https://repository.kopri.re.kr/handle/201206/9839 2026-04-21T10:18:48Z https://repository.kopri.re.kr/handle/201206/12098 Title: Molecular Distributions and Compound-Specific Stable Carbon Isotopic Compositions of Plant Waxn-Alkanes in Marine Aerosols along a North-South Transect in the Arctic-Northwest Pacific Region Authors: Kim, Jung-Hyun; Park, Jiyeon; Kim, Sol-Bin; Shin, Kyung-Hoon; Kim, Sookwan; Gim, Yeontae Abstract: A geographical source ofn-alkanes in marine aerosols was assessed along a North-South transect in the Arctic-Northwest Pacific region. Marine aerosol samples were collected during the ARA08 cruise with the R/V Araon between 28 August and 28 September 2017. We investigated molecular distributions ofn-alkanes (homologous series of C(16)to C-34) and compound-specific stable carbon isotopes (delta C-13) ofn-C-27,n-C-29, andn-C-31. Unresolved complex mixtures (UCM) showed a latitudinal trend from the Arctic Ocean to the northwest Pacific Ocean, highlighting an increasing influence of the plume of polluted air exported from East Asian countries. The anthropogenic input was further evidenced by high U/R ratios (>5) and low CPI17-23(0.6-1.4). The occurrence of high molecular weight (HMW)n-alkanes with high CPI27-31(>3) indicated the biogenic input of terrestrial higher plant leaf waxes in all studied samples. The delta C-13 of HMWn-alkanes was influenced by both the relative contributions from the C-3/C(4)plant sources and from fossil fuel combustions. The back-trajectory analyses provided evidence that changes in molecular distributions and delta C-13 ofn-alkanes were due to the long-range atmospheric transport of anthropogenic and biogenic organic materials from North American and East Asian countries to the Arctic Ocean and the remote northwest Pacific Ocean, respectively. 2020-05-01T00:00:00Z https://repository.kopri.re.kr/handle/201206/10979 Title: Reconstructing spring sea ice concentration in the Chukchi Sea over recent centuries: insights into the application of the PIP25 index Authors: Kim, Junghyun; Gal, Jong-Ku; Jun, Sang-Yoon; Smik, Lukas; Kim, Dahae; Belt, Simon T.; Park, Kwangkyu; Shin, Kyung-Hoon; Nam, Seung-il Abstract: In this study, we aimed to reconstruct spring (April？June)sea ice changes in the western Arctic Ocean over recent centuries(ca. the last 250 years) by measuring biomarker distributions in a multicore (ARA01B-03MUC)retrieved from the Chukchi Shelf region and to evaluate outcomes against known or modelled estimates of sea ice conditions. Specifically, we analyzed for the Arctic sea ice proxy IP25 and assessed the suitability of a further highly branched isoprenoid (HBI) lipid (HBI III), epibrassicasterol, and dinosterol as complementary biomarkers for use with the so-called phytoplankton marker-IP25 index (PIP25; PIIIIP25, PBIP25, and PDIP25, respectively). The presence of IP25 throughout core ARA01B-03MUC confirms the occurrence of seasonal sea ice at the study site over recent centuries. From a semi-quantitative perspective, all three PIP25 indices gave different trends, with some dependence on the balance factorc, a term used in the calculation of the PIP25 index. PIIIIP25-derived spring sea ice concentration (SpSIC) estimates using a c value of 0.63, determined previously from analysis of Barents Sea surface sediments, were likely most reliable, since SpSIC values were high throughout the record (SpSIC > 78%), consistent with the modern context for the Chukchi Sea and the mean SpSIC record of the 41 CMIP5 climate models over recent centuries. PBIP25-based SpSIC estimates were also high (SpSIC 108%？127%), albeit somewhat over-estimated, when using a c value of 0.023 obtained from a pan-Arctic distribution of surface sediments. In contrast, PDIP25 values using a pan-Arctic c value of 0.11, and PIP25 data based on the mean biomarker concentrations from ARA01B-03MUC, largely underestimated sea ice conditions(SpSIC as low as 13%), and exhibited poor agreement with instrumental records or model outputs. On the other hand, PBIP25 values using a cfactor based on mean IP25 and epi-brassicasterol concentrations exhibited a decline towards the core top, which resembled recent decreasing changes in summer sea ice conditions for the Chukchi Sea; however, further work is needed to test the broader spatial generality of this observation. 2019-12-01T00:00:00Z https://repository.kopri.re.kr/handle/201206/10508 Title: Trace element systematics in cold seep carbonates and associated lipid compounds Authors: Wang, Xudong; Bayon, Germain; Kim, Junghyun; Lee, Dong-Hun; Kim, Dahae; Gueguen, Bleuenn; Rouget, Marie-Laure; Barrat, Jean-Alix; Toffin, Laurent; Feng, Dong Abstract: Seeping of methane-rich fluids at submarine cold seeps drives intense microbial activity and precipitation of authigenic carbonates. Some trace elements play an important role in the biogeochemical processes operating at cold seeps, especially as specific enzymatic co-factors related to methanogenesis and the anaerobic oxidation of methane (AOM). However, it is unclear whether microbial trace metal utilization can be traced by the geochemical composition of seep carbonates. In this study, we analyzed a series of authigenic carbonate samples recovered from various seep settings worldwide and report for the first time trace element concentrations for total lipid fractions, combined with biomarker analyses and determination of elemental abundances in associated inorganic mineral phases (carbonate phases, sulfides, organic compounds and detrital fractions). Our results indicate marked enrichments of Co, Ni, Cu, Mo and W in the archaeal and bacterial lipids associated with authigenic carbonates, which can all be ascribed to previously identified enzymatic pathways. In addition to the microbial communities involved in AOM, which most likely control specific lipid-bound enrichments of Co, Ni, Mo and W in seep carbonates, Cu was found to display higher concentrations in the lipid fractions extracted from a few authigenic carbonate samples formed closer to the sediment-water interface, hence possibly related to the presence of aerobic methane-oxidizing bacterial assemblages in the near seafloor environment. While the above mentioned trace metals are relatively enriched in all studied inorganic and organic fractions, the very low W concentrations measured in carbonate phases, combined with their pronounced enrichment in associated lipid fractions and inferred microbial requirement, suggest that tungsten depletion in pore waters could possibly act as a limiting factor on AOM at cold seeps. Finally, two other trace elements (Li and Ti) also displayed particular enrichments in studied lipid fractions, which, despite no reported evidence, could possibly indicate that they are also involved as metalloenzymes in microbial methane oxidation processes at cold seeps. 2019-12-01T00:00:00Z https://repository.kopri.re.kr/handle/201206/10944 Title: Holocene environmental changes in Dicksonfjorden, west Spitsbergen, Svalbard Authors: Joo, Young Ji; Forwick, Matthias; Park, Kwangkyu; Joe, Young Jin; Son, Yeong-Ju; Nam, Seung-il Abstract: Multi-proxy analyses of two sediment cores from Dicksonfjorden were performed to reconstruct Holocene environmental conditions in this northern tributary of Isfjorden, the largest fjord system on Svalbard. Factors affecting the depositional processes include shifts in sources of inorganic and organic sediments, ice rafting, and regional glacio-isostatic rebound. Sediments were derived from Palaeozoic siliciclastic and carbonate bedrocks occurring at the fjord head and sides, respectively. Their relative contributions were controlled by falling relative sea-level and the resulting progradation of the major stream and delta systems closer to the core sites. Deposition of clasts from sea ice rafting persisted throughout the most of the Holocene. Following a period of low, but continuous, clast fluxes (~ c. 11 ？ 7 ka), ice rafting was most intensive between c. 7 and 3 ka. It can be related to extensive seasonal sea ice formation caused by regional climate cooling. The prograding deltas also provided coarse sediments. Reduced ice rafting from c. 3 ka suggests enhanced formation of more shorefast and/or permanent sea ice, suppressing sea ice rafting in the fjord, in response to the cool climate and reduced heat flux from Atlantic Water. Episodic inflow of Atlantic Water, however, as well as low turbidity of surface water, can account for a higher amount of marine organic matter produced in the outer fjord. The sedimentary record in Dicksonfjorden, where tidewater glaciers are absent, reflects similar regional climate and oceanographic variations as reconstructed in fjords on western Spitsbergen that are influenced by tidewater glaciers. 2019-09-01T00:00:00Z