• Korean Journal of Food Science and Technology
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• v.23 no.2
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• pp.133-140
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• 1991

Weight-loss, general-appearante, yellowing, and compositions such as chlorophyll, carotenoid, vitamin C and nitrate, were studied to investigate the influence of pre-(cultivar and growing season) and post-(low-temperature and high-density polyethylene film packaging) harvest factors on the shelf-life and quality of leaf lettuce(Lactuca sativa L). Weight-loss was reduced by the treatment of high-density polyethylene film packaging, and more at $0{\sim}1^{\circ}C$ than $4{\sim}5^{\circ}C$. Leaf-lettuce grown in Winter lost less fresh weight than that grown in Autumn. In experiment on difference between cultivars, the reduction of weight-loss in 'Cheongchima' lettuce was somewhat significant than that in 'Jeokchukmyeon' lettuce. The tendency of changes in general appearance was similar to that of weight-loss. The yellowing of leaf lettuce during the storage was caused by chlorophyll degradation. Vitamin C content before the storage was 128.0 mg/100 g FW. in lettuce grown in Winter, 123.8 mg/100g FW. in that grown in Autumn, and more 'Cheongchima' lettuce than 'Jeokchukmyeon' lettuce. In all treatment, vitamin C content decreased rapidly, and this tendency was more obvious at $4{\sim}5^{\circ}C$ than $0{\sim}1^{\circ}C$. The nitrate content of 'Jeokchukmyeon' was 3812.6 ppm and that of 'Cheongchima' was 2855.6 ppm before the storage. Nitrate content decreased more at $4{\sim}5^{\circ}C$ than $0{\sim}1^{\circ}C$ during the storage.

• Korean Journal of Soil Science and Fertilizer
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• v.41 no.3
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• pp.164-169
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• 2008

This experiment was carried out to find the growth response and changes of nitrate and soluble sugar content in tomato leaves with salt stress. Tomato (Solanum lycopericum) seedlings were grown under different electrical conductivity (EC) levels adjusted with $CaCl_2$ as 1, 2, and $6dS\;m^{-1}$. The growth response and contents of nitrate and soluble sugar in tomato plants were examined at 7 and 14 days after salt treatment. Leaf area and dry weight ratio of shoot to root of tomato plants were decreased as EC level increased. Photosynthetic rate of leaves was reduced under high EC level due to the stomatal closure and the reduction of transpiration rate. The soluble sugar and starch content were lower in the tomato leaves grown under high EC level. Total nitrogen and nitrate contents were decreased in high EC level, whereas the ammonium content was increased. High-salt stress induced the accumulation of salt crystal in mesophyll cells of tomato leaf.

• Journal of Bio-Environment Control
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• v.17 no.1
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• pp.43-50
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• 2008

This study was conducted to investigate the proper supplied conditions of sodium selenate supplied by fertigation to improve functionality of major western vegetables; beet, broccoli, cabbage lettuce, celery, and parsley in highland. In this work, the growth and content of minerals, ascorbic acid, nitrate, and selenium were measured in western vegetables that treated sodium selenate by different concentration, treatment time and treatment frequency. While there was not different in early growth of some western vegetables among different concentration of sodium selenate; 1,2, 5 and $20\;mg{\cdot}L^{-1}$, at 20 days after treatment, the fresh weight was reduced 33% at cabbage lettuce,47% at broccoli, and 74% at parsley compared control in $5\;mg{\cdot}L^{-1}$ treatment. But the fresh weight of beet and celery reduced just 20% and 15% compared control in even $20\;mg{\cdot}L^{-1}$. The ascorbic acid of cabbage lettuce, celery, and beet increased as sodium selenate concentration increased, so that of cabbage lettuce showed 1.2 times compared control in $20\;mg{\cdot}L^{-1}$ treatment and also that of beet and celery increased 10%. But the ascorbic acid of broccoli and parsley was not influenced by treated sodium selenate. As the concentration of sodium selenate increased, the nitrate contents decreased regardless of crops compared control. This reduced effect of nitrate was highest in cabbage lettuce, followed by beet and celery. The mineral contents, such as K, Ca, and Mg, decreased in all crops, as the concentration of sodium selenate increased. The potassium content showed an obvious negative correlationship with the concentrations of sodium selenate regardless of crops, but the magnesium and calcium content did not show significant difference between treatments. The selenium content increased in proportion as increasing sodium selenate concentrations. The broccoli, celery and parsley treated $20\;mg{\cdot}L^{-1}$ sodium selenate showed 24.4 times, 76.4 times, and 560 times higher than control, respectively. When the sodium selenate supplied to some western vegetables in different growth stage, the selenium content increased 1.3 times and 1.4 times higher in early stage than in late stage in cabbage lettuce and broccoli, respectively. However in parsley and celery, the selenium content showed the highest in middle stage. The selenium content increased in proportion as increasing the sodium selenate treatment frequency, but in above 10 times treatment, the increased effect alleviated in parsley, celery, and cabbage lettuce. On the contrary, the selenium content of broccoli increased constantly as treatment frequency increased.

• Korean Journal of Organic Agriculture
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• v.5 no.1
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• pp.101-110
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• 1996

Inorder to minimize the daily intake amount of nitrate by chinese cabbage, the favorate vegetable for Korean, the influences of storage conditions at different temperature and light or dark treatments after post-harvest and effects of cooking temperature and infrared rays on changes of nitrate contents in edible parts of chinese cabbage were determined. The nitrate contents on midrib and leaf blade in chinese cabbage during post-harvest were decreased steeply in 2 days and decreased slowly again in 5 days. The temperature treatment to decrease the nitrate contents in midrib and leaf blade of chinese cabbage were effective as the following of $25^{\circ}C$> $15^{\circ}C$ > $-4^{\circ}C$ > $-10^{\circ}C$. The nitrate contents of midrib and leaf blade were decreased in the timecourse of post-harvest. It is more effective to store in $4^{\circ}C$ than in $15^{\circ}C$, and is more effective in transparent vinyl package than in black vinyl package, but the treatment of light is more effective than the treatment of temperature. The nitrate contents of midrib decreased rapidly by 17.9% in the treatment of 5 days at$ 15^{\circ}C$. By treatment of $80^{\circ}C$, $90^{\circ}C$, $100^{\circ}C$ water, the nitrate contents of midrib were increased slightly, but decreased in leaf blade. It reached 68.5%, 50.6%, 45.9% in the leaf blade respectively by treatment of 80%, 90%, 100% water at 1 min. By infrared rays treatment, the nitrate contents of midrib did not change in 3 min but increased rapidly after 6 min, and in the leaf blade it increased continually after 1 min.

• Animal Bioscience
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• v.34 no.6
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• pp.1022-1028
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• 2021

Objective: Supplemental nitrate is known to be an effective tool to mitigate methane emission by ruminants. Based on theoretical considerations, supplemental nitrate can improve but also deteriorate the growth performance. The overall effect of supplemental nitrate on growth performance, however, is not yet known. The objective of the current study was therefore to evaluate the effect of a higher dose of NO3- on overall growth performance when feeding either Pangola grass hay or rice straw. Methods: Thirty-two crossbred, 3-month-old Thai native×Anglo-Nubian crossbred male goats were used. The experiment had a 2×2 factorial design with an experimental period of 60 days. Eight goats were randomly allocated to each dietary treatment, i.e. a ration containing either Pangola hay (Digitaria eriantha Steud) or rice straw (Oryza Sativa) as a source of roughage, supplemented with a concentrate containing either 3.2% or 4.8% potassium nitrate. The rations were formulated to be isonitrogenous. The animals were weighed at the start of the experiment and at days 30 and 60. Feces were collected during the last five days of each 30-day period. Results: High-nitrate increased overall DM intake by approximately 3%, irrespective the source of roughage, but only the goats fed a rice straw-based ration responded with an increase in body weight (BW). Thus, the overall feed conversion ratio (kg feed/kg BW gain) was influenced by roughage source ×nitrate and decreased by almost 60% when the goats were fed rice straw in combination with a high versus a low dietary nitrate content. The digestibility of macronutrients was only affected by the source of roughage and the digestibility of organic matter, crude protein, and neutral detergent fibre was greater when the goats were fed Pangola hay. Conclusion: It was concluded that the replacement of soybean meal by nitrate improves the growth performance of meat goats fed rations based on rice straw, but not Pangola hay.

• Korean Journal of Soil Science and Fertilizer
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• v.23 no.1
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• pp.40-43
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• 1990

Study was conducted to investigate the optimum amount of nitrogen fertilizer for the green forage production of Italian ryegrass at the paddy field after rice harvesting in southern part of Korea in 1987 and 1988. Effects of three levels of nitrogen fertilizer application (15, 30 and 45 kg N/10a) on the green yield and nitrate content of green forage at three cutting times (April 30, May 20 and June 10) were examined in 1988. The results were as follows. 1. Yield of green forage at all cutting times increased in order of 45 > 30 > 15 kg N/10a, and it increased about 14 percent in the 45 kg N/10a and decreased about 35 percent in the 15 kg N/10a compared with the 30 kg N/10a. 2. Nitrate content in the green forage at all cutting times was high with increasing amount of nitrogen fertilizer and with decreasing ratio of K/(Ca+Mg) in green forage. The nitrate content at the second and the third cutting times in the 45 kg N/10a might be outrunned the tentative limitation for cattle. 3. Maximum amount of nitrogen fertilizer was 48 kg/10a for total green forage production, but it was 38 kg/10a near at cattle's harmful limit of nitrate content in green forage.

• Ocean and Polar Research
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• v.30 no.1
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• pp.1-10
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• 2008

In order to find the effect of intertidal sediments on nutrient cycle in coastal environment, we measured ammonia, nitrate, phosphate, and silicate concentrations every hour during at least 12 hours in the entrance of Keunso Bay during four seasons. The content of ammonia and silicate do not change considerably with season, but nitrate shows large seasonal variation. In summer, nitrate concentration was much lower than in other seasons, which resulted from large biological uptake and active denitrification in intertidal sediments during summer. Phosphate also exhibit seasonal variations, but not that large like nitrate. N/P and N/Si ratios were lower in summer than in other seasons, which was due to active denitrification in the intertidal sediments during summer. For all seasons, ammonia concentrations were higher at low tide than at high tide, but nitrate concentrations were higher at high tide. Dissolved inorganic nitrogen concentrations measured in spring, summer, and winter were higher at high tide than at low tide, but in fall, they were higher at low tide than at high tide. For spring and winter, phosphate and silicate concentrations were higher at low tide than at high tide, while in summer and fall, they were higher at high tide than at low tide. In Keunso Bay, intertidal sediments affect significantly the nutrient cycle around the coastal areas. The intertidal sediments act as a source for ammonia and silicate, but as a sink for nitrate. However, phosphate is not considerably influenced by intertidal sediments.

• Journal of Nutrition and Health
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• v.15 no.1
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• pp.39-46
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• 1982

Nitrate accumulated in vegetables can, via $NO_2$ during storage and after their ingestion, cause the formation of methemoglobin and many of which are carcinogenic in human body. Especially such vegetables with the highest consumption in Korea as chinese cabbage and raddish frequently showed that high contents of nitrate and nitrite could accumulate. Therefore, pH and the content of nitrate and nitrite of Korean pickles made of upper vegetables, viz, Baiechu Kimchi, Yulmookimchi and Kakdooki were estimated during storage at the conditions of $5^{\circ}C$ and $25^{\circ}C Storage at $25^{\circ}C$ generally led to the more rapidly than that at $5^{\circ}C$. But changes of nitrite level showed very low variation in all tested Kimchi.

• Journal of the Korean Chemical Society
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• v.18 no.6
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• pp.415-420
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• 1974

A simple and rapid spectrophotometric method has been found for the determination of nitrate content in natural water according to brucine method by means of neither particular apparatus nor troublesome procedures. Brucine reacted with nitrate in the presence of 30 N sulfuric acid to develop stable color with good reproducibility after 30 minutes reaction at $60^{\circ}C$<\TEX>. An essentially linear relationship to the nitrate concentration was observed in the range of 0.07~0.6 ppm at 410 nm, and it was established that the number of absorbing species in the reaction system was only one between 400 and 490 nm. Among the interferences, nitrite could be removed by the addition of methanol.

• Journal of the Korean GEO-environmental Society
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• v.5 no.2
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• pp.23-31
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• 2004

Trichloroethylene(TCE), Cr(VI), and nitrate removal efficiency of a novel reactive barrier were experimented, and the types of corrosion species that form on the surface of the iron and bentonite as a result of reaction were investigated with Raman spectrophotometer. The reactive barrier is composed of bentonite and zero valent iron(ZVI), and this can substitute conventional geosynthetic clay liners for landfill leachate. Tests were performed in batch reactors for various ZVI content (0, 3, 6, 10, 13, 16, 20, 30, 100 w/w %) and pH. The reduction rates and removal efficiencies of TCE, Cr(VI) and nitrate increase at pH 7 buffered solution. As ZVI content increases, TCE, Cr(VI) and nitrate removal efficiencies increase. From the result of analysis with Raman spectrophotometer, Fe-oxides were observed, which are strong adsorbers of cantaminants. Magnetite can be also beneficial to the long term performance of the iron metal.