• Article

    A Study on the Effect of the Development of Anaerobic Respiration Processes in the Sediment with the Water-column Stratification and Hypoxia and Its Influence on Methane at Dangdong Bay in Jinhae, Korea

    진해 당동만의 성층과 빈산소에 따른 퇴적물내 혐기층 발달이 메탄 거동에 미치는 영향 연구

    Seoyoung Kim and Soonmo An

    김서영, 안순모

    Hypoxia can affect water-atmosphere methane flux by controlling the production and consumption processes of methane in coastal areas. Seasonal methane concentration and … + READ MORE
    Hypoxia can affect water-atmosphere methane flux by controlling the production and consumption processes of methane in coastal areas. Seasonal methane concentration and fluxes were quantified to evaluate the effects of seasonal hypoxia in Dangdong Bay (Gyeongsangnamdo, Jinhae Bay, South Korea). Sediment- water methane flux increased more than 300 times during hypoxia (normoxia and hypoxia each 6, 1900 µmol m-2 d-1), and water-atmospheric methane flux and bottom methane concentration increased about 2, 10 times (normoxia and hypoxia each 190, 420 µmol m-2 d-1; normoxia and hypoxia each 22, 230 nM). Shoaling of anaerobic decomposition of organic matter in the sediments during the hypoxia (August) was confirmed by the change of the depth at which the maximum hydrogen sulfide concentration was detected. Shoaling shortens the distance between the water column and methanogenesis section to facilitate the inflow of organic matter, which can lead to an increase in methane production. In addition, since the transport distance of the generated methane to the water column is shortened, consumption of methane will be reduced. The combination of increased production and reduced consumption could increase sediment-aqueous methane flux and dissolved methane, which is thought to result in an increase in water-atmospheric methane flux. We could not observe the emission of methane accumulated during the hypoxia due to stratification, so it is possible that the estimated methane flux to the atmosphere was underestimated. In this study, the increase in methane flux in the coastal area due to hypoxia was confirmed, and the necessity of future methane production studies according to oxygen conditions in various coastal areas was demonstratedshown in the future. - COLLAPSE
    30 March 2022
  • Article

    Characteristics of Water Quality and Chlorophyll-a in the Seawater Zone of the Yeongsan River Estuary: Long-term (2009–2018) Data Analysis

    영산강 하구 해수역의 수질 및 식물플랑크톤 생체량(chlorophyll-a) 변동 특성: 장기(2009–2018년) 자료 분석

    Sangjun Park and Yongsik Sin

    박상준, 신용식

    The Yeongsan River estuary was altered by a sea dike built in 1981 and the sluice gates in the dike were extended … + READ MORE
    The Yeongsan River estuary was altered by a sea dike built in 1981 and the sluice gates in the dike were extended recently in 2014. The construction has caused changes in water properties and hydrodynamics and also produced disturbances including hypoxia and algal blooms. We analyzed the water quality and chlorophyll-a data (2009–2018) collected seasonally at 3 stations (Sts. 1–3) along the channel of the estuary by the Marine Environmental Monitoring System. Variations in water quality and chlorophyll-a (an index of phytoplankton biomass) were examined and their stressors were also identified by statistics including correlation and multivariate principal component analyses (PCA). The water quality was mainly affected by freshwater discharge from the dike. Salinity, nutrients and chlorophyll-a were especially affected by the discharge and the effect enhanced during summer and at the upper region near the sea dike decreasing downstream. Three factors were extracted for each station in the PCA accounting for 66.07–72.42% of the variations. The first was an external factor associated with freshwater discharge and the second and third were seasonal or biological factors. The results indicate that the water quality is more affected by short-termed and episodic events such as freshwater discharge than seasonal events and the influence of freshwater discharge on water quality is more extensive than that previously reported. This suggests that the boundary of the estuary should be extended to take into account the findings of this study and a management strategy linked to the freshwater zone is required to manage the integrity and water quality of the Yeongsan River estuary. - COLLAPSE
    30 March 2022
  • Article

    Limonium Tetragonum Enhances Osteoblastogenesiswhile Suppressing the Adipocyte Differentiation
    Jung-Ae Kim, Byul-Nim Ahn, Jung Hwan Oh, Fatih Karadeniz, Jung Im Lee, Youngwan Seo, and Chang-Suk Kong
    Halophytes are plants that live in harsh environments in coastal regions and are known for their diverse chemical compositions. Limonium tetragonum, … + READ MORE
    Halophytes are plants that live in harsh environments in coastal regions and are known for their diverse chemical compositions. Limonium tetragonum, a halophyte endemic to Korean shores, is known for its bioactive compounds and is utilized in folk medicine. In this study L. tetragonum extract (LHE) was used to determine and evaluate its anti-osteoporotic properties. Pre-adipocyte and pre-osteoblasts were induced to differentiate along with LHE treatment, and their differentiation was evaluated using differentiation markers. LHE treatment decreased lipid accumulation in 3T3-L1 preadipocytes during adipogenesis. Results indicated that the LHE treatment also decreased the levels of key adipogenic transcription factors: PPARγ, SREBP1c, and C/EBPα. Enhancing osteoblastogenesis by LHE treatment was confirmed in osteoblastogenesis-induced MC3T3-E1 pre-osteoblasts. Cells treated with LHE resulted in increased calcification and alkaline phosphatase (ALP) activity compared with osteoblasts without LHE treatment. Pro-osteogenic and anti- adipogenic effects were also confirmed in D1 murine mesenchymal stromal cells which are capable of differentiation into both adipocytes and osteoblasts. LHE hindered adipogenesis and enhanced osteoblastogenesis in D1 MSCs in a similar fashion. In conclusion, L. tetragonum is believed to possess the potential to be utilized as a nutraceutical ingredient against osteoporotic conditions. - COLLAPSE
    30 March 2022
  • Article

    Otolith Microstructural Organization in the South Georgia Icefish Pseudochaenichthys georgianus (Channichthyidae) and Cautious Considerations on How Otoliths Can Provide Clues on a Species’ Distribution and Migration in Antarctic Waters
    Ryszard Traczyk and Victor Benno Meyer-Rochow
    How in the Antarctic icefish, generally, and Pseudochaenichthys georgianus, in particular, otoliths increase in size and build new material as the … + READ MORE
    How in the Antarctic icefish, generally, and Pseudochaenichthys georgianus, in particular, otoliths increase in size and build new material as the fish ages and passes through different life phases is largely unexplored. Morphometric details of 3418 otoliths of Ps. georgianus from S. Georgia and 318 from S. Shetland, were processed and proportions of the amounts of collagen and aragonite removed by EDTA were determined for different age groups. Microstructural investigations showed that characteristics of the 3-dimensinal collagen net are the reason for the radial direction and orientation of the aragonite needles of approximately 1.0 µm in length in larval and 2.3 µm in length in adult specimens. Earlier generated increment layers from the primordial centre (PC) in the dorsal direction restrict those of the secondary centre (SC), causing new growth layer accretion in different directions. In the otoliths of larval Ps. georgianus, aragonite layers are 0.89 µm wide while in juveniles and adults they measure 1.45–2.86 µm. Otoliths change from a sphere shape in the larvae to a longish object of irregular outline in the older stages. It is tentaively suggested that the observed otolith shape differences at distinct growth stages are due to physical effects related to swimming speeds at particular water depths and locations. To confirm that otoliths, apart from being useful for age analyses, could also serve to establish correlations between developmental stage and the oceanic environment the fish spend time in, further analyses using additional species and state-of-the-art methods like µCT imaging to evaluate otolith volumes and shapes are required. - COLLAPSE
    30 March 2022
  • Article

    Inhibition of Lipase Activity and Preadipocyte Differentiation in3T3-L1 Cells Treated with Sargassum horneri Extract

    괭생이모자반 추출물의 리파아제 저해 활성 및 3T3-L1 지방전구세포 분화억제 효과

    Ji Woo Hong, Ha Young Park, Jae Hyun Park, So Hee Kim, Han A Kim, and Jin-Woo Kim

    홍지우, 박하영, 박재현, 김소희, 김한아, 김진우

    In this study, in order to evaluate the anti-obesity effect of sargassum horneri extract, the effects of the extract on lipase activity … + READ MORE
    In this study, in order to evaluate the anti-obesity effect of sargassum horneri extract, the effects of the extract on lipase activity and preadipocyte differentiation in 3T3-L1 cells were investigated. S. horneri extract between 0.0 and 1.0 mg/mL showed no cytotoxicity and inhibited lipase activity by 68.1%. When S. horneri extract was utilized at levels of 0.25, 0.5, and 1.0 mg/mL in 3T3-L1 cells, preadipocytes differentiation decreased by 11.4, 19.7, and 25.6%, respectively, showing anti-obesity effects. In addition, after treatment with 1.0 mg/mL S. horneri extract, the mRNA expression levels of sterol regulatory element binding proteins-1c (SREBP-1c), peroxisome proliferator activated receptor-γ (PPAR-γ), CCAAT enhancer binding protein-α (CEBP-α), fatty acid synthase (FAS), and stearoyl-CoA desaturase1 (SCD1) in 3T3-L1 cells were significantly decreased (p < 0.05) by 65.2, 54.9, 50.0, 33.8, and 33.8% respectively. These results showed that S. horneri extract suppresses lipase activity and prophylactic preadipocyte differentiation in 3T3-L1, and thus can be used as an anti-obesity agent in functional foods and medicines. - COLLAPSE
    30 March 2022
  • Review

    Responses of the Ross Sea to the Climate Change: Importance of observations in the Ross Sea, Antarctica

    기후변화에 따른 남극 로스해 반응에 관한 고찰: 남극 로스해 관측의 중요성

    Seung-Tae Yoon

    윤승태

    The Ross Sea, Antarctica plays an important role in the formation of Antarctic Bottom Water (AABW) which is the densest water mass … + READ MORE
    The Ross Sea, Antarctica plays an important role in the formation of Antarctic Bottom Water (AABW) which is the densest water mass in global thermohaline circulation. Of the AABW, 25% is formed in the Ross Sea, and sea ice formation at the polynya (ice-free area) developed in front of ice shelves of the Ross Sea is considered as a pivotal mechanism for AABW production. For this reason, monitoring the Ross Sea variations is very important to understand changes of global thermohaline circulation influenced by climate change. In addition, the Ross Sea is also regarded as a natural laboratory in investigating ice-ocean interactions owing to the development of the polynya. In this article, I introduce characteristics of the Ross Sea described in previous observational studies, and investigate variations that have occurred in the Ross Sea in the past and those taking place in the present. Furthermore, based on these observational results, I outline variations or changes that can be anticipated in the Ross Sea in the future, and make an appeal to researchers regarding the importance and necessity of continuous observations in the Ross Sea. - COLLAPSE
    30 March 2022
  • Review

    Decadal Observation and Studies in the Amundsen Sea, Antarctica: Insights from Radiocarbon Values

    10여년간의 서남극 아문젠해 관측과 연구: 방사성탄소동위원소 값을 중심으로

    Minkyoung Kim

    김민경

    The Amundsen Sea in West Antarctica is one of the most affected regions by climate change, but it is one of the … + READ MORE
    The Amundsen Sea in West Antarctica is one of the most affected regions by climate change, but it is one of the least studied realms due to difficulties in access. Korea Polar Research Institute (KOPRI) launched a research project in the Amundsen Sea in 2010 using the icebreaker research vessel (IBRV) Araon and has been conducting various research initiatives. In this paper, previous researches derived from the Amundsen Sea Embayment by Korean researchers are introduced. Through previous studies, researchers have been able to interpret the environmental and biogeochemical changes according to the inflow Circumpolar Deep Water (CDW) and provide information for climate models. In particular, researches using radiocarbon isotopes (14C) were introduced to understand the physical and biogeochemical mechanisms of the carbon cycle in the Amundsen Sea. Opportunely, with the construction of a second icebreaker research vessel, the direction for systematic and long-term polar data acquisition can be presented. - COLLAPSE
    30 March 2022
  • Review

    Current Status and Prospects Regarding Radiocarbon Studies in the East Sea

    동해 방사성탄소동위원소 연구 현황과 전망

    Minkyoung Kim

    김민경

    Together with the development of measurement techniques, radiocarbon (14C) has been increasingly used as a key tool to investigate carbon … + READ MORE
    Together with the development of measurement techniques, radiocarbon (14C) has been increasingly used as a key tool to investigate carbon cycling and associated biogeochemistry in the ocean. In this paper, the current status of radiocarbon studies in the East Sea (Japan Sea) is reviewed. Previously, spatiotemporal distribution and change of the water masses in the East Sea from 1979 to 1999 were investigated by using the 14C in the dissolved inorganic carbon (DIC). Researches on sinking particulate organic carbon (POC) revealed that POC in the deep ocean has more complex and heterogeneous origins than we expected. In particular, since 2011, Korean researchers have been collecting sinking particle samples for more than 10 years, so it is expected that 14C of POC will provide important information to understand carbon cycling in relation to climate change. Although the quantity of 14C data published in the East Sea is still limited, the importance and the future direction of using 14C to understand the biogeochemical mechanisms of carbon cycling and its role as a carbon reservoir in the East Sea are detailed herein. - COLLAPSE
    30 March 2022