https://repository.kopri.re.kr/handle/201206/5341 Thu, 23 Apr 2026 11:52:47 GMT 2026-04-23T11:52:47Z https://repository.kopri.re.kr/handle/201206/9465 Title: Activation of Periodate by Freezing for the Degradation of Aqueous Organic Pollutants Authors: Yoon, Ho Il; Kim, Jungwon; Kim, Kitae; Dominik Heger; Lubica Vetrakova; Lee, Changha; Choi, Yejin Abstract: A new strategy (i.e., freezing) for the activation of IO4？ for the degradation of aqueous organic pollutants was developed and investigated. Although the degradation of furfuryl alcohol (FFA) by IO4？ was negligible in water at 25 °C, it proceeded rapidly during freezing at ？20 °C. The rapid degradation of FFA during freezing should be ascribed to the freeze concentration effect that provides a favorable site (i.e., liquid brine) for the proton-coupled degradation process by concentrating IO4？, FFA, and protons. The maximum absorption wavelength of cresol red (CR) was changed from 434 nm (monoprotonated CR) to 518 nm (diprotonated CR) after freezing, which confirms that the pH of the aqueous IO4？ solution decreases by freezing. The degradation experiments with varying experimental parameters demonstrate that the degradation rate increases with increasing IO4？ concentration and decreasing pH and freezing temperature. The application of the IO4？/freezing system is not restricted to FFA. The degradation of four other organic pollutants (i.e., tryptophan, phenol, 4-chlorophenol, and bisphenol A) by IO4？, which was negligible in water, proceeded during freezing. In addition, freezing significantly enhanced the IO4？-mediated degradation of cimetidine. The outdoor experiments performed on a cold winter night show that the IO4？/freezing system for water treatment can be operated without external electrical energy. Thu, 12 Apr 2018 00:00:00 GMT https://repository.kopri.re.kr/handle/201206/9465 2018-04-12T00:00:00Z https://repository.kopri.re.kr/handle/201206/5863 Title: Distribution of pelagic phytoplankton-derived lipid biomarkers along a transect from the East Sea to the Bering Sea : insights into their suitability as open-water indicators Authors: Gal, Jong-Ku; Shin, Kyung-Hoon; Nam, Seung-il; Simon T. Belt; Ha, Sun-Yong; Lukas Smik; Kim, Junghyun Abstract: In this study we collected suspended particulate matter (SPM) along a transect from the East Sea to the Bering Sea from 18 to 28 July in 2015. We then analyzed the samples for the Arctic sea ice proxy IP25 together with various phytoplankton-derived lipids including a tri-unsaturated highly branched isoprenoid (HBI triene) and two sterols (brassicasterol and dinosterol) to assess the suitability of these compounds for the so-called PIP25 index in the western Arctic region as a proxy for sea ice change in the past. The distributions of some other commonly reported sterols (cholesterol and 24-methylene cholesterol) were also investigated. IP25 could not be detected in any of the samples analyzed, consistent with the nature of the sampling location and season, while the HBI triene was only detected at five sampling sites in the Northwest Pacific and the Bering Sea. In contrast, each of the sterols were detected at each sampling site. Interestingly, brassicasterol concentration showed a strong, positive relationship with cholesterol concentration, but no relationship with chlorophyll a, suggesting that the former might have been associated with not only marine phytoplankton but other sources in the study area, such as zooplankton. Sun, 01 Jan 2017 00:00:00 GMT https://repository.kopri.re.kr/handle/201206/5863 2017-01-01T00:00:00Z https://repository.kopri.re.kr/handle/201206/8298 Title: Trend in sea-ice extent in the Chukchi Sea over the last 140 years Authors: Kim, Junghyun; Nam, Seung-il; Shin, Kyung-Hoon; Kim, D.; Simon T. Belt; Lukas Smik; Gal, Jong-Ku Abstract: 본 연구에서는 척치해에서 획득한 멀티코어(ARA1B-3MUC)의 퇴적물 시료를 사용하여 북극 해빙 프록시 IP25 및 식물플랑크톤 기원의 유기분자생체지표인 삼중-불포화 highly branched isoprenoid(HBI triene)와 두 개의 sterol (brassicasterol 및 dinosterol)을 분석하였다. 본 연구를 통해 IP25보다 좀 더 정량적인 과거 해빙 변화 복원을 위해 제시된 PIP25 지표(index)에 이들이 어느 정도 식물플랑크톤 기원의 유기분자생체지표로서 적합한지 평가하고자 하였다. IP25는 모든 구간의 퇴적층 시료에서 검출되었으며, 이는 지난 140년간 본 연구 해역에서 해빙분포 변화에 대한 중요한 증거를 제공한다. 특히 본 연구를 통해 IP25와 함께 Brassicasterol를 척치해에서 해빙분포 변화를 평가하는 연구에 적용할 수 있지만, 해당 PBIP25를 정량적인 과거 해빙분포 변화를 복원하기 위한 방법으로 사용하는데 주의가 필요하다. Sun, 01 Jan 2017 00:00:00 GMT https://repository.kopri.re.kr/handle/201206/8298 2017-01-01T00:00:00Z https://repository.kopri.re.kr/handle/201206/5604 Title: Holocene variability in sea ice cover, primary production, and Pacific-Water inflow and climate change in the Chukchi and East Siberian Seas (Arctic Ocean) Authors: R. Stein; Nam, Seung-il; F. Niessen; S. Wassmuth; A. Manerung; I. Schade; K. Fahl Abstract: In this study, we present new detailed biomarker-based sea ice records from two sediment cores recovered in the Chukchi Sea and the East Siberian Sea. These new biomarker data may provide new insights on processes controlling recent and past sea ice changes. The biomarker proxy records show (i) minimum sea ice extent during the Early Holocene, (ii) a prominent Mid-Holocene short-term high-amplitude variability in sea ice, primary production and Pacific-Water inflow, and (iii) significantly increased sea ice extent during the last ca. 4.5k cal a BP. This Late Holocene trend in sea ice change in the Chukchi and East Siberian Seas seems to be contemporaneous with similar changes in sea ice extent recorded from other Arctic marginal seas. The main factors controlling the millennial variability in sea ice (and surface-water productivity) are probably changes in surface water and heat flow from the Pacific into the Arctic Ocean as well as the long-term decrease in summer insolation. The short-term centennial variability observed in the high-resolution Middle Holocene record is probably related to solar forcing. Our new data on Holocene sea ice variability may contribute to synoptic reconstructions of regional to global Holocene climate change based on terrestrial and marine archives. Sun, 01 Jan 2017 00:00:00 GMT https://repository.kopri.re.kr/handle/201206/5604 2017-01-01T00:00:00Z