• Journal of the korean society of oceanography
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• v.32 no.4
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• pp.191-201
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• 1997

To test the roles of NO$_3^-$ concentration and light as controlling factors of NO$_3^-$ uptake in the NO$_3^-$-low and -high environments and to assess the significance of night-time nitrogen (N) uptake in estimating the daily N uptake rate, 2 diel studies of N uptake were conducted in NO$_3^-$-low (the eastern part of the Yellow Sea) and NO$_3^-$-high (the marginal ice zone of the northwestern Weddell Sea) environments on June 14 to 15, 1996 and January 15 to 16, 1995, respectively. Ourobservations confirmed that NO$_3\;^-$ uptake by phytoplankton is mainly determined by ambient NO$_3^-$ concentration in NO$_3^-$-low environment and by light in NO$_3^-$-high environment, respectively, Our results suggest the need for diel studies to accurately estimate the daily N uptake rates and thus new and regenerated production because the daily rates calculated without considering the night-time N uptake would be significantly underestimated (up to 41%), particularly in the NO$_3^-$-low environment.

• Journal of Bio-Environment Control
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• v.5 no.2
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• pp.120-130
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• 1996

Crisphead lettuce(Lactuca sativa L.) was grown in NFT to investigate the effects of NO$_3$-N and NH$_4$-N ratio in nutrient solution and elevated $CO_2$ treatment in the crisphead lettuce growth. This experiment has been conducted under three different ratios of NO$_3$-N:NH$_4$-N(100:0, 75:25, 50:50) with two $CO_2$ concentration (control, 1500ppm ). The results are as follows; 1. In the case of not controlling pH and EC in nutrient solution, pH was gradually increased in NO$_3$-N:NH$_4$-N=100:0 treatment but rapidly decreased in the nutrient solution 2. Daily changes of NO$_3$-N and NH$_4$-N were observed without controlling the nutrient solution. In the treatments of NO$_3$-N:NH$_4$-N ratios were 75:25 and 50:50, NO$_3$-N absorption rates were 27.7% and 26.1%, while NH$_4$-N absorption rates were 87.9% and 71.2%, respectively. 3. There was little differences in total nitrogen of leaves. However phosphorus, potassium, calcium and magnesium contents were highly shown in the treatment of $CO_2$ 1500ppm and 100:0 ratio of NO$_3$-N:NH$_4$-N. 4. Higher $CO_2$ assimilation rate was shown in plants grown under $CO_2$ 1500ppm and 100:0 ratio of NO$_3$-N:NH$_4$-N. It dropped significantly with the increase of NH$_4$- N rates in nutrient solution. 5. Fresh weight, leaf number, root length and root weight of crisphead lettuce were far better in the treatment of $CO_2$ 1500ppm and 100:0 ratio of NO$_3$-N:NH$_4$-N. Growth differences by $CO_2$ elevation were not shown in other NO$_3$-N:NH$_4$-N treatments. 6. The highest nitrate contents of leaves were shown in NO$_3$-N single treatment but shown the lowest vitamin C contents. Nitrate contents of leaves were decreased by $CO_2$ but the effect was slight treatment.

• Bulletin of the Korean Chemical Society
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• v.35 no.4
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• pp.1117-1120
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• 2014

Ru/C-catalyzed hydrogenation of m-xylylene diamine into 1,3-cyclohexanebis(methylamine) was greatly accelerated by the presence of $LiNO_3$, $NaNO_2$, or $NaNO_3$. It was found that the effect of the nitrate salt was significantly affected by the size of cation. The promoting effect of the nitrate salt increased with the decrease of the cation size: $LiNO_3$ ~ $NaNO_2$ > $KNO_3$ > $CsNO_3$ >> [1-butyl-3-methylimidazolium]$NO_3$. XRD analysis of the recovered catalysts after the hydrogenation reactions showed that $LiNO_3$ and $NaNO_2$ were completely transformed into LiOH and NaOH, respectively, along with the evolution of $NH_3$, while $KNO_3$ and $CsNO_3$ remained unchanged.

• Journal of Korean Society for Atmospheric Environment
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• v.32 no.4
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• pp.422-434
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• 2016

This study was conducted to understand roles of $NO_x(=NO+NO_2)$ on high $O_3$ episodes at an urban monitoring station in Seoul. Concentrations of NO, $NO_2$, $NO_y$ and $O_3$ were measured intensively at KIST monitoring station which located at urban center in Seoul metropolitan area during May 18~June 13, 2015. Sampling period was planed because high $O_3$ and PM occurred frequently during from late spring to early summer months in Seoul. The experimental site locates in NW from center of Seoul and is surrounded by residential area. Belt highway of the city runs from north to west side nearby experimental site. Vehicle exhaust emissions due to heavy traffic influenced $NO_x$ concentration at the site during northwesterly wind. Specific $NO_2$ concentration was measured by Blue Light photolytic converter, and it was compared to $NO_2$ concentration measured by molybedenum converter. $[NO_2]_{phtolysis}$ was usually lower than $[NO_2]_{molybedenum}$ during the experiment period; however their diurnal variations were very similar. The linear relationship between these $NO_2$ concentrations was found to be $[NO_2]_{phtolysis}$=0.64 $[NO_2]_{molybedenum}$ - 2.6, $r^2$=0.83 during May 16~8, 2015. The difference between $NO_2$ by molybdenum converter and by photolytic converter (${\Delta}NO_2=[NO_2]_{molybedenum}-[NO_2]_{phtolysis}$) accounted for residual $NO_y$ which can represent $NO_z$ (=$NO_y-NO_x$). $O_3$ concentration showed typical daily trend which has maximum at late afternoon and minimum during the night. $O_3$ increased at a rate of 7 ppb/hr since 8 am. and reached the maximum concentration (~80 ppb) at 3 pm.. The diurnal pattern of $O_3$ was inversely related with that of $NO_2$, suggesting that the formation of $O_3$ was the result of photochemical activity of $NO_2$.

• Bulletin of the Korean Chemical Society
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• v.32 no.spc8
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• pp.3039-3044
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• 2011

This study suggests the prediction model for the concentration variation of $NO_2{^-}$ and $NO_3{^-}$ along with the rate constants of all reactions during ozonation under UV radiation ($O_3$/UV process). While $NO_2{^-}$ was completely converted into $NO_3{^-}$ during the $O_3$-only process, the production of $NO_2$ radical or $N_2O_4$ was expected in the $O_3$/UV process. In addition, the quenching of OH radicals, by $NO_2$ radical in the $O_3$/UV process, resulted in regeneration of $NO_2{^-}$. However, the regeneration of $NO_2{^-}$ was not observed in the $O_3$/UV process in the presence of $C_6H_6$ where the concentrations of $NO_2{^-}$ and $NO_3{^-}$ were significantly reduced compared to in the process without $C_6H_6$. The pseudo-first order rate constants of all species were calculated with and without the presence of $C_6H_6$ to predict the variation of concentrations of all species during the $O_3$/UV process. It was suggested that $NO_2{^-}$ and $NO_3{^-}$ in the $O_3$/UV process can be more effectively removed from an aqueous system with an OH radical scavenger such as $C_6H_6$.

• Journal of Bio-Environment Control
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• v.3 no.2
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• pp.99-105
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• 1994

The objective of this study was conducted for elucidation of effects of the NO$_3$$^{[-10]}$ -N. NH$_4$$^{+}$-N ratio in the nutrient solution on the growth and quality of welsh onion(Allium fistulosum L.). The pH of nutrient solution increased in NO$_3$$^{[-10]}$ -N : NH$_4$$^{+}$-N ratio of 9 : 1 treatment, decreased in 1 : 1, 1 : 3 treatment, but was stable in 3 : 1 treatment during cultivation. The apparent growth of welsh onion was best in the treatment of 9 : 1(NO$_3$$^{[-10]}$ -N : NH$_4$$^{+}$-N ratio), however the treatment of 1 : 3 resulted in poor growth. The NO$_3$$^{[-10]}$ -N content of the plants increased in proportion to that content of nutrient solution. Pyruvic acid content of welsh onion was highest at 9 : 1, 3 : 1 treatment, and lowest at 1 : 3 treatment.tment.

• Asian Journal of Atmospheric Environment
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• v.12 no.1
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• pp.17-29
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• 2018

For the first time in the city of Riyadh, the formation of $O_3$ and its relationship with NO and $NO_2$ ($NO_x$) was investigated. Throughout the summer $O_3$, NO, and $NO_2$ were collected from three locations: residential, industrial, and rural areas. During the sampling period $O_3$ concentrations exceeded 1-hour local standards a few times yet remained consistent with the standards most of the time. The $O_3$ concentrations were observed highest in the rural location and lowest in the industrial area. The diurnal variation of NO followed a double peak: one in the morning and the other in the evening, representing the traffic pattern. Early morning NO peaks were observed in the rural location, which were attributed to the movement of NO from other locations. The $O_3$ concentrations depicted typical pattern, increasing after sunrise and reaching its maximum during midday. The highest $O_3$ concentrations were observed in the rural location followed by the residential and industrial. $NO_2$ photolysis rates were 3-4 times higher compared to other similar investigations, potentially due to intense solar radiation. A strong negative correlation was observed between $NO_x$ and $O_3$ values in the industrial location indicating photochemical activities around the industrial area were higher, likely due to additional $NO_x$ emissions from industries. Regression analysis of $NO_x$ and OX ($O_3+NO_2$) indicated that in residential and industrial locations at nighttime there were large $NO_x$ independent regional contributions which is attributed to VOCs. The Weekend Effect was observed in the city potentially due to the production of the OH radical and subsequent reactions with VOCs implying that the area is VOC-sensitive.

• Journal of Nuclear Fuel Cycle and Waste Technology(JNFCWT)
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• v.9 no.3
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• pp.121-129
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• 2011

The effects of the applied current density, the $AgNO_3$ concentration, the scrubbing liquid flow rate and the NO-air mixed gas flow rate on the NO removal efficiency were investigated by using $Ag^{2+}$ mediated electrochemical oxidation (MEO). Results showed that the NO removal efficiency increased with increasing the applied current density. The effect of the $AgNO_3$ concentration on the NO removal efficiency was negligibly small in the concentration of $AgNO_3$ above 0.1 M. When the scrubbing liquid flow rate increased, the NO removal efficiency was gradually increased. On the other hands, the NO removal efficiency decreased with increasing the NO-air mixed gas flow rate. As a result of the treatment of NO-air mixed gas by using the MEO process with the optimum operating condition and the chemical absorption process using 3 M $HNO_3$ solution as a scrubbing liquid, the removal efficiency of NO and $NO_x$ was achieved as 95% and 63%, respectively.

• Journal of Korean Society for Atmospheric Environment
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• v.8 no.1
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• pp.68-73
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• 1992

A study on the formation of particulate nitrate$(NO_3^-)$ and gaseous nitrate$(HNO_3)$ in the atmosphere was carried out in Seoul from Oct 8 to 11 1991. To collect $NO_3^-$ and $HNO_3$ in the ambient air, dual filter pack sampler (47mm$\phi$) was used. In the dual filter pack sampler, the first filter was Teflon filter (poresize 1$\mum$) for collection of $NO_3^-$ and the second filter was Nylon filter (poresize 0.45 $\mum$) for $HNO_3$. Particulate nitrate$(NO_3^-)$ and Sulfate ions were analysed by Ion chromatography. $HNO_3$ concentration was higher in the day time $(9.93\mug/m^3)$ than the night time$(3.50\mug/m^3)$, and Particulate nitrate$(NO_3^-)$ concentration was higher in the night time and early morning$(6.21\mug/m^3)$ than the day time$(4.31\mug/m^3)$. The conversion rate of $NO_x$ to total nitrate$(NO_3^-, HNO_3)$ was 7.57%/hr in the day time and 4.79%/hr in the night time, and total average conversion rate was 5.60%/hr.

• Transactions of the Korean Society of Automotive Engineers
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• v.16 no.5
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• pp.68-76
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• 2008

Diesel $NO_x$ reduction by $NH_3$-SCR in conjunction with the effective oxidation precatalyst was analytically investigated. Physicochemical processes in regard to $NH_3$-SCR $NO_x$ reduction and catalytic NO-$NO_2$ conversion are formulated with detailed descriptions on the commanding reactions. A unified model is correctly validated with experimental data in terms of extents of $NO_x$ reduction by SCR and NO-$NO_2$ conversion by DOC. The present deterministic model based on the rate expressions of Langmuir-Hinshelwood reaction scheme finds a conversion extent directly. A series of numerical experiments concomitant with parametric analysis of the $NO_x$ reduction was conducted. $NO_x$ reduction is promoted in proportion to DOC volume ar lower temperatures and an opposite holds at lower space velocity and intermediate temperatures. $NO_x$ conversion is weakly correlated to the space velocity and the DOC volume at higher exhaust temperature. In DOC-SCR system, the $NO_x$ reduction efficiency depends on the $NH_3/NO_x$ ratio.