Enhanced nitrogen selectivity for nitrate reduction on Cu-nZVI by TiO2 photocatalysts under UV irradiation

NASA Astrophysics Data System (ADS)

Krasae, Nalinee; Wantala, Kitirote

2016-09-01

The aims of this work were to study the effect of Cu-nZVI with and without TiO2 on nitrate reduction and to study the pathway of nitrate reduction utilizing to nitrogen gas. The chemical and physical properties of Cu-nZVI and Cu-nZVI/TiO2 such as specific surface area, crystalline phase, oxidation state of Cu and Fe and morphology were determined by N2 adsorption-desorption Brunauer-Emmett-Teller (BET) analytical technique, X-ray diffraction (XRD), X-ray Absorption Near Edge Structure (XANES) technique and Transmittance Electron Microscopy (TEM). The full factorial design (FFD) was used in this experiment for the effect of Cu-nZVI with and without TiO2, where the initial solution pH was varied at 4, 5.5, and 7 and initial nitrate concentration was varied at 50, 75, and 100 ppm. Finally, the pathway of nitrate reduction was examined to calculate the nitrogen gas selectivity. The specific area of Cu-nZVI and Cu-nZVI/TiO2 was found to be about 4 and 36 m2/g, respectively. The XRD pattern of Fe0 in Cu-nZVI was found at 45° (2θ), whereas Cu-nZVI/TiO2 cannot be observed. TEM images can confirm the position of the core and the shell of nZVI for Fe0 and ferric oxide. Cu-nZVI/TiO2 proved to have higher activity in nitrogen reduction performance than that without TiO2 and nitrate can be completely degraded in both of solution pH of 4 and 7 in 75 ppm of initial nitrate concentration. It can be highlighted that the nitrogen gas selectivity of Cu-nZVI/TiO2 greater than 82% was found at an initial solution pH of 4 and 7. The main effects of Cu-nZVI with and without TiO2 and the initial nitrate concentration on nitrate reduction were significant. The interaction between solution pH and initial nitrate concentration and the interaction of all effects at a reaction time of 15 min on nitrate reduction were also significant.

[Effect of carbon substrate concentration on N2, N2O, NO, CO2, and CH4 emissions from a paddy soil in anaerobic condition].

PubMed

Chen, Nuo; Liao, Ting-ting; Wang, Rui; Zheng, Xun-hua; Hu, Rong-gui; Butterbach-Bahl, Klaus

2014-09-01

Understanding the effects of carbon and nitrogen substrates concentrations on the emissions of denitrification gases including nitrogen (N2) , nitrous oxide (N2O) and nitric oxide (NO), carbon dioxide (CO2) and methane (CH4) from anaerobic paddy soils is believed to be helpful for development of greenhouse gas mitigation strategies. Moreover, understanding the quantitative dependence of denitrification products compositions on carbon substrate concentration could provide some key parameters or parameterization scheme for developing process-oriented model(s) of nitrogen transformation. Using a silt loam soil collected from a paddy field, we investigated the influence of carbon substrate concentration on the emissions of the denitrification gases, CO2 and CH4 from anaerobically incubated soils by setting two treatments: control (CK) with initial soil nitrate and dissolved organic carbon (DOC) concentrations of ~ 50 mg.kg-1 and -28 mg kg-1 , respectively; and DOC added (C + ) with initial soil nitrate and DOC concentrations of ~50 mg.kg-1 and ~300 mg.kg-1 , respectively. The emissions of denitrification gases, CO2 and CH4, as well as concentrations of carbon and nitrogen substrates for each treatment were dynamically measured, using the gas-flow-soil-core technique and a paralleling substrate monitoring system. The results showed that CH4 emission was not observed in CK treatment while observed in C treatment. Aggregate emission of greenhouse gases for C + treatment was significantly higher comparing with the CK treatment (P <0. 01). The mass fractions of NO, N20 and N2 emissions in total nitrogen gases emissions were approximately 9% , 35% and 56% for CK treatment, respectively; and approximately 31% , 50% and 19% for C+ treatment, respectively, with significant differences between these two treatments (P < 0.01). The results indicated that carbon substrate concentrations can significantly change the composition of nitrogen gas emissions. The results also implicated that organic fertilizer should not be applied to nitrate-rich paddy soils prior to or during flooding so as to mitigate greenhouse gases emissions.

Treatment of Ammonia Nitrogen Wastewater in Low Concentration by Two-Stage Ozonization.

PubMed

Luo, Xianping; Yan, Qun; Wang, Chunying; Luo, Caigui; Zhou, Nana; Jian, Chensheng

2015-09-23

Ammonia nitrogen wastewater (about 100 mg/L) was treated by two-stage ozone oxidation method. The effects of ozone flow rate and initial pH on ammonia removal were studied, and the mechanism of ammonia nitrogen removal by ozone oxidation was discussed. After the primary stage of ozone oxidation, the ammonia removal efficiency reached 59.32% and pH decreased to 6.63 under conditions of 1 L/min ozone flow rate and initial pH 11. Then, the removal efficiency could be over 85% (the left ammonia concentration was lower than 15 mg/L) after the second stage, which means the wastewater could have met the national discharge standards of China. Besides, the mechanism of ammonia removal by ozone oxidation was proposed by detecting the products of the oxidation: ozone oxidation directly and ·OH oxidation; ammonia was mainly transformed into NO₃(-)-N, less into NO₂(-)-N, not into N₂.

Agronomic and environmental consequences of using liquid mineral concentrates on arable farms.

PubMed

Schils, René L M; Postma, Romke; van Rotterdam, Debby; Zwart, Kor B

2015-12-01

In regions with intensive livestock systems, the processing of manure into liquid mineral concentrates is seen as an option to increase the nutrient use efficiency of manures. The agricultural sector anticipates that these products may in future be regarded as regular mineral fertilisers. We assessed the agronomic suitability and impact on greenhouse gas (GHG) and ammonia emissions of using liquid mineral concentrates on arable farms. The phosphate requirements on arable farms were largely met by raw pig slurry, given its large regional availability. After the initial nutrient input by means of pig slurry, the nitrogen/phosphate ratio of the remaining nutrient crop requirements determined the additional amount of liquid mineral concentrates that can be used. For sandy soils, liquid mineral concentrates could supply 50% of the nitrogen requirement, whereas for clay soils the concentrates did not meet the required nitrogen/phosphate ratio. The total GHG emissions per kg of plant available nitrogen ranged from -65 to 33 kg CO2 -equivalents. It increased in the order digestates < mineral fertiliser < raw slurries. Liquid mineral concentrates had limited added value for arable farms. For an increased suitability it is necessary that liquid mineral concentrates do not contain phosphate and that the nitrogen availability is increased. In the manure-processing chain, anaerobic digestion had a dominant and beneficial effect on GHG emissions. © 2015 Society of Chemical Industry.

Electrochemical treatment of concentrate from reverse osmosis of sanitary landfill leachate.

PubMed

Labiadh, Lazhar; Fernandes, Annabel; Ciríaco, Lurdes; Pacheco, Maria José; Gadri, Abdellatif; Ammar, Salah; Lopes, Ana

2016-10-01

Conventional sanitary landfill leachate treatment has recently been complemented and, in some cases, completely replaced by reverse osmosis technology. Despite the good quality of treated water, the efficiency of the process is low and a large volume of reverse osmosis concentrate has to be either discharged or further treated. In this study, the use of anodic oxidation combined with electro-Fenton processes to treat the concentrate obtained in the reverse osmosis of sanitary landfill leachate was evaluated. The anodic oxidation pretreatment was performed in a pilot plant using an electrochemical cell with boron-doped diamond electrodes. In the electro-Fenton experiments, a boron-doped diamond anode and carbon-felt cathode were used, and the influence of the initial pH and iron concentration were studied. For the experimental conditions, the electro-Fenton assays performed at an initial pH of 3 had higher organic load removal levels, whereas the best nitrogen removal was attained when the electrochemical process was performed at the natural pH of 8.8. The increase in the iron concentration had an adverse impact on treatment under natural pH conditions, but it enhanced the nitrogen removal in the electro-Fenton assays performed at an initial pH of 3. The combined anodic oxidation and electro-Fenton process is useful for treating the reverse osmosis concentrate because it is effective at removing the organic load and nitrogen-containing species. Additionally, this process potentiates the increase in the biodegradability index of the treated effluent. Copyright © 2016 Elsevier Ltd. All rights reserved.

40 CFR 91.318 - Oxides of nitrogen analyzer calibration.

Code of Federal Regulations, 2012 CFR

2012-07-01

... nitrogen analyzer as described in this section. (b) Initial and periodic interference. Prior to its...-squares best-fit straight line is two percent or less of the value at each data point, concentration... two percent at any point, use the best-fit non-linear equation which represents the data to within two...

40 CFR 91.318 - Oxides of nitrogen analyzer calibration.

Code of Federal Regulations, 2014 CFR

2014-07-01

... nitrogen analyzer as described in this section. (b) Initial and periodic interference. Prior to its...-squares best-fit straight line is two percent or less of the value at each data point, concentration... two percent at any point, use the best-fit non-linear equation which represents the data to within two...

Modeling of nitrogen transformation in an integrated multi-trophic aquaculture (IMTA)

NASA Astrophysics Data System (ADS)

Silfiana; Widowati; Putro, S. P.; Udjiani, T.

2018-03-01

The dynamic model of nitrogen transformation in IMTA (Integrated Multi-Trophic Aquaculture) is purposed. IMTA is a polyculture with several biotas maintained in it to optimize waste recycling as a food source. The purpose of this paper is to predict nitrogen decrease and nitrogen transformation in IMTA consisting of ammonia (NH3), Nitrite (NO2) and Nitrate (NO3). Nitrogen transformation of several processes, nitrification, assimilation, and volatilization. Numerical simulations are performed by providing initial parameters and values based on a review of previous research. The numerical results show that the rate of change in nitrogen concentration in IMTA decrease and reaches stable at different times.

Respiration rate in maize roots is related to concentration of reduced nitrogen and proliferation of lateral roots

NASA Technical Reports Server (NTRS)

Granato, T. C.; Raper, C. D. Jr; Wilkerson, G. G.; Raper CD, J. r. (Principal Investigator)

1989-01-01

The relationship between specific rate of respiration (respiration rate per unit root dry weight) and concentration of reduced nitrogen was examined for maize (Zea mays L.) roots. Plants with 2 primary nodal root axes were grown for 8 days in a split-root hydroponic system in which NO3- was supplied to both axes at 1.0 mol m-3, to one axis at 1.0 mol m-3 and the other axis at 0.0 mol m-3, or to both axes at 0.0 mol m-3. Respiration rates and root characteristics were measured at 2-day intervals. Specific rate of respiration was positively correlated in a nonlinear relationship with concentration of reduced nitrogen. The lowest specific rates of respiration occurred when neither axis received exogenous NO3- and the concentration of reduced nitrogen in the axes was less than 9 mg g-1. The greatest rates occurred in axes that were actively absorbing NO3- and contained more than 35 mg g-1 of reduced nitrogen. At 23 mg g-1 of reduced nitrogen, below which initiation of lateral branches was decreased by 30-50%, specific rate of respiration was 17% greater for roots actively absorbing NO3- than for roots not absorbing NO3-. Increases in specific rate of respiration associated with concentrations of reduced nitrogen greater than 23 mg g-1 were concluded to be attributable primarily to proliferation of lateral branches.

Growth and fermentation patterns of Saccharomyces cerevisiae under different ammonium concentrations and its implications in winemaking industry.

PubMed

Mendes-Ferreira, A; Mendes-Faia, A; Leão, C

2004-01-01

To study the effects of assimilable nitrogen concentration on growth profile and on fermentation kinetics of Saccharomyces cerevisiae. Saccharomyces cerevisiae was grown in batch in a defined medium with glucose (200 g l(-1)) as the only carbon and energy source, and nitrogen supplied as ammonium sulphate or phosphate forms under different concentrations. The initial nitrogen concentration in the media had no effect on specific growth rates of the yeast strain PYCC 4072. However, fermentation rate and the time required for completion of the alcoholic fermentation were strongly dependent on nitrogen availability. At the stationary phase, the addition of ammonium was effective in increasing cell population, fermentation rate and ethanol. The yeast strain required a minimum of 267 mg N l(-1) to attain complete dryness of media, within the time considered for the experiments. Lower levels were enough to support growth, although leading to sluggish or stuck fermentation. The findings reported here contribute to elucidate the role of nitrogen on growth and fermentation performance of wine yeast. This information might be useful to the wine industry where excessive addition of nitrogen to prevent sluggish or stuck fermentation might have a negative impact on wine stability and quality. Copyright 2004 The Society for Applied Microbiology

Use of Plackett-Burman design for rapid screening of nitrogen and carbon sources for the production of lipase in solid state fermentation by Yarrowia lipolytica from mustard oil cake (Brassica napus).

PubMed

Imandi, Sarat Babu; Karanam, Sita Kumari; Garapati, Hanumantha Rao

2013-01-01

Mustard oil cake (Brassica napus), the residue obtained after extraction of mustard oil from mustard oil seeds, was investigated for the production of lipase under solid state fermentation (SSF) using the marine yeast Yarrowia lipolytica NCIM 3589. Process parameters such as incubation time, biomass concentration, initial moisture content, carbon source concentration and nitrogen source concentration of the medium were optimized. Screening of ten nitrogen and five carbon sources has been accomplished with the help of Plackett-Burman design. The highest lipase activity of 57.89 units per gram of dry fermented substrate (U/gds) was observed with the substrate of mustard oil cake in four days of fermentation.

A kinetic model for the thermal nitridation of SiO2/Si

NASA Technical Reports Server (NTRS)

Vasquez, R. P.; Madhukar, A.

1986-01-01

To explain the observed nitrogen distributions in thermally nitridated SiO2 films, a kinetic model is proposed in which the nitridation process is simulated, using the first-order chemical kinetics and Arrhenius dependence of the diffusion and reaction rates on temperature. The calculations show that initially, as the substrate reacts with diffusing nitrogen, a nitrogen-rich oxynitride forms at the SiO2-Si interface, while at nitridation temperatures above 1000 C, an oxygen-rich oxynitride subsequently forms at the interface, due to reaction of the substrate with an increasingly concentrated oxygen displaced by the slower nitridation of the SiO2. This sequence of events results in a nitrogen distribution in which the peak of the interfacial nitrogen concentration occurs away from the interface. The results are compared with the observed nitrogen distribution. The calculated results have correctly predicted the positions of the interfacial nitrogen peaks at the temperatures of 800, 1000, and 1150 C. To account for the observed width of the interfacial nitrogen distribution, it was found necessary to include in the simulations the effect of interfacial strain.

[Screening and ammoxidation characteristics of an ammonium oxidizing bacteria group].

PubMed

Yang, Xiaolong; Liu, Lihua; Wu, Bingqi; Liu, Shujie; Chen, Fuming

2015-12-04

This study aimed to screen high-performance ammonia oxidizing bacteria ( AOB) resistant to a high concentration of ammonia-nitrogen and low C/N ratio, for the development of novel AOB agents. Multi-point sampling, compulsory domestication, gradient dilution of domestication liquid were conducted to screen AOB with efficient and stable ammonia-nitrogen removing ability, and effects of different factors on its ammoxidation ability including C/N ratio, shaking speed and ammonia-nitrogen concentration were studied. Dominant strains were screened and identified by morphological observation, physiological and biochemical properties test and 16S rRNA sequence analysis. Three efficient AOB were obtained, among them a micro-flora named JQ8 showed the highest activity. The ammonia-nitrogen removal rate reached 95. 07% in a simulated wastewater with 17. 86 mmol/L of initial ammonia-nitrogen at C/N 4 treated by JQ8 for 6 days. Moreover, its ammonia nitrogen removal rate kept above 95% and net nitrogen removing rate nearly 80% in the solution with a C/N ratio above 4 and an NH₄⁺-N concentration below 28.57 mmol/L. The circuit board industry wastewater was treated using the laboratory-simulated aerobic active sludge disposal system. The removal rate of NH₄⁺-N and total nitrogen reached 87.8% and 67.6% respectively after 7 days' treatment using JQ8. Defluvibacter sp., Paracoccus sp. and Aquamicrobium sp. were identified as the dominant strains after the composition analysis of JQ8. An ammonia oxidizing bacteria consortium JQ8 screened from the landfill leachate showed a strong ammonium-nitrogen removal and endurance ability under low C/N ratio and high ammonia-nitrogen concentration, thus is probably applicable to intensify the ammonia-nitrogen removal treatment of industrial wastewater with sewage disposal system.

Simultaneous removal of ammonia nitrogen and manganese from wastewater using nitrite by electrochemical method.

PubMed

Shu, Jiancheng; Liu, Renlong; Liu, Zuohua; Qiu, Jiang; Chen, Hongliang; Tao, Changyuan

2017-02-01

In this work, nitrite was developed to simultaneously remove manganese and ammonia nitrogen from wastewater by the electrochemical method. The characteristics of electrolytic reaction were observed via cyclic voltammograms. Moreover, the mole ratio of nitrite and ammonia nitrogen, voltage, and initial pH value, which affected the removal efficiency of ammonia nitrogen and manganese, were investigated. The results showed that the concentration of ammonia nitrogen in wastewater could be reduced from 120.2 to 6.0 mg L -1 , and manganese could be simultaneously removed from 302.4 to 1.5 mg L -1 at initial pH of 8.0, the mole ratios of nitrite and ammonia nitrogen of 1.5:1, and voltage of 20 V direct current electrolysis for 4.0 h. XRD analysis showed that manganese dioxide was deposited on the anode, and manganese was mainly removed in the form of manganese hydroxide precipitation in the cathode chamber.

Removal of organic matter and ammonia nitrogen from landfill leachate by ultrasound.

PubMed

Wang, Songlin; Wu, Xiaohui; Wang, Yansong; Li, Qifen; Tao, Meijun

2008-09-01

Experiments on the removal of organic matters and ammonia nitrogen from landfill leachate by ultrasound irradiation were carried out. The effects of COD reduction and ammonia removal of power input, initial concentration, initial pH and aeration were studied. It was found that the sonolysis of organic matters proceeds via reaction with ()OH radicals; a thermal reaction also occurs with a small contribution. The rise of COD at some intervals could be explained by the complexity of organic pollutant sonolysis in landfill leachate. Ultrasonic irradiation was shown to be an effective method for the removal of ammonia nitrogen from landfill leachate. After 180 min ultrasound irradiation, up to 96% ammonia nitrogen removal efficiency can be obtained. It was found that the mechanism of ammonia nitrogen removal by ultrasound irradiation is largely that the free ammonia molecules in leachate enter into the cavitation bubbles and transform into nitrogen molecules and hydrogen molecules via pyrolysis under instant high temperature and high pressure in the cavitation bubbles.

Evaluation of the increase in threading dislocation during the initial stage of physical vapor transport growth of 4H-SiC

NASA Astrophysics Data System (ADS)

Suo, Hiromasa; Tsukimoto, Susumu; Eto, Kazuma; Osawa, Hiroshi; Kato, Tomohisa; Okumura, Hajime

2018-06-01

The increase in threading dislocation during the initial stage of physical vapor transport growth of n-type 4H-SiC crystals was evaluated by cross-sectional X-ray topography. Crystals were grown under two different temperature conditions. A significant increase in threading dislocation was observed in crystals grown at a high, not low, temperature. The local strain distribution in the vicinity of the grown/seed crystal interface was evaluated using the electron backscatter diffraction technique. The local nitrogen concentration distribution was also evaluated by time-of-flight secondary ion mass spectrometry. We discuss the relationship between the increase in threading dislocation and the local strain due to thermal stress and nitrogen concentration.

Nitrogen and carbon source balance determines longevity, independently of fermentative or respiratory metabolism in the yeast Saccharomyces cerevisiae.

PubMed

Santos, Júlia; Leitão-Correia, Fernanda; Sousa, Maria João; Leão, Cecília

2016-04-26

Dietary regimens have proven to delay aging and age-associated diseases in several eukaryotic model organisms but the input of nutritional balance to longevity regulation is still poorly understood. Here, we present data on the role of single carbon and nitrogen sources and their interplay in yeast longevity. Data demonstrate that ammonium, a rich nitrogen source, decreases chronological life span (CLS) of the prototrophic Saccharomyces cerevisiae strain PYCC 4072 in a concentration-dependent manner and, accordingly, that CLS can be extended through ammonium restriction, even in conditions of initial glucose abundance. We further show that CLS extension depends on initial ammonium and glucose concentrations in the growth medium, as long as other nutrients are not limiting. Glutamine, another rich nitrogen source, induced CLS shortening similarly to ammonium, but this effect was not observed with the poor nitrogen source urea. Ammonium decreased yeast CLS independently of the metabolic process activated during aging, either respiration or fermentation, and induced replication stress inhibiting a proper cell cycle arrest in G0/G1 phase. The present results shade new light on the nutritional equilibrium as a key factor on cell longevity and may contribute for the definition of interventions to promote life span and healthy aging.

Nitrate Remediation of Soil and Groundwater Using Phytoremediation: Transfer of Nitrogen Containing Compounds from the Subsurface to Surface Vegetation

NASA Astrophysics Data System (ADS)

Nelson, Sheldon

2013-04-01

Nitrate Remediation of Soil and Groundwater Using Phytoremediation: Transfer of Nitrogen Containing Compounds from the Subsurface to Surface Vegetation Sheldon Nelson Chevron Energy Technology Company 6001 Bollinger Canyon Road San Ramon, California 94583 snne@chevron.com The basic concept of using a plant-based remedial approach (phytoremediation) for nitrogen containing compounds is the incorporation and transformation of the inorganic nitrogen from the soil and/or groundwater (nitrate, ammonium) into plant biomass, thereby removing the constituent from the subsurface. There is a general preference in many plants for the ammonium nitrogen form during the early growth stage, with the uptake and accumulation of nitrate often increasing as the plant matures. The synthesis process refers to the variety of biochemical mechanisms that use ammonium or nitrate compounds to primarily form plant proteins, and to a lesser extent other nitrogen containing organic compounds. The shallow soil at the former warehouse facility test site is impacted primarily by elevated concentrations of nitrate, with a minimal presence of ammonium. Dissolved nitrate (NO3-) is the primary dissolved nitrogen compound in on-site groundwater, historically reaching concentrations of 1000 mg/L. The initial phases of the project consisted of the installation of approximately 1750 trees, planted in 10-foot centers in the areas impacted by nitrate and ammonia in the shallow soil and groundwater. As of the most recent groundwater analytical data, dissolved nitrate reductions of 40% to 96% have been observed in monitor wells located both within, and immediately downgradient of the planted area. In summary, an evaluation of time series groundwater analytical data from the initial planted groves suggests that the trees are an effective means of transfering nitrogen compounds from the subsurface to overlying vegetation. The mechanism of concentration reduction may be the uptake of residual nitrate from the vadose zone, the direct uptake of dissolved constituent from the upper portion of the saturated zone/capillary fringe, or a combination of these two processes.

Treatment of Ammonia Nitrogen Wastewater in Low Concentration by Two-Stage Ozonization

PubMed Central

Luo, Xianping; Yan, Qun; Wang, Chunying; Luo, Caigui; Zhou, Nana; Jian, Chensheng

2015-01-01

Ammonia nitrogen wastewater (about 100 mg/L) was treated by two-stage ozone oxidation method. The effects of ozone flow rate and initial pH on ammonia removal were studied, and the mechanism of ammonia nitrogen removal by ozone oxidation was discussed. After the primary stage of ozone oxidation, the ammonia removal efficiency reached 59.32% and pH decreased to 6.63 under conditions of 1 L/min ozone flow rate and initial pH 11. Then, the removal efficiency could be over 85% (the left ammonia concentration was lower than 15 mg/L) after the second stage, which means the wastewater could have met the national discharge standards of China. Besides, the mechanism of ammonia removal by ozone oxidation was proposed by detecting the products of the oxidation: ozone oxidation directly and ·OH oxidation; ammonia was mainly transformed into NO3−-N, less into NO2−-N, not into N2. PMID:26404353

Biohydrogen production from lactose: influence of substrate and nitrogen concentration.

PubMed

Moreno, R; Fierro, J; Fernández, C; Cuetos, M J; Gómez, X

2015-01-01

Hydrogen produced from renewable sources may be considered the energy vector of the future. However, reducing process costs is imperative in order to achieve this goal. In the present research, the effect of nitrogen (N), initial pH and substrate content for starting up the dark fermentative process was studied using the response surface methodology. Anaerobic digested dried sludge (biosolid pellets) was used as the inoculum. Synthetic wastewater was used as the substrate in batch reactors. A decrease in H2 production was observed with the increase in N and lactose concentrations. This drop was considerably greater when the concentration of lactose was at its lower level. Although the increase in lactose concentration results in a lower H2 production, the effect of N on the response is attenuated at higher levels of lactose. On the other hand, the effect of initial pH on the fermentation system was not significant. The evaluation on the process under semi-continuous conditions was performed using anaerobic sequencing batch reactors (ASBRs). The process was evaluated at different C/N ratios using synthetic wastewater. Results showed higher hydrogen yields with the gradual decrease in nitrogen content. The addition of cheese whey to the ASBR resulted in a H2 production rate of 0.18 L H2 L(-1) d(-1).

Carbon Dioxide Enrichment: Data on the Response of Cotton to Varying CO2 Irrigation, and Nitrogen (NDP-037)

DOE Data Explorer

Kimball, B. A. [US Dept. of Agriculture (USDA)., Agricultural Research Service, Phoenix, AZ (United States); Mauney, J. R. [US Dept. of Agriculture (USDA)., Agricultural Research Service, Phoenix, AZ (United States); La Morte, R. L. [US Dept. of Agriculture (USDA)., Agricultural Research Service, Phoenix, AZ (United States); Guinn, G. [US Dept. of Agriculture (USDA)., Agricultural Research Service, Phoenix, AZ (United States); Nakayama, F. S. [US Dept. of Agriculture (USDA)., Agricultural Research Service, Phoenix, AZ (United States); Radin, J. W. [US Dept. of Agriculture (USDA)., Agricultural Research Service, Phoenix, AZ (United States); Lakatos, E. A. [University of Arizona, Tucson, AZ (United States); Mitchell, S. T. [US Dept. of Agriculture (USDA)., Agricultural Research Service, Phoenix, AZ (United States); Parker, L. L. [US Dept. of Agriculture (USDA)., Agricultural Research Service, Phoenix, AZ (United States); Peresta, G. J. [US Dept. of Agriculture (USDA)., Agricultural Research Service, Phoenix, AZ (United States); Nixon III, P. E. [US Dept. of Agriculture (USDA)., Agricultural Research Service, Phoenix, AZ (United States); Savoy, B. [US Dept. of Agriculture (USDA)., Agricultural Research Service, Phoenix, AZ (United States); Harris, S. M. [US Dept. of Agriculture (USDA)., Agricultural Research Service, Phoenix, AZ (United States); MacDonald, R. [US Dept. of Agriculture (USDA)., Agricultural Research Service, Phoenix, AZ (United States); Pros, H. [US Dept. of Agriculture (USDA)., Agricultural Research Service, Phoenix, AZ (United States); Martinez, J. [US Dept. of Agriculture (USDA)., Agricultural Research Service, Phoenix, AZ (United States); Sepanski, R. J. [Univ. of Tennessee, Knoxville, TN (United States)

1992-01-01

This NDP presents data on the effects of continuous CO2 enrichment of cotton during five consecutive growing seasons, 1983 to 1987, under both optimal and limiting levels of water and nitrogen. Unlike many prior CO2-enrichment experiments in growth chambers or greenhouses, these studies were conducted on field-planted cotton at close to natural conditions with open-top chambers. Measurements were made on a variety of crop-response variables during the growing season and upon crop harvest. The initial experiment examined the effects of varying CO2 concentration only. During the following two seasons, the interactive effects of CO2 concentration and water availability were studied. During the final two seasons, the interactions among CO2 concentration, water availability, and nitrogen fertility were investigated.

The role and fate of inorganic nitrogen species during UVA/TiO₂ disinfection.

PubMed

Zuo, XiaoJun; Hu, Jiangyong; Chen, MinDong

2015-09-01

Inorganic nitrogen species have three states including ammonia nitrogen (NH4(+)/NH3), nitrite (NO2(-)) and nitrate (NO3(-)) and are often found in the disinfection system. However, no available literature could be found on their role and fate in photocatalytic disinfection systems. In this study, batch experiments were conducted to investigate bacteria inactivation, H2O2 generated and inorganic nitrogen variation to understand the role and fate of inorganic nitrogen species during UVA/TiO2 disinfection and evaluate effects of initial pH and bacteria levels on the role and fate. NH4(+)/NH3 and NO2(-) inhibited the photocatalytic disinfection process obviously. It could be confirmed through that H2O2 yield used for pathogen inactivation was dependent on NH4(+)/NH3 and NO2(-) levels. The NH4(+)/NH3 remaining, NH4(+) remaining and NO3(-) yields in only NH4(+)/NH3 photocatalytic oxidation experiments were obviously different from the corresponding values in the photocatalytic disinfection experiments with NH4(+)/NH3, which confirmed that photocatalytic disinfection had an obvious effect on the fate of NH4(+)/NH3. However, photocatalytic disinfection had slight effects on the fate of NO2(-) and NO3(-). Escherischia coli inactivation rate was the highest in neutral solutions (Initial pH 7) while the lowest in alkaline solutions (Initial pH 8.5). The decrease of NH4(+)/NH3 in alkaline solutions was the most significant. In turn, the photocatalysis of NO2(-) was more evident in acidic solutions. E. coli inactivation was reduced with the increase of initial E. coli concentrations. The initial bacteria concentrations significantly influenced the increase of NH4(+)/NH3, NH4(+) and NO3(-), but slightly impacted the decrease of NO2(-). Copyright © 2015 Elsevier Ltd. All rights reserved.

Benthic fluxes of cadmium, lead, copper and nitrogen species in the northern Adriatic Sea in front of the River Po outflow, Italy.

PubMed

Zago, C; Capodaglio, G; Ceradini, S; Ciceri, G; Abelmoschi, L; Soggia, F; Cescon, P; Scarponi, G

2000-02-10

Trace heavy metal (Cd, Pb and Cu) and nitrogen species (N-NO3, N-NO2 and N-NH4) fluxes between sediment and water were examined for approximately 4 days, in a coastal marine station located in the northern Adriatic Sea in front of the River Po outflow. An in situ benthic chamber, equipped with electronic devices for monitoring and adjustment of oxygen and pH and with a temperature detector, was used. The benthic chamber experiment enabled study of the temporal trend of metals and nutrients when oxygen concentration varied in a controlled environment. Although particular care was devoted to chamber deposition and parameter control, sediment resuspension occurred at the beginning of the experiment and O2 fluctuations were observed during the course of the experiment. Pb concentration was affected by both resuspension and oxic conditions in bottom water, which prevented determination of any reasonable Pb flux value. Cd and Cu, not influenced by oxygen fluctuations, reached an equilibrium phase in a short period with initial positive fluxes from sediment of 0.68 (S.D. = 0.07) and 6.9 (S.D. = 5.6) pmol cm(-2) h(-1), respectively. With regard to nitrogen species, the highest positive flux was that of N-NH4 (10.5, S.D. = 2.4, nmol cm(-2) h(-1)) whose concentration increased in the chamber, while nitrate concentration (initial flux of -5.7, S.D. = 1.5, nmol cm(-2) h(-1)) immediately decreased after the beginning of the experiment. Nitrite concentration was almost constant throughout the experiment and its flux was generally low (initial flux 0.1, S.D. = 0.9, nmol cm(-2) h(-1)).

Temperature-Dependent Kinetic Model for Nitrogen-Limited Wine Fermentations▿

PubMed Central

Coleman, Matthew C.; Fish, Russell; Block, David E.

2007-01-01

A physical and mathematical model for wine fermentation kinetics was adapted to include the influence of temperature, perhaps the most critical factor influencing fermentation kinetics. The model was based on flask-scale white wine fermentations at different temperatures (11 to 35°C) and different initial concentrations of sugar (265 to 300 g/liter) and nitrogen (70 to 350 mg N/liter). The results show that fermentation temperature and inadequate levels of nitrogen will cause stuck or sluggish fermentations. Model parameters representing cell growth rate, sugar utilization rate, and the inactivation rate of cells in the presence of ethanol are highly temperature dependent. All other variables (yield coefficient of cell mass to utilized nitrogen, yield coefficient of ethanol to utilized sugar, Monod constant for nitrogen-limited growth, and Michaelis-Menten-type constant for sugar transport) were determined to vary insignificantly with temperature. The resulting mathematical model accurately predicts the observed wine fermentation kinetics with respect to different temperatures and different initial conditions, including data from fermentations not used for model development. This is the first wine fermentation model that accurately predicts a transition from sluggish to normal to stuck fermentations as temperature increases from 11 to 35°C. Furthermore, this comprehensive model provides insight into combined effects of time, temperature, and ethanol concentration on yeast (Saccharomyces cerevisiae) activity and physiology. PMID:17616615

Controls on the distributions of organic carbon and nitrogen in the eastern Pacific Ocean

NASA Astrophysics Data System (ADS)

Hansell, Dennis A.; Waterhouse, Tye Y.

1997-05-01

Measurements of total organic carbon (TOC) and nitrogen (TON) were made on the WOCE P18 line (from 67°S to 23°N along 103°/110°W). There was an accumulation of TOC on the equator and in the oligotrophic waters north and south of the equator. The concentrations of TOC were well correlated with temperature, indicating an important physical control on its distribution. The boundary separating shallow, TOC-rich water from deep, TOC-poor water overlaid the main thermocline. This observation suggests that water column stability or residence time imparted by the main thermocline is a primary determinant of TOC accumulation. Elevated TON concentrations were found in all surface waters, with the lowest values found in the region of 20-35°S. Net TON drawdown in the South Pacific subtropical gyre, likely due to biological utilization and vertical export of the nitrogen, was initiated with depletion of equatorially upwelled nitrate. The degree to which inorganic nitrogen was limiting in the surface layer south of the equator served to control the concentrations of TON. Such controls were not exerted on organic carbon, as reflected by increasing C:N ratios of organic matter as TON was removed. Unlike the findings in the South Pacific, TON concentrations in oligotrophic waters north of the equator were frequently higher than on the equator. Such accumulations are hypothesized to be maintained from nitrogen fixation, nitrogen input due to vertical migration of autotrophs or diffusive flux of inorganic nitrogen into the euphotic zone across the relatively shallow nitracline.

Nutrient dynamics in two seagrass species, Posidonia coriacea and Zostera tasmanica, on Success Bank, Western Australia

NASA Astrophysics Data System (ADS)

Walker, D. I.; Campey, M. L.; Kendrick, G. A.

2004-06-01

Nutrient concentrations and seasonal differences in atomic ratios (N:P) in plant tissue of Posidonia coriacea Kuo and Cambridge and Zostera tasmanica Aschers (formerly Heterozostera tasmanica (Syst Bot 27 (2002) 468) were measured from multiple locations on Success Bank, southwestern Australia, and used to infer nutritional constraints on seagrass vegetative growth, particularly by phosphorus. Posidonia plant tissue at the west site had higher nitrogen than the east site in both summer and winter. Nitrogen concentrations increased in winter, particularly in sheath tissue, but there was little change in root nitrogen concentrations between sites or seasons. Nitrogen concentrations of leaf tissue were all less than median seagrass values reported by Duarte (Mar Ecol Prog Ser 67 (1990) 201). The seasonality in nutrient concentrations in plant tissues suggests greater nutritional constraints in summer, during periods of high growth. Vegetative growth of Posidonia coriacea was more nutrient limited than that of Zostera tasmanica. Translocation of nutrients along rhizomes to the apex may ensure that growing points are not nutrient limited and that growth can be maintained, and was more apparent in Z. tasmanica than P. coriacea. Sexual reproduction placed large demands on P. coriacea through the high investment of nutrients into fruit, resulting in reduced nutritional constraints on successful seedling recruitment by initially providing seedlings with nutrients.

Purging of a tank-mounted multilayer insulation system by gas diffusion

NASA Technical Reports Server (NTRS)

Sumner, I. E.

1978-01-01

The investigation was conducted on a multilayer insulation (MLI) system mounted on a spherical liquid hydrogen propellant tank. The MLI consisted of two blankets of insulation each containing 15 double-aluminized Mylar radiation shields separated by double silk net spacers. The gaseous nitrogen initially contained within the MLI system and vacuum chamber was purged with gaseous helium introduced both underneath the MLI and into the vacuum chamber. The MLI panels were assumed to be purged primarily by means of gas diffusion. Overall, test results indicated that nitrogen concentrations well below 1 percent could be achieved everywhere within the MLI system. Typical times to achieve 1 percent nitrogen concentration within the MLI panels ranged from 69 minutes at the top of the tank to 158 minutes at the bottom of the tank. Four space-hold thermal performance tests indicated no significant thermal degradation of the MLI system had occurred due to the purge tests conducted. The final measured heat input attributed to the MLI was 7.23 watts as compared to 7.18 watts for the initial baseline thermal performance test.

Modeling Nitrogen Decrease in Water Lettuce Ponds from Waste Stabilization Ponds

NASA Astrophysics Data System (ADS)

Putri, Gitta Agnes; Sunarsih

2018-02-01

This paper presents about the dynamic modeling of the Water Lettuce ponds as a form of improvement from the Water Hyacinth ponds. The purpose of this paper is to predict nitrogen decrease and nitrogen transformation in Water Lettuce ponds integrated with Waste Stabilization Ponds. The model consists of 4 mass balances, namely Dissolved Organic Nitrogen (DON), Particulate Organic Nitrogen (PON), ammonium (NH4+), Nitrate and Nitrite (NOx). The process of nitrogen transformation which considered in a Water Lettuce ponds, namely hydrolysis, mineralization, nitrification, denitrification, plant and bacterial uptake processes. Numerical simulations are performed by giving the values of parameters and the initial values of nitrogen compounds based on a review of previous studies. Numerical results show that the rate of change in the concentration of nitrogen compounds in the integration ponds of waste stabilization and water lettuce decreases and reaches stable at different times.

Fertiliser management effects on dissolved inorganic nitrogen in runoff from Australian sugarcane farms.

PubMed

Fraser, Grant; Rohde, Ken; Silburn, Mark

2017-08-01

Dissolved inorganic nitrogen (DIN) movement from Australian sugarcane farms is believed to be a major cause of crown-of-thorns starfish outbreaks which have reduced the Great Barrier Reef coral cover by ~21% (1985-2012). We develop a daily model of DIN concentration in runoff based on >200 field monitored runoff events. Runoff DIN concentrations were related to nitrogen fertiliser application rates and decreased after application with time and cumulative rainfall. Runoff after liquid fertiliser applications had higher initial DIN concentrations, though these concentrations diminished more rapidly in comparison to granular fertiliser applications. The model was validated using an independent field dataset and provided reasonable estimates of runoff DIN concentrations based on a number of modelling efficiency score results. The runoff DIN concentration model was combined with a water balance cropping model to investigate temporal aspects of sugarcane fertiliser management. Nitrogen fertiliser application in December (start of wet season) had the highest risk of DIN movement, and this was further exacerbated in years with a climate forecast for 'wet' seasonal conditions. The potential utility of a climate forecasting system to predict forthcoming wet months and hence DIN loss risk is demonstrated. Earlier fertiliser application or reducing fertiliser application rates in seasons with a wet climate forecast may markedly reduce runoff DIN loads; however, it is recommended that these findings be tested at a broader scale.

Impact of initial lipid content and oxygen supply on alcoholic fermentation in champagne-like musts.

PubMed

Ochando, Thomas; Mouret, Jean-Roch; Humbert-Goffard, Anne; Sablayrolles, Jean-Marie; Farines, Vincent

2017-08-01

Available nitrogen, lipids, or oxygen are nutrients with major impact on the kinetics of winemaking fermentation. Assimilable nitrogen is usually the growth-limiting nutrient which availability determines the fermentation rate and therefore the fermentation duration. In some particular cases, as in Champagne, grape musts have high available nitrogen content and low turbidity, i.e., below 50 Nephelometric Turbidity Unit (NTU). In the case of low turbidity, the availability of lipids, particularly phytosterols, becomes limiting. In this situation, control of oxygenation, which is necessary for lipid synthesis by yeast, is particularly crucial during fermentation. To mimic and understand these situations, a synthetic medium simulating the average composition of a Champagne must was used. This medium contained phytosterol (mainly β-sitosterol) concentrations ranging from 0 to 8mg/L corresponding to turbidity between 10 and 90 NTU. Population reached during the stationary phase and the maximum fermentation rate are conditioned by the initial phytosterol concentration determining the amount of nitrogen consumption. An early loss of viability was observed when the lipid concentrations were very low. For example, the viability continuously decreased during the stationary phase to a final value of 50% for an initial phytosterol concentration of 1mg/L. In some fermentations, 10mg/L oxygen were added at the end of the growth phase to combine the effects of initial content of phytosterols in the musts and the de novo synthesis of ergosterol and unsaturated fatty acids induced by oxygen addition. Effect of oxygen supply on the fermentation kinetics was particularly significant for media with low phytosterol contents. For example, the maximum fermentation rate was increased by 1.4-fold and the fermentation time was 70h shorter with oxygen addition in the medium containing 2mg/L of phytosterols. As a consequence of the oxygen supply, for the media containing 3, 5 and 8mg/L of phytosterols, the assimilable nitrogen was completely exhausted and the fermentation kinetics, as well as the final populations and viabilities (greater than 90%), were identical for the 3 conditions. The impacts of the lipid content and additional oxygen on acetate, glycerol and succinate synthesis were also studied. The phytosterols decreased the acetate and increased the succinate synthesis, and oxygenation resulted in a decrease in succinate formation. This work highlights the similarities and differences between the effects of lipids and oxygen on fermentation kinetics and yeast metabolism. This research highlights the need for an optimal combined management of lipid content in the must via turbidity and oxygenation, particularly in nitrogen-rich musts. Copyright © 2016 Elsevier Ltd. All rights reserved.

Spatially and Temporally Resolved Atomic Oxygen Measurements in Short Pulse Discharges by Two Photon Laser Induced Fluorescence

NASA Astrophysics Data System (ADS)

Lempert, Walter; Uddi, Mruthunjaya; Mintusov, Eugene; Jiang, Naibo; Adamovich, Igor

2007-10-01

Two Photon Laser Induced Fluorescence (TALIF) is used to measure time-dependent absolute oxygen atom concentrations in O2/He, O2/N2, and CH4/air plasmas produced with a 20 nanosecond duration, 20 kV pulsed discharge at 10 Hz repetition rate. Xenon calibrated spectra show that a single discharge pulse creates initial oxygen dissociation fraction of ˜0.0005 for air like mixtures at 40-60 torr total pressure. Peak O atom concentration is a factor of approximately two lower in fuel lean (φ=0.5) methane/air mixtures. In helium buffer, the initially formed atomic oxygen decays monotonically, with decay time consistent with formation of ozone. In all nitrogen containing mixtures, atomic oxygen concentrations are found to initially increase, for time scales on the order of 10-100 microseconds, due presumably to additional O2 dissociation caused by collisions with electronically excited nitrogen. Further evidence of the role of metastable N2 is demonstrated from time-dependent N2 2^nd Positive and NO Gamma band emission spectroscopy. Comparisons with modeling predictions show qualitative, but not quantitative, agreement with the experimental data.

Research of Isolation and Degradation Conditions of Petroleum Degrading Marine

NASA Astrophysics Data System (ADS)

Fangrui, Guo

2017-01-01

A novel petroleum-degrading microbial strain was isolated from sediment samples in estuary of Bohai Sea estuary beaches. The strain was primarily identified as Alcanivorax sp. and named Alcanivorax sp. H34. Effect of PH values, temperature, nitrogen and phosphorus concentrations on degradation of H34 were investigated. The paraffinic components average degradation rate of H34 ungrowth cells under optimized conditions was studied. The results showed that the optimal growth conditions of H34 are were temperature of 30°C, initial PH of 7.0, nitrogen concentration of 3g/L, phosphorus concentration of 3g/L, and paraffinic components average degradation rates of H34 ungrowth cells was 41.6%, while total degradation rate was 45.5%.

Identification of carbohydrates as the major carbon sink of the marine microalga Isochrysis zhangjiangensis (Haptophyta) and optimization of its productivity by nitrogen manipulation.

PubMed

Wang, Hai-Tao; Yao, Chang-Hong; Ai, Jiang-Ning; Cao, Xu-Peng; Xue, Song; Wang, Wei-liang

2014-11-01

Microalgae represent a potential feedstock for biofuel production. During cultivation under nitrogen-depleted conditions, carbohydrates, rather than neutral lipids, were the major carbon sink of the marine microalga Isochrysis zhangjiangensis (Haptophyta). Carbohydrates reached maximum levels of 21.2 pg cell(-1) on day 5, which was an increase of more than 7-fold from day 1, while neutral lipids simultaneously increased 1.9-fold from 4.0 to 7.6 pg cell(-1) during the ten-day nitrogen-depleted cultivation. The carbohydrate productivity of I. zhangjiangensis was improved by optimization of the nitrate supply mode. The maximum carbohydrate concentration was 0.95 g L(-1) under batch cultivation, with an initial nitrogen concentration of 31.0 mg L(-1), which was 2.4-fold greater than that achieved under nitrogen-depleted conditions. High performance liquid chromatography (HPLC) analysis showed that the accumulated carbohydrate in I. zhangjiangensis was composed of glucose. These results show that I. zhangjiangensis represents an ideal carbohydrate-enriched bioresource for biofuel production. Copyright © 2014 Elsevier Ltd. All rights reserved.

Chronic nitrogen deposition influences the chemical dynamics ...

EPA Pesticide Factsheets

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

Methanol Droplet Extinction in Oxygen/Carbon-dioxide/Nitrogen Mixtures in Microgravity: Results from the International Space Station Experiments

NASA Technical Reports Server (NTRS)

Nayagam, Vedha; Dietrich, Daniel L.; Ferkul, Paul V.; Hicks, Michael C.; Williams, Forman A.

2012-01-01

Motivated by the need to understand the flammability limits of condensed-phase fuels in microgravity, isolated single droplet combustion experiments were carried out in the Combustion Integrated Rack Facility onboard the International Space Station. Experimental observations of methanol droplet combustion and extinction in oxygen/carbon-dioxide/nitrogen mixtures at 0.7 and 1 atmospheric pressure in quiescent microgravity environment are reported for initial droplet diameters varying between 2 mm to 4 mm in this study.The ambient oxygen concentration was systematically lowered from test to test so as to approach the limiting oxygen index (LOI) at fixed ambient pressure. At one atmosphere pressure, ignition and some burning were observed for an oxygen concentration of 13% with the rest being nitrogen. In addition, measured droplet burning rates, flame stand-off ratios, and extinction diameters are presented for varying concentrations of oxygen and diluents. Simplified theoretical models are presented to explain the observed variations in extinction diameter and flame stand-off ratios.

Tribological characteristics of nitrogen (N+) implanted iron

NASA Technical Reports Server (NTRS)

Jones, W. R.; Ferrante, J.

1982-01-01

The effect of implantation of nitrogen ions (1.5 MeV) on the friction and wear characteristics of pure ion sliding against M-50 steel (unimplanted) was studied in a pin-on-disk sliding friction apparatus. Test conditions included room temperature (25 C), a dry air atmosphere, a load of 1/2 kg (4.9 N), sliding velocities of 0.043 to 0.078 m/sec (15 to 25 rpm), a pure hydrocarbon lubricant (n-hexadecane), or a U.S.P. mineral oil and nitrogen ion implantation doses of 5x10 to the 15th power and 5x10 to the 17th power ions/sq cm. No differences in wear rates were observed in the low dose experiments. In the high dose experiments, small reductions in initial (40 percent) and steady state (20 percent) wear rates were observed for nitrogen implanted iron riders as compared with unimplanted controls. No differences in average friction coefficients were noted for either dose. Auger electron spectroscopy combined with argon ion bombardment revealed a subsurface Gaussian nitrogen distribution with a maximum concentration of 6 atomic percent at a depth of 0.8 microns. Similar analysis within the wear scar of an implanted rider after 20 microns of wear yielded only background nitrogen concentration. No inward migration of nitrogen ions was observed.

Study of various NH4+/NO3- mixtures for enhancing growth of potatoes

NASA Technical Reports Server (NTRS)

Cao, W.; Tibbitts, T. W.

1993-01-01

Two experiments were conducted to determine the effects of various NH4(+)-N/NO3(-)-N percentages on growth and mineral concentrations in potato (Solanum tuberosum L.) plants using a non-recirculating nutrient film system in a controlled environment. The first experiment included six NH4(+)-N/NO3(-)-N percentages at 0/100, 20/80, 40/60, 60/40, 80/20, and 100/0 with the same total N concentration of 4 mM. The second experiment included six NH4(+)-N/NO3(-)-N percentages at 0/100, 4/96, 8/92, 12/88, 16/84, and 20/80 again with the same total N of 4 mM. In each experiment, plants were harvested 35 days after transplanting when tubers had been initiated and started to enlarge. Dry weights of shoots, tubers, and whole plant at the harvest were increased significantly with all mixed nitrogen treatments as compared with single NH4+ or NO3- form. The enhanced growth with mixed nitrogen was greatest at 8% to 20% NH4(+)-N. Also, the concentrations and accumulation of total N in the shoots and roots were greater with mixed nitrogen than with separate NH4+ or NO3- nutrition. With NH4+ present in the solutions, the concentrations of P and Cl in the shoots were increased compared to NO3- alone, whereas the tissue concentrations of Ca and Mg were decreased. It was concluded that nitrogen fertilization provided with combined NH4+ and NO3- forms, even at small proportions of NH4+, can enhance nitrogen uptake and productivity in potato plants.

A graphical modeling tool for evaluating nitrogen loading to and nitrate transport in ground water in the mid-Snake region, south-central Idaho

USGS Publications Warehouse

Clark, David W.; Skinner, Kenneth D.; Pollock, David W.

2006-01-01

A flow and transport model was created with a graphical user interface to simplify the evaluation of nitrogen loading and nitrate transport in the mid-Snake region in south-central Idaho. This model and interface package, the Snake River Nitrate Scenario Simulator, uses the U.S. Geological Survey's MODFLOW 2000 and MOC3D models. The interface, which is enabled for use with geographic information systems (GIS), was created using ESRI's royalty-free MapObjects LT software. The interface lets users view initial nitrogen-loading conditions (representing conditions as of 1998), alter the nitrogen loading within selected zones by specifying a multiplication factor and applying it to the initial condition, run the flow and transport model, and view a graphical representation of the modeling results. The flow and transport model of the Snake River Nitrate Scenario Simulator was created by rediscretizing and recalibrating a clipped portion of an existing regional flow model. The new subregional model was recalibrated with newly available water-level data and spring and ground-water nitrate concentration data for the study area. An updated nitrogen input GIS layer controls the application of nitrogen to the flow and transport model. Users can alter the nitrogen application to the flow and transport model by altering the nitrogen load in predefined spatial zones contained within similar political, hydrologic, and size-constrained boundaries.

Sugar Regulation of Plastid Interconversions in Epicarp of Citrus Fruit 1

PubMed Central

Huff, Albert

1984-01-01

Seasonal transformations between chloroplasts and chromoplasts, as measured by changes in chlorophyll content, in the epicarp of degreening and regreening Citrus sinensis (L.) Osbeck cv Valencia fruit closely parallelled the accumulation and later loss of soluble sugars. At any stage of development, reversing the relative soluble sugar content in the epicarp by culturing pericarp segments on agar media with low (15 millimolar) or high (150 millimolar) sucrose concentrations reversed the direction of change in chlorophyll content. Fruit of C. madurensis Lour., which mature year around and do not regreen, also accumulated soluble sugars in the pericarp as degreening was initiated. The epicarp of C. sinensis fruit accumulated nitrogen, but total nitrogen concentrations and amino acid concentrations changed little, during degreening and regreening of C. sinensis fruit. Cessation of nitrogen fertilization reduced the tendency of pericarp segments to regreen in vitro during subsequent years, but regreening tendency was restored by inclusion of KNO3 in the media. It is concluded that chloroplasts become chromoplasts and citrus fruit degreen partially in response to the accumulation of sugars in the epicarp and that the reverse transformation accompanying regreening of certain citrus species occurs when accumulated sugars disappear. Change in nitrogen flux to the fruit is probably not a factor in regulating seasonal transformations, but an abundance of nitrogen in the epicarp diminishes the effects of high sugar concentrations in inducing transformation of chloroplasts to chromoplasts, thereby retarding degreening and promoting regreening. PMID:16663837

The effects of apple pomace, bentonite and calcium superphosphate on swine manure aerobic composting.

PubMed

Jiang, Jishao; Huang, Yimei; Liu, Xueling; Huang, Hua

2014-09-01

The effects of additives such as apple pomace, bentonite and calcium superphosphate on swine manure composting were investigated in a self-built aerated static box (90 L) by assessing their influences on the transformation of nitrogen, carbon, phosphorous and compost maturity. The results showed that additives all prolonged the thermophilic stage in composting compared to control. Nitrogen losses amounted to 34-58% of the initial nitrogen, in which ammonia volatilization accounted for 0.3-4.6%. Calcium superphosphate was helpful in facilitating composting process as it significantly reduced the ammonia volatilization during thermophilic stage and increased the contents of total nitrogen and phosphorous in compost, but bentonite increased the ammonia volatilization and reduced the total nitrogen concentration. It suggested that calcium superphosphate is an effective additive for keeping nitrogen during swine manure composting. Copyright © 2014 Elsevier Ltd. All rights reserved.

Relationship between Fungal Biomass Production and the Brightening of Hardwood Kraft Pulp by Coriolus versicolor

PubMed Central

Kirkpatrick, Neil; Reid, Ian D.; Ziomek, Edmund; Ho, Christopher; Paice, Michael G.

1989-01-01

The white-rot fungus Coriolus versicolor increased the brightness of hardwood kraft pulp by two mechanisms depending on the concentration of available nitrogen. In low-nitrogen conditions, the brightening process was a chemical effect mediated by the fungus, associated with the removal of residual lignin in the pulp; kappa number was used as an indicator of lignin concentration. A five-day treatment in low-nitrogen conditions increased the brightness of hardwood kraft pulp from 36.2 to 54.5%, with a corresponding decrease in kappa number from 12.0 to 8.5, equivalent to a reduction in the lignin concentration from ca. 2.0% (wt/wt) to ca. 1.4% (wt/wt). Under these conditions, we concluded that the brightening of the pulp was a secondary metabolic event initiated after the depletion of available nitrogen. This method of brightening has been described as bleaching or biobleaching. By contrast, in high-nitrogen conditions, the brightening was a physical effect associated with the dilution of the dark pulp fibers by the relatively high levels of brighter fungal mycelium produced. Since this method of brightening was not evidently associated with lignin removal, it cannot be described as bleaching. In pulp samples brightened in high-nitrogen conditions, as brightness increased, there was a corresponding increase in kappa number. This observation was explained by the consumption of potassium permanganate by the fungal mycelium, which interfered with kappa number determinations at high fungal biomass levels. PMID:16347907

40 CFR 439.1 - General definitions.

Code of Federal Regulations, 2013 CFR

2013-07-01

... a POTW treatment system to oxidize ammonia or ammonium salts initially to nitrites (via Nitrosomonas bacteria) and subsequently to nitrates (via Nitrobacter bacteria). Criteria for determining the... bacteria; and analyses of the nitrogen balance demonstrating a reduction in the concentration of ammonia or...

40 CFR 439.1 - General definitions.

Code of Federal Regulations, 2012 CFR

2012-07-01

... a POTW treatment system to oxidize ammonia or ammonium salts initially to nitrites (via Nitrosomonas bacteria) and subsequently to nitrates (via Nitrobacter bacteria). Criteria for determining the... bacteria; and analyses of the nitrogen balance demonstrating a reduction in the concentration of ammonia or...

40 CFR 439.1 - General definitions.

Code of Federal Regulations, 2014 CFR

2014-07-01

... a POTW treatment system to oxidize ammonia or ammonium salts initially to nitrites (via Nitrosomonas bacteria) and subsequently to nitrates (via Nitrobacter bacteria). Criteria for determining the... bacteria; and analyses of the nitrogen balance demonstrating a reduction in the concentration of ammonia or...

Study of the kinetics and mechanism of the thermal nitridation of SiO2

NASA Technical Reports Server (NTRS)

Vasquez, R. P.; Madhukar, A.; Grunthaner, F. J.; Naiman, M. L.

1985-01-01

X-ray photoelectron spectroscopy (XPS) has been used to study the nitridation time and temperature dependence of the nitrogen distribution in thermally nitrided SiO2 films. The XPS data show that the maximum nitrogen concentration near the (SiO(x)N(y)/Si interface is initially at the interface, but moves 20-25 A away from the interface with increasing nitridation time. Computer modeling of the kinetic processes involved is carried out and reveals a mechanism in which diffusing species, initially consisting primarily of nitrogen, react with the substrate, followed by formation of the oxygen-rich oxynitride due to reaction of the diffusing oxygen displaced by the slower nitridation of the SiO2. The data are consistent with this mechanism provided the influence of the interfacial strain on the nitridation and oxidation kinetics is explicitly accounted for.

Correlation of seasonal variations in phosphorous and nitrogen species in upper Black Warrior River with duckweed

DOE Office of Scientific and Technical Information (OSTI.GOV)

Gabrielson, F.C. Jr.; Malatino, A.M.; Santa Cruz, G.J.

1980-10-01

Water samples taken throughout the year from a drainage system that had supported giant duckweed blooms were analyzed for nitrogen and phosphorus. Although seasonal separation of the data indicates possible differences within an imppoundment (Bayview Lake), extreme variations make meaningful conclusions difficult. Daily discharge from a large number of points may have masked seasonal differences. Extensive plant mats were present at minimal levels of nitrogen and phosphorus. The growth rate seemed to be governed more by climate than nutrient conditions. Laboratory investigations indicate that giant duckweed can grow under a wide range of nutrient conditions including high heavy metal concentrations.more » Growth rate data show that without a continual input of nutrients, maximum growth rates do not usually continue beyond 14 to 20 days regardless of the initial single element concentration. With a continuous nutrient input, growth would probably only be inhibited by extreme climate conditions.« less

Aerobic and heterotrophic nitrogen removal by Enterobacter cloacae CF-S27 with efficient utilization of hydroxylamine.

PubMed

Padhi, Soumesh Kumar; Tripathy, Swetaleena; Mohanty, Sriprakash; Maiti, Nikhil Kumar

2017-05-01

Heterotrophic bacterium, Enterobacter cloacae CF-S27 exhibited simultaneous nitrification and aerobic denitrification in presence of high concentration of hydroxylamine. With the initial nitrogen concentration of 100mgL -1 h -1 , ammonium, nitrate and nitrite removal efficiencies were 81%, 99.9% and 92.8%, while the corresponding maximum removal rates reached as high as 11.6, 15.1 and 11.2mgL -1 h -1 respectively. Quantitative amplification by real time PCR and enzyme assay demonstrated that hydroxylamine reductase gene (hao) is actively involved in hetrotrophic nitrification and aerobic denitrification process of Enterobacter cloacae CF-S27. PCR primers were designed targeting amplification of hao gene from diversified environmental soil DNA. The strain Enterobacter cloacae CF-S27 significantly maintained the undetectable amount of dissolved nitrogen throughout 60days of zero water exchange fish culture experiment in domestic wastewater. Copyright © 2017 Elsevier Ltd. All rights reserved.

Coupling loss characteristics of runoff-sediment-adsorbed and dissolved nitrogen and phosphorus on bare loess slope.

PubMed

Wu, Lei; Qiao, Shanshan; Peng, Mengling; Ma, Xiaoyi

2018-05-01

Soil and nutrient loss is a common natural phenomenon but it exhibits unclear understanding especially on bare loess soil with variable rainfall intensity and slope gradient, which makes it difficult to design control measures for agricultural diffuse pollution. We employ 30 artificial simulated rainfalls (six rainfall intensities and five slope gradients) to quantify the coupling loss correlation of runoff-sediment-adsorbed and dissolved nitrogen and phosphorus on bare loess slope. Here, we show that effects of rainfall intensity on runoff yield was stronger than slope gradient with prolongation of rainfall duration, and the effect of slope gradient on runoff yield reduced gradually with increased rainfall intensity. But the magnitude of initial sediment yield increased significantly from an average value of 6.98 g at 5° to 36.08 g at 25° with increased slope gradient. The main factor of sediment yield would be changed alternately with the dual increase of slope gradient and rainfall intensity. Dissolved total nitrogen (TN) and dissolved total phosphorus (TP) concentrations both showed significant fluctuations with rainfall intensity and slope gradient, and dissolved TP concentration was far less than dissolved TN. Under the double influences of rainfall intensity and slope gradient, adsorbed TN concentration accounted for 7-82% of TN loss concentration with an average of 58.6% which was the main loss form of soil nitrogen, adsorbed TP concentration accounted for 91.8-98.7% of TP loss concentration with an average of 96.6% which was also the predominant loss pathway of soil phosphorus. Nitrate nitrogen (NO 3 - -N) accounted for 14.59-73.92% of dissolved TN loss, and ammonia nitrogen (NH 4 + -N) accounted for 1.48-18.03%. NO 3 - -N was the main loss pattern of TN in runoff. Correlation between dissolved TN, runoff yield, and rainfall intensity was obvious, and a significant correlation was also found between adsorbed TP, sediment yield, and slope gradient. Our results provide the underlying insights needed to guide the control of nitrogen and phosphorus loss on loess hills.

Effects of nitrogen and phosphorus on anatoxin-a, homoanatoxin-a, dihydroanatoxin-a and dihydrohomoanatoxin-a production by Phormidium autumnale.

PubMed

Heath, Mark W; Wood, Susanna A; Barbieri, Rafael F; Young, Roger G; Ryan, Ken G

2014-12-15

Anatoxins are powerful neuromuscular blocking agents produced by some cyanobacteria. Consumption of anatoxin-producing cyanobacterial mats or the water containing them has been linked to numerous animal poisonings and fatalities worldwide. Despite this health risk, there is a poor understanding of the environmental factors regulating anatoxin production. Non-axenic Phormidium autumnale strain CAWBG557 produces anatoxin-a (ATX), homoanatoxin-a (HTX) and their dihydrogen-derivatives dihydroanatoxin-a (dhATX) and dihydrohomoanatoxin-a (dhHTX). The effects of varying nitrogen and phosphorus concentrations on the production of these four variants were examined in batch monocultures. The anatoxin quota (anatoxin per cell) of all four variants increased up to four fold in the initial growth phase (days 0-9) coinciding with the spread of filaments across the culture vessel during substrate attachment. Dihydroanatoxin-a and dhHTX, accounted for over 60% of the total anatoxin quota in each nitrogen and phosphorus treatment. This suggests they are being internally synthesised and not just derived following cell lysis and environmental degradation. The four anatoxin variants differed in their response to varying nitrogen and phosphorus concentrations. Notably, dhATX quota significantly decreased (P ≤ 0.03) when nitrogen and phosphorus concentrations were elevated (nitrogen = 21 mg L(-1); phosphorus = 3 mg L(-1)), while HTX quota increased when the phosphorus concentrations were reduced (ca. < 0.08 mg L(-1)). This is of concern as HTX has a high toxicity and anatoxin producing P. autumnale blooms in New Zealand usually occur in rivers with low water column dissolved reactive phosphorus. Copyright © 2014. Published by Elsevier Ltd.

Use of continuous monitoring to assess stream nitrate flux and transformation patterns.

PubMed

Jones, Christopher; Kim, Sea-Won; Schilling, Keith

2017-01-01

Delivery of nitrogen from farmed fields to the stream network is an ongoing water quality issue in central North America and other parts of the world. Although fertilization and other farming practices have been refined to produce environmental improvements, stemming loss of nitrogen, especially in the soluble nitrate form, is a problem that has seemingly defied solution. The Iowa Nutrient Reduction Strategy is a policy initiative designed to implement conservation and other farm management practices to produce reductions in nitrate loading. The strategy does not focus on how the streams themselves may or may not be processing nitrogen and reducing downstream loading. We used continuous high-frequency nitrate and discharge monitoring over 3 years at two sites separated by 18 km in a low-order, agricultural stream in eastern Iowa to estimate how nitrogen is processed, and whether or not these processes are reducing downstream loading. We conclude that the upstream to downstream nitrate concentration decline between the two sites was not driven by denitrification. These data also show that nitrate concentrations are closely coupled to discharge during periods of adequate moisture, but decoupling of concentration from discharge occurs during dry periods. This decoupling is a possible indicator of in-stream nitrate processing. Finally, nitrate concentrations are likely diluted by water sourced from non-row crop land covers in the lower reaches of the watershed.

Interaction of initial litter quality and thinning intensity on litter decomposition rate, nitrogen accumulation and release in a pine plantation

Treesearch

Xiao Chen; Deborah Page-Dumroese; Ruiheng Lv; Weiwei Wang; Guolei Li; Yong Liu

2014-01-01

Thinning alters litter quality and microclimate under forests. Both of these two changes after thinning induce alterations of litter decomposition rates and nutrient cycling. However, a possible interaction between these two changes remains unclear. We placed two types of litter (LN, low N concentration litter; HN, high N concentration litter) in a Chinese pine (Pinus...

Two Catalysts for Selective Oxidation of Contaminant Gases

NASA Technical Reports Server (NTRS)

Wright, John D.

2011-01-01

Two catalysts for the selective oxidation of trace amounts of contaminant gases in air have been developed for use aboard the International Space Station. These catalysts might also be useful for reducing concentrations of fumes in terrestrial industrial facilities especially facilities that use halocarbons as solvents, refrigerant liquids, and foaming agents, as well as facilities that generate or utilize ammonia. The first catalyst is of the supported-precious-metal type. This catalyst is highly active for the oxidation of halocarbons, hydrocarbons, and oxygenates at low concentrations in air. This catalyst is more active for the oxidation of hydrocarbons and halocarbons than are competing catalysts developed in recent years. This catalyst completely converts these airborne contaminant gases to carbon dioxide, water, and mineral acids that can be easily removed from the air, and does not make any chlorine gas in the process. The catalyst is thermally stable and is not poisoned by chlorine or fluorine atoms produced on its surface during the destruction of a halocarbon. In addition, the catalyst can selectively oxidize ammonia to nitrogen at a temperature between 200 and 260 C, without making nitrogen oxides, which are toxic. The temperature of 260 C is higher than the operational temperature of any other precious-metal catalyst that can selectively oxidize ammonia. The purpose of the platinum in this catalyst is to oxidize hydrocarbons and to ensure that the oxidation of halocarbons goes to completion. However, the platinum exhibits little or no activity for initiating the destruction of halocarbons. Instead, the attack on the halocarbons is initiated by the support. The support also provides a high surface area for exposure of the platinum. Moreover, the support resists deactivation or destruction by halogens released during the destruction of halocarbons. The second catalyst is of the supported- metal-oxide type. This catalyst can selectively oxidize ammonia to nitrogen at temperatures up to 400 C, without producing nitrogen oxides. This catalyst converts ammonia completely to nitrogen, even when the concentration of ammonia is very low. No other catalyst is known to oxidize ammonia selectively at such a high temperature and low concentration. Both the metal oxide and the support contribute to the activity and selectivity of this catalyst.

Differences on nitrogen availability in a soil amended with fresh, composted and thermally-dried sewage sludge.

PubMed

Tarrasón, D; Ojeda, G; Ortiz, O; Alcañiz, J M

2008-01-01

Anaerobically-digested sludge called fresh sludge (F), composted sludge (C) and thermally-drying sludge (T), all from the same batch, were applied to the surface of a calcareous Udic Calciustept with loamy texture. Dosage equivalent was 10 t ha(-1) of dry matter. The concentration of mineral nitrogen (ammonium and nitrate) in the soil was measured in order to estimate the effects of the post-treatments to which the different kinds of sewage sludge are subjected in relation to the availability of N in the surface layer of the soil. The most significant differences in NH(4)-N and NO(3)-N concentrations due to the transformation of the organic matter were observed during the first three weeks following soil amendment. Thermally-dried and composted sludge initially displayed higher concentrations of ammonium and nitrate in soil. Five months after the amendment, soil applied with fresh sludge showed the highest concentrations of NH(4)-N and NO(3)-N (6.1 and 36.6 mg kg(-1), respectively). It is clear that the processes of composting and thermal-drying influence the bioavailability of nitrogen from the different types of sewage sludge.

Effect of initial total solids concentration on volatile fatty acid production from food waste during anaerobic acidification.

PubMed

Wang, Quan; Jiang, Jianguo; Zhang, Yujing; Li, Kaimin

2015-01-01

The effect of initial total solids (TS) concentration on volatile fatty acid (VFAs) production from food waste under mesophilic conditions (35 °C) was determined. VFAs concentration and composition, biogas production, soluble chemical oxygen demand concentration, TS and volatile solids (VS) reduction, and ammonia nitrogen [Formula: see text] release were investigated. The VFAs concentrations were 26.10, 39.68, 59.58, and 62.64 g COD/L at TS contents of 40, 70, 100, and 130 g/L, respectively. While the VFAs' yields ranged from 0.467 to 0.799 g COD/g VSfed, decreased as initial TS increased. The percentage of propionate was not affected by TS concentration, accounting for 30.19-34.86% of the total VFAs, while a higher percentage of butyrate and lower percentage of acetate was achieved at a higher TS concentration. Biogas included mainly hydrogen and carbon dioxide and the maximum hydrogen yield of 148.9 ml/g VSfed was obtained at 130 g TS/L. [Formula: see text] concentration, TS and VS reductions increased as initial TS increased. Considering the above variables, we conclude that initial TS of 100 g/L shall be the most appropriate to VFAs production.

Co-composting of two-phase olive-mill pomace and poultry manure with tomato harvest stalks.

PubMed

Sülük, Kemal; Tosun, İsmail; Ekinci, Kamil

2017-04-01

In this study, two-phase olive-mill pomace with poultry manure and chopped tomato harvest stalks were composted at different initial carbon/nitrogen (C/N) ratios with fixed free air space of 35%. Composting experiment was carried out in the 15 aerobic reactors made of stainless steel and was monitored for 28 days. During the composting process, temperature, moisture content, organic matter (OM), pH, electrical conductivity, oxygen and carbon dioxide concentrations, total carbon, total nitrogen, ammonium nitrogen ([Formula: see text]), nitrate nitrogen ([Formula: see text]), and total phosphorus were monitored. Compost mass and volume changes were determined at the beginning, during remixings, and at the end of composting. While the stabilization period took less time for the mixtures containing a high amount of poultry manure, the mixtures having the high portion of two-phase olive-mill pomace took a longer time due to the structure of olive stone and its lignin content. Dry matter loss (range: 18.1-34.0%.) in the mixtures increased with an increase in the share of poultry manure and tomato stalks in the initial mixture. OM loss (range: 21.7-46.1%) for tomato stalks (measured separately) during composting increased due to an increase in the ratio of poultry manure in the initial mixtures.

Effect of nitrogen and phosphorus concentration on their removal kinetic in treated urban wastewater by Chlorella vulgaris.

PubMed

Ruiz, J; Alvarez, P; Arbib, Z; Garrido, C; Barragán, J; Perales, J A

2011-10-01

This study evaluates the feasibility of removing nutrients by the microalgae Chlorella vulgaris, using urban wastewater as culture medium, namely the effluent subjected to secondary biological treatment in a wastewater treatment plant (WWTP). For this, laboratory experiments were performed in batch cultures to study the effect of initial nitrogen and phosphorus concentrations on growth and reduction of nutrient performance of C. vulgaris. The microalga was cultivated in enriched wastewater containing different phosphorus (1.3-143.5 mg x L(-1) P.PO4(3-)), ammonium (5.8-226.8 mg x L(-1) N-NH4+) and nitrate (1.5-198.3 mg x L(-1) N-NO3-) concentrations. The nutrient removal and growth kinetics have been studied: maximum productivity of 0.95 g SS x L(-1) x day(-1), minimum yield factor for cells on substrate (Y) of 11.51 g cells x g nitrogen(-1) and 0.04 g cells x g phosphorus(-1) were observed. The results suggested that C. vulgaris has a high potential to reduce nutrients in secondary WWTP effluents.

Isolation and identification of soil fungi isolates from forest soil for flooded soil recovery

NASA Astrophysics Data System (ADS)

Hazwani Aziz, Nor; Zainol, Norazwina

2018-04-01

Soil fungi have been evaluated for their ability in increasing and recovering nitrogen, phosphorus and potassium content in flooded soil and in promoting the growth of the host plant. Host plant was cultivated in a mixture of fertile forest soil (nutrient-rich soil) and simulated flooded soil (nutrient-poor soil) in an optimized soil condition for two weeks. The soil sample was harvested every day until two weeks of planting and was tested for nitrogen, phosphorus and potassium concentration. Soil fungi were isolated by using dilution plating technique and was identified by Biolog’s Microbial Systems. The concentration of nitrogen, phosphorus, and potassium was found to be increasing after two weeks by two to three times approximately from the initial concentration recorded. Two fungi species were identified with probability more than 90% namely Aspergillus aculeatus and Paecilomyces lilacinus. Both identified fungi were found to be beneficial in enhancing plant growth and increasing the availability of nutrient content in the soil and thus recovering the nutrient content in the flooded soil.

Ground-water quality assessment of the Georgia-Florida Coastal Plain study unit; analysis of available information on nutrients, 1972-92

USGS Publications Warehouse

Berndt, M.P.

1996-01-01

The U.S. Geological Survey is conducting an assessment of water quality in the Georgia-Florida Coastal Plain study unit as part of the National Water-Quality Assessment Program. An initial activity of the program is to compile and analyze existing water-quality data for nutrients in each study unit. Ground-water quality data were compiled from three data sources, the U.S. Geological Survey, Florida Department of Environmental Protection, and Georgia Geologic Survey. A total of 2,246 samples of ground water nutrient data for nitrogen and phosphorus species were compiled from these three data sources. Estimates of 1990 nitrogen and phosphorus inputs by county in the study area were calculated from livestock manure, fertilizers, septic tanks, and rainfall. Data for nitrate nitrogen concentrations in ground water were available from the greatest number of wells; samples from 1,233 wells were available in the U.S. Geological Survey, 820 wells from the Florida Department of Environmental Protection, and 680 wells from the Georgia Geologic Survey. The maximum contaminant level for nitrate nitrogen in drinking water of 10 milligrams per liter was exceeded in a higher percentage of samples from the U.S. Geological Survey, mostly because this data contained numerous samples near known contamination areas. The maximum contaminant level for nitrate nitrogen was exceeded in 3 percent of samples from Upper Floridan aquifer and 12 percent of samples from surficial aquifer system in U.S. Geological Survey data and less than 1 percent and 2 percent of samples from the Upper Floridan aquifer and surficial aquifer system, respectively, in Florida Department of Environmental Protection data. In Georgia Geologic Survey data, 1 percent of samples had concentrations of nitrate nitrogen exceeding 10 milligrams per liter. Nutrient concentration data were grouped into categories based on land use, hydrogeology (aquifer and confinement of the Upper Floridan aquifer), and land resource provinces (Central Florida Ridge, Coastal Flatwoods and Southern Coastal Plain) for the surficial aquifer system. The highest median nitrate nitrogen concentrations in the U.S. Geological Survey data were 0.4 milligrams per liter in ground-water samples from the unconfined Upper Floridan aquifer in agricultural areas and 9.0 milligrams per liter in samples from the surficial aquifer system in agricultural areas in the Central Florida Ridge. In Florida Department of Environmental Protection data, the highest median nitrate nitrogen concentrations were much lower and did not exceed 0.2 milligrams per liter in either the Upper Floridan aquifer or the surficial aquifer system. In Georgia Geologic Survey data the highest median nitrate nitrogen concentration was 1.4 milligrams per liter in agricultural areas in the Coastal Flatwoods. Highest median concentrations of total nitrogen of 10 milligrams per liter (includes nitrate, ammonia, and organic nitrogen) were in U.S. Geological Survey data in the surficial aquifer system in agricultural areas in the Central Florida Ridge. Median concentrations of ammonia nitrogen, orthophosphate phosphorus, and total phosphorus did not exceed 0.5 milligrams per liter in all categories from the Upper Floridan aquifer or the surficial aquifer system.

Activated carbon-based magnetic TiO2 photocatalyst codoped with iodine and nitrogen for organic pollution degradation

NASA Astrophysics Data System (ADS)

Wang, Xuejiang; Song, Jingke; Huang, Jiayu; Zhang, Jing; Wang, Xin; Ma, RongRong; Wang, Jiayi; Zhao, Jianfu

2016-12-01

Magnetic photocatalyst - iodine and nitrogen codoped TiO2 based on chitosan decorated magnetic activated carbon (I-N-T/CMAC) was prepared via simple coprecipitation and sol-gel method. The characteristics of photocatalysts were investigated by X-ray diffraction (XRD), N2 adsorption-desorption isotherm, field emission scanning electron microscopy (FESEM), energy dispersive spectrometry (EDS), fourier transform infrared (FTIR), X-ray photoelectron spectroscopy (XPS), UV-vis diffuse reflection spectroscopy (UV-vis DRS), photoluminescence (PL) spectroscopy and vibrating sample magnetometer (VSM). It turned out that the prepared material had large surface area, enhanced absorption of visible light, and magnetically separable properties when mole ratio of I/Ti was 0.1. Iodine-nitrogen codoped magnetic photocatalyst was used for the removal of salicylic acid (SA), and the rate of adsorption reaction for SA by I0.1-N-T/CMAC followed the pseudo second-order kinetic. Under visible light irradiation, 89.71% SA with initial concentration = 30 mg/L could be removed by I0.1-N-T/CMAC, and photodegradation rate of SA on I0.1-N-T/CMAC composites was 0.0084 min-1 which is about 4 times higher than that of magnetic photocatalyst with nitrogen doped only. The effects of SA initial concentration, pH, coexisting anions and humic acid to the degradation of SA with the prepared material were also investigated. Main oxidative species in the photodegradation process are rad OH and h+.

Effect of nitrogen regime on microalgal lipid production during mixotrophic growth with glycerol.

PubMed

Paranjape, Kiran; Leite, Gustavo B; Hallenbeck, Patrick C

2016-08-01

Mixotrophic growth of microalgae to boost lipid production is currently under active investigation. Such a process could be of practical importance if a cheap source of organic carbon, such as waste glycerol from biodiesel production, could be used. Several previous studies have already demonstrated that this carbon source can be used by different indigenous strains of microalgae. In this study it is shown that different nitrogen limitation strategies can be applied to further increase lipid production during growth with glycerol. In one strategy, cultures were grown in nitrogen replete medium and then resuspended in nitrogen free medium. In a second strategy, cultures were grown with different initial concentrations of nitrate. Lipid production by the two microalgal strains used, Chlorella sorokiniana (PCH02) and Chlorella vulgaris (PCH05), was shown to be boosted by strategies of nitrogen limitation, but they responded differently to how nitrogen limitation was imposed. Copyright © 2016 Elsevier Ltd. All rights reserved.

Conversion of fogwater and aerosol organic nitrogen to ammonium, nitrate, and NOx during exposure to simulated sunlight and ozone.

PubMed

Zhang, Qi; Anastasio, Cort

2003-08-15

Although organic nitrogen (ON) compounds are apparently ubiquitous in the troposphere, very little is known about their fate and transformations. As one step in addressing this issue, we have studied the transformations of bulk (uncharacterized) organic nitrogen in fogwaters and aerosol aqueous extracts during exposure to simulated sunlight and O3. Our results show that over the course of several hours of exposure a significant portion of condensed-phase organic nitrogen is transformed into ammonium, nitrite, nitrate, and NOx. For nitrite, there was both photochemical formation and destruction, resulting in a slow net loss. Ammonium and nitrate were formed at initial rates on the order of a few micromolar per hour in the bulk fogwaters, corresponding to formation rates of approximately 10 and 40 ng m(-3) h(-1), respectively, in ambient fog. The average initial formation rate (expressed as ng (m of air)(-3) h(-1)) of NH4+ in the aqueous extracts of fine particles (PM2.5) was approximately one-half of the corresponding fogwater value. Initial formation rates of NOx (i.e., NO + NO2) were equivalent to approximately 2-11 pptv h(-1) in the three fogwaters tested. Although the formation rates of ammonium and nitrate were relatively small as compared to their initial concentrations in fogwaters (approximately 200-2000 microM) and aerosol particles (approximately 400-1500 ng m(-3)), this photochemical mineralization and "renoxification" from condensed-phase organic N is a previously uncharacterized source of inorganic N in the atmosphere. This conversion also represents a new component in the biogeochemical cycle of nitrogen that might have significant influences on atmospheric composition, condensed-phase properties, and the ecological impacts of N deposition.

Production of fermentation aroma compounds by Saccharomyces cerevisiae wine yeasts: effects of yeast assimilable nitrogen on two model strains.

PubMed

Carrau, Francisco M; Medina, Karina; Farina, Laura; Boido, Eduardo; Henschke, Paul A; Dellacassa, Eduardo

2008-11-01

The contribution of yeast fermentation metabolites to the aromatic profile of wine is well documented; however, the biotechnological application of this knowledge, apart from strain selection, is still rather limited and often contradictory. Understanding and modeling the relationship between nutrient availability and the production of desirable aroma compounds by different strains must be one of the main objectives in the selection of industrial yeasts for the beverage and food industry. In order to overcome the variability in the composition of grape juices, we have used a chemically defined model medium for studying yeast physiological behavior and metabolite production in response to nitrogen supplementation so as to identify an appropriate yeast assimilable nitrogen level for strain differentiation. At low initial nitrogen concentrations, strain KU1 produced higher quantities of esters and fatty acids whereas M522 produced higher concentrations of isoacids, gamma-butyrolactone, higher alcohols and 3-methylthio-1-propanol. We propose that although strains KU1 and M522 have a similar nitrogen consumption profile, they represent useful models for the chemical characterization of wine strains in relation to wine quality. The differential production of aroma compounds by the two strains is discussed in relation to their capacity for nitrogen usage and their impact on winemaking. The results obtained here will help to develop targeted metabolic footprinting methods for the discrimination of industrial yeasts.

Detailed mechanism of benzene oxidation

NASA Technical Reports Server (NTRS)

Bittker, David A.

1987-01-01

A detailed quantitative mechanism for the oxidation of benzene in both argon and nitrogen diluted systems is presented. Computed ignition delay time for argon diluted mixtures are in satisfactory agreement with experimental results for a wide range of initial conditions. An experimental temperature versus time profile for a nitrogen diluted oxidation was accurately matched and several concentration profiles were matched qualitatively. Application of sensitivity analysis has given approximate rate constant expressions for the two dominant heat release reactions, the oxidation of C6H5 and C5H5 radicals by molecular oxygen.

Ammonia-nitrogen sorptional properties of banana peels.

PubMed

Chen, Yunnen; Ding, Lichao; Fan, Jingbiao

2011-04-01

Using modified banana peel as a biosorbent to treat water containing ammonia-nitrogen (NH4(+)-N) was studied. Related parameters in the sorptional process, such as chemical modification, pH, and contact time were investigated. The experimental results showed that banana peel modified by 30% sodium hydroxide (NaOH) and mesothermal microwaves (NMBPs) can greatly improve the sorption removal for NH4(+)-N. The kinetics study revealed that the sorption behavior better fit the pseudo-second-order equation than the Lagergren first-order equation. Fourier transform infrared absorption spectrum analysis of banana peels and NMBPs before and after NH4(+)-N sorption revealed that the activity of hydroxyl groups at the surface of the banana peels was strengthened after modification, and nitrogenous groups appeared after biosorpting the NH4(+)-N. In the end, metallurgical wastewater containing a low concentration of NH4(+)-N was treated by NMBPs. The initial NH4(+)-N concentration of 138 mg/L was reduced to 13 mg/L in 25 minutes by 4 g/L NMBPs at pH 10.

NITROGEN CONCENTRATION OF STOMACH CONTENTS AS AN INDEX OF DIETARY NITROGEN FOR HISPID COTTON RATS

EPA Science Inventory

We examined the reliability of using nitrogen concentration of stomach contents from hispid cotton rats (Sigmodon hispidus) as an index of diet nitrogen. Stomach contents of cotton rats fed diets varying in nitrogen concentration were analyzed for stomach nitrogen. Regression a...

NITROGEN CONCENTRATION OF STOMACH CONTENTS AS AN INDEX OF DIETARY NITROGEN FOR HISPID COTTON RATS (SIGMODON HISPIDUS)

EPA Science Inventory

We examined the reliability of using nitrogen concentration of stomach contents from hispid cotton rats (Sigmodon hispidus) as an index of diet nitrogen. Stomach contents of cotton rats fed diets varying in nitrogen concentration were analyzed for stomach nitrogen. Regression a...

Water-quality and amphibian population data for Maryland, Washington, D.C., and Virginia, 2001-2004

USGS Publications Warehouse

Rice, K.C.; Jung, R.E.

2004-01-01

Data on the chemical composition of water and on amphibian populations were collected at least annually from vernal pool and stream sites in Maryland, Washington, D.C., and Virginia, from 2001 through 2004. The data were collected as part of long-term monitoring projects of the Northeast Region of the Amphibian Research and Monitoring Initiative (ARMI) of the U.S. Geological Survey. Water samples were analyzed for temperature, specific conductance, pH, dissolved-oxygen concentration, acid-neutralizing capacity, and concentrations of total Kjeldahl nitrogen and total phosphorus; in 2004, samples also were analyzed for nitrite plus nitrate concentrations and total nitrogen concentrations. Field and laboratory analytical results of water samples and quality-assurance information are presented. Amphibian population data include the presence of amphibian species and the maximum number of egg masses of wood frogs and spotted salamanders at vernal pools, and counts of amphibians made during stream transect and stream quadrat surveys.

Contribution of ozone to airborne aldehyde formation in Paris homes.

PubMed

Rancière, Fanny; Dassonville, Claire; Roda, Célina; Laurent, Anne-Marie; Le Moullec, Yvon; Momas, Isabelle

2011-09-15

Indoor aldehydes may result from ozone-initiated chemistry, mainly documented by experimental studies. As part of an environmental investigation included in the PARIS birth cohort, the aim of this study was to examine ozone contribution to airborne aldehyde formation in Paris homes. Formaldehyde, acetaldehyde and hexaldehyde levels, as well as styrene, nitrogen dioxide and nicotine concentrations, comfort parameters and carbon dioxide levels, were measured twice during the first year of life of the babies. Ambient ozone concentrations were collected from the closest background station of the regional air monitoring network. Traffic-related nitrogen oxide concentrations in front of the dwellings were estimated by an air pollution dispersion model. Home characteristics and families' way of life were described by questionnaires. Stepwise multiple linear regression models were used to link aldehyde levels with ambient ozone concentrations and a few aldehyde precursors involved in oxidation reactions, adjusting for other indoor aldehyde sources, comfort parameters and traffic-related nitrogen oxides. A 4 and 11% increase in formaldehyde and hexaldehyde levels was pointed out when 8-hour ozone concentrations increased by 20 μg/m(3). The influence of potential precursors such as indoor styrene level and frequent use of air fresheners, containing unsaturated volatile organic compounds as terpenes, was also found. Thus, our results suggest that ambient ozone can significantly impact indoor air quality, especially with regard to formaldehyde and hexaldehyde levels. Copyright © 2011 Elsevier B.V. All rights reserved.

Laboratory Investigations of Titan Haze Formation: Characterization of Gas Phase and Particle Phase Nitrogen

NASA Astrophysics Data System (ADS)

Horst, Sarah; Yoon, Heidi; Li, Rui; deGouw, Joost; Tolbert, Margaret

2014-11-01

Prior to the arrival of the Cassini-Huygens spacecraft, aerosol production in Titan’s atmosphere was believed to begin in the stratosphere where chemical processes are predominantly initiated by far ultraviolet (FUV) radiation. However, the discovery of very heavy ions, coupled with Cassini Ultraviolet Imaging Spectrograph (UVIS) occultation measurements that show haze absorption up to 1000 km altitude (Liang et al., 2007), indicates that haze formation initiates in the thermosphere. The energy environment of the thermosphere is significantly different from the stratosphere; in particular there is a greater flux of extreme ultraviolet (EUV) photons and energetic particles available to initiate chemical reactions, including the destruction of N2, in the upper atmosphere. The discovery of previously unpredicted nitrogen species in measurements of Titan’s atmosphere by the Cassini Ion and Neutral Mass Spectrometer (INMS) indicates that nitrogen participates in the chemistry to a much greater extent than was appreciated before Cassini (Vuitton et al., 2007). Additionally, measurements obtained by the Aerosol Collector Pyrolyzer (ACP) carried by Huygens to Titan’s surface may indicate that Titan’s aerosols contain significant amounts of nitrogen (Israël et al., 2005, 2006). The degree of nitrogen incorporation in the haze particles is important for understanding the diversity of molecules that may be present in Titan’s atmosphere and on its surface. We have conducted a series of Titan atmosphere simulation experiments using either spark discharge (tesla coil) or FUV photons (deuterium lamp) to initiate chemistry in CH4/N2 gas mixtures ranging from 0.01% CH4/99.99% N2 to 10% CH4/90% N2. We obtained in situ measurements using a high-resolution time-of-flight aerosol mass spectrometer (HR-ToF-AMS) to measure the particle composition as a function of particle size and a proton-transfer ion-trap mass spectrometer (PIT-MS) to measure the composition of gas phase products. These two techniques allow us to investigate the effect of energy source and initial CH4 concentration on the degree of nitrogen incorporation in both the gas and solid phase products.

Hydrogen generation through indirect biophotolysis in batch cultures of the nonheterocystous nitrogen-fixing cyanobacterium Plectonema boryanum.

PubMed

Huesemann, Michael H; Hausmann, Tom S; Carter, Blaine M; Gerschler, Jared J; Benemann, John R

2010-09-01

The nitrogen-fixing nonheterocystous cyanobacterium Plectonema boryanum was used as a model organism to study hydrogen generation by indirect biophotolysis in nitrogen-limited batch cultures that were continuously illuminated and sparged with argon/CO(2) to maintain anaerobiosis. The highest hydrogen-production rate (i.e., 0.18 mL/mg day or 7.3 micromol/mg day) was observed in cultures with an initial medium nitrate concentration of 1 mM at a light intensity of 100 micromol/m(2) s. The addition of photosystem II (PSII) inhibitor 3-(3,4-dichlorophenyl)-1,1-dimethylurea (DCMU) did not reduce hydrogen-production rates relative to unchallenged controls for 50 to 150 h, and intracellular glycogen concentrations decreased significantly during the hydrogen generation period. The insensitivity of the hydrogen-production process to DCMU is indicative of the fact that hydrogen was not derived from water splitting at PSII (i.e., direct biophotolysis) but rather from electrons provided by intracellular glycogen reserves (i.e., indirect biophotolysis). It was shown that hydrogen generation could be sustained for long time periods by subjecting the cultures to alternating cycles of aerobic, nitrogen-limited growth and anaerobic hydrogen production.

Water-quality data at amphibian research sites in Maryland, Washington, D.C., and Virginia, 2005-2007

USGS Publications Warehouse

Rice, Karen C.

2008-01-01

Data on the chemical composition of water were collected at least once from 47 amphibian research sites in Maryland, Washington, D.C., and Virginia, from 2005 through 2007. One hundred twenty-five water samples were collected from vernal pools and streams and analyzed as part of long-term monitoring projects of the U.S. Geological Survey Amphibian Research and Monitoring Initiative in the Northeast Region. Field measurements of water temperature, specific conductance, and pH were made. Laboratory analyses of the water samples included acid-neutralizing capacity, total Kjeldahl nitrogen (ammonium plus organic nitrogen), nitrite plus nitrate, total nitrogen, and total phosphorus concentrations. Field and laboratory analytical results of water samples and quality-assurance data are presented.

Photochemical ozone formation from petroleum refinery emissions

NASA Astrophysics Data System (ADS)

Sexton, Ken; Westberg, Hal

Atmospheric emissions from the Marathon oil refinery at Robinson, Illinois were investigated during June and July 1977. Surface and aerial measurements were used to provide an integrated, three dimensional monitoring network. Concentrations of ozone, oxides of nitrogen, sulfur dioxide, methane, carbon dioxide, individual non-methane hydrocarbons and halocarbons were recorded on a routine basis. In addition, meteorological parameters such as wind speed, wind direction, solar radiation and mixing height were also measured. The field monitoring study focused on three major areas: (1) characterization of gaseous components within the refinery effluent, especially nonmethane hydrocarbons and nitrogen oxides; (2) natural sunlight bag irradiation experiments to examine ozone forming potential of refinery emissions and (3) aerial measurements of changes in plume chemistry during the first six to eight hours of transport. Results indicate levels of hydrocarbons and nitrogen oxides were elevated downwind of the refinery. Concentrations within the effluent exceeded background values by as much as 300- and 10-fold, respectively. Irradiations of captured refinery emissions suggest excess photochemical ozone can be produced in the first 6 h, with amounts varying according to NMHC/NO x, ratios and initial NMHC concentrations. Real-time measurements on board the aircraft documented instances of ozone buildup in the refinery plume as it drifted downwind.

Effect of salinity on the critical nitrogen concentration of Spartina alterniflora Loisel

USGS Publications Warehouse

Bradley, P.M.; Morris, J.T.

1992-01-01

Nitrogen was withheld from the salt marsh grass Spartina alterniflora Loisel., in order to determine the effect of salinity (sea salts) on critical tissue nitrogen concentrations (defined here as the minimum tissue concentration required to sustain biomass accumulation). The critical nitrogen concentration per kilogram dry weight of above-ground tissue increased non-linearly from a mean of 8.2 g kg-1 at 5 g l-1 and 20 g l-1 salinity to 13.6 g kg-1 and 22.9 g kg-1 at salinities of 40 g l-1 and 50 g l-1, respectively. Below-ground tissue nitrogen concentrations averaged 62% of the above-ground values irrespective of salinity treatment. These results suggest that the critical nitrogen concentration is a function of salinity and indicate that the internal nitrogen supply required in support of growth increases with salinity. Above-ground tissue nitrogen concentrations reported in the literature and the relationship between salinity and critical nitrogen concentration observed in this study were used to evaluate the nitrogen status of S. alterniflora over a wide range of geographical locations. Comparisons suggest that both short and tall forms of S. alterniflora are nitrogen limited in the majority of marshes along the Gulf and Atlantic Coasts of the US. ?? 1992.

First flush characteristics of rainfall runoff from a paddy field in the Taihu Lake watershed, China.

PubMed

Li, Songmin; Wang, Xiaoling; Qiao, Bin; Li, Jiansheng; Tu, Jiamin

2017-03-01

Nonpoint storm runoff remains a major threat to surface water quality in China. As a paddy matures, numerous fertilizers are needed, especially in the rainy seasons; the concentration of nitrogen and phosphorus in rainfall runoff from farmland is much higher than at other times, and this poses a great threat to water bodies and is the main reason for water eutrophication, especially in high concentration drainages. To date, most studies regarding the characteristics of pollutants in rainfall runoff have mainly been concentrated on urban runoff and watershed runoff; therefore, it is particularly important to investigate the characteristics of nitrogen and phosphorus loss in rainfall runoff from paddy fields. To study the characteristics of nitrogen and phosphorus loss and whether the first flush effect exists, continuous monitoring of the rainfall runoff process of six rainfall events was conducted in 2013, of which four rainfall events during storm, high, middle, and low intensity rainfalls were analyzed, and runoff and quality parameters, such as suspended solids (SS), total nitrogen (TN), ammonium nitrogen (NH 4 + -N), nitrate nitrogen (NO 3 - -N), total phosphorus (TP), and phosphate (PO 4 3- -P), were analyzed to determine the relationship between runoff and water quality. The paddy field is located north of Wuxi Lake Basin along the Hejia River upstream in Zhoutie town, Yixing city. An analysis of the load distribution during rainfall runoff was conducted. Event mean concentration (EMC) was used to evaluate the pollution situation of the paddy field's rainfall runoff. A curve of the dimensionless normalized cumulative load (L) vs. normalized cumulative flow (F) (L-F curve), the probability of the mass first flush (MFFn), and the pollutants carried by the initial 25% of runoff (FF 25 ) were used to analyze the first flush effect of the paddy field runoff, and different contaminants show different results: the concentration of nitrogen and phosphorus fluctuate and follow a similar trend as runoff changes, NO 3 - -N concentration is lower in the early part of runoff and higher in the later, and TP mainly occurs in the particle state in storm runoff and mainly in the dissolved state when the rainfall intensity is smaller. Nitrogen and phosphorus losses from paddy fields are closely related to the average rainfall intensity and the max rainfall intensity, and the runoff loss of nitrogen and phosphorus is more severe when the rainfall intensity is large. Based on an analysis of multiple methodologies, TN and NH 4 + -N show a certain degree of a first flush effect, whereas the first flush effect of TP is not obvious. The first flush effect of SS is obvious in larger intensity rainfall and shows a slight secondary flush effect in smaller rainfall events.

40 CFR 86.1323-84 - Oxides of nitrogen analyzer calibration.

Code of Federal Regulations, 2012 CFR

2012-07-01

... calibrated, if the deviation from a least-squares best-fit straight line is within ±2 percent of the value at... exceeds these limits, then the best-fit non-linear equation which represents the data within these limits shall be used to determine concentration values. (c) The initial and periodic interference, system check...

40 CFR 86.1323-84 - Oxides of nitrogen analyzer calibration.

Code of Federal Regulations, 2013 CFR

2013-07-01

... calibrated, if the deviation from a least-squares best-fit straight line is within ±2 percent of the value at... exceeds these limits, then the best-fit non-linear equation which represents the data within these limits shall be used to determine concentration values. (c) The initial and periodic interference, system check...

Laboratory investigations of Titan haze formation: In situ measurement of gas and particle composition

NASA Astrophysics Data System (ADS)

Hörst, Sarah M.; Yoon, Y. Heidi; Ugelow, Melissa S.; Parker, Alex H.; Li, Rui; de Gouw, Joost A.; Tolbert, Margaret A.

2018-02-01

Prior to the arrival of the Cassini-Huygens spacecraft, aerosol production in Titan's atmosphere was believed to begin in the stratosphere where chemical processes are predominantly initiated by far ultraviolet (FUV) radiation. However, measurements taken by the Cassini Ultraviolet Imaging Spectrograph (UVIS) and Cassini Plasma Spectrometer (CAPS) indicate that haze formation initiates in the thermosphere where there is a greater flux of extreme ultraviolet (EUV) photons and energetic particles available to initiate chemical reactions, including the destruction of N2. The discovery of previously unpredicted nitrogen species in measurements of Titan's atmosphere by the Cassini Ion and Neutral Mass Spectrometer (INMS) indicates that nitrogen participates in the chemistry to a much greater extent than was appreciated before Cassini. The degree of nitrogen incorporation in the haze particles is important for understanding the diversity of molecules that may be present in Titan's atmosphere and on its surface. We have conducted a series of Titan atmosphere simulation experiments using either spark discharge (Tesla coil) or FUV photons (deuterium lamp) to initiate chemistry in CH4/N2 gas mixtures ranging from 0.01% CH4/99.99% N2 to 10% CH4/90% N2. We obtained in situ real-time measurements using a high-resolution time-of-flight aerosol mass spectrometer (HR-ToF-AMS) to measure the particle composition as a function of particle size and a proton-transfer ion-trap mass spectrometer (PIT-MS) to measure the composition of gas phase products. These two techniques allow us to investigate the effect of energy source and initial CH4 concentration on the degree of nitrogen incorporation in both the gas and solid phase products. The results presented here confirm that FUV photons produce not only solid phase nitrogen bearing products but also gas phase nitrogen species. We find that in both the gas and solid phase, nitrogen is found in nitriles rather than amines and that both the gas phase and solid phase products are composed primarily of molecules with a low degree of aromaticity. The UV experiments reproduce the absolute abundances measured in Titan's stratosphere for a number of gas phase species including C4H2, C6H6, HCN, CH3CN, HC3N, and C2H5CN.

Characteristics of two novel cold- and salt-tolerant ammonia-oxidizing bacteria from Liaohe Estuarine Wetland.

PubMed

Huang, Xiao; Bai, Jie; Li, Kui-Ran; Zhao, Yang-Guo; Tian, Wei-Jun; Dang, Jia-Jia

2017-01-15

To achieve a better contaminant removal efficiency in a low-temperature and high-salt environment, two novel strains of cold- and salt-tolerant ammonia-oxidizing bacteria (AOB), i.e., Ochrobactrum sp. (HXN-1) and Aquamicrobium sp. (HXN-2), were isolated from the surface sediment of Liaohe Estuarine Wetland (LEW), China. The optimization of initial ammonia nitrogen concentration, pH, carbon-nitrogen ratio, and petroleum hydrocarbons (PHCs) to improve the ammonia-oxidation capacity of the two bacterial strains was studied. Both bacterial strains showed a high ammonia nitrogen removal rate of over 80% under a high salinity of 10‰. Even at a temperature as low as 15°C, HXN-1 and HXN-2 could achieve an ammonia nitrogen removal rate of 53% and 62%, respectively. The cold- and salt-tolerant AOB in this study demonstrated a high potential for ammonia nitrogen removal from LEW. Copyright © 2016 Elsevier Ltd. All rights reserved.

Improved ADM1 model for anaerobic digestion process considering physico-chemical reactions.

PubMed

Zhang, Yang; Piccard, Sarah; Zhou, Wen

2015-11-01

The "Anaerobic Digestion Model No. 1" (ADM1) was modified in the study by improving the bio-chemical framework and integrating a more detailed physico-chemical framework. Inorganic carbon and nitrogen balance terms were introduced to resolve the discrepancies in the original bio-chemical framework between the carbon and nitrogen contents in the degraders and substrates. More inorganic components and solids precipitation processes were included in the physico-chemical framework of ADM1. The modified ADM1 was validated with the experimental data and used to investigate the effects of calcium ions, magnesium ions, inorganic phosphorus and inorganic nitrogen on anaerobic digestion in batch reactor. It was found that the entire anaerobic digestion process might exist an optimal initial concentration of inorganic nitrogen for methane gas production in the presence of calcium ions, magnesium ions and inorganic phosphorus. Copyright © 2015 Elsevier Ltd. All rights reserved.

Trends in nitrogen isotope ratios of juvenile winter flounder reflect changing nitrogen inputs to Rhode Island, USA estuarine systems.

PubMed

Pruell, Richard J; Taplin, Bryan K; Miller, Kenneth M

2017-05-15

Nitrogen isotope ratios (δ 15 N) in juvenile winter flounder, Pseudopleuronectes americanus, were used to examine changes in nitrogen inputs to several Rhode Island, USA estuarine systems. Fish were collected over two three-year periods with a ten-year interval between sampling periods (2002-2004 and 2012-2014). During that interval numerous changes to nutrient management practices were initiated in the watersheds of these estuarine systems including the upgrade of several major wastewater treatment facilities that discharge to Narragansett Bay, which significantly reduced nitrogen inputs. Following these reductions, the δ 15 N values of flounder in several of the systems decreased as expected; however, isotope ratios in fish from upper Narragansett Bay significantly increased. We believe that low δ 15 N values measured in 2002-2004 were related to concentration-dependent fractionation at this location. Increased δ 15 N values measured between 2012 and 2014 may indicate reduced fractionation or that changes in wastewater treatment processes altered the nitrogen isotopic ratios of the effluents. Published by Elsevier Ltd.

Nitrogen removal pathway of anaerobic ammonium oxidation in on-site aged refuse bioreactor.

PubMed

Wang, Chao; Zhao, Youcai; Xie, Bing; Peng, Qing; Hassan, Muhammad; Wang, Xiaoyuan

2014-05-01

The nitrogen removal pathways and nitrogen-related functional genes in on-site three-stage aged refuse bioreactor (ARB) treating landfill leachate were investigated. It was found that on average 90.0% of CODCr, 97.6% of BOD5, 99.3% of NH4(+)-N, and 81.0% of TN were removed with initial CODCr, BOD5, NH4(+)-N, and TN concentrations ranging from 2323 to 2754, 277 to 362, 1237 to 1506, and 1251 to 1580 mg/L, respectively. Meanwhile, the functional genes amoA, nirS and anammox 16S rRNA gene were found to coexist in every bioreactor, and their relative proportions in each bioreactor were closely related to the pollutant removal performance of the corresponding bioreactor, which indicated the coexistence of multiple nitrogen removal pathways in the ARB. Detection of anammox expression proved the presence of the anammox nitrogen removal pathway during the process of recirculating mature leachate to the on-site ARB, which provides important information for nitrogen management in landfills. Copyright © 2014 Elsevier Ltd. All rights reserved.

Long-term trends in nutrient budgets of the western Dutch Wadden Sea (1976-2012)

NASA Astrophysics Data System (ADS)

Jung, A. S.; Brinkman, A. G.; Folmer, E. O.; Herman, P. M. J.; van der Veer, H. W.; Philippart, C. J. M.

2017-09-01

Long-term field observations of nitrogen [N] and phosphorus [P] concentrations were used to construct nutrient budgets for the western Dutch Wadden Sea between 1976 and 2012. Nutrients come into the western Dutch Wadden Sea via river runoff, through exchange with the coastal zone of the North Sea, neighbouring tidal basins and through atmospheric deposition (for N). The highest concentrations in phosphorus and nitrogen were observed in the mid-1980s. Improved phosphorus removal at waste water treatment plants, management of fertilization in agriculture and removal of phosphates from detergents led to reduced riverine nutrient inputs and, consequently, reduced nutrient concentrations in the Wadden Sea. The budgets suggest that the period of the initial net import of phosphorus and nitrogen switched to a net export in 1981 for nitrogen and in 1992 for phosphorus. Such different behaviour in nutrient budgets during the rise and fall of external nutrient concentrations may be the result of different sediment-water exchange dynamics for P and N. It is hypothesized that during the period of increasing eutrophication (1976-1981) P, and to a lesser degree N, were stored in sediments as organic and inorganic nutrients. In the following period (1981-1992) external nutrient concentrations (especially in the North Sea) decreased, but P concentrations in the Wadden Sea remained high due to prolonged sediment release, whilst denitrification removed substantial amounts of N. From 1992 onwards, P and N budgets were closed by net loss, most probably because P stores were then depleted and denitrification continued. Under the present conditions (lower rates of sediment import and depleted P stores), nutrient concentrations in this area are expected to be more strongly influenced by wind-driven exchange with the North Sea and precipitation-driven discharge from Lake IJssel. This implies that the consequences of climate change will be more important, than during the 1970s and 1980s.

SENSITIVITY OF NITROGEN CONCENTRATIONS IN ESTUARIES TO LOADING AND WATER RESIDENCE TIME: APPLICATION TO THE POTOMAC ESTUARY

EPA Science Inventory

We use a simple nitrogen budget model to analyze concentrations of total nitrogen (TN) in estuaries for which both nitrogen inputs and water residence time are correlated with freshwater inflow rates. While the nitrogen concentration of an estuary varies linearly with TN loading ...

Electro-Fenton oxidation of reverse osmosis concentrate from sanitary landfill leachate: Evaluation of operational parameters.

PubMed

Fernandes, Annabel; Labiadh, Lazhar; Ciríaco, Lurdes; Pacheco, Maria José; Gadri, Abdellatif; Ammar, Salah; Lopes, Ana

2017-10-01

The electro-Fenton oxidation of a concentrate from reverse osmosis of a sanitary landfill leachate, with an initial chemical oxygen demand (COD) of 42 g L -1 , was carried out using a carbon-felt cathode and a boron doped diamond anode. The influence of the applied current intensity, initial pH and dissolved iron initial concentration on the electro-Fenton process was assessed. For the experimental conditions used, results showed that the initial pH is the parameter that more strongly influences the current efficiency of the electro-Fenton process, being this influence more pronounced on the oxidation rate than on the mineralization rate of the organic matter. The increase in iron initial concentration was found to be detrimental, since the natural amount of iron present in the effluent, 73 mg L -1 of total iron and 61 mg L -1 of dissolved iron, was sufficient to ensure the electro-Fenton process at the applied intensities - 0.2-1.4 A. For the more favourable conditions studied, initial pH of 3 and natural iron concentration, it was found an increase in the organic load and nitrogen removals with the applied current intensity. For the highest current intensity applied, a COD removal of 16.7 g L -1 was achieved after 8-h experiments. Copyright © 2017 Elsevier Ltd. All rights reserved.

THE EFFECTS OF INITIAL ABUNDANCES ON NITROGEN IN PROTOPLANETARY DISKS

DOE Office of Scientific and Technical Information (OSTI.GOV)

Schwarz, Kamber R.; Bergin, Edwin A.

2014-12-20

The dominant form of nitrogen provided to most solar system bodies is currently unknown, though available measurements show that the detected nitrogen in solar system rocks and ices is depleted with respect to solar abundances and the interstellar medium. We use a detailed chemical/physical model of the chemical evolution of a protoplanetary disk to explore the evolution and abundance of nitrogen-bearing molecules. Based on this model, we analyze how initial chemical abundances provided as either gas or ice during the early stages of disk formation influence which species become the dominant nitrogen bearers at later stages. We find that amore » disk with the majority of its initial nitrogen in either atomic or molecular nitrogen is later dominated by atomic and molecular nitrogen as well as NH{sub 3} and HCN ices, where the dominant species varies with disk radius. When nitrogen is initially in gaseous ammonia, it later becomes trapped in ammonia ice except in the outer disk where atomic nitrogen dominates. For a disk with the initial nitrogen in the form of ammonia ice, the nitrogen remains trapped in the ice as NH{sub 3} at later stages. The model in which most of the initial nitrogen is placed in atomic N best matches the ammonia abundances observed in comets. Furthermore, the initial state of nitrogen influences the abundance of N{sub 2}H{sup +}, which has been detected in protoplanetary disks. Strong N{sub 2}H{sup +} emission is found to be indicative of an N{sub 2} abundance greater than n{sub N{sub 2}}/n{sub H{sub 2}}>10{sup −6} in addition to tracing the CO snow line. Our models also indicate that NO is potentially detectable, with lower N gas abundances leading to higher NO abundances.« less

Application of titration methods for measuring the contents of ammonium nitrogen and volatile fatty acids in agricultural biogas plants.

PubMed

Piątek, Michał; Lisowski, Aleksander; Lisowska, Barbara

2017-12-20

The aim of our research was to assess a relatively new method of estimating ammonium nitrogen concentration in anaerobic digestion of plant substrates. We analysed our own data, received from the anaerobic digestion of maize silage (PM), as well as data published by Purser et al. (2014) who measured energy crops and slurry (ECS), and food waste (FW). In our study, the process was monitored for VFA content that was determined by gas chromatography, and for the content of ammonium nitrogen determined using the HACH LANGE LCK 303 cuvette test. We created polynomial regression models that bind the content of ammonium nitrogen with the volume of H 2 SO 4 used to titrate the sample from initial pH to pH 5. To estimate parameters of model, the PM dataset was used. The obtained models were positively validated using ECS and FW datasets. Our results confirmed the effectiveness of the Purser et al. method with an average absolute error of less than 223mgl -1 of the VFA concentration, which was approximately 20-times less than the level that caused inhibition. In conclusion, we can affirm the suitability of using titration methods to assess the ammonium nitrogen content of bioreactors with a stable composition. Copyright © 2017 Elsevier B.V. All rights reserved.

Regulation of nitrogen uptake and assimilation: Effects of nitrogen source and root-zone and aerial environment on growth and productivity of soybean

NASA Technical Reports Server (NTRS)

Raper, C. David, Jr.

1994-01-01

The interdependence of root and shoot growth produces a functional equilibrium as described in quantitative terms by numerous authors. It was noted that bean seedlings grown in a constant environment tended to have a constant distribution pattern of dry matter between roots and leaves characteristic of the set of environmental conditions. Disturbing equilibrium resulted in a change in relative growth of roots and leaves until the original ratio was restored. To define a physiological basis for regulation of nitrogen uptake within the balance between root and shoot activities, the authors combined a partioning scheme and a utilization priority assumption in which: (1) all carbon enters the plant through photosynthesis in leaves and all nitrogen enters the plant through active uptake by roots, (2) nitrogen uptake by roots and secretion into the xylem for transport to the shoots are active processes, (3) availability of exogenous nitrogen determines concentration of soluble carbohydrates within the roots, (4) leaves are a source and a sink for carbohydrates, and (5) the requirement for nitrogen by leaf growth is proportionally greater during initiation and early expansion than during later expansion.

Nitrogen, phosphorus, organic carbon, and biochemical oxygen demand : in Florida surface waters, 1972

USGS Publications Warehouse

Kaufman, Matthew I.; Dysart, J.E.

1978-01-01

Water samples were collected during spring and autumn 1972 from about 100 surface-water sites in Florida. The samples were analyzed for the plant nutrients, nitrogen and phosphorus. In most waters, nitrogen concentrations are less than 2.0 milligrams per liter as nitrogen, and organic nitrogen is dominant. Median total nitrogen concentration for Florida surface waters is between 1.2 and 2.0 milligrams per liter as nitrogen. In samples from 85 percent of the sites, total nitrogen exceeded 0.6 milligrams per liter. Median total phosphorus concentration as phosphorus for Florida surface waters is between 0.05 and 0.1 milligrams per liter. The information will form a base useful to agencies concerned with setting concentration limits for nitrogen and phosphorus in industrial and sewage plant outfalls. (Woodard-USGS)

Long-term purification efficiency of a wetland constructed to treat runoff from peat extraction.

PubMed

Karjalainen, Satu M; Heikkinen, Kaisa; Ihme, Raimo; Kløve, Bjørn

2016-01-01

Peat extraction increases the phosphorus, nitrogen, organic matter, suspended solids, and iron concentrations in runoff, resulting in negative effects on downstream water bodies. Wetlands are commonly used as natural cost-effective solutions to mitigate these negative effects. This study analyzed changes in the quality of runoff water from peat extraction areas and the long-term efficiency of constructed wetlands. The results indicate that the quality of runoff water changed after the initial drainage and during peat extraction. Nitrogen leached at high concentrations in the early stages of peat extraction following drainage, whereas the leaching of iron and phosphorus increased after peat extraction from deeper layers. Comparison of water quality and impurities retained immediately after treatment wetland construction and 14 years later showed that the treatment wetland remained functional, with good retention capacity, over a long period.

Microbial lipid production by Rhodosporidium toruloides under sulfate-limited conditions.

PubMed

Wu, Siguo; Zhao, Xin; Shen, Hongwei; Wang, Qian; Zhao, Zongbao K

2011-01-01

Novel biochemical approaches remain to be developed to improve microbial lipid technology. This study demonstrated that sulfate limitation was effective to promote accumulating substantial amounts of intracellular lipid by the oleaginous yeast Rhodosporidium toruloides Y4. When it was cultivated using a medium with an initial carbon-to-sulfur (C/S) molar ratio of 46,750, cellular lipid content reached up to 58.3%. The time courses of cell growth, lipid accumulation and nutrient depletion were analyzed and discussed in terms of lipid biosynthesis. Moreover, lipid accumulation under sulfate-limited conditions was effective regardless of the presence of a high concentration of nitrogen sources. Thus, lipid contents almost held constant at near 57% in the media with an initial C/S molar ratio of 11,380 although the carbon-to-nitrogen molar ratio ranged from 28.3 to 5.7. Taken together, our results established the sulfate-limitation approach to control lipid biosynthesis, which should be valuable to explore nitrogen-rich raw materials as the feedstock for lipid production. Copyright © 2010 Elsevier Ltd. All rights reserved.

Advanced low carbon-to-nitrogen ratio wastewater treatment by electrochemical and biological coupling process.

PubMed

Deng, Shihai; Li, Desheng; Yang, Xue; Zhu, Shanbin; Xing, Wei

2016-03-01

Nitrogen pollution in ground and surface water significantly affects the environment and its organisms, thereby leading to an increasingly serious environmental problem. Such pollution is difficult to degrade because of the lack of carbon sources. Therefore, an electrochemical and biological coupling process (EBCP) was developed with a composite catalytic biological carrier (CCBC) and applied in a pilot-scale cylindrical reactor to treat wastewater with a carbon-to-nitrogen (C/N) ratio of 2. The startup process, coupling principle, and dynamic feature of the EBCP were examined along with the effects of hydraulic retention time (HRT), dissolved oxygen (DO), and initial pH on nitrogen removal. A stable coupling system was obtained after 51 days when plenty of biofilms were cultivated on the CCBC without inoculation sludge. Autotrophic denitrification, with [Fe(2+)] and [H] produced by iron-carbon galvanic cells in CCBC as electron donors, was confirmed by equity calculation of CODCr and nitrogen removal. Nitrogen removal efficiency was significantly influenced by HRT, DO, and initial pH with optimal values of 3.5 h, 3.5 ± 0.1 mg L(-1), and 7.5 ± 0.1, respectively. The ammonia, nitrate, and total nitrogen (TN) removal efficiencies of 90.1 to 95.3 %, 90.5 to 99.0 %, and 90.3 to 96.5 % were maintained with corresponding initial concentrations of 40 ± 2 mg L(-1) (NH3-N load of 0.27 ± 0.01 kg NH3-N m(-3) d(-1)), 20 ± 1 mg L(-1), and 60 ± 2 mg L(-1) (TN load of 0.41 ± 0.02 kg TN m(-3) d(-1)). Based on the Eckenfelder model, the kinetics equation of the nitrogen transformation along the reactor was N e  = N 0 exp (-0.04368 h/L(1.8438)). Hence, EBCP is a viable method for advanced low C/N ratio wastewater treatment.

Simplified Two-Time Step Method for Calculating Combustion Rates and Nitrogen Oxide Emissions for Hydrogen/Air and Hydorgen/Oxygen

NASA Technical Reports Server (NTRS)

Molnar, Melissa; Marek, C. John

2005-01-01

A simplified single rate expression for hydrogen combustion and nitrogen oxide production was developed. Detailed kinetics are predicted for the chemical kinetic times using the complete chemical mechanism over the entire operating space. These times are then correlated to the reactor conditions using an exponential fit. Simple first order reaction expressions are then used to find the conversion in the reactor. The method uses a two-time step kinetic scheme. The first time averaged step is used at the initial times with smaller water concentrations. This gives the average chemical kinetic time as a function of initial overall fuel air ratio, temperature, and pressure. The second instantaneous step is used at higher water concentrations (> 1 x 10(exp -20) moles/cc) in the mixture which gives the chemical kinetic time as a function of the instantaneous fuel and water mole concentrations, pressure and temperature (T4). The simple correlations are then compared to the turbulent mixing times to determine the limiting properties of the reaction. The NASA Glenn GLSENS kinetics code calculates the reaction rates and rate constants for each species in a kinetic scheme for finite kinetic rates. These reaction rates are used to calculate the necessary chemical kinetic times. This time is regressed over the complete initial conditions using the Excel regression routine. Chemical kinetic time equations for H2 and NOx are obtained for H2/air fuel and for the H2/O2. A similar correlation is also developed using data from NASA s Chemical Equilibrium Applications (CEA) code to determine the equilibrium temperature (T4) as a function of overall fuel/air ratio, pressure and initial temperature (T3). High values of the regression coefficient R2 are obtained.

Summary of Simplified Two Time Step Method for Calculating Combustion Rates and Nitrogen Oxide Emissions for Hydrogen/Air and Hydrogen/Oxygen

NASA Technical Reports Server (NTRS)

Marek, C. John; Molnar, Melissa

2005-01-01

A simplified single rate expression for hydrogen combustion and nitrogen oxide production was developed. Detailed kinetics are predicted for the chemical kinetic times using the complete chemical mechanism over the entire operating space. These times are then correlated to the reactor conditions using an exponential fit. Simple first order reaction expressions are then used to find the conversion in the reactor. The method uses a two time step kinetic scheme. The first time averaged step is used at the initial times with smaller water concentrations. This gives the average chemical kinetic time as a function of initial overall fuel air ratio, temperature, and pressure. The second instantaneous step is used at higher water concentrations (greater than l x 10(exp -20)) moles per cc) in the mixture which gives the chemical kinetic time as a function of the instantaneous fuel and water mole concentrations, pressure and temperature (T(sub 4)). The simple correlations are then compared to the turbulent mixing times to determine the limiting properties of the reaction. The NASA Glenn GLSENS kinetics code calculates the reaction rates and rate constants for each species in a kinetic scheme for finite kinetic rates. These reaction rates are used to calculate the necessary chemical kinetic times. This time is regressed over the complete initial conditions using the Excel regression routine. Chemical kinetic time equations for H2 and NOx are obtained for H2/Air fuel and for H2/O2. A similar correlation is also developed using data from NASA's Chemical Equilibrium Applications (CEA) code to determine the equilibrium temperature (T(sub 4)) as a function of overall fuel/air ratio, pressure and initial temperature (T(sub 3)). High values of the regression coefficient R squared are obtained.

The role of nitrogen and phosphorus in regulating Phormidium sp. (cyanobacteria) growth and anatoxin production.

PubMed

Heath, Mark; Wood, Susie A; Young, Roger G; Ryan, Ken G

2016-03-01

Benthic proliferations of the cyanobacteria Phormidium can cover many kilometres of riverbed. Phormidium can produce neurotoxic anatoxins and ingestion of benthic mats has resulted in numerous animal poisonings in the last decade. Despite this, there is a poor understanding of the environmental factors regulating growth and anatoxin production. In this study, the effects of nitrogen and phosphorus on the growth of two Phormidium strains (anatoxin-producing and non-anatoxin-producing) were examined in batch monocultures. Cell concentrations were significantly reduced under reduced nitrogen (ca. <0.100 mM) and phosphorus conditions (ca. <0.003 mM). Cell concentrations and maximum growth rates were higher for the non-anatoxin-producing strain in all treatments, suggesting there may be an energetic cost to toxin production. Cellular anatoxin concentrations were lowest (169 fg cell(-1)) under the high-nitrogen and high-phosphorus treatment. This supports the growth-differentiation balance hypothesis that suggests actively dividing and expanding cells are less likely to produce secondary-metabolites. Anatoxin quota was highest (>407 fg cell(-1)) in the reduced phosphorus treatments, possibly suggesting that it is produced as a stress response to growth limiting conditions. In all treatments there was a 4-5-fold increase in anatoxin quota in the lag growth phase, possibly indicating it may provide a physiological benefit during initial substrate colonization. © FEMS 2016. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

Saccharomyces and non-Saccharomyces Competition during Microvinification under Different Sugar and Nitrogen Conditions

PubMed Central

Lleixà, Jessica; Manzano, Maria; Mas, Albert; Portillo, María del C.

2016-01-01

The inoculation of wines with autochthonous yeast allows obtaining complex wines with a peculiar microbial footprint characteristic from a wine region. Mixed inoculation of non-Saccharomyces yeasts and S. cerevisiae is of interest for the wine industry for technological and sensory reasons. However, the interactions between these yeasts are not well understood, especially those regarding the availability of nutrients. The aim of the present study was to analyze the effect of nitrogen and sugar concentration on the evolution of mixed yeast populations on controlled laboratory-scale fermentations monitored by density, plate culturing, PCR-DGGE and sugar and nitrogen consumption. Furthermore, the effect of the time of inoculation of Saccharomyces cerevisiae respect the initial co-inoculation of three non-Saccharomyces yeasts was evaluated over the evolution of fermentation. Our results have shown that S. cerevisiae inoculation during the first 48 h conferred a stabilizing effect over the fermentations with non-Saccharomyces strains tested and, generally, reduced yeast diversity at the end of the fermentation. On the other hand, nitrogen limitation increased the time of fermentation and also the proportion of non-Saccharomyces yeasts at mid and final fermentation. High sugar concentration resulted in different proportions of the inoculated yeast depending on the time of S. cerevisiae inoculation. This work emphasizes the importance of the concentration of nutrients on the evolution of mixed fermentations and points to the optimal conditions for a stable fermentation in which the inoculated yeasts survived until the end. PMID:27994585

[Progress in inversion of vegetation nitrogen concentration by hyperspectral remote sensing].

PubMed

Wang, Li-Wen; Wei, Ya-Xing

2013-10-01

Nitrogen is the necessary element in life activity of vegetation, which takes important function in biosynthesis of protein, nucleic acid, chlorophyll, and enzyme etc, and plays a key role in vegetation photosynthesis. The technology about inversion of vegetation nitrogen concentration by hyperspectral remote sensing has been the research hotspot since the 70s of last century. With the development of hyperspectral remote sensing technology in recent years, the advantage of spectral bands subdivision in a certain spectral region provides the powerful technology measure for correlative spectral characteristic research on vegetation nitrogen. In the present paper, combined with the newest research production about monitoring vegetation nitrogen concentration by hyperspectral remote sensing published in main geography science literature in recent several years, the principle and correlated problem about monitoring vegetation nitrogen concentration by hyperspectral remote sensing were introduced. From four aspects including vegetation nitrogen spectral index, vegetation nitrogen content inversion based on chlorophyll index, regression model, and eliminating influence factors to inversion of vegetation nitrogen concentration, main technology methods about inversion of vegetation nitrogen concentration by hyperspectral remote sensing were detailedly introduced. Correlative research conclusions were summarized and analyzed, and research development trend was discussed.

Impact of assimilable nitrogen availability in glucose uptake kinetics in Saccharomyces cerevisiae during alcoholic fermentation

PubMed Central

2012-01-01

Background The expression and activity of the different Saccharomyces cerevisiae hexose uptake systems (Hxt) and the kinetics of glucose uptake are considered essential to industrial alcoholic fermentation performance. However, the dynamics of glucose uptake kinetics during the different stages of fermentation, depending on glucose and nitrogen availability, is very poorly characterized. The objective of the present work was to examine thoroughly the alterations occurring in glucose uptake kinetics during alcoholic fermentation, by the wine strain S. cerevisiae PYCC 4072, of a synthetic grape juice basal medium with either a limiting or non-limiting initial nitrogen concentration and following nitrogen supplementation of the nitrogen-depleted sluggish fermentation. Results Independently of the initial concentration of the nitrogen source, glucose transport capacity is maximal during the early stages of fermentation and presumably sustained by the low-affinity and high-capacity glucose transporter Hxt1p. During nitrogen-limited sluggish fermentation, glucose uptake capacity was reduced to approximately 20% of its initial values (Vmax = 4.9 ± 0.8 compared to 21.9 ± 1.2 μmol h-1 10-8 cells), being presumably sustained by the low-affinity glucose transporter Hxt3p (considering the calculated Km = 39.2 ± 8.6 mM). The supplementation of the sluggish fermentation broth with ammonium led to the increase of glucose transport capacity associated to the expression of different glucose uptake systems with low and high affinities for glucose (Km = 58.2 ± 9.1 and 2.7 ± 0.4 mM). A biclustering analysis carried out using microarray data, previously obtained for this yeast strain transcriptional response to equivalent fermentation conditions, indicates that the activation of the expression of genes encoding the glucose transporters Hxt2p (during the transition period to active fermentation) and Hxt3p, Hxt4p, Hxt6p and Hxt7p (during the period of active fermentation) may have a major role in the recovery of glucose uptake rate following ammonium supplementation. These results suggest a general derepression of the glucose-repressible HXT genes and are consistent with the downregulation of Mig1p and Rgt1p. Conclusions Although reduced, glucose uptake rate during nitrogen-limited fermentation is not abrogated. Following ammonium supplementation, sluggish fermentation recovery is associated to the increase of glucose uptake capacity, related to the de novo synthesis of glucose transporters with different affinity for glucose and capacity, presumably of Hxt2p, Hxt3p, Hxt4p, Hxt6p and Hxt7p. This study is a contribution to the understanding of yeast response to different stages of alcoholic fermentation at the level of glucose uptake kinetics, in particular under nitrogen limitation or replenish, which is useful knowledge to guide fermentation practices. PMID:22846176

Metabolic and respiratory status of cold-stunned Kemp's ridley sea turtles (Lepidochelys kempii).

PubMed

Innis, Charles J; Tlusty, Michael; Merigo, Constance; Weber, E Scott

2007-08-01

"Cold-stunning" of sea turtles has been reported as a naturally occurring stressor for many years; however, the physiologic status of cold-stunned turtles has only been partially described. This study investigated initial and convalescent venous blood gas, acid-base, and critical plasma biochemical data for 26 naturally cold-stunned Kemp's ridley sea turtles (Lepidochelys kempii) from Cape Cod, MA, USA. Samples were analyzed for pH, pCO(2), pO(2), bicarbonate, plasma osmolality, sodium, potassium, chloride, ionized calcium, ionized magnesium, glucose, lactate, and blood urea nitrogen using a clinical point-of-care analyzer. Data were corrected for the patient's body temperature using both species-specific and more general correction methods. In general, venous blood gas, acid-base, and plasma biochemical data obtained for surviving cold-stunned Kemp's ridley sea turtles were consistent with previously documented data for sea turtles exposed to a wide range of temperatures and physiologic stressors. Data indicated that turtles were initially affected by metabolic and respiratory acidosis. Initial pH-corrected ionized calcium concentrations were lower than convalescent concentrations, and initial pH-corrected ionized magnesium concentrations were higher than convalescent concentrations.

Effects of temperature, algae biomass and ambient nutrient on the absorption of dissolved nitrogen and phosphate by Rhodophyte Gracilaria asiatica

NASA Astrophysics Data System (ADS)

Du, Rongbin; Liu, Liming; Wang, Aimin; Wang, Yongqiang

2013-03-01

Gracilaria asiatica, being highly efficient in nutrient absorption, is cultivated in sea cucumber ponds to remove nutrients such as nitrogen and phosphate. It was cultured in a laboratory simulating field conditions, and its nutrient absorption was measured to evaluate effects of environmental conditions. Ammonia nitrogen (AN), nitrate nitrogen (NN), total inorganic nitrogen (TIN), and soluble reactive phosphorus (SRP) uptake rate and removal efficiency were determined in a 4×2 factorial design experiment in water temperatures ( T) at 15°C and 25°C, algae biomass (AB) at 0.5 g/L and 1.0 g/L, total inorganic nitrogen (TIN) at 30 μmol/L and 60 μmol/L, and soluble reactive phosphorus (SRP) at 3 and 6 μmol/L. AB and ambient TIN or SRP levels significantly affected uptake rate and removal efficiency of AN, NN, TIN, and SRP ( P< 0.001). G. asiatica in AB of 0.5 g/L showed higher uptake rate and lower removal efficiency relative to that with AB of 1.0 g/L. Nitrogen and phosphorus uptake rate rose with increasing ambient nutrient concentrations; nutrient removal efficiency decreased at higher environmental nutrient concentrations. The algae preferred to absorb AN to NN. Uptake rates of AN, NN, and SRP were significantly affected by temperature ( P < 0.001); uptake rate was higher for the 25°C group than for the 15°C group at the initial experiment stage. Only the removal efficiency of AN and SRP showed a significant difference between the two temperature groups ( P< 0.01). The four factors had significant interactive effects on absorption of N and P, implying that G. asiatica has great bioremedial potential in sea cucumber culture ponds.

Equilibrium responses of global net primary production and carbon storage to doubled atmospheric carbon dioxide: Sensitivity to changes in vegetation nitrogen concentration

USGS Publications Warehouse

McGuire, David A.; Melillo, J.M.; Kicklighter, D.W.; Pan, Y.; Xiao, X.; Helfrich, J.; Moore, B.; Vorosmarty, C.J.; Schloss, A.L.

1997-01-01

We ran the terrestrial ecosystem model (TEM) for the globe at 0.5?? resolution for atmospheric CO2 concentrations of 340 and 680 parts per million by volume (ppmv) to evaluate global and regional responses of net primary production (NPP) and carbon storage to elevated CO2 for their sensitivity to changes in vegetation nitrogen concentration. At 340 ppmv, TEM estimated global NPP of 49.0 1015 g (Pg) C yr-1 and global total carbon storage of 1701.8 Pg C; the estimate of total carbon storage does not include the carbon content of inert soil organic matter. For the reference simulation in which doubled atmospheric CO2 was accompanied with no change in vegetation nitrogen concentration, global NPP increased 4.1 Pg C yr-1 (8.3%), and global total carbon storage increased 114.2 Pg C. To examine sensitivity in the global responses of NPP and carbon storage to decreases in the nitrogen concentration of vegetation, we compared doubled CO2 responses of the reference TEM to simulations in which the vegetation nitrogen concentration was reduced without influencing decomposition dynamics ("lower N" simulations) and to simulations in which reductions in vegetation nitrogen concentration influence decomposition dynamics ("lower N+D" simulations). We conducted three lower N simulations and three lower N+D simulations in which we reduced the nitrogen concentration of vegetation by 7,5, 15.0, and 22.5%. In the lower N simulations, the response of global NPP to doubled atmospheric CO2 increased approximately 2 Pg C yr-1 for each incremental 7.5% reduction in vegetation nitrogen concentration, and vegetation carbon increased approximately an additional 40 Pg C, and soil carbon increased an additional 30 Pg C, for a total carbon storage increase of approximately 70 Pg C. In the lower N+D simulations, the responses of NPP and vegetation carbon storage were relatively insensitive to differences in the reduction of nitrogen concentration, but soil carbon storage showed a large change. The insensitivity of NPP in the N+D simulations occurred because potential enhancements in NPP associated with reduced vegetation nitrogen concentration were approximately offset by lower nitrogen availability associated with the decomposition dynamics of reduced litter nitrogen concentration. For each 7.5% reduction in vegetation nitrogen concentration, soil carbon increased approximately an additional 60 Pg C, while vegetation carbon storage increased by only approximately 5 Pg C. As the reduction in vegetation nitrogen concentration gets greater in the lower N+D simulations, more of the additional carbon storage tends to become concentrated in the north temperateboreal region in comparison to the tropics. Other studies with TEM show that elevated CO2 more than offsets the effects of climate change to cause increased carbon storage. The results of this study indicate that carbon storage would be enhanced by the influence of changes in plant nitrogen concentration on carbon assimilation and decomposition rates. Thus changes in vegetation nitrogen concentration may have important implications for the ability of the terrestrial biosphere to mitigate increases in the atmospheric concentration of CO2 and climate changes associated with the increases.

A statistical experiment design approach for optimizing biodegradation of weathered crude oil in coastal sediments.

PubMed

Mohajeri, Leila; Aziz, Hamidi Abdul; Isa, Mohamed Hasnain; Zahed, Mohammad Ali

2010-02-01

This work studied the bioremediation of weathered crude oil (WCO) in coastal sediment samples using central composite face centered design (CCFD) under response surface methodology (RSM). Initial oil concentration, biomass, nitrogen and phosphorus concentrations were used as independent variables (factors) and oil removal as dependent variable (response) in a 60 days trial. A statistically significant model for WCO removal was obtained. The coefficient of determination (R(2)=0.9732) and probability value (P<0.0001) demonstrated significance for the regression model. Numerical optimization based on desirability function were carried out for initial oil concentration of 2, 16 and 30 g per kg sediment and 83.13, 78.06 and 69.92 per cent removal were observed respectively, compare to 77.13, 74.17 and 69.87 per cent removal for un-optimized results.

Percentile Distributions of Median Nitrite Plus Nitrate as Nitrogen, Total Nitrogen, and Total Phosphorus Concentrations in Oklahoma Streams, 1973-2001

USGS Publications Warehouse

Haggard, Brian E.; Masoner, Jason R.; Becker, Carol J.

2003-01-01

Nutrients are one of the primary causes of water-quality impairments in streams, lakes, reservoirs, and estuaries in the United States. The U.S. Environmental Protection Agency has developed regional-based nutrient criteria using ecoregions to protect streams in the United States from impairment. However, nutrient criteria were based on nutrient concentrations measured in large aggregated nutrient ecoregions with little relevance to local environmental conditions in states. The Oklahoma Water Resources Board is using a dichotomous process known as Use Support Assessment Protocols to define nutrient criteria in Oklahoma streams. The Oklahoma Water Resources Board is modifying the Use Support Assessment Protocols to reflect nutrient informa-tion and environmental characteristics relevant to Oklahoma streams, while considering nutrient information grouped by geographic regions based on level III ecoregions and state boundaries. Percentile distributions of median nitrite plus nitrate as nitrogen, total nitrogen, and total phosphorous concentrations were calculated from 563 sites in Oklahoma and 4 sites in Arkansas near the Oklahoma and Arkansas border to facilitate development of nutrient criteria for Oklahoma streams. Sites were grouped into four geographic regions and were categorized into eight stream categories by stream slope and stream order. The 50th percentiles of median nitrite plus nitrate as nitrogen, total nitrogen, and total phosphorus concentrations were greater in the Ozark Highland ecoregion and were less in the Ouachita Mountains ecoregion when compared to other geographic areas used to group sites. The 50th percentiles of median concentrations of nitrite plus nitrate as nitrogen, total nitrogen, and total phosphorus were least in first, second, and third order streams. The 50th percentiles of median nitrite plus nitrate as nitrogen, total nitrogen and total phosphorus concentrations in the Ozark Highland and Ouachita Mountains ecoregions were least in first, second, and third order streams with streams slopes greater than 17 feet per mile. Nitrite plus nitrate as nitrogen and total nitrogen criteria determined by the U.S. Environmental Protection Agency for the Ozark Highland ecoregion were less than the 25th percentiles of median nitrite plus nitrate as nitrogen, total nitrogen, and total phosphorus concentrations in the Ozark Highland ecoregion calculated for this report. Nitrite plus nitrate as nitrogen and total nitrogen criteria developed by the U.S. Environmental Protection Agency for the Ouachita Mountains ecoregion were similar to the 25th percentiles of median nitrite plus nitrate as nitrogen and total nitrogen concentrations in the Ouachita Mountains ecoregion calculated for this report. Nitrate as nitrogen and total phosphorus concentrations currently (2002) used in the Use Support Assessment Protocols for Oklahoma were greater than the 75th percentiles of median nitrite plus nitrate as nitrogen and total phosphorus concentrations calculated for this report.

Fate of Nutrients in Shallow Groundwater Receiving Treated Septage, Malibu, CA

PubMed Central

Izbicki, John A

2014-01-01

Treated wastewater discharged from more than 400 onsite wastewater treatment systems (OWTS) near the Civic Center area of Malibu, California, 40 km west of downtown Los Angeles, composes 28% of the recharge to a 3.4 km2 alluvial aquifer. On the basis of δ18O and δD data, the fraction of wastewater in some samples was >70%. Ammonium and nitrate concentrations in water from 15 water-table wells sampled in July 2009 and April 2010 ranged from <0.01 to 12 milligrams per liter as nitrogen (mg/L as N), and from <0.01 to 11 mg/L as N, respectively. Chemical and isotopic data (δ15N of ammonium and nitrate, and δ18O of nitrate) show two processes remove nitrogen discharged from OWTS. Where groundwater was reducing, sorption of ammonium resulted in 30 to 50% nitrogen removal. Where groundwater was initially oxic, nitrification with subsequent denitrification as reducing conditions developed, resulted in up to 60% nitrogen removal. Nitrogen removal through sorption dominated during the cooler April sample period, and denitrification dominated during the warmer July sample period. The combination of mixing and nitrogen removal due to denitrification, sorption, and volatilization produces a δ15N apparent fractionation factor (εapp = −5), that can be explained using laboratory-derived fractionation factors (ε) for the individual processes. Phosphate concentrations ranged from < 0.04 to 2 mg/L as phosphorous. Sorption to iron oxides on the surfaces of mineral grains at near-neutral pH's removed some phosphate; however, little removal occurred at more alkaline pH's (>7.3). PMID:24902718

Fate of nutrients in shallow groundwater receiving treated septage, Malibu, CA

USGS Publications Warehouse

Izbicki, John

2014-01-01

Treated wastewater discharged from more than 400 onsite wastewater treatment systems (OWTS) near the Civic Center area of Malibu, California, 40 km west of downtown Los Angeles, composes 28% of the recharge to a 3.4 km2 alluvial aquifer. On the basis of δ18O and δD data, the fraction of wastewater in some samples was >70%. Ammonium and nitrate concentrations in water from 15 water-table wells sampled in July 2009 and April 2010 ranged from <0.01 to 12 milligrams per liter as nitrogen (mg/L as N), and from <0.01 to 11 mg/L as N, respectively. Chemical and isotopic data (δ15N of ammonium and nitrate, and δ18O of nitrate) show two processes remove nitrogen discharged from OWTS. Where groundwater was reducing, sorption of ammonium resulted in 30 to 50% nitrogen removal. Where groundwater was initially oxic, nitrification with subsequent denitrification as reducing conditions developed, resulted in up to 60% nitrogen removal. Nitrogen removal through sorption dominated during the cooler April sample period, and denitrification dominated during the warmer July sample period. The combination of mixing and nitrogen removal due to denitrification, sorption, and volatilization produces a δ15N apparent fractionation factor (εapp= -5), that can be explained using laboratory-derived fractionation factors (ε) for the individual processes. Phosphate concentrations ranged from <0.04 to 2 mg/L as phosphorous. Sorption to iron oxides on the surfaces of mineral grains at near-neutral pH's removed some phosphate; however, little removal occurred at more alkaline pH's (>7.3).

Numerical model simulations of nitrate concentrations in groundwater using various nitrogen input scenarios, mid-Snake region, south-central Idaho

USGS Publications Warehouse

Skinner, Kenneth D.; Rupert, Michael G.

2012-01-01

As part of the U.S. Geological Survey’s National Water Quality Assessment (NAWQA) program nitrate transport in groundwater was modeled in the mid-Snake River region in south-central Idaho to project future concentrations of nitrate. Model simulation results indicated that nitrate concentrations would continue to increase over time, eventually exceeding the U.S. Environmental Protection Agency maximum contaminant level for drinking water of 10 milligrams per liter in some areas. A subregional groundwater model simulated the change of nitrate concentrations in groundwater over time in response to three nitrogen input scenarios: (1) nitrogen input fixed at 2008 levels; (2) nitrogen input increased from 2008 to 2028 using the same rate of increase as the average rate of increase during the previous 10 years (1998 through 2008); after 2028, nitrogen input is fixed at 2028 levels; and (3) nitrogen input related to agriculture completely halted, with only nitrogen input from precipitation remaining. Scenarios 1 and 2 project that nitrate concentrations in groundwater continue to increase from 10 to 50 years beyond the year nitrogen input is fixed, depending on the location in the model area. Projected nitrate concentrations in groundwater increase by as much as 2–4 milligrams per liter in many areas, with nitrate concentrations in some areas reaching 10 milligrams per liter. Scenario 3, although unrealistic, estimates how long (20–50 years) it would take nitrate in groundwater to return to background concentrations—the “flushing time” of the system. The amount of nitrate concentration increase cannot be explained solely by differences in nitrogen input; in fact, some areas with the highest amount of nitrogen input have the lowest increase in nitrate concentration. The geometry of the aquifer and the pattern of regional groundwater flow through the aquifer greatly influence nitrate concentrations. The aquifer thins toward discharge areas along the Snake River which forces upward convergence of good-quality regional groundwater that mixes with the nitrate-laden groundwater in the uppermost parts of the aquifer, which results in lowered nitrate concentrations. A new method of inputting nitrogen to the subregional groundwater model was used that prorates nitrogen input by the probability of detecting nitrate concentrations greater than 2 mg/L. The probability map is based on correlations with physical factors, and prorates an existing nitrogen input dataset providing an estimate of nitrogen flux to the water table that accounts for new factors such as soil properties. The effectiveness of this updated nitrogen input method was evaluated using the software UCODE_2005.

Nitrogen Limited Red and Green Leaf Lettuce Accumulate Flavonoid Glycosides, Caffeic Acid Derivatives, and Sucrose while Losing Chlorophylls, Β-Carotene and Xanthophylls.

PubMed

Becker, Christine; Urlić, Branimir; Jukić Špika, Maja; Kläring, Hans-Peter; Krumbein, Angelika; Baldermann, Susanne; Goreta Ban, Smiljana; Perica, Slavko; Schwarz, Dietmar

2015-01-01

Reduction of nitrogen application in crop production is desirable for ecological and health-related reasons. Interestingly, nitrogen deficiency can lead to enhanced concentrations of polyphenols in plants. The reason for this is still under discussion. The plants' response to low nitrogen concentration can interact with other factors, for example radiation intensity. We cultivated red and green leaf lettuce hydroponically in a Mediterranean greenhouse, supplying three different levels of nitrogen (12 mM, 3 mM, 0.75 mM), either in full or reduced (-50%) radiation intensity. In both red and green lettuce, we found clear effects of the nitrogen treatments on growth characteristics, phenolic and photosynthetic compounds, nitrogen, nitrate and carbon concentration of the plants. Interestingly, the concentrations of all main flavonoid glycosides, caffeic acid derivatives, and sucrose increased with decreasing nitrogen concentration, whereas those of chlorophylls, β-carotene, neoxanthin, lactucaxanthin, all trans- and cis-violaxanthin decreased. The constitutive concentrations of polyphenols were lower in the green cultivar, but their relative increase was more pronounced than in the red cultivar. The constitutive concentrations of chlorophylls, β-carotene, neoxanthin, all trans- and cis-violaxanthin were similar in red and green lettuce and with decreasing nitrogen concentration they declined to a similar extent in both cultivars. We only detected little influence of the radiation treatments, e.g. on anthocyanin concentration, and hardly any interaction between radiation and nitrogen concentration. Our results imply a greater physiological plasticity of green compared to the red lettuce regarding its phenolic compounds. They support the photoprotection theory regarding anthocyanins as well as the theory that the deamination activity of phenylalanine ammonia-lyase drives phenylpropanoid synthesis.

Nitrogen Limited Red and Green Leaf Lettuce Accumulate Flavonoid Glycosides, Caffeic Acid Derivatives, and Sucrose while Losing Chlorophylls, Β-Carotene and Xanthophylls

PubMed Central

Becker, Christine; Urlić, Branimir; Jukić Špika, Maja; Kläring, Hans-Peter; Krumbein, Angelika; Baldermann, Susanne; Goreta Ban, Smiljana; Perica, Slavko; Schwarz, Dietmar

2015-01-01

Reduction of nitrogen application in crop production is desirable for ecological and health-related reasons. Interestingly, nitrogen deficiency can lead to enhanced concentrations of polyphenols in plants. The reason for this is still under discussion. The plants’ response to low nitrogen concentration can interact with other factors, for example radiation intensity. We cultivated red and green leaf lettuce hydroponically in a Mediterranean greenhouse, supplying three different levels of nitrogen (12 mM, 3 mM, 0.75 mM), either in full or reduced (-50%) radiation intensity. In both red and green lettuce, we found clear effects of the nitrogen treatments on growth characteristics, phenolic and photosynthetic compounds, nitrogen, nitrate and carbon concentration of the plants. Interestingly, the concentrations of all main flavonoid glycosides, caffeic acid derivatives, and sucrose increased with decreasing nitrogen concentration, whereas those of chlorophylls, β-carotene, neoxanthin, lactucaxanthin, all trans- and cis-violaxanthin decreased. The constitutive concentrations of polyphenols were lower in the green cultivar, but their relative increase was more pronounced than in the red cultivar. The constitutive concentrations of chlorophylls, β-carotene, neoxanthin, all trans- and cis-violaxanthin were similar in red and green lettuce and with decreasing nitrogen concentration they declined to a similar extent in both cultivars. We only detected little influence of the radiation treatments, e.g. on anthocyanin concentration, and hardly any interaction between radiation and nitrogen concentration. Our results imply a greater physiological plasticity of green compared to the red lettuce regarding its phenolic compounds. They support the photoprotection theory regarding anthocyanins as well as the theory that the deamination activity of phenylalanine ammonia-lyase drives phenylpropanoid synthesis. PMID:26569488

Relaxation of heavy species and gas temperature in the afterglow of a N2 microwave discharge

NASA Astrophysics Data System (ADS)

Pintassilgo, Carlos D.; Guerra, Vasco

2017-10-01

In this paper we present a self-consistent kinetic model to study the temporal variation of the gas temperature in the afterglow of a 440 Pa microwave nitrogen discharge operating at 433 MHz in a 3.8 cm diameter tube. The initial conditions in the afterglow are determined by a kinetic model that solves the electron Boltzmann equation coupled to the gas thermal balance equation and a system of rate-balance equations for N2(X 1∑g+, v) molecules, electronically excited states of N2, ground and excited states of atomic nitrogen and the main positive ions. Once the initial concentrations of the heavy species and gas temperature are known, their relaxation in the afterglow is obtained from the solutions to the corresponding time-dependent equations. Modelling predictions are found to be in good agreement with previously measured values for the concentrations of N(4S) atoms and N2(A 3∑u+) molecules, and the radially averaged gas temperature Tg along the afterglow of a microwave discharge in N2 under the same working conditions. It is shown that gas heating in the afterglow comes essentially from the energy transfer involving non-resonant vibration-vibration (V-V) collisions between vibrationally excited nitrogen molecules, as well as from energy exchanges in vibration-translation (V-T) on N2-N collisions. Contribution to the topical issue "Plasma Sources and Plasma Processes (PSPP)", edited by Luis Lemos Alves, Thierry Belmonte and Tiberiu Minea

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

PubMed

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 under the ambient CO2- (360 µmol · mol(-1)) treatment. The order of nitrogen accumulation content in organs was bud > leaf > stem > root. Soil urease activity of both layers increased significantly with the elevation of CO2 concentration in all the nitrogen treatments. Under each CO2 concentration treatment, the soil urease activity in the upper layer (0-20 cm) increased significantly with nitrogen application, while the urease activity under the application of 300 kg · hm(-2) nitrogen was highest in the lower layer (20- 40 cm). The average soil urease activity in the upper layer (0-20 cm) was significantly higher than that in the lower layer (20-40 cm). This study suggested that the cotton dry matter accumulation and nitrogen absorption content were significantly increased in response to the elevated CO2 concentration (540 µmol · mol(-1)) and higher nitrogen addition (300 kg · hm(-2)).

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

NASA Astrophysics Data System (ADS)

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 patterns of the groundwater bodies which fail the good WFD status, the N-surplus or the measured data. The parameters for denitrification and the percolation rate seemed to have a higher model sensitivity than the nitrogen surplus. MoRE was previously validated only for the total N load from groundwater into surface water but the modeling concept for nitrate concentration was seemingly never fitted to observed data and needs refinements. A literature research showed that no groundwater concentrations modeled with MoRE or MONERIS have been published for Germany until now. Instead, only the concentration in percolating water was shown - sometimes misleadingly labeled so that the reader could presume the map displayed groundwater concentrations. According to the MoRE approach, model parameters such as the percolation rate and denitrification intensity are more sensitive than the N surplus. The surplus can indicate only a potential leaching risk, while the actual threat varies substantially with regional soil and climate conditions. Consequently, the use of the nitrogen surplus as a sole indicator for nitrate leaching should be critically examined. For conception of nitrate reduction programs obviously the regionally varying site conditions cannot be disregarded.

Ca2+ Requirement for Aerobic Nitrogen Fixation by Heterocystous Blue-Green Algae 1

PubMed Central

Rodríguez, Herminia; Rivas, Joaquín; Guerrero, Miguel G.; Losada, Manuel

1990-01-01

The requirement of Ca2+ for growth and nitrogen fixation has been investigated in two strains of heterocystous blue-green algae (Anabaena sp. and Anabaena ATCC 33047). With combined nitrogen (nitrate or ammonium) or with N2 under microaerobic conditions, Ca2+ was not required for growth, at least in concentrations greater than traces. In contrast, Ca2+ was required as a macronutrient for growth and nitrogen fixation with air as the nitrogen source. Addition of Ca2+ to an aerobic culture without Ca2+ promoted, after a lag of several hours, development of nitrogenase activity and cell growth. Provision of air to a microaerobic culture in the absence of Ca2+ promoted a drastic drop in nitrogenase activity, which rapidly recovered its initial level upon restoration of microaerobic conditions. Development of nitrogenase activity in response to either Ca2+ or low oxygen tension was dependent on de novo protein synthesis. The role of Ca2+ seems to be related to protection of nitrogenase from inactivation, by conferring heterocysts resistance to oxygen. PMID:16667401

Photo-catalytic decolourisation of toxic dye with N-doped titania: a case study with Acid Blue 25.

PubMed

Chakrabortty, Dhruba; Gupta, Susmita Sen

2013-05-01

Dyes are one of the hazardous water pollutants. Toxic Acid Blue 25, an anthraquinonic dye, has been decolourised by photo-catalysing it with nitrogen doped titania in aqueous medium. The photo catalyst was prepared from 15% TiCl3 and 25% aqueous NH3 solution as precursor. XRD and TEM revealed the formation of well crystalline anatase phase having particle size in the nano-range. BET surface area of the sample was higher than that of pure anatase TiO2. DRS showed higher absorption of radiation in visible range compared to pure anatase TiO2. XPS revealed the presence of nitrogen in N-Ti-O environment. The experimental parameters, namely, photocatalyst dose, initial dye concentration as well as solution pH influence the decolourisation process. At pH 3.0, the N-TiO2 could decolourise almost 100% Acid Blue 25 within one hour. The influence of N-TiO2 dose, initial concentration of Acid Blue 25 and solution pH on adsorption-desorption equilibrium is also studied. The adsorption process follows Lagergren first order kinetics while the modified Langmuir-Hinselwood model is suitably fitted for photocatalytic decolourisation of Acid Blue 25.

Nitrogen transport and transformations in a shallow aquifer receiving wastewater discharge: A mass balance approach

USGS Publications Warehouse

Desimone, Leslie A.; Howes, Brian L.

1998-01-01

Nitrogen transport and transformations were followed over the initial 3 years of development of a plume of wastewater-contaminated groundwater in Cape Cod, Massachusetts. Ammonification and nitrification in the unsaturated zone and ammonium sorption in the saturated zone were predominant, while loss of fixed nitrogen through denitrification was minor. The major effect of transport was the oxidation of discharged organic and inorganic forms to nitrate, which was the dominant nitrogen form in transit to receiving systems. Ammonification and nitrification in the unsaturated zone transformed 16–19% and 50–70%, respectively, of the total nitrogen mass discharged to the land surface during the study but did not attenuate the nitrogen loading. Nitrification in the unsaturated zone also contributed to pH decrease of 2 standard units and to an N2O increase (46–660 µg N/L in the plume). Other processes in the unsaturated zone had little net effect: Ammonium sorption removed <1% of the total discharged nitrogen mass; filtering of particulate organic nitrogen was less than 3%; ammonium and nitrate assimilation was less than 6%; and ammonia volatilization was less than 0.25%. In the saturated zone a central zone of anoxic groundwater (DO ≤ 0.05 mg/L) was first detected 17 months after effluent discharge to the aquifer began, which expanded at about the groundwater-flow velocity. Although nitrate was dominant at the water table, the low, carbon-limited rates of denitrification in the anoxic zone (3.0–9.6 (ng N/cm3)/d) reduced only about 2% of the recharged nitrogen mass to N2. In contrast, ammonium sorption in the saturated zone removed about 16% of the recharged nitrogen mass from the groundwater. Ammonium sorption was primarily limited to anoxic zone, where nitrification was prevented, and was best described by a Langmuir isotherm in which effluent ionic concentrations were simulated. The initial nitrogen load discharged from the groundwater system may depend largely on the growth and stability of the sorbed ammonium pool, which in turn depends on effluent-loading practices, subsurface microbial processes, and saturation of available exchange sites.

Isolation of aluminum-tolerant bacteria capable of nitrogen removal in activated sludge.

PubMed

Ji, Bin; Chen, Wei; Zhu, Lei; Yang, Kai

2016-05-15

Four strains of bacteria capable of withstanding 20mM concentration of aluminum were isolated from activated sludge in a bioreactor. 16S rRNA identification and morphological characteristics indicated that these strains were Chryseobacterium sp. B1, Brevundimonas diminuta B3, Hydrogenophaga sp. B4, and Bacillus cereus B5. Phylogenetic analysis revealed the position and interrelationships of these bacteria. B. diminuta B3 and Hydrogenophaga sp. B4 could achieve nitrate nitrogen removal of 94.0% and 76.8% within 36h of its initial concentration of 148.8 and 151.7mg/L, respectively. Meanwhile, B3 and B4 could degrade ammonia with little nitrite accumulation. Results of this study provide more information about aluminum-resistant bacteria and laid the foundation for aluminum salt when it is simultaneously used for chemical precipitation. Copyright © 2016 Elsevier Ltd. All rights reserved.

3-Nitropropionic acid production by the endophytic Diaporthe citri: Molecular taxonomy, chemical characterization, and quantification under pH variation.

PubMed

Polonio, Julio Cesar; Ribeiro, Marcos Alessandro Dos Santos; Rhoden, Sandro Augusto; Sarragiotto, Maria Helena; Azevedo, João Lúcio; Pamphile, João Alencar

2016-12-01

3-nitropropionic acid (3-NPA) is a nitrogenated compound produced by plants and fungi and has been associated with poisoning episodes in humans, animals, and to induction of Huntington disease symptoms in rats. The production of 3-NPA by endophytes has been reported, but the function and biosynthesis are not well-defined. The specie of endophytic strain G-01 was confirmed as Diaporthe citri using a multilocus sequence analysis, and was verified different concentrations of 3-NPA produced at different initial pHs by these strain. The chemical analysis indicated that 3-NPA was the majority compound present in the crude extracts. The better extraction condition was at an initial pH of 7.0 for 22 d, yielding about 80 % of 3-NPA per mg of extract. It was observed that the concentration of 3-NPA increased after the initial consumption of reduction sugars, indicating that the compound is produced after the high energetic production phase of the fungus. These and other studies demonstrate the production of this compound by plants and endophytic fungi, indicating that 3-NPA may be involved in defence and nutrition systems of endophytes and host plants, and they also might participate in the biogeochemical nitrogen cycle. Copyright © 2016 British Mycological Society. Published by Elsevier Ltd. All rights reserved.

Measurement of Reactive Oxygen Species, Reactive Nitrogen Species, and Redox-Dependent Signaling in the Cardiovascular System

PubMed Central

Griendling, Kathy K.; Touyz, Rhian M.; Zweier, Jay L.; Dikalov, Sergey; Chilian, William; Chen, Yeong-Renn; Harrison, David G.; Bhatnagar, Aruni

2017-01-01

Reactive oxygen species and reactive nitrogen species are biological molecules that play important roles in cardiovascular physiology and contribute to disease initiation, progression, and severity. Because of their ephemeral nature and rapid reactivity, these species are difficult to measure directly with high accuracy and precision. In this statement, we review current methods for measuring these species and the secondary products they generate and suggest approaches for measuring redox status, oxidative stress, and the production of individual reactive oxygen and nitrogen species. We discuss the strengths and limitations of different methods and the relative specificity and suitability of these methods for measuring the concentrations of reactive oxygen and reactive nitrogen species in cells, tissues, and biological fluids. We provide specific guidelines, through expert opinion, for choosing reliable and reproducible assays for different experimental and clinical situations. These guidelines are intended to help investigators and clinical researchers avoid experimental error and ensure high-quality measurements of these important biological species. PMID:27418630

Heterotrophic nitrification and aerobic denitrification by Pseudomonas tolaasii Y-11 without nitrite accumulation during nitrogen conversion.

PubMed

He, Tengxia; Li, Zhenlun; Sun, Quan; Xu, Yi; Ye, Qing

2016-01-01

A hypothermia aerobic nitrite-denitrifying bacterium, Pseudomonas tolaasii strain Y-11, was found to display high removal capabilities for heterotrophic nitrification with ammonium and for aerobic denitrification with nitrate or nitrite nitrogen. When strain Y-11 was cultivated for 4days at 15°C with the initial ammonium, nitrate and nitrite nitrogen concentrations of 209.62, 204.61 and 204.33mg/L (pH 7.2), the ammonium, nitrate and nitrite removal efficiencies were 93.6%, 93.5% and 81.9% without nitrite accumulation, and the corresponding removal rates reached as high as 2.04, 1.99 and 1.74mg/L/h, respectively. Additionally, ammonium was removed mainly during the simultaneous nitrification and denitrification process. All results demonstrate that P. tolaasii strain Y-11 has the particularity to remove ammonium, nitrate and nitrite nitrogen at low temperatures, which guarantees it for future application in winter wastewater treatment. Copyright © 2015 Elsevier Ltd. All rights reserved.

RELATIONSHIPS BETWEEEN NITROGEN LOADING AND CONCENTRATIONS OF NITROGEN AND CHLOROPHYLL IN COASTAL EMBAYMENTS

EPA Science Inventory

We describe results obtained with a simple model that uses loading rates of total nitrogen (TN), defined as dissolved inorganic nitrogen plus dissolved and particulate organic nitrogen, to calculate annually and spatially averaged concentrations of TN in coastal embayments. We al...

Estimates of nitrogen loads entering Long Island Sound from ground water and streams on Long Island, New York, 1985–96

USGS Publications Warehouse

Scorca, Michael P.; Monti, Jack

2001-01-01

Fresh ground water that discharges from the northern part of Long Island's aquifer system to Long Island Sound contains elevated concentrations of nitrogen from agricultural fertilizer, domestic waste and fertilizer, and precipitation. The nitrogen contributes to algal blooms, which consume oxygen as the algae die and decompose. The resulting low dissolved oxygen concentrations (hypoxia) adversely affect plant and animal populations in Long Island Sound.The four major streams on the north shore of Long Island that have long-term discharge and water-quality records were selected for analysis of geographic, long-term, and seasonal trends in nitrogen concentration. Nitrogen concentrations generally decrease eastward among three Nassau County streams, then increase again at the easternmost stream, Nissequogue River in Suffolk County. A long-term (1970-96) increase in total nitrogen concentrations in the Nissequogue River also is evident. Seasonal fluctuations in nitrogen concentrations in all four streams reflect chemical reactions and microbial activity in the stream system, so total nitrogen concentrations in the three easternmost streams generally were lowest during summer and highest in winter, whereas those in the westernmost stream (Glen Cove Creek) were highest during summer and lowest in winter.The nitrogen loads discharged to Long Island Sound from each of the four streams for each year during 1985-96 were calculated from the annual mean total nitrogen concentration and the annual mean discharge. Nissequogue River's annual mean discharges were 3 to 6 times larger than those of Glen Cove and Mill Neck Creeks, and produced the largest annual loads of nitrogen--65 to 149 ton/yr (59,000 to 135,000 kg/yr). Cold Spring Brook had the lowest annual mean discharges and annual mean total nitrogen concentrations of the four streams; its annual mean nitrogen load ranged from 1.2 to 2.8 ton/yr (1,100 to 2,500 kg/yr).The nitrogen load carried to Long Island Sound by shallow ground water from the north shore of Long Island was calculated from simulated shallow-aquifer discharges from Nassau and Suffolk Counties (9,200 and 21,400 Mgal/yr or 34,800,000 and 81,100,000 m3/yr, respectively) and median total nitrogen concentrations at selected wells (2.2 and 4.3 milligrams per liter as N, respectively). The resultant nitrogen load was 84 ton/yr (76,500 kg/yr) for Nassau County and 384 ton/yr (349,000 kg/yr) for Suffolk County.The nitrogen load carried to Long Island Sound by deep ground water from the north shore was calculated from simulated deep-aquifer discharges from Nassau and Suffolk counties (13,200 and 47,300 Mgal/yr or 50,000,000 and 179,000,000 m3/yr, respectively). The median nitrogen concentrations of deep ground water for the two counties were 1.62 and 1.34 mg/L as N, respectively. The resultant nitrogen load from deep-aquifer discharge was 89 ton/yr (81,000 kg/yr) for Nassau County and 265 ton/yr (240,000 kg/yr) for Suffolk County.Nitrogen loads entering Long Island Sound from the shallow aquifer underlying three areas of differing land use along the north shore--a sewered residential area in Nassau County, an unsewered residential area in Suffolk County, and an agricultural area in Suffolk County--were evaluated. The agricultural area contains no major streams and, therefore, produces very little surface runoff to Long Island Sound and substantially greater shallow-aquifer discharge than in the sewered and unsewered areas. Ground water in the agricultural area also had the highest median nitrogen concentration (9.9 mg/L as N) of the three land-use areas and discharged the largest estimated nitrogen load to Long Island Sound--152 ton/yr (138,000 kg/yr), which represents about 40 percent of the estimated total nitrogen load from Suffolk County. Ground water in the sewered area had the lowest nitrogen concentration (1.9 mg/L as N) and discharged the smallest nitrogen load to Long Island Sound--7.28 ton/yr (6,600 kg/yr). The analysis indicates that land use on the north shore of Long Island can greatly affect the nitrogen concentration of water in the shallow aquifer and the resultant nitrogen load discharged to Long Island Sound from ground water.

Nitrogen dioxide exposures inside ice skating rinks.

PubMed Central

Brauer, M; Spengler, J D

1994-01-01

OBJECTIVES. The common operation of fuel-powered resurfacing equipment in enclosed ice skating rinks has the potential for producing high concentrations of carbon monoxide and nitrogen dioxide. Exposures to these gaseous combustion products may adversely affect the health of those inside the rink. Little information is available on pollutant concentrations under normal operating conditions. METHODS. One-week average nitrogen dioxide concentrations in 70 northeastern US rinks were measured with passive samplers during normal winter season conditions. RESULTS. The median nitrogen dioxide level inside rinks was 180 ppb, more than 10 times higher than the median outdoor concentration. One-week average nitrogen dioxide concentrations above 1000 ppb were measured in 10% of the rinks. CONCLUSIONS. Considering that short-term peak concentrations were likely to have reached two to five times the measured 1-week averages, our results suggest that nitrogen dioxide levels were well above short-term air quality guidelines and constitute a public health concern of considerable magnitude. PMID:8129060

Food for folivores: nutritional explanations linking diets to population density.

PubMed

Wallis, Ian R; Edwards, Melanie J; Windley, Hannah; Krockenberger, Andrew K; Felton, Annika; Quenzer, Megan; Ganzhorn, Joerg U; Foley, William J

2012-06-01

Ecologists want to explain why populations of animals are not evenly distributed across landscapes and often turn to nutritional explanations. In seeking to link population attributes with food quality, they often contrast nutritionally positive traits, such as the concentration of nitrogen, against negative ones, such as fibre concentration, by using a ratio of these traits. This specific ratio has attracted attention because it sometimes correlates with the biomass of colobine primates across sites in Asia and Africa. Although empirically successful, we have identified problems with the ratio that may explain why it fails under some conditions to predict colobine biomass. First, available nitrogen, rather than total nitrogen, is nutritionally important, while the presence of tannins is the major factor reducing the availability of nitrogen in browse plant species. Second, tannin complexes inflate measures of fibre. Finally, simple ratios may be unsound statistically because they implicitly assume isometric relationships between variables. We used data on the chemical composition of plants from three continents to examine the relationships between the concentrations of nitrogen, available nitrogen, fibre and tannins in foliage and to evaluate the nitrogen to fibre ratio. Our results suggest that the ratio of the concentration of nitrogen to fibre in leaves does sometimes closely correlate with the concentration of available nitrogen. However, the ratio may give misleading results when leaves contain high concentrations of tannins. The concentration of available nitrogen, which incorporates measures of total nitrogen, dry matter digestibility and tannins, should give a better indication of the nutritional value of leaves for herbivorous mammals that can readily be extrapolated to habitats.

Response of ozone to changes in hydrocarbon and nitrogen oxide concentrations in outdoor smog chambers filled with Los Angeles air

NASA Astrophysics Data System (ADS)

Kelly, Nelson A.; Gunst, Richard F.

During the summer portion of the 1987 Southern California Air Quality Study (SCAQS), outdoor smog chamber experiments were performed on Los Angeles air to determine the response of maximum ozone levels, O 3(max), to changes in the initial concentrations of hydrocarbons, HC, and nitrogen oxides, NO x. These captive-air experiments were conducted in downtown Los Angeles and in the downwind suburb of Claremont. Typically, eight chambers were filled with LA air in the morning. In some chambers the initial HC and/or NO x concentrations were changed by 25% to 50% by adding various combinations of a mixture of HC, clean air, or NO x. The O 3 concentration in each chamber was monitored throughout the day to determine O 3(max). An empirical mathematical model for O 3(max) was developed from regression fits to the initial HC and NO x concentrations and to the average daily temperature at both sites. This is the first time that a mathematical expression for the O 3-precursor relationship and the positive effect of temperature on O 3(max) have been quantified using captive-air experiments. An ozone isopleth diagram prepared from the empirical model was qualitatively similar to those prepared from photochemical mechanisms. This constitutes the first solely empirical corroboration of the O 3 contour shape for Los Angeles. To comply with the Federal Ozone Standard in LA, O 3(max) must be reduced by approximately 50%. Several strategies for reducing O 3(max) by 50% were evaluated using the empirical model. For the average initial conditions that we measured in LA, the most efficient strategy is one that reduces HC by 55-75%, depending on the ambient HC/NO x ratio. Any accompanying reduction in NO x would be counter-productive to the benefits of HC reductions. In fact, reducing HC and NO x simultaneously requires larger percentage reductions for both than the reduction required when HC alone is reduced. The HC-reduction strategy is the most efficient on average, but no single strategy is the optimum every day.

Trends in nitrogen isotope ratios of juvenile winter flounder ...

EPA Pesticide Factsheets

Nitrogen isotope ratios (d 15N) in juvenile winter flounder, Pseudopleuronectes americanus, were used to examine changes in nitrogen inputs to several Rhode Island, USA estuarine systems. Fish were collected over two three-year periods with a ten-year interval between sampling periods (2002-2004 and 2012-2014). During that interval numerous changes to nutrient management practices were initiated in the watersheds of these estuarine systems including the upgrade of several major wastewater treatment facilities that discharge to Narragansett Bay, which significantly reduced nitrogen inputs. Following these reductions, the d 15N values of flounder in several of the systems decreased as expected; however, isotope ratios in fish from upper Narragansett Bay significantly increased. We believe that low d 15N values measured in 2002-2004 were related to concentration-dependant fractionation at this location. Increased d 15N values measured between 2012 and 2014 may indicate reduced fractionation or that changes in wastewater treatment processes altered the nitrogen isotopic ratios of the effluents. This manuscript advances the development of methodology to assess the influence of anthropogenic nitrogen in estuarine systems. Juvenile winter flounder were collected from several estuarine systems along the coast of Rhode Island over two three-year periods and nitrogen isotopes were measured in the muscle tissues of the flounder. The results showed that there was a good cor

Improved fed-batch production of high-purity PHB (poly-3 hydroxy butyrate) by Cupriavidus necator (MTCC 1472) from sucrose-based cheap substrates under response surface-optimized conditions.

PubMed

Dey, Pinaki; Rangarajan, Vivek

2017-10-01

Experimental investigations were carried out for Cupriavidus necator (MTCC 1472)-based improved production of poly-3 hydroxy butyrate (PHB) through induced nitrogen limiting fed-batch cultivation strategies. Initially Plackett-Burman design and response surface methodology were implemented to optimize most influencing process parameters. With optimized process parameter values, continuous feeding strategies ware applied in a 5-l fermenter with table sugar concentration of 100 g/l, nitrogen concentration of 0.12 g/l for fed-batch fermentation with varying dilution rates of 0.02 and 0.046 1/h. To get enriched production of PHB, concentration of the sugar was further increased to 150 and 200 g/l in feeding. Maximum concentrations of PHB achieved were 22.35 and 23.07 g/l at those dilution rates when sugar concentration maintains at 200 g/l in feeding. At maximum concentration of PHB (23.07 g/l), productivity of 0.58 g/l h was achieved with maximum PHB accumulation efficiency up to 64% of the dry weight of biomass. High purity of PHB, close to medical grade was achieved after surfactant hypochlorite extraction method, and it was further confirmed by SEM, EDX, and XRD studies.

Influence of light presence and biomass concentration on nutrient kinetic removal from urban wastewater by Scenedesmus obliquus.

PubMed

Ruiz, J; Arbib, Z; Alvarez-Díaz, P D; Garrido-Pérez, C; Barragán, J; Perales, J A

2014-05-20

This work was aimed at studying the effect of light-darkness and high-low biomass concentrations in the feasibility of removing nitrogen and phosphorus from urban treated wastewater by the microalga Scenedesmus obliquus. Laboratory experiments were conducted in batch, where microalgae were cultured under different initial biomass concentrations (150 and 1500mgSSl(-1)) and light conditions (dark or illuminated). Nutrient uptake was more dependent on internal nutrient content of the biomass than on light presence or biomass concentration. When a maximum nitrogen or phosphorus content in the biomass was reached (around 8% and 2%, respectively), the removal of that nutrient was almost stopped. Biomass concentration affected more than light presence on the nutrient removal rate, increasing significantly with its increase. Light was only required to remove nutrients when the maximum nutrient storage capacity of the cells was reached and further growth was therefore needed. Residence times to maintain a stable biomass concentration, avoiding the washout of the reactor, were much higher than those needed to remove the nutrients from the wastewater. This ability to remove nutrients in the absence of light could lead to new configurations of reactors aimed to wastewater treatment. Copyright © 2014 Elsevier B.V. All rights reserved.

Nitrogen in rock: Occurrences and biogeochemical implications

USGS Publications Warehouse

Holloway, J.M.; Dahlgren, R.A.

2002-01-01

There is a growing interest in the role of bedrock in global nitrogen cycling and potential for increased ecosystem sensitivity to human impacts in terrains with elevated background nitrogen concentrations. Nitrogen-bearing rocks are globally distributed and comprise a potentially large pool of nitrogen in nutrient cycling that is frequently neglected because of a lack of routine analytical methods for quantification. Nitrogen in rock originates as organically bound nitrogen associated with sediment, or in thermal waters representing a mixture of sedimentary, mantle, and meteoric sources of nitrogen. Rock nitrogen concentrations range from trace levels (>200 mg N kg -1) in granites to ecologically significant concentrations exceeding 1000 mg N kg -1 in some sedimentary and metasedimentary rocks. Nitrate deposits accumulated in arid and semi-arid regions are also a large potential pool. Nitrogen in rock has a potentially significant impact on localized nitrogen cycles. Elevated nitrogen concentrations in water and soil have been attributed to weathering of bedrock nitrogen. In some environments, nitrogen released from bedrock may contribute to nitrogen saturation of terrestrial ecosystems (more nitrogen available than required by biota). Nitrogen saturation results in leaching of nitrate to surface and groundwaters, and, where soils are formed from ammonium-rich bedrock, the oxidation of ammonium to nitrate may result in soil acidification, inhibiting revegetation in certain ecosystems. Collectively, studies presented in this article reveal that geologic nitrogen may be a large and reactive pool with potential for amplification of human impacts on nitrogen cycling in terrestrial and aquatic ecosystems.

Water quality of Cedar Creek reservoir in northeast Texas, 1977 to 1984

USGS Publications Warehouse

Leibbrand, Norman F.; Gibbons, Willard J.

1987-01-01

The concentrations of total inorganic nitrogen, total nitrogen, and total phosphorus were largest during summer stagnation in water near the bottom at the deepest sites. At site Ac, the largest total phosphorus concentration was 5.3 milligrams per liter for a bottom sample. The maximum total inorganic nitrogen concentration for the same sample was 2.5 milligrams per liter. Water near the surface of Cedar Creek Reservoir during summer stagnation and throughout the reservoir during winter circulation had total phosphorus and total inorganic nitrogen concentrations of less than 0.1 milligram per liter. Total nitrogen concentrations near the surface ranged from 0.3 to 1.1 milligrams per liter from January 1980 to August 1984.

Nitrogenous compounds changes in emersed oysters: Crassostrea gigas

NASA Astrophysics Data System (ADS)

Rafrafi, Sarra; Uglow, Roger F.

2009-01-01

The effects of emersing oysters ( Crassostrea gigas) for up to 66 h at 4 °C under humid air and nitrogen atmospheres were studied. A significant, gradual body mass loss occurred under nitrogen (8.36 ± 0.85% final weight loss) but no significant loss occurred under humid air (4.92 ± 2.67% final weight loss). Emersion duration and the mantle cavity fluid (MCF) total ammonia (TA) concentration showed a positive, linear relationship ( r2 = 0.73 and 0.74 under humid air and N 2, respectively). The MCF TA and trimethylamine (TMA) contents were also positively related ( r2 = 0.64 and 0.69 under humid air and N 2, respectively). Proline was the most abundant soft tissue free amino acid (71.07 ± 11.8%) in the control group and its concentration did not change significantly under either treatment. The concentration of alanine and valine increased significantly only under humid air. Under N 2, the concentrations of valine and lysine increased significantly and aspartate decreased significantly. Succinate showed a large increase during the first 6 h of emersion under both treatments but significantly more was accumulated in the N 2-exposed group (4.2-fold increase and 8.1-fold increase for the humid air- and N 2-exposed groups, respectively). The succinate concentration difference remained higher in the N 2-treated groups but, in the final 24 h, levels decreased again (quadratic regressions of r2 = 0.97 and 0.95 under humid air and N 2, respectively). Although the trend of succinate accumulation was similar under both treatments, the groups held under nitrogen did not gape (whereas those under humid air did). It is concluded that the implications of gaping behaviour on succinate accumulation in the initial hours of emersion have considerable ecological significance for oysters which occupy habitats in which they may become emersed for some hours naturally. Gaping behaviour also has considerable commercial implications because emersion occurs frequently during the marketing of live oysters.

Nitrogen dynamics in the tidal freshwater Potomac River, Maryland and Virginia, water years 1979-81

USGS Publications Warehouse

Shultz, David J.

1989-01-01

On an annual basis, river-supplied nitrate is the predominant form of nitrogen supplied to the tidal Potomac River from external sources. Much of the nitrate is associated with high flows that have rapid transit times through the tidal river. The Blue Plains Sewage-Treatment Plant (STP) at Washington, D.C., is the greatest source of all nitrogen species during low-flow periods. Prior to the fall of 1980, ammonia concentrations in depth-integrated, composited water samples were greatest (more than 1.00 mg/L (milligram per liter) as nitrogen) during summer periods near Alexandria, Va., because of loading from the nearby Blue Plains STP and reduced river discharge. After the fall of 1980, initiation of advanced wastewater treatment at the Blue Plains STP reduced ammonia loading to the river by 90 percent and increased nitrate loading by a similar percentage. As a result, concentrations of ammonia during the 1981 low-flow period were less than 0.20 mg/L as nitrogen at Alexandria, while nitrate concentrations were greater than 1.50 mg/L as nitrogen. Concentrations of ammonia and nitrate at Alexandria were shown to be reasonably predictable by use of a simple dilution model that considers only loading from Chain Bridge and the Blue Plains STP. This apparently is the result of the short residence time through the Chain Bridge-to-Alexandria section of the tidal Potomac River, which precludes significant biological alterations. In marked contrast, the residence times of water parcels in the tidal Potomac River from Alexandria to Quantico, Va., are much greater because of the geometry of the reach. Biological nitrogen-cycle transformation processes affect nitrogen-species concentrations to a greater extent in this reach, especially during summer low-flow periods. Mass-balance calculations that separate changes in transport mass from biological transformations indicatethat the tidal Potomac River was a net sink for all the nitrogen constituents during the 1980 and 1981 summer low-flow periods. However, during the 1980-81 winter period, some ammonia and nitrate was transported out of the tidal Potomac River into the transition zone. Despite the reduced availability of ammonia, nitrogen-15 uptake studies showed that phytoplankton preferred ammonia to nitrate unless ammonia concentrations were less than 0.10 mg/L as nitrogen. Nitrification-rate studies during 1981 using a carbon-14 uptake technique indicate that rates did not vary with sample location, except for one sample from the head of the tidal river, where the rates were much higher. The numbers of Nitrobacter bacteria were highest in samples from near the Blue Plains STP and were greater than the numbers of Nitrosomonas bacteria. The predominance of Nitrobacter bacteria seemed to be associated with advanced wastewater treatment at the Blue Plains STP. Before advanced wastewater treatment, Nitrosomonas were numerically predominant and had the largest numbers near the Blue Plains STP. These results could be due to (1) loading of nitrifying bacteria in the Blue Plains sewage effluent that had been inhibited from further growth by an inhibitory substance or (2) the method used to measure nitrification rates, which measured only the ammonia oxidation stage; it is not possible to reject either mechanism on the basis of the data available. Process models were used in conjunction with mass-balance determinations and individual process studies to estimate rates of processes that were not directly measured. It is estimated that denitrification removed 10 times as much nitrate from the water column during the summer of 1981 as during the summer of 1980. Sedimentation of particulate nitrogen is estimated to be the largest sink for nitrogen from the water column and was approximately equal to the external annual loading of all nitrogen constituents on a daily basis. In summer, when river flows usually are low, the tidal Potomac River appears to be a partially closed system rather tha

Water quality transformations during soil aquifer treatment at the Mesa Northwest Water Reclamation Plant, USA.

PubMed

Fox, P; Narayanaswamy, K; Genz, A; Drewes, J E

2001-01-01

Water quality transformations during soil aquifer treatment at the Mesa Northwest Water Reclamation Plant (NWWRP) were evaluated by sampling a network of groundwater monitoring wells located within the reclaimed water plume. The Mesa Northwest Water Reclamation Plant has used soil aquifer treatment (SAT) since it began operation in 1990 and the recovery of reclaimed water from the impacted groundwater has been minimal. Groundwater samples obtained represent travel times from several days to greater than five years. Samples were analyzed for a wide range of organic and inorganic constituents. Sulfate was used as a tracer to estimate travel times and define reclaimed water plume movement. Dissolved organic carbon concentrations were reduced to approximately 1 mg/L after 12 to 24 months of soil aquifer treatment with an applied DOC concentration from the NWWRP of 5 to 7 mg/L. The specific ultraviolet absorbance (SUVA) increased during initial soil aquifer treatment on a time-scale of days and then decreased as longer term soil aquifer treatment removed UV absorbing compounds. The trihalomethane formation potential (THMFP) was a function of the dissolved organic carbon concentration and ranged from 50 to 65 micrograms THMFP/mg DOC. Analysis of trace organics revealed that the majority of trace organics were removed as DOC was removed with the exception of organic iodine. The majority of nitrogen was applied as nitrate-nitrogen and the reclaimed water plume had lower nitrate-nitrogen concentrations as compared to the background groundwater. The average dissolved organic carbon concentrations in the reclaimed water plume were less than 50% of the drinking water dissolved organic concentrations from which the reclaimed water originated.

Nox control for high nitric oxide concentration flows through combustion-driven reduction

DOEpatents

Yeh, James T.; Ekmann, James M.; Pennline, Henry W.; Drummond, Charles J.

1989-01-01

An improved method for removing nitrogen oxides from concentrated waste gas streams, in which nitrogen oxides are ignited with a carbonaceous material in the presence of substoichiometric quantities of a primary oxidant, such as air. Additionally, reductants may be ignited along with the nitrogen oxides, carbonaceous material and primary oxidant to achieve greater reduction of nitrogen oxides. A scrubber and regeneration system may also be included to generate a concentrated stream of nitrogen oxides from flue gases for reduction using this method.

Adsorption of protein GlnB of Herbaspirillum seropedicae on Si(111) investigated by AFM and XPS.

PubMed

Lubambo, A F; Benelli, E M; Klein, J; Schreiner, W; Camargo, P C

2006-01-01

The protein GlnB-Hs (GlnB of Herbaspirillum seropedicae) in diazotroph micro-organisms signalizes levels of nitrogen, carbon, and energy for a series of proteins involved in the regulation of expression and control of the activity of nitrogenase complex that converts atmospheric nitrogen in ammonia, resulting in biological nitrogen fixation. Its structure has already been determined by X-ray diffraction, revealing a trimer of (36 kDa) with lateral cavities having hydrophilic boundaries. The interactions of GlnB-Hs with the well-known Si(111) surface were investigated for different incubation times, protein concentrations in initial solution, deposition conditions, and substrate initial state. The protein solution was deposited on Si(111) and dried under controlled conditions. An atomic force microscope operating in dynamic mode shows images of circular, linear, and more complex donut-shaped protein arrangement, and also filament types of organization, which vary from a few nanometers to micrometers. Apparently, the filament formation was favored because of protein surface polarity when in contact with the silicon surface, following some specific orientation. The spin-coating technique was successfully used to obtain more uniform surface covering.

Investigating a physical basis for spectroscopic estimates of leaf nitrogen concentration

USGS Publications Warehouse

Kokaly, R.F.

2001-01-01

The reflectance spectra of dried and ground plant foliage are examined for changes directly due to increasing nitrogen concentration. A broadening of the 2.1-??m absorption feature is observed as nitrogen concentration increases. The broadening is shown to arise from two absorptions at 2.054 ??m and 2.172 ??m. The wavelength positions of these absorptions coincide with the absorption characteristics of the nitrogen-containing amide bonds in proteins. The observed presence of these absorption features in the reflectance spectra of dried foliage is suggested to form a physical basis for high correlations established by stepwise multiple linear regression techniques between the reflectance of dry plant samples and their nitrogen concentration. The consistent change in the 2.1-??m absorption feature as nitrogen increases and the offset position of protein absorptions compared to those of other plant components together indicate that a generally applicable algorithm may be developed for spectroscopic estimates of nitrogen concentration from the reflectance spectra of dried plant foliage samples. ?? 2001 Published by Elsevier Science Ireland Ltd.

Anammox moving bed biofilm reactor pilot at the 26th Ward wastewater treatment plants in Brooklyn, New York: start-up, biofilm population diversity and performance optimization.

PubMed

Mehrdad, M; Park, H; Ramalingam, K; Fillos, J; Beckmann, K; Deur, A; Chandran, K

2014-01-01

New York City Environmental Protection in conjunction with City College of New York assessed the application of the anammox process in the reject water treatment using a moving bed biofilm reactor (MBBR) located at the 26th Ward wastewater treatment plant, in Brooklyn, NY. The single-stage nitritation/anammox MBBR was seeded with activated sludge and consequently was enriched with its own 'homegrown' anammox bacteria (AMX). Objectives of this study included collection of additional process kinetic and operating data and assessment of the effect of nitrogen loading rates on process performance. The initial target total inorganic nitrogen removal of 70% was limited by the low alkalinity concentration available in the influent reject water. Higher removals were achieved after supplementing the alkalinity by adding sodium hydroxide. Throughout startup and process optimization, quantitative real-time polymerase chain reaction (qPCR) analyses were used for monitoring the relevant species enriched in the biofilm and in the suspension. Maximum nitrogen removal rate was achieved by stimulating the growth of a thick biofilm on the carriers, and controlling the concentration of dissolved oxygen in the bulk flow and the nitrogen loading rates per surface area; all three appear to have contributed in suppressing nitrite-oxidizing bacteria activity while enriching AMX density within the biofilm.

Removal of ammonia nitrogen from leachate of Muribeca municipal solid waste landfill, Pernambuco, Brazil, using natural zeolite as part of a biochemical system.

PubMed

Lins, Cecilia Maria M S; Alves, Maria Cristina M; Campos, Juacyara C; Silva, Fabrícia Maria S; Jucá, José Fernando T; Lins, Eduardo Antonio M

2015-01-01

The inadequate disposal of leachate is one of the key factors in the environmental impact of urban solid waste landfills in Brazil. Among the compounds present in the leachates from Brazilian landfills, ammonia nitrogen is notable for its high concentrations. The purpose of this study was to assess the efficiency of a permeable reactive barrier filled with a natural zeolite, which is part of a biochemical system for the tertiary treatment of the leachate from Muribeca Municipal Solid Waste Landfill in Pernambuco, Brazil, to reduce its ammonia nitrogen concentration. This investigation initially consisted of kinetic studies and batch equilibrium tests on the natural zeolite to construct the sorption isotherms, which showed a high sorption capacity, with an average of 12.4 mg NH4+.L(-1), a value close to the sorption rates found for the aqueous ammonium chloride solution. A permeable reactive barrier consisting of natural zeolite, as simulated by the column test, was efficient in removing the ammonia nitrogen present in the leachate pretreated with calcium hydroxide. Nevertheless, the regenerated zeolite did not satisfactorily maintain the sorption properties of the natural zeolite, and an analysis of their cation-exchange properties showed a reduced capacity of 54 meq per 100 g for the regenerated zeolite compared to 150 meq per 100 g for the natural zeolite.

National-Scale Air Quality Data Assessment: Initial Findings from the Near-Road NO2 Monitoring Program

NASA Astrophysics Data System (ADS)

DeWinter, J. L.

2015-12-01

In 2010, the U.S. Environmental Protection Agency (EPA) revised the National Ambient Air Quality Standards (NAAQS) for nitrogen dioxide (NO2) to include a primary health-based standard for hourly NO2. NO2 is a reactive gas that is emitted from motor vehicles, such as cars, trucks, and off-road equipment, as well as non-mobile sources, and is known to adversely affect human respiratory health. In conjunction with the NAAQS revision, EPA has mandated air quality monitoring next to selected major roadways throughout the United States that are in large urban areas where peak hourly NO2 concentrations are expected. Monitoring began in phases during 2012-2015 and included nitrogen dioxide (NO2), carbon monoxide (CO), and particulate matter smaller than 2.5 microns (PM2.5) at 40 monitoring sites nationwide. We conducted a national-scale review of near-road air pollutant concentrations, identified areas where high concentrations of NO2, PM2.5, and CO occurred, and evaluated how concentrations varied by factors such as location, distance to roadway, fleet mix characteristics, and traffic volume. We present the findings from our national near-road data assessment for the 2014 monitoring year.

Simultaneous Heterotrophic Nitrification and Aerobic Denitrification by Chryseobacterium sp. R31 Isolated from Abattoir Wastewater

PubMed Central

Kundu, Pradyut; Pramanik, Arnab; Dasgupta, Arpita; Mukherjee, Somnath; Mukherjee, Joydeep

2014-01-01

A heterotrophic carbon utilizing microbe (R31) capable of simultaneous nitrification and denitrification (SND) was isolated from wastewater of an Indian slaughterhouse. From an initial COD value of 583.0 mg/L, 95.54% was removed whilst, from a starting NH4 +-N concentration of 55.7 mg/L, 95.87% was removed after 48 h contact. The concentrations of the intermediates hydroxylamine, nitrite, and nitrate were low, thus ensuring nitrogen removal. Aerobic denitrification occurring during ammonium removal by R31 was confirmed by utilization of both nitrate and nitrite as nitrogen substrates. Glucose and succinate were superior while acetate and citrate were poor substrates for nitrogen removal. Molecular phylogenetic identification, supported by chemotaxonomic and physiological properties, assigned R31 as a close relative of Chryseobacterium haifense. The NH4 +-N utilization rate and growth of strain R31 were found to be higher at C/N = 10 in comparison to those achieved with C/N ratios of 5 and 20. Monod kinetic coefficients, half saturation concentration (K s), maximum rate of substrate utilization (k), yield coefficient, (Y) and endogenous decay coefficient (K d) indicated potential application of R31 in large-scale SND process. This is the first report on concomitant carbon oxidation, nitrification, and denitrification in the genus Chryseobacterium and the associated kinetic coefficients. PMID:24991552

Effects of nitrogen fertilizers on the growth and nitrate content of lettuce (Lactuca sativa L.).

PubMed

Liu, Cheng-Wei; Sung, Yu; Chen, Bo-Ching; Lai, Hung-Yu

2014-04-22

Nitrogen is an essential element for plant growth and development; however, due to environmental pollution, high nitrate concentrations accumulate in the edible parts of these leafy vegetables, particularly if excessive nitrogen fertilizer has been applied. Consuming these crops can harm human health; thus, developing a suitable strategy for the agricultural application of nitrogen fertilizer is important. Organic, inorganic, and liquid fertilizers were utilized in this study to investigate their effect on nitrate concentrations and lettuce growth. The results of this pot experiment show that the total nitrogen concentration in soil and the nitrate concentration in lettuce increased as the amount of nitrogen fertilizer increased. If the recommended amount of inorganic fertilizer (200 kg·N·ha⁻¹) is used as a standard of comparison, lettuce augmented with organic fertilizers (200 kg·N·ha⁻¹) have significantly longer and wider leaves, higher shoot, and lower concentrations of nitrate.

Effects of Nitrogen Fertilizers on the Growth and Nitrate Content of Lettuce (Lactuca sativa L.)

PubMed Central

Liu, Cheng-Wei; Sung, Yu; Chen, Bo-Ching; Lai, Hung-Yu

2014-01-01

Nitrogen is an essential element for plant growth and development; however, due to environmental pollution, high nitrate concentrations accumulate in the edible parts of these leafy vegetables, particularly if excessive nitrogen fertilizer has been applied. Consuming these crops can harm human health; thus, developing a suitable strategy for the agricultural application of nitrogen fertilizer is important. Organic, inorganic, and liquid fertilizers were utilized in this study to investigate their effect on nitrate concentrations and lettuce growth. The results of this pot experiment show that the total nitrogen concentration in soil and the nitrate concentration in lettuce increased as the amount of nitrogen fertilizer increased. If the recommended amount of inorganic fertilizer (200 kg·N·ha−1) is used as a standard of comparison, lettuce augmented with organic fertilizers (200 kg·N·ha−1) have significantly longer and wider leaves, higher shoot, and lower concentrations of nitrate. PMID:24758896

Different removal behaviours of multiple trace antibiotics in municipal wastewater chlorination.

PubMed

Li, Bing; Zhang, Tong

2013-06-01

The chlorination behaviours of 12 antibiotics belonging to six classes at environmentally relevant concentrations were systematically examined under typical conditions relevant to municipal wastewater chlorination. Cefotaxime, cefalexin, ampicillin and tetracycline were completely removed under all three initial free chlorine dosages (5 mg/L, 10 mg/L, and 15 mg/L). The removal efficiencies of sulphamethoxazole, sulphadiazine, roxithromycin, anhydro-erythromycin, ofloxacin, and trimethoprim were closely correlated to the residual free chlorine concentration, and no further significant mass removal was observed after the residual free chlorine concentration decreased to less than ≈ 0.75 mg/L. Ammonia plays a critical role during chlorination because of its competition with antibiotics for free chlorine to form combined chlorine, which reacts slowly with these antibiotics. Except for norfloxacin and ciprofloxacin, the removal behaviours of the 10 other target antibiotics under ammonia nitrogen concentrations ranging from 2 to 15 mg/L were characterised by a rapid initial removal rate upon contact with free chlorine during the first 5 s-1 min (depending on the specific antibiotic and ammonia nitrogen concentration) and then a much slower removal rate. Free chlorine was responsible for the reaction with antibiotics during the rapid stage (first 5 s-1 min), whereas combined chlorine reacted with antibiotics in the subsequent slow stage. Combined chlorine can remove norfloxacin and ciprofloxacin at a relatively faster rate. The presence of suspended solids at 30 mg/L slightly decreased the antibiotic removal rate. The kinetic rate constants decreased by 2.1-13.9%, while the half-lives increased by 2.0-15.0% compared to those of a 0 mg/L suspended solid for the target antibiotics. Copyright © 2013 Elsevier Ltd. All rights reserved.

Biodegradation of 2,4,6-trinitrophenol by Rhodococcus sp. isolated from a picric acid-contaminated soil.

PubMed

Shen, Jinyou; Zhang, Jianfa; Zuo, Yi; Wang, Lianjun; Sun, Xiuyun; Li, Jiansheng; Han, Weiqing; He, Rui

2009-04-30

A picric acid-degrading bacterium, strain NJUST16, was isolated from a soil contaminated by picric acid and identified as a member of Rhodococcus sp. based on 16S rRNA sequence. The degradation assays suggested that the strain NJUST16 could utilize picric acid as the sole source of carbon, nitrogen and energy. The isolate grew optimally at 30 degrees C and initial pH 7.0-7.5 in the mineral salts medium supplemented with picric acid. It was basically consistent with degradation of picric acid by the isolate. Addition of nitrogen sources such as yeast extract and peptone accelerated the degradation of picric acid. However, the stimulation was concentration dependent. The degradation was accompanied by release of stoichiometric amount of nitrite and acidification. The degradation of picric acid at relatively high concentrations (>3.93 mM) demonstrated that the degradation was both pH and nitrite dependent. Neutral and slightly basic pH was crucial to achieve high concentrations of picric acid degradation by the NJUST16 strain.

Initial nitrogen enrichment conditions determines variations in nitrogen substrate utilization by heterotrophic bacterial isolates.

PubMed

Ghosh, Suchismita; Ayayee, Paul A; Valverde-Barrantes, Oscar J; Blackwood, Christopher B; Royer, Todd V; Leff, Laura G

2017-04-04

The nitrogen (N) cycle consists of complex microbe-mediated transformations driven by a variety of factors, including diversity and concentrations of N compounds. In this study, we examined taxonomic diversity and N substrate utilization by heterotrophic bacteria isolated from streams under complex and simple N-enrichment conditions. Diversity estimates differed among isolates from the enrichments, but no significant composition were detected. Substrate utilization and substrate range of bacterial assemblages differed within and among enrichments types, and not simply between simple and complex N-enrichments. N substrate use patterns differed between isolates from some complex and simple N-enrichments while others were unexpectedly similar. Taxonomic composition of isolates did not differ among enrichments and was unrelated to N use suggesting strong functional redundancy. Ultimately, our results imply that the available N pool influences physiology and selects for bacteria with various abilities that are unrelated to their taxonomic affiliation.

Pre- and post-impoundment nitrogen in the lower Missouri River

USGS Publications Warehouse

Blevins, Dale W.; Wilkison, Donald H.; Niesen, Shelley L.

2013-01-01

Large water-sample sets collected from 1899 through 1902, 1907, and in the early 1950s allow comparisons of pre-impoundment and post-impoundment (1969 through 2008) nitrogen concentrations in the lower Missouri River. Although urban wastes were not large enough to detectably increase annual loads of total nitrogen at the beginning of the 20th century, carcass waste, stock-yard manure, and untreated human wastes measurably increased ammonia and organic-nitrogen concentrations during low flows. Average total-nitrogen concentrations in both periods were about 2.5 mg/l, but much of the particulate-organic nitrogen, which was the dominant form of nitrogen around 1900, has been replaced by nitrate. This change in speciation was caused by the nearly 80% decrease in suspended-sediment concentrations that occurred after impoundment, modern agriculture, drainage of riparian wetlands, and sewage treatment. Nevertheless, bioavailable nitrogen has not been low enough to limit primary production in the Missouri River since the beginning of the 20th century. Nitrate concentrations have increased more rapidly from 2000 through 2008 (5 to 12% per year), thus increasing bioavailable nitrogen delivered to the Mississippi River and affecting Gulf Coast hypoxia. The increase in nitrate concentrations with distance downstream is much greater during the post-impoundment period. If strategies to decrease total-nitrogen loads focus on particulate N, substantial decreases will be difficult because particulate nitrogen is now only 23% of total nitrogen in the Missouri River. A strategy aimed at decreasing particulates also could further exacerbate land loss along the Gulf of Mexico, which has been sediment starved since Missouri River impoundment. In contrast, strategies or benchmarks aimed at decreasing nitrate loads could substantially decrease nitrogen loadings because nitrates now constitute over half of the Missouri's nitrogen input to the Mississippi. Ongoing restoration and creation of wetlands along the Missouri River could be part of such a nitrate-reduction strategy. Published 2013. This article is a U.S. Government work and is in the public domain in the USA.

40 CFR 52.277 - Oxides of nitrogen, combustion gas concentration limitations.

Code of Federal Regulations, 2010 CFR

2010-07-01

... 40 Protection of Environment 3 2010-07-01 2010-07-01 false Oxides of nitrogen, combustion gas concentration limitations. 52.277 Section 52.277 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY... Oxides of nitrogen, combustion gas concentration limitations. (a) The following rules are being retained...

40 CFR 52.277 - Oxides of nitrogen, combustion gas concentration limitations.

Code of Federal Regulations, 2014 CFR

2014-07-01

... 40 Protection of Environment 3 2014-07-01 2014-07-01 false Oxides of nitrogen, combustion gas concentration limitations. 52.277 Section 52.277 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY... Oxides of nitrogen, combustion gas concentration limitations. (a) The following rules are being retained...

40 CFR 52.277 - Oxides of nitrogen, combustion gas concentration limitations.

Code of Federal Regulations, 2011 CFR

2011-07-01

... 40 Protection of Environment 3 2011-07-01 2011-07-01 false Oxides of nitrogen, combustion gas concentration limitations. 52.277 Section 52.277 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY... Oxides of nitrogen, combustion gas concentration limitations. (a) The following rules are being retained...

40 CFR 52.277 - Oxides of nitrogen, combustion gas concentration limitations.

Code of Federal Regulations, 2012 CFR

2012-07-01

... 40 Protection of Environment 3 2012-07-01 2012-07-01 false Oxides of nitrogen, combustion gas concentration limitations. 52.277 Section 52.277 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY... Oxides of nitrogen, combustion gas concentration limitations. (a) The following rules are being retained...

40 CFR 52.277 - Oxides of nitrogen, combustion gas concentration limitations.

Code of Federal Regulations, 2013 CFR

2013-07-01

... 40 Protection of Environment 3 2013-07-01 2013-07-01 false Oxides of nitrogen, combustion gas concentration limitations. 52.277 Section 52.277 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY... Oxides of nitrogen, combustion gas concentration limitations. (a) The following rules are being retained...

Estimating soil solution nitrate concentration from dielectric spectra using PLS analysis

USDA-ARS?s Scientific Manuscript database

Fast and reliable methods for in situ monitoring of soil nitrate-nitrogen concentration are vital for reducing nitrate-nitrogen losses to ground and surface waters from agricultural systems. While several studies have been done to indirectly estimate nitrate-nitrogen concentration from time domain s...

SPATIAL AND TEMPORAL VARIATION IN NITROGEN CONCENTRATIONS AND PHYTOPLANKTON IN THREE NORTHWEST FLORIDA BAYOUS

EPA Science Inventory

Nitrogen concentrations are important indicators of the condition of the estuarine waters of the northern Gulf of Mexico. Elevated levels of inorganic nitrogen as ammonia, nitrite, and nitrate have been associated with increased concentrations of chlorophyll a in the water column...

SEMICONDUCTOR TECHNOLOGY: Influence of nitrogen dose on the charge density of nitrogen-implanted buried oxide in SOI wafers

NASA Astrophysics Data System (ADS)

Zhongshan, Zheng; Zhongli, Liu; Ning, Li; Guohua, Li; Enxia, Zhang

2010-02-01

To harden silicon-on-insulator (SOI) wafers fabricated using separation by implanted oxygen (SIMOX) to total-dose irradiation, the technique of nitrogen implantation into the buried oxide (BOX) layer of SIMOX wafers can be used. However, in this work, it has been found that all the nitrogen-implanted BOX layers reveal greater initial positive charge densities, which increased with increasing nitrogen implantation dose. Also, the results indicate that excessively large nitrogen implantation dose reduced the radiation tolerance of BOX for its high initial positive charge density. The bigger initial positive charge densities can be ascribed to the accumulation of implanted nitrogen near the Si-BOX interface after annealing. On the other hand, in our work, it has also been observed that, unlike nitrogen-implanted BOX, all the fluorine-implanted BOX layers show a negative charge density. To obtain the initial charge densities of the BOX layers, the tested samples were fabricated with a metal-BOX-silicon (MBS) structure based on SIMOX wafers for high-frequency capacitance-voltage (C-V) analysis.

Production of ethanol and arabitol by Debaryomyces nepalensis: influence of process parameters

PubMed Central

2013-01-01

Debaryomyces nepalensis, osmotolerant yeast isolated from rotten apple, is known to utilize both hexoses and pentoses and produce industrially important metabolites like ethanol, xylitol and arabitol. In the present study, the effect of different growth substrates, trace elements, nitrogen concentration and initial pH on growth and formation of ethanol and arabitol were examined. Optimum conditions for maximizing the product yields were established: glucose as carbon source, an initial pH of 6.0, 6 g/L of ammonium sulphate and addition of micronutrients. Under these best suited conditions, a concentration of 11g/L of arabitol and 19 g/L of ethanol was obtained in shake flask fermentations. The fermentation was scaled up to 2.5 L bioreactor and the influence of aeration, agitation and initial substrate concentration was also determined. Under optimal conditions (150 g/L glucose, 400 rpm and 0.5 vvm) ethanol concentration reached 52 g/L, which corresponds to a yield of 0.34 g/g and volumetric productivity of 0.28 g/L/h, whereas arabitol production reached a maximum of 14 g/L with a yield and volumetric productivity of 0.1 g/g and 0.07 g/L/h respectively. PMID:23659479

Methanol Droplet Extinction in Carbon-Dioxide-Enriched Environments in Microgravity

NASA Technical Reports Server (NTRS)

Hicks, Michael C.; Nayagam, Vedha; Williams, Forman A.

2010-01-01

Diffusive extinction of methanol droplets with initial diameters between 1.25 mm and 1.72 mm, burning in a quiescent microgravity environment at one atmosphere pressure, was obtained experimentally for varying levels of ambient carbon-dioxide concentrations with a fixed oxygen concentration of 21% and a balance of nitrogen. These experiments serve as precursors to those which are beginning to be performed on the International Space Station and are motivated by the need to understand the effectiveness of carbon-dioxide as a fire suppressant in low-gravity environments. In these experiments, the flame standoff distance, droplet diameter, and flame radiation are measured as functions of time. The results show that the droplet extinction diameter depends on both the initial droplet diameter and the ambient concentration of carbon dioxide. Increasing the initial droplet diameter leads to an increased extinction diameter, while increasing the carbon-dioxide concentration leads to a slight decrease in the extinction diameter. These results are interpreted using a critical Damk hler number for extinction as predicted by an earlier theory, which is extended here to be applicable in the presence of effects of heat conduction along the droplet support fibers and of the volume occupied by the support beads

Temporal-spatial variations and influencing factors of nitrogen in the shallow groundwater of the nearshore vegetable field of Erhai Lake, China.

PubMed

Chen, Anqiang; Lei, Baokun; Hu, Wanli; Wang, Hongyuan; Zhai, Limei; Mao, Yanting; Fu, Bin; Zhang, Dan

2018-02-01

Nitrogen export from the nearshore vegetable field of Erhai Lake seriously threatens the water quality of Erhai Lake, which is the second largest highland freshwater lake in Yunnan Province, China. Among the nitrogen flows into Erhai Lake, shallow groundwater migration is a major pathway. The nitrogen variation and influencing factors in the shallow groundwater of the nearshore vegetable field of Erhai Lake are not well documented. A 2-year field experiment was conducted to determine the concentrations of nitrogen species in the shallow groundwater and their influencing factors in the nearshore vegetable field of Erhai Lake. The results showed that concentrations of TN, NO 3 - -N, and NO 2 - -N gradually increased with increasing elevation and distance from Erhai Lake, but the opposite was observed for NH 4 + -N in the shallow groundwater. The concentrations of nitrogen species in the rainy season were greater than those in the dry season. NO 3 - -N accounted for more than 79% of total nitrogen in shallow groundwater. Redundancy analysis showed that more than 70% of the temporal and spatial variations of nitrogen concentrations in the shallow groundwater were explained by shallow groundwater depth, and only approximately 10% of variation was explained by the factors of soil porosity, silt clay content of soil, and NH 4 + -N and NO 3 - -N concentrations of soil (p < 0.05). The shallow groundwater depth had more notable effects on nitrogen concentrations in the shallow groundwater than other factors. This result will strongly support the need for further research regarding the management practices for reducing nitrogen concentrations in shallow groundwater.

Tracing Nitrate Contributions to Streams During Varying Flow Regimes at the Sleepers River Research Watershed, Vermont, USA

NASA Astrophysics Data System (ADS)

Sebestyen, S. D.; Shanley, J. B.; Boyer, E. W.; Ohte, N.; Doctor, D. H.; Kendall, C.

2003-12-01

Quantifying sources and transformations of nitrate in headwater catchments is fundamental to understanding the movement of nitrogen to streams. At the Sleepers River Research Watershed in northeastern Vermont (USA), we are using multiple chemical tracer and mixing model approaches to quantify sources and transport of nitrate to streams under varying flow regimes. We sampled streams, lysimeters, and wells at nested locations from the headwaters to the outlet of the 41 ha W-9 watershed under the entire range of flow regimes observed throughout 2002-2003, including baseflow and multiple events (stormflow and snowmelt). Our results suggest that nitrogen sources, and consequently stream nitrate concentrations, are rapidly regenerated during several weeks of baseflow and nitrogen is flushed from the watershed by stormflow events that follow baseflow periods. Both basic chemistry data (anions, cations, & dissolved organic carbon) and isotopic data (nitrate, dissolved organic carbon, and dissolved inorganic carbon) indicate that nitrogen source contributions vary depending upon the extent of saturation in the watershed, the initiation of shallow subsurface water inputs, and other hydrological processes. Stream nitrate concentrations typically peak with discharge and are higher on the falling than the rising limb of the hydrograph. Our data also indicate the importance of terrestrial and aquatic biogeochemical processes, in addition to hydrological connectivity in controlling how nitrate moves from the terrestrial landscape to streams. Our detailed sampling data from multiple flow regimes are helping to identify and quantify the "hot spots" and "hot moments" of biogeochemical and hydrological processes that control nitrogen fluxes in streams.

Fiber source and inclusion level affects characteristics of excreta from growing pigs

PubMed Central

Ndou, Saymore Petros; Bakare, Archibold Garikayi

2018-01-01

Objective The objective of the study was to determine the influence of varying fibrous diets on fecal characteristics of growing pigs. Methods A total of 104 pigs (initial weight 18±2.0 kg) were used in the study. They were housed in individual pens and fed on diets containing maize cob, grass hay, lucerne hay, maize stover, and sunflower husk. These fibers were included at 0, 80, 160, 240, 320 and 400 g/kg. Fecal and urine samples were collected. Results Fecal output was largest amongst pigs fed on diets containing grass hay and maize stover (p<0.05). Nitrogen content was highest in feces from pigs fed on sunflower husk (p< 0.05). Pigs fed on diets containing maize stover and maize cobs produced the largest concentrations of short chain fatty acids. Acetate concentration was high in feces of pigs fed maize stover than those fed grass hay and lucerne hay (p<0.05). As the level of fiber inclusion increased, fecal consistency and nitrogen content increased linearly (p<0.05). Urea nitrogen decreased as the inclusion level increased across all the fibers (p<0.05), with maize cobs containing the largest content of urea nitrogen. As dietary fiber content increased, fecal nitrogen content also increased (p<0.05). Conclusion It was concluded that different fiber sources influence fecal characteristics, thereby having different implications on pig waste management. It is vital to monitor fiber inclusion thresholds so as to easily manage environmental pollutants such as butyrate that contribute to odors. PMID:26954189

Nitrogen concentration and isotope dataset for environmental samples from 2012 and 2013, Barrow, Alaska

DOE Data Explorer

Jeff Heikoop; Heather Throckmorton

2015-05-15

Dataset includes nitrate concentrations for polygonal active layer samples, snowmelt; ammonium concentrations for active layer samples; nitrate isotopes for active layer samples, snowmelt, permafrost; ammonium isotopes for active layer samples; and nitrogen isotopes for soils and dissolved organic nitrogen extracted from soil pore waters.

Indriect Measurement Of Nitrogen In A Mult-Component Natural Gas By Heating The Gas

DOEpatents

Morrow, Thomas B.; Behring, II, Kendricks A.

2004-06-22

Methods of indirectly measuring the nitrogen concentration in a natural gas by heating the gas. In two embodiments, the heating energy is correlated to the speed of sound in the gas, the diluent concentrations in the gas, and constant values, resulting in a model equation. Regression analysis is used to calculate the constant values, which can then be substituted into the model equation. If the diluent concentrations other than nitrogen (typically carbon dioxide) are known, the model equation can be solved for the nitrogen concentration.

Effects of the addition of different nitrogen sources in the tequila fermentation process at high sugar concentration.

PubMed

Arrizon, J; Gschaedler, A

2007-04-01

To study the effect of the addition of different nitrogen sources at high sugar concentration in the tequila fermentation process. Fermentations were performed at high sugar concentration (170 g l(-1)) using Agave tequilana Weber blue variety with and without added nitrogen from different sources (ammonium sulfate; glutamic acid; a mixture of ammonium sulfate and amino acids) during the exponential phase of growth. All the additions increased the fermentation rate and alcohol efficiency. The level of synthesis of volatile compounds depended on the source added. The concentration of amyl alcohols and isobutanol were decreased while propanol and acetaldehyde concentration increased. The most efficient nitrogen sources for fermentation rate were ammonium sulfate and the mixture of ammonium sulfate and amino acids. The level of volatile compounds produced depended upon types of nitrogen. The synthesis of some volatile compounds increased while others decreased with nitrogen addition. The addition of nitrogen could be a strategy for improving the fermentation rate and efficiency in the tequila fermentation process at high sugar Agave tequilana concentration. Furthermore, the sensory quality of the final product may change because the synthesis of the volatile compounds is modified.

Fate and effects of nitrogen and phosphorus in shallow vegetated aquatic ecosystems

USGS Publications Warehouse

Fairchild, James F.; Vradenburg, Leigh Ann

2006-01-01

Nitrate concentrations have greatly increased in streams and rivers draining agricultural regions of the Midwestern United States, increasing nitrate transport to the Gulf of Mexico has been implicated in the hypoxic conditions that threaten the productivity of marine fisheries. Increases in nitrate concentrations have been attributed to a combination of factors including agricultural expansion, increased nitrogen application rates, increased tile drainage, and loss of riparian Wetlands, These landscape-level changes have resulted in a decreased natural capacity for nitrogen uptake, removal, and cycling back to the atmosphere. Land managers are increasingly interested in using wetland construction and rehabilitation as a management practice to reduce loss of nitrate from the terrestrial systems. Yet, relatively little is known about the limnological factors involved in nitrate removal by Wetland systems.We conducted a series of studies from 1999-2000 to investigate the functional capacity of shallow, macrophyte-dominated pond wetland systems for uptake, assimilation, and retention of nitrogen (N) and phosphorus (P). We evaluated four factors that were hypothesized to influence nutrient uptake and assimilation: 1) nitrate loading rates; 2) nitrogen to phosphorus (N.P) ratios; 3) frequency of dosing/application; and 4) timing of dose initiation.Nutrient assimilation was rapid; store than 90% of added nutrients were removed from the water column in all treatments. Neither variation in N:P ratios (evaluated range, <13:1 to -114.1), frequency of application (weekly or bi-weekly), nor liming of dose initiation relative to macrophyte development (0%, 15-25%, or 75-90% maximum biomass) had significant effects on nutrient assimilation of wetland community dynamics. Maximum loading of nitrate (60 g N/m2 2.4 g P/m2) applied as six weekly doses stimulated algal communities, but inhibited macrophyte communities.Predicted shifts from a stable state of macrophyte- to phytoplankton-dominance did not occur due to nutrient additions. Macrophytes, phytoplankton, and the sediment surface were all significant factors in the removal of nitrate from the Water column. Overall, these shallow macrophyte-dominated systems provided an efficient means of removing nutrients from the water column. Construction or rehabilitation of shallow, vegetated wetlands may offer promise as land management practices for nutrient removal in agricultural watersheds.

Nitrogen removal from wastewater by an aerated subsurface-flow constructed wetland in cold climates.

PubMed

Redmond, Eric D; Just, Craig L; Parkin, Gene F

2014-04-01

The objective of this study was to assess the role of cyclic aeration, vegetation, and temperature on nitrogen removal by subsurface-flow engineered wetlands. Aeration was shown to enhance total nitrogen and ammonia removal and to enhance removal of carbonaceous biochemical oxygen demand, chemical oxygen demand, and phosphorus. Effluent ammonia and total nitrogen concentrations were significantly lower in aerated wetland cells when compared with unaerated cells. There was no significant difference in nitrogen removal between planted and unplanted cells. Effluent total nitrogen concentrations ranged from 9 to 12 mg N/L in the aerated cells and from 23 to 24 mg N/L in unaerated cells. Effluent ammonia concentrations ranged from 3 to 7 mg N/L in aerated wetland cells and from 22 to 23 mg N/L in unaerated cells. For the conditions tested, temperature had only a minimal effect on effluent ammonia or total nitrogen concentrations. The tanks-in-series and the PkC models predicted the general trends in effluent ammonia and total nitrogen concentrations, but did not do well predicting short-term variability. Rate coefficients for aerated systems were 2 to 10 times greater than those for unaerated systems.

[Transformation Regularity of Nitrogen in Aqueous Product Derived from Hydrothermal Liquefaction of Sewage Sludge in Subcritical Water].

PubMed

Sun, Yan-qing; Sun, Zhen; Zhang, Jing-lai

2015-06-01

Hydrothermal liquefaction in subcritical water is a potential way to treat sewage sludge as a resource rather than a waste. This study focused on the transformation regularity of nitrogen in aqueous product which was derived from hydrothermal liquefaction of sewage sludge under different operating conditions. Results showed, within the studied temperature scope and time span, the concentration of total nitrogen (TN) fluctuated in the range of 2867.62 mg x L(-1) to 4171.30 mg x L(-1). The two major exiting formation of nitrogen in aqueous product was ammonia nitrogen (NH4+ -N) and organic nitrogen (Org-N). NH4+ -N possessed 54.6%-90.7% of TN, while Org-N possessed 7.4%-44.5%. The concentration of nitrate nitrogen (NO- -N) was far more less than NH4+ -N and Org-N. Temperature had a great influence on the transformation regularity of nitrogen. Both the concentration of TN and Org-N increased accordingly to the increase of reaction temperature. With the reaction time prolonging, the concentration of TN and Org-N increased, while the concentration of NH4+ -N increased first, then became stationary, and then decreased slightly.

Tornadolike gravity-driven vortex model

NASA Technical Reports Server (NTRS)

Deissler, R. G.; Boldman, D. R.

1974-01-01

The buoyancy-induced vorticity concentration produced as the fluid in a vortex accelerates vertically was studied. The boiloff from liquid nitrogen, to which a small amount of initial vorticity was added, provided a source of cool, heavy gas in which a concentration of vorticity took place. Condensation streamers made the flow visible. It is shown that the presence of a surface boundary layer is not necessary for the effective concentration of vorticity. A simple theoretical analysis of the phenomenon was also made. A radial contraction of the flow with vertical position and a characteristic hook shape in the top view of the streamlines were observed in both theory and experiment. The vorticity concentration observed may be similar to that which occurs in tornadoes.

Glutamine nitrogen and ammonium nitrogen supplied as a nitrogen source is not converted into nitrate nitrogen of plant tissues of hydroponically grown pak-choi (Brassica chinensis L.).

PubMed

Wang, H-J; Wu, L-H; Tao, Q-N; Miller, D D; Welch, R M

2009-03-01

Many vegetables, especially leafy vegetables, accumulate NO(-) (3)-N in their edible portions. High nitrate levels in vegetables constitute a health hazard, such as cancers and blue baby syndrome. The aim of this study was to determine if (1) ammonium nitrogen (NH(+) (4)-N) and glutamine-nitrogen (Gln-N) absorbed by plant roots is converted into nitrate-nitrogen of pak-choi (Brassica chinensis L.) tissues, and (2) if nitrate-nitrogen (NO(-) (3)-N) accumulation and concentration of pak-choi tissues linearly increase with increasing NO(-) (3)-N supply when grown in nutrient solution. In experiment 1, 4 different nitrogen treatments (no nitrogen, NH(+) (4)-N, Gln-N, and NO(-) (3)-N) with equal total N concentrations in treatments with added N were applied under sterile nutrient medium culture conditions. In experiment 2, 5 concentrations of N (from 0 to 48 mM), supplied as NO(-) (3)-N in the nutrient solution, were tested. The results showed that Gln-N and NH(+) (4)-N added to the nutrient media were not converted into nitrate-nitrogen of plant tissues. Also, NO(-) (3)-N accumulation in the pak-choi tissues was the highest when plants were supplied 24 mM NO(-) (3)-N in the media. The NO(-) (3)-N concentration in plant tissues was quadratically correlated to the NO(-) (3)-N concentration supplied in the nutrient solution.

Spring thaw ionic pulses boost nutrient availability and microbial growth in entombed Antarctic Dry Valley cryoconite holes

PubMed Central

Telling, Jon; Anesio, Alexandre M.; Tranter, Martyn; Fountain, Andrew G.; Nylen, Thomas; Hawkings, Jon; Singh, Virendra B.; Kaur, Preeti; Musilova, Michaela; Wadham, Jemma L.

2014-01-01

The seasonal melting of ice entombed cryoconite holes on McMurdo Dry Valley glaciers provides oases for life in the harsh environmental conditions of the polar desert where surface air temperatures only occasionally exceed 0°C during the Austral summer. Here we follow temporal changes in cryoconite hole biogeochemistry on Canada Glacier from fully frozen conditions through the initial stages of spring thaw toward fully melted holes. The cryoconite holes had a mean isolation age from the glacial drainage system of 3.4 years, with an increasing mass of aqueous nutrients (dissolved organic carbon, total nitrogen, total phosphorus) with longer isolation age. During the initial melt there was a mean nine times enrichment in dissolved chloride relative to mean concentrations of the initial frozen holes indicative of an ionic pulse, with similar mean nine times enrichments in nitrite, ammonium, and dissolved organic matter. Nitrate was enriched twelve times and dissolved organic nitrogen six times, suggesting net nitrification, while lower enrichments for dissolved organic phosphorus and phosphate were consistent with net microbial phosphorus uptake. Rates of bacterial production were significantly elevated during the ionic pulse, likely due to the increased nutrient availability. There was no concomitant increase in photosynthesis rates, with a net depletion of dissolved inorganic carbon suggesting inorganic carbon limitation. Potential nitrogen fixation was detected in fully melted holes where it could be an important source of nitrogen to support microbial growth, but not during the ionic pulse where nitrogen availability was higher. This study demonstrates that ionic pulses significantly alter the timing and magnitude of microbial activity within entombed cryoconite holes, and adds credence to hypotheses that ionic enrichments during freeze-thaw can elevate rates of microbial growth and activity in other icy habitats, such as ice veins and subglacial regelation zones. PMID:25566210

Spring thaw ionic pulses boost nutrient availability and microbial growth in entombed Antarctic Dry Valley cryoconite holes.

PubMed

Telling, Jon; Anesio, Alexandre M; Tranter, Martyn; Fountain, Andrew G; Nylen, Thomas; Hawkings, Jon; Singh, Virendra B; Kaur, Preeti; Musilova, Michaela; Wadham, Jemma L

2014-01-01

The seasonal melting of ice entombed cryoconite holes on McMurdo Dry Valley glaciers provides oases for life in the harsh environmental conditions of the polar desert where surface air temperatures only occasionally exceed 0°C during the Austral summer. Here we follow temporal changes in cryoconite hole biogeochemistry on Canada Glacier from fully frozen conditions through the initial stages of spring thaw toward fully melted holes. The cryoconite holes had a mean isolation age from the glacial drainage system of 3.4 years, with an increasing mass of aqueous nutrients (dissolved organic carbon, total nitrogen, total phosphorus) with longer isolation age. During the initial melt there was a mean nine times enrichment in dissolved chloride relative to mean concentrations of the initial frozen holes indicative of an ionic pulse, with similar mean nine times enrichments in nitrite, ammonium, and dissolved organic matter. Nitrate was enriched twelve times and dissolved organic nitrogen six times, suggesting net nitrification, while lower enrichments for dissolved organic phosphorus and phosphate were consistent with net microbial phosphorus uptake. Rates of bacterial production were significantly elevated during the ionic pulse, likely due to the increased nutrient availability. There was no concomitant increase in photosynthesis rates, with a net depletion of dissolved inorganic carbon suggesting inorganic carbon limitation. Potential nitrogen fixation was detected in fully melted holes where it could be an important source of nitrogen to support microbial growth, but not during the ionic pulse where nitrogen availability was higher. This study demonstrates that ionic pulses significantly alter the timing and magnitude of microbial activity within entombed cryoconite holes, and adds credence to hypotheses that ionic enrichments during freeze-thaw can elevate rates of microbial growth and activity in other icy habitats, such as ice veins and subglacial regelation zones.

Fed-batch strategy for enhancing cell growth and C-phycocyanin production of Arthrospira (Spirulina) platensis under phototrophic cultivation.

PubMed

Xie, Youping; Jin, Yiwen; Zeng, Xianhai; Chen, Jianfeng; Lu, Yinghua; Jing, Keju

2015-03-01

The C-phycocyanin generated in blue-green algae Arthrospira platensis is gaining commercial interest due to its nutrition and healthcare value. In this study, the light intensity and initial biomass concentration were manipulated to improve cell growth and C-phycocyanin production of A.platensis in batch cultivation. The results show that low light intensity and high initial biomass concentration led to increased C-phycocyanin accumulation. The best C-phycocyanin productivity occurred when light intensity and initial biomass concentration were 300μmol/m(2)/s and 0.24g/L, respectively. The fed-batch cultivation proved to be an effective strategy to further enhance C-phycocyanin production of A.platensis. The results indicate that C-phycocyanin accumulation not only requires nitrogen-sufficient condition, but also needs other nutrients. The highest C-phycocyanin content (16.1%), production (1034mg/L) and productivity (94.8mg/L/d) were obtained when using fed-batch strategy with 5mM medium feeding. Copyright © 2014 Elsevier Ltd. All rights reserved.

Phytoplankton succession in an isolated upwelled Benguela water body in relation to different initial nutrient conditions

NASA Astrophysics Data System (ADS)

Wasmund, Norbert; Nausch, Günther; Hansen, Anja

2014-11-01

Freshly upwelled water is poor in phytoplankton biomass but rich in nutrients. With its ageing, phytoplankton biomass increases whereas the nutrients are consumed. The overall aim of our investigation was to check the succession in the phytoplankton composition as a consequence of changing nutrient conditions. The experiments were carried out in mesocosms filled with surface water in the northern Benguela region and installed on board of R/V "Maria S. Merian". In the freshly upwelled water, phytoplankton took up nitrogen at a higher rate than phosphorus if compared with the Redfield ratio. Therefore, nitrogen was exhausted already by day 6. Nitrogen limitation after day 6 was indicated by decreasing chlorophyll a (chla) concentrations, primary production rates and productivity indices and increasing C/N ratios in particulate matter. Despite nitrogen limitation, phosphorus addition stimulated further growth, mainly of diatoms, pointing to luxury uptake. Cyanobacteria did not develop and nitrogen fixation was zero even with phosphorus and iron addition. Diatoms stay the most important group in the freshly upwelled water, but autotrophic and heterotrophic dinoflagellates increase strongly in the matured upwelled water. Mesocosms excluded disturbances by advective water transports, which influence the study of succssions under field conditions.

Relations of biological indicators to nutrient data for lakes and streams in Pennsylvania and West Virginia, 1990-98

USGS Publications Warehouse

Brightbill, Robin A.; Koerkle, Edward H.

2003-01-01

The Clean Water Action Plan of 1998 provides a blueprint for federal agencies to work with states, tribes, and other stakeholders to protect and restore the Nation's water resources. The plan includes an initiative that addresses the nutrient-enrichment problem of lakes and streams across the United States. The U.S. Environmental Protection Agency (USEPA) is working to set nutrient criteria by nationwide nutrient ecoregions that are an aggregation of the Omernik level III ecoregions. Because low levels of nutrients are necessary for healthy streams and elevated concentrations can cause algal blooms that deplete available oxygen and kill off aquatic organisms, criteria levels are to be set, in part, using the relation between chlorophyll a and concentrations of total nitrogen and total phosphorus.Data from Pennsylvania and West Virginia, collected between 1990 and 1998, were analyzed for relations between chlorophyll a, nutrients, and other explanatory variables. Both phytoplankton and periphyton chlorophyll a concentrations from lakes and streams were analyzed separately within each of the USEPA nutrient ecoregions located within the boundaries of the two states. These four nutrient ecoregions are VII (Mostly Glaciated Dairy), VIII (Nutrient Poor, Largely Glaciated Upper Midwest and Northeast), IX (Southeastern Temperate Forested Plains and Hills), and XI (Central and Eastern Forested Uplands).Phytoplankton chlorophyll a concentrations in lakes were related to total nitrogen, total phosphorus, Secchi depth, concentration of dissolved oxygen, pH, water temperature, and specific conductivity. In nutrient ecoregion VII, nutrients were not significant predictors of chlorophyll a concentrations. Total nitrogen, Secchi depth, and pH were significantly related to phytoplankton chlorophyll a concentrations in nutrient ecoregion IX. Lake periphyton chlorophyll a concentrations from nutrient ecoregion XI were related to total phosphorus rather than total nitrogen, Secchi depth, and pH. In all cases, Secchi depth was inversely related to the chlorophyll a concentrations in a lake. Nutrient ecoregion VIII had too few samples for any type of analysis.Streams within the different nutrient ecoregions had many variables that were significantly related to periphyton chlorophyll a concentrations. These variables consisted of total nitrogen, total phosphorus, drainage area, percent forest cover, several macroinvertebrate indices, pH, basin slope, total residue, total suspended solids, and water temperature. Nutrients were not significantly related to periphyton chlorophyll a in streams within nutrient ecoregions VII or IX but were in nutrient ecoregion XI. Drainage area, percent forest cover, and several invertebrate indices were significant variables in nutrient ecoregion VII. Percent forest cover and several invertebrate indices had a negative relation with chlorophyll a concentrations in these streams. Percent forest cover and basin slope had a negative effect on periphyton in nutrient ecoregion IX streams. Light availability was more critical to periphyton growth in streams than nutrients.Ecoregion XI had enough samples to do seasonal analyses. Summer-season periphyton chlorophyll a concentrations in nutrient ecoregion XI streams were positively related to total phosphorus and drainage area but negatively related to percent forest cover. Summer-season phytoplankton in streams was related to different variables within the same nutrient ecoregion. Both total nitrogen and total phosphorus were positively related with chlorophyll a concentrations as well as basin slope, total residue, and total suspended solids but negatively related to pH. The winter stream phytoplankton chlorophyll a concentrations were related to water temperature only.

The Effect of Low Energy Nitrogen Ion Implantation on Graphene Nanosheets

NASA Astrophysics Data System (ADS)

Mishra, Mukesh; Alwarappan, Subbiah; Kanjilal, Dinakar; Mohanty, Tanuja

2018-03-01

Herein, we report the effect 50 keV nitrogen ion implantation at varying fluence on the optical properties of graphene nanosheets (number of layers < 5). Initially, graphene nanosheets synthesized by the direct liquid exfoliation of graphite layers were deposited on a cleaned Si-substrate by drop cast method. These graphene nanosheets are implanted with 50 keV nitrogen-ion beam at six different fluences. Raman spectroscopic results show that the D, D' and G peak get broadened up to the nitrogen ion fluence of 1 × 1015 ions/cm2, while 2D peak of graphene nanosheets disappeared for nitrogen-ions have fluence more than 1014 ions/cm2. However, further increase of fluence causes the indistinguishable superimposition of D, D' and G peaks. Surface contact potential value analysis for ion implanted graphene nanosheets shows the increase in defect concentration from 1.15 × 1012 to 1.98 × 1014 defects/cm2 with increasing the nitrogen ion fluence, which resembles the Fermi level shift towards conduction band. XRD spectra confirmed that the crystallinity of graphene nanosheets was found to tamper with increasing fluence. These results revealed that the limit of nitrogen ion implantation resistant on the vibrational behaviors for graphene nanosheets was 1015 ions/cm2 that opens up the scope of application of graphene nanosheets in device fabrication for ion-active environment and space applications.

Modeling the chemical evolution of nitrogen oxides near roadways

NASA Astrophysics Data System (ADS)

Wang, Yan Jason; DenBleyker, Allison; McDonald-Buller, Elena; Allen, David; Zhang, K. Max

2011-01-01

The chemical evolution of nitrogen dioxide (NO 2) and nitrogen monoxide (NO) in the vicinity of roadways is numerically investigated using a computational fluid dynamics model, CFD-VIT-RIT and a Gaussian-based model, CALINE4. CFD-VIT-RIT couples a standard k- ɛ turbulence model for turbulent mixing and the Finite-Rate model for chemical reactions. CALINE4 employs a discrete parcel method, assuming that chemical reactions are independent of the dilution process. The modeling results are compared to the field measurement data collected near two roadways in Austin, Texas, State Highway 71 (SH-71) and Farm to Market Road 973 (FM-973), under parallel and perpendicular wind conditions during the summer of 2007. In addition to ozone (O 3), other oxidants and reactive species including hydroperoxyl radical (HO 2), organic peroxyl radical (RO 2), formaldehyde (HCHO) and acetaldehyde (CH 3CHO) are considered in the transformation from NO to NO 2. CFD-VIT-RIT is shown to be capable of predicting both NO x and NO 2 profiles downwind. CALINE4 is able to capture the NO x profiles, but underpredicts NO 2 concentrations under high wind velocity. Our study suggests that the initial NO 2/NO x ratios have to be carefully selected based on traffic conditions in order to assess NO 2 concentrations near roadways. The commonly assumed NO 2/NO x ratio by volume of 5% may not be suitable for most roadways, especially those with a high fraction of heavy-duty truck traffic. In addition, high O 3 concentrations and high traffic volumes would lead to the peak NO 2 concentration occurring near roadways with elevated concentrations persistent over a long distance downwind.

The effect of surface movements on nitrogen mass transfer in liquid iron

NASA Astrophysics Data System (ADS)

Hirashima, N.; Choo, R. T. C.; Toguri, J. M.; Mukai, K.

1995-10-01

Marangoni convection due to surface tension gradients set up in a nitrogen-liquid iron system at 1873 K has been mathematically simulated and experimentally confirmed by measuring the rate of nitrogen absorption into liquid iron and by observing the free surface motion of liquid iron via zirconium oxide particles using X-ray radiography. This surface flow was created by blowing nitrogen gas through a small lance over the free surface of the liquid iron contained in an alumina boat under resistance heating. Absorption measurements indicated that the mass-transfer coefficient of nitrogen in liquid iron due to Marangoni convection ( k {m/1}>=1.5×10-4 m/s) is slightly less than that due to induction stirring ( k {m/1}=2.1×10-4 to 1.5×10-4 m/s). The free surface velocity induced by the surface tension gradient, with an initial composition difference of 425 to 10 ppm, was found to be of the order of 0.05 to 0.11 m/s. Mathematical modeling was also carried out to determine the velocity and nitrogen concentration profiles in the alumina boat. It was found that Marangoni convection creates mildly turbulent flows in liquid iron. Good agreements between the experimentally obtained data (nitrogen concentration and surface velocity) and the computed results were attained when a constant eddy viscosity which was five times the molecular value was assumed. This prescription allows both the predicted apparent mass-transfer coefficient and the predicted surface velocity to match the experimental results simultaneously. Note that the transport coefficients in the momentum and the convective-diffusive equations are correlated by the turbulent Schmidt number. The dimensionless mass-transfer correlation obtained for the present N-Fe system at 1873 K under resistance heating was found to be Sh=0.104 Re0.7·Sc0.7 with Sc=79.5 (3500

Modeling the transport of nitrogen in an NPP-2006 reactor circuit

NASA Astrophysics Data System (ADS)

Stepanov, O. E.; Galkin, I. Yu.; Sledkov, R. M.; Melekh, S. S.; Strebnev, N. A.

2016-07-01

Efficient radiation protection of the public and personnel requires detecting an accident-initiating event quickly. Specifically, if a heat-exchange tube in a steam generator is ruptured, the 16N radioactive nitrogen isotope, which contributes to a sharp increase in the steam activity before the turbine, may serve as the signaling component. This isotope is produced in the core coolant and is transported along the circulation circuit. The aim of the present study was to model the transport of 16N in the primary and the secondary circuits of a VVER-1000 reactor facility (RF) under nominal operation conditions. KORSAR/GP and RELAP5/Mod.3.2 codes were used to perform the calculations. Computational models incorporating the major components of the primary and the secondary circuits of an NPP-2006 RF were constructed. These computational models were subjected to cross-verification, and the calculation results were compared to the experimental data on the distribution of the void fraction over the steam generator height. The models were proven to be valid. It was found that the time of nitrogen transport from the core to the heat-exchange tube leak was no longer than 1 s under RF operation at a power level of 100% N nom with all primary circuit pumps activated. The time of nitrogen transport from the leak to the γ-radiation detection unit under the same operating conditions was no longer than 9 s, and the nitrogen concentration in steam was no less than 1.4% (by mass) of its concentration at the reactor outlet. These values were obtained using conservative approaches to estimating the leak flow and the transport time, but the radioactive decay of nitrogen was not taken into account. Further research concerned with the calculation of thermohydraulic processes should be focused on modeling the transport of nitrogen under RF operation with some primary circuit pumps deactivated.

Concentrations, fluxes, and yields of nitrogen, phosphorus, and suspended sediment in the Illinois River basin, 1996-2000

USGS Publications Warehouse

Terrio, Paul J.

2006-01-01

Concentrations, spatial and temporal variations, and fluxes of nitrogen, phosphorus, and suspended sediment were determined for 16 streams in the Illinois River Basin, Illinois from October 1996 through September 2000. Water samples were collected through the National Water-Quality Assessment's Lower Illinois River Basin (LIRB) and Upper Illinois River Basin (UIRB) Study Units on a monthly to weekly frequency from watersheds representing predominantly agricultural and urban land, as well as areas of mixed land-use. Streams in agricultural watersheds had high concentrations and fluxes of nitrate nitrogen, whereas streams in predominantly urban watersheds had high concentrations (above background levels) of ammonia nitrogen, organic nitrogen, and phosphorus. Median concentrations of nitrate nitrogen and total phosphorus were similar at the two Illinois River sampling stations (Illinois River at Ottawa, Ill. and Illinois River at Valley City, Ill.) that represented the downstream points of the UIRB and LIRB Study Units, respectively, and integrated multiple land-use areas. Concentrations of nitrogen were typically highest in the spring and lowest in the fall in agricultural watersheds, but highest in the winter in urban watersheds. Phosphorus concentrations in urban watersheds were highest in the fall and winter, but there was minimal seasonal variation in phosphorus concentrations in agricultural watersheds. Concentrations of nitrate and total nitrogen were affected primarily by non-point sources and hydrologic factors such as streamflow, storm intensity, watershed configuration, and soil permeability, whereas concentrations of phosphorus were affected largely by point-source contributions that typically have little seasonal variation. Seasonal variation in hydrologic conditions was an important factor for seasonal variation in nutrient concentration. Fluxes and yields of nitrogen and phosphorus forms varied substantially throughout the Illinois River Basin, and yields of specific nutrient forms were determined primarily by upstream land uses. Yields of nitrate nitrogen were highest in predominantly agricultural watersheds, whereas yields of phosphorus and ammonia nitrogen were highest in urban watersheds with wastewater effluent contributions. Yields of both total nitrogen and total phosphorus were similar at the two Illinois River stations representing the integrated UIRB and LIRB Study Units. Concentrations of suspended sediment ranged from 1 to 3,110 milligrams per liter (mg/L), with median concentrations generally higher in the UIRB. Suspended-sediment concentrations were highest and most variable in the LaMoine River Basin. The median concentration of suspended sediment in the Illinois River at Valley City, Ill. (155 mg/L) was twice as high as that at Ottawa, Ill. (80 mg/L). Fluxes of suspended sediment generally corresponded to watershed size and yields from agricultural watersheds were larger than yields from urban watersheds. The flux in the Illinois River at Valley City, Ill. (4,880,000 tons per year) was approximately four times the flux in the Illinois River at Ottawa, Ill. (1,060,000 tons per year).

In situ measurements of microbially-catalyzed nitrification and nitrate reduction rates in an ephemeral drainage channel receiving water from coalbed natural gas discharge, Powder River Basin, Wyoming, USA

USGS Publications Warehouse

Harris, S.H.; Smith, R.L.

2009-01-01

Nitrification and nitrate reduction were examined in an ephemeral drainage channel receiving discharge from coalbed natural gas (CBNG) production wells in the Powder River Basin, Wyoming. CBNG co-produced water typically contains dissolved inorganic nitrogen (DIN), primarily as ammonium. In this study, a substantial portion of discharged ammonium was oxidized within 50??m of downstream transport, but speciation was markedly influenced by diel fluctuations in dissolved oxygen (> 300????M). After 300??m of transport, 60% of the initial DIN load had been removed. The effect of benthic nitrogen-cycling processes on stream water chemistry was assessed at 2 locations within the stream channel using acrylic chambers to conduct short-term (2-6??h), in-stream incubations. The highest ambient DIN removal rates (2103????mol N m- 2 h- 1) were found at a location where ammonium concentrations > 350????M. This occurred during light incubations when oxygen concentrations were highest. Nitrification was occurring at the site, however, net accumulation of nitrate and nitrite accounted for < 12% of the ammonium consumed, indicating that other ammonium-consuming processes were also occurring. In dark incubations, nitrite and nitrate consumption were dominant processes, while ammonium was produced rather than consumed. At a downstream location nitrification was not a factor and changes in DIN removal rates were controlled by nitrate reduction, diel fluctuations in oxygen concentration, and availability of electron donor. This study indicates that short-term adaptation of stream channel processes can be effective for removing CBNG DIN loads given sufficient travel distances, but the long-term potential for nitrogen remobilization and nitrogen saturation remain to be determined.

Effect of Salinity and Alkalinity on Luciobarbus capito Gill Na+/K+-ATPase Enzyme Activity, Plasma Ion Concentration, and Osmotic Pressure

PubMed Central

2016-01-01

We evaluated the individual and combined effects of salinity and alkalinity on gill Na+/K+-ATPase enzyme activity, plasma ion concentration, and osmotic pressure in Luciobarbus capito. Increasing salinity concentrations (5, 8, 11, and 14 g/L) were associated with an initial increase and then decrease in L. capito gill Na+/K+-ATPase activity. Activity was affected by the difference between internal and external Na+ ion concentrations and osmotic pressure (P < 0.05). Both plasma ion (Na+, K+, and Cl−) concentration and osmotic pressure increased significantly (P < 0.05). An increase in alkalinity (15, 30, 45, and 60 mM) caused a significant increase in plasma K+ and urea nitrogen concentrations (P < 0.05) but had no effect on either plasma osmotic pressure or gill filament ATPase activity. In the two-factor experiment, the saline-alkaline interaction caused a significant increase in plasma ion (Na+, Cl−, and urea nitrogen) and osmotic pressure (P < 0.05). Variance analysis revealed that salinity, alkalinity, and their interaction significantly affected osmotic pressure, with salinity being most affected, followed by alkalinity, and their interaction. Gill filament ATPase activity increased at first and then decreased; peak values were observed in the orthogonal experiment group at a salinity of 8 g/L and alkalinity of 30 mM. PMID:27981049

Synergistic effects and optimization of nitrogen and phosphorus concentrations on the growth and nutrient uptake of a freshwater Chlorella vulgaris.

PubMed

Alketife, Ahmed M; Judd, Simon; Znad, Hussein

2017-01-01

The synergistic effects and optimization of nitrogen (N) and phosphorus (P) concentrations on the growth of Chlorella vulgaris (CCAP 211/11B, CS-42) and nutrient removal have been investigated under different concentrations of N (0-56 mg/L) and P (0-19 mg/L). The study showed that N/P ratio has a crucial effect on the biomass growth and nutrient removal. When N/P=10, a complete P and N removal was achieved at the end of cultivation with specific growth rate (SGR) of 1 d -1 and biomass concentration of 1.58 g/L. It was also observed that when the N content <2.5 mg/L, the SGR significantly reduced from 1.04 to 0.23 d -1 and the maximum biomass produced was decreased more than three-fold to 0.5 g/L. The Box-Behnken experimental design and response surface method were used to study the effects of the initial concentrations (P, N and C) on P and N removal efficiencies. The optimized P, N and C concentrations supporting 100% removal of both P and N at an SGR of 0.95 were 7, 55 and 10 mg/L respectively, with desirability value of 0.94. The results and analysis obtained could be very useful when applying the microalgae for efficient wastewater treatment and nutrient removal.

Depth profiling of nitrogen within 15N-incorporated nano-crystalline diamond thin films

NASA Astrophysics Data System (ADS)

Garratt, E.; AlFaify, S.; Cassidy, D. P.; Dissanayake, A.; Mancini, D. C.; Ghantasala, M. K.; Kayani, A.

2013-09-01

Nano-Crystalline Diamond (NCD) thin films are a topic of recent interest due to their excellent mechanical and electrical properties. The inclusion of nitrogen is a specific interest as its presence within NCD modifies its conductive properties. The methodology adopted for the characterization of nitrogen incorporated NCD films grown on a chromium underlayer determined a correlation between the chromium and nitrogen concentrations as well as a variation in the concentration profile of elements. Additionally, the concentration of nitrogen was found to be more than three times greater for these films versus those grown on a silicon substrate.

Measurement of Reactive Oxygen Species, Reactive Nitrogen Species, and Redox-Dependent Signaling in the Cardiovascular System: A Scientific Statement From the American Heart Association.

PubMed

Griendling, Kathy K; Touyz, Rhian M; Zweier, Jay L; Dikalov, Sergey; Chilian, William; Chen, Yeong-Renn; Harrison, David G; Bhatnagar, Aruni

2016-08-19

Reactive oxygen species and reactive nitrogen species are biological molecules that play important roles in cardiovascular physiology and contribute to disease initiation, progression, and severity. Because of their ephemeral nature and rapid reactivity, these species are difficult to measure directly with high accuracy and precision. In this statement, we review current methods for measuring these species and the secondary products they generate and suggest approaches for measuring redox status, oxidative stress, and the production of individual reactive oxygen and nitrogen species. We discuss the strengths and limitations of different methods and the relative specificity and suitability of these methods for measuring the concentrations of reactive oxygen and reactive nitrogen species in cells, tissues, and biological fluids. We provide specific guidelines, through expert opinion, for choosing reliable and reproducible assays for different experimental and clinical situations. These guidelines are intended to help investigators and clinical researchers avoid experimental error and ensure high-quality measurements of these important biological species. © 2016 American Heart Association, Inc.

Supercritical water oxidation of quinazoline: Reaction kinetics and modeling.

PubMed

Gong, Yanmeng; Guo, Yang; Wang, Shuzhong; Song, Wenhan; Xu, Donghai

2017-03-01

This paper presents a first quantitative kinetic model for supercritical water oxidation (SCWO) of quinazoline that describes the formation and interconversion of intermediates and final products at 673-873 K. The set of 11 reaction pathways for phenol, pyrimidine, naphthalene, NH 3 , etc, involved in the simplified reaction network proved sufficient for fitting the experimental results satisfactorily. We validated the model prediction ability on CO 2 yields at initial quinazoline loading not used in the parameter estimation. Reaction rate analysis and sensitivity analysis indicate that nearly all reactions reach their thermodynamic equilibrium within 300 s. The pyrimidine yielding from quinazoline is the dominant ring-opening pathway and provides a significant contribution to CO 2 formation. Low sensitivity of NH 3 decomposition rate to concentration confirms its refractory nature in SCWO. Nitrogen content in liquid products decreases whereas that in gaseous phase increases as reaction time prolonged. The nitrogen predicted by the model in gaseous phase combined with the experimental nitrogen in liquid products gives an accurate nitrogen balance of conversion process. Copyright © 2016 Elsevier Ltd. All rights reserved.

Kinetics of growth and lipids accumulation in Chlorella vulgaris during batch heterotrophic cultivation: Effect of different nutrient limitation strategies.

PubMed

Sakarika, Myrsini; Kornaros, Michael

2017-11-01

The present study aimed at: (1) determining the effect of sulfur addition on biomass growth and (2) assessing the effect of sulfur, phosphorus and nitrogen limitation on lipid accumulation by C. vulgaris SAG 211-11b. The sulfur cellular content was more than two-fold higher under nitrogen and phosphorus limitation (0.52% and 0.54%ww -1 , respectively) compared to sulfur requirements (0.20%ww -1 ) under sulfur limiting conditions. The nitrogen needs are significantly lower (2.81-3.35%ww -1 ) when compared to other microalgae and become 23% lower under nitrogen or phosphorus limitation. The microalga exhibited substrate inhibition above 30gL -1 initial glucose concentration. Sulfur limitation had the most significant effect on lipid accumulation, resulting in maximum total lipid content of 53.43±3.93%gg DW -1 . In addition to enhancing lipid productivity, adopting the optimal nutrient limitation strategy can result in cost savings by avoiding unnecessary nutrient additions and eliminate the environmental burden due to wasted resources. Copyright © 2017 Elsevier Ltd. All rights reserved.

Effects of culture conditions on growth and docosahexaenoic acid production from Schizochytrium limacinum

NASA Astrophysics Data System (ADS)

Zhu, Luying; Zhang, Xuecheng; Ren, Xueying; Zhu, Qinghua

2008-02-01

The effects of temperature, initial pH, salinity of culture medium, and carbon and nitrogen sources on growth and docosahexaenoic acid (C22: 6 n-3, DHA) production from Schizochytrium limacinum OUC88 were investigated in the present study. The results revealed that the optimal temperature, initial pH and salinity level of the medium for DHA production were 23°C, 7.0 and 18, respectively. Glucose was proved the best carbon source for the growth and DHA production from S. limacinum. Among the nitrogen sources tested, soybean cake hydrolysate, a cheap by-product, was found to be effective for the accumulation of DHA in S. limacinum cells. In addition, increasing the concentration of carbon sources in the medium caused a significant increase in cell biomass; however, accumulation of DHA in cells was mainly stimulated by the ratio of C/N in the medium. Under the optimal culture conditions, the maximum DHA yield achieved in flasks was 4.08 g L-1 after 5 d of cultivation.

Environmental modulation of microcystin and β-N-methylamino-L-alanine as a function of nitrogen availability.

PubMed

Scott, L L; Downing, S; Phelan, R R; Downing, T G

2014-09-01

The most significant modulators of the cyanotoxins microcystin and β-N-methylamino-L-alanine in laboratory cyanobacterial cultures are the concentration of growth-medium combined nitrogen and nitrogen uptake rate. The lack of field studies that support these observations led us to investigate the cellular content of these cyanotoxins in cyanobacterial bloom material isolated from a freshwater impoundment and to compare these to the combined nitrogen availability. We established that these toxins typically occur in an inverse relationship in nature and that their presence is mainly dependent on the environmental combined nitrogen concentration, with cellular microcystin present at exogenous combined nitrogen concentrations of 29 μM and higher and cellular BMAA correlating negatively with exogenous nitrogen at concentrations below 40 μM. Furthermore, opposing nutrient and light gradients that form in dense cyanobacterial blooms may result in both microcystin and BMAA being present at a single sampling site. Copyright © 2014 Elsevier Ltd. All rights reserved.

Biofiltration of air contaminated by styrene: Effect of nitrogen supply, gas flow rate, and inlet concentration

DOE Office of Scientific and Technical Information (OSTI.GOV)

Jorio, H.; Bibeau, L.; Heitz, M.

2000-05-01

The biofiltration process is a promising technology for the treatment of dilute styrene emissions in air. The efficiency of this process is however strongly dependent upon various operational parameters such as the filter bed characteristics, nutrient supplies, input contaminant concentrations, and gas flow rates. The biofiltration of air containing styrene vapors was therefore investigated, employing a novel biomass filter material, in two identical but separate laboratory scale biofiltration units (units 1 and 2), both biofilters being initially inoculated with a microbial consortium. Each biofilter was irrigated with a nutrient solution supplying nitrogen in one of two forms; i.e., mainly asmore » ammonia for unit 1 and exclusively as nitrate for unit 2. The experimental results have revealed that greater styrene elimination rates are achieved in the biofilter supplied with ammonia as the major nitrogen source in comparison to the lesser elimination performance obtained with the nitrate provided biofilter. However, in achieving the high styrene removal rates in the ammonia supplied biofilter, the excess of biomass accumulates on the filtering pellets and causes progressive clogging of the filter media. Furthermore, the effectiveness of nitrate supply as the sole nitrogen nutrient form, on reducing or controlling the biomass accumulation in the filter media in comparison to ammonia, could not be satisfactorily demonstrated because the two biofilters operated with very different styrene elimination capacities. The monitoring of the carbon dioxide concentration profile through both biofilters revealed that the ratio of carbon dioxide produced to the styrene removed was approximately 3/1, which confirms the complete biodegradation of removed styrene, given that some of the organic carbon consumed is also used for the microbial growth. The effects of the most important design parameters, namely styrene input concentrations and gas flow rates, were investigated for each nutrient solution.« less

Growth of Chlorella vulgaris and nutrient removal in the wastewater in response to intermittent carbon dioxide.

PubMed

Liu, Xiaoning; Ying, Kezhen; Chen, Guangyao; Zhou, Canwei; Zhang, Wen; Zhang, Xihui; Cai, Zhonghua; Holmes, Thomas; Tao, Yi

2017-11-01

In this study, Chlorella vulgaris (C. vulgaris) were cultured in cell culture flask supplied with intermittent CO 2 enriched gas. The impact of CO 2 concentration (from 1% to 20% v/v) on the growth of C. vulgaris cultured in domestic wastewater was exploited in various perspectives which include biomass, specific growth rate, culture pH, carbon consumption, and the removal of nitrogen and phosphorus compounds. The results showed that the maximum microalgal biomass concentration, 1.12 g L -1 , was achieved with 10% CO 2 as a feed gas. At 20% CO 2 the growth of C. vulgaris suffered from inhibition during initial 1.5 d, but acclimated to low pH (6.3 in average) with relatively higher specific growth rate (0.3-0.5 d -1 ) during subsequent culture period. After the rapid consumption of ammonium in the wastewater, an obvious decline in the nitrate concentration was observed, indicating that C. vulgaris prefer ammonium as a primary nitrogen source. The total nitrogen and phosphorus decreased from 44.0 mg L -1 to 2.1-5.4 mg L -1 and from 5.2 mg L -1 to 0-0.6 mg L -1 within 6.5 d under the aeration of 1-20% CO 2 , respectively, but no significant difference in consumed nitrogen versus phosphorus ratio was observed among different CO 2 concentration. The kinetics of nutrients removal were also determined through the application of pseudo first order kinetic model. 5-10% CO 2 aeration was optimal for the growth of C. vulgaris in the domestic wastewater, based on the coupling of carbon consumption, microalgal biomass, the nutrients removal and kinetics constants. Copyright © 2017 Elsevier Ltd. All rights reserved.

Modification of the G-phonon mode of graphene by nitrogen doping

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lukashev, Pavel V., E-mail: pavel.lukashev@uni.edu; Hurley, Noah; Zhao, Liuyan

2016-01-25

The effect of nitrogen doping on the phonon spectra of graphene is analyzed. In particular, we employ first-principles calculations and scanning Raman analysis to investigate the dependence of phonon frequencies in graphene on the concentration of nitrogen dopants. We demonstrate that the G phonon frequency shows oscillatory behavior as a function of nitrogen concentration. We analyze different mechanisms which could potentially be responsible for this behavior, such as Friedel charge oscillations around the localized nitrogen impurity atom, the bond length change between nitrogen impurity and its nearest neighbor carbon atoms, and the long-range interactions of the nitrogen point defects. Wemore » show that the bond length change and the long range interaction of point defects are possible mechanisms responsible for the oscillatory behavior of the G frequency as a function of nitrogen concentration. At the same time, Friedel charge oscillations are unlikely to contribute to this behavior.« less

Foliage plants for indoor removal of the primary combustion gases carbon monoxide and nitrogen dioxide

NASA Technical Reports Server (NTRS)

Wolverton, B. C.; Mcdonald, R. C.; Mesick, H. H.

1985-01-01

Foliage plants were evaluated for their ability to sorb carbon monoxide and nitrogen dioxide, the two primary gases produced during the combustion of fossil fuels and tobacco. The spider plant (Chlorophytum elatum var. vittatum) could sorb 2.86 micrograms CO/sq cm leaf surface in a 6 h photoperiod. The golden pothos (Scindapsus aureus) sorbed 0.98 micrograms CO/sq cm leaf surface in the same time period. In a system with the spider plant, greater than or equal to 99 percent of an initial concentration of 47 ppm NO2 could be removed in 6 h from a void volume of approximately 0.35 cu m. One spider plant potted in a 3.8 liter container can sorb 3300 micrograms CO and effect the removal of 8500 micrograms NO2/hour, recognizing the fact that a significant fraction of NO2 at high concentrations will be lost by surface sorption, dissolving in moisture, etc.

Fractionation of Nitrogen Isotopes by Plants with Different Types of Mycorrhiza in Mountain Tundra Ecosystems

NASA Astrophysics Data System (ADS)

Buzin, Igor; Makarov, Mikhail; Maslov, Mikhail; Tiunov, Alexei

2017-04-01

We studied nitrogen concentration and nitrogen isotope composition in plants from four mountain tundra ecosystems in the Khibiny Mountains. The ecosystems consisted of a toposequence beginning with the shrub-lichen heath (SLH) on the ridge and upper slope, followed by the Betula nana dominated shrub heath (SH) on the middle slope, the cereal meadow (CM) on the lower slope and the sedge meadow (SM) at the bottom of the slope. The inorganic nitrogen concentration of the soils from the studied ecosystems were significantly different; the SLH soil was found to contain the minimum concentration of N-NH4+ and N-NO3- , while in the soils of the meadow ecosystems these concentrations were much higher. The concentration of nitrogen in leaves of the dominant plant species in all of the ecosystems is directly connected with the concentration of inorganic nitrogen in the soils, regardless of the plant's mycorrhizal symbiosis type. However, such a correlation is not apparent in the case of plant roots, especially for plant roots with ectomycorrhiza and ericoid mycorrhiza. The majority of plant species with these types of mycorrhiza in the SH and particularly in the CM were enriched in 15N in comparison with the SLH (such plants were not found within the SM). This could be due to several reasons: 1) the decreasing role of mycorrhiza in nitrogen consumption and therefore in the fractionation of isotopes in the relatively-N-enriched ecosystems; 2) the use of relatively-15N-enriched forms of nitrogen for plant nutrition in meadow ecosystems. This heavier nitrogen isotope composition in plant roots with ectomycorrhiza and ericoid mycorrhiza in ecosystems with available nitrogen enriched soils doesn't correspond to the classical idea of mycorrhiza decreasing participation in nitrogen plant nutrition. The analysis of the isotope composition of separate labile forms of nitrogen makes it possible to explain the phenomenon. Not all arbuscular mycorrhizal species within the sedge meadow were 15N-enriched in comparison with other ecosystems. This could either be explained by the different role of mycorrhiza in nitrogen plant nutrition of different arbuscular mycorrhizal plant species or by the primary usage of various nitrogen compounds with different levels of 15N concentration in individual plant species. Acknowledgement: This study was supported by the Russian Foundation for Basic Research (16-04-00544).

Small-scale experimental study of vaporization flux of liquid nitrogen released on water.

PubMed

Gopalaswami, Nirupama; Olewski, Tomasz; Véchot, Luc N; Mannan, M Sam

2015-10-30

A small-scale experimental study was conducted using liquid nitrogen to investigate the convective heat transfer behavior of cryogenic liquids released on water. The experiment was performed by spilling five different amounts of liquid nitrogen at different release rates and initial water temperatures. The vaporization mass fluxes of liquid nitrogen were determined directly from the mass loss measured during the experiment. A variation of initial vaporization fluxes and a subsequent shift in heat transfer mechanism were observed with changes in initial water temperature. The initial vaporization fluxes were directly dependent on the liquid nitrogen spill rate. The heat flux from water to liquid nitrogen determined from experimental data was validated with two theoretical correlations for convective boiling. It was also observed from validation with correlations that liquid nitrogen was found to be predominantly in the film boiling regime. The substantial results provide a suitable procedure for predicting the heat flux from water to cryogenic liquids that is required for source term modeling. Copyright © 2015 Elsevier B.V. All rights reserved.

Nutrient concentrations in surface water and groundwater, and nitrate source identification using stable isotope analysis, in the Barnegat Bay-Little Egg Harbor watershed, New Jersey, 2010–11

USGS Publications Warehouse

Wieben, Christine M.; Baker, Ronald J.; Nicholson, Robert S.

2013-01-01

Five streams in the Barnegat Bay-Little Egg Harbor (BB-LEH) watershed in southern New Jersey were sampled for nutrient concentrations and stable isotope composition under base-flow and stormflow conditions, and during the growing and nongrowing seasons, to help quantify and identify sources of nutrient loading. Samples were analyzed for concentrations of total nitrogen, ammonia, nitrate plus nitrite, organic nitrogen, total phosphorus, and orthophosphate, and for nitrogen and oxygen stable isotope ratios. Concentrations of total nitrogen in the five streams appear to be related to land use, such that streams in subbasins characterized by extensive urban development (and historical agricultural land use)—North Branch Metedeconk and Toms Rivers—exhibited the highest total nitrogen concentrations (0.84–1.36 milligrams per liter (mg/L) in base flow). Base-flow total nitrogen concentrations in these two streams were dominated by nitrate; nitrate concentrations decreased during storm events as a result of dilution by storm runoff. The two streams in subbasins with the least development—Cedar Creek and Westecunk Creek—exhibited the lowest total nitrogen concentrations (0.16–0.26 mg/L in base flow), with organic nitrogen as the dominant species in both base flow and stormflow. A large proportion of these subbasins lies within forested parts of the Pinelands Area, indicating the likelihood of natural inputs of organic nitrogen to the streams that increase during periods of storm runoff. Base-flow total nitrogen concentrations in Mill Creek, in a moderately developed basin, were 0.43 to 0.62 mg/L and were dominated by ammonia, likely associated with leachate from a landfill located upstream. Total phosphorus and orthophosphate were not found at detectable concentrations in most of the surface-water samples, with the exception of samples collected from the North Branch Metedeconk River, where concentrations ranged from 0.02 to 0.09 mg/L for total phosphorus and 0.008 to 0.011 mg/L for orthophosphate. Measurements of nitrogen and oxygen stable isotope ratios of nitrate in surface-water samples revealed that a mixture of multiple subsurface sources, which may include some combination of animal and septic waste, soil nitrogen, and commercial fertilizers, likely contribute to the base-flow nitrogen load. The results also indicate that atmospheric deposition is not a predominant source of nitrogen transported to the BB-LEH estuary from the watershed, although the contribution of nitrate from the atmosphere increases during stormflow. Atmospheric deposition of nitrate has a greater influence in the less developed subbasins within the BB-LEH watershed, likely because few other major sources of nitrogen (animal and septic waste, fertilizers) are present in the less developed subbasins. Atmospheric sources appear to contribute proportionally less of the overall nitrate as development increases within the BB-LEH watershed. Groundwater samples collected from five wells located within the BB-LEH watershed and screened in the unconfined Kirkwood-Cohansey aquifer system were analyzed for nutrient and stable isotope composition. Concentrations of nitrate ranged from not detected to 3.63 mg/L, with the higher concentrations occurring in the highly developed northern portion of the watershed, indicating the likelihood of anthropogenic sources of nitrogen. Isotope data for the two wells with the highest nitrate concentrations are more consistent with fertilizer sources than with animal or septic waste. Total phosphorus was not detected in any of the wells sampled, and orthophosphate was either not detected or measured at very low concentrations (0.005–0.009 mg/L) in each of the wells sampled.

Leaf reflectance-nitrogen-chlorophyll relations among three south Texas woody rangeland plant species

NASA Technical Reports Server (NTRS)

Gausman, H. W.; Everitt, J. H.; Escobar, D. E. (Principal Investigator)

1982-01-01

Annual variations in the nitrogen-chlorophyll leaf reflectance of hackberry, honey mesquite and live oak in south Texas, were compared. In spring, leaf reflectance at the 0.55 m wavelength and nitrogen (N) concentration was high but leaf chlorophyll (chl) concentrations were low. In summer, leaf reflectance and N-concentration were low but lead chl concentrations were high. Linear correlations for both spring and summer of leaf reflectance with N and chl concentration or deviations from linear regression were not statistically significant.

Dynamics of nitrogen in subtropical wetland and its uptake and storage by Pistia stratiotes.

PubMed

Irfan, Sufia; Shardendu

2009-11-01

The paper describes the dynamics of nitrogen in different components (water, soil and plants) of Kabar wetland situated in Begusarai district of Bihar. Contents of nitrogen in the natural components were determined and were compared with the rate of uptake and accumulation under the experimental conditions. Physico-chemical characteristics of natural water and of test basins were quite similar. The trend of seasonal variation of NO3(-)-N in water and total N in soil and P. stratiotes tissue was almost similar but content of nitrogen differed significantly in the different components. The accumulation of nitrogen in the tissues of P. stratiotes was 5 to 15 fold higher than the concentration of nitrogen in the water and 2 to 3 fold higher than the nitrogen content measured in the soil. Maximum accumulation of nitrogen in P. stratiotes was 15.25 mg g(-1) when the concentration of NO3(-)-N in water was 0.86 mg l(-1). Under experimental conditions six different nitrogen concentrations were supplied and determined the uptake and accumulation of nitrogen in P. stratiotes. Maximum uptake and accumulation was 82.87 g m(-2) at the end of 60 days after starting the experiment but still the rate of accumulation was in rising trend. In another part of experiment no nitrogen was left in the basins of low concentrations (0.5 and 5 mg N l(-1)) at the end of 60 days of experiment but at higher concentrations (50 and 65 mg N l(-1)) significant amount of N was left in the test basin. The biomass enhancement was parallel with nitrogen supply till 15 mg N l(-1). This was opposite to the relationship between the nitrogen accumulation in the tissues and nitrogen supply in the experimental basins. Though, potassium was added as an essential growth nutrient but its accumulation was 95g m(-2) at 5 mg l(-1).

The microbial nitrogen cycling potential is impacted by polyaromatic hydrocarbon pollution of marine sediments

DOE PAGES

Scott, Nicole M.; Hess, Matthias; Bouskill, Nick J.; ...

2014-03-25

During hydrocarbon exposure, the composition and functional dynamics of marine microbial communities are altered, favoring bacteria that can utilize this rich carbon source. Initial exposure of high levels of hydrocarbons in aerobic surface sediments can enrich growth of heterotrophic microorganisms having hydrocarbon degradation capacity. As a result, there can be a localized reduction in oxygen potential within the surface layer of marine sediments causing anaerobic zones. We hypothesized that increasing exposure to elevated hydrocarbon concentrations would positively correlate with an increase in denitrification processes and the net accumulation of dinitrogen. This hypothesis was tested by comparing the relative abundance ofmore » genes associated with nitrogen metabolism and nitrogen cycling identified in 6 metagenomes from sediments contaminated by polyaromatic hydrocarbons from the Deepwater Horizon (DWH) oil spill in the Gulf of Mexico, and 3 metagenomes from sediments associated with natural oil seeps in the Santa Barbara Channel. An additional 8 metagenomes from uncontaminated sediments from the Gulf of Mexico were analyzed for comparison. We predicted relative changes in metabolite turnover as a function of the differential microbial gene abundances, which showed predicted accumulation of metabolites associated with denitrification processes, including anammox, in the contaminated samples compared to uncontaminated sediments, with the magnitude of this change being positively correlated to the hydrocarbon concentration and exposure duration. Furthermore, these data highlight the potential impact of hydrocarbon inputs on N cycling processes in marine sediments and provide information relevant for system scale models of nitrogen metabolism in affected ecosystems.« less

The microbial nitrogen cycling potential is impacted by polyaromatic hydrocarbon pollution of marine sediments

DOE Office of Scientific and Technical Information (OSTI.GOV)

Scott, Nicole M.; Hess, Matthias; Bouskill, Nick J.

2014-03-25

During hydrocarbon exposure, the composition and functional dynamics of marine microbial communities are altered, favoring bacteria that can utilize this rich carbon source. Initial exposure of high levels of hydrocarbons in aerobic surface sediments can enrich growth of heterotrophic microorganisms having hydrocarbon degradation capacity. As a result, there can be a localized reduction in oxygen potential within the surface layer of marine sediments causing anaerobic zones. We hypothesized that increasing exposure to elevated hydrocarbon concentrations would positively correlate with an increase in denitrification processes and the net accumulation of dinitrogen. This hypothesis was tested by comparing the relative abundance ofmore » genes associated with nitrogen metabolism and nitrogen cycling identified in 6 metagenomes from sediments contaminated by polyaromatic hydrocarbons from the Deepwater Horizon (DWH) oil spill in the Gulf of Mexico, and 3 metagenomes from sediments associated with natural oil seeps in the Santa Barbara Channel. An additional 8 metagenomes from uncontaminated sediments from the Gulf of Mexico were analyzed for comparison. We predicted relative changes in metabolite turnover as a function of the differential microbial gene abundances, which showed predicted accumulation of metabolites associated with denitrification processes, including anammox, in the contaminated samples compared to uncontaminated sediments, with the magnitude of this change being positively correlated to the hydrocarbon concentration and exposure duration. These data highlight the potential impact of hydrocarbon inputs on N cycling processes in marine sediments and provide information relevant for system scale models of nitrogen metabolism in affected ecosystems« less

Interactions of tissue and fertilizer nitrogen on decomposition dynamics of lignin-rich conifer litter

USGS Publications Warehouse

Perakis, Steven S.; Matkins, Joselin J.; Hibbs, David E.

2012-01-01

High tissue nitrogen (N) accelerates decomposition of high-quality leaf litter in the early phases of mass loss, but the influence of initial tissue N variation on the decomposition of lignin-rich litter is less resolved. Because environmental changes such as atmospheric N deposition and elevated CO2 can alter tissue N levels within species more rapidly than they alter the species composition of ecosystems, it is important to consider how within-species variation in tissue N may shape litter decomposition and associated N dynamics. Douglas-fir (Pseudotsuga menziesii ) is a widespread lignin-rich conifer that dominates forests of high carbon (C) storage across western North America, and displays wide variation in tissue and litter N that reflects landscape variation in soil N. We collected eight unique Douglas-fir litter sources that spanned a two-fold range in initial N concentrations (0.67–1.31%) with a narrow range of lignin (29–35%), and examined relationships between initial litter chemistry, decomposition, and N dynamics in both ambient and N fertilized plots at four sites over 3 yr. High initial litter N slowed decomposition rates in both early (0.67 yr) and late (3 yr) stages in unfertilized plots. Applications of N fertilizer to litters accelerated early-stage decomposition, but slowed late-stage decomposition, and most strongly affected low-N litters, which equalized decomposition rates across litters regardless of initial N concentrations. Decomposition of N-fertilized litters correlated positively with initial litter manganese (Mn) concentrations, with litter Mn variation reflecting faster turnover of canopy foliage in high N sites, producing younger litterfall with high N and low Mn. Although both internal and external N inhibited decomposition at 3 yr, most litters exhibited net N immobilization, with strongest immobilization in low-N litter and in N-fertilized plots. Our observation for lignin-rich litter that high initial N can slow decomposition yet accelerate N release differs from findings where litter quality variation across species promotes coupled C and N release during decomposition. We suggest reevaluation of ecosystem models and projected global change effects to account for a potential decoupling of ecosystem C and N feedbacks through litter decomposition in lignin-rich conifer forests.

A mesocosm study using four native Hawaiian plants to assess nitrogen accumulation under varying surface water nitrogen concentrations.

PubMed

Unser, C U; Bruland, G L; Hood, A; Duin, K

2010-01-01

Accumulation of nitrogen (N) by native Hawaiian riparian plants from surface water was measured under a controlled experimental mesocosm setting. Four species, Cladium jamaicense, Cyperus javanicus, Cyperus laevigatus, and Cyperus polystachyos were tested for their ability to survive in coconut fiber coir log media with exposure to differing N concentrations. It was hypothesized that the selected species would have significantly different tissue total nitrogen (TN) concentrations, aboveground biomass, and TN accumulation rates because of habitat preference and physiological growth differences. A general linear model (GLM) analysis of variance (ANOVA) determined that species differences accounted for the greatest proportion of variance in tissue TN concentration, aboveground biomass growth, and accumulation rates, when compared with the other main effects (i.e. N concentration, time) and their interactions. A post hoc test of means demonstrated that C. jamaicense had significantly higher tissue TN concentration, aboveground biomass growth, and accumulation rates than the other species under all N concentrations. It was also hypothesized that tissue TN concentrations and biomass growth would increase in plants exposed to elevated N concentrations, however data did not support this hypothesis. Nitrogen accumulation rates by species were controlled by differences in plant biomass growth.

Nitrogen-Induced Perturbation of the Valence Band States in GaP1-xNx Alloys

DOE Office of Scientific and Technical Information (OSTI.GOV)

Dudiy, S. V.; Zunger, A.; Felici, M.

2006-01-01

The effects of diluted nitrogen impurities on the valence- and conduction-band states of GaP{sub 1-x}N{sub x} have been predicted and measured experimentally. The calculation uses state-of-the-art atomistic modeling: we use large supercells with screened pseudopotentials and consider several random realizations of the nitrogen configurations. These calculations agree with photoluminescence excitation (PLE) measurements performed for nitrogen concentrations x up to 0.035 and photon energies up to 1 eV above the GaP optical-absorption edge, as well as with published ellipsometry data. In particular, a predicted nitrogen-induced buildup of the L character near the valence- and conduction-band edges accounts for the surprising broad-absorptionmore » plateau observed in PLE between the X{sub 1c} and the {Lambda}{sub 1c} critical points of GaP. Moreover, theory accounts quantitatively for the downward bowing of the indirect conduction-band edge and for the upward bowing of the direct transition with increasing nitrogen concentration. We review some of the controversies in the literature regarding the shifts in the conduction band with composition, and conclude that measured results at ultralow N concentration cannot be used to judge behavior at a higher concentration. In particular, we find that at the high concentrations of nitrogen studied here ({approx}1%) the conduction-band edge (CBE) is a hybridized state made from the original GaP X{sub 1c} band-edge state plus all cluster states. In this limit, the CBE plunges down in energy as the N concentration increases, in quantitative agreement with the measurements reported here. However, at ultralow nitrogen concentrations (<0.1%), the CBE is the nearly unperturbed host X{sub 1c}, which does not sense the nitrogen cluster levels. Thus, this state does not move energetically as nitrogen is added and stays pinned in energy, in agreement with experimental results.« less

[Influence of elevated atmospheric CO2 concentration on photosynthesis and leaf nitrogen partition in process of photosynthetic carbon cycle in Musa paradisiaca].

PubMed

Sun, G; Zhao, P; Zeng, X; Peng, S

2001-06-01

The photosynthetic rate (Pn) in leaves of Musa paradisiaca grown under elevated CO2 concentration (700 +/- 56 microliters.L-1) for one week was 5.14 +/- 0.32 mumol.m-2.s-1, 22.1% higher than that under ambient CO2 concentration, while under elevated CO2 concentration for 8 week, the Pn decreased by 18.1%. It can be inferred that the photosynthetic acclimation to elevated CO2 concentration and the Pn inhibition occurred in leaves of M. paradisiaca. The respiration rate in light (Rd) was lower in leaves under higher CO2 concentration, compared with that under ambient CO2 concentration. If the respiration in light was not included, the difference in CO2 compensation point for the leaves of both plants was not significant. Under higher CO2 concentration for 8 weeks, the maximum carboxylation rate(Vcmax) and electron transportation rate (J) in leaves decreased respectively by 30.5% and 14.8%, compared with that under ambient CO2 concentration. The calculated apparent quantum yield (alpha) in leaves under elevated CO2 concentration according to the initial slope of Pn/PAR was reduced to 0.014 +/- 0.010 molCO2.mol-1 quanta, compared with the value of 0.025 +/- 0.005 molCO2.mol-1 quanta in the control. The efficiency of light energy conversion also decreased from 0.203 to 0.136 electrons.quanta-1 in plants under elevated CO2 concentration. A lower partitioning coefficient for leaf nitrogen in Rubisco, bioenergetics and thylakoid light-harvesting components was observed in plants under higher CO2 concentration. The results indicated that the multi-process of photosynthesis was suppressed significantly by a long-term (8 weeks) higher CO2 concentration incubation.

Nitrogen composition in urban runoff--implications for stormwater management.

PubMed

Taylor, Geoff D; Fletcher, Tim D; Wong, Tony H F; Breen, Peter F; Duncan, Hugh P

2005-05-01

A study was conducted to characterise the composition of nitrogen in urban stormwater in Melbourne, Australia, during baseflows and storm events, and to compare the results with international data. Nitrogen in Melbourne stormwater was predominantly dissolved (approximately 80%), with ammonia the least-abundant form (approximately 11%). Concentrations of nitrogen species did not vary significantly between baseflow and storms, although the proportion of nitrogen in particulate form was higher during storm events (p = 0.04). Whilst the composition of nitrogen in Melbourne was broadly consistent with international data, the level of dissolved inorganic nitrogen was higher in Melbourne (mu = 48% during baseflows and 49% during storms) than in the international literature (mu = 29%). Limitations in the international dataset precluded comparison of total dissolved nitrogen. The results have implications for stormwater management. Whilst nitrogen species concentrations are variable, they are not strongly related to flow conditions, so treatment systems must be designed to cope with stochastic inflow concentrations at all times. To optimise their performance, stormwater treatments should be designed to improve dissolved nitrogen removal. Further research is needed to improve the ability of treatment systems to achieve this aim.

The impact of changes in source water quality on trihalomethane and haloacetonitrile formation in chlorinated drinking water.

PubMed

Xue, Chonghua; Wang, Qi; Chu, Wenhai; Templeton, Michael R

2014-12-01

This study examined the formation of disinfection by-products (DBPs), including nitrogenous DBPs, haloacetonitriles (HANs), and carbonaceous DBPs, trihalomethanes (THMs), upon chlorination of water samples collected from a conventional Chinese surface water treatment plant (i.e. applying coagulation, sedimentation, and filtration). Reductions in the average concentrations (and range, shown in brackets) of dissolved organic carbon (DOC) and dissolved organic nitrogen (DON) from 4.8 (3.0-7.3) μg/L and 0.52 (0.20-0.81) μg/L in 2010 to 2.4 (1.4-3.7) μg/L and 0.17 (0.11-0.31) μg/L in 2012, respectively, led to a decrease in HANs and THMs from 5.3 and 28.5 μg/L initially to 0.85 and 8.2 μg/L, as average concentrations, respectively. The bromide concentration in the source water also decreased from 2010 to 2012, but the bromine incorporation factor (BIF) for the THMs did not change significantly; however, for HAN the BIFs increased because the reduction in DON was higher than that of bromide. There was good linear relationship between DOC and THM concentrations, but not between DON and HANs. Copyright © 2014 Elsevier Ltd. All rights reserved.

Aerobic cyanide degradation by bacterial isolates from cassava factory wastewater

PubMed Central

Kandasamy, Sujatha; Dananjeyan, Balachandar; Krishnamurthy, Kumar; Benckiser, Gero

2015-01-01

Ten bacterial strains that utilize cyanide (CN) as a nitrogen source were isolated from cassava factory wastewater after enrichment in a liquid media containing sodium cyanide (1 mM) and glucose (0.2% w/v). The strains could tolerate and grow in cyanide concentrations of up to 5 mM. Increased cyanide levels in the media caused an extension of lag phase in the bacterial growth indicating that they need some period of acclimatisation. The rate of cyanide removal by the strains depends on the initial cyanide and glucose concentrations. When initial cyanide and glucose concentrations were increased up to 5 mM, cyanide removal rate increased up to 63 and 61 per cent by Bacillus pumilus and Pseudomonas putida. Metabolic products such as ammonia and formate were detected in culture supernatants, suggesting a direct hydrolytic pathway without an intermediate formamide. The study clearly demonstrates the potential of aerobic treatment with cyanide degrading bacteria for cyanide removal in cassava factory wastewaters. PMID:26413045

Aerobic cyanide degradation by bacterial isolates from cassava factory wastewater.

PubMed

Kandasamy, Sujatha; Dananjeyan, Balachandar; Krishnamurthy, Kumar; Benckiser, Gero

2015-01-01

Ten bacterial strains that utilize cyanide (CN) as a nitrogen source were isolated from cassava factory wastewater after enrichment in a liquid media containing sodium cyanide (1 mM) and glucose (0.2% w/v). The strains could tolerate and grow in cyanide concentrations of up to 5 mM. Increased cyanide levels in the media caused an extension of lag phase in the bacterial growth indicating that they need some period of acclimatisation. The rate of cyanide removal by the strains depends on the initial cyanide and glucose concentrations. When initial cyanide and glucose concentrations were increased up to 5 mM, cyanide removal rate increased up to 63 and 61 per cent by Bacillus pumilus and Pseudomonas putida. Metabolic products such as ammonia and formate were detected in culture supernatants, suggesting a direct hydrolytic pathway without an intermediate formamide. The study clearly demonstrates the potential of aerobic treatment with cyanide degrading bacteria for cyanide removal in cassava factory wastewaters.

Effect of ammonium and amino acids on the growth of selected strains of Gluconobacter and Acetobacter.

PubMed

Sainz, F; Mas, A; Torija, M J

2017-02-02

Acetic acid bacteria (AAB) are a group of microorganisms highly used in the food industry. However, its use can be limited by the insufficient information known about the nutritional requirements of AAB for optimal growth. The aim of this work was to study the effects of different concentrations and sources of nitrogen on the growth of selected AAB strains and to establish which nitrogen source best encouraged their growth. Two strains of three species of AAB, Gluconobacter japonicus, Gluconobacter oxydans and Acetobacter malorum, were grown in three different media with diverse nitrogen concentrations (25, 50, 100, and 300mgN/L and 1gN/L) as a complete solution of amino acids and ammonium. With this experiment, the most favourable medium and the lowest nitrogen concentration beneficial for the growth of each strain was selected. Subsequently, under these conditions, single amino acids or ammonium were added to media individually to determine the best nitrogen sources for each AAB strain. The results showed that nitrogen requirements are highly dependent on the nitrogen source, the medium and the AAB strain. Gluconobacter strains were able to grow in the lowest nitrogen concentration tested (25mgN/L); however, one of the G. oxydans strains and both A. malorum strains required a higher concentration of nitrogen (100-300mgN/L) for optimal growth. In general, single nitrogen sources were not able to support the growth of these AAB strains as well as the complete solution of amino acids and ammonium. Copyright © 2016 Elsevier B.V. All rights reserved.

Use of the USEPA Estuary Nitrogen Model to Estimate Concentrations of Total Nitrogen in Estuaries Using Loads Calculated by Watershed Models and Monitoring Data

EPA Science Inventory

We use USEPA’s Estuary Nitrogen Model (ENM) to calculate annual average concentrations of total nitrogen (TN) in ten estuaries or sub-estuaries along the Atlantic coast from New Hampshire to Florida. These include a variety of systems, ranging from strongly-flushed bays to weakly...

Distribution of Argon Arc Contaminated with Nitrogen as Function of Frequency in Pulsed TIG Welding

NASA Astrophysics Data System (ADS)

Takahashi, Hiroki; Tanaka, Tatsuro; Yamamoto, Shinji; Iwao, Toru

2016-09-01

TIG arc welding is the high-quality and much applicable material joining technology. However, the current has to be small because the cathode melting should be prevented. In this case, the heat input to the welding pool becomes low, then, the welding defect sometimes occurs. The pulsed TIG arc welding is used to improve this disadvantage This welding can be controlled by some current parameters such as frequency However, few report has reported the distribution of argon arc contaminated with nitrogen It is important to prevent the contamination of nitrogen because the melting depth increases in order to prevent the welding defects. In this paper, the distribution of argon arc contaminated as function of frequency with nitrogen in pulsed TIG welding is elucidated. The nitrogen concentration, the radial flow velocity, the arc temperature were calculated using the EMTF simulation when the time reached at the base current. As a result, the nitrogen concentration into the arc became low with increasing the frequency The diffusion coefficient decreased because of the decrement of temperature over 4000 K. In this case, the nitrogen concentration became low near the anode. Therefore, the nitrogen concentration became low because the frequency is high.

Nitrogen Forms Influence Microcystin Concentration and Composition via Changes in Cyanobacterial Community Structure

PubMed Central

Monchamp, Marie-Eve; Pick, Frances R.; Beisner, Beatrix E.; Maranger, Roxane

2014-01-01

The eutrophication of freshwaters is a global health concern as lakes with excess nutrients are often subject to toxic cyanobacterial blooms. Although phosphorus is considered the main element regulating cyanobacterial biomass, nitrogen (N) concentration and more specifically the availability of different N forms may influence the overall toxicity of blooms. In this study of three eutrophic lakes prone to cyanobacterial blooms, we examined the effects of nitrogen species and concentrations and other environmental factors in influencing cyanobacterial community structure, microcystin (MC) concentrations and MC congener composition. The identification of specific MC congeners was of particular interest as they vary widely in toxicity. Different nitrogen forms appeared to influence cyanobacterial community structure leading to corresponding effects on MC concentrations and composition. Total MC concentrations across the lakes were largely explained by a combination of abiotic factors: dissolved organic nitrogen, water temperature and ammonium, but Microcystis spp. biomass was overall the best predictor of MC concentrations. Environmental factors did not appear to affect MC congener composition directly but there were significant associations between specific MC congeners and particular species. Based on redundancy analyses (RDA), the relative biomass of Microcystis aeruginosa was associated with MC-RR, M. wesenbergii with MC-LA and Aphanizomenon flos-aquae with MC-YR. The latter two species are not generally considered capable of MC production. Total nitrogen, water temperature, ammonium and dissolved organic nitrogen influenced the cyanobacterial community structure, which in turn resulted in differences in the dominant MC congener and the overall toxicity. PMID:24427318

Nutrient and chlorophyll relations in selected streams of the New England Coastal Basins in Massachusetts and New Hampshire, June-September 2001

USGS Publications Warehouse

Riskin, Melissa L.; Deacon, J.R.; Liebman, M.L.; Robinson, K.W.

2003-01-01

The U.S. Environmental Protection Agency is developing guidance to assist states with defining nutrient criteria for rivers and streams and to better describe nutrient-algal relations. As part of this effort, 13 wadeable stream sites were selected, primarily in eastern Massachusetts, for a nutrient-assessment study during the summer of 2001. The sites represent a range of water-quality impairment conditions (reference, moderately impaired, impaired) based on state regulatory agency assessments and previously assessed nitrogen, phosphorus, and dissolved-oxygen data. In addition, a combination of open- and closed-canopy locations were sampled at six of the sites to investigate the effect of sunlight on algal growth. Samples for nutrients and for chlorophyll I from phytoplankton and periphyton were collected at all stream sites. Total nitrogen (dissolved nitrite + nitrate + total ammonia + organic nitrogen) and total phosphorus (phosphorus in an unfiltered water sample) concentrations were lowest at reference sites and highest at impaired sites. There were statistically significant differences (p < 0.05) among reference, moderately impaired, and impaired sites for total nitrogen and total phosphorus. Chlorophyll a concentrations from phytoplankton were not significantly different among site impairment designations. Concentrations of chlorophyll a from periphyton were highest at nutrient-impaired open-canopy sites. Chlorophyll a concentrations from periphyton samples were positively correlated with total nitrogen and total phosphorus at the open- and closed-canopy sites. Correlations were higher at open-canopy sites (p < 0.05, rho = 0.64 to 0.71) than at closed-canopy sites (p < 0.05, rho = 0.36 to 0.40). Statistically significant differences in the median concentrations of chlorophyll a from periphyton samples were observed between the open- and closed-canopy sites (p < 0.05). Total nitrogen and total phosphorus data from moderately impaired and impaired sites in this study exceeded the preliminary U.S. Environmental Protection Agency nutrient criteria values for the coastal region of New England. In an effort to establish more appropriate nutrient and chlorophyll criteria for streams in the New England coastal region, relations between total nitrogen and total phosphorus to periphyton chlorophyll a in wadeable streams from this study were quantified to present potential techniques for determining nutrient concentrations. Linear regression was used to estimate the total nitrogen and total phosphorus concentrations that corresponded to various chlorophyll a concentrations. On the basis of this relation, a median concentration for moderately enriched streams of 21 milligrams per square meter (mg/m2) of periphyton chlorophyll a from the literature corresponded to estimated concentrations of 1.3 milligrams per liter (mg/L) for total nitrogen and 0.12 mg/L for total phosphorus. The median concentration for periphyton chlorophyll a from the literature is similar to the 50th-percentile concentration of periphyton chlorophyll a (17 mg/m2) calculated with the data from open-canopy sites in this study. The 25th-percentile concentration for periphyton chlorophyll a of all open-canopy sites (5.2 mg/m2) and the 75th-percentile concentration for periphyton chlorophyll a of open-canopy reference sites (16 mg/m2) also were plotted to provide additional estimates and methods for developing total nitrogen and total phosphorus criteria. The 25th-percentile concentrations of total nitrogen and total phosphorus were calculated based on all sites in this study and were used as another potential criteria estimation. A concentration of 0.64 mg/L for total nitrogen and 0.030 mg/L for total phosphorus were calculated. As another possible method to develop threshold concentrations, the 10th-percentile concentrations of total nitrogen and total phosphorus were calculated based on all the impaired sites in this study. A concentration threshold of 0

Zooming in on aquatic denitrification hot spots

NASA Astrophysics Data System (ADS)

Schultz, Colin

2011-06-01

Inorganic nitrogen is an important resource for marine and aquatic ecosystems, acting as a fertilizer for phytoplankton and aquatic plants. When nitrogen concentrations soar, algae blooms can occur. Subsequently, when the algae blooms die, their decomposition can consume most of the available dissolved oxygen, negatively affecting the ecosystem as a whole. Creeks and streams act as strong controls, regulating downstream nitrogen concentrations, and researchers have been zooming in on hyporheic zones—zones where water flows through the sediment alongside the surface water—as possible hot spots of activity in the nitrogen cycle. Using a stable isotope tracer, Zarnetske et al. tracked the evolution of a nitrogen addition as it flowed through a heavily instrumented gravel bar in Drift Creek, in Oregon. The researchers found that the gravel bar could act as either a source or a sink of inorganic nitrogen, depending on how long it took for the water to make its way through the bar. When the creek water took longer to pass through the hyporheic zone, nitrogen levels were reduced significantly through denitrification, while any water that traveled quickly could have its inorganic nitrogen concentrations increased by nitrification. The authors note that a context-dependent effect of individual hyporheic zones on inorganic nitrogen concentrations could have important implications for attempts to estimate the effects of a watershed on the nitrogen cycle. (Journal of Geophysical Research-Biogeosciences, doi:10.1029/ 2010JG001356, 2011)

Mathematical model of a parallel plate ammonia electrolyzer for combined wastewater remediation and hydrogen production.

PubMed

Estejab, Ali; Daramola, Damilola A; Botte, Gerardine G

2015-06-15

A mathematical model was developed for the simulation of a parallel plate ammonia electrolyzer to convert ammonia in wastewater to nitrogen and hydrogen under basic conditions. The model consists of fundamental transport equations, the ammonia oxidation kinetics at the anode, and the hydrogen evolution kinetics at the cathode of the electrochemical reactor. The model shows both qualitative and quantitative agreement with experimental measurements at ammonia concentrations found within wastewater (200-1200 mg L(-1)). The optimum electrolyzer performance is dependent on both the applied voltage and the inlet concentrations. Maximum conversion of ammonia to nitrogen at the rates of 0.569 and 0.766 mg L(-1) min(-1) are achieved at low (0.01 M NH4Cl and 0.1 M KOH) and high (0.07 M NH4Cl and 0.15 M KOH) inlet concentrations, respectively. At high and low concentrations, an initial increase in the cell voltage will cause an increase in the system response - current density generated and ammonia converted. These system responses will approach a peak value before they start to decrease due to surface blockage and/or depletion of solvated species at the electrode surface. Furthermore, the model predicts that by increasing the reactant and electrolyte concentrations at a certain voltage, the peak current density will plateau, showing an asymptotic response. Copyright © 2015 Elsevier Ltd. All rights reserved.

Fixation of nitrogen in the presence of water vapor

DOEpatents

Harteck, Paul

1984-01-01

A process for the fixation of nitrogen is disclosed which comprises combining a mixture of nitrogen, oxygen, metal oxide and water vapor, initially heating the combination to initiate a reaction which forms nitrate, but at a temperature and pressure range below the dissociation pressure of the nitrate. With or without the water component, the yield of fixed nitrogen is increased by the use of a Linde Molecular Sieve Catalyst.

THE EFFECTS OF NITROGEN LOADING AND FRESHWATER RESIDENCE TIME ON THE ESTUARINE ECOSYSTEM

EPA Science Inventory

A simple mechanistic model, designed to predict annual average concentrations of total nitrogen (TN) concentrations from nitrogen inputs and freshwater residence time in estuaries, was applied to data for several North American estuaries from previously published literature. The ...

Depressurization and two-phase flow of water containing high levels of dissolved nitrogen gas

NASA Technical Reports Server (NTRS)

Simoneau, R. J.

1981-01-01

Depressurization of water containing various concentrations of dissolved nitrogen gas was studied. In a nonflow depressurization experiment, water with very high nitrogen content was depressurized at rates from 0.09 to 0.50 MPa per second and a metastable behavior which was a strong function of the depressurization rate was observed. Flow experiments were performed in an axisymmetric, converging diverging nozzle, a two dimensional, converging nozzle with glass sidewalls, and a sharp edge orifice. The converging diverging nozzle exhibited choked flow behavior even at nitrogen concentration levels as low as 4 percent of the saturation level. The flow rates were independent of concentration level. Flow in the two dimensional, converging, visual nozzle appeared to have a sufficient pressure drop at the throat to cause nitrogen to come out of solution, but choking occurred further downstream. The orifice flow motion pictures showed considerable oscillation downstream of the orifice and parallel to the flow. Nitrogen bubbles appeared in the flow at back pressures as high as 3.28 MPa, and the level at which bubbles were no longer visible was a function of nitrogen concentration.

Effect of ammonium nitrogen concentration on the ammonia-oxidizing bacteria community in a membrane bioreactor for the treatment of anaerobically digested swine wastewater.

PubMed

Sui, Qianwen; Liu, Chong; Dong, Hongmin; Zhu, Zhiping

2014-09-01

A membrane bioreactor (MBR) was developed for the treatment of anaerobically digested swine wastewater and to investigate the effect of ammonium nitrogen concentration on biological nitrogen removal and ammonia-oxidizing bacteria (AOB) community structures. The MBR achieved a high NH4(+)-N removal efficiency of 0.08 kgNMLSS(-1)d(-1) and removed 95% of the influent NH4(+)-N. The TN removal rate was highest of 82.62% at COD/TN and BOD5/TN ratios of 8.76 ± 0.30 and 3.02 ± 0.09, respectively. With the decrease in ammonium nitrogen concentrations, the diversity of the AOB community declined and showed a simple pattern of DGGE. However, the AOB population size remained high, with abundance of 10(7)-10(9) copies mL(-1). With the decrease of ammonium nitrogen concentrations, Nitrosomonas eutropha gradually disappeared, whereas Nitrosomonas sp. OZK11 showed constant adaptability to survive during each treatment stage. The selective effect of ammonium concentration on AOB species could be due to the affinity for NH4(+)-N. In this study, the changes of ammonium nitrogen concentrations in digested swine wastewater were found to have selective effects on the composition of AOB community, and biological nitrogen removal was improved by optimising the influencing parameters. Copyright © 2014. Published by Elsevier B.V.

[Spatiotemporal characteristics of nitrogen and phosphorus in a mountainous urban lake].

PubMed

Bao, Jing-Yue; Bao, Jian-Guo; Li, Li-Qing

2014-10-01

Longjing Lake in Chongqing Expo Garden is a typical representative of mountainous urban lake. Based on water quality monitoring of Longjing Lake, spatiotemporal characteristics of nitrogen and phosphorus and their relations were analyzed, combined with natural and human factors considered. The results indicated that annual average concentrations of TN and TP in overall lake were (1.42 ± 0.46) mg · L(-1) and (0.09 ± 0.03) mg · L(-1), nitrogen and phosphorus concentrations fluctuated seasonally which were lower during the flooding season than those during the dry season. Nitrogen and phosphorus concentration in main water area, open water areas and bay areas of Longjing Lake were distributed with temporal and spatial heterogeneity by different regional influencing factors. The seasonal variation of the main water area was basically consistent with overall lake. Two open water areas respectively connected the main water area with the upstream region, bay areas. TN and TP concentrations were gradually reduced along the flow direction. Upstream water quality and surrounding park functional layout impacted nitrogen and phosphorus nutrient concentrations of open water areas. Nutrient concentrations of typical bay areas were higher than those of main water area and open water areas. The mean mass fraction of PN/TN and PP/TP accounted for a large proportion (51.7% and 72.8%) during the flooding season, while NO(3-)-N/TN and SRP/TP accounted for more (42.0% and 59.4%) during the dry season. The mass fraction of ammonia nitrogen and dissolved organic nitrogen in total nitrogen were relatively stable. The annual mean of N/P ratio was 18.429 ± 7.883; the period of nitrogen limitation was 5.3% while was 21.2% for phosphorus limitation.

[Effects of different concentrations of nitrogen and phosphorus on growth and active components of Salvia miltiorrhiza].

PubMed

Xia, Gui-Hui; Wang, Qiu-Ling; Wang, Wen-Quan; Hou, Jun-Ling; Song, Qing-Yan; Luo, Lin; Zhang, Dou-Dou; Yang, Xiang

2016-11-01

With annual Salvia miltiorrhiza seedlings as experimental material, using "3414" optimal regression design recommended by the Ministry of Agriculture and regularly watered with nutrient solution, through the dynamic sampling of S. miltiorrhiza in different growing stages, and the growth index, dry weight of plant root and content of active components were measured. The potted experiments were applied to study the effects of different nitrogen and phosphorus ratios on the growth, dry matter accumulation and accumulation of active components of S. miltiorrhiza, in order to explore a compatible fertilization method of nitrogen and phosphorus ratio that are suitable for production and quality of S. miltiorrhiza. The results reported as follows：①High concentrations of nitrogen fertilizer was beneficial to dry matter accumulation of S. miltiorrhiza aerial parts, and low concentration of nitrogen fertilizer transferred the dry matter accumulation to underground, and N1P1 could make the transfer ahead of time;②Regression analysis showed that in the early growth stage (before early July), we could use the nitrogen and phosphorus as basic fertilizer at a concentration of 1.521,0.355 g•L⁻¹ respectively to promote the growth of S. miltiorrhiza and at a concentration of 2.281,0.710 g•L⁻¹ respectively to promote the dry matter accumulation of root (after mid-August);③Five kinds of active components of S. miltiorrhiza decreased with the increase of nitrogen concentration, and increased with the increase of the concentration of phosphate fertilizer. Nitrogenous fertilizer, phosphate fertilizer in N-P=2∶3 ratio was more suitable for the accumulation of salvianolic acids, in N-P=1∶2 ratio was more suitable for the accumulation of tanshinone. Copyright© by the Chinese Pharmaceutical Association.

Regional patterns of total nitrogen concentrations in the National Rivers and Streams Assessment

EPA Science Inventory

Patterns of nitrogen concentrations in streams sampled by the National Rivers and Streams Assessment (NRSA) were examined semi-quantitatively to identify regional differences in stream nitrogen levels. The data were categorized and analyzed by watershed size classes to reveal pat...

Biological nitrogen removal using soil columns for the reuse of reclaimed water: Performance and microbial community analysis.

PubMed

Sun, Jiaji; Chen, Lei; Rene, Eldon R; Hu, Qian; Ma, Weifang; Shen, Zhenyao

2018-07-01

The main aim of this study was to remove nitrogen compounds from reclaimed water and reuse the water in semi-arid riverine lake systems. In order to assess the nitrogen removal efficiencies in different natural environments, laboratory scale column experiments were performed using sterilized soil (SS), silty clay (SC), soil with submerged plant (SSP) and biochar amendment soil (BCS). The initial concentration of NO 3 - -N and the flow rate was maintained constant at 15 mg L -1 and 0.6 ± 0.1 m d -1 , respectively. Among the tested columns, both SSP and BCS were able to achieve NO 3 - -N levels <0.2 mg L -1 in the treated reclaimed water. The results from bacterial community structure analysis, using 454 pyrosequencing of 16s rRNA genes, showed that the dominant denitrifier was Bacillus at the genera level. Copyright © 2018 Elsevier Ltd. All rights reserved.

Cell signaling by reactive nitrogen and oxygen species in atherosclerosis

NASA Technical Reports Server (NTRS)

Patel, R. P.; Moellering, D.; Murphy-Ullrich, J.; Jo, H.; Beckman, J. S.; Darley-Usmar, V. M.

2000-01-01

The production of reactive oxygen and nitrogen species has been implicated in atherosclerosis principally as means of damaging low-density lipoprotein that in turn initiates the accumulation of cholesterol in macrophages. The diversity of novel oxidative modifications to lipids and proteins recently identified in atherosclerotic lesions has revealed surprising complexity in the mechanisms of oxidative damage and their potential role in atherosclerosis. Oxidative or nitrosative stress does not completely consume intracellular antioxidants leading to cell death as previously thought. Rather, oxidative and nitrosative stress have a more subtle impact on the atherogenic process by modulating intracellular signaling pathways in vascular tissues to affect inflammatory cell adhesion, migration, proliferation, and differentiation. Furthermore, cellular responses can affect the production of nitric oxide, which in turn can strongly influence the nature of oxidative modifications occurring in atherosclerosis. The dynamic interactions between endogenous low concentrations of oxidants or reactive nitrogen species with intracellular signaling pathways may have a general role in processes affecting wound healing to apoptosis, which can provide novel insights into the pathogenesis of atherosclerosis.

Simulated groundwater flow paths, travel time, and advective transport of nitrogen in the Kirkwood-Cohansey aquifer system, Barnegat Bay–Little Egg Harbor Watershed, New Jersey

USGS Publications Warehouse

Voronin, Lois M.; Cauller, Stephen J.

2017-07-31

Elevated concentrations of nitrogen in groundwater that discharges to surface-water bodies can degrade surface-water quality and habitats in the New Jersey Coastal Plain. An analysis of groundwater flow in the Kirkwood-Cohansey aquifer system and deeper confined aquifers that underlie the Barnegat Bay–Little Egg Harbor (BB-LEH) watershed and estuary was conducted by using groundwater-flow simulation, in conjunction with a particle-tracking routine, to provide estimates of groundwater flow paths and travel times to streams and the BB-LEH estuary.Water-quality data from the Ambient Groundwater Quality Monitoring Network, a long-term monitoring network of wells distributed throughout New Jersey, were used to estimate the initial nitrogen concentration in recharge for five different land-use classes—agricultural cropland or pasture, agricultural orchard or vineyard, urban non-residential, urban residential, and undeveloped. Land use at the point of recharge within the watershed was determined using a geographic information system (GIS). Flow path starting locations were plotted on land-use maps for 1930, 1973, 1986, 1997, and 2002. Information on the land use at the time and location of recharge, time of travel to the discharge location, and the point of discharge were determined for each simulated flow path. Particle-tracking analysis provided the link from the point of recharge, along the particle flow path, to the point of discharge, and the particle travel time. The travel time of each simulated particle established the recharge year. Land use during the year of recharge was used to define the nitrogen concentration associated with each flow path. The recharge-weighted average nitrogen concentration for all flow paths that discharge to the Toms River upstream from streamflow-gaging station 01408500 or to the BB-LEH estuary was calculated.Groundwater input into the Barnegat Bay–Little Egg Harbor estuary from two main sources— indirect discharge from base flow to streams that eventually flow into the bay and groundwater discharge directly into the estuary and adjoining coastal wetlands— is summarized by quantity, travel time, and estimated nitrogen concentration. Simulated average groundwater discharge to streams in the watershed that flow into the BB-LEH estuary is approximately 400 million gallons per day. Particle-tracking results indicate that the travel time of 56 percent of this discharge is less than 7 years. Fourteen percent of the groundwater discharge to the streams in the BB-LEH watershed has a travel time of less than 7 years and originates in urban land. Analysis of flow-path simulations indicate that approximately 13 percent of the total groundwater flow through the study area discharges directly to the estuary and adjoining coastal wetlands (approximately 64 million gallons per day). The travel time of 19 percent of this discharge is less than 7 years. Ten percent of this discharge (1 percent of the total groundwater flow through the study area) originates in urban areas and has a travel time of less than 7 years. Groundwater that discharges to the streams that flow into the BB-LEH, in general, has shorter travel times, and a higher percentage of it originates in urban areas than does direct groundwater discharge to the Barnegat Bay–Little Egg Harbor estuary.The simulated average nitrogen concentration in groundwater that discharges to the Toms River, upstream from streamflow-gaging station 01408500 was computed and compared to summary concentrations determined from analysis of multiple surface-water samples. The nitrogen concentration in groundwater that discharges directly to the estuary and adjoining coastal wetlands is a current data gap. The particle tracking methodology used in this study provides an estimate of this concentration."

Revealing the Origin of Activity in Nitrogen-Doped Nanocarbons towards Electrocatalytic Reduction of Carbon Dioxide.

PubMed

Xu, Junyuan; Kan, Yuhe; Huang, Rui; Zhang, Bingsen; Wang, Bolun; Wu, Kuang-Hsu; Lin, Yangming; Sun, Xiaoyan; Li, Qingfeng; Centi, Gabriele; Su, Dangsheng

2016-05-23

Carbon nanotubes (CNTs) are functionalized with nitrogen atoms for reduction of carbon dioxide (CO2 ). The investigation explores the origin of the catalyst's activity and the role of nitrogen chemical states therein. The catalysts show excellent performances, with about 90 % current efficiency for CO formation and stability over 60 hours. The Tafel analyses and density functional theory calculations suggest that the reduction of CO2 proceeds through an initial rate-determining transfer of one electron to CO2 , which leads to the formation of carbon dioxide radical anion (CO2 (.-) ). The initial reduction barrier is too high on pristine CNTs, resulting in a very high overpotentials at which the hydrogen evolution reaction dominates over CO2 reduction. The doped nitrogen atoms stabilize the radical anion, thereby lowering the initial reduction barrier and improving the intrinsic activity. The most efficient nitrogen chemical state for this reaction is quaternary nitrogen, followed by pyridinic and pyrrolic nitrogen. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Water-quality assessment of the Trinity River Basin, Texas - Nutrients in streams draining an agricultural and an urban area, 1993-95

USGS Publications Warehouse

Land, Larry F.; Shipp, Allison A.

1996-01-01

Water samples collected from streams draining an agricultural area in the west-central part of the Trinity River Basin upstream from the Richland-Chambers Reservoir and from streams draining an urban area in the Dallas-Fort Worth metropolitan area during March 1993 - September 1995 were analyzed for nutrients (nitrogen and phosphorus compounds). A comparison of the data for agricultural and urban streams shows the maximum concentration of total nitrogen is from an urban stream and the maximum concentration of total phosphorus is from an agricultural stream. One-half of the samples have total nitrogen concentrations equal to or less than 1.1 and 1.0 milligrams per liter in the agricultural and urban streams, respectively; and one-half of the samples have total phosphorous concentrations equal to or less than 0.04 and 0.05 milligram per liter in the agricultural and urban streams, respectively. The highest concentrations of total nitrogen in both types of streams are in the spring. The minimum concentrations of total nitrogen are during the summer in the agricultural streams and during the winter in the urban streams. Concentrations of total phosphorus in agricultural streams show negligible seasonal variability. The highest concentrations of total phosphorus are in spring and possibly late summer in the urban streams. In the midrange of streamflow in the urban streams and throughout the range of streamflow in the agricultural streams, concentrations of total nitrogen increase. Concentrations of total phosphorus increase with streamflow in the middle and upper ranges of streamflow in both agricultural and urban streams.

Indirect Measurement Of Nitrogen In A Multi-Component Gas By Measuring The Speed Of Sound At Two States Of The Gas.

DOEpatents

Morrow, Thomas B.; Behring, II, Kendricks A.

2004-10-12

A methods of indirectly measuring the nitrogen concentration in a gas mixture. The molecular weight of the gas is modeled as a function of the speed of sound in the gas, the diluent concentrations in the gas, and constant values, resulting in a model equation. Regression analysis is used to calculate the constant values, which can then be substituted into the model equation. If the speed of sound in the gas is measured at two states and diluent concentrations other than nitrogen (typically carbon dioxide) are known, two equations for molecular weight can be equated and solved for the nitrogen concentration in the gas mixture.

Seasonal changes of concentrations of inorganic and organic nitrogen in coastal marine sediments

NASA Astrophysics Data System (ADS)

Yamada, Hisashi; Kayama, Mitsu; Fujisawa, Kuniyasu

1987-05-01

The seasonal fluctuations of the concentration of nitrogenous compounds in sediments was investigated for three regions of the Seto Inland Sea in Japan; the variation of nitrogenous compounds in sediments was also studied in a laboratory experiment. The amounts of ammonium, dissolved organic nitrogen, nitrite and nitrate, as percentages of the dissolved total nitrogen of the interstitial water, were in the ranges of 47-99%, 10-50%, 0·1-0·6% and 0·3-4·1%, respectively. Ammonium was the major component and organic nitrogen was the next most important. The concentrations of these nitrogenous compounds changed seasonally: dissolved total nitrogen was higher in the warm month of September than in May; ammonium increased in warm months and decreased in cold months, but nitrite and nitrate increased in cold months. It was possible to explain the seasonal fluctuation of nitrogenous compounds in terms of the rates of the metabolic pathways of nitrogen in the sediments. Ammonium was not necessarily correlated with dissolved organic nitrogen. From this, it was considered that ammonium did not occur from solubilization of particulate organic nitrogen followed by mineralization, but from direct mineralization of particulate organic nitrogen in sediments. For the sediments of Suho Nada, Hiuchi Nada and station B-47 in Beppu Bay, the ratio of dissolved ammonium to adsorbed ammonium in the sediments was in the range 10-25%, but the ratio was 60-70% of adsorbed ammonium in the considerably anaerobic sediments at station B-45 in Beppu Bay. The ratio of dissolved ammonium to adsorbed ammonium increased with the increase of the concentration of sulfide in sediments. It was recognized that the anaerobic conditions of the sediments led to the dissolution of adsorbed ammonium.

Litter Decomposition in a Semiarid Dune Grassland: Neutral Effect of Water Supply and Inhibitory Effect of Nitrogen Addition.

PubMed

Li, Yulin; Ning, Zhiying; Cui, Duo; Mao, Wei; Bi, Jingdong; Zhao, Xueyong

2016-01-01

The decomposition of plant material in arid ecosystems is considered to be substantially controlled by water and N availability. The responses of litter decomposition to external N and water, however, remain controversial, and the interactive effects of supplementary N and water also have been largely unexamined. A 3.5-year field experiment with supplementary nitrogen and water was conducted to assess the effects of N and water addition on mass loss and nitrogen release in leaves and fine roots of three dominant plant species (i.e., Artemisia halondendron, Setaria viridis, and Phragmites australis) with contrasting substrate chemistry (e.g. N concentration, lignin content in this study) in a desertified dune grassland of Inner Mongolia, China. The treatments included N addition, water addition, combination of N and water, and an untreated control. The decomposition rate in both leaves and roots was related to the initial litter N and lignin concentrations of the three species. However, litter quality did not explain the slower mass loss in roots than in leaves in the present study, and thus warrant further research. Nitrogen addition, either alone or in combination with water, significantly inhibited dry mass loss and N release in the leaves and roots of the three species, whereas water input had little effect on the decomposition of leaf litter and fine roots, suggesting that there was no interactive effect of supplementary N and water on litter decomposition in this system. Furthermore, our results clearly indicate that the inhibitory effects of external N on dry mass loss and nitrogen release are relatively strong in high-lignin litter compared with low-lignin litter. These findings suggest that increasing precipitation hardly facilitates ecosystem carbon turnover but atmospheric N deposition can enhance carbon sequestration and nitrogen retention in desertified dune grasslands of northern China. Additionally, litter quality of plant species should be considered when modelling the carbon cycle and nutrient dynamics of this system.

Plant Nitrogen Uptake in Terrestrial Biogeochemical Models

NASA Astrophysics Data System (ADS)

Marti, Alejandro; Cox, Peter; Sitch, Stephen; Jones, Chris; Liddicoat, spencer

2013-04-01

Most terrestrial biogeochemical models featured in the last Intergovernmental Panel on Climate Change (IPPC) Assessment Report highlight the importance of the terrestrial Carbon sequestration and feedbacks between the terrestrial Carbon cycle and the climate system. However, these models have been criticized for overestimating predicted Carbon sequestration and its potential climate feedback when calculating the rate of future climate change because they do not account for the Carbon sequestration constraints caused by nutrient limitation, particularly Nitrogen (N). This is particularly relevant considering the existence of a substantial deficit of Nitrogen for plants in most areas of the world. To date, most climate models assume that plants have access to as much Nitrogen as needed, but ignore the nutrient requirements for new vegetation growth. Determining the natural demand and acquisition for Nitrogen and its associated resource optimization is key when accounting for the Carbon sequestration constrains caused by nutrient limitation. The few climate models that include C-N dynamics have illustrated that the stimulation of plant growth over the coming century may be two to three times smaller than previously predicted. This reduction in growth is partially offset by an increase in the availability of nutrients resulting from an accelerated rate of decomposition of dead plants and other organic matter that occurring with a rise in temperature. However, this offset does not counterbalance the reduced level of plant growth calculated by natural nutrient limitations. Additionally, Nitrogen limitation is also expected to become more pronounced in some ecosystems as atmospheric CO2 concentration increases; resulting in less new growth and higher atmospheric CO2 concentrations than originally expected. This study compares alternative models of plant N uptake as found in different terrestrial biogeochemical models against field measurements, and introduces a new N-uptake model to the Joint UK Land Environment Simulator (JULES).. Acknowledgements This work has been funded by the European Commission FP7-PEOPLE-ITN-2008 Marie Curie Action: "Greencycles II: FP7-PEOPLE-ITN-2008 Marie Curie Action: "Networks for Initial Training"

Litter Decomposition in a Semiarid Dune Grassland: Neutral Effect of Water Supply and Inhibitory Effect of Nitrogen Addition

PubMed Central

Li, Yulin; Ning, Zhiying; Cui, Duo; Mao, Wei; Bi, Jingdong; Zhao, Xueyong

2016-01-01

Background The decomposition of plant material in arid ecosystems is considered to be substantially controlled by water and N availability. The responses of litter decomposition to external N and water, however, remain controversial, and the interactive effects of supplementary N and water also have been largely unexamined. Methodology/Principal Findings A 3.5-year field experiment with supplementary nitrogen and water was conducted to assess the effects of N and water addition on mass loss and nitrogen release in leaves and fine roots of three dominant plant species (i.e., Artemisia halondendron, Setaria viridis, and Phragmites australis) with contrasting substrate chemistry (e.g. N concentration, lignin content in this study) in a desertified dune grassland of Inner Mongolia, China. The treatments included N addition, water addition, combination of N and water, and an untreated control. The decomposition rate in both leaves and roots was related to the initial litter N and lignin concentrations of the three species. However, litter quality did not explain the slower mass loss in roots than in leaves in the present study, and thus warrant further research. Nitrogen addition, either alone or in combination with water, significantly inhibited dry mass loss and N release in the leaves and roots of the three species, whereas water input had little effect on the decomposition of leaf litter and fine roots, suggesting that there was no interactive effect of supplementary N and water on litter decomposition in this system. Furthermore, our results clearly indicate that the inhibitory effects of external N on dry mass loss and nitrogen release are relatively strong in high-lignin litter compared with low-lignin litter. Conclusion/Significance These findings suggest that increasing precipitation hardly facilitates ecosystem carbon turnover but atmospheric N deposition can enhance carbon sequestration and nitrogen retention in desertified dune grasslands of northern China. Additionally, litter quality of plant species should be considered when modelling the carbon cycle and nutrient dynamics of this system. PMID:27617439

Assessment of total nitrogen in the upper Connecticut River basin in New Hampshire, Vermont, and Massachusetts, December 2002-September 2005

USGS Publications Warehouse

Deacon, Jeffrey R.; Smith, Thor E.; Johnston, Craig M.; Moore, Richard B.; Blake, Laura J.; Weidman, Rebecca M.

2006-01-01

A study of total nitrogen concentrations and loads was conducted from December 2002 to September 2005 at 13 river sites in the upper Connecticut River Basin. Ten sites were selected to represent contributions of nitrogen from forested, agricultural, and urban land. Three sites were distributed spatially on the main stem of the Connecticut River to assess the cumulative total nitrogen loads. To further improve the understanding of the sources and concentrations and loads of total nitrogen in the upper Connecticut River Basin, ambient surface water-quality sampling was supplemented with sampling of effluent from 19 municipal and paper mill wastewater-treatment facilities. Mean concentrations of total nitrogen ranged from 0.19 to 2.8 milligrams per liter (mg/L) at river sampling sites. Instantaneous mean loads of total nitrogen ranged from 162 to 58,300 pounds per day (lb/d). Estimated mean annual loads of total nitrogen ranged from 49,100 to 21.6 million pounds per year (lb/yr) with about 30 to 55 percent of the loads being transported during the spring. The estimated mean annual yields of total nitrogen ranged from 1,190 to 7,300 pounds per square mile per year (lb/mi2)/yr. Mean concentrations of total nitrogen ranged from 4.4 to 30 mg/L at wastewater-treatment sampling sites. Instantaneous mean loads of total nitrogen from municipal wastewater-treatment facilities ranged from 36 to 1,780 lb/d. Instantaneous mean loads of total nitrogen from paper mill wastewater-treatment facilities ranged from 96 to 160 lb/d. The median concentration of total nitrogen was 0.24 mg/L at forested sites, 0.48 mg/L at agricultural sites, 0.54 mg/L at urban sites, 0.48 mg/L at main-stem sites, and 14 mg/L at wastewater-treatment sites. Concentrations of total nitrogen at forested sites were significantly less than at all other site types (p0.05) but were significantly greater (p<0.05) than at forested sites and significantly less than concentrations at wastewater-treatment sites (p<0.05). Total nitrogen concentrations at wastewater-treatment sites were significantly different from all other site types (p<0.05). Annual yields of total nitrogen ranged from 732 to 1,920 (lb/mi2)/yr at forested sites; 1,550 to 2,980 (lb/mi2)/yr at agricultural sites; 1,280 to 1,860 (lb/mi2)/yr at urban sites that were not directly affected by wastewater effluent; 7,090 to 7,770 (lb/mi2)/yr at an urban site directly affected by wastewater effluent; and 1,300 to 2,390 (lb/mi2)/yr at main-stem sites. In this study, the mean annual load and yield of total nitrogen at the Connecticut River at Wells River, VT, was estimated at 4.47 million lb/yr and 1,690 (lb/mi2)/yr, respectively. The mean annual load and yield of total nitrogen at the Connecticut River at North Walpole, NH, was estimated at 9.60 million lb/yr and 1,750 (lb/mi2)/yr, respectively. The mean annual load and yield of total nitrogen leaving the upper Connecticut River Basin, as estimated at the Connecticut River at Thompsonville, CT, was 21.6 million lb/yr and 2,230 (lb/mi2)/yr, respectively.

Decomposition of 2,4,6-trinitrotoluene (TNT) by gamma irradiation.

PubMed

Lee, Byungjin; Lee, Myunjoo

2005-12-01

The purpose of this study was to evaluate the potential of gamma irradiation to decompose 2,4,6-trinitrotoluene (TNT) in an aqueous solution; the concentration range of the TNT solution was 0.11-0.44 mmol/L. The decomposition rate of TNT by gamma irradiation was pseudo-first-order kinetic over the applied initial concentrations. The dose constant was strongly dependent on the initial concentration of TNT. Increasing the concentration of dissolved oxygen in the solution was more effective on the decomposition of TNT as well as its mineralization. The required irradiation dose to remove 90% of initial TNT (0.44 mmol/L) was 58, 41, 32, 28, and 25 kGy at the dissolved oxygen concentration of 0.025, 0.149, 0.3, 0.538, and 0.822 mmol/L, respectively. However, TOC still remained as 30% of the initial TOC (3.19 mmol/L) when 200 kGy irradiation dose was applied to the TNT solution (0.44 mmol/L) containing dissolved oxygen of 0.822 mmol/L. The removal of the TNT was more efficient at a pH below 3 and at a pH above 11 than at neutral pH (pH 5-9). The required irradiation dose to remove over 99% of the initial TNT (0.44 mmol/L) was 39, 76, and 10 kGy at pH 2, 7, and 13, respectively. The dose constant was increased 1.6-fold and over 15.6-fold at pH 2 and 13, respectively, compared to that at pH 7. When an irradiation dose of 200 kGy was applied, the removal efficiencies of the TOC (initial concentration 3.19 mmol/L) were 91, 46, and 53% at pH 2, 7, and 13, respectively. Ammonia and nitrate were detected as the main nitrogen byproducts of TNT, and glyoxalic acid and oxalic acid were detected as organic byproducts.

Trends in nitrogen concentration and nitrogen loads entering the South Shore Estuary Reserve from streams and ground-water discharge in Nassau and Suffolk counties, Long Island, New York, 1952–97

USGS Publications Warehouse

Monti, Jack; Scorca, Michael P.

2003-01-01

The 13 major south-shore streams in Nassau and Suffolk Counties, Long Island, New York with adequate long-term (1971-97) water-quality records, and 192 south-shore wells with sufficient water-quality data, were selected for analysis of geographic, seasonal, and long-term trends in nitrogen concentration. Annual total nitrogen loads transported to the South Shore Estuary Reserve (SSER) from 11 of these streams were calculated using long-term discharge records. Nitrogen loads from shallow and deep ground water also were calculated using simulated ground-water discharge of 1968-83 hydrologic conditions.Long-term declines in stream discharge occurred in East Meadow Brook, Bellmore Creek and Massapequa Creek in response to extensive sewering in Nassau County. The smallest longterm annual discharge to the SSER was from the westernmost stream, Pines Brook, which is in an area in which the water table has been lowered by sewers since 1952. The three largest average annual discharges to the SSER were from the Connetquot River, Carlls River, and Carmans River in Suffolk County; the discharges from each of these streams were at least twice those of the other streams considered in this study.Total nitrogen concentrations in streams show a geographic trend with a general eastward increase in median total nitrogen concentration in Nassau County and a decreasing trend from Massapequa Creek eastward into Suffolk County. Total nitrogen concentrations in streams generally are lowest during summer and highest in winter as a result of seasonal fluctuations in chemical reactions and biological activity. The greatest seasonal difference in median total nitrogen concentration was at Carlls River with values of 3.4 and 4.2 mg/L (milligrams per liter) as N during summer (April through September) and winter (October through March), respectively. Streams affected by the completion of sewer districts show long-term (1971-97) trends of decreasing total nitrogen concentration and streams showing an increase in total nitrogen concentration are in unsewered areas with increased urbanization.Discharges from shallow ground water (upper glacial aquifer) and deep ground water (upper part of Magothy aquifer) were simulated from a ground-water-flow model calibrated to steadystate (1968-83) conditions. Simulated discharges from shallow-ground-water system in Nassau County were 10,700 Mgal/yr (million gallons per year) or 40,500,000 m3/yr (cubic meters per year), and those from Suffolk County were 52,300 Mgal/yr or 198,000,000 m3/yr. Discharges from deep-ground-water system in Nassau County were 4,900 Mgal/yr or 18,500,000 m3/yr, and those in Suffolk County were 12,700 Mgal/yr or 48,200,000 m3/yr.Ground-water concentrations of nitrogen decrease with depth and from west to east. The shallow ground water median nitrogen concentration for each county was determined using 1,155 samples collected at 167 shallow wells (125 feet deep or less) within 1 mile of the shore. The deep ground water median nitrate concentration (nitrate represented almost all of the total nitrogen) for each county was determined using 112 samples collected at 25 deep wells (greater than 125 feet deep) within 1 mile of the shore. The median nitrogen concentration for the shallow and median nitrate concentration for the deep ground water in Nassau County were 3.85 and 0.15 mg/L as N, during 1952–97; the corresponding concentrations for Suffolk County were 1.74 and <0.10 (less than 0.10) mg/L as N, during 1952–97.Nitrogen loads discharged from streams to the SSER for each year during 1972–97 were calculated as the annual total nitrogen concentration multiplied by the annual discharge. These values were calculated only for the seven streams for which sufficient data were available. The largest long-term (1972–97) average annual nitrogen load from Carlls River was 104 ton/yr or 94,300 kg/yr—about twice that of Connetquot River (54 ton/yr or 48,900 kg/yr) and over three times that of Carmans River (33 ton/yr or 29,900 kg/yr). The smallest annual mean nitrogen load was from Pines Brook, which has the lowest annual mean discharge of all streams analyzed.The nitrogen load carried to the SSER by ground-water discharge in shallow-ground-water system in Nassau and Suffolk Counties was calculated as the simulated discharge for each county multiplied by the respective median nitrogen concentration, and loads from deep-ground-water system were calculated as the simulated discharge for each county multiplied by the respective median nitrate concentration. All discharges were obtained from the U.S. Geological Survey's Long Island ground-water-flow model. The resultant nitrogen loads discharged to the SSER from shallow ground water were 172 ton/yr (156,000 kg/yr) from Nassau County and 380 ton/yr (345,000 kg/yr) from Suffolk County; equaling 552 ton/yr entering the SSER. Those from deep ground water were 3 ton/yr (2,700 kg/yr) from Nassau County and <0.5 ton/yr (480 kg/yr) from Suffolk County; equaling about 3.5 ton/yr entering the SSER.The sum of both stream loads and groundwater loads results in the total load to the SSER. The largest calculated total nitrogen load entering the SSER from both streams and ground water occurred in 1979 with a total load of 1,260 ton/yr (1,140,000 kg/yr). The smallest calculated nitrogen load entering the SSER occurred in 1995 with a total load of 725 ton/yr (658,000 kg/yr).

Methods of analysis by the U.S. Geological Survey National Water Quality Laboratory : evaluation of alkaline persulfate digestion as an alternative to Kjeldahl digestion for determination of total and dissolved nitrogen and phosphorus in water

USGS Publications Warehouse

Patton, Charles J.; Kryskalla, Jennifer R.

2003-01-01

Alkaline persulfate digestion was evaluated and validated as a more sensitive, accurate, and less toxic alternative to Kjeldahl digestion for routine determination of nitrogen and phosphorus in surface- and ground-water samples in a large-scale and geographically diverse study conducted by U.S. Geological Survey (USGS) between October 1, 2001, and September 30, 2002. Data for this study were obtained from about 2,100 surface- and ground-water samples that were analyzed for Kjeldahl nitrogen and Kjeldahl phosphorus in the course of routine operations at the USGS National Water Quality Laboratory (NWQL). These samples were analyzed independently for total nitrogen and total phosphorus using an alkaline persulfate digestion method developed by the NWQL Methods Research and Development Program. About half of these samples were collected during nominally high-flow (April-June) conditions and the other half were collected during nominally low-flow (August-September) conditions. The number of filtered and whole-water samples analyzed from each flow regime was about equal.By operational definition, Kjeldahl nitrogen (ammonium + organic nitrogen) and alkaline persulfate digestion total nitrogen (ammonium + nitrite + nitrate + organic nitrogen) are not equivalent. It was necessary, therefore, to reconcile this operational difference by subtracting nitrate + nitrite concentra-tions from alkaline persulfate dissolved and total nitrogen concentrations prior to graphical and statistical comparisons with dissolved and total Kjeldahl nitrogen concentrations. On the basis of two-population paired t-test statistics, the means of all nitrate-corrected alkaline persulfate nitrogen and Kjeldahl nitrogen concentrations (2,066 paired results) were significantly different from zero at the p = 0.05 level. Statistically, the means of Kjeldahl nitrogen concentrations were greater than those of nitrate-corrected alkaline persulfate nitrogen concentrations. Experimental evidence strongly suggests, however, that this apparent low bias resulted from nitrate interference in the Kjeldahl digestion method rather than low nitrogen recovery by the alkaline persulfate digestion method. Typically, differences between means of Kjeldahl nitrogen and nitrate-corrected alkaline persulfate nitrogen in low-nitrate concentration (< 0.1 milligram nitrate nitrogen per liter) subsets of filtered surface- and ground-water samples were statistically equivalent to zero at the p =level.Paired analytical results for dissolved and total phosphorus in Kjeldahl and alkaline persulfate digests were directly comparable because both digestion methods convert all forms of phosphorus in water samples to orthophosphate. On the basis of two-population paired t-test statistics, the means of all Kjeldahl phosphorus and alkaline persulfate phosphorus concentrations (2,093 paired results) were not significantly different from zero at the p = 0.05 level. For some subsets of these data, which were grouped according to water type and flow conditions at the time of sample collection, differences between means of Kjeldahl phosphorus and alkaline persulfate phosphorus concentrations were not equivalent to zero at the p = 0.05 level. Differences between means of these subsets, however, were less than the method detection limit for phosphorus (0.007 milligram phosphorus per liter) by the alkaline persulfate digestion method, and were therefore analytically insignificant.This report provides details of the alkaline persulfate digestion procedure, interference studies, recovery of various nitrogen- and phosphorus-containing compounds, and other analytical figures of merit. The automated air-segmented continuous flow methods developed to determine nitrate and orthophosphate in the alkaline persulfate digests also are described. About 125 microliters of digested sample are required to determine nitrogen and phosphorus in parallel at a rate of about 100 samples per hour with less than 1-percent sample in

Effects of Nitrogen Inputs and Watershed Characteristics on Summer Stream Nitrogen Concentrations: A National-Scale Analysis

EPA Science Inventory

Nitrogen (N) inputs to the landscape have been linked previously to N loads exported from watersheds at the national scale; however, stream N concentration is arguably more relevant than N load for drinking water quality, freshwater biological responses and establishment of nutri...

Evaluation of a Colorimetric Personal Dosimeter for Nitrogen Oxide.

ERIC Educational Resources Information Center

Diamond, Philip

A personal colorimetric dosimeter for nitrogen dioxide was developed. Tests were performed to determine the response of these strips to various concentrations of NO2. The dosimeter strips were satisfactory for approximate determinations of total exposure (concentration + time) of nitrogen dioxide. The total exposure was calculated in terms of time…

A modeling study examining the impact of nutrient boundaries ...

EPA Pesticide Factsheets

A mass balance eutrophication model, Gulf of Mexico Dissolved Oxygen Model (GoMDOM), has been developed and applied to describe nitrogen, phosphorus and primary production in the Louisiana shelf of the Gulf of Mexico. Features of this model include bi-directional boundary exchanges, an empirical site-specific light attenuation equation, estimates of 56 river loads and atmospheric loads. The model was calibrated for 2006 by comparing model output to observations in zones that represent different locations in the Gulf. The model exhibited reasonable skill in simulating the phosphorus and nitrogen field data and primary production observations. The model was applied to generate a nitrogen mass balance estimate, to perform sensitivity analysis to compare the importance of the nutrient boundary concentrations versus the river loads on nutrient concentrations and primary production within the shelf, and to provide insight into the relative importance of different limitation factors on primary production. The mass budget showed the importance of the rivers as the major external nitrogen source while the atmospheric load contributed approximately 2% of the total external load. Sensitivity analysis showed the importance of accurate estimates of boundary nitrogen concentrations on the nitrogen levels on the shelf, especially at regions further away from the river influences. The boundary nitrogen concentrations impacted primary production less than nitrogen concent

Effect of nitrogen sources on biomass, lipid and docosahexanoic acid production by Aurantiochytrium sp. SW1

NASA Astrophysics Data System (ADS)

Auma, Khairunnisa; Hamid, Aidil Abdul; Yusoff, Wan Mohtar Wan

2018-04-01

A local isolate, Aurantiochytrium sp. SW1 has been verified to have high content of docosahexanoic acid (DHA). However, the effect of different nitrogen sources on biomass, lipid concentration and DHA content in Aurantiochytrium sp. SW1 is still unknown. Hence, this study is focused in using six different organic and inorganic nitrogen sources to grow Aurantiochytrium sp. SW1 in optimized Burja medium. Monosodium glutamate (MSG) gave the highest biomass concentration of 15.97 g/L followed by ammonium nitrate (NH4NO3) with 13.37 g/L at 96 hr. These two nitrogen sources had significant effect on the biomass concentration (p<0.05). The highest lipid accumulated was obtained using MSG that reached 79.6% in biomass concentration. DHA content in lipid showed cultivation using MSG reached 47.9% (4.95 g/L). Statistical analysis using least significant difference (LSD) showed significant lipid production (p<0.05) when cultivated in MSG compared to other five nitrogen sources. The highest DHA productivity (0.052 g/L hr-1) was obtained in medium containing MSG. This study proves that nitrogen component in the medium significantly affects the biomass concentration, lipid and DHA content.

Real-time continuous nitrate monitoring in Illinois in 2013

USGS Publications Warehouse

Warner, Kelly L.; Terrio, Paul J.; Straub, Timothy D.; Roseboom, Donald; Johnson, Gary P.

2013-01-01

Many sources contribute to the nitrogen found in surface water in Illinois. Illinois is located in the most productive agricultural area in the country, and nitrogen fertilizer is commonly used to maximize corn production in this area. Additionally, septic/wastewater systems, industrial emissions, and lawn fertilizer are common sources of nitrogen in urban areas of Illinois. In agricultural areas, the use of fertilizer has increased grain production to meet the needs of a growing population, but also has resulted in increases in nitrogen concentrations in many streams and aquifers (Dubrovsky and others, 2010). The urban sources can increase nitrogen concentrations, too. The Federal limit for nitrate nitrogen in water that is safe to drink is 10 milligrams per liter (mg/L) (http://water.epa.gov/drink/contaminants/basicinformation/nitrate.cfm, accessed on May 24, 2013). In addition to the concern with nitrate nitrogen in drinking water, nitrogen, along with phosphorus, is an aquatic concern because it feeds the intensive growth of algae that are responsible for the hypoxic zone in the Gulf of Mexico. The largest nitrogen flux to the waters feeding the Gulf of Mexico is from Illinois (Alexander and others, 2008). Most studies of nitrogen in surface water and groundwater include samples for nitrate nitrogen collected weekly or monthly, but nitrate concentrations can change rapidly and these discrete samples may not capture rapid changes in nitrate concentrations that can affect human and aquatic health. Continuous monitoring for nitrate could inform scientists and water-resource managers of these changes and provide information on the transport of nitrate in surface water and groundwater.

Sagebrush and grasshopper responses to atmospheric carbon dioxide concentration.

PubMed

Johnson, R H; Lincoln, D E

1990-08-01

Seed- and clonally-propagated plants of Big Sagebrush (Artemisia tridentata var.tridentata) were grown under atmospheric carbon dioxide regimes of 270, 350 and 650 μl l -1 and fed toMelanoplus differentialis andM. sanguinipes grasshoppers. Total shrub biomass significantly increased as carbon dioxide levels increased, as did the weight and area of individual leaves. Plants grown from seed collected in a single population exhibited a 3-5 fold variation in the concentration of leaf volatile mono- and sesquiterpenes, guaianolide sesquiterpene lactones, coumarins and flavones within each CO 2 treatment. The concentration of leaf allelochemicals did not differ significantly among CO 2 treatments for these seed-propagated plants. Further, when genotypic variation was controlled by vegetative propagation, allelochemical concentrations also did not differ among carbon dioxide treatments. On the other hand, overall leaf nitrogen concentration declined significantly with elevated CO 2 . Carbon accumulation was seen to dilute leaf nitrogen as the balance of leaf carbon versus nitrogen progressively increased as CO 2 growth concentration increased. Grasshopper feeding was highest on sagebrush leaves grown under 270 and 650 μl l -1 CO 2 , but varied widely within treatments. Leaf nitrogen concentration was an important positive factor in grasshopper relative growth but had no overall effect on consumption. Potential compensatory consumption by these generalist grasshoppers was apparently limited by the sagebrush allelochemicals. Insects with a greater ability to feed on chemically defended host plants under carbon dioxide enrichment may ultimately consume leaves with a lower nitrogen concentration but the same concentration of allelochemicals. Compensatory feeding may potentially increase the amount of dietary allelochemicals ingested for each unit of nitrogen consumed.

The Nitrogen Cycle During the Transition to Euxinia

NASA Astrophysics Data System (ADS)

Meyer, K. M.; Kump, L. R.; Ridgwell, A.

2008-12-01

Nitrogen and phosphorous are essential to life, and their biological availability is hypothesized to regulate marine productivity on short and geologic timescales. The nature of primary production during recurrent intervals of Phanerozoic anoxia is of particular interest because of the redox control of nutrient and trace metal availability. Dissolved phosphate likely increased during transitions from oxic to euxinic marine conditions, while nitrogen availability may have decreased due to extensive denitrification as low-oxygen waters spread. Because nitrogen fixation is both metabolically and trace-metal intensive, a key question in the transition to euxinia is whether nitrogen fixation can "keep pace" with denitrification. If denitrification exceeds nitrogen fixation, diminished export production and oxygen demand in an N-limited ocean would pose a negative feedback that may prevent euxinia altogether or initiate the shift back to oxic conditions. Here we use the GENIE-1 Earth system model to address the biogeochemistry of the oxic-euxinic transition characteristic of some Phanerozoic oceanic anoxic events. As previously demonstrated with box models, phosphate accumulation stimulates both nitrogen fixation and denitrification. While there is an initial transient loss of total fixed nitrogen from the ocean, nitrogen inputs eventually exceed losses, and the marine nitrogen reservoir grows with that of phosphate to significantly exceed its modern value. Nitrogen buildup also corresponds with a shift in ecology of the surface ocean and the unexpected initiation of non-Redfieldian stoichiometry in the chemistry of the deep ocean.

An analytical study of nitrogen oxides and carbon monoxide emissions in hydrocarbon combustion with added nitrogen - Preliminary results

NASA Technical Reports Server (NTRS)

Bittker, D. A.

1980-01-01

The influence of ground-based gas turbine combustor operating conditions and fuel-bound nitrogen (FBN) found in coal-derived liquid fuels on the formation of nitrogen oxides and carbon monoxide is investigated. Analytical predictions of NOx and CO concentrations are obtained for a two-stage, adiabatic, perfectly-stirred reactor operating on a propane-air mixture, with primary equivalence ratios from 0.5 to 1.7, secondary equivalence ratios of 0.5 or 0.7, primary stage residence times from 12 to 20 msec, secondary stage residence times of 1, 2 and 3 msec and fuel nitrogen contents of 0.5, 1.0 and 2.0 wt %. Minimum nitrogen oxide but maximum carbon monoxide formation is obtained at primary zone equivalence ratios between 1.4 and 1.5, with percentage conversion of FBN to NOx decreasing with increased fuel nitrogen content. Additional secondary dilution is observed to reduce final pollutant concentrations, with NOx concentration independent of secondary residence time and CO decreasing with secondary residence time; primary zone residence time is not observed to affect final NOx and CO concentrations significantly. Finally, comparison of computed results with experimental values shows a good semiquantitative agreement.

Nitrogen Species in Soil, Sediment, and Ground Water at a Former Sewage-Treatment Wastewater Lagoon: Naval Air Station Whidbey Island, Island County, Washington

USGS Publications Warehouse

Cox, S.E.; Dinicola, R.S.; Huffman, R.L.

2007-01-01

The potential for contamination of ground water from remnant sewage sludge in re-graded sediments of a deconstructed sewage-treatment lagoon was evaluated. Ground-water levels were measured in temporary drive-point wells, and ground-water samples were collected and analyzed for nutrients and other water-quality characteristics. Composite soil and sediment samples were collected and analyzed for organic carbon and nitrogen species. Multiple lines of evidence, including lack of appreciable organic matter in sediments of the former lagoon, agronomic analysis of nitrogen, the sequestration of nitrogen in the developing soils at the former lagoon, and likely occurrence of peat deposits within the aquifer material, suggest that the potential for substantial additions of nitrogen to ground water beneath the former sewage lagoon resulting from remnant sewage sludge not removed from the former lagoon are small. Concentrations of nitrogen species measured in ground-water samples were small and did not exceed the established U.S. Environmental Protection Agency's maximum contaminant levels for nitrate (10 milligrams per liter). Concentrations of nitrate in ground-water samples were less than the laboratory reporting limit of 0.06 milligram per liter. Seventy to 90 percent of the total nitrogen present in ground water was in the ammonia form with a maximum concentration of 7.67 milligrams per liter. Concentrations of total nitrogen in ground water beneath the site, which is the sum of all forms of nitrogen including nitrate, nitrite, ammonia, and organic nitrogen, ranged from 1.15 to 8.44 milligrams per liter. Thus, even if all forms of nitrogen measured in ground water were converted to nitrate, the combined mass would be less than the maximum contaminant level. Oxidation-reduction conditions in ground water beneath the former sewage lagoon were reducing. Given the abundant supply of ambient organic carbon in the subsurface and in ground water at the former lagoon, any nitrate that may leach from residual sludge and be transported to ground water with recharge is expected to be quickly denitrified or transformed to nitrite and ammonia under the strongly reducing geochemical conditions that are present. Concentrations of organic carbon, the primary constituent of sewage sludge, in sediments of the former sewage lagoon were less than 1 percent, indicating a near absence of organic matter. The amount of total nitrogen present in the sediments at the former sewage lagoon was only about 25 percent of the amount typically present in developed agricultural soils. The lack of substantial carbon and nitrogen in sediments of the former sewage lagoon indicates that surficial sediments of the former lagoon are essentially devoid of residual sewage sludge. The largest concentration of total nitrogen measured in soil samples from the former sewage lagoon (330 milligrams per kilogram) was used to calculate an estimate of the amount of nitrogen that might be leached from residual sewage sludge by recharge. During the first two years following deconstruction of the former sewage lagoon, the concentration of total nitrogen in recharge leachate might exceed 10 milligrams per liter but the recharge leachate would not likely result in substantial increases in the nitrate concentration in ground water to concentrations greater than the drinking-water maximum contaminant level of 10 milligrams per liter.

A Mechanistic Investigation of Nitrogen Evolution and Corrosion with Oxy-Combustion

DOE Office of Scientific and Technical Information (OSTI.GOV)

Dale Tree; Andrew Mackrory; Thomas Fletcher

A premixed, staged, down-fired, pulverized coal reactor and a flat flame burner were used to study the evolution of nitrogen in coal contrasting differences in air and oxy-combustion. In the premixed reactor, the oxidizer was staged to produce a fuel rich zone followed by a burnout zone. The initial nominal fuel rich zone stoichiometric ratio (S.R.) of 0.85 selected produced higher NO reductions in the fuel rich region under oxy-combustion conditions. Air was found to be capable of similar NO reductions when the fuel rich zone was at a much lower S.R. of 0.65. At a S.R. of 0.85, oxy-combustionmore » was measured to have higher CO, unburned hydrocarbons, HCN and NH{sub 3} in the fuel rich region than air at the same S.R. There was no measured difference in the initial formation of NO. The data suggest devolatilization and initial NO formation is similar for the two oxidizers when flame temperatures are the same, but the higher CO{sub 2} leads to higher concentrations of CO and nitrogen reducing intermediates at a given equivalence ratio which increases the ability of the gas phase to reduce NO. These results are supported by flat flame burner experiments which show devolatilization of nitrogen from the coal and char to be similar for air and oxy-flame conditions at a given temperature. A model of premixed combustion containing devolatilization, char oxidation and detailed kinetics captures most of the trends seen in the data. The model suggests CO is high in oxy-combustion because of dissociation of CO{sub 2}. The model also predicts a fraction (up to 20%, dependent on S.R.) of NO in air combustion can be formed via thermal processes with the source being nitrogen from the air while in oxy-combustion equilibrium drives a reduction in NO of similar magnitude. The data confirm oxy-combustion is a superior oxidizer to air for NO control because NO reduction can be achieved at higher S.R. producing better char burnout in addition to NO from recirculated flue gas being reduced as it passes back through the flame.« less

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

NASA Astrophysics Data System (ADS)

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. The current increasing reactive N deposition will increase N export from the root zone, while it will only accelerate TOC and DON turnover if P availability is simultaneously increased. The Saharan dust-related Ca deposition has no impact on TOC and DON turnover.

Equilibrium and Balanced Growth of a Vegetative Crop

PubMed Central

SEGINER, IDO

2004-01-01

• Model A previously developed dynamic model, NICOLET, designed to predict growth and nitrate content of a lettuce crop, is subjected to (virtual) constant environmental conditions. For every combination of shoot and root environment, the cell sap, here assumed to reside in the ‘vacuole’ compartment, equilibrates at a certain nitrate concentration level. This, in turn, defines the composition of the crop in terms of carbon and nitrogen content in each of the three compartments of the model. Growth under constant environmental conditions is defined as ‘equilibrium’ growth (EG). If, in addition, the source strengths of carbon and nitrogen balance each other, as well as the sink strength of the growing crop, the growth is said to be ‘balanced’ (BG). • Results It is shown that the range of BG approximately coincides with the range of ‘mild’ nitrogen stress, where reduction in nitrogen availability results in a mild reduction of relative growth rate (RGR). Beyond a certain low nitrate concentration in the cell sap, the N‐stress becomes ‘severe’ and the loss of growth increases considerably. • Conclusions The model is able to mimic the five central observations of many constant‐environment growth‐chamber experiments, namely (1) the initial exponential growth and later decline of the RGR, (2) the constant chemical composition, (3) the equality of the RGR and the relative nutrient supply rate (RNR), (4) the proportionality between the N : C ratio and the RNR, and (5) the proportionality between the water content and the reduced N content. Guidelines for the optimal combination of the shoot and root environments are suggested. PMID:14681082

High nitrogen availability reduces polyphenol content in Sphagnum peat.

PubMed

Bragazza, Luca; Freeman, Chris

2007-05-15

Peat mosses of the genus Sphagnum constitute the bulk of living and dead biomass in bogs. These plants contain peculiar polyphenols which hamper litter peat decomposition through their inhibitory activity on microbial breakdown. In the light of the increasing availability of biologically active nitrogen in natural ecosystems, litter derived from Sphagnum mosses is an ideal substrate to test the potential effects of increased atmospheric nitrogen deposition on polyphenol content in litter peat. To this aim, we measured total nitrogen and soluble polyphenol concentration in Sphagnum litter peat collected in 11 European bogs under a chronic gradient of atmospheric nitrogen deposition. Our results demonstrate that increasing nitrogen concentration in Sphagnum litter, as a consequence of increased exogenous nitrogen availability, is accompanied by a decreasing concentration of polyphenols. This inverse relationship is consistent with reports that in Sphagnum mosses, polyphenol and protein biosynthesis compete for the same precursor. Our observation of modified Sphagnum litter chemistry under chronic nitrogen eutrophication has implications in the context of the global carbon balance, because a lower content of decay-inhibiting polyphenols would accelerate litter peat decomposition.

The effects of nitrogen pollutants on the isotopic signal (δ15N) of Ulva lactuca: Microcosm experiments.

PubMed

Orlandi, Lucia; Calizza, Edoardo; Careddu, Giulio; Carlino, Pasquale; Costantini, Maria Letizia; Rossi, Loreto

2017-02-15

Effects of two chemical forms of Nitrogen (NH 4 + and NO 3 - ) on δ 15 N in Ulva lactuca were analysed separately and in mixture at two concentrations. We assessed whether the δ 15 N values of U. lactuca discriminate between Nitrogen from synthetic fertilisers (inorganic) and from fresh cow manure (organic), and the isotopic ability of the macroalga to reflect Nitrogen concentrations. Isotopic signature and N content of the macroalga reflected different nitrogenous sources and their concentrations after 48h. The inorganic Nitrogen source (NH 4 NO 3 ) altered the isotopic values of the macroalgae more than Nitrogen from fresh cow manure (NO 3 - ). δ 15 N values observed in the mixed solution did not differ from those displayed in NH 4 NO 3 treatment alone. We conclude that stable isotope analysis of U. lactuca collected in an unpolluted site and experimentally submerged in sites suspected of being affected by disturbance is a useful tool for rapid monitoring of anthropogenic discharges of Nitrogen pollutants. Copyright © 2016 Elsevier Ltd. All rights reserved.

Nitrogen and Carbon Status Are Integrated at the Transcriptional Level by the Nitrogen Regulator NtrC In Vivo

PubMed Central

Schumacher, Jörg; Behrends, Volker; Pan, Zhensheng; Brown, Dan R.; Heydenreich, Franziska; Lewis, Matthew R.; Bennett, Mark H.; Razzaghi, Banafsheh; Komorowski, Michal; Barahona, Mauricio; Stumpf, Michael P. H.; Wigneshweraraj, Sivaramesh; Bundy, Jacob G.; Buck, Martin

2013-01-01

ABSTRACT Nitrogen regulation in Escherichia coli is a model system for gene regulation in bacteria. Growth on glutamine as a sole nitrogen source is assumed to be nitrogen limiting, inferred from slow growth and strong NtrB/NtrC-dependent gene activation. However, we show that under these conditions, the intracellular glutamine concentration is not limiting but 5.6-fold higher than in ammonium-replete conditions; in addition, α-ketoglutarate concentrations are elevated. We address this glutamine paradox from a systems perspective. We show that the dominant role of NtrC is to regulate glnA transcription and its own expression, indicating that the glutamine paradox is not due to NtrC-independent gene regulation. The absolute intracellular NtrC and GS concentrations reveal molecular control parameters, where NtrC-specific activities were highest in nitrogen-starved cells, while under glutamine growth, NtrC showed intermediate specific activity. We propose an in vivo model in which α-ketoglutarate can derepress nitrogen regulation despite nitrogen sufficiency. PMID:24255125

Freeze-drying of tert-butyl alcohol/water cosolvent systems: effects of formulation and process variables on residual solvents.

PubMed

Wittaya-Areekul, S; Nail, S L

1998-04-01

The objective of this study was to identify significant formulation and processing variables affecting levels of tert-butyl alcohol (TBA) and isopropyl alcohol (IPA) in freeze-dried solids prepared from TBA/water cosolvent systems. The variables examined were the physical state of the solute (crystalline vs amorphous), initial TBA concentration, freezing rate, cake thickness, and the temperature and duration of secondary drying. Sucrose and glycine were used as models for noncrystallizing and crystallizing solutes, respectively. The TBA concentration above which eutectic crystallization takes place was determined by differential scanning calorimetry. Model formulations were subjected to extremes of freezing rate by either dipping in liquid nitrogen or by slowly freezing on the shelf of a freeze-dryer. Dynamics of solvent loss during secondary drying was determined by withdrawing samples as a function of time at different shelf temperatures using a thief system. On the basis of these studies, the most important determinant of residual TBA level is the physical state of the solute. Freeze-dried glycine contained very low levels of residual TBA (0.01-0.03%) regardless of freezing rate or initial TBA concentration. For freeze-dried sucrose, residual TBA levels were approximately 2 orders of magnitude higher and were significantly affected by initial TBA concentration and freezing rate. For the sucrose/TBA/water system, relatively low residual TBA levels were obtained when the initial TBA level was above the threshold concentration for eutectic crystallization of TBA, whereas samples freeze-dried from solutions containing TBA concentrations below this threshold contained significantly higher levels of TBA. Residual IPA levels increased continuously with initial concentration of TBA in the sucrose/TBA/water system. Formulations of sucrose/TBA/water which were frozen rapidly contained residual TBA levels which were approximately twice those measured in the same formulation after slow freezing and drying under the same conditions. For the sucrose/TBA/water system, the temperature and time of secondary drying had only minimal influence on residual TBA in the freeze-dried solid. At low initial TBA concentrations (2%), residual TBA increases with increased cake thickness, perhaps because of the influence of depth of fill on effective freezing rate.

Accelerated aggregation of donor nitrogen in diamond containing NV centers

NASA Astrophysics Data System (ADS)

Lobanov, Sergey; Vins, Victor; Yelisseev, Alexander; Afonin, Dmitry; Blinkov, Alexander; Maximov, Yuriy

2010-05-01

The aggregation of donor nitrogen (C centers) into nitrogen pairs (A centers) is considered to be a second-order chemical reaction and the kinetics of this reaction can be written as follows: Kt = 1-- -1- Ct C0 where K is the aggregation rate constant that depends exponentially on temperature and activation energy K = Aexp (- Ea-kT ) and C0 and CT are C center concentrations before and after the aggregation. The activation energy Ea in natural diamonds is equal to 5±0.3 eV. However, it was shown by Vins (2004) that Ea varied in synthetic diamonds depending on Ni concentration from 3 to 6 eV; and in synthetic diamonds containing cobalt the activation energy exceeded 4 eV. The aggregation rate of C centers also increased dramatically in diamonds irradiated with high-energy electrons (Collins, 1980). An HPHT diamond single crystal grown in the Fe-Co-C system using the TGG method was studied. The initial C center concentration determined from the intensity of the 1130 cm-1 IR absorption band was equal to 118 ppm. In order to determine the influence of NV centers on the activation energy of aggregation, the crystal was at first irradiated with high-energy electrons (3MeV, 2×1018cm-2) and annealed in a quartz ampoule in vacuum (8000C, 2 hrs). This led to the formation of over 5 ppm of NV centers. After that the sample was annealed at high temperatures in the argon flow (15300C, 30 minutes). The IR absorption spectra revealed an

Nitrate Accumulation and Leaching in Surface and Ground Water Based on Simulated Rainfall Experiments

PubMed Central

Wang, Hong; Gao, Jian-en; Li, Xing-hua; Zhang, Shao-long; Wang, Hong-jie

2015-01-01

To evaluate the process of nitrate accumulation and leaching in surface and ground water, we conducted simulated rainfall experiments. The experiments were performed in areas of 5.3 m2 with bare slopes of 3° that were treated with two nitrogen fertilizer inputs, high (22.5 g/m2 NH4NO3) and control (no fertilizer), and subjected to 2 hours of rainfall, with. From the 1st to the 7th experiments, the same content of fertilizer mixed with soil was uniformly applied to the soil surface at 10 minutes before rainfall, and no fertilizer was applied for the 8th through 12th experiments. Initially, the time-series nitrate concentration in the surface flow quickly increased, and then it rapidly decreased and gradually stabilized at a low level during the fertilizer experiments. The nitrogen loss in the surface flow primarily occurred during the first 18.6 minutes of rainfall. For the continuous fertilizer experiments, the mean nitrate concentrations in the groundwater flow remained at less than 10 mg/L before the 5th experiment, and after the 7th experiment, these nitrate concentrations were greater than 10 mg/L throughout the process. The time-series process of the changing concentration in the groundwater flow exhibited the same parabolic trend for each fertilizer experiment. However, the time at which the nitrate concentration began to change lagged behind the start time of groundwater flow by approximately 0.94 hours on average. The experiments were also performed with no fertilizer. In these experiments, the mean nitrate concentration of groundwater initially increased continuously, and then, the process exhibited the same parabolic trend as the results of the fertilization experiments. The nitrate concentration decreased in the subsequent experiments. Eight days after the 12 rainfall experiments, 50.53% of the total nitrate applied remained in the experimental soil. Nitrate residues mainly existed at the surface and in the bottom soil layers, which represents a potentially more dangerous pollution scenario for surface and ground water. The surface and subsurface flow would enter into and contaminate water bodies, thus threatening the water environment. PMID:26291616

Nitrate Accumulation and Leaching in Surface and Ground Water Based on Simulated Rainfall Experiments.

PubMed

Wang, Hong; Gao, Jian-en; Li, Xing-hua; Zhang, Shao-long; Wang, Hong-jie

2015-01-01

To evaluate the process of nitrate accumulation and leaching in surface and ground water, we conducted simulated rainfall experiments. The experiments were performed in areas of 5.3 m2 with bare slopes of 3° that were treated with two nitrogen fertilizer inputs, high (22.5 g/m2 NH4NO3) and control (no fertilizer), and subjected to 2 hours of rainfall, with. From the 1st to the 7th experiments, the same content of fertilizer mixed with soil was uniformly applied to the soil surface at 10 minutes before rainfall, and no fertilizer was applied for the 8th through 12th experiments. Initially, the time-series nitrate concentration in the surface flow quickly increased, and then it rapidly decreased and gradually stabilized at a low level during the fertilizer experiments. The nitrogen loss in the surface flow primarily occurred during the first 18.6 minutes of rainfall. For the continuous fertilizer experiments, the mean nitrate concentrations in the groundwater flow remained at less than 10 mg/L before the 5th experiment, and after the 7th experiment, these nitrate concentrations were greater than 10 mg/L throughout the process. The time-series process of the changing concentration in the groundwater flow exhibited the same parabolic trend for each fertilizer experiment. However, the time at which the nitrate concentration began to change lagged behind the start time of groundwater flow by approximately 0.94 hours on average. The experiments were also performed with no fertilizer. In these experiments, the mean nitrate concentration of groundwater initially increased continuously, and then, the process exhibited the same parabolic trend as the results of the fertilization experiments. The nitrate concentration decreased in the subsequent experiments. Eight days after the 12 rainfall experiments, 50.53% of the total nitrate applied remained in the experimental soil. Nitrate residues mainly existed at the surface and in the bottom soil layers, which represents a potentially more dangerous pollution scenario for surface and ground water. The surface and subsurface flow would enter into and contaminate water bodies, thus threatening the water environment.

Biofilter for removal of nitrogen oxides from contaminated gases under aerobic conditions

DOEpatents

Apel, William A.

1998-01-01

A biofilter for reducing concentrations of gaseous nitrogen oxides in a polluted gas comprises a porous organic filter bed medium disposed in a housing, the filter bed medium including a mixed culture of naturally occurring denitrifying bacteria for converting the nitrogen oxides to nitrogen gas, carbon dioxide, and water. A method of reducing concentrations of nitrogen oxides in polluted gas comprises conducting the polluted gas through the biofilter so that the denitrifying bacteria can degrade the nitrogen oxides. A preferred filter medium is wood compost, however composts of other organic materials are functional. Regulation of pH, moisture content, exogenous carbon sources, and temperature are described.

Simultaneous removal of aniline, nitrogen and phosphorus in aniline-containing wastewater treatment by using sequencing batch reactor.

PubMed

Jiang, Yu; Wang, Hongyu; Shang, Yu; Yang, Kai

2016-05-01

The high removal efficiencies of traditional biological aniline-degrading systems always lead to accumulation of ammonium. In this study, simultaneous removal of aniline, nitrogen and phosphorus in a single sequencing batch reactor was achieved by using anaerobic/aerobic/anoxic (A/O/A) operational process. The removal efficiencies of COD, NH4(+)-N, TN, TP were over 95.80%, 83.03%, 87.13%, 90.95%, respectively in most cases with 250mgL(-1) of initial aniline at 6h cycle when DO was 5.5±0.5mgL(-1). Aniline was able to be completely degraded when initial concentrations were less than 750mgL(-1). When DO increased, the removal rate of NH4(+)-N and TP slightly increased along with the moderate decrease of removal efficiencies of TN. The variation of HRT had obvious influence on removal performance of pollutants. The system showed high removal efficiencies of aniline, COD and nutrients during the variation of operating conditions, which might contribute to disposal of aniline-rich industrial wastewater. Copyright © 2016 Elsevier Ltd. All rights reserved.

EFFECTS OF NITROGEN LOADING, FRESHWATER RESIDENCE TIME, AND INTERNAL LOSSES ON NITROGEN CONCENTRATIONS IN ESTUARIES

EPA Science Inventory

A simple model is presented that uses the annual loading rate of total nitrogen (TN) and the water residence time to calculate: 1) average annual TN concentration and intemalloss rates (e.g. denitrification and incorporation in sediments) in an estuary, and 2) the rate of nitroge...

Spatial and temporal variability of nitrate and nitrous oxide concentrations in the unsaturated zone at a corn field in the US Midwest

NASA Astrophysics Data System (ADS)

Gopalakrishnan, G.; Negri, C.

2011-12-01

There has been a significant increase in reactive nitrogen in the environment as a result of human activity. Reactive nitrogen of anthropogenic origin now equals that derived from natural terrestrial nitrogen fixation and is expected to exceed it by the end of the decade. Nitrogen is applied to crops as fertilizer and impacts the environment through water quality impairments (mostly as nitrate) and as greenhouse gas emissions (as nitrous oxide). Research on environmental impacts resulting from nitrogen application in the form of fertilizers has focused disproportionately on the degradation of water quality from agricultural non-point sources. The impacts of this degradation are registered both locally, with runoff and percolation of agrochemicals into local surface water and groundwater, and on a larger scale, such as the increase in the anoxic zone in the Gulf of Mexico attributed to nitrate from the Mississippi River. Impacts to the global climate from increased production of nitrous oxide as a result of increased fertilization are equally significant. Nitrous oxide is a greenhouse gas with a warming potential that is approximately 300 times greater than carbon dioxide. Direct emissions of nitrous oxide from the soil have been expressed as 1% of the applied nitrogen. Indirect emissions due to runoff, leaching and volatilization of the nitrogen from the field have been expressed as 0.75% of the applied nitrogen. Many studies have focused on processes governing nitrogen fluxes in the soil, surface water and groundwater systems. However, research on the biogeochemical processes regulating nitrogen fluxes in the unsaturated zone and consequent impacts on nitrate and nitrous oxide concentrations in groundwater are lacking. Our study explores the spatial and temporal variability of nitrate and nitrous oxide concentrations in the vadose zone at a 15 acre corn field in the US Midwest and links it to the concentrations found in the groundwater at the field site. Results indicated that nitrate concentrations in the vadose zone were an order of magnitude greater than in the groundwater. Nitrous oxide concentrations were significantly less in the vadose zone, suggesting that conditions for microbial degradation of the nitrate were not optimal. There was significant short-term variability in the nitrate concentrations as well as spatial variability over the field site. While the processes governing the linkage between nitrogen concentrations in the unsaturated and saturated zones are still unclear, our research suggests that current models may overestimate the indirect emissions of nitrous oxide produced in agricultural systems.

Development and Application of Regression Models for Estimating Nutrient Concentrations in Streams of the Conterminous United States, 1992-2001

USGS Publications Warehouse

Spahr, Norman E.; Mueller, David K.; Wolock, David M.; Hitt, Kerie J.; Gronberg, JoAnn M.

2010-01-01

Data collected for the U.S. Geological Survey National Water-Quality Assessment program from 1992-2001 were used to investigate the relations between nutrient concentrations and nutrient sources, hydrology, and basin characteristics. Regression models were developed to estimate annual flow-weighted concentrations of total nitrogen and total phosphorus using explanatory variables derived from currently available national ancillary data. Different total-nitrogen regression models were used for agricultural (25 percent or more of basin area classified as agricultural land use) and nonagricultural basins. Atmospheric, fertilizer, and manure inputs of nitrogen, percent sand in soil, subsurface drainage, overland flow, mean annual precipitation, and percent undeveloped area were significant variables in the agricultural basin total nitrogen model. Significant explanatory variables in the nonagricultural total nitrogen model were total nonpoint-source nitrogen input (sum of nitrogen from manure, fertilizer, and atmospheric deposition), population density, mean annual runoff, and percent base flow. The concentrations of nutrients derived from regression (CONDOR) models were applied to drainage basins associated with the U.S. Environmental Protection Agency (USEPA) River Reach File (RF1) to predict flow-weighted mean annual total nitrogen concentrations for the conterminous United States. The majority of stream miles in the Nation have predicted concentrations less than 5 milligrams per liter. Concentrations greater than 5 milligrams per liter were predicted for a broad area extending from Ohio to eastern Nebraska, areas spatially associated with greater application of fertilizer and manure. Probabilities that mean annual total-nitrogen concentrations exceed the USEPA regional nutrient criteria were determined by incorporating model prediction uncertainty. In all nutrient regions where criteria have been established, there is at least a 50 percent probability of exceeding the criteria in more than half of the stream miles. Dividing calibration sites into agricultural and nonagricultural groups did not improve the explanatory capability for total phosphorus models. The group of explanatory variables that yielded the lowest model error for mean annual total phosphorus concentrations includes phosphorus input from manure, population density, amounts of range land and forest land, percent sand in soil, and percent base flow. However, the large unexplained variability and associated model error precluded the use of the total phosphorus model for nationwide extrapolations.

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

PubMed

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 production across splanchnic organs when pigs are fed diets deficient in DAA nitrogen. © 2017 American Society for Nutrition.

Nitrogen and carbon flow from rock to water: Regulation through soil biogeochemical processes, Mokelumne River watershed, California, and Grand Valley, Colorado

USGS Publications Warehouse

Holloway, J.M.; Smith, R.L.

2005-01-01

Soil denitrification is an ecologically important nitrogen removal mechanism that releases to the atmosphere the greenhouse gas N2O, an intermediate product from the reduction of NO3- to N 2. In this study we evaluate the relationship between soil carbon and denitrification potential in watersheds with bedrock acting as a nonpoint source of nitrogen, testing the hypothesis that nitrate leaching to stream water is in part regulated by denitrification. Two sites, one in a Mediterranean climate and the other in an arid climate, were investigated to understand the interplay between carbon and denitrification potential. Both sites included carbonaceous bedrock with relatively high nitrogen concentrations (> 1,000 mg N kg-1) and had low background nitrogen concentrations in surface and groundwater. There was a net accumulation of carbon and nitrogen in soil relative to the corresponding bedrock, with the exception of carbonaceous shale from the arid site. There the concentration of carbon in the soil (15,620 mg C kg-1) was less than the shale parent (22,460 mg C kg-1), consistent with the bedrock being a source of soil carbon. Rates of denitrification potential (0.5-83 ??g N kg-1 hr-1) derived from laboratory incubations appeared to be related to the ratio of dissolved organic carbon and nitrate extracted from soils. These data indicate that microbial processes such as denitrification can help maintain background nitrogen concentrations to tens of ??M N in relatively undisturbed ecosystems when nitrogen inputs from weathering bedrock are accompanied by sufficient organic carbon concentrations to promote microbial nitrogen transformations.

[Key techniques for precision cultivation of nitrogenous fertilizer of pollution-free ginseng].

PubMed

Guo, Li-Li; Guo, Shuai; Dong, Lin-Lin; Shen, Liang; Li, Xi-Wen; Xu, Jiang; Chen, Shi-Lin

2018-04-01

Planting pollution-free farmland is the main mode of industrialization of ginseng cultivation, fine management of nitrogen fertilizer ginseng pollution-free farmland cultivation technology system is one of the key factors. In order to investigate the effect of nitrogenous fertilizer on the accumulation of ginseng biomass and saponins synthesis in vegetative growth stage, two-years-old ginsengs were used as test materials in this study. The test materials were cultivated by Hoagland medium with different nitrogen concentration (0，10，20，40 mg·L⁻¹) for 40 days. During the cultivation, photosynthetic rate was measured four times. After 40 days cultivation, chlorophyll content, stem diameter and the spatiotemporal expression of saponin synthesis related genes PgHMGR and PgSQE were tested. The results showed that there were significant differences in the photosynthetic rate and chlorophyll content among different nitrogen concentrations. The relative expression level of PgHMGR gene and PgSQE gene in root, stem and leaves of ginseng were different. Ginseng seedlings cultivated by 20 mg·L⁻¹ nitrogen possess the highest photosynthetic rate and chlorophyll content, while PgHMGR and PgSE showed the highest gene expression level. The optimal nitrogen concentration for the growth of 2-years-old ginseng might be 20 mg·L⁻¹ with 57.14 g ammonium nitrate each plant or pure 20.00 mg nitrogen each plant. It is concluded that this concentration is the most suitable concentration for the ginsenoside synthesis. Pollution-free ginseng with fine nitrogen fertilizer cultivation is conducive to the production of high quality and efficient ginseng medicinal materials. It lays a theoretical foundation for the rational fertilization and environment-friendly sustainable ecological ginseng planting industry. Copyright© by the Chinese Pharmaceutical Association.

An ab initio molecular dynamics study of thermal decomposition of 3,6-di(azido)-1,2,4,5-tetrazine.

PubMed

Wu, Qiong; Zhu, Weihua; Xiao, Heming

2014-10-21

Ab initio molecular dynamics simulations were performed to study the thermal decomposition of isolated and crystal 3,6-di(azido)-1,2,4,5-tetrazine (DiAT). During unimolecular decomposition, the three different initiation mechanisms were observed to be N-N2 cleavage, ring opening, and isomerization, respectively. The preferential initial decomposition step is the homolysis of the N-N2 bond in the azido group. The release mechanisms of nitrogen gas are found to be very different in the early and later decomposition stages of crystal DiAT. In the early decomposition, DiAT decomposes very fast and drastically without forming any stable long-chains or heterocyclic clusters, and most of the nitrogen gases are released through rapid rupture of nitrogen-nitrogen and carbon-nitrogen bonds. But in the later decomposition stage, the release of nitrogen gas is inhibited due to low mobility, long distance from each other, and strong carbon-nitrogen bonds. To overcome the obstacles, the nitrogen gases are released through slow formation and disintegration of polycyclic networks. Our simulations suggest a new decomposition mechanism for the organic polyazido initial explosive at the atomistic level.

Coniferous coverage as well as catchment steepness influences local stream nitrate concentrations within a nitrogen-saturated forest in central Japan.

PubMed

Watanabe, Mirai; Miura, Shingo; Hasegawa, Shun; Koshikawa, Masami K; Takamatsu, Takejiro; Kohzu, Ayato; Imai, Akio; Hayashi, Seiji

2018-04-28

High concentrations of nitrate have been detected in streams flowing from nitrogen-saturated forests; however, the spatial variations of nitrate leaching within those forests and its causes remain poorly explored. The aim of this study is to evaluate the influences of catchment topography and coniferous coverage on stream nitrate concentrations in a nitrogen-saturated forest. We measured nitrate concentrations in the baseflow of headwater streams at 40 montane forest catchments on Mount Tsukuba in central Japan, at three-month intervals for 1 year, and investigated their relationship with catchment topography and with coniferous coverage. Although stream nitrate concentrations varied from 0.5 to 3.0 mgN L -1 , those in 31 catchments consistently exceeded 1 mgN L -1 , indicating that this forest had experienced nitrogen saturation. A classification and regression tree analysis with multiple environmental factors showed that the mean slope gradient and coniferous coverage were the best and second best, respectively, at explaining inter-catchment variance of stream nitrate concentrations. This analysis suggested that the catchments with steep topography and high coniferous coverage tend to have high nitrate concentrations. Moreover, in the three-year observation period for five adjacent catchments, the two catchments with relatively higher coniferous coverage consistently had higher stream nitrate concentrations. Thus, the spatial variations in stream nitrate concentrations were primarily regulated by catchment steepness and, to a lesser extent, coniferous coverage in this nitrogen-saturated forest. Our results suggest that a decrease in coniferous coverage could potentially contribute to a reduction in nitrate leaching from this nitrogen-saturated forest, and consequently reduce the risk of nitrogen overload for the downstream ecosystems. This information will allow land managers and researchers to develop improved management plans for this and similar forests in Japan and elsewhere. Copyright © 2018 Elsevier B.V. All rights reserved.

Effects of nitrogen fertilization on the phenolic composition and antioxidant properties of basil (Ocimum basilicum L.).

PubMed

Nguyen, Phuong M; Niemeyer, Emily D

2008-09-24

Many herbs and spices have been shown to contain high levels of polyphenolic compounds with potent antioxidant properties. In the present study, we explore how nutrient availability, specifically nitrogen fertilization, affects the production of polyphenolic compounds in three cultivars (Dark Opal, Genovese, and Sweet Thai) of the culinary herb, basil ( Ocimum basilicum L.). Nitrogen fertilization was found to have a significant effect on total phenolic levels in Dark Opal ( p < 0.001) and Genovese ( p < 0.001) basil with statistically higher phenolic contents observed when nutrient availability was limited at the lowest (0.1 mM) applied nitrogen treatment. Similarly, basil treated at the lowest nitrogen fertilization level generally contained significantly higher rosmarinic ( p = 0.001) and caffeic ( p = 0.001) acid concentrations than basil treated at other nitrogen levels. Nitrogen fertilization also affected antioxidant activity ( p = 0.002) with basil treated at the highest applied nitrogen level, 5.0 mM, exhibiting lower antioxidant activity than all other nitrogen treatments. The anthocyanin content of Dark Opal basil was not affected by applied nitrogen level, but anthocyanin concentrations were significantly impacted by growing season ( p = 0.001). Basil cultivar was also determined to have a statistically significant effect on total phenolic levels, rosmarinic and caffeic acid concentrations, and antioxidant activities.

Application of Bacillus sp. TAT105 to reduce ammonia emissions during pilot-scale composting of swine manure.

PubMed

Kuroda, Kazutaka; Tanaka, Akihiro; Furuhashi, Kenich; Nakasaki, Kiyohiko

2017-12-01

Thermophilic ammonium-tolerant bacterium Bacillus sp. TAT105 grows and reduces ammonia (NH 3 ) emissions by assimilating ammonium nitrogen during composting of swine feces. To evaluate the efficacy of a biological additive containing TAT105 at reducing NH 3 emissions, composting tests of swine manure on a pilot scale (1.8 m 3 ) were conducted. In the TAT105-added treatment, NH 3 emissions and nitrogen loss were lower than those in the control treatment without TAT105. No significant difference was detected in losses in the weight and volatile solids between the treatments. Concentration of thermophilic ammonium-tolerant bacteria in the compost increased in both treatments at the initial stage of composting. In the TAT105-added treatment, bacterial concentration reached ~10 9 colony-forming units per gram of dry matter, several-fold higher than that in the control and stayed at the same level until the end. These results suggest that TAT105 grows during composting and reduces NH 3 emissions in TAT105-added treatment.

Optimization of hydrolysis and volatile fatty acids production from sugarcane filter cake: Effects of urea supplementation and sodium hydroxide pretreatment.

PubMed

Janke, Leandro; Leite, Athaydes; Batista, Karla; Weinrich, Sören; Sträuber, Heike; Nikolausz, Marcell; Nelles, Michael; Stinner, Walter

2016-01-01

Different methods for optimization the anaerobic digestion (AD) of sugarcane filter cake (FC) with a special focus on volatile fatty acids (VFA) production were studied. Sodium hydroxide (NaOH) pretreatment at different concentrations was investigated in batch experiments and the cumulative methane yields fitted to a dual-pool two-step model to provide an initial assessment on AD. The effects of nitrogen supplementation in form of urea and NaOH pretreatment for improved VFA production were evaluated in a semi-continuously operated reactor as well. The results indicated that higher NaOH concentrations during pretreatment accelerated the AD process and increased methane production in batch experiments. Nitrogen supplementation resulted in a VFA loss due to methane formation by buffering the pH value at nearly neutral conditions (∼ 6.7). However, the alkaline pretreatment with 6g NaOH/100g FCFM improved both the COD solubilization and the VFA yield by 37%, mainly consisted by n-butyric and acetic acids. Copyright © 2015 Elsevier Ltd. All rights reserved.

Utilization of Bacillus sp. strain TAT105 as a biological additive to reduce ammonia emissions during composting of swine feces.

PubMed

Kuroda, Kazutaka; Waki, Miyoko; Yasuda, Tomoko; Fukumoto, Yasuyuki; Tanaka, Akihiro; Nakasaki, Kiyohiko

2015-01-01

Bacillus sp. strain TAT105 is a thermophilic, ammonium-tolerant bacterium that grows assimilating ammonium nitrogen and reduces ammonia emission during composting of swine feces. To develop a practical use of TAT105, a dried solid culture of TAT105 (5.3 × 10(9) CFU/g of dry matter) was prepared as an additive. It could be stored for one year without significant reduction of TAT105. Laboratory-scale composting of swine feces was conducted by mixing the additive. When the additive, mixed with an equal weight of water one day before use, was added to obtain a TAT105 concentration of above 10(7) CFU/g of dry matter in the initial material, the ammonia concentration emitted was lower and nitrogen loss was approximately 22% lower in the treatment with the additive than in the control treatment without the additive. The colony formation on an agar medium containing high ammonium could be used for enumeration of TAT105 in the composted materials.

Enhanced nitrate-nitrogen removal by modified attapulgite-supported nanoscale zero-valent iron treating simulated groundwater.

PubMed

Dong, Lei; Lin, Li; Li, Qingyun; Huang, Zhuo; Tang, Xianqiang; Wu, Min; Li, Chao; Cao, Xiaohuan; Scholz, Miklas

2018-05-01

Attapulgite (or palygorskite) is a magnesium aluminium phyllosilicate. Modified attapulgite-supported nanoscale zero-valent iron (NZVI) was created by a liquid-phase reduction method and then applied for nitrate-nitrogen (NO 3 -N) removal (transformation) in simulated groundwater. Nanoscale zero-valent iron was sufficiently dispersed on the surface of thermally modified attapulgite. The NO 3 -N removal efficiency reached up to approximately 83.8% with an initial pH values of 7.0. The corresponding thermally modified attapulgite-supported nanoscale zero-valent iron (TATP-NZVI) and NO 3 -N concentrations were 2.0 g/L and 20 mg/L respectively. Moreover, 72.1% of the water column NO 3 -N was converted to ammonium-nitrogen (NH 4 -N) within 6 h. The influence of environmental boundary conditions including dissolved oxygen (DO) concentration, light illumination and water temperature on NO 3 -N removal was also investigated with batch experiments. The results indicated that the DO concentration greatly impacted on NO 3 -N removal in the TATP-NZVI-contained solution, and the NO 3 -N removal efficiencies were 58.5% and 83.3% with the corresponding DO concentrations of 9.0 and 0.3 mg/L after 6 h of treatment, respectively. Compared to DO concentrations, no significant (p > 0.05) effect of light illumination on NO 3 -N removal and NH 4 -N generation was detected. The water temperature also has great importance concerning NO 3 -N reduction, and the removal efficiency of NO 3 -N at 25 °C was 1.25 times than that at 15 °C. For groundwater, therefore, environmental factors such as water temperature, anaerobic conditions and darkness could influence the NO 3 -N removal efficiency when TATP-NZVI is present. This study also demonstrated that TATP-NZVI has the potential to be developed as a suitable material for direct remediation of NO 3 -N-contaminated groundwater. Copyright © 2018 Elsevier Ltd. All rights reserved.

A latitudinal gradient in seed nutrients of the forest herb Anemone nemorosa.

PubMed

De Frenne, P; Kolb, A; Graae, B J; Decocq, G; Baltora, S; De Schrijver, A; Brunet, J; Chabrerie, O; Cousins, S A O; Dhondt, R; Diekmann, M; Gruwez, R; Heinken, T; Hermy, M; Liira, J; Saguez, R; Shevtsova, A; Baskin, C C; Verheyen, K

2011-05-01

The nutrient concentration in seeds determines many aspects of potential success of the sexual reproductive phase of plants, including the seed predation probability, efficiency of seed dispersal and seedling performance. Despite considerable research interest in latitudinal gradients of foliar nutrients, a similar gradient for seeds remains unexplored. We investigated a potential latitudinal gradient in seed nutrient concentrations within the widespread European understorey forest herb Anemone nemorosa L. We sampled seeds of A. nemorosa in 15 populations along a 1900-km long latitudinal gradient at three to seven seed collection dates post-anthesis and investigated the relative effects of growing degree-hours >5 °C, soil characteristics and latitude on seed nutrient concentrations. Seed nitrogen, nitrogen:phosphorus ratio and calcium concentration decreased towards northern latitudes, while carbon:nitrogen ratios increased. When taking differences in growing degree-hours and measured soil characteristics into account and only considering the most mature seeds, the latitudinal decline remained particularly significant for seed nitrogen concentration. We argue that the decline in seed nitrogen concentration can be attributed to northward decreasing seed provisioning due to lower soil nitrogen availability or greater investment in clonal reproduction. This pattern may have large implications for the reproductive performance of this forest herb as the degree of seed provisioning ultimately co-determines seedling survival and reproductive success. © 2010 German Botanical Society and The Royal Botanical Society of the Netherlands.

Characterization and prediction of organic nitrogen biodegradability during anaerobic digestion: A bioaccessibility approach.

PubMed

Bareha, Y; Girault, R; Jimenez, J; Trémier, A

2018-04-26

Prediction of organic nitrogen mineralization into ammonium during anaerobic digestion is required for optimizing substitution of mineral fertilizer by digestates. The aim of this study was to understand organic nitrogen biodegradability and to investigate how it can be predicted from carbon biodegradability, and nitrogen bioaccessibility, respectively. Bioaccessibility was assessed using fractionation methods based on sequential extractions. Results showed that organic nitrogen was present in fractions whose bioaccessibility levels differed. Organic nitrogen and carbon biodegradability were also determined and compared. Results highlighted two groups of substrates: the first with an initial NH 4 + /TKN < 30%, whose carbon and nitrogen biodegradability are similar; the second with an initial NH 4 + /TKN > 30%, whose carbon and nitrogen biodegradability differ significantly. To enable prediction on all substrates, partial least square (PLS) regressions were carried out to link organic nitrogen bioaccessibility indicators to biodegradability. The models successfully predicted organic nitrogen biodegradability with a maximum prediction error of 10%. Copyright © 2018 Elsevier Ltd. All rights reserved.

Assessment of an apparent relationship between availability of soluble carbohydrates and reduced nitrogen during floral initiation in tobacco

NASA Technical Reports Server (NTRS)

Raper, C. D. Jr; Thomas, J. F.; Tolley-Henry, L.; Rideout, J. W.; Raper CD, J. r. (Principal Investigator)

1988-01-01

Daily relative accumulation rate of soluble carbohydrates (RARS) and reduced nitrogen (RARN) in the shoot, as estimates of source strength, were compared with daily relative growth rates (RGR) of the shoot, as an estimate of sink demand, during floral transformation in apical meristems of tobacco (Nicotiana tabacum 'NC 2326') grown at day/night temperatures of 18/14, 22/18, 26/22, 30/26, and 34/30 C. Source strength was assumed to exceed sink demand for either carbohydrates or nitrogen when the ratio of RARS/RGR or RARN/RGR was greater than unity, and sink demand was assumed to exceed source strength when the ratio was less than unity. Time of floral initiation, which was delayed up to 21 days with increases in temperature over the experimental range, was associated with intervals in which source strength of either carbohydrate or nitrogen exceeded sink demand, while sink demand for the other exceeded source strength. Floral initiation was not observed during intervals in which source strengths of both carbohydrates and nitrogen were greater than or less than sink demand. These results indicate that floral initiation is responsive to an imbalance in the relative availabilities of carbohydrate and nitrogen.

Free amino nitrogen concentration correlates to total yeast assimilable nitrogen concentration in apple juice.

PubMed

Boudreau, Thomas F; Peck, Gregory M; O'Keefe, Sean F; Stewart, Amanda C

2018-01-01

Yeast assimilable nitrogen (YAN) is essential for yeast growth and metabolism during apple ( Malus x domestica Borkh.) cider fermentation. YAN concentration and composition can impact cider fermentation kinetics and the formation of volatile aroma compounds by yeast. The YAN concentration and composition of apples grown in Virginia, USA over the course of two seasons was determined through analysis of both free amino nitrogen (FAN) and ammonium ion concentration. FAN was the largest fraction of YAN, with a mean value of 51 mg N L -1 FAN compared to 9 mg N L -1 ammonium. Observed YAN values ranged from nine to 249 mg N L -1 , with a mean value of 59 mg N L -1 . Ninety-four percent of all samples analyzed in this study contained <140 mg N L -1 YAN, a concentration generally considered the minimum level needed in grape-based wines for yeast to fully utilize all of the fermentable sugars. FAN concentration was correlated with total YAN concentration, but ammonium concentration was not. Likewise, there was no correlation between FAN and ammonium concentration.

Association of nitrogen compounds in drinking water with incidence of esophageal squamous cell carcinoma in Shexian, China.

PubMed

Zhang, Nan; Yu, Cao; Wen, Denggui; Chen, Jun; Ling, Yiwei; Terajima, Kenshi; Akazawa, Kohei; Shan, Baoen; Wang, Shijie

2012-01-01

The incidence of esophageal squamous cell carcinoma (ESCC), which is the eighth most common malignancy worldwide, is highest in China. The purpose of this study was to investigate the association between nitrogen compounds in drinking water with the incidence of ESCC by geographical spatial analysis. The incidence of ESCC is high in Shexian county, China, and environmental factors, particularly nitrogen-contaminated drinking water, are the main suspected risk factors. This study focuses on three nitrogen compounds in drinking water, namely, nitrates, nitrites, and ammonia, all of which are derived mainly from domestic garbage and agricultural fertilizer. The study surveyed 48 villages in the Shexian area with a total population of 54,716 (661 adults with ESCC and 54,055 non-cancer subjects). Hot-spot analysis was used to identify spatial clusters with a high incidence of ESCC and a high concentration of nitrogen compounds. Logistic regression analysis was used to detect risk factors for ESCC incidence. Most areas with high concentrations of nitrate nitrogen in drinking water had a high incidence of ESCC. Correlation analysis revealed a significant positive relationship between nitrate concentration and ESCC (P = 0.01). Logistic regression analysis also confirmed that nitrate nitrogen has a significantly higher odds ratio. The results indicate that nitrate nitrogen is associated with ESCC incidence in Shexian county. In conclusion, high concentrations of nitrate nitrogen in drinking water may be a significant risk factor for the incidence of ESCC.

[Effects of nitrogen deposition on the concentration and spectral characteristics of dissolved organic matter in soil solution in a young Cunninghamia lanceolata plantation.

PubMed

Yuan, Xiao Chun; Chen, Yue Min; Yuan, Shuo; Zheng, Wei; Si, You Tao; Yuan, Zhi Peng; Lin, Wei Sheng; Yang, Yu Sheng

2017-01-01

To study the effects of nitrogen deposition on the concentration and spectral characteristics of dissolved organic matter (DOM) in the forest soil solution from the subtropical Cunninghamia lanceolata plantation, using negative pressure sampling method, the dynamics of DOM in soil solutions from 0-15 and 15-30 cm soil layer was monitored for two years and the spectroscopic features of DOM were analyzed. The results showed that nitrogen deposition significantly reduced the concentration of dissolved organic carbon (DOC), and increased the aromatic index (AI) and the humic index (HIX), but had no significant effect on dissolved organic nitrogen (DON) concentration in both soil layers. There was obvious seasonal variation in DOM concentration of the soil solution, which was prominently higher in summer and autumn than in spring and winter.Fourier-transform infrared (FTIR) absorption spectrometry indicated that the DOM in forest soil solution had absorption peaks in the similar position of six regions, being the highest in wave number of 1145-1149 cm -1 . Three-dimensional fluorescence spectra indicated that DOM was mainly consisted of protein-like substances (Ex/Em=230 nm/300 nm) and microbial degradation products (Ex/Em=275 nm/300 nm). The availability of protein-like substances from 0-15 cm soil layer was reduced in the nitrogen treatments. Nitrogen deposition significantly reduced the concentration of DOC in soil solution, maybe largely by reducing soil pH, inhibiting soil carbon mineralization and stimulating plant growth. In particular, the decline of DOC concentration in the surface layer was due to the production inhibition of the protein-like substances and carboxylic acids. Short-term nitrogen deposition might be beneficial to the maintenance of soil fertility, while the long-term accumulation of nitrogen deposition might lead to the hard utilization of soil nutrients.

Surface-Enhanced Raman Scattering for Redox-Active Adsorbates: Pentaammineosmium(III)/(II) and Pentaammineruthenium(II) Containing Nitrogen Heterocycle Ligands.

DTIC Science & Technology

1984-04-01

Ill) and Os(Il) as determined using SERS are in good agreement with those obtained from rapid cyclic voltametry . The bulk-phase Raman spectra exhibit...under conventional conditions -i ( sweep rates ca. 100-500 mV sec ; reactant concentration ca. 1 ml_ for which the contribution from any initially...couple can also be obtained using cyclic voltammetry. -1 This entails using sufficiently rapid sweep rates (Z 20 V sec ) and small bulk reactant

[Monitoring and analysis on evolution process of rainfall runoff water quality in urban area].

PubMed

Dong, Wen; Li, Huai-En; Li, Jia-Ke

2013-02-01

In order to find the water quality evolution law and pollution characteristics of the rainfall runoff from undisturbed to the neighborhood exit, 6 times evolution process of rainfall runoff water quality were monitored and analyzed from July to October in 2011, and contrasted the clarification efficiency of the grassland to the roof runoff rudimentarily at the same time. The research showed: 1. the results of the comparison from "undisturbed, rainfall-roof, rainfall runoff-road, rainfall-runoff the neighborhood exit runoff " showed that the water quality of the undisturbed rain was better than that from the roof and the neighborhood exist, but the road rainfall runoff water quality was the worst; 2. the average concentrations of the parameters such as COD, ammonia nitrogen and total nitrogen all exceeded the Fifth Class of the Surface Water Quality Standard except for the soluble total phosphorus from undisturbed rainfall to the neighborhood exit; 3. the runoff water quality of the short early fine days was better than that of long early fine days, and the last runoff water quality was better than that of the initial runoff in the same rainfall process; 4. the concentration reduction of the grassland was notable, and the reduction rate of the grassland which is 1.0 meter wide of the roof runoff pollutants such as COD and nitrogen reached 30%.

[Interaction Between Sulfonamide Antibiotics Fates and Chicken Manure Composting].

PubMed

Lin, Hui; Wang, Jian-mei; Sun, Wan-chun; Fu, Jian-rong; Chen, Hong-jin; Ma, Jun-wei

2016-05-15

Based on aerobic manure composting with or without the addition of a mixture of sulfadimethoxine SM2 and sulfamonomethoxine SMM (1:1, m/m), changes in the physic-chemical properties of manure compost, the microbial community physiological profiles, the antibiotics concentration and the abundances of five antibiotic resistance genes (ARGs) during the composting were tracked. The results indicated that the introduction of sulfonamide antibiotics led to inhibition on the basal respiration of manure compost during the early composting period, delayed the formation of thermophilic temperature and reduced the conversion of nutrients such as organic matter, ammonia nitrogen and nitrate nitrogen. Meanwhile, the introduction of sulfonamide antibiotics dramatically affected the physiological profile of microbial community in manure in the middle stage of composting. HPLC-MS/MS results showed that both SMM and SM2 in manure were completely degraded within 14 days, while the degradation rate of SMM was faster than that of SM2. For both composting treatments with or without addition of exogenous antibiotics, the relative abundance of sull and sul2 showed an initial decline in the first 14 or 21 days and a slight increase thereafter. The addition of exogenous antibiotics showed insignificant enhancement on increasing the relative abundance of sul1 and IntI1 in manure, but resulted in an apparent increase in sul2 relative abundance. Although the fates of tetQ and tetW during composting were different from that of sulfonamide ARGs, the introduction of sulfonamide antibiotics into manure increased the relative abundance of tetracycline ARGs. Redundancy analysis indicated that composting temperature correlated negatively with sul1, sul2 and IntI1 relative abundance in manure but had no obvious relationship with tetQ and tetW relative abundance. All the ARGs detected in this work correlated negatively with C/N ratio and the nitrate nitrogen concentration of manure compost but positively correlated with pH, moisture and ammonia nitrogen concentration of manure compost.

Toward a mechanistic modeling of nitrogen limitation on vegetation dynamics.

PubMed

Xu, Chonggang; Fisher, Rosie; Wullschleger, Stan D; Wilson, Cathy J; Cai, Michael; McDowell, Nate G

2012-01-01

Nitrogen is a dominant regulator of vegetation dynamics, net primary production, and terrestrial carbon cycles; however, most ecosystem models use a rather simplistic relationship between leaf nitrogen content and photosynthetic capacity. Such an approach does not consider how patterns of nitrogen allocation may change with differences in light intensity, growing-season temperature and CO(2) concentration. To account for this known variability in nitrogen-photosynthesis relationships, we develop a mechanistic nitrogen allocation model based on a trade-off of nitrogen allocated between growth and storage, and an optimization of nitrogen allocated among light capture, electron transport, carboxylation, and respiration. The developed model is able to predict the acclimation of photosynthetic capacity to changes in CO(2) concentration, temperature, and radiation when evaluated against published data of V(c,max) (maximum carboxylation rate) and J(max) (maximum electron transport rate). A sensitivity analysis of the model for herbaceous plants, deciduous and evergreen trees implies that elevated CO(2) concentrations lead to lower allocation of nitrogen to carboxylation but higher allocation to storage. Higher growing-season temperatures cause lower allocation of nitrogen to carboxylation, due to higher nitrogen requirements for light capture pigments and for storage. Lower levels of radiation have a much stronger effect on allocation of nitrogen to carboxylation for herbaceous plants than for trees, resulting from higher nitrogen requirements for light capture for herbaceous plants. As far as we know, this is the first model of complete nitrogen allocation that simultaneously considers nitrogen allocation to light capture, electron transport, carboxylation, respiration and storage, and the responses of each to altered environmental conditions. We expect this model could potentially improve our confidence in simulations of carbon-nitrogen interactions and the vegetation feedbacks to climate in Earth system models.

Toward a Mechanistic Modeling of Nitrogen Limitation on Vegetation Dynamics

PubMed Central

Xu, Chonggang; Fisher, Rosie; Wullschleger, Stan D.; Wilson, Cathy J.; Cai, Michael; McDowell, Nate G.

2012-01-01

Nitrogen is a dominant regulator of vegetation dynamics, net primary production, and terrestrial carbon cycles; however, most ecosystem models use a rather simplistic relationship between leaf nitrogen content and photosynthetic capacity. Such an approach does not consider how patterns of nitrogen allocation may change with differences in light intensity, growing-season temperature and CO2 concentration. To account for this known variability in nitrogen-photosynthesis relationships, we develop a mechanistic nitrogen allocation model based on a trade-off of nitrogen allocated between growth and storage, and an optimization of nitrogen allocated among light capture, electron transport, carboxylation, and respiration. The developed model is able to predict the acclimation of photosynthetic capacity to changes in CO2 concentration, temperature, and radiation when evaluated against published data of Vc,max (maximum carboxylation rate) and Jmax (maximum electron transport rate). A sensitivity analysis of the model for herbaceous plants, deciduous and evergreen trees implies that elevated CO2 concentrations lead to lower allocation of nitrogen to carboxylation but higher allocation to storage. Higher growing-season temperatures cause lower allocation of nitrogen to carboxylation, due to higher nitrogen requirements for light capture pigments and for storage. Lower levels of radiation have a much stronger effect on allocation of nitrogen to carboxylation for herbaceous plants than for trees, resulting from higher nitrogen requirements for light capture for herbaceous plants. As far as we know, this is the first model of complete nitrogen allocation that simultaneously considers nitrogen allocation to light capture, electron transport, carboxylation, respiration and storage, and the responses of each to altered environmental conditions. We expect this model could potentially improve our confidence in simulations of carbon-nitrogen interactions and the vegetation feedbacks to climate in Earth system models. PMID:22649564

Reproductive effects on fecal nitrogen as an index of diet quality: an experimental assessment

USGS Publications Warehouse

Monteith, Kyle B.; Monteith, Kevin L.; Bowyer, R. Terry; Leslie,, David M.; Jenks, Jonathan A.

2014-01-01

Concentration of fecal nitrogen has been used widely as an indicator of dietary quality for free-ranging ruminants. Differences in digestive function between species of dimorphic ungulates render interspecific comparisons of fecal nitrogen unreliable; however, whether intraspecific sexual differences in digestive function also bias this nutritional index is unknown. Our objective was to compare sex-specific variation in concentration of fecal nitrogen using male, nonlactating female, and lactating female white-tailed deer (Odocoileus virginianus) on high- and low-quality diets. During weekly trials over spring and summer (2008-2009), we monitored intake rates, collected feces twice daily, and used micro-Kjeldahl procedures to determine percent fecal nitrogen. We also determined nitrogen content of feces following a neutral detergent fiber (NDF) rinse during pre-, peak, and postlactation. Fecal nitrogen reflected general differences in dietary quality between diets; however, fecal nitrogen of lactating females in both dietary groups was lower than for males or nonlactating females throughout lactation. Nitrogen concentration following an NDF rinse also was lower for lactating females during peak lactation. We hypothesize that the remodeling of the digestive tract and increased rumination by lactating females may enhance their ability to extract nitrogen from their forage. These adjustments may expand the foraging options of lactating females by increasing their ability to process low-quality foods, but also affects the interpretation of fecal nitrogen during the season of lactation.

A dynamic growth model of vegetative soya bean plants: model structure and behaviour under varying root temperature and nitrogen concentration

NASA Technical Reports Server (NTRS)

Lim, J. T.; Wilkerson, G. G.; Raper, C. D. Jr; Gold, H. J.

1990-01-01

A differential equation model of vegetative growth of the soya bean plant (Glycine max (L.) Merrill cv. Ransom') was developed to account for plant growth in a phytotron system under variation of root temperature and nitrogen concentration in nutrient solution. The model was tested by comparing model outputs with data from four different experiments. Model predictions agreed fairly well with measured plant performance over a wide range of root temperatures and over a range of nitrogen concentrations in nutrient solution between 0.5 and 10.0 mmol NO3- in the phytotron environment. Sensitivity analyses revealed that the model was most sensitive to changes in parameters relating to carbohydrate concentration in the plant and nitrogen uptake rate.

Impact of fermentation rate changes on potential hydrogen sulfide concentrations in wine.

PubMed

Butzke, Christian E; Park, Seung Kook

2011-05-01

The correlation between alcoholic fermentation rate, measured as carbon dioxide (CO2) evolution, and the rate of hydrogen sulfide (H2S) formation during wine production was investigated. Both rates and the resulting concentration peaks in fermentor headspace H2S were directly impacted by yeast assimilable nitrogenous compounds in the grape juice. A series of model fermentations was conducted in temperature-controlled and stirred fermentors using a complex model juice with defined concentrations of ammonium ions and/or amino acids. The fermentation rate was measured indirectly by noting the weight loss of the fermentor; H2S was quantitatively trapped in realtime using a pre-calibrated H2S detection tube which was inserted into a fermentor gas relief port. Evolution rates for CO2 and H2S as well as the relative ratios between them were calculated. These fermentations confirmed that total sulfide formation was strongly yeast strain-dependent, and high concentrations of yeast assimilable nitrogen did not necessarily protect against elevated H2S formation. High initial concentrations of ammonium ions via addition of diammonium phosphate (DAP) caused a higher evolution of H2S when compared with a non-supplemented but nondeficient juice. It was observed that the excess availability of a certain yeast assimilable amino acid, arginine, could result in a more sustained CO2 production rate throughout the wine fermentation. The contribution of yeast assimilable amino acids from conventional commercial yeast foods to lowering of the H2S formation was marginal.

Nutrients in Streams and Rivers Across the Nation -- 1992-2001

USGS Publications Warehouse

Mueller, David K.; Spahr, Norman E.

2006-01-01

Nutrient compounds of nitrogen and phosphorus were investigated in streams and rivers sampled as part of the U.S. Geological Survey National Water-Quality Assessment (NAWQA) Program. Nutrient data were collected in 20 NAWQA study units during 1992-95, 16 study units during 1996-98, and 15 study units during 1999-2001. To facilitate comparisons among sampling sites with variable sampling frequency, daily loads were determined by using regression models that relate constituent transport to streamflow and time. Model results were used to compute mean annual loads, yields, and concentrations of ammonia, nitrate, total nitrogen, orthophosphate, and total phosphorus, which were compared among stream and river sampling sites. Variations in the occurrence and distribution of nutrients in streams and rivers on a broad national scale reflect differences in the sources of nutrient inputs to the upstream watersheds and in watershed characteristics that affect movement of those nutrients. Sites were classified by watershed size and by land use in the upstream watershed: agriculture, urban, and undeveloped (forest or rangeland). Selection of NAWQA urban sites was intended to avoid effects of major wastewater-treatment plants and other point sources, but in some locations this was not feasible. Nutrient concentrations and yields generally increased with anthropogenic development in the watershed. Median concentrations and yields for all constituents at sites downstream from undeveloped areas were less than at sites downstream from agricultural or urban areas. Concentrations of ammonia, orthophosphate, and total phosphorus at agricultural and urban sites were not significantly different; however, concentrations of nitrate and total nitrogen were higher at agricultural than at urban sites. Total nitrogen concentrations at agricultural sites were higher in areas of high nitrogen input or enhanced transport, such as irrigation or artificial drainage that can rapidly move water from cropland to streams (Midwest, Northern Plains, and western areas of the United States). Concentrations were lower in the Southeast, where more denitrification occurs during transport of nitrogen compounds in shallow ground water. At urban sites, high concentrations of ammonia and orthophosphate were more prevalent downstream from wastewater-treatment plants. At sites with large watersheds and high mean-annual streamflow ('large-watershed' sites), concentrations of most nutrients were significantly less than at sites downstream from agricultural or urban areas. Total nitrogen concentrations at large-watershed sites were higher in Midwest agricultural areas and lower in the Western United States, where agricultural and urban development is less extensive. Total phosphorus concentrations at large-watershed sites were higher in areas of greater potential erosion and low overall runoff such as the arid areas in the West. Although not as distinct as seasonal patterns of streamflow, geographic patterns of seasonally high and low concentrations of total nitrogen and total phosphorus were identified in the data. Seasonal patterns in concentrations of total nitrogen generally mirror seasonal patterns in streamflow in the humid Eastern United States but are inverse to seasonal patterns in streamflow in the semiarid interior West. Total phosphorus concentrations typically have the opposite regional relation with streamflow; high concentrations coincide with high streamflows in the interior West. In the NAWQA Program, sites downstream from relatively undeveloped areas were selected to provide a baseline for comparison to sites with potential effects of urban development and agriculture. Concentrations of nitrate, total nitrogen, and total phosphorus at NAWQA undeveloped sites were found to be greater than values reported by other studies for conditions of essentially no development (background conditions). Concentrations at NAWQA undeveloped sites represent conditions

Nitrogen fertilisation increases biogenic amines and amino acid concentrations in Vitis vinifera var. Riesling musts and wines.

PubMed

Smit, Inga; Pfliehinger, Marco; Binner, Antonie; Großmann, Manfred; Horst, Walter J; Löhnertz, Otmar

2014-08-01

Wines rich in biogenic amines can cause adverse health effects to the consumer. Being nitrogen-containing substances, the amount of amines in wines might be strongly influenced by the rate of nitrogen fertiliser application during grape production. The aim of this work was to evaluate the effect of nitrogen fertilisation in the vineyard on the formation of biogenic amines in musts and wines. In a field experiment which compared unfertilised and fertilised (60 and 150 kg N ha(-1)) vines over two separate years, the total amine concentrations in must and wine increased. The latter was due to an increase of individual amines such as ethylamine, histamine, isopentylamine, phenylethylamine and spermidine in the musts and wines with the nitrogen application. Furthermore, the fermentation process increased the concentration of histamine and ethylamine in most of the treatments, while spermidine, spermine and isopentylamine concentrations generally decreased. Throughout both vintages, the concentrations of tyramine and histamine of the investigated musts and wines never reached detrimental levels to the health of non-allergenic people. Nitrogen fertilisation has a significant effect on amines formation in musts and wines. Furthermore, during fermentation, ethylamine and histamine increased while other amines were presumably serving as N sources during fermentation. © 2013 Society of Chemical Industry.

Application of a Two-Dimensional Reservoir Water-Quality Model of Beaver Lake, Arkansas, for the Evaluation of Simulated Changes in Input Water Quality, 2001-2003

USGS Publications Warehouse

Galloway, Joel M.; Green, W. Reed

2007-01-01

Beaver Lake is considered a primary watershed of concern in the State of Arkansas. As such, information is needed to assess water quality, especially nutrient enrichment, nutrient-algal relations, turbidity, and sediment issues within the system. A previously calibrated two-dimensional, laterally averaged model of hydrodynamics and water quality was used for the evaluation of changes in input nutrient and sediment concentrations on the water quality of the reservoir for the period of April 2001 to April 2003. Nitrogen and phosphorus concentrations were increased and decreased and tested independently and simultaneously to examine the nutrient concentrations and algal response in the reservoir. Suspended-solids concentrations were increased and decreased to identify how solids are distributed in the reservoir, which can contribute to decreased water clarity. The Beaver Lake model also was evaluated using a conservative tracer. A conservative tracer was applied at various locations in the reservoir model to observe the fate and transport and how the reservoir might react to the introduction of a conservative substance, or a worst-case spill scenario. In particular, tracer concentrations were evaluated at the locations of the four public water-supply intakes in Beaver Lake. Nutrient concentrations in Beaver Lake increased proportionally with increases in loads from the three main tributaries. An increase of 10 times the calibrated daily input nitrogen and phosphorus in the three main tributaries resulted in daily mean total nitrogen concentrations in the epilimnion that were nearly 4 times greater than the calibration concentrations at site L2 and more than 2 times greater than the calibrated concentrations at site L5. Increases in daily input nitrogen in the three main tributaries independently did not correspond in substantial increases in concentrations of nitrogen in Beaver Lake. The greatest proportional increase in phosphorus occurred in the epilimnion at sites L3 and L4 and the least increase occurred at sites L2 and L5 when calibrated daily input phosphorus concentrations were increased. When orthophosphorus was increased in all three tributaries simultaneously by a factor of 10, daily mean orthophosphorus concentrations in the epilimnion of the reservoir were almost 11 times greater than the calibrated concentrations at sites L2 and L5, and 15 times greater in the epilimnion of the reservoir at sites L3 and L4. Phosphorus concentrations in Beaver Lake increased less when nitrogen and phosphorus were increased simultaneously than when phosphorus was increased independently. The greatest simulated increase in algal biomass (represented as chlorophyll a) occurred when nitrogen and phosphorus were increased simultaneously in the three main tributaries. On average, the chlorophyll a values only increased less than 1 microgram per liter when concentrations of nitrogen or phosphorous were increased independently by a factor of 10 at all three tributaries. In comparison, when nitrogen and phosphorus were increased simultaneously by a factor of 10 for all three tributaries, the chlorophyll a concentration increased by about 10 micrograms per liter on average, with a maximum increase of about 57 micrograms per liter in the epilimnion at site L3 in Beaver Lake. Changes in algal biomass with changes in input nitrogen and phosphorus were variable through time in the Beaver Lake model from April 2001 to April 2003. When calibrated daily input nitrogen and phosphorus concentrations were increased simultaneously for the three main tributaries, the increase in chlorophyll a concentration was the greatest in late spring and summer of 2002. Changes in calibrated daily input inorganic suspended solids concentrations were examined because of the effect they may have on water clarity in Beaver Lake. The increase in total suspended solids was greatest in the hypolimnion at the upstream end of Beaver Lake, and negligible changes

Technical note: nitrogen fertilization effects on the degradation of aged diesel oil in composted drilling wastes.

PubMed

Choi, Woo-Jung; Chang, Scott X

2009-07-01

Hydrocarbon-contaminated wastes generated from oil and gas drilling activities may be used as a soil amendment once composted and further decomposition of residual hydrocarbons can be accomplished after the composts are applied to soils. To test if N fertilization may enhance hydrocarbon decomposition, we investigated the effects of N application on hydrocarbon degradation in different-aged composts (1-, 2-, 3-, and 4-year-old composts, coded as 1Y, 2Y, 3Y, and 4Y composts, respectively) through a pot experiment planted with white spruce (Picea glauca [Moench] Voss) seedlings. The percentage degradation of total petroleum hydrocarbon (TPH, C11 to C40) in the composts without N fertilization was correlated to initial NH4+ concentrations (R = 0.99, P < 0.001). The percentage degradation of TPH was highest in the 3Y compost (41.1%) that had an initial level of 325.3 mg NH4+ -N kg(-1) and the lowest in the IY compost (9.3%) that had an initial level of 8.3 mg NH4+ -N kg(-1). The degradation of TPH was enhanced by Nfertilization in the 1Y (from 9.3 to 15.3%) and 4Y composts (from 14.3 to 22.6%) that had low initial NH4+ concentrations. Our results show that application of NH4+ -based fertilizers may enhance the degradation of TPH when initial NH4+ concentrations in the compost are low.

Quantification of the contribution of nitrogen from septic tanks to ground water in Spanish Springs Valley, Nevada

USGS Publications Warehouse

Rosen, Michael R.; Kropf, Christian; Thomas, Karen A.

2006-01-01

Analysis of total dissolved nitrogen concentrations from soil water samples collected within the soil zone under septic tank leach fields in Spanish Springs Valley, Nevada, shows a median concentration of approximately 44 milligrams per liter (mg/L) from more than 300 measurements taken from four septic tank systems. Using two simple mass balance calculations, the concentration of total dissolved nitrogen potentially reaching the ground-water table ranges from 25 to 29 mg/L. This indicates that approximately 29 to 32 metric tons of nitrogen enters the aquifer every year from natural recharge and from the 2,070 houses that use septic tanks in the densely populated portion of Spanish Springs Valley. Natural recharge contributes only 0.25 metric tons because the total dissolved nitrogen concentration of natural recharge was estimated to be low (0.8 mg/L). Although there are many uncertainties in this estimate, the sensitivity of these uncertainties to the calculated load is relatively small, indicating that these values likely are accurate to within an order of magnitude. The nitrogen load calculation will be used as an input function for a ground-water flow and transport model that will be used to test management options for controlling nitrogen contamination in the basin.

Optimization of fertilization characteristics of urine by addition of Nitrosomonas europaea bio-seed.

PubMed

Hashemi, Shervin; Han, Mooyoung; Kim, Tschungil

2016-10-01

Because of the high concentration of nutrients in human urine, its utilization as an organic fertilizer has been notable throughout history. However, the nitrogen compounds in urine are not stable. Therefore, to convert urine into a suitable fertilizer, it is important to stabilize and adjust unstable nitrogen compounds such as ammonia. Because nitrification can influence the nitrogen profile, the use of nitrifying microorganisms can be useful for stabilizing the nitrogen profile of urine. This study investigated the changes in nitrogen compounds in pure urine and examined the effect of adding Nitrosomonas europaea bio-seed solution on these changes. It was found that the addition of bio-seed could reduce nitrogen loss as well as the time required to stabilize the nitrogen profile. Furthermore, the optimum concentration of bio-seed (6 × 10(5) N. europaea cells L(-1) ) that not only leads to the least nutrient loss but also results in an adequate nitrate/ammonium ratio and regulates the amount of nitrate produced, thereby preventing over-fertilization, was determined. At this concentration, no dilution or dewatering is required, thus minimizing water and energy consumption. Usage of the optimum of concentration of bio-seed will also eliminate the need for inorganic chemical additives. © 2016 Society of Chemical Industry. © 2016 Society of Chemical Industry.

Selected water-quality data for the Minidoka Irrigation District, south-central Idaho, June 1987

USGS Publications Warehouse

Young, H.W.; Parliman, D.J.; O'Dell, I.

1987-01-01

This map report presents June 1987 water-quality data, principally dissolved nitrite plus nitrate (as nitrogen), and depth-to-water measurements for 67 wells in the Minidoka Irrigation District, south-central Idaho. Nitrogen concentrations ranged from 0.2 to 76 milligrams per liter; the median concentrations was 6.6 milligrams per liter. Nitrogen concentrations in 9 samples exceeded the U. S. Environmental Protection Agency public drinking-water limit of 10 milligrams per liter. (USGS)

Degradation of sulfamethazine by gamma irradiation in the presence of hydrogen peroxide.

PubMed

Liu, Yuankun; Wang, Jianlong

2013-04-15

The gamma irradiation-induced degradation of sulfamethazine (SMT) in aqueous solution in the presence of hydrogen peroxide (H2O2) was investigated. The initial SMT concentration was 20mg/L and it was irradiated in the presence of extra H2O2 with initial concentration of 0, 10 and 30 mg/L. The results showed that gamma irradiation was effective for removing SMT in aqueous solution and its degradation conformed to the pseudo first-order kinetics under the applied conditions. When initial H2O2 concentration was in the range of 0-30 mg/L, higher concentration of H2O2 was more effective for the decomposition and mineralization of SMT. However, the removal of total organic carbon (TOC) was not as effective as that of SMT. Total nitrogen (TN) was not removed even at absorbed dose of 5 kGy, which was highest dose applied in this study. Major decomposition products of SMT, including degradation intermediates, organic acids and some inorganic ions were detected by high performance liquid chromatography (HPLC) and ion chromatography (IC). Sulfate (SO4(2-)), formic acid (HCOOH), acetic acid (CH3COOH), 4-aminophenol, 4-nitrophenol were identified in the irradiated solutions. Possible pathways for SMT decomposition by gamma irradiation in aqueous solution were proposed. Copyright © 2013 Elsevier B.V. All rights reserved.

[Kinetics of uptake of phosphates and nitrates by marine multicellular algae Gelidium latifolium (Grev.) Born. et Thur].

PubMed

Silkin, V A; Chubchikova, I N

2007-01-01

We studied nonstationary kinetics of the uptake of phosphates and nitrates by the red marine algae Gelidium latifolium (Grev.) Born et Thur. and calculated constants of the Michaelis-Menten equation for these elements. In the area of 0-3 microM, the kinetics of phosphate consumption had the following coefficients: maximum rate of uptake 0.8 micromol/(g x h), constant of half-saturation 1.745 microM. For nitrate nitrogen at 0-30 microM, an adaptive strategy of uptake kinetics was noted with change of the equation parameters with time: after 1 h, the maximum rate of uptake was 5.1 micromol/(g x h) and constant of half-saturation 19 gM, while within 2 h, the maximum rate of uptake significantly increased. This could be related to the synthesis of nitrate reductase. Coupled with the uptake of nitrates, nonstationary kinetics of the release of nitrates in the surrounding medium had a one-peak pattern: the maximum concentration of nitrites in the medium and the time of its achievement increased with the initial concentration of nitrates. The maximum concentration of nitrites was 6 to 14% of the initial concentration in the medium.

Removal of basic nitrogen compounds from hydrocarbon liquids

DOEpatents

Givens, Edwin N.; Hoover, David S.

1985-01-01

A method is provided for reducing the concentration of basic nitrogen compounds in hydrocarbonaceous feedstock fluids used in the refining industry by providing a solid particulate carbonaceous adsorbent/fuel material such as coal having active basic nitrogen complexing sites on the surface thereof and the coal with a hydrocarbonaceous feedstock containing basic nitrogen compounds to facilitate attraction of the basic nitrogen compounds to the complexing sites and the formation of complexes thereof on the surface of the coal. The adsorbent coal material and the complexes formed thereon are from the feedstock fluid to provide a hydrocarbonaceous fluid of reduced basic nitrogen compound concentration. The coal can then be used as fuel for boilers and the like.

Biofilter for removal of nitrogen oxides from contaminated gases under aerobic conditions

DOEpatents

Apel, W.A.

1998-08-18

A biofilter is described for reducing concentrations of gaseous nitrogen oxides in a polluted gas comprises a porous organic filter bed medium disposed in a housing, the filter bed medium including a mixed culture of naturally occurring denitrifying bacteria for converting the nitrogen oxides to nitrogen gas, carbon dioxide, and water. A method is described of reducing concentrations of nitrogen oxides in polluted gas comprises conducting the polluted gas through the biofilter so that the denitrifying bacteria can degrade the nitrogen oxides. A preferred filter medium is wood compost, however composts of other organic materials are functional. Regulation of pH, moisture content, exogenous carbon sources, and temperature are described. 6 figs.

Nitrogen dioxide and respiratory illness in children. Part II: Assessment of exposure to nitrogen dioxide.

PubMed

Lambert, W E; Samet, J M; Hunt, W C; Skipper, B J; Schwab, M; Spengler, J D

1993-06-01

Repeated measurements of nitrogen dioxide were obtained from 1988 to 1991 in the homes of 1,205 infants living in Albuquerque, NM. Passive diffusion samplers were used to obtain a series of two-week integrated measurements from the home of each infant for use in a cohort study of the relation of residential exposure to nitrogen dioxide and respiratory illnesses. Information on stove use and time spent inside the residence was collected at two-week and two-month intervals, respectively. During the winter, in the bedrooms of homes with gas cooking stoves, mean nitrogen dioxide concentrations were 21 parts per billion (ppb); mean concentrations in the living room and kitchen were 29 ppb and 34 ppb, respectively. In homes with electric cooking stoves, the mean bedroom concentration was 7 ppb during the winter. Lower indoor concentrations were observed during the summer in homes with both gas and electric stoves. On average, infants spent approximately 12.3 hours per day in their bedrooms, 7.3 hours in the living rooms, 35 minutes in the kitchens, and 3.8 hours out of their homes. (As a condition of participation, none of the infants spent more than 20 hours per week in day care outside of their homes). The mean time infants spent in the kitchen during cooking was approximately nine minutes per day. We tested whether exposures of infants living in homes with gas stoves could be reasonably estimated by measurements in the bedroom in comparison with time-weighted average concentrations based on time-activity data and simultaneous nitrogen dioxide measurements in the kitchen, living room, and bedroom. In 1,937 two-week intervals from 587 infants, 90% of time-weighted exposure (on the three-level classification used in this study) estimates were in agreement with estimates based on bedroom concentrations alone. The agreement of the time-weighted nitrogen dioxide exposure estimates with the bedroom concentrations is attributed to limited amounts of cooking stove use (the mean was 29 minutes per day), small room-to-room differences in nitrogen dioxide concentrations (the mean kitchen-bedroom difference was 12 ppb), and the relatively large proportion of time that infants spent in their bedrooms.

Photosynthesis-fermentation hybrid system to produce lipid feedstock for algal biofuel.

PubMed

Lu, Yue; Dai, Junbiao; Wu, Qingyu

2013-01-01

To avoid bacterial contamination due to medium replacement in the expanded application of a photosynthesis-fermentation model, an integrated photosynthesis-fermentation hybrid system was set up and evaluated for algal lipid production using Chlorella protothecoides. In this system, the CO2-rich off-gas from the fermentation process was recycled to agitate medium in thephotobioreactor, which could provide initial cells for the heterotrophic fermentation. The cell concentration reached 1.03 +/- 0.07 g/L during photoautotrophic growth and then the concentrated green cells were switched to heterotrophic fermentation after removing over 99.5% ofnitrogen in the medium by a nitrogen removal device. At the end offermentation in the system, the cell concentration could reach as high as 100.51 +/- 2.03 g/L, and 60.05 +/- 1.38% lipid content was achieved simultaneously. The lipid yield (60.36 +/- 2.63 g/L) in the hybrid system was over 700 times higher than that in a photobioreactor and exceeded that by fermentation alone (47.56 +/- 7.31 g/L). The developed photosynthesis-fermentation hybrid system in this study was not only a feasible option to enhance microalgal lipid production, but also an environment-friendly approach to produce biofuel feedstock through concurrent utilization of ammonia nitrogen, CO2, and organic carbons.

Remote sensing of canopy chemistry and nitrogen cycling in temperate forest ecosystems

NASA Technical Reports Server (NTRS)

Wessman, Carol A.; Aber, John D.; Peterson, David L.; Melillo, Jerry M.

1988-01-01

The use of images acquired by the Airborne Imaging Spectrometer, an experimental high-spectral resolution imaging sensor developed by NASA, to estimate the lignin concentration of whole forest canopies in Wisconsin is reported. The observed strong relationship between canopy lignin concentration and nitrogen availability in seven undisturbed forest ecosystems on Blackhawk Island, Wisconsin, suggests that canopy lignin may serve as an index for site nitrogen status. This predictive relationship presents the opportunity to estimate nitrogen-cycling rates across forested landscapes through remote sensing.

A nitrogen-doped graphene film prepared by chemical vapor deposition of a methanol mist containing methylated melamine resin

NASA Astrophysics Data System (ADS)

Mizuno, T.; Takizawa, M.; Tsuchiya, B.; Jinno, M.; Bandow, S.

2013-11-01

The effect of nitrogen doping on the sheet resistivity of a graphene film is systematically studied by changing the doping concentration. The nitrogen-doped graphene film is grown on a Cu foil by chemical vapor deposition using an ultrasonically generated methanol mist containing methylated melamine resin (simply called ‘melamine’). Using this method, it is found that the magnitude of the sheet resistivity is controllable by changing the melamine concentration. Increasing the melamine concentration up to ˜0.03 % causes a decrease of the sheet resistivity. We explain this by the substitutional doping of nitrogen atoms. A further increase in melamine concentration causes an increase of the sheet resistivity. This increase may be caused by the formation of pyridinic or pyrrolic N instead of substitutional N. Electron energy loss spectroscopy analyses for the carbon K-edge indicate a decrease of π ∗ character with increasing melamine concentration up to 0.08 % and then it recovers for higher concentration. This is due to a separation of the graphitic region and the defective region at high melamine concentration.

Onsite Wastewater System Nitrogen Contributions to Groundwater in Coastal North Carolina

PubMed Central

Humphrey, C.P.; O’Driscoll, M.A.; Deal, N.E.; Lindbo, D.L.; Thieme, S.C.; Zarate-Bermudez, M.A.

2016-01-01

The objective of the study described in this article was to evaluate the nitrogen contributions from two onsite wastewater systems (sites 1 and 2) to groundwater and adjacent surface waters in coastal Beaufort County, North Carolina. Groundwater levels and water quality parameters including total nitrogen, nitrogen species, temperature, and pH were monitored from October 2009 to May 2010. Nitrogen was also tested in groundwater from deeper irrigation or drinking water wells from the two sites and six additional neighboring residences. Mean total nitrogen concentrations in groundwater beneath onsite wastewater systems 1 and 2 were 34.3 ± 16.7 mg/L and 12.2 ± 2.9 mg/L, respectively, and significantly higher than background groundwater concentrations (<1 mg/L). Groundwater in the deeper wells appeared not to be influenced by the onsite systems. Groundwater nitrogen concentrations typically decreased with distance down-gradient from the systems, but were still elevated relative to background conditions more than 15 m from the systems and near the estuary. This was a pioneering effort to better understand the link of onsite systems, the fate of nitrogen in the environment, and public health. PMID:24437045

Nutrient Removal Vis-à-Vis Change in Partial Pressure of CO2 During Post-Monsoon Season in a Tropical Lentic and Lotic Aquatic Body: A Comparative Study

NASA Astrophysics Data System (ADS)

Bhattacharyya, Sourav; Chanda, Abhra; Das, Sourav; Akhand, Anirban; Pattanaik, Suchismita; Choudhury, S. B.; Dutta, Dibyendu; Hazra, Sugata

2018-04-01

The rate of nutrient removal and changes in pCO2 (water) were compared between a lentic aquaculture pond [East Kolkata Wetlands (EKW), India] and a lotic estuarine system [Diamond Harbor (DH) in Hugli Estuary, India] during the post-monsoon season (experiencing a similar tropical climate) by means of ex situ microcosm experiment. Though the DH waters were found to be substantial source of CO2 towards atmosphere and EKW waters to be sink for CO2 (according to the initial concentration of CO2), the eight consecutive days microcosm experiment revealed that the nutrient removal and pCO2 reduction efficiency were significantly higher in DH (ΔpCO2—90%) compared to EKW (ΔpCO2—78%). Among the five nutrients studied [dissolved nitrate-nitrogen (NO3-N), dissolved ammonium nitrogen (NH4-N), silicate, phosphate and iron], dissolved NO3-N followed by NH4-N was the most utilized in both EKW and DH. Except silicate, the other nutrients reduced to 78-91% in EKW and 84-99% in DH samples of their initial concentrations. Chlorophyll-a concentration steadily depleted in EKW ( 68-26 mg m-3) during the experiment indicating intense zooplankton grazing, whereas in DH it increased rapidly ( 3.4-23 mg m-3) with decreasing pCO2 (water). The present observations further indicated that regular flushing of EKW aquaculture ponds is required to avoid stagnation of water column which would enhance the zooplankton grazing and hamper the primary production of an otherwise sink of CO2. In DH, controlled freshwater discharge from Farakka and reduction of untreated organic waste might allow the existing phytoplankton community to enhance their photosynthetic activity.

[Effects of nitrogen addition and elevated CO2 concentration on soil dissolved organic carbon and nitrogen in rhizosphere and non-rhizosphere of Bothriochloa ischaemum].

PubMed

Xiao, Lie; Liu, Guo Bin; Li, Peng; Xue, Sha

2017-01-01

A pot experiment was conducted to study soil dissolved organic carbon (DOC) and dissolved organic nitrogen (DON) in the rhizosphere and non-rhizosphere of Bothriochloa ischaemum in loess hilly-gully region under the different treatments of CO 2 concentrations (400 and 800 μmol·mol -1 ) and nitrogen addition (0, 2.5, 5.0 g N·m -2 ·a -1 ). The results showed that eleva-ted CO 2 treatments had no significant effect on the contents of DOC, dissolved total nitrogen (DTN), DON, dissolved ammonium nitrogen (NH 4 + -N) and dissolved nitrate nitrogen (NO 3 - -N) in the soil of rhizosphere and non-rhizosphere of B. ischaemum. The contents of DTN, DON, and NO 3 - -N in the rhizosphere soil were significantly increased with the nitrogen application and the similar results of DTN and NO 3 - -N also were observed in the non-rhizosphere of B. ischaemum. Nitrogen application significantly decreased DOC/DON in the rhizosphere of B. ischaemum. The contents of DTN, NO 3 - -N and DON in the soil of rhizosphere were significantly lower than that in the non-rhizosphere soil, and DOC/DON was significantly higher in the rhizosphere soil than that in the non-rhizosphere soil. It indicated that short-term elevated CO 2 concentration had no significant influence on the contents of soil dissolved organic carbon and nitrogen. Simulated nitrogen deposition, to some extent, increased the content of soil dissolved nitrogen, but it was still insufficient to meet the demand of dissolved nitrogen for plant growing.

Nitrogen oxides from burning forest fuels examined by thermogravimetry and evolved gas analysis

Treesearch

H.B. Clements; Charles K. McMahon

1980-01-01

Abstract. Twelve forest fuels that varied widely in nitrogen content were burned in a thermogravimetric system, and nitrogen oxide production was analyzed by chemiluminescence. The effects of fuel nitrogen concentration, available oxygen, flow rate, and heating rate on nitrogen oxide production were examined.Results show that fuel nitrogen is an...

Oxidized Nitrogen in Precipitation, Throughfall, and Streamfall from a Forested Watershed in Oklahoma

USGS Publications Warehouse

Lawrence, Stephen J.; Wigington, Parker J.

1987-01-01

Oxidized nitrogen (nitrite plus nitrate N) concentrations were measured from bulk precipitation, bulk throughfall, and screamflow in a 7. 86 hectare forested watershed in southeastern Oklahoma during the wet season from March through June 1983. Oxidized nitrogen inputs comparable to results of other studies were recorded during the 19 rainstorms sampled. Oxidized nitrogen concentrations appeared to increase after rainfall interacted with the pine and hardwood canopies and were inversely related to both rainfall and throughfall depth. Oxidized N concentrations in streamflow were greatest during the rising limb of storm flow with subsequent decreases during the falling limb of storm hydrographs and lowest during base flow. The oxidized N inputs from bulk precipitation were considerably greater than outputs from streamflow resulting in a net retention of oxidized nitrogen within the watershed during the study period.

Physiological indicators of nitrogen response in short-rotation sycamore plantations. [Platanus occidentalis L

DOE Office of Scientific and Technical Information (OSTI.GOV)

Tschaplinski, T.J.; Norby, R.J.

1989-04-01

American sycamore (Platanus occidentalis L.) seedlings were grown in the field under urea-nitrogen fertilization regimes to identify physiological variables that characterize the growth responses. Treatments included trees fertilized at the beginning of the growing season with 450 kg N/ha, trees fertilized periodically (three times during the growing season) at 37.5 kg N/ha, and unfertilized controls. Above ground biomass accumulation in the heaviest nitrogen treatment was three times that of the controls, and nearly as much growth occurred when less nitrogen was added periodically. Photosynthesis, chlorophyll concentrations, and growth increased rapidly after a midseason application of a small amount of nitrogen,more » but not to a late-season application. There was no evidence that fertilization extended the physiologically active season or increased susceptibility to drought or cold. Sycamore leaves accumulated sucrose and mannose in response to water and cold stress in all treatments. Photosynthetic pigment concentrations, net photosynthetic rate, and leaf nitrate reductase activity were sensitive indicators of nitrogen fertilization, but foliar concentrations of nitrate, total nitrogen, soluble carbohydrate and soluble protein were not.« less

Trends in Streamflow and Nutrient and Suspended-Sediment Concentrations and Loads in the Upper Mississippi, Ohio, Red, and Great Lakes River Basins, 1975-2004

USGS Publications Warehouse

Lorenz, David L.; Robertson, Dale M.; Hall, David W.; Saad, David A.

2009-01-01

Many actions have been taken to reduce nutrient and suspended-sediment concentrations and the amount of nutrients and sediment transported in streams as a result of the Clean Water Act and subsequent regulations. This report assesses how nutrient and suspended-sediment concentrations and loads in selected streams have changed during recent years to determine if these actions have been successful. Flow-adjusted and overall trends in concentrations and trends in loads from 1993 to 2004 were computed for total nitrogen, dissolved ammonia, total organic nitrogen plus ammonia, dissolved nitrite plus nitrate, total phosphorus, dissolved phosphorus, total suspended material (total suspended solids or suspended sediment), and total suspended sediment for 49 sites in the Upper Mississippi, Ohio, Red, and Great Lakes Basins. Changes in total nitrogen, total phosphorus, and total suspended-material loads were examined from 1975 to 2003 at six sites to provide a longer term context for the data examined from 1993 to 2004. Flow-adjusted trends in total nitrogen concentrations at 19 of 24 sites showed tendency toward increasing concentrations, and overall trends in total nitrogen concentrations at 16 of the 24 sites showed a general tendency toward increasing concentrations. The trends in these flow-adjusted total nitrogen concentrations are related to the changes in fertilizer nitrogen applications. Flow-adjusted trends in dissolved ammonia concentrations from 1993 to 2004 showed a widespread tendency toward decreasing concentrations. The widespread, downward trends in dissolved ammonia concentrations indicate that some of the ammonia reduction goals of the Clean Water Act are being met. Flow-adjusted and overall trends in total organic plus ammonia nitrogen concentrations from 1993 to 2004 did not show a distinct spatial pattern. Flow-adjusted and overall trends in dissolved nitrite plus nitrate concentrations from 1993 to 2004 also did not show a distinct spatial pattern. Flow-adjusted trends in total phosphorus concentrations were upward at 24 of 40 sites. Overall trends in total phosphorus concentrations were mixed and showed no spatial pattern. Flow-adjusted and overall trends in dissolved phosphorus concentrations were consistently downward at all of the sites in the eastern part of the basins studied. The reduction in phosphorus fertilizer use and manure production east of the Mississippi River could explain most of the observed trends in dissolved phosphorus. Flow-adjusted trends in total suspended-material concentrations showed distinct spatial patterns of increasing tendencies throughout the western part of the basins studied and in Illinois and decreasing concentrations throughout most of Wisconsin, Iowa, and in the eastern part of the basins studied. Flow-adjusted trends in total phosphorus were strongly related to the flow-adjusted trends in suspended materials. The trends in the flow-adjusted suspended-sediment concentrations from 1993 to 2004 resembled those for suspended materials. The long-term, nonmonotonic trends in total nitrogen, total phosphorus, and suspended-material loads for 1975 to 2003 were described by local regression, LOESS, smoothing for six sites. The statistical significance of those trends cannot be determined; however, the long-term changes found for annual streamflow and load data indicate that the monotonic trends from 1993 to 2004 should not be extrapolated backward in time.

Sequestration of organic nitrogen in a paddy soil chronosequence as assessed by amino sugars molecular markers

NASA Astrophysics Data System (ADS)

Roth, Philipp; Lehndorff, E.; Cao, Z.; Amelung, W.

2010-05-01

Available nitrogen is a limiting factor in paddy rice systems due to ammonia volatilization, denitrification and stabilization in organic complexes. Soil organic nitrogen (SON) might therefore constitute a critical component of the nitrogen cycle in rice systems. The objective of this study was to elucidate the role of microorganisms for the sequestration of paddy N in organic forms. For this purpose we analyzed amino sugars as markers for the residues of bacteria and fungi in a chronosequence of soils that were used for paddy rice production for a period of 0 to 2000 years in the Hangzhou bay area in Southeast China. Within the soil profile, amino sugar concentrations were generally highest in the puddled Ap horizon and decreased with increasing depth along with organic carbon concentrations regardless of the time of rice cultivation. Nevertheless, a sharp increase of total amino sugar concentration from 0.1 g kg-1 to 0.3 g kg-1 was observed in the Ah horizon when comparing tidal wetland to salt marsh that had been impoldered 30 years ago, indicating an increasing importance of microbial residues in SON stabilization following the conversion of the semiaquatic marsh to a terrestrial system. With increased time of paddy rice cropping, amino sugar concentrations continued to increase up to a maximum of 2.1 g kg-1 after 300 years of paddy cultivation but declined again to 1 g kg-1 in soils with 700-2000 years history of cultivation despite increasing organic matter accumulation. Changes in the composition of the amino sugars were also most pronounced at initial stages of paddy rice management. The proportions of glucosamine (abundant in fungal chitin) decreased during the first 50 years of cultivation relative to mainly galactosamine (abundant in bacterial gums) and muramic acid (abundant in bacterial peptidoglycan), that remained at constantly low levels. At later stages of paddy rice cultivation, the ratios of glucosamine to galactosamine and to muramic acid re-increased. We conclude that microorganisms significantly contribute to the sequestration of paddy N in organic forms during the first 300 years of cropping, within an increasing contribution of bacteria as cropping time proceeds. At even longer periods of paddy rice cultivation, there appears to be a backshift to lower concentrations of microbial residues with higher proportions of fungal N remaining.

[Effects of slopes on nitrogen transport along with runoff from sloping plots on a lateritic red soil amended with sewage sludge].

PubMed

Chen, Yan-Hui; Chen, Ming-Hua; Wang, Guo; Chen, Wen-Xiang; Yang, Shun-Cheng; Chai, Peng

2010-10-01

The effects of different slopes on nitrogen transport along with runoff from sloping plots amended with sewage sludge on a lateritic red soil were studied under simulated rainfall conditions. When the sludge was broadcasted and mixed with surface soils (BM), the MTN (total nitrogen of mixing sample), STN (total nitrogen of settled sample), TPN (total particulate nitrogen), TSN (total suspended nitrogen), TDN (total dissolved nitrogen) and NH4(+) -N concentrations and nitrogen loss amounts in runoff of all treatments were highest at 1 day or 18 days after application. The highest concentrations and the loss amounts of MTN and STN in the slope runoff for the BM treatment increased with slope degree, showing increasing pollution risks to the surface waters. The STN concentration and loss amounts from the 25 degrees plots were 126.1 mg x L(-1) and 1788.6 mg x m(-2), respectively, being 4.6 times and 5.8 times of the corresponding values from the 10 degrees plots, respectively. Then the concentrations and the loss amounts of nitrogen (except NO3(-) -N) from the BM plots diminished rapidly first and then tended to be stable with dwindling differences between the slopes. The loss of MTN and STN in early runoff (1 day and 18 days) accounted for 68.6% -73.4% and 62.3% -66.7% of the cumulative loss amounts during the experimental period for all the broadcasted treatments. Runoff loss coefficients of MTN increased in the order of 20 degrees > 25 degrees > 15 degrees > 10 degrees. Nitrogen was largely lost in dissolved species while large portion of NH4(+) -N was lost with particulates.

Sonochemical degradation of ofloxacin in aqueous solutions.

PubMed

Hapeshi, E; Achilleos, A; Papaioannou, A; Valanidou, L; Xekoukoulotakis, N P; Mantzavinos, D; Fatta-Kassinos, D

2010-01-01

The use of low frequency (20 kHz), high energy ultrasound for the degradation of the antibiotic ofloxacin in water was investigated. Experiments were performed with a horn-type ultrasound generator at varying applied power densities (130-640 W/L), drug concentrations (5-20 mg/L), hydrogen peroxide concentrations (0-100 mM) and sparging gases (air, oxygen, nitrogen and argon). In general, conversion (which was assessed following sample absorbance at 288 nm) increased with increasing ultrasound energy and peroxide concentration and decreasing initial drug concentration. Moreover, reactions under an argon atmosphere were faster than with diatomic gases, possibly due to argon's physical properties (e.g. solubility, thermal conductivity and specific heat ratio) favoring sonochemical activity. Overall, low to moderate levels of ofloxacin degradation were achieved (i.e. it never exceeded 50%), thus indicating that radical reactions in the liquid bulk rather than thermal reactions in the vicinity of the cavitation bubble are responsible for ofloxacin degradation.

Adsorption of octylamine on titanium dioxide

NASA Astrophysics Data System (ADS)

Siwińska, Daria; Kołodziejczak-Radzimska, Agnieszka; Krysztafkiewicz, Andrzej; Jesionowski, Teofil

2009-05-01

Processes of adsorption and desorption of a model active substance (octylamine) on the surface of unmodified titanium dioxide (E 171) have been performed. The effects of concentration of octylamine and time of the process on the character of adsorption have been studied and the efficiency of the adsorption/desorption has been determined. The samples obtained have been studied by X-ray diffraction. The nitrogen adsorption/desorption isotherms, particle size distribution and absorption capacities of water, dibutyl phthalate and paraffin oil have been determined. The efficiency of octylamine adsorption on the surface of the titanium dioxide has been found positively correlated with the concentration of octylamine in the initial solution. The desorption of octylamine has decreased with increasing concentration of this compound adsorbed. For octylamine in low concentrations the physical adsorption has been found to dominate, which is desirable when using TiO 2 in the production of pharmaceuticals.

Making C4 crops more water efficient under current and future climate: Tradeoffs between carbon gain and water loss

NASA Astrophysics Data System (ADS)

Srinivasan, V.; Pignon, C.

2017-12-01

C4 plants have a carbon concentrating mechanism that has evolved under historically low CO2 concentrations of around 200 ppm. However, increases in global CO2 concentrations in recent times (current CO2 concentrations are at 400 ppm and it is projected to be 550 ppm by mid-century) have diminished the relative advantage of C4 plants over C3 plants, which lack the expensive carbon concentrating machinery. Here we show by employing model simulations that under pre-historic CO2 concentrations, C4 plants are near optimal in their stomatal behavior and nitrogen partitioning between carbon concentrating machinery and carboxylation machinery, and they are significantly supra-optimal under current and future elevated CO2 concentrations. Model simulations performed at current CO2 concentrations of 400 ppm show that, under high light conditions, decreasing stomatal conductance by 20% results in a 15% increase in water use efficiency with negligible loss in photosynthesis. Under future elevated CO2 concentrations of 550 ppm, a 40% decrease in stomatal conductance produces a 35% increase in water use efficiency. Furthermore, stomatal closure is shown to be more effective in decreasing whole canopy transpiration compared to canopy top leaf transpiration, since shaded leaves are more supra-optimal than sunlit leaves. Model simulations for optimizing nitrogen distribution in C4 leaves show that under high light conditions, C4 plants over invest in carbon concentrating machinery and under invest in carboxylation machinery. A 20% redistribution in leaf nitrogen results in a 10% increase in leaf carbon assimilation without significant increases in transpiration under current CO2 concentrations of 400 ppm. Similarly, a 40% redistribution in leaf nitrogen results in a 15% increase in leaf carbon assimilation without significant increases in transpiration under future elevated CO2 concentrations of 550 ppm. Our model optimality simulations show that C4 leaves a supra optimal in their stomatal behavior and leaf nitrogen distribution and by decreasing stomatal conductance and redistributing nitrogen away from carbon concentrating mechanism and towards carboxylation machinery, we can significantly decrease transpiration and increase carbon assimilation thereby increasing water use efficiency.

Trends in stream nitrogen concentrations for forested reference catchments across the USA

Treesearch

A. Argerich; S.L. Johnson; S.D. Sebestyen; C.C. Rhoades; E. Greathouse; J.D. Knoepp; M.B. Adams; G.E. Likens; J.L. Campbell; W.H. McDowell; F.N. Scatena; G.G. Ice

2013-01-01

To examine whether stream nitrogen concentrations in forested reference catchments have changed over time and if patterns were consistent across the USA, we synthesized up to 44 yr of data collected from 22 catchments at seven USDA Forest Service Experimental Forests. Trends in stream nitrogen presented high spatial variability both among catchments at a site and among...

Boreal ditched forest and peatland are more vulnerable to forest fire than unditched areas

NASA Astrophysics Data System (ADS)

Köhler, Stephan J.; Granath, Gustav; Landahl, Anna; Fölster, Jens

2016-04-01

During summer of 2014 the largest wildfire in Swedish modern history occurred. The fire was ignited in a forest close to the Swedish town Sala and incinerated a total of 14 000 ha. The frequency of wildfires is expected to increase, due to effects of climate change such as increased temperature and decreased precipitation during the summer months. Wildfires can have a considerable impact on aquatic ecosystems and previous studies of wildfires have shown elevated concentrations of nutrients, cat- and anions. The area of the fire mainly consists of forestland, peatland and lakes and has been affected by acidification and intensive forestry. To assess the fire severity and the effects on the water chemistry, the fire severity were analyzed and classified using aerial phtographs and high resolution LIDAR data. The analysis indicated that increased fire intensity caused increased fire severity and that drained forested areas were more vulnerable to fire than undrained peatland. Measurements of water chemistry were conducted at nine streams and ten lakes inside the affected area. At two sites sensors for multiple parameters were deployed. During the initial three months of the post-fire period large peaks of ammonia-N and sulphate were observed in the streams and in a majority of the lakes while DOC was suppressed. In one stream Gärsjöbäcken the median concentrations of ammonia-N were 79 times higher after the fire. Due to nitrification the elevated concentrations of ammonia-N-nitrogen caused elevated concentrations of nitrate-nitrogen. The initial peak of sulphate caused a drop in ANC but after the peak had past ANC increased due to elevated concentrations of base cations. Correlation analysis of fire severity and water chemistry indicated that the maximum concentrations of ammonia-N increased with severely burned canopies in drained forested peatlands and in scorched open peatland. In a future climate with increased dry spells extensive ditching operations in forested peatlands might be counterproductive as it promotes fire vulnerability even in cold boreal regions.

Variation characteristics of nitrogen concentrations through forest hydrologic subcycles in various forests across mainland China.

PubMed

Sun, Suqi; Wang, Yunqi; Wang, Yujie; Zhang, Huilan; Yu, Lei; Liu, Yong; Zhu, Jinqi

2015-01-01

Increased anthropogenic nitrogen emissions and more severe environmental issues (e.g. air pollution, soil acidification, and plant nutrient imbalances) are striking forest ecosystems. Data on NH4+ and NO3- concentrations in throughfall and stemflow were collected to estimate variation characteristics of nitrogen concentrations through forest hydrological processes across China. A typical study was carried out in the three forest types in the Jinyun Mountain region of Chongqing, from May to October 2012. Nitrogen concentrations in throughfall and stemflow are higher than those in atmospheric precipitation. DIN concentrations in atmospheric precipitation, throughfall, and stemflow, across China and in the Jinyun Mountain region, were 2.18 and 1.51, 3.19 and 3.88, and 5.14 and 3.92 mg N L(-1), respectively. NH4+ concentration was higher than NO3- concentration, suggesting NH4+ is the dominant nitrogen component in China. Additionally, across China, a linear relationship existed between DIN and NH4+, and between DIN and NO3- in atmospheric precipitation. DIN concentrations in throughfall and stemflow changed with the observed changes in precipitation, and DIN concentrations in precipitation positively correlated with those in throughfall and in stemflow were also observed. Moreover, average DIN concentrations in throughfall and stemflow varied in different forest types, resulting from differences in forest canopy structures and tree species characteristics. In the Jinyun Mountain region, both throughfall and stemflow DIN concentrations were the highest in the mixed broadleaved/coniferous forest, followed by evergreen broadleaved forest, and the lowest in moso bamboo forest. Monthly variations of NH4+ and NO3- concentrations, in throughfall and stemflow, were observed in the Jinyun Mountain region.

Dissolved oxygen as a factor influencing nitrogen removal rates in a one-stage system with partial nitritation and Anammox process.

PubMed

Cema, G; Płaza, E; Trela, J; Surmacz-Górska, J

2011-01-01

A biofilm system with Kaldnes biofilm carrier was used in these studies to cultivate bacteria responsible for both partial nitritation and Anammox processes. Due to co-existence of oxygen and oxygen-free zones within the biofilm depth, both processes can occur in a single reactor. Oxygen that inhibits the Anammox process is consumed in the outer layer of the biofilm and in this way Anammox bacteria are protected from oxygen. The impact of oxygen concentration on nitrogen removal rates was investigated in the pilot plant (2.1 m3), supplied with reject water from the Himmerfjärden Waste Water Treatment Plant. The results of batch tests showed that the highest nitrogen removal rates were obtained for a dissolved oxygen (DO) concentration around 3 g O2 m(-3) At a DO concentration of 4 g O2 m(-3), an increase of nitrite and nitrate nitrogen concentrations in the batch reactor were observed. The average nitrogen removal rate in the pilot plant during a whole operating period oscillated around 1.3 g N m(-2)d(-1) (0.3 +/- 0.1 kg N m(-3)d(-1)) at the average dissolved oxygen concentration of 2.3 g O2 m(-3). The maximum value of a nitrogen removal rate amounted to 1.9 g N m(-2)d(-1) (0.47 kg N m(-3)d(-1)) and was observed for a DO concentration equal to 2.5 g O2 m(-3). It was observed that increase of biofilm thickness during the operational period, had no influence on nitrogen removal rates in the pilot plant.

Phosphorus and nitrogen concentrations and loads at Illinois River south of Siloam Springs, Arkansas, 1997-1999

USGS Publications Warehouse

Green, W. Reed; Haggard, Brian E.

2001-01-01

Water-quality sampling consisting of every other month (bimonthly) routine sampling and storm event sampling (six storms annually) is used to estimate annual phosphorus and nitrogen loads at Illinois River south of Siloam Springs, Arkansas. Hydrograph separation allowed assessment of base-flow and surfacerunoff nutrient relations and yield. Discharge and nutrient relations indicate that water quality at Illinois River south of Siloam Springs, Arkansas, is affected by both point and nonpoint sources of contamination. Base-flow phosphorus concentrations decreased with increasing base-flow discharge indicating the dilution of phosphorus in water from point sources. Nitrogen concentrations increased with increasing base-flow discharge, indicating a predominant ground-water source. Nitrogen concentrations at higher base-flow discharges often were greater than median concentrations reported for ground water (from wells and springs) in the Springfield Plateau aquifer. Total estimated phosphorus and nitrogen annual loads for calendar year 1997-1999 using the regression techniques presented in this paper (35 samples) were similar to estimated loads derived from integration techniques (1,033 samples). Flow-weighted nutrient concentrations and nutrient yields at the Illinois River site were about 10 to 100 times greater than national averages for undeveloped basins and at North Sylamore Creek and Cossatot River (considered to be undeveloped basins in Arkansas). Total phosphorus and soluble reactive phosphorus were greater than 10 times and total nitrogen and dissolved nitrite plus nitrate were greater than 10 to 100 times the national and regional averages for undeveloped basins. These results demonstrate the utility of a strategy whereby samples are collected every other month and during selected storm events annually, with use of regression models to estimate nutrient loads. Annual loads of phosphorus and nitrogen estimated using regression techniques could provide similar results to estimates using integration techniques, with much less investment.

Source Separation of Urine as an Alternative Solution to Nutrient Management in Biological Nutrient Removal Treatment Plants.

PubMed

Jimenez, Jose; Bott, Charles; Love, Nancy; Bratby, John

2015-12-01

Municipal wastewater contains a mixture of brown (feces and toilet paper), yellow (urine), and gray (kitchen, bathroom and wash) waters. Urine contributes approximately 70-80% of the nitrogen (N), 50-70% of the phosphorus (P) load and 60-70% of the pharmaceutical residues in normal domestic sewage. This study evaluated the impact of different levels of source separation of urine on an existing biological nutrient removal (BNR) process. A process model of an existing biological nutrient removal (BNR) plant was used. Increasing the amount of urine diverted from the water reclamation facilities, has little impact on effluent ammonia (NH₃-N) concentration, but effluent nitrate (NO₃-N) concentration decreases. If nitrification is necessary then no reduction in the sludge age can be realized. However, a point is reached where the remaining influent nitrogen load matches the nitrogen requirements for biomass growth, and no residual nitrogen needs to be nitrified. That allows a significant reduction in sludge age, implying reduced process volume requirements. In situations where nitrification is required, lower effluent nitrate (NO₃-N) concentrations were realized due to both the lower influent nitrogen content in the wastewater and a more favorable nitrogen-to-carbon ratio for denitrification. The external carbon requirement for denitrification decreases as the urine separation efficiency increases due to the lower influent nitrogen content in the wastewater and a more favorable nitrogen-to-carbon ratio for denitrification. The effluent phosphorus concentration decreases when the amount of urine sent to water reclamation facilities is decreased due to lower influent phosphorus concentrations. In the case of chemical phosphate removal, urine separation reduces the amount of chemicals required.

21 CFR 868.2385 - Nitrogen dioxide analyzer.

Code of Federal Regulations, 2014 CFR

2014-04-01

... 21 Food and Drugs 8 2014-04-01 2014-04-01 false Nitrogen dioxide analyzer. 868.2385 Section 868...) MEDICAL DEVICES ANESTHESIOLOGY DEVICES Monitoring Devices § 868.2385 Nitrogen dioxide analyzer. (a) Identification. The nitrogen dioxide analyzer is a device intended to measure the concentration of nitrogen...

21 CFR 868.2385 - Nitrogen dioxide analyzer.

Code of Federal Regulations, 2011 CFR

2011-04-01

... 21 Food and Drugs 8 2011-04-01 2011-04-01 false Nitrogen dioxide analyzer. 868.2385 Section 868...) MEDICAL DEVICES ANESTHESIOLOGY DEVICES Monitoring Devices § 868.2385 Nitrogen dioxide analyzer. (a) Identification. The nitrogen dioxide analyzer is a device intended to measure the concentration of nitrogen...

21 CFR 868.2385 - Nitrogen dioxide analyzer.

Code of Federal Regulations, 2012 CFR

2012-04-01

... 21 Food and Drugs 8 2012-04-01 2012-04-01 false Nitrogen dioxide analyzer. 868.2385 Section 868...) MEDICAL DEVICES ANESTHESIOLOGY DEVICES Monitoring Devices § 868.2385 Nitrogen dioxide analyzer. (a) Identification. The nitrogen dioxide analyzer is a device intended to measure the concentration of nitrogen...

21 CFR 868.2385 - Nitrogen dioxide analyzer.

Code of Federal Regulations, 2013 CFR

2013-04-01

... 21 Food and Drugs 8 2013-04-01 2013-04-01 false Nitrogen dioxide analyzer. 868.2385 Section 868...) MEDICAL DEVICES ANESTHESIOLOGY DEVICES Monitoring Devices § 868.2385 Nitrogen dioxide analyzer. (a) Identification. The nitrogen dioxide analyzer is a device intended to measure the concentration of nitrogen...

21 CFR 868.2385 - Nitrogen dioxide analyzer.

Code of Federal Regulations, 2010 CFR

2010-04-01

... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Nitrogen dioxide analyzer. 868.2385 Section 868...) MEDICAL DEVICES ANESTHESIOLOGY DEVICES Monitoring Devices § 868.2385 Nitrogen dioxide analyzer. (a) Identification. The nitrogen dioxide analyzer is a device intended to measure the concentration of nitrogen...

Longer-term Stream Nitrogen Dynamics after Wildfire and Salvage Harvesting: Implications for Management Concepts based on Trajectories of Post-disturbance Watershed Recovery.

NASA Astrophysics Data System (ADS)

Silins, U.; Emelko, M. B.; Bladon, K. D.; Stone, M.; Williams, C.; Martens, A. M.; Wagner, M. J.

2015-12-01

Biogeochemical processes reflecting interaction of vegetation and hydrology govern long-term export of nutrients such as nitrogen, phosphorus, and carbon over successional time scales. While management concepts of watershed "recovery" from disturbance back towards pre-disturbance conditions are often considered over much shorter timescales, few studies have directly explored watershed biogeochemical responses to disturbance long enough to directly document the longer-term trajectory of responses to severe land disturbance on nitrogen export. The objectives of this study were to document both the initial magnitude and patterns of longer-term recovery of stream nitrogen after the 2003 Lost Creek wildfire over nine years in front ranges of the Rocky Mountains in south-west Alberta, Canada. The study was conducted in seven instrumented catchments (4-14 km2), including burned, burned and salvage logged, and unburned (reference) conditions since 2004. Total nitrogen (TN) and nitrate (NO3-) concentrations and area-normalized yields were greater and more variable in burned and post-fire salvage logged catchments when compared with unburned catchments. Large initial increases in stream TN and NO3- production 1-3 years after both wildfire and post-fire salvage logging declined strongly to levels similar to, or below that of unburned watersheds 4-6 years after the fire, and continued to decline (although more slowly) 7-9 years after the wildfire. Post-fire salvage logging produced lower impacts on TN and NO3- in streams and these effects declined even more rapidly compared to the effects of wildfire alone. These changes closely corresponded to the early trajectory of establishment and rapid juvenile growth of post-fire regenerating forest vegetation in both catchment groups. While the concept of hydrologic recovery from disturbance is both a practical and meaningful concept for integrated landscape management for protection of forest water resources, the benchmark for "recovery" based on present conditions in undisturbed forests may vary widely depending on forest age and successional status.

Coupled hydrological and biogeochemical processes controlling variability of nitrogen species in streamflow during autumn in an upland forest

USGS Publications Warehouse

Sebestyen, Stephen D.; Shanley, James B.; Boyer, Elizabeth W.; Kendall, Carol; Doctor, Daniel H.

2014-01-01

Autumn is a season of dynamic change in forest streams of the northeastern United States due to effects of leaf fall on both hydrology and biogeochemistry. Few studies have explored how interactions of biogeochemical transformations, various nitrogen sources, and catchment flow paths affect stream nitrogen variation during autumn. To provide more information on this critical period, we studied (1) the timing, duration, and magnitude of changes to stream nitrate, dissolved organic nitrogen (DON), and ammonium concentrations; (2) changes in nitrate sources and cycling; and (3) source areas of the landscape that most influence stream nitrogen. We collected samples at higher temporal resolution for a longer duration than typical studies of stream nitrogen during autumn. This sampling scheme encompassed the patterns and extremes that occurred during base flow and stormflow events of autumn. Base flow nitrate concentrations decreased by an order of magnitude from 5.4 to 0.7 µmol L−1 during the week when most leaves fell from deciduous trees. Changes to rates of biogeochemical transformations during autumn base flow explained the low nitrate concentrations; in-stream transformations retained up to 72% of the nitrate that entered a stream reach. A decrease of in-stream nitrification coupled with heterotrophic nitrate cycling were primary factors in the seasonal nitrate decline. The period of low nitrate concentrations ended with a storm event in which stream nitrate concentrations increased by 25-fold. In the ensuing weeks, peak stormflow nitrate concentrations progressively decreased over closely spaced, yet similarly sized events. Most stormflow nitrate originated from nitrification in near-stream areas with occasional, large inputs of unprocessed atmospheric nitrate, which has rarely been reported for nonsnowmelt events. A maximum input of 33% unprocessed atmospheric nitrate to the stream occurred during one event. Large inputs of unprocessed atmospheric nitrate show direct and rapid effects on forest streams that may be widespread, although undocumented, throughout nitrogen-polluted temperate forests. In contrast to a week-long nitrate decline during peak autumn litterfall, base flow DON concentrations increased after leaf fall and remained high for 2 months. Dissolved organic nitrogen was hydrologically flushed to the stream from riparian soils during stormflow. In contrast to distinct seasonal changes in base flow nitrate and DON concentrations, ammonium concentrations were typically at or below the detection limit, similar to the rest of the year. Our findings reveal couplings among catchment flow paths, nutrient sources, and transformations that control seasonal extremes of stream nitrogen in forested landscapes.

The impact of silver nanoparticles on the co-composting of sewage sludge and agricultural waste: Evolutions of organic matter and nitrogen.

PubMed

Zhang, Lihua; Zeng, Guangming; Dong, Haoran; Chen, Yaoning; Zhang, Jiachao; Yan, Ming; Zhu, Yuan; Yuan, Yujie; Xie, Yankai; Huang, Zhenzhen

2017-04-01

This study evaluated the influence of silver nanoparticles (AgNPs) on evolutions of organic matter and nitrogen during co-composting of sewage sludge and agricultural waste. Two co-composting piles were conducted, one was treated without AgNPs (pile 1) and the other with AgNPs (pile 2). Results showed that the AgNPs affected the quality of final composts. Less organic matter (OM) losses were determined in pile 2 (57.96%) than pile 1 (61.66%). 27.22% and 30.1% of the initial total organic matter (TOC) was decomposed in pile 1 and pile 2, respectively. The final water soluble carbon (WSC) concentration in pile 2 was 23559.27mg/kg DW compost which was significantly lower than pile 1 (25642.75mg/kg DW compost). Changes of different forms of nitrogen in the two piles showed that AgNPs could reduce the losses of TN but increase the losses of mineral N. Copyright © 2017 Elsevier Ltd. All rights reserved.

Evaluation of medical stone amendment for the reduction of nitrogen loss and bioavailability of heavy metals during pig manure composting.

PubMed

Wang, Quan; Wang, Zhen; Awasthi, Mukesh Kumar; Jiang, Yahui; Li, Ronghua; Ren, Xiuna; Zhao, Junchao; Shen, Feng; Wang, Meijing; Zhang, Zengqiang

2016-11-01

The purpose of this research was to evaluate the effect of medical stone (MS) on nitrogen conservation and improving the compost quality during the pig manure (PM) composting. Five treatments were designed with different concentrations of MS0%, 2.5%, 5%, 7.5% and 10% (on dry weight of pig manure basis) mixed with initial feed stock and then composted for 60days. The results showed that MS amendment obviously (p<0.05) promoted the organic waste degradation and prolonged the thermophilic phase as well as enhanced the immobilization of heavy metals Cu and Zn. With increasing the amount of MS, the NH3 loss and N2O emission were significantly reduced by 27.9-48.8% and by 46.6-85.3%, respectively. Meanwhile, the MS amendment could reduce the NO2(-)-N formation and increase the NO3(-)-N content. Finally our results suggested that 10%MS addition could significantly reduce the nitrogen conservation as well as improve the quality of compost. Copyright © 2016 Elsevier Ltd. All rights reserved.

The Effects of Physicochemical Factors and Cell Density on Nitrite Transformation in a Lipid-Rich Chlorella.

PubMed

Liang, Fang; Du, Kui; Wen, Xiaobin; Luo, Liming; Geng, Yahong; Li, Yeguang

2015-12-28

To understand the effects of physicochemical factors on nitrite transformation by microalgae, a lipid-rich Chlorella with high nitrite tolerance was cultured with 8 mmol/l sodium nitrite as sole nitrogen source under different conditions. The results showed that nitrite transformation was mainly dependent on the metabolic activities of algal cells rather than oxidation of nitrite by dissolved oxygen. Light intensity, temperature, pH, NaHCO3 concentrations, and initial cell densities had significant effects on the rate of nitrite transformation. Single-factor experiments revealed that the optimum conditions for nitrite transformation were light intensity: 300 μmol/m(2); temperature: 30°C; pH: 7-8; NaHCO3 concentration: 2.0 g/l; and initial cell density: 0.15 g/l; and the highest nitrite transformation rate of 1.36 mmol/l/d was achieved. There was a positive correlation between nitrite transformation rate and the growth of Chlorella. The relationship between nitrite transformation rate (mg/l/d) and biomass productivity (g/l/d) could be described by the regression equation y = 61.3x (R(2) = 0.9665), meaning that 61.3 mg N element was assimilated by 1.0 g dry biomass on average, which indicated that the nitrite transformation is a process of consuming nitrite as nitrogen source by Chlorella. The results demonstrated that the Chlorella suspension was able to assimilate nitrite efficiently, which implied the feasibility of using flue gas for mass production of Chlorella without preliminary removal of NOX.

The Relative Concentrations of Nutrients and Toxins Dictate Feeding by a Vertebrate Browser, the Greater Glider Petauroides volans.

PubMed

Jensen, Lora M; Wallis, Ian R; Foley, William J

2015-01-01

Although ecologists believe that vertebrate herbivores must select a diet that allows them to meet their nutritional requirements, while avoiding intoxication by plant secondary metabolites, this is remarkably difficult to show. A long series of field and laboratory experiments means that we have a good understanding of the factors that affect feeding by leaf-eating marsupials. This knowledge and the natural intraspecific variation in Eucalyptus chemistry allowed us to test the hypothesis that the feeding decisions of greater gliders (Petauroides volans) depend on the concentrations of available nitrogen (incorporating total nitrogen, dry matter digestibility and tannins) and of formylated phloroglucinol compounds (FPCs), potent antifeedants unique to Eucalyptus. We offered captive greater gliders foliage from two species of Eucalyptus, E. viminalis and E. melliodora, which vary naturally in their concentrations of available nitrogen and FPCs. We then measured the amount of foliage eaten by each glider and compared this with our laboratory analyses of foliar total nitrogen, available nitrogen and FPCs for each tree offered. The concentration of FPCs was the main factor that determined how much gliders ate of E. viminalis and E. melliodora, but in gliders fed E. viminalis the concentration of available nitrogen was also a significant influence. In other words, greater gliders ate E. viminalis leaves with a particular combination of FPCs and available nitrogen that maximised the nutritional gain but minimised their ingestion of toxins. In contrast, the concentration of total nitrogen was not correlated with feeding. This study is among the first to empirically show that browsing herbivores select a diet that balances the potential gain (available nutrients) and the potential costs (plant secondary chemicals) of eating leaves. The major implication of the study is that it is essential to identify the limiting nutrients and relevant toxins in a system in order to understand feeding behaviour.

The Relative Concentrations of Nutrients and Toxins Dictate Feeding by a Vertebrate Browser, the Greater Glider Petauroides volans

PubMed Central

Jensen, Lora M.; Wallis, Ian R.; Foley, William J.

2015-01-01

Although ecologists believe that vertebrate herbivores must select a diet that allows them to meet their nutritional requirements, while avoiding intoxication by plant secondary metabolites, this is remarkably difficult to show. A long series of field and laboratory experiments means that we have a good understanding of the factors that affect feeding by leaf-eating marsupials. This knowledge and the natural intraspecific variation in Eucalyptus chemistry allowed us to test the hypothesis that the feeding decisions of greater gliders (Petauroides volans) depend on the concentrations of available nitrogen (incorporating total nitrogen, dry matter digestibility and tannins) and of formylated phloroglucinol compounds (FPCs), potent antifeedants unique to Eucalyptus. We offered captive greater gliders foliage from two species of Eucalyptus, E. viminalis and E. melliodora, which vary naturally in their concentrations of available nitrogen and FPCs. We then measured the amount of foliage eaten by each glider and compared this with our laboratory analyses of foliar total nitrogen, available nitrogen and FPCs for each tree offered. The concentration of FPCs was the main factor that determined how much gliders ate of E. viminalis and E. melliodora, but in gliders fed E. viminalis the concentration of available nitrogen was also a significant influence. In other words, greater gliders ate E. viminalis leaves with a particular combination of FPCs and available nitrogen that maximised the nutritional gain but minimised their ingestion of toxins. In contrast, the concentration of total nitrogen was not correlated with feeding. This study is among the first to empirically show that browsing herbivores select a diet that balances the potential gain (available nutrients) and the potential costs (plant secondary chemicals) of eating leaves. The major implication of the study is that it is essential to identify the limiting nutrients and relevant toxins in a system in order to understand feeding behaviour. PMID:25938422

Effects of elevated CO(2) concentration and nutrition on net photosynthesis, stomatal conductance and needle respiration of field-grown Norway spruce trees.

PubMed

Roberntz, Peter; Stockfors, Jan

1998-04-01

To study the effects of elevated CO(2) on gas exchange, nonstructural carbohydrate and nutrient concentrations in current-year foliage of 30-year-old Norway spruce (Picea abies (L.) Karst.) trees, branches were enclosed in ventilated, transparent plastic bags and flushed with ambient air (mean 370 &mgr;mol CO(2) mol(-1); control) or ambient air + 340 &mgr;mol CO(2) mol(-1) (elevated CO(2)) during two growing seasons. One branch bag was installed on each of 24 selected trees from control and fertilized plots. To reduce the effect of variation among trees, results from each treated branch were compared with those from a control branch on the same whorl of the same tree. Elevated CO(2) increased rates of light-saturated photosynthesis on average by 55% when measured at the treatment CO(2) concentration. The increase was larger in shoots with high needle nitrogen concentrations than in shoots with low needle nitrogen concentrations. However, shoots grown in elevated CO(2) showed a decrease in photosynthetic capacity compared with shoots grown in ambient CO(2). When measured at the internal CO(2) concentration of 200 &mgr;mol CO(2) mol(-1), photosynthetic rates of branches in the elevated CO(2) treatments were reduced by 8 to 32%. The elevated CO(2) treatment caused a 9 to 20% reduction in carboxylation efficiency and an 18% increase in respiration rates. In response to elevated CO(2), starch, fructose and glucose concentrations in the needles increased on average 33%, whereas concentrations of potassium, nitrogen, phosphorus, magnesium and boron decreased. Needle nitrogen concentrations explained 50-60% of the variation in photosynthesis and CO(2) acclimation was greater at low nitrogen concentrations than at high nitrogen concentrations. We conclude that the enhanced photosynthetic rates found in shoots exposed to elevated CO(2) increased carbohydrate concentrations, which may have a negative feedback on the photosynthetic apparatus and stimulate cyanide-resistant respiration. We also infer that the decrease in nutrient concentrations of needles exposed to elevated CO(2) was the result of retranslocation of nutrients to other parts of the branch or tree.

Distinguishing solid bitumens formed by thermochemical sulfate reduction and thermal chemical alteration

USGS Publications Warehouse

Kelemen, S.R.; Walters, C.C.; Kwiatek, P.J.; Afeworki, M.; Sansone, M.; Freund, H.; Pottorf, R.J.; Machel, H.G.; Zhang, T.; Ellis, G.S.; Tang, Y.; Peters, K.E.

2008-01-01

Insoluble solid bitumens are organic residues that can form by the thermal chemical alteration (TCA) or thermochemical sulfate reduction (TSR) of migrated petroleum. TCA may actually encompass several low temperature processes, such as biodegradation and asphaltene precipitation, followed by thermal alteration. TSR is an abiotic redox reaction where petroleum is oxidized by sulfate. It is difficult to distinguish solid bitumens associated with TCA of petroleum from those associated with TSR when both processes occur at relatively high temperature. The focus of the present work was to characterize solid bitumen samples associated with TCA or TSR using X-ray photoelectron spectroscopy (XPS). XPS is a surface analysis conducted on either isolated or in situ (>25 ??m diameter) solid bitumen that can provide the relative abundance and chemical speciation of carbon, organic and inorganic heteroatoms (NSO). In this study, naturally occurring solid bitumens from three locations, Nisku Fm. Brazeau River area (TSR-related), LaBarge Field Madison Fm. (TSR-related), and the Alaskan Brooks range (TCA-related), are compared to organic solids generated during laboratory simulation of the TSR and TCA processes. The abundance and chemical nature of organic nitrogen and sulfur in solid bitumens can be understood in terms of the nature of (1) petroleum precursor molecules, (2) the concentration of nitrogen by way of thermal stress and (3) the mode of sulfur incorporation. TCA solid bitumens originate from polar materials that are initially rich in sulfur and nitrogen. Aromaticity and nitrogen increase as thermal stress cleaves aliphatic moieties and condensation reactions take place. Organic sulfur in TCA organic solids remains fairly constant with increasing maturation (3.5 to ???17 sulfur per 100 carbons) into aromatic structures and to the low levels of nitrogen in their hydrocarbon precursors. Hence, XPS results provide organic chemical composition information that helps to distinguish whether solid bitumen, either in situ or removed and concentrated from the rock matrix, was formed via the TCA or TRS process. ?? 2008 Elsevier Ltd.

Optimization of the freezing process for hematopoietic progenitor cells: effect of precooling, initial dimethyl sulfoxide concentration, freezing program, and storage in vapor-phase or liquid nitrogen on in vitro white blood cell quality.

PubMed

Dijkstra-Tiekstra, Margriet J; Setroikromo, Airies C; Kraan, Marcha; Gkoumassi, Effimia; de Wildt-Eggen, Janny

2014-12-01

Adding dimethyl sulfoxide (DMSO) to hematopoietic progenitor cells (HPCs) causes an exothermic reaction, potentially affecting their viability. The freezing method might also influence this. The aim was to investigate the effect of 1) precooling of DMSO and plasma (D/P) and white blood cell (WBC)-enriched product, 2) DMSO concentration of D/P, 3) freezing program, and 4) storage method on WBC quality. WBC-enriched product without CD34+ cells was used instead of HPCs. This was divided into six or eight portions. D/P (20 or 50%; precooled or room temperature [RT]) was added to the WBC-enriched product (precooled or RT), resulting in 10% DMSO, while monitoring temperature. The product was frozen using controlled-rate freezing ("fast-rate" or "slow-rate") and placed in vapor-phase or liquid nitrogen. After thawing, WBC recovery and viability were determined. Temperature increased most for precooled D/P to precooled WBC-enriched product, without influence of 20 or 50% D/P, but remained for all variations below 30°C. WBC recovery for both freezing programs was more than 95%. Recovery of WBC viability was higher for slow-rate freezing compared to fast-rate freezing (74% vs. 61%; p < 0.05) and also for 50% compared to 20% D/P (two test variations). Effect of precooling D/P or WBC-enriched product and of storage in vapor-phase or liquid nitrogen was marginal. Based on these results, precooling is not necessary. Fifty percent D/P is preferred over 20% D/P. Slow-rate freezing is preferred over fast-rate freezing. For safety reasons storage in vapor-phase nitrogen is preferred over storage in liquid nitrogen. Additional testing using real HPCs might be necessary. © 2014 AABB.

Effect of Nitrite and Nitrate Concentrations on the Performance of AFB-MFC Enriched with High-Strength Synthetic Wastewater.

PubMed

Huang, Jian-Sheng; Yang, Ping; Li, Chong-Ming; Guo, Yong; Lai, Bo; Wang, Ye; Feng, Li; Zhang, Yun

2015-01-01

In order to study the effect of nitrite and nitrate on the performance of microbial fuel cell, a system combining an anaerobic fluidized bed (AFB) and a microbial fuel cell (MFC) was employed for high-strength nitrogen-containing synthetic wastewater treatment. Before this study, the AFB-MFC had been used to treat high-strength organic wastewater for about one year in a continuous flow mode. The results showed that when the concentrations of nitrite nitrogen and nitrate nitrogen were increased from 1700 mg/L to 4045 mg/L and 545 mg/L to 1427 mg/L, respectively, the nitrite nitrogen and nitrate nitrogen removal efficiencies were both above 99%; the COD removal efficiency went up from 60.00% to 88.95%; the voltage was about 375 ± 15 mV while the power density was at 70 ± 5 mW/m(2). However, when the concentrations of nitrite nitrogen and nitrate nitrogen were above 4045 mg/L and 1427 mg/L, respectively, the removal of nitrite nitrogen, nitrate nitrogen, COD, voltage, and power density were decreased to be 86%, 88%, 77%, 180 mV, and 17 mW/m(2) when nitrite nitrogen and nitrate nitrogen were increased to 4265 mg/L and 1661 mg/L. In addition, the composition of biogas generated in the anode chamber was analyzed by a gas chromatograph. Nitrogen gas, methane, and carbon dioxide were obtained. The results indicated that denitrification happened in anode chamber.

Nitrogen attenuation in the Connecticut River, northeastern USA; a comparison of mass balance and N2 production modeling approaches

USGS Publications Warehouse

Smith, T.E.; Laursen, A.E.; Deacon, J.R.

2008-01-01

Two methods were used to measure in-stream nitrogen loss in the Connecticut River during studies conducted in April and August 2005. A mass balance on nitrogen inputs and output for two study reaches (55 and 66 km), at spring high flow and at summer low flow, was computed on the basis of total nitrogen concentrations and measured river discharges in the Connecticut River and its tributaries. In a 10.3 km subreach of the northern 66 km reach, concentrations of dissolved N2 were also measured during summer low flow and compared to modeled N2 concentrations (based on temperature and atmospheric gas exchange rates) to determine the measured "excess" N2 that indicates denitrification. Mass balance results showed no in-stream nitrogen loss in either reach during April 2005, and no nitrogen loss in the southern 55 km study reach during August 2005. In the northern 66 km reach during August 2005, however, nitrogen output was 18% less than the total nitrogen inputs to the reach. N2 sampling results gave an estimated rate of N2 production that would remove 3.3% of the nitrogen load in the river over the 10.3 km northern sub-reach. The nitrogen losses measured in the northern reach in August 2005 may represent an approximate upper limit for nitrogen attenuation in the Connecticut River because denitrification processes are most active during warm summer temperatures and because the study was performed during the annual low-flow period when total nitrogen loads are small. ?? 2008 Springer Science+Business Media B.V.

Nitrogen isotopic fractionation during plasma synthesis of Titan's aerosols analogues

NASA Astrophysics Data System (ADS)

Kuga, M.; Carrasco, N.; Marty, B.; Marrocchi, Y.; Bernard, S.; Rigaudier, T.

2013-12-01

The Cassini-Huygens mission recently provided measurements of the abundance of nitrogen isotopes in Titan's atmosphere. The 14N/15N ratio in the two most abundant N-bearing molecules in Titan's atmosphere was found to be 183×5 for N2 [1] and 56×8 for HCN [2]. Those two molecules are greatly enriched in the heavier isotope 15N compared to our terrestrial atmosphere and Titan's HCN is about three times richer in 15N than its potential photochemical precursor N2. This implies an important fractionation process in the HCN production chain, which is tentatively attributed to an isotopic selectivity of the photodissociation of N2 in Titan's ionosphere [3-4]. The organic aerosols, forming the Titan's orange characteristic haze layers, also contain large amounts of nitrogen [5], and thus represent a third important nitrogen reservoir in Titan's atmosphere. These organic aerosols are presumably produced in the upper atmosphere by chemical reactions between N2 and CH4 induced by solar radiation and electron bombardment from Saturn's magnetosphere. As HCN is a possible precursor for aerosol polymerization [6-7], the 15N enrichment observed in HCN may be linked to the polymerization process. Unfortunately, no data exists on the isotopic nitrogen abundance in Titan's aerosols, and this question remains open. To address this issue, laboratory aerosols analogues have been produced in a N2-CH4 plasma and their nitrogen isotopic composition have been investigated. In this study, the experimental aerosols, called " tholins ", have been synthetized in the PAMPRE reactor (LATMOS, France). This setup is dedicated to simulate chemical processes occurring in Titan's atmosphere and consists in an RF plasma discharge initiated in a N2-CH4 gas mixture at room temperature [8-9]. For our purpose, tholins were produced at different initial CH4 percentages (1, 2, 5, 10%), representative of the variation of the CH4 concentration in Titan's atmosphere. 15N/14N ratio of the N2 gas used in the initial gas mixture was analyzed by dual-inlet and tholins nitrogen isotopes were measured by EA-IRMS. PAMPRE tholins are depleted in 15N by -15 to -25‰ relative to the initial N2. Comparison of this nitrogen isotopic fractionation with a N2-CO-H2O plasma experiment done in very similar experimental conditions and resulting in a very close 15N depletion, has led us to interpret this 15N depletion between N2 and organic aerosols as a kinetic isotopic fractionation occurring during N2 dissociation in the plasma. This nitrogen isotopic fractionation, although important and larger than what is observed in natural terrestrial samples, is weak compared to what is measured in Titan's atmosphere for N2 and HCN. This apparent inconsistency will be discussed. [1] Niemann et al. (2010) JGR, 115, 1151-1154. [2] Vinatier et al. (2007) Icarus, 191, 712-721. [3] Liang et al. (2007) Ap.J. Lett., 664, L115. [4] Croteau et al. (2011) Ap.J. Lett., 728, L32. [5] Israel et al. (2005) [6] Lebonnois et al. (2002) Icarus, 159, 505-517. [7] Lavvas et al. 2008) Planet. Space Sci., 56, 67-99. [8] Szopa et al. (2006) Planet. Space. Sci., 54, 394-404. [9] Sciamma-O'Brien et al. (2010) Icarus, 209, 704-714.

21 CFR 868.1690 - Nitrogen gas analyzer.

Code of Federal Regulations, 2012 CFR

2012-04-01

... 21 Food and Drugs 8 2012-04-01 2012-04-01 false Nitrogen gas analyzer. 868.1690 Section 868.1690...) MEDICAL DEVICES ANESTHESIOLOGY DEVICES Diagnostic Devices § 868.1690 Nitrogen gas analyzer. (a) Identification. A nitrogen gas analyzer is a device intended to measure the concentration of nitrogen in...

21 CFR 868.1690 - Nitrogen gas analyzer.

Code of Federal Regulations, 2013 CFR

2013-04-01

... 21 Food and Drugs 8 2013-04-01 2013-04-01 false Nitrogen gas analyzer. 868.1690 Section 868.1690...) MEDICAL DEVICES ANESTHESIOLOGY DEVICES Diagnostic Devices § 868.1690 Nitrogen gas analyzer. (a) Identification. A nitrogen gas analyzer is a device intended to measure the concentration of nitrogen in...

21 CFR 868.1690 - Nitrogen gas analyzer.

Code of Federal Regulations, 2014 CFR

2014-04-01

... 21 Food and Drugs 8 2014-04-01 2014-04-01 false Nitrogen gas analyzer. 868.1690 Section 868.1690...) MEDICAL DEVICES ANESTHESIOLOGY DEVICES Diagnostic Devices § 868.1690 Nitrogen gas analyzer. (a) Identification. A nitrogen gas analyzer is a device intended to measure the concentration of nitrogen in...

Post-fire Water Quality Response and Associated Physical Drivers

NASA Astrophysics Data System (ADS)

Rust, A.; Saxe, S.; Hogue, T. S.; McCray, J. E.; Rhoades, C.

2017-12-01

The frequency and severity of forest fires is increasing across the western US. Wildfires are known to impact water quality in receiving waters; many of which are important sources of water supply. Studies on individual forest fires have shown an increase in total suspended solids, nutrient and metal concentrations and loading in receiving streams. The current research looks at a large number of fires across a broad region (Western United States) to identify typical water quality changes after fire and the physical characteristics that drive those responses. This presentation will overview recent development of an extensive database on post-fire water quality. Across 172 fires, we found that water quality changed significantly in one out of three fires up to five years after the event compared to pre-burn conditions. For basins with higher frequency data, it was evident that water quality changes were significant in the first three years following fire. In both the initial years following fire and five years after fire, concentrations and loading rates of dissolved nutrients such as nitrite, nitrate and orthophosphate and particulate forms of nutrients, total organic nitrogen, total nitrogen, total phosphate, and total phosphorus increase thirty percent of the time. Concentrations of some major dissolved ions and metals decrease, with increased post-fire flows, while total particulate concentrations increased; the flux of both dissolved and particulate forms increase in thirty percent of the fires over five years. Water quality change is not uniform across the studied watersheds. A second goal of this study is to identify physical characteristics of a watershed that drive water quality response. Specifically, we investigate the physical, geochemical, and climatological characteristics of watersheds that control the type, direction, and magnitude of water quality change. Initial results reveal vegetation recovery is a key driver in post-fire water quality response. Ultimately, improved understanding of post-fire response and related drivers will advance potential mitigation and treatment strategies as well as aid in the parametrization of post-fire models of water quality.

Release of dissolved nitrogen from water during depressurization

NASA Technical Reports Server (NTRS)

Simoneau, R. J.

1978-01-01

Experiments were run to study depressurization of water containing various concentrations of dissolved nitrogen gas, the primary case being room temperature water saturated with nitrogen at 4 MPa. In a static depressurization experiment, water with very high nitrogen content was depressurized at rates from 0.09 to 0.50 MPa per second and photographed with high speed movies. The pictures showed that the bubble population at a given pressure increased strongly with decreasing depressurization rate. Flow experiments were performed in an axisymmetric converging-diverging nozzle and in a two-dimensional converging nozzle with glass sidewalls. Depressurization gradients were roughly 500 to 1200 MPa per second. Both nozzles exhibited choked flow behavior even at nitrogen concentration levels as low as 4 percent of saturated. The flow rates were independent of concentration level and could be computed as incompressible water flow based on the difference between stagnation and throat pressures; however, the throat pressures were significantly different between the two nozzles.

Polygonum sachalinense alters the balance between capacities of regeneration and carboxylation of ribulose-1,5-bisphosphate in response to growth CO2 increment but not the nitrogen allocation within the photosynthetic apparatus.

PubMed

Akita, Risako; Kamiyama, Chiho; Hikosaka, Kouki

2012-12-01

The limiting step of photosynthesis changes depending on CO(2) concentration and, in theory, photosynthetic nitrogen use efficiency at a respective CO(2) concentration is maximized if nitrogen is redistributed from non-limiting to limiting processes. It has been shown that some plants increase the capacity of ribulose-1,5-bisphoshate (RuBP) regeneration (evaluated as J(max) ) relative to the RuBP carboxylation capacity (evaluated as V(cmax) ) at elevated CO(2) , which is in accord with the theory. However, there is no study that tests whether this change is accompanied by redistribution of nitrogen in the photosynthetic apparatus. We raised a perennial plant, Polygonum sachalinense, at two nutrient availabilities under two CO(2) concentrations. The J(max) to V(cmax) ratio significantly changed with CO(2) increment but the nitrogen allocation among the photosynthetic apparatus did not respond to growth CO(2) . Enzymes involved in RuBP regeneration might be more activated at elevated CO(2) , leading to the higher J(max) to V(cmax) ratio. Our result suggests that nitrogen partitioning is not responsive to elevated CO(2) even in species that alters the balance between RuBP regeneration and carboxylation. Nitrogen partitioning seems to be conservative against changes in growth CO(2) concentration. Copyright © Physiologia Plantarum 2012.

Impact of available nitrogen and sugar concentration in musts on alcoholic fermentation and subsequent wine spoilage by Brettanomyces bruxellensis.

PubMed

Childs, Bradford C; Bohlscheid, Jeffri C; Edwards, Charles G

2015-04-01

The level of yeast assimilable nitrogen (YAN) supplementation required for Saccharomyces cerevisiae to complete fermentation of high sugar musts in addition to the impact of non-metabolized nitrogen on post-alcoholic spoilage by Brettanomyces bruxellensis was studied. A 2 × 3 factorial design was employed using a synthetic grape juice medium with YAN (150 or 250 mg N/L) and equal proportions of glucose/fructose (230, 250, or 270 g/L) as variables. S. cerevisiae ECA5 (low nitrogen requirement) or Uvaferm 228 (high nitrogen requirement) were inoculated at 10(5) cfu/mL while B. bruxellensis E1 or B2 were added once alcoholic fermentation ceased. Regardless of YAN concentration, musts that contained 230 or 250 g/L glucose/fructose at either nitrogen level attained dryness (mean = 0.32 g/L fructose) while those containing 270 g/L generally did not (mean = 2.5 g/L fructose). Higher concentrations of YAN present in musts yielded wines with higher amounts of α-amino acids and ammonium but very little (≤ 6 mg N/L) was needed by B. bruxellensis to attain populations ≥ 10(7) cfu/mL. While adding nitrogen to high sugar musts does not necessarily ensure completion of alcoholic fermentation, residual YAN did not affect B. bruxellensis growth as much as ethanol concentration. Copyright © 2014 Elsevier Ltd. All rights reserved.

Regulation of glutamine synthetase activity in the unicellular cyanobacterium Synechocystis sp. strain PCC 6803 by the nitrogen source: effect of ammonium.

PubMed Central

Mérida, A; Candau, P; Florencio, F J

1991-01-01

Glutamine synthetase activity from Synechocystis sp. strain PCC 6803 is regulated as a function of the nitrogen source available in the medium. Addition of 0.25 mM NH4Cl to nitrate-grown cells promotes a clear short-term inactivation of glutamine synthetase, whose enzyme activity decreases to 5 to 10% of the initial value in 25 min. The intracellular levels of glutamine, determined under various conditions, taken together with the results obtained with azaserine (an inhibitor of transamidases), rule out the possibility that glutamine per se is responsible for glutamine synthetase inactivation. Nitrogen starvation attenuates the ammonium-mediated glutamine synthetase inactivation, indicating that glutamine synthetase regulation is modulated through the internal balance between carbon-nitrogen compounds and carbon compounds. The parallelism observed between the glutamine synthetase activity and the internal concentration of alpha-ketoglutarate suggests that this metabolite could play a role as a positive effector of glutamine synthetase activity in Synechocystis sp. Despite the similarities of this physiological system to that described for enterobacteria, the lack of in vivo 32P labeling of glutamine synthetase during the inactivation process excludes the existence of an adenylylation-deadenylylation system in this cyanobacterium. Images PMID:1676397

Treatment of landfill leachate using ASBR combined with zeolite adsorption technology.

PubMed

Lim, Chi Kim; Seow, Ta Wee; Neoh, Chin Hong; Md Nor, Muhamad Hanif; Ibrahim, Zaharah; Ware, Ismail; Mat Sarip, Siti Hajar

2016-12-01

Sanitary landfilling is the most common way to dispose solid urban waste; however, improper landfill management may pose serious environmental threats through discharge of high strength polluted wastewater also known as leachate. The treatment of landfill leachate to fully reduce the negative impact on the environment, is nowadays a challenge. In this study, an aerobic sequencing batch reactor (ASBR) was proposed for the treatment of locally obtained real landfill leachate with initial ammoniacal nitrogen and chemical oxygen demand (COD) concentration of 1800 and 3200 mg/L, respectively. ASBR could remove 65 % of ammoniacal nitrogen and 30 % of COD during seven days of treatment time. Thereafter, an effective adsorbent, i.e., zeolite was used as a secondary treatment step for polishing the ammoniacal nitrogen and COD content that is present in leachate. The results obtained are promising where the adsorption of leachate by zeolite further enhanced the removal of ammoniacal nitrogen and COD up to 96 and 43 %, respectively. Furthermore, this combined biological-physical treatment system was able to remove heavy metals, i.e. aluminium, vanadium, chromium, magnesium, cuprum and plumbum significantly. These results demonstrate that combined ASBR and zeolite adsorption is a feasible technique for the treatment of landfill leachate, even considering this effluent's high resistance to treatment.

Ingestive Behavior and Nitrogen Balance of Confined Santa Ines Lambs Fed Diets Containing Soybean Hulls

PubMed Central

Bastos, Milena Patrícia Viana; de Carvalho, Gleidson Giordano Pinto; Pires, Aureliano José Vieira; Silva, Robério Rodrigues; Filho, Antônio Eustáquio; dos Santos, Edileusa de Jesus; Chagas, Daiane Maria Trindade; Barroso, Daniele Soares; Filho, George Abreu

2014-01-01

The objective of this study was to assess the effect of substituting corn with soybean hulls on the ingestive behavior and nitrogen balance of Santa Ines lambs. A total of 25 lambs with an initial body weight of 20±2 kg at approximately six months of age, sheltered individually in stalls (1.10 m×1.0 m), considering an entirely casual experimental delineation. Soybean hulls were substituted for corn at 0, 250, 500, 750, and 1,000 g/kg of dry matter (DM). The time spent feeding, ruminating, masticating, and resting was not affected by the substitution of corn with soybean hulls. In fact, the feeding efficiency in g DM/h and the rumination efficiency in g DM/bolus increased linearly with soybean hull substitution in the feed. Although the nitrogen balance was not altered by the use of soybean hulls as a substitute for corn in the diets of Santa Ines lambs, the N ingested and N digested expressed in g/d, N retained as a percentage of that ingested, and N retained as a percentage of that digested displayed quadratic behavior. In conclusion, corn can be substituted with soybean hulls up to 1,000 g/kg of dry matter in the concentrate, without changing the ingestive behavior and nitrogen balance. PMID:25049922

N cycling in SPRUCE (Spruce Peatlands Response Under ...

EPA Pesticide Factsheets

Peatlands located in boreal regions make up a third of global wetland area and are expected to have the highest temperature increases in response to climate change. As climate warms, we expect peat decomposition may accelerate, altering the cycling of nitrogen. Alterations in the nitrogen cycle can have consequences on NO3, NH4 availability or pollution, and potentially increase nitrous oxide (N2O) emissions, a persistent greenhouse gas (GHG). These consequences can cascade to altering whole ecosystem functions and effecting human health.We are investigating nitrogen cycling response to elevated temperature and CO2 in a boreal peatland. Spruce and Peatland Responses Under Climate and Environmental Change (SPRUCE) project initiated soil warming in 2014 in ten peatland mesocosms (five temperature treatments from ambient (+0°C) to +9°C) and elevated CO2 in half of the mesocosms in 2016. Peat cores at three depths (acrotelm, catotelm, deep peat) were analyzed in the laboratory for denitrification, nitrification, and ammonification. We expect denitrification, nitrification, and ammonification rates to increase, and denitrification efficiency to decrease with rising temperatures- potentially contaminating water resources with NO3, NH4 and increase N2O concentrations in our atmosphere. This research will enhance the scientific understanding of how nitrogen cycling, an important functional eco-service, responds under environmental conditions including elevated CO2

Short chain nitrocompounds as a treatment of layer hen manure and litter; effects on in vitro survivability of Salmonella, generic E. coli and nitrogen metabolism.

PubMed

Ruiz-Barrera, Oscar; Anderson, Robin C; Hume, Michael E; Corrales-Millan, Jonatan; Castillo-Castillo, Yamicela; Corral-Luna, Agustin; Guevara-Valdez, Jose Luis; Salinas-Chavira, Jaime; Rodriguez-Muela, Carlos; Arzola-Alvarez, Claudio

2017-01-02

The current study was conducted to assess the bactericidal effectiveness of several nitrocompounds against pathogens in layer hen manure and litter. Evidence from an initial study indicated that treatment of layer hen manure with 12 mM nitroethane decreased populations of generic E. coli and total coliforms by 0.7 and 2.2 log 10 colony forming units (CFU) g -1 , respectively, after 24 h aerobic incubation at ambient temperature when compared to untreated populations. Salmonella concentrations were unaffected by nitroethane in this study. In a follow-up experiment, treatment of 6-month-old layer hen litter (mixed with 0.4 mL water g -1 ) with 44 mM 2-nitroethanol, 2-nitropropanol or ethyl nitroacetate decreased an inoculated Salmonella typhimurium strain from its initial concentration (3 log 10 CFU g -1 ) by 0.7 to 1.7 log 10 CFU g -1 after 6 h incubation at 37°C in covered containers. After 24 h incubation, populations of the inoculated S. Typhmiurium in litter treated with 44 mM 2-nitroethanol, 2-nitropropanol, ethyl nitroacetate or nitroethane were decreased more than 3.2 log 10 CFU g -1 compared to populations in untreated control litter. Treatment of litter with 44 mM 2-nitroethanol, 2-nitropropanol, ethyl nitroacetate decreased rates of ammonia accumulation more than 70% compared to untreated controls (0.167 µmol mL -1 h -1 ) and loses of uric acid (< 1 µmol mL -1 ) were observed only in litter treated with 44 mM 2-nitropropanol, indicating that some of these nitrocompounds may help prevent loss of nitrogen in treated litter. Results warrant further research to determine if these nitrocompounds can be developed into an environmentally sustainable and safe strategy to eliminate pathogens from poultry litter, while preserving its nitrogen content as a nutritionally valuable crude protein source for ruminants.

Do lichens have "memory" of their native nitrogen environment?

PubMed

Munzi, Silvana; Loppi, Stefano; Cruz, Cristina; Branquinho, Cristina

2011-02-01

This study aimed to deepen the knowledge about intraspecific mechanisms regulating nitrogen tolerance in lichens to wet nitrogen deposition. Thalli of the nitrophilous lichen Xanthoria parietina were collected from environments with different nitrogen availabilities and immersed in 80 mL of ammonium sulphate (NH₄)₂SO₄ solutions with distinct concentrations (0, 0.025, 0.05 and 0.25 M) for 5 h per day during 3 days in a week. After each soaking event, lichens were air dried. After each treatment, maximal PSII efficiency, localization of ammonium ions, concentrations of K+ and Mg²+ and thalli buffer capacity were determined. Our results show that lichens are marked by their native nitrogen environment, since there were important differences between the physiological responses of X. parietina thalli previously grown in an area with high nitrogen deposition (nitrogen emissions of ca. 13,000 t/year) and those previously grown in an unpolluted area (nitrogen emissions of ca. 500 t/year). Greater N availability seems to enable X. parietina to cope better with the effects of nitrogen pollution.

Effects of climate, CO2 concentration, nitrogen deposition, and stand age changes on the carbon budget of China's forests

NASA Astrophysics Data System (ADS)

Zhang, C.; Ju, W.; Zhang, F.; Mao, D.; Wang, X.

2017-12-01

Forests play an irreplaceable role in the Earth's terrestrial carbon budget which retard the atmospheric CO2 buildup. Understanding the factors controlling forest carbon budget is critical for reducing uncertainties in projections of future climate. The relative importance of climate, atmospheric CO2 concentration, nitrogen deposition, and stand age changes on carbon budget, however, remains unclear for China's forests. In this study, we quantify individual contribution of these drivers to the trends of forest carbon budget in China from 1901 to 2012 by integrating national datasets, the updated Integrated Terrestrial Ecosystem Carbon Cycle (InTEC) model and factorial simulations. Results showed that the average carbon sink in China's forests from 1982 to 2012 was 186.9 Tg C yr-1 with 68% (127.6 Tg C yr-1) of the sink in living biomass because of the integrated effects of climate, atmospheric CO2 concentration, nitrogen deposition, and stand age factors. Compared with the simulation of all factors combined, the estimated carbon sink during 1901-2012 would be reduced by 41.8 Tg C yr-1 if climate change, atmospheric CO2 concentration and nitrogen deposition factors were omitted, and reduced by 25.0 Tg C yr-1 if stand age factor was omitted. In most decades, these factors increased forest carbon sinks with the largest of 101.3, 62.9, and 44.0 Tg C yr-1 from 2000 to 2012 contributed by stand age, CO2 concentration and nitrogen deposition, respectively. During 1901-2012, climate change, CO2 concentration, nitrogen deposition and stand age contributed -13.3, 21.4, 15.4 and 25.0 Tg C yr-1 to the averaged carbon sink of China's forests, respectively. Our study also showed diverse regional patterns of forest carbon budget related to the importance of driving factors. Stand age effect was the largest in most regions, but the effects of CO2 concentration and nitrogen deposition were dominant in southern China.

Short-term responses of soil water chemistry to nitrogen reduction in a subtropical forest ecosystem in southwest China

NASA Astrophysics Data System (ADS)

Duan, L.; Xie, D.; Zhang, T.; Huang, Y.

2017-12-01

Reactive nitrogen emission and deposition has been greatly reduced in recent years in China. To study the responses of soil water chemistry to decreasing nitrogen deposition, a field manipulating experiment was carried out in Tieshanping, a nitogen-saturated forest near Chongqing city in southwest China. After ten-year application of NH4NO3 or NaNO3 to simulate doubling nitrogen deposition with different nitrogen forms during 2005-2014, the nitrogen fertilizers were stopped applying at the end of 2014 to simulate decrease in nitrogen deposition. The continuous observing results on the changes of soil water chemistry in the next two years (2015 and 2016) showed very quick decrease in NO3- (the major form of inorganic nitrogen in soil water, because almost all NH4+ added being nitrified) concentration at the nitrogen fertilizing plots, to similar level at the reference plots without N fertilizer application. The NO3- concentrations of soil water at the NH4NO3 plots were even lower than those at the NaNO3 plots. The previous experiment on the effects of nitrogen addition had showed that NH4+ deposition, instead of NO3- deposition, increased N retention in the forest ecosystem, and led to lower NO3- concentration in soil water. The nitrogen sink seemed remained in the two years after the cease of N addition. Although the total NO3- leaching decreased after nitrogen reduction, the pH of soil water had not showed significantly increasing trend. Therefore, the recovery of Tieshanping forest ecosystem from acidification was slow, which requiring further emission abatement of reactive nitrogen in the future.

40 CFR 1065.750 - Analytical gases.

Code of Federal Regulations, 2010 CFR

2010-07-01

... O2 concentration in the exhaust sample is zero, we recommend using a balance gas of purified nitrogen... concentration in the exhaust sample is zero, we recommend using a balance gas of purified nitrogen. (3) Use the....41) mol/mol, balance He, and a stated total hydrocarbon concentration of 0.05 µmol/mol or less. (ii...

40 CFR 1065.750 - Analytical gases.

Code of Federal Regulations, 2012 CFR

2012-07-01

... O2 concentration in the exhaust sample is zero, we recommend using a balance gas of purified nitrogen... concentration in the exhaust sample is zero, we recommend using a balance gas of purified nitrogen. (3) Use the....41) mol/mol, balance He, and a stated total hydrocarbon concentration of 0.05 µmol/mol or less. (ii...

40 CFR 1065.750 - Analytical gases.

Code of Federal Regulations, 2013 CFR

2013-07-01

... O2 concentration in the exhaust sample is zero, we recommend using a balance gas of purified nitrogen... concentration in the exhaust sample is zero, we recommend using a balance gas of purified nitrogen. (3) Use the....41) mol/mol, balance He, and a stated total hydrocarbon concentration of 0.05 µmol/mol or less. (ii...

40 CFR 1065.750 - Analytical gases.

Code of Federal Regulations, 2011 CFR

2011-07-01

... O2 concentration in the exhaust sample is zero, we recommend using a balance gas of purified nitrogen... concentration in the exhaust sample is zero, we recommend using a balance gas of purified nitrogen. (3) Use the....41) mol/mol, balance He, and a stated total hydrocarbon concentration of 0.05 µmol/mol or less. (ii...

RELATIONSHIPS BETWEEN SUMMER CONCENTRATIONS OF TOTAL NITROGEN AND CHLOROPHYLL A IN TEN COASTAL SYSTEMS IN THE EASTERN UNITED STATES

EPA Science Inventory

We have examined relationships between summer (JuneAugust) average concentrations of total nitrogen (TN) and chlorophyll a (chl a) concentrations in the near-shore Mid-Atlantic Bight and nine bays and estuaries in the eastern United States: Boston Harbor/Massachusetts Bay, Long I...

[Optical emission analyses of N2/TMG ECR plasma for deposition of GaN film].

PubMed

Fu, Si-Lie; Wang, Chun-An; Chen, Jun-Fang

2013-04-01

The optical emission spectroscopy of hybrid N2/trimethylgallium (TMG) plasma in an ECR-PECVD system was investigated. The results indicate that the TMG gas is strongly dissociated into Ga*, CH and H even under self-heating condition. Ga species and nitrogen molecule in metastable state are dominant in hybrid ECR plasma. The concentration of metastable nitrogen molecule increases with the microwave power. On the other hand, the concentration of excited nitrogen molecules and of nitrogen ion decreases when the microwave power is higher than 400 W.

Corrosion of V?Ti?Cr alloys in liquid lithium: influence of alloy composition and concentration of nitrogen in lithium

NASA Astrophysics Data System (ADS)

Eliseeva, O. I.; Fedirko, V. N.; Chernov, V. M.; Zavialsky, L. P.

2000-12-01

The effect of V-(0-70)Ti-(0-30)Cr (at.%) compositions on their compatibility with nitrogen-containing lithium (0.0015-0.67 at.% N) at 7000°C under steady-state test conditions and long-term contact with lithium (up to 2000 h) has been studied. The conditions for formation and stable coexistence of nitride layers on the surface of various compositions under variable nitrogen concentration in lithium have been defined. The V-(8-10)Ti-(4-5)Cr compositions showed the best characteristics from the standpoint of corrosion resistance, nitride layer stability under conditions of variable nitrogen concentration in lithium, and the possibility of 'in situ' protective nitride layer formation.

Pre-breeding blood urea nitrogen concentration and reproductive performance of Bonsmara heifers within different management systems.

PubMed

Tshuma, Takula; Holm, Dietmar Erik; Fosgate, Geoffrey Theodore; Lourens, Dirk Cornelius

2014-08-01

This study investigated the association between pre-breeding blood urea nitrogen (BUN) concentration and reproductive performance of beef heifers within different management systems in South Africa. Bonsmara heifers (n = 369) from five herds with different estimated levels of nitrogen intake during the month prior to the commencement of the breeding season were sampled in November and December 2010 to determine BUN concentrations. Body mass, age, body condition score (BCS) and reproductive tract score (RTS) were recorded at study enrolment. Trans-rectal ultrasound and/or palpation was performed 4-8 weeks after a 3-month breeding season to estimate the stage of pregnancy. Days to pregnancy (DTP) was defined as the number of days from the start of the breeding season until the estimated conception date. Logistic regression and Cox proportional hazards survival analysis were performed to estimate the association of pre-breeding BUN concentration with subsequent pregnancy and DTP, respectively. After stratifying for herd and adjusting for age, heifers with relatively higher pre-breeding BUN concentration took longer to become pregnant when compared to those with relatively lower BUN concentration (P = 0.011). In the herd with the highest estimated nitrogen intake (n = 143), heifers with relatively higher BUN were less likely to become pregnant (P = 0.013) and if they did, it was only later during the breeding season (P = 0.017), after adjusting for body mass. These associations were not present in the herd (n = 106) with the lowest estimated nitrogen intake (P > 0.500). It is concluded that Bonsmara heifers with relatively higher pre-breeding BUN concentration, might be at a disadvantage because of this negative impact on reproductive performance, particularly when the production system includes high levels of nitrogen intake.

Bioelectrode-based approach for enhancing nitrate and nitrite removal and electricity generation from eutrophic lakes.

PubMed

Zhang, Yifeng; Angelidaki, Irini

2012-12-01

Nitrate and nitrite contamination of surface waters (e.g. lakes) has become a severe environmental and health problem, especially in developing countries. The recent demonstration of nitrate reduction at the cathode of microbial fuel cell (MFC) provides an opportunity to develop a new technology for nitrogen removal from surface waters. In this study, a sediment-type MFC based on two pieces of bioelectrodes was employed as a novel in situ applicable approach for nitrogen removal, as well as electricity production from eutrophic lakes. Maximum power density of 42 and 36 mW/m(2) was produced respectively from nitrate- and nitrite-rich synthetic lake waters at initial concentration of 10 mg-N/L. Along with the electricity production a total nitrogen removal of 62% and 77% was accomplished, for nitrate and nitrite, respectively. The nitrogen removal was almost 4 times higher under close-circuit condition with biocathode, compared to either the open-circuit operation or with abiotic cathode. The mass balance on nitrogen indicates that most of the removed nitrate and nitrite (84.7 ± 0.1% and 81.8 ± 0.1%, respectively) was reduced to nitrogen gas. The nitrogen removal and power generation was limited by the dissolved oxygen (DO) level in the water and acetate level injected to the sediment. Excessive oxygen resulted in dramatically decrease of nitrogen removal efficiency and only 7.8% removal was obtained at DO level of 7.8 mg/l. The power generation and nitrogen removal increased with acetate level and was nearly saturated at 0.84 mg/g-sediment. This bioelectrode-based in situ approach is attractive not only due to the electricity production, but also due to no need of extra reactor construction, which may broaden the application possibilities of sediment MFC technology. Copyright © 2012 Elsevier Ltd. All rights reserved.

Effect of feeding higher concentrations of limiting amino acids on performance, slaughter variables and nitrogen retention in broiler chicken fed graded levels of toasted guar (Cyamopsis tetragonoloba) meal.

PubMed

Rao, S V Rama; Raju, M V L N; Prakash, B; Rajkumar, U; Srilatha, T; Reddy, E P K

2018-06-01

An experiment was conducted to study the effect of supplementing higher concentrations (100 vs. 110%) of critical amino acids (CAA) on performance (body weight gain - BWG, feed efficiency - FE), slaughter variables and nitrogen retention in broiler chicken (1-6 weeks of age) fed graded levels of toasted guar meal (TGM) as a protein source in diets. The TGM was included at five graded concentrations (0, 50, 100, 150and200 g/kg) in iso-caloric and iso-protein diets with either the recommended concentration (100%) of CAA (lysine, total sulphur amino acids, threonine, tryptophan and valine) or at 10% higher (110%) concentration. A metabolism trial of three-day duration was conducted during sixth week of age to study nitrogen retention. The TGM levels and CAA concentration at 21 or 42 d of age did not influence BWG, FI and FE. BWG was not affected with inclusion of TGM up to 100 g/kg in starter and overall production (1 - 42 d of age) phases. The FE improved with TGM supplementation during starter phase, while at the end of experiment (42 d), FE was depressed by inclusion of TGM in dose dependant manner. All performance variables improved with increase in concentration of CAA from 100 to 110%. Breast meat weight improved and abdominal fat weight reduced with higher levels of CAA in diet. Retention of nitrogen reduced with increase in level of TGM in broiler diet. Increasing concentrations of CAA in diet improved nitrogen retention. It was concluded that TGM could be incorporated up to 100 g/kg with 100% CAA and up to 150 g/kg with 110% CAA without affecting performance. Increasing CAA concentration (110%) in diets significantly improved BWG and FE (21 and 42 d), breast meat weight and nitrogen retention in broiler chicken.

Interrelated responses of tomato plants and the leaf miner Tuta absoluta to nitrogen supply.

PubMed

Larbat, R; Adamowicz, S; Robin, C; Han, P; Desneux, N; Le Bot, J

2016-05-01

Plant-insect interactions are strongly modified by environmental factors. This study evaluates the influence of nitrogen fertilisation on the tomato (Solanum lycopersicum L.) cv. Santa clara and the leafminer (Tuta absoluta (Meyrick), Lepidoptera: Gelechiidae). Greenhouse-grown tomato plants were fed hydroponically on a complete nutrient solution containing either a high nitrogen concentration (HN) sustaining maximum growth or a low nitrogen concentration (LN) limiting plant growth. Insect-free plants were compared with plants attacked by T. absoluta. Seven and 14 days after artificial oviposition leading to efficacious hatching and larvae development, we measured total carbon, nitrogen and soluble protein as well as defence compounds (phenolics, glycoalkaloids, polyphenol oxidase activity) in the HN versus LN plants. Only in the HN treatment did T. absoluta infestation slightly impair leaf growth and induce polyphenol oxidase (PPO) activity in the foliage. Neither the concentration of phenolic compounds and proteins nor the distribution of nitrogen within the plant was affected by T. absoluta infestation. In contrast, LN nutrition impaired T. absoluta-induced PPO activity. It decreased protein and total nitrogen concentration of plant organs and enhanced the accumulation of constitutive phenolics and tomatine. Moreover, LN nutrition impaired T. absoluta development by notably decreasing pupal weight and lengthening the development period from egg to adult. Adjusting the level of nitrogen nutrition may thus be a means of altering the life cycle of T. absoluta. This study provides a comprehensive dataset concerning interrelated responses of tomato plants and T. absoluta to nitrogen nutrition. © 2015 German Botanical Society and The Royal Botanical Society of the Netherlands.

Nitrogen removal capacity and bacterial community dynamics of a Canon biofilter system at different organic matter concentrations.

PubMed

García-Ruiz, María J; Maza-Márquez, Paula; González-López, Jesús; Osorio, Francisco

2018-02-01

Three Canon bench-scale bioreactors with a volume of 2 L operating in parallel were configured as submerged biofilters. In the present study we investigated the effects of a high ammonium concentration (320 mgNH 4 + · L -1 ) and different concentrations of organic matter (0, 100 and 400 mgCOD·L -1 ) on the nitrogen removal capacity and the bacterial community structure. After 60 days, the Canon biofilters operated properly under concentrations of 0 and 100 mgCOD·L -1 of organic matter, with nitrogen removal efficiencies up to 85%. However, a higher concentration of organic matter (400 mgCOD·L -1 ) produced a partial inhibition of nitrogen removal (68.1% efficiency). The addition of higher concentrations of organic matter a modified the bacterial community structure in the Canon biofilter, increasing the proliferation of heterotrophic bacteria related to the genera of Thauera, Longilinea, Ornatilinea, Thermomarinilinea, unclassified Chlorobiales and Denitratisoma. However, heterotrophic bacteria co-exist with Nitrosomonas and Candidatus Scalindua. Thus, our study confirms the co-existence of different microbial activities (AOB, Anammox and denitrification) and the adaptation of a fixed-biofilm system to different concentrations of organic matter. Copyright © 2017 Elsevier Ltd. All rights reserved.

Geohydrology of, and nitrogen and chloride in, the glacial aquifer, Milford-Matamoras area, Pike County, Pennsylvania

USGS Publications Warehouse

Senior, L.A.

1994-01-01

The glacial aquifer that underlies the Routes 209 and 6 corridor between Milford and Matamoras, Pa., is one of the most productive in Pike County. The aquifer is comprised of unconsolidated glacial outwash and kame-terrace deposits that lie within a glacially carved valley now occupied by the Delaware River. Most businesses and residences along this narrow, 7-mile-long corridor rely on individual wells for water supply and septic systems for waste-water disposal. A study of nutrients and chloride in ground water in the glacial aquifer was conducted to determine the effect of these constituents contributed from septic systems and road runoff on ground-water quality. Sources of nutrients and chloride in the recharge zone upgradient of the aquifer include road and parking-lot runoff, septic systems, and precipitation. Nitrate and chloride from these sources can infiltrate and move in the direction of ground-water flow in the saturated zone of the aquifer. A water-table map based on 29 water levels measured in August 1991 indicates that the direction of ground-water flow is from the edges of the valley toward t he Delaware River but is nearly parallel to the Delaware River in the central area of the valley. The average concentrations of nitrogen and chloride in recharge and total annual loads of nitrogen and chloride to ground water were estimated for six areas with different population densities. These estimates assumed a recharge rate to the glacial aquifer of 20 inches per year and a 15 percent loss of chloride and nitrogen in the atmospheric precipitation to surface runoff. The estimated average concentration of nitrogen in recharge ranged from 2.5 to 10 mg/L (milligrams per liter), which corresponds to a total annual load of nitrogen as ammonium released from septic tanks and present in precipitation was oxidized to nitrate as the dominant nitrogen species in ground water. Contributions of nitrogen from septic tanks were greater than contributions from runoff. Observed concentrations of nitrate, which was the most abundant nitrogen species in ground water in t he glacial aquifer, ranged from less than 0.05 to 5.1 mg/L as nitrogen, with a median of 1.1 mg/L as nitrogen. Concentrations of nitrogen measured in ground water were lower than estimated concentrations for recharge suggesting that dissolved nitrogen species may not be conservative in ground water. Nitrate is unstable in anoxic ground water and can be removed by denitrification. Ammonium can be sorbed onto the aquifer materials. Evidence for reducing conditions included a positive correlation between low concentrations of dissolved oxygen and low concentrations of nitrate. The estimated concentration of chloride in recharge ranged from 6.7 to 21 mg/L, and total annual load of chloride to ground water ranged from 19.4 to 50.6 x 10(3) lb/mi2. Chloride is considered to be a chemically conservative ion in ground water. Contributions of chloride to ground water from road salting were greater than contributions from septic tanks. Observed concentrations of chloride in 18 ground-water samples from the glacial aquifer ranged from 2.1 to 32 mg/L, with a median of 17.5 mg/L. Local contamination is indicated by the elevated concentrations of chloride (up to 680 mg/L) detected in four wells located downgradient of an abandoned industry that may have released salts in processing waste. Chloride concentrations in ground water appeared to be greater near major roads and in areas of relatively greater septic-system density than in areas upgradient of roads, farther downgradient from roads, or with less densely spaced septic systems.

Analysis of hyperspectral field radiometric data for monitoring nitrogen concentration in rice crops

NASA Astrophysics Data System (ADS)

Stroppiana, D.; Boschetti, M.; Confalonieri, R.; Bocchi, S.; Brivio, P. A.

2005-10-01

Monitoring crop conditions and assessing nutrition requirements is fundamental for implementing sustainable agriculture. Rational nitrogen fertilization is of particular importance in rice crops in order to guarantee high production levels while minimising the impact on the environment. In fact, the typical flooded condition of rice fields can be a significant source of greenhouse gasses. Information on plant nitrogen concentration can be used, coupled with information about the phenological stage, to plan strategies for a rational and spatially differentiated fertilization schedule. A field experiment was carried out in a rice field Northern Italy, in order to evaluate the potential of field radiometric measurements for the prediction of rice nitrogen concentration. The results indicate that rice reflectance is influenced by nitrogen supply at certain wavelengths although N concentration cannot be accurately predicted based on the reflectance measured at a given wavelength. Regression analysis highlighted that the visible region of the spectrum is most sensitive to plant nitrogen concentration when reflectance measures are combined into a spectral index. An automated procedure allowed the analysis of all the possible combinations into a Normalized Difference Index (NDI) of the narrow spectral bands derived by spectral resampling of field measurements. The derived index appeared to be least influenced by plant biomass and Leaf Area Index (LAI) providing a useful approach to detect rice nutritional status. The validation of the regressive model showed that the model is able to predict rice N concentration (R2=0.55 [p<0.01] RRMSE=29.4; modelling efficiency close to the optimum value).

Influence on wine biogenic amine composition of modifications to soil N availability and grapevine N by cover crops.

PubMed

Pérez-Álvarez, Eva P; Garde-Cerdán, Teresa; Cabrita, Maria João; García-Escudero, Enrique; Peregrina, Fernando

2017-11-01

Vineyard soil management can modify the nitrogen soil availability and, therefore, grape amino acid content. These compounds are precursors of biogenic amines, which have negative effects on wine quality and human health. The objective was to study whether the effect of conventional tillage and two cover crops (barley and clover) on grapevine nitrogen status could be related to wine biogenic amines. Over 4 years, soil NO 3 - -N, nitrogen content in leaf and wine biogenic amine concentration were determined. Barley reduced soil NO 3 - -N availability and clover increased it. In 2011, at bloom, nitrogen content decreased with barley treatment in both blade and petiole. In 2012, nitrogen content in both leaf tissues at bloom was greater with clover than with tillage and barley treatments. Also, total biogenic amines decreased in barley with respect to tillage and clover treatments. There were correlations between some individual and total biogenic amine concentrations with respect to nitrogen content in leaf tissues. Wine biogenic amine concentration can be affected by the grapevine nitrogen status, provoked by changes in the soil NO 3 - -N availability with both cover crop treatments. © 2017 Society of Chemical Industry. © 2017 Society of Chemical Industry.

Global Coupled Carbon and Nitrogen Models: Successes, Failures and What next?

NASA Astrophysics Data System (ADS)

Holland, E. A.

2011-12-01

Over the last few years, there has been a great deal of progress in modeling coupled terrestrial global carbon and nitrogen cycles and their roles in Earth System models. The collection of recent models provides some surprising results and insights. A critical question for Earth system models is: How do the coupled C/N model results impact atmospheric carbon dioxide concentrations compared to carbon only models? Some coupled models predict increased atmospheric carbon dioxide concentrations, the result expected from nitrogen-limited photosynthesis uptake of carbon dioxide, while others predict little change or decreased carbon dioxide uptake with a coupled carbon and nitrogen cycle. With this range of impacts for climate critical atmospheric carbon dioxide concentrations, there is clearly a need for additional comparison of measurements and models. Randerson et al.'s CLAMP study provided important constraints and comparison for primarily for aboveground carbon uptake. However, nitrogen supply is largely determined decomposition and soil processes. I will present comparisons of NCAR's CESM results with soil and litter carbon and nitrogen fluxes and standing stocks. These belowground data sets of both carbon and nitrogen provide important benchmarks for coupled C/N models.

Optical and Electron Spin Resonance Studies of Destruction of Porous Structures Formed by Nitrogen-Rare Gas Nanoclusters in Bulk Superfluid Helium

NASA Astrophysics Data System (ADS)

McColgan, Patrick T.; Meraki, Adil; Boltnev, Roman E.; Lee, David M.; Khmelenko, Vladimir V.

2017-04-01

We studied optical and electron spin resonance spectra during destruction of porous structures formed by nitrogen-rare gas (RG) nanoclusters in bulk superfluid helium containing high concentrations of stabilized nitrogen atoms. Samples were created by injecting products of a radio frequency discharge of nitrogen-rare gas-helium gas mixtures into bulk superfluid helium. These samples have a high energy density allowing the study of energy release in chemical processes inside of nanocluster aggregates. The rare gases used in the studies were neon, argon, and krypton. We also studied the effects of changing the relative concentrations between nitrogen and rare gas on thermoluminescence spectra during destruction of the samples. At the beginning of the destructions, α -group of nitrogen atoms, Vegard-Kaplan bands of N_2 molecules, and β -group of O atoms were observed. The final destruction of the samples were characterized by a series bright flashes. Spectra obtained during these flashes contain M- and β -bands of NO molecules, the intensities of which depend on the concentration of molecular nitrogen in the gas mixture as well as the type of rare gas present in the gas mixture.

Nitrogen dynamics in a tidal river zone influenced by highly urbanization, western Japan

NASA Astrophysics Data System (ADS)

Saito, M.; Onodera, S. I.; Shimizu, Y.; Maruyama, Y.; Jin, G.; Aritomi, D.

2014-12-01

Tidal river and estuary are the transition zone between freshwater and seawater with high biological production. These areas have characteristics of water level fluctuation which causes surface water-groundwater interaction and the associated change in dynamics of nitrogen. Generally in coastal megacities, severe groundwater depression and high contaminants load influence on the environment of tidal river. However, these effects on the nitrogen dynamics and its load from a river to sea have not been fully evaluated in previous studies. Therefore, we aimed to clarify the characteristics of the nitrogen dynamics with the surface water-groundwater interaction in the tidal river zone of Osaka metropolitan city, western Japan. We conducted the field survey from the river mouth to the 7km upstream area of Yamato River, which has a length of 68km and a watershed area of 1,070 km2. Spatial variations in radon (222Rn) concentrations and the difference of hydraulic potential between river waters and the pore waters suggest that the groundwater discharges to the river channel in the upstream area. In contrast, the river water recharged into the groundwater near the river mouth area. It may be caused by the lowering of groundwater level associated with the excess abstraction in the urban area. The spatial and temporal variations in nutrient concentration indicate that nitrate-nitrogen (NO3-N) concentration changed temporally and it was negatively correlated with dissolved organic nitrogen (DON) concentration. Based on the mass balance estimation in winter and summer periods, nitrogen was removed in tidal river zone in both periods which was estimated to be about 10 % of total nitrogen (TN) load from the upstream. However, dissolved inorganic nitrogen (DIN) and DON was re-produced in winter and summer periods, respectively. NO3-N concentrations were negatively correlated with velocity of river water, which suggests the progress of denitrification in the tidal river zone under low discharge condition. Nitrogen and oxygen stable isotope ratios (δ15N, δ18O) of nitrate (NO3-) suggests the possibility of nitrification progress in the winter periods.

Friction and wear of plasma-deposited diamond films

NASA Technical Reports Server (NTRS)

Miyoshi, Kazuhisa; Wu, Richard L. C.; Garscadden, Alan; Barnes, Paul N.; Jackson, Howard E.

1993-01-01

Reciprocating sliding friction experiments in humid air and in dry nitrogen and unidirectional sliding friction experiments in ultrahigh vacuum were conducted with a natural diamond pin in contact with microwave-plasma-deposited diamond films. Diamond films with a surface roughness (R rms) ranging from 15 to 160 nm were produced by microwave-plasma-assisted chemical vapor deposition. In humid air and in dry nitrogen, abrasion occurred when the diamond pin made grooves in the surfaces of diamond films, and thus the initial coefficients of friction increased with increasing initial surface roughness. The equilibrium coefficients of friction were independent of the initial surface roughness of the diamond films. In vacuum the friction for diamond films contacting a diamond pin arose primarily from adhesion between the sliding surfaces. In these cases, the initial and equilibrium coefficients of friction were independent of the initial surface roughness of the diamond films. The equilibrium coefficients of friction were 0.02 to 0.04 in humid air and in dry nitrogen, but 1.5 to 1.8 in vacuum. The wear factor of the diamond films depended on the initial surface roughness, regardless of environment; it increased with increasing initial surface roughness. The wear factors were considerably higher in vacuum than in humid air and in dry nitrogen.

Soot Surface Oxidation in Laminar Hydrocarbon/Air Diffusion Flames at Atmospheric Pressure. Appendix I

NASA Technical Reports Server (NTRS)

Xu, F.; El-Leathy, A. M.; Kim, C. H.; Faeth, G. M.; Yuan, Z.-G. (Technical Monitor); Urban, D. L. (Technical Monitor); Yuan, Z.-G. (Technical Monitor)

2003-01-01

Soot surface oxidation was studied experimentally in laminar hydrocarbon/air diffusion flames at atmospheric pressure. Measurements were carried out along the axes of round fuel jets burning in coflowing dry air considering acetylene-nitrogen, ethylene, propyiene-nitrogen, propane and acetylene-benzene-nitrogen in the fuel stream. Measurements were limited to the initial stages of soot oxidation (carbon consumption less than 70%) where soot oxidation occurs at the surface of primary soot particles. The following properties were measured as a function of distance above the burner exit: soot concentrations by deconvoluted laser extinction, soot temperatures by deconvoluted multiline emission, soot structure by thermophoretic sampling and analysis using Transmission Electron Microscopy (TEM), concentrations of major stable gas species (N2, H2O, H2, O2, CO, CO2, CH4, C2H2, C2H6, C3H6, C3H8, and C6H6) by sampling and gas chromatography, concentrations of some radical species (H, OH, O) by deconvoluted Li/LiOH atomic absorption and flow velocities by laser velocimetry. For present test conditions, it was found that soot surface oxidation rates were not affected by fuel type, that direct rates of soot surface oxidation by O2 estimated from Nagle and Strickland-Constable (1962) were small compared to observed soot surface oxidation rates because soot surface oxidation was completed near the flame sheet where O2 concentrations were less than 3% by volume, and that soot surface oxidation rates were described by the OH soot surface oxidation mechanism with a collision efficiency of 0.14 and an uncertainty (95% confidence) of +/- 0.04 when allowing for direct soot surface oxidation by O2, which is in reasonably good agreement with earlier observations of soot surface oxidation rates in both premixed and diffusion flames at atmospheric pressure.

Global patterns of foliar nitrogen isotopes and their relationships with climate, mycorrhizal fungi, foliar nutrient concentrations, and nitrogen availability

Treesearch

Joseph M. Craine; Andrew J. Elmore; Marcos P. M. Aidar; Mercedes Bustamante; Todd E. Dawson; Erik A. Hobbie; Ansgar Kahmen; Michelle C. Mack; Kendra K. McLauchlan; Anders Michelsen; Gabriela Nardoto; Linda H. Pardo; Josep Penuelas; Peter B. Reich; Edward A.G. Schuur; William D. Stock; Pamela H. Templer; Ross A. Virginia; Jeffrey M. Welker; Ian J. Wright

2009-01-01

Ratios of nitrogen (N) isotopes in leaves could elucidate underlying patterns of N cycling across ecological gradients. To better understand global-scale patterns of N cycling, we compiled data on foliar N isotope ratios, foliar N concentrations, mycorrhizal type and climate for over 11 000 plants worldwide. Global-scale comparisons of other components of the N cycle...

Biogeochemistry and nitrogen cycling in an Arctic, volcanic ecosystem

NASA Astrophysics Data System (ADS)

Fogel, M. L.; Benning, L.; Conrad, P. G.; Eigenbrode, J.; Starke, V.

2007-12-01

As part of a study on Mars Analogue environments, the biogeochemistry of Sverrefjellet Volcano, Bocfjorden, Svalbard, was conducted and compared to surrounding glacial, thermal spring, and sedimentary environments. An understanding of how nitrogen might be distributed in a landscape that had extinct or very cold adapted, slow- growing extant organisms should be useful for detecting unknown life forms. From high elevations (900 m) to the base of the volcano (sea level), soil and rock ammonium concentrations were uniformly low, typically less than 1- 3 micrograms per gm of rock or soil. In weathered volcanic soils, reduced nitrogen concentrations were higher, and oxidized nitrogen concentrations lower. The opposite was found in a weathered Devonian sedimentary soil. Plants and lichens growing on volcanic soils have an unusually wide range in N isotopic compositions from -5 to +12‰, a range rarely measured in temperate ecosystems. Nitrogen contents and isotopic compositions of volcanic soils and rocks were strongly influenced by the presence or absence of terrestrial herbivores or marine avifauna with higher concentrations of N and elevated N isotopic compositions occurring as patches in areas immediately influenced by reindeer, Arctic fox ( Alopex lagopus), and marine birds. Because of the extreme conditions in this area, ephemeral deposition of herbivore feces results in a direct and immediate N pulses into the ecosystem. The lateral extent and distribution of marine- derived nitrogen was measured on a landscape scale surrounding an active fox den. Nitrogen was tracked from the bones of marine birds to soil to vegetation. Because of extreme cold, slow biological rates and nitrogen cycling, a mosaic of N patterns develops on the landscape scale.

Evaluation of hydrologic conditions and nitrate concentrations in the Rio Nigua de Salinas alluvial fan aquifer, Salinas, Puerto Rico, 2002-03

USGS Publications Warehouse

Rodriguez, Jose M.

2006-01-01

A ground-water quality study to define the potential sources and concentration of nitrate in the Rio Nigua de Salinas alluvial fan aquifer was conducted between January 2002 and March 2003. The study area covers about 3,600 hectares of the coastal plain within the municipality of Salinas in southern Puerto Rico, extending from the foothills to the Caribbean Sea. Agriculture is the principal land use and includes cultivation of diverse crops, turf grass, bioengineered crops for seed production, and commercial poultry farms. Ground-water withdrawal in the alluvial fan was estimated to be about 43,500 cubic meters per day, of which 49 percent was withdrawn for agriculture, 42 percent for public supply, and 9 percent for industrial use. Ground-water flow in the study area was primarily to the south and toward a cone of depression within the south-central part of the alluvial fan. The presence of that cone of depression and a smaller one located in the northeastern quadrant of the study area may contribute to the increase in nitrate concentration within a total area of about 545 hectares by 'recycling' ground water used for irrigation of cultivated lands. In an area that covers about 405 hectares near the center of the Salinas alluvial fan, nitrate concentrations increased from 0.9 to 6.7 milligrams per liter as nitrogen in 1986 to 8 to 12 milligrams per liter as nitrogen in 2002. Principal sources of nitrate in the study area are fertilizers (used in the cultivated farmlands) and poultry farm wastes. The highest nitrogen concentrations were found at poultry farms in the foothills area. In the area of disposed poultry farm wastes, nitrate concentrations in ground water ranged from 25 to 77 milligrams per liter as nitrogen. Analyses for the stable isotope ratios of nitrogen-15/nitrogen-14 in nitrate were used to distinguish the source of nitrate in the coastal plain alluvial fan aquifer. Potential nitrate loads from areas under cultivation were estimated for the principal crops in the area. The load estimates ranged from 18 kilograms per hectare per year as nitrogen for sorghum crops to 430 kilograms per hectare per year as nitrogen for turf-grass farms. Potential nitrate load from poultry farm wastes and from communities with septic tanks were estimated at about 580 and 47 kilograms per hectare per year as nitrogen, respectively. Results obtained from the analyses of the stable isotope ratios of nitrogen-15/nitrogen-14 in nitrate samples indicated that the high nitrate concentrations are from poultry wastes near the foothills, whereas artificial fertilizers were estimated to contribute between 39 to 97 percent of the total nitrate in the central part of the alluvial fan.

Effects of aeration frequency on leachate quality and waste in simulated hybrid bioreactor landfills.

PubMed

Ko, Jae Hac; Ma, Zeyu; Jin, Xiao; Xu, Qiyong

2016-12-01

Research has been conducted to investigate the effects of daily aeration frequency on leachate quality and waste settlement in simulated hybrid landfill bioreactors. Four laboratory-scale reactors were constructed and operated for about 10 months to simulate different bioreactor operations, including one anaerobic bioreactor and three hybrid bioreactors with different aeration frequencies (one, two, and four times per day). Chemical oxygen demand (COD) and biochemical oxygen demand (BOD 5 ) reduced more than 96% of the initial concentrations in all aerated bioreactors. The differences of COD and BOD 5 reductions among tested aeration frequencies were relatively small. For ammonia nitrogen, the higher aeration frequency (two or four times per day) resulted in the quicker reduction. Overall, the concentrations of heavy metals (Cr, Co, Cu, Mn, Ni, and Zn) decreased over time except Cd and Pb. The reduction of redox-sensitive metal concentrations (Mn, Co, Ni, and Cu) was greater in aerated bioreactors than in anaerobic bioreactor. Settlement of municipal solid waste (MSW) was enhanced with higher frequency of aeration events (four times per day). In recent years, hybird bioreactor landfill technology has gained a lot of attention. Appropriate aeration rate is crucial for hybrid bioreactor operation, but few studies have been done and different results were obtained. Research was conducted to investigate the effects of daily aeration frequency on leachate quality and waste settlement. Results indicated that aeration can effectively accelerate waste stabilization and remove organic carbon concentration and total nitrogen in the leachate.

The effect of formaldehyde and nitrogen-containing compounds on the size and volume of aerosol particles

NASA Astrophysics Data System (ADS)

Millage, K.; Galloway, M. M.; De Haan, D. O.

2012-12-01

Atmospheric aerosol can interact with clouds in many ways, often resulting in the redistribution or absorption of solar energy or changes in precipitation efficiency. Secondary organic aerosol (SOA) in particular has been linked to climate change and a reduction in the number and size of cloud particles. The reactions of nitrogen containing compounds (primary amines, amino acids and ammonium sulfate) with carbonyl compounds (such as formaldehyde and glycolaldehyde) are potential sources of SOA. Aerosol containing formaldehyde and nitrogen-containing compounds (glycine, methylamine, arginine, or ammonium sulfate) was generated from buffered solutions (pH 5.4) using a nebulizer. The aerosol was then equilibrated into a chamber containing humid air (82-84% RH), and particle sizes were measured using a SMPS system over a period of 1 hour in order to examine how the size and volume of the aerosol particles changed. Formaldehyde concentrations were varied over multiple experiments. Arginine displayed a trend of increasing relative particle size with increasing formaldehyde concentration. Ammonium sulfate and formaldehyde displayed a decrease in relative particle sizes from 0:1 to 2:1 ratios of formaldehyde to ammonium sulfate, but then an increase in relative particle sizes with increasing amounts of formaldehyde. Similarly, glycine and methylamine initially displayed decreasing relative particle sizes, until reaching a 1:1 ratio of each to formaldehyde at which point the relative particle sizes steadily increased. These effects were likely caused by the evaporation of first-generation imine products.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Scott, Nicole M.; Hess, Matthias; Bouskill, Nick J.

During hydrocarbon exposure, the composition and functional dynamics of marine microbial communities are altered, favoring bacteria that can utilize this rich carbon source. Initial exposure of high levels of hydrocarbons in aerobic surface sediments can enrich growth of heterotrophic microorganisms having hydrocarbon degradation capacity. As a result, there can be a localized reduction in oxygen potential within the surface layer of marine sediments causing anaerobic zones. We hypothesized that increasing exposure to elevated hydrocarbon concentrations would positively correlate with an increase in denitrification processes and the net accumulation of dinitrogen. This hypothesis was tested by comparing the relative abundance ofmore » genes associated with nitrogen metabolism and nitrogen cycling identified in 6 metagenomes from sediments contaminated by polyaromatic hydrocarbons from the Deepwater Horizon (DWH) oil spill in the Gulf of Mexico, and 3 metagenomes from sediments associated with natural oil seeps in the Santa Barbara Channel. An additional 8 metagenomes from uncontaminated sediments from the Gulf of Mexico were analyzed for comparison. We predicted relative changes in metabolite turnover as a function of the differential microbial gene abundances, which showed predicted accumulation of metabolites associated with denitrification processes, including anammox, in the contaminated samples compared to uncontaminated sediments, with the magnitude of this change being positively correlated to the hydrocarbon concentration and exposure duration. Furthermore, these data highlight the potential impact of hydrocarbon inputs on N cycling processes in marine sediments and provide information relevant for system scale models of nitrogen metabolism in affected ecosystems.« less

Effects of initial climatic conditions on growth and accumulation of fluoride and nitrogen in leaves of two tropical tree species exposed to industrial air pollution.

PubMed

Furlan, Cláudia Maria; Domingos, Marisa; Salatino, Antonio

2007-03-15

Saplings of Tibouchina pulchra and Psidium guajava, cultivated under standardized soil conditions, were placed in two sites at Cubatão (state of São Paulo, southeast Brazil) to study the effects of air pollution on growth, biomass allocation and foliar nitrogen and fluoride concentrations. Thirty-six potted plants were maintained over two periods of one year (Jul/00 to Jun/01; Dec/00 to Nov/01) at each of two experimental sites with distinct levels of air pollution: Pilões River Valley (PV) with vegetation virtually unaffected by air pollution; and Mogi River Valley (MV) severely affected by pollutants released mainly by chemical, fertilizer, iron and steel industries. For both species, saplings growing at MV showed alterations of growth and biomass allocation, as well as increased leaf concentrations of nitrogen and fluoride. Comparing both experimental periods, the one starting in winter (the driest season in Southeastern Brazil) seemed to affect the saplings more severely, the differences of the measured parameters between MV and PV being higher than in the second period. Multivariate analysis revealed two groups of data: one representing the MV and the other the PV saplings. For both species, saplings growing at MV showed differences in chemical composition, growth and biomass allocation, compared with the PV saplings. The results suggested that seasonal conditions of the first months of sapling exposure (summer or winter) modulate the intensity of responses to pollution stress.

Integrated analysis of the effects of agricultural management on nitrogen fluxes at landscape scale.

PubMed

Kros, J; Frumau, K F A; Hensen, A; de Vries, W

2011-11-01

The integrated modelling system INITIATOR was applied to a landscape in the northern part of the Netherlands to assess current nitrogen fluxes to air and water and the impact of various agricultural measures on these fluxes, using spatially explicit input data on animal numbers, land use, agricultural management, meteorology and soil. Average model results on NH(3) deposition and N concentrations in surface water appear to be comparable to observations, but the deviation can be large at local scale, despite the use of high resolution data. Evaluated measures include: air scrubbers reducing NH(3) emissions from poultry and pig housing systems, low protein feeding, reduced fertilizer amounts and low-emission stables for cattle. Low protein feeding and restrictive fertilizer application had the largest effect on both N inputs and N losses, resulting in N deposition reductions on Natura 2000 sites of 10% and 12%, respectively. Copyright © 2011 Elsevier Ltd. All rights reserved.

ZIF-8 Derived, Nitrogen-Doped Porous Electrodes of Carbon Polyhedron Particles for High-Performance Electrosorption of Salt Ions.

PubMed

Liu, Nei-Ling; Dutta, Saikat; Salunkhe, Rahul R; Ahamad, Tansir; Alshehri, Saad M; Yamauchi, Yusuke; Hou, Chia-Hung; Wu, Kevin C-W

2016-07-12

Three-dimensional (3-D) ZIF-8 derived carbon polyhedrons with high nitrogen (N) content, (denoted as NC-800) are synthesized for their application as high-performance electrodes in electrosorption of salt ions. The results showed a high specific capacitance of 160.8 F·g(-1) in 1 M NaCl at a scan rate of 5 mV·s(-1). Notably, integration of 3-D mesopores and micropores in NC-800 achieves an excellent capacitive deionization (CDI) performance. The electrosorption of salt ions at the electrical double layer is enhanced by N-doping at the edges of a hexagonal lattice of NC-800. As evidenced, when the initial NaCl solution concentration is 1 mM, the resultant NC-800 exhibits a remarkable CDI potential with a promising salt electrosorption capacity of 8.52 mg·g(-1).

ZIF-8 Derived, Nitrogen-Doped Porous Electrodes of Carbon Polyhedron Particles for High-Performance Electrosorption of Salt Ions

PubMed Central

Liu, Nei-Ling; Dutta, Saikat; Salunkhe, Rahul R.; Ahamad, Tansir; Alshehri, Saad M.; Yamauchi, Yusuke; Hou, Chia-Hung; Wu, Kevin C.-W.

2016-01-01

Three-dimensional (3-D) ZIF-8 derived carbon polyhedrons with high nitrogen (N) content, (denoted as NC-800) are synthesized for their application as high-performance electrodes in electrosorption of salt ions. The results showed a high specific capacitance of 160.8 F·g−1 in 1 M NaCl at a scan rate of 5 mV·s−1. Notably, integration of 3-D mesopores and micropores in NC-800 achieves an excellent capacitive deionization (CDI) performance. The electrosorption of salt ions at the electrical double layer is enhanced by N-doping at the edges of a hexagonal lattice of NC-800. As evidenced, when the initial NaCl solution concentration is 1 mM, the resultant NC-800 exhibits a remarkable CDI potential with a promising salt electrosorption capacity of 8.52 mg·g−1. PMID:27404086

CHEMISTRY OF FOG WATERS IN CALIFORNIA'S CENTRAL VALLEY - PART 3: CONCENTRATIONS AND SPECIATION OF ORGANIC AND INORGANIC NITROGEN. (R825433)

EPA Science Inventory

Although organic nitrogen (ON) has been found to be a ubiquitous and significant component in wet and dry deposition, almost nothing is known about its concentration or composition in fog waters. To address this gap, we have investigated the concentration and composition of ON...

Low-to-moderate nitrogen and phosphorus concentrations accelerate microbially driven litter breakdown rates

Treesearch

John S. Kominoski; Amy D. Rosemond; Jonathan P. Benstead; Vladislav Gulis; John C. Maerz; David Manning

2015-01-01

Particulate organic matter (POM) processing is an important driver of aquatic ecosystem productivity that is sensitive to nutrient enrichment and drives ecosystem carbon (C) loss. Although studies of single concentrations of nitrogen (N) or phosphorus (P) have shown effects at relatively low concentrations, responses of litter breakdown rates along gradients of low-to-...

Atmospheric carbon dioxide, irrigation, and fertilization effects on phenolic and nitrogen concentrations in loblolly pine (Pinus taeda) needles

Treesearch

Fitzgerald L. Booker; Christopher A. Maier

2001-01-01

Concentrations of total soluble phenolics, catechin, proanthocyanidins (PA), lignin and nitrogen (N) were measured in loblolly pine (Pinus taeda L.) needles exposed to either ambient CO2 concentration ([CO2]), ambient plus 175 or ambient plus 350 µmol O2 mol-1 in branch chambers...

Biodegradation of Mordant orange-1 using newly isolated strain Trichoderma harzianum RY44 and its metabolite appraisal.

PubMed

Hadibarata, Tony; Syafiuddin, Achmad; Al-Dhabaan, Fahad A; Elshikh, Mohamed Soliman; Rubiyatno

2018-05-01

Herein, we systematically reported the capability of T. harzianum RY44 for decolorization of Mordant orange-1. The fungi strains were isolated from the Universiti Teknologi Malaysia tropical rain forest. For initial screening, the decolorization was conducted using 50 strains of the fungi for 20 days incubation time and the best performance was selected. Then, the decolorization capability and fungal biomass were evaluated using different dye concentrations, namely, 0, 50, 75 and 100 ppm. Effects of the carbon sources (fructose, glucose, and galactose), nitrogen sources (ammonium nitrate, ammonium sulfate and yeast extract), surfactant (tween 80), aromatic compounds (benzoic acid, catechol and salicylic acid), and pH on the decolorization efficiency were examined. This study has found that the employed carbon sources, nitrogen sources, and aromatic compounds strongly enhance the decolorization efficiency. In addition, increasing the surfactant volume and pH generally decreased the decolorization efficiencies from 19.5 to 9.0% and 81.7 to 60.5%, respectively. In the mechanism philosophy, the present work has found that Mordant orange-1 were initially degraded by T. harzianum RY44 to benzoic acid and finally transformed into salicylic acid.

Computational Identification and Analysis of the Key Biosorbent Characteristics for the Biosorption Process of Reactive Black 5 onto Fungal Biomass

PubMed Central

Yang, Yu-Yi; Li, Ze-Li; Wang, Guan; Zhao, Xiao-Ping; Crowley, David E.; Zhao, Yu-Hua

2012-01-01

The performances of nine biosorbents derived from dead fungal biomass were investigated for their ability to remove Reactive Black 5 from aqueous solution. The biosorption data for removal of Reactive Black 5 were readily modeled using the Langmuir adsorption isotherm. Kinetic analysis based on both pseudo-second-order and Weber-Morris models indicated intraparticle diffusion was the rate limiting step for biosorption of Reactive Black 5 on to the biosorbents. Sorption capacities of the biosorbents were not correlated with the initial biosorption rates. Sensitivity analysis of the factors affecting biosorption examined by an artificial neural network model showed that pH was the most important parameter, explaining 22%, followed by nitrogen content of biosorbents (16%), initial dye concentration (15%) and carbon content of biosorbents (10%). The biosorption capacities were not proportional to surface areas of the sorbents, but were instead influenced by their chemical element composition. The main functional groups contributing to dye sorption were amine, carboxylic, and alcohol moieties. The data further suggest that differences in carbon and nitrogen contents of biosorbents may be used as a selection index for identifying effective biosorbents from dead fungal biomass. PMID:22442697

40 CFR 86.1323-2007 - Oxides of nitrogen analyzer calibration.

Code of Federal Regulations, 2011 CFR

2011-07-01

... 40 Protection of Environment 19 2011-07-01 2011-07-01 false Oxides of nitrogen analyzer... Exhaust Test Procedures § 86.1323-2007 Oxides of nitrogen analyzer calibration. This section describes the initial and periodic calibration of the chemiluminescent oxides of nitrogen analyzer. (a) Prior to...

40 CFR 86.1323-2007 - Oxides of nitrogen analyzer calibration.

Code of Federal Regulations, 2010 CFR

2010-07-01

... 40 Protection of Environment 19 2010-07-01 2010-07-01 false Oxides of nitrogen analyzer... Exhaust Test Procedures § 86.1323-2007 Oxides of nitrogen analyzer calibration. This section describes the initial and periodic calibration of the chemiluminescent oxides of nitrogen analyzer. (a) Prior to...

40 CFR 86.1323-2007 - Oxides of nitrogen analyzer calibration.

Code of Federal Regulations, 2013 CFR

2013-07-01

... 40 Protection of Environment 20 2013-07-01 2013-07-01 false Oxides of nitrogen analyzer... Exhaust Test Procedures § 86.1323-2007 Oxides of nitrogen analyzer calibration. This section describes the initial and periodic calibration of the chemiluminescent oxides of nitrogen analyzer. (a) Prior to...

40 CFR 86.1323-2007 - Oxides of nitrogen analyzer calibration.

Code of Federal Regulations, 2012 CFR

2012-07-01

... 40 Protection of Environment 20 2012-07-01 2012-07-01 false Oxides of nitrogen analyzer... Exhaust Test Procedures § 86.1323-2007 Oxides of nitrogen analyzer calibration. This section describes the initial and periodic calibration of the chemiluminescent oxides of nitrogen analyzer. (a) Prior to...

RIBBED MUSSEL NITROGEN ISOTOPE SIGNATURES REFLECT NITROGEN SOURCES IN COASTAL MARSHES

EPA Science Inventory

The stable nitrogen isotope ratio in tissue of the ribbed mussel (Geukensia demissa) was investigated as an indicator of the source of nitrogen inputs to coastal salt marshes. Initially, mussels were fed a diet of 15N-enriched algae in the laboratory to determine how the tissue n...

Fabrication of a nanometer thick nitrogen delta doped layer at the sub-surface region of (100) diamond

NASA Astrophysics Data System (ADS)

Chandran, Maneesh; Michaelson, Shaul; Saguy, Cecile; Hoffman, Alon

2016-11-01

In this letter, we report on the proof of a concept of an innovative delta doping technique to fabricate an ensemble of nitrogen vacancy centers at shallow depths in (100) diamond. A nitrogen delta doped layer with a concentration of ˜1.8 × 1020 cm-3 and a thickness of a few nanometers was produced using this method. Nitrogen delta doping was realized by producing a stable nitrogen terminated (N-terminated) diamond surface using the RF nitridation process and subsequently depositing a thin layer of diamond on the N-terminated diamond surface. The concentration of nitrogen on the N-terminated diamond surface and its stability upon exposure to chemical vapor deposition conditions are determined by x-ray photoelectron spectroscopy analysis. The SIMS profile exhibits a positive concentration gradient of 1.9 nm/decade and a negative gradient of 4.2 nm/decade. The proposed method offers a finer control on the thickness of the delta doped layer than the currently used ion implantation and delta doping techniques.

Preliminary assessment of sources of nitrogen in groundwater at a biosolids-application area near Deer Trail

USGS Publications Warehouse

Yager, Tracy J.B.; McMahon, Peter B.

2012-01-01

Concentrations of dissolved nitrite plus nitrate increased fairly steadily in samples from four shallow groundwater monitoring wells after biosolids applications to nonirrigated farmland began in 1993. The U.S. Geological Survey began a preliminary assessment of sources of nitrogen in shallow groundwater at part of the biosolids-application area near Deer Trail, Colorado, in 2005 in cooperation with the Metro Wastewater Reclamation District. Possible nitrogen sources in the area include biosolids, animal manure, inorganic fertilizer, atmospheric deposition, and geologic materials (bedrock and soil). Biosolids from the Metro Wastewater Reclamation District plant in Denver and biosolids, cow manure, geologic materials (bedrock and soil), and groundwater from the study area were sampled to measure nitrogen content and nitrogen isotopic compositions of nitrate or total nitrogen. Biosolids also were leached, and the leachates were analyzed for nitrogen content and other concentrations. Geologic materials from the study area also were sampled to determine mineralogy. Estimates of nitrogen contributed from inorganic fertilizer and atmospheric deposition were calculated from other published reports. The nitrogen information from the study indicates that each of the sources contain sufficient nitrogen to potentially affect groundwater nitrate concentrations. Natural processes can transform the nitrogen in any of the sources to nitrate in the groundwater. Load calculations indicate that animal manure, inorganic fertilizer, or atmospheric deposition could have contributed the largest nitrogen load to the study area in the 13 years before biosolids applications began, but biosolids likely contributed the largest nitrogen load to the study area in the 13 years after biosolids applications began. Various approaches provided insights into sources of nitrate in the groundwater samples from 2005. The isotopic data indicate that, of the source materials considered, biosolids and (or) animal manure were the most likely sources of nitrate in the wells at the time of sampling (2005), and that inorganic fertilizer, atmospheric deposition, and geologic materials were not substantial sources of nitrate in the wells in 2005. The large total nitrogen content of the biosolids and animal-manure samples and biosolids leachates also indicates that the biosolids and animal manure had potential to leach nitrogen and produce large dissolved nitrate concentrations in groundwater. The available data, however, could not be used to distinguish between biosolids or manure as the dominant source of nitrate in the groundwater because the nitrogen isotopic composition of the two materials is similar. Major-ion data also could not be used to distinguish between biosolids or manure as the dominant source of nitrate in the groundwater because the major-ion composition (as well as the isotopic composition) of the two materials is similar. Without additional data, chloride/bromide mass ratios do not necessarily support or refute the hypothesis that biosolids and (or) animal manure were the primary sources of nitrate in water from the study-area wells in 2005. Concentrations of water-extractable nitrate in the soil indicate that biosolids could be an important source of nitrate in the groundwater recharge. Nitrogen inventories in the soil beneath biosolids-application areas and the nitrogen-input estimates for the study area both support the comparisons of isotopic composition, which indicate that some type of human waste (such as biosolids) and (or) animal manure was the source of nitrate in groundwater sampled from the wells in 2005. The nitrogen-load estimates considered with the nitrogen isotopic data and the soil-nitrogen inventories indicate that biosolids applications likely are a major source of nitrogen to the shallow groundwater at these monitoring wells.

Tritrophic interactions between parasitoids and cereal aphids are mediated by nitrogen fertilizer.

PubMed

Aqueel, Muhammad A; Raza, Abu-bakar M; Balal, Rashad M; Shahid, Muhammad A; Mustafa, Irfan; Javaid, Muhammad M; Leather, Simon R

2015-12-01

Host plant nutritional quality can directly and indirectly affect the third trophic levels. The aphid-parasitoid relationship provides an ideal system to investigate tritrophic interactions (as the parasitoids are completely dependent for their development upon their hosts) and assess the bottom up forces operating at different concentrations of nitrogen applications. The effects of varying nitrogen fertilizer on the performance of Aphidius colemani (V.) reared on Sitobion avenae (F.) and Aphidius rhopalosiphi (D.) reared on Rhopalosiphum padi (L.) were measured. Parasitism and percent emergence of parasitoids were positively affected by nitrogen fertilizer treatments while developmental duration (egg, larval, and pupal stages) was not affected by increasing nitrogen inputs. In males and females of both parasitoid species, adult longevity increased with the increasing nitrogen fertilizer. Hind tibia length and mummy weight of both parasitoid species increased with nitrogen fertilizer concentrations, as a result of larger aphids. This study showed that nitrogen application to the soil can have important consequences for aboveground multitrophic interactions. © 2014 Institute of Zoology, Chinese Academy of Sciences.

Regulation of L-asparaginase in a Chlamydomonas species in response to ambient concentrations of combined nitrogen.

PubMed Central

Paul, J H; Cooksey, K E

1981-01-01

Cellular levels of an L-asparaginase in a Chlamydomonas species were found to be greater in nitrogen-limited batch cultures than in batch cultures grown in ample nitrogen. Cells grown in high nitrogen medium (5 mM NH4Cl) and suspended in nitrogen-free medium showed a 2- to 3.5-fold increase in activity after 24 to 48 h. This increase in activity was inhibited by cycloheximide and by the addition of high levels of combined nitrogen (5 mM NH4Cl, NaNO3, or L-asparagine), suggesting repression by ambient nitrogen levels as the mode of regulation of this enzyme. Derepressed L-asparaginase activity did not disappear in the presence of high concentrations of medium nitrogen, indicating the absence of an asparaginase-degrading system. Derepression of asparaginase by this organism was light dependent and inhibited by 3-(3',4'-dichlorophenyl)-1,1-dimethylurea suggesting a requirement for photosynthetic energy. PMID:7240099

Effect of some nitrogen compounds thermal stability of jet A

NASA Technical Reports Server (NTRS)

Antoine, A. C.

1982-01-01

The effect of known concentrations of some nitrogen containing compounds on the thermal stability of a conventional fuel, namely, Jet A was investigated. The concentration range from 0.01 to 0.1 wt% nitrogen was examined. Solutions were made containing, individually, pyrrole, indole, quinoline, pyridine, and 4 ethylpyridine at 0.01, 0.03, 0.06, and 0.1 wt% nitrogen concentrations in Jet A. The measurements were all made by using a standard ASTM test for evaluating fuel thermal oxidation behavior, namely, ASTM D3241, 'thermal oxidation stability of turbine fuels (JFTOT procedure).' Measurements were made at two temperature settings, and 'breakpoint temperatures' were determined. The results show that the pyrrole and indole solutions have breakpoint temperatures substantially lower than those of the Jet A used.

Nutrient leaching from extensive green roofs with different substrate compositions: a laboratory study.

PubMed

Zhang, Wei; Zhong, Xing; Che, Wu

2018-02-01

To investigate nutrient leaching from extensive green roofs, green roof platforms were established to investigate the effluent quantity and quality during artificial rainfall. When the influent volume reached three times the empty bed volume, for which the cumulative rainfall was around 300 mm, the effluent TP and COD concentrations of green roof platforms filled with peat soil did not tend to stabilize. For a long-term operation, the substrate depths had little significant influence on TN, TP and COD concentrations of the green roof effluents. A normalized cumulative emission process method was proposed to discuss the difference in various pollutant leaching processes. Obvious differences in the leaching process of different contaminants for green roof platforms filled with various substrates were observed. For the green roof filled with modified substrates, the nitrogen and phosphorus pollutant leaching rates were relatively high in the initial stage of green roof operation and the phosphorus leaching rate was higher than that of nitrogen. The green roof is a sink for TN, but not for TP and COD in this study. The outcomes are critical for the selection of green roof substrates and also contribute to green roof maintenance.

Optimization of culture conditions and medium composition for the production of micrococcin GO5 by Micrococcus sp. GO5.

PubMed

Kim, Mi-Hee; Kong, Yoon-Jung; Baek, Hong; Hyun, Hyung-Hwan

2006-01-02

To enhance the production of micrococcin GO5, a bacteriocin produced by Micrococcus sp. GO5, cultivation conditions and medium composition were optimized. The optimal initial pH and temperature for bacteriocin production were 7.0-9.0 and 37 degrees C, respectively. Micrococcus sp. GO5 displayed the highest micrococcin GO5 activity when grown in modified MRS medium that contained lactose or sucrose, rather than glucose, as a carbon source. The maximum bacteriocin activity was obtained in modified MRS medium containing 0.5% tryptone and 1.0% yeast extract as nitrogen sources instead of the other nitrogen sources present in MRS medium. Bacteriocin production was greatly affected by the concentration of K(2)HPO(4); strain GO5 produced eight-fold more bacteriocin in medium containing 2.0-2.5% K(2)HPO(4) than in medium containing 0.2% K(2)HPO(4). The optimal concentration of MgSO(4).7H(2)O for bacteriocin production was 0.5%. The production of micrococcin GO5 was increased 32-fold in shake flask culture and 16-fold in a bioreactor using the optimized medium (TY medium), compared with culturing in MRS medium.

40 CFR 90.318 - Oxides of nitrogen analyzer calibration.

Code of Federal Regulations, 2010 CFR

2010-07-01

... chemiluminescent oxides of nitrogen analyzer as described in this section. (b) Initial and Periodic Interference... and periodic calibration. Prior to its initial use and monthly thereafter, or within one month prior... following table). Example calibration points (%) Acceptable for calibration? 20, 30, 40, 50, 60, 70 No...

40 CFR 91.318 - Oxides of nitrogen analyzer calibration.

Code of Federal Regulations, 2011 CFR

2011-07-01

... nitrogen analyzer as described in this section. (b) Initial and periodic interference. Prior to its... is required. (c) Initial and periodic calibration. Prior to its introduction into service, and... 80 percent of the 10 to 90 percent range (64 percent) is required (see following table). Example...

40 CFR 91.318 - Oxides of nitrogen analyzer calibration.

Code of Federal Regulations, 2013 CFR

2013-07-01

... nitrogen analyzer as described in this section. (b) Initial and periodic interference. Prior to its... is required. (c) Initial and periodic calibration. Prior to its introduction into service, and... 80 percent of the 10 to 90 percent range (64 percent) is required (see following table). Example...

40 CFR 90.318 - Oxides of nitrogen analyzer calibration.

Code of Federal Regulations, 2011 CFR

2011-07-01

... chemiluminescent oxides of nitrogen analyzer as described in this section. (b) Initial and Periodic Interference... and periodic calibration. Prior to its initial use and monthly thereafter, or within one month prior... following table). Example calibration points (%) Acceptable for calibration? 20, 30, 40, 50, 60, 70 No...

40 CFR 91.318 - Oxides of nitrogen analyzer calibration.

Code of Federal Regulations, 2010 CFR

2010-07-01

... nitrogen analyzer as described in this section. (b) Initial and periodic interference. Prior to its... is required. (c) Initial and periodic calibration. Prior to its introduction into service, and... 80 percent of the 10 to 90 percent range (64 percent) is required (see following table). Example...

40 CFR 90.318 - Oxides of nitrogen analyzer calibration.

Code of Federal Regulations, 2013 CFR

2013-07-01

... chemiluminescent oxides of nitrogen analyzer as described in this section. (b) Initial and Periodic Interference... and periodic calibration. Prior to its initial use and monthly thereafter, or within one month prior... following table). Example calibration points (%) Acceptable for calibration? 20, 30, 40, 50, 60, 70 No...

Nitrogen isotopes as indicators of streamflow generation processes in a headwater forested catchment: Focusing on atmospheric NO3- contribution using δ 18O signature

NASA Astrophysics Data System (ADS)

Ohte, N.; Sebestyen, S. D.; Doctor, D. H.; Wankel, S. D.; Shanley, J. B.; Kendall, C.; Boyer, E. W.

2003-12-01

To quantify the contributions of atmospheric nitrogen deposition and mechanisms of nitrate discharge to stream, nitrogen chemistry and isotopes (δ 15N and δ 18O of NO3-) of streamwater were studied as part of an ongoing study of nutrient dynamics at the Sleepers River Research Watershed in Vermont, USA. We employed novel analytical procedures for high throughput of NO3- isotopic measurements. The denitrifier method for measurement of δ 15N and δ 18O of NO3- requires a smaller volume of water samples than previously applied methods, thus it enables fine resolution analysis of isotopes for stream, well, and soil water samples. Samples were collected throughout the spring 2003 snowmelt. Snowmelt runoff was initiated in the middle of March and peaked at the end of the month. Then, the runoff rate decreased gradually through April and May, and responded to several storm events. The highest concentration of NO3- in the stream was observed at the beginning of snowmelt (the end of March), and thereafter it declined continuously. The temporal course of NO3- discharge process during snowmelt period was divided into four phases based on changes in the relationship between runoff rate and NO3- concentration. During the earliest phase (very low runoff rate and highest NO3- concentration) isotope signatures, especially δ 18O of NO3-, indicated higher contribution of the atmospherically derived NO3-, meaning that the direct discharge from snow pack was the dominant source of NO3- to the stream. This also suggested that streamwater consisted only of a small volume of groundwater discharge and melt water of the in-stream snow pack and/or stream-covering snow pack. The δ 15N and δ 18O isotope compositions of NO3- during the middle phase of snowmelt indicated that the contribution of the NO3- generated by nitrifiers in soil increased gradually accompanied with increase of groundwater level. These detailed descriptions in the changes of NO3- discharge during snowmelt events were enabled by the dual-isotope analysis of NO3-. The fine resolution isotope analysis of NO3- in our experiment can provide advantages for elucidating the discharge mechanisms of nitrogen in forested watersheds with high atmospheric nitrogen depositions.

Water-soluble organic nitrogen in atmospheric fine particles (PM2.5) from northern California

NASA Astrophysics Data System (ADS)

Zhang, Qi; Anastasio, Cort; Jimenez-Cruz, Mike

2002-06-01

Recent studies have suggested that organic nitrogen (ON) is a ubiquitous and significant component of atmospheric dry and wet deposition, but very little is known about the concentrations and speciation of organic nitrogen in aerosol particles. In addition, while amino compounds also appear to be ubiquitous in atmospheric condensed phases, their contribution to organic nitrogen has not been previously quantified. To address these issues, we have characterized the water-soluble organic nitrogen and amino compounds in fine particles (PM2.5) collected in Davis, California, over a period of 1 year. Concentrations of water-soluble organic nitrogen (WSON) ranged from 3.1-57.8 nmol N m-3 air, peaking during winter and early spring, and typically accounted for ~20% of total nitrogen in Davis PM2.5. Assuming an average N-normalized molecular weight of 100 Da per N atom for WSON, particulate organic nitrogen had a median mass concentration of 1.6 μg m-3 air, and typically represented 18% of the total fine particle mass. The average mass of water-soluble ON in Davis PM2.5 was comparable to that of sulfate during the summer, but was significantly higher in winter. Total amino compounds (free plus combined forms) made up a significant portion of particulate organic nitrogen (median value equal to 23%), primarily due to the presence of combined amino compounds such as proteins and peptides. Total amino compounds had a median mass concentration of 290 ng m-3 air, and typically accounted for 3.3% of the total fine particle mass. These results indicate that organic nitrogen is a significant component of fine particles in northern California, and suggest that this group of compounds might play an important role in the ecological, radiative, and potential health effects of atmospheric fine particles in this region.

Osmotic phenomena in application for hyperbaric oxygen treatment.

PubMed

Babchin, A; Levich, E; Melamed M D, Y; Sivashinsky, G

2011-03-01

Hyperbaric oxygen (HBO) treatment defines the medical procedure when the patient inhales pure oxygen at elevated pressure conditions. Many diseases and all injuries are associated with a lack of oxygen in tissues, known as hypoxia. HBO provides an effective method for fast oxygen delivery in medical practice. The exact mechanism of the oxygen transport under HBO conditions is not fully identified. The objective of this article is to extend the colloid and surface science basis for the oxygen transport in HBO conditions beyond the molecular diffusion transport mechanism. At a pressure in the hyperbaric chamber of two atmospheres, the partial pressure of oxygen in the blood plasma increases 10 times. The sharp increase of oxygen concentration in the blood plasma creates a considerable concentration gradient between the oxygen dissolved in the plasma and in the tissue. The concentration gradient of oxygen as a non-electrolyte solute causes an osmotic flow of blood plasma with dissolved oxygen. In other words, the molecular diffusion transport of oxygen is supplemented by the convective diffusion raised due to the osmotic flow, accelerating the oxygen delivery from blood to tissue. A non steady state equation for non-electrolyte osmosis is solved asymptotically. The solution clearly demonstrates two modes of osmotic flow: normal osmosis, directed from lower to higher solute concentrations, and anomalous osmosis, directed from higher to lower solute concentrations. The fast delivery of oxygen from blood to tissue is explained on the basis of the strong molecular interaction between the oxygen and the tissue, causing an influx of oxygen into the tissue by convective diffusion in the anomalous osmosis process. The transport of the second gas, nitrogen, dissolved in the blood plasma, is also taken into the consideration. As the patient does not inhale nitrogen during HBO treatment, but exhales it along with oxygen and carbon dioxide, the concentration of nitrogen in blood plasma drops and the nitrogen concentration gradient becomes directed from blood to tissue. On the assumption of weak interaction between the inert nitrogen and the human tissue, normal osmosis for the nitrogen transport takes place. Thus, the directions of anomalous osmotic flow caused by the oxygen concentration gradient coincide with the directions of normal osmotic flow, caused by the nitrogen concentration gradient. This leads to the conclusion that the presence of nitrogen in the human body promotes the oxygen delivery under HBO conditions, rendering the overall success of the hyperbaric oxygen treatment procedure. 2010 Elsevier B.V. All rights reserved.

Influence of pulsed-light irradiation on the productivity and nitrogen-fixing ability of blue-green algae nostoc muscorum Ag

DOE Office of Scientific and Technical Information (OSTI.GOV)

Umarov, G.Ya.; Kuchkarova, M.A.; Maksudov, T.U.

1975-01-01

The utilization of pulsed concentrated sunlight to improve the productivity of nostoc muscorum Ag. algae was investigated. In laboratory experiments the greatest accumulation of biomass was found after 5-min irradiation; there was a 10 percent increase in nitrogen fixation. For cultivation under the open sky productivity and nitrogen fixation rose after 10- and 20-min irradiation by pulsed concentrated sunlight.

Assessment of global nitrogen pollution in rivers using an integrated biogeochemical modeling framework.

PubMed

He, Bin; Kanae, Shinjiro; Oki, Taikan; Hirabayashi, Yukiko; Yamashiki, Yosuke; Takara, Kaoru

2011-04-01

This study has analyzed the global nitrogen loading of rivers resulting from atmospheric deposition, direct discharge, and nitrogenous compounds generated by residential, industrial, and agricultural sources. Fertilizer use, population distribution, land cover, and social census data were used in this study. A terrestrial nitrogen cycle model with a 24-h time step and 0.5° spatial resolution was developed to estimate nitrogen leaching from soil layers in farmlands, grasslands, and natural lands. The N-cycle in this model includes the major processes of nitrogen fixation, nitrification, denitrification, immobilization, mineralization, leaching, and nitrogen absorption by vegetation. The previously developed Total Runoff Integrating Pathways network was used to analyze nitrogen transport from natural and anthropogenic sources through river channels, as well as the collecting and routing of nitrogen to river mouths by runoff. Model performance was evaluated through nutrient data measured at 61 locations in several major world river basins. The dissolved inorganic nitrogen concentrations calculated by the model agreed well with the observed data and demonstrate the reliability of the proposed model. The results indicate that nitrogen loading in most global rivers is proportional to the size of the river basin. Reduced nitrate leaching was predicted for basins with low population density, such as those at high latitudes or in arid regions. Nitrate concentration becomes especially high in tropical humid river basins, densely populated basins, and basins with extensive agricultural activity. On a global scale, agriculture has a significant impact on the distribution of nitrogenous compound pollution. The map of nitrate distribution indicates that serious nitrogen pollution (nitrate concentration: 10-50 mg N/L) has occurred in areas with significant agricultural activities and small precipitation surpluses. Analysis of the model uncertainty also suggests that the nitrate export in most rivers is sensitive to the amount of nitrogen leaching from agricultural lands. Copyright © 2011 Elsevier Ltd. All rights reserved.

Spatial Scale Variability of NH3 and Impacts to interpolated Concentration Grids

EPA Science Inventory

Over the past decade, reduced nitrogen (NH3, NH4) has become an important component of atmospheric nitrogen deposition due to increases in agricultural activities and reductions in oxidized sulfur and nitrogen emissions from the power sector and mobile sources. Reduced nitrogen i...

A Simple Model of Nitrogen Concentration, Throughput, and Denitrification in Estuaries

EPA Science Inventory

The Estuary Nitrogen Model (ENM) is a mass balance model that includes calculation of nitrogen losses within bays and estuaries using system flushing time. The model has been used to demonstrate the dependence of throughput and denitrification of nitrogen in bays and estuaries on...

A MODEL OF ESTUARY RESPONSE TO NITROGEN LOADING AND FRESHWATER RESIDENCE TIME

EPA Science Inventory

We have developed a deterministic model that relates average annual nitrogen loading rate and water residence time in an estuary to in-estuary nitrogen concentrations and loss rates (e.g. denitrification and incorporation in sediments), and to rates of nitrogen export across the ...

Concentrations and deposition of nitrogenous air pollutants in a ponderosa/Jeffrey pine canopy

Treesearch

Andrzej Bytnerowicz; Mark E. Fenn; Michael J. Arbaugh

1998-01-01

Nitrogenous (N) air pollutant concentrations and surface deposition of nitrate (NO3-) and ammonium (NH4+) to branches of ponderosa pine (Pinus ponderosa Dougl. ex. Laws.) seedlings were measured on a vertical transect in a mature ponderosa/Jeffrey (...

Synthesis of soybean oil-based thiol oligomers.

PubMed

Wu, Jennifer F; Fernando, Shashi; Weerasinghe, Dimuthu; Chen, Zhigang; Webster, Dean C

2011-08-22

Industrial grade soybean oil (SBO) and thiols were reacted to generate thiol-functionalized oligomers via a thermal, free radical initiated thiol-ene reaction between the SBO double bond moieties and the thiol functional groups. The effect of the reaction conditions, including thiol concentration, catalyst loading level, reaction time, and atmosphere, on the molecular weight and the conversion to the resultant soy-thiols were examined in a combinatorial high-throughput fashion using parallel synthesis, combinatorial FTIR, and rapid gel permeation chromatography (GPC). High thiol functionality and concentration, high thermal free radical catalyst concentration, long reaction time, and the use of a nitrogen reaction atmosphere were found to favor fast consumption of the SBO, and produced high molecular weight products. The thiol conversion during the reaction was inversely affected by a high thiol concentration, but was favored by a long reaction time and an air reaction atmosphere. These experimental observations were explained by the initial low affinity of the SBO and thiol, and the improved affinity between the generated soy-thiol oligomers and unreacted SBO during the reaction. The synthesized soy-thiol oligomers can be used for renewable thiol-ene UV curable materials and high molecular solids and thiourethane thermal cure materials. Copyright © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Community-weighted mean of leaf traits and divergence of wood traits predict aboveground biomass in secondary subtropical forests.

PubMed

Ali, Arshad; Yan, En-Rong; Chang, Scott X; Cheng, Jun-Yang; Liu, Xiang-Yu

2017-01-01

Subtropical forests are globally important in providing ecological goods and services, but it is not clear whether functional diversity and composition can predict aboveground biomass in such forests. We hypothesized that high aboveground biomass is associated with high functional divergence (FDvar, i.e., niche complementarity) and community-weighted mean (CWM, i.e., mass ratio; communities dominated by a single plant strategy) of trait values. Structural equation modeling was employed to determine the direct and indirect effects of stand age and the residual effects of CWM and FDvar on aboveground biomass across 31 plots in secondary forests in subtropical China. The CWM model accounted for 78, 20, 6 and 2% of the variation in aboveground biomass, nitrogen concentration in young leaf, plant height and specific leaf area of young leaf, respectively. The FDvar model explained 74, 13, 7 and 0% of the variation in aboveground biomass, plant height, twig wood density and nitrogen concentration in young leaf, respectively. The variation in aboveground biomass, CWM of leaf nitrogen concentration and specific leaf area, and FDvar of plant height, twig wood density and nitrogen concentration in young leaf explained by the joint model was 86, 20, 13, 7, 2 and 0%, respectively. Stand age had a strong positive direct effect but low indirect positive effects on aboveground biomass. Aboveground biomass was negatively related to CWM of nitrogen concentration in young leaf, but positively related to CWM of specific leaf area of young leaf and plant height, and FDvar of plant height, twig wood density and nitrogen concentration in young leaf. Leaf and wood economics spectra are decoupled in regulating the functionality of forests, communities with diverse species but high nitrogen conservative and light acquisitive strategies result in high aboveground biomass, and hence, supporting both the mass ratio and niche complementarity hypotheses in secondary subtropical forests. Copyright © 2016 Elsevier B.V. All rights reserved.

Nutrient mass balance and trends, Mobile River Basin, Alabama, Georgia, and Mississippi

USGS Publications Warehouse

Harned, D.A.; Atkins, J.B.; Harvill, J.S.

2004-01-01

A nutrient mass balance - accounting for nutrient inputs from atmospheric deposition, fertilizer, crop nitrogen fixation, and point source effluents; and nutrient outputs, including crop harvest and storage - was calculated for 18 subbasins in the Mobile River Basin, and trends (1970 to 1997) were evaluated as part of the U.S. Geological Survey National Water Quality Assessment (NAWQA) Program. Agricultural nonpoint nitrogen and phosphorus sources and urban nonpoint nitrogen sources are the most important factors associated with nutrients in this system. More than 30 percent of nitrogen yield in two basins and phosphorus yield in eight basins can be attributed to urban point source nutrient inputs. The total nitrogen yield (1.3 tons per square mile per year) for the Tombigbee River, which drains a greater percentage of agricultural (row crop) land use, was larger than the total nitrogen yield (0.99 tons per square mile per year) for the Alabama River. Decreasing trends of total nitrogen concentrations in the Tombigbee and Alabama Rivers indicate that a reduction occurred from 1975 to 1997 in the nitrogen contributions to Mobile Bay from the Mobile River. Nitrogen concentrations also decreased (1980 to 1995) in the Black Warrior River, one of the major tributaries to the Tombigbee River. Total phosphorus concentrations increased from 1970 to 1996 at three urban influenced sites on the Etowah River in Georgia. Multiple regression analysis indicates a distinct association between water quality in the streams of the Mobile River drainage basin and agricultural activities in the basin.

Numerical modelling of emissions of nitrogen oxides in solid fuel combustion.

PubMed

Bešenić, Tibor; Mikulčić, Hrvoje; Vujanović, Milan; Duić, Neven

2018-06-01

Among the combustion products, nitrogen oxides are one of the main contributors to a negative impact on the environment, participating in harmful processes such as tropospheric ozone and acid rains production. The main source of emissions of nitrogen oxides is the human combustion of fossil fuels. Their formation models are investigated and implemented with the goal of obtaining a tool for studying the nitrogen-containing pollutant production. In this work, numerical simulation of solid fuel combustion was carried out on a three-dimensional model of a drop tube furnace by using the commercial software FIRE. It was used for simulating turbulent fluid flow and temperature field, concentrations of the reactants and products, as well as the fluid-particles interaction by numerically solving the integro-differential equations describing these processes. Chemical reactions mechanisms for the formation of nitrogen oxides were implemented by the user functions. To achieve reasonable calculation times for running the simulations, as well as efficient coupling with the turbulent mixing process, the nitrogen scheme is limited to sufficiently few homogeneous reactions and species. Turbulent fluctuations that affect the reaction rates of nitrogen oxides' concentration are modelled by probability density function approach. Results of the implemented model for nitrogen oxides' formation from coal and biomass are compared to the experimental data. Temperature, burnout and nitrogen oxides' concentration profiles are compared, showing satisfactory agreement. The new model allows the simulation of pollutant formation in the real-world applications. Copyright © 2018 Elsevier Ltd. All rights reserved.

[Effects of nitrogen preserving agent on composting process and nitrogen loss of Eichhornia crassipes].

PubMed

Li, Sen; Luo, Xue Mei; Tu, Wei Guo; Fan, Hua; Gou, Xiao Lin; DU, Yu Long; Li, Ling; Wang, Qiong Yao

2017-04-18

To study the effects of nitrogen preserving agent (NPA) on composting process and nitrogen loss of Eichhornia crassipes, an aerobic composting was conducted for 35 days using four treatments. The NPA was prepared by mixing ferrous sulfate, humic acid sodium, and superphosphate (M:M:M=75:20:5). Four treatments were included with different mass ratios of NPA, including 0% (CK), 1% (PN1), 2% (PN2), and 3% (PN3). The physical and chemical properties, N fraction concentrations, ammonia volatilization, and N loss rates were measured and explored during composting process. The results showed that the pile temperature of NPA treatments were higher than that of CK in thermophillic period, however their water contents were significantly (P＜0.05) lower than that in CK in cooling period. At the end of composting, the concentrations of total nitrogen and organic nitrogen increased significantly in NPA treatments (P＜0.05), and their highest concentrations in the PN3 treatment were 16.3% and 13.2% higher than those in CK, respectively. The ammonia volatilization losses of PN1, PN2 and PN3 treatments were 25.9%, 31.5% and 42.4% lower than that of CK, respectively, however, their nitrogen fixation rates reached 31.3%, 40.7% and 72.2% respectively. Therefore, adding NPA could accelerate start-up speed, shorten composting time, and also could effectively reduce ammonia volatilizations and nitrogen loss in the composting process of E. crassipes. Therefore, PN3 showed the best effects of nitrogen preserving.

Urban groundwater as a possible nutrient source for an estuarine benthic algal bloom

NASA Astrophysics Data System (ADS)

Sewell, P. L.

1982-11-01

The Peel Inlet in Western Australia was used to study the cause of eutrophic conditions in an estuary. In addition to large quantities of nitrogen and phosphorus (at low concentrations) entering the inlet from rivers and drains from agricultural areas, the urban contribution via groundwater was identified. The average nitrogen concentration of urban groundwater under an area serviced with septic tank systems was 12 parts 10 -6. Because of the nature of the soils, very few groundwater samples contained appreciable phosphorus concentrations. However, one area close to the inlet had semiconfined groundwaters with nitrogen and phosphorus concentrations as high as 100 and 0·4 parts 10 -6 respectively. An obsolete dumping site for human excreta was also identified near the urban area, and this is suspected of having contributed to very high concentrations of nitrogen and phosphorus in groundwater which may have already reached the estuary and caused excessive algal growth. Groundwater contours showed the potential for groundwater movement from part of the urban area and also from the obsolete dumping site.

The impact of an underground cut-off wall on nutrient dynamics in groundwater in the lower Wang River watershed, China.

PubMed

Kang, Pingping; Xu, Shiguo

2017-03-01

Underground cut-off walls in coastal regions are mainly used to prevent saltwater intrusion, but their impact on nutrient dynamics in groundwater is not clear. In this study, a combined analysis of multiple isotopes ([Formula: see text]) and nitrogen and phosphorus concentrations is used in order to assess the impact of the underground cut-off walls on the nutrient dynamics in groundwater in the lower Wang River watershed, China. Compared with the nitrogen and phosphorus concentrations in groundwater downstream of the underground cut-off walls, high [Formula: see text] and total dissolved nitrogen concentrations and similar concentration levels of [Formula: see text] and total dissolved phosphorus are found in groundwater upstream of the underground cut-off walls. The isotopic data indicated the probable occurrence of denitrification and nitrification processes in groundwater upstream, whereas the fingerprint of these processes was not shown in groundwater downstream. The management of fertilizer application is critical to control nitrogen concentrations in groundwater restricted by the underground cut-off walls.

Interference of oxygen, carbon dioxide, and water vapor on the analysis for oxides of nitrogen by chemiluminescence

NASA Technical Reports Server (NTRS)

Maahs, H. G.

1975-01-01

The interference of small concentrations (less than 4 percent by volume) of oxygen, carbon dioxide, and water vapor on the analysis for oxides of nitrogen by chemiluminescence was measured. The sample gas consisted primarily of nitrogen, with less than 100 parts per million concentration of nitric oxide, and with small concentrations of oxygen, carbon dioxide, and water vapor added. Results obtained under these conditions indicate that although oxygen does not measurably affect the analysis for nitric oxide, the presence of carbon dioxide and water vapor causes the indicated nitric oxide concentration to be too low. An interference factor - defined as the percentage change in indicated nitric oxide concentration (relative to the true nitric oxide concentration) divided by the percent interfering gas present - was determined for carbon dioxide to be -0.60 + or - 0.04 and for water vapor to be -2.1 + or - 0.3.

An improved biofilter to control the dissolved organic nitrogen concentration during drinking water treatment.

PubMed

Zhang, Huining; Gu, Li; Liu, Bing; Gan, Huihui; Zhang, Kefeng; Jin, Huixia; Yu, Xin

2016-09-01

Dissolved organic nitrogen (DON) is a key precursor of numerous disinfection by-products (DBPs), especially nitrogenous DBPs (N-DBPs) formed during disinfection in drinking water treatment. To effectively control DBPs, reduction of the DON concentration before the disinfection process is critical. Traditional biofilters can increase the DON concentration in the effluent, so an improved biofilter is needed. In this study, an improved biofilter was set up with two-layer columns using activated carbon and quartz sand under different influent patterns. Compared with the single-layer filter, the two-layer biofilter controlled the DON concentration more efficiently. The two-point influent biofilter controlled the DON concentration more effectively than the single-point influent biofilter. The improved biofilter resulted in an environment (including matrix, DO, and pH) suitable for microbial growth. Along the depth of the biofilter column, the environment affected the microbial biomass and microbial activity and thus affected the DON concentration.

Optimization of free ammonia concentration for nitrite accumulation in shortcut biological nitrogen removal process.

PubMed

Chung, Jinwook; Shim, Hojae; Park, Seong-Jun; Kim, Seung-Jin; Bae, Wookeun

2006-03-01

A shortcut biological nitrogen removal (SBNR) utilizes the concept of a direct conversion of ammonium to nitrite and then to nitrogen gas. A successful SBNR requires accumulation of nitrite in the system and inhibition of the activity of nitrite oxidizers. A high concentration of free ammonia (FA) inhibits nitrite oxidizers, but unfortunately decreases the ammonium removal rate as well. Therefore, the optimal range of FA concentration is necessary not only to stabilize nitrite accumulation but also to achieve maximum ammonium removal. In order to derive such optimal FA concentrations, the specific substrate utilization rates of ammonium and nitrite oxidizers were measured. The optimal FA concentration range appeared to be 5-10 mg/L for the adapted sludge. The simulated results from the modified inhibition model expressed by FA and ammonium/nitrite concentrations were shown very similar to the experimental results.

Effect of two doses of urea foliar application on leaves and grape nitrogen composition during two vintages.

PubMed

Pérez-Álvarez, Eva P; Garde-Cerdán, Teresa; García-Escudero, Enrique; Martínez-Vidaurre, José María

2017-06-01

Nitrogen affects grapevine growth and also yeast metabolism, which have a direct influence on fermentation kinetics and the formation of different volatile compounds. Throughout the grapevine cycle, soil nitrogen availability and grape nitrogen composition can vary because of different factors. Nitrogen foliar applications can contribute toward enhancing grapevine nitrogen status and minimize the problem of leaching that traditional nitrogen-soil applications can provoke. The present study aimed to evaluate the influence of urea foliar applications on grapevine nitrogen status and grape amino acid content. Accordingly, two different doses of urea were applied over the leaves of a 'Tempranillo' vineyard. The highest urea doses affected nitrogen content on blade leaf tissues after veraison. Must amino acid profiles were modified by urea application and some of the compounds increased their concentrations. The effect of year on the increase of must total amino acid concentrations was more important than the effect of the doses applied. Urea foliar applications can be an interesting tool for decreasing grapevine nitrogen deficiencies. This method of nitrogen implementation in the vineyard could avoid sluggish fermentation problems during winemaking, enhance must nitrogen composition, and contribute to improving wine quality. © 2016 Society of Chemical Industry. © 2016 Society of Chemical Industry.

21 CFR 177.1520 - Olefin polymers.

Code of Federal Regulations, 2011 CFR

2011-04-01

... by reaction with fumaric acid in the absence of free radical initiators. Such polymers shall contain... acid in the absence of free radical initiators. Such polymers shall contain not more than 4.5 percent... tube for preheated, oxygen-free nitrogen, and an outlet tube located 1 inch off center. Nitrogen is fed...

21 CFR 177.1520 - Olefin polymers.

Code of Federal Regulations, 2010 CFR

2010-04-01

... by reaction with fumaric acid in the absence of free radical initiators. Such polymers shall contain... acid in the absence of free radical initiators. Such polymers shall contain not more than 4.5 percent... tube for preheated, oxygen-free nitrogen, and an outlet tube located 1 inch off center. Nitrogen is fed...

78 FR 27374 - Workshop To Review Initial Draft Materials for the Nitrogen Oxides (NOX

Federal Register 2010, 2011, 2012, 2013, 2014

2013-05-10

... materials that will inform the development of the NO X Integrated Science Assessment (ISA) for health... ENVIRONMENTAL PROTECTION AGENCY [FRL-9812-6] Workshop To Review Initial Draft Materials for the Nitrogen Oxides (NO X ) Integrated Science Assessment (ISA) for Health Effects AGENCY: Environmental...

Nitrogen assimilation in denitrifier Bacillus azotoformans LMG 9581T.

PubMed

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).

Long-term trends in submersed aquatic vegetation (SAV) in Chesapeake Bay, USA, related to water quality

USGS Publications Warehouse

Orth, Robert J.; Williams, Michael R.; Marion, Scott R.; Wilcox, David J.; Carruthers, Tim J.B.; Moore, Kenneth A.; Kemp, W.M.; Dennison, William C.; Rybicki, Nancy B.; Peter Bergstrom,; Batiuk, Richard A.

2010-01-01

Chesapeake Bay supports a diverse assemblage of marine and freshwater species of submersed aquatic vegetation (SAV) whose broad distributions are generally constrained by salinity. An annual aerial SAV monitoring program and a bi-monthly to monthly water quality monitoring program have been conducted throughout Chesapeake Bay since 1984. We performed an analysis of SAV abundance and up to 22 environmental variables potentially influencing SAV growth and abundance (1984-2006). Historically, SAV abundance has changed dramatically in Chesapeake Bay, and since 1984, when SAV abundance was at historic low levels, SAV has exhibited complex changes including long-term (decadal) increases and decreases, as well as some large, single-year changes. Chesapeake Bay SAV was grouped into three broad-scale community-types based on salinity regime, each with their own distinct group of species, and detailed analyses were conducted on these three community-types as well as on seven distinct case-study areas spanning the three salinity regimes. Different trends in SAVabundance were evident in the different salinity regimes. SAV abundance has (a) continually increased in the low-salinity region; (b) increased initially in the medium-salinity region, followed by fluctuating abundances; and (c) increased initially in the high-salinity region, followed by a subsequent decline. In all areas, consistent negative correlations between measures of SAV abundance and nitrogen loads or concentrations suggest that meadows are responsive to changes in inputs of nitrogen. For smaller case-study areas, different trends in SAV abundance were also noted including correlations to water clarity in high-salinity case-study areas, but nitrogen was highly correlated in all areas. Current maximum SAV coverage for almost all areas remain below restoration targets, indicating that SAV abundance and associated ecosystem services are currently limited by continued poor water quality, and specifically high nutrient concentrations, within Chesapeake Bay. The nutrient reductions noted in some tributaries, which were highly correlated to increases in SAV abundance, suggest management activities have already contributed to SAV increases in some areas, but the strong negative correlation throughout the Chesapeake Bay between nitrogen and SAV abundance also suggests that further nutrient reductions will be necessary for SAV to attain or exceed restoration targets throughout the bay.

Effectiveness of a stormwater collection and detention system for reducing constituent loads from bridge runoff in Pinellas County, Florida

USGS Publications Warehouse

Stoker, Y.E.

1996-01-01

The quantity and quality of stormwater runoff from the Bayside Bridge were evaluated to determine the effectiveness of the stormwater collection and detention pond system of the bridge in reducing constituent loads to Old Tampa Bay. Water-quality samples of stormwater runoff from the bridge and outflow from the detention pond were collected during and after selected storms. These samples were used to compute loads for selected constituents. Stormwater on the Bayside Bridge drained rapidly during rain events. The volume of stormwater runoff from 24 storms measured during the study ranged from 4,086 to 103,705 cubic feet. Storms were most frequent during July through September and were least frequent from February through May. Concentrations of most constituents in stormwater runoff before the bridge opened to traffic were less than or equal to concentrations measured after the bridge was opened to traffic. However, concentrations of arsenic in the outflow from the detention pond generally were greater before the bridge opened than concentrations after, and concentrations of orthophosphorus in the stormwater runoff and outflow from the pond were greater before the bridge opened than during over half the sampled storms after the bridge opened. Concentrations of most constituents measured in stormwater runoff from the bridge were greatest at the beginning of the storm and decreased as the storm continued. Variations in suspended solids, nutrients, and trace element concentrations were not always concurrent with each other. The source of the measured constituent (rainfall or road debris) and the phase of the constituent (suspended or dissolved) probably affected the timing of concentration changes. The quality of stormwater runoff from the Bayside Bridge varied with total runoff volume, with the length of the dry period before the storm, and with season. Average concentrations of suspended solids, ammonia plus organic nitrogen, nitrite plus nitrate nitrogen, orthophosphorus, phosphorus, total organic carbon, aluminum, arsenic, copper, and zinc in stormwater runoff generally were inversely related to runoff volume. The quality of outflow from the detention pond also varied during a storm event and with season. Maximum concentrations generally occurred near the beginning of a storm, and decreased as the storm continued. Maximum concentrations of many constituents occurred in June and July 1995. During the summer months, pH exceeded 9.0 while inorganic nitrogen concentrations were very low. These high pH values and low inorganic nitrogen concentrations are most likely associated with photosynthesis by algae or aquatic plants in the pond. Concentrations of nitrogen, phosphorus, and nickel in stormwater runoff were correlated with total organic carbon concentrations. Concentrations of chromium, copper, iron, nickel, lead, and zinc in stormwater runoff were correlated with aluminum concentrations. The source of these metals is probably the bridge materials and metallic debris from vehicles. The northern detention pond system of the Bayside Bridge effectively reduced concentrations of suspended solids, ammonia nitrogen, nitrite plus nitrate nitrogen, phosphorus, aluminum, cadmium, chromium, copper, iron, lead, nickel, and zinc in stormwater runoff before water discharged from the pond. However, concentrations of ammonia plus organic nitrogen, organic carbon, arsenic, and values for alkalinity, pH, and specific conductance generally were greater in outflow from the pond than in stormwater runoff from the bridge. Stormwater runoff and pond outflow for three storm events were evaluated to determine the effectiveness of the detention pond system in removing selected constituents from the stormwater runoff. Most constituents and constituent loads were reduced in the outflow from the pond. Suspended solids loads were reduced about 30 to 45 percent, inorganic nitrogen loads were reduced by about 60 to 90 percent, and loads of most trace elements

LANDSCAPE CHARACTERISTICS AND HIGH STREAM NITROGEN IN THE OREGON COAST RANGE: RED ALDER COMPLICATES USE OF NUTRIENT CRITERIA

EPA Science Inventory

Stream nitrogen concentrations are variable and often high in the Oregon Coast Range, uncharacteristic for a predominantly forested region. We compiled stream nitrogen data and GIS-derived landscape characteristics in order to examine variation in nitrogen across the region. In s...

Nitrogen dioxide detection

DOEpatents

Sinha, Dipen N.; Agnew, Stephen F.; Christensen, William H.

1993-01-01

Method and apparatus for detecting the presence of gaseous nitrogen dioxide and determining the amount of gas which is present. Though polystyrene is normally an insulator, it becomes electrically conductive in the presence of nitrogen dioxide. Conductance or resistance of a polystyrene sensing element is related to the concentration of nitrogen dioxide at the sensing element.

Effects of Water and Nitrogen Availability on Nitrogen Contribution by the Legume, Lupinus argenteus Pursh.

USDA-ARS?s Scientific Manuscript database

Nitrogen-fixing species contribute to ecosystem nitrogen budgets, but background resource levels influence nodulation, fixation, and plant growth. We conducted a greenhouse experiment to examine the separate and interacting effects of water and N availability on biomass production, tissue N concentr...

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

USGS Publications Warehouse

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.

Effect of increased concentrate allotment before evening grazing on herbage intake, nitrogen utilization and rumen fermentation in dairy cows grazed on perennial ryegrass pasture.

PubMed

Ueda, Koichiro; Mitani, Tomohiro; Kondo, Seiji

2016-10-01

Two experiments were conducted to elucidate the effect of increased concentrate allotment before evening grazing on herbage intake, nitrogen utilization and rumen fermentation in dairy cows. In experiment 1, nine lactating cows were grazed in the morning and evening sessions (2.5 h each). The cows were allocated to treatments of three concentrate allotment levels before the evening grazing session by altering proportions to daily total offered; 25%, 50% and 75%. Daily herbage dry matter intake quadratically decreased with increasing the concentrate allotment levels (P < 0.05). Nitrogen utilization was similar among treatments. To investigate diurnal changes in rumen fermentation, a second experiment was conducted where six ruminally cannulated non-lactating dairy cows grazed in the morning and evening sessions (3 h each) were subjected to the same treatments as experiment 1. Total volatile fatty acid concentration in the rumen linearly increased with increasing the concentrate allotment levels throughout the pre-evening grazing session to the post-morning grazing session (P < 0.01). The results indicate that dairy cows reduce daily herbage intake but do not alter nitrogen utilization with increasing concentrate allotment before evening grazing. © 2016 Japanese Society of Animal Science. © 2016 Japanese Society of Animal Science.

Carbon Concentration and Carbon-to-Nitrogen Ratio Influence Submerged-Culture Conidiation by the Potential Bioherbicide Colletotrichum truncatum NRRL 13737

PubMed Central

Jackson, Mark A.; Bothast, Rodney J.

1990-01-01

We assessed the influence of various carbon concentrations and carbon-to-nitrogen (C:N) ratios on Colletotrichum truncatum NRRL 13737 conidium formation in submerged cultures grown in a basal salts medium containing various amounts of glucose and Casamino Acids. Under the nutritional conditions tested, the highest conidium concentrations were produced in media with carbon concentrations of 4.0 to 15.3 g/liter. High carbon concentrations (20.4 to 40.8 g/liter) inhibited sporulation and enhanced the formation of microsclerotiumlike hyphal masses. At all the carbon concentrations tested, a culture grown in a medium with a C:N ratio of 15:1 produced more conidia than cultures grown in media with C:N ratios of 40:1 or 5:1. While glucose exhaustion was often coincident with conidium formation, cultures containing residual glucose sporulated and those with high carbon concentrations (>25 g/liter) exhausted glucose without sporulation. Nitrogen source studies showed that the levels of C. truncatum NRRL 13737 conidiation were similar for all protein hydrolysates tested. Reduced conidiation occurred when amino acid and inorganic nitrogen sources were used. Of the nine carbon sources evaluated, acetate as the sole carbon source resulted in the lowest level of sporulation. Images PMID:16348348

Nitrogen Loading in Jamaica Bay, Long Island, New York: Predevelopment to 2005

USGS Publications Warehouse

Benotti, Mark J.; Abbene, Irene; Terracciano, Stephen A.

2007-01-01

Nitrogen loading to Jamaica Bay, a highly urbanized estuary on the southern shore of western Long Island, New York, has increased from an estimated rate of 35.6 kilograms per day (kg/d) under predevelopment conditions (pre-1900), chiefly as nitrate plus nitrite from ground-water inflow, to an estimated 15,800 kilograms per day as total nitrogen in 2005. The principal point sources are wastewater-treatment plants, combined sewer overflow/stormwater discharge during heavy precipitation, and subway dewatering, which account for 92 percent of the current (2005) nitrogen load. The principal nonpoint sources are landfill leachate, ground-water flow, and atmospheric deposition, which account for 8 percent of the current nitrogen load. The largest single source of nitrogen to Jamaica Bay is wastewater-treatment plants, which account for 89 percent of the nitrogen load. The current and historic contributions of nitrogen from seawater are unknown, although at present, the ocean likely serves as a sink for nitrogen from Jamaica Bay. Currently, concentrations of nitrogen in surface water are high throughout Jamaica Bay, but some areas with relatively little mixing have concentrations that are five times higher than areas that are well mixed.

Hydrogen and lipid production from starch wastewater by co-culture of anaerobic sludge and oleaginous microalgae with simultaneous COD, nitrogen and phosphorus removal.

PubMed

Ren, Hong-Yu; Liu, Bing-Feng; Kong, Fanying; Zhao, Lei; Ren, Nanqi

2015-11-15

Anaerobic sludge (AS) and microalgae were co-cultured to enhance the energy conversion and nutrients removal from starch wastewater. Mixed ratio, starch concentration and initial pH played critical roles on the hydrogen and lipid production of the co-culture system. The maximum hydrogen production of 1508.3 mL L(-1) and total lipid concentration of 0.36 g L(-1) were obtained under the optimized mixed ratio (algae:AS) of 30:1, starch concentration of 6 g L(-1) and initial pH of 8. The main soluble metabolites in dark fermentation were acetate and butyrate, most of which can be consumed in co-cultivation. When sweet potato starch wastewater was used as the substrate, the highest COD, TN and TP removal and energy conversion efficiencies reached 80.5%, 88.7%, 80.1% and 34.2%, which were 176%, 178%, 200% and 119% higher than that of the control group (dark fermentation), respectively. This research provided a novel approach and achieved efficient simultaneous energy recovery and nutrients removal from starch wastewater by the co-culture system. Copyright © 2015 Elsevier Ltd. All rights reserved.

Water-quality characteristics of five tributaries to the Chesapeake Bay at the Fall Line, Virginia, July 1988 through June 1993

USGS Publications Warehouse

Belval, D.L.; Campbell, J.P.; Phillips, S.W.; Bell, C.F.

1995-01-01

Development in the Chesapeake Bay region has adversely affected the water quality of the Bay. The general degradation in the Bay has resulted in the decline of commercial fishing industries and has reduced the area of aquatic vegetation that provides food and habitat for fish and shellfish. In order to assess the effectiveness of programs aimed at reducing the effects of excess nutrients and suspended solids on Chesapeake Bay, it is necessary to quantify the loads of these constituents into the Bay, and to evaluate the trends in water quality. This report presents the results of a study funded by the Virginia Department of Environmental Quality-Chesapeake Bay and Coastal Programs and the U.S. Geological Survey, to monitor and estimate loads of selected nutrients and suspended solids discharged to Chesapeake Bay from five major tributaries in Virginia. The water-quality data and load estimates provided in this report also will be used to calibrate computer models of Chesapeake Bay. Water-quality constituents were monitored in the James and Rappahannock Rivers over a 5-year period, and in the Pamunkey, Appomattox, and Mattaponi Rivers over a 4-year period. Water-quality samples were collected from July 1, 1988 through June 30, 1993, for the James and Rappahannock Rivers; from July 1, 1989 through June 30, 1993, for the Pamunkey and Appomattox Rivers; and from September 1, 1989 through June 30, 1993, for the Mattaponi River. Water-quality samples were collected on a scheduled basis and during stormflow to cover a range in discharge conditions. Monitored water-quality constituents, for which loads were estimated include total suspended solids (residue, total at 105 Celsius), dissolved nitrite-plus-nitrate nitrogen, dissolved ammonia nitrogen, total Kjeldahl nitrogen, total nitrogen, total phosphorus, dissolved orthophosphorus, total organic carbon, and dissolved silica. Organic nitrogen concentrations were calculated from measurements of ammonia and total Kjeldahl nitrogen, and organic nitrogen loads were estimated using these calculations. Other selected water-quality constituents were monitored for which loads were not calculated. Daily mean load estimates of each constituent were computed by use of a seven-parameter log-linear-regression model that uses variables of time, discharge, and seasonality. Concentration of total nitrogen ranged from less than 0.14 to 3.41 mg/L (milligrams per liter), with both extreme values occurring at the Rappahannock River. Concentration of total Kjeldahl nitrogen ranged from less than 0.1 mg/L in the James, Rappahannock, and Appomattox Rivers to 3.0 mg/L in the James River. Organic nitrogen was the predominant form of nitrogen at all stations except the Rappahannock River, where nitrite-plus-nitrate nitrogen was predominant, and organic nitrogen comprised the majority of the measured total Kjeldahl nitrogen at all stations, ranging from 0.01 mg/L in the Appomattox River to 2.86 mg/L in the James River. Concentration of dissolved ammonia nitrogen ranged from 0.01 mg/L in the Pamunkey River to 0.54 mg/L at the James River. Concentration of nitrite-plus-nitrate nitrogen ranged from 0.02 to 1.05 mg/L in the James River. Concentrations of total phosphorus ranged from less than 0.01 mg/L in the Rappahannock and the Mattaponi Rivers to 1.4 mg/L in the James River. Dissolved orthophosphorus ranged from less than 0.01 mg/L in all five rivers to 0.51 mg/L in the James River. Total suspended solids ranged from a concentration of less than 1 mg/L in all five rivers to 844 mg/L in the Rappahannock River. Total organic carbon ranged from 1.1 mg/L in the Appomattox River to 110 mg/L in the Rappahannock River. Dissolved silica ranged from 2.4 mg/L in the James River to 18 mg/L in the Appomattox River. The James and Rappahannock Rivers had high median concentrations and large ranges in concentrations for most constituents, probably because of a greater number of point and nonpoint sources of nutrients and suspend

Empirical regression models for estimating nitrogen removal in a stormwater wetland during dry and wet days.

PubMed

Guerra, Heidi B; Park, Kisoo; Kim, Youngchul

2013-01-01

Due to the highly variable hydrologic quantity and quality of stormwater runoff, which requires more complex models for proper prediction of treatment, a relatively few and site-specific models for stormwater wetlands have been developed. In this study, regression models based on extensive operational data and wastewater wetlands were adapted to a stormwater wetland receiving both base flow and storm flow from an agricultural area. The models were calibrated in Excel Solver using 15 sets of operational data gathered from random sampling during dry days. The calibrated models were then applied to 20 sets of event mean concentration data from composite sampling during 20 independent rainfall events. For dry days, the models estimated effluent concentrations of nitrogen species that were close to the measured values. However, overestimations during wet days were made for NH(3)-N and total Kjeldahl nitrogen, which resulted from higher hydraulic loading rates and influent nitrogen concentrations during storm flows. The results showed that biological nitrification and denitrification was the major nitrogen removal mechanism during dry days. Meanwhile, during wet days, the prevailing aerobic conditions decreased the denitrification capacity of the wetland, and sedimentation of particulate organic nitrogen and particle-associated forms of nitrogen was increased.

Relationships between Concentrations of Phytoplankton Chlorophyll a and Total Nitrogen in Ten U.S. Estuaries

EPA Science Inventory

This presentation focuses on the summertime response of phytoplankton chlorophyll to nitrogen concentrations in the upper water columns of ten U.S. estuaries. Using publicly available data from monitoring programs, regression relationships have been developed between summer surfa...

Biofiltration of air contaminated by styrene vapors on inorganic filtering media: an experimental study.

PubMed

St-Pierre, Marie-Claude Dion; Avalos Ramirez, Antonio; Heitz, Michèle

2009-05-01

This paper presents a study on the biofiltration of styrene by using two inorganic filtering materials. The effects of styrene inlet load and nitrogen concentration present in the nutrient solution on biofilter performance were studied. The styrene inlet concentration was varied from 65 to 1115 parts per million by volume (ppmv), whereas the contaminated airflow rate was fixed at 1 m3/hr. The nitrogen concentration in nutrient solution was varied from 1 to 4 gN/L. The maximum elimination capacity obtained was 105 g/m3-hr, which corresponded to a removal efficiency of 80% for a styrene inlet load of 130 g/m3-hr. This study shows that the nitrogen content in the nutrient solution affects the removal rate of styrene, with an optimal nitrogen concentration of 3 gN/L. The performance comparison between two different inorganic bed types was undertaken and a comparative study on biofiltration of two aromatic compounds, styrene and toluene, is also presented.

Seasonal changes in amino acids, protein and total nitrogen in needles of fertilized Scots pine trees.

PubMed

Näsholm, T; Ericsson, A

1990-09-01

Seasonal changes in amino acids, protein and total nitrogen in needles of 30-year-old, fertilized Scots pine (Pinus sylvestris L.) trees growing in Northern Sweden were investigated over two years in field experiments. The studied plots had been fertilized annually for 17 years with (i) a high level of N, (ii) a medium level of N, or (iii) a medium level of N, P and K. Trees growing on unfertilized plots served as controls. In control trees, glutamine, glutamic acid, gamma-aminobutyric acid, aspartic acid and proline represented 50-70% of the total free amino acids determined. Arginine was present only in low concentrations in control trees throughout the year, but it was usually the most abundant amino acid in fertilized trees. Glutamine concentrations were high during the spring and summer in both years of study, whereas proline concentrations were high in the spring but otherwise low throughout the year. In the first year of study, glutamic acid concentrations were high during the spring and summer, whereas gamma-aminobutyric acid was present in high concentrations during the winter months. This pattern was less pronounced in the second year of investigation. The concentrations of most amino acids, except glutamic acid, increased in response to fertilization. Nitrogen fertilization increased the foliar concentration of arginine from < 1 micromol g(dw) (-1) in control trees to a maximum of 110 micromol g(dw) (-1). Trees fertilized with nitrogen, phosphorus and potassium had significantly lower arginine concentrations than trees fertilized with the same amount of nitrogen only. Protein concentrations were similar in all fertilized trees but higher than those in control trees. For all treatments, protein concentrations were high in winter and at a minimum in early spring. In summer, the protein concentration remained almost constant except for a temporary decrease which coincided with the expansion of new shoots. Apart from arginine, the amino acid composition of proteins was similar in all treatments.

INCA Modelling of the Lee System: strategies for the reduction of nitrogen loads

NASA Astrophysics Data System (ADS)

Flynn, N. J.; Paddison, T.; Whitehead, P. G.

The Integrated Nitrogen Catchment model (INCA) was applied successfully to simulate nitrogen concentrations in the River Lee, a northern tributary of the River Thames for 1995-1999. Leaching from urban and agricultural areas was found to control nitrogen dynamics in reaches unaffected by effluent discharges and abstractions; the occurrence of minimal flows resulted in an upward trend in nitrate concentration. Sewage treatment works (STW) discharging into the River Lee raised nitrate concentrations substantially, a problem which was compounded by abstractions in the Lower Lee. The average concentration of nitrate (NO3) for the simulation period 1995-96 was 7.87 mg N l-1. Ammonium (NH4) concentrations were simulated less successfully. However, concentrations of ammonium rarely rose to levels which would be of environmental concern. Scenarios were run through INCA to assess strategies for the reduction of nitrate concentrations in the catchment. The conversion of arable land to ungrazed vegetation or to woodland would reduce nitrate concentrations substantially, whilst inclusion of riparian buffer strips would be unsuccessful in reducing nitrate loading. A 50% reduction in nitrate loading from Luton STW would result in a fall of up to 5 mg N l-1 in the reach directly affected (concentrations fell from maxima of 13 to 8 mg N l-1 , nearly a 40 % reduction), whilst a 20% reduction in abstractions would reduce maximum peaks in concentration in the lower Lee by up to 4 mg l-1 (from 17 to 13 mg N l-1, nearly a 25 % reduction),.

Contrasted nitrogen utilization in annual C 3 grass and legume crops: Physiological explorations and ecological considerations

NASA Astrophysics Data System (ADS)

Del Pozo, Alejandro; Garnier, Eric; Aronson, James

2000-01-01

Although it is well known that legumes have unusually high levels of nitrogen in both reproductive and vegetative organs, the physiological implications of this pattern have been poorly assessed. We conducted a literature survey and used data from two (unpublished) experiments on annual legumes and C 3 grasses in order to test whether these high nitrogen concentrations in legumes are correlated to high rates of carbon gain. Three different temporal/spatial scales were considered: full growing season/stand, days to month/whole plant and seconds/leaf. At the stand level, and for plants grown under both extratropical and tropical settings, biomass per unit organic-nitrogen was lower in legume than in grass crops. At a shorter time scale, the relative growth rate per unit plant nitrogen (`nitrogen productivity') was lower in faba bean ( Vicia faba var. minor cv. Tina) than in wheat ( Triticum aestivum cv. Alexandria), and this was confirmed in a comparison of two wild, circum-Mediterranean annuals - Medicago minima, a legume, and Bromus madritensis, a grass. Finally, at the leaf level, a synthesis of published data comparing soybean ( Glycine max) and rice ( Oryza sativa) on the one hand, and our own data on faba bean and wheat on the other hand, demonstrates that the photosynthetic rate per unit leaf nitrogen (the photosynthetic nitrogen use efficiency) is consistently lower in legumes than in grasses. These results demonstrate that, regardless of the scale considered and although the organic-nitrogen concentration in vegetative organs of legumes is higher than in grasses, this does not lead to higher rates of carbon gain in the former. Various physiological factors affecting the efficiency of nitrogen utilization at the three time scales considered are discussed. The suggestion is made that the ecological significance of the high nitrogen concentration in legumes may be related to a high nitrogen demand for high quality seed production at a time when nitrogen fixation is shut off rather than to a high production potential.

Somatic embryogenesis of carrot in hormone-free medium: external pH control over morphogenesis

NASA Technical Reports Server (NTRS)

Smith, D. L.; Krikorian, A. D.

1990-01-01

Cultures of preglobular stage proembryos (PGSPs) were initiated from mechanically wounded mature zygotic embryos of carrot, Daucus carota, on a hormone-free, semisolid medium. These PGSPs have been maintained and multiplied for extended periods without their progression into later embryo stages on the same hormone-free medium containing 1 mM NH4+ as the sole nitrogen source. Sustained maintenance of cultures comprised exclusively of PGSPs was dependent on medium pH throughout the culture period. Best growth and multiplication of PGSP cultures occurred when the pH of unbuffered, hormone-free medium fell from 4.5 to 4 over a 2-week period or when buffered medium was titrated to pH 4. If the hormone-free medium was buffered to sustain a pH at or above 4.5, PGSPs developed into later embryo stages. Maintenance with continuous multiplication of PGSPs occurred equally well on medium containing NH4+ or NH4+ and NO3-, but growth was poor with NO3- alone. Additional observations on the effects of medium components such as various nitrogen sources and levels, sucrose concentration, semisolid supports, type of buffer, borate concentration, activated charcoal, and initial pH that permit optimum maintenance of the PGSPs or foster their continued developmental progression into mature embryos and plantlets are reported. The influence of the pH of the hormone-free medium as a determinant in maintaining cultures as PGSPs or allowing their continued embryonic development are unequivocally demonstrated by gross morphology, scanning electron microscopy, and histological preparations.

Occurrence of anthropogenic organic compounds and nutrients in source and finished water in the Sioux Falls area, South Dakota, 2009-10

USGS Publications Warehouse

Hoogestraat, Galen K.

2012-01-01

Anthropogenic organic compounds (AOCs) in drinking-water sources commonly are derived from municipal, agricultural, and industrial wastewater sources, and are a concern for water-supply managers. A cooperative study between the city of Sioux Falls, S. Dak., and the U.S. Geological Survey was initiated in 2009 to (1) characterize the occurrence of anthropogenic organic compounds in the source waters (groundwater and surface water) to water supplies in the Sioux Falls area, (2) determine if the compounds detected in the source waters also are present in the finished water, and (3) identify probable sources of nitrate in the Big Sioux River Basin and determine if sources change seasonally or under different hydrologic conditions. This report presents analytical results of water-quality samples collected from source waters and finished waters in the Sioux Falls area. The study approach included the collection of water samples from source and finished waters in the Sioux Falls area for the analyses of AOCs, nutrients, and nitrogen and oxygen isotopes in nitrate. Water-quality constituents monitored in this study were chosen to represent a variety of the contaminants known or suspected to occur within the Big Sioux River Basin, including pesticides, pharmaceuticals, sterols, household and industrial products, polycyclic aromatic hydrocarbons, antibiotics, and hormones. A total of 184 AOCs were monitored, of which 40 AOCs had relevant human-health benchmarks. During 11 sampling visits, 45 AOCs (24 percent) were detected in at least one sample of source or finished water, and 13 AOCs were detected in at least 20 percent of all samples. Concentrations of detected AOCs were all less than 1 microgram per liter, except for two AOCs in multiple samples from the Big Sioux River, and one AOC in finished-water samples. Concentrations of AOCs were less than 0.1 microgram per liter in more than 75 percent of the detections. Nutrient concentrations varied seasonally in source-water samples from surface water and groundwater. In the Big Sioux River, nitrite plus nitrate concentrations were typically less than 1 milligram per liter as nitrogen, and reached a maximum of 4.06 milligrams per liter as nitrogen following a June 2010 storm. Nitrite plus nitrate concentrations in groundwater ranged from less than 0.1 to 0.701 milligram per liter as nitrogen. Eight of the AOCs detected have a human-health benchmark that could be used to evaluate the concentrations in a human-health context. Four AOCs had maximum concentrations within an order of magnitude of the benchmark, indicating that additional monitoring of the compound may be warranted. Three herbicides (atrazine, metolachlor, and prometon) and one degradate (deethylatrazine) were detected in finished-water samples as frequently as in source-water samples. The concentrations of herbicides in source water varied by an order of magnitude from the period of peak use (early summer) to the winter months. Groundwater and finished-water concentrations of atrazine were similar for the six sampling dates when groundwater was the only source water used. Upstream wastewater discharges contributed a fairly small percentage of the flow to the Big Sioux River near Sioux Falls, but several AOCs associated with wastewater were frequently detected. The interpretation of all potential sources of nitrogen cannot be accomplished by use of nitrogen and oxygen isotopes in nitrate alone, but provides a qualitative indication that very little nitrate originates from excess fertilizer runoff, and most nitrate originates from municipal wastewater effluent, manure runoff (either from field application or feeding operations), or fertilizers mineralized by processes in the soil.

Performance and microbial features of the partial nitritation-anammox process treating fish canning wastewater with variable salt concentrations.

PubMed

Val Del Rio, Angeles; Pichel, Andres; Fernandez-Gonzalez, Nuria; Pedrouso, Alba; Fra-Vázquez, Andrea; Morales, Nicolas; Mendez, Ramon; Campos, Jose Luis; Mosquera-Corral, Anuska

2018-02-15

The partial nitritation-anammox (PN-AMX) process applied to wastewaters with high NaCl concentration was studied until now using simulated media, without considering the effect of organic matter concentration and the shift in microbial populations. This research work presents results on the application of this process to the treatment of saline industrial wastewater. Obtained results indicated that the PN-AMX process has the capability to recover its initial activity after a sudden/acute salt inhibition event (up to 16 g NaCl/L). With a progressive salt concentration increase for 150 days, the PN-AMX process was able to remove the 80% of the nitrogen at 7-9 g NaCl/L. The microbiological data indicated that NaCl and ammonia concentrations and temperature are important factors shaping PN-AMX communities. Thus, the NOB abundance (Nitrospira) decreases with the increase of the salt concentration, while heterotrophic denitrifiers are able to outcompete anammox after a peak of organic matter in the feeding. Copyright © 2017 Elsevier Ltd. All rights reserved.

Aqueous phase removal of nitrogen from nitrogen compounds

DOEpatents

Fassbender, Alex G.

1993-01-01

A method is disclosed for denitrification of compounds containing nitrogen present in aqueous waste streams. The method comprises the steps of (1) identifying the types of nitrogen compounds present in a waste stream, (2) determining the concentrations of nitrogen compounds, (3) balancing oxidized and reduced form of nitrogen by adding a reactant, and (4) heating the mixture to a predetermined reaction temperature from about 300.degree. C. to about 600.degree. C., thereby resulting in less harmful nitrogen and oxygen gas, hydroxides, alcohols, and hydrocarbons.

Watershed characteristics and water-quality trends and loads in 12 watersheds in Gwinnett County, Georgia

USGS Publications Warehouse

Joiner, John K.; Aulenbach, Brent T.; Landers, Mark N.

2014-01-01

The U.S. Geological Survey, in cooperation with Gwinnett County Department of Water Resources, established a Long-Term Trend Monitoring (LTTM) program in 1996. The LTTM program is a comprehensive, long-term, water-quantity and water-quality monitoring program designed to document and analyze the hydrologic and water-quality conditions of selected watersheds of Gwinnett County, Georgia. Water-quality monitoring initially began in six watersheds and was expanded to another six watersheds in 2001. As part of the LTTM program, streamflow, precipitation, water temperature, specific conductance, and turbidity were measured continuously at the 12 watershed monitoring stations for water years 2004–09. In addition, discrete water-quality samples were collected seasonally from May through October (summer) and November through April (winter), including one base-flow and three stormflow event composite samples, during the study period. Samples were analyzed for nutrients (nitrogen and phosphorus), total organic carbon, trace elements (total lead and total zinc), total dissolved solids, and total suspended sediment (total suspended solids and suspended-sediment concentrations). The sampling scheme was designed to identify variations in water quality both hydrologically and seasonally. The 12 watersheds were characterized for basin slope, population density, land use for 2009, and the percentage of impervious area from 2000 to 2009. Precipitation in water years 2004–09 was about 18 percent below average, and the county experienced exceptional drought conditions and below average runoff in water years 2007 and 2008. Watershed water yields, the percentage of precipitation that results in runoff, typically are lower in low precipitation years and are higher for watersheds with the highest percentages of impervious areas. A comparison of base-flow and stormflow water-quality samples indicates that turbidity and concentrations of total ammonia plus organic nitrogen, total nitrogen, total phosphorus, total organic carbon, total lead, total zinc, total suspended solids, and suspended-sediment concentrations increased with increasing discharge at all watersheds. Specific conductance, however, decreased during stormflow at all watersheds, and total dissolved solids concentrations decreased during stormflow at a few of the watersheds. Total suspended solids and suspended-sediment concentrations typically were two orders of magnitude higher in stormflow samples, turbidities were about 1.5 orders of magnitude higher, total phosphorus and total zinc were about one order of magnitude higher, and total ammonia plus organic nitrogen, total nitrogen, total organic carbon, and total lead were about twofold higher than in base-flow samples. Seasonal patterns and long-term trends in flow-adjusted water-quality concentrations were identified for five representative constituents—total nitrogen, total phosphorus, total zinc, total dissolved solids, and total suspended solids. Seasonal patterns for all five constituents were fairly similar, with higher concentrations in the summer and lower concentrations in the winter. Significant linear long-term trends in stormflow composite concentrations were identified for 36 of the 60 constituent-watershed combinations (5 constituents multiplied by 12 watersheds) for the period of record through water year 2011. Significant trends typically were decreasing for total nitrogen, total phosphorus, total suspended solids, and total zinc and increasing for total dissolved solids. Total dissolved solids and total suspended solids trends had the largest magnitude changes per year. Stream water loads were estimated for 10 water-quality constituents. These estimates represent the cumulative effects of watershed characteristics, hydrologic processes, biogeochemical processes, climatic variability, and human influences on watershed water quality. Yields, in load per unit area, were used to compare loads from watersheds with different sizes. A load estimation approach developed for the Gwinnett County LTTM program that incorporates storm-event composited samples was used with some minor modifications. This approach employs the commonly used regression-model method. Concentrations were modeled as a function of discharge, time, season, and turbidity to improve model predictions and reduce errors in load estimates. Total suspended solids annual loads have been identified in Gwinnett County’s Watershed Protection Plan for target performance criterion. The amount of annual runoff is the primary factor in determining the amount of annual constituent loads. Below average runoff during water years 2004–09, especially during water years 2006–08, resulted in corresponding below average loads. Variations in constituent yields between watersheds appeared to be related to various watershed characteristics. Suspended sediment (total suspended solids and suspended-sediment concentrations) along with constituents transported predominately in solid phase (total phosphorus, total organic carbon, total lead, and total zinc) and total dissolved solids typically had higher yields from watersheds that had high percentages of impervious areas or high basin slope. High total nitrogen yields were also associated with watersheds with high percentages of impervious areas. Low total nitrogen, total suspended solids, total lead, and total zinc yields appear to be associated with watersheds that have a low percentage of high-density development. Total suspended solids yields were lower in drought years, water years 2007–08, from the combined effects of less runoff and the result of fewer, lower magnitude storms, which likely resulted in less surface erosion and lower stream sediment transport.

Concentrations and possible sources of nitrate in water from the Silurian-Devonian aquifer, Cedar Falls, Iowa

USGS Publications Warehouse

Schaap, Bryan D.

1999-01-01

Nitrogen fertilizer sales in Iowa have been higher in recent years than during the mid- 1970’s. This suggests that nitrate concentrations in water from well 9 may persist at present levels or could increase in future years if fertilizer use increases and if higher nitrate concentrations are directly related to higher nitrogen fertilizer use.

Analysis of hyperspectral data for estimation of temperate forest canopy nitrogen concentration: comparison between an airborne (AVIRIS) and a spaceborne (Hyperion) sensor

Treesearch

Marie-Louise Smith; Mary E. Martin; Lucie Plourde; Scott V. Ollinger

2003-01-01

Field studies among diverse biomes demonstrate that mass-based nitrogen concentration at leaf and canopy scales is strongly related to carbon uptake and cycling. Combined field and airborne imaging spectrometry studies demonstrate the capacity for accurate empirical estimation of forest canopy N concentration and other biochemical constituents at scales from forest...

Physiological responses of wild type and putrescine-overproducing transgenic cells of poplar to variations in the form and concentration of nitrogen in the medium

Treesearch

Rakesh Minocha; Jae Soon Lee; Stephanie Long; Pratiksha Bhatnagar; Subhash C. Minocha

2004-01-01

We determined: (a) the physiological consequences of overproduction of putrescine in transgenic poplar (Populus nigra x mnrimoviczir) cells expressing an omithine decarboxylase transgene; and (b) effects of variation in nitrogen (N) concentration of the medium on cellular polyamine concentration in transgenic and non-transgenic cells. Cells grown in...

Climate-mediated nitrogen and carbon dynamics in a tropical watershed

NASA Astrophysics Data System (ADS)

Ballantyne, A. P.; Baker, P. A.; Fritz, S. C.; Poulter, B.

2011-06-01

Climate variability affects the capacity of the biosphere to assimilate and store important elements, such as nitrogen and carbon. Here we present biogeochemical evidence from the sediments of tropical Lake Titicaca indicating that large hydrologic changes in response to global glacial cycles during the Quaternary were accompanied by major shifts in ecosystem state. During prolonged glacial intervals, lake level was high and the lake was in a stable nitrogen-limited state. In contrast, during warm dry interglacials lake level fell and rates of nitrogen concentrations increased by a factor of 4-12, resulting in a fivefold to 24-fold increase in organic carbon concentrations in the sediments due to increased primary productivity. Observed periods of increased primary productivity were also associated with an apparent increase in denitrification. However, the net accumulation of nitrogen during interglacial intervals indicates that increased nitrogen supply exceeded nitrogen losses due to denitrification, thereby causing increases in primary productivity. Although primary productivity in tropical ecosystems, especially freshwater ecosystems, tends to be nitrogen limited, our results indicate that climate variability may lead to changes in nitrogen availability and thus changes in primary productivity. Therefore some tropical ecosystems may shift between a stable state of nitrogen limitation and a stable state of nitrogen saturation in response to varying climatic conditions.

The effect of carbohydrate accumulation and nitrogen deficiency on feedback regulation of photosynthesis in beech (Fagus sylvatica) under elevated CO2 concentration

NASA Astrophysics Data System (ADS)

Klem, K.; Urban, O.; Holub, P.; Rajsnerova, P.

2012-04-01

One of the main manifestations of global change is an increase in atmospheric CO2 concentration. Elevated concentration of CO2 has stimulating effect on plant photosynthesis and consequently also on the productivity. Long-term studies, however, show that this effect is progressively reduced due to feedback regulation of photosynthesis. The main causes of this phenomenon are considered as two factors: i) increased biomass production consumes a larger amount of nitrogen from the soil and this leads to progressive nitrogen limitation of photosynthesis, particularly at the level of the enzyme Rubisco, ii) the sink capacity is genetically limited and elevated CO2 concentration leads to increased accumulation of carbohydtrates (mainly sucrose, which is the main transport form of assimilates) in leaves. Increased concentrations of carbohydrates leads to a feedback regulation of photosynthesis by both, long-term feedback regulation of synthesis of the enzyme Rubisco, and also due to reduced capacity to produce ATP in the chloroplasts. However, mechanisms for interactive effects of nitrogen and accumulation of non-structural carbohydrates are still not well understood. Using 3-year-old Fagus sylvatica seedlings we have explored the interactive effects of nitrogen nutrition and sink capacity manipulation (sucrose feeding) on the dynamics of accumulation of non-structural carbohydrates and changes in photosynthetic parameters under ambient (385 μmol (CO2) mol-1) and elevated (700 μmol(CO2) mol-1) CO2 concentration. Sink manipulation by sucrose feeding led to a continuous increase of non-structural carbohydrates in leaves, which was higher in nitrogen fertilized seedlings. The accumulation of non-structural carbohydrates was also slightly stimulated by elevated CO2 concentration. Exponential decay (p <0.01) was observed in CO2 assimilation rate and stomatal conductance when the content of non-structural carbohydrates increased. However, this relationship was modified by the nitrogen content. Accumulation of non-structural carbohydrates had relatively smaller effect on actual quantum yield of photosystem II. Both, CO2 assimilation rate and the actual quantum yield of photosystem II decreased more rapidly during sink manipulation in elevated concentrations of CO2 than in ambient. Application of chlorophyll fluorescence imaging enabled us to evaluate changes in spatial distribution of feedback regulation of photosynthesis on the leaf-level. We can conclude that the accumulation of non-structural carbohydrates down-regulates photosynthesis mainly through the stomatal conductance, and this effect is further modified by nitrogen content.

Tracking the Fate of Explosive-Trinitrotriazine (RDX) in Coastal Marine Ecosystems Using Stable Isotopic Tracer

NASA Astrophysics Data System (ADS)

Ariyarathna, T. S.; Ballentine, M.; Vlahos, P.; Smith, R. W.; Bohlke, J. K.; Tobias, C. R.; Fallis, S.; Groshens, T.; Cooper, C.

2017-12-01

It has been estimated that there are hundreds of explosive-contaminated sites all over the world and managing these contaminated sites is an international challenge. As coastal zones and estuaries are commonly impacted zones, it is vital to understand the fate and transport of munition compounds in these environments. The demand for data on sorption, biodegradation and mineralization of trinitrotriazine (RDX) in coastal ecosystems is the impetus for this study using stable nitrogen isotopes to track its metabolic pathways. Mesocosm experiments representing subtidal vegetated, subtidal unvegetated and intertidal marsh ecocosms were conducted. Steady state concentrations of RDX were maintained in the systems throughout two-week time duration of experiments. Sediment, pore-water and overlying water samples were analyzed for RDX and degradation products. Isotope analysis of the bulk sediments revealed an initial rising inventory of 15N followed by a decay illustrating the role of sediments on sorption and degradation of RDX in anaerobic sediments respectively. Both pore-water and overlying water samples were analyzed for 15N inventories of different inorganic nitrogen pools including ammonium, nitrate, nitrite, nitrous oxide and nitrogen gases. RDX is mineralized to nitrogen gas through a series of intermediates leaving nitrous oxide as the prominent metabolite of RDX. Significant differences in RDX metabolism were observed in the three different ecosystems based on sediment characteristics and redox conditions in the systems. Fine grained organic carbon rich sediments show notably higher mineralization rates of RDX in terms of production of its metabolites. Quantification of degradation and transformation rates leads to mass balances of RDX in the systems. Further analysis of results provides insights for mineralization pathways of RDX into both organic and inorganic nitrogen pools entering the marine nitrogen cycle.

Inorganic nitrogen availability after severe stand-replacing fire in the Greater Yellowstone ecosystem

PubMed Central

Turner, Monica G.; Smithwick, Erica A. H.; Metzger, Kristine L.; Tinker, Daniel B.; Romme, William H.

2007-01-01

Understanding ecosystem processes as they relate to wildfire and vegetation dynamics is of growing importance as fire frequency and extent increase throughout the western United States. However, the effects of severe, stand-replacing wildfires are poorly understood. We studied inorganic nitrogen pools and mineralization rates after stand-replacing wildfires in the Greater Yellowstone Ecosystem, Wyoming. After fires that burned in summer 2000, soil ammonium concentration peaked in 2001 (33 mg NH4-N· kgsoil−1); soil nitrate increased subsequently (2.7 mg NO3-N·kgsoil−1 in 2003) but was still low. However, annual net ammonification rates were largely negative from 2001 to 2004, indicating ammonium depletion. Thus, although net nitrification rates were positive, annual net nitrogen mineralization (net ammonification plus net nitrification) remained low. Aboveground net primary production (ANPP) increased from 0.25 to 1.6 Mg·ha−1·yr−1 from 2001 to 2004, but variation in ANPP among stands was not related to net nitrogen mineralization rates. Across a broader temporal gradient (stand age zero to >250 yr), negative rates of net annual ammonification were especially pronounced in the first postfire year. Laboratory incubations using 15N isotope pool dilution revealed that gross production of ammonium was reduced and ammonium consumption greatly exceeded gross production during the initial postfire years. Our results suggest a microbial nitrogen sink for several years after severe, stand-replacing fire, confirming earlier hypotheses about postdisturbance succession and nutrient cycling in cold, fire-dominated coniferous forests. Postfire forests in Yellowstone seem to be highly conservative for nitrogen, and microbial immobilization of ammonium plays a key role during early succession. PMID:17360349

Nitrate assimilation is inhibited by elevated CO2 in field-grown wheat

NASA Astrophysics Data System (ADS)

J. Bloom, Arnold; Burger, Martin; A. Kimball, Bruce; J. Pinter, Paul, Jr.

2014-06-01

Total protein and nitrogen concentrations in plants generally decline under elevated CO2 atmospheres. Explanations for this decline include that plants under elevated CO2 grow larger, diluting the protein within their tissues; that carbohydrates accumulate within leaves, downregulating the amount of the most prevalent protein Rubisco; that carbon enrichment of the rhizosphere leads to progressively greater limitations of the nitrogen available to plants; and that elevated CO2 directly inhibits plant nitrogen metabolism, especially the assimilation of nitrate into proteins in leaves of C3 plants. Recently, several meta-analyses have indicated that CO2 inhibition of nitrate assimilation is the explanation most consistent with observations. Here, we present the first direct field test of this explanation. We analysed wheat (Triticum aestivum L.) grown under elevated and ambient CO2 concentrations in the free-air CO2 enrichment experiment at Maricopa, Arizona. In leaf tissue, the ratio of nitrate to total nitrogen concentration and the stable isotope ratios of organic nitrogen and free nitrate showed that nitrate assimilation was slower under elevated than ambient CO2. These findings imply that food quality will suffer under the CO2 levels anticipated during this century unless more sophisticated approaches to nitrogen fertilization are employed.

Effect of coastal eutrophication on growth and physiology of Spartina alterniflora Loisel

NASA Astrophysics Data System (ADS)

Zhang, Yu; Cui, Baoshan; Xie, Tian; Wang, Qing; Yan, Jiaguo

2018-02-01

Coastal eutrophication has become a driver of coastal wetlands loss. Eutrophication caused by the increase of nitrogen content was one of the most main reasons. We analyzed that exogenous ammonium nitrogen (EAN) of different concentration influenced on the growth and physiology of Spartina alterniflora Loisel (S. alterniflora) through simulated conditions. The results showed that growth of the root system largely depended on the environment conditions around S. alterniflora. Higher nitrogen concentration promoted aboveground biomass and increased plant height. On the other hand, as the increase of growth period, higher nitrogen concentration could inhibit the elongation growth of root and reduce the underground biomass. We showed that activity of POD, SOD and MDA content changed in an upward trend along with the increased nitrogen level. There was a significant positive correlation between H+ flux and NO3- flux (r = 0.601, P < 0.01), and a significant negative correlation between H+ flux and NH4+ flux (r = -0.713, P < 0.01) within 1.5 mm from the root tip of S. alterniflora. Efflux and influx of ions were associated with changes of nitrogen levels. This research will provide data supporting for coastal wetland restoration of biodiversity reduction caused by coastal eutrophication.

Least-cost input mixtures of water and nitrogen for photosynthesis.

PubMed

Wright, Ian J; Reich, Peter B; Westoby, Mark

2003-01-01

In microeconomics, a standard framework is used for determining the optimal input mix for a two-input production process. Here we adapt this framework for understanding the way plants use water and nitrogen (N) in photosynthesis. The least-cost input mixture for generating a given output depends on the relative cost of procuring and using nitrogen versus water. This way of considering the issue integrates concepts such as water-use efficiency and photosynthetic nitrogen-use efficiency into the more inclusive objective of optimizing the input mix for a given situation. We explore the implications of deploying alternative combinations of leaf nitrogen concentration and stomatal conductance to water, focusing on comparing hypothetical species occurring in low- versus high-humidity habitats. We then present data from sites in both the United States and Australia and show that low-rainfall species operate with substantially higher leaf N concentration per unit leaf area. The extra protein reflected in higher leaf N concentration is associated with a greater drawdown of internal CO2, such that low-rainfall species achieve higher photosynthetic rates at a given stomatal conductance. This restraint of transpirational water use apparently counterbalances the multiple costs of deploying high-nitrogen leaves.

[Effects of simulated nitrogen deposition on organic matter leaching in forest soil].

PubMed

Duan, Lei; ma, Xiao-Xiao; Yu, De-Xiang; Tan, Bing-Quan

2013-06-01

The impact of nitrogen deposition on the dynamics of carbon pool in forest soil was studied through a field experiment at Tieshanping, Chongqing in Southwest China. The changes of dissolved organic matter (DOM) concentration in soil water in different soil layers were monitored for five years after addition of ammonium nitrate (NH4NO3) or sodium nitrate (NaNO3) at the same dose as the current nitrogen deposition to the forest floor. The results indicated that the concentration and flux of dissolved organic carbon (DOC) were increased in the first two years and then decreased by fertilizing. Fertilizing also reduced the DOC/DON (dissolved organic nitrogen) ratio of soil water in the litter layer and the DOC concentration of soil water in the upper mineral layer, but had no significant effect on DOC flux in the lower soil layer. Although there was generally no effect of increasing nitrogen deposition on the forest carbon pool during the experimental period, the shift from C-rich to N-rich DOM might occur. In addition, the species of nitrogen deposition, i. e., NH4(+) and NO3(-), did not show difference in their effect on soil DOM with the same equivalence.

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

USGS Publications Warehouse

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

2014-01-01

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

40 CFR 60.55a - Standard for nitrogen oxides.

Code of Federal Regulations, 2013 CFR

2013-07-01

... 40 Protection of Environment 7 2013-07-01 2013-07-01 false Standard for nitrogen oxides. 60.55a... § 60.55a Standard for nitrogen oxides. On and after the date on which the initial compliance test is... gases that contain nitrogen oxides in excess of 180 parts per million by volume, corrected to 7 percent...

40 CFR 60.55a - Standard for nitrogen oxides.

Code of Federal Regulations, 2011 CFR

2011-07-01

... 40 Protection of Environment 6 2011-07-01 2011-07-01 false Standard for nitrogen oxides. 60.55a... § 60.55a Standard for nitrogen oxides. On and after the date on which the initial compliance test is... gases that contain nitrogen oxides in excess of 180 parts per million by volume, corrected to 7 percent...

40 CFR 60.55a - Standard for nitrogen oxides.

Code of Federal Regulations, 2012 CFR

2012-07-01

... 40 Protection of Environment 7 2012-07-01 2012-07-01 false Standard for nitrogen oxides. 60.55a... § 60.55a Standard for nitrogen oxides. On and after the date on which the initial compliance test is... gases that contain nitrogen oxides in excess of 180 parts per million by volume, corrected to 7 percent...

40 CFR 60.55a - Standard for nitrogen oxides.

Code of Federal Regulations, 2014 CFR

2014-07-01

... 40 Protection of Environment 7 2014-07-01 2014-07-01 false Standard for nitrogen oxides. 60.55a... § 60.55a Standard for nitrogen oxides. On and after the date on which the initial compliance test is... gases that contain nitrogen oxides in excess of 180 parts per million by volume, corrected to 7 percent...

Influence of abscisic acid on growth, biomass and lipid yield of Scenedesmus quadricauda under nitrogen starved condition.

PubMed

Sulochana, Sujitha Balakrishnan; Arumugam, Muthu

2016-08-01

Scenedesmus quadricauda, accumulated more lipid but with a drastic reduction in biomass yield during nitrogen starvation. Abscisic acid (ABA) being a stress responsible hormone, its effect on growth and biomass with sustainable lipid yield during nitrogen depletion was studied. The result revealed that the ABA level shoots up at 24h (27.21pmol/L) during the onset of nitrogen starvation followed by a sharp decline. The external supplemented ABA showed a positive effect on growth pattern (38×10(6)cells/ml) at a lower concentration. The dry biomass yield is also increasing up to 2.1 fold compared to nitrogen deficient S. quadricauda. The lipid content sustains in 1 and 2μM concentration of ABA under nitrogen-deficient condition. The fatty acid composition of ABA treated S. quadricauda cultures with respect to nitrogen-starved cells showed 11.17% increment in saturated fatty acid content, the desired lipid composition for biofuel application. Copyright © 2016 Elsevier Ltd. All rights reserved.

The mechanism of improved pullulan production by nitrogen limitation in batch culture of Aureobasidium pullulans.

PubMed

Wang, Dahui; Chen, Feifei; Wei, Gongyuan; Jiang, Min; Dong, Mingsheng

2015-08-20

Batch culture of Aureobasidium pullulans CCTCC M 2012259 for pullulan production at different concentrations of ammonium sulfate and yeast extract was investigated. Increased pullulan production was obtained under nitrogen-limiting conditions, as compared to that without nitrogen limitation. The mechanism of nitrogen limitation favoring to pullulan overproduction was revealed by determining the activity as well as gene expression of key enzymes, and energy supply for pullulan biosynthesis. Results indicated that nitrogen limitation increased the activities of α-phosphoglucose mutase and glucosyltransferase, up-regulated the transcriptional levels of pgm1 and fks genes, and supplied more ATP intracellularly, which were propitious to further pullulan biosynthesis. The economic analysis of batch pullulan production indicated that nitrogen limitation could reduce more than one third of the cost of raw materials when glucose was supplemented to a total concentration of 70 g/L. This study also helps to understand the mechanism of other polysaccharide overproduction by nitrogen limitation. Copyright © 2015 Elsevier Ltd. All rights reserved.

Volcanism and the atmosphere: the potential role of the atmosphere in unlocking the reactivity of volcanic emissions.

PubMed

Mather, Tamsin A

2008-12-28

Recent measurements of reactive trace gas species in volcanic plumes have offered intriguing hints at the chemistry occurring in the hot environment at volcanic vents. This has led to the recognition that volcanic vents should be regarded not only as passive sources of volcanic gases to the atmosphere, but also as 'reaction vessels' that unlock otherwise inert volcanic and atmospheric gas species. The atypical conditions created by the mixing of ambient atmosphere with the hot gases emitted from magma give rise to elevated concentrations of otherwise unexpected chemical compounds. Rapid cooling of this mixture allows these species to persist into the environment, with important consequences for gas plume chemistry and impacts. This paper discusses some examples of the implications of these high-temperature interactions in terms of nitrogen, halogen and sulphur chemistry, and their consequences in terms of the global fixed nitrogen budget, volcanically induced ozone destruction and particle fluxes to the atmosphere. Volcanically initiated atmospheric chemistry was likely to have been particularly important before biological (and latterly anthropogenic) processes started to dominate many geochemical cycles, with important consequences in terms of the evolution of the nitrogen cycle and the role of particles in modulating the Earth's climate.

Ultrafine particles and nitrogen oxides generated by gas and electric cooking

PubMed Central

Dennekamp, M; Howarth, S; Dick, C; Cherrie, J; Donaldson, K; Seaton, A

2001-01-01

OBJECTIVES—To measure the concentrations of particles less than 100 nm diameter and of oxides of nitrogen generated by cooking with gas and electricity, to comment on possible hazards to health in poorly ventilated kitchens.
METHODS—Experiments with gas and electric rings, grills, and ovens were used to compare different cooking procedures. Nitrogen oxides (NOx) were measured by a chemiluminescent ML9841A NOx analyser. A TSI 3934 scanning mobility particle sizer was used to measure average number concentration and size distribution of aerosols in the size range 10-500 nm.
RESULTS—High concentrations of particles are generated by gas combustion, by frying, and by cooking of fatty foods. Electric rings and grills may also generate particles from their surfaces. In experiments where gas burning was the most important source of particles, most particles were in the size range 15-40 nm. When bacon was fried on the gas or electric rings the particles were of larger diameter, in the size range 50-100 nm. The smaller particles generated during experiments grew in size with time because of coagulation. Substantial concentrations of NOX were generated during cooking on gas; four rings for 15 minutes produced 5 minute peaks of about 1000 ppb nitrogen dioxide and about 2000 ppb nitric oxide.
CONCLUSIONS—Cooking in a poorly ventilated kitchen may give rise to potentially toxic concentrations of numbers of particles. Very high concentrations of oxides of nitrogen may also be generated by gas cooking, and with no extraction and poor ventilation, may reach concentrations at which adverse health effects may be expected. Although respiratory effects of exposure to NOx might be anticipated, recent epidemiology suggests that cardiac effects cannot be excluded, and further investigation of this is desirable.


Keywords: cooking fuels; nitrogen oxides; ultrafine particles PMID:11452045

Nutrient Mass Balance for the Mobile River Basin in Alabama, Georgia, and Mississippi

NASA Astrophysics Data System (ADS)

Harned, D. A.; Harvill, J. S.; McMahon, G.

2001-12-01

The source and fate of nutrients in the Mobile River drainage basin are important water-quality concerns in Alabama, Georgia, and Mississippi. Land cover in the basin is 74 percent forested, 16 percent agricultural, 2.5 percent developed, and 4 percent wetland. A nutrient mass balance calculated for 18 watersheds in the Mobile River Basin indicates that agricultural non-point nitrogen and phosphorus sources and urban non-point nitrogen sources are the most important factors associated with nutrients in the streams. Nitrogen and phosphorus inputs from atmospheric deposition, crop fertilizer, biological nitrogen fixation, animal waste, and point sources were estimated for each of the 18 drainage basins. Total basin nitrogen inputs ranged from 27 to 93 percent from atmospheric deposition (56 percent mean), 4 to 45 percent from crop fertilizer (25 percent mean), <0.01 to 31 percent from biological nitrogen fixation (8 percent mean), 2 to 14 percent from animal waste (8 percent mean), and 0.2 to 11 percent from point sources (3 percent mean). Total basin phosphorus inputs ranged from 10 to 39 percent from atmospheric deposition (26 percent mean), 7 to 51 percent from crop fertilizer (28 percent mean), 20 to 64 percent from animal waste (41 percent mean), and 0.2 to 11 percent from point sources (3 percent mean). Nutrient outputs for the watersheds were estimated by calculating instream loads and estimating nutrient uptake, or withdrawal, by crops. The difference between the total basin inputs and outputs represents nutrients that are retained or processed within the basin while moving from the point of use to the stream, or in the stream. Nitrogen output, as a percentage of the total basin nitrogen inputs, ranged from 19 to 79 percent for instream loads (35 percent mean) and from 0.01 to 32 percent for crop harvest (10 percent mean). From 53 to 87 percent (75 percent mean) of nitrogen inputs were retained within the 18 basins. Phosphorus output ranged from 9 to 29 percent for instream loads (18 percent mean) and from 0.01 to 23 percent for crop harvest (7 percent mean). The basins retained from 60 to 87 percent (74 percent mean) of phosphorous inputs. Correlation of basin nutrient output loads and concentrations with the basin inputs and correlation of output loads and concentrations with basin land use were tested using the Spearman rank test. The correlation analysis indicated that higher nitrogen concentrations in the streams are associated with urban areas and higher loads are associated with agriculture; high phosphorus output loads and concentrations are associated with agriculture. Higher nutrient loads in agricultural basins are partly an effect of basin size-- larger basins generate larger nutrient loads. Nutrient loads and concentrations showed no significant correlation to point-source inputs. Nitrogen loads were significantly (p<0.05, correlation coefficient >0.5) higher in basins with greater cropland areas. Nitrogen concentrations also increased as residential, commercial, and total urban areas increased. Phosphorus loads were positively correlated with animal-waste inputs, pasture, and total agricultural land. Phosphorus concentrations were highest in basins with the greatest amounts of row-crop agriculture.

Linking Landscape Characteristics and High Stream Nitrogen in the Oregon Coast Range: Red Alder Complicates Use of Nutrient Criteria

EPA Science Inventory

Red alder (a nitrogen-fixing tree) and sea salt inputs can strongly influence stream nitrogen concentrations in western Oregon and Washington. We compiled a database of stream nitrogen and landscape characteristics in the Oregon Coast Range. Basal area of alder, expressed as a ...

Effects of water and nitrogen availability on nitrogen contribution by the legume, Lupinus argenteus Pursh

Treesearch

Erin Goergen; Jeanne C. Chambers; Robert Blank

2009-01-01

Nitrogen-fixing species contribute to ecosystem nitrogen budgets, but background resource levels influence nodulation, fixation, and plant growth. We conducted a greenhouse experiment to examine the separate and interacting effects of water and N availability on biomass production, tissue N concentration, nodulation, nodule activity, and rhizodeposition of ...

Organic nitrogen in PM2.5 aerosol at a forest site in the Southeast US

EPA Science Inventory

There is growing evidence that organo-nitrogen compounds may constitute a significant fraction of the aerosol nitrogen (N) budget. In this study, the concentration of organic nitrogen (ON) and major inorganic ions in PM2.5 aerosol were measured at the Duke Forest Research Facilit...

Methodology for estimating nutrient loads discharged from the east coast canals to Biscayne Bay, Miami-Dade County, Florida

USGS Publications Warehouse

Lietz, Arthur C.

1999-01-01

Biscayne Bay is an oligotrophic, subtropical estuary located along the southeastern coast of Florida that provides habitat for a variety of plant and animal life. Concern has arisen with regard to the ecological health of Biscayne Bay because of the presence of nutrient-laden discharges from the east coast canals that drain into the bay. This concern, as well as planned diversion of discharges for ecosystem restoration from the urban and agricultural corridors of Miami-Dade County to Everglades National Park, served as the impetus for a study conducted during the 1996 and 1997 water years to estimate nutrient loads discharged from the east coast canals into Biscayne Bay. Analytical results indicated that the highest concentration of any individual nutrient sampled for in the study was 4.38 mg/L (milligrams per liter) for nitrate at one site, and the lowest concentrations determined were below the detection limits for orthophosphate at six sites and nitrite at four sites. Median concentrations for all the sites were 0.75 mg/L for total organic nitrogen, 0.10 mg/L for ammonia, 0.02 mg/L for nitrite, 0.18 mg/L for nitrate, 0.20 mg/L for nitrite plus nitrate nitrogen, 0.02 mg/L for total phosphorus, and 0.005 mg/L for orthophosphate. The maximum total phosphorus concentration of 0.31 mg/L was the only nutrient concentration to exceed U.S. Environmental Protection Agency (1986) water-quality criteria. High concentrations of total phosphorus usually reflect contamination as a result of human activities. Five sites exceeded the fresh-water quality standard of 0.5 mg/L for ammonia concentration as determined by the Miami-Dade County Department of Environmental Resources Management. Median total organic nitrogen concentrations were higher in urban and forested/wetland areas than in agricultural areas; median concentrations of nitrite, nitrate, and nitrite plus nitrate nitrogen were higher in agricultural areas than in urban and forested/wetland areas; and ammonia, total phosphorus, and orthophosphate concentrations were higher in urban areas than in agricultural and forested/wetland areas. These results coincide with expected differences in nutrient concentrations based on knowledge of point and nonpoint source influences and nutrient cycling. The Wilcoxon signed ranks test (WSRT) was used to compare differences between point (grab) samples and depth-integrated samples for total nitrogen and total phosphorus concentrations at 12 east coast canal sites. Statistically significant differences (alpha level of 0.025) in total phosphorus concentrations between point (grab) samples collected 1.0 meter deep and depth-integrated samples were detected at three sites. One site also showed statistically significant differences in total phosphorus concentrations between point (grab) samples collected 0.5 meter deep and depth-integrated samples. There were no statistically significant differences in total nitrogen and total phosphorus concentrations between point (grab) samples collected 0.5 meter deep and 1.0 meter deep for all the sites. Results of the line of organic correlation, a fitting procedure used to compare point (grab) and depth-integrated samples where statistically significant differences exist as defined by the WSRT, indicated that point (grab) samples underestimate total phosphorus concentrations when compared to depth-integrated samples. This underestimation probably can be attributed to the reduced suspended-sediment concentrations near the surface during periods of flow as compared to those near the streambed. Predictive models were developed to estimate total nitrogen and total phosphorus loads by means of an ordinary least-squares regression technique. Instantaneous discharge was used as the independent variable, and total phosphorus load or total nitrogen load represented the dependent variable. A software program called Estimator was used to develop the regression models and to compute total nitrogen and total phosphorus loads

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

PubMed

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

2017-10-01

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. Copyright © 2017 Elsevier Ltd. All rights reserved.

Sources and distribution of nitrate in ground water at a farmed field irrigated with sewage treatment-plant effluent, Tallahassee, Florida

USGS Publications Warehouse

Berndt, M.P.

1990-01-01

The city of Tallahassee, Florida began applying sewage treatment-plant effluent to a sprayfield southeast of the city in 1980. Fertilizers containing inorganic nitrogen were also applied in conjunction with the operation of a commercial farm at this site. Analysis of groundwater in the surficial aquifer and the Upper Floridan aquifer have indicated that nitrate concentrations in some wells exceed the prescribed drinking water maximum contaminant level of 10 mg/L (nitrate as nitrogen). Nitrate concentrations greater than the maximum contaminant level were not detected in samples from monitoring wells outside the sprayfield boundary. Analyses of water from the unsaturated zone indicated that conversion of organic nitrogen and ammonia to nitrate was complete before the nitrogen- enriched water reached the water table. Groundwater samples from wells in the surficial and Upper Floridan aquifers less than 100 ft deep located inside sprayed areas had mean concentrations of nitrate much higher than samples from similar wells located outside sprayed areas at the southeast sprayfield. These shallow wells inside the sprayed areas were the only wells in which the maximum contaminant level for nitrate was exceeded. Analyses of the nitrogen isotope ratios in groundwater were used to determine whether the major source of nitrogen was treated sewage or fertilizers. The nitrogen isotope ratios in contaminated groundwater at the southeast sprayfield were compared to those at another sprayfield southwest of the city, where treated sewage was the sole source of nitrogen. Statistical analyses indicated a significant difference in the nitrogen isotope ratios at the two sites, indicating that both nitrogen sources are significant at the southeast sprayfield. (USGS)

Use of pharmaceuticals and pesticides to constrain nutrient sources in coastal groundwater of northwestern Long Island, New York, USA

USGS Publications Warehouse

Zhao, S.; Zhang, P.; Crusius, John; Kroeger, K.D.; Bratton, J.F.

2011-01-01

In developed, non-agricultural, unsewered areas, septic systems and fertilizer application to lawns and gardens represent two major sources of nitrogen to coastal groundwater, in addition to atmospheric input. This study was designed to distinguish between these two possible nitrogen sources by analyzing groundwater samples for pharmaceutical residuals, because fertilizers do not contain any of these pharmaceuticals, but domestic wastewater commonly does. In addition, several herbicides and insecticides used in lawn treatment were analyzed as indicators of nitrogen delivery to groundwater from fertilizers. Groundwater samples were taken through piezometres at shoreline sites in unsewered areas surrounding Northport Harbor and in sewered areas adjacent to Manhasset Bay (hereafter referred to as "Northport" and "Manhasset", respectively), both in northwestern Long Island, USA. Excessive nitrogen loading has led to reduced dissolved oxygen concentrations in Long Island Sound, and the groundwater contribution to the nitrogen budget is poorly constrained. The frequent detection of the anticonvulsant compound carbamazepine in groundwater samples of the Northport Harbor area (unsewered), together with the fact that few pesticides associated with lawn applications were detected, suggests that wastewater input and atmospheric input are the likely sources of nitrogen in the Northport groundwater. High concentrations of nitrogen were also detected in the Manhasset (sewered) groundwater. The low detection frequency and concentration of carbamazepine, however, suggest that the sewer system effectively intercepts nitrogen from wastewater there. The likely sources of nitrogen in the Manhasset groundwater are atmospheric deposition and lawn fertilizers, as this area is densely populated.

Effect of Alnus glutinosa on hybrid populus growth and soil nitrogen concentration in a mixed plantation

Treesearch

Jeffrey O. Dawson; Edward A. Hansen

1983-01-01

Height growth of hybrid Populusand soil nitrogen concentration around Alnus glutinosa stems differed significantly both spatially and with the Alnus/Populus mixture in a short-rotation intensively cultured mixed planting. Populus height growth comparable to that obtained from optimal rates of...

Root yield and quality of sugarbeet hybrids with pollinators selected for sodium, potassium, or amino-nitrogen concentration

USDA-ARS?s Scientific Manuscript database

Sodium, potassium, and amino-nitrogen, collectively referred to as impurities, are natural constituents of sugarbeet that impede sucrose extraction during factory operations. Lines selected specifically for low or high concentration of a single impurity component were crossed as pollinators with a ...

Estimation of forest canopy nitrogen concentration. Chapter 15

Treesearch

Marie-Louise Smith; David Y. Hollinger; Scott Ollinger

2008-01-01

The ability to detect patterns of carbon assimilation by vegetation is a key component of the North American Carbon Program. Because photosynthetic potential is strongly related to biochemical constituents such as nitrogen and chlorophyll concentrations in foliage, the ability to incorporate canopy chemistry into landscape- to regional-scale carbon cycling research...

Tidal Prism Modeling of Phytoplankton and Nitrogen Concentrations in Narragansett Bay and its Sub-Embayments

EPA Science Inventory

A tidal prism model was developed to calculate temporal changes in the spatially averaged concentration of three state variables: phytoplankton, dissolved inorganic nitrogen, and detritus. Our main objective was to develop a model to help us understand the causes of phytoplankton...

Comparing Institution Nitrogen Footprints: Metrics for Assessing and Tracking Environmental Impact

EPA Science Inventory

When multiple institutions with strong sustainability initiatives use a new environmental impact assessment tool, there is an impulse to compare. The first seven institutions to calculate their nitrogen footprints using the nitrogen footprint tool have worked collaboratively to i...

Effect of injection-gas concentration on the electron beam quality from a laser-plasma accelerator

NASA Astrophysics Data System (ADS)

Mirzaie, Mohammad; Zhang, Guobo; Li, Song; Gao, Kai; Li, Guangyu; Ain, Quratul; Hafz, Nasr A. M.

2018-04-01

By using 25-45 TW ultra-short (30 fs) laser pulses, we report on the effect of the injection gas concentration on the quality of electron beams generated by a laser-driven plasma wakefield acceleration employing the ionization-injection. For a plasma formed from helium-nitrogen gas mixture and depending on the concentration of the nitrogen gas, we could distinguish a clear trend for the quality of the generated electron beams in terms of their peak energy, energy-spread, divergence angle, and beam charge. The results clearly showed that the lower the nitrogen concentration, the better the quality (higher peak energy, smaller energy spread, and smaller emittance) of the generated electron beams. The results are in reasonable agreement with two-dimensional particle-in-cell simulations.

Simultaneous efficient removal of high-strength ammonia nitrogen and chemical oxygen demand from landfill leachate by using an extremely high ammonia nitrogen-resistant strain.

PubMed

Yu, Dahai; Yang, Jiyu; Fang, Xuexun; Ren, Hejun

2015-01-01

Bioaugmentation is a promising technology for pollutant elimination from stressed environments, and it would provide an efficient way to solve challenges in traditional biotreatment of wastewater with high strength of ammonia nitrogen (NH4(+)-N). A high NH4(+)-N-resistant bacteria strain, identified as Bacillus cereus (Jlu BC), was domesticated and isolated from the bacteria consortium in landfill leachate. Jlu BC could survive in 100 g/L NH4(+)-N environment, which indicated its extremely high NH4(+)-N tolerance than the stains found before. Jlu BC was employed in the bioaugmented system to remove high strength of NH4(+)-N from landfill leachate, and to increase the removal efficiency, response surface methodology (RSM) was used for optimizing bioaugmentation degradation conditions. At the optimum condition (initial pH 7.33, 4.14 days, initial chemical oxygen demand [COD] concentration [18,000 mg/L], 3.5 mL inoculated domesticated bacteria strain, 0.3 mg/mL phosphorus supplement, 30 °C, and 170 rpm), 94.74 ± 3.8% removal rate of NH4(+)-N was obtained, and the experiment data corresponded well with the predicted removal rate of the RSM models (95.50%). Furthermore, COD removal rate of 81.94 ± 1.4% was obtained simultaneously. The results presented are promising, and the screened strain would be of great practical importance in mature landfill leachate and other NH4(+)-N enrichment wastewater pollution control. © 2014 International Union of Biochemistry and Molecular Biology, Inc.

The distribution of, and relation among, mercury and methylmercury, organic carbon, carbonate, nitrogen and phosphorus, in periphyton of the south florida ecosystem

USGS Publications Warehouse

Simon, N.S.; Spencer, R.; Cox, T.

1999-01-01

Periphyton samples from Water Conservation Areas, Big Cypress National Preserve, and Everglades National Park in south Florida were analyzed for concentrations of total mercury, methylmercury, nitrogen, phosphorus, organic carbon, and inorganic carbon. Concentrations of total mercury in periphyton decrease slightly along a gradient from north-to-south. Both total mercury and methylmercury are positively correlated with organic carbon, nitrogen and phosphorus in periphyton. In horizontal sections of periphyton mats, total mercury concentrations tend to be largest at the tops and bottoms of the mats. Methylmercury concentrations tend to be the largest near the bottom of mats. These localized elevated concentrations of methylmercury suggest that there are "hot spots" of methylmercury in periphyton. ?? 1999 OPA (Overseas Publishers Association) N.V. Published by license under the Gordon and Breach Science Publishers imprint.

Ground-water-quality appraisal of sand-plain aquifers in Hubbard, Morrison, Otter Tail, and Wadena Counties, Minnesota

USGS Publications Warehouse

Myette, C.F.

1984-01-01

Site-specific investigations at the Staples Irrigation Center near Staples, Minnesota, indicate that, in addition to seasonal variation, nitrite plus nitrate nitrogen and chloride concentrations decreased with depth while iron concentrations increased. Although no direct quantifiable relationship between concentration and depth was found, mean nitrite plus nitrate nitrogen and chloride concentrations were both 15 milligrams per liter near the top of the aquifer and were 0.1 and 3.5 milligrams per liter, respectively, near the bottom; mean concentrations of dissolved iron were 460 ug/L near the top of the aquifer and 3840 ug/L near the bottom. Data show that the stratification with depth of nitrite plus nitrate nitrogen, chloride, and iron exists at least several hundred feet from the source area throughout most of the year. Chemical stratification appears to be greatest during periods of little recharge.