Geoje, South Korea
Geoje, South Korea

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Hyun S.,Korea Advanced Institute of Science and Technology | Kim J.-M.,Korean Minjok Leadership Academy | Yim U.H.,Oil and POPs Research Group | Shim W.J.,Oil and POPs Research Group | And 2 more authors.
Journal of Asian Earth Sciences | Year: 2013

Variations in long chain alkenone-based sea surface temperature (SST) from a piston core (M04-PC1A) collected from the Korea Plateau in the East Sea (Sea of Japan) were investigated to understand paleoceanographic variations over the last 300,000years. By combining sedimentological and geochemical proxies (the lithological marker of crudely laminated mud, alkenone SST, foraminiferal oxygen isotope values, and 14C age determination) and by comparison with previous works, we examined paleoceanographic variations back to Marine Isotope Stage (MIS) 8, approximately 300,000years B.P. In particular, analysis of alkenones suggests that SSTs were about 8°C and 11°C lower during MIS 8 and MIS 6 than that in the present-day SST, respectively. Furthermore, SST was estimated to be 5°C lower during the Last Glacial Maximum. These significant SST differences among MIS 8, 6, and 2 may be attributable to not only the formation of distinctive water masses, but also to differential alkenone synthesis under different environmental conditions. These results suggest that SSTs in the East Sea during the last three glacial periods (MIS 8, 6, and 2) were different, but rather were closely linked with regional oceanographic conditions overlapped with sensitive responses to the intensity of the East Asian monsoon. Surface-water freshening was a local paleoceanographic consequence that was imprinted in the core during MIS 2 and MIS 6, and potentially during MIS 4. Furthermore, alkenone-based SST data suggested that surface water circulation and biological productivity were strongly associated with the inflow of the Tsushima Warm Current during interglacial periods. © 2013 Elsevier Ltd.

Seo J.-Y.,Korea Institute of Science and Technology | Kim M.,Oil and Pops Research Group | Lim H.-S.,Mokpo National University | Choi J.-W.,Korea Institute of Science and Technology
Marine Pollution Bulletin | Year: 2014

In order to detect the early impact of the Hebei Spirit oil spill on the shallow subtidal macrozoobenthic communities, macrobenthic fauna were collected seasonally for 3years. The alkylated PAHs concentrations within sediments near Mallipo beach remained as high as 129ngg-1 DW one month after the oil spill, but the concentration decreased below the background level thereafter. The number of species and density decreased in 4months compared to those before the oil spill. An opportunistic polychaete, Prionospio paradisea, occurred as a dominant species at subtidal area near Mallipo beach in 10months after the oil spill. Any mass mortality of amphipods and any clear dominance of opportunistic species were not detected except for the stations near Mallipo and Hagampo beaches. The macrobenthic communities at the shallow subtidal stations seemed to have a relatively stable faunal composition, even not fully recovered, in 3years after the Hebei Spirit oil spill. © 2014 Elsevier Ltd.

Jung J.-H.,Oil and POPs Research Group | Kang H.-J.,Korea University | Kim M.,Oil and POPs Research Group | Yim U.H.,Oil and POPs Research Group | And 3 more authors.
Ocean Science Journal | Year: 2015

The performance of a lab-scale flow-through exposure system designed for the evaluation of ecotoxicity due to oil spills was evaluated. The system simulates a spill event using an oil-coated gravel column through which filtered seawater is passed and flows into an aquarium containing fish embryos of olive flounder (Paralichthys olivaceus) and spotted sea bass (Lateolabrax maculates). The dissolved concentrations of individual polycyclic aromatic hydrocarbons (PAHs) in the column effluent were monitored and compared with theoretical solubilities predicted by Raoult’s law. The effluent concentrations after 24 and 48 h were close to the theoretical predictions for the higher molecular weight PAHs, whereas the measured values for the lower molecular weight PAHs were lower than predicted. The ratios of the concentration of PAHs in flounder embryos to that in seawater were close to the lipid-water partition coefficients for the less hydrophobic PAHs, showing that equilibrium was attained between embryos and water. On the other hand, 48 h were insufficient to attain phase equilibrium for the more hydrophobic PAHs, indicating that the concentration in fish embryos may be lower than expected by equilibrium assumption. The results indicate that the equilibrium approach may be suitable for less hydrophobic PAHs, whereas it might overestimate the effects of more hydrophobic PAHs after oil spills because phase equilibrium in an oil-seawater-biota system is unlikely to be achieved. The ecotoxicological endpoints that were affected within a few days are likely to be influenced mainly by moderately hydrophobic components such as 3-ring PAHs. © 2015, Korea Ocean Research & Development Institute (KORDI) and the Korean Society of Oceanography (KSO) and Springer Science+Business Media Dordrecht.

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