• Title/Summary/Keyword: 섬

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Seismic Structures of the Continental Margin around Smith Island, antarctic Peninsula (남극반도 스미스섬 부근 대륙주변부의 탄성파 구조)

  • Jin, Yong-Keun;Nam, Sang-Heon;Lee, Joo-Han;Hong, Jong-Kuk;Lee, Duk-Kee;Lee, Jong-Ik
    • Journal of the Korean Geophysical Society
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    • v.9 no.4
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    • pp.443-453
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    • 2006
  • Using seismic profiles obtained in the Antarctic Peninsula continental margin around Smith Island located at the southwestern end of the South Shetland Islands, we investigated sediments distribution, sedimentation, continental shelf formation, and tectonic evolution history. The study area is a very unique area that has two tectonic provinces with a tectonic boundary near Smith Island just the landward projection of the Hero Fracture Zone (HFZ). To the southwest of the Island, the margin became inactive margin after the collision of the ridge crest of the Antarctic-Phoenix ridge and trench, whereas to the northeast the margin is still apparently active margin with the spreading center and trench morphology in the sea. Generally the northeastern margin has the shelf sedimentary basins wth thick sedimentary layers, well-developed forearc basin, broad continental slope and distinct trench morphology, and the southwestern margin is characterized by steep and narrow continental slope and localized shelf basins. the mid-shelf basement high structures are distinct in the southwestern margin, which are thought to be formed by thermal effect caused by the subducted spreading centers. The high is observed in the area just northeast of the Island, implying that the tectonic boundary along the landward projection of the HFZ is not sharply defined.

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A Preliminary Study on the Potential Source of Cadmium in the Boseong-Jangheung Mine District (전남 보성-장흥 광화대의 잠정적 카드뮴원에 대한 예비연구)

  • Heo, Chul-Ho;So, Chil-Sup;Yun, Seong-Taek;Shim, Sang-Kyun
    • Economic and Environmental Geology
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    • v.30 no.1
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    • pp.61-65
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    • 1997
  • Cadmium occurs as a minor element in sphalerite ((Zn, Fe)S) from the Boseong-Jangheung gold-silver mine district. We analyzed the abundance of cadmium in sphalerite using an electron probe micro analyzer (EPMA) and discussed the natural sources of cadmium in terms of bedrock geochemistry, in order to preliminarily reconnoiter the potential cadmium contamination in mine districts. Cadmium contents of sphalerites from the Au-Ag mines (Bodeok, Mundeok, Jeonbo, Boknae, Keumsan) in the Boseong-Jangheung district are considerably high, compared with cadmium contents of sphalerites (average = 0.5 wt.% Cd, maximum = 4.4 wt.% Cd) in the world. Sphalerites from the Keumsan mine (average = 9.49 wt.% Cd, maximum=11.22 wt. Cd) are highly enriched in cadmium. Our data suggest that the Boseong-Jangheung area is an important potential site of cadmium contamination in Korea. Based on bedrock geochemistry, natural causes of cadmium enrichment in sphalerite from the mine district are thought to be the mixing of cadmium leached from organic-rich, metasedimentary rocks (including coal) and/or black shales. From this study, we propose that the pinpointing of potential sites of pollution by toxic heavy metals can be done effectively through detailed reconnaisance study on mineralogical compositions of ore minerals such as sphalerite from the mine area.

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Occurence of Zn-Pb Deposits in Danjang-Myeon, Milyang Area (밀양 단장면 일대에 발달하는 아연-연 광화대의 산출특성)

  • Kwak, Ji Young;Kang, Chang Won;Joo, Soo Young;Jeong, Jae Han;Choi, Jin Beom
    • Journal of the Mineralogical Society of Korea
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    • v.28 no.3
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    • pp.279-292
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    • 2015
  • New occurrences of large-scaled Zn-Pb deposits are recently found in the Danjang-myeon, Milyang. They are skarn-type deposits which replaced the intercalated limestone beds in the Jeonggaksan Formation. This study aims at characterizing occurrences, mineralogy, and chemistry of Zn-Pb ores and skarn minerals. Skarn orebodies are mainly found in 3 areas, named Gukjeon-ri, Gorye-ri, and Gucheon-ri orebodies, where sphalerite found as main ore mineral in 200-300 m in height and amount of galena increases as altitude does. Ores are dark grey to dark green in color and closely related with clinopyroxene zone. They occur with hedenbergite, grossular, actinolite, epidote, and small amounts of axinite, calcite, and quartz. Main ore mineral is sphalerite which includes tiny spotted grains of galena and chalcopyrite and becomes rich in grade in association with clinopyroxene and epidote. FeS contents in sphalerite show relatively wide range between 1.53 and 23.07 mole%, whose contents intend to increase towards biotite granite known as ore-related igneous rocks. CdS contents are in the range of 0.22-0.93 mole%, showing decrease tendency from southwest (Gukjeon-ri) to northeast (Gucheon-ri). Zn-Pb deposits developed in Danjang-myeon reveal decrease in temperature with increase of altitude, leading to gradual changes in compositions of ore and skarn minerals.

Rate of Shoreline Changes for Barrier Islands in Nakdong Estuary (낙동강 하구역 울타리 섬의 해안선 변화율)

  • Kim, Baeck-Oon;Khim, Boo-Keun;Lee, Sang-Ryong
    • Journal of Korean Society of Coastal and Ocean Engineers
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    • v.19 no.4
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    • pp.361-374
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    • 2007
  • This study presents long-term shoreline changes of barrier islands in Nakdong Estuary using aerial photographs. Digital photogrammetry is used for constructing mosaic aerial photographs, which yield six sets of shoreline data ranging from 1975 to 2001. Three kinds of rate of shoreline changes such as EPR (End Point Rate), JKR(Jackknife Rate) and LRR (Linear Regression Rate) are computed by a GIS-based Digital Shoreline Analysis Systems. There have been remarkable changes both in Sinja Island and Doyodeung. Western part of Sinja Island advanced seaward, whereas eastern part retreated landward, giving appearance that the island rotated counterclockwise. Rate of shoreline changes at both ends reach 20 m/yr. Doyodeung occurred newly in front of Baekhapdeung in 1993, resulting in shoreline advance in a rate of 40 m/yr. Rate of shoreline changes differ both within and between barrier islands and have a tendency to increase eastward. To understand this spatial variability of rate of shoreline changes, it is suggested to make a detailed investigation into the impact of coastal development on hydrodynamic and sedimentary processes.

Influences of Coastal Upwelling and Time Lag on Primary Production in Offshore Waters of Ulleungdo-Dokdo during Spring 2016 (2016년 춘계 울릉도-독도주변해역에서 동해 연안 용승과 시간차에 의한 일차생산력 영향)

  • Baek, Seung Ho;Kim, Yun-Bae
    • Korean Journal of Environmental Biology
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    • v.36 no.2
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    • pp.156-164
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    • 2018
  • In order to investigate the upwelling and island effects following the wind storm events in the East Sea (i.e., Uljin-Ulleungdo-Dokdo line) during spring, we assessed the vertical and horizontal profiles of abiotic and biotic factors, including phytoplankton communities. The assessment was based on the Geostationary Ocean Color Imager (GOCI) and field survey data. A strong south wind occurred on May 3, when the lowest sea level pressure (987.3 hPa) in 2016 was observed. Interestingly, after this event, huge blooms of phytoplankton were observed on May 12 along the East Korean Warm Current (EKWC), including the in the offshore waters of Ulleungdo and Dokdo. Although the diatoms dominated the EKWC area between the Uljin coastal waters and Ulleungdo, the population density of raphidophytes Heterosigma akashiwo was high in the offshore waters of Ulleungdo-Dokdo. Based on the vertical profiles of Chlorophyll-a (Chl. a), the sub-surface Chl. a maximum appeared at 20 m depths between Uljin and Ulluengdo, whereas relatively high Chl. a was distributed equally across the entire water column around the waters of Ulleungdo and Dokdo islands. This implies that the water mixing (i.e., upwelling) at the two islands, that occurred after the strong wind event, may have brought the rapid proliferation of autotrophic algae, with nutrient input, to the euphotic layer. Therefore, we have demonstrated that a strong south wind caused the upwelling event around the south-eastern Korean peninsula, which is one of the most important role in occurring the spring phytoplankton blooms along the EKWC. In addition, the phytoplankton blooms may have potentially influenced the oligotrophic waters with discrete time lags in the vicinity of Ulleungdo and Dokdo. This indicates that the phytoplankton community structure in the offshore waters of Ulleungdo-Dokdo is dependent upon the complicated water masses moving related to meandering of the EKWC.

Occurrence of the Pb-Zn Skarn Deposits in Gukjeon Mine, Korea (국전 Pb-Zn 스카른 광상의 산출상태)

  • Yang, Chang-Moon;Choi, Jin-Beom
    • Journal of the Mineralogical Society of Korea
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    • v.23 no.4
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    • pp.413-428
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    • 2010
  • The Gukjeon Pb-Zn mine was recognized as skarn deposits which replaced the limestone layer of the Jeongkansan Formation by intrusion of biotite granite in late Cretaceous. The Jeongkansan Formation is mainly composed of tuffaceous shale, and interlayers of sandstone, andesitic tuff, limestone, and conglomerate. The limestone layer is located in the lower part of the Jeongkansan Formation with 6~8 m in thickness and about 500 m in length. The Gukjeon deposits are divided into the Jukgang ore bodies once mined underground and the eastern ore bodies. Main ores are sphalerite and galena, in association with small amounts of chalcopyrite, arsenopyrite, pyrite, and pyrrhotite, etc. Skarns mainly consist of clinopyroxenes and Ca-garnets, associated with actinolite, chlorite, axinite, and calcite, etc. The Jukgang ore bodies show symmetrical distribution of zoning outward, representing clinopyroxene (hedenbergite) zone, clinopyroxene-garnet (grossular) zone, garnet (andradite) zone, and alteration zone of hornfels. $Fe^{2+}$ contents in clinopyroxenes increase with decreasing sphalerite grade. Sphalerite ores are found in all zones and $Fe^{2+}$ contents in sphalerite increase in the same way as those in clinopyroxenes, implying that clinopyroxene and sphalerite are closely related each other. It is concluded that the Gukjeon ores occurred in the ore rich zone of high grade sphalerite with less pyrite in assoication with clinopyroxene.

A Comparative Study on The Improvement of Logistics Support in Island Area using Unmanned Vehicles (무인 이동체를 활용한 도서 지역의 군수지원 향상 비교 연구)

  • Lee, Hak-Jae;Shin, Sang-Hee;Hwang, Seong-Guk;Kim, Moo-Young;Kwon, Ki-Sang
    • Journal of the Korea Academia-Industrial cooperation Society
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    • v.20 no.9
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    • pp.315-322
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    • 2019
  • Recently, the Marine Corps of South Korea started to introduce and possess its own weapon systems. On the other hand, the level of maintenance is lower than that of other military forces, and depending on the other military forces, maintenance occurs intermittently when transporting weapons systems. In this case, unmanned vehicles can be used to reduce the cost, manpower, time, and risk of carrying weapons systems. In addition, the transport of weapon systems between islands or between an island and inland of the Marine Corps using unmanned vehicles is easier in terms of the maintenance level and surrounding environment than other military forces. This paper compares the improvement of operational availability and cost of spare parts in terms of logistics support when using unmanned vehicles in the West Sea area, and quantitatively show the efficiency and usability of the weapon system. To compare operational availability and costs for spare parts, a simulation was performed based on the OO weapons system between islands or between an island and inland, and the results were compared and analyzed.

Evaluation of Particulate Matter's Traits and Reduction Effects in Urban Forest, Seoul (서울 청량리 교통섬과 홍릉숲의 미세먼지 특성과 저감효과 평가)

  • Kim, Pyung-Rae;Park, Chan-Ryul
    • Korean Journal of Environment and Ecology
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    • v.35 no.5
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    • pp.569-575
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    • 2021
  • This study analyzed the effect of forests on reducing particulate matter by investigating the particulate matter concentration and influencing factors between urban forest and traffic forest. The concentrations of particulate matter in Hongreung Experimental Forest (urban forest) and a forest (traffic forest) formed at the intersection of Cheongryangri Station in Dongdaemun-gu, Seoul were measured with the light scattering method instrument from January to November 2018. During the study period, the average PM10 concentrations in the urban forest and the traffic forest were 12.5㎍/m3 and 15.7 ㎍/m3, respectively, and the average PM2.5 concentrations were 16.6㎍/m3and 6.9 ㎍/m3, respectively. Comparing the concentration by the urban atmospheric measurement network of the Ministry of Environment and the concentration in urban forests showed that the reduction rate of PM10 was 66.9±28.6% in urbanforest and 58.6±44.1% in traffic forest and that of PM2.5 was 71.3±23.0% and 64.9±31.3%. The difference in the reduction rate of particulate matter is likely related to the size and structure of the urban forest, and the wind velocity is considered the reduction factor.

Effects of Heavy Metal Concentrations on Seed Germination and Rhizome Development of Campanula takesimana Nakai (중금속 농도가 섬초롱꽃 종자 발아 및 유근 발달에 미치는 영향)

  • Kim, Tae Hyun;Kim, Do Hyun;Im, Hyeon Jeong;Choi, Kyu Seung;Kim, Sang Geun;Song, Chi Hyeon;Oh, Beom Seok;Kim, Yang Su;Song, Ki Seon;Won, Chang O
    • Proceedings of the Plant Resources Society of Korea Conference
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    • 2019.10a
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    • pp.39-39
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    • 2019
  • 섬초롱꽃은 울릉군에 한정적으로 분포하는 여러해살이풀이다. 산림청에서는 약관심종(LC) 등급의 희귀식물이자 특산식물로 분류하고 있으며, 꽃의 관상가치가 특히 높아 화단용 소재, 절화용, 화분재배 등으로 흔히 이용되고 있다. 따라서 본 연구는 섬초롱꽃의 대량증식 시, 중금속이 미칠 수 있는 영향에 대해 파악하고자 수행하였다. 실험에 사용한 중금속은 카드뮴(Cd), 철(Fe) 두 종류이며, 두 종류 모두 1% 한천(agar)배지에 10, 25, 50, 100, 200 mg/L 농도로 녹여 사용하였다. 발아율 및 유근 생장을 위해 종자 및 유묘를 치상 후, $25^{\circ}C$ 항온 생장상에서 발아율 및 유근 발달을 관찰하였다. 발아율 측정결과, 아무처리도하지 않은 1% 한천(agar) 배지에서 $62.7{\pm}7.4%$로 가장 높았고 중금속 농도가 높아질수록 감소하였다. 카드뮴(Cd) 처리구에서는 10, 25, 50, 100, 200 mg/L 농도에서 각각 $17.3{\pm}1.3$, $2.7{\pm}1.3$, $1.3{\pm}1.3$, 0, 0%로 나타났다. 한편, 철(Fe) 처리구에서는 10, 25, 50, 100, 200 mg/L 농도에서 각각 $46.7{\pm}4.8$, $24.0{\pm}2.3$, $36.0{\pm}6.9$, $20.0{\pm}2.3$, 0%로 나타났다. 유근의 평균 생장 길이(mm)는 아무처리도 하지 않은 1% 한천(agar) 배지에서 19.6 mm로 가장 높았고, 중금속 농도가 높아질수록 낮게 나타났다. 카드뮴(Cd) 처리구에서는 10, 25, 50, 100, 200 mg/L 농도에서 각각 4.6 mm, 1.9 mm, 0.7 mm, 0.9 mm, 0 mm 생장한 것으로 나타났다. 한편, 철(Fe) 처리구에서는 10, 25, 50, 100, 200 mg/L 농도에서 각각 15.9 mm, 8.6 mm, 8.1 mm, 0.9 mm, 0 mm 생장한 것으로 나타났다. 실험결과를 종합해 볼 때, 섬초롱꽃 종자 발아 및 유근 생장의 억제는 카드뮴(Cd) 처리구에서 높게 나타났고, 철(Fe) 처리구에서는 비교적 영향을 덜 미치는 것으로 나타났다. 특히 카드뮴은 10 mg/L 농도만 처리하더라도 약 3.6~4.2배의 발아율 생장율 감소가 나타나, 섬초롱꽃 대량증식 시, 치명적일 것으로 판단된다. 본 실험의 결과는 섬초롱꽃 종자를 이용한 대량증식 및 유묘재배에 있어, 토양을 선택하는데 중요한 기초자료로서 활용될 것으로 기대된다.

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Time-series Analysis of Baramarae Beach in Anmyeondo Using Aerial Photographs and Field Measurement Data (항공사진과 기준목 측정자료를 이용한 안면도 바람아래 해빈의 시계열 변화 분석)

  • KIM, Jang-soo;JANG, Dong-Ho
    • Journal of The Geomorphological Association of Korea
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    • v.18 no.2
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    • pp.39-51
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    • 2011
  • In this study, the shape of the Baramarae beach, Anmyeondo Area in West Coast of Korea and the changes in the sedimentation and erosion environment were analyzed in time series. As a result of the time series analysis of the shape of the Baramarae beach using aerial photographs from 1967 to 2009, the sand spit that developed in the southern part of Halmi Island was found to have had an EEN direction, but it was changed to a NNS direction, as reflected in the 2009 aerial photographs, as it gradually shifted to the west. In the onsite measurement, the H-3, H-4, H-5, and H-6 spots showed a superior sedimentation environment and the H-7, H-8, and H-9 spots showed a superior erosion environment. It was thus found that sedimentation is superior in the southwest beach and that erosion is superior in the northeast beach. The results in the spots between H-3 and H-6 indicate that the sand in the beach could not move to the northeast beach of Halmi Island due to the bank that had been established in the southwest beach of the island. On the other hand, it seems that superior erosion takes place in spots H-7 to H-9 in the northeast beach, where sand is not provided from the southwest beach of Halmi Island. It was found from the seasonal analysis that the season when superior sedimentation takes place in all the spots is autumn, and that the season when superior erosion takes place is summer. Superior sedimentation takes place in winter and spring in the southeast side and in summer in the northwest side.