• Journal of Food Hygiene and Safety
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• v.17 no.2
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• pp.101-105
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• 2002

A total of 53 vegetables and fruits, consisting of 23 leaf vegetables, 4 fruits vegetables, 4 edible roots,7 spice vegetables and 15 fruits were analyzed for contents of nitrate and nitrite by ion chromatography. Nitrite was detected 10 of 23 kinds of leaf vegetables, which was dominant in lettuce by average 349.9 mg/kg. Nitrate contents of leaf vegetables were average 578.3 mg/kg, 415.7 mg/kg, 348.6 mg/kg in wild plant, mustard leaf and chinese vegetable, respectively. Nitrite was not detected in fruits vegetables and rootcrops but the nitrate contents were abundant and the highest in squash(average, 86.2 mg/kg) and radish(average, 297.5 mg/kg), respectively. In spice vegetables, mate contents were from 0 to 29.8 mg/kg, but not detected in garlic. In welsh onion, its nitrite were higher in small type than large type, while nitrate contents were higher 3 times in the latter. Nitrate contents of fruits were lower in apple(average, 0.5 mg/kg) and higher in plum(average, 76.6 mg/kg) than other samples.

• Korean Journal of Environmental Biology
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• v.18 no.4
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• pp.395-401
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• 2000

Growth and biochemical composition were analyzed in Gymnodinium sanguineum and Skeletonema costatum grown in media containing various nitrate and phosphate concentrations. Concentrations of nitrate and phosphate in the growth media were 0, 0.3, 0.6, 0.9, 1.2mM and 0, 15, 30, 45, 60 $\mu$M, respectively. Growth of G. sanguineum was suppressed in the low concentration of nitrate and phosphate (below N = 0.3 mM and P = 15 $\mu$M), whereas growth of S. costatum did not changed. At the low concentrations of nitrate and phosphate, amount of intracellular protein and carbohydrate in G. sanguineum cells were largely decreased, whereas content of carbohydrate in S. costatum cells was increased little. Amount of neutral lipid and phospholipid in G. sanguineum didn't changed, but concentration of glycolipid was largely decreased in the medium containing low concentrations of nitrate and phosphate. However the levels of TAG, glycolipid, and phospholipid did not changed in S. costatum cells. These results show that S. costatum is more adaptable than G. sanguineum in the low concentration of nitrate and phosphate.

• Journal of Life Science
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• v.17 no.5 s.85
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• pp.646-651
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• 2007

This investigation was performed to study the influence of Cd and nitrate on growth, and chlorophyll and photosynthetic enzymes in seedling of tobacco. Growth inhibition by Cd was not recovered by nitrate. Chlorophyll levels were reduced by Cd. The combination of Cd and low concentration of nitrate decreased the chlorophyll content compared to that in plants exposed only to Cd. Activity and content of rubisco at Cd treatment was significantly lesser than in plants receiving no treatment, These data suggest that rubisco activity was associated with an amount of rubisco protein, and that the activation and synthesis of rubisco is inhibited by Cd. Both the activity and content of rubisco decreased by Cd were more decreased by nitrate. A similar change pattern was also observed in activity and content of rubisco activase. These results suggest that Cd- and nitrate-induced changes of rubisco could be correlated with rubisco activase, and that nitrate was concerned in not only the activation and synthesis of rubisco directly, but also rubisco activase leading to a large change in rubisco.

• Korean Journal of Soil Science and Fertilizer
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• v.38 no.1
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• pp.38-44
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• 2005

In addition to the variation in nitrate accumulation of vegetables due to environmental conditions, there is also a distinct genetic variation. The variation of nitrate accumulation in some cultivars of lettuce and spinach commonly cultivated in Korea was investigated. Ten cultivars for both lettuce and spinach were grown in plastic containers filled with a 1:1 mixture of perlite and vermiculite with application of Hoagland No. 2 nutrient solution of high nitrate content (17.3 mM N) in a greenhouse condition. Plants were harvested four weeks after transplanting four-leaf stage seedlings. Plant growth was measured by fresh and dry matter of shoot, and contents of nitrate and other inorganic ions and organic solutes including sugar, amino acids and organic acids were measured. Large and significant genotypical variations in the nitrate content of the plants were found for both lettuce and spinach, and high negative correlations between nitrate content and fresh or dry weight were found in lettuce and spinach. Variation in nitrate accumulation of lettuce and spinach cultivars was not directly related to the differences in contents of organic and inorganic solutes, and this result indicates that photosynthesis and osmotic regulation are not directly related with the nitrate accumulation. Considering the correlations between nitrate content and plant growth of this study, it can be simply suggested that different cultivars of lettuce and spinach have their own inherited growth and physiological characteristics and also optimum nitrogen level required for the growth. Therefore when available nitrogen in root media is higher than the optimum level required for the inherited growth potential, some of the excess nitrate supplied can be accumulated in plants.

• Korean Journal of Environmental Biology
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• v.35 no.3
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• pp.373-379
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• 2017

Juvenile Paralichthys olivaceus (mean length $19.8{\pm}2.6cm$, mean weight $97.8{\pm}15.8g$) were exposed for 96 hours to different nitrate concentrations of 0, 62.5, 125, 250, 500, 1,000, and $1,500mg\;L^{-1}$ in biofloc and 0, 62.5, 125, 250, 500, and $1,000mg\;L^{-1}$ in seawater. Median lethal concentration values ($LC_{50}$, the concentration at which 50% of mortality occurred after 96 hours of exposure) of nitrate to P. olivaceus in biofloc and seawater were 1,226 and $597mg\;NO_3L^{-1}$ (P<0.05), respectively, revealing a higher toxicity of nitrate to P. olivaceus in seawater than in biofloc. In hematological parameters, hematocrit level in P. olivaceus exposed to nitrate was significantly increased only at a concentration of $1,000mg\;L^{-1}$ in biofloc and at concentrations higher than $250mg\;L^{-1}$ in seawater, but no significant changes in hemoglobin were found in biofloc and seawater. In plasma parameters, aspartate aminotransferase (AST) and alanine aminotransminase (ALT) were significantly increased by nitrate exposure in biofloc and seawater, but no significant changes in alkaline phosphatase (ALP) were found in biofloc and seawater. Results of this study indicate that nitrate exposure to P. olivaceus have a lethal toxic effect and alter hematological and plasma constituents of flatfish P. olivaceus. Given relatively lower toxicity of nitrate in biofloc than in seawater, the use of biofloc in aquaculture may reduce potential toxic effect caused by nitrate in feces and feed residue.

• Proceedings of the Korean Society of Fisheries Technology Conference
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• 2000.05a
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• pp.296-297
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• 2000

순환여과 시스템에서 사육어가 먹이를 섭취한 후 사육수 중에 배설하는 암모니아는 생물 여과조에서 질산화과정에 의해 독성이 적은 질산염으로 축적되는데, 이러한 질산염도 고농도로 축적되면 어류의 성장에 영향을 미치게 된다. 이 실험에서는 생물여과조에 탈질 시스템을 장치하여 효과적인 질산염 제거(Arbia and van Rijn, 1995; Whitson et al., 1993)를 위한 탈질 조건별 사육수질변화 및 이에 따른 실험어인 조피볼락, Sebastes schlegeli 및 큰민어, Nibea japonica의 성장에 미치는 영향을 조사하였다. (중략)

• Journal of Bio-Environment Control
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• v.14 no.3
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• pp.144-148
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• 2005

Kale leaf had similar contents of vitamin C, $NO_3$, p, Ca, Mg, and Fe with reported values. Among these internal quality factors, $NO_3$ content which has been a concern recently, ranged from 139 to 429 mg in 100 g fresh kale leaf, Kale showed high vitamin C content ranging from 106 to 203 mg in 100 g fresh leaf. The relative concentration of chlorophyll and b value color had a high correlation coefficient (r) with vitamin C, $NO_3$, Mg and Fe content. The relationship between $NO_3$ content and the relative concentration of chlorophyll was given by the following linear equation: $NO_3$ content : 21.55 + (5.907 ${\times}$ the relative concentration of chlorophyll) with an r of $0.910^{{\ast}{\ast}}$. Correlation between $NO_3$ content and b value was also very dependable (r = $-0.901^{{\ast}{\ast}}$). Vitamin C content and the relative concentration of chlorophyll showed a high correlation, r = $-0.858^{{\ast}{\ast}}$. Among internal quality factors, vitamin C content increased with decreasing $NO_3$ content and their correlation coefficient was high (r = $-0.795^{{\ast}{\ast}}$). Consequently, $NO_3$ content of kale leaf could be inferred from an external nondestructive method, such as the relative concentration of chlorophyll. We may be able to produce high quality kale leaves containing high amount of vitamin C and low content of $NO_3$ using this method.

• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
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• v.17 no.2
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• pp.120-129
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• 2012

We investigated seasonal variation of sediment-water oxygen and inorganic nitrogen fluxes, and denitrification at tidal flat sediments located in the Nakdong River Estuary from July 2005 to September 2006. Net oxygen fluxes, measured with sediment incubations at in situ temperature, varied from -37.0 to $0.5mmol\;O_2\;m^{-2}\;d^{-1}$. Oxygen fluxes into the sediments from the overlying water increased due to the increased water temperature. Denitrification rate ($4{\sim}2732{\mu}mol\;N\;m^{-2}\;d^{-1}$) in this study was higher compared to the other Korean coast measured with the same method. Denitrification showed the same seasonal variation as oxygen fluxes. Denitrification rate based on $^{15}N$-nitrate showed a strong correlation with nitrate flux into the sediments from the overlying water. Denitrification via "water column supplied nitrate ($D_w$)", calculated from Isotope pairing technique, also correlated well with nitrate flux into the sediments. Nitrate from water column seems to account for seasonal variation of denitrification in Nakdong River Estuary. To understand general patterns and trends of biogeochemical processes of sediments in the Nakdong River Estuary, we categorized biogeochemical fluxes measured in this study according to direction and sizes of fluxes. Type 1(high oxygen and inorganic nitrogen fluxes into the sediments and high denitrification) occurred in summer, whereas Type 2(low oxygen and inorganic nitrogen fluxes into the sediments and low denitrification) occurred in rest of the season. Intertidal flat sediments seem to react sensitively to influence of freshwater from the Nakdong River.

• Journal of The Korean Society of Grassland and Forage Science
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• v.19 no.1
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• pp.81-88
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• 1999

A field experiment with 200, 400 and $600kg{\cdot}N/ha/year$ application levels was carried out to study the nitrate nitrogen accumulation and forage yield of sorghum sudangrass hybrid(Xtragraze II) at Iksan College Farm in 1995. The nitrate nitrogen contents were increased by the application of nitrogen and decreased as the plant matured, then the accumulation of nitrate nitrogen started from 200kg application, and exceeded the safe level of ruminants at the level of 400kg application during the whole growing period. In the early stage of growth, nitrate nitrogen contents of sorghum sudangrass hybrid were increased by rainfall during the dry season, but these contents are almost kept constantly at the low level in the later stage of growth. Accumulation of nitrate nitrogen in the morning had a greater tendency than that of the afternoon. A sum exceeding $200kg{\cdot}N$ does not necessarily result in increase the amount of nitrate nitrogen in sorghum sudangrass hybrid.

• 한국생물공학회:학술대회논문집
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• 2003.10a
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• pp.392-396
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• 2003

Leaking underground storage tanks are a major source of groundwater contamination by petroleum hydrocarbons. Aerobic bioremediation has been highly effective in the remediation of many fuel releases. Bioremediation of aromatic hydrocarbons in groundwater and sediments is ofen limited by the inability to provide sufficient oxygen to the contaminated zones due to the low water solubility of oxygen. Nitrate can also serve as an electron acceptor And nitrate is less expensive and more soluble than oxygen. it may be more economical to restore fuel-contaminated aquifers using nitrate rather than oxygen. And denitrifying bacteria are commonly found in the subsurface and in association with contaminated aquifer materials. These studies have shown that BTEX and MTBE can be degraded by the nitrate-amended microcosms under aerobic and anaerobic conditons. Biodegradation of the toluene and ethylbenzne compounds occurred very quickly under denitrifying conditions. MTBE, benzene and p-xylene were recalcitrant under denitrifying conditions in this study.