• Journal of Korean Society for Atmospheric Environment
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• v.1 no.1
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• pp.99-107
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• 1985

A coated wire ion selective electrode for nitrate (nitrate-CWE_ was constructed using epoxy resin, ion exchanger and plasticizer as a polymer membrane. It's stility, the composition of a polymer membrane, the response characteristics, the selectivity were examined and applied to the environmental analysis. The nitrate-CWE was prepared using a copper wire, wihch was coated with epoxy resin being incorporated with the nitrate ion exchanger and plasticizer. The best composition of the polymer membrane for the nitrate-CWE was obtained by mixing epoxy resin, ion exchanger and plasticizer in the ratio of 2:1:0.4. The potential (56.3$\pm$0.5 mV) of stick form nitrate-CWE in this composition was close to that (59.2 mV) of Nernstian response. The detection limit for nitrate ion were found to the about $6 \times 10^{-5}M$ and the useful pH was 2.5 $\sim$ 10.3. Furthermore, the selectivity of iodide and perchrorate for the nitrage-CWE was also much improved compared with that for a liquid membrane nitrate electrode. The nitrate-CWE was used to determind $NO_x$ in stack gas. The results were in good agreement with those obtained either by electrode method or by the improved NEDA method within a relative error of 4.0%.

• Journal of The Korean Society of Grassland and Forage Science
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• v.20 no.2
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• pp.77-84
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• 2000

Eight-week old perennial ryegrass (Lolium perenne L. cv. Reveille) plants were exposed to different NO3-concentrations or osmotic stress with NaCI. Previously labeled "N was chased during 14 days of non-labeled'NO3 feeding in order to investigate NO3 metabolism in relation to osmoregulation. The short termmeasurement of osmotic potential showed that the extemal concentration of Nos- had not great effect on theosmotic potential, but that osmotic adjustment was observed in NaCl-treated plants. Total uptake of NO 3 - waslargely increased by increasing supply level of NO3 while it was depressed by exposing to osmotic stress.Nitrate reduction increased to more than 29% by increasing extemal NO,- concentration from 1 mM to 10mM. When osmotically stressed with NaCI, nitrate reduction was depressed to about 37% as compared to thecontrol. The decrease in translocation of reduced N into leaves was also observed in NaCl exposed plants. Inthe medium exposed to 10 mM NO,., osmotic contribution of nitrate to cumulative osmotic potential wasdecreased, and it was osmotically compensated with soluble carbohydrate. When osmotically stressed withNaC1, the contribution of chloride was much higher than that of nitrate. The present data indicate that N03-in plant tissues, factually affected by the assimilation of this ion, plays an active role in osmotic regulation incorrelation with other osmotica such carbohydrate and chloride.(Key words : Nitrate metabolism, Osmotic stress, Nitrate supply level, Osmoregulation)ate supply level, Osmoregulation)

• Journal of Plant Biology
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• v.34 no.4
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• pp.283-288
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• 1991

This work was carried out to determined the effect of 2,4-dinitrophenol(DNP) on in vivo nitrate reductase activity in the root of 6 day old rye (Secale cereale L.) seedlings. The nitrate reductase activity in the roots of 6 day old rye seedlings pretreated with 0.5 mM DNP was higher than that of the control group in all the experimental conditions. The optimal concentration of KNO3 for maximum nitrate reductase activity was 10 mM in both control and treated group. The nitrate reductase activity in the treatment of 10 mM KNO3 gradually increased for 4 h in both groups, and then maintained constantly. The nitrate reductase activity occurred per hour was highest at 1 h in both groups, while it was declined by large degrees as time goes on. The daily pattern of nitrate reductase activity was gradually decreased in both groups with the passage of day. The optimal pH for this experiment and a previous paper (Kwon et al., 1991), it was determined that the nitrate reductase activity in both roots and shoots of rye seedlings was increased by the treatment of 0.5 mM DNP, and particulary in both groups, the nitrate reductase activity in the roots of rye seedlings was higher than that in shoots of them.

• Journal of The Korean Society of Grassland and Forage Science
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• v.7 no.3
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• pp.146-152
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• 1987

Sorghum cv. Pioneer 93 1, sorghum-sudangrass hybrid cv. Sioux and maize plant cv. Blizzard were assayed for toxic concentrations of nitrate-nitrogen ($NO_3$-N) and their relationship to morphological characteristics and environmental temperature in a field and phytotron trial. In the phytotron, sorghum and maize plants ranging from emergence to heading stage, were grown under different day/night temperatures of 30125, 25/20,28/18 and 1818 degree C. Nitrate-nitrogen in sorghum and maize plants was accumulated mainly in stems. Therefore nitrate concentration in the young plants was increased as development of stalks advanced and was highest at the stage of 3-4 leaves, when the plants had a leaf weight ratio 0.78-0.80 g/g plant weight. However, nitrate concentrations of the plant decreased as morphological development progressed, especially from the stage of growing point differentiation. Correlation coefficients showed a positive correlation of nitrate concentration with leaf weight ratio, leaf area ratio and specific leaf area, while plant height, dry matter percentage and absolute growth rate showed a negative association with TEX>$NO_3$-N ($P{\le}0.1$%). Cyanogenic glycosides, total nitrogen and crude protein were close associated with nitrate accumulation, and positively significant ($P{\le}0.1$%). High temperature over 30/25^{\circ}C.$ for 3 weeks increased N-uptake and dry matter accumulation, but reduced nitrate concentration. Under cold temperature below 18/8^{\circ}C.$ concentration of nitrate-N was increased in spite of its limited nitrogen uptake and plant growth.

• Membrane and Water Treatment
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• v.10 no.4
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• pp.313-320
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• 2019

Increasing the concentration of nitrate ions in the soil solution and then leaching it to underground aquifers increases the concentration of nitrate in the water, and can cause many health and ecological problems. This study was conducted to evaluate the vulnerability of Meymeh aquifer to nitrate pollution. In this research, sampling of 10 wells was performed according to standard sampling principles and analyzed in the laboratory by spectrophotometric method, then; the nitrate concentration zonation map was drawn by using intermediate models. In the drastic model, the effective parameters for assessing the vulnerability of groundwater aquifers, including the depth of ground water, pure feeding, aquifer environment, soil type, topography slope, non-saturated area and hydraulic conductivity. Which were prepared in the form of seven layers in the ARC GIS software, and by weighting and ranking and integrating these seven layers, the final map of groundwater vulnerability to contamination was prepared. Drastic index estimated for the region between 75-128. For verification of the model, nitrate concentration data in groundwater of the region were used, which showed a relative correlation between the concentration of nitrate and the prepared version of the model. A combination of two vulnerability map and nitrate concentration zonation was provided a qualitative aquifer classification map. According to this map, most of the study areas are within safe and low risk, and only a small portion of the Meymeh Aquifer, which has a nitrate concentration of more than 50 mg / L in groundwater, is classified in a hazardous area.

• Journal of Korean Society for Atmospheric Environment
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• v.2 no.1
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• pp.33-39
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• 1986

Particulate matter was collected by Andersen Air Sampler in the Seoul area during February-October, 1985, in order to investigate size distribution of sulfate and nitrate in aerosol, and conversion of sulfur dioxide to sulfate and that of nitrogen dioxide to nitrate. The size distribution of sulfate and nitrate had fine mode. The ratio of fine sulfate to total sulfate in aerosol and that of fine nitrate to total nitrate showed between 54.6% and 86%, and 55.7% and 95%, respectively, which presumably originated from gaseous reaction of sulfur dioxide and nitrogen dioxide in the atmosphere.

• Journal of Biosystems Engineering
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• v.37 no.3
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• pp.209-213
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• 2012

Purpose: This study was performed to develop a simple, disposable thin-film optical nitrate sensor. Methods: The sensor was fabricated by applying a nitrate-selective polymer membrane on the surface of a thin polyester film. The membrane was composed of polyvinylchloride (PVC), plasticizer, fluorescent dye, and nitrate-selective ionophore. Fluorescence intensity of the sensor increased on contact with a nitrate solution. The fluorescence response of the optical nitrate sensor was measured with a commercial fluorospectrometer. Results: The optical sensor exhibited linear response over four concentration decades. Conclusions: Nitrate ion concentrations in plant nutrient solutions can be determined by direct optical measurements without any conditioning before measurements.

• Journal of Plant Biology
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• v.31 no.3
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• pp.187-196
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• 1988

Chlorella ellipsoidea were cultured in "cold" media starvated with the nitrate and phsophate sources. The effects of the nitrate and phsophate starvation on the biosynthesis of phospholipid and the composition of fatty acids in chloroplasts isolated from these cells were analyzed. The syntheses of phosphatidylcholine and phosphatidylinositol in the nitrate and phosphate starvation were similarly inhibited as compared with the control but phsophatidylethanolamine synthesis in the nitrate starvation was extremely lower than that in the phosphate starvation. The major fatty acids utilized in phospholipid formation within chloroplasts were palmitic acid and linolenic aicd. However, palmitic acid and stearic acid were dominant in the condition of the nitrate starvation. The levels of palmitic acid were enhanced 3-fold than that of the control. These results suggest that the biosynthesis of phospholipid and the composition of fatty acids were affected by the nitrate and phosphate starvation in the culture media.ure media.

• Journal of environmental and Sanitary engineering
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• v.12 no.2
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• pp.75-81
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• 1997

The study was investigated with denitrification of wastewater containing nitrate using upflow anaerobic sludge blanket process. Contents of this study were the determination of nitrate removal efficiency by various hydrogen donor addition, relationship between HRT, nitrate loading rate and growth constant of microorganism in case or various hydrogen donor addition etc. Results from this study were summurized as follows. In case of adding methanol, ethanol, sodium acetate as hydrogen donor, treatability of wastewater contained 200mg/l as nitrate was about 91%. But in addition of ethanol, sodium acetate in wastewater contained 40mg/l as nitrate, nitrate removal efficiency was 80%. While the treatment of nitrate showed the yield coefficient of microorganisms(Y) as 234.8, 234.35, and 247.68 g/VSS/g nitrate, respectively, showed specific growth rate(K) as 0.885, 0.934 and 0.917 respectively.

• YAKHAK HOEJI
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• v.30 no.1
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• pp.8-13
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• 1986

It has been assumed that nitrite, one of the precursor of N-nitrosamine, in human saliva must have been formed from salivary nitrate through the action of microorganism in the oral cavity. In this paper, we have tested the concentration of nitrite and nitrate in human saliva and the degrees of nitrate reduction by oral microflora and identified some bacteria which were able to reduce nitrate. The concentration of nitrite and nitrate was 1.7~9.5ppm and 9.0~28.5ppm respectively. The numbers of total bacteria and nitrate reducing bacteria in four korean human saliva sample were 15~63${\times}10^8$ CFU and 1.0~6.0${\times}10^8$ CFU and the main nitrate reducing bacteria were Streptococcus uberis which was presented in large quantities and showed remarkable reductive activity. Lastly, we knowed that N-dimethylnitrosamine was formed by the reaction between dimethylamine and nitrite in the presence of St. uberis in vitro.