Nitrogen cycling in a forest stream determined by a 15N tracer addition

Science.gov (United States)

Patrick J. Mullholland; Jennifer L. Tank; Diane M. Sanzone; Wilfred M. Wollheim; Bruce J. Peterson; Jackson R. Webster; Judy L. Meyer

2000-01-01

Nitrogen uptake and cycling was examined using a six-week tracer addition of 15N-labeled ammonium in early spring in Waer Branch, a first-order deciduous forest stream in eastern Tennessee. Prior to the 15N addition, standing stocks of N were determined for the major biomass compartments. During and after the addition,

Effects of experimental nitrogen additions on plant diversity in tropical forests of contrasting disturbance regimes in southern China

International Nuclear Information System (INIS)

Lu Xiankai; Mo Jiangming; Gilliam, Frank S.; Yu Guirui; Zhang Wei; Fang Yunting; Huang Juan

2011-01-01

Responses of understory plant diversity to nitrogen (N) additions were investigated in reforested forests of contrasting disturbance regimes in southern China from 2003 to 2008: disturbed forest (with harvesting of understory vegetation and litter) and rehabilitated forest (without harvesting). Experimental additions of N were administered as the following treatments: Control, 50 kg N ha -1 yr -1 , and 100 kg N ha -1 yr -1 . Nitrogen additions did not significantly affect understory plant richness, density, and cover in the disturbed forest. Similarly, no significant response was found for canopy closure in this forest. In the rehabilitated forest, species richness and density showed no significant response to N additions; however, understory cover decreased significantly in the N-treated plots, largely a function of a significant increase in canopy closure. Our results suggest that responses of plant diversity to N deposition may vary with different land-use history, and rehabilitated forests may be more sensitive to N deposition. - Highlights: → Nitrogen addition had no significant effect on understory plant diversity in the disturbed forest. → Nitrogen addition significantly decreased understory plant cover. → Nitrogen addition had no effect on richness and density in the rehabilitated forest. → The decrease is largely a function of a significant increase in canopy closure. → Land-use practices may dominate the responses of plant diversity to N addition. - Research in disturbed forests of southeastern China demonstrates that land-use history can substantially alter effects of excess nitrogen deposition on plant diversity of tropical forest ecosystems.

Alteration of belowground carbon dynamics by nitrogen addition in southern California mixed conifer forests

Science.gov (United States)

N.S. Nowinski; S.E. Trumbore; G. Jimenez; M.E. Fenn

2009-01-01

Nitrogen deposition rates in southern California are the highest in North America and have had substantial effects on ecosystem functioning. We document changes in the belowground C cycle near ponderosa pine trees experiencing experimental nitrogen (N) addition (50 and 150 kg N ha−1 a−1 as slow release urea since 1997) at two end‐member...

The Effects of Application Vinasseand additive nitrogen and phosphorus on Growth and Yield of Tomato

Directory of Open Access Journals (Sweden)

Ahmad Golchin

2017-02-01

Full Text Available Introduction:Vinasse is a byproduct of the sugar industry. Sugarcane or Sugarbeet is processed to produce crystallinesugar, pulp and molasses. The latter isfurther processed by fermentation to ethanol, ascorbicacid or other products. After the removal of the desired product (alcohol, ascorbicacid, etc. the remaining material is called vinasse. Vinasse is sold after a partial dehydration and usually has a viscositycomparable to molasses. Commercially offered vinasse comes either from sugarcaneand is called cane-vinasse or from sugarbeet and is called beet-vinasse. On average, for each liter of vinasse, 12 liters alcohol produced. Vinasse is a material with dark brown color and the smell of burned sugar, which is rich in potassium, calcium, magnesium, phosphorus and nitrogen. Materials and Methods:To determine the effect of vinasse and additive nitrogen and phosphorus on growth and yield of tomato, a factorial pot experiment was conducted at ZanjanUniversity in 2008. Two different plant nutrient including N and P and their combination (N+P were added to vinasse with three different concentrations to form experimental treatments. In addition to these treatments, three control treatments with vinasse of different concentrations, but with no additive were also included in the experiment. Each treatment used with two different application methods (soil application and soil + foliar application.The experiment had 24 treatments, a complete randomized design and three replications. The vinasse used in this experiment was diluted with water 10, 20 and 40 times to make a nutrient solution of three different concentrations of tomato plant. The amounts of nitrogen and phosphorus that were added to vinasse were 224 and 62 mg/l, respectively. Phosphorus and nitrogen were applied to as super-phosphate triple and calcium nitrate and ammonium nitrate respectively. After being deployed to ensure complete installation of tomatoes in pots containing perlite (about 2

Photoactive devices including porphyrinoids with coordinating additives

Science.gov (United States)

Forrest, Stephen R; Zimmerman, Jeramy; Yu, Eric K; Thompson, Mark E; Trinh, Cong; Whited, Matthew; Diev, Vlacheslav

2015-05-12

Coordinating additives are included in porphyrinoid-based materials to promote intermolecular organization and improve one or more photoelectric characteristics of the materials. The coordinating additives are selected from fullerene compounds and organic compounds having free electron pairs. Combinations of different coordinating additives can be used to tailor the characteristic properties of such porphyrinoid-based materials, including porphyrin oligomers. Bidentate ligands are one type of coordinating additive that can form coordination bonds with a central metal ion of two different porphyrinoid compounds to promote porphyrinoid alignment and/or pi-stacking. The coordinating additives can shift the absorption spectrum of a photoactive material toward higher wavelengths, increase the external quantum efficiency of the material, or both.

Effects of fire and nitrogen addition on forage quality of Aristida purpurea

Science.gov (United States)

Purple threeawn (Aristida purpurea Nutt.) is a native perennial bunchgrass with limited forage value that dominates sites with disturbed soils and persists with continued severe grazing. Fire and nitrogen addition have been used to reduce threeawn and may increase grazing utilization of threeawn by...

Divergent Effects of Nitrogen Addition on Soil Respiration in a Semiarid Grassland

OpenAIRE

Cheng Zhu; Yiping Ma; Honghui Wu; Tao Sun; Kimberly J. La Pierre; Zewei Sun; Qiang Yu

2016-01-01

Nitrogen (N) deposition has been steadily increasing for decades, with consequences for soil respiration. However, we have a limited understanding of how soil respiration responds to N availability. Here, we investigated the soil respiration responses to low and high levels of N addition (0.4?mol N m?2 yr?1 vs 1.6?mol N m?2 yr?1) over a two-year period in a semiarid Leymus chinensis grassland in Inner Mongolia, China. Our results show that low-level N addition increased soil respiration, plan...

Long-term nitrogen addition decreases carbon leaching in a nitrogen-rich forest ecosystem

Directory of Open Access Journals (Sweden)

X. Lu

2013-06-01

Full Text Available Dissolved organic carbon (DOC plays a critical role in the carbon (C cycle of forest soils, and has been recently connected with global increases in nitrogen (N deposition. Most studies on effects of elevated N deposition on DOC have been carried out in N-limited temperate regions, with far fewer data available from N-rich ecosystems, especially in the context of chronically elevated N deposition. Furthermore, mechanisms for excess N-induced changes of DOC dynamics have been suggested to be different between the two kinds of ecosystems, because of the different ecosystem N status. The purpose of this study was to experimentally examine how long-term N addition affects DOC dynamics below the primary rooting zones (the upper 20 cm soils in typically N-rich lowland tropical forests. We have a primary assumption that long-term continuous N addition minimally affects DOC concentrations and effluxes in N-rich tropical forests. Experimental N addition was administered at the following levels: 0, 50, 100 and 150 kg N ha−1 yr−1, respectively. Results showed that seven years of N addition significantly decreased DOC concentrations in soil solution, and chemo-physical controls (solution acidity change and soil sorption rather than biological controls may mainly account for the decreases, in contrast to other forests. We further found that N addition greatly decreased annual DOC effluxes from the primary rooting zone and increased water-extractable DOC in soils. Our results suggest that long-term N deposition could increase soil C sequestration in the upper soils by decreasing DOC efflux from that layer in N-rich ecosystems, a novel mechanism for continued accumulation of soil C in old-growth forests.

Ionic liquids, electrolyte solutions including the ionic liquids, and energy storage devices including the ionic liquids

Science.gov (United States)

Gering, Kevin L.; Harrup, Mason K.; Rollins, Harry W.

2015-12-08

An ionic liquid including a phosphazene compound that has a plurality of phosphorus-nitrogen units and at least one pendant group bonded to each phosphorus atom of the plurality of phosphorus-nitrogen units. One pendant group of the at least one pendant group comprises a positively charged pendant group. Additional embodiments of ionic liquids are disclosed, as are electrolyte solutions and energy storage devices including the embodiments of the ionic liquid.

Meta-analysis of high-latitude nitrogen-addition and warming studies imply ecological mechanisms overlooked by land models

Science.gov (United States)

Bouskill, N. J.; Riley, W. J.; Tang, J.

2014-08-01

Accurate representation of ecosystem processes in land models is crucial for reducing predictive uncertainty in energy and greenhouse gas feedbacks with the atmosphere. Here we describe an observational and modeling meta-analysis approach to benchmark land models, and apply the method to the land model CLM4.5 with two versions of belowground biogeochemistry. We focused our analysis on the above and belowground high-latitude ecosystem responses to warming and nitrogen addition, and identified mechanisms absent, or poorly parameterized in CLM4.5. While the two model versions predicted similar trajectories for soil carbon stocks following both types of perturbation, other variables (e.g., belowground respiration) differed from the observations in both magnitude and direction, indicating the underlying mechanisms are inadequate for representing high-latitude ecosystems. The observational synthesis attribute these differences to missing representations of microbial dynamics, characterization of above and belowground functional processes, and nutrient competition. We use the observational meta-analyses to discuss potential approaches to improving the current models (e.g., the inclusion of dynamic vegetation or different microbial functional guilds), however, we also raise a cautionary note on the selection of data sets and experiments to be included in a meta-analysis. For example, the concentrations of nitrogen applied in the synthesized field experiments (average =72 kg ha-1 yr-1) are many times higher than projected soil nitrogen concentrations (from nitrogen deposition and release during mineralization), which preclude a rigorous evaluation of the model responses to nitrogen perturbation. Overall, we demonstrate here that elucidating ecological mechanisms via meta-analysis can identify deficiencies in both ecosystem models and empirical experiments.

A test for clinal variation in Artemisia californica and associated arthropod responses to nitrogen addition.

Science.gov (United States)

Meza-Lopez, Maria M; Mooney, Kailen A; Thompson, Amanda L; Ho, Nicole K; Pratt, Jessica D

2018-01-01

The response of plant traits to global change is of fundamental importance to understanding anthropogenic impacts on natural systems. Nevertheless, little is known about plant genetic variation in such responses or the indirect effect of environmental change on higher trophic levels. In a three-year common garden experiment, we grew the shrub Artemisia californica from five populations sourced along a 700 km latitudinal gradient under ambient and nitrogen (N) addition (20 kg N ha-1) and measured plant traits and associated arthropods. N addition increased plant biomass to a similar extent among all populations. In contrast, N addition effects on most other plant traits varied among plant populations; N addition reduced specific leaf area and leaf percent N and increased carbon to nitrogen ratios in the two northern populations, but had the opposite or no effect on the three southern populations. N addition increased arthropod abundance to a similar extent among all populations in parallel with an increase in plant biomass, suggesting that N addition did not alter plant resistance to herbivores. N addition had no effect on arthropod diversity, richness, or evenness. In summary, genetic variation among A. californica populations mediated leaf-trait responses to N addition, but positive direct effects of N addition on plant biomass and indirect effects on arthropod abundance were consistent among all populations.

NOx formation from the combustion of monodisperse n-heptane sprays doped with fuel-nitrogen additives

Science.gov (United States)

Sarv, Hamid; Cernansky, Nicholas P.

1989-01-01

A series of experiments with simulated synthetic fuels were conducted in order to investigate the effect of droplet size on the conversion of fuel-nitrogen to NOx. Pyridine and pyrrole were added to n-heptane as nitrogen-containing additives and burned as monodisperse fuel droplets under various operating conditions in a spray combustion facility. The experimental results indicate that under stoichiometric and fuel-rich conditions, reducing the droplet size increases the efficiency of fuel-N conversion to NOx. This observation is associated with improved oxidation of the pyrolysis fragments of the additive by better oxygen penetration through the droplet flame zone. The dominant reactions by which fuel-N is transformed to NOx were also considered analytically by a premixed laminar flame code. The calculations are compared to the small droplet size results.

Quantifying nitrogen leaching response to fertilizer additions in China's cropland

International Nuclear Information System (INIS)

Gao, Shuoshuo; Xu, Peng; Zhou, Feng; Yang, Hui; Zheng, Chunmiao; Cao, Wei; Tao, Shu; Piao, Shilong; Zhao, Yue; Ji, Xiaoyan; Shang, Ziyin

2016-01-01

Agricultural soils account for more than 50% of nitrogen leaching (L_N) to groundwater in China. When excess levels of nitrogen accumulate in groundwater, it poses a risk of adverse health effects. Despite this recognition, estimation of L_N from cropland soils in a broad spatial scale is still quite uncertain in China. The uncertainty of L_N primarily stems from the shape of nitrogen leaching response to fertilizer additions (N_r_a_t_e) and the role of environmental conditions. On the basis of 453 site-years at 51 sites across China, we explored the nonlinearity and variability of the response of L_N to N_r_a_t_e and developed an empirical statistical model to determine how environmental factors regulate the rate of N leaching (LR). The result shows that L_N-N_r_a_t_e relationship is convex for most crop types, and varies by local hydro-climates and soil organic carbon. Variability of air temperature explains a half (∼52%) of the spatial variation of LR. The results of model calibration and validation indicate that incorporating this empirical knowledge into a predictive model could accurately capture the variation in leaching and produce a reasonable upscaling from site to country. The fertilizer-induced L_N in 2008 for China's cropland were 0.88 ± 0.23 TgN (1σ), significantly lower than the linear or uniform model, as assumed by Food and Agriculture Organization and MITERRA-EUROPE models. These results also imply that future policy to reduce N leaching from cropland needs to consider environmental variability rather than solely attempt to reduce N_r_a_t_e. - Highlights: • L_N-N_r_a_t_e relationship is convex and varies by local hydro-climates and SOC. • Variability of temperature explains a half of spatial variation of N leaching rate. • L_N in 2008 were 0.88 ± 0.23 Tg, lower than the linear or uniform models. • Reducing L_N should consider background rather than decreasing N_r_a_t_e solely. - Variability of air temperature explains a half of

Meta-analysis of high-latitude nitrogen-addition and warming studies implies ecological mechanisms overlooked by land models

Science.gov (United States)

Bouskill, N. J.; Riley, W. J.; Tang, J. Y.

2014-12-01

Accurate representation of ecosystem processes in land models is crucial for reducing predictive uncertainty in energy and greenhouse gas feedbacks with the climate. Here we describe an observational and modeling meta-analysis approach to benchmark land models, and apply the method to the land model CLM4.5 with two versions of belowground biogeochemistry. We focused our analysis on the aboveground and belowground responses to warming and nitrogen addition in high-latitude ecosystems, and identified absent or poorly parameterized mechanisms in CLM4.5. While the two model versions predicted similar soil carbon stock trajectories following both warming and nitrogen addition, other predicted variables (e.g., belowground respiration) differed from observations in both magnitude and direction, indicating that CLM4.5 has inadequate underlying mechanisms for representing high-latitude ecosystems. On the basis of observational synthesis, we attribute the model-observation differences to missing representations of microbial dynamics, aboveground and belowground coupling, and nutrient cycling, and we use the observational meta-analysis to discuss potential approaches to improving the current models. However, we also urge caution concerning the selection of data sets and experiments for meta-analysis. For example, the concentrations of nitrogen applied in the synthesized field experiments (average = 72 kg ha-1 yr-1) are many times higher than projected soil nitrogen concentrations (from nitrogen deposition and release during mineralization), which precludes a rigorous evaluation of the model responses to likely nitrogen perturbations. Overall, we demonstrate that elucidating ecological mechanisms via meta-analysis can identify deficiencies in ecosystem models and empirical experiments.

Decline of arbuscular mycorrhizal fungi in northern hardwood forests exposed to chronic nitrogen additions

Science.gov (United States)

Linda T.A. van Diepen; Erik A. Lilleskov; Kurt S. Pregitzer; R. Michael Miller

2007-01-01

Arbuscular mycorrhizal (AM) fungi are important below-ground carbon (C) sinks that can be sensitive to increased nitrogen (N) availability. The abundance of AM fungi (AMF) was estimated in maple (Acer spp.) fine roots following more than a decade of experimental additions of N designed to simulate chronic atmospheric N deposition.

Enhancement of biodegradation of crude petroleum-oil in contaminated water by the addition of nitrogen sources.

Science.gov (United States)

Mukred, A M; Hamid, A A; Hamzah, A; Yusoff, W M Wan

2008-09-01

Addition of nitrogen sources as supplementary nutrient into MSM medium to enhance biodegradation by stimulating the growth four isolates, Acinetobacter faecalis, Staphylococcus sp., Pseudomonas putida and Neisseria elongata isolated from petroleum contaminated groundwater, wastewater aeration pond and biopond at the oil refinery Terengganu Malaysia was investigated. The organic nitrogen sources tested not only supported growth but also enhances biodegradation of 1% Tapis crude oil. All four isolates showed good growth especially when peptone was employed as the organic nitrogen compared to growth in the basal medium. Gas chromatography showed that more then 91, 93, 94 and 95% degradation of total hydrocarbon was observed after 5 days of incubation by isolates Pseudomonas putida, Neisseria elongate, Acinetobacter faecalis and Staphylococcus sp., respectively.

RESPONSE OF SOIL MICROBIAL BIOMASS AND COMMUNITY COMPOSITION TO CHRONIC NITROGEN ADDITIONS AT HARVARD FOREST

Science.gov (United States)

Soil microbial communities may respond to anthropogenic increases in ecosystem nitrogen (N) availability, and their response may ultimately feedback on ecosystem carbon and N dynamics. We examined the long-term effects of chronic N additions on soil microbes by measuring soil mi...

Nitrapyrin addition mitigates nitrous oxide emissions and raises nitrogen use efficiency in plastic-film-mulched drip-fertigated cotton field.

Science.gov (United States)

Liu, Tao; Liang, Yongchao; Chu, Guixin

2017-01-01

Nitrification inhibitors (NIs) have been used extensively to reduce nitrogen losses and increase crop nitrogen nutrition. However, information is still scant regarding the influence of NIs on nitrogen transformation, nitrous oxide (N2O) emission and nitrogen utilization in plastic-film-mulched calcareous soil under high frequency drip-fertigated condition. Therefore, a field trial was conducted to evaluate the effect of nitrapyrin (2-chloro-6-(trichloromethyl)-pyridine) on soil mineral nitrogen (N) transformation, N2O emission and nitrogen use efficiency (NUE) in a drip-fertigated cotton-growing calcareous field. Three treatments were established: control (no N fertilizer), urea (225 kg N ha-1) and urea+nitrapyrin (225 kg N ha-1+2.25 kg nitrapyrin ha-1). Compared with urea alone, urea plus nitrapyrin decreased the average N2O emission fluxes by 6.6-21.8% in June, July and August significantly in a drip-fertigation cycle. Urea application increased the seasonal cumulative N2O emission by 2.4 kg N ha-1 compared with control, and nitrapyrin addition significantly mitigated the seasonal N2O emission by 14.3% compared with urea only. During the main growing season, the average soil ammonium nitrogen (NH4+-N) concentration was 28.0% greater and soil nitrate nitrogen (NO3--N) concentration was 13.8% less in the urea+nitrapyrin treatment than in the urea treatment. Soil NO3--N and water-filled pore space (WFPS) were more closely correlated than soil NH4+-N with soil N2O fluxes under drip-fertigated condition (Puse efficiency by 10.7%. The results demonstrated that nitrapyrin addition significantly inhibited soil nitrification and maintained more NH4+-N in soil, mitigated N2O losses and improved nitrogen use efficiency in plastic-film-mulched calcareous soil under high frequency drip-fertigated condition.

Reassessing carbon sequestration in the North China Plain via addition of nitrogen

Energy Technology Data Exchange (ETDEWEB)

Dong, Wenxu, E-mail: dongwx@sjziam.ac.cn [Key Laboratory of Agricultural Water Resources, Center for Agricultural Resources Research, Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, Shijiazhuang 050021 (China); Duan, Yongmei, E-mail: 106086193@QQ.com [Geological Survey of Jiangxi Province, Nanchang 330030 (China); Wang, Yuying, E-mail: wangyy@sjziam.ac.cn [Key Laboratory of Agricultural Water Resources, Center for Agricultural Resources Research, Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, Shijiazhuang 050021 (China); Hu, Chunsheng, E-mail: cshu@sjziam.ac.cn [Key Laboratory of Agricultural Water Resources, Center for Agricultural Resources Research, Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, Shijiazhuang 050021 (China)

2016-09-01

Soil inorganic carbon (SIC) exerts a strong influence on the carbon (C) sequestered in response to nitrogen (N) additions in arid and semi-arid ecosystems, but limited information is available on in situ SIC storage and dissolution at the field level. This study determined the soil organic/inorganic carbon storage in the soil profile at 0–100 cm depths and the concentration of dissolved inorganic carbon (DIC) in soil leachate in 4 N application treatments (0, 200, 400, and 600 kg N ha{sup −1} yr{sup −1}) for 15 years in the North China Plain. The objectives were to evaluate the effect of nitrogen fertilizer on total amount of carbon sequestration and the uptake of atmospheric CO{sub 2} in an agricultural system. Results showed that after 15 years of N fertilizer application the SOC contents at depths of 0–100 cm significantly increased, whereas the SIC contents significantly decreased at depths of 0–60 cm. However, the actual measured loss of carbonate was far higher than the theoretical maximum values of dissolution via protons from nitrification. Furthermore, the amount of HCO{sub 3}{sup −} and the HCO{sub 3}{sup −} / (Ca{sup 2+} + Mg{sup 2+}) ratio in soil leachate were higher in the N application treatments than no fertilizer input (CK) for the 0–80 cm depth. The result suggested that the dissolution of carbonate was mainly enhanced by soil carbonic acid, a process which can absorb soil or atmosphere CO{sub 2} and less influenced by protons through the nitrification which would release CO{sub 2}. To accurately evaluate soil C sequestration under N input scenarios in semi-arid regions, future studies should include both changes in SIC storage as well as the fractions of dissolution with different sources of acids in soil profiles. - Highlights: • The SOC contents significantly increased after long-term nitrogen application, while SIC decreased. • The measured loss of carbonate was far higher than the theoretical values of dissolution from

Sediment diatom species and community response to nitrogen addition in Oregon (USA) estuarine tidal wetlands

Science.gov (United States)

Sediment microalgae play an important role in nutrient cycling and are important primary producers in the food web in Pacific Northwest estuaries. This study examines the effects of nitrogen addition to benthic microalgae in tidal wetlands of Yaquina Bay estuary on the Oregon c...

Response of Functional Structure of Soil Microbial Community to Multi-level Nitrogen Additions on the Central Tibetan Plateau

Science.gov (United States)

Zhang, G.; Yuan, Y.

2015-12-01

The use of fossil fuels and fertilizers has increased the amount of biologically reactive nitrogen in the atmosphere over the past century. Tibet is the one of the most threatened regions by nitrogen deposition, thus understanding how its microbial communities function maybe of high importance to predicting microbial responses to nitrogen deposition. Here we describe a short-time nitrogen addition conducted in an alpine steppe ecosystem to investigate the response of functional structure of soil microbial community to multi-level nitrogen addition. Using a GeoChip 4.0, we showed that functional diversities and richness of functional genes were unchanged at low level of nitrogen fertilizer inputs (=40 kg N ha-1 yr-1). Detrended correspondence analysis indicated that the functional structure of microbial communities was markedly different across the nitrogen gradients. Most C degradation genes whose abundances significantly increased under elevated N fertilizer were those involved in the degradation of relatively labile C (starch, hemicellulose, cellulose), whereas the abundance of certain genes involved in the degradation of recalcitrant C (i.e. lignin) was largely decreased (such as manganese peroxidase, mnp). The results suggest that the elevated N fertilization rates might significantly accelerate the labile C degradation, but might not spur recalcitrant C degradation. The combined effect of gdh and ureC genes involved in N cycling appeared to shift the balance between ammonia and organic N toward organic N ammonification and hence increased the N mineralization potential. Moreover, Urease directly involved in urea mineralization significantly increased. Lastly, Canonical correspondence analysis showed that soil (TOC+NH4++NO3-+NO2-+pH) and plant (Aboveground plant productivity + Shannon Diversity) variables could explain 38.9% of the variation of soil microbial community composition. On the basis of above observations, we predict that increasing of nitrogen

Nitrogen

Science.gov (United States)

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.

Effects of biochar addition to soil on nitrogen fluxes in a winter wheat lysimeter experiment

Science.gov (United States)

Hüppi, Roman; Leifeld, Jens; Neftel, Albrecht; Conen, Franz; Six, Johan

2014-05-01

Biochar is a carbon-rich, porous residue from pyrolysis of biomass that potentially increases crop yields by reducing losses of nitrogen from soils and/or enhancing the uptake of applied fertiliser by the crops. Previous research is scarce about biochar's ability to increase wheat yields in temperate soils or how it changes nitrogen dynamics in the field. In a lysimeter system with two different soils (sandy/silt loam) nitrogen fluxes were traced by isotopic 15N enriched fertiliser to identify changes in nitrous oxide emissions, leaching and plant uptake after biochar addition. 20t/ha woodchip-waste biochar (pH=13) was applied to these soils in four lysimeters per soil type; the same number of lysimeters served as a control. The soils were cropped with winter wheat during the season 2012/2013. 170 kg-N/ha ammonium nitrate fertiliser with 10% 15N was applied in 3 events during the growing season and 15N concentrations where measured at different points in time in plant, soil, leachate and emitted nitrous oxide. After one year the lysimeter system showed no difference between biochar and control treatment in grain- and straw yield or nitrogen uptake. However biochar did reduce nitrous oxide emissions in the silt loam and losses of nitrate leaching in sandy loam. This study indicates potential reduction of nitrogen loss from cropland soil by biochar application but could not confirm increased yields in an intensive wheat production system.

Leaf nitrogen assimilation and partitioning differ among subtropical forest plants in response to canopy addition of nitrogen treatments

Science.gov (United States)

Nan Liu; Shuhua Wu; Qinfeng Guo; Jiaxin Wang; Ce Cao; Jun Wang

2018-01-01

Global increases in nitrogen deposition may alter forest structure and function by interferingwith plant nitrogen metabolism (e.g., assimilation and partitioning) and subsequent carbon assimilation, but it is unclear how these responses to nitrogen deposition differ among species. In this study, we conducted a 2-year experiment to investigate the effects of canopy...

Effects of phosphorus and nitrogen additions on tropical soil microbial activity in the context of experimental warming

Science.gov (United States)

Foley, M.; Nottingham, A.; Turner, B. L.

2017-12-01

Soil warming is generally predicted to increase microbial mineralization rates and accelerate soil C losses which could establish a positive feedback to climatic warming. Tropical rain forests account for a third of global soil C, yet the responseto of tropical soil C a warming climate remains poorly understood. Despite predictions of soil C losses, decomposition of soil organic matter (SOM) in tropical soils may be constrained by several factors including microbial nutrient deficiencies. We performed an incubation experiment in conjunction with an in-situ soil warming experiment in a lowland tropical forest on Barro Colorado Island, Panama, to measure microbial response to two key nutrient additions in shallow (0-10cm) and deep (50-100 cm) soils. We compared the response of lowland tropical soils to montane tropical soils, predicting that lowland soils would display the strongest response to phosphorus additions. Soils were treated with either carbon alone (C), nitrogen (CN), phosphorus (CP) or nitrogen and phosphorus combined (CNP). Carbon dioxide (CO2) production was measured by NaOH capture and titrimetric analysis for 10 days. Cumulative CO2 production in montane soils increased significantly with all additions, suggesting these soils are characterized by a general microbial nutrient deficiency. The cumulative amount of C respired in deep soils from the lowland site increased significantly with CP and CNP additions, suggesting that microbial processes in deep lowland tropical soils are phosphorus-limited. These results support the current understanding that lowland tropical forests are growing on highly weathered, phosphorus-deplete soils, and provide novel insight that deep tropical SOM may be stabilized by a lack of biologically-available phosphorus. Further, this data suggests tropical soil C losses under elevated temperature may be limited by a strong microbial phosphorus deficiency.

Challenges of including nitrogen effects on decomposition in earth system models

Science.gov (United States)

Hobbie, S. E.

2011-12-01

Despite the importance of litter decomposition for ecosystem fertility and carbon balance, key uncertainties remain about how this fundamental process is affected by nitrogen (N) availability. Nevertheless, resolving such uncertainties is critical for mechanistic inclusion of such processes in earth system models, towards predicting the ecosystem consequences of increased anthropogenic reactive N. Towards that end, we have conducted a series of experiments examining nitrogen effects on litter decomposition. We found that both substrate N and externally supplied N (regardless of form) accelerated the initial decomposition rate. Faster initial decomposition rates were linked to the higher activity of carbohydrate-degrading enzymes associated with externally supplied N and the greater relative abundances of Gram negative and Gram positive bacteria associated with green leaves and externally supplied organic N (assessed using phospholipid fatty acid analysis, PLFA). By contrast, later in decomposition, externally supplied N slowed decomposition, increasing the fraction of slowly decomposing litter and reducing lignin-degrading enzyme activity and relative abundances of Gram negative and Gram positive bacteria. Our results suggest that elevated atmospheric N deposition may have contrasting effects on the dynamics of different soil carbon pools, decreasing mean residence times of active fractions comprising very fresh litter, while increasing those of more slowly decomposing fractions including more processed litter. Incorporating these contrasting effects of N on decomposition processes into models is complicated by lingering uncertainties about how these effects generalize across ecosystems and substrates.

The effects of warming and nitrogen addition on soil nitrogen cycling in a temperate grassland, northeastern China.

Directory of Open Access Journals (Sweden)

Lin-Na Ma

Full Text Available Both climate warming and atmospheric nitrogen (N deposition are predicted to affect soil N cycling in terrestrial biomes over the next century. However, the interactive effects of warming and N deposition on soil N mineralization in temperate grasslands are poorly understood.A field manipulation experiment was conducted to examine the effects of warming and N addition on soil N cycling in a temperate grassland of northeastern China from 2007 to 2009. Soil samples were incubated at a constant temperature and moisture, from samples collected in the field. The results showed that both warming and N addition significantly stimulated soil net N mineralization rate and net nitrification rate. Combined warming and N addition caused an interactive effect on N mineralization, which could be explained by the relative shift of soil microbial community structure because of fungal biomass increase and strong plant uptake of added N due to warming. Irrespective of strong intra- and inter-annual variations in soil N mineralization, the responses of N mineralization to warming and N addition did not change during the three growing seasons, suggesting independence of warming and N responses of N mineralization from precipitation variations in the temperate grassland.Interactions between climate warming and N deposition on soil N cycling were significant. These findings will improve our understanding on the response of soil N cycling to the simultaneous climate change drivers in temperate grassland ecosystem.

84 K nitrogen system for the SSC

International Nuclear Information System (INIS)

McAshan, M.; Thirumaleshwar, M.; Abramovich, S.; Ganni, V.; Scheidemantle, A.

1992-01-01

The nitrogen system for the Superconducting Super Collider (SSC) is designed to provide the 84 K (nominal) shield refrigeration for the collider rings. Liquid nitrogen is supplied to the collider tunnel from one, two, or more locations on the surface through the service shafts and is distributed along, the 87 km of both rings by the 84 K shield lines. Additional design requirements for the nitrogen distribution system include precooling, fluid supply to the helium plants, supplying makeup liquid nitrogen to the reservoirs located at the entrance of the main shafts, and providing an efficient cooldown means for the cold mass from 300 K to 90 K. The operational modes and possible emergency and maintenance conditions of the collider are taken into account for the nitrogen system design. The status of our work, including design considerations that address thermal aspects (heat load, recooling scheme, etc.) and hydraulic aspects (pressures, elevations, distances, etc.) of the nitrogen system will be discussed

Stimulation of terrestrial ecosystem carbon storage by nitrogen addition: a meta-analysis.

Science.gov (United States)

Yue, Kai; Peng, Yan; Peng, Changhui; Yang, Wanqin; Peng, Xin; Wu, Fuzhong

2016-01-27

Elevated nitrogen (N) deposition alters the terrestrial carbon (C) cycle, which is likely to feed back to further climate change. However, how the overall terrestrial ecosystem C pools and fluxes respond to N addition remains unclear. By synthesizing data from multiple terrestrial ecosystems, we quantified the response of C pools and fluxes to experimental N addition using a comprehensive meta-analysis method. Our results showed that N addition significantly stimulated soil total C storage by 5.82% ([2.47%, 9.27%], 95% CI, the same below) and increased the C contents of the above- and below-ground parts of plants by 25.65% [11.07%, 42.12%] and 15.93% [6.80%, 25.85%], respectively. Furthermore, N addition significantly increased aboveground net primary production by 52.38% [40.58%, 65.19%] and litterfall by 14.67% [9.24%, 20.38%] at a global scale. However, the C influx from the plant litter to the soil through litter decomposition and the efflux from the soil due to microbial respiration and soil respiration showed insignificant responses to N addition. Overall, our meta-analysis suggested that N addition will increase soil C storage and plant C in both above- and below-ground parts, indicating that terrestrial ecosystems might act to strengthen as a C sink under increasing N deposition.

Effects of additive application upon ad libitum intake, in vivo digestibility and nitrogen balance of alfalfa haylage

Directory of Open Access Journals (Sweden)

Mladen Knežević

2009-09-01

Full Text Available The research objective was to determine the effect of the additive Sill-All application on ad libitum intake, in vivo digestibility and nitrogen balance of alfalfa haylage. About 40 % alfalfa plants was ensiled at the phonological flowering stage into plastic foil-wrapped bales without or with additive (2 L t-1 plant mass. No statistically significant differences were found between alfalfa ensiled without additive and alfalfa ensiled with additive for the content of dry matter (DM (632 g and 631 g DM kg-1 fresh sample, respectively. Alfalfa ensiled without additive contained 921 g organic matter (OM kg-1 DM, which was significantly higher (P<0.001 compared to alfalfa ensiled with additive (902 g OM kg-1 DM. Alfalfa ensiled without additive contained 141 g crude proteins (CP kg-1 DM, which was significantly higher (P<0.001 compared to alfalfa ensiled with additive (139 g CP kg-1 DM. Alfalfa ensiled with additive contained significantly less acid detergent fibers (ADF (P<0.001 compared to alfalfa ensiled without additive (445 g kg-1 DM and 456 g kg-1 DM, respectively and had a lower pH value (P<0.001 (5.29 and 5.56, respectively. No statistically significant differences were found between the studied feeding treatments for ad libitum intake of fresh ration and DM ration, for the measured parameters of digestibility and N balance. It was concluded that addition of the additive to alfalfa haylage led to significant changes in chemical composition; however, changes in chemical composition had no impact on measured biological parameters (ad libitum intake, in vivo digestibility and nitrogen balance.

Effects of hydrogen addition and nitrogen dilution on the laminar flame characteristics of premixed methane-air flames

Energy Technology Data Exchange (ETDEWEB)

Tahtouh, T.; Halter, F.; Mounaim-Rousselle, C. [Institut PRISME, Universite d' Orleans, 8 rue Leonard de Vinci-45072, Orleans Cedex 2 (France); Samson, E. [PSA Peugeot Citroen (France)

2009-10-15

The effect of hydrogen addition and nitrogen dilution on laminar flame characteristics was investigated. The spherical expanding flame technique, in a constant volume bomb, was employed to extract laminar flame characteristics. The mole fraction of hydrogen in the methane-hydrogen mixture was varied from 0 to 1 and the mole fraction of nitrogen in the total mixture (methane-hydrogen-air-diluent) from 0 to 0.35. Measurements were performed at an initial pressure of 0.1 MPa and an initial temperature of 300 K. The mixtures investigated were under stoichiometric conditions. Based on experimental measurements, a new correlation for calculating the laminar burning velocity of methane-hydrogen-air-nitrogen mixtures is proposed. The laminar burning velocity was found to increase linearly with hydrogen mass fraction for all dilution ratios while the burned gas Markstein length decreases with the increase in hydrogen amount in the mixture except for high hydrogen mole fractions (>0.6). Nitrogen dilution has a nonlinear reducing effect on the laminar burning velocity and an increasing effect on the burned gas Markstein length. The experimental results and the proposed correlation obtained are in good agreement with literature values. (author)

Effects of nitrogen and phosphorus additions on soil microbial biomass and community structure in two reforested tropical forests.

Science.gov (United States)

Liu, Lei; Gundersen, Per; Zhang, Wei; Zhang, Tao; Chen, Hao; Mo, Jiangming

2015-09-23

Elevated nitrogen (N) deposition may aggravate phosphorus (P) deficiency in forests in the warm humid regions of China. To our knowledge, the interactive effects of long-term N deposition and P availability on soil microorganisms in tropical replanted forests remain unclear. We conducted an N and P manipulation experiment with four treatments: control, N addition (15 g N m(-2)·yr(-1)), P addition (15 g P m(-2)·yr(-1)), and N and P addition (15 + 15 g N and P m(-2)·yr(-1), respectively) in disturbed (planted pine forest with recent harvests of understory vegetation and litter) and rehabilitated (planted with pine, but mixed with broadleaf returning by natural succession) forests in southern China. Nitrogen addition did not significantly affect soil microbial biomass, but significantly decreased the abundance of gram-negative bacteria PLFAs in both forest types. Microbial biomass increased significantly after P addition in the disturbed forest but not in the rehabilitated forest. No interactions between N and P additions on soil microorganisms were observed in either forest type. Our results suggest that microbial growth in replanted forests of southern China may be limited by P rather than by N, and this P limitation may be greater in disturbed forests.

Nutrient additions in pristine Patagonian Sphagnum bog vegetation : can phosphorus addition alleviate (the effects of) increased nitrogen loads

NARCIS (Netherlands)

Fritz, C.; Dijk, G. van; Smolders, A.J.P.; Pancotto, V.A.; Elzenga, J.T.M.; Roelofs, J.G.M.; Grootjans, A.P.

Sphagnum-bog ecosystems have a limited capability to retain carbon and nutrients when subjected to increased nitrogen (N) deposition. Although it has been proposed that phosphorus (P) can dilute negative effects of nitrogen by increasing biomass production of Sphagnum mosses, it is still unclear

Ubiquity of insect-derived nitrogen transfer to plants by endophytic insect-pathogenic fungi: an additional branch of the soil nitrogen cycle.

Science.gov (United States)

Behie, Scott W; Bidochka, Michael J

2014-03-01

The study of symbiotic nitrogen transfer in soil has largely focused on nitrogen-fixing bacteria. Vascular plants can lose a substantial amount of their nitrogen through insect herbivory. Previously, we showed that plants were able to reacquire nitrogen from insects through a partnership with the endophytic, insect-pathogenic fungus Metarhizium robertsii. That is, the endophytic capability and insect pathogenicity of M. robertsii are coupled so that the fungus acts as a conduit to provide insect-derived nitrogen to plant hosts. Here, we assess the ubiquity of this nitrogen transfer in five Metarhizium species representing those with broad (M. robertsii, M. brunneum, and M. guizhouense) and narrower insect host ranges (M. acridum and M. flavoviride), as well as the insect-pathogenic fungi Beauveria bassiana and Lecanicillium lecanii. Insects were injected with (15)N-labeled nitrogen, and we tracked the incorporation of (15)N into two dicots, haricot bean (Phaseolus vulgaris) and soybean (Glycine max), and two monocots, switchgrass (Panicum virgatum) and wheat (Triticum aestivum), in the presence of these fungi in soil microcosms. All Metarhizium species and B. bassiana but not L. lecanii showed the capacity to transfer nitrogen to plants, although to various degrees. Endophytic association by these fungi increased overall plant productivity. We also showed that in the field, where microbial competition is potentially high, M. robertsii was able to transfer insect-derived nitrogen to plants. Metarhizium spp. and B. bassiana have a worldwide distribution with high soil abundance and may play an important role in the ecological cycling of insect nitrogen back to plant communities.

Multi-stage combustion using nitrogen-enriched air

Science.gov (United States)

Fischer, Larry E.; Anderson, Brian L.

2004-09-14

Multi-stage combustion technology combined with nitrogen-enriched air technology for controlling the combustion temperature and products to extend the maintenance and lifetime cycles of materials in contact with combustion products and to reduce pollutants while maintaining relatively high combustion and thermal cycle efficiencies. The first stage of combustion operates fuel rich where most of the heat of combustion is released by burning it with nitrogen-enriched air. Part of the energy in the combustion gases is used to perform work or to provide heat. The cooled combustion gases are reheated by additional stages of combustion until the last stage is at or near stoichiometric conditions. Additional energy is extracted from each stage to result in relatively high thermal cycle efficiency. The air is enriched with nitrogen using air separation technologies such as diffusion, permeable membrane, absorption, and cryogenics. The combustion method is applicable to many types of combustion equipment, including: boilers, burners, turbines, internal combustion engines, and many types of fuel including hydrogen and carbon-based fuels including methane and coal.

Effect of the addition of nitrogen sources to cassava fiber and carbon-to-nitrogen ratios on Agaricus brasiliensis growth.

Science.gov (United States)

Mantovani, T R D; Linde, G A; Colauto, N B

2007-01-01

The same substratum formulation to grow Agaricus bisporus has been used to grow Agaricus brasiliensis since its culture started in Brazil. Despite being different species, many of the same rules have been used for composting or axenic cultivation when it comes to nitrogen content and source in the substrate. The aim of this study was to verify the mycelial growth of A. brasiliensis in different ammonium sulfate and (or) urea concentrations added to cassava fiber and different carbon-to-nitrogen (C:N) ratios to increase the efficiency of axenic cultivation. Two nitrogen sources (urea and (or) ammonium sulfate) added to cassava fiber were tested for the in vitro mycelial growth in different C:N ratios (ranging from 2.5:l to 50:l) in the dark at 28 degrees C. The radial mycelial growth was measured after 8 days of growth and recorded photographically at the end of the experiment. Nitrogen from urea enhanced fungal growth better than ammonium sulfate or any mixture of nitrogen. The best C:N ratios for fungal growth were from 10:l to 50:l; C:N ratios below 10:l inhibited fungal growth.

A Comparative Density Functional Theory and Density Functional Tight Binding Study of Phases of Nitrogen Including a High Energy Density Material N8

Directory of Open Access Journals (Sweden)

Nicholas Capel

2015-11-01

Full Text Available We present a comparative dispersion-corrected Density Functional Theory (DFT and Density Functional Tight Binding (DFTB-D study of several phases of nitrogen, including the well-known alpha, beta, and gamma phases as well as recently discovered highly energetic phases: covalently bound cubic gauche (cg nitrogen and molecular (vdW-bound N8 crystals. Among several tested parametrizations of N–N interactions for DFTB, we identify only one that is suitable for modeling of all these phases. This work therefore establishes the applicability of DFTB-D to studies of phases, including highly metastable phases, of nitrogen, which will be of great use for modelling of dynamics of reactions involving these phases, which may not be practical with DFT due to large required space and time scales. We also derive a dispersion-corrected DFT (DFT-D setup (atom-centered basis parameters and Grimme dispersion parameters tuned for accurate description simultaneously of several nitrogen allotropes including covalently and vdW-bound crystals and including high-energy phases.

Long-term nitrogen additions and the intrinsic water-use efficiency of boreal Scots pine.

Science.gov (United States)

Marshall, John; Wallin, Göran; Linder, Sune; Lundmark, Tomas; Näsholm, Torgny

2015-04-01

Nitrogen fertilization nearly always increases productivity in boreal forests, at least in terms of wood production, but it is unclear how. In a mature (80 yrs. old) Scots pine forest in northern Sweden, we tested the extent to which nitrogen fertilization increased intrinsic photosynthetic water-use efficiency. We measured δ13C both discretely, in biweekly phloem sampling, and continuously, by monitoring of bole respiration. The original experiment was designed as a test of eddy covariance methods and is not therefore strictly replicated. Nonetheless, we compared phloem contents among fifteen trees from each plot and stem respiration from four per plot. The treatments included addition of 100 kg N/ha for eight years and a control. Phloem contents have the advantage of integrating over the whole canopy and undergoing complete and rapid turnover. Their disadvantage is that some have observed isotopic drift with transport down the length of the stem, presumably as a result of preferential export and/or reloading. We also measured the isotopic composition of stem respiration from four trees on each plot using a Picarro G1101-I CRDS attached to the vent flow from a continuous gas-exchange system. We detected consistent differences in δ13C between the treatments in phloem contents. Within each treatment, the phloem δ13C was negatively correlated with antecedent temperature (R2= 0.65) and no other measured climate variable. The isotopic composition of stem CO2 efflux will be compared to that of phloem contents. However, when converted to intrinsic water-use efficiency, the increase amounted to only about 4%. This is a small relative to the near doubling in wood production. Although we were able to detect a clear and consistent increase in water-use efficiency with N-fertilization, it constitutes but a minor cause of the observed increase in wood production.

Effect of nitrogen addition on the performance of microbial fuel cell anodes

KAUST Repository

Saito, Tomonori

2011-01-01

Carbon cloth anodes were modified with 4(N,N-dimethylamino)benzene diazonium tetrafluoroborate to increase nitrogen-containing functional groups at the anode surface in order to test whether the performance of microbial fuel cells (MFCs) could be improved by controllably modifying the anode surface chemistry. Anodes with the lowest extent of functionalization, based on a nitrogen/carbon ratio of 0.7 as measured by XPS, achieved the highest power density of 938mW/m2. This power density was 24% greater than an untreated anode, and similar to that obtained with an ammonia gas treatment previously shown to increase power. Increasing the nitrogen/carbon ratio to 3.8, however, decreased the power density to 707mW/m2. These results demonstrate that a small amount of nitrogen functionalization on the carbon cloth material is sufficient to enhance MFC performance, likely as a result of promoting bacterial adhesion to the surface without adversely affecting microbial viability or electron transfer to the surface. © 2010 Elsevier Ltd.

Improvement in the long term creep rupture strength of SUS 316 steel for fast breeder reactors by nitrogen addition

International Nuclear Information System (INIS)

Nakazawa, Takanori; Abo, Hideo; Tanino, Mitsuru; Komatsu, Hazime; Tashimo, Masanori; Nishida, Takashi.

1989-01-01

Improvement of creep fatigue property of structural materials for fast breeder reactors. In order to improve the resistance to creep fatigue of SUS 316 steels, the effects of nitrogen, carbon, and molybdenum on creep properties have been investigated, under the concept that creep fatigue endurance is correspond to creep rupture ductility. Creep rupture tests and slow strain rate tensile tests were conducted at 550degC and extensive microstructural works were performed. The strengthening by nitrogen is much greater than carbon. Moreover, while carbon reduces rupture ductility, nitrogen does not change it. The addition of carbon results in coarse carbide formation on grain boundaries during creep, but with nitrogen very fine Fe 2 Mo particles precipitate on grain boundaries. The difference between the effects of nitrogen and carbon on creep properties is arise from the different morphology of precipitation. Strengthening by molybdenum brings about a slight decrease in rupture ductility. On the basis of these results, 0.01%C-0.07%N-11%Ni-16.5%Cr-2%Mo steel is selected as a promising material for fast breeder reactors. This steel has higher rupture ductility and strength than SUS 316 steel. It is also confirmed that this steel has a higher resistance to creep fatigue. (author)

The response of heterotrophic activity and carbon cycling to nitrogen additions and warming in two tropical soils

Science.gov (United States)

Daniela F. Cusack; Margaret S. Torn; William H. McDowell; Whendee L. Silver

2010-01-01

Nitrogen (N) deposition is projected to increase significantly in tropical regions in the coming decades, where changes in climate are also expected. Additional N and warming each have the potential to alter soil carbon (C) storage via changes in microbial activity and decomposition, but little is known about the combined effects of these global change factors in...

Nitrogen biogeochemistry in the oligohaline zone of a New England estuary

Energy Technology Data Exchange (ETDEWEB)

Holmes, R.M.; Peterson, B.J.; Deegan, L.A.; Hughes, J.E.; Fry, B.

2000-02-01

The authors investigated nitrogen cycling in the oligohaline zone of the Parker River estuary in northeastern Massachusetts. They introduced an isotopic tracer ({sup 15}N-NO{sub 3}{sup {minus}}) for 27 days in August 1996 to help determine how watershed-derived nitrogen moves through the upper estuary. The amount of tracer added was sufficient to enrich nitrate isotopically by {approximately}100% in the vicinity of the addition but did not influence nitrate concentration appreciably. During typical summer low-flow conditions as occurred during the addition period, essentially all riverine nitrate (including the nitrate tracer) was rapidly removed from the water column by the planktonic diatom Actinocyclus normanii. Export of tracer down-estuary was low during the isotope addition period, in part because of low river discharge. Instead, most of the nitrogen originally assimilated by A. normanii was transferred to sediments in the oligohaline zone. Nitrogen demand by phytoplankton during summer exceeded riverine supply by an order of magnitude. The additional nitrogen came mainly from the regeneration of benthic nitrogen, although some may have come from groundwater. The whole-ecosystem isotope tracer approach applied here was a powerful means of investigating the fate of watershed-derived nitrogen in the upper estuary.

Nitrogen-Doped Graphene for Photocatalytic Hydrogen Generation.

Science.gov (United States)

Chang, Dong Wook; Baek, Jong-Beom

2016-04-20

Photocatalytic hydrogen (H2 ) generation in a water splitting process has recently attracted tremendous interest because it allows the direct conversion of clean and unlimited solar energy into the ideal energy resource of H2 . For efficient photocatalytic H2 generation, the role of the photocatalyst is critical. With increasing demand for more efficient, sustainable, and cost-effective photocatalysts, various types of semiconductor photocatalysts have been intensively developed. In particular, on the basis of its superior catalytic and tunable electronic properties, nitrogen-doped graphene is a potential candidate for a high-performance photocatalyst. Nitrogen-doped graphene also offers additional advantages originating from its unique two-dimensional sp(2) -hybridized carbon network including a large specific surface area and exceptional charge transport properties. It has been reported that nitrogen-doped graphene can play diverse but positive functions including photo-induced charge acceptor/meditator, light absorber from UV to visible light, n-type semiconductor, and giant molecular photocatalyst. Herein, we summarize the recent progress and general aspects of nitrogen-doped graphene as a photocatalyst for photocatalytic H2 generation. In addition, challenges and future perspectives in this field are also discussed. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Transformation of fertilizer nitrogen in soil

International Nuclear Information System (INIS)

Soechting, H.

1980-01-01

Pot experiments are described in which the transformations between nitrogen added as fertilizer urea, plant-assimilated nitrogen, and different chemical fractions of soil or added straw nitrogen were studied with 15 N as a tracer. The data indicated that: (a) The transformation of added fertilizer nitrogen to immobilized amide nitrogen is decreased with added decomposable organic carbon. The transformation to immobilized α-amino N is increased, on the other hand, by the addition of decomposable organic carbon. (b) The freshly immobilized amide nitrogen is more readily remineralized than the α-amino form. The immobilization of added nitrogen continues in the presence of growing plants. (c) Mineralization of nitrogen added as 15 N-labelled straw is also increased with increasing fertilizer-nitrogen additions. (author)

The influence of sterilization on nitrogen-included ultrananocrystalline diamond for biomedical applications

International Nuclear Information System (INIS)

Tong, Wei; Tran, Phong A.; Turnley, Ann M.; Aramesh, Morteza; Prawer, Steven; Brandt, Milan; Fox, Kate

2016-01-01

Diamond has shown great potential in different biomedical applications, but the effects of sterilization on its properties have not been investigated. Here, we studied the influence of five sterilization techniques (solvent cleaning, oxygen plasma, UV irradiation, autoclave and hydrogen peroxide) on nitrogen-included ultrananocrystalline diamond. The chemical modification of the diamond surface was evaluated using X-ray photoelectron spectroscopy and water contact angle measurements. Different degrees of surface oxidation and selective sp 2 bonded carbon etching were found following all sterilization techniques, resulting in an increase of hydrophilicity. Higher viabilities of in vitro mouse 3T3 fibroblasts and rat cortical neuron cells were observed on oxygen plasma, autoclave and hydrogen peroxide sterilized diamond, which correlated with their higher hydrophilicity. By examination of apatite formation in simulated body fluid, in vivo bioactivity was predicted to be best on those surfaces which have been oxygen plasma treated and lowest on those which have been exposed to UV irradiation. The charge injection properties were also altered by the sterilization process and there appears to be a correlation between these changes and the degree of oxygen termination of the surface. We find that the modification brought by autoclave, oxygen plasma and hydrogen peroxide were most consistent with the use of N-UNCD in biological applications as compared to samples sterilized by solvent cleaning or UV exposure or indeed non-sterilized. A two-step process of sterilization by hydrogen peroxide following oxygen plasma treatment was then suggested. However, the final choice of sterilization technique will depend on the intended end application. - Highlights: • We test for the first time the effect of 5 sterilization techniques on nitrogen included ultrananocrystalline diamond. • Different degrees of surface oxidation and selective sp 2 bonded carbon etching were found to

The influence of sterilization on nitrogen-included ultrananocrystalline diamond for biomedical applications

Energy Technology Data Exchange (ETDEWEB)

Tong, Wei [School of Physics, University of Melbourne, Parkville, Victoria (Australia); Tran, Phong A. [Department of Chemical and Biomolecular Engineering, University of Melbourne, Parkville, Victoria (Australia); Institute of Health and Biomedical Innovation, Queensland University of Technology, Kelvin Grove, Queensland (Australia); Turnley, Ann M. [Department of Anatomy and Neuroscience, University of Melbourne, Parkville, Victoria (Australia); Aramesh, Morteza [School of Physics, University of Melbourne, Parkville, Victoria (Australia); School of Chemistry, Physics, and Mechanical Engineering, Queensland University of Technology, Brisbane, Queensland (Australia); Prawer, Steven [School of Physics, University of Melbourne, Parkville, Victoria (Australia); Brandt, Milan [Centre for Additive Manufacturing, School of Aerospace, Mechanical and Manufacturing Engineering, RMIT University, Melbourne, Victoria (Australia); Fox, Kate, E-mail: kate.fox@rmit.edu.au [Centre for Additive Manufacturing, School of Aerospace, Mechanical and Manufacturing Engineering, RMIT University, Melbourne, Victoria (Australia)

2016-04-01

Diamond has shown great potential in different biomedical applications, but the effects of sterilization on its properties have not been investigated. Here, we studied the influence of five sterilization techniques (solvent cleaning, oxygen plasma, UV irradiation, autoclave and hydrogen peroxide) on nitrogen-included ultrananocrystalline diamond. The chemical modification of the diamond surface was evaluated using X-ray photoelectron spectroscopy and water contact angle measurements. Different degrees of surface oxidation and selective sp{sup 2} bonded carbon etching were found following all sterilization techniques, resulting in an increase of hydrophilicity. Higher viabilities of in vitro mouse 3T3 fibroblasts and rat cortical neuron cells were observed on oxygen plasma, autoclave and hydrogen peroxide sterilized diamond, which correlated with their higher hydrophilicity. By examination of apatite formation in simulated body fluid, in vivo bioactivity was predicted to be best on those surfaces which have been oxygen plasma treated and lowest on those which have been exposed to UV irradiation. The charge injection properties were also altered by the sterilization process and there appears to be a correlation between these changes and the degree of oxygen termination of the surface. We find that the modification brought by autoclave, oxygen plasma and hydrogen peroxide were most consistent with the use of N-UNCD in biological applications as compared to samples sterilized by solvent cleaning or UV exposure or indeed non-sterilized. A two-step process of sterilization by hydrogen peroxide following oxygen plasma treatment was then suggested. However, the final choice of sterilization technique will depend on the intended end application. - Highlights: • We test for the first time the effect of 5 sterilization techniques on nitrogen included ultrananocrystalline diamond. • Different degrees of surface oxidation and selective sp{sup 2} bonded carbon etching were

Total Nitrogen Deposition (wet+dry) from the Atmosphere

Data.gov (United States)

U.S. Environmental Protection Agency — Oxides of Nitrogen are emitted primarily as by-products of combustion. Sources include power plants, industrial boilers, and automobiles. In addition, agricultural...

Nitrogen Control in VIM Melts

Science.gov (United States)

Jablonski, P. D.; Hawk, J. A.

NETL has developed a design and control philosophy for the addition of nitrogen to austenitic and ferritic steels. The design approach uses CALPHAD as the centerpiece to predict the level to which nitrogen is soluble in both the melt and the solid. Applications of this technique have revealed regions of "exclusion" in which the alloy, while within specification limits of prescribed, cannot be made by conventional melt processing. Furthermore, other investigations have found that substantial retrograde solubility of nitrogen exists, which can become problematic during subsequent melt processing and/or other finishing operations such as welding. Additionally, the CALPHAD method has been used to adjust primary melt conditions. To that end, nitrogen additions have been made using chrome nitride, silicon nitride, high-nitrogen ferrochrome as well as nitrogen gas. The advantages and disadvantages of each approach will be discussed and NETL experience in this area will be summarized with respect to steel structure.

Bacterial nitrogen fixation in sand bioreactors treating winery wastewater with a high carbon to nitrogen ratio.

Science.gov (United States)

Welz, Pamela J; Ramond, Jean-Baptiste; Braun, Lorenz; Vikram, Surendra; Le Roes-Hill, Marilize

2018-02-01

Heterotrophic bacteria proliferate in organic-rich environments and systems containing sufficient essential nutrients. Nitrogen, phosphorus and potassium are the nutrients required in the highest concentrations. The ratio of carbon to nitrogen is an important consideration for wastewater bioremediation because insufficient nitrogen may result in decreased treatment efficiency. It has been shown that during the treatment of effluent from the pulp and paper industry, bacterial nitrogen fixation can supplement the nitrogen requirements of suspended growth systems. This study was conducted using physicochemical analyses and culture-dependent and -independent techniques to ascertain whether nitrogen-fixing bacteria were selected in biological sand filters used to treat synthetic winery wastewater with a high carbon to nitrogen ratio (193:1). The systems performed well, with the influent COD of 1351 mg/L being reduced by 84-89%. It was shown that the nitrogen fixing bacterial population was influenced by the presence of synthetic winery effluent in the surface layers of the biological sand filters, but not in the deeper layers. It was hypothesised that this was due to the greater availability of atmospheric nitrogen at the surface. The numbers of culture-able nitrogen-fixing bacteria, including presumptive Azotobacter spp. exhibited 1-2 log increases at the surface. The results of this study confirm that nitrogen fixation is an important mechanism to be considered during treatment of high carbon to nitrogen wastewater. If biological treatment systems can be operated to stimulate this phenomenon, it may obviate the need for nitrogen addition. Copyright © 2017 Elsevier Ltd. All rights reserved.

The effect of nitrogen additions on bracken fern and its insect herbivores at sites with high and low atmospheric pollution

Science.gov (United States)

M.E. Jones; M.E. Fenn; T.D. Paine

2011-01-01

The impact of atmospheric pollution, including nitrogen deposition, on bracken fern herbivores has never been studied. Bracken fern is globally distributed and has a high potential to accumulate nitrogen in plant tissue. We examined the response of bracken fern and its herbivores to N fertilization at a high and low pollution site in forests downwind of Los Angeles,...

How to Calculate Your Institution's Nitrogen Footprint ...

Science.gov (United States)

The Nitrogen Footprint Tool (NFT) allows institutions to estimate and manage their nitrogen footprint, and EPA’s Sustainable and Healthy Communities program is supporting an effort to test and expand this approach at multiple colleges, universities and institutions across the US. The growing awareness of sustainability has prompted many institutions of higher education to assess and manage their environmental impact. Many universities have programs to decrease their carbon footprint, but carbon represents just one facet of an institution’s environmental impact. Nitrogen is also important because a university’s nitrogen loss to the environment contributes to smog, soil acidification, eutrophication, biodiversity loss, the enhanced greenhouse effect, stratospheric ozone depletion, and more. The attached data template and user’s manual was based on the first NFT created for a university (University of Virginia), and tested in 6 additional institutions (including University of New Hampshire, Brown University, Eastern Mennonite University, Colorado State University). The footprint includes nitrogen released to the environment due to: 1) food consumption; 2) food production, reported by specific food categories (vegetable products, seafood, dairy and eggs, meat); 3) research animals; 4) transportation, including fleet vehicles and commuter vehicles; 5) fertilizer application; and 6) utilities, separated into electricity and heating. The data template and

Nematodes, exotic earthworms and nitrogen addition: interactions between global change factors lead to cancellation effects.

Science.gov (United States)

De Long, Jonathan R

2017-07-01

Photos from the experiment described in Shao et al. (): (a) the endogeic (i.e. earthworms that typically live in the soil, burrowing horizontally to acquire nutrients) earthworm Pontoscolex corethrurus that was added to the plots; (b) P. corethrurus in a quiescence state in response to drought; (c) set-up of the control plots (i.e. no earthworms, ambient nitrogen) used in this experiment. [Colour figure can be viewed at wileyonlinelibrary.com] In Focus: Shao, Y., Zhang, W., Eisenhauer, N., Liu, T., Xiong, Y., Liang, C. & Fu, S. (2017) Nitrogen deposition cancels out exotic earthworm effects on plant-feeding nematode communities. Journal of Animal Ecology, 86, 708-717. In this issue of Journal of Animal Ecology, Shao et al. () explored how N addition and exotic earthworms interacted to impact on the plant-feeding nematode community. They demonstrate that exotic earthworm presence alone increased the abundance of less harmful plant-feeding nematodes and decreased the abundance of the more harmful plant-feeding nematodes. However, in plots receiving both exotic earthworms and N addition, such earthworm effects on the nematode community were negated. These findings pull focus on the need to simultaneously consider multiple global change factors (e.g. exotic species invasions and N deposition) when making predictions about how such factors might affect above- and below-ground interactions and thereby alter ecosystem function. © 2017 The Author. Journal of Animal Ecology © 2017 British Ecological Society.

Grassland Soil Carbon Responses to Nitrogen Additions

Science.gov (United States)

Hofmockel, K. S.; Tfailly, M.; Callister, S.; Bramer, L.; Thompson, A.

2017-12-01

Using a long-term continental scale experiment, we tested if increases in nitrogen (N) inputs augment the accumulation of plant and microbial residues onto mineral soil surfaces. This research investigates N effects on molecular biogeochemistry across six sites from the Nutrient Network (NutNet) experiment. The coupling between concurrently changing carbon (C) and N cycles remains a key uncertainty in understanding feedbacks between the terrestrial C cycle and climate change. Existing models do not consider the full suite of linked C-N processes, particularly belowground, that could drive future C-climate feedbacks. Soil harbors a wealth of diverse organic molecules, most of which have not been measured in hypothesis driven field research. For the first time we systematically assess the chemical composition of soil organic matter (SOM) and functional characteristics of the soil microbiome, to enhance our understanding of the molecular underpinnings of ecosystem C and N cycling. We have acquired soils from 5 ecosystem experiments across the US that have been subjected to 8 years of N addition treatments. These soils have been analyzed for chemical composition to identify how the soil fertility and stability is altered by N fertilization. We found distinct SOM signatures from our field experiments and shifts in soil chemistry in response to 8 years of N fertilization. Across all sites, we found the molecular composition of SOM varied with clay content, supporting the importance of soil mineralogy in the accumulation of specific chemical classes of SOM. While many molecules were common across sites, we discovered a suite of molecules that were site specific. N fertilization had a significant effect on SOM composition. Differences between control and N amended plots were greater in sites rich in lipids and more complex molecules, compared to sites with SOM rich in amino-sugar and protein like substances. Our results have important implications for how SOM is

The effect of nitrogen additions on oak foliage and herbivore communities at sites with high and low atmospheric pollution

International Nuclear Information System (INIS)

Eatough Jones, Michele; Paine, Timothy D.; Fenn, Mark E.

2008-01-01

To evaluate plant and herbivore responses to nitrogen we conducted a fertilization study at a low and high pollution site in the mixed conifer forests surrounding Los Angeles, California. Contrary to expectations, discriminant function analysis of oak herbivore communities showed significant response to N fertilization when atmospheric deposition was high, but not when atmospheric deposition was low. We hypothesize that longer-term fertilization treatments are needed at the low pollution site before foliar N nutrition increases sufficiently to affect herbivore communities. At the high pollution site, fertilization was also associated with increased catkin production and higher densities of a byturid beetle that feeds on the catkins of oak. Leaf nitrogen and nitrate were significantly higher at the high pollution site compared to the low pollution site. Foliar nitrate concentrations were positively correlated with abundance of sucking insects, leafrollers and plutellids in all three years of the study. - Nitrogen additions at sites impacted by air pollution were associated with altered foliar herbivore communities and increased densities of a catkin-feeding beetle on Quercus kellogii

Dosage and duration effects of nitrogen additions on ectomycorrhizal sporocarp production and functioning: an example from two N-limited boreal forests.

Science.gov (United States)

Hasselquist, Niles J; Högberg, Peter

2014-08-01

Although it is well known that nitrogen (N) additions strongly affect ectomycorrhizal (EM) fungal community composition, less is known about how different N application rates and duration of N additions affect the functional role EM fungi play in the forest N cycle.We measured EM sporocarp abundance and species richness as well as determined the δ (15)N in EM sporocarps and tree foliage in two Pinus sylvestris forests characterized by short- and long-term N addition histories and multiple N addition treatments. After 20 and 39 years of N additions, two of the long-term N addition treatments were terminated, thereby providing a unique opportunity to examine the temporal recovery of EM sporocarps after cessation of high N loading.In general, increasing N availability significantly reduced EM sporocarp production, species richness, and the amount of N retained in EM sporocarps. However, these general responses were strongly dependent on the application rate and duration of N additions. The annual addition of 20 kg·N·ha(-1) for the past 6 years resulted in a slight increase in the production and retention of N in EM sporocarps, whereas the addition of 100 kg·N·ha(-1)·yr(-1) during the same period nearly eliminated EM sporocarps. In contrast, long-term additions of N at rates of ca. 35 or 70 kg·N·ha(-1)·yr(-1) for the past 40 years did not eliminate tree carbon allocation to EM sporocarps, although there was a decrease in the abundance and a shift in the dominant EM sporocarp taxa. Despite no immediate recovery, EM sporocarp abundance and species richness approached those of the control 20 years after terminating N additions in the most heavily fertilized treatment, suggesting a recovery of carbon allocation to EM sporocarps after cessation of high N loading.Our results provide evidence for a tight coupling between tree carbon allocation to and N retention in EM sporocarps and moreover highlight the potential use of δ (15)N in EM sporocarps as a

Effects of N2O and O2 addition to nitrogen Townsend dielectric barrier discharges at atmospheric pressure on the absolute ground-state atomic nitrogen density

KAUST Repository

Es-sebbar, Et-touhami

2012-11-27

Absolute ground-state density of nitrogen atoms N (2p3 4S3/2) in non-equilibrium Townsend dielectric barrier discharges (TDBDs) at atmospheric pressure sustained in N2/N2O and N2/O2 gas mixtures has been measured using Two-photon absorption laser-induced fluorescence (TALIF) spectroscopy. The quantitative measurements have been obtained by TALIF calibration using krypton as a reference gas. We previously reported that the maximum of N (2p3 4S3/2) atom density is around 3 × 1014 cm-3 in pure nitrogen TDBD, and that this maximum depends strongly on the mean energy dissipated in the gas. In the two gas mixtures studied here, results show that the absolute N (2p3 4S3/2) density is strongly affected by the N2O and O2 addition. Indeed, the density still increases exponentially with the energy dissipated in the gas but an increase in N2O and O2 amounts (a few hundreds of ppm) leads to a decrease in nitrogen atom density. No discrepancy in the order of magnitude of N (2p3 4S3/2) density is observed when comparing results obtained in N2/N2O and N2/O2 mixtures. Compared with pure nitrogen, for an energy of ∼90 mJ cm-3, the maximum of N (2p3 4S3/2) density drops by a factor of 3 when 100 ppm of N2O and O2 are added and it reduces by a factor of 5 for 200 ppm, to reach values close to our TALIF detection sensitivity for 400 ppm (1 × 1013 cm -3 at atmospheric pressure). © 2013 IOP Publishing Ltd.

Short-term nitrogen additions can shift a coastal wetland from a sink to a source of N2O

Science.gov (United States)

Moseman-Valtierra, Serena; Gonzalez, Rosalinda; Kroeger, Kevin D.; Tang, Jianwu; Chao, Wei Chun; Crusius, John; Bratton, John F.; Green, Adrian; Shelton, James

2011-01-01

Coastal salt marshes sequester carbon at high rates relative to other ecosystems and emit relatively little methane particularly compared to freshwater wetlands. However, fluxes of all major greenhouse gases (N2O, CH4, and CO2) need to be quantified for accurate assessment of the climatic roles of these ecosystems. Anthropogenic nitrogen inputs (via run-off, atmospheric deposition, and wastewater) impact coastal marshes. To test the hypothesis that a pulse of nitrogen loading may increase greenhouse gas emissions from salt marsh sediments, we compared N2O, CH4 and respiratory CO2fluxes from nitrate-enriched plots in a Spartina patens marsh (receiving single additions of NaNO3 equivalent to 1.4 g N m−2) to those from control plots (receiving only artificial seawater solutions) in three short-term experiments (July 2009, April 2010, and June 2010). In July 2009, we also compared N2O and CH4 fluxes in both opaque and transparent chambers to test the influence of light on gas flux measurements. Background fluxes of N2O in July 2009 averaged −33 μmol N2O m−2 day−1. However, within 1 h of nutrient additions, N2O fluxes were significantly greater in plots receiving nitrate additions relative to controls in July 2009. Respiratory rates and CH4 fluxes were not significantly affected. N2O fluxes were significantly higher in dark than in transparent chambers, averaging 108 and 42 μmol N2O m−2 day−1 respectively. After 2 days, when nutrient concentrations returned to background levels, none of the greenhouse gas fluxes differed from controls. In April 2010, N2O and CH4 fluxes were not significantly affected by nitrate, possibly due to higher nitrogen demands by growing S. patens plants, but in June 2010 trends of higher N2O fluxes were again found among nitrate-enriched plots, indicating that responses to nutrient pulses may be strongest during the summer. In terms of carbon equivalents, the highest average N2O and CH4 fluxes observed, exceeded half

Influence of natural zeolite and nitrification inhibitor on organics degradation and nitrogen transformation during sludge composting.

Science.gov (United States)

Zhang, Junya; Sui, Qianwen; Li, Kun; Chen, Meixue; Tong, Juan; Qi, Lu; Wei, Yuansong

2016-01-01

Sludge composting is one of the most widely used treatments for sewage sludge resource utilization. Natural zeolite and nitrification inhibitor (NI) are widely used during composting and land application for nitrogen conservation, respectively. Three composting reactors (A--the control, B--natural zeolite addition, and C--3,4-dimethylpyrazole phosphate (DMPP) addition) were established to investigate the influence of NI and natural zeolite addition on organics degradation and nitrogen transformation during sludge composting conducted at the lab scale. The results showed that, in comparison with the control, natural zeolite addition accelerated organics degradation and the maturity of sludge compost was higher, while the DMPP addition slowed down the degradation of organic matters. Meanwhile, the nitrogen transformation functional genes including those responses for nitrification (amoA and nxrA) and denitrification (narG, nirS, nirK, and nosZ) were quantified through quantitative PCR (qPCR) to investigate the effects of natural zeolites and DMPP addition on nitrogen transformation. Although no significant difference in the abundance of nitrogen transformation functional genes was observed between treatments, addition of both natural zeolite and DMPP increases the final total nitrogen content by 48.6% and 23.1%, respectively. The ability of natural zeolite for nitrogen conservation was due to the absorption of NH3 by compost, and nitrogen conservation by DMPP was achieved by the source reduction of denitrification. Besides, it was assumed that the addition of natural zeolite and DMPP may affect the activity of these genes instead of the abundance.

[Effects of elevated atmospheric CO2 and nitrogen application on cotton biomass, nitrogen utilization and soil urease activity].

Science.gov (United States)

Lyu, Ning; Yin, Fei-hu; Chen, Yun; Gao, Zhi-jian; Liu, Yu; Shi, Lei

2015-11-01

In this study, a semi-open-top artificial climate chamber was used to study the effect of CO2 enrichment (360 and 540 µmol · mol(-1)) and nitrogen addition (0, 150, 300 and 450 kg · hm(-2)) on cotton dry matter accumulation and distribution, nitrogen absorption and soil urease activity. The results showed that the dry matter accumulation of bud, stem, leaf and the whole plant increased significantly in the higher CO2 concentration treatment irrespective of nitrogen level. The dry matter of all the detected parts of plant with 300 kg · hm(-2) nitrogen addition was significantly higher than those with the other nitrogen levels irrespective of CO2 concentration, indicating reasonable nitrogen fertilization could significantly improve cotton dry matter accumulation. Elevated CO2 concentration had significant impact on the nitrogen absorption contents of cotton bud and stem. Compared to those under CO2 concentration of 360 µmol · mol(-1), the nitrogen contents of bud and stem both increased significantly under CO2 concentration of 540 µmol · mol(-1). The nitrogen content of cotton bud in the treatment of 300 kg · hm(-2) nitrogen was the highest among the four nitrogen fertilizer treatments. While the nitrogen contents of cotton stem in the treatments of 150 kg · hm(-2) and 300 kg · hm(-2) nitrogen levels were higher than those in the treatment of 0 kg · hm(-2) and 450 kg · hm(-2) nitrogen levels. The nitrogen content of cotton leaf was significantly influenced by the in- teraction of CO2 elevation and N addition as the nitrogen content of leaf increased in the treatments of 0, 150 and 300 kg · hm(-2) nitrogen levels under the CO2 concentration of 540 µmol · mol(-1). The nitrogen content in cotton root was significantly increased with the increase of nitrogen fertilizer level under elevated CO2 (540 µmol · mol(-1)) treatment. Overall, the cotton nitrogen absorption content under the elevated CO2 (540 µmol · mol(-1)) treatment was higher than that

Effects of nitrogen loading on greenhouse gas emissions in salt marshes

Science.gov (United States)

Tang, J.; Moseman-Valtierra, S.; Kroeger, K. D.; Morkeski, K.; Mora, J.; Chen, X.; Carey, J.

2014-12-01

Salt marshes play an important role in global and regional carbon and nitrogen cycling. We tested the hypothesis that anthropogenic nitrogen loading alters greenhouse gas (GHG, including CO2, CH4, and N2O) emissions and carbon sequestration in salt marshes. We measured GHG emissions biweekly for two growing seasons across a nitrogen-loading gradient of four Spartina salt marshes in Waquoit Bay, Massachusetts. In addition, we conducted nitrogen addition experiments in a pristine marsh by adding low and high nitrate to triplicate plots bi-weekly during the summer. The GHG flux measurements were made in situ with a state-of-the-art mobile gas measurement system using the cavity ring down technology that consists of a CO2/CH4 analyzer (Picarro) and an N2O/CO analyzer (Los Gatos). We observed strong seasonal variations in greenhouse gas emissions. The differences in gas emissions across the nitrogen gradient were not significant, but strong pulse emissions of N2O were observed after nitrogen was artificially added to the marsh. Our results will facilitate model development to simulate GHG emissions in coastal wetlands and support methodology development to assess carbon credits in preserving and restoring coastal wetlands.

The impact of four decades of annual nitrogen addition on dissolved organic matter in a boreal forest soil

Science.gov (United States)

Rappe-George, M. O.; Gärdenäs, A. I.; Kleja, D. B.

2013-03-01

Addition of mineral nitrogen (N) can alter the concentration and quality of dissolved organic matter (DOM) in forest soils. The aim of this study was to assess the effect of long-term mineral N addition on soil solution concentration of dissolved organic carbon (DOC) and dissolved organic nitrogen (DON) in Stråsan experimental forest (Norway spruce) in central Sweden. N was added yearly at two levels of intensity and duration: the N1 treatment represented a lower intensity but a longer duration (43 yr) of N addition than the shorter N2 treatment (24 yr). N additions were terminated in the N2 treatment in 1991. The N treatments began in 1967 when the spruce stands were 9 yr old. Soil solution in the forest floor O, and soil mineral B, horizons were sampled during the growing seasons of 1995 and 2009. Tension and non-tension lysimeters were installed in the O horizon (n = 6), and tension lysimeters were installed in the underlying B horizon (n = 4): soil solution was sampled at two-week intervals. Although tree growth and O horizon carbon (C) and N stock increased in treatments N1 and N2, the concentration of DOC in O horizon leachates was similar in both N treatments and control. This suggests an inhibitory direct effect of N addition on O horizon DOC. Elevated DON and nitrate in O horizon leachates in the ongoing N1 treatment indicated a move towards N saturation. In B horizon leachates, the N1 treatment approximately doubled leachate concentrations of DOC and DON. DON returned to control levels, but DOC remained elevated in B horizon leachates in N2 plots nineteen years after termination of N addition. We propose three possible explanations for the increased DOC in mineral soil: (i) the result of decomposition of a larger amount of root litter, either directly producing DOC or (ii) indirectly via priming of old SOM, and/or (iii) a suppression of extracellular oxidative enzymes.

The impact of four decades of annual nitrogen addition on dissolved organic matter in a boreal forest soil

Directory of Open Access Journals (Sweden)

M. O. Rappe-George

2013-03-01

Full Text Available Addition of mineral nitrogen (N can alter the concentration and quality of dissolved organic matter (DOM in forest soils. The aim of this study was to assess the effect of long-term mineral N addition on soil solution concentration of dissolved organic carbon (DOC and dissolved organic nitrogen (DON in Stråsan experimental forest (Norway spruce in central Sweden. N was added yearly at two levels of intensity and duration: the N1 treatment represented a lower intensity but a longer duration (43 yr of N addition than the shorter N2 treatment (24 yr. N additions were terminated in the N2 treatment in 1991. The N treatments began in 1967 when the spruce stands were 9 yr old. Soil solution in the forest floor O, and soil mineral B, horizons were sampled during the growing seasons of 1995 and 2009. Tension and non-tension lysimeters were installed in the O horizon (n = 6, and tension lysimeters were installed in the underlying B horizon (n = 4: soil solution was sampled at two-week intervals. Although tree growth and O horizon carbon (C and N stock increased in treatments N1 and N2, the concentration of DOC in O horizon leachates was similar in both N treatments and control. This suggests an inhibitory direct effect of N addition on O horizon DOC. Elevated DON and nitrate in O horizon leachates in the ongoing N1 treatment indicated a move towards N saturation. In B horizon leachates, the N1 treatment approximately doubled leachate concentrations of DOC and DON. DON returned to control levels, but DOC remained elevated in B horizon leachates in N2 plots nineteen years after termination of N addition. We propose three possible explanations for the increased DOC in mineral soil: (i the result of decomposition of a larger amount of root litter, either directly producing DOC or (ii indirectly via priming of old SOM, and/or (iii a suppression of extracellular oxidative enzymes.

Elevated CO2 promotes long-term nitrogen accumulation only in combination with nitrogen addition.

Science.gov (United States)

Pastore, Melissa A; Megonigal, J Patrick; Langley, J Adam

2016-01-01

Biogeochemical models that incorporate nitrogen (N) limitation indicate that N availability will control the magnitude of ecosystem carbon uptake in response to rising CO2 . Some models, however, suggest that elevated CO2 may promote ecosystem N accumulation, a feedback that in the long term could circumvent N limitation of the CO2 response while mitigating N pollution. We tested this prediction using a nine-year CO2 xN experiment in a tidal marsh. Although the effects of CO2 are similar between uplands and wetlands in many respects, this experiment offers a greater likelihood of detecting CO2 effects on N retention on a decadal timescale because tidal marshes have a relatively open N cycle and can accrue soil organic matter rapidly. To determine how elevated CO2 affects N dynamics, we assessed the three primary fates of N in a tidal marsh: (1) retention in plants and soil, (2) denitrification to the atmosphere, and (3) tidal export. We assessed changes in N pools and tracked the fate of a (15) N tracer added to each plot in 2006 to quantify the fraction of added N retained in vegetation and soil, and to estimate lateral N movement. Elevated CO2 alone did not increase plant N mass, soil N mass, or (15) N label retention. Unexpectedly, CO2 and N interacted such that the combined N+CO2 treatment increased ecosystem N accumulation despite the stimulation in N losses indicated by reduced (15) N label retention. These findings suggest that in N-limited ecosystems, elevated CO2 is unlikely to increase long-term N accumulation and circumvent progressive N limitation without additional N inputs, which may relieve plant-microbe competition and allow for increased plant N uptake. © 2015 John Wiley & Sons Ltd.

Effects of belowground litter addition, increased precipitation and clipping on soil carbon and nitrogen mineralization in a temperate steppe

OpenAIRE

Ma, L.; Guo, C.; Xin, X.; Yuan, S.; Wang, R.

2013-01-01

Soil carbon (C) and nitrogen (N) cycling are sensitive to changes in environmental factors and play critical roles in the responses of terrestrial ecosystems to natural and anthropogenic perturbations. This study was conducted to quantify the effects of belowground particulate litter (BPL) addition, increased precipitation and their interactions on soil C and N mineralization in two adjacent sites where belowground photosynthate allocation was manipulated through vegetation ...

Responses of ecosystem carbon dioxide exchange to nitrogen addition in a freshwater marshland in Sanjiang Plain, Northeast China.

Science.gov (United States)

Zhang, Lihua; Song, Changchun; Nkrumah, Philip N

2013-09-01

It has widely been documented that nitrogen (N) stimulates plant growth and net primary production. But how N affects net ecosystem CO2 exchange (NEE) is still dispute. We conduct an experimental study to assess the response of NEE to N addition in a freshwater marsh. Experimental treatments involved elevated N and control treatments on triplicate 1 m(2) plots. Gas exchange, air temperature, plant biomass and leaf area as well as N% of leaf were measured from 2004 to 2005. The results indicated that N addition initially decreased the CO2 sequestration but the trend changed in the second year. It was concluded that N addition enhanced the greenhouse effect in marshland as far as global warming potential (GWP) is concerned. This increase was attributed to a substantial increase in CH4 and N2O emissions after N addition. We recommended long-term studies to further clarify the effect of N addition on NEE. Copyright © 2013 Elsevier Ltd. All rights reserved.

Attempts to improve nitrogen utilization efficiency of aquaponics through nitrifies addition and filler gradation.

Science.gov (United States)

Zou, Yina; Hu, Zhen; Zhang, Jian; Xie, Huijun; Liang, Shuang; Wang, Jinhe; Yan, Runxin

2016-04-01

Aquaponics has attracted worldwide attention in recent years and is considered as an alternative technology for conventional aquaculture. In this study, common carp (Cyprinus carpio) and pakchoi (Brassica chinensis) were cultured in lab-scale aquaponics, and attempts were conducted to enhance its nitrogen utilization efficiency (NUE) through two optimization methods, i.e., nitrifies addition (NA) and filler gradation (FG). Results showed that NA and FG could improve the NUE of aquaponics by 8.8 and 16.0%, respectively, compared with control. The total ammonia (TAN) and nitrite (NO2(-)) concentrations in NA and FG systems were maintained at relatively low level (TAN aquaponics also contributed to global warming. Although the two proposed attempts in this study caused more N2O emission, they made new breakthrough in improving the NUE of aquaponics.

Impact of warming, moderate nitrogen addition and bark herbivory on BVOC emissions and growth of Scots pine (Pinus sylvestris L.) seedlings.

Science.gov (United States)

Tiiva, Päivi; Häikiö, Elina; Kasurinen, Anne

2018-04-10

The changing climate will expose boreal forests to rising temperatures, increasing soil nitrogen (N) levels and an increasing risk of herbivory. The single and interaction effects of warming (+2 °C increase), moderate N addition (30 kg ha-1 year-1) and bark herbivory by large pine weevil (Hylobius abietis L.) on growth and emissions of biogenic volatile organic compounds (BVOCs) from shoots of Scots pine (Pinus sylvestris L.) seedlings were studied in growth chambers over 175 days. In addition, warming and N addition effects on shoot net photosynthesis (Pn) were measured. Nitrogen addition increased both shoot and root dry weights, whereas warming, in combination with herbivory, reduced stem height growth. Warming together with N addition increased current-year shoot Pn, whereas N effects on previous-year shoot Pn were variable over time. Warming decreased non-oxygenated monoterpene (MT) emissions in June and increased them in July. Of individual MT compounds, α-pinene, δ-3-carene, γ-terpinene and terpinolene were among the most frequently responsive compounds in warming treatments in the May-July period. Sesquiterpene emissions were observed only from warming treatments in July. Moderate N addition increased oxygenated monoterpenes in May, and MTs in June and September. However, N addition effect on MTs in June was clearer without warming than with warming. Bark herbivory tended to increase MT emissions in combination with warming and N addition 3 weeks after the damage caused by weevils. Of individual compounds in other BVOC blends, herbivory increased the emissions of methyl-benzene, benzene and hexanal in July. Hence, though both warming and N addition have a potential to change BVOC emissions from Scots pines, the N effect may also be partly cancelled by warming. Furthermore, herbivory pressure in combination with climate warming and N addition may, at least periodically, increase BVOC release to the atmosphere from young Scots pine seedlings.

Effects of elevated carbon dioxide and nitrogen addition on foliar stoichiometry of nitrogen and phosphorus of five tree species in subtropical model forest ecosystems

International Nuclear Information System (INIS)

Huang Wenjuan; Zhou Guoyi; Liu Juxiu; Zhang Deqiang; Xu Zhihong; Liu Shizhong

2012-01-01

The effects of elevated carbon dioxide (CO 2 ) and nitrogen (N) addition on foliar N and phosphorus (P) stoichiometry were investigated in five native tree species (four non-N 2 fixers and one N 2 fixer) in open-top chambers in southern China from 2005 to 2009. The high foliar N:P ratios induced by high foliar N and low foliar P indicate that plants may be more limited by P than by N. The changes in foliar N:P ratios were largely determined by P dynamics rather than N under both elevated CO 2 and N addition. Foliar N:P ratios in the non-N 2 fixers showed some negative responses to elevated CO 2 , while N addition reduced foliar N:P ratios in the N 2 fixer. The results suggest that N addition would facilitate the N 2 fixer rather than the non-N 2 fixers to regulate the stoichiometric balance under elevated CO 2 . - Highlights: ► Five native tree species in southern China were more limited by P than by N. ► Shifts in foliar N:P ratios were driven by P dynamic under the global change. ► N addition lowered foliar N:P ratios in the N 2 fixer under elevated CO 2 . - N addition could facilitate the N 2 fixer rather than the non-N 2 fixers to regulate foliar N and P stoichiometry under elevated CO 2 in subtropical forests.

Response of dissolved carbon and nitrogen concentrations to moderate nutrient additions in a tropical montane forest of south Ecuador

Science.gov (United States)

Velescu, Andre; Valarezo, Carlos; Wilcke, Wolfgang

2016-05-01

In the past two decades, the tropical montane rain forests in south Ecuador experienced increasing deposition of reactive nitrogen mainly originating from Amazonian forest fires, while Saharan dust inputs episodically increased deposition of base metals. Increasing air temperature and unevenly distributed rainfall have allowed for longer dry spells in a perhumid ecosystem. This might have favored mineralization of dissolved organic matter (DOM) by microorganisms and increased nutrient release from the organic layer. Environmental change is expected to impact the functioning of this ecosystem belonging to the biodiversity hotspots of the Earth. In 2007, we established a nutrient manipulation experiment (NUMEX) to understand the response of the ecosystem to moderately increased nutrient inputs. Since 2008, we have continuously applied 50 kg ha-1 a-1 of nitrogen (N), 10 kg ha-1 a-1 of phosphorus (P), 50 kg + 10 kg ha-1 a-1 of N and P and 10 kg ha-1 a-1 of calcium (Ca) in a randomized block design at 2000 m a.s.l. in a natural forest on the Amazonia-exposed slopes of the south Ecuadorian Andes. Nitrogen concentrations in throughfall increased following N+P additions, while separate N amendments only increased nitrate concentrations. Total organic carbon (TOC) and dissolved organic nitrogen (DON) concentrations showed high seasonal variations in litter leachate and decreased significantly in the P and N+P treatments, but not in the N treatment. Thus, P availability plays a key role in the mineralization of DOM. TOC/DON ratios were narrower in throughfall than in litter leachate but their temporal course did not respond to nutrient amendments. Our results revealed an initially fast, positive response of the C and N cycling to nutrient additions which declined with time. TOC and DON cycling only change if N and P supply are improved concurrently, while NO3-N leaching increases only if N is separately added. This indicates co-limitation of the microorganisms by N and P

Response of dissolved carbon and nitrogen concentrations to moderate nutrient additions in a tropical montane forest of south Ecuador

Directory of Open Access Journals (Sweden)

Andre eVelescu

2016-05-01

Full Text Available In the past two decades, the tropical montane rain forests in south Ecuador experienced increasing deposition of reactive nitrogen mainly originating from Amazonian forest fires, while Saharan dust inputs episodically increased deposition of base metals. Increasing air temperature and unevenly distributed rainfall have allowed for longer dry spells in a perhumid ecosystem. This might have favored mineralization of dissolved organic matter (DOM by microorganisms and increased nutrient release from the organic layer. Environmental change is expected to impact the functioning of this ecosystem belonging to the biodiversity hotspots of the Earth.In 2007, we established a nutrient manipulation experiment (NUMEX to understand the response of the ecosystem to moderately increased nutrient inputs. Since 2008, we have continuously applied 50 kg ha-1 a-1 of nitrogen (N, 10 kg ha-1 a-1 of phosphorus (P, 50 kg + 10 kg ha-1 a-1 of N and P and 10 kg ha-1 a-1 of calcium (Ca in a randomized block design at 2000 m a.s.l. in a natural forest on the Amazonia-exposed slopes of the south Ecuadorian Andes.Nitrogen concentrations in throughfall increased following N+P additions, while separate N amendments only increased nitrate concentrations. Total organic carbon (TOC and dissolved organic nitrogen (DON concentrations showed high seasonal variations in litter leachate and decreased significantly in the P and N+P treatments, but not in the N treatment. Thus, P availability plays a key role in the mineralization of DOM. TOC/DON ratios were narrower in throughfall than in litter leachate but their temporal course did not respond to nutrient amendments.Our results revealed an initially fast, positive response of the C and N cycling to nutrient additions which declined with time. TOC and DON cycling only change if N and P supply are improved concurrently, while NO3-N leaching increases only if N is separately added. This indicates co-limitation of the microorganisms by N

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

Science.gov (United States)

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

2013-01-01

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

Nitrogen addition, not initial phylogenetic diversity, increases litter decomposition by fungal communities.

Science.gov (United States)

Amend, Anthony S; Matulich, Kristin L; Martiny, Jennifer B H

2015-01-01

Fungi play a critical role in the degradation of organic matter. Because different combinations of fungi result in different rates of decomposition, determining how climate change will affect microbial composition and function is fundamental to predicting future environments. Fungal response to global change is patterned by genetic relatedness, resulting in communities with comparatively low phylogenetic diversity (PD). This may have important implications for the functional capacity of disturbed communities if lineages sensitive to disturbance also contain unique traits important for litter decomposition. Here we tested the relationship between PD and decomposition rates. Leaf litter fungi were isolated from the field and deployed in microcosms as mock communities along a gradient of initial PD, while species richness was held constant. Replicate communities were subject to nitrogen fertilization comparable to anthropogenic deposition levels. Carbon mineralization rates were measured over the course of 66 days. We found that nitrogen fertilization increased cumulative respiration by 24.8%, and that differences in respiration between fertilized and ambient communities diminished over the course of the experiment. Initial PD failed to predict respiration rates or their change in response to nitrogen fertilization, and there was no correlation between community similarity and respiration rates. Last, we detected no phylogenetic signal in the contributions of individual isolates to respiration rates. Our results suggest that the degree to which PD predicts ecosystem function will depend on environmental context.

Further improvement in ganoderic acid production in static liquid culture of Ganoderma lucidum by integrating nitrogen limitation and calcium ion addition.

Science.gov (United States)

Li, Huan-Jun; Zhang, De-Huai; Han, Li-Liang; Yu, Xuya; Zhao, Peng; Li, Tao; Zhong, Jian-Jiang; Xu, Jun-Wei

2016-01-01

To further improve the ganoderic acid (GA) production, a novel integrated strategy by combining nitrogen limitation and calcium ion addition was developed. The effects of the integrated combination on the content of GA-T (one powerful anticancer compound), their intermediates (squalene and lanosterol) and on the transcription levels of GA biosynthetic genes in G. lucidum fermentation were investigated. The maximum GA-T content with the integrated strategy were 1.87 mg/ 100 mg dry cell weight, which was 2.1-4.2 fold higher than that obtained with either calcium ion addition or nitrogen limitation alone, and it is also the highest record as ever reported in submerged fermentation of G. lucidum. The squalene content was increased by 3.9- and 2.2-fold in this case compared with either individual strategy alone. Moreover, the transcription levels of the GA biosynthetic genes encoding 3-hydroxy-3-methyglutaryl coenzyme A reductase and lanosterol synthase were also up-regulated by 3.3-7.5 and 1.3-2.3 fold, respectively.

Nitrogen fixation rates associated with the invasive macroalgae Sargassum horneri around Catalina Island, CA

Science.gov (United States)

DeLiberto, A.

2016-02-01

Nitrogen fixation is an important process which allows organisms access to biologically unavailable dinitrogen gas. Bacteria, known as diazotrophs use the enzyme nitrogenase to convert N2 to NH3. These bacteria, including certain species of heterotrophic bacteria and cyanobacteria, can be symbiotically associated with marine macroalgae, facilitating nutrient cycling in oligotrophic regions. As many species within the genera Sargassum are associated with nitrogen fixation, this study hypothesized that nitrogenase activity would be associated with the benthic invasive Sargassum horneri on Catalina Island. In the past decade, Sargassum horneri, an invasive from Japan, has spread throughout the waters around Catalina Island. Using the acetylene reduction procedure using flame ionization detection, initial nitrogenase activity of S. horneri sampled from Indian Rock was observed. Nitrogen fixation rates increased with decomposition, particularly in dark/anaerobic treatments, suggesting the presence of heterotrophic bacteria. In addition, acetate additions greatly increase nitrogen fixation rates, once again indicating heterotrophic nitrogen fixing bacteria.

Nitrogen limitation in the coastal heath at Anholt, Denmark

DEFF Research Database (Denmark)

Johnsen, Ib; Christensen, Steen; Riis-Nielsen, Torben

2014-01-01

) and phosphorus as KH2PO4 (P-addition) was carried out in the coastal grey dune vegetation of Anholt. The Naddition corresponded to 40 kg N ha−1 year−1 and the Paddition to 7 kg P ha−1 year−1 The experiment included N-, P-, N + P-addition and control. Lichens (genera: mainly Cladonia, Stereocaulon, Cetraria......The purpose of the study was to investigate, whether the coastal grey dune vegetation at Anholt, Denmark, is limited by nitrogen or phosphorus. The island Anholt (22,37 km2) is situated in the centre of Kattegat A two factor fertilization experiment with nitrogen as NH4NO3 (Naddition...... significantly following N and N + P addition. No effect was observed by P addition alone. N limitation of this coastal heath vegetation remote from agricultural and industrial activities was evident. The effect on the plant species of the single application was short-lived. After two-three years of enhanced...

Use of nitrogen stable isotope analysis to understand char nitrogen evolution during the fluidized-bed co-combustion of coal and sewage sludge

Energy Technology Data Exchange (ETDEWEB)

Ana Arenillas; Roberto Garcia; Chenggong Sun; Colin E. Snape; Angel H. Moreno; Fernando Rubiera; Jose J. Pis [University of Nottingham, Nottingham (United Kingdom). Nottingham Fuel and Energy Centre, School of Chemical, Environmental and Mining Engineering

2005-04-01

NOx emissions from sewage sludge combustion are a concern, because of the usually high nitrogen content of this fuel. The interactions during co-combustion in a fluidized-bed reactor of sewage sludge and a bituminous coal were evaluated, in relation to the nitrogen evolution during the combustion process. The nitrogen stable isotope measurements provide novel results regarding the tracing of nitrogen during combustion. Our preliminary results show that the co-combustion chars retain more nitrogen than expected, with the additional nitrogen being mainly derived from the sludge. Additional measurements are planned on the resultant co-combustion gases, to aid source apportionment of the NOx arising from coal/sewage interactions. 14 refs., 3 figs., 2 tabs.

Nitrogen Metabolite Repression of Metabolism and Virulence in the Human Fungal Pathogen Cryptococcus neoformans

Science.gov (United States)

Lee, I. Russel; Chow, Eve W. L.; Morrow, Carl A.; Djordjevic, Julianne T.; Fraser, James A.

2011-01-01

Proper regulation of metabolism is essential to maximizing fitness of organisms in their chosen environmental niche. Nitrogen metabolite repression is an example of a regulatory mechanism in fungi that enables preferential utilization of easily assimilated nitrogen sources, such as ammonium, to conserve resources. Here we provide genetic, transcriptional, and phenotypic evidence of nitrogen metabolite repression in the human pathogen Cryptococcus neoformans. In addition to loss of transcriptional activation of catabolic enzyme-encoding genes of the uric acid and proline assimilation pathways in the presence of ammonium, nitrogen metabolite repression also regulates the production of the virulence determinants capsule and melanin. Since GATA transcription factors are known to play a key role in nitrogen metabolite repression, bioinformatic analyses of the C. neoformans genome were undertaken and seven predicted GATA-type genes were identified. A screen of these deletion mutants revealed GAT1, encoding the only global transcription factor essential for utilization of a wide range of nitrogen sources, including uric acid, urea, and creatinine—three predominant nitrogen constituents found in the C. neoformans ecological niche. In addition to its evolutionarily conserved role in mediating nitrogen metabolite repression and controlling the expression of catabolic enzyme and permease-encoding genes, Gat1 also negatively regulates virulence traits, including infectious basidiospore production, melanin formation, and growth at high body temperature (39°–40°). Conversely, Gat1 positively regulates capsule production. A murine inhalation model of cryptococcosis revealed that the gat1Δ mutant is slightly more virulent than wild type, indicating that Gat1 plays a complex regulatory role during infection. PMID:21441208

Effect of exogenous carbon addition and the freeze-thaw cycle on soil microbes and mineral nitrogen pools1

Science.gov (United States)

Hu, Xia; Yin, Peng; Nong, Xiang; Liao, Jinhua

2018-01-01

To elucidate the alpine soil process in winter, the response mechanism of soil mineral nitrogen and soil microbes to exogenous carbon (0 mg C, 1 mg C, 2 mg C, 4 mg C and 8 mg C·g-1 dry soil) and the freeze-thaw cycle (-2 °C, -2 ∼ 2 °C, -20 ∼2°C) were studied by laboratory simulation. The freeze-thaw treatment had no significant effect on microbial biomass nitrogen and the number of bacteria. The soil mineral N pool, the number of fungi, and enzyme activities were obviously affected by the freeze-thaw cycle. A mild freeze-thaw cycle (-2∼2°C) significantly increased the number of fungi and catalase activity, while severe freeze-thaw cycle (-20∼2°C) obviously decreased invertase activity. The results suggested that both the freeze-thaw rate and freeze-thaw temperature amplitudes have a strong effect on soil microbial dynamics in the alpine zone in winter. The results showed that exogenous carbon addition significantly decreased soil NO3-N and NH4 +-N contents, increased soil microbial biomass, the number of microbes, and soil enzyme activities. The results showed that microbial growth in the eastern Tibetan Plateau was somewhat limited by available C. It may represent a larger potential pulse of soil nutrient for alpine plants in the next spring, and may be instrumental for plant community shifts under future climate change predictions due to the possible increased litter addition.

Nitrogen addition, not initial phylogenetic diversity, increases litter decomposition by fungal communities

Directory of Open Access Journals (Sweden)

Anthony Stuart Amend

2015-02-01

Full Text Available Fungi play a critical role in the degradation of organic matter. Because different combinations of fungi result in different rates of decomposition, determining how climate change will affect microbial composition and function is fundamental to predicting future environments. Fungal response to global change is patterned by genetic relatedness, resulting in communities with comparatively low phylogenetic diversity. This may have important implications for the functional capacity of disturbed communities if lineages sensitive to disturbance also contain unique traits important for litter decomposition. Here we tested the relationship between phylogenetic diversity and decomposition rates. Leaf litter fungi were isolated from the field and deployed in microcosms as mock communities along a gradient of initial phylogenetic diversity, while species richness was held constant. Replicate communities were subject to nitrogen fertilization comparable to anthropogenic deposition levels. Carbon mineralization rates were measured over the course of sixty-six days. We found that nitrogen fertilization increased cumulative respiration by 24.8%, and that differences in respiration between fertilized and ambient communities diminished over the course of the experiment. Initial phylogenetic diversity failed to predict respiration rates or their change in response to nitrogen fertilization, and there was no correlation between community similarity and respiration rates. Last, we detected no phylogenetic signal in the contributions of individual isolates to respiration rates. Our results suggest that the degree to which phylogenetic diversity predicts ecosystem function will depend on environmental context.

Effects of wood-ash addition on nitrogen turnover in a highly nitrogen loaded spruce site. Final project report

International Nuclear Information System (INIS)

Nohrstedt, H.Oe.; Hoegbom, Lars; Nordlund, Sten

2000-04-01

During two consecutive years, it was studied how a fertilization with 4.2 tonnes pelleted bark ash per ha, made six-seven years earlier, affected soil chemistry, nitrogen turnover and soil-water chemistry on a Norway spruce site in SW Sweden. The actual site has a very acidic soil. At the same time, the supply of inorganic N is rich. Measures against soil acidification, e. g. addition of ash or lime, may significantly influence the turnover of N with a subsequent risk for increased leaching. Thus, there is a potential conflict between two urgent environmental goals, i. e. to decrease acidification and to decrease the N load on aquatic ecosystems. In the humus layer and the upper 5 cm of the mineral soil, pH(H 2 O) had increased with at the most 0.2 units because of the ash addition. The easily extractable amounts of Mg, P and nitrate were slightly increased. The potential nitrification in the humus layer was generally higher in the ash treatment, but the difference. was not statistically significant. The soil water at 50 cm depth was 0.1-0.2 pH-units more acidic where ash had been applied. Simultaneously, there were tendencies for higher concentrations of nitrate, Al and K. This is the first time in Sweden that ash fertilization of a closed forest has given clear indications of an increased N leaching. As expected, the ash fertilization decreased the acidity of the top soil. On the contrary, the runoff became more acidic and more rich in Al. Thus, the ash fertilization has counteracted one of its primary goals, i. e. to produce a runoff less toxic to aquatic life. The acidification of the runoff may partially be because of acid production during nitrification

Effects of nitrogen addition on soil microbes and their implications for soil C emission in the Gurbantunggut Desert, center of the Eurasian Continent.

Science.gov (United States)

Huang, Gang; Cao, Yan Feng; Wang, Bin; Li, Yan

2015-05-15

Nitrogen (N) deposition can influence carbon cycling of terrestrial ecosystems. However, a general recognition of how soil microorganisms respond to increasing N deposition is not yet reached. We explored soil microbial responses to two levels of N addition (2.5 and 5 gN m(-2) yr(-1)) in interplant soil and beneath shrubs of Haloxylon ammodendron and their consequences to soil respiration in the Gurbantunggut Desert, northwestern China from 2011 to 2013. Microbial biomass and respiration were significantly higher beneath H. ammodendron than in interplant soil. The responses of microbial biomass carbon (MBC) and microbial respiration (MR) showed opposite responses to N addition in interplant and beneath H. ammodendron. N addition slightly increased MBC and MR in interplant soil and decreased them beneath H. ammodendron, with a significant inhibition only in 2012. N addition had no impacts on the total microbial physiological activity, but N addition decreased the labile carbon substrate utilization beneath H. ammodendron when N addition level was high. Phospholipid fatty acid (PLFA) analysis showed that N addition did not alter the soil microbial community structure as evidenced by the similar ratios of fungal to bacterial PLFAs and gram-negative to gram-positive bacterial PLFAs. Microbial biomass and respiration showed close correlations with soil water content and dissolved carbon, and they were independent of soil inorganic nitrogen across three years. Our study suggests that N addition effects on soil microorganisms and carbon emission are dependent on the respiratory substrates and water availability in the desert ecosystem. Copyright © 2015 Elsevier B.V. All rights reserved.

Interactive Effects of Nitrogen and Climate Change on Biodiversity

Science.gov (United States)

Porter, E. M.; Bowman, W. D.; Clark, C. M.; Compton, J. E.; Pardo, L. H.; Soong, J.

2011-12-01

Biodiversity has been described as the diversity of life on earth within species, between species and in ecosystems. Biodiversity contributes to regulating ecosystem services like climate, flood, disease, and water quality regulation. Biodiversity also supports and sustains ecosystem services that provide material goods like food, fiber, fuel, timber and water, and to non-material benefits like educational, recreational, spiritual, and aesthetic ecosystem services. The Millennium Ecosystem Assessment estimated that the rate of biodiversity loss due to human activity in the last 50 years has been more rapid than at any other time in human history, and that many of the drivers of biodiversity loss are increasing. The strongest drivers of biodiversity loss include habitat loss, overexploitation, invasive species, climate change, and pollution, including pollution from reactive nitrogen. Of these stressors, climate change and reactive nitrogen from anthropogenic activities are causing some of the most rapid changes. Climate change is causing warming trends that result in consistent patterns of poleward and elevational range shifts of flora and fauna, causing changes in biodiversity. Warming has also resulted in changes in phenology, particularly the earlier onset of spring events, migration, and lengthening of the growing season, disrupting predator-prey and plant-pollinator interactions. In addition to warming, elevated carbon dioxide by itself can affect biodiversity by influencing plant growth, soil water, tissue stoichiometry, and trophic interactions. Nitrogen enrichment also impacts ecosystems and biodiversity in a variety of ways. Nitrogen enhances plant growth, but has been shown to favor invasive, fast-growing species over native species adapted to low nitrogen conditions. Although there have been a limited number of empirical studies on climate change and nitrogen interactions, inferences can be drawn from observed responses to each stressor by itself. For

[Nitrogen input altered testate amoebae community in peatland of Sanjiang Plain, Northeast China].

Science.gov (United States)

Song, Li-hong; Yan, Xiu-min; Wang, Ke-hong; Zhu, Xiao-yan; Wu, Dong-hu

2015-02-01

In the present study, an in situ control experiment was carried out to explore the response of testate amoebae to exogenous nitrogen addition in peatland of Sanjiang Plain. The results showed that nitrogen addition increased the biomass of testate amoebae at lower levels (6 g N · m(-2)), while decreased it at higher levels (> 12 g N · m(-2)). At genus level, nitrogen addition significantly increased the biomass of Arcella and Phryganella, decreased the biomass of Euglypha. Only lower nitrogen addition significantly increased the biomass of Centropyxis. At species level, nitrogen addition significantly decreased the biomass of Euglypha rotunda, while the biomass of either Centropyxis cassis or Phryganella acropodia was increased by a lower nitrogen addition treatment. This study suggested that the response of peatland testate amoebae to nitrogen addition was species specific, which could potentially be used as an indicator for the environment of peatlands.

Effects of water and nitrogen addition on species turnover in temperate grasslands in northern China.

Directory of Open Access Journals (Sweden)

Zhuwen Xu

Full Text Available Global nitrogen (N deposition and climate change have been identified as two of the most important causes of current plant diversity loss. However, temporal patterns of species turnover underlying diversity changes in response to changing precipitation regimes and atmospheric N deposition have received inadequate attention. We carried out a manipulation experiment in a steppe and an old-field in North China from 2005 to 2009, to test the hypothesis that water addition enhances plant species richness through increase in the rate of species gain and decrease in the rate of species loss, while N addition has opposite effects on species changes. Our results showed that water addition increased the rate of species gain in both the steppe and the old field but decreased the rates of species loss and turnover in the old field. In contrast, N addition increased the rates of species loss and turnover in the steppe but decreased the rate of species gain in the old field. The rate of species change was greater in the old field than in the steppe. Water interacted with N to affect species richness and species turnover, indicating that the impacts of N on semi-arid grasslands were largely mediated by water availability. The temporal stability of communities was negatively correlated with rates of species loss and turnover, suggesting that water addition might enhance, but N addition would reduce the compositional stability of grasslands. Experimental results support our initial hypothesis and demonstrate that water and N availabilities differed in the effects on rate of species change in the temperate grasslands, and these effects also depend on grassland types and/or land-use history. Species gain and loss together contribute to the dynamic change of species richness in semi-arid grasslands under future climate change.

New approaches for description of nitrogen chemistry in combustion

Energy Technology Data Exchange (ETDEWEB)

Hupa, M.; Kilpinen, P.; Brink, A.; Norstroem, T. [Aabo Akademi, Turku (Finland)

1996-12-01

The aim of the project is to develop novel models for a more accurate description of nitrogen oxide emissions from combustion processes and to increase the understanding of the complex details of homogeneous nitrogen reactions in combustion and gasification. The topics dealt with during 1995 include: (1) effect of Cl on CO oxidation and nitrogen reactions, (2) effect of pressure on NO reduction by SNCR (in co-operation with the project 204), (3) NH{sub 3} conversion to N{sub 2} in gasification gases by selective oxidation (in cooperation with the project 203). In addition, a literature review of the models suggested for the interaction between turbulence and a chemical gas-phase reaction has been made. A commercial CFD code, FLUENT, has also been taken into use. (author)

Utilization of urea-nitrogen-15 in ruminants

International Nuclear Information System (INIS)

Boda, K.; Varady, J.; Havassy, I.

1976-01-01

In Merino sheep a series of experiments were carried out investigating exogenous and endogenous urea utilization. On the experimental sheep with isolated jejunum, rumen and intestine fistula, re-entral intestine cannulae, and after intra-ruminal or intra-intestinal 15 N-urea administration it was found that urea- 15 N takes part in the nitrogen recycling, and is utilized in the nitrogen pool. In experiments with synthetic protein-free diet, low protein diet and high nitrogen diet, after the intravenous administration of 15 N-urea the following findings were made: The results of experiments with synthetic diet, where the only nitrogen source was perorally (for 3-6 months) and then intravenously (for 3 months) administered urea, indicated the ability of ruminants to replace fully the nitrogen in the feed under certain conditions by increased endogenous urea recirculation. The results of the experiments with various nitrogen intakes showed that considerable amounts of urea- 15 N (44-96% from the given dose) were retained. Nitrogen compounds synthetized from blood urea- 15 N were recycled through the alimentary tract. Its secretion predominated in the forestomachs, abomasum and duodenum, and its reabsorption took place in the intestinal tract. From the 15 N incorporated into the nitrogenous substances which passed through the duodenum, 73-84% was reabsorbed. The retained 15 N was incorporated into the microbial and plasma proteins and its amide-N. On the basis of these results it is concluded that in addition to the rumeno-hepatal circulation, the entero-hepatal circulation of nitrogenous substances, including endogenous nitrogen, also plays an important role quantitatively and perhaps qualitatively in the process of re-utilizing the blood urea N for proteosynthesis and synthesis of other N-metabolites in ruminants. The hydrolysis of endogenous urea in the gastro-intestinal tract of ruminants and its utilization is a natural process indispensable for the maintenance of

Increasing fermentation efficiency at high sugar concentrations by supplementing an additional source of nitrogen during the exponential phase of the tequila fermentation process.

Science.gov (United States)

Arrizon, Javier; Gschaedler, Anne

2002-11-01

In the tequila industry, fermentation is traditionally achieved at sugar concentrations ranging from 50 to 100 g x L(-1). In this work, the behaviour of the Saccharomyces cerevisiae yeast (isolated from the juices of the Agave tequilana Weber blue variety) during the agave juice fermentation is compared at different sugar concentrations to determine if it is feasible for the industry to run fermentation at higher sugar concentrations. Fermentation efficiency is shown to be higher (above 90%) at a high concentration of initial sugar (170 g x L(-1)) when an additional source of nitrogen (a mixture of amino acids and ammonium sulphate, different than a grape must nitrogen composition) is added during the exponential growth phase.

Nitrogen behaviour during thermal drying of mechanically dewatered biosludge from pulp and paper industry.

Science.gov (United States)

Mustonen, Kati; Deviatkin, Ivan; Havukainen, Jouni; Horttanainen, Mika

2018-04-01

An ongoing call to implement a circular economy is underway in the European Union, and a specific attention has been placed on the forest industry, which seeks additional recycling routes for its side streams, including biosludge. Biosludge is often dried and incinerated, thus wasting the nitrogen contained therein. This paper describes a study in which the release of nitrogen during thermal drying, the impact of the drying temperatures of 130°C, 180°C, and 210°C on the mass of ammonia released, and the potential for recovery of nitrogen from biosludge were examined. The results indicate that 1310-1730 mg kgTS -1 of nitrogen was released, which corresponded to 56-74% of the soluble nitrogen in biosolids or 4.0-5.3% of the total nitrogen. Of this released nitrogen, 83-85% was identified in condensate and absorbing water, thus indicating a high potential for recovering nitrogen from biosludge.

Nitrogen trading tool

Science.gov (United States)

The nitrogen cycle is impacted by human activities, including those that increase the use of nitrogen in agricultural systems, and this impact can be seen in effects such as increased nitrate (NO3) levels in groundwater or surface water resources, increased concentration of nitrous oxide (N2O) in th...

Assimilation of 15N-labelled urea nitrogen and ammonium nitrate nitrogen by plants in case of root and non-root fertilization

International Nuclear Information System (INIS)

Muravin, Eh.A.; Kozhemyachko, V.A.; Vernichenko, I.V.

1974-01-01

Assimilation of 15 N labeled urea and ammonium nitrate in root and foliar application by spring wheat and barley has been studied during 1970-1973 period in a series of vegetative experiments at the Department of Agrochemistry, Timiryazev Agricultural Academy, and at D.N. Pryanishnikov Experimental Agrochemical Station. Additional fertilizer nitrogen applied at later ontogenesis stages (flowering and milky ripeness) is utilized mostly for protein synthesis in developing grains, thus leading to a significant increase in the relative grain protein content. A transfer of a part of nitrogen from the main ortion of fertilizer at later stages of nitrition results, at the same time, in a lower yield. Nitrogen utilization degree of urea and ammonium nitrate, when introduced before sowing or at the flowering stage is similar but in the latter case, however, additional assimilation of soil nitrogen is lower. The assimilation rate of nitrogen in root application is the lower the later the fertilizer is applied. When ammonium nitrate is additionally applied as nutrition to barley at the milky ripeness stage, ammonia and nitrate nitrogen are assimilated at the same rate and to the same extent but ammonia nitrogen is more rapidly used for protein synthesis and the rate of its transfer to the developing grains is higher. The rate of nitrogen assimilation at plant is much higher in foliar than in root application. Wheat utilizes more urea nitrogen at the flowering stage when root application is used but at the milky ripeness stage foliar application is more effective

Litter quality mediated nitrogen effect on plant litter decomposition regardless of soil fauna presence.

Science.gov (United States)

Zhang, Weidong; Chao, Lin; Yang, Qingpeng; Wang, Qingkui; Fang, Yunting; Wang, Silong

2016-10-01

Nitrogen addition has been shown to affect plant litter decomposition in terrestrial ecosystems. The way that nitrogen deposition impacts the relationship between plant litter decomposition and altered soil nitrogen availability is unclear, however. This study examined 18 co-occurring litter types in a subtropical forest in China in terms of their decomposition (1 yr of exposure in the field) with nitrogen addition treatment (0, 0.4, 1.6, and 4.0 mol·N·m -2 ·yr -1 ) and soil fauna exclusion (litter bags with 0.1 and 2 cm mesh size). Results showed that the plant litter decomposition rate is significantly reduced because of nitrogen addition; the strength of the nitrogen addition effect is closely related to the nitrogen addition levels. Plant litters with diverse quality responded to nitrogen addition differently. When soil fauna was present, the nitrogen addition effect on medium-quality or high-quality plant litter decomposition rate was -26% ± 5% and -29% ± 4%, respectively; these values are significantly higher than that of low-quality plant litter decomposition. The pattern is similar when soil fauna is absent. In general, the plant litter decomposition rate is decreased by soil fauna exclusion; an average inhibition of -17% ± 1.5% was exhibited across nitrogen addition treatment and litter quality groups. However, this effect is weakly related to nitrogen addition treatment and plant litter quality. We conclude that the variations in plant litter quality, nitrogen deposition, and soil fauna are important factors of decomposition and nutrient cycling in a subtropical forest ecosystem. © 2016 by the Ecological Society of America.

Short-term Effect of Nitrogen Addition on Microbial and Root Respiration in an Alpine Spruce Ecosystem

Directory of Open Access Journals (Sweden)

Jian Wang1

2017-03-01

Full Text Available Soil respiration plays an important role in the carbon (C flux of the global C cycle and is greatly affected by nitrogen (N additions in the form of deposition or fertilization. The aim of this study was to investigate the response of total soil respiration (Rs, microbial respiration (Rm, and root respiration (Rr to short-term N addition and the potential mechanisms of short-term N deposition influencing soil respiration in an alpine spruce ecosystem. Four N treatment levels (0, 50, 100, 150 kg N ha-1 year-1 were applied monthly in a Picea balfouriana (commonly known as "alpine spruce" plantation beginning in November 2013 and Rs, Rm, and Rr were measured from May to November 2014. The results show that simulated N depositions stimulate Rs, Rm, and Rr and the beneficial effects decreased along N gradients from hourly to seasonal scales. The seasonal temperature coefficients (Q10 of Rs, Rm, and Rr ranged from 2.50 to 3.8, 2.99 to 4.63, and 1.86 to 2.96, while the diurnal Q10 ranged from 1.71 to 2.04, 1.89 to 2.32, 1.42 to 1.75, and there was a similar trend with soil respiration along N gradients. In addition, Rr showed significant positive correlation with fine root biomass, and Rm was likely driven by soil enzyme related to the microbial C cycle in the growing season. Our results indicate that short-term N addition stimulated fine root biomass and soil enzymatic activity to bring about a potential increase in soil respiration rates under low-N addition, while the opposite occurred under high-N addition.

Global change and biological soil crusts: Effects of ultraviolet augmentation under altered precipitation regimes and nitrogen additions

Science.gov (United States)

Belnap, J.; Phillips, S.L.; Flint, S.; Money, J.; Caldwell, M.

2008-01-01

Biological soil crusts (BSCs), a consortium of cyanobacteria, lichens, and mosses, are essential in most dryland ecosystems. As these organisms are relatively immobile and occur on the soil surface, they are exposed to high levels of ultraviolet (UV) radiation and atmospheric nitrogen (N) deposition, rising temperatures, and alterations in precipitation patterns. In this study, we applied treatments to three types of BSCs (early, medium, and late successional) over three time periods (spring, summer, and spring-fall). In the first year, we augmented UV and altered precipitation patterns, and in the second year, we augmented UV and N. In the first year, with average air temperatures, we saw little response to our treatments except quantum yield, which was reduced in dark BSCs during one of three sample times and in Collema BSCs two of three sample times. There was more response to UV augmentation the second year when air temperatures were above average. Declines were seen in 21% of the measured variables, including quantum yield, chlorophyll a, UV-protective pigments, nitrogenase activity, and extracellular polysaccharides. N additions had some negative effects on light and dark BSCs, including the reduction of quantum yield, ??-carotene, nitrogenase activity, scytonemin, and xanthophylls. N addition had no effects on the Collema BSCs. When N was added to samples that had received augmented UV, there were only limited effects relative to samples that received UV without N. These results indicate that the negative effect of UV and altered precipitation on BSCs will be heightened as global temperatures increase, and that as their ability to produce UV-protective pigments is compromised, physiological functioning will be impaired. N deposition will only ameliorate UV impacts in a limited number of cases. Overall, increases in UV will likely lead to lowered productivity and increased mortality in BSCs through time, which, in turn, will reduce their ability to contribute

RELAP5-3D Code Includes ATHENA Features and Models

International Nuclear Information System (INIS)

Riemke, Richard A.; Davis, Cliff B.; Schultz, Richard R.

2006-01-01

Version 2.3 of the RELAP5-3D computer program includes all features and models previously available only in the ATHENA version of the code. These include the addition of new working fluids (i.e., ammonia, blood, carbon dioxide, glycerol, helium, hydrogen, lead-bismuth, lithium, lithium-lead, nitrogen, potassium, sodium, and sodium-potassium) and a magnetohydrodynamic model that expands the capability of the code to model many more thermal-hydraulic systems. In addition to the new working fluids along with the standard working fluid water, one or more noncondensable gases (e.g., air, argon, carbon dioxide, carbon monoxide, helium, hydrogen, krypton, nitrogen, oxygen, SF 6 , xenon) can be specified as part of the vapor/gas phase of the working fluid. These noncondensable gases were in previous versions of RELAP5-3D. Recently four molten salts have been added as working fluids to RELAP5-3D Version 2.4, which has had limited release. These molten salts will be in RELAP5-3D Version 2.5, which will have a general release like RELAP5-3D Version 2.3. Applications that use these new features and models are discussed in this paper. (authors)

Nitrogen-doped carbon monolith for alkaline supercapacitors and understanding nitrogen-induced redox transitions.

Science.gov (United States)

Wang, Da-Wei; Li, Feng; Yin, Li-Chang; Lu, Xu; Chen, Zhi-Gang; Gentle, Ian R; Lu, Gao Qing; Cheng, Hui-Ming

2012-04-23

A nitrogen-doped porous carbon monolith was synthesized as a pseudo-capacitive electrode for use in alkaline supercapacitors. Ammonia-assisted carbonization was used to dope the surface with nitrogen heteroatoms in a way that replaced carbon atoms but kept the oxygen content constant. Ammonia treatment expanded the micropore size-distributions and increased the specific surface area from 383 m(2) g(-1) to 679 m(2) g(-1). The nitrogen-containing porous carbon material showed a higher capacitance (246 F g(-1)) in comparison with the nitrogen-free one (186 F g(-1)). Ex situ electrochemical spectroscopy was used to investigate the evolution of the nitrogen-containing functional groups on the surface of the N-doped carbon electrodes in a three-electrode cell. In addition, first-principles calculations were explored regarding the electronic structures of different nitrogen groups to determine their relative redox potentials. We proposed possible redox reaction pathways based on the calculated redox affinity of different groups and surface analysis, which involved the reversible attachment/detachment of hydroxy groups between pyridone and pyridine. The oxidation of nitrogen atoms in pyridine was also suggested as a possible reaction pathway. Copyright © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Integrated Science Assessment (ISA) for Oxides of Nitrogen ...

Science.gov (United States)

This draft ISA document represents a concise synthesis and evaluation of the most policy-relevant science and will ultimately provide the scientific bases for EPA’s decision on retaining or revising the current secondary standards for NO2, SO2, PM 2.5 and PM 10 since the prior release of the assessment. The intent of the ISA, according to the CAA, is to “accurately reflect the latest scientific knowledge expected from the presence of [a] pollutant in ambient air” (U.S. Code, 1970a, 1970b). It includes scientific research from atmospheric sciences, exposure and deposition, biogeochemistry, hydrology, soil science, marine science, plant physiology, animal physiology, and ecology conducted at multiple scales (e.g., population, community, ecosystem, landscape levels). Key information and judgments formerly found in the Air Quality Criteria Documents (AQCDs) for oxides of nitrogen, oxides of nitrogen and particulate matter for ecological effects are included; Appendixes provide additional details supporting the ISA. Together, the ISA and Appendixes serve to update and revise the last oxides of nitrogen and oxides of sulfur ISA which was published in 2008 and the ecological portion of the last particulate matter ISA, which was published in 2009.

Microbial properties explain temporal variation in soil respiration in a grassland subjected to nitrogen addition

Science.gov (United States)

Li, Yue; Liu, Yinghui; Wu, Shanmei; Niu, Lei; Tian, Yuqiang

2015-01-01

The role of soil microbial variables in shaping the temporal variability of soil respiration has been well acknowledged but is poorly understood, particularly under elevated nitrogen (N) deposition conditions. We measured soil respiration along with soil microbial properties during the early, middle, and late growing seasons in temperate grassland plots that had been treated with N additions of 0, 2, 4, 8, 16, or 32 g N m−2 yr−1 for 10 years. Representing the averages over three observation periods, total (Rs) and heterotrophic (Rh) respiration were highest with 4 g N m−2 yr−1, but autotrophic respiration (Ra) was highest with 8 to 16 g N m−2 yr−1. Also, the responses of Rh and Ra were unsynchronized considering the periods separately. N addition had no significant impact on the temperature sensitivity (Q10) for Rs but inhibited the Q10 for Rh. Significant interactions between observation period and N level occurred in soil respiration components, and the temporal variations in soil respiration components were mostly associated with changes in microbial biomass carbon (MBC) and phospholipid fatty acids (PLFAs). Further observation on soil organic carbon and root biomass is needed to reveal the long-term effect of N deposition on soil C sequestration. PMID:26678303

Assimilation of /sup 15/N-labelled urea nitrogen and ammonium nitrate nitrogen by plants in case of root and non-root fertilization

Energy Technology Data Exchange (ETDEWEB)

Muravin, E A; Kozhemyachko, V A; Vernichenko, I V

1974-01-01

Assimilation of /sup 15/N labeled urea and ammonium nitrate in root and foliar application by spring wheat and barley has been studied during 1970-1973 period in a series of vegetative experiments at the Department of Agrochemistry, Timiryazev Agricultural Academy, and at D.N. Pryanishnikov Experimental Agrochemical Station. Additional fertilizer nitrogen applied at later ontogenesis stages (flowering and milky ripeness) is utilized mostly for protein synthesis in developing grains, thus leading to a significant increase in the relative grain protein content. A transfer of a part of nitrogen from the main portion of fertilizer at later stages of nitrition results, at the same time, in a lower yield. Nitrogen utilization degree of urea and ammonium nitrate, when introduced before sowing or at the flowering stage is similar but in the latter case, however, additional assimilation of soil nitrogen is lower. The assimilation rate of nitrogen in root application is the lower the later the fertilizer is applied. When ammonium nitrate is additionally applied as nutrition to barley at the milky ripeness stage, ammonia and nitrate nitrogen are assimilated at the same rate and to the same extent but ammonia nitrogen is more rapidly used for protein synthesis and the rate of its transfer to the developing grains is higher. The rate of nitrogen assimilation at plant is much higher in foliar than in root application. Wheat utilizes more urea nitrogen at the flowering stage when root application is used but at the milky ripeness stage foliar application is more effective.

The nitrogen cascade from agricultural soils to the sea: modelling nitrogen transfers at regional watershed and global scales

OpenAIRE

Billen, Gilles; Garnier, Josette; Lassaletta, Luis

2013-01-01

The nitrogen cycle of pre-industrial ecosystems has long been remarkably closed, in spite of the high mobility of this element in the atmosphere and hydrosphere. Inter-regional and international commercial exchanges of agricultural goods, which considerably increased after the generalization of the use of synthetic nitrogen fertilizers, introduced an additional type of nitrogen mobility, which nowadays rivals the atmospheric and hydrological fluxes in intensity, and causes their enhancement a...

Forest fuel reduces the nitrogen load

International Nuclear Information System (INIS)

Lundborg, A.

1993-03-01

A study of the literature was made on the basis of the following hypothesis: ''If nitrogen-rich felling residues are removed from the forest, the nitrogen load on the forest ecosystem is decreased and the risk of nitrogen saturation also decreases''. The study was designed to provide information on how the nitrogen situation is influenced if felling residues are removed from nitrogen-loaded forests and used as fuel. Felling residues release very little nitrogen during the first years after felling. They can immobilize nitrogen from the surroundings, make up a considerable addition to the nitrogen store in the soil, but also release nitrogen in later stages of degradation. The slash has an influence on the soil climate and thus on soil processes. Often there is an increase in the mineralization of litter and humus below the felling residues. At the same time, nitrification is favoured, particularly if the slash is left in heaps. Felling residues contain easily soluble nutrients that stimulate the metabolization of organic matter that otherwise is rather resistant to degradation. The slash also inhibits the clear-cut vegetation and its uptake of nitrogen. These effects result in increased leaching of nitrogen and minerals if the felling residues are left on the site. (99 refs.)

Effects of experimental warming and nitrogen addition on soil respiration and CH4 fluxes from crop rotations of winter wheat–soybean/fallow

DEFF Research Database (Denmark)

Liu, L; Hu, C; Yang, P

2015-01-01

Soil respiration and CH4 emissions play a significant role in the global carbon balance. However, in situ studies in agricultural soils on responses of soil respiration and CH4 fluxes to climate warming are still sparse, especially from long-term studies with year-round heating. A warming...... by affecting soil NH4 concentration. Across years, CH4 emissions were negatively correlated with soil temperature in N1 treatment. Soil respiration showed clear seasonal fluctuations, with the largest emissions during summer and smallest in winter. Warming and nitrogen fertilization had no significant effects...... on total cumulative soil CO2 fluxes. Soil respiration was positively correlated with microbial biomass C, and microbial biomass C was not affected significantly by warming or nitrogen addition. The lack of significant effects of warming on soil respiration may have resulted from: (1) warming-induced soil...

Regulation of Carbon Flow by Nitrogen and Light in the Red Alga, Gelidium coulteri.

Science.gov (United States)

Macler, B A

1986-09-01

The red alga Gelidium coulteri Harv. photosynthetically fixed [(14)C] bicarbonate at high rates under defined conditions in unialgal laboratory culture. The fixation rate and flow of photosynthate into various end products were dependent on the nitrogen status of the tissue. Plants fed luxury levels of nitrogen (approximately 340 micromolar) showed fixation rates several-fold higher than those seen for plants starved for nitrogen. The addition of NO(3) (-) or NH(4) (+) to such starved plants further inhibited fixation over at least the first several hours after addition. The majority of (14)C after incubations of 30 minutes to 8 hours was found in the compounds floridoside, agar and floridean starch. In addition, amino acids and intermediate compounds of the reductive pentose phosphate pathway, glycolytic pathway and tricarboxylic acid cycle were detected. Nitrogen affected the partitioning of labeled carbon into these compounds. Plants under luxury nitrogen conditions had higher floridoside levels and markedly lower amounts of agar and starch than found in plants limited for nitrogen. Amino acid, phycobiliprotein and chlorophyll levels were also significantly higher in nitrogen-enriched plants. Addition of NO(3) (-) to starved plants led to an increase in floridoside, tricarboxylic acid cycle intermediates and amino acids within 1 hour and inhibited carbon flow into agar and starch. Carbon fixation in the dark was only 1 to 7% of that seen in the light. Dark fixation of [(14)C]bicarbonate yielded label primarily in tricarboxylic acid cycle intermediates, amino acids and polysaccharides. Nitrogen stimulated amino acid synthesis at the expense of agar and starch. Floridoside was only a minor component in the dark. Pulse-chase experiments, designed to show carbon turnover, indicated a 2-fold increase in labeling of agar over 96 hours of chase in the light. No increases were seen in the dark. Low molecular weight pools, including floridoside, decreased 2- to 5-fold

A nitrogen mass balance for California

Science.gov (United States)

Liptzin, D.; Dahlgren, R. A.

2010-12-01

Human activities have greatly altered the global nitrogen cycle and these changes are apparent in water quality, air quality, ecosystem and human health. However, the relative magnitude of the sources of new reactive nitrogen and the fate of this nitrogen is not well established. Further, the biogeochemical aspects of the nitrogen cycle are often studied in isolation from the economic and social implications of all the transformations of nitrogen. The California Nitrogen Assessment is an interdisciplinary project whose aim is evaluating the current state of nitrogen science, practice, and policy in the state of California. Because of the close proximity of large population centers, highly productive and diverse agricultural lands and significant acreage of undeveloped land, California is a particularly interesting place for this analysis. One component of this assessment is developing a mass balance of nitrogen as well as identifying gaps in knowledge and quantifying uncertainty. The main inputs of new reactive nitrogen to the state are 1) synthetic nitrogen fertilizer, 2) biological nitrogen fixation, and 3) atmospheric nitrogen deposition. Permanent losses of nitrogen include 1) gaseous losses (N2, N2O, NHx, NOy), 2) riverine discharge, 3) wastewater discharge to the ocean, and 4) net groundwater recharge. A final term is the balance of food, feed, and fiber to support the human and animal populations. The largest input of new reactive nitrogen to California is nitrogen fertilizer, but both nitrogen fixation and atmospheric deposition contribute significantly. Non-fertilizer uses, such as the production of nylon and polyurethane, constitutes about 5% of the synthetic N synthesized production. The total nitrogen fixation in California is roughly equivalent on the 400,000 ha of alfalfa and the approximately 40 million ha of natural lands. In addition, even with highly productive agricultural lands, the large population of livestock, in particular dairy cows

Exogenous Nitrogen Addition Reduced the Temperature Sensitivity of Microbial Respiration without Altering the Microbial Community Composition

Directory of Open Access Journals (Sweden)

Hui Wei

2017-12-01

Full Text Available Atmospheric nitrogen (N deposition is changing in both load quantity and chemical composition. The load effects have been studied extensively, whereas the composition effects remain poorly understood. We conducted a microcosm experiment to study how N chemistry affected the soil microbial community composition characterized by phospholipid fatty acids (PLFAs and activity indicated by microbial CO2 release. Surface and subsurface soils collected from an old-growth subtropical forest were supplemented with three N-containing materials (ammonium, nitrate, and urea at the current regional deposition load (50 kg ha-1 yr-1 and incubated at three temperatures (10, 20, and 30°C to detect the interactive effects of N deposition and temperature. The results showed that the additions of N, regardless of form, did not alter the microbial PLFAs at any of the three temperatures. However, the addition of urea significantly stimulated soil CO2 release in the early incubation stage. Compared with the control, N addition consistently reduced the temperature dependency of microbial respiration, implying that N deposition could potentially weaken the positive feedback of the warming-stimulated soil CO2 release to the atmosphere. The consistent N effects for the surface and subsurface soils suggest that the effects of N on soil microbial communities may be independent of soil chemical contents and stoichiometry.

The nitrogen cycle: Atmosphere interactions

Science.gov (United States)

Levine, J. S.

1984-01-01

Atmospheric interactions involving the nitrogen species are varied and complex. These interactions include photochemical reactions, initiated by the absorption of solar photons and chemical kinetic reactions, which involve both homogeneous (gas-to-gas reactions) and heterogeneous (gas-to-particle) reactions. Another important atmospheric interaction is the production of nitrogen oxides by atmospheric lightning. The nitrogen cycle strongly couples the biosphere and atmosphere. Many nitrogen species are produced by biogenic processes. Once in the atmosphere nitrogen oxides are photochemically and chemically transformed to nitrates, which are returned to the biosphere via precipitation, dry deposition and aerosols to close the biosphere-atmosphere nitrogen cycle. The sources, sinks and photochemistry/chemistry of the nitrogen species; atmospheric nitrogen species; souces and sinks of nitrous oxide; sources; sinks and photochemistry/chemistry of ammonia; seasonal variation of the vertical distribution of ammonia in the troposphere; surface and atmospheric sources of the nitrogen species, and seasonal variation of ground level ammonia are summarized.

Members of the LBD Family of Transcription Factors Repress Anthocyanin Synthesis and Affect Additional Nitrogen Responses in Arabidopsis

OpenAIRE

Rubin, G.; Tohge, T.; Matsuda, F.; Saito, K.; Scheible, W.

2009-01-01

Nitrogen (N) and nitrate (NO3-) per se regulate many aspects of plant metabolism, growth, and development. N/NO3- also suppresses parts of secondary metabolism, including anthocyanin synthesis. Molecular components for this repression are unknown. We report that three N/NO3--induced members of the LATERAL ORGAN BOUNDARY DOMAIN (LBD) gene family of transcription factors (LBD37, LBD38, and LBD39) act as negative regulators of anthocyanin biosynthesis in Arabidopsis thaliana. Overexpression of e...

Effect of nitrogen on creep properties of type 316L(N) stainless steels

International Nuclear Information System (INIS)

Kim, Dae Whan; Lee, Yoon Kyu; Kim, Woo Gon; Ryu, Woo Seog

2001-01-01

The effects of nitrogen on the creep properties of type 316(N) stainless steels with three different nitrogen contents from 0.04% to 0.15% were investigated. Creep tests were carried out using constant-load single-lever machines at 550∼650 .deg. C in the air. The time to rupture increased and the minimum creep rate decreased with the addition of nitrogen. At constant stress, the rupture elongation decreased with the addition of nitrogen. Intergranular and transgranular fracture mode were mixed in all specimens. Cavity and carbides were nucleated at grain boundary and the number of cavity and carbide at constant stress was increased with the addition of nitrogen because of the increase in the time to rupture and carbide precipitation due to the addition of nitrogen. The increase of rupture time with the addition of nitrogen for type 316L(N) stainless steel was attributed to the combined effect of the decrease of minimum creep rate due to the increase of tensile strength and the rupture elongation due to the precipitation at grain boundaries

Effects of elevated nitrogen deposition on soil microbial biomass carbon in major subtropical forests of southern China

Institute of Scientific and Technical Information of China (English)

Hui WANG; Jiangming MO; Xiankai LU; Jinghua XUE; Jiong LI; Yunting FANG

2009-01-01

The effects of elevated nitrogen deposition on soil microbial biomass carbon (C) and extractable dissolved organic carbon (DOC) in three types of forest of southern China were studied in November, 2004 and June, 2006. Plots were established in a pine forest (PF), a mixed pine and broad-leaved forest (MF) and monsoon evergreen broad-leaved forest (MEBF) in the Dinghushan Nature Reserve. Nitrogen treatments included a control (no N addition), low N (50 kg N/(hm2.a)), medium N (100 kg N/ (hm2. a)) and high N (150 kg N/(hm2. a)). Microbial biomass C and extractable DOC were determined using a chloro-form fumigation-extraction method. Results indicate that microbial biomass C and extractable DOC were higher in June, 2006 than in November, 2004 and higher in the MEBF than in the PF or the MF. The response of soil microbial biomass C and extractable DOC to nitrogen deposition varied depending on the forest type and the level of nitrogen treatment. In the PF or MF forests, no significantly different effects of nitrogen addition were found on soil microbial biomass C and extractable DOC. In the MEBF, however, the soil microbial biomass C generally decreased with increased nitrogen levels and high nitrogen addition significantly reduced soil microbial biomass C. The response of soil extractable DOC to added nitrogen in the MEBF shows the opposite trend to soil microbial biomass C. These results suggest that nitrogen deposition may increase the accumulation of soil organic carbon in the MEBF in the study region.

Nitrogen on Mars: Insights from Curiosity

Science.gov (United States)

Stern, J. C.; Sutter, B.; Jackson, W. A.; Navarro-Gonzalez, Rafael; McKay, Chrisopher P.; Ming, W.; Archer, P. Douglas; Glavin, D. P.; Fairen, A. G.; Mahaffy, Paul R.

2017-01-01

Recent detection of nitrate on Mars indicates that nitrogen fixation processes occurred in early martian history. Data collected by the Sample Analysis at Mars (SAM) instrument on the Curiosity Rover can be integrated with Mars analog work in order to better understand the fixation and mobility of nitrogen on Mars, and thus its availability to putative biology. In particular, the relationship between nitrate and other soluble salts may help reveal the timing of nitrogen fixation and post-depositional behavior of nitrate on Mars. In addition, in situ measurements of nitrogen abundance and isotopic composition may be used to model atmospheric conditions on early Mars.

Oxygen and nitrogen plasma etching of three-dimensional hydroxyapatite/chitosan scaffolds fabricated by additive manufacturing

Science.gov (United States)

Myung, Sung-Woon; Kim, Byung-Hoon

2016-01-01

Three-dimensional (3D) chitosan and hydroxyapatite (HAp)/chitosan (CH) scaffolds were fabricated by additive manufacturing, then their surfaces were etched with oxygen (O2) and nitrogen (N2) plasma. O2 and N2 plasma etching was performed to increase surface properties such as hydrophilicity, roughness, and surface chemistry on the scaffolds. After etching, hydroxyapatite was exposed on the surface of 3D HAp/CH scaffolds. The surface morphology and chemical properties were characterized by contact angle measurement, scanning electron microscopy, X-ray diffraction, and attenuated total reflection Fourier infrared spectroscopy. The cell viability of 3D chitosan scaffolds was examined by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay. The differentiation of preosteoblast cells was evaluated by alkaline phosphatase assay. The cell viability was improved by O2 and N2 plasma etching of 3D chitosan scaffolds. The present fabrication process for 3D scaffolds might be applied to a potential tool for preparing biocompatible scaffolds.

Nitrogen Addition Changes the Stoichiometry and Growth Rate of Different Organs in Pinus tabuliformis Seedlings

Directory of Open Access Journals (Sweden)

Hang Jing

2017-11-01

Full Text Available Background: Nitrogen (N deposition could influence plant stoichiometry and growth rate and thus alter the structure and function of the ecosystem. However, the mechanism by which N deposition changes the stoichiometry and relative growth rate (RGR of plant organs, especially roots with different diameters, is unclear.Methods: We created a gradient of N availability (0–22.4 g N m-2 year-1 for Pinus tabuliformis seedlings for 3 years and examined changes in the carbon (C:N:phosphorus (P ratios and RGRs of the leaves, stems, and roots with four diameter classes (finest roots, <0.5 mm; finer roots, 0.5–1 mm; middle roots, 1–2 mm; and coarse roots, >2 mm.Results: (1 N addition significantly increased the C and N contents of the leaves and whole roots, the C content of the stems, the N:P ratios of the leaves and stems, and the C:P ratio of the whole roots. (2 In the root system, the C:N ratio of the finest roots and the C:P ratios of the finest and finer roots significantly changed with N addition. The N:P ratios of the finest, finer, and middle roots significantly increased with increasing amount of N added. The stoichiometric responses of the roots were more sensitive to N addition than those of the other organs (3 The RGR of all the organs significantly increased at low N addition levels (2.8–11.2 g N m-2 year-1 but decreased at high N addition levels (22.4 g N m-2 year-1. (4 The RGRs of the whole seedlings and leaves were not significantly correlated with their N:P ratios at low and high N addition levels. By contrast, the RGRs of the stems and roots showed a significantly positive correlation with their own N:P ratio only at low N addition level.Conclusion: Addition of N affected plant growth by altering the contents of C and N; the ratios of C, N, and P; and the RGRs of the organs. RGR is correlated with the N:P ratios of the stems and roots at low N addition level but not at high N addition level. This finding is inconsistent with the

Interaction of oxides of nitrogen and aromatic hydrocarbons under simulated atmospheric conditions

International Nuclear Information System (INIS)

Obrien, R.J.; Green, P.J.; Doty, R.A.; Vanderzanden, J.W.; Easton, R.R.; Irwin, R.P.

1979-01-01

The reactions of nitrogen oxides with aromatic hydrocarbons under simulated atmospheric conditions are investigated. Gaseous reaction products formed when toluene is irradiated under simulated atmospheric conditions in the presence of nitrogen oxides were analyzed by gas chromatography. Reaction products detected include acetylene, water, acetaldehyde, acetone, toluene, benzaldehyde, ortho-, meta- and para-cresol, benzyl nitrate and meta- and para-nitrotoluene. Reaction mechanisms yielding the various products are illustrated. The assumption that all the nitrogen oxides observed to be lost from the reaction products can be accounted for by nitric acid formation in the absence of ozone formation is verified by a model in which the hydroxyl radical is assumed to be the only means of removing toluene. Under conditions in which ozone is formed, nitrogen oxide loss is accounted for by ozone formation in addition to nitric acid formation

Greenhouse gas emissions in salt marshes and their response to nitrogen loading

Science.gov (United States)

Tang, J.; Moseman-Valtierra, S.; Kroeger, K. D.; Morkeski, K.; Carey, J.

2015-12-01

Salt marshes play an important role in global and regional carbon and nitrogen cycling. Anthropogenic nitrogen loading may alter greenhouse gas (GHG, including CO2, CH4, and N2O) emissions and carbon sequestration in salt marshes. We measured GHG emissions biweekly for two growing seasons across a nitrogen-loading gradient of four Spartina salt marshes in Waquoit Bay, Massachusetts. In addition, we conducted nitrogen addition experiments in a pristine marsh by adding low and high nitrate bi-weekly during the summer. The GHG flux measurements were made in situ with a state-of-the-art mobile gas measurement system using the cavity ring down technology that consists of a CO2/CH4 analyzer (Picarro) and an N2O/CO analyzer (Los Gatos). We observed strong seasonal variations in greenhouse gas emissions. The differences in gas emissions across the nitrogen gradient (between 1 and 10 gN m-2y-1) were not significant, but strong pulse emissions of N2O were observed after nitrogen was artificially added to the marsh. We found that the studied salt marsh was a significant carbon sink (NEP ~ 380 gC m-2y-1). CH4 fluxes are 3 orders of magnitude less than CO2 fluxes in the salt marsh. Carbon fluxes are driven by light, salinity, tide, and temperature. We conclude that restoration or conservation of this carbon sink has a significant social benefit for carbon credit.

Habitat Management: A Tool to Modify Ecosystem Impacts of Nitrogen Deposition?

Directory of Open Access Journals (Sweden)

S.A. Power

2001-01-01

Full Text Available Atmospheric nitrogen deposition has been shown to affect both the structure and the function of heathland ecosystems. Heathlands are semi-natural habitats and, as such, undergo regular management by mowing or burning. Different forms of management remove more or less nutrients from the system, so habitat management has the potential to mitigate some of the effects of atmospheric deposition. Data from a dynamic vegetation model and two field experiments are presented. The first involves nitrogen addition following different forms of habitat management. The second tests the use of habitat management to promote heathland recovery after a reduction in nitrogen deposition. Both modelling and experimental approaches suggest that plant and microbial response to nitrogen is affected by management. Shoot growth and rates of decomposition were lowest in plots managed using more intensive techniques, including mowing with litter removal and a high temperature burn. Field data also indicate that ecosystem recovery from prolonged elevated inputs of nitrogen may take many years, or even decades, even after the removal of plant and litter nitrogen stores which accompanies the more intensive forms of habitat management.

Efficiency of open-hearth slag under different levels of nitrogen nutrition

Energy Technology Data Exchange (ETDEWEB)

Merzlyakov, L A

1979-01-01

Field and vegetational experiments have been carried out in the turf-podsolic soil in 1974-1977. Efficiency of open-hearth slag from the Izhevsk metallurgical plant depends on the level of nitrogen nutrition. The greatest addition from the slag is received at the elevated level of nitrogen nutrition. The maximum total addition for 3 years resulting from the use of slag in the field experiment constituted 54.5 double centner forage units which is higher than the addition resulting from lime by 52.7 %. Besides, the slag produced a positive effect upon the balance of the labelled /sup 15/N nitrogen in fertilizer: coefficient of the use of nitrogen in fertilizer during 2 years in the average increased by 7.1 and 11.2 % according to the nitrogen background of 230 and 460 mg/vessel.

Efficiency of open-hearth slag under different levels of nitrogen nutrition

International Nuclear Information System (INIS)

Merzlyakov, L.A.

1979-01-01

Field and vegetational experiments have been carried out in the turf-podsolic soil in 1974-1977. Efficiency of open-hearth slag from Izhevsk metallurgical plant depends on the level of nitrogen nutrition. The greatest addition from the slag is received at the elevated level of nitrogen nutrition. The maximum total addition for 3 years resulting from the use of slag in the field experiment constituted 54.5 double centner forage units which is higher than the addition resulting from lime by 52.7 %. Besides, the slag produced positive effect upon the balance of the labelled 15 N nitrogen in fertilizer: coefficient of the use of nitrogen in fertilizer during 2 years in the average increased by 7.1 and 11.2 % according to the nitrogen background of 230 and 460 mg/vessel

Improved creep and oxidation behavior of a martensitic 9Cr steel by the controlled addition of boron and nitrogen

Energy Technology Data Exchange (ETDEWEB)

Mayr, Peter [Massachusetts Institute of Technology, Cambridge, MA (United States). Dept. of Materials Science; Graz Univ. of Technology (Austria). Inst. of Material Science and Welding; Holzer, Ivan; Mendez-Martin, Francisca [Graz Univ. of Technology (Austria). Inst. of Material Science and Welding; Albu, Mihaela; Mitsche, Stefan [Graz Univ. of Technology (Austria). Inst. for Electron Microscopy; Gonzalez, Vanessa; Agueero, Alina [Instituto Nacional de Tecnica Aeroespacial, Torrejon de Ardoz (Spain)

2010-07-01

This manuscript gives an overview on recent developments of a martensitic steel grade based on 9Cr3W3CoVNb with controlled additions of boron and nitrogen. Alloy design by thermodynamic equilibrium calculations and calculation of boron-nitrogen solubility is discussed. Out of this alloy design process, two melts of a 9Cr3W3CoVNbBN steel were produced. The investigation focused on microstructural evolution during high temperature exposure, creep properties and oxidation resistance in steam at 650 C. Microstructural characterization of ''as-received'' and creep exposed material was carried out using conventional optical as well as advanced electron microscopic methods. Creep data at 650 was obtained at various stress levels. Longest-running specimens have reached more than 20,000 hours of testing time. In parallel, long-term oxidation resistance has been studied at 650 C in steam atmosphere up to 5,000 hours. Preliminary results of the extensive testing program on a 9Cr3W3CoVNbBN steel show significant improvement in respect to creep strength and oxidation resistance compared to the state-of-the-art 9 wt. % Cr martensitic steel grades. Up to current testing times, the creep strength is significantly beyond the +20% scatterband of standard grade P92 material. Despite the chromium content of 9 wt % the material exhibits excellent oxidation resistance. Steam exposed plain base material shows comparable oxidation behavior to coated material, and the corrosion rate of the boron-nitrogen controlled steel is much lower compared to standard 9 wt % Cr steel grades, P91 and P92. (orig.)

Reduction of Nitrogen Oxides Emissions from a Coal-Fired Boiler Unit

Science.gov (United States)

Zhuikov, Andrey V.; Feoktistov, Dmitry V.; Koshurnikova, Natalya N.; Zlenko, Lyudmila V.

2016-02-01

During combustion of fossil fuels a large amount of harmful substances are discharged into the atmospheres of cities by industrial heating boiler houses. The most harmful substances among them are nitrogen oxides. The paper presents one of the most effective technological solutions for suppressing nitrogen oxides; it is arrangement of circulation process with additional mounting of the nozzle directed into the bottom of the ash hopper. When brown high-moisture coals are burnt in the medium power boilers, generally fuel nitrogen oxides are produced. It is possible to reduce their production by two ways: lowering the temperature in the core of the torch or decreasing the excess-air factor in the boiler furnace. Proposed solution includes the arrangement of burning process with additional nozzle installed in the lower part of the ash hopper. Air supply from these nozzles creates vortex involving large unburned fuel particles in multiple circulations. Thereby time of their staying in the combustion zone is prolonging. The findings describe the results of the proposed solution; and recommendations for the use of this technological method are given for other boilers.

Development of commercial nitrogen-rich stainless steels

International Nuclear Information System (INIS)

Liljas, M.

1999-01-01

This paper reviews the development of nitrogen alloyed stainless steels. Nitrogen alloying of austenitic stainless steels started at an early stage and was to a large extent caused by nickel shortage. However, direct technical advantages such as increased strength of the nitrogen alloyed steels made them attractive alternatives to the current steels. It was not until the advent of the AOD (argon oxygen decarburisation) process in the late 1960s that nitrogen alloying could be controlled to such accuracy that it became successful commercially on a broader scale. The paper describes production aspects and how nitrogen addition influences microstructure and the resulting properties of austenitic and duplex stainless steels. For austenitic steels there are several reasons for nitrogen alloying. Apart from increasing strength nitrogen also improves structural stability, work hardening and corrosion resistance. For duplex steels nitrogen also has a decisive effect in controlling the microstructure during thermal cycles such as welding. (orig.)

Responses of secondary chemicals in sugar maple (Acer saccharum) seedlings to UV-B, springtime warming and nitrogen additions

Energy Technology Data Exchange (ETDEWEB)

Sager, E.P.S.; Hutchinson, T.C. [Trent Univ., Peterborough, ON (Canada). Environmental Studies

2006-10-15

Elevated UV-B radiation due to climatic change and ozone depletion may represent a significant springtime environmental stressor to germinating seedlings in temperate forest regions. This study aimed to determine the effects of UV-B, nitrogen (N) fertilization and climate warming on the concentrations of base cations and secondary metabolites in the foliage of sugar maple seedlings growing in acid or alkaline soils. The influence of measured flavonoids and phenolics on herbivore activity was examined, as well as the relationship between foliar concentrations of calcium (Ca); manganese (Mn); and N and the production of phenolic and flavonoid compounds. Experimental plots were established in mature hardwood forests in alkaline and acid soil locations in Bobcaygeon and Haliburton, Ontario. Pentagonal open-top chambers were used to lengthen the growing season and simulate an earlier spring. Ammonium nitrate was applied at a rate comparable with an additional deposition of 5 g N per m per year. Fertilizer was applied on 3 separate occasions. Ambient UV-B radiation was screened out with Mylar D polyester film. Sites, treatments and time of sampling had complex effects on foliar elemental chemistry, production of secondary compounds and herbivory. Foliar concentrations of individual phenols were higher in seedlings in the UV-B exclusion treatments. At both sites, removal of ambient UV-B led to increases in flavonoids and chlorogenic acid, and reduced herbivore activity. At Haliburton, ammonium nitrate fertilization led to further increases in foliar Mn. Nitrogen additions led to decreases in the concentrations of some flavonoids at both sites. It was concluded that the composition of the forest soil governs the response of seedlings when they are exposed to abiotic stressors. 63 refs., 5 tabs., 8 figs.

Emiliania Huxleyi (Prymnesiophyceae): Nitrogen-metabolism genes and their expression in response to external nitrogen souces

DEFF Research Database (Denmark)

Bruhn, Annette; LaRoche, Julie; Richardson, Katherine

2010-01-01

The availability and composition of dissolved nitrogen in ocean waters are factors that influence species composition in natural phytoplankton communities. The same factors affect the ratio of organic to inorganic carbon incorporation in calcifying species, such as the coccolithophore Emiliania...... huxleyi (Lohman) W. W. Hay et H. Mohler. E. huxleyi has been shown to thrive on various nitrogen sources, including dissolved organic nitrogen. Nevertheless, assimilation of dissolved nitrogen under nitrogen-replete and -limited conditions is not well understood in this ecologically important species....... In this study, the complete amino acid sequences for three functional genes involved in nitrogen metabolism in E. huxleyi were identified: a putative formamidase, a glutamine synthetase (GSII family), and assimilatory nitrate reductase. Expression patterns of the three enzymes in cells grown on inorganic...

Influence of the nitrogen gas addition in the Ar shielding gas on the erosion-corrosion of tube-to-tube sheet welds of hyper duplex stainless steel

International Nuclear Information System (INIS)

Kim, Hye-Jin; Jeon, Soon-Hyeok; Kim, Soon-Tae; Lee, In-Sung; Park, Yong-Soo

2014-01-01

Duplex stainless steels with nearly equal fraction of the ferrite(α) phase and austenite(γ) phase have been increasingly used for various applications such as power plants, desalination facilities due to their high resistance to corrosion, good weldability, and excellent mechanical properties. Hyper duplex stainless steel (HDSS) is defined as the future duplex stainless steel with a pitting resistance equivalent (PRE= wt.%Cr+3.3(wt.%Mo+0.5wt.%W)+30wt.%N) of above 50. However, when HDSS is welded with gas tungsten arc (GTA), incorporation of nitrogen in the Ar shielding gas are very important because the volume fraction of α-phase and γ-phase is changed and harmful secondary phases can be formed in the welded zone. In other words, the balance of corrosion resistance between two phases and reduction of Cr 2 N are the key points of this study. The primary results of this study are as follows. The addition of N 2 to the Ar shielding gas provides phase balance under weld-cooling conditions and increases the transformation temperature of the α-phase to γ-phase, increasing the fraction of γ-phase as well as decreasing the precipitation of Cr2N. In the anodic polarization test, the addition of nitrogen gas in the Ar shielding gas improved values of the electrochemical parameters, compared to the Pure Ar. Also, in the erosion-corrosion test, the HDSS welded with shielding gas containing N 2 decreased the weight loss, compared to HDSS welded with the Ar pure gas. This result showed the resistance of erosion-corrosion was increased due to increasing the fraction of γ-phase and the stability of passive film according to the addition N 2 gas to the Ar shielding gas. As a result, the addition of nitrogen gas to the shielding gas improved the resistance of erosion-corrosion

Influence of the nitrogen gas addition in the Ar shielding gas on the erosion-corrosion of tube-to-tube sheet welds of hyper duplex stainless steel

Energy Technology Data Exchange (ETDEWEB)

Kim, Hye-Jin; Jeon, Soon-Hyeok; Kim, Soon-Tae; Lee, In-Sung; Park, Yong-Soo [Yonsei University, Seoul (Korea, Republic of)

2014-03-15

Duplex stainless steels with nearly equal fraction of the ferrite(α) phase and austenite(γ) phase have been increasingly used for various applications such as power plants, desalination facilities due to their high resistance to corrosion, good weldability, and excellent mechanical properties. Hyper duplex stainless steel (HDSS) is defined as the future duplex stainless steel with a pitting resistance equivalent (PRE= wt.%Cr+3.3(wt.%Mo+0.5wt.%W)+30wt.%N) of above 50. However, when HDSS is welded with gas tungsten arc (GTA), incorporation of nitrogen in the Ar shielding gas are very important because the volume fraction of α-phase and γ-phase is changed and harmful secondary phases can be formed in the welded zone. In other words, the balance of corrosion resistance between two phases and reduction of Cr{sub 2}N are the key points of this study. The primary results of this study are as follows. The addition of N{sub 2} to the Ar shielding gas provides phase balance under weld-cooling conditions and increases the transformation temperature of the α-phase to γ-phase, increasing the fraction of γ-phase as well as decreasing the precipitation of Cr2N. In the anodic polarization test, the addition of nitrogen gas in the Ar shielding gas improved values of the electrochemical parameters, compared to the Pure Ar. Also, in the erosion-corrosion test, the HDSS welded with shielding gas containing N{sub 2} decreased the weight loss, compared to HDSS welded with the Ar pure gas. This result showed the resistance of erosion-corrosion was increased due to increasing the fraction of γ-phase and the stability of passive film according to the addition N{sub 2} gas to the Ar shielding gas. As a result, the addition of nitrogen gas to the shielding gas improved the resistance of erosion-corrosion.

Nitrogen retention across a gradient of 15N additions to an unpolluted temperate forest soil in Chile

Science.gov (United States)

Perakis, Steven S.; Compton, J.E.; Hedin, L.O.

2005-01-01

Accelerated nitrogen (N) inputs can drive nonlinear changes in N cycling, retention, and loss in forest ecosystems. Nitrogen processing in soils is critical to understanding these changes, since soils typically are the largest N sink in forests. To elucidate soil mechanisms that underlie shifts in N cycling across a wide gradient of N supply, we added 15NH415NO3 at nine treatment levels ranging in geometric sequence from 0.2 kg to 640 kg NA? ha-1A? yr-1 to an unpolluted old-growth temperate forest in southern Chile. We recovered roughly half of tracers in 0-25 cm of soil, primarily in the surface 10 cm. Low to moderate rates of N supply failed to stimulate N leaching, which suggests that most unrecovered 15N was transferred from soils to unmeasured sinks above ground. However, soil solution losses of nitrate increased sharply at inputs > 160 kg NA? ha-1A? yr-1, corresponding to a threshold of elevated soil N availability and declining 15N retention in soil. Soil organic matter (15N in soils at the highest N inputs and may explain a substantial fraction of the 'missing N' often reported in studies of fates of N inputs to forests. Contrary to expectations, N additions did not stimulate gross N cycling, potential nitrification, or ammonium oxidizer populations. Our results indicate that the nonlinearity in N retention and loss resulted directly from excessive N supply relative to sinks, independent of plant-soil-microbial feedbacks. However, N additions did induce a sharp decrease in microbial biomass C:N that is predicted by N saturation theory, and which could increase long-term N storage in soil organic matter by lowering the critical C:N ratio for net N mineralization. All measured sinks accumulated 15N tracers across the full gradient of N supply, suggesting that short-term nonlinearity in N retention resulted from saturation of uptake kinetics, not uptake capacity, in plant, soil, and microbial pools.

Hydrogen and Nitrogen Control in Ladle and Casting Operations

Energy Technology Data Exchange (ETDEWEB)

Richard J. Fruehan; Siddhartha Misra

2005-01-15

In recent years there has been an increasing demand to reduce and control the amount of dissolved gases in steel. Hydrogen and nitrogen are two of the most important gases which when dissolved in liquid steel affect its properties significantly. Several steelmaking additions have been investigated in this research for their effect on the hydrogen and nitrogen content of steels. It has been established that calcium hydroxide (hydrated lime) acts as a source of hydrogen. Carburizers, such as metallurgical coke, were found to result in no hydrogen pickup when added to liquid steel. Addition of petroleum coke, on the other hand, increased the hydrogen content of liquid steel. Ferroalloy such as medium carbon ferromanganese when added to the liquid iron was found to increase its nitrogen content, the increase being proportional to the amount of ferroalloy added. Similarly, addition of pitch coke, which had a significant nitrogen impurity, increased the nitrogen content of liquid iron. A mathematical model was developed to quantify the absorption of nitrogen and hydrogen from the air bubbles entrained during tapping of liquid steel. During the bottom stirring of liquid metal in a ladle, the inert gas escaping from the top displaces the slag layer and often forms an open eye. The absorption of atmospheric nitrogen through the spout eye was estimated for different slag thickness and gas flow rate. The ultimate goal of this research was to develop a comprehensive set of equations which could predict the nitrogen and hydrogen pickup from their various sources. Estimates of hydrogen and nitrogen pickup during the steel transfer operations such as tapping and ladle stirring and the predicted pickup from steelmaking additions were integrated into empirical equations. The comprehensive model is designed to predict the gas pickup under varying operating conditions such as the metal oxygen and sulfur content, the total tapping or stirring time, the stirring gas flow rate and the

Composting as a waste treatment technology: composting of sweet sorghum bagasse with different nitrogen sources

International Nuclear Information System (INIS)

Vicente, J.; Carrasco, J.E.; Negro, M.J.

1996-01-01

The purpose of this work is to study the aerobic solid fermentation of sweet sorghum bagasse in mixture with other additives as nitrogen sources to evaluate the utilization of this material as a substrate for composting. The characteristics of sweet sorghum bagasse, a material extremely low in nutrients as a consequence of sugar juice extraction but with a high organic carbon content, suggest that it may be possible to compost it with other organic wastes nitrogen rich, since this is an indispensable element for the protein synthesis of the microbial biomass which determines the fermentation process. Several additives, including different types of agricultural residues, residues from beer industries, industrial cellulases, an enzymatic commercial product for activation of composting, domestic sewage sludge as well as some inorganic sources, were used in the experiences. The additives were utilized in doses of 1,5 and 10% (in some case 0.1 and 1% by weight), and the final C/N ratio of the mixtures was adjusted to 30 with NH4NO3. taking to account the nitrogen content of the additives. The experiment was carried out in a constant chamber at 37degree centigree and lasted for two month. Best quality composts from a fertilizer perspective were obtained utilizing spillages and grain bagasse (beer industry residue) as a nitrogen sources. On the contrary the use of KNO3 as nitrogen source showed a relatively unfavourable effect on the composting. The results obtained show the suitability of sweet sorghum bagasse to be used as a carbon substrate for composting in mixtures with variety of nitrogen sources. (Author) 15 refs

Modelling the ecosystem effects of nitrogen deposition: Model of Ecosystem Retention and Loss of Inorganic Nitrogen (MERLIN

Directory of Open Access Journals (Sweden)

B. J. Cosby

1997-01-01

Full Text Available A catchment-scale mass-balance model of linked carbon and nitrogen cycling in ecosystems has been developed for simulating leaching losses of inorganic nitrogen. The model (MERLIN considers linked biotic and abiotic processes affecting the cycling and storage of nitrogen. The model is aggregated in space and time and contains compartments intended to be observable and/or interpretable at the plot or catchment scale. The structure of the model includes the inorganic soil, a plant compartment and two soil organic compartments. Fluxes in and out of the ecosystem and between compartments are regulated by atmospheric deposition, hydrological discharge, plant uptake, litter production, wood production, microbial immobilization, mineralization, nitrification, and denitrification. Nitrogen fluxes are controlled by carbon productivity, the C:N ratios of organic compartments and inorganic nitrogen in soil solution. Inputs required are: 1 temporal sequences of carbon fluxes and pools- 2 time series of hydrological discharge through the soils, 3 historical and current external sources of inorganic nitrogen; 4 current amounts of nitrogen in the plant and soil organic compartments; 5 constants specifying the nitrogen uptake and immobilization characteristics of the plant and soil organic compartments; and 6 soil characteristics such as depth, porosity, bulk density, and anion/cation exchange constants. Outputs include: 1 concentrations and fluxes of NO3 and NH4 in soil solution and runoff; 2 total nitrogen contents of the organic and inorganic compartments; 3 C:N ratios of the aggregated plant and soil organic compartments; and 4 rates of nitrogen uptake and immobilization and nitrogen mineralization. The behaviour of the model is assessed for a combination of land-use change and nitrogen deposition scenarios in a series of speculative simulations. The results of the simulations are in broad agreement with observed and hypothesized behaviour of nitrogen

Synthesis and review: Tackling the nitrogen management challenge: from global to local scales

Science.gov (United States)

Reis, Stefan; Bekunda, Mateete; Howard, Clare M.; Karanja, Nancy; Winiwarter, Wilfried; Yan, Xiaoyuan; Bleeker, Albert; Sutton, Mark A.

2016-12-01

One of the ‘grand challenges’ of this age is the anthropogenic impact exerted on the nitrogen cycle. Issues of concern range from an excess of fixed nitrogen resulting in environmental pressures for some regions, while for other regions insufficient fixed nitrogen affects food security and may lead to health risks. To address these issues, nitrogen needs to be managed in an integrated fashion, at a variety of scales (from global to local). Such management has to be based on a thorough understanding of the sources of reactive nitrogen released into the environment, its deposition and effects. This requires a comprehensive assessment of the key drivers of changes in the nitrogen cycle both spatially, at the field, regional and global scale and over time. In this focus issue, we address the challenges of managing reactive nitrogen in the context of food production and its impacts on human and ecosystem health. In addition, we discuss the scope for and design of management approaches in regions with too much and too little nitrogen. This focus issue includes several contributions from authors who participated at the N2013 conference in Kampala in November 2013, where delegates compiled and agreed upon the ‘Kampala Statement-for-Action on Reactive Nitrogen in Africa and Globally’. These contributions further underline scientifically the claims of the ‘Kampala Statement’, that simultaneously reducing pollution and increasing nitrogen available in the food system, by improved nitrogen management offers win-wins for environment, health and food security in both developing and developed economies. The specific messages conveyed in the Kampala Statement focus on improving nitrogen management (I), including the reduction of nitrogen losses from agriculture, industry, transport and energy sectors, as well as improving waste treatment and informing individuals and institutions (II). Highlighting the need for innovation and increased awareness among stakeholders (III

Effects of nitrogen additions on above- and belowground carbon dynamics in two tropical forests

Energy Technology Data Exchange (ETDEWEB)

Cusack, D.; Silver, W.L.; Torn, M.S.; McDowell, W.H.

2011-04-15

Anthropogenic nitrogen (N) deposition is increasing rapidly in tropical regions, adding N to ecosystems that often have high background N availability. Tropical forests play an important role in the global carbon (C) cycle, yet the effects of N deposition on C cycling in these ecosystems are poorly understood. We used a field N-fertilization experiment in lower and upper elevation tropical rain forests in Puerto Rico to explore the responses of above- and belowground C pools to N addition. As expected, tree stem growth and litterfall productivity did not respond to N fertilization in either of these Nrich forests, indicating a lack of N limitation to net primary productivity (NPP). In contrast, soil C concentrations increased significantly with N fertilization in both forests, leading to larger C stocks in fertilized plots. However, different soil C pools responded to N fertilization differently. Labile (low density) soil C fractions and live fine roots declined with fertilization, while mineral-associated soil C increased in both forests. Decreased soil CO2 fluxes in fertilized plots were correlated with smaller labile soil C pools in the lower elevation forest (R2 = 0.65, p\\0.05), and with lower live fine root biomass in the upper elevation forest (R2 = 0.90, p\\0.05). Our results indicate that soil C storage is sensitive to N deposition in tropical forests, even where plant productivity is not N-limited. The mineral-associated soil C pool has the potential to respond relatively quickly to N additions, and can drive increases in bulk soil C stocks in tropical forests.

Nitrogen Cycling in the Mycorrhizosphere: Multipartite Interactions and Plant Nitrogen Uptake Vary with Fertilization Legacy

Science.gov (United States)

Hestrin, R.; Lehmann, J.

2017-12-01

Soil microbes play an important role in rhizosphere nutrient cycling and plant productivity. In this study, the contributions of soil microbes to organic matter mineralization and plant nitrogen uptake were investigated using incubation and microcosm experiments. Microbial inocula included arbuscular mycorrhizal fungi and microbial communities sampled across a long-term gradient of nitrogen fertilization. Stable isotopes, nanoSIMS imaging, and phospholipid fatty acid analysis were used to track carbon and nitrogen movement from organic matter into microbes, mycorrhizal fungi, and plants. Results show that multipartite relationships between plants and microbes increased plant growth and access to nitrogen from organic matter, and that nitrogen fertilization history had a lasting effect on microbial contributions to fungal and plant nitrogen uptake. This research links rhizosphere ecology and land management with terrestrial biogeochemistry.

Long-term nitrogen addition affects the phylogenetic turnover of soil microbial community responding to moisture pulse.

Science.gov (United States)

Liu, Chi; Yao, Minjie; Stegen, James C; Rui, Junpeng; Li, Jiabao; Li, Xiangzhen

2017-12-13

How press disturbance (long-term) influences the phylogenetic turnover of soil microbial communities responding to pulse disturbances (short-term) is not fully known. Understanding the complex connections between the history of environmental conditions, assembly processes and microbial community dynamics is necessary to predict microbial response to perturbation. We started by investigating phylogenetic spatial turnover (based on DNA) of soil prokaryotic communities after long-term nitrogen (N) deposition and temporal turnover (based on RNA) of communities responding to pulse by conducting short-term rewetting experiments. The results showed that moderate N addition increased ecological stochasticity and phylogenetic diversity. In contrast, high N addition slightly increased homogeneous selection and decreased phylogenetic diversity. Examining the system with higher phylogenetic resolution revealed a moderate contribution of variable selection across the whole N gradient. The moisture pulse experiment showed that high N soils had higher rates of phylogenetic turnover across short phylogenetic distances and significant changes in community compositions through time. Long-term N input history influenced spatial turnover of microbial communities, but the dominant community assembly mechanisms differed across different N deposition gradients. We further revealed an interaction between press and pulse disturbances whereby deterministic processes were particularly important following pulse disturbances in high N soils.

Effects of nitrogen and hydrogen in argon shielding gas on bead profile, delta-ferrite and nitrogen contents of the pulsed GTAW welds of AISI 316L stainless steel

Energy Technology Data Exchange (ETDEWEB)

Viyanit, Ekkarut [National Metal and Materials Technology Center (MTEC), Pathaumthani (Thailand). Failure Analysis and Surface Technology Lab; Hartung, Fritz; Lothongkum, Gobboon [Chulalongkom University, Bangkok (Thailand). Dept. of Metallurgical Engineering,; Phakpeetinan, Panyasak; Chianpairot, Amnuysak

2016-08-01

The general effects of 1, 2, 3 and 4 vol.-% nitrogen and 1, 5 and 10 vol.-% hydrogen in argon shielding gas on weld bead profile (depth/width ratio: D/W) and the δ-ferrite content of AISI 316L pulsed GTAW welds were investigated. The limits for imperfections for the quality levels of welds were based on ISO 5817 B. The plates with a thickness of 6 mm were welded at the flat position and the bead on plate. Increasing hydrogen content in argon shielding gas increases the D/W ratio. Excessive hydrogen addition to argon shielding gas will result in incompletely filled groove and excessive penetration of weld. Increasing welding speed decreases the weld-metal volume and the D/W ratios. Nitrogen addition to argon shielding gas has no effect on the D/W ratio. The addition of a mixture of nitrogen and hydrogen to argon shielding gas on the D/W ratio does not show any interaction between them. An effect on the D/W ratio can be exclusively observed as a function of hydrogen content. Increasing hydrogen content in argon shielding gas increases the δ-ferrite content of weld metal. Increasing either nitrogen content in shielding gas or welding speed decreases the δ-ferrite content of weld metal. The nitrogen addition increases the weld metal nitrogen content, however, the hydrogen addition leads to a decrease of weld metal nitrogen content.

Assessment of free-living nitrogen fixing microorganisms for commercial nitrogen fixation. [economic analysis of ammonia production

Science.gov (United States)

Stokes, B. O.; Wallace, C. J.

1978-01-01

Ammonia production by Klebsiella pneumoniae is not economical with present strains and improving nitrogen fixation to its theoretical limits in this organism is not sufficient to achieve economic viability. Because the value of both the hydrogen produced by this organism and the methane value of the carbon source required greatly exceed the value of the ammonia formed, ammonia (fixed nitrogen) should be considered the by-product. The production of hydrogen by KLEBSIELLA or other anaerobic nitrogen fixers should receive additional study, because the activity of nitrogenase offers a significant improvement in hydrogen production. The production of fixed nitrogen in the form of cell mass by Azotobacter is also uneconomical and the methane value of the carbon substrate exceeds the value of the nitrogen fixed. Parametric studies indicate that as efficiencies approach the theoretical limits the economics may become competitive. The use of nif-derepressed microorganisms, particularly blue-green algae, may have significant potential for in situ fertilization in the environment.

A seasonal nitrogen deposition budget for Rocky Mountain National Park.

Science.gov (United States)

Benedict, K B; Carrico, C M; Kreidenweis, S M; Schichtel, B; Malm, W C; Collett, J L

2013-07-01

Nitrogen deposition is a concern in many protected ecosystems around the world, yet few studies have quantified a complete reactive nitrogen deposition budget including all dry and wet, inorganic and organic compounds. Critical loads that identify the level at which nitrogen deposition negatively affects an ecosystem are often defined using incomplete reactive nitrogen budgets. Frequently only wet deposition of ammonium and nitrate are considered, despite the importance of other nitrogen deposition pathways. Recently, dry deposition pathways including particulate ammonium and nitrate and gas phase nitric acid have been added to nitrogen deposition budgets. However, other nitrogen deposition pathways, including dry deposition of ammonia and wet deposition of organic nitrogen, still are rarely included. In this study, a more complete seasonal nitrogen deposition budget was constructed based on observations during a year-long study period from November 2008 to November 2009 at a location on the east side of Rocky Mountain National Park (RMNP), Colorado, USA. Measurements included wet deposition of ammonium, nitrate, and organic nitrogen, PM2.5 (particulate matter with an aerodynamic diameter less than 2.5 microm, nitrate, and ammonium) concentrations of ammonium, nitrate, and organic nitrogen, and atmospheric gas phase concentrations of ammonia, nitric acid, and NO2. Dry deposition fluxes were determined from measured ambient concentrations and modeled deposition velocities. Total reactive nitrogen deposition by all included pathways was found to be 3.65 kg N x ha(-1) yr(-1). Monthly deposition fluxes ranged from 0.06 to 0.54 kg N x ha(-1)yr(-1), with peak deposition in the month of July and the least deposition in December. Wet deposition of ammonium and nitrate were the two largest deposition pathways, together contributing 1.97 kg N x ha(-1)yr(-1) or 54% of the total nitrogen deposition budget for this region. The next two largest deposition pathways were wet

Potential nitrogen critical loads for northern Great Plains grassland vegetation

Science.gov (United States)

Symstad, Amy J.; Smith, Anine T.; Newton, Wesley E.; Knapp, Alan K.

2015-01-01

The National Park Service is concerned that increasing atmospheric nitrogen deposition caused by fossil fuel combustion and agricultural activities could adversely affect the northern Great Plains (NGP) ecosystems in its trust. The critical load concept facilitates communication between scientists and policy makers or land managers by translating the complex effects of air pollution on ecosystems into concrete numbers that can be used to inform air quality targets. A critical load is the exposure level below which significant harmful effects on sensitive elements of the environment do not occur. A recent review of the literature suggested that the nitrogen critical load for Great Plains vegetation is 10-25 kg N/ha/yr. For comparison, current atmospheric nitrogen deposition in NGP National Park Service (NPS) units ranges from ~4 kg N/ha/yr in the west to ~13 kg N/ha/yr in the east. The suggested critical load, however, was derived from studies far outside of the NGP, and from experiments investigating nitrogen loads substantially higher than current atmospheric deposition in the region.Therefore, to better determine the nitrogen critical load for sensitive elements in NGP parks, we conducted a four-year field experiment in three northern Great Plains vegetation types at Badlands and Wind Cave National Parks. The vegetation types were chosen because of their importance in NGP parks, their expected sensitivity to nitrogen addition, and to span a range of natural fertility. In the experiment, we added nitrogen at rates ranging from below current atmospheric deposition (2.5 kg N/ha/yr) to far above those levels but commensurate with earlier experiments (100 kg N/ha/yr). We measured the response of a variety of vegetation and soil characteristics shown to be sensitive to nitrogen addition in other studies, including plant biomass production, plant tissue nitrogen concentration, plant species richness and composition, non-native species abundance, and soil inorganic

Nitrogen fixation by free-living organisms in rice soils. Studies with 15N

International Nuclear Information System (INIS)

Rao, V.R.; Charyulu, P.B.B.N.; Nayak, D.N.; Ramakrishna, C.

1979-01-01

Heterotrophic nitrogen fixation as influenced by water regime, organic matter, combined nitrogen and pesticides was investigated in several Indian rice soils by means of the 15 N 2 tracer technique. Soil submergence accelerated nitrogen fixation. Addition of cellulose to both non-flooded and flooded soils enhanced nitrogen fixation. Under submerged conditions, addition of sucrose, glucose and malate in that order stimulated nitrogen fixation in alluvial soil, while only sucrose enhanced nitrogen fixation in laterite soil. Nitrogen fixation in flooded alluvial and laterite soils decreased with increasing concentration of combined nitrogen. Nitrogen fixation was appreciable in acid sulphate and saline soils under both flooded and non-flooded conditions, despite high salinity and acidity. Application of certain pesticides at rates equivalent to recommended field level greatly influenced nitrogen fixation in flooded rice soils. Additions of benomyl (carbamate fungicide) and carbofuran (methyl carbamate insecticide) to alluvial and laterite soils resulted in significant stimulation of nitrogen fixation. Gamma-BHC stimulated nitrogen fixation only in alluvial soil, with considerable inhibition in a laterite soil. Nitrogen fixation by Azospirillum lipoferum was investigated by 15 N 2 . Large variations in 15 N 2 incorporation by A. lipoferum isolated from the roots of several rice cultivars was observed. Specific lines of rice harbouring A. lipoferum with high nitrogenase activity might be selected. Nitrogen fixed by heterotrophic organisms in a complex system such as soil could not be evaluated precisely. Indigenous nitrogen fixation in a flooded soil would be in the range of 5-10 kg N/ha, increasable 3 to 4-fold by appropriate fertilizers and cultural practices

EFFECTS OF PROTEIN-XANTHOPHYLL (PX CONCENTRATE OF ALFALFA ADDITIVE TO CRUDE PROTEIN-REDUCED DIETS ON NITROGEN EXCRETION, GROWTH PERFORMANCE AND MEAT QUALITY OF PIGS

Directory of Open Access Journals (Sweden)

Eugeniusz GRELA

2009-06-01

Full Text Available The infl uence of protein-xanthophyll (PX concentrate of alfalfa supplement to crude protein-reduced diets was examined in relation to nitrogen excretion, performance parameters and pig meat quality. The investigations included 60 growers (PL x PLW x Duroc crossbreeds assigned to 3 groups. The conclusion is that there is a large potential to decrease nitrogen emission to the environment by 10% lowering of dietary crude protein intake along with reduced animal growth rate and elevated mixture utilization. Inclusion of a protein-xanthophyll concentrate (PX of alfalfa to the diet is likely to diminish disadvantageous productive parameters arising from limiting of total crude protein level in relation to the requirements of pigs feeding norms [1993]. At the same time, it improves feed nitrogen utilization and reduces noxious odour emissions from a piggery. The components of a protein-xanthophyll concentrate (PX contribute to increased liver and kidney weight.

A bibliometric review of nitrogen research in eutrophic lakes and reservoirs.

Science.gov (United States)

Yao, Xiaolong; Zhang, Yunlin; Zhang, Lu; Zhou, Yongqiang

2018-04-01

The global application of nitrogen is far greater than phosphorus, and it is widely involved in the eutrophication of lakes and reservoirs. We used a bibliometric method to quantitatively and qualitatively evaluate nitrogen research in eutrophic lakes and reservoirs to reveal research developments, current research hotspots, and emerging trends in this area. A total of 2695 articles in the past 25years from the online database of the Scientific Citation Index Expended (SCI-Expanded) were analyzed. Articles in this area increased exponentially from 1991 to 2015. Although the USA was the most productive country over the past 25years, China achieved the top position in terms of yearly publications after 2010. The most active keywords related to nitrogen in the past 25years included phosphorus, nutrients, sediment, chlorophyll-a, carbon, phytoplankton, cyanobacteria, water quality, modeling, and stable isotopes, based on analysis within 5-year intervals from 1991 to 2015 as well as the entire past 25years. In addition, researchers have drawn increasing attention to denitrification, climate change, and internal loading. Future trends in this area should focus on: (1) nutrient amounts, ratios, and major nitrogen sources leading to eutrophication; (2) nitrogen transformation and the bioavailability of different nitrogen forms; (3) nitrogen budget, mass balance model, control, and management; (4) ecosystem responses to nitrogen enrichment and reduction, as well as the relationships between these responses; and (5) interactions between nitrogen and other stressors (e.g., light intensity, carbon, phosphorus, toxic contaminants, climate change, and hydrological variations) in terms of eutrophication. Copyright © 2017. Published by Elsevier B.V.

Exhaustive Conversion of Inorganic Nitrogen to Nitrogen Gas Based on a Photoelectro-Chlorine Cycle Reaction and a Highly Selective Nitrogen Gas Generation Cathode.

Science.gov (United States)

Zhang, Yan; Li, Jinhua; Bai, Jing; Shen, Zhaoxi; Li, Linsen; Xia, Ligang; Chen, Shuai; Zhou, Baoxue

2018-02-06

A novel method for the exhaustive conversion of inorganic nitrogen to nitrogen gas is proposed in this paper. The key properties of the system design included an exhaustive photoelectrochemical cycle reaction in the presence of Cl - , in which Cl· generated from oxidation of Cl - by photoholes selectively converted NH 4 + to nitrogen gas and some NO 3 - or NO 2 - . The NO 3 - or NO 2 - was finally reduced to nitrogen gas on a highly selective Pd-Cu-modified Ni foam (Pd-Cu/NF) cathode to achieve exhaustive conversion of inorganic nitrogen to nitrogen gas. The results indicated total nitrogen removal efficiencies of 30 mg L -1 inorganic nitrogen (NO 3 - , NH 4 + , NO 3 - /NH 4 + = 1:1 and NO 2 - /NO 3 - /NH 4 + = 1:1:1) in 90 min were 98.2%, 97.4%, 93.1%, and 98.4%, respectively, and the remaining nitrogen was completely removed by prolonging the reaction time. The rapid reduction of nitrate was ascribed to the capacitor characteristics of Pd-Cu/NF that promoted nitrate adsorption in the presence of an electric double layer, eliminating repulsion between the cathode and the anion. Nitrate was effectively removed with a rate constant of 0.050 min -1 , which was 33 times larger than that of Pt cathode. This system shows great potential for inorganic nitrogen treatment due to the high rate, low cost, and clean energy source.

Farmer driven national monitoring of nitrogen concentrations in drainage water in Denmark

Science.gov (United States)

Piil, Kristoffer; Lemming, Camilla; Kolind Hvid, Søren; Knudsen, Leif

2014-05-01

addition to demonstrating that nitrogen retention around the drain depth occurs under certain geological conditions. In order to make management plans for individual catchments areas, this new information must be taken into account. In addition, there is a need to improve on the data presented here by measuring drain flow in order to quantify total nitrogen loss from drains. Both drain flow measurements and methods to include the evident variability in drainage water nitrogen concentrations are under way in other projects within the framework of the DNmark research alliance.

Effects of organic additives with oxygen- and nitrogen-containing functional groups on the negative electrolyte of vanadium redox flow battery

International Nuclear Information System (INIS)

Liu, Jianlei; Liu, Suqin; He, Zhangxing; Han, Huiguo; Chen, Yong

2014-01-01

DL-malic acid and L-aspartic acid are investigated as additives for the negative electrolyte of vanadium redox flow battery (VFRB) to improve its stability and electrochemical performance. The stability experiments indicate that the addition of L-aspartic acid into the 2 M V(III) electrolyte can stabilize the electrolyte by delaying its precipitation. The results of cyclic voltammetry and electrochemical impedance spectroscopy show that the V(III) electrolyte with both additives demonstrates enhanced electrochemical activity and reversibility. The introduction of DL-malic acid and L-aspartic acid can increase the diffusion coefficient of V(III) species and facilitate the charge transfer of V(III)/V(II) redox reaction. Between the two additives, the effect of L-aspartic acid is more remarkable. Moreover, the VFRB cell employing negative electrolyte with L-aspartic acid exhibits excellent cycling stability and achieves higher average energy efficiency (76.4%) compared to the pristine cell (73.8%). The comparison results with the cell employing L-aspartic acid pre-treated electrode confirm that L-aspartic acid in the electrolyte can modify the electrode by constantly providing oxygen- and nitrogen-containing groups, leading to the enhancement of electrochemical performance

Measuring and modeling the temporal dynamics of nitrogen balance in an experimental-scale paddy field

Science.gov (United States)

Tseng, C.; Lin, Y.

2013-12-01

Nitrogen balance involves many mechanisms and plays an important role to maintain the function of nature. Fertilizer application in agriculture activity is usually seen as a common and significant nitrogen input to environment. Improper fertilizer application on paddy field can result in great amount of various types of nitrogen losses. Hence, it is essential to understand and quantify the nitrogen dynamics in paddy field for fertilizer management and pollution control. In this study, we develop a model which considers major transformation processes of nitrogen (e.g. volatilization, nitrification, denitrification and plant uptake). In addition, we measured different types of nitrogen in plants, soil and water at plant growth stages in an experimental-scale paddy field in Taiwan. The measurement includes total nitrogen in plants and soil, and ammonium-N (NH4+-N), nitrate-N (NO3--N) and organic nitrogen in water. The measured data were used to calibrate the model parameters and validate the model for nitrogen balance simulation. The results showed that the model can accurately estimate the temporal dynamics of nitrogen balance in paddy field during the whole growth stage. This model might be helpful and useful for future fertilizer management and pollution control in paddy field.

Physico-chemical protection, rather than biochemical composition, governs the responses of soil organic carbon decomposition to nitrogen addition in a temperate agroecosystem.

Science.gov (United States)

Tan, Wenbing; Wang, Guoan; Huang, Caihong; Gao, Rutai; Xi, Beidou; Zhu, Biao

2017-11-15

The heterogeneous responses of soil organic carbon (SOC) decomposition in different soil fractions to nitrogen (N) addition remain elusive. In this study, turnover rates of SOC in different aggregate fractions were quantified based on changes in δ 13 C following the conversion of C 3 to C 4 vegetation in a temperate agroecosystem. The turnover of both total organic matter and specific organic compound classes within each aggregate fraction was inhibited by N addition. Moreover, the intensity of inhibition increases with decreasing aggregate size and increasing N addition level, but does not vary among chemical compound classes within each aggregate fraction. Overall, the response of SOC decomposition to N addition is dependent on the physico-chemical protection of SOC by aggregates and minerals, rather than the biochemical composition of organic substrates. The results of this study could help to understand the fate of SOC in the context of increasing N deposition. Copyright © 2017 Elsevier B.V. All rights reserved.

Reduction of Nitrogen Oxides Emissions from a Coal-Fired Boiler Unit

Directory of Open Access Journals (Sweden)

Zhuikov Andrey V.

2016-01-01

Full Text Available During combustion of fossil fuels a large amount of harmful substances are discharged into the atmospheres of cities by industrial heating boiler houses. The most harmful substances among them are nitrogen oxides. The paper presents one of the most effective technological solutions for suppressing nitrogen oxides; it is arrangement of circulation process with additional mounting of the nozzle directed into the bottom of the ash hopper. When brown high-moisture coals are burnt in the medium power boilers, generally fuel nitrogen oxides are produced. It is possible to reduce their production by two ways: lowering the temperature in the core of the torch or decreasing the excess-air factor in the boiler furnace. Proposed solution includes the arrangement of burning process with additional nozzle installed in the lower part of the ash hopper. Air supply from these nozzles creates vortex involving large unburned fuel particles in multiple circulations. Thereby time of their staying in the combustion zone is prolonging. The findings describe the results of the proposed solution; and recommendations for the use of this technological method are given for other boilers.

Will nitrogen deposition mitigate warming-increased soil respiration in a young subtropical plantation?

Science.gov (United States)

Xiaofei Liu; Zhijie Yang; Chengfang Lin; Christian P. Giardina; Decheng Xiong; Weisheng Lin; Shidong Chen; Chao Xu; Guangshui Chen; Jinsheng Xie; Yiqing Li; Yusheng Yang

2017-01-01

Global change such as climate warming and nitrogen (N) deposition is likely to alter terrestrial carbon (C) cycling, including soil respiration (Rs), the largest CO2 source from soils to the atmosphere. To examine the effects of warming, N addition and their interactions on Rs, we...

Fertilizer nitrogen fixation in plants and its transmutation in soils in case of annual application

International Nuclear Information System (INIS)

Shilova, E.I.; Smirnov, P.M.; Khon, N.I.

1974-01-01

Using certain combinations of 15 N labeled and unlabeled nitrogen-containing fertilizers data were obtained for direct determination of nitrogen balance in the year of fertilization and subsequently. Annual and total (for 3 years) increment in utilization of soil nitrogen resulting from repeated fertilization was also determined. Coefficient of nitrogen utilization by barley decreased over the 3-year period after additional application of ammonium sulfate while biological immobilization of nitrogen tended to increase. Application of straw during the first year of the experiment did not significantly affect the nitrogen balance in the following years. The total coefficient of nitrogen utilization for the 2 to 3-year period was higher than that of the first year while biological immobilization was relatively lower. Additional utilization of soil nitrogen as compared to the control was the same over the whole 3-year period; additional mobilization (annual and total) was relatively higher due to lower removal of soil nitrogen in the subsequent years. Utilization of previously immobilized nitrogen was higher in the case of repeated fertilization than without application of nitrogen fertilizers. The content of newly immobilized nitrogen during 3 years in the hydrolyzable undistilable fraction (nitrogen of bounded amino acids) was relatively lower and this was accompanied by the growth of hydrolyzable distilable and unhydrolyzable nitrogen

EarthN: A new Earth System Nitrogen Model

OpenAIRE

Goldblatt, Colin; Johnson, Benjamin

2018-01-01

The amount of nitrogen in the atmosphere, oceans, crust, and mantle have important ramifications for Earth’s biologic and geologic history. Despite this importance, the history and cycling of nitrogen in the Earth system is poorly constrained over time. For example, various models and proxies contrastingly support atmospheric mass stasis, net outgassing, or net ingassing over time. In addition, the amount available to and processing of nitrogen by organisms is intricately linked with and prov...

EarthN: A new Earth System Nitrogen Model

OpenAIRE

Johnson, Benjamin W.; Goldblatt, Colin

2018-01-01

The amount of nitrogen in the atmosphere, oceans, crust, and mantle have important ramifications for Earth's biologic and geologic history. Despite this importance, the history and cycling of nitrogen in the Earth system is poorly constrained over time. For example, various models and proxies contrastingly support atmospheric mass stasis, net outgassing, or net ingassing over time. In addition, the amount available to and processing of nitrogen by organisms is intricately linked with and prov...

The influence of sterilization on nitrogen-included ultrananocrystalline diamond for biomedical applications.

Science.gov (United States)

Tong, Wei; Tran, Phong A; Turnley, Ann M; Aramesh, Morteza; Prawer, Steven; Brandt, Milan; Fox, Kate

2016-04-01

Diamond has shown great potential in different biomedical applications, but the effects of sterilization on its properties have not been investigated. Here, we studied the influence of five sterilization techniques (solvent cleaning, oxygen plasma, UV irradiation, autoclave and hydrogen peroxide) on nitrogen-included ultrananocrystalline diamond. The chemical modification of the diamond surface was evaluated using X-ray photoelectron spectroscopy and water contact angle measurements. Different degrees of surface oxidation and selective sp(2) bonded carbon etching were found following all sterilization techniques, resulting in an increase of hydrophilicity. Higher viabilities of in vitro mouse 3T3 fibroblasts and rat cortical neuron cells were observed on oxygen plasma, autoclave and hydrogen peroxide sterilized diamond, which correlated with their higher hydrophilicity. By examination of apatite formation in simulated body fluid, in vivo bioactivity was predicted to be best on those surfaces which have been oxygen plasma treated and lowest on those which have been exposed to UV irradiation. The charge injection properties were also altered by the sterilization process and there appears to be a correlation between these changes and the degree of oxygen termination of the surface. We find that the modification brought by autoclave, oxygen plasma and hydrogen peroxide were most consistent with the use of N-UNCD in biological applications as compared to samples sterilized by solvent cleaning or UV exposure or indeed non-sterilized. A two-step process of sterilization by hydrogen peroxide following oxygen plasma treatment was then suggested. However, the final choice of sterilization technique will depend on the intended end application. Copyright © 2015 Elsevier B.V. All rights reserved.

Regulation of Carbon Flow by Nitrogen and Light in the Red Alga, Gelidium coulteri1

Science.gov (United States)

Macler, Bruce A.

1986-01-01

The red alga Gelidium coulteri Harv. photosynthetically fixed [14C] bicarbonate at high rates under defined conditions in unialgal laboratory culture. The fixation rate and flow of photosynthate into various end products were dependent on the nitrogen status of the tissue. Plants fed luxury levels of nitrogen (approximately 340 micromolar) showed fixation rates several-fold higher than those seen for plants starved for nitrogen. The addition of NO3− or NH4+ to such starved plants further inhibited fixation over at least the first several hours after addition. The majority of 14C after incubations of 30 minutes to 8 hours was found in the compounds floridoside, agar and floridean starch. In addition, amino acids and intermediate compounds of the reductive pentose phosphate pathway, glycolytic pathway and tricarboxylic acid cycle were detected. Nitrogen affected the partitioning of labeled carbon into these compounds. Plants under luxury nitrogen conditions had higher floridoside levels and markedly lower amounts of agar and starch than found in plants limited for nitrogen. Amino acid, phycobiliprotein and chlorophyll levels were also significantly higher in nitrogen-enriched plants. Addition of NO3− to starved plants led to an increase in floridoside, tricarboxylic acid cycle intermediates and amino acids within 1 hour and inhibited carbon flow into agar and starch. Carbon fixation in the dark was only 1 to 7% of that seen in the light. Dark fixation of [14C]bicarbonate yielded label primarily in tricarboxylic acid cycle intermediates, amino acids and polysaccharides. Nitrogen stimulated amino acid synthesis at the expense of agar and starch. Floridoside was only a minor component in the dark. Pulse-chase experiments, designed to show carbon turnover, indicated a 2-fold increase in labeling of agar over 96 hours of chase in the light. No increases were seen in the dark. Low molecular weight pools, including floridoside, decreased 2- to 5-fold over this period

Nitrogen fixation in Red Sea seagrass meadows

KAUST Repository

Abdallah, Malak

2017-05-01

Seagrasses are key coastal ecosystems, providing many ecosystem services. Seagrasses increase biodiversity as they provide habitat for a large set of organisms. In addition, their structure provides hiding places to avoid predation. Seagrasses can grow in shallow marine coastal areas, but several factors regulate their growth and distribution. Seagrasses can uptake different kinds of organic and inorganic nutrients through their leaves and roots. Nitrogen and phosphorous are the most important nutrients for seagrass growth. Biological nitrogen fixation is the conversion of atmospheric nitrogen into ammonia by diazotrophic bacteria. This process provides a significant source of nitrogen for seagrass growth. The nitrogen fixation is controlled by the nif genes which are found in diazotrophs. The main goal of the project is to measure nitrogen fixation rates on seagrass sediments, in order to compare among various seagrass species from the Red Sea. Moreover, we will compare the fixing rates of the Vegetated areas with the bare sediments. This project will help to ascertain the role of nitrogen fixing bacteria in the development of seagrass meadows.

Nitrogen Addition Exacerbates the Negative Effects of Low Temperature Stress on Carbon and Nitrogen Metabolism in Moss

Directory of Open Access Journals (Sweden)

Bin-Yang Liu

2017-08-01

Full Text Available Global environmental changes are leading to an increase in localized abnormally low temperatures and increasing nitrogen (N deposition is a phenomenon recognized worldwide. Both low temperature stress (LTS and excess N induce oxidative stress in plants, and excess N also reduces their resistance to LTS. Mosses are primitive plants that are generally more sensitive to alterations in environmental factors than vascular species. To study the combined effects of N deposition and LTS on carbon (C and N metabolism in moss, two moss species, Pogonatum cirratum subsp. fuscatum, and Hypnum plumaeforme, exposed to various concentrations of nitrate (KNO3 or ammonium (NH4Cl, were treated with or without LTS. C/N metabolism indices were then monitored, both immediately after the stress and after a short recovery period (10 days. LTS decreased the photosystem II (PSII performance index and inhibited non-cyclic photophosphorylation, ribulose-1,5-bisphosphate carboxylase, and glutamine synthetase activities, indicating damage to PSII and reductions in C/N assimilation in these mosses. LTS did not affect cyclic photophosphorylation, sucrose synthase, sucrose-phosphate synthase, and NADP-isocitrate dehydrogenase activities, suggesting a certain level of energy and C skeleton generation were maintained in the mosses to combat LTS; however, LTS inhibited the activity of glycolate oxidase. As predicted, N supply increased the sensitivity of the mosses to LTS, resulting in greater damage to PSII and a sharper decrease in C/N assimilation. After the recovery period, the performance of PSII and C/N metabolism, which were inhibited by LTS increased significantly, and were generally higher than those of control samples not exposed to LTS, suggesting overcompensation effects; however, N application reduced the extent of compensation effects. Both C and N metabolism exhibited stronger compensation effects in H. plumaeforme than in P. cirratum subsp. fuscatum. The

Effects of Nitrogen Addition on Leaf Decomposition of Single-Species and Litter Mixture in Pinus tabulaeformis Forests

Directory of Open Access Journals (Sweden)

Jinsong Wang

2015-12-01

Full Text Available The litter decomposition process is closely correlated with nutrient cycling and the maintenance of soil fertility in the forest ecosystem. In particular, the intense environmental concern about atmospheric nitrogen (N deposition requires a better understanding of its influence on the litter decomposition process. This study examines the responses of single-species litter and litter mixture decomposition processes to N addition in Chinese pine (Pinus tabulaeformis Carr. ecosystems. Chinese pine litter, Mongolian oak (Quercus mongolica Fisch. ex Ledeb. litter, and a pine–oak mixture were selected from a plantation and a natural forest of Chinese pine. Four N addition treatments, i.e., control (N0: 0 kg N ha−1·year−1, low-N (N1: 5 kg N ha−1·year−1, medium-N (N2: 10 kg N ha−1·year−1, and high-N (N3: 15 kg N ha−1·year−1, were applied starting May 2010. In the plantation, N addition significantly stimulated the decomposition of the Chinese pine litter. In the natural forest, N addition had variable effects on the decomposition of single-species litter and the litter mixture. A stimulatory effect of the high-N treatment on the Chinese pine litter decomposition could be attributed to a decrease in the substrate C:N ratio. However, an opposite effect was found for the Mongolian oak litter decomposition. The stimulating effect of N addition on the Chinese pine litter may offset the suppressive effect on the Mongolian oak litter, resulting in a neutral effect on the litter mixture. These results suggest that the different responses in decomposition of single-species litter and the litter mixture to N addition are mainly attributed to litter chemical composition. Further investigations are required to characterize the effect of long-term high-level N addition on the litter decomposition as N deposition is likely to increase rapidly in the region where this study was conducted.

Nitrogen from mountain to fjord - Annual report 1993; Nitrogen fra fjell til fjord. Aarsrapport 1993

Energy Technology Data Exchange (ETDEWEB)

Kaste, Oe; Bechmann, M; Toerset, K

1994-07-01

``Nitrogen from mountain to fjord`` is an interdisciplinary research programme which studies the nitrogen cycle from deposition to discharge into the sea. The project includes investigation of the nitrogen budgets for two catchments and selected areas of mountain, heath, forest, crop land and fresh water. The main purpose of the project is to increase the knowledge of uptake and runoff of nitrogen and thus to improve the prediction of future effects on soil, forest, fresh water and fjords. The activities are concentrated about two water courses in Norway: Bjerkreimsvassdraget and Aulivassdraget. In Bjerkreimsvassdraget the nitrate concentration changed only little from 1992 to 1993. Relatively large variations in the nitrate concentrations were found in the forest and heath areas of the system. In Aulivassdraget the nitrogen concentration has changed considerably in 1992 and 1993. The maximum concentration measured in the main river was 13.2 mg N/l. In autumn 1992 and spring 1993 much nitrogen remained in the soil after the poor harvest of 1992 and at that time much nitrogen was carried away by the runoff. 16 refs., 19 figs., 16 tabs.

Water- and plant-mediated responses of ecosystem carbon fluxes to warming and nitrogen addition on the Songnen grassland in northeast China.

Directory of Open Access Journals (Sweden)

Li Jiang

Full Text Available Understanding how grasslands are affected by a long-term increase in temperature is crucial to predict the future impact of global climate change on terrestrial ecosystems. Additionally, it is not clear how the effects of global warming on grassland productivity are going to be altered by increased N deposition and N addition.In-situ canopy CO(2 exchange rates were measured in a meadow steppe subjected to 4-year warming and nitrogen addition treatments. Warming treatment reduced net ecosystem CO(2 exchange (NEE and increased ecosystem respiration (ER; but had no significant impacts on gross ecosystem productivity (GEP. N addition increased NEE, ER and GEP. However, there were no significant interactions between N addition and warming. The variation of NEE during the four experimental years was correlated with soil water content, particularly during early spring, suggesting that water availability is a primary driver of carbon fluxes in the studied semi-arid grassland.Ecosystem carbon fluxes in grassland ecosystems are sensitive to warming and N addition. In the studied water-limited grassland, both warming and N addition influence ecosystem carbon fluxes by affecting water availability, which is the primary driver in many arid and semiarid ecosystems. It remains unknown to what extent the long-term N addition would affect the turn-over of soil organic matter and the C sink size of this grassland.

21 CFR 862.1515 - Nitrogen (amino-nitrogen) test system.

Science.gov (United States)

2010-04-01

... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Nitrogen (amino-nitrogen) test system. 862.1515... Systems § 862.1515 Nitrogen (amino-nitrogen) test system. (a) Identification. A nitrogen (amino-nitrogen) test system is a device intended to measure amino acid nitrogen levels in serum, plasma, and urine...

Nitrogen Out of the Bottle: The Challenge of Managing the Genie

Science.gov (United States)

Galloway, J. N.

2012-12-01

Human activity converts more N2 to reactive nitrogen (Nr; all nitrogen species other than N2) than do natural terrestrial processes (mostly biological nitrogen fixation (BNF) in unmanaged ecosystems). Most of the Nr is created as a consequence of food production, fossil fuel combustion and industry. The Haber-Bosch process, invented in the early 20th century, now provides a virtually inexhaustible supply of nitrogen fertilizer. This one invention is responsible for the existence of about half of the world's population. That's the good news. The other news is that most of this nitrogen (and additional amounts from fossil fuel combustion and industry) is lost to the environment where it has exceeded the ability of the environment to convert it back to unreactive N2. The accumulating Nr contributes to smog, greenhouse effect, ecosystem eutrophication, acid rain and loss of stratospheric ozone in a sequential manner—the nitrogen cascade. Collectively these changes alter climate, decrease air quality, and diminish ecosystem sustainability. The challenge is how do we manage the genie—make sure we get the benefits of nitrogen, while minimizing the problems it causes. The paper will layout the possible, the probable and the improbable (but if it occurred, would be transformative) options for nitrogen management. Included will be the role that a nation vs. a person should play. The paper will also give examples of success stories, where nitrogen losses to the environment have been decreased, without impacting the service being provided—food and energy production. The paper will conclude with a forecast to the future, based upon the RCP scenarios for 2100.

Uptake of fertilizer nitrogen and soil nitrogen by rice using 15N-labelled nitrogen fertilizer

International Nuclear Information System (INIS)

Reddy, K.R.; Patrick, W.H. Jr.

1980-01-01

Data from five field experiments using labelled nitrogen fertilizer were used to determine the relative effects of soil nitrogen and fertilizer nitrogen on rice yield. Yield of grain was closely correlated with total aboveground nitrogen uptake (soil + fertilizer), less closely correlated with soil nitrogen uptake and not significantly correlated with fertilizer nitrogen uptake. When yield increase rather than yield was correlated with fertilizer nitrogen uptake, the correlation coefficient was statistically significant. (orig.)

Nitrogen compounds behavior under irradiation environment

International Nuclear Information System (INIS)

Ichikawa, Nagayoshi; Takagi, Junichi; Yotsuyanagi, Tadasu

1991-01-01

Laboratory experiments were performed to evaluate nitrogen compounds behavior in liquid phase under irradiation environments. Nitrogen compounds take a chemical form of ammonium ion under reducing condition by gamma irradiation, whereas ammonium ions are rather stable even under oxidizing conditions. Key reactions were pointed out and their reaction rate constants and activation energies were estimated through computer code simulation. A reaction scheme for nitrogen compounds including protonate reaction was proposed. (author)

Improving maize productivity through tillage and nitrogen management

African Journals Online (AJOL)

Continuous cultivation of fields with same implement (cultivator) creates a hard pan in the subsoil which adversely affects crop productivity. In addition to tillage, nitrogen management is a key factor for better crop growth and yield. Impact of different tillage systems and nitrogen management on yield attributes and grain yield ...

Effects of phosphorus addition on nitrogen cycle and fluxes of N2O and CH4 in tropical tree plantation soils in Thailand

Directory of Open Access Journals (Sweden)

Taiki Mori

2017-04-01

Full Text Available An incubation experiment was conducted to test the effects of phosphorus (P addition on nitrous oxide (N2O emissions and methane (CH4 uptakes, using tropical tree plantation soils in Thailand. Soil samples were taken from five forest stands—Acacia auriculiformis, Acacia mangium, Eucalyptus camaldulensis, Hopea odorata, and Xylia xylocarpa—and incubated at 80% water holding capacity. P addition stimulated N2O emissions only in Xylia xylocarpa soils. Since P addition tended to increase net ammonification rates in Xylia xylocarpa soils, the stimulated N2O emissions were suggested to be due to the stimulated nitrogen (N cycle by P addition and the higher N supply for nitrification and denitrification. In other soils, P addition had no effects on N2O emissions or soil N properties, except that P addition tended to increase the soil microbial biomass N in Acacia auriculiformis soils. No effects of P addition were observed on CH4 uptakes in any soil. It is suggested that P addition on N2O and CH4 fluxes at the study site were not significant, at least under laboratory conditions.

Molecular nitrogen fixation and nitrogen cycle in nature

Energy Technology Data Exchange (ETDEWEB)

Virtanen, A I

1952-01-01

The origin of nitrogen oxides in the atmosphere is discussed. Evidently only a small proportion of the nitrate-and nitrite-nitrogen found in the precipitation is formed through electric discharges from molecular nitrogen, photochemical nitrogen fixation being probably of greater importance. Formation of nitrate nitrogen through atmospheric oxidation of nitrous oxide (N/sub 2/O) evaporating from the soil is also considered likely. Determination of nitrogen compounds at different altitudes is indispensable for gaining information of the N/sub 2/-fixation in the atmosphere and, in general, of the origin of nitrogen oxides and their decomposition. International cooperation is needed for this as well as for the quantitative determination of the nitrogen compounds removed from the soil by leaching and brought by waters into the seas.

Characterization of transient discharges under atmospheric-pressure conditions applying nitrogen photoemission and current measurements

International Nuclear Information System (INIS)

Keller, Sandra; Rajasekaran, Priyadarshini; Bibinov, Nikita; Awakowicz, Peter

2012-01-01

The plasma parameters such as electron distribution function and electron density of three atmospheric-pressure transient discharges namely filamentary and homogeneous dielectric barrier discharges in air, and the spark discharge of an argon plasma coagulation (APC) system are determined. A combination of numerical simulation as well as diagnostic methods including current measurement and optical emission spectroscopy (OES) based on nitrogen emissions is used. The applied methods supplement each other and resolve problems, which arise when these methods are used individually. Nitrogen is used as a sensor gas and is admixed in low amount to argon for characterizing the APC discharge. Both direct and stepwise electron-impact excitation of nitrogen emissions are included in the plasma-chemical model applied for characterization of these transient discharges using OES where ambiguity arises in the determination of plasma parameters under specific discharge conditions. It is shown that the measured current solves this problem by providing additional information useful for the determination of discharge-specific plasma parameters. (paper)

Human Decisions: Nitrogen Footprints and Environmental Effects

Science.gov (United States)

Leach, A. M.; Bleeker, A.; Galloway, J. N.; Erisman, J.

2012-12-01

Human consumption choices are responsible for growing losses of reactive nitrogen (Nr) to the environment. Once in the environment, Nr can cause a cascade of negative impacts such as smog, acid rain, coastal eutrophication, climate change, and biodiversity loss. Although all humans must consume nitrogen as protein, the food production process releases substantial Nr to the environment. This dilemma presents a challenge: how do we feed a growing population while reducing Nr? Although top-down strategies to reduce Nr losses (e.g., emissions controls) are necessary, the bottom-up strategies focusing on personal consumption patterns will be imperative to solve the nitrogen challenge. Understanding the effects of different personal choices on Nr losses and the environment is an important first step for this strategy. This paper will utilize information and results from the N-Calculator, a per capita nitrogen footprint model (www.N-Print.org), to analyze the impact of different food consumption patterns on a personal food nitrogen footprint and the environment. Scenarios will analyze the impact of the following dietary patterns on the average United States (28 kg Nr/cap/yr) food nitrogen footprint: 1) Consuming only the recommended protein as defined by the WHO and the USDA; 2) Reducing food waste by 50%; 3) Consuming a vegetarian diet; 4) Consuming a vegan diet; 5) Consuming a demitarian diet (replacing half of animal protein consumption with vegetable protein); 6) Substituting chicken (a more efficient animal protein) with beef (a less efficient animal protein); 7) Consuming sustainably-produced food; and 8) Using advanced wastewater treatment. Preliminary results suggest that widespread advanced wastewater treatment with nutrient removal technology and halving food waste would each reduce the US personal food nitrogen footprint by 13%. In addition, reducing protein consumption to the recommended levels would reduce the footprint by about 42%. Combining these measures

Impacts of delayed addition of N-rich and acidic substrates on nitrogen loss and compost quality during pig manure composting.

Science.gov (United States)

Jiang, Jishao; Kang, Kang; Chen, Dan; Liu, Ningning

2018-02-01

Delayed addition of Nitrogen (N)-rich and acidic substrates was investigated to evaluate its effects on N loss and compost quality during the composting process. Three different delayed adding methods of N-rich (pig manure) and acidic substrates (phosphate fertilizer and rotten apples) were tested during the pig manure and wheat straw is composting. The results showed that delayed addition of pig manure and acidic materials led two temperature peaks, and the durations of two separate thermophilic phase were closely related to the amount of pig manure. Delayed addition reduced total N loss by up to 14% when using superphosphate as acidic substrates, and by up to 12% when using rotten apples as acidic substrates, which is mainly due to the decreased NH 3 emissions. At the end of composting, delayed the addition of pig manure caused a significant increase in the HS (humus substance) content, and the highest HS content was observed when 70% of the pig manure was applied at day 0 and the remaining 30% was applied on day 27. In the final compost, the GI in all treatments almost reached the maturity requirement by exceeding 80%. The results suggest that delayed addition of animal manure and acidic substrates could prevent the N loss during composting and improve the compost quality. Copyright © 2017 Elsevier Ltd. All rights reserved.

Applications of nitrogen-alloyed stainless steels

Energy Technology Data Exchange (ETDEWEB)

Sundvall, J.; Olsson, J. [Avesta Sheffield AB (Sweden); Holmberg, B. [Avesta Welding AB (Sweden)

1999-07-01

A selected number of applications for different types of nitrogen-alloyed stainless steels are described. The applications and grades are based on how nitrogen improves different properties. Conventional austenitic grades of type 304 and 316 can be alloyed with nitrogen to increase the strength and to maintain the austenite stability after cold deformation when exposed to cryogenic temperatures. Such examples are presented. The addition of nitrogen to duplex grades of stainless steel such as 2205 improves the pitting resistance, among other things, and also enables faster reformation of the austenite in the heat affected zone. This means that heavy plate can be welded without pre-heating or post-weld heating. Such applications are covered. Modern highly alloyed austenitic stainless steels almost always contain nitrogen and all reasons for this are covered, i.e. to stabilise the austenite, to increase the strength, and to improve the pitting resistance. The increased strength is the characteristic exemplified the least, since the higher strength of duplex grades is well known, but examples on austenite stability and improved pitting resistance are presented. (orig.)

POPULATION DYNAMICS OF SMALL MAMMALS ACROSS A NITROGEN AMENDED LANDSCAPE

Science.gov (United States)

Biogeochemical alterations of the nitrogen cycle from anthropogenic activities could have significant effects on ecological processes at the population, community and ecosystem levels. Nitrogen additions in grasslands have produced qualitative and quantitative changes in vegetat...

Variation in nitrogen use efficiencies on Dutch dairy farms

NARCIS (Netherlands)

Daatselaar, Co Hg; Reijs, Joan R.; Oenema, Jouke; Doornewaard, Gerben J.; Aarts, Frans

2015-01-01

BACKGROUND: On dairy farms, the input of nutrients including nitrogen is higher than the output in products such as milk and meat. This causes losses of nitrogen to the environment. One of the indicators for the losses of nitrogen is the nitrogen use efficiency. In the Dutch Minerals Policy

Root distribution pattern and nitrogen uptake of some wheat and triticale germplasms in relation to rates and methods of nitrogen application

International Nuclear Information System (INIS)

Meena, N.L.; Seth, Jagdish

1975-01-01

A field experiment was conducted under irrigated conditions with four germplasms viz. Triticale(70-2), and wheat varieties HD 4502(durum), Kalyan Sona and Moti (aestivums) at the Indian Agricultural Research Institute Farm, New Delhi, during rabi season of 1972-73. The treatments comprised of three rates of nitrogen viz. 0,60 and 120 kg/ha and two methods of nitrogen application viz. (1) soil + foliar and (2) soil. The root distribution of the four germplasms, studied by 32 P injection technique was increased both vertically and horizontally with the addition of nitrogen. Root distribution of triticale was observed to be deep and spreading in habit, while durum proved to be shallow rooted and compact in nature. The total uptake of nitrogen was significantly increased with higher rates of nitrogen in all the germplasms. The maximum uptake of nitrogen was observed in the durum wheat. (author)

Growth responses of low-alpine dwarf-shrub heath species to nitrogen deposition and management

International Nuclear Information System (INIS)

Britton, Andrea J.; Fisher, Julia M.

2008-01-01

Nitrogen deposition is a continuing problem in European alpine regions. We hypothesised that, despite climatic limitations, low-alpine Calluna heathland would respond to nitrogen addition with increased shoot growth and flowering and that fire and grazing would modify responses. In a five-year study, 0-50 kg N ha -1 y -1 were added, combined with burning (+/-) and clipping (+/-). Calluna vulgaris responded with increased shoot extension, but effects on flowering were variable. Burning enhanced the positive effect of nitrogen addition and negative effects of clipping. Sub-dominant shrubs generally did not respond to nitrogen. C. vulgaris shoot extension was stimulated by nitrogen addition of 10 kg N ha -1 y -1 (above background) supporting suggestions that alpine heathlands are sensitive to low levels of nitrogen deposition. Increased C. vulgaris growth could negatively impact on important lichen components of this vegetation through increased shading and competition. Climatic factors constrain productivity in this community, but do not prevent rapid responses to nitrogen deposition by some species. - Low levels of N deposition increase productivity in alpine dwarf-shrub heath despite strong climatic constraints

The effect of Ti and Nb on nitrogen dissolution reaction in stainless steel melt

International Nuclear Information System (INIS)

Jang, Min Whan; Hong, In Kook; Pak, Jong Jin; Song, Hyo Seok; Lee, Yong Deuk

2002-01-01

A kinetic study of nitrogen dissolution in STS304 stainless steel melt containing Ti and Nb has been carried out at 1500 degree C using an induction furnace and a levitation melting furnace. At low O and S levels, the nitrogen dissolution rate showed the first-order kinetics being controlled by the mass transfer of nitrogen in the melt. Ti addition to STS304 stainless melt significantly retarded the nitrogen dissolution rate by the formation of solid Ti oxide layer adhered on the melt surface. Nb did not affect the rate of nitrogen dissolution. In the levitation melting experiment where the oxide layer was removed from the melt surface, Ti did not retard the nitrogen dissolution rate. Simultaneous addition of Ti and Al increased the dissolution rate by the formation of non-wetting Al 2 O 3 on the melt surface. A small addition of CaO-Al 2 O 3 synthetic flux to Ti containing melt was very effective to remove the oxide layer, hence to increase the nitrogen dissolution rate

The effect of Ti and Nb on nitrogen dissolution reaction in stainless steel melt

Energy Technology Data Exchange (ETDEWEB)

Jang, Min Whan; Hong, In Kook; Pak, Jong Jin [Hanyang Univ., Ansan (Korea, Republic of); Song, Hyo Seok; Lee, Yong Deuk [POSCO, Pohang (Korea, Republic of)

2002-03-01

A kinetic study of nitrogen dissolution in STS304 stainless steel melt containing Ti and Nb has been carried out at 1500 degree C using an induction furnace and a levitation melting furnace. At low O and S levels, the nitrogen dissolution rate showed the first-order kinetics being controlled by the mass transfer of nitrogen in the melt. Ti addition to STS304 stainless melt significantly retarded the nitrogen dissolution rate by the formation of solid Ti oxide layer adhered on the melt surface. Nb did not affect the rate of nitrogen dissolution. In the levitation melting experiment where the oxide layer was removed from the melt surface, Ti did not retard the nitrogen dissolution rate. Simultaneous addition of Ti and Al increased the dissolution rate by the formation of non-wetting Al{sub 2}O{sub 3} on the melt surface. A small addition of CaO-Al{sub 2}O{sub 3} synthetic flux to Ti containing melt was very effective to remove the oxide layer, hence to increase the nitrogen dissolution rate.

Effects of nitrogen additions on above- and belowground carbon dynamics in two tropical forests

Science.gov (United States)

Daniela F. Cusack; Whendee L. Silver; Margaret S. Torn; William H. McDowell

2011-01-01

Anthropogenic nitrogen (N) deposition is increasing rapidly in tropical regions, adding N to ecosystems that often have high background N availability. Tropical forests play an important role in the global carbon (C) cycle, yet the effects of N deposition on C cycling in these ecosystems are poorly understood. We used a field N-fertilization experiment in lower and...

Seasonal Patterns of Soil Respiration and Related Soil Biochemical Properties under Nitrogen Addition in Winter Wheat Field.

Science.gov (United States)

Liang, Guopeng; Houssou, Albert A; Wu, Huijun; Cai, Dianxiong; Wu, Xueping; Gao, Lili; Li, Jing; Wang, Bisheng; Li, Shengping

2015-01-01

Understanding the changes of soil respiration under increasing N fertilizer in cropland ecosystems is crucial to accurately predicting global warming. This study explored seasonal variations of soil respiration and its controlling biochemical properties under a gradient of Nitrogen addition during two consecutive winter wheat growing seasons (2013-2015). N was applied at four different levels: 0, 120, 180 and 240 kg N ha(-1) year(-1) (denoted as N0, N12, N18 and N24, respectively). Soil respiration exhibited significant seasonal variation and was significantly affected by soil temperature with Q10 ranging from 2.04 to 2.46 and from 1.49 to 1.53 during 2013-2014 and 2014-2015 winter wheat growing season, respectively. Soil moisture had no significant effect on soil respiration during 2013-2014 winter wheat growing season but showed a significant and negative correlation with soil respiration during 2014-2015 winter wheat growing season. Soil respiration under N24 treatment was significantly higher than N0 treatment. Averaged over the two growing seasons, N12, N18 and N24 significantly increased soil respiration by 13.4, 16.4 and 25.4% compared with N0, respectively. N addition also significantly increased easily extractable glomalin-related soil protein (EEG), soil organic carbon (SOC), total N, ammonium N and nitrate N contents. In addition, soil respiration was significantly and positively correlated with β-glucosidase activity, EEG, SOC, total N, ammonium N and nitrate N contents. The results indicated that high N fertilization improved soil chemical properties, but significantly increased soil respiration.

Urea and Ammonia Metabolism and the Control of Renal Nitrogen Excretion

Science.gov (United States)

Mitch, William E.; Sands, Jeff M.

2015-01-01

Renal nitrogen metabolism primarily involves urea and ammonia metabolism, and is essential to normal health. Urea is the largest circulating pool of nitrogen, excluding nitrogen in circulating proteins, and its production changes in parallel to the degradation of dietary and endogenous proteins. In addition to serving as a way to excrete nitrogen, urea transport, mediated through specific urea transport proteins, mediates a central role in the urine concentrating mechanism. Renal ammonia excretion, although often considered only in the context of acid-base homeostasis, accounts for approximately 10% of total renal nitrogen excretion under basal conditions, but can increase substantially in a variety of clinical conditions. Because renal ammonia metabolism requires intrarenal ammoniagenesis from glutamine, changes in factors regulating renal ammonia metabolism can have important effects on glutamine in addition to nitrogen balance. This review covers aspects of protein metabolism and the control of the two major molecules involved in renal nitrogen excretion: urea and ammonia. Both urea and ammonia transport can be altered by glucocorticoids and hypokalemia, two conditions that also affect protein metabolism. Clinical conditions associated with altered urine concentrating ability or water homeostasis can result in changes in urea excretion and urea transporters. Clinical conditions associated with altered ammonia excretion can have important effects on nitrogen balance. PMID:25078422

Enzymology and ecology of the nitrogen cycle.

Science.gov (United States)

Martínez-Espinosa, Rosa María; Cole, Jeffrey A; Richardson, David J; Watmough, Nicholas J

2011-01-01

The nitrogen cycle describes the processes through which nitrogen is converted between its various chemical forms. These transformations involve both biological and abiotic redox processes. The principal processes involved in the nitrogen cycle are nitrogen fixation, nitrification, nitrate assimilation, respiratory reduction of nitrate to ammonia, anaerobic ammonia oxidation (anammox) and denitrification. All of these are carried out by micro-organisms, including bacteria, archaea and some specialized fungi. In the present article, we provide a brief introduction to both the biochemical and ecological aspects of these processes and consider how human activity over the last 100 years has changed the historic balance of the global nitrogen cycle.

Nitrogen Addition and Warming Independently Influence the Belowground Micro-Food Web in a Temperate Steppe

NARCIS (Netherlands)

Li, Q.; Bai, H.; Liang, W.; Xia, J.; Wan, S.; Putten, van der W.H.

2013-01-01

Climate warming and atmospheric nitrogen (N) deposition are known to influence ecosystem structure and functioning. However, our understanding of the interactive effect of these global changes on ecosystem functioning is relatively limited, especially when it concerns the responses of soils and soil

Euthanasia of Small Animals with Nitrogen; Comparison with Intravenous Pentobarbital

OpenAIRE

Quine, John P.; Buckingham, William; Strunin, Leo

1988-01-01

Intravenous pentobarbital (with or without addition of saturated potassium chloride) was compared with nitrogen gas exposure for euthanasia of small animals (dogs, cats, and rabbits) in a humane society environment. Initially, electrocardiographic) and electroencephalographic monitoring were used to establish the time of death in presedated animals given either pentobarbital or exposed to nitrogen; later, nitrogen euthanasia alone was studied. Sedation with acepromazine delayed the effects of...

Simple additive simulation overestimates real influence: altered nitrogen and rainfall modulate the effect of warming on soil carbon fluxes.

Science.gov (United States)

Ni, Xiangyin; Yang, Wanqin; Qi, Zemin; Liao, Shu; Xu, Zhenfeng; Tan, Bo; Wang, Bin; Wu, Qinggui; Fu, Changkun; You, Chengming; Wu, Fuzhong

2017-08-01

Experiments and models have led to a consensus that there is positive feedback between carbon (C) fluxes and climate warming. However, the effect of warming may be altered by regional and global changes in nitrogen (N) and rainfall levels, but the current understanding is limited. Through synthesizing global data on soil C pool, input and loss from experiments simulating N deposition, drought and increased precipitation, we quantified the responses of soil C fluxes and equilibrium to the three single factors and their interactions with warming. We found that warming slightly increased the soil C input and loss by 5% and 9%, respectively, but had no significant effect on the soil C pool. Nitrogen deposition alone increased the soil C input (+20%), but the interaction of warming and N deposition greatly increased the soil C input by 49%. Drought alone decreased the soil C input by 17%, while the interaction of warming and drought decreased the soil C input to a greater extent (-22%). Increased precipitation stimulated the soil C input by 15%, but the interaction of warming and increased precipitation had no significant effect on the soil C input. However, the soil C loss was not significantly affected by any of the interactions, although it was constrained by drought (-18%). These results implied that the positive C fluxes-climate warming feedback was modulated by the changing N and rainfall regimes. Further, we found that the additive effects of [warming × N deposition] and [warming × drought] on the soil C input and of [warming × increased precipitation] on the soil C loss were greater than their interactions, suggesting that simple additive simulation using single-factor manipulations may overestimate the effects on soil C fluxes in the real world. Therefore, we propose that more multifactorial experiments should be considered in studying Earth systems. © 2016 John Wiley & Sons Ltd.

Evaluation of the Impact of Alveolar Nitrogen Excretion on Indices Derived from Multiple Breath Nitrogen Washout

Science.gov (United States)

Nielsen, Niklas; Nielsen, Jorgen G.; Horsley, Alex R.

2013-01-01

Background A large body of evidence has now accumulated describing the advantages of multiple breath washout tests over conventional spirometry in cystic fibrosis (CF). Although the majority of studies have used exogenous sulphur hexafluoride (SF6) as the tracer gas this has also led to an increased interest in nitrogen washout tests, despite the differences between these methods. The impact of body nitrogen excreted across the alveoli has previously been ignored. Methods A two-compartment lung model was developed that included ventilation heterogeneity and dead space (DS) effects, but also incorporated experimental data on nitrogen excretion. The model was used to assess the impact of nitrogen excretion on washout progress and accuracy of functional residual capacity (FRC) and lung clearance index (LCI) measurements. Results Excreted nitrogen had a small effect on accuracy of FRC (1.8%) in the healthy adult model. The error in LCI calculated with true FRC was greater (6.3%), and excreted nitrogen contributed 21% of the total nitrogen concentration at the end of the washout. Increasing DS and ventilation heterogeneity both caused further increase in measurement error. LCI was increased by 6–13% in a CF child model, and excreted nitrogen increased the end of washout nitrogen concentration by 24–49%. Conclusions Excreted nitrogen appears to have complex but clinically significant effects on washout progress, particularly in the presence of abnormal gas mixing. This may explain much of the previously described differences in washout outcomes between SF6 and nitrogen. PMID:24039916

Effect of nitrogen on the corrosion behavior of austenitic stainless steel in chloride solutions

International Nuclear Information System (INIS)

Ghanem, Wafaa A.

2004-01-01

The effect of partial replacement of nickel with nitrogen on the mechanism of localized corrosion resistance and re-passivation for nitrogen-bearing stainless steel was investigated using anodic potentiodynamic polarization technique. The solutions used for this study contained 0.0, 0.05 and 0.33 M Fe 3+ for solutions I, II and III respectively, in a total Cl - ion concentration 1 M. The pitting attack was found to be retarded by nitrogen addition and the samples were able to passivate as the nitrogen increase. Addition of nitrogen allows decreasing the percentage of Ni, but to a certain limit. Nitrogen is adsorbed on the interface of the metal oxide and results in repulsion of Cl - ions. Moreover, it reacts with H + ions in the solution leading to higher pH, which explains the retardation effect of nitrogen to corrosion. (author)

A detailed kinetic mechanism including methanol and nitrogen pollutants relevant to the gas-phase combustion and pyrolysis of biomass-derived fuels

Energy Technology Data Exchange (ETDEWEB)

Coda Zabetta, Edgardo; Hupa, Mikko [Aabo Akademi Process Chemistry Centre, Piispankatu 8, FI-20500 Turku (Finland)

2008-01-15

A detailed chemical kinetic mechanism for the simulation of the gas-phase combustion and pyrolysis of biomass-derived fuels was compiled by assembling selected reaction subsets from existing mechanisms (parents). The mechanism, here referred to as ''AaA,'' includes reaction subsets for the oxidation of hydrogen (H{sub 2}), carbon monoxide (CO), light hydrocarbons (C{sub 1} and C{sub 2}), and methanol (CH{sub 3}OH). The mechanism also takes into account reaction subsets of nitrogen pollutants, including the reactions relevant to staged combustion, reburning, and selective noncatalytic reduction (SNCR). The AaA mechanism was validated against suitable experimental data from the literature. Overall, the AaA mechanism gave more accurate predictions than three other mechanisms of reference, although the reference mechanisms performed better occasionally. The predictions from AaA were also found to be consistent with the predictions of its parent mechanisms within most of their range of validity, thus transferring the validity of the parents to the inheriting mechanism (AaA). In parametric studies the AaA mechanism predicted that the effect of methanol on combustion and pollutants is often similar to that of light hydrocarbons, but it also showed that there are important exceptions, thus suggesting that methanol should be taken into account when simulating biomass combustion. To our knowledge, the AaA mechanism is currently the only mechanism that accounts for the chemistry of methanol and nitrogen relevant to the gas-phase combustion and pyrolysis of biomass-derived fuels. (author)

Reduced turning frequency and delayed poultry manure addition reduces N loss from sugarcane compost.

Science.gov (United States)

Bryndum, S; Muschler, R; Nigussie, A; Magid, J; de Neergaard, A

2017-07-01

Composting is an effective method to recycle biodegradable waste as soil amendment in smallholder farming systems. Although all essential plant nutrients are found in compost, a substantial amount of nitrogen is lost during composting. This study therefore investigated the potential of reducing N losses by (i) delaying the addition of nitrogen-rich substrates (i.e. poultry manure), and (ii) reducing the turning frequency during composting. Furthermore, we tested the effect of compost application method on nitrogen mineralization. Sugarcane-waste was composted for 54days with addition of poultry manure at the beginning (i.e. early addition) or after 21days of composting (delayed addition). The compost pile was then turned either every three or nine days. Composts were subsequently applied to soil as (i) homogeneously mixed, or (ii) stratified, and incubated for 28days to test the effect of compost application on nitrogen mineralization. The results showed that delayed addition of poultry manure reduced total nitrogen loss by 33% and increased mineral nitrogen content by >200% compared with early addition. Similarly, less frequent turning reduced total N loss by 12% compared with frequent turning. Stratified placement of compost did not enhance N mineralization compared to a homogeneous mixing. Our results suggested that simple modifications of the composting process (i.e. delayed addition and/or turning frequency) could significantly reduce N losses and improve the plant-nutritional value of compost. Copyright © 2017 Elsevier Ltd. All rights reserved.

A comparative evaluation of nitrogen compounds in petroleum distillates

Energy Technology Data Exchange (ETDEWEB)

Singh, Dheer; Chopra, Anju; Patel, Mitra Bhanu; Sarpal, Amarjit Singh [Indian Oil Corporation Limited, Faridabad (India). Research and Development Centre

2011-07-15

Although the concentration of nitrogen compounds in crude oil is relatively low, they can become more concentrated in petroleum distillates and poison the catalysts used in refining processes. They cause undesirable deposits, color formation and odor in products; they also contribute to air pollution and some are highly carcinogenic. The poisoned catalyst becomes deactivated for hydrodesulfurization and unable to remove sulfur from middle distillates. In order to understand the effect on catalytic processes, it is desirable to identify the nitrogen compounds in various petroleum distillates. This paper compares the nitrogen species profiles in different petroleum distillates using a nitrogen chemiluminescence detector. In addition, four different petroleum distillate samples from different refineries were analyzed to find the variation in their nitrogen profiles. The nitrogen compounds in petroleum distillate samples were identified as anilines, quinolines, indoles, and carbazoles and their alkyl derivatives. Quantitation was carried out against known reference standards. The quantitative data were compared to the total nitrogen content determined by elemental analysis. (orig.)

Clinoptilolite zeolite influence on nitrogen in a manure-amended sandy agricultural soil

Science.gov (United States)

Development of best management practices can help improve inorganic nitrogen (N) availability to plants and reduce nitrate-nitrogen (NO3-N) leaching in soils. This study was conducted to determine the influence of the zeolite mineral clinoptilolite (CL) additions on NO3-N and ammonium-nitrogen (NH4-...

Nitrogen narcosis induced by repetitive hyperbaric nitrogen oxygen mixture exposure impairs long-term cognitive function in newborn mice.

Directory of Open Access Journals (Sweden)

Bin Peng

Full Text Available Human beings are exposed to compressed air or a nitrogen-oxygen mixture, they will produce signs and symptoms of nitrogen narcosis such as amnesia or even loss of memory, which may be disappeared once back to the normobaric environment. This study was designed to investigate the effect of nitrogen narcosis induced by repetitive hyperbaric nitrogen-oxygen mixture exposure on long-term cognitive function in newborn mice and the underlying mechanisms. The electroencephalogram frequency was decreased while the amplitude was increased in a pressure-dependent manner during 0.6, 1.2, 1.8 MPa (million pascal nitrogen-oxygen mixture exposures in adult mice. Nitrogen narcosis in postnatal days 7-9 mice but not in adult mice induced by repetitive hyperbaric exposure prolonged the latency to find the platform and decreased the number of platform-site crossovers during Morris water maze tests, and reduced the time in the center during the open field tests. An increase in the expression of cleaved caspase-3 in the hippocampus and cortex were observed immediately on the first day after hyperbaric exposure, and this lasted for seven days. Additionally, nitrogen narcosis induced loss of the dendritic spines but not of the neurons, which may mainly account for the cognitive dysfunction. Nitrogen narcosis induced long-term cognitive and emotional dysfunction in the postnatal mice but not in the adult mice, which may result from neuronal apoptosis and especially reduction of dendritic spines of neurons.

Nitrogenous air pollutants: Chemical and biological implications

International Nuclear Information System (INIS)

Grosjean, D.

1979-01-01

Theoretical and experimental studies on the health effects and chemistry of gaseous and particulate nitrogenous air pollutants are presented. Specific topics include Fourier transform infrared studies of nitrogenous compounds, the mechanism of peroxynitric acid formation, N-nitroso compounds in the air, the chemical transformations of nitrogen oxides during the sampling of combustion products, the atmospheric chemistry of peroxy nitrates, and the effects of nitrogen dioxide on lung metabolism. Attention is also given to the interaction of nitrogen oxides and aromatic hydrocarbons under simulated atmospheric conditions, the characterization of particulate amines, the role of ammonia in atmospheric aerosol chemistry, the relationship between sulfates and nitrates and tropospheric measurements of nitric acid vapor and particulate nitrates

Study on the Conversion of Fuel Nitrogen Into NOx

Directory of Open Access Journals (Sweden)

Raminta Plečkaitienė

2011-12-01

Full Text Available The aim of this work is to investigate NOx regularities combusting fuels having high concentration of nitrogen and to develop methods that will reduce the conversion of fuel nitrogen into NOx. There are three solutions to reducing NOx concentration: the combustion of fuel mixing it with other types of “clean” fuel containing small amounts of nitrogen, laundering fuel and the combustion of fuel using carbon additives. These solutions can help with reducing the amount of nitrogen in the wood waste of furniture by about 30% by washing fuel with water. Therefore, NOx value may decrease by about 35%.Article in Lithuanian

Transformation of saturated nitrogen-containing heterocyclic compounds by microorganisms.

Science.gov (United States)

Parshikov, Igor A; Silva, Eliane O; Furtado, Niege A J C

2014-02-01

The saturated nitrogen-containing heterocyclic compounds include many drugs and compounds that may be used as synthons for the synthesis of other pharmacologically active substances. The need for new derivatives of saturated nitrogen-containing heterocycles for organic synthesis, biotechnology and the pharmaceutical industry, including optically active derivatives, has increased interest in microbial synthesis. This review provides an overview of microbial technologies that can be valuable to produce new derivatives of saturated nitrogen-containing heterocycles, including hydroxylated derivatives. The chemo-, regio- and enantioselectivity of microbial processes can be indispensable for the synthesis of new compounds. Microbial processes carried out with fungi, including Beauveria bassiana, Cunninghamella verticillata, Penicillium simplicissimum, Aspergillus niger and Saccharomyces cerevisiae, and bacteria, including Pseudomonas sp., Sphingomonas sp. and Rhodococcus erythropolis, biotransform many substrates efficiently. Among the biological activities of saturated nitrogen-containing heterocyclic compounds are antimicrobial, antitumor, antihypertensive and anti-HIV activities; some derivatives are effective for the treatment and prevention of malaria and trypanosomiasis, and others are potent glycosidase inhibitors.

Seasonal Patterns of Soil Respiration and Related Soil Biochemical Properties under Nitrogen Addition in Winter Wheat Field

Science.gov (United States)

Liang, Guopeng; Houssou, Albert A.; Wu, Huijun; Cai, Dianxiong; Wu, Xueping; Gao, Lili; Li, Jing; Wang, Bisheng; Li, Shengping

2015-01-01

Understanding the changes of soil respiration under increasing N fertilizer in cropland ecosystems is crucial to accurately predicting global warming. This study explored seasonal variations of soil respiration and its controlling biochemical properties under a gradient of Nitrogen addition during two consecutive winter wheat growing seasons (2013–2015). N was applied at four different levels: 0, 120, 180 and 240 kg N ha-1 year-1 (denoted as N0, N12, N18 and N24, respectively). Soil respiration exhibited significant seasonal variation and was significantly affected by soil temperature with Q10 ranging from 2.04 to 2.46 and from 1.49 to 1.53 during 2013–2014 and 2014–2015 winter wheat growing season, respectively. Soil moisture had no significant effect on soil respiration during 2013–2014 winter wheat growing season but showed a significant and negative correlation with soil respiration during 2014–2015 winter wheat growing season. Soil respiration under N24 treatment was significantly higher than N0 treatment. Averaged over the two growing seasons, N12, N18 and N24 significantly increased soil respiration by 13.4, 16.4 and 25.4% compared with N0, respectively. N addition also significantly increased easily extractable glomalin-related soil protein (EEG), soil organic carbon (SOC), total N, ammonium N and nitrate N contents. In addition, soil respiration was significantly and positively correlated with β-glucosidase activity, EEG, SOC, total N, ammonium N and nitrate N contents. The results indicated that high N fertilization improved soil chemical properties, but significantly increased soil respiration. PMID:26629695

Nitrogen waste from rainbow trout (Oncorhynchus mykiss) with particular focus on urea

DEFF Research Database (Denmark)

Dalsgaard, Anne Johanne Tang; Larsen, Bodil Katrine; Pedersen, Per Bovbjerg

2015-01-01

a laboratory, mass-balance approach, the current study examined the effects of commercially applied feeding levels on the loading of different N waste forms, including daily fluctuations in dissolved total nitrogen (TN), total ammonia nitrogen (TAN), urea-N, and non-characterized, dissolved N deriving from...... juvenile rainbow trout (Oncorhynchus mykiss). In addition, the study examined whether there was a removal of urea-N across a moving bed biofilter operated as end-of-pipe under commercial conditions. The laboratory, mass-balance study showed that there were no effects of feeding levels (1.3, 1.5 or 1....../nitrogen. Results from the commercially operated, nitrifying biofilter showed that urea-N was removed at a rate of 0.014 g N m2 day−1. Compared to the removal of TAN (0.208 g N m2 day−1), the moving bed biofilter was 1.07 times more active in removing dissolved N than immediately expected when only considering TAN...

Reactions of homolytic addition of polyhalogenoalkanes to unsafurated tin-organic compounds and their application in organic synthesis

International Nuclear Information System (INIS)

Rakhlin, V.I.; Mirskov, R.G.; Voronkov, M.G.

1996-01-01

Reactions of homolytic addition of polyhalogenoalkanes; including iodine compounds, to tin trialkylalkenyl derivatives are considered. They may be used as convenient method for synthesis of various polyhalogenoalkylsubstituted alicycles and heterocycles: cyclopropane, 1.3-dioxocycloalkanes, thiacycloalkanes, various nitrogen-containing heterocycles. 27 refs

Spectroscopic study of nitrogen distribution in N-doped carbon nanotubes and nanofibers synthesized by catalytic ethylene-ammonia decomposition

Science.gov (United States)

Svintsitskiy, Dmitry A.; Kibis, Lidiya S.; Smirnov, Dmitry A.; Suboch, Arina N.; Stonkus, Olga A.; Podyacheva, Olga Yu.; Boronin, Andrei I.; Ismagilov, Zinfer R.

2018-03-01

Carbon and nitrogen species on the surface of carbon nanotubes (N-CNTs) and nanofibers (N-CNFs) were studied by X-ray absorption (XAS) and photoelectron spectroscopy (PES) including the analysis of nitrogen distribution over the depth of materials. The study was performed with a series of bamboo-like carbon nanotubes and nanofibers having the platelet-like and herringbone-like morphology. It was shown that the main nitrogen species in the composition of the studied materials are pyridine, pyrrole (and/or amino groups), graphite-like and oxidized states of nitrogen. In distinction to nanofibers, the bamboo-like nanotubes additionally contain molecular nitrogen encapsulated in the internal hollows. Spectral data for different depths of analysis were obtained by varying the energy of incident radiation. Such an approach revealed that N-CNTs are characterized by non-uniform distribution of chemically bound nitrogen species. Thus, nitrogen enrichment was observed on the external surface and in the internal arches of carbon nanotubes. Nitrogen enrichment in the subsurface region was found for N-CNFs, whereas the full depth analysis of N-distribution was limited by a large diameter of nanofibers.

Forest fuel reduces the nitrogen load - calculations of nitrogen flows

International Nuclear Information System (INIS)

Burstroem, F.; Johansson, Jan.

1995-12-01

Nitrogen deposition in Sweden has increased strongly during recent decades, particularly in southern Sweden. Nitrogen appears to be largely accumulated in biomass and in the soil. It is therefore desirable to check the accumulation of nitrogen in the forest. The most suitable way of doing this is to remove more nitrogen-rich biomass from the forest, i.e., increase the removal of felling residues from final fellings and cleanings. An ecological condition for intensive removal of fuel is that the ashes are returned. The critical load for nitrogen, CL(N), indicates the level of nitrogen deposition that the forest can withstand without leading to ecological changes. Today, nitrogen deposition is higher than the CL(N) in almost all of Sweden. CL(N) is calculated in such a manner that nitrogen deposition should largely be balanced by nitrogen losses through harvesting during a forest rotation. The value of CL(N) thus largely depends on how much nitrogen is removed with the harvested biomass. When both stems and felling residues are harvested, the CL(N) is about three times higher than in conventional forestry. The increase is directly related to the amount of nitrogen in the removed biofuel. Use of biofuel also causes a certain amount of nitrogen emissions. From the environmental viewpoint there is no difference between the sources of the nitrogen compounds. An analysis of the entire fuel chain shows that, compared with the amount of nitrogen removed from the forest with the fuel, about 5 % will be emitted as nitrogen oxides or ammonia during combustion, and a further ca 5 % during handling and transports. A net amount of about 90 % of biomass nitrogen is removed from the system and becomes inert nitrogen (N 2 ). 60 refs, 3 figs, 4 tabs, 11 appendices

Identifying organic nitrogen compounds in Rocky Mountain National Park aerosols

Science.gov (United States)

Beem, K. B.; Desyaterik, Y.; Ozel, M. Z.; Hamilton, J. F.; Collett, J. L.

2010-12-01

negative. The differences in the number of species and what species are identified between these two methods are important for planning future analyses of organic nitrogen compounds. In addition, these data provide new insight into the potential source of organic nitrogen in RMNP. Using the GCxGC method, 39 organic nitrogen species were detected and 20 were identified. Identified species include several types of amines and phenols. The LC/MS method identified several types of cresols, amines, and nitrates.

Water-bearing explosive containing nitrogen-base salt

Energy Technology Data Exchange (ETDEWEB)

Dunglinson, C.; Lyerly, W.M.

1968-10-21

A water-bearing explosive composition consists of an oxidizing salt component, a fuel component, and water. A sensitizer is included having an oxygen balance more positive than -150%, and consisting of a salt of an inorganic oxidizing acid and of an acyclic nitrogen base having no more than 2 hydrogen atoms bonded to the basic nitrogen and up to 3 carbons per basic nitrogen, and/or of a phenyl amine. 41 claims.

The Effects of Nitrogen Addition on the Uptake and Allocation of Macro- and Micronutrients in Bothriochloa ischaemum on Loess Plateau in China

Directory of Open Access Journals (Sweden)

Zemin Ai

2017-08-01

Full Text Available The effects of nitrogen (N addition on the macro- and micronutrient concentrations, storage, and allocation of Bothriochloa ischaemum (L. Keng, a native forage plant on the Loess Plateau in China remain unclear. We studied the effects of N addition at 0 (CK, 2.5 (N1, 5.0 (N2, and 10.0 (N3 g N m-2 y-1. N addition significantly decreased the available copper (Cu, zinc (Zn, and total Cu concentration, but significantly increased the available iron concentration in the soil. Cu, manganese (Mn, and sodium (Na concentrations in aboveground tissues and potassium (K, magnesium, and Zn concentrations in belowground tissues significantly increased with N addition. Calcium (Ca concentrations in belowground tissues decreased significantly. The ratios of above- to belowground Ca, Cu, Zn, and Mn significantly increased with N addition. The maximum ratios appeared at N2 for Cu, Zn, and Mn. The aboveground, belowground, and total biomass storage of studied nutrients significantly changed with N addition, and most attained maximum values under N2 treatment. The storage ratios of above- to belowground Cu, Zn, Mn, and Na attained maximum values at N2. We conclude that N addition significantly, but differentially influence the macro- and micronutrient concentrations and storage in B. ischaemum. B. ischaemum allocated and accumulated increased macro- and micronutrients to its aboveground tissues and exhibited high total storage when the amount of N addition reached 5 g N m-2 y-1.

The influence of different nitrogen and carbon sources on mycotoxin production in Alternaria alternata.

Science.gov (United States)

Brzonkalik, Katrin; Herrling, Tanja; Syldatk, Christoph; Neumann, Anke

2011-05-27

The aim of this study was to determine the influence of different carbon and nitrogen sources on the production of the mycotoxins alternariol (AOH), alternariol monomethyl ether (AME) and tenuazonic acid (TA) by Alternaria alternata at 28°C using a semi-synthetic medium (modified Czapek-Dox broth) supplemented with nitrogen and carbon sources. Additionally the effect of shaken and static cultivation on mycotoxin production was tested. Initial experiments showed a clear dependency between nitrogen depletion and mycotoxin production. To assess whether nitrogen limitation in general or the type of nitrogen source triggers the production, various nitrogen sources including several ammonium/nitrate salts and amino acids were tested. In static culture the production of AOH/AME can be enhanced greatly with phenylalanine whereas some nitrogen sources seem to inhibit the AOH/AME production completely. TA was not significantly affected by the choice of nitrogen source. In shaken culture the overall production of all mycotoxins was lower compared to static cultivation. Furthermore tests with a wide variety of carbon sources including monosaccharides, disaccharides, complex saccharides such as starch as well as glycerol and acetate were performed. In shaken culture AOH was produced when glucose, fructose, sucrose, acetate or mixtures of glucose/sucrose and glucose/acetate were used as carbon sources. AME production was not detected. The use of sodium acetate resulted in the highest AOH production. In static culture AOH production was also stimulated by acetate and the amount is comparable to shaken conditions. Under static conditions production of AOH was lower except when cultivated with acetate. In static cultivation 9 of 14 tested carbon sources induced mycotoxin production compared to 4 in shaken culture. This is the first study which analyses the influence of carbon and nitrogen sources in a semi-synthetic medium and assesses the effects of culture conditions on

Understanding Nitrogen Fixation

Energy Technology Data Exchange (ETDEWEB)

Paul J. Chirik

2012-05-25

The purpose of our program is to explore fundamental chemistry relevant to the discovery of energy efficient methods for the conversion of atmospheric nitrogen (N{sub 2}) into more value-added nitrogen-containing organic molecules. Such transformations are key for domestic energy security and the reduction of fossil fuel dependencies. With DOE support, we have synthesized families of zirconium and hafnium dinitrogen complexes with elongated and activated N-N bonds that exhibit rich N{sub 2} functionalization chemistry. Having elucidated new methods for N-H bond formation from dihydrogen, C-H bonds and Broensted acids, we have since turned our attention to N-C bond construction. These reactions are particularly important for the synthesis of amines, heterocycles and hydrazines with a range of applications in the fine and commodity chemicals industries and as fuels. One recent highlight was the discovery of a new N{sub 2} cleavage reaction upon addition of carbon monoxide which resulted in the synthesis of an important fertilizer, oxamide, from the diatomics with the two strongest bonds in chemistry. Nitrogen-carbon bonds form the backbone of many important organic molecules, especially those used in the fertilizer and pharamaceutical industries. During the past year, we have continued our work in the synthesis of hydrazines of various substitution patterns, many of which are important precursors for heterocycles. In most instances, the direct functionalization of N{sub 2} offers a more efficient synthetic route than traditional organic methods. In addition, we have also discovered a unique CO-induced N{sub 2} bond cleavage reaction that simultaneously cleaves the N-N bond of the metal dinitrogen compound and assembles new C-C bond and two new N-C bonds. Treatment of the CO-functionalized core with weak Broensted acids liberated oxamide, H{sub 2}NC(O)C(O)NH{sub 2}, an important slow release fertilizer that is of interest to replace urea in many applications. The

The nitrogen cycle on Mars

Science.gov (United States)

Mancinelli, Rocco L.

1989-01-01

Nirtogen is an essential element for the evolution of life, because it is found in a variety of biologically important molecules. Therefore, N is an important element to study from a exobiological perspective. In particular, fixed nitrogen is the biologically useful form of nitrogen. Fixed nitrogen is generally defines as NH3, NH4(+), NO(x), or N that is chemically bound to either inorganic or organic molecules, and releasable by hydrolysis to NH3 or NH4(+). On Earth, the vast majority of nitrogen exists as N2 in the atmosphere, and not in the fixes form. On early Mars the same situations probably existed. The partial pressure of N2 on early Mars was thought to be 18 mb, significantly less than that of Earth. Dinitrogen can be fixed abiotically by several mechanisms. These mechanisms include thernal shock from meteoritic infall and lightning, as well as the interaction of light and sand containing TiO2 which produces NH3 that would be rapidly destroyed by photolysis and reaction with OH radicals. These mechanisms could have been operative on primitive Mars.The chemical processes effecting these compounds and possible ways of fixing or burying N in the Martian environment are described. Data gathered in this laboratory suggest that the low abundance of nitrogen along (compared to primitive Earth) may not significantly deter the origin and early evolution of a nitrogen utilizing organisms. However, the conditions on current Mars with respect to nitrogen are quite different, and organisms may not be able to utilize all of the available nitrogen.

Contribution of bacterial cell nitrogen to soil humic fractions

International Nuclear Information System (INIS)

Knowles, R.; Barro, L.

1981-01-01

Living cells of Serratia marcescens, uniformly labelled with 15 N, were added to samples of maple (Acer saccharum) and black spruce (Picea mariana) forest soils. After different periods of incubation from zero time to 100 days, the soils were subjected to alkali-acid and phenol extraction to provide humic acid, fulvic acid, humin and 'humoprotein' fractions. Significant amounts of the cell nitrogen were recovered in the humic and fulvic acids immediately after addition. After incubation, less cell nitrogen appeared in the humic acid and more in the fulvic acid. The amount of cell nitrogen recovered in the humin fraction increased with incubation. Roughly 5 to 10 per cent of the added cell nitrogen was found as amino acid nitrogen from humoprotein in a phenol extract of the humic acid. The data are consistent with the occurrence of co-precipitation of biologically labile biomass nitrogen compounds with humic polymers during the alkaline extraction procedure involved in the humic-fulvic fractionation. (orig.)

Nitrogen balance of healthy Dutch women before and during pregnancy

NARCIS (Netherlands)

Mojtahedi, M.; Groot, de C.P.G.M.; Boekholt, H.A.; Raaij, van J.M.A.

2002-01-01

Background: Experimental studies including longitudinal nitrogen balance studies could provide insight into protein metabolism in pregnancy. Objective: Our aim was to determine the development of nitrogen balance during pregnancy compared with nitrogen balance before pregnancy in women consuming

A tradeoff frontier for global nitrogen use and cereal production

International Nuclear Information System (INIS)

Mueller, Nathaniel D; West, Paul C; Gerber, James S; MacDonald, Graham K; Foley, Jonathan A; Polasky, Stephen

2014-01-01

Nitrogen fertilizer use across the world’s croplands enables high-yielding agricultural production, but does so at considerable environmental cost. Imbalances between nitrogen applied and nitrogen used by crops contributes to excess nitrogen in the environment, with negative consequences for water quality, air quality, and climate change. Here we utilize crop input-yield models to investigate how to minimize nitrogen application while achieving crop production targets. We construct a tradeoff frontier that estimates the minimum nitrogen fertilizer needed to produce a range of maize, wheat, and rice production levels. Additionally, we explore potential environmental consequences by calculating excess nitrogen along the frontier using a soil surface nitrogen balance model. We find considerable opportunity to achieve greater production and decrease both nitrogen application and post-harvest excess nitrogen. Our results suggest that current (circa 2000) levels of cereal production could be achieved with ∼50% less nitrogen application and ∼60% less excess nitrogen. If current global nitrogen application were held constant but spatially redistributed, production could increase ∼30%. If current excess nitrogen were held constant, production could increase ∼40%. Efficient spatial patterns of nitrogen use on the frontier involve substantial reductions in many high-use areas and moderate increases in many low-use areas. Such changes may be difficult to achieve in practice due to infrastructure, economic, or political constraints. Increases in agronomic efficiency would expand the frontier to allow greater production and environmental gains

Clinoptilolite zeolite influence on inorganic nitrogen in silt loam and sandy agricultural soils

Science.gov (United States)

Development of best management practices can help improve inorganic nitrogen (N) availability to plants and reduce nitrate-nitrogen (NO3-N) leaching in soils. This study was conducted to determine the influence of the zeolite mineral Clinoptilolite (CL) additions on NO3-N and ammonium-nitrogen (NH4...

Chronic nitrogen deposition influences the chemical dynamics ...

Science.gov (United States)

Atmospheric nitrogen deposition induces a forest carbon sink across broad parts of the Northern Hemisphere; this carbon sink may partly result from slower litter decomposition. Although microbial responses to experimental nitrogen deposition have been well-studied, evidence linking these microbial responses to changes in the degradation of specific compounds in decaying litter is sparse. We used wet chemistry and Fourier transform infrared spectroscopy (FTIR) methodologies to study the effects of chronic simulated nitrogen deposition on leaf litter and fine root chemistry during a three-year decomposition experiment at four northern hardwood forests in the north-central USA. Leaf litter and fine roots were highly different in initial chemistry such as concentrations of acid-insoluble fraction (AIF, or Klason lignin) and condensed tannins (CTs). These initial differences persisted over the course of decomposition. Results from gravimetrically-defined AIF and lignin/carbohydrate reference IR peak ratios both provide evidence that lignin in fine roots was selectively preserved under simulated nitrogen deposition. Lignin/carbohydrate peak ratios were strongly correlated with AIF, suggesting that AIF is a good predictor of lignin. Because AIF is abundant in fine roots, slower AIF degradation was the major driver of the slower fine root decomposition under nitrogen enrichment, explaining 73.9 % of the additional root mass retention. Nitrogen enrichment also slowed the

Microbial nitrogen cycling in Arctic snowpacks

International Nuclear Information System (INIS)

Larose, Catherine; Vogel, Timothy M; Dommergue, Aurélien

2013-01-01

Arctic snowpacks are often considered as chemical reactors for a variety of chemicals deposited through wet and dry events, but are overlooked as potential sites for microbial metabolism of reactive nitrogen species. The fate of deposited species is critical since warming leads to the transfer of contaminants to snowmelt-fed ecosystems. Here, we examined the role of microorganisms and the potential pathways involved in nitrogen cycling in the snow. Next generation sequencing data were used to follow functional gene abundances and a 16S rRNA (ribosomal ribonucleic acid) gene microarray was used to follow shifts in microbial community structure during a two-month spring-time field study at a high Arctic site, Svalbard, Norway (79° N). We showed that despite the low temperatures and limited water supply, microbial communities inhabiting the snow cover demonstrated dynamic shifts in their functional potential to follow several different pathways of the nitrogen cycle. In addition, microbial specific phylogenetic probes tracked different nitrogen species over time. For example, probes for Roseomonas tracked nitrate concentrations closely and probes for Caulobacter tracked ammonium concentrations after a delay of one week. Nitrogen cycling was also shown to be a dominant process at the base of the snowpack. (letter)

Nitrogen enriched combustion of a natural gas internal combustion engine to reduce NO.sub.x emissions

Science.gov (United States)

Biruduganti, Munidhar S.; Gupta, Sreenath Borra; Sekar, R. Raj; McConnell, Steven S.

2008-11-25

A method and system for reducing nitrous oxide emissions from an internal combustion engine. An input gas stream of natural gas includes a nitrogen gas enrichment which reduces nitrous oxide emissions. In addition ignition timing for gas combustion is advanced to improve FCE while maintaining lower nitrous oxide emissions.

Responses of Ammonia-Oxidising Bacterial Communities to Nitrogen, Lime, and Plant Species in Upland Grassland Soil

International Nuclear Information System (INIS)

Rooney, D.C.; Kennedy, N.M.; Clipson, N.J.W.; Rooney, D.C.; Kennedy, N.M.; Gleeson, D.B.

2010-01-01

Agricultural improvement of semi natural grasslands has been shown to result in changes to plant and microbial diversity, with consequences for ecosystem functioning. A microcosm approach was used to elucidate the effects of two key components of agricultural improvement (nitrogen addition and liming) on ammonia-oxidising bacterial (AOB) communities in an upland grassland soil. Plant species characteristic of unimproved and improved pastures (A. capillaries and L. perenne) were planted in microcosms, and lime, nitrogen (NH 4 NO 3 ), or lime plus nitrogen added. The AOB community was profiled using terminal restriction fragment length polymorphism (TRFLP) of the amoA gene. AOB community structure was largely altered by NH 4 NO 3 addition, rather than liming, although interactions between nitrogen addition and plant species were also evident. Results indicate that nitrogen addition drives shifts in the structure of key microbial communities in upland grassland soils, and that plant species may play a significant role in determining AOB community structure

Increased rainfall variability and N addition accelerate litter decomposition in a restored prairie.

Science.gov (United States)

Schuster, Michael J

2016-03-01

Anthropogenic nitrogen deposition and projected increases in rainfall variability (the frequency of drought and heavy rainfall events) are expected to strongly influence ecosystem processes such as litter decomposition. However, how these two global change factors interact to influence litter decomposition is largely unknown. I examined how increased rainfall variability and nitrogen addition affected mass and nitrogen loss of litter from two tallgrass prairie species, Schizachyrium scoparium and Solidago canadensis, and isolated the effects of each during plant growth and during litter decomposition. I increased rainfall variability by consolidating ambient rainfall into larger events and simulated chronic nitrogen deposition using a slow-release urea fertilizer. S. scoparium litter decay was more strongly regulated by the treatments applied during plant growth than by those applied during decomposition. During plant growth, increased rainfall variability resulted in S. scoparium litter that subsequently decomposed more slowly and immobilized more nitrogen than litter grown under ambient conditions, whereas nitrogen addition during plant growth accelerated subsequent mass loss of S. scoparium litter. In contrast, S. canadensis litter mass and N losses were enhanced under either N addition or increased rainfall variability both during plant growth and during decomposition. These results suggest that ongoing changes in rainfall variability and nitrogen availability are accelerating nutrient cycling in tallgrass prairies through their combined effects on litter quality, environmental conditions, and plant community composition.

Atomic state and characterization of nitrogen at the SiC/SiO2 interface

International Nuclear Information System (INIS)

Xu, Y.; Garfunkel, E. L.; Zhu, X.; Lee, H. D.; Xu, C.; Shubeita, S. M.; Gustafsson, T.; Ahyi, A. C.; Sharma, Y.; Williams, J. R.; Lu, W.; Ceesay, S.; Tuttle, B. R.; Pantelides, S. T.; Wan, A.; Feldman, L. C.

2014-01-01

We report on the concentration, chemical bonding, and etching behavior of N at the SiC(0001)/SiO 2 interface using photoemission, ion scattering, and computational modeling. For standard NO processing of a SiC MOSFET, a sub-monolayer of nitrogen is found in a thin inter-layer between the substrate and the gate oxide (SiO 2 ). Photoemission shows one main nitrogen related core-level peak with two broad, higher energy satellites. Comparison to theory indicates that the main peak is assigned to nitrogen bound with three silicon neighbors, with second nearest neighbors including carbon, nitrogen, and oxygen atoms. Surprisingly, N remains at the surface after the oxide was completely etched by a buffered HF solution. This is in striking contrast to the behavior of Si(100) undergoing the same etching process. We conclude that N is bound directly to the substrate SiC, or incorporated within the first layers of SiC, as opposed to bonding within the oxide network. These observations provide insights into the chemistry and function of N as an interface passivating additive in SiC MOSFETs

Exogenous nutrients and carbon resource change the responses of soil organic matter decomposition and nitrogen immobilization to nitrogen deposition

Science.gov (United States)

He, Ping; Wan, Song-Ze; Fang, Xiang-Min; Wang, Fang-Chao; Chen, Fu-Sheng

2016-01-01

It is unclear whether exogenous nutrients and carbon (C) additions alter substrate immobilization to deposited nitrogen (N) during decomposition. In this study, we used laboratory microcosm experiments and 15N isotope tracer techniques with five different treatments including N addition, N+non-N nutrients addition, N+C addition, N+non-N nutrients+C addition and control, to investigate the coupling effects of non-N nutrients, C addition and N deposition on forest floor decomposition in subtropical China. The results indicated that N deposition inhibited soil organic matter and litter decomposition by 66% and 38%, respectively. Soil immobilized 15N following N addition was lowest among treatments. Litter 15N immobilized following N addition was significantly higher and lower than that of combined treatments during the early and late decomposition stage, respectively. Both soil and litter extractable mineral N were lower in combined treatments than in N addition treatment. Since soil N immobilization and litter N release were respectively enhanced and inhibited with elevated non-N nutrient and C resources, it can be speculated that the N leaching due to N deposition decreases with increasing nutrient and C resources. This study should advance our understanding of how forests responds the elevated N deposition. PMID:27020048

Control of nitrogen concentration in liquid lithium by hot trapping

International Nuclear Information System (INIS)

Sakurai, Toshiharu; Yoneoka, Toshiaki; Tanaka, Satoru; Suzuki, Akihiro; Muroga, Takeo

2002-01-01

Nitrogen concentration in liquid lithium was controlled by the method of hot trapping. V-Ti alloy and chromium were used as nitrogen gettering materials. Chromium is known to form ternary nitride with lithium. Gettering experiments were conducted at 823 K for 0.8-2.2 Ms. Under high nitrogen concentration in liquid lithium, above 10 -2 mass%, nitrogen gettering effect of chromium was found to be larger than that of V-10at.% Ti alloy. Nitrogen gettering by chromium at 823 K reached a limit at about 6.5x10 -3 mass% of nitrogen concentration in liquid lithium. Instability of ternary nitride of chromium and lithium below this nitrogen concentration in liquid lithium was considered to be the reason for this limit. The composition of the ternary nitride that was formed in this study was considered to be Li 6 Cr(III) 3 N 5 . In addition, immersion experiments of yttrium with V-10at.% Ti alloy were performed. It was found that nitriding of yttrium in liquid lithium is controlled by nitrogen gettering effect of V-10at.% Ti alloy

Nitrogen Oxide Emission, Economic Growth and Urbanization in China: a Spatial Econometric Analysis

Science.gov (United States)

Zhou, Zhimin; Zhou, Yanli; Ge, Xiangyu

2018-01-01

This research studies the nexus of nitrogen oxide emissions and economic development/urbanization. Under the environmental Kuznets curve (EKC) hypothesis, we apply the analysis technique of spatial panel data in the STIRPAT framework, and thus obtain the estimated impacts of income/urbanization on nitrogen oxide emission systematically. The empirical findings suggest that spatial dependence on nitrogen oxide emission distribution exist at provincial level, and the inverse N-shape EKC describes both income-nitrogen oxide and urbanization-nitrogen oxide nexuses. In addition, some well-directed policy advices are made to reduce the nitrogen oxide emission in future.

Long-term N and P additions alter the scaling of plant nitrogen to phosphorus in a Tibetan alpine meadow.

Science.gov (United States)

Zhang, Juanjuan; Yan, Xuebin; Su, Fanglong; Li, Zhen; Wang, Ying; Wei, Yanan; Ji, Yangguang; Yang, Yi; Zhou, Xianhui; Guo, Hui; Hu, Shuijin

2018-06-01

Nitrogen and phosphorus are two important nutrient elements for plants. The current paradigm suggests that the scaling of plant tissue N to P is conserved across environments and plant taxa because these two elements are coupled and coordinately change with each other following a constant allometric trajectory. However, this assumption has not been vigorously examined, particularly in changing N and P environments. We propose that changes in relative availability of N and P in soil alter the N to P relationship in plants. Taking advantage of a 4-yr N and P addition experiment in a Tibetan alpine meadow, we examined changes in plant N and P concentrations of 14 common species. Our results showed that while the scaling of N to P under N additions was similar to the previously reported pattern with a uniform 2/3 slope of the regression between log N and log P, it was significantly different under P additions with a smaller slope. Also, graminoids had different responses from forbs. These results indicate that the relative availability of soil N and P is an important determinant regulating the N and P concentrations in plants. These findings suggest that alterations in the N to P relationships may not only alter plant photosynthate allocation to vegetative or reproductive organs, but also regulate the metabolic and growth rate of plant and promote shifts in plant community composition in a changing nutrient loading environment. Copyright © 2017 Elsevier B.V. All rights reserved.

Effect of irrigation disruption and biological nitrogen on growth and ...

African Journals Online (AJOL)

In addition, the maximum (4.29 %) harvest index was obtained from irrigation disruption at third and second harvest with 9 L/ha of nitroxin application. In conclusion, lower amounts of nitrogen was needed to produced the optimal yield of seed in water deficit situation compared with non stress condition, while the nitrogen ...

Nitrogen availability for nitrogen fixing cyanobacteria upon growth ...

African Journals Online (AJOL)

The filamentous cyanobacterium Nostoc PCC 7120 is able to convert dinitrogen to ammonia in the absence of combined nitrogen. The expression of 20% of coding sequences from all major metabolic categories was examined in nitrogen fixing and non-nitrogen fixing growth conditions. The expression data were correlated ...

Effects of Watering and Nitrogen Fertilization on Yield and Water and Nitrogen Use Efficiency of Cropping Oil Sunflower

Directory of Open Access Journals (Sweden)

TAN Jian-xin

2015-10-01

Full Text Available The field experiment with split-plot design was conducted to study the effects of the interaction of water and nitrogen fertilization on the growth and yield of oil sunflower, water and nitrogen use efficiency of cropping oil sunflower. This experiment set three irrigation rate treatments, including high irrigation treatment (5 250 m3·hm-2, middle irrigation treatment (3 750 m3·hm-2, low irrigation treatment (2 250 m3·hm-2, and four nitrogen application rate treatments, covering no nitrogen fertilization treatment (0 kg·hm-2, low nitrogen application treatment (120 kg·hm-2, middle nitrogen application treatment (240 kg·hm-2 and high nitrogen application treatment (360 kg·hm-2. The results showed that the nitrogen absorption and nitrogen use efficiency of cropping oil sunflower increased as the irrigation rate increased. With the nitrogen application rate increased, the yield of cropping oil sunflower was increased when the nitrogen application rate was 0~240 kg·hm-2, but beyond the 240 kg·hm-2, there was no significant increase. With the irrigation rate increased, the water consumption amount of cropping oil sunflower increased all the time, but the water use efficiency increased first, and hen decreased. Besides there was no significant difference between 240 kg·hm-2 and 360 kg·hm-2 treatment. Under our experiment condition, during the cropping oil sunflower growth period, when the irrigation rate was 5 250 m3·hm-2 (high irrigation rate and the nitrogen ertilization was 360 m3·hm-2 (high nitrogen application rate, the yield of cropping oil sunflower was 3 598 kg·hm-2. When the irrigation rate was 3 750 m3·hm-2 (middle irrigation rate and the nitrogen fertilization was 240 m3·hm-2 (middle nitrogen application rate, the yield was 3 518 kg·hm-2, with the yield components similar with the high irrigation rate and high nitrogen application rate treatment. Considering various factors, middle irrigation rate and middle nitrogen

Mineral commodity profiles: nitrogen

Science.gov (United States)

Kramer, Deborah A.

2004-01-01

Overview -- Nitrogen (N) is an essential element of life and a part of all animal and plant proteins. As a part of the DNA and RNA molecules, nitrogen is an essential constituent of each individual's genetic blueprint. As an essential element in the chlorophyll molecule, nitrogen is vital to a plant's ability to photosynthesize. Some crop plants, such as alfalfa, peas, peanuts, and soybeans, can convert atmospheric nitrogen into a usable form by a process referred to as 'fixation.' Most of the nitrogen that is available for crop production, however, comes from decomposing animal and plant waste or from commercially produced fertilizers. Commercial fertilizers contain nitrogen in the form of ammonium and/or nitrate or in a form that is quickly converted to the ammonium or nitrate form once the fertilizer is applied to the soil. Ammonia is generally the source of nitrogen in fertilizers. Anhydrous ammonia is commercially produced by reacting nitrogen with hydrogen under high temperatures and pressures. The source of nitrogen is the atmosphere, which is almost 80 percent nitrogen. Hydrogen is derived from a variety of raw materials, which include water, and crude oil, coal, and natural gas hydrocarbons. Nitrogen-based fertilizers are produced from ammonia feedstocks through a variety of chemical processes. Small quantities of nitrates are produced from mineral resources principally in Chile. In 2002, anhydrous ammonia and other nitrogen materials were produced in more than 70 countries. Global ammonia production was 108 million metric tons (Mt) of contained nitrogen. With 28 percent of this total, China was the largest producer of ammonia. Asia contributed 46 percent of total world ammonia production, and countries of the former U.S.S.R. represented 13 percent. North America also produced 13 percent of the total; Western Europe, 9 percent; the Middle East, 7 percent; Central America and South America, 5 percent; Eastern Europe, 3 percent; and Africa and Oceania

Organic amendment of crop soil and its relation to hotspots of bacterial nitrogen cycling

Science.gov (United States)

Pereg, Lily; McMillan, Mary

2015-04-01

Crop production in Australian soils requires a high use of fertilisers, including N, P and K for continues utilisation of the soil. Growers often grow crops in rotation of summer crop, such as cotton with winter crop, such as wheat in the same field. Growers are getting more and more aware about sustainability of the soil resources and the more adventurous ones use soil amendments, such as organic supplements in addition to the chemical fertilisers. We have collected soil samples from fields that were cultivated in preparation for planting cotton and tested the soil for its bacterial populations with potential to perform different functions, including those related to the nitrogen cycling. One of our aims was to determine whether organic amendments create hotspots for bacterial functions related to bacterial nitrogen cycling. This pan of the project will be discussed in this presentation.

Modeling nitrogen fluxes in Germany - where does the nitrogen go?

Science.gov (United States)

Klement, Laura; Bach, Martin; Breuer, Lutz

2016-04-01

According to the latest inventory of the EU Water Framework Directive, 26.3% of German groundwater bodies are in a poor chemical state regarding nitrate. Additionally, the EU initiated infringement proceedings against Germany for not meeting the quality standards of the EU Nitrate Directive. Agriculture has been determined as the main source of nitrate pollution due to over-fertilization and regionally high density of livestock farming. The nitrogen balance surplus is commonly used as an indicator characterizing the potential of nitrate leaching into groundwater bodies and thus also serves as a foundation to introduce legislative restrictions or to monitor the success of mitigation measures. Currently, there is an ongoing discussion which measures are suitable for reducing the risk of nitrate leaching and also to what extent. However, there is still uncertainty about just how much the nitrogen surplus has to be reduced to meet the groundwater quality standards nationwide. Therefore, the aims of our study were firstly to determine the level of the nitrogen surplus that would be acceptable at the utmost and secondly whether the currently discussed target value of 30 kg N per hectare agricultural land for the soil surface nitrogen balance would be sufficient. The models MONERIS (Modeling Nutrient Emissions in River System) and MoRE (Modelling of Regionalized Emissions), the latter based on the first, are commonly used for estimating nitrogen loads into the river system in Germany at the mesoscale, as well as the effect of mitigation measures in the context of the EU directive 2008/105/EC (Environmental quality standards applicable to surface water). We used MoRE to calculate nitrate concentration for 2759 analytical units in Germany. Main factors are the surplus of the soil surface nitrogen balance, the percolation rate and an exponent representing the denitrification in the vadose zone. The modeled groundwater nitrate concentrations did not correspond to the regional

The Effect of Nitrogen Enrichment on C1-Cycling Microorganisms and Methane Flux in Salt Marsh Sediments

Directory of Open Access Journals (Sweden)

Irina Catherine Irvine

2012-03-01

Full Text Available Methane (CH4 flux from ecosystems is driven by C1-cycling microorganisms – the methanogens and the methylotrophs. Little is understood about what regulates these communities, complicating predictions about how global change drivers such as nitrogen enrichment will affect methane cycling. Using a nitrogen addition gradient experiment in three Southern California salt marshes, we show that sediment CH4 flux increased linearly with increasing nitrogen addition (1.23 µg CH4 m-2 d-1 for each g N m-2 yr-1 applied after seven months of fertilization. To test the reason behind this increased CH4 flux, we conducted a microcosm experiment altering both nitrogen and carbon availability under aerobic and anaerobic conditions. Methanogenesis appeared to be both nitrogen and carbon (acetate limited. N and C each increased methanogenesis by 18%, and together by 44%. In contrast, methanotrophy was stimulated by carbon (methane addition (830%, but was unchanged by nitrogen addition. Sequence analysis of the sediment methylotroph community with the methanol dehydrogenase gene (mxaF revealed three distinct clades that fall outside of known lineages. However, in agreement with the microcosm results, methylotroph abundance (assayed by qPCR and composition (assayed by T-RFLP did not vary across the experimental nitrogen gradient in the field. Together, these results suggest that nitrogen enrichment to salt marsh sediments increases methane flux by stimulating the methanogen community.

Experimental identification of nitrogen-vacancy complexes in nitrogen implanted silicon

Science.gov (United States)

Adam, Lahir Shaik; Law, Mark E.; Szpala, Stanislaw; Simpson, P. J.; Lawther, Derek; Dokumaci, Omer; Hegde, Suri

2001-07-01

Nitrogen implantation is commonly used in multigate oxide thickness processing for mixed signal complementary metal-oxide-semiconductor and System on a Chip technologies. Current experiments and diffusion models indicate that upon annealing, implanted nitrogen diffuses towards the surface. The mechanism proposed for nitrogen diffusion is the formation of nitrogen-vacancy complexes in silicon, as indicated by ab initio studies by J. S. Nelson, P. A. Schultz, and A. F. Wright [Appl. Phys. Lett. 73, 247 (1998)]. However, to date, there does not exist any experimental evidence of nitrogen-vacancy formation in silicon. This letter provides experimental evidence through positron annihilation spectroscopy that nitrogen-vacancy complexes indeed form in nitrogen implanted silicon, and compares the experimental results to the ab initio studies, providing qualitative support for the same.

Nitrogen fixation by free-living microorganisms in tropical rice soils using labelled fertilizer. Part of a coordinated programme on isotope techniques in studies of biological nitrogen fixation for the dual purpose of increasing crop production and decreasing nitrogen fertilizer use to conserve the environment

International Nuclear Information System (INIS)

Rao, V.R.

1981-11-01

Both acetylene-reduction and 15 N techniques were used to study heterotrophic N fixation in the rhizosphere of rice plants. Soils subjected to flooding in 4 soil types in both greenhouse and the field were found to stimulate greater heterotrophic nitrogen fixation than moist soils. The addition of organic materials, in particular, cellulose and rice straw, in general, enhanced nitrogen fixed by heterotrophic organisms living in the rhizosphere of rice plants. The highest amount of N fixed was 38 kg N/ha, and was obtained in a flooded lateritic soil to which had been added cellulose. Heterotrophic nitrogen fixation was influenced by soil type. In this study, the lowest value for fixed N was recorded in an acid sulphate soil of low pH. The addition of increasing amounts of inorganic nitrogen fertilizer in the form of ammonium sulphate suppressed rhizospheric nitrogen fixation in all soils, but the extent of suppression differed in the different soils. Benomyl fungicide and methyl carbamate insecticide had a stimulatory effect on heterotrophic nitrogen fixation in soils under rice roots. Different rice cultivars stimulated strains of Azospirillum to varying extent, and thus did not fix nitrogen to the same extent. It is thus possible that varieties of rice could be selected on the basis of their ability to support non-symbiotic N fixation in their rhizosphere

Transgenic plants that exhibit enhanced nitrogen assimilation

Science.gov (United States)

Coruzzi, Gloria M.; Brears, Timothy

1999-01-01

The present invention relates to a method for producing plants with improved agronomic and nutritional traits. Such traits include enhanced nitrogen assimilatory and utilization capacities, faster and more vigorous growth, greater vegetative and reproductive yields, and enriched or altered nitrogen content in vegetative and reproductive parts. More particularly, the invention relates to the engineering of plants modified to have altered expression of key enzymes in the nitrogen assimilation and utilization pathways. In one embodiment of the present invention, the desired altered expression is accomplished by engineering the plant for ectopic overexpression of one of more the native or modified nitrogen assimilatory enzymes. The invention also has a number of other embodiments, all of which are disclosed herein.

Nitrogen nutrition effects on development, growth and nitrogen accumulation of vegetables

NARCIS (Netherlands)

Biemond, H.

1995-01-01

In order to be able to match nitrogen supply and nitrogen requirement of vegetable crops, insight is necessary in the responses to nitrogen of important processes of growth and development. This study focused on effects of amount of nitrogen applied and fractionation of nitrogen supply on

Phosphorus and nitrogen in the eutrophication of waters

International Nuclear Information System (INIS)

Salonen, S.; Frisk, T.; Kaermeniemi, T.; Niemi, J.; Pitkaenen, H.; Silvo, K.; Vuoristo, H.

1992-01-01

This report is a summary of the contribution of nitrogen and phosphorus in the eutrophication process of inland and coastal waters. Special attention was paid to the mechanisms of these nutrients in regulating biological processes and to the methods available in estimating their effects in the eutrophication of water bodies. The report includes five chapters which are entitled: Introduction, which is a general background to the subject with special attention to the requirements of the Finnish Water Act. Phosphorus and nitrogen as factors regulating biological processes. The topics included are: definition of eutrophication, forms of phosphorus and nitrogen and their sources to inland and coastal waters, effects of these nutrients as growth factors of phytoplankton and macrophytes and consequences of eutrophication. Estimation of the effects of phosphorus and nitrogen. The topics discussed from the point of view of the tasks of the National Board of Waters and the Environment are: estimation of the effects of phosphorus and nitrogen in the planning and supervision of industry, fish farming, peat production, municipalities, agriculture and forestry. A brief state-of-the art of the research carried out in the National Board of Waters and the Environment is given. Methods of estimating the effects of phosphorus and nitrogen loading in waters. The topics are: relationships between phosphorus and nitrogen concentrations in waters, material balances, water quality models, classification of waters and different groups of organisms as indicators of water quality. Conclusions for the estimation of the effects of phosphorus and nitrogen in receiving waters

In Situ One-Step Synthesis of Hierarchical Nitrogen-Doped Porous Carbon for High Performance Supercapacitors

Energy Technology Data Exchange (ETDEWEB)

Jeon, Ju Won [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Texas A & M Univ., College Station, TX (United States); Sharma, Ronish [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Meduri, Praveen [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Arey, Bruce W. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Schaef, Herbert T. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Lutkenhaus, Jodie [Texas A & M Univ., College Station, TX (United States); Lemmon, John P. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Thallapally, Praveen K. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Nandasiri, Manjula I. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); McGrail, B. Peter [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Nune, Satish K. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States)

2014-04-30

Electrochemical performance of the existing state-of-the art capacitors is not very high, key scientific barrier is that its charge storage mechanism wholly depends on adsorption of electrolyte on electrode. We present a novel method for the synthesis of nitrogen -doped porous carbons and address the drawback by precisely controlling composition and surface area. Nitrogen-doped porous carbon was synthesized using a self-sacrificial template technique without any additional nitrogen and carbon sources. They exhibited exceptionally high capacitance (239 Fg-1) due to additional pseudocapacitance originating from doped nitrogen. Cycling tests showed no obvious capacitance decay even after 10,000 cycles, which meets the requirement of commercial supercapacitors. Our method is simple and highly efficient for the production of large quantities of nitrogen-doped porous carbons.

The Global Nitrogen Cycle

Science.gov (United States)

Galloway, J. N.

2003-12-01

Once upon a time nitrogen did not exist. Today it does. In the intervening time the universe was formed, nitrogen was created, the Earth came into existence, and its atmosphere and oceans were formed! In this analysis of the Earth's nitrogen cycle, I start with an overview of these important events relative to nitrogen and then move on to the more traditional analysis of the nitrogen cycle itself and the role of humans in its alteration.The universe is ˜15 Gyr old. Even after its formation, there was still a period when nitrogen did not exist. It took ˜300 thousand years after the big bang for the Universe to cool enough to create atoms; hydrogen and helium formed first. Nitrogen was formed in the stars through the process of nucleosynthesis. When a star's helium mass becomes great enough to reach the necessary pressure and temperature, helium begins to fuse into still heavier elements, including nitrogen.Approximately 10 Gyr elapsed before Earth was formed (˜4.5 Ga (billion years ago)) by the accumulation of pre-assembled materials in a multistage process. Assuming that N2 was the predominate nitrogen species in these materials and given that the temperature of space is -270 °C, N2 was probably a solid when the Earth was formed since its boiling point (b.p.) and melting point (m.p.) are -196 °C and -210 °C, respectively. Towards the end of the accumulation period, temperatures were probably high enough for significant melting of some of the accumulated material. The volcanic gases emitted by the resulting volcanism strongly influenced the surface environment. Nitrogen was converted from a solid to a gas and emitted as N2. Carbon and sulfur were probably emitted as CO and H2S (Holland, 1984). N2 is still the most common nitrogen volcanic gas emitted today at a rate of ˜2 TgN yr-1 (Jaffee, 1992).Once emitted, the gases either remained in the atmosphere or were deposited to the Earth's surface, thus continuing the process of biogeochemical cycling. The rate of

Effect of Plant Density, Rate and Split Application of Nitrogen Fertilizer on Quality Characteristics and Nitrogen Use Efficiency of Safflower under Weed Competition

Directory of Open Access Journals (Sweden)

M Fuladvand

2015-09-01

Full Text Available In order to evaluation of plant density, rate and method of nitrogen fertilizer split application on quality characteristics and nitrogen use efficiency of safflower (Sofeh variety under weed competition a field experiment was carried out in field research Yasouj University in 2013. This experiment was a factorial based on randomized complete block design with three replications. First factor was a two levels plant density (20 and 40 plants m-2 and second factor was nitrogen rate application on nine levels. That included; non nitrogen application and 75 and 150 kgN ha-1 nitrogen application that both used with four split method. Split methods were included; S1 (%50 in pre planting stage - %50 in stem elongation stage, S2 (%25 in pre planting stage - %75 in stem elongation stage, S3 (%25 in pre planting stage - %50 in stem elongation stage -%25 in flowering stage and S4 (%25 in pre planting stage - %25 in stem elongation stage - %25 in flowering stage. Also in this experiment, weed did not control. Results showed that whit increasing crop density, oil yield and protein grain yield increased by 20 percent and nitrogen utilization efficiency increased by 10 percent. The highest oil yield (50.25 g m-2 was obtained from 75 kg ha-1 nitrogen with three-stage split application (S4. Finally, results showed that increasing nitrogen fertilizer application decreased nitrogen utilization efficiency but three-stage split method application increased this trait.

Respiration and nitrogen assimilation: targeting mitochondria-associated metabolism as a means to enhance nitrogen use efficiency.

Science.gov (United States)

Foyer, Christine H; Noctor, Graham; Hodges, Michael

2011-02-01

Considerable advances in our understanding of the control of mitochondrial metabolism and its interactions with nitrogen metabolism and associated carbon/nitrogen interactions have occurred in recent years, particularly highlighting important roles in cellular redox homeostasis. The tricarboxylic acid (TCA) cycle is a central metabolic hub for the interacting pathways of respiration, nitrogen assimilation, and photorespiration, with components that show considerable flexibility in relation to adaptations to the different functions of mitochondria in photosynthetic and non-photosynthetic cells. By comparison, the operation of the oxidative pentose phosphate pathway appears to represent a significant limitation to nitrogen assimilation in non-photosynthetic tissues. Valuable new insights have been gained concerning the roles of the different enzymes involved in the production of 2-oxoglutarate (2-OG) for ammonia assimilation, yielding an improved understanding of the crucial role of cellular energy balance as a broker of co-ordinate regulation. Taken together with new information on the mechanisms that co-ordinate the expression of genes involved in organellar functions, including energy metabolism, and the potential for exploiting the existing flexibility for NAD(P)H utilization in the respiratory electron transport chain to drive nitrogen assimilation, the evidence that mitochondrial metabolism and machinery are potential novel targets for the enhancement of nitrogen use efficiency (NUE) is explored.

A study on radiolytic nitrogen compounds in bwr primary systems

International Nuclear Information System (INIS)

Ibe, Eishi; Karasawa, Hidetoshi; Endo, Masao; Suzuki, Kazumichi; Etho, Yoshinori

1988-01-01

Behavior of nitrogen compounds in a γ radiation field was evaluated. Twenty-four species and 73 reactions were proposed for analysis of the system. It was pointed out that reactions dominating analysis reliability were primary reactions which lead to evolution of atomic nitrogen and reactions related to ammonium ion decomposition. Theoretical calculations for the BWR primary system revealed that: (i) in-leaked nitrogen from a condenser did not deteriorate the oxygen reduction efficiency due to hydrogen addition in reactor water; (ii) most 16 N atmos released in the main steam line were in the form of nitrogen mono-oxide under both hydrogen and normal water chemistry; (iii) 16 N atoms in nitric and nitrous acids under normal water chemistry were reduced by hydrogen atom to 16 NO and then released to the main steam line under hydrogen water chemistry; and (iv) 16 N in the main steam under normal water chemistry could be suppressed one order of magnitude by addition of non-radioactive nitrous acid into the reactor water. (author)

Dual purpose wheat production with different levels of nitrogen topdressing

Directory of Open Access Journals (Sweden)

Éderson Luis Henz

2016-04-01

Full Text Available Currently, the practice of Crop-Livestock Integration is stimulated as a way of increasing the generation of foreign exchange for Brazil. Integrated systems improve land use efficiency as well as preserve, recover and increment or soil fertility. The aim of this research was to evaluate how different doses of nitrogen fertilization can affect production and quality of dual purpose wheat submitted to grazing. The experimental designed was randomized block with five treatments (0, 75, 150, 225 and 300 Kg N ha-1, like ammonium nitrate and four repetitions. The forage yield, the percentage crude protein (P=.0001 and acid detergent insoluble protein (P=.0054 had a linear increased because of the nitrogen addition doses. The crude protein percentage changed the estimate of all soluble carbohydrates (P=.0001 and non-fibrous carbohydrates (P=.0186, but did not influence the, nitrogen detergent fiber corrected with ash and proteins percentage contributing for content cell. The crops production (P=.0001 and the number of kernels per ear (P=.0001 showed significantly difference because of the nitrogen additions dose, increasing the number of fertile flowers. The nitrogen topdressing alters forage production, the chemical composition and the production of dual purpose wheat grains subjected to grazing.

Influence of nitrogen source on NDMA formation during chlorination of diuron.

Science.gov (United States)

Chen, Wei-Hsiang; Young, Thomas M

2009-07-01

N-Nitrosodimethylamine (NDMA) is formed during chlorination of water containing the herbicide diuron (N'-(3,4-dichlorophenyl)-N,N-dimethylurea) but formation is greatly enhanced in the presence of ammonia (chloramination). Groundwater impacted by agricultural runoff may contain diuron and relatively high total nitrogen concentrations; this study examines the impact of the nitrogen form (ammonium, nitrite or nitrate) on NDMA formation during chlorination of such waters. NDMA formation during chlorination of diuron increased in the order nitriteNDMA formation in the presence of ammonium. Nitrate unexpectedly enhanced nitrosation of diuron derivatives to form NDMA compared to the cases of no added nitrogen or nitrite addition. Nitrite addition is less effective because it consumes more chlorine and produces intermediates that react rapidly with diuron and its aromatic byproducts. Differences between surface water and groundwater in nitrogen forms and concentrations and disinfection approaches suggest strategies to reduce NDMA formation should vary with drinking water source.

Influence of Nitrogen Source on NDMA Formation during Chlorination of Diuron

Science.gov (United States)

Chen, Wei-Hsiang; Young, Thomas M.

2009-01-01

N-Nitrosodimethylamine (NDMA) is formed during chlorination of water containing the herbicide diuron (N′-(3,4-dichlorophenyl)-N, N-dimethylurea) but formation is greatly enhanced in the presence of ammonia (chloramination). Groundwater impacted by agricultural runoff may contain diuron and relatively high total nitrogen concentrations; this study examines the impact of the nitrogen form (ammonium, nitrite or nitrate) on NDMA formation during chlorination of such waters. NDMA formation during chlorination of diuron increased in the order nitrite diuron dose. Formation of dichloramine seemed to fully explain enhanced NDMA formation in the presence of ammonium. Nitrate unexpectedly enhanced nitrosation of diuron derivatives to form NDMA compared to the cases of no added nitrogen or nitrite addition. Nitrite addition is less effective because it consumes more chlorine and produces intermediates that react rapidly with diuron and its aromatic byproducts. Differences between surface and groundwater in nitrogen forms and concentrations and disinfection approaches, suggest strategies to reduce NDMA formation should vary with drinking water source. PMID:19457535

Natural abundance of 15N in barley as influenced by prior cropping or fallow, nitrogen fertilizer and tillage

International Nuclear Information System (INIS)

Doughton, J.A.; Saffigna, P.G.; Vallis, I.

1991-01-01

The 15 N abundance of nitrogen was measured in barley grown with 0,50 and 100 kg/ha of applied nitrogen after pretreatments of either fallow or grain sorghum, where sorghum stubble was either incorporated, removed or retained on the soil surface (zero-till). Barley 15 N abundance was assumed to reflect that of assimilated soil mineral nitrogen. 15 N enrichment was assumed to be mostly the result of isotope fractionation between 14 N and 15 N during denitrification of the large excess of NO 3 -N present prior to and during the experiment. Nitrogen fertilizer additions caused 15 N depletion of nitrogen in barley. However, where fertilizer additions resulted in excess availability of NO 3 -N, subsequent denitrification and 15 N enrichment of this NO 3 -N levels partially counterbalanced the 15 N depleting effect of fertilizer additions. Where soil NO 3 -N levels were low ( 3 -N/ha) following sorghum there were no differences in 15 N abundance of nitrogen in barley between tillage treatments. With additions of nitrogen fertilizer and the availability of excess NO 3 -N for denitrification, differences between tillage treatments occurred with some being significant. 27 refs., 6 tabs

The Effect of Percentage of Nitrogen in Plasma Gas on Nitrogen ...

African Journals Online (AJOL)

Increase in nitrogen percent in the plasma gas results in increased content of dissociated nitrogen and molecular nitrogen possessing excess vibrational energy and therefore the increased solution of nitrogen in the liquid iron. It would appear that above 35% nitrogen in the plasma gas, frequency of collisions of species in ...

Evaluation of the performance of the Tyson Foods wastewater treatment plant for nitrogen removal.

Science.gov (United States)

Ubay-Cokgor, E; Randall, C W; Orhon, D

2005-01-01

In this paper, the performance of the Tyson Foods wastewater treatment plant with an average flow rate of 6500 m3/d was evaluated before and after upgrading of the treatment system for nitrogen removal. This study was also covered with an additional recommendation of BIOWIN BNR program simulation after the modification period to achieve an additional nutrient removal. The results clearly show that the upgrading was very successful for improved nitrogen removal, with a 57% decrease on the total nitrogen discharge. There also were slight reductions in the discharged loads of biological oxygen demand, total suspended solids, ammonium and total phosphorus with denitrification, even though the effluent flow was higher during operation of the nitrogen removal configuration.

Hemispherical Scanning Imaging DOAS: Resolving nitrogen dioxide in the urban environment

Science.gov (United States)

Leigh, R. J.; Graves, R. R.; Lawrence, J.; Faloon, K.; Monks, P. S.

2012-12-01

Imaging DOAS techniques have been used for nitrogen dioxide and sulfer dioxide for a number of years. This presentation describes a novel system which images concentrations of nitrogen dioxide by scanning an imaging spectrometer 360 degrees azimuthally, covering a region from 5 degrees below the horizon, to the zenith. The instrument has been built at the University of Leicester (UK), on optical designs by Surrey Satellite Technologies Ltd, and incorporates an Offner relay with Schwarzchild fore-optics, in a rotating mount. The spectrometer offers high fidelity spectroscopic retrievals of nitrogen dioxide as a result of a reliable Gaussian line shape, zero smile and low chromatic aberration. The full hemispherical scanning provides complete coverage of nitrogen dioxide concentrations above approximately 5 ppbv in urban environments. Through the use of multiple instruments, the three-dimensional structure of nitrogen dioxide can be sampled and tomographically reconstructed, providing valuable information on nitrogen dioxide emissions and downwind exposure, in addition to new understanding of boundary layer dynamics through the use of nitrogen dioxide as a tracer. Furthermore, certain aerosol information can be retrieved through absolute intensity measurements in each azimuthal direction supplemented by traditional techniques of O4 spectroscopy. Such measurements provide a new tool for boundary layer measurement and monitoring at a time when air quality implications on human health and climate are under significant scrutiny. This presentation will describe the instrument and tomographic potential of this technique. First measurements were taken as part of the international PEGASOS campaign in Bologna, Italy. Results from these measurements will be shown, including imaging of enhanced NO2 in the Bologna urban boundary layer during a severe thunderstorm. A Hemispherical Scanning Imaging DOAS instrument operating in Bologna, Italy in June 2012. Visible in the background

Enhanced nitrogen deposition over China

Energy Technology Data Exchange (ETDEWEB)

Liu, Xuejun; Zhang, Ying; Han, Wenxuan; Tang, Aohan; Shen, Jianlin; Cui, Zhenling; Christie, Peter; Zhang, Fusuo [College of Resources and Environmental Sciences, China Agricultural University, Beijing 100193 (China); Vitousek, Peter [Department of Biology, Stanford University, Stanford, California 94305 (United States); Erisman, Jan Willem [VU University Amsterdam, 1081 HV Amsterdam (Netherlands); Goulding, Keith [The Sustainable Soils and Grassland Systems Department, Rothamsted Research, Harpenden AL5 2JQ (United Kingdom); Fangmeier, Andreas [Institute of Landscape and Plant Ecology, University of Hohenheim, 70593 Stuttgart (Germany)

2013-02-28

China is experiencing intense air pollution caused in large part by anthropogenic emissions of reactive nitrogen. These emissions result in the deposition of atmospheric nitrogen (N) in terrestrial and aquatic ecosystems, with implications for human and ecosystem health, greenhouse gas balances and biological diversity. However, information on the magnitude and environmental impact of N deposition in China is limited. Here we use nationwide data sets on bulk N deposition, plant foliar N and crop N uptake (from long-term unfertilized soils) to evaluate N deposition dynamics and their effect on ecosystems across China between 1980 and 2010. We find that the average annual bulk deposition of N increased by approximately 8 kilograms of nitrogen per hectare (P < 0.001) between the 1980s (13.2 kilograms of nitrogen per hectare) and the 2000s (21.1 kilograms of nitrogen per hectare). Nitrogen deposition rates in the industrialized and agriculturally intensified regions of China are as high as the peak levels of deposition in northwestern Europe in the 1980s, before the introduction of mitigation measures. Nitrogen from ammonium (NH4+) is the dominant form of N in bulk deposition, but the rate of increase is largest for deposition of N from nitrate (NO3-), in agreement with decreased ratios of NH3 to NOx emissions since 1980. We also find that the impact of N deposition on Chinese ecosystems includes significantly increased plant foliar N concentrations in natural and semi-natural (that is, non-agricultural) ecosystems and increased crop N uptake from long-term-unfertilized croplands. China and other economies are facing a continuing challenge to reduce emissions of reactive nitrogen, N deposition and their negative effects on human health and the environment.

Influence of the form and rate of 15N-labelled nitrogen fertilizers on nitrogen uptake by maize grown on two different soils

International Nuclear Information System (INIS)

Balabanova-Georgieva, R.; Ikonomova, E.

1996-01-01

The influence of 15 N-labelled urea and ammonium sulfate on the yield and uptake of fertilizer nitrogen and soil nitrogen by maize was studied under the conditions of pot experiments on calcareous black earth and leached black earth. The nitrogen fertilizers were applied in rates: N 1 =250 mg, N 2 =500 mg, N 3 =750 mg and N 4 =1000 mg/1 kg of soil, on phosphorus(P)-potassium(K) background (P=200 and K=600 mg/kg soil). When treating with N 3 and N 4 , the application of the whole nitrogen rate was compared with its split application. It was found that the form of the nitrogen fertilizer played no important role for the formation of the yield of biomass and the uptake of nitrogen with the yield when it is applied in low nitrogen rates and maize was grown on calcareous black earth. The yield of biomass and the uptake of nitrogen with the yield of maize reach their maximum under the conditions of calcareous black earth and high nitrogen rates applied as urea depressed the plants which proves the statement that in case of calcareous black earth application of ammonium sulfate should be preferred rather that urea, fertilization with which should be avoided. No depression of plants was observed under the conditions of leached black earth and application of high urea rates. The amount of nitrogen taken up is growing with the increasing of the nitrogen rate (excluding the N-treatment). The split application of high nitrogen rates increased notably the yield of maize-vegetation mass which proved the great ability of this crop for effective utilization of the nitrogen fertilizers when applied in portions and at suitable phases of plant vegetation. The role of the fertilizer nitrogen on the formation of the plant mass yield is much greater compared to that of the soil nitrogen; in the split application of urea the soil nitrogen plays a much bigger role than in its single application. The additional mobilization of the soil nitrogen under the influence of the applied nitrogen

The effect of nitrogen addition on biomass production and competition in three expansive tall grasses

Czech Academy of Sciences Publication Activity Database

Holub, Petr; Tůma, I.; Fiala, Karel

2012-01-01

Roč. 170, NOV 2012 (2012), s. 211-216 ISSN 0269-7491 R&D Projects: GA ČR(CZ) GA526/06/0556; GA MZe QJ1220007; GA MŠk(CZ) ED1.1.00/02.0073 Institutional support: RVO:67985939 ; RVO:67179843 Keywords : aboveground biomass * aggressivity * crowding coefficient * Nitrogen * tall grasses Subject RIV: EH - Ecology, Behaviour; EF - Botanics (BU-J) Impact factor: 3.730, year: 2012

Steady-state and dynamic gene expression programs in Saccharomyces cerevisiae in response to variation in environmental nitrogen

Science.gov (United States)

Airoldi, Edoardo M.; Miller, Darach; Athanasiadou, Rodoniki; Brandt, Nathan; Abdul-Rahman, Farah; Neymotin, Benjamin; Hashimoto, Tatsu; Bahmani, Tayebeh; Gresham, David

2016-01-01

Cell growth rate is regulated in response to the abundance and molecular form of essential nutrients. In Saccharomyces cerevisiae (budding yeast), the molecular form of environmental nitrogen is a major determinant of cell growth rate, supporting growth rates that vary at least threefold. Transcriptional control of nitrogen use is mediated in large part by nitrogen catabolite repression (NCR), which results in the repression of specific transcripts in the presence of a preferred nitrogen source that supports a fast growth rate, such as glutamine, that are otherwise expressed in the presence of a nonpreferred nitrogen source, such as proline, which supports a slower growth rate. Differential expression of the NCR regulon and additional nitrogen-responsive genes results in >500 transcripts that are differentially expressed in cells growing in the presence of different nitrogen sources in batch cultures. Here we find that in growth rate–controlled cultures using nitrogen-limited chemostats, gene expression programs are strikingly similar regardless of nitrogen source. NCR expression is derepressed in all nitrogen-limiting chemostat conditions regardless of nitrogen source, and in these conditions, only 34 transcripts exhibit nitrogen source–specific differential gene expression. Addition of either the preferred nitrogen source, glutamine, or the nonpreferred nitrogen source, proline, to cells growing in nitrogen-limited chemostats results in rapid, dose-dependent repression of the NCR regulon. Using a novel means of computational normalization to compare global gene expression programs in steady-state and dynamic conditions, we find evidence that the addition of nitrogen to nitrogen-limited cells results in the transient overproduction of transcripts required for protein translation. Simultaneously, we find that that accelerated mRNA degradation underlies the rapid clearing of a subset of transcripts, which is most pronounced for the highly expressed NCR

Genetic basis of nitrogen use efficiency and yield stability across environments in winter rapeseed.

Science.gov (United States)

Bouchet, Anne-Sophie; Laperche, Anne; Bissuel-Belaygue, Christine; Baron, Cécile; Morice, Jérôme; Rousseau-Gueutin, Mathieu; Dheu, Jean-Eric; George, Pierre; Pinochet, Xavier; Foubert, Thomas; Maes, Olivier; Dugué, Damien; Guinot, Florent; Nesi, Nathalie

2016-09-15

Nitrogen use efficiency is an important breeding trait that can be modified to improve the sustainability of many crop species used in agriculture. Rapeseed is a major oil crop with low nitrogen use efficiency, making its production highly dependent on nitrogen input. This complex trait is suspected to be sensitive to genotype × environment interactions, especially genotype × nitrogen interactions. Therefore, phenotyping diverse rapeseed populations under a dense network of trials is a powerful approach to study nitrogen use efficiency in this crop. The present study aimed to determine the quantitative trait loci (QTL) associated with yield in winter oilseed rape and to assess the stability of these regions under contrasting nitrogen conditions for the purpose of increasing nitrogen use efficiency. Genome-wide association studies and linkage analyses were performed on two diversity sets and two doubled-haploid populations. These populations were densely genotyped, and yield-related traits were scored in a multi-environment design including seven French locations, six growing seasons (2009 to 2014) and two nitrogen nutrition levels (optimal versus limited). Very few genotype × nitrogen interactions were detected, and a large proportion of the QTL were stable across nitrogen nutrition conditions. In contrast, strong genotype × trial interactions in which most of the QTL were specific to a single trial were found. To obtain further insight into the QTL × environment interactions, genetic analyses of ecovalence were performed to identify the genomic regions contributing to the genotype × nitrogen and genotype × trial interactions. Fifty-one critical genomic regions contributing to the additive genetic control of yield-associated traits were identified, and the structural organization of these regions in the genome was investigated. Our results demonstrated that the effect of the trial was greater than the effect of nitrogen nutrition

First principles investigation of nitrogenated holey graphene

Science.gov (United States)

Xu, Cui-Yan; Dong, Hai-Kuan; Shi, Li-Bin

2018-04-01

The zero band gap problem limits the application of graphene in the field of electronic devices. Opening the band gap of graphene has become a research issue. Nitrogenated holey graphene (NHG) has attracted much attention because of its semiconducting properties. However, the stacking orders and defect properties have not been investigated. In this letter, the structural and stacking properties of NHG are first investigated. We obtain the most stable stacking structure. Then, the band structures for bulk and multilayer NHG are studied. Impact of the strain on the band gaps and bond characteristics is discussed. In addition, we investigate formation mechanism of native defects of carbon vacancy (VC), carbon interstitial (Ci), nitrogen vacancy (VN), and nitrogen interstitial (Ni) in bulk NHG. Formation energies and transition levels of these native defects are assessed.

Nitrogen recycling and methane production using Gracilaria tikvahiae: a closed system approach

Energy Technology Data Exchange (ETDEWEB)

Habig, C.; Andrews, D.A.; Ryther, J.H.

1984-01-01

The macroalga Gracilaria tikvahiae (Rhodophyta) was used in a closed system of materials to study methane production and nitrogen recycling. Twenty liter carboys served as digesters. The performance of these digesters mirrors results obtained with two- and four litre Gracilaria digesters with respect to optimal retention times for biogas production, methane content, and bioconversion efficiency to methane. Three groups of Gracilaria were cultivated in 850-L vaults to compare growth performance under three different enrichment treatments. These treatments consisted of an unfertilized group, a group raised on a typical commercial enrichment regime, and a group raised on the residues removed from the digester when additional substrate was loaded into the digester. The results indicate that growth of Gracilaria on the digester residue enrichment scheme is statistically similar to growth using a commercial enrichment mixture. In addition, the nitrogen content of the digester residue is described, along with nitrogen assimilation by Gracilaria and nitrogen recycling efficiencies. Both nitrogen assimilation and recycling efficiency closely parallel the ammonium content of the residue enrichment media. (Refs. 18).

Rapid estimation of organic nitrogen in oil shale waste waters

Energy Technology Data Exchange (ETDEWEB)

Jones, B.M.; Daughton, C.G.; Harris, G.J.

1984-04-01

Many of the characteristics of oil shale process waste waters (e.g., malodors, color, and resistance to biotreatment) are imparted by numerous nitrogenous heterocycles and aromatic amines. For the frequent performance assessment of waste treatment processes designed to remove these nitrogenous organic compounds, a rapid and colligative measurement of organic nitrogen is essential. Quantification of organic nitrogen in biological and agricultural samples is usually accomplished using the time-consuming, wet-chemical Kjeldahl method. For oil shale waste waters, whose primary inorganic nitorgen constituent is amonia, organic Kjeldahl nitrogen (OKN) is determined by first eliminating the endogenous ammonia by distillation and then digesting the sample in boiling H/sub 2/SO/sub 4/. The organic material is oxidized, and most forms of organically bound nitrogen are released as ammonium ion. After the addition of base, the ammonia is separated from the digestate by distillation and quantified by acidimetric titrimetry or colorimetry. The major failings of this method are the loss of volatile species such as aliphatic amines (during predistillation) and the inability to completely recover nitrogen from many nitrogenous heterocycles (during digestion). Within the last decade, a new approach has been developed for the quantification of total nitrogen (TN). The sample is first combusted, a

Key ecological responses to nitrogen are altered by climate change

Science.gov (United States)

Greaver, T.L.; Clark, C.M.; Compton, J.E.; Vallano, D.; Talhelm, A. F.; Weaver, C.P.; Band, L.E.; Baron, Jill S.; Davidson, E.A.; Tague, C.L.; Felker-Quinn, E.; Lynch, J.A.; Herrick, J.D.; Liu, L.; Goodale, C.L.; Novak, K. J.; Haeuber, R. A.

2016-01-01

Climate change and anthropogenic nitrogen deposition are both important ecological threats. Evaluating their cumulative effects provides a more holistic view of ecosystem vulnerability to human activities, which would better inform policy decisions aimed to protect the sustainability of ecosystems. Our knowledge of the cumulative effects of these stressors is growing, but we lack an integrated understanding. In this Review, we describe how climate change alters key processes in terrestrial and freshwater ecosystems related to nitrogen cycling and availability, and the response of ecosystems to nitrogen addition in terms of carbon cycling, acidification and biodiversity.

Effects of sewage sludge addition to Norway spruce seedlings on nitrogen availability and soil fauna in clear-cut areas.

Science.gov (United States)

Nieminen, Jouni K; Räisänen, Mikko

2013-07-01

Anaerobically digested and composted sewage sludge (CSS) has been suggested to be a slow-release fertilizer in forestry and an alternative to quick-release inorganic fertilizers. The effects of CSS with or without added carbohydrate on inorganic nitrogen availability and on soil animals were tested in two Norway spruce plantations. Half of the seedlings were individually fertilized with CSS, and the rest were left as controls. Solid sucrose was added to half of the fertilized and untreated seedlings. Soil samples were taken in the autumn in the first and the second year after the treatments. CSS increased soil NH4-N (2100%), the proportion of soil NO3-N, and the N concentration of spruce needles. CSS greatly reduced the abundances of enchytraeids, tardigrades and collembolans, but increased the proportion and abundance of bacterial-feeding nematodes irrespective of carbohydrate addition. A better stabilization method needs to be developed before CSS can be used as a forest fertilizer. Copyright © 2013 Elsevier Ltd. All rights reserved.

Nitrogen cycling in a 15N-fertilized bean (Phaseolus vulgaris L.) crop

International Nuclear Information System (INIS)

Victoria, R.L.; Libardi, P.L.; Reichardt, K.; Cervellini, A.

1982-01-01

To increase our understanding of the fate of applied nitrogen in Phaseolus vulgaris crops grown under tropical conditions, 15 N-labelled urea was applied to bean crops and followed for three consecutive cropping periods. Each crop received 100 kg urea-N ha - 1 and 41 kg KCl-K ha - 1 . At the end of each period we estimated each crop's recovery of the added nitrogen, the residual effects of nitrogen from the previous cropping period, the distribution of nitrogen in the soil profile, and leaching losses of nitrogen. In addition, to evaluate potential effects of added phosphorus on nitrogen cycling in this crop, beans were treated at planting with either 35 kg rock-phosphate-P, 35 kg superphosphate-P, or 0 kg P ha - 1 . Results showed that 31.2% of the nitrogen in the first crop was derived from the applied urea, which represents a nitrogen utilization efficiency of 38.5%, 6.2% of the nitrogen in the second crop was derived from fertilizer applied to the first crop, and 1.4% of the nitrogen in the third crop. (orig./AJ)

The value of symbiotic nitrogen fixation by grain legumes in comparison to the cost of nitrogen fertilizer used in developing countries

International Nuclear Information System (INIS)

Hardarson, G.; Bunning, S.; Montanez, A.; Roy, R.; MacMillan, A.

2001-01-01

A great challenge lies in devising more sustainable farming systems without compromising food production levels and food security. Obviously, increasing productivity is necessary to accommodate growth in the global population. World wide, the environmental factors that most severely restrict plant growth are the availability of water and nitrogen. The challenges in developing countries are to find ways of meeting this additional nitrogen demand without concomitant degrading natural productivity. Widespread adoption of biological nitrogen fixation (BNF) would contribute to this goal. BNF, together with adequate N management in the ecosystem, appears to be the most promising alternative to increasing the use of inorganic fertiliser nitrogen. BNF technologies represent economic, sustainable and environmentally friendly means of ensuring the nitrogen requirement of an agro-ecosystem. Here we investigate the value of BNF by grain legumes and compares it to the cost of nitrogen fertilizer used in developing countries. Our data show that major grain legumes fix approximately 11.1 million metric tons of nitrogen per annum in developing countries. If this N was supplied by inorganic fertiliser one would have to apply at least double that amount to achieve the same yields, and this would cost approximately 6.7 billion US dollars. As the eight major grain legumes grown in developing countries contribute 30 - 40% of the annual N requirement the contribution of BNF is of great economic and environmental importance. (author)

Effects from additives on deacetylation of chitin

International Nuclear Information System (INIS)

Campana Filho, Sergio P.; Signini, Roberta

2001-01-01

Deacetylation reactions of commercial chitin were carried out in aqueous sodium hydroxide solution at 115 deg C for 6 hours. The effect from additives (sodium borohydride or anthraquinone) and of bubbling inert gas (nitrogen or argon) on the characteristics of deacetylated samples were evaluated. Average degrees of acetylation and intrinsic viscosity were determined by 1 H NMR spectroscopy and capillary viscometry, respectively. X-ray diffraction was employed to evaluate changes in crystallinity and infrared spectroscopy was used to monitor structural changes due to deacetylation. The bubbling of inert gas during the deacetylation reaction resulted in more crystalline samples of chitosan. Deacetylation carried out without any additive produced slightly more deacetylated chitosan but they were severely depolymerized. The depolymerization process was much less important when sodium borohydride was added to the reaction medium but the addition of anthraquinone and the bubbling of nitrogen, or argon, did not have any effect, this suggests that oxygen is not required for depolymerization. (author)

Next Generation Carbon-Nitrogen Dynamics Model

Science.gov (United States)

Xu, C.; Fisher, R. A.; Vrugt, J. A.; Wullschleger, S. D.; McDowell, N. G.

2012-12-01

Nitrogen is a key regulator of vegetation dynamics, soil carbon release, and terrestrial carbon cycles. Thus, to assess energy impacts on the global carbon cycle and future climates, it is critical that we have a mechanism-based and data-calibrated nitrogen model that simulates nitrogen limitation upon both above and belowground carbon dynamics. In this study, we developed a next generation nitrogen-carbon dynamic model within the NCAR Community Earth System Model (CESM). This next generation nitrogen-carbon dynamic model utilized 1) a mechanistic model of nitrogen limitation on photosynthesis with nitrogen trade-offs among light absorption, electron transport, carboxylation, respiration and storage; 2) an optimal leaf nitrogen model that links soil nitrogen availability and leaf nitrogen content; and 3) an ecosystem demography (ED) model that simulates the growth and light competition of tree cohorts and is currently coupled to CLM. Our three test cases with changes in CO2 concentration, growing temperature and radiation demonstrate the model's ability to predict the impact of altered environmental conditions on nitrogen allocations. Currently, we are testing the model against different datasets including soil fertilization and Free Air CO2 enrichment (FACE) experiments across different forest types. We expect that our calibrated model will considerably improve our understanding and predictability of vegetation-climate interactions.itrogen allocation model evaluations. The figure shows the scatter plots of predicted and measured Vc,max and Jmax scaled to 25 oC (i.e.,Vc,max25 and Jmax25) at elevated CO2 (570 ppm, test case one), reduced radiation in canopy (0.1-0.9 of the radiation at the top of canopy, test case two) and reduced growing temperature (15oC, test case three). The model is first calibrated using control data under ambient CO2 (370 ppm), radiation at the top of the canopy (621 μmol photon/m2/s), the normal growing temperature (30oC). The fitted model

Total Nitrogen in Surface Water

Data.gov (United States)

U.S. Environmental Protection Agency — Excess nitrogen in surface water can result in eutrophication. TOTALN is reported in kilograms/hectare/year. More information about these resources, including the...

The geobiological nitrogen cycle: From microbes to the mantle.

Science.gov (United States)

Zerkle, A L; Mikhail, S

2017-05-01

Nitrogen forms an integral part of the main building blocks of life, including DNA, RNA, and proteins. N 2 is the dominant gas in Earth's atmosphere, and nitrogen is stored in all of Earth's geological reservoirs, including the crust, the mantle, and the core. As such, nitrogen geochemistry is fundamental to the evolution of planet Earth and the life it supports. Despite the importance of nitrogen in the Earth system, large gaps remain in our knowledge of how the surface and deep nitrogen cycles have evolved over geologic time. Here, we discuss the current understanding (or lack thereof) for how the unique interaction of biological innovation, geodynamics, and mantle petrology has acted to regulate Earth's nitrogen cycle over geologic timescales. In particular, we explore how temporal variations in the external (biosphere and atmosphere) and internal (crust and mantle) nitrogen cycles could have regulated atmospheric pN 2 . We consider three potential scenarios for the evolution of the geobiological nitrogen cycle over Earth's history: two in which atmospheric pN 2 has changed unidirectionally (increased or decreased) over geologic time and one in which pN 2 could have taken a dramatic deflection following the Great Oxidation Event. It is impossible to discriminate between these scenarios with the currently available models and datasets. However, we are optimistic that this problem can be solved, following a sustained, open-minded, and multidisciplinary effort between surface and deep Earth communities. © 2017 The Authors Geobiology Published by John Wiley & Sons Ltd.

A Systems Approach to Nitrogen Delivery

Energy Technology Data Exchange (ETDEWEB)

Goins, Bobby [Y-12 National Security Complex, Oak Ridge, TN (United States)

2017-10-23

A systems based approach will be used to evaluate the nitrogen delivery process. This approach involves principles found in Lean, Reliability, Systems Thinking, and Requirements. This unique combination of principles and thought process yields a very in depth look into the system to which it is applied. By applying a systems based approach to the nitrogen delivery process there should be improvements in cycle time, efficiency, and a reduction in the required number of personnel needed to sustain the delivery process. This will in turn reduce the amount of demurrage charges that the site incurs. In addition there should be less frustration associated with the delivery process.

A Systems Approach to Nitrogen Delivery

Energy Technology Data Exchange (ETDEWEB)

Goins, Bobby [Y-12 National Security Complex, Oak Ridge, TN (United States); Univ. of Tennessee, Knoxville, TN (United States)

2017-10-17

A systems based approach will be used to evaluate the nitrogen delivery process. This approach involves principles found in Lean, Reliability, Systems Thinking, and Requirements. This unique combination of principles and thought process yields a very in depth look into the system to which it is applied. By applying a systems based approach to the nitrogen delivery process there should be improvements in cycle time, efficiency, and a reduction in the required number of personnel needed to sustain the delivery process. This will in turn reduce the amount of demurrage charges that the site incurs. In addition there should be less frustration associated with the delivery process.

The release of nitrogen in coal combustion and pyrolysis

International Nuclear Information System (INIS)

Varey, J.E.; Hindmarsh, C.J.; Thomas, K.M.

1994-01-01

Environmental aspects of coal utilization are a major concern. Recent advances in the development of low NO x burners and the emerging technologies of fluidized bed combustion have led to the identification of coal char nitrogen as the major contributor to the nitrogen oxides released during combustion. The temperature programmed combustion and pyrolysis of a series of coals covering a wide range of rank have been investigated. In addition, maceral concentrates have been investigated to assess the variation in the combustion behavior and the release of nitrogen in the pyrolysis and combustion of macerals. This investigation has involved the use of thermogravimetric analysis - mass spectrometry (TG-MS) with two sampling options: (1) ∼1cm from the sample and (2) at the exit of the TG. The former allows reactive species to be identified in the combustion of the coals. These temperature programmed combustion results have been compared with similar measurements carried out at the exit of the TG where the products are at equilibrium. In addition, pyrolysis studies have been carried out under similar conditions. The results show that reactive intermediate species such as HCN, (CN) 2 , COS etc. can be detected in the combustion products. The evolution of these species during combustion are compared with the pyrolysis products of the coal. The results are discussed in relation to the structure of the coals and the conversion of volatile species and char nitrogen to nitrogen oxides

Terrestrial nitrogen-carbon cycle interactions at the global scale.

Science.gov (United States)

Zaehle, S

2013-07-05

Interactions between the terrestrial nitrogen (N) and carbon (C) cycles shape the response of ecosystems to global change. However, the global distribution of nitrogen availability and its importance in global biogeochemistry and biogeochemical interactions with the climate system remain uncertain. Based on projections of a terrestrial biosphere model scaling ecological understanding of nitrogen-carbon cycle interactions to global scales, anthropogenic nitrogen additions since 1860 are estimated to have enriched the terrestrial biosphere by 1.3 Pg N, supporting the sequestration of 11.2 Pg C. Over the same time period, CO2 fertilization has increased terrestrial carbon storage by 134.0 Pg C, increasing the terrestrial nitrogen stock by 1.2 Pg N. In 2001-2010, terrestrial ecosystems sequestered an estimated total of 27 Tg N yr(-1) (1.9 Pg C yr(-1)), of which 10 Tg N yr(-1) (0.2 Pg C yr(-1)) are due to anthropogenic nitrogen deposition. Nitrogen availability already limits terrestrial carbon sequestration in the boreal and temperate zone, and will constrain future carbon sequestration in response to CO2 fertilization (regionally by up to 70% compared with an estimate without considering nitrogen-carbon interactions). This reduced terrestrial carbon uptake will probably dominate the role of the terrestrial nitrogen cycle in the climate system, as it accelerates the accumulation of anthropogenic CO2 in the atmosphere. However, increases of N2O emissions owing to anthropogenic nitrogen and climate change (at a rate of approx. 0.5 Tg N yr(-1) per 1°C degree climate warming) will add an important long-term climate forcing.

Monitoring plant tissue nitrogen isotopes to assess nearshore inputs of nitrogen to Lake Crescent, Olympic National Park, Washington

Science.gov (United States)

Cox, Stephen E.; Moran, Patrick W.; Huffman, Raegan L.; Fradkin, Steven C.

2016-05-31

Mats of filamentous-periphytic algae present in some nearshore areas of Lake Crescent, Olympic National Park, Washington, may indicate early stages of eutrophication from nutrient enrichment of an otherwise highly oligotrophic lake. Natural abundance ratios of stable isotopes of nitrogen (δ15N) measured in plant tissue growing in nearshore areas of the lake indicate that the major source of nitrogen used by these primary producing plants is derived mainly from atmospherically fixed nitrogen in an undeveloped forested ecosystem. Exceptions to this pattern occurred in the Barnes Point area where elevated δ15N ratios indicate that effluent from septic systems also contribute nitrogen to filamentous-periphytic algae growing in the littoral zone of that area. Near the Lyre River outlet of Lake Crescent, the δ15N of filamentous-periphytic algae growing in close proximity to the spawning areas of a unique species of trout show little evidence of elevated δ15N indicating that nitrogen from on-site septic systems is not a substantial source of nitrogen for these plants. The δ15N data corroborate estimates that nitrogen input to Lake Crescent from septic sources is comparatively small relative to input from motor vehicle exhaust and vegetative sources in undeveloped forests, including litterfall, pollen, and symbiotic nitrogen fixation. The seasonal timing of blooms of filamentous-periphytic algal near the lake shoreline is also consistent with nitrogen exported from stands of red alder trees (Alnus rubra). Isotope biomonitoring of filamentous-periphytic algae may be an effective approach to monitoring the littoral zone for nutrient input to Lake Crescent from septic sources.

Controls on Biogeochemical Cycling of Nitrogen in Urban Ecosystems

Science.gov (United States)

Templer, P. H.; Hutyra, L.; Decina, S.; Rao, P.; Gately, C.

2017-12-01

Rates of atmospheric nitrogen deposition are declining across much of the United States and Europe, yet they remain substantially elevated by almost an order of magnitude over pre-industrial levels and occur as hot spots in urban areas. We measured atmospheric inputs of inorganic and organic nitrogen in multiple urban sites around the Boston Metropolitan area, finding that urban rates are substantially elevated compared to nearby rural areas, and that the range of these atmospheric inputs are as large as observed urban to rural gradients. Within the City of Boston, the variation in deposition fluxes can be explained by traffic intensity, vehicle emissions, and spring fertilizer additions. Throughfall inputs of nitrogen are approximately three times greater than bulk deposition inputs in the city, demonstrating that the urban canopy amplifies rates of nitrogen reaching the ground surface. Similar to many other metropolitan areas of the United States, the City of Boston has 25% canopy cover; however, 25% of this tree canopy is located above impervious pavement. Throughfall inputs that do not have soil below the canopy to retain excess nitrogen may lead to greater inputs of nitrogen into nearby waterways through runoff. Most measurement stations for atmospheric nitrogen deposition are intentionally located away from urban areas and point sources of pollution to capture regional trends. Our data show that a major consequence of this network design is that hotspots of nitrogen deposition and runoff into urban and coastal waterways is likely underestimated to a significant degree. A more complete determination of atmospheric nitrogen deposition and its fate in urban ecosystems is critical for closing regional nitrogen budgets and for improving our understanding of biogeochemical nitrogen cycling across multiple spatial scales.

Buckminsterfullerenes: a non-metal system for nitrogen fixation.

Science.gov (United States)

Nishibayashi, Yoshiaki; Saito, Makoto; Uemura, Sakae; Takekuma, Shin-Ichi; Takekuma, Hideko; Yoshida, Zen-Ichi

2004-03-18

In all nitrogen-fixation processes known so far--including the industrial Haber-Bosch process, biological fixation by nitrogenase enzymes and previously described homogeneous synthetic systems--the direct transformation of the stable, inert dinitrogen molecule (N2) into ammonia (NH3) relies on the powerful redox properties of metals. Here we show that nitrogen fixation can also be achieved by using a non-metallic buckminsterfullerene (C60) molecule, in the form of a water-soluble C60:gamma-cyclodextrin (1:2) complex, and light under nitrogen at atmospheric pressure. This metal-free system efficiently fixes nitrogen under mild conditions by making use of the redox properties of the fullerene derivative.

Nitrogen concentration estimation with hyperspectral LiDAR

Directory of Open Access Journals (Sweden)

O. Nevalainen

2013-10-01

Full Text Available Agricultural lands have strong impact on global carbon dynamics and nitrogen availability. Monitoring changes in agricultural lands require more efficient and accurate methods. The first prototype of a full waveform hyperspectral Light Detection and Ranging (LiDAR instrument has been developed at the Finnish Geodetic Institute (FGI. The instrument efficiently combines the benefits of passive and active remote sensing sensors. It is able to produce 3D point clouds with spectral information included for every point which offers great potential in the field of remote sensing of environment. This study investigates the performance of the hyperspectral LiDAR instrument in nitrogen estimation. The investigation was conducted by finding vegetation indices sensitive to nitrogen concentration using hyperspectral LiDAR data and validating their performance in nitrogen estimation. The nitrogen estimation was performed by calculating 28 published vegetation indices to ten oat samples grown in different fertilization conditions. Reference data was acquired by laboratory nitrogen concentration analysis. The performance of the indices in nitrogen estimation was determined by linear regression and leave-one-out cross-validation. The results indicate that the hyperspectral LiDAR instrument holds a good capability to estimate plant biochemical parameters such as nitrogen concentration. The instrument holds much potential in various environmental applications and provides a significant improvement to the remote sensing of environment.

Myeloid-derived suppressor cells in murine AIDS inhibit B-cell responses in part via soluble mediators including reactive oxygen and nitrogen species, and TGF-β

Energy Technology Data Exchange (ETDEWEB)

Rastad, Jessica L. [Department of Microbiology and Immunology, Geisel School of Medicine at Dartmouth, Lebanon, NH 03756 (United States); Green, William R., E-mail: William.R.Green@dartmouth.edu [Department of Microbiology and Immunology, Geisel School of Medicine at Dartmouth, Lebanon, NH 03756 (United States); Norris Cotton Cancer Center, Geisel School of Medicine at Dartmouth, Lebanon, NH 03756 (United States)

2016-12-15

Monocytic myeloid-derived suppressor cells (M-MDSCs) were increased during LP-BM5 retroviral infection, and were capable of suppressing not only T-cell, but also B-cell responses. In addition to previously demonstrating iNOS- and VISTA-dependent M-MDSC mechanisms, in this paper, we detail how M-MDSCs utilized soluble mediators, including the reactive oxygen and nitrogen species superoxide, peroxynitrite, and nitric oxide, and TGF-β, to suppress B cells in a predominantly contact-independent manner. Suppression was independent of cysteine-depletion and hydrogen peroxide production. When two major mechanisms of suppression (iNOS and VISTA) were eliminated in double knockout mice, M-MDSCs from LP-BM5-infected mice were able to compensate using other, soluble mechanisms in order to maintain suppression of B cells. The IL-10 producing regulatory B-cell compartment was among the targets of M-MDSC-mediated suppression. -- Highlights: •LP-BM5-expanded M-MDSCs utilized soluble mediators nitric oxide, superoxide, peroxynitrite, and TGF-β to suppress B cells. •When two major mechanisms of suppression were eliminated through knockouts, M-MDSCs maintained suppression. •M-MDSCs from LP-BM5-infected mice decreased proliferation of IL-10 producing regulatory B cells.

Myeloid-derived suppressor cells in murine AIDS inhibit B-cell responses in part via soluble mediators including reactive oxygen and nitrogen species, and TGF-β

International Nuclear Information System (INIS)

Rastad, Jessica L.; Green, William R.

2016-01-01

Monocytic myeloid-derived suppressor cells (M-MDSCs) were increased during LP-BM5 retroviral infection, and were capable of suppressing not only T-cell, but also B-cell responses. In addition to previously demonstrating iNOS- and VISTA-dependent M-MDSC mechanisms, in this paper, we detail how M-MDSCs utilized soluble mediators, including the reactive oxygen and nitrogen species superoxide, peroxynitrite, and nitric oxide, and TGF-β, to suppress B cells in a predominantly contact-independent manner. Suppression was independent of cysteine-depletion and hydrogen peroxide production. When two major mechanisms of suppression (iNOS and VISTA) were eliminated in double knockout mice, M-MDSCs from LP-BM5-infected mice were able to compensate using other, soluble mechanisms in order to maintain suppression of B cells. The IL-10 producing regulatory B-cell compartment was among the targets of M-MDSC-mediated suppression. -- Highlights: •LP-BM5-expanded M-MDSCs utilized soluble mediators nitric oxide, superoxide, peroxynitrite, and TGF-β to suppress B cells. •When two major mechanisms of suppression were eliminated through knockouts, M-MDSCs maintained suppression. •M-MDSCs from LP-BM5-infected mice decreased proliferation of IL-10 producing regulatory B cells.

Broadening the ecological context of ungulate-ecosystem interactions: the importance of space, seasonality, and nitrogen.

Science.gov (United States)

Murray, Bryan D; Webster, Christopher R; Bump, Joseph K

2013-06-01

Spatial heterogeneity of soil resources, particularly nitrogen availability, affects herbaceous-layer cover and diversity in temperate forest ecosystems. Current hypotheses predict that ungulate herbivores influence nitrogen availability at the stand scale, but how ungulates affect nitrogen availability at finer spatial scales that are relevant to the herb layer is less understood. We tested the hypothesis that ungulate exclusion reduces the spatial complexity of nitrogen availability at neighborhood scales (1-26 m) apart from mean stand scale effects. This outcome was expected due to a lack of ungulate nitrogenous waste deposition within exclosures and seasonally variable ungulate habitat use. To test this hypothesis we examined spatial patterning of ammonium and nitrate availability, herb-layer cover and diversity, and under-canopy solar radiation using geostatistical models. Our study sites included six stands of eastern hemlock (Tsuga canadensis) forest: three where white-tailed deer (Odocoileus virginianus) were excluded and three that were accessible to deer. Where deer were present, patch sizes of ammonium availability, cover, and diversity were smaller compared to deer exclosures, whereas mean site-level effects were not significant. Within deer exclosures cover and solar radiation were more similar in patch size than were cover and nitrogen availability. Our results suggest that browsing ungulates affect spatial patterns of herb-layer cover and diversity through the excretion of nitrogenous wastes in small, discrete patches. Ungulate-excreted nitrogen deposition and herbivory were concentrated in the dormant season, allowing herb-layer plants a greater opportunity to benefit from nitrogen additions. Therefore, the impact of ungulates on nitrogen cycling in forest ecosystems varies with spatial scale and the seasonal timing of ungulate impacts. In this way, ungulates may function as a seasonally dependent link between fine-scale and landscape

Food, Feed and Fuel: a Story About Nitrogen

Science.gov (United States)

Galloway, J. N.; Burke, M. B.; Mooney, H. A.; Steinfeld, H.

2008-12-01

Humans obtain metabolic energy by eating food. Nitrogen is required to grow food, but natural supplies of N for human purposes have been inadequate since the beginning of the twentieth century. The Haber-Bosch process now provides a virtually inexhaustible supply of nitrogen, limited primarily by the cost of energy. However, most nitrogen used in food production is lost to the environment, where it cascades through environmental reservoirs contributing to many of the major environmental issues of the day. Furthermore, growing international trade in nitrogen-containing commodities is increasingly replacing wind and water as an important international transporter of nitrogen around the globe. Finally, the rapid growth in crop-based biofuels, and its attendant effects on the global production and trade of all agricultural commodities, could greatly affect global patterns of N use and loss. In the light of the findings above, this paper examines the role of nitrogen in food, feed and fuel production. It describes the beneficial consequences for food production and the negative consequences associated with the commodity nitrogen cascade and the environmental nitrogen cascade. The paper reviews estimates of future projections of nitrogen demands for food and fuel, including the impact of changing diets in the developing world. The paper concludes by presenting the potential interactions among global change, agricultural production and the nitrogen and carbon cycles.

Fired products of Cr-smectite clays in nitrogen

OpenAIRE

C. Volzone; A. M. Cesio

2004-01-01

The products of Cr-smectite clays heated to 1350 ° C in nitrogen were evaluated by X-ray diffraction and chemical analysis. Cr-smectite clays were prepared at room temperature by contact between smectite clays and Cr species contained in OH-Cr solutions. The Cr species were prepared using chromium nitrate solution by addition of NaOH solution with OH/Cr = 2. Products of firing in nitrogen at the high temperature were different (magnesia chromite, donathite, iron chromium oxide and picrochromi...

Changes in microbial community characteristics and soil organic matter with nitrogen additions in two tropical forests

Science.gov (United States)

Daniela F. Cusack; Whendee L. Silver; Margaret S. Torn; Sarah D. Burton; Mary K. Firestone

2011-01-01

Microbial communities and their associated enzyme activities affect the amount and chemical quality of carbon (C) in soils. Increasing nitrogen (N) deposition, particularly in N-rich tropical forests, is likely to change the composition and behavior of microbial communities and feed back on ecosystem structure and function. This study presents a novel assessment of...

Aminodisulfides as additives to lubricants

Energy Technology Data Exchange (ETDEWEB)

Balin, A.I.; Tarasevich, V.B.; Veretenova, T.N.

1980-01-01

A study was carried out and tehcnology developed for producing sulfur-nitrogen containing additives of the type of aminodisulfide by interaction of beta, beta-dichlordialkyl (aryl) disulfides with diethanolamine in a medium of sulfur-diethanolamine. The 2,2'-bis-(diethanol)-dialkyl(aryl) disulfides obtained do not hydrolyze in aqueous soltuions of alkalis, exhibit rather high antiscoring properties and are recommended for tests as active additives of high pressure to SOZH and technological lubricants of the oil and emulsion types.

Effects of short-term warming and nitrogen addition on the quantity and quality of dissolved organic matter in a subtropical Cunninghamia lanceolata plantation

Science.gov (United States)

Yuan, Xiaochun; Si, Youtao; Lin, Weisheng; Yang, Jingqing; Wang, Zheng; Zhang, Qiufang; Qian, Wei; Yang, Yusheng

2018-01-01

Increasing temperature and nitrogen (N) deposition are two large-scale changes projected to occur over the coming decades. The effects of these changes on dissolved organic matter (DOM) are largely unknown. This study aimed to assess the effects of warming and N addition on the quantity and quality of DOM from a subtropical Cunninghamia lanceolata plantation. Between 2014 and 2016, soil solutions were collected from 0–15, 15–30, and 30–60 cm depths by using a negative pressure sampling method. The quantity and quality of DOM were measured under six different treatments. The spectra showed that the DOM of the forest soil solution mainly consisted of aromatic protein-like components, microbial degradation products, and negligible amounts of humic-like substances. Warming, N addition, and warming + N addition significantly inhibited the concentration of dissolved organic carbon (DOC) in the surface (0–15 cm) soil solution. Our results suggested that warming reduced the amount of DOM originating from microbes. The decrease in protein and carboxylic acid contents was mostly attributed to the reduction of DOC following N addition. The warming + N addition treatment showed an interactive effect rather than an additive effect. Thus, short-term warming and warming + N addition decreased the quantity of DOM and facilitated the migration of nutrients to deeper soils. Further, N addition increased the complexity of the DOM structure. Hence, the loss of soil nutrients and the rational application of N need to be considered in order to prevent the accumulation of N compounds in soil. PMID:29360853

Cosmological evolution of the nitrogen abundance

Science.gov (United States)

Vangioni, Elisabeth; Dvorkin, Irina; Olive, Keith A.; Dubois, Yohan; Molaro, Paolo; Petitjean, Patrick; Silk, Joe; Kimm, Taysun

2018-06-01

The abundance of nitrogen in the interstellar medium is a powerful probe of star formation processes over cosmological time-scales. Since nitrogen can be produced both in massive and intermediate-mass stars with metallicity-dependent yields, its evolution is challenging to model, as evidenced by the differences between theoretical predictions and observations. In this work, we attempt to identify the sources of these discrepancies using a cosmic evolution model. To further complicate matters, there is considerable dispersion in the abundances from observations of damped Lyα absorbers (DLAs) at z ˜ 2-3. We study the evolution of nitrogen with a detailed cosmic chemical evolution model and find good agreement with these observations, including the relative abundances of (N/O) and (N/Si). We find that the principal contribution of nitrogen comes from intermediate-mass stars, with the exception of systems with the lowest N/H, where nitrogen production might possibly be dominated by massive stars. This last result could be strengthened if stellar rotation which is important at low metallicity can produce significant amounts of nitrogen. Moreover, these systems likely reside in host galaxies with stellar masses below 108.5 M⊙. We also study the origin of the observed dispersion in nitrogen abundances using the cosmological hydrodynamical simulations Horizon-AGN. We conclude that this dispersion can originate from two effects: difference in the masses of the DLA host galaxies, and difference in their position inside the galaxy.

Effects of nitrogen addition on soil fauna communities in Larix gmelinii and Fraxinus mandshurica plantations

OpenAIRE

Haifeng Zhuang; Yue Sun; Jiacun Gu; Yang Xu; Zhengquan Wang

2010-01-01

Soil fauna play a key role in regulating carbon allocation and nutrient cycling in terrestrial ecosystems. As soil fauna are sensitive to environmental changes, increases in soil nitrogen (N) availability resulting from global changes may profoundly influence the structure and function of soil faunal communities. However, the response of soil fauna in forest ecosystems to increases in soil N availability is still poorly understood. In order to explore the relationship between soil N availabil...

Ammonia Nitrogen Added to Diets Deficient in Dispensable Amino Acid Nitrogen Is Poorly Utilized for Urea Production in Growing Pigs.

Science.gov (United States)

Mansilla, Wilfredo D; Silva, Kayla E; Zhu, Cuilan L; Nyachoti, Charles M; Htoo, John K; Cant, John P; de Lange, Cornelis Fm

2017-12-01

Background: Including ammonia in low-crude protein (CP) diets deficient in dispensable amino acid (DAAs) increases nitrogen retention in growing pigs. Objective: We investigated the absorption and metabolism of dietary ammonia nitrogen in the portal-drained viscera (PDV) and liver of pigs fed a diet deficient in DAA nitrogen. Methods: Eight pigs with an initial mean ± SD body weight (BW) of 26.5 ± 1.4 kg were surgically fitted with 4 catheters each (portal, hepatic and mesenteric veins, and carotid artery). The pigs were fed (2.8 × 191 kcal/kg BW 0.60 ), for 7 d and every 8 h, a diet deficient in DAA nitrogen supplemented with increasing amounts of ammonia nitrogen (CP: 7.76%, 9.27%, and 10.77%; indispensable amino acid nitrogen:total nitrogen ratio: 0.71, 0.59, and 0.50 for control and low- and high-ammonia diets, respectively). The treatment sequence was based on a Latin square design with 3 consecutive periods. On the last day of each period, blood flows in the portal and hepatic veins were determined with a continuous infusion of ρ-amino hippuric acid into the mesenteric vein. Serial blood samples were taken to determine ammonia and urea nitrogen concentration. Net balances of ammonia and urea nitrogen were calculated for the PDV and liver. Results: Cumulative (8 h) ammonia nitrogen appearance in the portal vein increased ( P ≤ 0.05) with ammonia intake (433, 958, and 1629 ± 60 mg ammonia nitrogen/meal for control and low- and high-ammonia diets, respectively). The cumulative hepatic uptake of ammonia nitrogen increased ( P ≤ 0.05) with ammonia nitrogen supply. The cumulative urea nitrogen appearance in the hepatic vein tended to increase ( P ≤ 0.10) only in high-ammonia treatment (-92.5, -59.4, and 209.7 ± 92 mg urea nitrogen/meal for control and low- and high-ammonia diets, respectively) and, relative to the control diet, represented -6.0% and 11% of ammonia nitrogen intake. Conclusion: Dietary ammonia nitrogen is poorly utilized for urea

Experimental additions of aluminum sulfate and ammonium nitrate to in situ mesocosms to reduce cyanobacterial biovolume and microcystin concentration

Science.gov (United States)

Harris, Ted D.; Wilhelm, Frank M.; Graham, Jennifer L.; Loftin, Keith A.

2014-01-01

Recent studies suggest that nitrogen additions to increase the total nitrogen:total phosphorus (TN:TP) ratio may reduce cyanobacterial biovolume and microcystin concentration in reservoirs. In systems where TP is >100 μg/L, however, nitrogen additions to increase the TN:TP ratio could cause ammonia, nitrate, or nitrite toxicity to terrestrial and aquatic organisms. Reducing phosphorus via aluminum sulfate (alum) may be needed prior to nitrogen additions aimed at increasing the TN:TP ratio. We experimentally tested this sequential management approach in large in situ mesocosms (70.7 m3) to examine effects on cyanobacteria and microcystin concentration. Because alum removes nutrients and most seston from the water column, alum treatment reduced both TN and TP, leaving post-treatment TN:TP ratios similar to pre-treatment ratios. Cyanobacterial biovolume was reduced after alum addition, but the percent composition (i.e., relative) cyanobacterial abundance remained unchanged. A single ammonium nitrate (nitrogen) addition increased the TN:TP ratio 7-fold. After the TN:TP ratio was >50 (by weight), cyanobacterial biovolume and abundance were reduced, and chrysophyte and cryptophyte biovolume and abundance increased compared to the alum treatment. Microcystin was not detectable until the TN:TP ratio was <50. Although both treatments reduced cyanobacteria, only the nitrogen treatment seemed to stimulate energy flow from primary producers to zooplankton, which suggests that combining alum and nitrogen treatments may be a viable in-lake management strategy to reduce cyanobacteria and possibly microcystin concentrations in high-phosphorus systems. Additional studies are needed to define best management practices before combined alum and nitrogen additions are implemented as a reservoir management strategy.

Responses of Woody Plant Functional Traits to Nitrogen Addition: A Meta-Analysis of Leaf Economics, Gas Exchange, and Hydraulic Traits.

Science.gov (United States)

Zhang, Hongxia; Li, Weibin; Adams, Henry D; Wang, Anzhi; Wu, Jiabing; Jin, Changjie; Guan, Dexin; Yuan, Fenghui

2018-01-01

Atmospheric nitrogen (N) deposition has been found to significantly affect plant growth and physiological performance in terrestrial ecosystems. Many individual studies have investigated how N addition influences plant functional traits, however these investigations have usually been limited to a single species, and thereby do not allow derivation of general patterns or underlying mechanisms. We synthesized data from 56 papers and conducted a meta-analysis to assess the general responses of 15 variables related to leaf economics, gas exchange, and hydraulic traits to N addition among 61 woody plant species, primarily from temperate and subtropical regions. Results showed that under N addition, leaf area index (+10.3%), foliar N content (+7.3%), intrinsic water-use efficiency (+3.1%) and net photosynthetic rate (+16.1%) significantly increased, while specific leaf area, stomatal conductance, and transpiration rate did not change. For plant hydraulics, N addition significantly increased vessel diameter (+7.0%), hydraulic conductance in stems/shoots (+6.7%), and water potential corresponding to 50% loss of hydraulic conductivity ( P 50 , +21.5%; i.e., P 50 became less negative), while water potential in leaves (-6.7%) decreased (became more negative). N addition had little effect on vessel density, hydraulic conductance in leaves and roots, or water potential in stems/shoots. N addition had greater effects on gymnosperms than angiosperms and ammonium nitrate fertilization had larger effects than fertilization with urea, and high levels of N addition affected more traits than low levels. Our results demonstrate that N addition has coupled effects on both carbon and water dynamics of woody plants. Increased leaf N, likely fixed in photosynthetic enzymes and pigments leads to higher photosynthesis and water use efficiency, which may increase leaf growth, as reflected in LAI results. These changes appear to have downstream effects on hydraulic function through increases

Mechanism of improvement on strength and toughness of H13 die steel by nitrogen

International Nuclear Information System (INIS)

Li, Jing-Yuan; Chen, Yu-Lai; Huo, Jian-Hua

2015-01-01

The mechanism of nitrogen addition to AISI H13 die steel is proposed and supported using thermodynamic calculations in addition to observed changes in precipitate, microstructure, crystal structure, and macroproperties. The results indicate that the average impact toughness ak of the novel nitrogen H13 steel is maximally 17.6 J cm −2 and minimally 13.4 J cm −2 . These values result in die steel that reaches premium grade and approximate the superior grade as specified in NADCA#207-2003, additionally the hardness is improved 3–5HRC. Experimental findings indicate that the residual V(C,N) particles undissolved during nitrogen H13 steel austenitizing by quenching helps to suppress growth of original austenitic crystal grains, this in turn results in finer martensitic structures after quenching. In the subsequent tempering process all N atoms are dissolved in the solid state matrix a result of C atoms displacing N atoms in V(C,N). Solid dissolution of N atoms produces a distorted lattice of Fe matrix which results in an increase in the hardness of the steel. Additionally this displacement reaction is important for slow growth of secondary particles in nitrogen H13 steel during the tempering process which helps to increase impact toughness compared to its nitrogen-free counterpart given the same condition of heat-treatment

The reaction between barium and nitrogen in liquid sodium: resistivity studies

International Nuclear Information System (INIS)

Addison, C.C.; Creffield, G.K.; Hubberstey, P.; Pulham, R.J.

1976-01-01

The reaction of nitrogen with solutions of barium (between 0.34 and 6.89 mol % Ba) in liquid sodium at 573 K has been followed by changes in the electrical resistivity of the liquid. The capillary method has been employed, continuous sampling during reaction being achieved by electromagnetic pumping. The initial solution of nitrogen in the metal, followed by precipitation of barium and nitrogen from sodium as the nitride Ba 2 N, are reflected in the resistivity changes. The solubility of nitrogen in the alloy is a linear function of the barium concentration: S(mol % N) = x/4 (0 <= x <= 6.89 mol % Ba). This and the decrease in resistivity which invariably occurs during the solution process, provides additional information on the nature of solvation of nitrogen in solution in the liquid metal. (author)

Chitin: 'Forgotten' Source of Nitrogen: From Modern Chitin to Thermally Mature Kerogen: Lessons from Nitrogen Isotope Ratios

Science.gov (United States)

Schimmelmann, A.; Wintsch, R.P.; Lewan, M.D.; DeNiro, M.J.

1998-01-01

Chitinous biomass represents a major pool of organic nitrogen in living biota and is likely to have contributed some of the fossil organic nitrogen in kerogen. We review the nitrogen isotope biogeochemistry of chitin and present preliminary results suggesting interaction between kerogen and ammonium during thermal maturation. Modern arthropod chitin may shift its nitrogen isotope ratio by a few per mil depending on the chemical method of chitin preparation, mostly because N-containing non-amino-sugar components in chemically complex chitin cannot be removed quantitatively. Acid hydrolysis of chemically complex chitin and subsequent ion-chromatographic purification of the "deacetylated chitin-monomer" D-glucosamine (in hydrochloride form) provides a chemically well-defined, pure amino-sugar substrate for reproducible, high-precision determination of ??15N values in chitin. ??15N values of chitin exhibited a variability of about one per mil within an individual's exoskeleton. The nitrogen isotope ratio differed between old and new exoskeletons by up to 4 per mil. A strong dietary influence on the ??15N value of chitin is indicated by the observation of increasing ??15N values of chitin from marine crustaceans with increasing trophic level. Partial biodegradation of exoskeletons does not significantly influence ??15N values of remaining, chemically preserved amino sugar in chitin. Diagenesis and increasing thermal maturity of sedimentary organic matter, including chitin-derived nitrogen-rich moieties, result in humic compounds much different from chitin and may significantly change bulk ??15N values. Hydrous pyrolysis of immature source rocks at 330??C in contact with 15N-enriched NH4Cl, under conditions of artificial oil generation, demonstrates the abiogenic incorporation of inorganic nitrogen into carbon-bound nitrogen in kerogen. Not all organic nitrogen in natural, thermally mature kerogen is therefore necessarily derived from original organic matter, but may

Nitrogen deposition may enhance soil carbon storage via change of soil respiration dynamic during a spring freeze-thaw cycle period.

Science.gov (United States)

Yan, Guoyong; Xing, Yajuan; Xu, Lijian; Wang, Jianyu; Meng, Wei; Wang, Qinggui; Yu, Jinghua; Zhang, Zhi; Wang, Zhidong; Jiang, Siling; Liu, Boqi; Han, Shijie

2016-06-30

As crucial terrestrial ecosystems, temperate forests play an important role in global soil carbon dioxide flux, and this process can be sensitive to atmospheric nitrogen deposition. It is often reported that the nitrogen addition induces a change in soil carbon dioxide emission in growing season. However, the important effects of interactions between nitrogen deposition and the freeze-thaw-cycle have never been investigated. Here we show nitrogen deposition delays spikes of soil respiration and weaken soil respiration. We found the nitrogen addition, time and nitrogen addition×time exerted the negative impact on the soil respiration of spring freeze-thaw periods due to delay of spikes and inhibition of soil respiration (p nitrogen), 39% (medium-nitrogen) and 36% (high-nitrogen) compared with the control. And the decrease values of soil respiration under medium- and high-nitrogen treatments during spring freeze-thaw-cycle period in temperate forest would be approximately equivalent to 1% of global annual C emissions. Therefore, we show interactions between nitrogen deposition and freeze-thaw-cycle in temperate forest ecosystems are important to predict global carbon emissions and sequestrations. We anticipate our finding to be a starting point for more sophisticated prediction of soil respirations in temperate forests ecosystems.

Occurrence and transport of nitrogen in the Big Sunflower River, northwestern Mississippi, October 2009-June 2011

Science.gov (United States)

Barlow, Jeannie R.B.; Coupe, Richard H.

2014-01-01

The Big Sunflower River Basin, located within the Yazoo River Basin, is subject to large annual inputs of nitrogen from agriculture, atmospheric deposition, and point sources. Understanding how nutrients are transported in, and downstream from, the Big Sunflower River is key to quantifying their eutrophying effects on the Gulf. Recent results from two Spatially Referenced Regressions on Watershed attributes (SPARROW models), which include the Big Sunflower River, indicate minimal losses of nitrogen in stream reaches typical of the main channels of major river systems. If SPARROW assumptions of relatively conservative transport of nitrogen are correct and surface-water losses through the bed of the Big Sunflower River are negligible, then options for managing nutrient loads to the Gulf of Mexico may be limited. Simply put, if every pound of nitrogen entering the Delta is eventually delivered to the Gulf, then the only effective nutrient management option in the Delta is to reduce inputs. If, on the other hand, it can be shown that processes within river channels of the Mississippi Delta act to reduce the mass of nitrogen in transport, other hydrologic approaches may be designed to further limit nitrogen transport. Direct validation of existing SPARROW models for the Delta is a first step in assessing the assumptions underlying those models. In order to characterize spatial and temporal variability of nitrogen in the Big Sunflower River Basin, water samples were collected at four U.S. Geological Survey gaging stations located on the Big Sunflower River between October 1, 2009, and June 30, 2011. Nitrogen concentrations were generally highest at each site during the spring of the 2010 water year and the fall and winter of the 2011 water year. Additionally, the dominant form of nitrogen varied between sites. For example, in samples collected from the most upstream site (Clarksdale), the concentration of organic nitrogen was generally higher than the concentrations of

[Effects of reduced nitrogen application and soybean intercropping on nitrogen balance of sugarcane field].

Science.gov (United States)

Liu, Yu; Zhang, Ying; Yang, Wen-ting; Li, Zhi-xian; Guan, Ao-mei

2015-03-01

A four-year (2010-2013) field experiment was carried out to explore the effects of three planting patterns (sugarcane, soybean monoculture and sugarcane-soybean 1:2 intercropping) with two nitrogen input levels (300 and 525 kg . hm-2) on soybean nitrogen fixation, sugarcane and soybean nitrogen accumulation, and ammonia volatilization and nitrogen leaching in sugarcane field. The results showed that the soybean nitrogen fixation efficiency (NFE) of sugarcane-soybean inter-cropping was lower than that of soybean monoculture. There was no significant difference in NFE among the treatments with the two nitrogen application rates. The nitrogen application rate and inter-cropping did not remarkably affect nitrogen accumulation of sugarcane and soybean. The ammonia volatilization of the reduced nitrogen input treatment was significantly lower than that of the conventional nitrogen input treatment. Furthermore, there was no significant difference in nitrogen leaching at different nitrogen input levels and among different planting patterns. The sugarcane field nitrogen balance analysis indicated that the nitrogen application rate dominated the nitrogen budget of sugarcane field. During the four-year experiment, all treatments leaved a nitrogen surplus (from 73.10 to 400.03 kg . hm-2) , except a nitrogen deficit of 66.22 kg . hm-2 in 2011 in the treatment of sugarcane monoculture with the reduced nitrogen application. The excessive nitrogen surplus might increase the risk of nitrogen pollution in the field. In conclusion, sugarcane-soybean intercropping with reduced nitrogen application is feasible to practice in consideration of enriching the soil fertility, reducing nitrogen pollution and saving production cost in sugarcane field.

Stable Isotope Identification of Nitrogen Sources for United ...

Science.gov (United States)

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

Phytoremediation of Nitrogen as Green Chemistry for Wastewater Treatment System

Directory of Open Access Journals (Sweden)

Lennevey Kinidi

2017-01-01

Full Text Available It is noteworthy that ammoniacal nitrogen contamination in wastewater has reportedly posed a great threat to the environment. Although there are several conventional technologies being employed to remediate ammoniacal nitrogen contamination in wastewater, they are not sustainable and cost-effective. Along this line, the present study aims to highlight the significance of green chemistry characteristics of phytoremediation in nitrogen for wastewater treatment. Notably, ammoniacal nitrogen can be found in many types of sources and it brings harmful effects to the environment. Hence, the present study also reviews the phytoremediation of nitrogen and describes its green chemistry characteristics. Additionally, the different types of wastewater contaminants and their effects on phytoremediation and the phytoremediation consideration in wastewater treatment application and sustainable waste management of harvested aquatic macrophytes were reviewed. Finally, the present study explicates the future perspectives of phytoremediation. Based on the reviews, it can be concluded that green chemistry characteristics of phytoremediation in nitrogen have proved that it is sustainable and cost-effective in relation to other existing ammoniacal nitrogen remediation technologies. Therefore, it can be deduced that a cheaper and more environmental friendly ammoniacal nitrogen technology can be achieved with the utilization of phytoremediation in wastewater treatment.

The effect of vibrationally excited nitrogen on the low-latitude ionosphere

Directory of Open Access Journals (Sweden)

B. Jenkins

1997-11-01

Full Text Available The first five vibrationally excited states of molecular nitrogen have been included in the Sheffield University plasmasphere ionosphere model. Vibrationally excited molecular nitrogen reacts much more strongly with atomic oxygen ions than ground-state nitrogen; this means that more O+ ions are converted to NO+ ions, which in turn combine with the electrons to give reduced electron densities. Model calculations have been carried out to investigate the effect of including vibrationally excited molecular nitrogen on the low-latitude ionosphere. In contrast to mid-latitudes, a reduction in electron density is seen in all seasons during solar maximum, the greatest effect being at the location of the equatorial trough.

Nitrogen Cycling throughout Secondary Succession following Agricultural Disturbance in North-Central Virginia

Science.gov (United States)

Parisien, A.; Epstein, H. E.

2017-12-01

While much is known about the carbon cycle during succession that follows agricultural disturbance, less understood are the dynamics of the nitrogen cycle throughout secondary succession, and how plant-available nitrogen may or may not limit vegetation transitions and net primary productivity over time. Two chronosequences at the Blandy Experimental Farm in Boyce, north-central Virginia were examined to elucidate the complexities of the nitrogen cycle over a temporal successional gradient. Each chronosequence consists of one early, one mid, and one late secondary successional field ( 15 years, 30 years, and 100 years post agricultural abandonment, respectively). Five 10x10 m plots were established in each of the 6 fields for a total of 30 plots. Total soil nitrogen (and carbon) data were collected from soils to 30 cm depth at 10-cm intervals, and net nitrogen mineralization and nitrification were estimated using an in situ soil core with anion-cation exchange resin bag technique. Previous studies of carbon cycling at this location have indicated relatively constant soil CO2 efflux of approximately 1100 g C/m2, as well as increasing net primary production and therefore net ecosystem production, with time since abandonment. In addition, soil C and N, and the soil C:N ratio have been shown to increase from the early to late successional plots. Our current study marks the first comprehensive examination of soil nitrogen dynamics including mineralization and nitrification over a successional gradient at Blandy Farm. A thorough understanding of nitrogen dynamics during secondary succession is especially important in the southeastern United States, where a large portion of previously cultivated land has been abandoned over the past century, due to advances in farming efficiency and the move westward to more fertile soils. Much of the southeastern U.S. is now undergoing secondary succession, and quality data on the dynamics of nitrogen cycling during this procession can

Nitrogen Compounds in Radiation Chemistry

International Nuclear Information System (INIS)

Sims, H.E.; Dey, G.R.; Vaudey, C.E.; Peaucelle, C.; Boucher, J.L.; Toulhoat, N.; Bererd, N.; Koppenol, W.H.; Janata, E.; Dauvois, V.; Durand, D.; Legand, S.; Roujou, J.L.; Doizi, D.; Dannoux, A.; Lamouroux, C.

2009-01-01

Water radiolysis in presence of N 2 is probably the topic the most controversy in the field of water radiolysis. It still exists a strong discrepancy between the different reports of ammonia formation by water radiolysis in presence of N 2 and moreover in absence of oxygen there is no agreement on the formation or not of nitrogen oxide like NO 2 - and NO 3 -. These discrepancies come from multiple sources: - the complexity of the reaction mechanisms where nitrogen is involved - the experimental difficulties - and, the irradiation conditions. The aim of the workshop is to capitalize the knowledge needed to go further in simulations and understanding the problems caused (or not) by the presence of nitrogen / water in the environment of radioactive materials. Implications are evident in terms of corrosion, understanding of biological systems and atmospheric chemistry under radiation. Topics covered include experimental and theoretical approaches, application and fundamental researches: - Nitrate and Ammonia in radiation chemistry in nuclear cycle; - NOx in biological systems and atmospheric chemistry; - Formation of Nitrogen compounds in Nuclear installations; - Nitrogen in future power plant projects (Gen4, ITER...) and large particle accelerators. This document gathers the transparencies available for 7 of the presentations given at this workshop. These are: - H.E SIMS: 'Radiation Chemistry of Nitrogen Compounds in Nuclear Power Plant'; - G.R. DEY: 'Nitrogen Compounds Formation in the Radiolysis of Aqueous Solutions'; - C.E. VAUDEY et al.: 'Radiolytic corrosion of nuclear graphite studied with the dedicated gas irradiation cell of IPNL'; - J.L. BOUCHER: 'Roles and biosynthesis of NO in eukaryotes and prokaryotes'; - W.H. KOPPENOL: 'Chemistry of NOx'; - E. JANATA: 'Yield of OH in N 2 O saturated aqueous solution'; - V. DAUVOIS: 'Analytical strategy for the study of radiolysis gases'

Nitrogen studies for achieving the whole-year harvest

International Nuclear Information System (INIS)

Boven, G.D.; Danso, K.A.

1987-01-01

The IAEA activity in solving the problems related to recovery of productivity of soils subjected to erosion in tropical regions using nitrogen-fixator plants which include pasture bean crops and trees, is considered. The IAEA activity covers development of appropriate methods of changing fixed nitrogen in perennial plants, determination of practical ways of increasing nitrogen fixation and development of reliable and high-productivity systems of bean-herb pastures. The main attention is paid to methods of farming and selection. Favourable effect of forest planting on recovery and preservation of soil productivity and important role of isotopic and nuclear methods (using 15 N) in care for trees and nitrogen fixation improvement are underlined

Effects of N2O and O2 addition to nitrogen Townsend dielectric barrier discharges at atmospheric pressure on the absolute ground-state atomic nitrogen density

KAUST Repository

Es-sebbar, Et-touhami; Gherardi, Nicolas; Massines, Franç oise

2012-01-01

Absolute ground-state density of nitrogen atoms N (2p3 4S3/2) in non-equilibrium Townsend dielectric barrier discharges (TDBDs) at atmospheric pressure sustained in N2/N2O and N2/O2 gas mixtures has been measured using Two-photon absorption laser

Evaluation of certain food additives.

Science.gov (United States)

2012-01-01

This report represents the conclusions of a Joint FAO/WHO Expert Committee convened to evaluate the safety of various food additives, including flavouring agents, with a view to concluding as to safety concerns and to preparing specifications for identity and purity. The first part of the report contains a general discussion of the principles governing the toxicological evaluation of and assessment of dietary exposure to food additives, including flavouring agents. A summary follows of the Committee's evaluations of technical, toxicological and dietary exposure data for five food additives (magnesium dihydrogen diphosphate; mineral oil (medium and low viscosity) classes II and III; 3-phytase from Aspergillus niger expressed in Aspergillus niger; serine protease (chymotrypsin) from Nocardiopsis prasina expressed in Bacillus licheniformis; and serine protease (trypsin) from Fusarium oxysporum expressed in Fusarium venenatum) and 16 groups of flavouring agents (aliphatic and aromatic amines and amides; aliphatic and aromatic ethers; aliphatic hydrocarbons, alcohols, aldehydes, ketones, carboxylic acids and related esters, sulfides, disulfides and ethers containing furan substitution; aliphatic linear alpha,beta-unsaturated aldehydes, acids and related alcohols, acetals and esters; amino acids and related substances; epoxides; furfuryl alcohol and related substances; linear and branched-chain aliphatic, unsaturated, unconjugated alcohols, aldehydes, acids and related esters; miscellaneous nitrogen-containing substances; phenol and phenol derivatives; pyrazine derivatives; pyridine, pyrrole and quinoline derivatives; saturated aliphatic acyclic branched-chain primary alcohols, aldehydes and acids; simple aliphatic and aromatic sulfides and thiols; sulfur-containing heterocyclic compounds; and sulfur-substituted furan derivatives). Specifications for the following food additives were revised: ethyl cellulose, mineral oil (medium viscosity), modified starches and titanium

Atmospheric nitrogen dioxide at ambient levels stimulates growth and development of horticultural plants

International Nuclear Information System (INIS)

Adam, S.E.H.; Shigeto, J.; Sakamoto, A.; Takahashi, M.; Morikawa, H.

2008-01-01

Studies have demonstrated that ambient levels of atmospheric nitrogen dioxide (NO 2 ) can cause Nicotiana plumbaginifolia to double its biomass as well as its cell contents. This paper examined the influence of NO 2 on lettuce, sunflower, cucumber, and pumpkin plants. Plants were grown in environments supplemented with stable isotope-labelled NO 2 for approximately 6 weeks and irrigated with nitrates. Measured growth parameters included leaf number, internode number, stem length, number of flower buds, and root length. Results of the study demonstrated that the addition of NO 2 doubled the aboveground and belowground biomass of sunflowers, while only the aboveground biomass of pumpkin, cucumbers, and lettuces was doubled. Levels of carbon (C), nitrogen (N), phosphorus (P), potassium (K), calcium (Ca), and magnesium (Mg) were also doubled in the lettuce samples. A mass spectrometry analysis showed that only a small percentage of total plant N was derived from NO 2 . It was concluded that exogenous NO 2 additions function as a signal rather than as a significant nutrient source in horticultural plants. 22 refs., 2 tabs., 1 fig

Effective Biological Nitrogen Removal Treatment Processes for Domestic Wastewaters with Low C/N Ratios: A Review

DEFF Research Database (Denmark)

Sun, Sheng-Peng; Pellicer i Nàcher, Carles; Merkey, Brian

2010-01-01

with high efficiency and relative low costs. However, the removal of nitrogen from domestic wastewater with a low carbon/nitrogen (C/N) ratio can often be limited in municipal wastewater plants (WWTPs) because organic carbon is a limiting factor for denitrification. The present work reviews innovative....... They can effectively be used for nitrogen removal from low C/N domestic wastewater without external carbon addition. In addition, conventional and alternative carbon sources for enhanced biological nitrogen removal were also reviewed. We conclude that alternative carbon sources such as wine distillery...... at large scale for nitrogen removal from low C/N domestic wastewater, (2) further method logic are explored to introduce the Anammox pathway into domestic wastewater treatment, and (3) alternative carbon sources are explored and optimized for supporting the denitrification. With these efforts, cost...

Foliage nitrogen turnover: differences among nitrogen absorbed at different times by Quercus serrata saplings

Science.gov (United States)

Ueda, Miki U.; Mizumachi, Eri; Tokuchi, Naoko

2011-01-01

Background and Aims Nitrogen turnover within plants has been intensively studied to better understand nitrogen use strategies. However, differences among the nitrogen absorbed at different times are not completely understood and the fate of nitrogen absorbed during winter is largely uncharacterized. In the present study, nitrogen absorbed at different times of the year (growing season, winter and previous growing season) was traced, and the within-leaf nitrogen turnover of a temperate deciduous oak Quercus serrata was investigated. Methods The contributions of nitrogen absorbed at the three different times to leaf construction, translocation during the growing season, and the leaf-level resorption efficiency during leaf senescence were compared using 15N. Key Results Winter- and previous growing season-absorbed nitrogen significantly contributed to leaf construction, although the contribution was smaller than that of growing season-absorbed nitrogen. On the other hand, the leaf-level resorption efficiency of winter- and previous growing season-absorbed nitrogen was higher than that of growing season-absorbed nitrogen, suggesting that older nitrogen is better retained in leaves than recently absorbed nitrogen. Conclusions The results demonstrate that nitrogen turnover in leaves varies with nitrogen absorption times. These findings are important for understanding plant nitrogen use strategies and nitrogen cycles in forest ecosystems. PMID:21515608

Reduced turning frequency and delayed poultry manure addition reduces N loss from sugarcane compost

DEFF Research Database (Denmark)

Bryndum, Sofie; Muschler, R.; Nigatu, Abebe Nigussie

2017-01-01

Composting is an effective method to recycle biodegradable waste as soil amendment in smallholder farming systems. Although all essential plant nutrients are found in compost, a substantial amount of nitrogen is lost during composting. This study therefore investigated the potential of reducing N...... losses by (i) delaying the addition of nitrogen-rich substrates (i.e. poultry manure), and (ii) reducing the turning frequency during composting. Furthermore, we tested the effect of compost application method on nitrogen mineralization. Sugarcane-waste was composted for 54days with addition of poultry...... manure at the beginning (i.e. early addition) or after 21days of composting (delayed addition). The compost pile was then turned either every three or nine days. Composts were subsequently applied to soil as (i) homogeneously mixed, or (ii) stratified, and incubated for 28days to test the effect...

Analysis of nitrogen cycling in a forest stream during autumn using a 15N-tracer addition

Science.gov (United States)

Jennifer L. Tank; Judy L. Meyer; Diane M. Sanzone; Patrick J. Mulholland; Jackson R. Webster; Bruce J. Peterson; Wilfred M. Wollheim; Norman E. Leonard

2000-01-01

We added l5NH4Cl over 6 weeks to Upper Ball Creek, a second-order deciduous forest stream in the Appalachian Mountains, to follow the uptake, spiraling, and fate of nitrogen in a stream food web during autumn. A priori predictions of N flow and retention were made using a simple food web mass balance model. Values of ...

The marine nitrogen cycle: recent discoveries, uncertainties and the potential relevance of climate change

OpenAIRE

Voss, Maren; Bange, Hermann W.; Dippner, Joachim W.; Middelburg, Jack J.; Montoya, Joseph P.; Ward, Bess

2013-01-01

The ocean's nitrogen cycle is driven by complex microbial transformations, including nitrogen fixation, assimilation, nitrification, anammox and denitrification. Dinitrogen is the most abundant form of nitrogen in sea water but only accessible by nitrogen-fixing microbes. Denitrification and nitrification are both regulated by oxygen concentrations and potentially produce nitrous oxide (N2O), a climate-relevant atmospheric trace gas. The world's oceans, including the coastal areas and upwelli...

Marine nitrogen cycle

Digital Repository Service at National Institute of Oceanography (India)

Naqvi, S.W.A.

) such as the Marine nitrogen cycle The marine nitrogen cycle. ‘X’ and ‘Y’ are intra-cellular intermediates that do not accumulate in water column. (Source: Codispoti et al., 2001) Page 1 of 3Marine nitrogen cycle - Encyclopedia of Earth 11/20/2006http://www... and nitrous oxide budgets: Moving targets as we enter the anthropocene?, Sci. Mar., 65, 85-105, 2001. Page 2 of 3Marine nitrogen cycle - Encyclopedia of Earth 11/20/2006http://www.eoearth.org/article/Marine_nitrogen_cycle square6 Gruber, N.: The dynamics...

Ecological occurrence of Gluconacetobacter diazotrophicus and nitrogen-fixing Acetobacteraceae members: their possible role in plant growth promotion.

Science.gov (United States)

Saravanan, V S; Madhaiyan, M; Osborne, Jabez; Thangaraju, M; Sa, T M

2008-01-01

Gluconacetobacter diazotrophicus has a long-standing history of bacterial-plant interrelationship as a symbiotic endophyte capable of fixing atmospheric nitrogen. In low nitrogen fertilized sugarcane fields it plays a significant role and its occurrence was realised in most of the sugarcane growing countries. In this mini review, the association of G. diazotrophicus with sugarcane, other crop plants and with various hosts is discussed. The factors affecting survival in the rhizosphere and the putative soil mode of transmission are emphasized. In addition, other N(2)-fixing Acetobacteraceae members, including Gluconacetobacter azotocaptans, Gluconacetobacter johannae and Swaminathania salitolerans, occurring in coffee, corn and rice plants are also covered. Lastly, the plant-growth-promoting traits identified in this group of bacteria, including N(2) fixation, phytohormone synthesis, P and Zn solubilization and biocontrol, are analysed.

Few-layer MoS2 as nitrogen protective barrier

Science.gov (United States)

Akbali, B.; Yanilmaz, A.; Tomak, A.; Tongay, S.; Çelebi, C.; Sahin, H.

2017-10-01

We report experimental and theoretical investigations of the observed barrier behavior of few-layer MoS2 against nitrogenation. Owing to its low-strength shearing, low friction coefficient, and high lubricity, MoS2 exhibits the demeanor of a natural N-resistant coating material. Raman spectroscopy is done to determine the coating capability of MoS2 on graphene. Surface morphology of our MoS2/graphene heterostructure is characterized by using optical microscopy, scanning electron microscopy, and atomic force microscopy. In addition, density functional theory-based calculations are performed to understand the energy barrier performance of MoS2 against nitrogenation. The penetration of nitrogen atoms through a defect-free MoS2 layer is prevented by a very high vertical diffusion barrier, indicating that MoS2 can serve as a protective layer for the nitrogenation of graphene. Our experimental and theoretical results show that MoS2 material can be used both as an efficient nanocoating material and as a nanoscale mask for selective nitrogenation of graphene layer.

40 CFR 122.42 - Additional conditions applicable to specified categories of NPDES permits (applicable to State...

Science.gov (United States)

2010-07-01

... adequate notice to the Director of the following: (1) Any new introduction of pollutants into the POTW from... application; and accounting for all other additions of plant available nitrogen and phosphorus to the field...-year phosphorus application; accounting for all other additions of plant available nitrogen and...

Effects of combined application of organic and inorganic fertilizers plus nitrification inhibitor DMPP on nitrogen runoff loss in vegetable soils.

Science.gov (United States)

Yu, Qiaogang; Ma, Junwei; Zou, Ping; Lin, Hui; Sun, Wanchun; Yin, Jianzhen; Fu, Jianrong

2015-01-01

The application of nitrogen fertilizers leads to various ecological problems such as large amounts of nitrogen runoff loss causing water body eutrophication. The proposal that nitrification inhibitors could be used as nitrogen runoff loss retardants has been suggested in many countries. In this study, simulated artificial rainfall was used to illustrate the effect of the nitrification inhibitor DMPP (3,4-dimethyl pyrazole phosphate) on nitrogen loss from vegetable fields under combined organic and inorganic nitrogen fertilizer application. The results showed that during the three-time simulated artificial rainfall period, the ammonium nitrogen content in the surface runoff water collected from the DMPP application treatment increased by 1.05, 1.13, and 1.10 times compared to regular organic and inorganic combined fertilization treatment, respectively. In the organic and inorganic combined fertilization with DMPP addition treatment, the nitrate nitrogen content decreased by 38.8, 43.0, and 30.1% in the three simulated artificial rainfall runoff water, respectively. Besides, the nitrite nitrogen content decreased by 95.4, 96.7, and 94.1% in the three-time simulated artificial rainfall runoff water, respectively. A robust decline in the nitrate and nitrite nitrogen surface runoff loss could be observed in the treatments after the DMPP addition. The nitrite nitrogen in DMPP addition treatment exhibited a significant low level, which is near to the no fertilizer application treatment. Compared to only organic and inorganic combined fertilizer treatment, the total inorganic nitrogen runoff loss declined by 22.0 to 45.3% in the organic and inorganic combined fertilizers with DMPP addition treatment. Therefore, DMPP could be used as an effective nitrification inhibitor to control the soil ammonium oxidation in agriculture and decline the nitrogen runoff loss, minimizing the nitrogen transformation risk to the water body and being beneficial for the ecological environment.

Reactive nitrogen deposition to South East Asian rainforest

Science.gov (United States)

di Marco, Chiara F.; Phillips, Gavin J.; Thomas, Rick; Tang, Sim; Nemitz, Eiko; Sutton, Mark A.; Fowler, David; Lim, Sei F.

2010-05-01

The supply of reactive nitrogen (N) to global terrestrial ecosystems has doubled since the 1960s as a consequence of human activities, such as fertilizer application and production of nitrogen oxides by fossil-fuel burning. The deposition of atmospheric N species constitutes a major nutrient input to the biosphere. Tropical forests have been undergoing a radical land use change by increasing cultivation of sugar cane and oil palms and the remaining forests are increasingly affected by anthropogenic activities. Yet, quantifications of atmospheric nitrogen deposition to tropical forests, and nitrogen cycling under near-pristine and polluted conditions are rare. The OP3 project ("Oxidant and Particle Photochemical Processes above a Southeast Asian Tropical Rainforest") was conceived to study how emissions of reactive trace gases from a tropical rain forest mediate the regional scale production and processing of oxidants and particles, and to better understand the impact of these processes on local, regional and global scale atmospheric composition, chemistry and climate. As part of this study we have measured reactive, nitrogen containing trace gas (ammonia, nitric acid) and the associated aerosol components (ammonium, nitrate) at monthly time resolution using a simple filter / denuder for 16 months. These measurements were made at the Bukit Atur Global Atmospheric Watch tower near Danum Valley in the Malaysian state of Sabah, Borneo. In addition, the same compounds were measured at hourly time-resolution during an intensive measurement period, with a combination of a wet-chemistry system based on denuders and steam jet aerosol collectors and an aerosol mass spectrometer (HR-ToF-AMS), providing additional information on the temporal controls. During this period, concentrations and fluxes of NO, NO2 and N2O were also measured. The measurements are used for inferential dry deposition modelling and combined with wet deposition data from the South East Asian Acid

Effects of nitrogen applocation on yield and nitrogen accumulation in soybean

International Nuclear Information System (INIS)

Di Wei; Jin Xijun; Ma Chunmei; Dong Shoukun; Gong Zhenping; Zhang Lei

2010-01-01

Methods of sand cultre and 15 N tracing were used to study the effects of nitrogen application on yield and nitrogen accumulation in soybean variety SN 14 . The results showed as follows: accumulated nitrogen in the whole plant, petiole, pod shell and seed increased at the beginning and then decreased with the increase of nitrogen levels; Nitrogen accumulation in leaf and stem increased in 3 and 5 times for N 150 than that of N 0 , which indicated that high nitrogen levels promoted the nitrogen accumulation in leaf and stem, however compared with N 0 , nitrogen accumulation in root, Nodulation-N accumulated in the whole plant and seed of N 150 decreased by 60.3%, 74. 9% and 85.7% respectively, and Fertilizer-N harvest index of N 150 decreased, which was 19.8% lower than that of N 50 , as well as Nodulation-N harvest index 25.5% lower than that of N 50 . The nitrogen levels of soybean yield also firstly increased and then decreased; Compared with N 0 , plant height, pod height and lowest pod nodes of soybean treated with N 150 increased by 55.2%, 199.7% and 142.9% respectively, while no effects were found on node number. (authors)

Nitrogen and Oxygen Isotopic Studies of the Marine Nitrogen Cycle.

Science.gov (United States)

Casciotti, Karen L

2016-01-01

The marine nitrogen cycle is a complex web of microbially mediated reactions that control the inventory, distribution, and speciation of nitrogen in the marine environment. Because nitrogen is a major nutrient that is required by all life, its availability can control biological productivity and ecosystem structure in both surface and deep-ocean communities. Stable isotopes of nitrogen and oxygen in nitrate and nitrite have provided new insights into the rates and distributions of marine nitrogen cycle processes, especially when analyzed in combination with numerical simulations of ocean circulation and biogeochemistry. This review highlights the insights gained from dual-isotope studies applied at regional to global scales and their incorporation into oceanic biogeochemical models. These studies represent significant new advances in the use of isotopic measurements to understand the modern nitrogen cycle, with implications for the study of past ocean productivity, oxygenation, and nutrient status.

Utilization of nitrogen fixing trees

Energy Technology Data Exchange (ETDEWEB)

Brewbaker, J.L.; Beldt, R. van den; MacDicken, K.; Budowski, G.; Kass, D.C.L.; Russo, R.O.; Escalante, G.; Herrera, R.; Aranguren, J.; Arkcoll, D.B.; Doebereinger, J. (cord.)

1983-01-01

Six papers from the symposium are noted. Brewbaker, J.L., Beldt, R. van den, MacDicken, K. Fuelwood uses and properties of nitrogen-fixing trees, pp 193-204, (Refs. 15). Includes a list of 35 nitrogen-fixing trees of high fuelwood value. Budowski, G.; Kass, D.C.L.; Russo, R.O. Leguminous trees for shade, pp 205-222, (Refs. 68). Escalante, G., Herrera, R., Aranguren, J.; Nitrogen fixation in shade trees (Erythrina poeppigiana) in cocoa plantations in northern Venezuela, pp 223-230, (Refs. 13). Arkcoll, D.B.; Some leguminous trees providing useful fruits in the North of Brazil, pp 235-239, (Refs. 13). This paper deals with Parkia platycephala, Pentaclethra macroloba, Swartzia sp., Cassia leiandra, Hymenaea courbaril, dipteryz odorata, Inga edulis, I. macrophylla, and I. cinnamonea. Baggio, A.J.; Possibilities of the use of Gliricidia sepium in agroforestry systems in Brazil, pp 241-243; (Refs. 15). Seiffert, N.F.; Biological nitrogen and protein production of Leucaena cultivars grown to supplement the nutrition of ruminants, pp 245-249, (Refs. 14). Leucaena leucocephala cv. Peru, L. campina grande (L. leucocephala), and L. cunningham (L. leucocephalae) were promising for use as browse by beef cattle in central Brazil.

Impact of Temporary Nitrogen Deprivation on Tomato Leaf Phenolics

Directory of Open Access Journals (Sweden)

Hélène Gautier

2011-11-01

Full Text Available Reducing the use of pesticides represents a major challenge of modern agriculture. Plants synthesize secondary metabolites such as polyphenols that participate in the resistance to parasites. The aim of this study was to test: (1 the impact of nitrogen deficiency on tomato (Solanum lycopersicum leaf composition and more particularly on two phenolic molecules (chlorogenic acid and rutin as well as on the general plant biomass; and (2 whether this effect continued after a return to normal nitrogen nutrition. Our results showed that plants deprived of nitrogen for 10 or 19 days contained higher levels of chlorogenic acid and rutin than control plants. In addition, this difference persisted when the plants were once again cultivated on a nitrogen-rich medium. These findings offer interesting perspectives on the use of a short period of deprivation to modulate the levels of compounds of interest in a plant.

Influence of nitrogen additions on litter decomposition, nutrient dynamics, and enzymatic activity of two plant species in a peatland in Northeast China.

Science.gov (United States)

Song, Yanyu; Song, Changchun; Ren, Jiusheng; Tan, Wenwen; Jin, Shaofei; Jiang, Lei

2018-06-01

Nitrogen (N) availability affects litter decomposition and nutrient dynamics, especially in N-limited ecosystems. We investigated the response of litter decomposition to N additions in Eriophorum vaginatum and Vaccinium uliginosum peatlands. These two species dominate peatlands in Northeast China. In 2012, mesh bags containing senesced leaf litter of Eriophorum vaginatum and Vaccinium uliginosum were placed in N addition plots and sprayed monthly for two years with NH 4 NO 3 solution at dose rates of 0, 6, 12, and 24gNm -2 year -1 (CK, N1, N2 and N3, respectively). Mass loss, N and phosphorus (P) content, and enzymatic activity were measured over time as litter decomposed. In the control plots, V. uliginosum litter decomposed faster than E. vaginatum litter. N1, N2, and N3 treatments increased the mass losses of V. uliginosum litter by 6%, 9%, and 4% respectively, when compared with control. No significant influence of N additions was found on the decomposition of E. vaginatum litter. However, N and P content in E. vaginatum litter and V. uliginosum litter significantly increased with N additions. Moreover, N additions significantly promoted invertase and β-glucosidase activity in E. vaginatum and V. uliginosum litter. However, only in V. uliginosum litter was polyphenol oxidase activity significantly enhanced. Our results showed that initial litter quality and polyphenol oxidase activity influence the response of plant litter to N additions in peatland ecosystems. Increased N availability may change peatland soil N and P cycling by enhancing N and P immobilization during litter decomposition. Copyright © 2018 Elsevier B.V. All rights reserved.

The availability of mineral nitrogen in Mediterranean open steppe dominated by Stipa tenacissima L.

Directory of Open Access Journals (Sweden)

Irena Novosádová

2011-01-01

Full Text Available The area of interest is located in the Sierra de los Filabres in semi-arid steppe of the province of Almeria in Spain. The amount of water in the soil is a limiting factor and its availability affects the structure and species composition of ecosystem. On the other hand, the type of vegetation affects the water loss via evapotranspiration and thus the soil microclimate. It has a great influence on the growth and activity of soil microbial communities and hence the dynamics of decomposition of organic matter and nutrient availability. The aim of this study was to assess the intensity of microbial transformations of soil organic nitrogen and describe changes in the content of nitrogen mineral forms at different depths in the semi-arid climate soil in the Mediterranean region. Availability and movement of nitrogen was monitored by capturing the mineral nitrogen into the structures of ion exchange resin applied to the soil in three different variants (control variant, a variant with the addition of cellulose, and the variant with the addition of raw silk. Ion exchange resins have been installed into soil profile in 2008, 2009, and 2010. After the in situ exposure the ion exchange resins were removed from the soil profile and the quantity of captured mineral N was determined by distillation titration method. The availability of ammonia-nitrogen was significantly affected by the addition of different substrates mainly by the additions of the raw silk, where the availability was regularly the highest. However, the availability of ammonia-nitrogen form was generally higher than the availability of nitrate form.

Behaviour of uranium dioxide in liquid nitrogen tetraoxide

International Nuclear Information System (INIS)

Kobets, L.V.; Klavsut', G.N.; Dolgov, V.M.

1983-01-01

Interaction kinetics of uranium dioxide with liquid nitrogen tetroxide at 25-150 deg C has been studied. It is shown that in the temperature range studied NO[UO 2 (NO 3 ) 3 ] is the final product of the reaction. With the increase of specific surface of uranium dioxide and with the temperature increase the degree of oxide transformation increases. Uranium dioxide-liquid N 2 O 4 interaction proceeds in the diffusion region. Seeming activation energies and rate constants of the mentioned processes are calculated. Effect of nitrogen trioxide additions on transformation kinetics is considered

The marine nitrogen cycle: recent discoveries, uncertainties and the potential relevance of climate change

NARCIS (Netherlands)

Voss, M.; Bange, H.W.; Dippner, J.W.; Middelburg, J.J.; Montoya, J.P.; Ward, B.

2013-01-01

The ocean’s nitrogen cycle is driven by complex microbial transformations, including nitrogen fixation, assimilation, nitrification, anammox and denitrification. Dinitrogen is the most abundant form of nitrogen in sea water but only accessible by nitrogen-fixing microbes. Denitrification and

Tightening the nitrogen cycle

OpenAIRE

Christensen, B.T.

2004-01-01

The availability of nitrogen to crop plants is a universally important aspect of soil quality, and often nitrogen represents the immediate limitation to crop productivity in modern agriculture. Nitrogen is decisive for the nutritive value of plant products and plays a key role in the environmental impact of agricultural production. The fundamental doctrine of nitrogen management is to optimise the nitrogen use efficiency of both introduced and native soil nitrogen by increasing the temporal a...

Effects of policy measures implemented in Denmark on nitrogen pollution of the aquatic environment

DEFF Research Database (Denmark)

Kronvang, Brian; Andersen, Hans Estrup; Børgesen, Christen Duus

2008-01-01

Since 1985, seven national Action Plans (AP) have been implemented in Denmark to reduce nitrogen discharges from point sources and nitrogen losses from agriculture. The instruments applied include regulations on point source discharges from waste water treatment plants, area-related measures, e.g...... to delays in travel time in groundwater. Until now, the regulation has been performed on a national scale. A more regional or local approach is believed to be necessary in future to meet the demands of the EU Water Framework Directive......Since 1985, seven national Action Plans (AP) have been implemented in Denmark to reduce nitrogen discharges from point sources and nitrogen losses from agriculture. The instruments applied include regulations on point source discharges from waste water treatment plants, area-related measures, e...... indicators were defined: nitrogen discharges from point sources, nitrogen surplus in agriculture, nitrogen leaching from agricultural land and nitrogen concentrations and loads in surface waters. Since the introduction of mitigation programmes, discharges of nitrogen from point sources have been reduced...

Biome-scale nitrogen fixation strategies selected by climatic constraints on nitrogen cycle.

Science.gov (United States)

Sheffer, Efrat; Batterman, Sarah A; Levin, Simon A; Hedin, Lars O

2015-11-23

Dinitrogen fixation by plants (in symbiosis with root bacteria) is a major source of new nitrogen for land ecosystems(1). A long-standing puzzle(2) is that trees capable of nitrogen fixation are abundant in nitrogen-rich tropical forests, but absent or restricted to early successional stages in nitrogen-poor extra-tropical forests. This biome-scale pattern presents an evolutionary paradox(3), given that the physiological cost(4) of nitrogen fixation predicts the opposite pattern: fixers should be out-competed by non-fixers in nitrogen-rich conditions, but competitively superior in nitrogen-poor soils. Here we evaluate whether this paradox can be explained by the existence of different fixation strategies in tropical versus extra-tropical trees: facultative fixers (capable of downregulating fixation(5,6) by sanctioning mutualistic bacteria(7)) are common in the tropics, whereas obligate fixers (less able to downregulate fixation) dominate at higher latitudes. Using a game-theoretic approach, we assess the ecological and evolutionary conditions under which these fixation strategies emerge, and examine their dependence on climate-driven differences in the nitrogen cycle. We show that in the tropics, transient soil nitrogen deficits following disturbance and rapid tree growth favour a facultative strategy and the coexistence of fixers and non-fixers. In contrast, sustained nitrogen deficits following disturbance in extra-tropical forests favour an obligate fixation strategy, and cause fixers to be excluded in late successional stages. We conclude that biome-scale differences in the abundance of nitrogen fixers can be explained by the interaction between individual plant strategies and climatic constraints on the nitrogen cycle over evolutionary time.

Genetic Dissection of Root Morphological Traits Related to Nitrogen Use Efficiency in Brassica napus L. under Two Contrasting Nitrogen Conditions

Directory of Open Access Journals (Sweden)

Jie Wang

2017-09-01

Full Text Available As the major determinant for nutrient uptake, root system architecture (RSA has a massive impact on nitrogen use efficiency (NUE. However, little is known the molecular control of RSA as related to NUE in rapeseed. Here, a rapeseed recombinant inbred line population (BnaZNRIL was used to investigate root morphology (RM, an important component for RSA and NUE-related traits under high-nitrogen (HN and low-nitrogen (LN conditions by hydroponics. Data analysis suggested that RM-related traits, particularly root size had significantly phenotypic correlations with plant dry biomass and N uptake irrespective of N levels, but no or little correlation with N utilization efficiency (NUtE, providing the potential to identify QTLs with pleiotropy or specificity for RM- and NUE-related traits. A total of 129 QTLs (including 23 stable QTLs, which were repeatedly detected at least two environments or different N levels were identified and 83 of them were integrated into 22 pleiotropic QTL clusters. Five RM-NUE, ten RM-specific and three NUE-specific QTL clusters with same directions of additive-effect implied two NUE-improving approaches (RM-based and N utilization-based directly and provided valuable genomic regions for NUE improvement in rapeseed. Importantly, all of four major QTLs and most of stable QTLs (20 out of 23 detected here were related to RM traits under HN and/or LN levels, suggested that regulating RM to improve NUE would be more feasible than regulating N efficiency directly. These results provided the promising genomic regions for marker-assisted selection on RM-based NUE improvement in rapeseed.

Endophytic colonization of plant roots by nitrogen-fixing bacteria

International Nuclear Information System (INIS)

Cocking, Edward C.

2001-01-01

Nitrogen-fixing bacteria are able to enter into roots from the rhizosphere, particularly at the base of emerging lateral roots, between epidermal cells and through root hairs. In the rhizosphere growing root hairs play an important role in symbiotic recognition in legume crops. Nodulated legumes in endosymbiosis with rhizobia are amongst the most prominent nitrogen-fixing systems in agriculture. The inoculation of non-legumes, especially cereals, with various non-rhizobial diazotrophic bacteria has been undertaken with the expectation that they would establish themselves intercellularly within the root system, fixing nitrogen endophytic ally and providing combined nitrogen for enhanced crop production. However, in most instances bacteria colonize only the surface of the roots and remain vulnerable to competition from other rhizosphere micro-organisms, even when the nitrogen-fixing bacteria are endophytic, benefits to the plant may result from better uptake of soil nutrients rather than from endophytic nitrogen fixation. Azorhizobium caulinodans is known to enter the root system of cereals, other nonlegume crops and Arabidopsis, by intercellular invasion between epidermal cells and to internally colonize the plant intercellularly, including the xylem. This raises the possibility that xylem colonization might provide a nonnodular niche for endosymbiotic nitrogen fixation in rice, wheat, maize, sorghum and other non-legume crops. A particularly interesting, naturally occurring, non-qodular xylem colonising endophytic diazotrophic interaction with evidence for endophytic nitrogen fixation is that of Gluconacetobacter diazotrophicus in sugarcane. Could this beneficial endophytic colonization of sugarcane by G. diazotrophicus be extended to other members of the Gramineae, including the major cereals, and to other major non-legume crops of the World? (author)

Nitrogen supply of crops by biological nitrogen fixation. 2

International Nuclear Information System (INIS)

Jensen, E.S.; Andersen, A.J.; Soerensen, H.; Thomsen, J.D.

1985-02-01

In the present work the contributions from combined N-sources and symbiotic nitrogen fixation to the nitrogen supply of field-grown peas and field beans were evaluated by means of 15 N fertilizer dilution. The effect of N-fertilizer, supplied at sowing and at different stages of plant development, on nitrogen fixation, yield and protein production in peas, was studied in pot experiments. (author)

Exogenous trehalose improves growth under limiting nitrogen through upregulation of nitrogen metabolism.

Science.gov (United States)

Lin, Yingchao; Zhang, Jie; Gao, Weichang; Chen, Yi; Li, Hongxun; Lawlor, David W; Paul, Matthew J; Pan, Wenjie

2017-12-19

The trehalose (Tre) pathway has strong effects on growth and development in plants through regulation of carbon metabolism. Altering either Tre or trehalose 6-phosphate (T6P) can improve growth and productivity of plants as observed under different water availability. As yet, there are no reports of the effects of modification of Tre orT6P on plant performance under limiting nutrition. Here we report that nitrogen (N) metabolism is positively affected by exogenous application of Tre in nitrogen-deficient growing conditions. Spraying foliage of tobacco (Nicotiana tabacum) with trehalose partially alleviated symptoms of nitrogen deficiency through upregulation of nitrate and ammonia assimilation and increasing activities of nitrate reductase (NR), glycolate oxidase (GO), glutamine synthetase (GS) and glutamine oxoglutarate aminotransferase (GOGAT) with concomitant changes in ammonium (NH 4 + ) and nitrate (NO 3 - ) concentrations, glutamine and amino acids. Chlorophyll and total nitrogen content of leaves and rates of photosynthesis were increased compared to nitrogen-deficient plants without applied Tre. Total plant biomass accumulation was also higher in Tre -fed nitrogen-deficient plants, with a smaller proportion of dry weight partitioned to roots, compared to nitrogen-deficient plants without applied Tre. Consistent with higher nitrogen assimilation and growth, Tre application reduced foliar starch. Minimal effects of Tre feeding were observed on nitrogen-sufficient plants. The data show, for the first time, significant stimulatory effects of exogenous Tre on nitrogen metabolism and growth in plants growing under deficient nitrogen. Under such adverse conditions metabolism is regulated for survival rather than productivity. Application of Tre can alter this regulation towards maintenance of productive functions under low nitrogen. This has implications for considering approaches to modifying the Tre pathway for to improve crop nitrogen-use efficiency and

Effects of interstitial additions on the structure of Ti5Si3

International Nuclear Information System (INIS)

Williams, J. J.; Kramer, M. J.; Akinc, M.; Malik, S. K.

2000-01-01

Changes in the structure of Ti 5 Si 3 were measured by x-ray and neutron diffraction as carbon, nitrogen, or oxygen atoms were systematically incorporated into the lattice. Additionally, the lattice parameters and variable atomic positions of pure Ti 5 Si 3 were determined to be a=7.460 Aa, c=5.152 Aa, x Ti =0.2509, and x Si =0.6072. The measured trends in lattice parameters as carbon, nitrogen, or oxygen atoms were added to Ti 5 Si 3 showed that most of the previous studies on supposedly pure Ti 5 Si 3 were actually contaminated by these pervasive light elements. Also, oxygen and carbon additions were shown to strongly draw in the surrounding titanium atoms--evidence for bonding between these atoms. The bonding changes that occurred on addition of carbon, nitrogen, or oxygen acted to decrease the measured anisotropic properties of Ti 5 Si 3 , such as thermal expansion. (c) 2000 Materials Research Society

The nitrogen cycle.

Science.gov (United States)

Stein, Lisa Y; Klotz, Martin G

2016-02-08

Nitrogen is the fourth most abundant element in cellular biomass, and it comprises the majority of Earth's atmosphere. The interchange between inert dinitrogen gas (N2) in the extant atmosphere and 'reactive nitrogen' (those nitrogen compounds that support, or are products of, cellular metabolism and growth) is entirely controlled by microbial activities. This was not the case, however, in the primordial atmosphere, when abiotic reactions likely played a significant role in the inter-transformation of nitrogen oxides. Although such abiotic reactions are still important, the extant nitrogen cycle is driven by reductive fixation of dinitrogen and an enzyme inventory that facilitates dinitrogen-producing reactions. Prior to the advent of the Haber-Bosch process (the industrial fixation of N2 into ammonia, NH3) in 1909, nearly all of the reactive nitrogen in the biosphere was generated and recycled by microorganisms. Although the Haber-Bosch process more than quadrupled the productivity of agricultural crops, chemical fertilizers and other anthropogenic sources of fixed nitrogen now far exceed natural contributions, leading to unprecedented environmental degradation. Copyright © 2016 Elsevier Ltd. All rights reserved.

Soil and fertilizer nitrogen

International Nuclear Information System (INIS)

Winteringham, F.P.W.

1984-01-01

As a result of the intensified practices and effectively diminishing land resources per capita, increasing weights of both native soil- and added fertilizer-nitrogen will be lost to agriculture and its products, and will find their way into the environment. Soil-nitrogen levels and contingent productivity can nevertheless be maintained in the face of these losses on the basis of improved soil-N management. In some local situations nitrate levels in water for drinking purposes are likely to continue rising. In some cases agriculture and clearance practices are only one of several sources. In others they are clearly mainly responsible. In developing countries these losses represent those of a relatively increasingly costly input. This is due to the fact that industrial fertilizer nitrogen production is a particularly high energy-consuming process. In the more advanced industrialized countries they represent an addition to the problems and costs of environmental quality and health protection. The programmes, information and data reviewed here suggest that these problems can be contained by improved and extended soil and water management in agriculture on the basis of existing technology. In particular there appears to be enormous scope for the better exploitation of existing legumes both as non-legume crop alternatives or as biofertilizers which also possess more desirable C:N ratios than chemical fertilizer

Effect of nitrogen addition on superelasticity of Ti-Zr-Nb alloys

International Nuclear Information System (INIS)

Tahara, Masaki; Kim, Hee Young; Miyazaki, Shuichi; Inamura, Tomonari; Hosoda, Hideki

2008-01-01

Recently, the Ti-Zr-Nb alloys have been developed as Ni-free shape memory and superelastic alloys. In this study, the effect of Nb and nitrogen (N) contents on martensitic transformation behavior, shape memory effect and superelasticity in Ti-18Zr-(12-16)Nb-(0-1.0)N (at%) alloys were investigated using tensile tests, optical microscopy and X-ray diffraction. Shape memory effect was observed in Ti-18Zr-(12-13)Nb and Ti-18Zr-12Nb-0.5N alloys at room temperature. The superelastic behavior appeared by the increase of Nb or N content. The Ti-18Zr-(14-15)Nb, Ti-18Zr-(13-14)Nb-0.5N and Ti-18Zr-(12-14)Nb-1.0N alloys exhibited the superelasticity at room temperature. The martensitic transformation start temperature (M s ) decreased by 75 K with 1 at% increase of N content for Ti-18Zr-13Nb alloy. The critical stress for slip deformation and the stress for inducing the martensitic transformation increased with increasing N content. The superelastic recovery strain was also increased by adding N. The maximum recovery strain of 5.0% was obtained in the Ti-18Zr-14Nb-0.5N alloy. (author)

Effects of sewage sludge addition to Norway spruce seedlings on nitrogen availability and soil fauna in clear-cut areas

International Nuclear Information System (INIS)

Nieminen, Jouni K.; Räisänen, Mikko

2013-01-01

Anaerobically digested and composted sewage sludge (CSS) has been suggested to be a slow-release fertilizer in forestry and an alternative to quick-release inorganic fertilizers. The effects of CSS with or without added carbohydrate on inorganic nitrogen availability and on soil animals were tested in two Norway spruce plantations. Half of the seedlings were individually fertilized with CSS, and the rest were left as controls. Solid sucrose was added to half of the fertilized and untreated seedlings. Soil samples were taken in the autumn in the first and the second year after the treatments. CSS increased soil NH 4 –N (2100%), the proportion of soil NO 3 –N, and the N concentration of spruce needles. CSS greatly reduced the abundances of enchytraeids, tardigrades and collembolans, but increased the proportion and abundance of bacterial-feeding nematodes irrespective of carbohydrate addition. A better stabilization method needs to be developed before CSS can be used as a forest fertilizer. -- Highlights: •Spruces were fertilized with anaerobically digested and composted sewage sludge (CSS). •CSS increased soil N, proportion of NO 3 –N, and N concentration of spruce needles. •CSS reduced the abundances of enchytraeids, tardigrades and collembolans. •CSS increased the proportion and abundance of bacterial-feeding nematodes. •Sucrose did not reduce N pools or counteract negative CSS effects on soil animals. -- Composting and carbohydrate addition do not mitigate the harmful effects of anaerobically digested sewage sludge in boreal forest soil

Intracellular nitrate of marine diatoms as a driver of anaerobic nitrogen cycling in sinking aggregates

DEFF Research Database (Denmark)

Kamp, Anja; Stief, Peter; Bristow, Laura A.

2016-01-01

% was recovered as nitrite. Hence, aggregate-associated diatoms accumulate nitrate from the surrounding water and sustain complex nitrogen transformations, including loss of fixed nitrogen, in anoxic, pelagic microniches. Additionally, it may be expected that intracellular nitrate not converted before...... store nitrate intracellularly, we explored the fate of intracellular nitrate and its availability for microbial metabolism within anoxic diatom-bacteria aggregates. The ubiquitous nitrate-storing diatom Skeletonema marinoi was studied as both axenic cultures and laboratory-produced diatom......-bacteria aggregates. Stable 15N isotope incubations under dark and anoxic conditions revealed that axenic S. marinoi is able to reduce intracellular nitrate to ammonium that is immediately excreted by the cells. When exposed to a light:dark cycle and oxic conditions, S. marinoi stored nitrate intracellularly...

Long-term nitrogen addition leads to loss of species richness due to litter accumulation and soil acidification in a temperate steppe.

Science.gov (United States)

Fang, Ying; Xun, Fen; Bai, Wenming; Zhang, Wenhao; Li, Linghao

2012-01-01

Although community structure and species richness are known to respond to nitrogen fertilization dramatically, little is known about the mechanisms underlying specific species replacement and richness loss. In an experiment in semiarid temperate steppe of China, manipulative N addition with five treatments was conducted to evaluate the effect of N addition on the community structure and species richness. Species richness and biomass of community in each plot were investigated in a randomly selected quadrat. Root element, available and total phosphorus (AP, TP) in rhizospheric soil, and soil moisture, pH, AP, TP and inorganic N in the soil were measured. The relationship between species richness and the measured factors was analyzed using bivariate correlations and stepwise multiple linear regressions. The two dominant species, a shrub Artemisia frigida and a grass Stipa krylovii, responded differently to N addition such that the former was gradually replaced by the latter. S. krylovii and A. frigida had highly-branched fibrous and un-branched tap root systems, respectively. S. krylovii had higher height than A. frigida in both control and N added plots. These differences may contribute to the observed species replacement. In addition, the analysis on root element and AP contents in rhizospheric soil suggests that different calcium acquisition strategies, and phosphorus and sodium responses of the two species may account for the replacement. Species richness was significantly reduced along the five N addition levels. Our results revealed a significant relationship between species richness and soil pH, litter amount, soil moisture, AP concentration and inorganic N concentration. Our results indicate that litter accumulation and soil acidification accounted for 52.3% and 43.3% of the variation in species richness, respectively. These findings would advance our knowledge on the changes in species richness in semiarid temperate steppe of northern China under N

Nitrogen uptake and fertilizer nitrogen use efficiency of wheat under different soil water conditions

International Nuclear Information System (INIS)

Wang Baiqun; Zhang Wei; Yu Cunzu

1999-01-01

The pot experiment was conducted to study the effects of soil water regime and fertilizer nitrogen rate on the yields, nitrogen uptake and fertilizer nitrogen utilization of wheat by using 15 N tracer method. The results showed that the aboveground biomass, stem yield and grain yield increased with the increase of soil moisture in the fertilizer nitrogen treatments. All the yield increased with the increase of the fertilizer nitrogen rate in the soil water treatments. It was found that both soil water regime and fertilizer nitrogen rate significantly influenced the amount of nitrogen uptake by wheat according to the variance analysis. The amount of nitrogen uptake increased with the rise of the soil moisture in fertilizer nitrogen treatments and the amount also increased with the increase of the urea nitrogen rate in the soil water regime. Soil water regimes not only had an impact on nitrogen uptake but also had a close relationship with soil nitrogen supply and fertilizer nitrogen use efficiency. The soil A values decreased in urea treatment and increased with the rise of the soil moisture in the combination treatment of urea with pig manure. The fertilizer nitrogen use efficiency rose with the rise of the soil moisture in the same fertilizer nitrogen treatment. The fertilizer nitrogen use efficiency of the urea treatment was 13.3%, 27.9% and 32.3% in the soils with 50%, 70% and 90% of the field water capacity, respectively. The fertilizer nitrogen use efficiency in the combination treatment of urea with pig manure was 20.0%, 29.9% and 34.4% in the soils of above three levels, respectively. It was concluded that the low soil moisture restricted urea nitrogen use efficiency (UNUE) and the UNUE could be raised by combination treatment of urea with manure in the soil of enough moisture

[Effect of Elodea nuttallii-immobilized Nitrogen Cycling Bacteria on Nitrogen Removal Mechanism in an Inflow River, Gonghu Bay].

Science.gov (United States)

Han, Hua-yang; Li, Zheng-kui; Wang, Hao; Zhu, Qian

2016-04-15

Undisturbed sediment cores and surface water from Qinshui River in Gonghu Bay were collected to carry out a simulation experiment in our laboratory. The remediation effect of Elodea nuttallii-Immobilized Nitrogen Cycling Bacteria (INCB) was applied in the polluted inflow river. The denitrification rate, ANAMMOX rate and nitrogen microorganism diversity were measured by ¹⁵N isotope pairing technology and high-throughput sequencing technology based on 16S rRNA. The TN, NH₄⁺-N, NO₃⁻-N concentrations were reduced by 72.03%, 46.67% and 76.65% in the treatment with addition of Elodea nuttallii and INCB in our laboratory experiment. Meanwhile, denitrification bacteria and ANAMMOX bacteria had synergistic effect with each other. The denitrification and ANAMMOX rates were increased by 165 µmol (m² · h)⁻¹ and 269.7 µmol · (m² · h)⁻¹, respectively. The diversities of denitrification and ANAMMOX bacteria also increased in our experiment. From the level of major phylum, Proteobacteria, Planctomycetes, Acidobbacteria and Bacteroidetes all increased significantly. The results showed that the Elodea nuttallii-INCB assemblage technology could increase the bio-diversity of nitrogen cycling bacteria and promote the ability of nitrogen removal in Qinshui River.

"Cold" Fixation: Reconciliation of Nitrogen Fixation Rates and Diazotroph Assemblages in the Arctic Ocean

Science.gov (United States)

Fong, A. A.; Waite, A.; Rost, B.; Richter, K. U.

2016-02-01

Measurements of biological nitrogen fixation are typically conducted in oligotrophic subtropical and tropical marine environments where concentrations of fixed inorganic nitrogen are low. To date, only a handful of nitrogen fixation studies have been conducted in high latitude marine environments, but further investigation is needed to resolve the distribution of cold ocean diazotrophic assemblages. Nitrogen fixation rates and nifH gene distributions were measured at seven stations from 5°E to 20°E, north of 81°N in the Arctic Ocean at the onset of summer 2015. Discrete water samples in ice-covered regions were collected from the sea surface to 200 m for 15N2-tracer additions and targeted nifH gene and transcript analyses. Previous work suggests that heterotrophic bacteria dominate diazotrophic communities in the Arctic Ocean. Therefore, additional nifH gene surveys of sinking particles were conducted to test for enrichment on organic matter-rich microenvironments. Together, these measurements aim to reconcile diazotrophic activity with microbial community composition, further elucidating how nitrogen fixers could impact current concepts in polar carbon and nutrient cycling.

Tracing the evolutionary path to nitrogen-fixing crops.

Science.gov (United States)

Delaux, Pierre-Marc; Radhakrishnan, Guru; Oldroyd, Giles

2015-08-01

Nitrogen-fixing symbioses between plants and bacteria are restricted to a few plant lineages. The plant partner benefits from these associations by gaining access to the pool of atmospheric nitrogen. By contrast, other plant species, including all cereals, rely only on the scarce nitrogen present in the soil and what they can glean from associative bacteria. Global cereal yields from conventional agriculture are dependent on the application of massive levels of chemical fertilisers. Engineering nitrogen-fixing symbioses into cereal crops could in part mitigate the economic and ecological impacts caused by the overuse of fertilisers and provide better global parity in crop yields. Comparative phylogenetics and phylogenomics are powerful tools to identify genetic and genomic innovations behind key plant traits. In this review we highlight recent discoveries made using such approaches and we discuss how these approaches could be used to help direct the engineering of nitrogen-fixing symbioses into cereals. Copyright © 2015 The Authors. Published by Elsevier Ltd.. All rights reserved.

Nitrogen utilization efficiency and nitrogen nutrition of rice crops at MADA using the microplot nitrogen balance method

International Nuclear Information System (INIS)

Ahmad Nazrul Abd Wahid; Abdul Razak Ruslan; Latiffah Norddin; Hazlina Abdullah; Khairuddin Abdul Rahim

2004-01-01

Nitrogen (N) is a very important nutrient for rice crops and is a main component of protein. Nitrogen is essential in the production of plant chlorophyll and involves in vegetative and fruit growth and development processes. Nitrogen is a critical input and exert high cost in rice crop production. Nitrogen fertilizer is not fully utilised by the rice crop; some is lost due the processes of vaporization, hydrolysis, erosion, leaching and used by other plants and microorganisms. Several agronomic practices have been studied and adopted in this country with the purpose of increasing the efficiency nitrogen fertilizer utilization and thus, reducing the output cost for rice crops. The microplot nitrogen balance method is one of the methods used to determine uptake efficiency of nitrogen fertilizers by rice crops. In this research, the microplot of 1 m x 1 m squares in paddy plot were used, to ensure that sequential sampling was done at predetermined areas. Scheduled monthly sampling of soil and rice crops was conducted until the mature stage, harvest and post-harvest period. This MINT-MADA cooperative project contains the elements of information sharing on fertilizer efficiency measurement methods by using the N-15 isotopic tracer technique and the N-balance technique in soil, besides the cooperation on use of infrastructure and facilities, expertise and labour. (Author)

Improvement of nitrogen utilization and soil properties by addition of a mineral soil conditioner: mechanism and performance.

Science.gov (United States)

Yan, Xiaodan; Shi, Lin; Cai, Rumeng

2018-01-01

A mineral soil conditioner (MSC) composed of activated potash feldspar, gypsum, and calcium carbonate and containing an amount of available mineral nutrients, is shown to be effective for plant growth and acidic soil amelioration. In this study, a field test was conducted over four rice seasons by examining treatment with control check (CK), MSC, biological active carbon, and lime to investigate the nitrogen-use efficiency and mechanism of soil characteristic variations due to the desilicification and allitization of soil as well as the unrestrained use of nitrogen (N) fertilizer in recent years. Influences of MSC on the xylem sap intensity and mean rice yields were evaluated, and the soil type was also analyzed using the FactSage 6.1 Reaction, phase diagram, and Equilib modules. The results of the field trial showed that MSC application increased the xylem sap intensity and nitrogen export intensity by 37.33-39.85% and 31.40-51.20%, respectively. A significant increase (5.63-15.48%) in mean grain yields was achieved with MSC application over that with biological active carbon and lime application. The effects of MSC had a tendency to increase with time in the field experiment results, and grain yields increased after the initial application. The new formation of clay minerals exhibits a significant influence on [Formula: see text] fixation, especially for 2:1 phyllosilicates with illite, owing to the interlayers of the clay minerals. Our preliminary results showed that kaolinite, the main 1:1 phyllosilicate clay mineral in ferralsol, transformed to illite at room temperature as a consequence of the presence of H 4 SiO 4 and available K + supplied by MSC. This indicated that improving the soil quality combined with reducing N losses from soils is an efficient way to control non-point source pollution from agriculture without the risk of decreased in grain yield.

Nitrogen implantation into silicon at 700-1100 deg C

International Nuclear Information System (INIS)

Kachurin, G.A.; Tyschenko, I.E.; Popov, V.P.; Tijs, S.A.; Plotnikov, A.E.

1989-01-01

Nitrogen ions 130-140 kW potential accelerated were implanted in silicon heated up to Ti=700-1100 deg C. Densities of ion current were 1-5 mcA/cm 2 , doses did not exceed 5x10 17 cm -2 . Initial stages of nitride formation in buried layers are investigated by means of Rutherford backscattering, layer-by-layer Augerspctroscopy and electron microscopy. It is determind, that Ti growth from 700 up to 900 deg C is accompanied by essential reduction of defectiveness of silicon near-the-surface layer at nitrogen retention within the limits of the calculation profile of ion ranges. At Ti=900 deg C nitrogen is rather mobile and at ∼5x10 16 cm -2 dose it is drown to α-Si 3 N 4 crystalling extraction in R p range. Beginning from Ti ≅1000 deg C nitrogen is not retained in the furied layer and diffuses to the surface. No essenstial losses of nitrogen due to evaporation or inside diffusion are observed. It is noted, that critical Ti, when nitrogen is accumulated in the buried layer, correspond to critical temperatures, when light ions introduce essential structure distortions. Conclusion is made, that irradition-introduced distortions of structure represent centres of initiation and growth of nitride phase. At 1150 deg C additional annaling during 3 hs nitrogen, occurring outside the stable extraction, is redistributed between th surface and furied layers, sintering in narrow concentration peaks

Nitrogen assimilation in denitrifier Bacillus azotoformans LMG 9581T.

Science.gov (United States)

Sun, Yihua; De Vos, Paul; Willems, Anne

2017-12-01

Until recently, it has not been generally known that some bacteria can contain the gene inventory for both denitrification and dissimilatory nitrate (NO 3 - )/nitrite (NO 2 - ) reduction to ammonium (NH 4 + ) (DNRA). Detailed studies of these microorganisms could shed light on the differentiating environmental drivers of both processes without interference of organism-specific variation. Genome analysis of Bacillus azotoformans LMG 9581 T shows a remarkable redundancy of dissimilatory nitrogen reduction, with multiple copies of each denitrification gene as well as DNRA genes nrfAH, but a reduced capacity for nitrogen assimilation, with no nas operon nor amtB gene. Here, we explored nitrogen assimilation in detail using growth experiments in media with different organic and inorganic nitrogen sources at different concentrations. Monitoring of growth, NO 3 - NO 2 - , NH 4 + concentration and N 2 O production revealed that B. azotoformans LMG 9581 T could not grow with NH 4 + as sole nitrogen source and confirmed the hypothesis of reduced nitrogen assimilation pathways. However, NH 4 + could be assimilated and contributed up to 50% of biomass if yeast extract was also provided. NH 4 + also had a significant but concentration-dependent influence on growth rate. The mechanisms behind these observations remain to be resolved but hypotheses for this deficiency in nitrogen assimilation are discussed. In addition, in all growth conditions tested a denitrification phenotype was observed, with all supplied NO 3 - converted to nitrous oxide (N 2 O).

Improvement of phenolic antioxidants and quality characteristics of virgin olive oil with the addition of enzymes and nitrogen during olive paste processing

Energy Technology Data Exchange (ETDEWEB)

Inconomou, D.; Arapoglou, D.; Israilides, C.

2010-07-01

The evolution of phenolic compounds and their contribution to the quality characteristics in virgin olive oil during fruit processing was studied with the addition of a combination of various commercial enzymes containing pectinases, polygalacturonases, cellulase and {beta}-glucanase with or without nitrogen flush. Olive fruits (Olea europaea, L.) of the cultivar Megaritiki, at the semi black pigmentation stage of maturity, were used in a 3-phase extraction system in an experiment at industrial scale. The addition of enzymes in the olive paste during processing increased the total phenol and ortho-diphenol contents, as well as some simple phenolic compounds (3,4-DHPEA, p-HPEA) and the secoiridoid derivatives (3,4-DHPEA-EDA and 3,4-DHPEAEA) in olive oil and therefore improved its oxidative stability. Furthermore, enzyme treatment ameliorated the quality parameters of the produced olive oil (acidity and peroxide value) and their sensory attributes. The use of additional N{sub 2} flush with the enzyme treatments did not improve the quality parameters of olive oil any further; however it did not affect the concentration of individual and total sterols or most of the fatty acid composition. Consequently, olive paste treatment with enzymes not only improved the quality characteristics of olive oil and enhanced the overall organoleptic quality, but also increased the olive oil yield. (Author) 33 refs.

Nitrogenous zeolite nanomaterial and the possibility of its application in agriculture

Directory of Open Access Journals (Sweden)

G. Tsintskaladze

2017-09-01

Full Text Available New nanotechnological method is proposed to reduce the negative effects of nitrogenous fertilizers and their losses, which involves introduction of nitrogen-containing substance into the structure of natural zeolite. The obtained nanomaterials can be used as a nitrogen fertilizer, which allows the gradual transfer of nitrates into the soil and minimizing fertilization losses. It also significantly reduces groundwater contamination. Also, volatilization as well as drain losses of nitrogen are significantly reduced. Proposed zeolite nanomaterial represents a strong reserve of nitrogen compounds required for feeding the plants. Obtained nanomaterial structure is studied using chemical, X-ray diffractometric and IR spectroscopic methods. Also, nanotechnological process of enrichment and extraction of natural zeolite with ammonium nitrate is established. For proving the effectiveness of proposed nitrogenous fertilizer tests were conducted on corn crop (108 m2 where the average harvest on the recording area amounted 92.6 kg. In addition to the field test, the production test was also conducted on 1 ha where the increased corn crop reached 1.4 t/ha which is equal to 18.9%.

Quantifying benthic nitrogen fluxes in Puget Sound, Washington: a review of available data

Science.gov (United States)

Sheibley, Richard W.; Paulson, Anthony J.

2014-01-01

Understanding benthic fluxes is important for understanding the fate of materials that settle to the Puget Sound, Washington, seafloor, as well as the impact these fluxes have on the chemical composition and biogeochemical cycles of marine waters. Existing approaches used to measure benthic nitrogen flux in Puget Sound and elsewhere were reviewed and summarized, and factors for considering each approach were evaluated. Factors for selecting an appropriate approach for gathering information about benthic flux include: availability of resources, objectives of projects, and determination of which processes each approach measures. An extensive search of literature was undertaken to summarize known benthic nitrogen fluxes in Puget Sound. A total of 138 individual flux chamber measurements and 38 sets of diffusive fluxes were compiled for this study. Of the diffusive fluxes, 35 new datasets were located, and new flux calculations are presented in this report. About 65 new diffusive flux calculations are provided across all nitrogen species (nitrate, NO3-; nitrite, NO2-; ammonium, NH4+). Data analysis of this newly compiled benthic flux dataset showed that fluxes beneath deep (greater than 50 meters) water tended to be lower than those beneath shallow (less than 50 meters) water. Additionally, variability in flux at the shallow depths was greater, possibly indicating a more dynamic interaction between the benthic and pelagic environments. The overall range of bottom temperatures from studies in the Puget Sound area were small (5–16 degrees Celsius), and only NH4+ flux showed any pattern with temperature. For NH4+, flux values and variability increased at greater than about 12 degrees Celsius. Collection of additional study site metadata about environmental factors (bottom temperature, depth, sediment porosity, sediment type, and sediment organic matter) will help with development of a broader regional understanding benthic nitrogen flux in the Puget Sound.

Therapeutic journery of nitrogen mustard as alkylating anticancer agents: Historic to future perspectives.

Science.gov (United States)

Singh, Rajesh K; Kumar, Sahil; Prasad, D N; Bhardwaj, T R

2018-05-10

Cancer is considered as one of the most serious health problems today. The discovery of nitrogen mustard as an alkylating agent in 1942, opened a new era in the cancer chemotherapy. This valuable class of alkylating agent exerts its biological activity by binding to DNA, cross linking two strands, preventing DNA replication and ultimate cell death. At the molecular level, nitrogen lone pairs of nitrogen mustard generate a strained intermediate "aziridinium ion" which is very reactive towards DNA of tumor cell as well as normal cell resulting in various adverse side effects alogwith therapeutic implications. Over the last 75 years, due to its high reactivity and peripheral cytotoxicity, numerous modifications have been made in the area of nitrogen mustard to improve its efficacy as well as enhancing drug delivery specifically to tumor cells. This review mainly discusses the medicinal chemistry aspects in the development of various classes of nitrogen mustards (mechlorethamine, chlorambucil, melphalan, cyclophosphamide and steroidal based nitrogen mustards). The literature collection includes the historical and the latest developments in these areas. This comprehensive review also attempted to showcase the recent progress in the targeted delivery of nitrogen mustards that includes DNA directed nitrogen mustards, antibody directed enzyme prodrug therapy (ADEPT), gene directed enzyme prodrug therapy (GDEPT), nitrogen mustard activated by glutathione transferase, peptide based nitrogen mustards and CNS targeted nitrogen mustards. Copyright © 2018 Elsevier Masson SAS. All rights reserved.

Nitrogen fate and Transport in Diverse Agricultural Watersheds

Science.gov (United States)

Essaid, H.; McCarthy, K. A.; Baker, N. T.

2010-12-01

Nitrogen mass budgets have been estimated for ten agricultural watersheds located in a range of hydrologic settings in order to understand the factors controlling the fate of nitrogen applied at the surface. The watersheds, study areas of the Agricultural Chemical Sources, Transport and Fate study of the U.S. Geological Survey National Water Quality Assessment Program, are located in Indiana (IN), Iowa (IA), Maryland (MD), Nebraska (NE), Mississippi (MS) and Washington (WA). They range in size from 7 to 1254 km2, with four of the watersheds nested within larger watersheds. Surface water outflow (normalized to watershed area) ranged from 4 to 83 cm/yr. Crops planted include corn, soybean, small grains, rice, cotton, orchards and vegetables. “Surplus nitrogen” was determined for each watershed by subtracting estimates of crop uptake and volatilization from estimates of nitrogen input from atmospheric deposition, plant fixation, and fertilizer and manure applications for the period from 1987 to 2004. This surplus nitrogen is transported though the watershed via surface and subsurface flow paths, while simultaneously undergoing transformations (such as denitrification and in-stream processing) that result in less export of nitrogen from the watershed. Surface-water discharge and concentration data were used to estimate the export of nitrogen from the watersheds (groundwater outflow from the watersheds was minimal). Subtracting nitrogen export from surplus nitrogen provides an estimate of the net amount of nitrogen removal occurring during internal watershed transport. Watershed average nitrogen surplus ranged from 6 to 49 kg-N/ha. The more permeable and/or greater water flux watersheds (MD, NE, and WA) tended to have larger surplus nitrogen, possibly due to less crop uptake caused by greater leaching and runoff of nitrogen. Almost all of the surplus nitrogen in the low permeability (MS) and tile drained watersheds (IA, IN) was exported from the watershed with

Adding a nitrogen footprint to Colorado State University’s sustainability plan

Science.gov (United States)

Kimiecik, Jacob; Baron, Jill S.; Weinmann, Timothy; Taylor, Emily

2017-01-01

As a large land grant university with more than 32,000 students, Colorado State University has both on-campus non-agricultural and agricultural sources of nitrogen (N) released to the environment. We used the Nitrogen Footprint Tool to estimate the amount of N released from different sectors of the university for the CSU 2014 academic year. The largest on campus sources were food production, utilities (heating, cooling, electricity), and research animals. The total on-campus N footprint in 2014 was 287 metric tons. This value was equivalent to the nitrogen footprint of agricultural experiment stations and other agricultural facilities, whose nitrogen footprint was 273 metric tons. CSU has opportunities to reduce its on-campus footprint through educational programs promoting low-meat diets and commuting by bicycle or bus. There is also an opportunity to advance ideas of agricultural best management practices, including precision farming and better livestock management. This article describes the planned and ongoing efforts to educate CSU about how societal activities release nitrogen to the environment, contributing to global change. It offers personal and institutional options for taking action, which would ultimately reduce CSU’s excess reactive nitrogen loss to the environment. The N-footprint for CSU, including scenarios of possible future nitrogen reductions, is also discussed.

Nitrogen concentrations in mosses indicate the spatial distribution of atmospheric nitrogen deposition in Europe

International Nuclear Information System (INIS)

Harmens, H.; Norris, D.A.; Cooper, D.M.; Mills, G.; Steinnes, E.; Kubin, E.; Thoeni, L.; Aboal, J.R.; Alber, R.; Carballeira, A.; Coskun, M.; De Temmerman, L.; Frolova, M.; Gonzalez-Miqueo, L.

2011-01-01

In 2005/6, nearly 3000 moss samples from (semi-)natural location across 16 European countries were collected for nitrogen analysis. The lowest total nitrogen concentrations in mosses ( 2 = 0.91) linear relationship was found between the total nitrogen concentration in mosses and measured site-specific bulk nitrogen deposition rates. The total nitrogen concentrations in mosses complement deposition measurements, helping to identify areas in Europe at risk from high nitrogen deposition at a high spatial resolution. - Highlights: → Nitrogen concentrations in mosses were determined at ca. 3000 sites across Europe. → Moss concentrations were compared with EMEP modelled nitrogen deposition. → The asymptotic relationship for Europe showed saturation at ca. 15 kg N ha -1 y -1 . → Linear relationships were found with measured nitrogen deposition in some countries. → Moss concentrations complement deposition measurements at high spatial resolution. - Mosses as biomonitors of atmospheric nitrogen deposition in Europe.

Dissolved organic nitrogen recalcitrance and bioavailable nitrogen quantification for effluents from advanced nitrogen removal wastewater treatment facilities

International Nuclear Information System (INIS)

Fan, Lu; Brett, Michael T.; Jiang, Wenju; Li, Bo

2017-01-01

The objective of this study was to determine the composition of nitrogen (N) in the effluents of advanced N removal (ANR) wastewater treatment plants (WWTPs). This study also tested two different experimental protocols for determining dissolved N recalcitrance. An analysis of 15 effluent samples from five WWTPs, showed effluent concentrations and especially effluent composition varied greatly from one system to the other, with total nitrogen (TN) ranging between 1.05 and 8.10 mg L −1 . Nitrate (NO 3 − ) accounted for between 38 ± 32% of TN, and ammonium accounted for a further 29 ± 28%. All of these samples were dominated by dissolved inorganic nitrogen (DIN; NO 3 −  + NH 4 + ), and uptake experiments indicated the DIN fraction was as expected highly bioavailable. Dissolved organic N (DON) accounted for 20 ± 11% for the total dissolved N in these effluents, and uptake experiments indicated the bioavailability of this fraction varied between 27 ± 26% depending on the WWTP assessed. These results indicate near complete DIN removal should be the primary goal of ANR treatment systems. The comparison of bioavailable nitrogen (BAN) quantification protocols showed that the dissolved nitrogen uptake bioassay approach was clearly a more reliable way to determine BAN concentrations compared to the conventional cell yield protocol. Moreover, because the nitrogen uptake experiment was much more sensitive, this protocol made it easier to detect extrinsic factors (such as biological contamination or toxicity) that could affect the accuracy of these bioassays. Based on these results, we recommend the nitrogen uptake bioassay using filtered and autoclaved samples to quantify BAN concentrations. However, for effluent samples indicating toxicity, algal bioassays will not accurately quantify BAN. - Highlights: • DIN was the dominated N pool for most of the tested effluent samples. • DON bioavailability considerably varied depending on the WWTP assessed. �

Remarkable activity of nitrogen-doped hollow carbon spheres encapsulated Cu on synthesis of dimethyl carbonate: Role of effective nitrogen

Science.gov (United States)

Li, Haixia; Zhao, Jinxian; Shi, Ruina; Hao, Panpan; Liu, Shusen; Li, Zhong; Ren, Jun

2018-04-01

A critical aspect in the improvement of the catalytic performance of Cu-based catalysts for the synthesis of dimethyl carbonate (DMC) is the development of an appropriate support. In this work, nitrogen-doped hollow carbon spheres (NHCSs), with 240 nm average diameter, 17 nm shell thickness, uniform mesoporous structure and a specific surface area of 611 m2 g-1, were prepared via a two-step Stӧber method. By varying the quantity of nitrogen-containing phenols used in the preparation it has been possible to control the nitrogen content and, consequently, the sphericity of the NHCSs. It was found that perfect spheres were obtained for nitrogen contents below 5.4 wt.%. The catalysts (Cu@NHCSs) were prepared by the hydrothermal impregnation method. The catalytic activity towards DMC synthesis was notably enhanced due to the immobilization effect on Cu particles and the enhanced electron transfer effect exercised by the effective nitrogen species, including pyridinic-N and graphitic-N. When the average size of the copper nanoparticles was 7.4 nm and the nitrogen content was 4.0 wt.%, the values of space-time yield of DMC and of turnover frequency (TOF) reached 1528 mg/(g h) and 11.0 h-1, respectively. The TOF value of Cu@NHCSs was 6 times higher than non-doped Cu@Carbon (2.1 h-1). The present work introduces the potential application of nitrogen-doped carbon materials and presents a novel procedure for the preparation of catalysts for DMC synthesis.

[Effects of nitrogen and irrigation water application on yield, water and nitrogen utilization and soil nitrate nitrogen accumulation in summer cotton].

Science.gov (United States)

Si, Zhuan Yun; Gao, Yang; Shen, Xiao Jun; Liu, Hao; Gong, Xue Wen; Duan, Ai Wang

2017-12-01

A field experiment was carried out to study the effects of nitrogen and irrigation water application on growth, yield, and water and nitrogen use efficiency of summer cotton, and to develop the optimal water and nitrogen management model for suitable yield and less nitrogen loss in summer cotton field in the Huang-Huai region. Two experimental factors were arranged in a split plot design. The main plots were used for arranging nitrogen factor which consisted of five nitrogen fertilizer le-vels(0, 60, 120, 180, 240 kg·hm -2 , referred as N 0 , N 1 , N 2 , N 3 , N 4 ), and the subplots for irrigation factor which consisted of three irrigation quota levels (30, 22.5, 15 mm, referred as I 1 , I 2 , I 3 ). There were 15 treatments with three replications. Water was applied with drip irrigation system. Experimental results showed that both irrigation and nitrogen fertilization promoted cotton growth and yield obviously, but nitrogen fertilizer showed more important effects than irrigation and was the main factor of regulating growth and yield of summer cotton in the experimental region. With the increase of nitrogen fertilization rate and irrigation amount, the dry mater accumulation of reproductive organs, the above-ground biomass at the flowering-bolling stage and seed cotton yield increased gradually, reached peak values at nitrogen fertilization rate of 180 kg·hm -2 and decreased slowly with the nitrogen fertilization rate further increased. The maximum yield of 4016 kg·hm -2 was observed in the treatment of N 3 I 1 . Increasing nitrogen fertilizer amount would improve significantly total N absorption of shoots and N content of stem and leaf, but decrease nitrogen partial factor productivity. The maximum irrigation-water use efficiency of 5.40 kg·m -3 and field water use efficiency of 1.24 kg·m -3 were found in the treatments of N 3 I 3 and N 3 I 1 , respectively. With increasing nitrogen fertilization amount, soil NO 3 - -N content increased and the main soil

[Characteristics of dry matter production and nitrogen accumulation in barley genotypes with high nitrogen utilization efficiency].

Science.gov (United States)

Huang, Yi; Li, Ting-Xuan; Zhang, Xi-Zhou; Ji, Lin

2014-07-01

A pot experiment was conducted under low (125 mg x kg-1) and normal (250 mg x kg(-1)) nitrogen treatments. The nitrogen uptake and utilization efficiency of 22 barley cultivars were investigated, and the characteristics of dry matter production and nitrogen accumulation in barley were analyzed. The results showed that nitrogen uptake and utilization efficiency were different for barley under two nitrogen levels. The maximal values of grain yield, nitrogen utilization efficiency for grain and nitrogen harvest index were 2.87, 2.91 and 2.47 times as those of the lowest under the low nitrogen treatment. Grain yield and nitrogen utilization efficiency for grain and nitrogen harvest index of barley genotype with high nitrogen utilization efficiency were significantly greater than low nitrogen utilization efficiency, and the parameters of high nitrogen utilization efficiency genotype were 82.1%, 61.5% and 50.5% higher than low nitrogen utilization efficiency genotype under the low nitrogen treatment. Dry matter mass and nitrogen utilization of high nitrogen utilization efficiency was significantly higher than those of low nitrogen utilization efficiency. A peak of dry matter mass of high nitrogen utilization efficiency occurred during jointing to heading stage, while that of nitrogen accumulation appeared before jointing. Under the low nitrogen treatment, dry matter mass of DH61 and DH121+ was 34.4% and 38.3%, and nitrogen accumulation was 54. 8% and 58.0% higher than DH80, respectively. Dry matter mass and nitrogen accumulation seriously affected yield before jointing stage, and the contribution rates were 47.9% and 54.7% respectively under the low nitrogen treatment. The effect of dry matter and nitrogen accumulation on nitrogen utilization efficiency for grain was the largest during heading to mature stages, followed by sowing to jointing stages, with the contribution rate being 29.5% and 48.7%, 29.0% and 15.8%, respectively. In conclusion, barley genotype with high

Nitrogen Nutrition of Sugar Beet as Affected by Water Salinity, Proline Acid and Nitrogen Forms Using 15N Tracer Technique

International Nuclear Information System (INIS)

Abdel Aziz, H.A.

2014-01-01

A pot experiment was conducted under green house condition using sugar beet as a test crop. Saline water (sea water) was applied at different levels. i.e. fresh water, 4 and 8 dSm -1 . Labelled urea and ammonium sulphate (5% a.e.) were applied at rate of 120 kg N fed -1 . Also; proline amino acid was sprayed at rate of 25, and 50 ppm. Basal recommended doses of P and K were applied. Crop leaves and tuber yield were severely affected by sea water salinity. These parameters were improved by adding proline acid. Effect of proline acid was significantly varied according to rate of addition, water salinity levels and N forms. In this respect, the improvement of leaves and tuber was more pronounced at rate of 50 ppm proline under 8 dSm -1 salinity when plants fertilized with ammonium sulfate. Another picture was drawn with urea, where the improvement was detected at rate of 25 ppm proline, under 4dSm -1 water salinity level. Nitrogen, phosphorus, potassium and sodium uptake by leaves and tuber of sugar beet plants were significantly improved by addition of 50 ppm proline under 4 and /or 8 dSm -1 salinity levels. Nitrogen uptake was higher in tuber and fertilization with urea than those of leaves and ammonium sulfate, respectively. Other nutrients were varied according to N forms and proline levels. Nitrogen use efficiency was enhanced by spraying proline, despite of addition rates, and negatively affected by increasing salinity levels. In this regard, no big significant difference was detected between urea and ammonium sulfat

Fired products of Cr-smectite clays in nitrogen

Directory of Open Access Journals (Sweden)

C. Volzone

2004-12-01

Full Text Available The products of Cr-smectite clays heated to 1350 ° C in nitrogen were evaluated by X-ray diffraction and chemical analysis. Cr-smectite clays were prepared at room temperature by contact between smectite clays and Cr species contained in OH-Cr solutions. The Cr species were prepared using chromium nitrate solution by addition of NaOH solution with OH/Cr = 2. Products of firing in nitrogen at the high temperature were different (magnesia chromite, donathite, iron chromium oxide and picrochromite depending on the type of isomorphous substitution of the smectite structure and the amount of retained chromium.

Cyanobacterial nitrogen fixation in the ocean: Diversity, regulation and ecology

NARCIS (Netherlands)

Stal, L.J.; Zehr, J.P.; Herrero, A.; Flores, E.

2008-01-01

Nitrogen is an essential and major component of biomass. While virtually all life depends on combined forms of nitrogen that are usually limited in availability, some prokaryotes, including many groups of cyanobacteria, can use the ubiquitous atmospheric dinitrogen (N2). As photoautotrophic bacteria

Nitrogen deposition and its ecological impact in China: An overview

Energy Technology Data Exchange (ETDEWEB)

Liu Xuejun, E-mail: xuejun.13500@gmail.com [College of Resources and Environmental Sciences, China Agricultural University, Beijing 100193 (China) and Xinjiang Institute of Ecology and Geography, Chinese Academy of Sciences, Urumqi 830011 (China); Duan Lei [Department of Environmental Science and Engineering, Tsinghua University, Beijing 100084 (China); Mo Jiangming [South China Botanical Garden, Chinese Academy of Sciences, Guangzhou 510650 (China); Du Enzai [College of Urban and Environmental Sciences, Peking University, Beijing 100871 (China); Shen Jianlin [College of Resources and Environmental Sciences, China Agricultural University, Beijing 100193 (China); Lu Xiankai [South China Botanical Garden, Chinese Academy of Sciences, Guangzhou 510650 (China); Zhang Ying [College of Resources and Environmental Sciences, China Agricultural University, Beijing 100193 (China); Zhou Xiaobing [Xinjiang Institute of Ecology and Geography, Chinese Academy of Sciences, Urumqi 830011 (China); He Chune [Institute of Geographic Sciences and Natural Resources Research,Chinese Academy of Sciences, Beijing 100101 (China); Zhang Fusuo [College of Resources and Environmental Sciences, China Agricultural University, Beijing 100193 (China)

2011-10-15

Nitrogen (N) deposition is an important component in the global N cycle that has induced large impacts on the health and services of terrestrial and aquatic ecosystems worldwide. Anthropogenic reactive N (N{sub r}) emissions to the atmosphere have increased dramatically in China due to rapid agricultural, industrial and urban development. Therefore increasing N deposition in China and its ecological impacts are of great concern since the 1980s. This paper synthesizes the data from various published papers to assess the status of the anthropogenic N{sub r} emissions and N deposition as well as their impacts on different ecosystems, including empirical critical loads for different ecosystems. Research challenges and policy implications on atmospheric N pollution and deposition are also discussed. China urgently needs to establish national networks for N deposition monitoring and cross-site N addition experiments in grasslands, forests and aquatic ecosystems. Critical loads and modeling tools will be further used in N{sub r} regulation. - This paper reviews current knowledge on nitrogen deposition and its effects across China

Nitrogen deposition and its ecological impact in China: An overview

International Nuclear Information System (INIS)

Liu Xuejun; Duan Lei; Mo Jiangming; Du Enzai; Shen Jianlin; Lu Xiankai; Zhang Ying; Zhou Xiaobing; He Chune; Zhang Fusuo

2011-01-01

Nitrogen (N) deposition is an important component in the global N cycle that has induced large impacts on the health and services of terrestrial and aquatic ecosystems worldwide. Anthropogenic reactive N (N r ) emissions to the atmosphere have increased dramatically in China due to rapid agricultural, industrial and urban development. Therefore increasing N deposition in China and its ecological impacts are of great concern since the 1980s. This paper synthesizes the data from various published papers to assess the status of the anthropogenic N r emissions and N deposition as well as their impacts on different ecosystems, including empirical critical loads for different ecosystems. Research challenges and policy implications on atmospheric N pollution and deposition are also discussed. China urgently needs to establish national networks for N deposition monitoring and cross-site N addition experiments in grasslands, forests and aquatic ecosystems. Critical loads and modeling tools will be further used in N r regulation. - This paper reviews current knowledge on nitrogen deposition and its effects across China

Soil bacterial and fungal community responses to nitrogen addition across soil depth and microhabitat in an arid shrubland

Science.gov (United States)

Mueller, Rebecca C.; Belnap, Jayne; Kuske, Cheryl R.

2015-01-01

Arid shrublands are stressful environments, typified by alkaline soils low in organic matter, with biologically-limiting extremes in water availability, temperature, and UV radiation. The widely-spaced plants and interspace biological soil crusts in these regions provide soil nutrients in a localized fashion, creating a mosaic pattern of plant- or crust-associated microhabitats with distinct nutrient composition. With sporadic and limited rainfall, nutrients are primarily retained in the shallow surface soil, patterning biological activity. We examined soil bacterial and fungal community responses to simulated nitrogen (N) deposition in an arid Larrea tridentata-Ambrosia dumosa field experiment in southern Nevada, USA, using high-throughput sequencing of ribosomal RNA genes. To examine potential interactions among the N application, microhabitat and soil depth, we sampled soils associated with shrub canopies and interspace biological crusts at two soil depths (0–0.5 or 0–10 cm) across the N-amendment gradient (0, 7, and 15 kg ha−1 yr−1). We hypothesized that localized compositional differences in soil microbiota would constrain the impacts of N addition to a microhabitat distribution that would reflect highly localized geochemical conditions and microbial community composition. The richness and community composition of both bacterial and fungal communities differed significantly by microhabitat and with soil depth in each microhabitat. Only bacterial communities exhibited significant responses to the N addition. Community composition correlated with microhabitat and depth differences in soil geochemical features. Given the distinct roles of soil bacteria and fungi in major nutrient cycles, the resilience of fungi and sensitivity of bacteria to N amendments suggests that increased N input predicted for many arid ecosystems could shift nutrient cycling toward pathways driven primarily by fungal communities.

Soil carbon mineralization following biochar addition associated with external nitrogen

Directory of Open Access Journals (Sweden)

Rudong Zhao

2015-12-01

Full Text Available Biochar has been attracting increasing attention for its potentials of C sequestration and soil amendment. This study aimed to understand the effects of combining biochar with additional external N on soil C mineralization. A typical red soil (Plinthudults was treated with two biochars made from two types of plantation-tree trunks (soil-biochar treatments, and was also treated with external N (soil-biochar-N treatments. All treatments were incubated for 42 d. The CO2-C released from the treatments was detected periodically. After the incubation, soil properties such as pH, microbial biomass C (MBC, and microbial biomass N (MBN were measured. The addition of biochar with external N increased the soil pH (4.31-4.33 compared to the soil treated with external N only (4.21. This was not observed in the comparison of soil-biochar treatments (4.75-4.80 to soil only (4.74. Biochar additions (whether or not they were associated with external N increased soil MBC and MBN, but decreased CO2-C value per unit total C (added biochar C + soil C according to the model fitting. The total CO2-C released in soil-biochar treatments were enhanced compared to soil only (i.e., 3.15 vs. 2.57 mg and 3.23 vs. 2.45 mg, which was attributed to the labile C fractions in the biochars and through soil microorganism enhancement. However, there were few changes in soil C mineralization in soil-biochar-N treatments. Additionally, the potentially available C per unit total C in soil-biochar-N treatments was lower than that observed in the soil-biochar treatments. Therefore, we believe in the short term, that C mineralization in the soil can be enhanced by biochar addition, but not by adding external N concomitantly.

Reactive nitrogen in the environment and its effect on climate change

International Nuclear Information System (INIS)

Erisman, J.W.; Bleeker, A.; Galloway, J.; Seitzinger, S.; Butterbach-Bahl, K.

2011-01-01

Humans have doubled levels of reactive nitrogen in circulation, largely as a result of fertilizer application and fossil fuel burning. This massive alteration of the nitrogen cycle affects climate, food security, energy security, human health and ecosystem services. Our estimates show that nitrogen currently leads to a net-cooling effect on climate with very high uncertainty. The many complex warming and cooling interactions between nitrogen and climate need to be better assessed, taking also into account the other effects of nitrogen on human health, environment and ecosystem services. Through improved nitrogen management substantial reductions in atmospheric greenhouse gas concentrations could be generated, also allowing for other co-benefits, including improving human health and improved provision of ecosystem services, for example clean air and water, and biodiversity.

Nitrous oxide emissions from a peatbog after 13 years of experimental nitrogen deposition

Directory of Open Access Journals (Sweden)

S. R. Leeson

2017-12-01

Full Text Available Nitrogen deposition was experimentally increased on a Scottish peatbog over a period of 13 years (2002–2015. Nitrogen was applied in three forms, NH3 gas, NH4Cl solution, and NaNO3 solution, at rates ranging from 8 (ambient to 64 kg N ha−1 yr−1, and higher near the NH3 fumigation source. An automated system was used to apply the nitrogen, such that the deposition was realistic in terms of rates and high frequency of deposition events. We measured the response of nitrous oxide (N2O flux to the increased nitrogen input. Prior expectations, based on the IPCC default emission factor, were that 1 % of the added nitrogen would be emitted as N2O. In the plots treated with NH4+ and NO3− solution, no response was seen, and there was a tendency for N2O fluxes to be reduced by additional nitrogen, though this was not significant. Areas subjected to high NH3 emitted more N2O than expected, up to 8.5 % of the added nitrogen. Differences in the response are related to the impact of the nitrogen treatments on the vegetation. In the NH4+ and NO3− treatments, all the additional nitrogen is effectively immobilised in the vegetation and top 10 cm of peat. In the NH3 treatment, much of the vegetation was killed off by high doses of NH3, and the nitrogen was presumably more available to denitrifying bacteria. The design of the wet and dry experimental treatments meant that they differed in statistical power, and we are less likely to detect an effect of the NH4+ and NO3− treatments, though they avoid issues of pseudo-replication.

Nitrogen Cycling In Latin America and : Drivers, Impacts And Vulnerabilities

Science.gov (United States)

Ometto, J. P.; Bustamante, M.; Forti, M. C.; Peres, T.; Stein, A. F.; Jaramillo, V.; Perez, C.; Pinho, P. F.; Ascarrunz, N.; Austin, A.; Martinelli, L. A.

2015-12-01

Latin America is at a crossroads where a balance should be found between production of the major agricultural commodities, reasonable and planned urbanization and conservation of its natural ecosystems and associated goods and services. Most of the natural biological fixation of the globe occurs in forests of Latin America. On the other hand, Latin America has one of the highest rate of deforestation in the world, and one of the highest increases in the use of nitrogen fertilizers. A better understanding of the responses of the N cycle to human impacts will allow better conservation of biodiversity and natural resources, with an improvement in food security and more effective land use choices in biofuel development. Latin America is a unique region in multiple aspects, and particularly relevant for this proposal are the broad climatic gradient and economic patterns that include a diverse range of natural ecosystems and socio-economic development pathways. Additionally, the region is impaired by the lack of information on actual impacts of human activity on N cycling across this diverse range of ecosystems. Finally, the large expanse of tropical ecosystems and reservoirs of biodiversity juxtaposed with an intense economic incentive for development make our understanding of human impacts in this context particularly important for global change research in the region. An evaluation of current and predicted changes in climate and land use on nitrogen stocks and fluxes in the region what is being develop by the Nnet network (Nitrogen Cycling In Latin America: Drivers, Impacts And Vulnerabilities ). This presentation will bring the latest results of this integrative initiative in Latin America, focusing on the nitrogen budget associated to provision of ecosystem services and climate change.

Effect of warming and nitrogen addition on evapotranspiration and water use efficiency in a wheat-soybean/fallow rotation from 2010 to 2014

DEFF Research Database (Denmark)

Liu, Liting; Hu, Chunsheng; Olesen, Jørgen Eivind

2016-01-01

Evapotranspiration (ET) and water use efficiency (WUE) are critical indexes in water flux cycles of croplands, being affected by climate change. However, field studies addressing influence of experimental warming on ET and WUE in semi-arid cropland are highly deficient. A two-factor experiment......, including soil temperature [ambient (C) and increased average 1.5 °C (T) at 5 cm soil depth] and nitrogen fertilizer (N) [without (N0) and with 315 kg N ha−1 input (N1)], was conducted from 2010 to 2014 in North China Plain to measure ET and WUE of wheat-soybean/fallow rotation. In the N1 treatment, warming...

Replenishment and mobilization of intracellular nitrogen pools decouples wine yeast nitrogen uptake from growth

OpenAIRE

SANCHO FORNER, MARTA; Alicia Gutiérrez; BELTRAN CASELLAS, GEMMA; José Manuel Guillamon; Jonas Warringer

2016-01-01

Wine yeast capacity to take up nitrogen from the environment and catabolize it to support population growth, fermentation, and aroma production is critical to wine production. Under nitrogen restriction, yeast nitrogen uptake is believed to be intimately coupled to reproduction with nitrogen catabolite repression (NCR) suggested mediating this link. We provide a time- and strain-resolved view of nitrogen uptake, population growth, and NCR activity in wine yeasts. Nitrogen uptake was found to ...

Effectiveness of Ammonium-Nitrogen and Nitrate-Nitrogen in Irrigation Water in Paddy Rice without Topdressed Nitrogen at the Panicle Formation Stage

OpenAIRE

池田, 元輝; 渡辺, 孝賢; Ikeda, Motoki; Watanabe, Takayasu

2002-01-01

A pot experiment was conducted to evaluate the efficiency of ammonium- and nitrate- nitrogen contained in irrigation water during the reproductive growth period of paddy rice （Oryza sativa L. cv. Hinohikari） that did not receive topdressed nitrogen at the panicle formation stage. lrrigation of water containing a low level of nitrogen （7mgNL^-1） did not increase yields so much compared to topdressed nitrogen. lrrigation of water containing a high level of nitrogen （14mgNL^-1） caused substantia...

Delay in catchment nitrogen load to streams following restrictions on fertilizer application

DEFF Research Database (Denmark)

Vervloet, Lidwien S. C.; Binning, Philip John; Borgesen, Christen D.

2018-01-01

A MIKE SHE hydrological-solute transport model including nitrate reduction is employed to evaluate the delayed response in nitrogen loads in catchment streams following the implementation of nitrogen mitigation measures since the 1980s. The nitrate transport lag times between the root zone...... and the streams for the period 1950-2011 were simulated for two catchments in Denmark and compared with observational data. Results include nitrogen concentration and mass discharge to streams. By automated baseflow separation, stream discharge was separated into baseflow and drain flow components...

Background information on a multimedia nitrogen emission reduction strategy; Hintergrundpapier zu einer multimedialen Stickstoffemissionsminderungsstrategie

Energy Technology Data Exchange (ETDEWEB)

Geupel; Jering; Frey (and others)

2009-04-15

The background information report on a multimedia nitrogen reduction strategy covers the following chapters: 1. Introduction: the nitrogen cascade and the anthropogenic influence, environmental impact of increased nitrogen emissions and effects on human health. 2. Sources and balancing of anthropogenic nitrogen emissions in Germany. 3. Environmental quality targets, activity goals of environmental measures and instruments of an integrated nitrogen reduction strategy. 4. Conclusions and perspectives. The attachments include emission sources, nitrogen release and nitrogen transport in Germany; catalogue of measures and instruments according the criteria efficiency and cost-efficacy.

Atmospheric nitrogen dioxide at ambient levels stimulates growth and development of horticultural plants

Energy Technology Data Exchange (ETDEWEB)

Adam, S.E.H.; Shigeto, J. [Hiroshima Univ., Hiroshima (Japan). Dept. of Mathematical and Life Sciences; Sakamoto, A.; Takahashi, M.; Morikawa, H. [Hiroshima Univ., Hiroshima (Japan). Dept. of Mathematical and Life Sciences, Core Research for Evolutional Science and Technology

2008-02-15

Studies have demonstrated that ambient levels of atmospheric nitrogen dioxide (NO{sub 2}) can cause Nicotiana plumbaginifolia to double its biomass as well as its cell contents. This paper examined the influence of NO{sub 2} on lettuce, sunflower, cucumber, and pumpkin plants. Plants were grown in environments supplemented with stable isotope-labelled NO{sub 2} for approximately 6 weeks and irrigated with nitrates. Measured growth parameters included leaf number, internode number, stem length, number of flower buds, and root length. Results of the study demonstrated that the addition of NO{sub 2} doubled the aboveground and belowground biomass of sunflowers, while only the aboveground biomass of pumpkin, cucumbers, and lettuces was doubled. Levels of carbon (C), nitrogen (N), phosphorus (P), potassium (K), calcium (Ca), and magnesium (Mg) were also doubled in the lettuce samples. A mass spectrometry analysis showed that only a small percentage of total plant N was derived from NO{sub 2}. It was concluded that exogenous NO{sub 2} additions function as a signal rather than as a significant nutrient source in horticultural plants. 22 refs., 2 tabs., 1 fig.

Effects of nitrogen fertilization in cotton crop on Aphis gossypii Glover (Hemiptera: Aphididae) biology

International Nuclear Information System (INIS)

Barros, Ricardo; Degrande, Paulo E.; Fernandes, Marcos G.; Nogueira, Rodrigo F.

2007-01-01

The cotton aphid, Aphis gossypii Glove, is one of the pests of cotton crop and its relation with the host seem to depend on the amount of nitrogen available to the plant. The biology of A. gossypii using different cotton nitrogen fertility regimes was studied under greenhouse conditions, in Dourados, MS. A completely randomized design with nine replications in a factorial scheme (2x4x2)+1 was used. Two nitrogen sources (sulphate of ammonium and urea), four doses of nitrogen (50, 100, 150 and 200 kg ha-1), two different times of nitrogen application and one additional treatment without nitrogen were taken as factors. The nymphal phases, the pre-reproductive, reproductive and pos-reproductive periods, longevity, the life cycle and fecundity of the cotton aphid were evaluated. The doses of nitrogen influenced the cotton aphid biology in both sources and times of application, favoring its development and fecundity. (author)

Characterisation and quantification of organic phosphorus and organic nitrogen components in aquatic systems: A Review

Energy Technology Data Exchange (ETDEWEB)

Worsfold, Paul J. [School of Earth, Ocean and Environmental Sciences, University of Plymouth, Drake Circus, Plymouth PL48AA (United Kingdom)], E-mail: pworsfold@plymouth.ac.uk; Monbet, Philippe [School of Earth, Ocean and Environmental Sciences, University of Plymouth, Drake Circus, Plymouth PL48AA (United Kingdom); Water Studies Centre, School of Chemistry, Monash University, Clayton 3800, Victoria (Australia); Tappin, Alan D.; Fitzsimons, Mark F.; Stiles, David A. [School of Earth, Ocean and Environmental Sciences, University of Plymouth, Drake Circus, Plymouth PL48AA (United Kingdom); McKelvie, Ian D. [Water Studies Centre, School of Chemistry, Monash University, Clayton 3800, Victoria (Australia)

2008-08-22

This review provides a critical assessment of knowledge regarding the determination of organic phosphorus (OP) and organic nitrogen (ON) in aquatic systems, with an emphasis on biogeochemical considerations and analytical challenges. A general background on organic phosphorus and organic nitrogen precedes a discussion of sample collection, extraction, treatment/conditioning and preconcentration of organic phosphorus/nitrogen from sediments, including suspended particulate matter, and waters, including sediment porewaters. This is followed by sections on the determination of organic phosphorus/nitrogen components. Key techniques covered for organic phosphorus components are molecular spectrometry, atomic spectrometry and enzymatic methods. For nitrogen the focus is on the measurement of total organic nitrogen concentrations by carbon hydrogen nitrogen analysis and high temperature combustion, and organic nitrogen components by gas chromatography, high-performance liquid chromatography, gel electrophoresis, mass spectrometry, nuclear magnetic resonance spectrometry, X-ray techniques and enzymatic methods. Finally future trends and needs are discussed and recommendations made.

EVAPORATION: a new vapour pressure estimation methodfor organic molecules including non-additivity and intramolecular interactions

Directory of Open Access Journals (Sweden)

S. Compernolle

2011-09-01

Full Text Available We present EVAPORATION (Estimation of VApour Pressure of ORganics, Accounting for Temperature, Intramolecular, and Non-additivity effects, a method to predict (subcooled liquid pure compound vapour pressure p⁰ of organic molecules that requires only molecular structure as input. The method is applicable to zero-, mono- and polyfunctional molecules. A simple formula to describe log₁₀p⁰(T is employed, that takes into account both a wide temperature dependence and the non-additivity of functional groups. In order to match the recent data on functionalised diacids an empirical modification to the method was introduced. Contributions due to carbon skeleton, functional groups, and intramolecular interaction between groups are included. Molecules typically originating from oxidation of biogenic molecules are within the scope of this method: aldehydes, ketones, alcohols, ethers, esters, nitrates, acids, peroxides, hydroperoxides, peroxy acyl nitrates and peracids. Therefore the method is especially suited to describe compounds forming secondary organic aerosol (SOA.

Carbon amendment stimulates benthic nitrogen cycling during the bioremediation of particulate aquaculture waste

Science.gov (United States)

Robinson, Georgina; MacTavish, Thomas; Savage, Candida; Caldwell, Gary S.; Jones, Clifford L. W.; Probyn, Trevor; Eyre, Bradley D.; Stead, Selina M.

2018-03-01

The treatment of organic wastes remains one of the key sustainability challenges facing the growing global aquaculture industry. Bioremediation systems based on coupled bioturbation-microbial processing offer a promising route for waste management. We present, for the first time, a combined biogeochemical-molecular analysis of the short-term performance of one such system that is designed to receive nitrogen-rich particulate aquaculture wastes. Using sea cucumbers (Holothuria scabra) as a model bioturbator we provide evidence that adjusting the waste C : N from 5 : 1 to 20 : 1 promoted a shift in nitrogen cycling pathways towards the dissimilatory nitrate reduction to ammonium (DNRA), resulting in net NH4+ efflux from the sediment. The carbon amended treatment exhibited an overall net N2 uptake, whereas the control receiving only aquaculture waste exhibited net N2 production, suggesting that carbon supplementation enhanced nitrogen fixation. The higher NH4+ efflux and N2 uptake was further supported by meta-genome predictions that indicate that organic-carbon addition stimulated DNRA over denitrification. These findings indicate that carbon addition may potentially result in greater retention of nitrogen within the system; however, longer-term trials are necessary to determine whether this nitrogen retention is translated into improved sea cucumber biomass yields. Whether this truly constitutes a remediation process is open for debate as there remains the risk that any increased nitrogen retention may be temporary, with any subsequent release potentially raising the eutrophication risk. Longer and larger-scale trials are required before this approach may be validated with the complexities of the in-system nitrogen cycle being fully understood.

Nitrification inhibitors mitigated reactive gaseous nitrogen intensity in intensive vegetable soils from China.

Science.gov (United States)

Fan, Changhua; Li, Bo; Xiong, Zhengqin

2018-01-15

Nitrification inhibitors, a promising tool for reducing nitrous oxide (N 2 O) losses and promoting nitrogen use efficiency by slowing nitrification, have gained extensive attention worldwide. However, there have been few attempts to explore the broad responses of multiple reactive gaseous nitrogen emissions of N 2 O, nitric oxide (NO) and ammonia (NH 3 ) and vegetable yield to nitrification inhibitor applications across intensive vegetable soils in China. A greenhouse pot experiment with five consecutive vegetable crops was performed to assess the efficacies of two nitrification inhibitors, namely, nitrapyrin and dicyandiamide on reactive gaseous nitrogen emissions, vegetable yield and reactive gaseous nitrogen intensity in four typical vegetable soils representing the intensive vegetable cropping systems across mainland China: an Acrisol from Hunan Province, an Anthrosol from Shanxi Province, a Cambisol from Shandong Province and a Phaeozem from Heilongjiang Province. The results showed soil type had significant influences on reactive gaseous nitrogen intensity, with reactive gaseous nitrogen emissions and yield mainly driven by soil factors: pH, nitrate, C:N ratio, cation exchange capacity and microbial biomass carbon. The highest reactive gaseous nitrogen emissions and reactive gaseous nitrogen intensity were in Acrisol while the highest vegetable yield occurred in Phaeozem. Nitrification inhibitor applications decreased N 2 O and NO emissions by 1.8-61.0% and 0.8-79.5%, respectively, but promoted NH 3 volatilization by 3.2-44.6% across all soils. Furthermore, significant positive correlations were observed between inhibited N 2 O+NO and stimulated NH 3 emissions with nitrification inhibitor additions across all soils, indicating that reduced nitrification posed the threat of NH 3 losses. Additionally, reactive gaseous nitrogen intensity was significantly reduced in the Anthrosol and Cambisol due to the reduced reactive gaseous nitrogen emissions and increased

The carbon-nitrogen balance of the nodule and its regulation under elevated carbon dioxide concentration.

Science.gov (United States)

Libault, Marc

2014-01-01

Legumes have developed a unique way to interact with bacteria: in addition to preventing infection from pathogenic bacteria like any other plant, legumes also developed a mutualistic symbiotic relationship with one gender of soil bacteria: rhizobium. This interaction leads to the development of a new root organ, the nodule, where the differentiated bacteria fix for the plant the atmospheric dinitrogen (atmN2). In exchange, the symbiont will benefit from a permanent source of carbon compounds, products of the photosynthesis. The substantial amounts of fixed carbon dioxide dedicated to the symbiont imposed to the plant a tight regulation of the nodulation process to balance carbon and nitrogen incomes and outcomes. Climate change including the increase of the concentration of the atmospheric carbon dioxide is going to modify the rates of plant photosynthesis, the balance between nitrogen and carbon, and, as a consequence, the regulatory mechanisms of the nodulation process. This review focuses on the regulatory mechanisms controlling carbon/nitrogen balances in the context of legume nodulation and discusses how the change in atmospheric carbon dioxide concentration could affect nodulation efficiency.

Nitrogen concentrations in mosses indicate the spatial distribution of atmospheric nitrogen deposition in Europe

Energy Technology Data Exchange (ETDEWEB)

Harmens, H., E-mail: hh@ceh.ac.uk [Centre for Ecology and Hydrology, Environment Centre Wales, Deiniol Road, Bangor, Gwynedd LL57 2UW (United Kingdom); Norris, D.A., E-mail: danor@ceh.ac.uk [Centre for Ecology and Hydrology, Environment Centre Wales, Deiniol Road, Bangor, Gwynedd LL57 2UW (United Kingdom); Cooper, D.M., E-mail: cooper@ceh.ac.uk [Centre for Ecology and Hydrology, Environment Centre Wales, Deiniol Road, Bangor, Gwynedd LL57 2UW (United Kingdom); Mills, G., E-mail: gmi@ceh.ac.uk [Centre for Ecology and Hydrology, Environment Centre Wales, Deiniol Road, Bangor, Gwynedd LL57 2UW (United Kingdom); Steinnes, E., E-mail: Eiliv.Steinnes@chem.ntnu.no [Department of Chemistry, Norwegian University of Science and Technology, 7491 Trondheim (Norway); Kubin, E., E-mail: Eero.Kubin@metla.fi [Finnish Forest Research Institute, Kirkkosaarentie 7, 91500 Muhos (Finland); Thoeni, L., E-mail: lotti.thoeni@fub-ag.ch [FUB-Research Group for Environmental Monitoring, Alte Jonastrasse 83, 8640 Rapperswil (Switzerland); Aboal, J.R., E-mail: jesusramon.aboal@usc.es [University of Santiago de Compostela, Faculty of Biology, Department of Ecology, 15782 Santiago de Compostela (Spain); Alber, R., E-mail: Renate.Alber@provinz.bz.it [Environmental Agency of Bolzano, 39055 Laives (Italy); Carballeira, A., E-mail: alejo.carballeira@usc.es [University of Santiago de Compostela, Faculty of Biology, Department of Ecology, 15782 Santiago de Compostela (Spain); Coskun, M., E-mail: coskunafm@yahoo.com [Canakkale Onsekiz Mart University, Faculty of Medicine, Department of Medical Biology, 17100 Canakkale (Turkey); De Temmerman, L., E-mail: ludet@var.fgov.be [Veterinary and Agrochemical Research Centre, Tervuren (Belgium); Frolova, M., E-mail: marina.frolova@lvgma.gov.lv [Latvian Environment, Geology and Meteorology Agency, Riga (Latvia); Gonzalez-Miqueo, L., E-mail: lgonzale2@alumni.unav.es [Univ. of Navarra, Irunlarrea No 1, 31008 Pamplona (Spain)

2011-10-15

In 2005/6, nearly 3000 moss samples from (semi-)natural location across 16 European countries were collected for nitrogen analysis. The lowest total nitrogen concentrations in mosses (<0.8%) were observed in northern Finland and northern UK. The highest concentrations ({>=}1.6%) were found in parts of Belgium, France, Germany, Slovakia, Slovenia and Bulgaria. The asymptotic relationship between the nitrogen concentrations in mosses and EMEP modelled nitrogen deposition (averaged per 50 km x 50 km grid) across Europe showed less scatter when there were at least five moss sampling sites per grid. Factors potentially contributing to the scatter are discussed. In Switzerland, a strong (r{sup 2} = 0.91) linear relationship was found between the total nitrogen concentration in mosses and measured site-specific bulk nitrogen deposition rates. The total nitrogen concentrations in mosses complement deposition measurements, helping to identify areas in Europe at risk from high nitrogen deposition at a high spatial resolution. - Highlights: > Nitrogen concentrations in mosses were determined at ca. 3000 sites across Europe. > Moss concentrations were compared with EMEP modelled nitrogen deposition. > The asymptotic relationship for Europe showed saturation at ca. 15 kg N ha{sup -1} y{sup -1}. > Linear relationships were found with measured nitrogen deposition in some countries. > Moss concentrations complement deposition measurements at high spatial resolution. - Mosses as biomonitors of atmospheric nitrogen deposition in Europe.

Nitrogen solubility in the deep mantle and the origin of Earth's primordial nitrogen budget

Science.gov (United States)

Yoshioka, Takahiro; Wiedenbeck, Michael; Shcheka, Svyatoslav; Keppler, Hans

2018-04-01

The solubility of nitrogen in the major minerals of the Earth's transition zone and lower mantle (wadsleyite, ringwoodite, bridgmanite, and Ca-silicate perovskite) coexisting with a reduced, nitrogen-rich fluid phase was measured. Experiments were carried out in multi-anvil presses at 14 to 24 GPa and 1100 to 1800 °C close to the Fe-FeO buffer. Starting materials were enriched in 15N and the nitrogen concentrations in run products were measured by secondary ion mass spectrometry. Observed nitrogen (15N) solubilities in wadsleyite and ringwoodite typically range from 10 to 250 μg/g and strongly increase with temperature. Nitrogen solubility in bridgmanite is about 20 μg/g, while Ca-silicate perovskite incorporates about 30 μg/g under comparable conditions. Partition coefficients of nitrogen derived from coexisting phases are DNwadsleyite/olivine = 5.1 ± 2.1, DNringwoodite/wadsleyite = 0.49 ± 0.29, and DNbridgmanite/ringwoodite = 0.24 (+ 0.30 / - 0.19). Nitrogen solubility in the solid, iron-rich metal phase coexisting with the silicates was also measured and reached a maximum of nearly 1 wt.% 15N at 23 GPa and 1400 °C. These data yield a partition coefficient of nitrogen between iron metal and bridgmanite of DNmetal/bridgmanite ∼ 98, implying that in a lower mantle containing about 1% of iron metal, about half of the nitrogen still resides in the silicates. The high nitrogen solubility in wadsleyite and ringwoodite may be responsible for the low nitrogen concentrations often observed in ultradeep diamonds from the transition zone. Overall, the solubility data suggest that the transition zone and the lower mantle have the capacity to store at least 33 times the mass of nitrogen presently residing in the atmosphere. By combining the nitrogen solubility data in minerals with data on nitrogen solubility in silicate melts, mineral/melt partition coefficients of nitrogen can be estimated, from which the behavior of nitrogen during magma ocean crystallization can

Performance of phosphogypsum and calcium magnesium phosphate fertilizer for nitrogen conservation in pig manure composting.

Science.gov (United States)

Li, Yun; Luo, Wenhai; Li, Guoxue; Wang, Kun; Gong, Xiaoyan

2018-02-01

This study investigated the performance of phosphogypsum and calcium magnesium phosphate fertilizer for nitrogen conservation during pig manure composting with cornstalk as the bulking agent. Results show that phosphogypsum increased nitrous oxide (N 2 O) emission, but significantly reduced ammonia (NH 3 ) emission and thus enhanced the mineral and total nitrogen (TN) contents in compost. Although N 2 O emission could be reduced by adding calcium magnesium phosphate fertilizer, NH 3 emission was considerably increased, resulting in an increase in TN loss during composting. By blending these two additives, both NH 3 and N 2 O emissions could be mitigated, achieving effective nitrogen conservation in composting. More importantly, with the addition of 20% TN of the mixed composting materials, these two additives could synergistically improve the compost maturity and quality. Copyright © 2017 Elsevier Ltd. All rights reserved.

Effect of organic matter application and water regimes on the transformation of fertilizer nitrogen in a Philippine soil

International Nuclear Information System (INIS)

Yoshida, Tomio; Padre, B.C. Jr.

1975-01-01

Greenhouse experiments using the tracer technique showed that about 20 per cent of the fertilizer nitrogen added as basal to the Maahas clay soil was immobilized in submerged soils to which no organic material was added. The addition of organic matter to the soil increases the amount of nitrogen immobilized and the magnitude depends on the carbon to nitrogen ratio of the materials added. More fertilizer nitrogen was immobilized in the soils under upland and alternate wet-and-dry conditions than under submerged soil conditions. The uptake of fertilizer nitrogen by rice plants growing under submerged soil conditions ceased at the vegetative stage of growth because only a small amount of available nitrogen remains in the soil at this time, but the rice plant continued to absorb gradually untagged nitrogen from the soil throughout the reproductive stages of growth. Losses of fertilizer nitrogen were great under the alternate wet-and-dry conditions (submerged-upland). The loss of nitrogen from the soil-plant system was reduced by the addition of rice straw, which also reduced the uptake of fertilizer nitrogen but not the total dry matter production under the experimental conditions. Fertilizer nitrogen immobilized during the first crop remained mostly in the soil throughout the full period of the second crop. The total nitrogen uptake by rice plants was not affected by the soil moisture tension under the upland conditions used in the study but the movement of nitrogen from the leaves to the panicles during the reproductive stage seemed to decrease as the soil moisture tension increased. (auth.)

The use of nitrogen to improve the corrosion resistance of FeCrNiMo alloys for the chemical process industries

Energy Technology Data Exchange (ETDEWEB)

Kearns, J.R.; Deverell, H.E.

1987-06-01

The addition of 0.1 to 0.25 wt% nitrogen to austenitic alloys has been shown to enhance resistance to localized corrosion in oxidizing chloride and reducing acid solutions. Further tests of FeCrNiMo alloys assess the effects of nitrogen additions on: mechanical properties, chloride and caustic stress corrosion cracking resistance, passivation characteristics, and general corrosion rates in various acid, alkali, and salt solutions pertinent to the chemical process industries. The precipitation of chromium-rich secondary phases was retarded by solid solution additions of 0.1 to 0.25 wt% nitrogen. The corrosion resistance of FeCrNiMoN alloys in the welded condition was improved by using shield-gas mixtures of argon and 2.5 to 5.0 wt% nitrogen.

Determination of oxygen and nitrogen in coal by instrumental neutron activation analysis

International Nuclear Information System (INIS)

Hamrin, C.E. Jr.; Johannes, A.H.; James, W.D. Jr.; Sun, G.H.; Ehmann, W.D.

1979-01-01

The purpose of this study was to measure oxygen and nitrogen in coals using instrumental neutron activation analysis. For six U.S. coals total oxygen ranged from 9.4 to 28.7% and total nitrogen varied from 0.72 to 1.61%. To obtain values of organic oxygen and nitrogen either a low-temperature-ashing (LTA) method or an acid-treatment (AT) method was suitable for bituminous coals. The mean difference of the experimentally determined values (Osub(dmmf))sub(LTA) - (Osub(dmmf))sub(AT) = -0.82, s = 0.51, [dmmf = dry, mineral-matter-free basis], was found to be statistically significant at the 95% confidence level, but the comparable difference for nitrogen was not. By the LTA method oxygen and nitrogen on the dmmf basis for bituminous coals showed no statistically significant difference with calculated dmmf values. Nitrogen was detected in all the LTAs varying from 0.38 to 1.67%. Formation of insoluble CaF 2 in the acid-treatment method caused an interference in the nitrogen determination due to the 19 F (n, 2n) 18 F reaction but was correctable. In addition, recoil proton reactions on C and O leading to the formation of 13 N must be accounted for in all nitrogen determinations in the coal matrix. (author)

Nitrate and Nitrogen Oxides: Sources, Health Effects and Their Remediation.

Science.gov (United States)

Hakeem, Khalid Rehman; Sabir, Muhammad; Ozturk, Munir; Akhtar, Mohd Sayeed; Ibrahim, Faridah Hanum

Increased use of nitrogenous (N) fertilizers in agriculture has significantly altered the global N-cycle because they release nitrogenous gases of environmental concerns. The emission of nitrous oxide (N 2 O) contributes to the global greenhouse gas accumulation and the stratospheric ozone depletion. In addition, it causes nitrate leaching problem deteriorating ground water quality. The nitrate toxicity has been reported in a number of studies showing the health hazards like methemoglobinemia in infants and is a potent cause of cancer. Despite these evident negative environmental as well as health impacts, consumption of N fertilizer cannot be reduced in view of the food security for the teeming growing world population. Various agronomic and genetic modifications have been practiced to tackle this problem. Some agronomic techniques adopted include split application of N, use of slow-release fertilizers, nitrification inhibitors and encouraging the use of organic manure over chemical fertilizers. As a matter of fact, the use of chemical means to remediate nitrate from the environment is very difficult and costly. Particularly, removal of nitrate from water is difficult task because it is chemically non-reactive in dilute aqueous solutions. Hence, the use of biological means for nitrate remediation offers a promising strategy to minimize the ill effects of nitrates and nitrites. One of the important goals to reduce N-fertilizer application can be effectively achieved by choosing N-efficient genotypes. This will ensure the optimum uptake of applied N in a balanced manner and exploring the molecular mechanisms for their uptake as well as metabolism in assimilatory pathways. The objectives of this paper are to evaluate the interrelations which exist in the terrestrial ecosystems between the plant type and characteristics of nutrient uptake and analyze the global consumption and demand for fertilizer nitrogen in relation to cereal production, evaluate the various

4H-SiC surface energy tuning by nitrogen up-take

Energy Technology Data Exchange (ETDEWEB)

Pitthan, E., E-mail: eduardo.pitthan@ufrgs.br [Institute for Advanced Materials, Devices and Nanotechnology, Rutgers University, Piscataway, NJ 08854 (United States); PGMICRO, UFRGS, 91509-900, Porto Alegre, RS (Brazil); Amarasinghe, V.P. [Institute for Advanced Materials, Devices and Nanotechnology, Rutgers University, Piscataway, NJ 08854 (United States); Xu, C.; Gustafsson, T. [Institute for Advanced Materials, Devices and Nanotechnology, Rutgers University, Piscataway, NJ 08854 (United States); Department of Physics and Astronomy, Rutgers University, Piscataway, NJ 08854 (United States); Stedile, F.C. [PGMICRO, UFRGS, 91509-900, Porto Alegre, RS (Brazil); Instituto de Química, UFRGS, 91509-900, Porto Alegre, RS (Brazil); Feldman, L.C. [Institute for Advanced Materials, Devices and Nanotechnology, Rutgers University, Piscataway, NJ 08854 (United States); Department of Physics and Astronomy, Rutgers University, Piscataway, NJ 08854 (United States)

2017-04-30

Highlights: • Wettability modification of 4H-SiC as a function of nitrogen adsorption is reported. • SiC surface energy was significantly reduced as nitrogen was incorporated. • Modifications obtained were proved to be inert to etching and stable against time. • Variable control of SiC surface provides new opportunities for biomedical applications. - Abstract: Surface energy modification and surface wettability of 4H silicon carbide (0001) as a function of nitrogen adsorption is reported. The surface wettability is shown to go from primarily hydrophilic to hydrophobic and the surface energy was significantly reduced with increasing nitrogen incorporation. These changes are investigated by x-ray photoelectron spectroscopy and contact angle measurements. The surface energy was quantitatively determined by the Fowkes model and interpreted primarily in terms of the variation of the surface chemistry with nitrogen coverage. Variable control of SiC surface energies with a simple and controllable atomic additive such as nitrogen that is inert to etching, stable against time, and also effective in electrical passivation, can provide new opportunities for SiC biomedical applications, where surface wetting plays an important role in the interaction with the biological interfaces.

Improved Eco-Friendly Recombinant Anabaena sp. Strain PCC7120 with Enhanced Nitrogen Biofertilizer Potential▿

Science.gov (United States)

Chaurasia, Akhilesh Kumar; Apte, Shree Kumar

2011-01-01

Photosynthetic, nitrogen-fixing Anabaena strains are native to tropical paddy fields and contribute to the carbon and nitrogen economy of such soils. Genetic engineering was employed to improve the nitrogen biofertilizer potential of Anabaena sp. strain PCC7120. Constitutive enhanced expression of an additional integrated copy of the hetR gene from a light-inducible promoter elevated HetR protein expression and enhanced functional heterocyst frequency in the recombinant strain. The recombinant strain displayed consistently higher nitrogenase activity than the wild-type strain and appeared to be in homeostasis with compatible modulation of photosynthesis and respiration. The enhanced combined nitrogen availability from the recombinant strain positively catered to the nitrogen demand of rice seedlings in short-term hydroponic experiments and supported better growth. The engineered strain is stable, eco-friendly, and useful for environmental application as nitrogen biofertilizer in paddy fields. PMID:21057013

Improved eco-friendly recombinant Anabaena sp. strain PCC7120 with enhanced nitrogen biofertilizer potential.

Science.gov (United States)

Chaurasia, Akhilesh Kumar; Apte, Shree Kumar

2011-01-01

Photosynthetic, nitrogen-fixing Anabaena strains are native to tropical paddy fields and contribute to the carbon and nitrogen economy of such soils. Genetic engineering was employed to improve the nitrogen biofertilizer potential of Anabaena sp. strain PCC7120. Constitutive enhanced expression of an additional integrated copy of the hetR gene from a light-inducible promoter elevated HetR protein expression and enhanced functional heterocyst frequency in the recombinant strain. The recombinant strain displayed consistently higher nitrogenase activity than the wild-type strain and appeared to be in homeostasis with compatible modulation of photosynthesis and respiration. The enhanced combined nitrogen availability from the recombinant strain positively catered to the nitrogen demand of rice seedlings in short-term hydroponic experiments and supported better growth. The engineered strain is stable, eco-friendly, and useful for environmental application as nitrogen biofertilizer in paddy fields.

Climate change affects key nitrogen-fixing bacterial populations on coral reefs

NARCIS (Netherlands)

Santos, Henrique F.; Carmo, Flavia L.; Duarte, Gustavo; Dini-Andreote, Francisco; Castro, Clovis B.; Rosado, Alexandre S.; van Elsas, Jan Dirk; Peixoto, Raquel S.

2014-01-01

Coral reefs are at serious risk due to events associated with global climate change. Elevated ocean temperatures have unpredictable consequences for the ocean's biogeochemical cycles. The nitrogen cycle is driven by complex microbial transformations, including nitrogen fixation. This study

Climate change affects key nitrogen-fixing bacterial populations on coral reefs

NARCIS (Netherlands)

Santos, Henrique F.; Carmo, Flavia L.; Duarte, Gustavo; Dini-Andreote, Francisco; Castro, Clovis B.; Rosado, Alexandre S.; van Elsas, Jan Dirk; Peixoto, Raquel S.

Coral reefs are at serious risk due to events associated with global climate change. Elevated ocean temperatures have unpredictable consequences for the ocean's biogeochemical cycles. The nitrogen cycle is driven by complex microbial transformations, including nitrogen fixation. This study

Production of polyhydroxybutyrate and alginate from glycerol by Azotobacter vinelandii under nitrogen-free conditions.

Science.gov (United States)

Yoneyama, Fuminori; Yamamoto, Mayumi; Hashimoto, Wataru; Murata, Kousaku

2015-01-01

Glycerol is an interesting feedstock for biomaterials such as biofuels and bioplastics because of its abundance as a by-product during biodiesel production. Here we demonstrate glycerol metabolism in the nitrogen-fixing species Azotobacter vinelandii through metabolomics and nitrogen-free bacterial production of biopolymers, such as poly-d-3-hydroxybutyrate (PHB) and alginate, from glycerol. Glycerol-3-phosphate was accumulated in A. vinelandii cells grown on glycerol to the exponential phase, and its level drastically decreased in the cells grown to the stationary growth phase. A. vinelandii also overexpressed the glycerol-3-phosphate dehydrogenase gene when it was grown on glycerol. These results indicate that glycerol was first converted to glycerol-3-phosphate by glycerol kinase. Other molecules with industrial interests, such as lactic acid and amino acids including γ-aminobutyric acid, have also been accumulated in the bacterial cells grown on glycerol. Transmission electron microscopy revealed that glycerol-grown A. vinelandii stored PHB within the cells. The PHB production level reached 33% per dry cell weight in nitrogen-free glycerol medium. When grown on glycerol, alginate-overproducing mutants generated through chemical mutagenesis produced 2-fold the amount of alginate from glycerol than the parental wild-type strain. To the best of our knowledge, this is the first report on bacterial production of biopolymers from glycerol without addition of any nitrogen source.

Coordinated regulation of nitrogen supply mode and initial cell density for energy storage compounds production with economized nitrogen utilization in a marine microalga Isochrysis zhangjiangensis.

Science.gov (United States)

Chi, Lei; Yao, Changhong; Cao, Xupeng; Xue, Song

2016-01-01

Lipids and carbohydrates are main energy storage compounds (ESC) of microalgae under stressed conditions and they are potential feedstock for biofuel production. Yet, the sustainable and commercially successful production of ESC in microalgae needs to consider nitrogen utilization efficiency. Here the impact of different initial cell densities (ICDs) on ESC accumulation in Isochrysis zhangjiangensis under two nitrogen supply modes (an initially equal concentration of nitrogen per-cell in the medium (N1) and an equal total concentration of nitrogen in the culture system (N2)) were investigated. The results demonstrated that the highest ESC yield (1.36gL(-1)) at N1, which included a maximal nitrogen supply in the cultivation system, and the highest ESC content (66.5%) and ESC productivity per mass of nitrogen (3.28gg(-1) (N) day(-1)) at N2, were all obtained under a high ICD of 8.0×10(6)cellsmL(-1). Therefore I. zhangjiangensis qualifies for ESC-enriched biomass production with economized nitrogen utilization. Copyright © 2015 Elsevier Ltd. All rights reserved.

Using nitrogen concentration and isotopic composition in lichens to spatially assess the relative contribution of atmospheric nitrogen sources in complex landscapes

International Nuclear Information System (INIS)

Pinho, P.; Barros, C.; Augusto, S.; Pereira, M.J.

2017-01-01

Reactive nitrogen (Nr) is an important driver of global change, causing alterations in ecosystem biodiversity and functionality. Environmental assessments require monitoring the emission and deposition of both the amount and types of Nr. This is especially important in heterogeneous landscapes, as different land-cover types emit particular forms of Nr to the atmosphere, which can impact ecosystems distinctively. Such assessments require high spatial resolution maps that also integrate temporal variations, and can only be feasibly achieved by using ecological indicators. Our aim was to rank land-cover types according to the amount and form of emitted atmospheric Nr in a complex landscape with multiple sources of N. To do so, we measured and mapped nitrogen concentration and isotopic composition in lichen thalli, which we then related to land-cover data. Results suggested that, at the landscape scale, intensive agriculture and urban areas were the most important sources of Nr to the atmosphere. Additionally, the ocean greatly influences Nr in land, by providing air with low Nr concentration and a unique isotopic composition. These results have important consequences for managing air pollution at the regional level, as they provide critical information for modeling Nr emission and deposition across regional as well as continental scales. - Highlights: • Which land-cover types are reactive nitrogen sources or sinks at a landscape level? • Nitrogen concentration and isotopic composition were analyzed in lichens. • This allowed determination of the main nitrogen sources: agricultural and urban areas. • Marine sources provided persistent low concentrations of reactive nitrogen. • The typical signature of each source was also determined. - Reactive-nitrogen concentration and isotopic composition in lichens were used to rank Nr sources at a landscape level.