• Korean Journal of Soil Science and Fertilizer
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• v.30 no.1
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• pp.23-28
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• 1997

A better understanding of nitrogen transformations in soils is essential to increase fertilizer nitrogen use efficiency. A laboratory incubation study was conducted to determine net mineralization and nitrification in selected Piedmont soils. Net mineralization and nitrification increased up to 60 days in the surface layers of Enon, Mecklenburg and Chewacla. After 60 days both processes declined up to 90 days incubation. In Wehadkee, mineralization and nitrification did not differ with incubation time. In all subsurface layers, mineralization and nitrification increased with time up to 90 days. Mineralization and nitrification differed among soils in surface and subsurface layers. These differences might be influenced by soil type related to amount of mineralization, soil aeration and nitrifying bacterial populations. A mineralization and nitrification was greater in surface layers than in subsurface layers.

• Journal of the Mineralogical Society of Korea
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• v.32 no.2
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• pp.113-126
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• 2019

This study aimed to effectively dissolve sulfide minerals through microwave-nitric acid leaching of invisible gold concentrate and then recover gold from the solid-residue with fire assay. For the purposes, this study conducted microwave-nitric acid leaching experiments to examine nitric acid concentration, time of microwave leaching, and sample addition effect. As results of the experiments, this study discovered that the weight loss rate of solid-residue increased as nitric acid concentration and microwave leaching time increased while weight loss rate decreased as sample addition increased. In an XRD analysis with solid-residue, it was discovered that pyrite completely disappeared when the nitric acid concentrate was 6 M and the microwave leaching time was 18 minutes. When a fire assay was carried out with solid-residue, gold particles with more content were recovered as nitric acid concentration and microwave leaching time increased whereas gold particles with more gold content were recovered as the sample addition decreased.

• Journal of fish pathology
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• v.5 no.2
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• pp.93-118
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• 1992

The research was carried out to examine the chronic toxic effects of nitrite on the Japanese eel, Anguilla japonica by neans of histological observations. Young eel, 10.8g mean body weight. were exposed to 6 different concentrations of nitrite(1, 5, 10, 20, 30 and 40ppm) for 10 weeks. Each concentration was treated under 5 different levels of pH(5.5, 6.0, 6.5, 7.0 and 7.5) and each of these treatment was tested at 2 different temperature regimes($25^{\circ}C$ and $30^{\circ}C$). Proper concentration of nitrite was made by $NaNO_2$ and proper pH levels were made by the combinations of 0.1M $KH_2PO_4$ and 0.1M $NaHCO_3$. Histopathological test of gill tissues were made along with the test of the formation of thrombocystes and chloride cells on the gill filaments. At the lower pH levels, mucus secretion from the gill was incrased as the nitrite concentration increased. As the level of nitrite increased the number of chloride cells on the gill filament were decreased. Most of the remained chloride cells were observed only at the terminar part of the gill filament at 40ppm of nitrite. Degeneration of gill tissues were observed when nitrite levels were over 10ppm along with detachement and sweption of the epithelial cells of the gill lamellae. Shrunken gill lamellae and formation of thrombosis in the capillaries of gill lamellae were also observed. When temperature goes higher at the higher level of nitrite, necroses in the gill lamellae was increased. At the lower than 10ppm of nitrite, degeneration of gill lamellae was occured at the beginning of the test period but regenerated later. Negative effects of nitrite on the growth of young eel was started between 5~10ppm at the pH level of 7.0 and 7.5. Thrombosis formation were also started at this level. The safety concentration of nitrite at the pH levels of 7.0 and 7.5 on the small eel seems to be 1ppm. Thrombosis and gill lamella detachment and necrosis in the gill capillaries were not observed at this level. Chloride cells were appeared the whole part of the gill filament.

• Proceedings of the Korea Air Pollution Research Association Conference
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• 2003.05b
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• pp.347-348
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• 2003

대기 중의 질산에 의해 생성되는 질산염은 해염성분이나 토양성분과 만나 조대입자 영역에 머물거나 암모늄과 만나 미세입자로 존재할 수 있다. 미세입자로 존재하는 질산염은 여름철과 같은 광화학 반응이 활발할 때 2차적으로 생성되는 물질로, 반휘발성 특성 때문에 측정하는 과정에서 오차가 발생할 가능성도 크다. Seinfeld (1986)에 의하면 미국의 도심 지역에서 미세입자 중 황산염이나 질산염 등 2차 이온 성분의 비율이 전체 입자의 40∼60 %를 차지한다고 보고되고 있으며, 대표적인 도심 지역인 서울에서도 비슷하다 (강충민 등, 1999). (중략)

• Proceedings of the Korean Institute of Surface Engineering Conference
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• 2016.11a
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• pp.127-127
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• 2016

일반적인 알루미늄 표면처리 방식중 De Smut 는 질산 50~60% 용액에 상온에서 수초에서 수분 침적으로 Smut가 거의 제거가 되므로 도금공정에서 문제가 되지않았다. 단지 NOx 의 발생으로 작업공간 에서의 환경이 열악해 질 수 있다는 것이 문제 였다, 그러나 환경문제에 있어서 정부의 질소 규제 가 시작 되면서 알루미늄을 재료로 표면처리 하는 업체 에서는 질산 사용이 곤란해 해졌다. 그러나 질산이 금속과 의 친화력은 스테인레스, 알루미늄, 등 많은 금속에서 소지금속의 용해를 방지 하면서 산화스케일( De Smut)을 제거하는 데 유용한 산이어서 아직도 이용되고 있는 실정이다. 본 연구에서 는 우선 스테인레스 강의 산세시 불산과 질산의 혼산을 사용 하는 것을 불산, 불화암모늄, 황산, 과산화 수소 혹은 불산, 염산, 과산화 수소 등으로 전환 사용 하는 것 에 착안 하여 황산, 과산화수소 시스템에서 혹은 불산, 황산, 과산화 수소, 등으로 Smut 제거가 가능 한지 알아보고 그 효과를 살펴보았다.

• Proceedings of the Korean Society of Soil and Groundwater Environment Conference
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• 2004.09a
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• pp.93-96
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• 2004

국내 대부분의 경작지를 차지하고 있는 논농사 지역에서의 질산성 질소의 자연저감을 고찰하기 위하여, 세 유형의 수조 환경을 조성하고 mesocosm 실험 연구를 수행하였다. 두개의 mesocosm에는 논토양을, 그리고 비교를 위하여 다른 하나에는 밭토양(황토)을 사용하였으며, 하나의 논토양 mesocosm과 밭토양(황토) mesocosm에는 벼를 재배하였다. 인위적으로 질산성 질소 성분을 용해한 지하수를 주입수로 사용하였으며, mesocosm을 통과한 물 시료를 41일 동안 12시간 또는 24시간 간격으로 채취하고 화학분석을 실시하였다. 실험 결과, 논토양에서는 실험 시작과 동시에 급격한 환원환경이 형성되었으며, 그 결과 탈질반응에 의해 질산성 질소의 농도가 현저히 저감되었다. 분석 자료의 해석 결과, 논토양 mesocosm에서는 유기물이, 밭토양 mesocosm에서는 철이온(Fe2+)이 질산성 질소의 탈질 반응에 중요한 역할을 수행하는 것으로 판단된다.

• Proceedings of the Korean Environmental Sciences Society Conference
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• 2006.05a
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• pp.401-402
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• 2006

본 연구는 서로 다른 조건에서 질산화를 유도한 반응기의 군집동태를 살피기 위해 DGGE를 이용하여 반응기 초기의 슬러지 구성 군집의 상태와 질산화 유도후의 군집변화를 살펴보고자 하였다. DGGE의 전체 profile에 의하면 군집을 조성하는 개체군의 수가 상당히 축소되었다는 점과 비배양적인 질산화균이 여전히 많다는 점, 그리고 호기조건과 미호기/무산소 조건에 공존하는 band가 많은 것으로 볼 때 예상보다는 산소에 대해 내성이 있는 질산화균이 많다는 것을 알 수 있었다.

• Proceedings of the Korean Institute of Resources Recycling Conference
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• 2005.10a
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• pp.281-288
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• 2005

실리콘웨이퍼 제조공정에서 발생되는 초산, 불산 및 질산을 함유한 폐혼산으로 부터 각 산을 분리한 후 재활용하기 위하여 기초 실험을 실시하였다. 용매추출 법을 이용하여 초산, 불산 및 질산을 분리하기 위해 최적 추출제를 선정 하였고, 단일 성분에서의 추출 및 탈거특성에 관해 조사하였다. 또한, 이성분계 혼합산에서 분배비를 조사하여 상호 분리성에 대해 검토하였다. 실험 결과 인산염계 추출제는 고급 알코올에 비해 각 산의 추출 능력이 높다는 것을 확인하였다. 초산과 질산의 이성분 혼합액에서는 고급 알코올을 사용하면 초산이 분배비가 높아 선택적으로 추출되는 것을 확인하였고, 초산과 불산의 이성분 혼합액에서도 인산염계 추출제 보다 고급 알코올 사용시 초산의 분배비가 높아 선택적으로 추출됨을 확인하였다. 한편, 질산과 불산의 혼합액에서는 인산염계 추출제를 사용하여 질산이 선택적으로 추출됨을 확인하였다.

• KSBB Journal
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• v.18 no.6
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• pp.461-465
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• 2003

Five denitrifying bacteria, which were identified as Pseudomonas sp., were isolated by the enrichment culture technique. The most effective denitrifying bacterium was named as Pseudomonas DWS, which was cultivated at anoxic condition. The optimal growth temperature and pH were 30$^{\circ}C$ and 7-8, respectively. Cell growth almost revealed a stationary phase at 18 hours after cultivation and nitrate was degrade 99.9％ during this period. Therefore, it is suggested that Pseudomonas DWS could be effectively used for the biological treatment of wastewater containing nitrogen compounds.

• 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.