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Sedimentation in the lake catchments in South Korea
Orkhonselenge, A.,matsuoka, T.,Tanaka, Y.,Kashiwaya, K.,Kim, S. Korea Association For Quaternary Research 2005 제사기학회지 Vol.19 No.1
This study discusses the soil erosion on hillslopes and sediment deposition in lakes within catchments in South Korea. In order to determine seasonal variations of sedimentation in Yeongcheon and Seondong lakes, the sediment traps were set in the deep part of both lakes and lake sediments have been sampledmonthly from July 2004 to August 2005. Some properties such as highmineral content, fine particle size and high particle density in the Yeongcheon Lake indicate intensive soil erosion, sediment transportation and deposition throughout the catchment for a long time. The high sediment yield in the Seondong Lake is related with higher weathering intensity and extreme soil erosion by running water due to higher seasonal rainfall amount. Rates of erosion and sedimentation in the Seondong Lake are estimated to be higher than those of the Yeongcheon Lake, suggesting that the Seondong Lake is associated with higher precipitation, smaller catchment area, and extreme soil vulnerability to ephemeral erosion by overland flow during the heavy rainfall event. Consequently, both catchments are characterized by different erosion and sedimentation processes, as well as different geomorphic factors (bedrock, soil structure, rainfall intensity and catchment area).
Significance of biogenic silica on paleoenvironmental studies in South Korea
Orkhonselenge, A.,Yang, D.Y.,Nahm, W.H. Korea Association For Quaternary Research 2008 제사기학회지 Vol.22 No.1
Paleoenvironmental evolution in South Korea is investigated on the basis of fluctuations in biogenic silica content in sediments from Cheollipo coast on western shore. The biogenic silica measurement was done by alkaline extraction technique. The concentration of the biogenic silica in the Cheollipo coastal sediments is generally low, with an average of 1.2 %. The proxy of biogenic silica records in Cheollipo sediments implies the significant difference of bio-productivity on Korean Peninsula in comparison with those in lacustrine sediments in interior terrestrial continent of the Eurasia.
어르헌셀렌게,카시와야,오치아이,크리워너거브,나카무라,Orkhonselenge, A.,Kashiwaya, K.,Ochiai, S.,Krivonogov, S.K.,Nakamura, T. 한국제4기학회 2008 제사기학회지 Vol.22 No.1
The present study has focused on the environmental changes and evidences for sedimentation in the Lake Khuvsgul catchment during the Holocene period, inferred from short core sediment (BO03) from the eastern shore of Borsog Bay, which were analyzed in order to review records of the Holocene climatic evolution and Holocene history in Northern Mongolia. For the purpose of reconstruction of natural phenomenon that occurred in the lake catchment system during the Holocene, physical and chemical properties including HCl-soluble material, biogenic silica, organic matter and grain size distribution of minerals in the core sediments have been analyzed in this study. The vertical variations in composition for these properties show distinctly that five lines of paleoenvironmental evidence occurred in the lake catchment during the Holocene. A modified age model resulting from AMS carbon dating for the BO03 core sediment shows timings of these environmental events at 9.5 Kyr BP, 8.0 Kyr BP, 5.6 Kyr BP and 3.2 Kyr BP, respectively. Paleoenvironmental changes in the Lake Khuvsgul catchment system during the Holocene highlight distinctive features of the hydrological regime and geomorphologic evolution in the lake catchment due to regional landscape and global climatic changes corresponding with the Holocene optimum and thermal optimum. In particular, the change of hydrologic regime based on the sedimentological evidence has been caused by not only overland flow due to melting water, but also base flow due to thick permafrost around Khuvsgul region.