• Journal of Wetlands Research
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• v.13 no.3
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• pp.515-522
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• 2011

This study examined the epiphytes using stable isotopes. Separated epiphytes should represent the water quality. In study areas, where agricultural paddies were prevailing, biomass of epiphytes can increase nitrogen isotopes(${\delta}^{15}N$) and as a result decrease in carbon isotopes(${\delta}^{13}C$). Naerin stream and Inbuk upper areas showed higher nitrogen isotopes(${\delta}^{15}N$) than in Hangye and Buk stream. Also, stable carbon isotopes(${\delta}^{13}C$) in Naerin stream and Inbuk streams tended to increase than in Hangye and Buk stream. This can indicate the epiphytes can be a good indicator for water quality pollution.

• 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.

• Korean Journal of Ecology and Environment
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• v.45 no.2
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• pp.242-251
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• 2012

To investigate foodweb of aquatic ecosystem in the Tamjin River, carbon and nitrogen stable isotopes ratios of aquatic organisms, as well as environmental indicators based on the water, were determined in this study. Various organisms such as fishes (Coreoperca kawamebari, Zacco platypus, Cobitis lutheri, and Pungtungia herzi) and periphyton (epilithon and epiphyte), and particulate- and coarse particulate organic matters (POM and CPOM) were collected in upper (Tamjin River, Yuchi Stream, and Omcheon Stream) and lower (TJ-1~TJ-5) reaches of Jangheung Dam. The nitrate concentration and ${\delta}^{15}N$ signature of POM and organisms (invertebrates and fish) were found to be more enriched toward the downstream section of the river. It was determined that allochthonous matter occurring from a tributary alters the chemical character of water, as well as the isotopic signature of organisms contained therein. Attached algae (ephilithon) were identified as a base component of the benthic foodchain further downstream.

• Korean Journal of Ecology and Environment
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• v.51 no.1
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• pp.96-104
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• 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.

• Korean Journal of Ecology and Environment
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• v.47 no.2
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• pp.127-134
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• 2014

Organic carbon and nitrogen stable isotope ratios of particulate organic matter (POM) were determined at 7 stations (6 stations in Han river and Paldang dam outflow station) from May to October 2013, in order to understand the origin of POM at the Han river. ${\delta}^{13}C$ values of POM in four stations showed significant seasonal changes season, but ${\delta}^{15}N$ values were enriched in around Kyeongan stream (K). POC, PN and Chl-a concentration showed a similar seasonal pattern in Kyeongan stream, with an apparent decrease from July to August. POC and PN concentration has a higher correlation with Chl-a concentration in Kyeongan stream (K). ${\delta}^{13}C$ and ${\delta}^{15}N$ values of POM has a lighter value during lower Chl-a concentration peroid, compared to other seasons. Our results revealed that Kyeongan stream (K) seemed to be influenced by substantial amount of organic manure or fertilizer input in 2013, compared to the previous year (2012). These results suggest that the analysis of stable isotope ratios is a simple but useful tool for the identification of organic matter origin in aquatic environments.

• Korean Journal of Ecology and Environment
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• v.50 no.4
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• pp.452-458
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• 2017

The nitrogen isotope value in both ammonium and nitrate ion were determined at 9 stations during both June and August 2016, in order to understand the origin of DIN at the Han river. ${\delta}^{15}N-NO_3$ and ${\delta}^{15}N-NH_4$ values in 8 stations (CP, SB, MHC, P4, SJ, SBC, P2, SC) were no significant variation. However ${\delta}^{15}N-NO_3$ and ${\delta}^{15}N-NH_4$ values in KK (Kyeongan stream) showed significant different in comparison with 8 stations, with an apparent increase of nitrogen isotope values. These results indicate that antropogenic nitrogen source influence on KK station. Also the ${\delta}^{13}C$ and ${\delta}^{15}N$ isotope ratio of phytoplankton (Diatom and Cyanobacteria) in KK (Kyeongan stream) showed heavier values, compared to other study stations. These results indicate that nitrogen isotope value in phytoplankton effects by different nitrogen source in study sites. These results suggest that the analysis of stable isotope ratios is a simple but useful tool for the identification of dissolved inorganic nitrogen origin in aquatic environments.

• 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.

• 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.

• Journal of Korean Society of Environmental Engineers
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• v.33 no.2
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• pp.132-136
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• 2011

The Temporal variability in the food chain structure of bacteria in the sedimentary organic matter was investigated using stable isotope and fatty acid. Potential organic matter sources (Land plant, Marine POM, benthic microalgae, Riverine POM), sedimentary organic matter and bacteria were sampled in Gamo largoon and Nanakita estuary. The main objective of the present study was to determine food sources of bacteria along with temporal variability. Land plant (${\delta}^{13}C$ = -26.6‰ and ${\delta}^{15}N$ = 3.6‰) and Riverine POM (${\delta}^{13}C$ = -25.5‰ and ${\delta}^{15}N$ = 8.9‰) were isotopically distinct from benthic microalgae (${\delta}^{13}C$ = -16.3‰ and ${\delta}^{15}N$ = 6.2‰) and Marine POM (${\delta}^{13}C$ = -20.3‰ and ${\delta}^{15}N$ = 10.3‰). ${\delta}^{13}C$ values of sedimentary organic matter showed a distinct gradient in the range of -20.7‰ to -191‰. The stable carbon and nitrogen isotope values of bacteria in the study were -20.8‰ to -18.6‰ for ${\delta}^{13}C$ and 6.5‰ to 8.6‰ for ${\delta}^{15}N$. From this results based on stable isotope measurements showed that in the bacteria was found to be dominated by Marine POM and Benthicmicoralge during 0 to 20 day. Whereas, terrestrial plant and riverine POM showed little in fluence to bacteria during the experiment.