https://repository.kopri.re.kr/handle/201206/9756 2026-04-21T14:14:25Z 2026-04-21T14:14:25Z Gal, Jong-Ku Kim, Junghyun Kim, Solbin Lee, Sang Han Yoo, Kyu-Cheul Shin, Kyung-Hoon https://repository.kopri.re.kr/handle/201206/10888 2022-03-24T07:14:37Z 2019-02-01T00:00:00Z

Title: Application of the newly developed nutrient diol index (NDI) as a sea surface nutrient proxy in the East Sea for the last 240 years Authors: Gal, Jong-Ku; Kim, Junghyun; Kim, Solbin; Lee, Sang Han; Yoo, Kyu-Cheul; Shin, Kyung-Hoon Abstract: We assessed the applicability of the nutrient diol index (NDI) as a proxy for sea surface nutrients by analyzing sediments from a box core (ES14-BC03) collected in the southwestern continental slope of the East Sea, or the Japan Sea (hereafter the East Sea). The estimated sedimentation rate based on the Pb-210 chronology was 0.15 cm yr(-1) over the last 240 yrs. The NDI-derived phosphate (0.69 mu mol L-1) and nitrate (8.63 mu mol L-1) concentrations for the core-top sediment were within the average phosphate (0.26 +/- 0.08 mu mol L-1) and nitrate (3.38 +/- 2.32 mu mol L-1) concentration ranges for the last similar to 20 years, accounting for both estimation error and variation in observational data. The distributions of the NDI-diols varied slightly through time, grouping into two distinct clusters (Cluster 1 and Cluster 2) in both principle component analysis (PCA) and hierarchical clustering of principal components (HCPC). Cluster 2 represented a time period with higher relative abundances of the C-28 and C-30 1,14-diols, resulting in higher NDI-derived nutrient concentrations than those of other periods. Interestingly, during this period, the U-37(K')-derived sea surface temperatures (SSTs) also decreased. These results indicate that higher surface nutrient conditions and colder SSTs occurred between 1884 CE and 1911 CE, which might be associated with stronger upwelling intensity at the study site. This study is the first application of the NDI to a down-core, demonstrating that the NDI can be a useful proxy that provides helpful information about past sea surface nutrient conditions.

2019-02-01T00:00:00Z Kim, Dahae Kim, Jung-Hyun Kang, Sujin Park, Kwangkyu Lee, Dong-Hun Jin, Young Keun Nam, Seung-il Shin, Kyung-Hoon https://repository.kopri.re.kr/handle/201206/12280 2022-03-24T07:15:23Z 2019-01-01T00:00:00Z

Title: Tracing terrestrial organic matter in two contrasting Arctic systems: A case study in the Mackenzie Trough in the Canadian Beaufort Sea and in Wijdefjorden in the Svalbard Archipelago Authors: Kim, Dahae; Kim, Jung-Hyun; Kang, Sujin; Park, Kwangkyu; Lee, Dong-Hun; Jin, Young Keun; Nam, Seung-il; Shin, Kyung-Hoon Abstract: The Arctic is warming twice as fast as other parts of the Earth by thawing permafrost and thus mobilizing the organic carbon (OC) stored in permafrost. With ongoing climate changes, inputs of terrestrial OC into the Arctic Ocean have been expected to increase through several pathways including river discharges, coastal erosions, and glacial discharges. In order to understand the Arctic carbon cycle, knowledge of OC dynamics with various regional characteristics is essential. The Mackenzie River, which flows into the Beaufort Sea, is the fourth-largest Arctic river in terms of freshwater discharge, but the first in terms of sediment discharge. Wijdefjorden is the longest fjord in Svalbard archipelago, located in the northern portion of the island of Spitsbergen, which supplies glacigenic terrestrial material through glacial discharges. In this study, two contrasting Arctic environments were investigated using surface sediments collected along Mackenzie Trough and Wijdefjorden during the expeditions of the R/V ARAON (ARA04C, ARA05C, and ARA08C in 2013, 2014, and 2017) and R/V Helmer Hanssen (HH17 in 2017), respectively. We analyzed the samples for bulk (e.g. Corg/Norg ratio, δ13Corg, and δ15Norg) and molecular (concentrations and δ13C of n-alkanes) parameters to assess sources of organic matter. In addition, we analyzed the radiocarbon content (Δ14C) to evaluate the contribution of fossil and non-fossil to the overall OC pool of OC. Our results will provide information on the contribution of organic carbon to the thawing of terrestrial permafrost in the two contrasting Arctic environmental systems.

2019-01-01T00:00:00Z Kim, Junghyun Kang, Sujin Bong, Yeon-Sik Park, Kwangkyu Kang, Tae-Woo Park, Yong-Se Kim, Dahae Choi, Seunghyun Joo, Young Ji Choi, Bohyung Nam, Seung-il Lee, Sang-Mo Shin, Kyung-Hoon https://repository.kopri.re.kr/handle/201206/10863 2022-03-24T07:14:31Z 2018-12-01T00:00:00Z

Title: Inter-laboratory comparison of stable carbon and nitrogen isotopic composition data using elemental analyzer-isotope ratio mass spectrometers Authors: Kim, Junghyun; Kang, Sujin; Bong, Yeon-Sik; Park, Kwangkyu; Kang, Tae-Woo; Park, Yong-Se; Kim, Dahae; Choi, Seunghyun; Joo, Young Ji; Choi, Bohyung; Nam, Seung-il; Lee, Sang-Mo; Shin, Kyung-Hoon Abstract: In this study, inter-laboratory comparison was done using elemental analyzer-isotope ratio mass spectrometers (EA-IRMSs) to determine carbon and nitrogen contents as well as stable carbon and nitrogen isotopic compositions (δ13C and δ15N) of five environmental samples containing lake and marine sediments, higher plant leaves, and fish muscle, and one organic analytical standard (Protein (Casein) Standard OAS). Five national laboratories participated in this comparison study, and each laboratory analyzed all five samples and the analytical standard. Results showed that variations in total organic carbon (TOC) and total nitrogen (TN) contents as well as δ13CTOC and δ15NTN values among the laboratories were large compared to the analytical uncertainties. The results highlighted the inhomogeneity of the test samples and thus, the need to select suitable standard reference materials for future inter-laboratory studies. Further inter-laboratory comparison exercises could promote good measurement practices in the acquisition of stable carbon and nitrogen isotopic composition data.

2018-12-01T00:00:00Z Lee, Dong-Hun Kim, Junghyun Lee, Yung Mi Stadnitskaia, Alina Jin, Young Keun Niemann, Helge Kim, Young-Gyun Shin, Kyung-Hoon https://repository.kopri.re.kr/handle/201206/10865 2022-03-24T07:14:17Z 2018-12-01T00:00:00Z

Title: Biogeochemical evidence of anaerobic methane oxidation on active submarine mud volcanoes on the continental slope of the Canadian Beaufort Sea Authors: Lee, Dong-Hun; Kim, Junghyun; Lee, Yung Mi; Stadnitskaia, Alina; Jin, Young Keun; Niemann, Helge; Kim, Young-Gyun; Shin, Kyung-Hoon Abstract: TS2In this study, we report lipid biomarker patterns and phylogenetic identities of key microbial communities mediating anaerobic oxidation of methane (AOM)in active mud volcanoes (MVs) on the continental slope of the Canadian Beaufort Sea. The carbon isotopic compositions (d13C) of sn-2- and sn-3-hydroxyarchaeol showed the highly 13C-depleted values (-114‰ to -82 ‰) associated with a steep depletion in sulfate concentrations within 0.7m of sediment depths. This suggested the presence of methan otrophic archaea involved in sulfate-dependent AOM, albeit in a small amount. The ratio of sn-2-hydroxyarchaeol to archaeol (> 1) and operational taxonomic units (OTUs) indicated that archaea of the anaerobic methanotrophic archaea (ANME) CE2 clades ANME-2c and ANME-3 were 15 involved in AOM. Higher d13C values of archaeol and biphytanes (BPs; -55.2+/-10.0‰ and -39.3+/-13.0 ‰, respectively) suggested that archaeal communities were also assimilating AOM-derived inorganic carbon. Furthermore, the distinct distribution patterns of methanotrophs in the three MVs appears to be associated with varying intensities of ascending gas fluids. Consequently, our results suggest that the niche diversification of active mud volcanoes has shaped distinct archaeal communities that play important roles in AOM in the Beaufort Sea.

2018-12-01T00:00:00Z