• Title/Summary/Keyword: Tidal sand ridge

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Topographic Placement(Structure) and Macro Benthos Community in Winter for the Shellfish Farm of Namsung-ri, Goheung (고흥 남성리 패류양식장의 지형 구조와 저서생물 현장 조사)

  • Jo, Yeong-Hyun;Kim, Yun;Ryu, Cheong-Ro;Lee, Kyeong-Sig;Lee, In-Tae;Yoon, Han-Sam;Jun, Sue-Kyung
    • Journal of the Korean Society of Marine Environment & Safety
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    • v.16 no.2
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    • pp.175-183
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    • 2010
  • To understand the variation of macro benthos community according to the installation of structure and topographic placement in the shellfish farm on tidal flat, the practical example of the tidal shellfish growing area at Namsung-ri Goheung was observed. The results of the research for the field observation were summarized as follows. (1) The ground gradient of the shellfish farm was very flat below about $1^{\circ}$. The shellfish farm ground took the shape of $\sqcup$ from the shoreline to the place of 150 m seawards, and the shape of $\sqcap$ from there to the low tide line. During ebb tide, the $\sqcup$ shape ground stored the sea water, and the $\sqcap$ shape ground was supposed to act as the effect factor to leak slowly or to prevent the outflow. (2) The oyster shell bag or the type of riprap wall as the boundary in the shellfish farm was classified into five types. The air exposure time and flooding time were 181 and 434 minutes, respectively. (3) In the numerical experiment, the deep-sea water wave coming in the study area had 0.5 m of maximum wave height to show the very stable conditions and the wave direction pattern of S-direction was dominant at Naro great ridge, and SE, SSW and S-direction were distributed strongly around the shellfish farm. (4) By the grain size analysis, the sediment around tidal flat consisted of gravel 0.00~5.81(average 1.70)%, sand 14.15~18.39(average 13.23)%, silt 27.59~47.15(average 30.84)% and clay 35.79~55.73(average 36.19)%, and the sediment type was divided into (g)M(lightly gravelly mud), sM(sandy mud) and gM(gravelly mud) by Folk's diagram. (5) The macro benthos community survey conducted in this site in January, 2010 showed that 1 species of Mollusca, 8 species of Polychaeta and 2 species of Crustacea appeared, and 11 species occupying over 1% of total abundance were dominant.

Distribution of Clay Minerals in Surface Sediments of Kunsan Basin, Yellow Sea and their Transport Pathway (황해 군산분지 표층 퇴적물의 점토광물 함량 분포 및 이동경향 연구)

  • RHO, KYOUNG-CHAN
    • The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
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    • v.20 no.4
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    • pp.169-179
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    • 2015
  • To understand the transport pathways of muddy sediment of the Kunsan basin in Yellow Sea, grain sizes and clay mineral of 32 surface sediments and a sediment core were analyzed. In the study area, illite is predominant (63.4~71.9%), followed by chlorite (15.1~20.2%), kaolinite (10.3~17.2%) and smectite (2~6.9%), According to the spatial distribution of the clay minerals, illite, kaolinite+chlorite and smectite show relatively higher contents in the center of the north, northeast, and the south of the study area, respectively. Considering the spatial distribution of clay mineral contents the sand ridge alignments and tidal current pathways, the smectite particles were probably derived from the south of the study area, but kaolinite and/or chlorite particles were mainly transported from the Korean coastal zone. Meanwhile, down-core variation in the contents of clay minerals of the core revealed a distinct change in fine-grained muddy sediment provenance: muddy sediment input from the Korean coastal areas has increased while the input from China has decreased since the last 5,000 year ago, by showing the amount decrease of smectite and the increase of kaolinite+chlorite at the top layer of the late Holocene muddy sediment unit of the core.