• Korean Journal of Soil Science and Fertilizer
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• v.20 no.3
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• pp.223-229
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• 1987

This study was carried out to find out the effects of nitrogen dioxide gas on vegetable crops. Chinese cabbage, radish, tomato and cucumber were used for this experiment, and these crops were fumigated with various concentration of nitrogen dixoide gas for 2 hours under the different condition of light and soil water at the vegetable growth stage. The results obtained were as follows. The crops damages measured by percentage of leaf destruction were more severe at the night time fumigation than at the day time, under the full sun condition than under the shading, and at the higher soil water contents than at the low soil water contents. The cucumber plant showed the highest resistance to nitrogen dioxide gas and tomato plant showed the least resistance. As the nitrogen dioxide concentration increased from $0.05mg/{\ell}$ to $0.2mg/{\ell}$, the N contents in leaves of each crops were increased, and the increment of N contents in leaves was higher by fumigation at the night than at the day time. The increment of N contents in leaves showed possive correlation with the percentage of leaf destruction significantly.

• Economic and Environmental Geology
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• v.43 no.1
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• pp.43-52
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• 2010

The geochemical and nitrogen isotopic analyses for shallow groundwater of Ogcheon area were carried out to characterize the geochemical characteristics of the groundwater and to identify the source of nitrate. Groundwater shows a neutral pH to weakly alkalic condition with pH values ranging from 6.9 to 8.4. The average of EC, Eh and DO is $344.2\;{\mu}s/cm$, 195 mV, 4 mg/L, respectively. According to piper diagram, chemical composition of groundwater is dominantly characterized by Ca-$HCO_3$ type. On the other hand, groundwater type in the study area include Ca-Cl+$NO_3$ type that were highly influenced by agricultural activities. $NO_3$-N concentration of the collected samples(n=45) range from 12.4 to 34.2 mg/l. These data show that the $NO_3$-N concentration exceeds Korea Drinking Water Standard (10 mg/l). The $\delta^{15}N-NO_3$ values range from $2.7^{\circ}/_{\circ\circ}$ to $18.8^{\circ}/_{\circ\circ}$. The enrichments of heavy isotope in the groundwater indicate that major origin of nitrate pollution were associated with animal and human waste. Also the denitrification may have partly contributed as one of the sources of nitrogen.

• Journal of Korean Society of Environmental Engineers
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• v.27 no.7
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• pp.686-689
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• 2005

This study was conducted to investigate the effect of ammonium and nitrate nitrogen removal to applied voltage, electrolytic time and activated carbon packing height. Batch bipolar packed bed electrolytic cell reactor was packed with $4{\times}8$ mesh granular activated carbon (GAC). Afterward electrolysis was performed in 20 V for 30 min. As a result, as the filling height adjusted to 80 mm high, the removal efficiency of ammonium nitrogen was 99.9%. and as the electrolytic time varied to 60 min, the removal efficiency of ammonium nitrogen was 97.6%. and in case of continuous electrolytic treatment of ammonium and nitrate nitrogen removal efficiency of total nitrogen was over 80% in bipolar packed bed electrolytic cell reactor for 72 hours as the packing height, sample concentration and input rate of sample adjusted to 280 mm, 30 mg/L, 6.7 mL/min, respectively.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.35 no.4
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• pp.431-437
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• 2002

In order to understand the spatiotemporal variation of water quality, an investigation on variation characteristics of water quality was conducted at 13 stations in Yongil bay from 1990 to 1998. The salinity in summer was relatively lower than that in other seasons and it have increased from inner bay to outside of the bay gradually. However, nitrate concentration in summer was relatively higher than that in other seasons, and it was the highest, up to $65.40\%$, among dissolved inorganic nitrogens, Nitrate concentration indicates the possibility of affecting by freshwater discharges to Yongil bay. Correlation analysis showed that salinity had a significantly good correlation with nitrate. This result suggested that inflow of river had an influence on increase of nitrate. The result of Principal Component Analysis (PCA) indicated that nitrate was major factor to influence the water quality in Yongil Bay.

• Journal of the Korean Society of Food Science and Nutrition
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• v.43 no.8
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• pp.1207-1216
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• 2014

Vegetables contain high levels of nitrate, which can be converted to nitrite for reaction with secondary amines to form nitrosamines. In this study, we evaluated safety effects against nitrite and nitrosamine as well as anti-mutagenic activities of vegetable juices. To do this, the contents of nitrate, nitrite, and nitrosamines were determined in vegetable juices. The safety effects against nitrite and nitrosamine formation were also investigated under simulated human gastric conditions. The contents of nitrate and nitrite in common and organic kale and Angelica keiskei juices were 931~2,052 mg/kg and 13~82 mg/kg, respectively. However, seven kinds of nitrosamines were not detected in the vegetables juices. The nitrate content decreased when vegetable juices were digested under simulated human gastric conditions. Nitrosamine (N-nitrosodimethylamine) formation under simulated human gastric conditions was inhibited by addition of vegetable juices. In addition, vegetable juices, especially organically cultivated juices, showed anti-mutagenic effects in a Salmonella assay system. These results suggest that organically cultivated vegetable juices are a promising health-promoting source.

• KSBB Journal
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• v.24 no.2
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• pp.195-200
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• 2009

The effect of nitrogen source on cell growth and benzo[c]phenanthridine alkaloids production by modifying $NO_3\;^-:NH_4\;^+$ ratio in cell suspension culture of Eschscholtzia califarnica was investigated. When total nitrogen concentration is maintained (60 mM), maximum benzo[c]phenanthridine alkaloids production is about 60.72 mg/L at 50:10 (mol/mol). This productivity was 3.8 times higher than that obtained when cells were grown instandard MS medium. The decrease of $NO_3\;^-:NH_4\;^+$ ratio at 60 mM of total nitrogen caused the decline of both growth and benzo[c]phenanthridine alkaloids production. Under the same concentration of $N0_3\;^-$ (50 mM), higher concentration of $NH_4\;^+$ inhibited cell growth strongly but induced alkaloids production slightly. Also, under the same concentration of $NH_4\;^+$ (25 mM), higher concentration of $N0_3\;^-$ induced alkaloids production strongly but high concentration of $N0_3\;^-$ (${\geq}$100 mM) interfered alkaloids instead. Maximum benzo[c]phenanthridine alkaloids production is about 62.71 mg/L at 50:25 (mol/mol). These results suggest that higher biomass and higher alkaloids production could be obtained by optimizing each nitrogen concentration as well as $NO_3\;^-:NH_4\;^+$ ratio in the culture medium. Nitrate and ammonium in culture medium have distinct role in the regulation of growth and alkaloids production; ammonium had a strong influence on growth while nitrate had an influence on alkaloids production.

• Journal of the Korean GEO-environmental Society
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• v.8 no.4
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• pp.19-25
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• 2007

Process analysis with ASM3 (Activated Sludge Model3) was performed to offer basic data for the optimization of aerated biofilter (ABF) process design and operation. This study was focused on the simulation of the nitrification reaction in ABF which was a part of the advanced nutrient treatment process using bio-adsorption. The ABF process has been developed for the removal of suspended solids and nitrification reaction in sewage. A GPS-X (General Purpose Simualtor-X) was used for the sensitivity analysis and operation assessment. Sensitivity of ASM3 parameters on ABF was analysed and 4 major parameters ($Y_A$, $k_{sto}$, ${\mu}_A$, $K_{A,HN}$) were determined by dynamic simulation using 70 days data from pilot plant operation. The optimized values were 0.14 for $Y_A$, 3.5/d for $k_{sto}$, 2.7/d for ${\mu}_A$ and 1.1 mg/L for $K_{A,HN}$, respectively. Simulation with optimized parameter values were conducted and TN, $NH_4{^+}-N$ and $NO_3{^-}-N$ concentrations were estimated and compared with measured data at the range of 10 min to 4 hrs of hydraulic retention time (HRT). The simulated results showed that optimized parameter values could represent the characteristics of ABF process. Especially, the ABF showed relatively high nitrification rate (60%) under very short HRT of 10 min. As a consequence, the ABF was thought to be successfully used in the site which having high variation of influent loading rate.

• Journal of Korean Society of Environmental Engineers
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• v.22 no.1
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• pp.141-148
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• 2000

In this study, effects of substrates and nitrate on biological phosphorus release in EBPR(enhanced biological phosphorus removal) process were examined using batch test apparatus at anaerobic conditions. The sludge used in this experiments was taken from SBR(sequencing batch reactor) treating swine wastewater at aeration period. Phosphorus release rates obtained with substrates of FSW(fermented swine wastewater), acetate, propionate, domestic wastewater and methanol were 6.19, 5.99, 1.52, 1.2 and $1.03mgP/gVSS{\cdot}hr$, respectively. Those observed with acetate and FSW were 4~5 times greater than those with propionate, methanol and domestic wastewater. Therefore phosphorus release rates were significantly affected by type of substrate added at anaerobic condition. Phosphorus release was greatly affected by concentration of nitrate in anoxic condition. Comparing to acetate, propionate and FSW, phosphorus release was observed after almost completely depletion of nitrate concentration with methanol and domestic wastewater added as substrate. In the cases supplied with acetate, propionate and FSW, phosphorus release rates were less influenced by a nitrate concentration than those with methanol and domestic wastewater.

• Journal of Korean Society of Environmental Engineers
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• v.31 no.7
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• pp.515-520
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• 2009

This study investigated the influence of oxyanions (nitrate, carbonate, phosphate) on the attachment of bacteria (Bacillus subtilis) to Al-Fe bimetallic oxide-coated sand using column experiments. Results showed that bacterial attachment to the coated sand was independent of nitrate concentration. Bacterial mass recovery remained constant (10.9${\pm}$0.2%) with varying nitrate concentrations (0.1, 1, 10 mM). In case of carbonate, mass recovery increased from 25.6% to 39.0% with increasing carbonate concentration from 0.1 mM to 1 mM, and mass recovery also increased from 50.9% to 78.9% at the same concentration condition in case of phosphate. This phenomenon could be attributed to the hindrance effect of carbonate and phosphate to bacterial attachment to the coated sand. Meanwhile, with increasing carbonate/phosphate concentration from 1 mM to 10 mM, mass recovery decreased from 39.0% to 23.8% and from 78.9% to 52.6%, respectively. This phenomenon could be ascribed to the enhancement effect of free carbonate/phosphate ions present in solution phase due to increasing carbonate/phosphate concentration, which increase ionic strength and thus enhance bacterial attachment to the coated sand. In our experimental conditions, the effect of phosphate to bacterial attachment to the coated sand was the greatest among phosphate, carbonate, and nitrate.

• Korean Journal of Soil Science and Fertilizer
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• v.30 no.1
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• pp.16-22
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• 1997

Determination of N mineralization and nitrification potentials of selected Piedmont soils of North Carolina requires a better understanding of the influences of incorporated plant residues. The net N mineralization and nitrification were significantly influenced by the soil types and by plant species. The net N mineralization and nitrification of soils mixed with plant residues were consistently increased with successional incubation periods. The net mineralization and nitrification ranged from $9.77{\mu}g/g$ to $143.80{\mu}g/g$, and from $5.31{\mu}g/g$ to $145.66{\mu}g/g$ during the incubation periods, respectively. The net N mineralization was more influenced by NO3-N than by NH4-N. Overall, the greatest proportions of net N mineralization and nitrification occurred in Chewacla and Wehadkee and lowest in Enon and Mecklenburg. For the plant residues, the net N mineralization and nitrification were observed to be lowest in corn and highest in soybean. In a low-input agricultural systems, soybean may be planted as cover crop which may improve the nitrogen status of selected Piedmont soils of North Carolina.