• Proceedings of the Korea Water Resources Association Conference
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• 2010.05a
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• pp.1681-1685
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• 2010

우리나라 가축분뇨 발생량 중 약 10%만이 정화방류 및 공공처리에 의해 처리되고 있으며 2012년 이후 해양투기가 전면 금지됨에 따라 가축분뇨의 자원화 및 육상처리에 대한 대책이 절실한 실정이다. 이에 최근 이에 대한 대안 중 하나로 산림지 및 조림지역에 축산분뇨 액비를 처리하자는 대안이 대두되고 있다. 가축분뇨로부터 생산된 액비는 화학비료를 대신하여 자연순환농업에 효과적으로 사용될 수 있으며, 가축분뇨를 비료로 재활용할 수 있는 장점이 있는 반면, 시용량이나 시용 시기, 시용대상에 따라 환경, 특히 수질 및 지하수에 미치는 영향이 있을 수 있다. 따라서, 저농도액비 시용이 지하수 수질에 미치는 영향 및 환경영향평가, 영향성분 수지의 균형여부 등에 대한 모니터링과 분석이 필요하다. 따라서 본 연구에서는 백합나무 조림지인 바이오순환림에 저농도액비를 시용하였을 때 지하수에 미치는 영향을 살펴보기 위하여 매주 지하수의 수질 모니터링을 실시하였으며, 이를 수질항목에 대하여 분석한 후 액비시용에 따른 수질변화를 제시하였으며, 지하수 오염여부를 결정하는 대표항목인 질산성질소의 오염원을 판별하기 위하여 질소 동위원소비를 분석하였다. 추후 지속적인 지하수 모니터링을 통하여 다양한 수질항목에 대한 분석이 이루어진다면 바이오순환림을 비롯한 산림지에서의 저농도액비 시용에 따른 수질 영향 평가 및 모형 구축의 기초자료로 활용될 수 있을 것으로 판단된다.

• Korean Journal of Ecology and Environment
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• v.49 no.2
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• pp.80-88
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• 2016

In order to reconstruct a benthic foodweb structure and assess the role of benthic microalgaes as a diet source for benthos, we analyzed the carbon and nitrogen stable isotopes of diverse benthos (bivalves, crustaceans, gastropods and fishes) and potential diets (particulate organic matter, sedimentary organic matter, benthic microalgae, seagrass, and macroalgaes) in the intertidal mudflat surrounding Yeongheung Island. The ${\delta}^{13}C$ values of the diets indicated wide ranges (- 26.5‰ to - 8.4‰) while benthos showed a small range of ${\delta}^{13}C$ values (-12.1‰ to - 17.8‰), although they were in the same range. Except for green algaes among the macroalgaes as well as sedimentary organic matter, ${\delta}^{15}N$ values of the diet candidates ($5.7{\pm}1.0$‰) were lighter in comparison to those of the benthos ($11.8{\pm}1.9$‰). Based on the ${\delta}^{13}C$ and ${\delta}^{15}N$ data, the benthos were classified into 3 groups, indicating a different diet and trophic position. But benthic microalgae is the most important diet source for all three benthos groups based on their stable isotope ratios, suggesting benthic microalgae should be a main diet to the intertidal ecosystem. Hence this study highlights that the biomass of benthic microalgae as biological resource should be evaluated for the management of the intertidal ecosystem of Yeongheung Island.

• Korean Journal of Ecology and Environment
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• v.48 no.3
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• pp.147-152
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• 2015

Nitrogen (N) loading from domestic, agricultural and industrial sources can lead to excessive growth of macrophytes or phytoplankton in aquatic environment. Many studies have used nitrogen stable isotope ratios to identify anthropogenic nitrogen in aquatic systems as a useful method for studying nitrogen cycle. In this study to evaluate the precision and accuracy of Kjeldahl processes, two reference materials (IAEA-NO-3, N-1) were analyzed repeatedly. Measured the ${\delta}^{15}N-NO_3$ and ${\delta}^{15}N-NH_4$ values of IAEA-NO-3 and IAEA-N-1 were $4.7{\pm}0.2$‰ and $0.4{\pm}0.3$‰, respectively, which are within recommended values of analytical uncertainties. Also, we investigated spatial patterns of ${\delta}^{15}N-NO_3$ and ${\delta}^{15}N-NH_4$ in effluent plumes from a waste water treatment plant in Han River, Korea. ${\delta}^{15}N-NO_3$ and ${\delta}^{15}N-NH_4$ values are enriched at downstream areas of water treatment plant suggesting that dissolved nitrogen in effluent plumes should be one of the main N sources in those areas. The current study clarifies the reliability of Kjeldahl analytical method and the usefulness of stable isotopic techniques to trace the contamination source of dissolved nitrogen such as nitrate and ammonia.

• Proceedings of the Korean Society of Soil and Groundwater Environment Conference
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• 2005.04a
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• pp.336-339
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• 2005

포천지역의 포천천과 그 주변의 8개 소유역을 대상으로 2003년 8월부터 2004년 8월까지 하천 8개 지점과 기존 지하수 관정 66개소를 선정하여 수리지구화학 및 환경동위원소 연구를 실시하였다. 복합적인 토지이용과 관련하여 연구지역 수계에서는 오염물질 유입이 광역적으로 인지되었으며, 일부 지역에서는 지하수계로의 오염물질 유입이 강하게 나타나 인근 하천까지 영향을 줌이 확인되었다. 오염기원으로 해석되는 대표적인 무기이온종인 $NO_3,\;Cl,\;SO_4$의 존재비를 이용하여 연구 지역의 지표수와 충적 지하수를 크게 3개 수질 그룹으로 분류하였다. 이들 그룹들은 각각 특징적인 충진 특성과 용존 이온의 분포/거동 양상을 나타내는 것으로 해석된다. 본 논문에서는 세 유형의 지표수/충적 지하수 외에 암반 지하수를 포함하여 연구지역 자연수의 수리지구화학 진화 경로와 오염물질의 유입 및 거동 양상에 대하여 토의한다.

• Proceedings of the Korean Environmental Sciences Society Conference
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• 2001.11a
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• pp.71-73
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• 2001

W3와 W4는 질산성 질소의 농도가 자연 토양의 농도 범위에 있고 질산성 질소의 기여율도 토양이 각각 찔.8과 75%로 질산성 질소에 의한 오염이 없다고 볼 수 있다. Sl의 경우 토지 이용이 주거지와 상류에 밭 경작지가 있어서 생활 하수와 화학비료의 영향을 받고 있음을 알 수 있다. S2와 W6의 경우는 생활 하수와 화학비료의 영향이 48.1%와 48.2%로 거의 유사하게 영향을 주고 있음을 알 수 있다. Wl, W2 그리고 W7은 각각 73.2%, 82.7% 그리고 48.8%의 화학비료의 기여율로 보아 주로 화학비료의 영향을 받고 있다고 사료된다.

• Korean Journal of Ecology and Environment
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• v.52 no.1
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• pp.50-64
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• 2019

Recently, quantitative analyses of food web structure based on carbon and nitrogen stable isotopes are widely applied to environmental assessments as well as ecological researches of various ecosystems, particularly rivers and streams. In the present study, we analyzed carbon and nitrogen stable isotope ratios of POM (both planktonic and attached forms), zooplankton, benthic macroinvertebrates and fish collected from 6 sites located at Nakdong River. Samples were collected from upstream areas of 5 weirs (Sangju, Gangjeong-Goryeong, Dalseong, Hapcheon-Changnyeong, and Changnyeong-Haman Weirs) and one downstream area of Hapcheon-Changnyeong Weir in dry season (June) and after rainy season (September). We suggested ranges of their carbon and nitrogen stable isotope ratios and calculated their trophic levels in the food web to compare their temporal and spatial variations. Trophic levels of organisms were relatively higher in Sangju Weir located at upper part of Nakdong River, and decreased thereafter. However, the trophic levels were recovered at the Changnyeong-Haman Weir, the lowest weir in the river. The trophic level calculated by nitrogen stable isotope ratios showed more reliable ranges when they were calculated based on zooplankton than POM used as baseline. The suggested quantitative ecological information of the majority of biological communities in Nakdong River would be helpful to understand the response of river food web to environmental disturbances and can be applied to various further researches regarding the quantitative approaches for the understanding food web structure and function of river ecosystems as well as restoration.

• Korean Journal of Organic Agriculture
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• v.18 no.2
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• pp.257-269
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• 2010

To investigate the possibility of discrimination between organic and non-organic rice using stable isotope nitrogen of natural abundance, organic rice of 17 samples and non-organic rice of 13 samples grown at adjoining organic rice field were collected in 2008. Rice was grinded into brown rice, milled rice and hull, and samples were analysed for nitrogen and $\delta^{15}N$ at NICEM. Authors also made inquiries about N source for both farmers who conduct organic- and non-organic rice cultivation. In order to know whether the $\delta^{15}N$ can be used in discrimination between organic and non-organic rice, discriminant analysis were made with SPSS and logistic method. 1. Organic farmers used manure, rice bran, used mushroom culture, fermented fertilizer (company products), and oil cake, but non-organic farmers applied compound fertilizer. Rice straws were remained in organic rice field while moved out in non-organic field. 2. There were difference in $\delta^{15}N$ among organic rice and its byproduct(7.760????% in hull, 6.720????% in rice), but significant difference was not found between them. And the trend was same between province. Non-organic rice showed similar results. 3. Significant difference of $\delta^{15}N$ were found between organic rice and non-organic rice (p<0.01) and between hull of organic rice and that of non-organic rice hull (p<0.05). $\delta^{15}N$ seemed to be useful criteria for discrimination of organic and non-organic rice. 4. When applied discrimination analysis of SPSS and logistic, there were significant difference between organic rice, non-organic rice and its byproducts except brown rice and hull in SPSS method. Hull can be used as the most useful component for unknown sample prediction with 83.3% probability.

• Korean Journal of Ichthyology
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• v.32 no.2
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• pp.84-90
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• 2020

We investigated carbon and nitrogen isotope ratios (δ¹³C and δ¹⁵N) of the slipmouth Leiognathus nuchalis to reveal the effects of body size, feeding strategy and spatial distribution on the food resource utilization during the migration in the Seomjin estuary and Gwangyang Bay. The δ¹³C values of L. nuchalis caught in the Seomjin estuary where the salinity is lower than 30 psu were much lower than those in the deep-bay area of Gwangyang Bay. Such a spatial heterogeneity in δ¹³C values of the L. nuchalis clearly indicates active feeding within the estuarine habitat. In contrast, the δ¹⁵N values of L. nuchalis showed a consistency among sites, indicating that this species occupies identical trophic level across the whole area. The slipmouth distributed throughout the bay area, reflecting its euryhaline characteristics. However, the distribution pattern appeared to be separated according to body size into smaller individuals in the low-saline estuary and larger ones in the deep bay. Overall results support the plastic feeding strategy of the slipmouth from zooplanktonic (estuarine habitat) to epibenthic (deep-bay habitat) feeder during the migration between estuarine to deep-bay habitats.

• Economic and Environmental Geology
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• v.42 no.6
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• pp.575-589
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• 2009

Groundwater has been extracted for irrigation in Sacheon-Hadong area, which is close to the South Sea. We analyzed chemical components of groundwater to examine the effects of seawater intrusion and agricultural activities in the study area. Most groundwater samples displayed the Na/Cl concentration ratios similar to that of seawater (0.55) with an increasing tendency of electrical conductivity ($227-7,910\;{\mu}S/cm$) towards the coast. In addition, statistical interpretation of the cumulative frequency curves of Cl and $HCO_3$ showed that 30.1% of the groundwater samples were highly affected by seawater intrusion. Groundwaters in the study area mostly belonged to the Ca-Cl and Na-Cl type, demonstrating that they were highly influenced by seawater intrusion and cation exchange. The result of oxygen-hydrogen isotope analysis demonstrated slightly higher $\delta^{18}O$ ((-8.53)-(-6.13)‰) and ${\delta}D$ ((-58.7)-(-43.7)‰) comparing to mean oxygen-hydrogen isotope ratios in Korea. As a result of nitrogen isotope analysis, the $\delta^{15}N-NO_3$ values ((-0.5)-(19.1)‰) indicate two major sources of nitrate pollution (organic nitrogen in soil and animal and human wastes) and mixed source of the two. However, denitrification may partly contribute as a source of nitrogen. According to factor analysis, four factors were identified among which factor 1 with an eigenvalue of 6.21 reflected the influence of seawater intrusion. Cluster analysis indicated the classification of groundwater into fresh, saline, and mixed ones.

• Magazine of the Korean Society of Agricultural Engineers
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• v.43 no.4
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• pp.120-128
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• 2001

Pollution sources and their environmental contributions were investigated to select the best management practices for the effective control of water quality. The nitrogen isotope mass ratio was determined to estimate the nitrate sources and their contribution. Sampling sites were chosen by calculating effluent loads at each watershed. Two liters each of the surface water samples were collected from four sites at Bokha river and two sites and Gwanri river. They were sequentially prepared through distillation method and analyzed using an isotope ratio mass spectrometer(IsoPrime EA). As revealed by the experimental values obtained the mass ratio values ($\delta$$^{5}$ N) of watersheds with a large amount of nonpoint sources were less than +5 an indication that the samples were influenced by chemical fertilizers. However watersheds with large amount of point sources were influenced not only by chemical fertilizers but also by animal and municipal wastes. The mass ratio values of samples generally decreased during rainy days. But during dry days the mass ratio values well-reflected the nitrate sources and the condition of watersheds. Through this study the nitrogen isotope mass ratio has been found to be useful for estimating nitrate sources and their contribution to the rural watersheds.