimantas; Williams, Lana; Schultz, John

    2017-05-01

    Historical evidence has provided information regarding disease and mortality in Napoleon Bonaparte's Grand Army, but dietary information beyond individual soldier accounts remains scarce. The purpose of this research is to reconstruct the diets of Napoleon's multiethnic army who were associated with the Russian Campaign of 1812. We conducted stable carbon and nitrogen isotope ratio analysis on femoral bone collagen of 78 individuals recovered from a salvage excavation at the mass gravesite of Šiaurės miestelis in Vilnius, Lithuania. These individuals were later discovered to be Napoleonic soldiers and camp followers who participated in the 1812 Russian Campaign. Stable carbon isotope ratios range from -19.2‰ to -11.8‰, with a mean of -17.8‰ ± 1.5‰ (1 σ). Stable nitrogen isotope ratios range from 7.1‰ to 13.6‰, with a mean of 10.5‰ ± 1.4‰ (1 σ). Both δ(13) C and δ(15) N values show a wide range of variation. Stable isotope data indicate considerable dietary variation in this population associated with a multiethnic and socially stratified military population. Diets ranged from predominantly C3 -based to predominantly C4 -based, with varying inputs of terrestrial, freshwater, and marine animal protein. Comparison with other European populations further denotes the exceptional range of dietary variation of soldiers and camp followers in Napoleon's army. © 2017 Wiley Periodicals, Inc.

  8. Tracking Seasonal Habitats Using Carbon and Nitrogen Stable Isotopes of Osprey Primary Flight Feathers

    NASA Astrophysics Data System (ADS)

    Velinsky, D.; Zelanko, P.; Rice, N.

    2011-12-01

    The majority of bird migration studies use the latitudinal precipitation effect of hydrogen and oxygen stable isotopes of feathers to determine wintering and breeding grounds. Few studies have considered carbon and nitrogen stable isotopes to accomplish the same goal; exploiting the variation in dietary constitutes throughout yearly migration cycles. Also, there is no standard procedure of feather sampling; some use body, while others use wing feathers. This sampling discrepancy is not an issue for most migratory species since the majority of birds molt completely in one location, i.e. wintering verse breeding ground. Large birds of prey however, have a continuous molt that may last years, growing feathers on their breeding and wintering grounds. Therefore, a stable isotopic study of Osprey could not randomly sample feathers because it is impossible to know where individual feathers were grown. Here we present an in depth study of carbon and nitrogen stable isotopes from Mid-Atlantic Osprey primary flight feathers. Not only did we observe three signatures indicating the breeding ground and two distinct wintering grounds, we recorded dietary seasonality shifts within 2 to 3 year olds that remain on the wintering grounds for multiple years.

  9. [Research advances in identifying nitrate pollution sources of water environment by using nitrogen and oxygen stable isotopes].

    PubMed

    Mao, Wei; Liang, Zhi-wei; Li, Wei; Zhu, Yao; Yanng, Mu-yi; Jia, Chao-jie

    2013-04-01

    Water body' s nitrate pollution has become a common and severe environmental problem. In order to ensure human health and water environment benign evolution, it is of great importance to effectively identify the nitrate pollution sources of water body. Because of the discrepant composition of nitrogen and oxygen stable isotopes in different sources of nitrate in water body, nitrogen and oxygen stable isotopes can be used to identify the nitrate pollution sources of water environment. This paper introduced the fractionation factors of nitrogen and oxygen stable isotopes in the main processes of nitrogen cycling and the composition of these stable isotopes in main nitrate sources, compared the advantages and disadvantages of five pre-treatment methods for analyzing the nitrogen and oxygen isotopes in nitrate, and summarized the research advances in this aspect into three stages, i. e. , using nitrogen stable isotope alone, using nitrogen and oxygen stable isotopes simultaneously, and combining with mathematical models. The future research directions regarding the nitrate pollution sources identification of water environment were also discussed.

  10. Spatial and temporal variations in stable carbon (δ(13)C) and nitrogen (δ(15)N) isotopic composition of symbiotic scleractinian corals.

    PubMed

    Nahon, Sarah; Richoux, Nicole B; Kolasinski, Joanna; Desmalades, Martin; Ferrier Pages, Christine; Lecellier, Gael; Planes, Serge; Berteaux Lecellier, Véronique

    2013-01-01

    Tropical scleractinian corals are considered autotrophic as they rely mainly on photosynthesis-derived nutrients transferred from their photosymbionts. Corals are also able to capture and ingest suspended particulate organic matter, so heterotrophy can be an important supplementary trophic pathway to optimize coral fitness. The aim of this in situ study was to elucidate the trophic status of 10 coral species under contrasted environmental conditions in a French Polynesian lagoon. Carbon (δ(13)C) and nitrogen (δ(15)N) isotopic compositions of coral host tissues and photosymbionts were determined at 3 different fringing reefs during wet and dry seasons. Our results highlighted spatial variability in stable isotopic compositions of both coral host tissues and photosymbionts. Samples from the site with higher level of suspended particulate matter were (13)C-depleted and (15)N-enriched relative to corals and photosymbionts from less turbid sites. However, differences in both δ(13)C and δ(15)N between coral host tissues and their photosymbionts (Δ(host-photosymbionts 13)C and Δ(host-photosymbionts 15)N) were small (0.27 ± 0.76‰ and 1.40 ± 0.90‰, respectively) and similar at all sites, thus indicating no general increases in the heterotrophic pathway. Depleted δ(13)C and enriched δ(15)N values of coral host tissues measured at the most turbid site were explained by changes in isotopic composition of the inorganic nutrients taken up by photosymbionts and also by changes in rate of isotopic fractionation with environmental conditions. Our results also highlighted a lack of significant temporal variations in δ(13)C and δ(15)N values of coral host and photosymbiont tissues and in Δ(host-photosymbionts 13)C and Δ(host-photosymbionts 15)N values. This temporal stability indicated that corals remained principally autotrophic even during the wet season when photosymbiont densities were lower and the concentrations of phytoplankton were higher. Increased coral

  11. Stable isotope signatures confirm carbon and nitrogen gain through ectomycorrhizas in the ghost orchid Epipogium aphyllum Swartz.

    PubMed

    Liebel, H T; Gebauer, G

    2011-03-01

    Epipogium aphyllum is a rare Eurasian achlorophyllous forest orchid known to associate with fungi that form ectomycorrhizas, while closely related orchids of warm humid climates depend on wood- or litter-decomposer fungi. We conducted (13) C and (15) N stable isotope natural abundance analyses to identify the organic nutrient source of E. aphyllum from Central Norway. These data for orchid shoot tissues, in comparison to accompanying autotrophic plants, document C and N flow from ectomycorrhizal fungi to the orchid. DNA data from fungal pelotons in the orchid root cortex confirm the presence of Inocybe and Hebeloma, which are both fungi that form ectomycorrhizas. The enrichment factors for (13) C and (15) N of E. aphyllum are used to calculate a new overall average enrichment factor for mycoheterotrophic plants living in association with ectomycorrhizal fungi (ε(13) C ± 1 SD of 7.2 ± 1.6 ‰ and ε(15) N ± 1 SD of 12.8 ± 3.9 ‰). These can be used to estimate the fungal contribution to organic nutrient uptake by partially mycoheterotrophic plants where fully mycoheterotrophic plants are lacking. N concentrations in orchid tissue were unusually high and significantly higher than in accompanying autotrophic leaf samples. This may be caused by N gain of E. aphyllum from obligate ectomycorrhizal fungi. We show that E. aphyllum is an epiparasitic mycoheterotrophic orchid that depends on ectomycorrhizal Inocybe and Hebeloma to obtain C and N through a tripartite system linking mycoheterotrophic plants through fungi with forest trees.

  12. Identification of anthropogenic impact on nitrogen cycling using stable isotopes and distibuted hydrologic modeling

    NASA Astrophysics Data System (ADS)

    Macko, S. A.; O'Connell, M. T.; Fu, Y.

    2016-12-01

    The Najinhe watershed is a topographically diverse, heavily agricultural watershed in northeastern China that provides opportunities for identification of the impact of land use on nitrogen cycling. Land use, both historic and current, influences the biological processing of nitrogen in a particular area. Soil conditions, including moisture, texture, and organic content, control the capacity of a parcel for processing reactive nitrogen. Compounds derived from natural and anthropogenic sources exhibit characteristic ratios of stable isotopes of nitrogen and oxygen that serve as tracers of origin as well as integrators of biological processes. A distributed hydrologic model coupled with one focusing on reactive transport is able to help determine locations with the highest impact on the dissolved N in this system. Gaussian Markov Random Fields were used to determine the biogeochemical influence of model locations whereas δ15N measurements from NO3- and NH4+ in soil extracts were used to calibrate and validate model predictions based on measured precipitation and streamflow values. Sources were integrated using a Bayesian mixing model to determine likely fate and transport parameters for various N inputs to the watershed. The application of the coupled hydrologic and transport models to a village scale catchment suggests integration and expansion to larger watersheds on the basin scale. Identification of sensitive parcels on multiple spatial scales can direct targeted land management efforts to mitigate ecological and health effects of reactive N in surface waters.

  13. Isolation and stable nitrogen isotope analysis of ammonium ions in ammonium nitrate prills using sodium tetraphenylborate.

    PubMed

    Howa, John D; Lott, Michael J; Ehleringer, James R

    2014-07-15

    Because of the threat of bombings using improvised explosives containing ammonium nitrate (AN), law enforcement and intelligence communities have been interested in stable isotope techniques for tracking and discriminating AN sources. Separate analysis of the AN component ions ammonium and nitrate would add discriminatory power to these techniques. Ammonium ions in dissolved AN solution were isolated from samples by precipitation using sodium tetraphenylborate solution. We tested the isolation of ammonium from nitrates using solutions of ammonium and nitrate salts with different (15)N/(14)N isotope ratios. Ammonium tetraphenylborate and AN were separately analyzed for their (15)N/(14)N isotope ratios using EA-ConFlo-IRMS, and the (15)N/(14)N isotope ratios of the nitrate ions were calculated using mass balance. Ammonium and nitrate nitrogen isotope ratios were plotted as two separate variables. Isolation of ammonium precipitate from solutions containing dissolved nitrates did not influence the nitrogen isotope ratios of test ammonium salts. A survey set of 42 AN samples showed that the ammonium and nitrate (15)N/(14)N isotope ratios were not significantly correlated, and the paired mean differences were not statistically significant. Both ammonium and nitrate were depleted in (15)N relative to their theoretical atmospheric sources. Isolation of the ammonium ion from AN adds another dimension for the discrimination of forensic AN samples. This technique using sodium tetraphenylborate is robust and does not require specialized equipment. Our observations indicated that ammonium nitrogen and nitrate nitrogen have independent sources of isotopic variation. Copyright © 2014 John Wiley & Sons, Ltd.

  14. Seasonal variation in stable carbon and nitrogen isotope values of bats reflect environmental baselines.

    PubMed

    Popa-Lisseanu, Ana G; Kramer-Schadt, Stephanie; Quetglas, Juan; Delgado-Huertas, Antonio; Kelm, Detlev H; Ibáñez, Carlos

    2015-01-01

    The stable carbon and nitrogen isotope composition of animal tissues is commonly used to trace wildlife diets and analyze food chains. Changes in an animal's isotopic values over time are generally assumed to indicate diet shifts or, less frequently, physiological changes. Although plant isotopic values are known to correlate with climatic seasonality, only a few studies restricted to aquatic environments have investigated whether temporal isotopic variation in consumers may also reflect environmental baselines through trophic propagation. We modeled the monthly variation in carbon and nitrogen isotope values in whole blood of four insectivorous bat species occupying different foraging niches in southern Spain. We found a common pattern of isotopic variation independent of feeding habits, with an overall change as large as or larger than one trophic step. Physiological changes related to reproduction or to fat deposition prior to hibernation had no effect on isotopic variation, but juvenile bats had higher δ13C and δ15N values than adults. Aridity was the factor that best explained isotopic variation: bat blood became enriched in both 13C and 15N after hotter and/or drier periods. Our study is the first to show that consumers in terrestrial ecosystems reflect seasonal environmental dynamics in their isotope values. We highlight the danger of misinterpreting stable isotope data when not accounting for seasonal isotopic baselines in food web studies. Understanding how environmental seasonality is integrated in animals' isotope values will be crucial for developing reliable methods to use stable isotopes as dietary tracers.

  15. Sedimentary Nitrogen Stable Isotopes and Variations in Nutrient Cycling in the Holocene Black Sea

    NASA Astrophysics Data System (ADS)

    Fulton, J. M.; Arthur, M. A.

    2004-12-01

    Interpreting the evolution of organic matter production and preservation in anoxic basins such as the Holocene Black Sea depends on developing an understanding of changes in nutrient cycling within the water column with time. The organic fraction of sediments may preserve evidence of such changes in nutrient utilization. One model proposes changes in phosphorus availability as a driver for changes in algal productivity in the Black Sea. Nitrogen, the other macronutrient commonly considered to limit algal growth, is the focus of this study as we examine the nitrogen content and stable isotope variations of Black Sea sediments to determine what role it may have played in temporal changes in productivity and organic matter accumulation. High-resolution samples from five gravity cores collected by the RV Knorr 1988 expedition were analyzed for δ 15N-total and δ 13C-organic as well as their percent composition of organic carbon and total nitrogen. One core, GC71, was subjected to sequential extractions with KCl and hydrogen peroxide to remove exchangeable ammonia and labile organic matter respectively. The KCl extraction did not remove a statistically significant amount of ammonia, having no measurable effect on the percent nitrogen or δ 15N of the solid samples. The hydrogen peroxide extraction removed ca. 95% of the organic carbon and 85% of the nitrogen, leaving a relatively nitrogen-enriched residual material, probably due to ammonium fixed within the clay lattice. The fixed nitrogen has a minimal effect on the bulk nitrogen isotope values, suggesting the bulk nitrogen values are similar to the organic nitrogen signal. All cores examined were from below the modern Black Sea chemocline and are thought to have remained under anoxic bottom water continuously since soon after the incursion of saline Mediterranean water ca. 7800 years ago. Water depths for these cores range from 411 meters along the south margin of the sea to 2088 meters in the eastern Black Sea basin

  16. Hydrologic and Biological Controls on the Fate of Watershed-derived Nitrogen in Estuaries: Insights from "Whole-estuary" Stable Isotope Enrichments

    NASA Astrophysics Data System (ADS)

    Tobias, C.; Peterson, B.; Deegan, L.; Vallino, J.; Holmes, R.

    2005-05-01

    In situ nitrogen isotope tracer additions are becoming an increasingly widespread tool for understanding nitrogen fate and turnover in stream ecosystems. The approach however has only been attempted twice in estuaries. Isotope enrichment of these systems represents a several-fold increase in scale, and added challenges of bidirectional flow. Despite these potential limitations, the approach has yielded insights into nitrogen uptake, trophic transfer, and recycling on the scale of tens to hundreds of thousands of cubic meters of water and up to 4 kilometers of benthic area. The large-scale use of 15N tracer additions to estuaries has provided the unique ability to quantify multiple nitrogen (N) flow pathways under natural hydrologic and geochemical conditions. Estuarine 15N enrichment studies have been performed in two estuaries in the Plum Island LTER (Parker and Rowley Rivers) that differed in geomorphology, hydrology and biological structure. In each experiment 15N-nitrate tracer was added at the head of the estuaries in order to label watershed N entering the estuary and provided a "tag" for that N as it was processed in the estuary. 15N tracer released into the long water residence time Parker River was processed primarily (approx. 100 percent) through phytoplankton which subsequently supported high rates of secondary production in both the water column and benthos. In contrast, tracer released into the short water residence time Rowley River was primarily (75-80 percent of added 15N) advected, unaltered out of the estuary as nitrate. The 15N sinks that did exist within the Rowley were divided evenly between assimilation by benthic autotrophs (including uptake by marsh macrophytes) and denitrification. Recycling of the assimilated 15N back into the water column was a more important mechanism of N transfer than support of secondary production in the Rowley. Collectively, the use of large-scale stable 15N isotope additions in these contrasting estuaries has

  17. COMPARISON OF STABLE-NITROGEN (15N/14N) ISOTOPE RATIOS IN LARGE MOUTH BASS SCALES AND MUSCLE TISSUE

    EPA Science Inventory

    Stable-nitrogen (15N/14N) isotope ratios of fish tissue are currently used to determine trophic structure, contaminant bioaccumulation, and the level of anthropogenic nitrogen enrichment in aquatic systems. The most common tissue used for these measurements is fileted dorsal musc...

  18. Linking mercury, carbon, and nitrogen stable isotopes in Tibetan biota: Implications for using mercury stable isotopes as source tracers

    PubMed Central

    Xu, Xiaoyu; Zhang, Qianggong; Wang, Wen-Xiong

    2016-01-01

    Tibetan Plateau is located at a mountain region isolated from direct anthropogenic sources. Mercury concentrations and stable isotopes of carbon, nitrogen, and mercury were analyzed in sediment and biota for Nam Co and Yamdrok Lake. Biotic mercury concentrations and high food web magnification factors suggested that Tibetan Plateau is no longer a pristine site. The primary source of methylmercury was microbial production in local sediment despite the lack of direct methylmercury input. Strong ultraviolet intensity led to extensive photochemical reactions and up to 65% of methylmercury in water was photo-demethylated before entering the food webs. Biota displayed very high Δ199Hg signatures, with some highest value (8.6%) ever in living organisms. The δ202Hg and Δ199Hg in sediment and biotic samples increased with trophic positions (δ15N) and %methylmercury. Fish total length closely correlated to δ13C and Δ199Hg values due to dissimilar carbon sources and methylmercury pools in different living waters. This is the first mercury isotope study on high altitude lake ecosystems that demonstrated specific isotope fractionations of mercury under extreme environmental conditions. PMID:27151563

  19. Linking mercury, carbon, and nitrogen stable isotopes in Tibetan biota: Implications for using mercury stable isotopes as source tracers

    NASA Astrophysics Data System (ADS)

    Xu, Xiaoyu; Zhang, Qianggong; Wang, Wen-Xiong

    2016-05-01

    Tibetan Plateau is located at a mountain region isolated from direct anthropogenic sources. Mercury concentrations and stable isotopes of carbon, nitrogen, and mercury were analyzed in sediment and biota for Nam Co and Yamdrok Lake. Biotic mercury concentrations and high food web magnification factors suggested that Tibetan Plateau is no longer a pristine site. The primary source of methylmercury was microbial production in local sediment despite the lack of direct methylmercury input. Strong ultraviolet intensity led to extensive photochemical reactions and up to 65% of methylmercury in water was photo-demethylated before entering the food webs. Biota displayed very high Δ199Hg signatures, with some highest value (8.6%) ever in living organisms. The δ202Hg and Δ199Hg in sediment and biotic samples increased with trophic positions (δ15N) and %methylmercury. Fish total length closely correlated to δ13C and Δ199Hg values due to dissimilar carbon sources and methylmercury pools in different living waters. This is the first mercury isotope study on high altitude lake ecosystems that demonstrated specific isotope fractionations of mercury under extreme environmental conditions.

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

    NASA Technical Reports Server (NTRS)

    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.

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

    NASA Technical Reports Server (NTRS)

    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.

  2. Global spatial distributions of nitrogen and carbon stable isotope ratios of modern human hair.

    PubMed

    Hülsemann, Frank; Lehn, Christine; Schneider, Sabine; Jackson, Glen; Hill, Sarah; Rossmann, Andreas; Scheid, Nicole; Dunn, Philip J H; Flenker, Ulrich; Schänzer, Wilhelm

    2015-11-30

    Natural stable carbon (δ(13)C) and nitrogen isotope ratios (δ(15)N) of humans are related to individual dietary habits and environmental and physiological factors. In forensic science the stable isotope ratios of human remains such as hair and nail are used for geographical allocation. Thus, knowledge of the global spatial distribution of human δ(13)C and δ(15)N values is an essential component in the interpretation of stable isotope analytical results. No substantial global datasets of human stable isotope ratios are currently available, although the amount of available (published) data has increased within recent years. We have herein summarised the published data on human global δ(13)C andδ(15)N values (around 3600 samples) and added experimental values of more than 400 additional worldwide human hair and nail samples. In order to summarise isotope ratios for hair and nail samples correction factors were determined. The current available dataset of human stable isotope ratios is biased towards Europe and North America with only limited data for countries in Africa, Central and South America and Southeast Asia. The global spatial distribution of carbon isotopes is related to latitude and supports the fact that human δ(13)C values are dominated by the amount of C4 plants in the diet, either due to direct ingestion as plant food, or by its use as animal feed. In contrast, the global spatial distribution of human δ(15)N values is apparently not exclusively related to the amount of fish or meat ingested, but also to environmental factors that influence agricultural production. There are still a large proportion of countries, especially in Africa, where there are no available data for human carbon and nitrogen isotope ratios. Although the interpretation of modern human carbon isotope ratios at the global scale is quite possible, and correlates with the latitude, the potential influences of extrinsic and/or intrinsic factors on human nitrogen isotope ratios

  3. Stable isotopes of carbon and nitrogen in the study of organochlorine contaminants in albatrosses and petrels.

    PubMed

    Colabuono, Fernanda I; Barquete, Viviane; Taniguchi, Satie; Ryan, Peter G; Montone, Rosalinda C

    2014-06-15

    Carbon and nitrogen stable isotopes in albatrosses and petrels collected off southern Brazil were compared with concentrations of organochlorine contaminants (OCs). δ(13)C and δ(15)N values, as well as OCs concentrations, exhibited a high degree of variability among individuals and overlap among species. δ(13)C values reflected latitudinal differences among species, with lower values found in Wandering and Tristan Albatrosses and higher values found in Black-browed and Atlantic Yellow-nosed Albatrosses and White-chinned Petrels. Some relationships were found between OCs and stable isotopes, but in general a partial 'uncoupling' was observed between OCs concentrations and stable isotopes ratios (especially for δ(15)N). δ(13)C and δ(15)N values in Procellariiformes tissues during the non-breeding season appear to be a better indicator of foraging habitats than of trophic relationships, which may partially explain the high degree of variability between concentrations of OCs and stable isotopes ratios in birds with a diversified diet and wide foraging range. Copyright © 2014 Elsevier Ltd. All rights reserved.

  4. Using Stable Isotopes to Assess Connectivity: the Importance of Oceanic and Watershed Nitrogen Sources for Estuarine Primary Producers

    EPA Science Inventory

    Estuaries located at the interface of terrestrial and oceanic ecosystems receive nutrients from both ecosystems. Stable isotopes of primary producers and consumers are often used as an indicator of nutrient sources. We assembled natural abundance nitrogen stable isotope (δ15N) d...

  5. Trophic discrimination factors of stable carbon and nitrogen isotopes in hair of corn fed wild boar.

    PubMed

    Holá, Michaela; Ježek, Miloš; Kušta, Tomáš; Košatová, Michaela

    2015-01-01

    Stable isotope measurements are increasingly being used to gain insights into the nutritional ecology of many wildlife species and their role in ecosystem structure and function. Such studies require estimations of trophic discrimination factors (i.e. differences in the isotopic ratio between the consumer and its diet). Although trophic discrimination factors are tissue- and species-specific, researchers often rely on generalized, and fixed trophic discrimination factors that have not been experimentally derived. In this experimental study, captive wild boar (Sus scrofa) were fed a controlled diet of corn (Zea mays), a popular and increasingly dominant food source for wild boar in the Czech Republic and elsewhere in Europe, and trophic discrimination factors for stable carbon (Δ13C) and nitrogen (Δ15N) isotopes were determined from hair samples. The mean Δ13C and Δ15N in wild boar hair were -2.3‰ and +3.5‰, respectively. Also, in order to facilitate future derivations of isotopic measurements along wild boar hair, we calculated the average hair growth rate to be 1.1 mm d(-1). Our results serve as a baseline for interpreting isotopic patterns of free-ranging wild boar in current European agricultural landscapes. However, future research is needed in order to provide a broader understanding of the processes underlying the variation in trophic discrimination factors of carbon and nitrogen across of variety of diet types.

  6. Trophic Discrimination Factors of Stable Carbon and Nitrogen Isotopes in Hair of Corn Fed Wild Boar

    PubMed Central

    Holá, Michaela; Ježek, Miloš; Kušta, Tomáš; Košatová, Michaela

    2015-01-01

    Stable isotope measurements are increasingly being used to gain insights into the nutritional ecology of many wildlife species and their role in ecosystem structure and function. Such studies require estimations of trophic discrimination factors (i.e. differences in the isotopic ratio between the consumer and its diet). Although trophic discrimination factors are tissue- and species- specific, researchers often rely on generalized, and fixed trophic discrimination factors that have not been experimentally derived. In this experimental study, captive wild boar (Sus scrofa) were fed a controlled diet of corn (Zea mays), a popular and increasingly dominant food source for wild boar in the Czech Republic and elsewhere in Europe, and trophic discrimination factors for stable carbon (Δ13C) and nitrogen (Δ15N) isotopes were determined from hair samples. The mean Δ13C and Δ15N in wild boar hair were –2.3 ‰ and +3.5 ‰, respectively. Also, in order to facilitate future derivations of isotopic measurements along wild boar hair, we calculated the average hair growth rate to be 1.1 mm d-1. Our results serve as a baseline for interpreting isotopic patterns of free-ranging wild boar in current European agricultural landscapes. However, future research is needed in order to provide a broader understanding of the processes underlying the variation in trophic discrimination factors of carbon and nitrogen across of variety of diet types. PMID:25915400

  7. Stable carbon and nitrogen isotope discrimination and turnover in a small-bodied insectivorous lizard.

    PubMed

    Lattanzio, Matthew; Miles, Donald

    2016-12-01

    Laboratory experiments are useful for estimating the carbon and nitrogen isotope discrimination factors and turnover rates that are critical for drawing field-based inferences on consumer diets using stable isotopes. Although the utility of these discrimination factors is widely recognized, work in terrestrial systems has largely been limited to studies involving mammals and birds. In contrast, scant attention has been paid to the application of isotopic techniques to reptiles, despite their broad diversity in terms of numbers of species as well as their trophic roles. Here we estimate carbon and nitrogen isotope discrimination factors and turnover for the tree lizard (Urosaurus ornatus) using a diet-switch experiment. Lizards were collected from a C4-dominated grassland and then switched to C3-based diet (crickets) in the laboratory. We estimated discrimination by lizard claw tissue as Δ(13)C = 1.2 ± 0.1 ‰ for carbon and Δ(15)N = 0.7 ± 0.1 ‰ (mean ± 1 SE) for nitrogen, with 95 % turnover occurring after ∼15.5 days. These estimates should be appropriate for use in trophic studies of U. ornatus, and possibly other related small-bodied insectivorous lizards.

  8. Preliminary identification of ground-water nitrate sources using nitrogen and carbon stable isotopes, Kansas

    USGS Publications Warehouse

    Townsend, M.A.; Macko, S.A.

    2007-01-01

    Increasing nitrate-N in ground water is a problem in areas with limited ground-water supplies, such as central Kansas. Nitrate-N concentrations in ground water in the study area in Ellis County range from 0.9 to 26 mg/L. Calculated mean values observed in soil cores are 1.2-15 mg/kg. The ??15N signatures of the ground waters are more enriched (+16.8 to +28.7???) than those of the soils (+8.4 to +1 3.7???), strongly suggesting that nitrate-N sources are not from mineralized and labile nitrogen present in the unsaturated zone. Soil cores were collected near municipal wells to determine if soil nitrogen was a contributing source to the ground water. Increased ??15N of total nitrogen with depth suggests that microbial mineralization processes and possible denitrification or volatilization isotope enrichments have affected the observed ?? 15N signatures in the soil. However, the observed soil-nitrogen values are not of sufficient magnitude to explain the nitrate-N concentrations or associated ??15N values observed in the ground water. Stable carbon isotopes provide some supporting evidence that soils are not a major contributor to the observed nitrate-N concentration in the ground water. ?? 13C values of the dissolved organic carbon (DOC) in soils generally become more enriched with depth while corresponding ground-water ??13C (DOC) values are more depleted than in the overlying soils. Carbon isotope values of the soils are indicative of a C4 plant source that is enriched by microbial processes. The ??13C (DOC) of ground water indicates C3 values that may reflect impacts from animal-waste sources.

  9. Effects of caloric restriction on nitrogen and carbon stable isotope ratios in adult rat bone.

    PubMed

    Robertson, Kimberly L; Rowland, Neil E; Krigbaum, John

    2014-10-15

    Stable isotope analysis is a valuable technique for dietary estimation in ecological and archaeological research, yet many variables can potentially affect tissue stable isotope signatures. Controlled feeding studies across a range of species have consistently demonstrated impacts of caloric restriction on tissue stable isotope ratios, but most have focused on juvenile, fasting, and/or starving individuals, and most have utilized soft tissues despite the importance of bone for paleodietary analyses. The goal of this study was to determine whether temporally defined, moderate food restriction could affect stable carbon and/or nitrogen isotope ratios in adult mammalian bone - a tissue that arguably reflects long-term dietary signals. Adult rats fed a standard laboratory diet were restricted to 45% of ad libitum intakes for 3 or 6 months. Relevant anatomical and physiological parameters were measured to confirm that the restriction protocol resulted in significant nutritional stress and to provide independent data to facilitate interpretation of stable isotope ratios. Femoral bone δ(13)Ccollagen, δ(15)Ncollagen, and δ(13)Capatite values were determined by isotope ratio mass spectrometry. Calorie-restricted animals exhibited a small, yet significant enrichment in (15)Ncollagen compared with control animals, reflecting protein-calorie stress. While the δ(13)Ccollagen values did not differ, the δ(13)Capatite values revealed less enrichment in (13)C than in controls, reflecting catabolism of body fat. Independent anatomical and physiological data from these same individuals support these interpretations. Results indicate that moderate caloric restriction does not appreciably undermine broad interpretations of dietary signals in adult mammalian bone. Significant variability among individuals or groups, however, is best explained by marked differences in energy intake over variable timescales. An inverse relationship between the δ(13)Capatite and δ(15)Ncollagen

  10. Identification and characterization of land use driven nitrogen fluxes using stable isotopes and reactive hydrologic modeling

    NASA Astrophysics Data System (ADS)

    Macko, S. A.; O'Connell, M. T.

    2015-12-01

    The Najinhe watershed is a topographically diverse, mixed agricultural and urban region in northeastern China that provides opportunities for identification of the impact of land use on nitrogen cycling. In addition to agricultural soil amendments, seasonal variation in atmospheric flow introduces dry and wet deposition from urban and desert sources. Both agricultural amendments and atmospheric sources are significant non-point inputs of reactive N, at estimated annual rates of 450 kg/ha and 30 kg/ha respectively in the nearby North China Plain.Both historic and current land use has influenced the biological processing of nitrogen in a particular area. Soil conditions, including moisture, texture, and organic content, control the capacity of a parcel for processing reactive nitrogen. Compounds derived from natural and anthropogenic sources exhibit characteristic stable isotopes of nitrogen and oxygen that serve as tracers of origin as well as integrators of biological processes. Analysis of bulk soils (including both organic and inorganic N contents) in the system shows δ15N ranging from 1.3 - 8.6 ‰ suggesting varying influence of anthropogenic inputs, fertilizers, soil organic nitrogen, and atmospheric sources based on land use.A distributed hydrologic model coupled with one focusing on reactive transport is able to help determine locations with the highest impact on the dissolved N in this system. Spatial statistical methods are employed to determine the biogeochemical influence of model locations whereas δ18O on soil NO3- and δ15N measurements on NO3- and NH4+ in surface water and soil extracts are used to calibrate and validate model predictions based on measured precipitation and streamflow values. Sources are integrated using a Bayesian mixing model to determine likely fate and transport parameters for various N inputs to the watershed. The application of the coupled hydrologic and transport models to a landscape scale catchment suggests integration and

  11. Identification and characterization of anthropogenic nitrogen fluxes using stable isotopes and reactive hydrologic modeling

    NASA Astrophysics Data System (ADS)

    O'connell, M. T.; Macko, S. A.; Fu, Y.

    2014-12-01

    The Najinhe watershed is a topographically diverse, heavily agricultural watershed in northeastern China that provides opportunities for identification of the impact of land use on nitrogen cycling. In addition to agricultural soil amendments, seasonal variation in atmospheric flow introduces a signal of dry and wet deposition from urban and desert atmospheric N sources. Both agricultural amendments and atmospheric sources are significant sources of reactive N, at estimated annual rates of 450kg/hectare and 30kg/hectare respectively in the nearby North China Plain. Land use, both historic and current, influences the biological processing of nitrogen in a particular area. Soil conditions, including moisture, texture, and organic content, control the capacity of a parcel for processing reactive nitrogen. Compounds derived from natural and anthropogenic sources exhibit characteristic ratios of stable isotopes of nitrogen and oxygen that serve as tracers of origin as well as integrators of biological processes. Analysis of bulk soils (including both organic and inorganic N) in the system shows δ15N ranging from 1.3 - 8.6 ‰ suggesting varying influence of anthropogenic fertilizers, soil organic nitrogen, and atmospheric sources based on land use. A distributed hydrologic model coupled with one focusing on reactive transport is able to help determine locations with the highest impact on the dissolved N in this system. Spatial statistical methods are employed to determine the biogeochemical influence of model locations whereas δ18O and δ15N measurements from NO3- and NH4+ in surface water and soil extracts are used to calibrate and validate model predictions based on measured precipitation and streamflow values. Sources are integrated using a Bayesian mixing model to determine likely fate and transport parameters for various N inputs to the watershed. The application of the coupled hydrologic and transport models to a village scale catchment suggests integration and

  12. Nitrogen dynamics in subtropical fringe and basin mangrove forests inferred from stable isotopes.

    PubMed

    Reis, Carla Roberta Gonçalves; Nardoto, Gabriela Bielefeld; Rochelle, André Luis Casarin; Vieira, Simone Aparecida; Oliveira, Rafael Silva

    2017-03-01

    Mangroves exhibit low species richness compared to other tropical forests, but great structural and functional diversity. Aiming to contribute to a better understanding of the functioning of mangrove forests, we investigated nitrogen (N) dynamics in two physiographic types of mangroves (fringe and basin forests) in southeastern Brazil. Because fringe forests are under great influence of tidal flushing we hypothesized that these forests would exhibit higher N cycling rates in sediment and higher N losses to the atmosphere compared to basin forests. We quantified net N mineralization and nitrification rates in sediment and natural abundance of N stable isotopes (δ(15)N) in the sediment-plant-litter system. The fringe forest exhibited higher net N mineralization rates and δ(15)N in the sediment-plant-litter system, but net nitrification rates were similar to those of the basin forest. The results of the present study suggest that fringe forests exhibit higher N availability and N cycling in sediment compared to basin forests.

  13. Stable chromosomal integration of the entire nitrogen fixation gene cluster from Klebsiella pneumoniae in yeast.

    PubMed Central

    Zamir, A; Maina, C V; Fink, G R; Szalay, A A

    1981-01-01

    A bacterial plasmid containing the entire nitrogen fixation (nif) gene cluster (consisting of at least 15 genes) from Klebsiella pneumoniae was used in conjunction with an Escherichia coli-yeast shuttle plasmid containing the yeast his4 gene cluster to cotransform a his4- recipient strain of Saccharomyces cerevisiae. Of 87 histidine-independent clones screened, 2 contained nif DNA. Restriction and hybridization analyses showed that two copies of the nif plasmid (46 kilobases each) are integrated in tandem in the recipient chromosome by recombination between homologous regions in the transforming plasmids. Chromosomal integration was also verified by tetrad analysis, showing that the nif DNA behaved in meiosis like a Mendelian element. During mitotic growth, one of the two copies of the nif region is frequently lost. The remaining copy of nif is stable, even after 40 generations in nonselective medium. Images PMID:6267596

  14. Using stable isotope ratios to estimate atmospheric nitrogen fixed by cyanobacteria at the ecosystem scale.

    PubMed

    Woodland, Ryan J; Cook, Perran L M

    2014-04-01

    Diazotrophic cyanobacteria are capable of fixing atmospheric N2 to satisfy their physiological nitrogen requirements. This process can result in the transfer of substantial amounts of "new" diazotrophic nitrogen (ND) to aquatic ecosystems during blooms of these taxa. Using in situ measurements of plankton natural abundance stable isotope composition and a combination of underway and fixed site survey data, the total N(D) flux into the Gippsland Lakes estuary (Australia) was estimated during a summer bloom of the diazotrophic cyanobacterium Nodularia spumigena. Over the course of the bloom, N(D) increased in the upper water column of the estuary from 33% +/- 17% (mean +/- SD) to 73% +/- 13% of the standing pool of total particulate N. A conservative estimate of total N(D) flux (146 Mg) equates to an estimated 177% of the summer total N load and 22% of the annual total N load to the estuary. Combining natural abundance stable isotope measurements with relatively simple fixed and underway survey designs can provide a cost-effective approach for monitoring the N(D) flux into estuary or lacustrine environments. This approach relies on an isotopic differential between the diazotrophic and the non-diazotrophic components of the plankton community; it may not be appropriate in ecosystems that experience low-level blooms or blooms of intermittent N-fixing cyanobacteria. Large-scale blooms of diazotrophic cyanobacteria are considered uncommon in estuaries, yet it is clear that these blooms can represent major sources of new N to estuarine ecosystems when and where they occur.

  15. Stable Isotope Investigation of Marine-Terrestrial Nitrogen Linkages in Salmon Stream Ecosystems

    NASA Astrophysics Data System (ADS)

    Sayer, A. M.; Welker, J. M.; Rogers, M.; Rinella, D. J.; Sveinbjornsson, B.; Wipfli, M.

    2005-12-01

    Our research is addressing marine-terrestrial nitrogen linkages using stable isotope techniques (δ15N). Throughout coastal Alaska, salmon migrate each year into riparian systems transporting marine-produced biomass (carbon, phosphorous and nitrogen) that is decomposed, recycled and used by juvenile fish, invertebrates, carnivores and in some cases aquatic and terrestrial vegetation. These inputs of N into the terrestrial landscape have a host of cascading implications including the maintenance of biodiversity, enhanced survivorship of juvenile salmon and support of a complex food web that includes primary and secondary consumers (bears and eagles) and herbivores such as moose. A central question regarding this marine-terrestrial linkage is whether vegetation (aquatic or terrestrial) uses marine-derived N in metabolism and whether this fertilization effect increases leaf N contents, leads to higher rates of plant growth, results in higher rates of leaf gas exchange, and increases forage quantity and quality. By analyzing the δ15N-values of plants we will be able to fingerprint marine N use by plants and the degree to which this N contributes to the nitrogen budget of riparian vegetation.We are quantifying marine N use by aquatic and terrestrial vegetation (trees, shrubs and grasses) within the Kenai River watershed using a comparative approach sampling streams with annual salmon runs and streams without runs (waterfall inhibiting salmon spawning). We will determine the relationship between local hydrology and marine nutrient access using a multi-isotope approach which examines the relationship between plant water sources and relations and marine N use. We will ascertain the ecological importance of this N source by comparing the growth and ecophysiology of riparian vegetation along salmon impacted and non impacted streams. Initial results indicate that riparian vegetation along streams with large salmon runs have higher leaf N contents and enriched δ15N values

  16. Growth versus metabolic tissue replacement in mouse tissues determined by stable carbon and nitrogen isotope analysis

    NASA Astrophysics Data System (ADS)

    Macavoy, S. E.; Jamil, T.; Macko, S. A.; Arneson, L. S.

    2003-12-01

    Stable isotope analysis is becoming an extensively used tool in animal ecology. The isotopes most commonly used for analysis in terrestrial systems are those of carbon and nitrogen, due to differential carbon fractionation in C3 and C4 plants, and the approximately 3‰ enrichment in 15N per trophic level. Although isotope signatures in animal tissues presumably reflect the local food web, analysis is often complicated by differential nutrient routing and fractionation by tissues, and by the possibility that large organisms are not in isotopic equilibrium with the foods available in their immediate environment. Additionally, the rate at which organisms incorporate the isotope signature of a food through both growth and metabolic tissue replacement is largely unknown. In this study we have assessed the rate of carbon and nitrogen isotopic turnover in liver, muscle and blood in mice following a diet change. By determining growth rates, we were able to determine the proportion of tissue turnover caused by growth versus that caused by metabolic tissue replacement. Growth was found to account for approximately 10% of observed tissue turnover in sexually mature mice (Mus musculus). Blood carbon was found to have the shortest half-life (16.9 days), followed by muscle (24.7 days). Liver carbon turnover was not as well described by the exponential decay equations as other tissues. However, substantial liver carbon turnover was observed by the 28th day after diet switch. Surprisingly, these tissues primarily reflect the carbon signature of the protein, rather than carbohydrate, source in their diet. The nitrogen signature in all tissues was enriched by 3 - 5‰ over their dietary protein source, depending on tissue type, and the isotopic turnover rates were comparable to those observed in carbon.

  17. Stable isotopes of helium, nitrogen and carbon in a coastal submarine hydrothermal system

    NASA Astrophysics Data System (ADS)

    Vidal, Francisco V.; Welhan, John; Vidal, Victor M. V.

    1982-03-01

    Geothermal gases from submarine and subaerial hot springs in Ensenada, Baja California Norte, Mexico, were sampled for determination of gas chemistry and helium, nitrogen and stable carbon isotope composition. The submarine hot spring gas is primarily nitrogen (56.1% by volume) and methane (43.5% by volume), whereas nearby subaerial hot spring gases are predominantly nitrogen (95-99% by volume). The N 2/Ar ratios and σ 15N values of the subaerial hot spring gas indicate that it is atmospheric air, depleted in oxygen and enriched in helium. The submarine hot spring gas is most probably derived from marine sediments of Cretaceous age rich in organic matter. CH 4 is a major component of the gas mixture ( σ 13C = -44.05% 0), with only minor amounts of CO 2 ( σ13C= -10.46% 0). The σ 15N of N 2 is + 0.2% 0 with a very high N 2/Ar ratio of 160. The calculated isotopic equilibra tion temperature for CH 4CO 2 carbon exchange at depth in the Punta Banda submarine geothermal field is approximately 200°C in agreement with other geothermometry estimates. The 3He/ 4He ratios of the hot spring gases range from 0.3 to 0.6 times the atmospheric ratio, indicating that helium is predominantly derived from the radioactive decay of U and Th within the continental crust. Thus, not all submarine hydrothermal systems are effective vehicles for mantle degassing of primordial helium.

  18. Stable Isotopes Reveal Nitrogen Loading to Lake Tanganyika from Remote Shoreline Villages

    NASA Astrophysics Data System (ADS)

    Kelly, Brianne; Mtiti, Emmanuel; McIntyre, Peter B.; Vadeboncoeur, Yvonne

    2017-02-01

    Access to safe water is an ongoing challenge in rural areas in Tanzania where communities often lack access to improved sanitation. Methods to detect contamination of surface water bodies, such as monitoring nutrient concentrations and bacterial counts, are time consuming and results can be highly variable in space and time. On the northeast shore of Lake Tanganyika, Tanzania, the low population density coupled with the high potential for dilution in the lake necessitates the development of a sensitive method for detecting contamination in order to avoid human health concerns. We investigated the potential use of nitrogen and carbon stable isotopes of snail tissues to detect anthropogenic nutrient loading along the northeast shore of Lake Tanganyika. δ15N of snails was positively related to human population size in the nearest village, but only for villages with >4000 inhabitants. The areal footprint of villages within their watershed was also significantly correlated with snail δ15N, while agricultural land use and natural vegetation were not. Dissolved nutrient concentrations were not significantly different between village and reference sites. Our results indicate that nitrogen isotopes provide a sensitive index of local nutrient loading that can be used to monitor contamination of oligotrophic aquatic environments with low surrounding population densities.

  19. Stable Isotopes Reveal Nitrogen Loading to Lake Tanganyika from Remote Shoreline Villages.

    PubMed

    Kelly, Brianne; Mtiti, Emmanuel; McIntyre, Peter B; Vadeboncoeur, Yvonne

    2017-02-01

    Access to safe water is an ongoing challenge in rural areas in Tanzania where communities often lack access to improved sanitation. Methods to detect contamination of surface water bodies, such as monitoring nutrient concentrations and bacterial counts, are time consuming and results can be highly variable in space and time. On the northeast shore of Lake Tanganyika, Tanzania, the low population density coupled with the high potential for dilution in the lake necessitates the development of a sensitive method for detecting contamination in order to avoid human health concerns. We investigated the potential use of nitrogen and carbon stable isotopes of snail tissues to detect anthropogenic nutrient loading along the northeast shore of Lake Tanganyika. δ(15)N of snails was positively related to human population size in the nearest village, but only for villages with >4000 inhabitants. The areal footprint of villages within their watershed was also significantly correlated with snail δ(15)N, while agricultural land use and natural vegetation were not. Dissolved nutrient concentrations were not significantly different between village and reference sites. Our results indicate that nitrogen isotopes provide a sensitive index of local nutrient loading that can be used to monitor contamination of oligotrophic aquatic environments with low surrounding population densities.

  20. The effect of nitrogen loading on a brackish estuarine faunal community: A stable isotope approach

    USGS Publications Warehouse

    Keats, R.A.; Osher, L.J.; Neckles, H.A.

    2004-01-01

    Coastal ecosystems worldwide face increased nutrient enrichment from shoreline and watershed development and atmospheric pollution. We investigated the response of the faunal community of a small microtidal estuary dominated by Ruppia maritima (widgeon grass) in Maine, United States, to increased nitrogen loading using an in situ mesocosm enrichment experiment. Community response was characterized by assessing quantitative shifts in macroin-vertebrate community composition and identifying changes in food web structure using stable carbon and nitrogen isotope ratios of producers and consumers. The community was dominated by brackish water invertebrates including midge larvae, oligochaetes, damselfly larvae, amphipods, and ostracods. Experimental nutrient additions resulted in significantly lower densities of herbivorous chironomids and predatory damselflies and greater densities of deposit feeding oligochaetes. Grazing midge larvae (Chironomidae: Dicrotendipes, Cricotopus) consumed epiphytic algae under both natural and enriched conditions. Deposit feeding Chironomus was dependent on allochthonous sources of detritus under natural conditions and exhibited a shift to autochthonous sources of detritus under enriched conditions. Predatory Enallagma primarily consumed grazing chironomids under all but the highest loading conditions. Experimental nutrient loading resulted in an increase in generalist deposit feeders dependent on autochthonous sources of detritus.

  1. Stable carbon and nitrogen isotopes as a potential tool to differentiate pork from organic and conventional systems.

    PubMed

    Zhao, Yan; Yang, Shuming; Wang, Donghua

    2016-08-01

    Isotopic discrimination, dietary composition and feeding regime determine the carbon and nitrogen stable isotope ratios of animals. Accordingly, measurement of the stable isotope ratios of carbon and nitrogen can be a potential method to identify patterns of pork production. In the current study, we investigated the carbon and nitrogen isotopic ratio in pork from organic and conventional systems. The average carbon and nitrogen isotope ratios for various organic tissues, including hair, blood and defatted meat, were higher than those of conventionally raised ones. The discriminant analysis results based on the combination of carbon and nitrogen isotopic ratios in defatted meat reached a 100% correct classification. Furthermore, the variation in carbon and nitrogen stable isotope ratios of retail organic and conventional pork has been studied over 1 year. The results suggested that organic pork had a higher δ(13) C value than that of the conventional pork in all but three fortnights. Grouping of the δ(15) N data showed that the δ(15) N value in organic pork was higher than that of the conventional one throughout the whole year. The method established in the present study provides a potential detection that can be highly valuable to prevent fraudulent labelling of organic pork. © 2015 Society of Chemical Industry. © 2015 Society of Chemical Industry.

  2. Caution on the use of liquid nitrogen traps in stable hydrogen isotope-ratio mass spectrometry

    USGS Publications Warehouse

    Coplen, T.B.; Qi, H.

    2010-01-01

    An anomalous stable hydrogen isotopic fractionation of 4 ??? in gaseous hydrogen has been correlated with the process of adding liquid nitrogen (LN2) to top off the dewar of a stainless-steel water trap on a gaseous hydrogen-water platinum equilibration system. Although the cause of this isotopic fractionation is unknown, its effect can be mitigated by (1) increasing the capacity of any dewars so that they do not need to be filled during a daily analytic run, (2) interspersing isotopic reference waters among unknowns, and (3) applying a linear drift correction and linear normalization to isotopic results with a program such as Laboratory Information Management System (LIMS) for Light Stable Isotopes. With adoption of the above guidelines, measurement uncertainty can be substantially improved. For example, the long-term (months to years) ??2H reproducibility (1?? standard deviation) of nine local isotopic reference waters analyzed daily improved substantially from about 1 ??? to 0.58 ???. This isotopically fractionating mechanism might affect other isotope-ratio mass spectrometers in which LN2 is used as a moisture trap for gaseous hydrogen. ?? This article not subject to U.S. Copyright. Published 2010 by the American Chemical Society.

  3. Caution on the use of liquid nitrogen traps in stable hydrogen isotope-ratio mass spectrometry

    USGS Publications Warehouse

    Coplen, Tyler B.; Qi, Haiping

    2010-01-01

    An anomalous stable hydrogen isotopic fractionation of 4 ‰ in gaseous hydrogen has been correlated with the process of adding liquid nitrogen (LN2) to top off the dewar of a stainless-steel water trap on a gaseous hydrogen-water platinum equilibration system. Although the cause of this isotopic fractionation is unknown, its effect can be mitigated by (1) increasing the capacity of any dewars so that they do not need to be filled during a daily analytic run, (2) interspersing isotopic reference waters among unknowns, and (3) applying a linear drift correction and linear normalization to isotopic results with a program such as Laboratory Information Management System (LIMS) for Light Stable Isotopes. With adoption of the above guidelines, measurement uncertainty can be substantially improved. For example, the long-term (months to years) δ2H reproducibility (1& sigma; standard deviation) of nine local isotopic reference waters analyzed daily improved substantially from about 1‰ to 0.58 ‰. This isotopically fractionating mechanism might affect other isotope-ratio mass spectrometers in which LN2 is used as a moisture trap for gaseous hydrogen

  4. Tracing Fluxes Of Aquatic Production And Contaminants Into Terrestrial Food Webs With Nitrogen Stable Isotopes

    NASA Astrophysics Data System (ADS)

    Rivard, A.; Cabana, G.; Rainey, W.; Power, M.

    2005-05-01

    Biomagnifying contaminants such as mercury can be transported and redistributed across the watershed by streams and rivers. Their fate and effects on consumers depend on food web transfer both within and between aquatic and terrestrial ecosystems. The Truckee River (Ca/Ne) is heavily contaminated by Hg originating from century-old upstream mining operations. We used nitrogen stable isotope analysis to trace the incorporation of Hg transported by the Truckee and transferred by emerging aquatic insects into the riparian food web. N-isotope ratios and Hg of aquatic primary consumers were significantly elevated compared to that of terrestrial arthropods (13.3 vs 5.6 % and 110 vs 17 ngg-1). Estimates of dependence on aquatics in 16 riparian passerine bird species based on blood delta 15N ranged between 0.0 and 0.95 and were significantly related to Hg in blood. Similar correlations between Hg and delta 15N measured in tail tips of western fence lizard (Sceloporus occidentalis) collected at increasing distances from the river were observed. High inter-individual variation in bird Hg was highly correlated with delta 15N. These results show how stable isotopes and contaminant fluxes can reveal important food web linkages across aquatic/terrestrial ecotones.

  5. High-resolution nitrogen stable isotope sclerochronology of bivalve shell carbonate-bound organics

    NASA Astrophysics Data System (ADS)

    Gillikin, David P.; Lorrain, Anne; Jolivet, Aurélie; Kelemen, Zita; Chauvaud, Laurent; Bouillon, Steven

    2017-03-01

    Nitrogen stable isotope ratios (δ15N) of organic material have successfully been used to track food-web dynamics, nitrogen baselines, pollution, and nitrogen cycling. Extending the δ15N record back in time has not been straightforward due to a lack of suitable substrates in which δ15N records are faithfully preserved, thus sparking interest in utilizing skeletal carbonate-bound organic matter (CBOM) in mollusks, corals, and foraminifera. Here we test if calcite Pecten maximus shells from the Bay of Brest and the French continental shelf can be used as an archive of δ15N values over a large environmental gradient and at a high temporal resolution (approximately weekly). Bulk CBOM δ15N values from the growing tip of shells collected over a large nitrogen isotope gradient were strongly correlated with adductor muscle tissue δ15N values (R2 = 0.99, n = 6, p < 0.0001). We were able to achieve weekly resolution (on average) over the growing season from sclerochronological profiles of three shells, which showed large seasonal variations up to 3.4‰. However, there were also large inter-specimen differences (up to 2.5‰) between shells growing at the same time and location. Generally, high-resolution shell δ15N values follow soft-tissue δ15N values, but soft-tissues integrate more time, hence soft-tissue data are more time-averaged and smoothed. Museum-archived shells from the 1950s, 1965, and 1970s do not show a large difference in δ15N values through time despite expected increasing N loading to the Bay over this time, which could be due to anthropogenic N sources with contrasting values. Compiling shell CBOM δ15N data from several studies suggests that the offset between soft-tissue and shell δ15N values (Δtissue-shell) differs between calcite and aragonite shells. We hypothesize that this difference is caused by differences in amino acids used in constructing the different minerals, which should be specific to the CaCO3 polymorph being constructed. Future

  6. Carbon and Nitrogen Metabolism in Mycorrhizal Networks and Mycoheterotrophic Plants of Tropical Forests: A Stable Isotope Analysis1[W

    PubMed Central

    Courty, Pierre-Emmanuel; Walder, Florian; Boller, Thomas; Ineichen, Kurt; Wiemken, Andres; Rousteau, Alain; Selosse, Marc-André

    2011-01-01

    Most achlorophyllous mycoheterotrophic (MH) plants obtain carbon (C) from mycorrhizal networks and indirectly exploit nearby autotrophic plants. We compared overlooked tropical rainforest MH plants associating with arbuscular mycorrhizal fungi (AMF) to well-reported temperate MH plants associating with ectomycorrhizal basidiomycetes. We investigated 13C and 15N abundances of MH plants, green plants, and AMF spores in Caribbean rainforests. Whereas temperate MH plants and fungi have higher δ13C than canopy trees, these organisms displayed similar δ13C values in rainforests, suggesting differences in C exchanges. Although temperate green and MH plants differ in δ15N, they display similar 15N abundances, and likely nitrogen (N) sources, in rainforests. Contrasting with the high N concentrations shared by temperate MH plants and their fungi, rainforest MH plants had lower N concentrations than AMF, suggesting differences in C/N of exchanged nutrients. We provide a framework for isotopic studies on AMF networks and suggest that MH plants in tropical and temperate regions evolved different physiologies to adapt in diverging environments. PMID:21527422

  7. Understanding trophic interactions in host-parasite associations using stable isotopes of carbon and nitrogen.

    PubMed

    Nachev, Milen; Jochmann, Maik A; Walter, Friederike; Wolbert, J Benjamin; Schulte, S Marcel; Schmidt, Torsten C; Sures, Bernd

    2017-02-17

    Stable isotope analysis of carbon and nitrogen can deliver insights into trophic interactions between organisms. While many studies on free-living organisms are available, the number of those focusing on trophic interactions between hosts and their associated parasites still remains scarce. In some cases information about taxa (e.g. acanthocephalans) is completely missing. Additionally, available data revealed different and occasionally contrasting patterns, depending on the parasite's taxonomic position and its degree of development, which is most probably determined by its feeding strategy (absorption of nutrients through the tegument versus active feeding) and its localization in the host. Using stable isotope analysis of carbon and nitrogen we provided first data on the trophic position of an acanthocephalan species with respect to its fish host. Barbels (Barbus barbus) infected only with adult acanthocephalans Pomphorhynchus laevis as well as fish co-infected with the larval (L4) nematodes Eustrongylides sp. from host body cavity were investigated in order to determine the factors shaping host-parasite trophic interactions. Fish were collected in different seasons, to study also potential isotopic shifts over time, whereas barbels with single infection were obtained in summer and co-infected ones in autumn. Acanthocephalans as absorptive feeders showed lower isotope discrimination values of δ (15)N than the fish host. Results obtained for the acanthocephalans were in line with other parasitic taxa (e.g. cestodes), which exhibit a similar feeding strategy. We assumed that they feed mainly on metabolites, which were reprocessed by the host and are therefore isotopically lighter. In contrast, the nematodes were enriched in the heavier isotope δ (15)N with respect to their host and the acanthocephalans, respectively. As active feeders they feed on tissues and blood in the body cavity of the host and thus showed isotope discrimination patterns resembling those of

  8. Long-term Carbon and Nitrogen Dynamics at SPRUCE Revealed through Stable Isotopes in Peat Profiles

    NASA Astrophysics Data System (ADS)

    Hobbie, E. A.

    2015-12-01

    Carbon and nitrogen turnover in peatlands is of considerable interest because peat is a large reservoir of stored carbon that could emit greenhouse gases in response to climate change. Because peat cores preserve a long-term record of system carbon and nitrogen dynamics, it is possible to use stable isotopes as markers of changes in carbon (C) and nitrogen (N) dynamics over time. Here, we used δ15N and δ13C patterns throughout the depth profile of peat cores to understand controls over C-N cycling in the Marcell S1 forested bog in northern Minnesota. In multiple regression analyses, δ15N and δ13C correlated strongly with depth, plot location, %C, %N, and each other. Negative correlation of δ15N with %N presumably reflected removal of 15N-depleted N via denitrification, diffusion, or plant N transfer via mycorrhizal fungi. A step increase in the depth coefficient for δ15N of ~3‰ from -25 cm to -35 cm suggested that the N removal process primarily operates at a discrete depth corresponding to the juncture between aerobic and anaerobic layers defined by the water table. Higher δ15N and lower δ13C in plots closer to uplands may reflect distinct hydrology and accompanying shifts in C and N dynamics in the lagg area fringing the bog. The Suess effect (declining δ13CO2 since the Industrial Revoluation) and aerobic decomposition lowered δ13C in recent surficial samples. Small increases in δ13C at -112 cm (4300 calibrated years BP) and -85 cm (3800 calibrated years BP) may reflect C dynamics during a suspected transitional fen stage (based on paleoecology at a nearby bog), when reduced methanotrophy retained less 13C-depleted carbon derived from methane than in later periods. The C/N decreased until about -85 cm and thereafter remained steady, suggesting that the active zone of aerobic processing during drought may extend to this depth. The inflection point in calculated carbon accumulation rates at this depth supports this conclusion.

  9. Autotrophic growth of nitrifying community in an agricultural soil

    PubMed Central

    Xia, Weiwei; Zhang, Caixia; Zeng, Xiaowei; Feng, Youzhi; Weng, Jiahua; Lin, Xiangui; Zhu, Jianguo; Xiong, Zhengqin; Xu, Jian; Cai, Zucong; Jia, Zhongjun

    2011-01-01

    The two-step nitrification process is an integral part of the global nitrogen cycle, and it is accomplished by distinctly different nitrifiers. By combining DNA-based stable isotope probing (SIP) and high-throughput pyrosequencing, we present the molecular evidence for autotrophic growth of ammonia-oxidizing bacteria (AOB), ammonia-oxidizing archaea (AOA) and nitrite-oxidizing bacteria (NOB) in agricultural soil upon ammonium fertilization. Time-course incubation of SIP microcosms indicated that the amoA genes of AOB was increasingly labeled by 13CO2 after incubation for 3, 7 and 28 days during active nitrification, whereas labeling of the AOA amoA gene was detected to a much lesser extent only after a 28-day incubation. Phylogenetic analysis of the 13C-labeled amoA and 16S rRNA genes revealed that the Nitrosospira cluster 3-like sequences dominate the active AOB community and that active AOA is affiliated with the moderately thermophilic Nitrososphaera gargensis from a hot spring. The higher relative frequency of Nitrospira-like NOB in the 13C-labeled DNA suggests that it may be more actively involved in nitrite oxidation than Nitrobacter-like NOB. Furthermore, the acetylene inhibition technique showed that 13CO2 assimilation by AOB, AOA and NOB occurs only when ammonia oxidation is not blocked, which provides strong hints for the chemolithoautotrophy of nitrifying community in complex soil environments. These results show that the microbial community of AOB and NOB dominates the nitrification process in the agricultural soil tested. PMID:21326337

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

    NASA Astrophysics Data System (ADS)

    Walters, W.; Michalski, G. M.

    2013-12-01

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

  11. Calibrating compound-specific stable nitrogen isotope analysis in avian eggs as bioarchives for paleoreconstruction

    NASA Astrophysics Data System (ADS)

    Preciado, C., Jr.

    2016-12-01

    Compound-specific stable isotope analysis (CSIA) has become a powerful tool for reconstructing consumer-resource relationships in modern and ancient systems. Stable nitrogen isotope analysis (δ15N) of "trophic" and "source" amino acids provides independent proxies of trophic position and the δ15N value at the base of the food web, respectively. When applied to avian egg tissues (e.g., shell protein, membrane), which can be preserved in the archaeological record, this approach can be used to address complex questions in food web architecture and biogeochemical cycling. In this study, we examined how sample-processing protocols affected the chromatography and reliability of δ15N values of individual amino acids in avian (chicken and penguin) egg components (shell protein, membrane, yolk, and albumen) via gas chromatography-combustion-isotope ratio mass spectrometry. "Unprocessed" egg tissues underwent standard acid hydrolysis protocols prior to derivatization, and resulted in poor chromatography with highly variable δ15N values across replicates. "Processed" samples were eluted through cation exchange columns (Dowex 50WX*400) prior to derivatization, followed by a P-buffer (KH2PO4 + Na2HPO4)-chloroform centrifugation extraction to remove confounding peaks and matrix impurities. These additional procedures greatly improved the chromatography of the "processed" samples, revealing better peak separation and baseline integration as well as lower δ15N variability. Additionally, a standard lipid extraction was necessary for yolk but not membrane, albumen, and shell. While the additional procedures applied to the "columned" samples did result in a significant reduction in sample yield ( 20%), it was non-fractionating and thus only affected the total sample sizes necessary for δ15N CSIA (shell protein 50mg and membrane, yolk, and albumen 0.5mg). The protocols developed here will streamline CSIA of egg tissues for future work in avian ecology.

  12. Microbial community analysis in the autotrophic denitrification process using spent sulfidic caustic by denaturing gradient gel electrophoresis of PCR-amplified genes.

    PubMed

    Lee, J-H; Lee, S-M; Choi, G-C; Park, H-S; Kang, D-H; Park, J-J

    2011-01-01

    Spent sulfidic caustic (SSC) produced from petrochemical plants contains a high concentration of hydrogen sulfide and alkalinity, and some almost non-biodegradable organic compounds such as benzene, toluene, ethylbenzene and xylenes (BTEX). SSC is mainly incinerated with auxiliary fuel, leading to secondary pollution problems. The reuse of this waste is becoming increasingly important from economic and environmental viewpoints. To denitrify wastewater with low COD/N ratio, additional carbon sources are required. Thus, autotrophic denitrification has attracted increasing attention. In this study, SSC was injected as an electron donor for sulfur-based autotrophic denitrification in the modified Ludzack-Ettinger (MLE) process. The efficiencies of nitrification, COD, and total nitrogen (TN) removal were evaluated with varying SSC dosage. Adequate SSC injection exhibited stable autotrophic denitrification. No BTEX were detected in the monitored BTEX concentrations of the effluent. To analyse the microbial community of the MLE process, PCR-DGGE based on 16 S rDNA with EUB primers, TD primers and nirK gene with nirK primers was performed in order to elucidate the application of the MLE process to SSC.

  13. Carbon and Nitrogen Stable Isotopes in Fastfood: Signatures of Corn and Confinement

    NASA Astrophysics Data System (ADS)

    Jahren, H.; Kraft, R.

    2008-12-01

    Americans spend more than one hundred billion dollars on restaurant fastfood each year; fastfood meals comprise a disproportionate amount of both meat and calories within the U.S. diet. Frustrated by futile attempts to gain information about the origin and production of fastfood from the companies themselves, we used carbon and nitrogen stable isotopes to infer the source of feed to meat animals, the source of fat within fries, and the extent of fertilization and confinement inherent to production. We sampled food from McDonald's, Burger King and Wendy's chains, purchasing more than 480 servings of hamburgers, chicken sandwiches and fries within geographically-distributed U.S. cities: Los Angeles, San Francisco, Denver, Detroit, Boston and Baltimore. From the entire sample set of beef and chicken, only 12 servings of beef had δ13C < -21 ‰; for these animals only was a food source other than corn possible. We observed remarkably invariant values of δ15N in both beef and chicken, reflecting uniform confinement and exposure to heavily fertilized feed for all animals. The δ13C value of fries differed significantly among restaurants indicating that the chains employed different protocols for deep- frying: Wendy's clearly employed only corn oil, while McDonald's and Burger King favored other vegetable oils; this differed from ingredient reports. Our results highlighted the overwhelming importance of corn agriculture within virtually every aspect of fastfood manufacture.

  14. Using nitrogen stable isotopes to detect longdistance movement in a threatened cutthroat trout (Oncorhynchus clarkii utah)

    USGS Publications Warehouse

    Sepulveda, A.J.; Colyer, W.T.; Lowe, W.H.; Vinson, M.R.

    2009-01-01

    Interior cutthroat trout occupy small fractions of their historic ranges and existing populations often are relegated to headwater habitats. Conservation requires balancing protection for isolated genetically pure populations with restoration of migratory life histories by reconnecting corridors between headwater and mainstem habitats. Identification of alternative life history strategies within a population is critical to these efforts. We tested the application of nitrogen stable isotopes to discern fluvial from resident Bonneville cutthroat trout (BCT; Oncorhynchus clarkii utah) in a headwater stream. Fluvial BCT migrate from headwater streams with good water quality to mainstem habitats with impaired water quality. Resident BCT remain in headwater streams. We tested two predictions: (i) fluvial BCT have a higher ??15N than residents, and (ii) fluvial BCT ??15N reflects diet and ??15N enrichment characteristics of mainstem habitats. We found that fluvial ??15N was greater than resident ??15N and that ??15N was a better predictor of life history than fish size. Our data also showed that fluvial and resident BCT had high diet overlap in headwater sites and that ??15N of lower trophic levels was greater in mainstem sites than in headwater sites. We conclude that the high ??15N values of fluvial BCT were acquired in mainstem sites.

  15. Population and individual foraging patterns of two hammerhead sharks using carbon and nitrogen stable isotopes.

    PubMed

    Loor-Andrade, P; Galván-Magaña, F; Elorriaga-Verplancken, F R; Polo-Silva, C; Delgado-Huertas, A

    2015-05-15

    Individual foraging behavior is an important variable of predators commonly studied at the population level. Some hammerhead shark species play a significant role in the marine ecosystem as top consumers. In this context, stable isotope analysis allows us to infer some ecological metrics and patterns that cannot usually be obtained using traditional methods. We determined the isotopic composition (δ(13)C and δ(15)N values) of dorsal muscle and vertebrae of Sphyrna lewini and Sphyrna zygaena using a continuous-flow system consisting of an elemental analyzer combined with a Delta Plus XL mass spectrometer. Foraging variability by sex and by individual was inferred from the isotopic values. There were no significant differences in the isotopic values of muscle samples between sexes, but there were differences between species. The trophic niche breadth of the two species was similar and overlap was low. A low niche overlap was observed between S. lewini individual vertebrae. We found differences in the δ(15)N values of S. zygaena vertebrae, with lower values in the first group of samples. Despite these hammerhead shark species inhabiting the same area, there was low trophic niche overlap between species and individuals, due to different individual foraging strategies, according to the carbon and nitrogen isotopic profiles obtained. The use of tissues that retain lifetime isotopic information is useful to complement studies on trophic ecology. Copyright © 2015 John Wiley & Sons, Ltd.

  16. Evaluating larval mosquito resource partitioning in western Kenya using stable isotopes of carbon and nitrogen

    PubMed Central

    2013-01-01

    Background In sub-Saharan Africa, malaria, transmitted by the Anopheles mosquito, remains one of the foremost public health concerns. Anopheles gambiae, the primary malaria vector in sub-Saharan Africa, is typically associated with ephemeral, sunlit habitats; however, An. gambiae larvae often share these habitats with other anophelines along with other disease-transmitting and benign mosquito species. Resource limitations within habitats can constrain larval density and development, and this drives competitive interactions among and between species. Methods We used naturally occurring stable isotope ratios of carbon and nitrogen to identify resource partitioning among co-occurring larval species in microcosms and natural habitats in western Kenya. We used two and three source mixing models to estimate resource utilization (i.e. bacteria, algae, organic matter) by larvae. Results Laboratory experiments revealed larval δ13C and δ15N composition to reflect the food sources they were reared on. Resource partitioning was demonstrated between An. gambiae and Culex quinquefasciatus larvae sharing the same microcosms. Differences in larval δ13C and δ15N content was also evident in natural habitats, and Anopheles species were consistently more enriched in δ13C when compared to culicine larvae. Conclusions These observations demonstrate inter-specific resource partitioning between Cx. quinquefasciatus and An. gambiae larvae in natural habitats in western Kenya. This information may be translated into opportunities for targeted larval control efforts by limiting specific larval food resources, or through bio-control utilizing competitors at the same trophic level. PMID:24330747

  17. Nitrogen stable isotopes reveal age-dependent dietary shift in the Japanese scallop Mizuhopecten yessoensis.

    PubMed

    Aya, Frolan A; Kudo, Isao

    2017-03-01

    Ontogenetic niche shifts in diet are a consequence of changes in body size or resource partitioning between age classes. To better resolve the feeding patterns of the Japanese scallop Mizuhopecten yessoensis, we examined the relative importance of age and size in the diet of this species using stable isotope ratios of carbon (δ(13)C) and nitrogen (δ(15)N) from 2006 to 2009. Contribution of food sources was quantified using an isotope mixing model by comparing the muscle tissue isotope ratios to those of suspended particulate organic matter (SPOM) and their zooplankton prey (e.g. micro- and meso-zooplankton). Unlike the δ(13)C values, which remained constant with age and size, muscle δ(15)N values were more positively correlated with age accounting for 69 % of variations than size with only 46 %. Increasing (15)N values with age suggested that shifts in diet from SPOM to micro- and meso-zooplankton occurred during ontogeny in M. yessoensis. Results of the isotope mixing model indicated that SPOM contribution to scallop's diet decreased from 68 to 8 % while those of zooplankton increased from 15 to 50 % with increasing age. This study concludes that age-related dietary shift explains the enrichment of (15)N, as a result of predation on zooplankton by M. yessoensis.

  18. Stable isotopes of nitrogen in plants of contaminated soils and sediments by an abandoned gold mine

    NASA Astrophysics Data System (ADS)

    Becerra, O. F.; Sanchez, A.; Marmolejo, A. J.; Magallanes, V. R.

    2013-05-01

    Mining industry is an economic activity which generates high ecological impact. In the mining district "El Triunfo", the concentration of potential toxic elements (PTE: As, Cd, Hg, Sb) have exceeded 50 times allowable limits. Nowadays, environmental pollution levels can be evaluated through the use of stable isotopes of N. For this, isotopic analysis of nitrogen and concentrations of metals and metalloids were considered in the area where plants are exposed (Prosopis spp., Parkinsonia spp. and Salicornia spp.) Polluted sediments were collected over 48 km of the Las Gallinas-El Hondo-El Carrizal arroyo. PTE concentrations, with a previous acidic digestion (HF, HCl, HNO3 and H2SO4) were determined by ICP-MS. As and Sb were determined by NAA. For N isotopes, obtained samples were grounded to fine powder in an agate mortar with an acetone rinse between samples then analyzed by an EA-IRMS. Results showed that plants growing on the tailings decreased their δ15N proportionally to the metal concentration in the area.

  19. Carbon and nitrogen stable isotopes in fast food: Signatures of corn and confinement

    PubMed Central

    Jahren, A. Hope; Kraft, Rebecca A.

    2008-01-01

    Americans spend >100 billion dollars on restaurant fast food each year; fast food meals comprise a disproportionate amount of both meat and calories within the U.S. diet. We used carbon and nitrogen stable isotopes to infer the source of feed to meat animals, the source of fat within fries, and the extent of fertilization and confinement inherent to production. We sampled food from McDonald's, Burger King, and Wendy's chains, purchasing >480 servings of hamburgers, chicken sandwiches and fries within geographically distributed U.S. cities: Los Angeles, San Francisco, Denver, Detroit, Boston, and Baltimore. From the entire sample set of beef and chicken, only 12 servings of beef had δ13C < −21‰; for these animals only was a food source other than corn possible. We observed remarkably invariant values of δ15N in both beef and chicken, reflecting uniform confinement and exposure to heavily fertilized feed for all animals. The δ13C value of fries differed significantly among restaurants indicating that the chains used different protocols for deep-frying: Wendy's clearly used only corn oil, whereas McDonald's and Burger King favored other vegetable oils; this differed from ingredient reports. Our results highlighted the overwhelming importance of corn agriculture within virtually every aspect of fast food manufacture. PMID:19001276

  20. Nitrogen stable isotope composition (δ15N) of vehicle-emitted NOx.

    PubMed

    Walters, Wendell W; Goodwin, Stanford R; Michalski, Greg

    2015-02-17

    The nitrogen stable isotope ratio of NOx (δ(15)N-NOx) has been proposed as a regional indicator for NOx source partitioning; however, knowledge of δ(15)N values from various NOx emission sources is limited. This study presents a detailed analysis of δ(15)N-NOx emitted from vehicle exhaust, the largest source of anthropogenic NOx. To accomplish this, NOx was collected from 26 different vehicles, including gasoline and diesel-powered engines, using a modification of a NOx collection method used by the United States Environmental Protection Agency, and δ(15)N-NOx was analyzed. The vehicles sampled in this study emitted δ(15)N-NOx values ranging from -19.1 to 9.8‰ that negatively correlated with the emitted NOx concentrations (8.5 to 286 ppm) and vehicle run time because of kinetic isotope fractionation effects associated with the catalytic reduction of NOx. A model for determining the mass-weighted δ(15)N-NOx from vehicle exhaust was constructed on the basis of average commute times, and the model estimates an average value of -2.5 ± 1.5‰, with slight regional variations. As technology improvements in catalytic converters reduce cold-start emissions in the future, it is likely to increase current δ(15)N-NOx values emitted from vehicles.

  1. Stable nitrogen isotope ratios and accumulation of various HOCs in northern Baltic aquatic food chains

    SciTech Connect

    Broman, D.; Axelman, J.; Bergqvist, P.A.; Naef, C.; Rolff, C.; Zebuehr, Y.

    1995-12-31

    Ratios of naturally occurring stable isotopes of nitrogen ({delta}{sup 15}N) can be used to numerically classify trophic levels of organisms in food chains. By combining analyses results of various HOCs (e.g. PCDD/Fs, PCBs, DDTs, HCHs and some other pesticides) the biomagnification of these substances can be quantitatively estimated. In this paper different pelagic and benthic northern Baltic food chains were studied. The {delta}{sup 15}N-data gave food chain descriptions qualitatively consistent with previous conceptions of trophic arrangements in the food chains. The different HOCs concentrations were plotted versus the {delta}{sup 15}N-values for the different trophic levels and an exponential model of the form e{sup (A+B*{delta}N)} was fitted to the data. The estimates of the constant B in the model allows for an estimation of a biomagnification power (B) of different singular, or groups of, contaminants. A B-value around zero indicates that a substance is flowing through the food chain without being magnified, whereas a value > 0 indicates that a substance is biomagnified. Negative B-values indicate that a substance is not taken up or is metabolized. The A-term of the expression is only a scaling factor depending on the background level of the contaminant.

  2. Source apportionment of ammonium and nitrate ion using nitrogen stable isotope

    NASA Astrophysics Data System (ADS)

    Kawashima, H.

    2013-12-01

    Suspended particulate matter (SPM), defined to particle size as 100 % cut-off aerodynamic diameter at 10 μm, has adverse effects on human health. In these years, stable isotope ratio of small sample volume can be analyzed high precision by isotope ratio mass spectrometry coupling with elemental analyzer. Recently some fields are using stable isotope ratio. For environmental field, it is expected such as powerful tool for source identification and understanding mechanism. But the existed researches intended for stable nitrogen isotope (δ15N) of particulate matter have been limited. We try to analysis δ15N-ammonium (δ15N-NH4+) and nitrate (δ15N-NO3-) of SPM, to estimate source of NH4+ and NO3- of SPM. Average δ15N-NH4+ and δ15N-NO3- of SPM in Akita prefecture, Japan were 15.9 ‰ (1.3‰ to 38.5 ‰) and - 0.7 ‰ (-4.6 ‰ to 4.8 ‰), respectively. Although δ15N-NH4+ do not show seasonal trend, δ15N-NO3- increased in winter markedly and decreasing in summer. In generally, the dominant origin of NO3- of SPM is produced from NOx emitted by combustion of some fuel and NO by agriculture source. Heaton (1990) summarized that δ15N-NOx is very different by temperature of combustion. They insisted that δ15N-NOx values are between -13 ‰ to -2 ‰ over 2000 °C (e.g. vehicle engine) and 6 ‰ to 13 ‰ under 1300 °C (e.g. coal combustion). Therefore, the reason of the winter high trend in this study might be combustion process such as coal combustion source. Moreover, the baseline might be made by vehicle sources. In addition, the reason of decreasing in summer seemed to be affected very low δ15N-NO of fertilizer and urea indicated by Li and Wang (2008). Bacteria were activated in summer, and NO from fertilizer and urea was emitted. This summary seemed to be very reasonable.

  3. Nitrogen Limitation Along The Kalahari Transect: Preliminary Results From A Stable Isotope Fertilization Experiment

    NASA Astrophysics Data System (ADS)

    Wang, L.; Macko, S.; D'Odorico, P.; Ries, L.

    2005-12-01

    Globally, savannas cover ~ 20% of the Earth's land area. Nutrients and soil moisture interactively control vegetation dynamics in many savannas although it is unclear how the relative importance of water and nutrient limitations (especially nitrogen) change with the mean climatic conditions. The Kalahari Transect (KT) in southern Africa traverses a dramatic aridity gradient (from ~ 200 mm to more than 1000 mm of mean annual precipitation (MAP), through the Republic of South Africa, Botswana, Namibia and Zambia), on relatively homogenous soils (deep Kalahari sands). This transect offers the ideal setting to study nutrient and vegetation dynamics without confounding soil effects. To improve the understanding of nitrogen and water controls on savanna vegetation, this study tested the hypothesis that the savannas in the Kalahari switch from conditions of water limitation in the dry areas to nutrient limitation in the wet areas. To this end, we conducted a large-scale stable isotope fertilization experiment using four study sites with different MAP. The transect included sites in Mongu, Zambia (MAP ~950mm), Pandamatenga, Ghanzi, and Tshane, Botswana with MAP ranging between 700 mm and 300 mm. The experimental design consisted of a randomized block design with four 21 m x 13 m plots at each site. Each plot was divided into four 10 m x 6 m subplots with 1 m buffer zone between each subplot. Four treatments (N addition, P addition, N+P addition and control) were randomly applied to the subplots. The experiment began during the dry season, in August, 2004, when 39g/m2 of Ca(NO3)2 (3.3g-N/ m2 ) was evenly applied to the N and N+P subplots, and 7.5g/m2 of Ca(H2PO4)2 (1.7g-P/m2) was applied to the P and N+P subplots, while the control subplots were left with no treatment. The N and N+P additions were enriched with 15N (Ca(15NO3)2 ) to a signature of 10.3 ‰. Before application, soil samples from two different layers (0cm and 50cm) outside the plots and foliar samples of the

  4. Granulation of sulfur-oxidizing bacteria for autotrophic denitrification.

    PubMed

    Yang, Weiming; Lu, Hui; Khanal, Samir K; Zhao, Qing; Meng, Liao; Chen, Guang-Hao

    2016-11-01

    Sulfur-oxidizing bacteria (SOB) was successfully employed for effective autotrophic denitrification and sludge minimization in a full-scale application of saline sewage treatment in Hong Kong. In this study, a Granular Sludge Autotrophic Denitrification (GSAD) reactor was continuously operated over 600 days for SOB granulation, and to evaluate the long-term stability of SOB granules, microbial communities and denitrification efficacy. Sludge granulation initiated within the first 40 days of start-up with an average particle size of 186.4 μm and sludge volume index (SVI5) of 40 mL/g in 5 min. The sludge granules continued to grow reaching a nearly uniform size of mean diameter 1380 ± 20 μm with SVI5 of 30 mL/g during 600 days of GSAD reactor operation at hydraulic retention time of 5 h and nitrate loading rate of 0.33 kg-N/m(3)/d. The GSAD reactor with SOB granular sludge achieved 93.7 ± 2.1% nitrogen and complete sulfide removal with low sludge yield of 0.15 g-volatile suspended solids (VSS)/g-N, and much lower nitrous oxide (N2O) emission than the heterotrophic denitrifying process. Microbial community analysis using fluorescence in situ hybridization (FISH) technique revealed that granules were enriched with SOB contributing to autotrophic denitrification. Furthermore, 16S rRNA analysis showed diverse autotrophic denitrification related genera, namely Thiobacillus (32.6%), Sulfurimonas (31.3%), and Arcobacter (0.01%), accounting for 63.9% of total operational taxonomic units at the generic level. No heterotrophic denitrification related genera were detected. The results from this study could provide useful design and operating conditions with respect to SOB sludge granulation and its subsequent application in a full-scale autotrophic denitrification in the Sulfate reduction-Autotrophic denitrification-Nitrification Integrated (SANI) process. Copyright © 2016 Elsevier Ltd. All rights reserved.

  5. Assessment of effects of the rising atmospheric nitrogen deposition on nitrogen uptake and long-term water-use efficiency of plants using nitrogen and carbon stable isotopes.

    PubMed

    Yao, F Y; Wang, G A; Liu, X J; Song, L

    2011-07-15

    This study assesses the effects of the atmospheric nitrogen (N) deposition on the N uptake and the long-term water-use efficiency of two C(3) plants (Agropyron cristatum and Leymus chinensis) and two C(4) plants (Amaranthus retroflexus and Setaria viridis) using N and C stable isotopes. In addition, this study explores the potential correlation between leaf N isotope (δ(15)N) values and leaf C isotope (δ(13)C) values. This experiment shows that the atmospheric N deposition has significant effects on the N uptake, δ(15)N and leaf N content (N(m)) of C(3) plants. As the atmospheric N deposition rises, the proportion and the amount of N absorbed from the simulated atmospheric deposition become higher, and the δ(15)N and N(m) of the two C(3) plants both also increase, suggesting that the rising atmospheric N deposition is beneficial for C(3) plants. However, C(4) plants display different patterns in their N uptake and in their variations of δ(15)N and N(m) from those of C(3) plants. C(4) plants absorb less N from the atmospheric deposition, and the leaf N(m) does not change with the elevated atmospheric N deposition. Photosynthetic pathways may account for the differences between C(3) and C(4) plants. This study also shows that atmospheric N deposition does not play a role in determining the δ(13)C and in the long-term water-use efficiency of C(3) and C(4) plants, suggesting that the long-term water-use pattern of the plants does not change with the atmospheric N input. In addition, this study does not observe any relationship between leaf δ(15)N and leaf δ(13)C in both C(3) and C(4) plants.

  6. Molecular Ecological and Stable Isotopic Studies of Nitrogen Fixation in Modern Microbial Mats

    NASA Technical Reports Server (NTRS)

    Bebout, B. M.; Crumbliss, L. L.; DesMarais, D. J.; Hogan, M. E.; Omoregie, E.; Turk, K. A.; Zehr, J. P.

    2003-01-01

    Nitrogen is usually the element limiting biological productivity in the marine environment. Microbial mats, laminated microbial communities analogous to some of the oldest forms of life on Earth, are often the sites of high rates of N fixation (the energetically expensive conversion of atmospheric dinitrogen into a biologically useful form). The N fixing enzyme nitrogenase is generally considered to be of ancient origin, and is widely distributed throughout the Bacterial and Archaeal domains of life, indicating an important role for this process over evolutionary time. The stable isotopic signature of N fixation is purportedly recognizable in organic matter (ancient kerogens as well as present-day microbial mats) as a delta (15)N(sub organic) near zero. We studied two microbial mats exhibiting different rates of N fixation in order to better understand the impact of N fixation on the delta (15)N (sub organic) of the mats, as well as what organisms are important in this process. Mats dominated by the cyanobacterium Microcoleus chthonoplastes grow in permanently submerged hypersaline salterns, and exhibit low rates of N fixation, whereas mats dominated by the cyanobacterium Lyngbya spp grow in an intertidal area, and exhibit rates of N fixation an order of magnitude higher. To examine successional stages in mat growth, both developing and established mats at each location were sampled. PCR and RT-PCR based approaches were used to identify, respectively, the organisms containing nifH (one of the genes that encode nitrogenase) as well as those expressing nifH in these mats. Both mats exhibited a distinct diel cycle of N fixation, with highest rates occurring at night. The delta (15)N(sub organic) of the subtidal Microcoleus mats is near zero whereas the delta (15)N(sub organic) is slightly more positive (+ 2-3%), in the intertidal Lyngbya mats, an interesting difference in view of the fact that overall rates of activity in the intertidal mats are much higher that those

  7. Stable carbon, nitrogen and sulfur isotopes in non-carbonate fractions of cold-seep carbonates

    NASA Astrophysics Data System (ADS)

    Feng, Dong; Peng, Yongbo; Peckmann, Jörn; Roberts, Harry; Chen, Duofu

    2017-04-01

    Sulfate-driven anaerobic oxidation of methane (AOM) supports chemosynthesis-based communities and limits the release of methane from marine sediments. This process promotes the formation of carbonates close to the seafloor along continental margins. The geochemical characteristics of the carbonate minerals of these rocks are increasingly understood, questions remain about the geochemical characteristics of the non-carbonate fractions. Here, we report stable carbon, nitrogen and sulfur isotope patterns in non-carbonate fractions of seep carbonates. The authigenic carbonates were collected from three modern seep provinces (Black Sea, Gulf of Mexico, and South China Sea) and three ancient seep deposits (Marmorito, northern Italy, Miocene; SR4 deposit of the Lincoln Creek Formation and Whiskey Creek, western Washington, USA, Eocene to Oligocene). The δ13C values of non-carbonate fractions range from ˜-25‰ to -80‰ VPDB. These values indicate that fossil methane mixed with varying amounts of pelagic organic matter is the dominant source of carbon in these fractions. The relatively small offset between the δ34S signatures of the non-carbonate fractions and the respective sulfide minerals suggests that locally produced hydrogen sulfide is the main source of sulfur in seep environments. The δ15N values of the non-carbonate fractions are generally lower than the corresponding values of deep-sea sediments, suggesting that organic nitrogen is mostly of a local origin. This study reveals the potential of using δ13C, δ15N, δ34S values to discern seep and non-seep deposits. In cases where δ13Ccarbonate values are only moderately low due to mixing processes and lipid biomarkers have been erased in the course of burial, it is difficult to trace back AOM owing to the lack of other records. This problem is even more pronounced when authigenic carbonate is not available in ancient seep environments. Acknowledgments: The authors thank BOEM and NOAA for their years' support

  8. Organic Stable Isotopes in Ancient Oyster Shell Trace Pre-colonial Nitrogen Sources

    NASA Astrophysics Data System (ADS)

    Darrow, E. S.; Carmichael, R. H.; Andrus, C. F. T.; Jackson, H. E.

    2016-02-01

    Oysters (Crassostrea virginica) were an important food resource for native peoples of the northern Gulf of Mexico, who harvested oysters and deposited waste shell and other artifacts in middens. Shell δ15N is a proxy for oyster tissue δ15N that reflects nitrogen (N) in food sources of bivalves. We tested the use of shell δ15N as a paleo proxy of ancient N sources, which to our knowledge has not been previously done for archeological bivalve specimens. To determine δ15N of the very low-N and high-carbonate ancient specimens, we tested established and modified acidification techniques developed for modern clams and oysters to decalcify organic shell matrix and extract sufficient N for analyses. Centrifugation following acidification better concentrated N from ancient shells for stable isotope analysis. Careful screening was required to detect effects of diagenesis, incomplete acidification, and sample contamination. Modern oyster shells did not require acidification and bulk shell material was directly analyzed for δ15N using an EA-IRMS coupled to a CO2 trap. δ15N values in ancient oyster shells did not differ from modern oyster shells from the same sites, but %N and % organic carbon (C) were lower in ancient than in modern shells. Organic δ13C in ancient shells had a significant negative relationship with shell age, possibly due to an effect of sea level rise increasing marine suspended particulate matter (SPM) sources to oysters. In modern oysters, δ15N had a significant relationship with soft tissue δ15N, and predicted by SPM δ15N, water column nitrate, and water column dissolved organic nitrogen (DON) concentrations, demonstrating the effectiveness of oyster shell δ15N to identify N sources to bivalves such as oysters. Our study has demonstrated the usefulness of δ15N from midden oyster shells as a proxy for N sources in an estuary that has undergone relatively light impacts from human land-use change through the past 2000 years.

  9. Investigation of mixotrophic, heterotrophic, and autotrophic growth of Chlorella vulgaris under agricultural waste medium.

    PubMed

    Mohammad Mirzaie, M A; Kalbasi, M; Mousavi, S M; Ghobadian, B

    2016-01-01

    Growth of Chlorella vulgaris and its lipid production were investigated under autotrophic, heterotrophic, and mixotrophic conditions. Cheap agricultural waste molasses and corn steep liquor from industries were used as carbon and nitrogen sources, respectively. Chlorella vulgaris grew remarkably under this agricultural waste medium, which resulted in a reduction in the final cost of the biodiesel production. Maximum dry weight of 2.62 g L(-1) was obtained in mixotrophic growth with the highest lipid concentration of 0.86 g L(-1). These biomass and lipid concentrations were, respectively, 140% and 170% higher than autotrophic growth and 300% and 1200% higher than heterotrophic growth. In mixotrophic growth, independent or simultaneous occurrence of autotrophic and heterotrophic metabolisms was investigated. The growth of the microalgae was observed to take place first heterotrophically to a minimum substrate concentration with a little fraction in growth under autotrophic metabolism, and then the cells grew more autotrophically. It was found that mixotrophic growth was not a simple combination of heterotrophic and autotrophic growth.

  10. Stable carbon and nitrogen isotope composition of aquatic and terrestrial plants of the San Francisco Bay estuarine system

    USGS Publications Warehouse

    Cloern, J.E.; Canuel, E.A.; Harris, D.

    2002-01-01

    We report measurements of seasonal variability in the C-N stable isotope ratios of plants collected across the habitat mosaic of San Francisco Bay, its marshes, and its tributary river system. Analyses of 868 plant samples were binned into 10 groups (e.g., terrestrial riparian, freshwater phytoplankton, salt marsh) to determine whether C-N isotopes can be used as biomarkers for tracing the origins of organic matter in this river-marsh-estuary complex. Variability of ??13C and ??15N was high (???5-10???) within each plant group, and we identified three modes of variability: (1) between species and their microhabitats, (2) over annual cycles of plant growth and senescence, and (3) between living and decomposing biomass. These modes of within-group variability obscure any source-specific isotopic signatures, confounding the application of C-N isotopes for identifying the origins of organic matter. A second confounding factor was large dissimilarity between the ??13C-??15N of primary producers and the organic-matter pools in the seston and sediments. Both confounding factors impede the application of C-N isotopes to reveal the food supply to primary consumers in ecosystems supporting diverse autotrophs and where the isotopic composition of organic matter has been transformed and become distinct from that of its parent plant sources. Our results support the advice of others: variability of C-N stable isotopes within all organic-matter pools is high and must be considered in applications of these isotopes to trace trophic linkages from primary producers to primary consumers. Isotope-based approaches are perhaps most powerful when used to complement other tools, such as molecular biomarkers, bioassays, direct measures of production, and compilations of organic-matter budgets.

  11. Assessment of trophic structure of Cretaceous communities based on stable nitrogen isotope analyses

    NASA Astrophysics Data System (ADS)

    Ostrom, P. H.; Macko, S. A.; Engel, M. H.; Russell, D. A.

    1993-06-01

    New δ15N data suggest the retention of an indigenous signal in ancient high molecular weight organic material. These data open the possibility of obtaining new paleoecological information, based on isotopic analyses, on ancient, well-preserved fossil communities. Stable carbon and nitrogen isotope analyses were performed on high molecular weight organic material isolated from 22 taxa of Late Cretaceous vertebrates (Judith River Formation, Alberta,Canada). The majority of δ13C and δ15N values (-27‰ to -23‰ and 4‰ to 12‰, for δ13C and δ15N, respectively) are similar to those reported for modern consumers. An assessment of trophic levels based on δ15N is consistent with previous interpretations of food web structure derived from paleoecological interpretations. Among terrestrial consumers, carnivorous theropods (tyrannosaurids and dromaeosaurids) have high δ15N values (6.6‰ ±0.4‰ and 7.9‰, respectively) relative to those of the dominant megaherbivore (hadrosaurids, 4.7‰ ±0.5‰). Within aquatic environments, the values of δ15N of the bowfin Amia (11.6‰) and plesiosaur (11.0‰),distinguish the piscivorous tendencies of these organisms from those of tower trophic level consumers such as the benthic feeding sturgeon Acipenser and the turtle Aspideretes (δ15N = 5.1‰ and 4.5‰, respectively). The correlation in trophic position between δ15N values and paleoecological evidence is unlikely to be coincidental.

  12. Stable Isotopes Indicate Nitrogen Sources in Pinguicula vulgaris Across Contrasting Habitat Types in Sub-Arctic Sweden

    NASA Astrophysics Data System (ADS)

    Ackerman, D.; Hobbie, E. A.; Varner, R. K.; Steele, K.

    2012-12-01

    Like most carnivorous plant species, Pinguicula vulgaris (common butterwort) obtains nitrogen from both soil pools and insect prey. Prior studies have estimated percent prey-derived nitrogen (%PDN) for the entire plant, but it may be expected that %PDN varies between plant parts. By measuring stable isotopic ratios in the soil, plants, and naturally captured prey, this study estimated %PDN in both foliage and roots. Plants, soil and insects were collected during July 2012 in sub-arctic Sweden across two habitat types: dry heath and moist sphagnum. Insect samples were homogenized for each site, and all samples were cleaned, dried, and measured for δ15N in an isotope ratio mass spectrometer. Roots showed consistent %PDN in both habitat types, whereas foliage in moist sphagnum sites had significantly greater %PDN than foliage in dry heath sites. Amount of captured prey did not differ significantly between habitat types. These results provide the framework for a rough model of the differential distribution of prey- and soil-derived nitrogen in P. vulgaris, where root nitrogen is split approximately evenly between the two sources, and foliar nitrogen varies by site, possibly dependent on the accessibility of nitrogen in the soil pool.

  13. Use of stable isotopes of nitrogen and water to identify sources of nitrogen in three urban creeks of Durham, North Carolina, 2011-12

    USGS Publications Warehouse

    McSwain, Kristen Bukowski; Young, Megan B.; Giorgino, Mary L.

    2014-01-01

    A preliminary assessment of nitrate sources was conducted in three creeks that feed nutrient impaired Falls and Jordan Lakes in the vicinity of Durham County, North Carolina, from July 2011 to June 2012. Cabin Branch, Ellerbe Creek, and Third Fork Creek were sampled monthly to determine if sources of nitrate in surface water could be identified on the basis of their stable isotopic compositions. Land use differs in the drainage basins of the investigated creeks—the predominant land use in Cabin Branch Basin is forest, and the Ellerbe and Third Fork Creek Basins are predominantly developed urban areas. Total nutrient concentrations were below 1 milligram per liter (mg/L). All measured nitrate plus nitrite concentrations were below the North Carolina standard of 10 mg/L as nitrogen with the highest concentration of 0.363 mg/L measured in Third Fork Creek. Concentrations of ammonia were generally less than 0.1 mg/L as nitrogen in all creek samples. More than 50 percent of the total nitrogen measured in the creeks was in the form of organic nitrogen. Total phosphorus and orthophosphate concentrations in all samples were generally less than 0.2 mg/L as phosphorus. The isotopic composition of surface water (δ2HH20 and δ18OH2O) is similar to that of modern-day precipitation. During July and August 2011 and May and June 2012, surface-water samples displayed a seasonal difference in isotopic composition, indicating fractionation of isotopes as a result of evaporation and, potentially, mixing with local and regional groundwater. The dominant source of nitrate to Cabin Branch, Ellerbe Creek, and Third Fork Creek was the nitrification of soil nitrogen. Two stormflow samples in Ellerbe Creek and Third Fork Creek had nitrate sources that were a mixture of the nitrification of soil nitrogen and an atmospheric source that had bypassed some soil contact through impermeable surfaces within the drainage basin. No influence of a septic or wastewater source was found in Cabin

  14. Fluidization velocity assessment of commercially available sulfur particles for use in autotrophic denitrification biofilters

    USDA-ARS?s Scientific Manuscript database

    There has been no evaluation of sulfur-based autotrophic denitrification using fluidized biofilters in a recirculating aquaculture system to mitigate nitrate-nitrogen loads. The objectives of this work were to quantify the particle size distribution, specific surface area, and fluidization velocitie...

  15. Methyl mercury and stable isotopes of nitrogen reveal that a terrestrial spider has a diet of emergent aquatic insects.

    PubMed

    Speir, Shannon L; Chumchal, Matthew M; Drenner, Ray W; Cocke, W Gary; Lewis, Megan E; Whitt, Holly J

    2014-11-01

    Terrestrial spiders transfer methyl mercury (MeHg) to terrestrial consumers such as birds, but how spiders become contaminated with MeHg is not well understood. In the present study, the authors used stable isotopes of nitrogen in combination with MeHg to determine the source of MeHg to terrestrial long-jawed orb weaver spiders (Tetragnatha sp). The authors collected spiders and a variety of other aquatic and terrestrial taxa from 10 shallow ponds in north Texas, USA. Based on MeHg concentrations and stable nitrogen isotope ratios, the authors identified distinct aquatic- and terrestrial-based food chains. Long-jawed orb weaver spiders belonged to the aquatic-based food chain, indicating that they are exposed to MeHg through their consumption of emergent aquatic insects. Additionally, the present study suggests that ecologists can use stable isotopes of nitrogen (δ(15) N) in conjunction with MeHg speciation analysis to distinguish between aquatic and terrestrial food chains. © 2014 SETAC.

  16. Effect of trans-reservoir water supply on carbon and nitrogen stable isotope composition in hydrologically connected reservoirs in China

    NASA Astrophysics Data System (ADS)

    Zhang, Huajun; Peng, Liang; Gu, Binhe; Han, Bo-Ping

    2017-09-01

    Dajingshan, Fenghuangshan and Meixi reservoirs are located in Zhuhai, a coastal city in southern China, and they function to supply drinking water to Zhuhai and Macau. For effectively supplying waster, they are hydrologically connected and Dajingshan Reservoir first receives the water pumped from the river at Guangchang Pumping Station, and then feeds Fenghuangshan Reservoir, and the two well-connected reservoirs are mesotrophic. Meixi Reservoir is a small and oligotrophic water body and feeds Dajingshan Reservoir only in wet seasons when overflow occurs. Particulate organic matter (POM) was collected from three hydrologically connected water supply reservoirs, and seasonal variations of POM were ascertained from stable carbon and nitrogen isotopes in wet and dry seasons, and the effects of pumping water and reservoir connectivity on POM variations and composition were demonstrated by the relationships of the stable isotope ratios of POM. Seasonality and similarity of stable carbon and nitrogen isotopes of POM varied with hydrodynamics, connectivity and trophic states of the four studied water bodies. The two well-connected reservoirs displayed more similar seasonality for δ13CPOM than those between the river station and the two reservoirs. However, the opposite seasonality appeared for δ15NPOM between the above waters and indicates different processes affecting the stable carbon and nitrogen isotopes of POM. δ13CPOM and δ15NPOM changed little between wet and dry seasons in Meixi Reservoir-a low productive and rain-driven system, suggesting little POM response to environmental changes in that water system. As expected, connectivity enhanced the similarity of the stable isotope ratios of POM between the water bodies.

  17. Effect of trans-reservoir water supply on carbon and nitrogen stable isotope composition in hydrologically connected reservoirs in China

    NASA Astrophysics Data System (ADS)

    Zhang, Huajun; Peng, Liang; Gu, Binhe; Han, Bo-Ping

    2016-10-01

    Dajingshan, Fenghuangshan and Meixi reservoirs are located in Zhuhai, a coastal city in southern China, and they function to supply drinking water to Zhuhai and Macau. For effectively supplying waster, they are hydrologically connected and Dajingshan Reservoir first receives the water pumped from the river at Guangchang Pumping Station, and then feeds Fenghuangshan Reservoir, and the two well-connected reservoirs are mesotrophic. Meixi Reservoir is a small and oligotrophic water body and feeds Dajingshan Reservoir only in wet seasons when overflow occurs. Particulate organic matter (POM) was collected from three hydrologically connected water supply reservoirs, and seasonal variations of POM were ascertained from stable carbon and nitrogen isotopes in wet and dry seasons, and the effects of pumping water and reservoir connectivity on POM variations and composition were demonstrated by the relationships of the stable isotope ratios of POM. Seasonality and similarity of stable carbon and nitrogen isotopes of POM varied with hydrodynamics, connectivity and trophic states of the four studied water bodies. The two well-connected reservoirs displayed more similar seasonality for δ13CPOM than those between the river station and the two reservoirs. However, the opposite seasonality appeared for δ15NPOM between the above waters and indicates different processes affecting the stable carbon and nitrogen isotopes of POM. δ13CPOM and δ15NPOM changed little between wet and dry seasons in Meixi Reservoir-a low productive and rain-driven system, suggesting little POM response to environmental changes in that water system. As expected, connectivity enhanced the similarity of the stable isotope ratios of POM between the water bodies.

  18. Preliminary characterization of nitrogen and phosphorus in groundwater discharging to Lake Spokane, northeastern Washington, using stable nitrogen isotopes

    USGS Publications Warehouse

    Gendaszek, Andrew S.; Cox, Stephen E.; Spanjer, Andrew R.

    2016-02-29

    Lake Spokane, locally referred to as Long Lake, is a 24-mile-long section of the Spokane River impounded by Long Lake Dam that has, in recent decades, experienced water-quality problems associated with eutrophication. Consumption of oxygen by the decomposition of aquatic plants that have proliferated because of high nutrient concentrations has led to seasonally low dissolved oxygen concentrations in the lake. Of nitrogen and phosphorus, the two primary nutrients necessary for aquatic vegetation growth, phosphorus was previously identified as the limiting nutrient that regulates the growth of aquatic plants and, thus, dissolved oxygen concentrations in Lake Spokane. Phosphorus is delivered to Lake Spokane from municipal and industrial point-source inputs to the Spokane River upstream of Lake Spokane, but is also conveyed by groundwater and surface water from nonpoint-sources including septic tanks, agricultural fields, and wildlife. In response, the Washington State Department of Ecology listed Lake Spokane on the 303(d) list of impaired water bodies for low dissolved oxygen concentrations and developed a Total Maximum Daily Load for phosphorus in 1992, which was revised in 2010 because of continuing algal blooms and water-quality concerns.This report evaluates the concentrations of phosphorus and nitrogen in shallow groundwater discharging to Lake Spokane to determine if a difference exists between nutrient concentrations in groundwater discharging to the lake downgradient of residential development with on-site septic systems and downgradient of undeveloped land without on-site septic systems. Elevated nitrogen isotope values (δ15N) within the roots of aquatic vegetation were used as an indicator of septic-system derived nitrogen. δ15N values were measured in August and September 2014 downgradient of residential development near the lakeshore, of residential development on 300-ft-high terraces above the lake, and of undeveloped land in the eastern (upper) and

  19. Investigation into nitrogen attenuation in groundwater pathways in Irish RBDs through the use of stable isotopic signature analysis

    NASA Astrophysics Data System (ADS)

    Orr, Alison; Ofterdinger, Ulrich; Flynn, Raymond

    2010-05-01

    Nitrogen has been identified by the Water Framework Directive as a major pollutant of concern in terms of water quality. Nitrogen contamination can pose a threat to human health and excessive loading into surface waters can lead to eutrophication. This research aims to investigate groundwater pathways from diffuse sources of nitrogen contamination and attenuation processes in various geological settings in Ireland. As part of the EPA Strive Pathways Project, the overall purpose of this research is to improve the understanding of nitrogen attenuation processes in groundwater for the development of a catchment management tool to assess the risk posed by diffuse contamination to surface and groundwater receptors. This will be undertaken through examining nitrogen attenuation pathways in various geological settings in distinctly different catchments in Ireland. These catchments include Gortinlieve in Co. Donegal and Mattock in Co. Louth which are both poorly drained catchments and Nuenna in Co. Kilkenny which is a well drained limestone catchment. This research will be useful to develop further ongoing research carried out into the natural chemistry of the Gortinlieve catchment. The research will focus mainly on characterising the fractionation of stable nitrogen isotopes in groundwater. The use of the stable isotopes δ15N and δ18O in the study of denitrification has been well documented in literature. In addition, the isotopes δ13C and δ34S have also been shown to be useful in evaluating the influence of sulphur and carbon as electron donors in denitrification. For example FeS2 produced as a result of denitrification has a different isotopic signature than FeS2 produced from other processes. This research aims to apply these established stable isotope signatures to a new context in terms of the catchment geology and the broader integrated approach of the Pathways project. Furthermore factors influencing the rate of attenuation will be explored, such as: strata

  20. Strategy for designing stable and powerful nitrogen-rich high-energy materials by introducing boron atoms.

    PubMed

    Wu, Wen-Jie; Chi, Wei-Jie; Li, Quan-Song; Li, Ze-Sheng

    2017-06-01

    One of the most important aims in the development of high-energy materials is to improve their stability and thus ensure that they are safe to manufacture and transport. In this work, we theoretically investigated open-chain N4B2 isomers using density functional theory in order to find the best way of stabilizing nitrogen-rich molecules. The results show that the boron atoms in these isomers are aligned linearly with their neighboring atoms, which facilitates close packing in the crystals of these materials. Upon comparing the energies of nine N4B2 isomers, we found that the structure with alternating N and B atoms had the lowest energy. Structures with more than one nitrogen atom between two boron atoms had higher energies. The energy of N4B2 increases by about 50 kcal/mol each time it is rearranged to include an extra nitrogen atom between the two boron atoms. More importantly, our results also show that boron atoms stabilize nitrogen-rich molecules more efficiently than carbon atoms do. Also, the combustion of any isomer of N4B2 releases more heat than the corresponding isomer of N4C2 does under well-oxygenated conditions. Our study suggests that the three most stable N4B2 isomers (BN13, BN24, and BN34) are good candidates for high-energy molecules, and it outlines a new strategy for designing stable boron-containing high-energy materials. Graphical abstract The structural characteristics, thermodynamic stabilities, and exothermic properties of nitrogen-rich N4B2 isomers were investigated by means of density functional theory.

  1. The oligotrophic ocean is autotrophic.

    PubMed

    Williams, Peter J le B; Quay, Paul D; Westberry, Toby K; Behrenfeld, Michael J

    2013-01-01

    In vitro observations of net community production (NCP) imply that the oligotrophic subtropical gyres of the open ocean are net heterotrophic; in situ observations, in contrast, consistently imply that they are net autotrophic. At least one approach must be returning an incorrect answer. We find that (a) no bias in in situ oxygen-based production estimates would give false-positive (net autotrophy) rates, (b) observed (13)C enrichment of surface water dissolved inorganic carbon (DIC) can be explained only by positive NCP (net autotrophy), (c) lateral and vertical inputs of organic carbon are insufficient to sustain net heterotrophy, and (d) atmospheric input of organic material is too small to support in vitro rates of net heterotrophy and would yield δ(13)C depletion of surface DIC, quite the opposite of what is observed in the subtropical gyres. We conclude that the in vitro observations, implying net heterotrophy, must contain a bias that is due to an underestimate of photosynthetic rate and/or an overestimate of respiration rate.

  2. Carbon and nitrogen utilization in two species of Red Sea corals along a depth gradient: Insights from stable isotope analysis of total organic material and lipids

    NASA Astrophysics Data System (ADS)

    Alamaru, Ada; Loya, Yossi; Brokovich, Eran; Yam, Ruth; Shemesh, Aldo

    2009-09-01

    We examined the utilization of carbon and nitrogen in two common Red Sea coral species (Stylophora pistillata and Favia favus), differing in colony morphology and polyp size, along a depth gradient down to 60 m. We describe the changes in C/N ratios and in the stable isotope composition of carbon and nitrogen of coral's tissue and algal symbionts. We also measured the carbon isotopic composition of the lipid fraction extracted from both coral tissue and algal symbionts in order to reveal the changes in the carbon source utilized by the host coral for lipid synthesis. The results show that for both species, δ13C decreases by 7-8‰ in animal tissue, algal symbionts and in the lipid fractions as depth increases. However, in contrast to previous reports, the difference between δ13C values of coral tissue and algal symbionts does not increase with depth. δ15N values of coral tissue and algal symbionts in both species do not correlate with depth suggesting that the heterotrophic capacity of these corals does not increase with depth. δ13C values of tissue lipids were depleted by an average of ˜3.5‰ compared to δ13C of the entire tissue at all depths. δ13C values of algal lipids were depleted by an average of ˜2‰ compared to δ13C of the entire zooxanthellae at all depths, indicating high efficiency of carbon recycling between the two symbiotic partners along the entire gradient. The depletion of lipids is attributed to the fractionation mechanism during lipid synthesis. In addition, for both species, δ13C values of algal lipids were enriched compared with δ13C of tissue lipids. In S. pistillata, the difference between δ13C values of tissue lipids and algal lipids increased linearly with depth, indicating a change in the sources of carbon utilized by the coral for lipid synthesis below 20 m from an autotrophic to a heterotrophic source. However, in F. favus, this average difference was ˜4 times larger compared to shallow S. pistillata and was constant

  3. Partial mycoheterotrophy in Pyroleae: nitrogen and carbon stable isotope signatures during development from seedling to adult.

    PubMed

    Johansson, Veronika A; Mikusinska, Anna; Ekblad, Alf; Eriksson, Ove

    2015-01-01

    Mycoheterotrophic plants (MHP) are divided into non-photosynthesizing full MHP and green-leaved partial or initial MHP. We investigated (13)C and (15)N isotope enrichment in five putatively partial MHP species in the tribe Pyroleae (Ericaceae): Chimaphila umbellata, Moneses uniflora, Orthilia secunda, Pyrola chlorantha and Pyrola minor, sampled from forest sites on Öland, Sweden. For M. uniflora and P. chlorantha, we investigated isotope signatures of subterranean seedlings (which are mycoheterotrophic), to examine how the use of seedlings instead of full MHP species (Hypopitys monotropa) as reference species affects the assessment of partial mycoheterotrophy. Our main findings were as follows: (1) All investigated Pyroleae species were enriched in (15)N compared to autotrophic reference plants. (2) significant fungal-derived C among the Pyroleae species was found for O. secunda and P. chlorantha. For the remaining species of C. umbellata, M. uniflora and P. minor, isotope signatures suggested adult autotrophy. (3) C and N gains, calculated using seedlings as a full MHP reference, yielded qualitatively similar results as when using H. monotropa as a reference. However, the estimated differences in C and N gains became larger when using seedlings as an MHP reference. (4) A previously unknown interspecific variation in isotope signature occurs during early ontogeny, from seed production to developing seedlings. Our findings suggest that there is a variation among Pyroleae species concerning partial mycoheterotrophy in adults. Adult autotrophy may be most common in Pyroleae species, and these species may not be as dependent on fungal-derived nutrients as some green orchids.

  4. STUDIES ON THE METABOLISM OF AUTOTROPHIC BACTERIA

    PubMed Central

    Vogler, K. G.

    1942-01-01

    In a study of chemosynthesis (the fixation of CO2 by autotrophic bacteria in the dark) in Thiobacillus thiooxidans, the data obtained support the following conclusions: 1. CO2 can be fixed by "resting cells" of Thiobacillus thiooxidans; the fixation is not "growth bound." 2. The physiological condition of the cell is of considerable importance in determining CO2 fixation. 3. CO2 fixation can occur in the absence of oxidizable sulfur in "young" cells. The extent of this fixation appears to be dependent upon the pCO2. 4. CO2 fixation can also occur under anaerobic conditions and the presence of sulfur does not influence such fixation. 5. However, in the CO2 fixation by cells in the absence of sulfur, only a limited amount of CO2 can be fixed. This amount is approximately 40 µl. CO2 per 100 micrograms bacterial nitrogen. After a culture has utilized this amount of CO2 it no longer has the ability to fix CO2 but releases it during its respiration. 6. Relatively short periods of sulfur oxidation can restore the ability of cells to fix CO2 under conditions where sulfur oxidation is prevented. 7. It is possible to oxidize sulfur in the absence of CO2 and to store the energy thus formed within the cell. It is then possible to use this energy at a later time for the fixation of CO2 in the entire absence of sulfur oxidation. 8. Cultures of Thiobacillus thiooxidans respiring on sulfur utilize CO2 in a reaction which proceeds to a zero concentration of CO2 in the atmosphere. 9. CO2 may act as an oxidizing agent for sulfur. 10. Hydrogen is not utilized by the organism. 11. It is possible to selectively inhibit sulfur oxidation and CO2 fixation. PMID:19873324

  5. Bulk and Compound-Specific Stable Nitrogen Isotopes in Plankton Reveal Large Impact of Diazotrophy across the Subtropical North Atlantic

    NASA Astrophysics Data System (ADS)

    Mompean de la Rosa, M.; McCarthy, M.; Bode, A.

    2012-12-01

    Enhanced stratification linked to global warming is predicted to decrease nutrient input from deep waters, and may therefore increase oligotrophy in the subtropical ocean. However, nitrogen fixation in many subtropical regions also supports a significant fraction of primary production, a process likely to be enhanced by the same warm/stratified conditions. The shifting balance between major nutrient sources with global change may alter subtropical food webs, possibly strongly affecting the production and export of organic matter. In this study we examined the spatial variability of stable nitrogen isotopes in plankton size fractions in the upper 200 m in a high spatial resolution transect across the Atlantic (24N) during the Malaspina-2010. Our main goal was to determine the major origin of nitrogen for plankton production. Bulk stable isotopes in all size fractions showed a nearly symmetrical spatial distribution, with the lowest values (σ15N <1‰) in the central zone, and were inversely correlated to the abundance of the nitrogen-fixer Trichodesmium. Diazotrophy was estimated to account for >50% of organic nitrogen in the central zone, however it was also very significant (>30%) in eastern and western zones. The relative nitrogen contribution from diazotrophy also increased with increasing plankton size fraction, suggesting the increasing concentration (importance) of recently fixed nitrogen at higher trophic levels, with potential implication for sources of exported organic N. To further explore a possible linkage with trophic position, we also measured compound-specific σ15N values of amino acids, which allowed us to explicitly calculate average trophic position for different plankton size classes. The σ15N value of Phe was then used as direct molecular-level proxy for σ15N value of primary production across the plankton size spectrum. These results indicate that the zone influenced by diazotrophy in the North Atlantic is much larger than reported in

  6. Analysis of Microbial Communities in Biofilms from CSTR-Type Hollow Fiber Membrane Biofilm Reactors for Autotrophic Nitrification and Hydrogenotrophic Denitrification.

    PubMed

    Shin, Jung-Hun; Kim, Byung-Chun; Choi, Okkyoung; Kim, Hyunook; Sang, Byoung-In

    2015-10-01

    Two hollow fiber membrane biofilm reactors (HF-MBfRs) were operated for autotrophic nitrification and hydrogenotrophic denitrification for over 300 days. Oxygen and hydrogen were supplied through the hollow fiber membrane for nitrification and denitrification, respectively. During the period, the nitrogen was removed with the efficiency of 82-97% for ammonium and 87-97% for nitrate and with the nitrogen removal load of 0.09-0.26 kg NH4(+)-N/m(3)/d and 0.10-0.21 kg NO3(-)-N/m(3)/d, depending on hydraulic retention time variation by the two HF-MBfRs for autotrophic nitrification and hydrogenotrophic denitrification, respectively. Biofilms were collected from diverse topological positions in the reactors, each at different nitrogen loading rates, and the microbial communities were analyzed with partial 16S rRNA gene sequences in denaturing gradient gel electrophoresis (DGGE). Detected DGGE band sequences in the reactors were correlated with nitrification or denitrification. The profile of the DGGE bands depended on the NH4(+) or NO3(-) loading rate, but it was hard to find a major strain affecting the nitrogen removal efficiency. Nitrospira-related phylum was detected in all biofilm samples from the nitrification reactors. Paracoccus sp. and Aquaspirillum sp., which are an autohydrogenotrophic bacterium and an oligotrophic denitrifier, respectively, were observed in the denitrification reactors. The distribution of microbial communities was relatively stable at different nitrogen loading rates, and DGGE analysis based on 16S rRNA (341f /534r) could successfully detect nitrate-oxidizing and hydrogen-oxidizing bacteria but not ammonium-oxidizing bacteria in the HF-MBfRs.

  7. Phosphorus removal in a sulfur-limestone autotrophic denitrification (SLAD) biofilter.

    PubMed

    Li, Ruihua; Yuan, Yulin; Zhan, Xinmin; Liu, Bo

    2014-01-01

    The sulfur-limestone autotrophic denitrification (SLAD) biofilter was able to remove phosphorous from wastewater during autotrophic denitrification. Parameters influencing autotrophic denitrification in the SLAD biofilter, such as hydraulic retention time (HRT), influent nitrate (NO3(-)), and influent PO4(3-) concentrations, had significant effects on P removal. P removal was well correlated with total oxidized nitrogen (TON) removed in the SLAD biofilter; the more TON removed, the more efficient P removal was achieved. When treating the synthetic wastewater containing NO3(-)-N of 30 mg L(-1) and PO4(3-)-P of 15 mg L(-1), the SLAD biofilter removed phosphorus of 45% when the HRT was 6 h, in addition with TN removal of nearly 100%. The optimal phosphorus removal in the SLAD biofilter was around 60%. For the synthetic wastewater containing a PO4(3-)-P concentration of 15 mg L(-1), the main mechanism of phosphorus removal was the formation of calcium phosphate precipitates.

  8. Carbon and nitrogen stable isotope turnover rates and diet-tissue discrimination in Florida manatees (Trichechus manatus latirostris).

    PubMed

    Alves-Stanley, Christy D; Worthy, Graham A J

    2009-08-01

    The Florida manatee (Trichechus manatus latirostris) is a herbivorous marine mammal that occupies freshwater, estuarine and marine habitats. Despite being considered endangered, relatively little is known about its feeding ecology. The present study expands on previous work on manatee feeding ecology by providing critical baseline parameters for accurate isotopic data interpretation. Stable carbon and nitrogen isotope ratios were examined over a period of more than 1 year in the epidermis of rescued Florida manatees that were transitioning from a diet of aquatic forage to terrestrial forage (lettuce). The mean half-life for (13)C turnover was 53 and 59 days for skin from manatees rescued from coastal and riverine regions, respectively. The mean half-life for (15)N turnover was 27 and 58 days, respectively. Because of these slow turnover rates, carbon and nitrogen stable isotope analysis in manatee epidermis is useful in summarizing average dietary intake over a long period of time rather than assessing recent diet. In addition to turnover rate, a diet-tissue discrimination value of 2.8 per thousand for (13)C was calculated for long-term captive manatees on a lettuce diet. Determining both turnover rate and diet-tissue discrimination is essential in order to accurately interpret stable isotope data.

  9. Coastal sediments under the influence of multiple organic enrichment sources: An evaluation using carbon and nitrogen stable isotopes.

    PubMed

    Sampaio, Leandro; Freitas, Rosa; Máguas, Cristina; Rodrigues, Ana; Quintino, Victor

    2010-02-01

    Sediment descriptors (grain size, total volatile solids, redox potential) and stable carbon and nitrogen isotopes were used to trace the origin of organic matter in a coastal area under multiple organic enrichment sources (urban outfall and a major estuary). The sediments fines content and total volatile solids were similar to outfall pre-operation period (1994), but the incorporation of terrestrial organic matter within the sediments located closer to the outfall was diagnosed by depleted (13)C values (-24.2+/-0.38 per thousand) and (15)N values (2.4+/-0.93 per thousand). Data also indicated depleted nitrogen signature at larger distances from the outfall than the carbon signature, due to confounding sediment grain size properties. Analysis in the bivalve Abra alba gave the same results for both isotopes and thus allowed a coherent interpretation of the spatial extent of the organic enrichment, highlighting the importance of bringing a biological element into the environmental assessment.

  10. Stable nitrogen isotope ratios of bone collagen reflect marine and terrestrial components of prehistoric human diet

    SciTech Connect

    Schoeninger, M.J.; DeNiro, M.J.; Tauber, H.

    1983-06-24

    delta/sup 15/N values of bone collagen from Eskimos and from Northwst Coast Indians dependent on salmon fishing are about 10 per mil more positive than those from agriculturalists in historic times. Among prehistoric humans, two groups dependent on marine food sources show bone collagen delta/sup 15/N values that are 4 to 6 per mil more positive than those from two agricultural groups. The nitrogen isotope ratios of bone collagen from prehistoric inhabitants of Bahamas are anomalously low for reasons that relate to the biogeochemical cycle of nitrogen in coral reefs.

  11. Post-depositional fractionation of nitrate stable isotopes in Antarctic snow: towards constraining past UV radiation and reactive nitrogen cycling

    NASA Astrophysics Data System (ADS)

    Frey, M. M.; Morin, S.; Savarino, J. P.; Erbland, J.

    2009-12-01

    Recent studies on atmospheric particulate nitrate (NO3-) demonstrated that the nitrogen and triple oxygen stable isotopic composition of NO3- allows constraining not only atmospheric sources and sinks but also oxidation pathways of reactive nitrogen. However, extending this tool to past atmospheres using ice cores can be complicated by post-depositional mass loss and fractionation via UV-photolysis and evaporation. A new 60-yr firn record of 15N/14N and 18O/16O isotopic ratios in NO3- from Dome C, Antarctica (75° S, 123° E) shows strong fractionation compared to the atmospheric signal and a significant anti-correlation (r=-0.75, p<0.01). We propose that at low accumulation sites the nitrate stable isotope record preserves the imprint of processes driving post-depositional fractionation and therefore can be used to infer past levels of UV-radiation and NO3- loss from snow. The former is supported by a strong correlation between δ15N(NO3-) and modeled annual UV radiation at Dome C (r = 0.7, p<0.001). Furthermore, first quantum-chemical model calculations of the photolytic fractionation constant of the nitrogen isotope are consistent with field and lab observations and show a strong sensitivity to the spectrum of actinic flux. We discuss the proposed model framework as a first step towards an isotopic atmosphere-snow transfer function and implications not only for ice core interpretation but also for our understanding of reactive nitrogen cycling above snow surfaces.

  12. Use of stable isotopes of carbon, nitrogen, and sulfer to identify sources of nitrogen in surface waters in the Lower Susquehanna River basin, Pennsylvania

    USGS Publications Warehouse

    Cravotta, C.A.

    1995-01-01

    Stable isotopes of carbon (C), nitrogen (N), and sulfur (S) in nitrogen sources and nearby samples of topsoil, subsoil, runoff water, and stream water were measured to evaluate the feasibility of using isotopic data to identify nitrogen sources in stream water from forested, agricultural, or suburban land-use areas. Chemical and isotopic compositions were measured for six N-source types consisting of rain water, forest-leaf litter, synthetic fertilizer, farm-animal manure, municipal-sewage effluent and sludge, and septic-tank effluent and sludge. Compositions of topsoil, subsoil, runoff water, and stream water were measured to evaluate changes in compositions of transported N-containing materials near the N source. Animal manure, human waste (sewage plus septic), and forest-leaf litter can be distinguished on the basis of C; however, most N-sources can not be distinguished on the basis of N and S, owing to wide ranges of compositions and overlap among different N-source types. Although values of N for soil and runoff-water samples are qualitatively similar to those of the applied N source, values of C and S for runoff-water and stream-water samples appear to reflect the compositions of relatively large reservoirs of the elements in soil organic matter and minerals, respectively, and not the composition of the applied N source. Because of incomplete chemical transfor- mations, the ratio of organic carbon to total nitrogen for particulates in runoff or stream waters generally is lower than that for associated, nearby soils, and isotopic compositions commonly differ between particulate and dissolved fractions in the water.

  13. Stable isotopes of carbon and nitrogen in the study of avian and mammalian trophic ecology

    Treesearch

    Jeffrey F. Kelly

    2000-01-01

    Differential fractionation of stable isotopes of carbon during photosynthesis causes C4 plants and C3 plants to have distinct carbon-isotope signatures. In addition, marine C3 plants have stable-isotope ratios of carbon that are intermediate between C4 and terrestrial C3 plants. The direct incorporation of the carbon-isotope ratio (13C/12C) of plants into consumers...

  14. Starvation effects on nitrogen and carbon stable isotopes of animals: an insight from meta-analysis of fasting experiments.

    PubMed

    Doi, Hideyuki; Akamatsu, Fumikazu; González, Angélica L

    2017-08-01

    Nitrogen and carbon stable isotopic compositions (δ(15)N and δ(13)C) of consumers have been used for physiological and food web studies. Previous studies have shown δ(15)N and δ(13)C values are affected by several biological and environmental factors during starvation, but the generality of the effect of starvation on δ(15)N and δ(13)C values has not yet been tested. Here, we performed a meta-analysis to evaluate the effects of starvation on δ(15)N and δ(13)C values of consumers, and the underlying factors that may explain the observed variation. The δ(15)N and δ(13)C values were calculated as the differences between the final δ(15)N and δ(13)C values of consumers (post-starvation) and the pre-starvation values on each experiment. Our meta-analysis showed a large variation in the δ(15)N and δ(13)C values of consumers (δ(15)N range: -0.82 to 4.30‰; mean: 0.47‰ and δ(13)C range: -1.92 to 2.62‰; mean: 0.01‰). The δ(15)N values of most consumers increased along the length of the starvation period and were influenced by nitrogen excretion and thermoregulation types, probably because differences in nitrogen metabolism and thermoregulation affect nitrogen processing and excretion rates. None of our predictor variables accounted for the variation in δ(13)C values, which showed both increases and decreases due to fasting. Our findings suggest that starvation results in changes in consumer δ(15)N values which are mainly explained by the length of the fasting period and by nitrogen and energy metabolism, but the underlying mechanisms of the starvation effects on δ(13)C values seem to be more complex than previously thought.

  15. Autotrophic ammonia oxidation in a deep-sea hydrothermal plume.

    PubMed

    Lam, Phyllis; Cowen, James P; Jones, Ronald D

    2004-02-01

    Direct evidence for autotrophic ammonia oxidation is documented for the first time in a deep-sea hydrothermal plume. Elevated NH(4) (+) concentrations of up to 341+/-136 nM were recorded in the plume core at Main Endeavour Field, Juan de Fuca Ridge. This fueled autotrophic ammonia oxidation rates as high as 91 nM day(-1), or 92% of the total net NH(4) (+) removal. High abundance of ammonia-oxidizing bacteria was detected using fluorescence in situ hybridization. Ammonia-oxidizing bacteria within the plume core (1.0-1.4x10(4) cells ml(-1)) accounted for 7.0-7.5% of the total microbial community, and were at least as abundant as methanotrophs. Ammonia-oxidizing bacteria were a substantial component of the particle-associated communities (up to 51%), with a predominance of the r-strategist Nitrosomonas-like cells. In situ chemolithoautotrophic organic carbon production via ammonia oxidation may yield 3.9-18 mg C m(-2) day(-1) within the plume directly over Main Endeavour Field. This rate was comparable to that determined for methane oxidation in a previous study, or at least four-fold greater than the flux of photosynthetic carbon reaching plume depths measured in another study. Hence, autotrophic ammonia oxidation in the neutrally buoyant hydrothermal plume is significant to both carbon and nitrogen cycling in the deep-sea water column at Endeavour, and represents another important link between seafloor hydrothermal systems and deep-sea biogeochemistry.

  16. Stable isotope fractionation related to microbial nitrogen turnover in constructed wetlands treating contaminated groundwater

    NASA Astrophysics Data System (ADS)

    Voloshchenko, O.; Knoeller, K.

    2013-12-01

    To improve the efficiency of ground- and wastewater treatment in constructed wetlands (CWs), better understanding of the occurring processes is necessary. This research explores N-isotope fractionations associated with the removal of ammonium from contaminated groundwater in pilot-scale CWs downstream of the chemical industrial area Leuna, Germany. The groundwater at the site is contaminated mainly by organic (BTEX, MTBE) and inorganic compounds (ammonium). We assume that the anaerobic ammonium oxidation (ANAMMOX) plays an important role in nitrogen removal in these CWs. However, to date, interactions between processes of aerobic and anaerobic ammonium oxidation in CWs still have not been well explored. Especially, the importance of the ANAMMOX process for the nitrogen removal is generally accepted, but its role in CWs is quite unknown. For this aim, three CWs were chosen: planted horizontal subsurface flow (HSSF); unplanted HSSF, and floating plant root mat (FPRM). Water samples were taken at the inflow and outflow as well as from the pore space at different distances (1, 2.5 and 4 m) from the inlet and at different depths (20, 30 and 40 cm in the HSSF-CWs, 30 cm in the FPRM). Samples were collected in a time interval of 1 to 6 weeks during 1 year with the exception of the winter season. Physicochemical parameters, nitrogen isotope signatures of ammonium, as well as nitrogen and oxygen isotope signatures of nitrate were analysed. Within the CWs, spatial concentration gradients of the nitrogen species (ammonium and nitrate) are observed. N-isotope variations of ammonium and nitrate are interpreted according to the prevailing processes of the N-transformations. Based on isotope mass-balance approach microbial processes such as nitrification, denitrification, and ANAMMOX are quantified. DNA from biofilms at roots and gravel was extracted using FastDNA Spin Kit For Soil (MP Biomedicals). PCR, quantitative PCR, cloning, and sequencing were applied with the purpose of

  17. Patterns in Stable Isotope Values of Nitrogen and Carbon in Particulate Matter from the Northwest Atlantic Continental Shelf, from the Gulf of Maine to Cape Hatteras

    EPA Science Inventory

    Stable isotope measurements of nitrogen and carbon (15N, 13ddC) are often used to characterize estuarine, nearshore, and open ocean ecosystems. Reliable information about the spatial distribution of base-level stable isotope values, often represented by primary producers, is crit...

  18. Patterns in Stable Isotope Values of Nitrogen and Carbon in Particulate Matter from the Northwest Atlantic Continental Shelf, from the Gulf of Maine to Cape Hatteras

    EPA Science Inventory

    Stable isotope measurements of nitrogen and carbon (15N, 13ddC) are often used to characterize estuarine, nearshore, and open ocean ecosystems. Reliable information about the spatial distribution of base-level stable isotope values, often represented by primary producers, is crit...

  19. Nitrogen

    USGS Publications Warehouse

    Apodaca, Lori E.

    2013-01-01

    The article presents an overview of the nitrogen chemical market as of July 2013, including the production of ammonia compounds. Industrial uses for ammonia include fertilizers, explosives, and plastics. Other topics include industrial capacity of U.S. ammonia producers CF Industries Holdings Inc., Koch Nitrogen Co., PCS Nitrogen, Inc., and Agrium Inc., the impact of natural gas prices on the nitrogen industry, and demand for corn crops for ethanol production.

  20. Stable isotopes (carbon, nitrogen, sulfur), diet, and anthropometry in urban Colombian women: investigating socioeconomic differences.

    PubMed

    Bender, Richard L; Dufour, Darna L; Valenzuela, Luciano O; Cerling, Thure E; Sponheimer, Matt; Reina, Julio C; Ehleringer, James R

    2015-01-01

    We conducted stable isotope and dietary analyses of women from higher and lower socioeconomic status (SES) groups in Cali, Colombia. The objectives were to test between-group differences in stable isotope, dietary, and anthropometric characteristics, and to evaluate relationships between diet and stable isotope values. Hair samples from 38 women (mean age 33.4) from higher and lower SES groups were analyzed for δ(13) C, δ(15) N, and δ(34) S values. Dietary intake was assessed via 24-h recalls. Anthropometric variables measured were body mass index, five body circumferences, and six skinfold thicknesses. Mean δ(13) C and δ(15) N values of the higher SES group (-16.4 and 10.3‰) were significantly greater than those of the lower SES group (-17.2 and 9.6‰; P < 0.01), but mean δ(34) S values did not differ significantly between groups (higher SES: 4.6‰; lower SES: 5.1‰). The higher SES group consumed a greater percentage of protein than the lower SES group (14% vs. 12% of energy; P = 0.03), but the groups did not differ in other dietary characteristics or in anthropometric characteristics. δ(13) C, δ(15) N, and δ(34) S values were not correlated with intake of the dietary items predicted (sugars, animal-source protein, and marine foods, respectively). The lower SES group was more variable in all three stable isotope values (P < 0.05), mirroring a trend toward greater dietary variability in this group. Stable isotope values revealed a difference between SES groups that was not explained by the dietary data. The relationship between diet and stable isotope composition is complex. © 2014 Wiley Periodicals, Inc.

  1. Interchange for Joint Research Entitled: Measurement of Stable Nitrogen and Sulfur Isotopes

    NASA Technical Reports Server (NTRS)

    Becker, Joseph F.; Valentin, Jose

    1997-01-01

    Viking measurements of the Martian atmosphere indicate a value of N-15/N-14 which is markedly greater than that found in Earth's atmosphere. These isotopic measurements provide a powerful diagnostic tool which may be used to derive valuable information regarding the past history of Mars and they have been used to place important constraints on the evolution of Mars' atmosphere. Initial partial pressures of nitrogen, outgassing rates, and integrated deposition of nitrogen into minerals have been calculated from this important atmospheric data (McElroy et al., 1976 and 1977; Fox and Dalgarno, 1983). The greater precision obtained in laser spectrometer isotopic measurements compared to the Viking data will greatly improve these calculated values. It has also been proposed that the N-15/N-14 value in Mars' atmosphere has increased monotonically over time (McElroy et al., 1977; Fox and Dalgarno, 1983; Wallis, 1989) owing to preferential escape of atmospheric 14N to space. Nitrogen isotopic ratios might be used to identify relatively ancient crustal rocks (R. Mancinelli, personal communication), and perhaps determine relative aces of surface samples. As a first step in successfully measuring nitrogen isotopes optically we have demonstrated the measurement of 15NI14N to a precision of 0.1% (See Figures 1-4) using a tunable diode laser and an available gas (N-,O) with spectral lines in the 2188 cm-1 region. The sample and reference gas cells contained gases of identical isotopic composition so that the 15NI14N absorption ratio determined from the sample cell, when divided by the 15NI14N absorption ratio determined from the reference cell, should yield an ideal value of unity. The average measured value of this "ratio of ratios" was 0.9983 with a standard deviation (20 values) of 0.0010. This corresponds to a precision of 0.1% (1 per mil) for nitrogen isotopes, a value sufficiently precise to provide important isotopic data of interest to exobiologists. The precision

  2. Carbon and Nitrogen Stable Isotope Ratios Predict Intake of Sweeteners in a Yup’ik Study Population12

    PubMed Central

    Nash, Sarah H.; Kristal, Alan R.; Bersamin, Andrea; Hopkins, Scarlett E.; Boyer, Bert B.; O’Brien, Diane M.

    2013-01-01

    The carbon isotope ratio (δ13C) is elevated in corn- and cane sugar-based foods and has recently shown associations with sweetener intake in multiple U.S. populations. However, a high carbon isotope ratio is not specific to corn- and sugar cane-based sweeteners, as other foods, including meats and fish, also have elevated δ13C. This study examines whether the inclusion of a second marker, the nitrogen isotope ratio (δ15N), can control for confounding dietary effects on δ13C and improve the validity of isotopic markers of sweetener intake. The study participants are from the Yup’ik population of southwest Alaska and consume large and variable amounts of fish and marine mammals known to have elevated carbon and nitrogen isotope ratios. Sixty-eight participants completed 4 weekly 24-h recalls followed by a blood draw. RBC δ13C and δ15N were used to predict sweetener intake, including total sugars, added sugars, and sugar-sweetened beverages. A model including both δ13C and δ15N explained more than 3 times as much of the variation in sweetener intake than did a model using only δ13C. Because carbon and nitrogen isotope ratios are simultaneously determined in a single, high-throughput analysis, this dual isotope marker provides a simple method to improve the validity of stable isotope markers of sweetener intake with no additional cost. We anticipate that this multi-isotope approach will have utility in any population where a stable isotope biomarker is elevated in several food groups and there are appropriate “covariate” isotopes to control for intake of foods not of research interest. PMID:23256142

  3. Trophic ecology and vertical patterns of carbon and nitrogen stable isotopes in zooplankton from oxygen minimum zone regions

    NASA Astrophysics Data System (ADS)

    Williams, Rebecca L.; Wakeham, Stuart; McKinney, Rick; Wishner, Karen F.

    2014-08-01

    The unique physical and biogeochemical characteristics of oxygen minimum zones (OMZs) influence plankton ecology, including zooplankton trophic webs. Using carbon and nitrogen stable isotopes, this study examined zooplankton trophic webs in the Eastern Tropical North Pacific (ETNP) OMZ. δ13C values were used to indicate zooplankton food sources, and δ15N values were used to indicate zooplankton trophic position and nitrogen cycle pathways. Vertically stratified MOCNESS net tows collected zooplankton from 0 to 1000 m at two stations along a north-south transect in the ETNP during 2007 and 2008, the Tehuantepec Bowl and the Costa Rica Dome. Zooplankton samples were separated into four size fractions for stable isotope analyses. Particulate organic matter (POM), assumed to represent a primary food source for zooplankton, was collected with McLane large volume in situ pumps. The isotopic composition and trophic ecology of the ETNP zooplankton community had distinct spatial and vertical patterns influenced by OMZ structure. The most pronounced vertical isotope gradients occurred near the upper and lower OMZ oxyclines. Material with lower δ13C values was apparently produced in the upper oxycline, possibly by chemoautotrophic microbes, and was subsequently consumed by zooplankton. Between-station differences in δ15N values suggested that different nitrogen cycle processes were dominant at the two locations, which influenced the isotopic characteristics of the zooplankton community. A strong depth gradient in zooplankton δ15N values in the lower oxycline suggested an increase in trophic cycling just below the core of the OMZ. Shallow POM (0-110 m) was likely the most important food source for mixed layer, upper oxycline, and OMZ core zooplankton, while deep POM was an important food source for most lower oxycline zooplankton (except for samples dominated by the seasonally migrating copepod Eucalanus inermis). There was no consistent isotopic progression among the four

  4. Nitrate removal and microbial analysis by combined micro-electrolysis and autotrophic denitrification.

    PubMed

    Xing, Wei; Li, Desheng; Li, Jinlong; Hu, Qianyi; Deng, Shihai

    2016-07-01

    A process combining micro-electrolysis and autotrophic denitrification (CEAD) with iron-carbon micro-electrolysis carriers was developed for nitrate removal. The process was performed using organic-free influent with a NO3(-)-N concentration of 40.0±3.0mg/L and provided an average nitrate removal efficiency of 95% in stable stages. The total nitrogen removal efficiency reached 75%, with 21% of NO3(-)-N converted into NH4(+)-N. The corresponding hydraulic retention time was 8-10h, and the optimal pH ranged from 8.5 to 9.5. Microbial analysis with high-throughput sequencing revealed that dominant microorganisms in the reactor belonged to the classes of β-, γ-, and α-Proteobacteria. The abundance of the genera Thermomonas significantly increased during the operation, comprising 21.4% and 24.1% in sludge attached to the carriers in the middle and at the bottom of the reactor, respectively. The developed CEAD achieved efficient nitrate removal from water without organics, which is suitable for practical application. Copyright © 2016. Published by Elsevier Ltd.

  5. Using Stable Isotopes of Carbon and Nitrogen to Evaluate Trophic Interactions in Aquatic Environments

    ERIC Educational Resources Information Center

    Christensen, David R.; LaRoche, Andrew

    2012-01-01

    This paper describes a series of laboratory exercises for upper level biology courses, independent research and/or honors programs. Students sampled fish from a local water body with the assistance of a local fish and wildlife agency. Tissue samples from collected fish were utilized to obtain estimates of the stable isotopes delta[superscript 13]C…

  6. Interannual Variation in Stable Carbon and Nitrogen Isotope Biogeochemistry of the Mattaponi River, Virginia

    EPA Science Inventory

    This manuscript addresses the difficult issue of identifying the origin of particulate organic matter (POM) in estuaries . . . The objectives of this study were to quantify spatial and temporal variability of the C and N stable isotope composition of suspended POM, and to identif...

  7. Comparison of heterotrophic and autotrophic denitrification processes for treating nitrate-contaminated surface water.

    PubMed

    Wang, Zheng; Fei, Xiang; He, Shengbing; Huang, Jungchen; Zhou, Weili

    2017-02-01

    The goal of this study was to compare the nitrogen removal rate, effluent algal growth potential (AGP), nitrous oxide (N2O) emissions and global warming potential (GWP) between two laboratory-scale bioreactors: the autotrophic denitrification biofilter (ADBF) and heterotrophic denitrification biofilter (HDBF) for treating nitrate-contaminated surface water. The comparative study of nitrogen removal rate between ADBF and HDBF was conducted by a long-term experiment, and the comparative study of the effluent AGP, N2O emissions and GWP between ADBF and HDBF were carried out by the corresponding batch tests. The results show that the heterotrophic and autotrophic denitrification rates were close to each other. Besides, the AGP of the ADBF effluent was 2.08 times lower than that of the HDBF effluent, while the N2O concentration in off-gas emitted from HDBF was 6-8 times higher than that from ADBF. The higher N2O-N emission rate of HDBF was mainly responsible for the higher GWP of HDBF than that of ADBF. Furthermore, with a novel light-weight filtration media (NLWFM) for filtration, the autotrophic denitrification (ADN) process combined with biofilter process would be the optimal denitrification process for nitrogen removal from nitrate-contaminated surface water. The study also provided a systematic method for evaluation of biological nitrogen removal (BNR) process. Copyright © 2016. Published by Elsevier B.V.

  8. Investigating trophic relationships of pinnipeds in Alaska and Washington using stable isotope ratios of nitrogen and carbon

    USGS Publications Warehouse

    Hobson, Keith A.; Sease, John L.; Merrick, Richard L.; Piatt, John F.

    1997-01-01

    We measured stable-nitrogen (δ15N) and stable-carbon (δ13C) isotope ratios in muscle and hair from 7 northern fur seals (Callorhinus ursinus) from the Pribilof Islands, Alaska, and 27 Steller sea lions (Eumetopias jubatus), and 14 harbor seals (Phoca vitulina) from the Gulf of Alaska and coast of Washington State, in order to contrast dietary information derived from isotopic vs. available conventional dietary studies. Stable-nitrogen-isotope analysis of muscle revealed that harbor seals were enriched over sea lions (mean δ15N = 18.6‰vs. 17.5‰) which were in turn enriched over northern fur seals (mean δ15N = 16.6‰). Trophic segregation among these species likely results primarily from differential reliance on herring (Clupea harengus), Atka mackerel (Pleurogrammus monopterygius), and large vs. small walleye pollock (Theregra chalcogramma). According to their δ15N values, adult male Steller sea lions showed a higher trophic position than adult females (mean δ15N: 18.0‰ vs. 17.2‰), whereas adult female northern fur seals were trophically higher than juvenile male fur seals (mean δ15N: 16.5‰vs. 15.0‰). Each of these observed differences likely resulted from differential reliance on squid or differences in the size range of pollock consumed. Three northern fur seal pups showed higher δ15N enrichment over adults (mean 17.7‰vs. 15.8‰) due to their reliance on their mother's milk. Stable-carbon isotope measurements of hair revealed a cline toward more negative values with latitude. Segregation in hair δ13C between Steller sea lions and harbor seals off the coast of Washington (mean δ13C: -13.6‰ vs. -15.0‰) reflected the greater association of harbor seals with freshwater input from the Columbia River. Our study demonstrates the utility of the stable isotope approach to augment conventional dietary analyses of pinnipeds and other marine mammals.

  9. Discharge Driven Nitrogen Dynamics in a Mesoscale River Basin As Constrained by Stable Isotope Patterns.

    PubMed

    Mueller, Christin; Zink, Matthias; Samaniego, Luis; Krieg, Ronald; Merz, Ralf; Rode, Michael; Knöller, Kay

    2016-09-06

    Nitrate loads and corresponding dual-isotope signatures were used to evaluate large scale N dynamics and trends in a river catchment with a strong anthropogenic gradient (forest conservation areas in mountain regions, and intensive agriculturally used lowlands). The Bode River catchment with an area of 3200 km(2) in the Harz Mountains and central German lowlands was investigated by a two years monitoring program including 133 water sampling points each representing a subcatchment. Based on discharge data either observed or simulated by the mesoscale hydrological model (mHM) a load based interpretation of hydrochemical and isotope data was conducted. Nitrate isotopic signatures in the entire catchment are influenced by (I) the contribution of different nitrogen sources, (II) by variable environmental conditions during the formation of nitrate, and (III) by a minor impact of denitrification. For major tributaries, a relationship between discharge and nitrate isotopic signatures is observed. This may in part be due to the fact, that during periods of higher hydrologic activity a higher wash out of isotopically lighter nitrate formed by bacterial nitrification processes of reduced or organic soil nitrogen occurs. Beyond that, in-stream denitrification seems to be more intense during periods of low flow.

  10. Diet and mobility in Early Medieval Bavaria: a study of carbon and nitrogen stable isotopes.

    PubMed

    Hakenbeck, Susanne; McManus, Ellen; Geisler, Hans; Grupe, Gisela; O'Connell, Tamsin

    2010-10-01

    This study investigates patterns of mobility in Early Medieval Bavaria through a combined study of diet and associated burial practice. Carbon and nitrogen isotope ratios were analyzed in human bone samples from the Late Roman cemetery of Klettham and from the Early Medieval cemeteries of Altenerding and Straubing-Bajuwarenstrasse. For dietary comparison, samples of faunal bone from one Late Roman and three Early Medieval settlement sites were also analyzed. The results indicate that the average diet was in keeping with a landlocked environment and fairly limited availability of freshwater or marine resources. The diet appears not to have changed significantly from the Late Roman to the Early Medieval period. However, in the population of Altenerding, there were significant differences in the diet of men and women, supporting a hypothesis of greater mobility among women. Furthermore, the isotopic evidence from dietary outliers is supported by "foreign" grave goods and practices, such as artificial skull modification. These results reveal the potential of carbon and nitrogen isotope analysis for questions regarding migration and mobility.

  11. Stable Carbon and Nitrogen Isotope Ratios of Sodium and Potassium Cyanide as a Forensic Signature

    SciTech Connect

    Kreuzer, Helen W.; Horita, Juske; Moran, James J.; Tomkins, Bruce; Janszen, Derek B.; Carman, April J.

    2012-01-03

    Sodium and potassium cyanide are highly toxic, produced in large amounts by the chemical industry, and linked to numerous high-profile crimes. The U.S. Centers for Disease Control and Prevention has identified cyanide as one of the most probable agents to be used in a future chemical terrorism event. We investigated whether stable C and N isotopic content of sodium and potassium cyanide could serve as a forensic signature for sample matching, using a collection of 65 cyanide samples. A few of these samples displayed non-homogeneous isotopic content associated with degradation to a carbonate salt and loss of hydrogen cyanide. Most samples had highly reproducible isotope content. Of these, >95% could be properly matched based on C and N isotope ratios, with a false match rate <3%. These results suggest that stable C and N isotope ratios are a useful forensic signature for matching cyanide samples.

  12. Stable Carbon and Nitrogen Isotope Ratios of Sodium and Potassium Cyanide as a Forensic Signature

    SciTech Connect

    Kruzer, Helen W; Horita, Juske; Moran, James J; Tomkins, Bruce A; Janszen, Derek B; Carman, April

    2012-01-01

    Sodium and potassium cyanide are highly toxic, produced in large amounts by the chemical industry, and linked to numerous high-profile crimes. The U.S. Centers for Disease Control and Prevention has identified cyanide as one of the most probable agents to be used in a future chemical terrorism event. We investigated whether stable C and N isotopic content of sodium and potassium cyanide could serve as a forensic signature for sample matching, using a collection of 65 cyanide samples. A few of these samples displayed non-homogeneous isotopic content associated with degradation to a carbonate salt and loss of hydrogen cyanide. Most samples had highly reproducible isotope content. Of these, >95% could be properly matched based on C and N isotope ratios, with a false match rate <3%. These results suggest that stable C and N isotope ratios are a useful forensic signature for matching cyanide samples.

  13. Dynamics of autotrophic marine planktonic thaumarchaeota in the East China Sea.

    PubMed

    Hu, Anyi; Yang, Zao; Yu, Chang-Ping; Jiao, Nianzhi

    2013-01-01

    The ubiquitous and abundant distribution of ammonia-oxidizing Thaumarchaeota in marine environments is now well documented, and their crucial role in the global nitrogen cycle has been highlighted. However, the potential contribution of Thaumarchaeota in the carbon cycle remains poorly understood. Here we present for the first time a seasonal investigation on the shelf region (bathymetry≤200 m) of the East China Sea (ECS) involving analysis of both thaumarchaeal 16S rRNA and autotrophy-related genes (acetyl-CoA carboxylase gene, accA). Quantitative PCR results clearly showed a higher abundance of thaumarchaeal 16S and accA genes in late-autumn (November) than summer (August), whereas the diversity and community structure of autotrophic Thaumarchaeota showed no statistically significant difference between different seasons as revealed by thaumarchaeal accA gene clone libraries. Phylogenetic analysis indicated that shallow ecotypes dominated the autotrophic Thaumarchaeota in the ECS shelf (86.3% of total sequences), while a novel non-marine thaumarchaeal accA lineage was identified in the Changjiang estuary in summer (when freshwater plumes become larger) but not in autumn, implying that Changjiang freshwater discharge played a certain role in transporting terrestrial microorganisms to the ECS. Multivariate statistical analysis indicated that the biogeography of the autotrophic Thaumarchaeota in the shelf water of the ECS was influenced by complex hydrographic conditions. However, an in silico comparative analysis suggested that the diversity and abundance of the autotrophic Thaumarchaeota might be biased by the 'universal' thaumarchaeal accA gene primers Cren529F/Cren981R since this primer set is likely to miss some members within particular phylogenetic groups. Collectively, this study improved our understanding of the biogeographic patterns of the autotrophic Thaumarchaeota in temperate coastal waters, and suggested that new accA primers with improved coverage

  14. Freezing and fractionation: effects of preservation on carbon and nitrogen stable isotope ratios of some limnetic organisms.

    PubMed

    Wolf, J Marshall; Johnson, Brett; Silver, Douglas; Pate, William; Christianson, Kyle

    2016-03-15

    Stable isotopes of carbon and nitrogen have become important natural tracers for studying food-web structure and function. Considerable research has demonstrated that chemical preservatives and fixatives shift the isotopic ratios of aquatic organisms. Much less is known about the effects of freezing as a preservation method although this technique is commonly used. We conducted a controlled experiment to test the effects of freezing (-10 °C) and flash freezing (–79 °C) on the carbon and nitrogen isotope ratios of zooplankton (Cladocera), Mysis diluviana and Rainbow Trout (Oncorhynchus mykiss). Subsamples (~0.5 mg) of dried material were analyzed for percentage carbon, percentage nitrogen, and the relative abundance of stable carbon and nitrogen isotopes (δ13C and δ15N values) using a Carlo Erba NC2500 elemental analyzer interfaced to a ThermoFinnigan MAT Delta Plus isotope ratio mass spectrometer. The effects of freezing were taxon-dependent. Freezing had no effect on the isotopic or elemental values of Rainbow Trout muscle. Effects on the δ13C and δ15N values of zooplankton and Mysis were statistically significant but small relative to typical values of trophic fractionation. The treatment-control offsets had larger absolute values for Mysis (δ13C: ≤0.76 ± 0.41‰, δ15N: ≤0.37 ± 0.16‰) than for zooplankton (δ13C: ≤0.12 ± 0.06‰, δ15N: ≤0.30 ± 0.27‰). The effects of freezing were more variable for the δ13C values of Mysis, and more variable for the δ15N values of zooplankton. Generally, both freezing methods reduced the carbon content of zooplankton and Mysis, but freezing had a negative effect on the %N of zooplankton and a positive effect on the %N of Mysis. The species-dependencies and variability of freezing effects on aquatic organisms suggest that more research is needed to understand the mechanisms responsible for freezing-related fractionation before standardized protocols for freezing as a preservation method can be adopted.

  15. Stable carbon isotope evidence for nitrogenous fertilizer impact on carbonate weathering in a small agricultural watershed.

    PubMed

    Brunet, F; Potot, C; Probst, A; Probst, J-L

    2011-10-15

    The isotopic signature of Dissolved Inorganic Carbon (DIC), δ(13)C(DIC), has been investigated in the surface waters of a small agricultural catchment on calcareous substratum, Montoussé, located at Auradé (south-west France). The Montoussé catchment is subjected to intense farming (wheat/sunflower rotation) and a moderated application of nitrogenous fertilizers. During the nitrification of the NH(4)(+), supplied by fertilization, nitrate and H(+) ions are produced in the soil. This anthropogenic acidity is combined with the natural acidity due to carbonic acid in weathering processes. From an isotopic point of view, with 'natural weathering', using carbonic acid, δ(13)C(DIC) is intermediate between the δ(13)C of soil CO(2) produced by organic matter oxidation and that of the carbonate rocks, while it has the same value as the carbonates when carbonic acid is substituted by another acid like nitric acid derived from nitrogen fertilizer. The δ(13)C(DIC) values range from -17.1‰ to -10.7‰ in Montoussé stream waters. We also measured the δ(13)C of calcareous molassic deposits (average -7.9‰) and of soil organic carbon (between -24.1‰ and -26‰) to identify the different sources of DIC and to estimate their contribution. The δ(13) C(DIC) value indicates that weathering largely follows the carbonic acid pathway at the springs (sources of the stream). At the outlet of the basin, H(+) ions, produced during the nitrification of N-fertilizer, also contribute to weathering, especially during flood events. This result is illustrated by the relationship between δ(13)C(DIC) and the molar ratio NO(3)(-)/(Ca(2+) + Mg(2+)). Consequently, when the contribution of nitrate increases, the δ(13)C(DIC) increases towards the calcareous end-member. This new isotopic result provides evidence for the direct influence of nitrogen fertilizer inputs on weathering, CO(2) consumption and base cation leaching and confirms previous results obtained using the chemistry of the

  16. Implications of CO2 Geological Storage on Aquifers Autotrophic Communities

    NASA Astrophysics Data System (ADS)

    Dupraz, Sébastien; Fabbri, Antonin; Joulian, Catherine; Menez, Bénédicte; Gerard, Emanuelle; Henry, Benoit; Crouzet, Catherine; Guyot, François; Garrido, Francis

    2010-05-01

    In a global strategy of carbon emission reduction, a study about CCS (Carbon Capture and Storage) feasibility in the case of a French beet sugar factory and distillery in the Parisian basin was undertaken by regional and state authorities. Besides, economical, geological and engineering questions, microbial interactions were also studied since the potential contribution of the deep biosphere on the storage zones appears to be an essential factor in terms of injectivity and CO2 mobilization. Biological processes like biofilm formation, biomineralization and carbon assimilation may hinder the injections or, to the contrary, improve the stability of the sequestration by shifting CO2 into more stable forms like carbonates and organic matter. Regarding those possibilities, it is thus mandatory to establish how the subsurface biosphere will react by determining which metabolisms will be able to sustain the stress due to high concentrations of CO2 and the resulting acidification. In that case, the study of autotrophic communities reactivity is essential because they are the only entrance for CO2 assimilation in the SLiMEs (Subsurface Litho autotrophic Microbial Ecosystems) and thus are accountable for the general biomass and biofilm production in the deep subsurface. Nevertheless, a simple assessment of the toxical effect induced on these strains cannot be representative of the possible interactions at the scale of a long term storage where adaptations should play a major role. For that reason, we decided to choose different strains, namely autotrophic methanogens (Methanothermococcus thermolithotrophicus and Archeoglobus fulgidus) and sulfate reducing bacteria strains (Desulfotomaculum geothermicum and Desulfotomaculum kuznetsovii), that best characterize the autotrophic communities of our injection site (aquifer of the Triassic Keuper sandstones) and to make them undergo a test of selection/adaptation toward a sequential increase of CO2 partial pressure from 0.05 to 5

  17. Variation in trophic shift for stable isotope ratios of carbon, nitrogen, and sulfur

    USGS Publications Warehouse

    McCutchan, J.H.; Lewis, W.M.; Kendall, C.; McGrath, C.C.

    2003-01-01

    Use of stable isotope ratios to trace pathways of organic matter among consumers requires knowledge of the isotopic shift between diet and consumer. Variation in trophic shift among consumers can be substantial. For data from the published literature and supplementary original data (excluding fluid-feeding consumers), the mean isotopic shift for C was +0.5 ?? 0.13??? rather than 0.0???, as commonly assumed. The shift for C was higher for consumers analyzed as muscle (+1.3 ?? 0.30???) than for consumers analyzed whole (+0.3 ?? 0.14???). Among consumers analyzed whole, the trophic shift for C was lower for consumers acidified prior to analysis (-0.2 ?? 0.21???) than for unacidified samples (+0.5 ?? 0.17???). For N, trophic shift was lower for consumers raised on invertebrate diets (+1.4 ?? 0.21???) than for consumers raised on other high-protein diets (+3.3 ?? 0.26???) and was intermediate for consumers raised on plant and algal diets (+2.2 ?? 0.30???). The trophic shift for S differed between high-protein (+2.0 ?? 0.65???) and low-protein diets (-0.5 ?? 0.56???). Thus, methods of analysis and dietary differences can affect trophic shift for consumers; the utility of stable isotope methods can be improved if this information is incorporated into studies of trophic relationships. Although few studies of stable isotope ratios have considered variation in the trophic shift, such variation is important because small errors in estimates of trophic shift can result in large errors in estimates of the contribution of sources to consumers or in estimates of trophic position.

  18. Evolutionarily stable strategy of carbon and nitrogen investments in forest leaves and its application in vegetation dynamic modeling

    NASA Astrophysics Data System (ADS)

    Weng, E.; Farrior, C.; Dybzinski, R.; Pacala, S. W.

    2015-12-01

    Leaf mass per area (LMA) and leaf lifespan (LL) are two highly correlated plant traits that are key to plant physiological and ecological properties. Usually, low LMA means short LL, high nitrogen (N) content per unit mass, and fast turnover rates of nutrients; high LMA leads to long LL, low N content, and slow turnover rates. Deciduous trees with low LMA and short lifespan leaves have low carbon cost but high nitrogen demand; and evergreen trees, with high LMA and long lifespan leaves, have high carbon cost but low nitrogen demand. These relationships lead to: 1) evergreen trees have higher leaf area index than deciduous trees; 2) evergreen trees' carbon use efficiency is lower than the deciduous trees' because of their thick leaves and therefore high maintenance respiration; 3) the advantage of evergreens trees brought by their extra leaves over deciduous trees diminishes with increase N in ecosystem. These facts determine who will win when trees compete with each other in a N-limited ecosystem. In this study, we formulate a mathematical model according to the relationships between LMA, LL, leaf nitrogen, and leaf building and maintenance cost, where LMA is the fundamental variable determining the other three. We analyze the evolutionarily stable strategies (ESSs) of LMA with this mathematical model by examining the benefits of carbon and nitrogen investments to leaves in ecosystems with different N. The model shows the ESS converges to low LMA at high N and high LMA at low N. At intermediate N, there are two ESSs at low and high ends of LMA, respectively. The ESS also leads to low forest productivity by outcompeting the possible high productive strategies. We design a simulation scheme in an individual-based competition model (LM3-PPA) to simulate forest dynamics as results of the competition between deciduous and evergreen trees in three different biomes, which are temperate deciduous forest, deciduous-evergreen mixed forest, and boreal evergreen forest. The

  19. Using semi-permeable membrane devices and stable nitrogen isotopes to detect anthropogenic influences on the Truckee River, USA

    USGS Publications Warehouse

    Saito, L.; Rosen, Michael R.; Chandra, S.; Fritsen, C.H.; Arufe, J.A.; Redd, C.

    2008-01-01

    Stable nitrogen isotopes (??15N) and semipermeable membrane devices (SPMDs) were used together to provide evidence of potential anthropogenic connections to aquatic organisms in the Truckee River, which flows through the Reno/Sparks metropolitan area in Nevada. Crayfish, snail, and periphyton ??15N values, and SPMD toxicity data collected during high and low flow periods at seven primary sites on the river were used with water quality and flow data for the assessment. All biota showed an increase of ??15N on both dates at sites downstream of inflows of a water-quality impaired tributary and urban drain relative to upstream. In addition, most of the lowest ??15N values on each date occurred at the most downstream site on the river. SPMDs sample lipophilic organic contaminants and can be used to assess organic contaminant toxicity to aquatic organisms because they use a membrane that mimics organic contaminant uptake by fish. In this study, results from a fluoroscan test [pyrene index (PI)] of SPMD extracts that responds to higher molecular weight polycyclic aromatic hydrocarbons (PAHs) showed patterns similar to stable isotope data, although observed peaks in PI values occurred in the urban area upstream of where peak ??15N values occurred. The CYP1A biomarker test, which responds to PAHs, certain polychlorinated biphenyls (PCBs), and organochlorines, showed peak toxic equivalents (TEQ) values farther downstream of the urban area. Thus, it is likely that PAHs were contributing to toxicity in the urban area, whereas other nonurban sources of organic carbon may have been present farther downstream. The combined use of stable isotope measurements and SPMDs provided a means of simultaneously examining whether aquatic biota are incorporating constituents from potential food sources (via stable isotopes) or exposure through water (via SPMDs). ?? Mary Ann Liebert, Inc. 2008.

  20. Stable nitrogen isotopic composition of amino acids reveals food web structure in stream ecosystems.

    PubMed

    Ishikawa, Naoto F; Kato, Yoshikazu; Togashi, Hiroyuki; Yoshimura, Mayumi; Yoshimizu, Chikage; Okuda, Noboru; Tayasu, Ichiro

    2014-07-01

    The stable N isotopic composition of individual amino acids (SIAA) has recently been used to estimate trophic positions (TPs) of animals in several simple food chain systems. However, it is unknown whether the SIAA is applicable to more complex food web analysis. In this study we measured the SIAA of stream macroinvertebrates, fishes, and their potential food sources (periphyton and leaf litter of terrestrial C3 plants) collected from upper and lower sites in two streams having contrasting riparian landscapes. The stable N isotope ratios of glutamic acid and phenylalanine confirmed that for primary producers (periphyton and C3 litter) the TP was 1, and for primary consumers (e.g., mayfly and caddisfly larvae) it was 2. We built a two-source mixing model to estimate the relative contributions of aquatic and terrestrial sources to secondary and higher consumers (e.g., stonefly larva and fishes) prior to the TP calculation. The estimated TPs (2.3-3.5) roughly corresponded to their omnivorous and carnivorous feeding habits, respectively. We found that the SIAA method offers substantial advantages over traditional bulk method for food web analysis because it defines the food web structure based on the metabolic pathway of amino groups, and can be used to estimate food web structure under conditions where the bulk method cannot be used. Our result provides evidence that the SIAA method is applicable to the analysis of complex food webs, where heterogeneous resources are mixed.

  1. Use of stable carbon and nitrogen isotope ratios in size segregated aerosol particles for the O/I penetration evaluation

    NASA Astrophysics Data System (ADS)

    Garbaras, Andrius; Garbariene, Inga; Masalaite, Agne; Ceburnis, Darius; Krugly, Edvinas; Kvietkus, Kestutis; Remeikis, Vidmantas; Martuzevicius, Dainius

    2015-04-01

    Stable carbon and nitrogen isotope ratio are successfully used in the atmospheric aerosol particle source identification [1, 2], transformation, pollution [3] research. The main purpose of this study was to evaluate the penetration of atmospheric aerosol particles from outdoor to indoor using stable carbon and nitrogen isotope ratios. Six houses in Kaunas (Lithuania) were investigated during February and March 2013. Electrical low pressure impactor was used to measure in real time concentration and size distribution of outdoor aerosol particles. ELPI+ includes 15 channels covering the size range from 0.017 to 10.0 µm. The 25 mm diameter aluminium foils were used to collect aerosol particles. Gravimetric analysis of samples was made using microbalance. In parallel, indoor aerosol samples were collected with a micro-orifice uniform deposition impactor (MOUDI model 110), where the aerosol particles were separated with the nominal D50 cut-off sizes of 0.056, 0.1, 0.18,0.32,0.56, 1.0, 1.8, 3.2, 5.6, 10, 18 μm for impactor stages 1-11, respectively. The impactor was run at a flow rate of 30 L/min. Air quality meters were used to record meteorological conditions (temperature, relative humidity) during the investigated period. All aerosol samples were analyzed for total carbon (TC) and total nitrogen (TN) contents and their isotopic compositions using elemental analyzer (EA) connected to the stable isotope ratio mass spectrometer (IRMS). TC concentration in indoors ranged from 1.5 to 247.5 µg/m3. During the sampling period outdoors TN levels ranged from 0.1 to 10.9 µg/m3. The obtained outdoor δ13C(PM2.5) values varied from -24.21 to -26.3‰, while the δ15N values varied from 2.4 to 11.1 ‰ (average 7.2±2.5 ‰). Indoors carbonaceous aerosol particles were depleted in 13C compared to outdoors in all sampling sites. This depletion in δ13C varied from 0.1 to 3.2 ‰. We think that this depletion occurs due ongoing chemical reactions (oxidation) when aerosol

  2. Regional nitrogen dynamics in the TERENO Bode River catchment, Germany, as constrained by stable isotope patterns.

    PubMed

    Mueller, Christin; Krieg, Ronald; Merz, Ralf; Knöller, Kay

    2016-01-01

    Interactions between hydrological characteristics and microbial activities affect the isotopic composition of dissolved nitrate in surface water. Nitrogen and oxygen isotopic signatures of riverine nitrate in 133 sampling locations distributed over the Bode River catchment in the Harz Mountains, Germany, were used to identify nitrate sources and transformation processes. An annual monitoring programme consisting of seasonal sampling campaigns in spring, summer and autumn was conducted. δ(15)N and δ(18)O of nitrate and corresponding concentrations were measured as well as δ(2)H and δ(18)O of water to determine the deuterium excess. In addition, precipitation on 25 sampling stations was sampled and considered as a potential input factor. The Bode River catchment is strongly influenced by agricultural land use which is about 70 % of the overall size of the catchment. Different nitrogen sources such as ammonia (NH4) fertilizer, soil nitrogen, organic fertilizer or nitrate in precipitation show partly clear nitrate isotopic differences. Processes such as microbial denitrification result in fractionation and lead to an increase in δ(15)N of nitrate. We observed an evident regional and partly temporal variation of nitrate isotope signatures which are clearly different between main landscape types. Spring water sections within the high mountains contain nitrate in low concentrations with low δ(15)NNO3 values of -3 ‰ and high δ(18)ONO3 values up to 13 ‰. High mountain stream water sub-catchments dominated by nearly undisturbed forest and grassland contribute nitrate with δ(15)NNO3 and δ(18)ONO3 values of -1 and -3.5 ‰, respectively. In the further flow path, which is affected by an increasing agricultural land use and urban sewage, we recognized an increase in δ(15)NNO3 and δ(18)ONO3 up to 22 and 18 ‰, respectively, with high variations during the year. A correlation seems to exist between the percentage of agricultural land use area and the

  3. Trophic Discrimination Factors and Incorporation Rates of Carbon- and Nitrogen-Stable Isotopes in Adult Green Frogs, Lithobates clamitans.

    PubMed

    Cloyed, Carl S; Newsome, Seth D; Eason, Perri K

    2015-01-01

    Stable isotope analysis is an increasingly useful ecological tool, but its accuracy depends on quantifying the tissue-specific trophic discrimination factors (TDFs) and isotopic incorporation rates for focal taxa. Despite the technique's ubiquity, most laboratory experiments determining TDFs and incorporation rates have focused on birds, mammals, and fish; we know little about terrestrial ectotherms, and amphibians in particular are understudied. In this study we used two controlled feeding experiments to determine carbon (δ(13)C) and nitrogen (δ(15)N) isotope TDFs for skin, whole blood, and bone collagen and incorporation rates for skin and whole blood in adult green frogs, Lithobates clamitans. The mean (±SD) TDFs for δ(13)C were 0.1‰ (±0.4‰) for skin, 0.5‰ (±0.5‰) for whole blood, and 1.6‰ (0.6‰) for bone collagen. The mean (±SD) TDFs for δ(15)N were 2.3‰ (±0.5‰) for skin, 2.3‰ (±0.4‰) for whole blood, and 3.1‰ (±0.6‰) for bone collagen. A combination of different isotopic incorporation models was best supported by our data. Carbon in skin was the only tissue in which incorporation was best explained by two compartments, which had half-lives of 89 and 8 d. The half-life of carbon in whole blood was 69 d. Half-lives for nitrogen were 75 d for skin and 71 d for whole blood. Our results help fill a taxonomic gap in our knowledge of stable isotope dynamics and provide ecologists with a method to measure anuran diets.

  4. Effects of acidification, lipid removal and mathematical normalization on carbon and nitrogen stable isotope compositions in beaked whale (Ziphiidae) bone.

    PubMed

    Tatsch, Ana Carolina C; Secchi, Eduardo R; Botta, Silvina

    2016-02-15

    The analysis of stable isotopes in tissues such as teeth and bones has been used to study long-term trophic ecology and habitat use in marine mammals. However, carbon isotope ratios (δ(13) C values) can be altered by the presence of (12) C-rich lipids and carbonates. Lipid extraction and acidification are common treatments used to remove these compounds. The impact of lipids and carbonates on carbon and nitrogen isotope ratios (δ(15) N values), however, varies among tissues and/or species, requiring taxon-specific protocols to be developed. The effects of lipid extraction and acidification and their interaction on carbon and nitrogen isotope values were studied for beaked whale (Ziphiidae) bone samples. δ(13) C and δ(15) N values were determined in quadruplicate samples: control, lipid-extracted, acidified and lipid-extracted followed by acidification. Samples were analyzed by means of elemental analysis isotope ratio mass spectrometry. Furthermore, the efficiency of five mathematical models developed for estimating lipid-normalized δ(13) C values from untreated δ(13) C values was tested. Significant increases in δ(13) C values were observed after lipid extraction. No significant changes in δ(13) C values were found in acidified samples. An interaction between both treatments was demonstrated for δ(13) C but not for δ(15) N values. No change was observed in δ(15) N values for lipid-extracted and/or acidified samples. Although all tested models presented good predictive power to estimate lipid-free δ(13) C values, linear models performed best. Given the observed changes in δ(13) C values after lipid extraction, we recommend a priori lipid extraction or a posteriori lipid normalization, through simple linear models, for beaked whale bones. Furthermore, acidification seems to be an unnecessary step before stable isotope analysis, at least for bone samples of ziphiids. Copyright © 2015 John Wiley & Sons, Ltd. Copyright © 2015 John Wiley & Sons, Ltd.

  5. Constraining the Biological Pump using Stable Nitrogen and Carbon Isotopes in the Glacial Ocean

    NASA Astrophysics Data System (ADS)

    Somes, C. J.; Schmittner, A.

    2010-12-01

    An increase in the strength of the biological pump during the last glacial maximum (LGM) relative to modern times may have significantly contributed to the deglacial rise in atmospheric CO2. As phytoplankton grow, they consume CO2 out of the surface ocean and atmosphere then transport it to the deep ocean and sea floor sediments through their sinking detrital matter, where it can remain for a long time. Two of the most important limiting nutrients for phytoplankton growth are fixed nitrogen (N) and iron (Fe). The ocean fixed-N inventory in controlled by the balance between denitrification, which occurs under suboxic conditions (O2 < 5 uM) in the water column and sea floor sediments, and N2 fixation, which occurs when specialized prokaryotes fix atmospheric N2 to meet their N requirement when fixed N is fully depleted at surface. N2-fixers also have relatively high Fe requirements that can limit their growth and ability to balance the N-loss from denitrification. Sediment and ice core records suggests that the ocean inventory of both fixed N and Fe may have been significantly higher during the last glacial maximum (LGM) relative to modern times. A colder, more well-oxygenated ocean would have likely reduced denitrification, which is consistent with a decrease in δ15N in present-day water column denitrification zones. Dust in ice core records also show massive spikes during the LGM that could reduce the extent of HNLC zones and stimulate more export production. We present a global Earth System Climate Model that includes both nitrogen (14N and 15N) and carbon (12C and 13C) isotopes that is run with LGM boundary conditions. Preliminary sensitivity experiments that include a parameterization for the effect of Fe on diazotroph and diatom growth, which are based on atmospheric dust deposition estimates are shown. Fe limitation of diazotrophy reduces the tight coupling of denitrification and N2 fixation and allows the global N inventory to increase by more than 5% during

  6. Use of sulfur and nitrogen stable isotopes to determine the importance of whitebark pine nuts to Yellowstone grizzly bears

    USGS Publications Warehouse

    Felicetti, L.A.; Schwartz, C.C.; Rye, R.O.; Haroldson, M.A.; Gunther, K.A.; Phillips, D.L.; Robbins, C.T.

    2003-01-01

    Whitebark pine (Pinus albicaulis) is a masting species that produces relatively large, fat- and protein-rich nuts that are consumed by grizzly bears (Ursus arctos horribilis). Trees produce abundant nut crops in some years and poor crops in other years. Grizzly bear survival in the Greater Yellowstone Ecosystem is strongly linked to variation in pine-nut availability. Because whitebark pine trees are infected with blister rust (Cronartium ribicola), an exotic fungus that has killed the species throughout much of its range in the northern Rocky Mountains, we used stable isotopes to quantify the importance of this food resource to Yellowstone grizzly bears while healthy populations of the trees still exist. Whitebark pine nuts have a sulfur-isotope signature (9.2 ?? 1.3??? (mean ?? 1 SD)) that is distinctly different from those of all other grizzly bear foods (ranging from 1.9 ?? 1.7??? for all other plants to 3.1 ?? 2.6??? for ungulates). Feeding trials with captive grizzly bears were used to develop relationships between dietary sulfur-, carbon-, and nitrogen-isotope signatures and those of bear plasma. The sulfur and nitrogen relationships were used to estimate the importance of pine nuts to free-ranging grizzly bears from blood and hair samples collected between 1994 and 2001. During years of poor pine-nut availability, 72% of the bears made minimal use of pine nuts. During years of abundant cone availability, 8 ?? 10% of the bears made minimal use of pine nuts, while 67 ?? 19% derived over 51% of their assimilated sulfur and nitrogen (i.e., protein) from pine nuts. Pine nuts and meat are two critically important food resources for Yellowstone grizzly bears.

  7. Intraclade Heterogeneity in Nitrogen Utilization by Marine Prokaryotes Revealed Using Stable Isotope Probing Coupled with Tag Sequencing (Tag-SIP).

    PubMed

    Morando, Michael; Capone, Douglas G

    2016-01-01

    Nitrogen can greatly influence the structure and productivity of microbial communities through its relative availability and form. However, the roles of specific organisms in the uptake of different nitrogen species remain poorly characterized. Most studies seeking to identify agents of assimilation have been correlative, indirectly linking activity measurements (e.g., nitrate uptake) with the presence or absence of biological markers, particularly functional genes and their transcripts. Evidence is accumulating of previously underappreciated functional diversity in major microbial subpopulations, which may confer physiological advantages under certain environmental conditions leading to ecotype divergence. This microdiversity further complicates our view of genetic variation in environmental samples requiring the development of more targeted approaches. Here, next-generation tag sequencing was successfully coupled with stable isotope probing (Tag-SIP) to assess the ability of individual phylotypes to assimilate a specific N source. Our results provide the first direct evidence of nitrate utilization by organisms thought to lack the genes required for this process including the heterotrophic clades SAR11 and the Archaeal Marine Group II. Alternatively, this may suggest the existence of tightly coupled metabolisms with primary assimilators, e.g., symbiosis, or the rapid and efficient scavenging of recently released products by highly active individuals. These results may be connected with global dominance often seen with these clades, likely conferring an advantage over other clades unable to access these resources. We also provide new direct evidence of in situ nitrate utilization by the cyanobacterium Prochlorococcus in support of recent findings. Furthermore, these results revealed widespread functional heterogeneity, i.e., different levels of nitrogen assimilation within clades, likely reflecting niche partitioning by ecotypes.

  8. Intraclade Heterogeneity in Nitrogen Utilization by Marine Prokaryotes Revealed Using Stable Isotope Probing Coupled with Tag Sequencing (Tag-SIP)

    PubMed Central

    Morando, Michael; Capone, Douglas G.

    2016-01-01

    Nitrogen can greatly influence the structure and productivity of microbial communities through its relative availability and form. However, the roles of specific organisms in the uptake of different nitrogen species remain poorly characterized. Most studies seeking to identify agents of assimilation have been correlative, indirectly linking activity measurements (e.g., nitrate uptake) with the presence or absence of biological markers, particularly functional genes and their transcripts. Evidence is accumulating of previously underappreciated functional diversity in major microbial subpopulations, which may confer physiological advantages under certain environmental conditions leading to ecotype divergence. This microdiversity further complicates our view of genetic variation in environmental samples requiring the development of more targeted approaches. Here, next-generation tag sequencing was successfully coupled with stable isotope probing (Tag-SIP) to assess the ability of individual phylotypes to assimilate a specific N source. Our results provide the first direct evidence of nitrate utilization by organisms thought to lack the genes required for this process including the heterotrophic clades SAR11 and the Archaeal Marine Group II. Alternatively, this may suggest the existence of tightly coupled metabolisms with primary assimilators, e.g., symbiosis, or the rapid and efficient scavenging of recently released products by highly active individuals. These results may be connected with global dominance often seen with these clades, likely conferring an advantage over other clades unable to access these resources. We also provide new direct evidence of in situ nitrate utilization by the cyanobacterium Prochlorococcus in support of recent findings. Furthermore, these results revealed widespread functional heterogeneity, i.e., different levels of nitrogen assimilation within clades, likely reflecting niche partitioning by ecotypes. PMID:27994576

  9. Stable isotopes as a tool for nitrogen source identification and cycling in the Gulf of Trieste (Northern Adriatic)

    NASA Astrophysics Data System (ADS)

    Tamše, Samo; Mozetič, Patricija; Francé, Janja; Ogrinc, Nives

    2014-12-01

    Nitrogen concentrations and isotopic composition were used to identify nitrate sources and processes in the catchments of two Slovenian coastal rivers, Rižana and Dragonja, and to investigate whether they have any notable influence on the Gulf of Trieste. The sampling was performed from May 2010 to March 2011. The data indicated that δ15NNO3 values in rivers provided mainly information about sources of riverine nitrate derived from soil nitrification, sewage, and/or manure. The load weighted δ15NNO3 values of 4.3‰ and 9.4‰ determined at the mouth of Rižana and Dragonja, respectively, were largely controlled by land-use in the riverine catchment. Phytoplankton nitrate assimilation was found to be significant mainly at the mouth of Dragonja. The combined use of salinity, nutrient concentrations, and nitrate, particulate nitrogen and carbon isotopic compositions revealed that the seawater surface was influenced by mixing with different sources including seawater, rivers and sewage effluent. The site influenced by sewage effluent is relatively spatially isolated, which suggests that NO3 - is not widely distributed by this point source. Besides mixing, phytoplankton uptake was the main process controlling the distribution and isotopic composition of NO3 - in the marine system and was more extensive in spring 2010, while in autumn NH4 +, not NO3 -, was the dominant source of N for phytoplankton. In addition, our results are consistent with the occurrence of nitrification in the water column in autumn and winter. The nitrification activity was higher in autumn, while in winter it occurred in parallel to phytoplankton uptake. This study demonstrates how stable isotopes of nitrogen in nitrate along with concentration measurements can be relevant when trying to identify the sources and key processes such as assimilation and nitrification in rivers and coastal areas.

  10. Recovery of nitrogen stable isotope signatures in the food web of an intermittently open estuary following removal of wastewater loads

    NASA Astrophysics Data System (ADS)

    Smith, Phoebe E.; Oakes, Joanne M.; Eyre, Bradley D.

    2016-12-01

    Nitrogen (N) stable isotope values (δ15N) were used to assess the removal of wastewater N from the food web within Tallow Creek, a small intermittently closed/open lake/lagoon (ICOLL) on the east coast of Australia, following the cessation of wastewater inputs in 2005. Current (2013) δ15N values of sediment organic carbon, plants, and animals within Tallow Creek were compared to values obtained before wastewater inputs ceased, and to values within a nearby near-pristine ICOLL (Jerusalem Creek). Most biota had significantly depleted δ15N values compared to conspecifics collected before wastewater inputs ceased (mean reduction of 6.0‰; 38% of impacted enrichment), indicating substantial loss of wastewater N since inputs ceased. However, δ15N values remained enriched compared to the near-pristine ICOLL for some components (mean enrichment of 3.3‰ or 38%), suggesting that some wastewater N remains. The δ15N recovery rate (decrease in δ15N as a percentage of the impacted enrichment) for Tallow Creek biota was slow compared to that of biota in more open systems. This slow recovery rate and the persistence of some wastewater N, even after 8 years without new inputs, reflects differences in hydrology and nitrogen cycling between permanently open and intermittently open estuarine systems and highlights the likely lower resilience of ICOLLs to anthropogenic N inputs.

  11. Stable nitrogen isotope studies of the pelagic food web on the Atlantic shelf of the Iberian Peninsula

    NASA Astrophysics Data System (ADS)

    Bode, Antonio; Alvarez-Ossorio, M. Teresa; Cunha, M. Emilia; Garrido, Susana; Peleteiro, J. Benito; Porteiro, Carmela; Valdés, Luis; Varela, Manuel

    2007-08-01

    The structure and variability of pelagic food webs along the north and northwestern shelf of the Iberian Peninsula were analysed using natural abundance of nitrogen stable isotopes of plankton and pelagic consumers. Plankton composition was mainly studied in size-fractionated samples, but also the isotopic signatures of three copepod species, as representative of primary consumers, were considered. Several fish species were included as planktivorous consumers, with special attention to sardine ( Sardina pilchardus). Finally, top pelagic consumers were represented by the common dolphin ( Delphinus delphis). The relationship between trophic position and body size implies large variability in the ratio of predator to prey sizes, likely because widespread omnivory and plankton consumption by relatively large predators. Planktivorous species share a common trophic position, suggesting potential competition for food, and low nitrogen isotope enrichment between prey and consumers suggest nutrient limitation and recycling at the base of the food web. Both experimental and field evidences indicate that the muscle of sardine integrates fish diet over seasonal periods and reflects the composition of plankton from large shelf areas. The low mobility of sardines during periods of low population size is consistent with differential isotopic signatures found in shelf zones characterised by upwelling nutrient inputs.

  12. Stable isotope profiles of nitrogen gas indicate denitrification in oxygen-stratified humic lakes.

    PubMed

    Tiirola, Marja A; Rissanen, Antti J; Sarpakunnas, Miika; Arvola, Lauri; Nykänen, Hannu

    2011-06-15

    Mid-summer N(2) profiles were analyzed from nine oxygen-stratified, humic-acid-rich lakes using a continuous flow isotope ratio mass spectrometer and a Gasbench II device. Sample preparation steps were performed under water to avoid air contamination. The instrument precision for the δ(15)N measurement was high (0.03‰), but for the whole sampling and analysis procedure the mean deviation between replicate samples was 0.13‰ for the δ(15)N measurements and 5.5% for the N(2) gas concentration analysis. The results show that the Gasbench peripheral was suitable for measurement of the (15)N natural abundance of dissolved nitrogen gas, with denitrification indicated by the oversaturation and slightly (<1‰) depleted δ(15)N values of the dissolved N(2) gas in the suboxic zones of some of the study lakes. Calculated values for the denitrified (excess) N(2) varied between -5.3 and 0.7‰. The denitrification potential was determined using the (15)N tracer method, with results showing nitrate-inducible denitrification and no signs of anaerobic ammonium oxidation (anammox). Copyright © 2011 John Wiley & Sons, Ltd.

  13. Using stable isotopes to assess carbon and nitrogen turnover in the Arctic sympagic amphipod Onisimus litoralis.

    PubMed

    Kaufman, Mette R; Gradinger, Rolf R; Bluhm, Bodil A; O'Brien, Diane M

    2008-11-01

    Food web studies based on stable C and N isotope ratios usually assume isotopic equilibrium between a consumer and its diet. In the Arctic, strong seasonality in food availability often leads to diet switching, resulting in a consumer's isotopic composition to be in flux between different food sources. Experimental work investigating the time course and dynamics of isotopic change in Arctic fauna has been lacking, although these data are crucial for accurate interpretation of food web relationships. We investigated seasonal (ice-covered spring vs. ice-free summer) and temperature (1 vs. 4 degrees C) effects on growth and stable C and N isotopic change in the common nearshore Arctic amphipod Onisimus litoralis following a diet switch and while fasting in the laboratory. In spring we found no significant temperature effect on N turnover [half-life (HL) estimates: HL-N = 20.4 at 4 degrees C, 22.4 days at 1 degrees C] and a nonsignificant trend for faster growth and C turnover at the higher temperature (HL-C = 13.9 at 4 degrees C, 18.7 days at 1 degrees C). A strong seasonal effect was found, with significantly slower growth and C and N turnover in the ice-free summer period (HL-N = 115.5 days, HL-C = 77.0 days). Contrary to previous studies, metabolic processes rather than growth accounted for most of the change in C and N isotopic composition (84-89 and 67-77%, respectively). This study provides the first isotopic change and metabolic turnover rates for an Arctic marine invertebrate and demonstrates the risk of generalizing turnover rates based on taxon, physiology, and environment. Our results highlight the importance of experimental work to determine turnover rates for species of interest.

  14. Stable nitrogen isotopes of nestling tree swallows indicate exposure to different types of oil sands reclamation.

    PubMed

    Farwell, A J; Harms, N J; Smits, J E G; Dixon, D G

    2014-01-01

    Tree swallows (Tachycineta bicolor) inhabiting reclaimed wetlands on the oil sands in northern Alberta are potentially exposed to elevated levels of oil sands constituents such as polycyclic aromatic compounds (PAC) through diet. While increased detoxification enzyme activity as measured using 7-ethoxyresorufin O-deethylase in nestlings is a generally accepted indicator of exposure to oil sands constituents, there is no apparent method to detect dietary exposure specific to oil sands processed material (OSPM). In this study, stable C and N isotopes were analyzed from muscle and feathers of nestling tree swallows (15 d old) to distinguish dietary exposure of birds near reference and OSPM wetlands. High δ¹⁵N and low δ¹³C values in the nestling tissues differentiated those from the OSPM wetlands and reference sites. Lower δ¹⁵N values of nestlings compared to the δ¹⁵N values of larval chironomids from an earlier study suggested that the majority of the diet of the nestlings was derived from non-OSPM sources, despite residence near and on the OSPM wetlands. Our finding of limited utilization of OSPM resources by tree swallows indicates either low abundance or diversity of dietary items emerging from OSPM wetlands, or sensory avoidance of prey from those wetlands. Minimal consumption of OSPM-derived dietary sources may be attributed to published findings of limited adverse effects on tree swallow reproduction, or growth and development for these same nestlings. This study demonstrated that stable isotope analysis, particularly for N isotopes, may serve as a useful tool to trace dietary exposure to OSPM constituents as part of avian ecotoxicology assessments of reclaimed wetlands on the oil sands.

  15. [Meta-analysis of stable carbon and nitrogen isotopic enrichment factors for aquatic animals].

    PubMed

    Guo, Liang; Sun, Cui-ping; Ren, Wei-zheng; Zhang, Jian; Tang, Jian-iun; Hu, Liana-liang; Chen, Xin

    2016-02-01

    Isotopic enrichment factor (Δ, the difference between the δ value of food and a consumer tissue) is an important parameter in using stable isotope analysis (SIA) to reconstruct diets, characterize trophic relationships, elucidate patterns of resource allocation, and construct food webs. Isotopic enrichment factor has been considered as a constancy value across a broad range of animals. However, recent studies showed that the isotopic enrichment factor differed among various types of animals although the magnitude of variation was not clear. Here, we conducted a meta-analysis to synthesize and compare Δ13C and Δ15N among four types of aquatic animals (teleosts, crustaceans, reptiles and molluscs). We searched for papers published before 2014 on Web of Science and CNKI using the key words "stable isotope or isotopic fractionation or fractionation factor or isotopic enrichment or trophic enrichment". Forty-two publications that contain 140 studies on Δ13C and 159 studies on Δ15N were obtained. We conducted three parallel meta-analyses by using three types of weights (the reciprocal of variance as weights, the sample size as weights, and equal weights). The results showed that no significant difference in Δ13C among different animal types (teleosts 1.0 per thousand, crustaceans 1.3 per thousand, reptiles 0.5 per thousand, and molluscs 1.5 per thousand), while Δ15N values were significantly different (teleosts 2.4 per thousand, crustaceans 3.6 per thousand, reptiles 1.0 per thousand and molluscs 2.5 per thousand). Our results suggested that the overall mean of Δ13C could be used as a general enrichment factor, but Δ15N should be chosen according to the type of aquatic animals in using SIA to analyze trophic relationships, patterns of resource allocation and food webs.

  16. Temporal variation in mycorrhizal diversity and carbon and nitrogen stable isotope abundance in the wintergreen meadow orchid Anacamptis morio.

    PubMed

    Ercole, Enrico; Adamo, Martino; Rodda, Michele; Gebauer, Gerhard; Girlanda, Mariangela; Perotto, Silvia

    2015-02-01

    Many adult orchids, especially photoautotrophic species, associate with a diverse range of mycorrhizal fungi, but little is known about the temporal changes that might occur in the diversity and functioning of orchid mycorrhiza during vegetative and reproductive plant growth. Temporal variations in the spectrum of mycorrhizal fungi and in stable isotope natural abundance were investigated in adult plants of Anacamptis morio, a wintergreen meadow orchid. Anacamptis morio associated with mycorrhizal fungi belonging to Tulasnella, Ceratobasidium and a clade of Pezizaceae (Ascomycetes). When a complete growing season was investigated, multivariate analyses indicated significant differences in the mycorrhizal fungal community. Among fungi identified from manually isolated pelotons, Tulasnella was more common in autumn and winter, the pezizacean clade was very frequent in spring, and Ceratobasidium was more frequent in summer. By contrast, relatively small variations were found in carbon (C) and nitrogen (N) stable isotope natural abundance, A. morio samples showing similar (15)N enrichment and (13)C depletion at the different sampling times. These observations suggest that, irrespective of differences in the seasonal environmental conditions, the plant phenological stages and the associated fungi, the isotopic content in mycorrhizal A. morio remains fairly constant over time.

  17. Trophic Relationships and Habitat Preferences of Delphinids from the Southeastern Brazilian Coast Determined by Carbon and Nitrogen Stable Isotope Composition

    PubMed Central

    Bisi, Tatiana Lemos; Dorneles, Paulo Renato; Lailson-Brito, José; Lepoint, Gilles; Azevedo, Alexandre de Freitas; Flach, Leonardo; Malm, Olaf; Das, Krishna

    2013-01-01

    To investigate the foraging habitats of delphinids in southeastern Brazil, we analyzed stable carbon (δ13C) and nitrogen (δ15N) isotopes in muscle samples of the following 10 delphinid species: Sotalia guianensis, Stenella frontalis, Tursiops truncatus, Steno bredanensis, Pseudorca crassidens, Delphinus sp., Lagenodelphis hosei, Stenella attenuata, Stenella longirostris and Grampus griseus. We also compared the δ13C and δ15N values among four populations of S. guianensis. Variation in carbon isotope results from coast to ocean indicated that there was a significant decrease in δ13C values from estuarine dolphins to oceanic species. S. guianensis from Guanabara Bay had the highest mean δ13C value, while oceanic species showed significantly lower δ13C values. The highest δ15N values were observed for P. crassidens and T. truncatus, suggesting that these species occupy the highest trophic position among the delphinids studied here. The oceanic species S. attenuata, G. griseus and L. hosei had the lowest δ15N values. Stable isotope analysis showed that the three populations of S. guianensis in coastal bays had different δ13C values, but similar δ15N results. Guiana dolphins from Sepetiba and Ilha Grande bays had different foraging habitat, with specimens from Ilha Grande showing more negative δ13C values. This study provides further information on the feeding ecology of delphinids occurring in southeastern Brazil, with evidence of distinctive foraging habitats and the occupation of different ecological niches by these species in the study area. PMID:24358155

  18. Trace Elements and Carbon and Nitrogen Stable Isotopes in Organisms from a Tropical Coastal Lagoon

    PubMed Central

    van Hattum, B.; de Boer, J.; van Bodegom, P. M.; Rezende, C. E.; Salomons, W.

    2010-01-01

    Trace elements (Fe, Mn, Al, Zn, Cr, Cu, Ni, Pb, Cd, Hg, and As) and stable isotope ratios (δ13C and δ15N) were analyzed in sediments, invertebrates, and fishes from a tropical coastal lagoon influenced by iron ore mining and processing activities to assess the differences in trace element accumulation patterns among species and to investigate relations with trophic levels of the organisms involved. Overall significant negative relations between trophic level (given by 15N) and trace element concentrations in gastropods and crustaceans showed differences in internal controls of trace element accumulation among the species of different trophic positions, leading to trace element dilution. Generally, no significant relation between δ15N and trace element concentrations was observed among fish species, probably due to omnivory in a number of species as well as fast growth. Trace element accumulation was observed in the fish tissues, with higher levels of most trace elements found in liver compared with muscle and gill. Levels of Fe, Mn, Al, and Hg in invertebrates, and Fe and Cu in fish livers, were comparable with levels in organisms and tissues from other contaminated areas. Trace element levels in fish muscle were below the international safety baseline standards for human consumption. PMID:20217062

  19. 15 N- and 2 H proteomic stable isotope probing links nitrogen flow to archaeal heterotrophic activity

    SciTech Connect

    Justice, Nicholas B.; Li, Zhou; Wang, Yingfeng; Spaulding, Susan E.; Mosier, Annika C.; Robert L. Hettich; Pan, Chongle; Banfield, Jillian F.

    2014-05-20

    Understanding how individual species contribute to nutrient transformations in a microbial community is critical to prediction of overall ecosystem function. We conducted microcosm experiments in which floating acid mine drainage (AMD) microbial biofilms were submerged recapitulating the final stage in a natural biofilm life cycle. Biofilms were amended with either 15NH4 + or deuterium oxide (2H2O) and proteomic stable isotope probing (SIP) was used to track the extent to which different members of the community used these molecules in protein synthesis across anaerobic iron-reducing, aerobic iron-reducing and aerobic iron-oxidizing environments. Sulfobacillus spp. synthesized 15N-enriched protein almost exclusively under iron-reducing conditions whereas the Leptospirillum spp. synthesized 15N-enriched protein in all conditions. There were relatively few 15Nenriched archaeal proteins, and all showed low atom% enrichment, consistent with Archaea synthesizing protein using the predominantly 14N biomass derived from recycled biomolecules. In parallel experiments using 2H2O, extensive archaeal protein synthesis was detected in all conditions. In contrast, the bacterial species showed little protein synthesis using 2H2O. The nearly exclusive ability of Archaea to synthesize proteins using 2H2O may be due to archaeal heterotrophy, whereby Archaea off set deleterious effects of 2H by accessing 1H generated byrespiration of organic compounds.

  20. Trace elements and carbon and nitrogen stable isotopes in organisms from a tropical coastal lagoon.

    PubMed

    Pereira, A A; van Hattum, B; de Boer, J; van Bodegom, P M; Rezende, C E; Salomons, W

    2010-10-01

    Trace elements (Fe, Mn, Al, Zn, Cr, Cu, Ni, Pb, Cd, Hg, and As) and stable isotope ratios (delta(13)C and delta(15)N) were analyzed in sediments, invertebrates, and fishes from a tropical coastal lagoon influenced by iron ore mining and processing activities to assess the differences in trace element accumulation patterns among species and to investigate relations with trophic levels of the organisms involved. Overall significant negative relations between trophic level (given by (15)N) and trace element concentrations in gastropods and crustaceans showed differences in internal controls of trace element accumulation among the species of different trophic positions, leading to trace element dilution. Generally, no significant relation between delta(15)N and trace element concentrations was observed among fish species, probably due to omnivory in a number of species as well as fast growth. Trace element accumulation was observed in the fish tissues, with higher levels of most trace elements found in liver compared with muscle and gill. Levels of Fe, Mn, Al, and Hg in invertebrates, and Fe and Cu in fish livers, were comparable with levels in organisms and tissues from other contaminated areas. Trace element levels in fish muscle were below the international safety baseline standards for human consumption.

  1. (15)N- and (2)H proteomic stable isotope probing links nitrogen flow to archaeal heterotrophic activity.

    PubMed

    Justice, Nicholas B; Li, Zhou; Wang, Yingfeng; Spaudling, Susan E; Mosier, Annika C; Hettich, Robert L; Pan, Chongle; Banfield, Jillian F

    2014-10-01

    Understanding how individual species contribute to nutrient transformations in a microbial community is critical to prediction of overall ecosystem function. We conducted microcosm experiments in which floating acid mine drainage (AMD) microbial biofilms were submerged - recapitulating the final stage in a natural biofilm life cycle. Biofilms were amended with either (15)NH4(+) or deuterium oxide ((2)H2O) and proteomic stable isotope probing (SIP) was used to track the extent to which different members of the community used these molecules in protein synthesis across anaerobic iron-reducing, aerobic iron-reducing and aerobic iron-oxidizing environments. Sulfobacillus spp. synthesized (15)N-enriched protein almost exclusively under iron-reducing conditions whereas the Leptospirillum spp. synthesized (15)N-enriched protein in all conditions. There were relatively few (15)N-enriched archaeal proteins, and all showed low atom% enrichment, consistent with Archaea synthesizing protein using the predominantly (14)N biomass derived from recycled biomolecules. In parallel experiments using (2)H2O, extensive archaeal protein synthesis was detected in all conditions. In contrast, the bacterial species showed little protein synthesis using (2)H2O. The nearly exclusive ability of Archaea to synthesize proteins using (2)H2O may be due to archaeal heterotrophy, whereby Archaea offset deleterious effects of (2)H by accessing (1)H generated by respiration of organic compounds. © 2014 Society for Applied Microbiology and John Wiley & Sons Ltd.

  2. Stable nitrogen and carbon isotope ratios indicate traditional and market food intake in an indigenous circumpolar population.

    PubMed

    Nash, Sarah H; Bersamin, Andrea; Kristal, Alan R; Hopkins, Scarlett E; Church, Rebecca S; Pasker, Renee L; Luick, Bret R; Mohatt, Gerald V; Boyer, Bert B; O'Brien, Diane M

    2012-01-01

    The transition of a society from traditional to market-based diets (termed the nutrition transition) has been associated with profound changes in culture and health. We are developing biomarkers to track the nutrition transition in the Yup'ik Eskimo population of Southwest Alaska based on naturally occurring variations in the relative abundances of carbon and nitrogen stable isotopes (δ(15)N and δ(13)C values). Here, we provide three pieces of evidence toward the validation of these biomarkers. First, we analyzed the δ(15)N and δ(13)C values of a comprehensive sample of Yup'ik foods. We found that δ(15)N values were elevated in fish and marine mammals and that δ(13)C values were elevated in market foods containing corn or sugar cane carbon. Second, we evaluated the associations between RBC δ(15)N and δ(13)C values and self-reported measures of traditional and market food intake (n = 230). RBC δ(15)N values were correlated with intake of fish and marine mammals (r = 0.52; P < 0.0001). RBC δ(13)C values were correlated with intake of market foods made from corn and sugar cane (r = 0.46; P < 0.0001) and total market food intake (r = 0.46; P < 0.0001). Finally, we assessed whether stable isotope ratios captured population-level patterns of traditional and market intake (n = 1003). Isotopic biomarkers of traditional and market intake were associated with age, community location, sex, and cultural identity. Self-report methods showed variations by age and cultural identity only. Thus, stable isotopes show potential as biomarkers for monitoring dietary change in indigenous circumpolar populations.

  3. Stable Nitrogen and Carbon Isotope Ratios Indicate Traditional and Market Food Intake in an Indigenous Circumpolar Population123

    PubMed Central

    Nash, Sarah H.; Bersamin, Andrea; Kristal, Alan R.; Hopkins, Scarlett E.; Church, Rebecca S.; Pasker, Renee L.; Luick, Bret R.; Mohatt, Gerald V.; Boyer, Bert B.; O’Brien, Diane M.

    2012-01-01

    The transition of a society from traditional to market-based diets (termed the nutrition transition) has been associated with profound changes in culture and health. We are developing biomarkers to track the nutrition transition in the Yup’ik Eskimo population of Southwest Alaska based on naturally occurring variations in the relative abundances of carbon and nitrogen stable isotopes (δ15N and δ13C values). Here, we provide three pieces of evidence toward the validation of these biomarkers. First, we analyzed the δ15N and δ13C values of a comprehensive sample of Yup’ik foods. We found that δ15N values were elevated in fish and marine mammals and that δ13C values were elevated in market foods containing corn or sugar cane carbon. Second, we evaluated the associations between RBC δ15N and δ13C values and self-reported measures of traditional and market food intake (n = 230). RBC δ15N values were correlated with intake of fish and marine mammals (r = 0.52; P < 0.0001). RBC δ13C values were correlated with intake of market foods made from corn and sugar cane (r = 0.46; P < 0.0001) and total market food intake (r = 0.46; P < 0.0001). Finally, we assessed whether stable isotope ratios captured population-level patterns of traditional and market intake (n = 1003). Isotopic biomarkers of traditional and market intake were associated with age, community location, sex, and cultural identity. Self-report methods showed variations by age and cultural identity only. Thus, stable isotopes show potential as biomarkers for monitoring dietary change in indigenous circumpolar populations. PMID:22157543

  4. Stable isotopic biogeochemistry of carbon and nitrogen in a perennially ice-covered Antarctic lake

    NASA Technical Reports Server (NTRS)

    Wharton, R. A. Jr; Lyons, W. B.; Des Marais, D. J.; Wharton RA, J. r. (Principal Investigator)

    1993-01-01

    remineralized as it falls through the water column. At nearby Lake Fryxell, the substantial (relative to Lake Hoare) glacial meltstream input overprints Fryxell's shallow-water biological delta 13C signal with delta 13C-depleted DIC. In contrast, Lake Hoare is not significantly affected by surface-water input and mixing, and therefore the delta 13C patterns observed arise primarily from biological dynamics within the lake. Organic matter in Lake Hoare is depleted in 15N, which we suggest is partially the result of the addition of relatively light inorganic nitrogen into the lake system from terrestrial sources.

  5. Use of Multiple Stable Isotopes to Quantify Nitrogen Deposition in Arid-Urban Ecosystems

    NASA Astrophysics Data System (ADS)

    Riha, K. M.; Michalski, G. M.; Hale, R. L.; Earl, S.; Turnbull, L.; Grimm, N. B.

    2011-12-01

    Atmospheric nitrogen (N) input to soils and surfaces in arid environments is of growing concern due to increased N emissions and N use associated with urbanization. Atmospheric N that falls as wet (rain or snow) or dry (dust or aerosols) deposition can lead to eutrophication, soil acidification, and groundwater contamination through leaching of excess nitrate. Other nitrate sources include anthropogenic fertilizer from agriculture practices or lawn application, septic systems, and animal waste. Urbanization increases imperviousness and alters natural flowpaths through construction of stormwater infrastructure, which alters hydrological connectivity. Following a rain pulse, nitrate deposited on impervious surfaces during dry periods may be mobilized and, depending on the type of stormwater infrastructure, has the potential to reach aquifers. In this study, we investigate the sources of nitrate found in urban stormwater by undertaking multiple-isotope analysis (δ15N, δ18O and Δ17O) on water samples collected from several sub-catchments within the Indian Bend Wash catchment in Scottsdale, Arizona, that represent different types of stormwater infrastructure, including pipes, engineered washes, retention basins and mixed infrastructure at larger spatial scales. We use δ15N of nitrate to distinguish among nitrate sources; pairing δ15N and δ18O provides more precise separation due to distinct signatures (e.g., fertilizer is unique from septic sources). Because atmospheric nitrate is anomalously enriched in 17O (denoted Δ17O) and nitrate produced from nitrification, denitrification and assimilation have a Δ17O = 0, we are able to use the Δ17O measurement to determine the proportion of nitrate in runoff that is derived from atmospheric sources. Multiple isotopic analyses were performed using the denitrifier method on runoff samples collected during summer (monsoonal) and winter storms that occurred between 2010 and 2011. Typical ranges of atmospheric nitrate inputs

  6. Stable carbon and nitrogen isotopes and amino acids in Holocene sediments of Lake Lonar, central India

    NASA Astrophysics Data System (ADS)

    Menzel, Philip; Gaye, Birgit; Wiesner, Martin; Basavaiah, Nathani; Prasad, Sushma; Stebich, Martina; Anoop, Ambili; Riedel, Nils

    2013-04-01

    Investigations on surface sediments and a sediment core from Lake Lonar in central India were carried out within the framework of the HIMPAC (Himalaya: Modern and Past Climate) programme. The aim was to understand recent productivity, sedimentation, and degradation processes and to reconstruct variations in Holocene lake conditions on the basis of biogeochemical analysis on a 10 m long sediment core retrieved from the centre of Lake Lonar. Located in India's core monsoon zone, Lake Lonar offers valuable information about the climate development of the whole region. The lake is situated at the floor of a meteorite impact structure on the Deccan plateau basalt. The modern lake is characterised by brackish water, high alkalinity, severe eutrophication, and bottom water anoxia. The lake is about 6 m deep and fed by rainfall during the SW monsoon season and three perennial streams. Since no out-flowing stream is present and no seepage loss occurs, the lake level is highly sensitive to the balance of precipitation and evaporation. Here we present C/N, carbon and nitrogen isotope, and amino acid data of bulk organic matter from modern lake and Holocene core sediments. Modern conditions are mainly related to human activity which started to have persistent influence on the biological and chemical lake properties at ~1200 cal a BP. The distribution of δ13C in the modern sediments is driven by the ratio between terrestrial and aquatic organic matter, while δ15N seems to be influenced by redox conditions at the sediment-water-interface with elevated values at shallow oxic stations. Differences in the amino acid assemblages of oxic and anoxic surface sediment samples were used to calculate an Ox/Anox ratio indicating the redox conditions during organic matter degradation. The onset of the monsoon reconstructed from the sediment core occurred at ca. 11450 cal a BP. The early Holocene core sediments are characterised by low sedimentation rate, low aquatic productivity, and

  7. [Element Sulfur Autotrophic Denitrification Combined Anaerobic Ammonia Oxidation].

    PubMed

    Zhou, Jian; Huang, Yong; Liu, Xin; Yuan, Yi; Li Xiang; Wangyan, De-qing; Ding, Liang; Shao, Jing-wei; Zhao, Rong

    2016-03-15

    A novel element sulfur autotrophic denitrification combined anaerobic ammonia oxidation process, reacted in CSTR, was used to investigate the sulfate production and alkalinity consumption during the whole process. The element sulfur dosage was 50 g · L⁻¹. The inoculation volume of ANAMMOX granular sludge was 100 g · L⁻¹. The agitation rate and environment reaction temperature of the CSTR were set to 120 r · min⁻¹ and 35°C ± 0.5°C, respectively. The pH of influent was maintained in range of 8. 0-8. 4. During the start-up stage of sulfur based autotrophic denitrification, the nitrogen removal loading rate could reach 0.56-0.71 kg · (m³ · d) ⁻¹ in the condition of 5.3 h hydrogen retention time and 200 mg · L⁻¹ nitrate nitrogen. After the addition of 60 mg · L⁻¹ ammonia nitrogen, Δn(SO₄²⁻):Δn(NO₃⁻) decreased from 1.21 ± 0.06 to 1.01 ± 0.10, Δ(IC): Δ(NO₃⁻-N) decreased from 0.72 ± 0.1 to 0.51 ± 0.11, and the effluent pH increased from 6.5 to 7.2. During the combined stage, the ammonia concentration of effluent was 10.1-19.2 mg · L⁻¹, and the nitrate-nitrogen removal loading rate could be maintained in range of 0.66-0.88 kg · (m³ · d)⁻¹. The Δn (NH₄⁺): Δn (NO₃⁻) ratio reached 0.43, and the NO₃⁻ removal rate was increased by 60% in the simultaneous ammonia and nitrate removal reaction under the condition of G(T) = 22-64 s⁻¹ and pH = 8.08, while improper conditions reduced the efficiency of simultaneous reaction.

  8. Nitrogen

    USGS Publications Warehouse

    Kramer, D.A.

    2006-01-01

    In 2005, ammonia was produced by 15 companies at 26 plants in 16 states in the United States. Of the total ammonia production capacity, 55% was centered in Louisiana, Oklahoma and Texas because of their large reserves of natural gas. US producers operated at 66% of their rated capacity. In descending order, Koch Nitrogen, Terra Industries, CF Industries, Agrium and PCS Nitrogen accounted for 81% of the US ammonia production capacity.

  9. Preservation Methods Alter Carbon and Nitrogen Stable Isotope Values in Crickets (Orthoptera: Grylloidea)

    PubMed Central

    Jesus, Fabiene Maria; Pereira, Marcelo Ribeiro; Rosa, Cassiano Sousa; Moreira, Marcelo Zacharias; Sperber, Carlos Frankl

    2015-01-01

    Stable isotope analysis (SIA) is an important tool for investigation of animal dietary habits for determination of feeding niche. Ideally, fresh samples should be used for isotopic analysis, but logistics frequently demands preservation of organisms for analysis at a later time. The goal of this study was to establish the best methodology for preserving forest litter-dwelling crickets for later SIA analysis without altering results. We collected two cricket species, Phoremia sp. and Mellopsis doucasae, from which we prepared 70 samples per species, divided among seven treatments: (i) freshly processed (control); preserved in fuel ethanol for (ii) 15 and (iii) 60 days; preserved in commercial ethanol for (iv) 15 and (v) 60 days; fresh material frozen for (vi) 15 and (vii) 60 days. After oven drying, samples were analyzed for δ15N, δ13C values, N(%), C(%) and C/N atomic values using continuous flow isotope ratio mass spectrometry. All preservation methods tested, significantly impacted δ13C and δ15N and C/N atomic values. Chemical preservatives caused δ13C enrichment as great as 1.5‰, and δ15N enrichment as great as 0.9‰; the one exception was M. doucasae stored in ethanol for 15 days, which had δ15N depletion up to 1.8‰. Freezing depleted δ13C and δ15N by up to 0.7 and 2.2‰, respectively. C/N atomic values decreased when stored in ethanol, and increased when frozen for 60 days for both cricket species. Our results indicate that all preservation methods tested in this study altered at least one of the tested isotope values when compared to fresh material (controls). We conclude that only freshly processed material provides adequate SIA results for litter-dwelling crickets. PMID:26390400

  10. Preservation Methods Alter Carbon and Nitrogen Stable Isotope Values in Crickets (Orthoptera: Grylloidea).

    PubMed

    Jesus, Fabiene Maria; Pereira, Marcelo Ribeiro; Rosa, Cassiano Sousa; Moreira, Marcelo Zacharias; Sperber, Carlos Frankl

    2015-01-01

    Stable isotope analysis (SIA) is an important tool for investigation of animal dietary habits for determination of feeding niche. Ideally, fresh samples should be used for isotopic analysis, but logistics frequently demands preservation of organisms for analysis at a later time. The goal of this study was to establish the best methodology for preserving forest litter-dwelling crickets for later SIA analysis without altering results. We collected two cricket species, Phoremia sp. and Mellopsis doucasae, from which we prepared 70 samples per species, divided among seven treatments: (i) freshly processed (control); preserved in fuel ethanol for (ii) 15 and (iii) 60 days; preserved in commercial ethanol for (iv) 15 and (v) 60 days; fresh material frozen for (vi) 15 and (vii) 60 days. After oven drying, samples were analyzed for δ15N, δ13C values, N(%), C(%) and C/N atomic values using continuous flow isotope ratio mass spectrometry. All preservation methods tested, significantly impacted δ13C and δ15N and C/N atomic values. Chemical preservatives caused δ13C enrichment as great as 1.5‰, and δ15N enrichment as great as 0.9‰; the one exception was M. doucasae stored in ethanol for 15 days, which had δ15N depletion up to 1.8‰. Freezing depleted δ13C and δ15N by up to 0.7 and 2.2‰, respectively. C/N atomic values decreased when stored in ethanol, and increased when frozen for 60 days for both cricket species. Our results indicate that all preservation methods tested in this study altered at least one of the tested isotope values when compared to fresh material (controls). We conclude that only freshly processed material provides adequate SIA results for litter-dwelling crickets.

  11. Carbon isotope effects associated with autotrophic acetogenesis

    USGS Publications Warehouse

    Gelwicks, J.T.; Risatti, J.B.; Hayes, J.M.

    1989-01-01

    The carbon kinetic isotope effects associated with synthesis of acetate from CO2 and H2 during autotrophic growth of Acetobacterium woodii at 30??C have been measured by isotopic analyses of CO2, methyl-carbon, and total acetate. Closed systems allowing construction of complete mass balances at varying stages of growth were utilized, and the effects of the partitioning of carbon between CO2 and HCO3- were taken into account. For the overall reaction, total carbonate ??? total acetate, isotope effects measured in replicate experiments ranged from -59.0 ?? 0.9% to - 57.2 ?? 2.3z%. Taking into account all measurements, the weighted mean and standard deviation are -58.6 ?? 0.7%. There is no evidence for intramolecular ordering in the acetate. The carbon isotopic composition of sedimentary acetate, otherwise expected to be near that of sedimentary organic carbon, is likely to be depleted in environments in which autotrophic acetogenesis is occurring. ?? 1989.

  12. Impact of contamination and pre-treatment on stable carbon and nitrogen isotopic composition of charred plant remains.

    PubMed

    Vaiglova, Petra; Snoeck, Christophe; Nitsch, Erika; Bogaard, Amy; Lee-Thorp, Julia

    2014-12-15

    Stable isotope analysis of archaeological charred plants has become a useful tool for interpreting past agricultural practices and refining ancient dietary reconstruction. Charred material that lay buried in soil for millennia, however, is susceptible to various kinds of contamination, whose impact on the grain/seed isotopic composition is poorly understood. Pre-treatment protocols have been adapted in distinct forms from radiocarbon dating, but insufficient research has been carried out on evaluating their effectiveness and necessity for stable carbon and nitrogen isotope analysis. The effects of previously used pre-treatment protocols on the isotopic composition of archaeological and modern sets of samples were investigated. An archaeological sample was also artificially contaminated with carbonates, nitrates and humic acid and subjected to treatment aimed at removing the introduced contamination. The presence and removal of the contamination were investigated using Fourier transform infrared spectroscopy (FTIR) and δ(13)C and δ(15)N values. The results show a ca 1‰ decrease in the δ(15)N values of archaeological charred plant material caused by harsh acid treatments and ultra-sonication. This change is interpreted as being caused by mechanical distortion of the grains/seeds rather than by the removal of contamination. Furthermore, specific infrared peaks have been identified that can be used to detect the three types of contaminants studied. We argue that it is not necessary to try to remove humic acid contamination for stable isotope analysis. The advantages and disadvantages of crushing the grains/seeds before pre-treatment are discussed. We recommend the use of an acid-only procedure (0.5 M HCl for 30 min at 80 °C followed by three rinses in distilled water) for cleaning charred plant remains. This study fills an important gap in plant stable isotope research that will enable future researchers to evaluate potential sources of isotopic change and pre

  13. Impact of contamination and pre-treatment on stable carbon and nitrogen isotopic composition of charred plant remains

    PubMed Central

    Vaiglova, Petra; Snoeck, Christophe; Nitsch, Erika; Bogaard, Amy; Lee-Thorp, Julia

    2014-01-01

    Rationale Stable isotope analysis of archaeological charred plants has become a useful tool for interpreting past agricultural practices and refining ancient dietary reconstruction. Charred material that lay buried in soil for millennia, however, is susceptible to various kinds of contamination, whose impact on the grain/seed isotopic composition is poorly understood. Pre-treatment protocols have been adapted in distinct forms from radiocarbon dating, but insufficient research has been carried out on evaluating their effectiveness and necessity for stable carbon and nitrogen isotope analysis. Methods The effects of previously used pre-treatment protocols on the isotopic composition of archaeological and modern sets of samples were investigated. An archaeological sample was also artificially contaminated with carbonates, nitrates and humic acid and subjected to treatment aimed at removing the introduced contamination. The presence and removal of the contamination were investigated using Fourier transform infrared spectroscopy (FTIR) and δ13C and δ15N values. Results The results show a ca 1‰ decrease in the δ15N values of archaeological charred plant material caused by harsh acid treatments and ultra-sonication. This change is interpreted as being caused by mechanical distortion of the grains/seeds rather than by the removal of contamination. Furthermore, specific infrared peaks have been identified that can be used to detect the three types of contaminants studied. We argue that it is not necessary to try to remove humic acid contamination for stable isotope analysis. The advantages and disadvantages of crushing the grains/seeds before pre-treatment are discussed. Conclusions We recommend the use of an acid-only procedure (0.5 M HCl for 30 min at 80°C followed by three rinses in distilled water) for cleaning charred plant remains. This study fills an important gap in plant stable isotope research that will enable future researchers to evaluate potential

  14. Infant feeding practice in medieval Japan: stable carbon and nitrogen isotope analysis of human skeletons from Yuigahama-minami.

    PubMed

    Tsutaya, Takumi; Shimomi, Akina; Nagaoka, Tomohito; Sawada, Junmei; Hirata, Kazuaki; Yoneda, Minoru

    2015-02-01

    A longer breastfeeding duration provides various positive effects in subadult health because of abundant immunological factors and nutrients in human breast milk, and decreases the natural fertility of a population through lactational amenorrhea. In this study, we measured stable carbon and nitrogen isotope ratios in the bone collagen of three adults and 45 subadults from the Yuigahama-minami site (from 12th to 14th century) in Kamakura, the early medieval capital of Japan. Marine foods, C3 -based terrestrial foods, and freshwater fish are the primarily protein sources for adults. The changes in the nitrogen isotope ratios of subadults suggest that the relative dietary protein contribution from breast milk started to decrease from 1.1 years of age and ended at 3.8 years. The age at the end of weaning in the Yuigahama-minami population was greater than that in the typical non-industrial populations, a premodern population in the Edo period Japan, and medieval populations in the UK. Skeletons of townspeople from medieval Kamakura indicate severe nutritional stress (e.g., enamel hypoplasia and cribra orbitalia), yet this longer duration of breastfeeding did not compensate adverse effects for nutritional deficiency. The longer breastfeeding period may have been a consequence of complementary food shortage and bad health of subadults. Kamakura experienced urbanization and population increase in the early medieval period. The younger age-at-death distribution and high nutritional stresses in the Yuigahama-minami population and later weaning, which is closely associated with longer inter-birth interval for mothers, suggests that Kamakura developed and increased its population by immigration during urbanization. © 2015 Wiley Periodicals, Inc.

  15. Differential processing of anthropogenic carbon and nitrogen in benthic food webs of A Coruña (NW Spain) traced by stable isotopes

    NASA Astrophysics Data System (ADS)

    Bode, Antonio; Fernández, Consolación; Mompeán, Carmen; Parra, Santiago; Rozada, Fernando; Valencia-Vila, Joaquín; Viana, Inés G.

    2014-08-01

    In this study the effect of inputs of organic matter and anthropogenic nitrogen at small spatial scales were investigated in the benthos of the Ria of A Coruña (NW Spain) using stable carbon and nitrogen isotopes. This ria is characteristically enriched in nutrients provided either by marine processes (as coastal upwelling) or by urban and agricultural waste. Stable isotope composition in trophic guilds of infaunal benthos revealed spatial differences related to their nutrient inputs. The main difference was the presence of an additional chemoautotrophic food web at the site with a large accumulation of organic matter. The enrichment in heavy nitrogen isotopes observed in most compartments suggests the influence of sewage-derived nitrogen, despite large inputs of marine nitrogen. Macroalgae (Fucus vesiculosus) resulted significantly enriched at the site influenced by estuarine waters. In contrast, no differences were found in mussels (Mytilus galloprovincialis), thus suggesting a major dependence on marine nutrient sources for this species. However, the estimations of anthropogenic influence were largely dependent on assumptions required to model the different contributions of sources. The measurement of stable isotope signatures in various compartments revealed that, despite anthropogenic nutrients are readily incorporated into local food webs, a major influence of natural marine nutrient sources cannot be discarded.

  16. Competition between autotrophic and heterotrophic microbial plankton for inorganic nutrients induced by variability in estuarine biophysicochemical conditions

    NASA Astrophysics Data System (ADS)

    Williams, A.; Quigg, A.

    2016-02-01

    Competition for inorganic nutrients between autotrophic and heterotrophic fractions of microbial plankton (0.2-20μm) was investigated at two stations in a sub-tropical estuary, Galveston Bay, Texas. Competition potential between these groups is enhanced because individuals are similar in size, reducing variability among their nutrient uptake efficiencies. Further, in estuaries, allochthonous supplements to autochthonous carbon may satisfy heterotrophic requirements, allowing alternative factors to limit abundance. The relative abundance of autotrophs and heterotrophs stained with SYBR Green I and enumerated on a Beckman Coulter Gallios flow cytometer were evaluated monthly during a year-long study. Shifts in the relative in situ abundance were significantly related to temperature, dissolved inorganic nitrogen (DIN), phosphorous (Pi), and total organic carbon (TOC) concentrations revealing opposing gradients of limitation by different abiotic factors. In corresponding in vitro nutrient enrichment bioassays the relative contribution of autotrophic or heterotrophic microbial plankton to significant enrichment responses varied. Only during macro- (>20μm) phytoplankton blooms do autotrophic microbial plankton respond to nutrient enrichment. Contrastingly, the heterotrophic microbial plankton responded to nutrient enrichment primarily when temperature limitation was alleviated. Therefore, the potential for autotrophic and heterotrophic microbial plankton competition for limiting nutrients is highest when autotrophic microbial plankton are also competing with larger phytoplankton during bloom events. Based on this evidence, we hypothesize that the autotrophic microbial fraction has a competitive advantage over the heterotrophs for inorganic nutrients in Galveston Bay. The observed microbial competition during estuarine phytoplankton blooms may have important consequences on biogeochemical processes including carbon and nutrient cycling.

  17. Nitrogen

    USGS Publications Warehouse

    Apodaca, L.E.

    2012-01-01

    Ammonia was produced by 12 companies at 27 plants in 15 states in the United States during 2011. Sixty-one percent of total U.S. ammonia production capacity was centered in Louisiana, Oklahoma and Texas because of those states' large reserves of natural gas, the dominant domestic feedstock. In 2011, U.S. producers operated at about 84 percent of their rated capacity (excluding plants that were idle for the entire year). Four companies — CF Industries Holdings Inc.; Koch Nitrogen Co.; PCS Nitrogen Inc. and Agrium Inc., in descending order — accounted for 77 percent of the total U.S. ammonia production capacity.

  18. Stable nitrogen and carbon isotopes in sediments and biota from three tropical marine food webs: Application to chemical bioaccumulation assessment.

    PubMed

    Zhang, Hui; Teng, Yun; Doan, Tra Thi Thanh; Yat, Yun Wei; Chan, Sheot Harn; Kelly, Barry C

    2017-09-01

    Studies of trophodynamics and contaminant bioaccumulation in tropical marine ecosystems are limited. The present study employed stable isotope and trace contaminant analysis to assess sources of primary productivity, trophic interactions, and chemical bioaccumulation behavior in 2 mangrove food webs and 1 offshore coastal marine food web in Singapore. Samples of sediment, phytoplankton, mangrove leaves, clams, snails, crabs, worms, prawns, and fishes were analyzed for stable carbon and nitrogen isotope values, as well as concentrations of persistent organic pollutants. In the mangrove food webs, consumers exhibited similar δ(13) C values, probably because of the well-mixed nature of these systems. However, the 2 primary consumers (common nerite and rodong snail) exhibited distinct δ(13) C values (-21.6‰ vs -17.7‰), indicating different carbon sources. Fish from Singapore Strait exhibited similar δ(13) C values, indicating common carbon sources in this offshore marine food web. The highest trophic level was found in glass perchlet (trophic level = 3.3) and tilapia (trophic level = 3.4) in the 2 mangrove food webs and grunter (trophic level = 3.7) in the Singapore Strait food web. Concentrations of polychlorinated biphenyl (PCB 153) and p,p'-dichlorodiphenyldichloroethylene (p,p'-DDE) concentrations ranged from 0.9 to 84.6 ng/g lipid weight and from <0.2 to 267.4 ng/g lipid weight, respectively. The trophic magnification factors of PCB 153 and p,p'-DDE ranged between 1.63 and 4.62, indicating biomagnification in these tropical marine food webs. The findings provide important information that will aid future chemical bioaccumulation assessment initiatives. Environ Toxicol Chem 2017;36:2521-2532. © 2017 SETAC. © 2017 SETAC.

  19. Incorporation of carbon and nitrogen atoms into proteins measured by protein-based stable isotope probing (Protein-SIP).

    PubMed

    Jehmlich, Nico; Schmidt, Frank; Hartwich, Mathias; von Bergen, Martin; Richnow, Hans-Hermann; Vogt, Carsten

    2008-09-01

    The identification of metabolically active microbial key players is fundamental for understanding the structure and functions of contaminant-degrading communities. The metabolic activity can be analysed by feeding the microbial culture with stable-isotope-labelled substrates and subsequently tracing their incorporation into the biomass. In this paper we present a method which is able to detect the incorporation of stable isotopes from the substrate into the proteins of a benzene-metabolising microorganism. Pseudomonas putida strain ML2 was grown under aerobic conditions with the substrates (12)C-benzene, (13)C-benzene or (15)N-ammonium and (12)C-benzene. Proteins of these cultures were resolved by two-dimensional gel electrophoresis (2-DE) and corresponding protein spots were subjected to matrix-assisted laser ionization/desorption mass spectrometric (MALDI-MS) analysis. The proteins of the (12)C-sample were identified by peptide mass fingerprinting (PMF) as well as by tandem mass spectrometric (MS/MS) measurements. The (13)C- or (15)N-content of the peptides from the labelling experiments was determined by MALDI-MS/MS. The incorporation of heavy isotopes into the proteins from cultures grown on (13)C-benzene and (15)N-ammonium was determined based on the mass differences between labelled and non-labelled peptides as well as on the isotopic distribution of the y(1)-ion of arginine. The method we present here principally allows the unravelling of the carbon and nitrogen flow not only in pure cultures, but also in microbial communities consisting of many microbial species. Copyright (c) 2008 John Wiley & Sons, Ltd.

  20. Stable carbon, oxygen, and nitrogen, isotope analysis of plants from a South Asian tropical forest: Implications for primatology.

    PubMed

    Roberts, Patrick; Blumenthal, Scott A; Dittus, Wolfgang; Wedage, Oshan; Lee-Thorp, Julia A

    2017-03-27

    Stable isotope analysis of primate tissues in tropical forest contexts is an increasingly popular means of obtaining information about niche distinctions among sympatric species, including preferences in feeding height, forest canopy density, plant parts, and trophism. However, issues of equifinality mean that feeding height, canopy density, as well as the plant parts and plant species consumed, may produce similar or confounding effects. With a few exceptions, researchers have so far relied largely on general principles and/or limited plant data from the study area as references for deducing the predominant drivers of primate isotope variation. Here, we explore variation in the stable carbon (δ(13) C), nitrogen (δ(15) N), and oxygen (δ(18) O) isotope ratios of 288 plant samples identified as important to the three primate species from the Polonnaruwa Nature Sanctuary, Sri Lanka, relative to plant part, season, and canopy height. Our results show that plant part and height have the greatest effect on the δ(13) C and δ(18) O measurements of plants of immediate relevance to the primates, Macaca sinica, Semnopithecus priam thersites, and Trachypithecus vetulus, living in this monsoonal tropical forest. We find no influence of plant part, height or season on the δ(15) N of measured plants. While the plant part effect is particularly pronounced in δ(13) C between fruits and leaves, differential feeding height, and plant taxonomy influence plant δ(13) C and δ(18) O differences in addition to plant organ. Given that species composition in different regions and forest types will differ, the results urge caution in extrapolating general isotopic trends without substantial local baselines studies.

  1. Variation of hydrogen, carbon, nitrogen, and oxygen stable isotope ratios in an American diet: fast food meals.

    PubMed

    Chesson, Lesley A; Podlesak, David W; Thompson, Alexandra H; Cerling, Thure E; Ehleringer, James R

    2008-06-11

    The stable isotopes of hydrogen, carbon, nitrogen, and oxygen provide insights into a heterotrophic organism's diet and geographic origin. Although the contribution of food delta (2)H and delta (18)O to the final tissue signal will not vary for constrained diets, it will for animals eating varied diets, that is, humans. This study surveyed the isotopic range in one portion of the American diet, fast food meals. Hamburger patties, buns, and French fries from national chain restaurants across the United States and from local restaurants (Salt Lake City, UT, and Charleston, SC) were analyzed for delta (2)H, delta (13)C, delta (15)N (patties only) and delta (18)O values. Patties and buns from local Utah restaurants were more depleted for delta (2)H, delta (13)C, and delta (18)O values than samples from other restaurants. There were no significant differences in delta values among French fries. All three components of the fast food meal displayed significant linear delta (2)H versus delta (18)O relationships (delta (2)H = 7.8delta (18)O - 237 per thousand, delta (2)H = 5.9delta (18)O - 258 per thousand, and delta (2)H = 3.3delta (18)O - 231 per thousand for patties, buns, and fries, respectively). The findings show that significant predictable variation exists in the stable isotopic composition of fast food meals. It is proposed that the variation in delta (13)C values of hamburger (beef) patties is indicative of differences in cattle-rearing practices, whereas delta (2)H and delta (18)O values are evidence of geographic variation in food sources. Although the patterns support the concept of a "continental" supermarket diet, there appears to be a strong regional component within the diet.

  2. Alteration of the carbon and nitrogen stable isotope composition of beef by substitution of grass silage with maize silage.

    PubMed

    Bahar, Bojlul; Monahan, Frank J; Moloney, Aidan P; O'Kiely, Padraig; Scrimgeour, Charlie M; Schmidt, Olaf

    2005-01-01

    This study investigated the effect of substituting grass silage (C3 photosynthetic plant product) with maize silage (C4 photosynthetic plant product) on the natural abundance carbon (delta13C) and nitrogen (delta15N) stable isotope composition of bovine muscle tissue. Forty-five continental crossbred heifers were assigned to one of three diets consisting of 3 kg of a barley-based concentrate plus grass silage, maize silage or an equal mixture (dry matter basis) of grass silage and maize silage, fed ad libitum, for 167 days. Substitution resulted in less negative delta13C values (P<0.001) in lipid-free muscle and in lipid, and also a lower delta15N (P<0.001) in lipid-free muscle. Feeding of maize silage was clearly reflected in the delta13C of muscle, with each 10% difference in the dietary C4 carbon intake resulting in a 0.9 to 1.0 per thousand shift of delta13C in lipid-free muscle and a 1.0 to 1.2 per thousand in lipid. Minimum detectable mean differences (95% confidence, power 0.80, n=15) in this experiment were about 0.5 per thousand and 1.0 per thousand for delta13C of lipid-free muscle and lipid, respectively, and about 0.5 per thousand for delta15N of lipid-free muscle. The power analysis presented here is useful for estimating minimum isotopic differences that can be detected between any two groups of beef samples with a given number of replicates. It is concluded that carbon stable isotope ratio analysis of meat can be used to quantify C3/C4 dietary constituents in beef production. Copyright (c) 2005 John Wiley & Sons, Ltd.

  3. Nitrogen

    USGS Publications Warehouse

    Kramer, D.A.

    2004-01-01

    Ammonia is the principal source of fixed nitrogen. It was produced by 17 companies at 34 plants in the United States during 2003. Fifty-three percent of U.S. ammonia production capacity was centered in Louisiana, Oklahoma and Texas because of their large reserves of natural gas, the dominant domestic feedstock.

  4. Wastewater nitrogen and trace metal uptake by biota on a high-energy rocky shore detected using stable isotopes.

    PubMed

    Oakes, Joanne M; Eyre, Bradley D

    2015-11-15

    On high-energy rocky shores receiving treated wastewater, impacts are difficult to distinguish against a highly variable background and are localised due to rapid dilution. We demonstrate that nitrogen stable isotope values (δ(15)N) of rocky shore biota are highly sensitive to wastewater inputs. For macroalgae (Ulva lactuca and Endarachne binghamiae), grazing snails (Bembicium nanum and Nerita atramentosa), and predatory snails (Morula marginalba), δ(15)N was enriched near a wastewater outfall and declined with distance, returning to background levels within 290m. Any of these species therefore indicates the extent of influence of wastewater, allowing identification of an appropriate scale for studies of ecosystem impacts. For M. marginalba, significant regressions between δ(15)N and tissue copper, manganese, and zinc concentrations indicate a possible wastewater source for these metals. This suggests that δ(15)N is a proxy for exposure to wastewater contaminants, and may help to attribute variations in rocky shore communities to wastewater impacts. Copyright © 2015 Elsevier Ltd. All rights reserved.

  5. Sustainable energy recovery in wastewater treatment by microbial fuel cells: stable power generation with nitrogen-doped graphene cathode.

    PubMed

    Liu, Yuan; Liu, Hong; Wang, Chuan; Hou, Shuang-Xia; Yang, Nuan

    2013-12-03

    Microbial fuel cells (MFCs) recover energy sustainably in wastewater treatment. Performance of non-noble cathode catalysts with low cost in neutral medium is vital for stable power generation. Nitrogen-doped graphene (NG) as cathode catalyst was observed to exhibit high and durable activity at buffered pH 7.0 during electrochemical measurements and in MFCs with respect to Pt/C counterpart. Electrochemical measurements showed that the oxygen reduction reaction (ORR) on NG possessed sustained activity close to the state-of-art Pt/C in terms of onset potential and electron transfer number. NG-MFCs displayed maximum voltage output of 650 mV and maximum power density of 776 ± 12 mW m(-2), larger than 610 mV and 750 ± 19 mW m(-2) of Pt/C-MFCs, respectively. Furthermore, long-time test lasted over 90 days, during which the maximum power density of NG-MFCs declined by 7.6%, with stability comparable to Pt/C-MFCs. Structure characterization of NG implied that the relatively concentrated acidic oxygen-containing groups improved such long-time stability by repelling the protons due to the same electrostatic force, and thus the C-N active centers for ORR were left undestroyed. These findings demonstrated the competitive advantage of NG to advance the application of MFCs for recovering biomass energy in treatment of wastewater with neutral pH.

  6. Tracing nitrogenous disinfection byproducts after medium pressure UV water treatment by stable isotope labeling and high resolution mass spectrometry.

    PubMed

    Kolkman, Annemieke; Martijn, Bram J; Vughs, Dennis; Baken, Kirsten A; van Wezel, Annemarie P

    2015-04-07

    Advanced oxidation processes are important barriers for organic micropollutants (e.g., pharmaceuticals, pesticides) in (drinking) water treatment. Studies indicate that medium pressure (MP) UV/H2O2 treatment leads to a positive response in Ames mutagenicity tests, which is then removed after granulated activated carbon (GAC) filtration. The formed potentially mutagenic substances were hitherto not identified and may result from the reaction of photolysis products of nitrate with (photolysis products of) natural organic material (NOM). In this study we present an innovative approach to trace the formation of disinfection byproducts (DBPs) of MP UV water treatment, based on stable isotope labeled nitrate combined with high resolution mass spectrometry. It was shown that after MP UV treatment of artificial water containing NOM and nitrate, multiple nitrogen containing substances were formed. In total 84 N-DBPs were detected at individual concentrations between 1 to 135 ng/L bentazon-d6 equivalents, with a summed concentration of 1.2 μg/L bentazon-d6 equivalents. The chemical structures of three byproducts were confirmed. Screening for the 84 N-DBPs in water samples from a full-scale drinking water treatment plant based on MP UV/H2O2 treatment showed that 22 of the N-DBPs found in artificial water were also detected in real water samples.

  7. Nitrogen stable isotope ratios of anthropgenic organic matter in the coastal environment of Kosirina Bay (Murter Island, Croatia)

    NASA Astrophysics Data System (ADS)

    Dolenec, T.; Lambaša, Ž.; Lojen, S.; Rogan, N.; Kniewald, G.; Dolenec, M.

    2009-04-01

    In this study stable nitrogen isotopes ratios of particulate matter POM, zooplankton and selected biota such as Anemonia sulcata and Mytilus galloprovincialis were used to assessed the impact of anthropogenically derived organic matter from the untreated domestic sewage, municipal and industrial effluents on the coastal ecosystem of the Kosirina Bay (Murter Island). The differences in δ15N values observed in POM and organisms collected in Kosirina Bay as compared to POM and biota sampled at unaffected sites from the southern part of the Kornati Island and highly impacted Pirovac Bay revealed only a very minor effects of anthropogenic inputs of nutrients and organic matter which most probably derived from a sewage outfall south of the Tužbina Island. However, to get a better insight into the qualitative or quantitative shifts in the structure of aquatic food web caused by pollutants, more extended research on benthic population is needed, as well as a detailed investigation of seasonal variations of abundance and isotopic composition of POM and zooplankton as their presumed food source.

  8. Nitrogen-doped carbon onions encapsulating metal alloys as efficient and stable catalysts for dye-sensitized solar cells

    NASA Astrophysics Data System (ADS)

    Zhu, Chongyang; Xu, Feng; Chen, Jing; Min, Huihua; Dong, Hui; Tong, Ling; Qasim, Khan; Li, Shengli; Sun, Litao

    2016-01-01

    Designing a new class of non-noble metal catalysts with triiodide reduction activity and stability comparable to those of conventional Pt is extremely significant for the application of dye-sensitized solar cells (DSSCs). Here, we demonstrate newly designed counter electrode (CE) materials of onion-like nitrogen-doped carbon encapsulating metal alloys (ONC@MAs) such as FeNi3 (ONC@FeNi3) or FeCo (ONC@FeCo), by a facile and scalable pyrolysis method. The resulting composite catalysts show superior catalytic activities towards the triiodide reduction and exhibit low charge transfer resistance between the electrode surfaces and electrolytes. As a result, the DSSCs based on ONC@FeCo and ONC@FeNi3 achieve outstanding power conversion efficiencies (PCEs) of 8.26% and 8.87%, respectively, which can rival the 8.28% of Pt-based DSSC. Moreover, the excellent electrochemical stabilities for both the two catalysts also have been corroborated by electrochemical impendence spectra and cyclic voltammetry (CV). Noticeably, TEM investigation further reveals that the N-doped graphitic carbon onions exhibit the high structural stability in iodine-containing medium even subject to hundreds of CV scanning. These results make ONC@MAs the promising candidates to supersede costly Pt as efficient and stable CEs for DSSCs.

  9. Mercury concentrations in fish from forest harvesting and fire-impacted Canadian Boreal lakes compared using stable isotopes of nitrogen.

    PubMed

    Garcia, Edenise; Carignan, Richard

    2005-03-01

    Total mercury (Hg) concentration was determined in several piscivorous and nonpiscivorous species of fish from 38 drainage lakes with clear-cut, burnt, or undisturbed catchments located in the Canadian Boreal Shield. Mercury concentrations increased with increasing fish trophic position as estimated using stable isotopes of nitrogen (N; r2 = 0.52, 0.49, and 0.30 for cut, reference, and burnt lakes, respectively; p < 0.01). Mercury biomagnification per thousand delta15N varied from 22 to 29% in the three groups of lakes. Mercury availability to organisms at the base of the food chain in lakes with cut catchments was higher than that in reference lakes. In cut lakes, Hg concentrations in fish were significantly related to ratio of the clear-cut area to lake area (or lake volume; r = +0.82 and +0.74, respectively, p < 0.01). Both impact ratios were, in turn, significantly correlated with dissolved organic carbon. These findings suggest that differential loading of organic matter-bound Hg to lakes can affect Hg cycling. In addition, Hg concentrations exceeded the advisory limit for human consumption (0.5 microg/g wet wt) from the World Health Organization in all top predatory species (northern pike, walleye, and burbot) found in cut and in two partially burnt lakes. Thus, high Hg concentrations in fish from forest-harvested and partially burnt lakes may reflect increased exposure to Hg relative to that in lakes not having these watershed disturbances.

  10. Nitrogen

    USGS Publications Warehouse

    Kramer, D.A.

    2007-01-01

    Ammonia was produced by 15 companies at 25 plants in 16 states in the United States during 2006. Fifty-seven percent of U.S. ammonia production capacity was centered in Louisiana, Oklahoma and Texas because of their large reserves of natural gas, the dominant domestic feedstock. In 2006, U.S. producers operated at about 72 percent of their rated capacity (excluding plants that were idle for the entire year). Five companies, Koch Nitrogen, Terra Industries, CF Industries, PCS Nitro-gen, and Agrium, in descending order, accounted for 79 percent U.S. ammonia production capacity. The United States was the world's fourth-ranked ammonia producer and consumer following China, India and Russia. Urea, ammonium nitrate, ammonium phosphates, nitric acid and ammonium sulfate were the major derivatives of ammonia in the United States, in descending order of importance.

  11. Nitrogen

    USGS Publications Warehouse

    Apodaca, L.E.

    2010-01-01

    Ammonia was produced by 13 companies at 23 plants in 16 states during 2009. Sixty percent of all U.S. ammonia production capacity was centered in Louisiana. Oklahoma and Texas because of those states' large reserves of natural gas, the dominant domestic feedstock. In 2009, U.S. producers operated at about 83 percent of their rated capacity (excluding plants that were idle for the entire year). Five companies — Koch Nitrogen Co.; Terra Industries Inc.; CF Industries Inc.; PCS Nitrogen Inc. and Agrium Inc., in descending order — accounted for 80 percent of the total U.S. ammonia production capacity. U.S. production was estimated to be 7.7 Mt (8.5 million st) of nitrogen (N) content in 2009 compared with 7.85 Mt (8.65 million st) of N content in 2008. Apparent consumption was estimated to have decreased to 12.1 Mt (13.3 million st) of N, a 10-percent decrease from 2008. The United States was the world's fourth-ranked ammonia producer and consumer following China, India and Russia. Urea, ammonium nitrate, ammonium phosphates, nitric acid and ammonium sulfate were the major derivatives of ammonia in the United States, in descending order of importance.

  12. Autotrophic growth of bacterial and archaeal ammonia oxidizers in freshwater sediment microcosms incubated at different temperatures.

    PubMed

    Wu, Yucheng; Ke, Xiubin; Hernández, Marcela; Wang, Baozhan; Dumont, Marc G; Jia, Zhongjun; Conrad, Ralf

    2013-05-01

    Both bacteria and archaea potentially contribute to ammonia oxidation, but their roles in freshwater sediments are still poorly understood. Seasonal differences in the relative activities of these groups might exist, since cultivated archaeal ammonia oxidizers have higher temperature optima than their bacterial counterparts. In this study, sediment collected from eutrophic freshwater Lake Taihu (China) was incubated at different temperatures (4°C, 15°C, 25°C, and 37°C) for up to 8 weeks. We examined the active bacterial and archaeal ammonia oxidizers in these sediment microcosms by using combined stable isotope probing (SIP) and molecular community analysis. The results showed that accumulation of nitrate in microcosms correlated negatively with temperature, although ammonium depletion was the same, which might have been related to enhanced activity of other nitrogen transformation processes. Incubation at different temperatures significantly changed the microbial community composition, as revealed by 454 pyrosequencing targeting bacterial 16S rRNA genes. After 8 weeks of incubation, [(13)C]bicarbonate labeling of bacterial amoA genes, which encode the ammonia monooxygenase subunit A, and an observed increase in copy numbers indicated the activity of ammonia-oxidizing bacteria in all microcosms. Nitrosomonas sp. strain Is79A3 and Nitrosomonas communis lineages dominated the heavy fraction of CsCl gradients at low and high temperatures, respectively, indicating a niche differentiation of active bacterial ammonia oxidizers along the temperature gradient. The (13)C labeling of ammonia-oxidizing archaea in microcosms incubated at 4 to 25°C was minor. In contrast, significant (13)C labeling of Nitrososphaera-like archaea and changes in the abundance and composition of archaeal amoA genes were observed at 37°C, implicating autotrophic growth of ammonia-oxidizing archaea under warmer conditions.

  13. Autotrophic Growth of Bacterial and Archaeal Ammonia Oxidizers in Freshwater Sediment Microcosms Incubated at Different Temperatures

    PubMed Central

    Wu, Yucheng; Ke, Xiubin; Hernández, Marcela; Wang, Baozhan; Dumont, Marc G.; Jia, Zhongjun

    2013-01-01

    Both bacteria and archaea potentially contribute to ammonia oxidation, but their roles in freshwater sediments are still poorly understood. Seasonal differences in the relative activities of these groups might exist, since cultivated archaeal ammonia oxidizers have higher temperature optima than their bacterial counterparts. In this study, sediment collected from eutrophic freshwater Lake Taihu (China) was incubated at different temperatures (4°C, 15°C, 25°C, and 37°C) for up to 8 weeks. We examined the active bacterial and archaeal ammonia oxidizers in these sediment microcosms by using combined stable isotope probing (SIP) and molecular community analysis. The results showed that accumulation of nitrate in microcosms correlated negatively with temperature, although ammonium depletion was the same, which might have been related to enhanced activity of other nitrogen transformation processes. Incubation at different temperatures significantly changed the microbial community composition, as revealed by 454 pyrosequencing targeting bacterial 16S rRNA genes. After 8 weeks of incubation, [13C]bicarbonate labeling of bacterial amoA genes, which encode the ammonia monooxygenase subunit A, and an observed increase in copy numbers indicated the activity of ammonia-oxidizing bacteria in all microcosms. Nitrosomonas sp. strain Is79A3 and Nitrosomonas communis lineages dominated the heavy fraction of CsCl gradients at low and high temperatures, respectively, indicating a niche differentiation of active bacterial ammonia oxidizers along the temperature gradient. The 13C labeling of ammonia-oxidizing archaea in microcosms incubated at 4 to 25°C was minor. In contrast, significant 13C labeling of Nitrososphaera-like archaea and changes in the abundance and composition of archaeal amoA genes were observed at 37°C, implicating autotrophic growth of ammonia-oxidizing archaea under warmer conditions. PMID:23455342

  14. Effect of baking and fermentation on the stable carbon and nitrogen isotope ratios of grain-based food.

    PubMed

    Bostic, Joshua N; Palafox, Sherilyn J; Rottmueller, Marina E; Jahren, A Hope

    2015-05-30

    Isotope ratio mass spectrometry (IRMS) is used extensively to reconstruct general attributes of prehistoric and modern diets in both humans and animals. In order to apply these methods to the accurate determination of specific intakes of foods/nutrients of interest, the isotopic signature of individually consumed foods must be constrained. For example, 86% of the calories consumed in the USA are derived from processed and prepared foods, but the relationship between the stable isotope composition of raw ingredients and the resulting products has not been characterized. To examine the effect of common cooking techniques on the stable isotope composition of grain-based food items, we prepared yeast buns and sugar cookies from standardized recipes and measured bulk δ(13) C and δ(15) N values of samples collected throughout a 75 min fermentation process (buns) and before and after baking at 190°C (buns and cookies). Simple isotope mixing models were used to determine if the isotopic signatures of 13 multi-ingredient foods could be estimated from the isotopic signatures of their constituent raw ingredients. No variations in δ(13) C or δ(15) N values were detected between pre- and post-baked yeast buns (pre: -24.78‰/2.61‰, post: -24.75‰/2.74‰), beet-sugar cookies (pre: -24.48‰/3.84‰, post: -24.47‰/3.57‰), and cane-sugar cookies (pre: -19.07‰/2.97‰, post: -19.02‰/3.21‰), or throughout a 75 min fermentation process in yeast buns. Using isotopic mass balance equations, the δ(13) C/δ(15) N values of multi-ingredient foods were estimated from the isotopic composition of constituent raw ingredients to within 0.14 ± 0.13‰/0.24 ± 0.17‰ for gravimetrically measured recipes and 0.40 ± 0.38‰/0.58 ± 0.53‰ for volumetrically measured recipes. Two common food preparation techniques, baking and fermentation, do not substantially affect the carbon or nitrogen isotopic signature of grain-based foods. Mass-balance equations can be used to

  15. Carbon and nitrogen stable isotope ratios of pelagic zooplankton elucidate ecohydrographic features in the oligotrophic Red Sea

    NASA Astrophysics Data System (ADS)

    Kürten, Benjamin; Al-Aidaroos, Ali M.; Kürten, Saskia; El-Sherbiny, Mohsen M.; Devassy, Reny P.; Struck, Ulrich; Zarokanellos, Nikolaos; Jones, Burton H.; Hansen, Thomas; Bruss, Gerd; Sommer, Ulrich

    2016-01-01

    Although zooplankton occupy key roles in aquatic biogeochemical cycles, little is known about the pelagic food web and trophodynamics of zooplankton in the Red Sea. Natural abundance stable isotope analysis (SIA) of carbon (δ13C) and N (δ15N) is one approach to elucidating pelagic food web structures and diet assimilation. Integrating the combined effects of ecological processes and hydrography, ecohydrographic features often translate into geographic patterns in δ13C and δ15N values at the base of food webs. This is due, for example, to divergent 15N abundances in source end-members (deep water sources: high δ15N, diazotrophs: low δ15N). Such patterns in the spatial distributions of stable isotope values were coined isoscapes. Empirical data of atmospheric, oceanographic, and biological processes, which drive the ecohydrographic gradients of the oligotrophic Red Sea, are under-explored and some rather anticipated than proven. Specifically, five processes underpin Red Sea gradients: (a) monsoon-related intrusions of nutrient-rich Indian Ocean water; (b) basin scale thermohaline circulation; (c) mesoscale eddy activity that causes up-welling of deep water nutrients into the upper layer; (d) the biological fixation of atmospheric nitrogen (N2) by diazotrophs; and (e) the deposition of dust and aerosol-derived N. This study assessed relationships between environmental samples (nutrients, chlorophyll a), oceanographic data (temperature, salinity, current velocity [ADCP]), particulate organic matter (POM), and net-phytoplankton, with the δ13C and δ15N values of zooplankton collected in spring 2012 from 16°28‧ to 26°57‧N along the central axis of the Red Sea. The δ15N of bulk POM and most zooplankton taxa increased from North (Duba) to South (Farasan). The potential contribution of deep water nutrient-fueled phytoplankton, POM, and diazotrophs varied among sites. Estimates suggested higher diazotroph contributions in the North, a greater contribution of

  16. Cross effect of temperature, pH and free ammonia on autotrophic denitrification process with sulphide as electron donor.

    PubMed

    Fajardo, Carmen; Mora, Mabel; Fernández, Isaac; Mosquera-Corral, Anuska; Campos, José Luis; Méndez, Ramón

    2014-02-01

    Autotrophic denitrification is a suitable technology to simultaneously remove oxidised nitrogen compounds and reduced sulphur compounds yielding nitrogen gas, sulphur and sulphate as the main products. In this work, several batch tests were conducted to investigate the cross effect of temperature, pH and free ammonia on the autotrophic denitrification. Denitrification efficiencies above 95% were achieved at 35°C and pH 7.5-8.0 with maximum specific autotrophic denitrifying activities up to 188mgN2g(-1)VSSd(-1). Free ammonia did not show any effect on denitrification at concentrations up to 53mg NH3-NL(-1). Different sulphide concentrations were also tested with stoichiometric nitrite and nitrate concentrations. Sulphide inhibited denitrification at concentrations higher than 200mgS(2-)L(-1). A 50% inhibition was also found at nitrite concentrations above 48mg NO2(-)-NL(-1). The maximum specific activity decreased until a value of 25mgN2g(-1) VSSd(-1) at 232mg NO2(-)-NL(-1). The Haldane model was used to describe denitrification inhibition caused by nitrite. Kinetic parameters determined from the fitting of experimental data were rmax=176mgN2g(-1)VSSd(-1), Ks=10.7mg NO2(-)-NL(-1) and Ki=34.7mg NO2(-)-NL(-1). The obtained model allowed optimising an autotrophic denitrification process by avoiding situations of inhibition and thus obtaining higher denitrification efficiencies. Copyright © 2013 Elsevier Ltd. All rights reserved.

  17. Effect of ecosystem retrogression on stable nitrogen and carbon isotopes of plants, soils and consumer organisms in boreal forest islands.

    PubMed

    Hyodo, Fujio; Wardle, David A

    2009-07-01

    In the prolonged absence of catastrophic disturbance, ecosystem retrogression occurs, and this involves increased nutrient limitation, and reduced aboveground and belowground ecosystem processes rates. Little is known about how the nitrogen and carbon stable isotope ratios (delta(15)N and delta(13)C) of plants, soils and consumer organisms respond to retrogression in boreal forests. We investigated a 5000 year chronosequence of forested islands in the boreal zone of northern Sweden, for which the time since lightning-induced wildfire increases with decreasing island size, leading to ecosystem retrogression. For this system, tissue delta(15)N of three abundant plant species (Betula pubescens, Vaccinium myrtillus and Pleurozium schreberi) and humus all increased as retrogression proceeded. This is probably due to enhanced ecosystem inputs of N by biological fixation, and greater dependency of the plants on organic N during retrogression. The delta(13)C of B. pubescens and plant-derived humus also increased during retrogression, probably through nutrient limitation increasing plant physiological stress. Unlike the plants, delta(15)N of invertebrates (lycosid spiders and ants) did not increase during retrogression, probably because of their partial dependence on aquatic-derived prey that had a variable delta(15)N signature. The delta(13)C of the invertebrates increased as retrogression proceeded and converged towards that of an aquatic prey source (chironomid flies), suggesting increased dependence on aquatic-derived prey during retrogression. These results show that measurement of delta(15)N and delta(13)C of plants, soils, and consumers across the same environmental gradient can provide insights into environmental factors that drive both the aboveground and belowground subsystems, as well as the linkages between them.

  18. Stable nitrogen isotope ratios and accumulation of PCDD/F and PCB in Baltic aquatic food chains

    SciTech Connect

    Broman, D.; Naef, C.; Rolff, C.; Zebuehr, Y.

    1994-12-31

    Ratios of naturally occurring stable isotopes of nitrogen ({delta}{sup 15}N) can be used to numerically classify trophic levels of organisms in food chains. By combining analyses results of PCDD/Fs and non-ortho PCBs the biomagnification of these substances can be quantitatively estimated. The two Baltic food chains studied were one pelagic (phytoplankton -- settling particulate matter (SPM) -- zooplankton -- mysids -- herring -- cod) and one littoral (phytoplankton -- SPM -- blue mussel -- eider duck). The {delta}{sup 15}N-data gave food chain descriptions qualitatively consistent with previous conceptions of trophic arrangements in the food chains. Phytoplankton showed the lowest average {delta}{sup 15}N-value and the juvenile eider duck and the cod showed the highest average {delta}{sup 15}N-values for the littoral and pelagic food chains, respectively. The PCDD/Fs and PCBs concentrations were plotted versus the {delta}{sup 15}N-values for the different trophic levels and an exponential model of the form e{sup (A + B*{delta}N)} was fitted to the data. The estimates of the constant B in the model allows for an estimation of a biomagnification power (B) of different singular, or groups of, contaminants. A B-value around zero indicates that a substance is flowing through the food chain without being magnified, whereas a value > 0 indicates that a substance is biomagnified. Negative B-values indicate that a substance is not taken up or is metabolized. The A-term of the expression is only a scaling factor depending on the background level of the contaminant.

  19. Trophic structure of mesopelagic fishes in the western Mediterranean based on stable isotopes of carbon and nitrogen

    NASA Astrophysics Data System (ADS)

    Valls, M.; Olivar, M. P.; Fernández de Puelles, M. L.; Molí, B.; Bernal, A.; Sweeting, C. J.

    2014-10-01

    Mesopelagic fishes play an important role in the transfer of organic material in the photic zone to depth although the trophodynamic partitioning amongst co-existing and presumably competing species is unclear. This study employs combined carbon and nitrogen stable isotope analyses (δ13C and δ15N) of the 18 most abundant western Mediterranean mesopelagic fishes to explore niche partitioning in this group. Sampling was conducted along the water column from the shelf and slope grounds of the Balearic Islands in two contrasting periods (late autumn and summer). Trophodynamics were explored at assemblage level and at inter- and intra-species resolutions respectively using Bayesian diet mixing models and size specific behaviour respectively. Seasonal δ13C differences in near basal particulate organic matter (POM) and zooplankton fractions were almost directly replicated in higher fauna suggesting strong isotopic coupling between mesopelagic fishes and planktonic production. Despite reliance on similar basal production, species were segregated by trophic position with a graduation from 2.9 for the small Gonostomatidae Cyclothone braueri to 4.0 for the Myctophidae Lobianchia dofleini. Mixing model data reflected basic trophic position estimates with higher contributions of small fish and zooplankton/POM in higher and lower trophic level species respectively. Species could be categorized as showing preference for i) mesozooplankton/POM as for C. braueri, (in the lower TrL), ii) euphausiids and fish prey as for L. dofleini and the near bottom Lampanyctus crocodilus (in the upper TrL) and iii) mesozooplankton/euphausiids as Ceratoscopelus maderensis, Lampanyctus pusillus or the migrating L. crocodilus. There was little evidence of size based inter-population trophodynamics, with size-isotope trends explained by co-varying lipid content.

  20. Nitrification and growth of autotrophic nitrifying bacteria and Thaumarchaeota in the coastal North Sea

    NASA Astrophysics Data System (ADS)

    Veuger, Bart; Pitcher, Angela; Schouten, Stefan; Sinninghe Damsté, Jaap S.; Middelburg, Jack J.

    2013-04-01

    A dual stable isotope (15N and 13C) tracer approach in combination with compound-specific stable isotope analysis of bacterial and Thaumarchaeotal lipid biomarkers was used to investigate nitrification and the associated growth of autotrophic nitrifiers in the Dutch coastal North Sea. This study focusses on the stoichiometry between nitrification and DIC fixation by autotrophic nitrifiers as well as on the contributions of bacteria versus Thaumarchaeota to total autotrophic DIC-fixation by nitrifiers. Water from the dutch coastal North Sea was collected at weekly to biweekly intervals during the winter of 2007-2008. Watersamples were incubated with 15N-labeled ammonium and 15N was traced into nitrate and suspended material to quantify rates of nitrification and ammonium assimilation respectively. Growth of autotrophic nitrifiers was measured by incubating water samples with 13C-DIC in the presence and absence of nitrification inhibitors (nitrapyrin and chlorate) and subsequent analysis of 13C in bacterial phospholipid-derived fatty acids (PLFAs) and the Thaumarchaeotal biomarker crenarchaeol. Results revealed high nitrification rates with nitrification being the primary sink for ammonium. 13C-DIC fixation into bacterial and Thaumarchaeotal lipids was strongly reduced by the nitrification inhibitors (27-95%). The ratio between rates of nitrification versus DIC fixation by nitrifiers was higher or even much higher than typical values for autotrophic nitrifiers, indicating that little DIC was fixed relative to the amount of energy that was generated by nitrification, and hence that other other processes for C acquisition may have been relevant as well. The inhibitor-sensitive 13C-PLFA pool was dominated by the common PLFAs 16:0, 16:1ω7c and 18:1ω7c throughout the whole sampling period and occasionally also included the polyunsaturated fatty acids 18:2ω6c and 18:3ω3. Cell-specific 13C-DIC fixation activity of the nitrifying bacteria was much higher than that of the

  1. Engineering the Autotroph Methanococcus maripaludis for Geraniol Production.

    PubMed

    Lyu, Zhe; Jain, Rachit; Smith, Peyton; Fetchko, Travis; Yan, Yajun; Whitman, William B

    2016-07-15

    The rapid autotrophic growth of the methanogenic archaeon Methanococcus maripaludis on H2 and CO2 makes it an attractive microbial chassis to inexpensively produce biochemicals. To explore this potential, a synthetic gene encoding geraniol synthase (GES) derived from Ocimum basilicum was cloned into a M. maripaludis expression vector under selection for puromycin resistance. Recombinant expression of GES in M. maripaludis during autotrophic growth on H2/CO2 or formate yielded geraniol at 2.8 and 4.0 mg g(-1) of dry weight, respectively. The yield of geraniol decreased 2-3-fold when organic carbon sources were added to stimulate heterotrophic growth. In the absence of puromycin, geraniol production during autotrophic growth on formate increased to 4.6 mg g(-1) of dry weight. A conceptual model centered on the autotrophic acetyl coenzyme A biosynthetic pathway identified strategies to divert more autotrophic carbon flux to geraniol production.

  2. Sulfur-driven autotrophic denitrification: diversity, biochemistry, and engineering applications.

    PubMed

    Shao, Ming-Fei; Zhang, Tong; Fang, Herbert Han-Ping

    2010-11-01

    Sulfur-driven autotrophic denitrification refers to the chemolithotrophic process coupling denitrification with the oxidation of reduced inorganic sulfur compounds. Ever since 1904, when Thiobacillus denitrificans was isolated, autotrophic denitrifiers and their uncultured close relatives have been continuously identified from highly diverse ecosystems including hydrothermal vents, deep sea redox transition zones, sediments, soils, inland soda lakes, etc. Currently, 14 valid described species within α-, β-, γ-, and ε-Proteobacteria have been identified as capable of autotrophic denitrification. Autotrophic denitrification is also widely applied in environmental engineering for the removal of sulfide and nitrate from different water environments. This review summarizes recent researches on autotrophic denitrification, highlighting its diversity, metabolic traits, and engineering applications.

  3. Isolation of an autotrophic ammonia-oxidizing marine archaeon.

    PubMed

    Könneke, Martin; Bernhard, Anne E; de la Torre, José R; Walker, Christopher B; Waterbury, John B; Stahl, David A

    2005-09-22

    For years, microbiologists characterized the Archaea as obligate extremophiles that thrive in environments too harsh for other organisms. The limited physiological diversity among cultivated Archaea suggested that these organisms were metabolically constrained to a few environmental niches. For instance, all Crenarchaeota that are currently cultivated are sulphur-metabolizing thermophiles. However, landmark studies using cultivation-independent methods uncovered vast numbers of Crenarchaeota in cold oxic ocean waters. Subsequent molecular surveys demonstrated the ubiquity of these low-temperature Crenarchaeota in aquatic and terrestrial environments. The numerical dominance of marine Crenarchaeota--estimated at 10(28) cells in the world's oceans--suggests that they have a major role in global biogeochemical cycles. Indeed, isotopic analyses of marine crenarchaeal lipids suggest that these planktonic Archaea fix inorganic carbon. Here we report the isolation of a marine crenarchaeote that grows chemolithoautotrophically by aerobically oxidizing ammonia to nitrite--the first observation of nitrification in the Archaea. The autotrophic metabolism of this isolate, and its close phylogenetic relationship to environmental marine crenarchaeal sequences, suggests that nitrifying marine Crenarchaeota may be important to global carbon and nitrogen cycles.

  4. Autotrophic denitrification for combined hydrogen sulfide removal from biogas and post-denitrification.

    PubMed

    Kleerebezem, R; Mendez, R

    2002-01-01

    In this paper we describe an alternative flow-chart for full treatment of wastewaters rich in organic substrates, ammonia (or organic nitrogen), and sulfate, such as those generated in fish cannery industries. Biogas generated during anaerobic pretreatment of these wastewaters is rich in hydrogen sulfide that needs to be removed to enable application of the biogas. Nitrogen elimination is traditionally achieved by subsequent nitrification and denitrification of the effluent of the anaerobic reactor. Alternatively, the hydrogen sulfide in the biogas can be applied as an electron donor in an autotrophic post-denitrification step. In order to study whether sufficient hydrogen sulfide containing biogas for denitrification was produced in the anaerobic reactor, the biogas composition as a function of the anaerobic reactor-pH was estimated based on a typical wastewater composition and chemical equilibrium equations. It is demonstrated that typical sulfate and nitrogen concentrations in fish cannery wastewater are highly appropriate for application of autotrophic post-denitrification. A literature review furthermore suggested that the kinetic parameters for autotrophic denitrification by Thiobacillus denitrificans represent no bottleneck for its application. Initial experimental studies in fixed-film reactors were conducted with sodium sulfide and nitrate as an electron donor-acceptor couple. The results revealed that only moderate volumetric treatment capacities (< 1 g-NO3- N l(-1) day(-1)) could be achieved. Mass balances suggested that incomplete sulfide oxidation to elemental sulfur occurred, limiting biomass retention and the treatment capacity of the reactor. Future research should clarify the questions concerning product formation from sulfide oxidation.

  5. The Stable Level of Glutamine synthetase 2 Plays an Important Role in Rice Growth and in Carbon-Nitrogen Metabolic Balance.

    PubMed

    Bao, Aili; Zhao, Zhuqing; Ding, Guangda; Shi, Lei; Xu, Fangsen; Cai, Hongmei

    2015-06-04

    Glutamine synthetase 2 (GS2) is a key enzyme involved in the ammonium metabolism in plant leaves. In our previous study, we obtained GS2-cosuppressed plants, which displayed a normal growth phenotype at the seedling stage, while at the tillering stage they showed a chlorosis phenotype. In this study, to investigate the chlorosis mechanism, we systematically analyzed the plant growth, carbon-nitrogen metabolism and gene expressions between the GS2-cosuppressed rice and wild-type plants. The results revealed that the GS2-cosuppressed plants exhibited a poor plant growth phenotype and a poor nitrogen transport ability, which led to nitrogen accumulation and a decline in the carbon/nitrogen ratio in the stems. Interestingly, there was a higher concentration of soluble proteins and a lower concentration of carbohydrates in the GS2-cosuppressed plants at the seedling stage, while a contrasting result was displayed at the tillering stage. The analysis of the metabolic profile showed a significant increase of sugars and organic acids. Additionally, gene expression patterns were different in root and leaf of GS2-cosuppressed plants between the seedling and tillering stage. These results indicated the important role of a stable level of GS2 transcription during normal rice development and the importance of the carbon-nitrogen metabolic balance in rice growth.

  6. The Stable Level of Glutamine synthetase 2 Plays an Important Role in Rice Growth and in Carbon-Nitrogen Metabolic Balance

    PubMed Central

    Bao, Aili; Zhao, Zhuqing; Ding, Guangda; Shi, Lei; Xu, Fangsen; Cai, Hongmei

    2015-01-01

    Glutamine synthetase 2 (GS2) is a key enzyme involved in the ammonium metabolism in plant leaves. In our previous study, we obtained GS2-cosuppressed plants, which displayed a normal growth phenotype at the seedling stage, while at the tillering stage they showed a chlorosis phenotype. In this study, to investigate the chlorosis mechanism, we systematically analyzed the plant growth, carbon-nitrogen metabolism and gene expressions between the GS2-cosuppressed rice and wild-type plants. The results revealed that the GS2-cosuppressed plants exhibited a poor plant growth phenotype and a poor nitrogen transport ability, which led to nitrogen accumulation and a decline in the carbon/nitrogen ratio in the stems. Interestingly, there was a higher concentration of soluble proteins and a lower concentration of carbohydrates in the GS2-cosuppressed plants at the seedling stage, while a contrasting result was displayed at the tillering stage. The analysis of the metabolic profile showed a significant increase of sugars and organic acids. Additionally, gene expression patterns were different in root and leaf of GS2-cosuppressed plants between the seedling and tillering stage. These results indicated the important role of a stable level of GS2 transcription during normal rice development and the importance of the carbon-nitrogen metabolic balance in rice growth. PMID:26053400

  7. Bulk vs. amino acid stable N isotope estimations of metabolic status and contributions of nitrogen fixation to size-fractionated zooplankton biomass in the subtropical N Atlantic

    NASA Astrophysics Data System (ADS)

    Mompeán, Carmen; Bode, Antonio; Gier, Elizabeth; McCarthy, Matthew D.

    2016-08-01

    A comparative analysis of natural abundance of stable N isotopes (δ15N) in individual amino acids and bulk organic matter of size-fractionated plankton revealed the differential impact of nitrogen fixation through the food web in a transect across the subtropical North Atlantic. All δ15N measurements showed low values in the central region, followed by the western zone, while maximum δ15N values were found in the eastern zone. These results were consistent with the prevalence of nitrogen fixation in the central and western zones, and the influence of the west Africa upwelling in the eastern zone. Use of compound-specific amino acid isotope data (CSI-AA) revealed relatively low variability in the impact of diazotrophic nitrogen within the different plankton size fractions, while δ15N of bulk organic matter showed high variability with size. Explicit CSI-AA trophic position estimates showed a small increase with mean plankton size class and varied in a relatively narrow range 1.8-2.5), with the lowest values in the central zone. High correlations between bulk plankton δ15N and individual amino acids (in particular Phe and Thr), as well as reconstructed total protein δ15N values, suggest a set of new relationships that may be important to tracing direct plankton contributions to nitrogen recycling in the ocean, including detrital organic nitrogen pools. Overall, these new results represent the most detailed investigation of CSI-AA data in plankton size classes to date, and indicated a greater importance of diazotrophic N than suggested by concurrent measurements of bulk δ15N, abundance of large nitrogen fixing organisms or nitrogen fixation rates.

  8. Use of stable carbon and nitrogen isotopes to trace the larval striped bass food chain in the Sacramento-San Joaquin Estuary, California, April to September 1985

    USGS Publications Warehouse

    Rast, Walter; Sutton, J.E.

    1989-01-01

    To assess one potential cause for the decline of the striped bass fishery in the Sacramento-San Joaquin Estuary, stable carbon and nitrogen isotope ratios were used to examine the trophic structures of the larval striped bass food chain, and to trace the flux of these elements through the food chain components. Study results generally confirm a food chain consisting of the elements, phytoplankton/detritus-->zooplankton/Neomysis shrimp-->larval striped bass. The stable isotope ratios generally become more positive as one progresses from the lower to the higher trophic level food chain components, and no unusual trophic structure was found in the food chain. However, the data indicate an unidentified consumer organism occupying an intermediate position between the lower and higher trophic levels of the larval striped bass food chain. Based on expected trophic interactions, this unidentified consumer would have a stable carbon isotope ratio of about 28/mil and a stable nitrogen isotope ratio of about 8/mi. Three possible feeding stages for larval striped bass also were identified, based on their lengths. The smallest length fish seem to subsist on their yolk sac remnants, and the largest length fish subsist on Neomysis shrimp and zooplankton. The intermediate-length fish represent a transition stage between primary food sources and/or use of a mixture of food sources. (USGS)

  9. Apparatus and method for controlling autotroph cultivation

    DOEpatents

    Fuxman, Adrian M; Tixier, Sebastien; Stewart, Gregory E; Haran, Frank M; Backstrom, Johan U; Gerbrandt, Kelsey

    2013-07-02

    A method includes receiving at least one measurement of a dissolved carbon dioxide concentration of a mixture of fluid containing an autotrophic organism. The method also includes determining an adjustment to one or more manipulated variables using the at least one measurement. The method further includes generating one or more signals to modify the one or more manipulated variables based on the determined adjustment. The one or more manipulated variables could include a carbon dioxide flow rate, an air flow rate, a water temperature, and an agitation level for the mixture. At least one model relates the dissolved carbon dioxide concentration to one or more manipulated variables, and the adjustment could be determined by using the at least one model to drive the dissolved carbon dioxide concentration to at least one target that optimize a goal function. The goal function could be to optimize biomass growth rate, nutrient removal and/or lipid production.

  10. Dense autotrophic cultures of Alcaligenes eutrophus.

    PubMed Central

    Repaske, R; Mayer, R

    1976-01-01

    Alcaligenes eutrophus was grown autotrophically in 23-liter batch cultures in a controlled H2-O2-CO2 atmosphere. It was demonstrated that the need for periodic supplements of individual nutrients could be anticipated before cell growth depleted these nutrients to the point of becoming growth rate limiting. As a result, exponential growth was extended to optical densities of 44, with doubling times maintained at 2 h. Cultures having an initial optical density of 0.040 to 0.70 reached the final optical density of 60 in about 25 h. The final viable count was 1.2 X 10(11) cells per ml, and the dry weight was 25 g/liter. PMID:10840

  11. Soil respiration under climate warming: differential response of heterotrophic and autotrophic respiration.

    PubMed

    Wang, Xin; Liu, Lingli; Piao, Shilong; Janssens, Ivan A; Tang, Jianwu; Liu, Weixing; Chi, Yonggang; Wang, Jing; Xu, Shan

    2014-10-01

    Despite decades of research, how climate warming alters the global flux of soil respiration is still poorly characterized. Here, we use meta-analysis to synthesize 202 soil respiration datasets from 50 ecosystem warming experiments across multiple terrestrial ecosystems. We found that, on average, warming by 2 °C increased soil respiration by 12% during the early warming years, but warming-induced drought partially offset this effect. More significantly, the two components of soil respiration, heterotrophic respiration and autotrophic respiration showed distinct responses. The warming effect on autotrophic respiration was not statistically detectable during the early warming years, but nonetheless decreased with treatment duration. In contrast, warming by 2 °C increased heterotrophic respiration by an average of 21%, and this stimulation remained stable over the warming duration. This result challenged the assumption that microbial activity would acclimate to the rising temperature. Together, our findings demonstrate that distinguishing heterotrophic respiration and autotrophic respiration would allow us better understand and predict the long-term response of soil respiration to warming. The dependence of soil respiration on soil moisture condition also underscores the importance of incorporating warming-induced soil hydrological changes when modeling soil respiration under climate change. © 2014 John Wiley & Sons Ltd.

  12. Dose-dependent response of nitrogen stable isotope ratio to proportion of legumes in diet to authenticate lamb meat produced from legume-rich diets.

    PubMed

    Devincenzi, T; Delfosse, O; Andueza, D; Nabinger, C; Prache, S

    2014-01-01

    This study investigated the dose-dependent response in lamb meat of stable nitrogen isotope ratio to the dietary proportion of legumes, and the ability of the nitrogen isotope signature of the meat to authenticate meat produced from legume-rich diets. Four groups of nine male Romane lambs grazing a cocksfoot pasture were supplemented with different levels of fresh alfalfa forage to obtain four dietary proportions of alfalfa (0%, 25%, 50% and 75%) for 98 days on average before slaughter (groups L0, L25, L50 and L75). We measured the stable nitrogen isotope ratio in the forages and in the longissimus thoracis muscle. The δ(15)N value of the meat decreased linearly with the dietary proportion of alfalfa. The distribution of the δ(15)N values of the meat discriminated all the L0 lambs from the L75 lambs, and gave a correct classification score of 85.3% comparing lambs that ate alfalfa with those that did not.

  13. The stable isotope composition of nitrogen and carbon and elemental contents in modern and fossil seabird guano from Northern Chile - Marine sources and diagenetic effects.

    PubMed

    Lucassen, Friedrich; Pritzkow, Wolfgang; Rosner, Martin; Sepúlveda, Fernando; Vásquez, Paulina; Wilke, Hans; Kasemann, Simone A

    2017-01-01

    Seabird excrements (guano) have been preserved in the arid climate of Northern Chile since at least the Pliocene. The deposits of marine organic material in coastal areas potentially open a window into the present and past composition of the coastal ocean and its food web. We use the stable isotope composition of nitrogen and carbon as well as element contents to compare the principal prey of the birds, the Peruvian anchovy, with the composition of modern guano. We also investigate the impact of diagenetic changes on the isotopic composition and elemental contents of the pure ornithogenic sediments, starting with modern stratified deposits and extending to fossil guano. Where possible, 14C systematics is used for age information. The nitrogen and carbon isotopic composition of the marine prey (Peruvian anchovy) of the birds is complex as it shows strong systematic variations with latitude. The detailed study of a modern profile that represents a few years of guano deposition up to present reveals systematic changes in nitrogen and carbon isotopic composition towards heavier values that increase with age, i.e. depth. Only the uppermost, youngest layers of modern guano show compositional affinity to the prey of the birds. In the profile, the simultaneous loss of nitrogen and carbon occurs by degassing, and non-volatile elements like phosphorous and calcium are passively enriched in the residual guano. Fossil guano deposits are very low in nitrogen and low in carbon contents, and show very heavy nitrogen isotopic compositions. One result of the study is that the use of guano for tracing nitrogen and carbon isotopic and elemental composition in the marine food web of the birds is restricted to fresh material. Despite systematic changes during diagenesis, there is little promise to retrieve reliable values of marine nitrogen and carbon signatures from older guano. However, the changes in isotopic composition from primary marine nitrogen isotopic signatures towards very

  14. The stable isotope composition of nitrogen and carbon and elemental contents in modern and fossil seabird guano from Northern Chile – Marine sources and diagenetic effects

    PubMed Central

    Pritzkow, Wolfgang; Rosner, Martin; Sepúlveda, Fernando; Vásquez, Paulina; Wilke, Hans; Kasemann, Simone A.

    2017-01-01

    Seabird excrements (guano) have been preserved in the arid climate of Northern Chile since at least the Pliocene. The deposits of marine organic material in coastal areas potentially open a window into the present and past composition of the coastal ocean and its food web. We use the stable isotope composition of nitrogen and carbon as well as element contents to compare the principal prey of the birds, the Peruvian anchovy, with the composition of modern guano. We also investigate the impact of diagenetic changes on the isotopic composition and elemental contents of the pure ornithogenic sediments, starting with modern stratified deposits and extending to fossil guano. Where possible, 14C systematics is used for age information. The nitrogen and carbon isotopic composition of the marine prey (Peruvian anchovy) of the birds is complex as it shows strong systematic variations with latitude. The detailed study of a modern profile that represents a few years of guano deposition up to present reveals systematic changes in nitrogen and carbon isotopic composition towards heavier values that increase with age, i.e. depth. Only the uppermost, youngest layers of modern guano show compositional affinity to the prey of the birds. In the profile, the simultaneous loss of nitrogen and carbon occurs by degassing, and non-volatile elements like phosphorous and calcium are passively enriched in the residual guano. Fossil guano deposits are very low in nitrogen and low in carbon contents, and show very heavy nitrogen isotopic compositions. One result of the study is that the use of guano for tracing nitrogen and carbon isotopic and elemental composition in the marine food web of the birds is restricted to fresh material. Despite systematic changes during diagenesis, there is little promise to retrieve reliable values of marine nitrogen and carbon signatures from older guano. However, the changes in isotopic composition from primary marine nitrogen isotopic signatures towards very

  15. Efficient total nitrogen removal in an ammonia gas biofilter through high-rate OLAND.

    PubMed

    De Clippeleir, Haydée; Courtens, Emilie; Mosquera, Mariela; Vlaeminck, Siegfried E; Smets, Barth F; Boon, Nico; Verstraete, Willy

    2012-08-21

    Ammonia gas is conventionally treated in nitrifying biofilters; however, addition of organic carbon to perform post-denitrification is required to obtain total nitrogen removal. Oxygen-limited autotrophic nitrification/denitrification (OLAND), applied in full-scale for wastewater treatment, can offer a cost-effective alternative for gas treatment. In this study, the OLAND application thus was broadened toward ammonia loaded gaseous streams. A down flow, oxygen-saturated biofilter (height of 1.5 m; diameter of 0.11 m) was fed with an ammonia gas stream (248 ± 10 ppmv) at a loading rate of 0.86 ± 0.04 kg N m(-3) biofilter d(-1) and an empty bed residence time of 14 s. After 45 days of operation a stable nitrogen removal rate of 0.67 ± 0.06 kg N m(-3) biofilter d(-1), an ammonia removal efficiency of 99%, a removal of 75-80% of the total nitrogen, and negligible NO/N(2)O productions were obtained at water flow rates of 1.3 ± 0.4 m(3) m(-2) biofilter section d(-1). Profile measurements revealed that 91% of the total nitrogen activity was taking place in the top 36% of the filter. This study demonstrated for the first time highly effective and sustainable autotrophic ammonia removal in a gas biofilter and therefore shows the appealing potential of the OLAND process to treat ammonia containing gaseous streams.

  16. Nitrogen fixation by hydrogen-utilizing bacteria.

    PubMed

    De Bont, J A; Leijten, M W

    1976-04-01

    Seventeen strains of nitrogen-fixing bacteria, isolated from different habitats on hydrogen and carbon dioxide as well as on other substrates, morphologically resembled each other. All strains, including Mycobacterium flavum 301, grew autotrophically with hydrogen. The isolate strain 6 was sensitive to oxygen when dependent on N2 as nitrogen source, a consequence of the sensitivity of its nitrogenase towards oxygen. At the same time, strain 6 was sensitive to hydrogen when growing autotrophically on N2 as nitrogen source, but hydrogen did not affect acetylene reduction by these cells.

  17. Source apportionment of atmospheric ammonia before, during, and after the 2014 APEC summit in Beijing using stable nitrogen isotope signatures

    NASA Astrophysics Data System (ADS)

    Chang, Yunhua; Liu, Xuejun; Deng, Congrui; Dore, Anthony J.; Zhuang, Guoshun

    2016-09-01

    Stable nitrogen isotope composition (δ15N) offers new opportunities to address the long-standing and ongoing controversy regarding the origins of ambient ammonia (NH3), a vital precursor of PM2.5 (particulate matters with aerodynamic diameter equal or less than 2.5 µm) inorganic components, in the urban atmosphere. In this study, the δ15N values of NH3 samples collected from various sources were constrained using a novel and robust chemical method coupled with standard elemental analysis procedures. Independent of the wide variation in mass concentrations (ranging from 33 (vehicle) to over 6000 (human excreta) µg m-3), different NH3 sources have generally different δ15N values (ranging from -52.0 to -9.6 ‰). Significantly high δ15N values are seen as a characteristic feature of all vehicle-derived NH3 samples (-14.2 ± 2.8 ‰), which can be distinguished from other sources emitted at environmental temperature (-29.1 ± 1.7, -37.8 ± 3.6, and -50.0 ± 1.8 ‰ for livestock, waste, and fertilizer, respectively). The isotope δ15N signatures for a range of NH3 emission sources were used to evaluate the contributions of the different sources within measured ambient NH3 in Beijing, using an isotope mixing model (IsoSource). The method was used to quantify the sources of ambient NH3 before, during and after the 2014 Asia-Pacific Economic Cooperation (APEC) summit, when a set of stringent air quality control measures were implemented. Results show that the average NH3 concentrations (the overall contributions of traffic, waste, livestock, and fertilizer) during the three periods were 9.1 (20.3, 28.3, 23.6, and 27.7 %), 7.3 (8.8, 24.9, 14.3, and 52.0 %), and 12.7 (29.4, 23.6, 31.7, and 15.4 %) µg m-3, respectively, representing a 20.0 % decrease first and then a 74.5 % increase in overall NH3 mass concentrations. During (after) the summit, the contributions of traffic, waste, livestock, and fertilizer decreased (increased) by 56.7 (234.2), 12.0 (-5.0), 39.4 (120

  18. An Experiment in Autotrophic Fermentation: Microbial Oxidation of Hydrogen Sulfide.

    ERIC Educational Resources Information Center

    Sublette, Kerry L.

    1989-01-01

    Described is an experiment which uses an autotrophic bacterium to anaerobically oxidize hydrogen sulfide to sulfate in a batch-stirred tank reactor. Discusses background information, experimental procedure, and sample results of this activity. (CW)

  19. Comparative lipid composition of heterotrophically and autotrophically grown Sulfolobus acidocaldarius.

    PubMed

    Langworthy, T A

    1977-06-01

    Complex lipids from the thermoacidophilic facultative autotroph Sulfolobus acidocaldarius, as well as a strictly autotrophic isolate, were compared between cells grown on yeast extract and elemental sulfur. Lipids from both organisms grown autotrophically were nearly identical. Each contained about 15% neutral lipids, 35% glycolipids, and 50% acidic lipids. Glycolipids and acidic lipids contained C40H82-76-derived glycerol ether residues. Major glycolipids included the glycerol ether analogues of glucosyl galactosyl diglyceride (5%) and glucosyl polyol diglyceride (75%). Acidic lipids were comprised mainly of the glycerol ether analogues of phosphatidyl inositol (7%), inositolphosphoryl glucosyl polyol diglyceride (72%), and a partially characterized sulfate- and phosphate-containing derivative of glucosyl polyol diglyceride (13%). The lipids from cells grown heterotrophically were similar to those from autotrophically grown cells, except that the partially characterized acidic lipid was absent. In addition, the two glycolipids as well as the respective inositolphosphoryl derivatives were each present in nearly equal proportions.

  20. Comparative lipid composition of heterotrophically and autotrophically grown Sulfolobus acidocaldarius.

    PubMed Central

    Langworthy, T A

    1977-01-01

    Complex lipids from the thermoacidophilic facultative autotroph Sulfolobus acidocaldarius, as well as a strictly autotrophic isolate, were compared between cells grown on yeast extract and elemental sulfur. Lipids from both organisms grown autotrophically were nearly identical. Each contained about 15% neutral lipids, 35% glycolipids, and 50% acidic lipids. Glycolipids and acidic lipids contained C40H82-76-derived glycerol ether residues. Major glycolipids included the glycerol ether analogues of glucosyl galactosyl diglyceride (5%) and glucosyl polyol diglyceride (75%). Acidic lipids were comprised mainly of the glycerol ether analogues of phosphatidyl inositol (7%), inositolphosphoryl glucosyl polyol diglyceride (72%), and a partially characterized sulfate- and phosphate-containing derivative of glucosyl polyol diglyceride (13%). The lipids from cells grown heterotrophically were similar to those from autotrophically grown cells, except that the partially characterized acidic lipid was absent. In addition, the two glycolipids as well as the respective inositolphosphoryl derivatives were each present in nearly equal proportions. Images PMID:863856

  1. An Experiment in Autotrophic Fermentation: Microbial Oxidation of Hydrogen Sulfide.

    ERIC Educational Resources Information Center

    Sublette, Kerry L.

    1989-01-01

    Described is an experiment which uses an autotrophic bacterium to anaerobically oxidize hydrogen sulfide to sulfate in a batch-stirred tank reactor. Discusses background information, experimental procedure, and sample results of this activity. (CW)

  2. Beyond the Calvin cycle: autotrophic carbon fixation in the ocean.

    PubMed

    Hügler, Michael; Sievert, Stefan M

    2011-01-01

    Organisms capable of autotrophic metabolism assimilate inorganic carbon into organic carbon. They form an integral part of ecosystems by making an otherwise unavailable form of carbon available to other organisms, a central component of the global carbon cycle. For many years, the doctrine prevailed that the Calvin-Benson-Bassham (CBB) cycle is the only biochemical autotrophic CO2 fixation pathway of significance in the ocean. However, ecological, biochemical, and genomic studies carried out over the last decade have not only elucidated new pathways but also shown that autotrophic carbon fixation via pathways other than the CBB cycle can be significant. This has ramifications for our understanding of the carbon cycle and energy flow in the ocean. Here, we review the recent discoveries in the field of autotrophic carbon fixation, including the biochemistry and evolution of the different pathways, as well as their ecological relevance in various oceanic ecosystems.

  3. Beyond the Calvin Cycle: Autotrophic Carbon Fixation in the Ocean

    NASA Astrophysics Data System (ADS)

    Hügler, Michael; Sievert, Stefan M.

    2011-01-01

    Organisms capable of autotrophic metabolism assimilate inorganic carbon into organic carbon. They form an integral part of ecosystems by making an otherwise unavailable form of carbon available to other organisms, a central component of the global carbon cycle. For many years, the doctrine prevailed that the Calvin-Benson-Bassham (CBB) cycle is the only biochemical autotrophic CO2 fixation pathway of significance in the ocean. However, ecological, biochemical, and genomic studies carried out over the last decade have not only elucidated new pathways but also shown that autotrophic carbon fixation via pathways other than the CBB cycle can be significant. This has ramifications for our understanding of the carbon cycle and energy flow in the ocean. Here, we review the recent discoveries in the field of autotrophic carbon fixation, including the biochemistry and evolution of the different pathways, as well as their ecological relevance in various oceanic ecosystems.

  4. Discrimination factors of carbon and nitrogen stable isotopes from diet to hair and scat in captive tigers (Panthera tigris) and snow leopards (Uncia uncia).

    PubMed

    Montanari, Shaena; Amato, George

    2015-06-15

    In order to use stable isotope ratio values obtained from wild animal tissues, we must accurately calculate the differences in isotope ratios between diet and consumer (δtissue - δdiet). These values, called trophic discrimination factors (TDFs, denoted with ∆), are necessary for stable isotope ecology studies and are best calculated in controlled environments. Scat, hair, and diet samples were collected from captive tigers (n = 8) and snow leopards (n = 10) at the Bronx Zoo. The isotope ratios of carbon and nitrogen, the two most commonly used in ecological studies, of the samples were measured by continuous-flow isotope ratio mass spectrometry. The trophic discrimination factors were calculated for both carbon (δ(13)C values) and nitrogen (δ(15)N values). It was found that the only significant TDFs in this study were diet-hair, ∆(13)CHair, for snow leopards (5.97 ± 1.25‰) and tigers (6.45 ± 0.54‰), and diet-scat, ∆(15)NScat, in snow leopards (2.49 ± 1.30‰). The other mean isotope ratios were not significantly different from that of the premixed feline diet. The ∆(15)NHair values for both species were unusually low, potentially due to the protein content and quality of the feline diet. The discrimination factors of the stable isotopes of carbon and nitrogen calculated in this study can be applied to ecological studies of wild, non-captive terrestrial mammals. The effect of protein quality in isotope discrimination is also worthy of further investigation to better understand variation in TDFs. Carnivore scat is shown to be a valuable material for isotopic analysis. Copyright © 2015 John Wiley & Sons, Ltd.

  5. Investigation of the nitrogen hyperfine coupling of the second stable radical in γ-irradiated L-alanine crystals by 2D-HYSCORE spectroscopy

    NASA Astrophysics Data System (ADS)

    Maltar-Strmečki, Nadica; Rakvin, Boris

    2012-09-01

    The second stable radical, NH3+C(CH3)COO, R2, in the γ-irradiated single crystal of L-alanine and its fully 15N-enriched analogue were studied by an advanced pulsed EPR technique, 2D-HYSCORE (two-dimensional hyperfine sublevel correlation) spectroscopy at 200 K. The nitrogen hyperfine coupling tensor of the R2 radical was determined from the HYSCORE data and provides new experimental data for improved characterization of the R2 radical in the crystal lattice. The results obtained complement the experimental proton data available for the R2 radical and could lead to increased accuracy and reliability of EPR spectrum simulations.

  6. SPATIAL AND TEMPROAL RELATIONSHIPS BETWEEN TOTAL NITROGEN AND PALNKTONIC CHLOROPHYLL IN LONG ISLAND SOUND: HOW STABLE ARE THEY?

    EPA Science Inventory

    Our purpose is to examine seasonal and year-to-year variability of relationships between concentrations of total nitrogen and chlorophyll in the water column of an estuary. Understanding this variability gives guidance to those developing methods to assess risk of eutrophication ...

  7. [Nitrogen concentrations and stable isotope in epilithic mosses to investigate atmospheric N deposition and N sources in Jiangxi Province].

    PubMed

    Xie, Zhi-Ying; Xiao, Hua-Yun; Zhu, Ren-Guo; Wu, Dai-She

    2011-04-01

    Atmospheric N deposition and N sources in Jiangxi Province were investigated on the basis of the nitrogen concentrations and nitrogen isotope in epilithic mosses which collected from 11 cities of the province during 2009-2010. Mean nitrogen concentrations ranged from 2.46% to 3.48% and showed a significant regional difference. The highest was found in the northwestern of the province and the lowest in the southeastern, reflecting that the level of the atmospheric N deposition gradually decreased from the north to the south in the province. The higher N concentrations in urban mosses than in suburban mosses indicated that the urban areas received higher rates of nitrogen deposition than suburbs areas. Mosses 15N values varied from (-9.74 +/- 0.25) per thousand to (-1.96 +/- 1.30) per thousand. More negative delta15N values of urban mosses (-5.51 per thousand-9.74 per thousand) indicated that more NH3 was released from excretory wastes and sewage, while less negative delta15N values of suburban mosses (-4.81 per thousand-1.96 per thousand) suggested an important contribution from agricultural NH3 emission due to intensive fertilizer application. This research provides basic information for further study on the ecological and environmental effects of atmospheric N deposition.

  8. Nitrogen-fixing symbiosis inferred from stable isotope analysis of fossil tree rings from the Oligocene of Ethiopia

    Treesearch

    Erik L. Gulbranson; Bonnie F. Jacobs; William C. Hockaday; Michael C. Wiemann; Lauren A. Michel; Kaylee Richards; John W. Kappelman

    2017-01-01

    The acquisition of reduced nitrogen (N) is essential for plant life, and plants have developed numerous strategies and symbioses with soil microorganisms to acquire this form of N. The evolutionary history of specific symbiotic relationships of plants with soil bacteria, however, lacks evidence from the fossil record confirming these mutualistic relationships. Here we...

  9. STUDIES ON THE METABOLISM OF AUTOTROPHIC BACTERIA

    PubMed Central

    Vogler, K. G.; LePage, G. A.; Umbreit, W. W.

    1942-01-01

    The data of this paper indicate that: 1. The "energy of activation" (µ) of sulfur oxidation by the autotrophic bacterium, Thiobacillus thiooxidans, is similar to that of other respirations. 2. The pH of the menstruum does not influence the respiration on sulfur between the limits of pH 2 to 4.8 once contact between the bacterial cell and the sulfur particle has been established but it does influence the rate at which such contact occurs. 3. The pO2 has little effect upon the respiration of this organism. 4. Most organic materials have no detectable effect upon the respiration of Thiobacillus thiooxidans, but the organic acids of terminal respiration seem to stimulate the respiration in the absence of oxidizable sulfur and certain of them inhibit sulfur oxidation. 5. In so far as inhibitor studies on intact cells are trustworthy, sulfur oxidation goes through iron-containing systems similar to cytochrome. It is possible that the oxygen contained in the sulfuric acid formed during sulfur oxidation is derived from the oxygen of the water. PMID:19873331

  10. Establishment of trophic continuum in the food web of the Yellow Sea and East China Sea ecosystem: insight from carbon and nitrogen stable isotopes.

    PubMed

    Cai, Deling; Li, Hongyan; Tang, Qisheng; Sun, Yao

    2005-12-01

    Stable carbon and nitrogen isotope ratios (delta (13)C and delta (15)N) are used to study the trophic structure of food web in the Yellow Sea and East China Sea ecosystem. The trophic continuum of pelagic food web from phytoplankton to top preyer was elementarily established, and a trophic structure diagram in the Yellow Sea and East China Sea was outlined in combination with carbon isotopic data of benthic organisms, which is basically consistent with and makes some improvements on the simplified Yellow Sea food web and the trophic structure diagram drawn based on the biomass of main resource population during 1985-1986. This result indicates that the stable isotope method is a potential useful means for further studying the complete marine food web trophic continuum from viruses to top predators and food web stability.

  11. Identifying nitrogen sources to thermal tide pools in Kapoho, Hawai'i, U.S.A, using a multi-stable isotope approach.

    PubMed

    Wiegner, Tracy N; Mokiao-Lee, Ambyr U; Johnson, Erik E

    2016-02-15

    Nitrogen (N) enrichment often results in coastal eutrophication, even in remote areas like Hawai'i. Therefore, determining N sources to coastal waters is important for their management. This study identified N sources to tide pools in Kapoho, Hawai'i, and determined their relative importance using three stable isotopes (δ(15)N, δ(18)O, δ(11)B). Surface waters and macroalgal tissues were collected along 100-m onshore-offshore transects in areas of high groundwater input for three months at low tide. Water samples from possible N sources were also collected. Mixing model output, along with macroalgal δ(15)N values, indicated that agriculture soil (34%) was the largest anthropogenic N source followed by sewage (27%). These findings suggest that more effective fertilizer application techniques and upgrading sewage treatment systems can minimize N leaching into groundwater. Overall, our multi-stable isotope approach for identifying N sources was successful and may be useful in other coastal waters.

  12. Linking autotrophic activity in environmental samples with specific bacterial taxa by detection of 13C-labelled fatty acids.

    PubMed

    Knief, Claudia; Altendorf, Karlheinz; Lipski, André

    2003-11-01

    A method for the detection of physiologically active autotrophic bacteria in complex microbial communities was developed based on labelling with the stable isotope 13C. Labelling of autotrophic nitrifying, sulphur-oxidizing and iron-oxidizing populations was performed in situ by incubation with NaH[13C]O3. Incorporated label into fatty acid methyl esters (FAMEs) was detected and quantified using gas chromatography-mass spectrometry in single ion monitoring mode. Before the analyses of different environmental samples, the protocol was evaluated in pure culture experiments. In different environmental samples a selective labelling of fatty acids demonstrated which microbial taxa were responsible for the respective chemolithoautotrophic activity. The most strongly labelled fatty acids of a sample from a sulphide treating biofilter from an animal rendering plant were cis-7-hexadecenoic acid (16:1 cis7) and 11-methyl hexadecanoic acid (16:0 11methyl), which are as-yet not known for any sulphide-oxidizing autotroph. The fatty acid labelling pattern of an experimental biotrickling filter sample supplied with dimethyl disulphide clearly indicated the presence and activity of sulphide-oxidizing bacteria of the genus Thiobacillus. For a third environmental sample from an acid mining lake sediment, the assignment of autotrophic activity to bacteria of the genus Leptospirillum but not to Acidithiobacillus could be made by this method, as the fatty acid patterns of these bacteria show clear differences.

  13. Identification of Nitrogen-Incorporating Bacteria in Petroleum-Contaminated Arctic Soils by Using [15N]DNA-Based Stable Isotope Probing and Pyrosequencing ▿ †

    PubMed Central

    Bell, Terrence H.; Yergeau, Etienne; Martineau, Christine; Juck, David; Whyte, Lyle G.; Greer, Charles W.

    2011-01-01

    Arctic soils are increasingly susceptible to petroleum hydrocarbon contamination, as exploration and exploitation of the Arctic increase. Bioremediation in these soils is challenging due to logistical constraints and because soil temperatures only rise above 0°C for ∼2 months each year. Nitrogen is often added to contaminated soil in situ to stimulate the existing microbial community, but little is known about how the added nutrients are used by these microorganisms. Microbes vary widely in their ability to metabolize petroleum hydrocarbons, so the question becomes: which hydrocarbon-degrading microorganisms most effectively use this added nitrogen for growth? Using [15N]DNA-based stable isotope probing, we determined which taxonomic groups most readily incorporated nitrogen from the monoammonium phosphate added to contaminated and uncontaminated soil in Canadian Forces Station-Alert, Nunavut, Canada. Fractions from each sample were amplified with bacterial 16S rRNA and alkane monooxygenase B (alkB) gene-specific primers and then sequenced using lage-scale parallel-pyrosequencing. Sequence data was combined with 16S rRNA and alkB gene C quantitative PCR data to measure the presence of various phylogenetic groups in fractions at different buoyant densities. Several families of Proteobacteria and Actinobacteria that are directly involved in petroleum degradation incorporated the added nitrogen in contaminated soils, but it was the DNA of Sphingomonadaceae that was most enriched in 15N. Bacterial growth in uncontaminated soils was not stimulated by nutrient amendment. Our results suggest that nitrogen uptake efficiency differs between bacterial groups in contaminated soils. A better understanding of how groups of hydrocarbon-degraders contribute to the catabolism of petroleum will facilitate the design of more targeted bioremediation treatments. PMID:21498745

  14. Sources and fate of organic carbon and nitrogen from land to ocean: Identified by coupling stable isotopes with C/N ratio

    NASA Astrophysics Data System (ADS)

    Li, Yuan; Zhang, Haibo; Tu, Chen; Fu, Chuancheng; Xue, Yong; Luo, Yongming

    2016-11-01

    The transport of organic matter in coastal areas plays an important role in global biogeochemical cycles. The present study used stable isotopes including carbon (δ13C) and nitrogen (δ15N) and C/N ratio to assess the sources and fate of organic carbon and nitrogen in soils and sediments of a coastal plain-river plume-bay system. Changes of the δ13C and δ15N values from natural to agricultural soils in the Yellow River coastal plain reflected the contribution of C4 carbon, decomposition of organic matter and application of nitrogen fertilizer. The organic carbon in the marine sediments adjacent to the coastal plain mainly originated from C3-dominated terrestrial systems. The spatial heterogeneity of both δ13C and δ15N values indicated that Yellow River sediment transport and anthropogenic wastewater discharge were two driving forces for the sedimentary organic carbon and nitrogen dynamics in large river plume and inner bay areas. Meanwhile, the marine primary production and denitrification process as affected by excessive nutrient input also contributed to the cycling of organic matter. Wetland soils, cropland soils, vegetable soils, coastal and deep-sea sediments were the five systems controlling the cycle of organic carbon and nitrogen in the study area. A significant positive correlation between δ13C and δ15N in the Yellow River coastal plain-plume-bay region was observed, which implied the flux of organic matter from a labile pool in source regions into a more recalcitrant pool in sink regions. These findings would provide a better understanding of carbon sequestration in the coastal soil and sediment.

  15. Identification of nitrogen-incorporating bacteria in petroleum-contaminated arctic soils by using [15N]DNA-based stable isotope probing and pyrosequencing.

    PubMed

    Bell, Terrence H; Yergeau, Etienne; Martineau, Christine; Juck, David; Whyte, Lyle G; Greer, Charles W

    2011-06-01

    Arctic soils are increasingly susceptible to petroleum hydrocarbon contamination, as exploration and exploitation of the Arctic increase. Bioremediation in these soils is challenging due to logistical constraints and because soil temperatures only rise above 0°C for ∼2 months each year. Nitrogen is often added to contaminated soil in situ to stimulate the existing microbial community, but little is known about how the added nutrients are used by these microorganisms. Microbes vary widely in their ability to metabolize petroleum hydrocarbons, so the question becomes: which hydrocarbon-degrading microorganisms most effectively use this added nitrogen for growth? Using [(15)N]DNA-based stable isotope probing, we determined which taxonomic groups most readily incorporated nitrogen from the monoammonium phosphate added to contaminated and uncontaminated soil in Canadian Forces Station-Alert, Nunavut, Canada. Fractions from each sample were amplified with bacterial 16S rRNA and alkane monooxygenase B (alkB) gene-specific primers and then sequenced using large-scale parallel-pyrosequencing. Sequence data was combined with 16S rRNA and alkB gene C quantitative PCR data to measure the presence of various phylogenetic groups in fractions at different buoyant densities. Several families of Proteobacteria and Actinobacteria that are directly involved in petroleum degradation incorporated the added nitrogen in contaminated soils, but it was the DNA of Sphingomonadaceae that was most enriched in (15)N. Bacterial growth in uncontaminated soils was not stimulated by nutrient amendment. Our results suggest that nitrogen uptake efficiency differs between bacterial groups in contaminated soils. A better understanding of how groups of hydrocarbon-degraders contribute to the catabolism of petroleum will facilitate the design of more targeted bioremediation treatments.

  16. Carbon and nitrogen gain during the growth of orchid seedlings in nature.

    PubMed

    Stöckel, Marcus; Těšitelová, Tamara; Jersáková, Jana; Bidartondo, Martin I; Gebauer, Gerhard

    2014-04-01

    For germination and establishment, orchids depend on carbon (C) and nutrients supplied by mycorrhizal fungi. As adults, the majority of orchids then appear to become autotrophic. To compare the proportional C and nitrogen (N) gain from fungi in mycoheterotrophic seedlings and in adults, here we examined in the field C and N stable isotope compositions in seedlings and adults of orchids associated with ectomycorrhizal and saprotrophic fungi. Using a new highly sensitive approach, we measured the isotope compositions of seedlings and adults of four orchid species belonging to different functional groups: fully and partially mycoheterotrophic orchids associated with narrow or broad sets of ectomycorrhizal fungi, and two adult putatively autotrophic orchids associated exclusively with saprotrophic fungi. Seedlings of orchids associated with ectomycorrhizal fungi were enriched in (13) C and (15) N similarly to fully mycoheterotrophic adults. Seedlings of saprotroph-associated orchids were also enriched in (13) C and (15) N, but unexpectedly their enrichment was significantly lower, making them hardly distinguishable from their respective adult stages and neighbouring autotrophic plants. We conclude that partial mycoheterotrophy among saprotroph-associated orchids cannot be identified unequivocally based on C and N isotope compositions alone. Thus, partial mycoheterotrophy may be much more widely distributed among orchids than hitherto assumed. © 2014 The Authors. New Phytologist © 2014 New Phytologist Trust.

  17. Autotrophic denitrification in microbial fuel cells treating low ionic strength waters.

    PubMed

    Puig, Sebastià; Coma, Marta; Desloover, Joachim; Boon, Nico; Colprim, Jesús; Balaguer, M Dolors

    2012-02-21

    The presence of elevated concentrations of nitrates in drinking water has become a serious concern worldwide. The use of autotrophic denitrification in microbial fuel cells (MFCs) for waters with low ionic strengths (i.e., 1000 μS·cm(-1)) has not been considered previously. This study evaluated the feasibility of MFC technology for water denitification and also identified and quantified potential energy losses that result from their usage. The low conductivity (<1600 μS·cm(-1)) of water limited the nitrogen removal efficiency and power production of MFCs and led to the incomplete reduction of nitrate and the nitrous oxide (N(2)O) production (between 4 and 20% of nitrogen removed). Cathodic overpotential was identified as the main energy loss factors (83-90% of total losses). That high overpotential was influenced by denitrification intermediates (NO(2)(-) and N(2)O) and the potential used by microorganisms for growth, activation, and maintenance.

  18. Kinetic modelling of growth and storage molecule production in microalgae under mixotrophic and autotrophic conditions.

    PubMed

    Adesanya, Victoria O; Davey, Matthew P; Scott, Stuart A; Smith, Alison G

    2014-04-01

    In order to improve algal biofuel production on a commercial-scale, an understanding of algal growth and fuel molecule accumulation is essential. A mathematical model is presented that describes biomass growth and storage molecule (TAG lipid and starch) accumulation in the freshwater microalga Chlorella vulgaris, under mixotrophic and autotrophic conditions. Biomass growth was formulated based on the Droop model, while the storage molecule production was calculated based on the carbon balance within the algal cells incorporating carbon fixation via photosynthesis, organic carbon uptake and functional biomass growth. The model was validated with experimental growth data of C. vulgaris and was found to fit the data well. Sensitivity analysis showed that the model performance was highly sensitive to variations in parameters associated with nutrient factors, photosynthesis and light intensity. The maximum productivity and biomass concentration were achieved under mixotrophic nitrogen sufficient conditions, while the maximum storage content was obtained under mixotrophic nitrogen deficient conditions. Copyright © 2014 Elsevier Ltd. All rights reserved.

  19. Ginseng authenticity testing by measuring carbon, nitrogen, and sulfur stable isotope compositions that differ based on cultivation land and organic fertilizer type.

    PubMed

    Chung, Ill-Min; Lee, Taek-Jun; Oh, Yong-Taek; Ghimire, Bimal Kumar; Jang, In-Bae; Kim, Seung-Hyun

    2017-04-01

    The natural ratios of carbon (C), nitrogen (N), and sulfur (S) stable isotopes can be varied in some specific living organisms owing to various isotopic fractionation processes in nature. Therefore, the analysis of C, N, and S stable isotope ratios in ginseng can provide a feasible method for determining ginseng authenticity depending on the cultivation land and type of fertilizer. C, N, and S stable isotope composition in 6-yr-old ginseng roots (Jagyeongjong variety) was measured by isotope ratio mass spectrometry. The type of cultivation land and organic fertilizers affected the C, N, and S stable isotope ratio in ginseng (p < 0.05). The δ(15)NAIR and δ(34)SVCDT values in ginseng roots more significantly discriminated the cultivation land and type of organic fertilizers in ginseng cultivation than the δ(13)CVPDB value. The combination of δ(13)CVPDB, δ(15)NAIR, or δ(34)SVCDT in ginseng, except the combination δ(13)CVPDB-(34)SVCDT, showed a better discrimination depending on soil type or fertilizer type. This case study provides preliminary results about the variation of C, N, and S isotope composition in ginseng according to the cultivation soil type and organic fertilizer type. Hence, our findings are potentially applicable to evaluate ginseng authenticity depending on cultivation conditions.

  20. Novel Transcriptional Regulons for Autotrophic Cycle Genes in Crenarchaeota

    PubMed Central

    Leyn, Semen A.; Rodionova, Irina A.; Li, Xiaoqing

    2015-01-01

    ABSTRACT Autotrophic microorganisms are able to utilize carbon dioxide as their only carbon source, or, alternatively, many of them can grow heterotrophically on organics. Different variants of autotrophic pathways have been identified in various lineages of the phylum Crenarchaeota. Aerobic members of the order Sulfolobales utilize the hydroxypropionate-hydroxybutyrate cycle (HHC) to fix inorganic carbon, whereas anaerobic Thermoproteales use the dicarboxylate-hydroxybutyrate cycle (DHC). Knowledge of transcriptional regulation of autotrophic pathways in Archaea is limited. We applied a comparative genomics approach to predict novel autotrophic regulons in the Crenarchaeota. We report identification of two novel DNA motifs associated with the autotrophic pathway genes in the Sulfolobales (HHC box) and Thermoproteales (DHC box). Based on genome context evidence, the HHC box regulon was attributed to a novel transcription factor from the TrmB family named HhcR. Orthologs of HhcR are present in all Sulfolobales genomes but were not found in other lineages. A predicted HHC box regulatory motif was confirmed by in vitro binding assays with the recombinant HhcR protein from Metallosphaera yellowstonensis. For the DHC box regulon, we assigned a different potential regulator, named DhcR, which is restricted to the order Thermoproteales. DhcR in Thermoproteus neutrophilus (Tneu_0751) was previously identified as a DNA-binding protein with high affinity for the promoter regions of two autotrophic operons. The global HhcR and DhcR regulons reconstructed by comparative genomics were reconciled with available omics data in Metallosphaera and Thermoproteus spp. The identified regulons constitute two novel mechanisms for transcriptional control of autotrophic pathways in the Crenarchaeota. IMPORTANCE Little is known about transcriptional regulation of carbon dioxide fixation pathways in Archaea. We previously applied the comparative genomics approach for reconstruction of Dtx

  1. Growth rate, organic carbon and nutrient removal rates of Chlorella sorokiniana in autotrophic, heterotrophic and mixotrophic conditions.

    PubMed

    Kim, Sunjin; Park, Jeong-eun; Cho, Yong-Beom; Hwang, Sun-Jin

    2013-09-01

    This study sought to investigate the growth rate and organic carbon and nutrient removal efficiency of Chlorella sorokiniana under autotrophic, heterotrophic and mixotrophic conditions. Growth rates of the microalgae were 0.24 d(-1), 0.53 d(-1) and 0.44 d(-1) in autotrophic, heterotrophic and mixotrophic conditions, respectively. The growth rate of C. sorokiniana was significantly higher for that grown under heterotrophic conditions. The nitrogen removal rates were 13.1 mg-N/L/day, 23.9 mg-N/L/day and 19.4 mg-N/L/day, respectively. The phosphorus removal rates reached to 3.4 mg-P/L/day, 5.6 mg-P/L/day and 5.1 mg-P/L/day, respectively. Heterotrophic conditions were superior in terms of the microalgae growth and removal of nitrogen and phosphorus compared to autotrophic and mixotrophic conditions, suggesting that microalgae cultured under this condition would be most useful for application in wastewater treatment systems.

  2. Characterization and kinetics of sulfide-oxidizing autotrophic denitrification in batch reactors containing suspended and immobilized cells.

    PubMed

    Moraes, B S; Souza, T S O; Foresti, E

    2011-01-01

    Sulfide-oxidizing autotrophic denitrification is an advantageous alternative over heterotrophic denitrification, and may have potential for nitrogen removal of low-strength wastewaters, such as anaerobically pre-treated domestic sewage. This study evaluated the fundamentals and kinetics of this process in batch reactors containing suspended and immobilized cells. Batch tests were performed for different NOx-/S2- ratios and using nitrate and nitrite as electron acceptors. Autotrophic denitrification was observed for both electron acceptors, and NOx-/S2- ratios defined whether sulfide oxidation was complete or not. Kinetic parameter values obtained for nitrate were higher than for nitrite as electron acceptor. Zero-order models were better adjusted to profiles obtained for suspended cell reactors, whereas first-order models were more adequate for immobilized cell reactors. However, in the latter, mass transfer physical phenomena had a significant effect on kinetics based on biochemical reactions. Results showed that sulfide-oxidizing autotrophic denitrification can be successfully established for low-strength wastewaters and have potential for nitrogen removal from anaerobically pre-treated domestic sewage.

  3. Nitrification and growth of autotrophic nitrifying bacteria and Thaumarchaeota in the coastal North Sea

    NASA Astrophysics Data System (ADS)

    Veuger, B.; Pitcher, A.; Schouten, S.; Sinninghe Damsté, J. S.; Middelburg, J. J.

    2013-03-01

    Nitrification and the associated growth of autotrophic nitrifiers, as well as the contributions of bacteria and Thaumarchaeota to total autotrophic C-fixation by nitrifiers were investigated in the Dutch coastal North Sea from October 2007 to March 2008. Rates of nitrification were determined by incubation of water samples with 15N-ammonium and growth of autotrophic nitrifiers was measured by incubation with 13C-DIC (dissolved inorganic carbon) in the presence and absence of nitrification inhibitors (nitrapyrin and chlorate) in combination with compound-specific stable isotope (13C) analysis of bacterial and Thaumarchaeotal lipid biomarkers. Net nitrification during the sampling period was evident from the concentration dynamics of ammonium, nitrite and nitrate. Measured nitrification rates were high (41-221 nmol N L-1 h-1). Ammonium assimilation was always substantially lower than nitrification - with nitrification on average contributing 89% (range 73-97%) to total ammonium consumption. 13C-DIC fixation into bacterial and Thaumarchaeotal lipids was strongly reduced by the nitrification inhibitors (27-95 %). The inhibitor-sensitive 13C-PLFA (phospholipid-derived fatty acid) pool was dominated by the common PLFAs 16:0, 16:1ω7c and 18:1ω7c throughout the whole sampling period and occasionally also included the polyunsaturated fatty acids 18:2ω6c and 18:3ω3. 13C-DIC fixation activity of the nitrifying bacteria was much higher than that of the nitrifying Thaumarchaeota throughout the whole sampling period, even during the peak in Thaumarchaeotal abundance and activity. This suggests that the contribution of autotrophic Thaumarchaeota to nitrification during winter in the coastal North Sea may have been smaller than expected from their gene abundance (16S rRNA and amoA (ammonia monooxygenase)). These results emphasize the importance of direct measurements of the actual activity of bacteria and Thaumarchaeota, rather than abundance measurements only, in order to

  4. Nitrification and growth of autotrophic nitrifying bacteria and Thaumarchaeota in the coastal North Sea

    NASA Astrophysics Data System (ADS)

    Veuger, B.; Pitcher, A.; Schouten, S.; Sinninghe Damsté, J. S.; Middelburg, J. J.

    2012-11-01

    Nitrification and the associated growth of autotrophic nitrifiers, as well as the contributions of bacteria and Thaumarchaeota to total autotrophic C-fixation by nitrifiers were investigated in the Dutch coastal North Sea from October 2007 to March 2008. Rates of nitrification were determined by incubation of water samples with 15N-ammonium and growth of autotrophic nitrifiers was measured by incubation with 13C-DIC in the presence and absence of nitrification inhibitors (nitrapyrin and chlorate) in combination with compound-specific stable isotope (13C) analysis of bacterial- and Thaumarchaeotal lipid biomarkers. Net nitrification during the sampling period was evident from the concentration dynamics of ammonium, nitrite and nitrate. Measured nitrification rates were high (41-221 nmol N l-1h-1). Ammonium assimilation was always substantially lower than nitrification with nitrification on average contributing 89% (range 73-97%) to total ammonium consumption. 13C-DIC fixation into bacterial and Thaumarchaeotal lipids was strongly reduced by the nitrification inhibitors (27-95%). The inhibitor-sensitive 13C-PLFA pool was dominated by the common PLFAs 16:0, 16:1ω7c and 18:1ω7c throughout the whole sampling period and occasionally also included the polyunsaturated fatty acids 18:2ω6c and 18:3ω3. Cell-specific 13C-DIC fixation activity of the nitrifying bacteria was much higher than that of the nitrifying Thaumarchaeota throughout the whole sampling period, even during the peak in Thaumarchaeotal abundance and activity. This suggests that the contribution of autotrophic Thaumarchaeota to nitrification during winter in the coastal North Sea may have been smaller than expected from their gene abundance. These results emphasize the importance of direct measurements of the actual activity of bacteria and Thaumarchaeota, rather than abundance measurements only, in order to elucidate their biogeochemical importance. The ratio between rates of nitrification versus DIC

  5. Impact of diazotrophy on N stable isotope signatures of nitrate and particulate organic nitrogen: case studies in the north-eastern tropical Atlantic Ocean.

    PubMed

    Wannicke, Nicola; Liskow, Iris; Voss, Maren

    2010-09-01

    During two independent cruises in the north-eastern tropical Atlantic Ocean, we applied two different approaches to investigate the impact of diazotrophy on nitrogen stable isotope signatures in nitrate and particulate organic nitrogen (PON) of the food-web constituents. The first approach, used during the Poseidon cruise 348 in the Mauritanian upwelling, investigated the long-term influence of diazotrophy on the natural abundance of δ(15)N-NO(-)(3) and PON. The second approach, adopted during the Cape Verde field cruise, applied stable isotope tracer addition experiments. These served to determine the instantaneous transfer of diazotrophic N to the higher trophic level. Both approaches showed that N(2) fixation was compatible with the pattern and the magnitude of the isotopic depletion of dissolved NO(-)(3) during the Mauritanian upwelling cruise, as well as PON in zooplankton and phytoplankton during the Cape Verde cruises. An N-budget using (15)N incorporation rates and diazotrophic N(2) fixation rates showed that 6 % of the daily N(2) fixation was potentially taken up by the mesozooplankton community. Direct grazing accounted for 56 % of gross mesozooplanktonic N incorporation, while 46 % occurred due to channelling through the microbial loop.

  6. Carbon and nitrogen stable isotopes of well-preserved Middle Pleistocene bone collagen from Schöningen (Germany) and their paleoecological implications.

    PubMed

    Kuitems, Margot; van der Plicht, Johannes; Drucker, Dorothée G; Van Kolfschoten, Thijs; Palstra, Sanne W L; Bocherens, Hervé

    2015-12-01

    Carbon and nitrogen stable isotopes in bone collagen can provide valuable information about the diet and habitat of mammal species. However, bone collagen degrades in normal circumstances very rapidly, and isotope analyses are therefore usually restricted to fossil material with a Late Pleistocene or Holocene age. The Middle Pleistocene site of Schöningen, dated to around 300,000 years ago, yielded bones and teeth with an exceptionally good state of collagen preservation. This allowed us to measure reliable biogenic carbon and nitrogen stable isotope ratios for different herbivorous taxa from the families Elephantidae, Rhinocerotidae, Equidae, Cervidae, and Bovidae. The results provide insights regarding the paleoenvironmental setting in which Middle Pleistocene hominins operated. The vegetation consumed by the herbivores from the famous spear horizon originates from open environments. During the climatic Reinsdorf Interglacial optimum, the landscape seems to have been relatively open as well, but certainly included parts that were forested. The results also indicate some niche partitioning; different herbivore species used different plant resources. For instance, the horses seem to have been predominantly browsers, while the straight-tusked elephants were feeding chiefly on grass. Copyright © 2015 Elsevier Ltd. All rights reserved.

  7. Use of the Stable Nitrogen Isotope to Reveal the Source-Sink Regulation of Nitrogen Uptake and Remobilization during Grain Filling Phase in Maize

    PubMed Central

    Yang, Lan; Guo, Song; Chen, Qinwu; Chen, Fanjun; Yuan, Lixing; Mi, Guohua

    2016-01-01

    Although the remobilization of vegetative nitrogen (N) and post-silking N both contribute to grain N in maize (Zea mays L.), their regulation by grain sink strength is poorly understood. Here we use 15N labeling to analyze the dynamic behaviors of both pre- and post-silking N in relation to source and sink manipulation in maize plants. The results showed that the remobilization of pre-silking N started immediately after silking and the remobilized pre-silking N had a greater contribution to grain N during early grain filling, with post-silking N importance increasing during the later filling stage. The amount of post-silking N uptake was largely driven by post-silking dry matter accumulation in both grain as well as vegetative organs. Prevention of pollination during silking had less effect on post-silking N uptake, as a consequence of compensatory growth of stems, husk + cob and roots. Also, leaves continuously export N even though grain sink was removed. The remobilization efficiency of N in the leaf and stem increased with increasing grain yield (hence N requirement). It is suggested that the remobilization of N in the leaf is controlled by sink strength but not the leaf per se. Enhancing post-silking N uptake rather than N remobilization is more likely to increase grain N accumulation. PMID:27606628

  8. A neutron diffraction study of oxygen and nitrogen ordering in a kinetically stable orthorhombic iron doped titanium oxynitride

    SciTech Connect

    Wu, On Ying; Parkin, Ivan P; Hyett, Geoffrey

    2012-06-15

    The synthesis of a polycrystalline powder sample of iron doped orthorhombic titanium oxynitride, Ti{sub 2.92}Fe{sub 0.01}O{sub 4.02}N{sub 0.98}, on the scale of 0.7 g has been achieved. This was conducted by the unusual route of delamination from a steel substrate of a thin film deposited using atmospheric pressure chemical vapour deposition. The structure of the titanium oxynitride is presented, determined from a combined analysis of X-ray and neutron powder diffraction data. The use of neutron diffraction allows the position of the oxygen and nitrogen ions in the material to be reported unambiguously for the first time. In this study Ti{sub 2.92}Fe{sub 0.01}O{sub 4.02}N{sub 0.98} is found to crystallise in the Cmcm space group, iso-structural pseudobrookite, with lattice parameters a=3.81080(6) A, b=9.6253(2) A, and c=9.8859(2) A, and contains partial oxygen-nitrogen ordering. Of the three anion sites in this structure one is exclusively occupied by oxygen, while the remaining two sites are occupied by oxygen and nitrogen in a disordered manner. Testing indicates that this iron doped titanium oxynitride is a metastable phase that decomposes above 700 Degree-Sign C into TiN and TiO{sub 2}, the thermodynamic products. - Graphical abstract: We report the synthesis of Ti{sub 2.92}Fe{sub 0.01}O{sub 4.02}N{sub 0.98} deposited as a thin film using atmospheric pressure chemical vapour deposition onto stainless steel, which is then delaminated to produce a polycrystalline powder sample. This powder sample was used in a neutron diffraction experiment, and analysis of this data has allowed the position of the oxygen and nitrogen ions in the material to be reported unambiguously for the first time. Ti{sub 2.92}Fe{sub 0.01}O{sub 4.02}N{sub 0.98} is found to crystallise in the Cmcm space group iso-structural pseudobrookite and contains partial oxygen-nitrogen ordering. Highlights: Black-Right-Pointing-Pointer Partial oxygen and nitrogen ordering has been observed using neutron

  9. Stable carbon and nitrogen isotopic compositions of ambient aerosols collected from Okinawa Island in the western North Pacific Rim, an outflow region of Asian dusts and pollutants

    NASA Astrophysics Data System (ADS)

    Kunwar, Bhagawati; Kawamura, Kimitaka; Zhu, Chunmao

    2016-04-01

    Stable carbon (δ13C) and nitrogen (δ15N) isotope ratios were measured for total carbon (TC) and nitrogen (TN), respectively, in aerosol (TSP) samples collected at Cape Hedo, Okinawa, an outflow region of Asian pollutants, during 2009-2010. The averaged δ13C and δ15N ratios are -22.2‰ and +12.5‰, respectively. The δ13C values are similar in both spring (-22.5‰) and winter (-22.5‰), suggesting the similar sources and/or source regions. We found that δ13C from Okinawa aerosols are ca. 2‰ higher than those reported from Chinese megacities probably due to photochemical aging of organic aerosols. A strong correlation (r = 0.81) was found between nss-Ca and TSP, suggesting that springtime aerosols are influenced from Asian dusts. However, carbonates in the Asian dusts were titrated with acidic species such as sulfuric acid and oxalic acid during atmospheric transport although two samples suggested the presence of remaining carbonate. No correlations were found between δ13C and tracer compounds (levoglucosan, elemental carbon, oxalic acid, and Na+). During winter and spring, coal burning is significant source in China. Based on isotopic mass balance, contribution of coal burning origin particles to total aerosol carbon was estimated as ca. 97% in winter, which is probably associated with the high emissions in China. Contribution of NO3- to TN was on average 45% whereas that of NH4+ was 18%. These results suggest that vehicular exhaust is an important source of TN in Okinawa aerosols. Concentration of water-soluble organic nitrogen (WSON) is higher in summer, suggesting that WSON is more emitted from the ocean in warmer season whereas inorganic nitrogen is more emitted in winter and spring from pollution sources in the Asian continent.

  10. The feasibility study of autotrophic denitrification with iron sludge produced for sulfide control.

    PubMed

    Wei, Yangyang; Dai, Ji; Mackey, Hamish R; Chen, Guang-Hao

    2017-10-01

    Ferric iron is widely dosed in wastewater treatment plants dealing with sulfide for septicity control, which generates a great amount of iron-rich chemical sludge that is challenging and costly to dispose. This study investigates the feasibility of using this iron sludge as the electron donor for autotrophic denitrification, not only realizing high nitrogen removal efficiency without additional carbon source requirement, but also partially mitigating iron-rich chemical sludge disposal and reduce sludge production by enriching low-yield autotrophic denitrifiers in the system. Both batch tests and performance monitoring of a lab-scale up-flow anaerobic sludge blanket reactor with a more than 300 days of operation were conducted. All the results confirmed the feasibility of using iron sludge as electron donor for autotrophic denitrification. The nitrate reduction rate with iron sludge was highly influenced by the type of ferrous electron donor and the electron donor/acceptor ratio. Ferrous hydroxide had significantly higher nitrate reduction rate than ferrous sulfide at the same electron donor/acceptor ratio. The nitrate reduction rate also accelerated with the increase of the electron donor/acceptor ratio. However, if the total surface area of the iron sludge is considered for comparison, it was shown that ferrous hydroxide and ferrous sulfide provided similar nitrate reduction rates of around 0.02 mmol N/m(2)/d in this study, indicating total surface area would be the key parameter for denitrification efficiency for the solid phase electron donor. Copyright © 2017 Elsevier Ltd. All rights reserved.

  11. Autotrophic Ammonia Oxidation at Low pH through Urea Hydrolysis

    PubMed Central

    Burton, Simon A. Q.; Prosser, Jim I.

    2001-01-01

    Ammonia oxidation in laboratory liquid batch cultures of autotrophic ammonia oxidizers rarely occurs at pH values less than 7, due to ionization of ammonia and the requirement for ammonium transport rather than diffusion of ammonia. Nevertheless, there is strong evidence for autotrophic nitrification in acid soils, which may be carried out by ammonia oxidizers capable of using urea as a source of ammonia. To determine the mechanism of urea-linked ammonia oxidation, a ureolytic autotrophic ammonia oxidizer, Nitrosospira sp. strain NPAV, was grown in liquid batch culture at a range of pH values with either ammonium or urea as the sole nitrogen source. Growth and nitrite production from ammonium did not occur at pH values below 7. Growth on urea occurred at pH values in the range 4 to 7.5 but ceased when urea hydrolysis was complete, even though ammonia, released during urea hydrolysis, remained in the medium. The results support a mechanism whereby urea enters the cells by diffusion and intracellular urea hydrolysis and ammonia oxidation occur independently of extracellular pH in the range 4 to 7.5. A proportion of the ammonia produced during this process diffuses from the cell and is not subsequently available for growth if the extracellular pH is less than 7. Ureolysis therefore provides a mechanism for nitrification in acid soils, but a proportion of the ammonium produced is likely to be released from the cell and may be used by other soil organisms. PMID:11425707

  12. Ammonium Removal by the Oxygen-Limited Autotrophic Nitrification-Denitrification System

    PubMed Central

    Kuai, Linping; Verstraete, Willy

    1998-01-01

    The present lab-scale research reveals the potential of implementation of an oxygen-limited autotrophic nitrification-denitrification (OLAND) system with normal nitrifying sludge as the biocatalyst for the removal of nitrogen from nitrogen-rich wastewater in one step. In a sequential batch reactor, synthetic wastewater containing 1 g of NH4+-N liter−1 and minerals was treated. Oxygen supply to the reactor was double-controlled with a pH controller and a timer. At a volumetric loading rate (Bv) of 0.13 g of NH4+-N liter−1 day−1, about 22% of the fed NH4+-N was converted to NO2−-N or NO3−-N, 38% remained as NH4+-N, and the other 40% was removed mainly as N2. The specific removal rate of nitrogen was on the order of 50 mg of N liter−1 day−1, corresponding to 16 mg of N g of volatile suspended solids−1 day−1. The microorganisms which catalyzed the OLAND process are assumed to be normal nitrifiers dominated by ammonium oxidizers. The loss of nitrogen in the OLAND system is presumed to occur via the oxidation of NH4+ to N2 with NO2− as the electron acceptor. Hydroxylamine stimulated the removal of NH4+ and NO2−. Hydroxylamine oxidoreductase (HAO) or an HAO-related enzyme might be responsible for the loss of nitrogen. PMID:9797314

  13. Amino Acid Specific Stable Nitrogen Isotope Values in Avian Tissues: Insights from Captive American Kestrels and Wild Herring Gulls.

    PubMed

    Hebert, C E; Popp, B N; Fernie, K J; Ka'apu-Lyons, C; Rattner, B A; Wallsgrove, N

    2016-12-06

    Through laboratory and field studies, the utility of amino acid compound-specific nitrogen isotope analysis (AA-CSIA) in avian studies is investigated. Captive American kestrels (Falco sparverius) were fed an isotopically characterized diet and patterns in δ(15)N values of amino acids (AAs) were compared to those in their tissues (muscle and red blood cells) and food. Based upon nitrogen isotope discrimination between diet and kestrel tissues, AAs could mostly be categorized as source AAs (retaining baseline δ(15)N values) and trophic AAs (showing (15)N enrichment). Trophic discrimination factors based upon the source (phenylalanine, Phe) and trophic (glutamic acid, Glu) AAs were 4.1 (muscle) and 5.4 (red blood cells), lower than those reported for metazoan invertebrates. In a field study involving omnivorous herring gulls (Larus argentatus smithsonianus), egg AA isotopic patterns largely retained those observed in the laying female's tissues (muscle, red blood cells, and liver). Realistic estimates of gull trophic position were obtained using bird Glu and Phe δ(15)N values combined with β values (difference in Glu and Phe δ(15)N in primary producers) for aquatic and terrestrial food webs. Egg fatty acids were used to weight β values for proportions of aquatic and terrestrial food in gull diets. This novel approach can be applied to generalist species that feed across ecosystem boundaries.

  14. Amino acid specific stable nitrogen isotope values in avian tissues: Insights from captive American kestrels and wild herring gulls

    USGS Publications Warehouse

    Hebert, Craig E.; Popp, B.N.; Fernie, K.J.; Ka'apu-Lyons, C.; Rattner, Barnett A.; Wallsgrove, N.

    2016-01-01

    Through laboratory and field studies, the utility of amino acid compound-specific nitrogen isotope analysis (AA-CSIA) in avian studies is investigated. Captive American kestrels (Falco sparverius) were fed an isotopically characterized diet and patterns in δ15N values of amino acids (AAs) were compared to those in their tissues (muscle and red blood cells) and food. Based upon nitrogen isotope discrimination between diet and kestrel tissues, AAs could mostly be categorized as source AAs (retaining baseline δ15N values) and trophic AAs (showing 15N enrichment). Trophic discrimination factors based upon the source (phenylalanine, Phe) and trophic (glutamic acid, Glu) AAs were 4.1 (muscle) and 5.4 (red blood cells), lower than those reported for metazoan invertebrates. In a field study involving omnivorous herring gulls (Larus argentatus smithsonianus), egg AA isotopic patterns largely retained those observed in the laying female’s tissues (muscle, red blood cells, and liver). Realistic estimates of gull trophic position were obtained using bird Glu and Phe δ15N values combined with β values (difference in Glu and Phe δ15N in primary producers) for aquatic and terrestrial food webs. Egg fatty acids were used to weight β values for proportions of aquatic and terrestrial food in gull diets. This novel approach can be applied to generalist species that feed across ecosystem boundaries.

  15. Autotrophic acetyl coenzyme A biosynthesis in Methanococcus maripaludis.

    PubMed Central

    Shieh, J; Whitman, W B

    1988-01-01

    To detect autotrophic CO2 assimilation in cell extracts of Methanococcus maripaludis, lactate dehydrogenase and NADH were added to convert pyruvate formed from autotrophically synthesized acetyl coenzyme A to lactate. The lactate produced was determined spectrophotometrically. When CO2 fixation was pulled in the direction of lactate synthesis, CO2 reduction to methane was inhibited. Bromoethanesulfonate (BES), a potent inhibitor of methanogenesis, enhanced lactate synthesis, and methyl coenzyme M inhibited it in the absence of BES. Lactate synthesis was dependent on CO2 and H2, but H2 + CO2-independent synthesis was also observed. In cell extracts, the rate of lactate synthesis was about 1.2 nmol min-1 mg of protein-1. When BES was added, the rate of lactate synthesis increased to 2.3 nmol min-1 mg of protein-1. Because acetyl coenzyme A did not stimulate lactate synthesis, pyruvate synthase may have been the limiting activity in these assays. Radiolabel from 14CO2 was incorporated into lactate. The percentages of radiolabel in the C-1, C-2, and C-3 positions of lactate were 73, 33, and 11%, respectively. Both carbon monoxide and formaldehyde stimulated lactate synthesis. 14CH2O was specifically incorporated into the C-3 of lactate, and 14CO was incorporated into the C-1 and C-2 positions. Low concentrations of cyanide also inhibited autotrophic growth, CO dehydrogenase activity, and autotrophic lactate synthesis. These observations are in agreement with the acetogenic pathway of autotrophic CO2 assimilation. PMID:3133359

  16. The influence of trophic level and feeding location of the levels of organochlorine contaminants in seabird eggs as revealed by stable carbon and nitrogen isotope analysis

    SciTech Connect

    Hobson, K.; Jarman, W.M.; Bott, J.A.; Bacon, C.E.; Sydeman, W.

    1994-12-31

    Seabird eggs have been used extensively to assay contaminants in marine food webs, but links to trophic level or feeding location have remained poorly understood due to limitations inherent in conventional dietary studies. Stable-isotope analysis of bird eggs may be used to infer trophic position and feeding location of adult seabirds and can be readily correlated with measurements of egg contaminant levels. The authors measured stable-carbon ({delta}{sup 13}C) and nitrogen ({delta}{sup 15}N) isotope abundance, and organochlorine contaminants (DDTs, PCBs, chlordanes, etc.) in eggs from Cassin`s Auklet (Ptychoramphus aleutica), Common Murre (Uria aalge), Pigeon Guillemot (Cepphus columba). Rhinoceros Auklet (Cerorhinca monocerata), Pelagic Cormorant (Phalacrocorax pelagicus), Brandt`s Cormorant (Phalacrocorax penicillatus), and Western Gull (Larus) from Southeast Farallon Island together with rockfish (Sebastes spp.), anchovy (Engraulis spp.), and euphausiid prey from the Gulf of the Farallones. Consistent with its planktivorous diet and pelagic feeding habits, Cassin`s Auklet showed the lowest mean {delta}{sup 15}N value and the least enriched {delta}{sup 13}C values. Measures of trophic level and foraging location were constructed for all other seabirds relative to these isotopic endpoints. Contaminant levels in the eggs and fish will be interpreted in light of the stable-isotope results.

  17. Local Alterations to the Nitrogen Cycle as Indicated by Tree Ring and Foliage Stable Isotopes, Xi'an China

    NASA Astrophysics Data System (ADS)

    Michelsen-Correa, S.; Qian, H.

    2015-12-01

    China is currently experiencing some of the worst pollution problems on Earth. The increase in nitrogen deposition from industrial pollution sources over the past 30 years, has been substantial enough to increase foliar N uptake in plants growing in unfertilized fields and forests throughout China. The δ15N signature of foliage and soil have been used to infer changes in the biogeochemical cycling of N in the surrounding ecosystem. The current understanding of global trends in foliar δ15N however, is limited for the East Asia and Pacific region. Most of the research to date has been conducted in temperate and boreal forests of North America and Europe. In this study, two forested sites were sampled on the Loess Plateau, approximately 80km east of the city of Xi'an, Shaanxi Province, China. The study sites are 1 and 4km down wind of an industrial center including a large nitrogen fertilizer plant. Ecosystem components sampled include soil, forest floor, bole wood, and foliage. We use a combination of δ15N and δ13C of the tree rings, foliage, and soil as indicators of a changing nitrogen cycle and the physiological response of Chinese parasol trees (Firmiana simplex) over time. CN ratios at the study sites suggest that both forested stands are saturated with respect to N. A positive correlation between soil N and foliar δ15N is attributed to the leaching of N depleted in 15N with increasing N availability. Despite this positive correlation within the study area, overall foliar δ15N with a mean of -8.2‰ is low relative to foliage sampled in regions with lower atmospheric N inputs. Foliage and bole wood samples closest to the industrial center have higher δ13C, which is consistent with greater exposure to NOx emissions. While difference in δ15N of ecosystem components between sites is consistent with global trends, the absolute values for the whole study area are relatively low and attributed to N inputs from industrial sources depleted in 15N.

  18. Stable and null current hysteresis perovskite solar cells based nitrogen doped graphene oxide nanoribbons hole transport layer

    PubMed Central

    Kim, Jeongmo; Mat Teridi, Mohd Asri; Mohd Yusoff, Abd. Rashid bin; Jang, Jin

    2016-01-01

    Perovskite solar cells are becoming one of the leading technologies to reduce our dependency on traditional power sources. However, the frequently used component poly(3,4-ethylenedioxythiophene) polystyrene sulfonate (PEDOT:PSS) has several shortcomings, such as an easily corroded indium-tin-oxide (ITO) interface at elevated temperatures and induced electrical inhomogeneity. Herein, we propose solution-processed nitrogen-doped graphene oxide nanoribbons (NGONRs) as a hole transport layer (HTL) in perovskite solar cells, replacing the conducting polymer PEDOT:PSS. The conversion efficiency of NGONR-based perovskite solar cells has outperformed a control device constructed using PEDOT:PSS. Moreover, our proposed NGONR-based devices also demonstrate a negligible current hysteresis along with improved stability. This work provides an effective route for substituting PEDOT:PSS as the effective HTL. PMID:27277388

  19. Stable and null current hysteresis perovskite solar cells based nitrogen doped graphene oxide nanoribbons hole transport layer.

    PubMed

    Kim, Jeongmo; Mat Teridi, Mohd Asri; Mohd Yusoff, Abd Rashid Bin; Jang, Jin

    2016-06-09

    Perovskite solar cells are becoming one of the leading technologies to reduce our dependency on traditional power sources. However, the frequently used component poly(3,4-ethylenedioxythiophene) polystyrene sulfonate ( PSS) has several shortcomings, such as an easily corroded indium-tin-oxide (ITO) interface at elevated temperatures and induced electrical inhomogeneity. Herein, we propose solution-processed nitrogen-doped graphene oxide nanoribbons (NGONRs) as a hole transport layer (HTL) in perovskite solar cells, replacing the conducting polymer PSS. The conversion efficiency of NGONR-based perovskite solar cells has outperformed a control device constructed using PSS. Moreover, our proposed NGONR-based devices also demonstrate a negligible current hysteresis along with improved stability. This work provides an effective route for substituting PSS as the effective HTL.

  20. Stable and null current hysteresis perovskite solar cells based nitrogen doped graphene oxide nanoribbons hole transport layer

    NASA Astrophysics Data System (ADS)

    Kim, Jeongmo; Mat Teridi, Mohd Asri; Mohd Yusoff, Abd. Rashid Bin; Jang, Jin

    2016-06-01

    Perovskite solar cells are becoming one of the leading technologies to reduce our dependency on traditional power sources. However, the frequently used component poly(3,4-ethylenedioxythiophene) polystyrene sulfonate (PEDOT:PSS) has several shortcomings, such as an easily corroded indium-tin-oxide (ITO) interface at elevated temperatures and induced electrical inhomogeneity. Herein, we propose solution-processed nitrogen-doped graphene oxide nanoribbons (NGONRs) as a hole transport layer (HTL) in perovskite solar cells, replacing the conducting polymer PEDOT:PSS. The conversion efficiency of NGONR-based perovskite solar cells has outperformed a control device constructed using PEDOT:PSS. Moreover, our proposed NGONR-based devices also demonstrate a negligible current hysteresis along with improved stability. This work provides an effective route for substituting PEDOT:PSS as the effective HTL.

  1. High CO2 subsurface environment enriches for novel microbial lineages capable of autotrophic carbon fixation

    NASA Astrophysics Data System (ADS)

    Probst, A. J.; Jerett, J.; Castelle, C. J.; Thomas, B. C.; Sharon, I.; Brown, C. T.; Anantharaman, K.; Emerson, J. B.; Hernsdorf, A. W.; Amano, Y.; Suzuki, Y.; Tringe, S. G.; Woyke, T.; Banfield, J. F.

    2015-12-01

    Subsurface environments span the planet but remain little understood from the perspective of the capacity of the resident organisms to fix CO2. Here we investigated the autotrophic capacity of microbial communities in range of a high-CO2 subsurface environments via analysis of 250 near-complete microbial genomes (151 of them from distinct species) that represent the most abundant organisms over a subsurface depth transect. More than one third of the genomes belonged to the so-called candidate phyla radiation (CPR), which have limited metabolic capabilities. Approximately 30% of the community members are autotrophs that comprise 70% of the microbiome with metabolism likely supported by sulfur and nitrogen respiration. Of the carbon fixation pathways, the Calvin Benson Basham Cycle was most common, but the Wood-Ljungdhal pathway was present in the greatest phylogenetic diversity of organisms. Unexpectedly, one organism from a novel phylum sibling to the CPR is predicted to fix carbon by the reverse TCA cycle. The genome of the most abundant organism, an archaeon designated "Candidatus Altiarchaeum hamiconexum", was also found in subsurface samples from other continents including Europe and Asia. The archaeon was proven to be a carbon fixer using a novel reductive acetyl-CoA pathway. These results provide evidence that carbon dioxide is the major carbon source in these environments and suggest that autotrophy in the subsurface represents a substantial carbon dioxide sink affecting the global carbon cycle.

  2. Selenium and stable isotopes of carbon and nitrogen in the benthic clam Corbula amurensis from Northern San Francisco Bay, California: May 1995-February 2010

    USGS Publications Warehouse

    Kleckner, Amy E.; Stewart, A. Robin; Luoma, Samuel N.

    2010-01-01

    The clam-based food webs of San Francisco Bay, California efficiently bioaccumlate selenium and thus provide pathways for exposure to predators important to the estuary. This study documents changes in monthly selenium concentrations for the clam Corbula amurensis, a keystone species of the estuary, at five locations in northern San Francisco Bay from 1995 through 2010. Samples were collected from designated U.S. Geological Survey stations and prepared and analyzed by U.S. Geological Survey methods. Stable isotopes of carbon and nitrogen in soft tissues of clams also were measured as an indicator of sources of selenium for the clams. These monitoring data indicate that clam selenium concentrations ranged from a low of 2 to a high of 22 micrograms per gram dry weight with strong spatial and seasonal variation over the period of study.

  3. Microalgae as part of the autotrophic component of life support systems for future planetary bases

    NASA Astrophysics Data System (ADS)

    Sychev, Vladimir; Levinskikh, Margarita

    and the algal-bacterial community will act as a backup. Nonetheless, microalgae will still be functioning within the autotrophic component though their proportion will depend on the amount of nitrogen compounds subjected to utilization in the system.

  4. Photosynthesis in Rhodospirillum rubrum. I. Autotrophic Carbon Dioxide Fixation 1

    PubMed Central

    Anderson, Louise; Fuller, R. C.

    1967-01-01

    The incorporation and distribution of activity from 14CO2 was investigated under autotrophic conditions in the facultative photoautotroph, Rhodospirillum rubrum, with cells cultured on hydrogen, carbon dioxide, and ammonium sulfate. In 1 second 14CO2 fixation experiments essentially all of the activity was found in 3-phosphoglyceric acid: plotted against time percent incorporation into phosphate esters has a strikingly negative slope. These results suggest that under autotrophic conditions the reductive pentose phosphate cycle or the key reactions of the cycle play a major role in carbon metabolism in this photosynthetic bacterium. Incorporation into amino acids and into intermediates of the tricarboxylic acid cycle was quite low. PMID:6042357

  5. Biosynthesis of Cytokinins in Cytokinin-Autotrophic Tobacco Callus

    PubMed Central

    Einset, John W.; Skoog, Folke

    1973-01-01

    A cytokinin-autotrophic strain of tobacco callus contained cytokinin-active compounds with chromatographic mobilities on Sephadex LH-20 corresponding to ribosylzeatin, zeatin, and 6-Δ2-isopentenylaminopurine. Zeatin, the apparent major cytokinin, was estimated to be present at a concentration of 10-4 μmol/kg of tissue. Cytokinin-autotrophic callus supplied with [14C]adenine produced radioactive components with the same chromatographic properties as zeatin and 6-Δ2-isopentenylaminopurine. These components were not obtained from cytokinin-dependent tissue supplied with [14C]adenine in the same manner. PMID:16592068

  6. Relationship of polychlorinated dibenzo-p-dioxin and polychlorinated dibenzofuran levels to stable-nitrogen isotope abundance in marine birds and mammals in coastal California

    SciTech Connect

    Jarman, W.M.; Sydeman, W.J.; Hobson, K.A.; Bergqvist, P.A.

    1997-05-01

    Levels of polychlorinated dibenzo-p-dioxins (PCDDs) and polychlorinated dibenzofurans (PCDFs) were determined in common murre (Uria aalge), Brandt`s cormorant (Phalacrocorax penicillatus), rhinoceros auklet (Cerorhinca monocerata), and pigeon guillemot (Cepphus columba) eggs, and Steller sea lion (Eumetopias jubatus) blubber collected from the Gulf of the Farallones National Marine Sanctuary in 1993. In addition, the samples were analyzed for stable-nitrogen isotopes ({delta}{sup 15}N). Of the PCDDs and PCDFs, the 2,3,7,8-TCDD (TCDD) and 2,3,7,8-TCDF (TCDF) congeners were the most prominent in the birds. The levels of TCDD in the eggs ranged from 0.2 to 6.6 ng/wet kg in the pigeon guillemot and Brandt`s cormorant, respectively. The TCDF ranged from 0.30 to 2.25 ng/kg in the pigeon guillemot and Brandt`s cormorant eggs, respectively. Other prominent PCDD and PCDF congeners detected in all bird species were 1,2,3,6,7,8-HxCDD, 2,3,4,7,8-PeCDF, 1,2,3,7,8-PeCDD and 1,2,3,4,6,7,8-HpCDD. In the Steller sea lion the most prominent congeners were 1,2,3,7,8-PeCDD at 3.2 ng/kg, 2,3,7,8-TCDD at 2.9 ng/kg, OCDF at 2.2 ng/kg, 1,2,3,6,7,8-HxCDD at 1.92 ng/kg, and 1,2,3,4,7,8-HxCDF at 1.3 ng/kg. Stable-nitrogen values ranged from 16.9% in the pigeon guillemot and rhinoceros auklet to 19.8% in the Steller sea lion.

  7. Stable nitrogen isotopes in the turtle grass Thalassia testudinum from the Mexican Caribbean: Implications of anthropogenic development

    NASA Astrophysics Data System (ADS)

    Sánchez, Alberto; Ortiz-Hernández, Ma. Concepción; Talavera-Sáenz, Ana; Aguíñiga-García, Sergio

    2013-12-01

    Nutrient inputs associated with population growth threaten the integrity of coastal ecosystems. To assess the rapid increase in tourism, we compared the δ15N from Thalassia testudinum collected at sites with different levels of tourism development to detect the N inputs of wastewater discharge (WD) along the coast of Quintana Roo. The contributions of nitrogen enriched in 15N are directly related to the increase of WD inputs in areas of tourism development (Nichupte Lagoon in Cancun) and decreased toward Bahia Akumal and Tulum. The δ15N from T. testudinum was significantly lower at Mahahual and Puerto Morelos. In areas of the lowest development and with tourist activity restricted, such as the Yum Balam Reserve and Sian Ka'an Biosphere Reserve, the δ15N values were relatively enriched compared to Mahahual and Puerto Morelos. Therefore, Puerto Morelos and Mahahual may be used for baseline isotopic monitoring where tourist activities are growing and can lead to environmental pressure on the reef lagoon ecosystem. The anthropogenic N input has the potential to impact, both environmentally and economically, the seagrass meadows and the coral reefs along the coast of Quintana Roo and the Caribbean.

  8. Foliar stable carbon and nitrogen isotopes in woody Mediterranean species with different life form and post-fire regeneration.

    PubMed

    Saura-Mas, S; Lloret, F

    2010-01-01

    Wildfire is an important ecological disturbance factor in most Mediterranean ecosystems. In the Mediterranean Basin, most shrub species can regenerate after fire by resprouting or seeding. Here, we hypothesize that post-fire regenerative syndromes may potentially co-vary with traits directly related to functional properties involved in resource use. Thus, seeders with a shorter life span and smaller size would have lower water-use efficiency (WUE) than re-sprouting species and would take up nutrients such as nitrogen from more superficial parts of the soil. To test this hypothesis, we compared leaf (13)C and (15)N signatures from 29 co-existing species with different post-fire regeneration strategies. We also considered life form as an additional explanatory variable of the differences between post-fire regenerative groups. Our data support the hypothesis that seeder species (which mostly evolved in the Quaternary under a Mediterranean climate) have lower WUE and less stomatal control than non-seeders (many of which evolved under different climatic conditions in the Tertiary) and consequently greater consumption of water per unit biomass. This would be related to their smaller life forms, which tend to have lower WUE and shorter life and leaf lifespan. Differences in (15)N also support the hypothesis that resprouters have deeper root systems than non-resprouters. The study supports the hypothesis of an overlap between plant functional traits and plant attributes describing post-disturbance resilience.

  9. A critical review of the use stable N-isotopes to assess nitrogen elimination in the global ocean

    NASA Astrophysics Data System (ADS)

    Lehmann, M. F.

    2012-12-01

    The mean nitrogen (N) isotopic composition of oceanic nitrate is set by the balance of the main N sinks and inputs to the ocean, and can thus be used to constrain global N fluxes. The δ15N of organic matter preserved in marine sediments provides insight into past changes of N-inventory altering processes such as denitrification and N2 fixation. The use of δ15N as tracer of sedimentary versus water-column nitrate reduction, today and in the past, requires the knowledge of the N isotope effects of these processes on the ocean nitrate pool. Estimates on the partitioning between the two fixed N elimination processes are particularly sensitive to the N isotope effect of benthic denitrification. In this presentation, I will provide a critical view on the use of canonical N isotope effects for water column and benthic denitrification in N isotope budgets and biogeochemical models. I will focus on the benthic environment, providing observational and model data, which suggest that the N isotope effect of N2 loss from ocean sediments may be as high as 5 ‰, significantly larger than assumed by earlier work. I will also address the potential impact of suboxic N2 producing processes other than denitrification (such as anammox) on the δ15N of the oceanic fixed N inventory, and I will discuss the implications for the global N-isotope balance, questioning current ideas with regards to the state of balance of the modern N budget.

  10. Assessing the Utility of Hydrogen, Carbon and Nitrogen Stable Isotopes in Estimating Consumer Allochthony in Two Shallow Eutrophic Lakes.

    PubMed

    Syväranta, Jari; Scharnweber, Kristin; Brauns, Mario; Hilt, Sabine; Mehner, Thomas

    2016-01-01

    Hydrogen stable isotopes (δ2H) have recently been used to complement δ13C and δ15N in food web studies due to their potentially greater power to separate sources of organic matter in aquatic food webs. However, uncertainties remain regarding the use of δ2H, since little is known about the potential variation in the amount of exchangeable hydrogen (Hex) among common sample materials or the patterns of δ2H when entire food webs are considered. We assessed differences in Hex among the typical sample materials in freshwater studies and used δ2H, δ13C and δ15N to compare their effectiveness in tracing allochthonous matter in food webs of two small temperate lakes. Our results showed higher average amounts of Hex in animal tissues (27% in fish and macroinvertebrates, 19% in zooplankton) compared to most plant material (15% in terrestrial plants and 8% in seston/periphyton), with the exception of aquatic vascular plants (23%, referred to as macrophytes). The amount of Hex correlated strongly with sample lipid content (inferred from C:N ratios) in fish and zooplankton samples. Overall, the three isotopes provided good separation of sources (seston, periphyton, macrophytes and allochthonous organic matter), particularly the δ2H followed by δ13C. Aquatic macrophytes revealed unexpectedly high δ2H values, having more elevated δ2H values than terrestrial organic matter with direct implications for estimating consumer allochthony. Organic matter from macrophytes significantly contributed to the food webs in both lakes highlighting the need to include macrophytes as a potential source when using stable isotopes to estimate trophic structures and contributions from allochthonous sources.

  11. Assessing the Utility of Hydrogen, Carbon and Nitrogen Stable Isotopes in Estimating Consumer Allochthony in Two Shallow Eutrophic Lakes

    PubMed Central

    Syväranta, Jari; Scharnweber, Kristin; Brauns, Mario; Hilt, Sabine; Mehner, Thomas

    2016-01-01

    Hydrogen stable isotopes (δ2H) have recently been used to complement δ13C and δ15N in food web studies due to their potentially greater power to separate sources of organic matter in aquatic food webs. However, uncertainties remain regarding the use of δ2H, since little is known about the potential variation in the amount of exchangeable hydrogen (Hex) among common sample materials or the patterns of δ2H when entire food webs are considered. We assessed differences in Hex among the typical sample materials in freshwater studies and used δ2H, δ13C and δ15N to compare their effectiveness in tracing allochthonous matter in food webs of two small temperate lakes. Our results showed higher average amounts of Hex in animal tissues (27% in fish and macroinvertebrates, 19% in zooplankton) compared to most plant material (15% in terrestrial plants and 8% in seston/periphyton), with the exception of aquatic vascular plants (23%, referred to as macrophytes). The amount of Hex correlated strongly with sample lipid content (inferred from C:N ratios) in fish and zooplankton samples. Overall, the three isotopes provided good separation of sources (seston, periphyton, macrophytes and allochthonous organic matter), particularly the δ2H followed by δ13C. Aquatic macrophytes revealed unexpectedly high δ2H values, having more elevated δ2H values than terrestrial organic matter with direct implications for estimating consumer allochthony. Organic matter from macrophytes significantly contributed to the food webs in both lakes highlighting the need to include macrophytes as a potential source when using stable isotopes to estimate trophic structures and contributions from allochthonous sources. PMID:27167517

  12. Thaumarchaeotes abundant in refinery nitrifying sludges express amoA but are not obligate autotrophic ammonia oxidizers

    PubMed Central

    Mußmann, Marc; Brito, Ivana; Pitcher, Angela; Sinninghe Damsté, Jaap S.; Hatzenpichler, Roland; Richter, Andreas; Nielsen, Jeppe L.; Nielsen, Per Halkjær; Müller, Anneliese; Daims, Holger; Wagner, Michael; Head, Ian M.

    2011-01-01

    Nitrification is a core process in the global nitrogen cycle that is essential for the functioning of many ecosystems. The discovery of autotrophic ammonia-oxidizing archaea (AOA) within the phylum Thaumarchaeota has changed our perception of the microbiology of nitrification, in particular since their numerical dominance over ammonia-oxidizing bacteria (AOB) in many environments has been revealed. These and other data have led to a widely held assumption that all amoA-encoding members of the Thaumarchaeota (AEA) are autotrophic nitrifiers. In this study, 52 municipal and industrial wastewater treatment plants were screened for the presence of AEA and AOB. Thaumarchaeota carrying amoA were detected in high abundance only in four industrial plants. In one plant, thaumarchaeotes closely related to soil group I.1b outnumbered AOB up to 10,000-fold, and their numbers, which can only be explained by active growth in this continuous culture system, were two to three orders of magnitude higher than could be sustained by autotrophic ammonia oxidation. Consistently, 14CO2 fixation could only be detected in AOB but not in AEA in actively nitrifying sludge from this plant via FISH combined with microautoradiography. Furthermore, in situ transcription of archaeal amoA, and very weak in situ labeling of crenarchaeol after addition of 13CO2, was independent of the addition of ammonium. These data demonstrate that some amoA-carrying group I.1b Thaumarchaeota are not obligate chemolithoautotrophs. PMID:21930919

  13. Assessment of nitrogen and oxygen isotopic fractionation during nitrification and its expression in the marine environment.

    PubMed

    Casciotti, Karen L; Buchwald, Carolyn; Santoro, Alyson E; Frame, Caitlin

    2011-01-01

    Nitrification is a microbially-catalyzed process whereby ammonia (NH(3)) is oxidized to nitrite (NO(2)(-)) and subsequently to nitrate (NO(3)(-)). It is also responsible for production of nitrous oxide (N(2)O), a climatically important greenhouse gas. Because the microbes responsible for nitrification are primarily autotrophic, nitrification provides a unique link between the carbon and nitrogen cycles. Nitrogen and oxygen stable isotope ratios have provided insights into where nitrification contributes to the availability of NO(2)(-) and NO(3)(-), and where it constitutes a significant source of N(2)O. This chapter describes methods for determining kinetic isotope effects involved with ammonia oxidation and nitrite oxidation, the two independent steps in the nitrification process, and their expression in the marine environment. It also outlines some remaining questions and issues related to isotopic fractionation during nitrification.

  14. Carbon stable isotopes as indicators of coastal eutrophication.

    PubMed

    Oczkowski, Autumn; Markham, Erin; Hanson, Alana; Wigand, Cathleen

    2014-04-01

    Coastal ecologists and managers have frequently used nitrogen stable isotopes (delta15N) to trace and monitor sources of anthropogenic nitrogen (N) in coastal ecosystems. However, the interpretation of delta15N data can often be challenging, as the isotope values fractionate substantially due to preferential retention and uptake by biota. There is a growing body of evidence that carbon isotopes may be a useful alternative indicator for eutrophication, as they may be sensitive to changes in primary production that result from anthropogenic nutrient inputs. We provide three examples of systems where delta13C values sensitively track phytoplankton production. First, earlier (1980s) mesocosm work established positive relationships between delta13C and dissolved inorganic nitrogen and dissolved silica concentrations. Consistent with these findings, a contemporary mesocosm experiment designed to replicate a temperate intertidal salt marsh environment also demonstrated that the system receiving supplementary nutrient additions had higher nutrient concentrations, higher chlorophyll concentrations, and higher delta13C values. This trend was particularly pronounced during the growing season, with differences less evident during senescence. And finally, these results were replicated in the open waters of Narragansett Bay, Rhode Island, USA, during a spring phytoplankton bloom. These three examples, taken together with the pre-existing body of literature, suggest that, at least in autotrophic, phytoplankton-dominated systems, delta13C values can be a useful and sensitive indicator of eutrophication.

  15. [Effects of Land Use Type on Soil Microbial Biomass Carbon and Nitrogen in Water-Stable Aggregates in Jinyun Mountain].

    PubMed

    Li, Zeng-quan; Jiang, Chang-sheng; Hao, Qing-ju

    2015-11-01

    In this study, four land use types including subtropical evergreen broad-leaved forest (abbreviation: forest), sloping farmland, orchard and abandoned land were selected to collect soil samples from 0 to 60 cm depth at the same altitude in Jinyun Mountain. Four sizes of large macroaggregates (> 2 mm), small macroaggregates (0.25-2 mm), microaggregates (0.053-0.25 mm) and silt + clay (< 0.053 mm) were achieved by wet sieving method and the contents of microbial biomass carbon (MBC) and microbial biomass nitrogen (MBN) in each aggregate fraction were measured to study the impacts of the different land use types on MBC and MBN in soil aggregates. The results showed that the contents of MBC and MBN in all aggregates in the four land use types decreased with the increasing soil depth. Except large macroaggregetes, the contents of MBC and MBN in the other three soil aggregates decreased when the forest was reclamated into orchard and sloping farmland. MBC and MBN contents in large macroaggregates, small macroaggregates and microaggregates all increased when the sloping farmland was abandoned. The storages of organic carbon and nitrogen in soil depth of 0-60 cm in the four proportions were calculated by the equivalent soil mass method. The results revealed that MBC storages in the other three sizes except silt + clay were higher in the forest than those in orchard and sloping land. And MBC storages in the all aggregates were higher in the abandoned land than those in the sloping land. MBN storages in small macroaggregates and microaggregates were higher in the forest than those in orchard and sloping land. And MBN storages in the other three aggregates except silt + clay were higher in the abandoned land than those in the sloping land. Generally speaking, the storages of MBC in soil aggregates of forest and abandoned land were higher than in orchard and sloping land, MBN storage in soil aggregates of forest was nearly equal to the storage in orchard. However, the storages

  16. Total Mercury, Methylmercury, and Carbon and Nitrogen Stable Isotope Data for Biota from Selected Streams in Oregon, Wisconsin, and Florida, 2002-04

    USGS Publications Warehouse

    Chasar, Lia C.; Scudder, Barbara C.; Bell, Amanda H.; Wentz, Dennis A.; Brigham, Mark E.

    2008-01-01

    The U.S. Geological Survey National Water-Quality Assessment Program conducted a multidisciplinary study to investigate the bioaccumulation of mercury from 2002 to 2004. Study areas were located in Oregon, Wisconsin, and Florida. Each study area included one urban site, and one or two nonurban sites that had the following attributes: high-percent wetland or low-percent wetland. Periphyton, macroinvertebrates, and forage fish were collected twice per year (during 2003 and 2004) to capture seasonality. Top predators, specifically largemouth bass (Micropterus salmoides), brown trout (Salmo trutta), and cutthroat trout (Oncorhynchus clarkii), were collected once per year (Oregon, Wisconsin, and Florida in 2003; Florida only in 2004). All biota were identified to the lowest possible taxonomic category and were analyzed for mercury and stable carbon and nitrogen isotopes. Periphyton and invertebrates were analyzed for total mercury and methylmercury; fish were analyzed for total mercury only. This report presents (1) methodology and data on mercury, methylmercury, stable isotopes, and (2) other ecologically relevant measurements in biological tissues of periphyton, invertebrates, forage fish, and predator fish.

  17. Distribution of trace elements in organs of six species of cetaceans from the Ligurian Sea (Mediterranean), and the relationship with stable carbon and nitrogen ratios.

    PubMed

    Capelli, R; Das, K; Pellegrini, R De; Drava, G; Lepoint, G; Miglio, C; Minganti, V; Poggi, R

    2008-02-15

    Mercury (total and organic), cadmium, lead, copper, iron, manganese, selenium and zinc concentrations were measured in different organs of 6 different cetacean species stranded in an area of extraordinary ecological interest (Cetaceans' Sanctuary of the Mediterranean Sea) along the coast of the Ligurian Sea (North-West Mediterranean). Stable-isotopes ratios of carbon ((13)C/(12)C) and nitrogen ((15)N/(14)N) were also measured in the muscle. A significant relationship exists between (15)N/(14)N, mercury concentration and the trophic level. The distribution of essential and non-essential trace elements was studied on several organs, and a significant relationship between selenium and mercury, with a molar ratio close to 1, was found in the cetaceans' kidney, liver and spleen, regardless of their species. High selenium concentrations are generally associated with a low organic to total mercury ratio. While narrow ranges of concentrations were observed for essential elements in most organs, mercury and selenium concentrations are characterised by a wide range of variation. Bio-accumulation and bio-amplification processes in cetaceans can be better understood by comparing trace element concentrations with the stable-isotopes data.

  18. Food web of a confined and anthropogenically affected coastal basin (the Mar Piccolo of Taranto) revealed by carbon and nitrogen stable isotopes analyses.

    PubMed

    Bongiorni, Lucia; Fiorentino, Federica; Auriemma, Rocco; Aubry, Fabrizio Bernardi; Camatti, Elisa; Camin, Federica; Nasi, Federica; Pansera, Marco; Ziller, Luca; Grall, Jacques

    2016-07-01

    Carbon and nitrogen stable isotope analysis was used to examine the food web of the Mar Piccolo of Taranto, a coastal basin experiencing several anthropogenic impacts. Main food sources (algal detritus, seaweeds, particulate organic matter (POM) and sediment organic matter (SOM)) and benthic and pelagic consumers were collected during two contrasting seasons (June and April), at four sites distributed over two inlets, and characterized by different level of confinements, anthropogenic inputs and the presence of mussels farming. δ(13)C values of organic sources revealed an important contribution of POM to both planktonic and benthic pathways, as well as the influence of terrigenous inputs within both inlets, probably due to high seasonal land runoff. Although δ(13)C of both sources and consumers varied little between sampling sites and dates, δ(15)N spatial variability was higher and clearly reflected the organic enrichment in the second inlet as well as the uptake of anthropogenically derived material by benthic consumers. On the other hand, within the first inlet, the isotopic composition of consumers did not change in response to chemical contamination. However, the impact of polluted sediments near the Navy Arsenal in the first inlet was detectable at the level of the macrobenthic trophic structure, showing high dominance of motile, upper level consumers capable to face transient conditions and the reduction of the more resident deposit feeders. We therefore underline the great potential of matching stable isotope analysis with quantitative studies of community structure to assess the effects of multiple anthropogenic stressors.

  19. Influence of Reproduction on Stable-Isotope Ratios: Nitrogen and Carbon Isotope Discrimination between Mothers, Fetuses, and Milk in the Fin Whale, a Capital Breeder.

    PubMed

    Borrell, A; Gómez-Campos, E; Aguilar, A

    2016-01-01

    In mammals, the influence of gestation and lactation on the tissue stable-isotope ratios of females, fetuses, and milk remains poorly understood. Here we investigate the incidence of these events on δ(13)C and δ(15)N values in fin whales sampled off northwestern Spain between 1983 and 1985. The effect of gestation on tissue stable-isotope ratios was examined in the muscle of pregnant females (n = 13) and their fetuses (n = 10) and that of lactation in the muscle of nursing females (n = 21) and their milk (n = 25). Results suggest that fetuses are enriched compared to their mothers in both (15)N (Δ(15)N = 1.5‰) and (13)C (Δ(13)C =1.1‰), while, compared to muscle, milk is enriched in (15)N (Δ(15)N = 0.3‰) but depleted in (13)C (Δ(13)C = -0.62‰). This pattern is consistent with that previously observed for other species that, like the fin whale, rely on endogenous energy during reproduction, and it substantiates a general difference in the physiological processing of nitrogen and carbon balances between income and capital breeders. These findings are relevant to the understanding of the energetic balance of mammals during gestation and lactation and are central when inferences on trophic ecology are drawn from isotopic values of reproductive females.

  20. Screening nitrogen-rich bases and oxygen-rich acids by theoretical calculations for forming highly stable salts.

    PubMed

    Zhang, Xueli; Gong, Xuedong

    2014-08-04

    Nitrogen-rich heterocyclic bases and oxygen-rich acids react to produce energetic salts with potential application in the field of composite explosives and propellants. In this study, 12 salts formed by the reaction of the bases 4-amino-1,2,4-trizole (A), 1-amino-1,2,4-trizole (B), and 5-aminotetrazole (C), upon reaction with the acids HNO3 (I), HN(NO2 )2 (II), HClO4 (III), and HC(NO2 )3 (IV), are studied using DFT calculations at the B97-D/6-311++G** level of theory. For the reactions with the same base, those of HClO4 are the most exothermic and spontaneous, and the most negative Δr Gm in the formation reaction also corresponds to the highest decomposition temperature of the resulting salt. The ability of anions and cations to form hydrogen bonds decreases in the order NO3 (-) >N(NO2 )2 (-) >ClO4 (-) >C(NO2 )3 (-) , and C(+) >B(+) >A(+) . In particular, those different cation abilities are mainly due to their different conformations and charge distributions. For the salts with the same anion, the larger total hydrogen-bond energy (EH,tot ) leads to a higher melting point. The order of cations and anions on charge transfer (q), second-order perturbation energy (E2 ), and binding energy (Eb ) are the same to that of EH,tot , so larger q leads to larger E2 , Eb , and EH,tot . All salts have similar frontier orbitals distributions, and their HOMO and LUMO are derived from the anion and the cation, respectively. The molecular orbital shapes are kept as the ions form a salt. To produce energetic salts, 5-aminotetrazole and HClO4 are the preferred base and acid, respectively. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  1. Meta-analysis of amino acid stable nitrogen isotope ratios for estimating trophic position in marine organisms.

    PubMed

    Nielsen, Jens M; Popp, Brian N; Winder, Monika

    2015-07-01

    Estimating trophic structures is a common approach used to retrieve information regarding energy pathways, predation, and competition in complex ecosystems. The application of amino acid (AA) compound-specific nitrogen (N) isotope analysis (CSIA) is a relatively new method used to estimate trophic position (TP) and feeding relationships in diverse organisms. Here, we conducted the first meta-analysis of δ(15)N AA values from measurements of 359 marine species covering four trophic levels, and compared TP estimates from AA-CSIA to literature values derived from food items, gut or stomach content analysis. We tested whether the AA trophic enrichment factor (TEF), or the (15)N enrichment among different individual AAs is constant across trophic levels and whether inclusion of δ(15)N values from multiple AAs improves TP estimation. For the TEF of glutamic acid relative to phenylalanine (Phe) we found an average value of 6.6‰ across all taxa, which is significantly lower than the commonly applied 7.6‰. We found that organism feeding ecology influences TEF values of several trophic AAs relative to Phe, with significantly higher TEF values for herbivores compared to omnivores and carnivores, while TEF values were also significantly lower for animals excreting urea compared to ammonium. Based on the comparison of multiple model structures using the metadata of δ(15)N AA values we show that increasing the number of AAs in principle improves precision in TP estimation. This meta-analysis clarifies the advantages and limitations of using individual δ(15)N AA values as tools in trophic ecology and provides a guideline for the future application of AA-CSIA to food web studies.

  2. Impact of different nitrogen emission sources on tree physiology as assessed by a triple stable isotope approach

    NASA Astrophysics Data System (ADS)

    Guerrieri, M. R.; Siegwolf, R. T. W.; Saurer, M.; Jäggi, M.; Cherubini, P.; Ripullone, F.; Borghetti, M.

    The importance that nitrogen (N) deposition has in driving the carbon (C) sequestration of forests has recently been investigated using both experimental and modeling approaches. Whether increased N deposition has positive or negative effects on such ecosystems depends on the status of the N and the duration of the deposition. By combining δ13C, δ18O, δ15N and dendrochronological approaches, we analyzed the impact of two different sources of NO x emissions on two tree species, namely: a broadleaved species ( Quercus cerris) that was located close to an oil refinery in Southern Italy, and a coniferous species ( Picea abies) located close to a freeway in Switzerland. Variations in the ci/ ca ratio and the distinction between stomatal and photosynthetic responses to NO x emissions in trees were assessed using a conceptual model, which combines δ13C and δ18O. δ15N in leaves, needles and tree rings was found to be a bioindicator of N input from anthropogenic emissions, especially at the oil refinery site. We observed that N fertilization had a stimulatory effect on tree growth near the oil refinery, while the opposite effect was found for trees at the freeway site. Changes in the ci/ ca ratio were mostly related to variations in δ13C at the freeway site and, thus, were driven by photosynthesis. At the oil refinery site they were mainly related to stomatal conductance, as assessed using δ18O. This study demonstrates that a single method approach does not always provide a complete picture of which physiological traits are more affected by N emissions. The triple isotope approach combined with dendrochronological analyses proved to be a very promising tool for monitoring the ecophysiological responses of trees to long-term N deposition.

  3. Molecular and Stable Isotope Investigation of Nitrite Respiring Bacterial Communities Capable of Anaerobic Ammonium Oxidation (ANAMMOX) and Denitrifying Anaerobic Methane Oxidation (DAMO) in Nitrogen Contaminated Groundwater

    NASA Astrophysics Data System (ADS)

    Song, B.; Hirsch, M.; Taylor, J.; Smith, R. L.; Repert, D.; Tobias, C. R.

    2010-12-01

    Anaerobic ammonium oxidation (ANAMMOX) and denitrifying anaerobic methane oxidation (DAMO) are two recently discovered N2 production pathways in the microbial nitrogen cycle. ANAMMOX has been relatively well investigated in various aquatic ecosystems, while DAMO has been examined only in freshwater wetlands. However, neither ANAMMOX nor DAMO have been studied in groundwater ecosystems as microbial N removal processes where they could compliment or compete with denitrification to remediate N contaminated aquifers. Thus, we conducted molecular and stable isotope analyses to detect and measure ANAMMOX and DAMO in a nitrogen contaminated aquifer on Cape Cod, Massachusetts. The study site has a plume of nitrogen contaminated groundwater as a result of continuous discharge of treated wastewater over 60 years. Groundwater was collected from multiport sampling devices installed at two sites, near the waste-water disposal location (A) and more than 3 km down gradient (B) along the contamination plume. Biomass was collected from water samples for DNA extraction and 15N tracer incubation experiments. PCR with specific 16S rRNA gene primers detected the presence of ANAMMOX and DAMO bacteria at both sites. Phylogenetic analysis of 16S rRNA genes revealed that the ANAMMOX community at site A was most associated with Kuenenia spp. while site B had a community more closely related to Brocadia spp. The DAMO communities at the two sites were quite different based on 16S rRNA gene analysis. The communities at site B are closely associated with Candidatus “Methylomirabilis oxyfera”, which is the first enriched DAMO culture. Most of the 16S rRNA sequences detected in site A were related to those found in other DAMO enrichment cultures established from a eutrophic ditch sediment. In order to determine active members of ANAMMOX communities, the transcriptional expression of hydrazine oxidase (hzo) and hydrazine hydrolase (hh) genes was examined at both sites. In addition, 15N tracer

  4. Using Stable Isotopes of Carbon and Nitrogen to Mark Wild Populations of Anopheles and Aedes Mosquitoes in South-Eastern Tanzania

    PubMed Central

    Opiyo, Mercy A.; Hamer, Gabriel L.; Lwetoijera, Dickson W.; Auckland, Lisa D.; Majambere, Silas; Okumu, Fredros O.

    2016-01-01

    Background Marking wild mosquitoes is important for understanding their ecology, behaviours and role in disease transmission. Traditional insect marking techniques include using fluorescent dyes, protein labels, radioactive labels and tags, but such techniques have various limitations; notably low marker retention and inability to mark wild mosquitoes at source. Stable isotopes are gaining wide spread use for non-invasive marking of arthropods, permitting greater understanding of mosquito dispersal and responses to interventions. We describe here a simple technique for marking naturally-breeding malaria and dengue vectors using stable isotopes of nitrogen (15N) and carbon (13C), and describe potential field applications. Methods We created man-made aquatic mosquito habitats and added either 15N-labelled potassium nitrate or 13C-labelled glucose, leaving non-adulterated habitats as controls. We then allowed wild mosquitoes to lay eggs in these habitats and monitored their development in situ. Pupae were collected promptly as they appeared and kept in netting cages. Emergent adults (in pools of ~4 mosquitoes/pool) and individually stored pupae were desiccated and analysed using Isotope Ratio Mass Spectrometry (IRMS). Findings Anopheles gambiae s.l and Aedes spp. from enriched 13C and enriched 15N larval habitats had significantly higher isotopic levels than controls (P = 0.005), and both isotopes produced sufficient distinction between marked and unmarked mosquitoes. Mean δ15N for enriched females and males were 275.6±65.1 and 248.0±54.6, while mean δ15N in controls were 2.1±0.1 and 3.9±1.7 respectively. Similarly, mean δ13C for enriched females and males were 36.08±5.28 and 38.5±6.86, compared to -4.3±0.2 and -7.9±3.6 in controls respectively. Mean δ15N and δ13C was significantly higher in any pool containing at least one enriched mosquito compared to pools with all unenriched mosquitoes, P<0.001. In all cases, there were variations in standardized

  5. Using Stable Isotopes of Carbon and Nitrogen to Mark Wild Populations of Anopheles and Aedes Mosquitoes in South-Eastern Tanzania.

    PubMed

    Opiyo, Mercy A; Hamer, Gabriel L; Lwetoijera, Dickson W; Auckland, Lisa D; Majambere, Silas; Okumu, Fredros O

    2016-01-01

    Marking wild mosquitoes is important for understanding their ecology, behaviours and role in disease transmission. Traditional insect marking techniques include using fluorescent dyes, protein labels, radioactive labels and tags, but such techniques have various limitations; notably low marker retention and inability to mark wild mosquitoes at source. Stable isotopes are gaining wide spread use for non-invasive marking of arthropods, permitting greater understanding of mosquito dispersal and responses to interventions. We describe here a simple technique for marking naturally-breeding malaria and dengue vectors using stable isotopes of nitrogen (15N) and carbon (13C), and describe potential field applications. We created man-made aquatic mosquito habitats and added either 15N-labelled potassium nitrate or 13C-labelled glucose, leaving non-adulterated habitats as controls. We then allowed wild mosquitoes to lay eggs in these habitats and monitored their development in situ. Pupae were collected promptly as they appeared and kept in netting cages. Emergent adults (in pools of ~4 mosquitoes/pool) and individually stored pupae were desiccated and analysed using Isotope Ratio Mass Spectrometry (IRMS). Anopheles gambiae s.l and Aedes spp. from enriched 13C and enriched 15N larval habitats had significantly higher isotopic levels than controls (P = 0.005), and both isotopes produced sufficient distinction between marked and unmarked mosquitoes. Mean δ15N for enriched females and males were 275.6±65.1 and 248.0±54.6, while mean δ15N in controls were 2.1±0.1 and 3.9±1.7 respectively. Similarly, mean δ13C for enriched females and males were 36.08±5.28 and 38.5±6.86, compared to -4.3±0.2 and -7.9±3.6 in controls respectively. Mean δ15N and δ13C was significantly higher in any pool containing at least one enriched mosquito compared to pools with all unenriched mosquitoes, P<0.001. In all cases, there were variations in standardized isotopic ratios between mosquito

  6. Strong evidence for terrestrial support of zooplankton in small lakes based on stable isotopes of carbon, nitrogen, and hydrogen

    USGS Publications Warehouse

    Cole, J.J.; Carpenter, S.R.; Kitchell, J.; Pace, M.L.; Solomon, C.T.; Weidel, B.

    2011-01-01

    Cross-ecosystem subsidies to food webs can alter metabolic balances in the receiving (subsidized) system and free the food web, or particular consumers, from the energetic constraints of local primary production. Although cross-ecosystem subsidies between terrestrial and aquatic systems have been well recognized for benthic organisms in streams, rivers, and the littoral zones of lakes, terrestrial subsidies to pelagic consumers are more difficult to demonstrate and remain controversial. Here, we adopt a unique approach by using stable isotopes of H, C, and N to estimate terrestrial support to zooplankton in two contrasting lakes. Zooplankton (Holopedium, Daphnia, and Leptodiaptomus) are comprised of ???20-40% of organic material of terrestrial origin. These estimates are as high as, or higher than, prior measures obtained by experimentally manipulating the inorganic 13C content of these lakes to augment the small, natural contrast in 13C between terrestrial and algal photosynthesis. Our study gives credence to a growing literature, which we review here, suggesting that significant terrestrial support of pelagic crustaceans (zooplankton) is widespread.

  7. Strong evidence for terrestrial support of zooplankton in small lakes based on stable isotopes of carbon, nitrogen, and hydrogen

    PubMed Central

    Cole, Jonathan J.; Carpenter, Stephen R.; Kitchell, Jim; Pace, Michael L.; Solomon, Christopher T.; Weidel, Brian

    2011-01-01

    Cross-ecosystem subsidies to food webs can alter metabolic balances in the receiving (subsidized) system and free the food web, or particular consumers, from the energetic constraints of local primary production. Although cross-ecosystem subsidies between terrestrial and aquatic systems have been well recognized for benthic organisms in streams, rivers, and the littoral zones of lakes, terrestrial subsidies to pelagic consumers are more difficult to demonstrate and remain controversial. Here, we adopt a unique approach by using stable isotopes of H, C, and N to estimate terrestrial support to zooplankton in two contrasting lakes. Zooplankton (Holopedium, Daphnia, and Leptodiaptomus) are comprised of ≈20–40% of organic material of terrestrial origin. These estimates are as high as, or higher than, prior measures obtained by experimentally manipulating the inorganic 13C content of these lakes to augment the small, natural contrast in 13C between terrestrial and algal photosynthesis. Our study gives credence to a growing literature, which we review here, suggesting that significant terrestrial support of pelagic crustaceans (zooplankton) is widespread. PMID:21245299

  8. Mercury concentrations in Southern Beaufort Sea polar bears: variation based on stable isotopes of carbon and nitrogen.

    PubMed

    Cardona-Marek, Tamara; Knott, Katrina K; Meyer, Benjamin E; O'Hara, Todd M

    2009-07-01

    Total Hg concentration was measured in hair and whole blood of 52 adult Southern Beaufort Sea polar bears (Ursus maritimus) captured in the spring of 2005. Stable isotopic signatures (i.e., 13C/12C, delta13C; 15N/14N, delta15N) in hair and two blood compartments (packed blood cells/clot and serum) were determined to assess the variation of Hg concentrations among polar bears in relation to their feeding ecology and other biological factors. Concentrations of Hg in hair and blood (2.2-23.9 microg/g dry wt and 0.007-0.213 microg/g wet wt, respectively) were within the range of values previously reported for polar bears in Canada and East Greenland. Mercury concentration in hair from females was higher than that in hair from males, and concentration was related to interactions between delta13C, delta15N, and longitude of capture location. Mercury concentrations in hair were inversely correlated to delta13C in hair and blood, suggesting that polar bears with greater total Hg concentrations fed more on pelagic prey, such as ringed seals or beluga whale, than on benthic prey. Variability in Hg concentrations in polar bear hair and blood may be the result of intraspecific or regional variation in prey selection rather than strictly trophic level interactions.

  9. Determination of origin of ephedrine used as precursor for illicit methamphetamine by carbon and nitrogen stable isotope ratio analysis.

    PubMed

    Kurashima, Naoki; Makino, Yukiko; Sekita, Setsuko; Urano, Yasuteru; Nagano, Tetsuo

    2004-07-15

    The sale of ephedrine, one of the precursors of methamphetamine, is strictly controlled and monitored in various countries to prevent the production of illicit methamphetamine. There are three kinds of production scheme for ephedrine manufacture, and it is very useful for precursor control to investigate the origin of ephedrine used for the synthesis of illicit methamphetamine. By means of stable isotope ratio mass spectrometry (IR-MS), we investigated the origin of ephedrine based on the delta(13)C and delta(15)N values. The various origins of ephedrine (biosynthetic, semisynthetic, or synthetic) could be discriminated clearly by using these values. The delta(15)N values of synthetic ephedrine were more negative than those of ephedrine from other sources. By the repeated distillation of methylamine in our laboratory, we confirmed that this could be due to isotope separation during distillation for the purification of methylamine used for ephedrine synthesis. The values for ephedrine used as the precursor were well-correlated with those for methamphetamine synthesized from it. This drug characterization analysis should be useful to illuminate the origin of the precursors used for clandestine methamphetamine and to trace the diversion of medicinal ephedrine for illicit manufacture of methamphetamine.

  10. Estimating autotrophic respiration in streams using daily metabolism data

    EPA Science Inventory

    Knowing the fraction of gross primary production (GPP) that is immediately respired by autotrophs and their closely associated heterotrophs (ARf) is necessary to understand the trophic base and carbon spiraling in streams. We show a means to estimate ARf from daily metabolism da...

  11. Estimating autotrophic respiration in streams using daily metabolism data

    EPA Science Inventory

    Knowing the fraction of gross primary production (GPP) that is immediately respired by autotrophs and their closely associated heterotrophs (ARf) is necessary to understand the trophic base and carbon spiraling in streams. We show a means to estimate ARf from daily metabolism da...

  12. General medium for the autotrophic cultivation of acetogens.

    PubMed

    Groher, Anna; Weuster-Botz, Dirk

    2016-10-01

    Syngas fermentation, a microbial process in which synthesis gas serves as a substrate for acetogens, has attracted increasing interest in the last few years. For the purposeful selection of acetogens for various applications, it would be useful to characterize and compare the process performances of as many autotrophic strains as possible under identical process conditions. Unfortunately, all the media compositions so far recommended for syngas fermentation differ considerably with respect to each individual strain. Therefore, a general medium for syngas fermentation was designed. The suitability of this new general-acetogen medium (GA-medium) was proven based on the autotrophic batch cultivation of Acetobacterium fimetarium, Acetobacterium wieringae, Blautia hydrogenotrophica, Clostridium magnum, Eubacterium aggregans, Sporomusa acidovorans, Sporomusa ovata and Terrisporobacter mayombei in anaerobic flasks with an initial gas phase of H2:CO2 (66:34) (P = 200 kPa). A comparison of the autotrophic batch processes with this medium revealed T. mayombei as the bacterium with the highest maximum growth rate of 5.77 day(-1) which was more than 10 times higher than the lowest identified maximum growth rate of A. fimetarium. The maximum growth rates of A. wieringae, C. magnum and S. acidovorans were all in the same order of magnitude around 1.7 day(-1). The newly designed GA-medium offers the possibility to compare autotrophic process performances of different acetogens under similar conditions absent the effects of various media compositions.

  13. Tracing seasonal nitrate sources and loads in the San Joaquin River using nitrogen and oxygen stable isotopes

    NASA Astrophysics Data System (ADS)

    Young, M. B.; Kendall, C.; Silva, S.; Stringfellow, W. T.; Dahlgren, R. A.

    2007-12-01

    The San Joaquin River (SJR) is a heavily impacted river draining a major agricultural basin in central California. This river receives nitrate inputs from multiple point and non-point sources including agriculture, livestock, waste water treatment plants, septic systems, urban run-off, and natural soil leaching. Nitrate inputs to the SJR may play a significant role in driving algal blooms and reducing overall water quality. The San Joaquin River discharges into the San Francisco Bay-Delta ecosystem, and reduced water quality and large algal blooms in the SJR may play a significant role in driving critically low oxygen levels in the Stockton Deep Water Shipping Channel. Correct identification of the major nitrate sources to the SJR is important for coordinating mitigation efforts throughout the SJR-Delta-San Francisco Bay region. Measurements of the nitrogen and oxygen isotopic composition of nitrate were made monthly to bimonthly from 2005 through 2007 within the Lower SJR, major tributaries, and various other water input sources in order to assess spatial and temporal variations in nitrate inputs and cycling in this heavily impacted watershed. The oxygen and hydrogen isotopic composition of water was also measured to better distinguish water sources and identify changes in water inputs. A very wide range of δ15N-NO3 and δ18O-NO3 values were observed in the main stem SJR and tributaries. The δ15N values ranged from +2 to +17 ‰, and the δ18O values ranged from -1 to +18 ‰. Except for a major agricultural drain site (San Luis Drain), all the sites showed temporal changes in both δ15N-NO3 and δ18O-NO3 much greater than the differences seen between individual sites. In general, the δ15N values of nitrate in the larger tributary rivers (Merced, Tuolumne and Stanislaus) were much lower than those of the main stem SJR from April to May; however, after June the tributary values began to rise toward the values in the main stem river. Some of the highest δ15N-NO3

  14. Fate of process solution cyanide and nitrate at three nevada gold mines inferred from stable carbon and nitrogen isotope measurements

    USGS Publications Warehouse

    Johnson, C.A.; Grimes, D.J.; Rye, R.O.

    2000-01-01

    Stable isotope methods have been used to identify the mechanisms responsible for cyanide consumption at three heap-leach operations that process Carlin-type gold ores in Nevada, U.S.A. The reagent cyanide had ??15N values ranging from -5 to -2??? and ??13C values from -60 to -35???. The wide ??13C range reflects the use by different suppliers of isotopically distinct natural-gas feedstocks and indicates that isotopes may be useful in environmental studies where there is a need to trace cyanide sources. In heap-leach circuits displaying from 5 to 98% consumption of cyanide, barren-solution and pregnant-solution cyanide were isotopically indistinguishable. The similarity is inconsistent with cyanide loss predominantly by HCN offgassing (a process that in laboratory experiments caused substantial isotopic changes), but it is consistent with cyanide retention within the heaps as solids, a process that caused minimal isotopic changes in laboratory simulations, or with cyanide oxidation, which also appears to cause minimal changes. In many pregnant solutions cyanide was carried entirely as metal complexes, which is consistent with ferrocyanides having precipitated or cyanocomplexes having been adsorbed within the heaps. It is inferred that gaseous cyanide emissions from operations of this type are less important than has generally been thought and that the dissolution or desorption kinetics of solid species is an important control on cyanide elution when the spent heaps undergo rinsing. Nitrate, nitrite and ammonium had ??15N values of 1-16???. The data reflect isotopic fractionation during ammonia offgassing or denitrification of nitrate - particularly in reclaim ponds - but do not indicate the extent to which nitrate is derived from cyanide or from explosive residues. ?? The Institution of Mining and Metallurgy 2000.

  15. Carbon and nitrogen stable isotopes and metal concentration in food webs from a mining-impacted coastal lagoon.

    PubMed

    Marín-Guirao, Lázaro; Lloret, Javier; Marin, Arnaldo

    2008-04-01

    Two food webs from the Mar Menor coastal lagoon, differing in the distance from the desert-stream through which mining wastes were discharged, were examined by reference to essential (Zn and Cu) and non-essential (Pb and Cd) metal concentrations and stable isotopes content (C and N). The partial extraction technique applied, which reflects the availability of metals to organisms after sediment ingestion, showed higher bioavailable metal concentrations in sediments from the station influenced by the mining discharges, in agreement with the higher metal concentrations observed in organisms, which in many cases exceeded the regulatory limits established in Spanish legislation concerning seafood. Spatial differences in essential metal concentrations in the fauna suggest that several organisms are exposed to metal levels above their regulation capacity. Differences in isotopic composition were found between both food webs, the wadi-influenced station showing higher delta(15)N values and lower delta(13)C levels, due to the discharge of urban waste waters and by the entrance of freshwater and allochthonous marsh plants. The linear-regressions between trophic levels (as indicated by delta(15)N) and the metal content indicated that biomagnification does not occur. In the case of invertebrates, since the "handle strategy" of the species and the physiological requirements of the organisms, among other factors, determine the final concentration of a specific element, no clear relationships between trophic level and the metal content are to be expected. For their part, fish communities did not show clear patterns in the case of any of the analyzed metals, probably because most fish species have similar metal requirements, and because biological factors also intervened. Finally, since the study deals with metals, assumptions concerning trophic transfer factors calculation may not be suitable since the metal burden originates not only from the prey but also from adsorption over

  16. Modeling food web structure and selenium biomagnification in Lake Macquarie, New South Wales, Australia, using stable carbon and nitrogen isotopes.

    PubMed

    Schneider, Larissa; Maher, William A; Potts, Jaimie; Taylor, Anne M; Batley, Graeme E; Krikowa, Frank; Chariton, Anthony A; Gruber, Bernd

    2015-03-01

    As a consequence of coal-fired power station operations, elevated selenium concentrations have been reported in the sediments and biota of Lake Macquarie (New South Wales, Australia). In the present study, an ecosystem-scale model has been applied to determine how selenium in a seagrass food web is processed from sediments and water through diet to predators, using stable isotopes (δ(13) C and δ(15) N) to establish the trophic position of organisms. Trophic position, habitat, and feeding zone were examined as possible factors influencing selenium bioaccumulation. Selenium concentrations ranged from 0.2 μg/g dry weight in macroalgae species to 12.9 μg/g in the carnivorous fish Gerres subfasciatus. A mean magnification factor of 1.39 per trophic level showed that selenium is biomagnifying in the seagrass food web. Habitat and feeding zone influenced selenium concentrations in invertebrates, whereas feeding zone was the only significant factor influencing selenium concentrations in fish. The sediment-water partitioning coefficient (Kd ) of 4180 showed that partitioning of selenium entering the lake to particulate organic material (POM) is occurring, and consequently availability to food webs from POM is high. Trophic transfer factors (invertebrate = 1.9; fish = 1.2) were similar to those reported for other water bodies, showing that input source is not the main determinant of the magnitude of selenium bioaccumulation in a food web, but rather the initial partitioning of selenium into bioavailable POM. Environ Toxicol Chem 2015;34:608-617. © 2014 SETAC.

  17. Large-scale demonstration of the sulfate reduction autotrophic denitrification nitrification integrated (SANI(®)) process in saline sewage treatment.

    PubMed

    Wu, Di; Ekama, George A; Chui, Ho-Kwong; Wang, Bo; Cui, Yan-Xiang; Hao, Tian-Wei; van Loosdrecht, Mark C M; Chen, Guang-Hao

    2016-09-01

    Recently, the Sulfate reduction Autotrophic denitrification Nitrification Integrated (SANI(®)) process was developed for the removal of organics and nitrogen with sludge minimization in the treatment of saline sewage (with a Sulfate-to-COD ratio > 0.5 mg SO4(2-)-S/mg COD) generated from seawater used for toilet flushing or salt water intrusion. Previously investigated in lab- and pilot-scale, this process has now been scaled up to a 800-1000 m(3)/d full-scale demonstration plant. In this paper, the design and operating parameters of the SANI demo plant built in Hong Kong are analyzed. After a 4-month start-up period, a stable sulfur cycle-based biological nitrogen removal system having a hydraulic retention time (HRT) of 12.5 h was developed, thereby reducing the amount of space needed by 30-40% compared with conventional activated sludge (CAS) plants in Hong Kong. The demo plant satisfactorily met the local effluent discharge limits during both the summer and winter periods. In winter (sewage temperature of 21 ± 1 °C), the maximum volumetric loading rates for organic conversion, nitrification, and denitrification were 2 kg COD/(m(3)·d), 0.39 kg N/(m(3)·d), and 0.35 kg N/(m(3)·d), respectively. The biological sludge production rate of SANI process was 0.35 ± 0.08 g TSSproduced/g BOD5 (or 0.19 ± 0.05 g TSS/g COD), which is 60-70% lower than that of the CAS process in Hong Kong. While further process optimization is possible, this study demonstrates the SANI process can be potentially implemented for the treatment of saline sewage. Copyright © 2016 Elsevier Ltd. All rights reserved.

  18. Autotrophic CO2 fixation pathways in archaea (Crenarchaeota).

    PubMed

    Hügler, Michael; Huber, Harald; Stetter, Karl Otto; Fuchs, Georg

    2003-03-01

    Representative autotrophic and thermophilic archaeal species of different families of Crenarchaeota were examined for key enzymes of the known autotrophic CO(2) fixation pathways. Pyrobaculum islandicum ( Thermoproteaceae) contained key enzymes of the reductive citric acid cycle. This finding is consistent with the operation of this pathway in the related Thermoproteus neutrophilus. Pyrodictium abyssi and Pyrodictium occultum ( Pyrodictiaceae) contained ribulose 1,5-bisphosphate carboxylase, which was active in boiling water. Yet, phosphoribulokinase activity was not detectable. Operation of the Calvin cycle remains to be demonstrated. Ignicoccus islandicus and Ignicoccus pacificus ( Desulfurococcaceae) contained pyruvate oxidoreductase as potential carboxylating enzyme, but apparently lacked key enzymes of known pathways; their mode of autotrophic CO(2) fixation is at issue. Metallosphaera sedula, Acidianus ambivalens and Sulfolobus sp. strain VE6 ( Sulfolobaceae) contained key enzymes of a 3-hydroxypropionate cycle. This finding is in line with the demonstration of acetyl-coenzyme A (CoA) and propionyl-CoA carboxylase activities in the related Acidianus brierleyi and Sulfolobus metallicus. Enzymes of central carbon metabolism in Metallosphaera sedula were studied in more detail. Enzyme activities of the 3-hydroxypropionate cycle were strongly up-regulated during autotrophic growth, supporting their role in CO(2) fixation. However, formation of acetyl-CoA from succinyl-CoA could not be demonstrated, suggesting a modified pathway of acetyl-CoA regeneration. We conclude that Crenarchaeota exhibit a mosaic of three or possibly four autotrophic pathways. The distribution of the pathways so far correlates with the 16S-rRNA-based taxa of the Crenarchaeota.

  19. Systems and Photosystems: Cellular Limits of Autotrophic Productivity in Cyanobacteria

    PubMed Central

    Burnap, Robert L.

    2014-01-01

    Recent advances in the modeling of microbial growth and metabolism have shown that growth rate critically depends upon the optimal allocation of finite proteomic resources among different cellular functions and that modeling growth rates becomes more realistic with the explicit accounting for the costs of macromolecular synthesis, most importantly, protein expression. The “proteomic constraint” is considered together with its application to understanding photosynthetic microbial growth. The central hypothesis is that physical limits of cellular space (and corresponding solvation capacity) in conjunction with cell surface-to-volume ratios represent the underlying constraints on the maximal rate of autotrophic microbial growth. The limitation of cellular space thus constrains the size the total complement of macromolecules, dissolved ions, and metabolites. To a first approximation, the upper limit in the cellular amount of the total proteome is bounded this space limit. This predicts that adaptation to osmotic stress will result in lower maximal growth rates due to decreased cellular concentrations of core metabolic proteins necessary for cell growth owing the accumulation of compatible osmolytes, as surmised previously. The finite capacity of membrane and cytoplasmic space also leads to the hypothesis that the species-specific differences in maximal growth rates likely reflect differences in the allocation of space to niche-specific proteins with the corresponding diminution of space devoted to other functions including proteins of core autotrophic metabolism, which drive cell reproduction. An optimization model for autotrophic microbial growth, the autotrophic replicator model, was developed based upon previous work investigating heterotrophic growth. The present model describes autotrophic growth in terms of the allocation protein resources among core functional groups including the photosynthetic electron transport chain, light-harvesting antennae, and the

  20. Diet and habitat of the saiga antelope during the late Quaternary using stable carbon and nitrogen isotope ratios

    NASA Astrophysics Data System (ADS)

    Jürgensen, Jonathan; Drucker, Dorothée G.; Stuart, Anthony J.; Schneider, Matthias; Buuveibaatar, Bayarbaatar; Bocherens, Hervé

    2017-03-01

    Saiga antelope (Saiga tatarica) is one of the typical late Pleistocene species of the cold and arid mammoth steppe that covered a large area of northern hemisphere. The species is currently endangered and persists only in small areas of Central Asian steppe and desert ecosystems. The investigation of the ecology of the Pleistocene saiga using stable isotope ratios (δ13C, δ15N) aimed to decipher how different their diet and habitat were from those observed nowadays in relict populations. Up to 76 samples of bone collagen of ancient saiga from Western Europe, Siberia and Eastern Beringia were analysed and compared with 52 samples of hair and bone collagen of modern specimens from Kazahkstan, Russia and Mongolia. The δ13C values of the ancient saiga do not exhibit a clear trend over time. They cover the same range of values as the modern ones, from a C3-dominated to a C3-C4-dominated mixed diet (including probably Chenopodiaceae). In contrast, the δ15N values of fossil saigas are more variable and lower on average than the extant ones. The lowest δ15N values of ancient saiga are found around the Last Glacial Maximum, reflecting the influence of the cold conditions at that time. On the other hand, fossil saiga occupying the same regions as the historical and modern populations exhibit high δ15N values similar to the modern ones, confirming ecological continuity over time. Modern saiga is thus occupying just one of its potential diverse habitats they used in the past. Therefore, the extant saiga is not a refugee species confined to a suboptimal habitat. During the late Pleistocene, the saiga occupied a separate niche compared with the other ungulates of the mammoth steppe. However, this species could also adapt to a lichen-dominated diet normally seen in reindeer, leading to an isotopic overlap between the two species in south-western France and Alaska around the Last Glacial Maximum. This adaptation allowed a geographical expansion that does not correspond to a

  1. Identification of microbial populations assimilating nitrogen from RDX in munitions contaminated military training range soils by high sensitivity stable isotope probing.

    PubMed

    Andeer, Peter; Stahl, David A; Lillis, Lorraine; Strand, Stuart E

    2013-09-17

    The leaching of RDX (hexahydro-1,3,5-trinitro-1,3,5-triazine) from particulates deposited in live-fire military training range soils contributes to significant pollution of groundwater. In situ microbial degradation has been proposed as a viable method for onsite containment of RDX. However, there is only a single report of RDX degradation in training range soils and the soil microbial communities involved in RDX degradation were not identified. Here we demonstrate aerobic RDX degradation in soils taken from a target area of an Eglin Air Force Base bombing range, C52N Cat's Eye, (Eglin, Florida U.S.A.). RDX-degradation activity was spatially heterogeneous (found in less than 30% of initial target area field samples) and dependent upon the addition of exogenous carbon sources to the soils. Therefore, biostimulation (with exogenous carbon sources) and bioaugmentation may be necessary to sustain timely and effective in situ microbial biodegradation of RDX. High sensitivity stable isotope probing analysis of extracted soils incubated with fully labeled (15)N-RDX revealed several organisms with (15)N-labeled DNA during RDX-degradation, including xplA-bearing organisms. Rhodococcus was the most prominent genus in the RDX-degrading soil slurries and was completely labeled with (15)N-nitrogen from the RDX. Rhodococcus and Williamsia species isolated from these soils were capable of using RDX as a sole nitrogen source and possessed the genes xplB and xplA associated with RDX-degradation, indicating these genes may be suitable genetic biomarkers for assessing RDX degradation potential in soils. Other highly labeled species were primarily Proteobacteria, including: Mesorhizobium sp., Variovorax sp., and Rhizobium sp.

  2. Application of nitrogen and carbon stable isotopes (δ(15)N and δ(13)C) to quantify food chain length and trophic structure.

    PubMed

    Perkins, Matthew J; McDonald, Robbie A; van Veen, F J Frank; Kelly, Simon D; Rees, Gareth; Bearhop, Stuart

    2014-01-01

    Increasingly, stable isotope ratios of nitrogen (δ(15)N) and carbon (δ(13)C) are used to quantify trophic structure, though relatively few studies have tested accuracy of isotopic structural measures. For laboratory-raised and wild-collected plant-invertebrate food chains spanning four trophic levels we estimated nitrogen range (NR) using δ(15)N, and carbon range (CR) using δ(13)C, which are used to quantify food chain length and breadth of trophic resources respectively. Across a range of known food chain lengths we examined how NR and CR changed within and between food chains. Our isotopic estimates of structure are robust because they were calculated using resampling procedures that propagate variance in sample means through to quantified uncertainty in final estimates. To identify origins of uncertainty in estimates of NR and CR, we additionally examined variation in discrimination (which is change in δ(15)N or δ(13)C from source to consumer) between trophic levels and among food chains. δ(15)N discrimination showed significant enrichment, while variation in enrichment was species and system specific, ranged broadly (1.4‰ to 3.3‰), and importantly, propagated variation to subsequent estimates of NR. However, NR proved robust to such variation and distinguished food chain length well, though some overlap between longer food chains infers a need for awareness of such limitations. δ(13)C discrimination was inconsistent; generally no change or small significant enrichment was observed. Consequently, estimates of CR changed little with increasing food chain length, showing the potential utility of δ(13)C as a tracer of energy pathways. This study serves as a robust test of isotopic quantification of food chain structure, and given global estimates of aquatic food chains approximate four trophic levels while many food chains include invertebrates, our use of four trophic level plant-invertebrate food chains makes our findings relevant for a majority of

  3. Application of Nitrogen and Carbon Stable Isotopes (δ15N and δ13C) to Quantify Food Chain Length and Trophic Structure

    PubMed Central

    Perkins, Matthew J.; McDonald, Robbie A.; van Veen, F. J. Frank; Kelly, Simon D.; Rees, Gareth; Bearhop, Stuart

    2014-01-01

    Increasingly, stable isotope ratios of nitrogen (δ15N) and carbon (δ13C) are used to quantify trophic structure, though relatively few studies have tested accuracy of isotopic structural measures. For laboratory-raised and wild-collected plant-invertebrate food chains spanning four trophic levels we estimated nitrogen range (NR) using δ15N, and carbon range (CR) using δ13C, which are used to quantify food chain length and breadth of trophic resources respectively. Across a range of known food chain lengths we examined how NR and CR changed within and between food chains. Our isotopic estimates of structure are robust because they were calculated using resampling procedures that propagate variance in sample means through to quantified uncertainty in final estimates. To identify origins of uncertainty in estimates of NR and CR, we additionally examined variation in discrimination (which is change in δ15N or δ13C from source to consumer) between trophic levels and among food chains. δ15N discrimination showed significant enrichment, while variation in enrichment was species and system specific, ranged broadly (1.4‰ to 3.3‰), and importantly, propagated variation to subsequent estimates of NR. However, NR proved robust to such variation and distinguished food chain length well, though some overlap between longer food chains infers a need for awareness of such limitations. δ13C discrimination was inconsistent; generally no change or small significant enrichment was observed. Consequently, estimates of CR changed little with increasing food chain length, showing the potential utility of δ13C as a tracer of energy pathways. This study serves as a robust test of isotopic quantification of food chain structure, and given global estimates of aquatic food chains approximate four trophic levels while many food chains include invertebrates, our use of four trophic level plant-invertebrate food chains makes our findings relevant for a majority of ecological systems

  4. Calcification rate and the stable carbon, oxygen, and nitrogen isotopes in the skeleton, host tissue, and zooxanthellae of bleached and recovering Hawaiian corals

    NASA Astrophysics Data System (ADS)

    Rodrigues, Lisa J.; Grottoli, Andréa G.

    2006-06-01

    We tested the effectiveness of stable isotopes as recorders of physiological changes that occur during coral bleaching and recovery. Montipora capitata and Porites compressa fragments were bleached in outdoor tanks with seawater temperature raised to 30 °C (treatment corals) for one month. Additional fragments were maintained at 27 °C in separate tanks (control corals). After one month, (0 months recovery), buoyant weight was measured and a subset of fragments was frozen. Remaining fragments were returned to the reef for recovery. After 1.5, 4, and 8 months, fragments were collected, measured for buoyant weight, and frozen. Fragments were analyzed for stable carbon and oxygen isotopic compositions of the skeleton (δ 13C s; δ 18O s) and nitrogen and carbon isotopic compositions of the host tissue (δ 15N h; δ 13C h) and zooxanthellae (δ 15N z; δ 13C z). δ 13C s decreased immediately after bleaching in M. capitata, but not in P. compressa. δ 18O s of both species failed to record the warming event. During the remaining months of recovery, δ 13C s and δ 18O s were more enriched in treatment than control corals due to decreases in calcification and metabolic fractionation during that time. Increased δ 15N h of treatment P. compressa may be due to expelled zooxanthellae during bleaching and recovery. Increased δ 15N z at 1.5 months in treatment fragments of both species reflects the increased incorporation of dissolved inorganic nitrogen to facilitate mitotic cell division and/or chl a/cell recovery. Changes in δ 13C h and δ 13C z at 1.5 months in treatment M. capitata indicated a large increase in heterotrophically acquired carbon relative to photosynthetically fixed carbon. We experimentally show that isotopes in coral skeleton, host tissue and zooxanthellae can be used to verify physiological changes during bleaching and recovery, but their use as a proxy for past bleaching events in the skeletal record is limited.

  5. THE DEVELOPMENT OF A PREDICTIVE TOLL USING LARGEMOUTH BASS (MICROPTERUS SALMOIDES) SCALES TO ESTIMATE MERCURY (HG) CONCENTRATIONS AND STABLE-NITROGEN (15N/14N) ISOTOPE RATIOS IN FISH MUSCLE TISSUE

    EPA Science Inventory

    Knowledge of the trophic structure of biota in aquatic sites offers potential for the construction of models to allow the prediction of contaminant bioaccumulation. Measurements of trophic position have been conducted using stable-nitrogen isotope ratios ( 15N) measured in fish m...

  6. Infant and child diet in Neolithic hunter-fisher-gatherers from Cis-Baikal, Siberia: intra-long bone stable nitrogen and carbon isotope ratios.

    PubMed

    Waters-Rist, Andrea L; Bazaliiskii, Vladimir I; Weber, Andrzej W; Katzenberg, M Anne

    2011-10-01

    Analysis of stable nitrogen and carbon isotopes (δ(15) N and δ(13) C) from subadults and adults allows for assessment of age-related dietary changes, including breastfeeding and weaning, and adoption of an adult diet. In one of the first studies of hunter-fisher-gatherer subadults from Eurasia, three Neolithic (8,800-5,200 calBP) mortuary sites from southwestern Siberia are analyzed to evaluate hypothesized differences in weaning age between Early versus Late Neolithic groups. An intra-individual sampling methodology is used to compare bone formed at different ages. Collagen samples (n = 143) from three different growth areas of long bones-the proximal metaphysis, diaphysis, and distal metaphysis-were obtained from 49 subadults aged birth to 10 years. In infants (birth to 3 years, n = 23) contrasting the δ(15) N values of the metaphysis, which contains newer bone, to the δ(15) N values of the diaphysis, which contains older bone, permits a more precise determination of breastfeeding-weaning status. In Early and Late Neolithic groups breast milk was the major protein source until the age of 2-3 years. However, there are differences in the age of weaning completion and duration: Early Neolithic groups weaned their infants at a later age and over a shorter amount of time. Differences may have affected infant morbidity and mortality, and female fecundity and inter-birth intervals. Stable isotope values in older subadults (4-10 years, n = 26) do not differ from adults suggesting the absence of age-based food allocation. Copyright © 2011 Wiley-Liss, Inc.

  7. Isotopes Will Let the Cat Out of the Bag: A Carbon and Nitrogen Stable Isotopic Analysis of Dry Cat Food Brands

    NASA Astrophysics Data System (ADS)

    Zelanko, P. M.

    2011-12-01

    There are a plethora of healthy cat food brands that make a wide variety of claims about the nutrition of their product and the lack of nutrition of their competitors. The claims range from "No sugar or corn" to "Real meat is always the 1st ingredient". The two major disagreements in the cat food market are the nutritional value of corn and the realness of meat products. Here I present a carbon and nitrogen stable isotopic analysis of a wide range of dry cat food brands. The beginning assumption was brands with claims of no corn would be depleted in δ13C compared to brands with corn and brands with real meat as the 1st ingredient would be enriched in δ 15N compared to brands with meat as a lesser ingredient. Preliminary results show brands with no corn (δ13C ~ -22%) are depleted compared to brands with corn (δ13C ~ -17%), which is to be expected. However, brands that claim real meat is the 1st ingredient are slightly depleted (δ15N ~ 3.5%) compared to brands with proportionally less meat (δ15N ~ 5%); the opposite of what was anticipated. Also, the stable isotopes of three house cats, that were all fed the same dry diet (corn as major ingredient), were tracked over time as they were switched to a diet with no corn. Variation was present in the first round of analysis and persisted throughout the dietary change, suggesting individual cats may absorb nutrients from the identical diets differently.

  8. Poultry offal meal in chicken: traceability using the technique of carbon (13C/12C)- and nitrogen (15N/14N)-stable isotopes.

    PubMed

    Cruz, V C; Araújo, P C; Sartori, J R; Pezzato, A C; Denadai, J C; Polycarpo, G V; Zanetti, L H; Ducatti, C

    2012-02-01

    Studies on the detection of animal by-products in poultry meat are rare and practically nonexistent in chicken meat. With the development of the technique of stable isotopes for traceability purposes and the certification of broiler diet patterns, it has been necessary to know the behavior of the isotopic signature of different tissues in birds, in case of a potential replacement of a diet containing animal ingredients with a strictly vegetable one and vice versa. Thus, this study, carried out at the São Paulo State University, Botucatu Campus, Brazil, aimed to evaluate meat from the breast, thigh, drumstick, and wings to trace the presence of poultry offal meal (OM) in broiler feed using the analysis of stable isotopes of carbon ((13)C/(12)C) and nitrogen ((15)N/(14)N) by mass spectrometry. In total, 720 one-d-old chicks were distributed into 6 groups: vegetable diet (VD) from 1 to 42 d; 8% poultry offal meal (OM) diet from 1 to 42 d; VD from 1 to 21 d and 8% OM diet from 22 to 42 d; VD from 1 to 35 d and 8% OM diet from 36 to 42 d; 8% OM diet from 1 to 21 d and VD from 22 to 42 d; and 8% OM diet from 1 to 35 d and VD from 36 to 42 d. Through the analysis of C and N, it is possible to trace the use of OM in broiler feeding when this ingredient is part of the feeding throughout the breeding phase or when it substitutes a strictly VD even up to 35 d. When an OM diet is substituted by a VD, the animal ingredient has to be part of the feeding for 21 d or longer to be detected by this method.

  9. Pacific sleeper shark Somniosus pacificus trophic ecology in the eastern North Pacific Ocean inferred from nitrogen and carbon stable-isotope ratios and diet.

    PubMed

    Courtney, D L; Foy, R

    2012-04-01

    Stable-isotope ratios of nitrogen (δ¹⁵N) and lipid-normalized carbon (δ¹³C') were used to examine geographic and ontogenetic variability in the trophic ecology of a high latitude benthopelagic elasmobranch, the Pacific sleeper shark Somniosus pacificus. Mean muscle tissue δ¹³C' values of S. pacificus differed significantly among geographic regions of the eastern North Pacific Ocean. Linear models identified significant ontogenetic and geographic variability in muscle tissue δ¹⁵N values of S. pacificus. The trophic position of S. pacificus in the eastern North Pacific Ocean estimated here from previously published stomach-content data (4·3) was within the range of S. pacificus trophic position predicted from a linear model of S. pacificus muscle tissue δ¹⁵N (3·3-5·7) for fish of the same mean total length (L(T) ; 201·5 cm), but uncertainty in predicted trophic position was very high (95% prediction intervals ranged from 2·9 to 6·4). The relative trophic position of S. pacificus determined here from a literature review of δ¹⁵N by taxa in the eastern North Pacific Ocean was also lower than would be expected based on stomach-content data alone when compared to fishes, squid and filter feeding whales. Stable-isotope analysis revealed wider variability in the feeding ecology of S. pacificus in the eastern North Pacific Ocean than shown by diet data alone, and expanded previous conclusions drawn from analyses of stomach-content data to regional and temporal scales meaningful for fisheries management.

  10. Environmental variables across Pan troglodytes study sites correspond with the carbon, but not the nitrogen, stable isotope ratios of chimpanzee hair.

    PubMed

    Schoeninger, Margaret J; Most, Corinna A; Moore, Jim J; Somerville, Andrew D

    2016-10-01

    Diet influences the stable isotope ratios of carbon and nitrogen (δ(13) C and δ(15) N values) in animal tissue; but here we explore the influences of particular aspects of the local environment on those values in chimpanzees (Pan troglodytes). In this article we present new δ(13) C and δ(15) N values in Gombe chimpanzees using hairs collected from night nests in 1989. Then, we explore the influence of environmental factors by comparing our Gombe data to those from eight additional Pan study sites with previously published stable isotope data. We compare chimpanzee δ(13) Chair and δ(15) Nhar values to specific characteristics of local site ecology (biome and ecoregion) and to local Mean Annual Precipitation (MAP) to test hypotheses based on known effects of these variables on the δ(13) C and δ(15) N values in plant tissues. The comparison shows that hair from chimpanzees living in savanna sites with lower MAP have higher δ(13) Chair values than do chimpanzees living in woodland and forested sites with higher MAP. These results demonstrate the potential of using δ(13) C values in primate tissue to indicate aspects of their local ecology in cases where the ecology is uncertain, such as samples collected early in the last century and in fossil hominins. In contrast to expectations, however, chimpanzee δ(15) Nhair values from some savanna sites with lower MAP are lower, not higher, than those living in more forested areas with higher MAP. It is likely that diet selectivity by chimpanzees affects δ(15) Nhair values to a greater extent than does the influence of precipitation on plants. Am. J. Primatol. 78:1055-1069, 2016. © 2015 Wiley Periodicals, Inc. © 2015 Wiley Periodicals, Inc.

  11. Host-dependent differences in resource use associated with Anilocra spp. parasitism in two coral reef fishes, as revealed by stable carbon and nitrogen isotope analyses

    USGS Publications Warehouse

    Welicky, Rachel; Demopoulos, Amanda W. J.; Sikkel, Paul C.

    2017-01-01

    The role of parasites in trophic ecology is poorly understood in marine ecosystems. Stable isotope analyses (SIA) have been widely used in studies of trophic ecology, but have rarely been applied to study the role of parasites. Considering that some parasites are associated with altered host foraging patterns, SIA can help elucidate whether parasitism influences host trophic interactions. French grunt (Haemulon flavolineatum), an abundant Caribbean coral reef fish, contributes greatly to trophic connectivity. They typically depart the reef at dusk, feed overnight in seagrass beds, and return to the reef at dawn. The large parasitic isopod Anilocra haemuli commonly infects French grunt, and infected fish are less likely to complete their diel migration, and are in poorer condition than uninfected conspecifics. Brown chromis (Chromis multilineata) are diurnally feeding planktivores and infection by Anilocra chromis does not influence host condition. To determine if Anilocra infection influences host diet and foraging locality, we conducted stable carbon and nitrogen isotope analyses on scale, muscle, heart and gill tissues of infected and uninfected French grunt and brown chromis. We determined that all French grunt had δ13C values representative of seagrass habitats, but infected French grunt were significantly enriched in 13C and 15N compared to uninfected conspecifics. This suggests that compared to uninfected conspecifics, infected French grunt forage in seagrass, but on isotopically enriched prey, and/or are in poorer condition, which can elevate δ13C and δ15N values. For brown chromis, infection did not significantly influence any δ13C and δ15N values; hence they all foraged in the same environment and on similar prey. This is the first study to use SIA to examine differences in resource use by Caribbean coral reef fishes associated with parasitism and to evaluate how closely related parasites might have host-dependent effects on host trophic ecology.

  12. Identification of a Thiomicrospira denitrificans-Like Epsilonproteobacterium as a Catalyst for Autotrophic Denitrification in the Central Baltic Sea†

    PubMed Central

    Brettar, Ingrid; Labrenz, Matthias; Flavier, Sébastien; Bötel, Julia; Kuosa, Harri; Christen, Richard; Höfle, Manfred G.

    2006-01-01

    Identification and functional analysis of key members of bacterial communities in marine and estuarine environments are major challenges for obtaining a mechanistic understanding of biogeochemical processes. In the Baltic Sea basins, as in many other marine environments with anoxic bodies of water, the oxic-anoxic interface is considered a layer of high bacterial turnover of sulfur, nitrogen, and carbon compounds that has a great impact on matter balances in the whole ecosystem. We focused on autotrophic denitrification by oxidation of reduced sulfur compounds as a biogeochemically important process mediating concomitant turnover of sulfur, nitrogen, and carbon. We used a newly developed approach consisting of molecular analyses in stimulation experiments and in situ abundance. The molecular approach was based on single-strand conformational polymorphism (SSCP) analysis of the bacterial community RNA, which allowed identification of potential denitrifiers based on the sequences of enhanced SSCP bands and monitoring of the overall bacterial community during the experiments. Sequences of the SSCP bands of interest were used to design highly specific primers that enabled (i) generation of almost complete 16S rRNA gene sequences using experimental and environmental DNA as templates and (ii) quantification of the bacteria of interest by real-time PCR. By using this approach we identified the bacteria responsible for autotrophic denitrification as a single taxon, an epsilonproteobacterium related to the autotrophic denitrifier Thiomicrospira denitrificans. This finding was confirmed by material balances in the experiments that were consistent with those obtained with continuous cultures of T. denitrificans. The presence and activity of a bacterium that is phylogenetically and physiologically closely related to T. denitrificans could be relevant for the carbon budget of the central Baltic Sea because T. denitrificans exhibits only one-half the efficiency for carbon

  13. Vertical distribution of vibrational energy of molecular nitrogen in a stable auroral red arc and its effect on ionospheric electron densities. Ph.D. Thesis - Catholic Univ. of Am.

    NASA Technical Reports Server (NTRS)

    Newton, G. P.

    1973-01-01

    Previous solutions of the problem of the distribution of vibrationally excited molecular nitrogen in the thermosphere have either assumed a Boltzmann distribution and considered diffusion as one of the loss processes or solved for the energy level populations and neglected diffusion. Both of the previous approaches are combined by solving the time dependent continuity equations, including the diffusion process, for the first six energy levels of molecular nitrogen for conditions in the thermosphere corresponding to a stable auroral red arc. The primary source of molecular nitrogen excitation was subexcitation, and inelastic collisions between thermal electrons and molecular nitrogen. The reaction rates for this process were calculated from published cross section calculations. The loss processes for vibrational energy were electron and atomic oxygen quenching and vibrational energy exchange. The coupled sets of nonlinear, partial differential equations were solved numerically by employing finite difference equations.

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

    USGS Publications Warehouse

    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. Pan-Arctic concentrations of mercury and stable isotope ratios of carbon (δ(13)C) and nitrogen (δ(15)N) in marine zooplankton.

    PubMed

    Pomerleau, Corinne; Stern, Gary A; Pućko, Monika; Foster, Karen L; Macdonald, Robie W; Fortier, Louis

    2016-05-01

    Zooplankton play a central role in marine food webs, dictating the quantity and quality of energy available to upper trophic levels. They act as "keystone" species in transfer of mercury (Hg) up through the marine food chain. Here, we present the first Pan-Arctic overview of total and monomethylmercury concentrations (THg and MMHg) and stable isotope ratios of carbon (δ(13)C) and nitrogen (δ(15)N) in selected zooplankton species by assembling data collected between 1998 and 2012 from six arctic regions (Laptev Sea, Chukchi Sea, southeastern Beaufort Sea, Canadian Arctic Archipelago, Hudson Bay and northern Baffin Bay). MMHg concentrations in Calanus spp., Themisto spp. and Paraeuchaeta spp. were found to increase with higher δ(15)N and lower δ(13)C. The southern Beaufort Sea exhibited both the highest THg and MMHg concentrations. Biomagnification of MMHg between Calanus spp. and two of its known predators, Themisto spp. and Paraeuchaeta spp., was greatest in the southern Beaufort Sea. Our results show large geographical variations in Hg concentrations and isotopic signatures for individual species related to regional ecosystem features, such as varying water masses and freshwater inputs, and highlight the increased exposure to Hg in the marine food chain of the southern Beaufort Sea. Copyright © 2016 Elsevier B.V. All rights reserved.

  16. Carbon and nitrogen composition and stable isotope as potential indicators of source and fate of organic matter in the salt marsh of the Changjiang Estuary, China.

    PubMed

    Zhou, Junli; Wu, Ying; Zhang, Jing; Kang, Qinshu; Liu, Zhengtao

    2006-10-01

    Elemental (TOC, TN, C/N) and stable carbon and nitrogen isotopic (delta(13)C, delta(15)N) compositions were measured for surface sediments, three sediment vibrocores, plants, and suspended particulate matter (SPM) collected from salt marsh of the Changjiang Estuary. The purpose of this study is to characterize the sources of organic matter in sediments and to further elucidate the factors influencing the isotope signature in the salt marsh. Our results indicate that organic matter preserved in the sediments is predominantly controlled by the particulate organic matter in the Changjiang Estuary. The in situ contribution of marsh plants carbon to sediment organic matter is clearest in the high marsh, where the low delta(13)C of the plants (-28.1 per thousand) is reflected by a sediment delta(13)C (-24.7 per thousand) lower than values found for the low marsh and bare flat sediments (-23.4 per thousand and -23.0 per thousand, respectively). The effect of grain size on the spatial difference of isotope composition in the marsh sediments is insignificant, based on the observation that similar isotope values are found in different size particles, both for delta(13)C and delta(15)N. Nutrient utilization by plant assimilation, however, shows great impact on the surface sediment delta(15)N composition, due to the isotope fractionation. With extensive plant coverage and the consequent low surface water nitrate concentration, delta(15)N values of the high marsh surface sediments show (15)N enrichment.

  17. Ammonium removal by the oxygen-limited autotrophic nitrification-denitrification system

    SciTech Connect

    Kuai, L.; Verstraete, W.

    1998-11-01

    The present lab-scale research reveals the potential of implementation of an oxygen-limited autotrophic nitrification-denitrification (OLAND) system with normal nitrifying sludge as the biocatalyst for the removal of nitrogen from nitrogen-rich wastewater in one step. In a sequential batch reactor, synthetic wastewater containing 1 g of NH{sub 4}{sup +}-N liter{sup {minus}1} and minerals was treated. Oxygen supply to the reactor was double-controlled with a pH controller and a timer. At a volumetric loading rate (B{sub {nu}}) of 0.13 g of NH{sub 4}{sup +}-N liter{sup {minus}1} day{sup {minus}1}, about 22% of the fed NH{sub 4}{sup +}-N was converted to NO{sub 2}{sup {minus}}-N, 38% remained as NH{sub 4}{sup +}-N, and the other 40% was removed mainly as N{sub 2}. The specific removal rate of nitrogen was on the order of 50 mg of N liter{sup {minus}1} day{sup {minus}1}, corresponding to 16 mg of N g of volatile suspended solids{sup {minus}1} day{sup {minus}1}. The microorganisms which catalyzed the OLAND process are assumed to be normal nitrifiers dominated by ammonium oxidizers. The loss of nitrogen in the OLAND system is presumed to occur via the oxidation of NH{sub 4}{sup +} to N{sub 2} with NO{sub 2}{sup {minus}} as the electron acceptor. Hydroxylamine stimulated the removal of NH{sub 4}{sup +} and NO{sub 2}{sup {minus}}. Hydroxylamine oxidoreductase (HAO) or an HAO-related enzyme might be responsible for the loss of nitrogen.

  18. Carbon and Energy Sources for the Nitrifying Autotroph Nitrobacter

    PubMed Central

    Delwiche, C. C.; Finstein, M. S.

    1965-01-01

    Delwiche, C. C. (University of California, Davis), and M. S. Finstein. Carbon and energy sources for the nitrifying autotroph Nitrobacter. J. Bacteriol. 90:102–107. 1965.—The effect of various organic compounds on the growth and metabolism of the obligatively autotrophic nitrifying organism Nitrobacter was studied. A slight stimulation of both nitrification and growth was obtainable with a number of organic amendments, including yeast extract, Vitamin Free Casamino Acids, and some amino acids. Depending upon culture conditions, a strong stimulation of growth was obtained with acetate as an amendment to the culture solution. Several compounds, including valine, hydroxyproline, and threonine, were inhibitory at concentrations of 10−3m. The incorporation of carbon from isotopically labeled organic compounds was demonstrated. Acetate and glycine were particularly strong contributors to cell carbons. These could not substitute for carbon dioxide as a sole carbon source for growth, however, nor could any other of the carbon compounds that were tried. PMID:16562002

  19. Autotrophic biorefinery: dawn of the gaseous carbon feedstock.

    PubMed

    Butti, Sai Kishore; Mohan, S Venkata

    2017-10-02

    CO2 is a resource yet to be effectively utilized in the autotrophic biotechnology, not only to mitigate and moderate the anthropogenic influence on our climate, but also to steer CO2 sequestration for sustainable development and carbon neutral status. The atmospheric CO2 concentration has seen an exponential increase with the turn of the new millennia causing numerous environmental issues and also in a way feedstock crisis. To progressively regulate the growing CO2 concentrations and to incorporate the integration strategies to our existing CO2 capturing tools, all the influencing factors need to be collectively considered. The review article puts forth the change in perception of CO2 from which was once considered a harmful pollutant having deleterious effects to a renewable carbon source bearing the potential to replace the fossils as the carbon source through an autotrophic biorefinery. Here, we review the current methods employed for CO2 storage and capture, the need to develop sustainable methods and the ways of improving the sequestration efficiencies by various novice technologies. The review also provides an autotrophic biorefinery model with the potential to operate and produces a multitude of biobased products analogous to the petroleum refinery to establish a circular bioeconomy. Furthermore, fundamental and applied research niches that merit further research are delineated. © FEMS 2017. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

  20. Nitrate removal with lateral flow sulphur autotrophic denitrification reactor.

    PubMed

    Lv, Xiaomei; Shao, Mingfei; Li, Ji; Xie, Chuanbo

    2014-01-01

    An innovative lateral flow sulphur autotrophic denitrification (LFSAD) reactor was developed in this study; the treatment performance was evaluated and compared with traditional sulphur/limestone autotrophic denitrification (SLAD) reactor. Results showed that nitrite accumulation in the LFSAD reactor was less than 1.0 mg/L during the whole operation. Denitrification rate increased with the increased initial alkalinity and was approaching saturation when initial alkalinity exceeded 2.5 times the theoretical value. Higher influent nitrate concentration could facilitate nitrate removal capacity. In addition, denitrification efficiency could be promoted under an appropriate reflux ratio, and the highest nitrate removal percentage was achieved under reflux ratio of 200%, increased by 23.8% than that without reflux. Running resistance was only about 1/9 of that in SLAD reactor with equal amount of nitrate removed, which was the prominent excellence of the new reactor. In short, this study indicated that the developed reactor was feasible for nitrate removal from waters with lower concentrations, including contaminated surface water, groundwater or secondary effluent of municipal wastewater treatment with fairly low running resistance. The innovation in reactor design in this study may bring forth new ideas of reactor development of sulphur autotrophic denitrification for nitrate-contaminated water treatment.

  1. Modelling autotrophic and heterotrophic components of soil respiration in wheat fields

    NASA Astrophysics Data System (ADS)

    Delogu, E.; LeDantec, V.; Buysse, P.; Mordelet, P.; Aubinet, M.

    2012-04-01

    Partitioning soil respiration into its heterotrophic and autotrophic components is a current key challenge to improve understanding of soil processes in croplands. For this purpose, we coupled a daily-time step soil organic carbon model derived from the CENTURY (Parton et al, 1987) calculating carbon turnover and carbon dioxide production in the soil with root sub-model from the plant process-based model CASTANEA (Dufrêne et al, 2005). In the Century model, soil organic carbon is divided into three major components including active, slow and passive soil carbon. Each pool has its own decomposition constant. Carbon flows between these pools are controlled by carbon inputs (crop residue), decomposition rate and microbial respiration loss parameters, both of which are a function of soil texture, soil temperature and soil water content. The model assumes that all C decompositions flows are associated with microbial activity and that microbial respiration occurs for each of these flows. Heterotrophic soil respiration is the sum of all these microbial respiration processes. To simulate autotrophic component, maintenance respiration is calculated from the nitrogen content and assuming an exponential relationship to account for temperature dependence. Growth respiration is calculated assuming that daily growth respiration depends on both growth rate and construction cost of the considered organ. To investigate model performances, simulations of soil CO2 efflux were compared with 3 datasets recorded in three different fields under different soil and climate conditions. Soil respiration measurements were performed on three winter wheat crops on Lamasquère (2007) and Auradé (2008), South-West France and in Lonzée (2007), Belgium. The French sites data come from manual measurement chambers, PP systems. The Belgium site is equipped with an automatic (half-hour resolution time) measurement system. The model was run on the three climatic years of data on bare soil and a first

  2. Sedimentary organic matter in two Spitsbergen fjords: Terrestrial and marine contributions based on carbon and nitrogen contents and stable isotopes composition

    NASA Astrophysics Data System (ADS)

    Koziorowska, Katarzyna; Kuliński, Karol; Pempkowiak, Janusz

    2016-02-01

    The aim of this study was to estimate the spatial variability of organic carbon (Corg) and total nitrogen (Ntot) concentrations, Corg/Ntot ratios, stable isotopes of carbon and nitrogen (δ13Corg, δ15Ntot) and the proportions of autochthonous and allochtonous organic matter within recently deposited sediments of two Spitsbergen fjords: the Hornsund and the Adventfjord, which are affected to a different degree by the West Spitsbergen Current. Corg concentrations ranged from 1.38% to 1.98% in the Hornsund and from 1.73% to 3.85% in the Adventfjord. In both fjords the highest Corg concentrations were measured at the innermost stations and they decreased towards the mouths of the fjords. This suggests fresh water runoff to be an important source of organic matter (OM) for surface sediments. The results showed that both fjords differ significantly in terms of sedimentary organic matter characteristics. The samples from the Hornsund, except those from the innermost station in the Brepollen, had relatively low Corg/Ntot ratios, all within a narrow range (from 9.7 to 11.3). On the other hand significantly higher Corg/Ntot ratios, varying within a broad range (from 14.6 to 33.0), were measured in the Adventfjord. The samples from the Hornsund were characterized by higher δ13Corg (from -24.90‰ to -23.87‰) and δ15Ntot (from 3.02‰ to 4.93‰) than those from the Adventfjord (-25.94‰ to -24.69‰ and from 0.71‰ to 4.00‰, respectively). This is attributed to a larger proportion of marine organic matter. Using the two end-member approach proportions of terrestrial organic matter were evaluated. Terrestrial OM contribution for the Adventfjord was in the range of 82-83%, while in case of the Hornsund the results were in the range of 69-75%, with the exception of the innermost part of the fjord, where terrestrial organic matter contribution ranged from 80 to 82%. The strong positive correlation between δ13Corg and δ15Ntot was revealed. This was taken as an indicator

  3. Combining stable isotopes with contamination indicators: A method for improved investigation of nitrate sources and dynamics in aquifers with mixed nitrogen inputs.

    PubMed

    Minet, E P; Goodhue, R; Meier-Augenstein, W; Kalin, R M; Fenton, O; Richards, K G; Coxon, C E

    2017-11-01

    Excessive nitrate (NO3(-)) concentration in groundwater raises health and environmental issues that must be addressed by all European Union (EU) member states under the Nitrates Directive and the Water Framework Directive. The identification of NO3(-) sources is critical to efficiently control or reverse NO3(-) contamination that affects many aquifers. In that respect, the use of stable isotope ratios (15)N/(14)N and (18)O/(16)O in NO3(-) (expressed as δ(15)N-NO3(-) and δ(18)O-NO3(-), respectively) has long shown its value. However, limitations exist in complex environments where multiple nitrogen (N) sources coexist. This two-year study explores a method for improved NO3(-) source investigation in a shallow unconfined aquifer with mixed N inputs and a long established NO3(-) problem. In this tillage-dominated area of free-draining soil and subsoil, suspected NO3(-) sources were diffuse applications of artificial fertiliser and organic point sources (septic tanks and farmyards). Bearing in mind that artificial diffuse sources were ubiquitous, groundwater samples were first classified according to a combination of two indicators relevant of point source contamination: presence/absence of organic point sources (i.e. septic tank and/or farmyard) near sampling wells and exceedance/non-exceedance of a contamination threshold value for sodium (Na(+)) in groundwater. This classification identified three contamination groups: agricultural diffuse source but no point source (D+P-), agricultural diffuse and point source (D+P+) and agricultural diffuse but point source occurrence ambiguous (D+P±). Thereafter δ(15)N-NO3(-) and δ(18)O-NO3(-) data were superimposed on the classification. As δ(15)N-NO3(-) was plotted against δ(18)O-NO3(-), comparisons were made between the different contamination groups. Overall, both δ variables were significantly and positively correlated (p < 0.0001, rs = 0.599, slope of 0.5), which was indicative of denitrification. An inspection

  4. Nitrous oxide emission in autotrophic partial nitritation system: Macro- and microanalyses.

    PubMed

    Ju, Kai; Wang, Lei; Lv, Yongtao; Zhang, Xueling; Miao, Rui; Wang, Xudong

    2015-10-01

    A laboratory-scale sequencing batch reactor fed with synthetic high-ammonium wastewater was operated for autotrophic partial nitritation, and the characteristics of N2O emission were investigated by both macro- and microanalysis. A N2O emission quantity of 5.98 ± 1.24 mg (n = 17) was observed, accounting for 0.997% ± 0.408% of the influent nitrogen. The N2O level in the off-gas first increased to a maximum of 91.5 ppmv in the initial 50 min, and then decreased and remained around 34.8 ppmv until the end of aeration. An asymptotic function (y = 14.3-14.2 × 0.992(x), R(2) = 0.997) could be used to estimate the quantity of N2O emitted. Microelectrodes were used to explore the variations in the nitrogen distribution and consumption rate within sludge flocs as the reaction proceeded. During the aeration phase, partial nitritation occurred mainly in the surface layer of flocs. This is where most N2O was produced, indicating that N2O was generated as a byproduct of the nitritation. During the settling phase, the N2O concentration and volumetric production rate were much higher than those in the aeration phase, suggesting that the settling phase contributes to the initial N2O emission peak.

  5. Low temperature, autotrophic microbial denitrification using thiosulfate or thiocyanate as electron donor.

    PubMed

    Broman, Elias; Jawad, Abbtesaim; Wu, Xiaofen; Christel, Stephan; Ni, Gaofeng; Lopez-Fernandez, Margarita; Sundkvist, Jan-Eric; Dopson, Mark

    2017-08-01

    Wastewaters generated during mining and processing of metal sulfide ores are often acidic (pH < 3) and can contain significant concentrations of nitrate, nitrite, and ammonium from nitrogen based explosives. In addition, wastewaters from sulfide ore treatment plants and tailings ponds typically contain large amounts of inorganic sulfur compounds, such as thiosulfate and tetrathionate. Release of these wastewaters can lead to environmental acidification as well as an increase in nutrients (eutrophication) and compounds that are potentially toxic to humans and animals. Waters from cyanidation plants for gold extraction will often conjointly include toxic, sulfur containing thiocyanate. More stringent regulatory limits on the release of mining wastes containing compounds such as inorganic sulfur compounds, nitrate, and thiocyanate, along the need to increase production from sulfide mineral mining calls for low cost techniques to remove these pollutants under ambient temperatures (approximately 8 °C). In this study, we used both aerobic and anaerobic continuous cultures to successfully couple inorganic sulfur compound (i.e. thiosulfate and thiocyanate) oxidation for the removal of nitrogenous compounds under neutral to acidic pH at the low temperatures typical for boreal climates. Furthermore, the development of the respective microbial communities was identified over time by DNA sequencing, and found to contain a consortium including populations aligning within Flavobacterium, Thiobacillus, and Comamonadaceae lineages. This is the first study to remediate mining waste waters by coupling autotrophic thiocyanate oxidation to nitrate reduction at low temperatures and acidic pH by means of an identified microbial community.

  6. Diurnal variations of carbonaceous components, major ions, and stable carbon and nitrogen isotope ratios in suburban aerosols from northern vicinity of Beijing

    NASA Astrophysics Data System (ADS)

    He, Nannan; Kawamura, Kimitaka; Kanaya, Yugo; Wang, Zifa

    2015-12-01

    We report diurnal variations of organic carbon (OC), elemental carbon (EC), water-soluble organic carbon (WSOC) and major ions as well as stable carbon and nitrogen isotope ratios (δ13C and δ15N) in ambient aerosols at a suburban site (Mangshan), 40 km north of Beijing, China. We found that aerosol chemical compositions were largely controlled by the air mass transport from Beijing in daytime with southerly winds and by relatively fresh air mass in nighttime from the northern forest areas with northerly winds. Higher concentrations of aerosol mass and total carbon were obtained in daytime. Further, higher OC/EC ratios were recorded in daytime (4.0 ± 1.7) than nighttime (3.2 ± 0.7), suggesting that OC is formed by photochemical oxidation of gaseous precursors in daytime. Contributions of WSOC to OC were slightly higher in daytime (38%) than nighttime (34%), possibly due to secondary formation of WSOC in daytime. We also found higher concentrations of Ca2+ in daytime, which was originated from the construction dust in Beijing area and transported to the sampling site. δ13C ranged from -25.3 to -21.2‰ (ave. -23.5 ± 0.9‰) in daytime and -29.0 to -21.4‰ (-24.0 ± 1.5‰) in nighttime, suggesting that Mangshan aerosols were more influenced by fossil fuel combustion products in daytime and by terrestrial C3 plants in nighttime. This study suggests that daytime air mass delivery from megacity Beijing largely influence the air quality at the receptor site in the north together with photochemical processing of organic aerosols during the atmospheric transport, whereas the Mangshan site is covered with relatively clean air masses at night.

  7. Sediment source detection by stable isotope analysis, carbon and nitrogen content and CSSI in a small river of the Swiss Plateau

    NASA Astrophysics Data System (ADS)

    SchindlerWildhaber, Yael; Alewell, Christine; Birkholz, Axel

    2014-05-01

    Suspended sediment (SS) and organic matter in rivers can harm the fauna by affecting health and fitness of free swimming fish and by causing siltation of the riverbed. The temporal and spatial dynamics of sediment, carbon (C) and nitrogen (N) during the brown trout spawning season in a small river of the Swiss Plateau were assessed and C isotopes as well as the C/N atomic ratio were used to distinguish autochthonous and allochthonous sources of organic matter in SS loads. The visual basic program IsoSource with 13Ctot and 15N as input isotopes was used to quantify the temporal and spatial sources of SS. We determined compound specific stable carbon isotopes (CSSI) in fatty acids of possible sediment source areas to the stream in addition and compared them to SS from selected high flow and low flow events. Organic matter concentrations in the infiltrated and suspended sediment were highest during low flow periods with small sediment loads and lowest during high flow periods with high sediment loads. Peak values in nitrate and dissolved organic C were measured during high flow and high rainfall, probably due to leaching from pasture and arable land. The organic matter was of allochthonous sources as indicated by the C/N atomic ratio and δ13Corg. Organic matter in SS increased from up- to downstream due to an increase in sediment delivery from pasture and arable land downstream of the river. While the major sources of SS are pasture and arable land during base flow conditions, SS from forest soils increased during heavy rain events and warmer winter periods most likely due to snow melt which triggered erosion. Preliminary results of CSSI analysis of sediment source areas and comparison to SS of selected events indicate that differences in d13C values of individual fatty acids are too small to differentiate unambiguously between sediment sources.

  8. Characterization of carbon and nitrogen stable isotope gradients in the northern Gulf of Alaska using terminal feed stage copepodite-V Neocalanus cristatus

    NASA Astrophysics Data System (ADS)

    Kline, Thomas C., Jr.

    2009-12-01

    Individual terminal-feeding copepodite-V stage Neocalanus cristatus were collected systematically in the northern Gulf of Alaska (GOA) near 60°N from 1998 to 2004 from which the natural abundance of stable carbon and nitrogen isotopes was measured. The data confirmed the existence of an isotopic cross-shelf gradient such that values low in 13C content are diagnostic of oceanic production from the GOA when measured in organisms taken from Prince William Sound (PWS). The mean 13C/ 12C cross-shelf gradient of 3-4 delta units was relatively strong, with generally good separation between GOA and Prince William Sound observations, whereas the mean 15N/ 14N gradient of ˜2 delta units was relatively weak, with frequent overlap between GOA and PWS observations. There was a seasonal 15N/ 14N increase in the GOA. The 13C/ 12C values observed in PWS were more consistent over time than those observed in the GOA. Distinctively high 13C/ 12C values that were similar to those typical of PWS were observed at the continental slope during three of the Mays in the 1998-2004 period. The circulation pattern associated with mesoscale eddies, when they occurred just south of the sampling line based on satellite sea-surface height anomaly data, suggested that cross-shelf flow in the offshore direction drove high slope 13C/ 12C values. These observations led to positing that high 13C/ 12C values reflect coastal carbon isotope signatures and diatom blooms. Based on samples from May 1996, the three GOA Neocalanus congeners had concordant isotopic patterns with relatively small systematic species differences confirming that the isotopic patterns observed for N. cristatus apply to other zooplankton.

  9. Pacific Ocean–Wide Profile of CYP1A1 Expression, Stable Carbon and Nitrogen Isotope Ratios, and Organic Contaminant Burden in Sperm Whale Skin Biopsies

    PubMed Central

    Godard-Codding, Céline A.J.; Clark, Rebecca; Fossi, Maria Cristina; Marsili, Letizia; Maltese, Silvia; West, Adam G.; Valenzuela, Luciano; Rowntree, Victoria; Polyak, Ildiko; Cannon, John C.; Pinkerton, Kim; Rubio-Cisneros, Nadia; Mesnick, Sarah L.; Cox, Stephen B.; Kerr, Iain; Payne, Roger; Stegeman, John J.

    2011-01-01

    Background Ocean pollution affects marine organisms and ecosystems as well as humans. The International Oceanographic Commission recommends ocean health monitoring programs to investigate the presence of marine contaminants and the health of threatened species and the use of multiple and early-warning biomarker approaches. Objective We explored the hypothesis that biomarker and contaminant analyses in skin biopsies of the threatened sperm whale (Physeter macrocephalus) could reveal geographical trends in exposure on an oceanwide scale. Methods We analyzed cytochrome P450 1A1 (CYP1A1) expression (by immunohistochemistry), stable nitrogen and carbon isotope ratios (as general indicators of trophic position and latitude, respectively), and contaminant burdens in skin biopsies to explore regional trends in the Pacific Ocean. Results Biomarker analyses revealed significant regional differences within the Pacific Ocean. CYP1A1 expression was highest in whales from the Galapagos, a United Nations Educational, Scientific, and Cultural Organization World Heritage marine reserve, and was lowest in the sampling sites farthest away from continents. We examined the possible influence of the whales’ sex, diet, or range and other parameters on regional variation in CYP1A1 expression, but data were inconclusive. In general, CYP1A1 expression was not significantly correlated with contaminant burdens in blubber. However, small sample sizes precluded detailed chemical analyses, and power to detect significant associations was limited. Conclusions Our large-scale monitoring study was successful at identifying regional differences in CYP1A1 expression, providing a baseline for this known biomarker of exposure to aryl hydrocarbon receptor agonists. However, we could not identify factors that explained this variation. Future oceanwide CYP1A1 expression profiles in cetacean skin biopsies are warranted and could reveal whether globally distributed chemicals occur at biochemically

  10. Pacific Ocean-wide profile of CYP1A1 expression, stable carbon and nitrogen isotope ratios, and organic contaminant burden in sperm whale skin biopsies.

    PubMed

    Godard-Codding, Céline A J; Clark, Rebecca; Fossi, Maria Cristina; Marsili, Letizia; Maltese, Silvia; West, Adam G; Valenzuela, Luciano; Rowntree, Victoria; Polyak, Ildiko; Cannon, John C; Pinkerton, Kim; Rubio-Cisneros, Nadia; Mesnick, Sarah L; Cox, Stephen B; Kerr, Iain; Payne, Roger; Stegeman, John J

    2011-03-01

    Ocean pollution affects marine organisms and ecosystems as well as humans. The International Oceanographic Commission recommends ocean health monitoring programs to investigate the presence of marine contaminants and the health of threatened species and the use of multiple and early-warning biomarker approaches. We explored the hypothesis that biomarker and contaminant analyses in skin biopsies of the threatened sperm whale (Physeter macrocephalus) could reveal geographical trends in exposure on an oceanwide scale. We analyzed cytochrome P450 1A1 (CYP1A1) expression (by immunohistochemistry), stable nitrogen and carbon isotope ratios (as general indicators of trophic position and latitude, respectively), and contaminant burdens in skin biopsies to explore regional trends in the Pacific Ocean. Biomarker analyses revealed significant regional differences within the Pacific Ocean. CYP1A1 expression was highest in whales from the Galapagos, a United Nations Educational, Scientific, and Cultural Organization World Heritage marine reserve, and was lowest in the sampling sites farthest away from continents. We examined the possible influence of the whales' sex, diet, or range and other parameters on regional variation in CYP1A1 expression, but data were inconclusive. In general, CYP1A1 expression was not significantly correlated with contaminant burdens in blubber. However, small sample sizes precluded detailed chemical analyses, and power to detect significant associations was limited. Our large-scale monitoring study was successful at identifying regional differences in CYP1A1 expression, providing a baseline for this known biomarker of exposure to aryl hydrocarbon receptor agonists. However, we could not identify factors that explained this variation. Future oceanwide CYP1A1 expression profiles in cetacean skin biopsies are warranted and could reveal whether globally distributed chemicals occur at biochemically relevant concentrations on a global basis, which may

  11. Quantifying sediment source contributions in coastal catchments impacted by the Fukushima nuclear accident with carbon and nitrogen elemental concentrations and stable isotope ratios

    NASA Astrophysics Data System (ADS)

    Laceby, J. Patrick; Huon Huon, Sylvain; Onda, Yuichi; Evrard, Olivier

    2016-04-01

    The Fukushima Dai-ichi Nuclear Power Plant accidental release of radioactive contaminants resulted in the significant fallout of radiocesium over several coastal catchments in the Fukushima Prefecture. Radiocesium, considered to be the greatest risk to the short and long term health of the local community, is rapidly bound to fine soil particles and thus is mobilized and transported during soil erosion and runoff processes. As there has been a broad-scale decontamination of rice paddy fields and rural residential areas in the contaminated region, one important long term question is whether there is, or may be, a downstream transfer of radiocesium from forests that covered over 65% of the most contaminated region. Accordingly, carbon and nitrogen elemental concentrations and stable isotope ratios are used to determine the relative contributions of forests and rice paddies to transported sediment in three contaminated coastal catchments. Samples were taken from the three main identified sources: cultivated soils (rice paddies and fields, n=30), forest soils (n=45), and subsoils (channel bank and decontaminated soils, n = 25). Lag deposit sediment samples were obtained from five sampling campaigns that targeted the main hydrological events from October 2011 to October 2014. In total, 86 samples of deposited sediment were analyzed for particulate organic matter elemental concentrations and isotope ratios, 24 from the Mano catchment, 44 from the Niida catchment, and 18 from the Ota catchment. Mann-Whitney U-tests were used to examine the source discrimination potential of this tracing suite and select the appropriate tracers for modelling. The discriminant tracers were modelled with a concentration-dependent distribution mixing model. Preliminary results indicate that cultivated sources (predominantly rice paddies) contribute disproportionately more sediment per unit area than forested regions in these contaminated catchments. Future research will examine if there are

  12. Membrane biofouling in a wastewater nitrification reactor: Microbial succession from autotrophic colonization to heterotrophic domination.

    PubMed

    Lu, Huijie; Xue, Zheng; Saikaly, Pascal; Nunes, Suzana P; Bluver, Ted R; Liu, Wen-Tso

    2016-01-01

    Membrane biofouling is a complex process that involves bacterial adhesion, extracellular polymeric substances (EPS) excretion and utilization, and species interactions. To obtain a better understanding of the microbial ecology of biofouling process, this study conducted rigorous, time-course analyses on the structure, EPS and microbial composition of the fouling layer developed on ultrafiltration membranes in a nitrification bioreactor. During a 14-day fouling event, three phases were determined according to the flux decline and microbial succession patterns. In Phase I (0-2 days), small sludge flocs in the bulk liquid were selectively attached on membrane surfaces, leading to the formation of similar EPS and microbial community composition as the early biofilms. Dominant populations in small flocs, e.g., Nitrosomonas, Nitrobacter, and Acinetobacter spp., were also the major initial colonizers on membranes. In Phase II (2-4 d), fouling layer structure, EPS composition, and bacterial community went through significant changes. Initial colonizers were replaced by fast-growing and metabolically versatile heterotrophs (e.g., unclassified Sphingobacteria). The declining EPS polysaccharide to protein (PS:PN) ratios could be correlated well with the increase in microbial community diversity. In Phase III (5-14 d), heterotrophs comprised over 90% of the community, whereas biofilm structure and EPS composition remained relatively stable. In all phases, AOB and NOB were constantly found within the top 40% of the fouling layer, with the maximum concentrations around 15% from the top. The overall microbial succession pattern from autotrophic colonization to heterotrophic domination implied that MBR biofouling could be alleviated by forming larger bacterial flocs in bioreactor suspension (reducing autotrophic colonization), and by designing more specific cleaning procedures targeting dominant heterotrophs during typical filtration cycles. Copyright © 2015 Elsevier Ltd. All

  13. Nitrogen Inputs via Nitrogen Fixation in Northern Plants and Soils

    NASA Astrophysics Data System (ADS)

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

    2015-12-01

    Dominated by cold and often acidic water logged environments, mineralization of organic matter is slow in the majority of northern ecosystems. Measures of extractable ammonium and nitrate are generally low and can be undetectable in peat pore waters. Despite this apparent nitrogen limitation, many of these environments produce deep deposits of soil organic matter. Biological nitrogen fixation carried out by autotrophic and heterotrophic diazotrophs associated with cryptograms provides the majority of known nitrogen inputs in these northern ecosystems. Nitrogen fixation was assessed in a variety of northern soils within rhizospheres of dominant plant communities. We investigated the availability of this newly fixed nitrogen to the vascular plant community in nitrogen limited northern plant communities. We tracked nitrogen flow from 15N2 gas fixed in Sphagnum mosses into tissues of two native vascular plant species, boreal cranberry (Vaccinium oxycoccus) and black spruce (Picea mariana). 15N-labeled Sphagnum microcosms were grown within variable mesh size exclusion/inclusion fabrics in a nitrogen addition experiment in situ in order to investigate the role of mycorrhizal fungi in the uptake of newly fixed nitrogen. Up to 24% of daily fixed 15N label was transferred to vascular plant tissues during 2 months. Nitrogen addition resulted in decreased N2 fixation rates; however, with higher nitrogen availability there was a higher rate of 15N label uptake into the vascular plants, likely the result of increased production of dissolved organic nitrogen. Reliance on mycorrhizal networks for nitrogen acquisition was indicated by nitrogen isotope fractionation patterns. Moreover, N2 fixation activities in mosses were stimulated when vascular plants were grown in moss microcosms versus "moss only" treatments. Results indicate that bog vascular plants may derive considerable nitrogen from atmospheric N2 biologically fixed within Sphagnum mosses. This work demonstrates that

  14. Nitrogen removal rates at a technical-scale pilot plant with the one-stage partial nitritation/Anammox process.

    PubMed

    Cema, G; Szatkowska, B; Plaza, E; Trela, J; Surmacz-Górska, J

    2006-01-01

    Traditional nitrification/denitrification is not suitable for nitrogen removal when wastewater contains high concentrations of ammonium nitrogen and low concentrations of biodegradable carbon. Recently, a deammonification process was developed and proposed as a new technology for treatment of such streams. This process relies on a stable interaction between aerobic bacteria Nitrosomonas, that accomplish partial nitritation and anaerobic bacteria Planctomycetales, which conduct the Anammox reaction. Simultaneous performance of these two processes can lead to a complete autotrophic nitrogen removal in one single reactor. The experiments where nitrogen was removed in one reactor were performed at a technical-scale moving-bed pilot plant, filled with Kaldnes rings and supplied with supernatant after dewatering of digested sludge. It was found that a nitrogen removal rate obtained at the pilot plant was 1.9 g m(-2) d(-1). Parallel to the pilot plant run, a series of batch tests were carried out under anoxic and aerobic conditions. Within the batch tests, where the pilot plant's conditions were simulated, removal rates reached up to 3 g N m(-2)d(-1). Moreover, the batch tests with inhibition of Nitrosomonas showed that only the Anammox bacteria (not anoxic removal by Nitrosomonas) are responsible for nitrogen removal.

  15. A robust nitrifying community in a bioreactor at 50 °C opens up the path for thermophilic nitrogen removal.

    PubMed

    Courtens, Emilie Np; Spieck, Eva; Vilchez-Vargas, Ramiro; Bodé, Samuel; Boeckx, Pascal; Schouten, Stefan; Jauregui, Ruy; Pieper, Dietmar H; Vlaeminck, Siegfried E; Boon, Nico

    2016-09-01

    The increasing production of nitrogen-containing fertilizers is crucial to meet the global food demand, yet high losses of reactive nitrogen associated with the food production/consumption chain progressively deteriorate the natural environment. Currently, mesophilic nitrogen-removing microbes eliminate nitrogen from wastewaters. Although thermophilic nitrifiers have been separately enriched from natural environments, no bioreactors are described that couple these processes for the treatment of nitrogen in hot wastewaters. Samples from composting facilities were used as inoculum for the batch-wise enrichment of thermophilic nitrifiers (350 days). Subsequently, the enrichments were transferred to a bioreactor to obtain a stable, high-rate nitrifying process (560 days). The community contained up to 17% ammonia-oxidizing archaea (AOAs) closely related to 'Candidatus Nitrososphaera gargensis', and 25% nitrite-oxidizing bacteria (NOBs) related to Nitrospira calida. Incorporation of (13)C-derived bicarbonate into the respective characteristic membrane lipids during nitrification supported their activity as autotrophs. Specific activities up to 198±10 and 894±81 mg N g(-1) VSS per day for AOAs and NOBs were measured, where NOBs were 33% more sensitive to free ammonia. The NOBs were extremely sensitive to free nitrous acid, whereas the AOAs could only be inhibited by high nitrite concentrations, independent of the free nitrous acid concentration. The observed difference in product/substrate inhibition could facilitate the development of NOB inhibition strategies to achieve more cost-effective processes such as deammonification. This study describes the enrichment of autotrophic thermophilic nitrifiers from a nutrient-rich environment and the successful operation of a thermophilic nitrifying bioreactor for the first time, facilitating opportunities for thermophilic nitrogen removal biotechnology.

  16. A robust nitrifying community in a bioreactor at 50 °C opens up the path for thermophilic nitrogen removal

    PubMed Central

    Courtens, Emilie NP; Spieck, Eva; Vilchez-Vargas, Ramiro; Bodé, Samuel; Boeckx, Pascal; Schouten, Stefan; Jauregui, Ruy; Pieper, Dietmar H; Vlaeminck, Siegfried E; Boon, Nico

    2016-01-01

    The increasing production of nitrogen-containing fertilizers is crucial to meet the global food demand, yet high losses of reactive nitrogen associated with the food production/consumption chain progressively deteriorate the natural environment. Currently, mesophilic nitrogen-removing microbes eliminate nitrogen from wastewaters. Although thermophilic nitrifiers have been separately enriched from natural environments, no bioreactors are described that couple these processes for the treatment of nitrogen in hot wastewaters. Samples from composting facilities were used as inoculum for the batch-wise enrichment of thermophilic nitrifiers (350 days). Subsequently, the enrichments were transferred to a bioreactor to obtain a stable, high-rate nitrifying process (560 days). The community contained up to 17% ammonia-oxidizing archaea (AOAs) closely related to ‘Candidatus Nitrososphaera gargensis', and 25% nitrite-oxidizing bacteria (NOBs) related to Nitrospira calida. Incorporation of 13C-derived bicarbonate into the respective characteristic membrane lipids during nitrification supported their activity as autotrophs. Specific activities up to 198±10 and 894±81 mg N g−1 VSS per day for AOAs and NOBs were measured, where NOBs were 33% more sensitive to free ammonia. The NOBs were extremely sensitive to free nitrous acid, whereas the AOAs could only be inhibited by high nitrite concentrations, independent of the free nitrous acid concentration. The observed difference in product/substrate inhibition could facilitate the development of NOB inhibition strategies to achieve more cost-effective processes such as deammonification. This study describes the enrichment of autotrophic thermophilic nitrifiers from a nutrient-rich environment and the successful operation of a thermophilic nitrifying bioreactor for the first time, facilitating opportunities for thermophilic nitrogen removal biotechnology. PMID:26894446

  17. Particulate Pyrite Autotrophic Denitrification (PPAD) for Remediation of Nitrate-contaminated Groundwater

    NASA Astrophysics Data System (ADS)

    Tong, S.; Rodriguez-Gonzalez, L. C.; Henderson, M.; Feng, C.; Ergas, S. J.

    2015-12-01

    The rapid movement of human civilization towards urbanization, industrialization, and increased agricultural activities has introduced a large amount of nitrate into groundwater. Nitrate is a toxic substance discharged from groundwater to rivers and leads to decreased dissolved oxygen and eutrophication. For this experiment, an electron donor is needed to convert nitrate into non-toxic nitrogen gas. Pyrite is one of the most abundant minerals in the earth's crust making it an ideal candidate as an electron donor. The overall goal of this research was to investigate the potential for pyrite to be utilized as an electron donor for autotrophic denitrification of nitrate-contaminated groundwater. Batch studies of particulate pyrite autotrophic denitrification (PPAD) of synthetic groundwater (100 mg NO3--N L-1) were set up with varying biomass concentration, pyrite dose, and pyrite particle size. Reactors were seeded with mixed liquor volatile suspended solids (VSS) from a biological nitrogen removal wastewater treatment facility. PPAD using small pyrite particles (<0.45mm) resulted in a favorable nitrate removal. The nitrate removal rate increased from 0.26 to 0.34 mg L-1h-1 and then to 0.86 mg L-1h-1, approaching that of the sulfur oxidizing denitrification (SOD) rate of 1.19 mg L-1h-1. Based on Box-Behnken design (BBD) and response surface methodology (RSM), the optimal amount of biomass concentration, pyrite dose, and pyrite particle size were 1,250 mg VSS L-1, 125 g L-1, and 0.815-1.015 mm, respectively. PPAD exhibited substantial nitrate removal rate, lower sulfate accumulation (5.46 mg SO42-/mg NO3--N) and lower alkalinity consumption (1.70 mg CaCO3/mg NO3--N) when compared to SOD (7.54 mg SO42-/mg NO3--N, 4.57 mg CaCO3/mg NO3--N based on stoichiometric calculation). This research revealed that the PPAD process is a promising technique for nitrate-contaminated groundwater treatment and promoted the utilization of pyrite in the field of environmental remediation.

  18. Carbon and nitrogen stable isotope measurements and X-ray photoabsorption spectroscopy of microbial-mat-containing gypsum crust in modern saline pan

    NASA Astrophysics Data System (ADS)

    Isaji, Yuta; Kawahata, Hodaka; Yoshimura, Toshihiro; Kuroda, Junichiro; Ogawa, Nanako O.; Jimenez-Espejo, Francis J.; Lugli, Stefano; Manzi, Vinicio; Roveri, Marco; Tamenori, Yusuke; Ohkouchi, Naohiko

    2015-04-01

    A gypsum crust collected from the Sosalt commercial salt work at Trapani (western Sicily, Italy), which was deposited in several years, has a remarkable layered structure with different colors and physical appearance (from the top to the bottom: transparent gypsum, green layer, and granulous layer containing black particles), each color representing a different microbial community. Previous studies suggest that the colored layers consist of different cyanobacterial communities, purple sulfur bacteria and sulfur reducing bacteria, respectively, and that their biochemical processes are intimately connected (e.g. Caumette et al., 1994; Canfield et al., 2004). In this study we performed stable carbon and nitrogen isotope measurements, elemental mapping, and bulk chemical analyses to describe geochemical characteristics of this layered evaporite deposit. Lower values of δ13C and δ15N in the colored layers compared to the topmost transparent layer indicate active biochemical processes by the bacterial communities, as expected. To further describe the differences between the layers, a synchrotron based micro-X-ray fluorescence (μ-XRF) was used to acquire the spatial distributions of Na, Mg, Sr, S, Cl, and P in the each layer of different color. The elemental mapping combined with chemical speciation of S K-edge X-ray absorption near edge structure (XANES) spectra of the gypsum crust showed that the transparent and the green layers were uniformly filled with gypsum crystals, while a somewhat high concentration of elements other than sulfur were observed in the interparticle realm of the bottom gypsum layer. This indicates an earliest alteration at the bottom layer probably as a result of sulfur reduction by sulfur reducing bacteria inhabiting the interparticle realm. It is noteworthy that no reduced sulfur compounds, except for gypsum, was detected in the sample by μ-XANES analysis, despite the presence of a layer inhabited by sulfur reducing bacteria. Since gypsum is

  19. Estimating tissue-specific discrimination factors and turnover rates of stable isotopes of nitrogen and carbon in the smallnose fanskate Sympterygia bonapartii (Rajidae).

    PubMed

    Galván, D E; Jañez, J; Irigoyen, A J

    2016-08-01

    This study aimed to estimate trophic discrimination factors (TDFs) and metabolic turnover rates of nitrogen and carbon stable isotopes in blood and muscle of the smallnose fanskate Sympterygia bonapartii by feeding six adult individuals, maintained in captivity, with a constant diet for 365 days. TDFs were estimated as the difference between δ(13) C or δ(15) N values of the food and the tissues of S. bonapartii after they had reached equilibrium with their diet. The duration of the experiment was enough to reach the equilibrium condition in blood for both elements (estimated time to reach 95% of turnover: C t95%blood  = 150 days, N t95%blood  = 290 days), whilst turnover rates could not be estimated for muscle because of variation among samples. Estimates of Δ(13) C and Δ(15) N values in blood and muscle using all individuals were Δ(13) Cblood = 1·7‰, Δ(13) Cmuscle = 1·3‰, Δ(15) Nblood = 2·5‰ and Δ(15) Nmuscle = 1·5‰, but there was evidence of differences of c.0·4‰ in the Δ(13) C values between sexes. The present values for TDFs and turnover rates constitute the first evidence for dietary switching in batoids based on long-term controlled feeding experiments. Overall, the results showed that S. bonapartii has relatively low turnover rates and isotopic measurements would not track seasonal movements adequately. The estimated Δ(13) C values in S. bonapartii blood and muscle were similar to previous estimations for elasmobranchs and to generally accepted values in bony fishes (Δ(13) C = 1·5‰). For Δ(15) N, the results were similar to published reports for blood but smaller than reports for muscle and notably smaller than the typical values used to estimate trophic position (Δ(15) N c. 3·4‰). Thus, trophic position estimations for elasmobranchs based on typical Δ(15) N values could lead to underestimates of actual trophic positions. Finally, the evidence of differences in TDFs between sexes reveals a need for more

  20. Serum carbon and nitrogen stable isotopes as potential biomarkers of dietary intake and their relation with incident type 2 diabetes: the EPIC-Norfolk study123

    PubMed Central

    Patel, Pinal S; Cooper, Andrew JM; O'Connell, Tamsin C; Kuhnle, Gunter GC; Kneale, Catherine K; Mulligan, Angela M; Luben, Robert N; Brage, Soren; Khaw, Kay-Tee; Wareham, Nicholas J; Forouhi, Nita G

    2014-01-01

    Background: Stable-isotope ratios of carbon (13C/12C, expressed as δ13C) and nitrogen (15N/14N, or δ15N) have been proposed as potential nutritional biomarkers to distinguish between meat, fish, and plant-based foods. Objective: The objective was to investigate dietary correlates of δ13C and δ15N and examine the association of these biomarkers with incident type 2 diabetes in a prospective study. Design: Serum δ13C and δ15N (‰) were measured by using isotope ratio mass spectrometry in a case-cohort study (n = 476 diabetes cases; n = 718 subcohort) nested within the European Prospective Investigation into Cancer and Nutrition (EPIC)–Norfolk population-based cohort. We examined dietary (food-frequency questionnaire) correlates of δ13C and δ15N in the subcohort. HRs and 95% CIs were estimated by using Prentice-weighted Cox regression. Results: Mean (±SD) δ13C and δ15N were −22.8 ± 0.4‰ and 10.2 ± 0.4‰, respectively, and δ13C (r = 0.22) and δ15N (r = 0.20) were positively correlated (P < 0.001) with fish protein intake. Animal protein was not correlated with δ13C but was significantly correlated with δ15N (dairy protein: r = 0.11; meat protein: r = 0.09; terrestrial animal protein: r = 0.12, P ≤ 0.013). δ13C was inversely associated with diabetes in adjusted analyses (HR per tertile: 0.74; 95% CI: 0.65, 0.83; P-trend < 0.001], whereas δ15N was positively associated (HR: 1.23; 95% CI: 1.09, 1.38; P-trend = 0.001). Conclusions: The isotope ratios δ13C and δ15N may both serve as potential biomarkers of fish protein intake, whereas only δ15N may reflect broader animal-source protein intake in a European population. The inverse association of δ13C but a positive association of δ15N with incident diabetes should be interpreted in the light of knowledge of dietary intake and may assist in identifying dietary components that are associated with health risks and benefits. PMID:24990425

  1. Food-web structure and trophodynamics of mesopelagic-suprabenthic bathyal macrofauna of the Algerian Basin based on stable isotopes of carbon and nitrogen

    NASA Astrophysics Data System (ADS)

    Fanelli, E.; Cartes, J. E.; Rumolo, P.; Sprovieri, M.

    2009-09-01

    The trophodynamics of mesopelagic (macrozooplankton/micronekton) and benthic boundary layer (suprabenthos=hyperbenthos) faunas from the Algerian Basin were characterized on a seasonal scale through stable carbon and nitrogen isotopic analyses of a total of 34 species and two broad taxa (Copepoda and Cumacea). This is the first study simultaneously focused on trophodynamics of deep-sea zooplankton and suprabenthos. Samples were collected southeast of Mallorca (Algerian Basin, Western Mediterranean), on the continental slope close to Cabrera Archipelago, at 650-780 m depths, ca. bi-monthly between August 2003 and June 2004. Mean δ 13C values of suprabenthos ranged from -21.1‰ ( Munnopsurus atlanticus) to -16.7‰ ( Cyclaspis longicaudata). Values of δ 15N ranged from 2.8‰ ( Lepechinella manco) to 9.9‰ (larvae of Gnathia sp.). The stable isotope ratios of suprabenthic fauna displayed a continuum of values, confirming a wide spectrum of feeding guilds (from filter feeders/surface deposit feeders to predators). According to the available information on diets for suprabenthic species, the highest annual mean δ 15N values were found for the hematophagous isopod Gnathia sp. parasite on fish (represented by Praniza larvae) and carnivorous amphipods (e.g. Rhachotropis spp., Nicippe tumida) consuming copepods, and the lowest δ 15N values were found for two cumaceans ( Cyclaspis longicaudata and Platysympus typicus) feeding on detritus. Assuming a 15N-enrichment factor of 2.5‰ and deposit feeders as baseline, we found three trophic levels in suprabenthic food webs. δ 13C ranges were particularly wide among deposit feeders (ranging from -21.8% to -17.3‰) and omnivores (from -20.5% to -18.8‰), suggesting exploitation of particulate organic matter (POM) of different characteristics. Our isotopic analyses revealed lower ranges of δ 13C and δ 15N for macrozooplankton/micronekton, compared with suprabenthos. δ 13C values of zooplankton taxa ranged from -21.1

  2. Metabolic potential of microbial mats and microbialites: Autotrophic capabilities described by an in silico stoichiometric approach from shared genomic resources.

    PubMed

    Cerqueda-García, Daniel; Falcón, Luisa I

    2016-08-01

    Microbialites and microbial mats are complex communities with high phylogenetic diversity. These communities are mostly composed of bacteria and archaea, which are the earliest living forms on Earth and relevant to biogeochemical evolution. In this study, we identified the shared metabolic pathways for uptake of inorganic C and N in microbial mats and microbialites based on metagenomic data sets. An in silico analysis for autotrophic pathways was used to trace the paths of C and N to the system, following an elementary flux modes (EFM) approach, resulting in a stoichiometric model. The fragility was analyzed by the minimal cut sets method. We found four relevant pathways for the incorporation of CO2 (Calvin cycle, reverse tricarboxylic acid cycle, reductive acetyl-CoA pathway, and dicarboxylate/4-hydroxybutyrate cycle), some of them present only in archaea, while nitrogen fixation was the most important source of N to the system. The metabolic potential to incorporate nitrate to biomass was also relevant. The fragility of the network was low, suggesting a high redundancy of the autotrophic pathways due to their broad metabolic diversity, and highlighting the relevance of reducing power source. This analysis suggests that microbial mats and microbialites are "metabolic pumps" for the incorporation of inorganic gases and formation of organic matter.

  3. Implication of Industrial Waste for Biomass and Lipid Production in Chlorella minutissima Under Autotrophic, Heterotrophic, and Mixotrophic Grown Conditions.

    PubMed

    Dubey, Kashyap Kumar; Kumar, Sudhir; Dixit, Deepak; Kumar, Punit; Kumar, Dhirendra; Jawed, Arshad; Haque, Shafiul

    2015-07-01

    Following the diminishing hopes from the first and second generation biofuels, mainly due to the limitations of land availability, feed stock requirements, and complicated pre-treatments, third generation biofuels from microalgae are becoming a priority in the current scenario. The present study focuses on comparison and optimization of lipid accumulation efficiency in algal strain Chlorella minutissima grown under autotrophic, heterotrophic, and mixotrophic modes of nutrition, employing various carbon sources obtained from cheap industrial wastes such as glucose, acetate, and glycerol. Other pertinent factors such as the effect of various nitrogen sources, effect of salinity on the cell growth, and lipid accumulations in the algal cells were also studied. The results suggested that C. minutissima can grow efficiently under autotrophic, heterotrophic, and mixotrophic modes of nutrition. C. minutissima cells were capable of utilizing other non-popular carbon sources such as glycerol and acetate collected as waste products from different industries along with commonly used glucose. The maximum biomass concentration (8.9 g/L) and lipid content (36.19 %) were found in heterotrophic mode of nutrition. Our findings indicated that C. minutissima can efficiently utilize these cheaper carbon sources from industrial waste products for its growth and the production cost of various bioenergy sources can be reduced significantly.

  4. Perchlorate reduction by hydrogen autotrophic bacteria in a bioelectrochemical reactor.

    PubMed

    Wang, Zichao; Gao, Mengchun; Zhang, You; She, Zonglian; Ren, Yun; Wang, Zhe; Zhao, Congcong

    2014-09-01

    The autotrophic hydrogen reduction of perchlorate was investigated in batch modes in a proton-exchange membrane bioelectrochemical reactor. The phylogenic characterization of hydrogen-autotrophic perchlorate-reducing cultures in the cathode cell mainly included the genera Aureibacter tunicatorum, Fulvivirga kasyanovii, Thermotalea metallivorans (T), bacterium WHC2-6, and Thauera sp. Q20-C. The suitable H2SO4 supplement concentration was identified to be between 0.04 and 0.05 mol L(-1) in the anode cell. The perchlorate reduction was affected by the sludge concentration in the cathode cell, current intensity, and initial perchlorate concentration. The removal efficiency of perchlorate positively correlated with the current intensity, and the current intensity of 20, 40, 50, and 60 mA corresponded to removal efficiencies of 95.03, 96.29, 97.56 and 98.99%, respectively. When the current intensity was sufficient for hydrogen production, the kinetics of the perchlorate reduction conformed to a zero-order kinetics model, and the maximum specific substrate utilization rates for perchlorate (Vmax) ranged from 5.52 to 14.34 mg ClO4(-) g(-1) volatile suspended solid (VSS) h(-1). Copyright © 2014 Elsevier Ltd. All rights reserved.

  5. Trophic dynamics of scleractinian corals: stable isotope evidence.

    PubMed

    Tremblay, Pascale; Maguer, Jean François; Grover, Renaud; Ferrier-Pagès, Christine

    2015-04-15

    Reef-building corals form symbioses with dinoflagellates from the diverse genus Symbiodinium. This symbiotic association has developed adaptations to acquire and share nutrients, which are essential for its survival and growth in nutrient-poor tropical waters. The host is thus able to prey on a wide range of organic food sources (heterotrophic nutrition) whereas the symbionts acquire most of the inorganic nutrients (autotrophic nutrition). However, nutrient fluxes between the two partners remain unclear, especially concerning heterotrophically acquired carbon and nitrogen. We combined physiological measurements and pulse-chase isotopic labeling of heterotrophic carbon and nitrogen, as well as autotrophic carbon to track nutrient fluxes in two coral species, Stylophora pistillata and Turbinaria reniformis, in symbiosis with Symbiodinium clades A, and C,D respectively. We showed a rapid acquisition, exchange and a long-term retention of heterotrophic nutrients within the symbiosis, whereas autotrophic nutrients were rapidly used to meet immediate metabolic needs. In addition, there was a higher retention of heterotrophic nitrogen compared with carbon, in agreement with the idea that tropical corals are nitrogen-limited. Finally, a coupling between auto- and heterotrophy was observed in the species S. pistillata, with a higher acquisition and retention of heterotrophic nutrients under low irradiance to compensate for a 50% reduction in autotrophic nutrient acquisition and translocation. Conversely, T. reniformis conserved an equivalent heterotrophic nutrient acquisition at both light levels because this coral species did not significantly reduce its rates of gross photosynthesis and autotrophic carbon acquisition between the two irradiances. These experiments advance the current understanding of the nutrient exchanges between the two partners of a symbiotic association, providing evidence of the complexity of the host-symbiont relationship. © 2015. Published by The

  6. Pyrite-based autotrophic denitrification for remediation of nitrate contaminated groundwater.

    PubMed

    Pu, Jiaoyang; Feng, Chuanping; Liu, Ying; Li, Rui; Kong, Zhe; Chen, Nan; Tong, Shuang; Hao, Chunbo; Liu, Ye

    2014-12-01

    In this study, pyrite-based denitrification using untreated pyrite (UP) and acid-pretreated pyrite (AP) was evaluated as an alternative to elemental sulfur based denitrification. Pyrite-based denitrification resulted in a favorable nitrate removal rate constant (0.95 d(-1)), sulfate production of 388.00 mg/L, and a stable pH. The pretreatment of pyrite with acid led to a further increase in the nitrate removal rate constant (1.03 d(-1)) and reduction in initial sulfate concentration (224.25±7.50 mg/L). By analyzing the microbial community structure using Denaturing Gradient Gel Electrophoresis, it was confirmed that Sulfurimonas denitrificans (S. denitrificans) could utilize pyrite as an electron donor. A stable pH was observed over the entire experimental period, indicating that the use of a pH buffer reagent would not be necessary for pyrite-based denitrification. Therefore, pyrite could effectively replace elemental sulfur as an electron donor in autotrophic denitrification for nitrate-contaminated groundwater remediation.

  7. Nitrogen removal from digested black water by one-stage partial nitritation and anammox.

    PubMed

    Vlaeminck, Siegfried E; Terada, Akihiko; Smets, Barth F; van der Linden, Davy; Boon, Nico; Verstraete, Willy; Carballa, Marta

    2009-07-01

    This study assessed the technical feasibility to treat digested black water from vacuum toilets (> 1000 mg NH4(+)-N L(-1)) in a lab-scale oxygen-limited autotrophic nitrification/denitrification (OLAND) rotating biological contactor. After an adaptation period of 2.5 months, a stable nitrogen removal rate of ca. 700 mg N L(-1) d(-1) was reached over the subsequent 5 months. Suppression of the nitrite oxidizing bacteria at free ammonia levels above 3 mg N L(-1) resulted in a nitrogen removal efficiency of 76%. The favorable ratios of both organic and inorganic carbon to nitrogen guaranteed endured anammox activity and sufficient buffering capacity, respectively. Quantitative FISH showed that aerobic and anoxic ammonium-oxidizing bacteria (AerAOB and AnAOB) made up 43 and 8% of the biofilm, respectively. Since a part of the AerAOB was probably present in anoxic biofilm zones; their specific ammonium conversion was very low, in contrast to the high specific AnAOB activity. DGGE analysis showed that the dominant AerAOB and AnAOB species were resistant to the transition from synthetic medium to digested black water. This study demonstrates high-rate nitrogen removal from digested black water by one-stage partial nitritation and anammox, which will allow a significant decrease in operational costs compared to conventional nitrification/ denitrification.

  8. How Stable Is Stable?

    ERIC Educational Resources Information Center

    Baehr, Marie

    1994-01-01

    Provides a problem where students are asked to find the point at which a soda can floating in some liquid changes its equilibrium between stable and unstable as the soda is removed from the can. Requires use of Newton's first law, center of mass, Archimedes' principle, stable and unstable equilibrium, and buoyant force position. (MVL)

  9. How Stable Is Stable?

    ERIC Educational Resources Information Center

    Baehr, Marie

    1994-01-01

    Provides a problem where students are asked to find the point at which a soda can floating in some liquid changes its equilibrium between stable and unstable as the soda is removed from the can. Requires use of Newton's first law, center of mass, Archimedes' principle, stable and unstable equilibrium, and buoyant force position. (MVL)

  10. Metabolic engineering of Cupriavidus necator for heterotrophic and autotrophic alka(e)ne production.

    PubMed

    Crépin, Lucie; Lombard, Eric; Guillouet, Stéphane E

    2016-09-01

    Alkanes of defined carbon chain lengths can serve as alternatives to petroleum-based fuels. Recently, microbial pathways of alkane biosynthesis have been identified and enabled the production of alkanes in non-native producing microorganisms using metabolic engineering strategies. The chemoautotrophic bacterium Cupriavidus necator has great potential for producing chemicals from CO2: it is known to have one of the highest growth rate among natural autotrophic bacteria and under nutrient imbalance it directs most of its carbon flux to the synthesis of the acetyl-CoA derived polymer, polyhydroxybutyrate (PHB), (up to 80% of intracellular content). Alkane synthesis pathway from Synechococcus elongatus (2 genes coding an acyl-ACP reductase and an aldehyde deformylating oxygenase) was heterologously expressed in a C. necator mutant strain deficient in the PHB synthesis pathway. Under heterotrophic condition on fructose we showed that under nitrogen limitation, in presence of an organic phase (decane), the strain produced up to 670mg/L total hydrocarbons containing 435mg/l of alkanes consisting of 286mg/l of pentadecane, 131mg/l of heptadecene, 18mg/l of heptadecane, and 236mg/l of hexadecanal. We report here the highest level of alka(e)nes production by an engineered C. necator to date. We also demonstrated the first reported alka(e)nes production by a non-native alkane producer from CO2 as the sole carbon source. Copyright © 2016 International Metabolic Engineering Society. Published by Elsevier Inc. All rights reserved.

  11. Characterization of an autotrophic sulfide-oxidizing marine Arcobacter sp. that produces filamentous sulfur.

    PubMed

    Wirsen, C O; Sievert, S M; Cavanaugh, C M; Molyneaux, S J; Ahmad, A; Taylor, L T; DeLong, E F; Taylor, C D

    2002-01-01

    A coastal marine sulfide-oxidizing autotrophic bacterium produces hydrophilic filamentous sulfur as a novel metabolic end product. Phylogenetic analysis placed the organism in the genus Arcobacter in the epsilon subdivision of the Proteobacteria. This motile vibrioid organism can be considered difficult to grow, preferring to grow under microaerophilic conditions in flowing systems in which a sulfide-oxygen gradient has been established. Purified cell cultures were maintained by using this approach. Essentially all 4',6-diamidino-2-phenylindole dihydrochloride-stained cells in a flowing reactor system hybridized with Arcobacter-specific probes as well as with a probe specific for the sequence obtained from reactor-grown cells. The proposed provisional name for the coastal isolate is "Candidatus Arcobacter sulfidicus." For cells cultured in a flowing reactor system, the sulfide optimum was higher than and the CO(2) fixation activity was as high as or higher than those reported for other sulfur oxidizers, such as Thiomicrospira spp. Cells associated with filamentous sulfur material demonstrated nitrogen fixation capability. No ribulose 1,5-bisphosphate carboxylase/oxygenase could be detected on the basis of radioisotopic activity or by Western blotting techniques, suggesting an alternative pathway of CO(2) fixation. The process of microbial filamentous sulfur formation has been documented in a number of marine environments where both sulfide and oxygen are available. Filamentous sulfur formation by "Candidatus Arcobacter sulfidicus" or similar strains may be an ecologically important process, contributing significantly to primary production in such environments.

  12. Investigation of solid-phase buffers for sulfur-oxidizing autotrophic denitrification.

    PubMed

    Sengupta, Sukalyan; Ergas, Sarina J; Lopez-Luna, Erika

    2007-12-01

    This paper investigates biological denitrification using autotrophic microorganisms that use elemental sulfur as an electron donor. In this process, for each gram of nitrate-nitrogen removed, approximately 4.5 g of alkalinity (as calcium carbonate) are consumed. Because denitrification is severely inhibited below pH 5.5, and alkalinity present in the influent wastewaters is less than the alkalinity consumed, an external buffer was needed to arrest any drop in pH from alkalinity consumption. A packed-bed bioreactor configuration is ideally suited to handle variations in flow and nitrate loading from decentralized wastewater treatment systems, as it is a passive system and thus requires minimal maintenance; therefore, a solid-phase buffer packed with the elemental sulfur in the bioreactor is most suitable. In this research, marble chips, limestone, and crushed oyster shells were tested as solid-phase buffers. Bench- and field-scale studies indicated that crushed oyster shell was the most suitable buffer based on (1) the rate of dissolution of buffer and the buffering agent released (carbonate, bicarbonate, or hydroxide), (2) the ability of the buffer surface to act as host for microbial attachment, (3) turbidity of the solution upon release of the buffering agent, and (4) economics.

  13. Evaluation of Nitrous Oxide Emission from Sulfide- and Sulfur-Based Autotrophic Denitrification Processes.

    PubMed

    Liu, Yiwen; Peng, Lai; Ngo, Huu Hao; Guo, Wenshan; Wang, Dongbo; Pan, Yuting; Sun, Jing; Ni, Bing-Jie

    2016-09-06

    Recent studies have shown that sulfide- and sulfur-based autotrophic denitrification (AD) processes play an important role in contributing to nitrous oxide (N2O) production and emissions. However, N2O production is not recognized in the current AD models, limiting their ability to predict N2O accumulation during AD. In this work, a mathematical model is developed to describe N2O dynamics during sulfide- and sulfur-based AD processes for the first time. The model is successfully calibrated and validated using N2O data from two independent experimental systems with sulfide or sulfur as electron donors for AD. The model satisfactorily describes nitrogen reductions, sulfide/sulfur oxidation, and N2O accumulation in both systems. Modeling results revealed substantial N2O accumulation due to the relatively low N2O reduction rate during both sulfide- and sulfur-based AD processes. Application of the model to simulate long-term operations of activated sludge systems performing sulfide- and sulfur-based AD processes indicates longer sludge retention time reduced N2O emission. For sulfide-based AD process, higher initial S/N ratio also decreased N2O emission but with a higher operational cost. This model can be a useful tool to support process operation optimization for N2O mitigation during AD with sulfide or sulfur as electron donor.

  14. Using stable isotopes to reconcile differences in nitrogen uptake efficiency relative to late season fertilization of northern red oak seedlings in Wisconsin bare-root nurseries

    NASA Astrophysics Data System (ADS)

    Fujinuma, R.; Balster, N. J.

    2009-12-01

    Cultural applications (e.g., timing, amount) of nitrogen (N) fertilizer in bareroot tree nurseries have been assessed for some time. However, the use of different metrologies to quantify the efficient use of fertilizer N and its allocation within biomass has confounded comparisons between fertilization regimes. This inconsistency is especially problematic when quantifying N fertilizer uptake efficiency (NFUE) of late season N fertilization in northern red oak (Quercus rubra L.) (NRO) seedlings characterized by episodic flushes in growth and N storage in perennial tissue to support spring growth. The use of isotopic tracers could help elucidate these differences. We therefore hypothesized that: 1) calculations of NFUE using isotopically enriched fertilizer would yield lower, more precise estimates of NFUE relative to traditional methods due to differences in the accounting of mineralized and reabsorbed N, and 2) a significant fraction of leaf N in older leaves (early flushes) would be reabsorbed into root and shoot tissue before abscission relative to leaves produced toward the end of the growing season (late flushes). To test these hypotheses, we conducted an experiment in two-year old NRO seedlings at two bare-root nurseries in Wisconsin. We applied a total of 147 mg N seedling-1 in pulses from early July after the seedlings completed their second leaf flush until late August. The treatments consisted of three replicated plots of 15N enriched (1.000 atom%) ammonium sulfate, three non-enriched plots, and three unfertilized plots (controls) at each nursery. Subsequent changes in plant N uptake and N allocation were quantified from destructively harvested samples taken at 40, 60, and 120 days after the fertilization began. We evaluated three common methods currently used to estimate NFUE (total N without control, total N with control, and isotopic difference). The total N without control method overestimated mean NFUE by 3.2 times relative to the isotope method

  15. Autotrophic growth and lipid production of Chlorella sorokiniana in lab batch and BIOCOIL photobioreactors: Experiments and modeling.

    PubMed

    Concas, Alessandro; Malavasi, Veronica; Costelli, Cristina; Fadda, Paolo; Pisu, Massimo; Cao, Giacomo

    2016-07-01

    A novel mathematical model for the quantitative assessment of the effect of dissolved nitrogen on the autotrophic batch-growth and lipid accumulation of Chlorella sorokiniana, is proposed in this work. Model results have been validated through comparison with suitable experimental data performed in lab photobioreactors. Further experiments have been then performed using the BIOCOIL photobioreactor operated in fed-batch mode. The experimental results, which show that a maximum growth rate of 0.52day(-1) and a lipid content equal to 25%wt can be achieved with the BIOICOIL, have been successfully predicted through the proposed model. Therefore, the model might represent a first step toward the development of a tool for the scale-up and optimization of the operating conditions of BIOCOIL photobioreactors. Finally, the fatty acid methyl esters obtained by trans-esterification of lipids extracted from C. sorokiniana, have been analyzed in view of the assessment of their usability for producing biodiesel.

  16. Evolutionarily stable strategy carbon allocation to foliage, wood, and fine roots in trees competing for light and nitrogen: an analytically tractable, individual-based model and quantitative comparisons to data.

    PubMed

    Dybzinski, Ray; Farrior, Caroline; Wolf, Adam; Reich, Peter B; Pacala, Stephen W

    2011-02-01

    We present a model that scales from the physiological and structural traits of individual trees competing for light and nitrogen across a gradient of soil nitrogen to their community-level consequences. The model predicts the most competitive (i.e., the evolutionarily stable strategy [ESS]) allocations to foliage, wood, and fine roots for canopy and understory stages of trees growing in old-growth forests. The ESS allocations, revealed as analytical functions of commonly measured physiological parameters, depend not on simple root-shoot relations but rather on diminishing returns of carbon investment that ensure any alternate strategy will underperform an ESS in monoculture because of the competitive environment that the ESS creates. As such, ESS allocations do not maximize nitrogen-limited growth rates in monoculture, highlighting the underappreciated idea that the most competitive strategy is not necessarily the "best," but rather that which creates conditions in which all others are "worse." Data from 152 stands support the model's surprising prediction that the dominant structural trade-off is between fine roots and wood, not foliage, suggesting the "root-shoot" trade-off is more precisely a "root-stem" trade-off for long-lived trees. Assuming other resources are abundant, the model predicts that forests are limited by both nitrogen and light, or nearly so.

  17. Integration of sulphate reduction, autotrophic denitrification and nitrification to achieve low-cost excess sludge minimisation for Hong Kong sewage.

    PubMed

    Lau, G N; Sharma, K R; Chen, G H; van Loosdrecht, M C M

    2006-01-01

    An integrated anaerobic-aerobic treatment system of sulphate-laden wastewater was proposed here to achieve low sludge production, low energy consumption and effective sulphide control. Before integrating the whole system, the feasibility of autotrophic denitrification utilising dissolved sulphide produced during anaerobic treatment of sulphate rich wastewater was studied here. An upflow anaerobic sludge blanket reactor was operated to treat sulphate-rich synthetic wastewater (TOC=100 mg/L and sulphate=500 mg/L) and its effluent with dissolved sulphide and external nitrate solution were fed into an anoxic biofilter. The anaerobic reactor was able to remove 77-85% of TOC at HRT of 3 h and produce 70-90 mg S/L sulphide in dissolved form for the subsequent denitrification. The performance of anoxic reactor was stable, and the anoxic reactor could remove 30 mg N/L nitrate at HRT of 2 h through autotrophic denitrification. Furthermore, sulphur balance for the anoxic filter showed that more than 90% of the removed sulphide was actually oxidised into sulphate, thereby there was no accumulation of sulphur particles in the filter bed. The net sludge productions were approximately 0.15 to 0.18 g VSS/g COD in the anaerobic reactor and 0.22 to 0.31 g VSS/g NO3- -N in the anoxic reactor. The findings in this study will be helpful in developing the integrated treatment system to achieve low-cost excess sludge minimisation.

  18. Autotrophic denitrification performance and bacterial community at biocathodes of bioelectrochemical systems with either abiotic or biotic anodes.

    PubMed

    Nguyen, Van Khanh; Hong, Sungsug; Park, Younghyun; Jo, Kyungmin; Lee, Taeho

    2015-02-01

    Two-chamber bioelectrochemical systems (BESs) have recently been developed for nitrate removal from nitrate-contaminated water. In this study, we compared the nitrate removal performance of biocathodes of BESs when using abiotic and biotic anodes. Acetate was used as electron donor in BESs with biotic anode, whereas a direct current power supply was used as energy source in BESs with abiotic anode. The nitrogen removal efficiency increased from 18.1% to 43.0% when the voltage supplied to the BES with abiotic anode increased from 0.7 V to 0.9 V, whereas no higher removal efficiency was obtained at a higher supplied voltage (1.1 V). The highest efficiency (78.0%) of autotrophic nitrogen removal was achieved when electron transfer from the biotic anode chamber of BESs was used. Unexpectedly, control of the cathode potential did not enhance nitrate removal in BESs with biotic anode. Special attention was paid to elucidate the differences of bacterial communities catalysing autotrophic denitrification in the biocathodes of BESs with abiotic and biotic anodes. Data from denaturing gradient gel electrophoresis and phylogenetic analysis suggested that denitrification in BESs with abiotic anode could be attributed to Nitratireductor sp., Shinella sp., and Dyella sp., whereas the dominant bacterial denitrifiers in BESs with biotic anode were found to be Pseudomonas sp., Curtobacterium sp., and Aeromonas sp. These results implied that biocathodes of BESs with biotic anode are more efficient than those of BESs with abiotic anode for nitrate removal from nitrate-contaminated water in practical applications. Copyright © 2014 The Society for Biotechnology, Japan. Published by Elsevier B.V. All rights reserved.

  19. Complex interactions between autotrophs in shallow marine and freshwater ecosystems: implications for community responses to nutrient stress.

    PubMed

    Havens, K E; Hauxwell, J; Tyler, A C; Thomas, S; McGlathery, K J; Cebrian, J; Valiela, I; Steinman, A D; Hwang, S J

    2001-01-01

    The relative biomass of autotrophs (vascular plants, macroalgae, microphytobenthos, phytoplankton) in shallow aquatic ecosystems is thought to be controlled by nutrient inputs and underwater irradiance. Widely accepted conceptual models indicate that this is the case both in marine and freshwater systems. In this paper we examine four case studies and test whether these models generally apply. We also identify other complex interactions among the autotrophs that may influence ecosystem response to cultural eutrophication. The marine case studies focus on macroalgae and its interactions with sediments and vascular plants. The freshwater case studies focus on interactions between phytoplankton, epiphyton, and benthic microalgae. In Waquoit Bay, MA (estuary), controlled experiments documented that blooms of macroalgae were responsible for the loss of eelgrass beds at nutrient-enriched locations. Macroalgae covered eelgrass and reduced irradiance to the extent that the plants could not maintain net growth. In Hog Island Bay, VA (estuary), a dense lawn of macroalgae covered the bottom sediments. There was reduced sediment-water nitrogen exchange when the algae were actively growing and high nitrogen release during algal senescence. In Lakes Brobo (West Africa) and Okeechobee (FL), there were dramatic seasonal changes in the biomass and phosphorus content of planktonic versus attached algae, and these changes were coupled with changes in water level and abiotic turbidity. Deeper water and/or greater turbidity favored dominance by phytoplankton. In Lake Brobo there also was evidence that phytoplankton growth was stimulated following a die-off of vascular plants. The case studies from Waquoit Bay and Lake Okeechobee support conceptual models of succession from vascular plants to benthic algae to phytoplankton along gradients of increasing nutrients and decreasing under-water irradiance. The case studies from Hog Island Bay and Lake Brobo illustrate additional effects

  20. Dual stable isotopic analysis of nitrogen and oxygen to evaluate sources and sinks of atmospheric anthropogenic nitrate in the Colorado Desert

    NASA Astrophysics Data System (ADS)

    Bell, M. D.; Allen, E. B.; Sickman, J. O.

    2010-12-01

    Industrial, automotive, and agricultural emissions release nitrogen into the atmosphere which is subsequently deposited to the surrounding terrestrial ecosystem. The Colorado Desert is impacted by nitrogen deposition from the west due to inputs from the Los Angeles air basin as well as nearby sources from agriculture in the Coachella Valley (CV). Current research within the Colorado Desert has demonstrated that anthropogenic N deposition contributes to the increased biomass of exotic invasive grasses, which compete with native species and can create enough biomass to carry fire in areas of high deposition. To measure the anthropogenic nitrogen within the CV, an array of passive air samplers was erected spanning the valley from west to east. Each sampler contained filters to passively collect both nitric acid and ammonia ions. To evaluate the degree to which the local ecosystem is supplemented by atmospheric N and determine how nitrogen pools are transformed, surface soil and leaf tissue of the dominant shrub, Larrea tridentata, were collected at each site. Only nitrate data from the samplers has currently been analyzed. δ15N, δ17O, and δ18O were obtained from atmospheric and 1M KCl soil extracts using dual isotopic analysis of NO3-. δ15N of vegetation was obtained through combustion of dried leaf tissue. The highest concentrations of atmospheric nitrate are located on the western edge of the desert in the direction toward Los Angeles, and there is also high nitrate near the Salton Sea. The isoscape produced by the isotopic analysis provides a map further describing how NO3- molecules are moving through the desert. This map shows which sources are influencing deposition sinks across the valley. Soil concentrations of nitrogen increase along the same gradient and have an inverse relationship with δ15N. Plant tissue is also less enriched in δ15N at high deposition sites, which correlates with soil values and may be caused by increased fractionation of nitrogen