Water-soluble Nitrate Research Articles

Impact of jet-fuel on chemical properties of diverse soils

In the SE Smolensk-Moscow upland and in the Baikonur cosmodrome, changes in the chemical properties of diverse soils (Dystric Arenosols, Cambic Calcisols, Fibric Histosols and Albic Luvisols) were studied after the jet-fuel treatments of 1, 5, 10, 25 and 100 g/kg during a one- year pot experiment (one soil per region) and during two-year field experiments (in all soils). Among the controlled soil properties, only organic matter carbon content increased as jet-fuel load increased. For the other soil properties namely moisture, pH value, the concentration of available phosphorus and potassium, exchangeable ammonium, water-soluble nitrate, the total content of carbon and nitrogen, there were no obvious trends, which reflects a rather high stability of these soil properties to jet-fuel contamination in loads up to 100 g/kg.

EFFECT OF THE FORM OF ELECTRIC DISCHARGE ON PHYSICOCHEMICAL PROPERTIES OF PLASMA-ACTIVATED DISTILLED AND GROUND WATERS

A comparative study of some physicochemical properties of aqueous solutions resulted from the treatment of distilled and ground waters by pulsed discharges has been performed. Changes in the pH value, the conductivity of the solution, and the content of NO3¯ anions and Ca++, Mg++, K+, and Na+ cations were studied. Water bodies were affected by active particles formed in the air under the action of a pulsed discharge, which is implemented in two options. The first option is conventionally called ‘bubble discharge’ since it assumes the ignition of a discharge in an air bubble in direct contact with a liquid. The second option is the case when active particles, which are formed in an air stream under the action of a barrier discharge, are blown into a liquid. It is shown that the bubble discharge in ground water gives the maximum performance for the NO3¯ anions, while in the case of barrier discharge the best performance in the formation of NO3¯ anions is observed in distilled water. The pH value for ground water increases from 8.1 to 8.6 in the course of a 10-minute treatment using both discharges. However, in the case of distilled water treatment an inverse relationship is observed, so its value decreases from 7.5 to 3.5 pH. A multiple increase in the content of Ca++ and Mg++ cations in the water sample is observed when groundwater treating. Presumably, their increase in solution is associated with the transition of insoluble salts of calcium and magnesium carbonates (constant water hardness) into water-soluble nitrates (temporary hardness). In addition to magnesium and calcium ions, potassium and sodium cations were monitored in water samples. Their concentration in water was insignificantly affected by the treatments with discharges.

Water-soluble nickel and iron salts for hydroxymethylfurfural (HMF) and water oxidation: the simplest precatalysts?

We report on a rapid, green, and cost-effective fabrication of nickel(-iron) oxyhydroxides by drop-coating and reconstructing water-soluble nitrate precursors, and their application for the OER and the oxidation of 5-hydroxymethylfurfural (HMF).

Determination of water-soluble nitrate ions in PM2.5 particles using UiO-67 modified glassy carbon electrode

Determination of water-soluble nitrate ions in PM2.5 particles using UiO-67 modified glassy carbon electrode

Reduction of Water-soluble Nitrate ion in dust Using Alternative Compound Fuels in Fine-dust-reduction Cement Process

Reduction of Water-soluble Nitrate ion in dust Using Alternative Compound Fuels in Fine-dust-reduction Cement Process

Development of Electrospun WE43 Magnesium Alloy-Like Compound.

Metallic structures are conventionally fabricated with high temperature/deformation processes resulting the smallest possible microscopic structures in the order of several hundreds of micrometer. Therefore, to obtain structures with fibers smaller than 100 μm, those are unsuitable. In this study, electrospinning, a fiber fabrication technique commonly used for polymers, was adopted to fabricate a WE43 magnesium alloy-like fibrous structure. The aim is to adopt metallic WE43 alloy to regenerative medicine using tissue engineering approach by mimicking its composition inside of a fibrous structure. The solution required for electrospinning was obtained with water soluble nitrates of elements in WE43 alloy, and PVP or PVA were added to obtain a spinnable viscosity which was pyrolised away during heat treatment. Electrospinning parameters were optimized with naked-eye observations and SEM as 1.5 g salts and 5 wt.% PVA containing solution prepared at 90 °C and electrospun under 30 kV from a distance of 12-15 cm with a feeding rate of 5 μl/min. Then the samples were subjected to a multi-step heat treatment under argon to remove the polymer and calcinate the nitrates into oxides which was designed based on thermal analyses and reaction kinetics calculations as 6 h at 230 °C, 8.5 h at 390 °C, 5 h at 465 °C, 80 h at 500 °C and 10 h at 505 °C, consecutively. The characterizations conducted in terms of structure, composition and crystallinity with XRD, XPS, EDX and SEM showed that it is possible to obtain MgaYbNdcZrdOx (empirical) fibers with the same composition as WE43 in sub-millimeter sizes using this approach.

Stable Isotopes of Nitrate, Sulfate, and Carbonate in Soils From the Transantarctic Mountains, Antarctica: A Record of Atmospheric Deposition and Chemical Weathering

Soils in ice-free areas in Antarctica are recognized for their high salt concentrations and persistent arid conditions. While previous studies have investigated the distribution of salts and potential sources in the McMurdo Dry Valleys, logistical constraints have limited our investigation and understanding of salt dynamics within the Transantarctic Mountains. We focused on the Shackleton Glacier (85° S, 176° W), a major outlet glacier of the East Antarctic Ice Sheet located in the Central Transantarctic Mountains (CTAM), and collected surface soil samples from 10 ice-free areas. Concentrations of water-soluble nitrate (NO3¬-) and sulfate (SO42-) ranged from <0.2 to ~150 µmol g-1 and <0.02 to ~450 µmol g-1, respectively. In general, salt concentrations increased with distance inland and with elevation. However, concentrations also increased with distance from current glacial ice position. To understand the source and formation of these salts, we measured the stable isotopes of dissolved NO3- and SO42-, and soil carbonate (HCO3- + CO32-). δ15N-NO3 values ranged from -47.8 to 20.4‰ and, while all δ17O-NO3 values are positive, they ranged from 15.7 to 45.9‰. δ34S-SO4 and δ18O-SO4 values ranged from 12.5 and 17.9‰ and -14.5 to -7.1‰, respectively. Total inorganic carbon isotopes in total bulk soil samples ranged from 0.2 to 8.5‰ for δ13C and -38.8 to -9.6‰ for δ18O. A simple mixing model indicates that NO3- is primarily derived from the troposphere (0-70%) and stratosphere (30-100%). SO42- is primarily derived from secondary atmospheric sulfate (SAS) by the oxidation of reduced sulfur gases and compounds in the atmosphere by H2O2, carbonyl sulfide (COS), and ozone. Calcite and perhaps nahcolite (NaHCO3) are formed through both slow and rapid freezing and/or the evaporation/sublimation of HCO3 + CO3-rich fluids. Our results indicate that origins of salts from ice-free areas within the CTAM represent a complex interplay of atmospheric deposition, chemical weathering, and post-depositional processes related to glacial history and persistent arid conditions. These findings have important implications for the use of these salts in deciphering past climate and atmospheric conditions, biological habitat suitability, glacial history, and can possibly aid in our future collective understanding of salt dynamics on Mars.

Interaction between Fungal Communities, Soil Properties, and the Survival of Invading E. coli O157:H7 in Soils.

Pathogens that invade into the soil cancontaminate food and water, andinfect animals and human beings. It is well documented that individual bacterial phyla are well correlated with the survival of E. coliO157 (EcO157), while the interaction betweenthe fungal communities and EcO157 survival remains largely unknown. In this study, soil samples from Tongliao, Siping, and Yanji in northeast China were collected and characterized. Total DNA was extracted for fungal and bacterial community characterization. EcO157 cells were spiked into the soils, and their survival behavior was investigated. Results showed that both fungal and bacterial communities were significantly correlated (p < 0.01) with the survival of EcO157 in soils, and the relative abundances of fungal groups (Dothideomycetes and Sordariomycetes) and some bacterial phyla (Acidobacteria, Firmicutes, gamma- and delta-Proteobacteria)weresignificantly correlated with ttds (p < 0.01). Soil pH, EC (electric conductance) salinity, and water-soluble nitrate nitrogen were significantly correlated with survival time (time to reach the detection limit, ttd) (p < 0.05). The structural equation model indicated that fungal communities could directly influence ttds, and soil properties could indirectly influence the ttds through fungal communities. The first log reduction time (δ) was mainly correlated with soil properties, while the shape parameter (p) was largely correlated with fungal communities. Our data indicated that both fungal and bacterial communities were closely correlated (p < 0.05)with the survival of EcO157 in soils, and different fungal and bacterial groups might play different roles. Fungal communities and bacterial communities explained 5.87% and 17.32% of the overall variation of survival parameters, respectively. Soil properties explained about one-third of the overall variation of survival parameters. These findings expand our current understanding of the environmental behavior of human pathogens in soils.

Designing Novel Multiferroic Perovskite Oxide for Prospective Photovoltaic Applications

Multiferroics, with two or more coexisting ferroic orders (ferroelectric, ferro (antiferro)-magnetic) in a single phase, display promising photovoltaic characteristics which can be utilised in solar energy harvesting. However, the efficacy is seriously challenged due to their wide band gap, far from the ideal value of ~1.52 eV for photovoltaic applications, resulting in overall unimpressive performance. In the present work, an approach towards imparting multiferroism in an otherwise non-ferroic system was adopted through strain engineering. Bulk SrMnO3 (SMO) is antiferromagnetic-paraelectric. However, our previous first-principles studies predicted high-pressure phase transformation from bulk non-polar phase to a tetragonal polar phase. In light of the above, SMO was synthesised hydrothermally at 200°C for 96 h using water-soluble nitrate salts of strontium and manganese. FESEM study reveals the formation of hexagonal bipyramid shaped SMO crystals with elongated 1-D features. Powder x-ray diffraction studies and subsequent Rietveld refinement confirm the presence of hexagonal (P63/mmc) as well as tetragonal (P4mm) phases. Energy dispersive x-ray analysis (EDAX) confirms Sr/Mn ≈ 1, the stoichiometric ratio. UV-VIS spectroscopy was utilised to estimate the optical bandgap of the as-grown sample which was found to be in the range of 1.4-1.5 eV. Temperature-dependent magnetisation plot indicates the magnetic transition temperature, ~275K.

Signaling pathways underlying nitrogen-dependent changes in root system architecture: from model to crop species.

Among all essential mineral elements, nitrogen (N) is required in the largest amounts and thus is often a limiting factor for plant growth. N is taken up by plant roots in the form of water-soluble nitrate, ammonium, and, depending on abundance, low-molecular weight organic N. In soils, the availability and composition of these N forms can vary over space and time, which exposes roots to various local N signals that regulate root system architecture in combination with systemic signals reflecting the N nutritional status of the shoot. Uncovering the molecular mechanisms underlying N-dependent signaling provides great potential to optimize root system architecture for the sake of higher N uptake efficiency in crop breeding. In this review, we summarize prominent signaling mechanisms and their underlying molecular players that derive from external N forms or the internal N nutritional status and modulate root development including root hair formation and gravitropism. We also compare the current state of knowledge of these pathways between Arabidopsis and graminaceous plant species.

Influence of alkali hydroxides on synthesis, physico-chemical and photoluminescence properties of zinc oxide nanoparticles

ZnO nanoparticles (NPs) have been synthesised by co-precipitation method using zinc nitrate in the presence of two different alkali hydroxides. The XRD analysis of as-prepared products, before and after washing demonstrates its importance in removal of the water soluble nitrates of alkali metals formed during co-precipitation. The X-ray diffraction patterns of the synthesised ZnO NPs confirm the formation of ZnO with hexagonal wurtzite phase. The ZnO NPs synthesised, as confirmed by the XRD pattern, in the presence of NaOH show comparatively smaller crystallite size. These quasi-spherical ZnO NPs show strong UV absorption and dominant visible PL emission, suitable for biomedical and photocatalytic applications.

Structural and Electrochemical Study on Thin Film Cathodes Fabricated By Spray Pyrolysis

Cathode ORR is the most complicated process in solid oxide fuel cells (SOFC), since it involves oxygen molecule adsorption and dissociation, electron transfer and oxygen ion transport. Most of the cathodes used in SOFC contain mixed ionic electronic conducting (MIEC) oxides [1]. Either they are used as single phase, if the material exhibits sufficient ionic conductivity in addition to electronic conductivity, or as a composite with an oxygen ion conductor such as yttria-stabilized zirconia (YSZ) or rare earth oxide doped ceria. It is well known that microstructure plays a crucial role in determining the polarization resistance [2,3]. Typically, the finer the cathode microstructure, the lower is the polarization resistance [2,3]. We have recently reported on the deposition of cathodes from an aqueous solution directly on electrolyte surfaces by spray-pyrolysis followed by thermal treatment at 700oC [4]. In this work, we have investigated cathode polarization resistance of many cathodes prepared by the spray pyrolysis process. This would then allow one to determine similarities and differences across many cathodes prepared by a single process. A total of eight different cathodes containing transition metal ions were selected for this study. Two types of cathodes were synthesized: Single phase MIEC, and MIEC with gadolinia-doped ceria (GDC) composite cathodes. These were: La0.6Sr0.4CoO3-x (LSC), La0.6Sr0.4Co0.2Fe0.8O3-x (LSCF), LaNi0.6Fe0.4O3-x (LNF), PrNi0.6Co0.4O3-x (PNC), Sm0.5Sr0.5CoO3-x (SSC), Ba0.5Sr0.5Co0.8Fe0.2O3-x (BSCF), Pr0.6Sr0.4Co0.8Fe0.2O3-x (PSCF), and PrBa0.5Sr0.5Co1.5Fe0.5O5+y (PBSCF). Water soluble nitrates of the respective elements were used. Thin films of about 100 nm were spray-coated onto 1mm thick 8YSZ discs to fabricate symmetric cells for EIS measurement. Thick films of about 1 um were spray-coated for XRD and EDS measurement. Cathode particle size was calculated from XRD peak widening using Scherrer formula. The particle sizes of all sixteen cathodes were plotted in figure 1. All composite cathodes have smaller particle size than their corresponding single phase cathodes. This was caused by diffusion blocking during co-sintering of composite cathodes. Cathode composition was characterized by EDS. Stoichiometry of these cathodes were very close to target value. Electrochemical impedance spectroscopy was measured over a temperature range between 400oC and 700oC. Figure 2(a) shows the Arrhenius plots of the polarization resistance over a temperature range from 400oC to 700oC for all eight single phase cathodes. Figure 2(b) shows the Arrhenius plots of the polarization resistance of all composite cathodes. As seen in the figures, all plots are linear consistent with Arrhenius behavior over the temperature range. Also, all lines are nearly parallel to each other, indicating essentially the same activation energy. The measured activation energy ranged between ~1.14 eV and ~1.35 eV. The polarization resistance for composite cathodes is given by [2] (1) Therefore, the thermal activation part is contributed by charge transfer resistance and ionic resistance. As a result, the activation energy can be expressed by (2) While, the polarization resistance for single phase cathodes is given by [3] (3) Therefore, the thermal activation part is contributed by oxygen diffusion and surface exchange reaction. As a result, the activation energy can be expressed by (4) Activation energy of the polarization resistance is similar for these materials, which is reasonable as all of them contain one or more transition metals, Co, Fe and Ni. The large difference in polarization resistance is attributed to the pre-exponential factor. One of the factors in the pre-exponential part is the geometrical part. Possible differences in porosity, agglomeration, degree of mixing (uniformity) of the two phases in composite electrodes, may substantially alter the pre-exponential part. Acknowledgements: This work was supported by the National Science Foundation under grant Number NSF-CBET-1604008 and by the US Department of Energy under grant Number DE-FG02-06ER46086.

Non-linear hydraulic properties of woodchips necessary to design denitrification beds

Denitrification beds are being used to reduce the transport of water-soluble nitrate via subsurface drainage systems to surface water. Only recently has the non-linearity of water flow through woodchips been ascertained. To successfully design and model denitrification beds with optimum nitrate removal, a better understanding of flow in denitrification beds is needed. The main objectives of this study were to characterize the hydraulic properties of old degraded woodchips and provide a better understanding of the factors affecting flow. To achieve this goal, we conducted constant-head column experiments using old woodchips that were excavated from a four-year old denitrification bed near Willmar, Minnesota, USA. For Izbash’s equation, the non-Darcy exponent (n) ranged from 0.76 to 0.87 that indicates post-linear regime, and the permeability coefficient (M10) at 10°C ranged from 0.9 to 2.6cms−1. For Forchheimer’s equation, the intrinsic permeability of 5.6×10−5cm2 and ω constant of 0.40 (at drainable porosity of 0.41) closely resembled the in-situ properties found in a previous study. Forchheimer’s equation was better than that of Izbash’s for describing water flow through old woodchips, and the coefficients of the former provided stronger correlations with drainable porosity. The strong correlation between intrinsic permeability and drainable porosity showed that woodchip compaction is an important factor affecting water flow through woodchips. Furthermore, we demonstrated the importance of temperature effects on woodchip hydraulics. In conclusion, the hydraulic properties of old woodchips should be characterized using a non-Darcy equation to help design efficient systems with optimum nitrate removal.

Isotopic composition of water-soluble nitrate in bulk atmospheric deposition at Dongsha Island: sources and implications of external N supply to the northern South China Sea

Abstract. Increased reactive nitrogen (Nr, NO3− &amp;amp;plus; NH4&amp;amp;plus;+ &amp;amp;plus; dissolved organic nitrogen) emission from the Asian continent poses profound threats to ecosystem safety from terrestrial throughout the ocean proper. To quantify atmospheric Nr input, diagnose its sources, and evaluate influence on marine nitrogen cycle of the South China Sea (SCS), an oligotrophic marginal sea adjacent to the emission hot spot China, we conducted measurements of concentrations of nitrate and ammonium as well as other major ions and dual isotopes of nitrate (δ15NNO3 and δ18ONO3) in atmospheric deposition collected from Dongsha Island off southern China. The δ15NNO3 and δ18ONO3 for dry deposition averaged at −2.8‰ and +58.8‰, ranging from −7.5 to +3.7‰ and from ∼ +17 to +88‰, respectively. Wet deposition, although with limited samples, showed a similar flux-weighted mean in δ15NNO3 (−2.6‰) yet a significantly higher mean in δ18ONO3 (+78.8‰). The dual isotope ratios showed an anti-correlation and an inverse seasonality; the δ15NNO3 values were higher in summer compared to those in winter, while the δ18ONO3 values were higher in winter than those in summer. In winter, not only dual isotopic compositions of nitrate but also the ammonium and nitrate dry deposition fluxes were relatively uniform, demonstrating a persistent influence of fossil fuel combustion sourced from Asian continental outflows via the northeasterly monsoon winds. More variable isotopic values in summer likely suggest varying sources and dynamical formation processes of dry deposition nitrate. Biomass burning and lightning are suggested to be responsible for the observed higher δ15NNO3 values in summer. Atmospheric nitrate and ammonium deposition together was estimated to be ∼50 mmol N m−2 year−1, with the dominance of nitrate in dry deposition but ammonium slightly higher in wet deposition. If not including this additional fertilization of atmospheric inorganic nitrogen deposition to enhance the carbon sequestration, CO2 release out of the SCS would be double than that of the present amount, 460 ± 430 mmol C m−2 year−1. Our study demonstrates that atmospheric deposition may serve as an important external Nr supplier to the SCS; however it is difficult to separate the isotopic signal from N2 fixation (−2–0‰) due to their similarity in δ15NNO3. More studies related to isotopic composition of nitrogen speciation in atmospheric Nr deposition, their relative contributions and source identification, and the role of typhoons in the SCS are required.

Nitrogen and oxygen isotopic compositions of water-soluble nitrate in Taihu Lake water system, China: implication for nitrate sources and biogeochemical process

The stable isotope nitrogen-15 (15N) is a robust indicator of nitrogen (N) source, and the joint use of δ15N and δ18O–NO3 − values can provide more useful information about nitrate source discrimination and N cycle process. The δ15N and δ18O–NO3 − values, as well as major ion tracers, from Taihu Lake in east China were investigated to identify the primary nitrate sources and assess nitrate biogeochemical process in the present study. The results show that the nitrate concentration in West Taihu Lake (WTL) was generally higher than those in East Taihu Lake (ETL) and its upstream inflow rivers. The NO3 −/Cl− value combined with mapping of δ15N–NO3 − and NO3 − concentration suggest that the mixing process should play a major effect in WTL, and denitrification was the dominant N transformation process in WTL. A linear relationship of close to ~1: 2 was observed between δ15N–NO3 − and δ18O–NO3 − values in WTL, confirming the occurrence of denitrification in WTL. The δ15N–NO3 − data imply that sewage and manure were the principal nitrate sources in WTL and its feeder rivers, while the nitrate in ETL might derive from soil organic nitrogen and atmospheric deposition. The δ18O–NO3 − data indicate most of nitrate from microbial nitrification of organic nitrogen matter possibly make a significant contribution to the lake.

Studies of Inorganic Anions at Different Depth of Agriculture Soil and its correlation with Ground Water Pollution

The present research study has been conducted in the vicinity of industrial city, Kota in Rajasthan where six agriculture fields ,two each of paddy, soyabean and wheat crops were selected for analysis work.. Chemical fertilizers applied in these fields were mainly urea, diammonium phosphate, zinc sulphate and potassium chloride. Soil samples have been collected from every field at various depths prior to and after the crop as well as during the crop growth pH, E.Ce. and water soluble Nitrate (NO3 - ), Chloride (Cl - ), Sulphate (SO4 2- ) and Phosphate (PO4 3- ) were estimated in all collected samples. An effort has been made to find the change in soil characteristic of the field before and after the crop. Ground water quality of rural areas of four major district that is Kota, Baran, Bundi and Jhalawar of Hadoti region of Rajasthan were also assessed to find out correlation between leaching of anions and water pollution.

Aerosol Inorganic Composition at a Tropical Site: Discrepancies Between Filter-Based Sampling and a Semi-Continuous Method

The concentrations of the water-soluble inorganic aerosol species, ammonium (NH4 +), nitrate (NO3 −), chloride (Cl−), and sulfate (SO4 2−), were measured from September to November 2002 at a pasture site in the Amazon Basin (Rondonia, Brazil) (LBA-SMOCC). Measurements were conducted using a semi-continuous technique (Wet-annular denuder/Steam-Jet Aerosol Collector: WAD/SJAC) and three integrating filter-based methods, namely (1) a denuder-filter pack (DFP: Teflon and impregnated Whatman filters), (2) a stacked-filter unit (SFU: polycarbonate filters), and (3) a High Volume dichotomous sampler (HiVol: quartz fiber filters). Measurements covered the late dry season (biomass burning), a transition period, and the onset of the wet season (clean conditions). Analyses of the particles collected on filters were performed using ion chromatography (IC) and Particle-Induced X-ray Emission spectrometry (PIXE). Season-dependent discrepancies were observed between the WAD/SJAC system and the filter-based samplers. Dur...

Soil properties and processes driving the leaching of nitrate in the forested catchments of the eastern escarpment of South Africa

Elevated levels of nitrate in streamwaters draining forested catchments in the eastern escarpment area of South Africa are thought to occur as a result of land use change from natural high altitude grasslands to plantation forestry. In this investigation, soil samples taken from similar pedosystems in adjacent (about 50 m from each other) forest and grassland ecosystems were tested for a range of properties in order to determine differences, which might indicate the reasons for elevated leaching of nitrate from forest soils in these areas. Soils were collected monthly in the summer season and analysed for pH, total nitrogen, total phosphorus, organic carbon and net nitrogen mineralisation rates. From the soils collected with depth (10 cm intervals), a saturated paste extract was prepared from which the major anions, cations, electrical conductivity, pH and the nitrate sorption were analysed. Three parent rock types were studied namely dolomite, mixed dolomite and quartzite and quartzite. Soil pH reduction of as much as 0.51 units was found, with the median pH of 4.30 and 4.07 for grassland and forest soils, respectively. There was a high level of soil organic matter in soils of dolomitic origin, followed by those of mixed dolomitic and quartzitic origin and finally by those of quartzitic origin. The general trend with respect to the changes in the total nitrogen, total phosphorus and the C:N ratio ( P < 0.01) followed the trends shown by the soil organic carbon. The net rates of nitrogen mineralisation pointed significantly towards more rapid nitrogen mineralisation and nitrification rates in forest soils (average 0.9 μg N g soil −1 day −1) than those under the adjacent grassland sites (average 0.3 μg N g soil −1 day −1). This was more noticeable in the more clayey, dolomitic-derived soil at the beginning of the study period in September 2000. The concentration of water-soluble nitrate in the topsoil horizons in grassland soils was low (less than 0.2 mmol l −1) compared to that of the forest soils (up to 1.1 mmol l −1). The clearest nitrate sorption trends were provided from the graph representing the lowest level of nitrate addition (3.4 mmol/kg) in grassland soils. The results of this study suggest that afforestation has changed the capacity of the soils to retain nitrate. Nitrate leaching into streamwaters may impact on other land use activities in the lower reaches of the catchment.

Characterization of red beet and carrot with special emphasis on nitrate accumulation

Nitrate accumulation in plants is a natural phenomenon resulting from uptake of nitrate ion in excess of its reduction and subsequent assimilation. The water soluble nitrate content of various carrot and red beet varieties was measured as a function of irrigation and mineral supplement in three years. In the first year, the nitrate content increased in both roots (significant differences were found for three carrot and at three red beet cultivars) following the irrigation. The activity of nitrate-reductase in the leaves was also significantly higher after irrigation in three red beet varieties in 1998. The mineral supplement in most of the carrot varieties increased the nitrate content. In the third year, the impact of water supply showed various tendencies in nitrate accumulation in both vegetables. On the basis of results for three years, the conclusion was that the seasonal and varietal differences were also remarkable.

Nitrogen Release Rate Differs by Fertilizer Source

Abstract Controlled-release fertilizers allow growers to reduce leachate nitrogen loss and better manage crop nutrition in comparison to water-soluble fertilizers. Nitrogen leaching and plant growth were evaluated in a container production system using a granular water-soluble (GWS) ammonium nitrate fertilizer (34-0-0), a controlled-release fertilizer (CRF) (18N-6P-12K), and a non-fertilized control (NFC). Selected plant species were grown for ten weeks using 1,485 g N per cubic meter (2.5 pounds N per cubic yard) CRF or the GWS fertilizer. Leachate pH was higher (7.0+) for the GWS and NFC treatments than the CRF (6.5 to 7.0). Total soluble salts in the leachates reflected the initial leaching of salts from the substrate, with a continued decrease in soluble salts for the GWS fertilizer and NFC treatments. With the CRF, soluble salts decreased slightly during the first five weeks, but then increased over the next five weeks. The CRF provided acceptable ammonium levels for production purposes throughout th...