• Ocean Science Journal
• /
• v.42 no.4
• /
• pp.223-230
• /
• 2007

To understand the origin and biogeochemistry of the organic matter in surface sediments of Lake Shihwa and Lake Hwaong, organic nitrogen, inorganic nitrogen, labile organic carbon, and residual organic carbon contents as well as stable isotope ratios for carbon and nitrogen were determined by KOBr-KOH treatment. Ratios of organic carbon to organic nitrogen $(C_{org}/N_{org})$ (mean = 24) were much higher than ratios of organic carbon to total nitrogen $(C_{org}/N_{tot})$ (mean= 12), indicating the presence of significant amounts of inorganic nitrogen in the surface sediments of both lakes. Stable isotope ratios for organic nitrogen were, on average, $5.2\%_{\circ}$ heavier than ratios of inorganic nitrogen in Lake Shihwa, but those same ratios were comparable in Lake Hwaong. This might be due to differences in the origin or the degree of degradation of sedimentary organic matter between the two lakes. In addition, stable isotope ratios for labile organic carbon were, on average, $1.4\%_{\circ}$ heavier than those for residual organic carbon, reflecting the preferential oxidation of $^{13}C$-enriched organic matter. The present study demonstrates that KOBr-KOH treatment of sedimentary organic matter can provide valuable information for understanding the origin and degradation state of organic matter in marine and brackish sediments. This also suggests that the ratio of $(C_{org}/N_{org})$ and stable isotope ratios for organic nitrogen can be used as indexes of the degree of degradation of organic matter.

• Korean Journal of Ecology and Environment
• /
• v.38 no.spc
• /
• pp.8-11
• /
• 2005

Carbon stable isotope ratios of producers varied in lake ecosystems. In tile present study, we tried to estimate the seasonal variations of carbon isotope ratios of phytoplankton and benthic diatoms in a strongly acidic lake ecosystem. Lake Katanuma is a volcanic, strongly acidic lake (average pH of 2.2), located in Miyagi, Japan. Only two algal species dominate in Lake Katanuma; Pinnularia acidojaponica as a benthic diatom, and Chlamydomonas acidophila as a green alga. Carbon isotope values of P. acidojaponica varied seasonally, while those of particulate organic matter, which were mainly composed of C. acidophila remained fairly stable. The differences suggested that $CO_2$ gas was more frequently limited for P. acidojaponica than C. acidophila, since high density patches of benthic diatoms were sometimes observed on the lake sediment. Generally, carbon concentration mechanisms (CCMs)of microalgae can fix bicarbonate in lakes, and affect the carbon isotope values of microalgae. While, in Lake Katanuma, CCMs of the microalgae may scarcely function because of high $CO_2$ gas concentration and low pH. This is the reason for low seasonal amplitude of carbon isotope values of phytoplankton relative to those in other lakes.

• Journal of Marine Life Science
• /
• v.7 no.2
• /
• pp.61-73
• /
• 2022

Stable isotope analysis (SIA) is being used in various research fields including environmental science, ecology, biogeochemistry, forensics, and archeology. In this paper, for the purpose of enhancing applications and utilizations stable isotope analysis techniques to aquaculture research, we would like to introduce the background knowledge necessary to utilize stable isotope analysis techniques. In particular, with a focus on the approach using natural abundance, the principle of fractionation (change in isotope ratio) that occurs in the process of the integration of elements into biological tissues and how stable isotope ratios are determined by fractionation. This paper is intended to suggest whether SIA is used as a valuable tool in the fields of ecology and environmental science. With the understanding of the field of stable isotopes through this paper, various applications of stable isotope ratios are expected in fisheries science and aquaculture research in the future.

• Korean Journal of Ecology and Environment
• /
• v.46 no.2
• /
• pp.175-184
• /
• 2013

Organic carbon and total nitrogen stable isotope ratios of suspended materials were determined at 3 stations (from Mongtan Bridge to Youngsan river estuary barrage) (n=6, each) from November 2008 to August 2009, in order to understand the origin of particulate organic matter at the Estuary of Youngsan River. Allochthonous organic matter, ammonia-N and silicate were increased after heavy rain (in August). Carbon isotope ratios were significantly different between stations in November and August, and it was possible to determine the origin of organic matter. The heavier nitrogen isotope ratios, as well as higher phosphate concentrations, were found in November than other sampling times. Livestock wastewater and farmland input was likely the main causes of these high values. In addition, YS3 station, the nearest site to estuary barrage, appears to be affected by a substantial amount of livestock wastewater and farmland input, considering that nitrogen isotope ratios were heavier than those at the upper sites. These results suggest that the analysis of stable isotope ratios is a simple but useful tool for the determination of organic matter origin in aquatic environments.

• Journal of Ginseng Research
• /
• v.42 no.4
• /
• pp.485-495
• /
• 2018

Background: The geographical origin of Panax ginseng Meyer, a valuable medicinal plant, is important to both ginseng producers and consumers in the context of economic profit and human health benefits. We, therefore, aimed to discriminate between the cultivation regions of ginseng using the stable isotope ratios of C, N, O, and S, which are abundant bioelements in living organisms. Methods: Six Korean ginseng cultivars (3-yr-old roots) were collected from five different regions in Korea. The C, N, O, and S stable isotope ratios in ginseng roots were measured by isotope ratio mass spectrometry, and then these isotope ratio profiles were statistically analyzed using chemometrics. Results: The various isotope ratios found in P. ginseng roots were significantly influenced by region, cultivar, and the interactions between these two factors ($p{\leq}0.001$). The variation in ${\delta}^{15}N$ and ${\delta}^{13}C$ in ginseng roots was significant for discriminating between different ginseng cultivation regions, and ${\delta}^{18}O$ and ${\delta}^{34}S$ were also affected by both altitude and proximity to coastal areas. Chemometric model results tested in this study provided discrimination between the majority of different cultivation regions. Based on the external validation, this chemometric model also showed good model performance ($R^2=0.853$ and $Q^2=0.738$). Conclusion: Our case study elucidates the variation of C, N, O, and S stable isotope ratios in ginseng root depending on cultivation region. Hence, the analysis of stable isotope ratios is a suitable tool for discrimination between the regional origins of ginseng samples from Korea, with potential application to other countries.

• Journal of Soil and Groundwater Environment
• /
• v.27 no.2
• /
• pp.87-98
• /
• 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
• /
• v.35 no.6
• /
• pp.510-519
• /
• 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.

• Journal of Ginseng Research
• /
• v.41 no.2
• /
• pp.195-200
• /
• 2017

Background: The natural ratios of carbon (C), nitrogen (N), and sulfur (S) stable isotopes can be varied in some specific living organisms owing to various isotopic fractionation processes in nature. Therefore, the analysis of C, N, and S stable isotope ratios in ginseng can provide a feasible method for determining ginseng authenticity depending on the cultivation land and type of fertilizer. Methods: C, N, and S stable isotope composition in 6-yr-old ginseng roots (Jagyeongjong variety) was measured by isotope ratio mass spectrometry. Results: The type of cultivation land and organic fertilizers affected the C, N, and S stable isotope ratio in ginseng (p < 0.05). The ${\delta}^{15}N_{AIR}$ and ${\delta}^{34}S_{VCDT}$ values in ginseng roots more significantly discriminated the cultivation land and type of organic fertilizers in ginseng cultivation than the ${\delta}^{13}C_{VPDB}$ value. The combination of ${\delta}^{13}C_{VPDB}$, ${\delta}^{15}N_{AIR}$, or ${\delta}^{34}S_{VCDT}$ in ginseng, except the combination ${\delta}^{13}C_{VPDB}-^{34}S_{VCDT}$, showed a better discrimination depending on soil type or fertilizer type. Conclusion: This case study provides preliminary results about the variation of C, N, and S isotope composition in ginseng according to the cultivation soil type and organic fertilizer type. Hence, our findings are potentially applicable to evaluate ginseng authenticity depending on cultivation conditions.

• Journal of Korean Society on Water Environment
• /
• v.36 no.2
• /
• pp.116-124
• /
• 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 Ecology and Environment
• /
• v.51 no.1
• /
• pp.96-104
• /
• 2018

Stable isotope approach for aquatic ecology and environmental sciences has been introduced as very useful technique since 1980s and also has been applied to investigate various issues in aquatic ecology and environmental study last 10 years in Korea. Especially carbon and nitrogen isotope ratios have been mainly used to understand food web energy flow and ecosystem structure. In addition, nitrogen isotope ratio has been applied for nitrogen cycle and source identification as well as biomagnification studies. However, large temporal or spatial variations of nitrogen isotope ratio of primary producer have been found in many aquatic environments, and it is regarded as the critical problems to determine trophic level of aquatic animals. Recently, the compound specific isotope analysis of nitrogen within individual amino acids has been developed as an alternative method for trophic ecology. This article introduces the progress history of stable isotope application in aquatic ecology and environmental sciences, and also suggests new direction based on future prospects in stable isotope ecology and environmental study.