Nitrogen Trace Research Articles

Nitrogen isotope and trace element composition characteristics of the Lower Cambrian Niutitang Formation shale in the upper -middle Yangtze region, South China

The Early Cambrian is a key interval in the global development of biological evolution, in which occurred many important environmental events and organic-rich sedimentary layers were deposited, which formed important hydrocarbon source rocks. The Lower Cambrian Niutitang Formation is one of the most important marine sedimentary layers in the Yangtze region, South China, and it records abundant important geological information that can be used for the reconstruction of the Lower Cambrian paleo-climates and paleo-environments.Nitrogen isotope compositions record and reflect variations in the original sedimentary environment and the redox conditions of marine ecosystems. Trace elements are also reliable indicators of sedimentary environments. In this study, we collected samples from the Lower Cambrian Niutitang Formation shale in the upper-middle Yangtze region of South China and measured the nitrogen isotope values of bulk sediments (δ15Nbulk), as well as their organic carbon isotope values (δ13Corg), total organic carbon (TOC) contents, total nitrogen (TN) contents and trace element concentrations. The δ15Nbulk values of the Niutitang shale range from 0.6‰ to 2.8‰, they show a certain positive excursion from bottom to top in the longitudinal direction, and they exhibit a significant correlation with the longitudinal variations in trace elements. These trace element characteristics suggest that the lower section of the Niutitang Formation existed in a strongly reduced sedimentary environment and was located in a hydrothermally active layer. During the deposition of the lower section of black shale, the nitrogen cycle was dominated by anaerobic nitrogen fixation; thus, its nitrogen isotope values are relatively lighter. In contrast, during the deposition of the upper section of the Niutitang Formation, the redox conditions of water column were unstable, the oxygen contents increased, and oxygenated reactions were intermittent or localized; thus producing relatively strong isotopic fractionation and causing the δ15Nbulk values in the upper section of black shale to exhibit a positive excursion. We conclude that the sedimentary environment is the key factor affecting nitrogen isotopes and that the redox conditions of the water column exhibit a significant correlation with the nitrogen isotope values.

Natural Gas Pipelines Leakage, Toxicity and its Safety Measures

A fugitive emission of natural gas during the extraction of oil and gas and its transportation through the pipeline has potential threat to the environment. Natural gas (NG) is the mixture of hydrocarbon gases consisting primarily of methane and other varying hydrocarbons, a small fraction of carbon dioxide, hydrogen, nitrogen, hydrogen sulphide and rare trace gases like helium, neon, xenon etc. The colorless and odorless NG has a wide range of applications as a cleaner fuel. The rapid urbanization, industrialization and economic growth all over the world demand the increasing transportation capacity of NG. Though the transportation pipeline are laid with well-equipped sophisticated technology and leak detection sensors, however still there are risk factor associated for leakage of the gases and explosion. The impacts of man-made disaster are in terms of deaths, injury, losses in economics, property and also having the adverse effect on ecology. The integrity of the NG pipeline system can be achieved by adopting continuous sophisticated up gradation technology. It also requires operation and maintenance of the pipeline at regular interval.

Effects of trace of nitrogen on the helium atmospheric pressure plasma jet interacting with a dielectric substrate

Experimental observations and simulation results regarding a pure He atmospheric pressure plasma jet (APPJ) and He + N2 APPJs interacting with a downstream dielectric substrate are presented in this paper. Experiments utilizing spatial-temporal imaging show that, in the case of the pure He APPJ, an annular plasma-substrate interaction pattern is formed. With the introduction of N2, the plasma is more uniformly distributed on the substrate surface, appearing a solid interaction pattern. The experimental measurements indicate 0.5% N2 mixture is the optimal condition to achieve the most intense discharge, while the plasma-substrate contact area is slightly reduced by 6.1% in comparison to that of the pure He APPJ. A 2D self-consistent fluid model is constructed to provide insights into the role of the addition of trace of N2 on the discharge dynamics. The discharge morphologies predicated by the model is in principle consistent with the experimental observations. The simulation reveals that the conversion from the annular plasma-substrate interaction pattern to the solid one is attributed to the synthetic effect of the addition of N2 and the presentence of the substrate acting as the cathode to enhance the local electric field. In the solid interaction pattern, the Penning ionization makes a significant contribution to the surface discharge, especially in the afterglow region. The dominant positive ions ( and ) and the reactive oxygen and nitrogen species including O and N gain remarkable increment in the flux intensity to the central surface, which merits great application potential.

Partitioning of Ag and CeO2 nanoparticles versus Ag and Ce ions in soil suspensions and effect of natural organic matter on CeO2 nanoparticles stability

This study examined the solid-liquid distribution of 14.8-nm Ag and 6.2-nm CeO2 nanoparticles in soil suspensions and compared it to that of Ag+ and Ce3+ ions, to better understand their environmental behaviour and fate. After 24 h incubation, more than 51% or 29% of the spiked amounts of Ag or CeO2 nanoparticles, respectively, can be retrieved in the liquid phase of (re)suspended soils. The Ag or Ce concentration remaining in solution depends on the incubation time and was influenced by soil properties. Significant correlations are obtained between, on the one hand, the relative amounts of Ag or CeO2 nanoparticles in suspension and the soil-pH, CEC, texture, suspended matter, nitrogen, phosphorus, TOC and main and trace elements content on the other hand. The presence of dissolved natural organic matter stabilizes CeO2 nanoparticles in the aqueous phase. In soil suspensions, Ag+ and Ce3+ ions seemingly interact more strongly with soil constituents compared to their nanoparticle counterparts, rendering the Ag and CeO2 nanoparticles to be more stable and potentially bioavailable.

Beyond the mean: A comparison of trace- and macroelement correlation profiles of two lacustrine populations of the crayfish Procambarus clarkii

In invertebrate biomonitors of chemical pollution, emphasis has been generally given to mean accumulation patterns and how they reflect varying environmental levels of contamination. Intra-population variability, and how it relates with individual phenotypic traits, has received less attention. Here, a set of analytes including trace elements (B, Ba, Cd, Cr, Cu, Fe, Li, Mn, Ni, Pb, Sr, V, and Zn), macroelements (C, Ca, K, Mg, N, Na), and carbon and nitrogen stable isotopes (δ13C and δ15N) was measured in two populations of the crayfish Procambarus clarkii from Lake Trasimeno and Lake Bolsena (Central Italy). The influence of location, sex, body size, and condition factor was assessed; in addition, the analyte correlation profiles of the two populations were compared to verify their congruence. In general, significant inter-lake differences were observed in the concentration of both trace- and macroelements in crayfish tissues, generally mirroring the local chemistry of water and of benthic non-living matrices (sediment and plant detritus). Crayfish CN isotopic signatures excluded the occurrence of inter-lake variations in their omnivorous trophic habits. Correlation profiles varied considerably between the two populations in the nature and strength of bivariate relationships. However, Mantel tests and procrustean analyses indicated a general, significant congruence; C, N, and, to a lesser extent K, Li, Ni, Pb, and δ13C showed the highest procrustean residuals, suggesting that their associations with other analytes may be partially influenced by inter-population differences in growing phases. Our study indicates that the local geochemistry of the lacustrine environment influences the elemental fingerprint of Procambarus clarkii; the considerable inter-individual variability in the concentration of analytes, however, does not significantly reflect on their association, thus corroborating its effectiveness as an indicator species.

IMPROVEMENT OF BIOGAS UPGRADING PROCESS USING CHEMICAL ABSORPTION AT AMBIENT CONDITIONS

Biogas major components are methane, carbon dioxide and traces of hydrogen sulfide, ammonia and nitrogen. Biogas upgrading process is the process by which carbon dioxide (composing 40 % of the biogas) is removed. In this study chemical absorption process using three different solvents (10 – 30 % monoethanolamine, 4 – 12 % sodium hydroxide and 5 – 15 % aqueous ammonia) was performed to produce methane-enriched biogas. A laboratory-scale packed-column apparatus containing efficient and cheap packing material (plastic bioball) was used to perform the experimental work in this study. Initial absorption runs were performed to select the best solvent type and concentration. Monoethanolamine (MEA) was proven to have the highest ability in producing upgraded biogas using a single absorption column apparatus at ambient conditions. The liquid to gas flow ratio was investigated using 30 % MEA solution. Optimum liquid to gas flow ratio for biogas upgrading process was determined to be about 18 (on mass basis). Biogas with methane content up to 96.1 v/v% was produced with CO2 loading capacity up to 0.24 mole-CO2 per mole-MEA.

Measurement of trace impurities in ultra pure hydrogen and deuterium at the parts-per-billion level using gas chromatography

A series of muon experiments at the Paul Scherrer Institute in Switzerland deploy ultra-pure hydrogen active targets. A new gas impurity analysis technique was developed, based on conventional gas chromatography, with the capability to measure part-per-billion (ppb) traces of nitrogen and oxygen in hydrogen and deuterium. Key ingredients are a cryogenic admixture accumulation, a directly connected sampling system and a dedicated calibration setup. The dependence of the measured concentration on the sample volume was investigated, confirming that all impurities from the sample gas are collected in the accumulation column and measured with the gas chromatograph. The system was calibrated utilizing dynamic dilution of admixtures into the gas flow down to sub-ppb level concentrations. The total amount of impurities accumulated in the purification system during a three month long experimental run was measured and agreed well with the calculated amount based on the measured concentrations in the flow.

Role of non-hydrocarbon constituents in crude oils correlation and heavy fractions processing studies

Eleven crude oils from the Gulf of Suez and Western Desert of Egypt have been used for the geochemical study. They have been analyzed for their metals, nitrogen and sulfur contents. Application of geochemical markers based upon these constituents has shown that crude oils could be correlated or differentiated according to their geologic age. The V/Ni, Ni/S, V/N, Ni/N, and S/N markers were almost uniform in Miocene oils, revealing the same origin, yet showing marked differences in Cretaceous crude oils reflecting varying degrees of their maturity, source materials, depositional environment and migrational history. The significance of analyzing the non-hydrocarbon constituents of the heavy petroleum fractions were extended to protecting the catalyst used in cracking processes. The results showed that trace metals and nitrogen contents are within the permissible limits in gas and diesel oils yet they are much beyond those limits in the heavier fractions.

Measurement of metabolic fluxes using stable isotope tracers in whole animals and human patients.

Metabolic flux analysis using stable isotope labeled substrates allows for the tracing of carbon, nitrogen, and hydrogen atoms through metabolic pathways and is an invaluable tool for investigating dynamic metabolic changes occurring in health and disease. Studies of flux analysis in vivo are more technically challenging than in vitro or ex vivo but provide a highly detailed view of organ and/or systemic metabolism. We review here recent efforts in studies of diet and nutrition, non-small cell lung cancer, ischemia/reperfusion injury, and hemorrhagic shock where in vivo flux analysis was utilized to analyze metabolic modulation. Recent technical strides in the field of metabolomics afford sensitive and quantitative in vivo measurements of metabolic fluxes. Stable isotope tracing with C-glucose, C, N-glutamine, C-propionate, and other substrates are used in combination or in parallel to investigate the interplays among central carbon metabolic pathways and many other areas of the metabolome. Stable isotope tracing in vivo provides opportunities to investigate physiological processes in the context of the whole animal. These approaches, often NMR spectroscopy or mass spectrometry (MS)-based, are growing in use and will likely find key applications in studying systemic disease, sports physiology, cancer metabolism, and personalized medicine.

Yield, resource use efficiency and trace metal uptake of weeping lovegrass grown on municipal sludge-amended soil.

There are concerns that fertilization using sludge in semi-arid areas, where water is limiting, will compound the effect of drought, resulting in the decline of yield from potential salt accumulation. This study investigated impacts of annual sludge application at 0, 4, 8 and 16 Mg ha-1 on weeping lovegrass hay yield, crude protein (CP) content, rainfall use efficiency (RUE), nitrogen use efficiency (NUE) and trace metal uptake over eight consecutive years. Both hay yield and RUE increased by 5-53% as the sludge rate increased. Hay yield was highest (13.3 Mg ha-1 ) during the wet season and RUE (27.1 kg mm-1 ) during the dry season. RUE was highest at sludge rates of 16 Mg ha-1 and NUE at 4 Mg ha-1 . Similarly, municipal sludge application increased CP content as well as crop Cr and Zn uptake from the 16 Mg ha-1 treatment. Results from this study indicated that eight consecutive years of treated municipal sludge application increased weeping lovegrass hay yield, CP content and RUE. Similarly, trace metal uptake by crop did not differ between the zero control and the 16 Mg ha-1 treatment, except for Zn and Cr, which showed a slight increment. Nonetheless, all trace metals remained well below the maximum tolerable dietary concentrations for domestic animals. © 2017 Society of Chemical Industry.

Effects of inhibitors and biochar on nitrous oxide emissions, nitrate leaching, and plant nitrogen uptake from urine patches of grazing animals on grasslands: a meta-analysis

ABSTRACTExcreta (urine and dung) patches on grazed grasslands are significant sources of nitrogen (N) trace gas emissions and leaching. Nitrification inhibitors (NIs), urease inhibitors (UIs) and biochar have been tested to reduce N losses and increase N utilization in various agro-ecosystems. Although the effectiveness of NIs, UIs or biochar on N losses or N utilization for chemical N fertilizers and manures have been evaluated in previous studies, there has been no comprehensive assessment on their effectiveness for excreta patches of grazing animals on grassland. This study thus aims to better understand the effects of inhibitors and biochar on the major N dynamics in excreta patches. Thus, we analyzed the results of 44 studies (156, 65, 67, and 97 comparisons of N2O emissions, NO3− leaching, plant N uptake, and plant yields, respectively) to evaluate the effects of additives on N losses and uptake from excreta patches. Our results showed that compared with urine patches without additives, pyrazole derivatives (a NI), N-(n-butyl) thiophosphoric triamide (NBPT, a UI), and biochar did not affect N2O emissions, whereas dicyandiamide (DCD, a NI) and a combination of NBPT and DCD (NBPT + DCD) significantly reduced emissions by 51% and 48%, respectively. DCD and NBPT + DCD also significantly reduced NO3− leaching (46% and 42%, respectively), and increased plant N uptake (14% and 15%, respectively) and plant yields (7% and 12%, respectively). Our findings suggest that the application of DCD was effective in decreasing N losses and increasing N utilization from urine patches, but NBPT + DCD would be a better option, in order to avoid the potential increases in ammonia emissions following DCD application. However, the potential adverse impacts and economic viability of using the inhibitors should be evaluated fully before their large-scale application.

Effect of nutritional bio-stimulants (NBS) on the biological treatment of the wastewater from traditional Chinese medicine production

Nutritional bio-stimulant (NBS) technology is an attractive method to improve the efficiency of biological treatment of wastewater by stimulating the microbial growth and increasing species diversity. In this study, a commercial NBS, which consisted of organic acids, absorbable nitrogen and phosphorus and trace elements, was applied as a nutrient supplement to replace conventional chemical fertilizer (CCF) in aerobic biological treatment of a traditional Chinese medicine (TCM) wastewater. A mill trials was carried out in a commercial scale TCM wastewater treatment system for 41 days. The process performance and active sludge characteristics were continuously monitored when the CCF was replaced with NBS gradually in the system. It was found that the chemical oxygen demand (COD) of the effluent decreased from 118 to 89 mg·L^-1, well below the 100 mg·L^-1 wastewater discharge limit, when the CCF was replaced with NBS completely. More importantly, the ammonia concentration of the effluent stayed constantly low in the NBS stage of the trial, indicating that the added NBS was completely utilized by the microorganisms. In contrast, the effluent ammonia concentration was gradually increasing and exceeded the limit in the CCF stage of the trial, indicating that the CCF was not fully utilized by the microbes. The improved perfromance of the aerobic wastewater treatment system was attributed to the fact that the NBS nutrients were more bio-available than the CCF to the microorganisms.

Trace elements in surface sediments from Kongsfjorden, Svalbard: occurrence, sources and bioavailability

ABSTRACTConcentration levels, potential sources and bioavailability of trace elements in marine sediments from Kongsfjorden (Svalbard Islands, Norwegian Arctic) were assessed and discussed. Surface sediments were collected by a Ponar grab and characterised in terms of mineralogical composition, grain-size distribution, total organic carbon and nitrogen percentage contents, and major and trace elements concentrations. Anthropogenic and natural sources of trace elements were inferred from lead isotope ratios, while the potential metal bioavailability was evaluated by size-fractionation and solid-phase speciation studies and by the analysis of acid-volatile sulphides (AVS) and simultaneously extracted metals (SEM). Concentrations of metals, their enrichment factors and solid speciation patterns collectively indicated that the anthropogenic impact of trace elements in the fjord is generally low, with a minor enrichment with respect to crustal values (by a factor of 2–11) for As, Cr, Ni and V. The lead isotope ratios (208Pb/207Pb: 2.474–2.498 and 206Pb/207Pb: 1.206–1.212) were close to the natural signature except in the outer fjord, due to the influence of the Atlantic marine circulation. Many elements of toxicological concern (e.g. Pb, V, Zn) were enriched in the finest sediment fraction, which was by far the preponderant one, especially in the inner fjord. However, less than 15% of most trace elements (exceptions Cd and Mn) in the finest fraction was actually associated with easily leachable sediment phases. Finally, the high SEM/AVS ratios determined on samples from sites close to the glacier fronts (11–15), due to low AVS content, highlighted that the sediment in that zone cannot remove additional inputs of heavy metals by sulphide precipitation.

Marine redox evolution in the early Cambrian Yangtze shelf margin area: evidence from trace elements, nitrogen and sulphur isotopes

AbstractNitrogen is an essential element for biological activity, and nitrogen isotopic compositions of geological samples record information about both marine biological processes and environmental evolution. However, only a few studies of N isotopes in the early Cambrian have been published. In this study, we analysed nitrogen isotopic compositions, as well as trace elements and sulphur isotopic compositions of cherts, black shales, carbonaceous shales and argillaceous carbonates from the Daotuo drill core in Songtao County, NE Guizhou Province, China, to reconstruct the marine redox environment of both deep and surface seawater in the study area of the Yangtze shelf margin in the early Cambrian. The Mo–U covariation pattern of the studied samples indicates that the Yangtze shelf margin area was weakly restricted and connected to the open ocean through shallow water flows. Mo and U concentrations, δ15Nbulk and δ34Spy values of the studied samples from the Yangtze shelf margin area suggest ferruginous but not sulphidic seawater and low marine sulphate concentration (relatively deep chemocline) in the Cambrian Fortunian and early Stage 2; sulphidic conditions (shallow chemocline and anoxic photic zone) in the upper Cambrian Stage 2 and lower Stage 3; and the depression of sulphidic seawater in the middle and upper Cambrian Stage 3. Furthermore, the decreasing δ15N values indicate shrinking of the marine nitrate reservoir during the middle and upper Stage 3, which reflects a falling oxygenation level in this period. The environmental evolution was probably controlled by the changing biological activity through its feedback on the local marine environment.

Uranium aerosols at a nuclear fuel fabrication plant: Characterization using scanning electron microscopy and energy dispersive X-ray spectroscopy

Detailed aerosol knowledge is essential in numerous applications, including risk assessment in nuclear industry. Cascade impactor sampling of uranium aerosols in the breathing zone of nuclear operators was carried out at a nuclear fuel fabrication plant. Collected aerosols were evaluated using scanning electron microscopy and energy dispersive X-ray spectroscopy. Imaging revealed remarkable variations in aerosol morphology at the different workshops, and a presence of very large particles (up to≅100×50μm2) in the operator breathing zone. Characteristic X-ray analysis showed varying uranium weight percentages of aerosols and, frequently, traces of nitrogen, fluorine and iron. The analysis method, in combination with cascade impactor sampling, can be a powerful tool for characterization of aerosols. The uranium aerosol source term for risk assessment in nuclear fuel fabrication appears to be highly complex.

Gas purge microsyringe extraction coupled to comprehensive two-dimensional gas chromatography for the characterization of petroleum migration

Several nitrogen-containing compounds play important roles as molecular indicators in petroleum migration but are usually absent or present at very low concentrations, especially when oils have been subjected to severe biodegradation or water washing. In this study, we use thiophenic compounds (such as dibenzothiophene and its alkylated homologs) as alternative oil migration indicators because they appear to exhibit strong absorption/adsorption interactions with solid organic/mineral phases due to their molecular structure, similar to organic nitrogen compounds. To improve the detection sensitivity of trace analytes, a gas purge microsyringe extraction (GP-MSE) device was developed and coupled to comprehensive two-dimensional gas chromatography/time-of-flight mass spectrometry (GC×GC-TOFMS) for the simultaneous analysis of biomarkers and trace nitrogen- and sulfur-containing compounds in crude oils. Twenty oil samples collected from the Hashan region of the Junggar Basin in China were classified as having different biodegradation levels and confirmed to be primarily sourced from the Fengcheng Formation with similar maturities and depositional environments. In addition to the commonly used oil migration parameters derived from the distribution of organic nitrogen compounds, several geochemical parameters based on the ratios of 4,6-/1,4-, 4,6-/3,6- and 4,6-/2,7-dimethyldibenzothiophenes (DMDBTs) were proposed to indicate the oil migration direction. The conclusions on oil migration obtained from organic nitrogen compounds and DMDBTs were in good agreement and further supported by other geological evidence. An oil migration model for the region was developed by combining the geochemical data with the geological information.

Influence of Trace Nitrogen Oxides on Natural Gas Oxidation: Flow Reactor Measurements and Kinetic Modeling

The reactivity-promoting effect of trace nitrogen oxides (NOx) on post-induction oxidation of a synthetic natural gas (2% ethane in methane) has been experimentally studied in a high-pressure laminar flow reactor (HPLFR) at 10 ± 0.1 atm, nominal reaction temperature of 818 ± 5 K, and several equivalence ratios (φ ∼ 0.5, 1.0, and 2.0). Each set of experimental measurements was simulated using several literature C0–C2 + NOx kinetic models, both recent and legacy, using approaches shown to lead to robust interpretation of present experimental conditions. Coupling between the NOx and C0–C2 submodel components of these models varies significantly in both qualitative (mechanistic) and quantitative character. A comparison among the experimental measurements and modeling results serves to highlight important kinetic features particular to application-relevant natural gas oxidation in presence of trace (∼25 ppm) NOx. Additional insight is offered by a baseline experiment with no NOx perturbation, which shows that ...

Trace elements and nitrogen content in naturally growing moss Hypnum cupressiforme in urban and peri-urban forests of the Municipality of Ljubljana (Slovenia).

We monitored trace metals and nitrogen using naturally growing moss Hypnum cupressiforme Hedw. in urban and peri-urban forests of the City Municipality of Ljubljana. The aim of this study was to explore the differences in atmospheric deposition of trace metals and nitrogen between urban and peri-urban forests. Samples were collected at a total of 44 sites in urban forests (forests within the motorway ring road) and peri-urban forests (forests outside the motorway ring road). Mosses collected in urban forests showed increased trace metal concentrations compared to samples collected from peri-urban forests. Higher values were significant for As, Cr, Cu, Hg, Mo, Ni, Pb, Sb, Tl and V. Within the motorway ring road, the notable differences in element concentrations between the two urban forests were significant for Cr, Ni and Mo. Factor analysis showed three groups of elements, highlighting the contribution of traffic emissions, individual heating appliances and the resuspension of contaminated soils and dust as the main sources of trace elements in urban forests.

Progress in reducing ICRF-specific impurity release in ASDEX upgrade and JET

Use of new 3-strap ICRF antennas with all-tungsten (W) limiters in ASDEX Upgrade results in a reduction of the W sources at the antenna limiters and of the W content in the confined plasma by at least a factor of 2 compared to the W-limiter 2-strap antennas used in the past. The reduction is observed with a broad range of plasma shapes. In multiple locations of antenna frame, the limiter W source has a minimum when RF image currents are decreased by cancellation of the RF current contributions of the central and the outer straps. In JET with ITER-like wall, ITER-like antenna produces about 20% less of main chamber radiation and of W content compared to the old A2 antennas. However the effect of the A2 antennas on W content is scattered depending on which antennas are powered. Experiments in JET with trace nitrogen (N2) injection show that a presence of active ICRF antenna close to the midplane injection valve has little effect on the core N content, both in dipole and in -90° phasing. This indicates that the effect of ICRF on impurity transport across the scape-off-layer is small in JET compared to the dominant effect on impurity sources leading to increased impurity levels during ICRF operation.

Land’s complex role in climate change

To mitigate climate change at local, regional, and global scales, we must begin to think beyond greenhouse gases.