Nitrate and Nitrogen Oxides: Sources, Health Effects and Their Remediation.

Science.gov (United States)

Hakeem, Khalid Rehman; Sabir, Muhammad; Ozturk, Munir; Akhtar, Mohd Sayeed; Ibrahim, Faridah Hanum

Increased use of nitrogenous (N) fertilizers in agriculture has significantly altered the global N-cycle because they release nitrogenous gases of environmental concerns. The emission of nitrous oxide (N 2 O) contributes to the global greenhouse gas accumulation and the stratospheric ozone depletion. In addition, it causes nitrate leaching problem deteriorating ground water quality. The nitrate toxicity has been reported in a number of studies showing the health hazards like methemoglobinemia in infants and is a potent cause of cancer. Despite these evident negative environmental as well as health impacts, consumption of N fertilizer cannot be reduced in view of the food security for the teeming growing world population. Various agronomic and genetic modifications have been practiced to tackle this problem. Some agronomic techniques adopted include split application of N, use of slow-release fertilizers, nitrification inhibitors and encouraging the use of organic manure over chemical fertilizers. As a matter of fact, the use of chemical means to remediate nitrate from the environment is very difficult and costly. Particularly, removal of nitrate from water is difficult task because it is chemically non-reactive in dilute aqueous solutions. Hence, the use of biological means for nitrate remediation offers a promising strategy to minimize the ill effects of nitrates and nitrites. One of the important goals to reduce N-fertilizer application can be effectively achieved by choosing N-efficient genotypes. This will ensure the optimum uptake of applied N in a balanced manner and exploring the molecular mechanisms for their uptake as well as metabolism in assimilatory pathways. The objectives of this paper are to evaluate the interrelations which exist in the terrestrial ecosystems between the plant type and characteristics of nutrient uptake and analyze the global consumption and demand for fertilizer nitrogen in relation to cereal production, evaluate the various

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

Science.gov (United States)

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

2013-04-01

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

The influence of rate and time of nitrate supply on nitrogen fixation and yield in pea (Pisum sativum L.)

DEFF Research Database (Denmark)

Jensen, Erik Steen

1986-01-01

contributed with 82, 13 and 5% of total plant N, respectively. The supply of low rates of nitrate fertilizer at sowing (“starter N”) increased the vegetative dry matter production, but not the seed yield significantly. Nitrogen fixation was not significantly decreased by the lower rates of nitrate but higher...

Nitrate-induced changes and effect of varying total nitrogen to total ...

African Journals Online (AJOL)

Microcystis aeruginosa, a common cyanobacterium in Lake Chivero, did not assume dominance in any of the treatments. From an application perspective it is interesting that varying nitrate loadings in microcosms favoured chlorophytes rather than increasing undesirable cyanobacteria. Nutrient manipulation can be used as ...

Intracellular Nitrate of Marine Diatoms as a Driver of Anaerobic Nitrogen Cycling in Sinking Aggregates

Directory of Open Access Journals (Sweden)

Anja Kamp

2016-11-01

Full Text Available Diatom-bacteria aggregates are key for the vertical transport of organic carbon in the ocean. Sinking aggregates also represent pelagic microniches with intensified microbial activity, oxygen depletion in the center, and anaerobic nitrogen cycling. Since some of the aggregate-forming diatom species store nitrate intracellularly, we explored the fate of intracellular nitrate and its availability for microbial metabolism within anoxic diatom-bacteria aggregates. The ubiquitous nitrate-storing diatom Skeletonema marinoi was studied as both axenic cultures and laboratory-produced diatom-bacteria aggregates. Stable 15N isotope incubations under dark and anoxic conditions revealed that axenic S. marinoi is able to reduce intracellular nitrate to ammonium that is immediately excreted by the cells. When exposed to a light:dark cycle and oxic conditions, S. marinoi stored nitrate intracellularly in concentrations > 60 mmol L-1 both as free-living cells and associated to aggregates. Intracellular nitrate concentrations exceeded extracellular concentrations by three orders of magnitude. Intracellular nitrate was used up within 2-3 days after shifting diatom-bacteria aggregates to dark and anoxic conditions. Thirty-one percent of the diatom-derived nitrate was converted to nitrogen gas, indicating that a substantial fraction of the intracellular nitrate pool of S. marinoi becomes available to the aggregate-associated bacterial community. Only 5% of the intracellular nitrate was reduced to ammonium, while 59% was recovered as nitrite. Hence, aggregate-associated diatoms accumulate nitrate from the surrounding water and sustain complex nitrogen transformations, including loss of fixed nitrogen, in anoxic, pelagic microniches. Additionally, it may be expected that intracellular nitrate not converted before the aggregates have settled onto the seafloor could fuel benthic nitrogen transformations.

Ultraviolet irradiation effects incorporation of nitrate and nitrite nitrogen into aquatic natural organic matter

Science.gov (United States)

Thorn, Kevin A.; Cox, Larry G.

2012-01-01

One of the concerns regarding the safety and efficacy of ultraviolet radiation for treatment of drinking water and wastewater is the fate of nitrate, particularly its photolysis to nitrite. In this study, 15N NMR was used to establish for the first time that UV irradiation effects the incorporation of nitrate and nitrite nitrogen into aquatic natural organic matter (NOM). Irradiation of 15N-labeled nitrate in aqueous solution with an unfiltered medium pressure mercury lamp resulted in the incorporation of nitrogen into Suwannee River NOM (SRNOM) via nitrosation and other reactions over a range of pH from approximately 3.2 to 8.0, both in the presence and absence of bicarbonate, confirming photonitrosation of the NOM. The major forms of the incorporated label include nitrosophenol, oxime/nitro, pyridine, nitrile, and amide nitrogens. Natural organic matter also catalyzed the reduction of nitrate to ammonia on irradiation. The nitrosophenol and oxime/nitro nitrogens were found to be susceptible to photodegradation on further irradiation when nitrate was removed from the system. At pH 7.5, unfiltered irradiation resulted in the incorporation of 15N-labeled nitrite into SRNOM in the form of amide, nitrile, and pyridine nitrogen. In the presence of bicarbonate at pH 7.4, Pyrex filtered (cutoff below 290–300 nm) irradiation also effected incorporation of nitrite into SRNOM as amide nitrogen. We speculate that nitrosation of NOM from the UV irradiation of nitrate also leads to production of nitrogen gas and nitrous oxide, a process that may be termed photo-chemodenitrification. Irradiation of SRNOM alone resulted in transformation or loss of naturally abundant heterocyclic nitrogens.

Potential for chlorate interference in ion chromatographic determination of total nitrogen in natural waters following alkaline persulfate digestion.

Science.gov (United States)

Halstead, J A; Edwards, J; Soracco, R J; Armstrong, R W

1999-10-01

Determination of total nitrogen in aqueous samples after thermal potassium peroxydisulfate (persulfate) digestion is a commonly used alternative to the tedious Kjeldahl procedure. When ion chromatography is used to quantify the nitrate formed during digestion, there is a potential for interference from a chlorate peak if the digested sample initially contained chloride in concentrations close to or greater than the concentration of nitrogen. It was determined that this interference can be avoided either by using chromatographic conditions which cleanly resolve the nitrate and chlorate peaks (e.g., the Dionex AG9-HG column) or by using digestion reagent concentrations chosen to maintain a high pH throughout the digestion. The second alternative is not a viable option for investigators using a single digestion for both total nitrogen (TN) and total phosphorus (TP) analysis.

Influence of nitrogen dioxide on the thermal decomposition of ammonium nitrate

Directory of Open Access Journals (Sweden)

Igor L. Kovalenko

2015-06-01

Full Text Available In this paper results of experimental studies of ammonium nitrate thermal decomposition in an open system under normal conditions and in NO2 atmosphere are presented. It is shown that nitrogen dioxide is the initiator of ammonium nitrate self-accelerating exothermic cyclic decomposition process. The insertion of NO2 from outside under the conditions of nonisothermal experiment reduces the characteristic temperature of the beginning of self-accelerating decomposition by 50...70 °C. Using method of isothermal exposures it is proved that thermal decomposition of ammonium nitrate in nitrogen dioxide atmosphere at 210 °C is autocatalytic (zero-order reaction. It was suggested that there is possibility of increasing the sensitivity and detonation characteristics of energy condensed systems based on ammonium nitrate by the insertion of additives which provide an earlier appearance of NO2 in the system.

Forensic applications of nitrogen and oxygen isotopes in tracing nitrate sources in urban environments

Science.gov (United States)

Silva, S.R.; Ging, P.B.; Lee, R.W.; Ebbert, J.C.; Tesoriero, A.J.; Inkpen, E.L.

2002-01-01

Ground and surface waters in urban areas are susceptible to nitrate contamination from septic systems, leaking sewer lines, and fertilizer applications. Source identification is a primary step toward a successful remediation plan in affected areas. In this respect, nitrogen and oxygen isotope ratios of nitrate, in conjunction with hydrologic data and water chemistry, have proven valuable in urban studies from Austin, Texas, and Tacoma, Washington. In Austin, stream water was sampled during stremflow and baseflow conditions to assess surface and subsurface sources of nitrate, respectively. In Tacoma, well waters were sampled in adjacent sewered and un-sewered areas to determine if locally high nitrate concentrations were caused by septic systems in the un-sewered areas. In both studies, sewage was identified as a nitrate source and mixing between sewage and other sources of nitrate was apparent. In addition to source identification, combined nitrogen and oxygen isotopes were important in determining the significance of denitrification, which can complicate source assessment by reducing nitrate concentrations and increasing ??15N values. The two studies illustrate the value of nitrogen and oxygen isotopes of nitrate for forensic applications in urban areas. ?? Published by Elsevier Science Ltd. on behalf of AEHS.

Nitrate reductase activity and its relationship with applied nitrogen in soybean

International Nuclear Information System (INIS)

Ge Wenting; Jin Xijun; Ma Chunmei; Dong Shoukun; Gong Zhenping; Zhang Lei

2011-01-01

Field experiments were conducted to study the nitrate reductase activity and its relationship to nitrogen by using frame tests (pot without bottom), sand culture and 15 N-urea at transplanting in soybean variety Suinong 14. Results showed that the activity of nitrate reductase in leaf changed as a signal peak curve with the soybean growth, lower in vegetative growth phase, higher in reproductive growth period and reached the peak in blooming period, then decreased gradually. Nitrogen application showed obvious effect on the nitrate reductase activity. The activities of nitrate reductase in leaves followed the order of N 135 > N 90 > N 45 > N 0 in vegetative growth stage, no clear regularity was found during the whole reproductive growth period. The activities of nitrate reductase in leaves were accorded with the order of upper leaves > mid leaves > lower leaves, and it was very significant differences (P 15 N labeling method during beginning seed stage and full seed stage shown that 15 N abundance in various organs at different node position also followed the same order, suggesting that high level of nitrate reductase activity at upper leaves of soybean promoted the assimilation of NO 3 - . (authors)

The influence of nitrate and ammonia nitrogen on the photosynthetic ...

African Journals Online (AJOL)

A study has been made on the influence of nitrate and ammonia nitrogen on the carbon dioxide compensation point (T), carboxylating enzymes and growth of highveld grasses found at the primary, secondary and climax successional stages. The results obtained are discussed in relation to the influence of nitrogen on ...

Estimation of nitrate and nitrogen forms of vegetables by UV-spectrophotometry after photo-oxydation.

Science.gov (United States)

Ribeiro, T; Depres, S; Couteau, G; Pauss, A

2003-01-01

An alternative method for the estimation of nitrate and nitrogen forms in vegetables is proposed. Nitrate can be directly estimated by UV-spectrophotometry after an extraction step with water. The other nitrogen compounds are photo-oxidized into nitrate, and then estimated by UV-spectrophotometry. An oxidative solution of sodium persulfate and a Hg-UV lamp is used. Preliminary assays were realized with vegetables like salade, spinachs, artichokes, small peas, broccolis, carrots, watercress; acceptable correlations between expected and experimental values of nitrate amounts were obtained, while the detection limit needs to be lowered. The optimization of the method is underway.

Nitrogen-isotope ratios of nitrate in ground water under fertilized fields, Long Island, New York

Science.gov (United States)

Flipse, W.J.; Bonner, F.T.

1985-01-01

Ground-water samples from two heavily fertilized sites in Suffolk County, New York, were collected through the 1978 growing season and analyzed for nitrate-N concentrations and nitrogen-isotope ratios. Six wells were at a potato farm; six were on a golf course. The purpose of this study was to determine whether the 15N/14N ratios (??15N values) of fertilizer are increased during transit from land surface to ground water to an extent which would preclude use of this ratio to distinguish agricultural from animal sources of nitrate in ground water. Ground water at both sites contained a greater proportion of 15N than the fertilizers being applied. At the potato farm, the average ??15N value of the fertilizers was 0.2???; the average ??15N value of the ground-water nitrate was 6.2???. At the golf course, the average ??15N value of the fertilizers was -5.9???, and that of ground-water nitrate was 6.5???. The higher ??15N values of ground-water nitrate are probably caused by isotopic fractionation during the volatile loss of ammonia from nitrogen applied in reduced forms (NH4+ and organic-N). The ??15N values of most ground-water samples from both areas were less than 10???, the upper limit of the range characteristic of agricultural sources of nitrate; these sources include both fertilizer nitrate and nitrate derived from increased mineralization of soil nitrogen through cultivation. Previous studies have shown that the ??15N values of nitrate derived from human or animal waste generally exceed 10???. The nitrogen-isotope ratios of fertilizer-derived nitrate were not altered to an extent that would make them indistinguishable from animal-waste-derived nitrates in ground water.Ground-water samples from two heavily fertilized sites in Suffolk County, New York, were collected through the 1978 growing season and analyzed for nitrate-N concentrations and nitrogen-isotope ratios. Six wells were at a potato farm; six were on a golf course. The purpose of this study was to

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

International Nuclear Information System (INIS)

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

1974-01-01

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

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

DEFF Research Database (Denmark)

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

2016-01-01

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

Management, regulation and environmental impacts of nitrogen fertilization in Northwestern Europe under the Nitrates Directive

DEFF Research Database (Denmark)

van Grinsven, H.; ten Berge, H.; Dalgaard, Tommy

2012-01-01

Implementation of the Nitrates Directive (NiD) and its environmental impacts were compared for member states in the Northwest of the European Union (Ireland, UK, Denmark, The Netherlands, Belgium, Northern France and Germany). The main sources of data were national reports for the third reporting......D remains an important piece of legislation for protecting drinking water quality in regions with many private or small public production facilities and controlling aquatic eutrophication from agricultural sources....... of concern and improvement of the implementation of the NiD are accounting for the fertilizer value of nitrogen in manure, and relating application limits for total nitrogen (N) to potential crop yield and N removal. The most significant environmental effect of the implementation of the NiD since 1995...... for groundwater in view of delayed response of nitrate in deep aquifers. In spite of improved fertilization practices, the southeast of The Netherlands, the Flemish Region and Brittany remain to be regions of major concern in view of a combination of a high nitrogen surplus, high leaching fractions to groundwater...

Nitrate-Nitrogen Leaching and Modeling in Intensive Agriculture Farmland in China

Directory of Open Access Journals (Sweden)

Ligang Xu

2013-01-01

Full Text Available Protecting water resources from nitrate-nitrogen (NO3-N contamination is an important public health concern and a major national environmental issue in China. Loss of NO3-N in soils due to leaching is not only one of the most important problems in agriculture farming, but is also the main factor causing nitrogen pollution in aquatic environments. Three typical intensive agriculture farmlands in Jiangyin City in China are selected as a case study for NO3-N leaching and modeling in the soil profile. In this study, the transport and fate of NO3-N within the soil profile and nitrate leaching to drains were analyzed by comparing field data with the simulation results of the LEACHM model. Comparisons between measured and simulated data indicated that the NO3-N concentrations in the soil and nitrate leaching to drains are controlled by the fertilizer practice, the initial conditions and the rainfall depth and distribution. Moreover, the study reveals that the LEACHM model gives a fair description of the NO3-N dynamics in the soil and subsurface drainage at the field scale. It can also be concluded that the model after calibration is a useful tool to optimize as a function of the combination “climate-crop-soil-bottom boundary condition” the nitrogen application strategy resulting for the environment in an acceptable level of nitrate leaching. The findings in this paper help to demonstrate the distribution and migration of nitrogen in intensive agriculture farmlands, as well as to explore the mechanism of groundwater contamination resulting from agricultural activities.

Nitrate-Nitrogen Leaching and Modeling in Intensive Agriculture Farmland in China

Science.gov (United States)

Xu, Ligang; Xu, Jin

2013-01-01

Protecting water resources from nitrate-nitrogen (NO3-N) contamination is an important public health concern and a major national environmental issue in China. Loss of NO3-N in soils due to leaching is not only one of the most important problems in agriculture farming, but is also the main factor causing nitrogen pollution in aquatic environments. Three typical intensive agriculture farmlands in Jiangyin City in China are selected as a case study for NO3-N leaching and modeling in the soil profile. In this study, the transport and fate of NO3-N within the soil profile and nitrate leaching to drains were analyzed by comparing field data with the simulation results of the LEACHM model. Comparisons between measured and simulated data indicated that the NO3-N concentrations in the soil and nitrate leaching to drains are controlled by the fertilizer practice, the initial conditions and the rainfall depth and distribution. Moreover, the study reveals that the LEACHM model gives a fair description of the NO3-N dynamics in the soil and subsurface drainage at the field scale. It can also be concluded that the model after calibration is a useful tool to optimize as a function of the combination “climate-crop-soil-bottom boundary condition” the nitrogen application strategy resulting for the environment in an acceptable level of nitrate leaching. The findings in this paper help to demonstrate the distribution and migration of nitrogen in intensive agriculture farmlands, as well as to explore the mechanism of groundwater contamination resulting from agricultural activities. PMID:23983629

Effect of Nitrogen Form and pH of Nutrient Solution on the Shoot Concentration of Phosphorus, Nitrate, and Nitrogen of Spinach in Hydroponic Culture

OpenAIRE

N. Najafi; M. Parsazadeh

2010-01-01

In order to study the effect of nitrogen form and pH of nutrient solution on the shoot concentration of P, nitrate, organic N + inorganic ammonium, and total N of spinach, a factorial experiment was conducted with two factors including pH of nutrient solution in three levels (4.5, 6.5 and 8.0) and nitrate to ammonium ratio of nutrient solution in five levels (100:0, 75:25, 50:50, 25:75 and 0:100). This factorial experiment was carried out in a completely randomized design with four replicatio...

Effectiveness of Ammonium-Nitrogen and Nitrate-Nitrogen in Irrigation Water in Paddy Rice without Topdressed Nitrogen at the Panicle Formation Stage

OpenAIRE

池田, 元輝; 渡辺, 孝賢; Ikeda, Motoki; Watanabe, Takayasu

2002-01-01

A pot experiment was conducted to evaluate the efficiency of ammonium- and nitrate- nitrogen contained in irrigation water during the reproductive growth period of paddy rice （Oryza sativa L. cv. Hinohikari） that did not receive topdressed nitrogen at the panicle formation stage. lrrigation of water containing a low level of nitrogen （7mgNL^-1） did not increase yields so much compared to topdressed nitrogen. lrrigation of water containing a high level of nitrogen （14mgNL^-1） caused substantia...

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

Energy Technology Data Exchange (ETDEWEB)

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

1974-01-01

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

Distribution and Sources of Nitrate-Nitrogen in Kansas Groundwater

Directory of Open Access Journals (Sweden)

Margaret A. Townsend

2001-01-01

Full Text Available Kansas is primarily an agricultural state. Irrigation water and fertilizer use data show long- term increasing trends. Similarly, nitrate-N concentrations in groundwater show long-term increases and exceed the drinking-water standard of 10 mg/l in many areas. A statistical analysis of nitrate-N data collected for local and regional studies in Kansas from 1990 to 1998 (747 samples found significant relationships between nitrate-N concentration with depth, age, and geographic location of wells. Sources of nitrate-N have been identified for 297 water samples by using nitrogen stable isotopes. Of these samples, 48% showed fertilizer sources (+2 to +8 and 34% showed either animal waste sources (+10 to +15 with nitrate-N greater than 10 mg/l or indication that enrichment processes had occurred (+10 or above with variable nitrate-N or both. Ultimate sources for nitrate include nonpoint sources associated with past farming and fertilization practices, and point sources such as animal feed lots, septic systems, and commercial fertilizer storage units. Detection of nitrate from various sources in aquifers of different depths in geographically varied areas of the state indicates that nonpoint and point sources currently impact and will continue to impact groundwater under current land uses.

Triple nitrate isotopes indicate differing nitrate source contributions to streams across a nitrogen saturation gradient

Science.gov (United States)

Lucy A. Rose; Emily M. Elliott; Mary Beth. Adams

2015-01-01

Nitrogen (N) deposition affects forest biogeochemical cycles worldwide, often contributing to N saturation. Using long-term (>30-year) records of stream nitrate (NO3-) concentrations at Fernow Experimental Forest (West Virginia, USA), we classified four watersheds into N saturation stages ranging from Stage 0 (N-...

Nitrate photolysis in salty snow

Science.gov (United States)

Donaldson, D. J.; Morenz, K.; Shi, Q.; Murphy, J. G.

2016-12-01

Nitrate photolysis from snow can have a significant impact on the oxidative capacity of the local atmosphere, but the factors affecting the release of gas phase products are not well understood. Here, we report the first systematic study of the amounts of NO, NO2, and total nitrogen oxides (NOy) emitted from illuminated snow samples as a function of both nitrate and total salt (NaCl and Instant Ocean) concentration. We show that the release of nitrogen oxides to the gas phase is directly related to the expected nitrate concentration in the brine at the surface of the snow crystals, increasing to a plateau value with increasing nitrate, and generally decreasing with increasing NaCl or Instant Ocean (I.O.). In frozen mixed nitrate (25 mM) - salt (0-500 mM) solutions, there is an increase in gas phase NO2 seen at low added salt amounts: NO2 production is enhanced by 35% at low prefreezing [NaCl] and by 70% at similar prefreezing [I.O.]. Raman microscopy of frozen nitrate-salt solutions shows evidence of stronger nitrate exclusion to the air interface in the presence of I.O. than with added NaCl. The enhancement in nitrogen oxides emission in the presence of salts may prove to be important to the atmospheric oxidative capacity in polar regions.

Assessing total nitrogen in surface-water samples--precision and bias of analytical and computational methods

Science.gov (United States)

Rus, David L.; Patton, Charles J.; Mueller, David K.; Crawford, Charles G.

2013-01-01

The characterization of total-nitrogen (TN) concentrations is an important component of many surface-water-quality programs. However, three widely used methods for the determination of total nitrogen—(1) derived from the alkaline-persulfate digestion of whole-water samples (TN-A); (2) calculated as the sum of total Kjeldahl nitrogen and dissolved nitrate plus nitrite (TN-K); and (3) calculated as the sum of dissolved nitrogen and particulate nitrogen (TN-C)—all include inherent limitations. A digestion process is intended to convert multiple species of nitrogen that are present in the sample into one measureable species, but this process may introduce bias. TN-A results can be negatively biased in the presence of suspended sediment, and TN-K data can be positively biased in the presence of elevated nitrate because some nitrate is reduced to ammonia and is therefore counted twice in the computation of total nitrogen. Furthermore, TN-C may not be subject to bias but is comparatively imprecise. In this study, the effects of suspended-sediment and nitrate concentrations on the performance of these TN methods were assessed using synthetic samples developed in a laboratory as well as a series of stream samples. A 2007 laboratory experiment measured TN-A and TN-K in nutrient-fortified solutions that had been mixed with varying amounts of sediment-reference materials. This experiment identified a connection between suspended sediment and negative bias in TN-A and detected positive bias in TN-K in the presence of elevated nitrate. A 2009–10 synoptic-field study used samples from 77 stream-sampling sites to confirm that these biases were present in the field samples and evaluated the precision and bias of TN methods. The precision of TN-C and TN-K depended on the precision and relative amounts of the TN-component species used in their respective TN computations. Particulate nitrogen had an average variability (as determined by the relative standard deviation) of 13

The importance of dissimilatory nitrate reduction to ammonium (DNRA) in the nitrogen cycle of coastal ecosystems

DEFF Research Database (Denmark)

Giblin, Anne E.; Tobias, Craig R.; Song, Bongkeun

2013-01-01

Until recently, it was believed that biological assimilation and gaseous nitrogen (N) loss through denitrification were the two major fates of nitrate entering or produced within most coastal ecosystems. Denitrification is often viewed as an important ecosystem service that removes reactive N from...... the ecosystem. However, there is a competing nitrate reduction process, dissimilatory nitrate reduction to ammonium (DNRA), that conserves N within the ecosystem. The recent application of nitrogen stable isotopes as tracers has generated growing evidence that DNRA is a major nitrogen pathway that cannot...... of denitrification and DNRA, and how the balance changes with increased nitrogen loading, is of critical importance for predicting eutrophication trajectories. Recent improvements in methods for assessing rates of DNRA have helped refine our understanding of the rates and controls of this process, but accurate...

Isotope studies on the comparative efficiency of nitrogenous sources

Energy Technology Data Exchange (ETDEWEB)

Dev, G; Rennie, D A [Saskatchewan Univ., Saskatoon (Canada). Dept. of Soil Science

1979-03-01

In a growth chamber experiment with /sup 15/N-labelled potassium nitrate, ammonium sulphate and urea at 75 and 150kg nitrogen/ha and ammonium nitrate at 150kg nitrogen/ha, nitrogen application produced significant responses of dry matter yield and total nitrogen uptake by shoot and root of barley in chernozemic dark brown Elstow silt loam and deep black Hoey clay soil. Total nitrogen removal per pot and isotope-derived criteria, viz. percentage nitrogen derived from fertilizer, 'A' value and percentage fertilizer nitrogen utilization, indicated that potassium nitrate was the most efficient and urea the least.

Coupling of oceanic carbon and nitrogen: A window to spatially resolved quantitative reconstruction of nitrate inventories

Science.gov (United States)

Glock, N.; Liebetrau, V.; Gorb, S.; Wallmann, K. J. G.; Erdem, Z.; Schönfeld, J.; Eisenhauer, A.

2017-12-01

Anthropogenic impact has led to a severe acceleration of the global nitrogen cycle. Every second nitrogen atom in the biosphere may now originate from anthropogenic sources such as chemical fertilizers and the burning of fossil fuels. A quantitative reconstruction of past reactive nitrogen inventories is invaluable to facilitate projections for future scenarios and calibrations for such paleoproxies should be done as long the natural signature is still visible. Here we present a first quantitative reconstruction of nitrate concentrations in intermediate water depths of the Peruvian oxygen minimum zone over the last deglaciation using the pore density in the benthic foraminiferal species Bolivina spissa. A comparison of the nitrate reconstruction to the stable carbon isotope (δ13C) record reveals a strong coupling between the carbon and nitrogen cycles. The linear correlation between δ13C and nitrate availability remained stable over the last 22,000 years, facilitating the use of δ13C records as a quantitative nitrate proxy. The combination of the pore density record with δ13C records shows an elevated oceanic nitrate inventory during the Last Glacial Maximum as compared to the Holocene. Our novel proxy approach is consistent with the results of previous δ15N-based biogeochemical modeling studies, and thus provides sound estimates of the nitrate inventory in the glacial and deglacial ocean.

Nitrate signals determine the sensing of nitrogen through differential expression of genes involved in nitrogen uptake and assimilation in finger millet.

Science.gov (United States)

Gupta, Alok Kumar; Gaur, Vikram Singh; Gupta, Sanjay; Kumar, Anil

2013-06-01

In order to understand the molecular basis of high nitrogen use efficiency of finger millet, five genes (EcHNRT2, EcLNRT1, EcNADH-NR, EcGS, and EcFd-GOGAT) involved in nitrate uptake and assimilation were isolated using conserved primer approaches. Expression profiles of these five genes along with the previously isolated EcDof1 was studied under increased KNO3 concentrations (0.15 to 1,500 μM) for 2 h as well as at 1.5 μM for 24 h in the roots and shoots of 25 days old nitrogen deprived two contrasting finger millet genotypes (GE-3885 and GE-1437) differing in grain protein content (13.76 and 6.15 %, respectively). Time kinetics experiment revealed that, all the five genes except EcHNRT2 in the leaves of GE-3885 were induced within 30 min of nitrate exposure indicating that there might be a greater nitrogen deficit in leaves and therefore quick transportation of nitrate signals to the leaves. Exposing the plants to increasing nitrate concentrations for 2 h showed that in roots of GE-3885, NR was strongly induced while GS was repressed; however, the pattern was found to be reversed in leaves of GE-1437 indicating that in GE-3885, most of the nitrate might be reduced in the roots but assimilated in leaves and vice-versa. Furthermore, compared with the low-protein genotype, expression of HNRT2 was strongly induced in both roots and shoots of high-protein genotype at the least nitrate concentration supplied. This further indicates that GE-3885 is a quick sensor of nitrogen compared with the low-protein genotype. Furthermore, expression of EcDof1 was also found to overlap the expression of NR, GS, and GOGAT indicating that Dof1 probably regulates the expression of these genes under different conditions by sensing the nitrogen fluctuations around the root zone.

Adsorptive Removal of Nitrate from Aqueous Solution Using Nitrogen Doped Activated Carbon.

Science.gov (United States)

Machida, Motoi; Goto, Tatsuru; Amano, Yoshimasa; Iida, Tatsuya

2016-01-01

Activated carbon (AC) has been widely applied for adsorptive removal of organic contaminants from aqueous phase, but not for ionic pollutants. In this study, nitrogen doped AC was prepared to increase the adsorption capacity of nitrate from water. AC was oxidized with (NH 4 ) 2 S 2 O 8 solution to maximize oxygen content for the first step, and then NH 3 gas treatment was carried out at 950°C to aim at forming quaternary nitrogen (N-Q) species on AC surface (Ox-9.5AG). Influence of solution pH was examined so as to elucidate the relationship between surface charge and adsorption amounts of nitrate. The results showed that Ox-9.5AG exhibited about twice higher adsorption capacity than non-treatment AC at any initial nitrate concentration and any equilibrium solution pH (pH e ) investigated. The more decrease in pH e value, the more adsorption amount of negatively charged nitrate ion, because the surface charge of AC and Ox-9.5AG could become more positive in acidic solution. The oxidation and consecutive ammonia treatments lead to increase in nitrogen content from 0.35 to 6.4% and decrease in the pH of the point of zero charge (pH pzc ) from 7.1 to 4.0 implying that positively charged N-Q of a Lewis acid was created on the surface of Ox-9.5AG. Based on a Langmuir data analysis, maximum adsorption capacity attained 0.5-0.6 mmol/g of nitrate and adsorption affinity was 3.5-4.0 L/mmol at pH e 2.5 for Ox-9.5AG.

Influence of nitrogen dioxide on the thermal decomposition of ammonium nitrate

OpenAIRE

Igor L. Kovalenko

2015-01-01

In this paper results of experimental studies of ammonium nitrate thermal decomposition in an open system under normal conditions and in NO2 atmosphere are presented. It is shown that nitrogen dioxide is the initiator of ammonium nitrate self-accelerating exothermic cyclic decomposition process. The insertion of NO2 from outside under the conditions of nonisothermal experiment reduces the characteristic temperature of the beginning of self-accelerating decomposition by 50...70 °C. Using metho...

Effect of nitrogen concentration of urea ammonium nitrate, and ...

African Journals Online (AJOL)

Liquid urea ammonium nitrate (UAN) was applied to dryland Pennisetum clandestinum (Kikuyu (Chiov)) and Cynodon hybrid (Coastcross II (L.) (Pers.)) pastures at two levels (207 and 414 kg N/ha/season) and at three concentrations (10, 5; 21 and 42% N) of nitrogen. The degree of leaf scorch increased as both the amount ...

Nitrogen balance and groundwater nitrate contamination: Comparison among three intensive cropping systems on the North China Plain

Energy Technology Data Exchange (ETDEWEB)

Ju, X.T. [Key Laboratory of Plant-Soil Interactions, Ministry of Education, College of Agricultural Resources and Environmental Sciences, China Agricultural University, Beijing 100094 (China); Kou, C.L. [Key Laboratory of Plant-Soil Interactions, Ministry of Education, College of Agricultural Resources and Environmental Sciences, China Agricultural University, Beijing 100094 (China); Institute of Soils and Fertilizers, Henan Academy of Agricultural Sciences, Zhengzhou 450002 (China); Zhang, F.S. [Key Laboratory of Plant-Soil Interactions, Ministry of Education, College of Agricultural Resources and Environmental Sciences, China Agricultural University, Beijing 100094 (China)]. E-mail: zfs@cau.edu.cn; Christie, P. [Key Laboratory of Plant-Soil Interactions, Ministry of Education, College of Agricultural Resources and Environmental Sciences, China Agricultural University, Beijing 100094 (China); Agricultural and Environmental Science Department, Queen' s University Belfast, Belfast BT9 5PX (United Kingdom)

2006-09-15

The annual nitrogen (N) budget and groundwater nitrate-N concentrations were studied in the field in three major intensive cropping systems in Shandong province, north China. In the greenhouse vegetable systems the annual N inputs from fertilizers, manures and irrigation water were 1358, 1881 and 402 kg N ha{sup -1} on average, representing 2.5, 37.5 and 83.8 times the corresponding values in wheat (Triticum aestivum L.)-maize (Zea mays L.) rotations and 2.1, 10.4 and 68.2 times the values in apple (Malus pumila Mill.) orchards. The N surplus values were 349, 3327 and 746 kg N ha{sup -1}, with residual soil nitrate-N after harvest amounting to 221-275, 1173 and 613 kg N ha{sup -1} in the top 90 cm of the soil profile and 213-242, 1032 and 976 kg N ha{sup -1} at 90-180 cm depth in wheat-maize, greenhouse vegetable and orchard systems, respectively. Nitrate leaching was evident in all three cropping systems and the groundwater in shallow wells (<15 m depth) was heavily contaminated in the greenhouse vegetable production area, where total N inputs were much higher than crop requirements and the excessive fertilizer N inputs were only about 40% of total N inputs. - Intensive greenhouse vegetable production systems may pose a greater nitrogen pollution threat than apple orchards or cereal rotations to soil and water quality in north China.

Nitrogen balance and groundwater nitrate contamination: Comparison among three intensive cropping systems on the North China Plain

International Nuclear Information System (INIS)

Ju, X.T.; Kou, C.L.; Zhang, F.S.; Christie, P.

2006-01-01

The annual nitrogen (N) budget and groundwater nitrate-N concentrations were studied in the field in three major intensive cropping systems in Shandong province, north China. In the greenhouse vegetable systems the annual N inputs from fertilizers, manures and irrigation water were 1358, 1881 and 402 kg N ha -1 on average, representing 2.5, 37.5 and 83.8 times the corresponding values in wheat (Triticum aestivum L.)-maize (Zea mays L.) rotations and 2.1, 10.4 and 68.2 times the values in apple (Malus pumila Mill.) orchards. The N surplus values were 349, 3327 and 746 kg N ha -1 , with residual soil nitrate-N after harvest amounting to 221-275, 1173 and 613 kg N ha -1 in the top 90 cm of the soil profile and 213-242, 1032 and 976 kg N ha -1 at 90-180 cm depth in wheat-maize, greenhouse vegetable and orchard systems, respectively. Nitrate leaching was evident in all three cropping systems and the groundwater in shallow wells (<15 m depth) was heavily contaminated in the greenhouse vegetable production area, where total N inputs were much higher than crop requirements and the excessive fertilizer N inputs were only about 40% of total N inputs. - Intensive greenhouse vegetable production systems may pose a greater nitrogen pollution threat than apple orchards or cereal rotations to soil and water quality in north China

Contribution of the isotopic study of nitrogen to the knowledge of the pollution of underground aquifers by nitrates, in agricultural environment (Brie, Beauce - France)

International Nuclear Information System (INIS)

Mariotti, A.; Ben Halima, A.; Berger, G.

1976-01-01

Isotope composition of nitrate nitrogen from aquifers in the highly cultivated areas from Brie and Beauce show three different nitrogen inputs: nitrate from organic matter in soils; nitrate from fertilizers; nitrate from domestic and animal wastes. The isotope composition of those stocks are different enough to trace their origin and establish material balances of nitrogen pollution [fr

Airborne observations of total RONO2: new constraints on the yield and lifetime of isoprene nitrates

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W. H. Brune

2009-02-01

Full Text Available Formation of isoprene nitrates (INs is an important free radical chain termination step ending production of ozone and possibly affecting formation of secondary organic aerosol. Isoprene nitrates also represent a potentially large, unmeasured contribution to OH reactivity and are a major pathway for the removal of nitrogen oxides from the atmosphere. Current assessments indicate that formation rates of isoprene nitrates are uncertain to a factor of 2–3 and the subsequent fate of isoprene nitrates remains largely unconstrained by laboratory, field or modeling studies. Measurements of total alkyl and multifunctional nitrates (ΣANs, NO2, total peroxy nitrates (ΣPNs, HNO3, CH2O, isoprene and other VOC were obtained from the NASA DC-8 aircraft during summer 2004 over the continental US during the INTEX-NA campaign. These observations represent the first characterization of ΣANs over a wide range of land surface types and in the lower free troposphere. ΣANs were a significant, 12–20%, fraction of NOy throughout the experimental domain and ΣANs were more abundant when isoprene was high. We use the observed hydrocarbon species to calculate the relative contributions of ΣAN precursors to their production. These calculations indicate that isoprene represents at least three quarters of the ΣAN source in the summertime continental boundary layer of the US. An observed correlation between ΣANs and CH2O is used to place constraints on nitrate yields from isoprene oxidation, atmospheric lifetimes of the resulting nitrates and recycling efficiencies of nitrates during subsequent oxidation. We find reasonable fits to the data using sets of production rates, lifetimes and recycling efficiencies of INs as follows (4.4%, 16 h, 97%, (8%, 2.5 h, 79% and (12%, 95 min, 67%. The analysis indicates that the lifetime of ΣANs as a pool of compounds is considerably longer than the lifetime of the individual isoprene nitrates to reaction with OH, implying that

Nitrogen fertilization plans for the main crops of Turkey to mitigate nitrates pollution

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Theodore Karyotis

2014-01-01

Full Text Available To create a rational nitrogen fertilization plan, a mass nitrogen (N balance was used for the main crops of Turkey. The following components are included in the suggested N fertilization plans: the quantity of N fertilizer which is required by the crop for a targeted and sustainable yield, nitrogen inputs available to the crop without fertilization, nitrogen losses mainly due to nitrates leaching and emissions to the atmosphere. This simple equation was transformed to a more detailed one and fertilization plans are based on the total N required to produce a crop of a targeted yield, N mineralized from Soil Organic Matter (SOM, the residual plant available inorganic N before sowing or planting, input of nitrogen from rainfall and losses through leaching and emissions. This work is based on available data and is an open sheet balance which can be easily used by local authorities. Decreased N fertilization can be applied without significant yield reduction and this can be explained by increased N use efficiency, as a result of proper time of application and splitting of N fertilizers in doses. This model can be appropriately adapted according to site-specific conditions, whilst new parameters can be added to improve precision of the performed calculations.

Modeling nitrate leaching and optimizing water and nitrogen management under irrigated maize in desert oases in Northwestern China.

Science.gov (United States)

Hu, Kelin; Li, Yong; Chen, Weiping; Chen, Deli; Wei, Yongping; Edis, Robert; Li, Baoguo; Huang, Yuanfang; Zhang, Yuanpei

2010-01-01

Understanding water and N transport through the soil profile is important for efficient irrigation and nutrient management to minimize nitrate leaching to the groundwater, and to promote agricultural sustainable development in desert oases. In this study, a process-based water and nitrogen management model (WNMM) was used to simulate soil water movement, nitrate transport, and crop growth (maize [Zea mays L.]) under desert oasis conditions in northwestern China. The model was calibrated and validated with a field experiment. The model simulation results showed that about 35% of total water input and 58% of the total N input were leached to <1.8 m depth under traditional management practice. Excessive irrigation and N fertilizer application, high nitrate concentration in the irrigation water, together with the sandy soil texture, resulted in large nitrate leaching. Nitrate leaching was significantly reduced under the improved management practice suggested by farm extension personnel; however, the water and nitrate inputs still far exceeded the crop requirements. More than 1700 scenarios combining various types of irrigation and fertilizer practices were simulated. Quantitative analysis was conducted to obtain the best management practices (BMPs) with simultaneous consideration of crop yield, water use efficiency, fertilizer N use efficiency, and nitrate leaching. The results indicated that the BMPs under the specific desert oasis conditions are to irrigate the maize with 600 mm of water in eight times with a single fertilizer application at a rate of 75 kg N ha(-1).

Dissimilatory nitrogen reduction in intertidal sediments of a temperate estuary: small scale heterogeneity and novel nitrate-to-ammonium reducers.

Directory of Open Access Journals (Sweden)

Helen eDecleyre

2015-10-01

Full Text Available The estuarine nitrogen cycle can be substantially altered due to anthropogenic activities resulting in increased amounts of inorganic nitrogen (mainly nitrate. In the past, denitrification was considered to be the main ecosystem process removing reactive nitrogen from the estuarine ecosystem. However, recent reports on the contribution of dissimilatory nitrate reduction to ammonium (DNRA to nitrogen removal in these systems indicated a similar or higher importance, although the ratio between both processes remains ambiguous. Compared to denitrification, DNRA has been underexplored for the last decades and the key organisms carrying out the process in marine environments are largely unknown. Hence, as a first step to better understand the interplay between denitrification, DNRA and reduction of nitrate to nitrite in estuarine sediments, nitrogen reduction potentials were determined in sediments of the Paulina polder mudflat (Westerschelde estuary. We observed high variability in dominant nitrogen removing processes over a short distance (1.6 m, with nitrous oxide, ammonium and nitrite production rates differing significantly between all sampling sites. Denitrification occurred at all sites, DNRA was either the dominant process (two out of five sites or absent, while nitrate reduction to nitrite was observed in most sites but never dominant. In addition, novel nitrate-to-ammonium reducers assigned to Thalassospira, Celeribacter and Halomonas, for which DNRA was thus far unreported, were isolated, with DNRA phenotype reconfirmed through nrfA gene amplification. This study demonstrates high small scale heterogeneity among dissimilatory nitrate reduction processes in estuarine sediments and provides novel marine DNRA organisms that represent valuable alternatives to the current model organisms.

Dissimilatory nitrogen reduction in intertidal sediments of a temperate estuary: small scale heterogeneity and novel nitrate-to-ammonium reducers.

Science.gov (United States)

Decleyre, Helen; Heylen, Kim; Van Colen, Carl; Willems, Anne

2015-01-01

The estuarine nitrogen cycle can be substantially altered due to anthropogenic activities resulting in increased amounts of inorganic nitrogen (mainly nitrate). In the past, denitrification was considered to be the main ecosystem process removing reactive nitrogen from the estuarine ecosystem. However, recent reports on the contribution of dissimilatory nitrate reduction to ammonium (DNRA) to nitrogen removal in these systems indicated a similar or higher importance, although the ratio between both processes remains ambiguous. Compared to denitrification, DNRA has been underexplored for the last decades and the key organisms carrying out the process in marine environments are largely unknown. Hence, as a first step to better understand the interplay between denitrification, DNRA and reduction of nitrate to nitrite in estuarine sediments, nitrogen reduction potentials were determined in sediments of the Paulina polder mudflat (Westerschelde estuary). We observed high variability in dominant nitrogen removing processes over a short distance (1.6 m), with nitrous oxide, ammonium and nitrite production rates differing significantly between all sampling sites. Denitrification occurred at all sites, DNRA was either the dominant process (two out of five sites) or absent, while nitrate reduction to nitrite was observed in most sites but never dominant. In addition, novel nitrate-to-ammonium reducers assigned to Thalassospira, Celeribacter, and Halomonas, for which DNRA was thus far unreported, were isolated, with DNRA phenotype reconfirmed through nrfA gene amplification. This study demonstrates high small scale heterogeneity among dissimilatory nitrate reduction processes in estuarine sediments and provides novel marine DNRA organisms that represent valuable alternatives to the current model organisms.

Nitrate radical oxidation of γ-terpinene: hydroxy nitrate, total organic nitrate, and secondary organic aerosol yields

Science.gov (United States)

Slade, Jonathan H.; de Perre, Chloé; Lee, Linda; Shepson, Paul B.

2017-07-01

Polyolefinic monoterpenes represent a potentially important but understudied source of organic nitrates (ONs) and secondary organic aerosol (SOA) following oxidation due to their high reactivity and propensity for multi-stage chemistry. Recent modeling work suggests that the oxidation of polyolefinic γ-terpinene can be the dominant source of nighttime ON in a mixed forest environment. However, the ON yields, aerosol partitioning behavior, and SOA yields from γ-terpinene oxidation by the nitrate radical (NO3), an important nighttime oxidant, have not been determined experimentally. In this work, we present a comprehensive experimental investigation of the total (gas + particle) ON, hydroxy nitrate, and SOA yields following γ-terpinene oxidation by NO3. Under dry conditions, the hydroxy nitrate yield = 4(+1/-3) %, total ON yield = 14(+3/-2) %, and SOA yield ≤ 10 % under atmospherically relevant particle mass loadings, similar to those for α-pinene + NO3. Using a chemical box model, we show that the measured concentrations of NO2 and γ-terpinene hydroxy nitrates can be reliably simulated from α-pinene + NO3 chemistry. This suggests that NO3 addition to either of the two internal double bonds of γ-terpinene primarily decomposes forming a relatively volatile keto-aldehyde, reconciling the small SOA yield observed here and for other internal olefinic terpenes. Based on aerosol partitioning analysis and identification of speciated particle-phase ON applying high-resolution liquid chromatography-mass spectrometry, we estimate that a significant fraction of the particle-phase ON has the hydroxy nitrate moiety. This work greatly contributes to our understanding of ON and SOA formation from polyolefin monoterpene oxidation, which could be important in the northern continental US and the Midwest, where polyolefinic monoterpene emissions are greatest.

Management, regulation and environmental impacts of nitrogen fertilization in northwestern Europe under the Nitrates Directive

DEFF Research Database (Denmark)

van Grinsven, H.J.M.; ten Berge, H.F.M.; Dalgaard, Tommy

2012-01-01

Implementation of the Nitrates Directive (NiD) and its environmental impacts were compared for member states in the northwest of the European Union (Ireland, United Kingdom, Denmark, the Netherlands, Belgium, Northern France and Germany). The main sources of data were national reports for the third....... Issues of concern and improvement of the implementation of the NiD are accounting for the fertilizer value of nitrogen in manure, and relating application limits for total nitrogen (N) to potential crop yield and N removal. The most significant environmental effect of the implementation of the NiD since...... reports which can amount to more than 50 kgNha-1 yr-1. Differences between procedures in member states to assess nitrogen balances and water quality and a lack of cross-boundary policy evaluations are handicaps when benchmarking the effectiveness of the NiD. This provides a challenge for the European...

Nitrogen-nitrate exposure from drinking water and colorectal cancer risk for rural women in Wisconsin, USA.

Science.gov (United States)

McElroy, Jane A; Trentham-Dietz, Amy; Gangnon, Ronald E; Hampton, John M; Bersch, Andrew J; Kanarek, Marty S; Newcomb, Polly A

2008-09-01

One unintentional result of widespread adoption of nitrogen application to croplands over the past 50 years has been nitrate contamination of drinking water with few studies evaluating the risk of colorectal cancer. In our population-based case-control study of 475 women age 20-74 years with colorectal cancer and 1447 community controls living in rural Wisconsin, drinking water nitrate exposure were interpolated to subjects residences based on measurements which had been taken as part of a separate water quality survey in 1994. Individual level risk factor data was gathered in 1990-1992 and 1999-2001. Logistic regression models estimated the risk of colorectal cancer for the study period, separately and pooled. In the pooled analyses, an overall colorectal cancer risk was not observed for exposure to nitrate-nitrogen in the highest category (> or =10 ppm) compared to the lowest category (cancer cases in the highest compared to the lowest category. Statistically significant increased distal colon or rectal cancer risk was not observed. These results suggest that if an association exists with nitrate-nitrogen exposure from residential drinking water consumption, it may be limited to proximal colon cancer.

Nitrogen and oxygen isotopic constraints on the origin of atmospheric nitrate in coastal Antarctica

Directory of Open Access Journals (Sweden)

J. Savarino

2007-01-01

Full Text Available Throughout the year 2001, aerosol samples were collected continuously for 10 to 15 days at the French Antarctic Station Dumont d'Urville (DDU (66°40' S, l40°0' E, 40 m above mean sea level. The nitrogen and oxygen isotopic ratios of particulate nitrate at DDU exhibit seasonal variations that are among the most extreme observed for nitrate on Earth. In association with concentration measurements, the isotope ratios delineate four distinct periods, broadly consistent with previous studies on Antarctic coastal areas. During austral autumn and early winter (March to mid-July, nitrate concentrations attain a minimum between 10 and 30 ng m−3 (referred to as Period 2. Two local maxima in August (55 ng m−3 and November/December (165 ng m−3 are used to assign Period 3 (mid-July to September and Period 4 (October to December. Period 1 (January to March is a transition period between the maximum concentration of Period 4 and the background concentration of Period 2. These seasonal changes are reflected in changes of the nitrogen and oxygen isotope ratios. During Period 2, which is characterized by background concentrations, the isotope ratios are in the range of previous measurements at mid-latitudes: δ18Ovsmow=(77.2±8.6‰; Δ17O=(29.8±4.4‰; δ15Nair=(−4.4±5.4‰ (mean ± one standard deviation. Period 3 is accompanied by a significant increase of the oxygen isotope ratios and a small increase of the nitrogen isotope ratio to δ18Ovsmow=(98.8±13.9‰; Δ17O=(38.8±4.7‰ and δ15Nair=(4.3±8.20‰. Period 4 is characterized by a minimum 15N/14N ratio, only matched by one prior study of Antarctic aerosols, and oxygen isotope ratios similar to Period 2: δ18Ovsmow=(77.2±7.7‰; Δ17O=(31.1±3.2‰; δ15Nair=(−32.7±8.4‰. Finally, during Period 1, isotope ratios reach minimum values for oxygen and intermediate values for nitrogen: δ18Ovsmow=63.2±2.5‰; Δ17O=24.0±1.1‰; δ15Nair=−17.9±4.0‰. Based on the measured

Stimulation effect of synthetic cytokinins on the uptake and incorporation of nitrogen-15-labelled ammonium nitrate and urea in wheat leaves

International Nuclear Information System (INIS)

Iglewski, S.M.; Szarvas, T.; Pozsar, B.I.

1977-01-01

The turnover of different labelled nitrogen sources in wheat leaves has been investigated using the isotopic tracer technique. The 15 N at.% was determined in free ammonium ion, in the nitrate and the nitrite levels, and also in the non-disintegrated urea. The accumulation and the incorporation of stable nitrogen was measured in the TCA insoluble protein fraction. According to the experimental data the intensity of incorporation of urea nitrogen is relatively higher than that of the different inorganic compounds. The utilization of ammonium ion was 76% compared with the urea, whereas that of the nitrate nitrogen was 60% in the wheat leaves. The incorporation rate of the two nitrogen atoms from ammonium nitrate was 32% lower than that of the urea nitrogen, in the leaf protein of Bezostaia-1 wheat variety. The turnover of urea through the transamination was very rapid, the amination with ammonium ion was slower, and the first phase of the nitrate reduction was relatively more retarded than the nitrite reduction. The endogenous cytokinin-like biological activity and some synthetic cytokinins (kinetin, benzyladenine) have a remarkably stimulating effect on the incorporation of the different 15 N-labelled nitrogen sources into the leaf protein fraction. (author)

Total salivary nitrates and nitrites in oral health and periodontal disease.

Science.gov (United States)

Sánchez, Gabriel A; Miozza, Valeria A; Delgado, Alejandra; Busch, Lucila

2014-01-30

It is well known that nitrites are increased in saliva from patients with periodontal disease. In the oral cavity, nitrites may derive partly from the reduction of nitrates by oral bacteria. Nitrates have been reported as a defence-related mechanism. Thus, the aim of the present study was to determine the salivary levels of total nitrate and nitrite and their relationship, in unstimulated and stimulated saliva from periodontal healthy subjects, and from patients with chronic periodontal disease. Nitrates and nitrites were determined in saliva from thirty healthy subjects and forty-four patients with periodontal disease. A significant increase in salivary nitrates and nitrites was observed. Nitrates and nitrites concentration was related to clinical attachment level (CAL). A positive and significant Pearson's correlation was found between salivary total nitrates and nitrites. Periodontal treatment induced clinical improvement and decreased nitrates and nitrites. It is concluded that salivary nitrates and nitrites increase, in patients with periodontal disease, could be related to defence mechanisms. The possibility that the salivary glands respond to oral infectious diseases by increasing nitrate secretion should be explored further. Copyright © 2013 Elsevier Inc. All rights reserved.

Enhanced microalgal lipid production with media engineering of potassium nitrate as a nitrogen source.

Science.gov (United States)

Gour, Rakesh Singh; Bairagi, Madhusudan; Garlapati, Vijay Kumar; Kant, Anil

2018-01-01

Algal biofuels are far from a commercial reality due to the technical challenges associated with their growth and lipid extraction procedures. In this study, we investigated the effect of 4 different media and 5 different nitrogen sources at 5 levels on the growth, biomass and lipid productivity of Scenedesmus sp and Chlorella sp The hypothesis was that a nitrogen source can be identified that provides enough stress to accumulate lipids without compromising significantly on biomass and lipid productivity. A maximum specific growth rate and doubling per day have been observed with algal species using modified BG-11 medium. Among the tested nitrogen sources, 2.5 mM potassium nitrate as a nitrogen constituent of modified BG-11 medium resulted in higher lipid content and productivity in the case of S. dimorphus (29.15%, 15.449 mg L -1 day -1 ). Another noteworthy outcome of the present study lies in the usage of a smaller amount of the nitrogen source, i.e., 2.5 mM, which is found to be 7 times less than the standard BG11 media (17.60 mM sodium nitrate).

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

Science.gov (United States)

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

Effect of nitrogen nutrition on growth and nitrate accumulation in lettuce (Lactuca sativa L.), under various conditions of radiation and temperature

International Nuclear Information System (INIS)

Dapoigny, L.; Tourdonnet, S. de; Roger-Estrade, G.; Jeuffroy, M.H.; Fleury, A.

2000-01-01

A better understanding of the effect of environmental factors on growth and nitrate accumulation in plants is necessary to develop cultivation practices, and in particular for providing lettuces with a low nitrate content. This study was conducted to analyse the effect of nitrogen supply on the interception and conversion of the PAR in dry matter, and on the nitrate and water accumulations in fresh tissues of the lettuce, for various conditions of temperature and radiation. The growth, and water and nitrate concentrations of two soilless cultures of lettuce (summer and autumn) were measured for two levels of radiation and two levels of nitrogen supply. RUE ranged from 2.12 to 3.50 gMJ -1 , being higher for a low radiation level and for a high nitrogen supply. There was a positive correlation between the lettuce nitrate and water contents. The slope of this relationship was not affected by environmental conditions, indicating a strong interdependance between nitrate and water accumulation in lettuce. (author) [fr

Physical Factors Correlate to Microbial Community Structure and Nitrogen Cycling Gene Abundance in a Nitrate Fed Eutrophic Lagoon.

Science.gov (United States)

Highton, Matthew P; Roosa, Stéphanie; Crawshaw, Josie; Schallenberg, Marc; Morales, Sergio E

2016-01-01

Nitrogenous run-off from farmed pastures contributes to the eutrophication of Lake Ellesmere, a large shallow lagoon/lake on the east coast of New Zealand. Tributaries periodically deliver high loads of nitrate to the lake which likely affect microbial communities therein. We hypothesized that a nutrient gradient would form from the potential sources (tributaries) creating a disturbance resulting in changes in microbial community structure. To test this we first determined the existence of such a gradient but found only a weak nitrogen (TN) and phosphorous gradient (DRP). Changes in microbial communities were determined by measuring functional potential (quantification of nitrogen cycling genes via nifH , nirS , nosZI , and nosZII using qPCR), potential activity (via denitrification enzyme activity), as well as using changes in total community (via 16S rRNA gene amplicon sequencing). Our results demonstrated that changes in microbial communities at a phylogenetic (relative abundance) and functional level (proportion of the microbial community carrying nifH and nosZI genes) were most strongly associated with physical gradients (e.g., lake depth, sediment grain size, sediment porosity) and not nutrient concentrations. Low nitrate influx at the time of sampling is proposed as a factor contributing to the observed patterns.

Physical factors correlate to microbial community structure and nitrogen cycling gene abundance in a nitrate fed eutrophic lagoon

Directory of Open Access Journals (Sweden)

Matthew Paul Highton

2016-10-01

Full Text Available Nitrogenous run-off from farmed pastures contributes to the eutrophication of Lake Ellesmere, a large shallow lagoon/lake on the east coast of New Zealand. Tributaries periodically deliver high loads of nitrate to the lake which likely affect microbial communities therein. We hypothesized that a nutrient gradient would form from the potential sources (tributaries creating a disturbance resulting in changes in microbial community structure. To test this we first determined the existence of such a gradient but found only a weak nitrogen (TN and phosphorous gradient (DRP. Changes in microbial communities were determined by measuring functional potential (quantification of nitrogen cycling genes via nifH, nirS, nosZI and nosZII using qPCR, potential activity (via denitrification enzyme activity, as well as using changes in total community (via 16S rRNA gene amplicon sequencing. Our results demonstrated that changes in microbial communities at a phylogenetic (relative abundance and functional level (proportion of the microbial community carrying nifH and nosZI genes were most strongly associated with physical gradients (e.g. lake depth, sediment grain size, sediment porosity and not nutrient concentrations. Low nitrate influx at the time of sampling is proposed as a factor contributing to the observed patterns.

Distribution of nitrogen-13 from labeled nitrate (13NO3-) in humans and rats

International Nuclear Information System (INIS)

Witter, J.P.; Gatley, S.J.; Balish, E.

1979-01-01

The body distribution of gavaged or intravenously administered nitrate labeled with nitrogen-13 was studied in humans and rats with the following results: (1) the labeled compound is not quickly absorbed from the stomach; (2) the concentration of the label increases inside the lower intestinal tract (cecum and large intestine) when ingested or intravenously injected; and (3) humans and rats have the capacity to store a portion of the label in their bodies. These observations indicate that depletion of body stores, the passage of nitrate down the gut, or the secretion of nitrate into the intestinal lumen may be a better explanation of the urinary, ileal, and fecal concentrations of nitrate and nitrate recently measured in humans than a bacterial nitrification reaction in the intestines, as suggested by Tannenbaum, et al

Nitrate leaching from short-hydroperiod floodplain soils

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B. Huber

2012-11-01

Full Text Available Numerous studies have shown the importance of riparian zones to reduce nitrate (NO₃⁻ contamination coming from adjacent agricultural land. Much less is known about nitrogen (N transformations and nitrate fluxes in riparian soils with short hydroperiods (1–3 days of inundation and there is no study that could show whether these soils are a N sink or source. Within a restored section of the Thur River in NE Switzerland, we measured nitrate concentrations in soil solutions as an indicator of the net nitrate production. Samples were collected along a quasi-successional gradient from frequently inundated gravel bars to an alluvial forest, at three different depths (10, 50 and 100 cm over a one-year period. Along this gradient we quantified N input (atmospheric deposition and sedimentation and N output (leaching to create a nitrogen balance and assess the risk of nitrate leaching from the unsaturated soil to the groundwater. Overall, the main factor explaining the differences in nitrate concentrations was the field capacity (FC. In subsoils with high FCs and VWC near FC, high nitrate concentrations were observed, often exceeding the Swiss and EU groundwater quality criterions of 400 and 800 μmol L⁻¹, respectively. High sedimentation rates of river-derived nitrogen led to apparent N retention up to 200 kg N ha⁻¹ yr⁻¹ in the frequently inundated zones. By contrast, in the mature alluvial forest, nitrate leaching exceeded total N input most of the time. As a result of the large soil N pools, high amounts of nitrate were produced by nitrification and up to 94 kg N-NO₃⁻ ha⁻¹ yr⁻¹ were leached into the groundwater. Thus, during flooding when water fluxes are high, nitrate from soils can contribute up to 11% to the total nitrate load in groundwater.

Enhanced nitrogen selectivity for nitrate reduction on Cu–nZVI by TiO{sub 2} photocatalysts under UV irradiation

Energy Technology Data Exchange (ETDEWEB)

Krasae, Nalinee, E-mail: k_nalinee@kkumail.com [Department of Chemical Engineering, Faculty of Engineering, Khon Kaen University, Khon Kaen 40002 (Thailand); Chemical Kinetics and Applied Catalysis Laboratory (CKCL), Faculty of Engineering, Khon Kaen University, Khon Kaen 40002 (Thailand); Wantala, Kitirote, E-mail: kitirote@kku.ac.th [Department of Chemical Engineering, Faculty of Engineering, Khon Kaen University, Khon Kaen 40002 (Thailand); Chemical Kinetics and Applied Catalysis Laboratory (CKCL), Faculty of Engineering, Khon Kaen University, Khon Kaen 40002 (Thailand); Research Center for Environmental and Hazardous Substance Management (EHSM), Faculty of Engineering, Khon Kaen University, Khon Kaen 40002 (Thailand)

2016-09-01

Highlights: • Photocatalytic process has been enhancing the nitrate removal over Cu–nZVI/TiO{sub 2}. • Highly nitrogen selectivity more than 80% over Cu–nZVI/TiO{sub 2}. • Nitrate removal can be reacted in neutral pH of solutions. - Abstract: The aims of this work were to study the effect of Cu–nZVI with and without TiO{sub 2} 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/TiO{sub 2} such as specific surface area, crystalline phase, oxidation state of Cu and Fe and morphology were determined by N{sub 2} 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 TiO{sub 2}, 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/TiO{sub 2} was found to be about 4 and 36 m{sup 2}/g, respectively. The XRD pattern of Fe{sup 0} in Cu–nZVI was found at 45° (2θ), whereas Cu–nZVI/TiO{sub 2} cannot be observed. TEM images can confirm the position of the core and the shell of nZVI for Fe{sup 0} and ferric oxide. Cu–nZVI/TiO{sub 2} proved to have higher activity in nitrogen reduction performance than that without TiO{sub 2} 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/TiO{sub 2} greater than 82% was found at an initial solution pH of 4 and 7. The main effects of Cu–nZVI with and without TiO{sub 2} and the initial nitrate concentration on nitrate

[Effects of nitrogen application level on soil nitrate accumulation and ammonia volatilization in high-yielding wheat field].

Science.gov (United States)

Wang, Dong; Yu, Zhenwen; Yu, Wenming; Shi, Yu; Zhou, Zhongxin

2006-09-01

The study showed that during the period from sowing to pre-wintering, the soil nitrate in high-yielding wheat field moved down to deeper layers, and accumulated in the layers below 140 cm. An application rate of 96-168 kg N x hm(-2) increased the nitrate content in 0-60 cm soil layer and the wheat grain yield and its protein content, and decreased the proportion of apparent N loss to applied N and the ammonia volatilization loss from basal nitrogen. Applying 240 kg N x hm(-2) promoted the downward movement of soil nitrate and its accumulation in deeper layers, increased the proportion of apparent N loss to applied N and the ammonia volatilization loss from basal nitrogen, had no significant effect on the protein content of wheat grain, but decreased the grain yield. The appropriate application rate of nitrogen on high-yielding wheat field was 132-204 kg N x hm(-2).

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

Science.gov (United States)

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

The distribution and utilization of nitrogen in developing zea mays L. seedlings

International Nuclear Information System (INIS)

Watt, M.P.M. de O.C.

1987-01-01

During the first five days of germination, in the presence of NO - 3 - 15 N and N-SERVE, the nitrogen reserves of Zea mays L. caryopses accounted for 75% of the total nitrogen content of the seedlings. By day 7, exogenous nitrate contributed to all the inorganic nitrogen measured in the plant. Although NO - 3 - 15 N (94,2 atom % 15 N) was supplied throughout the germination process, and increasing pool of unlabelled nitrate was detected in both the grain and the seedling during this period. It appears that during germination in maize there is an oxidative pathway from reduced nitrogen in the reserve proteins to nitrate-nitrogen which is then supplied to the developing embryo. The levels of nitrate in the leaf increased towards the sheath, whereas other forms of nitrogen, nitrate reductase activity and capacity for nitrate accumulation increased in the opposite direction. Studies with mesophyll and bundle sheath protoplasts showed that the mesophyll tissue contributes over 80% of the total leaf content of inorganic nitrogen. Leaf tissue of Zea mays was found to have the capacity to assimilate nitrate in the dark, but at a lower rate than in the light. Oxygen did not restrict the initial rate of nitrate reduction in the dark. The rate of the in vivo nitrate reduction declined during the second hour of dark anaerobiosis, and was only restored upon supply of oxygen. Under dark anaerobic conditions nitrite accumulated and, on transfer to oxygen, the accumulate nitrite was reduced

Nitration of benzo[a]pyrene adsorbed on coal fly ash particles by nitrogen dioxide: role of thermal activation.

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Kristovich, Robert L; Dutta, Prabir K

2005-09-15

Nitration of benzo[a]pyrene (BaP) by nitrogen dioxide (NO2) adsorbed on the surface of thermally activated coal fly ash and model aluminosilicate particles led to the formation of nitrobenzo[a]pyrenes as verified by extraction and gas chromatography/mass spectrometry (GC/MS). In situ diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS) was utilized to follow the nitration reaction on the surface of zeolite Y. Nitrobenzo[a]pyrene formation was observed along with the formation of nitrous acid and nitrate species. The formation of the BaP radical cation was also observed on thermally activated aluminosilicate particles by electron spin resonance (ESR) spectroscopy. On the basis of GC/MS, DRIFTS, and ESR spectroscopy results, a mechanism of nitration involving intermediate BaP radical cations generated on thermally activated aluminosilicate particles is proposed. These observations have led to the hypothesis that nitration of adsorbed polyaromatic hydrocarbons on coal fly ash by reaction with nitrogen oxides can occur in the smokestack, but with the aging of the fly ash particles, the extent of the nitration reaction will be diminished.

Nitrogen Starvation Acclimation in Synechococcus elongatus: Redox-Control and the Role of Nitrate Reduction as an Electron Sink

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Alexander Klotz

2015-03-01

Full Text Available Nitrogen starvation acclimation in non-diazotrophic cyanobacteria is characterized by a process termed chlorosis, where the light harvesting pigments are degraded and the cells gradually tune down photosynthetic and metabolic activities. The chlorosis response is governed by a complex and poorly understood regulatory network, which converges at the expression of the nblA gene, the triggering factor for phycobiliprotein degradation. This study established a method that allows uncoupling metabolic and redox-signals involved in nitrogen-starvation acclimation. Inhibition of glutamine synthetase (GS by a precise dosage of l-methionine-sulfoximine (MSX mimics the metabolic situation of nitrogen starvation. Addition of nitrate to such MSX-inhibited cells eliminates the associated redox-stress by enabling electron flow towards nitrate/nitrite reduction and thereby, prevents the induction of nblA expression and the associated chlorosis response. This study demonstrates that nitrogen starvation is perceived not only through metabolic signals, but requires a redox signal indicating over-reduction of PSI-reduced electron acceptors. It further establishes a cryptic role of nitrate/nitrite reductases as electron sinks to balance conditions of over-reduction.

Nitrogen Starvation Acclimation in Synechococcus elongatus: Redox-Control and the Role of Nitrate Reduction as an Electron Sink

Science.gov (United States)

Klotz, Alexander; Reinhold, Edgar; Doello, Sofía; Forchhammer, Karl

2015-01-01

Nitrogen starvation acclimation in non-diazotrophic cyanobacteria is characterized by a process termed chlorosis, where the light harvesting pigments are degraded and the cells gradually tune down photosynthetic and metabolic activities. The chlorosis response is governed by a complex and poorly understood regulatory network, which converges at the expression of the nblA gene, the triggering factor for phycobiliprotein degradation. This study established a method that allows uncoupling metabolic and redox-signals involved in nitrogen-starvation acclimation. Inhibition of glutamine synthetase (GS) by a precise dosage of l-methionine-sulfoximine (MSX) mimics the metabolic situation of nitrogen starvation. Addition of nitrate to such MSX-inhibited cells eliminates the associated redox-stress by enabling electron flow towards nitrate/nitrite reduction and thereby, prevents the induction of nblA expression and the associated chlorosis response. This study demonstrates that nitrogen starvation is perceived not only through metabolic signals, but requires a redox signal indicating over-reduction of PSI-reduced electron acceptors. It further establishes a cryptic role of nitrate/nitrite reductases as electron sinks to balance conditions of over-reduction. PMID:25780959

Nitrogen-isotopes and multi-parameter sewage water test for identification of nitrate sources: Groundwater body Marchfeld East of Vienna

Science.gov (United States)

Kralik, Martin

2017-04-01

The application of nitrogen and oxygen isotopes in nitrate allows, under favourable circumstances, to identify potential sources such as precipitation, chemical fertilisers and manure or sewage water. Without any additional tracer, the source distinction of nitrate from manure or sewage water is still difficult. Even the application of boron isotopes can in some cases not avoid ambiguous interpretation. Therefore, the Environment Agency Austria developed a new multi parametrical indicator test to allow the identification and quantification of pollution by domestic sewage water. The test analyses 8 substances well known to occur in sewage water: Acesulfame and sucralose (two artificial, calorie-free sweeteners), benzotriazole and tolyltriazole (two industrial chemicals/corrosion inhibitors), metoprolol, sotalol, carbamazepine and the metabolite 10,11-Dihydro-10,11-dihydroxycarbamazepine (pharmaceuticals) [1]. These substances are polar and degradation in the aquatic system by microbiological processes is not documented. These 8 Substances do not occur naturally which make them ideal tracers. The test can detect wastewater in the analysed water sample down to 0.1 %. This ideal coupling of these analytic tests helps to identify the nitrogen sources in the groundwater body Marchfeld East of Vienna to a high confidence level. In addition, the results allow a reasonable quantification of nitrogen sources from different types of fertilizers as well as sewage water contributions close to villages and in wells recharged by bank filtration. Recent investigations of groundwater in selected wells in Marchfeld [2] indicated a clear nitrogen contribution by wastewater leakages (sewers or septic tanks) to the total nitrogen budget. However, this contribution is shrinking and the main source comes still from agricultural activities. [1] Humer, F.; Weiss, S.; Reinnicke, S.; Clara, M.; Grath, J.; Windhofer, G. (2013): Multi parametrical indicator test for urban wastewater influence

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

Science.gov (United States)

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

2017-12-19

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

Bioelectrode-based approach for enhancing nitrate and nitrite removal and electricity generation from eutrophic lakes

DEFF Research Database (Denmark)

Zhang, Yifeng; Angelidaki, Irini

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...... 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...

Nitrate pollution of groundwater

International Nuclear Information System (INIS)

Heaton, T.H.E.

1986-01-01

Concern about the possible health risks associated with the consumption of nitrate has led many countries, including South Africa, to propose that 10mg of nitrogen (as nitrate or nitrite) per liter should be the maximum allowable limit for domestic water supplies. Groundwater in certain parts of South Africa and Namibia contains nitrate in concentrations which exceed this limit. The CSIR's Natural Isotope Division has been studying the nitrogen isotope composition of the nitrate as an aid to investigation into the sources of this nitrate contamination

The production of cyanobacterial carbon under nitrogen-limited cultivation and its potential for nitrate removal.

Science.gov (United States)

Huang, Yingying; Li, Panpan; Chen, Guiqin; Peng, Lin; Chen, Xuechu

2018-01-01

Harmful cyanobacterial blooms (CyanoHABs) represent a serious threat to aquatic ecosystems. A beneficial use for these harmful microorganisms would be a promising resolution of this urgent issue. This study applied a simple method, nitrogen limitation, to cultivate cyanobacteria aimed at producing cyanobacterial carbon for denitrification. Under nitrogen-limited conditions, the common cyanobacterium, Microcystis, efficiently used nitrate, and had a higher intracellular C/N ratio. More importantly, organic carbons easily leached from its dry powder; these leachates were biodegradable and contained a larger amount of dissolved organic carbon (DOC) and carbohydrates, but a smaller amount of dissolved total nitrogen (DTN) and proteins. When applied to an anoxic system with a sediment-water interface, a significant increase of the specific NO X - -N removal rate was observed that was 14.2 times greater than that of the control. This study first suggests that nitrogen-limited cultivation is an efficient way to induce organic and carbohydrate accumulation in cyanobacteria, as well as a high C/N ratio, and that these cyanobacteria can act as a promising carbon source for denitrification. The results indicate that application as a carbon source is not only a new way to utilize cyanobacteria, but it also contributes to nitrogen removal in aquatic ecosystems, further limiting the proliferation of CyanoHABs. Copyright © 2017. Published by Elsevier Ltd.

Assimilation of ammonium and nitrate nitrogen by bean plants

International Nuclear Information System (INIS)

Volk, R.J.; Chaillou, S.; Morot-Gaudry, J.F.; Mariotti, A.

1989-01-01

Enhanced growth is often observed in plants growing on combined ammonium and nitrate nutrition. The physiological basis for such enhancement was examined by exposing non-nodulated bean (Phaseolus vulgaris L.) plants to 15 N-labeled, 1.0 mM N solutions containing 0, 33, 67 or 100% of the N as ammonium, the balance being nitrate. Maximal total N uptake and biomass production were attained by plants receiving 33% ammonium. A higher proportion of incoming ammonium than nitrate was incorporated into root protein. This was accompanied by increased partitioning of plant biomass to roots. It was concluded that as a consequence of greater N metabolism in the root under mixed ammonium and nitrate nutrition, the root became a more active sink for photosynthate. Concurrently, the augmented supply of N to the shoot enhanced net photosynthesis as reflected in increased plant biomass

Mineral, protein and nitrate contents in leaves of Pereskia aculeata subjected to nitrogen fertilization

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Maria Regina de Miranda Souza

2016-03-01

Full Text Available Considering that nitrogen is directly related to leaf protein content, the nitrogen fertilization in Pereskia aculeata plants may affect the protein content and increase its nutritional potential. This study aimed at assessing the effect of nitrogen fertilization on mineral, protein and nitrate contents, as well as the yield of P. aculeata leaves. A randomized blocks design was used, with three replications and five treatments, consisting of increasing topdressing nitrogen doses (0-400 kg ha-1, in soil with organic matter content of 4.0 dag kg-1. Three harvests were performed for leaf analysis. No significant effect was observed for mineral and protein content or leaf fresh mass yield. The mean values for mineral composition were: 3.52 dag kg-1 of N, 0.47 dag kg-1 of P, 4.65 dag kg-1 of Ca, 0.71 dag kg-1 of Mg, 0.25 dag kg-1 of S, 36.64 mg kg-1 of Zn and 174.13 mg kg-1 of Fe. The mean content for protein was 21.86 % and the leaf fresh mass yield was 0.971 kg plant-1. K levels decreased from 50 kg ha-1 of N. Nitrate increased linearly with the nitrogen fertilization, reaching a maximum value of 78.2 mg kg-1 of fresh mass, well below the health risk threshold. It was concluded that a soil with high organic matter content does not require nitrogen fertilization. However, doses up to 400 kg ha-1 of nitrogen ensure adequate leaf yield and protein and mineral contents within the desired range for the species, being a food rich in proteins, iron and calcium.

Investigation on the Assimilation of Nitrogen by Maize Roots and the Transport of Some Major Nitrogen Compounds by Xylem Sap

DEFF Research Database (Denmark)

Ivanko, S.; Ingversen, J.

1971-01-01

The uptake and assimilation of nitrate and ammonia have been studied in Zea mays. Nitrogen-starved maize roots are capable of accumulating a potential capacity for nitrogen uptake and assimilation. Reestablishment of nitrogen supply leads to intense uptake, reaching 154 % of the reference variant...... level after 24 hours when nitrate is supplied, and 121 % when ammonia is supplied. After 24 hours the insoluble nitrogen fraction accounts for 80, 54 and 55 % of the total taken up in the PK + NO3-, PK + NH4+ and NPK variants respectively....

Over-expression of a tobacco nitrate reductase gene in wheat (Triticum aestivum L.) increases seed protein content and weight without augmenting nitrogen supplying.

Science.gov (United States)

Zhao, Xiao-Qiang; Nie, Xuan-Li; Xiao, Xing-Guo

2013-01-01

Heavy nitrogen (N) application to gain higher yield of wheat (Triticum aestivum L.) resulted in increased production cost and environment pollution. How to diminish the N supply without losing yield and/or quality remains a challenge. To meet the challenge, we integrated and expressed a tobacco nitrate reductase gene (NR) in transgenic wheat. The 35S-NR gene was transferred into two winter cultivars, "Nongda146" and "Jimai6358", by Agrobacterium-mediation. Over-expression of the transgene remarkably enhanced T1 foliar NR activity and significantly augmented T2 seed protein content and 1000-grain weight in 63.8% and 68.1% of T1 offspring (total 67 individuals analyzed), respectively. Our results suggest that constitutive expression of foreign nitrate reductase gene(s) in wheat might improve nitrogen use efficiency and thus make it possible to increase seed protein content and weight without augmenting N supplying.

Over-expression of a tobacco nitrate reductase gene in wheat (Triticum aestivum L. increases seed protein content and weight without augmenting nitrogen supplying.

Directory of Open Access Journals (Sweden)

Xiao-Qiang Zhao

Full Text Available Heavy nitrogen (N application to gain higher yield of wheat (Triticum aestivum L. resulted in increased production cost and environment pollution. How to diminish the N supply without losing yield and/or quality remains a challenge. To meet the challenge, we integrated and expressed a tobacco nitrate reductase gene (NR in transgenic wheat. The 35S-NR gene was transferred into two winter cultivars, "Nongda146" and "Jimai6358", by Agrobacterium-mediation. Over-expression of the transgene remarkably enhanced T1 foliar NR activity and significantly augmented T2 seed protein content and 1000-grain weight in 63.8% and 68.1% of T1 offspring (total 67 individuals analyzed, respectively. Our results suggest that constitutive expression of foreign nitrate reductase gene(s in wheat might improve nitrogen use efficiency and thus make it possible to increase seed protein content and weight without augmenting N supplying.

A seasonal nitrogen deposition budget for Rocky Mountain National Park.

Science.gov (United States)

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

2013-07-01

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

Nitrate and ammonium lead to distinct global dynamic phosphorylation patterns when resupplied to nitrogen-starved Arabidopsis seedlings.

Science.gov (United States)

Engelsberger, Wolfgang R; Schulze, Waltraud X

2012-03-01

Nitrogen is an essential macronutrient for plant growth and development. Inorganic nitrogen and its assimilation products control various metabolic, physiological and developmental processes. Although the transcriptional responses induced by nitrogen have been extensively studied in the past, our work here focused on the discovery of candidate proteins for regulatory events that are complementary to transcriptional changes. Most signaling pathways involve modulation of protein abundance and/or activity by protein phosphorylation. Therefore, we analyzed the dynamic changes in protein phosphorylation in membrane and soluble proteins from plants exposed to rapid changes in nutrient availability over a time course of 30 min. Plants were starved of nitrogen and subsequently resupplied with nitrogen in the form of nitrate or ammonium. Proteins with maximum change in their phosphorylation level at up to 5 min after nitrogen resupply (fast responses) included GPI-anchored proteins, receptor kinases and transcription factors, while proteins with maximum change in their phosphorylation level after 10 min of nitrogen resupply (late responses) included proteins involved in protein synthesis and degradation, as well as proteins with functions in central metabolism and hormone metabolism. Resupply of nitrogen in the form of nitrate or ammonium resulted in distinct phosphorylation patterns, mainly of proteins with signaling functions, transcription factors and transporters. © 2011 The Authors. The Plant Journal © 2011 Blackwell Publishing Ltd.

Cloning and nitrate induction of nitrate reductase mRNA

OpenAIRE

Cheng, Chi-Lien; Dewdney, Julia; Kleinhofs, Andris; Goodman, Howard M.

1986-01-01

Nitrate is the major source of nitrogen taken from the soil by higher plants but requires reduction to ammonia prior to incorporation into amino acids. The first enzyme in the reducing pathway is a nitrate-inducible enzyme, nitrate reductase (EC 1.6.6.1). A specific polyclonal antiserum raised against purified barley nitrate reductase has been used to immunoprecipitate in vivo labeled protein and in vitro translation products, demonstrating that nitrate induction increases nitrate reductase p...

Effects of inorganic nitrogen sources on the production of PP-V [(10Z)-12-carboxyl-monascorubramine] and the Expression of the nitrate assimilation gene cluster by Penicillium sp. AZ.

Science.gov (United States)

Arai, Teppei; Umemura, Sara; Ota, Tamaki; Ogihara, Jun; Kato, Jun; Kasumi, Takafumi

2012-01-01

A fungal strain, Penicillium sp. AZ, produced the azaphilone Monascus pigment homolog when cultured in a medium composed of soluble starch, ammonium nitrate, yeast extract, and citrate buffer, pH 5.0. One of the typical features of violet pigment PP-V [(10Z)-12-carboxyl-monascorubramine] is that pyranoid oxygen is replaced with nitrogen. In this study, we found that ammonia and nitrate nitrogen are available for PP-V biosynthesis, and that ammonia nitrogen was much more effective than nitrate nitrogen. Further, we isolated nitrate assimilation gene cluster, niaD, niiA, and crnA, and analyzed the expression of these genes. The expression levels of all these genes increased with sodium nitrate addition to the culture medium. The results obtained here strongly suggest that Penicillium sp. AZ produced PP-V using nitrate in the form of ammonium reduced from nitrate through a bioprocess assimilatory reaction.

Azospirillum Inoculation Alters Nitrate Reductase Activity and Nitrogen Uptake in Wheat Plant Under Water Deficit Conditions

OpenAIRE

N. Aliasgharzad, N. Aliasgharzad; Heydaryan, Zahra; Sarikhani, M.R

2014-01-01

Water deficit stress usually diminishes nitrogen uptake by plants. There are evidences that some nitrogen fixing bacteria can alleviate this stress by supplying nitrogen and improving its metabolism in plants. Four Azospirillum strains, A. lipoferum AC45-II, A. brasilense AC46-I, A. irakense AC49-VII and A. irakense AC51-VI were tested for nitrate reductase activity (NRA). In a pot culture experiment using a sandy loam soil, wheat plants (Triticum aestivum L. cv. Sardari) were inoculated with...

Nitrogen-isotope ratio studies of soils and groundwater nitrate from alluvial fan aquifers in Texas

International Nuclear Information System (INIS)

Kreitler, C.W.

1979-01-01

Kreitler has previously identified two ranges of nitrogen-isotope values (delta 15 N) for soil nitrate under different land uses in west Texas: nitrate originating from nonfertilized, cultivated fields (delta 14 N range, 2 to +8per thousand with an average of +4.9per thousand), and nitrate from animal wastes (delta 15 N range, +10 to +22per thousand with an average of +14.4per thousand). The delta 15 N of groundwater nitrate from irrigation wells on the Lockhart and Taylor and alluvial fans range from +3.3 to +10.8per thousand with an average of +7.3per thousand. Ground water from domestic wells on the two fans has higher nitrate concentrations and a more positive delta 15 N range (+6.7 to 18.2per thousand with an average of +11.1per thousand) than wells located in the cultivated fields. Nitrate contamination of wells located in cultivated fields results primarily from cultivation with ammonium-type fertilizers, whereas animal wastes are contaminating domestic well waters. (Auth.)

Evaluating Nitrogen Management Options for Reducing Nitrate Leaching from Northeast U.S. Pastures

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William L. Stout

2001-01-01

Full Text Available Substantial amounts of nitrate nitrogen NO3-N can leach from intensively grazed pasture in the northeast U.S. where there is about 30 cm of groundwater recharge, annually. Management options for reducing NO3-N leaching were evaluated for this environment using the Cornell Net Carbohydrate and Protein System Model and a recently developed nitrogen leaching index. Management options utilizing energy supplementation of grazing dairy cows could improve nitrogen efficiency within the cow, but would not necessarily reduce NO3-N leaching at the pasture scale if stocking rate was not controlled. The management option of using white clover to supply nitrogen to the pasture decreased NO3-N leaching, but produced less dry matter yield, which in turn reduced stocking rate. The economic returns of reducing NO3-N with these options need to be evaluated in light of milk prices and commodity and fertilizer nitrogen costs. At current prices and costs, the economic benefit from the energy supplementation options is substantial.

Effects of substrate type on plant growth and nitrogen and nitrate concentration in spinach

Science.gov (United States)

The effects of three commercial substrates (a mixture of forest residues, composted grape husks, and white peat; black peat; and coir) on plant growth and nitrogen (N) and nitrate (NO3) concentration and content were evaluated in spinach (Spinacia oleracea L. cv. Tapir). Spinach seedlings were trans...

PENETRATION OF NITROGEN INTO WATER AS A RESULT OF FERTILIZATION OF LIGHT SOIL

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Franciszek Czyżyk

2014-10-01

Full Text Available In this article there are present the results of six-year study of infiltration of nitrogen through the sand soil (loamy sand. Every year the soil was fertilized by compost (from sewage sludge and equivalent doses of nitrogen in mineral fertilizers. Two variants of compost fertilization (K1-10 and K2-15 g N·m-2 were used. Additionally two variants of NPK with equivalent doses of nitrogen as an ammonium nitrate supplemented with PK as a superphosphate and potassium salt were applied. Systematically there were investigated the volume of all leachates and their chemical composition. With increasing doses of fertilizers the concentrations of total nitrogen and nitrate nitrogen in the leachate were increased. The concentration of nitrogen in the leachate from the soil fertilized by nitrate was much greater than in compost with equivalent dose of nitrogen. Not only nitrates but also nitrogen from soluble organic compounds were rinsed from the soil. In the case of soil fertilized by compost the participation of nitrates in the total value of nitorgen in the leachate was 41-77%. However in the case of fertilization by ammonium sulphate this proportion was significantly higher and was in the range 60-95%. Over the years, a systematic soil fertilization by both ways increased the nitrogen concentrations in leachate. It shows that in the soil there is surplus of nitrogen, increasing during the time.

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

Science.gov (United States)

Klement, Laura; Bach, Martin; Breuer, Lutz

2016-04-01

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.

Nitrate leaching in a winter wheat-summer maize rotation on a calcareous soil as affected by nitrogen and straw management.

Science.gov (United States)

Huang, Tao; Ju, Xiaotang; Yang, Hao

2017-02-08

Nitrate leaching is one of the most important pathways of nitrogen (N) loss which leads to groundwater contamination or surface water eutrophication. Clarifying the rates, controlling factors and characteristics of nitrate leaching is the pre-requisite for proposing effective mitigation strategies. We investigated the effects of interactions among chemical N fertilizer, straw and manure applications on nitrogen leaching in an intensively managed calcareous Fluvo-aquic soil with winter wheat-summer maize cropping rotations on the North China Plain from October 2010 to September 2013 using ceramic suction cups and seepage water calculations based on a long-term field experiment. Annual nitrate leaching reached 38-60 kg N ha -1 from conventional N managements, but declined by 32-71% due to optimum N, compost manure or municipal waste treatments, respectively. Nitrate leaching concentrated in the summer maize season, and fewer leaching events with high amounts are the characteristics of nitrate leaching in this region. Overuse of chemical N fertilizers, high net mineralization and nitrification, together with predominance of rainfall in the summer season with light soil texture are the main controlling factors responsible for the high nitrate leaching loss in this soil-crop-climatic system.

Analytical developments in the measurements of boron, nitrate, phosphate and sulphate isotopes and case examples of discrimination of nitrogen and sulphur sources in pollution studies

International Nuclear Information System (INIS)

Aggarwal, J.; Sheppard, D.S.; Robinson, B.W.

1998-01-01

Methods are documented for the analysis of B isotopes, O and N isotopes in nitrates. B isotopes can be measured by negative ion thermal ionisation mass spectrometry. Nitrate is recovered from groundwaters by ion exchange and the resulting silver nitrate combusted for stable isotope gas analysis. Oxygen isotope analysis of phosphates can be determined by generating and analysing CO 2 gas from the combustion of silver phosphate produced from aqueous samples. Sulphate in ground and surface waters can be separated and concentrated by ion exchange and precipitated as barium sulphate. This is reacted with graphite to yield CO 2 and CO, the latter being spark discharged to CO 2 and the total CO 2 measured for oxygen isotope analysis. Barium sulphide from this reaction is converted to silver sulphide which is reacted with cuprous oxide to give SO 2 gas for sulphur isotope measurements. A case study of the semi-rural Manakau area in New Zealand was conducted to see if nitrate isotopes could be used to detect the source of nitrate contamination (groundwater nitrate - 3- N). Nitrogen isotope (+4 to +12 per mille) coupled with oxygen isotope measurements (+5 to +9 per mille) demonstrated that the nitrogen is not sources from fertilisers but from some combination of septic tank and animal waste. For the case study of sulphate isotope use, sulphur and oxygen isotopic compositions of sulphate in river and lake water from seven major catchments of New Zealand were determined. The isotope analyses have allowed the distinction between natural (geological, geothermal and volcanic) and anthropogenic (fertiliser) sulphur sources. (author)

Radiation induced changes in plasma total protein nitrogen and urinary total nitrogen in desert rodent and albino rats subjected to dietary protein deficiency

International Nuclear Information System (INIS)

Roushdy, H.; El-Husseini, M.; Saleh, F.

1986-01-01

The effect of gamma-irradiation on plasma total protein nitrogen and urinary total nitrogen was studied in the desert rodent, psammomy obesus obesus and albino rats subjected to dietary protein deficiency. In albino rats kept on high protein diet, the radiation syndrome resulted in urine retention, while in those kept on non-protein diet, such phenomenon was recorded only with the high radiation level of 1170r. Radiation exposure to 780 and 1170r caused remarkable diuresis in psammomys obesus obesus whereas they induced significant urine retention in albino rats. The levels of plasma total protein nitrogen and urinary total nitrogen were higher in albino rats maintained on high protein diet than in those kept on non-protein diet. Radiation exposure caused an initial drop in plasma total protein nitrogen concentration, concomitant with an initial rise in total urinary nitrogen, radiation exposure of psammomys obesus obesus caused significant increase in the levels of plasma protein nitrogen and urinary total nitrogen. Psammomys obesus obesus seemed to be more affected by radiation exposure than did the albino rats

Effects of Mulching and Nitrogen on Soil Nitrate-N Distribution, Leaching and Nitrogen Use Efficiency of Maize (Zea mays L..

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Xiukang Wang

Full Text Available Mulching and nitrogen are critical drivers of crop production for smallholders of the Loess Plateau in China. The purpose of this study was to investigate the effect of mulching and nitrogen fertilizer on the soil water content, soil nitrate-N content and vertical distribution in maize root-zone. The experiment was conducted over two consecutive years and used randomly assigned field plots with three replicates. The six treatments consisted of no fertilizer without plastic film (CK, plastic film mulching with no basal fertilizer and no top dressing (MN0, basal fertilizer with no top dressing and no mulching (BN1, plastic film mulching and basal fertilizer with no top dressing (MN1, basal fertilizer and top dressing with no mulching (BN2 and plastic film mulching with basal fertilizer and top dressing (MN2. In the top soil layers, the soil water content was a little high in the plastic film mulching than that without mulching. The mean soil water content from 0 to 40 cm without mulching were 3.35% lower than those measured in the corresponding mulching treatments in 31 days after sowing in 2012. The mulching treatment increased the soil nitrate-N content was observed in the 0-40-cm soil layers. The results indicate that high contents of soil nitrate-N were mainly distributed at 0-20-cm at 31 days after sowing in 2012, and the soil nitrate-N concentration in the MN2 treatment was 1.58 times higher than that did not receive fertilizer. The MN2 treatment greatly increased the soil nitrate-N content in the upper layer of soil (0-40-cm, and the mean soil nitrate-N content was increased nearly 50 mg kg-1 at 105 days after sowing compared with CK treatment in 2012. The soil nitrate-N leaching amount in MN1 treatment was 28.61% and 39.14% lower than BN1 treatment, and the mulch effect attained to 42.55% and 65.27% in MN2 lower than BN2 in both years. The yield increased with an increase in the basal fertilizer, top dressing and plastic film mulching, and

Nitrogen metabolism in a grapevine in vitro system

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Nuria Llorens

2002-09-01

Full Text Available Ammonium, nitrate, nitrite, protein and individual and total amino acid contents were determined in grapevine (cv Sauvignon cultured in vitro. The enzyme activities of nitrate and nitrite reductases, glutamine synthetase, glutamate synthetase and dehydrogenase were also determined. The nitrogen taken up by the plants was 70% of the total nitrogen in the medium after 75 days of in vitro culture. Most of the nitrogen taken up was recovered in the leaves, yet only ammonia and amino acid concentrations were significantly higher in leaves. In roots, glutamine was the most abundant amino acid. In leaves, the most abundant amino acids were aspartate, glutamate, glutamine, alanine, arginine and g-aminobutirate. All enzyme activities were higher in roots than in leaves. These results suggest that both roots and leaves incorporate inorganic nitrogen into organic forms.

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

Science.gov (United States)

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

2018-02-06

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

High Nitrogen Fertilization of Tobacco Crop in Headwater Watershed Contaminates Subsurface and Well Waters with Nitrate

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D. R. Kaiser

2015-01-01

Full Text Available Our hypothesis was that subsurface and well waters in watershed with shallow, stony soils, steep landscapes, and cropped to tobacco are contaminated by nitrate. Nitrate in soil solution was monitored in (0.20 m and below (0.5 m root zone with tension lysimeters, in five transects. Water from two wells (beneath tobacco field and in native forest used for human consumption was also analyzed for nitrate. Soil bulk density, porosity, and saturated hydraulic conductivity were evaluated. Soil physical and hydrological properties showed great variation at different landscape positions and soil depths. Soil coarse grain size, high porosity, and saturated hydraulic conductivity favored leaching nitrate. Nitrate in soil solution from tobacco fields was greater than in natural environment. Nitrate reached depths bellow rooting zone with values as high as 80 mg L−1 in tobacco plantation. Water well located below tobacco plantation had high nitrate concentration, sometimes above the critical limit of 10 mg L−1. Tobacco cropping causes significant water pollution by nitrate, posing risk to human health. A large amount of nitrogen fertilizers applied to tobacco and nitrate in subsurface waters demonstrate the unsustainability of tobacco production in small farming units on steeps slopes, with stony and shallow soils.

The impact of the Nitrates Directive on nitrogen emissions from agriculture in the EU-27 during 2000-2008.

Science.gov (United States)

Velthof, G L; Lesschen, J P; Webb, J; Pietrzak, S; Miatkowski, Z; Pinto, M; Kros, J; Oenema, O

2014-01-15

A series of environmental policies have been implemented in the European Union (EU) to decrease nitrogen (N) emissions from agriculture. The Nitrates Directive (ND) is one of the main policies; it aims to reduce nitrate leaching from agriculture through a number of measures. A study was carried out to quantify the effects of the ND in the EU-27 on the leaching and runoff of nitrate (NO3(-)) to groundwater and surface waters, and on the emissions of ammonia (NH3), nitrous oxide (N2O), nitrogen oxides (NO(x)) and dinitrogen (N2) to the atmosphere. We formulated a scenario with and a scenario without implementation of the ND. The model MITERRA-Europe was used to calculate N emissions on a regional level in the EU-27 for the period 2000-2008. The calculated total N loss from agriculture in the EU-27 was 13 Mton N in 2008, with 53% as N2, 22% as NO3, 21% as NH3, 3% as N2O, and 1% as NO(x). The N emissions and leaching in the EU-27 slightly decreased in the period 2000-2008. Total emissions in the EU in 2008 were smaller with implementation of the ND than without the ND, by 3% for NH3, 6% for N2O, 9% for NO(x), and 16% for N leaching and runoff in 2008. However, regional differences were large. The lower emissions with ND were mainly due to the lower N inputs by fertilizers and manures. In conclusion, implementation of the ND decreased both N leaching losses to ground and surface waters, and gaseous emissions to the atmosphere. It is expected that the ND will result in a further decrease in N emissions in EU-27 in the near future, because the implementation of the measures for the ND is expected to become more strict. Copyright © 2013 Elsevier B.V. All rights reserved.

Loads of nitrate, phosphorus, and total suspended solids from Indiana watersheds

Science.gov (United States)

Bunch, Aubrey R.

2016-01-01

Transport of excess nutrients and total suspended solids (TSS) such as sediment by freshwater systems has led to degradation of aquatic ecosystems around the world. Nutrient and TSS loads from Midwestern states to the Mississippi River are a major contributor to the Gulf of Mexico Hypoxic Zone, an area of very low dissolved oxygen concentration in the Gulf of Mexico. To better understand Indiana’s contribution of nutrients and TSS to the Mississippi River, annual loads of nitrate plus nitrite as nitrogen, total phosphorus, and TSS were calculated for nine selected watersheds in Indiana using the load estimation model, S-LOADEST. Discrete water-quality samples collected monthly by the Indiana Department of Environmental Management’s Fixed Stations Monitoring Program from 2000–2010 and concurrent discharge data from the U. S. Geological Survey streamflow gages were used to create load models. Annual nutrient and TSS loads varied across Indiana by watershed and hydrologic condition. Understanding the loads from large river sites in Indiana is important for assessing contributions of nutrients and TSS to the Mississippi River Basin and in determining the effectiveness of best management practices in the state. Additionally, evaluation of loads from smaller upstream watersheds is important to characterize improvements at the local level and to identify priorities for reduction.

Real-time continuous nitrate monitoring in Illinois in 2013

Science.gov (United States)

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.

Utility of the end-of-season nitrate test for nitrogen sufficiency of irrigated maize under Mediterranean semi-arid conditions

Energy Technology Data Exchange (ETDEWEB)

Isla, R.; Salmeron, M.; Cavero, J.; Yagüe, M.R.; Quilez, D.

2015-07-01

Calibration of decision tools to improve N fertilizer management is critical to increase its adoption by maize (Zea mays L.) growers. The objective of this study was to establish nitrate and total nitrogen concentrations in the basal maize stalks (BMS) at harvest to separate maize fields among three N availability categories (N-deficient, N-optimum, and N-excess) under Mediterranean irrigated semiarid conditions. We analysed data from 26 irrigated maize trials conducted between 2001 and 2012. Trials included treatments receiving different N fertilizer rates and sources (mineral and organic), irrigation systems (flood, sprinkler) and soil types. The critical nitrate concentration in BMS to identify N-deficient plots (CNCL) is affected by the irrigation system. The CNCL was lower under sprinkler irrigation (708 mg NO{sub 3}{sup -}–N/kg) than under flood irrigation (2205 mg NO{sub 3}{sup -}–N/kg), and the later presented a higher degree of uncertainty compared to sprinkler irrigated systems. The results showed the difficulty to identify the N-deficient plots with the BMS test and the higher sensibility of nitrate-N than total-N concentration in BMS to separate N-deficient from N-optimal plots. Under sprinkler irrigation, nitrate in BMS>1500 mg NO{sub 3}{sup -}–N/kg had a 85% probability of having received an excess of N. Considering economic net returns to N fertilization, the range of nitrate concentration in BMS that maximized profit under sprinkler-irrigated conditions was established between 1100 and 1700 mg NO3-–N/kg. Results suggest that BMS test can be useful in detecting plots with an excess of N but considering irrigation efficiency is crucial for stablishing successful CNC thresholds. (Author)

Simultaneous Measurement of Nitrogen and Oxygen Isotopes of Nitrate to Evaluate Nitrate Sources and Processes in Catchments

Energy Technology Data Exchange (ETDEWEB)

Ohte, Nobuhito [Graduate School of Agricultural and Life Sciences, University of Tokyo, Tokyo (Japan); Nagata, Toshi; Tayasu, Ichiro [Center for Ecological Research, Kyoto University, Ohtsu (Japan); Kyozu, Ayato; Yoshimizu, Chikage [CREST, Japan Science and Technology Agency, Center for Ecological Research, Kyoto University, Ohtsu (Japan); Osaka, Ken' ichi [Carbon and Nutrient Cycles Division, National Institute for Agro-Environmental Sciences, Tsukuba, (Japan)

2013-05-15

We review studies on applied isotope analytical techniques for identifying sources and transformations of river nitrate (NO{sub 3}{sup -}) to examine the influences of water pollution, excess nutrient (nitrogen) loads and ecosystem disturbances in river systems. We also discuss the current status and future perspectives of the application of NO{sub 3}{sup -} isotope measurements to the assessment of river nutrients. Our review shows that in recent years simultaneous measurements of nitrogen and oxygen isotopes ({delta}{sup 15}N and {delta}{sup 18}O) of NO{sub 3}{sup -} have been increasingly used to identify the sources and pathways of nitrogen in river systems. The {delta}{sup 15}N value of NO{sub 3}{sup -} is a useful indicator to evaluate the contributions of sewage and/or animal waste to NO{sub 3}{sup -} load, and the {delta}{sup 18}O value can be used for estimation of the contribution of NO{sub 3}{sup -} derived through atmospheric deposition. The microbial denitrification method is currently a most useful tool to measure the {delta}{sup 15}N and {delta}{sup 18}O values of NO{sub 3}{sup -} simultaneously, because of its capability for high throughput of samples. This method allows us to conduct a comprehensive investigation of spatial and temporal variations and mechanisms of nitrogen transport and transformation in rivers and catchments in more precise and effective manner. (author)

Are nitrate exports in stream water linked to nitrogen fluxes in decomposing foliar litter?

Science.gov (United States)

Kathryn B. Piatek; Mary Beth. Adams

2011-01-01

The central hardwood forest receives some of the highest rates of atmospheric nitrogen (N) deposition, which results in nitrate leaching to surface waters. Immobilization of N in foliar litter during litter decomposition represents a potential mechanism for temporal retention of atmospherically deposited N in forest ecosystems. When litter N dynamics switch to the N-...

Strategies to increase nitrogen use efficiency and reduce nitrate leaching in vegetable production in the Netherlands

NARCIS (Netherlands)

Ruijter, de F.J.; Berge, ten H.F.M.; Smit, A.L.

2010-01-01

Environmental concern and legislation of fertilization requires strategies to increase nitrogen use efficiency and reduce nitrate leaching. Strategies can be fertilizer choice, timing of N availability and fertilizer placement. Rainfall in the experimental year 2007 was moderate and different

Nitrate-nitrogen contamination in groundwater: Spatiotemporal variation and driving factors under cropland in Shandong Province, China

Science.gov (United States)

Liu, J.; Jiang, L. H.; Zhang, C. J.; Li, P.; Zhao, T. K.

2017-08-01

High groundwater nitrate-N is a serious problem especially in highly active agricultural areas. In study, the concentration and spatialtemporal distribution of groundwater nitrate-N under cropland in Shandong province were assessed by statistical and geostatistical techniques. Nitrate-N concentration reached a maximum of 184.60 mg L-1 and 29.5% of samples had levels in excess of safety threshold concentration (20 mg L-1). The median nitrate-N contents after rainy season were significantly higher than those before rainy season, and decreased with increasing groundwater depth. Nitrate-N under vegetable and orchard area are significantly higher than ones under grain. The kriging map shows that groundwater nitrate-N has a strong spatial variability. Many districts, such as Weifang, Linyi in Shandong province are heavily contaminated with nitrate-N. However, there are no significant trends of NO3 --N for most cities. Stepwise regression analysis showed influencing factors are different for the groundwater in different depth. But overall, vegetable yield per unit area, percentages of orchard area, per capita agricultural production, unit-area nitrogen fertilizer, livestock per unit area, percentages of irrigation areas, population per unit area and annual mean temperature are significant variables for groundwater nitrate-N variation.

Simultaneous effect of nitrate (NO3- concentration, carbon dioxide (CO2 supply and nitrogen limitation on biomass, lipids, carbohydrates and proteins accumulation in Nannochloropsis oculata

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Aarón Millán-Oropeza

2015-03-01

Full Text Available Biodiesel from microalgae is a promising technology. Nutrient limitation and the addition of CO2 are two strategies to increase lipid content in microalgae. There are two different types of nitrogen limitation, progressive and abrupt limitation. In this work, the simultaneous effect of initial nitrate concentration, addition of CO2, and nitrogen limitation on biomass, lipid, protein and carbohydrates accumulation were analyzed. An experimental design was established in which initial nitrogen concentration, culture time and CO2 aeration as independent numerical variables with three levels were considered. Nitrogen limitation was taken into account as a categorical independent variable. For the experimental design, all the experiments were performed with progressive nitrogen limitation. The dependent response variables were biomass, lipid production, carbohydrates and proteins. Subsequently, comparison of both types of limitation i.e. progressive and abrupt limitation, was performed. Nitrogen limitation in a progressive mode exerted a greater effect on lipid accumulation. Culture time, nitrogen limitation and the interaction of initial nitrate concentration with nitrogen limitation had higher influences on lipids and biomass production. The highest lipid production and productivity were at 582 mgL-1 (49.7 % lipid, dry weight basis and 41.5 mgL-1d-1, respectively; under the following conditions: 250 mgL-1 of initial nitrate concentration, CO2 supply of 4% (v/v, 12 d of culturing and 2 d in state of nitrogen starvation induced by progressive limitation. This work presents a novel way to perform simultaneous analysis of the effect of the initial concentration of nitrate, nitrogen limitation, and CO2 supply on growth and lipid production of Nannochloropsis oculata, with the aim to produce potential biofuels feedstock.

Determinação das formas de nitrogênio e nitrogênio total em rochas-reservatório de petróleo por destilação com arraste de vapor e método do indofenol Determination of nitrogen forms and total nitrogen in petroleum reservoir rocks by steam distillation and the indophenol method

Directory of Open Access Journals (Sweden)

Lílian Irene Dias da Silva

2006-02-01

Full Text Available Several extraction procedures are described for the determination of exchangeable and fixed ammonium, nitrate + nitrite, total exchangeable nitrogen and total nitrogen in certified reference soils and petroleum reservoir rock samples by steam distillation and indophenol method. After improvement of the original distillation system, an increase in worker safety, a reduction in time consumption, a decrease of 73% in blank value and an analysis without ammonia loss, which could possibly occur, were achieved. The precision (RSD < 8%, n = 3 and the detection limit (9 mg kg-1 NH4+-N are better than those of published procedures.

Bayesian Nitrate Source Apportionment to Individual Groundwater Wells in the Central Valley by use of Nitrogen, Oxygen, and Boron Isotopic Tracers

Science.gov (United States)

Lockhart, K.; Harter, T.; Grote, M.; Young, M. B.; Eppich, G.; Deinhart, A.; Wimpenny, J.; Yin, Q. Z.

2014-12-01

Groundwater quality is a concern in alluvial aquifers underlying agricultural areas worldwide, an example of which is the San Joaquin Valley, California. Nitrate from land applied fertilizers or from animal waste can leach to groundwater and contaminate drinking water resources. Dairy manure and synthetic fertilizers are the major sources of nitrate in groundwater in the San Joaquin Valley, however, septic waste can be a major source in some areas. As in other such regions around the world, the rural population in the San Joaquin Valley relies almost exclusively on shallow domestic wells (≤150 m deep), of which many have been affected by nitrate. Consumption of water containing nitrate above the drinking water limit has been linked to major health effects including low blood oxygen in infants and certain cancers. Knowledge of the proportion of each of the three main nitrate sources (manure, synthetic fertilizer, and septic waste) contributing to individual well nitrate can aid future regulatory decisions. Nitrogen, oxygen, and boron isotopes can be used as tracers to differentiate between the three main nitrate sources. Mixing models quantify the proportional contributions of sources to a mixture by using the concentration of conservative tracers within each source as a source signature. Deterministic mixing models are common, but do not allow for variability in the tracer source concentration or overlap of tracer concentrations between sources. Bayesian statistics used in conjunction with mixing models can incorporate variability in the source signature. We developed a Bayesian mixing model on a pilot network of 32 private domestic wells in the San Joaquin Valley for which nitrate as well as nitrogen, oxygen, and boron isotopes were measured. Probability distributions for nitrogen, oxygen, and boron isotope source signatures for manure, fertilizer, and septic waste were compiled from the literature and from a previous groundwater monitoring project on several

The Nitrate-Inducible NAC Transcription Factor TaNAC2-5A Controls Nitrate Response and Increases Wheat Yield1[OPEN

Science.gov (United States)

He, Xue; Qu, Baoyuan; Li, Wenjing; Zhao, Xueqiang; Teng, Wan; Ma, Wenying; Ren, Yongzhe; Li, Bin; Li, Zhensheng; Tong, Yiping

2015-01-01

Nitrate is a major nitrogen resource for cereal crops; thus, understanding nitrate signaling in cereal crops is valuable for engineering crops with improved nitrogen use efficiency. Although several regulators have been identified in nitrate sensing and signaling in Arabidopsis (Arabidopsis thaliana), the equivalent information in cereals is missing. Here, we isolated a nitrate-inducible and cereal-specific NAM, ATAF, and CUC (NAC) transcription factor, TaNAC2-5A, from wheat (Triticum aestivum). A chromatin immunoprecipitation assay showed that TaNAC2-5A could directly bind to the promoter regions of the genes encoding nitrate transporter and glutamine synthetase. Overexpression of TaNAC2-5A in wheat enhanced root growth and nitrate influx rate and, hence, increased the root’s ability to acquire nitrogen. Furthermore, we found that TaNAC2-5A-overexpressing transgenic wheat lines had higher grain yield and higher nitrogen accumulation in aerial parts and allocated more nitrogen in grains in a field experiment. These results suggest that TaNAC2-5A is involved in nitrate signaling and show that it is an exciting gene resource for breeding crops with more efficient use of fertilizer. PMID:26371233

A hybrid machine learning model to predict and visualize nitrate concentration throughout the Central Valley aquifer, California, USA

Science.gov (United States)

Ransom, Katherine M.; Nolan, Bernard T.; Traum, Jonathan A.; Faunt, Claudia; Bell, Andrew M.; Gronberg, Jo Ann M.; Wheeler, David C.; Zamora, Celia; Jurgens, Bryant; Schwarz, Gregory E.; Belitz, Kenneth; Eberts, Sandra; Kourakos, George; Harter, Thomas

2017-01-01

Intense demand for water in the Central Valley of California and related increases in groundwater nitrate concentration threaten the sustainability of the groundwater resource. To assess contamination risk in the region, we developed a hybrid, non-linear, machine learning model within a statistical learning framework to predict nitrate contamination of groundwater to depths of approximately 500 m below ground surface. A database of 145 predictor variables representing well characteristics, historical and current field and landscape-scale nitrogen mass balances, historical and current land use, oxidation/reduction conditions, groundwater flow, climate, soil characteristics, depth to groundwater, and groundwater age were assigned to over 6000 private supply and public supply wells measured previously for nitrate and located throughout the study area. The boosted regression tree (BRT) method was used to screen and rank variables to predict nitrate concentration at the depths of domestic and public well supplies. The novel approach included as predictor variables outputs from existing physically based models of the Central Valley. The top five most important predictor variables included two oxidation/reduction variables (probability of manganese concentration to exceed 50 ppb and probability of dissolved oxygen concentration to be below 0.5 ppm), field-scale adjusted unsaturated zone nitrogen input for the 1975 time period, average difference between precipitation and evapotranspiration during the years 1971–2000, and 1992 total landscape nitrogen input. Twenty-five variables were selected for the final model for log-transformed nitrate. In general, increasing probability of anoxic conditions and increasing precipitation relative to potential evapotranspiration had a corresponding decrease in nitrate concentration predictions. Conversely, increasing 1975 unsaturated zone nitrogen leaching flux and 1992 total landscape nitrogen input had an increasing relative

Symbiotic nitrogen fixation and nitrate uptake by the pea crop

International Nuclear Information System (INIS)

Jensen, E.S.

1986-08-01

Symbiotic nitrogen fixation and nitrate uptake by pea plants (Pisum sativum L.) were studied in field and pot experiments using the 15 N isotope dilution technique and spring barley as a non-fixing reference crop. Barley, although not ideal, seemed to be a suitable reference for pea in the 15 N-technique. Maximum N 2 fixation activity of 10 kg N fixed per ha per day was reached around the flat pod growth stage, and the activity decreased rapidly during pod-filling. The pea crop fixed between 100 and 250 kg N ha -1 , corresponding to from 45 to 80 per cent of total crop N. The amount of symbiotically fixed N 2 depended on the climatic conditions in the experimental year, the level of soil mineral N and the pea cultivar. Field-grown pea took up 60 to 70 per cent of the N-fertilizer supplied. The supply of 50 kg NO 3 -N ha -1 inhibited the N 2 fixation approximately 15 per cent. Small amounts of fertilizer N, supplied at sowing (starter-N), slightly stimulated the vegetative growth of pea, but the yields of seed dry matter and protein were not significantly influenced. In the present field experiments the environmental conditions, especially the distribution of rainfall during the growth season, seemed to be more important in determining the protein and dry matter yield of the dry pea crop, than the ability of pea to fix nitrogen symbiotically. However, fertilizer N supplied to pot-grown pea plants at the flat pod growth stage or as split applications significantly increased the yield of seed dry matter and protein. (author)

Ammonia volatilization from surface-applied nitrogen solution of urea and ammonium nitrate

International Nuclear Information System (INIS)

Trivellin, Paulo Cezar Ocheuze; Stefanutti, Ronaldo; Lima Filho, Oscar Fontvo de; Tziboy, Edgar Alfredo Tzi; Oliveira Junior, Jovo Alberto de; Bendassolli, Jose Albertino

1996-08-01

The urea is one of the fertilizers more utilized in modern agriculture. One of the problems in the urea utilization is the ammonium volatilization, resulting in low utilization of N-fertilizers by the plants.The objective of this study it was to evaluate and to compare in laboratories conditions , utilizing the 15 N technic the soil's ammonium lost by volatilization associated a superficial application of nitrogen corresponding doses like urea solution and urea and ammonium nitrates solution

Control strategies for the reduction of airborne particulate nitrate in California's San Joaquin Valley

Science.gov (United States)

Kleeman, Michael J.; Ying, Qi; Kaduwela, Ajith

The effect of NO x, volatile organic compound (VOC), and NH 3 emissions control programs on the formation of particulate ammonium nitrate in the San Joaquin Valley (SJV) was examined under the typical winter conditions that existed on 4-6 January, 1996. The UCD/CIT photochemical transport model was used for this study so that the source origin of primary particulate matter and secondary particulate matter could be identified. When averaged across the entire SJV, the model results predict that 13-18% of the reactive nitrogen (NO y=NO x+reaction products of NO x) emitted from local sources within the SJV was converted to nitrate at the ground level. Each gram of NO x emitted locally within the SJV (expressed as NO 2) produced 0.23-0.31 g of particulate ammonium nitrate (NH 4NO 3), which is much smaller than the maximum theoretical yield of 1.7 g of NH 4NO 3 per gram of NO 2. The fraction of reactive nitrogen converted to nitrate varied strongly as a function of location. Urban regions with large amounts of fresh NO emissions converted little reactive nitrogen to nitrate, while remote areas had up to 70% conversion (equivalent to approximately 1.2 g of NH 4NO 3 per gram of NO 2). The use of a single spatially averaged ratio of NH 4NO 3/NO x as a predictor of how changes to NO x emissions would affect particulate nitrate concentrations would not be accurate at all locations in the SJV under the conditions studied. The largest local sources of particulate nitrate in the SJV were predicted to be diesel engines and catalyst equipped gasoline engines under the conditions experienced on 6 January, 1996. Together, these sources accounted for less than half of the ground-level nitrate aerosol in the SJV. The remaining fraction of the aerosol nitrate originated from reactive nitrogen originally released upwind of the SJV. The majority of this upwind reactive nitrogen was already transformed to nitrate by the time it entered the SJV. The effect of local emissions controls on

Mineral commodity profiles: nitrogen

Science.gov (United States)

Kramer, Deborah A.

2004-01-01

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

Nitrogen nutrition of Canna indica: Effects of ammonium versus nitrate on growth, biomass allocation, photosynthesis, nitrate reductase activity and N uptake rates

DEFF Research Database (Denmark)

Konnerup, Dennis; Brix, Hans

2010-01-01

The effects of inorganic nitrogen (N) source (NH4+, NO3- or both) on growth, biomass allocation, photosynthesis, N uptake rate, nitrate reductase activity and mineral composition of Canna indica were studied in hydroponic culture. The relative growth rates (0.05-0.06 g g-1 d-1), biomass allocation...

Management, regulation and environmental impacts of nitrogen fertilization in northwestern Europe under the Nitrates Directive; a benchmark study

Directory of Open Access Journals (Sweden)

H. J. M. van Grinsven

2012-12-01

Full Text Available Implementation of the Nitrates Directive (NiD and its environmental impacts were compared for member states in the northwest of the European Union (Ireland, United Kingdom, Denmark, the Netherlands, Belgium, Northern France and Germany. The main sources of data were national reports for the third reporting period for the NiD (2004–2007 and results of the MITERRA-EUROPE model. Implementation of the NiD in the considered member states is fairly comparable regarding restrictions for where and when to apply fertilizer and manure, but very different regarding application limits for N fertilization. Issues of concern and improvement of the implementation of the NiD are accounting for the fertilizer value of nitrogen in manure, and relating application limits for total nitrogen (N to potential crop yield and N removal. The most significant environmental effect of the implementation of the NiD since 1995 is a major contribution to the decrease of the soil N balance (N surplus, particularly in Belgium, Denmark, Ireland, the Netherlands and the United Kingdom. This decrease is accompanied by a modest decrease of nitrate concentrations since 2000 in fresh surface waters in most countries. This decrease is less prominent for groundwater in view of delayed response of nitrate in deep aquifers. In spite of improved fertilization practices, the southeast of the Netherlands, the Flemish Region and Brittany remain to be regions of major concern in view of a combination of a high nitrogen surplus, high leaching fractions to groundwater and tenacious exceedance of the water quality standards. On average the gross N balance in 2008 for the seven member states in EUROSTAT and in national reports was about 20 kg N ha⁻¹ yr⁻¹ lower than by MITERRA. The major cause is higher estimates of N removal in national reports which can amount to more than 50 kg N ha⁻¹ yr⁻¹. Differences between procedures in member states to

Management, regulation and environmental impacts of nitrogen fertilization in northwestern Europe under the Nitrates Directive; a benchmark study

Science.gov (United States)

van Grinsven, H. J. M.; ten Berge, H. F. M.; Dalgaard, T.; Fraters, B.; Durand, P.; Hart, A.; Hofman, G.; Jacobsen, B. H.; Lalor, S. T. J.; Lesschen, J. P.; Osterburg, B.; Richards, K. G.; Techen, A.-K.; Vertès, F.; Webb, J.; Willems, W. J.

2012-12-01

Implementation of the Nitrates Directive (NiD) and its environmental impacts were compared for member states in the northwest of the European Union (Ireland, United Kingdom, Denmark, the Netherlands, Belgium, Northern France and Germany). The main sources of data were national reports for the third reporting period for the NiD (2004-2007) and results of the MITERRA-EUROPE model. Implementation of the NiD in the considered member states is fairly comparable regarding restrictions for where and when to apply fertilizer and manure, but very different regarding application limits for N fertilization. Issues of concern and improvement of the implementation of the NiD are accounting for the fertilizer value of nitrogen in manure, and relating application limits for total nitrogen (N) to potential crop yield and N removal. The most significant environmental effect of the implementation of the NiD since 1995 is a major contribution to the decrease of the soil N balance (N surplus), particularly in Belgium, Denmark, Ireland, the Netherlands and the United Kingdom. This decrease is accompanied by a modest decrease of nitrate concentrations since 2000 in fresh surface waters in most countries. This decrease is less prominent for groundwater in view of delayed response of nitrate in deep aquifers. In spite of improved fertilization practices, the southeast of the Netherlands, the Flemish Region and Brittany remain to be regions of major concern in view of a combination of a high nitrogen surplus, high leaching fractions to groundwater and tenacious exceedance of the water quality standards. On average the gross N balance in 2008 for the seven member states in EUROSTAT and in national reports was about 20 kg N ha-1 yr-1 lower than by MITERRA. The major cause is higher estimates of N removal in national reports which can amount to more than 50 kg N ha-1 yr-1. Differences between procedures in member states to assess nitrogen balances and water quality and a lack of cross

Identifying sources of subsurface nitrate pollution with stable nitrogen isotopes. Final report, August 1976-March 1978

International Nuclear Information System (INIS)

Wolterink, T.J.; Williamson, H.J.; Jones, D.C.; Grimshaw, T.W.; Holland, W.F.

1979-08-01

This report describes the methods, results, conclusions, and recommendations of an investigation of a technique to identify sources of nitrate in ground water. A discussion of the theoretical basis of the technique is also provided. Over 300 soil and ground water samples were collected for this study. The samples are from numerous sites around the United States, representing a variety of environmental conditions. The nitrate in 66 of these samples was separated from other nitrogen species, converted to N2 gas, purified, and analyzed to determine the ratio (15)N/(14)N. These data were combined with the results of analyses performed previously by Jones (1) and Kreitler (2). Standard statistical techniques were used to analyze the observed variations in delta (15)N values, with respect to several nitrate sources and various environmental factors. It was found that nitrates from feedlots, barnyards and septic tanks can be distinguished from natural soil nitrates on the basis of their delta (15)N values. They cannot, however, be distinguished from each other. Environmental factors contributed to the observed variation in delta (15)N values

Nitrogen stress triggered biochemical and morphological changes in the microalgae Scenedesmus sp. CCNM 1077.

Science.gov (United States)

Pancha, Imran; Chokshi, Kaumeel; George, Basil; Ghosh, Tonmoy; Paliwal, Chetan; Maurya, Rahulkumar; Mishra, Sandhya

2014-03-01

The aim of present study was to investigate the effects of nitrogen limitation as well as sequential nitrogen starvation on morphological and biochemical changes in Scenedesmus sp. CCNM 1077. The results revealed that the nitrogen limitation and sequential nitrogen starvation conditions significantly decreases the photosynthetic activity as well as crude protein content in the organism, while dry cell weight and biomass productivity are largely unaffected up to nitrate concentration of about 30.87mg/L and 3 days nitrate limitation condition. Nitrate stress was found to have a significant effect on cell morphology of Scenedesmus sp. CCNM 1077. Total removal of nitrate from the growth medium resulted in highest lipid (27.93%) and carbohydrate content (45.74%), making it a potential feed stock for biodiesel and bio-ethanol production. This is a unique approach to understand morphological and biochemical changes in freshwater microalgae under nitrate limitation as well as sequential nitrate removal conditions. Copyright © 2014 Elsevier Ltd. All rights reserved.

Achieving low effluent NO3-N and TN concentrations in low influent chemical oxygen demand (COD) to total Kjeldahl nitrogen (TKN) ratio without using external carbon source

Science.gov (United States)

Cao, Jiashun; Oleyiblo, Oloche James; Xue, Zhaoxia; Otache, Y. Martins; Feng, Qian

2015-07-01

Two mathematical models were used to optimize the performance of a full-scale biological nutrient removal (BNR) activated treatment plant, a plug-flow bioreactors operated in a 3-stage phoredox process configuration, anaerobic anoxic oxic (A2/O). The ASM2d implemented on the platform of WEST2011 software and the BioWin activated sludge/anaerobic digestion (AS/AD) models were used in this study with the aim of consistently achieving the designed effluent criteria at a low operational cost. Four ASM2d parameters (the reduction factor for denitrification , the maximum growth rate of heterotrophs (µH), the rate constant for stored polyphosphates in PAOs ( q pp), and the hydrolysis rate constant ( k h)) were adjusted. Whereas three BioWin parameters (aerobic decay rate ( b H), heterotrophic dissolved oxygen (DO) half saturation ( K OA), and Y P/acetic) were adjusted. Calibration of the two models was successful; both models have average relative deviations (ARD) less than 10% for all the output variables. Low effluent concentrations of nitrate nitrogen (N-NO3), total nitrogen (TN), and total phosphorus (TP) were achieved in a full-scale BNR treatment plant having low influent chemical oxygen demand (COD) to total Kjeldahl nitrogen (TKN) ratio (COD/TKN). The effluent total nitrogen and nitrate nitrogen concentrations were improved by 50% and energy consumption was reduced by approximately 25%, which was accomplished by converting the two-pass aerobic compartment of the plug-flow bioreactor to anoxic reactors and being operated in an alternating mode. Findings in this work are helpful in improving the operation of wastewater treatment plant while eliminating the cost of external carbon source and reducing energy consumption.

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

Science.gov (United States)

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

2014-05-01

Field drains are often considered to short circuit the hydrological cycle in agricultural catchments and lead to an increased risk of nitrogen loss to the environment. Because of increased regulation of agricultural practices due to catchment management plans, resulting from the implementation of the water frame directive, Danish farmers pushed for a large scale monitoring of nitrogen loss from field drains. Therefore, the knowledge centre for agriculture, Denmark, organized a three year campaign where farmers and local agricultural advisory centres collected water samples from field drains three to five times during the winter season. Samples were analysed for nitrate and total nitrogen. Combined, more than 600 drains were monitored over the three years. During the first two years of monitoring, average winter concentrations of total nitrogen ranged from 0.1 mg N L-1 to 31.1 mg N L-1, and the fraction of total nitrogen present as nitrate ranged from 0% to 100%. This variation is much larger than what is observed in the Danish national monitoring and assessment programme, which monitors only a few drains in selected catchments. Statistical analysis revealed that drainage water nitrogen concentrations were significantly correlated to the cropping system and the landscape type (high ground/lowlands/raised seabed) in which the monitored fields were situated. The average total nitrogen concentration was more than 2 mg N L-1 lower on raised seabed than on high ground, and the average fraction of total nitrogen present as nitrate was more than 20% lower. This indicates that substantial nitrate reduction occurs at or above the drain depth on raised sea flats, in particular in the north of Denmark. This inherent nitrogen retention on raised seabed is not taken into account in the current environmental regulation, nor in the first generation catchment management plans. The monitoring program demonstrated large variation in nitrogen concentrations in drainage water, in

Identification of nitrate sources and discharge-depending nitrate dynamics in a mesoscale catchment

Science.gov (United States)

Mueller, Christin; Strachauer, Ulrike; Brauns, Mario; Musolff, Andreas; Kunz, Julia Vanessa; Brase, Lisa; Tarasova, Larisa; Merz, Ralf; Knöller, Kay

2017-04-01

During the last decades, nitrate concentrations in surface and groundwater have increased due to land use change and accompanying application of fertilizer in agriculture as well as increased atmospheric deposition. To mitigate nutrient impacts on downstream aquatic ecosystems, it is important to quantify potential nitrate sources, instream nitrate processing and its controls in a river system. The objective of this project is to characterize and quantify (regional) scale dynamics and trends in water and nitrogen fluxes of the entire Holtemme river catchment in central Germany making use of isotopic fingerprinting methods. Here we compare two key date sampling campaigns in 2014 and 2015, with spatially highly resolved measurements of discharge at 23 sampling locations including 11 major tributaries and 12 locations at the main river. Additionally, we have data from continuous runoff measurements at 10 locations operated by the local water authorities. Two waste water treatment plants contribute nitrogen to the Holtemme stream. This contribution impacts nitrate loads and nitrate isotopic signatures depending on the prevailing hydrological conditions. Nitrogen isotopic signatures in the catchment are mainly controlled by different sources (nitrified soil nitrogen in the headwater and manure/ effluents from WWTPs in the lowlands) and increase with raising nitrate concentrations along the main river. Nitrate loads at the outlet of the catchment are extremely different between both sampling campaigns (2014: NO3- = 97 t a-1, 2015: NO3- = 5 t a-1) which is associated with various runoff (2014: 0.8 m3 s-1, 2015: 0.2 m3 s-1). In 2015, the inflow from WWTP's raises the NO3- loads and enriches δ18O-NO3 values. Generally, oxygen isotope signatures from nitrate are more variable and are controlled by biogeochemical processes in concert with the oxygen isotopic composition of the ambient water. Elevated δ18O-NO3 in 2015 are most likely due to higher temperatures and lower

Comparison of five organic wastes regarding their behaviour during composting: Part 2, nitrogen dynamic

International Nuclear Information System (INIS)

Guardia, A. de; Mallard, P.; Teglia, C.; Marin, A.; Le Pape, C.; Launay, M.; Benoist, J.C.; Petiot, C.

2010-01-01

This paper aimed to compare household waste, separated pig solids, food waste, pig slaughterhouse sludge and green algae regarding processes ruling nitrogen dynamic during composting. For each waste, three composting simulations were performed in parallel in three similar reactors (300 L), each one under a constant aeration rate. The aeration flows applied were comprised between 100 and 1100 L/h. The initial waste and the compost were characterized through the measurements of their contents in dry matter, total carbon, Kjeldahl and total ammoniacal nitrogen, nitrite and nitrate. Kjeldahl and total ammoniacal nitrogen and nitrite and nitrate were measured in leachates and in condensates too. Ammonia and nitrous oxide emissions were monitored in continue. The cumulated emissions in ammonia and in nitrous oxide were given for each waste and at each aeration rate. The paper focused on process of ammonification and on transformations and transfer of total ammoniacal nitrogen. The parameters of nitrous oxide emissions were not investigated. The removal rate of total Kjeldahl nitrogen was shown being closely tied to the ammonification rate. Ammonification was modelled thanks to the calculation of the ratio of biodegradable carbon to organic nitrogen content of the biodegradable fraction. The wastes were shown to differ significantly regarding their ammonification ability. Nitrogen balances were calculated by subtracting nitrogen losses from nitrogen removed from material. Defaults in nitrogen balances were assumed to correspond to conversion of nitrate even nitrite into molecular nitrogen and then to the previous conversion by nitrification of total ammoniacal nitrogen. The pool of total ammoniacal nitrogen, i.e. total ammoniacal nitrogen initially contained in waste plus total ammoniacal nitrogen released by ammonification, was calculated for each experiment. Then, this pool was used as the referring amount in the calculation of the rates of accumulation, stripping and

Biochemical, Physiological and Transcriptomic Comparison between Burley and Flue-Cured Tobacco Seedlings in Relation to Carbohydrates and Nitrate Content

Directory of Open Access Journals (Sweden)

Yafei Li

2017-12-01

Full Text Available Burley tobacco is a genotype of chloroplast-deficient mutant with accumulates high levels of tobacco-specific nitrosamines (TSNAs which would induce malignant tumors in animals. Nitrate is a principle precursor of tobacco-specific nitrosamines. Nitrate content in burley tobacco was significantly higher than that in flue-cured tobacco. The present study investigated differences between the two tobacco types to explore the mechanisms of nitrate accumulation in burley tobacco. transcripts (3079 related to the nitrogen and carbon metabolism were observed. Expression of genes involved in carbon fixation, glucose and starch biosynthesis, nitrate translocation and assimilation were significantly low in burley tobacco than flue-cured tobacco. Being relative to flue-cured tobacco, burley tobacco was significantly lower at total nitrogen and carbohydrate content, nitrate reductase and glutamine synthetase activities, chlorophyll content and photosynthetic rate (Pn, but higher nitrate content. Burley tobacco required six-fold more nitrogen fertilizers than flue-cured tobacco, but both tobaccos had a similar leaf biomass. Reduced chlorophyll content and photosynthetic rate (Pn might result in low carbohydrate formation, and low capacity of nitrogen assimilation and translocation might lead to nitrate accumulation in burley tobacco.

Year-round atmospheric wet and dry deposition of nitrogen and phosphorus on water and land surfaces in Nanjing, China.

Science.gov (United States)

Sun, Liying; Li, Bo; Ma, Yuchun; Wang, Jinyang; Xiong, Zhengqin

2013-06-01

The dry deposition of ammonium, nitrate, and total phosphorus (TP) to both water (DW) and land (DD) surfaces, along with wet deposition, were simultaneously monitored from March 2009 to February 2011 in Nanjing, China. Results showed that wet deposition of total phosphorus was 1.1 kg phosphorus ha (-1)yr(-1), and inorganic nitrogen was 28.7 kg nitrogen ha (-1)yr(-1), with 43% being ammonium nitrogen. Dry deposition of ammonium, nitrate, and total phosphorus, measured by the DW/DD method, was 7.5/2.2 kg nitrogen ha (-1)yr(-1), 6.3/ 4.9 kg nitrogen ha (-1)yr(-1), and 1.9/0.4 kg phosphorus ha (-1)yr(-1), respectively. Significant differences between the DW and DD methods indicated that both methods should be employed simultaneously when analyzing deposition to aquatic and terrestrial ecosystems in watershed areas. The dry deposition of ammonium, nitrate, and total phosphorus contributed 38%, 28%, and 63%, respectively, to the total deposition in the simulated aquatic ecosystem; this has significance for the field of water eutrophication control.

Highly functionalized organic nitrates in the southeast United States: Contribution to secondary organic aerosol and reactive nitrogen budgets

Energy Technology Data Exchange (ETDEWEB)

Lee, Ben H.; Mohr, Claudia; Lopez-Hilfiker, Felipe D.; Lutz, Anna; Hallquist, Mattias; Lee, Lance; Romer, Paul; Cohen, Ronald C.; Iyer, Siddharth; Kurtén, Theo; Hu, Weiwei; Day, Douglas A.; Campuzano-Jost, Pedro; Jimenez, Jose L.; Xu, Lu; Ng, Nga Lee; Guo, Hongyu; Weber, Rodney J.; Wild, Robert J.; Brown, Steven S.; Koss, Abigail; de Gouw, Joost; Olson, Kevin; Goldstein, Allen H.; Seco, Roger; Kim, Saewung; McAvey, Kevin; Shepson, Paul B.; Starn, Tim; Baumann, Karsten; Edgerton, Eric S.; Liu, Jiumeng; Shilling, John E.; Miller, David O.; Brune, William; Schobesberger, Siegfried; D' Ambro, Emma L.; Thornton, Joel A.

2016-01-25

Organic nitrates (ON = RONO2 + RO2NO2) are an important reservoir, if not sink, of atmospheric nitrogen oxides (NOx=NO+NO2). ON formed from isoprene oxidation alone are responsible for the export of 8 to 30% of anthropogenic NOx out of the U.S. continental boundary layer [Horowitz et al., 1998; Liang et al., 1998]. Regional NOx budgets and tropospheric ozone (O3) production, are therefore particularly sensitive to uncertainties in the yields and fates of ON [Beaver et al., 2012; Browne et al., 2013]. The yields implemented in modeling studies are determined from laboratory experiments in which only a few of the first generation gaseous ON or the total gas and particle-phase ON have been quantified [Perring et al., 2013 and references therein], while production of highly functionalized ON capable of strongly partitioning to the particle-phase have been inferred [Farmer et al., 2010; Ng et al., 2007; Nguyen et al., 2011; Perraud et al., 2012; Rollins et al., 2012], or directly measured [Ehn et al., 2014]. Addition of a nitrate (–ONO2) functional group to a hydrocarbon is estimated to lower the equilibrium saturation vapor pressure by 2.5 to 3 orders of magnitude [e.g. Capouet and Muller, 2006]. Thus, organic nitrate formation can potentially enhance particle-phase partitioning of hydrocarbons in regions with elevated levels of nitrogen oxides, contributing to secondary organic aerosol (SOA) formation [Ng et al., 2007]. There has, however, been no high time-resolved measurements of speciated ON in the particle-phase. We utilize a newly developed high-resolution time-of-flight chemical ionization mass spectrometer (HR-ToF-CIMS) using Iodide-adduct ionization [B H Lee et al., 2014a] with a filter inlet for gases and aerosols (FIGAERO) [Lopez-Hilfiker et al., 2014] that allows alternating in situ measurement of the molecular composition of gas and particle phases. We present observations of speciated ON in the particle-phase obtained during the 2013 Southern Oxidant

Comparison of nitrate accumulation, nitrogen uptake and utilization efficiency among different spinach (Spinacia oleracea L. genotypes

Directory of Open Access Journals (Sweden)

Zhou Jianjian

2017-10-01

Full Text Available A hydroponic experiment was conducted to study the difference of nitrate accumulation,nitrogen uptake and utilization efficiency between four spinach (Spinacia oleracea L. genotypes (So10,So13,So18 and So57. Results showed that So13 had the highest nitrate contents under two nitrate (NO3--N level (0.5 mmol·L-1,15 mmol·L-1 conditions,whereas So10 had the lowest nitrate contents. So18 had the similar nitrate contents with So13 under low NO3- level,while it showed no significant difference of nitrate contents with So57 under high NO3- treatment. The 15NO3--N uptake rates of So13 were the highest one among four genotypes,while the N utilization efficiency (NutE and N utilization ratio (NUR of So13 were significantly lower than those of So18 and So57. The shoot dry mass,nitrate reductase activity,NutE,NUR of So18 and So57 were higher than those of So13 and So10,while their 15NO3--N uptake rates were lower than those of So13. The shoot dry mass,nitrate reductase activity,NutE,N utilization ratio of So10 were significantly lower than those of So18 and So57,and its 15NO3--N uptake rate was significantly lower than those of So13. Among the four spinach genotypes,the So57 can be selected as elite germplasm using for spinach production for its relatively lower nitrate content and higher N efficiency.

Estimating soil solution nitrate concentration from dielectric spectra using PLS analysis

Science.gov (United States)

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...

Application of thermal-dissociation laser induced fluorescence (TD-LIF to measurement of HNO3, Σalkyl nitrates, Σperoxy nitrates, and NO2 fluxes using eddy covariance

Directory of Open Access Journals (Sweden)

D. K. Farmer

2006-01-01

Full Text Available Nitrogen exchange between the atmosphere and biosphere directly influences atmospheric composition. While much is known about mechanisms of NO and N2O emissions, instrumentation for the study of mechanisms contributing to exchange of other major nitrogen species is quite limited. Here we describe the application of a new technique, thermal dissociation-laser induced fluorescence (TD-LIF, to eddy covariance measurements of the fluxes of NO2, total peroxy acyl and peroxy nitrates, total alkyl and multifunctional alkyl nitrates, and nitric acid. The technique offers the potential for investigating mechanisms of exchange of these species at the canopy scale over timescales from days to years. Examples of flux measurements at a ponderosa pine plantation in the mid-elevation Sierra Nevada Mountains in California are reported and used to evaluate instrument performance.

GROWTH AND COMPOSITION OF Arthrospira (Spirulina platensis IN A TUBULAR PHOTOBIOREACTOR USING AMMONIUM NITRATE AS THE NITROGEN SOURCE IN A FED-BATCH PROCESS

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C. Cruz-Martínez

2015-06-01

Full Text Available AbstractNH4NO3 simultaneously provides a readily assimilable nitrogen source (ammonia and a reserve of nitrogen (nitrate, allowing for an increase in Arthrospira platensis biomass production while reducing the cost of the cultivation medium. In this study, a 22plus star central composite experimental design combined with response surface methodology was employed to analyze the influence of light intensity (I and the total amount of added NH4NO3 (Mt on a bench-scale tubular photobioreactor for fed-batch cultures. The maximum cell concentration (Xm, cell productivity (PX and biomass yield on nitrogen (YX/N were evaluated, as were the protein and lipid contents. Under optimized conditions (I = 148 μmol·photons·m-2·s-1 and Mt = 9.7 mM NH4NO3, Xm = 4710 ±34.4 mg·L-1, PX = 478.9 ±3.8 mg·L-1·d-1 and YX/N = 15.87 ±0.13 mg·mg-1 were obtained. The best conditions for protein content in the biomass (63.2% were not the same as those that maximized cell growth (I = 180 μmol·photons·m-2·s-1 and Mt = 22.5 mM NH4NO3. Based on these results, it is possible to conclude that ammonium nitrate is an interesting alternate nitrogen source for the cultivation of A. platensisin a fed-batch process and could be used for other photosynthetic microorganisms.

Molecular nitrogen fixation and nitrogen cycle in nature

Energy Technology Data Exchange (ETDEWEB)

Virtanen, A I

1952-01-01

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

Efficient electrochemical reduction of nitrate to nitrogen using Ti/IrO2-Pt anode and different cathodes

International Nuclear Information System (INIS)

Li Miao; Feng Chuanping; Zhang Zhenya; Sugiura, Norio

2009-01-01

Electrochemical reduction of nitrate using Fe, Cu, and Ti as cathodes and Ti/IrO 2 -Pt as anode in an undivided and unbuffered cell was studied. In the presence of appropriate amount of NaCl, both cathodic reduction of nitrate and anodic oxidation of the by-products of ammonia and nitrite were achieved by all cathodes under a proper condition. Both in the absence and presence of NaCl, the order of nitrate removal rate was Fe > Cu > Ti. The nitrate removal was 87% and selectivity to nitrogen was 100% in 3 h with Fe cathode in the presence of NaCl. Ti/IrO 2 -Pt anode played an important role during nitrate reduction, especially in the presence of NaCl, at which by-products could efficiently be oxidized. Moreover, atomic force microscopy (AFM) investigation shown Ti/IrO 2 -Pt anode was suitable for nitration reduction and the surface roughness of all cathodes increased. The concentrations of Fe, Cu, and Ti in the electrolyte were less than 0.15, 0.12 and 0.09 mg/L after 3 h electrolysis, respectively.

Enhancing Nitrogen Availability, Ammonium Adsorption-Desorption, and Soil pH Buffering Capacity using Composted Paddy Husk

Science.gov (United States)

Latifah, O.; Ahmed, O. H.; Abdul Majid, N. M.

2017-12-01

Form of nitrogen present in soils is one of the factors that affect nitrogen loss. Nitrate is mobile in soils because it does not absorb on soil colloids, thus, causing it to be leached by rainfall to deeper soil layers or into the ground water. On the other hand, temporary retention and timely release of ammonium in soils regulate nitrogen availability for crops. In this study, composted paddy husk was used in studies of soil leaching, buffering capacity, and ammonium adsorption and desorption to determine the: (i) availability of exchangeable ammonium, available nitrate, and total nitrogen in an acid soil after leaching the soil for 30 days, (ii) soil buffering capacity, and (iii) ability of the composted paddy husk to adsorb and desorb ammonium from urea. Leaching of ammonium and nitrate were lower in all treatments with urea and composted paddy husk compared with urea alone. Higher retention of soil exchangeable ammonium, available nitrate, and total nitrogen of the soils with composted paddy husk were due to the high buffering capacity and cation exchange capacity of the amendment to adsorb ammonium thus, improving nitrogen availability through temporary retention on the exchange sites of the humic acids of the composted paddy husk. Nitrogen availability can be enhanced if urea is amended with composted paddy husk.

Nitrogen-15 studies on identifying fertilizer excess in environmental systems

International Nuclear Information System (INIS)

Freyer, H.D.; Aly, A.I.M.

1975-01-01

The feasibility of identifying fertilizer excesses in surface and ground waters on the basis of variations in the isotope ratio of nitrogen has been studied. The isotope ratio of the commonly used ammonium and nitrate fertilizers is similar to that of atmospheric nitrogen. These ratios are shifted when fertilizers are added to the soil. In the soil, fertilizer ammonium is oxidized and the nitrate formed is reduced in the heavy isotope. The fractionation factors are calculated. This artificially added nitrate becomes mixed with natural nitrate which, in general, is enriched in the heavy isotope. Only 50% (or even less) of the nitrate formed may stem from the added fertilizer. The mixing ratios are time-dependent, and different for various types and conditions of soil. In spite of this complexity, information on this isotopic process should be obtainable, if the isotope ratios of artificial and natural nitrate, respectively, are substantially different. Surface waters, in general, show no significant correlation between nitrate content and isotope ratio due to additions of sewage waters. Some data on ground waters from agricultural areas, however, where the nitrate content apparently resulted from fertilizers, gave a negative correlation of lower isotope ratios with higher nitrate contents. An inverse correlation was found in the isotope ratios of nitrate in untouched surface waters, and they even reflect the composition of the total soil nitrogen. (author)

Estimating ammonium and nitrate load from septic systems to surface water bodies within ArcGIS environments

Science.gov (United States)

Zhu, Yan; Ye, Ming; Roeder, Eberhard; Hicks, Richard W.; Shi, Liangsheng; Yang, Jinzhong

2016-01-01

This paper presents a recently developed software, ArcGIS-based Nitrogen Load Estimation Toolkit (ArcNLET), for estimating nitrogen loading from septic systems to surface water bodies. The load estimation is important for managing nitrogen pollution, a world-wide challenge to water resources and environmental management. ArcNLET simulates coupled transport of ammonium and nitrate in both vadose zone and groundwater. This is a unique feature that cannot be found in other ArcGIS-based software for nitrogen modeling. ArcNLET is designed to be flexible for the following four simulating scenarios: (1) nitrate transport alone in groundwater; (2) ammonium and nitrate transport in groundwater; (3) ammonium and nitrate transport in vadose zone; and (4) ammonium and nitrate transport in both vadose zone and groundwater. With this flexibility, ArcNLET can be used as an efficient screening tool in a wide range of management projects related to nitrogen pollution. From the modeling perspective, this paper shows that in areas with high water table (e.g. river and lake shores), it may not be correct to assume a completed nitrification process that converts all ammonium to nitrate in the vadose zone, because observation data can indicate that substantial amount of ammonium enters groundwater. Therefore, in areas with high water table, simulating ammonium transport and estimating ammonium loading, in addition to nitrate transport and loading, are important for avoiding underestimation of nitrogen loading. This is demonstrated in the Eggleston Heights neighborhood in the City of Jacksonville, FL, USA, where monitoring well observations included a well with predominant ammonium concentrations. The ammonium loading given by the calibrated ArcNLET model can be 10-18% of the total nitrogen load, depending on various factors discussed in the paper.

Evaluation of hydrologic conditions and nitrate concentrations in the Rio Nigua de Salinas alluvial fan aquifer, Salinas, Puerto Rico, 2002-03

Science.gov (United States)

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

The effect of spatial heterogeneity on nitrate reduction in soil systems

DEFF Research Database (Denmark)

Pedersen, Lasse Lu

the initial inoculum size, nitrate reduction was barely affected, but DNRA increased substantially by 71%. Additionally, nitrite-, ammonium-, and nitrous oxide were sequentially produced during nitrate reduction: an initial burst of nitrite production led to DNRA, and for the microcosms which became mass...... was chemically or biochemically fixed from inert nitrogen, back into the atmosphere as inert nitrogen. Over the last century, the excess of anthropogenically fixed nitrogen has put increasing pressures on the nitrogen cycle. Nitrate is a central molecule in the nitrogen cycle. Its concentration is, on the one...... hand governed by formation by oxidation of ammonia-N, and on the other hand by removal a removal by two dissimilatory nitrate reduction processes:denitrification, in which nitrate is converted to the gaseous compounds dinitrogen and nitrous oxide, and dissimilatory nitrate reduction to ammonium, DNRA...

Assessing the relationship between groundwater nitrate and animal feeding operations in Iowa (USA)

Science.gov (United States)

Zirkle, Keith W.; Nolan, Bernard T.; Jones, Rena R.; Weyer, Peter J.; Ward, Mary H.; Wheeler, David C.

2016-01-01

Nitrate-nitrogen is a common contaminant of drinking water in many agricultural areas of the United States of America (USA). Ingested nitrate from contaminated drinking water has been linked to an increased risk of several cancers, specific birth defects, and other diseases. In this research, we assessed the relationship between animal feeding operations (AFOs) and groundwater nitrate in private wells in Iowa. We characterized AFOs by swine and total animal units and type (open, confined, or mixed), and we evaluated the number and spatial intensities of AFOs in proximity to private wells. The types of AFO indicate the extent to which a facility is enclosed by a roof. Using linear regression models, we found significant positive associations between the total number of AFOs within 2 km of a well (p trend nitrate concentration. Additionally, we found significant increases in log nitrate in the top quartiles for AFO spatial intensity, open AFO spatial intensity, and mixed AFO spatial intensity compared to the bottom quartile (0.171 log(mg/L), 0.319 log(mg/L), and 0.541 log(mg/L), respectively; all p nitrate-nitrogen in drinking wells and found significant spatial clustering of high-nitrate wells (> 5 mg/L) compared with low-nitrate (≤ 5 mg/L) wells (p = 0.001). A generalized additive model for high-nitrate status identified statistically significant areas of risk for high levels of nitrate. Adjustment for some AFO predictor variables explained a portion of the elevated nitrate risk. These results support a relationship between animal feeding operations and groundwater nitrate concentrations and differences in nitrate loss from confined AFOs vs. open or mixed types.

[Effects of controlled release blend bulk urea on soil nitrogen and soil enzyme activity in wheat and rice fields].

Science.gov (United States)

Zhang, Jing Sheng; Wang, Chang Quan; Li, Bing; Liang, Jing Yue; He, Jie; Xiang, Hao; Yin, Bin; Luo, Jing

2017-06-18

A field experiment was conducted to investigate the effect of controlled-release fertilizer (CRF) combined with urea (UR) on the soil fertility and environment in wheat-rice rotation system. Changes in four forms of nitrogen (total nitrogen, ammonium nitrogen, nitrate nitrogen, and microbial biomass nitrogen) and in activities of three soil enzymes participating in nitrogen transformation (urease, protease, and nitrate reductase) were measured in seven fertilization treatments (no fertilization, routine fertilization, 10%CRF+90%UR, 20%CRF+80%UR, 40%CRF+60%UR, 80%CRF+20%UR, and 100%CRF). The results showed that soil total nitrogen was stable in the whole growth period of wheat and rice. There was no significant difference among the treatments of over 20% CRF in soil total nitrogen content of wheat and rice. The soil inorganic nitrogen content was increased dramatically in treatments of 40% or above CRF during the mid-late growing stages of wheat and rice. With the advance of the growth period, conventional fertilization significantly decreased soil microbial biomass nitrogen, but the treatments of 40% and above CRF increased the soil microbial biomass nitrogen significantly. The soil enzyme activities were increased with over 40% of CRF in the mid-late growing stage of wheat and rice. By increasing the CRF ratio, the soil protease activity and nitrate reductase activity were improved gradually, and peaked in 100% CRF. The treatments of above 20% CRF could decrease the urease activity in tillering stage of rice and delay the peak of ammonium nitrogen, which would benefit nitrogen loss reduction. The treatments of 40% and above CRF were beneficial to improving soil nitrogen supply and enhancing soil urease and protease activities, which could promote the effectiveness of nitrogen during the later growth stages of wheat and rice. The 100% CRF treatment improved the nitrate reductase activity significantly during the later stage of wheat and rice. Compared with the

Formation and maintenance of high-nitrate, low pH layers in the eastern Indian Ocean and the role of nitrogen fixation

Directory of Open Access Journals (Sweden)

A. M. Waite

2013-08-01

Full Text Available We investigated the biogeochemistry of low dissolved oxygen high-nitrate (LDOHN layers forming against the backdrop of several interleaving regional water masses in the eastern Indian Ocean, off northwest Australia adjacent to Ningaloo Reef. These water masses, including the forming Leeuwin Current, have been shown directly to impact the ecological function of Ningaloo Reef and other iconic coastal habitats downstream. Our results indicate that LDOHN layers are formed from multiple subduction events of the Eastern Gyral Current beneath the Leeuwin Current (LC; the LC originates from both the Indonesian Throughflow and tropical Indian Ocean. Density differences of up to 0.025 kg m−3 between the Eastern Gyral Current and the Leeuwin Current produce sharp gradients that can trap high concentrations of particles (measured as low transmission along the density interfaces. The oxidation of the trapped particulate matter results in local depletion of dissolved oxygen and regeneration of dissolved nitrate (nitrification. We document an associated increase in total dissolved carbon dioxide, which lowers the seawater pH by 0.04 units. Based on isotopic measurements (δ15N and δ18O of dissolved nitrate, we determine that ~ 40–100% of the nitrate found in LDOHN layers is likely to originate from nitrogen fixation, and that, regionally, the importance of N-fixation in contributing to LDOHN layers is likely to be highest at the surface and offshore.

Manipulation of Contents of Nitrate, Phenolic Acids, Chlorophylls, and Carotenoids in Lettuce (Lactuca sativa L.) via Contrasting Responses to Nitrogen Fertilizer When Grown in a Controlled Environment.

Science.gov (United States)

Qadir, Othman; Siervo, Mario; Seal, Chris J; Brandt, Kirsten

2017-11-22

This study aimed to use different nitrogen fertilizer regimes to produce Butterhead lettuce with such large differences in nitrate content that they could be used as treatment and placebo to study the effect of inorganic nitrate on human health. Plants were grown under controlled conditions at 27/23 °C day/night with a relatively low photosynthetically active radiation (PAR) of 150 μmol m -2 s -1 for 14 h day -1 and nitrogen supplies ranging from 26 to 154 ppm of N as ammonium nitrate in the fertigation solution. This resulted in contrasting high (∼1078 mg nitrate 100 g -1 FW) or low (∼6 mg 100 g -1 ) nitrate contents in the leaves. Contents of carotenoids and chlorophylls in fresh weight did not differ significantly between the highest and the lowest N-supply levels. However, increased nitrogen supply reduced contents of phenolic compounds from 154 to 22 mg 100 g -1 FW, dry matter content from 8.9% to 4.6%, and fresh weight per plant from 108.52 to 47.57 g/plant FW (all P < 0.001). Thus, while fertilizer treatments can provide lettuce with substantially different nitrate contents, maintaining similar pigment contents (color), they also strongly influence the contents of phenolic acids and flavones.

The effect of water stress on nitrate reductase activity and nitrogen and phosphorus contents in cuminum cyminum l

Energy Technology Data Exchange (ETDEWEB)

Sepehr, M F [Islamic Azad University, Saveh (Iran, Islamic Republic of). Dept. of Biology; Amini, F [Tehran Shomal Branch Islamic Azad University, Tehran (Iran, Islamic Republic of). Dept. of Biology

2012-06-15

Cumin (Cuminum cyminum L.) is a plant with great medicinal importance cultivated in many regions such as Iran, India, Indonesia, Afghanistan, Pakistan, Lebanon, Syria and Turkey. In this research, nitrogen and phosphorus concentrations and nitrate reductase enzyme activity were studied in cumin under flooding stress. Cumin plants were cultivated in pots containing garden soil (in 1 cm depth, 15 -20 degree C, 14 h light and 10 h darkness). Germination took place after 2 weeks. Flooding stress was applied 6 weeks after germination on a number of pots according to their field capacity (FC) (2, 3, and 4 fold) for 1 week; a number of pots were also considered as controls with field capacity. Plants were then harvested and chemical analysis of the factors under study was done using roots and shoots of the plants exposed to flooding conditions and the control plants. The experiment had a completely randomized design in which four levels of water in the soil (2FC, 3FC, 4FC) were compared. Analysis of variance was carried out using SPSS software and means were compared by Duncan's test at [ greater or equal to = 0.05 significance level. The results showed that in comparison with control plants, nitrogen and phosphorus concentrations were significantly lower in both shoots and roots of flooded plants. This decrease was more pronounced in treated plants exposed to 4 X field capacity conditions. Nitrogen concentration in roots and shoots of treated plants showed a significant decrease in comparison with control plants and this was more noticeable in treated plants exposed to 4 X field capacity conditions. Moreover, concentration of nitrite produced from nitrate reduction catalyzed by nitrate reductase enzyme in roots and shoots of treated plants had a significant increase in comparison with control plants. Treated plants exposed to 4 X field capacity conditions showed the most increase. Also the study showed that cumin seeds could survive in flooding environment for 14 days

The effect of water stress on nitrate reductase activity and nitrogen and phosphorus contents in cuminum cyminum l

International Nuclear Information System (INIS)

Sepehr, M.F.; Amini, F.

2012-01-01

Cumin (Cuminum cyminum L.) is a plant with great medicinal importance cultivated in many regions such as Iran, India, Indonesia, Afghanistan, Pakistan, Lebanon, Syria and Turkey. In this research, nitrogen and phosphorus concentrations and nitrate reductase enzyme activity were studied in cumin under flooding stress. Cumin plants were cultivated in pots containing garden soil (in 1 cm depth, 15 -20 degree C, 14 h light and 10 h darkness). Germination took place after 2 weeks. Flooding stress was applied 6 weeks after germination on a number of pots according to their field capacity (FC) (2, 3, and 4 fold) for 1 week; a number of pots were also considered as controls with field capacity. Plants were then harvested and chemical analysis of the factors under study was done using roots and shoots of the plants exposed to flooding conditions and the control plants. The experiment had a completely randomized design in which four levels of water in the soil (2FC, 3FC, 4FC) were compared. Analysis of variance was carried out using SPSS software and means were compared by Duncan's test at [ greater or equal to = 0.05 significance level. The results showed that in comparison with control plants, nitrogen and phosphorus concentrations were significantly lower in both shoots and roots of flooded plants. This decrease was more pronounced in treated plants exposed to 4 X field capacity conditions. Nitrogen concentration in roots and shoots of treated plants showed a significant decrease in comparison with control plants and this was more noticeable in treated plants exposed to 4 X field capacity conditions. Moreover, concentration of nitrite produced from nitrate reduction catalyzed by nitrate reductase enzyme in roots and shoots of treated plants had a significant increase in comparison with control plants. Treated plants exposed to 4 X field capacity conditions showed the most increase. Also the study showed that cumin seeds could survive in flooding environment for 14 days

Evaluation of wastewater nitrogen transformation in a natural wetland (Ulaanbaatar, Mongolia) using dual-isotope analysis of nitrate

International Nuclear Information System (INIS)

Itoh, Masayuki; Takemon, Yasuhiro; Makabe, Akiko; Yoshimizu, Chikage; Kohzu, Ayato; Ohte, Nobuhito; Tumurskh, Dashzeveg; Tayasu, Ichiro; Yoshida, Naohiro; Nagata, Toshi

2011-01-01

The Tuul River, which provides water for the daily needs of many residents of Ulaanbaatar, Mongolia, has been increasingly polluted by wastewater from the city's sewage treatment plant. Information on water movement and the transformation of water-borne materials is required to alleviate the deterioration of water quality. We conducted a synoptic survey of general water movement, water quality including inorganic nitrogen concentrations, and isotopic composition of nitrogen (δ 15 N-NO 3 - , δ 18 O-NO 3 - , and δ 15 N-NH 4 + ) and water (δ 18 O-H 2 O) in a wetland area that receives wastewater before it enters the Tuul River. We sampled surface water, groundwater, and spring water along the two major water routes in the wetland that flow from the drain of the sewage treatment plant to the Tuul River: a continuous tributary and a discontinuous tributary. The continuous tributary had high ammonium (NH 4 + ) concentrations and nearly stable δ 15 N-NH 4 + , δ 15 N-NO 3 - , and δ 18 O-NO 3 - concentrations throughout its length, indicating that nitrogen transformation (i.e., nitrification and denitrification) during transit was small. In contrast, NH 4 + concentrations decreased along the discontinuous tributary and nitrate (NO 3 - ) concentrations were low at many points. Values of δ 15 N-NH 4 + , δ 15 N-NO 3 - , and δ 18 O-NO 3 - increased with flow along the discontinuous route. Our results indicate that nitrification and denitrification contribute to nitrogen removal in the wetland area along the discontinuous tributary with slow water transport. Differences in hydrological pathways and the velocity of wastewater transport through the wetland area greatly affect the extent of nitrogen removal. - Research Highlights: → Dual-isotope analysis of nitrate was used to assess wastewater nitrogen status. → Wetland that receives the wastewater contributed to nitrogen removal. → Differences in hydrological pathways greatly affect the extent of nitrogen removal.

Nitrate storage and dissimilatory nitrate reduction by eukaryotic microbes

DEFF Research Database (Denmark)

Kamp, Anja; Høgslund, Signe; Risgaard-Petersen, Nils

2015-01-01

The microbial nitrogen cycle is one of the most complex and environmentally important element cycles on Earth and has long been thought to be mediated exclusively by prokaryotic microbes. Rather recently, it was discovered that certain eukaryotic microbes are able to store nitrate intracellularly......, suggesting that eukaryotes may rival prokaryotes in terms of dissimilatory nitrate reduction. Finally, this review article sketches some evolutionary perspectives of eukaryotic nitrate metabolism and identifies open questions that need to be addressed in future investigations....... and use it for dissimilatory nitrate reduction in the absence of oxygen. The paradigm shift that this entailed is ecologically significant because the eukaryotes in question comprise global players like diatoms, foraminifers, and fungi. This review article provides an unprecedented overview of nitrate...

Nitrogen-limited mangrove ecosystems conserve N through dissimilatory nitrate reduction to ammonium.

Science.gov (United States)

Fernandes, Sheryl Oliveira; Bonin, Patricia C; Michotey, Valérie D; Garcia, Nicole; LokaBharathi, P A

2012-01-01

Earlier observations in mangrove sediments of Goa, India have shown denitrification to be a major pathway for N loss. However, percentage of total nitrate transformed through complete denitrification accounted for nitrate reduced. Here, we show that up to 99% of nitrate removal in mangrove sediments is routed through dissimilatory nitrate reduction to ammonium (DNRA). The DNRA process was 2x higher at the relatively pristine site Tuvem compared to the anthropogenically-influenced Divar mangrove ecosystem. In systems receiving low extraneous nutrient inputs, this mechanism effectively conserves and re-circulates N minimizing nutrient loss that would otherwise occur through denitrification. In a global context, the occurrence of DNRA in mangroves has important implications for maintaining N levels and sustaining ecosystem productivity. For the first time, this study also highlights the significance of DNRA in buffering the climate by modulating the production of the greenhouse gas nitrous oxide.

Nitrate contamination of groundwater and its countermeasures

Energy Technology Data Exchange (ETDEWEB)

Mitamura, Hisayoshi [Japan Atomic Energy Research Inst., Tokai, Ibaraki (Japan). Tokai Research Establishment

2003-03-01

The inevitable increases of food production and energy consumption with an increase in world population become main causes of an increase of nitrate load to the environment. Although nitrogen is essential for the growth of animal and plant as a constituent element of protein, excessive nitrate load to the environment contaminates groundwater resources used as drinking water and leads to seriously adverse effects on the health of man and livestock. In order to clarify the problem of nitrate contamination of groundwater and search a new trend of technology development from the viewpoint of environment remediation and protection, the present paper has reviewed adverse effects of nitrate on human health, the actual state of nitrogen cycle, several kinds of nitrate sources, measures for reducing nitrate level, etc. (author)

Tracing nitrate-nitrogen sources and modifications in a stream impacted by various land uses, South Portugal

NARCIS (Netherlands)

Yevenes, M.A.; Soetaert, K.; Mannaerts, C.M.

2016-01-01

The identification of nitrate-nitrogen (NO3-N) origin is important in the control of surface and ground water quality. These are the main sources of available drinking water. Stable isotopes (15N and 18O) for NO3-N and along with a 1-D reactive transport model were used to study the origin and

Tracing Nitrate-Nitrogen Sources and Modifications in a Stream Impacted by Various Land Uses, South Portugal

NARCIS (Netherlands)

Yevenes, M.A.; Soetaert, K.; Mannaerts, C.M.

2016-01-01

The identification of nitrate-nitrogen (NO3–N) origin is important in the control of surfaceand ground water quality. These are the main sources of available drinking water. Stable isotopes(15N and 18O) for NO3–N and along with a 1-D reactive transport model were used to study the originand

Nitrate concentration in spring water at the Nogawa basin and its possible source

International Nuclear Information System (INIS)

Yoshida, Kazuhiro; Ogura, Norio

1978-01-01

Fluctuation of nitrate concentration in spring water at the Nogawa basin was studied during 1976 - 1977, and the possible source of nitrate nitrogen was discussed. Nitrate concentration in spring water at the station N-O in Kokubunji, Tokyo ranged from 360 to 574 μg at/l with an average value of 502 μg at/l. It seemed that the effluent of spring water at N-O was influenced by rainfall within a short period. A laboratory experiment on production of nitrate in soil showed that ammonium nitrogen added to fresh soil was transformed quantitatively to nitrate nitrogen during 23 days incubation. Thd sup(delta15)N value of nitrate nitrogen in spring water (+0.89%) was similar to that of ammonium nitrogen in sewage (+0.82%) discharging into the Nogawa River. In the area near N-O, domestic wastes have been discharged into the Nogawa River by simple sewers or percolated downward through the soil. These results suggest that one of the main source of nitrate nitrogen in spring water is ammonium and organic nitrogen in domestic wastes. (author)

Protein Losses and Urea Nitrogen Underestimate Total Nitrogen Losses in Peritoneal Dialysis and Hemodialysis Patients.

Science.gov (United States)

Salame, Clara; Eaton, Simon; Grimble, George; Davenport, Andrew

2018-04-28

Muscle wasting is associated with increased mortality and is commonly reported in dialysis patients. Hemodialysis (HD) and peritoneal dialysis (PD) treatments lead to protein losses in effluent dialysate. We wished to determine whether changes in current dialysis practice had increased therapy-associated nitrogen losses. Cross-sectional cohort study. Measurement of total protein, urea and total nitrogen in effluent dialysate from 24-hour collections from PD patients, and during haemodiafiltration (HDF) and haemodialysis (HD) sessions. One hundred eight adult dialysis patients. Peritoneal dialysis, high-flux haemodialysis and haemodiafiltration. Total nitrogen and protein losses. Dialysate protein losses were measured in 68 PD and 40 HD patients. Sessional losses of urea (13.9 [9.2-21.1] vs. 4.8 [2.8-7.8] g); protein (8.6 [7.2-11.1] vs. 6.7 [3.9-11.1] g); and nitrogen (11.5 [8.7-17.7] vs. 4.9 [2.6-9.5] g) were all greater for HD than PD, P losses were lower with HD 25.9 (21.5-33.4) versus 46.6 (27-77.6) g/week, but nitrogen losses were similar. We found no difference between high-flux HD and HDF: urea (13.5 [8.8-20.6] vs. 15.3 [10.5-25.5] g); protein (8.8 [7.3-12.2] vs. 7.6 [5.8-9.0] g); and total nitrogen (11.6 [8.3-17.3] vs. 10.8 [8.9-22.5] g). Urea nitrogen (UN) only accounted for 45.1 (38.3-51.0)% PD and 63.0 (55.3-62.4)% HD of total nitrogen losses. Although sessional losses of protein and UN were greater with HD, weekly losses were similar between modalities. We found no differences between HD and HDF. However, total nitrogen losses were much greater than the combination of protein and UN, suggesting greater nutritional losses with dialysis than previously reported. Copyright © 2018 National Kidney Foundation, Inc. Published by Elsevier Inc. All rights reserved.

Nitrogen concentrations and loads for the Connecticut River at Middle Haddam, Connecticut, computed with the use of autosampling and continuous measurements of water quality for water years 2009 to 2014

Science.gov (United States)

Mullaney, John R.; Martin, Joseph W.; Morrison, Jonathan

2018-03-20

The daily and annual loads of nitrate plus nitrite and total nitrogen for the Connecticut River at Middle Haddam, Connecticut, were determined for water years 2009 to 2014. The analysis was done with a combination of methods, which included a predefined rating curve method for nitrate plus nitrite and total nitrogen for water years 2009 to 2011 and a custom rating curve method that included sensor measurements of nitrate plus nitrite nitrogen concentration and turbidity along with mean daily flow to determine total nitrogen loads for water years 2011 to 2014. Instantaneous concentrations of total nitrogen were estimated through the use of a regression model based on sensor measurements at 15-minute intervals of nitrate plus nitrite nitrogen and turbidity for water years 2011 to 2014.Annual total nitrogen loads at the Connecticut River at Middle Haddam ranged from 12,900 to 19,200 metric tons, of which about 42 to 49 percent was in the form of nitrate plus nitrite. The mean 95-percent prediction intervals on daily total nitrogen load estimates were smaller from the custom model, which used sensor data, than those calculated by the predefined model.Annual total nitrogen load estimates at the Connecticut River at Middle Haddam were compared with the upstream load estimates at the Connecticut River at Thompsonville, Conn. Annual gains in total nitrogen loads between the two stations ranged from 3,430 to 6,660 metric tons. These increases between the two stations were attributed to the effects of increased urbanization and to combined annual discharges of 1,540 to 2,090 metric tons of nitrogen from 24 wastewater treatment facilities in the drainage area between the two stations. The contribution of total nitrogen from wastewater discharge between the two stations had declined substantially before the beginning of this study and accounted for from 31 to 52 percent of the gain in nitrogen load between the Thompsonville and Middle Haddam sites.

TRANC - a novel fast-response converter to measure total reactive atmospheric nitrogen

Science.gov (United States)

Marx, O.; Brümmer, C.; Ammann, C.; Wolff, V.; Freibauer, A.

2012-05-01

The input and loss of plant available nitrogen (reactive nitrogen: Nr) from/to the atmosphere can be an important factor for the productivity of ecosystems and thus for its carbon and greenhouse gas exchange. We present a novel converter for reactive nitrogen (TRANC: Total Reactive Atmospheric Nitrogen Converter), which offers the opportunity to quantify the sum of all airborne reactive nitrogen compounds (∑Nr) in high time resolution. The basic concept of the TRANC is the full conversion of all Nr to nitrogen monoxide (NO) within two reaction steps. Initially, reduced Nr compounds are being oxidised, and oxidised Nr compounds are thermally converted to lower oxidation states. Particulate Nr is being sublimated and oxidised or reduced afterwards. In a second step, remaining higher nitrogen oxides or those generated in the first step are catalytically converted to NO with carbon monoxide used as reduction gas. The converter is combined with a fast response chemiluminescence detector (CLD) for NO analysis and its performance was tested for the most relevant gaseous and particulate Nr species under both laboratory and field conditions. Recovery rates during laboratory tests for NH3 and NO2 were found to be 95 and 99%, respectively, and 97% when the two gases were combined. In-field longterm stability over an 11-month period was approved by a value of 91% for NO2. Effective conversion was also found for ammonium and nitrate containing particles. The recovery rate of total ambient Nr was tested against the sum of individual measurements of NH3, HNO3, HONO, NH4+, NO3-, and NOx using a combination of different well-established devices. The results show that the TRANC-CLD system precisely captures fluctuations in ∑Nr concentrations and also matches the sum of all individual Nr compounds measured by the different single techniques. The TRANC features a specific design with very short distance between the sample air inlet and the place where the thermal and catalytic

Open-Source Photometric System for Enzymatic Nitrate Quantification.

Science.gov (United States)

Wittbrodt, B T; Squires, D A; Walbeck, J; Campbell, E; Campbell, W H; Pearce, J M

2015-01-01

Nitrate, the most oxidized form of nitrogen, is regulated to protect people and animals from harmful levels as there is a large over abundance due to anthropogenic factors. Widespread field testing for nitrate could begin to address the nitrate pollution problem, however, the Cadmium Reduction Method, the leading certified method to detect and quantify nitrate, demands the use of a toxic heavy metal. An alternative, the recently proposed Environmental Protection Agency Nitrate Reductase Nitrate-Nitrogen Analysis Method, eliminates this problem but requires an expensive proprietary spectrophotometer. The development of an inexpensive portable, handheld photometer will greatly expedite field nitrate analysis to combat pollution. To accomplish this goal, a methodology for the design, development, and technical validation of an improved open-source water testing platform capable of performing Nitrate Reductase Nitrate-Nitrogen Analysis Method. This approach is evaluated for its potential to i) eliminate the need for toxic chemicals in water testing for nitrate and nitrite, ii) reduce the cost of equipment to perform this method for measurement for water quality, and iii) make the method easier to carryout in the field. The device is able to perform as well as commercial proprietary systems for less than 15% of the cost for materials. This allows for greater access to the technology and the new, safer nitrate testing technique.

Effects of coal combustion byproduct encapsulated ammonium nitrate on wheat yield and uptake of nitrogen and metals

Science.gov (United States)

Nitrogen is an essential plant nutrient that is taken up in large quantity. Ammonium nitrate (AN) is used in agriculture as an N fertilizer, but it is also an ingredient in explosives. As a result of the bombing of the Alfred P. Murrah Federal Building in Oklahoma City in April 1995, regulations o...

[Effect of NH4(+) -N/NO3(-)-N ratio in applied supplementary fertilizer on nitrogen metabolism and main chemical composition of Pinellia ternata].

Science.gov (United States)

Hu, Long-Jiao; Wang, Kang-Cai; Li, Can-Wen

2013-07-01

To study the effect of nitrogen forms on nitrogen metabolism and main chemical composition of Pinellia ternate. Through the soilless cultivation experiment and based at the same nitrogen level and different NH4(+) -N/NO3(-) -N ratios, nitrate reductase (NR) activity, glutamine synthetase (GS) activity, the content of nitrate nitrogen and ammonium nitrogen in different parts of P. ternate were determined. The contents of total alkaloid, free total organic acids and guanosine in the tuber were determined. The yield of bulbil and tuber was calculated. The test results showed that, with the NH4(+) -N/NO3(-) -N ratio increasing, the activity of nitrate reductase decreased, the content of nitrate nitrogen in the leaves, petioles and tuber increasing initially, then decreased, and the content of nitrate nitrogen in the root decreased. Meanwhile, with the NH4(+) -N/NO3(-) -N ratio increasing, the activity of glutamine synthetase in the leaves, petioles and root increased, the activity of glutamine synthetase in the tuber increasing initially, then decreased. The contents of ammonium nitrogen in the leaves, tuber and root increased initially, then decreased, and the contents of ammonium nitrogen in the petioles increased with the NH4(+)(-N/NO3(-)-N ratio increasing. The yield of bulbil and tuber were the highest at the NH4(+)-N/NO3(-) -N ratio of 75: 25. The content of total alkaloid and guanosine in the tuber were the highest at the NH4(+)-N/NO3(-) -N ratio of 0: 100, and the contents were 0.245% and 0.0197% respectively. With the NH4(+)-N/NO3(-) -N ratio of 50: 50, the content of free total organic acids was the highest, it reached 0.7%, however, the content of free total organic acids was the lowest at the NH4(+) -N/NO3(-) -N ratio of 0: 100. Nitrogen fertilization significant influences the nitrogen metabolism, the yield and main chemical composition of P. ternate.

Exploring the effects of nitrogen fertilization management alternatives on nitrate loss and crop yields in tile-drained fields in Illinois.

Science.gov (United States)

Jeong, Hanseok; Bhattarai, Rabin

2018-05-01

It is vital to manage the excessive use of nitrogen (N) fertilizer in corn production, the single largest consumer of N fertilizer in the United States, in order to achieve more sustainable agroecosystems. This study comprehensively explored the effects of N fertilization alternatives on nitrate loss and crop yields using the Root Zone Water Quality Model (RZWQM) in tile-drained fields in central Illinois. The RZWQM was tested for the prediction of tile flow, nitrate loss, and crop yields using eight years (1993-2000) of observed data and showed satisfactory model performances from statistical and graphical evaluations. Our model simulations demonstrated the maximum return to nitrogen (MRTN) rate (193 kgha -1 ), a newly advised N recommendation by the Illinois Nutrient Loss Reduction Strategy (INLRS), can be further reduced. Nitrate loss was reduced by 10.3% and 29.8%, but corn yields decreased by 0.3% and 1.9% at 156 and 150 kgha -1 of N fertilizer rate in the study sites A and E, respectively. Although adjustment of N fertilization timing presented a further reduction in nitrate loss, there was no optimal timing to ensure nitrate loss reduction and corn productivity. For site A, 100% spring application was the most productive and 40% fall, 10% pre-plant, and 50% side dress application generated the lowest nitrate loss. For site E, the conventional N application timing was verified as the best practice in both corn production and nitrate loss reduction. Compared to surface broadcast placement, injected N fertilizer in spring increased corn yield, but may also escalate nitrate loss. This study presented the need of an adaptive N fertilizer management due to the heterogeneity in agricultural systems, and raised the importance of timing and placement of N fertilizer, as well as further reduction in fertilizer rate to devise a better in-field N management practice. Copyright © 2018 Elsevier Ltd. All rights reserved.

Nitrogen uptake and assimilation by corn roots

International Nuclear Information System (INIS)

Yoneyama, Tadakatsu; Akiyama, Yoko; Kumazawa, Kikuo

1977-01-01

The site of nitrogen uptake in the apical root zone of corn was experimentally investigated. Two experiments were performed. The one is to see the assimilation of nitrate and ammonium and the effects of low temperature on it. The 4-day-old roots were treated with 15 N-labelled inorganic nitrogen of 20 ppm N in 5 x 10 -4 M CaSO 4 solution at 30 deg. C and 0 deg. C. The other is to see the nitrogen uptake at apical root zone and the utilization of newly absorbed nitrogen at the root top. The 4-day-old roots were transferred into 5 x 10 -4 M CaSO 4 solution containing 15 N-labelled ammonium nitrate of 40 ppm N. As a result, the effect of low temperature on the nitrogen uptake appeared to be more drastic in the case of nitrate than ammonium. The 15 N content of amino acids indicates that ammonium is assimilated into amino acids even at 0 deg. C, but nitrate is not. The ammonium nitrogen seemed to be absorbed at both cell dividing and elongating zones. On the other hand, nitrate nitrogen seemed to be strongly absorbed at cell elongating zone. The nitrogen in the apical part may be supplied not only by direct absorption but also by translocation from the basal part. The clear difference was found in the utilization of nitrate and ammonium nitrogen at the root top when the root was elongating. This may be due to the difference of assimilation products of inorganic nitrogen. Newly absorbed ammonium nitrogen is more utilizable for the growth of root top than nitrate nitrogen. (Iwakiri, K.)

Seasonal variations in the nitrogen isotope composition of Okinotori coral in the tropical western Pacific: A new proxy for marine nitrate dynamics

Science.gov (United States)

Yamazaki, Atsuko; Watanabe, Tsuyoshi; Ogawa, Nanako O.; Ohkouchi, Naohiko; Shirai, Kotaro; Toratani, Mitsuhiro; Uematsu, Mitsuo

2011-12-01

To demonstrate the utility of coral skeletons as a recorder of nitrate dynamics in the surface ocean, we collected coral skeletons of Porites lobata and determined their nitrogen isotope composition (δ15Ncoral) from 2002 to 2006. Skeletons were collected at Okinotori Island in southwestern Japan, far from any sources of terrestrial nitrogen. Nitrogen isotope compositions along the growth direction were determined at 800 μm intervals (˜1 month resolution) and compared against the skeletal carbon isotope composition (δ13Ccoral-carb), barium/calcium ratio (Ba/Ca), and Chlorophyll-a concentration (Chl-a). From 2002 to 2004, ratios of the δ15Ncoral varied between +0.8 and +8.3‰ with inverse variation to SST (r = -0.53). Ba/Ca ratios and Chl-a concentrations were also observed to be high during seasons with low SST. These results suggested that the vertical mixing that occurs during periods of low SST carries nutrients from deeper water (δ15NDIN; +5˜+6‰) to the sea surface. In 2005 onward, δ15Ncoral and Ba/Ca ratios also had positive peaks even in high SST during periods of transient upwelling caused by frequent large typhoons (maximum wind speed 30 m/s). In addition, low δ15Ncoral (+0.8˜+2.0‰) four months after the last typhoon implied nitrogen fixation because of the lack of typhoon upwelling through the four years record of δ15Ncoral. Variations in the δ13Ccoral-carb and δ15Ncoral were synchronized, suggesting that nitrate concentration could control zooxanthellae photosynthesis. Our results suggested that δ15Ncoral holds promise as a proxy for reconstructing the transport dynamics of marine nitrate and thus also a tool for estimating nitrate origins in the tropical and subtropical oceans.

Automated system measuring triple oxygen and nitrogen isotope ratios in nitrate using the bacterial method and N2 O decomposition by microwave discharge.

Science.gov (United States)

Hattori, Shohei; Savarino, Joel; Kamezaki, Kazuki; Ishino, Sakiko; Dyckmans, Jens; Fujinawa, Tamaki; Caillon, Nicolas; Barbero, Albane; Mukotaka, Arata; Toyoda, Sakae; Well, Reinhard; Yoshida, Naohiro

2016-12-30

Triple oxygen and nitrogen isotope ratios in nitrate are powerful tools for assessing atmospheric nitrate formation pathways and their contribution to ecosystems. N 2 O decomposition using microwave-induced plasma (MIP) has been used only for measurements of oxygen isotopes to date, but it is also possible to measure nitrogen isotopes during the same analytical run. The main improvements to a previous system are (i) an automated distribution system of nitrate to the bacterial medium, (ii) N 2 O separation by gas chromatography before N 2 O decomposition using the MIP, (iii) use of a corundum tube for microwave discharge, and (iv) development of an automated system for isotopic measurements. Three nitrate standards with sample sizes of 60, 80, 100, and 120 nmol were measured to investigate the sample size dependence of the isotope measurements. The δ 17 O, δ 18 O, and Δ 17 O values increased with increasing sample size, although the δ 15 N value showed no significant size dependency. Different calibration slopes and intercepts were obtained with different sample amounts. The slopes and intercepts for the regression lines in different sample amounts were dependent on sample size, indicating that the extent of oxygen exchange is also dependent on sample size. The sample-size-dependent slopes and intercepts were fitted using natural log (ln) regression curves, and the slopes and intercepts can be estimated to apply to any sample size corrections. When using 100 nmol samples, the standard deviations of residuals from the regression lines for this system were 0.5‰, 0.3‰, and 0.1‰, respectively, for the δ 18 O, Δ 17 O, and δ 15 N values, results that are not inferior to those from other systems using gold tube or gold wire. An automated system was developed to measure triple oxygen and nitrogen isotopes in nitrate using N 2 O decomposition by MIP. This system enables us to measure both triple oxygen and nitrogen isotopes in nitrate with comparable precision

The influence of different forms and concentrations of nitrogen on ...

African Journals Online (AJOL)

Reports the results of a study conducted to compare the growth and total reduced nitrogen content of the above ground components of Digitaria eriantha and Chloris gayana plants grown in saline conditions and supplied with different levels of nitrogen in the form of nitrate and ammonia; Chloris gayana and Digitaria ...

Nitrogen and phosphorus removed from a subsurface flow multi-stage filtration system purifying agricultural runoff.

Science.gov (United States)

Zhao, Yaqi; Huang, Lei; Chen, Yucheng

2018-07-01

Agricultural nonpoint source pollution has been increasingly serious in China since the 1990s. The main causes were excessive inputs of nitrogen fertilizer and pesticides. A multi-stage filtration system was built to test the purification efficiencies and removal characteristics of nitrogen and phosphorus when treating agricultural runoff. Simulated runoff pollution was prepared by using river water as source water based on the monitoring of local agricultural runoff. Experimental study had been performed from September to November 2013, adopting 12 h for flooding and 12 h for drying. The results showed that the system was made adaptive to variation of inflow quality and quantity, and had good removal for dissolved total nitrogen, total nitrogen, dissolved total phosphorus (DTP), and total phosphorus, and the average removal rate was 27%, 36%, 32%, and 48%, respectively. Except nitrate ([Formula: see text]), other forms of nitrogen and phosphorus all decreased with the increase of stages. Nitrogen was removed mainly in particle form the first stage, and mostly removed in dissolved form the second and third stage. Phosphorus was removed mainly in particulate during the first two stages, but the removal of particulate phosphorus and DTP were almost the same in the last stage. An approximate logarithmic relationship between removal loading and influent loading to nitrogen and phosphorus was noted in the experimental system, and the correlation coefficient was 0.78-0.94. [Formula: see text]: ammonium; [Formula: see text]: nitrite; [Formula: see text]: nitrate; DTN: dissolved total nitrogen; TN: total nitrogen; DTP: dissolved total phosphorus; TP: total phosphorus; PN: particulate nitrogen; PP: particulate phosphorus.

Nitrogen and Triple Oxygen Isotopic Analyses of Atmospheric Particulate Nitrate over the Pacific Ocean

Science.gov (United States)

Kamezaki, Kazuki; Hattori, Shohei; Iwamoto, Yoko; Ishino, Sakiko; Furutani, Hiroshi; Miki, Yusuke; Miura, Kazuhiko; Uematsu, Mitsuo; Yoshida, Naohiro

2017-04-01

Nitrate plays a significant role in the biogeochemical cycle. Atmospheric nitrate (NO3- and HNO3) are produced by reaction precursor as NOx (NO and NO2) emitted by combustion, biomass burning, lightning, and soil emission, with atmospheric oxidants like ozone (O3), hydroxyl radical (OH), peroxy radical and halogen oxides. Recently, industrial activity lead to increases in the concentrations of nitrogen species (NOx and NHy) throughout the environment. Because of the increase of the amount of atmospheric nitrogen deposition, the oceanic biogeochemical cycle are changed (Galloway et al., 2004; Kim et al., 2011). However, the sources and formation pathways of atmospheric nitrate are still uncertain over the Pacific Ocean because the long-term observation is limited. Stable isotope analysis is useful tool to gain information of sources, sinks and formation pathways. The nitrogen stable isotopic composition (δ15N) of atmospheric particulate NO3- can be used to posses information of its nitrogen sources (Elliott et al., 2007). Triple oxygen isotopic compositions (Δ17O = δ17O - 0.52 ×δ18O) of atmospheric particulate NO3- can be used as tracer of the relative importance of mass-independent oxygen bearing species (e.g. O3, BrO; Δ17O ≠ 0 ‰) and mass-dependent oxygen bearing species (e.g. OH radical; Δ17O ≈ 0 ‰) through the formation processes from NOx to NO3- in the atmosphere (Michalski et al., 2003; Thiemens, 2006). Here, we present the isotopic compositions of atmospheric particulate NO3- samples collected over the Pacific Ocean from 40˚ S to 68˚ N. We observed significantly low δ15N values for atmospheric particulate NO3- on equatorial Pacific Ocean during both cruises. Although the data is limited, combination analysis of δ15N and Δ17O values for atmospheric particulate NO3- showed the possibility of the main nitrogen source of atmospheric particulate NO3- on equatorial Pacific Ocean is ammonia oxidation in troposphere. Furthermore, the Δ17O values

Thermochemical nitrate reduction

International Nuclear Information System (INIS)

Cox, J.L.; Lilga, M.A.; Hallen, R.T.

1992-09-01

A series of preliminary experiments was conducted directed at thermochemically converting nitrate to nitrogen and water. Nitrates are a major constituent of the waste stored in the underground tanks on the Hanford Site, and the characteristics and effects of nitrate compounds on stabilization techniques must be considered before permanent disposal operations begin. For the thermochemical reduction experiments, six reducing agents (ammonia, formate, urea, glucose, methane, and hydrogen) were mixed separately with ∼3 wt% NO 3 - solutions in a buffered aqueous solution at high pH (13); ammonia and formate were also mixed at low pH (4). Reactions were conducted in an aqueous solution in a batch reactor at temperatures of 200 degrees C to 350 degrees C and pressures of 600 to 2800 psig. Both gas and liquid samples were analyzed. The specific components analyzed were nitrate, nitrite, nitrous oxide, nitrogen, and ammonia. Results of experimental runs showed the following order of nitrate reduction of the six reducing agents in basic solution: formate > glucose > urea > hydrogen > ammonia ∼ methane. Airnmonia was more effective under acidic conditions than basic conditions. Formate was also effective under acidic conditions. A more thorough, fundamental study appears warranted to provide additional data on the mechanism of nitrate reduction. Furthermore, an expanded data base and engineering feasibility study could be used to evaluate conversion conditions for promising reducing agents in more detail and identify new reducing agents with improved performance characteristics

A new method for the determination of the nitrogen content of nitrocellulose based on the molar ratio of nitrite-to-nitrate ions released after alkaline hydrolysis

Energy Technology Data Exchange (ETDEWEB)

Alinat, Elodie, E-mail: elodie.alinat@chimie-paristech.fr [PSL Research University, Chimie ParisTech, Laboratory of Physicochemistry of Electrolytes, Colloids and Analytical Sciences (PECSA), 11 rue Pierre et Marie Curie, 75005 Paris (France); Central Laboratory of Police Prefecture (LCPP), 39 bis rue de Dantzig, 75015 Paris (France); CNRS, UMR 7195 PECSA, 11 rue Pierre et Marie Curie, 75005 Paris (France); Sorbonne Universités, UPMC Univ Paris 06, LBM, 4 place Jussieu, F-75005 Paris (France); Delaunay, Nathalie, E-mail: nathalie.delaunay@espci.fr [PSL Research University, Chimie ParisTech, Laboratory of Physicochemistry of Electrolytes, Colloids and Analytical Sciences (PECSA), 11 rue Pierre et Marie Curie, 75005 Paris (France); CNRS, UMR 7195 PECSA, 11 rue Pierre et Marie Curie, 75005 Paris (France); Sorbonne Universités, UPMC Univ Paris 06, LBM, 4 place Jussieu, F-75005 Paris (France); Archer, Xavier, E-mail: xavier.archer@interieur.gouv.fr [Central Laboratory of Police Prefecture (LCPP), 39 bis rue de Dantzig, 75015 Paris (France); Mallet, Jean-Maurice, E-mail: jean-maurice.mallet@es.fr [École Normale Supérieure-PSL Research University, Département de Chimie, 24 rue Lhomond, 75005 Paris (France); Sorbonne Universités, UPMC Univ Paris 06, LBM, 4 place Jussieu, F-75005 Paris (France); CNRS, UMR 7203 LBM, F-75005 Paris (France); Gareil, Pierre, E-mail: pierre.gareil@chimie-paristech.fr [PSL Research University, Chimie ParisTech, Laboratory of Physicochemistry of Electrolytes, Colloids and Analytical Sciences (PECSA), 11 rue Pierre et Marie Curie, 75005 Paris (France); CNRS, UMR 7195 PECSA, 11 rue Pierre et Marie Curie, 75005 Paris (France); Sorbonne Universités, UPMC Univ Paris 06, LBM, 4 place Jussieu, F-75005 Paris (France)

2015-04-09

Highlights: • New insights into the nitrocellulose alkaline denitration mechanism. • Linear correlation for molar ratio of nitrite-to-nitrate ions and nitrogen content. • Capillary electrophoresis monitoring of nitrite and nitrate ions. • Applications to explosive and non-explosive nitrocellulose-containing samples. • Improved performances (including safety) over classical methods. - Abstract: A new method was proposed to determine the nitrogen content of nitrocelluloses (NCs). It is based on the finding of a linear relationship between the nitrogen content and the molar ratio of nitrite-to-nitrate ions released after alkaline hydrolysis. Capillary electrophoresis was used to monitor the concentration of nitrite and nitrate ions. The influences of hydrolysis time and molar mass of NC on the molar ratio of nitrite-to-nitrate ions were investigated, and new insights into the understanding of the alkaline denitration mechanism of NCs, underlying this analytical strategy is provided. The method was then tested successfully with various explosive and non-explosive NC-containing samples such as various daily products and smokeless gunpowders. Inherently to its principle exploiting a concentration ratio, this method shows very good repeatability in the determination of nitrogen content in real samples with relative standard deviation (n = 3) inferior to 1.5%, and also provides very significant advantages with respect to sample extraction, analysis time (1 h for alkaline hydrolysis, 3 min for electrophoretic separation), which was about 5 times shorter than for the classical Devarda's method, currently used in industry, and safety conditions (no need for preliminary drying NC samples, mild hydrolysis conditions with 1 M sodium hydroxide for 1 h at 60 °C)

A new method for the determination of the nitrogen content of nitrocellulose based on the molar ratio of nitrite-to-nitrate ions released after alkaline hydrolysis

International Nuclear Information System (INIS)

Alinat, Elodie; Delaunay, Nathalie; Archer, Xavier; Mallet, Jean-Maurice; Gareil, Pierre

2015-01-01

Highlights: • New insights into the nitrocellulose alkaline denitration mechanism. • Linear correlation for molar ratio of nitrite-to-nitrate ions and nitrogen content. • Capillary electrophoresis monitoring of nitrite and nitrate ions. • Applications to explosive and non-explosive nitrocellulose-containing samples. • Improved performances (including safety) over classical methods. - Abstract: A new method was proposed to determine the nitrogen content of nitrocelluloses (NCs). It is based on the finding of a linear relationship between the nitrogen content and the molar ratio of nitrite-to-nitrate ions released after alkaline hydrolysis. Capillary electrophoresis was used to monitor the concentration of nitrite and nitrate ions. The influences of hydrolysis time and molar mass of NC on the molar ratio of nitrite-to-nitrate ions were investigated, and new insights into the understanding of the alkaline denitration mechanism of NCs, underlying this analytical strategy is provided. The method was then tested successfully with various explosive and non-explosive NC-containing samples such as various daily products and smokeless gunpowders. Inherently to its principle exploiting a concentration ratio, this method shows very good repeatability in the determination of nitrogen content in real samples with relative standard deviation (n = 3) inferior to 1.5%, and also provides very significant advantages with respect to sample extraction, analysis time (1 h for alkaline hydrolysis, 3 min for electrophoretic separation), which was about 5 times shorter than for the classical Devarda's method, currently used in industry, and safety conditions (no need for preliminary drying NC samples, mild hydrolysis conditions with 1 M sodium hydroxide for 1 h at 60 °C)

Field Scale Groundwater Nitrate Loading Model for the Central Valley, California, 1945-Current

Science.gov (United States)

Harter, T.; Dzurella, K.; Bell, A.; Kourakos, G.

2015-12-01

Anthropogenic groundwater nitrate contamination in the Central Valley aquifer system, California, is widespread, with over 40% of domestic wells in some counties exceeding drinking water standards. Sources of groundwater nitrate include leaky municipal wastewater systems, municipal wastewater recharge, onsite wastewater treatment (septic) systems, atmospheric nitrogen deposition, animal farming, application of organic waste materials (sludge, biosolids, animal manure) to agricultural lands, and synthetic fertilizer. At the site or field scale, nitrogen inputs to the landscape are balanced by plant nitrogen uptake and harvest, atmospheric nitrogen losses, surface runoff of nitrogen, soil nitrogen storage changes, and leaching to groundwater. Irrigated agriculture is a dominant player in the Central Valley nitrogen cycle: The largest nitrogen fluxes are synthetic fertilizer and animal manure applications to cropland, crop nitrogen uptake, and groundwater nitrogen losses. We construct a historic field/parcel scale groundwater nitrogen loading model distinguishing urban and residential areas, individual animal farming areas, leaky wastewater lagoons, and approximately 50 different categories of agricultural crops. For non-agricultural landuses, groundwater nitrate loading is based on reported leaching values, animal population, and human population. For cropland, groundwater nitrate loading is computed from mass balance, taking into account diverse and historically changing management practices between different crops. Groundwater nitrate loading is estimated for 1945 to current. Significant increases in groundwater nitrate loading are associated with the expansion of synthetic fertilizer use in the 1950s to 1970s. Nitrate loading from synthetic fertilizer use has stagnated over the past 20 years due to improvements in nutrient use efficiency. However, an unbroken 60 year exponential increase in dairy production until the late 2000s has significantly impacted the

The physiological and biochemical mechanism of nitrate-nitrogen removal by water hyacinth from agriculture eutrophic wastewater

Directory of Open Access Journals (Sweden)

WU Wenwei

Full Text Available ABSTRACT Large amount of agriculturl wastewater containing high level nitrate-nitrogen (NO3 --N is produced from modern intensive agricultural production management due to the excessive use of chemical fertilizers and livestock scale farming. The hydroponic experiment of water hyacinth was conducted for analyzing the content of NO3 --N, soluble sugar content, N-transported the amino acid content and growth change in water hyacinth to explore its purification ability to remove NO3 --N from agriculture eutrophic wastewater and physiological and biochemical mechanism of this plant to remove NO3 --N. The results showed that the water hyacinth could effectively utilize the NO3 --N from agriculture eutrophic wastewater. Compared with the control, the contents of NO3 -change to NO3 --N in the root, leaf petiole and leaf blade of water hyacinth after treatment in the wastewater for a week was significantly higher than that in the control plants treated with tap water, and also the biomass of water hyacinth increased significantly, indicating that the accumulation of biomass due to the rapid growth of water hyacinth could transfer some amount of NO3 --N.13C-NMR analysis confirmed that water hyacinth would convert the part nitrogen absorbed from agriculture eutrophic wastewater to ammonia nitrogen, which increased the content of aspartic acid and glutamic acid, decreased the content of soluble sugar, sucrose and fructose and the content of N-storaged asparagine and glutamine, lead to enhance the synthesis of plant amino acids and promote the growth of plants. These results indicate that the nitrate in agriculture eutrophic wastewater can be utilized by water hyacinth as nitrogen nutrition, and can promote plant growth by using soluble sugar and amide to synthesis amino acids and protein.

Effect of nitrogen sources on the biodegradation of diesel fuel in unsaturated soil

International Nuclear Information System (INIS)

Brook, T. R.; Stiver, W. H.; Zytner, R. G.

1997-01-01

The various factors involved in controlling the rate and efficiency of the bioremediation process were studied, among them the type and concentration of contaminants, temperature, oxygen content and nutrient status. This study emphasized the effect of the nitrogen source on the degradation rate of diesel fuel in nutrient-limited soil. Various nitrogen sources were studied, including ammonium nitrate, urea, and urea oligomers. Treatment with urea produced the highest rate of hydrocarbon degradation, but ammonium levels were a better indicator of nutrient performance than total inorganic nitrogen. Other nitrogen sources produced little or no effect on the rate of biodegradation; there was no evidence that nitrate at 0.5 mg N/g concentration was inhibitory. 11 refs., 6 figs

Chronic nitrate exposure alters reproductive physiology in fathead minnows.

Science.gov (United States)

Kellock, Kristen A; Moore, Adrian P; Bringolf, Robert B

2018-01-01

Nitrate is a ubiquitous aquatic pollutant that is commonly associated with eutrophication and dead zones in estuaries around the world. At high concentrations nitrate is toxic to aquatic life but at environmental concentrations it has also been purported as an endocrine disruptor in fish. To investigate the potential for nitrate to cause endocrine disruption in fish, we conducted a lifecycle study with fathead minnows (Pimephales promelas) exposed to nitrate (0, 11.3, and 56.5 mg/L (total nitrate-nitrogen (NO 3 -N)) from nitrate-exposed males both 11-KT and vitellogenin were significantly induced when compared with controls. No significant differences occurred for body mass, condition factor, or GSI among males and intersex was not observed in any of the nitrate treatments. Nitrate-exposed females also had significant increases in vitellogenin compared to controls but no significant differences for mass, condition factor, or GSI were observed in nitrate exposed groups. Estradiol was used as a positive control for vitellogenin induction. Our findings suggest that environmentally relevant nitrate levels may disrupt steroid hormone synthesis and/or metabolism in male and female fish and may have implications for fish reproduction, watershed management, and regulation of nutrient pollution. Copyright © 2017 Elsevier Ltd. All rights reserved.

The nitrogen cycle in anaerobic methanotrophic mats of the Black Sea is linked to sulfate reduction and biomass decomposition.

Science.gov (United States)

Siegert, Michael; Taubert, Martin; Seifert, Jana; von Bergen-Tomm, Martin; Basen, Mirko; Bastida, Felipe; Gehre, Matthias; Richnow, Hans-Hermann; Krüger, Martin

2013-11-01

Anaerobic methanotrophic (ANME) mats host methane-oxidizing archaea and sulfate-reducing prokaryotes. Little is known about the nitrogen cycle in these communities. Here, we link the anaerobic oxidation of methane (AOM) to the nitrogen cycle in microbial mats of the Black Sea by using stable isotope probing. We used four different (15)N-labeled sources of nitrogen: dinitrogen, nitrate, nitrite and ammonium. We estimated the nitrogen incorporation rates into the total biomass and the methyl coenzyme M reductase (MCR). Dinitrogen played an insignificant role as nitrogen source. Assimilatory and dissimilatory nitrate reduction occurred. High rates of nitrate reduction to dinitrogen were stimulated by methane and sulfate, suggesting that oxidation of reduced sulfur compounds such as sulfides was necessary for AOM with nitrate as electron acceptor. Nitrate reduction to dinitrogen occurred also in the absence of methane as electron donor but at six times slower rates. Dissimilatory nitrate reduction to ammonium was independent of AOM. Ammonium was used for biomass synthesis under all conditions. The pivotal enzyme in AOM coupled to sulfate reduction, MCR, was synthesized from nitrate and ammonium. Results show that AOM coupled to sulfate reduction along with biomass decomposition drive the nitrogen cycle in the ANME mats of the Black Sea and that MCR enzymes are involved in this process. © 2013 Federation of European Microbiological Societies. Published by John Wiley & Sons Ltd. All rights reserved.

Global Patterns of Legacy Nitrate Storage in the Vadose Zone

Science.gov (United States)

Ascott, M.; Gooddy, D.; Wang, L.; Stuart, M.; Lewis, M.; Ward, R.; Binley, A. M.

2017-12-01

Global-scale nitrogen (N) budgets have been developed to quantify the impact of man's influence on the nitrogen cycle. However, these budgets often do not consider legacy effects such as accumulation of nitrate in the deep vadose zone. In this presentation we show that the vadose zone is an important store of nitrate which should be considered in future nitrogen budgets for effective policymaking. Using estimates of depth to groundwater and nitrate leaching for 1900-2000, we quantify for the first time the peak global storage of nitrate in the vadose zone, estimated as 605 - 1814 Teragrams (Tg). Estimates of nitrate storage are validated using previous national and basin scale estimates of N storage and observed groundwater nitrate data for North America and Europe. Nitrate accumulation per unit area is greatest in North America, China and Central and Eastern Europe where thick vadose zones are present and there is an extensive history of agriculture. In these areas the long solute travel time in the vadose zone means that the anticipated impact of changes in agricultural practices on groundwater quality may be substantially delayed. We argue that in these areas use of conventional nitrogen budget approaches is inappropriate and their continued use will lead to significant errors.

Global sensitivity and uncertainty analysis of the nitrate leaching and crop yield simulation under different water and nitrogen management practices

Science.gov (United States)

Agricultural system models have become important tools in studying water and nitrogen (N) dynamics, as well as crop growth, under different management practices. Complexity in input parameters often leads to significant uncertainty when simulating dynamic processes such as nitrate leaching or crop y...

Ground-water discharge and base-flow nitrate loads of nontidal streams, and their relation to a hydrogeomorphic classification of the Chesapeake Bay Watershed, middle Atlantic Coast

Science.gov (United States)

Bachman, L. Joseph; Lindsey, Bruce D.; Brakebill, John W.; Powars, David S.

1998-01-01

Existing data on base-flow and groundwater nitrate loads were compiled and analyzed to assess the significance of groundwater discharge as a source of the nitrate load to nontidal streams of the Chesapeake Bay watershed. These estimates were then related to hydrogeomorphic settings based on lithology and physiographic province to provide insight on the areal distribution of ground-water discharge. Base-flow nitrate load accounted for 26 to about 100 percent of total-flow nitrate load, with a median value of 56 percent, and it accounted for 17 to 80 percent of total-flow total-nitrogen load, with a median value of 48 percent. Hydrograph separations were conducted on continuous streamflow records from 276 gaging stations within the watershed. The values for base flow thus calculated were considered an estimate of ground-water discharge. The ratio of base flow to total flow provided an estimate of the relative importance of ground-water discharge within a basin. Base-flow nitrate loads, total-flow nitrate loads, and total-flow total-nitrogen loads were previously computed from water-quality and discharge measurements by use of a regression model. Base-flow nitrate loads were available from 78 stations, total-flow nitrate loads were available from 86 stations, and total-flow total-nitrogen loads were available for 48 stations. The percentage of base-flow nitrate load to total-flow nitrate load could be computed for 57 stations, whereas the percentage of base-flow nitrate load to totalflow total-nitrogen load could be computed for 36 stations. These loads were divided by the basin area to obtain yields, which were used to compare the nitrate discharge from basins of different sizes. The results indicate that ground-water discharge is a significant source of water and nitrate to the total streamflow and nitrate load. Base flow accounted for 16 to 92 percent of total streamflow at the 276 sampling sites, with a median value of 54 percent. It is estimated that of the 50

Nitrate control strategies in an activated sludge wastewater treatment process

Energy Technology Data Exchange (ETDEWEB)

Shen, Wenhao; Tao, Erpan; Chen, Xiaoquan; Liu, Dawei [South China University of Technology, Guangzhou (China); Liu, Hongbin [Kyung Hee University, Yongin (Korea, Republic of)

2014-03-15

We studied nitrate control strategies in an activated sludge wastewater treatment process (WWTP) based on the activated sludge model. Two control strategies, back propagation for proportional-integral-derivative (BP-PID) and adaptive-network based fuzzy inference systems (ANFIS), are applied in the WWTP. The simulation results show that the simple local constant setpoint control has poor control effects on the nitrate concentration control. However, the ANFIS (4*1) controller, which considers not only the local constant setpoint control of the nitrate concentration, but also three important indices in the effluent--ammonia concentration, total suspended sludge concentration and total nitrogen concentration--demonstrates good control performance. The results also prove that ANFIS (4*1) controller has better control performance than that of the controllers PI, BP-PID and ANFIS (2*1), and that the ANFIS (4*1) controller is effective in improving the effluent quality and maintaining the stability of the effluent quality.

Efficiency of nitrophosphates of varying water solubility with respect to their nitrogen (15N) and phosphorus (32P) utilisation

International Nuclear Information System (INIS)

Motsara, M.R.; Leela Bhai, K.S.; Mev Singh; Datta, N.P.

1975-01-01

Nitrophosphates of different water soluble P superphosphate and super plus ammonium nitrate were compared by raising wheat as a test crop on alluvial soil of Delhi. Phosphorus was tagged with 32 P and the ammonical and nitrate nitrogen was alternately tagged with 15 N. With increasing the water-soluble P content in nitrophosphate, increasing amount of grain yield and higher uptake of total N and P were recorded. The percent phosphorus derived in the plant from the fertilizer and the percent phosphorus utilization was higher from the nitrophosphates of higher eater soluble P content. It was also higher under the application of superphosphate plus ammonium nitrate than superphosphate alone. A greater amount of ammonical nitrogen was utilized by the crop than nitrate form of nitrogen. (author)

Effects of Nitrogen and Water on Soil Enzyme Activity and Soil Microbial Biomass in Stipa baicalensis Steppe,Inner Mongolia of North China

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WANG Jie

2014-06-01

Full Text Available In this paper, eight nitrogen treatments were applied at 0 g·m -2(N0, 1.5 g·m -2(N15, 3.0 g·m -2(N30, 5.0 g·m -2(N50, 10.0 g·m -2(N100, 15.0 g·m -2(N150, 20.0 g·m -2(N200, 30.0 g·m -2(N300 as NH 4 NO 3 and adding water to simulate summer rainfall of 100 mm, the interactive experiment was set to explore the effects of nitrogen and water addition in Stipa baicalensis steppe on soil nutrients, enzyme activities and soil microbial biomass. The results showed that the nitrogen and water addition changed soil physico-chemical factors obviously, the content of soil total organic carbon, total nitrogen, nitrate nitrogen and ammonium nitrogen increased along with the increasing of application rate of nitrogen, on the contrary, the soil pH value had decreasing trend. Appropriate application of nitrogen could enhance the activity of urease and catalase but decreased the activity of polyphenol oxidase. Nitrogen and water addition had significant effect on soil microbial biomass C and N. Higher level of N fertilizer significantly reduced microbial biomass C, and the microbial biomass N was on the rise with the application rate of nitrogen. The addition of water could slow the inhibition of nitrogen to microorganism and increase the microbial biomass C and N. A closed relationship existed in soil nutrient, activities of soil enzyme and soil microbial biomass C and N. The significantly positive correlation existed between total N, organic C, nitrate N and catalase, significantly negative correlation between nitrate N, ammonium N, total N and polyphenol oxidase. Microbial biomass N was significantly positive correlated with total N, nitrate N, ammonium N, catalase, phosphatase, and was negative correlated with polyphenol oxidase. Microbial biomass C was significantly positive correlated with polyphenol oxidase, and was negative correlated with catalase.

Tidal pumping facilitates dissimilatory nitrate reduction in intertidal marshes

Science.gov (United States)

Zheng, Yanling; Hou, Lijun; Liu, Min; Liu, Zhanfei; Li, Xiaofei; Lin, Xianbiao; Yin, Guoyu; Gao, Juan; Yu, Chendi; Wang, Rong; Jiang, Xiaofen

2016-01-01

Intertidal marshes are alternately exposed and submerged due to periodic ebb and flood tides. The tidal cycle is important in controlling the biogeochemical processes of these ecosystems. Intertidal sediments are important hotspots of dissimilatory nitrate reduction and interacting nitrogen cycling microorganisms, but the effect of tides on dissimilatory nitrate reduction, including denitrification, anaerobic ammonium oxidation and dissimilatory nitrate reduction to ammonium, remains unexplored in these habitats. Here, we use isotope-tracing and molecular approaches simultaneously to show that both nitrate-reduction activities and associated functional bacterial abundances are enhanced at the sediment-tidal water interface and at the tide-induced groundwater fluctuating layer. This pattern suggests that tidal pumping may sustain dissimilatory nitrate reduction in intertidal zones. The tidal effect is supported further by nutrient profiles, fluctuations in nitrogen components over flood-ebb tidal cycles, and tidal simulation experiments. This study demonstrates the importance of tides in regulating the dynamics of dissimilatory nitrate-reducing pathways and thus provides new insights into the biogeochemical cycles of nitrogen and other elements in intertidal marshes. PMID:26883983

Nitrogen-source preference in blueberry (Vaccinium sp.): Enhanced shoot nitrogen assimilation in response to direct supply of nitrate.

Science.gov (United States)

Alt, Douglas S; Doyle, John W; Malladi, Anish

2017-09-01

Blueberry (Vaccinium sp.) is thought to display a preference for the ammonium (NH 4 + ) form over the nitrate (NO 3 - ) form of inorganic nitrogen (N). This N-source preference has been associated with a generally low capacity to assimilate the NO 3 - form of N, especially within the shoot tissues. Nitrate assimilation is mediated by nitrate reductase (NR), a rate limiting enzyme that converts NO 3 - to nitrite (NO 2 - ). We investigated potential limitations of NO 3 - assimilation in two blueberry species, rabbiteye (Vaccinium ashei) and southern highbush (Vaccinium corymbosum) by supplying NO 3 - to the roots, leaf surface, or through the cut stem. Both species displayed relatively low but similar root uptake rates for both forms of inorganic N. Nitrate uptake through the roots transiently increased NR activity by up to 3.3-fold and root NR gene expression by up to 4-fold. However, supplying NO 3 - to the roots did not increase its transport in the xylem, nor did it increase NR activity in the leaves, indicating that the acquired N was largely assimilated or stored within the roots. Foliar application of NO 3 - increased leaf NR activity by up to 3.5-fold, but did not alter NO 3 - metabolism-related gene expression, suggesting that blueberries are capable of post translational regulation of NR activity in the shoots. Additionally, supplying NO 3 - to the cut ends of stems resulted in around a 5-fold increase in NR activity, a 10-fold increase in NR transcript accumulation, and up to a 195-fold increase in transcript accumulation of NITRITE REDUCTASE (NiR1) which codes for the enzyme catalyzing the conversion of NO 2 - to NH 4 + . These data indicate that blueberry shoots are capable of assimilating NO 3 - when it is directly supplied to these tissues. Together, these data suggest that limitations in the uptake and translocation of NO 3 - to the shoots may limit overall NO 3 - assimilation capacity in blueberry. Copyright © 2017 Elsevier GmbH. All rights reserved.

Export of nitrogen from catchments: A worldwide analysis

International Nuclear Information System (INIS)

Alvarez-Cobelas, M.; Angeler, D.G.; Sanchez-Carrillo, S.

2008-01-01

This study reviews nitrogen export rates from 946 rivers of the world to determine the influence of quantitative (runoff, rainfall, inhabitant density, catchment area, percentage of land use cover, airborne deposition, fertilizer input) and qualitative (dominant type of forest, occurrence of stagnant waterbodies, dominant land use, occurrence of point sources, runoff type) environmental factors on nitrogen fluxes. All fractions (total, nitrate, ammonia, dissolved organic and particulate organic) of nitrogen export showed a left-skewed distribution, which suggests a relatively pristine condition for most systems. Total nitrogen export showed the highest variability whereas total organic nitrogen export comprised the dominant fraction of export. Nitrogen export rates were only weakly explained by our qualitative and quantitative environmental variables. Our study suggests that the consideration of spatial and temporal scales is important for predicting nitrogen export rates using simple and easy-to-get environmental variables. Regionally based modelling approaches prove more useful than global-scale analyses. - Spatial and temporal scales are important determinants for nitrogen export from catchments and emphasis should be put on regional approaches

A comparison of total bound nitrogen with the sum of inorganic nitrogen in the present partice in the German Water Regulation Act for monitoring of nitrogen compounds; Ein Vergleich des gesamten gebundenen Stickstoffs mit der Summe des anorganischen Stickstoffs in der derzeitigen Gesetzespraxis zur Ueberwachung auf Stickstoffverbindungen

Energy Technology Data Exchange (ETDEWEB)

Rinne, D.; Seckert-Knopp, W. [Landesamt fuer Wasserwirtschaft Rheinland-Pfalz, Mainz (Germany)

1997-11-01

The results of the analysis of nitrate, nitrite, ammonia, and total bound nitrogen (TN{sub b}) from 331 samples of municipal and 322 samples of industrial waste water effluents were compiled in the years 1990 to 1994. These data were evaluated due to - the comparison of the sum of inorganic nitrogen ({Sigma} N{sub anorg.}) of nitrate, nitrite, and ammonia to TN{sub b} in view of a planned exchange in the German Waste Water Regulation Act - the calculation of organic bound nitrogen (N{sub org.}) - the usefulness to generate sufficient data for balancing the `content of nitrogen` in water systems. The results of our investigations are: The analytical results from the sum of inorganic nitrogen and TN{sub b} are in very good agreement. In most cases the TN{sub b} values were higher than those of {Sigma} N{sub anorg.} This is plausible because most samples contain a certain amount of organic bound nitrogen. Therefore the differences between the results of this two analytical parameters should express the term `organic bound nitrogen` (N{sub org.}). This substraction is an excellent method to estimate this value without a further analytical procedure. The data from our investigation underline this quite clearly. In contrary to the determination of the single compounds ammonia, nitrate, and nitrite the TN{sub b} as a sum parameter is fast, instrument based, can be automated and shows a sufficient limit of determination. This method allows the evaluation of a high data density for water monitoring and balancing the `content of nitrogen` in water systems. A further advantage is the minimizing of errors when applying only one analytical method instead of three. (orig.) [Deutsch] Die Analysenergebnisse der Parameter Nitrit, Nitrat, Ammonium sowie die davon abgeleiteten Parameter `Summe anorganischer Stickstoff` ({Sigma} N{sub anorg.}) und `gesamter gebundener Stickstoff` (TN{sub b}) wurden fuer 331 Proben kommunaler und 322 Proben industrieller Abwasseranlagen aus den Jahren

Long-term nitrogen behavior under treated wastewater infiltration basins in a soil-aquifer treatment (SAT) system.

Science.gov (United States)

Mienis, Omer; Arye, Gilboa

2018-05-01

The long term behavior of total nitrogen and its components was investigated in a soil aquifer treatment system of the Dan Region Reclamation Project (Shafdan), Tel-Aviv, Israel. Use is made of the previous 40 years' secondary data for the main nitrogen components (ammonium, nitrate and organic nitrogen) in recharged effluent and observation wells located inside an infiltration basin. The wells were drilled to 106 and 67 m, both in a similar position within the basin. The transport characteristics of each nitrogen component were evaluated based on chloride travel-time, calculated by a cross-correlation between its concentration in the recharge effluent and the observation wells. Changes in the source of recharge effluent, wastewater treatment technology and recharge regime were found to be the main factors affecting turnover in total nitrogen and its components. During aerobic operation of the infiltration basins, most organic nitrogen and ammonium will be converted to nitrate. Total nitrogen removal in the upper part of the aquifer was found to be 47-63% by denitrification and absorption, and overall removal, including the lower part of the aquifer, was 49-83%. To maintain the aerobic operation of the infiltration fields, the total nitrogen load should remain below 10 mg/L. Above this limit, ammonium and organic nitrogen will be displaced into the aquifer. Copyright © 2018 Elsevier Ltd. All rights reserved.

Ammonium and nitrate tolerance in lichens

Energy Technology Data Exchange (ETDEWEB)

Hauck, Markus, E-mail: mhauck@gwdg.d [Department of Plant Ecology, Albrecht von Haller Institute of Plant Sciences, University of Goettingen, Untere Karspuele 2, 37073 Goettingen (Germany)

2010-05-15

Since lichens lack roots and take up water, solutes and gases over the entire thallus surface, these organisms respond more sensitively to changes in atmospheric purity than vascular plants. After centuries where effects of sulphur dioxide and acidity were in the focus of research on atmospheric chemistry and lichens, recently the globally increased levels of ammonia and nitrate increasingly affect lichen vegetation and gave rise to intense research on the tolerance of lichens to nitrogen pollution. The present paper discusses the main findings on the uptake of ammonia and nitrate in the lichen symbiosis and to the tolerance of lichens to eutrophication. Ammonia and nitrate are both efficiently taken up under ambient conditions. The tolerance to high nitrogen levels depends, among others, on the capability of the photobiont to provide sufficient amounts of carbon skeletons for ammonia assimilation. Lowly productive lichens are apparently predisposed to be sensitive to excess nitrogen. - Eutrophication has become a global threat for lichen diversity.

CHANGES IN NITROGEN FERTILIZERS MARKET IN POLAND IN 2000-2010

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Arkadiusz Zalewski

2013-12-01

Full Text Available The article describes the evolution of production, consumption and foreign trade of nitrogen fertilizers in Poland in years 2000-2010. The structure of the use of nitrogen fertilizers, foreign trade and balance of the market of urea, ammonium sulfate, ammonium nitrate, calcium ammonium nitrate, ammonium phosphate and UAN were analysed. Geographical directions of foreign trade were specified. The results showed that the domestic fertilizer sector is fully self-sufficient in the area of production of various nitrogen fertilizers. The most commonly used nitrogen fertilizers were: ammonium nitrate, urea and calcium ammonium nitrate while the importance of ammonium nitrate was clearly reduced. Ammonium sulphate and UAN produced mainly for export, and ammonium nitrate for the domestic market.

Nitrate-nitrogen losses through subsurface drainage under various agricultural land covers.

Science.gov (United States)

Qi, Zhiming; Helmers, Matthew J; Christianson, Reid D; Pederson, Carl H

2011-01-01

Nitrate-nitrogen (NO₃-N) loading to surface water bodies from subsurface drainage is an environmental concern in the midwestern United States. The objective of this study was to investigate the effect of various land covers on NO₃-N loss through subsurface drainage. Land-cover treatments included (i) conventional corn ( L.) (C) and soybean [ (L.) Merr.] (S); (ii) winter rye ( L.) cover crop before corn (rC) and before soybean (rS); (iii) kura clover ( M. Bieb.) as a living mulch for corn (kC); and (iv) perennial forage of orchardgrass ( L.) mixed with clovers (PF). In spring, total N uptake by aboveground biomass of rye in rC, rye in rS, kura clover in kC, and grasses in PF were 14.2, 31.8, 87.0, and 46.3 kg N ha, respectively. Effect of land covers on subsurface drainage was not significant. The NO₃-N loss was significantly lower for kC and PF than C and S treatments (p rye cover crop did not reduce NO₃-N loss, but NO₃-N concentration was significantly reduced in rC during March to June and in rS during July to November (p rye cover crop on NO-N loss reduction needs further investigation under conditions of different N rates, wider weather patterns, and fall tillage. by the American Society of Agronomy, Crop Science Society of America, and Soil Science Society of America, Inc.

Nitrogen on Mars: Insights from Curiosity

Science.gov (United States)

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

2017-01-01

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

Mitochondrial respiratory pathways modulate nitrate sensing and nitrogen-dependent regulation of plant architecture in Nicotiana sylvestris.

Science.gov (United States)

Pellny, Till K; Van Aken, Olivier; Dutilleul, Christelle; Wolff, Tonja; Groten, Karin; Bor, Melike; De Paepe, Rosine; Reyss, Agnès; Van Breusegem, Frank; Noctor, Graham; Foyer, Christine H

2008-06-01

Mitochondrial electron transport pathways exert effects on carbon-nitrogen (C/N) relationships. To examine whether mitochondria-N interactions also influence plant growth and development, we explored the responses of roots and shoots to external N supply in wild-type (WT) Nicotiana sylvestris and the cytoplasmic male sterile II (CMSII) mutant, which has a N-rich phenotype. Root architecture in N. sylvestris seedlings showed classic responses to nitrate and sucrose availability. In contrast, CMSII showed an altered 'nitrate-sensing' phenotype with decreased sensitivity to C and N metabolites. The WT growth phenotype was restored in CMSII seedling roots by high nitrate plus sugars and in shoots by gibberellic acid (GA). Genome-wide cDNA-amplified fragment length polymorphism (AFLP) analysis of leaves from mature plants revealed that only a small subset of transcripts was altered in CMSII. Tissue abscisic acid content was similar in CMSII and WT roots and shoots, and growth responses to zeatin were comparable. However, the abundance of key transcripts associated with GA synthesis was modified both by the availability of N and by the CMSII mutation. The CMSII mutant maintained a much higher shoot/root ratio at low N than WT, whereas no difference was observed at high N. Shoot/root ratios were strikingly correlated with root amines/nitrate ratios, values of <1 being characteristic of high N status. We propose a model in which the amine/nitrate ratio interacts with GA signalling and respiratory pathways to regulate the partitioning of biomass between shoots and roots.

Formation kinetics and abundance of organic nitrates in α-pinene ozonolysis

Science.gov (United States)

Berkemeier, Thomas; Ammann, Markus; Pöschl, Ulrich; Shiraiwa, Manabu

2016-04-01

Formation of organic nitrates affects the total atmospheric budget of oxidized nitrogen (NOy) and alters the total aerosol mass yield from secondary sources. We investigated the formation of organic nitrate species during ozonolysis of α-pinene and subsequent formation of secondary organic aerosols (SOA) using the short-lived radioactive tracer 13N inside an aerosol flow reactor (Ammann et al., 2001). The results represent direct measurements of the organic nitrate content of α-pinene secondary aerosol and give insight into the kinetics of organic nitrate formation. Organic nitrates constituted up to 40 % of aerosol mass with a pronounced influence during the initial period of particle growth. Kinetic modelling, as well as additional experiments using OH scavengers and UV irradiation, suggests that organic peroxy radicals (RO2) from the reaction of α-pinene with secondarily produced OH are important intermediates in the organic nitrate formation process. Direct oxidation of α-pinene by NO3 was found to be a less efficient pathway for formation of particle phase nitrate. The organic nitrate content decreased very slightly with an increase of relative humidity on the experimental time scale. The experiments show a tight correlation between organic nitrate content and SOA number concentrations, implying that organic nitrates play an important role in nucleation and growth of nanoparticles. Since present in large amounts in organic aerosol, organic nitrates deposited in the lung might have implications for human health as they release nitric acid upon hydrolysis, especially in regions influenced by urban pollution and large sources of monoterpene SOA precursors. References Ammann et al. (2001) Radiochimica Acta 89, 831.

Nitrate capture and slow release in biochar amended compost and soil.

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Nikolas Hagemann

Full Text Available Slow release of nitrate by charred organic matter used as a soil amendment (i.e. biochar was recently suggested as potential mechanism of nutrient delivery to plants which may explain some agronomic benefits of biochar. So far, isolated soil-aged and composted biochar particles were shown to release considerable amounts of nitrate only in extended (>1 h extractions ("slow release". In this study, we quantified nitrate and ammonium release by biochar-amended soil and compost during up to 167 h of repeated extractions in up to six consecutive steps to determine the effect of biochar on the overall mineral nitrogen retention. We used composts produced from mixed manures amended with three contrasting biochars prior to aerobic composting and a loamy soil that was amended with biochar three years prior to analysis and compared both to non-biochar amended controls. Composts were extracted with 2 M KCl at 22°C and 65°C, after sterilization, after treatment with H2O2, after removing biochar particles or without any modification. Soils were extracted with 2 M KCl at 22°C. Ammonium was continuously released during the extractions, independent of biochar amendment and is probably the result of abiotic ammonification. For the pure compost, nitrate extraction was complete after 1 h, while from biochar-amended composts, up to 30% of total nitrate extracted was only released during subsequent extraction steps. The loamy soil released 70% of its total nitrate amount in subsequent extractions, the biochar-amended soil 58%. However, biochar amendment doubled the amount of total extractable nitrate. Thus, biochar nitrate capture can be a relevant contribution to the overall nitrate retention in agroecosystems. Our results also indicate that the total nitrate amount in biochar amended soils and composts may frequently be underestimated. Furthermore, biochars could prevent nitrate loss from agroecosystems and may be developed into slow-release fertilizers to

TRANC – a novel fast-response converter to measure total reactive atmospheric nitrogen

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V. Wolff

2012-05-01

Full Text Available The input and loss of plant available nitrogen (reactive nitrogen: Nr from/to the atmosphere can be an important factor for the productivity of ecosystems and thus for its carbon and greenhouse gas exchange. We present a novel converter for reactive nitrogen (TRANC: Total Reactive Atmospheric Nitrogen Converter, which offers the opportunity to quantify the sum of all airborne reactive nitrogen compounds (∑Nr in high time resolution. The basic concept of the TRANC is the full conversion of all Nr to nitrogen monoxide (NO within two reaction steps. Initially, reduced Nr compounds are being oxidised, and oxidised Nr compounds are thermally converted to lower oxidation states. Particulate Nr is being sublimated and oxidised or reduced afterwards. In a second step, remaining higher nitrogen oxides or those generated in the first step are catalytically converted to NO with carbon monoxide used as reduction gas. The converter is combined with a fast response chemiluminescence detector (CLD for NO analysis and its performance was tested for the most relevant gaseous and particulate Nr species under both laboratory and field conditions. Recovery rates during laboratory tests for NH3 and NO2 were found to be 95 and 99%, respectively, and 97% when the two gases were combined. In-field longterm stability over an 11-month period was approved by a value of 91% for NO2. Effective conversion was also found for ammonium and nitrate containing particles. The recovery rate of total ambient Nr was tested against the sum of individual measurements of NH3, HNO3, HONO, NH4+, NO3−, and NOx using a combination of different well-established devices. The results show that the TRANC-CLD system precisely captures fluctuations in ∑Nr concentrations and also matches the sum of all individual Nr compounds measured by the different single techniques. The TRANC features a specific design with very short distance between the sample air inlet and the place where the thermal

Soil nitrate testing supports nitrogen management in irrigated annual crops

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Patricia A. Lazicki

2016-12-01

Full Text Available Soil nitrate (NO3− tests are an integral part of nutrient management in annual crops. They help growers make field-specific nitrogen (N fertilization decisions, use N more efficiently and, if necessary, comply with California's Irrigated Lands Regulatory Program, which requires an N management plan and an estimate of soil NO3− from most growers. As NO3− is easily leached into deeper soil layers and groundwater by rain and excess irrigation water, precipitation and irrigation schedules need to be taken into account when sampling soil and interpreting test results. We reviewed current knowledge on best practices for taking and using soil NO3− tests in California irrigated annual crops, including how sampling for soil NO3− differs from sampling for other nutrients, how tests performed at different times of the year are interpreted and some of the special challenges associated with NO3− testing in organic systems.

Nitrate-induced genes in tomato roots. Array analysis reveals novel genes that may play a role in nitrogen nutrition.

Science.gov (United States)

Wang, Y H; Garvin, D F; Kochian, L V

2001-09-01

A subtractive tomato (Lycopersicon esculentum) root cDNA library enriched in genes up-regulated by changes in plant mineral status was screened with labeled mRNA from roots of both nitrate-induced and mineral nutrient-deficient (-nitrogen [N], -phosphorus, -potassium [K], -sulfur, -magnesium, -calcium, -iron, -zinc, and -copper) tomato plants. A subset of cDNAs was selected from this library based on mineral nutrient-related changes in expression. Additional cDNAs were selected from a second mineral-deficient tomato root library based on sequence homology to known genes. These selection processes yielded a set of 1,280 mineral nutrition-related cDNAs that were arrayed on nylon membranes for further analysis. These high-density arrays were hybridized with mRNA from tomato plants exposed to nitrate at different time points after N was withheld for 48 h, for plants that were grown on nitrate/ammonium for 5 weeks prior to the withholding of N. One hundred-fifteen genes were found to be up-regulated by nitrate resupply. Among these genes were several previously identified as nitrate responsive, including nitrate transporters, nitrate and nitrite reductase, and metabolic enzymes such as transaldolase, transketolase, malate dehydrogenase, asparagine synthetase, and histidine decarboxylase. We also identified 14 novel nitrate-inducible genes, including: (a) water channels, (b) root phosphate and K(+) transporters, (c) genes potentially involved in transcriptional regulation, (d) stress response genes, and (e) ribosomal protein genes. In addition, both families of nitrate transporters were also found to be inducible by phosphate, K, and iron deficiencies. The identification of these novel nitrate-inducible genes is providing avenues of research that will yield new insights into the molecular basis of plant N nutrition, as well as possible networking between the regulation of N, phosphorus, and K nutrition.

NITRATE REDUCTION PROGRAM AT THE LINE CREEK OPERATION

OpenAIRE

Jeff W Hawley

2015-01-01

Blasting activities at the Line Creek operation are releasing oxides of nitrogen and arecontributing to chemical changes in the surrounding watersheds. Through analysis of themechanisms of nitrogen release, history of explosive usage, historical nitrate release, changingregulatory requirements, strategy analysis and social impacts associated with the release ofnitrates a nitrate reduction plan will be established.The paper develops the framework for engineering groups, operations groups andma...

Evidence for indigenous nitrogen in sedimentary and aeolian deposits from the Curiosity rover investigations at Gale crater, Mars

Science.gov (United States)

Stern, Jennifer C.; Sutter, Brad; Freissinet, Caroline; Navarro-González, Rafael; McKay, Christopher P.; Archer, P. Douglas; Buch, Arnaud; Brunner, Anna E.; Coll, Patrice; Eigenbrode, Jennifer L.; Fairen, Alberto G.; Franz, Heather B.; Glavin, Daniel P.; Kashyap, Srishti; McAdam, Amy C.; Ming, Douglas W.; Steele, Andrew; Szopa, Cyril; Wray, James J.; Martín-Torres, F. Javier; Zorzano, Maria-Paz; Conrad, Pamela G.; Mahaffy, Paul R.; Kemppinen, Osku; Bridges, Nathan; Johnson, Jeffrey R.; Minitti, Michelle; Cremers, David; Bell, James F.; Edgar, Lauren; Farmer, Jack; Godber, Austin; Wadhwa, Meenakshi; Wellington, Danika; McEwan, Ian; Newman, Claire; Richardson, Mark; Charpentier, Antoine; Peret, Laurent; King, Penelope; Blank, Jennifer; Weigle, Gerald; Schmidt, Mariek; Li, Shuai; Milliken, Ralph; Robertson, Kevin; Sun, Vivian; Baker, Michael; Edwards, Christopher; Ehlmann, Bethany; Farley, Kenneth; Griffes, Jennifer; Grotzinger, John; Miller, Hayden; Newcombe, Megan; Pilorget, Cedric; Rice, Melissa; Siebach, Kirsten; Stack, Katie; Stolper, Edward; Brunet, Claude; Hipkin, Victoria; Léveillé, Richard; Marchand, Geneviève; Sánchez, Pablo Sobrón; Favot, Laurent; Cody, George; Steele, Andrew; Flückiger, Lorenzo; Lees, David; Nefian, Ara; Martin, Mildred; Gailhanou, Marc; Westall, Frances; Israël, Guy; Agard, Christophe; Baroukh, Julien; Donny, Christophe; Gaboriaud, Alain; Guillemot, Philippe; Lafaille, Vivian; Lorigny, Eric; Paillet, Alexis; Pérez, René; Saccoccio, Muriel; Yana, Charles; Armiens-Aparicio, Carlos; Rodríguez, Javier Caride; Blázquez, Isaías Carrasco; Gómez, Felipe Gómez; Gómez-Elvira, Javier; Hettrich, Sebastian; Malvitte, Alain Lepinette; Jiménez, Mercedes Marín; Martínez-Frías, Jesús; Martín-Soler, Javier; - Torres, F. Javier Martín; Jurado, Antonio Molina; Mora-Sotomayor, Luis; Caro, Guillermo Muñoz; López, Sara Navarro; Peinado-González, Verónica; Pla-García, Jorge; Manfredi, José Antonio Rodriguez; Romeral-Planelló, Julio José; Fuentes, Sara Alejandra Sans; Martinez, Eduardo Sebastian; Redondo, Josefina Torres; Urqui-O'Callaghan, Roser; Mier, María-Paz Zorzano; Chipera, Steve; Lacour, Jean-Luc; Mauchien, Patrick; Sirven, Jean-Baptiste; Manning, Heidi; Fairén, Alberto; Hayes, Alexander; Joseph, Jonathan; Squyres, Steven; Sullivan, Robert; Thomas, Peter; Dupont, Audrey; Lundberg, Angela; Melikechi, Noureddine; Mezzacappa, Alissa; DeMarines, Julia; Grinspoon, David; Reitz, Günther; Prats, Benito; Atlaskin, Evgeny; Genzer, Maria; Harri, Ari-Matti; Haukka, Harri; Kahanpää, Henrik; Kauhanen, Janne; Kemppinen, Osku; Paton, Mark; Polkko, Jouni; Schmidt, Walter; Siili, Tero; Fabre, Cécile; Wray, James; Wilhelm, Mary Beth; Poitrasson, Franck; Patel, Kiran; Gorevan, Stephen; Indyk, Stephen; Paulsen, Gale; Gupta, Sanjeev; Bish, David; Schieber, Juergen; Gondet, Brigitte; Langevin, Yves; Geffroy, Claude; Baratoux, David; Berger, Gilles; Cros, Alain; d’Uston, Claude; Forni, Olivier; Gasnault, Olivier; Lasue, Jérémie; Lee, Qiu-Mei; Maurice, Sylvestre; Meslin, Pierre-Yves; Pallier, Etienne; Parot, Yann; Pinet, Patrick; Schröder, Susanne; Toplis, Mike; Lewin, Éric; Brunner, Will; Heydari, Ezat; Achilles, Cherie; Oehler, Dorothy; Sutter, Brad; Cabane, Michel; Coscia, David; Israël, Guy; Szopa, Cyril; Dromart, Gilles; Robert, François; Sautter, Violaine; Le Mouélic, Stéphane; Mangold, Nicolas; Nachon, Marion; Buch, Arnaud; Stalport, Fabien; Coll, Patrice; François, Pascaline; Raulin, François; Teinturier, Samuel; Cameron, James; Clegg, Sam; Cousin, Agnès; DeLapp, Dorothea; Dingler, Robert; Jackson, Ryan Steele; Johnstone, Stephen; Lanza, Nina; Little, Cynthia; Nelson, Tony; Wiens, Roger C.; Williams, Richard B.; Jones, Andrea; Kirkland, Laurel; Treiman, Allan; Baker, Burt; Cantor, Bruce; Caplinger, Michael; Davis, Scott; Duston, Brian; Edgett, Kenneth; Fay, Donald; Hardgrove, Craig; Harker, David; Herrera, Paul; Jensen, Elsa; Kennedy, Megan R.; Krezoski, Gillian; Krysak, Daniel; Lipkaman, Leslie; Malin, Michael; McCartney, Elaina; McNair, Sean; Nixon, Brian; Posiolova, Liliya; Ravine, Michael; Salamon, Andrew; Saper, Lee; Stoiber, Kevin; Supulver, Kimberley; Van Beek, Jason; Van Beek, Tessa; Zimdar, Robert; French, Katherine Louise; Iagnemma, Karl; Miller, Kristen; Summons, Roger; Goesmann, Fred; Goetz, Walter; Hviid, Stubbe; Johnson, Micah; Lefavor, Matthew; Lyness, Eric; Breves, Elly; Dyar, M. Darby; Fassett, Caleb; Blake, David F.; Bristow, Thomas; DesMarais, David; Edwards, Laurence; Haberle, Robert; Hoehler, Tori; Hollingsworth, Jeff; Kahre, Melinda; Keely, Leslie; McKay, Christopher; Wilhelm, Mary Beth; Bleacher, Lora; Brinckerhoff, William; Choi, David; Conrad, Pamela; Dworkin, Jason P.; Eigenbrode, Jennifer; Floyd, Melissa; Freissinet, Caroline; Garvin, James; Glavin, Daniel; Harpold, Daniel; Jones, Andrea; Mahaffy, Paul; Martin, David K.; McAdam, Amy; Pavlov, Alexander; Raaen, Eric; Smith, Michael D.; Stern, Jennifer; Tan, Florence; Trainer, Melissa; Meyer, Michael; Posner, Arik; Voytek, Mary; Anderson, Robert C; Aubrey, Andrew; Beegle, Luther W.; Behar, Alberto; Blaney, Diana; Brinza, David; Calef, Fred; Christensen, Lance; Crisp, Joy A.; DeFlores, Lauren; Ehlmann, Bethany; Feldman, Jason; Feldman, Sabrina; Flesch, Gregory; Hurowitz, Joel; Jun, Insoo; Keymeulen, Didier; Maki, Justin; Mischna, Michael; Morookian, John Michael; Parker, Timothy; Pavri, Betina; Schoppers, Marcel; Sengstacken, Aaron; Simmonds, John J.; Spanovich, Nicole; Juarez, Manuel de la Torre; Vasavada, Ashwin R.; Webster, Christopher R.; Yen, Albert; Archer, Paul Douglas; Cucinotta, Francis; Jones, John H.; Ming, Douglas; Morris, Richard V.; Niles, Paul; Rampe, Elizabeth; Nolan, Thomas; Fisk, Martin; Radziemski, Leon; Barraclough, Bruce; Bender, Steve; Berman, Daniel; Dobrea, Eldar Noe; Tokar, Robert; Vaniman, David; Williams, Rebecca M. E.; Yingst, Aileen; Lewis, Kevin; Leshin, Laurie; Cleghorn, Timothy; Huntress, Wesley; Manhès, Gérard; Hudgins, Judy; Olson, Timothy; Stewart, Noel; Sarrazin, Philippe; Grant, John; Vicenzi, Edward; Wilson, Sharon A.; Bullock, Mark; Ehresmann, Bent; Hamilton, Victoria; Hassler, Donald; Peterson, Joseph; Rafkin, Scot; Zeitlin, Cary; Fedosov, Fedor; Golovin, Dmitry; Karpushkina, Natalya; Kozyrev, Alexander; Litvak, Maxim; Malakhov, Alexey; Mitrofanov, Igor; Mokrousov, Maxim; Nikiforov, Sergey; Prokhorov, Vasily; Sanin, Anton; Tretyakov, Vladislav; Varenikov, Alexey; Vostrukhin, Andrey; Kuzmin, Ruslan; Clark, Benton; Wolff, Michael; McLennan, Scott; Botta, Oliver; Drake, Darrell; Bean, Keri; Lemmon, Mark; Schwenzer, Susanne P.; Anderson, Ryan B.; Herkenhoff, Kenneth; Lee, Ella Mae; Sucharski, Robert; Hernández, Miguel Ángel de Pablo; Ávalos, Juan José Blanco; Ramos, Miguel; Kim, Myung-Hee; Malespin, Charles; Plante, Ianik; Muller, Jan-Peter; Navarro-González, Rafael; Ewing, Ryan; Boynton, William; Downs, Robert; Fitzgibbon, Mike; Harshman, Karl; Morrison, Shaunna; Dietrich, William; Kortmann, Onno; Palucis, Marisa; Sumner, Dawn Y.; Williams, Amy; Lugmair, Günter; Wilson, Michael A.; Rubin, David; Jakosky, Bruce; Balic-Zunic, Tonci; Frydenvang, Jens; Jensen, Jaqueline Kløvgaard; Kinch, Kjartan; Koefoed, Asmus; Madsen, Morten Bo; Stipp, Susan Louise Svane; Boyd, Nick; Campbell, John L.; Gellert, Ralf; Perrett, Glynis; Pradler, Irina; VanBommel, Scott; Jacob, Samantha; Owen, Tobias; Rowland, Scott; Atlaskin, Evgeny; Savijärvi, Hannu; Boehm, Eckart; Böttcher, Stephan; Burmeister, Sönke; Guo, Jingnan; Köhler, Jan; García, César Martín; Mueller-Mellin, Reinhold; Wimmer-Schweingruber, Robert; Bridges, John C.; McConnochie, Timothy; Benna, Mehdi; Franz, Heather; Bower, Hannah; Brunner, Anna; Blau, Hannah; Boucher, Thomas; Carmosino, Marco; Atreya, Sushil; Elliott, Harvey; Halleaux, Douglas; Rennó, Nilton; Wong, Michael; Pepin, Robert; Elliott, Beverley; Spray, John; Thompson, Lucy; Gordon, Suzanne; Newsom, Horton; Ollila, Ann; Williams, Joshua; Vasconcelos, Paulo; Bentz, Jennifer; Nealson, Kenneth; Popa, Radu; Kah, Linda C.; Moersch, Jeffrey; Tate, Christopher; Day, Mackenzie; Kocurek, Gary; Hallet, Bernard; Sletten, Ronald; Francis, Raymond; McCullough, Emily; Cloutis, Ed; ten Kate, Inge Loes; Kuzmin, Ruslan; Arvidson, Raymond; Fraeman, Abigail; Scholes, Daniel; Slavney, Susan; Stein, Thomas; Ward, Jennifer; Berger, Jeffrey; Moores, John E.

2015-01-01

The Sample Analysis at Mars (SAM) investigation on the Mars Science Laboratory (MSL) Curiosity rover has detected oxidized nitrogen-bearing compounds during pyrolysis of scooped aeolian sediments and drilled sedimentary deposits within Gale crater. Total N concentrations ranged from 20 to 250 nmol N per sample. After subtraction of known N sources in SAM, our results support the equivalent of 110–300 ppm of nitrate in the Rocknest (RN) aeolian samples, and 70–260 and 330–1,100 ppm nitrate in John Klein (JK) and Cumberland (CB) mudstone deposits, respectively. Discovery of indigenous martian nitrogen in Mars surface materials has important implications for habitability and, specifically, for the potential evolution of a nitrogen cycle at some point in martian history. The detection of nitrate in both wind-drifted fines (RN) and in mudstone (JK, CB) is likely a result of N2 fixation to nitrate generated by thermal shock from impact or volcanic plume lightning on ancient Mars. Fixed nitrogen could have facilitated the development of a primitive nitrogen cycle on the surface of ancient Mars, potentially providing a biochemically accessible source of nitrogen. PMID:25831544

Evidence for indigenous nitrogen in sedimentary and aeolian deposits from the Curiosity rover investigations at Gale crater, Mars.

Science.gov (United States)

Stern, Jennifer C; Sutter, Brad; Freissinet, Caroline; Navarro-González, Rafael; McKay, Christopher P; Archer, P Douglas; Buch, Arnaud; Brunner, Anna E; Coll, Patrice; Eigenbrode, Jennifer L; Fairen, Alberto G; Franz, Heather B; Glavin, Daniel P; Kashyap, Srishti; McAdam, Amy C; Ming, Douglas W; Steele, Andrew; Szopa, Cyril; Wray, James J; Martín-Torres, F Javier; Zorzano, Maria-Paz; Conrad, Pamela G; Mahaffy, Paul R

2015-04-07

The Sample Analysis at Mars (SAM) investigation on the Mars Science Laboratory (MSL) Curiosity rover has detected oxidized nitrogen-bearing compounds during pyrolysis of scooped aeolian sediments and drilled sedimentary deposits within Gale crater. Total N concentrations ranged from 20 to 250 nmol N per sample. After subtraction of known N sources in SAM, our results support the equivalent of 110-300 ppm of nitrate in the Rocknest (RN) aeolian samples, and 70-260 and 330-1,100 ppm nitrate in John Klein (JK) and Cumberland (CB) mudstone deposits, respectively. Discovery of indigenous martian nitrogen in Mars surface materials has important implications for habitability and, specifically, for the potential evolution of a nitrogen cycle at some point in martian history. The detection of nitrate in both wind-drifted fines (RN) and in mudstone (JK, CB) is likely a result of N2 fixation to nitrate generated by thermal shock from impact or volcanic plume lightning on ancient Mars. Fixed nitrogen could have facilitated the development of a primitive nitrogen cycle on the surface of ancient Mars, potentially providing a biochemically accessible source of nitrogen.

Nitrate accumulation and leaching potential reduced by coupled water and nitrogen management in the Huang-Huai-Hai Plain.

Science.gov (United States)

Huang, Ping; Zhang, Jiabao; Zhu, Anning; Li, Xiaopeng; Ma, Donghao; Xin, Xiuli; Zhang, Congzhi; Wu, Shengjun; Garland, Gina; Pereira, Engil Isadora Pujol

2018-01-01

Irrigation and nitrogen (N) fertilization in excess of crop requirements are responsible for substantial nitrate accumulation in the soil profile and contamination of groundwater by nitrate leaching during intensive agricultural production. In this on-farm field trial, we compared 16 different water and N treatments on nitrate accumulation and its distribution in the soil profile (0-180cm), nitrate leaching potential, and groundwater nitrate concentration within a summer-maize (Zea mays L.) and winter-wheat (Triticum aestivum L.) rotation system in the Huang-Huai-Hai Plain over five cropping cycles (2006-2010). The results indicated that nitrate remaining in the soil profile after crop harvest and nitrate concentration of soil solutions at two depths (80cm and 180cm) declined with increasing irrigation amounts and increased greatly with increasing N application rates, especially for seasonal N application rates higher than 190kgNha -1 . During the experimental period, continuous torrential rainfall was the main cause for nitrate leaching beyond the root zone (180cm), which could pose potential risks for contamination of groundwater. Nitrate concentration of groundwater varied from 0.2 to 2.9mgL -1 , which was lower than the limit of 10mgL -1 as the maximum safe level for drinking water. In view of the balance between grain production and environmental consequences, seasonal N application rates of 190kgNha -1 and 150kgNha -1 were recommended for winter wheat and summer maize, respectively. Irrigation to the field capacity of 0-40cm and 0-60cm soil depth could be appropriate for maize and wheat, respectively. Therefore, taking grain yields, mineral N accumulation in the soil profile, nitrate leaching potential, and groundwater quality into account, coupled water and N management could provide an opportunity to promote grain production while reducing negative environmental impacts in this region. Copyright © 2017 Elsevier B.V. All rights reserved.

Enrichment of anaerobic nitrate-dependent methanotrophic ?Candidatus Methanoperedens nitroreducens? archaea from an Italian paddy field soil

OpenAIRE

Vaksmaa, Annika; Guerrero-Cruz, Simon; van Alen, Theo A.; Cremers, Geert; Ettwig, Katharina F.; L?ke, Claudia; Jetten, Mike S. M.

2017-01-01

Paddy fields are a significant source of methane and contribute up to 20% of total methane emissions from wetland ecosystems. These inundated, anoxic soils featuring abundant nitrogen compounds and methane are an ideal niche for nitrate-dependent anaerobic methanotrophs. After 2?years of enrichment with a continuous supply of methane and nitrate as the sole electron donor and acceptor, a stable enrichment dominated by ?Candidatus Methanoperedens nitroreducens? archaea and ?Candidatus Methylom...

Nitrogenous air pollutants: Chemical and biological implications

International Nuclear Information System (INIS)

Grosjean, D.

1979-01-01

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

EFFECT OF NITROGEN FERTILIZATION ON YIELD AND QUALITY OF WATERMELON, CV. TOP GUN

OpenAIRE

NOWAKI, RODRIGO HIYOSHI DALMAZZO; CECÍLIO FILHO, ARTHUR BERNARDES; FARIA, ROGÉRIO TEIXEIRA DE; WAMSER, ANDERSON FERNANDO; CORTEZ, JUAN WALDIR MENDONZA

2017-01-01

ABSTRACT Nitrogen (N) is the second most important nutrient required by watermelons that can limit their growth and affect fruit quality when deficient. We evaluated the soil (N-nitrate) and foliar N contents and soluble-solid content of the watermelon 'Top Gun' in Brazil at six rates of N fertilization (0, 50, 100, 150, 200 and 250 kg ha-1). N-nitrate and foliar N levels increased linearly with rate. Number of total and marketable fruit, weight of total and marketable fruit and total and mar...

EFFECT OF NITROGEN FERTILIZATION ON YIELD AND QUALITY OF WATERMELON, CV. TOP GUN

OpenAIRE

RODRIGO HIYOSHI DALMAZZO NOWAKI; ARTHUR BERNARDES CECÍLIO FILHO; ROGÉRIO TEIXEIRA DE FARIA; ANDERSON FERNANDO WAMSER; JUAN WALDIR MENDONZA CORTEZ

2017-01-01

Nitrogen (N) is the second most important nutrient required by watermelons that can limit their growth and affect fruit quality when deficient. We evaluated the soil (N-nitrate) and foliar N contents and soluble-solid content of the watermelon 'Top Gun' in Brazil at six rates of N fertilization (0, 50, 100, 150, 200 and 250 kg ha-1). N-nitrate and foliar N levels increased linearly with rate. Number of total and marketable fruit, weight of total and marketable fruit and total and marketable y...

Effect of irrigation and fertilization on the distribution and fate of nitrogen in greenhouse tomato (solanum lycopersicum l.)

International Nuclear Information System (INIS)

Wang, X.; Xing, Y.

2017-01-01

A greenhouse experiment using tomato (Solanum lycopersicum L., cv. 'Jinpeng 10') was conducted to investigate the fate and transport of nitrogen using different methods of irrigation and fertilization. Three treatments were designed with two irrigation methods (drip irrigation and furrow irrigation) and two fertilizer application methods (fertigation and conventional fertilization). Tomato fruit yield and biomass in the fertigation treatment were significantly higher than those in the conventional fertilization treatment. The highest total uptake of nitrogen by tomato was obtained with drip fertigation and increased significantly in the conventional fertilization and CK treatments. With an increase in nitrate uptake by the fruit, the uptake of the leaf nitrogen also increased in both years of the study. The distribution of the soil nitrate-N concentration tended to be symmetrical along the center of the emitter for drip irrigation and the furrows. The nitrate-N concentration in the CK treatment was 2.85-fold higher than that in the drip fertigation treatment. The proportion of nitrogen uptake of the total nitrogen input varied from 25.38% and 53.73% in two consecutive years, and the residual nitrogen in the fertigation treatment was 48.20% and 44.64% lower than that in the CK treatment in the same two respective years. (author)

Determination of the total nitrate content of thorium nitrate solution with a selective electrode

International Nuclear Information System (INIS)

Wirkner, F.M.

1979-01-01

The nitrate content of thorium nitrate solutions is determined with a liquid membrane nitrate selective electrode utilizing the known addition method in 0.1 M potassium fluoride medium as ionic strength adjustor. It is studied the influence of pH and the presence of chloride, sulphate, phosphate, meta-silicate, thorium, rare earths, iron, titanium, uranium and zirconium at the same concentrations as for the aqueous feed solutions in the thorium purification process. The method is tested in synthetic samples and in samples proceeding from nitric dissolutions of thorium hidroxide and thorium oxicarbonate utilized as thorium concentrates to be purified [pt

Chlorophyll meter reading and total nitrogen content applied as ...

African Journals Online (AJOL)

Ana Mascarello

The present study was aimed to assess the relationship between the reading of the chlorophyll meter and the total nitrogen (N) content ... devices to measure chlorophyll index (SPAD) and N content in the leaf. The nitrogen levels were found ... absorption of other nutrients and the production of carbohydrates. The methods ...

Effects of elevated root zone CO2 and air temperature on photosynthetic gas exchange, nitrate uptake, and total reduced nitrogen content in aeroponically grown lettuce plants.

Science.gov (United States)

He, Jie; Austin, Paul T; Lee, Sing Kong

2010-09-01

Effects of elevated root zone (RZ) CO(2) and air temperature on photosynthesis, productivity, nitrate (NO(3)(-)), and total reduced nitrogen (N) content in aeroponically grown lettuce plants were studied. Three weeks after transplanting, four different RZ [CO(2)] concentrations [ambient (360 ppm) and elevated concentrations of 2000, 10,000, and 50,000 ppm] were imposed on plants grown at two air temperature regimes of 28 degrees C/22 degrees C (day/night) and 36 degrees C/30 degrees C. Photosynthetic CO(2) assimilation (A) and stomatal conductance (g(s)) increased with increasing photosynthetically active radiation (PAR). When grown at 28 degrees C/22 degrees C, all plants accumulated more biomass than at 36 degrees C/30 degrees C. When measured under a PAR >or=600 micromol m(-2) s(-1), elevated RZ [CO(2)] resulted in significantly higher A, lower g(s), and higher midday leaf relative water content in all plants. Under elevated RZ [CO(2)], the increase of biomass was greater in roots than in shoots, causing a lower shoot/root ratio. The percentage increase in growth under elevated RZ [CO(2)] was greater at 36 degrees C/30 degrees C although the total biomass was higher at 28 degrees C/22 degrees C. NO(3)(-) and total reduced N concentrations of shoot and root were significantly higher in all plants under elevated RZ [CO(2)] than under ambient RZ [CO(2)] of 360 ppm at both temperature regimes. At each RZ [CO(2)], NO(3)(-) and total reduced N concentration of shoots were greater at 28 degrees C/22 degrees C than at 36 degrees C/30 degrees C. At all RZ [CO(2)], roots of plants at 36 degrees C/30 degrees C had significantly higher NO(3)(-) and total reduced N concentrations than at 28 degrees C/22 degrees C. Since increased RZ [CO(2)] caused partial stomatal closure, maximal A and maximal g(s) were negatively correlated, with a unique relationship for each air temperature. However, across all RZ [CO(2)] and temperature treatments, there was a close correlation between

Effect of organic enrichment and thermal regime on denitrification and dissimilatory nitrate reduction to ammonium (DNRA) in hypolimnetic sediments of two lowland lakes.

Science.gov (United States)

Nizzoli, Daniele; Carraro, Elisa; Nigro, Valentina; Viaroli, Pierluigi

2010-05-01

We analyzed benthic fluxes of inorganic nitrogen, denitrification and dissimilatory nitrate reduction to ammonium (DNRA) rates in hypolimnetic sediments of lowland lakes. Two neighbouring mesotrophic (Ca' Stanga; CS) and hypertrophic (Lago Verde; LV) lakes, which originated from sand and gravel mining, were considered. Lakes are affected by high nitrate loads (0.2-0.7 mM) and different organic loads. Oxygen consumption, dissolved inorganic carbon, methane and nitrogen fluxes, denitrification and DNRA were measured under summer thermal stratification and late winter overturn. Hypolimnetic sediments of CS were a net sink of dissolved inorganic nitrogen (-3.5 to -4.7 mmol m(-2)d(-1)) in both seasons due to high nitrate consumption. On the contrary, LV sediments turned from being a net sink during winter overturn (-3.5 mmol m(-2)d(-1)) to a net source of dissolved inorganic nitrogen under summer conditions (8.1 mmol m(-2)d(-1)), when significant ammonium regeneration was measured at the water-sediment interface. Benthic denitrification (0.7-4.1 mmol m(-2)d(-1)) accounted for up to 84-97% of total NO(3)(-) reduction and from 2 to 30% of carbon mineralization. It was mainly fuelled by water column nitrate. In CS, denitrification rates were similar in winter and in summer, while in LV summer rates were 4 times lower. DNRA rates were generally low in both lakes (0.07-0.12 mmol m(-2)d(-1)). An appreciable contribution of DNRA was only detected in the more reducing sediments of LV in summer (15% of total NO(3)(-) reduction), while during the same period only 3% of reduced NO(3)(-) was recycled into ammonium in CS. Under summer stratification benthic denitrification was mainly nitrate-limited due to nitrate depletion in hypolimnetic waters and parallel oxygen depletion, hampering nitrification. Organic enrichment and reducing conditions in the hypolimnetic sediment shifted nitrate reduction towards more pronounced DNRA, which resulted in the inorganic nitrogen recycling and

Comparative evaluation of nitrate removal technologies

International Nuclear Information System (INIS)

Darbi, A.; Viraraghavan, T.; Butler, R.; Corkal, D.

2002-01-01

Due to the extensive application of artificial nitrogen-based fertilizers and animal manure on land, many water agencies face problems of increasing concentrations of nitrate in groundwater. The contamination of groundwater by nitrate may pose a significant public health problem. The threat of methemoglobinemia is well documented and reflected in the U.S. drinking water standard of 10 mg/L as nitrate-nitrogen. Approximately 45% of Saskatchewan's population use groundwater for drinking purposes, out of which, approximately 23% (230,000) are rural residents. The water used is made available from over 48,000 privately owned wells in regions where there is an extensive application of chemical fertilizers. Biological denitrification, ion exchange and reveres osmosis (RO) processes were selected for further study. Field studies were conducted on these processes. The sulfur/limestone autotrophic denitrification (SLAD) process was selected to achieve biological removal of nitrate from groundwater. The feasibility of the system was evaluated under anaerobic conditions. An ion exchange study was conducted using Ionac A554 which is strong anion exchange resins. In the case of groundwater containing low sulfate concentrations, A554 offered high nitrate removal. However, the disposal of regenerant brine can be a problem. A reverse osmosis unit with Filmtec membrane elements (FT30-Element Family) was used in the study on nitrate removal. The unit effluent average nitrate concentration was less than the maximum allowable concentration. (author)

Method of producing thin cellulose nitrate film

International Nuclear Information System (INIS)

Lupica, S.B.

1975-01-01

An improved method for forming a thin nitrocellulose film of reproducible thickness is described. The film is a cellulose nitrate film, 10 to 20 microns in thickness, cast from a solution of cellulose nitrate in tetrahydrofuran, said solution containing from 7 to 15 percent, by weight, of dioctyl phthalate, said cellulose nitrate having a nitrogen content of from 10 to 13 percent

Recent studies of the ocean nitrogen cycle

Science.gov (United States)

Eppley, R. W.

1984-01-01

The nitrogen cycle in the ocean is dominated by the activities of organisms. External nitrogen inputs from land and from the atmosphere are small compared with rates of consumption and production by organisms and with rates of internal rearrangements of nitrogen pools within the ocean. The chief reservoirs of nitrogen are, in decreasing order of size: nitrogen in sediments, dissolved N2, nitrate, dissolved organic nitrogen (DON), particulate organic nitrogen (PON) (mostly organisms and their by-products). The biogenic fluxes of nitrogen were reviewed. The rate of PON decomposition in the surface layer must be comparable to the rate of ammonium consumption; and at the same time the nitrate consumption rate will be similar to the rates of: (1) sinking of PON out of the surface layer and its decompositon at depth, (2) the rate of nitrification at depth, and (3) the rate of nitrate return to the surface layer by upwelling.

Chlorophyll meter reading and total nitrogen content applied as ...

African Journals Online (AJOL)

The present study was aimed to assess the relationship between the reading of the chlorophyll meter and the total nitrogen (N) content in the leaf in different parts of the crambe plant, depending on the doses of nitrogen applied to the canopy. Randomized block design in a split plot experimental design was used. The plots ...

Nitrogen economics of root foraging: transitive closure of the nitrate-cytokinin relay and distinct systemic signaling for N supply vs. demand.

Science.gov (United States)

Ruffel, Sandrine; Krouk, Gabriel; Ristova, Daniela; Shasha, Dennis; Birnbaum, Kenneth D; Coruzzi, Gloria M

2011-11-08

As sessile organisms, root plasticity enables plants to forage for and acquire nutrients in a fluctuating underground environment. Here, we use genetic and genomic approaches in a "split-root" framework--in which physically isolated root systems of the same plant are challenged with different nitrogen (N) environments--to investigate how systemic signaling affects genome-wide reprogramming and root development. The integration of transcriptome and root phenotypes enables us to identify distinct mechanisms underlying "N economy" (i.e., N supply and demand) of plants as a system. Under nitrate-limited conditions, plant roots adopt an "active-foraging strategy", characterized by lateral root outgrowth and a shared pattern of transcriptome reprogramming, in response to either local or distal nitrate deprivation. By contrast, in nitrate-replete conditions, plant roots adopt a "dormant strategy", characterized by a repression of lateral root outgrowth and a shared pattern of transcriptome reprogramming, in response to either local or distal nitrate supply. Sentinel genes responding to systemic N signaling identified by genome-wide comparisons of heterogeneous vs. homogeneous split-root N treatments were used to probe systemic N responses in Arabidopsis mutants impaired in nitrate reduction and hormone synthesis and also in decapitated plants. This combined analysis identified genetically distinct systemic signaling underlying plant N economy: (i) N supply, corresponding to a long-distance systemic signaling triggered by nitrate sensing; and (ii) N demand, experimental support for the transitive closure of a previously inferred nitrate-cytokinin shoot-root relay system that reports the nitrate demand of the whole plant, promoting a compensatory root growth in nitrate-rich patches of heterogeneous soil.

Characterization of a catalyst-based conversion technique to measure total particulate nitrogen and organic carbon and comparison to a particle mass measurement instrument

Science.gov (United States)

Stockwell, Chelsea E.; Kupc, Agnieszka; Witkowski, Bartłomiej; Talukdar, Ranajit K.; Liu, Yong; Selimovic, Vanessa; Zarzana, Kyle J.; Sekimoto, Kanako; Warneke, Carsten; Washenfelder, Rebecca A.; Yokelson, Robert J.; Middlebrook, Ann M.; Roberts, James M.

2018-05-01

The chemical composition of aerosol particles is a key aspect in determining their impact on the environment. For example, nitrogen-containing particles impact atmospheric chemistry, air quality, and ecological N deposition. Instruments that measure total reactive nitrogen (Nr = all nitrogen compounds except for N2 and N2O) focus on gas-phase nitrogen and very few studies directly discuss the instrument capacity to measure the mass of Nr-containing particles. Here, we investigate the mass quantification of particle-bound nitrogen using a custom Nr system that involves total conversion to nitric oxide (NO) across platinum and molybdenum catalysts followed by NO-O3 chemiluminescence detection. We evaluate the particle conversion of the Nr instrument by comparing to mass-derived concentrations of size-selected and counted ammonium sulfate ((NH4)2SO4), ammonium nitrate (NH4NO3), ammonium chloride (NH4Cl), sodium nitrate (NaNO3), and ammonium oxalate ((NH4)2C2O4) particles determined using instruments that measure particle number and size. These measurements demonstrate Nr-particle conversion across the Nr catalysts that is independent of particle size with 98 ± 10 % efficiency for 100-600 nm particle diameters. We also show efficient conversion of particle-phase organic carbon species to CO2 across the instrument's platinum catalyst followed by a nondispersive infrared (NDIR) CO2 detector. However, the application of this method to the atmosphere presents a challenge due to the small signal above background at high ambient levels of common gas-phase carbon compounds (e.g., CO2). We show the Nr system is an accurate particle mass measurement method and demonstrate its ability to calibrate particle mass measurement instrumentation using single-component, laboratory-generated, Nr-containing particles below 2.5 µm in size. In addition we show agreement with mass measurements of an independently calibrated online particle-into-liquid sampler directly coupled to the

Regional Variability of Agriculturally-Derived Nitrate-Nitrogen in Shallow Groundwater in China, 2004–2014

Directory of Open Access Journals (Sweden)

Jing Li

2018-05-01

Full Text Available Increasing diffuse nitrate loading of groundwater has long been a major environmental and health concern in China, but little is known about the spatial and temporal variability of nitrate concentrations in groundwater at regional scales. The aim of this study was to assess the spatial distribution and variation of nitrate-nitrogen (NO3−-N concentrations in groundwater. We used groundwater quality monitoring data and soil physical characteristics from 21 agro-ecosystems in China for years 2004 to 2014. The results indicated that NO3−-N concentrations were highly variable in shallow groundwater across the landscape. Over the study period, most of the NO3−-N concentrations were below the World Health Organization permissible limit for drinking water (<10 mg N·L. NO3−-N concentrations in groundwater neither significantly increased nor decreased in most agro-ecosystems, but fluctuated with seasons. In addition, groundwater NO3−-N under purple soil (6.81 mg·L−1 and Aeolian sandy soil (6.02 mg·L−1 were significantly higher (p < 0.05 than that under other soil types, and it was medium-high (4.49 mg·L−1 under aquic cinnamon soil. Elevated nitrate concentrations occurred mainly in oasis agricultural areas of northwestern China, where farmlands with coarse-textured soils use flood irrigation. Therefore, arid and semi-arid areas are expected to sustain high NO3−-N concentrations in groundwater. Mitigation strategies can prevent this problem, and include control of N fertilizer input, balanced fertilization, proper rotation system, adoption of improved irrigation methods, and establishment of environmental policies.

NITRATE CONTAMINATION OF GROUND WATER (GW-761)

Science.gov (United States)

The occurrence of nitrate and related compounds in ground water is discussed from the perspectives of its natural as well as anthropogenic origins. A brief explanation of the nitrogen cycle touches on the production as well as utilization of ammonia, nitrite, nitrate, and nitrog...

Evaluation of Approaches for Managing Nitrate Loading from On-Site Wastewater Systems near La Pine, Oregon

Science.gov (United States)

Morgan, David S.; Hinkle, Stephen R.; Weick, Rodney J.

2007-01-01

This report presents the results of a study by the U.S. Geological Survey, done in cooperation with the Oregon Department of Environmental Quality and Deschutes County, to develop a better understanding of the effects of nitrogen from on-site wastewater disposal systems on the quality of ground water near La Pine in southern Deschutes County and northern Klamath County, Oregon. Simulation models were used to test the conceptual understanding of the system and were coupled with optimization methods to develop the Nitrate Loading Management Model, a decision-support tool that can be used to efficiently evaluate alternative approaches for managing nitrate loading from on-site wastewater systems. The conceptual model of the system is based on geologic, hydrologic, and geochemical data collected for this study, as well as previous hydrogeologic and water quality studies and field testing of on-site wastewater systems in the area by other agencies. On-site wastewater systems are the only significant source of anthropogenic nitrogen to shallow ground water in the study area. Between 1960 and 2005 estimated nitrate loading from on-site wastewater systems increased from 3,900 to 91,000 pounds of nitrogen per year. When all remaining lots are developed (in 2019 at current building rates), nitrate loading is projected to reach nearly 150,000 pounds of nitrogen per year. Low recharge rates (2-3 inches per year) and ground-water flow velocities generally have limited the extent of nitrate occurrence to discrete plumes within 20-30 feet of the water table; however, hydraulic-gradient and age data indicate that, given sufficient time and additional loading, nitrate will migrate to depths where many domestic wells currently obtain water. In 2000, nitrate concentrations greater than 4 milligrams nitrogen per liter (mg N/L) were detected in 10 percent of domestic wells sampled by Oregon Department of Environmental Quality. Numerical simulation models were constructed at transect (2

Using Nitrate Isotopes to Distinguish Pathways along which Unprocessed Atmospheric Nitrate is Transported through Forests to Streams

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Sebestyen, S. D.

2013-12-01

Evaluation of natural abundance oxygen and nitrogen isotopes in nitrate has revealed that atmospheric deposition of nitrate to forests sometimes has direct effects on the timing and magnitude of stream nitrate concentrations. Large amounts of unprocessed atmospheric nitrate have sometimes been found in streams during snowmelt and stormflow events. Despite increasing evidence that unprocessed atmospheric nitrate may be transported without biological processing to streams at various times and multiple locations, little has been reported about specific hydrological processes. I synthesized research findings from a number of studies in which nitrate isotopes have been measured over the past decade. Unprocessed nitrate may predominate in surficial soil waters after rainfall and snowmelt events relative to nitrate that originated from nitrification. Although transport to deep groundwater may be important in the most nitrogen saturated catchments, the transport of unprocessed atmospheric nitrate along shallow subsurface flowpaths is likely more important in many moderately N-polluted ecosystems, which predominate in the northeastern USA where most of my study sites are located. The presence of unprocessed atmospheric nitrate in surficial soils was linked to stream nitrate concentrations when large amounts of unprocessed nitrate were occasionally routed along lateral, shallow subsurface flowpaths during stormflow events. During these events, water tables rose to saturate shallow-depth soils. When catchments were drying or dryer, atmospheric nitrate was completely consumed by biological processing as flowpaths shifted from lateral to vertical transport through soils. The source areas of unprocessed atmospheric nitrate were usually limited to soils that were adjacent to streams, with little to no near-surface saturation and transport of unprocessed nitrate from more distal hillslope positions. The occasional large amounts of unprocessed atmospheric nitrate in soil water

Anthropogenic imprints on nitrogen and oxygen isotopic composition of precipitation nitrate in a nitrogen-polluted city in southern China

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Fang, Y. T.; Koba, K.; Wang, X. M.; Wen, D. Z.; Li, J.; Takebayashi, Y.; Liu, X. Y.; Yoh, M.

2011-02-01

Nitric acid (HNO3) or nitrate (NO3-) is the dominant sink for reactive nitrogen oxides (NOx = NO + NO2) in the atmosphere. In many Chinese cities, HNO3 is becoming a significant contributor to acid deposition. In the present study, we measured nitrogen (N) and oxygen (O) isotopic composition of NO3- in 113 precipitation samples collected from Guangzhou City in southern China over a two-year period (2008 and 2009). We attempted to better understand the spatial and seasonal variability of atmospheric NOx sources and the NO3- formation pathways in this N-polluted city in the Pearl River Delta region. The δ15N values of NO3- (versus air N2) ranged from -4.9 to +10.1‰, and averaged +3.9‰ in 2008 and +3.3‰ in 2009. Positive δ15N values were observed throughout the year, indicating the anthropogenic contribution of NOx emissions, particularly from coal combustion. Different seasonal patterns of δ15N-NO3- were observed between 2008 and 2009, which might reflect different human activities associated with the global financial crisis and the intensive preparations for the 16th Asian Games. Nitrate δ18O values (versus Vienna Standard Mean Ocean Water) varied from +33.4 to +86.5‰ (average +65.0‰ and +67.0‰ in 2008 and 2009, respectively), a range being lower than those reported for high latitude and polar areas. Sixteen percent of δ18O values was observed lower than the expected minimum of +55‰ at our study site. This was likely caused by the reaction of NO with peroxy radicals; peroxy radicals can compete with O3 to convert NO to NO2, thereby donate O atoms with much lower δ18O value than that of O3 to atmospheric NO3-. Our results highlight that the influence of human activities on atmospheric chemistry can be recorded by the N and O isotopic composition of atmospheric NO3- in a N-polluted city.

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

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Chen, Wei-Hsiang; Young, Thomas M

2009-07-01

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

Influence of Nitrogen Source on NDMA Formation during Chlorination of Diuron

Science.gov (United States)

Chen, Wei-Hsiang; Young, Thomas M.

2009-01-01

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

Nitrogen nutrition of Salvinia natans: Effects of inorganic nitrogen form on growth, morphology, nitrate reductase activity and uptake kinetics of ammonium and nitrate

DEFF Research Database (Denmark)

Jampeetong, Arunothai; Brix, Hans

2009-01-01

In this study we assessed the growth, morphological responses, and N uptake kinetics of Salvinia natans when supplied with nitrogen as NO3-, NH4+, or both at equimolar concentrations (500 μM). Plants supplied with only NO3- had lower growth rates (0.17 ± 0.01 g g-1 d-1), shorter roots, smaller...... leaves with less chlorophyll than plants supplied with NH4+ alone or in combination with NO3- (RGR = 0.28 ± 0.01 g g-1 d-1). Ammonium was the preferred form of N taken up. The maximal rate of NH4+ uptake (Vmax) was 6-14 times higher than the maximal uptake rate of NO3- and the minimum concentration...... for uptake (Cmin) was lower for NH4+ than for NO3-. Plants supplied with NO3- had elevated nitrate reductase activity (NRA) particularly in the roots showing that NO3- was primarily reduced in the roots, but NRA levels were generally low (NH4...

Sources and chronology of nitrate contamination in spring waters, Suwannee River basin, Florida

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Katz, Brian G.; Hornsby, H.D.; Bohlke, J.K.; Mokray, M.F.

1999-01-01

A multi-tracer approach, which consisted of analyzing water samples for n aturally occurring chemical and isotopic indicators, was used to better understand sources and chronology of nitrate contamination in spring wate rs discharging to the Suwannee and Santa Fe Rivers in northern Florida. Dur ing 1997 and 1998, as part of a cooperative study between the Suwannee River Water Management District and the U.S. Geological Survey, water samples were collected and analyzed from 24 springs and two wells for major ions, nutrients, dissolved organic carbon, and selected environmental isotopes [18O/16O, D/H, 13C/12C, 15N/14N]. To better understand when nitrate entered the ground-water system, water samples were analyzed for chlorofluorocarbons (CFCs; CCl3F, CCl2F2, and C2Cl3F3) and tritium (3H); in this way, the apparent ages and residence times of spring waters and water from shallow zones in the Upper Floridan aquifer were determined. In addition to information obtained from the use of isotopic and other chemical tracers, information on changes in land-use activities in the basin during 1954-97 were used to estimate nitrogen inputs from nonpoint sources for five counties in the basin. Changes in nitrate concentrations in spring waters with time were compared with estimated nitrogen inputs for Lafayette and Suwannee Counties. Agricultural activities [cropland farming, animal farming operations (beef and dairy cows, poultry, and swine)] along with atmospheric deposition have contributed large quantities of nitrogen to ground water in the Suwannee River Basin in northern Florida. Changes in agricultural land use during the past 40 years in Alachua, Columbia, Gilchrist, Lafayette, and Suwannee Counties have contributed variable amounts of nitrogen to the ground-water system. During 1955-97, total estimated nitrogen from all nonpoint sources (fertilizers, animal wastes, atmospheric deposition, and septic tanks) increased continuously in Gilchrist and Lafayette Counties. In

Deposition of reactive nitrogen during the Rocky Mountain Airborne Nitrogen and Sulfur (RoMANS) study

International Nuclear Information System (INIS)

Beem, Katherine B.; Raja, Suresh; Schwandner, Florian M.; Taylor, Courtney; Lee, Taehyoung; Sullivan, Amy P.; Carrico, Christian M.; McMeeking, Gavin R.; Day, Derek; Levin, Ezra; Hand, Jenny; Kreidenweis, Sonia M.; Schichtel, Bret; Malm, William C.; Collett, Jeffrey L.

2010-01-01

Increases in reactive nitrogen deposition are a growing concern in the U.S. Rocky Mountain west. The Rocky Mountain Airborne Nitrogen and Sulfur (RoMANS) study was designed to improve understanding of the species and pathways that contribute to nitrogen deposition in Rocky Mountain National Park (RMNP). During two 5-week field campaigns in spring and summer of 2006, the largest contributor to reactive nitrogen deposition in RMNP was found to be wet deposition of ammonium (34% spring and summer), followed by wet deposition of nitrate (24% spring, 28% summer). The third and fourth most important reactive nitrogen deposition pathways were found to be wet deposition of organic nitrogen (17%, 12%) and dry deposition of ammonia (14%, 16%), neither of which is routinely measured by air quality/deposition networks operating in the region. Total reactive nitrogen deposition during the spring campaign was determined to be 0.45 kg ha -1 and more than doubled to 0.95 kg ha -1 during the summer campaign. - The reactive nitrogen deposition budget for Rocky Mountain National Park.

CO2 enrichment inhibits shoot nitrate assimilation in C3 but not C4 plants and slows growth under nitrate in C3 plants.

Science.gov (United States)

Bloom, Arnold J; Asensio, Jose Salvador Rubaio; Randall, Lesley; Rachmilevitch, Shimon; Cousins, Asaph B; Carlisle, Eli A

2012-02-01

The CO2 concentration in Earth's atmosphere may double during this century. Plant responses to such an increase depend strongly on their nitrogen status, but the reasons have been uncertain. Here, we assessed shoot nitrate assimilation into amino acids via the shift in shoot CO2 and O2 fluxes when plants received nitrate instead of ammonium as a nitrogen source (deltaAQ). Shoot nitrate assimilation became negligible with increasing CO2 in a taxonomically diverse group of eight C3 plant species, was relatively insensitive to CO2 in three C4 species, and showed an intermediate sensitivity in two C3-C4 intermediate species. We then examined the influence of CO2 level and ammonium vs. nitrate nutrition on growth, assessed in terms of changes in fresh mass, of several C3 species and a Crassulacean acid metabolism (CAM) species. Elevated CO2 (720 micromol CO2/mol of all gases present) stimulated growth or had no effect in the five C3 species tested when they received ammonium as a nitrogen source but inhibited growth or had no effect if they received nitrate. Under nitrate, two C3 species grew faster at sub-ambient (approximately 310 micromol/mol) than elevated CO2. A CAM species grew faster at ambient than elevated or sub-ambient CO2 under either ammonium or nitrate nutrition. This study establishes that CO2 enrichment inhibits shoot nitrate assimilation in a wide variety of C3 plants and that this phenomenon can have a profound effect on their growth. This indicates that shoot nitrate assimilation provides an important contribution to the nitrate assimilation of an entire C3 plant. Thus, rising CO2 and its effects on shoot nitrate assimilation may influence the distribution of C3 plant species.

[Removal of nitrate from groundwater using permeable reactive barrier].

Science.gov (United States)

Li, Xiu-Li; Yang, Jun-Jun; Lu, Xiao-Xia; Zhang, Shu; Hou, Zhen

2013-03-01

To provide a cost-effective method for the remediation of nitrate-polluted groundwater, column experiments were performed to study the removal of nitrate by permeable reactive barrier filled with fermented mulch and sand (biowall), and the mechanisms and influence factors were explored. The experimental results showed that the environmental condition in the simulated biowall became highly reduced after three days of operation (oxidation-reduction potential was below - 100 mV), which was favorable for the reduction of nitrate. During the 15 days of operation, the removal rate of nitrate nitrogen (NO3(-) -N) by the simulated biowall was 80%-90% (NO3(-)-N was reduced from 20 mg x L(-1) in the inlet water to 1.6 mg x L(-1) in the outlet water); the concentration of nitrite nitrogen (NO2(-) -N) in the outlet water was below 2.5 mg x L(-1); the concentration of ammonium nitrogen (NH4(+) -N) was low in the first two days but increased to about 12 mg x L(-1) since day three. The major mechanisms involved in the removal of nitrate nitrogen were adsorption and biodegradation. When increasing the water flow velocity in the simulated biowall, the removal rate of NO3(-) -N was reduced and the concentration of NH4(+) -N in the outlet water was significantly reduced. A simulated zeolite wall was set up following the simulated biowall and 98% of the NH4(+) -N could be removed from the water.

Properties of aqueous nitrate and nitrite from x-ray absorption spectroscopy

Energy Technology Data Exchange (ETDEWEB)

Smith, Jacob W.; Lam, Royce K.; Saykally, Richard J., E-mail: saykally@berkeley.edu [Department of Chemistry, University of California, Berkeley, California 94720 (United States); Chemical Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720 (United States); Shih, Orion [National Synchrotron Radiation Research Center, Hsinchu 30076, Taiwan (China); Rizzuto, Anthony M. [Department of Chemistry, University of California, Berkeley, California 94720 (United States); Prendergast, David [The Molecular Foundry, Lawrence Berkeley National Laboratory, Berkeley, California 94720 (United States)

2015-08-28

Nitrate and nitrite ions are of considerable interest, both for their widespread use in commercial and research contexts and because of their central role in the global nitrogen cycle. The chemistry of atmospheric aerosols, wherein nitrate is abundant, has been found to depend on the interfacial behavior of ionic species. The interfacial behavior of ions is determined largely by their hydration properties; consequently, the study of the hydration and interfacial behavior of nitrate and nitrite comprises a significant field of study. In this work, we describe the study of aqueous solutions of sodium nitrate and nitrite via X-ray absorption spectroscopy (XAS), interpreted in light of first-principles density functional theory electronic structure calculations. Experimental and calculated spectra of the nitrogen K-edge XA spectra of bulk solutions exhibit a large 3.7 eV shift between the XA spectra of nitrate and nitrite resulting from greater stabilization of the nitrogen 1s energy level in nitrate. A similar shift is not observed in the oxygen K-edge XA spectra of NO{sub 3}{sup −} and NO{sub 2}{sup −}. The hydration properties of nitrate and nitrite are found to be similar, with both anions exhibiting a similar propensity towards ion pairing.

Influence of temperature upon the mobilization of nitrogen in peat

Directory of Open Access Journals (Sweden)

Armi Kaila

1953-01-01

Full Text Available The preliminary experiments the results of which are recorded in the present paper, have been carried out in order to obtain some information on the microbiological and chemical mobilization of peat nitrogen at various temperatures. In the incubation experiment at 5°, 20°, 35°, 50°, and 65CC the accumulation of ammonia nitrogen increased with a rising temperature except in the limed series where a minimum was found at 20°. The maximum of nitrate-nitrogen lay at 20 in both the series. The amount of nitrite-nitrogen was almost negligible in all the samples. The mineral nitrogen in the samples incubated at 50° and 65° represented 10—20 % of the total nitrogen. Thus, the organic nitrogen in peat soils can be mobilized to a marked extent, if the conditions are favourable. Accumulation of mineral nitrogen could be stated also at the lower temperatures where the reutilization of released nitrogen in the synthesis of new microbial substance is always more intensive than in the range of thermophilic organisms. Even at 5° a release of nitrogen was noticable. In these experiments liming did not show any beneficial effect upon the accumulation of mineral nitrogen, on the contrary, the values for total nitrogen and ammonia nitrogen were lower in the limed series. The nitrate formation was generally somewhat higher in the limed samples than in the corresponding unlimed ones. It was supposed that the considerable increase in the ammonia content of the samples incubated at 50° and 65° was partly due to purely chemical transformations, since the mere heating of moist samples at 75° for two hours brought about a marked accumulation of ammonia nitrogen. The treatment with dry heat was less effective except when the temperature was raised to 200° in which case a carbonization of the peat took place. The losses of organic matter and of total nitrogen due to the heating were almost negligible at the temperatures below 150°. At 150° and at 200�

Can nitrate contaminated groundwater be remediated by optimizing flood irrigation rate with high nitrate water in a desert oasis using the WHCNS model?

Science.gov (United States)

Liang, Hao; Qi, Zhiming; Hu, Kelin; Prasher, Shiv O; Zhang, Yuanpei

2016-10-01

Nitrate contamination of groundwater is an environmental concern in intensively cultivated desert oases where this polluted groundwater is in turn used as a major irrigation water resource. However, nitrate fluxes from root zone to groundwater are difficult to monitor in this complex system. The objectives of this study were to validate and apply the WHCNS (soil Water Heat Carbon Nitrogen Simulator) model to simulate water drainage and nitrate leaching under different irrigation and nitrogen (N) management practices, and to assess the utilization of groundwater nitrate as an approach to remediate nitrate contaminated groundwater while maintain crop yield. A two-year field experiment was conducted in a corn field irrigated with high nitrate groundwater (20 mg N L(-1)) in Alxa, Inner Mongolia, China. The experiment consisted of two irrigation treatments (Istd, standard, 750 mm per season; Icsv, conservation, 570 mm per season) factorially combined with two N fertilization treatments (Nstd, standard, 138 kg ha(-1); Ncsv, conservation, 92 kg ha(-1)). The validated results showed that the WHCNS model simulated values of crop dry matter, yield, soil water content and soil N concentration in soil profile all agreed well with the observed values. Compared to the standard water management (Istd), the simulated drainage and nitrate leaching decreased about 65% and 59%, respectively, under the conservation water management (Icsv). Nearly 55% of input N was lost by leaching under the IstdNstd and IstdNcsv treatments, compared to only 26% under the IcsvNstd and IcsvNcsv treatments. Simulations with more than 240 scenarios combing different levels of irrigation and fertilization indicated that irrigation was the main reason leading to the high risk of nitrate leaching, and the nitrate in irrigation groundwater can be best utilized without corn yield loss when the total irrigation was reduced from the current 750 mm to 491 mm. This reduced irrigation rate facilitated

Adjustment of nitrogen fertilization to the needs of plants and limitations posed by the risk of nitrate accumulation and pollution of the soil and subsoil

Energy Technology Data Exchange (ETDEWEB)

Muller, J C

1980-01-01

In chalky Champagne, nitrogen balance is study to adjust availability to plant response. For this, it is necessary to know some parameters whose measurement is obtained progressively; plants exportation, nitrogen transformations in terms of transport processes in soil system, kinetic of mineralization of soil organic nitrogen, plants residus and agricultural waste waters. Lysimeters with rotation of Champagne (wheat, sugarbeet, potatoes...) are used to measure losses of nitrogen and follow transport of nitrates by mean of soil solution captors. Comparisons with field results, lysimeters results and laboratory experimentations are used to adjust an experimental model. Two examples show: 1) Nitrogen fertilizer requirement for wheat. 2) Possibility of maximum application for agricultural waste waters.

High temperature interaction studies on equimolar nitrate mixture of uranyl nitrate hexahydrate and gadolinium nitrate hexahydrate

International Nuclear Information System (INIS)

Kalekar, Bhupesh B.; Raje, Naina; Reddy, A.V.R.

2015-01-01

Rare earths including gadolinium form a sizeable fraction of the fission products in the nuclear fission of fissile material in the reactor. These fission products can interact with uranium dioxide fuel and can form various compounds which can alter the thermal behavior of the fuel. The mixed oxide formed due to the high temperature interactions of mixture of uranyl nitrate hexahydrate (UNH) and gadolinium nitrate hexahydrate (GdNH) has been studied using thermal and X- ray diffraction techniques. The equimolar mixture of UNH and GdNH was prepared by mixing the weighed amount of individual nitrates and grinding gently with mortar and pestle. Thermogravimetry (TG) measurements were carried out by separately heating 100 mg of mixture and individual nitrates at heating rate of 10°C min -1 using Netzsch thermal analyzer (Model No.: STA 409 PC Luxx) in high purity nitrogen atmosphere with a flow rate of 120 mL min -1 . The XRD measurement was carried out on a Philips X-ray diffractometer (Model PW1710) using nickel-filtered Cu-Kα radiation

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

Science.gov (United States)

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

2017-12-01

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

Nitrate Leaching Management

Science.gov (United States)

Nitrate (NO3) leaching is a significant nitrogen (N) loss process for agriculture that must be managed to minimize NO3 enrichment of groundwater and surface waters. Managing NO3 leaching should involve the application of basic principles of understanding the site’s hydrologic cycle, avoiding excess ...

Biosensors Used for Quantification of Nitrates in Plants

Directory of Open Access Journals (Sweden)

Romero-Galindo Raul

2016-01-01

Full Text Available Nitrogen is essential for the plant because it is used for the production of chlorophyll, proteins, nucleic acids, amino acids, and other cellular compounds; nitrogen is available in two forms: ammonium and nitrate. Several tools have been used to quantify nitrates in plants such as the Kjeldahl method and Dumas combustion digestion; however, they are destructive and long time-consuming methods. To solve these disadvantages, methods such as selective electrodes, optical sensors, reflectometers, and images based sensors have been developed; nonetheless, all these techniques show interference when carrying out measurements. Currently, biosensors based on genetic constructions, based on the response of promoter gene fused to Gene Fluorescent Protein (GFP, are gaining popularity, because they improve the accuracy of measurements of nitrate by avoiding the interference of carriers ion, high salt conditions, and other factors. The present review shows the different methods to quantify the nitrogen in plants; later, a biosensors perspective is presented, mainly focused on biosensors based on organism genetically modified. The review presents a list of promoter and reporter genes that could be used to develop different kind of sensors, and a perspective of sensors to measure quantitatively the nitrogen is presented.

Dual (oxygen and nitrogen) isotopic characterization of the museum archived nitrates from the United States of America, South Africa and Australia.

Science.gov (United States)

Mizota, Chitoshi; Hosono, Takahiro; Matsunaga, Midori; Okumura, Azusa

2018-06-01

Dual (oxygen and nitrogen) isotopic composition of the museum archived nitrates from the United States of America, South Africa and Australia was studied. The analyzed specimens were collected in middle 19th to early 20th centuries, and represent world-wide acquisition of the Smithsonian Institution Natural Museum of Natural History (Washington, D. C., USA) and the Natural History Museum (London, UK). The samples consist of transparent to semi-transparent aggregates of minute nitrate, euhedral crystallites which imply precipitation from percolating fluids under ample space and dry regimes. The major nitrate chemistry is saltpetre (KNO 3 ) with minor nitratine (NaNO 3 ). A binary plot of δ 15 N vs. δ 18 O of almost all nitrates indicates a trend, reflecting microbial origin through nitrification of ammonium. The diagram excludes the contribution of meteoric origin formed by mass-independent, photochemical reaction of NO with ozone in stratosphere. Calculated paleo-ambient fluid compositions responsible for microbial nitrification imply extreme evaporative concentration of relevant fluids under dry climatic regimes in the Northern Cape Province (South Africa) and in the Northern Territory (central Australia), and even throughout the United States of America. The dual isotopic characterization provides direct evidence to the origin of the museum archived nitrates. Copyright © 2017 Elsevier B.V. All rights reserved.

Transformation of nitrogen and distribution of nitrogen-related bacteria in a polluted urban stream.

Science.gov (United States)

Jiao, Y; Jin, W B; Zhao, Q L; Zhang, G D; Yan, Y; Wan, J

2009-01-01

Most researchers focused on either nitrogen species or microbial community for polluted urban stream while ignoring the interaction between them and its effect on nitrogen transformation, which restricted the rational selection of an effective and feasible remediation technology. Taking Buji stream in Shenzhen (China) as target stream, the distribution of nitrogen-related bacteria was investigated by most probable number (MPN) besides analysis of nitrogen species etc. The nitrogen-related bacteria in sediment were 10(2) times richer than those in water. Owing to their faster growth, the MPN of ammonifying bacteria and denitrifying bacteria were 10(5) and 10(2) times higher than those of nitrifying bacteria, respectively. The ammonifying bacteria numbers were significantly related to BOD5 in water, while nitrifying bacteria in sediment correlated well with nitrate in water. Thus, nitrification occurred mainly in sediment surface and was limited by low proportion of nitrifying bacteria. The denitrifying bacteria in sediment had good relationship with BOD5 and nitrite and nitrate in water. Low DO and rich organic compounds were beneficial to denitrification but unfavourable to nitrification. Denitrification was restricted by low nitrite and nitrate concentration. These results could be served as a reference for implementing the remediation scheme of nitrogen polluted urban stream.

Øget indhold af nitrat i foderet til malkekøer reducerer udledningen af metan betydeligt

DEFF Research Database (Denmark)

Lund, Peter; Olijhoek, Dana; Dahl, Regina

2015-01-01

would be a substrate for the formation of methane, is being consumed during the energy-favorable reduction of nitrate to ammonia in the rumen. Nitrite is formed during the reduction of nitrate to ammonium and is a potentially toxic intermediate. Neither acute nor long-term negative effect...... metabolism, and energy loss from the process amounts to 5-7 % of the total feed gross energy. Recent Danish research shows that the addition of nitrate to feed can reduce methane emissions by up to 23 % without feed digestibility being negatively affected. This reduction is due to hydrogen, which otherwise...... of the addition of nitrate on the animal's health could be detected. Surprisingly, addition of nitrate resulted in significant emission of nitrous oxide (N2O), which is a very potent greenhouse gas. This underlines that there is a significant change in the rumen nitrogen metabolism when nitrate is added...

Nitrate and nitrite in biology, nutrition and therapeutics

NARCIS (Netherlands)

Lundberg, J.O.; van Faassen, E.E.H.; Gladwin, M.T.; Ahluwalia, A.; Benjamin, N.

2009-01-01

Inorganic nitrate and nitrite from endogenous or dietary sources are metabolized in vivo to nitric oxide (NO) and other bioactive nitrogen oxides. The nitrate-nitrite-NO pathway is emerging as an important mediator of blood flow regulation, cell signaling, energetics and tissue responses to hypoxia.

Carbon and nitrogen stoichiometry across stream ecosystems

Science.gov (United States)

Wymore, A.; Kaushal, S.; McDowell, W. H.; Kortelainen, P.; Bernhardt, E. S.; Johnes, P.; Dodds, W. K.; Johnson, S.; Brookshire, J.; Spencer, R.; Rodriguez-Cardona, B.; Helton, A. M.; Barnes, R.; Argerich, A.; Haq, S.; Sullivan, P. L.; López-Lloreda, C.; Coble, A. A.; Daley, M.

2017-12-01

Anthropogenic activities are altering carbon and nitrogen concentrations in surface waters globally. The stoichiometry of carbon and nitrogen regulates important watershed biogeochemical cycles; however, controls on carbon and nitrogen ratios in aquatic environments are poorly understood. Here we use a multi-biome and global dataset (tropics to Arctic) of stream water chemistry to assess relationships between dissolved organic carbon (DOC) and nitrate, ammonium and dissolved organic nitrogen (DON), providing a new conceptual framework to consider interactions between DOC and the multiple forms of dissolved nitrogen. We found that across streams the total dissolved nitrogen (TDN) pool is comprised of very little ammonium and as DOC concentrations increase the TDN pool shifts from nitrate to DON dominated. This suggests that in high DOC systems, DON serves as the primary source of nitrogen. At the global scale, DOC and DON are positively correlated (r2 = 0.67) and the average C: N ratio of dissolved organic matter (molar ratio of DOC: DON) across our data set is approximately 31. At the biome and smaller regional scale the relationship between DOC and DON is highly variable (r2 = 0.07 - 0.56) with the strongest relationships found in streams draining the mixed temperate forests of the northeastern United States. DOC: DON relationships also display spatial and temporal variability including latitudinal and seasonal trends, and interactions with land-use. DOC: DON ratios correlated positively with gradients of energy versus nutrient limitation pointing to the ecological role (energy source versus nutrient source) that DON plays with stream ecosystems. Contrary to previous findings we found consistently weak relationships between DON and nitrate which may reflect DON's duality as an energy or nutrient source. Collectively these analyses demonstrate how gradients of DOC drive compositional changes in the TDN pool and reveal a high degree of variability in the C: N ratio

Evaluating the source of streamwater nitrate using d15N and d18O in nitrate in two watersheds in New Hampshire, USA

Science.gov (United States)

Linda H. Pardo; Carol Kendall; Jennifer Pett-Ridge; Cecily C.Y. Chang; Cecily C.Y. Chang

2004-01-01

The natural abundance of nitrogen and oxygen isotopes in nitrate can be a powerful tool for identifying the source of nitrate in streamwater in forested watersheds, because the two main sources of nitrate, atmospheric deposition and microbial nitrification, have distinct d18O values. Using a simple mixing model, we estimated the relative fractions in streamwater...

Spatial assessment of animal manure spreading and groundwater nitrate pollution

Directory of Open Access Journals (Sweden)

Roberta Infascelli

2009-11-01

Full Text Available Nitrate concentration in groundwater has frequently been linked to non-point pollution. At the same time the existence of intensive agriculture and extremely intensive livestock activity increases the potential for nitrate pollution in shallow groundwater. Nitrate used in agriculture could cause adverse effects on human and animal health. In order to evaluate the groundwater nitrate pollution, and how it might evolve in time, it is essential to develop control systems and to improve policies and incentives aimed at controlling the amount of nitrate entering downstream water systems. The province of Caserta in southern Italy is characterized by high levels of animal manure loading. A comparison between manure nitrogen production and nitrate concentration in groundwater was carried out in this area, using geostatistical tools and spatial statistics. The results show a discrepancy between modelling of nitrate leaching and monitoring of the groundwater and, moreover, no spatial correlation between nitrogen production in livestock farms and nitrate concentration in groundwater, suggesting that producers are not following the regulatory procedures for the agronomic use of manure. The methodology developed in this paper could be applied also in other regions in which European Union fertilization plans are not adequately followed.

Association of nitrate, nitrite, and total organic carbon (TOC) in drinking water and gastrointestinal disease.

Science.gov (United States)

Khademikia, Samaneh; Rafiee, Zahra; Amin, Mohammad Mehdi; Poursafa, Parinaz; Mansourian, Marjan; Modaberi, Amir

2013-01-01

We aimed to investigate the amounts of nitrate, nitrite, and total organic carbon (TOC) in two drinking water sources and their relationship with some gastrointestinal diseases. This cross-sectional study was conducted in 2012 in Iran. Two wells located in residential areas were selected for sampling and measuring the TOC, nitrate (NO3(-)), and nitrite (NO2(-)). This water is used for drinking as well as for industrial and agricultural consumption. Nitrate and nitrite concentrations of water samples were analyzed using DR 5000 spectrophotometer. The information of patients was collected from the records of the main referral hospital of the region for gastrointestinal diseases. In both areas under study, the mean water nitrate and nitrite concentrations were higher in July than in other months. The mean TOC concentrations in areas 1 and 2 were 2.29 ± 0.012 and 2.03 ± 0.309, respectively. Pollutant concentration and gastrointestinal disease did not show any significant relationship (P > 0.05). Although we did not document significant association of nitrite, nitrate, and TOC content of water with gastrointestinal diseases, it should be considered that such health hazards may develop over time, and the quality of water content should be controlled to prevent different diseases.

Nitrogen utilization during spring phytoplankton bloom development in the southeast Bering Sea

International Nuclear Information System (INIS)

Sambrotto, R.N.

1983-01-01

Interactions beween a high latitude, continental shelf, spring phytoplankton bloom and water column physics and chemistry were studied using 15 N measured rates of nitrogen uptake. Peak bloom conditions commenced when the mixed layer shallowed and minimized respirational losses. Integrative light-mixing growth models were accurate during early bloom stages. An advection-diffusion model associated peak bloom nitrate uptake with pycnocline mixing rates of 2.1 m d -1 in an 18 m mixed layer. Maximum nitrogen specific uptake rates (hr -1 ), unlike those of carbon, coincided with peak bloom conditions. Although species compositions among peak bloom periods were similar, particulate C/N ratios were not. Apparently, both intercellular factors and prevailing mixing conditions influence specific uptake rates and cell composition. A large proportion of new (nitrate) to total productivity was associated with the dominance of the early bloom forming diatoms in the mixed layer. In the absence of these net plankton the residual nanoplankton dominated community exhibited a greater dependence on regenerated nitrogen. Nitrate uptake averaged 700 mg-at m -2 during the spring bloom and 1 g-at m -2 year -1 . The yearly f factor was 0.40. Nitrogen uptake based carbon productivity was 188 g C m -2 year -1

Assessment of the potential for ammonium nitrate formation and reaction in Tank 241-SY-101

International Nuclear Information System (INIS)

Pederson, L.R.; Bryan, S.A.

1994-08-01

Two principal scenarios by which ammonium nitrate may be formed were considered: (a) precipitation of ammonium nitrate in the waste, and (b) ammonium nitrate formation via the gas phase reaction of ammonia and nitrogen dioxide. The first of these can be dismissed because ammonium ions, which are necessary for ammonium nitrate precipitation, can exist only in negligibly small concentrations in strongly alkaline solutions. Gas phase reactions between ammonia, nitrogen dioxide, and water vapor in the gas phase represent the most likely means by which ammonium nitrate aerosols could be formed in Tank 241-SY-101. Predicted ammonium nitrate formation rates are largely controlled by the concentration of nitrogen dioxide. This gas has not been detected among those gases vented from the wastes using Fourier Transform Infrared Spectrometry (FTIR) or mass spectrometry. While detection limits for nitrogen dioxide have not been established experimentally, the maximum concentration of nitrogen dioxide in the gas phase in Tank 241-SY-101 was estimated at 0.1 ppm based on calculations using the HITRAN data base and on FTIR spectra of gases vented from the wastes. At 50 C and with 100 ppm ammonia also present, less than one gram of ammonium nitrate per year is estimated to be formed in the tank. To date, ammonium nitrate has not been detected on HEPA filters in the ventilation system, so any quantity that has been formed in the tank must be quite small, in good agreement with rate calculations. The potential for runaway exothermic reactions involving ammonium nitrate in Tank 241-SY-101 is minimal. Dilution by non-reacting waste components, particularly water, would prevent hazardous exothermic reactions from occurring within the waste slurry, even if ammonium nitrate were present. 41 refs

Analysis of Atmospheric Nitrate Deposition in Lake Tahoe Using Multiple Oxygen Isotopes

Science.gov (United States)

McCabe, J. R.; Michalski, G. M.; Hernandez, L. P.; Thiemens, M. H.; Taylor, K.; Kendall, C.; Wankel, S. D.

2002-12-01

Lake Tahoe in the Sierra Nevada Mountain Range is world renown for its depth and water clarity bringing 2.2 million visitors per year resulting in annual revenue of \\1.6 billion from tourism. In past decades the lake has suffered from decreased water clarity (from 32 m plate depth to less than 20), which is believed to be largely the result of algae growth initiated by increased nutrient loading. Lake nutrients have also seen a shift from a nitrogen limited to a phosphorous limited system indicating a large increase in the flux of fixed nitrogen. Several sources of fixed nitrogen of have been suggested including surface runoff, septic tank seepage from ground water and deposition from the atmosphere. Bio-available nitrogen in the form of nitrate (NO_{3}$-) is a main component of this system. Recent studies have estimated that approximately 50% of the nitrogen input into the lake is of atmospheric origin (Allison et al. 2000). However, the impact and magnitude of atmospheric deposition is still one of the least understood aspects of the relationship between air and water quality in the Basin (TRPA Threshold Assessment 2002). The utility of stable isotopes as tracers of nitrate reservoirs has been shown in several studies (Bohlke et al. 1997, Kendall and McDonnell 1998, Durka et al. 1994). Stable nitrogen (δ15N) and oxygen (δ18O) isotopes have been implemented in a dual isotope approach to characterize the various nitrate sources to an ecosystem. While δ18O distinguishes between atmospheric and soil sources of nitrate, processes such as denitrification can enrich the residual nitrate in δ18O leaving a misleading atmospheric signature. The benefit of δ15N as a tracer for NO3- sources is the ability to differentiate natural soil, fertilizer, and animal or septic waste, which contain equivalent δ18O values. The recent implementation of multiple oxygen isotopes to measure Δ17O in nitrate has proven to be a more sensitive tracer of atmospheric deposition. The

Evaluation of some feedstuffs with special emphasis on the effect of nitrate and other non-protein nitrogen fractions on ruminal microbial metabolism

International Nuclear Information System (INIS)

Nikolic, J.A.

1988-01-01

Green herbage grown under widely different conditions was examined for nitrate content. The mean value was 0.14% (range 0.01-0.32%) NO 3 -N in the dry matter (DM). It was concluded that the cut green fodder would induce high levels of blood methaemoglobin when fed to ruminants in mixed diets. Nevertheless, experiments in vitro indicated that relatively small amounts of dietary nitrate induced considerable microbial nitrate reducing activity in rumen contents. Moreover, nitrate reduction to ammonia was accompanied by alterations in microbial sulphur and energy metabolism. A technique for determining organic matter digestibility (OMD) in vitro was standardized and used to evaluate the potential nutritive value of some fruit wastes. Studies on apple pomace silage indicated that added urea did not significantly increase the silage protein content but remained as a potential source of non-protein nitrogen for rumen microorganisms. Apple pomace ensiled alone or preferably with other ingredients was acceptable to sheep and cattle, particularly as a supplement to their winter rations. (author). 27 refs, 2 figs, 5 tabs

Trend Analyses of Nitrate in Danish Groundwater

DEFF Research Database (Denmark)

Hansen, B.; Thorling, L.; Dalgaard, Tommy

2012-01-01

This presentation assesses the long-term development in the oxic groundwater nitrate concentration and nitrogen (N) loss due to intensive farming in Denmark. Firstly, up to 20-year time-series from the national groundwater monitoring network enable a statistically systematic analysis of distribut......This presentation assesses the long-term development in the oxic groundwater nitrate concentration and nitrogen (N) loss due to intensive farming in Denmark. Firstly, up to 20-year time-series from the national groundwater monitoring network enable a statistically systematic analysis...... of distribution, trends and trend reversals in the groundwater nitrate concentration. Secondly, knowledge about the N surplus in Danish agriculture since 1950 is used as an indicator of the potential loss of N. Thirdly, groundwater recharge CFC (Chlorofluorocarbon) age determination allows linking of the first...... two dataset. The development in the nitrate concentration of oxic groundwater clearly mirrors the development in the national agricultural N surplus, and a corresponding trend reversal is found in groundwater. Regulation and technical improvements in the intensive farming in Denmark have succeeded...

Nitrate removal from alkaline high nitrate effluent by in situ generation of hydrogen using zinc dust

International Nuclear Information System (INIS)

Rajagopal, S.; Chitra, S.; Paul, Biplob

2016-01-01

Alkaline radioactive low level waste generated in Nuclear Fuel Cycle contains substantial amount of nitrate and needs to be treated to meet Central Pollution Control Board discharge limits of 90 mg/L in marine coastal area. Several denitrification methods like chemical treatment, electrochemical reduction, biological denitrification, ion exchange, reverse osmosis, photochemical reduction etc are followed for removal of nitrate. In effluent treatment plants where chemical treatment is carried out, chemical denitrification can be easily adapted without any additional set up. Reducing agents like zinc and aluminum are suitable for reducing nitrate in alkaline solution. Study on denitrification with zinc dust was taken up in this work. Not much work has been done with zinc dust on reduction of nitrate to nitrogen in alkaline waste with high nitrate content. In the present work, nitrate is reduced by nascent hydrogen generated in situ, caused by reaction between zinc dust and sodium hydroxide

Use of Nitrogen-15 Isotope Method in Soils and Ground Water to Determine Potential Nitrogen Sources Affecting a Municipal Water Supply in Kansas, USA

Science.gov (United States)

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

2004-12-01

Nitrate-N concentrations have increased to greater than 10 mg/L in a municipal water supply in western Kansas from 1995 to 2002. A study was done by the Kansas Geological Survey using the nitrogen-15 natural abundance isotope method to determine potential sources for the increasing nitrate concentrations. Preliminary results of the isotope analyses on water samples suggest that animal waste and/or denitrification enrichment has affected the water supply. Soil samples from areas near the wells that were not treated with manure show a general increase of nitrogen-15 signature (+9 to +15 \\permil) to a depth of 5 m. Soils are silt loams with measurable carbonate (0.8 to 2 % by weight) in the profile, which may permit volatilization enrichment to occur in the soil profile. Wells in the area range from 11 to 20 m in alluvial deposits with depth to water at approximately 9 m). Nitrate-N values range from 8 to 26 mg/L. Nitrogen-15 values range from (+17 to +28 \\permil) with no obvious source of animal waste near the well sites. There are potential nearby long-term sources of animal waste - an abandoned sewage treatment plant and an agricultural testing farm. One well has a reducing chemistry with a nitrate value of 0.9 mg/L and a nitrogen-15 value of +17 \\permil suggesting that alluvial sediment variation also has an impact on the water quality in the study area. The other wells show values of nitrate and nitrogen-15 that are much greater than the associated soils. The use of nitrogen-15 alone permited limited evaluation of sources of nitrate to ground water particularly in areas with carbonate in the soils. Use of oxygen-18 on nitrate will permit the delineation of the processes affecting the nitrogen in the soil profile and determination of the probable sources and the processes that have affected the nitrogen in the ground water. Final results of the nitrogen-15 and oxygen-18 analyses will be presented.

Nitrogen in rock: Occurrences and biogeochemical implications

Science.gov (United States)

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.

The effects of antecedent dry days on the nitrogen removal in layered soil infiltration systems for storm run-off control.

Science.gov (United States)

Cho, Kang-Woo; Yoon, Min-Hyuk; Song, Kyung-Guen; Ahn, Kyu-Hong

2011-01-01

The effects of antecedent dry days (ADD) on nitrogen removal efficiency were investigated in soil infiltration systems, with three distinguishable layers: mulch layer (ML), coarse soil layer (CSL) and fine soil layer (FSL). Two sets of lab-scale columns with loamy CSL (C1) and sandy CSL (C2) were dosed with synthetic run-off, carrying chemical oxygen demand of 100 mg L(-1) and total nitrogen of 13 mg L(-1). The intermittent dosing cycle was stepwise adjusted for 5, 10 and 20 days. The influent ammonium and organic nitrogen were adsorbed to the entire depth in C1, while dominantly to the FSL in C2. In both columns, the effluent ammonium concentration increased while the organic nitrogen concentration decreased, as ADD increased from 5 to 20 days. The effluent of C1 always showed nitrate concentration exceeding influent, caused by nitrification, by increasing amounts as ADD increased. However, the wash-out of nitrate in C1 was not distinct in terms of mass since the effluent flow rate was only 25% of the influent. In contrast, efficient reduction (>95%) of nitrate loading was observed in C2 under ADD of 5 and 10 days, because of insignificant nitrification in the CSL and denitrification in the FSL. However, for the ADD of 20 days, a significant nitrate wash-out appeared in C2 as well, possibly because of the re-aeration by the decreasing water content in the FSL. Consequently, the total nitrogen load escaping with the effluent was always smaller in C2, supporting the effectiveness of sandy CSL over loamy FSL for nitrogen removal under various ADDs.

Enzymology and ecology of the nitrogen cycle.

Science.gov (United States)

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

2011-01-01

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

Managing tile drainage, subirrigation, and nitrogen fertilization to enhance crop yields and reduce nitrate loss.

Science.gov (United States)

Drury, C F; Tan, C S; Reynolds, W D; Welacky, T W; Oloya, T O; Gaynor, J D

2009-01-01

Improving field-crop use of fertilizer nitrogen is essential for protecting water quality and increasing crop yields. The objective of this study was to determine the effectiveness of controlled tile drainage (CD) and controlled tile drainage with subsurface irrigation (CDS) for mitigating off-field nitrate losses and enhancing crop yields. The CD and CDS systems were compared on a clay loam soil to traditional unrestricted tile drainage (UTD) under a corn (Zea Mays L.)-soybean (Glycine Max. (L.) Merr.) rotation at two nitrogen (N) fertilization rates (N1: 150 kg N ha(-1) applied to corn, no N applied to soybean; N2: 200 kg N ha(-1) applied to corn, 50 kg N ha(-1) applied to soybean). The N concentrations in tile flow events with the UTD treatment exceeded the provisional long-term aquatic life limit (LT-ALL) for freshwater (4.7 mg N L(-1)) 72% of the time at the N1 rate and 78% at the N2 rate, whereas only 24% of tile flow events at N1 and 40% at N2 exceeded the LT-ALL for the CDS treatment. Exceedances in N concentration for surface runoff and tile drainage were greater during the growing season than the non-growing season. At the N1 rate, CD and CDS reduced average annual N losses via tile drainage by 44 and 66%, respectively, relative to UTD. At the N2 rate, the average annual decreases in N loss were 31 and 68%, respectively. Crop yields from CDS were increased by an average of 2.8% relative to UTD at the N2 rate but were reduced by an average of 6.5% at the N1 rate. Hence, CD and CDS were effective for reducing average nitrate losses in tile drainage, but CDS increased average crop yields only when additional N fertilizer was applied.

Plant traits related to nitrogen uptake influence plant-microbe competition.

Science.gov (United States)

Moreau, Delphine; Pivato, Barbara; Bru, David; Busset, Hugues; Deau, Florence; Faivre, Céline; Matejicek, Annick; Strbik, Florence; Philippot, Laurent; Mougel, Christophe

2015-08-01

Plant species are important drivers of soil microbial communities. However, how plant functional traits are shaping these communities has received less attention though linking plant and microbial traits is crucial for better understanding plant-microbe interactions. Our objective was to determine how plant-microbe interactions were affected by plant traits. Specifically we analyzed how interactions between plant species and microbes involved in nitrogen cycling were affected by plant traits related to 'nitrogen nutrition in interaction with soil nitrogen availability. Eleven plant species, selected along an oligotrophic-nitrophilic gradient, were grown individually in a nitrogen-poor soil with two levels of nitrate availability. Plant traits for both carbon and nitrogen nutrition were measured and the genetic structure and abundance of rhizosphere. microbial communities, in particular the ammonia oxidizer and nitrate reducer guilds, were analyzed. The structure of the bacterial community in the rhizosphere differed significantly between plant species and these differences depended on nitrogen availability. The results suggest that the rate of nitrogen uptake per unit of root biomass and per day is a key plant trait, explaining why the effect of nitrogen availability on the structure of the bacterial community depends on the plant species. We also showed that the abundance of nitrate reducing bacteria always decreased with increasing nitrogen uptake per unit of root biomass per day, indicating that there was competition for nitrate between plants and nitrate reducing bacteria. This study demonstrates that nitrate-reducing microorganisms may be adversely affected by plants with a high nitrogen uptake rate. Our work puts forward the role of traits related to nitrogen in plant-microbe interactions, whereas carbon is commonly considered as the main driver. It also suggests that plant traits related to ecophysiological processes, such as nitrogen uptake rates, are more

Nitrogen

Science.gov (United States)

Apodaca, L.E.

2010-01-01

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

Sources and sinks of nitrogen and phosphorus to a deep, oligotrophic lake, Lake Crescent, Olympic National Park, Washington

Science.gov (United States)

Moran, P.W.; Cox, S.E.; Embrey, S.S.; Huffman, R.L.; Olsen, T.D.; Fradkin, S.C.

2012-01-01

Lake Crescent, in Olympic National Park in the northwest corner of Washington State is a deep-water lake renowned for its pristine water quality and oligotrophic nature. To examine the major sources and sinks of nutrients (as total nitrogen, total phosphorus, and dissolved nitrate), a study was conducted in the Lake Crescent watershed. The study involved measuring five major inflow streams, the Lyre River as the major outflow, recording weather and climatic data, coring lake bed sediment, and analyzing nutrient chemistry in several relevant media over 14 months. Water samples for total nitrogen, total phosphorous, and dissolved nitrate from the five inflow streams, the outlet Lyre River, and two stations in the lake were collected monthly from May 2006 through May 2007. Periodic samples of shallow water from temporary sampling wells were collected at numerous locations around the lake. Concentrations of nutrients detected in Lake Crescent and tributaries were then applied to the water budget estimates to arrive at monthly and annual loads from various environmental components within the watershed. Other sources, such as leaf litter, pollen, or automobile exhaust were estimated from annual values obtained from various literature sources. This information then was used to construct a nutrient budget for total nitrogen and total phosphorus. The nitrogen budget generally highlights vehicle traffic-diesel trucks in particular-along U.S. Highway 101 as a potential major anthropogenic source of nitrogen compounds in the lake. In contrast, contribution of nitrogen compounds from onsite septic systems appears to be relatively minor related to the other sources identified.

Dissimilatory nitrate reduction to nitrate, nitrous oxide, and ammonium by Pseudomonas putrefaciens.

Science.gov (United States)

Samuelsson, M O

1985-10-01

The influence of redox potential on dissimilatory nitrate reduction to ammonium was investigated on a marine bacterium, Pseudomonas putrefaciens. Nitrate was consumed (3.1 mmol liter-1), and ammonium was produced in cultures with glucose and without sodium thioglycolate. When sodium thioglycolate was added, nitrate was consumed at a lower rate (1.1 mmol liter-1), and no significant amounts of nitrite or ammonium were produced. No growth was detected in glucose media either with or without sodium thioglycolate. When grown on tryptic soy broth, the production of nitrous oxide paralleled growth. In the same medium, but with sodium thioglycolate, nitrous oxide was first produced during growth and then consumed. Acetylene caused the nitrous oxide to accumulate. These results and the mass balance calculations for different nitrogen components indicate that P. putrefaciens has the capacity to dissimilate nitrate to ammonium as well as to dinitrogen gas and nitrous oxide (denitrification). The dissimilatory pathway to ammonium dominates except when sodium thioglycolate is added to the medium.

The effect of alloyed nitrogen or dissolved nitrate ions on the anodic behaviour of austenitic stainless steel in hydrochloric acid

International Nuclear Information System (INIS)

Shahrabi, T.

2004-01-01

The anodic behaviour of high purity stainless steels, based on a 316L composition, has been studied at room temperature in HCl solutions from 1 to 6 M. For all acid concentrations, the presence of 0.22% nitrogen has little or no effect on the active dissolution kinetics at low over-potentials. The effect on the critical current density for passivation is also small for low HCl concentrations ( 4.5 M), no passivation occurs and again nitrogen has little effect. However, for HCl concentrations around 4 M nitrogen reversibly impedes active dissolution at a few hundred mA cm -2 . The effect does not appear to be an oxide passivation, but is more likely to be due to surface enrichment of nitrogen atoms. Implications for localized corrosion are discussed. An effect similar to that of nitrogen alloying is reproduced on a nitrogen free alloy by adding 2 M NaNO 3 to a 4M HCl solution. This effect is distinct from the passivation of salt-covered surfaces and may be preferable to the latter as an explanation of the increase in pitting potential by nitrate additions to NaCl solutions. Passivation under a salt film is retained to explain the passivation of growing pits above the inhibition potential. (authors)

Use of geomorphic, hydrologic, and nitrogen mass balance data to model ecosystem nitrate retention in tidal freshwater wetlands

Directory of Open Access Journals (Sweden)

E. D. Seldomridge

2012-07-01

Full Text Available Geomorphic characteristics have been used as scaling parameters to predict water and other fluxes in many systems. In this study, we combined geomorphic analysis with in-situ mass balance studies of nitrate retention (NR to evaluate which geomorphic scaling parameters best predicted NR in a tidal freshwater wetland ecosystem. Geomorphic characteristics were measured for 267 individual marshes that constitute the freshwater tidal wetland ecosystem of the Patuxent River, Maryland. Nitrate retention was determined from mass balance measurements conducted at the inlets of marshes of varying size (671, 5705, and 536 873 m² over a period of several years. Mass balance measurements indicate that NR is proportional to total water flux over the tidal cycle. Relationships between estimated tidal prism (calculated water volume for spring tides and various geomorphic parameters (marsh area, total channel length, and inlet width were defined using measurements from air photos and compared to field data. From these data, NR equations were determined for each geomorphic parameter, and used to estimate NR for all marshes in the ecosystem for a reference spring (high tide. The resulting ecosystem NR estimates were evaluated for (a accuracy and completeness of geomorphic data, (b relationship between the geomorphic parameters and hydrologic flux, and (c the ability to adapt the geomorphic parameter to varying tidal conditions. This analysis indicated that inlet width data were the most complete and provided the best estimate of ecosystem nitrate retention. Predictions based on marsh area were significantly lower than the inlet width-based predictions. Cumulative probability distributions of nitrate retention indicate that the largest 3–4% of the marshes retained half of the total nitrate for the ecosystem.

Nitrate removal by Fe0/Pd/Cu nano-composite in groundwater.

Science.gov (United States)

Liu, Hongyuan; Guo, Min; Zhang, Yan

2014-01-01

Nitrate pollution in groundwater shows a great threat to the safety of drinking water. Chemical reduction by zero-valent iron is being considered as a promising technique for nitrate removal from contaminated groundwater. In this paper, Fe0/Pd/Cu nano-composites were prepared by the liquid-phase reduction method, and batch experiments of nitrate reduction by the prepared Fe0/Pd/Cu nano-composites under various operating conditions were carried out. It has been found that nano-Fe0/Pd/Cu composites processed dual functions: catalytic reduction and chemical reduction. The introduction of Pd and Cu not only improved nitrate removal rate, but also reduced the generation of ammonia. Nitrate removal rate was affected by the amount of Fe0/Pd/Cu, initial nitrate concentration, solution pH, dissolved oxygen (DO), reaction temperature, the presence of anions, and organic pollutant. Moreover, nitrate reduction by Fe0/Pd/Cu composites followed the pseudo-first-order reaction kinetics. The removal rate of nitrate and total nitrogen were about 85% and 40.8%, respectively, under the reaction condition of Fe-6.0%Pd-3.0%Cu amount of 0.25 g/L, pH value of 7.1, DO of 0.42 mg/L, and initial nitrate concentration of 100 mg/L. Compared with the previous studies with Fe0 alone or Fe-Cu, nano-Fe-6%Pd-3%Cu composites showed a better selectivity to N2.

Vadose Zone Nitrate Transport Dynamics Resulting from Agricultural Groundwater Banking

Science.gov (United States)

Murphy, N. P.; McLaughlin, S.; Dahlke, H. E.

2017-12-01

In recent years, California's increased reliance on groundwater resources to meet agricultural and municipal demands has resulted in significant overdraft and water quality issues. Agricultural groundwater banking (AGB) has emerged as a promising groundwater replenishment opportunity in California; AGB is a form of managed aquifer recharge where farmland is flooded during the winter using excess surface water in order to recharge the underlying groundwater. Suitable farmland that is connected to water delivery systems is available for AGB throughout the Central Valley. However, questions remain how AGB could be implemented on fertilized agricultural fields such that nitrate leaching from the root zone is minimized. Here, we present results from field and soil column studies that investigate the transport dynamics of nitrogen in the root and deeper vadose zone during flooding events. We are specifically interested in estimating how timing and duration of flooding events affect percolation rates, leaching and nitrification/denitrification processes in three soil types within the Central Valley. Laboratory and field measurements include nitrogen (NO3-, NH4+, NO2-, N2O), redox potentials, total organic carbon, dissolved oxygen, moisture content and EC. Soil cores are collected in the field before and after recharge events up to a depth of 4m, while other sensors monitor field conditions continuously. Preliminary results from the three field sites show that significant portions of the applied floodwater (12-62 cm) infiltrated below the root zone: 96.1% (Delhi), 88.6% (Modesto) and 76.8% (Orland). Analysis of the soil cores indicate that 70% of the residual nitrate was flushed from the sandy soil, while the fine sandy loam showed only a 5% loss and in some cores even an increase in soil nitrate (in the upper 20cm). Column experiments support these trends and indicate that increases in soil nitrate in the upper root zone might be due to organic nitrogen mineralization and

The Nitrate/(Per)Chlorate Relationship on Mars

Science.gov (United States)

Stern, Jennifer C.; Sutter, Brad; Jackson, W. Andrew; Navarro-Gonzalez, Rafael; McKay, Christopher P.; Ming, Douglas W.; Archer, P. Douglas; Mahaffy, Paul R.

2017-01-01

Nitrate was recently detected in Gale Crater sediments on Mars at abundances up to approximately 600 mg/kg, confirming predictions of its presence at abundances consistent with models based on impact-generated nitrate and other sources of fixed nitrogen. Terrestrial Mars analogs, Mars meteorites, and other solar system materials help establish a context for interpreting in situ nitrate measurements on Mars, particularly in relation to other cooccuring salts. We compare the relative abundance of nitrates to oxychlorine (chlorate and/or perchlorate, hereafter (per)chlorate) salts on Mars and Earth. The nitrate/(per)chlorate ratio on Mars is greater than 1, significantly lower than on Earth (nitrate/(per)chlorate greater than 10(exp.3)), suggesting not only the absence of biological activity but also different (per)chlorate formation mechanisms on Mars than on Earth.

Genetic control of nitrate assimilation in Klebsiella oxytoca. Final technical report; FINAL

International Nuclear Information System (INIS)

Stewart, Valley J.

2001-01-01

Some microorganisms can use nitrate as the sole source of nitrogen for biosynthesis. This project focused on the bacterium Klebsiella oxytoca, an enterobacterium found in soil and water. Mutagenesis and molecular cloning identified the nasFEDCBA operon encoding enzymes for the uptake and reduction of nitrate and nitrite to ammonium, and the adjacent nasR regulatory gene. Analysis of nasF operon expression revealed that transcription is activated by the Ntr (general nitrogen regulation ) system in response to nitrogen limitation. Transcription antitermination control in response to nitrate and nitrite is mediated by the NasR protein. Additional work established that the NasR protein is an RNA-binding protein that interacts with nasF operon leader RNA to control transcription readthrough

Tracing freshwater nitrate sources in pre-alpine groundwater catchments using environmental tracers

Science.gov (United States)

Stoewer, M. M.; Knöller, K.; Stumpp, C.

2015-05-01

Groundwater is one of the main resources for drinking water. Its quality is still threatened by the widespread contaminant nitrate (NO3-). In order to manage groundwater resources in a sustainable manner, we need to find options of lowering nitrate input. Particularly, a comprehensive knowledge of nitrate sources is required in areas which are important current and future drinking water reservoirs such as pre-alpine aquifers covered with permanent grassland. The objective of the present study was to identify major sources of nitrate in groundwater with low mean nitrate concentrations (8 ± 2 mg/L). To achieve the objective, we used environmental tracer approaches in four pre-alpine groundwater catchments. The stable isotope composition and tritium content of water were used to study the hydrogeology and transit times. Furthermore, nitrate stable isotope methods were applied to trace nitrogen from its sources to groundwater. The results of the nitrate isotope analysis showed that groundwater nitrate was derived from nitrification of a variety of ammonium sources such as atmospheric deposition, mineral and organic fertilizers and soil organic matter. A direct influence of mineral fertilizer, atmospheric deposition and sewage was excluded. Since temporal variation in stable isotopes of nitrate were detected only in surface water and locally at one groundwater monitoring well, aquifers appeared to be well mixed and influenced by a continuous nitrate input mainly from soil derived nitrogen. Hydrogeological analysis supported that the investigated aquifers were less vulnerable to rapid impacts due to long average transit times, ranging from 5 to 21 years. Our study revealed the importance of combining environmental tracer approaches and a comprehensive sampling campaign (local sources of nitrate, soil water, river water, and groundwater) to identify the nitrate sources in groundwater and its vulnerability. In future, the achieved results will help develop targeted

Functional properties and differential mode of regulation of the nitrate transporter from a plant symbiotic ascomycete

Science.gov (United States)

Montanini, Barbara; Viscomi, Arturo R.; Bolchi, Angelo; Martin, Yusé; Siverio, José M.; Balestrini, Raffaella; Bonfante, Paola; Ottonello, Simone

2005-01-01

Nitrogen assimilation by plant symbiotic fungi plays a central role in the mutualistic interaction established by these organisms, as well as in nitrogen flux in a variety of soils. In the present study, we report on the functional properties, structural organization and distinctive mode of regulation of TbNrt2 (Tuber borchii NRT2 family transporter), the nitrate transporter of the mycorrhizal ascomycete T. borchii. As revealed by experiments conducted in a nitrate-uptake-defective mutant of the yeast Hansenula polymorpha, TbNrt2 is a high-affinity transporter (Km=4.7 μM nitrate) that is bispecific for nitrate and nitrite. It is expressed in free-living mycelia and in mycorrhizae, where it preferentially accumulates in the plasma membrane of root-contacting hyphae. The TbNrt2 mRNA, which is transcribed from a single-copy gene clustered with the nitrate reductase gene in the T. borchii genome, was specifically up-regulated following transfer of mycelia to nitrate- (or nitrite)-containing medium. However, at variance with the strict nitrate-dependent induction commonly observed in other organisms, TbNrt2 was also up-regulated (at both the mRNA and the protein level) following transfer to a nitrogen-free medium. This unusual mode of regulation differs from that of the adjacent nitrate reductase gene, which was expressed at basal levels under nitrogen deprivation conditions and required nitrate for induction. The functional and expression properties, described in the present study, delineate TbNrt2 as a versatile transporter that may be especially suited to cope with the fluctuating (and often low) mineral nitrogen concentrations found in most natural, especially forest, soils. PMID:16201972

Isotopic and Chemical Analysis of Nitrate Sources and Cycling in the San Joaquin River Near Stockton, California

Science.gov (United States)

Silva, S. R.; Kendall, C.; Bemis, B.; Wankel, S.; Bergamaschi, B.; Kratzer, C.; Dileanis, P.; Erickson, D.; Avery, E.; Paxton, K.

2002-12-01

Fish migration through the deep-water channel in the San Joaquin River at Stockton, California is inhibited by low oxygen concentrations during the summer months. The cause for this condition appears to be stagnation and decomposition of algae with attendant oxygen consumption. Algae growth in the San Joaquin River is promoted by nutrients entering the river mainly in the form of nitrate. Possible significant sources of nitrate include soil, fertilizer from agriculture, manure from dairy operations, and N derived from municipal sewage. A 2000 CALFED pilot study investigated the sources and cycling of nitrate at four sites along the San Joaquin River upstream of Stockton using the carbon and nitrogen isotopes of total dissolved and particulate organic matter, together with hydrological measurements and various concentration data, including chlorophyll-a. The nitrate source, its relationship to phytoplankton, and the effect of the nitrate source and cycling on the N isotopic composition of dissolved and particulate organic matter were the primary concerns of the study. The d15N values of dissolved organic nitrogen (DON) were used as a proxy for nitrate d15N because nitrate comprised about 90% of DON. Chlorophyll-a and C:N ratios indicated that the particulate organic matter (POM) consisted largely of plankton and therefore the d15N of POM was used as a proxy for the d15N of plankton. A tentative interpretation of the pilot study was that nitrate was a major nutrient for the plankton and the nitrate was of anthropogenic origin, possibly sewage or animal waste. To test these assumptions and interpretations, we are currently analyzing a set of samples collected in 2001. In addition to the previous sample types, a subset of samples will be measured directly for nitrate d15N to assess the validity of using d15N of DON as a proxy for nitrate.

Water Table Management Reduces Tile Nitrate Loss in Continuous Corn and in a Soybean-Corn Rotation

Directory of Open Access Journals (Sweden)

Craig F. Drury

2001-01-01

Full Text Available Water table management systems can be designed to alleviate soil water excesses and deficits, as well as reduce nitrate leaching losses in tile discharge. With this in mind, a standard tile drainage (DR system was compared over 8 years (1991 to 1999 to a controlled tile drainage/subirrigation (CDS system on a low-slope (0.05 to 0.1% Brookston clay loam soil (Typic Argiaquoll in southwestern Ontario, Canada. In the CDS system, tile discharge was controlled to prevent excessive drainage, and water was pumped back up the tile lines (subirrigation to replenish the crop root zone during water deficit periods. In the first phase of the study (1991 to 1994, continuous corn (Zea mays, L. was grown with annual nitrogen (N fertilizer inputs as per local soil test recommendations. In the second phase (1995 to 1999, a soybean (Glycine max L., Merr.-corn rotation was used with N fertilizer added only during the two corn years. In Phase 1 when continuous corn was grown, CDS reduced total tile discharge by 26% and total nitrate loss in tile discharge by 55%, compared to DR. In addition, the 4-year flow weighted mean (FWM nitrate concentration in tile discharge exceeded the Canadian drinking water guideline (10 mg N l–1 under DR (11.4 mg N l–1, but not under CDS (7.0 mg N l–1. In Phase 2 during the soybean-corn rotation, CDS reduced total tile discharge by 38% and total nitrate loss in tile discharge by 66%, relative to DR. The 4-year FWM nitrate concentration during Phase 2 in tile discharge was below the drinking water guideline for both DR (7.3 mg N l–1 and CDS (4.0 mg N l–1. During both phases of the experiment, the CDS treatment caused only minor increases in nitrate loss in surface runoff relative to DR. Hence CDS decreased FWM nitrate concentrations, total drainage water loss, and total nitrate loss in tile discharge relative to DR. In addition, soybean-corn rotation reduced FWM nitrate concentrations and total nitrate loss in tile discharge

Assessment of the fate of anthropogenic nitrogen in large watersheds by isotopic techniques

International Nuclear Information System (INIS)

Mayer, B.

1999-01-01

Human activity has greatly altered the nitrogen cycle in terrestrial and aquatic ecosystems and increased the nitrogen flow in many rivers. Preliminary work of the International SCOPE Nitrogen Project indicates that only 20% of the human-controlled nitrogen inputs to large watersheds are exported to the oceans in riverine flow (Howarth, 1998). Therefore, approximately 80% of the anthropogenic nitrogen inputs are either stored or denitrified in the catchments. Anthropogenic nitrogen can be retained in forests (possibly as a result of increased productivity) or in agricultural soils. It can also be stored in groundwater. These sinks are, however, often not large enough to account for the 'missing' nitrogen. It is, therefore, assumed that the majority of the human-controlled nitrogen inputs to large watersheds is denitrified in soils, riparian zones, wetlands, lakes, and rivers. Within the SCOPE Nitrogen Project, preliminary isotope analyses were performed on dissolved nitrates from several streams draining into the North Atlantic Ocean. Both δ 15 N nitrate and δ 18 O nitrate values were determined in order to identify nitrate sources. A further objective was to test, whether the isotopic composition of dissolved nitrate provides a measure for the extent to which denitrification occurs in the respective watersheds

Automated analysis for nitrate by hydrazine reduction

Energy Technology Data Exchange (ETDEWEB)

Kamphake, L J; Hannah, S A; Cohen, J M

1967-01-01

An automated procedure for the simultaneous determinations of nitrate and nitrite in water is presented. Nitrite initially present in the sample is determined by a conventional diazotization-coupling reaction. Nitrate in another portion of sample is quantitatively reduced with hydrazine sulfate to nitrite which is then determined by the same diazotization-coupling reaction. Subtracting the nitrite initially present in the sample from that after reduction yields nitrite equivalent to nitrate initially in the sample. The rate of analysis is 20 samples/hr. Applicable range of the described method is 0.05-10 mg/l nitrite or nitrate nitrogen; however, increased sensitivity can be obtained by suitable modifications.

Nitrate fertilisation does not enhance CO2 responses in two tropical seagrass species.

Science.gov (United States)

Ow, Y X; Vogel, N; Collier, C J; Holtum, J A M; Flores, F; Uthicke, S

2016-03-15

Seagrasses are often considered "winners" of ocean acidification (OA); however, seagrass productivity responses to OA could be limited by nitrogen availability, since nitrogen-derived metabolites are required for carbon assimilation. We tested nitrogen uptake and assimilation, photosynthesis, growth, and carbon allocation responses of the tropical seagrasses Halodule uninervis and Thalassia hemprichii to OA scenarios (428, 734 and 1213 μatm pCO2) under two nutrients levels (0.3 and 1.9 μM NO3(-)). Net primary production (measured as oxygen production) and growth in H. uninervis increased with pCO2 enrichment, but were not affected by nitrate enrichment. However, nitrate enrichment reduced whole plant respiration in H. uninervis. Net primary production and growth did not show significant changes with pCO2 or nitrate by the end of the experiment (24 d) in T. hemprichii. However, nitrate incorporation in T. hemprichii was higher with nitrate enrichment. There was no evidence that nitrogen demand increased with pCO2 enrichment in either species. Contrary to our initial hypothesis, nutrient increases to levels approximating present day flood plumes only had small effects on metabolism. This study highlights that the paradigm of increased productivity of seagrasses under ocean acidification may not be valid for all species under all environmental conditions.

Nitrate fertilisation does not enhance CO2 responses in two tropical seagrass species

Science.gov (United States)

Ow, Y. X.; Vogel, N.; Collier, C. J.; Holtum, J. A. M.; Flores, F.; Uthicke, S.

2016-03-01

Seagrasses are often considered “winners” of ocean acidification (OA); however, seagrass productivity responses to OA could be limited by nitrogen availability, since nitrogen-derived metabolites are required for carbon assimilation. We tested nitrogen uptake and assimilation, photosynthesis, growth, and carbon allocation responses of the tropical seagrasses Halodule uninervis and Thalassia hemprichii to OA scenarios (428, 734 and 1213 μatm pCO2) under two nutrients levels (0.3 and 1.9 μM NO3-). Net primary production (measured as oxygen production) and growth in H. uninervis increased with pCO2 enrichment, but were not affected by nitrate enrichment. However, nitrate enrichment reduced whole plant respiration in H. uninervis. Net primary production and growth did not show significant changes with pCO2 or nitrate by the end of the experiment (24 d) in T. hemprichii. However, nitrate incorporation in T. hemprichii was higher with nitrate enrichment. There was no evidence that nitrogen demand increased with pCO2 enrichment in either species. Contrary to our initial hypothesis, nutrient increases to levels approximating present day flood plumes only had small effects on metabolism. This study highlights that the paradigm of increased productivity of seagrasses under ocean acidification may not be valid for all species under all environmental conditions.

Identifying critical nitrogen application rate for maize yield and nitrate leaching in a Haplic Luvisol soil using the DNDC model.

Science.gov (United States)

Zhang, Yitao; Wang, Hongyuan; Liu, Shen; Lei, Qiuliang; Liu, Jian; He, Jianqiang; Zhai, Limei; Ren, Tianzhi; Liu, Hongbin

2015-05-01

Identification of critical nitrogen (N) application rate can provide management supports for ensuring grain yield and reducing amount of nitrate leaching to ground water. A five-year (2008-2012) field lysimeter (1 m × 2 m × 1.2 m) experiment with three N treatments (0, 180 and 240 kg Nha(-1)) was conducted to quantify maize yields and amount of nitrate leaching from a Haplic Luvisol soil in the North China Plain. The experimental data were used to calibrate and validate the process-based model of Denitrification-Decomposition (DNDC). After this, the model was used to simulate maize yield production and amount of nitrate leaching under a series of N application rates and to identify critical N application rate based on acceptable yield and amount of nitrate leaching for this cropping system. The results of model calibration and validation indicated that the model could correctly simulate maize yield and amount of nitrate leaching, with satisfactory values of RMSE-observation standard deviation ratio, model efficiency and determination coefficient. The model simulations confirmed the measurements that N application increased maize yield compared with the control, but the high N rate (240 kg Nha(-1)) did not produce more yield than the low one (120 kg Nha(-1)), and that the amount of nitrate leaching increased with increasing N application rate. The simulation results suggested that the optimal N application rate was in a range between 150 and 240 kg ha(-1), which would keep the amount of nitrate leaching below 18.4 kg NO₃(-)-Nha(-1) and meanwhile maintain acceptable maize yield above 9410 kg ha(-1). Furthermore, 180 kg Nha(-1) produced the highest yields (9837 kg ha(-1)) and comparatively lower amount of nitrate leaching (10.0 kg NO₃(-)-Nha(-1)). This study will provide a valuable reference for determining optimal N application rate (or range) in other crop systems and regions in China. Copyright © 2015 Elsevier B.V. All rights reserved.

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

Science.gov (United States)

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.

Coordinated nitrogen and carbon remobilization for nitrate assimilation in leaf, sheath and root and associated cytokinin signals during early regrowth of Lolium perenne

Czech Academy of Sciences Publication Activity Database

Roche, J.; Turnbull, M. H.; Guo, Q.; Novák, Ondřej; Späth, J.; Gieseg, S. P.; Jameson, P. E.; Love, J.

2017-01-01

Roč. 119, č. 8 (2017), s. 1353-1364 ISSN 0305-7364 R&D Projects: GA MŠk(CZ) LO1204 Institutional support: RVO:61389030 Keywords : assimilation * cytokinin * defoliation * Lolium perenne * nitrate * Nitrogen * regrowth * water-soluble carbohydrates Subject RIV: EB - Genetics ; Molecular Biology OBOR OECD: Plant sciences, botany Impact factor: 4.041, year: 2016

Total Nitrogen and Available Phosphorus Dynamics in Soils ...

African Journals Online (AJOL)

Total nitrogen and available phosphorus concentration of soils in three secondary forest fields aged 1, 5 and 10 years of age regenerating from degraded abandoned rubber plantation (Hevea brasiliensis) and a mature forest in the west African Rainforest belt in southern Nigeria were investigated in order to determine the ...

Dissolved organic nitrogen (DON) losses from nested artificially drained lowland catchments with contrasting soil types

Science.gov (United States)

Tiemeyer, Bärbel; Kahle, Petra; Lennartz, Bernd

2010-05-01

Artificial drainage is a common practice to improve moisture and aeration conditions of agricultural land. It shortens the residence time of water in the soil and may therefore contribute to the degradation of peatlands as well as to the still elevated level of diffuse pollution of surface water bodies, particularly if flow anomalies like preferential flow cause a further acceleration of water and solute fluxes. Especially in the case of nitrate, artificially drained sub-catchments are found to control the catchment-scale nitrate losses. However, it is frequently found that nitrate losses and nitrogen field balances do not match. At the same time, organic fertilizers are commonly applied and, especially in lowland catchments, organic soils have been drained for agricultural use. Thus, the question arises whether dissolved organic nitrogen (DON) forms an important component of the nitrogen losses from artificially drained catchments. However, in contrast to nitrate and even to dissolved organic carbon (DOC), this component is frequently overlooked, especially in nested catchment studies with different soil types and variable land use. Here, we will present data from a hierarchical water quantity and quality measurement programme in the federal state Mecklenburg-Vorpommern (North-Eastern Germany). The monitoring programme in the pleistocene lowland catchment comprises automatic sampling stations at a collector drain outlet (4.2 ha catchment), at a ditch draining arable land on mineral soils (179 ha), at a ditch mainly draining grassland on organic soils (85 ha) and at a brook with a small rural catchment (15.5 km²) of mixed land use and soil types. At all sampling stations, daily to weekly composite samples were taken, while the discharge and the meteorological data were recorded continuously. Water samples were analyzed for nitrate-nitrogen, ammonium-nitrogen and total nitrogen. We will compare two years: 2006/07 was a very wet year (P = 934 mm) with a high summer

Fractionation of Nitrogen and Oxygen Isotopes and Roles of Bacteria during Denitrification

Science.gov (United States)

Kang, J.; Buyanjargal, A.; Jeen, S. W.

2017-12-01

Nitrate in groundwater can cause health and environmental problems when not properly treated. The purpose of this study was to develop a treatment method for nitrate in groundwater using organic carbon-based reactive mixtures (i.e., wood chips and gravel) through column experiments and to evaluate reaction mechanisms responsible for the treatment. The column experiments were operated for a total of 19 months. The results from the geochemical analyses for the experiments suggest that cultures of denitrifying bacteria used organic carbon while utilizing nitrate as their electron acceptor via denitrification process. Proteobacteria was the most abundant phylum in all samples, accounting for 45.7% of the bacterial reads, followed by Firmicutes (22.6%) and Chlorobi (10.6%). Bacilli, Alphaproteobacteria, Betaproteobacteria, Gammaproteobacteria, and Actinobacteria_c consisted of 32, 30, 23, 11, and 2% of denitrifying bacteria class. The denitrification process caused fractionation of nitrogen and oxygen isotopes of nitrate while nitrate concentration decreased. When fitted to the Rayleigh's fractionation model, enrichment factors (ɛ) were 11.5‰ and 5.6‰ for 15N and 18O isotopes, respectively. Previous studies suggested that nitrogen isotope enrichment factors of denitrification are within the range of 4.7 to 40‰ and oxygen isotopic enrichment factors are between 8 and 18.3‰. This study shows that nitrate in groundwater can be effectively treated using passive treatment systems, such as permeable reactive barriers (PRBs), and denitrificaton is the dominant process reponsible for the removal of nitrate.

High nitrate concentrations in some Midwest United States streams in 2013 after the 2012 drought

Science.gov (United States)

Van Metre, Peter C.; Frey, Jeffrey W.; Musgrove, MaryLynn; Nakagaki, Naomi; Qi, Sharon L.; Mahler, Barbara J.; Wieczorek, Michael; Button, Daniel T.

2016-01-01

Nitrogen sources in the Mississippi River basin have been linked to degradation of stream ecology and to Gulf of Mexico hypoxia. In 2013, the USGS and the USEPA characterized water quality stressors and ecological conditions in 100 wadeable streams across the midwestern United States. Wet conditions in 2013 followed a severe drought in 2012, a weather pattern associated with elevated nitrogen concentrations and loads in streams. Nitrate concentrations during the May to August 2013 sampling period ranged from nitrate concentrations at the 100 sites were compared with May to June concentrations predicted from a regression model developed using historical nitrate data. Observed concentrations for 17 sites, centered on Iowa and southern Minnesota, were outside the 95% confidence interval of the regression-predicted mean, indicating that they were anomalously high. The sites with a nitrate anomaly had significantly higher May to June nitrate concentrations than sites without an anomaly (means, 19.8 and 3.6 mg L−1, respectively) and had higher antecedent precipitation indices, a measure of the departure from normal precipitation, in 2012 and 2013. Correlations between nitrate concentrations and watershed characteristics and nitrogen and oxygen isotopes of nitrate indicated that fertilizer and manure used in crop production, principally corn, were the dominant sources of nitrate. The anomalously high nitrate levels in parts of the Midwest in 2013 coincide with reported higher-than-normal nitrate loads in the Mississippi River.

Nitrate leaching as a confounding factor in chemical recovery from acidification in UK upland waters

International Nuclear Information System (INIS)

Curtis, C.J.; Evans, C.D.; Helliwell, R.C.; Monteith, D.T.

2005-01-01

Over the period 1988-2002, data from 18 of the 22 lakes and streams in the UK Acid Waters Monitoring Network (AWMN) show clear trends of declining excess sulphate concentrations in response to reductions in sulphur deposition, but fewer trends in increasing pH or alkalinity. There has been no significant decline in the deposition of total nitrogen over the same period, and no sites show a trend in nitrate concentration. Peak nitrate concentrations have already surpassed excess sulphate on occasion in half of the AWMN sites. Furthermore, current understanding of terrestrial N saturation processes suggests that nitrate leaching from soils may increase, even under a constant N deposition load. Best-case projections indicate that nitrate will overtake sulphate as the major excess acid anion in many sites within 10 years, while worst-case predictions with steady-state models suggest that in the longer-term, nitrate could become the dominant excess acid anion in most of the UK. - With declining excess sulphate, nitrate will become the dominant agent of continued anthropogenic acidification in many UK upland waters within a decade

Nitrogen trading tool

Science.gov (United States)

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

Atomic structure of nitrate-binding protein crucial for photosynthetic productivity

Energy Technology Data Exchange (ETDEWEB)

Koropatkin, Nicole M.; Pakrasi, Himadri B.; Smith, Thomas J.

2006-06-27

Cyanobacteria, blue-green algae, are the most abundant autotrophs in aquatic environments and form the base of all aquatic food chains by fixing carbon and nitrogen into cellular biomass. The single most important nutrient for photosynthesis and growth is nitrate, which is severely limiting in many aquatic environments particularly the open ocean (1, 2). It is therefore not surprising that NrtA, the solute-binding component of the high-affinity nitrate ABC transporter, is the single-most abundant protein in the plasma membrane of these bacteria (3). Here we describe the first structure of a nitratespecific receptor, NrtA from Synechocystis sp. PCC 6803, complexed with nitrate and determined to a resolution of 1.5Å. NrtA is significantly larger than other oxyanionbinding proteins, representing a new class of transport proteins. From sequence alignments, the only other solute-binding protein in this class is CmpA, a bicarbonatebinding protein. Therefore, these organisms created a novel solute-binding protein for two of the most important nutrients; inorganic nitrogen and carbon. The electrostatic charge distribution of NrtA appears to force the protein off of the membrane while the flexible tether facilitates the delivery of nitrate to the membrane pore. The structure not only details the determinants for nitrate selectivity in NrtA, but also the bicarbonate specificity in CmpA. Nitrate and bicarbonate transport are regulated by the cytoplasmic proteins NrtC and CmpC, respectively. Interestingly, the residues lining the ligand binding pockets suggest that they both bind nitrate. This implies that the nitrogen and carbon uptake pathways are synchronized by intracellular nitrate and nitrite.3 The nitrate ABC transporter of cyanobacteria is composed of four polypeptides (Figure 1): a high-affinity periplasmic solute-binding lipoprotein (NrtA), an integral membrane permease (NrtB), a cytoplasmic ATPase (NrtD), and a unique ATPase/solute-binding fusion protein (Nrt

Presence of nitrate NO 3 a ects animal production, photocalysis is a possible solution

Science.gov (United States)

Barba-Molina, Heli; Barba-Ortega, J.; Joya, M. R.

2016-02-01

Farmers and ranchers depend on the successful combination of livestock and crops. However, they have lost in the production by nitrate pollution. Nitrate poisoning in cattle is caused by the consumption of an excessive amount of nitrate or nitrite from grazing or water. Both humans and livestock can be affected. It would appear that well fertilised pasture seems to take up nitrogen from the soil and store it as nitrate in the leaf. Climatic conditions, favour the uptake of nitrate. Nitrate poisoning is a noninfectious disease condition that affects domestic ruminants. It is a serious problem, often resulting in the death of many animals. When nitrogen fertilizers are used to enrich soils, nitrates may be carried by rain, irrigation and other surface waters through the soil into ground water. Human and animal wastes can also contribute to nitrate contamination of ground water. A possible method to decontaminate polluted water by nitrates is with methods of fabrication of zero valent iron nanoparticles (FeNps) are found to affect their efficiency in nitrate removal from water.

Nitrate and ammonia as nitrogen sources for deep subsurface microorganisms

Directory of Open Access Journals (Sweden)

Heini eKutvonen

2015-10-01

Full Text Available We investigated the N-utilizing bacterial community in anoxic brackish groundwater of the low and intermediate level nuclear waste repository cave in Olkiluoto, Finland, at 100 m depth using 15N-based stable isotope probing (SIP and enrichment with 14/15N-ammonium or 14/15N-nitrate complemented with methane. 28 days of incubation at 12°C increased the concentration of bacterial 16S rRNA and nitrate reductase (narG gene copies in the substrate amended microcosms simultaneously with a radical drop in the overall bacterial diversity and OTU richness. Hydrogenophaga/Malikia were enriched in all substrate amended microcosms and Methylobacter in the ammonium and ammonium+methane supplemented microcosms. Sulfuricurvum was especially abundant in the nitrate+methane treatment and the unamended incubation control. Membrane-bound nitrate reductase genes (narG from Polarimonas sp. were detected in the original groundwater, while Burkholderia, Methylibium and Pseudomonas narG genes were enriched due to substrate supplements. Identified amoA genes belonged to Nitrosomonas sp. 15N-SIP revealed that Burkholderiales and Rhizobiales clades belonging to the minority groups in the original groundwater used 15N from ammonium and nitrate as N source indicating an important ecological function of these bacteria, despite their low number, in the groundwater N cycle in Olkiluoto bedrock system.

Reexamining the risks of drinking-water nitrates on public health.

Science.gov (United States)

Richard, Alyce M; Diaz, James H; Kaye, Alan David

2014-01-01

Nitrates in drinking water are generally considered the sole source of nitrite poisoning with methemoglobinemia in infantile methomoglobinemia (IM). However, IM, which occurs during the first 4 months of life, is actually a constellation of cyanosis and hypoxia associated with methemoglobinemia that can result from several other causes. This review reexamines the role of nitrate levels in drinking water as a cause of IM and identifies other sources of nitrates that can affect public health and cause chronic diseases. Causes of IM include nitrites in foods, environmental chemical exposures, commonly prescribed pharmaceuticals, and the endogenous generation of oxides of nitrogen. Infants with congenital enzyme deficiencies in glucose-6-phosphate dehydrogenase and methemoglobin reductase are at greater risk of nitrite-induced methemoglobinemia from nitrates in water and food and from exposures to hemoglobin oxidizers. Early epidemiological studies demonstrated significant associations between high groundwater nitrate levels and elevated methemoglobin levels in infants fed drinking water-diluted formulas. However, more recent epidemiological investigations suggest other sources of nitrogenous substance exposures in infants, including protein-based formulas and foods and the production of nitrate precursors (nitric acid) by bacterial action in the infant gut in response to inflammation and infection.

Nitrate and nitrite in biology, nutrition and therapeutics

Science.gov (United States)

Lundberg, Jon O.; Gladwin, Mark T.; Ahluwalia, Amrita; Benjamin, Nigel; Bryan, Nathan S.; Butler, Anthony; Cabrales, Pedro; Fago, Angela; Feelisch, Martin; Ford, Peter C.; Freeman, Bruce A.; Frenneau, Michael; Friedman, Joel; Kelm, Malte; Kevil, Christopher G.; Kim-Shapiro, Daniel B.; Kozlov, Andrey V.; Lancaster, Jack R.; Lefer, David J.; McColl, Kenneth; McCurry, Kenneth; Patel, Rakesh; Petersson, Joel; Rassaf, Tienush; Reutov, Valentin P.; Richter-Addo, George B.; Schechter, Alan; Shiva, Sruti; Tsuchiya, Koichiro; van Faassen, Ernst E.; Webb, Andrew J.; Zuckerbraun, Brian S.; Zweier, Jay L.; Weitzberg, Eddie

2014-01-01

Inorganic nitrate and nitrite from endogenous or dietary sources are metabolized in vivo to nitric oxide (NO) and other bioactive nitrogen oxides. The nitrate-nitrite-NO pathway is emerging as an important mediator of blood flow regulation, cell signaling, energetics and tissue responses to hypoxia. The latest advances in our understanding of the biochemistry, physiology and therapeutics of nitrate, nitrite and NO were discussed during a recent two-day meeting at the Nobel Forum, Karolinska Institutet in Stockholm. PMID:19915529

Assessing bottled water nitrate concentrations to evaluate total drinking water nitrate exposure and risk of birth defects.

Science.gov (United States)

Weyer, Peter J; Brender, Jean D; Romitti, Paul A; Kantamneni, Jiji R; Crawford, David; Sharkey, Joseph R; Shinde, Mayura; Horel, Scott A; Vuong, Ann M; Langlois, Peter H

2014-12-01

Previous epidemiologic studies of maternal exposure to drinking water nitrate did not account for bottled water consumption. The objective of this National Birth Defects Prevention Study (NBDPS) (USA) analysis was to assess the impact of bottled water use on the relation between maternal exposure to drinking water nitrate and selected birth defects in infants born during 1997-2005. Prenatal residences of 1,410 mothers reporting exclusive bottled water use were geocoded and mapped; 326 bottled water samples were collected and analyzed using Environmental Protection Agency Method 300.0. Median bottled water nitrate concentrations were assigned by community; mothers' overall intake of nitrate in mg/day from drinking water was calculated. Odds ratios for neural tube defects, limb deficiencies, oral cleft defects, and heart defects were estimated using mixed-effects models for logistic regression. Odds ratios (95% CIs) for the highest exposure group in offspring of mothers reporting exclusive use of bottled water were: neural tube defects [1.42 (0.51, 3.99)], limb deficiencies [1.86 (0.51, 6.80)], oral clefts [1.43 (0.61, 3.31)], and heart defects [2.13, (0.87, 5.17)]. Bottled water nitrate had no appreciable impact on risk for birth defects in the NBDPS.

What is the prognosis of nitrogen losses from UK soils?

Science.gov (United States)

Burt, T. P.; Worrall, F.; Whelan, M.; Howden, N. J.

2009-12-01

The UK’s high population density, intensive agriculture and relative short, unimpeded rivers mean that the UK is a known “hotspot” of fluvial nitrogen flux. Furthermore, it is known that the fluvial flux of nitrogen from the UK is increasing. This study estimates the release of nitrate from the UK terrestrial biosphere to understand this rising fluvial flux and i to assess the in-stream losses of nitrate, thusgiving an assessment of the fluvial component of the total nitrogen budget of UK. The approach taken by the study is to use an export coefficient model coupled with a description of mineralisation and immobilisation of nitrogen within soil reserves. The study applies the modelling approach to the whole of the UK from 1925 to 2007 using long term records of: land use (including - agricultural, forestry and urban uses); livestock; human population and atmospheric deposition. The study shows that: i) The flux of nitrate from the UK soils varied from 420 to 1463 Ktonnes N/yr with two peaks in the period since 1925, one in 1944 and one in 1967, the first is caused by mineralisation of soil organic matter following large-scale land use change in the Second World War, and the second is a multifactorial response to land use change and intensification. ii) The current trend in the release from soils is downward whilst the current fluvial flux at the tidal limit is upwards. With the current trends fluvial flux at the tidal limit will be greater than release from the soils of the UK, i.e. there will be net gain across the fluvial network. This apparent gain can be explained by the breakthrough of high nitrate groundwater into surface waters.

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

Energy Technology Data Exchange (ETDEWEB)

Kaste, Oe; Bechmann, M; Toerset, K

1994-07-01

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

Observations of the diurnal and seasonal trends in nitrogen oxides in the western Sierra Nevada

Directory of Open Access Journals (Sweden)

J. G. Murphy

2006-01-01

Full Text Available Observations of speciated nitrogen oxides, namely NO2, total peroxy nitrates (ΣPNs, total alkyl nitrates (ΣANs, and HNO3 by thermal dissociation laser induced fluorescence (TD-LIF, and supporting chemical and meteorological measurements at Big Hill (1860 m, a high elevation site in California's Sierra Nevada Mountains, are described. From May through October, terrain-driven winds in the region routinely bring air from Sacramento, 100 km southwest of the site, upslope over oak and pine forests to Big Hill during the day, while at night, the site often samples clean, dry air characteristic of the free troposphere. Winter differs mainly in that the meteorology does not favour the buildup of Sacramento's pollution over the Sierra Nevada range, and the urban-influenced air that is seen has been less affected by biogenic VOC emissions, resulting in longer lifetime for NO2 and a predominance of the inorganic forms of nitrogen oxides. Summertime observations at Big Hill can be compared with those from Granite Bay, a Sacramento suburb, and from the University of California's Blodgett Forest Research Station to examine the evolution of nitrogen oxides and ozone within the urban plume. Nitrogen oxide radicals (NO and NO2, which dominate total nitrogen oxides (NOy at Granite Bay, are rapidly converted into HNO3, ΣPNs, and ΣANs, such that these compounds contribute 29, 30, and 21% respectively to the NOy budget in the plume at Big Hill. Nevertheless, the decreasing concentrations of NO2 as the plume is advected to Big Hill lead to decreases in the production rate of HNO3 and ozone. The data also demonstrate the role that temperature plays in sequestering NO2 into peroxy nitrates, effectively decreasing the rate of ozone production. The important contribution of ΣANs to NOy in the region suggests that they should be considered with regards to export of NOy from the boundary layer. Nocturnal observations of airmasses characteristic of the

Sulfate, nitrate and blood pressure - An EPIC interaction between sulfur and nitrogen.

Science.gov (United States)

Kuhnle, Gunter G; Luben, Robert; Khaw, Kay-Tee; Feelisch, Martin

2017-08-01

Nitrate (NO 3 - )-rich foods such as green leafy vegetables are not only part of a healthy diet, but increasingly marketed for primary prevention of cardiovascular disease (CVD) and used as ergogenic aids by competitive athletes. While there is abundant evidence for mild hypotensive effects of nitrate on acute application there is limited data on chronic intake in humans, and results from animal studies suggest no long-term benefit. This is important as nitrate can also promote the formation of nitrosamines. It is therefore classified as 'probably carcinogenic to humans', although a beneficial effect on CVD risk might compensate for an increased cancer risk. Dietary nitrate requires reduction to nitrite (NO 2 - ) by oral commensal bacteria to contribute to the formation of nitric oxide (NO). The extensive crosstalk between NO and hydrogen sulfide (H 2 S) related metabolites may further affect nitrate's bioactivity. Using nitrate and nitrite concentrations of drinking water - the only dietary source continuously monitored for which detailed data exist - in conjunction with data of >14,000 participants of the EPIC-Norfolk study, we found no inverse associations with blood pressure or CVD risk. Instead, we found a strong interaction with sulfate (SO 4 2- ). At low sulfate concentrations, nitrate was inversely associated with BP (-4mmHg in top quintile) whereas this was reversed at higher concentrations (+3mmHg in top quintile). Our findings have a potentially significant impact for pharmacology, physiology and public health, redirecting our attention from the oral microbiome and mouthwash use to interaction with sulfur-containing dietary constituents. These results also indicate that nitrate bioactivation is more complex than hitherto assumed. The modulation of nitrate bioactivity by sulfate may render dietary lifestyle interventions aimed at increasing nitrate intake ineffective and even reverse potential antihypertensive effects, warranting further investigation

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

Science.gov (United States)

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

2014-01-01

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

15N studies on the in-vivo assay of nitrate reductase in leaves

International Nuclear Information System (INIS)

Yoneyama, Tadakatsu

1981-01-01

The reduction of nitrate and nitrite in the leaf disks of seven di- and two mono-cotyledonous species under the in-vivo assay conditions of nitrate reductase was studied using N-15 labeled substrates. The significant reduction of both nitrate and nitrite into ammonia and amino acids was detected in the atmosphere of air. In the atmosphere of N 2 gas, anaerobic incubation enhanced the accumulation of nitrite, but the subsequent reduction to the basic nitrogen compounds was from 40 to 180 % of the aerobic rate. The present examination indicated that the in-vivo assay of nitrate reductase under aerobic condition may give greatly underestimated results due to nitrite reduction, and that the exclusion of oxygen from the in-vivo assay mixture is desirable. The addition of n- propanol may be desirable for the assay under aerobic condition. Significant difference was not observed in the reduction of nitrate supplied as sodium and potassium salts on the nitrite formation and on the incorporation of nitrate-N into basic fractions. The N-15 experiment on the dark assimilation of nitrate, nitrite and ammonia into amino acids in wheat leaves showed that these three nitrogen sources were assimilated through the same route, and that the glutamine synthetase/glutamate synthetase pathway was the main route. By anaerobic treatment, the incorporation of nitrogen into alanine and serine was relatively high. (Kako, I.)

Loss of nitrogen (study with 15N) as gaseous oxides under submerged conditions of paddy

International Nuclear Information System (INIS)

Mandal, S.R.; Datta, N.P.

1987-01-01

The experiment in a specially designed, air-tight pot with rice and different water soluble grades of nitrophosphate, ammonium nitrate (plus super phosphate) tagged with six atom per cent excess 15 N clearly revealed that the loss of nitrogen as oxides during the growth period of rice under submerged condition was very small (1.48 to 2.57 mg/pot). The 15 N content in the lost oxides was also very small and a small traction of total nitrogen applied represented the loss in this channel (0.0062 to 0.0163 per cent). The loss was influenced by NH 4 :NO 3 ratio in the fertilizer and increased with the increasing quantity of nitrate present in the fertilizers. (author)

Identification of groundwater nitrate sources in pre-alpine catchments: a multi-tracer approach

Science.gov (United States)

Stoewer, Myriam; Stumpp, Christine

2014-05-01

Porous aquifers in pre-alpine areas are often used as drinking water resources due to their good water quality status and water yield. Maintaining these resources requires knowledge about possible sources of pollutants and a sustainable management practice in groundwater catchment areas. Of particular interest in agricultural areas, like in pre-alpine regions, is limiting nitrate input as main groundwater pollutant. Therefore, the objective of the presented study is i) to identify main nitrate sources in a pre-alpine groundwater catchment with current low nitrate concentration using stable isotopes of nitrate (d18O and d15N) and ii) to investigate seasonal dynamics of nitrogen compounds. The groundwater catchment areas of four porous aquifers are located in Southern Germany. Most of the land use is organic grassland farming as well as forestry and residential area. Thus, potential sources of nitrate mainly are mineral fertilizer, manure/slurry, leaking sewage system and atmospheric deposition of nitrogen compounds. Monthly freshwater samples (precipitation, river water and groundwater) are analysed for stable isotope of water (d2H, d18O), the concentration of major anions and cations, electrical conductivity, water temperature, pH and oxygen. In addition, isotopic analysis of d18O-NO3- and d15N-NO3- for selected samples is carried out using the denitrifier method. In general, all groundwater samples were oxic (10.0±2.6mg/L) and nitrate concentrations were low (0.2 - 14.6mg/L). The observed nitrate isotope values in the observation area compared to values from local precipitation, sewage, manure and mineral fertilizer as well as to data from literature shows that the nitrate in freshwater samples is of microbial origin. Nitrate derived from ammonium in fertilizers and precipitation as well as from soil nitrogen. It is suggested that a major potential threat to the groundwater quality is ammonia and ammonium at a constant level mainly from agriculture activities as

Total Protein Content Determination of Microalgal Biomass by Elemental Nitrogen Analysis and a Dedicated Nitrogen-to-Protein Conversion Factor

Energy Technology Data Exchange (ETDEWEB)

Laurens, Lieve M [National Renewable Energy Laboratory (NREL), Golden, CO (United States); Olstad-Thompson, Jessica L [National Renewable Energy Laboratory (NREL), Golden, CO (United States); Templeton, David W [National Renewable Energy Laboratory (NREL), Golden, CO (United States)

2018-04-02

Accurately determining protein content is important in the valorization of algal biomass in food, feed, and fuel markets, where these values are used for component balance calculations. Conversion of elemental nitrogen to protein is a well-accepted and widely practiced method, but depends on developing an applicable nitrogen-to-protein conversion factor. The methodology reported here covers the quantitative assessment of the total nitrogen content of algal biomass and a description of the methodology that underpins the accurate de novo calculation of a dedicated nitrogen-to-protein conversion factor.

The impact of nitrogen deposition on acid grasslands in the Atlantic region of Europe

Energy Technology Data Exchange (ETDEWEB)

Stevens, Carly J., E-mail: c.j.stevens@open.ac.uk [Department of Life Sciences, The Open University, Walton Hall, Milton Keynes MK7 6AA (United Kingdom); Lancaster Environment Centre, Lancaster University, Lancaster LA1 4YQ (United Kingdom); Dupre, Cecilia [Institute of Ecology, FB 2, University of Bremen, Leobener Str., DE-28359 Bremen (Germany); Dorland, Edu [Ecology and Biodiversity Group, Department of Biology, Institute of Environmental Biology, Utrecht University, PO Box 80.058, 3508 TB Utrecht (Netherlands); Gaudnik, Cassandre [University of Bordeaux 1, UMR INRA 1202 Biodiversity, Genes and Communities, Equipe Ecologie des Communautes, Batiment B8 - Avenue des Facultes, F-33405 Talence (France); Gowing, David J.G. [Department of Life Sciences, The Open University, Walton Hall, Milton Keynes MK7 6AA (United Kingdom); Bleeker, Albert [Department of Air Quality and Climate Change, Energy Research Centre of the Netherlands, PO Box 1, 1755 ZG Petten (Netherlands); Diekmann, Martin [Institute of Ecology, FB 2, University of Bremen, Leobener Str., DE-28359 Bremen (Germany); Alard, Didier [University of Bordeaux 1, UMR INRA 1202 Biodiversity, Genes and Communities, Equipe Ecologie des Communautes, Batiment B8 - Avenue des Facultes, F-33405 Talence (France); Bobbink, Roland [B-WARE Research Centre, Radboud University, PO Box 9010, 6525 ED Nijmegen (Netherlands); Fowler, David [NERC Centre for Ecology and Hydrology, Bush Estate, Penicuik, Midlothian EH26 0QB (United Kingdom); Corcket, Emmanuel [University of Bordeaux 1, UMR INRA 1202 Biodiversity, Genes and Communities, Equipe Ecologie des Communautes, Batiment B8 - Avenue des Facultes, F-33405 Talence (France); Mountford, J. Owen [NERC Centre for Ecology and Hydrology, MacLean Building, Benson Lane, Crowmarsh Gifford, Wallingford, Oxfordshire OX10 8BB (United Kingdom); Vandvik, Vigdis [Department of Biology, University of Bergen, Box 7800, N-5020 Bergen (Norway)

2011-10-15

A survey of 153 acid grasslands from the Atlantic biogeographic region of Europe indicates that chronic nitrogen deposition is changing plant species composition and soil and plant-tissue chemistry. Across the deposition gradient (2-44 kg N ha{sup -1} yr{sup -1}) grass richness as a proportion of total species richness increased whereas forb richness decreased. Soil C:N ratio increased, but soil extractable nitrate and ammonium concentrations did not show any relationship with nitrogen deposition. The above-ground tissue nitrogen contents of three plant species were examined: Agrostis capillaris (grass), Galium saxatile (forb) and Rhytidiadelphus squarrosus (bryophyte). The tissue nitrogen content of neither vascular plant species showed any relationship with nitrogen deposition, but there was a weak positive relationship between R. squarrosus nitrogen content and nitrogen deposition. None of the species showed strong relationships between above-ground tissue N:P or C:N and nitrogen deposition, indicating that they are not good indicators of deposition rate. - Highlights: > N deposition is negatively correlated with forb richness as a proportion of species richness. > Soil C:N ratio increased with increasing N deposition. > Soil extractable nitrate and ammonium were not related to nitrogen deposition. > Plant-tissue N content was not a good indicator of N deposition. - Atmospheric nitrogen deposition affects soils, plant-tissue chemistry and plant species composition in acid grasslands in the Atlantic biogeographic region of Europe.

The impact of nitrogen deposition on acid grasslands in the Atlantic region of Europe

International Nuclear Information System (INIS)

Stevens, Carly J.; Dupre, Cecilia; Dorland, Edu; Gaudnik, Cassandre; Gowing, David J.G.; Bleeker, Albert; Diekmann, Martin; Alard, Didier; Bobbink, Roland; Fowler, David; Corcket, Emmanuel; Mountford, J. Owen; Vandvik, Vigdis

2011-01-01

A survey of 153 acid grasslands from the Atlantic biogeographic region of Europe indicates that chronic nitrogen deposition is changing plant species composition and soil and plant-tissue chemistry. Across the deposition gradient (2-44 kg N ha -1 yr -1 ) grass richness as a proportion of total species richness increased whereas forb richness decreased. Soil C:N ratio increased, but soil extractable nitrate and ammonium concentrations did not show any relationship with nitrogen deposition. The above-ground tissue nitrogen contents of three plant species were examined: Agrostis capillaris (grass), Galium saxatile (forb) and Rhytidiadelphus squarrosus (bryophyte). The tissue nitrogen content of neither vascular plant species showed any relationship with nitrogen deposition, but there was a weak positive relationship between R. squarrosus nitrogen content and nitrogen deposition. None of the species showed strong relationships between above-ground tissue N:P or C:N and nitrogen deposition, indicating that they are not good indicators of deposition rate. - Highlights: → N deposition is negatively correlated with forb richness as a proportion of species richness. → Soil C:N ratio increased with increasing N deposition. → Soil extractable nitrate and ammonium were not related to nitrogen deposition. → Plant-tissue N content was not a good indicator of N deposition. - Atmospheric nitrogen deposition affects soils, plant-tissue chemistry and plant species composition in acid grasslands in the Atlantic biogeographic region of Europe.

Effect of nitrification inhibitors on the content of available nitrogen forms in the soil under maize (Zea mays, L. growing

Directory of Open Access Journals (Sweden)

Zuzana PANAKOVA

2016-12-01

Full Text Available The objective of this research was to investigate the effect of nitrification inhibitors (dicyandiamide and 1,2,4 triazole on the content of nitrate and ammonium nitrogen in the soil and the effectiveness of nitrogen-sulphur nutrition of maize. The research was conducted in field small-plot experiment with maize on Haplic Luvisol with dominance of clay fraction in experimental years 2012 to 2015. The dose of nitrogen in all experimental treatments was 160 kg*ha-1 and was applied at one shot or split in three partial doses. Soil samples from all examined treatments were taken from three soil depths (0.0-0.3 m, 0.3-0.6 m and 0.6-0.9 m, respectively by probe rod in 4-5 week intervals. Achieved results indicate that on the average of four years and three depths of the soil profile, application of nitrification inhibitors contained in fertilizer ENSIN considerably reduced portion of nitrate nitrogen from the content of mineral nitrogen in the soil by 7-32 relative %. The application of fertilizer ENSIN considerably increased content of ammonium nitrogen in the soil by 10-59 relative %. A favourable effect on increase of ammonium nitrogen content and reduction of nitrate nitrogen content was found out in spite of the fact that in this treatment the total dose of fertilizer was applied at one shot.

Nitrogen and Martian Habitability: Insights from Five Years of Curiosity Measurements

Science.gov (United States)

Stern, J. C.; Sutter, B.; Navarro-Gonzalez, R.; McKay, C.; Ming, D. W.; Mahaffy, P. R.; Archer, D., Jr.; Franz, H. B.; Freissinet, C.; Jackson, W. A.; Conrad, P. G.; Glavin, D. P.; Trainer, M. G.; Malespin, C.; McAdam, A.; Eigenbrode, J. L.; Teinturier, S.; Manning, C.

2017-12-01

The detection of "fixed" N on Mars in the form of nitrate by the Sample Analysis at Mars (SAM) instrument suite on the Mars Science Laboratory (MSL) Curiosity Rover [1] has major implications for martian habitability. "Follow the nitrogen" has been proposed as a strategy in the search for both extant and extinct life on Mars [e.g., 2]. Nitrogen is so crucial to life on Earth that life developed metabolic pathways to break the triple bond of N2 and "fix" atmospheric nitrogen to more biologically available molecules for use in proteins and informational polymers. Sequestration of nitrate in regolith has long been predicted to contribute to the removal of N from the martian atmosphere [e.g., 3], and our detections confirm that nitrogen fixation was occurring on ancient Mars. Detections of fixed nitrogen, particularly within the context of the habitable environment in Yellowknife Bay characterized by the MSL payload, are an important tool to assess whether life ever could have existed on ancient Mars. We present 5 years of analyses and interpretation of nitrate in solid martian drilled and scooped samples by SAM on MSL. Nitrate abundance reported by SAM in situ measurements ranges from non-detection to 681 ± 304 mg/kg [1,4] in the samples examined to date. The measured abundances are consistent with nitrogen fixation via impact generated thermal shock on ancient Mars and/or dry deposition from photochemistry of thermospheric NO. We review the integration of SAM data with terrestrial Mars analog work in order to better understand the timing of nitrogen fixation and mobility of nitrogen on Mars, and thus its availability to putative biology. In particular, the relationship between nitrate and other soluble salts, such as perchlorate, may help reveal the timing of nitrogen fixation and post-depositional behavior of nitrate on Mars [4]. Finally, we present a comparison of isotopic composition (δ15N) of nitrate with δ15N of atmospheric nitrogen (δ15N ≈ 574‰, [5

Nitrogen deposition in precipitation to a monsoon-affected eutrophic embayment: Fluxes, sources, and processes

Science.gov (United States)

Wu, Yunchao; Zhang, Jingping; Liu, Songlin; Jiang, Zhijian; Arbi, Iman; Huang, Xiaoping; Macreadie, Peter Ian

2018-06-01

Daya Bay in the South China Sea (SCS) has experienced rapid nitrogen pollution and intensified eutrophication in the past decade due to economic development. Here, we estimated the deposition fluxes of nitrogenous species, clarified the contribution of nitrogen from precipitation and measured ions and isotopic composition (δ15N and δ18O) of nitrate in precipitation in one year period to trace its sources and formation processes among different seasons. We found that the deposition fluxes of total dissolved nitrogen (TDN), NO3-, NH4+, NO2-, and dissolved organic nitrogen (DON) to Daya Bay were 132.5, 64.4 17.5, 1.0, 49.6 mmol m-2•yr-1, respectively. DON was a significant contributor to nitrogen deposition (37% of TDN), and NO3- accounted for 78% of the DIN in precipitation. The nitrogen deposition fluxes were higher in spring and summer, and lower in winter. Nitrogen from precipitation contributed nearly 38% of the total input of nitrogen (point sources input and dry and wet deposition) in Daya Bay. The δ15N-NO3- abundance, ion compositions, and air mass backward trajectories implicated that coal combustion, vehicle exhausts, and dust from mainland China delivered by northeast monsoon were the main sources in winter, while fossil fuel combustion (coal combustion and vehicle exhausts) and dust from PRD and southeast Asia transported by southwest monsoon were the main sources in spring; marine sources, vehicle exhausts and lightning could be the potential sources in summer. δ18O results showed that OH pathway was dominant in the chemical formation process of nitrate in summer, while N2O5+ DMS/HC pathways in winter and spring.

Oxidized Nitrogen Balance over 15 Months at Rural and Urban New York State Locations

Science.gov (United States)

Schwab, J. J.; Ninneman, M.; Marto, J.; Edgerton, E. S.; Blanchard, C. L.; Shaw, S. L.

2017-12-01

Continuous measurements of oxidized nitrogen species (NO, NO2, and HNO3), families of species (NOy, alkyl nitrates [or ANs], and peroxyacetyl nitrates [or PANs]), and particle nitrate (pNO3) were carried out for a fifteen-month period from August 2016 through October 2017 at two locations in New York State. The two sites were a rural research station at Pinnacle State Park in Addison, NY and an urban research station at Queens College in New York City. Four different chemiluminescence analyzers with various converters and denuders were employed to make these measurements. Instrumentation used for the study will be described, as well as some of the challenges created by combining data from these independent analyzers to address the oxidized nitrogen budget at the two sites. The Pinnacle State Park site often experiences quite clean air with low ppb levels of total NOy and a greater fraction of oxidized nitrogen products (NOz species). This contrasts with the urban Queens College location, which experiences stronger NOx sources. Seasonal differences in the NOx/NOy and NOz/NOy ratios, and the makeup of the NOz species, are also significant and will be explored in the presentation.

Isotopic Assessment of Nitrogen Cycling in River Basins: Potential and Limitations for Nutrient Management Purposes

Energy Technology Data Exchange (ETDEWEB)

Mayer, B. [Department of Geoscience, University of Calgary, Calgary, Alberta (Canada); Sebilo, M. [PMC University Paris 06, UMR BIOEMCO, Paris (France); Wassenaar, L. I. [Environment Canada, Saskatoon (Canada)

2013-05-15

It has been proposed that the stable isotopic composition of riverine nitrate may help reveal the predominant sources of N loading of riverine systems, including inorganic fertilizers and manure derived nitrates from agricultural systems and nitrates from urban wastewater effluents. A literature review reveals that rivers in pristine and forested headwaters are generally characterized by low nitrate concentrations and {delta}{sup 15}N{sub nitrate} values <5 per mille, whereas rivers draining well developed watersheds characterized by major urban centres and/or intensive agriculture have higher nitrate concentrations and {delta}{sup 15}N{sub nitrate} values of between +5 and +15% per mille. Relating elevated {delta}{sup 15}N{sub nitrate} values to specific nitrogen sources or to estimate nutrient loading rates for management purposes, however, is challenging for a variety of reasons: (1) the nitrogen isotopic composition of agricultural derived nitrate can be variable and may overlap with the {delta}{sup 15}N value of wastewater nitrate; (2) soil zone and riparian denitrification may cause changes in the concentration and isotopic composition of riverine nitrate; and (3) in-stream nutrient uptake processes may affect the isotopic composition of dissolved nitrogen compounds. To maximize the information gained from isotopic studies of riverine nitrogen compounds we recommend that: (1) numerous sampling sites are established along a river and sampled frequently in order to capture spatial and seasonal changes; (2) the isotopic composition of nitrate (including {sup 18}O/{sup 16}O) and dissolved ammonium be determined if possible; (3) riverine nitrogen loading be determined and interpreted in context along with isotope data, and; (4) major and relevant nitrogen inputs to the watershed be identified and their isotopic values measured. This approach will help to minimize ambiguities in the interpretation of obtained isotope data and maximize the information required for

Verifiable metamodels for nitrate losses to drains and groundwater in the Corn Belt, USA

Science.gov (United States)

Nolan, Bernard T.; Malone, Robert W.; Gronberg, Jo Ann M.; Thorp, K.R.; Ma, Liwang

2012-01-01

Nitrate leaching in the unsaturated zone poses a risk to groundwater, whereas nitrate in tile drainage is conveyed directly to streams. We developed metamodels (MMs) consisting of artificial neural networks to simplify and upscale mechanistic fate and transport models for prediction of nitrate losses by drains and leaching in the Corn Belt, USA. The two final MMs predicted nitrate concentration and flux, respectively, in the shallow subsurface. Because each MM considered both tile drainage and leaching, they represent an integrated approach to vulnerability assessment. The MMs used readily available data comprising farm fertilizer nitrogen (N), weather data, and soil properties as inputs; therefore, they were well suited for regional extrapolation. The MMs effectively related the outputs of the underlying mechanistic model (Root Zone Water Quality Model) to the inputs (R2 = 0.986 for the nitrate concentration MM). Predicted nitrate concentration was compared with measured nitrate in 38 samples of recently recharged groundwater, yielding a Pearson’s r of 0.466 (p = 0.003). Predicted nitrate generally was higher than that measured in groundwater, possibly as a result of the time-lag for modern recharge to reach well screens, denitrification in groundwater, or interception of recharge by tile drains. In a qualitative comparison, predicted nitrate concentration also compared favorably with results from a previous regression model that predicted total N in streams.

Denitrification controls in urban riparian soils: implications for reducing urban nonpoint source nitrogen pollution.

Science.gov (United States)

Li, Yangjie; Chen, Zhenlou; Lou, Huanjie; Wang, Dongqi; Deng, Huanguang; Wang, Chu

2014-09-01

The purpose of this research was to thoroughly analyze the influences of environmental factors on denitrification processes in urban riparian soils. Besides, the study was also carried out to identify whether the denitrification processes in urban riparian soils could control nonpoint source nitrogen pollution in urban areas. The denitrification rates (DR) over 1 year were measured using an acetylene inhibition technique during the incubation of intact soil cores from six urban riparian sites, which could be divided into three types according to their vegetation. The soil samples were analyzed to determine the soil organic carbon (SOC), soil total nitrogen (STN), C/N ratio, extractable NO3 (-)-N and NH4 (+)-N, pH value, soil water content (SWC), and the soil nitrification potential to evaluate which of these factors determined the final outcome of denitrification. A nitrate amendment experiment further indicated that the riparian DR was responsive to added nitrate. Although the DRs were very low (0.099 ~ 33.23 ng N2O-N g(-1) h(-1)) due to the small amount of nitrogen moving into the urban riparian zone, the spatial and temporal patterns of denitrification differed significantly. The extractable NO3 (-)-N proved to be the dominant factor influencing the spatial distribution of denitrification, whereas the soil temperature was a determinant of the seasonal DR variation. The six riparian sites could also be divided into two types (a nitrate-abundant and a nitrate-stressed riparian system) according to the soil NO3 (-)-N concentration. The DR in nitrate-abundant riparian systems was significantly higher than that in the nitrate-stressed riparian systems. The DR in riparian zones that were covered with bushes and had adjacent cropland was higher than in grass-covered riparian sites. Furthermore, the riparian DR decreased with soil depth, which was mainly attributed to the concentrated nitrate in surface soils. The DR was not associated with the SOC, STN, C/N ratio, and

δ(15)N and δ(18)O Reveal the Sources of Nitrate-Nitrogen in Urban Residential Stormwater Runoff.

Science.gov (United States)

Yang, Yun-Ya; Toor, Gurpal S

2016-03-15

Nitrogen (N) sources are widely distributed in the complex urban environment. High-resolution data elucidating N sources in the residential catchments are not available. We used stable isotopes of N and oxygen (O) of nitrate (δ(18)O-NO3(-) and δ(15)N-NO3(-)) along with δ(18)O and hydrogen (δD) of water (H2O) to understand the sources and transformations of N in residential stormwater runoff. Stormwater runoff samples were collected over 25 stormwater events at 5 min intervals using an autosampler installed at the residential catchment outlet pipe that drained 31 low-density homes with a total drainage area of 0.11 km(2). Bayesian mixing model results indicated that atmospheric deposition (range 43-71%) and chemical N fertilizers (range stormwater runoff and that there was a continuum of source changes during the stormwater events. Further, the NO3-N transport in the stormwater runoff from the residential catchment was driven by mixing of multiple sources and biotic (i.e., nitrification) processes. This work suggests that a better understanding of N transport and sources is needed to reduce N export and improve water quality in urban water systems.

Land use effect and hydrological control on nitrate yield in subtropical mountainous watersheds

Directory of Open Access Journals (Sweden)

J.-C. Huang

2012-03-01

Full Text Available Nitrate export in small subtropical watersheds is rarely observed and the estimation of individual land use nitrate yield from a mixed combination within catchments has scarcely been studied. In this study the nitrate concentrations at 16 nested catchments in the Chi-Chia-Wan watershed in Central Taiwan were measured during 2007–2008. A 3-layer TOPMODEL was applied to estimate daily discharge for ungauged sub-catchments. The observed nitrate concentrations and the simulated discharges were used for nitrate flux estimations through four flux methods. Meanwhile, a new deconvolution computation was developed to resolve the nitrate yield of each land use from within the mixed combinations.

The results showed that the observed mean NO₃-N concentration in relatively pristine catchments was approximately 0.145 ± 0.103 mg l⁻¹, which is comparable with other forestry catchments around the world. However, the higher rainfall/runoff, substantial N deposition, and other nitrogen sources resulted in significantly higher annual export of approximately 238–1018 kg-N km⁻² yr⁻¹. Our deconvolution computation showed that the background yield of natural forestry was ~351 ±62 kg-N km⁻² yr⁻¹. On the other hand, the extremely high nitrate yield of active farmland was ~308, 170 ± 19 241 kg-N km⁻² yr⁻¹ due to over-fertilization. The deconvolution computation technique is capable of tracing the mixed signals at the outlet back to the nitrate productions from varied land use patterns. It advances the application of river monitoring network. The typical values of nitrate yields can serve as a guideline for land management. Comparing the nitrogen input and output, we found some nitrogen missing in the cycling which may indicate certain removal processes and we therefore suggest further study to be carried out to fully understand nitrogen cycling in

Total nitrogen and total phosphorus removal from brackish aquaculture wastewater using effective microorganism

Science.gov (United States)

Mohamad, K. A.; Mohd, S. Y.; Sarah, R. S.; Mohd, H. Z.; Rasyidah, A.

2017-09-01

Aquaculture is one of dominant food based industry in the world with 8.3% annual growth rate and its development had led to adverse effect on the environment. High nutrient production in form of nitrogenous compound and phosphorus contributed to environmental deterioration such as eutrophication and toxicity to the industry. Usage of Effective Microorganism (EM), one of the biological approaches to remove Total Nitrogen (TN) and Total Phosphorus (TP) in aquaculture pond was proposed. Samples were obtained from the Sea Bass intensive brackish aquaculture wastewater (AW) from fish farm at Juru, Penang and the parameters used to measure the removal of nitrogenous compounds include, pH, EM dosage, shaking, contact time and optimum variable conditions. From the study, for effective contact time, day 6 is the optimum contact time for both TN and TP with 99.74% and 62.78% removal respectively while in terms of optimum pH, the highest TN removal was at pH 7 with 66.89 %. The optimum dosage of EM is 1.5 ml with ratio 1:166 for 81.5 % TN removal was also found appropriate during the experiment. At varied optimum conditions of EM, the removal efficiency of TN and TP were 81.53% and 38.94% respectively while the removal mechanism of TN was highly dependent on the decomposition rate of specific bacteria such as Nitrobacter bacteria, Yeast and Bacillus Subtilis sp. The study has established the efficacy of EM's ability to treat excessive nutrient of TN and TP from AW.

Development of technology for ammonium nitrate dissociation process

International Nuclear Information System (INIS)

Zakharkin, B.S.; Varykhanov, V.P.; Kucherenko, V.S.; Solov'yeva, L.N.; Revyakin, V.V.

2000-01-01

Ammonia and ammonium carbonate are frequently used as reagents in fuel production and processing of liquid radioactive wastes. In particular, liquid radioactive wastes that contain ammonium nitrate are generated during operations of metal precipitation. In closed vessels at elevated temperature, for example in evaporators or deposits in tubing, ammonium nitrate may explode due to generation of gaseous nitrogen oxides [2]. In this connection, steps have to be taken to rule out conditions that result in explosion. To do that, ammonium nitrate should be removed even prior to the initial stage of its formation. This report gives results of development of a method of dissociating ammonium nitrate

Nitrate-dependent iron oxidation limits iron transport in anoxic ocean regions

Science.gov (United States)

Scholz, Florian; Löscher, Carolin R.; Fiskal, Annika; Sommer, Stefan; Hensen, Christian; Lomnitz, Ulrike; Wuttig, Kathrin; Göttlicher, Jörg; Kossel, Elke; Steininger, Ralph; Canfield, Donald E.

2016-11-01

Iron is an essential element for life on Earth and limits primary production in large parts of the ocean. Oxygen-free continental margin sediments represent an important source of bioavailable iron to the ocean, yet little of the iron released from the seabed reaches the productive sea surface. Even in the anoxic water of oxygen minimum zones, where iron solubility should be enhanced, most of the iron is rapidly re-precipitated. To constrain the mechanism(s) of iron removal in anoxic ocean regions we explored the sediment and water in the oxygen minimum zone off Peru. During our sampling campaign the water column featured two distinct redox boundaries separating oxic from nitrate-reducing (i.e., nitrogenous) water and nitrogenous from weakly sulfidic water. The sulfidic water mass in contact with the shelf sediment contained elevated iron concentrations >300 nM. At the boundary between sulfidic and nitrogenous conditions, iron concentrations dropped sharply to <20 nM coincident with a maximum in particulate iron concentration. Within the iron gradient, we found an increased expression of the key functional marker gene for nitrate reduction (narG). Part of this upregulation was related to the activity of known iron-oxidizing bacteria. Collectively, our data suggest that iron oxidation and removal is induced by nitrate-reducing microbes, either enzymatically through anaerobic iron oxidation or by providing nitrite for an abiotic reaction. Given the important role that iron plays in nitrogen fixation, photosynthesis and respiration, nitrate-dependent iron oxidation likely represents a key-link between the marine biogeochemical cycles of nitrogen, oxygen and carbon.

Impact of nitrogen source and supply level on growth, yield and nutritional value of two contrasting ecotypes of Cichorium spinosum L. grown hydroponically.

Science.gov (United States)

Chatzigianni, Martina; Alkhaled, Bara'a; Livieratos, Ioannis; Stamatakis, Aristidis; Ntatsi, Georgia; Savvas, Dimitrios

2018-03-01

In the present study, two contrasting stamnagathi (Cichorium spinosum L.) ecotypes originating either from a mountainous or from a seaside habitat were grown hydroponically and supplied with a nutrient solution differing in the total-N level (4 or 16 mmol L -1 ) and the N source (NH 4 + -N/total-N: 0.05, 0.25 or 0.50). The aim was to search for genotypic differences in nitrogen nutrition. At commercial maturity, the dry weight of mountainous plants was higher than that of seaside plants. The shoot mineral concentrations were higher in seaside plants than in mountainous plants in both harvests. The leaf nitrate concentration was influenced by the levels of both total-N and NH 4 + -N/total-N at both harvests, whereas plants with a seaside origin exhibited higher nitrate concentrations than those originating from a mountainous site in all total-N and NH 4 + -N/total-N treatments. The two stamnagathi ecotypes differed considerably in their responses to nitrogen nutrition and tissue nitrate content. The mountainous ecotype was superior in terms of growth, tissue nitrate concentration and antioxidant capacity, whereas the seaside ecotype accumulated more nutrient microcations in leaves. A low total-N concentration (up to 4 mmol L -1 ) combined with a high NH 4 + -N/total-N ratio (up to 0.05) could minimize tissue NO 3 - concentrations without compromising yield. © 2017 Society of Chemical Industry. © 2017 Society of Chemical Industry.

Rapid cycling of reactive nitrogen in the marine boundary layer.

Science.gov (United States)

Ye, Chunxiang; Zhou, Xianliang; Pu, Dennis; Stutz, Jochen; Festa, James; Spolaor, Max; Tsai, Catalina; Cantrell, Christopher; Mauldin, Roy L; Campos, Teresa; Weinheimer, Andrew; Hornbrook, Rebecca S; Apel, Eric C; Guenther, Alex; Kaser, Lisa; Yuan, Bin; Karl, Thomas; Haggerty, Julie; Hall, Samuel; Ullmann, Kirk; Smith, James N; Ortega, John; Knote, Christoph

2016-04-28

Nitrogen oxides are essential for the formation of secondary atmospheric aerosols and of atmospheric oxidants such as ozone and the hydroxyl radical, which controls the self-cleansing capacity of the atmosphere. Nitric acid, a major oxidation product of nitrogen oxides, has traditionally been considered to be a permanent sink of nitrogen oxides. However, model studies predict higher ratios of nitric acid to nitrogen oxides in the troposphere than are observed. A 'renoxification' process that recycles nitric acid into nitrogen oxides has been proposed to reconcile observations with model studies, but the mechanisms responsible for this process remain uncertain. Here we present data from an aircraft measurement campaign over the North Atlantic Ocean and find evidence for rapid recycling of nitric acid to nitrous acid and nitrogen oxides in the clean marine boundary layer via particulate nitrate photolysis. Laboratory experiments further demonstrate the photolysis of particulate nitrate collected on filters at a rate more than two orders of magnitude greater than that of gaseous nitric acid, with nitrous acid as the main product. Box model calculations based on the Master Chemical Mechanism suggest that particulate nitrate photolysis mainly sustains the observed levels of nitrous acid and nitrogen oxides at midday under typical marine boundary layer conditions. Given that oceans account for more than 70 per cent of Earth's surface, we propose that particulate nitrate photolysis could be a substantial tropospheric nitrogen oxide source. Recycling of nitrogen oxides in remote oceanic regions with minimal direct nitrogen oxide emissions could increase the formation of tropospheric oxidants and secondary atmospheric aerosols on a global scale.

Nitrogen removal and nitrate leaching for two perennial, sod-based forage systems receiving dairy effluent.

Science.gov (United States)

Woodard, Kenneth R; French, Edwin C; Sweat, Lewin A; Graetz, Donald A; Sollenberger, Lynn E; Macoon, Bisoondat; Portier, Kenneth M; Rymph, Stuart J; Wade, Brett L; Prine, Gordon M; Van Horn, Harold H

2003-01-01

In northern Florida, year-round forage systems are used in dairy effluent sprayfields to reduce nitrate leaching. Our purpose was to quantify forage N removal and monitor nitrate N (NO3(-)-N) concentration below the rooting zone for two perennial, sod-based, triple-cropping systems over four 12-mo cycles (1996-2000). The soil is an excessively drained Kershaw sand (thermic, uncoated Typic Quartzip-samment). Effluent N rates were 500, 690, and 910 kg ha(-1) per cycle. Differences in N removal between a corn (Zea mays L.)-bermudagrass (Cynodon spp.)-rye (Secale cereale L.) system (CBR) and corn-perennial peanut (Arachis glabrata Benth.)-rye system (CPR) were primarily related to the performance of the perennial forages. Nitrogen removal of corn (125-170 kg ha(-1)) and rye (62-90 kg ha(-1)) was relatively stable between systems and among cycles. The greatest N removal was measured for CBR in the first cycle (408 kg ha(-1)), with the bermudagrass removing an average of 191 kg N ha(-1). In later cycles, N removal for bermudagrass declined because dry matter (DM) yield declined. Yield and N removal of perennial peanut increased over the four cycles. Nitrate N concentrations below the rooting zone were lower for CBR than CPR in the first two cycles, but differences were inconsistent in the latter two. The CBR system maintained low NO3(-)-N leaching in the first cycle when the bermudagrass was the most productive; however, it was not a sustainable system for long-term prevention of NO3(-)-N leaching due to declining bermudagrass yield in subsequent cycles. For CPR, effluent N rates > or = 500 kg ha(-1) yr(-1) have the potential to negatively affect ground water quality.

Determination of 15N nitrates in water samples using mass spectrometry

International Nuclear Information System (INIS)

Moya, P.; Aguirre, E.; Gallardo, P.

2000-01-01

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

Depletion of carbohydrate reserves limits nitrate uptake during early regrowth in Lolium perenne L.

Czech Academy of Sciences Publication Activity Database

Guo, Q.; Turnbull, M.; Song, J.; Roche, J.; Novák, Ondřej; Späth, J.; Jameson, P. E.; Love, J.

2017-01-01

Roč. 68, č. 7 (2017), s. 1569-1583 ISSN 0022-0957 R&D Projects: GA ČR(CZ) GA17-06613S Institutional support: RVO:61389030 Keywords : Carbohydrate * Carbon * Cytokinin * Fructan * Lolium perenne * Nitrate transporter (NRT) * Nitrate uptake * Nitrogen * Nitrogen use efficiency (NUE) * Perennial ryegrass Subject RIV: EF - Botanics OBOR OECD: Plant sciences, botany Impact factor: 5.830, year: 2016

[Effects of nitrogen application rate on nitrate reductase activity, nitric oxide content and gas exchange in winter wheat leaves].

Science.gov (United States)

Shangguan, Zhou-Ping

2007-07-01

In this paper, the effects of different nitrogen application rates on the nitrate reductase (NR) activity, nitric oxide (NO) content and gas exchange parameters in winter wheat (Triticum aestivum L.) leaves from tillering stage to heading stage and on grain yield were studied. The results showed that the photosynthetic rate (P(n)), transpiration rate (T(r)) and instantaneous water use efficiency (IWUE) of leaves as well as the grain yield were increased with increasing nitrogen application rate first but decreased then, with the values of all these parameters reached the highest in treatment N180. The NR activity increased with increasing nitrogen application rate, and there was a significant linear correlation between NR activity and NO content at tillering and jointing stages (R2 > or = 0.68, n = 15). NO content had a quadratic positive correlation with stomatal conductance (G(s)) (R2 > or = 0.43, n = 15). The lower NO content produced by lower NR activity under lower nitrogen application rate promoted the stoma opened, while the higher NO content produced by higher NR activity under higher nitrogen application rate induced the stoma closed. Although the leaf NO content had a quadratic positive correlation with stomatal conductance (R2 > or = 0.36, n = 15), no remarkable correlation was observed between NR activity and NO content at heading stage, suggesting that nitrogen fertilization could not affect leaf NO content through promoting NR activity, and further more, regulate the stomatal action. Under appropriate nitrogen application the leaf NR activity and NO content were lower, G(s), T(r) and IWUE were higher, and thus, the crop had a better drought-resistant ability, higher P(n), and higher grain yield.

Nitrogen recycling from fuel-extracted algal biomass: residuals as the sole nitrogen source for culturing Scenedesmus acutus.

Science.gov (United States)

Gu, Huiya; Nagle, Nick; Pienkos, Philip T; Posewitz, Matthew C

2015-05-01

In this study, the reuse of nitrogen from fuel-extracted algal residues was investigated. The alga Scenedesmus acutus was found to be able to assimilate nitrogen contained in amino acids, yeast extracts, and proteinaceous alga residuals. Moreover, these alternative nitrogen resources could replace nitrate in culturing media. The ability of S. acutus to utilize the nitrogen remaining in processed algal biomass was unique among the promising biofuel strains tested. This alga was leveraged in a recycling approach where nitrogen is recovered from algal biomass residuals that remain after lipids are extracted and carbohydrates are fermented to ethanol. The protein-rich residuals not only provided an effective nitrogen resource, but also contributed to a carbon "heterotrophic boost" in subsequent culturing, improving overall biomass and lipid yields relative to the control medium with only nitrate. Prior treatment of the algal residues with Diaion HP20 resin was required to remove compounds inhibitory to algal growth. Copyright © 2014 Elsevier Ltd. All rights reserved.

Nitrate in Danish groundwater during the last 60 years

DEFF Research Database (Denmark)

Hansen, B; Thorling, L; Dalgaard, Tommy

2011-01-01

This presentation assesses the long-term development in the oxic groundwater nitrate concentration and nitrogen (N) loss due to intensive farming in Denmark. Firstly, up to 20-year time-series from the national groundwater monitoring network enable a statistically systematic analysis of distribut......This presentation assesses the long-term development in the oxic groundwater nitrate concentration and nitrogen (N) loss due to intensive farming in Denmark. Firstly, up to 20-year time-series from the national groundwater monitoring network enable a statistically systematic analysis...... of distribution, trends and trend reversals in the groundwater nitrate concentration. Secondly, knowledge about the N surplus in Danish agriculture since 1950 is used as an indicator of the potential loss of N. Thirdly, groundwater recharge CFC (Chlorofluorocarbon) age determination allows linking of the first...... two dataset. The development in the nitrate concentration of oxic groundwater clearly mirrors the development in the national agricultural N surplus, and a corresponding trend reversal is found in groundwater (see Figure 1). Regulation and technical improvements in the intensive farming in Denmark...

Impact of Front Range sources on reactive nitrogen concentrations and deposition in Rocky Mountain National Park

Directory of Open Access Journals (Sweden)

Katherine B. Benedict

2018-05-01

Full Text Available Human influenced atmospheric reactive nitrogen (RN is impacting ecosystems in Rocky Mountain National Park (ROMO. Due to ROMO’s protected status as a Class 1 area, these changes are concerning, and improving our understanding of the contributions of different types of RN and their sources is important for reducing impacts in ROMO. In July–August 2014 the most comprehensive measurements (to date of RN were made in ROMO during the Front Range Air Pollution and Photochemistry Éxperiment (FRAPPÉ. Measurements included peroxyacetyl nitrate (PAN, C1–C5 alkyl nitrates, and high-time resolution NOx, NOy, and ammonia. A limited set of measurements was extended through October. Co-located measurements of a suite of volatile organic compounds provide information on source types impacting ROMO. Specifically, we use ethane as a tracer of oil and gas operations and tetrachloroethylene (C2Cl4 as an urban tracer to investigate their relationship with RN species and transport patterns. Results of this analysis suggest elevated RN concentrations are associated with emissions from oil and gas operations, which are frequently co-located with agricultural production and livestock feeding areas in the region, and from urban areas. There also are periods where RN at ROMO is impacted by long-range transport. We present an atmospheric RN budget and a nitrogen deposition budget with dry and wet components. Total deposition for the period (7/1–9/30 was estimated at 1.58 kg N/ha, with 87% from wet deposition during this period of above average precipitation. Ammonium wet deposition was the dominant contributor to total nitrogen deposition followed by nitrate wet deposition and total dry deposition. Ammonia was estimated to be the largest contributor to dry deposition followed by nitric acid and PAN (other species included alkyl nitrates, ammonium and nitrate. All three species are challenging to measure routinely, especially at high time resolution.

Nitrogen biogeochemistry in the oligohaline zone of a New England estuary

Energy Technology Data Exchange (ETDEWEB)

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

2000-02-01

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

Temporal and spatial variation of nitrogen transformations in a coniferous soil.

NARCIS (Netherlands)

Laverman, A.M.; Zoomer, H.R.; van Verseveld, H.W.; Verhoef, H.A.

2000-01-01

Forest soils show a great degree of temporal and spatial variation of nitrogen mineralization. The aim of the present study was to explain temporal variation in nitrate leaching from a nitrogen-saturated coniferous forest soil by potential nitrification, mineralization rates and nitrate uptake by

Too much of a good thing? Nitrate from nitrogen fertilizers and cancer.

Science.gov (United States)

Ward, Mary H

2009-01-01

Nitrate levels in water supplies have been increasing in many areas of the world; therefore, additional studies of populations with well-characterized exposures are urgently needed to further our understanding of cancer risk associated with nitrate ingestion. Future studies should assess exposure for individuals (e.g., case-control, cohort studies) in a time frame relevant to disease development, and evaluate factors affecting nitrosation. Estimating N-nitroso compounds formation via nitrate ingestion requires information on dietary and drinking water sources of nitrate, inhibitors of nitrosation (e.g., vitamin C), nitrosation precursors (e.g., red meat, nitrosatable drugs), and medical conditions that may increase nitrosation (e.g., inflammatory bowel disease). Studies should account for the potentially different effects of dietary and water sources of nitrate and should include the population using private wells for whom exposure levels are often higher than public supplies.

Nitrogen speciation in various types of aerosols in spring over the northwestern Pacific Ocean

Directory of Open Access Journals (Sweden)

L. Luo

2016-01-01

Full Text Available The cumulative atmospheric nitrogen deposition has been found to profoundly impact the nutrient stoichiometry of the eastern China seas (ECSs: the Yellow Sea and East China Sea and the northwestern Pacific Ocean (NWPO. In spite of the potential significance of dry deposition in those regions, shipboard observations of atmospheric aerosols remain insufficient, particularly regarding the compositions of water-soluble nitrogen species (nitrate, ammonium and water-soluble organic nitrogen – WSON. We conducted a cruise covering the ECSs and the NWPO during the spring of 2014 and observed three types of atmospheric aerosols. Aluminum content, air mass backward trajectories, weather conditions, and ion stoichiometry allowed us to discern dust aerosol patches and sea-fog-modified aerosols (widespread over the ECSs from background aerosols (open ocean. Among the three types, sea-fog-modified aerosols contained the highest concentrations of nitrate (536 ± 300 nmol N m−3, ammonium (442 ± 194 nmol N m−3 and WSON (147 ± 171 nmol N m−3; furthermore, ammonium and nitrate together occupied  ∼  65 % of the molar fraction of total ions. The dust aerosols also contained significant amounts of nitrate (100 ± 23 nmol N m−3 and ammonium (138 ± 24 nmol N m−3 which were obviously larger than those in the background aerosols (26 ± 32 for nitrate and 54 ± 45 nmol N m−3 for ammonium, yet this was not the case for WSON. It appeared that dust aerosols had less of a chance to come in contact with WSON during their transport. In the open ocean, we found that sea salt (e.g., Na+, Cl−, Mg2+, as well as WSON, correlated positively with wind speed. Apparently, marine dissolved organic nitrogen (DON was emitted from breaking waves. Regardless of the variable wind speeds from 0.8 to as high as 18 m s−1, nitrate and ammonium, by contrast, remained in narrow ranges, implying that

Induction of the Nitrate Assimilation nirA Operon and Protein-Protein Interactions in the Maturation of Nitrate and Nitrite Reductases in the Cyanobacterium Anabaena sp. Strain PCC 7120.

Science.gov (United States)

Frías, José E; Flores, Enrique

2015-07-01

Nitrate is widely used as a nitrogen source by cyanobacteria, in which the nitrate assimilation structural genes frequently constitute the so-called nirA operon. This operon contains the genes encoding nitrite reductase (nirA), a nitrate/nitrite transporter (frequently an ABC-type transporter; nrtABCD), and nitrate reductase (narB). In the model filamentous cyanobacterium Anabaena sp. strain PCC 7120, which can fix N2 in specialized cells termed heterocysts, the nirA operon is expressed at high levels only in media containing nitrate or nitrite and lacking ammonium, a preferred nitrogen source. Here we examined the genes downstream of the nirA operon in Anabaena and found that a small open reading frame of unknown function, alr0613, can be cotranscribed with the operon. The next gene in the genome, alr0614 (narM), showed an expression pattern similar to that of the nirA operon, implying correlated expression of narM and the operon. A mutant of narM with an insertion mutation failed to produce nitrate reductase activity, consistent with the idea that NarM is required for the maturation of NarB. Both narM and narB mutants were impaired in the nitrate-dependent induction of the nirA operon, suggesting that nitrite is an inducer of the operon in Anabaena. It has previously been shown that the nitrite reductase protein NirA requires NirB, a protein likely involved in protein-protein interactions, to attain maximum activity. Bacterial two-hybrid analysis confirmed possible NirA-NirB and NarB-NarM interactions, suggesting that the development of both nitrite reductase and nitrate reductase activities in cyanobacteria involves physical interaction of the corresponding enzymes with their cognate partners, NirB and NarM, respectively. Nitrate is an important source of nitrogen for many microorganisms that is utilized through the nitrate assimilation system, which includes nitrate/nitrite membrane transporters and the nitrate and nitrite reductases. Many cyanobacteria

Effect of residual nitrogen and fertilizer nitrogen on sugar beet production in Finland

Directory of Open Access Journals (Sweden)

Veikko Brummer

1974-09-01

Full Text Available Preliminary determinations for NO3- and NH4-N in topsoil from nitrogen field experiments are discussed. The amounts of residual nitrogen as well as the dates and depth for sampling are considerd in order to investigate the need of fertilizer-N for continuous sugar beet. Tops ploughed down as manure increased the available soil nitrogen by about 50 kg/ha. In practice nitrogen from fertilizer and farmyard manure given to previous beet crops seems to accumulate in the beet soils of Finland. The concentrations of nitrate and ammonium nitrogen in topsoil were low in the spring of 1972 and 1973. NO3-N increased in topsoil during the early summer, and the highest concentrations were found at the beginning of July. Starting from the middle of July the amount of NH4-N began to increase both in topsoil and in subsoil. With increasing amounts of nitrogen in the topsoil the sugar content decreases continuously. Also the α-amio N content of beets correlates with the soil nitrogen. There is experimental evidence that 150 180 kg/ha nitrate nitrogen in topsoil (residual + fertilizer N in early July gives the best economic result. The effects of fertilizer and accumulated soil nitrogen on the sugar beet quality together with som other experimental data have been statistically analysed. Regression coefficients indicated that both forms of nitrogen affected the suger content, the α-amino N concentration and clear juice purity, in a similar way.

Tracing the source and fate of nitrate in contemporary mixed land-use surface water systems

Science.gov (United States)

Stewart, S. D.; Young, M. B.; Horton, T. W.; Harding, J. S.

2011-12-01

Nitrogenous fertilizers increase agricultural productivity, ultimately feeding the planet. Yet, it is possible to have too much of a good thing, and nitrogen is no exception. When in excess nitrogen has been shown to accelerate eutrophication of water bodies, and act as a chronic toxin (e.g. methemoglobinemia). As land-use intensity continues to rise in response to increases in agricultural productivity, the risk of adverse effects of nitrogen loading on surface water bodies will also increase. Stable isotope proxies are potential tracers of nitrate, the most common nitrogenous phase in surface waters. Applying stable isotope proxies therefore presents an opportunity to identify and manage sources of excess nitrogen before aquatic systems are severely degraded. However, the heterogeneous nature of potential pollution sources themselves, and their distribution with a modified catchment network, make understanding this issue highly complex. The Banks Peninsula, an eroded late tertiary volcanic complex located on the east coast of the South Island New Zealand, presents a unique opportunity to study and understand the sources and fates of nitrate within streams in a contemporary mixed land-use setting. Within this small geographic area there a variety of agricultural activities are practiced, including: heavily fertilized golf courses; stands of regenerating native forest; and areas of fallow gorse (Ulex europaeus; a invasive N-fixing shrub). Each of these landuse classes has its own unique nitrogen budget. Multivariate analysis was used on stream nitrate concentrations to reveal that stream reaches dominated by gorse had significantly higher nitrate concentrations than other land-use classes. Nitrate δ15N & δ18O data from these sites show strong covariance, plotting along a distinct fractionation line (r2 = 0.96). This finding facilitates interpretation of what processes are controlling nitrate concentration within these systems. Further, complementary aquatic

Elimination of nitrate in secondary effluent of wastewater treatment plants by Fe0 and Pd-Cu/diatomite

Directory of Open Access Journals (Sweden)

Yupan Yun

2018-03-01

Full Text Available Because total nitrogen (TN, in which nitrate (NO3– is dominant in the effluent of most wastewater treatment plants, cannot meet the requirement of Chinese wastewater discharge standard (<15 mg/L, NO3– elimination has attracted considerable attention. In this research, the novel diatomite-supported palladium-copper catalyst (Pd-Cu/diatomite with zero-valent iron (Fe0 was tried to use for catalytic reduction of nitrate in wastewater. Firstly, specific operational conditions (such as mass ratio of Pd:Cu, catalyst amounts, reaction time and pH of solution were optimized for nitrate reduction in artificial solution. Secondly, the selected optimal conditions were further employed for nitrate elimination of real effluent of a wastewater treatment plant in Beijing, China. Results showed that 67% of nitrate removal and 62% of N2 selectivity could be obtained under the following conditions: 5 g/L Fe0, 3:1 mass ratio (Pd:Cu, 4 g/L catalyst, 2 h reaction time and pH 4.3. Finally, the mechanism of catalytic nitrate reduction was also proposed.

High performance of nitrogen and phosphorus removal in an electrolysis-integrated biofilter.

Science.gov (United States)

Gao, Y; Xie, Y W; Zhang, Q; Yu, Y X; Yang, L Y

A novel electrolysis-integrated biofilter system was developed in this study to evaluate the intensified removal of nitrogen and phosphorus from contaminated water. Two laboratory-scale biofilter systems were established, one with electrolysis (E-BF) and one without electrolysis (BF) as control. The dynamics of intensified nitrogen and phosphorus removal and the changes of inflow and outflow water qualities were also evaluated. The total nitrogen (TN) removal rate was 94.4% in our newly developed E-BF, but only 74.7% in the control BF. Ammonium removal rate was up to 95% in biofilters with or without electrolysis integration with an influent ammonium concentration of 40 mg/L, and the accumulation of nitrate and nitrite was much lower in the effluent of E-BF than that of BF. Thus electrolysis plays an important role in TN removal especially the nitrate and nitrite removal. Phosphorus removal was significantly enhanced, exceeding 90% in E-BF by chemical precipitation, physical adsorption, and flocculation of phosphorus because of the in situ formation of ferric ions by the anodizing of sacrificial iron anodes. Results from this study indicate that the electrolysis integrated biofilter is a promising solution for intensified nitrogen and phosphorus removal.

Nitrogen transformations in stratified aquatic microbial ecosystems

DEFF Research Database (Denmark)

Revsbech, Niels Peter; Risgaard-Petersen, N.; Schramm, Andreas

2006-01-01

Abstract  New analytical methods such as advanced molecular techniques and microsensors have resulted in new insights about how nitrogen transformations in stratified microbial systems such as sediments and biofilms are regulated at a µm-mm scale. A large and ever-expanding knowledge base about n...... performing dissimilatory reduction of nitrate to ammonium have given new dimensions to the understanding of nitrogen cycling in nature, and the occurrence of these organisms and processes in stratified microbial communities will be described in detail.......Abstract  New analytical methods such as advanced molecular techniques and microsensors have resulted in new insights about how nitrogen transformations in stratified microbial systems such as sediments and biofilms are regulated at a µm-mm scale. A large and ever-expanding knowledge base about...... nitrogen fixation, nitrification, denitrification, and dissimilatory reduction of nitrate to ammonium, and about the microorganisms performing the processes, has been produced by use of these techniques. During the last decade the discovery of anammmox bacteria and migrating, nitrate accumulating bacteria...

The Nitrate/Perchlorate Ratio on Mars as an Indicator for Habitability

Science.gov (United States)

Stern, J. C.; Sutter, B.; McKay, C. P.; Navarro-Gonzalex, R.; Freissinet, C.; Conrad, P. G.; Mahaffy, P. R.; Archer, P. D., Jr.; Ming, D. W.; Niles, P. B.;

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

International Nuclear Information System (INIS)

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

2017-01-01

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

Modeling nitrate from land surface to wells' perforations under agricultural land: success, failure, and future scenarios in a Mediterranean case study

Science.gov (United States)

Levy, Yehuda; Shapira, Roi H.; Chefetz, Benny; Kurtzman, Daniel

2017-07-01

Contamination of groundwater resources by nitrate leaching under agricultural land is probably the most troublesome agriculture-related water contamination worldwide. Contaminated areas often show large spatial variability of nitrate concentration in wells. In this study, we tried to assess whether this spatial variability can be characterized on the basis of land use and standard agricultural practices. Deep soil sampling (10 m) was used to calibrate vertical flow and nitrogen-transport numerical models of the unsaturated zone under different agricultural land uses. Vegetable fields (potato and strawberry) and deciduous orchards (persimmon) in the Sharon area overlying the coastal aquifer of Israel were examined. Average nitrate-nitrogen fluxes below vegetable fields were 210-290 kg ha-1 yr-1 and under deciduous orchards were 110-140 kg ha-1 yr-1. The output water and nitrate-nitrogen fluxes of the unsaturated-zone models were used as input data for a three-dimensional flow and nitrate-transport model in the aquifer under an area of 13.3 km2 of agricultural land. The area was subdivided into four agricultural land uses: vegetables, deciduous orchards, citrus orchards, and non-cultivated. Fluxes of water and nitrate-nitrogen below citrus orchards were taken from a previous study in the area. The groundwater flow model was calibrated to well heads by changing the hydraulic conductivity. The nitrate-transport model, which was fed by the above-mentioned models of the unsaturated zone, succeeded in reconstructing the average nitrate concentration in the wells. However, this transport model failed in calculating the high concentrations in the most contaminated wells and the large spatial variability of nitrate concentrations in the aquifer. To reconstruct the spatial variability and enable predictions, nitrate fluxes from the unsaturated zone were multiplied by local multipliers. This action was rationalized by the fact that the high concentrations in some wells cannot

Nitrous oxide emission by the non-denitrifying, nitrate ammonifier Bacillus licheniformis

OpenAIRE

Sun, Yihua; De Vos, Paul; Heylen, Kim

2016-01-01

Background Firmicutes have the capacity to remove excess nitrate from the environment via either denitrification, dissimilatory nitrate reduction to ammonium or both. The recent renewed interest in their nitrogen metabolism has revealed many interesting features, the most striking being their wide variety of dissimilatory nitrate reduction pathways. In the present study, nitrous oxide production from Bacillus licheniformis, a ubiquitous Gram-positive, spore-forming species with many industria...

Recycling soil nitrate nitrogen by amending agricultural lands with oily food waste.

Science.gov (United States)

Rashid, M T; Voroney, R P

2003-01-01

With current agricultural practices the amounts of fertilizer N applied are frequently more than the amounts removed by the crop. Excessive N application may result in short-term accumulation of nitrate nitrogen (NO3-N) in soil, which can easily be leached from the root zone and into the ground water. A management practice suggested for conserving accumulated NO3-N is the application of oily food waste (FOG; fat + oil + greases) to agricultural soils. A two-year field study (1995-1996 and 1996-1997) was conducted at Elora Research Center (43 degrees 38' N, 80 degrees W; 346 m above mean sea level), University of Guelph, Ontario, Canada to determine the effect of FOG application in fall and spring on soil NO3-N contents and apparent N immobilization-mineralization of soil N in the 0- to 60-cm soil layer. The experiment was planned under a randomized complete block design with four replications. An unamended control and a reference treatment [winter wheat (Triticum aestivum L.) cover crop] were included in the experiment to compare the effects of fall and spring treatment of oily food waste on soil NO3-N contents and apparent N immobilization-mineralization. Oily food waste application at 10 Mg ha(-1) in the fall decreased soil NO3-N by immobilization and conserved 47 to 56 kg NO3-N ha(-1), which would otherwise be subject to leaching. Nitrogen immobilized due to FOG application in the fall was subsequently remineralized by the time of fertilizer N sidedress, whereas no net mineralization was observed in spring-amended plots at the same time.

Dual Nitrate Isotopes in Dry Deposition: Utility for Partitioning Nox Source Contributions to Landscape Nitrogen Deposition

Science.gov (United States)

Dry deposition is a major component of total nitrogen deposition and thus an important source of bioavailable nitrogen to ecosystems. However, relative to wet deposition, less is known regarding the sources and spatial variability of dry deposition. This is in part due to diffi...

Nitrogen use strategies of seedlings from neotropical tree species of distinct successional groups.

Science.gov (United States)

Oliveira, Halley Caixeta; da Silva, Ligia Maria Inocêncio; de Freitas, Letícia Dias; Debiasi, Tatiane Viegas; Marchiori, Nidia Mara; Aidar, Marcos Pereira Marinho; Bianchini, Edmilson; Pimenta, José Antonio; Stolf-Moreira, Renata

2017-05-01

Few studies have analyzed the strategies of neotropical tree seedlings for absorbing, translocating and assimilating the nitrogen. Here, we compared the nitrogen use strategies of seedlings from six tree species that are native to the Brazilian Atlantic Forest and that belong to different successional groups: Trema micrantha, Heliocarpus popayanensis and Cecropia pachystachya (pioneers), Cariniana estrellensis, Eugenia brasiliensis and Guarea kunthiana (non-pioneers). The effects of cultivating seedlings with nitrate or ammonium on the growth, physiology and nitrogen metabolism were analyzed. Nitrate-grown pioneer species had much higher leaf nitrate reductase activity than non-pioneer ones, but non-pioneer seedlings were also able to use nitrate as a nitrogen source. In addition to this remarkable difference between the groups in the capacity for leaf nitrate assimilation, substantial variations in the nitrogen use strategies were observed within the successional classes. Differently from the other non-pioneers, the canopy species C. estrellensis seemed to assimilate nitrate mainly in the leaves. Morphophysiological analyses showed a gradient of ammonium toxicity response, with E. brasiliensis as the most tolerant species, and T. micrantha and H. popayanensis as the most sensitive ones. Guarea kunthiana showed a relatively low tolerance to ammonium and an unusual high translocation of this cation in the xylem sap. In contrast to the other pioneers, C. pachystachya had a high plasticity in the use of nitrogen sources. Overall, these results suggest that nitrogen use strategies of neotropical tree seedlings were not determined solely by their successional position. Copyright © 2017 Elsevier Masson SAS. All rights reserved.

Comparative changes in monthly blood urea nitrogen, total protein ...

African Journals Online (AJOL)

The objective of this study was to determine the comparative changes in the monthly blood urea nitrogen (BUN) concentration, total protein (TP) concentration in blood serum and the body condition score of Nguni cows and heifers raised on sweetveld. Twenty-four clinically healthy animals in different parities, namely Parity ...

Investigation on the photoreactions of nitrate and nitrite ions with selected azaarenes in water

Science.gov (United States)

Beitz; Bechmann; Mitzner

1999-01-01

The photoreactions of selected azaarenes with nitrate and nitrite ions were investigated under irradiation at lambda = 313 nm. The excitation of both anions leads to several photochemical reactions forming mainly hydroxyl radicals and nitrogen oxides. The purification capability of natural waters i.e. the oxidation of inorganic and organic substances results from the formation of hydroxyl radicals. Nitrated isomers of azaarenes were found among the main products of the investigated photoreactions. The nitrogen oxides were responsible for the production of nitrated derivatives which possess a high toxic potential. Their formation was explained by the parallel occurance of two mechanism, a molecular and a radical one. The molecular mechanism became more important with increasing ionisation potentials of the azaarenes. The spectrum of oxidized products corresponded to the one got in the photoreactions of azaarenes with hydrogen peroxide. The formation of several oxidation and nitration products of the pyridine ring with its low electron density was explained by the reaction of excited states of azaarenes. The photoreactions with nitrite ions only led to the formation of oxidized and nitrated products. Nitroso products were not formed. The reactivity of nitrogen monoxide is too low for its reaction with the azaarenes.

Checking Trace Nitrate in Water and Soil Using an Amateur Scientist's Measurement Guide.

Science.gov (United States)

Baker, Roger C. Jr.

1995-01-01

Presents a test that can measure nitrate nitrogen ions at about 0.1 mg/L using concentration. Uses inexpensive accessible materials and can be used by amateur environmentalists for monitoring water nitrate levels. (JRH)

Electrochemical reduction of nitrate in the presence of an amide

Science.gov (United States)

Dziewinski, Jacek J.; Marczak, Stanislaw

2002-01-01

The electrochemical reduction of nitrates in aqueous solutions thereof in the presence of amides to gaseous nitrogen (N.sub.2) is described. Generally, electrochemical reduction of NO.sub.3 proceeds stepwise, from NO.sub.3 to N.sub.2, and subsequently in several consecutive steps to ammonia (NH.sub.3) as a final product. Addition of at least one amide to the solution being electrolyzed suppresses ammonia generation, since suitable amides react with NO.sub.2 to generate N.sub.2. This permits nitrate reduction to gaseous nitrogen to proceed by electrolysis. Suitable amides include urea, sulfamic acid, formamide, and acetamide.

Evaluating Chemical Tracers in Suburban Groundwater as Indicators of Nitrate-Nitrogen Sources

Science.gov (United States)

Nitka, A.; DeVita, W. M.; McGinley, P.

2015-12-01

The CDC reports that over 15 million US households use private wells. These wells are vulnerable to contamination. One of the most common contaminants in private wells is nitrate. Nitrate has a health standard of 10 mg/L. This standard is set to prevent methemaglobinemia, or "blue baby" syndrome, in infants. In extreme cases it can affect breathing and heart function, and even lead to death. Elevated nitrate concentrations have also been associated with increased risk of thyroid disease, diabetes, and certain types of cancer. Unlike municipal wells, there is no mandatory testing of private wells. It is the responsibility of users to have their well water tested. The objective of this research was to identify the most useful chemical tracers for determining sources of nitrate in private water supplies. Chemical characteristics, such as mobility in groundwater and water solubility, as well as frequency of use, were considered when choosing source indicators. Fourteen pharmaceuticals and personal care products unique to human use were chosen to identify wells impacted by septic waste. A bovine antibiotic and five pesticide metabolites were used to identify contamination from agricultural sources. Eighteen private wells were selected in a suburban area with septic systems and adjacent agricultural land. The wells were sampled five times and analyzed to provide a temporal profile of nitrate and the tracers. The artificial sweetener sucralose was found in >70% of private wells. Wells with sucralose detected had nitrate concentrations between 5-15 mg/L. The herbicide metabolite metolachlor ESA was detected in 50% of the wells. These wells typically had the highest nitrate concentrations, often >10 mg/L. The common use and frequent detection of these two compounds made them the most reliable indicators of nitrate sources evaluated in this study. This information will help well owners determine appropriate treatment and remediation options and could direct future

The effect of nitrogen and sulphur fertilization on the yield and content of sulforaphane and nitrates in cauliflower

Directory of Open Access Journals (Sweden)

Nina Čekey

2011-01-01

Full Text Available In the field experiment with cauliflower, we investigated the effect of four different variants of nitrogen and suplhur fertilization on quantity and quality of cauliflower in the term of sulforaphane content and nitrate accumulation. The influence of fertilization was statistically significant between control variant and fertilization variants and in both experimental years within all parameters of cauliflower yield. The highest yield of cauliflower was reached at the variant 4 when it was fertilized on the level of nutrients N:S = 250:60 kg.ha−1. The increase of yield against control variant represented value 26.6%. The applied fertilization positively affected on the accumulation sulforaphane in the cauliflower. Its highest content was determined at the variant 4 (N:S = 250:60 kg.ha−1. In comparison with control variant, the sulforaphane content was increased about 18.4%. On the other side, applied nutrition resulted in increased accumulation of nitrates in the cauliflower. The most increase of nitrate content, compared to the control variant, was also ascertained at the variant 4 (about 31.4%.The gathered data point towards to the possibility and way how we could effect on the increased accumulation of sulforaphane in cauliflower florets. This sphere of fertilization effect on the sulforaphane content is not sufficiently explored well. Our aim is to continue in this research subject and to find way how to cultivate vegetables with higher content of health-promoting compounds.

Modeling the long-term fate of agricultural nitrate in groundwater in the San Joaquin Valley, California

Science.gov (United States)

Chapelle, Francis H.; Campbell, Bruce G.; Widdowson, Mark A.; Landon, Mathew K.

2013-01-01

Nitrate contamination of groundwater systems used for human water supplies is a major environmental problem in many parts of the world. Fertilizers containing a variety of reduced nitrogen compounds are commonly added to soils to increase agricultural yields. But the amount of nitrogen added during fertilization typically exceeds the amount of nitrogen taken up by crops. Oxidation of reduced nitrogen compounds present in residual fertilizers can produce substantial amounts of nitrate which can be transported to the underlying water table. Because nitrate concentrations exceeding 10 mg/L in drinking water can have a variety of deleterious effects for humans, agriculturally derived nitrate contamination of groundwater can be a serious public health issue. The Central Valley aquifer of California accounts for 13 percent of all the groundwater withdrawals in the United States. The Central Valley, which includes the San Joaquin Valley, is one of the most productive agricultural areas in the world and much of this groundwater is used for crop irrigation. However, rapid urbanization has led to increasing groundwater withdrawals for municipal public water supplies. That, in turn, has led to concern about how contaminants associated with agricultural practices will affect the chemical quality of groundwater in the San Joaquin Valley. Crop fertilization with various forms of nitrogen-containing compounds can greatly increase agricultural yields. However, leaching of nitrate from soils due to irrigation has led to substantial nitrate contamination of shallow groundwater. That shallow nitrate-contaminated groundwater has been moving deeper into the Central Valley aquifer since the 1960s. Denitrification can be an important process limiting the mobility of nitrate in groundwater systems. However, substantial denitrification requires adequate sources of electron donors in order to drive the process. In many cases, dissolved organic carbon (DOC) and particulate organic carbon

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

International Nuclear Information System (INIS)

Wada, E.; Shibata, R.; Torii, T

1981-01-01

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

Gas phase reactions of nitrogen oxides with olefins

Energy Technology Data Exchange (ETDEWEB)

Altshuller, A P; Cohen, I

1961-01-01

The nature of the condensation products formed in the gas phase reactions of nitrogen dioxide and nitric oxide with pentene-1, 2-methylbutene-2, and 2-methylbutadiene-1,3 was investigated. The reactants were combined at partial pressures in the range of 0.1 to 2.5 mm with the total pressure at one atmosphere. The products were determined by infrared and ultraviolet spectroscopy and colorimetry. The condensates included primary and secondary nitro compounds and alkyl nitrates. Strong hydroxyl and single bond carbon to oxygen stretching vibrations indicate the presence of either nitroalcohols or simple aliphatic alcohols formed through oxidation reactions. Carbonyl stretching frequencies observable in some of the reactions support the conclusion that a portion of the reactants disappear by oxidation rather than by nitration processes. The available results do not indicate the presence of appreciable amounts of tert.-nitro compounds, conjugated nitro-olefins, or gem-dinitro-alkanes. The reactivities of the olefins with the nitrogen oxides are in the decreasing order: 2-methyl-butadiene-1,3, 2-methylbutene-2, pentene-1. 20 references.

CONCENTRATED CALCIUM NITRATE IS AN EFFECTIVE SOLUTION FOR MINERAL NUTRITION OF VEGETABLES GROWN THROUGH PROTECTED CULTIVATION

Directory of Open Access Journals (Sweden)

T. V. Grebennikova

2017-01-01

Full Text Available One of the basis water-soluble fertilizers that are used in greenhouse enterprises is  a Calcium  nitrate,  where  its production  and demand raise. At present time, calcium nitrate is produced  in a granulated and crystaline   form consisted of tetrahydrate, dihydrate and concentrated variants. These forms  are significantly distinguished  by their  chemical  composition.  Besides the  basic  form  of nitrogen – nitrate – there is ammoniacal nitrogen in the composition of Calcium nitrate that is found to be undesirable element, particularly with drip irrigation system in the  greenhouse. The new  product,  calcium  nitrate  has been worked out with minimal content of ammoniacal nitrogen  at  URALCHIM. The study  showed  the  advantages of the product for such characteristics as solubility and time of dissolving. It dissolves 3.4-7 time faster than those of tetrahydrate and dihydrate analogues. At present time, the concentrated  calcium  nitrate is used in many greenhouse  industrial  complexes  and  enterprises,  and has shown its efficiency in practice.

Nitrate removal through combination of nanofiltration and electrocatalysis; Nitratentfernung durch Kombination von Nanofiltration und Elektrokatalyse

Energy Technology Data Exchange (ETDEWEB)

Roehricht, M.; Stadlbauer, E.A.; Happel, H. [Fachhochschule Giessen (Germany). Zentrum fuer Umwelttechnik

1999-07-01

In a new process combination, nitrate-containing ground water is first of all separated by nanofiltration into a concentrate stream (some 25 %) and a largely nitrate-free permeate (75 %). Then the enriched nitrate in the concentrate is converted into nitrogen by means of electrocatalytic nitrate reduction. Whereas, in nanofiltration, a concentration takes place, electrocatalytic nitrate reduction is a process by which nitrate is converted into elemental nitrogen and, thus, removed. Nanofiltration is a membrane separating process making use of 'open' reverse osmosis membranes, which are characterized by high flow but also reduced retention. (orig.) [German] In einer neuen Verfahrenskombination wird das nitrathaltige Grundwasser zuerst durch Nanofiltration in einen Konzentratstrom (ca. 25%) und ein weitgehend nitratfreies Permeat (75%) aufgeteilt. Im Konzentrat wird dann mittels Elektrokatalytischer Nitratreduktion (EKN) das angereicherte Nitrat zu Stickstoff umgewandelt. Waehrend bei der Nanofiltration eine Aufkonzentrierung erfolgt, wird durch die Elektrokatalytische Nitratreduktion das Nitrat in elementaren Stickstoff umgewandelt und so entfernt. Die Nanofiltration ist ein Membrantrennverfahren, bei dem 'offene' Umkehrosmosemembranen eingesetzt werden, die einen hohen Fluss aber auch eine verminderte Rueckhaltung aufweisen. (orig.)

Ingested Nitrate, Disinfection By-products, and Kidney Cancer Risk in Older Women.

Science.gov (United States)

Jones, Rena R; Weyer, Peter J; DellaValle, Curt T; Robien, Kim; Cantor, Kenneth P; Krasner, Stuart; Beane Freeman, Laura E; Ward, Mary H

2017-09-01

N-nitroso compounds formed endogenously after nitrate/nitrite ingestion are animal renal carcinogens. Previous epidemiologic studies of drinking water nitrate did not evaluate other potentially toxic water contaminants, including the suspected renal carcinogen chloroform. In a cohort of postmenopausal women in Iowa (1986-2010), we used historical measurements to estimate long-term average concentrations of nitrate-nitrogen (NO3-N) and disinfection by-products (DBP) in public water supplies. For NO3-N and the regulated DBP (total trihalomethanes [THM] and the sum of five haloacetic acids [HAA5]), we estimated the number of years of exposure above one-half the current maximum contaminant level (>½-MCL NO3-N; >5 mg/L). Dietary intakes were assessed via food frequency questionnaire. We estimated hazard ratios (HRs) and 95% confidence intervals (CIs) with Cox models, and evaluated interactions with factors influencing N-nitroso compound formation. We identified 125 incident kidney cancers among 15,577 women reporting using water from public supplies >10 years. In multivariable models, risk was higher in the 95th percentile of average NO3-N (HRp95vsQ1 = 2.3; CI: 1.2, 4.3; Ptrend = 0.33) and for any years of exposure >½-MCL; adjustment for total THM did not materially change these associations. There were no independent relationships with total THM, individual THMs chloroform and bromodichloromethane, or with haloacetic acids. Dietary analyses yielded associations with high nitrite intake from processed meats but not nitrate or nitrite overall. We found no interactions. Relatively high nitrate levels in public water supplies were associated with increased risk of renal cancer. Our results also suggest that nitrite from processed meat is a renal cancer risk factor.

Estimating Soil Bulk Density and Total Nitrogen from Catchment ...

African Journals Online (AJOL)

Even though data on soil bulk density (BD) and total nitrogen (TN) are essential for planning modern farming techniques, their data availability is limited for many applications in the developing word. This study is designed to estimate BD and TN from soil properties, land-use systems, soil types and landforms in the ...

Effect of nitrates on embryo induction efficiency in cotton ...

African Journals Online (AJOL)

Cotton (Gossypium hirsutum L.) cv Coker-312 callus culture was assessed in terms of its usefulness as a system for investigating the effect of nitrates from different chemical compounds of nitrogen on embryo induction percentage in calli as the plant growth and cell differentiation mainly based on nitrogen. Both sources and ...

Temporal and spatial variation of nitrogen transformations in a coniferous forest soils.

NARCIS (Netherlands)

Laverman, A.M.; Zoomer, H.R.; van Verseveld, H.W.; Verhoef, H.A.

2000-01-01

Forest soils show a great degree of temporal and spatial variation of nitrogen mineralization. The aim of the present study was to explain temporal variation in nitrate leaching from a nitrogen-saturated coniferous forest soil by potential nitrification, mineralization rates and nitrate uptake by

Consequence of absence of nitrate reductase activity on photosynthesis in Nicotiana plumbaginifolia plants

International Nuclear Information System (INIS)

Saux, C.; Lemoine, Y.; Marion-Poll, A.; Valadier, M.H.; Deng, M.; Morot-Gaudry, J.F.

1987-01-01

Chlorate-resistant Nicotiana plumbaginifolia (cv Viviani) mutants were found to be deficient in the nitrate reductase apoprotein (NR - nia). Because they could not grow with nitrate as sole nitrogen source, they were cultivated as graftings on wild-type Nicotiana tabacum plants. The grafts of mutant plants were chlorotic compared to the grafts of wild type. Mutant leaves did not accumulate nitrogen but contained less malate and more glutamine than wild leaves. They exhibited a slight increase of the proportion of the light-harvesting chlorophyll a/b protein complexes and a lowering of the efficiency of energy transfer between these complexes and the active centers. After a 3 second 14 CO 2 pulse, the total 14 C incorporation of the mutant leaves was approximately 20 5 of that of the control. The 14 C was essentially recovered in ribulose bisphosphate in these plants. It was consistent with a decline of ribulose bisphosphate carboxylase activity observed in the mutant. After a 3 second 14 CO 2 pulse followed by a 60 second chase with normal CO 2 , 14 C was mainly accumulated in starch which was labeled more in the mutant than in the wild type. These results confirm the observation that in the nitrate reductase deficient leaves, chloroplasts were loaded with large starch inclusions preceding disorganization of the photosynthetic apparatus

Consequence of absence of nitrate reductase activity on photosynthesis in Nicotiana plumbaginifolia plants

Energy Technology Data Exchange (ETDEWEB)

Saux, C.; Lemoine, Y.; Marion-Poll, A.; Valadier, M.H.; Deng, M.; Morot-Gaudry, J.F.

1987-05-01

Chlorate-resistant Nicotiana plumbaginifolia (cv Viviani) mutants were found to be deficient in the nitrate reductase apoprotein (NR/sup -/ nia). Because they could not grow with nitrate as sole nitrogen source, they were cultivated as graftings on wild-type Nicotiana tabacum plants. The grafts of mutant plants were chlorotic compared to the grafts of wild type. Mutant leaves did not accumulate nitrogen but contained less malate and more glutamine than wild leaves. They exhibited a slight increase of the proportion of the light-harvesting chlorophyll a/b protein complexes and a lowering of the efficiency of energy transfer between these complexes and the active centers. After a 3 second /sup 14/CO/sub 2/ pulse, the total /sup 14/C incorporation of the mutant leaves was approximately 20/sup 5/ of that of the control. The /sup 14/C was essentially recovered in ribulose bisphosphate in these plants. It was consistent with a decline of ribulose bisphosphate carboxylase activity observed in the mutant. After a 3 second /sup 14/CO/sub 2/ pulse followed by a 60 second chase with normal CO/sub 2/, /sup 14/C was mainly accumulated in starch which was labeled more in the mutant than in the wild type. These results confirm the observation that in the nitrate reductase deficient leaves, chloroplasts were loaded with large starch inclusions preceding disorganization of the photosynthetic apparatus.

Validation of nitrogen-nitrate analysis by the chromotropic acid method

Energy Technology Data Exchange (ETDEWEB)

Santos, Ana Claudia O.; Matoso, Erika, E-mail: anaclaudia.oliveira@marinha.mil.br [Centro Tecnológico da Marinha em São Paulo (CTMSP/CEA), Iperó, SP (Brazil). Centro Experimental ARAMAR

2017-07-01

The problems caused by contamination of water bodies demand strict control of disposal in rivers, seas and oceans. Nitrate ion is present in agricultural inputs, which are applied to the soil to boost plant growth. However, excess or indiscriminate use of these products contaminates water bodies, triggering eutrophication of the aquatic ecosystems. Furthermore, due to diseases that can be caused by the ingestion of high levels of nitrate, such as methaemoglobinaemia, nitrate levels should be controlled in drinking waters and effluents. There are several methods for the determination of nitrate, being the chromotropic acid method a simple and low-cost solution. This method consists of acid addition into the sample in the presence of H{sub 2}SO{sub 4}. The absorbance related to the produced yellow color can be measured by a UV-Vis spectrophotometer at 410 nm. In a modified form, this method can be applied to different aqueous matrices by use of other reagents that eliminate interferences. The aim of this study was to validate the nitrate determination method in waters using chromotropic acid. This method is used in Laboratório Radioecológico (LARE) to analyze effluent to comply with Wastewater Controlling Program of Centro Tecnológico da Marinha em São Paulo – Centro Experimental ARAMAR (CTMSP-CEA). The correlation coefficient for the linearity test was 0.9997. The evaluated detection limit was relatively high (LD = 0.045 mgN/L), if compared to ion chromatography, for example, but enough to determine the presence of this ion, considering the maximum limit proposed by the current legislation. The chromotropic acid method showed to be a robust, accurate and precise method, according the parameters used in this work. (author)

Validation of nitrogen-nitrate analysis by the chromotropic acid method

International Nuclear Information System (INIS)

Santos, Ana Claudia O.; Matoso, Erika

2017-01-01

The problems caused by contamination of water bodies demand strict control of disposal in rivers, seas and oceans. Nitrate ion is present in agricultural inputs, which are applied to the soil to boost plant growth. However, excess or indiscriminate use of these products contaminates water bodies, triggering eutrophication of the aquatic ecosystems. Furthermore, due to diseases that can be caused by the ingestion of high levels of nitrate, such as methaemoglobinaemia, nitrate levels should be controlled in drinking waters and effluents. There are several methods for the determination of nitrate, being the chromotropic acid method a simple and low-cost solution. This method consists of acid addition into the sample in the presence of H 2 SO 4 . The absorbance related to the produced yellow color can be measured by a UV-Vis spectrophotometer at 410 nm. In a modified form, this method can be applied to different aqueous matrices by use of other reagents that eliminate interferences. The aim of this study was to validate the nitrate determination method in waters using chromotropic acid. This method is used in Laboratório Radioecológico (LARE) to analyze effluent to comply with Wastewater Controlling Program of Centro Tecnológico da Marinha em São Paulo – Centro Experimental ARAMAR (CTMSP-CEA). The correlation coefficient for the linearity test was 0.9997. The evaluated detection limit was relatively high (LD = 0.045 mgN/L), if compared to ion chromatography, for example, but enough to determine the presence of this ion, considering the maximum limit proposed by the current legislation. The chromotropic acid method showed to be a robust, accurate and precise method, according the parameters used in this work. (author)

Isotopic composition of nitrate in the central Arabian Sea and eastern tropical North Pacific: A tracer for mixing and nitrogen cycles

Digital Repository Service at National Institute of Oceanography (India)

Brandes, J.A.; Devol, A.H.; Yoshinari, T.; Jayakumar, D.A.; Naqvi, S.W.A.

Trench. Ph.D. Thesis, Univ. of Cali- fornia, Los Angeles. -. AND I. R. KAPLAN. 1975. Isotopic fractionation of dissolved nitrate during denitrification in the eastern tropical North Pa- cific. Mar. Chem. 3: 271-299. CODISPOTI, L. A., AND J. P....-K. 1979. Geochemistry of inorganic nitrogen compounds in two marine environments: The Santa Barbara basin and the ocean off Peru. Ph.D. Thesis, Univ. of California, Los Angeles. -, AND I. R. KAPLAN. 1989. The eastern tropical Pacific as a source of 15N...

Effect of gamma radiation on the nitrogen metabolism of Paecilomyces Violacea

International Nuclear Information System (INIS)

Salama, A.H.; Nadia, M.; Elzawahry, Y.A.; Abo Elkhair, I.A.

1989-01-01

Quantitative variabilities could be noticed in the nitrogen utilization and mycelial content of mats arising from gamma irradiated and non-irradiated Inocula of P.Violacea. The two lowest doses, 0.1 and 0.25 KGy, showed an increase in nitrate uptake and nitrogen utilization more than control by 7.43 and 15.61% for nitrate uptake and 8.33 and 14.89 for nitrogen utilization respectively, while the higher doses (0.5 up to 3.0 KGy) were inhibitory to the above parameters and also to protein synthesis. The chemical changes in the composition of fungal mats reveal that the peptide-N was the highest in amount as compared with the other nitrogen fractions. The protein-N was second in rank of quantity followed by the amino-N, while the nitrate-N was the least in amount compared to other nitrogen fractions at all radiation treatments

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

Science.gov (United States)

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