• Journal of Soil and Groundwater Environment
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• v.27 no.2
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• pp.87-98
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• 2022

This study aims to prepare a technical protocol for identifying the source of nitrate in water using nitrogen (δ¹⁵N) and oxygen (δ¹⁸O) stable isotope ratios. The technical processes for nitrate sources identification are composed of site investigation, sample collection and analysis, isotope analysis, source identification using isotope characteristics, and source apportionment for multiple potential sources with the Bayesian isotope mixing model. Characteristics of various nitrate potential sources are reviewed, and their typical ranges of δ¹⁵N and δ¹⁸O are comparatively analyzed and summarized. This study also summarizes the current knowledge on the dual-isotope approach and how to correlate the field-relevant information such as land use and hydrochemical data to the nitrate source identification.

• Journal of Korean Society on Water Environment
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• v.36 no.2
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• pp.116-124
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• 2020

This study aims to identify the characteristics of organic matter and pollutant sources using water quality and stable isotope ratios (δ¹⁵N, δ¹³C) of the two inflow tributaries (Gulpo (GP) and Anyang (AY) streams). Water samples were analyzed in June and September 2018, and the results showed that the concentrations of nutrients, such as TN and NO₃-N, were increased at GP4, which is located at the downstream of sewage treatment facilities(STFs). TOC and TN ratios showed a strong positive correlation (R² = 0.77, p<0.01) at all points except for GP4. The results of GP's stable isotope ratio analysis do not appear to be a constant cluster compared to AY because GPs with large amounts of pollutants from the industry (metal processing companies, etc.) have less tributary, shorter waterway and significantly different external sources. This could be attributed to different sources of external inflow despite its smaller number of tributaries and shorter waterways than AY. In the first half of the year, the δ¹⁵5N of GP4 was affected by discharge of STFs, while AY3 seemed to have an influence of tributary than the discharge of STFs. Consequently, using water quality, stable isotope ratio and C/N, the sources of contamination in two streams with different contaminants were identified and origin was estimated.

• Korean Journal of Agricultural and Forest Meteorology
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• v.7 no.1
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• pp.15-27
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• 2005

The water and carbon cycles in terrestrial ecosystems are the essential database for better understanding of the causes and the current processes of climate change and for the prediction of its future change. CarboKorea and HydroKorea are dedicated research efforts to develop technologies to quantitatively interpret and forecast carbon/water cycles in typical landscapes of Korea. For this, stable isotope studies have been launched to genetically partition various components of carbon/water cycles in terrestrial ecosystems. From stable isotope studies, practical deliverables such as evaporation, transpiration and gross primary productivity (GPP) can be provided at scales from tower (footprint) to large watersheds. Such reliable field-based information will form an important database to be used for validation of the results from various eco-hydrological models and satellite image analysis which constitute main components of Carbo/HydroKorea project. Stable isotope studies, together with other relevant researches, will contribute to derive quantitative interpretation of carbon/water cycles in terrestrial ecosystems and support Carbo/HydroKorea to become a leading research infrastructure to answer pending scientific and socio-economic questions in relation to global changes.

• Journal of the korean society of oceanography
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• v.32 no.1
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• pp.28-37
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• 1997

Two marine bivalve shells were collected from the eastern and western coastal regions of Korea, respectively. Stable oxygen and carbon isotope profiles are constructed using the incremental sampling along the axis of maximum growth to provide the continuous ${\delta}^{18}$O and ${\delta}^{13}$C records, which register the physical, biological and chemical properties of seawater where the organisms live. Cycles in the ${\delta}^{18}$O profiles are interpreted as annual along with the identification of annual growth bands; the maximum ${\delta}^{18}$O values correspond with the coldest temperature of seawater whereas the minimum ${\delta}^{18}$O values with the warmest temperature. The primary control on the amplitude of the ${\delta}^{18}$O profiles is seasonal variation of seawater temperature. The offset of the baseline between ${\delta}^{18}$O values of the two specimens is attributed to differences in both temperature and seawater ${\delta}^{18}$O values between two localities. The ${\delta}^{13}$C profiles show the similar seasonality of carbon cycling associated with phytoplankton productivity. The offset in the ${\delta}^{13}$C profiles between two specimens may be, as in the case of oxygen isotope profile, attributed to the different ${\delta}^{13}$C value of the seawater DIC (dissolved inorganic carbon) between the western coast and the eastern coast. Relationships between the shell isotopic composition and the coastal water properties of shell growth are readily interpreted from the ${\delta}^{18}$O-${\delta}^{13}$C pair diagram of the shell isotope data, similar to the use of salinity-${\delta}^{18}$O diagram for identifying water masses. The preliminary stable isotope results of this study suggest that mollusk shell isotope geochemistry may be useful to monitor the properties of water masses in the coastal and inner shelf setting around Korea and improve the interpretation of paleoceanography, provided the fossil mollusks are well preserved.

• Analytical Science and Technology
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• v.32 no.2
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• pp.65-76
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• 2019

Despite the expansion of sewage treatment facilities to reduce pollutants in the tributaries of the Han River, water pollution accidents such as fish deaths continue to frequently occur. The purpose of this study was to identify the pollutant sources using water quality and stable isotope ratio (${\delta}^{15}N$, ${\delta}^{13}C$, ${\delta}^{15}N-NH_4$, ${\delta}^{15}N-NO_3$) analysis results in the three inflow tributaries (Gulpocheon (GP), Anyangcheon (AY) and Sincheon (SC)) of the Han River. Water quality was analyzed in June and October from 2013 to 2017, and the results showed that the concentrations of nutrients, such as T-N, $NO_3-N$, and T-P, were increased at GP4, AY3, SC3, and SC4, which lie downstream of sewage treatment facilities. The results of ${\delta}^{15}N$ for June 2017 indicated that the source of nitrogen was sewage or livestock excreta at GP4 and SC4, and organic fertilizers at AY3 and SC3. ${\delta}^{15}N-NO_3$ results suggested that the source of nitrogen was related to organic sewage, livestock or manure at GP4, AY3 and SC4. Therefore, GP4 and SC4 were more influenced by effluent from sewage treatment facilities than by their tributaries, AY3 and SC3 were considered to be influenced more by their tributary than effluent from sewage treatment facilities. With the results of this study, the source of contamination (sewage treatment facility effluent) of river inflow downstream of Han River could be confirmed using water quality and stable isotope ratio.

• Journal of Soil and Groundwater Environment
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• v.20 no.3
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• pp.34-40
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• 2015

Studies using stable water vapor isotopes have been recently conducted over the past two decades because of difficulties in analysis and sample collection in the past. Stable water vapor isotope data provide information of the moisture transport from ocean to continent, which are also used to validate an isotope enabled general circulation model for paleoclimate reconstructions. The isotopic compositions of groundwater and water vapor also provide a clue to how moisture moves from soil to atmosphere by evapotranspiration. International Atomic Energy Agency designates the stations over the world to observe the water vapor isotopes. To analyze the water vapor isotopes, a cryogenic sampling method has been used over the past two decades. Recently, two types of laser-based spectroscopy have been developed and remotely sensed data from satellites have the global coverage. In this review, measurements of isotopic compositions of water vapor will be introduced and some studies using the water vapor isotopes will also be introduced. Finally, we will suggest the future study in Korea.

• Economic and Environmental Geology
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• v.46 no.6
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• pp.495-508
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• 2013

Recently, stable isotopes (${\delta}^{18}O$ and ${\delta}D$) of water are increasingly analyzed using laser-based technologies. These methods have advantages over Isotope Ratio Mass Spectrometry (IRMS) in that they can be used for in-situ measurements and require much less maintenance and preparation work. Two types of laser-based methods are currently available, which have different analytical principles; OA-ICOS (off-axis integrated cavity output spectroscopy) and WS-CRDS (wavelength-scanned cavity ring-down spectroscopy). In the WS-CRDS instrument, water is vaporized at controlled environment and transferred to an optical cavity by nitrogen carrier gas, and stable isotopic compositions of water vapor are measured using the degree of absorbance of specific wavelengths and the ratios of attenuation time of the laser intensity with the sensitivity of ppb to tens of ppt level. In this study, we introduce the principle of the WS-CRDS technology and the performance results including stability and comparisons with Isotope Ratio Mass Spectrometry (IRMS) and suggest possible applications of various topics in isotope hydrology.

• Economic and Environmental Geology
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• v.29 no.2
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• pp.159-170
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• 1996

The gold-silver deposits of the Nakcheon, Eunchi and Jungbong mine in the northern Taebagsan mining district are composed of fissure fil1ing veins emplaced in Precambrian meta-sediments and Jungbongsan granite. Based on the changes of ore texture and mineralogy, ore mineral chemistry, fluid inclusion and mineralizing condition, a regional zoning is recognized from the Nakcheon to the Eunchi and Jungbong ore deposits, and this trend of zoning is also recognized by stable isotope compositions. Stable isotope compositions show that the source of su1fur and carbon is mainly igneous origin, and the water of ore fluid in the Nakcheon ore deposits is mainly magmatic origin but much of meteoric water is involved in ore fluid of the Eunchi and Jungbong ore deposits. The ore deposits of study area is polymetallic meso to epithermal type genetically related to the acidic igneous pluton. Due to the differntial erosion level and mineralized depth, each ore deposits has a slightly different characteristic of mineralization; The Nakcheon ore deposits belong to meso-epithermal type, but the Eunchi and Jungbong ore deposits belong to epithermal type.

• Journal of Ecology and Environment
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• v.43 no.4
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• pp.461-468
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• 2019

Background: This study aimed to identify NO₃^--N sources using the stable isotope δ¹⁵N in Chydorus sphaericus (OF Müller), to investigate hydrological characteristics and nutrient states in artificial wetlands near the Nakdong River. Chydorus sphaericus is dominant in wetlands where aquatic plants are abundant, occurring in high density, and is sensitive to wetland water pollution, making it suitable for identification of NO₃^--N sources. Results: NO₃^--N sources for each wetland were strongly dependent on hydrological characteristics. Wetlands with sewage or rainfall/groundwater as their main sources had high levels of NO₃^--N, whereas wetlands with surface water as their main input had comparatively lower levels. Since wetlands with sewage and rainfall/groundwater as their main water sources were mostly detention ponds, their inputs from tributaries or the main river stream were limited and nutrients such as NO₃^--N easily become concentrated. Changes in NO₃^--N levels at each wetland were closely associated with δ¹⁵N of C. sphaericus. Interestingly, regression analysis also showed positive correlation between δ¹⁵N of C. sphaericus and NO₃^--N level. Conclusions: We conclude that the nitrate stable isotope (δ¹⁵N) of C. sphaericus can be used to elucidate the hydrological characteristics of riverine wetlands. This information is important for maintenance and conservation of artificial wetlands at the Nakdong River.

• Journal of Korean Society on Water Environment
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• v.35 no.6
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• pp.510-519
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• 2019

The 'Stable Isotope Analysis in R' (SIAR), one of the Bayesian mixing models for stable isotopes, has been proven to be useful for source apportionment of nitrates in rivers. In this study, the contribution ratios of nitrate sources were quantified by using the SIAR based on nitrogen and oxygen stable isotope measurements in the Yeongsan River. From the measurements, it was found that the values of δ¹⁵N-NO₃ and δ¹⁸O-NO₃ ranged from -8.2 ‰ to +13.4 ‰ and from +2.2 ‰ to +9.8 ‰, respectively. We further analyzed the contribution ratios of the five nitrate sources by using the SIAR. From the modeling results, the main nitrate source was found to be soil N (29.3 %), followed by sewage (26.7 %), manure (19.6 %), chemical fertilizer (17.9 %) and precipitation (6.3 %). From the results, it was found that the anthropogenic sources, i.e., sewage, manure and chemical fertilizer contribute 64.2% of the total nitrate inflow from the watershed. Due to the significant correlation of δ¹⁵N-NO₃ and lnNO₃^- in this study, the fractionation factors reflecting the biogeochemical processes of stable isotope ratios could be directly obtained. This may make the contribution ratios obtained in this study more precise. The fractionation factors were identified as +3.64 ± 0.91 ‰ for δ¹⁵N-NO₃ (p<0.01) and -5.67 ± 1.73 ‰ for δ¹⁸O-NO₃(p<0.01), respectively, and were applied in using the SIAR. The study showed that the stable isotope method using the SIAR could be applied to quantitatively calculate the contribution ratios of nitrate sources in the Yeongsan River.