• 한국농업기계학회:학술대회논문집
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• 한국농업기계학회 2017년도 춘계공동학술대회
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• pp.122-122
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• 2017

Recently, environmental problems have become an area of growing interests. In-situ monitoring of water quality is fundamental to most environmental applications. The accurate measurement of nitrate concentrations is fundamental to understanding biogeochemistry in aquatic ecosystems. Several studies have reported that one of the most feasible methods to measure nitrate concentration is the use of Ion Selective-electrodes (ISEs). The ISE application to water monitoring has several advantages, such as direct measurement methodology, high sensitivity, wide measurement range, low cost, and portability. However, the ISE methods may yield inconsistent results where there was a difference in temperature between the calibration and measurement solutions, which is associated with the temperature dependence of ionic activity coefficients in solution. In this study, to investigate the potential of using the combination of a temperature sensor and nitrate ISEs for minimizing the effect of temperature on real-time nitrate sensing in natural water, a prototype of on-site water monitoring system was built, mainly consisting of a sensor chamber, an array of 3 ISEs, an waterproof temperature sensor, an automatic sampling system, and an arduino MCU board. The analog signals of ISEs were obtained using the second-order Sallen-key filter for performing voltage following, differential amplification, and low pass filtering. The performance test of the developed water nitrate sensing system was conducted in a monitoring station of drinking water located in Jeongseon, Kangwon. A temperature compensation method based on two-point normalization was proposed, which incorporated the determination of temperature coefficient values using regression equations relating solution temperature and electrode signal determined in our previous studies.

• 한국초지조사료학회지
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• 제20권4호
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• pp.265-274
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• 2000

To investigate the effects of anion replacement on NO3- concentration in Italian ryegrass. Plants weregrown hydroponically to the full vegetative stage. NO3 supply(control) was replaced with SO1- (Tl), C1-(T2) and water (T3) to during 14 days. The determination of inorganic nutrient uptake and quantification ofprincipal metabolites (nitrate. protein and sugar) followed. Relatively high uptake of ~ a a'n d Ca" for controlplants, K+ and POJ- for T2 plants, and C 1 for TI plants was observed, respectively. Proteins in shoot andstubble were relatively higher in control and TI plants, which coupled N source. In root proteins largelydecreased (especially in T3 plants) during experimental period. Sugars in shoot of all four treatments tendedto decrease during the first 7 days and recovered afterward. Sugars in stubble also markedly decreased duringthe first 7 days, while those in root was much less varied during experimental period. After 14 days oftreatment, nitrate concentration in shoot of control plants was 13mgIg FW. Comparing to control: nitrate inshoot reduced by 27%, 46% and 50% in TI, T2 and T3 plants, respectively. Dry weight was slightlyincreased or not significantly changed in control, T1 and T2 plants, while a significant decrease(31.3% ofcontrol) occurred in T3 plants.(Key words : Italian ryegrass, Anion replacement, Ion uptake, Protein, Sugar, Nitrate)ptake, Protein, Sugar, Nitrate)

• 한국환경농학회지
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• 제27권3호
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• pp.279-284
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• 2008

We investigated whether carboxylate exudation of Brassica pekinensis Rupr. was affected by nitrate deposition from simulated acid rain. A gas chromatographic (GC) analysis was employed for the determination of low molecular weight organic acids (LOA) in rhizosphere soils, bulk soil, roots and leaves of Brassica pekinensis Rupr.. Rhizosphere soils were collected after 8 weeks of plant growth by first removing the bulk soil from the root system and then by mechanical move off the rhizosphere soil that adhered to the root surface with soft brush. Soil and plant materials were simultaneously extracted with the mixture of methanol and sulfuric acid (100:7, v/v). Seven organic acids, oxalic, malonic, fumaric, succinic, maleic, L-malic and citric acid were identified and quantified by GC equipped with FID. Oxalic, L-malic, and citric acids were found in both the bulk and rhizosphere soils, while most LOAs were not detected in the control treatment. On the contrary, except maleic acid, all other organic acids were detected in the leaves and roots of cabbages treated with nitrate deposition.

• 한국지하수토양환경학회지:지하수토양환경
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• 제26권6호
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• pp.74-81
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• 2021

A simple and efficient scheme is presented that attempts to implement the site-specific denitrification rate in the reactive transport modeling for the nitrate in groundwater. A series of correlation analyses were conducted using 133 datasets obtained from different nitrate-contaminated sites to find the empirical relationships between denitrification rates and various subsurface properties. Based on Pearson's correlation analysis, the soil organic carbon concentrations showed a statistically significant correlation (r = 0.75, p < 0.05) with the denitrification rates. A linear regression was performed, which could be utilized to effectively determine the site-specific denitrification rate based on the soil organic carbon concentration of a site. The proposed method is expected to effectively replace the conventional methods which either were too complicated for practical application or impose large uncertainties that might end up with unreliable results.

• 한국연초학회지
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• 제35권1호
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• pp.1-6
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• 2013

Near InfraRed Spectroscopy(NIRS) is a quick and accurate analytical method to measure multiple components in tobacco manufacturing process. This study was carried out to develop calibration equation of near infrared spectroscopy for the prediction of the amount of chemical components and hot water solubles(HWS) of reconstituted tobacco leaf. Calibration samples of reconstituted tobacco leaf were collected from every lot produced during one year. The calibration equation was formulated as modified partial least square regression method (MPLS) by analyzing laboratory actual values and mathematically pre-treated spectra. The accuracy of the acquired equation was confirmed with the standard error of prediction(SEP) of chemical components in reconstituted tobacco leaf samples, indicated as coefficient of determination($R^2$) and prediction error of sample unacquainted, followed by the verification of model equation of laboratory actual values and these predicted results. As a result of monitoring, the standard error of prediction(SEP) were 0.25 % for total sugar, 0.03 % for nicotine, 0.03 % for chlorine, 0.16 % for nitrate, and 0.38 % for hot water solubles. The coefficient of determination($R^2$) were 0.98 for total sugar, 0.97 for nicotine, 0.96 for chlorine, 0.98 for nitrate and 0.92 for hot water solubles. Therefore, the NIRS calibration equation can be applicable and reliable for determination of chemical components of reconstituted tobacco leaf, and NIRS analytical method could be used as a rapid and accurate quality control method.

• 임산에너지
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• 제22권3호
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• pp.29-36
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• 2003

본 논문은 중국 장백산 북사면의 5가지 산림 군집에서 우세목의 잎 내 질소 환원 효소의 활성도를 보다 개량된 방법을 적용하여 측정 분석한 내용을 다루었다. 질소 환원 효소의 활성도는 수목의 내음성과 연관이 깊은 것으로 파악되어, 양수일수록 질소 환원 효소의 활성도가 높은 것으로 측정되었다. 또한 질소 환원 효소의 활성도는 산림내의 수직적 구조와 생태적 입지 조건과 연관이 깊은 것으로 나타났다. 질소 환원 효소의 활성도가 높은 수종들은 생장이 빠르고 생산력이 높은 것으로 판단된다.

• Bulletin of the Korean Chemical Society
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• 제27권6호
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• pp.875-880
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• 2006

A new, simple and fast flow injection analysis (FIA) method has been developed for the indirect determination of nitrite. The proposed indirect automatic method is based on the oxidation of nitrite to nitrate using a lead(IV) dioxide oxidant microcolumn where the flow of the sample through the microcolumn reduces the $PbO_2$ solid phase reagent to Pb(II), which is measured by flame atomic absorption spectrometry. The absorbance of Pb(II) are proportional to the concentration of nitrite in the samples. The calibration curve was linear up to 30 mg $L ^{-1}$, with a detection limit of 0.11 mg $L ^{-1}$ for a 400 mL injected sample volume and a sampling rate of about 80 $h ^{-1}$. The results exhibit no interference from the presence of large amounts of ions. The developed procedure was found to be suitable for the determination of nitrite in foodstuffs and wastewaters. A relative standard deviation better than 0.9% was obtained in a repeatability study. The reliability of the method was established by parallel determination against the standard method.

• 대한화학회지
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• 제41권5호
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• pp.256-265
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• 1997

토양과 수질시료 중에서 nitrite, nitrate 그리고 ammonia성 질소를 빠르고 연속적으로 정량할 수 있는 방법에 관하여 연구하였다. 실제시료를 측정하기전에 각 성분의 표준시료를 사용하여 FIA의 구조적 인자(주입 양, 반응코일 길이 그리고 흐름속도)를 결정하였다. Nitrite는 Griess reaction에 의해 sulfanilamide와 반응 후 N-(1-naphthylenediamine dihydrochloride)과 결합하여 azo 색소를 형성시킨 후 540 nm에서 측정하였고, nitrate는 hydrazine을 사용하여 nitride로 환원시킨 후 측정하였다. Ammonia는 Nessler법을 사용하여 440 nm에서 측정하였다. 최적 조건에서 $N(NO_2^-),\;N(NO_3^-)와\;N(NH_4^+)$의 검출한계(S/N=3)는 0.1 ㎍/ML, 0.4 ㎍/mL 그리고 0.3 ㎍/ML이었다. 실제시료를 비색법, ion chromatography 및 FIA로 측정하여 비교한 결과 상호 일치성이 80~125%로 나타내어 만족스러웠다. 시료의 주입횟수는 30회/시간 이상으로 조절할 수 있었다.

• 한국농공학회:학술대회논문집
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• 한국농공학회 2001년도 학술발표회 발표논문집
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• pp.421-425
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• 2001

Among the many parameters describing water quality, total nitrogen content(TN) is regarded as important one in relation to water quality management of the waterbodies for its role in eutrophication process. This study evaluated for accuracy, convenience and promptness of nitrogen analysis methods : (1)UV spectrophotometric method, (2)summation method, (3)cadmium reduction method. And, the detection limit of each method was calculated using EPA method. The UV spectrophotometric method after oxidation appears to be more convenient and accurate in determination of the TN contents than the summation method and cadmium reduction method. The summation method is necessary to separate determinations of the organic nitrogen, ammonia, nitrite, and nitrate. And, because summation method has many other methods for each contents, it can be detected for wide range of concentration.

• 한국토양비료학회지
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• 제41권4호
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• pp.267-272
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• 2008

현장에서의 토양 측정을 위해서는 전처리 과정이 짧을수록 유리하므로 최대한 처리를 하지 않은 토양 시료에 대해 질산태 질소의 측정과 그에 맞는 정량화 방법을 제안하였다. 건조 토양을 분광분석에 그대로 사용하는 경우 산란, 분산되는 빛의 양이 많고 노이즈도 증가하므로 Diffuse reflectance 모드 (Diffuse reflectance infrared Fourier transform spectroscopy: DRIFTS)로 측정하였다. 토양 자체가 나타내는 분광 피크에 의해 질산염의 피크가 가려지는 간섭효과를 보완하기 위해 DRIFTS 스펙트럼에 1차 도함수를 적용하였으며, $1500-1200cm^{-1}$ 영역에서 질산염에 의한 신호의 향상이 확인되었고, 이를 이용해 다변량 회귀분석 모델 (PLSR)을 적용하여 정량화를 수행하였다. 1차 도함수를 이용한 분석모델에서도 각기 다른 종류의 토양을 적용하였을 때 결과치의 신뢰도가 감소하는 결과가 나타났다. 대표적인 토양으로 사질 (sand), 미사질 (sandy loam), 토탄질 (peat), 점토질 (clay) 토양에 대해 각각의 스펙트럼을 특성화하여 해당되는 정량모델을 적용하였다. 그 결과 다양한 종류의 토양에 대한 정량분석의 신뢰도가 향상되었다 ($R^2$>0.95, RPD>6.0). 스펙트럼의 신호처리와 토양 특성별 정량모델의 적용을 통해 현장 시료에 가까운 상태의 토양 질산염을 보다 빠르고 간단하게 평가할 수 있을 것으로 기대되며, 향후에 보다 다양한 조건의 토양에 대해 분광학적 분석을 수행하여 라이브러리가 구축된다면 이러한 기술의 확대 적용이 가능할 것으로 사료된다.